JPH0412853Y2 - - Google Patents

Description

[Detailed description of the invention] "Industrial application field" This invention relates to a reaction force mechanism of a brake booster.
More specifically, the present invention relates to a reaction force mechanism of a brake booster that transmits a brake reaction force applied to an output shaft to an input shaft via a reaction disk.

``Prior Art'' Conventionally, in the reaction force mechanism of a brake booster, a valve plunger and an output shaft base of the valve mechanism are respectively attached to the shaft of a valve body that is slidably disposed within a shell. In addition to being slidably fitted, there is a space between the output shaft and the valve plunger.
A reaction disk having a diameter larger than the tip end surface of the valve plunger is interposed so that the brake reaction force applied to the output shaft is transmitted to the valve plunger and the input shaft connected thereto via the reaction disk.

The reaction disk is compressed by the output shaft and the valve plunger when transmitting the brake reaction force applied to the output shaft to the valve plunger, and the reaction disk has a larger diameter than the tip surface of the valve plunger. Therefore, there is a problem that the contact portion of the reaction disk with the valve plunger is easily damaged.

In order to improve this drawback, a plate member harder than the reaction disk is provided between the reaction disk and the end surface of the valve plunger, so that the brake reaction force from the output shaft is transferred from the reaction disk to the valve plunger. A method has been proposed in which the signal is transmitted to a hard plate member and then to a valve plunger (Utility Model Application No. 138493/1983).

``Problem that the invention seeks to solve'' However, in a reaction force mechanism that includes a plate-like member that is harder than the reaction disk, it is necessary to prevent damage to the contact portion of the reaction disk and improve its durability. However, on the other hand, there is a problem in that the characteristics change significantly at low temperatures.

That is, in general, the hardness of elastic materials such as rubber increases as the temperature decreases, and in a reaction force mechanism that includes a plate-like member harder than the reaction disk, the hardness of an elastic material such as rubber increases at low temperatures. The hardness became too large and it became difficult to deform, thereby worsening the brake feeling.

"Means for Solving the Problem" The present invention was devised by focusing on the fact that the reaction disk is easily damaged along the contour of the tip surface of the valve plunger. In the force mechanism, the valve plunger is slidably fitted to the contact surface of the reaction disk with the valve plunger, which is harder than the reaction disk and follows the contour of the tip surface of the valve plunger. A ring-shaped member that can enter the hole of the valve body is provided, and the brake reaction force applied to the output shaft is transmitted to the valve plunger via the hard ring-shaped member and the reaction disk inside the ring-shaped member. be.

"Function" According to such a configuration, the hardness of the hard ring-shaped member can be freely set to a required hardness to prevent damage to the ring-shaped member itself and the reaction disk, and it is possible to prevent damage to the ring-shaped member itself and the reaction disk at low temperatures. Even if the hardness of the ring-shaped member increases, the brake reaction force applied to the output shaft is transmitted not only to the hard ring-shaped member but also to the valve plunger through the softer reaction disk inside the ring-shaped member. , it becomes possible to minimize the deterioration of the operating characteristics of the brake booster in low temperature conditions.

Therefore, according to the present invention, it is possible to avoid deterioration of the brake feeling at low temperatures while ensuring the high durability of the reaction disk obtained by providing the ring-shaped member.

"Example" The present invention will be explained below with reference to the illustrated example.
In FIG. 1, a power piston 2 is slidably provided in a shell 1 of a brake booster, and a diaphragm 3 is stretched on the back surface of the power piston 2. The interior of the shell 1 is divided into a constant pressure chamber 4 at the front and a variable pressure chamber 5 at the rear. A valve body 6 is integrally provided on the shaft portion of the power piston 2, and a valve mechanism 7 for switching the flow path is housed within the valve body 6.

The valve mechanism 7 has a first valve formed in the valve body 6.
A valve seat 10, a second valve seat 12 formed on the valve plunger 11, and a power piston 2 on both valve seats 10, 12.
A valve body 14 is provided which is seated from the rear side, that is, from the right side in FIG. 1, by the elastic force of a spring 13. The outside of the seat portion between the first valve seat 10 and the valve body 14 communicates with the constant pressure chamber 4 via a passage 15 formed in the valve body 6, and furthermore, the inside of the constant pressure chamber 4 is connected to a negative pressure chamber provided in the shell 1. It communicates with a negative pressure source such as an engine intake manifold via a pressure introduction pipe 16.

On the other hand, the intermediate portions of the seals between the first valve seat 10 and the valve body 14 and between the second valve seat 12 and the valve body 14 communicate with the variable pressure chamber 5 through a passage 17 formed in the valve body 6, and further The second valve seat 12 and the valve body 1
The inner side of the seat portion with 4 is communicated with the atmosphere via a filter 18.

Also, a valve plunger 1 constituting the valve mechanism 7
1 is connected to an input shaft 25 which is linked to a brake pedal (not shown), and the valve plunger 11 is linked to an output shaft 27 via a reaction disk 26. This output shaft 27 passes through the seal member 28 and projects to the outside of the shell 1, and is interlocked with a piston of a master cylinder (not shown). Furthermore, the power piston 2, valve body 6, etc. are normally held at the non-operating position shown in the figure by a return spring 29.

The tip of the valve plunger 11 is slidably fitted into a small diameter hole 6a formed in the shaft of the valve body 6, and is fitted into a large diameter hole 6b connected to the front of the small diameter hole 6a. The right end base 27a of the output shaft 27 is slidably fitted thereinto, and the reaction disk 26 is also fitted therein.

A protrusion 26a formed on the shaft of the end face of the reaction disk 26 on the valve plunger side is loosely fitted into the small diameter hole 6a, and a ring-shaped member 30 is applied around the protrusion 26a by vulcanization, adhesive, etc. It is attached by This ring-shaped member 30 is formed along the contour of the distal end surface 11a of the valve plunger 11, and its outer circumferential surface is in sliding contact with the inner circumferential surface of the small diameter hole 6a.

The ring-shaped member 30 is made of rubber or soft synthetic resin that has a harder hardness than the reaction disk 26. For example, the reaction disk 26 is made of a small hard rubber with a hardness of about Hs40 to 50, and the ring-shaped member 30 is made of a hard rubber with a hardness of about Hs65. It can be made of hard rubber with a hardness of about ~90. In addition, the protruding portion 2
The amount of protrusion of the ring 6a and the axial dimension of the ring-shaped member 30 are about 1 to 2 mm, and the thickness of the ring-shaped member 30, that is, the radial dimension is about 2 mm.

Furthermore, in this embodiment, the output shaft 27 is attached to the end surface of the reaction disk 26 on the output shaft 27 side.
A ring-shaped member 31 made of the same material as the ring-shaped member 30 is provided along the contour of the right end base 27a to prevent damage to the reaction disk 26 at that portion. However, this portion has a lower surface pressure than the portion provided with the ring-shaped member 30 and is less likely to be damaged, so the ring-shaped member 31 may be omitted if necessary.

In the above configuration, when the brake pedal (not shown) is depressed and the input shaft 25 and the valve plunger 11 move to the left, the valve body 14 moves toward the valve body 6.
The valve body 14 is seated on the first valve seat 10 of the valve plunger 11 to cut off communication between the variable pressure chamber 5 and the constant pressure chamber 4, and the valve body 14 is removed from the second valve seat of the valve plunger 11 to connect the atmosphere and the variable pressure chamber 5. communicate. As a result, atmospheric air is supplied into the variable pressure chamber 5, and the pressure difference between the front and rear sides of the power piston 2 causes the power piston 2 to move forward against the elastic force of the return spring 29, similar to a conventional brake booster. , a braking action is performed.

At this time, the brake reaction force applied to the output shaft 27 is transmitted from the output shaft 27 to the valve plunger 11 via the reaction disk 26 and the ring-shaped member 30, and further via the input shaft 25 to the brake pedal (not shown). is transmitted to.

In this reaction force transmission state, the ring-shaped member 30
has relatively sufficient hardness, so the ring-shaped member 30 will not get caught in the gap between the valve plunger 11 and the valve body 6 and be damaged. As in the case without a flexible reaction disk 26
It is possible to prevent the valve from getting caught in the gap between the valve plunger 11 and the valve body 6 and being damaged.

In addition, even if the hardness of the ring-shaped member 30 becomes higher than necessary due to low temperature,
Since the reaction disk 26 maintains a relatively flexible state and can transmit the brake reaction force from the output shaft 27 to the valve plunger 11 via the reaction disk 26, the brake boost in low temperature conditions is improved. Deterioration of the operating characteristics of the device can be minimized.

Figure 2 is a diagram showing the results of measuring how the operating characteristics at room temperature change at low temperatures for the brake booster having the above configuration.As a conventional device for comparison, the above reaction The protruding portion 26a of the disk 26 and the ring-shaped member 30 were made of a disk-shaped member made of the same material as the ring-shaped member 30.

What is indicated by the symbol A in FIG. 2 is the operating characteristic at room temperature, and there was no substantial difference in this between the device of the present invention and the conventional device. On the other hand, the symbol B indicates the operating characteristics of the device of the present invention at low temperatures, and the symbol C indicates the operating characteristics of the conventional device at low temperatures. This effectively prevents the operating characteristic B at low temperatures from changing significantly from the operating characteristic A at room temperature. In addition,
In the durability test, there was no substantial difference between the device of the present invention and the conventional device.

Next, FIG. 3 shows another embodiment of the present invention, in which the reaction disk 26 is formed in a concave portion 27b formed in the base 27a of the output shaft 27.
A ring-shaped member 30 is embedded in the right end surface of the reaction disk 26. In this case, when the brake booster is not in operation, the ring-shaped member 30 is located inside the large-diameter hole 6b, but when it is activated, it enters into the small-diameter hole 6a. A gap is formed to prevent that portion of the reaction disk 26 from being caught in the gap between the valve plunger 11 and the valve body 6.

It is clear that the same effects as those of the above-mentioned embodiments can be obtained in this embodiment as well. Note that the reaction disk having the configuration shown in this example is used as the first reaction disk.
It will also be obvious that the reaction disk having the structure shown in FIG. 1 can be applied to the embodiment shown in the figure, respectively.

"Effects of the Invention" As described above, according to the present invention, high durability of the reaction disk can be ensured by the ring-shaped member, and at the same time, the brake reaction force from the output shaft can be absorbed by the ring-shaped member. Since the pressure can be transmitted to the valve plunger through the inner reaction disk, it is possible to prevent brake feeling from deteriorating at low temperatures.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing one embodiment of the present invention;
The figure is a brake characteristic diagram showing test results for explaining the effects of the present invention, and FIG. 3 is a sectional view of a main part showing another embodiment of the present invention. 1... Ciel, 6... Valve body, 6a...
Small diameter hole, 6b... Large diameter hole, 7... Valve mechanism, 11...
...Valve plunger, 11a...Tip surface, 25...Input shaft, 26a...Protrusion, 26...Reaction disk, 27...Output shaft, 27a...Base, 3
0,31...Ring-shaped member.

Claims (1)

[Claims for Utility Model Registration] A valve plunger and a base of an output shaft that constitute a valve mechanism are slidably fitted into the shaft of a valve body that is slidably disposed within a shell, and the output thereof is A reaction disk having a diameter larger than the tip end surface of the valve plunger is interposed between the shaft and the valve plunger, and the brake reaction force applied to the output shaft is transferred to the valve plunger and the input connected thereto via the reaction disk. In the reaction force mechanism of the brake booster that is transmitted to the shaft, the contact surface of the reaction disk with the valve plunger is made of a material that is harder than the reaction disk, and that also follows the contour of the tip surface of the valve plunger, and A ring-shaped member that can enter into the hole of the valve body into which the valve plunger is slidably fitted is provided, and the brake reaction force applied to the output shaft is transmitted through the hard ring-shaped member and the reaction disk inside the ring-shaped member. A reaction force mechanism for a brake booster characterized by transmitting force to a valve plunger.