JP2000220560A - Hydraulic motor with braking device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the durability of sealing members etc., by preventing the radical pressure rising in a drain chamber in the start of a hydraulic motor. SOLUTION: A supply side throttle section 22 is provided in the middle of a supply passage 17 to supply pressure oil to a hydraulic chamber 12 to displace a brake piston 11 to the brake releasing side. Through this constitution, when a hydraulic motor is started, the flow quantity of the pressure oil flowing into the hydraulic chamber 12 passing through the supply passage 17 is restricted by the supply side restricting section 22. Therefore, this constitution can prevent the brake piston 11 from the instant displacement due to the flowing of a great quantity of pressure oil into the hydraulic chamber 12 at a stroke. Therefore, even when a hydraulic motor is suddenly started, the pressure in a drain chamber 4 is prevented from suddenly rising. The durability of sealing members such as O-rings 3 can thus be improved.

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 suitable for use as, for example, a hydraulic motor for running a hydraulic excavator, a hydraulic motor for turning or a hydraulic motor for a rope winch.

[0002]

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

Here, a hydraulic motor having a negative type brake device is provided with a casing, an output shaft rotatably supported by the casing, and a pressure oil provided inside the casing and supplied with pressure oil from outside. A rotor for driving the output shaft is provided, and a negative brake device for applying a brake to the rotor when the rotor stops rotating.

Here, the negative type brake device is
An annular fixed brake plate provided on the casing side, a movable brake plate provided on the rotor side so as to overlap the fixed brake plate, and an axially displaceably provided on an inner peripheral surface side of the casing. And a brake piston that releases frictional engagement between the fixed brake plate and the movable brake plate by supplying pressure oil to a hydraulic chamber defined between the casing and the brake piston. A spring that constantly urges the brake piston in a direction in which the fixed brake plate and the movable brake plate frictionally engage with each other, and a supply passage provided in the casing for supplying pressure oil to the hydraulic chamber. And a discharge passage provided in the brake piston for discharging the pressure oil in the hydraulic chamber to the drain chamber side in the casing (example). If, Japanese Utility Model 57-44233, JP-Utility Model 58-96102 Patent Publication).

[0005] The above-mentioned discharge passage discharges the pressure oil in the hydraulic chamber to the drain chamber side in the casing.
When the hydraulic motor is stopped, the pressure oil in the hydraulic chamber is discharged through the discharge passage, and the pressure in the hydraulic chamber is reduced. Therefore, the brake piston is pressed against the brake plate by the biasing force of the spring, and the rotor is braked. Further, the discharge passage is a throttle passage having a small passage area for restricting a discharge flow rate of the oil liquid from the hydraulic chamber to the drain chamber side of the casing so that a pressure rises in the hydraulic chamber when pressure oil is supplied to the hydraulic chamber. It is formed as.

When the hydraulic motor thus configured is started, the pressure oil from the hydraulic pump flows into the hydraulic chamber through the supply passage. At this time, part of the pressure oil is discharged from the discharge passage to the drain chamber side in the casing. However, since the discharge passage is formed as a small-diameter throttle passage, the discharge amount of the pressure oil is small due to flow resistance and the like. Is limited to As a result, the pressure in the hydraulic chamber rises due to the pressure oil supplied from the hydraulic pump, and this pressure displaces the brake piston in a direction to release the frictional engagement between the fixed brake plate and the movable brake plate, and gives the pressure to the rotor. Release the braking that was applied.

Further, when the hydraulic motor is stopped, the supply of the pressure oil from the hydraulic pump is cut off, and the pressure oil in the hydraulic chamber is only discharged from the discharge passage to the drain chamber side. As a result, the pressure in the pressure chamber decreases, so that the brake piston is pressed against the brake plate by the spring, and braking is applied to the rotor.

[0008]

In the above-mentioned prior art, the flow rate of the pressure oil discharged from the hydraulic chamber to the drain chamber side of the casing is controlled by the discharge passage formed as a throttle passage having a small passage area. Limited. On the other hand, the flow rate of the pressure oil supplied to the hydraulic chamber is not particularly limited. For this reason, when the hydraulic motor is started, a very large pressure substantially equal to the pressure (hydraulic pressure) for driving the rotor to rotate acts on the hydraulic chamber, and the brake piston instantaneously acts against the spring to release the brake. Move to

When the brake piston instantaneously moves to the braking release side, the internal volume corresponding to the amount of movement of the brake piston changes instantaneously in the drain chamber, so that the pressure in the drain chamber rapidly increases. In addition, there is a possibility that the seal member and the like may be damaged, and there is a problem that durability is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to prevent a sudden increase in pressure in a drain chamber at the time of startup and to improve durability of a seal member and the like. An object of the present invention is to provide a hydraulic motor having a brake device that can be used.

[0011]

SUMMARY OF THE INVENTION A hydraulic motor having a brake device according to the present invention is provided with a casing, an output shaft rotatably supported by the casing, and a pressure oil which is provided in the casing and which is supplied with pressure oil from outside. A rotor that drives the output shaft to rotate, and a negative-type brake device that applies braking to the rotor when the rotor stops rotating.The brake device is provided on the casing side. An annular fixed brake plate, a movable brake plate provided on the rotor side so as to overlap the fixed brake plate, and an axially displaceable provided on an inner peripheral surface side of the casing. A brake piston that releases frictional engagement between the fixed brake plate and the movable brake plate by supplying pressure oil to a hydraulic chamber defined in the case; A spring that is always provided between the fixed brake plate and the movable brake plate in a direction in which the fixed brake plate and the movable brake plate frictionally engage with each other. It is constituted by a supply passage provided in the casing and a discharge passage provided in the brake piston for discharging the pressure oil in the hydraulic chamber to the drain chamber side in the casing.

Then, in order to solve the above-mentioned problem,
A feature of the structure adopted in the first aspect of the invention is that a supply-side throttle portion that restricts a flow rate of the pressure oil flowing into the hydraulic chamber is provided in the supply passage, and the discharge passage is discharged from the hydraulic chamber to the drain chamber side. The present invention has a configuration in which a discharge-side throttle portion for restricting the flow rate of the pressure oil is provided.

With this configuration, when the hydraulic oil is supplied to the hydraulic chamber via the supply passage when the hydraulic motor is started, the brake piston is displaced to the braking release side by the pressure in the hydraulic chamber, so that the braking is released. can do.
At this time, since the supply-side throttle provided in the supply passage limits the flow rate of the pressure oil, it is possible to prevent a sudden displacement of the brake piston and suppress a rise in pressure in the drain chamber. On the other hand, when the hydraulic motor is stopped, the supply of pressure oil to the hydraulic chamber is cut off, and the pressure oil in the hydraulic chamber is discharged to the drain chamber side through the discharge passage, so that the spring moves the brake piston to the braking side. And braking is provided.

According to the second aspect of the present invention, the supply-side throttle portion is set so that the flow rate of the pressure oil is larger than the flow rate of the pressure oil by the discharge-side throttle portion.

With this configuration, when the hydraulic motor is started, the supply passage and the supply-side throttle are smaller than the flow rate of the pressure oil discharged from the hydraulic chamber to the drain chamber through the discharge passage and the discharge-side throttle portion. Since the flow rate of the pressure oil supplied to the hydraulic chamber via the portion becomes larger, the brake piston can be displaced to the brake release side by the pressure oil supplied to the hydraulic chamber.

According to the third aspect of the present invention, the supply-side restricting portion,
The discharge side throttle portion is formed as a thin blade orifice.

With this configuration, the influence of the temperature change (viscosity change) of the pressure oil passing through the throttle can be substantially eliminated, and the pressure oil can be stably circulated in the supply passage and the discharge passage. .

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a hydraulic motor having a brake device according to an embodiment of the present invention will be described in detail with reference to FIGS.

Reference numeral 1 denotes a casing of a hydraulic motor. The casing 1 is formed in a stepped bottomed cylindrical shape whose front side (right side in the figure) is closed, and its inner peripheral side is from the front side to the rear side (see FIG. The hole is a stepped hole that expands toward a small-diameter hole 1A, a medium-diameter hole 1B, and a large-diameter hole 1C toward the middle left side. Also, on the inner peripheral side of the casing 1, a plurality of engaging projections 1D, 1 with which a fixed brake plate 9 described later engages near the front side of the middle diameter hole 1B.
D (only two shown) extend in the axial direction.

Reference numeral 2 denotes a valve body mounted on the casing 1 so as to close the rear side thereof. The valve body 2 forms a lid of the casing 1 and has a large-diameter and short cylindrical portion 2A on its front side. Have. Here, the cylindrical portion 2A is inserted into the large-diameter hole 1C of the casing 1 in a liquid-tight manner via the O-ring 3, and its end surface is in contact with a stopper surface 2B with which a rear-side end surface 11D of the brake piston 11 described later comes into contact. Has become. The stopper surface 2B closes a large-diameter passage 24 of a discharge passage 23 to be described later by contacting the rear end surface 11D of the brake piston 11, thereby minimizing the outflow of pressure oil from the hydraulic chamber 12. is there.

Reference numeral 4 denotes a drain chamber defined by the casing 1 and the valve body 2, and the drain chamber 4 stores an oil liquid leaked from between a rotor 6 and a switching valve plate 7, which will be described later. It is almost at atmospheric pressure. Then, the oil liquid in the drain chamber 4 is returned to an oil tank (neither is shown) via a drain pipe or the like.

Reference numeral 5 denotes an output shaft extending in the center of the casing 1 in the axial direction. The output shaft 5 is rotatably supported between the front side of the casing 1 and the valve body 2. The output shaft 5 is connected to an input side of a planetary gear reduction device (not shown) disposed, for example, on the outer peripheral side of the casing 1.

Reference numeral 6 denotes a rotor provided in the casing 1. The rotor 6 has a plurality of cylinders (not shown) extending in the axial direction at equal intervals in the circumferential direction. Splines are joined. Further, on an outer peripheral side of the rotor 6, an engagement concave groove 6 with which a movable brake plate 10 described later is engaged.
A, 6A,... Are formed at intervals in the circumferential direction.
Further, a piston is slidably inserted into each cylinder of the rotor 6, and a shoe swingably provided at a protruding end of each piston is provided with an oblique shoe provided between the rotor 6 and the casing 1. It is in sliding contact with a plate (both not shown).

Reference numeral 7 denotes a switching valve plate provided in the valve body 2 in the casing 1, and the switching valve plate 7 slidably abuts the rotor 6. The switching valve plate 7 includes
A pair of switching ports (not shown) that are intermittently connected to each cylinder of the rotor 6 are provided.

Reference numeral 8 denotes a brake device provided in the casing 1. The brake device 8 is a negative brake device that applies a brake to the rotor 6 when the rotor 6 stops rotating. The negative type brake device 8 includes a fixed brake plate 9, a movable brake plate 10, a brake piston 11, a hydraulic chamber 12, a disc spring 1
5, the supply passage 17, the discharge passage 23, and the like.

Reference numerals 9 and 9 denote a plurality of fixed brake plates provided on the inner peripheral side of the medium-diameter hole 1B of the casing 1. Each of the fixed brake plates 9 is formed as an annular plate body, and the outer peripheral side thereof is the casing 1 Engages with each of the engaging projections 1D of
The casing 1 is fixed in the circumferential direction while allowing displacement in the axial direction with respect to the casing 1.

Reference numerals 10 and 10 denote a plurality of movable brake plates provided on the outer peripheral side of the rotor 6.
Is formed as an annular plate like the fixed brake plate 9, and is arranged at a position where the outer peripheral side overlaps each fixed brake plate 9. The movable brake plate 10 has its inner peripheral side engaged with each of the engaging concave grooves 6A of the rotor 6, and is thereby fixed in the circumferential direction while allowing the rotor 6 to be displaced in the axial direction. .

Reference numeral 11 denotes a brake piston provided on the inner peripheral side of the casing 1. The brake piston 11 is formed into a stepped cylindrical shape by a small-diameter cylindrical portion 11A and a large-diameter cylindrical portion 11B. The casing 1 is fitted into the medium-diameter hole 1B, and the large-diameter cylindrical portion 11B is fitted into the large-diameter hole 1C. Also, the brake piston 11 is mounted on the front end surface 1.
1C can contact and separate from the fixed brake plate 9, and the rear end surface 11D can contact and separate from the stopper surface 2B of the valve body 2. Further, as shown in FIG. 2, the brake piston 11 is formed with a spring accommodating step 11 </ b> E in which a disc spring 15 is accommodated on the inner peripheral side of the rear end face 11 </ b> D. Notch groove 11F to allow distribution
Are formed.

The brake piston 11 is axially displaceably fitted on the inner peripheral surface side of the casing 1 and is urged in the direction of arrow A by the disc spring 15 when the hydraulic motor is stopped, so that the front end surface is 11C is in contact with the fixed brake plate 9. On the other hand, when the hydraulic motor is started,
It is displaced in the direction of arrow B by the pressure oil supplied to the hydraulic chamber 12 to release the frictional engagement between the fixed brake plate 9 and the movable brake plate 10.

Reference numeral 12 denotes an annular hydraulic chamber defined between the large-diameter hole 1C of the casing 1 and the brake piston 11. The hydraulic chamber 12 includes O-rings 13 and A liquid-tight seal 14 is provided. When hydraulic oil is supplied through the supply passage 17, the hydraulic chamber 12 displaces the brake piston 11 in the arrow B direction against the urging force of the disc spring 15, and releases the braking of the rotor 6. Is what you do.

Reference numeral 15 denotes the valve body 2 and the brake piston 11
The disc spring 15 is partially accommodated in the spring accommodating step 11E. Then, the disc spring 15 constantly urges the brake piston 11 in the direction of arrow A to frictionally engage the fixed brake plate 9 and the movable brake plate 10 via the brake piston 11,
This is to apply braking to the rotor 6.

Reference numeral 16 denotes a spool of a counterbalance valve provided on the valve body 2. The spool 16 switches between a neutral position and an operating position according to the pilot pressure. The spool 16 is connected to the hydraulic chamber 12 through a supply passage 17 described later.
It is connected to the.

Reference numeral 17 denotes a supply passage extending from the spool 16 to the hydraulic chamber 12 and supplying pressure oil to the hydraulic chamber 12. The supply passage 17 is provided in the valve body 2 and has a diameter extending from the spool 16 in the radial direction. A radial passage 18, an axial passage 19 provided in the valve body 2 and extending in the axial direction in communication with the radial passage 18, and an axial passage 19 provided in the casing 1.
A communication path 20 that connects the hydraulic pressure chamber 9 and the hydraulic chamber 12 is roughly configured. In addition, the passages 18, 19, 20
Are formed with a large passage area. further,
The connection portion between the axial passage 19 and the communication passage 20 is an O-ring 2
1 is a liquid-tight seal. When the spool 16 is switched to the operating position, a part of the pressure oil supplied from the hydraulic pump (not shown) is supplied to the supply passage 17 through the radial passage 18, the axial passage 19, and the communication passage 20. It is distributed and supplied to the hydraulic chamber 12.

Reference numeral 22 denotes a supply-side restricting portion provided in the supply passage 17. The supply-side restricting portion 22 is disposed on the upstream side of the axial passage 19, which is a connection portion with the radial passage 18, and The passage 19 has a smaller passage area than the passage 19. In addition, the supply-side restricting portion 22 forms a so-called thin-blade orifice having a short axial length, thereby reducing the influence of a temperature change.
Stable braking performance.

Here, the supply-side throttle portion 22 has a thin blade orifice shape substantially similar to the discharge-side throttle portion 25 described later.
By making the passage area larger than the passage area of the discharge-side throttle section 25, the flow rate is set to be larger than the flow rate of the pressure oil by the discharge-side throttle section 25. That is, when the hydraulic motor is started, the flow rate of the pressure oil flowing through the supply passage 17 provided with the supply-side throttle portion 22 is smaller than the flow rate of the pressure oil flowing through the discharge passage 23 provided with the discharge-side throttle portion 25. growing. Accordingly, the pressure in the hydraulic chamber can be increased by the pressure oil supplied to the hydraulic chamber 12 through the supply passage 17, and the brake piston 11 can be displaced in the direction of arrow B on the brake release side.

The supply-side throttle unit 22 is provided with a spool 16.
When the hydraulic oil is supplied to the hydraulic chamber 12 through the supply passage 17 through the supply passage 17, the flow rate of the hydraulic oil flowing into the hydraulic chamber 12 is restricted, so that the brake piston 11 is instantaneously displaced in the direction of arrow B. Has been prevented.

Reference numeral 23 denotes a discharge passage provided on the outer peripheral side of the brake piston 11. The discharge passage 23 is provided so as to penetrate the large-diameter cylindrical portion 11B of the brake piston 11 in the axial direction. And the discharge passage 23 is connected to the discharge passage 2.
The hydraulic chamber 12 and the drain chamber 4 occupy most of the length of
Large-diameter passage 24 which communicates with a large passage area between
And a discharge-side throttle portion 25 which is provided at a position facing the hydraulic chamber 12 and has a smaller passage area than the large-diameter passage 24. Further, the discharge-side throttle portion 25 is formed to have a passage area smaller than the passage area of the supply-side throttle portion 22 described above.
Further, the discharge-side throttle unit 25 is provided with the supply-side throttle unit 2 described above.
Like 2, it is formed as a thin blade orifice.

Here, the large-diameter passage 24 is open at the rear end face 11D of the brake piston 11, and the brake piston 11 is displaced in the direction of arrow B, and
When the rear end face 11D of the first valve body 1 comes into contact with the stopper face 2B of the valve body 2, it is closed by the stopper face 2B,
In this state, the amount of pressure oil discharged from the discharge passage 23 is minimized.

The discharge passage 23 is connected to the discharge-side throttle portion 2.
5 is provided at a position facing the hydraulic chamber 12 so that FIG.
As shown in the figure, even when foreign matter 26 such as chips mixed with the pressure oil flowing from the hydraulic chamber 12 to the discharge passage 23 blocks the discharge side throttle portion 25, the hydraulic motor stops and the pressure oil is stopped. When the flow stops, as shown in FIG. 4, each foreign matter 26 that has blocked the discharge-side throttle unit 25 can be dropped into the hydraulic chamber 12 by its own weight.

The hydraulic motor according to the present embodiment has the above-described configuration. Next, the operation of the hydraulic motor will be described.

First, when the hydraulic motor is driven, the direction switching valve (not shown) is switched from the neutral position to an arbitrary operating position, and the hydraulic oil from the hydraulic pump is supplied to the hydraulic motor. As a result, the pressure oil sequentially flows into each cylinder of the rotor 6 via the switching port of the switching valve plate 7, and reciprocates the piston in each cylinder. The reciprocating motion of the piston acts in the direction of rotating the rotor 6 by the swash plate, rotates the output shaft 5 integrally with the rotor 6, and drives, for example, a driving wheel connected via a reduction gear to drive the hydraulic excavator. To run.

When the hydraulic motor is started, a part of the pressure oil from the hydraulic pump flows into the hydraulic chamber 12 through the supply passage 17. Here, the supply passage 17 is provided with the supply-side restrictor 22, and the flow rate of the pressure oil is limited by the supply-side restrictor 22. Therefore, even when the hydraulic motor is suddenly started, a large amount of Can be prevented from flowing at once.

Then, the flow rate of the pressure oil by the supply-side throttle portion 22 provided in the supply passage 17 is reduced by the discharge-side throttle portion 25 provided in the discharge passage 23 for discharging the pressure oil in the hydraulic chamber 12 to the drain chamber 4 side. , The pressure inside the hydraulic chamber 12 can be increased by the pressure oil supplied through the supply passage 17.

As a result, the brake piston 11 is displaced in the direction of arrow B against the disc spring 15 by the pressure oil flowing into the hydraulic chamber 12, so that the frictional engagement between the fixed brake plate 9 and the movable brake plate 10 is achieved. Is released, and the braking of the rotor 6 is released.

On the other hand, when the hydraulic motor is stopped,
Since the supply of pressure oil to the hydraulic chamber 12 is cut off,
The internal pressure oil is only discharged from the discharge passage 23 to the drain chamber 4 side. As a result, the pressure in the hydraulic chamber 12 decreases, and the brake piston 11 is pressed against the brake plates 9 and 10 by the urging force of the disc spring 15. This allows
The brake plates 9 and 10 are frictionally engaged to apply braking to the rotor 6.

As described above, according to the present embodiment, the supply-side throttle portion 22 is provided in the supply passage 17 for supplying the hydraulic oil to the hydraulic chamber 12 to restrict the flow rate of the hydraulic oil flowing into the hydraulic chamber 12. Therefore, when the hydraulic motor is started, it is possible to prevent a large amount of pressure oil from flowing into the hydraulic chamber 12 at a stretch and the brake piston 11 from being instantaneously displaced. Thus, even if the hydraulic motor is suddenly started, the drain chamber 4
Since the internal pressure can be prevented from increasing rapidly, the durability of the sealing member such as the O-ring 3 can be increased, and the reliability of the hydraulic motor can be improved.

Further, since the flow rate of the pressure oil by the supply-side throttle section 22 is set to be greater than the flow rate of the pressure oil by the discharge-side throttle section 25, even when the hydraulic motor is started slowly,
The pressure in the hydraulic chamber 12 is increased to displace the brake piston 11, so that the braking can be reliably released and the hydraulic motor can be rotated. As a result, the brake can be prevented from being dragged, so that even when the hydraulic motor is slowly started,
It is possible to eliminate wear of the brake plates 9 and 10 and suppress generation of abnormal noise.

On the other hand, the discharge passage 23 has a large-diameter passage 24 communicating between the hydraulic chamber 12 and the drain chamber 4 with a large passage area, and a discharge-side throttle having a smaller passage area than the large-diameter passage 24. Since it is configured by the unit 25,
When the discharge passage 23 is formed, the large-diameter passage 24 can be easily drilled using a large-diameter drill, and the discharge-side throttle portion 25 having a small axial length is formed with a small-diameter drill. Can be easily drilled, improving productivity,
Manufacturing costs can be reduced.

Further, since the discharge-side throttle portion 25 is provided at a position facing the hydraulic chamber 12, the discharge passage 2
Even if foreign matter 26 such as chips mixed with the pressure oil flowing into the block 3 blocks the discharge side throttle 25, when the hydraulic motor stops and the flow of the pressure oil stops, the discharge side throttle 25 is closed. The foreign matter 26 can be dropped into the hydraulic chamber 12 by its own weight. Thereby, clogging of the discharge passage 23 can be prevented, and braking performance can be improved.

Further, since the supply-side throttle portion 22 and the discharge-side throttle portion 25 are formed as thin blade orifices, it is possible to prevent problems due to temperature change (viscosity change) of the pressure oil and stabilize the braking performance. Operability and reliability can be improved.

In the embodiment, the supply-side throttle unit 2
2. The discharge side throttle section 25 is formed as a similar thin blade orifice, and the passage area of the supply side throttle section 22 is reduced by the discharge side throttle section 25.
The flow area of the pressurized oil by the supply-side throttle section 22 is set to be larger than the flow rate of the pressurized oil by the discharge-side throttle section 25 by making the flow area larger than the passage area of the above. The present invention is not limited to this.
By making the passage area of the supply-side restrictor 22 shorter than the passage length of the discharge-side restrictor 25, the flow resistance of the supply-side restrictor 22 is reduced. May be set smaller than the discharge-side throttle unit 25, and the flow rate of the pressure oil by the supply-side throttle unit 22 may be set to be large.

In the embodiment, the supply-side throttle unit 22 is provided.
Is an axial passage 19 serving as a connection portion with the radial passage 18.
Although the case where it arrange | positioned at the upstream side was mentioned as an example, this invention is not limited to this, For example, like the 1st modification shown in FIG. A configuration may be provided on the downstream side of the axial passage 19 ′ at the connection position with the communication passage 20. As another configuration, a supply-side throttle may be provided at an intermediate position of the axial passage.

Further, as in a second modification shown in FIG. 6, the supply-side throttle portion 41 may be provided in the middle of the radial passage 18 '. As another configuration, a supply-side throttle unit may be provided in the communication path.

On the other hand, in the embodiment, the discharge side throttle unit 25
Is described as being provided at a position facing the hydraulic chamber 12, but the present invention is not limited to this. For example, as shown in a third modification shown in FIG. May be provided at a position facing the.

Further, in the embodiment, the swash plate type hydraulic motor using the swash plate is exemplified as the hydraulic motor. However, the present invention may be applied to, for example, a swash plate type hydraulic motor or a radial piston type hydraulic motor.

[0056]

As described above in detail, according to the first aspect of the present invention, the supply passage is provided with the supply-side throttle portion for restricting the flow rate of the pressure oil flowing into the hydraulic chamber, and the discharge passage is provided from the hydraulic chamber. Since the exhaust-side throttle section is provided to limit the flow rate of the hydraulic oil discharged to the drain chamber side, when the hydraulic motor is started, the brake piston is released from the brake piston by the hydraulic oil that flows into the hydraulic chamber via the supply passage. And braking can be released. At this time, the supply-side restrictor provided in the supply passage restricts the flow rate of the pressure oil flowing into the hydraulic chamber. Can be prevented, and the reliability can be improved.

According to the second aspect of the present invention, the flow rate of the pressure oil by the supply-side throttle is set to be larger than the flow rate of the pressure oil by the discharge-side throttle. The supply passage, the supply passage, is smaller than the flow rate of the pressure oil discharged from the hydraulic chamber to the drain chamber through the discharge passage and the discharge-side throttle portion.
The flow rate of the pressure oil supplied to the hydraulic chamber via the supply throttle can be increased, and the brake piston can be reliably displaced to the brake release side by the pressure oil supplied to the hydraulic chamber. , The brake can be prevented from being dragged.

According to the third aspect of the present invention, the supply-side throttle section,
Since the discharge side throttle is formed as a thin blade orifice, the influence of temperature change (viscosity change) of the pressure oil passing through the throttle can be almost eliminated, and the pressure oil can be circulated stably in the discharge passage, and the brake performance Can be stabilized.

[Brief description of the drawings]

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

FIG. 2 is an enlarged longitudinal sectional view showing a main part of the brake device in FIG. 1 together with a casing and a part of a valve body.

FIG. 3 is an enlarged longitudinal sectional view of a main part in FIG. 2, showing a state in which a foreign substance mixed in pressure oil blocks a throttle portion of a discharge passage.

FIG. 4 is an enlarged vertical sectional view of a main part of the state in which foreign matter blocking the throttle part has been dropped into the hydraulic chamber, as viewed from the same position as in FIG.

FIG. 5 is an enlarged vertical sectional view of a main part showing a supply passage according to a first modification of the present invention.

FIG. 6 is an enlarged longitudinal sectional view of a main part showing a supply passage according to a second modification of the present invention.

FIG. 7 is an enlarged longitudinal sectional view of a main part showing a discharge passage according to a third modification of the present invention.

[Description of Signs] 1 casing 2 valve body 4 drain chamber 5 output shaft 6 rotor 8 brake device 9 fixed brake plate 10 movable brake plate 11 brake piston 12 hydraulic chamber 15 disc spring (spring) 17 supply passage 22, 31, 41 supply Side throttle section 23 discharge passage 25, 51 discharge side throttle section

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Takashi Shindome, Inventor F650am, Tsuchiura Plant, Tsuchiura-shi, Tsuchiura-shi, Ibaraki Pref. AA48 AA53 AA57 AA77 AA83 AA88 BA01 BA16 BA44 CA43 CA65 CB15 CB17 CB18 CB24 CC03 CC07 CC33 CC35 CC72 CC78 CC82 CD03 CD09 FA11

Claims (3)

[Claims] 1. A casing, an output shaft rotatably supported by the casing, and provided in the casing,
A rotor that rotationally drives the output shaft when pressure oil is supplied from the outside, and a negative-type brake device that applies braking to the rotor when the rotor stops rotating. An annular fixed brake plate provided on the casing side, and a movable brake plate provided on the rotor side so as to overlap the fixed brake plate;
The casing is provided on the inner peripheral surface side of the casing so as to be displaceable in the axial direction, and pressure oil is supplied to a hydraulic chamber defined between the casing and the casing. A brake piston for releasing the engagement, a spring provided between the casing and the brake piston, and constantly biasing the brake piston in a direction in which the fixed brake plate and the movable brake plate frictionally engage with each other; A supply passage provided in the casing for supplying pressurized oil to the casing, and a discharge passage provided in the brake piston for discharging the pressure oil in the hydraulic chamber to the drain chamber side in the casing. In the hydraulic motor having a brake device, a supply-side throttle portion for restricting a flow rate of the pressure oil flowing into the hydraulic chamber is provided in the supply passage, and the discharge passage is provided in the discharge passage. A hydraulic motor having a brake device, comprising: a discharge-side throttle portion for restricting a flow rate of pressure oil discharged from a hydraulic chamber to a drain chamber side. 2. The hydraulic motor having a brake device according to claim 1, wherein the supply-side throttle section is set such that a flow rate of the pressure oil is larger than a flow rate of the pressure oil by the discharge-side throttle section. . 3. The hydraulic motor having a brake device according to claim 1, wherein the supply-side throttle portion and the discharge-side throttle portion are formed as thin blade orifices.