JPS6225887B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in master cylinders.

The structure of a conventional master cylinder will be explained with reference to FIGS. 1, 2 and 3.

FIG. 1 shows a conventional master cylinder in side sectional view, and FIG.
This is a view of the groove 2b of the piston 2 in FIG. 1, and FIG. 3 is an enlarged view of the center valve 3 in FIG. cylinder 1a
A piston 2 is fitted into the cylinder 1a to enable sliding movement in the axial direction of the cylinder 1a, and a rod 2a that is linked to a clutch pedal (not shown) is in contact with the piston 2. .

A pin 1f screwed onto the body 1 is fitted into a groove 2b cut into the piston 2, and a reservoir (not shown) is inserted into the piston 2.
The connecting hole 1e that communicates with the groove 2b of the piston 2 communicates with the groove 2b of the piston 2.

As shown in an enlarged view in FIG. 3, a valve body 31 is fitted into an axial cylinder 2c bored in the piston 2 so as to be able to slide in the axial direction. At the end on the side of the chamber 1b, a ring-shaped valve 33 made of elastic material such as rubber is fitted, and the valve 33 is axially aligned with respect to the valve seat 2d exposed to the displacement chamber 1b in the piston 2. A planar valve sealing surface 33a is formed at the end, and the valve body 3
A perforation 31a that communicates with the groove 2b is formed in the cylindrical part that fits into the cylinder 2c in 1, and a perforation 31b formed radially inward of the valve sealing surface 33a is connected to the perforation 31a. It's communicating.

The spring 32b sandwiched between the spring receiver 32 fitted to the piston 2 and the valve body 31 is
The valve body 31 is biased toward the end face 2d. In addition,
32a is a perforation.

The spring 1d is configured to bias the piston 2 toward the rod 2a, and the displacement chamber 1b communicates with a clutch device of the vehicle via a connecting hole 1c and a clutch pipe (not shown).

To explain the operation of the configurations shown in FIGS. 1, 2, and 3 above, as shown in the figure, when the clutch pedal is released, the piston 2 is moved to the shaft end of the cylinder 1a by the urging force of the spring 1d. In the state where the valve body 31 is pushed back to the end, the valve body 31 comes into contact with the pin 1f, and the valve seal face 33a floats above the end face 2d while the valve body 31 compresses the spring 32b. There is. As a result, the reservoir is connected to the connection hole 1
e, the groove 2b, and the perforations 31a and 31b communicate with the displacement chamber 1b, and the displacement chamber 1b is sufficiently replenished with the hydraulic fluid in the reservoir.

When the clutch pedal is depressed from the above-mentioned released state, the piston 2 is pressed and moved toward the connection hole 1c, and the valve body 31 is moved to the pin 1f.
As a result, the spring 32b urges the valve body 31 toward the end surface 2d,
As a result, the valve seat 33a is seated on the end surface 2d, and communication between the reservoir and the displacement chamber 1b is closed.

As the piston 2 is further depressed from this state, the operating pressure within the displacement chamber 1b increases,
This increased operating pressure causes the vehicle's clutch system to engage.

When the clutch pedal is released from the above state, the piston 2 should move to the spring 1.
The valve body 31 is pushed back toward the rod 2a by the biasing force d, and the valve body 31 comes into contact with the pin 1f again, and the valve seat 33a floats up from the end face 2d.

At this time, the position in the axial direction of the piston 2 that corresponds to the valve seat 33a floating above the end surface 2d is as follows:
The position of the piston 2 where the valve seal surface 33a is seated on the end surface 2d when the piston 2 is depressed does not necessarily correspond to the position of the piston 2 where the valve seal surface 33a begins to float from the end surface 2d. This shows a phenomenon in which the valve sealing surface 33a shifts toward the rod 2a from the position of the piston 2 seated on the end surface 2d by being depressed.

This means that when operating the vehicle clutch,
The depressed position of the clutch pedal where the clutch action begins and the depressed position of the clutch pedal where the clutch action ends are different as the clutch action is released, and the driver's feeling of clutch operation is as follows: It is more desirable to match the clutch pedal operation positions of both.

Hereinafter, the effect when the clutch pedal is released and the valve sealing surface 33a floats up from the end surface 2d will be explained based on experimental results.

FIG. 4 shows a further enlarged view of the end surface 22d and valve seal surface 33a in FIG. 3, and shows the state in which the valve seat 33a is about to rise from the end surface 2d. If the hydraulic oil is supercharged into the displacement chamber 1b due to double depression of the clutch pedal, etc., the clutch pedal is released and the valve seal surface 33a rises from the end surface 2d. Even if the piston 2 reaches the piston position, due to the supercharging,
A residual pressure P exists in the displacement chamber 1b, and as shown in FIG. This causes a phenomenon of pushing out to the 2d side. As a result, the valve sealing surface 33a is the end surface 2d.
Following this movement, the communication between the displacement chamber 1b and the reservoir is still closed, which causes a delay in the release of the clutch action. This has been experimentally confirmed.

In addition, as shown by the two-dot broken line in FIG. 4, there is also a valve in which the valve seal surface has a configuration of 33a', but the above-mentioned phenomenon also occurs in this type. .

SUMMARY OF THE INVENTION It is an object of the present invention to provide a master cylinder with improved clutch operation as described above.

To explain the present invention based on an embodiment, FIG. 5 shows the center valve 3 used in the conventional master cylinder in FIG. 1 replaced with a center valve 4 as an embodiment of the present invention. This is a side sectional view of the center valve 4 in the case where the center valve 4 is
In the figure, center valve 3 in FIG.
The difference is that the valve body 31 and valve 33 in FIG. 3 are newly replaced with a valve body 41 and valve 43, and the other configurations are the same as in FIG. 3.

As in FIG. 3, the valve body 41 in FIG. 5 is fitted in the cylinder 2c so as to be able to slide in the axial direction. 31
b, the valve 43 is fitted onto the valve body 41 in a state where the radially protruding portion of the flange 41b cut into the valve body 41 is wrapped, and the valve sealing surface of the valve 43 is The outer peripheral portion of 43a is chamfered 43d to form a valve seal surface 4.
The outer diameter at 3a is smaller than the outer diameter of flange 41c.

Note that 43e is a seat for the spring 32b.

In the configuration shown in FIG. 5 above, its operation will be explained. When the clutch pedal is depressed, the valve body 41 separates from the pin 1f, similar to what was explained in FIGS. 1 and 3. Then, the spring 32b urges the valve body 41 toward the end surface 2d, and as a result, the valve sealing surface 43
A is seated on the end surface 2d, closes communication between the displacement chamber 1b and the reservoir, and exerts a clutch action.

In response to the above action, when the clutch pedal is released and the clutch pedal reaches a position corresponding to the normal position where it should float above the end surface 2d of the valve sealing surface 43a, the displacement chamber 1b In the present invention, the same residual pressure p due to the double depression etc. as explained in FIG. Since the outer diameter is smaller than the outer diameter of the flange 41c, the phenomenon of pushing out the outer peripheral portion of the valve sealing surface 43a significantly as in the conventional operation shown in FIG. 4 does not occur. There is.

This action will be explained below with reference to FIG.

FIG. 6 is an explanatory diagram showing a state when the valve 43 in FIG. 5 floats from the end surface 2d, and
3 is pressed from its outer periphery and back surface by the residual pressure p remaining in the displacement chamber 1b, and due to this pressing, the valve 43, which has an elastic force, tries to be swept away in the direction of the end face 2d. Due to the existence of the flange 41c and the fact that the outer diameter of the valve sealing surface 43a is smaller than the outer diameter of the flange 41c, the flow of deformation due to the pressure becomes a flow 43b (indicated by a two-dot broken line); The portion shaded by the flange 41c by the flange 43b forms a water stop area 43c, which can be considered similar to a water stop area in the flow of viscous fluid.

As a result, if the valve seal surface 43a is brought as close as possible to the radially inner portion of the cutoff area 43c that is not affected by deformation by the flow 43b, the pushing action of the radially outer peripheral portion of the valve seal surface 43a is minimized. The stop area 43c is located at least on the inner diameter side of the flange 41c than the outer diameter of the flange 41c.

That is, the flange 41c protrudes in the radial direction,
As a result, the portion of the valve 43 that is not pushed out even by the internal pressure p (the cutoff area 43c) extends to the valve sealing surface 43a, making it difficult to deform the valve sealing surface 43a.

Further, if the function of this flange 41c is explained from another angle, it will be as shown in FIG. 7. In addition,
FIG. 7 shows the valve 43 and flange 41c in FIG. 6.

The valve 4 outside the outer diameter a of the flange 41c
3, the force exerted by the pressure within the displacement chamber 1b in the axial direction is balanced with the pressure p acting on the back surface 43e of the valve 43 and the pressure p acting on the chamfered portion 43d.

Furthermore, the pressure p acting in the axial direction on the back surface 43e of the valve 43 on the inner diameter side of the outer diameter a of the flange 41c is received by the flange 41c.

Therefore, the valve sealing surface 43a hidden on the inner diameter side of the outer diameter a of the flange 41c becomes less susceptible to deformation due to the internal pressure p, and as a result, deformation of the valve sealing surface 43a is prevented.

Based on the above considerations, the valve 43 installed in the configuration shown in FIG. 5 has the outer diameter of the valve sealing surface 43a smaller than the outer diameter of the flange 41c, , the experimental results when used in the master cylinder shown in Fig. 1 show that the depression position of the clutch pedal, which corresponds to the valve sealing surface 43a floating above the end face 2d, approaches the normal depression position by about 70%, which is an improvement. We are getting results.

Note that the outer peripheral portion of the valve sealing surface 43a is
Although it has a chamfered structure 43d, this shape may have an arcuate cross section in the axial direction, or may have a stepped structure.

As is clear from the above description, the master cylinder of the present invention has a flange 4 on the valve body 41.
1c and has an elastic valve 43 fitted to the flange 41c, the valve sealing surface 4
By providing the outer diameter of the flange 3a inside the outer diameter of the flange 41c, the internal pressure p in the displacement chamber 1b is reduced.
As a result, deformation of the valve seal surface 43a caused by this can be made very small.

As a result, the clutch pedal operation position when the clutch pedal is depressed and the clutch action begins, and the clutch operation position when the clutch action ends when the clutch pedal is released are brought closer to each other. This makes it possible for the driver to have a better feeling when operating the clutch.

Note that this master cylinder can also be used for brakes.

[Brief explanation of the drawing]

FIG. 1 shows a conventional master cylinder in side sectional view, and FIG. 2 shows the groove 2b of the piston 2 in FIG. 3 is an enlarged view of the center valve 3 in FIG. 1, and FIG. 4 is an enlarged view of the valve seat 33 in FIG.
FIG. 5 is an explanatory view of the effect when a floats from the end surface 2d, and FIG. 5 is an example of the present invention.
The case where the improved valve body 41 and valve 43 are attached to the center valve 3 in FIG. 3 in place of the valve body 31 and valve 33 in FIG. 3 is shown in the same side sectional view as in FIG. 3. FIG. 6 is an explanatory view of the operation when the valve seat 43a in FIG. 5 floats from the end surface 2d. or,
FIG. 7 is an explanatory diagram of the operation of FIG. 6. The symbols used in the examples are as follows,
Among the symbols used in each example, the same symbols indicate the same materials. 1: Body, 1a: Cylinder, 1b: Displacement chamber, 1c and 1e: Connection hole, 1d: Spring, 1f: Pin. 2: Piston, 2a: Rod, 2b: Groove, 2c: Cylinder, 2d: End surface. 3 and 4: Center valve, 31 and 41: Valve body, 31a, 31b, 4
1a and 41b: perforation, 41c: flange. 3
2: Spring receiver, 32a: Perforation. 33 and 4
3: Valve, 33a, 33a' and 43a: Valve seal surface, 43b: Flow, 43c: Stop area, 43d: Chamfer, 43e: Seat, P: Residual pressure in displacement chamber 1b.

Claims (1)

[Claims] 1. A piston connected to a pedal is fitted into a cylinder bored in the body so as to be able to slide in the axial direction, and a valve with elasticity is fitted into a valve body. a valve sealing surface is formed at the end of the valve in the axial direction, the piston forms an end surface relative to the valve sealing surface in the axial direction, and an axis between the piston and the valve body a spring disposed between the two directions biases the valve sealing surface toward the end surface; the body is provided with a stopper member that selectively abuts the valve body; and the cylinder and the piston A displacement chamber is formed to enclose the valve body, the end surface, and the spring, and the valve includes: a: when the valve sealing surface is seated on the end surface, the displacement chamber and the reservoir close,
When the valve sealing surface is floating above the end surface,
communicating between the displacement chamber and the reservoir; b: when the piston is depressed, the stopper material and the valve body are separated from each other, and the valve sealing surface is closed by the biasing force of the spring; is seated on the end surface, and c: when the piston is released,
In the above structure in which the valve seal surface is floated from the end surface by the contact between the stopper material and the valve body, in the valve body, the valve seal surface is caused to float from the end surface A radially protruding flange is fixed to the opposite side in the axial direction, and the fitting of the valve is such that the valve encloses the radial outer circumference and both axial end surfaces of the flange portion, and the outer circumference of the valve sealing surface. The master cylinder has an outer diameter smaller than the outer diameter of the flange.