Patent Grant
10738799
The present invention relates generally to linear actuator assemblies and actuating methodologies thereof, and more particularly to a linear actuator assembly having a pump assembly and a linear actuator and control methodologies thereof in a fluid pumping system, including providing normal and fail-safe modes of operation.
Linear actuator assemblies are widely used in a variety of applications ranging from small to heavy load applications. The linear actuators, e.g., a hydraulic cylinder, in linear actuator assemblies are used to cause linear movement, typically reciprocating linear movement, in systems such as, e.g., hydraulic systems. Often, one or more linear actuator assemblies are included in the system which can be subject to frequent loads in a harsh working environment, e.g., in the hydraulic systems of industrial machines such as excavators, front-end loaders, and cranes. Thus, it is strongly desirable that these linear actuator assemblies be durable and reliably function even in a harsh working environment.
However, in a conventional machine, the actuators components are provided separately and usually include numerous parts such as a hydraulic cylinder, a hydraulic pump, a motor, a fluid reservoir and appropriate valves that must be connected. The motor drives the hydraulic pump to provide pressurized fluid from the fluid reservoir to the hydraulic cylinder in a predetermined manner, which in turn causes the piston rod of the cylinder to move within the body of the cylinder. When the hydraulic cylinder is retracted, extra fluid is sent back to the fluid reservoir. To control the flow in the hydraulic system, the hydraulic pump can be a variable-displacement hydraulic pump and/or a directional flow control valve (or another type of flow control device) can be included in the system. In these types of systems, the motor that drives the operation of the hydraulic pump is often run at constant speed and the directional flow control valve, for example, can provide the appropriate porting to the hydraulic cylinder to extend or retract the hydraulic cylinder. Typically, the motor and hydraulic pump are run at a high speed, which builds up temperature in the hydraulic fluid. Thus, the reservoir also acts to keep the average fluid temperature down by increasing the fluid volume in the system. However, these hydraulic systems can be relatively large and complex. In addition, the various components are often located spaced apart from one another. To interconnect these parts, various additional components like connecting shafts, hoses, pipes, and/or fittings are used in a complicated manner. Moreover, these components are susceptible to damage or degradation in harsh working environments, thereby causing increased machine downtime and reduced reliability of the machine. In addition, when a hydraulic pump fails because its motor has failed, there may be no safe way to shut down the system or to operate the system until the current operation has completed.
Further limitation and disadvantages of conventional, traditional, and proposed approaches will become apparent to one skilled in the art, through comparison of such approaches with embodiments of the present invention as set forth in the remainder of the present disclosure with reference to the drawings.
Preferred embodiments of linear actuators and actuation methodologies provide for a compact and reliable design of a linear actuator. Exemplary embodiments are directed to a linear hydraulic actuator system and method in an industrial machine that provides for precise control of the hydraulic fluid flow and/or pressure in the system by using a variable-speed and/or a variable-torque pump. Exemplary embodiments are also directed to a linear hydraulic actuator system and method that provides for a normal mode of operation and a fail-safe mode of operation. The linear actuator system and method of control thereof discussed below are particularly advantageous in a closed-loop type system since system and method of control provides for a more compact configuration without increasing the risk of pump cavitation or high fluid temperatures as in conventional systems. In an exemplary embodiment, a hydraulic system includes an integrated linear hydraulic actuator assembly that controls a load. The integrated linear hydraulic actuator assembly includes a hydraulic cylinder and an integrated hydraulic pump assembly having a fluid driver assembly, at least one sensor assembly and two valve assemblies to provide hydraulic fluid to the linear hydraulic actuator to operate the load. The hydraulic system further includes a means for adjusting at least one of a flow and a pressure in the system to an operational set point. In some embodiments, the adjustment means exclusively uses the at least one hydraulic pump to adjust the flow and/or the pressure in the system, i.e., without the aid of another flow control device, to control the flow and/or pressure in the system to the operational set point.
In another exemplary embodiment, a fluid system includes a pump assembly having at least one variable-speed and/or a variable-torque pump, a linear actuator that is operated by the fluid to control a load, and a controller that establishes a speed and/or torque of the pump. As used herein, “fluid” means a liquid or a mixture of liquid and gas containing mostly liquid with respect to volume. The pump provides fluid to the linear actuator, which can be, e.g., a fluid-actuated cylinder that controls a load (e.g., a boom of an excavator or some other equipment or device that can be operated by a linear actuator). Each pump includes a prime mover and a fluid displacement assembly. The fluid displacement assembly can be driven by the prime mover such that fluid is transferred from the inlet port to the outlet port of the pump. In some embodiments, the controller controls a speed and/or a torque of the prime mover so as to exclusively adjust a flow and/or a pressure in the fluid system. “Exclusively adjust” means that the flow and/or the pressure in the system is adjusted by the prime mover (or prime movers depending on the pump configuration and number of pump assemblies) and without the aid of another flow control device, e.g., flow control valves, variable flow piston pumps, and directional flows valves to name just a few. That is, unlike a conventional fluid system, the pump is not run at a constant speed and/or use a separate flow control device (e.g., directional flow control valve) to control the flow and/or pressure in the system. In some embodiments, the hydraulic system includes two fluid drivers and the controller operates the system in a normal mode in which the prime movers of the fluid drivers are independently driven so as to synchronize contact between the respective fluid displacement members. The controller switches to a fail-safe mode of operation upon determination of an abnormal operation of a prime mover such that the pump assembly is operated using only the operative prime mover.
In some embodiments, the preferred linear actuators include a hydraulic cylinder assembly and at least one pump assembly, which form a closed-loop hydraulic system. Each pump assembly can include at least one storage device and at least one hydraulic pump with a corresponding set of valve assemblies. The hydraulic cylinder assembly includes a cylinder housing, a movable piston disposed in an actuator chamber inside the cylinder housing, and a piston rod fixedly attached to the piston. The piston rod is axially movable along with the piston which defines a retraction chamber and an extraction chamber within the actuator chamber. When installed in an industrial machine, the fluid-operated linear actuator or hydraulic cylinder is attached to two structural elements that require relative movement between them. The relative movement can be linear, rotational (when the structural elements are pivotally attached) or a combination of the two.
Exemplary embodiments of the pump in each pump assembly has at least one fluid driver. The fluid driver includes a prime mover and a fluid displacement assembly. The prime mover drives the fluid displacement assembly and the prime mover can be, e.g., an electric motor, a hydraulic motor or other fluid-driven motor, an internal-combustion, gas or other type of engine, or other similar device that can drive a fluid displacement member. In some embodiments, the pump includes at least two fluid drivers and each fluid displacement assembly includes a fluid displacement member. The prime movers independently drive the respective fluid displacement members such that the fluid displacement members transfer fluid (drive-drive configuration). The fluid displacement member can be, e.g., an internal or external gear with gear teeth, a hub (e.g. a disk, cylinder, or other similar component) with projections (e.g. bumps, extensions, bulges, protrusions, other similar structures or combinations thereof), a hub (e.g. a disk, cylinder, or other similar component) with indents (e.g., cavities, depressions, voids or similar structures), a gear body with lobes, or other similar structures that can displace fluid when driven.
In some embodiments, the pump includes one fluid driver and the fluid displacement assembly has at least two fluid displacement members. The prime mover drives a first displacement member, which then drives the other fluid displacement members in the pump (a driver-driven configuration). In both the drive-drive and driver-driven type of configurations, the fluid displacement member can work in combination with a fixed element, e.g., pump wall, crescent, or other similar component, and/or a moving element such as, e.g., another fluid displacement member when transferring the fluid. The configuration of the fluid displacement members in the pump need not be identical. For example, one fluid displacement member can be configured as an external gear-type fluid driver and another fluid driver can be configured as an internal gear-type fluid driver.
In some exemplary embodiments, at least one shaft of a fluid driver, e.g., a shaft of the prime mover and/or a shaft of the fluid displacement member and/or a common shaft of the prime mover/fluid displacement member (depending on the configuration of the pump), is of a flow-through configuration and has a through-passage that allows fluid communication between at least one port of the pump and at least one fluid storage device. In some embodiments, the fluid storage device or fluid storage devices are attached to the pump body such that they form one integrated device and the flow-through shaft(s) can be in direct fluid communication with the fluid reservoir(s) in the storage device(s). One end of the through-passage of the flow-through shaft is configured for fluid communication with either the inlet port or the outlet port of the pump. In some embodiments, the connection from the end of the through-passage to the port of the pump can be through a intervening device or structure. For example, the through-passage of the flow-through shaft can connect to a channel within the pump casing or connect to a hose, pipe or other similar device, which is then connected to a port of the pump. The other end of the through-passage can have a port for fluid communication with a fluid storage device, which can be a pressure vessel, an accumulator, or another device that is fluid communication with the fluid system and can store and release fluid. The configuration of the flow-through shaft and intervening device/structure assembly can also include valves that can be operated based on whether the through-passage function is desired and/or to select a desired pump port and/or a storage device.
The summary of the invention is provided as a general introduction to some embodiments of the invention, and is not intended to be limiting to any particular drive-drive configuration or drive-drive-type system, to any particular through-passage configuration or to any particular parallel or serial flow configuration for the linear actuator assembly. It is to be understood that various features and configurations of features described in the Summary can be combined in any suitable way to form any number of embodiments of the invention. Some additional example embodiments including variations and alternative configurations are provided herein.
The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate exemplary embodiments of the invention, and, together with the general description given above and the detailed description given below, serve to explain the features of the exemplary embodiments of the invention.
Exemplary embodiments of the present invention are directed to a linear actuator system with a linear actuator and at least one integrated pump assembly connected to the linear actuator to provide fluid to operate the linear actuator. The integrated pump assembly includes a pump with at least one fluid driver comprising a prime mover and a fluid displacement assembly to be driven by the prime mover such that fluid is transferred from a first port of the pump to a second port of the pump. The pump assembly also includes two valve assembles to isolate the pump from the system. The linear actuator system also includes a controller that establishes at least one of a speed and a torque of the at least one prime mover to exclusively adjust at least one of a flow and a pressure in the linear actuator system to an operational set point. The linear actuator system can include sensor assemblies to measure system parameters such as pressure, temperature and/or flow. When the linear actuator assembly contains more than one pump assembly, the pump assemblies can be connected in a parallel or serial configuration depending on, e.g., the requirements of the system.
In some embodiments, the pump includes at least one prime mover that is disposed internal to the fluid displacement member. In other exemplary embodiments of the fluid delivery system, at least one prime mover is disposed external to the fluid displacement member but still inside the pump casing, and in still further exemplary embodiments, the at least one prime mover is disposed outside the pump casing. In some exemplary embodiments of the linear actuator system, the pump includes at least two fluid drivers with each fluid driver including a prime mover and a fluid displacement member. In other exemplary embodiments of the linear actuator system, the pump includes one fluid driver with the fluid driver including a prime mover and at least two fluid displacement members. In some exemplary embodiments, at least one shaft of a fluid driver, e.g., a shaft of the prime mover and/or a shaft of the fluid displacement member and/or a common shaft of the prime mover/fluid displacement member (depending on the configuration of the pump), is a flow-through shaft that includes a through-passage configuration which allows fluid communication between at least one port of the pump and at least one fluid storage device.
The exemplary embodiments of the linear actuator system will be described using embodiments in which the pump in the pump assembly is an external gear pump with either one or two fluid drivers, the prime mover is an electric motor, and the fluid displacement member is an external spur gear with gear teeth. However, those skilled in the art will readily recognize that the concepts, functions, and features described below with respect to the electric-motor driven external gear pump can be readily adapted to external gear pumps with other gear configurations (helical gears, herringbone gears, or other gear teeth configurations that can be adapted to drive fluid), internal gear pumps with various gear configurations, to pumps with more than two fluid drivers, to prime movers other than electric motors, e.g., hydraulic motors or other fluid-driven motors, internal-combustion, gas or other type of engines or other similar devices that can drive a fluid displacement member, to pumps with more than two fluid displacement members, and to fluid displacement members other than an external gear with gear teeth, e.g., internal gear with gear teeth, a hub (e.g. a disk, cylinder, or other similar component) with projections (e.g. bumps, extensions, bulges, protrusions, other similar structures, or combinations thereof), a hub (e.g. a disk, cylinder, or other similar component) with indents (e.g., cavities, depressions, voids or similar structures), a gear body with lobes, or other similar structures that can displace fluid when driven.
The hydraulic cylinder assembly 3 includes a cylinder housing 4, a piston 9, and a piston rod 6. A head flange 13 is mounted on end of the cylinder housing 4 and an end flange 14 is mounted on the other end of the cylinder housing 4. The cylinder housing 4 defines an actuator chamber 5 therein, in which the piston 9 and the piston rod 6 are movably disposed. The piston 9 is fixedly attached to the piston rod 6 on one end of the piston rod 6 in the actuator chamber 5. The piston 9 can slide along the interior wall 16 of the cylinder housing 4 in either direction 17. The piston may have one or more bearings 37 on its outer surface. The piston rod 6 can also slide in either direction 17 along with the piston 9. The piston 9 defines two sub-chambers within the actuator chamber 5. As seen in
The pump assembly 2, including valve assemblies 122 and 123, is conjoined with the hydraulic cylinder assembly 3. “Conjoined with” means that the devices are fixedly connected or attached so as to form one integrated unit or module. The pump assembly 2 includes a pump 10 and a storage device 170. In the illustrated embodiment, the pump 10 is an external gear pump. However, as discussed below the present disclosure is not limited to an external gear pump. A port 22 of the pump 10 is in fluid communication with the retraction chamber 7 via valve assembly 122 and a port 24 of the pump 10 is in fluid communication with valve assembly 123 which in turn is in fluid communication with the extraction chamber 8 via a passage defined by pipe 43, flange passage 45, pipe 12, and flange passage 49. The port 24 of the pump 10 is in fluid communication with valve assembly 123 which in turn is in fluid communication with the extraction chamber 8 via a passage defined by pipe 11 and flange passage 47. The fluid passages between hydraulic cylinder 3, pump assembly 2, and valve assemblies 122 and 123 can be either internal or external depending on the configuration of the linear actuator assembly 1.
As seen in
As seen in
As seen in
As discussed above, the gear bodies can include cylindrical openings 51, 71 which receive motors 41, 61. In an exemplary embodiment, the fluid drivers 40, 60 can respectively include outer support members 48, 68 (see
As shown in
In an exemplary embodiment, as shown in
In some embodiments, a second shaft can also include a through-passage that provides fluid communication between a port of the pump and a fluid storage device. For example, as shown in
In the exemplary embodiment shown in
In an exemplary embodiment, the storage device 170 may be pre-charged to a commanded pressure with a gas, e.g., nitrogen or some other suitable gas, in the gas chamber 174 via the charging port 180. For example, the storage device 170 may be pre-charged to at least 75% of the minimum required pressure of the fluid system and, in some embodiments, to at least 85% of the minimum required pressure of the fluid system. However, in other embodiments, the pressure of the storage device 170 can be varied based on operational requirements of the fluid system. The amount of fluid stored in the storage device 170 can vary depending on the requirements of the fluid system in which the pump 10 operates. For example, if the system includes an actuator, such as, e.g., a hydraulic cylinder, the storage vessel 170 can hold an amount of fluid that is needed to fully actuate the actuator plus a minimum required capacity for the storage device 170. The amount of fluid stored can also depend on changes in fluid volume due to changes in temperature of the fluid during operation and due to the environment in which the fluid delivery system will operate.
As the storage device 170 is pressurized, via, e.g., the charging port 180 on the cover 178, the pressure exerted on the separating element 176 compresses any liquid in the fluid chamber 172. As a result, the pressurized fluid is pushed through the through-passages 184 and 194 and then through the channels in the end plate 82 (e.g., channel 192 for through-passage 194—see
As the pressurized fluid flows from the storage device 170 to a port of the pump 10, the fluid exits the tapered portion 204 at point 206 and enters an expansion portion (or throat portion) 208 where the diameter of the through-passage 184, 194 expands from the diameter D2 to a diameter D3, which is larger than D2, as measured to manufacturing tolerances. In the embodiment of
The stabilized flow exits the through passage 184, 194 at end 210. The through-passage 184, 194 at end 210 can be fluidly connected to either the port 22 or port 24 of the pump 10 via, e.g., channels in the end plate 82 (e.g., channel 192 for through-passage 194—see
The cross-sectional shape of the fluid passage is not limiting. For example, a circular-shaped passage, a rectangular-shaped passage, or some other desired shaped passage may be used. Of course, the through-passage in not limited to a configuration having a tapered portion and an expansion portion and other configurations, including through-passages having a uniform cross-sectional area along the length of the through-passage, can be used. Thus, configuration of the through-passage of the flow-through shaft can vary without departing from the scope of the present disclosure.
In the above embodiments, the flow-through shafts 42, 62 penetrate a short distance into the fluid chamber 172. However, in other embodiments, either or both of the flow-through shafts 42, 62 can be disposed such that the ends are flush with a wall of the fluid chamber 172. In some embodiments, the end of the flow-through shaft can terminate at another location such as, e.g., in the end plate 80, and suitable means such, e.g., channels, hoses, or pipes can be used so that the shaft is in fluid communication with the fluid chamber 172. In this case, the flow-through shafts 42, 62 may be disposed completely between the upper and lower plates 80, 82 without penetrating into the fluid chamber 172.
In the above embodiments, the storage device 170 is mounted on the end plate 80 of the casing 20. However, in other embodiments, the storage device 170 can be mounted on the end plate 82 of the casing 20. In still other embodiments, the storage device 170 may be disposed spaced apart from the pump 10. In this case, the storage device 170 may be in fluid communication with the pump 10 via a connecting medium, for example hoses, tubes, pipes, or other similar devices. An exemplary operation of the pump 10 is discussed below.
As seen in
To prevent backflow, i.e., fluid leakage from the outlet side to the inlet side through the contact area 78, contact between a tooth of the first gear 50 and a tooth of the second gear 70 in the contact area 78 provides sealing against the backflow. The contact force is sufficiently large enough to provide substantial sealing but, unlike driver-driven systems, the contact force is not so large as to significantly drive the other gear. In driver-driven systems, the force applied by the driver gear turns the driven gear. That is, the driver gear meshes with (or interlocks with) the driven gear to mechanically drive the driven gear. While the force from the driver gear provides sealing at the interface point between the two teeth, this force is much higher than that necessary for sealing because this force must be sufficient enough to mechanically drive the driven gear to transfer the fluid at the desired flow and pressure.
In some exemplary embodiments, however, the gears 50, 70 of the pump 10 do not mechanically drive the other gear to any significant degree when the teeth 52, 72 form a seal in the contact area 78. Instead, the gears 50, 70 are rotatably driven independently such that the gear teeth 52, 72 do not grind against each other. That is, the gears 50, 70 are synchronously driven to provide contact but not to grind against each other. Specifically, rotation of the gears 50, 70 are synchronized at suitable rotation rates so that a tooth of the gear 50 contacts a tooth of the second gear 70 in the contact area 78 with sufficient enough force to provide substantial sealing, i.e., fluid leakage from the outlet port side to the inlet port side through the contact area 78 is substantially eliminated. However, unlike a driver-driven configuration, the contact force between the two gears is insufficient to have one gear mechanically drive the other to any significant degree. Precision control of the motors 41, 61, will ensure that the gear positions remain synchronized with respect to each other during operation.
In some embodiments, rotation of the gears 50, 70 is at least 99% synchronized, where 100% synchronized means that both gears 50, 70 are rotated at the same rpm. However, the synchronization percentage can be varied as long as substantial sealing is provided via the contact between the gear teeth of the two gears 50, 70. In exemplary embodiments, the synchronization rate can be in a range of 95.0% to 100% based on a clearance relationship between the gear teeth 52 and the gear teeth 72. In other exemplary embodiments, the synchronization rate is in a range of 99.0% to 100% based on a clearance relationship between the gear teeth 52 and the gear teeth 72, and in still other exemplary embodiments, the synchronization rate is in a range of 99.5% to 100% based on a clearance relationship between the gear teeth 52 and the gear teeth 72. Again, precision control of the motors 41, 61, will ensure that the gear positions remain synchronized with respect to each other during operation. By appropriately synchronizing the gears 50, 70, the gear teeth 52, 72 can provide substantial sealing, e.g., a backflow or leakage rate with a slip coefficient in a range of 5% or less. For example, for typical hydraulic fluid at about 120 deg. F., the slip coefficient can be can be 5% or less for pump pressures in a range of 3000 psi to 5000 psi, 3% or less for pump pressures in a range of 2000 psi to 3000 psi, 2% or less for pump pressures in a range of 1000 psi to 2000 psi, and 1% or less for pump pressures in a range up to 1000 psi. Of course, depending on the pump type, the synchronized contact can aid in pumping the fluid. For example, in certain internal-gear georotor configurations, the synchronized contact between the two fluid drivers also aids in pumping the fluid, which is trapped between teeth of opposing gears. In some exemplary embodiments, the gears 50, 70 are synchronized by appropriately synchronizing the motors 41, 61. Synchronization of multiple motors is known in the relevant art, thus detailed explanation is omitted here.
In an exemplary embodiment, the synchronizing of the gears 50, 70 provides one-sided contact between a tooth of the gear 50 and a tooth of the gear 70.
In
In some exemplary embodiments, the teeth of the respective gears 50, 70 are configured so as to not trap excessive fluid pressure between the teeth in the contact area 78. As illustrated in
As the pump 10 operates, there can be pressure spikes at the inlet and outlet ports (e.g., ports 22 and 24, respectively, in the example) of the pump due to, e.g., operation of an actuator (e.g., a hydraulic cylinder, a hydraulic motor, or another type of fluid operated actuator), the load that is being operated by the actuator, valves that are being operated in the system or for some other reason. These pressure spikes can cause damage to components in the fluid system. In some embodiments, the storage device 170 can be used to smooth out or dampen the pressure spikes. For example, the storage device 170 can be pressurized to a desire pressure and, as discussed above, connected to either the inlet port or the outlet port (or both with appropriate valves). When a pressure spike occurs at the port, the pressure spike is transmitted to the storage device 170, which then dampens the pressure spike due to the compressibility of the gas in the gas chamber 174. In addition, the fluid system in which the pump 10 operates may need to either add or remove fluid from the main fluid flow path of the fluid system due to, e.g., operation of the actuator. For example, when a hydraulic cylinder operates, the fluid volume in a closed-loop system may vary during operation because the extraction chamber volume and the retraction chamber volume may not be the same due to, e.g., the piston rod or for some other reason. In addition, changes in fluid temperature can also necessitate the addition or removal of fluid in a closed-loop system. In such cases, any extra fluid in the system will need to be stored and any fluid deficiency will need to be replenished. The storage device 170 can store and release the required amount of fluid for stable operation.
For example, in situations where the fluid system needs additional fluid during the operation of the pump 10, e.g., extracting a hydraulic cylinder that is attached the pump 10, the pressure of the inlet port, which is port 22 in the embodiment of
In the above discussed exemplary embodiments, both fluid drivers, including the prime movers and fluid displacement members, are integrated into a single pump casing 20. In addition, as described above, exemplary embodiments of the pump include an innovative configuration for fluid communication between at least one storage device and at least one port of the pump. Specifically, the pump can include one or more fluid paths through at least one shaft in the pump to provide fluid communication between at least one port of the pump and at least one fluid storage device that can be attached to the pump. This innovative fluid delivery system configuration of the pump and storage device of the present disclosure enables a compact arrangement that provides various advantages. First, the space or footprint occupied by the exemplary embodiments of the fluid delivery system discussed above is significantly reduced by integrating necessary components pump into a single pump casing and by integrating the fluid communication configuration between a storage device and a port of the pump, when compared to conventional pump systems. In addition, the total weight of the pump system is also reduced by removing unnecessary parts such as hoses or pipes used in conventional pump systems for fluid communication between a pump and a fluid storage device. In addition, this configuration can provide a cooling effect to the prime mover (e.g., motor) that gets heated during the pumping operation, especially at the center when motors are the prime movers. Further, since the pump of the present disclosure has a compact and modular arrangement, it can be easily installed, even at locations where conventional gear pumps and storage devices cannot be installed, and can be easily replaced.
In the above exemplary embodiments, both shafts 42, 62 include a through-passage configuration. However, in some exemplary embodiments, only one of the shafts has a through-passage configuration. For example,
Another single, flow-through shaft pump configuration is shown in
In the embodiment of
The configuration of flow-through shaft 662′ is different from that of the exemplary shafts described above because, unlike the other shafts, the shaft 662′ rotates. The flow-through shaft 662′ can be supported by bearings 151 on both ends. In the exemplary embodiment, the flow-through shaft 662′ has a rotary portion 155 that rotates with the motor rotor and a stationary portion 157 that is fixed to the motor casing. A coupling 153 can be provided between the rotary and stationary portions 155, 157 to allow fluid to travel between the rotary and stationary portions 155, 157 through the coupling 153 while the pump 610′ operates. In some embodiments, the coupling 153 can include one or more seals to prevent leakage. Of course, the stationary portion 157 can be part of the pump casing rather than a part of the flow-through shaft.
While the above exemplary embodiments illustrate only one storage device, exemplary embodiments of the present disclosure are not limited to one storage device and can have more than one storage device. For example, in an exemplary embodiment shown in
As seen in
The pump 710 also includes a motor 761 that includes shaft 762. The shaft 762 includes a through-passage 794. The through-passage 794 has a port 796 which is disposed in the fluid chamber 872 such that the through-passage 794 is in fluid communication with the fluid chamber 872. The other end of through-passage 794 is in fluid communication with a port of the pump 710 via a channel 792. Those skilled in the art will understand that through-passage 794 and channel 792 are similar to through-passage 184 and channel 192 discussed above. Accordingly, for brevity, detailed description of through-passage 794 and its characteristics and function within pump 710 are omitted.
The channels 782 and 792 can each be connected to the same port of the pump or to different ports. Connection to the same port can be beneficial in certain circumstances. For example, if one large storage device is impractical for any reason, it might be possible to split the storage capacity between two smaller storage devices that are mounted on opposite sides of the pump as illustrated in
In the exemplary embodiment shown in
In addition, the exemplary embodiments of the pump assembly of the present disclosure are not limited to the above exemplary embodiments of dual fluid driver (drive-drive) configurations. The flow-through shaft having the through-passage configuration can be used in other dual fluid driver pump configurations. For example, other configurations of a drive-drive system are discussed below in the context of exemplary embodiments of a pump assembly that do not have a flow-through shaft. However, based on the above disclosure, those skilled in the art would understand that the drive-drive configurations illustrated in
For example,
As seen in
As illustrated in
As discussed above, the gear body 950 can include cylindrical opening 951, which receives motor 941. In an exemplary embodiment, the fluid driver 940 can include outer support member 948 which aids in coupling the motor 941 to the gear 950 and in supporting the gear 950 on motor 941. The support member 948 can be, for example, a sleeve that is initially attached to either an outer casing of the motor 941 or an inner surface of the cylindrical opening 951. The sleeves can be attached by using an interference fit, a press fit, an adhesive, screws, bolts, a welding or soldering method, or other means that can attach the support members to the cylindrical openings. Similarly, the final coupling between the motor 941 and the gear 950 using the support member 948 can be by using an interference fit, a press fit, screws, bolts, adhesive, a welding or soldering method, or other means to attach the motors to the support members. The sleeve can be made to different thicknesses as desired to, e.g., facilitate the attachment of motors with different physical sizes to the gear 950 or vice versa. In addition, if the motor casing and the gear are made of materials that are not compatible, e.g., chemically or otherwise, the sleeve can be made of materials that are compatible with both the gear composition and the motor casing composition. In some embodiments, the support member 948 can be configured as a sacrificial piece. That is, support member 948 is configured to be the first to fail, e.g., due to excessive stresses, temperatures, or other causes of failure, in comparison to the gear 950 and motor 941. This allows for a more economic repair of the pump 910 in the event of failure. In some embodiments, the outer support member 948 is not a separate piece but an integral part of the casing for the motor 941 or part of the inner surface of the cylindrical opening 951 of the gear 950. In other embodiments, the motor 941 can support the gear 950 (and the plurality of gear teeth 952) on its outer surface without the need for the outer support member 948. For example, the motor casing can be directly coupled to the inner surface of the cylindrical opening 951 of the gear 950 by using an interference fit, a press fit, screws, bolts, an adhesive, a welding or soldering method, or other means to attach the motor casing to the cylindrical opening. In some embodiments, the outer casing of the motor 941 can be, e.g., machined, cast, or other means to shape the outer casing to form a shape of the gear teeth 952. In still other embodiments, the plurality of gear teeth 952 can be integrated with the rotor 946 such that the gear/rotor combination forms one rotary body.
As shown in
In the embodiment of
The shaft 962 includes a through-passage 1094. The through-passage 1094 permits fluid communication between fluid chamber 1072 and a port of the pump 910 via a channel 1092. Those skilled in the art will recognize that through-passage 1094 and channel 1092 perform similar functions as through-passage 194 and channel 192 discussed above with respect to pump 10. Accordingly, for brevity, a detailed description of through-passage 1094 and channel 1092 and their function within pump 910 are omitted.
In the above discussed exemplary embodiments, fluid driver 940, including electric motor 941 and gears 950, 970, are integrated into a single pump casing 920. Thus, similar to the dual fluid-driver exemplary embodiments, the configuration of the external gear pump 910 and storage device 970 of the present disclosure enables a compact arrangement that provides various advantages. First, the enclosed configuration means that there is less likelihood of contamination from outside the pump, e.g., through clearances in the shaft seals as in conventional pumps or from remotely disposed storage devices. Also, the space or footprint occupied by the gear pump and storage device is significantly reduced by integrating necessary components into an integrated fluid delivery system, when compared to conventional gear pump and storage device configurations. In addition, the total weight of the exemplary embodiments of the fluid delivery system is reduced by removing unnecessary parts such as a shaft that connects a motor to a pump, separate mountings for a motor/gear driver, and external hoses and pipes to connect the storage device. Further, since the fluid delivery system of the present disclosure has a compact and modular arrangement, it can be easily installed, even at locations where conventional gear pumps could not be installed, and can be easily replaced. Detailed description of the driver-driven pump operation is provided next.
As seen in
To prevent backflow, i.e., fluid leakage from the outlet side to the inlet side through the meshing area 978, the meshing between a tooth of the gear 950 and a tooth of the gear 970 in the meshing area 978 provides sealing against the backflow. Thus, along with driving gear 970, the meshing force from gear 950 will seal (or substantially seal) the backflow path, i.e., as understood by those skilled in the art, the fluid leakage from the outlet port side to the inlet port side through the meshing area 978 is substantially eliminated.
In addition, depending on the type of fluid displacement member, the meshing can be between any surface of at least one projection (e.g., bump, extension, bulge, protrusion, other similar structure or combinations thereof) on the first fluid displacement member and any surface of at least one projection (e.g., bump, extension, bulge, protrusion, other similar structure or combinations thereof) or an indent (e.g., cavity, depression, void or similar structure) on the second fluid displacement member. In some embodiments, at least one of the fluid displacement members can be made of or include a resilient material, e.g., rubber, an elastomeric material, or another resilient material, so that the meshing force provides a more positive sealing area.
In the embodiment of
Further, in the embodiments discussed above, the prime mover is disposed inside the fluid displacement member, i.e., motor 941 is disposed inside the cylinder opening 951 of gear 950. However, like the dual fluid driver (drive-drive) configurations discussed above, advantageous features of the inventive pump configuration are not limited to a configuration in which the prime mover is disposed within the body of the fluid displacement member. Other configurations also fall within the scope of the present disclosure. For example, in the context of an exemplary embodiment that does not have a flow-through shaft,
In the embodiments discussed above, the storage devices were described as pressurized vessels with a separating element (or piston) inside. However, in other embodiments, a different type of pressurized vessel may be used. For example, an accumulator, e.g. a hydraulic accumulator, may be used as a pressurized vessel. Accumulators are common components in fluid systems such as hydraulic operating and control systems. The accumulators store potential energy in the form of a compressed gas or spring, or by a raised weight to be used to exert a force against a relatively incompressible fluid. It is often used to store fluid under high pressure or to absorb excessive pressure increase. Thus, when a fluid system, e.g., a hydraulic system, demands a supply of fluid exceeding the supply capacity of a pump system, typically within a relatively short responsive time, pressurized fluid can be promptly provided according to a command of the system. In this way, operating pressure and/or flow of the fluid in the system do not drop below a required minimum value. However, storage devices other than an accumulator may be used as long as needed fluid can be provided from the storage device or storage devices to the pump and/or returned from the pump to the storage device or storage devices.
The accumulator may be a pressure accumulator. This type of accumulator may include a piston, diaphragm, bladder, or member. Typically, a contained volume of a suitable gas, a spring, or a weight is provided such that the pressure of hydraulic fluid in the accumulator increases as the quantity of hydraulic fluid stored in the accumulator increases. However, the type of accumulator in the present disclosure is not limited to the pressure accumulator. The type of accumulator can vary without departing from the scope of the present disclosure.
In addition, exemplary embodiments of the present disclosure are not limited to pump assemblies having pumps with integrated storage devices and flow-through shafts. For example, the storage device can be separate from the pump assembly if desired (e.g., if a large amount of storage is required) or may even be eliminated depending on the configuration of the system. In such cases the pump will not have an attached storage device and/or a flow-through shaft. For example,
As seen in
The fluid driver 1040 includes motor 1041 and a gear 1050. The motor 1041 is an outer-rotor motor design and is disposed in the body of gear 1050, which is disposed in the gear cavity 1086. The motor 1041 includes a rotor 1044 and a stator 1046. The gear 1050 includes a plurality of gear teeth 1052 extending radially outward from its gear body. It should be understood that those skilled in the art will recognize that fluid driver 1040 is similar to fluid driver 40 and that the configurations and functions of fluid driver 40, as discussed above, can be incorporated into fluid driver 1040. Accordingly, for brevity, fluid driver 1040 will not be discussed in detail except as necessary to describe this embodiment.
The fluid driver 1060 includes a motor 1061 and a gear 1070. The fluid driver 1060 is disposed next to fluid driver 1040 such that the respective gear teeth 1072, 1052 contact each other in a manner similar to the contact of gear teeth 52, 72 in contact area 78 discussed above with respect to pump 10. In this embodiment, motor 1061 is an inner-rotor motor design and is disposed in the motor cavity 1084. In this embodiment, the motor 1061 and the gear 1070 have a common shaft 1062. The rotor 1064 of motor 1061 is disposed radially between the shaft 1062 and the stator 1066. The stator 1066 is disposed radially outward of the rotor 1064 and surrounds the rotor 1064. The inner-rotor design means that the shaft 1062, which is connected to rotor 1064, rotates while the stator 1066 is fixedly connected to the casing 1020. In addition, gear 1070 is also connected to the shaft 1062. The shaft 1062 is supported by, for example, a bearing in the plate 1080 at one end 1088 and by a bearing in the plate 1082 at the other end 1090. In other embodiments, the shaft 1062 can be supported by bearing blocks that are fixedly connected to the casing 1020 rather than directly by bearings in the casing 1020. In addition, rather than a common shaft 1062, the motor 1061 and the gear 1070 can include their own shafts that are coupled together by known means.
As shown in
The motor 1061 is designed to fit into its cavity with sufficient tolerance between the motor casing and the pump casing 1020 so that fluid is prevented (or substantially prevented) from entering the cavity during operation. In addition, there is sufficient clearance between the motor casing and the gear 1070 for the gear 1070 to rotate freely but the clearance is such that the fluid can still be pumped efficiently. Thus, with respect to the fluid, in this embodiment, the motor casing is designed to perform the function of the appropriate portion of the pump casing walls of the embodiment of
In the above exemplary embodiment, the gear 1070 is shown as being spaced apart from the motor 1061 along the axial direction of the shaft 1062. However, other configurations fall within the scope of the present disclosure. For example, the gear 1070 and motor 1061 can be completely separated from each other (e.g., without a common shaft), partially overlapping with each other, positioned side-by-side, on top of each other, or offset from each other. Thus, the present disclosure covers all of the above-discussed positional relationships and any other variations of a relatively proximate positional relationship between a gear and a motor inside the casing 1020. In addition, in some exemplary embodiments, motor 1061 can be an outer-rotor motor design that is appropriately configured to rotate the gear 1070.
Further, in the exemplary embodiment described above, the torque of the motor 1061 is transmitted to the gear 1070 via the shaft 1062. However, the means for transmitting torque (or power) from a motor to a gear is not limited to a shaft, e.g., the shaft 1062 in the above-described exemplary embodiment. Instead, any combination of power transmission devices, e.g., shafts, sub-shafts, belts, chains, couplings, gears, connection rods, cams, or other power transmission devices, can be used without departing from the spirit of the present disclosure.
The fluid drivers 1140, 1160 respectively include motors 1141, 1161 and gears 1150, 1170. The motors 1141, 1161 are of an inner-rotor design and are respectively disposed in motor cavities 1184, 1184′. The motor 1141 and gear 1150 of the fluid driver 1140 have a common shaft 1142 and the motor 1161 and gear 1170 of the fluid driver 1160 have a common shaft 1162. The motors 1141, 1161 respectively include rotors 1144, 1164 and stators 1146, 1166, and the gears 1150, 1170 respectively include a plurality of gear teeth 1152, 1172 extending radially outward from the respective gear bodies. The fluid driver 1140 is disposed next to fluid driver 1160 such that the respective gear teeth 1152, 1172 contact each other in a manner similar to the contact of gear teeth 52, 72 in contact area 78 discussed above with respect to pump 10. Bearings 1195 and 1195′ can be respectively disposed between motors 1141, 1161 and gears 1150, 1170. The bearings 1195 and 1195′ are similar in design and function to bearing 1095 discussed above. It should be understood that those skilled in the art will recognize that the fluid drivers 1140, 1160 are similar to fluid driver 1060 and that the configurations and functions of the fluid driver 1060, discussed above, can be incorporated into the fluid drivers 1140, 1160 within pump 1110. Thus, for brevity, fluid drivers 1140, 1160 will not be discussed in detail. Similarly, the operation of pump 1110 is similar to that of pump 10 and thus, for brevity, will not be further discussed. In addition, like fluid driver 1060, the means for transmitting torque (or power) from the motor to the gear is not limited to a shaft. Instead, any combination of power transmission devices, for example, shafts, sub-shafts, belts, chains, couplings, gears, connection rods, cams, or other power transmission devices can be used without departing from the spirit of the present disclosure. In addition, in some exemplary embodiments, motors 1141, 1161 can be outer-rotor motor designs that are appropriately configured to respectively rotate the gears 1150, 1170.
The fluid driver 1240 includes motor 1241 and a gear 1250. The motor 1241 is an outer-rotor motor design and is disposed in the body of gear 1250, which is disposed in the internal volume. The motor 1241 includes a rotor 1244 and a stator 1246. The gear 1250 includes a plurality of gear teeth 1252 extending radially outward from its gear body. It should be understood that those skilled in the art will recognize that fluid driver 1240 is similar to fluid driver 40 and that the configurations and functions of fluid driver 40, as discussed above, can be incorporated into fluid driver 1240. Accordingly, for brevity, fluid driver 1240 will not be discussed in detail except as necessary to describe this embodiment.
The fluid driver 1260 includes a motor 1261 and a gear 1270. The fluid driver 1260 is disposed next to fluid driver 1240 such that the respective gear teeth 1272, 1252 contact each other in a manner similar to the contact of gear teeth 52, 72 in contact area 78 discussed above with respect to pump 10. In this embodiment, motor 1261 is an inner-rotor motor design and, as seen in
As shown in
In the above embodiment gear 1270 is shown spaced apart from the motor 1261 along the axial direction of the shafts 1262 and 1262′ (i.e., spaced apart but axially aligned). However, other configurations can fall within the scope of the present disclosure. For example, the gear 1270 and motor 1261 can be positioned side-by-side, on top of each other, or offset from each other. Thus, the present disclosure covers all of the above-discussed positional relationships and any other variations of a relatively proximate positional relationship between a gear and a motor outside the casing 1220. In addition, in some exemplary embodiments, motor 1261 can be an outer-rotor motor design that is appropriately configured to rotate the gear 1270.
Further, in the exemplary embodiment described above, the torque of the motor 1261 is transmitted to the gear 1270 via the shafts 1262, 1262′. However, the means for transmitting torque (or power) from a motor to a gear is not limited to shafts. Instead, any combination of power transmission devices, e.g., shafts, sub-shafts, belts, chains, couplings, gears, connection rods, cams, or other power transmission devices, can be used without departing from the spirit of the present disclosure. In addition, the motor housing 1287 can include a vibration isolator (not shown) between the casing 1220 and the motor housing 1287. Further, the motor housing 1287 mounting is not limited to that illustrated in
The fluid driver 1340 includes a motor 1341 and a gear 1350. In this embodiment, motor 1341 is an inner-rotor motor design and, as seen in
In addition, the gear 1350 and motor 1341 can be positioned side-by-side, on top of each other, or offset from each other. Thus, the present disclosure covers all of the above-discussed positional relationships and any other variations of a relatively proximate positional relationship between a gear and a motor outside the casing 1320. Also, in some exemplary embodiments, motor 1341 can be an outer-rotor motor design that are appropriately configured to rotate the gear 1350. Further, the means for transmitting torque (or power) from a motor to a gear is not limited to shafts. Instead, any combination of power transmission devices, e.g., shafts, sub-shafts, belts, chains, couplings, gears, connection rods, cams, or other power transmission devices, can be used without departing from the spirit of the present disclosure. In addition, the motor housing 1387 can include a vibration isolator (not shown) between the casing 1320 and the motor housing 1387. Further, the motor housing 1387 mounting is not limited to that illustrated in
The fluid driver 1360 includes a motor 1361 and a gear 1370. The fluid driver 1360 is disposed next to fluid driver 1340 such that the respective gear teeth 1372, 1352 contact each other in a manner similar to the contact of gear teeth 52, 72 in contact area 128 discussed above with respect to pump 10. In this embodiment, motor 1361 is an inner-rotor motor design and is disposed in the motor cavity 1384. In this embodiment, the motor 1361 and the gear 1370 have a common shaft 1362. The rotor 1364 of motor 1361 is disposed radially between the shaft 1362 and the stator 1366. The stator 1366 is disposed radially outward of the rotor 1364 and surrounds the rotor 1364. Bearing 1395 can be disposed between motor 1361 and gear 1370. The bearing 1395 is similar in design and function to bearing 1095 discussed above. The inner-rotor design means that the shaft 1362, which is connected to rotor 1364, rotates while the stator 1366 is fixedly connected to the casing 1320. In addition, gear 1370 is also connected to the shaft 1362. It should be understood that those skilled in the art will recognize that the fluid driver 1360 is similar to fluid driver 1060 and that the configurations and functions of fluid driver 1060, as discussed above, can be incorporated into fluid driver 1360. Accordingly, for brevity, fluid driver 1360 will not be discussed in detail except as necessary to describe this embodiment. Also, in some exemplary embodiments, motor 1361 can be an outer-rotor motor design that is appropriately configured to rotate the gear 1370. In addition, it should be understood that those skilled in the art will recognize that the operation of pump 1310, including fluid drivers 1340, 1360, will be similar to that of pump 10 and thus, for brevity, will not be further discussed. In addition, the means for transmitting torque (or power) from the motor to the gear is not limited to a shaft. Instead, any combination of power transmission devices, for example, shafts, sub-shafts, belts, chains, couplings, gears, connection rods, cams, or other power transmission devices can be used without departing from the spirit of the present disclosure.
The fluid drivers 1540, 1560 respectively include motors 1541, 1561 and gears 1550, 1570. The fluid driver 1540 is disposed next to fluid driver 1560 such that the respective gear teeth 1552, 1572 contact each other in a manner similar to the contact of gear teeth 52, 72 in contact area 78 discussed above with respect to pump 10. In this embodiment, motors 1541, 1561 are of an inner-rotor motor design and, as seen in
In an exemplary embodiment, the motor housing 1587 can include a vibration isolator (not shown) between the plate 1580 and the motor housing 1587. In the exemplary embodiment above, the motor 1541 and the motor 1561 are disposed in the same motor housing 1587. However, in other embodiments, the motor 1541 and the motor 1561 can be disposed in separate housings. Further, the motor housing 1587 mounting and motor locations are not limited to that illustrated in
In addition to the non-flow through shaft drive-drive configurations of
The motor 1641 is designed to fit into its cavity 1685 with sufficient tolerance between the motor casing and the pump casing 1620 so that fluid is prevented (or substantially prevented) from entering the cavity 1685 during operation. In addition, there is sufficient clearance between the motor casing and the gear 1650 for the gear 1650 to rotate freely but the clearance is such that the fluid can still be pumped efficiently. Thus, with respect to the fluid, in this embodiment, the motor casing is designed to perform the function of the appropriate portion of the pump casing walls of the embodiment of
In the above exemplary embodiment, the gear 1650 is shown as being spaced apart from the motor 1641 along the axial direction of the shaft 1642. However, other configurations fall within the scope of the present disclosure. For example, the gear 1650 and motor 1641 can be completely separated from each other (e.g., without a common shaft), partially overlapping with each other, positioned side-by-side, on top of each other, or offset from each other. Thus, the present disclosure covers all of the above-discussed positional relationships and any other variations of a relatively proximate positional relationship between a gear and a motor inside the casing 1620. In addition, in some exemplary embodiments, motor 1641 can be an outer-rotor motor design that is appropriately configured to rotate the gear 1650.
Further, in the exemplary embodiment described above, the torque of the motor 1641 is transmitted to the gear 1650 via the shaft 1642. However, the means for transmitting torque (or power) from a motor to a gear is not limited to a shaft, e.g., the shaft 1642 in the above-described exemplary embodiment. Instead, any combination of power transmission devices, e.g., shafts, sub-shafts, belts, chains, couplings, gears, connection rods, cams, or other power transmission devices, can be used without departing from the spirit of the present disclosure. As discussed above, although the exemplary embodiments of
One difference between pump assembly 1710 and pump assembly 2 is that, in pump assembly 1710, the valve assemblies that isolate the pump assembly 1710 are disposed internal to the casing 1720 of the pump assembly 1710. In addition, in some exemplary embodiments, sensor assemblies that measure pump and system parameters can also be disposed internal to the casing of the pump assembly 1710. For example, as seen in
The valve assemblies 222 and 242 are disposed in the fluid path of pump assembly 1710 such that the valves 222B and 242B, when operated, fluidly isolate pump assembly 1710 from the fluid system or permit fluid communication with the fluid system. In the exemplary embodiment of
The pump assembly 1710 can also include sensor assemblies 228 and 248 disposed within the casing wall 1721 of the pump assembly 1710. However, at least a portion of or the entirety of the sensor assemblies 228 and 248 can be disposed the internal volume 1722. The sensor assemblies 228 and 248 can monitor pump and/or system parameters (e.g., measured pressure, temperature, flow rate or other system parameters). For example, as shown in
In some embodiments, the lock valves 222, 242 are normally closed solenoid controlled valves which return to a closed position when the solenoid is de-energized. Thus, these valves can return to a closed position in the event of abnormal or emergent operations, for example, detection of excessive pressure, power outage, failure of an operating system, failure of a motor, failure of a pressure transducer, or activation of an emergency button. Accordingly, the flow of fluid is prevented from entering or exiting the pump assembly 1710, thereby ensuring safety during emergent events. Because the valve assemblies 222, 242, sensor assemblies 228, 248, and corresponding connectors are all contained in the casing and/or the internal volume of the pump 1710, the pump assembly 1710 makes for a compact configuration and reduces potential sources of contamination in the fluid system.
As discussed above, in some embodiments, the valves 222B, 242B can be lock valves (or shutoff valves) that are either fully open or fully closed (i.e. switchable between a fully open state and a fully closed state) and actuated by the respective solenoids 222A and 242A. In other embodiments, the valves 222B, 242B can be set to intermediate positions between 0% and 100%. It should be understood however that, while the valves 222B, 242B can be set to a desired position at the start and end of a given hydraulic system operation, the valves are not used to control the flow or pressure during the operation. That is, during normal operation, the valves 222B, 242B will remain at the set position during a given operation, e.g., at full open or another desired position at the start of the operation. During the hydraulic system operation, in some embodiments, the control unit 266 will control the speed and/or torque of the motor or motors in fluid driver assembly 1730 to exclusively adjust the flow and/or pressure in the hydraulic system. In this way, the complexity of conventional systems that use, e.g., directional flow valves and variable-flow piston pumps can be eliminated, which will also provide a more reliable system in terms of maintenance and control.
In the system of
The linear system 1700 can include one or more process sensors therein. For example, as discussed above, pump assembly 1710 can include sensor assemblies 228 and 248 and, alternatively or additionally, sensor assemblies 297 and 298 can be included in the system. Each of the sensor assemblies 228, 248, 297, 298 can include one or more sensors to monitor the system operational parameters. The sensor assemblies 228, 248, 297, 298 can communicate with the control unit 266 and/or drive unit 295. Each sensor assembly 228, 248, 297, 298 can include at least one of a pressure transducer, a temperature transducer, and a flow transducer (i.e., any combination of the transducers therein). Signals from the sensor assemblies 228, 248, 297, 298 can be used by the control unit 266 and/or drive unit 295 for monitoring and for control purposes. In some embodiments sensor assemblies 228 and 248 can be configured to monitor the performance of fluid driver assembly 1730, e.g., the mechanical performance, while sensor assemblies 297, 298 can be configured to monitor general system parameters and/or performance of the hydraulic cylinder 3. The status of each valve assembly 222, 242 (e.g., the appropriate operational status—open or closed, percent opening, or some other valve status indication) and the process data measured by the sensors in sensor assemblies 228, 248, 297, 298 (e.g., measured pressure, temperature, flow rate or other system parameters) may be communicated to the drive unit 295 via the respective communication connections 302-305.
As discussed above, the fluid driver assembly 1730 includes one or more motors depending on the configuration of the fluid driver assembly 1730. The motor or motors are controlled by the control unit 266 via the drive unit 295 using communication connection 301. In some embodiments, the functions of drive unit 295 can be incorporated into one or both motors (if the pump has two motors) and/or the control unit 266 such that the control unit 266 communicates directly with one or both motors. In addition, the valve assemblies 222, 242 can also be controlled (e.g., open/close) by the control unit 266 via the drive unit 295 using communication connections 301, 302, and 303. In some embodiments, the functions of drive unit 295 can be incorporated into the valve assemblies 222, 242 and/or control unit 266 such that the control unit 266 communicates directly with valve assemblies 222, 242. The drive unit 295 can also process the communications between the control unit 266 and the sensor assemblies 228, 248, 297, 298 using communication connections 232, 252, 304 and 305. In some embodiment, the control unit 266 can be set up to communicate directly with the sensor assemblies 228, 248, 297 and/or 298. The data from the sensors can be used by the control unit 266 and/or drive unit 295 to control the motor(s) and/or the valve assemblies 222, 242. For example, based on the process data measured by the sensors in sensor assemblies 228, 248, 297, 298, the control unit 266 can provide command signals to the valve assemblies to, e.g., open/close lock valves in the valve assemblies 222, 242 (or move the valves to an intermediate opening) in addition to controlling a speed and/or torque of the motor(s).
The drive unit 295 includes hardware and/or software that interprets the command signals from the control unit 266 and sends the appropriate demand signals to the motor(s) and/or valve assemblies 222, 242. For example, the drive unit 295 can include pump and/or motor curves that are specific to the fluid driver assembly 1730 such that command signals from the control unit 266 will be converted to appropriate speed/torque demand signals to the fluid driver assembly 1730 based on the design of the fluid driver assembly 1730. Similarly, the drive unit 295 can include valve and/or actuator curves that are specific to the valve assemblies 222, 242 and the command signals from the control unit 266 will be converted to the appropriate demand signals based on the type of valve. The pump/motor and/or the valve curves can be implemented in hardware and/or software, e.g., in the form of hardwire circuits, software algorithms and formulas, or some other hardware and/or software system that appropriately converts the demand signals to control the pump/motor and/or the valve. In some embodiments, the drive unit 295 can include application specific hardware circuits and/or software (e.g., algorithms) to control the motor(s) and/or valve assemblies 222, 242.
The control unit 266 can receive feedback data from one or both motors (if the pump has two motors). For example, the control unit 266 can receive speed or frequency values, torque values, current and voltage values, or other values related to the operation of the motor(s). In addition, the control unit 266 can receive feedback data from the valve assemblies 222, 242. For example, the control unit 266 can receive the open and close status of the lock valves 222B, 242B. In some embodiments, the lock valves 222B, 242B can have a percent opening indication instead of or in addition to an open/close indication to e.g., provide status of a partially open valve. Further, the control unit 266 can receive feedback of process parameters such as pressure, temperature, flow, or some other process parameter. As discussed above, each sensor assembly 228, 248, 297, 298 can have one or more sensors to measure process parameters such as pressure, temperature, and flow rate of the hydraulic fluid. The illustrated sensor assemblies 297, 298 are shown disposed next to the hydraulic cylinder 3. However, the sensor assemblies 297 and 298 are not limited to these locations. Alternatively, or in addition to sensor assemblies 297, 298, the system 1700 can have other sensors throughout the system to measure process parameters such as, e.g., pressure, temperature, flow, or some other process parameter. While the range and accuracy of the sensors will be determined by the specific application, it is contemplated that hydraulic system application with have pressure transducers that range from 0 to 5000 psi with the accuracy of +/−0.5%. These transducers can convert the measured pressure to an electrical output, e.g., a voltage ranging from 1 to 5 DC voltages. Similarly, temperature transducers can range from −4 deg. F. to 300 deg. F., and flow transducers can range from 0 gallons per minute (gpm) to 160 gpm with an accuracy of +/−1% of reading. However, the type, range and accuracy of the transducers in the present disclosure are not limited to the transducers discussed above, and the type, range and/or the accuracy of the transducers can vary without departing from the scope of the present disclosure.
Although the drive unit 295 and control unit 266 are shown as separate controllers in
The control unit 266 may receive inputs from an operator's input unit 276. Using the input unit 276, the operator can manually control the system or select pre-programmed routines. For example, the operator can select a mode of operation for the system such as flow (or speed) mode, pressure (or torque) mode, or a balanced mode. Flow or speed mode may be utilized for an operation where relatively fast retraction or extraction of the piston rod 6 is requested with relatively low torque requirement. Conversely, a pressure or torque mode may be utilized for an operation where relatively slow retraction or extraction of the piston rod 6 is requested with a relatively high torque requirement. Based on the mode of operation selected, the control scheme for controlling the motor(s) can be different.
As discussed above, in some embodiments, the valve assemblies 222, 242 can include lock valves that are designed to be either fully open or fully closed. In such systems, the control unit 266/drive unit 295 will fully open the valves and, in some embodiments, check for the open feedback prior to starting the motor(s). During normal operation, the valves 222B, 242B can be at 100% open or some other desired position by, e.g., energizing the respective solenoids 222A and 242A, and the control unit 266/drive unit 295 controls the operation of the motor(s) to maintain the flow and/or pressure at the operational set point. The operational set point can be determined or calculated based on a desired and/or an appropriate set point for a given mode of operation. Upon shutdown or abnormal operation, the motor(s) are shut down and the valves 222B, 242B are closed or moved to some other desired position, e.g., by de-energizing the respective solenoids 222A and 242A. During a normal shut down, the hydraulic pressure in the system may be allowed to drop before the valves are closed. However, in some abnormal operating conditions, based on safety protocol routines, the valves may be closed immediately after or substantially simultaneously with the motor(s) being turned off in order to trap the pressure in the system. For example, in some abnormal conditions, it might be safer to lock the hydraulic cylinder 3 in place by trapping the pressure on the extraction chamber 8 and the retraction chamber 7.
In the exemplary system of
When the control unit 266 receives a command to retract the cylinder rod 6, for example in response to an operator's command, the control unit 266 controls the speed and/or torque of the pump 10 to transfer pressurized fluid from the extraction chamber 8 to the retraction chamber 7. That is, fluid driver assembly 1730 pumps fluid from port A to port B. In this way, the pressurized fluid in the extraction chamber 8 is drawn, via the hydraulic line 268, into the port A of the pump assembly 1710 and carried to the port B and further to the retraction chamber 7 via the hydraulic line 268. By transferring fluid and increasing the pressure in the retraction chamber 7, the piston rod 6 is retracted. During this operation of the pump 1710, the pressure in the port B side of the pump 1710 can become higher than that of the storage device (e.g., pressurized vessel) 1770. Thus, a portion of the fluid carried from the extraction chamber 8 is replenished back to the storage device 1770.
The control unit 266 that controls the linear system 1700 can have multiple operational modes. For example, a speed/flow mode, a torque/pressure mode, or a combination of both. A speed/flow mode may be utilized for an operation where relatively fast retraction or extraction of the piston rod 6 is requested with relatively low torque requirement. Conversely, a torque/pressure mode may be utilized for an operation where relatively slow retraction or extraction of the piston rod 6 is requested with a relatively high torque requirement. Operation of the linear system 1700 will be discussed further below.
Preferably, the motor(s) of fluid driver assembly 1730 are variable speed/variable torque and bi-directional. Depending on the mode of operation, e.g. as set by the operator or as determined by the system based on the application (e.g., boom application), the flow and/or pressure of the system can be controlled to an operational set-point value by controlling either the speed or torque of the motor. For example, in flow (or speed) mode operation, the control unit 266/drive unit 295 controls the flow in the system by controlling the speed of the motor(s). When the system is in pressure (or torque) mode operation, the control unit 266/drive unit 295 controls the pressure at a desired point in the system, e.g., at the chambers 7, 8, by adjusting the torque of the hydraulic pump motor(s). When the system is in a balanced mode of operation, the control unit 266/drive unit 295 takes both the system's pressure and hydraulic flow rate into account when controlling the motor(s). Because the pump is not run continuously at a high rpm as in conventional systems, the temperature of the fluid remains relatively low thereby eliminating the need for a large fluid reservoir. In some embodiments, in each of these modes, the speed and/or torque of the fluid driver assembly 1730 can be controlled to exclusively adjust the flow and/or pressure in the system, i.e., without the aid of another flow control device, to the operational set point.
The pressure/torque mode operation can be used to ensure that either the extraction chamber 8 or retraction chamber 7 of the hydraulic cylinder 3 is maintained at a desired pressure (or any other point in the hydraulic system). In pressure/torque mode operation, the power to the hydraulic pump motor(s) is determined based on the system application requirements using criteria such as maximizing the torque of the motors. If the hydraulic pressure is less than a predetermined set-point at the extraction chamber 8 side (e.g., at the location of sensor assembly 248 and/or 297) of the hydraulic pump assembly 1710, the control unit 266/drive unit 295 will increase the hydraulic pump's motor current (and thus the torque of the hydraulic motor(s)) to increase the hydraulic pressure. If the pressure at sensor assembly 297 is less than the required pressure based on the operational set point, the control unit 266/drive unit 295 will decrease the current of motor(s) (and thus the torque) to reduce the hydraulic pressure. While the pressure at sensor assembly 297 is used in the above-discussed exemplary embodiment, pressure mode operation is not limited to measuring the pressure at a single location. Instead, the control unit 266/drive unit 295 can receive pressure feedback signals from multiple locations in the system for control.
In flow/speed mode operation, the power to the motor(s) is determined based on the system application requirements using criteria such as how fast the motor(s) ramp to the desired speed and how precisely the motor speeds can be controlled. Because the fluid flow rate is proportional to the motor speed and the fluid flow rate determines the travel speed of the hydraulic cylinder 3, the control unit 266 can be configured to control the travel speed of the hydraulic cylinder 3 based on a control scheme that uses the motor speed, the flow rate, or some combination of the two. That is, when a specific response time of the hydraulic cylinder 3 is required, the control unit 266/drive unit 295 can control the motor(s) to achieve a predetermined speed and/or a predetermined hydraulic flow rate that corresponds to the desired response time for the hydraulic cylinder 3. For example, the control unit 266/drive unit 295 can be set up with algorithms, look-up tables, or some other type of hardware and/or software functions to correlate the speed of the hydraulic cylinder 3 to the speed of the fluid driver assembly 1730 and/or the flow of the hydraulic fluid. Thus, if the system requires that the hydraulic cylinder 3 move from position X to position Y (see
If the control scheme uses the flow rate, the control unit 266/drive unit 295 can receive a feedback signal from a flow sensor, e.g., a flow sensor in one or all of sensor assemblies 228, 248, 297, 298, to determine the actual flow in the system. The flow in the system may be determined by measuring, e.g., the differential pressure across two points in the system, the signals from an ultrasonic flow meter, the frequency signal from a turbine flow meter, or by using some other type of flow sensor or instrument. Thus, in systems where the control scheme uses the flow rate, the control unit 266/drive unit 295 can control the flow output of the fluid driver assembly 1730 to a predetermined flow set-point value that corresponds to the desired travel speed of the hydraulic cylinder 3.
Similarly, if the control scheme uses the motor speed, the control unit 266/drive unit 295 can receive speed feedback signals from the fluid driver(s) of the fluid driver assembly 1730. For example, the actual speed of the motor(s) can be measured by sensing the rotation of the pump gears. For example, the fluid driver assembly 1730 can include a magnetic sensor (not shown) that senses the gear teeth as they rotate. Alternatively, or in addition to the magnetic sensor (not shown), one or more teeth can include magnets that are sensed by a pickup located either internal or external to the hydraulic pump casing. Thus, in systems where the control scheme uses the flow rate, the control unit 266/drive unit 295 can control the actual speed of the fluid driver assembly 1730 to a predetermined speed set-point that corresponds to the desired travel speed of the hydraulic cylinder 3.
Alternatively, or in addition to the controls described above, the speed of the hydraulic cylinder 3 can be measured directly and compared to a desired travel speed set-point to control the speed of motor(s).
In some embodiments, for drive-drive configurations, the control unit 266/drive unit 295 (or some other controller) can be configured such that when one of prime movers fails, the pump will operate in a driver-driven configuration to operate the system, e.g., operate the system for a limited time period to safely shutdown the system. That is, the system will go from a configuration where the fluid drivers are independently driven with synchronous contact between the fluid drivers to a configuration where the remaining operative motor drives the corresponding fluid driver (e.g., gear), which in turn meshes with the other fluid driver (e.g., gear). Thus, the control unit 266/drive unit 295 can have a normal mode of operation where the fluid drivers 40, 60 of the fluid driver assembly 1730 are independently driven by the motors 41 and 61 so as to synchronize contact between the respective gears of fluid drivers 40 and 60, and a fail-safe mode where the fluid driver assembly 1730 is operated in a driver-driven configuration using the operative motor and shutting down the non-operational motor. “Non-operational” means that the motor is inoperative or operating outside of established safety and/or operational guidelines and/or procedures. The guidelines and procedures can be established, e.g., by the motor manufacturer based on current and/or power limits, temperature limits, vibration limits or some other performance limit of the motor. Alternatively, or in addition to the manufacturer's guidelines and/or procedures, other guidelines and procedures can be established based on limits specific to the particular application, e.g., limits based on pump flow and pressure curves. The fail-safe mode operation may eliminate or reduce the hydraulic system's downtime caused by failure of one of the electric motors 41, 61 until the non-operational motor is repaired or replaced.
Inoperativeness of a motor (or failure of a motor) may be detected in various ways. For example, if there are abnormal current readings by one or both of the motors or if there is a difference in current readings between the two motors, it can be a sign of motor problems. Similarly, a difference in speed feedback (or no feedback—zero value) of a motor compared to the demand signal and/or a difference in rpm readings between the two motors can also be a sign of motor problems. Of course, other indications such as responsiveness of a motor in comparison to a predetermined limit or limits (e.g., comparison to a desired set point, an upper and/or a lower limit), temperature of a motor, vibration of a motor or some other performance criteria of the motor can also be used to determine if a motor is failing and whether to switch the system from normal mode of operation to a fail-safe mode of operation. The switch from normal mode to fail-safe mode can be done manually by the operator based on indications provided to the operator by the control unit 266. Alternatively or in addition to the manual option, the control unit 266 can be configured to automatically switch from normal mode to fail-safe mode based on a determination that a prime mover, e.g., a motor, is non-operational, i.e., operating abnormally, according to predetermined criteria, as discussed above. Depending on the type of operation, the control unit 266 can immediately shut down the system or let the system run at a reduced load limit for a predetermined period of time. For example, if a motor fails when the boom of an excavator is on the ground, the control unit 266 will immediately shut down the system prior to operator attempting to lift a load. However, if the boom is in the air and is carrying a load, the control unit 266, after providing an alarm to the operator, will allow operation in driver-driven mode for a predetermined amount of time for the operator to safely bring down the load. In some embodiments, the control unit 266 may allow operation in a driver-driven for an indefinite period of time but at a reduced load (e.g., 50-75% of full load power as compared to the normal mode of operation).
As discussed above, the control unit 266/drive unit 295 can include motor and/or valve curves. In addition, the hydraulic cylinder 3 can also have characteristic curves that describe the operational characteristics of the cylinder, e.g., curves that correlate pressure/flow with travel speed/position. The characteristic curves of the motor(s) of fluid driver assembly 1730, valve assemblies 222, 242, and the hydraulic cylinder 3 can be stored in memory, e.g. RAM, ROM, EPROM, or some other type of storage device in the form of look-up tables, formulas, algorithms, or some other type of software implementation in the control unit 266, drive unit 295, or some other storage that is accessible to the control unit 266/drive unit 295 (e.g., in the fluid driver(s) of fluid driver assembly 1730, valve assemblies 222, 242, and/or the hydraulic cylinder 3). The control unit 266/drive unit 295 can then use the characteristic curves to precisely control the motor(s).
The linear actuator assemblies discussed above can be a component in systems, e.g., industrial machines, in which one structural element is moved or translated relative to another structural element. In some embodiment, the extraction and retraction of the linear actuator, e.g., hydraulic cylinder, will provide a linear or telescoping movement between the two structural elements, e.g., a hydraulic car lift. In other embodiments, where the two structures are pivotally attached, the linear actuator can provide a rotational or turning movement of one structure relative to the other structure. For example,
In the boom structure of 2301, each of the linear actuator assemblies is mounted between two structural elements such that operation of the linear actuator assembly will rotate one of the structural element relative to the other around a pivot point. For example, one end of the bucket actuator assembly 2307 can be mounted at a boom mounting structure 2309 on the boom 2303 and the other end can be mounted at a bucket mounting structure 2308 on the bucket 2304. The attachment to each mounting structure 2309 and 2303 is such that the ends of the bucket actuator assembly 2307 are free to move rotationally. The bucket 2304 and the boom 2303 are pivotally attached at pivot point 2304A. Thus, extraction and retraction of bucket actuator assembly 2307 will rotate bucket 2304 relative to boom 2303 around pivot point 2304A. Various mounting structures for linear actuators (e.g., other types of mounting structures providing relative rotational movement, mounting structures providing linear movement, and mounting structure providing combinations of rotational and linear movements) are known in the art, and thus a detailed explanation other types of mounting structures is omitted here.
Each actuator assembly 2305, 2306, 2307 may include a hydraulic pump assembly and a hydraulic cylinder and can be any of the drive-drive or driver-driven linear actuator assemblies discussed above. In the exemplary embodiment of the boom structure 2301, the respective hydraulic pump assemblies 2311, 2312, 2313 for actuator assemblies 2305, 2306, 2307 are mounted on the top of the corresponding hydraulic cylinder housings. However, in other embodiments, the hydraulic pump assemblies may be mounted on a different location, for example at the rear end of the cylinder housing 4 as illustrated in
In addition to linear actuator assemblies, the boom structure 2301 can also include an auxiliary pump assembly 2310 to provide hydraulic fluid to other hydraulic device such as, e.g., portable tools, i.e., for operations other than boom operation. For example, a work tool such as a jackhammer may be connected to the auxiliary pump assembly 2310 for drilling operation. The configuration of auxiliary pump assembly 2310 can be any of the drive-drive or driver-driven pump assemblies discussed above. Each actuator assembly 2305, 2306, 2307 and the auxiliary pump 2310 can be connected, via wires (not shown), to a generator (not shown) mounted on the excavator such that the electric motor(s) of each actuator and the auxiliary pump can be powered by the generator. In addition, the actuators 2305, 2306, 2307 and the auxiliary pump 2310 can be connected, via wires (not shown), to a controller (not shown) to control operations as described above with respect to control unit 266/drive unit 295. Because each of the linear actuator assemblies are closed-loop hydraulic systems, the excavator using the boom structure 2301 does not require a central hydraulic storage tank or a large central hydraulic pump, including associated flow control devices such as a variable displacement pump or directional flow control valves. In addition, hydraulic hoses and pipes do not have to be run to each actuator as in conventional systems. Accordingly, an excavator or other industrial machine using the linear actuator assemblies of the present disclosure will not only be less complex and lighter, but the potential sources of contamination into the hydraulic system will be greatly reduced.
The articulated boom structure 301 with the linear actuators 305, 306, 307 of an excavator described above is only for illustrative purpose and application of the linear actuator 1 of the present disclosure is not limited to operating the boom structure of an excavator. For example, the linear actuator 1 of the present disclosure can be applied to various other machinery such as backhoes, cranes, skid-steer loaders, and wheel loaders.
Although the above drive-drive and driver-driven embodiments were described with respect to an external gear pump arrangement with spur gears having gear teeth, it should be understood that those skilled in the art will readily recognize that the concepts, functions, and features described below can be readily adapted to external gear pumps with other gear configurations (helical gears, herringbone gears, or other gear teeth configurations that can be adapted to drive fluid), internal gear pumps with various gear configurations, to pumps having more than two prime movers, to prime movers other than electric motors, e.g., hydraulic motors or other fluid-driven motors, inter-combustion, gas or other type of engines or other similar devices that can drive a fluid displacement member, and to fluid displacement members other than an external gear with gear teeth, e.g., internal gear with gear teeth, a hub (e.g. a disk, cylinder, other similar component) with projections (e.g. bumps, extensions, bulges, protrusions, other similar structures or combinations thereof), a hub (e.g. a disk, cylinder, or other similar component) with indents (e.g., cavities, depressions, voids or other similar structures), a gear body with lobes, or other similar structures that can displace fluid when driven. Accordingly, for brevity, detailed description of the various pump configurations are omitted. In addition, those skilled in the art will recognize that, depending on the type of pump, the synchronizing contact (drive-drive) or meshing (driver-driven) can aid in the pumping of the fluid instead of or in addition to sealing a reverse flow path. For example, in certain internal-gear georotor configurations, the synchronized contact or meshing between the two fluid displacement members also aids in pumping the fluid, which is trapped between teeth of opposing gears. Further, while the above embodiments have fluid displacement members with an external gear configuration, those skilled in the art will recognize that, depending on the type of fluid displacement member, the synchronized contact or meshing is not limited to a side-face to side-face contact and can be between any surface of at least one projection (e.g. bump, extension, bulge, protrusion, other similar structure, or combinations thereof) on one fluid displacement member and any surface of at least one projection (e.g. bump, extension, bulge, protrusion, other similar structure, or combinations thereof) or indent (e.g., cavity, depression, void or other similar structure) on another fluid displacement member. Further, with respect to the drive-drive configurations, while two prime movers are used to independently and respectively drive two fluid displacement members in the above embodiments, it should be understood that those skilled in the art will recognize that some advantages (e.g., reduced contamination as compared to the driver-driven configuration) of the above-described embodiments can be achieved by using a single prime mover to independently drive two fluid displacement members. For example, in some embodiments, a single prime mover can independently drive the two fluid displacement members by the use of, e.g., timing gears, timing chains, or any device or combination of devices that independently drives two fluid displacement members while maintaining synchronization with respect to each other during operation.
The fluid displacement members, e.g., gears in the above embodiments, can be made entirely of any one of a metallic material or a non-metallic material. Metallic material can include, but is not limited to, steel, stainless steel, anodized aluminum, aluminum, titanium, magnesium, brass, and their respective alloys. Non-metallic material can include, but is not limited to, ceramic, plastic, composite, carbon fiber, and nano-composite material. Metallic material can be used for a pump that requires robustness to endure high pressure, for example. However, for a pump to be used in a low pressure application, non-metallic material can be used. In some embodiments, the fluid displacement members can be made of a resilient material, e.g., rubber, elastomeric material, to, for example, further enhance the sealing area.
Alternatively, the fluid displacement member, e.g., gears in the above embodiments, can be made of a combination of different materials. For example, the body can be made of aluminum and the portion that makes contact with another fluid displacement member, e.g., gear teeth in the above exemplary embodiments, can be made of steel for a pump that requires robustness to endure high pressure, a plastic for a pump for a low pressure application, a elastomeric material, or another appropriate material based on the type of application.
Exemplary embodiments of the fluid delivery system can displace a variety of fluids. For example, the pumps can be configured to pump hydraulic fluid, engine oil, crude oil, blood, liquid medicine (syrup), paints, inks, resins, adhesives, molten thermoplastics, bitumen, pitch, molasses, molten chocolate, water, acetone, benzene, methanol, or another fluid. As seen by the type of fluid that can be pumped, exemplary embodiments of the pump can be used in a variety of applications such as heavy and industrial machines, chemical industry, food industry, medical industry, commercial applications, residential applications, or another industry that uses pumps. Factors such as viscosity of the fluid, desired pressures and flow for the application, the configuration of the fluid displacement member, the size and power of the motors, physical space considerations, weight of the pump, or other factors that affect pump configuration will play a role in the pump arrangement. It is contemplated that, depending on the type of application, the exemplary embodiments of the fluid delivery system discussed above can have operating ranges that fall with a general range of, e.g., 1 to 5000 rpm. Of course, this range is not limiting and other ranges are possible.
The pump operating speed can be determined by taking into account factors such as viscosity of the fluid, the prime mover capacity (e.g., capacity of electric motor, hydraulic motor or other fluid-driven motor, internal-combustion, gas or other type of engine or other similar device that can drive a fluid displacement member), fluid displacement member dimensions (e.g., dimensions of the gear, hub with projections, hub with indents, or other similar structures that can displace fluid when driven), desired flow rate, desired operating pressure, and pump bearing load. In exemplary embodiments, for example, applications directed to typical industrial hydraulic system applications, the operating speed of the pump can be, e.g., in a range of 300 rpm to 900 rpm. In addition, the operating range can also be selected depending on the intended purpose of the pump. For example, in the above hydraulic pump example, a pump configured to operate within a range of 1-300 rpm can be selected as a stand-by pump that provides supplemental flow as needed in the hydraulic system. A pump configured to operate in a range of 300-600 rpm can be selected for continuous operation in the hydraulic system, while a pump configured to operate in a range of 600-900 rpm can be selected for peak flow operation. Of course, a single, general pump can be configured to provide all three types of operation.
In addition, the dimensions of the fluid displacement members can vary depending on the application of the pump. For example, when gears are used as the fluid displacement members, the circular pitch of the gears can range from less than 1 mm (e.g., a nano-composite material of nylon) to a few meters wide in industrial applications. The thickness of the gears will depend on the desired pressures and flows for the application.
In some embodiments, the speed of the prime mover, e.g., a motor, that rotates the fluid displacement members, e.g., a pair of gears, can be varied to control the flow from the pump. In addition, in some embodiments the torque of the prime mover, e.g., motor, can be varied to control the output pressure of the pump.
While the present invention has been disclosed with reference to certain embodiments, numerous modifications, alterations, and changes to the described embodiments are possible without departing from the sphere and scope of the present invention, as defined in the appended claims. Accordingly, it is intended that the present invention not be limited to the described embodiments, but that it has the full scope defined by the language of the following claims, and equivalents thereof.
The present application claims priority to International Patent Application No. PCT/US15/33776 filed Jun. 2, 2015 which claims priority to U.S. Provisional Patent Application Nos. 62/006,750 filed on Jun. 2, 2014; 62/007,719 and 62/007,723 filed on Jun. 4, 2014; 62/017,362, 62/017,395, and 62/017,413 filed on Jun. 26, 2014; 62/031,672, 62/031,353, and 62/031,597 filed on Jul. 31, 2014; 62/033,329 and 62/033,357 filed on Aug. 5, 2014; 62/054,176 filed on Sep. 23, 2014; 62/060,441 filed on Oct. 6, 2014; 62/066,261 filed on Oct. 20, 2014; and 62/072,132 filed on Oct. 29, 2014, which are incorporated herein by reference in their entirety.
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| Number | Date | Country | |
|---|---|---|---|
| 20170114807 A1 | Apr 2017 | US |
| Number | Date | Country | |
|---|---|---|---|
| 62072132 | Oct 2014 | US | |
| 62066261 | Oct 2014 | US | |
| 62060441 | Oct 2014 | US | |
| 62054176 | Sep 2014 | US | |
| 62033357 | Aug 2014 | US | |
| 62033329 | Aug 2014 | US | |
| 62031597 | Jul 2014 | US | |
| 62031353 | Jul 2014 | US | |
| 62131672 | Jul 2014 | US | |
| 62017413 | Jun 2014 | US | |
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| 62006750 | Jun 2014 | US |
