JPS6116660B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a two-stage actuation type master cylinder as a hydraulic pressure generation source for a hydraulic clutch device or brake device mounted on a vehicle or the like.

When a clutch or brake device is operated by hydraulic pressure, a large amount of fluid is required even at low pressure during dry operation until the clutch or brake starts to work, and a small amount and high pressure is required for effective operation after the clutch or brake starts to work. It is generally known that it requires

For this reason, the master cylinder as a source of hydraulic pressure has a small diameter hole and a large diameter hole arranged in series in the cylinder body, and a piston having a small diameter part and a large diameter part is inserted into each hole, and the end of the small diameter hole and the large diameter part are inserted into each hole. A main pressure chamber is formed between the small diameter part of the piston and an auxiliary pressure chamber is formed between the small diameter part and the large diameter part of the piston, and a return spring is inserted into the main pressure chamber to maintain the piston under the auxiliary pressure. The piston is biased toward the outer wall of the chamber, and a flow hole and a valve device are provided in the small diameter portion of the piston to enable fluid flow and adjustment of fluid pressure between the main pressure chamber and the auxiliary pressure chamber. Additionally, it is generally known that a valve device is provided between the auxiliary pressure chamber and the reservoir to prevent the hydraulic pressure in the auxiliary pressure chamber from exceeding a certain value.

However, the conventional master cylinder has a complicated valve system between the main pressure chamber and the auxiliary pressure chamber.
It is difficult to manufacture and may cause failure, and although the pressure in the auxiliary pressure chamber cannot exceed a certain level, if that pressure remains and you try to increase the pressure in the main pressure chamber, the residual pressure will cause resistance. This has drawbacks such as a decrease in operating efficiency.

In view of the above-mentioned problems, the present invention simplifies the structure of the valve device between the main pressure chamber and the auxiliary pressure chamber, facilitates manufacturing, eliminates the possibility of causing failure, and improves the residual pressure in the auxiliary pressure chamber. The purpose of this is to improve operating efficiency by completely eliminating the

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a side sectional view of the clutch master cylinder, and FIG. 2 is a side view of the piston in FIG. 1.

In the figure, cylinder body 2 of master cylinder 1
A small-diameter hole 3 and a large-diameter hole 4 are arranged in series inside, and a piston 5 is fitted therein. The piston 5 has a small diameter hole 3
A small diameter portion 6 that fits into the large diameter hole 4 and a large diameter portion 7 that fits into the large diameter hole 4 are connected by a connecting portion 9 that has a long hole 8 and has a smaller diameter than the small diameter portion 6, and are integrated into the cylinder body 2. It is designed to be able to slide left and right inside. Further, the small diameter portion 6 of the piston 5 has a valve seat 10 at its end.
A shaft portion 11 is provided in a protruding manner. Further, the outer periphery of the small diameter portion 6 forms a sliding surface that is in close contact with the inner circumferential surface of the small diameter hole 3 with an extremely small gap.
A groove 12 and a passage groove 13 are provided in this surface so as to communicate with each other. (In the figure, the groove 12 is provided around the entire circumference of the small diameter portion 6, but it may be provided only in the range that communicates with the passage groove 13.) 14 is provided on the shaft portion 11 side of the small diameter portion 6. The attached sealing member 15 is a sealing member attached to the connecting portion 9 side of the large diameter portion 7. A main pressure chamber 16 is formed in the small diameter hole 3 on the left side of the sealing member 14, and an auxiliary pressure chamber 17 is formed in the large diameter hole 4 on the right side of the small diameter portion 6. Further, a through hole 18 from the shaft portion 11 to the long hole 8 is provided in the small diameter portion 6, and the valve member 2 has a valve body 19 mounted in the hole 18.
0 in a slidable manner. 21 and 22 are valve members 2
0, when the valve body 19 is not in contact with the valve seat 10, the main pressure chamber 16 and the auxiliary pressure chamber 17
It communicates with The valve body 19 is biased by a valve spring 25 between it and a spring receiver 24 having a small hole 23 attached to the shaft portion 11, and is pressed onto the valve seat 10 with an appropriate force. But piston 5
When the piston 5 is biased by the return spring 26 inserted into the main pressure chamber 16 and is located on the right side of the cylinder body 2 as shown in FIG. The right end of the valve member 20 comes into contact with the shaft-like member 27 which is loosely fitted into the shaft member 8 and projects into the auxiliary pressure chamber, and an appropriate gap is created between the valve seat 10 and the valve body 19, and the through hole is formed as described above. The main pressure chamber 16 and the auxiliary pressure chamber 17 are communicated via 21 and 22.
Reference numeral 28 denotes a small hole provided in the cylinder body 2, which opens toward the groove 12 of the small diameter portion 6 and communicates with the reservoir (not shown) when the piston 5 is in the position shown in FIG. are doing. Furthermore, a valve device 30 is installed on the reservoir side via a passage 29. This valve device 30 has a valve member 32 pressed against a valve seat 33 with a predetermined pressure via a valve spring 31.
When the pressure inside the auxiliary pressure chamber 17 reaches a predetermined pressure or higher, the valve member 32 is pushed up against the pressing force of the valve spring 31 to open the valve and the fluid flows out to the reservoir side through the escape hole 34. It's getting old. The small hole 28 and the valve device 30 are covered by a fitting 35 for communicating with the reservoir. A fluid discharge hole 36 is provided at the left end of the main pressure chamber 16, and a ring 37 and a stopper 38 for determining the right position of the piston 5 are provided at the right end of the auxiliary pressure chamber 17. Further, a push rod 39 is installed between the right end of the piston 5 and a clutch pedal (not shown). 40 is a stopper for the connector 35.

Next, the operation of the above structure will be explained.

Fig. 1 shows the non-operating state when the clutch pedal is not depressed, and the piston 5 is biased by the return spring 26, and its right end is connected to the ring 37.
The stopper 38 is in contact with the stopper 38 via the stopper 38. In this state, as described above, the right end of the valve member 20 comes into contact with the shaft member 27 projecting into the auxiliary pressure chamber 17, and the valve body 19 and the valve seat 10 are separated. Therefore, the main pressure chamber 16 and the auxiliary pressure chamber 17 communicate with each other via the through holes 21 and 22. Further, the auxiliary pressure chamber 17 and the reservoir communicate with each other via the grooves 12 and 13 and the small hole 28. Since both pressure chambers 16 and 17 communicate with the reservoir in this way, the hydraulic fluid filled in these chambers is in a pressureless state (more precisely, equal to atmospheric pressure).

When the clutch pedal is depressed and the piston 5 is pushed through the push rod 39, the piston 5 moves forward against the repulsive force of the return spring 26, and its small diameter portion 6 closes the opening of the small hole 28, thereby creating a gap between the reservoir and the auxiliary pressure chamber. Communication with 17 is cut off. Next, as the piston 5 moves further forward, each pressure chamber 16,
17 begins to decrease, pressure is generated in each chamber, and from the auxiliary pressure chamber 17 to the main pressure chamber 16,
The hydraulic fluid begins to move from the main pressure chamber 16 to the discharge port 36.

At this time, the amount of liquid discharged from the discharge port 36 is the sum of the volume reductions of both the pressure chambers 16 and 17, and the liquid pressure is the effective receiving pressure of both the large and small diameter portions 6 and 7. It is the value divided by the sum of the areas (however, the sliding resistance of the piston 5 and the repulsive force of the return spring 26 are ignored).

After that, the piston 5 moves forward further, and both pressure chambers 1
When the pressure inside 6, 17 rises and reaches the valve opening pressure of the valve device 30, the valve member 32 moves away from the valve seat 33 against the repulsive force of the valve spring 31, and the liquid inside the auxiliary pressure chamber 17 flows through the escape hole. 34 to the reservoir side, and the pressure increase in the auxiliary pressure chamber 17 is stopped.

Even if the pressure increase in the auxiliary pressure chamber 17 stops, the pressure increase in the main pressure chamber continues, and as the piston 5 moves forward, the right end of the valve member 20 fitted to the shaft portion 11 separates from the shaft member 27. Therefore, the valve element 19 is pressed against the valve seat 10 by the pressure difference between the pressure chambers 16 and 17 acting simultaneously and the biasing force of the valve spring 25, thereby closing the valve.
Thereafter, the pressure in the main pressure chamber 17 increases rapidly as the piston 5 moves forward.

After the valve device 30 opens, when the piston 5 moves forward slightly and the right end of the small diameter portion 6 passes the opening of the small hole 28, the auxiliary pressure chamber 17 and the reservoir communicate through the small hole 28, and the auxiliary pressure The pressure within chamber 17 is released. The valve device 30 is therefore closed.

When the piston 5 is moved further forward thereafter, hydraulic fluid is discharged from the discharge hole 36, but the discharge amount is the volume reduction of the main pressure chamber 16, and the pressure reduces the acting force that presses the piston 5 to the small diameter portion 36. (However, the sliding resistance of the piston 5 and the repulsive force of the return spring 26 are ignored.)

Therefore, compared to when the piston 5 started moving forward, the discharge amount of the hydraulic fluid is smaller and the discharge pressure is higher. Furthermore, since there is no residual pressure within the auxiliary pressure chamber 17, this operation can be carried out efficiently.

Next, when the clutch pedal is released and the pressing force acting on the piston 5 via the push rod 39 is gradually reduced, the piston 5 is moved by the pressure in the main pressure chamber 16 and the repulsive force of the return spring 26. and started retreating.

At this time, the volume of the auxiliary pressure chamber 17 increases,
The working fluid is replenished from the small hole 28 for that amount. Further, the discharged hydraulic fluid returns to the main pressure chamber 16.

When the piston 5 further retreats, the small hole 28 is closed by the small diameter portion 6, and the flow of hydraulic fluid into the auxiliary pressure chamber 17 is cut off. However, since the piston 5 is urged by the return spring 26, it continues to move backward while generating vacuum pressure in the auxiliary pressure chamber 17.

At this time, a small amount of hydraulic fluid flows into the auxiliary pressure chamber 17 from the small hole 28 through a small gap between the small diameter portion 6 and the large diameter hole 3. Further, before the piston 5 is completely retracted to the return position, the valve member 20 is moved to the shaft member 27.
The valve opens upon contact with the main pressure chamber 16 , and the hydraulic fluid in the main pressure chamber 16 flows into the auxiliary pressure chamber 17 . In this way, the auxiliary pressure chamber 17 that had been generating vacuum pressure is restored to atmospheric pressure.

When the piston 5 is completely retracted to the return position, the small hole 28 communicates with the auxiliary pressure chamber 8 through the grooves 12, 13, and excess hydraulic fluid flows into the reservoir through the grooves 12, 13 and the small hole 28. Returning, the master cylinder 1 enters the above-mentioned non-operating state.

Next, another embodiment of the present invention will be explained with reference to FIG. FIG. 3 is a side sectional view of the brake master cylinder.

In the one shown in FIG. 3, the small diameter hole 3 of the cylinder body 2 of the master cylinder 1 in the first embodiment is extended, and a floating piston 45 is slidably fitted into the small diameter hole 3. Sealing members 46 and 47 are attached to both ends of the floating piston 45, and a first pressure chamber 48 and a second pressure chamber 49 are formed on the right side and the left side, respectively. Furthermore, a return spring 19' that biases the piston 5 to the right is inserted into the first pressure chamber 48, and a return spring 50 that biases the floating piston 45 to the right is inserted into the second pressure chamber 49. has been done. Therefore, the repulsive force of the return spring 50 is
9', a stopper 51 is provided on the cylinder body 2 to prevent the floating piston 45 from advancing beyond a predetermined position to the right. Reference numeral 52 is a loosening hole that communicates between the second pressure chamber 49 and the reservoir, and 53 is a hydraulic fluid replenishment hole that communicates between the intermediate space 54 of the floating piston 45 and the reservoir. In this embodiment, the valve device 55 is provided with a check valve 55 for replenishing liquid when the pedal is pressed twice.

The operation (particularly of the main parts) is the same as that of the first embodiment. This proves that it is unique for use in brakes. When the piston 5 is pressed and moved to the left, the hydraulic fluid in the first pressure chamber 48 is discharged from its discharge hole (not shown) and the pressure is increased. When this pressure overcomes the repulsive force of the return spring 50, the floating piston 45 is pushed and moves to the left, blocking the loosening hole 52 and increasing the pressure in the second pressure chamber 49. Discharge. In this way, even if the piston 5 moves further to the left, the hydraulic pressures in the first pressure chamber 48 and the second pressure chamber 49 are balanced, and pressurized fluid is discharged to the two brake devices to operate the devices.

As mentioned above, the master cylinder of the present invention has a simple structure of the valve device provided in the small diameter portion of the piston, so it is easy to manufacture, operates reliably, and is trouble-free.
Furthermore, when high pressure is generated, the residual pressure in the auxiliary pressure chamber is removed, which improves operating efficiency, and many other effects can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing one embodiment of the invention, FIG. 2 is a side view of a piston, and FIG. 3 is a side sectional view showing another embodiment of the invention. 1: Master cylinder, 2: Cylinder body, 3:
Small diameter hole in cylinder body, 4: Large diameter hole in cylinder body, 5: Piston, 6: Small diameter part of piston, 7:
Large diameter part of piston, 12: Groove, 13: Passing groove, 1
6: Main pressure chamber, 17: Auxiliary pressure chamber, 19: Valve body,
20: Valve member, 21, 22: Through hole of valve member, 2
5: Valve spring, 26: Return spring, 27:
Shaft-shaped member, 28: small hole, 30: valve device.

Claims (1)

[Claims] 1 The cylinder body 2 is slidably inserted into a small diameter hole 3 and a large diameter hole 4 that are connected to each other to form a main pressure chamber 16 on the small diameter hole 3 side and an auxiliary pressure chamber 17 on the large diameter hole 4 side. , a piston 5 having a small diameter portion 6 and a large diameter portion 7 having sliding surfaces that are in close contact with the small diameter hole 3; a return spring 26 that urges the piston 5 to the return position; established,
A valve device that can prevent the movement of fluid from the main pressure chamber 16 to the auxiliary pressure chamber 17 is provided between the auxiliary pressure chamber 17 and the reservoir, and is opened only when the pressure in the auxiliary pressure chamber 17 exceeds a predetermined pressure. It has a valve device 30 provided in the large diameter hole 4 for valving, and a small hole 28 that communicates the small diameter hole 3 with the reservoir. In the master cylinder 1, which allows the flow to flow into the
The valve device provided in the small diameter portion 6 of the piston 5 has a valve member 20 having a valve body 19 biased toward the auxiliary pressure chamber 17 and slidably inserted into the small diameter portion 6. A member 27 protruding into the auxiliary pressure chamber 17 can be brought into contact with the member 27, and the small diameter portion 6 is further provided with a
A groove 12 is provided which communicates with the small hole 28 when the piston 5 is in the return position, and a communication groove 13 is provided which communicates with the groove 12 and the auxiliary pressure chamber 17.
After the small diameter portion 6 moves forward and passes through the small hole 28, the auxiliary pressure chamber 17 and the reservoir communicate with each other via the small hole 28.