JPS60208610A - Power regenerating hydraulic circuit of hydraulic cylinder - Google Patents

Abstract

PURPOSE:To save energy by regenerating positional energy of hydraulic cylinder oil which is generated after the hydraulic cylinder is operated upwards, as a driving source for another actuator during the lowering process. CONSTITUTION:A main pipe passage which is connected to a boom hydraulic cylinder 5 is connected to the main pipe passage of a shift hydraulic cylinder 7 and a turning motor 8 via a branch circuit 32 including a check valve. As a result, when the boom hydraulic cylinder 5 is shifted into a lowering process from the high limit, a valve 12 is controlled so as to communicate the bottom end of the boom hydraulic cylinder 5 with the rod end thereof, then a pressure at the pump port 15 of the valve device 12 is increased. Since the pressure may be used as the driving sources for the shift hydraulic cylinder 7 and the turning motor 8, energy saving can be effected.

Description

[Detailed Description of the Invention] [Technical Field to which the Invention Pertains] This invention relates to a lifting device using a hydraulic cylinder, and in particular to an apparatus for effectively distributing the potential energy of oil possessed by a hydraulic cylinder to other actuators after a lifting operation. This invention relates to hydraulic pressure/linda power regeneration hydraulic circuit.

[Prior art and its problems]

2. Description of the Related Art Conventionally, a lifting device shown in FIG. 1 has been known for lifting and lowering a heavy object using a hydraulic cylinder and a swing motor. The basic configuration of FIG. 1 will be explained. A main shaft 2 extending perpendicularly to the base l and a lower table 3 fitted into the main shaft 2.
A boom hydraulic cylinder (hereinafter simply referred to as boom cylinder) 5 that engages with the upper table 4 and enables the upper table 4 to move up and down, and a shift table 6 provided at one end of the upper table 4 that extends and retracts. It consists of a shift hydraulic cylinder (hereinafter simply referred to as a shift cylinder) 7 and a swing motor 8 that integrally rotates the lower table 3 and the upper table 4 and stops them at a predetermined position.

The operating means in this basic configuration has a circuit configuration as shown in FIG. 2. In FIG. 1.1 neutral hydraulic pump (hereinafter simply referred to as pump) PI, P2. P'3, and the control valves 9, 10.11 are operated by operating means (hereinafter simply referred to as regulators) 9a, 9b, 10a, 10b.

When operating at 11a and 10b, pump PI, P2゜P3
Configured to connect to.

Next, the operation of this circuit configuration will be explained. In the case of sequence operation of raising-turn-shifting in the upper and lower tables 4, 3 and the shift table 6, first, the regulator 9b of the control valve 9 is energized to supply oil from the pump P1 to the bottom side of the poop cylinder 5, and the rod The oil on the side is returned to the tank T via the center bypass passage, and the upper table 4 is raised by the extension action of the piston 5a of the boom cylinder 5.

At the upper limit of the upper table 4, the regulators lla and llb of the control valve 11 are energized, the oil from the pump P3 is supplied to the swing motor 8, and the oil is returned to the tank T via the center bypass passage, and the oil is returned to the tank T via the center bypass passage. is driven, and when the upper table 4 and the lower table 3 have been rotated to a predetermined position, the regulator (111) is cut off and the upper and lower tables 4.3 are stopped at the predetermined positions. Next, the regulator 10a' of the control valve 10 is energized, the oil from the pump P2 is supplied to the bottom side of the shift cylinder 7, and the oil on the rod side is returned to the bottom side T. The piston 7a of the shift cylinder 7 is extended and the shift table 6 is emitted. move in the direction. Through such an operation, the heavy object W rises, turns, and moves from the A position to the fiB position as shown in FIG.

Contrary to the above, in the case of a shift->turn-down sequence operation, the regulator 10b of the control valve 7 is energized, the oil from the pump P2 is supplied to the rod side of the shift cylinder 7, and the discharged oil is returned to the tank. The piston 7a is retracted and the shift table 6 is returned to its original position. Next, the operation for rotating the upper and lower tables 4 and 3 is controlled by the regulator l of the control valve 11.
When lb or lla is excited, it is driven in the opposite direction to the above-mentioned upward movement and returns to its original position. Next, the regulator 9a of the control valve 9 is energized, oil from the pump Pl is supplied to the rod side, and oil from the bottom side is returned to the tank T, and the upper table 4 is lowered by the contraction of the piston 5a of the boom cylinder 5. This operation causes the heavy object W to return from the B position to the A position.

In the sequence operation described above, each control valve 9, 10, 11 is controlled by the order determined by the controller and the ON/OFF of an electric signal by a limit switch (not shown) provided at the travel limit of each actuator. The speed of the actuator is controlled by the flow rate of the opening of the control valve stroke in accordance with the amount of excitation of the regulator of each control valve based on the predetermined strength or weakness of the electric signal.

In this conventional circuit, each pump PL, P2 . P3 is control valve 9, 10.1
The entire discharge amount is unloaded through the center bypass path in the neutral state of No. 1, and the discharge amount of each pump Pl, pz, and p3 during operation is a predetermined flow rate that is supplied to each actuator via the control valves 9, 10, and 11. A portion of the waste is squeezed out through the center bypass. Therefore, when the control valve is in the neutral state, energy loss occurs due to unloading on the discharge side due to pipe pressure, and when the control valve is in operation, the boom maintains its position regardless of the ascending and descending processes. The cylinder uses a large diameter, and a portion of this cylinder is squeezed into the tank, resulting in energy loss, as well as a huge amount of hydraulic energy accumulated in the ring when descending.
Potential energy) is released into the tank via the control valve 9, which is unfavorable for obtaining the effectiveness of the oil.

[Purpose of the invention]

The purpose of this invention is to recover and effectively distribute and use the potential energy of the oil in the rising hydraulic cylinder after the lift is activated in a lifting device using a hydraulic cylinder and a swing motor as a driving source for the actuator of the descending process. The object of the present invention is to provide a power regeneration hydraulic circuit for a hydraulic cylinder that measures energy and enables different combined operations depending on the energy distribution method.

[Summary of the invention]

This invention comprises a lower table that is inserted into a main shaft erected on a base, a boom hydraulic cylinder that engages with the upper table and enables the upper table to move up and down, and one end of the upper table that is moved up and down by which hydraulic cylinder. A shift hydraulic cylinder that allows a shift table provided in an extension part to be extendable and retractable; and a swing motor that integrally rotates the lower and upper tables along the base and stops them at a predetermined position; In a hydraulic circuit of an elevating device configured to supply pressure oil from each hydraulic pump to a hydraulic cylinder and a swing motor via each control valve controlled by operation of an operating means, a pump and a boom connected to the hydraulic pump are provided. A boom valve device that connects respective supply and discharge ports connected to the supply side and discharge side of a hydraulic cylinder via a valve member, and connects these supply and discharge ports and a tank tank via a valve member, and this boom valve device A correction device that detects the supply side pressure of the hydraulic cylinder through the valve member and the discharge side pressure of the hydraulic pump with a pressure sensor, and processes and corrects both positive forces to a constant value, and the constant pressure of this correction device is introduced. a regulator for controlling the discharge amount of the hydraulic pump; a shift valve device and a swing motor valve device having at least equivalent configurations with respect to the boom valve device and the actuator; a boom valve of the boom valve device and a boom valve of the other valve device; and are connected in parallel via a branch circuit.

Furthermore, in the power regeneration hydraulic circuit of the hydraulic cylinder, an operating means for controlling the valve member of each valve device (-2 and 7-
It is characterized by the use of cans.

Furthermore, when the predetermined valve portion of the above-mentioned valve device is simultaneously operated, the discharge side valve member of the valve device changes the pressure of the pump to the supply side pressure of the shift cylinder. and a configuration in which the supply side pressure of the swing motor is higher than the higher pressure,
With these, the desired objective can be achieved.

Next, FIG. 3 showing an embodiment of the present invention will be described.

Note that the same members as in FIGS. 1 and 2 are designated by the same reference numerals, and detailed description thereof will be omitted. 12゜1: 3.14 is a boom valve device, a shift valve device, and a swing motor valve device, which correspond to the boom, shift, and swing control valves shown in FIG. Valve member 17
a, 17b, and supply/discharge ports 16a, 15b.
and the tank valve 18 connected to the tank T with the valve member 17C,
171). Valve members 17a, 17b, 17C, 17d of the boom valve device 12
1 is a valve that is opened and closed by an operating means (hereinafter simply referred to as a regulator), and its structure is well known, so a description thereof will be omitted. The valve member is energized and opened/closed by an electric signal sent from a controller to a regulator, and its opening amount is controlled by the strength of the signal, and is closed when not energized.

A correction device 19 detects the supply/discharge pressure of the boom cylinder 5 via the valve members 17a, 17b of the boom valve device 12 and the discharge pressure of the pump P1 with a pressure sensor, compares these side pressures, and performs constant processing correction. This correction device 19
The regulator 20, which is excited by introducing a constant pressure, increases or decreases the discharge amount of the pump P1 depending on the amount of excitation. The shift valve device 13 and the swing motor valve device 14 have the same structure with respect to the members constituting the boom valve device 12, their installation locations, the shift cylinder 7, and the swing motor 8, and detailed explanations will be omitted. .

First, the shift valve device 13 is connected to the supply/discharge port 22 which connects the bomb pro 21 to the bottom side and rod side of the shift cylinder 7.
a, 22b and check valve, valve member 23a, 2
'3 b, and the supply/discharge ports 22a, 2
2b and the tank counter 24 are connected via a valve member 23C123d. 25 is a correction device and valve members 23a and 23b.
The supply and discharge pressure of the shift cylinder 7 and the discharge pressure of the pump P2 are detected by a pressure sensor, and the side pressures are compared and corrected.

A regulator 26 introduces a constant pressure from the correction device 25 to control the discharge amount of the pump P2. The swing motor valve device 14 also connects the pump 27 and the supply/discharge ports 28a and 28b connected to the supply side and the discharge side of the swing motor 8 with a check valve and a valve member 29a.

29b, and its supply/discharge port 28a.

28b and the tank counter 30 are connected via valve members 29C and 29d. A correction device 30 is provided which detects the supply and discharge pressure of the swing motor 8 via the valve members 29a and 29b and the discharge pressure of the pump P3 with a pressure sensor, compares these side pressures, and performs processing correction to a constant value. , this correction device 19
The regulator 31, which is excited by introducing a constant pressure, increases or decreases the discharge amount of the pump P3 depending on the amount of excitation.

The upstream side of the boom valve device 15 of the boom valve device 12, the boom device 21 of the shift valve device 13, and the swing motor valve device 14
It is connected to the bomb pro 27 via a branch circuit 32 having a check valve. Each valve member of each valve device 12, 13, 14 which has been cut is appropriately controlled using sequence operation as a method of introducing the valve member into its regulator. Further, valve devices 12 and 13 for each of the boom, shift and swing motors 8
, 14 predetermined valve members are operated simultaneously, the discharge side valve member 17d of the boom valve device 12 increases the pressure of the bomb pro 15 higher than the supply side pressure of the shift cylinder 7 and the supply side pressure of the swing motor 8. It is configured to do this.

Next, the operation of the present invention will be explained. First, the sequence operation according to the ascending process of ascending, turning, and shifting will be explained.

In the operation of extension of the boom cylinder 5, the regulator 20 of the pump P1 and the valve member 17b of the boom valve device 12
, 17c, when an electric signal from the controller is inputted to the regulators, the pump P1 starts discharging oil due to the excitation of these regulators, and the valve members 17b and 17c open. Therefore, the discharge oil of pump Pl is Bonpro 15,
Oil is supplied to the bottom side of the boom cylinder 5 via the opening of the valve member 17 and the supply/discharge port 16b, and oil on the rod side is discharged to the tank T via the supply/discharge port 16a, the opening of the valve member 16C, and the tank tank 18. do. This oil supply/discharge action causes the piston 5a of the boom cylinder 5 to extend upward, and in response, the upper table 4 rises to a predetermined position. Accordingly, the extension speed of the boom cylinder piston 5a is determined by the flow rate of oil flowing to the bomb pro 15 and the supply/discharge port 16b, but the discharge amount of the pump P1 that passes oil to the predetermined opening of the valve member 17b is Supply/discharge port 16b leading to the bottom side
The pressure on this side is detected at the discharge pressure side of the pump P1, and the value of this side pressure is processed and corrected to a constant value by the correction device 19, and this is carried out by the control of the regulator 2o which introduces the output of this correction pressure signal. Therefore, the flow rate passing through the predetermined opening degree of the valve member 17b is not affected by the pressure applied to the bottom side of the boom cylinder 5, and is always limited to the flow rate generated by the pressure difference between the supply/discharge port 16b and the discharge pressure of the pump PI. Therefore, the flow rate can be controlled in accordance with the opening degree of the valve member 17. Valve member 1 that controls discharged oil on the rod side
If a large excitation signal is given to 7c in advance, the discharged oil can be returned to the tank T without resistance.

When the swing motor 8 is driven (in one direction), when an electric signal from the controller is input to the regulator 31 of the pump P3 and the regulators of the valve members 29b and 29c of the swing motor valve device 14, the pump P3 is energized by the excitation of these regulators. starts discharging valve members 29b, 2
9c opens.

Therefore, the oil discharged from pump P3 is
9I) and the swing motor 8 via the supply/discharge port 28b.
The discharged oil is sent to the supply side of the supply/discharge port 28d and the valve member 29.
The opening degree of C and the tank counter 30 are returned to the tank T, and the swing motor 8 is driven by this supply/discharge action. At this time,
As described in the control of the boom, the pressure of the supply/discharge port 28b leading to the supply side of the swing motor 8 and the discharge pressure of the pump P3 are detected by the pressure sensor, and the value of this dual-use force is detected by the correction device 30. Since the discharge amount of the pump P3 is controlled by the regulator 31 which receives the output of the corrected pressure signal after constant correction, the swing motor 8 is driven by the valve member 29.
A predetermined drive can be obtained with a flow rate commensurate with the opening degree of b, and the upper table 4 and lower table 3 are driven using the main shaft 2 as a fulcrum. Then, when a stationary electric signal is input to the regulators of the valve members 29C and 29b after turning to a predetermined position, the opening of the valve member 29c is gradually closed and the valve member 291) is fully opened, and the regulator 31 is controlled to maintain the discharge pressure. The discharge amount of the pump P3 is controlled to ensure a predetermined low pressure that does not become a load, and the swing motor 8 comes to rest when the valve member 29C is completely closed.

The shift cylinder 7 is extended by the valve member 23b.

Since the operation is the same as that of the boom cylinder 5 except that the piston 7a'f is extended in the horizontal direction by opening the 23C with excitation, the detailed operation will be omitted.

By the operation of the lifting step, the heavy object W can be moved upward from position A to position B as shown in FIGS. 1 and 2, but unlike the conventional cycle, each pump P1, P2, . P3 uses an electromagnetic proportional variable capacity type, so when it is in neutral, the discharge amount is zero, and when the operation is rising, it discharges the pressure and flow rate corresponding to each amount of work, so a part of the discharge amount is This eliminates the need to waste energy, thereby minimizing energy loss and achieving significant energy savings.

Next, the operation of the lowering step will be explained. First, in the above-mentioned lifting process, the boom actuating cylinder 5 is of a large diameter and has a large output in order to lift the heavy object, and at the upper limit, the potential energy is enormous, and this is It is a labor cost of energy to release it into the tank. Therefore, this huge potential energy is not only applied to the drive limit of the shift cylinder 7 and the swing motor 8 during the lowering process to effectively utilize the energy, but also pump P
2. The purpose is to save energy by putting P3 in an unloaded state, and the lowering process to achieve this energy saving will be explained.

1. At the upper limit when the series of operations of each table 3, 4 and 6 due to the extension of the boom cylinder 5 and the extension of the swing motor 8 and shift cylinder 7 is completed, the boom cylinder 5 is retracted to lower only the upper table 4. At this time, the valve member 17 of the valve device 12 is activated by an electric signal coming from the controller.
When the regulators a and 17b are energized and the valve member 17d is energized and opened at the same time, the piston 5a of the boom starts to retract. At this time, some of the oil discharged from the bottom side of the boom cylinder 5 is transferred to the valve member 17 from the supply/discharge port 16b.
b, the rod side is charged via the bomber 15 and the valve member 17a, and excess oil corresponding to the rod diameter of the boom cylinder 5 is returned to the tank T via the valve member 17d. Therefore, there is no need to charge the rod side of the boom cylinder 5 externally, and the discharged oil on the bottom side can be internally regenerated through the circuit, so the pump PL remains in the unloaded state and the rod side of the boom cylinder 5 The upper table 4 can be lowered gently without creating negative pressure on the sides.

In the neutral state of the boom cylinder 5, the pressure generated on the bottom side of the boom cylinder 5 by the external force W is given by the bottom cylinder diameter A, the pressure at the supply/discharge port 16I = &
In the circuit state where the valve members 17b and 172I are opened and the bottom side of the boom cylinder 5 and the rod side are connected, if the area a corresponds to the rod diameter, the supply/discharge port 1
6b pressure = 163 pressure = W/2 5. If the ratio of A to a is, for example, twice, the pressure at the supply/discharge port 16b = 2 x the pressure at the supply/discharge port 16b,
As a result, the pressure at the supply/discharge port 16'b = the pressure at the bomb processor 15 is increased. Therefore, by appropriately setting the ratio of A to a, the pressure of the bomber 15 can be made into a hydraulic pressure source sufficient to drive the shift no cylinder 5 and the swing motor 8 in terms of pressure. The speed when the boom is retracted and the pressure of the supply/discharge port 16b and the bomber 15 are controlled by the excitation opening of an electric signal to the valve member 17b.

Next, it will be described how the increased pressure of the boom pro 15 that occurs when the boom/cylinder 5 is retracted can be utilized for other actuators.

First, if we take as an example a sequence operation in which the shift cylinder piston 7a is actuated in the retracting direction at the same time as a signal for the lowering of the piston 5a of the boom/cylinder 5, and then the swing motor 8 is driven at a predetermined movement point, the boom valve device 12 valve members], 7a and 17b are energized and opened to open the valve member 15.
When the boom cylinder 5 contracts to increase the pressure of the boom cylinder 5, the valve members 23b and 23C of the foot valve device 13 are energized and opened at the same time as this contraction, and the rising pressure oil of the bomber 15 is passed through a branch circuit 32 having a check valve. Shift valve device 13
is supplied to the bomb pro 21. Therefore, the retraction operation of the piston 7a of the shift cylinder is performed by supplying and discharging the supply pressure oil through the valve member 23b and the discharge oil through the valve member 23c. When the piston 7a reaches a predetermined stroke contraction position, a signal from the limit switch causes the valve member 23b to close.

Since the opening of 23c is closed and the supply and discharge of pressure oil is cut off, the cylinder 7 completes its contraction operation. Next, when the valve members 29b and 29c of the swing motor valve device 14 are energized and opened, since the pressure oil of the pump 15 is already supplied to the pump 27, the pressure oil and the valve via the swing motor 81-1: the valve member 291) are It is driven in a predetermined direction by supplying and discharging the discharged oil through the member 29c. The turning motor 8 is stopped by the valve member 2.
9b.

This is done in the same manner as described above by closing 29C and cutting off the supply and discharge of pressure oil. Complete a series of sequence operations according to the order of success.

Here, the boom cylinder 50 regenerated oil is transferred to the shift cylinder 7.
When there is insufficient pressure to move and drive the swing motor 8 to a predetermined position, the pressure of each pump regulator 20, 26, 31 decreases.
By energizing and supplementing the insufficient oil in the regenerated oil with the oil discharged by this excitation, an appropriate operation can be obtained, and the sequence operation for moving the heavy object W from the 11th position to the A position in Fig. 1 can be performed. The shinai then retracts each cylinder and stops the swing motor 8, and the lowering process is completed without causing any trouble.

Next, when each actuator is operated in a four-way mode, which simultaneously retracts and drives the boom cylinder 5, shift cylinder 7, and swing motor 8, instead of the sequence operation described above, the valve members 17a, 17b of the boom valve device 12 and the shift valve are activated. Device 13
valve member 23b.

23c and the valve member 29c of the swing motor valve device 14,
29b is excited and opened at the same time, and the opening degrees of the valve members 23b and 29b on the supply side for shift and swing are appropriately set depending on the load on the shift cylinder 7 and the swing motor 8, the boom/cylinder 5 and the shift The cylinder 7 and the swing motor 8 can be operated in parallel by the action of regenerated oil generated when the piston 5a of the boom cylinder 5 contracts.

Furthermore, in the same way as above, when the speed control of the boom/cylinder 5 retraction/foot cylinder 7 retraction and the drive of the swing motor 8 is performed in parallel without being affected by the load (1) Similarly, the valve part U'17a, 1
7b and valve member 231), 23C and valve member 29c,
29b are energized and opened at the same time, the supply/discharge port 22. b and 2
81] is detected by a pressure sensor, and the boom valve device 12 is used to make the pressure of the bomb pro 15 slightly higher (10 α) than the pressure of the higher one (for example, the supply/discharge port 22b or 2F31). The excitation opening of the valve member 17d is controlled. If we assume that the pressure on the supply side (supply/discharge port 28b) of the swing motor 8 is higher than the pressure on the supply side (supply/discharge port 22b) of the shift cylinder 7, the pressure of the Bonpro 15 will be equal to the pressure of the soft Bonpro 21 and the rotation Supply/discharge port 2' on the supply side of the motor 8
8b is necessarily equal to the additional pressure added to the pressure, and therefore, the rotation motor 8 is driven by the supply/discharge port 28tl.
This is performed by introducing a flow rate that causes a pressure difference depending on the opening degree of the valve member 29b. On the other hand, in the shift valve device 12, the pressure of the bomber 21 is connected to the supply/discharge port 28I of the swing motor 8).
Therefore, a pressure difference is generated between the rod side supply and discharge port 22b of the shift cylinder 7, but at this time, an arithmetic device (not shown) detects the differential pressure across the valve member 23b and its opening flow rate, and The calculation is performed to excite and control the opening degree of the valve portion U' 2 :31) to a predetermined value.

This causes the boom cylinder 7 to operate with the desired supply oil. Therefore, when the boom cylinder 5 is lowered, the shift cylinder 7 and the swing motor 8 can be operated in parallel at a desired speed without being affected by the load.

〔Effect of the invention〕

As described above, according to the present invention, when a lifting device using a hydraulic cylinder and a swing motor moves from its upper limit to a lowering step, the bottom side of the boom hydraulic cylinder that enables vertical movement is communicated with the rod side. By opening the valve member of the valve device to increase the pressure in the valve device, the boosted oil can be used as an operating source for other shift cylinders and the swing motor, so energy activation can be increased. can. Furthermore, each actuator, which is charged with said pressurized oil by control of the valve member of each valve arrangement, allows sequential operation, parallel operation and speed control. This not only effectively distributes the entire amount of energy that the boom cylinder has at its upper limit to other shift cylinders and swing motors to regenerate energy, but also allows each hydraulic pump to be almost unloaded. This has the effect of saving energy by achieving significant power regeneration.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram showing a conventional lifting device, etc., and Figure 2 is a diagram showing the structure of a conventional lifting device.
FIG. 3 is a circuit diagram showing the moving and driving means constituted by the figure, and FIG. 3 is a circuit diagram showing the moving and driving means according to an embodiment of the present invention. 1...Base, 2...Main shaft, 3...Lower table, 4...
・Upper table, 5. Boom hydraulic cylinder, 6. Shift cylinder, 7. Shift hydraulic cylinder, 8. Swing motor, 9. Boom control valve, 10. Shift control valve,
11...Swivel motor control valve, Pi, P2. P3... Hydraulic pump, 12... Boom valve device, 13... Shift valve device, 14... Swivel motor valve device, 15, 21° 27.
・Bonpro, 16a, 16b・Boom valve device supply/discharge port%
22a, 22b... Supply/discharge port of shift valve device, 28a,
28b...Swivel motor supply/discharge port, 18, 24゜30 ・
=Tankuro of each valve device, 17a, 17b, 17C. 17d--Valve members of boom valve device, 23a, 23b, 2
3c, 23d・Valve members of shift valve device, 29a, 29b
. 29c, 29d... Valve member of swing motor valve device, 192
5.30... Correction device, 20, 26. 31... Regulator for each pump, 32... Branch circuit. Applicant: Toshiba Machine Co., Ltd.

Claims (1)

[Scope of Claims] l) A boom hydraulic cylinder that engages with a lower table and an upper table that are inserted into a main shaft erected on a base and allows the upper table to move up and down, and a boom hydraulic cylinder that allows the upper table to move up and down. A shift hydraulic cylinder provided at one end of the upper table extending part to make the shift table extendable and retractable, and a swing motor stored in the base to integrally rotate the lower and upper tables and stop them at a predetermined position, Said boom, 77
Hydraulic pump Pi is connected to each hydraulic cylinder and swing motor.
, P2. P2 pressure oil is operated by operating means 9;+,! jb, 10a
, Job, lla. Each control valve 9.111) is controlled by the operation of the control valve 9. IO, ]1
In the hydraulic circuit of the lifting device configured to supply water via the hydraulic pump PI, the pump PI connected to the hydraulic pump PI and the respective supply and discharge ports connected to the supply side and the discharge side of the boom hydraulic cylinder are connected via a valve member, and A boom valve device connects these supply/discharge ports and the tanker via a valve member, and a pressure sensor detects the pressure on the hydraulic cylinder supply side and the pressure on the discharge side of the hydraulic pump via the valve member of this boom valve device. , a correction device that processes and corrects this side pressure to a constant value, a regulator that controls the discharge amount of the hydraulic pump by introducing a constant pressure signal from the correction device, and the boom valve device.
A soft valve device and a swing motor valve device having at least the same configuration with respect to the actuator, and a boom valve device of the boom valve device and a boom device of the other valve device are connected to each other in a parallel manner by a branch circuit. 2) A power regeneration hydraulic circuit for a hydraulic cylinder according to claim 1, characterized in that a sequence is used as an operating means for controlling the valve members of each valve device. 3) When the predetermined valve members of each of the valve devices are operated simultaneously, the discharge side valve member of the boom valve device changes the pressure of the pump 15 to the supply side pressure of the shift hydraulic cylinder and the supply side pressure of the swing motor. A power regeneration hydraulic circuit for a hydraulic cylinder according to claim 1, wherein the pressure is higher than the higher pressure.