JPH0771415A - Control circuit for hydraulic motor - Google Patents

Abstract

PURPOSE:To ensure proper holding state on a slope while improving the operability of the turning device of a construction machine or the like, and realizing shock reduction or the like at the time of a gear change. CONSTITUTION:The serial hydraulic circuit of a communication valve 29 and a variable throttle valve 30 is laid between the ports 21a and 21b of a hydraulic motor 21. The communication valve 29 keeps the port 21a communicated with the port 21b when a rotation direction selector valve 24 is operating according to a turning signal generated from an operation valve 28, and also over a certain time from the interruption of the turning signal to the occurrence of the steady state of hydraulic fluid in a cylinder 36 via the serial circuit of a throttle 44 and a flow control valve 45. In this case, when the hydraulic motor 21 stops rotating, no hydraulic pressure is introduced from the ports 21a and 21b and, therefore, the first selector valve 41 becomes inoperative. Thus, hydraulic fluid in the cylinder 36 is immediately discharged to a tank 46 via a passage 37, and a brake 35 holds a rotational shaft in braked state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic motor control circuit for driving a turning device such as a construction machine.

[0002]

2. Description of the Related Art A typical conventional prior art hydraulic motor control circuit is shown in FIG. The hydraulic motor 1 has ports 1a and 1b that are a pair of pressure liquid supply ports. The rotation direction of the rotary shaft 2 is switched depending on which of the ports 1a and 1b is supplied with the pressurized liquid. An inertial body 3 such as a turning device of a construction machine is connected to the rotary shaft 2. The rotation direction of the hydraulic motor 1 is switched by the rotation direction switching valve 4. The hydraulic fluid from the tank 6 is pressurized by the hydraulic pump 5 to the rotation direction switching valve 4, and the pressurized liquid is supplied. Switching of the rotation direction switching valve 4 is performed by the pilot pressure from the operation valve 8. When the operation valve 8 is in the neutral position, the pressure oil from the hydraulic pump 5 is not supplied to the hydraulic motor 1.

A communication valve 9 is connected between the ports 1a and 1b. When the communication valve 9 operates according to a command from the command device 10, the communication valve 9 connects the ports 1a and 1b. Relief valves 11 and 12 and check valves 13 and 14 are also connected to the ports 1a and 1b, respectively.

By connecting the ports 1a and 1b with the communication valve 9, it is possible to improve the operability of the turning operation of the inertial body 3 by the hydraulic motor 1 and reduce the shock when the hydraulic motor 1 is accelerated or decelerated. it can. However, port 1
If the a and the 1b are always communicated with each other, there arises a problem in holding the construction machine when it is used on a slope such as a slope. That is, if the ports 1a and 1b are in communication with each other, the hydraulic motor 1 may undesirably rotate due to an external force such as gravity applied to the inertial body 3. Therefore, the command device 10 switches the communication valve 9 so that the ports 1a and 1b are shut off from each other. In this way, port 1a,
The prior art for selectively connecting 1b to each other as necessary is as follows.
For example, Japanese Utility Model Publication No. 2-84001 and Japanese Utility Model Publication No. 2-84.
No. 002, etc.

[0005]

In the conventional hydraulic motor control circuit, the switching of the communication valve 9 connected between the ports 1a and 1b of the hydraulic motor 1 does not detect the actual rotation state of the hydraulic motor. Have been to. Therefore, due to malfunction of the communication valve or forgetting to operate it, the hydraulic circuit becomes unintentional, resulting in poor operability, large shock during acceleration / deceleration, or danger of being unable to maintain slopes. May occur. Further, an external command device is required to switch the communication valve, which complicates the structure of the hydraulic circuit.

An object of the present invention is to provide a control circuit for a hydraulic motor which can surely operate the communication valve when the hydraulic motor rotates and can shut off the ports reliably when the hydraulic motor is stopped.

[0007]

SUMMARY OF THE INVENTION The present invention responds to a brake for braking a rotary shaft of a hydraulic motor, a rotation command pressure to the hydraulic motor, and a port pressure of the hydraulic motor.
A switching valve that releases the brake when the rotation command pressure or the port pressure is generated, and a hydraulic output that operates the brake when neither the rotation command pressure nor the port pressure is generated, and the port of the hydraulic motor. And a communication valve that connects the ports of the hydraulic motor to each other only when the hydraulic pressure for releasing the brake is generated in response to the hydraulic pressure output from the switching valve. It is a control circuit.

Further, the present invention is connected between a rotation detector for detecting the rotation of the rotary shaft of the hydraulic motor and the port of the hydraulic motor, and the hydraulic pressure is detected only when the rotation is not detected in response to the output from the rotation detector. A control circuit for a hydraulic motor, comprising: a communication valve for communicating between ports of the motor.

Further, the present invention is characterized in that a serial hydraulic circuit of the communication valve and the throttle valve is connected between the ports of the hydraulic motor.

[0010]

According to the present invention, the brake for braking the rotary shaft of the hydraulic motor is controlled by the hydraulic pressure output from the switching valve. The switching valve releases the brake when the rotation command pressure to the hydraulic motor or the port pressure of the hydraulic motor is generated, and does not brake the rotary shaft of the hydraulic motor. Since the rotary shaft of the hydraulic motor has inertia, it does not stop immediately even if the rotation command pressure stops. The switching valve generates a hydraulic pressure output for releasing the brake when the hydraulic motor continues to rotate. This hydraulic output connects the communication valve between the ports of the hydraulic motor, improving operability,
It is possible to reduce shock during acceleration / deceleration. Since the communication valve is not connected between the ports when the rotary shaft is stopped, it is possible to prevent the hydraulic motor from undesirably rotating due to an external force or the like.

According to the invention, the rotation of the rotary shaft of the hydraulic motor is detected by the rotation detector. The communication valve connected between the ports of the hydraulic motor allows the ports to communicate with each other only when rotation is detected by the rotation detector to improve operability and reduce shocks during acceleration / deceleration. Since the ports are not communicated with each other when the rotary shaft of the hydraulic motor is stopped, it is possible to prevent undesired rotation of the hydraulic motor.

Further, according to the invention, a serial hydraulic circuit including a communication valve and a throttle valve is connected between the ports of the hydraulic motor.
Since it becomes easy to adjust the throttle amount of the throttle valve, it becomes easy to set an appropriate operating state according to the application.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of an embodiment of the present invention. The hydraulic motor 21 that can rotate in two directions has a pair of ports 2
1a and 21b are provided. When one of the ports 21a and 21b serves as a pressure liquid supply port, the other serves as a pressure liquid discharge port.
The rotary shaft 22 of the hydraulic motor 21 is connected to a working device such as a turning device of a construction machine. An inertial moment of the turning device is represented as an inertial body 23. The rotation direction switching valve 24 switches the rotation direction of the hydraulic motor 21. The rotation direction switching valve 24 is a three-position switching valve,
At the neutral position, the pressure liquid is not supplied to the ports 21a and 21b. The hydraulic oil in the tank 26 is pressurized and supplied to the rotation direction switching valve 24 by the hydraulic pump 25. The switching of the rotation direction switching valve 24 is performed by the pilot pressure of the operation valve 28.

A serial hydraulic circuit of a communication valve 29 and a variable throttle valve 30 is connected between the ports 21a and 21b of the hydraulic motor 21. Further, relief valves 31, 32 and check valves 33, 34 are connected to the ports 21a, 21b, respectively.

In order to brake the rotary shaft 22, the brake 3
5 are provided. The brake 35 is driven by the cylinder 36. A spring is provided in the cylinder 36, and when the pressurized liquid is not supplied through the passage 37, the rotary shaft 2
2 will be braked.

Both ports 21a, 21b of the hydraulic motor 21
A shuttle valve 38 is also connected in between. A shuttle valve 39 is connected between the pilot circuits of the rotation direction switching valve 24. The pressure liquid from the pilot pressure source 40 flows into the passage 37 for releasing the brake 35, and the first switching valve 4
It is supplied via the first and second switching valves 42. The first switching valve 41 is a two-position three-port valve, and when the pilot pressure is not applied, the passage 37 is in communication with the tank 43. The first switching valve 41 is switched by the pilot pressure of two systems. One is the pilot pressure from the shuttle valve 38, and the other is the pilot pressure from the shuttle valve 39. The second switching valve 42 is controlled by the pilot pressure from the shuttle valve 39. When the pilot pressure is not applied, the output port is connected to the tank 46 via the throttle 44 and the flow control valve 45. The tanks 43 and 46 are the same tanks as the tank 26.

When the operation valve 28 is operated to generate a turning command, the rotation direction switching valve 24 is switched from the neutral position to either direction, and the pressure liquid from the hydraulic pump 25 is transferred to any port of the hydraulic motor 21. 21a, 21b. At this time, the first and second via the shuttle valve 39
The switching valves 41 and 42 are also activated, the pilot pressure source 40 and the passage 37 communicate with each other, and the brake 35 is released against the spring in the cylinder 36. When the operation valve 28 is operated to stop the turning command, the rotation direction switching valve 24 returns to the neutral position. Further, since the pilot pressure is not derived from the shuttle valve 39, the second switching valve 42 returns to the state shown in FIG. However, due to the inertial body 23, the hydraulic motor 2
1 cannot be stopped immediately, and the pressure of either of the ports 21a and 21b is maintained at a high pressure before the stop. Therefore, pilot pressure is applied to the first switching valve 41 via the shuttle valve 38, and the passage 37 is connected to the throttle 44 and the flow rate control valve 45 via the second switching valve 42. The flow control valve 45 controls the amount of hydraulic oil flowing through the throttle 44 to a small value. Therefore, it takes a certain period of time to discharge the hydraulic oil from the cylinder 36, the hydraulic pressure in the passage 37 is kept constant during that time, and the brake 35 is kept in the released state. It becomes conductive.

FIG. 2 shows the relationship between the rotation speed of the hydraulic motor 21 and the pilot pressure. That is, FIG. 2A shows an example of changes in the rotation speed of the hydraulic motor 21.
(2) shows the change in the hydraulic pressure of the passage 37 at that time, and FIG. 2 (3) shows the turning command at that time. When the turning command Pi is given from time t1 to t2, the rotation speed of the hydraulic motor 21 increases from time t1 to t2. Time t2
When the turning command Pi is stopped at, the rotation of the hydraulic motor 21 does not stop immediately, but decreases after time t3 and then stops. During this time period from t1 to t3, the pressure P is applied to the passage 37.
Occurs. When the time from time t1 to t2 is sufficiently long, the rotation speed of the motor 21 reaches the maximum value, and then keeps the maximum value.

If the pressure P in the passage 37 is above a certain value,
A communication valve 2 is provided between the ports 21a and 21b of the hydraulic motor 21.
9 is connected to a series hydraulic circuit of the conduction side of 9 and the variable throttle valve 30 to establish a communication state. It should be noted that, unlike the prior art shown in FIG. 4, the throttle valve 30 is not provided inside the communication valve 9, but the variable throttle valve 30 is independently provided outside the communication valve 29. is there. When the variable throttle valve 30 is independently provided outside as described above, the throttle amount can be adjusted according to the nature of the work, and the operability can be further improved. For example, even in a hydraulic excavator or the like, the necessity of micro-operation is different between a normal excavation work and a work as a substitute for a crane. If the variable throttle valve 30 is independently provided outside, adjustment can be easily performed according to necessary operability. Needless to say, a throttle may be built in the communication valve 29 as in the prior art.

When the hydraulic motor 21 is rotating,
Hydraulic pressure is derived from at least one of the ports 21a and 21b. This hydraulic pressure operates the first switching valve 41 via the shuttle valve 38. When the rotation of the hydraulic motor 21 is stopped and the first switching valve 41 becomes inoperative,
The passage 37 is in communication with the tank 43, the hydraulic oil in the cylinder 36 is immediately discharged, and the rotating shaft 22 is reliably braked by the brake 35. The pressure in the passage 37 is
The brake 35 slips due to external load, and the port 21
Even if the pressure is generated from a and 21b and the first switching valve 41 operates, the second switching valve 42 does not operate and therefore does not rise.
Therefore, the holding capacity for an external load does not change on the way.

The relief valves 31 and 32 are used for the hydraulic motor 21.
Prevents the oil pressure from rising above a certain value when the rotation of is stopped forcibly. The shuttle valves 33 and 34 are connected to the negative pressure side ports 21a and 2 during the times t2 to t3 shown in FIG.
It is provided to supply hydraulic oil from the tank 26 to 1b.

FIG. 3 shows the configuration of another embodiment of the present invention. The present embodiment is similar to the embodiment shown in FIG. 1, and the corresponding portions bear the same reference numerals. Notable is the rotating shaft 2
The rotation state of No. 2 is detected by the rotation sensor 50, and the communication valve 29 is driven by its output. That is, as long as the rotary shaft 22 is rotating, the communication valve 29 is in the operating state, and the ports 21a and 21b of the hydraulic motor 21 are communicated with each other to improve the operability.

The rotation sensor 50 magnetically or optically detects the rotation state of the rotation shaft 22. Since this embodiment is a hydraulic device, a magnetic device is preferably used rather than an optical device. For example, a gear is attached to the rotary shaft 22, a change in magnetic resistance between the rotary sensor 50 and the tip of the rotary sensor 50 is converted into an electric pulse signal, and the repetition period thereof is converted into a voltage. , Communication valve 29
To activate the communication.

[0024]

As described above, according to the present invention, the brake can be reliably released and the ports of the hydraulic motor can be communicated with each other while the rotary shaft of the hydraulic motor is rotating. As a result, the operability of the hydraulic motor is improved, and fine operation is facilitated. Also, shock during acceleration / deceleration is reduced. When the rotating shaft of the hydraulic motor is stopped, the brake operates and the ports of the hydraulic motor are not communicated, so that the hydraulic motor can be reliably held and undesired rotation can be prevented. Since such switching is performed automatically, there is no risk of erroneous external commands or forgetting each command. Also, an external command device is not required,
The structure of the hydraulic circuit becomes simple. Furthermore, since the ports communicate with each other, the drive torque just before the hydraulic motor stops is reduced,
The shock when the brakes are applied is reduced and the swing back due to the inertia of the rotating shaft is also reduced.

Further, according to the present invention, the ports of the hydraulic motor are communicated with each other only when the rotation of the rotary shaft of the hydraulic motor is detected. Therefore, the hydraulic motor undesirably rotates due to gravity when the rotary shaft is stopped. It can be surely prevented. When the hydraulic motor is rotating, the ports communicate with each other, so that the maneuverability is improved and the shock during acceleration / deceleration is reduced.

Further, according to the present invention, since the serial hydraulic circuit of the communication valve and the throttle valve is connected between the ports of the hydraulic motor, it becomes easy to adjust the throttle amount when communicating between the ports. . This makes it possible to adjust the aperture amount according to the application and further improve the maneuverability.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram of an embodiment of the present invention.

FIG. 2 is a graph showing an example of the operation of the embodiment shown in FIG.

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

FIG. 4 is a control circuit diagram of a conventional hydraulic motor.

[Explanation of symbols]

 21 hydraulic motor 21a, 21b port 22 rotary shaft 23 inertial body 24 rotational direction switching valve 25 hydraulic pump 26, 43, 46 tank 28 operating valve 29 communication valve 30 variable throttle valve 35 brake 36 cylinder 37 passage 38, 39 shuttle valve 40 pilot Pressure valve 41 First switching valve 42 Second switching valve 44 Throttle 45 Flow control valve 50 Rotation sensor

Claims (3)

[Claims] 1. A brake for braking a rotary shaft of a hydraulic motor, and a brake when the rotation command pressure or the port pressure is generated in response to a rotation command pressure to the hydraulic motor and a port pressure of the hydraulic motor. It is connected between the switching valve that generates a hydraulic output to activate the brake when neither the rotation command pressure nor the port pressure is released and the hydraulic motor port, and responds to the hydraulic output from the switching valve. And a communication valve for communicating between the ports of the hydraulic motor only when the hydraulic pressure for releasing the brake is generated. 2. A port of a hydraulic motor connected between a rotation detector for detecting rotation of a rotary shaft of the hydraulic motor and a port of the hydraulic motor, and only when rotation is not detected in response to an output from the rotation detector. A control circuit for a hydraulic motor, comprising: a communication valve for communicating the two. 3. The control circuit for the hydraulic motor according to claim 1, wherein a serial hydraulic circuit including the communication valve and the throttle valve is connected between the ports of the hydraulic motor.