JP2016141168A - Negative pressure type assistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a negative pressure type assistor including a front shell capable of improving strength and durability without impairing formability.SOLUTION: A negative pressure type assistor 1 includes: a booster shell 2 constituted of a front shell 8 and a rear shell 9; a diaphragm 13 for partitioning the inside of the booster shell 2 into a constant pressure chamber 18 and a change pressure chamber 19; the constant pressure chamber 18 formed between the front shell 8 and the diaphragm 13; and the change pressure chamber 19 formed between the rear shell 9 and the diaphragm 13. In the negative pressure type assistor 1, the front shell 8 includes a rib 11 which is bent toward the axial direction inside of the booster shell 2 and intermittently extends to a prescribed length in a circumferential direction, and a gradually changing section 22 in which a rib depth 21 to be an axial length at the axial direction inside in the rib is increased from an end 24 of the circumferential direction toward a center section 25.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a negative pressure booster employed in a vehicle brake device.

  One type of negative pressure booster (hereinafter referred to as a booster) is a valve body connected to a movable partition that divides a housing composed of a front shell and a rear shell into a front negative pressure chamber and a rear variable pressure chamber. Has a shaft hole, and in this shaft hole, a plunger that can move forward and backward in the axial direction with respect to the valve body and moves integrally with the input member, and according to the forward and backward movement of the plunger with respect to the valve body, A valve mechanism including a negative pressure valve that communicates and blocks between the negative pressure chamber and the variable pressure chamber and an atmospheric valve that communicates and blocks between the variable pressure chamber and the atmosphere is incorporated, and the front end of the plunger and the valve body A reaction member whose front end is engageable with the rear surface and an output member that is engaged with the front surface of the reaction member at the rear end and is movable in the axial direction with respect to the valve body are assembled. There is what is, for example, described in Patent Document 1 below.

JP2010-126039

  FIG. 4 shows the front shell described in Patent Document 1 described above. The front shell of FIG. 4 has ribs formed by bending the front shell toward the center side of the booster. FIG. 5 is a cross-sectional view of the rib taken along line BB in FIG. The rib extends so as to have a substantially arc shape in the circumferential direction of the front shell, and the axial length (hereinafter referred to as rib depth) which is the axial length is uniform between the end portions in the circumferential direction of the rib. Is formed. This rib contributes to improving the strength and durability of the front shell against the stress applied to the front shell that is generated when the negative pressure is introduced during the operation of the booster. Therefore, deformation of the front shell can be prevented by forming ribs on the front shell.

  However, the booster described in Patent Document 1 described above is formed to be uniform between the end portions in the circumferential direction of the rib. Paying attention to the amount of change in rib depth that changes toward the center in the circumferential direction of this rib, the rib depth from the wall surface (surface near the axis perpendicular to the axial direction of the rib booster) where the amount of change in rib depth is large Is formed (see FIG. 5) that is switched to a uniform bottom surface (a surface close to an axis parallel to the axial direction of the rib booster). In this inflection part, a curvature becomes large compared with another location. For this reason, for example, when the front shell is formed by press molding, the above-described inflection portion has a higher elongation rate than other portions. Here, the elongation rate indicates the degree of thinning of a specific location (value obtained by dividing the average thickness of the front shell by the thickness of the specific location). Thereby, in the inflection part mentioned above, since it will become thin plate from another location, we are anxious about the fall of the moldability, intensity | strength, and durability of a front shell. Further, in order to improve the strength and durability of the front shell, it has been studied to increase the rib depth. However, if the rib depth is set larger than the conventional one due to the thin plate of the inflection portion described above, the inflection portion of the rib may be damaged when the front shell is molded.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a booster shell constituted by a front shell and a rear shell, and is arranged between the front shell and the rear shell, and the booster shell is divided into a constant pressure chamber and a variable pressure chamber. A partitioning diaphragm and a constant pressure chamber are formed between the front shell and the diaphragm and connected to a negative pressure source, and a variable pressure chamber is formed between the rear shell and the diaphragm, and the constant pressure chamber or A negative pressure type booster connected to the atmosphere, wherein the front shell has a rib that is bent toward the inside in the axial direction of the booster shell and extends intermittently to a predetermined length in the circumferential direction, The rib depth, which is the axial length on the inner side in the axial direction of the rib, has a gradually changing portion that increases from the circumferential end toward the central portion.

  According to invention of Claim 1, it can reduce that the inflection part (refer FIG. 5) with a large curvature mentioned above (for example, R4 or less) is formed. Thereby, for example, when the front shell is press-molded, it is possible to reduce the above-described rib inflection part from being thinner than the other parts as compared to the case having the rib inflection part. Therefore, the strength and durability of the front shell can be improved. Furthermore, since the thin plate at the inflection portion of the rib described above can be reduced, the front shell can be formed by setting the rib depth larger than the conventional one. Thereby, the intensity | strength and durability of a front shell can be improved, without reducing a moldability.

  The invention according to claim 2 is characterized in that, in the invention according to claim 1, in the gradually changing portion, the rib depth increases smoothly from the end portion in the circumferential direction of the booster shell toward the center portion. And

  According to the invention of claim 2, since the rib depth increases smoothly from the end in the circumferential direction of the rib toward the center, it is more preferable to reduce the formation of the above-described inflection portion having a large curvature. it can. For this reason, for example, when press-molding the front shell, it is possible to further reduce the above-described inflection portion of the rib from being thinner than other portions. Thereby, the intensity | strength and durability of a front shell can be improved more.

It is sectional drawing which shows one Example of the negative pressure type booster which concerns on this invention. It is a front view of the front shell in FIG. It is sectional drawing along the AA of the front shell in FIG. It is a side view of the front shell of the conventional negative pressure type booster. It is sectional drawing along the BB line in FIG.

  Hereinafter, although embodiment of this invention is described concretely with FIGS. 1-3, this invention is not limited by the following embodiment, unless the meaning is exceeded.

  A negative pressure type booster (booster) 1 shown in FIGS. 1 and 2 is a tie rod type in which a master cylinder MC is fixed to a booster shell 2 by a tie rod bolt 3.

  The illustrated tie rod type negative pressure booster 1 includes a booster shell 2, a power piston 4, an input rod 5, an output rod 6, a return spring 7 for returning the power piston 4, and two tie rod bolts 3. It is configured in combination.

  The booster shell 2 includes a front shell 8 and a rear shell 9. The front shell 8 has a suction port 10 connected to the air supply manifold of the car engine. Furthermore, it has the rib 11 formed by curving the front shell 8 toward the inner side in the axial direction by press working.

  The power piston 4 is formed by combining a partition member 14 including a pressure plate 12 and a diaphragm 13 and a valve piston 17 having a negative pressure valve 15 and an atmospheric valve 16 therein.

  The negative pressure valve 15 is disposed in a passage that allows the constant pressure chamber 18 and the variable pressure chamber 19 to communicate with each other and opens and closes the passage. The atmospheric valve 16 is disposed in a passage that connects the variable pressure chamber 19 to the outside, and opens and closes the passage.

  The input rod 6 is inserted into the valve piston 17, and when the input rod 6 is pushed by a driver's brake operation, the valve body of the negative pressure valve 15 contacts the valve seat, the negative pressure valve 15 is closed, and the constant pressure chamber 18 is transformed. The communication of the chamber 19 is cut off.

  Further, when the input rod 6 is further pushed, the valve body of the atmospheric valve 16 is separated from the valve seat, the atmospheric valve 16 is opened, and the atmosphere flows into the variable pressure chamber 19.

  As a result, a pressure difference is generated between the constant pressure chamber 18 and the variable pressure chamber 19, and the power piston 4 receiving the pressure difference is propelled, and the thrust (force amplified according to the brake operation force) is transmitted via the output rod 6. The master cylinder MC is transmitted to the master cylinder MC. Such an operating mechanism is the same as that of a conventional negative pressure booster.

  The tie rod bolts 3 are inserted in an airtight manner into tie rod holes 20 provided in the front shell 8 and the rear shell 9 and tie rod holes 20 provided in the pressure plate.

  The tie rod bolt 3 is disposed so as to be parallel to a straight line passing through the center of the booster shell 2, and the master cylinder MC is fixed to the booster shell 2 using the tie rod bolt 3 as a fastener. The tie rod bolt 3 is also used to fix the booster shell 2 to the vehicle body of the vehicle in combination with a mounting bolt (not shown) for fixing the rear shell 9.

  In the negative pressure type booster 1 in the above-described embodiment, the rib 11 is formed in a substantially arc shape so as to extend intermittently by a predetermined length in the circumferential direction. The rib depth 21, which is the length in the axial direction of the booster shell 2, has a gradually changing portion 22 that gradually increases from the end 24 in the circumferential direction of the rib 11 toward the central portion 25.

  Further, the gradual change portion 22 has three stages (the first gradual change portion 22a having an angle of 0 ° to 3 ° formed by the angle formed between the surface parallel to the radial direction of the front shell 8 and the gradual change portion of the rib 11). The gradual change part 22 which becomes the 2nd gradual change part 22b of 3 degrees-6 degrees, and the 3rd gradual change part 22c of the angle 20 degrees-30 degrees formed is shown.

  In the negative pressure type booster 1 described above, when the inflection portion 23 (see FIG. 3) is switched from the wall surface 26 having a large change amount of the rib depth 21 shown in FIG. 5 to the bottom surface 27 having a small change amount of the rib depth. In contrast, for example, when the front shell is press-molded, the extension ratio of the inflection portion 23 in the rib 11 caused by pressing the front shell 8 can be reduced. Here, the elongation rate indicates the degree of thinning of a specific location (value obtained by dividing the average thickness of the front shell by the thickness of the specific location). Therefore, it is possible to reduce the thickness of the inflection portion 23 in the rib 11. Thereby, the intensity | strength and durability of the front shell 8 with respect to the stress which tries to deform | transform the front shell 8 which arises at the time of a booster action | operation can be improved. Further, since the above-described thin plate at the inflection portion 23 of the rib 11 can be reduced, the front shell 8 can be formed by setting the rib depth 21 to be larger than the conventional one. Thereby, the intensity | strength and durability of a front shell can be improved, without reducing a moldability.

  1 and 2, the rib depth 21 of the rib 11 is formed so as to gradually increase from the end portion 24 in the circumferential direction toward the center portion 25. The embodiment in which the angle formed by the three-stage (gradient changing portions 22a, 22b, 22c) is shown. However, as the rib depth 21 increases smoothly as it goes toward the central portion 25 in the circumferential direction of the rib 11, for example, the AA cross-sectional view in FIG. The gradual change portion 22 may also be formed. Thereby, it is possible to preferably avoid the formation of the inflection portion having a large curvature in the rib 11, and the reduction in thickness of the rib 11 can be reduced, so that the strength and durability of the front shell 8 can be improved.

  1 and 2 show an embodiment using a tie rod type booster as a preferred embodiment, but the embodiment can be similarly applied to other than the tie rod type booster, and the strength and durability of the front shell are improved. it can.

  1 and 2, as a preferred embodiment, an embodiment in which the rib 11 has a substantially arc shape extending in the circumferential direction is shown. However, the rib 11 is formed so as to have a non-arc shape in the circumferential direction. Also good.

DESCRIPTION OF SYMBOLS 1 Negative pressure type booster 2 Booster shell 3 Tie rod 4 Power piston 5 Input rod 6 Output rod 7 Return spring 8 Front shell 9 Rear shell 10 Suction port 11 Rib 12 Pressure plate 13 Diaphragm 14 Partition member 15 Negative pressure valve 16 Air pressure valve 17 Valve piston 18 Low pressure chamber 19 Transformer chamber 20 Tie rod hole 21 Rib depth 22 Gradual change portion 22a First gradual change portion 22b Second gradual change portion 22c Third gradual change portion 23 Bending portion 24 End portion 25 Central portion 26 Wall surface 27 Bottom surface MC Master cylinder

Claims (2)

A booster shell composed of a front shell and a rear shell;
A diaphragm that is disposed between the front shell and the rear shell and divides the booster shell into a constant pressure chamber and a variable pressure chamber;
The constant pressure chamber is formed between the front shell and the diaphragm and connected to a negative pressure source, and the variable pressure chamber is formed between the rear shell and the diaphragm. Or a negative pressure booster connected to the atmosphere,
The front shell has a rib that is bent toward the inner side in the axial direction of the booster shell and extends intermittently to a predetermined length in the circumferential direction, and is the axial length of the rib on the inner side in the axial direction A negative pressure booster having a gradually changing portion whose depth increases from the end in the circumferential direction toward the center. 2. The negative pressure booster according to claim 1, wherein the gradually changing portion has the rib depth that increases smoothly from the end portion in the circumferential direction of the booster shell toward the center portion.