JP2000145714A - Hydraulic circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic circuit suited for manual operation by a simple constitution with no limitation of use. SOLUTION: When an operation valve 20 is switched to a lower down position from a neutral condition as shown in Fig., a head port 8a of a hydraulic actuator 8 communicates with a second port 10b of a hydraulic device 10, a rod port 8b communicates with a first port 10a, and a piston rod 8c is lowered down by own weight of a dead weight load M, and when the operation valve is switched to a lift up position, the dead weight load M is pressed up by reversing communication of each port. Here, a control valve 11 controls the hydraulic device 10 so as to decrease or increase capacity ratio V2/V1 of the second port 10b to the first port 10a by a relation of a level between axial force acting on a valve unit of the control valve 11 of a differential pressure, between a pressure P3 in the upstream and a pressure P2 in the downstream of the operation valve 20, and spring force of a differential pressure setting spring 11a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic circuit used in all hydraulic devices of construction machines, ships, industrial machines and the like.

[0002]

2. Description of the Related Art Conventionally, as a hydraulic circuit of this type, a "hydraulic device for raising and lowering drive" previously filed by the present applicant (Japanese Patent Application No. Hei 9
No. 259850). As shown in FIG. 4, a vane-type hydraulic device 10 used for this purpose has a cam ring 1 formed in an oval shape and a number of vanes 2 slidable on the inner surface of the cam ring 1 in a vane holding groove 3a. And a rotating body 5 composed of a rotating shaft 4 and a rotor 3 which is loosely inserted radially.

One of a pair of port plates 6 and 6 provided on the cam ring 1 so as to sandwich both side surfaces of the rotor 3 (only one of them is shown in the figure) has a fluid suction stroke depending on the rotation direction of the rotor 3. And a first port 10a, a second port 10b, a third port 10c, and a fourth port 10d for performing any one of the discharge processes.

Then, the first port 10a is connected to the accumulator 7 via the first line L1 and the second port 10b
Is connected to the head port 8a of the hydraulic actuator 8 via the second conduit L2, the third and fourth ports 10c and 10d are both connected to the tank 9, and the cam ring 1 is controlled by the control valve 11. The cam ring is driven in the “+” or “−” direction by a hydraulic piston device 12 for driving the cam ring. The control valve 11 operates the position of the cam ring 1 by inputting a deviation signal between the moving speed of the piston rod 8c of the hydraulic actuator 8 and a speed command value given from outside and a signal corresponding to the displacement of the cam ring 1. It is controlled by the control device 13. The accumulator 7 is stored by a hydraulic pressure source (not shown).

When the cam ring 1 is at the position shown in FIG. 4, the pressure P1 of the accumulator 7 is applied to the first port 10a, and the pressure P2 of the head port 8a of the hydraulic actuator 8 is applied to the second port 10b. Act on the rotating shaft 4 via the vanes 2 to generate torques T1 and T2. At this time, if T1 = T2, the resultant torque becomes T1-T2 = 0, so that when the rotating body 5 is in the stopped state, that state is maintained as it is.

In this state, when the cam ring 1 is translated by the hydraulic piston device 12 in the "+" direction in FIG.
The capacity of the first port 10a increases,
The capacity of b decreases and the resultant torque becomes T1-T2> 0,
The rotating body 5 rotates in the arrow X direction. Thereby, the first,
The third ports 10a and 10c perform an expansion stroke, and the second and fourth ports 10b and 10d perform a compression stroke.

Therefore, the hydraulic fluid sucked into the first port 10a from the accumulator 7 by the motor action
Is discharged from the port 10d of the tank 9 to the tank 9 again.
From the second port 10b to the head port 8a of the hydraulic actuator 8 by a pump action, and drives the piston rod 8c in the protruding direction to increase the own weight load M. When the cam ring 1 is returned to the illustrated position where the resultant torque becomes zero by the hydraulic piston device 12 when the rising speed reaches a required value, the rotating body 5 rotates while maintaining the rotating speed,
It becomes a state in which feedback control is possible.

Conversely, when the cam ring 1 is moved in the "-" direction, the capacity of the first port 10a decreases and the capacity of the second port 10b increases, resulting in a combined torque T2-T1> 0.
And the rotating body 5 rotates in the direction indicated by the arrow Y. Thus, the first and third ports 10a and 10c are in a compression stroke, and the second and fourth ports 10b and 10d are in an expansion stroke.

Therefore, the hydraulic fluid on the head side of the hydraulic actuator 8 is sucked into the second port 10b by the action of the motor, discharged from the third port 10c to the tank 9, and again from the tank 9 to the fourth port 10d. Inhaled,
Due to the pumping action, the fluid is recovered from the first port 10a to the accumulator 7, the piston rod 8b contracts, and the dead weight load M falls. Then, when the cam ring 1 is returned to the illustrated position where the combined torque becomes zero at a predetermined timing, the rotating body 5 rotates while maintaining its rotation speed, and enters a feedback controllable state.

In such a vane type hydraulic device 10, the volumes of the first and second ports 10a and 10b communicating with the accumulator 7 and the hydraulic actuator 8 are V1, V2,
When the pressures are P1 and P2 and the volume ratio and the pressure ratio acting on the volume ratio are in a relationship of V2 / V1 = P1 / P2, the condition for balancing the rotating shaft 4 is satisfied.

According to such a hydraulic circuit, the energy sent from the accumulator 7 to the head side of the hydraulic actuator 8 via the vane-type hydraulic device 10 to raise the self-weight load M is equal to the energy of the self-weight load M. When it descends, it is collected by the accumulator 7 again, and significant energy saving can be achieved.

[0012]

However, in such a conventional hydraulic circuit, it is necessary to detect the moving speed of the piston rod of the hydraulic cylinder, the position of the cam ring, and the like, and feed it back to the control device. Therefore, there has been a problem that the production cost is increased and the supply cannot be performed at a low cost.

Further, since the control valve is automatically controlled by the control device, it is not suitable for a manually operated one such as a construction machine, for example, and the hydraulic actuator is driven only by its own weight. Therefore, there is also a problem that the application is limited to the self-weight load device. The present invention has been made in view of the above points, and has as its object to provide a hydraulic circuit that has a simple configuration, is suitable for manual operation, and has no limited use.

[0014]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a rotary member having a plurality of vanes or pistons which reciprocate in sliding contact with the inner surface of a cam ring, and which is expanded twice during one rotation. / Compression stroke, the first expansion /
The rotator rotates in a direction in which the torque received from the compression stroke and the torque received from the second expansion / compression stroke balance each other, and the torque received from each of the expansion / compression strokes is the difference between the communicating hydraulic pressure and its volume. Determined by the product,
By displacing the cam ring in the balanced state and operating the ratio of the volume of the first expansion / compression stroke to the volume of the second expansion / compression stroke, the hydraulic pressure ratio communicating with each of the strokes From a vane-type or radial-piston-type hydraulic device capable of controlling the pressure, a hydraulic actuator driven by the hydraulic device, and a meter-out throttle type directional flow control valve having a pressure extraction port from the hydraulic actuator. Operating valve, a hydraulic piston device for displacing the cam ring, a control valve for controlling communication of the hydraulic fluid to the hydraulic piston device, and a hydraulic fluid supplied from a hydraulic pressure source connected to an accumulator to perform the above operation. A first conduit forming a supply port to the valve, a second conduit forming a return port from the operation valve, and communicating with the hydraulic actuator; A third port for controlling the compression stroke of the hydraulic device to the first pipe, and a second port for controlling the expansion stroke to the second pipe. And a hydraulic circuit respectively connected to the hydraulic circuits.

In the above hydraulic circuit, the control valve has a differential pressure setting spring for setting a differential pressure between the pressure of the third or fourth conduit and the pressure of the second conduit. If the differential pressure between the pressure of the pressure extraction port and the pressure of the second conduit is equal to the spring force, if the axial force acting on the valve body is equal, the axial force is maintained. It is preferable to control the hydraulic pressure device so that the capacity ratio between the second port and the first port is decreased if the value is larger, and the capacity ratio is increased if the value is smaller.

Also, in the above-mentioned hydraulic circuit, a check valve for free-flowing in the direction of the first pipeline from a first port of the hydraulic device to a flow passage communicating with the first pipeline. It is even better to provide

The hydraulic circuit according to the present invention, which is constructed as described above, does not require feedback control of driving speed and the like, is suitable for manual operation, and has a very simple hydraulic circuit applicable to general loads. It can be obtained with a configuration.

[0018]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a circuit diagram of a main part showing a schematic configuration of the hydraulic device. Parts corresponding to those in FIG. And its detailed description is omitted.

The hydraulic circuit according to the present invention is different from the conventional hydraulic circuit shown in FIG. 4 in that a cam ring 1 for driving a cam ring 1 of a vane type hydraulic device (hereinafter referred to as "hydraulic device") 10 is provided. A control device 13 for feedback-controlling a control valve 11 for introducing a hydraulic fluid to a hydraulic piston device 12
Instead, an operation valve 20 which is a meter-out type manual (or stepping) directional flow control valve is inserted between the hydraulic device 10 and the hydraulic actuator 8, and the upstream and downstream sides of this operation valve are inserted. The point is that the hydraulic device 10 is operated so that the differential pressure becomes a predetermined value.

As shown in FIGS. 1 and 2, the operation valve 20 is a meter-out type flow control throttle 2 for controlling the flow returning from the hydraulic actuator 8 to the hydraulic device 10.
0a, 20b, and the third and fourth pipelines L on the upstream side thereof.
3 and L4 are connected to the left end side of the control valve 11 through the pilot line PL1 in the figure of the control valve 11, and the second line L2 downstream thereof is connected to the right end side of the control valve 11 through the pilot line PL2 in the figure. A differential pressure setting spring 1 is provided at both left and right ends of the control valve 11.
1a and 11a are provided.

The ports A and B of the control valve 11
Is a hydraulic piston device 12 for driving the cam ring shown in FIG.
Are connected to the first and second cylinders 12a and 12b. On the other hand, the accumulator 7 is connected to the first pipe line L1 and is connected to the accumulator 7 through a free-flow check valve 14 via a check valve 14. It is connected to a hydraulic pressure source 15 such as a pressure pump. The other configuration is the same as that of FIG.

Next, the operation of the embodiment having such a configuration will be described. In such a hydraulic device, the resultant torque of the rotating shaft 4 is constantly balanced, and the balance is only broken instantaneously during acceleration. When the combined torque of the rotating shaft 4 is balanced, as described above, the capacities of the first port 10a and the second port 10b of the hydraulic device 10 are V1 and V2, and the pressures are P1 and P2. Then, the capacity ratio V2 / V1 becomes equal to the pressure ratio P1 / P2. That is, V1 × P1
= V2 × P2 holds.

The flow control throttle 20a of the operation valve 20
The flow rate through a throttle such as 20b is equal to the differential pressure ΔP
It is publicly known that by keeping the constant, it is uniquely determined in proportion to the opening degree of the throttle. Here, the pressure at the pressure extraction port Pb upstream of the flow rate adjustment throttles 20a, 20b, which are meter-out throttles, is P3, the pressure downstream is P2,
If the differential pressure is ΔP, then P2 = P3−ΔP. Therefore, the first and second ports 10a, 1
By operating the capacity ratio V2 / V1 of 0b, it becomes possible to obtain a required pressure P2 from the pressure (accumulator pressure) P1 of the first port 10a.

From the fully closed state shown in FIGS.
0 is switched to the descending position and the first line L1 is switched to the third position.
In a state where the second pipe line L2 communicates with the fourth pipe line L4 to the pipe line L3, the piston rod 8c of the hydraulic actuator 8 descends due to the own weight of the own weight load M. Conversely, in the state where the operation valve 20 is switched to the up position and the first line L1 communicates with the fourth line L4 and the second line L2 communicates with the third line L3, the hydraulic pressure is reduced. The piston rod 8c of the actuator 8 extends to raise the own weight load M against its own weight.

By switching the operating valve 20 to the lowering position or the raising position, the pressure P3 on the head port 8a side or the rod port 8b side is controlled from the pressure outlet port Pb on the upstream side of the operating valve 20 via the pilot line PL1. It is led to the left end side of the valve 11. In addition, operating valve 2
The pressure P2 of the second line L2 downstream of 0 is guided to the right end side of the control valve 11 via the pilot line PL2.

At this time, the pressure P3 on the upstream side of the operation valve 20
Is high, in other words, when the brake pressure rises to the pressure P3, the differential pressure ΔP from the downstream pressure P2 also increases, and the valve body of the control valve 11 is actuated by the biasing force of the right differential pressure setting spring 11a. The port is connected to the first pipe line L1 and the port B is connected to the tank.

As a result, the pressure of the first cylinder 12a of the hydraulic piston device 12 communicating with the port A via the pilot line PL3 becomes higher than the pressure of the second cylinder 12b communicating with the port B, and The cam ring 1 of the device 10 is driven in the “+” direction in FIG. Due to the shift of the cam ring 1 in the "+" direction, the capacity V1 of the first port 10a increases, the capacity V2 of the second port 10b decreases, and the capacity ratio V2 / V1 decreases.

Here, the first port 10 of the hydraulic device 10
a to the accumulator 7 through the first line L1 and the flow rate of the hydraulic fluid flowing from the hydraulic actuator 8 to the second port 10b through the operation valve 20 and the second line L2. Assuming that the flow rate is QL, QR = (V1 / V
2) Since it is QL, a large amount of hydraulic fluid flows into the accumulator 7 and brake energy is recovered.

Conversely, when the pressure on the upstream side of the operation valve 11 is low, in other words, when the brake pressure does not rise at the pressure P3, the differential pressure ΔP from the pressure P2 on the downstream side also decreases, and the pressure of the control valve 11 decreases. The valve body is switched to the left from the illustrated neutral position, and port A communicates with the tank, and port B communicates with the first line L1.

As a result, the second hydraulic piston device 12
The pressure of the cylinder 12b becomes higher than the pressure of the first cylinder 12a, and the cam ring 1 of the hydraulic device 10 is driven in the "-" direction in FIG. Due to the shift of the cam ring 1 in the "-" direction, the capacity V1 of the first port 10a decreases, and the capacity V2 of the second port 10b increases, so that the capacity ratio V
2 / V1 increases. Therefore, in this state, as can be understood from the above-mentioned expression QR = (V1 / V2) QL, the flow rate of the hydraulic fluid to the accumulator 7 decreases, and unnecessary braking force decreases.

As described above, according to this embodiment, when a high brake pressure is required, the capacity ratio V
Operate the cam ring 1 so that 2 / V1 approaches 0,
When the brake pressure is unnecessary, the above-mentioned capacity ratio V2 / V1
It is only necessary to operate the cam ring 1 so that is brought closer to ∞.

As a result, in the former case, when the capacity V1 of the first port 10a is large, the rotating body 5 rotates in the direction of the arrow Y, and a large amount of hydraulic fluid flows into the accumulator 7 and the brake is applied. Energy is recovered. In the latter case, the rotating body 5 rotates in the direction indicated by the arrow Y in a state where the capacity of the first port 10a is small, so that the hydraulic fluid hardly flows into the accumulator 7, and unnecessary brake pressure is reduced. Does not occur.

The hydraulic device 10 in this hydraulic circuit is generally called a "transformer" (transformer). When controlling the flow of the second line L2 shown in FIG. Since the energy is recovered by adjusting the pressure P2 on the downstream side of the flow control throttles 20a and 20b of the valve 20, usually the first port 10a
It operates in the direction of the flow from the control valve 20 to the operation valve 20.

According to the above-described embodiment, the hydraulic device 10 can be operated so that the differential pressure between the upstream side and the downstream side becomes a predetermined value only by switching the operation valve 20. Therefore, there is no need for troublesome feedback control, and supply can be performed at low cost. This is particularly suitable for the field of manual operation such as construction equipment. Further, since the double-acting hydraulic cylinder is used as the hydraulic actuator, the hydraulic actuator is not limited to the drive for raising and lowering the load of its own weight, but can be applied to a general load.

FIG. 3 shows another embodiment of the present invention in which a part of the hydraulic circuit shown in FIG. 1 is modified. In this hydraulic circuit, the first port 1 of the hydraulic device 10
0a and a fifth pipe line L5 that communicates a pipe line from the connection of the accumulator 7 of the first pipe line L1 to the operation valve 20;
The check valve 21 for free flow is inserted from the hydraulic device 10 in the direction of the first pipe line L1, and the other configuration is the same as that of FIG.

By providing the check valve 21, for example, when the operating valve 20 is fully closed and the hydraulic device 10 is not operated, the hydraulic fluid supplied from the accumulator 7 to the first port 10a is connected to the vane 2 by the vane 2. It is possible to prevent a loss of energy caused by leaking into the tank 9 through the slight gap formed between the cam ring 1 and the fourth port 10d.

Further, in the case where the operation valve 20 is suddenly closed while the own weight load M is moving up and down at a constant speed,
It is also possible to prevent the hydraulic device 10 from reversing, causing a reverse flow in the second pipe line L2 and increasing the pressure P2, which may cause a failure.

In the above-described embodiment, the case where a vane type hydraulic device is used as the hydraulic device has been described. However, a radial piston type hydraulic fluid in which a piston or a plunger slides on the inner surface of a cam ring and reciprocates in a radial direction. A pressure device may be used. Also, a proportional electromagnetic control valve that can be remotely operated can be used instead of the operating valve, and the hydraulic actuator may use a hydraulic motor instead of the hydraulic cylinder.

[0039]

As described above, according to the hydraulic circuit according to the present invention, it is not necessary to detect the speed of the hydraulic actuator or the hydraulic device and feed it back to the control device.
A hydraulic circuit capable of greatly saving energy with a simple configuration can be supplied at low cost, and is suitable for manual operation of construction machines and the like. At the same time, the present invention is not limited to the self-weight load device, but can be applied to general loads and is convenient.

In the above-mentioned hydraulic circuit, the control valve has a differential pressure setting spring for adjusting the differential pressure between the second and third conduits, and the spring force and the differential pressure are applied to the valve body. By controlling the hydraulic device according to the magnitude of the acting axial force, the hydraulic device can be controlled very accurately with a simple configuration.

Further, in the above-mentioned hydraulic circuit, the first port of the hydraulic device is connected to the first conduit in the flow path communicating with the first conduit.
By providing a free-flow check valve in the direction of the pipeline,
If the hydraulic valve is not operated when the operation valve is fully closed, energy loss due to leakage of hydraulic fluid in the accumulator to the tank is prevented, and at the same time, the operation valve is suddenly operated while the load is moving at a constant speed. In such a case, it is possible to prevent the hydraulic device from reversing, thereby reducing the possibility of failure.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of the present invention.

FIG. 2 is a circuit diagram of a main part showing a schematic configuration of the hydraulic device.

FIG. 3 is a circuit diagram showing another embodiment of the present invention.

FIG. 4 is a circuit diagram showing an example of a conventional hydraulic circuit.

[Explanation of symbols]

 1: cam ring 2: vane 3: rotor 4: rotating shaft 5: rotating body 6: port plate 7: accumulator 8: hydraulic actuator 9: tank 10: vane-type hydraulic device 10a to 10d: first to fourth ports 11: Control valve 11a: Differential pressure setting spring 12: Hydraulic piston device 14: Check valve 15: Hydraulic pressure source 20: Operating valve 21: Check valve L1 to L5: First to fifth pipelines PL1 to PL4 : Pilot pipeline M: Self-weight load

Claims (3)

[Claims] 1. A rotating body having a plurality of vanes or pistons reciprocating in sliding contact with an inner surface of a cam ring has two expansion / compression strokes during one rotation, and has a first expansion / compression stroke.
The rotator rotates in a direction in which the torque received from the compression stroke and the torque received from the second expansion / compression stroke balance each other, and the torque received from each of the expansion / compression strokes is the difference between the communicating hydraulic pressure and its volume. Determined by the product,
By displacing the cam ring in the balanced state and operating the ratio between the volume of the first expansion / compression stroke and the volume of the second expansion / compression stroke, the hydraulic pressure ratio communicating with each of the strokes From a vane-type or radial-piston type hydraulic device capable of controlling a hydraulic device, a hydraulic actuator driven by the hydraulic device, and a meter-out throttle type directional flow control valve having a pressure extraction port from the hydraulic actuator. An operating valve, a hydraulic piston device for displacing the cam ring, a control valve for controlling the communication of the hydraulic fluid to the hydraulic piston device, and a hydraulic fluid supplied from a hydraulic pressure source connected to an accumulator. A first conduit forming a supply port to a valve, a second conduit forming a return port from the operation valve, and communicating with the hydraulic actuator A first port for controlling a compression stroke of the hydraulic device;
A hydraulic circuit, wherein a second port for performing an expansion process is communicated with the second pipeline. 2. The differential pressure setting spring according to claim 1, wherein the control valve sets a differential pressure between the pressure of the third or fourth conduit and the pressure of the second conduit. With respect to the spring force, the differential pressure between the pressure of the pressure extraction port and the pressure of the second conduit is maintained in a neutral state if the axial force acting on the valve body is equal. If the axial force is larger, the capacity ratio between the second port and the first port of the hydraulic device is decreased, and if the axial force is smaller, the capacity ratio is increased. Characteristic hydraulic circuit. 3. The hydraulic circuit according to claim 1, wherein a flow path communicating from the first port of the hydraulic device to the first conduit is free in the direction of the first conduit. A hydraulic circuit comprising a flow check valve.