JP2006144927A - Hydraulic control device of wet type multiple-disc brake - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic control device of a wet type multiple-disc brake including a service brake which is operated at the time of running of a vehicle and a parking brake which is operated when the service brake is not operative, in which the structure of a hydraulic device for actuating the hydraulically operating service brake and parking brake is simplified so as to reduce the cost of the device, to make it easy to control the hydraulic device and to improve the maintainability. <P>SOLUTION: In the wet type multiple-disc brake including the parking brake which engages an axle-shaft side part with an axle-housing side part when the service brake is not operative, the parking brake is released by applying hydraulic oil pressure to a parking brake piston when the service brake is operative, and the parking brake is operated when the service brake is not operative. A service brake oil system and a parking brake oil system are connected to a common brake hydraulic oil system. By switching a selector valve installed in the hydraulic oil system, the operation of the service brake and the parking brake is switched. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  INDUSTRIAL APPLICABILITY The present invention is applied to various vehicle brake devices including industrial vehicle brake devices such as forklifts, and provides service by pressing a mating plate attached to the axle housing side and a friction plate attached to the axle shaft side. The present invention relates to a hydraulic control device for a wet multi-plate brake that is configured to operate a brake and includes a parking brake that locks an axle shaft side to an axle housing side when a service brake is not operated.

As a brake device used in wheeled industrial vehicles such as forklifts and special work vehicles,
The service brake is operated by pressing the mating plate attached to the axle housing side and the friction plate attached to the axle shaft side, and the axle shaft side is set to the axle housing side when the service brake is not operating. A wet type multi-plate brake having a parking brake that is locked to the vehicle is often used.

  Such a wet multi-plate brake meshes with a spline on the frame support side that is bolted to the outer peripheral flange of the axle housing and the inner periphery of the vehicle body side frame as disclosed in, for example, Japanese Patent Application Laid-Open No. 2000-161403. A plurality of mating plates and a plurality of friction plates engaged with a spline on the brake hub side bolted to a wheel hub fixed to the axle end of the axle shaft are connected by a hydraulic piston driven by hydraulic oil. It is configured to connect and disconnect.

JP 2000-161403 A

A wet multi-plate brake used as a brake device used in a wheeled industrial vehicle such as a forklift or a special work vehicle is a service brake that operates when a normal vehicle travels, and is disclosed in Japanese Patent Application Laid-Open No. 2000-161403. ), The mating plate on the axle housing side and the friction plate on the axle shaft side are configured to come in and out of contact with a hydraulic piston driven by hydraulic oil, The parking brake for stopping the vehicle when it is not operated is installed separately from the service brake and is operated by a hydraulic system different from the service brake, or is constituted by a mechanical brake.

For this reason, in this prior art, a hydraulic system for operating the service brake is provided independently, and when using a hydraulically operated parking brake, the hydraulic system for operating the parking brake is connected to the hydraulic system for the service brake. Are separately provided, the structure of the hydraulic device for operating the service brake and the parking brake is complicated, the device cost is increased, the control of the hydraulic device is complicated, and there is a problem in maintainability.
And so on.

  In view of the problems of the prior art, the present invention is a wet multi-plate brake including a service brake that is operated when a vehicle is running and a parking brake that is operated when the service brake is not operated. An object of the present invention is to provide a hydraulic control device for a wet multi-plate brake that simplifies the structure of a hydraulic device to be operated to reduce the device cost, facilitates the control of the hydraulic device, and further improves maintainability.

The present invention achieves such an object, and is configured to operate a service brake by press-contacting a mating plate attached to an axle housing side and a friction plate attached to an axle shaft side. In the wet multi-plate brake provided with a parking brake for locking the axle shaft side to the axle housing side when the brake is not operated,
The service brake is configured so that the hydraulic pressure supplied from the service brake oil system to the service brake oil chamber is applied to the service brake piston so that the mating plate and the friction plate are pressed against each other.
When the service brake is operated, the parking brake causes the hydraulic pressure supplied from the parking brake oil system to the parking brake oil chamber to act on the parking brake piston to separate the mating plate and the friction plate. And when the service brake is inoperative, the parking brake is operated by pressing the mating plate and the friction plate by releasing the hydraulic pressure from the parking brake oil chamber,
Further, the service brake oil system and the parking brake oil system are connected to a common brake hydraulic system, and the operation of the service brake and the parking brake is switched by switching a switching valve installed in the hydraulic system. It is characterized by comprising.

  According to this invention, the service brake is applied to the service brake piston by applying the operating hydraulic pressure supplied to the service brake oil chamber to the mating plate attached to the axle housing side and the friction plate attached to the axle shaft side. In addition, the service brake oil system and the parking brake oil system are configured to release the parking brake by applying the operating hydraulic pressure supplied to the parking brake oil chamber to the parking brake piston when the service brake is operated. 1 can be used by connecting the service brake oil system and the parking brake oil system to a common brake hydraulic system and switching a switching valve installed in the hydraulic system. One Both the service brake and the parking brake in hydraulic system from the hydraulic source can be operated.

As a result, the structure of the hydraulic device is simplified and the device cost can be reduced as compared with the conventional technology in which the hydraulic system for operating the service brake and the hydraulic system for operating the parking brake are separately provided.
Further, since the hydraulic system for operating the service brake and the hydraulic system for operating the parking brake are common, it is possible to control the hydraulic device only by switching the switching valve, thereby facilitating the control of the hydraulic device. Maintenance of the hydraulic device is also facilitated and maintainability is improved.

In this invention, preferably, the brake hydraulic fluid system connected to the service brake fluid system and the parking brake fluid system is connected to the same hydraulic power source as a work device drive oil system that operates a work device such as a cargo handling device. Then, the hydraulic oil from the hydraulic power source is branched from the work device drive oil system and connected to the brake hydraulic system.
With this configuration, the hydraulic oil from one hydraulic source can be used for both the handling and switching of the parking brake and the service brake, and specially for the operation of the parking brake and the service brake. No hydraulic source is required. Thereby, the hydraulic device for parking brake and service brake can be further simplified.

In this invention, it is preferable that the service brake oil including surplus oil of the service brake oil system includes the service brake oil chamber when the service brake that supplies the operation brake oil to the service brake oil system is operated. It is configured to circulate in the system.
According to this structure, when the service brake is in an operating state, the surplus oil of the pedal pressure assist hydraulic booster is circulated through the service brake oil chamber side, so that the mating plate and the friction plate when the service brake is operated By absorbing the frictional heat caused by the pressure contact with the circulating hydraulic fluid as described above, overheating of the service brake can be suppressed.

In the invention, preferably, the parking brake oil system is operated by a pressure switch that detects a pressure of the parking brake oil system and maintains the parking brake oil system at a constant pressure. A switching valve for controlling the supply of hydraulic oil in the oil system is provided.
If comprised in this way, it will become possible to hold | maintain the pressure of the hydraulic oil path to a parking brake oil chamber to the reference | standard pressure set to this pressure switch with the pressure switch and the switching valve operated by this pressure switch. As a result, the pressure on the parking brake oil chamber side can be maintained at the reference pressure (allowable pressure) at all times while the parking brake is released, and the pressure drop due to the occurrence of oil leakage due to long-time release of the parking brake can be prevented. .

In the invention, preferably, a switching valve for switching between draining oil from the parking brake oil chamber and shutting off the draining oil is installed in the parking brake oil system, and the switching valve is connected to the hydraulic oil tank. An orifice for restricting the oil drainage passage is installed in the oil drainage passage.
With this configuration, the orifice is installed in the downstream portion of the switching valve of the hydraulic oil drainage passage from the parking brake oil chamber, so that it becomes necessary to use the parking brake due to a failure during traveling of the vehicle. In this case, the opening of the hydraulic fluid from the parking brake oil chamber is loosened by the throttle action of the orifice so that the parking brake can be smoothly inserted, and the parking brake is suddenly inserted and the vehicle is suddenly decelerated. It is possible to avoid the occurrence of dangerous situations.

According to the present invention, the service brake oil system and the parking brake oil system are configured to release the parking brake by applying the operating hydraulic pressure supplied to the parking brake oil chamber to the parking brake piston when the service brake is operated. The same hydraulic fluid system can be used, and the service brake fluid system and the parking brake fluid system are connected to a common brake hydraulic fluid system, and one switching valve installed in the hydraulic fluid system is switched. Both the service brake and the parking brake can be operated by a hydraulic system from the hydraulic source.
As a result, the structure of the hydraulic device is simplified and the device cost can be reduced as compared with the conventional technology in which the hydraulic system for operating the service brake and the hydraulic system for operating the parking brake are separately provided, Since the hydraulic system for operating the service brake and the hydraulic system for operating the parking brake are common, it is possible to control the hydraulic device only by switching the switching valve, thereby facilitating the control of the hydraulic device. Maintenance is also facilitated and maintainability is improved.

  Also, the brake hydraulic system connected to the service brake fluid system and the parking brake fluid system is connected to the same hydraulic source as the work device drive oil system that operates the work device such as a cargo handling device, and the operation from the hydraulic source is performed. By configuring the oil to branch from the work device drive oil system and connect to the brake hydraulic system, the hydraulic oil from one hydraulic power source can be used for the cargo handling device, the parking brake, and the service brake. It can be used for both operation switching and does not require a special hydraulic source for the operation of the parking brake and service brake. Thereby, the hydraulic device for parking brake and service brake can be further simplified.

  Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this example are not intended to limit the scope of the present invention only to specific examples unless otherwise specified. Only.

FIG. 3 is a longitudinal sectional view of a wet multi-plate brake for forklifts to which the present invention is applied, and FIG. 4 is a view taken along the line AA of FIG.
In FIGS. 3 to 4, 300 is a wet multi-plate brake, 1 is an axle housing on the vehicle body side, and 2 is an axle shaft inserted through the center of the axle housing 1. Reference numeral 10 denotes an annular frame support, the inner peripheral side of which is fixed to the flange portion 1a of the axle housing 1 by a plurality of bolts 10a, and the outer peripheral side is fixed to the vehicle body side frame 50 by a plurality of bolts 51. .
Reference numeral 4 denotes a wheel hub. The inner peripheral side is fixed to a flange portion 2a formed on the shaft end portion of the axle shaft 2 by a bolt 2b, and the outer peripheral side is fastened together with an outer end flange 6a of a brake hub 6 described later. Are fixed to the rim 7a of the wheel by a plurality of bolts 7.

Reference numeral 3 denotes a bearing that pivotally supports the wheel hub 4 on the outer periphery of the end portion of the axle housing 1 and includes two roller bearings capable of receiving a radial load and a thrust load. 3c is a seal ring interposed between the inner periphery of the wheel hub 4 and the outer periphery of the end portion of the axle housing 1, and is disposed between the two bearings 3 and 3. 3a is a retainer for fixing the bearing 3 with a bolt.
6 is an annularly formed brake hub, 9 is an annularly formed brake cover, 9a is an annularly formed center cover, and the brake cover 9 and the center cover 9a are fastened together by a plurality of bolts to the frame. It is fixed to the support 10.
An external spline is formed inside the brake hub 6 and a plurality of friction plates 8 are engaged with the external spline so as to be movable in the axial direction. On the other hand, an inner tooth spline is formed on the inner periphery of the center cover 9a, and a mating plate 13 is engaged with the inner tooth spline so as to be movable in the axial direction so as to alternate with the friction plate 8.

  Reference numeral 16 denotes a parking brake piston which is fitted to the inner periphery of the frame support 10 so as to be capable of reciprocating in the axial direction. Reference numeral 15 denotes a parking spring comprising a compression spring installed between the inner side surface of the frame support 10 and the side surface of the parking brake piston 16, and the parking brake piston 16 is driven by the spring force of the parking spring 15 when the vehicle is parked. The friction plate 8 and the mating plate 13 are pressed against each other via the retainer 14a.

  Reference numeral 14 denotes a service brake piston provided in the frame support 10. As shown in FIG. 4, the service brake piston 14 is fitted to the frame support 10 so as to be axially movable in cylinders 10 b formed at six locations on the half circumference side in the circumferential direction. As shown in FIG. 4, the parking spring 15 is installed on the same circumference as the service brake piston 14 at a portion where the service brake piston 14 is not provided.

20a is a service brake oil chamber that the service brake piston 14 faces. The service brake oil chamber 20a is introduced with hydraulic oil that acts on the service brake piston 14 from the inlet oil passage 20c and the oil passage 20e when the service brake is operated. The service brake piston 14 presses the mating plate 13 and the friction plate 8 to brake the wheel.
Reference numeral 20b denotes a parking brake oil chamber facing the back surface of the parking brake piston 16. When the service brake is operated as described above, hydraulic oil is introduced into the oil chamber 20b through the oil passage 20d, and the spring force of the parking spring 15 is increased. Accordingly, the parking brake piston 16 is pushed back to deactivate the parking brake.

The present invention operates the service brake by applying the hydraulic pressure supplied to the service brake oil chamber to the service brake piston as described above, and applies the hydraulic pressure supplied to the parking brake oil chamber to the parking brake piston. This relates to the hydraulic control device in the wet multi-plate brake device configured to release the parking brake.
FIG. 1 is a hydraulic circuit diagram of a hydraulic control device in a wet multi-plate brake device for forklifts according to an embodiment of the present invention, and FIG. 2 is an electric circuit diagram.

1 and 2, reference numeral 100 denotes an engine, 65 denotes a hydraulic pump driven by the engine 100, and 67 denotes a hydraulic oil tank that stores hydraulic oil. Further, 64 is a steering wheel, 63 is a steering control valve, 60 is a cargo handling device control valve, 61 is hydraulic fluid that has passed through the cargo handling device control valve 60 and the steering control valve 63 and service brake and parking brake control described later. This is a diversion valve for diverting to the switching valve V ₁ 70 and the switching valve V ₂ 69.
73 is a hydraulic booster for stepping force assist, which converts the stepping force of a brake pedal (not shown) into hydraulic pressure, amplifies it, and supplies it to the service brake oil chamber 20a. 71 is a pressure adjusting valve of the parking brake system, and 75 is a check valve.

In such a hydraulic control device, the hydraulic oil pumped by the hydraulic pump 65 is sent to the cargo handling device control valve 60 through the hydraulic oil passage 66, enters the flow dividing valve 61 from the cargo handling device control valve 60, and The diverter valve 61 divides the hydraulic fluid on the steering control valve 63 side into the hydraulic fluid for controlling the service brake and parking brake according to the present invention.
The brake control hydraulic fluid divided by the branch valve 61 is sent to the inlet port of the switching valve V ₁ 70 through the hydraulic oil passage 77. Reference numeral 31 denotes an accumulator connected to the hydraulic oil passage 77.

Next, when the operation of the parking brake in the wet multi-plate brake 300 (FIGS. 1 and 2) is released, the parking brake switch 82 in FIG. 2 is operated to switch the contact from z to y. Then, the coil of relay R ₁ 80 is excited and the contact point e is brought into contact. Thereby, the excited solenoid of the switching valve V ₂ 69 and the switching valve V ₂ 69 is shifted to 69a side, the oil discharge side is closed.
Further, at the same time when the contact e of the relay R ₁ 80 is contacted, the contact g of the relay R ₂ 81 is contacted, the solenoid of the switching valve V ₁ 70 is excited, and the switching valve V ₁ 70 is moved to the 70c side. Shifted to.

As a result, the inlet port of the switching valve V ₁ 70 is connected to the parking brake side, and the operating oil passes through the oil passage 85 and passes through the oil passage 20d in the wet multi-plate brake 300 (FIG. 1) to the parking brake oil chamber. By entering into 20b, the parking brake oil chamber 20b is filled with hydraulic oil, and the hydraulic oil pushes back the parking brake piston 16 against the spring force of the parking spring 15.
By this operation, the mating plate 13 and the friction plate 8 are disconnected, the parking brake is deactivated, that is, released, and the forklift can be operated and traveled.

74 is a pressure switch provided in the hydraulic oil passage 85 to the parking brake oil chamber 20b. When the operating oil pressure on the parking brake oil chamber 20b side exceeds a preset reference pressure (allowable pressure), FIG. Thus, the contact point 74a of the pressure switch 74 is in contact and energized, and the coil of the relay R ₂ 81 is excited to switch the contact point h to contact.
The switching of such relay _R 2 81, the switching valve _V 1 70 solenoid is energized switching valve _V 1 70 of is shifted to 70d side, the hydraulic oil in the parking brake oil chamber 20b side through the oil passage 85 Can be supplied. Therefore, the pressure of the hydraulic oil passage 85 to the parking brake oil chamber 20 b is held at the reference pressure set in the pressure switch 74.
As a result, the pressure on the parking brake oil chamber 20b side can be maintained at the reference pressure (allowable pressure) at all times while the parking brake is released as described above, and oil leakage occurs when the parking brake is released for a long time. It is possible to prevent a pressure drop due to.

When the parking brake is released as described above, the switching valve V ₁ 70 is shifted to the 70d side, so that the hydraulic oil that is diverted by the diverter valve 61 and passes through the hydraulic oil passage 77 is The pressure is supplied from the valve V ₁ 70 to the hydraulic booster 73 for assisting the pedaling force through the oil passage 76a. In the pedal pressure assisting hydraulic booster 73, the hydraulic pressure inside the hydraulic oil master cylinder 73a is changed according to the pedaling force of the brake pedal, and is supplied to the service brake oil chamber 20a through the oil passages 85a and 85b.
As a result, the service brake piston 14 presses the mating plate 13 and the friction plate 8 and the service brake is activated.

  At this time, the surplus oil of the pedal pressure assist hydraulic booster 73 passes through the oil passage 76b and the oil passage 76c and circulates through the service brake oil chamber 20a side circulating oil chamber 30. As a result, the frictional heat generated by the pressure contact between the mating plate 13 and the friction plate 8 when the service brake is operated is absorbed by the hydraulic oil that circulates as described above, thereby suppressing overheating of the service brake.

When the parking brake is used, the parking brake switch 82 is operated to switch the contact from y to z. Then, the excitation of the relay R ₁ 80 is cut off, the contact f is brought into contact, the switching valve V ₂ 69 is shifted to the 69b side, and the parking brake oil drain passage is opened.
With this operation, the hydraulic oil in the parking brake oil chamber 20 b is discharged from the oil passage 85 into the hydraulic oil tank 67 through the switching valve V ₂ 69 and the drain oil passage 76.
Here, since the orifice 72 is provided at the downstream portion of the switching valve V ₂ 69 of the oil discharge passage 76, the hydraulic oil is discharged from the parking brake oil chamber 20 b by the throttle action of the orifice 72. It is done slowly.
By discharging the working oil from the parking brake oil chamber 20b, the parking brake piston 16 presses the mating plate 13 and the friction plate 8 by the spring force of the parking spring 15, and the parking brake is activated.

As described above, when the parking brake needs to be used due to a failure during traveling of the vehicle, the operating oil in the parking brake oil chamber 20b is discharged and the parking brake is activated as described above. since installed an orifice 72 in the switching valve V ₂ 69 downstream site of the oil discharge passage 76 of the hydraulic oil from the parking brake oil chamber 20b, the hydraulic fluid from the parking brake oil chamber 20b by the diaphragm action of the orifice 72 The parking brake can be smoothly inserted by releasing the opening of the parking brake smoothly, and it is possible to avoid the occurrence of a dangerous situation in which the parking brake is suddenly inserted and the vehicle is suddenly decelerated.

According to this embodiment, the mating plate 13 attached to the axle housing 1 side and the friction plate 8 attached to the axle shaft 2 side are used to supply the operating hydraulic pressure supplied to the service brake oil chamber 20a to the service brake piston 14. The service brake is operated by acting on the parking brake, and the hydraulic pressure supplied to the parking brake oil chamber 20b is applied to the parking brake piston 16 so as to release the parking brake. A part of the hydraulic oil for use is used as hydraulic oil for both the parking brake and the service brake by switching the _two switching valves V ₁ 70 and V ₂ 69.

  Therefore, according to this embodiment, the hydraulic oil from one hydraulic source can be used for both the cargo handling device and the operation and switching of the parking brake and the service brake, and is specially used for the operation of the parking brake and the service brake. No need for a hydraulic source. Thereby, the hydraulic circuit for the parking brake and the service brake can be simplified.

  According to the present invention, in a wet multi-plate brake including a service brake that is operated when the vehicle is running and a parking brake that is operated when the service brake is not operated, the hydraulic service brake and the hydraulic device that operates the parking brake are provided. The structure can be simplified and the device cost can be reduced, the control of the hydraulic device can be facilitated, and the hydraulic control device for the wet multi-plate brake with improved maintainability can be provided.

1 is a hydraulic circuit diagram of a hydraulic control device in a wet multi-plate brake device for forklifts according to an embodiment of the present invention. It is an electric circuit diagram in the said Example. 1 is a longitudinal sectional view of a wet multi-plate brake to which the present invention is applied. It is an AA arrow line view of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Axle housing 2 Axle shaft 3 Bearing 8 Friction plate 13 Mating plate 14 Service brake piston 15 Parking spring 16 Parking brake piston 20a Service brake oil chamber 20b Parking brake oil chamber 60 Control valve for cargo handling device 61 Dividing valve 65 Hydraulic pump 67 Actuation Oil tank 69 selector valve V ₂
70 Switching valve V ₁
71 Pressure regulating valve 73 Hydraulic booster for pedaling force assist 100 Engine 300 Wet multi-plate brake

Claims (5)

The service brake is operated by pressing the mating plate attached to the axle housing side and the friction plate attached to the axle shaft side, and the axle shaft side is connected to the axle when the service brake is not operated. In wet multi-plate brakes equipped with a parking brake that locks to the housing side,
The service brake is configured so that the hydraulic pressure supplied from the service brake oil system to the service brake oil chamber is applied to the service brake piston so that the mating plate and the friction plate are pressed against each other.
When the service brake is operated, the parking brake causes the hydraulic pressure supplied from the parking brake oil system to the parking brake oil chamber to act on the parking brake piston to separate the mating plate from the friction plate. And when the service brake is inoperative, the parking brake is operated by pressing the mating plate and the friction plate by releasing the hydraulic pressure from the parking brake oil chamber,
Further, the service brake oil system and the parking brake oil system are connected to a common brake hydraulic system, and the operation of the service brake and the parking brake is switched by switching a switching valve installed in the hydraulic system. A hydraulic control device for a wet multi-plate brake, characterized in that it is configured as follows.   The brake hydraulic fluid system connected to the service brake fluid system and the parking brake fluid system is connected to the same hydraulic power source as a work device drive oil system that operates a work device such as a cargo handling device. 2. The hydraulic control device for a wet multi-plate brake according to claim 1, wherein the hydraulic oil is branched from the working device drive oil system and connected to the brake hydraulic fluid system.   The surplus oil of the service brake oil system is configured to circulate in the service brake oil system including the service brake oil chamber when the service brake is supplied to the service brake oil system by the switching valve. 2. The hydraulic control apparatus for a wet multi-plate brake according to claim 1.   Supplying to the parking brake oil system a pressure switch for detecting the pressure of the parking brake oil system and maintaining the pressure of the parking brake oil system at a constant pressure, and operating the parking brake oil system by operating the pressure switch 2. A hydraulic control device for a wet multi-plate brake according to claim 1, further comprising a switching valve for controlling the engine. The parking brake oil system is provided with a switching valve for switching between draining oil from the parking brake oil chamber and shutting off the draining oil, and the oil draining path is connected to the draining path connecting the switching valve and the hydraulic oil tank. 2. The hydraulic control device for a wet multi-plate brake according to claim 1, wherein an orifice for performing a throttling action is installed.

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