JPH055642U - Master cylinder sealing device - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] Until the internal pressure of the oil chamber reaches a predetermined pressure, a minute amount of oil flow in the oil chamber is allowed to prevent the internal pressure of the oil chamber from rising. [Structure] A bearing 45 and a piston 8 are inserted into a cylinder body 5, and the bearing is a cylinder chamber 6 and an oil chamber 2.
6, and the cylinder chamber is connected to the tank 1 through the low pressure side passage 14 provided in the piston and is connected to the brake cylinder 2 through the passage 3 provided in the cylinder body, and the valve 10 is movable in the center of the bearing. In a master cylinder that selectively opens and closes the cylinder chamber to the low pressure side passage 14 or the oil storage chamber, a housing 50 is provided in the valve, and a flow passage 52 that connects the low pressure side passage and the oil chamber to the housing 50. 53 is provided, a valve body 54 is movably provided to these, and a small hole 55 that communicates the oil chamber with the flow path is formed so that the oil in the oil chamber flows to the minute amount cylinder chamber up to a predetermined pressure in the oil chamber. When the internal pressure rises above a predetermined pressure, the flow path is blocked by the internal pressure.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to a master cylinder sealing device, and more particularly to a brake master cylinder sealing device that operates hydraulic brakes provided on agricultural tractors and other vehicles.

[0002]

[Prior Art]

 As a conventional brake master cylinder device, for example, one disclosed in Japanese Utility Model Laid-Open No. 59-116261 is known.

This master cylinder device takes a long piston process after the tank port is closed in the process of thrusting the piston into the cylinder chamber, and various braking forces from a small braking force to a large braking force are generated. It is designed to be easily obtained by pedal operation.

The structure is such that the tank port of the hydraulic pressure source and the brake port on the brake cylinder side are connected in the cylinder chamber, the piston interlocking with the pedal is movably inserted in the cylinder, and the piston is mounted on the outer periphery of the piston. The elastic seal ring provided opens and closes the tank port and cylinder chamber.

A pair of these members are provided in the cylinder housing, the pair of cylinder chambers are connected by a communication hole, and a ball that is opened and closed by the end of the piston is movably incorporated in the mouth end of the communication hole. ..

However, the above structure has the following problems.

First, when the piston is pushed in, the ball is pushed by the end of the piston to open the valve, but the ball surface is scratched by the piston while the piston is repeatedly pushed, and the ball sealability is increased. May deteriorate, oil may leak, and the desired braking force may not be generated.

Secondly, the elastic seal ring provided on the outer circumference of the piston moves together with the piston and is hooked on the mouth end of the tank port at that time, or comes into sliding contact with the inner circumference of the cylinder chamber, so that the elastic seal ring is used during long-term use. The ring will be worn out or damaged, and the desired sealing effect will not be obtained.

In addition, when the pressure on the brake cylinder side suddenly rises, this pressure may cause the elastic seal ring to protrude or be displaced.

For this reason, the present application has developed a master cylinder device for a brake having improved sealing properties (Japanese Patent Laid-Open No. 63-46963).

In this master cylinder device, a piston and a valve are provided in a cylinder chamber in series, a passage for connecting a hydraulic pressure source and a brake cylinder is provided in a piston, and a valve head provided at one end of the valve is provided at the mouth end of this passage. An oil chamber is provided at the back of the valve so that it can be opened and closed freely, and this oil chamber is isolated from the cylinder chamber by a bearing and a seal provided on the outer periphery of this bearing, and a poppet provided at the other end of the valve. It is a valve body bearing that is abutted on the seat of the valve body in a freely openable and closable manner.

According to this master cylinder device, when the pedal or the like is depressed and the piston interlocked with the pedal is depressed, the passage in the piston is blocked by the valve head of the valve, and when the piston is further depressed, the valve body of the valve moves into the oil chamber. Is opened in the cylinder chamber, and oil equivalent to the piston intrusion volume is guided from the oil chamber to the brake cylinder, and pressure corresponding to the stroke of the piston acts on the brake cylinder to operate it.

[0013]

[Problems to be solved by the device]

 However, in the above master cylinder device, the oil chamber is sealed by the bearing, the seal, and the valve body of the valve when the piston is not pushed in and is not operating.In this state, the outside temperature rises and the vehicle travels. When the oil temperature in the oil chamber rises due to heat generation inside, the oil expands and the internal pressure rises. Therefore, if you try to push in the piston by pedaling as it is, the operating force will increase and the operating feeling will change, which may cause a malfunction.

Therefore, an object of the present invention is to provide a sealing device suitable for use of a master cylinder for a brake cylinder, which allows a minute flow rate of oil in the oil chamber to prevent the internal pressure of the oil chamber from rising until the internal pressure of the oil chamber reaches a predetermined pressure. Is to provide.

[0015]

[Means for Solving the Problems]

 In order to achieve the above object, the structure of the present invention is such that a fixed bearing and a movable piston are inserted in the cylinder body, and the bearing divides the cylinder chamber and the oil chamber into the cylinder chamber. Is connected to the tank via a low-pressure passage in the piston and to the brake cylinder via a passage in the cylinder body.A valve is movably inserted in the center of the bearing, and the valve is In the master cylinder that selectively opens and closes the binder chamber to the low pressure side passage or the oil chamber, a housing is provided in the valve, and a flow path connecting the low pressure side passage and the oil chamber is provided in the housing. A valve body that opens and closes the flow passage is provided in the flow passage at a movable position, and a small hole that communicates the oil chamber with the flow passage is formed in the housing. Allows a small amount of oil in the oil chamber to flow into the cylinder chamber through the small hole, the flow passage, and the outer peripheral gap of the valve body, and when the internal pressure rises above a predetermined pressure, the valve body moves due to the internal pressure. It is characterized by blocking the flow path.

[0016]

[Action]

 When the internal pressure rises due to the rise in the oil temperature in the oil chamber, the oil in the oil chamber escapes to the minute low pressure side through the small holes, the flow path and the outer peripheral gap of the valve body.

When the internal pressure of the oil chamber rises above a predetermined pressure, this internal pressure pushes the valve body and shuts off the flow path.

[0018]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings.

A master cylinder 4 is provided in the middle of a passage 3 connecting the tank 1 as a hydraulic pressure source and the brake cylinder 2.

The master cylinder 4 moves into two cylinder bodies 5, a cylinder chamber 6 provided in the cylinder body 5, a piston 8 slidably inserted in the cylinder chamber 6, and a cylinder chamber 6 that is the same as the cylinder chamber 6. It consists of a poppet type valve 10 inserted freely.

When a vehicle such as an agricultural tractor is provided with a pair of left and right wheels, a pair of brake cylinders 2 and 2 is provided as shown in the figure in order to brake each wheel, and each brake cylinder 2 and 2 is operated. Therefore, although a pair of pistons and the like are provided, for example, in a motorcycle such as an autobike, only the rear wheels or the front wheels need to be braked.

The piston 8 is formed with a radial passage 12 connecting the passage 3 on the tank 1 side and the cylinder chamber 6 and a low pressure side passage 14 in the axial direction, and at the mouth end of the passage 14, a trumpet-type sheet. 16 are formed.

The outer end of the piston 8 is interlocked with a brake pedal on the vehicle body side, and when the brake pedal is depressed with a foot or the like, the piston 8 is simultaneously or selectively pushed.

Seals 18 and 19 are provided on the outer circumference of the piston 8, respectively, and a seal member 20 such as a dust seal and an oil seal is provided at the tip of the cylinder body 5, and the cylinder body 5 and the piston 8 are connected to each other. Boots 21 and 21 are attached between them.

Caps 22 and 23 are screwed onto the rear end of the cylinder body 5, and the outer circumference thereof is sealed with a seal 25.

An oil chamber 26 is provided inside the caps 22 and 23 and the valve body 5. The oil chamber 26 is sealed by the shaft sealing device A according to the present invention and the valve 10 inserted in the shaft sealing device A.

The shaft sealing device A includes a bearing 45 and a seal 24 made of an O ring fitted in an annular groove of the bearing 45.

In the oil chamber 26, the tip end side of the valve 10 guided in the center of the bearing 45 is movably inserted into the cylinder chamber 6, and the valve head 32 is attached to the trumpet-type sheet 16 of the piston 8. Opposite to open and close freely.

The valve 10 is provided with a poppet-type valve head 32 at the tip and a poppet-type valve body 34 at the lower part, and further, a passage 28 formed by a notch, a groove, etc. is formed in the body portion. The cylinder chamber 6 is connected to the oil chamber 26.

Springs 36 and 38 are provided on the front end side and the rear end side of the valve 10, respectively, and the valve 10 is held at the neutral position by the springs 36 and 38.

In this neutral state, the valve head 32 is slightly separated from the seat 16 and opens the passage 14 to the cylinder chamber 6, while the valve body 34 abuts on the seat of the bearing 45. The cylinder chamber 6 is isolated from the oil chamber 26 behind the valve.

The cylinder chambers 6 are always connected to the brake cylinders 2, respectively.

When a pair of piston 8 and valve 10 are provided and the oil chamber 26 is always connected, it is necessary to provide the valve element 34 in the valve 10, but in the case where there is only one piston and valve. Alternatively, when the oil chambers 26 in the valve bodies 5 and 5 are not connected, the transformation body 34 is not always necessary.

The valve 10 is hollow, and housings 50 and 51 are provided in the valve 10. Flow paths 52 and 53 are formed in the housings 50 and 51 to connect the low pressure side passage 14 and the oil chamber 26, and a poppet type valve body 54 is movably inserted into the flow path 53.

The valve body 54 is normally biased by a spring 57 in the direction of opening the valve head.

A small hole 55 that connects the oil chamber 26 and the flow path 53 is formed in the housing 50, and a small hole 56 for a pilot that guides the oil pressure of the oil chamber 26 is formed on the back surface of the valve body 54.

Next, the operation will be described.

In the illustrated state, the tank 1 as a hydraulic pressure source and the brake cylinder 2 communicate with each other, so that the brake cylinder 2 does not operate at a low pressure.

Next, in order to turn the vehicle to the left, for example, in the figure, when the upper brake cylinder 2 is operated and the lower brake cylinder 2 is released, the following operation is performed.

First, the left brake pedal (not shown) is depressed with a foot, and the upper piston 8 is pushed rightward.

At this time, the seat 16 of the low pressure side passage 14 contacts the valve head 32, and the passage 14 and the cylinder chamber 6 are shut off.

Next, when the piston 8 is further pushed in, the cylinder chamber 6 and the oil chamber 26 are communicated with each other through the passage 28, and the oil in the cylinder chamber 6 and the oil chamber 26 is moved upward through the piston intrusion amount volume integral passage 3. Is supplied to the brake cylinder 2 and the piston rod of the brake cylinder 2 moves to brake the corresponding wheel.

The pressure at this time corresponds to the moving amount of the piston 8, and is adjusted from a small braking force to a large braking force according to the moving amount of the piston 6.

On the other hand, since the valve body 34 of the valve in the lower valve body blocks the passage 38, the oil in the upper cylinder chamber 6 is supplied only to the upper brake cylinder 2 and the oil in the lower cylinder body 6 is lowered. The brake cylinder 2 does not work because it is still connected to the tank 1.

When it is desired to turn right, the lower brake cylinder 2 is operated in reverse to the above, and the upper brake cylinder 2 is released to the tank 1.

On the other hand, when it is desired to brake both the left and right wheels at the same time, both the left and right brake pedals are depressed to cause the two pistons 8 to move to the right at the same time.

Therefore, the same amount of oil in the cylinder chambers 6, 6 and the oil chambers 26, 26 is simultaneously supplied to the brake cylinders 2, 2 to brake each wheel with the same pressure.

At this time, since the oil chambers 26, 26 are in communication with each other, they have the same pressure, and the pressures of the brake cylinders 2, 2 have the same pressure and are balanced.

By the way, the oil chamber 26 is sealed by the valve body 34 when the piston 8 and the valve 10 are stopped in a non-operating state as shown in FIG. It slightly communicates with the cylinder chamber 6 via the outer peripheral gap of the body 54 and the flow path 52.

Therefore, when the oil in the oil chamber 26 expands and the internal pressure rises to a predetermined pressure due to an increase in the outside air temperature, heat generated while the vehicle is traveling, etc., the oil in the oil chamber 26 is discharged into the small hole 55 and the oil passage 43. , 52 to the cylinder chamber 6.

Therefore, it is possible to prevent the operation force when the piston 8 is pushed in by the pedal operation from increasing, the operation feeling does not change, and the danger of representing an operation error is prevented.

On the other hand, when shifting from this state to the operation state of pushing the piston 8 and the valve 10, the internal pressure of the oil chamber 26 rises above a predetermined pressure, and the internal pressure acts on the valve body 54 through the pilot small hole 56. Then, it is pressed to the left, the valve body 54 moves to block the oil passage 52, and the oil flows only from the passage 28.

[0053]

[Effect of the device]

 The present invention has the following effects.

When the internal pressure rises when the volume of the oil chamber does not change and when the outside air temperature rises, the fluid in the oil chamber flows out to the low-pressure side through the small holes that are minute passages.

Therefore, even if the operating state in which the volume of the oil chamber is changed from the non-operating state is changed, the risk of causing malfunction or malfunction is prevented because the internal pressure of the oil chamber is always set within a predetermined pressure range. ..

It is possible to prevent the internal pressure of the oil chamber from rising above a predetermined pressure due to an increase in the oil temperature or the like, and thus the operation force by the pedal operation of the piston or the valve pushed into the oil chamber does not increase, and a constant operation is performed. I can maintain my sense.

[Brief description of drawings]

FIG. 1 is a sectional view of a master cylinder according to the present invention.

[Explanation of symbols]

 1 Tank 2 Brake Cylinder 3 Passage 5 Cylinder Body 6 Cylinder Chamber 8 Piston 10 Valve 14 Low Pressure Side Passage 26 Oil Chamber 45 Bearing 50 Housing 52, 53 Flow Channel 54 Valve Body 55 Small Hole

Claims (1)

[Claims for utility model registration] [Claim 1] A fixed bearing and a movable piston are inserted in the cylinder body, and the bearing defines a cylinder chamber and an oil chamber in the cylinder body. It is connected to the tank through a low-pressure side passage provided and is connected to the brake cylinder through a passage provided in the cylinder body. In a master cylinder that selectively opens and closes a side passage or the oil chamber, a housing is provided inside the valve, and a flow passage that connects the low pressure side passage and the oil chamber is provided inside the housing, and the flow passage is connected to the passage. A valve body that opens and closes the flow passage is movably provided, and a small hole that communicates the oil chamber with the flow passage is formed in the housing. Allows a small amount of oil in the oil chamber to flow into the cylinder chamber through the hole, the flow passage, and the outer peripheral gap between the valve body, and when the internal pressure rises above a predetermined pressure, the internal pressure moves the valve body and Master cylinder sealing device to shut off.