JPH0539022Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a negative pressure booster used in a brake booster, etc., and particularly relates to a negative pressure booster equipped with a reaction disk. be.

(Prior Art) Conventionally, in a brake booster using negative pressure, the brake reaction force is transmitted to the brake pedal by a reaction force means in order to allow the driver to sense the magnitude of the braking force during operation. .

As one of such reaction force means,
2. Description of the Related Art A reaction disk made of an elastic member is known, as disclosed in Japanese Patent No. 70964 and the like.

This reaction disk is disposed in a recessed part formed at the front end of the valve body of the brake booster. The rear end of the output shaft is in contact with the front surface of this reaction disk, and the front end of a valve plunger connected to the input shaft is opposed to the rear surface of the reaction disk.

When the negative pressure booster operates and the output shaft operates the brake master cylinder, the reaction force is transmitted to the reaction disk via the output shaft. For this reason, the reaction disk deforms elastically according to the magnitude of the reaction force, and uses its elasticity to transmit the reaction force to the valve plunger, which in turn is connected to the brake pedal via an input shaft connected to it. It is designed to transmit reaction force. In this way, the driver can sense the magnitude of the braking force.

(Problem to be solved by the invention) By the way, in a negative pressure booster equipped with such a reaction disk, in order to transmit the reaction force from the output shaft to the valve plunger via the reaction disk, The recessed part in which the reaction disk is disposed has a structure in which it has no choice but to communicate with the valve plunger side.

However, with a structure in which the recessed fitting part communicates with the valve plunger side, when the brake booster is activated, the atmosphere enters the recessed fitting part from the valve plunger side and acts on the rear surface of the reaction disk. Become. In this way, when the atmosphere acts on the rear surface of the reaction disk, the negative pressure of the constant pressure chamber acts on the front surface of the reaction disk, so a pressure difference is created between the front and rear surfaces of the reaction disk. A forward force is applied to the reaction disk. However, at the very beginning of operation, braking force has not yet been generated and the braking reaction force is not transmitted to the reaction disk via the output shaft, so the reaction disk moves slightly forward due to this force. Put it away. For this reason, the rear surface of the reaction disk rises slightly from the bottom surface of the recessed fit, and the atmosphere flows through the minute gap between the rear surface of the reaction disk and the bottom of the recessed fit into a constant pressure chamber where negative pressure is maintained at all times. begins to invade. As a result, a problem arises in that the output of the negative pressure booster is lost.

In order to deal with this problem, the booster shown in the above-mentioned publication is provided with a spring means on the retainer to prevent the output shaft from coming off, and this spring means moves the reaction disk toward the valve plunger. I'm trying to press on. Therefore, by doing this, even if atmospheric pressure is applied to the rear surface of the reaction disk at the very beginning of braking, the reaction disk is prevented from moving forward due to the biasing force of the spring means.

However, if the spring means for preventing the output shaft from slipping out and the spring means for pressing the reaction disk were to be used together, the material of the retainer would have to be changed from a soft iron plate to spring steel, which would increase costs. Put it away. Moreover, since it requires molding, it cannot be manufactured easily.

Furthermore, the set load of the spring that presses the reaction disk tends to vary, making it extremely difficult to manage. As described above, when the set load of the spring varies, the jumping load required of the booster at the initial stage of operation also varies greatly, causing a problem that good jumping characteristics cannot be obtained.

The present invention was devised in view of these problems, and its purpose is to minimize the output loss at the initial stage of braking, and to easily and easily attach the retainer for preventing the output shaft from coming off. An object of the present invention is to provide a negative pressure booster that can be manufactured at low cost.

Another object of the present invention is to provide a negative pressure booster that can obtain good jumping characteristics by keeping the initial pressing force of the reaction disk substantially constant.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention is arranged so as to be movable in and out of the space formed by the front shell and the rear shell, and to airtightly seal the rear shell. a valve body which is slidably penetrated through the valve body; a constant pressure chamber which is connected to the valve body and into which negative pressure is introduced; and a variable pressure chamber into which negative pressure is introduced when not in operation and atmospheric pressure is introduced when in operation. a power piston divided into two parts; a valve plunger slidably disposed in an axial through hole formed in the valve body; and an input connected to the valve plunger and disposed movably in the valve body. a control valve provided within the valve body and operated by the valve plunger to selectively communicate the variable pressure chamber with the atmosphere or the constant pressure chamber; and the valve body facing the constant pressure chamber. an output shaft whose rear end part is fitted into a recessed fitting part formed at the front end part of the output shaft, and whose front end part penetrates the front shell and protrudes to the outside; and a recess formed at the rear end part of the output shaft. In the negative pressure booster, the negative pressure booster is further provided with a reaction disk disposed to face the axial through-hole inside the output shaft, and a recessed portion of the output shaft is connected to the outside of the output shaft. Along with drilling a communicating hole,
This hole is characterized in that an atmospheric passage is formed through which the atmospheric air is introduced to the side surface of the output shaft of the reaction disk.

(Function) In the negative pressure booster according to the present invention having such a configuration, atmospheric pressure always acts on the front surface of the reaction disk, that is, the side surface of the output shaft. Therefore, when the atmosphere is introduced into the variable pressure chamber at the beginning of braking, even if the atmosphere acts on the rear surface of the reaction disk, that is, the side surface of the valve plunger, the reaction disk will not be placed on the output shaft side. There is no pressure difference that would create a force that would cause it to move. Therefore, airtight leakage between the reaction disk and the valve body due to the reaction disk lifting up from the bottom of the recessed fitting portion of the valve body is reliably prevented.

Further, the conventional spring means for pressing the reaction disk is not required, and an inexpensive soft iron material can be used to prevent the output shaft from coming off.

Further, since a constant atmospheric pressure always acts on the reaction disk, the initial load pressing the reaction disk is approximately constant, so that the negative pressure booster has good jumping characteristics.

(Example) Hereinafter, an example of the present invention will be described using the drawings.

FIG. 1 is a longitudinal sectional view showing an embodiment in which a negative pressure booster according to the present invention is applied to a brake booster.

As shown in FIG. 1, the brake booster 1 includes a front shell 2 and a rear shell 3.
are connected, for example, by bayonet connection or the like.

A valve body 4 is disposed so as to pass through the rear shell 3, and the valve body 4 is supported by the rear shell 3 and the seal member 5 in an airtight and slidable manner. A power piston member 6 disposed in a space within both shells 2 and 3 is connected to the valve body 4. A diaphragm 7 is provided between the shells 2, 3 and the valve body 4 on the back side of the power piston member 6. A power piston 8 is constituted by the power piston member 6 and the diaphragm 7, and the space inside both shells 2 and 3 is transformed into a constant pressure chamber 9 by the power piston 8.
and a pressure-changing room 10.

A recessed fitting part 11 that opens into the constant pressure chamber 9 is formed in the valve body 4, and the bottom of this recessed fitting part 11 has a protruding part 4 whose central portion protrudes toward the constant pressure chamber 9 side.
a is formed. A first hole 12 that opens into the recessed fitting portion 11 is formed approximately at the center of the protruding portion 4a, and a second hole is formed in succession from the first hole 12 toward the rear (to the right in the figure). 13, a third hole 14, a fourth hole 15, a fifth hole 16, and a sixth hole 17 that opens to the atmosphere. That is, an axial through hole is formed in the center of the valve body 4 and extends from the front end surface to the rear end surface of the valve body 4 in the axial direction.

An axial passage 18 that communicates the negative pressure chamber 9 and the fifth hole 16 is bored in the valve body 4 .

Further, a front end portion of a valve plunger 19 is slidably fitted into the second hole 13 of the valve body 4, and a rear end portion of the valve plunger 19 is fitted into the third hole 14, respectively. An input shaft 20 that is connected to a brake pedal (not shown) is connected to the rear end of the valve plunger 19. Valve body 4 has
A radial hole 21 is formed perpendicular to the third hole 14, and a key member 22 is fitted into the valve plunger 19 through the hole 21 so as to be movable relative to the valve plunger 19 in the axial direction. ing. Further, the key member 22 can be moved in the axial direction together with the valve plunger 19 by the width of the hole 21 (ie, the axial length). Further, the key member 22 allows the valve plunger 19 to be connected to the valve body 4.
are prevented from escaping.

Further, a passage 23 opening into the variable pressure chamber 10 is bored in the valve body 4 so as to be perpendicular to the third hole 14 . This passage 23 communicates with the fourth hole 15 via a passage 14a formed in the third hole 14.

A control valve 24 is provided in the sixth hole 17 of the valve body 4.
is provided. The control valve 24 includes a valve body 26 that is attached to the valve body 4 and is constantly biased toward the valve plunger 19 by the elastic force of a spring 25 interposed between the valve body 4 and the input shaft 20, and a valve body 26 that is always biased toward the valve plunger 19. A first valve seat 27 formed at the rear end of 19
and a second valve seat 28 formed on the valve body 4. When the valve body 26 is seated on the first valve seat 27 and separated from the second valve seat 28, the control valve 24 communicates between the constant pressure chamber 9 and the variable pressure chamber 10, and connects the variable pressure chamber 10 with the atmosphere. When the valve body 26 is separated from the first valve seat 27 and is seated on the second valve seat 28, the constant pressure chamber 9
Switching control is performed to cut off the communication between the variable pressure chamber 10 and the variable pressure chamber 10, and to communicate the variable pressure chamber 10 with the atmosphere.

An output shaft 29 is provided in the recessed fitting portion 11 of the valve body 4.
A rear end large diameter portion 29a is provided, and a recess 29b formed in the rear end large diameter portion 29a is slidably fitted into the protrusion 4a of the valve body 4. A reaction disk 30 is housed in the recess 29b of the rear end large diameter portion 29a, and the reaction disk 30 is disposed opposite to the first hole 12 that constitutes the axial through hole of the valve body 4. There is. As shown in FIG. 2, the front surface of the reaction disk 30, that is, the side surface of the output shaft, is formed into a stepped shape with a central portion protruding toward the output shaft side. Further, a back plate 30a is fixed to the front surface of the central protrusion. Further, a lip-shaped projection 30b is provided on the circumferential surface of the central protrusion, and airtightness between the projection 30b and the output shaft is maintained.

Then, this back plate 30a and the output shaft 2
A hole 31 is bored in the output shaft 29 so as to communicate with the space between the output shaft 29 and the output shaft 9 . This hole 31
is provided at the tip of the output shaft 29 and communicates with a female threaded hole 34 into which a distance adjustment shaft 33 that presses the piston 32 of the master cylinder and adjusts the distance between the piston 32 and the output shaft 29 is screwed. There is. The tip of the output shaft 29 is kept airtight by a seal, passes through the shell 2, and protrudes to the outside, so that the inside of the female threaded hole 34 is always in communication with the atmosphere. Therefore, atmospheric pressure is constantly introduced through the hole 31 into the space facing the back plate 30a. That is, atmospheric pressure is always acting on the side surface of the output shaft of the reaction disk 30. Thus, the hole 31 and the female threaded hole 34 constitute the atmospheric passage of the present invention.

As shown in FIG. 2A, when the negative pressure booster is assembled, both the constant pressure chamber 9 and variable pressure chamber 10 are at atmospheric pressure, so the reaction disk 30 is hardly pressed against the valve body 4 side. . However, as shown in FIG. 2B, when negative pressure is introduced into the constant pressure chamber 9 and the variable pressure chamber 10, the reaction disk 30 is forced into the valve body 4 by the atmospheric pressure introduced through the hole 31. It becomes crimped. Therefore, airtightness between the reaction disk 30 and the valve body 4 is ensured. Furthermore, the lip-like protrusion 30b prevents atmospheric air from leaking into the constant pressure chamber 9 from the hole 31.

Since the compression force of the reaction disk 30 to the valve body 4 is only about 1 to 2 kg, the diameter d of the central protrusion is 1<(π/4)d ² P<2 Kg (P=atmospheric pressure). Just set it so that it is.

Furthermore, a spacing member 35 is interposed in the first hole 12 between the reaction disk 30 and the left end of the valve plunger 19 . By appropriately changing the cross-sectional area of this spacing member 35, the valve plunger 1
Even if the cross-sectional area of 9 is kept constant, the boost ratio can be changed. This makes it possible to use the valve plunger 19 in common for various negative pressure boosters.

A predetermined gap is set between the spacing member 35, the valve plunger 19, and the reaction disk 30.

The output shaft 29 is prevented from coming out of the valve body 4 by a retainer 37 which is biased to the right by a return spring 36 which returns the valve body 4 to the inoperative position.

The valve body 4 and the power piston 8 connected thereto are normally held in the illustrated inactive position by a return spring 36. In this non-operating state, the key member 22 comes into contact with the inner surface of the rear shell 3, thereby restricting the rightward movement of the valve plunger 19 and holding the valve plunger 19 at the backward limit position. When the input shaft 20 is not in operation,
The key member 22 is in an advanced position relative to the valve body 4, and at this time the valve body 26 is in the first position.
Both the valve seat 27 and the second valve seat 28 are seated, and the variable pressure chamber 10 is isolated from both the atmosphere and the constant pressure chamber 9. Therefore, during braking, when the valve plunger 19 is actuated by the advancement of the input shaft 20, the valve body 26 and the first valve seat 27 are immediately separated,
The variable pressure chamber 10 and the atmosphere are immediately communicated with each other.

The constant pressure chamber 9 communicates with, for example, an intake manifold of an engine (not shown) via a negative pressure introduction pipe 38 attached to the front shell 2. Therefore, negative pressure is always introduced into the constant pressure chamber 9.

Next, the operation of this embodiment will be explained.

When the brake booster 1 is in the non-operating position shown, the pressure in the variable pressure chamber 10 is slightly higher than the pressure in the constant pressure chamber 9, and is approximately balanced with the elastic force of the return spring 32.

When the brake pedal is depressed during braking, the input shaft 20 moves forward toward the valve body 4. As the input shaft 20 moves forward, the valve plunger 1
9 moves forward with respect to the key member 22 and the valve body 4. When the valve plunger 19 moves forward, the first valve seat 27 separates from the valve body 26 of the control valve 24 .
Therefore, air at atmospheric pressure enters the sixth hole 17 and the valve body 26.
and the first valve seat 27, the fourth hole 15, the third
It flows into the variable pressure chamber 10 through the passage 14a of the hole 14 and the passage 23. Furthermore, the air that has flowed into the variable pressure chamber 10 leaks into the first hole 12 through the gap between the valve body 4 and the valve plunger 19 in the second hole 13, and this leaked air flows into the reaction disk 30.
It comes to act on the rear end surface of. however,
Since atmospheric pressure is always acting on the front surface of the reaction disk 30, that is, the side surface of the output shaft through the atmospheric passage, there is almost no pressure difference that would cause a force to move the reaction disk 30 away from the protrusion 4a. . Therefore, the reaction disk 30 is attached to the protruding end surface 4 of the valve body 4.
There is no such thing as leaving a. As a result, the airtightness between the reaction disk 30 and the valve body 4 is reliably maintained, so that the air leaking into the first hole 12 is prevented from further leaking toward the constant pressure chamber 9. As a result, output loss caused by air leaking to the constant pressure chamber 9 side is prevented.

The air flowing into the variable pressure chamber 10 operates the power piston 8 and moves the valve body 4 forward, so the brake booster 1 generates an output via the output shaft 29 to operate the piston of the master cylinder. However, due to various resistances in the brake circuit after the master cylinder, no braking effect occurs yet. At the beginning of such operation,
Predetermined gaps are formed between the spacing member 35 and the reaction disk 30 and between the spacing member 35 and the valve plunger 19, so that the valve plunger 19 and the reaction disk 30 can be connected via the spacing member 35. There is no engagement.

Once the aforementioned resistances have been overcome, braking can begin. At this point, the gap between the reaction disk 30, the spacing member 35 and the valve plunger 19 is absorbed, so that the reaction disk 30 and the valve plunger 19
5 to engage with each other. Therefore, the reaction force due to braking is applied to the output shaft 29 and the reaction disk 3.
0 is transmitted to the driver via the spacing member 35, the valve plunger 19 and the input shaft 20. By this time, the output has already become quite large compared to the input, and a so-called jumping effect takes place. In that case, reaction disk 3
Since the atmospheric pressure that presses 0 is almost constant, the jumping characteristics are stable.

When the brake pedal is released to release the brake, the input shaft 20, the valve plunger 19, and the key member 22 are all moved rearward with respect to the valve body 4 until the key member 22 abuts the rear end wall of the hole 21.
In other words, move to the right. As the valve plunger 19 retreats, the first valve seat 27 comes into contact with the valve body 26 to shut off the variable pressure chamber 10 and the atmosphere, and the valve body 26
is separated from the second valve seat 28 and the variable pressure chamber 10 and constant pressure chamber 9
communicate with. As a result, the air in the variable pressure chamber 10 flows into the constant pressure chamber 9 and further flows into the intake manifold through the negative pressure introduction pipe 38. In that case,
The valve plunger 19 is at the most retracted position with respect to the valve body 4, and the gap between the valve body 26 and the second valve seat 28 is maximized. Therefore, the air in the variable pressure chamber 10 comes to flow quickly. Therefore, the valve body 4 and the power piston 8 are quickly retracted by the elastic force of the spring 36.

When the key member 22 comes into contact with the inner surface of the rear shell 3, the valve plunger 19 and the key member 22 no longer move back, but the valve body 4 continues to move back further. When the second valve seat 28 comes into contact with the valve body 26, the air in the variable pressure chamber 10 will no longer flow out toward the constant pressure chamber 9, so the power piston 8 will no longer retreat and will be at the backward limit position. The valve body 4 and the valve plunger 19 are thus in the initial inoperative position shown.

The retainer 37 for preventing the output shaft 29 from coming off in the negative pressure booster of the present invention configured as described above
In this case, it is only necessary to have a function to prevent the output shaft 29 from coming off, so that it can be formed from a simple soft iron material. Moreover, since there is no need to form a spring means as in the conventional case, there is no need to mold the retainer 37 for forming the spring means.
Therefore, the retainer 37 can be manufactured extremely easily and at low cost.

Note that the present invention is not limited to the above-described embodiments, and various design changes are possible.

For example, in the embodiment described above, the reaction disk 30 and the valve plunger 19 are used as a negative pressure booster.
Although the description has been made using the negative pressure booster 1 in which the spacing member 35 is provided between the two, the present invention can also be applied to a negative pressure booster that does not use such a spacing member 31. Similarly, it is also possible to apply the present invention to a type of negative pressure booster in which the valve body 26 and the second valve seat 28 are separated from each other during non-operation so that the variable pressure chamber 10 and the atmosphere communicate with each other.

Further, in the above embodiment, the valve body 4 and the power piston member 6 are formed separately, but the present invention can also be applied to a negative pressure booster in which these are formed integrally.

Further, although the above-mentioned embodiment describes the case where the negative pressure booster of the present invention is applied to a brake booster, the present invention can also be applied to other boosters such as a clutch booster. Can be applied.

(Effects of the invention) As is clear from the above explanation, according to the negative pressure booster according to the invention, atmospheric pressure is always applied to the side surface of the output shaft of the reaction disk, so there is no The reaction disk no longer moves forward during reaction force. Therefore, airtightness between the reaction disk and the valve body is reliably maintained, and output loss at the initial stage of operation can be effectively prevented.

Further, since only a substantially constant atmospheric pressure acts on the reaction disk, there is almost no variation in the jumping load, and the negative pressure booster can have good jumping characteristics.

Further, since the retainer for preventing the output shaft from coming off only has to have a function of preventing the output shaft from coming off, molding for the spring means as in the conventional art is not required. Therefore, not only is it easier to manufacture the retainer;
Since soft iron can be used as the material, it can be manufactured at a lower cost.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view showing an embodiment of the negative pressure booster according to the present invention applied to a brake booster, and FIG. 2 is an enlarged view of the vicinity of the reaction disk used in this booster. A is a partially enlarged view showing the state at the time of assembly, and B is a partially enlarged view showing the state after introducing negative pressure. 1... Brake booster (negative pressure booster), 4
... Valve body, 19 ... Valve plunger, 20
...Input shaft, 24...Control valve, 29...Output shaft,
30... Reaction disk, 31... Hole (atmospheric passage), 34... Female screw hole (atmospheric passage).

Claims (1)

[Claims for Utility Model Registration] A valve body that is arranged to be movable forward and backward in a space formed by a front shell and a rear shell, and that penetrates the rear shell in an airtight and slidable manner, and is connected to this valve body. and a power piston that divides the space into a constant pressure chamber into which negative pressure is introduced and a variable pressure chamber into which negative pressure is introduced during non-operation and atmospheric pressure is introduced during operation, and a power piston formed in the valve body. a valve plunger slidably disposed in the axial through hole; an input shaft connected to the valve plunger and disposed so as to be movable in the valve body; and an input shaft provided in the valve body and connected to the valve plunger. a control valve that is actuated to selectively communicate the variable pressure chamber with the atmosphere or the constant pressure chamber; an output shaft into which is fitted and a front end of which protrudes outside through the front shell, and a recess formed in the rear end of the output shaft;
A negative pressure booster comprising a reaction disk disposed to face the axial through hole, further comprising a hole inside the output shaft that communicates the recess of the output shaft with the outside. A negative pressure booster characterized in that the hole is bored and an atmospheric passage is formed through the hole to introduce atmospheric air to the side surface of the output shaft of the reaction disk.