Patent Grant
11512695
The present invention relates generally to pumps and pumping methodologies thereof, and more particularly to pumps and methodologies thereof using two fluid drivers each integrated with an independently driven prime mover.
Pumps that transfer fluids can come in a variety of configurations. For example, one such type of pump is a gear pump. Gear pumps are positive displacement pumps (or fixed displacement), i.e. they pump a constant amount of fluid per each rotation and they are particularly suited for pumping high viscosity fluids such as crude oil. Gear pumps typically comprise a casing (or housing) having a cavity in which a pair of gears are arranged, one of which is known as a drive gear that is driven by a driveshaft attached to an external driver such as an engine or an electric motor, and the other of which is known as a driven gear (or idler gear) that meshes with the drive gear. Gear pumps in which both gears are externally toothed are referred to as external gear pumps. External gear pumps typically use spur, helical, or herringbone gears, depending on the intended application. Related art external gear pumps are equipped with one drive gear and one driven gear. When the drive gear attached to a rotor is rotatably driven by an engine or an electric motor, the drive gear meshes with and turns the driven gear. This rotary motion of the drive and driven gears carries fluid from the inlet of the pump to the outlet of the pump. In the above related art pumps, the fluid driver consists of the engine or electric motor and the pair of gears.
However, as gear teeth of the fluid drivers interlock with each other in order for the drive gear to turn the driven gear, the gear teeth grind against each other and contamination problems can arise in the system, whether it is in an open or closed fluid system, due to sheared materials from the grinding gears and/or contamination from other sources. The contamination in closed-loop systems is especially troublesome because the system fluid is recirculated without first going to a reservoir. These sheared materials are known to be detrimental to the functionality of the system, e.g., a hydraulic system, in which the gear pump operates. Sheared materials can be dispersed in the fluid, travel through the system, and damage crucial operative components, such as O-rings and bearings. It is believed that a majority of pumps fail due to contamination issues, e.g., in hydraulic systems. If the drive gear or the drive shaft fails due to a contamination issue, the whole system, e.g., the entire hydraulic system, could fail. Thus, known driver-driven gear pump configurations, which function to pump fluid as discussed above, have undesirable drawbacks due to the contamination problems.
In addition, the related-art systems are configured such that the prime mover (e.g., electric motor) is disposed outside the pump and a shaft extends through the pump casing to couple the motor to the drive gear. The opening in the casing for the shaft, while sealed to prevent fluid from leaking out, can still be a source of contamination. Also, related-art pumps have storage devices, e.g., accumulators, that are disposed separately from the pumps. These systems have interconnecting hoses and/or pipes between the pump and storage device, which introduce additional sources of contamination and increase the complexity of the system design.
Further, with respect to the internal pump configuration, the related-art gear pumps have bearing blocks that are configured to receive the shafts of the gears. The bearing blocks align the two gears such that the center axes of the gears are aligned with each other, such that the intermeshing of the gear teeth of the respective gears is to within an operational tolerance. However, because the bearing blocks in related-art pumps are separate components, seals and/or O-rings must be placed between each block and the corresponding pump casing, which adds to the complexity and weight of the pump assembly and also means more components that can fail.
Related-art systems do not solve the above-identified problems, especially in pumps used in industrial applications such as hydraulic systems. U.S. Patent Application Publication No. 2002/0009368 shows the use of independently driven motors to protect gear tooth surfaces from wear and excess stress in high-torque systems or systems with filler materials in the fluid. However, the motors in the '368 publication are external to the pump and thus would not eliminate all sources of contamination. In addition, the '368 publication does not teach to integrate the pump/prime mover and/or a storage device (e.g., an accumulator) to reduce or eliminate sources of contamination due to interconnections and an external motor configuration. Another related-art publication, WO 2011/035971, discloses a system in which a pump is integrated with a motor. However, the system in the '971 publication is a driver-driven system that can still introduce contamination due to the meshing of gears as discussed above. In addition, the '971 publication does not teach to integrate the pump and a storage device (e.g., an accumulator) to reduce or eliminate sources of contamination due to interconnections. Indeed, this concept is not even applicable because the fluid, i.e., fuel or mixture of urea and water, is consumed by the system and thus not recirculated. Therefore, any contamination has minimal impact, if any, as compared to, e.g., either a closed-loop or open-loop hydraulic system in which the fluid is recirculated. Further, the fuel pump and urea/water pump applications disclosed in the '971 publication are not comparable to the pressures and flows of a typical industrial hydraulics application such as, e.g., an actuator system that operates a boom of an excavator.
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.
Exemplary embodiments of the invention are directed to a pump having a casing in which two fluid drivers are disposed and a method of delivering fluid from an inlet of the pump to an outlet of the pump using the two fluid drivers. As used herein, “fluid” means a liquid or a mixture of liquid and gas containing mostly liquid with respect to volume. Each of the fluid drives includes a prime mover and a fluid displacement member. In some embodiments, the prime mover is partially or completely disposed inside the fluid displacement member. The prime mover drives the fluid displacement member and the prime mover can be, e.g., an electric motor or other similar device that can drive a fluid displacement member. The fluid displacement members transfer fluid when driven by the prime movers. The fluid displacement members are independently driven and thus have a drive-drive configuration. “Independently operate,” “independently operated,” “independently drive” and “independently driven” means each fluid displacement member is operated/driven by its own prime mover in a one-to-one configuration. For example, each gear in a pump is driven by its own electric motor. The drive-drive configuration eliminates or reduces the contamination problems of known driver-driven configurations.
The fluid displacement member can work in combination with a fixed element, e.g., pump wall or other similar component and/or a moving element such as, e.g., another fluid displacement member when transferring the fluid. The fluid displacement member can be, e.g., an 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. The fluid drivers are independently operated, e.g., with an electric motor or other similar device that can independently operate its fluid displacement member. However, the fluid drivers are operated such that contact between the fluid drivers is synchronized, e.g., in order to pump the fluid and/or seal a reverse flow path. That is, operation of the fluid drivers is synchronized such that the fluid displacement member in each fluid driver makes contact with another fluid displacement member. The contact can include at least one contact point, contact line, or contact area.
In some embodiments, synchronizing contact includes rotatably driving one of a pair of fluid drivers at a greater rate than the other so that a surface of one fluid driver contacts a surface of the other fluid driver. For example, the synchronized contact can be between a surface of at least one projection (bump, extension, bulge, protrusion, another similar structure or combinations thereof) on a first fluid displacement member of a first fluid driver and a surface of at least one projection (bump, extension, bulge, protrusion, another similar structure or combinations thereof) or an indent (cavity, depression, void or another similar structure) on a second fluid displacement member of a second fluid driver. In some embodiments, the synchronized contact seals a reverse flow path (or backflow path).
In an exemplary embodiment, a pump includes a casing defining an interior volume. The pump casing includes two self-aligning balancing plates that can be opposing walls of the pump casing. Each balancing plate includes a protruding portion extending toward the interior volume. Each protruded portion includes two recesses with each recess configured to accept one end of a fluid driver. The recesses can include bearings such as, e.g., sleeve-type bearing between the fluid driver and the wall of the respective recess. The recess portions of a balancing plate are aligned with and face the corresponding recess portions of the other balancing plate when the pump casing is assembled. The balancing plates align the fluid displacement members, i.e., the center axes of the fluid displacement members are aligned with respect to each other, such that the fluid displacement members contact and pump the fluid when rotated. For example, if the fluid displacement members are gears, the center axes of the gears will be aligned such that the respective gear teeth make proper contact with each other when rotated. In some embodiments, the balancing plates include cooling grooves connecting the respective recesses. The cooling grooves ensure that some of the liquid being transferred in the internal volume is directed to the bearings disposed in the recesses as the fluid drivers rotate. In some embodiments, only one self-aligning balancing plate is used and the opposing wall can be an end plate of the casing without the protruded portion.
In another exemplary embodiment, a pump includes a casing defining an interior volume. The pump casing includes two ports in fluid communication with the interior volume. One of the ports is an inlet to the pump and the other port is the outlet. In some embodiments, the pump is bi-directional so that the functions of inlet and outlet can be reversed. The pump includes two fluid drivers disposed within the interior volume. In some exemplary embodiments of the fluid driver, the fluid driver can include an electric motor with a stator and rotor. The stator can be fixedly attached to a support shaft and the rotor can surround the stator. The fluid driver can also include a gear having a plurality of gear teeth projecting radially outwardly from the rotor and supported by the rotor. In some embodiments, a support member can be disposed between the rotor and the gear to support the gear. The gears of the two fluid drivers are disposed such that a tooth of a first gear contacts a tooth of a second gear as the gears rotate. The first and second gears have first and second motor disposed within the respective gear's body. The first motor rotates the first gear in a first direction to transfer the fluid from the pump inlet to the pump outlet along a first flow path. The second motor rotates the second gear, independently of the first motor, in a second direction that is opposite the first direction to transfer the fluid from the pump inlet to the pump outlet along a second flow path. The pump includes a flow converging portion that is disposed between the inlet port and the first and second gears and a flow diverging portion between the first and second gears and the outlet port. The converging portion and the diverging portion reduce or eliminate the turbulence in the fluid as the fluid flows through the pump. The contact between the teeth of the first and second gears is coordinated by synchronizing the rotation of the first and second motors. The synchronized contact seals a reverse flow path (or a backflow path) between the outlet and inlet of the pump. In some embodiments the first motor and second motor are rotated at different revolutions per minute (rpm).
Another exemplary embodiment is directed to a method of delivering fluid from an inlet to an outlet of a pump having a casing to define an interior volume therein, and a first fluid driver with a first prime mover and a first fluid displacement member and a second fluid driver with a second prime mover and a second fluid displacement member. The first fluid displacement member can have a plurality of first projections and indents a second fluid displacement member having at least a plurality of second projections and indents. The pump casing includes two balancing plates that can be opposing walls of the pump casing. Each balancing plate includes a protruding portion extending toward the interior volume. Each protruded portion includes two recesses with each recess configured to accept one end of a fluid driver. In some embodiments, only one self-aligning balancing plate is used and the opposing wall can be an end plate of the casing without the protruded portion.
The method includes disposing each end of each fluid driver in a recess to axially align the fluid displacement members relative to one another. The method further includes rotating the first prime mover to rotate the first fluid displacement member in a first direction to transfer a fluid from the pump inlet to the pump outlet along a first flow path and to transfer a portion of the fluid in the interior volume to a recess. The method includes rotating the second prime mover, independently of the first prime mover, to rotate the second fluid displacement member in a second direction that is opposite the first direction to transfer the fluid from the pump inlet to the pump outlet along a second flow path and to transfer a portion of the fluid in the interior volume to a recess. The method also includes synchronizing a speed of the second fluid displacement member to be in a range of 99 percent to 100 percent of a speed of the first fluid displacement member and synchronizing contact between the first displacement member and the second displacement member such that a surface of at least one of the plurality of first projections (or at least one first projection) contacts a surface of at least one of the plurality of second projections (or at least one second projection) or a surface of at least one of the plurality of indents (or at least one second indent). In some embodiments, the synchronized contact seals a reverse flow path between the inlet and outlet of the pump.
Another exemplary embodiment is directed to a method of transferring fluid from a first port to a second port of a pump that includes a pump casing, which defines an interior volume. The pump casing includes two self-aligning balancing plates that can be opposing walls of the pump casing. Each balancing plate includes a protruding portion extending toward the interior volume. Each protruded portion includes two recesses with each recess configured to accept one end of a fluid driver. In some embodiments, only one self-aligning balancing plate is used and the opposing wall can be an end plate of the casing without the protruded portion. The pump further includes a first fluid driver having a first motor and a first gear having a plurality of first gear teeth, and a second fluid driver having a second motor and a second gear having a plurality of second gear teeth.
The method includes disposing each end of each fluid driver in a recess to axially align the plurality of first and second gear teeth such that they make synchronous contact when the gears are rotated. The method includes rotating the first motor to rotate the first gear about a first axial centerline of the first gear in a first direction. The rotation of the first gear transfers the fluid from the pump inlet to the pump outlet along a first flow path. The method also includes rotating the second motor, independently of the first motor, to rotate the second gear about a second axial centerline of the second gear in a second direction that is opposite the first direction. The rotation of the second gear transfers the fluid from the pump inlet to the pump outlet along a second flow path. In some embodiments, the method further includes synchronizing contact between a surface of at least one tooth of the plurality of second gear teeth and a surface of at least one tooth of the plurality of first gear teeth. In some embodiments, the synchronizing the contact includes rotating the first and second motors at different rpms. In some embodiments, the synchronized contact seals a reverse flow path between the inlet and outlet of the pump.
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 configuration. 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 preferred embodiments of the invention.
Exemplary embodiments of the present invention are directed to a pump with independently driven fluid drivers disposed between two self-aligning balancing plates that form part of the pump casing. These exemplary embodiments will be described using embodiments in which the pump is an external gear pump with two prime movers, the prime movers are electric motors and the fluid displacement members are external spur gears with gear teeth. However, those skilled in the art will readily recognize that the concepts, functions, and features described below with respect to electric-motor-driven external gear pump with two fluid drivers can be readily adapted to external gear pumps with other gear designs (helical gears, herringbone gears, or other gear teeth designs that can be adapted to drive fluid), to prime movers other than electric motors, e.g., hydraulic motors or other fluid-driven motors, or other similar devices that can drive a fluid displacement member, and to fluid displacement members other than a gear with gear teeth, e.g., 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 addition, the exemplary embodiments may be described with respect to a hydraulic fluid as the fluid being pumped. However, exemplary embodiments of the present disclosure are not limited to hydraulic fluid and can be used for fluids such as, e.g., water.
The casing 20 has ports 22 and 24 (see
As discussed earlier, to ensure proper alignment of the gears, conventional external gear pumps typically include separately provided bearing blocks. However, in some exemplary embodiments, the external gear pump 10 of the present disclosure does not include separately provided bearing blocks. Instead, each of the end plates 80, 82 includes protruded portions 45 disposed on the interior portion (i.e., internal volume 11 side) of the end plates 80, 82, thereby eliminating the need for separately provided bearing blocks. That is, one feature of the protruded portions 45 is to ensure that the gears are properly aligned, a function performed by bearing blocks in conventional external gear pumps. However, unlike traditional bearing blocks, the protruded portions 45 of each end plate 80, 82 provide additional mass and structure to the casing 20 so that the pump 10 can withstand the pressure of the fluid being pumped. In conventional pumps, the mass of the bearing blocks is in addition to the mass of the casing, which is designed to hold the pump pressure. Thus, because the protruded portions 45 of the present disclosure serve to both align the gears and provide the mass required by the pump casing 20, the overall mass of the structure of pump 10 can be reduced in comparison to conventional pumps of a similar capacity.
As seen in
As seen in
As seen in
In some embodiments, only one of the plates 80, 82 has protruded portion 45. For example, end plate 80 can include a protruded portion 45 and the end plate 82 can be a cover plate with appropriate features such as, e.g., openings to accept the shafts of the fluid drivers 40, 60. In such embodiments, the gears 50, 70 can be disposed on an end of the fluid drivers 40, 60 (not shown) instead of in the center of the fluid drivers 40, 60 as shown in
Preferably, as seen in
In some embodiments, one or more cooling grooves may be provided in each protruded portion 45 to transfer a portion of the fluid in the internal volume 11 to the recesses 53 to lubricate bearings 57. For example, as shown in
Turning to the exemplary embodiment shown in
As best seen in
During operation, as the fluid enters the inlet of the pump 10, e.g., port 22 for exemplary purposes, the fluid encounters the converging flow passage 39 where the cross-sectional area of at least a portion of the passage 39 is gradually reduced as the fluid flows to the gears 50, 70. The converging flow passage 39 minimizes abrupt changes in speed and pressure of the fluid and facilitates a gradual transition of the fluid into the gears 50, 70 of pump 10. The gradual transition of the fluid into the pump 10 can reduce bubble formation or turbulent flow that may occur in or outside the pump 10, and thus can prevent or minimize cavitation. Similarly, as the fluid exits the gears 50. 70, the fluid encounters a diverging flow passage 43 in which the cross-sectional areas of at least a portion of the passage is gradually expanded as the fluid flows to the outlet port, e.g., port 24. Thus, the diverging flow passage 43 facilitates a gradual transition of the fluid from the outlet of gears 50, 70 to stabilize the fluid.
An exemplary embodiment of the fluid drivers 40, 60 is given with reference to
Turning to the motors 41, 61 of the fluid drivers 40, 60, the stators 44, 64 are disposed radially between the respective support shafts 42, 62 and the rotors 46, 66. The stators 44, 64 are fixedly connected to the respective support shafts 42, 62, which are fixedly connected to the casing 20. The rotors 46, 66 are disposed radially outward of the stators 44, 64 and surround the respective stators 44, 64. Thus, the motors 41, 61 in this embodiment are of an outer-rotor motor design (or an external-rotor motor design), which means that that the outside of the motor rotates and the center of the motor is stationary. In contrast, in an internal-rotor motor design, the rotor is attached to a central shaft that rotates. In an exemplary embodiment, the motors 41, 61 are multi directional electric motors. That is, either motor can operate to create rotary motion that is either clockwise or counter-clockwise depending on operational needs. Further, in an exemplary embodiment, the motors 41, 61 are variable-speed, variable-torque motors in which the speed and/or torque of the rotor and thus the attached gear can be varied to create various volume flows and pump pressures.
Each fluid driver 40, 60 includes a motor casing that houses the respective shafts 42, 62, stators 44, 64 and rotors 46, 66 of the motors 41, 61. In some embodiments, the casings of the motors 41, 61 and the respective gears 50, 70 form a single unit. For example,
As seen in
As seen in
In a preferred embodiment, the gear teeth 52, 72 are formed on and are part of the respective motor casing body 89. That is, the gear bodies of gears 50, 70 and the motor casing of motors 41, 61 are the same. Thus, the motor casing bodies 89 and their respective gear teeth 52, 72 are provided as one piece. For example, the outer surfaces of motor casing body 89 can be machined to form the gear teeth 52, 72 in the center of the casing body 89 as shown in
However, in other exemplary embodiments, the gears 50, 70 can be manufactured separately from the motor casing body 89 and then joined. For example, a ring-shaped gear assembly that includes the gear teeth can be manufactured and joined to the motor casing via a welding process, for example. Of course, other methods can be used to join the two components, e.g., a press fit, an interference fit, bonding, or some other means of attachment. As such, the manufacturing method of the motor casing/gear can vary without departing from the spirit of the present disclosure. In addition, in some embodiments, the motor casing assembly 87 is configured to accept motors that can include their own casings. That is, the motor casing assembly 87 can act as an additional protective cover over the motor's original casing. This allows the motor casing body 89 to accept a variety of “off-the-shelf” motors for greater flexibility in terms of pump capacity and reparability. In addition, there will be greater flexibility in terms of providing the proper material composition for the motor casing assembly 87 with respect to, e.g., the fluid being pumped if the motor has its own casing. For example, the motor casing assembly 87 can be made of a material to withstand a corrosive fluid while the motor is protected by a casing made of a different material. In some embodiments that have only one protruded portion 45, the motor casing body 89 may not include the gears 50, 70 and the gears 50, 70 can be mounted at the end of the motors 41, 61. In such embodiments, the recesses 53 of the protruded portion 45 can be sized to accept the motor casing bodies 89 such that the gears 50, 70 and land 55 are properly aligned between the land 55 and the cover plate.
Detailed description of the 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 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 related art systems, the contact force is not so large as to significantly drive the other gear. In related art driver-driven systems, the force applied by the driver gear turns the driven gear, i.e., 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. This large force causes material to shear off from the teeth in related art pumps. These sheared materials can be dispersed in the fluid, travel through the hydraulic system, and damage crucial operative components, such as O-rings and bearings. As a result, a whole pump system can fail and could interrupt operation of the pump. This failure and interruption of the operation of the pump can lead to significant downtime to repair the pump.
In exemplary embodiments of the pump 10, 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 the driver-driven configurations discussed above, 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 positons remain synchronized with respect to each other during operation. Thus, the above-described issues caused by sheared materials in conventional gear pumps are effectively avoided.
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 positons 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 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. 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 designed so as to not trap excessive fluid pressure between the teeth in the contact area 78. As illustrated in
In the above discussed exemplary embodiments, both fluid drivers 40, 60, including electric motors 41, 61 and gears 50, 70, are integrated into a single pump casing 20. This novel configuration of the external gear pump 10 of the present disclosure enables a compact design that provides various advantages. First, the space or footprint occupied by the gear pump embodiments discussed above is significantly reduced by integrating necessary components into a single pump casing, when compared to conventional gear pumps. In addition, the total weight of a pump system is also reduced by removing unnecessary parts such as a shaft that connects a motor to a pump, and separate mountings for a motor/gear driver. Further, since the pump 10 of the present disclosure has a compact and modular design, it can be easily installed, even at locations where conventional gear pumps could not be installed, and can be easily replaced.
In addition, the novel balancing plate configuration provides various additional advantages. First, design of a gear pump is simplified. The need for a separately provided bearing block is eliminated by incorporating protruded portion 45 with recesses 53 into the pump design. Seal(s) and/or O-ring(s) disposed between each bearing block and the corresponding cover can be eliminated as well. As a lower number of seals and/or O-rings is employed in a gear pump, the probability of leakage in case of failure of these seals and/or O-rings is reduced. Further, the stiffness of each end plate 80, 82 is increased because the protruded portions 45 are part of or integrally attached to the respective balancing plate 80, 82, thus the pump 10 is less vulnerable to loads, e.g. bending loads, imposed during a pumping operation and structural stability (or structural durability) of the pump 10 is improved.
In some exemplary embodiments of the present disclosure, the pump includes a fluid storage device that is fixedly attached to the pump so as to form one integrated unit. For example,
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, the flow-through shaft 62′ also penetrates through an opening in the end plate 80 and into the fluid chamber 172 of the storage device 170. The flow-through shaft 62′ includes a through-passage 194 that extends through the interior of shaft 62′. The through-passage 194 has a port 196 at an end of flow-through shaft 62 that leads to the fluid chamber 172 such that the through-passage 194 is in fluid communication with the fluid chamber 172. At the other end of flow-through shaft 62, the through-passage 194 connects to a fluid channel 192 that extends through the end plate 82 and connects to either port 22 or 24 (not shown) such that the through-passage 194 is in fluid communication with a port of the pump 10′. In this way, the fluid chamber 172 is in fluid communication with a port of the pump 10′.
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 presses against 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) into a port of the pump 10′ (or ports—depending on the arrangement) until the pressure in the storage device 170 is in equilibrium with the pressure at the port (ports) of the pump 10′. During operation, if the pressure at the relevant port drops below the pressure in the fluid chamber 172, the pressurized fluid from the storage device 170 is pushed to the appropriate port until the pressures equalize. Conversely, if the pressure at the relevant port goes higher than the pressure of fluid chamber 172, the fluid from the port is pushed to the fluid chamber 172 via through-passages 184 and 194.
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 182 for through-passage 184—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 balancing 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 balancing plates 80, 82 without penetrating into the fluid chamber 172.
In the above embodiments, the storage device 170 is mounted on the balancing plate 80 of the casing 20. However, in other embodiments, the storage device 170 can be mounted on the balancing 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.
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,
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 194 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
Although the above embodiments were described with respect to an external gear pump design 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 designs (helical gears, herringbone gears, or other gear teeth designs that can be adapted to drive fluid), to pumps having more than two prime movers, to prime movers other than electric motors, e.g., hydraulic motors or other fluid-driven motors 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 designs are omitted. Further, while the above embodiments have fluid displacement members with an external gear design, those skilled in the art will recognize that, depending on the type of fluid displacement member, the synchronized contact 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.
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, etc., 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 pumps of the present disclosure can pump a variety of fluids. For example, the pumps can be designed 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 design 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 design will play a role in the pump design. It is contemplated that, depending on the type of application, pumps consistent with the embodiments 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 designed 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 designed to operate in a range of 300-600 rpm can be selected for continuous operation in the hydraulic system, while a pump designed to operate in a range of 600-900 rpm can be selected for peak flow operation. Of course, a single, general pump can be designed to provide all three types of operation.
The applications of the exemplary embodiments can include, but are not limited to, reach stackers, wheel loaders, forklifts, mining, aerial work platforms, waste handling, agriculture, truck crane, construction, forestry, and machine shop industry. For applications that are categorized as light size industries, exemplary embodiments of the pump discussed above can displace from 2 cm3/rev (cubic centimeters per revolution) to 150 cm3/rev with pressures in a range of 1500 psi to 3000 psi, for example. The fluid gap, i.e., tolerance between the gear teeth and the gear housing which defines the efficiency and slip coefficient, in these pumps can be in a range of +0.00-0.05 mm, for example. For applications that are categorized as medium size industries, exemplary embodiments of the pump discussed above can displace from 150 cm3/rev to 300 cm3/rev with pressures in a range of 3000 psi to 5000 psi and a fluid gap in a range of +0.00-0.07 mm, for example. For applications that are categorized as heavy size industries, exemplary embodiments of the pump discussed above can displace from 300 cm3/rev to 600 cm3/rev with pressures in a range of 3000 psi to 12,000 psi and a fluid gap in a range of +0.00-0.0125 mm, for example.
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.
This application is a continuation of U.S. application Ser. No. 16/787,876 filed Feb. 11, 2020, which is a continuation of U.S. application Ser. No. 15/327,748 filed Jan. 20, 2017 (now U.S. Pat. No. 10,598,176), which is a 371 filing of International Application No. PCT/US2015/041612, which was filed Jul. 22, 2015, and which claims priority to U.S. Provisional Patent Application Nos. 62/027,330 filed Jul. 22, 2014; 62/060,431 filed Oct. 6, 2014; and 62/066,198 filed Oct. 20, 2014, each of which applications is incorporated herein by reference in its entirety.
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| U.S. Appl. No. 17/364,305, filed Jun. 30, 2021, now abandoned, titled Hydrostatic Transmission Assembly and System. |
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| Number | Date | Country | |
|---|---|---|---|
| 20210317828 A1 | Oct 2021 | US |
| Number | Date | Country | |
|---|---|---|---|
| 62066198 | Oct 2014 | US | |
| 62060431 | Oct 2014 | US | |
| 62027330 | Jul 2014 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 16787876 | Feb 2020 | US |
| Child | 17243483 | US | |
| Parent | 15327748 | US | |
| Child | 16787876 | US |
