JP2853303B2 - Valve mechanism of brake booster - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a valve mechanism of a brake booster, and more particularly, to a valve mechanism of a brake booster capable of improving responsiveness during operation. .

"Conventional technology" Conventionally, as a valve mechanism of a brake booster, a constant pressure valve housed in a valve body slidably provided in a shell and switching a communication state between a constant pressure chamber and a variable pressure chamber formed in the shell. And a pressure valve body for switching a communication state between a variable pressure chamber in the shell and a pressure fluid source, and switching a fluid circuit in conjunction with an input shaft is known.

[Problems to be Solved by the Invention] By the way, it has been conventionally demanded to improve the responsiveness when the brake booster is operated. In the valve mechanism described above, the flow path area when the pressure valve is opened may be increased, but in that case, there are the following problems.

That is, the pressure valve in the above-described conventional valve mechanism has a flange-shaped valve seat formed on an input shaft penetrated through the valve body, and the valve body is brought into contact with and separated from the valve seat from the rear side. In the above, a single pressure valve is constituted by a pair of valve seats and a valve body.

Therefore, in the above-described conventional configuration, in order to increase the flow path area of the pressure valve at the time of opening, as a first method, it is conceivable to expand a contact portion between a valve seat and a valve body in a radial direction. As a second method, it is conceivable to increase the axial distance between the valve seat and the valve body when the valve seat is opened.

However, even if these methods are adopted, it is difficult to increase the installation space in the radial direction or the axial direction of each of the above members due to the relationship with other adjacent components, or the valve seat and the valve Due to the difficulty in ensuring sufficient strength of the body, there is a limit to increasing the flow area of a single pressure valve in the above-described manner.

Means for Solving the Problems In view of such circumstances, the present invention relates to a valve mechanism of the above-described brake booster, wherein the constant pressure valve is formed in the valve body and communicates with a pressure fluid source. A first spring provided in the fluid passage and urged forward by a spring;
An input having a valve body and a first valve seat formed on a valve body on which the first valve body is seated; and a cylindrical movable member provided through a shaft of the first valve body. The movable member is loosely fitted to the outer peripheral portion of the shaft so as to be reciprocally movable within a required range in the axial direction, and the movable member is biased toward the rear side by a spring, so that the inner peripheral surface of the movable member and the input shaft are The space formed by the outer peripheral portion communicates with the pressure fluid source. Further, the pressure valve is connected to an annular second valve body provided at a predetermined position on the outer peripheral portion of the input shaft, and the second valve body slides against the second valve body. A first pressure valve including a second valve seat formed on a front-side inner peripheral surface of the movable member; a third valve seat formed on a rear-side outer peripheral portion of the movable member; And a second pressure valve comprising a first valve body.

[Operation] According to such a configuration, since the pressure valve is composed of the first pressure valve and the second pressure valve, the pressure valve is compared with a conventional single pressure valve. Thus, the flow path area when the pressure valve is opened can be increased.

As a result, the amount of pressure fluid introduced per unit time when the pressure valve is opened can be increased as compared with the conventional case where only a single pressure valve is provided. Thus, the responsiveness of the brake booster at the time of operation can be improved.

Embodiment The present invention will be described below with reference to the illustrated embodiment. In FIG. 1, the inside of a sealed container constituted by a front shell 1 and a rear shell 2 is divided into front and rear front chambers 4 by a center plate 3 provided at the center thereof. And a rear chamber 5, and a substantially cylindrical valve body 6 is slidably mounted on the shaft portions of the rear shell 2 and the center plate 3 while maintaining airtightness by annular seal members 7 and 8, respectively. Through.

A front power piston 9 and a rear power piston 10 housed in the front chamber 4 and the rear chamber 5 are connected to the valve body 6, respectively, and a front diaphragm 11 and a rear diaphragm 11 are provided on the rear surfaces of the power pistons 9 and 10, respectively. The constant pressure chamber A and the variable pressure chamber B are formed before and after the front diaphragm 11, and the constant pressure chamber C and the variable pressure chamber D are also formed before and after the rear diaphragm 12.

The constant pressure chamber A of the front chamber 4 communicates with an atmosphere passage 17 formed in the cylindrical portion 6a of the valve body 6 through an axial constant pressure passage 16 provided in the valve body 6, and is provided in the valve body 6. It communicates with the constant pressure chamber C of the rear chamber 5 through another axial constant pressure passage 18. Then, a negative pressure can be introduced into the constant pressure chamber A of the front chamber 4 through a negative pressure introducing pipe 19 attached to the front shell 1.

On the other hand, the variable pressure chamber B of the front chamber 4 is communicated with a variable pressure chamber D of the rear chamber 5 through a variable pressure passage 20 formed in the valve body 6, and the variable pressure chamber D of the rear chamber 5 is formed in the valve body 6. The air passage 17 communicates with the atmosphere passage 17 via a radial pressure transformation passage 21.

The atmosphere passage 17 communicates with the atmosphere through a filter 22, and an atmosphere passage located inside the filter 22.
17 is provided with a valve mechanism 23 for switching a fluid circuit between the constant pressure chambers A and C and the variable pressure chambers B and D. As detailed later,
The valve mechanism 23 is operated in conjunction with the input shaft 24. When the input shaft 24 is advanced in conjunction with a brake pedal (not shown), the valve mechanism 23 is also operated, and the constant pressure chamber A is operated. , C and the transformation chambers B, D are cut off, while the atmosphere is introduced into the transformation chambers B, D via the atmosphere passage 17 and the transformation passages 20, 21. As a result, the valve body 6 is advanced, and the output shaft 25 having the base mounted on the valve body 6 is moved.
Thus, an output of a predetermined servo ratio can be obtained from.

In a non-operating state of the tandem brake booster shown in FIG. 1, the valve body 6 is urged toward the rear side by a return spring 26 provided between the valve body 6 and the front shell 1, and the above-described input is performed. The valve body 6 is stopped at a position where the valve plunger 31 constituting the shaft 24 and the key member 32 engaging with the valve body 6 come into contact with the wall surface of the rear shell 2.

The configuration of the valve mechanism 23 will be described in detail with reference to FIG. 2. The valve mechanism 23 is an annular second valve formed in a step portion of the valve body 6 in which the constant pressure passage 16 opens to the atmosphere passage 17. One valve seat 33 and a spring 34
And a first valve body 35 seated on the first valve seat 33. In the present embodiment, the first valve seat 33 and the first valve body 35 seated thereon constitute a constant pressure valve 36 for switching the communication between the constant pressure chambers A, C and the variable pressure chambers B, D. .

The input shaft 24 formed by connecting the valve plunger 31 on the front side and the operating rod 37 on the rear side passes through the shaft portion of the first valve body 35. An operating rod 37 is pivotally connected to the valve plunger 31, and these connecting portions are connected to the first valve seat 33.
The first valve body 35 is seated on the rear side of the distal end of the first valve body 35.

An operating rod 37 of the input shaft 24 is connected to a brake pedal (not shown) by penetrating the filter 22 and then protruding to the outside of the cylindrical portion 6a, and a spring 34 for urging the first valve body 35. Is provided over the outer peripheral portion of the operating rod 37 and the back surface of the distal end portion of the first valve body 35.

On the other hand, the valve plunger 31 of the input shaft 24 has its front side slidably fitted in an axial hole formed in the valve body 6 and has an annular groove 31 a formed in the center of the valve plunger 31. The key member 32 is engaged.

An annular recess is formed by a pair of flange portions 31b and 31b 'in the outer peripheral portion of the valve plunger 31 adjacent to the annular groove 31a, and a second valve body 38 made of an annular elastic body is attached to the annular recess. In addition, a knurl portion 31c having an outer diameter smaller than the outer diameter of the flange portion 31b 'is formed on the outer peripheral portion of the valve plunger 31 further on the rear side than the rear flange portion 31b'. .

A stepped cylindrical movable member 39 is loosely fitted from the rear side to the valve plunger 31 configured as described above, and the valve plunger 31 is inserted into the internal space of the large-diameter portion of the movable member 39 on the front side. And the second valve body 38 is housed, and the tip of the second valve body 38 is slidably contacted with a second valve seat 39a formed on the inner peripheral surface of the large diameter portion of the movable member 39. I have.

The large diameter portion of the movable member 39 having the second valve seat 39a is formed with a plurality of slits 39b extending over a predetermined range from the left edge to the rear side in the axial direction. When the valve element 38 is in sliding contact with the position of the slit 39b of the second valve seat 39a, the space inside and outside the movable member 39 communicates. On the other hand, when the second valve body 38 comes into sliding contact with the second valve seat 39a on the rear side of the position of the slit 39b, communication between the space inside and outside the movable member 39 is prevented. In the present embodiment, the second valve body 38 and the second valve seat 39a constitute a first pressure valve 40 for switching the communication state between the above-described variable pressure chambers B and D and the atmosphere.

On the other hand, the small-diameter portion of the movable member 39 located on the ear side is slidably fitted to the knurl portion 31c of the valve plunger 31, and the step end face of the inner peripheral portion of the movable member 39 is
The flange portion 31b 'of the valve plunger 31 is opposed from the rear side. A ring-shaped stopper member 41 fitted to a predetermined position of the valve plunger 31 is opposed to the rear end of the movable member 39 fitted to the valve plunger 31 in this manner.

Since the distance between the flange portion 31b 'and the stopper member 41 in the valve plunger 31 is set longer than the axial dimension of the small diameter portion of the movable member 39, the movable member
Reference numeral 39 denotes a flange end of the valve plunger 31
The valve plunger is moved between a forward end position where it contacts the b ′ and a retreat end position where its rear end contacts the stopper member 41.
It can move in the axial direction relative to 31.

Since a plurality of slits are formed in the outer peripheral portion of the stopper member 41 and the flange portion 31b 'of the valve plunger 31, the inner space formed by the inner peripheral surface of the movable member 39 and the outer peripheral portion of the valve plunger 31 Is the first pressure valve
Atmosphere is introduced to 40 positions.

As shown in FIG. 2, when the step end surface of the movable member 39 is at the forward end position where it comes into contact with the flange portion 31b 'of the valve plunger 31, the second valve body 38 is moved to the second valve seat 39a.
, The first pressure valve 40 is closed. On the other hand, as shown in FIG.
When the rear end of the second valve body 38 comes to the retracted end position where it comes into contact with the stopper member 41, the second valve body 38 comes into sliding contact with the slit position in the second valve seat 39a, so that the first pressure valve 40 is opened. Therefore, the atmosphere is introduced into the variable pressure chambers B and D via the first pressure valve 40.

Further, a flange-shaped third valve seat 42 is formed on the outer peripheral portion on the rear side of the movable member 39, and a spring 43 is elastically mounted over the flange-shaped third valve seat 42 and the valve body 6. The entire movable member 39 is biased rearward. The outer periphery of the rear end of the movable member 39 urged by the upper spring 43 is loosely fitted to the shaft portion of the first valve body 35, whereby the third valve seat 42 is connected to the first valve 35. It faces body 35. Therefore, the third valve seat 42 and the first valve body 35 are
The springs 34 and 43 bias the springs 34 and 43 in a direction approaching each other. In the present embodiment, the third valve seat 42 formed on the movable member 39 and the first valve body 35 seated there are provided by the third valve seat 42. A second pressure valve 44 for switching the state of communication between the variable pressure chambers B and D and the atmosphere is provided.

In the non-operating state of the tandem brake booster shown in FIG. 2, when the first valve body 35 is separated from the first valve seat 33 (when the constant pressure valve 36 is opened). , Third
Since the valve seat 42 and the first valve body 35 are in pressure contact with each other, the second pressure valve 44 is closed.

On the other hand, as shown in FIG.
(Constant pressure valve 36 is closed)
, The movable member 39 is a stopper member of the valve plunger 31.
When the third valve seat 42 is pushed out toward the front side by engaging with the 41, the third valve seat 42 is forcibly separated from the first valve body 35, so that the second pressure valve 44 is opened. I have. At that time, the atmosphere introduced to the position of the second pressure valve 44 is introduced into the variable pressure chambers B and D via the second pressure valve 44.

In the present embodiment, the spring force of the spring 43 biasing the movable member 39 toward the rear side is smaller than the spring force of the spring 34 biasing the first valve body 35 to the front side. Is adopted. A valve return spring 45 having a greater resilience than the springs 34 and 43 is attached between the base of the first valve body 35 and the operating rod 37. The input shaft 24 is biased toward the rear side.

As described above, in the present embodiment, the valve mechanism 23 is configured by the two pressure valves including the first pressure valve 40 and the second pressure valve 44 and the constant pressure valve 36.

The operation of the valve mechanism 23 in the above configuration will be described with reference to FIGS. 2 to 4. First, as shown in FIG.
When the tandem brake booster is not operated, the constant pressure valve 36 formed by the first valve seat 33 and the first valve body 35 of the valve body 6.
Are open, the constant pressure chambers A, C and the variable pressure chambers B, D communicate with each other, and a negative pressure is introduced into each of the chambers. On the other hand, since the first pressure valve 40 and the second pressure valve 44 are both closed, the introduction of air into the variable pressure chambers B and D is prevented by the first pressure valve 40 and the second pressure valve 44. Have been.

Next, as shown in FIG. 3, when the driver depresses the brake pedal abruptly from the inoperative state, the input shaft 24 also rapidly advances (leftward). Therefore, first, the first valve body 35 is seated on the first valve seat 33 and the constant pressure valve 36 is closed, so that the communication between the constant pressure chambers A and C and the variable pressure chambers B and D is cut off.

Thereafter, with the rapid advance of the input shaft 24, the valve plunger 31 is advanced in the axial direction relatively to the movable member 39, so that the first pressure valve 40 is opened. The stopper member 41 of the valve plunger 31 is a movable member.
The third valve seat 42 provided on the movable member 39 is brought into contact with the first
The second pressure valve 44 is also opened because it is forcibly separated from the valve body 35. Therefore, the first pressure valve 40 and the second pressure valve
Atmosphere is quickly introduced into the transformation chambers B and D via the air passage 44.

As a result, as described above, a pressure difference is generated between the constant pressure chambers A and C and the variable pressure chambers B and D. The valve body 6 is advanced by the pressure difference, and an output having a predetermined servo ratio is obtained from the output shaft 25. It is supposed to be.

As described above, in this embodiment, when the brake pedal is suddenly depressed, the two pressure valves 40 and 44 are opened almost simultaneously, and the variable pressure chamber B is opened via the two pressure valves 40 and 44. , D can be introduced into the atmosphere. Thus, as compared with the conventional valve mechanism 23 having only a single pressure valve corresponding to the first pressure valve 40 of the present embodiment,
In the case of the present embodiment, the flow path area when the pressure valves 40 and 44 are opened can be increased, and the transformation chambers B and
Atmosphere can be quickly introduced into D.

Therefore, the responsiveness of the tandem brake booster at the time of operation can be improved as compared with the conventional valve mechanism 23 including only the single pressure valve described above.

FIG. 3 shows the operating state of the valve mechanism 23 when the brake pedal is suddenly depressed from the non-operating state, but FIG. 4 shows the state slowly from the non-operating state in FIG. This shows a state in which the brake pedal is depressed to operate the valve mechanism 23.

That is, when the brake pedal is slowly depressed from the non-operation state shown in FIG. 2, the first valve body 35 is first seated on the first valve seat 33 as shown in FIG. Are closed, and the communication state between the constant pressure chambers A and C and the variable pressure chambers B and D is cut off.

Next, in the case of FIG. 4, since the input shaft 24 is advanced slowly, the valve plunger 31
Becomes relatively axially advanced, so that
The first pressure valve 40 is opened. In the case of FIG. 4, since the input shaft 24 is advanced slowly, the valve plunger 31
Before the stopper member 41 abuts on the rear end of the movable member 39, the first pressure valve 40 is opened, so that the third valve seat 42 biased by the spring 43 is moved from the first valve body 35 Without being disengaged, the second pressure valve 44 remains closed.

Therefore, in the case of FIG.
Atmosphere is introduced into the variable pressure chambers B and D only through the pressure valve 40, and thereafter, the valve body 6 is advanced similarly to the case of FIG. You can get the output.

In the present embodiment, the first pressure valve 40 is connected to the second pressure valve 44.
Since it is located closer to the front side in the axial direction and closer to the variable pressure passage 21, the conventional valve in which a single pressure valve corresponding to the second pressure valve 44 is provided in the present embodiment. Mechanism 23
In comparison with the conventional one, the introduction path of the atmosphere can be shortened substantially by the distance between the first pressure valve 40 and the second pressure valve 44. The responsiveness at the time is improved.

FIG. 5 shows the state of the valve mechanism 23 in the process of returning from the operation state shown in FIGS. 3 and 4 to the non-operation state shown in FIG.

When returning from this operating state to the non-operating position,
The flange portion 31b 'of the valve plunger 31 abuts on the stepped end surface of the movable member 39 by the urging force of the valve return spring 45, thereby closing the first pressure valve 40, and the third valve seat 42 of the movable member 39. Since the first valve body 35 also presses against each other, the second pressure valve 44 is also closed. On the other hand, the first valve pair 35 is separated from the first valve seat 33 of the valve body 6 by the elasticity of the valve return spring 45 and the spring 43 provided on the movable member 39, so that the constant pressure valve 36 is opened.

Thereafter, the key member 32 engaged with the valve plunger 31 abuts against the inner wall of the rear shell 2 to prevent the valve plunger 31 and the valve body 6 from retreating, and thus returns to the inoperative state shown in FIG.

As described above, since the valve mechanism 23 of the present embodiment includes two pressure valves, that is, the first pressure valve 40 and the second pressure valve 44, the conventional valve mechanism 23 includes only a single pressure valve. As compared with the valve mechanism of the above, the flow path area when the pressure valve is opened can be increased, so that the responsiveness of the tandem brake booster at the time of operation can be improved.

In this embodiment, the first pressure valve 40 is connected to a movable member.
A second valve seat 39a formed in the large diameter portion of the first valve seat 39;
And the second valve seat 39a is formed of a front slit 39b and a rear slitless portion.

Then, based on the servo balance state in which the constant pressure valve 36, the first pressure valve 40, and the second pressure valve 44 are closed, the moment when the constant pressure valve 36 is opened while the first pressure valve 40 and the second pressure valve 44 are closed. The difference between the pedaling force and the pedaling force at the moment when the first pressure valve 40 is opened while the constant pressure valve 36 and the second pressure valve 44 are closed is
The second valve body 38 can be adjusted according to the length of sliding contact at a portion of the second valve seat 39a having no slit in the second valve seat 39a. Therefore, the magnitude of the hysteresis, which is the difference between the output when the brake pedal is depressed and the time when the brake pedal is released, can be set freely.

Although the above embodiment has been described with reference to the embodiment in which the present invention is applied to the tandem brake booster, the present invention can also be applied to a single type brake booster or a triple type brake booster. Further, it goes without saying that the present invention can be applied to a positive pressure type brake booster.

[Effects of the Invention] As described above, according to the present invention, an effect is obtained that the responsiveness of the brake booster at the time of operation can be improved as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG.
3 to 5 are enlarged sectional views showing states different from those in FIG. 6 Valve body 17 Atmospheric passage (pressure fluid passage) 33 First valve seat, 34 Spring 35 First valve body 36 Constant pressure valve 38 Second valve body 39 Movable member 39a Second valve seat, 40 First pressure valve 42 Third valve seat, 43 Spring 44 Second pressure valve A, C Constant pressure chamber, B, D Transformation Room

Claims (1)

(57) [Claims] 1. A constant pressure valve housed in a valve body slidably provided in a shell for switching a communication state between a constant pressure chamber and a variable pressure chamber formed in the shell, a variable pressure chamber in the shell and a pressure fluid. A pressure valve for switching a communication state with a pressure source, wherein the constant pressure valve is formed in the valve body and communicates with a pressure fluid source. A first valve body provided in the pressure fluid passage to be urged toward the front side by a spring, and a first valve seat formed in a valve body in which the first valve body is seated. The movable member is loosely fitted to the outer peripheral portion of the input shaft provided through the shaft portion of the first valve body so as to reciprocate within a required range in the axial direction, and the movable member is rearwardly moved by a spring. Biased toward the side, the movable A space defined by an inner peripheral surface of the material and an outer peripheral portion of the input shaft is communicated with the pressure fluid source. Further, the pressure valve is provided at a predetermined position on an outer peripheral portion of the input shaft. A first pressure valve comprising a second valve seat formed on a front inner peripheral surface of the movable member with which the second valve body slides; a third valve seat formed on a rear outer peripheral portion of the movable member; A valve mechanism for a brake booster, comprising: a second pressure valve including the first valve body which comes into contact with and separates from a third valve seat.