JPH0143664B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a brake booster, and more particularly to a brake booster in which a master cylinder is disposed on the rear side of a booster mechanism including a power piston, that is, on the brake pedal side.

In conventional brake boosters commonly used, a master cylinder is connected to the front side of the booster mechanism, and the shell of the booster mechanism is attached to the vehicle body. A brake booster with such a configuration is
It is widely used because the valve mechanism that controls the opening and closing of the pressure fluid flow path according to the forward and backward movement of the input shaft and the structure of the flow path are relatively simple, but it is only necessary to support the master cylinder on the shell. Because of the required rigidity, there was a certain limit to the weight reduction of the brake booster by reducing the thickness of the shell.

On the other hand, in a brake booster in which the master cylinder is placed on the rear side of the booster mechanism, the master cylinder can be attached to the vehicle body, so the shell simply has enough rigidity to withstand fluid pressure. This is advantageous in reducing the weight of the brake booster. However, since the positions of the booster mechanism and the master cylinder are reversed, if the simple valve mechanism used in general brake boosters is used as is, the operating direction of the input shaft must be reversed. In order to avoid this, a valve mechanism with a complicated structure has conventionally been used.

In view of the above-mentioned points, the present invention provides a brake booster in which a master cylinder is arranged on the rear side of the booster mechanism, as well as a brake booster having two valve seats for one valve body, as in a general brake booster. This allows the use of a two-seat type valve mechanism, which simplifies and reduces the weight of the valve mechanism parts, making it possible to further reduce the overall weight of the brake booster. It is.

That is, the present invention includes a power piston slidably provided in a shell, a valve mechanism housed in a valve body of the power piston shaft, a constant pressure chamber formed on the front side in the operating direction of the power piston, and a constant pressure chamber formed on the rear side in the operating direction of the power piston. A variable pressure chamber is formed, a master cylinder is connected to the rear shell on the side of the variable pressure chamber, an input shaft is passed through the master cylinder and linked to the valve mechanism, and pressure fluid is supplied to the valve mechanism from the front side of the power piston. and an output shaft that interlocks the power piston and the piston of the master cylinder, the valve mechanism includes a first valve seat formed on the valve body, and a second valve formed on the input shaft. a seat, and a valve body seated on a first valve seat and a second valve seat from the front side of the power piston, and the outside of the seat portion between the valve body and a first valve seat formed on the valve body is In the supply passage, the inner side of the seat between the valve body and the second valve seat provided on the input shaft and arranged inside the first valve seat is a constant pressure chamber, and the intermediate between both seat parts is the variable pressure chamber. The present invention provides a brake booster characterized in that the brake booster is connected to the brake booster and the brake booster.

The present invention will be described below with reference to the illustrated embodiments.
In FIG. 1, 1 is a shell consisting of a front shell 1a and a rear shell 1b.
Connect the tip of the master cylinder 2 to the shaft of the
The base of this master cylinder 2 is fixed to the vehicle body 3. A valve body 5 integrally equipped with a power piston 4 is provided inside the shell 1 so as to be able to reciprocate along the axial direction of the shell 1. The front shell 1
It is divided into a constant pressure chamber 7 on the a side and a variable pressure chamber 8 on the rear shell 1b side.

The valve body 5 is generally formed into a cylindrical shape as a whole, and its tip can protrude to the outside through an opening 9 formed in the shaft of the front shell 1a while being kept airtight by the base 10a of the seat member 10. ing. Then, by folding the tip end 10b of the seal member 10 from the intermediate portion to the inside of the base portion 10a and connecting it to the tip portion of the valve body 5, the seal member 10 can be used as a dust cover for the sliding portion between the valve body 5 and the base portion 10a. We are using. Further, the valve body 5 is normally held in the non-operating position shown in the figure, in which it abuts against the housing 12 of the master cylinder 2, by a return spring 11 mounted between the valve body 5 and the front shell 1a.

A valve mechanism 15 for switching the fluid circuit is provided inside the valve body 5, and this valve mechanism 15 is connected to an annular first valve seat 1 formed on the inner peripheral surface of the valve body 5.
6, a second valve seat 18 formed at the tip of the input shaft 17 inside the first valve seat 16, and further seated on each valve seat 16, 18 from the front side in the operating direction of the power piston 4, that is, from the left side in FIG. A valve body 19 is provided. In the illustrated non-operating state, the valve body 19 is seated on the first valve seat 16 by a spring 21 elastically loaded between the valve body 19 and a closing member 20 that closes the shaft hole of the valve body 5. The second valve seat 18 of the input shaft 17 is separated from the valve body 19 seated on the first valve seat 16 by a spring 22 that is elastically loaded between the closing member 20 and the input shaft 17.

The valve body 19 has a cylindrical seal portion 19 on its inner circumference.
a, and by connecting this cylindrical seal portion 19a to the closing member 20, the cylindrical seal portion 19
A plurality of axial passages 23 that form a space by the outer periphery of a, the closing member 20 and the seal portion between the valve body 19 and the first valve seat 16, and the space is formed in the closing member 20, and the closing member 20 and seal member 1
It is communicated with the atmosphere through a filter 24 provided between the tip end 10b of the 0 and the tip 10b. On the other hand, the inner circumference of the cylindrical seal portion 19a, the closing member 20, and the input shaft 1
7, and the second valve seat 18 and valve body 19 of the input shaft 17
The space formed by the sealing portion of the closing member 20 includes a plurality of radial passages 25 formed in the closing member 20 so as not to communicate with the axial passage 23 of the closing member 20 and a passage 26 formed in the valve body 5.
It communicates with the constant pressure chamber 7 via. Furthermore, the space between the sealing part between the valve body 19 and the first valve seat 16 and the sealing part between the valve body 19 and the second valve seat 18 is
The valve body 5 communicates with the variable pressure chamber 8 via an axial passage 27 formed in the valve body 5 .

The input shaft 17 consists of a first input shaft 17a and a second input shaft 17b, and the second valve seat 18 is formed at the tip of the first input shaft 17a. This first input shaft 17a is slidably passed through the shaft portion of the housing 12 of the master cylinder 2, and a second input shaft 17b is connected to the end portion of the first input shaft 17a via a connecting member 30.
This second input shaft 1
The distal end of 7b is linked to a brake pedal (not shown). An output shaft 32 for transmitting the thrust of the power piston 4 to the piston 31 of the master cylinder 2 is slidably fitted on the outer periphery of the first input shaft 17a, and in this embodiment, the output shaft 32 and the piston 31 is constructed from an integrated stepped hollow tube.

The tip of the output shaft 32 extends to the vicinity of the second valve seat 18 of the input shaft 17, and a reaction disk 34 is disposed on the back side of a nut member 33 screwed onto the tip.
The thrust force applied to the shaft can be received through the reaction disk 34 and the nut member 33. Further, a cylindrical connecting member 35 is screwed onto the outer periphery of the second valve seat 18 of the input shaft 17, and the nut member 35 and the reaction disk 34 are slidably housed within the cylindrical connecting member 35. At the same time, the base of the connecting member 35 is curved inward and positioned on the back side of the reaction disk 34, so that the reaction force from the reaction disk 34 can be transmitted to the brake pedal via the connecting member 35 and the input shaft 17. That's what I do.

The output shaft 32 slidably passes through the shaft portion of the housing 12 of the master cylinder 2 and a pair of seal members 40 and 41 provided on the sleeve 13 to maintain liquid tightness. In the illustrated embodiment, the master cylinder 2 is configured as a two-system master cylinder, with the piston 31 integrated with the output shaft 32 serving as the primary piston. The secondary piston 42 is slidably fitted between the output shaft 32 and the sleeve 13 while maintaining fluid tightness, and normally a spring 43 loaded between both pistons 31 and 42 causes the piston 42 to be connected to the output shaft. Stopper ring 44 provided at 32
I'm trying to make it come into contact with.

The above-mentioned two-system master cylinder 2 can be constructed in the same manner as the conventional two-system master cylinder 2, except that the pistons 31 and 42 have a special structure. is omitted. In addition, in FIG. 1, 45 is the pressure chamber of one system, 46 is the pressure chamber of the other system,
47 is a reservoir.

In the above configuration, in the non-operating state shown in the figure, the power piston 4 and the valve body 5 are in contact with the housing 12 of the master cylinder 2 by the return spring 11, and the input shaft 17 is urged rightward together with the output shaft 32 by the spring 22. is,
The reaction disk 34 is stopped in a slightly compressed state with respect to the valve body 5 which is stopped in contact with the housing 12. In this state, the valve body 19 is seated on the first valve seat 16 to cut off communication between the variable pressure chamber 8 and the atmosphere, and the valve body 19 and the second valve seat 18 are separated from each other to form the variable pressure chamber 8 and the constant pressure chamber. It connects 7 spaces. Therefore, the negative pressure introduced into the constant pressure chamber 7 from the negative pressure inlet (not shown) provided in the front shell 1a is transmitted through the passages 26, 25, the gap between the valve body 19 and the second valve seat 18, and the passage 27. The power piston 4 is introduced into the variable pressure chamber 8 through the power piston 4, and there is no pressure difference between the front and rear of the power piston 4.

When the brake pedal (not shown) is depressed from this state and the input shaft 17 is moved to the left, the second valve seat 18 first seats on the valve body 19 to cut off communication between the constant pressure chamber 7 and variable pressure chamber 8. As the input shaft 17 continues to move to the left, the valve body 19 is removed from the first valve seat 16. Then, the atmosphere is introduced into the variable pressure chamber 8 through the filter 24, the passage 23, the gap between the valve body 19 and the first valve seat 16, and the passage 27, and the power piston 4
In addition, a pressure difference is generated before and after the valve body 5, and the valve body 5 is moved to the left against the return spring 11.

When the valve body 5 moves to the left, its thrust is transmitted to the primary side piston 31 of the master cylinder 2 via the reaction disk 34, nut member 33 and output shaft 32, and this piston 31 moves to the left to open the pressure chamber 45. When brake fluid pressure is generated within the pressure chamber 46, the secondary piston 42 is moved to the left and brake fluid pressure is generated within the pressure chamber 46. The brake fluid pressure generated in each pressure chamber 45, 46 is supplied to a wheel cylinder (not shown) to perform a braking operation, as is conventionally known. During this time, as described above, the brake reaction force is transmitted from the reaction disk 34 to the brake pedal via the connecting member 35 and the input shaft 17.

It is clear that when the depression force on the brake pedal is released from the braking state, the valve mechanism 15 switches to the state shown in the figure, and therefore returns to the non-operating state described above. At this time, since the valve body 5 is biased to the right by atmospheric pressure, the return spring 11 can be a lightweight one with weaker elasticity than conventional ones, or the return spring 11 can be 11 can be omitted, the weight of the brake booster can be reduced accordingly.

FIG. 2 shows another embodiment of the present invention,
The main difference from the above-mentioned embodiment is the reaction force mechanism,
In this embodiment, the generated brake fluid pressure is transmitted to the brake pedal as a reaction force.

In this embodiment, a roughly cup-shaped valve body 105 is disposed on the front side of the shaft of the power piston 104, and a cylindrical bolt 15 is screwed into the tip step of the output shaft 132 and the shaft of the output shaft 132.
By sandwiching the valve body 105 and the power piston 104 with the head of the valve 0, the valve body 105 and the power piston 104 are integrally connected to each other. The first input shaft 117a constituting the input shaft 117 is connected to the cylindrical bolt 150.
A valve mechanism 115 is installed at the tip of the valve mechanism 115.
A second valve seat 118 is provided. The output shaft 132 and the cylindrical bolt 150 integrated therewith
A reaction force transmitting member 151 is slidably fitted between the inner surface of the first input shaft 117a and the outer surface of the first input shaft 117a while maintaining liquid tightness, and the space in front of the reaction force transmitting member 151 is defined as a reaction force chamber. The pressure chamber 146 in the master cylinder 102 is communicated with the pressure chamber 152 . Further, the reaction force transmitting member 151 is normally brought into contact with the cylindrical bolt 150 by a spring 154 elastically loaded between this and a retainer 153 attached to the output shaft 132, and in this state, the reaction force transmitting member 151 is placed on the base side of the first input shaft 117a. A required gap δ is formed between the large diameter portion and the end face of the large diameter portion.

The rest of the structure is substantially the same as that of the embodiment described above, and the main parts that are the same as or corresponding to those of the embodiment described above are designated by the same reference numerals as in FIG.
It is shown with a code incremented by 100. Note that the return spring is omitted in this embodiment.

In the above configuration, when the brake pedal is depressed and the input shaft 117 is moved to the left, the valve mechanism 115 is switched and the pressure change chamber 10 is
Atmospheric air is introduced into the chamber 8, which causes the power piston 104, valve body 105, output shaft 132, and piston 131 to move to the left, and brake fluid pressure is generated in the pressure chamber 145, which causes the piston 142 to move to the left. As a result, brake fluid pressure is also generated within the pressure chamber 146 and this pressure is introduced into the reaction force chamber 152.

At the beginning of braking when the brake fluid pressure introduced into the reaction force chamber 152 is low, the reaction force transmission member 151 is held in contact with the cylindrical bolt 150 by the spring 154, and in this state, the reaction force transmission member 151 is held in contact with the cylindrical bolt 150. Part 1
A gap δ is maintained between the input shaft 51 and the end surface of the large diameter portion of the first input shaft 117a, so that brake fluid pressure is not transmitted to the input shaft 117 as a reaction force. When the brake fluid pressure in the reaction force chamber 152 rises and the reaction force transmission member 151 is brought into contact with the end surface of the large diameter portion of the first input shaft 117a against the spring 154, the brake fluid pressure increases for the first time. is the input shaft 11 as a reaction force.
7 will be transmitted.

As is clear from the above explanation, the present invention provides a brake booster in which a master cylinder is arranged on the rear side of the booster mechanism, in which the valve mechanism is a one-valve, two-seat type valve mechanism with a simple configuration. Therefore, the advantage of weight reduction that this type of brake booster has can be further promoted.

[Brief explanation of drawings]

FIG. 1 is a half sectional view showing one embodiment of the invention, and FIG. 2 is a half sectional view showing another embodiment of the invention. 1,101...Ciel, 2,102...Master cylinder, 4,104...Power piston,
5,105... Valve body, 7,107... Constant pressure chamber, 8,108... Variable pressure chamber, 15,115...
Valve mechanism, 16, 116...first valve seat, 17, 11
7...Input shaft, 18,118...Second valve seat, 1
9,119... Valve body, 23, 25, 26, 27,
123, 125, 126, 127...Aisle, 3
1, 42, 131, 142... Piston, 32,
132...Output shaft.

Claims (1)

[Scope of Claims] 1. A power piston slidably provided in a shell, a valve mechanism housed in a valve body of the power piston shaft, a constant pressure chamber formed on the front side in the operating direction of the power piston, and a rearward portion of the power piston. A variable pressure chamber formed on the side, a master cylinder connected to the rear shell on the side of the variable pressure chamber, an input shaft that passes through the master cylinder and is linked to the valve mechanism, and a variable pressure chamber formed on the valve mechanism from the front side of the power piston. The valve mechanism includes a supply passage for supplying pressure fluid and an output shaft that interlocks the power piston and the piston of the master cylinder, and the valve mechanism includes a first valve seat formed on the valve body and a first valve seat formed on the input shaft. 2 valve seats, and a valve body seated on a first valve seat and a second valve seat from the front side of the power piston, and from a seat portion between the valve body and a first valve seat formed on the valve body. The outside is connected to the supply passage, the inside of the seat between the valve body and the second valve seat, which is provided on the input shaft and arranged inside the first valve seat, is connected to the constant pressure chamber, and the middle between both seats is connected to the above-mentioned valve seat. A brake booster characterized in that each of the brake boosters is connected to a variable pressure chamber.