Hydraulic circuit including hydraulic pressure reduction energy recovery

[0042] reference resources Figure 1 , oscillating hydraulic system 1 includes hydraulic circuit 2. The hydraulic circuit 2 includes an actuator 40 that performs work and a prime mover 10 that controls the flow of hydraulic fluid to the actuator 40. As used herein, the term "hydraulic fluid" refers to the fluid in hydraulic circuit 2. In the illustrated embodiment, the hydraulic fluid is oil, but is not limited thereto. The hydraulic circuit 2 also includes a recovery device 80 arranged between the prime mover 10 and the actuator 40 in the hydraulic circuit 2. The recovery device 80 allows the oscillating hydraulic system 1 to avoid hydraulic locking by allowing the high-pressure side of the actuator to depressurize immediately before reversing the actuation direction. In addition, the recovery device 80 allows the hydraulic system to capture (recover) reduced pressure energy for subsequent use by the hydraulic system, as discussed in detail below.

[0043] Prime mover 10 may be any hydraulic source configured to generate an oscillating flow of hydraulic fluid between two fluid ports of prime mover 10, such as prime mover a port 13 and prime mover B port 14. In the illustrated embodiment, the prime mover 10 includes a fixed displacement bidirectional pump 12 driven by a variable speed electric motor 11. Electric motor 11 controls the speed and direction of pump 12. The pump 12 includes a pump a port 12a, which is connected to the prime mover a port 13 and the a port 43 of the actuator 40 via the first fluid line 3 of the hydraulic circuit 2. In addition, the pump 12 includes a pump B port 12b, which is connected to the prime mover B port 14 and the B port 44 of the actuator 40 via the second fluid line 4.

[0044] The prime mover 10 includes a pressure relief device 25 connected to the first and second fluid lines 3, 4 via the first and second check valves 16, 17 and therefore to the pump 12. The pressure relief device 25 includes a pair of adjustable pressure relief valves 19 and 20, which are configured to prevent damage to circuit components due to overpressure of the hydraulic circuit 2.

[0045] The prime mover 10 includes a constant pressure source, such as a charge pump 30 driven by an electric motor 31 and connected to the first and second fluid lines 3 and 4 via check valves 16 and 17. Filling pump 30 maintains lines 3 and 4 at P min Under the minimum pressure. Charging pump 30 draws its fluid from main accumulator 15. The main accumulator 15 is a low-pressure, inflated expansion tank sized to store the volume of excess hydraulic fluid from the actuator 40, prime mover 10 and recovery device 80 during operation and in the de energized state. The filling pump 30 supplies the hydraulic circuit 2 with a pressure corresponding to the minimum pressure P min To accommodate leakage in hydraulic circuit 2 and maintain the hydraulic circuit pressure at the desired nominal value.

[0046] The prime mover 10 includes a flushing device 28 connected in parallel with the pressure relief device 25 to the first and second fluid lines 3, 4 and configured to remove heat from the hydraulic circuit 2. The flushing device 28 includes a pair of pilot operated check valves 22, 23 and is connected to a reservoir, such as a main accumulator 15, via a check valve 18 and a filter 21.

[0047] The actuator 40 may be any actuator capable of receiving an oscillating flow of hydraulic fluid from the prime mover 10 and generating an oscillating motion from the oscillating flow to perform work. In the illustrated embodiment, the actuator 40 is a two rod hydraulic cylinder 41, which includes a cylinder housing 42 and a piston 45 arranged in the cylinder housing 42. The piston 45 forms a seal with the cylinder housing 42 and separates the internal space of the cylinder housing 42 into a first chamber 54 including the actuator a port 43 and a second chamber 55 including the actuator B port 44. The cylinder 41 includes a first rod 48 disposed in the first chamber 54. The first end 49 of the first rod 48 is connected to one side of the piston 45, and the second end 50 of the first rod 48 extends from the cylinder housing 42 and is configured to be connected to the load. In addition, the cylinder 41 includes a second rod 51 provided in the second chamber 55. The first end 52 of the second rod 51 is connected to the side opposite to the side of the piston 45, and the second end 53 of the second rod 51 is configured to be connected to the load. In some embodiments, the first and second rods 48, 51 are connected to the same load. In other embodiments, the first rod 48 is connected to the first load, and the second rod 51 is connected to a second load different from the first load.

[0048] The speed and direction of the actuator 40 are a function of the angular speed of the electric motor 11 and the displacement of the pump 12.

[0049] The actuator 40 is a linear actuator configured to provide oscillating motion between a forward stroke in a first direction (see arrow 56) and a retraction stroke in a second direction opposite to the first direction (see arrow 58). reference resources Figure 1 , the forward stroke corresponds to the movement of the piston 45 in the first direction 56 in the cylinder housing 42, for example, from side a to side B, or relative to the cylinder housing 42 Figure 1 The orientation shown in moves from left to right. The retraction stroke corresponds to the movement of the piston 45 in the second direction 58 in the cylinder housing 42, for example, from side B to side a, or relative to the cylinder housing 42 Figure 1 The orientation shown in moves from right to left. In addition, the actuator 40 is configured to be connected to the load in each of the forward stroke and the retraction stroke, and the movement is realized by the hydraulic fluid provided by the prime mover 10 via the first and second fluid lines 3 and 4.

[0050] In the arrangement in which the recovery device 80 is omitted from the hydraulic circuit 2, the pressure gradually increases in the first fluid line 3 connecting the prime mover a port 13 to the actuator a port 43 as the actuator 40 advances (for example, the piston 45 moves from the a side to the B side).

[0051] As the piston 45 advances, the volume of the first chamber 54 increases and the amount of hydraulic fluid in the system, such as the system volume v system , due to the movement of piston 45 in cylinder housing 42, it increases in proportion to the increased volume of first chamber 54. In order to move the load, the volume added to chamber 54 must be at a relatively high pressure P s 。 Prime mover 10 is adding fluid volume to hydraulic circuit 2 and reducing the hydraulic circuit pressure from minimum pressure P min Raise to higher pressure P s 。 Therefore, for each position of the cylinder, a volume equal to the minimum volume V must be drawn from pump port 12b min And compress it to system volume V at pump port 12a system 。 System volume V in chamber 55 system In the case of less than or equal to the system volume of the first chamber 54, the additional fluid must come from the main accumulator 15.

[0052] When the actuator 40 reaches the B-side reverse position of the piston stroke, the system volume V of the first chamber 54 system Greater than the system volume V of the second chamber 55 system 。 In order to reverse the actuator 40 and do work in the opposite direction, the first chamber 54 needs to be reduced to close to the minimum pressure P min And the second chamber 55 needs to be raised to a higher pressure P s 。 Since the volumes of the first and second chambers 54 and 55 are not equal, the additional compressed volume V of the second chamber 55 c Lower than the additional compressed volume V contained in the first chamber 54 c 。 This means that it is not possible to simply compress the additional volume V of the second chamber 55 c Move to the first chamber 54 to achieve pressure reversal. If the additional compressed volume V in the first chamber 54 c Without being drained or displaced, the pressure in the first chamber 54 will not approach the minimum value P min 。 Since the pressure in the first chamber 54 is opposite to the pressure in the second chamber 55, for a given load, it is higher than the minimum value p relative to the pressure remaining in the first chamber 54 min The remaining pressure of the second chamber 55, the higher pressure P required by the second chamber 55 s Will increase. When the required higher pressure P s Greater than the maximum allowable pressure of circuit 2, the result is hydraulic lockout.

[0053] In order to avoid hydraulic locking, the pressure in the first chamber 54 must change from the higher pressure P during the retraction stroke s Reduce to near minimum pressure P min 。 This can only be achieved by allowing the fluid in the first chamber 54 to expand to the minimum volume v min To achieve. In the hydraulic circuit omitting the recovery device 80, this expansion can be achieved by discharging the corresponding hydraulic fluid, thereby wasting the associated compression energy. Once the first chamber 54 is depressurized, the force generated in the second chamber 55 may exceed the force generated in the first chamber 54 by a sufficient amount to move the load, allowing the actuator 40 to reverse the direction and perform a retraction stroke.

[0054] The same is true during the reverse stroke (for example, when piston 45 moves from side B to side a). When the actuator 40 is retracted, the pressure gradually increases in the second fluid line 4 connecting the prime mover B port 14 to the actuator B port 44. Due to the movement of piston 45 in cylinder housing 42, the volume of second chamber 55 increases and the amount of hydraulic fluid added to second chamber 55 (V system ）Increases in proportion to the increased volume of the second chamber 55. In order to move the load, the volume added to the second chamber 55 must be at a higher pressure P s 。 The prime mover 10 adds a corresponding volume of fluid and reduces the pressure of the second chamber 55 from the minimum pressure P min Raise to higher pressure P s。 Therefore, for a given position of piston 45 in cylinder housing 42, it must be extracted from pump a port 12a equal to the minimum volume v min And compress it to system volume V at pump B port 12b system 。 The system volume V in the first chamber 54 system Less than or equal to the system volume V of the second chamber 55 system In this case, additional fluid must come from main accumulator 15.

[0055] When the actuator 40 reaches the A-side reverse position of the piston stroke, the system volume V of the second chamber 55 system Greater than the system volume V of the first chamber 54 system 。 In order to reverse the actuator 40 and do work in the opposite direction, the pressure in the second chamber 55 needs to be reduced to close to the minimum pressure P min And it is necessary to raise the pressure in the first chamber 54 to a higher pressure P s 。 Since the volumes of the first and second chambers 54 and 55 are not equal, the additional compressed volume V of the first chamber 54 c Lower than the additional compressed volume V contained in the second chamber 55 c 。 This means that it is not possible to simply compress the additional volume V of the first chamber 54 c Move to the second chamber 55 to achieve pressure reversal. If the additional compressed volume V in the second chamber 55 c Without being drained or displaced, the pressure in the second chamber 55 will not approach the minimum pressure P min 。 Since the pressure in the second chamber 55 is opposite to the pressure in the first chamber 54, for a given load, it is higher than the minimum pressure P relative to the pressure remaining in the second chamber 55 min The amount of residual pressure, the higher pressure P required for the first chamber 54 s Will increase. When the required higher pressure P s When the pressure is greater than the maximum allowable pressure of hydraulic circuit 2, the result is hydraulic lockout.

[0056] In the illustrated embodiment, the recovery device 80 is arranged between the prime mover 10 and the actuator 40 in the hydraulic circuit 2. The recovery device 80 is configured to capture and store hydraulic fluid displaced from the actuator 40 during operation of the prime mover 10. In particular, the recovery device 80 is configured to allow the volume of the first and second chambers 54, 55 to change from the system volume v system Expand to near minimum volume V min This allows the pressure in each chamber to be reduced from the higher pressure P s Reduce to near minimum pressure P min Predetermined pressure.

[0057] The recovery device 80 includes a first recovery module 81 and a second recovery module 88. The first recovery module 81 is connected to the first fluid line 3 via the first branch line 5. The first branch line 5 is connected to the first fluid line 3 at a position between the prime mover a port 13 and the actuator a port 43.

[0058] The first recovery module 81 includes a first recovery accumulator 82 connected to the end of the first branch line 5 and a first control valve 83 arranged in the first branch line 5 between the first recovery accumulator 82 and the first fluid line 3.

[0059] The second recovery module 88 is connected to the second fluid line 4 via the second branch line 6. The second branch line 6 is connected to the second fluid line 4 at a position between the prime mover B port 14 and the actuator B port 44.

[0060] The second recovery module 88 includes a second recovery accumulator 89 connected to the end of the second branch line 6 and a second control valve 90 arranged in the second branch line 6 between the second recovery accumulator 89 and the second fluid line 4.

[0061] In some embodiments, the electric motor 11 and the valves 19, 20, 22, 23, 83, 90 may be controlled by a general purpose programmable controller (not shown), such as a programmable logic controller (PLC). The PLC may include an input module or point, a central processing unit (CPU), and an output module or point. The PLC receives information from the connected input devices and sensors, processes the received data, and triggers the required output according to its pre programmed instructions. The instructions executed by the PLC can be provided by the programming device or stored in the nonvolatile PLC memory.

[0062] In the hydraulic circuit 2 including the recovery device 80, as the actuator 40 advances, the piston 45 moves from side a to side B in the cylinder housing 42. As the piston 45 moves, the first control valve 83 closes and the second control valve 90 opens, and the pressure gradually increases in the first fluid line 3 between the prime mover a port 13 and the actuator a port 43.

[0063] As piston 45 advances, the system volume V of first chamber 54 increases system Increases, and therefore the corresponding additional compressed volume V of the first chamber 54 c This increases the minimum volume V required to extract fluid from pump B port 12b min And compress it into the first chamber 54. System volume V system And additional compressed volume V c Both increase, and therefore, due to the movement of piston 45 in cylinder housing 42, the minimum volume v min Increases in proportion to the increased volume of the first chamber 54.

[0064] When actuator 40 reaches the reverse position on side B of the piston stroke, it is equal to the minimum volume v min The volume of has changed from the minimum pressure P min To higher pressure P s Compressed to system volume V system 。 After the forward movement stops, but before reversing, the second control valve 90 is closed and the first control valve 83 is opened, allowing the volume in the first chamber 54 to expand into the device 82. The minimum pressure of the first recovery accumulator 82 is the minimum pressure P min And the first recovery accumulator 82 is appropriately sized to have a certain gas fluid ratio to allow the system volume V of the first chamber 54 system Increase, thereby reducing the pressure in the first chamber 54 above the minimum pressure P min However, it is low enough to avoid the nominal value of hydraulic locking. System volume V system The increase in corresponds to the additional compressed volume V added to the first chamber 54 during the forward stroke c And therefore v system Very close to the minimum volume V min 。 Due to the compressibility of the fluid, this volume expansion causes the pressure to drop very close to the minimum pressure P in chamber 54 min 。 When the first chamber 54 is depressurizing, the pump 12 is temporarily suspended. When the pressure of the first fluid line 3 stabilizes to the desired nominal value, the prime mover 10 is restarted to direct the fluid to the prime mover B port 14, and the actuator 40 can be reversed due to the greater force generated in the second chamber 55. When the piston 45 moves through the retraction stroke, the second control valve 90 remains open, allowing the use of the energy stored in the first recovery accumulator 82 by supplying the additional compressed volume V in the second chamber 55 from the accumulator instead of the auxiliary charging pump 30 c 。

[0065] As piston 45 retracts, the system volume V of second chamber 55 system And the corresponding additional compressed volume v c Also increased. The recovery device pressure of the first recovery accumulator 82 is maintained above the minimum pressure P min Any additional compressed volume V for the second chamber 55 c Will be supplied from the first recovery accumulator 82.

[0066] When the actuator 40 reaches the A-side reverse position of the piston stroke, the system volume V of the second chamber 55 system It approaches its maximum value and therefore requires an additional compressed volume V of the second chamber 55 c Maximum value of. Therefore, when the piston 45 moves from side B to side a in the cylinder housing 42, the increased volume in the second chamber 55 consumes the energy stored in the first recovery accumulator 82. This energy consumption is achieved by reducing the required volume of fluid that needs to be supplied to the circuit via the filling pump 30. When the pressure in the first recovery accumulator 82 has been reduced to the desired nominal value (E. G., corresponding to the pressure provided by the charging pump 30, e. G., the minimum pressure P min ）The energy stored in the first recovery accumulator 82 has been exhausted and the first control valve 83 is closed.

[0067] The same applies to the subsequent forward movement of piston 45 from side a to side B (for example, from right to left, subsequent retraction movement). After the movement from side B to side a stops, but before reversing, the first control valve 83 remains closed and the second control valve 90 is opened, allowing the second chamber 55 to flow from the second chamber 55 to the second recovery accumulator 89 via hydraulic fluid, and the decompression corresponds to the additional compression volume v c Amount of. When the second chamber 55 is depressurizing, the pump 12 is temporarily suspended. When the pressure of the second fluid line 4 stabilizes above but close to the minimum pressure P min The prime mover 10 is restarted to direct fluid from the prime mover a port 13, and the actuator 40 can be reversed due to the greater force generated in the first chamber 54. When piston 45 moves through the forward stroke, second control valve 90 remains open.

[0068] The increased volume in the first chamber 54 also increases the additional compressed volume V of the first chamber c , as piston 45 advances from side a to side B, this will consume the energy stored in the second recovery accumulator 89. This energy consumption is achieved by reducing the torque on motor 11 due to the increase in pressure on accumulator B port 44. When the pressure of the second recovery accumulator 89 has been reduced to the desired nominal value, the stored energy has been exhausted and the second valve 90 can be closed.

[0069] The volume of the fluid trapped in the actuator 40 is thus allowed to increase while the volume of the fluid trapped in the actuator 40 is reversed to a previously stored volume, thereby allowing the volume of the fluid to be reduced. In addition, the recovery device 80 also reduces the hydraulic shock associated with rapid decompression. Each time the piston 45 reverses in the cylinder housing 42, the hydraulic circuit pressure first decreases through the additional compression volume V corresponding to one of the first and second recovery modules 81 and 88 c Associated pressure attenuation.

[0070]A variant that can save more energy than the above system but depends on the ability to increase the total pressure on ports 13 and 14 of prime mover A and B can be realized by reversing the action of the first and second control valves 83 and 90 and increasing the precharge in the first and second recovery accumulators 82 and 89 to very close to the higher pressure P s Value of. The operation of this variant is as follows.

[0071] As the actuator 40 moves toward the B-side reverse position, the first control valve 83 opens and the second control valve 90 closes. When actuator 40 reaches the reverse position on side B of the piston stroke, it is equal to the minimum volume v min The volume of has changed from the minimum pressure P min To higher pressure P s Compressed to system volume V system 。 After the forward movement stops but before reversing, the first control valve 83 is closed and the second control valve 90 is opened. Since the fluid enters the system from 82, this will balance the pressure in fluid line 4 to slightly less than the higher pressure P s Pressure. The reversal of prime mover 10 will allow the first chamber 54 to be depressurized. This will cause an increase in pressure in the second chamber 55 and a decrease in pressure in the first chamber 54. The second recovery accumulator 89 is sized to have a gas fluid ratio sufficient to allow an additional compressed volume V close to or equal to the first chamber 54 c The fluid volume enters the second recovery accumulator 89. The second recovery accumulator 89 is designed so that the pressure in the second chamber 55 can rise sufficiently higher than the pressure in the first chamber 54 to allow movement without exceeding the maximum system pressure, thereby avoiding hydraulic locking. When the pressure in the second chamber 55 is sufficiently higher than that in the first chamber 54, the actuator 40 will begin to move in the opposite direction. Volume expansion on the high-pressure side is allowed, and the additional compressed volume V is allowed at the lowest possible pressure increment across prime mover 10 c Transfer from the first chamber 54 to the second chamber 55. When piston 45 moves through the retraction stroke, second control valve 90 remains open. As the piston 45 moves, the energy stored in the second recovery accumulator 89 is used to help the piston 45 move from B to a, thereby allowing the use of the energy stored in the second recovery accumulator 89 in this way.

[0072] In this variant, when the actuator 40 reaches the A-side reverse position of the piston stroke, the pressure in the first chamber 54 is equal to the minimum pressure P min Thus, the required pressure in the second chamber 55 is reduced to a higher pressure P s 。 When the second chamber 55 is at the nominal higher pressure P s When operating in the lower position, the second control valve 90 can be closed and all stored energy has been used. In this application, energy savings are achieved by transferring the energy used to compress the fluid in the first chamber 54 to the second recovery accumulator 89 at a low pressure drop across the prime mover 10 during reverse rotation, thereby reducing the torque on the motor 11 required to move the potential energy from the prime mover a port 13 to the prime mover B port 14.

[0073] The same applies to the subsequent forward movement of piston 45 from side a to side B (for example, from right to left, subsequent retraction movement). After the retraction movement from side B to side a stops, but before reversing, the first control valve 83 is opened and the second control valve 90 remains closed, so that the pressure in the first and second chambers 54 and 55 is close to equilibrium. When the pressure of the second fluid line 4 stabilizes to close to the higher pressure P s At the desired nominal value of, prime mover 10 is restarted to direct fluid to prime mover a port 13. This allows prime mover 10 to compress the additional volume V of fluid c Transfer from side B to side a, starting at nearly equal pressure and ending with a pressure drop sufficient to move the load in the opposite direction. Therefore, it is allowed to compress the additional volume V at the lowest possible pressure drop c Transfer from one side of hydraulic circuit 2 to the other. The actuator 40 can be reversed due to the higher force generated in the first chamber 54. When piston 45 moves through the forward stroke, first control valve 83 remains open.

[0074] The increased volume in the first chamber 54 also increases the additional compressed volume V of the first chamber c , this will consume the remaining additional compressed volume V in the second chamber 55 c And finally reduce the second chamber pressure to the minimum pressure P min 。 When the second chamber 55 reaches the minimum pressure P min When, the required pressure in the first chamber 54 will reach the nominal higher pressure P s 。 Due to the low pressure required in the first chamber 54, the fluid will leave the first recovery accumulator 82, thereby consuming the energy stored in the first recovery accumulator 82. This energy consumption is achieved by adding an additional compressed fluid v c This is achieved by reducing the pressure drop compressed into the movable chamber. When the pressure of the first recovery accumulator 82 has been reduced to the desired nominal value, the stored energy has been exhausted and the first valve 83 can be closed.

[0075] Therefore, the recovery device 80 allows a lower system volume V at the end of the actuator 40 system The volume on one side of the is increased, allowing the high pressure to be added to the compressed volume v cTransfer from one working port to another and capture part of the potential energy stored in the compressed fluid during inversion. In addition, the recovery device 80 also reduces the hydraulic shock associated with rapid decompression. Each time the piston 45 reverses in the cylinder housing 42, the hydraulic circuit pressure is first balanced, and then the compression volume V is added c It is transferred to the corresponding one of the first and second recovery modules 81 and 88.

[0076] Although the hydraulic system 1 includes a recovery device 80 arranged in the hydraulic circuit 2 between the prime mover 10 and the actuator 40, the hydraulic system 1 and the hydraulic circuit 2 are not limited to using Figure 1 Specific embodiments of prime mover 10 and actuator 40 shown in. It should be understood that other prime movers and actuators can be replaced Figure 1 The prime mover 10 and the actuator 40 shown in Fig. 1, as long as the resulting hydraulic system 1 generates an oscillating motion and is configured to be connected to the load in both directions of the oscillating motion. Reference will now be made Figure 2-5 Three non limiting examples of alternative embodiments of a hydraulic system including a recovery device 80 are described.

[0077] reference resources Figure 2 and Figure 3 , the hydraulic system 201 of the alternative embodiment includes a hydraulic circuit 202. The hydraulic circuit 202 includes an actuator 240 of an alternative embodiment that performs work, and a prime mover 210 of an alternative embodiment that generates an oscillating flow of hydraulic fluid and controls the flow of hydraulic fluid to the actuator 240. The hydraulic circuit 202 also includes a recovery device 80 arranged in the hydraulic circuit 202 between the prime mover 210 and the actuator 240. The recovery device 80 allows the oscillating hydraulic system 201 to avoid hydraulic locking and capture reduced pressure energy for subsequent use of the hydraulic system 201.

[0078] The prime mover 210 includes a variable speed one-way pump 212 driven by a constant speed electric motor 211. The electric motor 211 controls the direction of the pump 212. The pump 212 includes a pump a port 212a, which is connected to the prime mover a port 213 and the a port 243 of the actuator 240 via the first fluid line 203 of the hydraulic circuit 202. In addition, the pump 212 includes a pump B port 212B connected to the prime mover B port 214 and the B port 244 of the actuator 240 via a second fluid line 204. Pump B port 212B is connected to reservoir 224, and pump 212 directs hydraulic fluid from pump a port 212a to prime mover a port 213 via check valve 218 and filter 221.

[0079] The prime mover 210 includes a pressure relief device 225 connected to the first and second fluid lines 203, 204 and therefore to the pump 212. The pressure relief device 225 includes an adjustable pressure relief valve 219 configured to prevent damage to circuit components due to overpressure of the hydraulic circuit 202.

[0080] The prime mover 210 may also include a constant pressure source (not shown), such as a main accumulator or a charging pump.

[0081] The prime mover 210 includes a control valve 229 connected in parallel with the pressure relief device 219 to the first and second fluid lines 203, 204. The control valve 229 is connected to the first and second fluid lines 203, 204 at a position between the pressure relief device 229 and the prime mover A and B ports 213, 214. Control valve 229 is a three position, double solenoid control valve. The control valve 229 includes a first position 229 (1), a second position 229 (2), and a third position 229 (3). In the first position 229 (1), hydraulic fluid from pump a port 212a via fluid line 203 is directed to actuator B port 244 via prime mover B port 214, and hydraulic fluid from actuator a port 243 via prime mover a port 213 is directed to pump B port 212B. In the second position 229 (2), the control valve closes all ports and no fluid flows between the pump 212 and the A and B ports of the prime mover 210. In the third position 229 (3), hydraulic fluid from pump a port 212a via fluid line 203 is directed to actuator a port 243 via prime mover a port 213, and hydraulic fluid from actuator B port 244 via prime mover B port 214 is directed to pump B port 212B.

[0082] The actuator 240 is a rotary actuator, such as but not limited to a single blade or double blade rotary actuator. In the case of a single blade rotary actuator, the actuator 240 may include a housing 242 and a blade 245 disposed in the housing 242. The blade 245 forms a seal with the housing 245 and separates the internal space of the housing 242 into a first chamber 254 including the actuator a port 243 and a second chamber 255 including the actuator B port 244. The actuator 240 includes a rod 248 connected to the blade 245 and projecting from the housing 245. Due to the unequal pressure between the first chamber 254 and the second chamber 255, the movement of the blade 245 in the housing causes the rotation of the rod 248. The oscillation of the hydraulic fluid between the first chamber 254 and the second chamber 255 causes an oscillating rotational movement of the rod 248. Therefore, the actuator 240 is a rotary actuator configured to provide oscillating motion between rotation in the first direction and rotation in the second direction opposite to the first direction.

[0083]The recovery device 80 is provided in the hydraulic circuit 202 between the prime mover 210 and the actuator 240. In particular, the first recovery module 81 is connected to the first fluid line 203 via the first branch line 5. The first branch line 5 is connected to the first fluid line 203 at a position between the prime mover a port 213 and the actuator a port 243. The second recovery module 88 is connected to the second fluid line 204 via the second branch line 6. The second branch line 6 is connected to the second fluid line 204 at a position between the prime mover B port 214 and the actuator B port 244.

[0084] Therefore, the recovery device 80 allows the volume on the side of the actuator 240 with the trapped hydraulic fluid volume to increase, thereby reducing its pressure to the nominal value and capturing a portion of the potential energy stored in the compressed fluid before reversal. In addition, the recovery device 80 also reduces the hydraulic shock associated with rapid decompression. At each reversal of the blade 245 in the housing 242, the hydraulic circuit pressure is first reduced by an additional compressed volume V corresponding to entering one of the first and second recovery modules 81 and 88 c Associated pressure attenuation.

[0085] reference resources Figure 4 , the hydraulic system 301 of another alternative embodiment includes a hydraulic circuit 302. The hydraulic circuit 302 includes an actuator 340 of an alternative embodiment that performs work, and a prime mover 310 of an alternative embodiment that generates an oscillating flow of hydraulic fluid and controls the flow of hydraulic fluid to the actuator 340. The hydraulic circuit 302 also includes a recovery device 80 arranged in the hydraulic circuit 302 between the prime mover 310 and the actuator 340. The recovery device 80 allows the oscillating hydraulic system 301 to avoid hydraulic locking and capture reduced pressure energy for subsequent use of the hydraulic system 301.

[0086] The prime mover 310 includes a constant speed one-way pump 312 driven by a constant speed electric motor 311. The electric motor 311 controls the speed of the pump 312. The pump 312 includes a pump a port 312A connected to the prime mover a port 313 and the a port 343 of the actuator 340 via the first fluid line 303 of the hydraulic circuit 302. In addition, the pump 312 includes a pump B port 312b connected to the prime mover B port 314 and the B port 344 of the actuator 340 via a second fluid line 304. Pump B port 312b is connected to reservoir 324, and pump 312 directs hydraulic fluid from pump a port 312A to prime mover a port 313 via check valve 318 and filter 321.

[0087] The prime mover 310 includes a pressure relief device 325 connected to the first and second fluid lines 303, 304 and therefore to the pump 312. The pressure relief device 325 includes an adjustable pressure relief valve 319 configured to prevent damage to circuit components due to overpressure of the hydraulic circuit 302.

[0088] The prime mover 310 includes a control valve 329 connected in parallel with the pressure relief device 325 to the first and second fluid lines 303, 304. The control valve 329 is connected to the first and second fluid lines 303, 304 at a position between the pressure relief device 329 and the prime mover A and B ports 313, 314. Control valve 329 is a three position, double solenoid control valve. The control valve 329 includes a first position 329 (1), a second position 329 (2), and a third position 329 (3). In the first position 329 (1), hydraulic fluid from pump a port 312A via fluid line 303 is directed to actuator B port 344 via prime mover B port 314, and hydraulic fluid from actuator a port 343 via prime mover a port 313 is directed to pump B port 312b. In the second position 329 (2), the control valve closes all ports and no fluid flows between the pump 312 and the A and B ports of the prime mover 310. In the third position 329 (3), hydraulic fluid from pump a port 312A via fluid line 303 is directed to actuator a port 343 via prime mover a port 313, and hydraulic fluid from actuator B port 344 via prime mover B port 314 is directed to pump B port 312b.

[0089] The actuator 340 is a differential area, single rod hydraulic cylinder 341, which includes a cylinder housing 342 and a piston 345 arranged in the cylinder housing 342. The piston 345 forms a seal with the cylinder housing 342 and separates the internal space of the cylinder housing 342 into a first chamber 354 including the actuator a port 343 and a second chamber 355 including the actuator B port 344. The cylinder 341 includes a rod 348 disposed in the second chamber 355. The first end 352 of the rod 348 is connected to the side of the piston 345 facing the second chamber 355, and the second end 353 of the rod 348 is configured to be connected to the load.

[0090] The speed of the actuator 340 is a function of the angular speed of the electric motor 311 and the displacement of the pump 312. The direction of actuator 340 is a function of control valve 329.

[0091] The actuator 340 is a linear actuator configured to provide oscillating motion between a forward stroke in a first direction (see arrow 56) and a retraction stroke in a second direction opposite to the first direction (see arrow 58). reference resources Figure 4 , the forward stroke corresponds to the movement of the piston 345 in the first direction 56 in the cylinder housing 342, for example, relative to Figure 4 The orientation shown in is from side a to side B. The retraction stroke corresponds to the movement of piston 345 in the second direction 58 in cylinder housing 342, for example, relative toFigure 4 The orientation shown in is from side B to side a. In addition, the actuator 340 is configured to be connected to the load in each of the forward stroke and the retraction stroke, and the movement is realized by the hydraulic fluid provided by the prime mover 310 via the first and second fluid lines 303, 304.

[0092] The recovery device 80 is provided in the hydraulic circuit 302 between the prime mover 310 and the actuator 340. In particular, the first recovery module 81 is connected to the first fluid line 303 via the first branch line 5. The first branch line 5 is connected to the first fluid line 303 at a position between the prime mover a port 313 and the actuator a port 343. The second recovery module 88 is connected to the second fluid line 304 via the second branch line 6. The second branch line 6 is connected to the second fluid line 304 at a position between the prime mover B port 314 and the actuator B port 344.

[0093] Therefore, the recovery device 80 allows the volume on the side of the actuator 340 with the trapped hydraulic fluid volume to increase, thereby reducing its pressure to the nominal value and capturing a portion of the potential energy stored in the compressed fluid before reversal. In addition, the recovery device 80 also reduces the hydraulic shock associated with rapid decompression. Each time the piston 345 reverses in the cylinder housing 342, the hydraulic circuit pressure first decreases through the additional compression volume V corresponding to one of the first and second recovery modules 81 and 88 c Associated pressure attenuation.

[0094] reference resources Figure 5 , the hydraulic system 401 of another alternative embodiment includes a hydraulic circuit 402. The hydraulic circuit 402 includes an actuator 440 that performs an alternative embodiment of the work, and a prime mover 410 that generates an oscillating flow of hydraulic fluid and controls the flow of hydraulic fluid to the alternative embodiment of the actuator 440. The hydraulic circuit 402 also includes a recovery device 80 arranged in the hydraulic circuit 402 between the prime mover 410 and the actuator 440. The recovery device 80 allows the oscillating hydraulic system 401 to avoid hydraulic locking and capture reduced pressure energy for subsequent use of the hydraulic system 401.

[0095] The prime mover 410 includes a first pump 412 and a second pump 432. The first and second pumps 412 and 432 are constant speed two-way pumps respectively, and each is driven by a common constant speed first electric motor 411. For example, both the first pump 412 and the second pump 432 may be connected to the output shaft of the electric motor 411. The electric motor 411 controls the speed and direction of the first pump 412 and the second pump 432.

[0096] The first pump 412 includes a pump a port 412a, which is connected to the prime mover a port 413 and the a port 443 of the actuator 440 via the first fluid line 403 of the hydraulic circuit 402. In addition, the first pump 412 includes a pump B port 412b connected to the first reservoir 424.

[0097] The second pump 432 includes a pump a port 432A connected to the second reservoir 434 and a pump B port 432B connected to the prime mover B port 414 and the B port 444 of the actuator 440 via the second fluid line 404.

[0098] The prime mover 410 includes a filling pump 426 driven by a variable speed second electric motor 431. The filling pump 426 is a constant speed one-way pump. The filling pump 426 includes a pump a port 426A connected to the first and second fluid lines 403, 404 via corresponding check valves 416, 417. The second motor 431 controls the speed of the filling pump 426 and the synthetic flow from the filling pump 426 via the pump a port 426A. In addition, the filling pump 426 includes a pump B port 426B connected to the third reservoir 435.

[0099] In some embodiments, the first, second and third memories 424, 434 and 435 are separated from each other, while in other embodiments, the first, second and third memories 424, 434 and 435 are a single common memory.

[0100] In some embodiments, the prime mover 410 may also include a pressure relief device (not shown), a filter (not shown), and / or other auxiliary components that contribute to the efficient operation of the prime mover 410.

[0101] The actuator 440 includes a pair of hydraulic cylinders 441 and 461 connected in parallel. Specifically, the actuator 440 includes a differential area single rod first hydraulic cylinder 441 and a differential area single rod second hydraulic cylinder 461.

[0102] The first cylinder 441 includes a first cylinder housing 442 and a first piston 445 arranged in the first cylinder housing 442. The first piston 445 forms a seal with the first cylinder housing 442 and separates the internal space of the first cylinder housing 442 into a first chamber 454 connected to the actuator a port 443 and a second chamber 455 connected to the actuator B port 444. The first cylinder 441 includes a first rod 448 disposed in the second chamber 455. The first end 449 of the first rod 448 is connected to the side of the first piston 445 facing the second chamber 455, and the second end 450 of the first rod 448 is configured to be connected to the load.

[0103]The second cylinder 461 includes a second cylinder housing 462 and a second piston 465 arranged in the second cylinder housing 462. The second piston 465 forms a seal with the second cylinder housing 462 and separates the internal space of the second cylinder housing 362 into a third chamber 474 connected to the actuator a port 443 via the third fluid line 408 and a fourth chamber 475 connected to the actuator B port 444 via the fourth fluid line 409. The second cylinder 461 includes a second rod 471 disposed in the third chamber 474. The first end 472 of the second rod 471 is connected to the side of the second piston 265 facing the third chamber 474, and the second end 473 of the second rod 471 is configured to be connected to the load.

[0104] The recovery device 80 is provided in the hydraulic circuit 402 between the prime mover 410 and the actuator 440. In particular, the first recovery module 81 is connected to the first fluid line 403 via the first branch line 5. The first branch line 5 is connected to the first fluid line 403 at a position between the prime mover a port 313 and the actuator a port 343. The second recovery module 88 is connected to the second fluid line 404 via the second branch line 6. The second branch line 6 is connected to the second fluid line 404 at a position between the prime mover B port 414 and the actuator B port 444.

[0105] Therefore, the recovery device 80 allows the volume on the side of the actuator 440 with the trapped hydraulic fluid volume to increase, thereby reducing its pressure to the nominal value and capturing a portion of the potential energy stored in the compressed fluid before reversal. In addition, the recovery device 80 also reduces the hydraulic shock associated with rapid decompression. During each reversal of the pistons 445 and 465 in the corresponding cylinder housings 442 and 462, the hydraulic circuit pressure first decreases through the additional compression volume V corresponding to one of the first and second recovery modules 81 and 88 c Associated pressure attenuation.

[0106] reference resources Figure 6 , the hydraulic system 501 of another alternative embodiment includes a hydraulic circuit 502. The hydraulic circuit 502 includes the above description Figure 1 The actuator 40 and the prime mover 10. The hydraulic circuit 502 also includes a recovery device 580 of an alternative embodiment provided in the hydraulic circuit 502 between the prime mover 10 and the actuator 40. be similar to Figure 1 Recovery device 80, Figure 6 The recovery device 580 is configured to capture and store hydraulic fluid displaced from the actuator 40 during operation of the prime mover 10. In particular, the recovery device 580 is configured to capture and store the fluid V displaced from the actuator 40 during the transition between the forward stroke and the retraction stroke of the actuator 40 c Excessive hydraulic fluid caused by compression. However, Figure 6 The recovery device 580 has a ratio of Figure 1 The recovery device 80 shown in has fewer components because the recovery device 580 includes a single common accumulator 581, as will now be described in detail.

[0107] The recovery device 580 includes a recovery module 581, which includes a recovery accumulator 582. The recovery actuator 582 is connected to the first fluid line 3 via the first branch line 505 and to the second fluid line 4 via the second branch line 506. In particular, the recovery accumulator 582 is provided at the ends of the first and second branch lines 505, 506. The first branch line 505 is connected to the first fluid line 3 at a position between the prime mover a port 13 and the actuator a port 43. The second branch line 506 is connected to the second fluid line 4 at a position between the prime mover B port 14 and the actuator B port 44. The recovery device 580 includes a first control valve 583 arranged in the first branch line 505 between the recovery accumulator 582 and the first fluid line 3. The recovery device 580 includes a second control valve 590 arranged in the second branch line 506 between the recovery accumulator 582 and the second fluid line 4.

[0108] In the hydraulic circuit 502 including the recovery device 580, as the actuator 40 advances, the pump 12 supplies fluid to the actuator 40 via the prime mover a port 13 and the actuator a port 43, thereby driving the piston 45 from the a side to the B side in the cylinder housing 42. As the piston 45 advances, the first control valve 583 closes, the second control valve 590 opens, and the pressure gradually increases in the first fluid line 3 between the prime mover a port 13 and the actuator a port 43.

[0109] As the actuator 40 advances, the additional compressed volume V associated with the first chamber 54 c This increases the pressure P above the minimum pressure in the consumption recovery accumulator 582 min Any volume of. Once the recovery accumulator 582 reaches the minimum pressure P min , any volume required in the first chamber 54 that cannot be obtained from the second chamber 55 will be supplied by the charging pump 30 pumped from the accumulator 15. The second control valve 590 can reach the minimum pressure P at the recovery accumulator 582 min Then, and before the motion is reversed.

[0110] After the forward movement stops, but before reversing, the first control valve 583 is opened, allowing hydraulic fluid to flow from the first chamber 54 into the recovery accumulator 582. This flow will consume additional volume v c To reduce the pressure in the first chamber 54 to close to the minimum pressure P min。 When the first chamber 54 of cylinder 41 is depressurized, pump 12 is temporarily suspended. When the pressure of the first fluid line 3 stabilizes to the desired nominal value, the actuator 40 can be reversed due to the higher force generated in the second chamber 55 of the cylinder 41.

[0111] In the hydraulic circuit 502 including the recovery device 580, as the actuator 40 retracts, the pump 12 supplies fluid to the actuator 40 via the prime mover B port 14 and the actuator B port 44, thereby driving the piston 45 from the B side to the a side in the cylinder housing 42. As the piston 45 retracts, the second control valve 590 closes, the first control valve 583 opens, and the pressure gradually increases in the second fluid line 4 between the prime mover B port 13 and the actuator B port 44.

[0112] As the actuator 40 retracts, the additional compressed volume V associated with the second chamber 55 c This increases the pressure P above the minimum pressure in the consumption recovery accumulator 582 min Any volume of. Once the recovery accumulator 582 reaches the minimum pressure P min , any volume required in the second chamber 55 that cannot be obtained from the first chamber 54 will be supplied by the charging pump 30 pumped from the main accumulator 15. The first control valve 583 reaches the minimum pressure P at the recovery accumulator 582 min Then, and before the motion is reversed.

[0113] After the retraction movement stops, but before reversing, the second control valve 590 is opened, allowing hydraulic fluid to flow from the second chamber 55 into the recovery accumulator 582. This flow will consume additional volume v c Part of. When the second chamber 55 of cylinder 41 is depressurized, pump 12 is temporarily suspended. When the pressure of the second fluid line 4 stabilizes to the desired nominal value, the actuator 40 can be reversed due to the higher force generated in the first chamber 54 of the cylinder 41.

[0114] The subsequent movement of piston 45, both forward and retraction, will follow the pattern outlined in the above section.

[0115] Therefore, the recovery device 580 allows the volume on the side of the actuator 40 with the trapped hydraulic fluid volume to increase, thereby reducing its pressure to the nominal value and capturing a portion of the potential energy stored in the compressed fluid before reversal. In addition, the recovery device 580 also reduces the hydraulic shock associated with rapid decompression. In addition, the recovery device 580 avoids the sudden loss of fluid from the main circuit and stabilizes the minimum pressure P min Control of the device. At each reversal of the piston 45 in the cylinder housing 42, the hydraulic circuit pressure first decreases through the additional compressed volume V in the recovery accumulator 582 entering the recovery device 580 c Associated pressure attenuation.

[0116] Although the recovery device 580 is illustrated herein as including Figure 1 The hydraulic circuit of the prime mover 10 and the actuator 40 is used, but the recovery device 580 is not limited to Figure 1 The prime mover 10 is used with the actuator 40. It should be understood that other prime movers and actuators can be replaced Figure 1 The prime mover 10 and actuator 40 shown in, including but not limited to the above prime movers 200, 300, 400 and actuators 240, 340, 440, as long as the resulting hydraulic system generates an oscillating motion and is configured to be connected to the load in both directions of the oscillating motion.

[0117] This embodiment can also be used in the variant described, which reverses the functions of the first and second control valves 583 and 590 and is close to the higher pressure P s Operate the recovery accumulator 582 at a pressure of.

[0118] A selective illustrative embodiment of a hydraulic circuit including a recovery device is described in some detail above. It should be understood that this paper describes only the structures considered necessary to clarify the hydraulic circuit. Other conventional structures and conventional structures of auxiliary and auxiliary components of the hydraulic circuit including the recovery device are assumed to be known and understood by those skilled in the art. In addition, although the working example of the hydraulic circuit including the recovery device is described above, the hydraulic circuit and the recovery device are not limited to the above working example, but various design changes can be made without departing from the hydraulic circuit as claimed in the claim.