JP3759451B2 - Shell structure of negative pressure booster - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a shell structure of a negative pressure booster, and in particular, a front shell half constituting a booster shell in cooperation with a rear shell half, a cylindrical portion having a rear end coupled to the rear shell half, Basically, a pair of fastening points are arranged on an imaginary straight line perpendicular to the axis of the master cylinder that is formed so as to have a smaller diameter toward the front and that is continuous with the front end of the cylindrical portion and has a flange at the rear. And a flat mounting portion provided at a front end of the end wall portion so as to be fastened to the flange.
[0002]
[Prior art]
Conventionally, such a shell structure is already known, for example, in Japanese Patent Application Laid-Open No. 7-205798 and Japanese Utility Model Application Laid-Open No. 56-152760.
[0003]
[Problems to be solved by the invention]
During operation of the negative pressure booster and master cylinder, the hydraulic pressure generated in the hydraulic chamber of the master cylinder acts as a load that causes the end wall to bulge forward on the end wall of the front shell half In order to sufficiently withstand the load, in the above-described conventional device, the reinforcing member is fixed to the inner surface of the end wall portion. However, if the reinforcing member is used unnecessarily, the negative pressure booster increases in size or the negative pressure booster increases in weight.
[0004]
By the way, in order to sufficiently increase the rigidity of the end wall portion of the front shell half, it is desirable to form the end wall portion so as to linearly connect the outer edge of the attachment portion and the front end edge of the cylindrical portion. However, the load acting on the end wall from the master cylinder side is the largest on the straight line where the flange and the fastening part are fastened, that is, on the virtual straight line perpendicular to the axis of the master cylinder. When the end wall portion is formed over the entire circumference so as to linearly connect the outer edge of the portion and the front end edge of the cylindrical portion, stress concentration occurs on the end wall portion and the connecting portion of the cylindrical portion in the vicinity of the virtual line.
[0005]
The present invention has been made in view of such circumstances, and is a negative pressure booster designed to increase the overall strength of the end wall portion of the front shell half while reducing the weight without using unnecessary reinforcing members. An object of the present invention is to provide a shell structure.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 is characterized in that a front shell half constituting a booster shell in cooperation with a rear shell half is formed of a cylindrical portion whose rear end is coupled to the rear shell half. Basically, a pair of fastenings arranged on an imaginary straight line perpendicular to the axis of the master cylinder, which is formed so as to have a smaller diameter toward the front and which is continuous with the front end of the cylindrical portion, and a flange at the rear portion In a negative pressure booster shell structure comprising a flat mounting portion provided at the front end of the end wall portion so as to be fastened to the flange at a location, a load is applied to the end wall portion by the operation of the negative pressure booster and the master cylinder. In order to increase the overall strength of the end wall portion by sufficiently bending the end wall portion on the virtual straight line to relieve stress and obtaining sufficient rigidity in a portion orthogonal to the virtual straight line. to, the Cross-sectional shape of the end wall portion along a plane passing through the axis of the front shell half is orthogonal to the virtual straight line, Ru is formed in the mounting portion of the outer edge and the cylindrical portion straight linear connects between the front edge of the together with the cross-sectional shape of the end wall portion along a plane passing through the axis of the virtual straight line and the front shell half is formed of a plurality of straight lines forming an angle to each other of the mounting portion outer edge and the cylindrical portion It is formed so as to connect the front end edges.
[0007]
According to such a configuration, on the imaginary straight line where the load acting on the end wall portion by the generated hydraulic pressure of the master cylinder is the largest, that is, on the imaginary straight line where the fastening portion of the flange and the mounting portion is arranged, a plurality of angles are formed. Since the end wall portion is formed so as to connect the outer edge of the mounting portion and the front end edge of the cylindrical portion, the end wall portion is sufficiently bent on the virtual straight line to relieve stress. As a result, stress concentration can be prevented from occurring at the connecting portion between the end wall portion and the cylindrical portion. On the other hand, in the portion perpendicular to the imaginary straight line, it is possible to obtain a sufficient rigidity by forming the end wall so as to connect between the front edge of the outer edge and the cylindrical portion of the mounting portion in a straight line shape. Therefore, the strength of the entire end wall portion can be improved while reducing the weight of the end wall portion without using a reinforcing member more than necessary.
[0008]
According to a second aspect of the present invention, in addition to the above-described configuration of the first aspect, the large-diameter end portion of the end wall portion includes a plurality of concave portions recessed in an arc shape on the radially inner side of the front shell half. , Formed at a distance from each other in the circumferential direction at a position that avoids a plane passing through the axis of the virtual straight line and the front shell half and a plane orthogonal to the virtual straight line and passing through the axis of the front shell half And a negative pressure introducing pipe is disposed in one of the recesses.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on one embodiment of the present invention shown in the accompanying drawings.
[0010]
1 to 3 show an embodiment of the present invention. FIG. 1 is a longitudinal side view of a negative pressure booster, FIG. 2 is a front view of a front shell half, and FIG. It is line sectional drawing.
[0011]
First, in FIG. 1, the booster shell 5 of the negative pressure booster B is constituted by connecting a front shell half 6 and a rear shell half 7 to each other. It is accommodated so that it can reciprocate.
[0012]
A diaphragm 9 is polymerized on the rear surface of the booster piston 8, and an outer peripheral bead 9 a of the diaphragm 9 is bonded to the abutting portions of the front and rear shell halves 6 and 7.
[0013]
The booster shell 5 is partitioned by a booster piston 8 and a diaphragm 9 into a negative pressure chamber 10 on the front side that faces the front surface of the booster shell 5 and a working chamber 11 that faces the rear surface of the diaphragm 9.
[0014]
A synthetic resin valve cylinder 12 is coupled to the central portions of the booster piston 8 and the diaphragm 9. The valve cylinder 12 is slidably supported via a bearing member 52 on a support cylinder portion 7a projecting from the center of the rear wall of the rear shell half body 7, and the bearing member 52 is engaged with the support cylinder portion 7a. It is held between the locking ring 13 to be stopped and the support cylinder portion 7a. A negative pressure introduction pipe 51 is connected to the front wall of the booster shell 5, and the negative pressure chamber 10 is connected to a negative pressure source (not shown) (for example, an intake manifold of the engine) via the negative pressure introduction pipe 51. .
[0015]
The valve cylinder 12 is switched between the valve piston 14, a part of the input rod 15 connected to the valve piston 14, and the working chamber 11 in communication with the negative pressure chamber 10 and the atmosphere according to the back-and-forth movement of the input rod 15. And the control valve 16 to be accommodated.
[0016]
The valve piston 14 is slidably fitted into a guide hole 17 provided in the valve cylinder 12, and a reaction force piston 19 is connected to the front end of the valve piston 14 via a neck portion 18. The input rod 15 that is connected to the brake pedal 20 and moves back and forth has a spherical portion at the tip, and the spherical portion is connected to the rear portion of the valve piston 14 so as to swing.
[0017]
The control valve 16 includes a negative pressure introduction valve seat 21, an atmosphere introduction valve seat 22, a valve body 23, and a valve spring 24. The atmosphere introduction valve seat 22 is formed at the rear end of the valve piston 14, and is annular. The negative pressure introduction valve seat 21 is formed in the valve cylinder 12 so as to surround the atmosphere introduction valve seat 22. In addition, a valve holder 25 is fitted and fixed to the rear portion of the valve cylinder 12, and a valve body 23 formed of an elastic material such as rubber in common with the air introduction valve seat 22 and the negative pressure introduction valve seat 21 includes the valve It is held at the front end of the holder 25. Further, the valve spring 24 is contracted between the valve body 23 and the input rod 15 so as to exert a spring force for urging the valve body 23 so as to be seated on the negative pressure introduction valve seat 21 and the atmospheric introduction valve seat 22. Is done.
[0018]
Inside the valve cylinder 12, the valve piston 14 is surrounded on the front side of the valve body 23, and the front annular chamber 26 leading to the negative pressure chamber 10 and the back side of the valve body 23 are faced, and the working chamber 11 is communicated. A rear annular chamber 27 is formed.
[0019]
Both ends of a stretchable boot 28 that covers the valve cylinder 12 are attached to the rear end of the support cylinder portion of the rear shell half 7 and the input rod 15, and the inner end of the valve body 23 is attached to the rear end of the boot 28. An air inlet 29 leading to is provided. Further, a filter 30 for purifying the air flowing from the air introduction port 29 is interposed between the input rod 15 and the valve holder 25.
[0020]
A key member 31 that defines the backward limit of the booster piston 8 and the valve piston 14 is attached to the valve cylinder 12 so as to be movable within a certain distance in a direction along one diameter line of the valve cylinder 12. Thus, when the booster piston 8 is retracted, the end of the key member 31 protruding from the outer periphery of the valve cylinder 12 is brought into contact with the locking ring 13, so that the retracting limit of the booster piston 8 is restricted, and the key member 31 is reacted. The backward limit of the valve piston 14 is regulated by receiving the piston 19.
[0021]
An operating piston 32 protruding forward is integrally provided at the front end of the valve cylinder 12, and the reaction force piston 19 is fitted to the operating piston 32 so as to be relatively slidable. A cup body 33 is fitted on the outer periphery of the operating piston 32 so as to be relatively slidable. The cup body 33 is filled with an elastic piston 34 facing the operating piston 32 and the reaction force piston 19. A retainer 35 is in contact with the front surface of the cup body 33, and a return spring 36 is contracted between the front shell half 6 and the retainer 35.
[0022]
An output rod 37 is integrally projected on the front surface of the cup body 33, and the output rod 37 is connected to the piston 38 of the master cylinder M.
[0023]
In such a resting state of the negative pressure booster B, the booster piston 8 and the valve piston 14 are held at the retreat limit by the key member 31, and the valve element 23 is seated on the atmosphere introduction valve seat 22 but slightly from the atmosphere introduction valve seat 21. I'm sitting away. As a result, the communication between the air inlet 29 and the working chamber 11 is blocked, the negative pressure chamber 10 and the working chamber 11 are in communication, and both the chambers 10 and 11 have the same pressure. The cylinder 12 is held in the retracted position by the urging force of the return spring 36.
[0024]
When the brake pedal 20 is depressed to perform a braking operation, the valve body 23 is seated on the negative pressure introduction valve seat 21 and is separated from the atmosphere introduction valve seat 22, and the communication between the negative pressure chamber 10 and the working chamber 11 is established. Is cut off and the working chamber 11 leads to the atmospheric pressure introduction port 29, and the pressure of the working chamber 11 becomes higher than that of the negative pressure chamber 10. As a result, the booster piston 8 obtains a forward thrust according to the pressure difference between the two chambers 10 and 11, and moves forward with the valve cylinder 12, the operating piston 32, the elastic piston 34, the cup body 33, and the output rod 37. The piston 38 of the master cylinder M is pressed by the output rod 37. At this time, the elastic piston 34 is compressed by the reaction force and bulges toward the reaction force piston 19, but the reaction force is not transmitted to the input rod 15 until the bulging portion contacts the reaction force piston 19. The output of the output rod 37 exhibits a jumping characteristic that rises rapidly.
[0025]
After the elastic piston 34 comes into contact with the reaction force piston 19, a part of the reaction force of the output rod 37 is fed back to the input rod 15 through the elastic piston 34. The magnitude of the output of the rod 37 can be perceived. Thus, the output of the output rod 37 increases with a boost ratio determined by the ratio of the pressure receiving areas of the working piston 32 and the reaction force piston 19 in contact with the elastic piston 34.
[0026]
The output of the output rod 37 after reaching the boost limit point at which the pressure difference between the negative pressure chamber 10 and the working chamber 11 reaches the maximum is the maximum thrust of the booster piston 8 due to the pressure difference and the operation to the input rod 15. Sum with input.
[0027]
Referring to FIG. 2 and FIG. 3 together, the front shell half 6 has a cylindrical portion 40 whose rear end is coupled to the rear shell half 7 and basically has a smaller diameter toward the front. An end wall portion 41 formed and connected to the front end of the cylindrical portion 40; a flat mounting portion 42 provided at the front end of the end wall portion 41 so that the master cylinder M is fastened to a flange 45 provided at the rear portion; The small-diameter cylindrical portion 43 that is continuous with the central portion of the portion 42 and sinks into the booster shell 5 side, and an inward flange 44 provided at the inner end of the small-diameter cylindrical portion 43 are integrally provided.
[0028]
The rear end portion of the master cylinder M is fitted to the small-diameter cylindrical portion 43 with a seal member 46 interposed between the inward flange 44 and a mounting portion 42 and a flange 45 that abuts the mounting portion 42 from the front. Is concluded.
[0029]
The flange 45 and the mounting portion 42 are formed long in a direction along a virtual straight line L orthogonal to the axis of the master cylinder M, with a rhombus having four rounded corners as a basic shape. It fastens with a pair of arranged fastening locations P and P. That is, the heads 48a of bolts 48 inserted through the insertion holes 47 provided at the fastening points P, P are fixed to the inner surface of the mounting portion 42 and screwed to the bolts 48 penetrating the flange 45. By tightening the nuts 49 to be joined, the flange 45 and the attachment portion 42 are fastened.
[0030]
The end wall portion 41 has a tapered portion 41a that increases in diameter toward the rear, a pair of step portions 41b and 41b formed between the tapered portion 41a and the mounting portion 42, and between the tapered portion 41a and the cylindrical portion 40. It is comprised with a pair of flat part 41c, 41c arrange | positioned.
[0031]
The taper portion 41 a is formed so as to linearly connect the outer edge of the attachment portion 42 and the front end edge of the cylindrical portion 40 on a straight line passing through the axis of the front shell half 6 perpendicular to the virtual straight line L. However, since the attachment portion 42 is formed long in the direction along the imaginary straight line L, the taper portion 41a and the taper portion 41a are arranged at positions shifted from the straight line passing through the axis of the front shell half 6 perpendicular to the imaginary straight line L. A step is generated between the outer edges of the mounting portion 42, and both the step portions 41 b and 41 b are perpendicular to the virtual straight line L and deviated from a straight line passing through the axis of the front shell half 6 and the tapered portion 41 a and 41 b. It is formed so as to connect the outer edges of the attachment portion 42. Further, the large-diameter end of the taper portion 41a has a position that is inwardly spaced from the front end edge of the cylindrical portion 40 at a position that is perpendicular to the virtual straight line L and deviates from a straight line that passes through the axis of the front shell half 6. The two flat portions 41c and 41c are large portions of the front end edge of the cylindrical portion 40 and the tapered portion 41a at a position spaced inward from the front end edge of the cylindrical portion 49. It is formed so as to connect between the radial ends.
[0032]
Further, at the large diameter end portion of the taper portion 41a at positions of 45 degrees on both sides from the imaginary straight line L, concave portions 50, which are recessed in an arc shape on the radially inner side of the front shell half body 6, are formed. A negative pressure introducing pipe 51 is disposed in one of the recesses 50.
[0033]
In such an end wall portion 41, the cross-sectional shape of the end wall portion 41 along the plane passing through the axis of the front shell half 6 perpendicular to the virtual straight line L is the outer edge of the mounting portion 42 and the front end edge of the cylindrical portion 40. connects between would be formed in a straight line shape, and the cross-sectional shape of the end wall portion 41 along a plane passing through the imaginary straight line L and the axis of the front shell half 6, a plurality of angled mutually A straight line is formed so as to connect the outer edge of the mounting portion 42 and the front end edge of the cylindrical portion 40.
[0034]
Next, the operation of this embodiment will be described. The location where the load acting on the end wall portion 41 of the front shell half 6 is maximized by the hydraulic pressure generated by the master cylinder M, that is, the fastening location P of the flange 45 and the attachment portion 42. , P are arranged on a virtual straight line L, and an end wall portion 41 is formed so as to be connected to the outer edge of the mounting portion 42 and the front end edge of the cylindrical portion 40. . Therefore, on the virtual straight line L, it is possible to prevent stress concentration from occurring at the connecting portion between the end wall portion 41 and the cylindrical portion 40 by sufficiently bending the end wall portion 41 to relax the stress.
[0035]
On the other hand, the cross-sectional shape of the end wall portion 41 along a plane passing through the axis of the front shell half 6 is orthogonal to the virtual straight line L, connects between the front edge of the outer edge and the cylindrical portion 40 of the mounting portion 42 straight linear Therefore, sufficient rigidity can be obtained.
[0036]
As a result, it is possible to improve the strength of the end wall portion 41, that is, the front shell half body 6 as a whole, while reducing the weight of the end wall portion 41, that is, the front shell half body 6 without using an unnecessary reinforcing member. .
[0037]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. It is.
[0038]
【The invention's effect】
As described above, according to the present invention, on the virtual straight line where the load acting on the end wall portion due to the hydraulic pressure generated by the master cylinder becomes the largest, that is, on the virtual straight line where the fastening portion of the flange and the mounting portion is arranged, the angles are mutually different. Since the end wall portion is formed so as to connect between the outer edge of the attachment portion and the front end edge of the cylindrical portion, the end wall portion is sufficiently bent on the virtual straight line so that stress is applied. By relaxing, it is possible to prevent stress concentration from occurring in the connecting portion between the end wall portion and the cylindrical portion. On the other hand, sufficient rigidity can be obtained by forming the end wall portion so that the outer edge of the attachment portion and the front end edge of the cylindrical portion are connected in a straight line at the portion of the end wall portion orthogonal to the virtual straight line. As a result, it is possible to improve the strength of the entire end wall portion while reducing the weight of the end wall portion without using an unnecessary reinforcing member.
[Brief description of the drawings]
FIG. 1 is a longitudinal side view of a negative pressure booster.
FIG. 2 is a front view of the front shell half.
3 is a cross-sectional view taken along line 3-3 of FIG.
[Explanation of symbols]
5 ... Booster shell 6 ... Front shell half 7 ... Rear shell half 40 ... Cylinder part 41 ... End wall part 42 ... Mounting part 45 ... Flange B ...・ Negative pressure booster L ・ ・ ・ Virtual straight line M ・ ・ ・ Master cylinder P ・ ・ ・ Fastening point

Claims (2)

A front shell half (6) which forms a booster shell (5) in cooperation with the rear shell half (7), a cylindrical portion (40) whose rear end is coupled to the rear shell half (7); Basically, an end wall portion (41) formed to have a smaller diameter toward the front and continuing to the front end of the cylindrical portion (40), and an axis of a master cylinder (M) having a flange (45) at the rear portion A flat mounting portion (42) provided at the front end of the end wall portion (41) so as to be fastened to the flange (45) at a pair of fastening points (P) arranged on an orthogonal virtual straight line (L). ) In the shell structure of the negative pressure booster,
When a load is applied to the end wall (41) by the operation of the negative pressure booster (B) and the master cylinder (M), the end wall (41) is sufficiently bent on the virtual straight line (L). In order to relieve stress and to obtain sufficient rigidity at a portion orthogonal to the imaginary straight line (L) to increase the overall strength of the end wall portion (41),
The outer edge and the cylindrical portion of the cross-sectional shape of the end wall portion along a plane passing through the axis of the imaginary straight line (L) perpendicular to the front shell half (6) (41), said mounting portion (42) ( It is formed on the connecting by a straight linear between front edge 40) Rutotomoni, the cross section of the end wall portion along a plane passing through the axis of the imaginary straight line (L) and the front shell half (6) (41) The negative pressure booster is characterized in that the shape is formed by a plurality of straight lines that form an angle with each other, and is formed so as to connect between the outer edge of the mounting portion (42) and the front end edge of the cylindrical portion (40). Shell structure. The large-diameter end of the end wall (41) has a plurality of recesses (50) that are recessed in an arc on the radially inner side of the front shell half (6). And spaced apart from each other in the circumferential direction at a position avoiding the plane passing through the axis of the shell half (6) and the plane passing through the axis of the front shell half (6) perpendicular to the virtual straight line (L). 2. The shell structure of a negative pressure booster according to claim 1, characterized in that a negative pressure introduction pipe (51) is arranged in one of the recesses (50).

Images