JPS616404A - Braking device of hydraulic motor - Google Patents

Abstract

PURPOSE:To improve the safety by providing a brake circuit with a brake control valve adapted to operate on sensing pressure in a short circuit formed between a switch valve and a hydraulic motor. CONSTITUTION:A brake circuit between an operation valve 18 and a brake cylinder C is provided with brake control valve 32 adapted to operate on sensing pressure in a short circuit formed between a switch valve 15 and a hydraulic motor (m). In this arrangement, when the switch valve 15 is restored to its neutral position, a hydraulic brake is operated to stop the hydraulic motor (m). When pressure in main passages 19, 20 is decreased, the brake control valve 32 is switched to connect a pressure chamber 30 of the cylinder C to a tank, whereby a parking brake is forced to function. When a hydraulic brake gets out of order, as pressure is not generated in the main passages 19, 20, the parking brake is forced to function. Accordingly, the safely can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a braking system that includes a parking brake in addition to a hydraulic brake using a crossover type relief valve.

(Prior Art) FIG. 4 shows a conventional braking device, in which an operating valve l is provided between a pump p and a hydraulic motor m. When this switching valve 1 is in the application position shown, the tank passage 2
Pump p is connected to tank T via.

Furthermore, when this switching valve 1 is switched from the neutral position to either the left or right, one of the main passages 3.4 will communicate with the pump p, and the other will communicate with the tank T. Drive hydraulic motor m.

Since the main passage 3.4 is provided with a crossover type relief valve 5.6, the switching valve 1 is returned to the neutral position shown in the figure while the hydraulic motor m is being driven as described above. , a short circuit is formed on the downstream side of the switching valve 1, and one of the above crossover type relief valves functions to convert the inertial energy of the hydraulic motor into thermal energy, and provides play and key to the hydraulic motor m. multiply.

Further, a parking brake consisting of a disc 7 and a cylinder C acts on this hydraulic motor m.

In other words, a spring 10 is installed in the bottom side chamber 9 of this parking brake, and a pressure chamber 11 on the rod side
is connected to the solenoid valve 12. This solenoid valve 12 has a spring 13 when it is in its de-energized state.
The pressure chamber 11 is maintained at the normal position shown in the figure by the action of
Connect to tank T. And this solenoid valve 12
When the switching valve 1 is switched, it is switched to the right position as shown in the figure in conjunction with the switching, and the oil discharged from the auxiliary pump 14 is guided to the pressure chamber 11. If the oil discharged from the auxiliary pump 14 is supplied to the pressure chamber 11 in this way, the rod 8 will move toward the spring 10.
Move against the parking brake and release the parking brake. In other words, when driving the hydraulic motor, the parking brake is always in the released position.

When the switching valve 1 is returned to the neutral position shown in the figure from this brake-released state, a hydraulic brake whose main element is a crossover relief valve functions to apply a brake to the hydraulic motor. In other words, when this hydraulic brake starts to work,
When the switching valve l returns to the neutral position, a signal is sent to the solenoid valve 12, and the solenoid valve 12 returns to the normal position shown. However, after the switching valve 1 is returned to the neutral position, there is a slight delay in returning the solenoid valve 12 to the normal position.

Since the timing of the return of the solenoid valve 12 to the normal position is delayed in this way, the parking brake can be applied after the hydraulic motor m has stopped. Therefore, it is possible to prevent the parking brake from generating heat, and the hydraulic brake and parking brake function simultaneously.
It is possible to prevent abnormal force from acting on the strength member.

(Problems to be Solved by the Present Invention) 'In the conventional device as described above, in order to prevent heat generation, etc., the parking brake is applied only after the hydraulic motor has stopped. If the brakes fail, the brakes will not work at all until the parking brake is applied.
There was a problem that led to an extremely dangerous situation.

This invention is a brake control system that senses the pressure in a short circuit formed between an operating valve and a hydraulic motor, and connects the pressure chamber of the parking brake cylinder to the tank or cuts off the communication. It is an object of the present invention to provide a device that is provided with a valve and eliminates the above-mentioned conventional problems.

(Means for Solving the Problems) In order to solve the above problems, the present invention connects a switching valve between a pump and a hydraulic motor, and connects the switching valve and the hydraulic motor to a pair of Depending on the switching position of the switching valve, one of the main passages is connected to the pump and the other main passage is connected to the tank to drive the hydraulic motor. By returning the switching valve to the neutral position from the state in which the motor is being driven, a short circuit is formed between the two main passages 1, and a hydraulic brake is applied by the crossover type relief valve in the short circuit, and In a brake system for a hydraulic motor, the pressure chamber of the cylinder, which is the main element of the parking brake, is communicated with a tank to apply the parking brake after the hydraulic motor has stopped to a certain extent or completely. a hydraulic source that supplies pressure oil to the cylinder, an operating valve that is connected between the hydraulic source and the cylinder and that is switched in conjunction with the switching valve, and a pressure chamber between the operating valve and the cylinder. and a brake control valve connected to the control valve, and when the switching valve is in the neutral position, the operating valve connects a passage communicating with the brake control valve to the tank, and when the switching valve is switched to either the left or right side, the hydraulic pressure is controlled. a brake control valve that senses pressure in the main passage and maintains a position that communicates the pressure chamber of the cylinder with the tank when the pressure is lower than a set value; When the pressure in the main passage is higher than a set value, only oil is allowed to be supplied to the pressure chamber, and oil is prevented from returning from the pressure chamber.

(Operation of the present invention) Since the present invention is configured as described above, when the switching valve is returned to the neutral position after driving the hydraulic motor, the hydraulic brake is applied and the motor is stopped. When the hydraulic motor is stopped in this way, the pressure in the main passage becomes low, so the brake control valve is switched, and the pressure chamber of the parking brake cylinder is communicated with the tank, allowing the parking brake to function.

And when the hydraulic brake fails, no pressure is generated in the main passage, so the brake mentioned above.

The control valve switches to make the parking brake function.

(Embodiment of the present invention) The first embodiment shown in Fig. 1.2 has a pump p and a switching valve 1.
A branch passage 17 is connected to a pump passage 16 that connects the switching valve 15 to the switching valve 15.

The switching valve 15 and the hydraulic motor m are connected via a main passage 18.20, and a crossover relief valve 21.22, which is a main element of the hydraulic brake, is connected between these main passages 19.20. This is the same as the conventional method. Additionally, a pair of check valves 23.24 are provided between the main passages 18 and 20, and these check valves 23.24 are communicated with the tank T via a passage 25 to check the amount of leakage in the circuit. compensation and prevents cavitation from occurring.

The switching valve 15 connected to the hydraulic motor m in this way is
In the neutral position shown, both the pump passage 16 and the tank passage 26 are cut off from communication with the main passage 18,20.

Then, when the switching valve 15 is switched to the right side in the drawing,
A pump passage 16 connects to one main passage 19, and a tank passage 26 communicates with the other main passage 20. Also, if the switching valve 15 is switched to the left side in the drawing, one main passage 1
8 communicates with the tank passage 26, and the other main passage 20 communicates with the pump passage 18.

Therefore, if the switching valve 15 is switched to either the left or right side,
As the hydraulic motor m rotates, the switching valve 1 is opened in this state.
5 is returned to the neutral position, a short circuit is formed between the two main passages 18, 20, and the hydraulic brake is applied in the same manner as in the prior art.

In addition, a disk 27 provided in the cylinder C and the hydraulic motor m
A spring 28 is interposed in the bottom side chamber 28 of this cylinder C, and the pressure chamber 3o on the opposite side from the bottom side chamber 28 is connected to the connecting ball of the brake control valve 32 via the throttle 31. ) 32a.

The inflow boat 32b on the upstream side of this brake control valve 32 is connected to the operation valve 18, and the tank boat 32c is connected to the tank T.The specific configuration of this brake control valve 32 is as follows. As shown in Figure 2.

That is, the valve body of the brake control valve 32 is equipped with a spool 33, and a spring 34 is applied to one end of the spool 33 to normally maintain the normal position shown in the drawing. Further, a first and second annular groove 35.3B is formed around this spool 33, but when the spool 33 is in the normal position, the first annular groove 35 is formed in the first annular groove 35.3B formed on the side of the valve body. The second annular groove 36 corresponds to the first annular recess 37, and corresponds to both the second and third annular recesses 38.38, allowing these two annular recesses 38.38 to communicate. The second annular portion 38 communicates with the connection port 32a, and the third annular recess 38 communicates with the tank port 32c. In the above normal position, the pressure chamber 30 of the cylinder C is connected via the connection port 32a + second annular recess 38 → second annular groove 36 → third annular recess 39 → tank port 32c, Connects to tank T.

A check valve 40 is provided in the spool 33, and the check valve 40 is configured to only allow flow from the inflow boat 32b to the first annular groove 35.

Further, on the same axis as the spool 33, a small diameter portion 4 is provided.
1a and a large diameter portion 41b is slidably provided, and a first plunger 41 at the tip of the small diameter portion 41a is slidably provided.
The pressure receiving surface 41c is connected to one of the main passages 18.
It faces the pilot room 42.・Also, the small diameter portion 41
The second pressure-receiving surface 41d formed by using the step at the boundary between the large-diameter portion 41b and the large-diameter portion 41b is communicated with the other main passage 20.
It faces the second pilot room 43.

The brake control valve 32 normally maintains its normal position on the left side in FIG. The pressure oil flows into the inflow port 32b via the operating valve 18, and the pressure oil at this time acts on the end surface of the spool 33, so the spool 33 moves against the spring 34. do. When the spool 33 moves, the first annular groove 35 and the second annular recess 38
At the same time, the second annular groove 36 is removed from the second annular recess 38.

Therefore, the pressure oil that has flowed into the inflow port 32b flows into the pressure chamber 30 of the cylinder C via the check valve 40 → the first annular groove 35 → the second annular recess 38 → the connection port 32a. When the pressure oil flows into the pressure chamber 30 in this manner, the rod of the cylinder C moves against the spring 29, moves away from the disc 27, and releases the parking brake.

Furthermore, when the switching valve 15 is switched as described above, depending on the switching position, one of the main passages, for example, one main passage 18 communicates with the pump P, and the other main passage 20 communicates with the tank T. The pressure on the main passage 19 side at this time is transmitted to the first pilot chamber 42 and the auxiliary plunger 4
1 acts on the first pressure receiving surface 41c. On the other hand, when the main passage 2o side communicates with the pump p, the pressure of the main passage 2o is transmitted to the second pilot chamber 43 and acts on the second pressure receiving surface 41d of the auxiliary plunger 41.

Now, when the switching valve 15 is returned to the neutral position and the hydraulic brake is applied, the operating valve 18 will also return to the position shown in the figure, so the inflow port 32b will flow into the tank T via the operating valve 18. Communicate.

In this state, when pressure is maintained in either the main passage 18 or 2o, in other words, when the hydraulic motor m is not stopped, the pressure on the main passage side is maintained at the auxiliary plunger as described above. 41, the spool 33 remains in the right position in FIG. 1 due to the pressing force of the auxiliary plunger 41. That is, communication between the connection port 32a and the tank port 32c is cut off, and communication between the connection port 32a and the inflow boat 32b also remains cut off by the check valve 40. Therefore, the pressure within the pressure chamber 3o of the cylinder C remains maintained, and the parking brake remains released.

Then, when the hydraulic brake is applied and the hydraulic motor m is stopped to a certain extent, the pressure in the main passage decreases, and the pressing force of the auxiliary plunger 41 that was acting on that pressure is also released, and the spool 33 is released from the spring 34. This action returns the brake control valve 32 to its original position, and the brake control valve 32 returns to its normal position, which is the left position in FIG.

When the brake control valve 32 returns to the normal position in this way, the pressure chamber 3o of the cylinder C communicates with the tank T, so the rod tip comes into pressure contact with the disc 27 due to the action of the spring 29 on the bottom side chamber 2, and the cylinder C is parked. Brakes work.

Even if the switching valve 15 is returned to the neutral position while the hydraulic motor m is being driven as described above and the short circuit is formed between the main passages 18 and 20, if the hydraulic brake is malfunctioning, the hydraulic motor.

The oil discharged from m circulates through the short circuit with almost no resistance. Therefore, no pressure that would act on the auxiliary plunger 41 is generated in this main passage. Moreover, in this state, the inflow rate is 3
2b is also connected to the tank T, so the spool 33
No force acts on it to hold it in the right position in Figure 1.

Therefore, the spool 33 immediately returns to the normal position, so that the parking brake functions quickly.

With this device, even if the hydraulic brake fails as described above, the parking brake will function, so the danger that would occur if the hydraulic brake failed can be avoided. Furthermore, when the hydraulic brake is functioning normally, the parking brake will function after the hydraulic motor m has stopped for some time, so that no abnormal force will be applied to the strength member.

In the first embodiment, the oil discharged from the pump p is guided to the pressure chamber 30 of the cylinder C via the branch passage 17. Of course, pressure oil may also be introduced.

In the second embodiment shown in FIG. 3, an auxiliary pump 44 is provided outside the main pump p, and the oil discharged from the auxiliary pump 44 is
It is led to the cylinder C via the operation valve 18 and the brake control valve 32. In addition, this auxiliary pump 44 is connected to a pilot valve 45, and the pilot pressure output from this pilot pressure 45 is used to control the switching valve 15.
and the operating valve 18 can be switched simultaneously. The other configurations are the same as those of the first embodiment.

(Effects of the Invention) In this invention, since the parking brake functions after the hydraulic motor has stopped to a certain extent, there is no need to worry about the parking brake functioning while the hydraulic motor is driving and damaging the strength member. disappears.

Furthermore, when the hydraulic brake fails or does not function, the parking brake immediately functions, further improving safety.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of the first embodiment of the present invention, Figure 2 is a sectional view of the brake control valve, Figure 3 is a circuit diagram of the second embodiment, and Figure 4 is a conventional circuit diagram. . P...Pump, 15...Switching valve, 18...Operation valve, 18.20...Main passage, 21.22...Crossover type relief valve, C...Cylinder, 30...・
Pressure chamber, 32...brake control valve.

Claims (1)

[Claims] A switching valve is connected between the pump and the hydraulic motor, and the switching valve and the hydraulic motor are connected through a pair of main passages, and depending on the switching position of the switching valve, either one of the main passages is connected. is connected to the pump, and the other main passage is connected to the tank to drive the hydraulic motor, while returning the switching valve to the neutral position from the state in which the motor is being driven, thereby creating a connection between the two main passages. A short circuit is formed in the short circuit, and the hydraulic brake is applied by the crossover type relief valve in the short circuit, and after the hydraulic motor has stopped to a certain extent or completely, the pressure chamber of the cylinder, which is the main element of the parking brake, is closed to the tank. A hydraulic motor braking device configured to communicate with a hydraulic motor to apply a parking brake, the hydraulic motor supplying pressure oil to the pressure chamber of the cylinder, and the hydraulic motor connected between the hydraulic power source and the cylinder, and the switching An operating valve that switches in conjunction with the valve, and a brake control valve connected between the operating valve and the pressure chamber of the cylinder, the operating valve when the switching valve is in a neutral position,
A passage communicating with the brake control valve is connected to the tank, and when the switching valve is switched to either left or right, the hydraulic pressure source and the brake control valve are communicated, and the brake control valve senses the pressure in the main passage, When the pressure is lower than the set value, the pressure chamber of the cylinder is maintained in a position where it communicates with the tank, while when the pressure of the main passage is higher than the set value, only the oil is supplied to the pressure chamber. A hydraulic motor braking device configured to maintain a position that allows oil to return from the pressure chamber and prevents it from returning.