JPS5918058A - Hydraulic servo brake - Google Patents

Abstract

PURPOSE:To reduce ineffective stroke with a simple constitution by providing a second path affording communication between two pressure chambers of a hydraulic servo brake and opening the path in the backward movement of a piston and closing the path in the forward movement of the piston with a valve mechanism. CONSTITUTION:A power piston 5 is formed with a second path 20 affording communication between a negative pressure chamber 13 and a transformation chamber 14. The path 20 is provided with a second valve mechanism 26 which is constituted from first and second lever members 26a, 26b. When a valve plunger 23 advances in braking, the valve mechanism is changed over in the same manner as prior one to introduce the atmospheric pressure into the chamber 14 and advance a power piston 5. Since then the force of the valve plunger 23 does not act on the second lever member 26b through the first lever member 26a, the member 26b closes the path 20 by a spring 43 and the atmospheric pressure. When the braking is released and the valve plunger 23 retreats, the valve mechanism 28 is changed over while the lever member 26b opens the path 26 by the force of the valve plunger 23 to afford communication between both chambers 13, 14.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a brake booster, and more particularly, to a brake booster that completely improves brake feeling by reducing the invalid stroke wheel of the brake booster during brake operation.

In a brake booster, is it an operating lever that is linked to the brake pedal? The opening and closing of the valve mechanism is controlled through the valve mechanism, and 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.
When the brake is released, communication between the variable pressure chamber and the atmosphere is completely cut off, the variable pressure chamber is communicated with the negative pressure chamber, and the power piston is returned to the non-operating position by a return spring. In order to completely improve the responsiveness of the brake booster, it is preferable to increase the flow area between the 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. If you increase the lift amount of the valve mechanism to increase the flow path area between the variable pressure chamber and the negative pressure chamber,
The disadvantage is that the amount of invalid stroke of the brake pedal required from the non-operating state to when the brake pedal is depressed and the valve mechanism blocks the communication between the variable pressure chamber and the negative pressure chamber increases, resulting in poor brake feeling. was there.

In order to eliminate such drawbacks, conventionally, a stopper member is attached to the valve plunger that constitutes the above-mentioned valve mechanism and is connected to the tip of the operating rod, and when the brake booster is not in operation, the stopper member is attached to the inner surface of the shell, etc. Accordingly, a device has been proposed that reduces the amount of invalid stroke of the brake pedal when the brake pedal is depressed.

However, with this configuration, the stopper member has a complicated shape and is not easy to manufacture, and there are also problems in that abnormal noise is generated due to contact between the stopper member and the shell.

In view of the above points, the present invention provides a complete brake booster capable of suppressing the invalid stroke amount of the brake pedal without providing a special stopper member, and which has a plurality of pressure chambers partitioned and formed. a shell, a tower piston provided within the shell so as to be movable forward and backward, and a valve that opens and closes a passage communicating between the pressure chambers in conjunction with a brake pedal to create a pressure difference between the pressure chambers. The brake booster includes a mechanism in which the power piston fully advances and retreats within the shell in response to this pressure difference, a second passage that allows full communication between the pressure chambers, and a second passage that opens and closes the second passage. The valve mechanism and metal fittings, gah, this second valve mechanism? , a first lever member that rotates in conjunction with the brake pedal, and a second lever member that opens and closes the second passage by rotating in the opposite direction to the rotation of the first lever member. The second valve mechanism opens the second passage when the piston moves backward, and closes the second passage when the piston moves forward.

The present invention will be explained below with reference to illustrated embodiments. In FIG. 1, it is constructed by abutting a shell (1), a front shell (2), and an azinyl (8), and the outer peripheral edge of a diaphragm (4) is held in the abutting portion. Power piston (5) U % It is supported in the shell (1) so that it can move forward and backward, and the inner peripheral edge of the diaphragm (4) is fitted onto the outer periphery of its tip and supports the front surface of the diaphragm (4). A diaphragm plate (6) is attached to the rear cylindrical portion (γ) and slidably projects from the opening of the laria shell (8) through a seal (8). On the other hand, the proximal end fitting portion (11) of the driven rod α0) is slidably fitted into the fitting hole (9) bored in the center of the front surface of the power piston (5). The tip of this driven rod (10) seals (+2) the end wall of the front shell (2).
? : Is it airtight? It is designed to pass through the cylinder and transmit the entire output to a master cylinder (not shown).

Inside the shell, the power piston (6), diaphragm (4), and diaphragm plate (6) are divided into a l:9 negative pressure chamber α3) and a variable pressure chamber (L41. The inside of the negative chamber 11B is a negative pressure pipe. It communicates with a negative pressure source such as the engine intake pipe through α5) and is constantly under negative pressure, but as described later, atmospheric pressure is introduced into the variable pressure chamber (inside the rod in conjunction with the depression of the brake pedal (not shown). As a result, the power piston (5) etc. receive a pressure difference between the two chambers (18) and 1' (141), and the return spring < r6 move forward,
Brake hydraulic pressure is generated in the master cylinder via the driven rod 110).

The power piston (5) is provided with a passage that allows communication between the negative pressure chamber (+3) and the variable pressure chamber (group), and a valve mechanism that opens and closes this passage and introduces atmospheric air into the variable pressure chamber. In other words, the passage (17) is connected to the internal chamber (18
), while a passage α9) is formed at the base of the cylindrical portion (7) to constantly communicate the internal chamber 08) and the variable pressure chamber (141). It is possible to communicate with 141 through an internal chamber <18).
A second passage @Q is formed at the tip of the power piston (6) and is capable of direct communication with the negative pressure chamber (13) and variable pressure chamber o4.

The valve mechanism that cuts off the communication between the passages (1η, a9) and opens and closes the @2 passage Q1 is operated by the operation lever (zll) as described below.
It is set in.

Operation rod 121'l n % Air 17-su from the rear opening of the cylinder part (7)! 38.1 It protrudes through the ffi and is connected to the brake pedal at its protrusion, and transmits the pedal force acting on the brake pedal to the master cylinder.

The valve plunger Hd, which is provided by caulking the tip spherical part (-) of this operating rod (211), is slidably fitted into the shaft hole (9) of the power piston (5), and in the non-operating state shown in the figure, Opposed to the above-mentioned working rod fitting part (to the reaction disk fitted in 11), the operating rod +211
When it is fully advanced, it comes into contact with this example of the reaction disk, which fully valves and suppresses the driven rod (10).

Therefore, in the small diameter part (2) of the valve plunger and the through hole (27) of the power piston (6), there is a first lever member (26a) and a second lever member (26b). 2
A valve mechanism (26) is provided, and one end of the first lever part (26a) is movably engaged with the central small diameter part (23a) of the valve plunger part, and the other end is engaged with the power piston (5). ) through hole (extends to approximately the center of i of 2η).

One side of this first lever member (26a) ((formed protrusion)
26c) is in contact with the rear side wall surface of the through hole 7), and the first
The lever member (26a) rotates using the temple protrusion (26c) as a fulcrum.

A second lever member (:2
6b) In I, the protrusion (26) of the first lever member is provided on one side.
forming a protrusion (26d) i that protrudes in the opposite direction to c);
This protrusion (26a) is in contact with one wall surface on the front side of the through hole (z7).

Further, the lower end of the second lever member (26b) has a through hole j.
The protruding part of the spring seat (for the inner circumferential beat part of the diaphragm (4)) that protrudes from faJ and faces the opening of the second passage (26b) It is biased toward the J Niji opening side by a spring provided between the

The valve plunge yard has a relative displacement with the first lever member (26a) and a displacement between the first lever member (26a) and the second lever part 1.
(26b) It is possible to move relative to the power piston (5) in the front and back direction within the permissible range of relative displacement with respect to the tonneau power piston (5).

Behind the spherical part of the operation lever (21i) is a passage (17, l).
, (valve member 128 for communicating and cutting off the oil amount) is provided. This valve member example has an impaction plate member (covered with an elastic member such as 291't rubber), has a substantially cylindrical shape, and has a rear edge enlarged portion Mk in the middle of the cylindrical portion (7). The valve return spring (33) is fitted and fixed to the circumferential part.A valve return spring (33 ) is provided, and a valve biasing spring +344 is elastically loaded between the rear step part of one example of the valve member and the receiving part C321.Therefore, in the non-operating state, the valve plunger 3) of the return spring
The valve plunger (26=) of the first lever i4 is energized to the right in Fig. 1 together with the operating lever (211) due to the biasing force of
The part that engages with 2J3+ moves to the right, and the part that engages with the first lever member (26
The part that comes into contact with the second lever part (261)) in a) is the second
This part of the lever part (26b) is fully pressed and both are in a leftward position. Therefore, the protruding portion from the through hole 71 of the second lever member (26b) moves to the right against the spring (g), and is inclined with respect to the opening of the second passage (201). This opens the second passage.Also, the valve member t28
1 U, valve biasing spring (energized by the wholesaler and valve plunger (
231 valve seat flame) to shut off the inside of the shell (1) from the atmosphere.

However, in this non-operating state, the power piston (
5) i, J: are moved to the right side in Figure 1 by the return spring (■6), and the protrusion formed on the diaphragm (4) is brought into elastic contact with the inner surface of the rear shell (3) and stopped. There is.

In the above situation, the brake pedal may become loose and the operating lever (21
) moves forward against the valve return spring +331K.
The valve member (28) c'i is in elastic contact with the valve seat formed in the Hower piston (5) and is connected to the passage (17) and the internal chamber (I8).
).

Furthermore, when the operating rod (211) moves forward, the valve pusher (c) moves forward and comes into elastic contact with the reaction disk, but the valve member μs locks on the valve seat (plate), so the valve The valve seat f35) i of the plunger example is separated from the valve member (28), and air enters the variable pressure chamber (inside the river (see Fig. 2) through the passage (+9) f. As a result, the valve plunger (4) ) engaged with the first lever member (26a
) u Released from the state of being pressed to the right, the protrusion (26c) H of the first lever member (26a) does not function as a fulcrum of the lever, so the first lever member (26b) comes into contact with the second lever member (26b). No leftward force is applied to the lever member (26a).

Therefore, the second lever member (26b) has a first lever portion (
Since no force is applied from 26a), the second lever member (
26b) Fi is able to move freely forward, and with the atmospheric pressure acting from the rear, the elastic force of the b spring tK31 that presses from the rear causes it to come into close contact with the seal (39) of the second passage (20) k- Promptly closed, negative pressure chamber 03
) and the variable pressure chamber (I41) are completely cut off. Also, the power piston (5) moves forward against the return spring σ6, which is energized by the atmospheric pressure introduced into the variable pressure chamber (141), and the driven rod αO) Operate the master turn cylinder to supply brake fluid pressure to the brake cylinder.

When the pedal force is removed from the brake pedal, the valve plunger) is activated by the valve return spring 1331 IC, 1: the operating rod (21).
1 and moved to the right relative to the power piston (5). Then, first, the valve seat (35) of the valve plunger comes into close contact with the valve side (capture) to shut off the inside of the shell (1) from the atmosphere.

As the valve granger (valve member) separates from the valve seat 135 as the toughness retreats, the variable pressure chamber (IJ total negative pressure chamber (13)
), and the second lever member (26b) is separated from the seal (39) by the force of the first lever member (26a) to open the second passage (201k (see FIG. 6))1.
As a result, the variable pressure chamber (14) communicates with the negative pressure chamber (13) via a flow path with a large flow area, and the variable pressure chamber (14)
41 quickly becomes the same pressure as the negative pressure chamber (I3), the power piston (5) return spring (I6)
) to retreat quickly due to the force of the attack. Note that when the second lever member (26b) opens the second passage, the air in the variable pressure chamber (1B) is sucked into the negative and positive chamber (1B) along the second passage (201). In order to ensure smooth air flow, the second lever member (
26b) The part (g) where the ends face each other is slightly recessed than the other parts (see Fig. 6). The azinyl (3) is displaced to the right by the elastic force of the diaphragm (4) and the protrusion of the diaphragm (4) is
When it comes into elastic contact with the inner surface of the power piston (5
) has completed its backward movement, and the position shown in FIG. 1 is reached. That is, the valve plunger ＼j1 1st. Second lever member (26a), (26b
), the valve portion 15A (end)), etc., are completely the same in the backward operation and in the non-operation, as can be understood by comparing FIGS. 1 and 6.

Now, when the operating rod 1211' is moved forward again from the non-operating position via the brake cylinder, the valve member! 28) is seated on the valve seat t38), and the valve plunger t38) is separated from the valve part side (end), and the atmosphere is introduced into the variable pressure chamber (inside the power piston). Switching the flow path in (5) requires at least a lift amount (δ.) until the valve member □□□) comes into contact with the valve seat μs), and this becomes an invalid stroke. In the example, this lift amount (δ
. ) are set to the minimum required. This is because when the power piston (5) retreats, the variable pressure chamber 0 and the negative pressure chamber (1
3) What is the second passage f? 0), and is connected to the transformation chamber (14
) quickly becomes the same pressure as the negative pressure chamber (13). Therefore, the ineffective stroke number of Kamimasaomi is very small, and the responsiveness during brake operation is extremely good.Furthermore, since the second passage (2+υ·r) is provided, the brake can be released quickly. Especially the second lever (
26b) Since the passageway (20Ji) is opened in an inclined state with respect to the opening of the entire 21st street (20), a large flow passage area can be secured.

In addition, Ben Plunga country) Toriaku/Conde r Sufu lament)
The facing distance (δ2) is approximately the same as the vertical distance (δ0).

FIG. 4 shows the entire second embodiment of the present invention, which differs from the first embodiment in that the first lever member (26a) and the second lever member (26b) are held together. 1st lever part 4'J
(26a) is drilled with a hole 511K, and the end of the second lever set (26b) is formed with a protrusion (circle) that can be fitted into the hole (Fig. 5). According to this configuration, the first lever section (26a) and the second lever section (2'
This can be achieved by completely preventing any misalignment of the part that contacts 6b).

As described above, according to the present invention, it is possible to obtain a brake booster that has a simple configuration, minimizes the invalid stroke, and has good operating characteristics. In particular, since the second valve mechanism that fully opens and closes the second passage is formed by a pair of lever members, a larger total flow area can be secured when the passage is opened.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the first embodiment of the present invention, FIG. 2 is a cross-sectional view of the main part showing the state in which the valve plunger is separated from the valve member, and FIG. 6 is when the power piston is retracted. 4 is a cross-sectional view of the main parts shown in the second embodiment of the present invention,
FIG. 5 is a perspective view of a pair of lever members in the second embodiment vc, and FIG. 6 is a cross-sectional view taken along the Vl mound of FIG. 1. (1) Nigel (5): Power piston αB
): Pressure chamber (negative chamber) 04: Pressure chamber (variable pressure chamber) η, α: Passage (201: Second passage @j):
Second valve mechanism (26a): First lever member (26b
): Second lever member (26c): Protrusion on the first lever part (26d): Protrusion on the second lever member (157+): Through hole (28): Valve mechanism (valve member) procedure amendment (Voluntary) 1. Indication of the case Patent Attorney No. 128414 of 1989 2 Name of the invention Brake booster 8 Relationship with the person making the amendment Notes Patent applicant 4, agent 5, of the specification to be amended "Air cleaner
38) Correct the description J to [Air Cleaner I; 3G) J.

Claims (1)

[Claims] (1) A shell having a plurality of pressure chambers defined therein, a power piston provided within the shell so as to be movable forward and backward, and communicating between the pressure chambers in conjunction with a brake pedal. The brake booster is equipped with a valve mechanism that opens and closes a passage to create a pressure difference between these pressure chambers, and the power piston moves fully forward and backward within the shell in response to this pressure difference. a second valve mechanism that opens and closes the second passage; and a first lever member that rotates the second valve mechanism in conjunction with the brake pedal. and the rotation of this first lever member [, J: the second lever il which is rotated in the opposite direction to open and close the second passage.
1. A brake booster, characterized in that the second valve mechanism opens the second passage when the piston moves backward, and closes the second passage when the piston moves forward. (2) The brake booster according to claim 1, wherein the Hz 2 valve mechanism is disposed in a through hole formed in the power piston. (8) The first lever member is rotated using the protrusion 18k as a fulcrum that abuts on the rear side wall surface of the through hole of the Hahower piston, and the second lever member is rotated using the protrusion that abuts on the front side wall surface of the through hole as a fulcrum. A brake booster according to claim 2. (4) The first lever member is operated by engaging with a valve plunger that is linked to a brake pedal.
The brake booster according to any of paragraph 6.