JPH11210634A - Capacity control device of liquid pressure rotary machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the forming process of a capacity change-over valve, as well as to prevent a sudden variation of the discharge pressure and the discharge flow rate of a hydraulic pump. SOLUTION: In a capacity control device of a liquid pressure rotary machine provided with a variable capacity type of liquid pressure rotary machine 1; a capacity variable actuator 3; and a capacity change-over valve 4 to feed and exhaust a pressure oil to the capacity variable actuator 3 by converting the first change-over position and the second change-over position selectively; the capacity change-over valve 4 is furnished with a small diameter throttle passage 43 formed inside a spool, and provided to penetrate the spool in the diameter direction; a first cutting provided at the outer periphery of the above spool, and communicates a high pressure port 41B and one end of the throttle passage 43 at the above second change-over position; and a second cutting provided at the outer periphery of the above spool, and communicates a pressure oil feed and exhaust port 41A, and the other end of the throttle passage 41A.

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, and more particularly to a hydraulic control device for a hydraulic excavator or other construction machine suitable for controlling the displacement of a hydraulic pump or a hydraulic motor. The present invention relates to a capacity control device for a pressure rotary machine.

[0002]

2. Description of the Related Art Conventionally, as a capacity control device for a hydraulic rotating machine, for example, Japanese Patent Publication No.
49175) are known. This is achieved by changing the pilot pressure supplied to the capacity switching valve by operating means, selectively connecting the pressure oil supply / discharge port of the capacity switching valve to the high pressure port and the tank port, and controlling the pressure supplied / discharged to the variable capacity actuator. The oil is switched and the variable capacity portion of the hydraulic rotary machine is tilted to switch the capacity of the hydraulic rotary machine between small capacity and large capacity.

When this hydraulic rotary machine is used, for example, as a hydraulic motor, when the load pressure is small, the motor capacity is switched to a small capacity so as to rotate at high speed with a small torque, and when the load pressure is large, By switching to a large capacity and rotating at a low speed with a large torque, a large increase in the load pressure is suppressed, and a load such as a hydraulic pump does not act on an overload.

When the displacement control device of the hydraulic rotary machine is applied to a hydraulic shovel, a driver or the like of the hydraulic shovel switches an operation means for switching the displacement, and the displacement is changed according to a pilot pressure from the operation means. The pressure oil supply / discharge port of the switching valve is selectively communicated with the high pressure port and the tank port,
If the motor capacity of the hydraulic motor is switched between the small capacity and the large capacity in two stages, the discharge pressure and the discharge flow rate of the hydraulic pump may suddenly change at the moment when the motor capacity is switched. If this is a hydraulic motor for driving, there is a problem that the driving speed changes suddenly at the time of switching and the ride comfort of the driver deteriorates, and the same problem occurs when the motor is used as a hydraulic pump.

Therefore, for example, Japanese Patent Application Laid-Open No. 7-30120
As disclosed in Japanese Patent Laid-Open Publication No. 5 (1993) -2005, etc., in such a capacity control device for a hydraulic rotary machine, the hydraulic oil supply / discharge port of the capacity switching valve is selectively communicated with a high pressure port and a tank port, and the motor of a hydraulic motor is When switching the capacity between two stages, small capacity and large capacity, it has been proposed to provide a throttle in the oil passage in the capacity switching valve in order to prevent a sudden change in the discharge pressure and the discharge flow rate of the hydraulic pump. I have.

[0006]

However, in the above prior art, the oil passage connecting the pressure oil supply / discharge port of the capacity switching valve to the high pressure port or the tank port slides between the valve case and the outer periphery of the spool. Since it is formed in the moving part, when the capacity switching valve is switched, the outer peripheral portion of the spool also serves as a throttle at the same time as the switching of the oil passage by sliding. Therefore, when creating the capacity switching valve,
The sliding outer peripheral surface must be designed and worked with both the switching function and the drawing function, and there is a problem in the production.

[0007] The object of the present invention, in view of the above problems,
When the hydraulic oil supply / discharge port of the displacement switching valve is selectively communicated with the high pressure port and the tank port to switch the motor capacity of the hydraulic motor between two stages, a small capacity and a large capacity, the discharge pressure and the discharge flow rate of the hydraulic pump are changed. An object of the present invention is to provide a displacement control device for a hydraulic rotary machine that prevents a sudden change and facilitates processing for producing a displacement switching valve.

[0008]

The present invention has the following features to attain the object mentioned above.

A variable capacity hydraulic rotary machine having a variable capacity section, and a capacity for driving the variable capacity section by supplying and discharging pressure oil to switch the capacity of the hydraulic rotary machine to a small capacity or a large capacity. Selectable between a variable actuator, a first switching position for connecting a pressure oil supply / discharge port connected to the variable capacity actuator to a tank port, and a second switching position for connecting the pressure oil supply / discharge port to a high pressure port. And a capacity switching valve for supplying and discharging the pressure oil of the variable capacity actuator, wherein the capacity switching valve includes the pressure oil supply / discharge port and the high pressure port. A valve casing in which the tank port and the pilot port are formed, and the pressure oil supply / discharge port slidably fitted in the valve casing to select a high-pressure port or a tank port. , A spring chamber formed between one end of the spool and the valve casing and always communicating with the tank port, and disposed in the spring chamber to constantly bias the spool in the axial direction. A spring, and a hydraulic pilot portion formed in the valve casing at the other end of the spool and supplied with pilot pressure from the pilot port to slide and displace the spool against the spring. A small-diameter throttle passage formed inside the spool and radially penetrating the spool; and a small-diameter throttle passage provided on the outer periphery of the spool when the high-pressure port and the throttle passage are in the second switching position. A first notch communicating with one end of the pressure oil supply / discharge port and the throttle passage provided at an outer periphery of the spool at the second switching position; The communicating 2
And a notch.

[0010] In the capacity control device for a hydraulic rotary machine according to claim 1, the throttle passage is provided so as to penetrate in a direction substantially perpendicular to a sliding displacement direction of the spool.
It is characterized in that it is provided at a position between the pressure oil supply / discharge port and the high pressure port at the time of the second switching position.

Further, in the capacity control apparatus for a hydraulic rotary machine according to any one of claims 1 and 2, the spool is configured to connect or disconnect the pressure oil supply / discharge port with a tank port. It has a passage, and the small-diameter throttle passage is provided so as to communicate the communication passage and the spring chamber.

A variable displacement type hydraulic rotating machine having a variable capacity portion, and a hydraulic displacement device driven by supplying and discharging pressure oil to reduce the capacity of the hydraulic rotating device to a small capacity or a large capacity. A plurality of variable capacity actuators to be switched, and a pressure oil supply / discharge port connected to one of the variable capacity actuators is connected to a tank port, and a pressure oil supply / discharge port connected to the other variable capacity actuator is connected to a high pressure port. A first switching position to be communicated, and a pressure oil supply / discharge port connected to the one variable capacity actuator are connected to a high pressure port, and a pressure oil supply / discharge port connected to the other variable capacity actuator is connected to a tank port. And selectively switching to a second switching position to communicate with
A capacity switching valve for supplying and discharging the pressure oil of each of the variable capacity actuators, wherein the capacity switching valve includes the pressure oil supply / discharge port, the high pressure port, and the tank. A valve casing having a port and a pilot port formed therein, a spool slidably fitted into the valve casing to selectively communicate or shut off each of the pressure oil supply / discharge ports with a high pressure port or a tank port;
A spring chamber formed between one end of the spool and the valve casing and always communicating with the tank port; a spring disposed in the spring chamber and constantly biasing the spool in the axial direction;
A hydraulic pilot portion formed at the other end of the spool and formed in the valve casing and supplied with pilot pressure from the pilot port to slide and displace the spool against the spring; A plurality of small-diameter throttle passages formed inside the spool and radially penetrating the spool, and the high-pressure port and one of the throttle passages provided at an outer periphery of the spool at the second switching position A first cutout communicating one end of the pressure oil supply / discharge port and the one throttle passage provided on the outer periphery of the spool and connected to the one variable displacement actuator at the second switching position. And a second notch communicating with the other end of the variable displacement actuator, which is provided on the outer periphery of the spool and is connected to the other variable capacity actuator at the second switching position. A third notch communicating the pressure oil supply / discharge port with one end of the other throttle passage; and a third notch provided on the outer periphery of the spool when the tank is in the second switching position. And a fourth notch communicating the end.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 shows a hydraulic circuit of a displacement control device for a hydraulic rotary machine according to this embodiment.

In FIG. 1, reference numeral 1 denotes a variable displacement type hydraulic motor which constitutes a traveling hydraulic motor, and has a displacement variable section 2 composed of a swash plate or a valve plate. The variable capacity section 2 is controlled by a variable capacity actuator 3 described later by an arrow A.
Alternatively, when the tilting drive is performed in the B direction and the tilt angle is maximized by rotating in the A direction, the motor capacity of the hydraulic motor 1 is increased, and the tilt angle is minimized by rotating in the B direction. In such a case, the motor capacity is set to a small capacity. Reference numeral 3 denotes a variable displacement actuator attached to the hydraulic motor 1 and has a tilt piston 3B defining a hydraulic chamber 3A, and the tilt piston 3B is driven by an arrow A or an arrow A according to pressure oil supplied and discharged into the hydraulic chamber 3A. Driven in the direction B, the variable displacement section 2 of the hydraulic motor 1 is tilted to the maximum tilt side and the minimum tilt side.

Reference numeral 4 denotes a capacity switching valve for controlling switching between pressure oil supplied and discharged to the variable capacity actuator 3, which is a pressure oil supply / discharge port 41A connected to a hydraulic chamber 3A of the variable capacity actuator 3, and a shuttle valve described later. It has a high-pressure port 41B connected to the tank 13 via the control line 14, a tank port 41C connected to the tank 7, and a pilot port 41D.

Reference numeral 42 denotes a spring which constantly biases a spool described later toward the pilot port 41D in the axial direction; 43, a first throttle passage communicating between the high pressure port 41B and the pressure oil supply / discharge port 41A; The second throttle passage communicates between the supply / discharge port 41A and the tank port 41C.

Reference numeral 6 denotes a hydraulic pump which constitutes a main hydraulic power source together with the tank 7, is driven to rotate by a motor (not shown), and discharges hydraulic oil sucked from the tank 7 as high-pressure oil. The hydraulic pump 6 and the tank 7 are connected to the hydraulic motor 1 via main pipelines 8A and 8B.

Reference numeral 9 denotes a traveling control valve provided in the middle of the main pipelines 8A and 8B. The traveling control valve 9 is switched from the neutral position (a) to the switching position (b) or (c) by the operating lever 9A, and is switched to the switching position ( In (b) or (c), the direction of the pressure oil supplied and discharged from the hydraulic pump 6 to the hydraulic motor 1 is switched. As the control valve 9, a normally open type directional control valve is adopted, and in the neutral position (a), the main pipeline 8A or 8B
When the internal pressure becomes negative, hydraulic fluid in the tank 7 is supplied to the main pipeline 8A or 8B. 10A, 1
A pair of check valves 11B is provided between the hydraulic motor 1 and the control valve 9 and provided in the middle of the main pipelines 8A and 8B.
Is located in parallel with the check valves 10A and 10B and
A counterbalance valve provided in the middle of A and 8B, which is switched almost in conjunction with the control valve 9 by a differential pressure between the main pipelines 8A and 8B, and is closed when the hydraulic motor 1 is rotated by inertia or the like. And the main pipeline 8A before and after the hydraulic motor 1
Alternatively, a brake pressure is generated within 8B.

A pair of overload relief valves 12A and 12B are provided between the hydraulic motor 1 and the counterbalance valve 11 and provided in the middle of the main pipelines 8A and 8B. The overload relief valves 12A and 12B are hydraulic motors. When the brake pressure rises to a predetermined set pressure, for example, when the engine 1 is stopped, the valve is opened, and the excessive pressure at this time is released to prevent the excessive pressure from acting on the hydraulic motor 1 and the like.

Reference numeral 13 denotes a shuttle valve which is located between the hydraulic motor 1 and the counterbalance valve 11 and acts as a high-pressure selection valve provided between the main lines 8A and 8B.
The hydraulic oil on the high pressure side is selected from A and 8B, and this hydraulic oil is supplied to the hydraulic chamber 3A of the variable capacity actuator 3 via the control line 14 and the capacity switching valve 5.

Reference numeral 15 denotes a pilot pump which constitutes a pilot hydraulic source together with the tank 7, and 16 denotes a pilot pump.
5 is a capacity selection valve for switchingly connecting the tank 5 and the tank 7 to the pilot pipe line 17, and includes an operation lever 16 </ b> A for switching the motor capacity of the hydraulic motor 1. When the driver tilts the operation lever 16A, the large capacity position (c) and the small capacity position (d) of the capacity selection valve 16 are selectively switched.

Reference numeral 19 denotes a pressure reducing valve provided between the pilot pump 15 and the capacity selection valve 16.
Is switched to the small capacity position (d), the pilot pressure supplied from the pilot pump 15 to the pilot line 17 is reduced to a pressure Pa lower than the set pressure of the relief valve 18.
The pressure is reduced to Here, assuming that the switching set pressure by the spring 42 of the capacity switching valve 4 is Pb, the pressure Pa set by the pressure reducing valve 18 has a relationship of Pa> Pb, and the switching set pressure of the capacity switching valve 4 (pressure Pb). Set to a higher pressure.

Next, the details of the capacity switching valve 4 will be described with reference to FIGS.
This will be described with reference to FIG.

FIG. 2 is a sectional view of the capacity switching valve 4 when the pressure oil supply / discharge port 41A is connected to the tank port 41C, and FIG. 3 is a capacity when the pressure oil supply / discharge port 41A is connected to the high pressure port 41B. FIG. 4 is a cross-sectional view of the capacity switching valve 4 as viewed from the line A in FIG. 3, and FIG. 5 is a cross-sectional view of the capacity switching valve 4 as viewed from the roll in FIG.

In these figures, the switching valve 4 comprises a valve casing 45 and a spool 47 which will be described later. The valve casing 45 has a bottomed spool sliding hole 46 and a spool sliding hole 46. A tank port 41C, a pressure oil supply / discharge port 41A, a high pressure port 41B, and a pilot port 41D are formed apart from each other in the axial direction.

Numeral 47 denotes a spool which is inserted into a spool sliding hole 46 of the valve casing 43, and has a bottomed cylindrical shape at one end. A small-diameter first throttle passage 43 is provided inside the spool 47, and a first notch 52 for communicating or blocking the high-pressure port 41 </ b> B and the first throttle passage 43 is provided on the outer periphery of the spool 47, Pressure oil supply / discharge port 41A
Notch 53 communicating with or blocking the first throttle passage 43 and the first and second notches 52 and 53 are axially separated from each other so that the pressure oil supply / discharge port 41A is connected to the tank port 41C.
Annular groove 51 as a communication passage communicating or blocking the
Are formed. The annular groove 51 is configured to always communicate with the tank port 41C via the second throttle passage 44 and the communication hole 50. Reference numeral 48 denotes a spring chamber formed between the bottom of the spool 47 and the valve casing 45. The spring chamber 48 is always in communication with the tank port 41C. Further, a cylindrical stopper 49 is disposed in the spring chamber 48, and the capacity switching valve 4 is moved from the first switching position shown in FIG.
The maximum stroke position of the spool 47 is regulated when switching to the second switching position shown in FIG.

Reference numeral 42 denotes a pressure setting spring disposed in the spring chamber 48. The spring 42 has a spring force of about the pressure Pb, and moves the spool 47 toward the pilot oil chamber 54 to the initial position. It is always urged in the axial direction, and returns the capacity switching valve 4 to the first switching position shown in FIG. First
The throttle passage 43 is a small-diameter throttle passage provided inside the spool 47 so as to penetrate in the radial direction substantially perpendicular to the axial direction, and includes a first cutout 52 and a second cutout provided on the outer peripheral side of the spool 47. The notch 53 is configured to communicate the high pressure port 41B and the pressure oil supply / discharge port 41A via the first throttle passage 43. When the pressure oil flows from the high pressure port 41B to the pressure oil supply / discharge port 41A, the first throttle passage 43 exerts a throttle action on the pressure oil,
The pressure oil flow is controlled (restricted).

As shown in FIG. 4 and FIG.
The second cutouts 52 and 53 are provided on the outer peripheral side of the spool 46 and are formed by grooves extending in the axial direction at positions circumferentially separated from each other by 180 degrees. When switching from the first switching position to the second switching position, the first notch 52 communicates with the high pressure port 41B and the first throttle passage 43, and the second notch 53 communicates with the pressure oil supply / discharge port 41A. And the first throttle passage 43. Reference numeral 50 denotes a communication hole formed in the bottom of the spool 47, which is configured to always communicate the tank port 41C and the annular groove 51 via the second throttle passage 44.
The second throttle passage 44 controls (restricts) the flow rate of the pressure oil by applying a throttle action to the pressure oil when the pressure oil flows from the pressure oil supply / discharge port 41A to the tank port 41C.
doing. Reference numeral 54 denotes a pilot oil chamber as a hydraulic pilot portion formed between the other end of the spool 47 and the valve casing 45, and is connected to the pilot line 17 via a pilot port 41D. When the capacity selection valve 16 is switched to the small capacity position (d), the pilot pressure of the pressure Pa (Pa> Pb) set by the pressure reducing valve 18 is supplied to the pilot oil chamber 54 via the pilot line 17. Thus, the spool 47 is slidably displaced toward the spring chamber 48 against the spring 42, and the capacity switching valve 4 is switched from the first switching position to the second switching position.

The capacity switching valve 4 connects the high pressure port 41B to the pressure oil supply / discharge port 41A at the second switching position, thereby supplying the pressure oil from the shuttle valve 13 to the hydraulic chamber 3A of the variable capacity actuator 3, Variable capacity actuator 3
Is driven in the B direction.

When the displacement switching valve 4 is switched to the first switching position by the spring 42, the pressure oil supply / discharge port 41A is communicated with the tank port 41C, so that the displacement from the hydraulic chamber 3A of the displacement variable actuator 3 is established. The pressure oil is discharged to the tank port 41C through the pressure oil supply / discharge port 41A, and the tilt piston 3B of the variable capacity actuator 3 is driven in the direction A.

Next, the operation of the displacement control device for a hydraulic rotary machine according to this embodiment will be described.

First, in FIG. 1, when the capacity selection valve 16 is switched to the large capacity position (c), the pilot line 17 is connected to the tank 7 and the tank pressure is attained. As shown in FIG. 2, the capacity switching valve 4 connects the pressure oil supply / discharge port 41A to the tank port 41C, and the pressure change supply valve 4 switches from the hydraulic chamber 3A of the variable capacity actuator 3 to the pressure oil supply / discharge port. 41A
The pressure oil is discharged to the tank port 41C side through the
Is driven in the direction of arrow A to set the motor capacity of the hydraulic motor 1 to a large capacity state. In this state, when the control valve 9 is switched from the neutral position (a) to the switching position (b) or (c) and the hydraulic oil is supplied from the hydraulic pump 6 to the hydraulic motor 1, the hydraulic pressure at this time causes the hydraulic motor 1 to operate. It can be driven to rotate with high torque, and the hydraulic excavator can run at low speed. In this case, the motor capacity is large and the load pressure of the hydraulic motor 1 can be prevented from greatly increasing, so that the discharge pressure of the hydraulic pump 6 and the like can be prevented from becoming excessively high, and the overload of the prime mover can be prevented. And smooth running up a hill or the like can be performed.

Next, in FIG. 1, when the capacity selection valve 16 is switched to the small capacity position (d), the pilot pressure of the pressure Pa set by the pressure reducing valve 18 is applied via the pilot pipe 17 to the capacity switching valve 4. Is switched from the switching position (a) to the switching position (b) against the spring 42. As a result, as shown in FIGS. 3 to 5, in the capacity switching valve 4, the high pressure port 41 </ b> B communicates with the pressure oil supply / discharge port 41 </ b> A, and the pressure oil from the shuttle valve 13 passes through the control line 14 to change the capacity 3 is supplied to the hydraulic chamber 3A, and the variable displacement actuator 3 is moved by the tilt piston 3B.
Is tilted in the direction of arrow B to the small tilting side, and the hydraulic motor 1 is started.
Set the motor capacity to a small capacity state.

Here, the high pressure port 41B has a first notch 52, a first throttle passage 43, and a second notch 53.
Through the pressure oil supply / discharge port 41A, the pressure oil from the high pressure port 41B is controlled (limited) by the first throttle passage 43 while the flow rate of the pressure oil is controlled by the pressure oil supply / discharge port 4A.
1A, it is possible to reliably prevent the pressure oil from the shuttle valve 13 from being rapidly supplied to the hydraulic chamber 3A of the variable capacity actuator 3. As a result, the displacement variable section 2 of the hydraulic motor 1 can be smoothly and stably tilted from the large tilt side, and the driving speed of the vehicle does not suddenly change. Can be prevented.

The hydraulic motor 1 is rotated at a high speed with a low torque by supplying and discharging the pressure oil from the hydraulic pump 6, so that the hydraulic shovel can run at a high speed. In this case, the hydraulic motor 1 has a small motor capacity, and the hydraulic motor 1 can rotate at high speed with a low torque in accordance with the flow rate of the pressure oil supplied / discharged via the control valve 9.
The vehicle can be driven on the road at a high speed, for example, when driving on level ground with a small load pressure acting on the vehicle.

Also, as shown in FIG.
Is switched from the small capacity position (d) to the large capacity position (c), the capacity switching valve 4 is switched to the switching position (a) by the spring 42, and the pressure oil supply / discharge port 41A communicates with the tank port 4C. Pressure oil is rapidly discharged from the hydraulic chamber 3A of the variable displacement actuator 3 to the tank port 41C through the pressure oil supply / discharge port 41A. In this case, FIG.
As shown in FIG. 7, the pressure oil supply / discharge port 41A communicates with the tank port 41C via the second throttle passage 44, and the flow rate of the pressure oil from the pressure oil supply / discharge port 41A is reduced by the second throttle passage 44. The tank port 41 is controlled (restricted).
Since the exhaust gas is discharged to C, it is possible to prevent a sudden change in the tilt angle of the variable displacement unit 2 and to smoothly and stably drive the variable displacement unit 2 of the hydraulic motor 1 from the small tilt side. In addition, it is possible to prevent the driver from vibrating or impacting due to a sudden change in the traveling speed of the vehicle.

As described above, according to the present embodiment, the capacity of the hydraulic motor can be smoothly and stably switched from the small capacity to the large capacity and from the large capacity to the small capacity. A rapid change in the flow rate can be effectively prevented. Therefore, for example, the traveling speed of the excavator can be changed smoothly, and the ride comfort and maneuverability of the driver can be improved.

Further, since the two throttle passages 43 and 44 are separately provided, the switching speed can be arbitrarily changed depending on the capacity switching direction by changing the opening area of each of the throttle passages 43 and 44.

The throttle passages 43 and 44 are provided with the capacity switching valve 4.
Since the devices are collectively provided, the device can be configured compactly without complicating the device, which contributes to downsizing of the device.

Further, the first throttle passage 43 is provided so as to penetrate in a direction substantially perpendicular to the sliding displacement direction of the spool 47, and at the time of the second switching position, the pressure oil supply / discharge port 41A.
And the high-pressure port 41B, the first throttle passage 43 may be formed so as to penetrate the spool 47 at the shortest distance. The spool 47 can be shortened in the axial direction, and the entire apparatus can be made compact. In addition, machining of the drawing passage can be easily performed.

Further, since the throttle passages 43 and 44 are small-diameter throttles, the moving speed of the tilting piston 3B of the variable displacement actuator 3 can be reduced to a machine difference due to a machining error or the like.

Further, since the aperture passages 43 and 44 are provided so as to penetrate in a direction substantially perpendicular to the sliding displacement direction, there is no need to provide the aperture passage with a switching function, and the switching function and the aperture function are made independent. And the processing of the capacity switching valve is facilitated.

Next, a second embodiment of the present invention will be described with reference to FIGS.

In the following description, FIGS.
In the configuration shown in FIG. 0, the same parts as those in the first embodiment shown in FIGS. 1 to 5 are denoted by the same reference numerals, and description thereof is omitted.

FIG. 6 shows a hydraulic circuit of the displacement control device of the hydraulic rotary machine according to the present embodiment.

In this figure, the variable displacement unit 2 is tilted and driven in the direction of arrow A or B by the variable capacity actuators 3 and 5, and when the tilt angle is maximized by rotating in the direction A, the displacement of the hydraulic motor 1 is reduced. The motor capacity is set to a large capacity. When the tilt angle is minimized by rotating in the direction B, the motor capacity is set to a small capacity. Reference numeral 5 denotes a variable displacement actuator attached to the hydraulic motor 1 and has a tilt piston 5B defining a hydraulic chamber 5A. The tilt piston 5B changes its capacity by pressure oil supplied and discharged into the hydraulic chamber 5A. The actuator 3 is driven in the direction of arrow A or B together with the tilt piston 3B of the actuator 3 to tilt the variable displacement section 2 of the hydraulic motor 1 between the maximum tilt side and the minimum tilt side.

The capacity switching valve 4 has a pressure oil supply / discharge port 41A1 connected to the hydraulic chamber 3A of the variable capacity actuator 3,
The pressure oil supply / discharge port 41A2 connected to the hydraulic chamber 5A of the variable capacity actuator 3, the shuttle valve 13, and the control line 14
High pressure port 41B connected via
Has a tank port 41C connected to it.

43A is a first throttle passage communicating between the high pressure port 41B and the pressure oil supply / discharge port 41A1, 43B is a fourth throttle passage communicating between the pressure oil supply / discharge port 41A2 and the tank port 41C, and 44A is a pressure oil supply. A second throttle passage that communicates between the discharge port 41A1 and the tank port 41C, and a third throttle passage 44B that communicates between the high-pressure port 41B and the pressure oil supply / discharge port 41A2.

Next, the details of the capacity switching valve 4 will be described with reference to FIGS.
Explanation will be made using 0.

FIG. 7 is a sectional view of the capacity switching valve 4 when the pressure oil supply / discharge port 41A1 is connected to the tank port 41C and the pressure oil supply / discharge port 41A2 is connected to the high pressure port 41B. Supply / discharge port 41A1 is high pressure port 41
B, and a cross-sectional view of the capacity switching valve 4 when the pressure oil supply / discharge port 41A2 is connected to the tank port 41C, FIG.
FIG. 10 is a sectional view of the capacity switching valve 4 as viewed from the line A in FIG.
FIG. 9 is a sectional view of the capacity switching valve 4 as viewed from the roll of FIG.

In these figures, the switching valve 4 comprises a valve casing 45, a spool 47 and the like. The switching valve 4 is spaced apart in the axial direction of the spool sliding hole 46, and is provided with a tank port 41C, pressure oil supply / discharge ports 41A1, 41A2, a high pressure A port 41B and a pilot port 41D are formed.

Inside the spool 47, a small-diameter first throttle passage 43A, a second throttle passage 44A, a third throttle passage 44B,
A high-pressure port 41B and a first throttle passage 4 are provided on the outer peripheral side of the spool 47.
A first notch 52A communicating with the 3A or the third throttle passage 44B, the pressure oil supply / discharge port 41A1, and the first throttle passage 43
A second notch 53A for communicating or blocking A, a fifth notch 53B for communicating or blocking the pressure oil supply / discharge port 41A2 and the third throttle passage 44B, a tank port 41C or a pressure oil supply / discharge port 41A2. A third notch 51B communicating with or blocking the fourth throttle passage 43B;
A fourth notch 51C that communicates or blocks 1C and the fourth throttle passage 43B or an annular groove 51A as a communication path that connects or blocks the pressure oil supply / discharge port 41A1 to or from the tank port 41C is formed. The annular groove 51A is configured to always communicate with the tank port 41C via the second throttle passage 44A.

First throttle passage 43A, third throttle passage 44
B, the fourth throttle passage 43B is a small-diameter throttle passage provided inside the spool 47 in a radial direction substantially perpendicular to the axial direction.

The first notch 52A and the second notch 53A
The high pressure port 41B and the pressure oil supply / discharge port 41A1
And the second notch 52A and the fifth notch 53.
B, the high pressure port 41B and the pressure oil supply / discharge port 41A
And the third notch 51B and the fourth notch 5 are connected to each other through a third throttle passage 44B.
By 1C, the pressure oil supply / discharge port 41A2 and the tank port 41C are configured to be communicated or cut off via the fourth throttle passage 43B.

The first throttle passage 43A and the third throttle passage 44B
Are pressure oil supply / discharge ports 41A1 and 41A from high pressure port 41B.
When the pressure oil flows toward A2, the flow rate of the pressure oil is controlled (restricted) by giving a throttling action to the pressure oil.

As shown in FIGS. 9 and 10, the notches 51B, 51C, 52A, 53A, 53B are provided on the outer peripheral side of the spool 46, and the second, fifth and third notches 53A are provided. , 53B, 51B and the first and fourth notches 52A, 51C are formed by grooves extending in the axial direction at positions 180 degrees apart from each other in the circumferential direction.

When the displacement switching valve 4 switches from the first switching position to the second switching position, the first notch 52A communicates with the high-pressure port 41B and the first throttle passage 43A, and the second notch 52A. The notch 53A is provided so as to communicate with the pressure oil supply / discharge port 41A1 and the first throttle passage 43A, and the third cutout 51B is formed with the pressure oil supply / discharge port 41A2 and the fourth throttle passage 43A.
B, and the fourth notch 51C is connected to the tank port 41C.
And the fourth throttle passage 43B.

The second throttle passage 44A and the fourth throttle passage 43B
When the pressure oil flows from the pressure oil supply / discharge ports 41A1 and 41A2 to the tank port 41C, the flow rate of the pressure oil is controlled (restricted) by giving a throttling action to the pressure oil.
doing.

The capacity switching valve 4 supplies the hydraulic oil from the shuttle valve 13 to the hydraulic chamber 3A of the variable capacity actuator 3 by connecting the high pressure port 41B to the pressure oil supply / discharge port 41A1 at the second switching position. The tilting piston 3B of the variable displacement actuator 3 is driven in the B direction, and the pressure oil supply / discharge port 41A2 is connected to the tank port 41C, thereby allowing the pressure oil from the hydraulic chamber 5A of the variable displacement actuator 5 to be supplied and discharged. It is discharged to the tank port 41C side via the port 41A1, and the tilt piston 5B of the variable capacity actuator 5 is driven in the B direction.

When the capacity switching valve 4 is switched to the first switching position by the spring 42, the pressure oil supply / discharge port 41
A1 is communicated with the tank port 41C to discharge the pressure oil from the hydraulic chamber 3A of the variable capacity actuator 3 to the tank port 41C via the pressure oil supply / discharge port 41A1, and the tilt piston 3B of the variable capacity actuator 3
Is driven in the direction A, and the high pressure port 41B communicates with the pressure oil supply / discharge port 41A2, so that the pressure oil from the shuttle valve 13 can be supplied to the hydraulic chamber 5 of the variable capacity actuator 5.
A, and drives the tilting piston 5B of the variable capacity actuator 5 in the A direction.

Next, the operation of the displacement control device for a hydraulic rotary machine according to this embodiment will be described.

First, referring to FIG. 6, when the capacity selection valve 16 is switched to the large capacity position (c), the pilot line 17 is connected to the tank 7 and the tank pressure is attained. As shown in FIG. 7, the capacity switching valve 4 connects the pressure oil supply / discharge port 41A1 to the tank port 41C, and the displacement switch valve 4 is switched from the hydraulic chamber 3A of the variable capacity actuator 3 to the pressure oil supply / discharge port. 41
A, by discharging the pressure oil to the tank port 41C side through the A, the tilting piston 3 of the variable capacity actuator 3
B in the direction of arrow A, and pressurized oil supply / discharge port 41
A2 communicates with the high-pressure port 41B, and by supplying hydraulic oil from the shuttle valve 13 to the hydraulic chamber 5A of the variable capacity actuator 5 via the hydraulic oil supply / discharge port 41A2, the tilting piston 5B of the variable capacity actuator 5 is turned to the arrow. The motor is driven in the direction A to set the motor capacity of the hydraulic motor 1 to a large capacity state.

In this state, the control valve 9 is switched from the neutral position (A) to the switching position (B) or (C), and the hydraulic motor 1
When the hydraulic oil is supplied from the hydraulic pump 6, the hydraulic motor 1 is driven to rotate at a high torque by the hydraulic pressure at this time, and the hydraulic shovel can be driven at a low speed. In this case, the motor capacity is large and the load pressure of the hydraulic motor 1 can be prevented from greatly increasing, so that the discharge pressure of the hydraulic pump 6 and the like can be prevented from becoming excessively high, and the overload of the prime mover can be prevented. And smooth running up a hill or the like can be performed.

Next, in FIG. 6, when the capacity selection valve 16 is switched to the small capacity position (d), the pilot pressure of the pressure Pa set by the pressure reducing valve 18 is applied via the pilot pipe 17 to the capacity switching valve 4. Is switched from the switching position (a) to the switching position (b) against the spring 42. As a result, as shown in FIGS. 8 to 10, in the capacity switching valve 4, the high pressure port 41 </ b> B communicates with the pressure oil supply / discharge port 41 </ b> A <b> 1, and the pressure oil from the shuttle valve 13 flows through the control line 17 to the variable capacity actuator. 3, the tilting piston 3B moves in the direction of arrow B, and the hydraulic oil supply / discharge port 41
A2 communicates with the tank port 41C, the hydraulic oil in the hydraulic chamber 5A of the variable displacement actuator 5 is discharged, and the tilt piston 5B moves in the direction of arrow B to set the motor capacity of the hydraulic motor 1 to the small capacity state. .

Here, the high pressure port 41B communicates with the pressure oil supply / discharge port 41A1 via the first notch 52A, the first throttle passage 43A, and the second notch 53A. Of the first throttle passage 4
While the flow rate is controlled (restricted) by 3A, it is supplied to the pressure oil supply / discharge port 41A1 to prevent the pressure oil from the shuttle valve 13 from being rapidly supplied to the hydraulic chamber 3A of the variable capacity actuator 3. Further, since the pressure oil supply / discharge port 41A2 communicates through the fourth notch 51B, the fourth throttle passage 43B, and the fifth notch 51C,
Sudden discharge of pressure oil from the hydraulic chamber 5A of the variable displacement actuator 5 is suppressed. As a result, the displacement variable section 2 of the hydraulic motor 1 can be smoothly and stably tilted from the large tilt side, and the traveling speed of the vehicle is not suddenly changed, so that vibration or impact is given to the driver. Can be prevented.

In FIG. 6, when the capacity selection valve 16 is switched from the small capacity position (d) to the large capacity position (c), as shown in FIG. 7, the pressure oil supply / discharge port 41A1 is connected to the second throttle. The pressure oil from the pressure oil supply / discharge port 41A1 communicates with the tank port 41C via the passage 44, and is discharged to the tank port 41C while its flow rate is controlled (restricted) by the second throttle passage 44A. The pressure oil from the shuttle valve 13 is supplied to the variable displacement actuator 5 through the third throttle passage 44B, and the flow rate of the pressure oil from the shuttle valve 13 is restricted (suppressed) by the third throttle passage 44B. Abrupt changes in the tilt angle of the variable displacement section 2 can be prevented, and the variable displacement section 2 of the hydraulic motor 1 can be tilted and driven smoothly and stably from the small tilt side, so that the traveling speed of the vehicle changes suddenly. This Vibration and impact to the driver by can be prevented.

As described above, also in this embodiment, it is possible to smoothly and stably switch the capacity of the hydraulic motor from a small capacity to a large capacity and from a large capacity to a small capacity. A rapid change in the flow rate can be effectively prevented. Therefore, for example, the traveling speed of the excavator can be changed smoothly, and the ride comfort and maneuverability of the driver can be improved.

The throttle passages 43A, 43B, 44A,
Since the switches 44B are provided separately, the switching speed can be arbitrarily changed depending on the capacitance switching direction by changing the opening area of each of the throttle passages.

The throttle passages 43A, 43B, 44
Since A and 44B are provided collectively in the capacity switching valve 4, the apparatus can be configured compact without complicating the apparatus, which contributes to downsizing of the apparatus.

The throttle passages 43A, 43B, 44
Since A and 44B are small-diameter throttles, the moving speed of the tilting pistons 3B and 5B of the variable capacity actuators 3 and 5 can be reduced with a machine difference due to a processing error or the like.

The throttle passages 43A, 43B, 44
Since the A and 44B are provided so as to penetrate in a direction substantially perpendicular to the sliding displacement direction, there is no need to provide a switching function in the throttle passage, so that the switching function and the throttle function can be made independent, and the capacity switching valve is provided. Is easy to process.

[0073]

As described above in detail, according to the first aspect of the present invention, when the pressure oil supply / discharge port of the capacity switching valve is communicated with the high pressure port to change the capacity of the hydraulic rotating machine, By controlling (restricting) the flow rate of the pressure oil supplied to the pressure oil supply / discharge port by a small-diameter throttle passage provided on the spool, it is possible to prevent the sudden supply of the pressure oil to the variable capacity actuator. it can.

According to the second aspect of the present invention, the throttle passage is provided so as to communicate in a direction substantially perpendicular to the sliding displacement direction of the spool. Because it was provided in the middle of the port,
The throttle passage may be machined so that the spool communicates with the shortest distance. The spool can be shortened in the axial direction, the entire apparatus can be made compact, and machining of the throttle passage can be easily performed.

Further, according to the third aspect of the present invention, when the pressure oil supply / discharge port of the capacity switching valve is connected to the tank port in order to change the capacity of the hydraulic rotary machine, the pressure oil supply / discharge port is connected to the tank port. By controlling (restricting) the flow rate of pressure oil discharged to the spool by a small-diameter throttle passage provided in the spool, it is possible to prevent the pressure oil of the variable displacement actuator from being rapidly discharged to the tank port.

Further, according to the present invention, when one pressure oil supply / discharge port of the capacity switching valve is communicated with the high pressure port in order to change the capacity of the hydraulic rotary machine, the high pressure port is connected to the one high pressure port. The flow rate of the pressure oil supplied to the pressure oil supply / discharge port is controlled (restricted) by one small-diameter throttle passage provided on the spool, and the other pressure oil supply / discharge port of the capacity switching valve is connected to the tank port. By controlling (restricting) the flow rate of the pressure oil supplied from the pressure oil supply / discharge port to the tank port by the other small-diameter throttle passage provided on the spool, the pressure oil is rapidly supplied to the variable capacity actuator. Can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit of a displacement control device for a hydraulic rotary machine according to a first embodiment of the present invention.

FIG. 2 shows a pressure oil supply / discharge port 41A according to the first embodiment.
Switching valve 4 when is connected to tank port 41C
FIG.

FIG. 3 is a pressure oil supply / discharge port 41A according to the first embodiment.
FIG. 5 is a cross-sectional view of the capacity switching valve 4 when is connected to the high-pressure port 41B.

FIG. 4 is a cross-sectional view of the capacity switching valve 4 as viewed from the line II in FIG. 3;

FIG. 5 is a sectional view of the capacity switching valve 4 as viewed from the roller in FIG. 3;

FIG. 6 is a hydraulic circuit of a displacement control device for a hydraulic rotary machine according to a second embodiment of the present invention.

FIG. 7 shows a pressure oil supply / discharge port 41A according to a second embodiment.
1 is a sectional view of the capacity switching valve 4 when the tank 1 is connected to the tank port 41C and the pressure oil supply / discharge port 41A2 is connected to the high pressure port 41B.

FIG. 8 shows a pressure oil supply / discharge port 41A according to a second embodiment.
1 is a sectional view of the capacity switching valve 4 when the pressure switching valve 4 is connected to the high pressure port 41B and the pressure oil supply / discharge port 41A2 is connected to the tank port 41C.

FIG. 9 is a cross-sectional view of the capacity switching valve 4 as viewed from a line A in FIG.

FIG. 10 is a sectional view of the capacity switching valve 4 as viewed from the roller in FIG. 8;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hydraulic motor 2 Variable capacity part 3,5 Variable capacity actuator 4 Capacity switching valve 6 Hydraulic pump 7 Tank 9 Control valve 13 Shuttle valve 14 Control line 15 Pilot pump 16 Capacity selection valve 17 Pilot line 41A, 41A1,41A2 Pressure oil Supply / discharge port 41B High pressure port 41C Tank port 42 Spring 43, 43A First throttle passage 44, 44A Second throttle passage 44B Third throttle passage 43B Fourth throttle passage 45 Valve casing 51B Fourth notch 51C Fifth notch 52, 52A First notch 53, 53A Second notch 53B Third notch

Claims (4)

[Claims] A variable-capacity hydraulic rotating machine having a variable-capacity section; and driving the variable-capacity section by supplying and discharging pressure oil to reduce the capacity of the hydraulic rotating machine to a small capacity or a large capacity. A variable displacement actuator to be switched; a first switching position for connecting a pressure oil supply / discharge port connected to the variable capacity actuator to a tank port; and a second switching position for communicating the pressure oil supply / discharge port to a high pressure port. And a capacity switching valve for selectively supplying and discharging the pressure oil of the variable displacement actuator.A capacity control device for a hydraulic rotating machine comprising: a capacity switching valve, the pressure oil supply / discharge port; A high pressure port, a valve casing in which the tank port and the pilot port are formed, and a high pressure port or a tank port in which the pressure oil supply / discharge port is slidably fitted in the valve casing. A spool for selectively communicating or blocking, a spring chamber formed between one end of the spool and the valve casing and always communicating with the tank port; and a spool disposed in the spring chamber and always attached to the spool in the axial direction. A hydraulic pressure pilot which is formed in the valve casing at the other end of the spool and is supplied with pilot pressure from the pilot port to slide and displace the spool against the spring. A small-diameter throttle passage formed inside the spool and provided so as to radially penetrate the spool; a high-pressure port and the throttle provided at an outer periphery of the spool at the second switching position A first notch communicating one end of a passage; and a pressure oil supply / discharge port and the throttle provided at an outer periphery of the spool when the second switching position is provided. Capacity control apparatus for hydraulic rotary machine, characterized in that it comprises a second notch which communicates the other end of the road, the. 2. The pressure oil supply / discharge port according to claim 1, wherein the throttle passage is provided so as to penetrate in a direction substantially perpendicular to a sliding displacement direction of the spool, and the pressure oil supply / discharge port is in the second switching position. A capacity control device for a hydraulic rotating machine, wherein the capacity control device is provided at a position intermediate between the hydraulic pressure machine and the high pressure port. 3. The method according to claim 1, wherein
In one claim, the spool has a communication passage for communicating or blocking the pressure oil supply / discharge port with a tank port, and the small-diameter throttle passage is provided so as to communicate the communication passage with the spring chamber. A capacity control device for a hydraulic rotating machine, characterized in that the capacity is controlled. 4. A variable displacement type hydraulic rotary machine having a variable capacity section, wherein said variable capacity section is driven by supplying and discharging pressure oil to reduce the capacity of said hydraulic rotary machine to a small capacity or a large capacity. A plurality of variable capacity actuators to be switched, and a pressure oil supply / discharge port connected to one of the variable capacity actuators is communicated with a tank port, and a pressure oil supply / discharge port connected to the other variable capacity actuator is connected to a high pressure port. A first switching position to be communicated, and a pressure oil supply / discharge port connected to the one variable capacity actuator are connected to a high pressure port, and a pressure oil supply / discharge port connected to the other variable capacity actuator is connected to a tank port. And a capacity switching valve for selectively switching between a second switching position that communicates with the valve and supplying and discharging the pressure oil of each of the variable capacity actuators. In the displacement control device for a turning machine, the displacement switching valve includes: a valve casing in which the pressure oil supply / discharge port, the high pressure port, the tank port, and the pilot port are formed; and a slidable fit in the valve casing. A spool inserted and selectively communicating or blocking each of the pressure oil supply / discharge ports with a high pressure port or a tank port; and a spring chamber formed between one end of the spool and a valve casing and constantly communicating with the tank port. A spring disposed in the spring chamber and constantly biasing the spool in the axial direction; and a pilot pressure supplied from the pilot port formed in the valve casing at the other end of the spool. A hydraulic pilot portion for slidingly displacing the spool against the spring; and a radially penetrating through the spool formed inside the spool. A plurality of small-diameter throttle passages provided so as to be provided; a first notch provided on the outer periphery of the spool and communicating with the high-pressure port and one end of one of the throttle passages at the second switching position; A second cutout provided on the outer periphery of the spool and connected to the one of the variable displacement actuators and connected to the other end of the one of the throttle passages at the time of the second switching position; A third notch provided on the outer periphery of the spool and connected to the pressure oil supply / discharge port connected to the other variable capacity actuator at the second switching position and one end of the other throttle passage; A fourth cutout provided on the outer periphery of the spool and communicating the tank port and the other end of the other throttle passage at the time of the second switching position. The amount control device.