WO1998013603A1

WO1998013603A1 - Hydraulic oil recovery/reutilization system

Info

Publication number: WO1998013603A1
Application number: PCT/JP1997/003416
Authority: WO
Inventors: Hiroshi Endo; Nobumi Yoshida; Kazuhiro Maruta
Original assignee: Komatsu Ltd.
Priority date: 1996-09-25
Filing date: 1997-09-25
Publication date: 1998-04-02
Also published as: JP3362258B2

Abstract

The energy of a return hydraulic oil of an actuator is recovered and is reutilized as energy for operating other actuators. A first pump/motor (16) and a second pump/motor (17) are mechanically connected to form a pressure convertor (18), and a first circuit (22), to which the return hydraulic oil is supplied, is connected to the first pump/motor (16). An accumulator (27) is provided to a second circuit (25) connected to the second pump/motor (17). The first circuit (22) is connected to a discharge line of a main hydraulic pump (10) by a third circuit (29) and the pressure of a high pressure hydraulic oil is stored by the energy of the return hydraulic oil. The high pressure hydraulic oil is supplied to the discharge line (11) by the pressure of the high pressure hydraulic oil, and is reutilized.

Description

Description Pressurized oil recovery and reuse system

Technical field

The present invention relates to a construction machine such as a power shovel that stores high-pressure oil with the energy of return hydraulic oil from a hydraulic actuator and uses the stored high-pressure oil as an operating energy of the actuator. This is related to a pressure oil recovery and reuse system that is reused. Background art

As a power shovel, an upper revolving structure is provided on a lower vehicle body equipped with a traveling body so as to be pivotable with a hydraulic motor for pivoting, and a boom is attached to the upper revolving structure so as to be able to swing up and down with a boom cylinder. It is also known that an arm is attached to the boom by an arm cylinder so that the arm can swing up and down, and a bucket is attached to the arm by a bucket cylinder so that the arm can swing up and down.

The hydraulic motor for turning the power shovel, the cylinder for the boom, the cylinder for the arm, and the cylinder for the bucket are provided with the discharge hydraulic oil of the hydraulic pump in one chamber by switching the directional control valve. While supplying pressure oil from the other chamber to the tank.

For example, a boom directional control valve supplies hydraulic pressure from the hydraulic pump to the extension chamber of the boom cylinder and the pressure of the contraction chamber. The oil flows out to the tank and expands, supplying the pressure oil from the hydraulic pump to the compression chamber of the boom cylinder, and the hydraulic oil in the expansion chamber flows out to the tank and contracts. I have.

As described above, the return hydraulic oil for the turning hydraulic motor, the boom cylinder, the arm cylinder, and the bucket cylinder is returned to the tank because the pressure oil flows out to the tank. Energy of pressurized oil cannot be used.

For example, when the boom cylinder is contracted and operated, the self-weight of the boom, arm and bucket generates pressure in the return pressure oil from the extension chamber, but the return pressure The oil spills into the tank and the pressure (energy) cannot be reused. On the other hand, a device has been proposed that recovers and reuses the energy of the return pressure oil from the hydraulic factory. For example, a pressurized oil recovery and reuse system disclosed in Japanese Patent Publication No. 3-33922 is known.

As shown in Fig. 1, this pressure oil recovery and reuse system connects the chamber 2 of the single-acting cylinder 1, which is the factory, to the port 4 of the first pump / motor 3, as shown in Figure 1. Connect the port 6 of the second pump 5 which is mechanically connected to the first pump motor 3 to the hydraulic oil supply circuit 7, and connect the pressure oil supply circuit 7 to the check valve 8 by the check valve 8. The reservoir is connected to a hydraulic pressure source via a pressure reservoir 9.

In this system, the second pump motor 5 acts as a motor by supplying the pressure oil of the hydraulic source to the pressure oil supply circuit 7 to drive the first pump motor 3 and the first pump motor Overnight 3 power The pump acts to supply pressure oil to the chamber 2 of the single-acting cylinder 1 so that the single-acting cylinder 1 extends and operates.

When the supply of pressurized oil to the pressurized oil supply circuit 7 is stopped, the single-acting cylinder 1 contracts and operates with an external load, and pressure is generated in the return pressure oil in the chamber 2 to start the first pump motor 3. Drives and acts overnight. As a result, the second pump / motor 5 pumps and high-pressure oil is generated in the pressure oil supply circuit 7, and the high-pressure oil is blocked by the check valve 8, and the high-pressure oil is stored in the pressure reservoir 9. It is stored.

Then, when the pressure oil is supplied again to the pressure oil supply circuit 7 and the single-acting cylinder 1 is extended and operated, the high-pressure oil stored in the pressure accumulator 9 drives the second pump motor 5. Then, the first pump and the motor 3 act as a pump to supply high-pressure oil to the chamber 2 and reuse the pressurized oil (energy) stored in the accumulator 9.

The system described above stores high-pressure oil with the energy of the return pressure oil in chamber 2 of single-acting cylinder 1, and supplies the pressure oil to chamber 2 of single-acting cylinder 1 again with the stored high-pressure oil. Therefore, the stored high-pressure oil is only reused for the single-acting cylinder 1 and cannot be reused for other factories.

Therefore, an object of the present invention is to provide a hydraulic oil recovery and reuse system that can solve the above-mentioned problems.

Disclosure of the invention

The first invention relates to a first pump 'motor 16 and a second pump' motor 1 which are mechanically connected by the energy of the return pressure oil of the work which is operated by the pressure oil of the hydraulic power source. Consists of 7 A pressure oil recovery and reuse system characterized by operating a pressure transducer 18 to supply high-pressure oil to the hydraulic source.

According to the first invention, since the high-pressure oil is supplied to the hydraulic power source by the return pressure oil of the actuator, the return pressure oil recovered from the actuator is returned. Energy can be reused for other work overnight activities.

The second invention comprises a main hydraulic pump 10 for supplying pressure oil to the actuator, a first circuit 22 to which return pressure oil from the actuator is supplied, and the first circuit 22. The first pump 'motor 16' to which the circuit 22 is connected, and the variable capacity second pump which is mechanically connected to this first pump 'motor 16 and connected to the second circuit 25'. A third circuit 29 communicating the first circuit 22 with the discharge passage 11 of the main hydraulic pump 10; a pressure reservoir 27 provided in the second circuit 25; A pressure oil recovery and reuse system characterized by comprising a regeneration valve 30 that switches the third circuit 29 between a state in which pressure oil flow is allowed and a state in which pressure oil flow is blocked.

According to the second invention, the third circuit 29 is switched to the state in which the flow of the hydraulic oil is blocked by the regeneration valve 30, so that the first pump ′ and the motor 16 are driven by the return hydraulic oil. High pressure oil can be stored in the pressure accumulator 27 since the second pump-motor 17 operates as a pump.

By switching the third circuit 29 with the regeneration valve 30 to a state that allows the flow of pressurized oil, the second pump Since the first pump 17 and the first pump 16 operate to operate the pump, pressure oil is discharged to the first circuit 22 and the main hydraulic port is discharged via the third circuit 29. It is supplied to the discharge path 11 of the pump 10. As a result, the energy of the pressurized oil at the factory can be reused for the operation of other factories.

Also, when the second pump / motor 17 operates as a motor, the output torque of the second pump / motor 17 is increased or decreased by increasing or decreasing the capacity of the second pump / motor 17, that is, the first pump. 'Since the torque for driving the motor 16 changes, the pressure in the first circuit 22 is increased or decreased by the pump action of the first pump motor 16.

As a result, the pressure in the first circuit 22 is equal to or slightly higher than the pressure in the discharge passage 11 of the main hydraulic pump 10 and the pressure in the first circuit 22 is increased. It can be reused by supplying it to the 0 discharge path 11.

According to a third aspect of the present invention, a pressure accumulating valve 26 for communicating with and shutting off a second circuit 25 in the second aspect of the invention is provided, and a second pump mode is provided rather than the pressure accumulating valve 26 in the second circuit 25. This is a pressure oil recovery and reuse system that has a sequence valve 28 between the side of the evening 17 and the discharge path 11 of the main hydraulic pump 10.

According to the third aspect of the present invention, when the high-pressure oil has been stored in the pressure accumulator 27 and the second circuit 25 is shut off by the pressure accumulator valve 26, the high-pressure oil stored in the pressure accumulator 27 is discharged. Leakage can be prevented.

When the high-pressure oil is fully stored in the pressure accumulator 27, the high-pressure oil in the second circuit 25 is supplied from the sequence valve 28 to the main hydraulic pump 10. Since the pressure is supplied to the discharge path 11, the capacity of the pressure accumulator 27 can be reduced.

If the pressure-accumulation valve 26 is closed when the second pump / motor 17 is pumped and accumulates pressure, the high-pressure oil discharged from the second pump / motor 17 will be discharged from the sequence valve 28 From this, it is supplied directly to the discharge passage 11 of the main hydraulic pump 10.

As a result, the energy of the recovered pressurized oil can be reused immediately.

The fourth invention comprises a main hydraulic pump 10 for supplying pressure oil to the actuator, a first circuit 22 to which return pressure oil from the actuator is supplied, and a second circuit 22 for supplying the return pressure oil from the actuator. 1 A recovery valve 23 for switching the circuit 22 between a first state in which the pressurized oil flow is allowed and a second state in which the oil flow is blocked; a first pump / motor 16 connected to the first circuit 22; A pressure transducer 18 having a variable displacement second pump motor 17 mechanically connected to the first pump motor 16 and connected to the second circuit 25; and the first circuit. A third circuit 29 communicating the discharge passage 11 of the main hydraulic pump 10 with the second circuit 22, a pressure accumulator 27 provided in the second circuit 25, and a third circuit 29. A regeneration valve 30 for switching between a first state allowing flow and a second state preventing flow, a pressure accumulator valve 26 communicating with and shutting off the second circuit 25, and the second circuit The set pressure variable type set valve 2 provided between the second pump / motor 17 and the discharge path 11 of the main hydraulic pump 10 rather than the pressure storage valve 26 in 25 This is a system for collecting and reusing pressurized oil, characterized in that the system consists of 8 components. According to the fourth invention, after storing the high-pressure oil in the pressure accumulator 27, the recovery valve 23 is in the second state (closed), the pressure accumulating valve 26 is in the communicating state, and the regeneration valve 30 is in the second state. 1 (open) and the set pressure of the sequence valve 28 is set to a high pressure, so that the stored high-pressure oil passes from the third circuit 29 via the pressure transducer 18 to the main hydraulic pressure. It can be supplied to the discharge path 11 of the pump 10.

In addition, the collection valve 23 and the regeneration valve 30 are set to the second state (closed), the pressure accumulation valve 26 is set to the communication state, and the set pressure of the sequence valve 28 is set to a low pressure. Then, the stored high-pressure oil can be supplied to the discharge passage 11 of the main hydraulic pump 10 through the sequence valve 28.

Thus, the pressure transducer 18 can be driven by the high-pressure oil stored in the pressure accumulator 27 to supply low-pressure, large-flow pressure oil to the discharge path 11, and the pressure accumulator 27 The high-pressure oil stored in the tank can be supplied to the discharge passage 11 through the sequence valve 28.

When the actuator is operating, the collection valve 23 is set to the first state (open), the pressure accumulation valve 26 is set to the shut off state, the regeneration valve 30 is set to the second state (closed), and the sequence is set. By setting the set pressure of the valve 28 to a low pressure, the return pressure oil of the first circuit 22 can be supplied to the discharge path 11 via the pressure transducer 18 and the sequence valve 28. In addition, the collection valve 23 and the regeneration valve 30 are set to the first state (open), the storage valve 26 is set to the closed state, and the set pressure of the sequence valve 28 is set to high. Thus, the return pressure oil of the first circuit 22 can be supplied to the discharge path 11 through the third circuit 29.

With such a force, the return pressure oil from Akuchiyue overnight The pressure can be increased by the pressure transducer 18 without storing the pressure and supplied to the discharge path, and the return pressure oil can be efficiently supplied to the discharge path 11 via the third circuit 29 without storing the pressure.

According to a fifth aspect of the present invention, a first means for detecting a discharge pressure P 2 of the main hydraulic pump 10 and a second means for detecting a stored pressure P 1 of a pressure accumulator 27 of the second circuit 25 are provided. Means and the recovery valve 23, the pressure accumulation valve 26, and the regeneration valve 30 are switched based on the pressure detected by the first and second means, and the set pressure of the sequence valve 28 is changed. A third means, wherein when the differential pressure between the storage pressure P 1 and the discharge pressure P 2 is equal to or higher than a set differential pressure, the recovery valve 23 is set to the second state (closed); 26 is in the communicating state, the regeneration valve 30 is in the first state (open), the set pressure of the sequence valve 28 is high, and the differential pressure between the storage pressure P 1 and the discharge pressure P 2 is high. When the pressure difference is equal to or less than the set pressure difference, the collection valve 23 and the regeneration valve 30 are brought into the second state (closed), the pressure accumulation valve 26 is brought into the communicating state, and the set pressure of the sequence valve 28 is reduced The fourth aspect of the present invention is a pressure oil recovery and reuse system having a function of reducing pressure.

According to the fifth aspect, when the differential pressure between the storage pressure P 1 and the discharge pressure P 2 is equal to or higher than the set pressure difference, the recovery valve 23 is in the second state (closed), the storage valve 26 is in the communicating state, and the regeneration is performed. When the valve 30 is in the first state (open), the set pressure of the sequence valve 28 becomes high, and the stored high-pressure oil flows from the third circuit 29 through the pressure transducer 18. It is supplied to the discharge passage 11 of the main hydraulic pump 10.

When the differential pressure between the storage pressure P 1 and the discharge pressure P 2 is equal to or lower than the set pressure, the recovery valve 23 and the regeneration valve 30 are in the second state (closed), As the pressure valve 26 becomes in communication, the set pressure of the sequence valve 28 becomes low, and the stored high-pressure oil is discharged from the main hydraulic pump 10 through the sequence valve 28. Route 11 is supplied.

Therefore, the high-pressure oil stored according to the differential pressure between the storage pressure P1 and the discharge pressure P2 is supplied through the pressure transducer 18 or supplied through the sequence valve 28. If possible, the stored high-pressure oil can be efficiently supplied to the discharge passage 11 efficiently.

According to a sixth aspect of the present invention, there is provided a first means for detecting a discharge pressure P 2 of the main hydraulic pump 10, and a third means for detecting a pressure P 3 of the return pressure oil of the first circuit 22. The third means for switching the set pressure of the sequence valve 28 while switching the recovery valve 23, the pressure storage valve 26, and the regeneration valve 30 based on the pressure detected by the first and third means. The third means comprises: when the pressure P 3 is lower than the discharge pressure P 2, the recovery valve 23 is in the first state (open), the pressure accumulation valve 26 is shut off, and the regeneration valve 30 is In addition to the second state (closed), the set pressure of the sequence valve 28 is set to a low pressure, and when the pressure P 3 is higher than the discharge pressure P 2, the recovery valve 23 and the regeneration valve 30 are turned on. In the first state (open), it has a function to shut off the pressure accumulation valve 26 and set the set pressure of the sequence valve 28 to a high pressure. A hydraulic fluid recovery and reuse system of the fourth invention described.

According to the sixth invention, when the pressure P3 of the return pressure oil is lower than the discharge pressure P2, the recovery valve 23 is in the first state (open), the storage valve 26 is in the shut-off state, and the regeneration is performed. When the valve 30 is in the second state (closed), the set pressure of the sequence valve 28 becomes low, 1 Return of the circuit 2 2 Pressure oil is supplied to the discharge path 11 via the pressure transducer 18 and the sequence valve 28.

When the pressure P 3 of the return pressure oil is higher than the discharge pressure P 2, the recovery valve 23 and the regeneration valve 30 are in the first state (open), and the pressure accumulation valve 26 is in the shut off state. At the same time, the set pressure of the sequence valve 28 becomes high, so the return pressure oil of the first circuit 22 is supplied to the discharge path 11 through the third circuit 29.

Because of this, when the pressure of the return pressure oil is lower than the discharge pressure, the pressure converter 18 raises the pressure without storing the return pressure oil from the factory. And when the pressure of the return pressure oil is higher than the discharge pressure, the return pressure oil does not accumulate and is efficiently supplied to the discharge path 11 via the third circuit 29. it can. BRIEF DESCRIPTION OF THE FIGURES

The present invention will be better understood from the following detailed description and the accompanying drawings, which show embodiments of the invention.

The embodiments shown in the accompanying drawings are not intended to specify the present invention, but merely to facilitate explanation and understanding.

In the figure,

FIG. 1 is a conventional hydraulic circuit diagram.

FIG. 2 is a hydraulic circuit diagram showing the first embodiment of the present invention. FIG. 3 is a hydraulic circuit diagram showing a second embodiment of the present invention. FIG. 4 is a hydraulic circuit diagram showing a third embodiment of the present invention. Suitable bear for carrying out the invention

As shown in FIG. 2, the discharge path 11 of the main hydraulic pump 10 is provided with a first directional control valve 12 and a second directional control valve 13 so that the first actuator 14 and the second directional control valve 13 are provided. It is designed to supply pressurized oil to the factory 15th.

The pressure transducer 18 is obtained by mechanically connecting the first pump 'Money 16' and the second pump 'Money 17'. The first pump-motor 16 is a variable displacement type whose capacity changes by changing the inclination angle of the swash plate 19, and the second pump-motor 17 is the inclination angle of the swash plate 20. It is a variable capacity type in which the capacity changes by changing.

The main port 21 of the first pump / motor 16 is connected to a first circuit 22, which passes through a recovery valve 23 and a return port 1 of a first directional control valve 12. 2a, connected to the return port 13a of the second directional control valve 13 to be supplied with return pressure oil of the first actuator 14 and the second actuator 15.

The main port 24 of the second pump / motor 17 is connected to a second circuit 25.

The second circuit 25 is connected to a pressure accumulator 27 via a pressure accumulating valve 26 and to a discharge passage 11 of the main hydraulic pump 10 via a sequence valve 28.

The first circuit 22 is connected to a discharge path 11 of the main hydraulic pump 10 by a third circuit 29. The third circuit 29 is provided with a regeneration valve 30. The regeneration valve 30, the recovery valve 23, and the pressure storage valve 26 are closed by springs 30a, 23a, 26a. It is held in position a, and when it is energized to solenoids 30b, 23b, 26b, it becomes open position b.

A first pressure sensor 31 is provided in a discharge path 11 of the main hydraulic pump 10, and a second pressure sensor 32 is provided in a first circuit 22. The detection pressures of the first pressure sensor 31 and the second pressure sensor 32 are input to the controller 33. The controller 33 inputs the displacement control signal to the displacement control member 34 of the second pump motor 17 when the reuse signal is inputted, and detects the detected pressure of the first pressure sensor 31 1 The capacity of the second pump motor 17 is controlled so that the detected pressures of the second pressure sensor 32 become equal.

Next, the operation of collecting the return pressure oil and storing the pressure will be described.

The solenoid 23b of the recovery valve 23 is energized to the open position b, and the solenoid 26a of the accumulator 26 is energized to the open position b. In this state, when the first directional control valve 12 is set to the first position c and one of the chambers 14a of the first actuator 14 is supplied with pressurized oil and contracted, the other chamber 14 is operated. The return pressure oil in b flows into the first circuit 22 from the return port 12a. At this time, the regeneration valve 30 is in the closed position a.

The pressure oil that has flowed into the first circuit 22 flows into the main port 21 of the first pump / motor 16, and the first pump / motor 16 operates as a motor. Drive 7. At this time, the capacity of the second pump / motor 17 is reduced to discharge high-pressure oil when driven with the same drive torque.

This operation is performed by inputting a recovery signal to the controller 33. Alternatively, a small capacity signal may be output to the capacity control member 34 by the controller 33.

In addition, the solenoid 33 b of the collection valve 23 and the solenoid 26 b of the pressure accumulation valve 26 may be energized by the controller 33.

Thus, the second pump 17 operates as a pump to discharge high-pressure oil to the second circuit 25 and store the high-pressure oil in the pressure accumulator 27. At this time, when the high pressure oil is full in the pressure accumulator 27, the pressure of the second circuit 25 becomes higher than the set pressure of the sequence valve 28, and the high pressure oil of the second circuit 25 Is supplied to the discharge passage 11 of the main hydraulic pump 10.

During this operation, since the regeneration valve 30 is in the closed position a, the return pressure oil flowing into the first circuit 22 is higher than the pressure in the discharge path 11 and flows into the discharge path 11. If the pressure in the discharge path 11 is higher than the return pressure oil flowing into the first circuit 22, it does not flow into the first circuit 22.

When the collecting operation is completed, the pressure storing valve 26 is set to the closed position a so as to keep the high-pressure oil stored in the pressure storing device 27 from flowing out.

Next, the operation of reusing the stored high-pressure oil will be described.

When the energization of the solenoid 23 b of the recovery valve 23 is stopped and the closed position a is reached, the solenoids 26 b and 30 b of the pressure accumulating valve 26 and the regeneration valve 30 are both set. To the open position b. As a result, the high-pressure oil stored in the pressure accumulator 27 flows from the second circuit 25 into the main port 24 of the second pump 17 and the second pump / motor 17 The first bon Driving Poo Mo 1 6

The second pump motor 16 pumps and discharges high-pressure oil to the first circuit 22, and the high-pressure oil is supplied from the third circuit 29 to the discharge path 11 of the main hydraulic pump 10. You. At this time, the pressure of the second pump is set so that the pressure of the discharge passage 11 and the pressure of the first circuit 22 are equal (or the pressure of the first circuit 22 is slightly higher). Control the capacity of

Specifically, when the pressure of the first circuit 22 is lower than the pressure of the discharge path 11, a large displacement signal is output to the displacement control member 34 to increase the displacement of the second pump motor 17. By increasing the output torque of the second pump-motor 17 (the driving torque of the first pump * motor 16), the first pump-motor 16 can output high-pressure oil. To When the pressure of the first circuit 22 is higher than the pressure of the discharge path 11, the above procedure is reversed.

Since the first pump motor 16 is of a variable displacement type, even if the capacity of the second pump motor 17 is increased as described above, the pressure of the first circuit 22 is discharged. When the pressure is lower than the pressure of the channel 11, a small capacity signal is input from the controller 33 to the capacity control member 35, and the capacity of the first pump motor 16 is reduced to increase the pressure. Make it possible to discharge oil.

In other words, the first pump / motor 16 is of a variable displacement type in order to enlarge the pressure conversion area, and when the pressure conversion area is small, the first pump / motor 16 is of a fixed displacement type. It is good.

In addition, the pressure oil in the discharge path 11 is supplied from the third circuit 29 to the first circuit 2 A backflow prevention valve 36 may be provided in the third circuit 29 to surely prevent the backflow to 2.

Next, a description will be given of the operation of immediately recovering the energy of the recovered return pressure oil without storing it. By setting the recovery valve 23 to the open position b, and setting the regeneration valve 30 and the pressure storage valve 26 to the closed position a, the return pressure oil flowing into the first circuit 22 is compressed by the pressure transducer 18 As described above, the pressure is increased as described above, and is discharged to the second circuit 25. When the pressure becomes equal to or higher than the set pressure of the sequence valve 28, the pressure is directly supplied to the discharge path 11. If the regeneration valve 30 is set to the open position b in this state, the return pressure oil is supplied from the third circuit 29 to the discharge path 11.

Next, a second embodiment of the present invention will be described.

By providing a second check valve 37 on the output side of the sequence valve 28 as shown in Fig. 3, the backflow from the discharge passage 11 of the main hydraulic pump 10 to the second circuit 25 is prevented. Prevent surely. In other words, the backflow from the discharge path 11 to the second circuit 25 can be prevented by the sequence valve 28, but the backflow is reliably prevented even if there is internal pressure oil leakage or malfunction of the sequence valve 28. A second check valve 37 will be installed in the system.

The maximum internal pressure of the pressure accumulator 27 is regulated by providing a safety valve 38 between the pressure accumulator 26 and the pressure accumulator 27. In other words, when the internal pressure of the pressure accumulator 27 rises due to a peak pressure caused by sudden switching of the pressure accumulator valve 26 during pressure accumulation or an increase in the ambient temperature of the pressure accumulator 27, the safety valve 38 is released. The maximum pressure of the internal pressure is regulated so that the internal pressure does not become higher than the set pressure of the safety valve 38 by operating.

Next, a third embodiment of the present invention will be described. As shown in FIG. 4, the sequence valve 28 is of a variable set pressure type. For example, an electromagnetic variable set pressure type sequence valve 28 having a set pressure proportional to the amount of current supplied to the solenoid 28a is used. A third pressure sensor 39 for detecting the pressure of the second circuit 25 is provided, and the detected pressure is input to the controller 33.

The pressure is stored in the pressure accumulator 27 in the same manner as in the first embodiment. At this time, the amount of electricity to the solenoid 28 of the sequence valve 28 is increased to increase the set pressure.

Next, the first operation of reusing the stored high-pressure oil will be described. The energization of the solenoid 23 b of the recovery valve 23 is stopped to the closed position a, and the energization of the reservoir 26 and the solenoids 26 b and 30 Ob of the regeneration valve 30 are energized. To open position b. Set pressure of sequence valve 28 is high.

As a result, the high-pressure oil stored in the pressure accumulator 27 flows from the second circuit 25 into the main boat 24 of the second pump motor 17, and the second pump * motor Since 17 acts as a motor, the first pump 'motor 16' is driven. The second pump / motor 16 operates as a pump to discharge high-pressure oil to the first circuit 22, and the high-pressure oil is supplied from the third circuit 29 to the discharge path 11 of the main hydraulic pump 10. .

That is, as in the first embodiment, the pressure is supplied to the discharge path 11 of the main hydraulic pump 10 through the pressure converter 18 and the third circuit 29 for reuse.

Next, the second operation of reusing stored high-pressure oil will be described. 1 f

.

The energization of the solenoid 23 b of the recovery valve 23 is stopped to the closed position a, and the energization of the solenoid 26 b of the accumulation valve 26 is set to the open position b to regenerate. Valve 30 is in closed position a. Reduce the amount of electricity to the solenoid 28a of the sequence valve 28 to lower the set pressure.

As a result, the high-pressure oil stored in the pressure accumulator 27 is released from the second circuit.

From 25, it flows into the main port 24 of the second pump 'motor 17', and the second pump motor 17 acts as a motor so that the first pump-motor 17 The first circuit 22 connected to the main port 21 of the first pump module 16 has a recovery valve 23 and a regeneration valve.

Since it is closed at 30, the pressure oil discharged from the main port 21 of the first pump 16 stops at a dead end, and the set pressure of the sequence valve 28 stops. Since the pressure is low, the high-pressure oil stored in the pressure accumulator 27 is supplied from the sequence valve 28 to the discharge passage 11 of the main hydraulic pump 10.

Next, an operation of automatically selecting the first operation and the second operation will be described.

The controller 33 detects the internal pressure of the accumulator 27 (hereinafter referred to as the storage pressure) P 1 detected by the third pressure sensor 39 and the main hydraulic pump 1 detected by the first pressure sensor 31. A differential pressure P of the discharge pressure P 2 (load pressure) of 0 is calculated, and when this differential pressure Δ の is equal to or greater than the set differential pressure Δ Ρ1, it is determined to be the first operation, and the differential pressure △ P is set. When the pressure difference is equal to or less than ΔΡ1, it is determined that the operation is the second operation.

The set differential pressure Δ Ρ 1 is the horsepower loss due to the pressure transducer 18 and The horsepower loss due to the pressure loss of the sequence valve 28 is a pressure almost equal, for example, about 20 kg Zcm ² .

When the controller 33 determines that the operation is the first operation, the recovery valve 23, the pressure storage valve 26, and the regeneration valve 30 are switched as described above, and the set pressure of the sequence valve 28 is increased. And

When the controller 33 determines that the operation is the second operation, the controller 33 switches the recovery valve 23, the pressure accumulation valve 26, and the regeneration valve 30 as described above, and sets the sequence valve 28. The pressure is low.

Thus, when the pressure difference ΔP between the storage pressure P 1 and the discharge pressure P 2 is equal to or higher than the set pressure difference ΔP 1 (when the discharge pressure P 2 is low), the first operation is performed. That is, the stored high-pressure oil is supplied to the discharge path 11 of the main hydraulic pump 10 via the pressure converter 18 and the third circuit 29.

As a result, a large amount of low-pressure oil can be supplied to the discharge path 11 using the stored high-pressure oil. In other words, since the discharge pressure P 2 is low, the pressure supplied to the discharge path 11 may be low, and the swash plate angle of the second pump / motor 17 of the pressure transducer 18 is reduced to increase the speed. By rotating, the swash plate angle of the first pump / motor 16 is increased to decrease the discharge pressure, and the discharge amount is increased to supply a large amount of low-pressure hydraulic pressure to the discharge path 11.

When the pressure difference Δ の between the storage pressure P 1 and the discharge pressure P 2 is equal to or less than the set pressure difference ΔP 1 (when the discharge pressure P 2 is high), the stored high-pressure oil is supplied to the sequence valve 2. After that, it is supplied to the discharge path 11 of the main hydraulic pump 10.

Next, immediately without storing the energy of the recovered return pressure oil, The first operation that is reused in the following is described.

The recovery valve 23 is set to the open position b, the regeneration valve 30 and the pressure storage valve 26 are set to the closed position a, and the set pressure of the sequence valve 28 is set to a low pressure. As a result, the return pressure oil that has flowed into the first circuit 22 is boosted by the pressure transducer 18 as described above and discharged to the second circuit 25, and the pressure of the sequence valve 28 is increased. When the pressure is equal to or higher than the cut pressure, the pressure is directly supplied to the discharge path 11.

In this way, the pressure of the return pressure oil can be reduced by the pressure transducer 18 and supplied to the discharge path 11, so that the pressure of the return pressure oil is lower than the discharge pressure. Even if it is low, it can be reused immediately without storing.

Next, the second operation in which the energy of the collected return pressure oil is reused immediately without storing it will be described.

The recovery valve 23 and the regeneration valve 30 are set to the open position b, the pressure storage valve 26 is set to the closed position a, and the set pressure of the sequence valve 28 is set to a high pressure.

As a result, the return pressure oil flowing into the first circuit 22 is discharged to the second circuit 25 in the same manner as in the first operation, but the set pressure of the sequence valve 28 is high. Therefore, the return pressure oil flowing into the first circuit 22 is supplied to the discharge path 11 of the main pressure oil pump 10 from the regeneration valve 30 and the third circuit 29.

In this way, the return pressure oil can be directly supplied without passing through the pressure transducer 18, so that the return pressure oil can be efficiently returned when the pressure of the return pressure oil is higher than the discharge pressure. Pressure oil can be reused.

Next, an operation of automatically selecting the first operation and the second operation for immediately reusing the return pressure oil described above will be described. The controller 33 determines the magnitude of the discharge pressure P 2 from the first pressure sensor 31 and the pressure P 3 of the return pressure oil from the second pressure sensor 32, and determines P 3. When P2, the first operation is selected, and when P3> P2, the second operation is selected.

When the first operation is selected, the controller 33 switches the collection valve 23, the pressure storage valve 26, and the regeneration valve 30 in the same manner as described above, and lowers the set pressure of the sequence valve 28 to a low pressure. When the second operation is selected, the controller 33 switches the recovery valve 23, the pressure accumulation valve 26, and the regeneration valve 30 in the same manner as described above, and sets the sequence valve 28. Set the set pressure to high pressure.

Claims

The scope of the claims

1. Return of actuator operated by pressure oil of hydraulic power source First pump mechanically connected by energy of pressure oil • Motor 16 and second pump 'From motor 17 A pressure oil recovery and reuse system characterized by operating the pressure transducer 18 to supply high-pressure oil to the hydraulic source.

2. The main hydraulic pump 10 for supplying pressure oil to the actuator, the first circuit 22 to which the return pressure oil from the actuator is supplied, and the first circuit 22 are connected. A motor 16, a variable displacement type second pump motor 17 mechanically connected to the first pump motor 16 and connected to the second circuit 25, and A third circuit 29 communicating between the first circuit 22 and the discharge path 11 of the main hydraulic pump 10; a pressure reservoir 27 provided in the second circuit 25; and a third circuit 29 A pressure oil recovery and reuse system characterized by comprising a regeneration valve 30 that switches between a state in which flow is allowed and a state in which flow is blocked, and a regeneration system.

3. A pressure accumulator valve 26 is provided to communicate with and shut off the second circuit 25, and the main pump and the second pump 17 are located closer to the second pump 17 than the pressure accumulator valve 26 in the second circuit 25. The pressure oil recovery and reuse system according to claim 2, wherein a sequence valve (28) is provided between the pump (10) and the discharge path (11).

4. The main hydraulic pump 10 for supplying hydraulic oil to the factory, the first circuit 22 to which the return pressure oil from the factory is supplied, and the first circuit 22 First to allow oil flow The recovery valve 23 that switches between the state and the blocked second state, the first pump connected to the first circuit 22 and the first pump and the first pump Mechanically linked second circuit

The pressure transducer 18 provided with the variable displacement type second pump * motor 17 connected to 25, the first circuit 22 and the main hydraulic pump

A third circuit 29 communicating with the discharge passage 11 of the first circuit 10, a pressure accumulator 27 provided in the second circuit 25, and a third circuit 29 that allows a pressurized oil flow. A regeneration valve 30 for switching between a state and a second state for blocking, a pressure accumulation valve 26 for communicating with and shutting off the second circuit 25, and a pressure accumulation valve 26 for the second circuit 25. 2 A pump characterized by a variable set pressure sequence valve 28 provided between the pump 17 and the motor 17 and the discharge passage 11 of the main hydraulic pump 10. Oil recovery and reuse system.

5. First means for detecting the discharge pressure P 2 of the main hydraulic pump 10, second means for detecting the storage pressure P 1 of the pressure accumulator 27 of the second circuit 25, And the recovery valve 23, the pressure accumulation valve 26, and the regeneration valve based on the pressure detected by the

30 is provided, and a third means for changing the set pressure of the sequence valve 28 is provided. The third means is adapted to set the differential pressure between the storage pressure P1 and the discharge pressure P2 to a set pressure. When the pressure is equal to or higher than the pressure, the collection valve 23 is set to the second state, the pressure accumulating valve 26 is set to the communicating state, the regeneration valve 30 is set to the first state, and the set pressure of the sequence valve 28 is set to the high pressure. When the pressure difference between the storage pressure P 1 and the discharge pressure P 2 is equal to or lower than the set pressure difference, the recovery valve 23 and the regeneration valve 30 are set to the second state, and the pressure storage valve 26 is set to the communication state. , Sequence valve 28. The pressure oil recovery and reuse system according to claim 4, wherein the system has a function of lowering the set pressure of item 28.

6. First means for detecting the discharge pressure P 2 of the main hydraulic pump 10, third means for detecting the pressure P 3 of the return pressure oil of the first circuit 22, and the first means. And the third means for changing the set pressure of the sequence valve 28 by switching the recovery valve 23, the pressure accumulation valve 26, and the regeneration valve 30 based on the pressure detected by the third means. The third means includes: when the pressure P 3 is lower than the discharge pressure P 2, the recovery valve 23 is in the first state, the pressure accumulation valve 26 is shut off, and the regeneration valve 30 is in the third state. 2 and the set pressure of the sequence valve 28 is set to a low pressure, and when the pressure P 3 is higher than the discharge pressure P 2, the collection valve 23 and the regeneration valve 30 are set to the above-described state. In the first state, the storage valve 26 is shut off and the set pressure of the sequence valve 28 is increased. Pressure oil recovery and reuse system ranging fourth claim of claim to be.