JPH035495Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a booster that applies an auxiliary force to the power piston that supports the diaphragm by means of a pressure difference applied to both sides of the diaphragm within the shell. .

[Conventional technology]

An example of a brake booster among this type of booster will be explained with reference to FIG. 1. 1 is a shell formed by connecting a front shell 2 and a rear shell 3, 4 is a power piston that moves forward and backward within the shell 1, and 5 , 6 are an input shaft and an output shaft connected to the power piston 4, respectively. 7 is a diaphragm, whose inner peripheral part 7a is supported by the power piston 4, and whose outer peripheral part 7b is held between the connecting parts of the shell 1 and divides the inside of the shell 1 into a negative pressure chamber 8 and an atmospheric pressure chamber 9. ing. Note that 10 is a negative pressure introduction pipe for introducing negative pressure into the negative pressure chamber 8.

Thus, a state in which negative pressure is introduced from the negative pressure introduction pipe 10 and no input is applied to the input shaft 5,
That is, when not in operation, the negative pressure is introduced from the negative pressure chamber 8 into the atmospheric chamber 9 via a valve mechanism in the power piston 4 (not shown), and the power piston 4 is held at the position shown in the diagram by the return spring 11. has been done. At this time, the diaphragm 7 has a folded portion 7c that extends from the outer peripheral edge of the back surface of the power piston 4 toward the front of the shell 1 (to the left in the figure) and is folded back.
A contact portion 7d is formed extending from the folded portion 7c to the outer circumferential portion 7b and making contact with the inner wall of the shell 1. From this state, input shaft 5
When the valve mechanism is activated, the communication between the negative pressure chamber 8 and the atmospheric pressure chamber 9 is cut off, and the atmosphere is introduced into the atmospheric pressure chamber 9. As a result, due to the pressure difference between the two chambers 8 and 9, A supporting force is applied to the power piston 4 to advance the output shaft 6.

[The problem that the idea aims to solve]

By the way, after the brake booster is installed in a vehicle, if the input shaft 5 is rapidly operated without introducing negative pressure during air bleeding from the brake piping, etc., the diaphragm 7 prevents the power piston 4 from moving forward. At times, due to the increase in the internal pressure of the negative pressure chamber 8, the power piston 4 tends to peel off from the back surface, and as shown in FIG.
When the power piston 4 subsequently returns rapidly, there is no risk that the deformed portion will be folded and caught in the back surface of the piston, resulting in a so-called rolling-in phenomenon. If such a curling phenomenon occurs, the output shaft 6 of the power piston 4 will be left in a protruding state with its shaft end pushing up the piston of the master cylinder (not shown) to which it is connected, and sufficient air bleeding will be required. I felt regret that I could not achieve this goal.

In view of the above points, it is an object of the present invention to provide a booster that does not cause the diaphragm curling phenomenon.

[Means to solve the problem]

The present invention includes a power piston that moves forward and backward within a shell, and a diaphragm that has an outer circumference attached to the shell and an inner circumference attached to the power piston, and when the power piston is not in operation, the diaphragm A diaphragm booster having a folded part extending from the outer circumferential edge of the rear surface of the power piston and folded back in an inverted manner between the outer circumferential part and the inner circumferential part, and a contact part that subsequently contacts the inner wall of the shell. An annular thick-walled portion having a thickness that is thicker and more uniform than the folded portion is formed at the contact portion of the diaphragm, and an annular thick-walled portion that is thicker than the folded portion and has a uniform thickness is formed at the contact portion of the diaphragm to the outer peripheral edge of the power piston. It is characterized by forming an annular thick part having a uniform thickness.

[Effect]

With the above configuration, the present invention allows the diaphragm to maintain its contact state with the inner wall of the shell even if the pressure in the negative pressure chamber increases during air bleeding work in the brake piping, and even if the folded part is bent. Since the elastic force for returning to the original shape is large, it is possible to prevent the curling phenomenon, and it is possible to provide a booster with good braking performance and excellent durability.

In addition, during normal brake operation, the folded part is difficult to sag and bulge due to the thick part formed at the contact part with the shell, so the effective diameter of the diaphragm does not change depending on the stroke amount and is stable. Output performance can be obtained.

〔Example〕

The present invention will be explained below with reference to the illustrated embodiments.
FIG. 3 shows the main parts of the device according to the present invention, and 12 is a thick wall portion formed at the portion of the diaphragm 7 that comes in contact with the inner wall of the front shell 2. This thick part 12 is
Folded portion 7 which is other part of diaphragm 7
It is thicker and has a more uniform thickness than C, etc., and has great rigidity, and extends and abuts against the inner wall of the shell 2, providing stronger resistance to bending deformation caused by external forces. possesses power.

Therefore, according to the above configuration, even if the power piston 4 is moved forward without introducing the negative pressure in the negative pressure chamber 8 during the air bleeding operation described above, the diaphragm 7 maintains the internal pressure on the negative pressure chamber 8 side. It maintains the state of contact with the inner wall of the shell 2 against the upward movement, and even if this thick part bends, it has a large elastic force to return to its original shape, so that the curved deformed part will not move as described above when the piston returns. It is possible to prevent such a phenomenon from occurring.

In addition, in the case of this configuration, since the thick portion 12 can maintain the state of contact with the shell 2 as described above,
The folded portion 7c hardly undergoes drooping, swelling, or deformation when the piston moves forward, and therefore always maintains stable high-output braking performance without causing any fluctuation in the effective working diameter of the power piston 4 during operation. You can expect it.

In FIG. 4, in addition to the thick wall portion 12 of the above structure, a thick wall portion 13 is also formed at the portion where the diaphragm contacts the back surface of the power piston 4. This thick portion 13 also has a uniform thickness like the thick portion 12 described above. In this way, by forming the thick parts 12 and 13 on both the contact part of the diaphragm 7 with the shell 1 and the contact part with the power piston 4, the diaphragm 7 deforms and is prevented from coming into contact with the shell 1 and the power piston 4. There is less risk of peeling, and even better effects can be achieved.

Note that the present invention is applicable not only to brake boosters but also to clutch boosters and the like.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide a booster that does not cause the diaphragm curling phenomenon, has better braking performance, and is more durable.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing an example of a brake booster, FIG. 2 is an explanatory diagram showing rolling deformation of the folded portion of the diaphragm, and FIG. 3 is an embodiment of the brake booster according to the present invention. FIG. 4 is an enlarged sectional view of the main part of only the diaphragm of the embodiment of the present invention. 1... Ciel, 4... Power Piston, 7...
Diaphragm, 7a...inner peripheral part, 7b...contact part, 7c...folded part, 12, 13...thick wall part.

Claims (1)

[Scope of utility model registration request] It includes a power piston that moves forward and backward within the shell, and a diaphragm whose outer circumference is attached to the shell and whose inner circumference is attached to the power piston, and when the power piston is not in operation, the diaphragm is connected to the outer circumference when the power piston is not in operation. In the booster, the power piston has a folded part that extends from the outer periphery of the rear surface of the power piston and is folded back, and a contact part that subsequently contacts the inner wall of the shell, the contact part of the diaphragm being in contact with the inner wall of the shell. The wall is thicker than the above folded part,
and an annular thick walled portion having a uniform thickness, and an annular thick walled portion that is thicker than the folded portion and has a uniform thickness at a portion of the diaphragm that contacts the outer peripheral edge of the power piston. A booster characterized by forming.