JPH054577Y2 - - Google Patents

Description

[Detailed Description of the Invention] a. Industrial Application Field The present invention relates to an oil supply device for a clutch booster, and in particular, a slave piston disposed between a power piston and an output rod is divided into two parts, and a first and a second slave piston, and these two
In a clutch booster that allows the output rod to retreat due to wear of the clutch plate by changing the volume of the hydraulic chamber formed between the two slave pistons, the oil supply system connected to the hydraulic chamber has a predetermined size. The present invention relates to an oil supply device equipped with a preload means for applying a preload.

b. Prior Art In medium and large vehicles such as trucks and buses,
A clutch booster is installed to facilitate clutch operation. This clutch booster is composed of a power cylinder section 1 and a slave cylinder section 2 as shown in Fig. 3, for example, and the forward force of a power piston 3 of the power cylinder section 1 acts on a clutch lever (not shown) through a first slave piston 4, a second slave piston 5 and an output rod 6.

Specifically, when the clutch pedal 7 is depressed, the control device 8 detects the amount of depression, and the control valve 9 is controlled according to the detection result, and compressed air corresponding to the amount of depression is delivered from the air reservoir 10 to the power cylinder section 1. It is supplied to the pressure chamber 11.

When compressed air is supplied to the pressure chamber 11, the power piston 3 moves forward in the direction of arrow a in FIG. At this time, the valve body 13 attached to the tip of the piston rod 12 closes the valve seat 14, so a sealed hydraulic chamber 15 is formed between the first slave piston 4 and the second slave piston 5. do.
Therefore, the forward force of the piston rod 12 is transmitted from the first slave piston 4 to the second slave piston 5 via the hydraulic chamber 15, and is further transmitted to the output rod 6.
is transmitted to the clutch lever via.

On the other hand, when the clutch pedal 7 is released, the pressure chamber 1
1 of compressed air is discharged to the outside from the control valve 9, and the power piston 3 moves back in the direction of arrow b in FIG. 3 due to the biasing force of the return spring 16. When the power piston 3 moves back, the valve seat 14 is opened, and the hydraulic chamber 15 is communicated with the oil reservoir 21 through the passage 17 of the first slave piston 4, the oil chamber 18, the oil port 19, and the pipe 20.
Therefore, even if the clutch plate wears out in this state, the output rod 6 can be moved back in the direction of the arrow c in FIG. 3, so that the clutch pedal 7 can be prevented from shifting its engagement/disengagement position.

c. Problems to be Solved by the Invention Although the conventional clutch booster is constructed, for example, as described above, the following problems have been pointed out with this clutch booster. That is, as the power piston 3 moves forward, the volume of the oil chamber 18 increases, and as a result, the oil in the oil reservoir 21 is sucked into the oil chamber 18 from the oil port 19.
When the stroke of the power piston 3 is relatively fast, the pressure in the oil chamber 18 is significantly reduced and small bubbles are generated in the oil. When air bubbles are generated in this way, a part of them passes through the passage 17 and enters the hydraulic chamber 15.
Even if the hydraulic chamber 15 is sealed, the distance between the first and second slave pistons 4 and 5 becomes unstable due to the change in the volume of the bubbles, causing the clutch pedal 7 to be in the disconnected position. A misalignment will occur.

The present invention was devised to effectively solve the above-mentioned problems, and its purpose is to create an oil supply device for a clutch booster that does not generate bubbles in the oil even when the stroke of the power piston is fast. It is about providing.

d. Means for Solving the Problems In order to solve the above-mentioned problems, the present invention includes a first slave piston and a second slave piston each disposed in a slave cylinder section adjacent to a power cylinder section with a hydraulic chamber in between. , the first slave piston is connected to a power piston via a piston rod, the second slave piston is connected to a clutch lever via an output rod, and the hydraulic chamber is connected to an oil reservoir via an on-off valve. In the clutch booster, the on-off valve is configured to be closed and opened by the reciprocating movement of the power piston, and an oil chamber is connected to the slave cylinder section by removing it from the forward power transmission system of the power piston. The oil supply system leading to the on-off valve is provided with pre-pressure means for always applying a pre-pressure of a predetermined magnitude to the oil fluid supplied from the oil reservoir to the oil fluid chamber.

e. Effect In the clutch booster oil supply device configured as described above, when the power piston moves forward, oil from the oil reservoir is sucked into the slave cylinder portion of the clutch booster, but the oil is pre-pressurized by the pre-pressure means. Therefore, even if the power piston rapidly moves forward, the oil pressure does not drop significantly, and it is therefore possible to prevent air bubbles from forming in the oil.

f. Example An example of the present invention will be described below based on FIGS. 1 and 2. FIG. 1 shows a first embodiment of the present invention, in which a diaphragm 25 disposed above the oil level in an oil reservoir 24 is moved by a preload spring 26 as a preload means. It is designed to always be energized downward. In the figure, 27 is a spring receiver, and 28 is a ventilation hole.

In the oil supply device configured as described above, the oil is preloaded by the preload spring 26, and this preloaded oil is supplied to the clutch booster, so that the power piston 3 shown in FIG. 3 rapidly moves forward. Even if the power piston 3 is in the forward power transmission system, the pressure in the oil chamber 18 outside the forward power transmission system can be prevented from decreasing significantly, and the generation of air bubbles in the oil can be prevented.

Furthermore, various configurations other than the preload spring 26 described above can be adopted as the preload means, and for example, a preload device 31 may be disposed in the middle of the piping 20 as shown in FIG. 2. This preload device 31 has a piston 33 disposed within a cylinder 32, and the piston 33 is biased by a preload spring 34. For details, connect one end of the cylinder 32 to the pipe 2
It is connected to a conventional oil reservoir 35 by 0a, and the other end is connected to the oil port 19 of the clutch booster shown in FIG. 3 by a pipe 20b. Also, a valve seat hole 36 is located in the center of the piston 33.
The valve seat hole 36 is normally closed by a ball valve 38 biased by a spring 37. On the other hand, one end of the preload spring 34 is supported by a spring receiver 39 that abuts the end of the cylinder 32, and a valve opening rod 40 is protruded from the center of the spring receiver 39. Note that the preload device 31 can also be integrated with the clutch booster.

In the preload device configured as shown in FIG. 2, the oil is preloaded by the preload spring 34, and this preloaded oil is supplied to the clutch booster through the pipe 20b, thereby preventing the generation of air bubbles in the oil. In addition, if the amount of oil returned to the preload device 31 when the power piston 3 moves backward is too large,
Since the valve opening rod 40 pushes open the ball valve 38,
Excess oil is returned to the oil reservoir 35 through the pipe 20a.

Furthermore, since the oil is pre-pressurized as mentioned above,
As shown in FIG. 3, even if the constant contact spring 22 of the clutch disposed between the first and second slave pistons 4 and 5 is omitted, the second slave piston 5 can be biased in the operating direction. The structure can also be simplified by omitting the spring 22.

g. Effects of the invention As mentioned above, in this invention, the oil supplied to the clutch booster is pre-pressurized by the pre-pressure means, so even if the power piston moves rapidly forward, the oil pressure will not drop significantly. Therefore, it is possible to prevent air bubbles from forming in the oil, and prevent air bubbles from entering the hydraulic chamber between the first and second slave pistons and causing the clutch pedal to displace. It is possible to reliably prevent such problems.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of an oil reservoir showing a first embodiment of the present invention, and FIG. 2 is a longitudinal cross-sectional view of a preload device and an oil reservoir showing a second embodiment of the present invention. FIG. 3 is a longitudinal sectional view of a conventional clutch booster. DESCRIPTION OF SYMBOLS 1... Power cylinder part, 2... Slave cylinder part, 3... Power piston, 4... First slave piston, 5... Second slave piston, 6... Output rod, 12... Piston rod, 13 ... Valve body, 14 ... Valve seat, 15 ... Hydraulic chamber, 18 ... Oil chamber, 19 ... Oil port, 2
0... Piping, 21, 24, 35... Oil reservoir, 25... Diaphragm, 26, 34... Preload spring, 31... Preload device, 33... Piston, 3
8...Ball valve, 40...Valve opening rod.

Claims (1)

[Scope of utility model registration request] First and second slave pistons are respectively disposed in a slave cylinder section adjacent to the power cylinder section with a hydraulic chamber in between, and the first slave piston is connected to the power piston via a piston rod, and the first slave piston is connected to the power piston via a piston rod. A second slave piston is connected to the clutch lever via an output rod, and the hydraulic chamber is communicated with an oil reservoir via an on-off valve, and the on-off valve is closed and opened by the forward and backward movements of the power piston. In the clutch booster configured as above, an oil chamber is formed in the slave cylinder section separated from the forward power transmission system of the power piston, and an oil chamber is connected from the oil reservoir to the oil supply system leading from the oil reservoir to the on-off valve. 1. An oil supply device for a clutch booster, characterized in that a preload means is provided for always applying a predetermined amount of prepressure to the oil supplied to the oil chamber.