Abstract:
A brake boosting device wherein a vibration control member is provided to an end part of a return coil spring that is arranged inside a vehicle chamber and that is interposed between a booster body and an input rod. The vibration control member has provided thereto: a seat part that suppresses the vibration of the return coil spring and that is between the end part of the return coil spring and a support part that supports the end part; and a guide part that is provided integrally with the seat part and that fits with the inner periphery of the end part of the return coil spring at a prescribed radial tightening allowance.

Description:
TECHNICAL FIELD 
       [0001]    The preset invention relates to a brake boosting device, more particularly to a brake boosting device having a return coil spring between a booster body and an input rod. 
       BACKGROUND ART 
       [0002]    The brake boosting device of this type may be configured to have a return coil spring in a vehicle interior as described in, for example, PTL 1 below. 
       CITATION LIST 
     Patent Literature 
       [0003]    PTL 1: JP-A-2013-227016 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0004]    In the brake boosting device described in PTL 1, one end (front end) of a return coil spring is directly engaged with a booster body and the other end (rear end) of the return coil spring is directly engaged with a retainer (assembled to an input rod). Accordingly, when the return coil spring vibrates associated with the operation of the brake boosting device and resonates with the retainer, the booster body, or the like, then abnormal noise caused by this may be propagated to the passenger. Vibrations of the return coil spring are generated by an impact that occurs when the brake pedal stops in the initial position while the pedal is returned. 
         [0005]    The invention addresses (prevents the generation of abnormal noise caused by vibrations of the return coil spring) the above problem and is characterized by a brake boosting device, in which a vibration control member is provided in an end part of a return coil spring interposed between a booster body and an input rod, the return coil spring being disposed in a vehicle interior, and the vibration control member is provided with a seat part interposed between the end part of the return coil spring and a support part supporting the end part, the seat part suppressing vibrations of the return coil spring, and a guide part disposed integrally with the seat part, the guide part being fitted to an inner periphery or an outer periphery of the end part of the return coil spring via a predetermined radial tightening allowance. 
         [0006]    In embodying the above invention, the guide part may include a cylindrical base part and a plurality of arc-shaped projections provided at regular intervals in a circumferential direction on an outer periphery or an inner periphery of the base part, the plurality of arc-shaped projections being fitted to the inner periphery or the outer periphery of the end part of the return coil spring via a predetermined radial tightening allowance. In such a case, a connection portion between the seat part and the guide part may be provided with an annular recess part capable of housing the end part of the return coil spring. In addition, the vibration control member may be disposed integrally with an end part of a boot disposed between the booster body and the input rod, the end part being close to the booster body. In this case, a support part supporting the end part of the boot close to the booster body may be cylindrical, in the guide part supported by the support part, three or more outer peripheral projections may be provided at regular intervals in the circumferential direction on the outer periphery of the cylindrical base part, three or more inner peripheral projections maybe provided at regular intervals in the circumferential direction on the inner periphery of the cylindrical base part, and the outer peripheral projections and the inner peripheral projections maybe alternately disposed with a phase difference in the circumferential direction. 
         [0007]    In the brake boosting device according to the above invention, the end part of the return coil spring disposed in the vehicle interior is provided with the vibration control member and the vibration control member is provided with the seat part interposed between the end part of the return coil spring and the support part supporting the end part, the seat part suppressing vibrations of the return coil spring, and the guide part disposed integrally with the seat part, the guide part being fitted to the inner periphery or the outer periphery of the end part of the return coil spring via the predetermined radial tightening allowance. Therefore, vibrations of the return coil spring itself can be suppressed by the guide part. In addition, the transfer of vibrations from the return coil spring to the support part can be reduced by the seat part. Accordingly, occurrence of abnormal noise caused by vibrations of the return coil spring can be prevented. 
         [0008]    In embodying the above invention, when the connection portion between the seat part and the guide part is provided with the annular recess part capable of housing the end part of the return coil spring, the amount of engagement between the return coil spring and the guide part can be increased as compared with the case in which the recess part is not provided, thereby increasing the vibration suppression effects by the guide part. 
         [0009]    In addition, in embodying the above invention, when the vibration control member is disposed integrally with the end part of the boot installed between the booster body and the input rod, the end part being close to the booster body, the number of components can be reduced and simplicity and cost reduction can be achieved as compared with the case in which the vibration control member is configured separately from the boot. In addition, in this case, if the seat part interposed between the end part of the return coil spring and the support part supporting the end part is disposed in the end part of the boot, the sealing performance of the end surface of the boot can be improved. 
         [0010]    In addition, in embodying the above invention, when the support part supporting the end part of the boot close to the booster body is cylindrical, the guide part supported by the support part is provided with three or more outer peripheral projections at regular intervals in the circumferential direction on the outer periphery of the cylindrical base part and three or more inner peripheral projections at regular intervals in the circumferential direction on the inner periphery of the cylindrical base part, and the outer peripheral projections and the inner peripheral projections are alternately disposed with a phase difference in the circumferential direction, then the inner peripheral projections can be used to perform the centering of the boot with respect to the support part and the assemblability of the boot to the support part can be improved. In addition, in this case, the inner peripheral projections allow the outer peripheral projection to move radially inward. Therefore, when the return coil spring is tilted as the input rod is tilted, it is possible to suppress an increase (an increase of the surface pressure in the engagement part) in the engagement force of the return coil spring with respect to the guide part. Accordingly, the durability of the guide part can be improved by reducing the wear damage of the guide part caused by the return coil spring. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0011]      FIG. 1  is a vertical partial cross sectional side view illustrating a brake boosting device in a non-operation state according to a first embodiment of the invention. 
           [0012]      FIG. 2  is an enlarged cross sectional view illustrating the main part of  FIG. 1 . 
           [0013]      FIG. 3  is a side view illustrating only the boot in  FIG. 1 . 
           [0014]      FIG. 4  is a vertical cross sectional side view illustrating only the boot in  FIG. 3 . 
           [0015]      FIG. 5  is a cross sectional view taken along line  5 - 5  in  FIG. 3 . 
           [0016]      FIG. 6  is a vertical partial cross sectional side view illustrating the first embodiment in  FIG. 1  in an operation state. 
           [0017]      FIG. 7  is an enlarged cross sectional view illustrating the main part of a brake boosting device according to a second embodiment of the invention. 
           [0018]      FIG. 8  is a vertical partial cross sectional side view illustrating a brake boosting device according to a third embodiment of the invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0019]    Embodiments of the invention will be described below with reference to the drawings.  FIGS. 1 to 6  illustrate a vehicle brake boosting device according to a first embodiment of the invention. This brake boosting device  100  according to the first embodiment has a return coil spring  30  between a booster body  10  and an input rod  20 . In addition, a boot  40  is installed between the booster body  10  and the input rod  20 . 
         [0020]    The booster body  10  is configured so as to be assembled to a dash panel (not illustrated) and a rear end part  10 a is disposed in a vehicle interior. The input rod  20  is provided in the booster body  10  so as to be movable forward and backward, coupled to a rear end part lla of a plunger  11  at a spherical end part  21 , and coupled to a middle part  51  of a brake pedal lever  50  at a rear end part  22  so as to be tiltable. The plunger  11  assembled to the booster body  10  so as to be movable forward and backward. In addition, the brake pedal lever  50  is assembled to a pedal bracket  59  so as to be tiltable in a front-rear direction at an upper end part  52 , and a brake pedal  54  is assembled integrally with a lower end part  53 . 
         [0021]    The return coil spring  30  is disposed in the vehicle interior, engaged with the booster body  10  via a seat part  41  of the boot  40  at a front end part  31 , and engaged with a retainer  28  via an annular vibration control material  29  at a rear end part  32 . The retainer  28  is formed in a disc shape and assembled integrally with the middle part of the input rod  20  at the inner periphery part. The vibration control material  29  includes an annular seat part  29   a , interposed between the rear end part  32  of the return coil spring  30  and the retainer  28 , that suppresses vibrations of the return coil spring  30  and a cylindrical guide part  29   b , disposed integrally with the seat part  29   a , that is engaged with the inner periphery of the rear end part of the return coil spring  30  via a predetermined radial tightening allowance. The inner periphery of the guide part  29   b  is provided with inner peripheral projections (configured as in inner peripheral projections  42   b  described later) to be elastically engaged with the outer periphery of the retainer  28  and the outer periphery of the guide part  29   b  is provided with outer peripheral projections (configured as in outer peripheral projections  42   c  described later) to be fitted to the inner periphery of the rear end part of the return coil spring  30  via a predetermined radial tightening allowance. 
         [0022]    The boot  40  covers and protects the outer periphery of the plunger  11  and formed in a cylindrical shape using an elastic member such as rubber, the seat part  41  and a guide part  42  are integrally formed in the front end part to be assembled to a cylindrical support part  10   a   1  formed in the rear end part  10 a of the booster body  10 , and an annular mounting part  43  is formed integrally with the rear end part to be assembled to a neck part  23  of the input rod  20 . The seat part  41  and the guide part  42  constitute a vibration control member A provided in the front end part  31  of the return coil spring  30 , the seat part  41  extends radially outward at the front end of the guide part  42  and is formed in a circular shape, and the guide part  42  is formed in a cylindrical shape. 
         [0023]    In addition, the seat part  41  is interposed in the front-rear direction between the front end part  31  of the return coil spring  30  and the cylindrical support part  10   a   1  supporting the front end part  31  and functions to suppress vibrations of the return coil spring  30 . In contrast, the guide part  42  is fitted to the inner periphery of the front end part  31  of the return coil spring  30  via a predetermined radial tightening allowance and has the function of suppressing lateral vibrations (vibrations in the up-down direction in the drawing) of the return coil spring  30 . 
         [0024]    By the way, in the embodiment, the guide part  42  includes a cylindrical base part  42   a , the four inner peripheral projections  42   b  provided in the circumferential direction at regular intervals (at intervals of 90 degrees) on the inner periphery of the cylindrical base part  42   a , the four outer peripheral projections  42   c  provided in the circumferential direction at regular intervals (at intervals of 90 degrees) on the outer periphery of the cylindrical base part  42   a . The outer peripheral projections  42   c  and the inner peripheral projections  42   b  are alternately disposed with a phase difference (a phase difference of 45 degrees) in the circumferential direction (see  FIG. 5 ). The inner peripheral projections  42   b  have a predetermined length in the axial direction, have a semispherical cross section, and are elastically engaged with the outer periphery of the cylindrical support part  10   a   1  of the booster body  10  at an end (inner end). The outer peripheral projections  42   c  have a necessary length in the axial direction (longer than the length in the axial direction of the inner peripheral projections  42   b ), have an arc-shaped cross section, and elastically engaged with the inner periphery of the front end part  31  of the return coil spring  30  at an end (outer end). 
         [0025]    In the brake boosting device  100  according to the first embodiment configured as described above, the vibration control member A is provided so as to correspond to the front end part  31  of the return coil spring  30  disposed in the vehicle interior and the vibration control member A is provided with the seat part  41 , interposed between the front end part  31  of the return coil spring  30  and a cylindrical support part llal supporting the front end part  31 , that suppresses vibrations of the return coil spring  30  and the guide part  42 , disposed integrally with the seat part  41 , that is fitted to the inner periphery of the front end part of the return coil spring  30  via a predetermined radial tightening allowance. Therefore, the vibrations of the front end part  31  itself in the return coil spring  30  can be suppressed by the guide part  42 . In addition, transfer of vibrations from the front end part  31  of the return coil spring  30  to the rear end part  10   a  of the booster body  10  can be reduced by the seat part  41 . In addition, since the vibration control material  29  is provided so as to correspond to the rear end part  32  of the return coil spring  30 , the same effects as in the above vibration control member A can also be obtained by the vibration control material  29 . Accordingly, occurrence of abnormal noise caused by vibrations of the return coil spring  30  can be prevented. 
         [0026]    In addition, in the brake boosting device  100  according to the first embodiment, the vibration control member A is disposed integrally with the end part of the boot  40  installed between the booster body  10  and the input rod  20 , the end part being close to the booster body. Therefore, the number of components can be reduced and simplicity and cost reduction can be achieved as compared with the case in which the vibration control member A is configured separately from the boot  40 . In addition, in the first embodiment, since the seat part  41  of the vibration control member A is provided in the front end part of the boot  40 , the sealing performance of the front end surface of the boot can be improved. 
         [0027]    In addition, in the brake boosting device  100  according to the above first embodiment, the support part  10   a   1  supporting the end part (front end part) of the boot  40  close to the booster body is formed in a cylindrical shape, the guide part  42  supported by the support part  10   a   1  is provided with the four outer peripheral projections  42   c  provided at regular intervals in the circumferential direction on the outer periphery of the cylindrical base part  42   a  and the four inner peripheral projections  42   b  provided at regular intervals in the circumferential direction on the inner periphery of the cylindrical base part  42   a , and the outer peripheral projections  42   c  and the inner peripheral projections  42   b  are alternately disposed with a phase difference in the circumferential direction. 
         [0028]    Therefore, the centering of the boot  40  with respect to the support part  10   a   1  (the booster body  10 ) can be performed using the inner peripheral projections  42   b  and the assemblability of the boot  40  to the support part  10   a   1  can be improved. In addition, in the embodiment, the inner peripheral projections  42   b  allow the outer peripheral projections  42   c  to move radially inward. Therefore, when the return coil spring  30  is tilted as the input rod  20  is tilted (the case illustrated in  FIG. 6 ), it is possible to suppress an increase (an increase in the surface pressure in the engagement part) in the engagement force of the return coil spring  30  with respect to the guide part  42 . Accordingly, the durability of the guide part  42  can be improved by reducing the wear damage of the guide part  42  caused by the return coil spring  30 . 
         [0029]    Although the four inner peripheral projections  42   b  and the four outer peripheral projections  42   c  of the guide part  42  are provided in the first embodiment above, the number of the inner peripheral projections  42   b  and the number of the four outer peripheral projections  42   c  may be changed as appropriate as long as they are three or more. In addition, in the first embodiment described above, since the input rod  20  is tilted as illustrated in  FIG. 6  when the brake pedal  54  is depressed, an annular recess part (recessed groove)  44  for housing the end of the return coil spring  30  may be provided in the connection portion between the seat part  41  and the guide part  42  as in a second embodiment illustrated in  FIG. 7 . In this case, as compared with the first embodiment described above, the amount of engagement (in the radial direction) between the front end part  31  of the return coil spring  30  and the guide part  42  can be increased, vibration suppression effects by the guide part  42  can be increased, it is possible to suppress an increase (an increase of the surface pressure in the engagement part) in the engagement force of the return coil spring  30  with respect to the guide part  42  when the return coil spring  30  is tilted as the input rod  20  is tilted (the case illustrated in  FIG. 6 ), and the durability of the guide part  42  can be improved. 
         [0030]    In addition, in the first embodiment described above, although the invention is embodied to have a structure in which the seat part  41  and the guide part  42  are included in the vibration control member A provided so as to correspond to the front end part  31  of the return coil spring  30  disposed in the vehicle interior, the invention may be embodied to have a structure in which a seat part  141  and a guide part  142  are included in the vibration control member A as in a third embodiment illustrated in  FIG. 8 . The seat part  141  extends radially inward at the front end of the guide part  142  and is interposed in the front-rear direction between the front end part  31  of the return coil spring  30  and the cylindrical support part  10   a   1  supporting the front end part  31 . In contrast, the guide part  142  is fitted to the outer periphery of the front end part  31  of the return coil spring  30  via a predetermined radial tightening allowance and the inner periphery is provided with the inner peripheral projections (having a similar function as in the outer peripheral projections  42   c ) elastically engaged with the outer periphery of the front end part  31  of the return coil spring  30  at the end (inner end), and the outer periphery is provided with the outer peripheral projections (having a similar function as the inner peripheral projections  42 b) elastically engaged with the inner periphery of the cylindrical support part  10   a   1  of the booster body  10  at the end (outer end). 
         [0031]    Although the vibration control member A is disposed integrally with the end part of the boot  40  (close to the booster body) installed between the booster body  10  and the input rod  20  in the above embodiments, the invention may be embodied so that the vibration control member A is provided separately from the boot  40  as in, for example, the vibration control material  29  illustrated in  FIG. 1 .