JPS629767B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a clutch master cylinder mounted on a vehicle or the like for operating a clutch device.

Conventionally, clutch devices have been operated either mechanically using a wire or hydraulically using a clutch master cylinder, and recently the latter has been mainly used.

However, since the clutch master cylinder uses the same type of single type brake master cylinder used in brake equipment,
Although the function of the master cylinder itself is suitable for brake use, there are some functions that make it unsuitable for clutch use.

That is, regardless of whether it is for a clutch or a brake, a master cylinder generally includes a cylinder body with a cylinder hole, and an operating piston that is slidably and tightly fitted into the cylinder hole and defines a hydraulic pressure generating chamber. a return spring that urges the actuating piston to the return position; a passage that communicates the hydraulic pressure generating chamber with the actuating fluid reservoir; and a passage that blocks the passage when the actuating piston moves from the return position to the actuation position. It is equipped with a valve device. In the brake master cylinder, when the master cylinder is operated, when the operating piston moves from the operating position to the return position, the reservoir is pumped in response to the negative pressure generated in the hydraulic pressure generation chamber. The hydraulic fluid is allowed to flow into the hydraulic pressure generating chamber from there. For example, in a conventional master cylinder, the supply chamber provided on the outer periphery of the center of the piston is always freely communicated with the hydraulic fluid reservoir, and through the through hole in the flange on the supply chamber side of the lip seal that divides the hydraulic pressure chamber. In addition, the lip seal is deformed by the differential pressure between the negative pressure in the pressure chamber and the atmospheric pressure in the supply chamber, so that hydraulic fluid is supplied from the supply chamber to the hydraulic pressure generation chamber. In this case, the center valve is opened by a differential pressure to supply water from a similar supply chamber.

However, in the clutch master cylinder, 2
If it is possible to depress the clutch twice, the position of the clutch pedal that activates the clutch device will change each time the clutch is pressed, causing the problem that the desired clutch operation cannot be performed with a constant operation. Furthermore, if the hydraulic fluid is excessively pumped out due to double depressing, the operating piston of the clutch operating cylinder connected to the clutch master cylinder will stroke excessively, causing a very serious problem such as the operating piston flying out. becomes.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a clutch master cylinder suitable for use in a clutch. a restriction portion having a small gap between the outer periphery of the working piston and the inner periphery of the cylinder hole so as to constantly throttle and restrict the movement of the working fluid from the reservoir to the hydraulic pressure generating chamber when moving to the position; This is because we have established

FIG. 1 is a side sectional view of a master cylinder for a center valve type clutch, which is an embodiment of the present invention.

In FIG. 1, the master cylinder for the clutch is indicated as a whole by 1, and this master cylinder 1 includes a cylinder body 3 in which a cylinder hole 2 is bored, and an operating piston 4 is slidably inserted into the cylinder hole 2. Although not specifically shown in the drawing for convenience of drawing, the inserted central portion serving as a restricting portion forms a minute gap with the cylinder hole 2, and also defines a hydraulic pressure generating chamber 5 on the left side.

The actuating piston 4 has an elongated hole 6 passing through it in the radial direction.
is formed to extend in the axial direction, and this elongated hole 6 has a shaft-shaped portion 7 that penetrates in the diametrical direction of the cylinder hole 2, which is provided on a bolt (not shown) screwed from the outside of the cylinder body 3. They are mated.

The elongated hole 6 has a groove 10 provided in the circumferential direction that opens at the left end of the elongated hole 6 when the right end of the actuating piston 4 comes into contact with a stopper 9 provided at the open end of the cylinder hole 2 via the ring 8. It communicates with the through hole 11 of the cylinder body 3 through the through hole, and further communicates with the inside of the reservoir device 12 through the through hole 11. Reservoir device 12
Since this is well known, a detailed explanation will be omitted.

A return spring 13 is stretched in a compressed state between the closed end of the cylinder hole 2 and the operating piston 4, and the return spring 13 is moved toward the right in the figure so as to engage the operating piston 4 with the stopper 9. It's pressing. Return spring 13 and operating piston 4
A spring receiver 14 having a substantially cup shape is provided between the
is arranged and abuts one end of the return spring 13 on the collar 15 of the spring receiver 14, and the right end of the cylindrical portion of the spring receiver 14 is press-fitted into the head 16 of the actuating piston 4.

Furthermore, inside the spring receiver 14 there is a valve element 1 urged by a valve spring 18 to seat against a seat 17 formed on the end face of the head 16 of the actuating piston 4.
9 is movably accommodated, and a shaft portion 20 provided on this valve element 19 is slidably inserted through the head 16, and the right end of the shaft portion 20 can abut against the shaft-like portion 7 of the bolt. It's getting old.

When the shaft portion 7 and the shaft portion 20 are in contact with each other and the actuating piston 4 is engaged with the stopper 9, the hydraulic pressure generating chamber 5 is formed through the hole 22 of the spring receiver 14 and the valve element 19.
A passage 21, an elongated hole 6, a groove 10 provided in the shaft portion 20,
It communicates with the inside of the reservoir device 12 via the through holes 11 in sequence. That is, like the conventional one,
The biasing force of the valve spring 18 against the valve element 19 in the seating direction is made smaller than the biasing force of the return spring 13 that causes the operating piston 4 to engage the stopper 9, so that during operation, the operating piston 4 When the valve element 19 moves in the direction of engaging the stopper 9, the valve element 19 comes into contact with the bolt shaft 7 just before the actuating piston 4 and the stopper 9 engage, and in this state, the actuating piston 4 further moves into the stopper 9. When moved to the side, the valve element 19 is moved away from the seat 17 by further moving the actuating piston 4 while compressing the valve spring 18 under the biasing force of the return spring 13 . Then, the valve element 19 is separated from the shaft portion 7 of the bolt, that is,
When the valve element 19 is seated on the seat 17 by the biasing force of the valve spring 18, the pressure on the hydraulic pressure generation chamber 5 side and the pressure on the elongated hole 6 side are act in opposition to each other, and when the pressure in the hydraulic pressure generation chamber 5 is positive, the pressure on the elongated hole 6 side is atmospheric pressure, so the biasing force due to the pressure difference in the same direction as the biasing force of the valve spring 18 is generated. As a result, the valve element 19 is more strongly seated on the seat 17, and conversely, when the pressure in the hydraulic pressure generation chamber 5 is negative, a biasing force due to a pressure difference opposing the biasing force of the valve spring 18 acts. Thus, when the seating force of the valve element 19 against the seat 17 becomes small and the negative pressure becomes particularly strong, the valve element 19 separates from the seat 17. Note that even if the valve element 19 is moved away from the seat 17, liquid movement from the reservoir device 12 side to the hydraulic pressure generating chamber 5 side is prevented by a throttling action, which will be described later. Further, the hydraulic pressure generating chamber 5 communicates through a connecting hole 23 with a clutch operating cylinder (not shown) that swings a clutch release arm of a clutch device (not shown).

In addition, in FIG. 1, 24 and 25 are conventionally well-known lip seal type sealing members, and 26
1 and 2 each illustrate a push rod connected to a clutch pedal (not shown).

In particular, in the above-described embodiment, between the sealing members 24 and 25 of the actuating piston 4, the elongated hole 6 and the through hole 11 do not communicate freely, but communicate with each other through a passage having a throttling action. The diameter is made slightly smaller than the inner diameter of the cylinder hole 2, and when the actuating piston 4 engages with the stopper 9, the groove 1
As shown in the figure, this groove 10 also has a considerably small passage area to prevent air bleeding operations such as pressure feeding when mounted on an actual vehicle from becoming difficult. As can be understood from the above, the restricting portion extends from the groove 10 to the sealing member 25 side at least in the axial direction by a length corresponding to the effective stroke of the actuating piston 4 (the passage 1
It is necessary that the opening 1 be provided in all the parts facing each other over the entire stroke of the working piston 4), and in consideration of manufacturing convenience, it may be provided in the entire area between the sealing members 24 and 25 (excluding the groove 10).

The operation of the master cylinder 1 described above will be described below.

Now, in the clutch device, assuming that the clutch plate is in frictional engagement with the flywheel, that is, in the clutch connected state, the master cylinder 1 is in the inactive state, and each member is in the illustrated position, that is, the axis of the valve element 19. The portion 20 is in contact with the shaft-shaped portion 7, and
The actuating piston 4 engages with the stopper 9, and the inside of the hydraulic pressure generating chamber 5 becomes pressureless.

Next, when the driver depresses the clutch pedal to release the frictional engagement of the clutch plate of the clutch device for gear change or the like, that is, to disengage the clutch, the operating piston 4 is pressed by the push rod 26 and the return spring is pressed. 13, and due to this movement of the actuating piston 4, the valve element 19 seats on the seat 17, cutting off communication between the elongated hole 6 and the hydraulic pressure generating chamber 5, and also disconnects the groove 10 from the valve element 19. Communication with the through hole 11 is almost cut off. At this time, elongated hole 6
Communication between the elongated hole 6 and the through hole 11 is achieved only by a gap between the outer circumferential surface of the intermediate portion of the actuating piston 4 and the inner circumferential surface of the cylinder hole 2. By reducing this gap, the communication between the elongated hole 6 and the through hole 11 is Communication is restricted.

After this state, when the operating piston 4 moves further to the left, high pressure is generated in the hydraulic pressure generating chamber 5, the operating cylinder swings the clutch release arm, and the clutch device becomes in the disconnected state.

When the driver completes the necessary operations during disengagement of the clutch device, he gradually releases the clutch pedal until it reaches the inactive position, in other words, he removes his foot from the clutch pedal. At this time, the actuating piston 4 gradually moves to the right in accordance with the movement of the push rod 26, and finally the shaft portion 20 of the valve element 19 comes into contact with the shaft portion 7, and the valve element 19 is separated from the seat 17. However, the pressure in the hydraulic pressure generating chamber 5, which had been gradually reduced until then, is released. The actuating piston 4 then returns to the position in which it engages the stopper 9. In response to these operations, the clutch release arm of the clutch device swings, and the clutch device changes from a disconnected state to a half-clutch state to a fully connected state.

In the above-described series of operations, when the actuating piston 4 suddenly moves from the left to the right in the cylinder hole 2 due to the sudden return of the clutch pedal, negative pressure is generated in the hydraulic pressure generating chamber 5, and the valve Element 19
is separated from the seat 17 due to the negative pressure in the hydraulic pressure generation chamber 5, but at this time, the elongated hole 6 is a gap between the through hole 11, the outer peripheral surface of the actuating piston 4, and the inner peripheral surface of the cylinder hole 2. Since the gap has a throttling effect, the movement of the hydraulic fluid from the elongated hole 6 side to the hydraulic pressure generation chamber 5 side is restricted, and even if the valve element 19 is separated from the seat 17, the movement of the hydraulic fluid from the elongated hole 6 side is restricted. Almost no working fluid flows from the pump to the hydraulic pressure generating chamber 5 side.

Therefore, in the master cylinder 1 described above, in the process of operating from the disconnected state to the connected state, even if the return operation is stopped midway and the clutch pedal is depressed again to move the actuating piston 4 to the left, in other words, , even if the clutch pedal is depressed twice, no excess hydraulic fluid will flow into the hydraulic pressure generating chamber 5, so even after the clutch pedal is depressed twice, the amount of depression of the clutch pedal when the clutch device is completely disengaged will be reduced. is, 2
It will be the same as before the double step, and 2
Even if you want to obtain a half-clutch state after depressing twice, the pedal position before and after depressing twice will be the same.
The clutch device can be actuated by a certain operation. Furthermore, since excess hydraulic fluid is not delivered to the clutch operating cylinder, the piston of the clutch operating cylinder will not be overstroked, improving reliability or safety.

In the above-mentioned embodiment, an example of a center valve type clutch master cylinder was shown, but an example of a conventional type master cylinder will be briefly explained below.

FIG. 2 is a side sectional view of a conventional master cylinder according to another embodiment of the present invention.

In FIG. 2, the conventional master cylinder is indicated as a whole by 30, and the master cylinder 30 has an actuating piston 33 slidably fitted into a cylinder hole 32 formed in a cylinder body 31.

Large diameter portions 34 and 35 that slide on the inner wall of the cylinder hole 32 are formed at the left and right end portions of the actuating piston 33, and the intermediate portion is reduced to form an annular chamber 36 between the inner wall and the inner wall of the cylinder hole 32. diameter. In particular, since the large diameter portion 34 is just a restricting portion having a slightly smaller diameter than the cylinder hole 32, a gap is formed between the large diameter portion 34 and the inner wall of the cylinder hole 32 to the extent that it exhibits a throttling effect as described later. Note that the above-mentioned gap is not shown in the figure for convenience of drawing.

A well-known lip seal type sealing member 37 is attached to the left end of the actuating piston 33, and is prevented from coming off by a spring receiver 38 adjacent to the sealing member 37. A hydraulic pressure generating chamber 39 is formed between the operating piston 33 and the closed end of the cylinder hole 32, and a return spring 40 in a pre-compressed state is tensioned.
0, the actuating piston 33 has returned to its return position in which it engages the stopper 42 via the annular ring 41.

When the operating piston 33 is in the return position, a loosening hole 43 is formed in the cylinder body 31 and is located to the left of the sealing member 37 and communicates the hydraulic pressure generating chamber 39 with a reservoir (not shown). , a through hole 44 communicating between the annular chamber 36 and the reservoir is located in the cylinder body 3.
1 is drilled.

In addition, in Fig. 2, 45 is a sealing member;
Reference numeral 6 indicates a dustproof boot, and 47 indicates a push rod, and the piping, operating means, etc. for the master cylinder 30 are the same as those shown in FIG.

To explain the operation of this embodiment, when it is not in operation, the operating piston 4 is in the return position by the return spring 40, and the hydraulic pressure generating chamber 39 is in communication with the reservoir through the loosening hole 43 and is in a pressureless state. .

When the driver depresses the clutch pedal, the push rod 47 presses the actuating piston 33.
moves to the left against the return spring 40. After the movement starts, when the left end of the sealing member 37 passes the loosening hole 43, communication between the hydraulic pressure generating chamber 39 and the reservoir is cut off, and as the actuating piston 33 moves further to the left, pressure is applied to the hydraulic pressure generating chamber 39. is generated and transmitted to the clutch operating cylinder. In addition,
Although the connecting portions of the piping are not shown, it is assumed that the same connecting portions as in the example of FIG. 1 are formed.

When the clutch device is fully disengaged, the large diameter portion 34 of the actuating piston 33 has moved sufficiently to the left beyond the release hole 43. Therefore, even if the pedal is pressed twice, the hydraulic pressure generation chamber 39 and the loosening hole 4
3 is restricted by the throttling effect created by the gap between the large diameter portion 34 and the cylinder hole 32, so that even if negative pressure occurs in the hydraulic pressure generating chamber 39, the annular chamber 36 or the The hydraulic fluid does not move from the hole 43 toward the fluid pressure generation chamber 39.

Therefore, in this conventional type master cylinder 30 as well, it is possible to prevent excessive hydraulic fluid from flowing into the hydraulic pressure generation chamber 39 due to double depressing, etc., and to maintain a constant depressing position of the clutch pedal that operates the clutch device. Moreover, excessive stroke of the piston of the clutch operating cylinder can be prevented, improving reliability and safety. In the embodiment shown in FIG. 2, the through hole 44 is formed when the master cylinder 30 is mounted on an actual vehicle.
It plays an important role during air purge work to remove air present in the piping system including the annular chamber 36.

As described above, according to the present invention, when the working piston moves from the working position to the return position, the movement of the working fluid from the reservoir side toward the hydraulic pressure generation chamber is restricted, so that the It is possible to prevent excessive hydraulic fluid from flowing into the pressure generating chamber, and even if it does flow, it is only a small amount, and the position of the clutch pedal that activates the clutch device is stabilized, and the piston of the clutch operating cylinder is This makes it possible to prevent excessive strokes and to obtain a master cylinder suitable for use as a clutch.
Further, according to the present invention, since the configuration for producing such an effect is such that a restricting portion is provided in the actuating piston, it can be implemented without making any particular changes to the cylinder body, thereby improving practicality. Good.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a center valve type clutch master cylinder which is an embodiment of the present invention, and FIG.
The figures each show a side sectional view of a conventional clutch master cylinder according to another embodiment. 1, 30... Master cylinder, 4... Working piston, 5, 39... Hydraulic pressure generation chamber.

Claims (1)

[Claims] 1. A cylinder body having a cylinder hole, an actuating piston that is slidably and tightly fitted into the cylinder hole to define a hydraulic pressure generation chamber, a return spring that urges the actuating piston to a return position, and the hydraulic piston. A master cylinder includes a passage communicating a pressure generating chamber with a hydraulic fluid reservoir, and a valve device that shuts off the passage when the working piston moves from a return position to an operating position. so as to constantly restrict movement of the hydraulic fluid from the reservoir to the hydraulic pressure generating chamber when moving from the reservoir to the return position;
A clutch master cylinder is provided with a restriction portion that reduces a gap between the outer periphery of the actuating piston and the inner periphery of the cylinder hole.