Patent Grant
9810242
Various off-road and on-road vehicles include booms. For example, certain concrete pump trucks include a boom configured to support a passage through which concrete is pumped from a base of the concrete pump truck to a location at a construction site where the concrete is needed. Such booms may be long and slender to facilitate pumping the concrete a substantial distance away from the concrete pump truck. In addition, such booms may be relatively heavy. The combination of the substantial length and mass properties of the boom may lead to the boom exhibiting undesirable dynamic behavior. In certain booms in certain configurations, a natural frequency of the boom may be about 0.3 Hertz (i.e., 3.3 seconds per cycle). In certain booms in certain configurations, the natural frequency of the boom may be less than about 1 Hertz (i.e., 1 second per cycle). In certain booms in certain configurations, the natural frequency of the boom may range from about 0.1 Hertz to about 1 Hertz (i.e., 10 seconds per cycle to 1 second per cycle). For example, as the boom is moved from place to place, the starting and stopping loads that actuate the boom may induce vibration (i.e., oscillation). Other load sources that may excite the boom include momentum of the concrete as it is pumped along the boom, starting and stopping the pumping of concrete along the boom, wind loads that may develop against the boom, and/or other miscellaneous loads.
Other vehicles with booms include fire trucks in which a ladder may be included on the boom, fire trucks which include a boom with plumbing to deliver water to a desired location, excavators which use a boom to move a shovel, tele-handlers which use a boom to deliver materials around a construction site, cranes which may use a boom to move material from place to place, etc.
In certain boom applications, including those mentioned above, a hydraulic cylinder may be used to actuate the boom. By actuating the hydraulic cylinder, the boom may be deployed and retracted, as desired, to achieve a desired placement of the boom. In certain applications, counter-balance valves may be used to control actuation of the hydraulic cylinder and/or to prevent the hydraulic cylinder from uncommanded movement (e.g., caused by a component failure). A prior art system 100, including a first counter-balance valve 300 and a second counter-balance valve 400 is illustrated at
The counter-balance valves 300, 400 provide safety protection to the system 100. In particular, before movement of the cylinder 110 can occur, hydraulic pressure must be applied to both of the counter-balance valves 300, 400. The hydraulic pressure applied to one of the counter-balance valves 300, 400 is delivered to a corresponding one of the ports 122, 124 of the hydraulic cylinder 110 thereby urging a piston 120 of the hydraulic cylinder 110 to move. The hydraulic pressure applied to an opposite one of the counter-balance valves 400, 300 allows hydraulic fluid to flow out of the opposite port 124, 122 of the hydraulic cylinder 110. By requiring hydraulic pressure at the counter-balance valve 300, 400 corresponding to the port 122, 124 that is releasing the hydraulic fluid, a failure of a hydraulic line, a valve, a pump, etc. that supplies or receives the hydraulic fluid from the hydraulic cylinder 110 will not result in uncommanded movement of the hydraulic cylinder 110.
Turning now to
When the spool 220 is positioned at the second configuration 224, hydraulic fluid flow between the port 202 and the port 212 and hydraulic fluid flow between the port 204 and the port 214 is effectively stopped, and hydraulic fluid flow to and from the cylinder 110 is effectively stopped. Thus, the hydraulic cylinder 110 remains substantially stationary when the spool 220 is positioned at the second configuration 224.
When the spool 220 is positioned at the third configuration 226, hydraulic fluid flow from the supply line 502 enters through the port 212 and exits through the port 204 of the valve 200. The hydraulic fluid flow is ultimately delivered to the port 124 and the chamber 118 of the hydraulic cylinder 110 thereby urging retraction of the cylinder 110. As hydraulic fluid pressure is applied to the chamber 118, hydraulic fluid within the chamber 116 is urged to exit through the port 122. Hydraulic fluid exiting the port 122 enters the port 202 and exits the port 214 of the valve 200 and thereby returns to the hydraulic tank. An operator and/or a control system may move the spool 220 as desired and thereby achieve extension, retraction, and/or locking of the hydraulic cylinder 110.
A function of the counter-balance valves 300, 400 when the hydraulic cylinder 110 is extending will now be discussed in detail. Upon the spool 220 of the valve 200 being placed in the first configuration 222, hydraulic fluid pressure from the supply line 502 pressurizes a hydraulic line 512. The hydraulic line 512 is connected between the port 202 of the control valve 200, a port 304 of the counter-balance valve 300, and a port 406 of the counter-balance valve 400. Hydraulic fluid pressure applied at the port 304 of the counter-balance valve 300 flows past a spool 310 of the counter-balance valve 300 and past a check valve 320 of the counter-balance valve 300 and thereby flows from the port 304 to the port 302 through a passage 322 of the counter-balance valve 300. The hydraulic fluid pressure further flows through the port 122 and into the chamber 116 (i.e., a meter-in chamber). Pressure applied to the port 406 of the counter-balance valve 400 moves a spool 410 of the counter-balance valve 400 against a spring 412 and thereby compresses the spring 412. Hydraulic fluid pressure applied at the port 406 thereby opens a passage 424 between the port 402 and the port 404. By applying hydraulic pressure at the port 406, hydraulic fluid may exit the chamber 118 (i.e., a meter-out chamber) through the port 124, through the line 524, through the passage 424 of the counter-balance valve 400 across the spool 410, through a hydraulic line 514, through the valve 200, and through the return line 504 into the tank. The meter-out side may supply backpressure.
A function of the counter-balance valves 300, 400 when the hydraulic cylinder 110 is retracting will now be discussed in detail. Upon the spool 220 of the valve 200 being placed in the third configuration 226, hydraulic fluid pressure from the supply line 502 pressurizes the hydraulic line 514. The hydraulic line 514 is connected between the port 204 of the control valve 200, a port 404 of the counter-balance valve 400, and a port 306 of the counter-balance valve 300. Hydraulic fluid pressure applied at the port 404 of the counter-balance valve 400 flows past the spool 410 of the counter-balance valve 400 and past a check valve 420 of the counter-balance valve 400 and thereby flows from the port 404 to the port 402 through a passage 422 of the counter-balance valve 400. The hydraulic fluid pressure further flows through the port 124 and into the chamber 118 (i.e., a meter-in chamber). Hydraulic pressure applied to the port 306 of the counter-balance valve 300 moves the spool 310 of the counter-balance valve 300 against a spring 312 and thereby compresses the spring 312. Hydraulic fluid pressure applied at the port 306 thereby opens a passage 324 between the port 302 and the port 304. By applying hydraulic pressure at the port 306, hydraulic fluid may exit the chamber 116 (i.e., a meter-out chamber) through the port 122, through the line 522, through the passage 324 of the counter-balance valve 300 across the spool 310, through the hydraulic line 512, through the valve 200, and through the return line 504 into the tank. The meter-out side may supply backpressure.
The supply line 502, the return line 504, the hydraulic line 512, the hydraulic line 514, the hydraulic line 522, and/or the hydraulic line 524 may belong to a line set 500.
One aspect of the present disclosure relates to systems and methods for reducing boom dynamics (e.g., boom bounce) of a boom while providing counter-balance valve protection to the boom.
Another aspect of the present disclosure relates to a hydraulic system including a hydraulic cylinder, a first counter-balance valve, a second counter-balance valve, a first control valve, a second control valve, and a selection valve arrangement. The hydraulic cylinder includes a first chamber and a second chamber. The first counter-balance valve fluidly connects to the first chamber at a first node, and the second counter-balance valve fluidly connects to the second chamber at a second node. The first control valve fluidly connects to the first counter-balance valve at a third node, and a second control valve fluidly connects to the second counter-balance valve at a fourth node. The selection valve arrangement is fluidly connected to the first node and the second node and is adapted to self-configure to a first configuration set when a net load is supported by the second chamber of the hydraulic cylinder and is further adapted to self-configure to a second configuration set when the net load is supported by the first chamber of the hydraulic cylinder. When the selection valve arrangement is enabled and at the first configuration set, the first control valve is adapted to fluctuate a first hydraulic fluid flow to the first chamber and thereby cause the hydraulic cylinder to produce a first vibratory response.
In certain embodiments, when the selection valve arrangement is enabled and at the second configuration set, the second control valve is adapted to fluctuate a second hydraulic fluid flow to the second chamber and thereby cause the hydraulic cylinder to produce a second vibratory response. In certain embodiments, the first chamber is a rod chamber and the second chamber is a head chamber. In other embodiments, the first chamber is a head chamber and the second chamber is a rod chamber. In certain embodiments, the first counter-balance valve, the second counter-balance valve, and the selection valve arrangement are physically mounted to the hydraulic cylinder.
Still another aspect of the present disclosure relates to a hydraulic valve set including a first counter-balance valve, a second counter-balance valve, and a selection valve arrangement. The first counter-balance valve provides a first back-flow protection to a first node. The first counter-balance valve includes a first counter-balance valve opening node. The second counter-balance valve provides a second back-flow protection to a second node. The second counter-balance valve includes a second counter-balance valve opening node. The selection valve arrangement is fluidly connected to the first node, the second node, the first counter-balance valve opening node, and the second counter-balance valve opening node. The selection valve arrangement is adapted to self-configure in response to a net spool force produced by a first fluid pressure of the first node and a second fluid pressure of the second node. When the net spool force is in a first direction, the selection valve arrangement connects the first node of the first counter-balance valve to the second counter-balance valve opening node of the second counter-balance valve. When the net spool force is in a second direction, the selection valve arrangement connects the second node of the second counter-balance valve to the first counter-balance valve opening node of the first counter-balance valve.
Yet another aspect of the present disclosure relates to a hydraulic boom control system including a pair of counter-balance valves, a selection valve arrangement, and a pair of control valves. The pair of counter-balance valves is hydraulically coupled to opposite sides of a hydraulic actuator of a boom. The selection valve arrangement senses a net unloaded side of the opposite sides of the hydraulic actuator and opens a one of the pair of counter-balance valves corresponding to the net unloaded side. The pair of control valves corresponds to the opposite sides of the hydraulic actuator. A one of the pair of control valves corresponds to the net unloaded side and transmits a vibratory hydraulic fluid flow to the net unloaded side of the hydraulic actuator.
Still another aspect of the present disclosure relates to a method of controlling vibration in a boom. The method includes: 1) providing a valve arrangement that includes a pair of counter-balance valves, a pair of control valves, and a selector valve set; 2) providing a hydraulic actuator that includes a pair of chambers; 3) configuring the selector valve set with a net load that is applied on the hydraulic actuator and thereby configures the pair of counter-balance valves; 4) locking a loaded chamber of the pair of chambers with a respective one of the pair of counter-balance valves that has been configured by the configuring of the pair of counter-balance valves; and 5) transmitting vibrating hydraulic fluid with a respective one of the pair of control valves to an unloaded chamber of the pair of chambers.
A variety of additional aspects will be set forth in the description that follows. These aspects can relate to individual features and to combinations of features. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the broad concepts upon which the embodiments disclosed herein are based.
According to the principles of the present disclosure, a hydraulic system is adapted to actuate the hydraulic cylinder 110, including the counter-balance valves 300 and 400, and further provide means for counteracting vibrations to which the hydraulic cylinder 110 is exposed. As illustrated at
According to the principles of the present disclosure, similar protection is provided by the counter-balance valves 300, 400 for the hydraulic cylinder 110 and the hydraulic system 600, as described above with respect to the hydraulic system 100. In particular, failure of a hydraulic line, a hydraulic valve, and/or a hydraulic pump will not lead to an uncommanded movement of the hydraulic cylinder 110 of the hydraulic system 600. The hydraulic architecture of the hydraulic system 600 further provides the ability to counteract vibrations using the hydraulic cylinder 110.
The hydraulic cylinder 110 may hold a net load 90 that, in general, may urge retraction or extension of a rod 126 of the cylinder 110. The rod 126 is connected to the piston 120 of the cylinder 110. If the load 90 urges extension of the hydraulic cylinder 110, the chamber 118 on a rod side 114 of the hydraulic cylinder 110 is pressurized by the load 90, and the counter-balance valve 400 acts to prevent the release of hydraulic fluid from the chamber 118 and thereby acts as a safety device to prevent uncommanded extension of the hydraulic cylinder 110. In other words, the counter-balance valve 400 locks the chamber 118. In addition to providing safety, the locking of the chamber 118 prevents drifting of the cylinder 110. Vibration control may be provided via the hydraulic cylinder 110 by dynamically pressurizing and depressurizing the chamber 116 on a head side 112 of the hydraulic cylinder 110. As the hydraulic cylinder 110, the structure to which the hydraulic cylinder 110 is attached, and the hydraulic fluid within the chamber 118 are at least slightly deformable, selective application of hydraulic pressure to the chamber 116 will cause movement (e.g., slight movement) of the hydraulic cylinder 110. Such movement, when timed in conjunction with a system model and dynamic measurements of the system, may be used to counteract vibrations of the system.
If the load 90 urges retraction of the hydraulic cylinder 110, the chamber 116 on the head side 112 of the hydraulic cylinder 110 is pressurized by the load 90, and the counter-balance valve 300 acts to prevent the release of hydraulic fluid from the chamber 116 and thereby acts as a safety device to prevent uncommanded retraction of the hydraulic cylinder 110. In other words, the counter-balance valve 300 locks the chamber 116. In addition to providing safety, the locking of the chamber 116 prevents drifting of the cylinder 110. Vibration control may be provided via the hydraulic cylinder 110 by dynamically pressurizing and depressurizing the chamber 118 on the rod side 114 of the hydraulic cylinder 110. As the hydraulic cylinder 110, the structure to which the hydraulic cylinder 110 is attached, and the hydraulic fluid within the chamber 116 are at least slightly deformable, selective application of hydraulic pressure to the chamber 118 will cause movement (e.g., slight movement) of the hydraulic cylinder 110. Such movement, when timed in conjunction with the system model and dynamic measurements of the system, may be used to counteract vibrations of the system.
The load 90 is depicted as attached via a rod connection 128 to the rod 126 of the cylinder 110. In certain embodiments, the load 90 is a tensile or a compressive load across the rod connection 128 and the head side 112 of the cylinder 110.
As is further described below, the system 600 provides a control framework and a control mechanism to achieve boom vibration reduction for both off-highway vehicles and on-highway vehicles. The vibration reduction may be adapted to reduced vibrations in booms with relatively low natural frequencies (e.g., the concrete pump truck boom). The hydraulic system 600 may also be applied to booms with relatively high natural frequencies (e.g., an excavator boom). Compared with conventional solutions, the hydraulic system 600 achieves vibration reduction of booms with fewer sensors and a simplified control structure. The vibration reduction method may be implemented while assuring protection from failures of certain hydraulic lines, hydraulic valves, and/or hydraulic pumps, as described above. The protection from failure may be automatic and/or mechanical. In certain embodiments, the protection from failure may not require any electrical signal and/or electrical power to engage. The protection from failure may be a regulatory requirement (e.g., an ISO standard). The regulatory requirement may require certain mechanical means of protection that is provided by the hydraulic system 600.
Certain booms may include stiffness and inertial properties that can transmit and/or amplify dynamic behavior of the load 90. As the dynamic load 90 may include external force/position disturbances that are applied to the boom, severe vibrations (i.e., oscillations) may result especially when these disturbances are near the natural frequency of the boom. Such excitation of the boom by the load 90 may result in safety issues and/or decrease productivity and/or reliability of the boom system. By measuring parameters of the hydraulic system 600 and responding appropriately, effects of the disturbances may be reduced and/or minimized or even eliminated. The response provided may be effective over a wide variety of operating conditions. According to the principles of the present disclosure, vibration control may be achieved using minimal numbers of sensors.
According to the principles of the present disclosure, hydraulic fluid flow to the chamber 116 of the head 112 side of the cylinder 110, and hydraulic fluid flow to the chamber 118 of the rod side 114 of the cylinder 110 are independently controlled and/or metered to realize boom vibration reduction and also to prevent the cylinder 110 from drifting. According to the principles of the present disclosure, the hydraulic system 600 may be configured similar to a conventional counter-balance system (e.g., the hydraulic system 100).
In certain embodiments, the hydraulic system 600 is configured to the conventional counter-balance configuration when a movement of the cylinder 110 is commanded. As further described below, the hydraulic system 600 enables measurement of pressures within the chambers 116 and/or 118 of the cylinder 110 at a remote location away from the hydraulic cylinder 110 (e.g., at sensors 610). This architecture thereby may reduce mass that would otherwise be positioned on the boom and/or may simplify routing of hydraulic lines (e.g., hard tubing and hoses). Performance of machines such as concrete pump booms and/or lift handlers may be improved by such simplified hydraulic line routing and/or reduced mass on the boom.
The counter-balance valves 300 and 400 may be components of a valve arrangement 840. The valve arrangement 840 may include various hydraulic components that control and/or regulate hydraulic fluid flow to and/or from the hydraulic cylinder 110. The valve arrangement 840 may further include a control valve 700 (e.g., a proportional hydraulic valve), a control valve 800 (e.g., a proportional hydraulic valve), and a selector valve arrangement 850, described in detail below. The control valves 700 and/or 800 may be high bandwidth and/or high resolution control valves.
In the depicted embodiment of
Turning now to
Turning now to
As depicted at
As depicted, the boom 30 includes a plurality of boom segments 36. Adjacent pairs of the boom segments 36 may be connected to each other by a corresponding joint 38. As depicted, a first boom segment 361 is rotatably attached to the vehicle 20 at a first joint 381. The first boom segment 361 may be mounted by two rotatable joints. For example, the first rotatable joint may include a turntable, and the second rotatable joint may include a horizontal axis. A second boom segment 362 is attached to the first boom segment 361 at a second joint 382. Likewise, a third boom segment 363 is attached to the second boom segment 362 at a joint 383, and a fourth boom segment 364 is attached to the third boom segment 363 at a fourth joint 384. A relative position/orientation between the adjacent pairs of the boom segments 36 may be controlled by a corresponding hydraulic cylinder 110. For example, a relative position/orientation between the first boom segment 361 and the vehicle 20 is controlled by a first hydraulic cylinder 1101. The relative position/orientation between the first boom segment 361 and the second boom segment 362 is controlled by a second hydraulic cylinder 1102. Likewise, the relative position/orientation between the third boom segment 363 and the second boom segment 362 may be controlled by a third hydraulic cylinder 1103, and the relative position/orientation between the fourth boom segment 364 and the third boom segment 363 may be controlled by a fourth hydraulic cylinder 1104.
According to the principles of the present disclosure, the boom 30, including the plurality of boom segments 361-4, may be modeled and vibration of the boom 30 may be controlled by a controller 640. In particular, the controller 640 may send a signal 652 to the valve 700 and a signal 654 to the valve 800. The signal 652 may include a vibration component 652v, and the signal 654 may include a vibration component 654v. The vibration component 652v, 654v may cause the respective valve 700, 800 to produce a vibratory flow and/or a vibratory pressure at the respective port 702, 804. The vibratory flow and/or the vibratory pressure may be transferred through the respective counter-balance valve 300, 400 and to the respective chamber 116, 118 of the hydraulic cylinder 110.
The signals 652, 654 of the controller 640 may also include move signals that cause the hydraulic cylinder 110 to extend and retract, respectively, and thereby actuate the boom 30. As depicted at
The controller 640 may receive input from various sensors, including the sensors 610, position sensors, LVDTs, vision base sensors, etc. and thereby compute the signals 652, 654, including the vibration component 652v, 654v. The controller 640 may include a dynamic model of the boom 30 and use the dynamic model and the input from the various sensors to calculate the signals 652, 654, including the vibration component 652v, 654v. In certain embodiments, the enable signal 642 is transmitted directly to the valves 350 and 450 from the controller 640.
In certain embodiments, a single system such as the hydraulic system 600 may be used on one of the hydraulic cylinders 110 (e.g., the hydraulic cylinder 1101). In other embodiments, a plurality of the hydraulic cylinders 110 may each be actuated by a corresponding hydraulic system 600. In still other embodiments, all of the hydraulic cylinders 110 may each be actuated by a system such as the system 600.
As illustrated at
Turning now to
The hydraulic valve 800 includes a spool 820 with a first configuration 822, a second configuration 824, and a third configuration 826. As illustrated, the spool 820 is at the third configuration 826. The valve 800 includes a port 804, a port 812, and a port 814. In the first configuration 822, the port 812 is blocked off, and the port 804 is fluidly connected to the port 814. In the second configuration 824, the ports 804, 812, 814 are all blocked off. In the third configuration 826, the port 804 is fluidly connected to the port 812, and the port 814 is blocked off.
In the depicted embodiment, a hydraulic line 562 connects the port 302 of the counter-balance valve 300 with the port 122 of the hydraulic cylinder 110 and with a port 902 of the valve 900. The hydraulic line 562 may include a hydraulic line 572 that extends to a control port 932 of the valve 900. The hydraulic line 572 may be a capillary line and have a delayed pressure response from the hydraulic line 562. Node 51 may include the hydraulic line 562. A hydraulic line 564 may connect the port 402 of the counter-balance valve 400 with the port 124 of the hydraulic cylinder 110 and with a port 914 of the valve 900. The hydraulic line 564 may include a hydraulic line 574 that extends to a control port 934 of the valve 900. The hydraulic line 574 may be a capillary line and have a delayed pressure response from the hydraulic line 564. Node 52 may include the hydraulic line 564. In certain embodiments, the hydraulic lines 562, 564 are included in valve blocks, housings, etc. and may be short in length. A hydraulic line 552 may connect the port 304 of the counter-balance valve 300 with the port 702 of the hydraulic valve 700 and with a port 462 of the valve 450. Node 53 may include the hydraulic line 552. Likewise, a hydraulic line 554 connects the port 404 of the counter-balance valve 400 with the port 804 of the valve 800 and with a port 362 of the valve 350. Node 54 may include the hydraulic line 554.
Sensors that measure temperature and/or pressure at various ports of the valves 700, 800 may be provided. In particular, a sensor 6101 is provided adjacent the port 702 of the valve 700. As depicted, the sensor 6101 is a pressure sensor and may be used to provide dynamic information about the system 600 and/or the boom system 10. As depicted at
In certain embodiments, pressure within the supply line 502 and/or pressure within the tank line 504 are well known, and the pressure sensors 6101 and 6102 may be used to calculate flow rates through the valves 700 and 800, respectively. In other embodiments, a pressure difference across the valve 700, 800 is calculated. For example, the pressure sensor 6103 and the pressure sensor 6102 may be used when the spool 820 of the valve 800 is at the first position 822 and thereby calculate flow through the valve 800. Likewise, a pressure difference may be calculated between the sensor 6102 and the sensor 6104 when the spool 820 of the valve 800 is at the third configuration 826. The controller 640 may use these pressures and pressure differences as control inputs.
Temperature sensors may further be provided at and around the valves 700, 800 and thereby refine the flow measurements by allowing calculation of the viscosity and/or density of the hydraulic fluid flowing through the valves 700, 800. The controller 640 may use these temperatures as control inputs.
Although depicted with the first sensor 6101, the second sensor 6102, the third sensor 6103, and the fourth sensor 6104, fewer sensors or more sensors than those illustrated may be used in alternative embodiments. Further, such sensors may be positioned at various other locations in other embodiments. In certain embodiments, the sensors 610 may be positioned within a common valve body. In certain embodiments, an Ultronics® servo valve available from Eaton Corporation may be used. The Ultronics® servo valve provides a compact and high performance valve package that includes two three-way valves (i.e., the valves 700 and 800), the pressure sensors 610, and a pressure regulation controller. The Eaton Ultronics® servo valve further includes linear variable differential transformers (LVDT) that monitor positions of the spools 720, 820, respectively. By using the two three-way proportional valves 700, 800, the pressures of the chambers 116 and 118 may be independently controlled. In addition, the flow rates into and/or out of the chambers 116 and 118 may be independently controlled. In other embodiments, the pressure of one of the chambers 116, 118 may be independently controlled with respect to a flow rate into and/or out of the opposite chambers 116, 118.
In comparison with using a single four-way proportional valve 200 (see
Turning again to
The valve 450 is also a two-way two position valve. In particular, the valve 450 includes the first port 452, the second port 462, and a third port 464. The valve 450 includes a spool 470 with a first configuration 472 and a second configuration 474. In the first configuration 472 (also depicted at
The valve 900 is a four-way two position valve. In particular, the valve 900 includes the first port 902, a second port 904, a third port 912, and the fourth port 914. The valve 900 includes a spool 920 that may be configured in a first configuration 922 (depicted at
When the pressure is applied to the control port 932, the spring 926 is compressed, and the spool 920 is urged toward the configuration 924. Likewise, when the pressure is applied to the control port 934, the spring 928 is compressed, and the spool 920 is urged toward the configuration 922. Pressure applied to the port 932 acts on an area 936. Likewise, pressure applied at the port 934 acts on an area 938. As an area 132 (e.g., a head side area) acted on by pressure within the chamber 116 may be different than an area 134 (e.g., a rod side area) acted on by pressure in the chamber 118, the areas 936, 938 may also be different and thereby compensate for the area differences between the head side 112 and the rod side 114 of the cylinder 110.
To prevent excessive shuttling of the valve 900 when the net load 90 is light, a dead-band may be defined by the valve 900. In certain embodiments, a hysteresis of the springs 926 and/or 928 ranges from about 10% to about 20% of a maximum full scale load. The maximum full scale load may be defined when either the chamber 116 or the chamber 118 is at its maximum holding capacity and supplies a corresponding pressure to the valve 900.
The valve 350 is connected to the fluid line 554 at the port 362. Likewise, the valve 450 is connected to the fluid line 552 at the port 462. A fluid line 582 connects the port 364 of the valve 350 to the port 904 of the valve 900. A node 57 may include the fluid line 582. Likewise, a fluid line 584 connects the port 464 of the valve 450 to the port 912 of the valve 900. A node 58 may include the fluid line 584. The fluid line 562 further connects to the port 902 of the valve 900. Likewise, the fluid line 564 further connects to the port 914 of the valve 900. As depicted at
The supply line 502, the return line 504, the hydraulic line 552, the hydraulic line 554, the hydraulic line 562, the hydraulic line 564, the hydraulic line 572, the hydraulic line 574, the hydraulic line 582, and/or the hydraulic line 584 may belong to a line set 550.
Turning now to
When the controller 640 sends an enable signal to the enabler 630, and the enabler 630 sends an enable signal to the valves 350, 450, the valve 350 moves to the second configuration 374, and the valve 450 moves to the second configuration 474. In certain embodiments, in the enabled configuration, the valve arrangement 840 effectively locks the hydraulic cylinder 110 from moving. In particular, regardless of the position of the valve 900, one of the valves 350 or 450 will not receive high pressure and therefore will not transmit the high pressure to the corresponding counter-balance valve 300, 400. As mentioned above, the enabled configuration of the selector valve arrangement 850 may be used to lock one of the chambers 116, 118 of the hydraulic cylinder 110 while sending vibratory pressure to an opposite one of the chambers 118, 116. The vibratory pressure may be used to counteract external vibrations encountered by the boom 30.
When the net load 90 is carried by the chamber 118, pressure from the chamber 118 is applied at the port 934 of the valve 900 and urges the valve 900 toward the first configuration 922. In the first configuration 922, the port 904 and the port 914 of the valve 900 are connected and thereby connect the node 52 with the node 57. As the valve 350 is enabled, and in the second configuration 374, the nodes 52 and 57 are further connected to the node 55. A passage for the high pressure fluid from the chamber 118 is thereby opened to the port 306 of the counter-balance valve 300. The counter-balance valve 300 is thereby opened for bi-directional flow between the ports 302 and 304. Opening up the counter-balance valve 300 to bi-directional flow allows the control valve 700 to apply and release hydraulic fluid pressure from the chamber 116 under the control of the controller 640.
When the net load 90 is carried by the chamber 116, pressure from the chamber 116 is applied at the port 932 of the valve 900 and urges the valve 900 toward the second configuration 924. In the second configuration 924, the port 902 and the port 912 of the valve 900 are connected and thereby connect the node 51 with the node 58. As the valve 450 is enabled, and in the second configuration 474, the nodes 51 and 58 are further connected to the node 56. A passage for the high pressure fluid from the chamber 116 is thereby opened to the port 406 of the counter-balance valve 400. The counter-balance valve 400 is thereby opened for bi-directional flow between the ports 402 and 404. Opening up the counter-balance valve 400 to bi-directional flow allows the control valve 800 to apply and release hydraulic fluid pressure from the chamber 118 under the control of the controller 640.
As schematically illustrated at
Turning now to
Various modifications and alterations of this disclosure will become apparent to those skilled in the art without departing from the scope and spirit of this disclosure, and it should be understood that the scope of this disclosure is not to be unduly limited to the illustrative embodiments set forth herein.
This application is a National Stage Application of PCT/US2014/037879, filed on 13 May 2014, which claims benefit of U.S. Patent Application Ser. No. 61/829,796 filed on 31 May 2013 and which applications are incorporated herein by reference. To the extent appropriate, a claim of priority is made to each of the above disclosed applications.
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