JPH08219004A - Capacity control device of hydraulic rotary machine - Google Patents

Abstract

PURPOSE: To change over the displacement of a hydraulic rotary machine (hydraulic motor) smoothly and stably and allow smooth changing-over of the running speed, etc. CONSTITUTION: A selector valve device 4 to supply and exhaust a pressure oil to/from the oil pressure chamber 3A of a variable displacement actuator 3 is equipped with a pressure oil supply/discharge port 4A in connection with the oil pressure chamber 3A, a high pressure port 4B in connection with a shuttle valve 16, and a tank port 4C. A hydraulic pilot type displacement selector valve 5 is installed between the pressure oil supply/discharge port 4A, high pressure port 4B, and tank port 4C, and a flow control valve 8 consisting of a stationary throttle 6 and decompression valve 7 is installed between the port 4A and tank port 4C. When the valve 5 is switched to the changeover position (5) by a spring 5A, the oil discharged from the oil pressure chamber 3A of the actuator 3 to the tank port 4C via the port 4A is subjected to rate-of-flow control with the stationary throttle 6 and pressure reducing valve 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a displacement control device for a hydraulic rotary machine which is provided in a construction machine such as a hydraulic excavator and is preferably used for controlling the displacement of a hydraulic pump, a hydraulic motor or the like.

[0002]

2. Description of the Related Art Generally, a variable displacement type hydraulic rotary machine having a variable capacity section and a hydraulic pressure rotary machine for driving the variable capacity section of the hydraulic rotary machine by supplying and discharging pressure oil. A variable capacity actuator that switches the capacity between small capacity and large capacity,
A capacity switching valve that switches between a small capacity position and a large capacity position according to a pilot pressure from the outside, and selectively connects the pressure oil supply / discharge port connected to the variable capacity actuator to the high pressure port and the tank port. A capacity control device for a hydraulic rotary machine, which comprises an operating means for capacity switching that changes the pilot pressure supplied to the capacity switching valve, is disclosed in Japanese Patent Publication No.
-55714 (JP-A-61-49175)
And so on.

In a displacement control device for a hydraulic rotary machine according to this type of prior art, the operating means is operated to change the pilot pressure supplied to the displacement switching valve, and the pressure of the displacement switching valve is changed according to the pilot pressure. By selectively connecting the oil supply / discharge port to the high pressure port and the tank port, the pressure oil to be supplied / discharged to / from the variable displacement actuator is switched and controlled, and the variable displacement actuator allows the variable displacement portion of the hydraulic rotary machine to operate. By tilting, the capacity of the hydraulic rotary machine is switched between a small capacity and a large capacity.

When the hydraulic rotating machine is used as a hydraulic motor, for example, when the load pressure is small, the motor capacity is switched to a small capacity so that the motor rotates at a high speed with a small torque. When it becomes large, the capacity is switched to a large capacity to rotate at a low speed with a large torque, thereby suppressing a large increase in the load pressure and preventing an overload from acting on the hydraulic pump, for example.

Further, when the hydraulic motor is constructed as, for example, a variable displacement type swash plate type hydraulic rotating machine, the hydraulic motor includes a motor casing, a rotary shaft rotatably provided in the motor casing, A cylinder block that is connected to the rotary shaft and rotates integrally with the rotary shaft; a plurality of plungers (pistons) slidably inserted into the cylinders provided in the cylinder block; Along with this, a pair of kidney ports (supply / discharge ports) for supplying / discharging pressure oil to / from each cylinder, a plurality of shoes swingably mounted on the projecting end side of each plunger, and the respective shoes slidingly contacting each other, and hydraulic pressure is applied. A swash plate that serves as a variable capacity part of the rotating machine,
A hydraulic drive member as a variable displacement actuator that switches the motor capacity between a small capacity and a large capacity by tilting the swash plate is generally configured.

When this variable displacement type swash plate type hydraulic rotary machine is used as, for example, a traveling hydraulic motor of a hydraulic excavator (vehicle), pressure oil is supplied into each cylinder from a pair of kidney ports (supply / discharge ports). Is supplied to and discharged from each cylinder, and each plunger (piston) is reciprocated in each cylinder, whereby the cylinder block is rotationally driven together with the rotation shaft to drive the vehicle on the road.

In this case, when the load pressure is small, such as when traveling on level ground, the displacement variable actuator (hydraulic drive member) tilts the swash plate toward the small tilt side to switch the motor capacity to the small capacity. Thus, the rotary shaft of the hydraulic motor is rotated at high speed with a small torque together with the cylinder block. Further, when the load pressure becomes large, such as when traveling uphill on a slope, the variable displacement actuator (hydraulic drive member) tilts the swash plate toward the large tilt side to switch to a large capacity, thereby rotating the rotary shaft to the cylinder. The block is rotated with a large torque at a low speed.

[0008]

By the way, in the above-mentioned prior art, when, for example, a driver of a hydraulic excavator switches the operating means for switching the capacity, the capacity is switched according to the pilot pressure from the operating means. By selectively connecting the pressure oil supply / discharge port of the valve to the high pressure port and the tank port, the motor capacity of the hydraulic motor can be switched between a small capacity and a large capacity in two stages, so that the motor capacity is switched. The discharge pressure and the discharge flow rate of the hydraulic pump may suddenly change at an instant, and for example, in a traveling hydraulic motor, the traveling speed changes abruptly when the capacity is switched, which causes a problem that the ride comfort of the driver deteriorates. Further, even when used as a hydraulic pump, there are similar problems.

Particularly, when the displacement switching valve is switched by the operating means so that the pressure oil supply / discharge port of the displacement switching valve communicates with the tank port, for example, in the case of a swash plate type hydraulic motor, each plunger (piston) to the swash plate is connected. Pressure oil (oil liquid) in the variable capacity actuator due to the oil pressure (pressing force) acting on the
Is rapidly discharged to the tank port side via the pressure oil supply / discharge port.

As a result, the tilt angle of the swash plate changes abruptly,
There is a problem that the driver is vibrated or shocked due to a sudden change in the traveling speed of the vehicle. The same problem arises even with a variable displacement oblique shaft hydraulic motor (pump) or a radial piston hydraulic motor (pump).

The present invention has been made in view of the above-mentioned problems of the prior art. The present invention can smoothly and stably switch the capacity of the hydraulic motor (hydraulic pump), and the pressure and flow rate in the hydraulic circuit can be sharply changed. It is possible to provide a displacement control device for a hydraulic rotary machine, which can effectively prevent a change in the vehicle speed and can smoothly change, for example, the traveling speed and the like, and surely improve the ride comfort of the driver. Has an aim.

[0012]

In order to solve the above-mentioned problems, the present invention relates to a variable displacement type hydraulic rotary machine having a variable capacity section, and a hydraulic rotary machine by supplying and discharging pressure oil. A variable capacity actuator for driving the variable capacity part of the hydraulic rotary machine to switch the capacity of the hydraulic rotary machine between a small capacity and a large capacity, and a pressure oil supply / discharge port, a high pressure port and a tank port connected to the variable capacity actuator. By selectively communicating the pressure oil supply / discharge port with the high pressure port and the tank port, there is provided capacity switching means for supplying / discharging the pressure oil from the high pressure port to / from the variable capacity actuator via the pressure oil supply / discharge port. It is applied to the capacity control device of a hydraulic rotary machine equipped with it.

The feature of the configuration adopted by the invention of claim 1 is that the tank port and the pressure oil supply / discharge port communicate with each other between the pressure oil supply / discharge port and the tank port of the capacity switching means. Occasionally, depending on the pressure generating portion that generates pressure in the oil liquid discharged from the pressure oil supply / discharge port to the tank port side, and the pressure generated in the pressure generating portion that is located upstream of the pressure generating portion. This is because a flow rate control valve including a variable throttle portion that changes the flow passage area is provided.

Further, a feature of the structure adopted by the invention as set forth in claim 2 is that the capacity switching means is switched by a spring so that the pressure oil supply / discharge port communicates with the tank port, and the pilot. The pressure oil is located between a second switching position, which is switched against the spring by pressure so as to communicate the pressure oil supply / discharge port with the high pressure port, and the second switching position and the first switching position. It is constituted by a hydraulic pilot type switching valve having an intermediate position for shutting off the supply / discharge port from the tank port and the high pressure port, and the switching valve is provided between the pressure oil supply / discharge port and the tank port. And a pressure generation section for generating a pressure in the oil liquid discharged from the pressure oil supply / discharge port to the tank port side when switching from the switching position to the first switching position. Located at Depending on the pressure generated by the parts in the provision and switching control unit for switching the switching valve to the intermediate position.

In this case, as in the invention described in claim 3, the switching valve is provided with the pressure oil supply / discharge port, the high pressure port,
A valve casing having a tank port and a pilot port formed therein; and a spool slidably fitted in the valve casing for selectively communicating and blocking the pressure oil supply / discharge port with the high pressure port and the tank port. A spring chamber formed between one end side of the spool and the valve casing and always communicating with the tank port; a spring arranged in the spring chamber for constantly biasing the spool in the axial direction; A hydraulic pilot portion that is located at the end side and that is formed in the valve casing and is supplied with pilot pressure from the pilot port to slide and displace the spool against the spring, and slide in the spool. It is configured to include a piston that is inserted and fitted so that one end side forms the switching control section with the spool and the other end side projects into the hydraulic pilot section. Masui.

Further, according to a fourth aspect of the present invention, the spool has a first passage for communicating and blocking the pressure oil supply / discharge port with respect to the high pressure port, and is separated from the first passage. A second passage that connects and disconnects the pressure oil supply / discharge port with respect to the tank port, a small diameter throttle passage that is formed between the spring chamber and the switching control portion and that constitutes the pressure generating portion, and In order to guide the oil liquid from the pressure oil supply / discharge port into the switching control unit, it is preferable to provide a communication passage that constantly connects the switching control unit and the second passage.

[0017]

With the above construction, in the invention described in claim 1,
When the pressure oil supply / discharge port of the capacity switching unit is connected to the tank port to switch the capacity of the hydraulic rotary machine, pressure is applied to the oil liquid discharged from the pressure oil supply / discharge port to the tank port at the pressure generator. The pressure oil in the variable displacement actuator can be generated and the flow passage area of the variable throttle unit can be changed according to the pressure generated in the pressure generating unit, and the flow rate of the discharged oil is controlled (limited). It is possible to reliably prevent the (oil liquid) from being rapidly discharged to the tank port side via the pressure oil supply / discharge port.

According to the second aspect of the invention,
The capacity switching means is constituted by a hydraulic pilot type switching valve in an intermediate position between the second switching positions, which shuts off the pressure oil supply / discharge port from the tank port and the high pressure port, and the switching valve further comprises the second switching valve. Since the switching control section for switching the switching valve to the intermediate position according to the pressure generated in the pressure generating section is provided when switching from the switching position of 1 to the first switching position,
When the switching valve is first switched to the first switching position by a spring in order to switch the capacity of the hydraulic rotary machine, and when the pressure oil supply / discharge port is communicated with the tank port, the pressure generation unit transfers the pressure oil supply / discharge port to the tank port. A pressure can be generated in the oil liquid discharged to the side, and the switching valve can be switched from the first switching position to the intermediate position by applying this pressure to the switching control unit.

When the switching valve is in the intermediate position, the pressure oil supply / discharge port is shut off from the tank port, so that the pressure generated in the pressure generating section is reduced, and the switching control section causes the switching valve to operate. It allows the switching from the intermediate position to the first switching position again. As a result, the switching valve repeatedly operates to switch between the first switching position and the intermediate position, and the oil liquid discharged from the variable capacity actuator to the tank port via the pressure oil supply / discharge port (discharge oil). It is possible to reliably prevent the oil liquid at this time from being rapidly discharged to the tank port side via the pressure oil supply / discharge port.

In this case, the switching valve is constituted by the valve casing, the spool, the spring, the hydraulic pilot portion, and the piston, so that the spring normally biases the spool in the axial direction. Therefore, the pressure oil supply / discharge port can be communicated with the tank port with the switching valve as the first switching position. Further, when the pilot pressure supplied to the hydraulic pilot portion is increased and the spool is slidably displaced against the spring, the switching valve is set to the second position.
Can be switched to the switching position, and the pressure oil supply / discharge port can be communicated with the high pressure port.

When the switching valve switches from the second switching position to the first switching position, the pressure from the pressure generating portion acts on the switching control portion formed between the one end side of the piston and the spool. By doing so, the spool can be slidably displaced against the spring by the pressure at this time to temporarily switch to the intermediate position, and the pressure oil supply / discharge port is blocked from the high pressure port and the tank port, and the capacity is The pressure oil (oil liquid) in the variable actuator can be stopped from being discharged to the tank port side via the pressure oil supply / discharge port.

Further, according to the invention of claim 4, the spool has a first passage, a second passage, a small-diameter throttle passage forming a pressure generating portion, and the second passage as a switching control portion. By providing the communication passage which is always communicated, the spool is slidably displaced by the spring to switch the capacity of the hydraulic rotary machine, and the pressure oil supply / discharge port is communicated with the tank port through the second passage of the spool. When the oil is discharged from the variable capacity actuator to the tank port side through the pressure oil supply / discharge port, a throttle pressure can be generated in the throttle passage, and this pressure is applied to the switching control section to cause the spool controller to operate. Can be slidably displaced against the spring, and the communication between the pressure oil supply / discharge port and the tank port via the second passage can be temporarily cut off.

In this state, the pressure oil supply / discharge port is shut off from the tank port, so that the flow rate of the oil liquid flowing through the throttle passage is decreased and the pressure in the switching control unit is decreased. Therefore, the spool can be pushed back by the spring, and the pressure oil supply / discharge port can be communicated with the tank port again in the second passage of the spool. As a result, the spool is slidably displaced so that the pressure oil supply / discharge port and the tank port are repeatedly connected and disconnected in the second passage in accordance with the increase / decrease of the pressure in the switching control unit, and the capacity is changed. Oil liquid (discharge oil) discharged from inside the actuator to the tank port through the pressure oil supply / discharge port
The flow rate can be limited.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A displacement control device for a hydraulic rotary machine according to an embodiment of the present invention is applied to a traveling hydraulic motor and a traveling hydraulic circuit of a hydraulic excavator based on FIGS. 1 to 6 as an example. Explain.

Here, FIG. 1 shows a first embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a variable displacement hydraulic motor which constitutes a traveling hydraulic motor.
Is composed of swash plate type or swash axis type hydraulic rotary machine,
For example, it has a capacity varying unit 2 formed of a swash plate or a valve plate. The variable capacity unit 2 is tilted and driven by a variable capacity actuator 3 to be described later in the directions A and B, and when the tilt angle becomes maximum in the direction A, the motor capacity of the hydraulic motor 1 is increased. When the tilt angle becomes the minimum in the direction of arrow B, the motor capacity is set to a small capacity.

Reference numeral 3 denotes a variable displacement actuator attached to the hydraulic motor 1. The variable displacement actuator 3 has a tilting piston 3B defining a hydraulic chamber 3A, and the tilting piston 3B is provided in the hydraulic chamber 3A. It is driven in the directions of arrows A and B by the supplied and discharged pressure oil, and the capacity variable portion 2 of the hydraulic motor 1
Is tilted to the maximum tilt side and the minimum tilt side.

Reference numeral 4 denotes a switching valve device as a capacity switching means for switching and controlling the pressure oil supplied to and discharged from the variable displacement actuator 3. The switching valve device 4 is connected to the hydraulic chamber 3A of the variable displacement actuator 3. It has a supply / discharge port 4A, a high pressure port 4B connected to a shuttle valve 16 described later, and a tank port 4C. The switching valve device 4 includes a capacity switching valve 5 including a hydraulic pilot type switching valve between the pressure oil supply / discharge port 4A, the high pressure port 4B, and the tank port 4C.
Between the pressure oil supply / discharge port 4A and the tank port 4C, a flow rate control valve 8 including a fixed throttle 6 serving as a pressure generating portion and a pressure reducing valve 7 serving as a variable throttle portion is provided.

Here, the capacity switching valve 5 of the switching valve device 4 is
It has a spring 5A and a hydraulic pilot portion 5B, and is constantly switched to the switching position (a) as the large capacity position by the spring 5A, and when the pilot pressure supplied to the hydraulic pilot portion 5B rises, the spring 5A is resisted. Then, it is switched to the switching position (b) as the small capacity position. The capacity switching valve 5 supplies the pressure oil from the shuttle valve 16 to the hydraulic chamber 3A of the capacity variable actuator 3 by connecting the high pressure port 4B to the pressure oil supply / discharge port 4A at the switching position (b). Tilt piston 3B of the variable capacity actuator 3
Is driven in the direction of arrow B.

When the capacity switching valve 5 is switched to the switching position (a) by the spring 5A, the pressure oil supply / discharge port 4A is communicated with the tank port 4C, so that the capacity variable actuator 3 moves from the hydraulic chamber 3A. Pressure oil (oil liquid)
Is discharged to the tank port 4C side via the pressure oil supply / discharge port 4A, and the tilting piston 3B of the variable capacity actuator 3 is discharged.
Is driven in the direction of arrow A. At this time, the fixed throttle 6 exerts a throttle action on the oil liquid discharged from the pressure oil supply / discharge port 4A to the tank port 4C side to generate a pressure on the upstream side of the fixed throttle 6.

The pressure reducing valve 7 operates so as to close when the pressure at this time rises above the set pressure of the spring 7A, and the pressure generated between the pressure reducing valve 7 and the fixed throttle 6 increases or decreases. The flow path area is reduced or increased. Thus,
The fixed throttle 6 and the pressure reducing valve 7 constitute a flow rate control valve 8, and control the flow rate of the oil liquid discharged from the hydraulic chamber 3A of the variable capacity actuator 3 to the tank port 4C side via the pressure oil supply / discharge port 4A ( Restrictions).

Reference numeral 9 denotes a hydraulic pump which constitutes a main hydraulic source together with the tank 10. The hydraulic pump 9 is rotationally driven by a prime mover (not shown) and discharges the hydraulic oil sucked from the tank 10 as high pressure oil. Is. The hydraulic pump 9 and the tank 10 are connected to the hydraulic motor 1 through the main conduit 11
It is connected via A and 11B.

Reference numeral 12 denotes a traveling control valve provided in the middle of the main pipelines 11A and 11B. The control valve 12 is operated from the neutral position (a) to the switching position (b) by the operating lever 12A.
It is switched to (C), and the direction of the pressure oil supplied to and discharged from the hydraulic pump 9 to the hydraulic motor 1 is switched at the switching positions (B) and (C). Further, the control valve 12 is a normally open type directional control valve, and when the inside of the main pipeline 11A or 11B has a negative pressure at the neutral position (a), the tank 10 is placed in the main pipeline 11A (11B). The hydraulic oil inside is replenished.

13A and 13B are hydraulic motor 1 and control valve 1
2, a pair of check valves provided in the middle of the main pipelines 11A, 11B, 14 is the check valve 13A,
13B shows a counterbalance valve provided in the middle of the main pipelines 11A and 11B so as to be in parallel with 13B, and the counterbalance valve 14 is switched almost in conjunction with the control valve 12 by the pressure difference between the main pipelines 11A and 11B. When the hydraulic motor 1 is rotated by inertia, the valve is closed as shown in the figure.
Brake pressure is generated in the main pipeline 11A or 11B before and after.

Denoted at 15A and 15B are a pair of overload relief valves provided between the hydraulic motor 1 and the counterbalance valve 14 (check valves 13A and 13B) and provided in the middle of the main pipelines 11A and 11B. The overload relief valves 15A and 15B are opened when the brake pressure rises to a predetermined set pressure when the hydraulic motor 1 is stopped, etc., and the excess pressure at this time is relieved to act on the hydraulic motor 1 and the like. To prevent this.

A shuttle valve 16 is provided between the hydraulic motor 1 and the counter balance valve 14 (check valves 13A and 13B) and is provided between the main pipe lines 11A and 11B as a high pressure selection valve. Is the main pipeline 11A, 11
High pressure side pressure oil (usually the motor drive pressure of the hydraulic motor 1) is selected from B, and this pressure oil is supplied to the hydraulic chamber 3A of the variable capacity actuator 3 via the control line 17 and the capacity switching valve 5 and the like. Is to be supplied to.

Reference numeral 18 denotes a pilot pump which constitutes a pilot hydraulic pressure source together with the tank 10. Reference numeral 19 denotes a capacity selection valve for switching and connecting the pilot pump 18 and the tank 10 to the pilot conduit 20. The capacity selection valve 19 is a hydraulic motor. The operating means for switching the motor capacity of No. 1 is configured, and the driver tilts the operation lever 19A to selectively switch between the large capacity position (c) and the small capacity position (d).

Further, reference numeral 21 denotes a pressure reducing valve provided between the pilot pump 18 and the capacity selecting valve 19, which reduces the pilot pressure when the capacity selecting valve 19 is switched to the small capacity position (d). Pump 18 to pilot line 20
The pilot pressure supplied to the inside is reduced to a pressure Pa lower than the set pressure of the relief valve 22. When the switching set pressure by the spring 5A of the capacity switching valve 5 is pressure Pb, the pressure Pa set by the pressure reducing valve 21 is

[0039]

[Equation 1] The relation Pa> Pb is satisfied, and the switching set pressure (pressure P
b) higher pressure than that set.

The displacement control device for a hydraulic rotary machine according to this embodiment has the above-mentioned structure, and its operation will be described below.

First, the capacity selection valve 19 is set to the large capacity position (c).
In the state where the pilot line 20 is switched to the tank 10,
To the tank pressure, the capacity switching valve 5 is switched to the switching position (a) by the spring 5A, and the switching valve device 4 causes the pressure oil supply / discharge port 4A to communicate with the tank port 4C and the variable capacity actuator 3 By discharging the oil liquid from the hydraulic chamber 3A to the tank port 4C side via the pressure oil supply / discharge port 4A, the tilting piston 3B of the variable capacity actuator 3 is driven in the direction of arrow A, and the motor of the hydraulic motor 1 is driven. Set the capacity to the high capacity state.

Then, in this state, the control valve 12 is switched from the neutral position (a) to the switching positions (b) and (c), and the pressure oil from the hydraulic pump 9 is supplied to and discharged from the hydraulic motor 1. The hydraulic motor 1 is driven to rotate with high torque by the pressure, and the hydraulic excavator (vehicle) can be driven at a low speed. In this case, since the motor capacity is large and the load pressure of the hydraulic motor 1 can be suppressed from increasing significantly, it is possible to prevent the discharge pressure of the hydraulic pump 9 from becoming excessively high, and it is possible to prevent the prime mover from exceeding. It is possible to prevent a load from acting and to smoothly run uphill.

Next, the capacity selection valve 19 is set to the small capacity position (d).
When switching to, the pressure Pa set by the pressure reducing valve 21
Is supplied to the hydraulic pilot portion 5B of the capacity switching valve 5 via the pilot conduit 20,
The capacity switching valve 5 is switched from the switching position (a) to the switching position (b) against the spring 5A. As a result, the switching valve device 4
The high pressure port 4B communicates with the pressure oil supply / discharge port 4A, and the pressure oil from the shuttle valve 16 is supplied to the hydraulic chamber 3A of the capacity variable actuator 3 via the control pipe 17, whereby the capacity variable actuator 3 Is a tilting piston 3B for tilting the variable capacity portion 2 in the direction of arrow B toward the small tilting side,
The motor capacity of the hydraulic motor 1 is set to a small capacity state.

The hydraulic motor 1 is rotated at high speed with low torque by supplying and discharging the pressure oil from the hydraulic pump 9, so that the hydraulic excavator (vehicle) can run at high speed. In this case, the hydraulic motor 1 has a small motor capacity, and the hydraulic motor 1 can rotate at a low torque and a high speed according to the flow rate of the pressure oil supplied and discharged via the control valve 12. The vehicle can be driven on the road at a high speed when traveling on a level ground where the load pressure acting on the vehicle is small.

By the way, when the hydraulic motor 1 is set in a small capacity state and the vehicle approaches an uphill while traveling on a level ground,
Since the load pressure of the hydraulic motor 1 increases and the discharge pressure (motor drive pressure) of the hydraulic pump 9 correspondingly increases, the displacement selection valve 19 is set to the small capacity position (d) while the motor drive pressure is increased. When the switch is switched from the large capacity position (c) to the large capacity position (c), the capacity switching valve 5 is switched to the switching position (a) by the spring 5A, and the pressure oil supply / discharge port 4A of the switching valve device 4 communicates with the tank port 4C. Pressure oil (oil liquid) flows from the hydraulic chamber 3A of the variable displacement actuator 3 to the pressure oil supply / discharge port 4A.
May be rapidly discharged to the tank port 4C side via the.

In particular, the high-pressure motor drive pressure acts as a pressing force in the direction of arrow A on the variable volume portion 2 such as the swash plate and the valve plate, so that the variable volume actuator 3 receives from the hydraulic chamber 3A. The pressure oil (oil liquid) tends to be rapidly discharged to the tank port 4C side via the pressure oil supply / discharge port 4A, and when the tilt angle of the capacity varying section 2 changes abruptly, the traveling speed of the vehicle changes. The sudden change causes vibration or shock to the driver.

Therefore, in this embodiment, a flow rate control valve 8 consisting of a fixed throttle 6 and a pressure reducing valve 7 is provided between the pressure oil supply / discharge port 4A and the tank port 4C of the switching valve device 4 and the capacity switching valve is provided. 5 is switched to the switching position (a) by the spring 5A, the pressure oil supply / discharge port 4A is communicated with the tank port 4C, and the pressure oil supply / discharge port 4A is connected to the tank port 4C.
The fixed throttle 6 exerts a throttling action on the oil liquid discharged to the side to generate pressure on the upstream side of the fixed throttle 6, and the pressure reducing valve 7
On the side, the flow passage area of the pressure reducing valve 7 is decreased or increased as the pressure at this time increases or decreases.

As a result, the oil liquid discharged from the hydraulic chamber 3A of the variable displacement actuator 3 to the tank port 4C side via the pressure oil supply / discharge port 4A by the flow control valve 8 consisting of the fixed throttle 6 and the pressure reducing valve 7. Can control (limit) the flow rate of
It is possible to reliably prevent pressure oil (oil liquid) from being rapidly discharged from the hydraulic chamber 3A of the variable displacement actuator 3 to the tank port 4C side.

Then, the flow rate of the oil liquid discharged from the hydraulic chamber 3A of the variable capacity actuator 3 to the tank port 4C side so that the pressure generated between the fixed throttle 6 and the pressure reducing valve 7 becomes a substantially constant pressure. Can be effectively adjusted, the flow rate at this time can be kept substantially constant, and the tilting piston 3B of the variable displacement actuator 3 can be gradually moved in the direction of arrow A at a substantially constant speed. The displacement varying unit 2 of the motor 1 can be tilted and driven smoothly and stably from the small tilt side to the large tilt side.

Therefore, according to the present embodiment, the hydraulic motor 1
The capacity of can be smoothly and stably switched from a small capacity to a large capacity, and it is possible to effectively prevent a sudden change in pressure and flow rate in the hydraulic circuit. Then, for example, the traveling speed of the hydraulic excavator (of the vehicle) or the like can be changed smoothly, and the ride comfort and steering stability of the driver can be effectively improved.

Further, the pressure oil supply / discharge port 4A of the switching valve device 4
A capacity switching valve 5 is provided between the high pressure port 4B and the tank port 4C, and a flow control valve 8 including a fixed throttle 6 and a pressure reducing valve 7 is provided between the pressure oil supply / discharge port 4A and the tank port 4C. By providing it, the whole can be configured as a single valve device, and the switching valve device 4 can be compactly formed to be small in size and light in weight.

Next, FIG. 2 shows a second embodiment of the present invention. In this embodiment, the same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. To do. However, the feature of this embodiment is that the high pressure port 4 of the switching valve device 4 is
B is connected to the discharge side of the pilot pump 18 via the control line 31.

Here, the control line 31 is provided when the capacity switching valve 5 is switched from the switching position (a) to the switching position (b).
Pilot pump 18 whose pressure is set by relief valve 22
Is supplied to the hydraulic chamber 3A of the variable capacity actuator 3 through the high pressure port 4B of the switching valve device 4 and the pressure oil supply / discharge port 4A, and the tilting piston 3B of the variable capacity actuator 3 is moved in the direction of arrow B. Drive to.

Thus, in this embodiment having the above-mentioned structure, it is possible to obtain substantially the same effects as the first embodiment, but in this embodiment, the pressure is set by the relief valve 22. By supplying the pressure oil from the pilot pump 18 to the hydraulic chamber 3A of the variable displacement actuator 3 via the control conduit 31 or the like, the pressure oil of a stable pressure is supplied to the hydraulic chamber 3A of the variable displacement actuator 3. You can

Next, FIGS. 3 to 6 show a third embodiment of the present invention. The feature of this embodiment is that the capacity switching means for supplying and discharging pressure oil to the capacity variable actuator of the hydraulic pump is the first. , A hydraulic pilot type switching valve between the second switching positions, which is an intermediate position for shutting off the pressure oil supply / discharge port from the tank port and the high pressure port. The configuration is such that a switching control unit that switches the switching valve to the intermediate position according to the pressure generated in the pressure generation unit is provided when switching from the switching position of 1 to the first switching position. In this embodiment, the same components as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the figure, reference numeral 41 indicates a switching valve device as a capacity switching means for switching and controlling the pressure oil supplied to and discharged from the variable displacement actuator 3. The switching valve device 41 is connected to the hydraulic chamber 3A of the variable displacement actuator 3. Pressure oil supply / discharge port 41
A, a high pressure port 41B and a tank port 41C which are connected to the shuttle valve 16 via a control line 17. The switching valve device 41 includes the pressure oil supply / discharge port 41A.
And a high pressure port 41B and a tank port 41C, and is configured as a hydraulic pilot type switching valve 42, and a throttle passage 51 described later is provided between the pressure oil supply / discharge port 41A and the tank port 41C. .

Here, as shown in FIGS. 4 to 6, the switching valve 42 of the switching valve device 41 comprises a valve casing 43 and a spool 46, a piston 53 and the like which will be described later, and the valve casing 43 has a bottom. The spool sliding hole 44 is formed, and the tank port 41C, the pressure oil supply / discharge port 41A, the high pressure port 41B, and the pilot port 41D are formed so as to be separated from each other in the axial direction of the spool sliding hole 44. The valve casing 43 is connected to the tank port 4
1C is connected to the tank 10 as shown in FIG. 3, and the pressure oil supply / discharge port 41A is connected to the hydraulic chamber 3 of the variable capacity actuator 3.
It is connected to A. Further, the high pressure port 41B is connected to the shuttle valve 16 via the control line 17, and the pilot port 41D is connected to the pilot line 20.

Reference numeral 45 designates a lid body which covers the tip end side opening of the spool sliding hole 44 and constitutes a part of the valve casing 43. The lid body 45, as shown in FIGS. A pilot oil chamber 52, which will be described later, is formed between and.

Reference numeral 46 denotes a spool inserted into the spool sliding hole 44 of the valve casing 43. The spool 46 is formed in a bottomed cylindrical shape with one end side having a bottom portion 46A, and the inner peripheral side has a piston sliding hole. It is 46B. Further, on the outer peripheral side of the spool 46, an annular groove 46C as a first passage that communicates and blocks the pressure oil supply / discharge port 41A with the high pressure port 41B, and is separated from the annular groove 46C in the axial direction, The pressure oil supply / discharge port 41A communicates with the tank port 41C,
An annular groove 46D is formed as a second passage for blocking. The annular groove 46D is formed in the radial communication passage 46.
E and a control pressure chamber 54, which will be described later, and a stepped hole 50, etc., are always connected to the tank port 41C.

Reference numeral 47 denotes a spring chamber formed between the bottom portion 46A of the spool 46 and the valve casing 43, and the spring chamber 47 is in constant communication with the tank port 41C. Also,
A cylindrical stopper 48 is arranged in the spring chamber 47,
The stopper 48 regulates the maximum stroke position of the spool 46 as shown in FIG. 5 when the switching valve 42 switches from the first switching position (e) shown in FIG. 3 to the second switching position (f). Is.

Reference numeral 49 denotes a pressure setting spring disposed in the spring chamber 47. The spring 49 has a spring force of about Pb as in the spring 5A described in the first embodiment and has a spool. By constantly urging the valve 46 toward the pilot oil chamber 52 side to the initial position shown in FIG.
2 is returned to the first switching position (e) shown in FIG.

Reference numeral 50 denotes a stepped hole formed in the bottom portion 46A of the spool 46. The stepped hole 50 allows the control pressure chamber 54 to communicate with the spring chamber 47 at all times, and the stepped hole 50 has a small diameter side. It is a small-diameter throttle passage 51 that constitutes a pressure generating portion. When the pressure oil (oil liquid) flows from the control pressure chamber 54 toward the spring chamber 47, the throttle passage 51 generates a pressure in the control pressure chamber 54 by giving a throttle action to the oil liquid. It is configured to let.

Reference numeral 52 denotes a pilot oil chamber as a hydraulic pilot portion formed between the other end side of the spool 46 and the lid 45. The pilot oil chamber 52 is connected to the pilot conduit 20 via the pilot port 41D. When the capacity selection valve 19 shown in FIG. 3 is connected and switched to the small capacity position (d), the pilot pressure of the pressure Pa (Pa> Pb) set by the pressure reducing valve 21 is piloted via the pilot conduit 20. By being supplied into the oil chamber 52, the spool 46 is slidably displaced toward the spring chamber 47 side against the spring 49 as shown in FIG. 5, and the switching valve 42 is switched from the switching position (e) shown in FIG. Switch to position (f).

53 is a piston sliding hole 46 of the spool 46.
A piston inserted in B is shown. One end of the piston 53 forms a control pressure chamber 54 as a switching control unit between the piston 53 and the piston sliding hole 46B. And relatively displace the spool 46 as shown in FIG.
The switching valve 42 is switched to the intermediate position (g) shown in FIG. When the switching valve 42 reaches the intermediate position (g), the pressure oil supply / discharge port 41A is shut off from the tank port 41C and the high pressure port 41B. Further, the other end of the piston 53 becomes a large-diameter head portion 53A protruding into the pilot oil chamber 52.
Is configured so as to come into contact with the end surface of the lid 45 and the end surface of the spool 46 so as to be separated from and in contact with each other.

The hydraulic motor displacement control device according to the present embodiment has the above-mentioned structure, and the basic operation thereof is not different from that according to the first embodiment.

However, according to the present embodiment, the hydraulic pump 1
The switching valve device 41 for supplying / discharging pressure oil to / from the variable capacity actuator 3 is provided with the pressure oil supply / discharge port 41A between the first and second switching positions (e) and (f) to the tank port 41C and the high pressure port 41B. The switching valve 4 is constituted by a hydraulic pilot type switching valve 42 which is in an intermediate position (g) for shutting off the switching valve 4.
In the second spool 46, when the second switching position (f) is switched to the first switching position (e), the throttle passage 51
Since the control pressure chamber 54 that switches the switching valve 42 to the intermediate position (g) is provided in accordance with the pressure generated in step 1, the following operational effects can be obtained. .

That is, when the switching valve 42 is switched from the switching position (f) to the switching position (e) in order to switch the capacity of the hydraulic motor 1 from the small capacity to the large capacity, the spool 46 is moved.
While returning from the maximum stroke position shown in FIG. 5 to the initial position shown in FIG. 4, the pressure oil (oil liquid) in the hydraulic chamber 3A of the variable displacement actuator 3 has pressure oil supply / discharge port 41A and control pressure chamber 54, etc. Through the spring chamber 47 (tank port 41
By flowing to the C) side, the piston 53 and the spool 4
A pressure can be generated in the control pressure chamber 54 between 6 and 6 in the throttle passage 51.

The pressure in the control pressure chamber 54 acts on the bottom portion 46A side of the spool 46 and the end surface of the piston 53 to press the piston 53 and the spool 46 in opposite directions to each other, and When the head portion 53A comes into contact with the end surface of the lid body 45 as shown in FIG. 6, the spool 46 can be slid and displaced toward the spring chamber 47 side against the spring 49, whereby the switching valve 42 is shown in FIG. It is possible to temporarily switch to the intermediate position (g).

At this intermediate position (g), the pressure oil supply / discharge port 41A is located at the high pressure port 41B and the tank port 41.
Since both are blocked by C, the pressure oil (oil liquid) in the hydraulic chamber 3A of the variable displacement actuator 3 does not flow into the control pressure chamber 54 via the pressure oil supply / discharge port 41A.
The spool 46 is biased toward the pilot oil chamber 52 side by the spring 49, so that the oil liquid in the control pressure chamber 54 is released from the spring chamber 47.
Is gradually discharged to the side through the throttle passage 51, and the spool 4
6 is slidably displaced to a position where the annular groove 46D communicates with the pressure oil supply / discharge port 41A.

Then, the oil liquid in the hydraulic chamber 3A of the variable displacement actuator 3 is supplied again into the control pressure chamber 54 via the pressure oil supply / discharge port 41A.
As the pressure is generated in the throttle passage 51, the spool 46 can again be slid to the intermediate position shown in FIG. 6 against the spring 49.

As a result, the spool 46 slides in the annular groove 46D so that the pressure oil supply / discharge port 41A and the tank port 41C are repeatedly connected and disconnected as the pressure in the control pressure chamber 54 increases or decreases. The flow rate of the oil liquid (exhaust oil) that is dynamically displaced and discharged from the hydraulic chamber 3A of the variable displacement actuator 3 to the tank port 41C side via the pressure oil supply / discharge port 41A can be limited to a substantially constant flow rate. .

Thus, also in this embodiment having such a configuration, it is possible to effectively prevent the oil liquid from being rapidly discharged from the hydraulic chamber 3A of the variable displacement actuator 3 to the tank port 41C side, and the first embodiment described above is provided. As in the embodiment, the capacity of the hydraulic motor 1 can be smoothly and stably switched from a small capacity to a large capacity, and it is possible to effectively prevent a sudden change in pressure or flow rate in the hydraulic circuit.

Further, particularly in this embodiment, the switching valve device 41
Is constituted by a hydraulic pilot type switching valve 42, and a throttle passage 51 as a pressure generating portion and a control pressure chamber 54 as a switching control portion are formed in the spool 46 of the switching valve 42. Can be configured as a single valve device, and the switching valve device 41 can be made compact as a whole to further reduce the size and weight.

In the third embodiment, the high pressure port 41B of the switching valve device 41 is described as being connected to the shuttle valve 16 via the control line 17, but instead of this, it is shown in FIG. Similarly to the second embodiment, the switching valve device 4
The first high pressure port 41B may be connected to the discharge side of the pilot pump 18 via the control line 31.

In each of the above embodiments, the case where the displacement control device for the hydraulic rotary machine is applied to the traveling hydraulic motor of the hydraulic excavator and the traveling hydraulic circuit has been described as an example. However, the hydraulic motor 1 may be a turning hydraulic motor, and may be applied to various construction machines such as a hydraulic crane in addition to the hydraulic excavator. And
The hydraulic rotating machine is not limited to a hydraulic motor, and may be applied to a hydraulic pump.

[0076]

As described in detail above, according to the first aspect of the present invention, when the tank port and the pressure oil supply / discharge port communicate with each other between the pressure oil supply / discharge port and the tank port of the capacity switching means. , A pressure generating portion for generating a pressure in the oil liquid discharged from the pressure oil supply / discharge port to the tank port side, and a flow depending on the pressure generated at the pressure generating portion located upstream of the pressure generating portion. Since a flow control valve consisting of a variable throttle that changes the passage area is provided, pressure is generated when the pressure oil supply / discharge port of the capacity switching means is connected to the tank port in order to switch the capacity of the hydraulic rotary machine. Part can generate pressure in the oil liquid discharged from the pressure oil supply / discharge port to the tank port side, and can change the flow passage area of the variable throttle part according to the pressure generated in the pressure generating part. , The flow rate of discharged oil is almost constant It can control. Therefore, it is possible to smoothly stabilize and switch the capacity of the hydraulic rotary machine, and it is possible to effectively prevent a sudden change in the pressure and flow rate in the hydraulic circuit, and to smoothly change the traveling speed, for example. Therefore, the ride comfort of the driver can be surely improved.

Further, in the invention described in claim 2,
The hydraulic pilot type switching valve between the second switching positions is an intermediate position that shuts off the pressure oil supply / discharge port with respect to the tank port and the high pressure port to form the capacity switching means. When the switching position is switched to the first switching position, the switching control unit is provided for switching the switching valve to the intermediate position according to the pressure generated in the pressure generating unit. And the intermediate position can be switched repeatedly, and the flow rate of the oil liquid (discharge oil) discharged from the variable volume actuator to the tank port via the pressure oil supply / discharge port can be limited to a substantially constant value. The capacity of the rotating machine can be changed smoothly and stably.

In this case, as in the third aspect of the present invention, the changeover valve is constituted by the valve casing, the spool, the spring, the hydraulic pilot portion and the piston, so that the changeover valve is moved from the second changeover position to the first changeover position. When switching to the switching position of 1, the pressure from the pressure generating section can be applied to the switching control section formed between the one end side of the piston and the spool, and the pressure at this time causes the spool to resist the spring. It is possible to slide the displacement to temporarily switch to the intermediate position, and also to stop the discharge of the oil liquid in the variable volume actuator to the tank port side, limiting the flow rate at this time to a substantially constant value. The capacity of the hydraulic rotary machine can be changed smoothly and stably.

According to the invention described in claim 4, the spool is provided with the first passage, the second passage, the small-diameter throttle passage constituting the pressure generating portion, and the second passage as the switching control portion. By providing the communication passage that always communicates with the second control device, the second control device can be used as the pressure in the switching control unit increases or decreases.
The spool can be slidably displaced so that the pressure oil supply / discharge port and the tank port are repeatedly communicated and blocked in the passage, and the flow rate of the oil liquid discharged from the variable capacity actuator to the tank port side can be effectively controlled. In addition, the entire switching valve can be made compact, and various effects can be achieved such as reduction in size and weight.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram showing a displacement control device for a traveling hydraulic motor according to a first embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram showing a displacement control device for a traveling hydraulic motor according to a second embodiment of the present invention.

FIG. 3 is a hydraulic circuit diagram showing a displacement control device for a traveling hydraulic motor according to a third embodiment of the present invention.

FIG. 4 is a vertical cross-sectional view of a spool, a piston and the like showing a state in which the switching valve device in FIG. 3 is switched to a first switching position.

5 is a longitudinal sectional view of a spool, a piston and the like showing a state in which the switching valve device in FIG. 3 is switched to a second switching position.

6 is a longitudinal sectional view of a spool, a piston and the like showing a state in which the switching valve device in FIG. 3 is switched to an intermediate position.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hydraulic motor (hydraulic pressure rotary machine) 2 Capacity variable part 3 Capacity variable actuator 4,41 Switching valve device (capacity switching means) 4A, 41A Pressure oil supply / discharge port 4B, 41B High pressure port 4C, 41C Tank port 5 Capacity switching valve 5A, 49 springs 5B hydraulic pilot section 6 fixed throttle (pressure generating section) 7 pressure reducing valve (variable throttle section) 8 flow control valve 9 hydraulic pump (main hydraulic pressure source) 10 tank 11A, 11B main pipeline 12 control valve 16 shuttle valve ( High pressure selection valve) 17,31 Control line 18 Pilot pump (Pilot hydraulic power source) 19 Capacity selection valve 20 Pilot line 41D Pilot port 42 Switching valve 43 Valve casing 44 Spool sliding hole 46 Spool 46B Piston sliding hole 46C Annular groove (First passage) 46D Annular groove (Second passage) 46E Communication passage 47 Spring 51 throttle passage (pressure generating portion) 52 pilot oil chamber (hydraulic pilot portion) 53 piston 54 the control pressure chamber (switching control unit)

Claims (4)

[Claims] 1. A variable displacement type hydraulic rotary machine having a variable capacity section, and a capacity variable section of the hydraulic rotary machine is driven by supplying and discharging pressure oil to reduce the capacity of the hydraulic rotary machine. A variable capacity actuator for switching between a large capacity and a large capacity, and a pressure oil supply / discharge port, a high pressure port and a tank port connected to the variable capacity actuator are provided, and the pressure oil supply / discharge port is selectively used as a high pressure port and a tank port. And a capacity switching means for supplying and discharging pressure oil from the high pressure port to the variable capacity actuator via the pressure oil supply and discharge port by communicating with the high pressure port. Between the pressure oil supply / discharge port and the tank port, a pressure is generated in the oil liquid discharged from the pressure oil supply / discharge port to the tank port side when the tank port and the pressure oil supply / discharge port communicate with each other. Pressure generation And a variable throttle section located upstream of the pressure generating section and changing the flow passage area according to the pressure generated in the pressure generating section. Capacity control device. 2. A variable displacement hydraulic rotary machine having a variable capacity section, and a capacity variable section of the hydraulic rotary machine is driven by supplying and discharging pressure oil to reduce the capacity of the hydraulic rotary machine. A variable capacity actuator for switching between a large capacity and a large capacity, and a pressure oil supply / discharge port, a high pressure port and a tank port connected to the variable capacity actuator are provided, and the pressure oil supply / discharge port is selectively used as a high pressure port and a tank port. And a capacity switching means for supplying and discharging pressure oil from the high pressure port to the variable capacity actuator via the pressure oil supply and discharge port by communicating with the high pressure port. Is a first switching position that is switched by a spring to connect the pressure oil supply / discharge port to the tank port, and is switched by a pilot pressure against the spring to change the pressure oil supply / discharge port to a high pressure port. Hydraulic pressure having a second switching position for communication and an intermediate position located between the second switching position and the first switching position for blocking the pressure oil supply / discharge port from the tank port and the high pressure port. A pilot type switching valve is provided between the pressure oil supply / discharge port and the tank port when the switching valve switches from the second switching position to the first switching position. A pressure generating portion for generating a pressure in the oil liquid discharged from the discharge port to the tank port side, and the switching valve located at an upstream side of the pressure generating portion and having the switching valve at an intermediate position according to the pressure generated in the pressure generating portion. A capacity control device for a hydraulic rotating machine, comprising: 3. The switching valve includes a valve casing having the pressure oil supply / discharge port, a high pressure port, a tank port and a pilot port formed therein, and the pressure oil supply / discharge port slidably fitted in the valve casing. A spool that selectively connects and disconnects the port with respect to the high-pressure port and the tank port, a spring chamber that is formed between one end of the spool and the valve casing, and that is constantly in communication with the tank port, and a spring chamber within the spring chamber. A spring that is disposed and constantly urges the spool in the axial direction and a spring that is located at the other end side of the spool and is formed in the valve casing and is supplied with pilot pressure from the pilot port The hydraulic pilot portion for slidingly displacing the spool, and the one end side which is slidably fitted in the spool to form the switching control portion between the spool and the other end side. The displacement control device for a hydraulic rotating machine according to claim 2, wherein the displacement control device comprises a piston protruding into the hydraulic pilot portion. 4. A first passage for connecting and disconnecting the pressure oil supply / discharge port to and from the high pressure port in the spool,
A second passage, which is separated from the first passage and connects and disconnects the pressure oil supply / discharge port with respect to the tank port, is formed between the spring chamber and the switching control unit, and constitutes the pressure generation unit. The throttle passage having a small diameter, and a communication passage for constantly communicating the switching control unit and the second passage for guiding the oil liquid from the pressure oil supply / discharge port into the switching control unit are provided. Capacity control device for the hydraulic rotating machine described.