Patent Publication Number: US-2022221017-A1

Title: Anti-vibration device

Description:
TECHNICAL FIELD 
     The present invention relates to anti-vibration devices, and more particular to an anti-vibration device suitable for a mount of a drive source of a vehicle. 
     BACKGROUND ART 
     Conventionally, an anti-vibration device to be employed in a mount of a drive source of a vehicle, such an engine, a motor and the like, is configured such that a cylindrical outer cylinder and a substantially cylindrical shaft member inserted to be into the outer cylinder are linked and supported by an elastic member made of rubber, an input to the drive source generated due to behavior of the vehicle is absorbed by the elastic member to thereby prevent a vibration from being transmitted to a vehicle side. 
     As such an anti-vibration device, Patent Document  1  discloses that a shaft member is formed in a deformed shape so that a cross-section along an axial direction is recessed inwardly in a radial direction and that, by employing this shaft member, a free length of the elastic member from the outer cylinder to the shaft member is secured. 
     However, the above-mentioned anti-vibration device has a drawback that, since the cross-section along the axial direction is in the deformed shape, a production process and a cost are increased. 
     CITATION DOCUMENT 
     Patent Document 
     Patent Document 1: Japanese Unexamined Patent Application Publication No. 2018-21580. 
     SUMMARY OF THE INVENTION 
     Technical Problem 
     The present invention was made in view of the above-mentioned problem, and provides an anti-vibration device capable of improving a production efficiency while securing a free length of an elastic member required for an anti-vibration device. 
     Solution to Problem 
     As a configuration for solving the above-mentioned problem, there is provided an anti-vibration device including: a shaft member; and an elastic member that extends from the shaft member toward an outer side in a radial direction, in which the shaft member has an inner cylinder and four stopper portions that protrudes from a circumferential surface of the inner cylinder toward the outer side in the radial direction and that are mutually provided at intervals in a circumferential direction, and in which the elastic member contacts the shaft member at a position between stopper portions that are adjacent to each other in the circumferential direction. 
     Further, there is provided an anti-vibration device including: an outer cylinder; a shaft member that is provided in the outer cylinder; and an elastic member that links the outer cylinder and the shaft member, in which the shaft member has an inner cylinder and four stopper portions that protrudes from a circumferential surface of the inner cylinder toward an outer side in a radial direction and that are mutually provided at intervals in a circumferential direction, and in which the elastic member links the outer cylinder and the shaft member at a position between stopper portions that are adjacent to each other in the circumferential direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic plan view of an anti-vibration device; 
         FIG. 2  is a cross-sectional view in an axial direction of the anti-vibration device; and 
         FIG. 3  is a cross-sectional view in a radial direction of the elastic member. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, the present invention will be described in detail through embodiments of the invention; however, the following embodiments are not intended to limit the inventions set forth in the claims, and all of combinations of the features described in the embodiments are not necessarily essential to the solving means of the invention. 
     As illustrated in each figure, an anti-vibration device  1  includes an outer cylinder  10 , a shaft member  20  disposed within the outer cylinder  10 , and an elastic member  40  that elastically links the outer cylinder  10  and the shaft member  20 . The anti-vibration device  1  in this example is a device that is installed in plural numbers between a side surface of a drive source and a side surface forming a housing, when the drive source such as a motor is installed in the housing provided in a vehicle. In the following description, a case is exemplified, in which an object to be mounted on the vehicle is a motor, but the object may be a drive source such as an engine. In the following description, explanations with respect to directions will be given on the basis of a state in which the anti-vibration device  1  has been installed in the vehicle. 
     The outer cylinder  10  is made of a metal having high rigidity, such as aluminum, and is formed in a circular shape. One end side in an axial direction of the outer cylinder  10  is firmly fixed to the housing provided in the vehicle, for example, via a not-shown bracket, and the other end side is positioned so as to face the drive source. 
     As illustrated in  FIG. 1 , the shaft member  20 , like the outer cylinder  10 , is made of a metal having high rigidity such as aluminum, for example, and has an inner cylinder portion  22  positioned around a central axis of the outer cylinder  10 , and four stopper portions  30   a ;  30   b ;  30   c ;  30   d  that extend so as to protrude from an outer circumferential surface  24  of the inner cylinder  22  toward an inner circumferential surface  12  of the outer cylinder  10 . As illustrated in  FIG. 2 , the shaft member  20  extends continuously along the axial direction of the outer cylinder  10 , that is, along a right and left direction orthogonal to a front and back direction and a vertical direction of the vehicle, and a dimension in the axial direction is set to be longer than a dimension in the axial direction of the outer cylinder  10 . Specifically, the dimension of the shaft member  20  is so set that end surfaces  26   a ;  26   b  in the axial direction of the shaft member  20  substantially equally project in the axial direction from end edges  10   a ;  10   b  in the axial direction of the outer cylinder  10 , respectively. 
     The inner cylinder portion  22  is formed to have a diameter smaller than an outer diameter of the outer cylinder  10 , and a bolt hole  22   a  is formed on an inner circumference side thereof. The bolt hole  22   a  is a through hole that penetrates the inner cylinder  22  in the axial direction. The bolt hole  22   a  is formed by a perfectly circular hole wall  23   a  and a hole wall  23   b  that is convex toward a stopper portion  30   a  direction. 
     In bolt hole  22   a , a not shown bolt, which has a cross-sectional shape substantially identical to a cross-sectional shape formed by the hole walls  23   a ;  23   b , is inserted and fastened, and is firmly fixed (mounted) in a state in which a side surface of a not-shown drive source is in contact with the end surface  26   a  in the axial direction of the shaft member  20 . Incidentally, before the drive source is mounted and fixed, a center point p of the bolt hole  22   a  has been set in advance at a position slightly displaced to a stopper portion  30   a  side (upper side) from a center point of the outer cylinder  10 . On the other hand, when the drive source is mounted and fixed to the shaft member  20 , the shaft member  20  is displaced by a load of the drive source toward a stopper portion  30   c  side (lower side), and the center point p and the center point of the outer cylinder  10  are substantially aligned on the same axis. 
     Next, an explanation will be given as to the stopper portions  30   a ;  30   b ;  30   c ;  30   d  (hereinafter sometimes referred to as  30   a  to  30   d , and the like,). As illustrated in  FIG. 1 , the stopper portions  30   a  to  30   d  extend so as to project from an outer circumferential surface  24  of the inner cylinder portion  22  toward the outer cylinder  10  side. Each of the stopper portions  30   a  to  30   d  is provided at equal intervals (90° intervals in the example shown in the figure) along the circumferential direction of the inner tube portion  22 , and is arranged in a substantially cruciform in a plan view. Among the stopper portions  30   a  to  30   d , extension directions of the stopper portions  30   a ;  30   c  are in line with a vertical direction of the vehicle, and extension directions of the stopper portions  30   b ;  30   d  are in line with a front and back direction (advance/retract direction) of the vehicle. 
     Each of the stopper portions  30   a ;  30   c  linearly extends in the vertical direction, and a tip end  32  on the outer cylinder  10  side has a shape which is widened in the front and back direction than the other parts thereof. Each of the stopper portions  30   b ;  30   d  linearly extends in the front and back direction, and a lower part of the tip end  34  on the outer cylinder  10  side has a shape which is widened downward. Incidentally, a significance of the widened shape of the tip ends  32 ;  34  will be explained in conjunction with the shape of the elastic member  40  described below. 
     The outer cylinder  10  having the above-described configuration and the shaft member  20  arranged within the inner circumference of the outer cylinder  10  are integrated by the elastic member  40  filled in the outer cylinder  10 . Hereafter, an explanation will be given as to the shape of the elastic member  40  with reference to  FIG. 3  in particular. The elastic member  40  is a rubber that is filled using, as a mold frame, a not-shown shaft body that forms gap portions  60   a ;  60   b ;  60   c ;  60   d  so as to be in correspondence with the outer cylinder  10 , the shaft member  20 , and the stopper portions  30   a ;  30   b ;  30   c ;  30   d . As the rubber having been filled is vulcanized, the outer cylinder  10  and the shaft member  20  are elastically integrated. 
     The elastic member  40  generally includes a plurality of linking portions  46   a  to  46   d  that extend in a radial direction over the inner circumferential surface  12  of the outer cylinder  10  and the outer circumferential surface  24  of the inner cylinder portion  22  of the shaft member  20 , buffer portions  50   a  to  50   d  that are formed to cover the outer circumferential surfaces of the plurality of stopper portions  30   a  to  30   d  of the shaft member  20 , outer buffer portions  56   a ;  56   b  that are formed on the inner circumferential surface  12  of the outer cylinder  10 , and the gap portions  60   a  to  60   d  that are formed so as to correspond to each of the stopper portions  30   a  to  30   d  and which penetrate along the axial direction. 
     As shown by virtual lines, the linking portion  46   a  is a portion whose end on an outer side in the radial direction is in contact with the inner circumferential surface  12  of the outer cylinder  10  and whose end on an inner side in the radial direction is in contact, within a range between the stopper portion  30   a  and the stopper portion  30   b , with the outer circumferential surface  24  of the inner cylinder  22  and an outer peripheral surface of a straight line part of the stopper portion  30   a , and which extends upwardly and forwardly from the shaft member  20  toward the outer cylinder  10 . The linking portion  46   b  is a portion whose end on the outer side in the radial direction is in contact with the inner circumferential surface  12  of the outer cylinder  10  and whose end on the inner side in the radial direction is in contact, within a range between the stopper portion  30   b  and the stopper portion  30   c , with the outer circumferential surface  24  of the inner cylinder  22  and an outer peripheral surface of a straight line part of the stopper portion  30   c , and extends downwardly and forwardly from the shaft member  20  toward the outer cylinder  10 . The linking portion  46   c  is a portion whose end on the outer side in the radial direction is in contact with the inner circumferential surface  12  of the outer cylinder  10  and whose end on the inner side in the radial direction being in contact, within a range between the stopper portion  30   c  and the stopper portion  30   d , with the outer circumferential surface  24  of the inner cylinder  22  and an outer peripheral surface of a straight line part of the stopper portion  30   c , and extends downwardly and backwardly from the shaft member  20  toward the outer cylinder  10 . The linking portion  46   d  is a portion, an end of which on the outer side in the radial direction whose end on the outer side in the radial direction is in contact with the inner circumferential surface  12  of the outer cylinder  10  and whose end on the inner side in the radial direction being in contact, within a range between the stopper portion  30   d  and the stopper portion  30   a , with the outer circumferential surface  24  of the inner cylinder portion  22  and an outer peripheral surface of a straight line part of the stopper portion  30   a , and extends upwardly and backwardly from the shaft member  20  toward the outer cylinder  10 . 
     Among the above-mentioned linking portions  46   a  to  46   d , free lengths of the upwardly positioned linking portions  46   a ;  46   d  are set slightly longer than free lengths of the downwardly positioned linking portions  46   b ;  46   c  in a no-load state, which is a state in which the load of the motor is not applied. On the other hand, when the load of the motor is applied, the upwardly positioned linking portions  46   a ;  46   d  are pulled downward and the downwardly positioned linking portions  46   b ;  46   c  are compressed downward, thus the free lengths of all the linking portions  46   a  to  46   d  are substantially equalized, and each of the linking portions  46   a  to  46   d  becomes able to exhibit the elastic force in a well-balanced manner against inputs applied to the shaft member  20  from the vertical direction, the front and back direction, or a composite input of the inputs from these directions. 
     As described above, because the linking portions  46   a  to  46   d  of the elastic member  40  according to the present embodiment are configured to extend between the outer cylinder  10  and the shaft member  20  within the region formed between the cruciform stopper portions  30   a  to  30   d  arranged along the circumferential direction, the free length, which is the dimension in the radial direction from the outer cylinder  10  to the shaft member  20 , can be secured sufficiently, and spring characteristics (for example, spring ratio, durability, load durability, and so on.) of the elastic member  40  can be finely tuned in accordance with characteristics of vibration of the motor, which is generated by behaviors of the vehicle during driving, braking, steering and the like. 
     Next, an explanation will be given as to the buffer portions  50   a  to  50   d . The buffer portions  50   a  to  50   d  are portions that correspond to the widened tip ends  32 ;  34  of the stopper portions  30   a ;  30   b ;  30   c ;  30   d , and that are formed to cover the periphery of the widened tip ends  32 ;  34 . The buffer portions  50   a ;  50   c , which correspond to the upper and lower tip ends  32 ;  32 , are substantially arcuate thick portions that are respectively opposed to each other, sandwiching gap portions  60   a ;  60   c  described later, in the vertical direction to the outer buffer portions  56   a ;  56   b  formed on the inner circumferential surface  12  of the outer cylinder  10 . The buffer portions  50   a ;  50   c  mitigate and absorb the impact when the stopper portions  30   a ;  30   c  approach and abut against the outer cylinder  10  side due to the displacement (input) of the shaft member  20  toward the vertical direction caused mainly by the behavior of the vehicle toward the vertical direction. In addition, as the tip ends  32 ;  32  have been widened, areas of the thick portions are increased and thus the buffer range (abutment range) is extended. 
     The buffer portions  50   b ;  50   d  that correspond to the front and back tip ends  34 ;  34  are substantially rectangular-shaped thick portions that are respectively opposed to each other, sandwiching gap portions  60   b ;  60   d  described later, in the front and back direction to the inner circumferential surface  12  of the outer cylinder  10 . The buffer portions  50   b ;  50   d  mitigate and absorb the impact when the stopper portions  30   b ;  30   d  approach and abut against the outer cylinder  10  side due to the displacement (input) of the shaft member  20  in the front and back direction caused mainly by the behavior of the vehicle in the front and back direction. In addition, since lower portions of the tip ends  34 ;  34  are widened downward in an arc shape, areas of the thick portions, especially of the downward thick portion is increased, hence the buffer range against the downward input, which becomes dominant when the vehicle is running, is expanded. Upper parts of the tip ends  34 ;  34  may also be widened, however, when taking the rubber flow into consideration, it is preferable to have the shape that is widened downward only. 
     The outer buffer portions  56   a ;  56   b  are thick portions that respectively protrude, sandwiching the gap portions  60   a ;  60   c , toward the buffer portions  50   a ;  50   c  side on the inner side in the radial direction. As described above, since the gap portions  60   a ;  60   c  and the buffer portions  50   a ;  50   c , which are formed respectively on the stopper portions  30   a ;  30   c , are opposed to each other in the vertical direction and are made thick, when the stopper portions  30   a ;  30   c  approach the outer cylinder  10  side, the thick buffer portions  50   a ;  50   c  and the outer buffer portions  56   a ;  56   b  abut against each other while mitigating and absorbing the impact, hence the anti-vibration performance against the input in the vertical direction is enhanced. Further, in comparison with the inner circumferential surface  12  of the outer cylinder  10  that opposes the stopper portions  30   b ;  30   d  in the front and back direction, thick portions corresponding to the outer buffer portions  56   a ;  56   b  have not been formed on the inner circumferential surface  12 . 
     This is because the following was taken into consideration. Namely, because the displacement direction of the stopper portions  30   a ;  30   c  against the input in the vertical direction is substantially limited to the vertical direction, and the buffer portions  50   a ;  50   c  respectively abut against the outer buffer portions  56   a ;  56   b  in a substantially right-opposite manner, whereas at the time when an input in the front and back direction is applied, an input component in the vertical direction coexists, thus the displacement directions of the stopper portions  30   b ;  30   d  are not stable and blurring occurs. On the other hand, the thickness of the buffer portions  50   b ;  50   d  that correspond to the stopper portions  30   b ;  30   d  is made slightly thicker than that of the buffer portions  50   a ;  50   c , so that the displacement is sufficiently mitigated and absorbed even in a case where the stopper portions  30   b ;  30   d  are displaced in the front and back direction with blurring in the vertical direction and abut against the inner circumferential surface  12  of the outer cylinder  10 . 
     Next, an explanation will be given as to the gap portions  60   a ;  60   c , which are formed in the elastic member  40  and arranged by being separated upwardly and downwardly. The gap portion  60   a  is a space provided between the buffer portion  50   a  formed on the stopper portion  30   a  and the outer buffer portion  56   a  formed on the outer cylinder  10  side. The gap portion  60   a  has a buffer section kl which is formed by peripheral walls extending linearly in the right and left direction and vertically facing with each other and which allows the abutment between the buffer portion  50   a  and the outer buffer portion  56   a  in response to an upward input, and a regulation section k 2  which is formed symmetrically in the front and back direction of the buffer section kl and is formed by peripheral walls extending in a substantially spade-shaped manner. The shape of the regulating section k 2  can be changed as necessary in consideration of the load of the motor to be mounted, the characteristics of the vehicle, or the rubber flow at the time when the rubber is filled. 
     The gap portion  60   c  is a space provided between the buffer portion  50   c  formed on the stopper portion  30   c  and the outer buffer portion  56   b  formed on the outer cylinder  10  side. The gap portion  60   c , like the gap portion  60   a , has a buffer section k 3  which is formed by peripheral walls extending linearly in the right and left direction and which allows the abutment between the buffer portion  50   c  and the outer buffer portion  56   b  in response to a downward input, and a regulation section k 4  which is formed symmetrically in the front and back direction of the buffer section k 3  and is formed by peripheral walls extending in a substantially spade-shaped manner. The overall shape of the buffer section k 3  and the regulation section k 4  is enlarged in comparison with the buffer section kl and the regulation section k 2  of the gap portion  60   a  located above to thereby increase a clearance. This is set so as to cope with the downward input that becomes dominant when the vehicle is running. 
     Next, an explanation will be given as to the gap portions  60   b ;  60   d . Incidentally, since the gap portions  60   b ;  60   d  are formed symmetrically, the explanation will be given using one gap portion  60   b  as an example. The gap portion  60   b  is a space provided between the buffer portion  50   b  formed on the stopper portion  30   b  and the rubber formed on the inner circumferential surface  12  of the outer cylinder  10 . The gap portion  60   b  has a buffer section k 5  which is formed by a peripheral wall extending in an arc shape in the vertical direction along the inner circumferential surface  12  of the outer cylinder  10  and which allows the abutment between the buffer portion  50   b  and the rubber formed on the inner circumferential surface  12  of the outer cylinder  10  in response to a forward input, and restriction sections k 6 ; k 7  which are formed upward and downward of the buffer section k 5  and formed by a peripheral wall that tapers and extends toward a direction of the center point p of the inner cylinder  22 . In comparison with the regulation section k 6  and the regulation section k 7  in terms of the shape thereof, the arc on the center point p side forming the regulation section k 6  is set to be a gentler arc shape than the arc on the center point p side forming the regulation section k 7 . This prevents stress concentration from occurring, especially in response to the downward input. 
     As explained above, with the anti-vibration device  1  according to the present embodiment, since the shaft member  20  has four stopper portions  30   a  to  30   d  that protrude from the outer circumferential surface  24  of the inner cylinder portion  22  toward the outer cylinder  10  and that are mutually provided at intervals in the circumferential direction, or in other words, radially extended with the center of the inner cylinder portion  22  as a base point, and the plurality of linking portions  46   a  to  46   d  of the elastic member  40  link the outer cylinder  10  and the shaft member  20  at the position between each of the stopper portions  30   a  to  30   d  which are adjacent to each other in the circumferential direction, respectively, the free lengths of the linking portions  46   a  to  46   d  are secured, hence the degree of freedom in tuning the spring characteristics of the elastic member  40  can be improved. In addition, since the cross-section in the axial direction is constant, the shaft member  20  can be manufactured continuously by extrusion molding or the like, thus the production efficiency can be improved. 
     Further, since the outer buffer portions  56   a ;  56   b  that are formed by the elastic member  40  and that protrude toward the tip ends  32 ;  32 , respectively, are provided on the inner circumferential surface  12  of the outer cylinder  10  opposing the tip ends  32 ;  32  of the stopper portions  30   a ;  30   c  extending in the vertical direction, a sufficient buffering effect can be obtained against the input in the vertical direction, hence the anti-vibration effect can be improved. Incidentally, portions corresponding to the outer buffer portions  56   a ;  56   b  may be formed on the inner circumferential surface  12  of the outer cylinder  10  opposing the tip ends  34 ;  34  of the stopper portions  30   b ;  30   d  extending in the front and back direction, however, in consideration of the above-mentioned reason, it may be configured not to be provided with such portions. 
     Further, as the downwardly projecting widened parts are formed on the tip ends  34 ;  34  of the stopper portions  30   b ;  30   d  that extend in the front and back direction, the buffering range for particularly dominant downward inputs can be enlarged. 
     In summary, the present invention can be described as follows. That is, an anti-vibration device according to an aspect of the invention includes: a shaft member; and an elastic member that extends from the shaft member toward an outer side in a radial direction, in which the shaft member has an inner cylinder and four stopper portions that protrudes from a circumferential surface of the inner cylinder toward the outer side in the radial direction and that are mutually provided at intervals in a circumferential direction, and in which the elastic member contacts the shaft member at a position between stopper portions that are adjacent to each other in the circumferential direction. 
     According to this configuration, since the elastic member contacts the shaft member at the position between stopper portions that are adjacent to each other in the circumferential direction, the free length of the elastic member to the shaft member can be secured without the need to make the cross-sectional shape of the shaft member to be deformed, and the shaft member can be obtained continuously by extrusion molding or the like, thus the production efficiency can be improved. 
     An anti-vibration device according to another aspect of the invention includes: an outer cylinder; a shaft member that is provided in the outer cylinder; and an elastic member that links the outer cylinder and the shaft member, in which the shaft member has an inner cylinder and four stopper portions that protrudes from a circumferential surface of the inner cylinder toward an outer side in a radial direction and that are mutually provided at intervals in a circumferential direction, and in which the elastic member links the outer cylinder and the shaft member at a position between stopper portions that are adjacent to each other in the circumferential direction. 
     Further, the anti-vibration device may be configured such that the four stopper portions respectively protrude in a vertical direction corresponding to a vibration direction of an object and in a front and back direction, and, on an inner circumferential surface of the outer cylinder facing a tip end of a stopper portion that extends in the vertical direction, a buffer portion is provided, which is formed by the elastic member and which protrudes toward a tip end side. 
     Further, the anti-vibration device may be configured such that the four stopper portions respectively protrude in a vertical direction corresponding to a vibration direction of an object and in a front and back direction, and on an inner circumferential surface of the outer cylinder facing a tip end of a stopper portion that extends in the vertical direction, a buffer portion is provided, which is formed by the elastic member and protrudes toward a tip end side. 
     Further, the anti-vibration device may be configured such that, on a tip end of a stopper portion that extends in the front and back direction among the four stopper portions, a widened part that protrudes downward is formed. 
     REFERENCE SIGN LIST 
       1 : Anti-vibration device,  10 : Outer cylinder ,  12 : Inner circumferential surface,  20 : Shaft member,  22 : Inner cylinder portion, 
       30   a  to  30   d : Stopper portion,  32 ;  34 : Tip end,  40 : Elastic member, 
       46   a - 46   d : Linking portion, 
       50   a - 50   d : (inner side) Buffer portion,  56   a ;  56   b : Outer buffer portion.