JPH0988904A - Hydraulic motor with brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the damage of a brake device in the case of the generation of drain surge at the time of starting a hydraulic motor as a result of being charged with sudden brake force at the time of stop of the hydraulic motor. SOLUTION: This device is constituted to control flow of pressurized oil flowing in a brake release passage 52 through a small oriffice 55 which is provided in the way of the brake release passage 52 for leading pressurized oil to a oil chamber 38 of a brake device 33. Braking of a hydraulic motor can, therefor, be gradually released by gradually supplying the pressurized oil to the oil chamber 38 of the brake device 33 owing to a given oriffice effect led to the oil chamber 38 at the time of starting the hydraulic motor. As a result, the generation of drain surge can be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic motor having a brake device which is preferably used for a traveling hydraulic motor of a hydraulic excavator, a turning hydraulic motor, a rope winch hydraulic motor, and the like.

[0002]

2. Description of the Related Art Generally, in a machine such as a hydraulic excavator or a hydraulic crane that drives an inertial body by using a hydraulic motor, a negative type brake device for applying a braking force to the hydraulic motor is usually provided. The brake device is configured to apply a braking force to the output shaft of the hydraulic motor when the hydraulic motor is stopped.

Therefore, FIG. 5 shows an example of a traveling hydraulic circuit of a hydraulic excavator as an example of a hydraulic motor with a brake device according to this type of prior art.

In FIG. 1, reference numeral 1 denotes a traveling hydraulic motor provided on a lower traveling body (not shown) of the hydraulic excavator. The hydraulic motor 1 drives a load such as a hydraulic excavator (hereinafter referred to as a vehicle) to travel. Therefore, the output shaft 1A is connected to the driving wheels (not shown) for traveling through the reduction gear. Further, the hydraulic motor 1 includes a brake device 17 described later.
The brake device 17 is configured to apply a braking force to the output shaft 1A of the hydraulic motor 1 as a parking brake when the vehicle is stopped.

Reference numeral 2 denotes a hydraulic pump which constitutes a hydraulic source together with the tank 3. The hydraulic pump 2 and the tank 3 are connected to the hydraulic motor 1 via a pair of main lines 4A and 4B, and are connected to the main lines 4A and 4B. A direction switching valve 5 is provided on the way. The direction switching valve 5 is switched from the neutral position (a) to the switching positions (b) and (c) by the operator manually operating the operation lever 5A, and the hydraulic pressure is changed at the switching positions (b) and (c). The direction of the pressure oil supplied and discharged from the pump 2 to the hydraulic motor 1 is switched.

Reference numeral 6 denotes a brake valve provided between the directional switching valve 5 and the hydraulic motor 1. The brake valve 6 has a directional switching valve 5 from the switching positions (b) and (c) to the neutral position (b). )
The inertial rotation of the hydraulic motor 1 is stopped when the hydraulic motor 1 is switched to, and includes a counter balance valve 7 (described later) provided in a valve body (not shown) and a pair of overload relief valves 10A and 10B. ing.

The valve body is provided with hydraulic source side passages 11A and 11B communicating with the hydraulic pump 2 and the tank 3, motor side passages 12A and 12B communicating with the hydraulic motor 1, a drain passage 13 and a brake release passage 14. Has been done.

Here, the counterbalance valve 7 receives the pressure oil only from the spool 8 disposed between the main pipe lines 4A and 4B and disposed in the valve body, and from the hydraulic pump 2 toward the hydraulic motor 1. The counter balance valve 7 is composed of a pair of check valves 9A and 9B that allow the fluid to flow and prevent the flow in the opposite direction. The counter balance valve 7 includes a hydraulic chamber 16 through throttles 15A and 15B.
By moving the spool 8 according to the pressure oil (pilot pressure) from the main pipelines 4A, 4B supplied to and discharged from A, 16B, the valve position is changed from the neutral position (a) to the switching position (b),
When the switch is set to (C) and the neutral position (A) is set, the drain passage 13 and the brake release passage 14 are made to communicate with each other, and when the switch positions (B) and (C) are set, the main pipeline 4 is opened.
The brake release passage 14 is communicated with A and 4B.

Then, the overload relief valve 10A,
In 10B, the counter balance valve 7 has a switching position (B),
The hydraulic motor 1 is switched from (C) to the neutral position (A).
When an excessive pressure is generated in the main pipeline 4A or 4B while the engine is rotating by inertia, this excess pressure is relieved in the main pipeline 4B or 4A on the low pressure side, and at this time, it flows through the overload relief valves 10A and 10B. The resistance force of the pressure oil absorbs the inertia energy of the hydraulic motor 1 that rotates inertially, and gradually applies a braking force to the hydraulic motor 1.

Further, the drain passage 13 leaks from the hydraulic motor 1 among the pressure oil supplied to the hydraulic motor 1.
A part of the pressure oil is discharged as drain to the tank 3. Further, the drain passage 13 is also connected to an oil chamber 17B of a brake device 17 which will be described later, and the brake release pressure supplied into the oil chamber 17B is compensated for being discharged to the tank 3 when the hydraulic motor 1 is stopped. It is supposed to do.

Further, in the brake release passage 14, when the counterbalance valve 7 is in the switching positions (b) and (c), the pressure oil on the high pressure side out of the pressure oil flowing through the main pipelines 4A, 4B is braked by the braking device 17. Is supplied to the oil chamber 17B as a brake release pressure, and when the counterbalance valve 7 is at the neutral position (a), the pressure oil in the oil chamber 17B is discharged to the tank 3 through the drain passage 13.

Reference numeral 17 denotes a negative type brake device attached to the hydraulic motor 1 called a parking brake. The brake device 17 includes a braking spring 17A, an oil chamber 17B and the like, and the braking spring 17A normally controls the hydraulic motor 1. It gives power. Then, the brake device 17 operates from the brake release passage 14 to the oil chamber 17 when the hydraulic motor 1 is driven.
When the pressure oil is supplied to B, the braking spring 17A is compressed and deformed by the pressure of the pressure oil at this time, and the braking on the hydraulic motor 1 is released.

In the traveling hydraulic circuit of the hydraulic excavator configured as described above, first, when the direction switching valve 5 is in the neutral position (a), the braking device 17 applies the braking force to the hydraulic motor 1 by the braking spring 17A. , Prevent the vehicle from moving carelessly.

Next, when the operator switches the direction switching valve 5 from the neutral position (a) to, for example, the switching position (b) to drive the vehicle, the pressure oil discharged from the hydraulic pump 2 is transferred to the direction switching valve 5 and The return oil from the hydraulic motor 1 is supplied as a motor drive pressure from the main pipeline 4A to the hydraulic motor 1 via the counter balance valve 7, and the return oil from the hydraulic motor 1 passes from the main pipeline 4B to the tank 3 via the counter balance valve 7 and the direction switching valve 5. Return to. As a result, the hydraulic motor 1 rotates to drive the vehicle.

On the other hand, when the direction switching valve 5 is switched from the neutral position (a) to the switching position (b), the hydraulic pump 2
The pressure oil discharged from is supplied as pilot pressure to the hydraulic chamber 16A via the throttle 15A, and the counterbalance valve 7 is switched from the neutral position (a) shown in FIG. 5 to the switching position (b). As a result, the pressure oil (motor drive pressure) from the main pipeline 4A is supplied to the hydraulic pressure source side passage 11A and the brake release passage 14
Is supplied into the oil chamber 17B of the brake device 17 via
The brake device 17 compresses and deforms the braking spring 17A by the brake release pressure at this time to release the braking of the hydraulic motor 1.

Next, when the directional control valve 5 is returned to the neutral position (a) in order to stop the rotation of the hydraulic motor 1, the differential pressure between the main pipelines 4A and 4B becomes small, so the counter balance valve 7 Is switched to the neutral position (a), the brake release passage 14 communicates with the drain passage 13, and the hydraulic pressure source side passages 11A, 11B and the motor side passages 12A, 12B are cut off.

As a result, the pressure oil is confined in the main pipelines 4A, 4B between the hydraulic motor 1 and the counterbalance valve 7, and when the hydraulic motor 1 inertially rotates due to an inertial load from the vehicle at this time, The hydraulic motor 1 acts as a pump, and discharges the pressure oil sucked from the main pipeline 4A side to the main pipeline 4B side.

At this time, when the pressure in the main pipe line 4B reaches the relief pressure of the overload relief valve 10B constituting the brake valve 6, the overload relief valve 10B opens to supply pressure oil to the main pipe line 4A side. Relief is performed, and at this time, the inertial energy of the hydraulic motor 1 is absorbed by the resistance force of the pressure oil flowing through the overload relief valve 10B, and the hydraulic motor 1 is gradually stopped.

When the directional control valve 5 is switched to the neutral position (a) as described above, the brake release passage 14 communicates with the tank 3 via the drain passage 13. As a result, the pressure oil in the oil chamber 17B of the brake device 17 is transferred to the braking spring 17
It is discharged to the tank 3 through the brake release passage 14 and the drain passage 13 by the urging force of A, and the brake device 17
Serves as a parking brake to brake the hydraulic motor 1.

[0020]

By the way, as described above, the operator operates the directional control valve 5 in order to drive and stop the vehicle. For example, the directional control valve 5 is moved to the neutral position (a).
When the hydraulic motor 1 is suddenly switched to the switching position (B) and the hydraulic motor 1 is started, the pressure oil flowing through the main pipeline 4A is braked from the hydraulic pressure source side port 11A of the counterbalance valve 7 via the brake release passage 14. It flows toward the oil chamber 17B of the device 17 with a relatively large flow rate. Therefore, there is a problem that the brake device 17 is suddenly operated by the pressure oil introduced into the oil chamber 17B to generate the drain surge pressure in the drain passage 13, thereby damaging the hydraulic motor 1.

Further, from the state in which the directional control valve 5 is switched to the switching position (b) or (c) to drive the hydraulic motor 1, the directional control valve 5 is switched to the neutral position (a) to drive the hydraulic motor 1. When stopped, the oil chamber 1 of the brake device 17
Since the oil liquid in 7B is rapidly discharged to the drain passage 13 via the brake release passage 14 by the urging force of the braking spring 17A, the brake device 17 should suddenly apply the braking force to the hydraulic motor 1. become. On the other hand, since the hydraulic motor 1 continues to rotate due to inertia during the transition from the drive state to the stop state, it is driven by the hydraulic motor 1 by applying a sudden braking force to the hydraulic motor 1. There is a problem that a large braking shock is generated in the load and the hydraulic motor 1 is stopped while dragging the brake device 17, so that the brake device 17 is worn or damaged early.

The present invention has been made in view of the above-mentioned problems of the prior art, and the damage of the brake device due to the generation of drain surge pressure at the time of starting the hydraulic motor and the sudden application of the braking force when the hydraulic motor is stopped. A hydraulic motor with a brake device that can prevent the above-mentioned problems, delay the braking release timing of the brake device at low temperatures, and further reduce the manufacturing cost by simplifying the configuration. The purpose is to do.

[0023]

In order to solve the above-mentioned problems, the present invention relates to a casing, an output shaft rotatably supported in the casing, a valve body attached to the casing, and A rotor in which a plurality of cylinders are provided in the casing so as to be rotatable integrally with the output shaft and in the axial direction, a plurality of pistons slidably fitted in the cylinders of the rotor, and an end surface of the rotor A switching valve plate provided between the valve body and the valve body and having a pair of switching ports that intermittently communicate with each cylinder of the rotor; and a switching valve plate provided in the casing for supplying pressure oil to the oil chamber. The present invention is applied to a hydraulic motor having a braking device including a negative type braking device that releases braking on the output shaft.

The feature of the configuration adopted by the invention of claim 1 is that the valve body has a counterbalance valve consisting of a spool and a pair of check valves which are displaced in accordance with the pressure supplied from a hydraulic pressure source. A brake valve having a pair of overload relief valves is provided, and the valve body has a hydraulic pressure source side passage connected to a hydraulic pressure source with the spool of the counterbalance valve interposed therebetween, and the rotor via the switching valve plate. A motor-side passage that communicates with each cylinder, and a brake release passage that selectively communicates the oil chamber of the brake device with the hydraulic pressure source-side passage and the drain passage with the spool of the counterbalance valve interposed therebetween, In addition, a throttle is provided in the valve body in the middle of the brake release passage.

Further, the invention of claim 2 is that the throttle is a small hole which is located in the vicinity of the hydraulic pressure source side passage and is directly provided in the valve body.

Further, in the invention of claim 3, the spool of the counterbalance valve is arranged in a spool sliding hole formed so as to traverse the valve body, and the hydraulic pressure source side passage is substantially aligned with the spool sliding hole. They are arranged as a pair of oil passages positioned in the orthogonal direction, one end of which is opened to the spool sliding hole and the other end is opened to the peripheral surface side of the valve body, and the brake release passage is located on the hydraulic pressure source side. It is located between the passages and is disposed in a direction substantially orthogonal to the spool sliding hole, and one end of the spool sliding hole is opened to the spool sliding hole, and the other end is opened to the abutting end face with the casing. It is provided as a throttle small hole in the middle of the brake release passage near the passage on the hydraulic power source side.

Furthermore, in the invention of claim 4, a casing-side brake release passage is provided in the casing, one end of the casing-side brake release passage is opened to the oil chamber of the brake device, and the other end is opened by the valve. The opening is made at the end face that abuts against the body so as to communicate with the brake release passage on the valve body side.

[0028]

According to the structure of claim 1, when the hydraulic motor is started, when the pressure oil is supplied into the oil chamber of the brake device to release the braking on the output shaft, the flow rate of the pressure oil is released from the brake. Since it is controlled by the throttle provided in the middle of the passage, the braking of the brake device with respect to the hydraulic motor can be released gently. Therefore, generation of drain surge pressure can be suppressed and damage to the hydraulic motor and the like can be prevented.

Further, when the hydraulic motor is stopped, when the oil liquid in the oil chamber of the brake device is discharged to the outside via the brake release passage, the oil liquid discharged by the throttle provided in the middle of the brake release passage. By controlling the flow rate of, the braking of the hydraulic motor can be performed gently. Therefore, it is possible to prevent a large braking shock from occurring in the load driven by the hydraulic motor, and it is possible to prevent early wear or damage due to the brake device being dragged by the hydraulic motor. .

According to the second aspect of the present invention, the throttle is located in the vicinity of the hydraulic pressure source side passage and is a small hole provided directly in the valve body, so that the hydraulic pressure source is supplied to and discharged from the hydraulic pressure source side passage. The temperature of the pressure oil warms the area around the small hole,
It is possible to prevent the viscosity of the pressure oil flowing through the throttle from increasing at low temperatures, and to prevent the braking and releasing of the braking of the hydraulic motor by the brake device from being delayed at low temperatures.

Further, according to the third aspect of the present invention, the throttle can be simplified by using the throttle small hole provided in the middle of the brake release passage.

Further, according to the structure of claim 4, by mounting the valve body in the casing, the casing-side brake release passage provided in the casing and the valve body-side brake release passage provided in the valve body communicate with each other. Therefore, the brake release passage having the throttle in the middle of the passage can be easily formed.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In the embodiment, the same components as those of the conventional technique shown in FIG. 5 described above are designated by the same reference numerals, and the description thereof will be omitted.

In the figure, reference numeral 21 denotes a casing of a hydraulic motor having a brake device according to this embodiment. The casing 21 is formed in a stepped tubular shape as a whole, and has a small diameter portion 21A on the front side and a large diameter portion 21B on the rear side. Has become.
Further, a shaft insertion hole 21C is formed on the inner peripheral side of the small diameter portion 21A, and a large diameter hole 21D is formed on the inner peripheral side of the large diameter portion 21B. The opening end side of the large diameter portion 21B will be described later. It is an abutting end surface 21E with which the valve body 22 abuts.

Reference numeral 22 is a valve body mounted so as to close the rear side of the casing 21.
A brake valve 39, which will be described later, and hydraulic pressure source side passages 49A, 49
B, motor side passages 50A and 50B, a drain passage 51, a brake release passage 52, and the like are formed. The valve body 22 is attached with its abutting end surface 22A abutting against the abutting end surface 21E of the casing 21 to cover the large-diameter hole 21D of the casing 21, so that the large-diameter hole 21D of the casing 21 is inserted. A rotor accommodating portion 23 closed by the valve body 22 is formed.

Reference numeral 24 denotes a rotor accommodating portion 23 of the casing 21.
An output shaft rotatably disposed within the output shaft 24,
The front side is rotatably supported by the shaft insertion hole 21C of the casing 21 via the front side bearing 25, and the rear side is rotatably supported by the valve body 22 via the rear side bearing 26.

27 is a rotor housing portion 23 of the casing 21.
2 shows a rotor that is positioned inside and is spline-coupled to the output shaft 24 and is provided so as to be rotatable integrally with the output shaft 24. A plurality of cylinders 28 extending axially around the output shaft 24 in the rotor 27, 28, ... are drilled at equal intervals,
Pistons 29, 29, ... Are slidably fitted in the respective cylinders 28.

A switching valve plate 30 is fixed to the valve body 22 and is located between the rear end surface of the rotor 27. The switching valve plate 30 is a cylinder port 28A provided in each cylinder 28 of the rotor 27. It has a pair of switching ports 30A, 30A which communicates intermittently with.

.. indicate a plurality of shoes swingably provided on the protruding end side of each piston 29, and the tip end side of each shoe 31 is always slid on a smooth surface 32A of a swash plate 32 described later. Touching.

Reference numeral 32 denotes a disc-shaped swash plate located in the rotor accommodating portion 23 and provided on the front side of the casing 21.
In the swash plate 32, a smooth surface 32A with which the shoes 31 are in sliding contact is inclined with respect to the axis of the output shaft 24, and a shaft insertion hole 32B through which the output shaft 24 is inserted is formed in the center thereof. .
As a result, the stroke of each piston 29 provided with the shoe 31 that slides on the smooth surface 32A is adjusted, and the rotor 2
7, the flow rate of the pressure oil supplied and discharged from each cylinder 28 of No. 7 can be adjusted appropriately.

Reference numeral 33 denotes a brake device provided in the large diameter portion 21B of the casing 21, and the brake device 33
Are a plurality of brake plates 34, 34, ... Spline-coupled to the inner peripheral side of the large-diameter portion 21B, and a plurality of friction plates 35, 35 are spline-coupled to the outer peripheral side of the rotor 27 and face each brake plate 34. ,, and a cylindrical brake piston 36 slidably fitted to the inner peripheral side of the large-diameter portion 21B so that the brake plates 34 and the friction plates 35 are brought into sliding contact with each other.
An annular braking spring 37, which is provided between the brake piston 36 and the valve body 22 and constantly biases the brake piston 36 in a direction (braking side) for pressing the brake plates 34 and the friction plates 35, and a brake. The brake piston 36 is displaced toward the brake release side by being formed between the piston 36 and the inner peripheral surface of the large-diameter portion 21B of the casing 21 and introducing pressure oil (brake release pressure) from a brake release passage 52 described later. The oil chamber 38 has a ring shape.

Reference numeral 39 denotes a brake valve provided in the valve body 22 according to the present embodiment. The brake valve 39 includes a counter balance valve 40 composed of a pair of check valves 9A and 9B and a spool 41 described later, and a pair of counter balance valves 40. It is composed of overload relief valves 10A and 10B.

Reference numeral 41 designates a spool which constitutes the counterbalance valve 40 together with the pair of check valves 9A and 9B. The spool 41 has a spool sliding hole 42 formed across the valve body 22, as shown in FIG. It is slidably inserted in. Here, in the spool sliding hole 42, a hydraulic pressure source side oil groove 43 communicating with the hydraulic pressure source side passages 49A and 49B is provided.
A, 43B, motor-side oil grooves 44A, 44B communicating with the motor-side passages 50A, 50B, a drain oil groove 45 communicating with the drain passage 51, and a brake release oil groove 46 communicating with the brake release passage 52 are opened. are doing.

The counterbalance valve 40 moves the spool 41 in accordance with the pressure oil (pilot pressure) supplied to and discharged from the hydraulic chambers 48A and 48B via the throttles 47A and 47B, so that the valve position is in the neutral position. Switching from (a) to the switching positions (b) and (c), for example, when in the neutral position (a), the drain oil groove 45 and the brake release oil groove 46 are made to communicate with each other, and the oil chamber 38 of the brake device 33 is closed. The pressure oil is returned into the tank 3 through the brake release passage 52 and the drain passage 51.

When the pressure oil is introduced into the hydraulic chamber 48A and the spool 41 is switched to the switching position (B), the pressure oil from the hydraulic pressure source side passage 49A is transferred from the brake releasing oil groove 46 to the brake releasing passage. Brake device 3 via 52
3 is introduced into the oil chamber 38 and pressure oil is introduced into the hydraulic chamber 48B to be switched to the switching position (C), the pressure oil from the hydraulic pressure source side passage 49B is released from the brake release oil groove 46. Oil chamber 3 of brake device 33 via passage 52
It is supposed to be introduced in 8.

49A and 49B are hydraulic source side passages formed in the valve body 22 and connected to the hydraulic pump 2 as a hydraulic source and the tank 3 via the main pipelines 4A and 4B,
As shown in FIG. 2, the hydraulic pressure source side passages 49A and 49B are formed as a pair of oil passages positioned in a direction substantially orthogonal to the spool sliding hole 42. One end of each of the hydraulic pressure source side passages 49A and 49B communicates with the hydraulic pressure source side oil grooves 43A and 43B, and the other end of each of the hydraulic pressure source side passages 49A and 49B opens to the circumferential surface side of the valve body, such as a joint (not shown). The main pipelines 4A and 4B are connected via the.

50A and 50B are formed in the valve body 22, and a hydraulic pressure source side passage 49 is provided via a counter balance valve 40.
Motor-side passages connected to A and 49B, one end of each of the motor-side passages 50A and 50B communicates with the motor-side oil grooves 44A and 44B, and the other end thereof connects to each switching port 30A of the switching valve plate 30. It is adapted to communicate with each cylinder 28 of the rotor 27 via.

Reference numeral 51 denotes a drain passage formed in the valve body 22. The drain passage 51 opens into the rotor accommodating portion 23 of the casing 21 and a part of the pressure oil leaking from each cylinder 28 of the rotor 27. Is discharged to the tank 3. Further, the drain passage 51 is provided in the drain oil groove 4
5, the brake release pressure supplied into the oil chamber 38 of the brake device 33 is compensated for being discharged to the tank 3 when the hydraulic motor 1 is stopped.

Reference numeral 52 denotes a brake release passage according to this embodiment provided between the hydraulic pressure source side passages 49A and 49B. The brake release passage 52 is, as shown in FIGS. 1 and 3,
It comprises a casing side brake release passage 53 provided in the casing 21 and a valve body side brake release passage 54 provided in the valve body 22. Here, one end of the casing side brake release passage 53 is opened to the oil chamber 38 of the brake device 33, and the other end side is opened to the abutting end face 21E of the casing 21.

On the other hand, the valve body side brake release passage 54
Is formed in a direction substantially orthogonal to the spool sliding hole 42, and one end side communicates with a bifurcated brake release oil groove 46 that opens in the spool sliding hole 42 with the drain oil groove 45 sandwiched between the one end side and the other end side. A first passage portion 54A whose side is closed by a sealing plug, and a hole formed in a direction orthogonal to the first passage portion 54A, one end side being opened to the first passage portion 54A and the other end side being closed by the sealing plug. The second passage portion 54B and the first
A third passage portion 54C which is bored in parallel with the passage portion 54A, one end side of which communicates with the second passage portion 54B through a throttle small hole 55 described later, and the other end side of which opens to the abutting end surface 22A of the valve body 22. It consists of

By attaching the valve body 22 to the casing 21, the abutting end face 21E of the casing 21 is
The brake release passage 53 formed on the casing side and the third passage portion 54C of the brake release passage 54 on the valve body side opened on the abutting end surface 22A of the valve body 22 are connected in a liquid-tight manner to form the brake release passage 52. It is supposed to be done.

Reference numeral 55 denotes a throttle small hole provided between the second passage portion 54B and the third passage portion 54C of the valve body side brake release passage 54, and the throttle small hole 55 is the valve body side brake release passage. The diameter of the pressure oil is sufficiently smaller than that of 54, and the flow rate of the pressure oil flowing between the second passage portion 54B and the third passage portion 54C is controlled as described later. Then, the throttle small hole 55 is formed in the second passage portion 54B and the third passage portion 5
4C, for example, the valve body 22
It is considered that the throttle small hole 55 can be easily drilled from the outside of the valve body 22 by using a drill having a diameter smaller than that of the third passage portion 54C before the third passage portion 54C is drilled. .

The hydraulic motor having the brake device according to the present embodiment has the above-mentioned structure, and its basic operation is not different from that of the prior art.

However, in the present embodiment, the throttle small hole 55 is provided in the middle of the brake release passage 52 that guides the pressure oil discharged from the hydraulic pump 2 into the oil chamber 38 of the brake device 33. Since the configuration is such that the flow rate of the pressure oil introduced into the is controlled, the following operational effects can be obtained.

First, when the direction switching valve 5 is switched from the neutral position (a) to the switching position (b) or (c) at the time of starting the hydraulic motor, the counter balance valve 40 works in conjunction with the direction switching valve 5. The neutral position (a) is switched to the switching positions (b) and (c). As a result, pressure oil (brake release pressure) is introduced into the oil chamber 38 of the brake device 33 from the high pressure side of the hydraulic pressure source side passages 49A and 49B through the brake release passage 52, and the brake device 33 brakes at this time. The release pressure compresses and deforms the braking spring 37 to release the braking state of the hydraulic motor.

At this time, since the throttle small hole 55 for controlling the flow rate of the pressure oil is provided in the middle of the brake release passage 52, the pressure oil introduced into the oil chamber 38 is given a throttle action. By gradually supplying the pressure oil to the oil chamber 38 of the brake device 33, the braking of the hydraulic motor can be gradually released. As a result, it is possible to suppress the occurrence of drain surge pressure in the drain passage 51 due to the rapid supply of pressure oil into the oil chamber 38 of the brake device 33, and the hydraulic motor is damaged by the drain surge pressure. Can be effectively prevented.

Next, when the hydraulic motor in the operating state is stopped, when the direction switching valve 5 is switched from the switching position (b) or (c) to the neutral position (a), the counter balance valve 40 is moved to the neutral position. Switched to (a). As a result, the drain oil groove 45 and the brake release oil groove 46 communicate with each other, and the pressure oil in the oil chamber 38 of the brake device 33 is discharged to the drain passage 51 via the brake release passage 52.
When the brake piston 36 is pressed by the braking spring 37 and displaced toward the braking side, the brake plates 34 and the friction plates 35 are brought into sliding contact with each other to apply a braking force to the output shaft 24, and the hydraulic motor stops. Like

At this time, the flow rate of the pressure oil discharged from the oil chamber 38 to the drain passage 51 via the brake release passage 52 is controlled by the throttle hole 55 provided in the middle of the brake release passage 52. The piston 36 is gradually displaced toward the braking side. Therefore, by gradually sliding the brake plates 34 and the friction plates 35 into contact with each other,
The braking force can be gradually applied to the hydraulic motor. As a result, it is possible to prevent a large braking shock from being generated in the load driven by the hydraulic motor, and the braking device 3
It is possible to effectively prevent early wear or damage of the brake device 33 due to the hydraulic motor stopping while dragging 3.

Further, as described above, the brake release passage 52
Since the throttling small hole 55 for controlling the flow rate of the pressure oil flowing therein is provided directly on the valve body 22 located between the hydraulic pressure source side passages 49A and 49B, it is discharged from the hydraulic pump 2 or returned from the rotor 27. The pressure oil is the hydraulic pressure source side passage 49A, 49.
By circulating B, it is possible to prevent the viscosity of the pressure oil flowing through the throttle small hole 55 from increasing, for example, by warming the periphery of the throttle small hole 55 with heated hydraulic oil.
Therefore, the flow rate of the pressure oil introduced into the oil chamber 38 of the brake device 33 through the small throttle hole 55 is regulated more than necessary, which delays the release of braking of the hydraulic motor and the small throttle. By restricting the flow rate of the pressure oil discharged from the oil chamber 38 through the hole 55 more than necessary, it is possible to eliminate the situation where the braking of the hydraulic motor is delayed, and the braking operation of the hydraulic motor and The braking release operation can be performed stably.

Moreover, the throttle small hole 55 is located in the middle of the valve body side brake release passage 54 forming the brake release passage 52, and the second passage portion 54B and the second passage portion 54B forming the valve body side brake release passage 54. Since the structure is provided between the valve body 22 and the third passage portion 54C, for example, before the third passage portion 54C is bored in the valve body 22, a drill having a smaller diameter than the third passage portion 54C is used to remove the valve body 22 from the valve body 22. The throttle small hole 55 can be easily formed from the outside. Therefore, the structure of the brake release passage 52 having the small throttle hole 55 can be simplified, and the manufacturing cost can be reduced.

In the above embodiment, the throttle small hole 55 is provided between the second passage portion 54B and the third passage portion 54C forming the valve body side brake release passage 54 as an example. The present invention is not limited to this, for example, it may be provided between the brake release oil groove 46 and the first passage portion 54A, or between the first passage portion 54A and the second passage portion 54B. It may be configured.

Further, in the above-mentioned embodiment, the swash plate type hydraulic motor using the swash plate 32 is exemplified, but it may be applied to, for example, a swash shaft type hydraulic motor or a radial piston type hydraulic motor. .

[0063]

As described above in detail, according to the first aspect of the invention, the throttle for controlling the flow rate of the pressure oil is provided in the middle of the brake release passage for guiding the pressure oil into the oil chamber of the brake device. Therefore, for example, when the hydraulic motor is started, pressure oil is gradually introduced into the oil chamber by the throttling action of the throttle,
The braking of the hydraulic motor can be gradually released. As a result, generation of drain surge pressure can be reliably suppressed, and damage to the hydraulic motor due to the drain surge pressure can be effectively prevented. Further, for example, when the hydraulic motor is stopped, the flow rate of the pressure oil discharged from the oil chamber through the brake release passage is controlled, and the brake device is gradually displaced toward the braking side. Can be given. As a result, it is possible to prevent a large braking shock from being generated in the load driven by the hydraulic motor, and it is possible to prevent the braking device from being worn or damaged early by stopping the hydraulic motor while dragging the braking device. Can be prevented.

According to the second aspect of the present invention, the throttle is formed as a small hole located in the vicinity of the hydraulic pressure source side passage and directly provided in the valve body, so that the hydraulic pressure source is supplied to the hydraulic pressure source side passage. Since the periphery of the small hole is warmed by the temperature of the pressure oil to be generated, it is possible to prevent the viscosity of the pressure oil flowing through the throttle from increasing at a low temperature. As a result, the flow rate of the pressure oil introduced into the oil chamber of the brake device through the small hole is regulated more than necessary, which delays the release of braking of the hydraulic motor, and the oil flow through the small hole. By controlling the flow rate of the pressure oil discharged from the chamber more than necessary, it is possible to eliminate the situation where the braking of the hydraulic motor is delayed, and to stabilize the braking and releasing operations of the hydraulic motor. It can be carried out.

Further, according to the invention of claim 3, the throttle for controlling the flow rate of the pressure oil flowing through the brake release passage is provided with:
Since it is configured as a throttle small hole provided in the middle of the brake release passage, the structure of the throttle can be simplified.

Further, according to the structure of claim 4, by mounting the valve body in the casing, the casing-side brake release passage provided in the casing and the valve-body-side brake release passage provided in the valve body communicate with each other. With this configuration, it is possible to easily form a brake release passage having a throttle in the middle of the passage, which can contribute to reduction in manufacturing cost.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing a hydraulic motor having a brake device according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is an enlarged vertical sectional view showing a brake release passage and the like in FIG.

4 is a traveling hydraulic circuit diagram of a hydraulic excavator including the hydraulic motor in FIG. 1. FIG.

FIG. 5 is a traveling hydraulic circuit diagram of a hydraulic excavator including a hydraulic motor having a brake device according to a conventional technique.

[Explanation of symbols]

 10A, 10B Overload relief valve 21 Casing 22 Valve body 24 Output shaft 27 Rotor 28 Cylinder 29 Piston 30 Switching valve plate 33 Brake device 38 Oil chamber 39 Brake valve 40 Counter balance valve 41 Spool 49A, 49B Hydraulic source side passage 50A, 50B Motor side passage 51 Drain passage 52 Brake release passage 53 Casing side brake release passage 54 Valve body side brake release passage 55 Throttle small hole

Claims (4)

[Claims] 1. A casing, an output shaft rotatably supported in the casing, a valve body attached to the casing, and a plurality of members provided in the casing so as to be rotatable integrally with the output shaft. Rotor provided with a cylinder, a plurality of pistons slidably fitted in the cylinders of the rotor, and cylinders of the rotor provided between the end surface of the rotor and the valve body. A switching valve plate having a pair of switching ports that communicate intermittently, and a negative brake device that is provided in the casing and releases braking on the output shaft by supplying pressure oil to an oil chamber. In the hydraulic motor having a brake device, the valve body includes a spool and a pair of check valves that are displaced according to a pressure supplied from a hydraulic source. A brake valve having an unbalance valve and a pair of overload relief valves is provided, and the valve body has a hydraulic source side passage connected to a hydraulic source with the spool of the counter balance valve interposed therebetween, and the switching valve plate. And a brake release passage that selectively connects the oil chamber of the brake device to the hydraulic source side passage and the drain passage with the motor-side passage communicating with each cylinder of the rotor via the spool of the counter balance valve. A hydraulic motor having a brake device, characterized in that a brake is formed in the valve body in the middle of the brake release passage. 2. The throttle is a small hole located near the hydraulic pressure source side passage and provided directly in the valve body.
A hydraulic motor having the brake device described in 1. 3. A spool of the counterbalance valve is disposed in a spool sliding hole formed so as to traverse the valve body, and the hydraulic pressure source side passage is arranged in a pair substantially perpendicular to the spool sliding hole. An oil passage, one end of which is opened to the spool sliding hole and the other end of which is opened to the peripheral surface side of the valve body, and the brake release passage is located between the hydraulic pressure source side passages. The throttle valve is disposed in a direction substantially orthogonal to the spool sliding hole, one end of which is opened to the spool sliding hole, and the other end of which is opened to an abutting end face with the casing. The hydraulic motor having the brake device according to claim 1, wherein the hydraulic motor is provided as a throttle small hole near the brake release passage in the vicinity thereof. 4. A casing-side brake release passage is provided in the casing, one end of the casing-side brake release passage is opened to an oil chamber of the brake device, and the other end is opened to an abutting end face with the valve body. The hydraulic motor having the brake device according to claim 3, configured to communicate with the brake release passage on the valve body side.