JPH0152223B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a valve mechanism control device for a brake booster, and more particularly to a valve mechanism control device that can improve brake feeling by reducing an invalid stroke during brake operation.

A brake booster controls the opening and closing of a valve mechanism via an operating lever that is linked to the brake pedal.
When the brake is operated, atmospheric pressure is introduced into the variable pressure chamber, and the pressure difference between the variable pressure chamber and the negative pressure chamber is applied to the power piston to obtain a boost function, and when the brake is released, communication between the variable pressure chamber and the atmosphere is cut off. At the same time, the variable pressure chamber is communicated with the negative pressure chamber, and a return spring returns the power piston to the non-operating position. In order to improve the responsiveness of the brake booster, it is preferable to increase the flow area between the upper variable pressure chamber and the atmosphere and between the variable pressure chamber and the negative pressure chamber, that is, to increase the lift amount of the valve mechanism. When the lift amount of the valve mechanism is increased in order to increase the flow path area between the variable pressure chamber and the negative pressure chamber, when the brake pedal is depressed from the non-operating state, the communication between the variable pressure chamber and the negative pressure chamber is established by the valve mechanism. This has the disadvantage that the amount of invalid stroke of the brake pedal required before the brake is shut off increases, resulting in poor brake feeling.

In order to improve such drawbacks, conventionally, a stopper member is provided on the operating lever, and when the brake operation is released and the power piston is returning to its original non-operating position, the large lift amount is used. A large flow path area is ensured, and when the power piston is in the non-operating position, the stopper member of the operating lever is brought into contact with a stopper provided on the closed shell to restrict free retreat of the operating lever; A valve mechanism control device is known in which the operating rod is moved forward relative to the power piston in the non-operating state so that the lift amount can be kept small.

However, in such a configuration, it is necessary to provide a stopper member on the operating rod at a position that protrudes from the power piston, and also to provide a stopper that comes into contact with the stopper member on the outside of the sealed shell, which makes it difficult to use the brake booster. The result was an increase in size, going against the trend toward lighter weight and smaller size in recent years.

The present invention has been made to eliminate these drawbacks, and it is possible to reduce the amount of valve lift without damaging the brake feeling by providing a stopper member in the sealed shell, without causing the risk of increasing the size of the device. It is an object of the present invention to provide a valve mechanism control device that can increase the number of brake pedals and reduce the invalid stroke amount of the brake pedal to substantially zero by finely adjusting the valve gap in the non-operating position.

In order to achieve the above object, the present invention provides a brake booster that controls fluid pressure applied to a power piston by controlling a valve mechanism forward and backward using an operating lever that is linked to a brake pedal. To the valve plunger connected to the tip,
A stopper member that comes into contact with the inner surface of the sealed shell body to restrict the retreating position of the valve plunger when the brake booster is not in operation is fixed, and the stopper member is provided with axial play within the radial hole of the power piston. The shell body is provided with an adjustment member that can move forward and backward to adjust the retreating position of either the stopper member or the power piston by coming into contact with either the stopper member or the power piston. It is characterized by what it did.

The present invention will be described below with reference to the illustrated embodiments.
In Fig. 1, 1 is a sealed shell body in which a front shell body 2 and a rear shell body 3 are brought into contact with each other, and a diaphragm 4 is clamped and supported between them; A power piston is fixed to the inner peripheral edge of the diaphragm 4, and the piston and the diaphragm 4 partition the inside of the shell 1 into a negative pressure chamber 6 and a variable pressure chamber 7, and the rear cylindrical portion 8 of this piston is connected to the rear shell. It is slidably projected from the opening of 3 through a seal 9. 10 is a return spring stretched between the front surface of the piston and the end wall of the front chamber 6 to press the piston 5 against the rear shell 3; 12 is a fitting hole provided at the center of the front surface of the piston 5; 13; is a driven rod in which the proximal end fitting part 14 is slidably fitted into this fitting hole, and the tip part passes through the end wall of the negative pressure chamber 6 airtightly via the seal 15 and connects to a master (not shown). The output is transmitted to the cylinder. 16
17 is a negative pressure rod connected to a negative pressure source such as an engine intake pipe opened in the end wall of the negative pressure chamber 6; 17 is the piston 5;
a communication path penetrating the inside of the tube and opening into the inside of the cylindrical part 8;
Reference numeral 18 designates another communication passage provided to communicate the internal chamber 19 of the piston 5 that communicates with the fitting hole 12 and the variable pressure chamber 7 .

The operating rod 20 is inserted through the air cleaner 21 from the rear opening of the cylindrical portion 8, and the spherical tip 22 has a valve plunger 23 slidably fitted into the internal chamber 19 of the piston 5. The end is caulked, and the rear end is linked to a brake pedal (not shown). Reference numeral 24 denotes a valve member that surrounds the operating rod 20 and is provided behind the spherical portion 22, and has a configuration in which a cylindrical plate member is covered with an elastic member such as rubber. It is fixed at the middle inner circumferential position. 26 is the above operation lever 2
a valve return spring provided between the receiving portion 28 attached to the intermediate flange portion 27 of 0 and the enlarged portion 25 of the valve member 24;
29 is a valve biasing spring provided between the front edge of the receiving portion 28 and the rear step portion of the valve member 24; 30 is provided on the rear surface of the driven rod fitting portion 14 inside the fitting hole 12;
A reaction disk made of rubber or the like is fitted with a gap between it and the valve plunger 23, and this disk seals off the internal chamber 19 from the negative pressure chamber 6.

Further, reference numeral 40 denotes a flat plate-shaped stopper member which is loosely inserted into the through hole 32 formed in the diametrical direction of the piston 5 so as to be movable in the axial direction.
The plunger 23 is mounted in the U-shaped groove so as not to be displaceable in the axial direction, and both ends of the stopper member 40 protrude from the through hole 32, respectively.

In the non-operating state of the brake booster, the stopper member 40, valve plunger 23, and contact rod 20 are stopped at the position where the stopper member 40 is in elastic contact with the rear shell 3 by the valve return spring 26, while the piston 5 is returned. The rear shell body 3 is biased by the spring 10.
It comes into contact with a support member 41 screwed through a seal member 43 at an appropriate position and is stopped. In this state, the stopper member 40 is located at an intermediate position of the through hole 32, and a gap l' is formed in front of the stopper member 40, and a gap l is formed in the rear thereof. In this state, the valve member 24 is brought into elastic contact with the valve seat 34 formed at the rear end of the valve plunger 23 by the valve biasing spring 29, so that the atmosphere side of the shaft portion of the valve member 24 and the internal chamber 19 on the outer periphery of the valve plunger 25 are connected. Further, the valve member 24 is formed on the power piston 5 and is in elastic contact with the valve seat 35 or is opposed to the valve seat 35 with a slight gap therebetween. Therefore, according to the above configuration, it is clear that by adjusting the protruding position of the support member 41 by loosening the fixing nut 42, the stop position of the piston 5, that is, the gap 1 can be adjusted, and the valve gap can be adjusted. be.

When the brake pedal is depressed from such a non-operating state and the operating rod 20 is moved forward against the valve return spring 26, the valve member 24 is completely brought into elastic contact with the valve seat 35, and the communication passage 17 and the internal chamber are brought into contact with each other. 19, that is, negative pressure chamber 6
The communication between the valve member 2 and the variable pressure chamber 7 is cut off.
4, the valve seat 34 of the valve plunger 23 is separated from the leading edge, and air enters the variable pressure chamber 7 via the internal chamber 19 and other communication passage 18, so the piston 5 moves forward against the return spring 10. , driven rod 13
operates the master cylinder and supplies brake fluid pressure to the brake cylinder. The maximum lift amount of the valve mechanism at this time is obtained by the gap l' between the stopper part 40 and the stepped part of the power piston 5.

When the pedal force is removed from the brake pedal, the valve plunger 23 is moved to the right together with the operating rod 20 by the valve return spring 26 relative to the piston 5, and the stopper member 40 is brought into step contact with the rear end surface thereof within the through hole 32. Ru. As a result, the valve plunger 2
The valve seat 34 of No. 3 contacts the valve member 24 to cut off communication between the variable pressure chamber 7 and the atmosphere, and at the same time, the valve member 24 is separated from the valve seat 35 to allow communication between the negative pressure chamber 6 and the variable pressure chamber 7. , and the gap between the valve member 24 and the valve seat 35 is the same as the amount l of movement of the stopper member 40 within the through hole 32 to the rear end surface with respect to the non-operating state of the brake booster described above. Expand only the amount. As a result, the variable pressure chamber 7 communicates with the negative pressure chamber 6 through a large flow path, and the pressure in the variable pressure chamber 7 quickly becomes the same as that in the negative pressure chamber 6, so the piston 5 returns. spring 10
This allows it to quickly return to its original non-operating position.

From this state, the power piston 5 is displaced to the right by the return spring 10, and the stopper member 40 is first brought into elastic contact with the rear shell 3 to stop the valve plunger 23 from retreating. On the other hand, the power piston 5 is further retreated until its back surface contacts the support member 41 and then stops, so the valve member 24
The distance between the valve seat 35 and the valve seat 35 is narrowed by the above l. In this state, as described above, the valve member 24
is seated on the valve seat 35, and is seated on the valve seat 35 with a small gap.
5, when the brake pedal is stepped on to activate the brake booster again, the fluid circuit is immediately switched by the valve mechanism. Therefore, when the piston 5 retreats, the valve member 24
Even if a large lift amount is secured between the valve seat 35 and the valve seat 35, it is possible to obtain a good brake feeling.

FIG. 2 shows an embodiment of the adjustment means for adjusting the amount of the gap 1, in which a bolt 41 as a support member is screwed into a predetermined position of the rear shell 3, and the tip of the bolt 41 is connected to the above-mentioned The stopper member 40 is brought into elastic contact. However, in this configuration, the support member 41 is opposed to the stopper member 40, and therefore the amount of protrusion of the support member 41 is limited relative to the piston 5, which is elastically supported by the rib 4a of the diaphragm 4 on the rear shell 3. Since the stopping position of the stopper member 40 can be adjusted by adjusting the gap l, the position of the valve member 24 with respect to the valve seat 35 is finely adjusted to adjust the invalid stroke of the brake pedal to substantially zero. This makes it easier.

As described above, according to the present invention, it is possible not only to increase the flow path area of pressure fluid while maintaining the amount of depression of the brake pedal in an optimal state, but also to house the stopper member for achieving this in the sealed shell. This makes it possible to achieve lighter weight and smaller size compared to the conventional device which required a stopper to be provided outside the sealed shell.Furthermore, by finely adjusting the valve gap in the non-operating position, the ineffective stroke of the brake pedal can be reduced. The effect is that it can be substantially eliminated.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention, and FIG. 2 is a longitudinal sectional view showing another embodiment. DESCRIPTION OF SYMBOLS 1... Sealed shell body, 2... Front shell body, 3... Rear shell body, 4... Diaphragm, 5... Power piston, 20... Operating rod, 23... Valve plunger, 2
4... Valve member, 31... Stopper member, 32...
Through hole, 34, 35... Valve seat, 41... Bolt,
l, l'... Gap.

Claims (1)

[Claims] 1. In a brake booster that controls the fluid pressure applied to a power piston by controlling a valve mechanism forward and backward using an operating lever linked to a brake pedal, a brake booster is installed on a valve plunger that constitutes the valve mechanism and is connected to the tip of the operating lever. A stopper member that comes into contact with the inner surface of the sealed shell body to restrict the retreating position of the valve plunger when the power device is not in operation is fixed, and the stopper member is inserted into the radial hole of the power piston with axial play. The shell body is provided with an adjustment member that can move forward and backward to adjust the retreating position of either the stopper member or the power piston by coming into contact with either the stopper member or the power piston. A valve mechanism control device for a brake booster, characterized by: