Patent Application
20150192149
This patent disclosure relates generally to hydraulic systems and, more particularly, to a hydraulic system for selectively driving two or more hydraulic actuators.
Hydraulic systems are known for converting fluid energy, for example, fluid pressure, into mechanical power. Fluid power may be transferred from one or more hydraulic pumps through fluid conduits to one or more hydraulic actuators. Hydraulic actuators may include hydraulic motors that convert fluid power into shaft rotational power, hydraulic cylinders that convert fluid power into translational motion, or other hydraulic actuators known in the art.
In an open-loop hydraulic system, fluid discharged from an actuator is directed to a low-pressure reservoir, from which the pump draws fluid. In a closed-loop hydraulic system, a pump is coupled to a hydraulic motor through a motor supply conduit and a pump return conduit, such that all of the hydraulic fluid is not returned to a low-pressure reservoir upon each pass through the closed-loop. Instead, fluid discharged from an actuator in a closed-loop system is directed back to the pump for immediate recirculation.
Japanese Publication No. 2013-036495 (hereinafter “the '495 publication”), entitled “Hydraulic Circuit for Construction Machinery,” purports to describe a hydraulic system where individual pumps in a three pump system may supply hydraulic fluid to a work actuator via a main circuit, or deliver hydraulic fluid to an accumulator circuit as a source of pilot hydraulic pressure. However, the hydraulic system of the '495 publication does not provide flexibility for directing the output of an individual pump to more than one work actuator.
Accordingly, there is a need for an improved hydraulic system to address the problems described above and/or problems posed by other conventional approaches.
In one aspect, the disclosure describes a hydraulic system. The hydraulic system includes a first pump having an outlet that is fluidly coupled to a first actuator via a first conduit, a second pump having an outlet that is fluidly coupled to a second actuator via a second conduit, a flow control module, and a controller operatively coupled to the flow control module. The flow control module is fluidly coupled to an outlet of an auxiliary pump via a third conduit, the first conduit via a fourth conduit, and the second conduit via a fifth conduit. The controller is configured to operate the flow control module in a first mode, such that the flow control module effects fluid communication between the auxiliary pump and the first actuator via the fourth conduit and blocks fluid communication between the auxiliary pump and the second actuator via the fifth conduit, and operate the flow control module in a second mode, such that the flow control module effects fluid communication between the auxiliary pump and the second actuator via the fifth conduit and blocks fluid communication between the auxiliary pump and the first actuator via the fourth conduit.
In yet another aspect, the disclosure describes a method of controlling a hydraulic system. The hydraulic system includes a first pump having an outlet that is fluidly coupled to a first actuator via a first conduit, a second pump having an outlet that is fluidly coupled to a second actuator via a second conduit, and a flow control module fluidly coupled to an outlet of an auxiliary pump via a third conduit, the first conduit via a fourth conduit, and the second conduit via a fifth conduit. The method comprising operating the flow control module in a first mode, such that the flow control module effects fluid communication between the auxiliary pump and the first actuator via the fourth conduit and blocks fluid communication between the auxiliary pump and the second actuator via the fifth conduit, and operating the flow control module in a second mode, such that the flow control module effects fluid communication between the auxiliary pump and the second actuator via the fifth conduit and blocks fluid communication between the auxiliary pump and the first actuator via the fourth conduit.
The implement system 12 may include a linkage structure coupled to hydraulic actuators, which may include linear or rotary actuators, to move the work tool 14. For example, the implement system 12 may include a boom 22 that is pivotally coupled to a body 23 of the machine 10 about a first horizontal axis (not shown), with respect to the work surface 24, and actuated by one or more double-acting, boom hydraulic cylinders 26 (only one shown in
The implement system 12 may further include a double-acting, tool hydraulic cylinder 34 that is operatively coupled between the stick 28 and the work tool 14 to pivot the work tool 14 about a third horizontal axis 36. In the non-limiting aspect illustrated in
Numerous different work tools 14 may be attached to a single machine 10 and controlled by an operator. The work tool 14 may include any device used to perform a particular task such as, for example, a bucket (shown in
The drive system 16 may include one or more traction devices powered to propel the machine 10. As illustrated in
The power source 18 may include a combustion engine such as, for example, a reciprocating compression ignition engine, a reciprocating spark ignition engine, a combustion turbine, or another type of combustion engine known in the art. It is contemplated that the power source 18 may alternatively include a non-combustion source of power such as a fuel cell, a power storage device, or another power source known in the art. The power source 18 may produce a mechanical or electrical power output that may then be converted to hydraulic power for moving the linear or rotary actuators of the implement system 12.
The operator station 20 may include devices that receive input from an operator indicative of desired maneuvering. Specifically, the operator station 20 may include one or more operator interface devices 58, for example a joystick (shown in
The head-end chamber 88 and the rod-end chamber 82 of the linear hydraulic actuator 70 may be selectively supplied with pressurized fluid or drained of fluid via the head-end port 92 and the rod-end port 94, respectively, to cause piston assembly 76 to translate within tube 72, thereby changing the effective length of the actuator to move work tool 14, for example. A flow rate of fluid into and out of the head-end chamber 88 and the rod-end chamber 82 may relate to a translational velocity of the actuator, while a pressure differential between the head-end chamber 88 and the rod-end chamber 82 may relate to a force imparted by the actuator on the work tool 14. It will be appreciated that any of the boom hydraulic cylinders 26, the stick hydraulic cylinder 32, or the tool hydraulic cylinder 34, shown in
The first actuator 102 is fluidly coupled to a first pump 106 in a first open-loop circuit 108. The first pump 106 may draw hydraulic fluid from a reservoir 110 via a conduit 112 and discharge the hydraulic fluid to a conduit 114 via a first pump outlet 116. The first open-loop circuit 108 includes a control valve assembly 118 in fluid communication with the conduit 114. The control valve assembly 118 is also in fluid communication with the head-end port 92 and the rod-end port 94 of the first actuator 102 via the conduit 120 and the conduit 122, respectively. According to an aspect of the disclosure, the reservoir 110 is in fluid communication with an ambient environment of the machine 10.
In a first configuration, the control valve assembly 118 effects fluid communication between the first pump 106 and the head-end chamber 88 of the first actuator 102 via the conduit 114 and the conduit 120, and effects fluid communication between the rod-end chamber 82 of the first actuator 102 and the reservoir 124 via the conduit 122 and the conduit 126. In a second configuration, the control valve assembly 118 effects fluid communication between the first pump 106 and the rod-end chamber 82 of the first actuator 102 via the conduit 114 and the conduit 122, and effects fluid communication between the head-end chamber 88 of the first actuator 102 and the reservoir 124 via the conduit 120 and the conduit 126. In a third configuration, the control valve assembly blocks all fluid communication between the first actuator 102 and either the first pump 106 or the reservoir 124 via the control valve assembly 118.
The first configuration and the second configuration of the control valve assembly 118 may not effect any fluid communication between the head-end chamber 88 and the rod-end chamber 82 of the first actuator 102 via the control valve assembly 118. Alternatively, the control valve assembly 118 may effect at least some fluid communication between the head-end chamber 88 and the rod-end chamber 82 of the first actuator 102 when the control valve assembly 118 is in the first configuration, the second configuration, or both.
The control valve assembly 118 may be operatively coupled to a controller 128, such that the controller 128 may cause the control valve assembly 118 to assume any of the first configuration, the second configuration, the third configuration, or other possible configurations of the control valve assembly 118. According to an aspect of the disclosure, control valve assembly 118 toggles between the first configuration, the second configuration, and the third configuration in response to a control signal from the controller 128. According to another aspect of the disclosure, the control valve assembly throttles a degree of fluid communication in the first configuration and the second configuration proportional to a control signal from the controller 128.
The reservoir 124 may be the same as the reservoir 110, or the reservoir 124 may be distinct from the reservoir 110. Further, it will be appreciated that the reservoir 124 may be distinct from the reservoir 110 but still be in fluid communication with the reservoir 110 via a flow passage, a pump, or combinations thereof.
The first pump 106 may have variable displacement, which is controlled via controller 128 to draw fluid from the reservoir 110 and discharge the fluid at a specified elevated pressure to the conduit 114. The first pump 106 may include a stroke-adjusting mechanism, for example a swashplate, a position of which is hydro-mechanically adjusted based on, among other things, a desired speed of the actuators, to thereby vary an output (e.g., a discharge rate) of the first pump 106. It is contemplated that first pump 106 may be coupled to the power source 18 in tandem (e.g., via the same shaft) or in parallel (e.g., via a gear train) with other pumps of the machine 10, as desired. Further, the displacement of the first pump 106 may be adjusted from a zero displacement position at which substantially no fluid is discharged from first pump 106, to a maximum displacement position at which fluid is discharged from first pump 106 at a maximum rate into the conduit 114 of the first open-loop circuit 108.
The first pump 106 may be directly or indirectly coupled to the power source 18 via a shaft 130. Indirect coupling between the shaft 130 of the first pump 106 and the power source 18 may include a torque converter, a gear box, an electrical circuit, or other coupling method known in the art.
Referring still to
The second actuator 104 is fluidly coupled to a second pump 136 in a second open-loop circuit 138. The second pump 136 may draw hydraulic fluid from the reservoir 110 via a conduit 140 and discharge the hydraulic fluid to a conduit 142 via a second pump outlet 144. The second open-loop circuit 138 includes a control valve assembly 146 in fluid communication with the conduit 142. The control valve assembly 146 is also in fluid communication with the head-end port 92 and the rod-end port 94 of the second actuator 104 via the conduit 148 and the conduit 150, respectively.
In a first configuration, the control valve assembly 146 effects fluid communication between the second pump 136 and the head-end chamber 88 of the second actuator 104 via the conduit 142 and the conduit 148, and effects fluid communication between the rod-end chamber 82 of the second actuator 104 and the reservoir 152 via the conduit 150 and the conduit 154. In a second configuration, the control valve assembly 146 effects fluid communication between the second pump 136 and the rod-end chamber 82 of the second actuator 104 via the conduit 142 and the conduit 150, and effects fluid communication between the head-end chamber 88 of the second actuator 104 and the reservoir 152 via the conduit 148 and the conduit 154. In a third configuration, the control valve assembly blocks all fluid communication between the second actuator 104 and either the second pump 136 or the reservoir 152 via the control valve assembly 146.
The first configuration and the second configuration of the control valve assembly 146 may not effect any fluid communication between the head-end chamber 88 and the rod-end chamber 82 of the second actuator 104 via the control valve assembly 146. Alternatively, the control valve assembly 146 may effect at least some fluid communication between the head-end chamber 88 and the rod-end chamber 82 of the second actuator 104 when the control valve assembly 146 is in the first configuration, the second configuration, or both.
The control valve assembly 146 may be operatively coupled to the controller 128, such that the controller 128 may cause the control valve assembly 146 to assume any of the first configuration, the second configuration, the third configuration, or other possible configurations of the control valve assembly 146. According to an aspect of the disclosure, control valve assembly 146 toggles between the first configuration, the second configuration, and the third configuration in response to a control signal from the controller 128. According to another aspect of the disclosure, the control valve assembly throttles a degree of fluid communication in the first configuration and the second configuration proportional to a control signal from the controller 128.
The reservoir 152 may be the same as the reservoir 110 or the reservoir 124, or the reservoir 152 may be distinct from the reservoir 110, the reservoir 124, or both. Further, it will be appreciated that the reservoir 152 may be distinct from the reservoir 110 but still be in fluid communication with the reservoir 110 via a flow passage, a pump, or combinations thereof.
The second pump 136 may have variable displacement, which is controlled via the controller 128 to draw fluid from the reservoir 110 and discharge the fluid at a specified elevated pressure to the conduit 142. The second pump 136 may include a stroke-adjusting mechanism, for example a swashplate, a position of which is hydro-mechanically adjusted based on, among other things, a desired speed of the actuators, to thereby vary an output (e.g., a discharge rate) of the second pump 136. It is contemplated that second pump 136 may be coupled to the power source 18 in tandem (e.g., via the same shaft) or in parallel (e.g., via a gear train) with other pumps of the machine 10, as desired. Further, the displacement of the second pump 136 may be adjusted from a zero displacement position at which substantially no fluid is discharged from second pump 136, to a maximum displacement position at which fluid is discharged from second pump 136 at a maximum rate into the conduit 142 of the second open-loop circuit 138.
The second pump 136 may be directly or indirectly coupled to the power source 18 via a shaft 156. Indirect coupling between the shaft 156 of the second pump 136 and the power source 18 may include a torque converter, a gear box, an electrical circuit, or other coupling method known in the art.
Referring still to
The third actuator 160 is fluidly coupled to a third pump 162 in a third open-loop circuit 164. The third pump 162 may draw hydraulic fluid from the reservoir 110 via a conduit 165 and discharge the hydraulic fluid to a conduit 166 via a third pump outlet 168. The third open-loop circuit 164 includes a control valve assembly 170 in fluid communication with the conduit 166. The control valve assembly 170 is also in fluid communication with the head-end port 92 and the rod-end port 94 of the third actuator 160 via the conduit 172 and the conduit 174, respectively.
In a first configuration, the control valve assembly 170 effects fluid communication between the third pump 162 and the head-end chamber 88 of the third actuator 160 via the conduit 166 and the conduit 172, and effects fluid communication between the rod-end chamber 82 of the third actuator 160 and the reservoir 176 via the conduit 174 and the conduit 178. In a second configuration, the control valve assembly 170 effects fluid communication between the third pump 162 and the rod-end chamber 82 of the third actuator 160 via the conduit 166 and the conduit 174, and effects fluid communication between the head-end chamber 88 of the third actuator 160 and the reservoir 176 via the conduit 172 and the conduit 178. In a third configuration, the control valve assembly blocks all fluid communication between the third actuator 160 and either the third pump 162 or the reservoir 176 via the control valve assembly 170.
The first configuration and the second configuration of the control valve assembly 170 may not effect any fluid communication between the head-end chamber 88 and the rod-end chamber 82 of the third actuator 160 via the control valve assembly 170. Alternatively, the control valve assembly 170 may effect at least some fluid communication between the head-end chamber 88 and the rod-end chamber 82 of the third actuator 160 when the control valve assembly 170 is in the first configuration, the second configuration, or both.
The control valve assembly 170 may be operatively coupled to the controller 128, such that the controller 128 may cause the control valve assembly 170 to assume any of the first configuration, the second configuration, the third configuration, or other possible configurations of the control valve assembly 170. According to an aspect of the disclosure, control valve assembly 170 toggles between the first configuration, the second configuration and the third configuration in response to a control signal from the controller 128. According to another aspect of the disclosure, the control valve assembly throttles a degree of fluid communication in the first configuration and the second configuration proportionally to a control signal from the controller 128.
The reservoir 176 may be the same as the reservoir 110, the reservoir 124, or the reservoir 152. Alternatively, the reservoir 176 may be distinct from the reservoir 110, the reservoir 124, the reservoir 152, or combinations thereof. Further, it will be appreciated that the reservoir 176 may be distinct from the reservoir 110 but still be in fluid communication with the reservoir 110 via a flow passage, a pump, or combinations thereof.
The third pump 162 may have variable displacement, which is controlled via the controller 128 to draw fluid from the reservoir 110 and discharge the fluid at a specified elevated pressure to the conduit 166. The third pump 162 may include a stroke-adjusting mechanism, for example a swashplate, a position of which is hydro-mechanically adjusted based on, among other things, a desired speed of the actuators, to thereby vary an output (e.g., a discharge rate) of the third pump 162. It is contemplated that third pump 162 may be coupled to the power source 18 in tandem (e.g., via the same shaft) or in parallel (e.g., via a gear train) with other pumps of the machine 10, as desired. Further, the displacement of the third pump 162 may be adjusted from a zero displacement position at which substantially no fluid is discharged from third pump 162, to a maximum displacement position at which fluid is discharged from third pump 162 at a maximum rate into the conduit 166 of the third open-loop circuit 164.
The third pump 162 may be directly or indirectly coupled to the power source 18 via a shaft 180. Indirect coupling between the shaft 180 of the third pump 162 and the power source 18 may include a torque converter, a gear box, an electrical circuit, or other coupling method known in the art.
Although the first actuator 102, the second actuator 104, and the third actuator 160 are shown as linear hydraulic cylinders in
As shown in
A second port 194 of the flow control module 184 is fluidly coupled to the conduit 114 at a node 196 via a conduit 198, and a third port 200 of the flow control module 184 is fluidly coupled to the conduit 142 at a node 202 via a conduit 204. A fourth port 206 of the flow control module 184 may be fluidly coupled to the conduit 166 at the node 208 via a conduit 210.
As summarized in Table 1, different operating modes of the flow control module 184 may effect different states of fluid communication between the first port 190, the second port 194, the third port 200, and the fourth port 206 of the flow control module 184. For example, a first operating mode of the flow control module 184 blocks fluid communication between the first port 190 and any of the second port 194, the third port 200, or the fourth port 206, whereas a second operating mode of the flow control module 184 effects fluid communication between the first port 190 and the second port 194 while blocking fluid communication between the first port 190 and either the third port 200 or the fourth port 206.
Thus, with reference to
†“0” indicates fluid communication is blocked and “1” indicates fluid communication is effected
According to an aspect of the disclosure, the fifth operating mode of the flow control module 184 from Table 1 effects fluid communication between second port 194 and the third port 200, as well as effecting fluid communication between the first port 190 and each of the second port 194 and the third port 200. In turn, the fifth operating mode of the flow control module 184 may effect fluid communication between the auxiliary pump 182 and the first actuator 102 and the second actuator 104 via the flow control module 184, as well as effect fluid communication between the second pump 136 and the first actuator 102 or the first pump 106 and the second actuator 104 via the flow control module 184.
However, it will be appreciated that according to another aspect of the disclosure, the fifth operating mode of the flow control module 184 from Table 1 does not effect fluid communication between the second port 194 and the third port 200. For example, according to the fifth operating mode of the flow control module 184 from Table 1, it will be appreciated that check valves, or the like, within the flow control module 184 may prevent fluid communication between the second port 194 and the third port 200 via the flow control module 184. Similarly, the sixth operating mode of the flow control module 184 may or may not effect fluid communication between the third port 200 and the fourth port 206, and the seventh operating mode of the flow control module 184 may or may not effect fluid communication between the second port 194 and the fourth port 206.
Accordingly, depending on the operating mode of the flow control module 184, flow from the outlet 188 of the auxiliary pump 182 may be delivered to various combinations of the first actuator 102, the second actuator 104, and the third actuator 160 via the conduit 198, the conduit 204, and the conduit 210, respectively. Father depending on the operating mode of the flow control module 184, fluid discharged from any of the first pump 106, the second pump 136, and the third pump 162 may be combined with fluid discharged from another of the first pump 106, the second pump 136, or the third pump 162, respectively via the flow control module 184 to supply fluid power to the first actuator 102, the second actuator 104, the third actuator 160, or combinations thereof. In addition, it will be appreciated that the flow control module 184 may effect less than all of the operating modes outlined in Table 1 without departing from the scope of the disclosure.
The auxiliary pump 182 may have variable displacement, which is controlled via the controller 128 to draw fluid from the reservoir 110 and discharge the fluid at a specified elevated pressure to the conduit 192. The auxiliary pump 182 may include a stroke-adjusting mechanism, for example a swashplate, a position of which is hydro-mechanically adjusted based on, among other things, a desired speed of the actuators, to thereby vary an output (e.g., a discharge rate) of the auxiliary pump 182. It is contemplated that the auxiliary pump 182 may be coupled to the power source 18 in tandem (e.g., via the same shaft) or in parallel (e.g., via a gear train) with other pumps of the machine 10, as desired. Further, the displacement of the auxiliary pump 182 may be adjusted from a zero displacement position at which substantially no fluid is discharged from the auxiliary pump 182, to a maximum displacement position at which fluid is discharged from auxiliary pump 182 at a maximum rate into the conduit 192. According to an aspect of the disclosure, the only connection between the outlet 188 of the auxiliary pump 182 and the hydraulic system 100 is via the conduit 192 and the flow control module 184.
The auxiliary pump 182 may be directly or indirectly coupled to the power source 18 via a shaft 211. Indirect coupling between the shaft 211 of the auxiliary pump 182 and the power source 18 may include a torque converter, a gear box, an electrical circuit, or other coupling method known in the art.
It will be appreciated that the auxiliary pump 182 may also operate as a motor when driven by pressurized fluid supplied to the inlet 232 of the auxiliary pump 182. Thus, the auxiliary pump 182 may convert shaft energy from the shaft 211 into fluid energy at the outlet port 188, or the auxiliary pump 182 may convert fluid energy applied to the inlet 232 into shaft power out through the shaft 211.
As shown in
When configured in a first position, the accumulator charge valve 222 may block fluid communication between the accumulator 214 and the head-end chamber 88 of the first actuator 102 via the accumulator charge valve 222. When configured in a second position, the accumulator charge valve 222 may effect fluid communication between the accumulator 214 and the head-end chamber 88 of the first actuator 102 via a valve flow passage 224.
The accumulator charge valve 222 may include a resilient element 226 that biases the configuration of the accumulator charge valve 222 toward the first position. The accumulator charge valve 222 may further include an actuator 228 that acts to bias the configuration of the accumulator charge valve 222 toward the second position, against the resilient element 226. Alternatively, the actuator 228 may be double-acting, and therefore capable of biasing the configuration of the accumulator charge valve toward either its first position or its second position.
The actuator 228 may be a hydraulic actuator, a pneumatic actuator, a solenoid actuator, or any other type of actuator known to persons having skill in the art. The actuator 228 may cause the configuration of the accumulator charge valve 222 to toggle between its first position and its second position. Alternatively, actuator 228 may actuate the configuration of the accumulator charge valve 222 across a spectrum of throttle positions proportional to a control signal applied to the actuator 228. It will be appreciated that the actuator 228 may be operatively coupled to the controller 128 and may be actuated by control signals transmitted therefrom.
The accumulator 214 may also be fluidly coupled to an inlet 232 of the auxiliary pump 182 via a conduit 234 and the conduit 186. The accumulator system 212 may include a check valve 235 arranged such that the accumulator 214 is not in fluid communication with any of the first pump 106, the second pump 136, the third pump 162, or the reservoir 110 via the conduit 234 along a flow direction from the accumulator 214 toward the auxiliary pump 182.
The accumulator system 212 may further include an accumulator discharge valve 236 arranged along and in series with the conduit 234. When configured in a first position, the accumulator discharge valve 236 may block fluid communication between the accumulator 214 and the inlet 232 to the auxiliary pump 182 via the accumulator discharge valve 236. When configured in a second position, the accumulator discharge valve 236 may effect fluid communication between the accumulator 214 and the inlet 232 to the auxiliary pump 182 via a valve flow passage 238.
The accumulator discharge valve 236 may include a resilient element 240 that biases the configuration of the accumulator discharge valve 236 toward the first position. The accumulator discharge valve 236 may further include an actuator 242 that acts to bias the configuration of the accumulator discharge valve 236 toward the second position, against the resilient element 240. Alternatively, the actuator 242 may be double-acting, and therefore capable of biasing the configuration of the accumulator charge valve toward either its first position or its second position.
The actuator 242 may be a hydraulic actuator, a pneumatic actuator, a solenoid actuator, or any other type of actuator known to persons having skill in the art. The actuator 242 may cause the configuration of the accumulator discharge valve 236 to toggle between its first position and its second position. Alternatively, actuator 242 may actuate the configuration of the accumulator discharge valve 236 across a spectrum of throttle positions proportional to a control signal applied to the actuator 242. It will be appreciated that the actuator 242 may be operatively coupled to the controller 128 and may be actuated by control signals transmitted therefrom.
The accumulator 214 may store hydraulic energy as a displacement of a resilient member included therein. The resilient member of the accumulator 214 may include a volume of a gas, a resilient bladder, a coil spring, a leaf spring, combinations thereof, or any other resilient member known in the art.
The third valve 306 is in fluid communication with the first port 190 via a conduit 308 and in fluid communication with the fourth port 206. The third valve 306 has a first position that blocks fluid communication between the fourth port 206 and the first port 190, the second port 194, and the third port 200 via the third valve 306. The third valve 306 also has a second position that may effect fluid communication between the fourth port 206 and the first port 190, the second port 194, the third port 200, or combinations thereof, via a valve passage 310.
The third valve 306 may include a resilient element 312 that biases the third valve 306 toward the first position. Further, the third valve 306 may include an actuator 314 that acts to bias the third valve 306 toward the second position. Alternatively, the actuator 314 may be a double-acting actuator, capable of biasing the third valve 306 toward either the first position or the second position. The actuator 314 may be a hydraulic actuator, a pneumatic actuator, a solenoid actuator, or any other actuator known to persons having skill in the art.
The actuator 314 may be operatively coupled to the controller 128, thereby allowing the controller 128 to actuate the third valve 306 according to a control signal from the controller 128. According to one aspect of the disclosure, the actuator 314 toggles a position of the third valve 306 between the first position and the second position in response to a control signal from the controller 128. According to another aspect of the disclosure, the actuator 314 varies a position of the third valve 306 over a spectrum of throttling positions between the first position and the second position, proportionally to a control signal from the controller 128.
The second valve 304 is in fluid communication with the first port 190 via a conduit 316 that is fluidly coupled to the conduit 308 at a node 318, and the second valve 304 is in fluid communication with the third port 200. The second valve 304 has a first position that blocks fluid communication between the third port 200 and the first port 190, the second port 194, and the fourth port 206 via the second valve 304. The second valve 304 also has a second position that may effect fluid communication between the third port 200 and the first port 190, the second port 194, the fourth port 206, or combinations thereof, via a valve passage 320.
The second valve 304 may include a resilient element 322 that biases the second valve 304 toward the first position. Further, the second valve 304 may include an actuator 324 that acts to bias the second valve 304 toward the second position. Alternatively, the actuator 324 may be a double-acting actuator, capable of biasing the second valve 304 toward either the first position or the second position. The actuator 324 may be a hydraulic actuator, a pneumatic actuator, a solenoid actuator, or any other actuator known to persons having skill in the art.
The actuator 324 may be operatively coupled to the controller 128, thereby allowing the controller 128 to actuate the second valve 304 according to a control signal from the controller 128. According to one aspect of the disclosure, the actuator 324 toggles a position of the second valve 304 between the first position and the second position in response to a control signal from the controller 128. According to another aspect of the disclosure, the actuator 324 varies a position of the second valve 304 over a spectrum of throttling positions between the first position and the second position, proportionally to a control signal from the controller 128.
The first valve 302 is in fluid communication with the first port 190 via a conduit 326 that is fluidly coupled to the conduit 308 at a node 328, and the first valve 302 is in fluid communication with the second port 194. The first valve 302 has a first position that blocks fluid communication between the second port 194 and the first port 190, the third port 200, and the fourth port 206 via the first valve 302. The first valve 302 also has a second position that may effect fluid communication between the second port 194 and the first port 190, the third port 200, the fourth port 206, or combinations thereof, via a valve passage 330.
The first valve 302 may include a resilient element 332 that biases the first valve 302 toward the first position. Further, the first valve 302 may include an actuator 334 that acts to bias the first valve 302 toward the second position. Alternatively, the actuator 334 may be a double-acting actuator, capable of biasing the first valve 302 toward either the first position or the second position. The actuator 334 may be a hydraulic actuator, a pneumatic actuator, a solenoid actuator, or any other actuator known to persons having skill in the art.
The actuator 334 may be operatively coupled to the controller 128, thereby allowing the controller 128 to actuate the first valve 302 according to a control signal from the controller 128. According to one aspect of the disclosure, the actuator 334 toggles a position of the first valve 302 between the first position and the second position in response to a control signal from the controller 128. According to another aspect of the disclosure, the actuator 334 varies a position of the first valve 302 over a spectrum of throttling positions between the first position and the second position, proportionally to a control signal from the controller 128.
As summarized in Table 2, different operating modes of the flow control module 300 effect different states of fluid communication between the first port 190, the second port 194, the third port 200, and the fourth port 206 of the flow control module 300. For example, a first operating mode of the flow control module 300 blocks fluid communication between the first port 190 and any of the second port 194, the third port 200, or the fourth port 206 by closing the first valve 302, the second valve 304, and the third valve 306, whereas a second operating mode of the flow control module 184 effects fluid communication between the first port 190 and the second port 194 by opening the first valve 302 while blocking fluid communication between the first port 190 and either the third port 200 or the fourth port 206 by closing the second valve 304 and the third valve 306.
According to an aspect of the disclosure, the fifth operating mode of the flow control module 300 from Table 2 effects fluid communication between second port 194 and the third port 200, as well as effecting fluid communication between the first port 190 and each of the second port 194 and the third port 200 by opening the first valve 302 and the second valve 304. However, it will be appreciated that check valves, or the like, could optionally be added to the flow control module 300, such that the fifth operating mode of the flow control module 300 from Table 1 does not effect fluid communication between the second port 194 and the third port 200.
Similarly, the sixth operating mode of the flow control module 300 may or may not effect fluid communication between the third port 200 and the fourth port 206, and the seventh operating mode of the flow control module 300 may or may not effect fluid communication between the second port 194 and the fourth port 206. Further, an “open” valve configuration, as indicated in
Although
The control valve assembly 118 may further include a check valve 364 disposed in series fluid communication with the conduit 114. The check valve 364 may prevent flow through the conduit 114 in a direction away from the node 360, but allow flow through the conduit 114 in a direction toward the node 360.
The first valve 350 is also in fluid communication with the conduit 120 via the node 366, and the second valve 352 is also in fluid communication with the conduit 122 via the node 368. Each of the first valve 350 and the second valve 352 may be actuated according to a control signal from the controller 128 to open or close the valves. Thus, when the first valve 350 is configured in an open position, the first pump 106 (see
Conversely, when the first valve 350 is configured in a closed position, the first pump 106 (see
Referring still to
Thus, when the third valve 354 is configured in an open position, the head-end chamber 88 of the first actuator 102 (see
According to an aspect of the disclosure, a valve position or degree of throttling through each of the third valve 354 and the fourth valve 356 may be proportional to an attribute of a control signal from the controller 128. According to another aspect of the disclosure, a valve position of the third valve 354 or the fourth valve 356 may toggle between a closed position and a wide open position in response to a change in an attribute of the control signal from the controller 128.
The control valve assembly 118 may further include a check valve 386 disposed in series fluid communication with the conduit 380 between the node 378 and the node 372. The check valve 386 may prevent flow through the conduit 380 in a direction from the node 378 toward the node 372, but allow flow through the conduit 380 in a direction from the node 372 toward the node 378. The control valve assembly 118 may further include a check valve 388 disposed in series fluid communication with the conduit 384 between the node 382 and the node 376. The check valve 388 may prevent flow through the conduit 384 in a direction from the node 382 toward the node 376, but allow flow through the conduit 384 in a direction from the node 376 toward the node 382. It will be appreciated that the check valve 386 and the check valve 388 may provide makeup flow from the reservoir 124 to a corresponding actuator via the conduit 120 and the conduit 122, respectively, independent of the operating state of the first valve 350, the second valve 352, the third valve 354, or the fourth valve 356.
Referring now to both
The control valve assembly 118 may include a pressure transducer 390 and a pressure transducer 392 in fluid communication with the head-end chamber 88 and the rod-end chamber 82 of the first actuator 102, respectively. Further, the controller 128 may be operatively coupled to the pressure transducer 390 and the pressure transducer 392 and use the pressure signals therefrom to determine whether the first actuator 102 is performing work against a load, operating in an overrun condition, or make other use of the pressure signals known in the art.
Although a particular configuration of the control valve assembly 118 is shown in
The present disclosure may be applicable to any machine including a hydraulic system containing two or more hydraulic actuators. Aspects of the disclosed hydraulic system and method may promote operational flexibility, performance, and energy efficiency of multi-actuator hydraulic systems.
Applicants discovered that a conventional approach of combining the outputs of multiple pumps into a common manifold before distributing the fluid power to individual actuators may result in so-called cross-modulation losses. Cross-modulation losses are incurred when multiple actuators having different pressure demands are supplied by a single fluid source at a single pressure. For example, a manifold may be operated at a high pressure to satisfy the demand of one of several actuators in a hydraulic system at a given point in time. Then, at that same point in time, additional throttling may be required to sustain control over the actuators with lower pressure demands. In turn, the high degree of throttling to supply the low demand actuators may result in higher system power loss than if the individual actuators were supplied by separate fluid sources with more closely tailored supply pressures.
According to an aspect of the disclosure shown in
According to an aspect of the disclosure, with reference to
One or more corresponding signals generated by the interface device 58 may be provided to the controller 128 (see
The controller 128 may further include functionality for estimating the power demand for hydraulic actuators at points in time through a duty cycle. Then based on a comparison of estimated actuator power demand to the rated capacities of the corresponding dedicated pumps, the controller 128 may configure the flow control module 184 to advantageously allocate hydraulic pump outputs to the individual hydraulic actuators to promote system performance and energy efficiency throughout the duty cycle.
A duty cycle of the machine 10 may include a dig function, whereby material may be loaded from a source location into the bucket by a scooping motion of the bucket; a lift and swing function, whereby material is lifted from its source location and translated close to a target location; a dump function, whereby the material is deposited from the bucket to the target location; and a return function, whereby the bucket may be returned to the source location. The dig function, the lift and swing function, the dump function, and the return function may each benefit from simultaneous operation of more than one of the boom hydraulic cylinder 26, the stick hydraulic cylinder 32, and the tool hydraulic cylinder 34 at a given point in time.
Performance of these functions may benefit from transmission of hydraulic power to one of the boom hydraulic cylinder 26, the stick hydraulic cylinder 32, and the tool hydraulic cylinder 34 in excess of the capacity of the actuators' dedicated pump, namely the first pump 106, the second pump 136, and the third pump 162, respectively. Conversely, the power demand for some actuators during a particular function may be less than that actuator's dedicated pump capacity, thereby resulting in unused pump capacity at that time.
For example, during the dig function the power demand for the stick hydraulic cylinder 32 may exceed the rated capacity of its dedicated second pump 136, while the power demand for the boom hydraulic cylinder 26 and the tool hydraulic cylinder 34 may be less than their corresponding dedicated pump's capacity. Similarly, during the lift function the power demand for the boom hydraulic cylinder 26 may exceed the rated capacity of its dedicated first pump 106, while the power demand for the stick hydraulic cylinder 32 and the tool hydraulic cylinder 34 may be less than their corresponding dedicated pump's capacity.
As discussed above, aspects of the disclosure provide a flow control module 184 that is configured to selectively allocate fluid power from an auxiliary pump 182 to supplement the power output of a pump dedicated to a particular hydraulic actuator. Table 3 shows a pump allocation schedule for a digging duty cycle of the hydraulic system 100, according to an aspect of the disclosure.
For example, during the dig function when the stick power demand is high, the controller 128 may cause the flow control module 184 to operate in its third operating mode (see Table 1) to effect fluid communication between the auxiliary pump 182 and the stick hydraulic cylinder 32 via the first port 190 and the third port 200. Further, during the lift function when the boom power demand is high, the controller 128 may cause the flow control module 184 to operate in its second operating mode (see Table 1) to effect fluid communication between the auxiliary pump 182 and the boom hydraulic cylinder 26 via the first port 190 and the second port 194.
Table 4 shows a pump allocation schedule for a digging duty cycle of the hydraulic system 100, according to another aspect of the disclosure. The pump allocation schedule summarized in Table 4 is similar to that summarized in Table 3, except that during the lift function the controller 128 may cause the flow control module 184 to operate in its fifth mode to effect fluid communication between the auxiliary pump 182 and the second pump 136 with the boom hydraulic cylinder 26 via the first port 190, the second port 194, and the third port 200. Accordingly, the fluid output from the second pump 136 may be shared between the stick hydraulic cylinder 32 and the boom hydraulic cylinder 26 when the flow control module 184 is operated in its fifth mode (see Table 1).
Referring to
Further, the controller 128 may selectively open the accumulator discharge valve 236 to apply the fluid energy stored in the accumulator 214 to the inlet 232 of the auxiliary pump 182, thereby effectively increasing the flow, pressure, or both of fluid at the outlet 188 of the auxiliary pump 182 above a level attained with the accumulator discharge valve 236 closed. The opening of the accumulator discharge valve 236 may be conditioned upon a pressure in the accumulator 214 exceeding a threshold pressure, where the controller 128 may assess the pressure in the accumulator 214 via a pressure transducer 394 disposed in fluid communication with the accumulator 214. Further, the opening of the accumulator discharge valve 236 may also be conditioned upon an operating mode of the flow control module 184, a position of an actuator within the hydraulic system 100, pressures sensed from one of the control valve assemblies 118, 146, 170, or any other performance or state variable of the machine 10 known in the art.
Accordingly, aspects of the disclosure enable flexible and efficient allocation of multiple pumps to two or more hydraulic actuators while minimizing or eliminating cross-modulation losses associated with conventional common manifold approaches. Further, the flexibility of pump allocation provided by aspects of the disclosure may enable a reduction in the capacities of the individual pumps in the system, and may enable either downsizing the power source 18 driving the pumps or operating the power source 18 at a lower speed, thereby decreasing fuel consumption for the same amount of work performed by the machine 10. Moreover, the hydraulic system 100 may utilize the accumulator system 212 to advantageously store fluid energy in the accumulator 214 and selectively discharge the stored fluid energy to an actuator via the auxiliary pump 182.
It will be appreciated that the foregoing description provides examples of the disclosed system and technique. However, it is contemplated that other implementations of the disclosure may differ in detail from the foregoing examples. All references to the disclosure or examples thereof are intended to reference the particular example being discussed at that point and are not intended to imply any limitation as to the scope of the disclosure more generally. All language of distinction and disparagement with respect to certain features is intended to indicate a lack of preference for those features, but not to exclude such from the scope of the disclosure entirely unless otherwise indicated.
Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context.
Throughout the disclosure, like reference numbers refer to similar elements herein, unless otherwise specified.
