JPH0338052Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a brake booster, and more particularly to a brake booster equipped with a one-valve, two-seat type valve mechanism.

[Prior art] Generally, brake boosters (for example, November 1982)
26th, page 2-22 of “New Automotive Engineering Handbook (Part 5)” published by the Society of Automotive Engineers of Japan
86), the input and output in the intermediate load state have a proportional relationship called the servo ratio. Conventionally, it is known that there is a slight difference in output due to hysteresis when the input is set to a predetermined value when the brake is applied and when the input is set to the same predetermined value when the brake is released. Even if there is a difference in the output during operation, it is small, and moreover, from the proportional relationship of the servo ratio mentioned above, both are essentially the same, and the servo ratio can be changed freely between when the brake is applied and when the brake is released. could not be changed.

[Problems to be solved by the invention] By the way, a relatively large number of drivers tend to subconsciously loosen the force applied to the brakes when the vehicle is about to stop after applying the brakes. If the brake pedal force is relaxed, the output will naturally decrease while maintaining the above proportional relationship, so a slight decrease in the brake pedal force will cause a large drop in output, and the vehicle will stop due to an unconscious decrease in the brake pedal force. If the braking force is insufficient at the moment, the brakes will feel less effective as a whole.

In view of such circumstances, the present invention has been developed to obtain an effect equivalent to an increase in output even more than that obtained with a normal proportional relationship in an intermediate load state, and to automatically increase the output when the vehicle is about to stop. Even if the brake pedal force is loosened, the decrease in the brake pedal force is compensated for by the increase in the output, so that a good brake feeling without the feeling of insufficient braking force can be obtained.

[Means for Solving the Problems] That is, the present invention provides a brake booster equipped with a one-valve, two-seat type valve mechanism, that is, a valve plunger interlocked with an input shaft, a first valve seat formed on a valve body, and the above-mentioned components. A brake booster comprising a second valve seat formed on a valve plunger, and a valve body seated on the first valve seat and the second valve seat, wherein the second valve seat is seated on the valve body and the second valve seat on the valve plunger.
At least one of the valve seats is made of an elastic body, and an orifice passage is formed in which the flow path is blocked by elastic deformation of the elastic body when the valve body is seated on the second valve seat. .

[Operation] In the conventional brake booster, the above-mentioned valve body is
The moment the valve seat is seated, the supply of pressure fluid to the variable pressure chamber is stopped. According to the above configuration, the orifice passage is opened at this moment, and pressure fluid is gradually supplied to the variable pressure chamber through the orifice passage. When the fluid pressure in the variable pressure chamber increases and the valve body and second valve seat are strongly pressed against each other, the orifice flow path is blocked by elastic deformation of the elastic body.

The state in which the orifice flow path is blocked is the original servo balance state, and Figure 4 shows the original characteristic curve A when the orifice flow path is blocked and the moment when the valve body seats on the second valve seat. Characteristic curve when the orifice flow path is still open
A' is shown.

As mentioned above, the state where the orifice flow path is blocked is the original servo balance state, but
The moment the valve element seats on the second valve seat, the supply of pressure fluid to the variable pressure chamber is almost stopped. It feels like the brake operation is being performed based on the instantaneous characteristic curve A'.

When an attempt is made to stop the vehicle by maintaining the brake pedal force at point Q' on the characteristic curve A', if the brake pedal force is continuously maintained,
Pressure fluid is gradually supplied to the variable pressure chamber through the orifice flow path, so the output gradually increases, and at point Q on the characteristic curve A, the orifice flow path is shut off and a servo balance state is established.

As a result of such an effect, the driver tries to stop the vehicle by maintaining the brake pedal force at point Q' on the characteristic curve A', and just before the vehicle stops, the driver unconsciously reduces the brake pedal force at point Q' on the characteristic curve A'. Even if the curve is loosened, the curve only decreases from point Q to point R on the characteristic curve A.

In other words, the driver intuitively feels that the
Even if the brake pedal force is unconsciously relaxed when trying to obtain the output of Q', the actual output will be an output R close to the above Q'. As a result, it is possible to obtain a good brake feeling with a feeling of brake bite.

[Example] The present invention will be explained below with reference to the illustrated example.
In FIG. 1, 1 is a front shell, 2 is a rear shell, and a power piston 3 and a diaphragm 4 stretched on the back side of the power piston 3 are provided in a sealed container composed of both shells 1 and 2.
The power piston 3 and the diaphragm 4 partition the inside of the shells 1 and 2 into a constant pressure chamber 5 at the front and a variable pressure chamber 6 at the rear.

A valve body 7 is integrally provided on the shaft portion of the power piston 3, and a valve mechanism 8 for switching the fluid circuit is housed within the valve body 7, and the base of a push rod 9 serving as an output shaft is slidably fitted into the valve body 7. I'm keeping it. The power piston 3, valve body 7, etc. are normally held in the non-operating position shown in the figure by a return spring 10.

The valve mechanism 8 includes a first valve mechanism provided in the valve body 7.
It includes a valve seat 15, a second valve seat 17 formed on a valve plunger 16, and a valve body 18 seated on both valve seats 15 and 17 from the right side in the figure. and the second
As shown in the figure, the first valve seat 15 and the valve body 18 form a vacuum valve V which introduces negative pressure into the variable pressure chamber 6, and the second valve seat 17 and the valve body 18 form a vacuum valve V which introduces negative pressure into the variable pressure chamber 6. Each of them constitutes an atmospheric valve P for introducing atmospheric pressure into the variable pressure chamber 6.

The outer periphery of the first valve seat 15 is communicated with the constant pressure chamber 5 through a passage 19 formed in the valve body 7, and the constant pressure chamber 5 is connected to the constant pressure chamber 5 through a negative pressure introduction pipe 20 provided in the front shell 1, as shown in the figure. connected to a negative pressure source such as the engine's intake manifold. Further, an intermediate portion between the first valve seat 15 and the second valve seat 17 is communicated with the variable pressure chamber 6 via a flow path 21 formed in the valve body 7, and the second valve seat
The inner peripheral portion of the valve seat 17 is communicated with the atmosphere via a filter 22.

The valve plunger 16 is prevented from being pulled out from the valve body 7 by a key member 23, and an input shaft 2 is connected to the brake pedal (not shown).
4, and the distal end surface of the valve plunger 16 is disposed with one end surface facing the base end surface of the push rod 9 and the other end surface of the action disk 25.

However, as shown in FIGS. 2 and 3, the valve body 1
A plurality of radial slits are formed in the annular convex portion 18a formed at 8, and the slits are used as orifice passages 27. In the illustrated non-operating state, the valve body 1
8 is a spring 28 loaded between this and the input shaft 24.
is completely seated on the second valve seat 17 by
In this state, the seat portion 18b formed on the inner peripheral side of the annular protrusion 18a seats on the second valve seat 17 due to elastic deformation of the annular protrusion 18a, thereby blocking the orifice flow path 27.

In the above configuration, the atmospheric valve P is closed in the non-operating state shown in the figure, and in this state, the valve body 18 and the second
The seal portion 18b contacts the valve seat 17 to close the orifice passage 27, thereby completely blocking the atmosphere at that portion. Further, the vacuum valve V is opened and a required gap is formed between the valve body 18 and the first valve seat 15.

From this state, when the brake pedal (not shown) is depressed to move the input shaft 24 and valve plunger 16 to the left, the vacuum valve V closes and the constant pressure chamber 5
Then, the atmospheric valve P opens and communicates the atmosphere with the variable pressure chamber 6, so that atmospheric pressure is supplied into the variable pressure chamber 6, and the power is generated by the pressure difference before and after the power piston 3. The piston 3 is moved forward against the repulsive force of the return spring 10.

In this state, the reaction disk 25 is elastically deformed by the reaction force applied to the output shaft 9 and comes into contact with the valve plunger 16, similar to a conventionally known brake booster. The force is transmitted from the reaction disk 25 to the valve plunger 16 and then via the input shaft 24 to the brake pedal.

When the forward movement of the input shaft 24 is stopped from the brake operating state and the brake pedal force is kept constant, the atmosphere is introduced into the variable pressure chamber 6, and the advancing valve body 7 causes the tip surface of the annular convex portion 18a of the valve body 18 to 2 comes into contact with the valve seat 17, and as a result, the atmosphere and the variable pressure chamber 6 communicate only through the orifice passage 27 (for example, the reference numeral in FIG.
Q′ point).

If the brake pedal force is kept constant in this state, pressure fluid will be gradually supplied to the variable pressure chamber 6 via the orifice passage 27.
The valve body 7 is gradually advanced, whereby the annular convex portion 18a of the valve body is also gradually pressed against the second valve seat 17 by the elastic force of the spring 28 and is elastically deformed, so as to gradually close the orifice passage 27. Become. When the seal portion 18b of the valve body 18 finally seats on the second valve seat 17 and the atmospheric valve P closes, communication between the atmosphere and the variable pressure chamber 6 is completely cut off, and the advancement of the valve body 7 is stopped.

During this time, the output gradually increases from the above Q' point,
At point Q on characteristic curve A, orifice passage 27
is shut off and a servo balance state is achieved. If the brake pedal force is increased from this servo balance state, the atmospheric pressure P is opened, atmospheric air is introduced into the variable pressure chamber 6, and the output increases. At this time, the output will increase according to the characteristic curve A if the brake pedal force is increased very gradually and only the orifice passage 27 is opened. When the brake pedal force is increased to the extent that the brake is released, the output increases from point Q on the characteristic curve A to point U' on the characteristic curve A' at a ratio of 1:1 to the input, and then It begins to rise according to curve A'.

When the brake pedal force is relaxed, contrary to the above-described operation when the brake is applied, the atmosphere valve P is closed and the orifice passage 27 is closed, so the existence of the orifice passage 27 can be ignored.
Therefore, the output decreases according to characteristic curve A.

Next, even if the driver tries to stop the vehicle by maintaining the brake pedal force at point Q' on the characteristic curve A', and unconsciously loosens the brake pedal force just before the vehicle stops, Characteristic curve A
It simply drops from point Q above to point R.

Therefore, even if the driver unconsciously loosens the brake pedal force when trying to obtain the output of Q' on the characteristic curve A', the actual output will be close to the above Q'. Since R is obtained, the unconscious decrease in brake pedal force can be compensated for by the increase in the output, and thereby a brake feeling with a good brake feeling can be obtained.

In the above embodiment, a slit is formed in the valve body 18 to serve as the orifice passage 27.
In addition, for example, it is also possible to form a slit in the second valve seat 17 and use this as an orifice flow path.

[Effects of the invention] As described above, according to the invention, when the brake pedal force is unconsciously relaxed just before the vehicle stops, the output is lower than that obtained under the normal proportional relationship in the intermediate load state. Furthermore, since it is possible to obtain an effect equivalent to an increase in output, it is possible to obtain the effect that a good brake feeling with a good brake feeling can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing one embodiment of the present invention;
The figure is an enlarged sectional view of the main part of Figure 1, and Figure 3 is the valve body 1.
8 and FIG. 4 are characteristic diagrams obtained by the present invention. 5... constant pressure chamber, 6... variable pressure chamber, 7... valve body, 8... valve mechanism, 9... output shaft, 15... first valve seat, 16... valve plunger, 17... second valve seat , 18... Valve body, 18a... Annular convex portion, 18b
... Seat part, 24 ... Input shaft, 27 ... Orifice flow path.

Claims (1)

[Claims for Utility Model Registration] A valve plunger interlocked with an input shaft, a first valve seat formed on the valve body, a second valve seat formed on the valve plunger, and the first valve seat and the second valve seat. A brake booster comprising a valve body seated on the valve body and a second valve plunger on which the valve body is seated.
At least one of the valve seats is made of an elastic body, and an orifice passage is formed in which the flow path is blocked by elastic deformation of the elastic body when the valve body is seated on the second valve seat. Brake booster.