KR102369886B1 - Diaphragm of brake booster for vehicle and manufacturing method of diaphragm - Google Patents

Abstract

The present invention relates to a diaphragm and bellopram for a brake booster, and a method for manufacturing the diaphragm and bellopram, and to a diaphragm for a brake booster dividing between a transformation chamber and a vacuum chamber in a brake booster and a method for manufacturing the diaphragm In particular, a circular insertion hole is formed in the center, an annular first protrusion connected to the valve body of the brake booster is formed on the inner circumferential surface of the circular insertion hole, and an annular second protrusion connected to the housing of the brake booster is formed on the outside A flexible expansion part is formed at a position connecting the first projection part and the second projection part, and when the plunger valve (input shaft) of the brake booster moves forward and backward, the expansion part is changed in the front-rear direction by air pressure, and the first projection is 2 Penetrating into the protrusion and moving in the front-rear direction, tearing and damage can be prevented, and poor airtightness can be prevented in advance.

Description

Diaphragm and bellopram of brake booster for electric vehicle and manufacturing method thereof

The present invention relates to a diaphragm for a brake booster that divides between a transformation chamber and a vacuum chamber in a brake booster, a bellopram and a method for manufacturing the diaphragm and bellofram, in particular, a circular insertion hole is formed in the center and the A first annular protrusion connected to the valve body of the brake booster is formed on the inner circumferential surface, and a second annular protrusion connected to the housing of the brake booster is formed on the outside, and flexible at a position connecting the first protrusion and the second protrusion One expansion part is formed, and when the plunger valve (input shaft) of the brake booster moves forward and backward, the expansion part is changed in the front-rear direction by air pressure, and the first protrusion penetrates into the second protrusion and moves in the front-rear direction to prevent tearing and damage. It relates to a diaphragm for a brake booster, a bellopram, and a method for manufacturing the diaphragm and bellopram that can be used to prevent airtightness in advance.

In general, a brake system of a vehicle acts to decelerate or stop a traveling vehicle, and a brake booster mounted on the brake system boosts the pedal effort of the driver when braking the vehicle. As a giving device, it can be largely divided into a vacuum booster, a hydraulic booster, and an electric booster.

In the case of hydraulic brakes configured to brake the vehicle using the hydraulic pressure generated by the operation of the brake pedal, the master cylinder that generates the hydraulic pressure forms a pressure difference between atmospheric pressure and vacuum according to the amount of depression of the brake pedal operated by the driver. It is operated by force applied from a booster, and this booster is configured integrally with a generator driven by the engine to amplify the brake pedal operation force and provide it to the master cylinder, or a mechanical type connected to the cab shaft of the engine intake manifold. There is a pump type (MVP, Mechanical Vacuum Pump) using a vacuum pump. However, in the case of a gasoline vehicle, a method using negative pressure generated by the reciprocating motion of the plunger valve in the engine intake manifold is mainly used.

This is a very economical method because it has less load than a pump type using a mechanical vacuum pump, and there is no need to separately attach an expensive mechanical pump.

The brake booster uses a plunger valve and a poppet valve to create a pressure difference between atmospheric pressure and vacuum inside while acting under the operating force of the brake pedal. When the relative distance difference within the valve body is formed, the atmospheric pressure introduced through the space according to the relative distance difference forms a pressure difference with the vacuum, and pushes the diaphragm, thereby operating the master cylinder with the boost power that adds atmospheric pressure to the pedal effort. .

Such a brake booster is a device that doubles the braking force applied to the input shaft by using the difference between vacuum and atmospheric pressure and transmits it to the output shaft. It includes a provided valve body 40 , and a diaphragm 20 having one end connected to the housing 10 and a center fixed to the valve body 40 . The inside of the housing 10 is divided into a transformation chamber (not shown) and a vacuum chamber (not shown) by a diaphragm 20 . In the brake booster, negative pressure is applied to the vacuum chamber (not shown) and atmospheric pressure is applied to the transformation chamber (not shown) according to the input through the input shaft.

The conventional diaphragm 20 is made of a rubber material, and is a device for transmitting boost force to the valve body 40 when atmospheric air flows into the transformation chamber (not shown) between the transformation chamber (not shown) and the vacuum chamber (not shown). .

In such a conventional diaphragm 20, a diaphragm plate 30 is provided on the diaphragm 20 to support and reinforce the diaphragm 20 at the same time.

Since there is a risk of deformation when only the diaphragm 20 formed of a rubber material is used, the diaphragm plate 30 is provided to transmit a uniform pressure without deformation, and is made of a flame-resistant steel plate material. However, there is a problem in that the weight is increased due to the diaphragm plate made of such a steel plate.

Also, the conventional diaphragm maintains airtightness and moves forward and backward (or up and down) by air pressure. The diaphragm may be damaged or torn.

When a small tear occurs in the conventional diaphragm, the tear is further increased in the process of repetitive operation of the diaphragm mounted on a vehicle, and the tensile strength is less than about 1,000 MPa, so the diaphragm does not have sufficient strength. When phosphorus is used and air pressure is increased, damage such as diaphragm burst occurs, so there is a problem that the replacement cycle of parts is short. As a result, in the end, the function of the booster cannot be performed, which leads to a safety accident and causes a loss of life.

Domestic Patent Publication No. 10-2006-0005231 Domestic Patent Publication No. 10-2014-0075943

The conventional diaphragm is made of the same material throughout, but when the plunger valve (input shaft) repeatedly moves forward and backward, the place where the load is concentrated is the central part of the diaphragm, so there is a problem that this part becomes weak.

The present invention was devised in consideration of the above problems, and in the diaphragm for a brake booster that divides the transformation chamber and the vacuum chamber in the brake booster, a circular insertion hole is formed in the center, and the valve body of the brake booster is formed on the inner circumferential surface of the circular insertion hole A first annular protrusion connected to is formed, a second annular protrusion connected to the housing of the brake booster is formed on the periphery, and a flexible expansion part (or tension part) is formed at a position connecting the first protrusion and the second protrusion. ) is formed, and when the plunger valve (input shaft) of the brake booster moves forward and backward, the first protrusion penetrates into the second protrusion and moves in the front-rear direction as the expansion part is changed in the front-rear direction by air pressure to prevent tearing and damage. Provided is a diaphragm and bellopram and a method for manufacturing the diaphragm and bellopram of a brake booster for electric vehicles that can prevent defective airtightness of the diaphragm in advance by increasing the fatigue life of the central weak area and increasing durability. has its purpose in

In order to achieve the above object, in the present invention, in the diaphragm and bellopram dividing the transformation chamber and the vacuum chamber in the brake booster, a circular insertion hole is formed in the center, and the inner circumferential surface of the circular insertion hole is connected to the valve body of the brake booster an annular first protrusion; a second annular protrusion connected to the housing of the brake booster on the outside and having a circular insertion hole formed in the center thereof; and a flexible expansion part formed at a position connecting the first protrusion and the second protrusion.

In addition, when the plunger valve (input shaft) of the brake booster moves forward and backward, the first protrusion penetrates into the second protrusion and moves in the front-rear direction while the expansion part is changed in the front-rear direction by air pressure to prevent tearing and damage. can

In addition, the expansion part has a structure that is folded or unfolded, and a first step (reinforcing rib) may be formed on the inner circumferential surface of the first protrusion, and a second step (reinforcement rib) may be formed on the inner circumferential surface of the second protrusion. .

In addition, the expansion part may be formed in a circular structure in which a polyester cloth is inserted between the upper and lower rubber sheets, and the polyester cloth may be configured to cross each other by forming two carbon fibers with a warp and a weft yarn.

On the other hand, the present invention relates to a method for manufacturing a diaphragm and a bellopram dividing a pressure chamber and a vacuum chamber in a brake booster, the first step of forming an annular first protrusion made of a rubber material and having a circular insertion hole formed on the inner circumferential surface ; a second step of forming an annular second protrusion made of a rubber material, a circular insertion hole formed on an inner circumferential surface, and relatively smaller than a diameter of the first protrusion; A third step of molding the expansion part in a circular structure in which a polyester cloth is inserted between the upper and lower rubber sheets; and after applying an adhesive to both ends of the expansion part, attaching both ends of the expansion part to the first protrusion and the second protrusion, and performing heat treatment and pressing (thermal sealing) at 100-120° C. to complete the product It provides a method for manufacturing a diaphragm of a brake booster for an electric vehicle comprising:

On the other hand, the present invention in the diaphragm and bellopram dividing the pressure chamber and the vacuum chamber in the brake booster, a circular insertion hole is formed in the center, the first annular protrusion connected to the valve body of the brake booster; A circular insertion hole is formed on the inner circumferential surface, the second annular protrusion is connected to the housing of the brake booster on the outside; and an annular expanded part formed between the first protrusion and the second protrusion, wherein the expanded part comprises a diaphragm of a brake booster for a train that is formed to protrude relatively than the first protrusion and the second protrusion. to provide.

An elastic body such as a spring may be disposed on a lower surface of the diaphragm and the bellopram to support the forward and backward movement of the diaphragm by air pressure.

For example, when the air escapes after descending of the diaphragm and the bellopram, the diaphragm and the bellofram may be restored to their original state by the restoring force of the elastic body.

As described above, according to the present invention, when the plunger valve (input shaft) of the brake booster moves forward and backward, the first protrusion penetrates into the second protrusion and moves in the front-rear direction while the expansion part is changed in the front-rear direction by air pressure to tear and Breakage can be prevented, and by increasing the fatigue life of the weak center part and increasing durability, it is possible to prevent airtightness of the diaphragm in advance.

1 is a cross-sectional view showing a conventional diaphragm for a brake booster;
2 is a perspective view illustrating a diaphragm and a bellopram of the brake booster for an electric vehicle according to the first embodiment of the present invention;
3 is a front view of FIG. 2
Fig. 4 is a left side view of Fig. 3;
5 is a longitudinal cross-sectional view of FIG.
Figure 6 is a longitudinal cross-sectional view showing the variable in the front-rear direction of the expansion part of Figure 2;
7 is a longitudinal cross-sectional view showing a diaphragm and a bellopram of a brake booster for an electric vehicle according to a modified example of the present invention;
8 is a flowchart illustrating a method for manufacturing a diaphragm and a bellopram of a brake booster for an electric vehicle according to the first embodiment of the present invention;
9 is a perspective view illustrating a diaphragm and a bellopram of a brake booster for an electric vehicle according to a second embodiment of the present invention;
10 is a longitudinal cross-sectional view of FIG.

Hereinafter, a diaphragm and a bellopram of the brake booster for an electric vehicle of the present invention will be described with reference to the accompanying drawings.

The brake booster of the present invention is a device that doubles the braking force applied to the input shaft by using the difference between vacuum and atmospheric pressure and transmits it to the output shaft. The brake booster includes a housing 10 and a valve body 40 provided inside the housing 10 and diaphragms 100 and 200 having one end connected to the housing 10 and a center fixed to the valve body 40 . The diaphragms 100 and 200 serve to divide between the transformer chamber and the vacuum chamber in the brake booster. The configuration of the brake booster will be referred to FIG. 1 .

The inside of the housing 10 is divided into a transformation chamber (not shown) and a vacuum chamber (not shown) by a diaphragm and a bellopram 20 . In the brake booster, negative pressure is applied to the vacuum chamber (not shown) and atmospheric pressure is applied to the transformation chamber (not shown) according to an input through the input shaft (plunger valve).

The diaphragm and bellopram 100 show the first embodiment of the present invention, and the diaphragm and bellopram 200 show the second embodiment.

First, FIG. 2 is a perspective view illustrating a diaphragm and a bellopram of a brake booster for an electric vehicle according to a first embodiment of the present invention, FIG. 3 is a front view of FIG. 2, FIG. 4 is a left side view of FIG. In FIG. 3, a longitudinal sectional view showing the variable in the front-rear direction of the expansion part, FIG. 6 is a longitudinal sectional view showing the diaphragm and bellopram of the brake booster for an electric vehicle according to a modified example of the present invention.

Referring to the drawings above, in the diaphragm and bellopram 100 according to the first embodiment of the present invention, a circular insertion hole 101 is formed in the center, and the valve body of the brake booster is formed on the inner circumferential surface of the circular insertion hole 101 . An annular first protrusion 110 connected to; a second protrusion 120 of an annular shape connected to the housing of the brake booster on the outside and having a circular insertion hole 102 formed in the center thereof; and a flexible expansion part 130 formed at a position connecting the first protrusion 110 and the second protrusion 120 ; includes

In addition, in the diaphragm and bellopram 100 according to the first embodiment of the present invention, when the plunger valve of the brake booster moves forward and backward, the expansion unit 130 is changed in the front-rear direction by air pressure, and the first protrusion As the 110 penetrates into the second protrusion 120 and moves in the front-rear direction, tearing and damage can be prevented.

That is, in the brake booster, negative pressure acts in the vacuum chamber (not shown) according to an input through the plunger valve (input shaft or piston) and atmospheric pressure acts in the transformation chamber (not shown), so the expansion unit 130 according to the pressure difference ) can effectively prevent tearing and breakage of the diaphragm as it moves in the upper or lower direction.

In addition, the expansion part 130 has a structure that can be folded or unfolded and made of an elastic member, a first stepped (reinforcing rib) 111 is formed on an inner circumferential surface of the first protrusion 110 , and the second protrusion part A second step (reinforcing rib) 121 may be formed on the inner circumferential surface of the 120 .

The first step (reinforcing rib) 111 and the second step (reinforcing rib) 121 increase the rigidity of the first protrusion 110 and the second protrusion 120 to extend the service life of the diaphragm. there is.

In addition, the thickness t of the expansion unit 130 may be formed to be 1-3 mm, and the expansion unit 130 serves to transmit boosting force when the atmosphere is introduced into the transformation chamber between the pressure chamber and the vacuum chamber of the housing. do.

The expansion part 130 is formed in a circular structure in which a polyester cloth 133 is inserted between the upper and lower rubber sheets 131 and 132, and the polyester cloth 133 is composed of two carbon fibers with warp and weft yarns to cross each other. can be configured to

It is preferable that the polyester fabric 133 has different weaving directions so as to withstand the stress not only in the horizontal and vertical directions, but also in the diagonal direction. In addition, even if the weaving direction is the same, the same or similar effect as that in which the weaving direction is different can be achieved by cutting and arranging the diaphragm so that the weaving direction is inclined at 45°.

In addition, an annular reinforcing carbon fiber 140 may be provided in the first protrusion 110 and the second protrusion 120 of the diaphragm 100 (see FIG. 6 ).

The reinforcing carbon fiber 140 may be formed in the first protrusion 110 and the second protrusion 120 in an insert manner. It can solve the problem that parts replacement cycle is short due to damage such as diaphragm bursting during repeated use and air pressure increase.

In addition, an annular reinforcing carbon fiber 140 is provided in the first protrusion 110 and the second protrusion 120 to solve the conventional problem that the diaphragm is damaged during long-term operation when air pressure exceeding 3 bar is injected can do.

The reinforcing carbon fiber 140 of the present invention may have a tensile strength of 3,500 to 7,000 MPa, and a tensile modulus of 200 to 700 MPa.

The diaphragm using the reinforcing carbon fiber 140 of the present invention can operate stably even at 5 to 6 bar.

In addition, by forming a wrinkle (bellows) 150 on the surface of the inflating part 130, when the plunger valve (input shaft) of the brake booster moves forward and backward, the inflation part 130 is variable in the front-rear direction by air pressure. In this case, the expansion part 130 can be easily changed in the front-rear direction, thereby more effectively preventing tearing and damage (see FIG. 6 ).

In addition, in the expansion part 130 of the diaphragm, a polyester cloth 133 is inserted between the upper and lower rubber sheets 131 and 132 to have a circular structure, and the polyester cloth 133 is subjected to insert molding. It can be molded by embedding between the upper and lower rubber sheets 131 and 132 by the

The expansion part 130, a first flange 131a is formed on one side and a second flange 132a is formed on the other side, so that it can be joined to the first projection part 100 and the second projection part 120, respectively. .

The second flange 132a is formed with a rounding portion R, thereby increasing elasticity and durability of the inflatable portion 130, further enhancing the effect of preventing tearing and damage, and preventing defective airtightness of the diaphragm in advance. can do.

The shape of the diaphragm and bellopram of the present invention can be adopted as a trapezoid, and the reason for this is as follows.

(a) In a brake booster (or vacuum on/off valve) having a diaphragm, the outer diameter of the outer peripheral surface of the plunger valve (input shaft) is smaller than the inner diameter of the cylinder by a portion having a predetermined interval, and the expansion part of the diaphragm (130) The plunger valve can be sufficiently stretched to the position of top dead center with driving of the plunger valve.

(b) In the brake booster (or vacuum on/off valve), the expansion part 130 is made of a stretchable material (flexible material), and furthermore, a wrinkle part 150 is formed so as to be inclined in the axial direction of the plunger valve (input shaft). In the brake booster, negative pressure acts in the vacuum chamber (not shown) according to the input through the input shaft (plunger valve), and atmospheric pressure acts in the transformation chamber (not shown), so the expansion unit 130 according to the pressure difference. Tear and breakage of the diaphragm can be more effectively prevented as the diaphragm moves upward or downward.

Meanwhile, FIG. 7 is a flowchart illustrating a method for manufacturing a diaphragm and a bellopram of a brake booster for an electric vehicle according to the first embodiment of the present invention.

Referring to the above drawings, the present invention relates to a method for manufacturing a diaphragm and a bellopram dividing a pressure chamber and a vacuum chamber in a brake booster, the first annular shape made of a rubber material and having a circular insertion hole 101 formed on the inner circumferential surface. A first step of forming the protrusion 101 (S10); A second step (S20) of forming a second protrusion 120 of an annular shape made of a rubber material, a circular insertion hole 102 is formed on the inner circumferential surface, and relatively smaller than the diameter of the first protrusion 110; A third step (S30) of molding the inflatable part in a circular structure in which the polyester cloth 133 is inserted between the upper and lower rubber sheets 131 and 132 (S30); And after applying an adhesive (not shown) to both ends of the expansion part 130, the both ends of the expansion part 130 are adhered to the first protrusion 110 and the second protrusion 120, and 100-120° C. A fourth step (S40) of completing the product by heat treatment and pressing (thermal fusion); It provides a method for manufacturing a diaphragm of a brake booster for an electric vehicle comprising a.

That is, in the first step (S10), a raw rubber material is injected into the mold, and the annular first protrusion 101 having a circular insertion hole 101 formed on the inner circumferential surface is molded.

In the second step (S20), a rubber raw material is injected into the mold, a circular insertion hole 102 is formed on the inner circumferential surface, and the second protrusion 120 of an annular shape is relatively smaller than the diameter of the first protrusion 110 . ) is molded.

In the third step (S30), the expansion part is molded into a circular structure in which the polyester cloth 133 is inserted between the upper and lower rubber sheets 131 and 132 .

In the fourth step (S40), after an adhesive (not shown) is applied to both ends of the expandable part 130 , both ends of the expandable part 130 are applied to both ends of the first protrusion 110 and the second protrusion 120 . The product is finished by heat treatment at 100-120℃ and pressing (thermal fusion).

The expansion part 130, a first flange 131a is formed on one side and a second flange 132a is formed on the other side, and is joined to the first projection part 100 and the second projection part 120, respectively.

In addition, the expansion part 130 may be formed of a synthetic resin having elasticity, for example, rubber (TPE, SBR), and is connected to the second protrusion 120 connected to the housing of the brake booster and the valve body of the brake booster. It is provided between the first protrusions 110 that become

In addition, the diaphragm and bellopram of the present invention may be made of a PET material (polyethylene terephthalate), and the PET material is a polyester resin having a relatively high density and is a crystalline or amorphous thermoplastic plastic. The characteristics of amorphous PET are high transparency, and crystalline PET has high hardness, rigidity and strength, and excellent sliding and abrasion resistance (compared to POM). Due to their excellent dimensional stability, PET materials are well suited for complex parts and applications where dimensional precision and surface quality are demanding.

The diaphragm of the present invention uses PET 90 denier grade, NBR 32 kg, carbon 25 kg, oil 72 kg, is mixed and manufactured, and is adhered to rubber using Cheonong adhesive, and then heat-treated (100-120° C.) It can be manufactured with a molding press.

Through the above process, the diaphragm of the present invention can be reinforced with a material with reinforced strength and rigidity to reinforce the portion where repeated loads are applied.

Meanwhile, FIG. 8 is a perspective view illustrating a diaphragm and a bellopram of a brake booster for an electric vehicle according to a second embodiment of the present invention, and FIG. 9 is a longitudinal cross-sectional view of FIG. 8 .

Referring to the drawing above, in the diaphragm, bellopram 200 according to the second embodiment of the present invention, a circular insertion hole 201 is formed in the center, and an annular first protrusion 210 is connected to the valve body of the brake booster. ); A circular insertion hole 202 is formed on the inner circumferential surface, the second annular protrusion 220 is connected to the housing of the brake booster on the outside; and an annular expanded part 230 formed between the first protrusion 210 and the second protrusion 220 , wherein the expanded part 130 includes the first protrusion 210 and the second protrusion 220 . It is formed to protrude relatively than the protrusion 220 .

In the diaphragm and bellopram 200 according to the second embodiment of the present invention, when the plunger valve (input shaft) of the brake booster moves forward and backward, the expansion part 230 is changed in the front-rear direction by air pressure and is torn and damaged This can be prevented.

That is, in the brake booster, negative pressure acts in the vacuum chamber (not shown) according to the input through the plunger valve (input shaft), and atmospheric pressure acts in the transformation chamber (not shown), so the expansion unit 130 moves according to the pressure difference. As it is pressed or elastically restored, it is possible to effectively prevent tearing and breakage of the diaphragm.

As described above, according to the present invention, when the plunger valve (input shaft) of the brake booster moves forward and backward, the first protrusion penetrates into the second protrusion and moves in the front-rear direction while the expansion part is changed in the front-rear direction by air pressure to tear and Breakage can be prevented, and by increasing the fatigue life of the weak center part and increasing durability, it is possible to prevent airtightness of the diaphragm in advance.

As the embodiments of the present invention have been described in detail, the scope of the present invention is not limited to the above-described embodiments, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims Also included in the scope of the present invention.

In this embodiment, the transformer chamber and the vacuum chamber of the brake booster correspond to known common configurations, and thus are not specifically illustrated or described, and certain features presented in the drawings are enlarged, reduced, or simplified for ease of explanation, and the drawings and their Components are not necessarily drawn to scale. However, those skilled in the art will readily understand these details.

Terms including ordinal numbers such as 'first' and 'second' may be used to describe various elements, but the elements are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. In addition, expressions such as up and down are arbitrarily defined for convenience of explanation based on what is shown in the drawings, and may be replaced with before and after.

In addition, although only the diaphragm of the brake booster for an electric vehicle is illustrated and described in this embodiment, the technology of the present invention is equally applicable to not only the diaphragm but also the bellofram. A bellofram is one of the transducers for the process that converts pressure into displacement, and has the advantages of both a bellows and a diaphragm.

The terms or words used in the present specification and claims described above should not be construed as being limited to conventional or dictionary meanings, and the inventor should appropriately use the concept of terms to describe his invention in the best way. Based on the principle that it can be defined, it should be interpreted as meaning and concept consistent with the technical idea of the present invention.

Therefore, the embodiments described in this specification and the configurations shown in the drawings are only the most preferred embodiment of the present invention, and do not represent all of the technical spirit of the present invention. It should be understood that there may be equivalents and variations.

100: diaphragm, bellopram according to the first embodiment of the present invention
101: circular insertion hole
102: circular insertion hole
110: first protrusion
111: first step (reinforcing rib)
120: second protrusion
121: second step (reinforcement rib)
130: expansion part
131, 132: upper and lower rubber sheets
133: polyester cloth
140: reinforcing carbon fiber
150: pleats (bellows)
200: diaphragm and bellopram according to the second embodiment of the present invention
210: first protrusion
220: second protrusion
230: expansion part

Claims (7)

In the diaphragm dividing the transformer chamber and the vacuum chamber in the brake booster,
The circular insertion hole 101 is formed in the center, the circular first protrusion 110 is connected to the valve body of the brake booster on the inner peripheral surface of the circular insertion hole 101;
a second protrusion 120 of an annular shape which is connected to the housing of the brake booster on the outside and a circular insertion hole 102 is formed in the center; and
It includes; a flexible expansion part 130 formed at a position connecting the first protrusion 110 and the second protrusion 120 ,
When the input shaft (plunger valve) of the brake booster moves forward and backward, the first protrusion 110 penetrates into the second protrusion 120 and moves in the front-rear direction while the expansion part 130 is changed in the front-rear direction by air pressure. to prevent tearing and breakage,
The expansion part 130 has a structure that is folded or unfolded, and is made of an elastic member, a first step (reinforcing rib) 111 is formed on an inner circumferential surface of the first protrusion 110 , and an inner circumferential surface of the second protrusion 120 . A second step (reinforcing rib) 121 is formed on the
The expansion unit 130 is formed in a circular structure in which a polyester cloth 133 is inserted between the upper and lower rubber sheets 131 and 132, and the polyester cloth 133 is composed of two carbon fibers with warp and weft yarns to cross each other. composed,
A reinforcing carbon fiber 140 is installed in the first protrusion 110 and the second protrusion 120 , and a wrinkle part (bellows) 150 is formed on the surface of the inflatable part 130 ,
The thickness (t) of the expansion part 130 is formed to be 1-3 mm, so that when the atmosphere is introduced into the transformation chamber between the transformation chamber and the vacuum chamber of the housing, the boosting force is transmitted,
The polyester fabric 133 has different weaving directions so that it can withstand stress not only in the horizontal and vertical directions but also in the diagonal direction, and even if the weaving directions are the same, the weaving direction is cut so that the weaving direction is inclined at 45° when the diaphragm is manufactured (裁斷) and arrangement have the same effect as different weaving directions,
The reinforcing carbon fiber 140 has a tensile strength of 3,500 to 7,000 MPa and a tensile modulus of 200 to 700 MPa, and the air pressure is 5 to 6 bar, even if the diaphragm is to work undamaged,
The polyester cloth 133 is molded by embedding between the upper and lower rubber sheets 131 and 132 by insert molding,
The expansion part 130, a first flange 131a is formed on one side and a second flange 132a is formed on the other side, and is joined to the first protrusion 100 and the second protrusion 120, respectively,
The second flange (132a) is formed with a rounding portion (R), it is possible to increase the elasticity and durability of the expansion portion 130,
The diaphragm has a trapezoidal shape, so that, in the brake booster having the diaphragm, the outer circumference of the plunger valve is smaller than the inner diameter of the cylinder by a portion having a predetermined interval, and the expansion part of the diaphragm 130 can be sufficiently stretched with driving of the plunger valve to the position of top dead center of the plunger valve, and in the brake booster, while the expansion part 130 is made of a stretchable material, and also a wrinkle part 150 to form an inclined surface in the axial direction of the plunger valve (input shaft) to form a negative pressure in the vacuum chamber (not shown) according to the pressure through the plunger valve in the brake booster, and atmospheric pressure in the transformation chamber (not shown) As this works, the diaphragm of the brake booster for a train, characterized in that it is possible to prevent tearing and damage of the diaphragm as the expansion part 130 moves in the upper or lower direction according to the pressure difference.
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