JPH0754643Y2 - Brake device for hydraulic motor - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a brake device for a hydraulic motor that drives a large inertial load, and more specifically, for a mechanical brake.
Regarding improvement of release operation.

[Prior Art] In order to stop a hydraulic motor that drives a large inertial load during rotation, normally, the pressure oil in the closed circuit of the hydraulic motor is kept at the set pressure of the brake valve and discharged to the tank to decelerate. -If the mechanical brake is used together with the mechanical brake to maintain the stopped state after stopping, it is economical because a mechanical brake with a small capacity can be selected. Furthermore, when a switching valve that supplies and shuts off pressure oil to the mechanical brake is connected to the main switching valve, braking is released and braking is automatically performed according to the operation of driving and stopping the hydraulic motor by the main switching valve. It eliminates the annoyance.

By the way, if the mechanical brake is activated before the hydraulic motor stops after the stop operation of the hydraulic motor by the main switching valve, heat is generated and the mechanical brake selected with a small capacity is worn very quickly. For this reason, the flow rate of the pressure oil discharged from the brake cylinder to the tank at the same time as the stop operation of the main switching valve is regulated by the throttle so that the brake operation timing coincides with the inertia body stop timing and more accurately. Attempts have been made to provide a pressure compensation mechanism in order to make the pressure difference before and after the restriction constant.

[Problems to be Solved by the Invention] However, if the viscosity of the pressure oil changes, the time required for a predetermined amount of pressure oil to pass through the throttle also changes, and the viscosity of the pressure oil increases as the oil temperature increases. The decrease shortens the delay time until the brake starts to operate, and the brake operates during the movement of the inertial body, resulting in wear of the brake member, while when the oil temperature becomes low, the delay time becomes significantly long and even after the load stops There was a problem that the mechanical brake did not operate for a time and the load moved from the position where it should be locked due to internal leakage of the hydraulic motor.

Therefore, the object of the present invention is to provide a brake device for a hydraulic motor, which can be reduced in size and weight while being free from consideration for wear of a mechanical brake, and which can prevent load runaway caused by delay in brake operation at low oil temperature. And

[Means for Solving the Problems] The present invention, which has been made for the purpose described above, has a brake (20) for braking and releasing an output shaft (21) of a hydraulic motor (1) and a built-in spring (22). Pilot pump (3) that brakes (20) and acts against the output of the spring (22)
A brake cylinder (4) for releasing the braking of the brake (20) by the pressure oil, a main switching valve (2) for switching the supply and discharge of the pressure oil that drives the hydraulic motor (1), and a tank from the brake cylinder (4). In a brake device for a hydraulic motor, which comprises a first throttle (11) for controlling a flow rate of pressure oil discharged to the first and a pressure compensation spool (9) for making a pressure difference before and after the first throttle (11) constant. A piston (7) provided coaxially with the pressure compensating spool (9) and having a pressure compensating spring (12) sandwiched between the piston (7) and a back chamber (8) of the piston (7). A second throttle (29) provided between the first throttle (11) and the downstream thereof and a spool connected to the spool of the main switching valve (2) are used for switching, and the main switching valve (2)
At the pressure oil supply / discharge position for driving the hydraulic motor (1), the oil passage communicating with the brake cylinder (4) and the pressure compensating spool (9) and the oil communicating with the back chamber (8) of the piston (7). The oil passage for supplying pressure oil from the pilot pump (3) is connected to the passage, and the downstream passage of the first throttle (11) and the tank are shut off, and the neutral valve of the main switching valve (2) is neutralized. In the position, the oil passage communicating with the brake cylinder (4) and the pressure compensation spool (9) and the oil passage communicating with the back chamber (8) of the piston (7) are connected from the pressure oil supply oil passage of the pilot pump (3). A brake device for a hydraulic motor provided with a switching valve (5) configured to shut off and connect a downstream passage of the first throttle (11) to a tank.

In this case, the main switching valve (2) is replaced with the pilot control valve (6).
By this, the pressure oil of the pilot pump (3) is connected to both pilot connection ports of the main switching valve (2) for control, or the first throttle (11) is connected to the pressure compensation spool (9). Incorporating the second throttle (29) in the piston (7), and further incorporating the first throttle, the second throttle, the pressure compensation spool and the piston in the case of the hydraulic motor, etc. Are more preferable.

[Operation] When the hydraulic motor (1) is driven, if the main switching valve (2) is operated to switch to either one, the discharge oil of the pump (23) passes through the main switching valve (2) and then the hydraulic motor (1). Is supplied to one side, discharged from the other side, returned to the tank through the main switching valve (2), and the hydraulic motor (1) is rotationally driven in one direction.
At the same time, the switching valve (5) connected to the main switching valve (2) is switched, and the pressure oil of the pilot pump (3) is supplied to the brake cylinder (4) through the switching valve (5) without delay and is built in. The braking of the brake (20) is released against the force of the spring (22). At this time, the brake cylinder (4)
Communication from the passage that joins the downstream of the first throttle (11) connected to the same circuit with the downstream of the second throttle (29) passing through the back chamber (8) of the piston (7) to the tank. Switching valve (5)
On the other hand, since the spring chamber (31) holding the pressure compensating spring (12) is always connected to the tank, pressure oil of the pilot pump (3) acts on the pressure compensating spool (9). The piston (7) also moves to the movable limit as the pressure oil of the pilot pump (3) acts on its back chamber (8) at the same time as it moves to a position where it counterbalances the elastic force of the pressure compensation spring (12). Therefore, the pressure compensating spring (12) held between the pressure compensating spool (9) and the piston (7) is balanced in a state of being maximally compressed.

When braking the drive of the hydraulic motor (1), when the main switching valve (2) is operated and returned to the neutral position together with the switching valve (5) that is connected, the main switching valve (2) is closed and the hydraulic motor (1) is closed.
Is controlled by the pressure oil discharged by continuously rotating under inertia load to start deceleration, while the switching valve (5) cuts off the pressure oil supply of the pilot pump (3), and The passage that joins the downstream of the throttle (11) and the downstream of the second throttle (29) is connected to the tank, and the confined pressure oil in the brake cylinder (4) passes through the first throttle (11). It is discharged at a flow rate according to the pressure difference before and after that. In the initial stage of discharge, the pressure difference before and after the first throttle (11) controlled by the pressure compensation spring (12) in the maximum compressed state is high and the discharge speed is fast, but the back chamber of the piston (7) is As the pressure oil of (8) is also cut off and gradually discharged through the second throttle (29), the piston (7) retracts and is placed between the pressure compensation spool (9) and the piston (7). The elastic pressure of the sandwiched pressure compensating spring (12) is reduced to reduce the pressure difference before and after the first throttle (11) and the discharge speed. In this way, the discharge speed of the pressure oil changes every moment during the discharge process, but the time from the start of discharge to the brake operation is constant unless the opening area of the first throttle (11) and the property of the pressure oil change. Become.

When the oil temperature decreases and the oil viscosity increases, it becomes difficult for the pressure oil discharged from the brake cylinder (4) to pass through the first throttle (11), which tends to delay the brake operation start timing. When the pressure oil in the back chamber (8) of (7) passes through the second throttle (29), the viscosity is increased, so that the discharge speed is reduced, and the elastic force of the pressure compensation spring (12) is reduced and the first This is offset by slowing down the pressure difference before and after the throttle (11), and the change in the discharge time, that is, the time until the brake is actuated is extremely small.

[Embodiment] A first embodiment of the present invention will be described below with reference to FIG. The output shaft 21 of the hydraulic motor 1 is braked / released by the brake 20. The brake cylinder (4) acts to brake the brake 20 by the output of the built-in spring 22, and releases the braking of the brake 20 by the pressure oil supplied from the pilot pump 3 against the output of the spring 22. Acts like. The main switching valve 2 is the hydraulic motor 1
The supply and discharge of the pressure oil of the pump 23 that drives the motor is switched. A pressure compensating spool 9 and a first throttle 11 are connected to the same circuit as the brake cylinder 4 through a connection port 15 and a variable opening 10. The opening of the variable opening 10 is changed by the movement of the pressure compensating spool 9 and communicates with the inner chamber 32 of the pressure compensating spool 9 and the first throttle 11. The first throttle 11 controls the flow rate of the pressure oil discharged from the brake cylinder 4 to the tank when braking the brake 20. The pressure compensating spool 9 is moved to a position where the variable opening 10 is narrowed so that the pressure difference of the pressure oil acting on the inner chamber 32 and the spring chamber 31 at both ends thereof is balanced with the elastic force of the pressure compensating spring 12. This is a conventionally known one in which the pressure difference before and after the first throttle 11 is made constant. further,
A piston 7 having a pressure compensating spring 12 sandwiched between the pressure compensating spool 9 and the spool 9 is disposed coaxially with the pressure compensating spool 9, and a piston 7 is provided between the back chamber 8 of the piston 7 and the downstream side of the first throttle 11. 2 apertures
29 are provided. Further, the switching valve 5 which has a spool connected to the spool of the main switching valve 2 and is switched has a brake cylinder 4 and a pressure compensating spool 9 at a pressure oil supply / discharge position where the main switching valve 2 drives the hydraulic motor 1. An oil passage for supplying pressure oil from the pilot pump 3 is connected to the oil passage communicating with the oil passage and the oil passage communicating with the back chamber 8 of the piston 7, and the second throttle 29 is provided downstream of the first throttle 11. Connection port 17 that merged downstream of
The oil passage communicating with the brake cylinder 4 and the pressure compensating spool 4 and the oil passage communicating with the back chamber 8 of the piston 7 are piloted at the neutral position of the main switching valve 2 while the passage between the tank and the tank is shut off. The pressure oil supply oil passage of the pump 3 is cut off, and the passage from the connection port 17 which joins the downstream of the first throttle 11 and the downstream of the second throttle 29 is connected to the tank.

The operation of the brake device for the hydraulic motor configured as above will be described. First, when the hydraulic motor 1 is driven, when the main switching valve 2 is operated to switch from the neutral position II to the switching position I in the figure, the oil discharged from the pump 23 passes through the oil passage 25 and is discharged from the hydraulic motor 1. Since the other side connection port is supplied to the side connection port and is connected to the tank via the oil passage 24 and the main switching valve 2, the hydraulic motor 1 tries to rotate in one direction. At the same time, the switching valve 5 connected to the main switching valve 2 also switches from the neutral position II to the switching position I, and the pressure oil of the pilot pump 3 is built in by the pressure oil that is supplied to the brake cylinder 4 via the switching valve 5 without delay. The output of the spring 22 is overcome to release the braking of the brake 20. Therefore, the hydraulic motor 1 is released from the braking state and starts rotating. At this time, the connection opening 15 and the variable opening 10 connected to the same circuit as the brake cylinder 4
The switching valve 5 cuts off the communication from the passage that joins the downstream side of the first throttle 11 communicating with the downstream side of the second throttle 29 from the connection port 16 through the back chamber 8 of the piston 7 to the downstream side of the second throttle 29. On the other hand, since the spring chamber 31 having the pressure compensation spring 12 is always connected to the tank, the pressure compensation spool 9 has its inner chamber.
The pressure oil of the pilot pump 3 acts on the valve 32 from the connection port 15 through the switching valve 5 and the variable opening 10 to move leftward to the position where the variable opening 10 is closed against the elastic force of the pressure compensation spring 12. , The pressure oil of the pilot pump 3 also acts on the back chamber 8 of the piston 7 from the connection port 16 via the switching valve 5 to move the piston 7 to the right end of the movable range, thereby maximizing the pressure compensation spring 12. Equilibrium will be maintained in the compressed state.

Next, when the driving of the hydraulic motor 1 is stopped, when the main switching valve 2 and the switching valve 5 connected thereto are returned to the neutral position II while the hydraulic motor 1 is rotating, the inertial load of the hydraulic motor 1 is reduced. Tries to continue rotating, but the pressure oil discharged from the hydraulic motor 1 is discharged to the oil passage 25 on the other side through the cross relief valve 34 because the oil passage 24 is closed by the main switching valve 2. Therefore, the hydraulic motor 1 is controlled by the pressure oil and starts deceleration. On the other hand, the switching valve 5 shuts off the supply of pressure oil from the pilot pump 3 to the brake cylinder 4 and connects the downstream side of the first throttle 11 from the connection port 17 to the tank, so that it is contained in the brake cylinder 4. The pressure oil is the connection port 15, the variable opening 10, the first throttle 11, the connection port 17
After that, the gas is discharged at a flow rate according to the opening of the first throttle 11 and the pressure difference before and after that, that is, the pressure difference between the inner chamber 32 of the pressure compensation spool 9 and the spring chamber 31 connected to the tank. At the initial stage of discharging, the pressure compensating spring 12 is compressed to the maximum and the pressure difference around the controlled first throttle 11 is high and the discharging speed is fast, but the switching valve 5 causes the pilot pump 3 to move to the back of the piston 7. As the supply of pressure oil to the chamber 8 is also cut off and gradually discharged through the second throttle 29, the piston 7 returns and retracts due to the elastic force of the pressure compensating spring 12 so that it is between the pressure compensating spool 9 and the piston 7. The elastic force of the pressure compensating spring 12 sandwiched between the first and second throttles 11 is reduced, and accordingly the pressure difference before and after the first throttle 11 and the discharge speed are reduced. In this way, in the initial process of discharging the pressure oil from the brake cylinder 4 that operates the brake 20 that brakes the output shaft 21 of the hydraulic motor 1, the discharge speed of the pressure oil changes momentarily, but from the start of discharge to the brake operation. The time is constant as long as there is no change in the opening area of the first diaphragm and the property of the pressure oil.

When the oil temperature decreases and the viscosity of the oil increases, on the other hand, the pressure oil discharged from the brake cylinder 4 becomes difficult to pass through the first throttle 11, which tends to delay the brake operation start timing. On the other hand, according to the present invention, on the other hand, since the pressure oil in the back chamber 8 of the piston 7 which has been cut off is increased in viscosity when passing through the second throttle 29, the discharge speed is reduced, so that the piston 7 is compressed by the pressure compensating spring 12. The degree to which the elastic force of the pressure compensating spring 12 is reduced by returning and retracting due to the elastic force of
The change in the discharge time, that is, the time until the brake is actuated will be extremely small, offsetting the degree of decrease in the pressure difference before and after the throttle 11 slowly.

When the main switching valve 2 is operated to switch to the switching position III, the description is omitted because it is the same as the above except that the rotation direction of the hydraulic motor 1 is reversed.

FIG. 2 shows a second embodiment of the present invention, in which the main switching valve 2 is controlled by connecting the pressure oil of the pilot pump 3 to both pilot connection ports of the main switching valve 2 by the pilot control valve 6. When the pilot control valve 6 is switched from the neutral position b to, for example, the switching position a, the pressure oil of the pilot pump 3 is supplied to one pilot connection port, and the main switching valve 2 and the switching valve 5 connected thereto are both moved to the switching position I. Since the same operation as that of the first embodiment is obtained, the pressure oil in the brake cylinder 4 passes through the inner chamber 32 of the pressure compensation spool 9 and the first throttle 11 provided in the pressure compensation spool 9. The configuration is the same as that of the first embodiment except that the downstream side is disconnected / connected from the connection port 17 to the tank by the switching valve 5, and the second throttle 29 is provided in the piston 7.

FIG. 3 is a third embodiment and will be described by showing only a part different from the case of the first embodiment shown in FIG. 1, in place of the pilot pump 3 in the first embodiment, from the pump 23 to the main switching valve. An oil passage 24 for supplying and discharging pressure oil for driving the hydraulic motor 1 via 2
・ Shuttle valve for pressure oil on the higher pressure side of 25
Selective extraction by 26 and switching valve 5 as pilot pressure oil
Connected to.

FIG. 4 shows the pressure compensation spool 9, the piston 7, and the first throttle.
11, 3rd with the second diaphragm 29 built into the case of the motor 1
The operation and effect of the embodiment are the same as those described above.

[Advantage of the Invention] In the operation of the mechanical brake used together with the brake device of the hydraulic motor, the flow rate of the pressure oil discharged from the brake cylinder to the tank for braking is controlled through the pressure-compensated throttle, and the pressure compensation spool is repressed. The pressure oil in the back chamber of the piston, which is biased to build up the elastic force on the spring, is gradually discharged to the tank through the second throttle to gradually reduce the elastic force, and after the stop operation of the motor, the pressure, It can be said that the pressure oil is effectively worked after a certain time regardless of the viscosity of the pressure oil. As a result, it is possible to reduce the size and weight of the brake, as well as prevent the load from deviating during the delay time of the brake operation when the oil temperature is low.

[Brief description of drawings]

FIG. 1 is a sectional view showing a part of the first embodiment of the present invention with a circuit symbol, FIG. 2 is a sectional view showing part of the second embodiment of the present invention with a circuit symbol, and FIG. FIG. 4 is a partial circuit diagram showing only a part of the third embodiment of the present invention different from the first embodiment, and FIG. 4 is a sectional view showing a fourth embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Hydraulic motor, 2 ... Main switching valve, 3 ... Pilot pump, 4 ... Brake cylinder, 5 ... Switching valve, 6 ... Pilot control valve, 7 ... Piston, 8 ... Back chamber, 9 ... Pressure compensation spool, 11 ... No. 1st throttle, 12 ... pressure compensation spring, 20 ... brake, 21 ... output shaft, 22 ... spring, 29 ... second throttle.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location G05D 16/16 P Judge's collegial body Judge General Minoru Kajizawa Jimi Takahashi Judge Judge Sakae Shinkai (56 ) References: Actually open 62-194172 (JP, U) Actually open 62-200803 (JP, U) Actual Kohei 7-3044 (JP, Y2)

Claims (5)

[Scope of utility model registration request] Claim: 1. Braking the output shaft (21) of the hydraulic motor (1)
Braking of the brake (20) by releasing the brake (20) and the built-in spring (22) to brake the brake (20) and to act against the output of the spring (22) by the pressure oil of the pilot pump (3). Brake cylinder (4)
A main switching valve (2) for switching the supply and discharge of pressure oil for driving the hydraulic motor (1), and a first throttle (11) for controlling the flow rate of pressure oil discharged from the brake cylinder (4) to the tank.
And a pressure compensating spool (9) for making the pressure difference before and after the first throttle (11) constant, in a hydraulic motor braking device, the pressure compensating spool (9) is provided coaxially with the pressure compensating spool (9). ) With a pressure compensation spring (12) sandwiched between the piston (7) and the back chamber (8) of the piston (7)
And a second throttle (29) provided between the first throttle (11) and the downstream of the first throttle (11), and a spool connected to the spool of the main switching valve (2) to switch the main switching valve (2). At the pressure oil supply / discharge position for driving the hydraulic motor (1), the oil passage communicating with the brake cylinder (4) and the pressure compensating spool (9) and the oil communicating with the back chamber (8) of the piston (7). The oil passage for supplying pressure oil from the pilot pump (3) is connected to the passage, and the downstream passage of the first throttle (11) and the tank are shut off, and the neutral valve of the main switching valve (2) is neutralized. In position,
The oil passage communicating with the brake cylinder (4) and the pressure compensation spool (9) and the oil passage communicating with the back chamber (8) of the piston (7) are cut off from the pressure oil supply oil passage of the pilot pump (3), A switching device (5) configured to connect the downstream passage of the first throttle (11) to the tank, and a brake device for a hydraulic motor. 2. A main control valve (2) is a pilot control valve (6).
The pilot pump (3) pressure oil to the main switching valve (2)
The hydraulic motor brake device according to claim 1, characterized in that the brake device is connected to both pilot connection ports for control. 3. A brake device for a hydraulic motor according to claim 1, wherein the first throttle (11) is incorporated in the pressure compensating spool (9). 4. A brake device for a hydraulic motor according to claim 1 or 2, wherein a second throttle (29) is incorporated in the piston (7). 5. The utility model registration claim 3 or 4 characterized in that the first throttle, the second throttle, the pressure compensating spool and the piston are built in a case of the hydraulic motor.
A brake device for a hydraulic motor according to the item.