JPH0722366Y2 - Silence device for brake booster - Google Patents

Description

[Detailed description of the device] [Industrial applications]

The present invention relates to a muffling device that prevents noise caused by air flow when a brake booster is activated.

[Prior art]

Generally, a brake booster includes a power piston provided in a shell so as to move back and forth, a constant pressure chamber and a variable pressure chamber formed in front and rear of the power piston in a forward and backward direction, and a cylindrical valve body of the power piston shaft portion. A valve mechanism provided, an input shaft connected to a valve plunger that constitutes this valve mechanism, a pressure passage that communicates the valve mechanism with a pressure fluid source, and a constant pressure passage that communicates the valve mechanism with a constant pressure chamber, A variable pressure passage that connects the valve mechanism and the variable pressure chamber is provided, and the variable pressure passage further includes a gap between the inner peripheral surface of the cylindrical valve body and the outer peripheral surface of the valve plunger, and a radius of the valve body. And a radial passage that penetrates the inner peripheral surface of the valve body. In order to prevent noise caused by the flow of air during operation of the brake booster, it has been conventionally proposed to provide a muffling member such as an air filter in the radial passage that constitutes the variable pressure passage (special feature). (Kaisho 59-128040 publication).

[Problems to be solved by the device]

However, since the flow passage area of the radial passage cannot be increased so much, the provision of a relatively clogged sound deadening member having good sound absorption efficiency results in an increase in flow passage resistance, resulting in a delay in operation. There was no choice but to provide a coarse sound deadening member having a very low sound absorbing efficiency. In addition to this, since the sound deadening member provided in the radial passage is relatively separated from the valve mechanism serving as the sound source, the sound absorbing efficiency is also reduced in this respect.

[Means for Solving the Problems]

In view of such circumstances, the present invention provides the above-described conventional brake booster, in which a muffling member such as an air filter is arranged in a gap forming the variable pressure passage, and the muffling member opens the radial passage. The sound deadening member is attached to the outer peripheral surface of the valve plunger, and the sound deadening member can be moved forward and backward with respect to the opening of the radial passage integrally with the valve plunger.

[Action]

According to the above-mentioned configuration, the sound deadening member is displaced forward and backward together with the valve plunger, but the valve plunger is not advanced so much toward the opening of the radial passage during normal brake operation, so that the variable pressure passage Based on the air flow direction in, the amount by which the muffling member covers the opening of the radial passage can be largely maintained. On the other hand, during the sudden braking operation, the valve plunger is greatly advanced with respect to the opening of the radial passage, so that it is possible to reduce the amount of the silencing member covering the opening of the radial passage. As a result, since the amount of the muffling member covering the opening is large during normal brake operation, noise generated by the air flowing through the variable pressure passage can be effectively prevented, and the opening is covered during sudden braking. Since it is possible to reduce the amount of the sound deadening member, it is possible to reduce the flow path resistance due to the sound deadening member, thereby preventing the operation delay of the brake booster. Further, since the flow passage area of the gap forming the variable pressure passage can be made sufficiently larger than the flow passage area of the radial passage, a relatively clogged silencing member having good sound absorption efficiency is provided. However, the flow path resistance can be prevented from increasing, and the sound deadening member provided in the gap is adjacent to the valve mechanism that serves as a sound source. Therefore, the sound absorbing efficiency can be improved in this respect as well.

【Example】

An embodiment in which the present invention is applied to a tandem brake booster will be described below. In a sealed container formed of a front shell 1 and a rear shell 2, a front and rear front chambers 4 and a rear chamber 4 are formed by a center plate 3 provided at the center thereof. Room 5
, And a substantially cylindrical valve body 6 is slidably pierced through the shaft portions of the rear shell 2 and the center plate 3 by sealing members 7 and 8 while maintaining airtightness. The valve body 6 includes a front chamber 4 and a rear chamber 5
The front power piston 9 and the rear power piston 10 which are housed in and are connected to each other, and the front diaphragm 11 and the rear diaphragm 12 are respectively stretched on the back surfaces of the power pistons 9 and 10, and the diaphragm 1
The front chamber 4 and the rear chamber 5 are each divided into two chambers by 1 and 12 to form a total of four chambers A, B, C and D. The power pistons 9 and 10 and the valve body 6 are normally held by the return spring 13 in the non-actuated position in the figure. The valve mechanism 15 housed in the valve body 6 includes a first valve seat 16 formed in the valve body 6, a second valve seat 18 formed in a valve plunger 17 slidably fitted in the valve body 6,
Further, both valve seats 16 and 18 are provided with a valve body 20 which is seated from the right side of the drawing by the elastic force of a spring 19. The outside of the seat portion between the first valve seat 16 and the valve body 20 communicates with the constant pressure chambers A and C through a constant pressure passage formed by the axial passage 22 and the radial passage 23 formed in the valve body 6, Further, the constant pressure chamber A communicates with a negative pressure source such as an engine intake manifold via a negative pressure introducing pipe 24 provided in the front shell 1. On the other hand, the intermediate portion of each seal portion between the first valve seat 16 and the valve body 20 and the second valve seat 18 and the valve body 20 has an outer peripheral surface of the valve plunger 17 and a valve body that slidably fits the outer peripheral surface thereof. 6 is communicated with the variable pressure chamber D via a gap 26 between the inner circumferential surface of the valve 6 and the first variable pressure passage formed by the radial passage 27 formed in the valve body 6, and the variable pressure chamber D is connected to the shaft formed in the valve body 6. It always communicates with the variable pressure chamber B through the second variable pressure passage which is the directional passage 28. Furthermore, the second valve seat 18 and the valve body
The inside of the seat portion with 20 communicates with the atmosphere via a pressure passage provided with an air filter 29. In this embodiment, a silencer member 30 composed of an annular air filter is provided in the gap 26 between the outer peripheral surface of the valve plunger 17 and the inner peripheral surface of the valve body 6, and the silencer member 30 is provided.
Is fitted into an annular groove 17a formed on the outer peripheral surface of the valve plunger 17 and attached to the valve plunger 17. Further, the end of the valve plunger 17 which constitutes the valve mechanism 15 is connected to an input shaft 32 which is interlocked with a brake pedal (not shown), and the tip of the valve plunger 17 is pushed by a push rod 33
Is opposed to the end face of the reaction disc 34 provided in the large diameter portion on the right end of the. The tip of the push rod 33 is slidably projected from the shaft portion of the front shell 1 to the outside through a seal member 35, and is interlocked with a piston of a master cylinder (not shown). In the above configuration, when the brake pedal (not shown) is depressed and the input shaft 32 and the valve plunger 17 are moved leftward,
The valve body 20 is seated on the first valve seat 16 of the valve body 6 to shut off the communication between the variable pressure chambers B and D and the constant pressure chambers A and C, and the valve body 20 moves from the second valve seat 18 of the valve plunger 17 to It separates and makes the atmosphere communicate with the variable pressure chambers B and D. As a result, air is supplied into the variable pressure chambers B and D, and each power piston resists the resilience of the return spring 13 due to the pressure difference around the power pistons 9 and 10, as in the conventionally known brake booster. Then, the vehicle is advanced and the braking action is performed. At this time, the muffling member 30 is moved leftward integrally with the valve plunger 17, but during normal braking operation, the valve plunger 17 is moved toward the valve body 6 and thus the radial passage.
Since it does not move to the left so much to the opening of 27, the sound deadening member is based on the air flow direction in the variable pressure passage.
A large amount of 30 covering the opening of the radial passage 27 can be maintained. On the other hand, when the sudden braking is applied, the valve plunger 17 is moved largely to the left with respect to the opening of the radial passage 27, so that the muffling member 30 is also displaced to the left more than when the normal braking is applied. As a result, the amount by which the muffling member 30 covers the opening of the radial passage 27 decreases with reference to the flow direction of the air in the variable pressure passage. Thus, during normal brake operation, the amount of the muffling member 30 that covers the opening of the radial passage 27 can be maintained large, and noise generated by the air flowing through the variable pressure passage can be effectively prevented. At the time of sudden braking, by reducing the amount of the muffling member 30 that covers the opening of the radial passage 27, it is possible to reduce the flow path resistance by the muffling member 30 and prevent the operation delay of the brake booster. it can. When the depression of the brake pedal is released and the input shaft 32 and the valve plunger 17 are moved to the right from the above-described advanced state of the power pistons 9 and 10, the second valve seat 18 of the valve plunger 17 and the valve body 20 come into contact with each other. And disconnects the communication between the atmosphere and the variable pressure chambers B and D, and the valve body 20 separates from the first valve seat 16 of the valve body 6 to allow the variable pressure chambers B and D to communicate with the constant pressure chambers A and C. As a result, the air supplied into the variable pressure chambers B and D is discharged into the variable pressure chamber A, so that the power pistons 9 and 10 are
The pressure difference between the front and rear becomes small, and each power piston is returned to its original non-actuated position by the elastic force of the return spring 13, and the braking action is released. Also in this case, since the air discharged from the variable pressure chambers B and D to the constant pressure chamber A flows through the muffling member 30, the noise generated by the air flow is also reduced. In addition, the gap 26 has conventionally been formed by the valve mechanism 15 and the variable pressure chambers B and D.
Since the gap 26 is used as a part of the variable pressure passage that communicates with each other, the gap 26 can be used as it is as a space for providing the muffling member 30, and therefore it is not necessary to separately secure a space for providing the muffling member 30. Since the muffling member 30 is attached to the valve plunger 17, the muffling member 30 can be easily incorporated without complicating the assembly process of the brake booster. Further, since the gap 26 has a larger flow passage area than the radial passage 27 that connects the valve mechanism 15 and the variable pressure chamber D, the gap 26 is compared with the case where the silencing member 30 is provided in the radial passage 27. Therefore, even if a relatively clogged sound deadening member 30 having a high sound absorption efficiency is used, it is possible to easily secure a large space, and by making it large, it is possible to cause an operation delay in the brake booster. Can be prevented. Further, since the muffling member 30 can be disposed adjacent to the valve mechanism 15 serving as a sound source, compared with the case where the muffling member 30 is provided in the radial passage 27, the sound absorbing efficiency can be improved also in this respect. As the muffling member 30, a ring-shaped plate provided with a large number of through holes in addition to the air filter can be used.

[Effect of device]

As described above, in the present invention, since the sound deadening member is displaced forward and backward together with the valve plunger, noise can be effectively prevented during normal brake operation, and the sound deadening member can be effectively activated during sudden brake operation. It is possible to obtain an effect that the flow resistance due to is reduced and the operation delay of the brake booster can be prevented. Further, since the flow passage area of the gap forming the variable pressure passage can be made sufficiently larger than the flow passage area of the radial passage, it is necessary to provide a relatively clogged sound deadening member having good sound absorption efficiency. Also, since the flow path resistance can be prevented from increasing and the sound deadening member provided in the gap is adjacent to the valve mechanism that serves as a sound source, the effect of improving the sound absorbing efficiency can be obtained in this respect as well. . Furthermore, since the muffling member is attached to the valve plunger, the muffling member can be easily incorporated without complicating the assembly process of the brake booster.

[Brief description of drawings]

 FIG. 1 is a sectional view showing an embodiment of the present invention. 1, 2 ... Shell, 6 ... Valve body 9, 10 ... Power piston, 15 ... Valve mechanism 16 ... First valve seat, 17 ... Valve plunger 18 ... Second valve seat, 20 ... Valve body 26 …… Gap, 27 …… Radial passage 29 …… Air filter, 30 …… Muffling member 32 …… Input shaft, A, C …… Constant pressure chamber B, D …… Transformation chamber

Claims (1)

[Scope of utility model registration request] 1. A power piston provided in a shell so as to be movable back and forth, a constant pressure chamber and a variable pressure chamber formed in front and rear of the power piston, and a valve provided in a cylindrical valve body of the power piston shaft portion. Mechanism, an input shaft connected to a valve plunger forming the valve mechanism, a pressure passage communicating the valve mechanism with a pressure fluid source, a constant pressure passage communicating the valve mechanism with a constant pressure chamber, and the valve mechanism And a variable pressure passage communicating between the variable pressure chamber and the variable pressure chamber.The variable pressure passage is further provided in the valve body in a radial direction with a gap between the inner peripheral surface of the cylindrical valve body and the outer peripheral surface of the valve plunger. In the brake booster constituted by a radial passage that penetrates the inner peripheral surface of the valve body, a sound deadening member such as an air filter is provided in the gap, and the opening of the radial passage is formed by the sound deadening member. Cover The brake booster is characterized in that the sound deadening member is attached to the outer peripheral surface of the valve plunger so that the sound deadening member can be displaced forward and backward with respect to the opening of the radial passage integrally with the valve plunger. Device silencer.