JPH01255702A - Brake circuit for hydraulic motor - Google Patents

Abstract

PURPOSE:To surely prevent a hydraulic motor from malfunctioning, by providing a setting means for setting the hydraulic pressure discharged from a variable displacement pump to a predetermined pressure at which a brake release cylinder can be actuated, in a hydraulic circuit. CONSTITUTION:An unload valve 29 setting the discharge pressure of a variable displacement hydraulic pump 21 to a predetermined pressure at which a brake release cylinder 25 can be released is disposed between a discharge pipe from the variable displacement pump 21 and a tank. With this arrangement, a brake release cylinder 25 is operated to release a hydraulic motor 22 from its braking condition, and when a selector valve 23 is changed over, the predetermined pressure at which the brake release cylinder can be released is fed at once into the hydraulic motor 22, thereby it is possible to surely prevent the hydraulic motor from malfunctioning.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a brake circuit for a hydraulic motor provided in a hydraulic machine such as a hydraulic excavator.

<Prior Art> FIG. 9 is a circuit diagram showing an example of a conventional brake circuit for a hydraulic motor. In this FIG. 9, 1 is a hydraulic motor;
2 is a rotating shaft of this hydraulic motor 1, 3 is a brake release cylinder that constitutes a mechanical brake device that releases the brake of this rotating shaft 2, 4 is a hydraulic pump that discharges pressure oil to drive the hydraulic motor 1, and 5 is a hydraulic pressure. A directional control valve 8 is interposed between the motor 1 and the hydraulic pump 4 and switches the direction of pressure oil discharged from the hydraulic pump 4. Reference numeral 8 is a pilot operating valve that drives the directional control valve 5.

In this brake circuit, when the directional control valve 5 is in the neutral position A, the oil discharged from the pump 4 is discharged to the tank 7 via the pipe 4a, the suction port 5b, the discharge port 5f, and the pipe 7a. Ru.

Here, if the pilot operation valve 8 is operated in the W direction in FIG. 9, the pilot pressure of the pilot pump 8b enters the pilot pipe 8a from the suction/discharge port 8d via the pilot valve 8C, and then enters the pilot pipe 8a through the pipe 8g, Shuttle valve 8e,
It enters the cylinder chamber 3a of the brake release cylinder 3 through the discharge port 8h, the conduit 8f, and the check valve 10, and releases the braking of the rotating shaft 2 of the hydraulic motor 1 against the force of the spring 3b. Make it rotatable. Further, the pilot pressure guided to the pilot pipe 8a as described above enters the cylinder chamber 51 of the directional control valve 5, and thereby the directional control valve 5
is switched from the illustrated neutral position A to the C position. When the directional control valve 5 is switched in this way, the oil discharged from the hydraulic pump 4 is transferred to the pipe 4a, the pipe 4C1, the check valve 4b, the suction port 5a,
The oil is guided to the hydraulic motor 1 via the discharge port 5e, the pipe line 1a, and the suction/discharge port IC, and the return oil is guided through the suction/discharge port 1d, the pipe line 1b, the suction/discharge port 5g of the directional control valve 5, the discharge port 5C1, and the pipe line 7b. The oil is returned to the tank 7, thereby causing the hydraulic motor 1 to rotate.

Further, when the pilot operation valve 8 is returned to the neutral position from the above state, the pilot valve 8C communicates with the tank 7, thereby the pilot pipe line 8a communicates with the tank 7, and the cylinder chamber 51 of the directional control valve 5 opens. The directional control valve 5 is switched to the neutral position A in communication with the tank 7. At the same time, the pressure in the pipe i￥lf also decreases, so the brake release cylinder 3
The pressure in the cylinder chamber 3a also decreases, and the mechanical brake device is moved in the direction of braking the rotating shaft 2 of the hydraulic motor 1. However, the pressure oil in the cylinder chamber 3a is stopped by the check valve 10 and bypasses the pipe line 11, so the throttle valve 1
Pass through 2. That is, it takes time for the pressure in the cylinder chamber 3a to decrease, and during this time the directional control valve 5 closes the pipe line 1b.
The hydraulic motor 1 is stopped by applying a brake to the hydraulic motor 1, and then the rotating shaft 2 of the hydraulic motor 1 is locked (braked) by a mechanical brake device.

<Problems to be Solved by the Invention> The conventional brake circuit for the hydraulic motor described above is provided in, for example, a hydraulic excavator shown in FIG. 10. The hydraulic excavator shown in FIG. 10 is sometimes placed horizontally on a slope as shown in the figure when carrying out excavation work or the like.

In this case, gravity acts on the rotating body 14 to cause it to rotate in the direction indicated by the arrow. This turning force does not turn the rotating body 14 while the rotating shaft 2 of the hydraulic motor 1 is being braked by the brake release cylinder 3 shown in FIG.

In the state shown in FIG. 10, that is, in the neutral state of the pilot operated valve 8 shown in FIG. Not yet. Here, when operating the pilot operating valve 8 to turn the rotating body 14 in the direction opposite to the arrow in FIG. When the spool is released, the spool of the directional control valve 5 also begins to move, but at this time, a turning force against gravity is required to rotate the rotating body 14 in the direction opposite to the arrow in FIG. Therefore, the spool of the directional control valve 5 must be moved by a considerable amount to build up the pressure necessary for turning. In other words, the desired pressure will not be generated in the hydraulic pump 4 unless the suction port 5b of the directional control valve 5 is closed by a certain amount. During this period, the pressure inside the pipeline of the hydraulic motor 1 gradually rises to a holding pressure that can withstand the turning force due to the above-mentioned gravity. and,
The volume of oil decreases in accordance with the expansion of the rubber i-:z used for the piping of the hydraulic motor 1. This decrease results in
Although the intention is for the rotating body 14 to turn in the direction opposite to the arrow in FIG. A situation arises in which it rotates in the direction of the arrow. This is a movement contrary to the operating direction of the pilot pump 8, and gives a sense of discomfort to the operator. Furthermore, this is particularly dangerous when a load is suspended from the tip of a packet 13 of a hydraulic excavator as shown in FIG. 10, as it causes the load to swing.

The present invention has been made in view of the above-mentioned actual situation in the prior art, and its purpose is to reliably prevent malfunctions of the hydraulic motor based on the arrangement of the hydraulic machine equipped with the brake circuit of the hydraulic motor. Our objective is to provide a hydraulic motor brake circuit that can.

Means for Solving the Problems To achieve this object, the present invention includes a hydraulic pump, a hydraulic motor driven by pressure oil discharged from the hydraulic pump, and a hydraulic motor driven by pressure oil supplied from the hydraulic pump to the hydraulic motor. In a brake circuit for a hydraulic motor, the brake circuit includes a directional control valve that controls the flow of pressure oil, and a brake release cylinder that releases braking of a rotating shaft of the hydraulic motor in accordance with the supply of pressure oil.
The hydraulic pump is a variable displacement cedar hydraulic pump, and includes a control actuator that controls the displacement of the variable displacement expansion hydraulic pump, a flow rate adjustment valve with a pressure compensator that controls the drive of this control actuator, and a variable displacement hydraulic pump. The configuration includes a setting means for setting the pressure of the pressure oil discharged from the capacity expansion hydraulic pump to a predetermined pressure at which the brake release cylinder can be released, and a drive means for driving the brake release cylinder in accordance with the pressure oil. It's Nishide.

Since the present invention is configured as described above, when the brake of the hydraulic motor is released, the drive means can be operated to operate the brake release cylinder to release the brake of the hydraulic motor, and the directional control valve can also be operated. By switching, a predetermined pressure that can release the brake release cylinder set by the setting means of the drive means is immediately supplied to the hydraulic motor, that is, the influence of the reduction in the volume of the oil due to the compression of the oil and the expansion of the rubber hose is eliminated. Therefore, depending on the arrangement of the hydraulic machine equipped with the brake circuit of this hydraulic motor, even when a turning force due to an external force such as gravity is applied to the rotating shaft of the hydraulic motor, the above-mentioned predetermined pressure can be maintained. counteracts the above-mentioned turning force, thereby making it possible to rotate the hydraulic motor without causing the hydraulic motor to reverse, thereby reliably preventing malfunction of the hydraulic motor.

<Example> Hereinafter, a brake circuit for a hydraulic motor of the present invention will be explained based on the drawings.

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

In the first embodiment shown in FIG. 1, a variable displacement expansion hydraulic pump 21 is provided as a hydraulic pump, and a hydraulic motor 2 is driven by pressure oil discharged from this hydraulic pump 21.
2, a manually operated directional control valve 23 that controls the flow of pressure oil supplied from the hydraulic pump 21 to the hydraulic motor 22;
A brake release cylinder 25 is provided to release the brake on the rotating shaft 24 of the hydraulic motor 22. The brake release pressure of this brake release cylinder 25 is, for example, 10 kg7/C.
It is also equipped with a control actuator 26 that controls the displacement of the pump 21, and a flow rate adjustment valve 27 with a pressure compensator that controls the drive of this control actuator 26. The spring set pressure of the spring chamber 27a of the flow rate regulating valve 27 with a compensator is, for example, 1.
5 kg/cm".

In addition, it has a setting means for setting the pressure of the pressure oil discharged from the hydraulic pump 21 to a predetermined pressure at which the brake release cylinder 25 can be released, and the pressure oil discharged from the hydraulic pump 21 is A driving means 28 is provided for driving the brake release cylinder 25 accordingly.

This drive means 28 is provided as the above-mentioned setting means, and has a spring set pressure of 20 kg/cm2, for example, and an unload valve 29 interposed between the discharge pipe of the variable capacity expansion hydraulic pump 21 and the tank. and directional control valve 23
a throttle valve 30 built into the throttle valve 30; a first pipe line 31 connecting the secondary side of the throttle valve 30 with the spring chamber 27a of the pressure compensator-equipped flow rate adjustment valve 27; a check valve 32 that is interposed in the throttle valve 30 to prevent pressure oil from flowing back toward the throttle valve 30;
A small amount relief valve 34 allows a small amount of pressure oil flowing through the first pipe line 31 to flow into the tank 33, and a small amount relief valve 34 allows the pressure oil flowing through the first pipe line 31 to flow into the brake release cylinder 25.
a second pipe line 35 leading to the tank 33, a throttle valve 36 interposed in the first pipe line 31, a portion of the first pipe line 31 located between the throttle valve 36 and the spring chamber 27a, and a tank 33. The relief valve 37 is disposed between the throttle valve 36 and the spring chamber 27a to maintain a predetermined pressure in the pipe line between the throttle valve 36 and the spring chamber 27a.

In the first embodiment configured in this way, as shown in FIG. 1, when the directional control valve 23 is in the neutral position and the hydraulic pump 21 is being driven, the hydraulic pump 21 is
The discharge pipe line and the first pipe line 31 are cut off, and the first
Since the pipe line 31 communicates with the tank 33 via the small amount relief valve 34, the tank pressure is led to the brake release cylinder 25 via the second pipe line 35, and the rotation shaft 24 of the hydraulic motor 22 is maintained in a braking state. Further, the pressure oil discharged from the hydraulic pump 21 is guided to the cylinder chamber 27b of the flow rate adjustment valve 27, and the tank pressure is guided to the spring chamber 27a via the throttle valve 36.
The piston of the control actuator 26 moves to the right, the displacement of the hydraulic pump 21 is maintained at the minimum tilt position, and the minimum flow rate is discharged from this hydraulic pump 21. loaded. In addition,
The pressure of the pressure oil discharged from the hydraulic pump 21 by the unload valve 29 is maintained at 20 kg/cm2.

In such a state, when the direction control valve 23 is switched to the left or right with the intention of driving the hydraulic motor 22, the secondary side of the throttle valve 30 is communicated with the first pipe line 31, that is, the discharge of the hydraulic pump 21 is The conduit and the second conduit 35 communicate,
The pressure discharged from the hydraulic pump 21 is 20 kg/
Pressure oil with a pressure of more than cm" is applied to the throttle valve 30 of the directional control valve 23,
It is led to the brake release cylinder 25 through the first pipe line 31, the check valve 32, and the second pipe line 35, and the brake release pressure of the brake release cylinder 25 is 10 kg/c.
m2, the brake release cylinder 25 immediately operates to release the brake on the rotating shaft 24 of the hydraulic motor 22. At this time, as described above, the direction control valve 23
Since the secondary side of the throttle valve 30 communicates with the first pipe line 31, a gradually rising pressure is introduced into the spring chamber 27a of the flow rate regulating valve 27 via the throttle valve 36, and this rising pressure and the spring When the resultant force with the spring force of the chamber 27a becomes larger than the pressure on the cylinder chamber 27b side, that is, the pressure discharged from the hydraulic pump 21, the flow rate regulating valve 27 is gradually switched to the right position, and the head of the control actuator 26 is The side chamber communicates with the tank 33, its piston moves to the left, the displacement volume of the hydraulic pump 21 increases, and a large flow rate flows through the directional control valve 23 to the hydraulic motor 22.
The rotating shaft 24 of this hydraulic motor 22 rotates.

Furthermore, when the directional control valve 23 is returned to the neutral position with the intention of braking the hydraulic motor 22 in the rotating state, the directional control valve 23 connects the discharge pipe of the hydraulic pump 21 and the hydraulic motor 2.
At the same time, communication between the discharge pipe line of the hydraulic pump 21 and the first pipe line 31 is cut off by the directional control valve 23. At this time, although the rotation of the hydraulic motor 22 is stopped due to the neutral return of the direction control valve 23,
The pressure in the first conduit 31 is transferred from the trace relief valve 34 to the tank 3.
3.It decreases little by little according to the pressure oil that gradually escapes, so
The brake release operation of the brake release cylinder 25 is delayed a little, so the brake release cylinder 25 brakes the rotating shaft 24 after the hydraulic motor 22 stops rotating.

Furthermore, if the hydraulic motor 22 is turned by an external force while it is rotating, the hydraulic motor 22 may perform a pumping action and the pressure on the secondary side of the throttle valve 30 may drop. Since the backflow of the pressure oil is stopped by the check valve 32, the pressure in the second pipe line 35 will not drop suddenly, that is, the brake release cylinder 25 will not perform a sudden braking operation. .

Assume that this first embodiment is installed in, for example, a hydraulic excavator illustrated in FIG. 10, and that the hydraulic excavator is placed sideways on a slope as shown in FIG.
When a force is applied to the rotating body 14 in the direction shown by the arrow, the operator switches the directional control valve 23 shown in FIG. 1 from the neutral state to rotate the rotating body 14 in the direction opposite to the arrow in FIG. When attempting to do so, the pressure of the pressure oil discharged from the hydraulic pump 21 shown in FIG. As the valve 23 is switched, the brake release cylinder 25 releases the brake, and this pressure oil with a pressure of 20 kg/cm" or more is immediately supplied to the hydraulic motor 22. That is, in the direction of the arrow shown in FIG. Pressure oil with a pressure of 20 kg/r m2 or more is supplied to the hydraulic motor 22 as a holding force to counter the force of turning the motor, and therefore, the oil capacity is reduced due to compression of the oil or expansion of the rubber hose. The hydraulic motor 22 is not affected by the above-mentioned turning force in the direction indicated by the arrow in FIG.
Even in such a situation on a slope, the revolving body 14 can be immediately turned in the direction opposite to the desired arrow in FIG. If this is done, work safety can be ensured without causing load swing.

Fig. 2 is a circuit diagram showing a second embodiment of the invention, Fig. 3 is a circuit diagram showing a third embodiment of the invention, and Fig. 4 is a circuit diagram showing a fourth embodiment of the invention. be.

In the second embodiment shown in FIG. It is configured to have a pressure reducing valve 38 inside. The other basic configuration is the same as that of the first embodiment shown in FIG.

In the second embodiment configured in this way, the maximum pressure applied to the brake release cylinder 25 can be limited, which provides the same effect as the first embodiment described above. The withstand voltage can be set low.

A third embodiment, shown in FIG. Selective connection switching valve 4
0, and further includes a throttle valve 42 and a check valve 43 in parallel in a pipe 41 portion that communicates the brake release cylinder 25 and the switching valve 40. The other basic configuration is the same as that of the first embodiment shown in FIG.

In this third embodiment, when the directional control valve 23 is switched, the discharge pressure of the hydraulic pump 21 is changed to the first pipe line 31,
It is supplied to the driving part of the switching valve 40 through the second pipe line 35, whereby the switching valve 40 is switched to the lower position shown in the figure, and the brake release cylinder 25 and the three pilot hydraulic pressure sources are communicated. Therefore, the pilot pressure from the three pilot hydraulic pressure sources is applied as a release pressure to the brake release cylinder 25 via the switching valve 40, the pipe line 41, and the check valve 43, and the braking of the rotating shaft 24 of the hydraulic motor 22 is released.

Moreover, when the direction control valve 23 returns to neutral, the hydraulic pump 2
Since the first discharge pipe line and the first pipe line 31 are cut off, the second pipe line 35 becomes tank pressure, the switching valve 40 is switched to the upper position shown in FIG. 3, and the brake release cylinder 25 and tank 33 communicate with each other. At this time, the pipe line 41
Since the throttle valve 42 is provided in the brake release cylinder 25, the brake release cylinder 25 gradually lowers to the tank pressure, that is, after the hydraulic motor 22 stops, the rotary shaft 24 is braked.

This third embodiment also achieves the same effects as the first embodiment described above, and also provides the maximum amount applied to the brake release cylinder 25 by setting the pilot pressure of the pilot hydraulic pressure source 39 relatively low. High pressure can be limited, and thereby the withstand pressure of the brake release cylinder 25 can be set low.

In the fourth embodiment shown in FIG. 4, the drive means 28 includes a third pipe 44 communicating the hydraulic pump 21 and the directional control valve 23, and is also connected to a second pipe 35 to release the brake. Cylinder 25, the above-mentioned third pipe line 44 and tank 3
3, including a switching valve 40 that selectively connects the
Furthermore, a pressure reducing valve 38 is interposed in the third pipe line 44, and a throttle valve 42 and a check valve 43 are installed in parallel in the pipe line 41 section that communicates the brake release cylinder 25 and the switching valve 40. It is configured to include.

In this fourth embodiment, when the directional control valve 23 is switched, the discharge pressure of the hydraulic pump 21 is changed to the first pipe line 31,
It is supplied to the driving part of the switching valve 40 through the second pipe line 35, whereby the switching valve 40 is switched to the lower position shown in the figure, and the brake release cylinder 25 and the third pipe line 44 are communicated with each other. At this time, the pressure of the pressure oil led from the hydraulic pump 21 through the third pipe line 44 is reduced by the pressure reducing valve 38, and this reduced pressure oil passes through the switching valve 40, the pipe line 41, and the check valve 43. It is guided to the brake release cylinder 25 through the brake release cylinder 25, and the brake release cylinder 25 is driven to rotate the rotation shaft 24 of the hydraulic motor 22.
The brake is released. Furthermore, when the direction control valve 23 returns to neutral, the discharge line of the hydraulic pump 21 and the first line 31 are cut off, so the second line 35 becomes tank pressure.
The switching valve 40 is switched to the upper position shown in FIG. 4, and the brake release cylinder 25 and the tank 33 are communicated with each other. As a result, the brake release cylinder 25 gradually descends to the tank pressure, and after the hydraulic motor 22 stops, its rotating shaft 24
brake.

This fourth embodiment also has the same effects as the first embodiment described above, and the pressure reducing valve 38 can limit the maximum pressure applied to the brake release cylinder 25. The withstand voltage can be set low.

FIG. 5 is a circuit diagram showing a fifth embodiment of the present invention.

In the fifth embodiment, a directional control valve 45 interposed between a hydraulic pump 21 and a hydraulic motor 22 has main valves 46 and 47 disposed in a meter-in circuit and main valves 48 and 47 disposed in a meter-out circuit. It has a plurality of main valves including 4 main valves (4-), and when each of the main valves 46 to 4 is closed, a maximum throttle state is formed, and as the opening degree of the main valves 46 to 49 increases, the throttle becomes larger. The slits 50, 51, 52, and 53 form variable apertures that reduce the amount, and the slits 50 to 5
3 and the pilot valve 54 that operates the main valves 46 to 49'.
．． 55, 56, and 57 logic valves. Note that, for example, the slit 50 on the main valve 46 side is
In the state shown in the figure, that is, the state in which the main valve 46 is closed, it opens slightly to the back pressure chamber 46a side, thereby creating a maximum throttle state, and the main valve 46 opens to connect the pump port 64 and the outflow port. The slit 5 communicates with the main valve 46 and is exposed to the back pressure chamber 46a when the opening degree of the main valve 46 increases.
The aperture amount at 0 becomes larger and the aperture amount is reduced. This means that each slit 51 of the main valve 47, 48, 49
．． The same applies to the variable aperture formed by 52.53.

In this fifth embodiment, the driving means 28 includes two unload valves provided as setting means, an outflow port 58, 59 of the main valve 46, 47 disposed in the meter-in circuit, and a spring chamber of the flow rate regulating valve 27. 27a, and a check valve 6 interposed in the fourth pipe line 60 to prevent backflow of pressure oil in the five directions of the outflow port 58.
1.62, a trace relief valve 34 that allows a trace amount of pressure oil flowing through the fourth pipe line 60 portion connecting these check valves 61, 62 and the above-mentioned spring chamber 27a to flow into the tank 33, and a fourth Pressure oil in the pipe line 60 of the brake release cylinder 2
5, and a fifth conduit 63 leading to the release of the fifth conduit 63. The configuration of the pond is the same as the first embodiment shown in FIG.

As described above, in the fifth embodiment in which the direction control valve 45 is constituted by a logic valve having four main valves 46 to 49, when each pilot valve 54 to 57 is not operated, each of the main valves 46 to 4 one is kept in a closed state, the hydraulic pump 21 and the hydraulic motor 22 are cut off, and the hydraulic pump 21 and the fourth pipe 60 are cut off, and the hydraulic motor 22 stops rotating, and Brake release cylinder 2
5 includes a small amount relief valve 34, a fourth pipe line 60, and a fifth pipe line 6.
3, the tank pressure is introduced to brake the rotary shaft 24 of the hydraulic motor 22.

In such a state, for example, if the pilot valves 54 and 57 are operated, each pilot valve 54.
The main valve 16.49 opens by an amount proportional to the operation amount of 57, and the pressure oil discharged from the hydraulic pump 21 flows into the pump port 6.
4 to the outflow port 58, and this pressure oil is further led to the brake release cylinder 25 via the fourth pipe line 60 and the fifth pipe line 63 via the check valve 61, and the rotation shaft of the hydraulic motor 22. 24 is released. Further, the pressure oil led to the above-mentioned outflow bow 1-58 is supplied to one bow 1 of the hydraulic motor 22, and the return oil from the other port is supplied to the main valve 1-58.
It is led from the inflow port 65 on one side to the tank port 66, so that the hydraulic motor 22 starts rotating in one direction after the brake on the rotating shaft 24 is released.

Then, from this state, pilot valve 5.1.5
7 are returned to neutral, the space between the pump port 64 and the outflow port 58 on the main valve 46 side is closed, and the space between the inflow port 65 and the tank port 66 on the main valve 4 side is closed. Rotation stops. Further, as the space between the pump port 64 and the outflow port 58 is closed, the discharge pipe line of the hydraulic pump 21 and the fourth pipe line 60 are cut off, but v;9. By means of the volume relief valve 34 the fourth line 60 is gradually lowered to the tank pressure and thus the fifth line 63
The pressure led to the brake release cylinder 25 via the brake release cylinder 25 gradually decreases to the tank pressure, and after the hydraulic motor 22 stops, its rotating shaft 24 is braked by the brake release cylinder 25.

Furthermore, when the pilot valves 55 and 56 are operated from the neutral state in which the four main valves 46 to 49 are closed, the braking of the rotating shaft 24 is released in the same manner as described above, and the hydraulic motor 22 is activated in the opposite direction. Rotate in the direction.

Even in the fifth embodiment configured as described above, when the direction control valve 45 is in the neutral state, the pressure in the discharge line of the hydraulic pump 21 is set to 20 kg/cm2 by the unload valve 29. With the operation of the valve 54 or the pilot valve 55, a pressure of 20 kg/crn'' or more can be immediately supplied to the brake release cylinder 25, and the above-mentioned first
It has the same effect as the embodiment.

FIG. 6 is a circuit diagram showing a sixth embodiment of the present invention.

The embodiment shown in FIG. 6 is installed in a hydraulic excavator, and in this embodiment as well, a variable capacity expansion hydraulic pump 21 is provided as a hydraulic pump, and the brake release pressure is, for example, 10 kg/cm. A brake release cylinder 25 is provided which is set to ``.

Also, a control actuator 26 that controls the displacement of the hydraulic pump 21, and a control actuator 26 that controls the displacement of the hydraulic pump 21.
A pressure compensator-equipped flow rate adjustment valve 27 is provided to control the drive of the pressure compensator. The spring set pressure of the spring chamber 27a of the flow rate regulating valve 27 is set to, for example, 15 kg/cm2.

The hydraulic motors include a swing hydraulic motor 67, a left travel hydraulic motor 68, and a right travel hydraulic motor 69, and also includes a front attachment hydraulic cylinder 70 for driving a boom, arm, baguette, etc. . Further, in correspondence with each drive actuator of the swing hydraulic motor 67, left travel hydraulic motor 68, right travel hydraulic motor 69, and front attachment hydraulic cylinder 70, each drive actuator is connected to the hydraulic pump 21. A plurality of directional control valves that control the flow of pressure oil supplied to each of the directional control valves 71, 71 for turning, directional control valve 72 for left running, directional control valve 73 for left running, and directional control valve 74 for front attachment. It is equipped with The brake release cylinder 25 described above is connected to a swing hydraulic motor 67.
The braking of the rotating shaft 75 is released.

Further, the driving means 2 for driving the brake release cylinder 25
8 is provided as a setting means, and the set pressure is 2.Okg/
cm” unload valve 29 and swing direction control valve 7
1. A throttle valve 76 included in the front attachment direction control valve 74 and a brake release cylinder 2 for releasing the brake by merging the pressure oil on the secondary side of these throttle valves 76.
5, a first check valve 78 that is interposed in the sixth pipe line 77 and prevents the pressure oil from flowing back in the direction of the throttle valve 76, and A seventh connecting pipe 77 and the spring chamber 27a of the pressure compensator-equipped flow rate regulating valve 24 are connected to each other.
It is provided between the connection point 80 of the sixth pipe line 77 and the seventh pipe #r79, and the first check valve 78, and prevents pressure oil from flowing back toward the brake release cylinder 25. It includes a second check valve 81 and a minute release valve 82 that releases a minute amount of pressure oil flowing through the sixth pipe line 77 to the tank 33.

Note that the seventh conduit 79 described above includes this seventh conduit 79.
A small amount relief valve 34 that allows a small amount of pressure oil flowing through the valve 9 to flow out into the tank, a throttle valve 36 provided between this small amount relief valve 34 and the spring chamber 27a of the flow rate adjustment valve 27,
A relief valve 37 is provided to maintain a constant pressure in the pipeline between the spring chamber 27a and the spring chamber 27a.

The left-hand direction control valve 72 and right-hand direction control valve 73 described above also have throttle valves 83 built in, and the secondary sides of these throttle valves 83 are merged and connected to the connection point 80 described above. An eighth pipe line 84 to be connected, a check valve 85 interposed in the eighth pipe line 84 to prevent backflow of pressure oil toward the throttle valve 83, and these check valves 85. Connection point 8
Another check valve 86 is provided, which is connected between the check valve 85 and the check valve 85 to prevent pressure oil from flowing back in the direction of the check valve 85.

In the sixth embodiment configured in this manner, as shown in FIG. 6, when the directional control valves 71 to 74 are in the neutral position and the hydraulic pump 21 is driven, the hydraulic pump 21 and the sixth conduit 77 are cut off, and the sixth
Since the conduit 77 communicates with the tank via the small amount relief valve 82, the tank pressure is led to the brake release cylinder 25 via the sixth conduit 77, and the hydraulic motor 67 for turning
The rotating shaft 75 of is maintained in a braked state. Further, the flow rate regulating valve 27 is held at the left position as shown in FIG. , its discharge pressure is kept at 20 kg/cm2 by two unload valves.

In such a state, when the swing direction control valve 71 is switched to either the left or right side, the secondary side of the throttle valve 76 of the swing direction control valve 71 communicates with the sixth pipe line 77, that is, the hydraulic pump 21 The discharge pipe line and the sixth pipe line 77 communicate with each other, and the pressure discharged from the hydraulic pump 21 is 20 kg /
Pressure oil of cm2 or more is guided to the brake release cylinder 25 via the throttle valve 76 of the swing direction control valve 71, the sixth pipe line 77, and the first check valve 78, and the pressure oil of the brake release cylinder 25 is Brake release pressure is 10 kg/c
m2, the brake release cylinder 25 immediately operates to release the brake on the rotating shaft 75 of the turning hydraulic motor 67. At this time, a gradually rising pressure is introduced into the spring chamber 27a of the flow rate adjustment valve 27 via the throttle valve 36 of the seventh line 79 communicating with the sixth line 77, and as a result, the flow rate adjustment valve 27 is The control actuator 26 is gradually switched to the right position, the head side chamber of the control actuator 26 communicates with the tank 33, the piston moves to the left, the displacement of the hydraulic pump 21 increases, and a large flow rate flows through the swing direction control valve 71. The rotation hydraulic motor 6.7 is supplied via the hydraulic motor 6.7.

That is, after the brake on the rotating shaft 75 of the swing hydraulic motor 67 is released by the operation of the brake release cylinder 25,
Rotation of the turning hydraulic motor 67 begins.

Further, when the swing direction control valve 71 is returned to the neutral position with the intention of braking the swing hydraulic motor 67 in the rotating state, the communication between the hydraulic pump 21 and the sixth pipe line 77 is cut off. At this time, although the rotation of the swing hydraulic motor 67 is stopped due to the neutral return of the swing direction control valve 71, the pressure in the sixth pipe 77 is increased according to the pressure oil that gradually escapes from the trace relief valve 82 to the tank. The brake release action of the brake release cylinder 25 is slightly delayed, and this causes the brake release cylinder 25 to release the brake after the hydraulic motor 22 has stopped rotating.
Braking of the rotating shaft 75 is performed by the rotation shaft 75.

Note that even if the turning hydraulic motor 22 is rotated by an external force, the first check valve 78 prevents the pressure oil from flowing backward, and therefore the pressure in the sixth pipe line 77 is reduced. Brake release cylinder 25 without dropping suddenly
does not perform sudden braking action.

Furthermore, from the neutral state of each of the directional control valves 71 to 74 shown in FIG. When attempting to perform a multi-key operation with travel, the secondary side of the throttle valve 76 of the relevant front attachment directional control valve 74 communicates with the sixth pipe 77, and the left travel directional control valve 72 and the right travel Directional control valve 73
The secondary side of the throttle valve 83 communicates with the eighth pipe line 84, and the combined pressure oil flows through the seventh pipe line 79 to the mix valve 2.
The piston of the actuator 26 for control (1) moves to the left to increase the displacement volume of the hydraulic pump 21, and
The brake release cylinder 25 is actuated by the pressure oil guided to the sixth pipe line 77, and the rotation shaft 75 of the swing hydraulic motor 67 is activated.
is braked or released.

However, if you want to run by switching only the left travel direction control valve 72 and the right travel direction control valve 73, the throttle valve 83 of each direction control valve 72, 73
The pressure oil in the eighth pipe line 84 that communicates with Since the pressure oil is prevented from flowing in the direction of the pipe line 77 of No. 6, tank pressure is guided to the brake release cylinder 25.
The rotating shaft 75 of the swing hydraulic motor 67 is held in a braked state by the brake release cylinder 25.

That is, when the front attachment directional control valve 74 is switched, the braking of the rotating shaft 75 of the swing hydraulic motor 67 by the brake release cylinder 25 is released;
When only the left travel direction control valve 72 and the right travel direction control valve 73 are switched, the rotating shaft 75 is maintained in a braking state.

Even in the sixth embodiment configured in this way, when the rotating body 14 is placed horizontally on a slope as shown in FIG.
When the turning direction i control valve 71 is switched from the neutral position, pressure oil with a pressure set in advance to 20 kg/cm" or more is supplied from the hydraulic pump 21 to the brake release cylinder 25. The rotating body 14 can be immediately turned in the direction opposite to the arrow in the figure without causing any discomfort.

Furthermore, when using the front attachment during normal excavation work, etc., the brake on the rotating shaft 75 of the swing hydraulic motor 67 is released, so that the swing oil 1 pressure is reduced by the external force during the excavation work. Even when the motor 67 is about to rotate, it is allowed to rotate slightly, so that damage to the speed reducer and the like connected to the rotating shaft 75 of the swing hydraulic motor 67 can be prevented.

FIG. 7 is a circuit diagram showing a seventh embodiment of the invention, and FIG. 8 is a circuit diagram showing an eighth embodiment of the invention.

In the seventh embodiment shown in FIG. 7, the drive means 28 has a pressure reducing valve 87 in the sixth pipe line 77. Other basic configurations are the same as the sixth embodiment shown in FIG.

In the seventh embodiment configured in this way, in addition to achieving the same effects as the above-mentioned sixth embodiment, the maximum pressure applied to the brake release cylinder 25 can be limited, and thereby the brake release cylinder 25 The withstand voltage can be set low.

In an eighth embodiment shown in FIG. 8, the drive means 28 includes a pilot hydraulic pressure source 88 and the brake release cylinder 2
5, a switching valve 89 that selectively connects the pilot hydraulic power source 88 and the tank 33, and further communicates the brake release cylinder 25 and the switching valve 89.
The configuration includes a throttle valve 91 and a check valve 92 in parallel.

In this eighth embodiment, when the swing direction control valve 71 is switched, the discharge pressure of the hydraulic pump 21 is supplied to the driving parts of the eight switching valves through the sixth pipe line 77, thereby The eight switching valves are switched to the right position in FIG. 8, and the brake release cylinder 25 and the pilot hydraulic pressure source 88 are communicated. Therefore, the pilot pressure of the pilot oil pressure source 88 is applied as a release pressure to the brake release cylinder 25 via the switching valve 89, the pipe line 90, and the check valve 92, and the braking of the rotating shaft 75 of the swing motor 67 is released. .

When the turning direction control valve 71 returns to neutral, the sixth pipe line 77 becomes tank pressure, the switching valve 8 is switched to the left position in FIG. 8, and the brake release cylinder 25 and tank 33 are connected. It goes through. At this time, since the throttle valve 91 is provided in the conduit 90, the brake release cylinder 25 gradually lowers to the tank pressure, that is, after the swing hydraulic motor 67 stops, its rotating shaft 75 is braked.

This eighth embodiment also has the same effects as the sixth embodiment described above, and also limits the maximum pressure applied to the brake release cylinder 25 by lowering the pilot pressure of the pilot hydraulic pressure source 88. This allows the pressure resistance of the brake release cylinder 25 to be set low.

<Effects of the Invention> Since the hydraulic motor brake circuit of the present invention is configured as described above, it is possible to reliably prevent malfunctions of the hydraulic motor based on the layout of the hydraulic machine equipped with the hydraulic motor brake circuit. Therefore, it is possible to ensure the safety of work carried out with a hydraulic machine equipped with this hydraulic motor brake circuit without causing any discomfort in operation as in the conventional case.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a first embodiment of a brake circuit for a hydraulic motor of the present invention, Fig. 2 is a circuit diagram showing a second embodiment of the invention, and Fig. 3 is a circuit diagram showing a third embodiment of the brake circuit of the present invention. 4 is a circuit diagram showing a fourth embodiment of the present invention, FIG. 5 is a circuit diagram showing a fifth embodiment of the present invention, and FIG. 6 is a circuit diagram showing a sixth embodiment of the present invention. 7 is a circuit diagram showing a seventh embodiment of the present invention, FIG. 8 is a circuit diagram showing an eighth embodiment of the present invention, and FIG. 9 is a circuit diagram showing a conventional hydraulic motor. FIG. 10 is a perspective view showing an example of a working mode in a hydraulic excavator equipped with a brake circuit for a hydraulic motor. 21...Hydraulic pump, 22...Hydraulic motor, 23...Directional control valve, 24...
Rotating shaft, 25... Brake release cylinder, 2゛6... Control actuator, 27...
・Flow i adjustment valve with pressure compensator, 27a... Spring chamber, 28... Drive shaft, 2... Unload valve, 30... Throttle Valve, 31...
・First pipe line, 32...Check valve, 33...
...Tank, 34...Minor relief valve, 35...
...Second pipe line, 38...Pressure reducing valve, three...
...Pilot hydraulic power source, 40...Switching valve,
44... Third pipe line, 45... Directional control valve, 46.47.48.49... Main valve, 50
．． 51.52.53...Slit, 54.55
．． 56.57... Pilot valve, 58.5 pieces.
...Outflow port, 60...Fourth conduit,
61.62...Check valve, 63...5th
Pipe line, 67... Hydraulic motor for swing, 68...
... Hydraulic motor for left travel, 69 ... Hydraulic motor for right travel, 70 ... Hydraulic cylinder for front attachment, 71 ... Direction control valve for turning, 72 ...Left travel direction control valve, 73...
... Directional control valve for right travel, 74 ... Directional control valve for front attachment, 75 ... Rotating shaft,
76... Throttle valve, 77... Sixth pipe line, 78... First check valve, 79... Seventh pipe line, 80... Connection point, 81...
Second check valve, 82...Minor relief valve, 8'7.
...Pressure reducing valve, 88...Pylon) Hydraulic power source, 8...Switching valves. Fig. 1 Fig. 2 Fig. 425 No. 1 Yohe 33 38 Hemp presser Fig. 3 Otsu) 39 Pilot 2 pressure,), 4
0 Ninto Committee 4th Figure j/ 1 LL + 38 Creation ξ 33 40 vJ Juben 44 Taku 3
Noon1shi 5fim 45 Direction control p# Figure 6 Figure 7 jj 33 Figure 8 R Figure 9 W Nooooo ＼ Figure 10

Claims (1)

[Claims] (1) A hydraulic pump, a hydraulic motor driven by pressure oil discharged from the hydraulic pump, and a direction for controlling the flow of the pressure oil supplied from the hydraulic pump to the hydraulic motor. In a brake circuit for a hydraulic motor, which includes a control valve and a brake release cylinder that releases braking on a rotating shaft of the hydraulic motor in accordance with the supply of pressure oil, the hydraulic pump is a variable displacement hydraulic pump, and the hydraulic pump is a variable displacement hydraulic pump. a control actuator that controls the displacement of the displacement hydraulic pump;
A flow rate adjustment valve with a pressure compensator is provided to control the drive of the control actuator, and the pressure of the pressure oil discharged from the variable displacement hydraulic pump is set to a predetermined pressure capable of releasing the brake release cylinder. A brake circuit for a hydraulic motor, comprising a setting means and a driving means for driving the brake release cylinder according to the pressure oil. (2) The driving means communicates the unload valve provided as the setting means, the throttle valve built into the directional control valve, and the secondary side of the throttle valve and the spring chamber of the flow rate regulating valve with pressure compensator. a first pipe line; a check valve interposed in the first pipe line to prevent pressure oil from flowing back toward the throttle valve; and a check valve that communicates the check valve with the spring chamber. A small amount relief valve that allows a small amount of pressure oil flowing through the first pipe section to flow out to a tank, and a second pipe line that directs the pressure oil flowing through the first pipe section for release of the brake release cylinder. A brake circuit for a hydraulic motor according to claim 1, characterized in that: (3) The brake circuit for a hydraulic motor according to claim (2), wherein the drive means includes a pressure reducing valve provided in the second pipe line. (4) The driving means includes a pilot hydraulic pressure source and a switching valve that is connected to the second pipe line and selectively connects the brake release cylinder to either the pilot hydraulic pressure source or the tank. Claim (2)
Brake circuit of the hydraulic motor described. (5) The driving means includes a third pipe line communicating with the pipe line connecting the variable displacement hydraulic pump and the directional control valve, and is connected to the second pipe line, and includes a brake release cylinder;
3. The brake circuit for a hydraulic motor according to claim 2, further comprising a switching valve for selectively connecting either the third pipe line or the tank. (6) The directional control valve has a plurality of main valves including a main valve arranged in a meter-in circuit, and when these main valves are closed, a maximum throttle state is formed, and as the opening degree of the main valve increases, 2. A brake circuit for a hydraulic motor according to claim 1, comprising a logic valve having a variable throttle that reduces the amount of throttle and a pilot valve that operates the variable throttle and the main valve. (7) a fourth pipe line in which the driving means communicates an unload valve provided as a setting means, an outflow port of a main valve disposed in the meter-in circuit, and a spring chamber of a flow rate regulating valve with a pressure compensator; A check valve that is interposed in the fourth pipe line and prevents the pressure oil from flowing back toward the outflow port, and a fourth check valve that communicates between the check valve and the spring chamber.
a minute relief valve that allows a small amount of pressure oil flowing through the pipe section to flow out into a tank; and a fifth pipe line that guides the pressure oil in the fourth pipe section for release of the brake release cylinder. The brake circuit for a hydraulic motor according to claim 6, characterized in that: (8) The hydraulic motor includes a swing hydraulic motor, a left travel hydraulic motor, and a right travel hydraulic motor, and is equipped with a front attachment hydraulic cylinder, and these swing hydraulic motors, left travel hydraulic motors, A plurality of pumps are provided corresponding to the drive actuators of the right travel hydraulic motor and the front attachment hydraulic cylinder, and control the flow of pressure oil supplied from the variable displacement hydraulic pump to each drive actuator. 2. The hydraulic motor brake circuit according to claim 1, further comprising a directional control valve, wherein the brake release cylinder releases the brake on the rotating shaft of the swing hydraulic motor. (9) The drive means includes an unload valve provided as a setting means, and a throttle valve included in the direction control valve related to the swing hydraulic motor and the front attachment hydraulic cylinder;
There is a sixth pipe line which joins the pressure oil on the secondary side of these throttle valves and leads it to a brake release cylinder for releasing the brake, and a sixth pipe line is installed in this sixth pipe line to supply pressure in the direction of each of the throttle valves. a first check valve that prevents backflow of oil; and a seventh check valve that connects the sixth pipe line and the spring chamber of the flow rate regulating valve with a pressure compensator.
a second pipe provided between the connection point of the sixth pipe and the seventh pipe and the first check valve to prevent backflow of pressure oil toward the brake release cylinder. 9. The brake circuit for a hydraulic motor according to claim 8, further comprising a check valve and a minute relief valve that allows a minute amount of pressure oil flowing through the sixth pipe line to flow out into a tank. (10) The brake circuit for a hydraulic motor according to claim 9, wherein the drive means includes a pressure reducing valve provided in the sixth pipe line. (11) The driving means includes a pilot hydraulic pressure source, is connected to the sixth conduit, and has a brake release cylinder;
10. The brake circuit for a hydraulic motor according to claim 9, further comprising a switching valve for selectively connecting either the pilot hydraulic pressure source or the tank.