Abstract:
In a vibration damping apparatus for supporting an engine on a vehicular body, an elastic member damps a vibration developed from the engine, a stopper is brought in contact with the elastic member to limit a transmission of a fluctuation developed on the engine therethrough, and a vehicular body support member integrated with the elastic member to fix the elastic member on the vehicular body, the elastic member including a stopper fixing portion placed at a first position opposite to a second position faced toward the engine to fix the stopper at the first position and the stopper including a bending portion, one side thereof with respect to the bending portion being fixed onto the engine and the other side thereof with respect thereto being fixed onto the stopper fixing portion of the elastic member so as to grasp the elastic member between both sides of the stopper.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to a vibration damping apparatus for supporting an engine to a vehicular body such as an engine mount and, more particularly, relates to a stopper structure of the vibration damping apparatus. 
   2. Description of the Related Art 
   A stopper of a previously proposed vibration damping apparatus serves to limit a fluctuation of an engine when an elastic body whose inner side is reinforced by an iron plate or so forth is brought in contact with (or struck on) the stopper against a large fluctuation in a rolling of the engine during a start of the engine. However, this stopper has adopted a structure of receiving a load imposed due to a contact of the stopper with the elastic body in a cantilever arm (a beam supported only one end or one tip of a bending portion not fixed). Hence, if an engine drive torque is raised due to an increase in output of the engine, the stopper tends to yield according to a heavy load imposed due to a strike of the stopper against the elastic body. Hence, a limitation of the fluctuation of the engine becomes insufficient due to the yield of the stopper. In order to provide a sufficient limitation of the fluctuation of the engine, an increase in a thickness of the stopper can be considered. 
   SUMMARY OF THE INVENTION 
   However, since the increase in the thickness of the stopper causes a further problem of an increase of a weight of the stopper and a difficulty in making a bend forming. Furthermore, large mounts of labor hour and labor cost are required to determine an optimum form of the stopper which can suppress the above-described further problem. 
   It is, hence, an object of the present invention to provide a vibration damping apparatus for supporting an engine on a vehicular body which can sufficiently limit a large fluctuation in a rolling direction of the engine during a start of the vehicle without increasing the thickness of the stopper. 
   The above-described object can be achieved by providing a vibration damping apparatus for supporting an engine on a vehicular body, comprising: an elastic member to damp a vibration developed from the engine; a stopper brought in contact with the elastic member to limit a transmission of a fluctuation developed on the engine therethrough; and a vehicular body support member integrated with the elastic member to fix the elastic member on the vehicular body, the elastic member including a stopper fixing portion placed at one position opposite to the other position thereof faced toward the engine to fix the stopper at the first position and the stopper including a bending portion, one side thereof with respect to the bending portion being fixed onto the engine and the other side thereof with respect thereto being fixed onto the stopper fixing portion of the elastic member so as to grasp the elastic member between both sides of the stopper. 
   The above-described object can also be achieved by providing a vibration damping apparatus for supporting an engine on a vehicular body, comprising: an elastic member to damp a vibration developed from the engine; a second engine support member integrated with a stopper, the stopper being brought in contact with the elastic member to limit a transmission of a fluctuation developed on the engine therethrough and the second engine support member being interposed between the engine and the elastic member; and a vehicular body support member integrated with the elastic member to fix the elastic member on the vehicular body, the elastic member including a stopper fixing portion to fix the stopper integrated with the second engine support member thereon and placed on an opposing position to a position thereof faced toward the engine and the stopper including a bending portion via which the stopper is fixed onto the stopper fixing portion of the elastic member 
   This summary of the invention does not necessarily describe all necessary features so that the invention may also be a sub-combination of these described features. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIGS. 1A and 1B  are a side view and a cross sectional view of a vibration damping apparatus for supporting an engine on a vehicular body in a first preferred embodiment according to the present invention,  FIG. 1B  being the cross sectional view cut away along a line of A—A in  FIG. 1A . 
       FIG. 2  is a partially cross sectional view of an essential part of the vibration damping apparatus in the first embodiment shown in  FIGS. 1A and 1B  in the same way as cutting along a line of A—A shown in  FIG. 1B . 
       FIG. 3  is a partial cross sectional view of the essential part of the vibration damping apparatus in a second preferred embodiment according to the present invention at the same position as shown in  FIG. 2 . 
       FIG. 4  is a model view of an essential part of the vibration damping apparatus in the second preferred embodiment according to the present invention shown in  FIG. 3 . 
       FIG. 5  is a model view of the essential part of the vibration damping apparatus in the first embodiment shown in  FIGS. 1A and 1B  and  FIG. 2 . 
       FIG. 6  is a partially cross sectional view of the vibration damping apparatus in a third preferred embodiment according to the present invention at the same position as shown in  FIG. 2 . 
       FIG. 7  is a model view of the essential part of a previously proposed vibration damping apparatus described in the BACKGROUND OF THE INVENTION as a comparative example with the model view shown in  FIG. 4 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Reference will hereinafter be made to the drawings in order to facilitate a better understanding of the present invention. 
     FIGS. 1A and 1B  show a first preferred embodiment of a vibration damping apparatus for supporting an engine on a vehicular body according to the present invention.  FIG. 1A  is a side view of the vibration damping apparatus in the first embodiment mounted in a vehicle.  FIG. 1B  is a cross sectional view of the vibration damping apparatus cut away along a line of A—A shown in  FIG. 1A . 
   In  FIGS. 1A and 1B , an, so-called, engine mount  1  (or vibration damping support device) is interposed between an engine support bracket  2  (namely, a first engine support member) and a vehicular body fixed bracket  8  (namely, a vehicular body side supporting member). In addition, a stopper  3  is provided, a rubber assembly  4  (or an elastic member), a bolt  5 , bolts  6  and  9 , and a vehicular body part  7  are provided. Engine support bracket  2  has one side engaged with engine via bolts (not shown in  FIGS. 1A and 1B ) to fix bracket  2  onto the engine and the other side engaged with engine mount  1  to be mounted onto the engine. Thus, engine support bracket  2  is interposed between the engine and engine mount  1  to serve as a bridge of a mutual coupling thereof. Vehicular body side part  7  is a vehicular body or a suspension member fixed on the vehicular body. Engine mount  1  is fixed by a bolt engagement onto the vehicular body side part  7  at a side thereof different from a side at which engine mount  1  is fixed onto bracket  2 . As described above, engine mount  1  provides a basic function of supporting a weight of the engine between bracket  2  connected to the engine and vehicular body side part  7 . On the other hand, engine mount  1  is roughly divided into stopper  3 , rubber assembly  4 , and vehicular body side fixed bracket  8 . Engine mount  1  is coupled to bracket  2  by means of bolts  5  and  6  via stopper  3 . Vehicular body side fixed bracket  8  integrated to rubber assembly  4  by means of an adhesion by vulcanization serves to fix engine mount  1  onto the vehicular body side part  7  by means of engagement of bolt  9 , as shown in  FIGS. 1A and 1B . 
     FIG. 2  shows an enlarged view of the cross sectional view of  FIG. 1B . 
   In  FIG. 2 , a reference numeral  10  denotes a rubber of rubber assembly  4  (an elastic body), a reference numeral  11  denotes a pipe, a reference numeral  12  denotes a reinforcement fitting, a reference numeral  13  denotes a bending portion (a first bending portion), a reference numeral  14  denotes a bending portion (a second bending portion), a reference numeral  15  denotes a welding nut (a first fixing portion), and a reference numeral  16  denotes a welding nut (a second fixing portion). Reference numerals  3   a  and  3   b  denote upper and lower iron plates constituting stopper  3  by the integration thereof. Rubber assembly  4  includes rubber  10 , pipe  11  integrated with rubber  10  by means of the adhesion by vulcanization, and reinforcement (metal) fitting  12 , as shown in  FIG. 2 . Pipe  11  is installed to hold an engagement axle force by means of the engagement with bolt  5 . Stopper  3  is constituted by iron plate  3   a  positioned so as to face with bracket  2  and bending portions  13  and  14  by means of a stamping, iron plate  3   b  positioned on a lower portion of iron plate  3   a  being integrated with iron plate  3   a  by means of a welding or so forth. Iron plate  3   b  constituting stopper  3  is bent through a right angle at a bending portion  13  and, thereafter, is fixed to an end surface of pipe  11  by means of the welding at an end portion opposite to a side at which iron plate  3   b  is fixed to iron plate  3   a  by means of the welding. In addition, iron plates  3   a  and  3   b  constituting stopper  3  are fixed to welding nut  15  equipped on bracket  2  by means of the engagement of bolt  5  with pipe  11  grasped between two iron plates  3   a  and  3   b.  Apart from welding nut  15 , bracket  2  is provided with another welding nut  16  to fix the mutually integrated iron plates  3   a  and  3   b  by means of the engagement of bolt  6  onto bracket  6 . 
   Next, an operation of the vibration damping apparatus in the first embodiment will be described below. In order to explain a bending moment acted upon a first bending portion  13 , suppose, herein, a case in which stopper  3  is fixed only at a single position of welding nut  15  onto bracket  2 , as shown in  FIG. 3 . This case is a second embodiment of the vibration damping apparatus according to the present invention. It is noted that, in  FIG. 3 , a reference numeral  17  denotes a bending portion of stopper  3  and corresponds to the bending portion bent at a position of reference numeral  14  described in the first embodiment in an opposite direction to the bent direction at the bending portion  14  in the first embodiment. 
   In order to discuss theoretically a bending moment acted upon bending portion  13 , in the second embodiment, the bending moment is supposed from a model view with stopper  3  supposed to be the beam as shown in  FIG. 4 . Suppose that a fixing portion at which stopper  3  is fixed onto welding nut  15  is a fixed end R 1 , a portion of stopper  3  opposite to fixed end R 1  at which stopper  3  is fixed to pipe  11  is a fixed end R 2 , bending portion  13  is a bending point B 1 , bending portion  17  is a bending point B 2 , a position in a midway through bending point B 1  and fixed end R 2  at which rubber  10  is contacted with stopper  8  is an input point P, and a force generated there at is an input F. Suppose, then, that input point P is positioned in a midway through bending point B 1  and fixed end R 2  and at a position dividing a distance from bending point B 1  to fixed end into distances L 1  and L 2 . Suppose that the bending moment acted upon bending point B 1  is M B1 . According to a formula of the beam in a field of a strength of materials, 
   
     
       
         
           
             
               
                 
                   
                     
                       
                         
                           M 
                           B1 
                         
                         = 
                         
                           F 
                           × 
                           
                             { 
                             
                               
                                 ( 
                                 
                                   L1 
                                   + 
                                   
                                     L2 
                                     2 
                                   
                                 
                                 ) 
                               
                               / 
                               
                                 
                                   ( 
                                   
                                     L1 
                                     + 
                                     L2 
                                   
                                   ) 
                                 
                                 2 
                               
                             
                             } 
                           
                         
                       
                     
                   
                   
                     
                       
                         = 
                         
                           F 
                           × 
                           L1 
                           × 
                           
                             
                               
                                 { 
                                 
                                   L2 
                                   / 
                                   
                                     ( 
                                     
                                       L1 
                                       + 
                                       L2 
                                     
                                     ) 
                                   
                                 
                                 } 
                               
                               2 
                             
                             . 
                           
                         
                       
                     
                   
                 
                 ⁢ 
                 
                   
 
                 
                 ⁢ 
                 
                   Notice 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   
                     
                       ( 
                       
                         
                           L2 
                           / 
                           L1 
                         
                         + 
                         L2 
                       
                       ) 
                     
                     . 
                   
                 
               
             
             
               
                 ( 
                 1 
                 ) 
               
             
           
         
       
     
   
   That is to say, {L 2 /(L 1 +L 2 )}&lt;1 - - - (2). Hence, according to equations (1) and (2), M B1 &lt;F×L 1  - - - (3). 
   On the other hand, in a case of the previously proposed vibration damping apparatus described in the BACKGROUND OF THE INVENTION, the structure of stopper  3  takes the structure that an input due to the hit of stopper at bending portion  13  is received at the cantilever.  FIG. 7  is a model view of the bending moment acted upon the bending portion in the same way as described in the first embodiment. A difference of the structure related to  FIG. 7  from  FIG. 4  related to the second embodiment is that the stopper  3  is not fixed on pipe  11 . Suppose that bending portion  13  is a bending point B, bending moment acted upon bending point B by means of input F is M B . 
   M B =F×L 1  - - - (4). From equations (3) and (4), it follows that M B1 &lt;M B  - - - (5). 
   Hence, it will be appreciated that bending moment M B1  acted upon bending point B 1  in the second embodiment is smaller than bending moment M B  acted upon bending point B in the case of the previously proposed vibration damping apparatus (stopper is the cantilever type). Furthermore, from equations (1) and (4), the following relationship can be introduced. M B1 /M B ={L 2 /(L 1 +L 2 )} 2  - - - (6). Hence, since M B1  becomes smaller than M B  in proportion to a square of a ratio of distance L 2 , it can be said that M B1  becomes smaller remarkably. If distance L 2 =L 1  (namely,input point F is positioned at a center between bending point B 1  and fixed end R 2 ), the following relationship (7) is present from equation (6). That is to say, M B1 /M B =¼ - - - (7). Hence, equation (7) can evidence that M B1  becomes greatly decreased. 
   Although, with reference to  FIG. 4 , bending moment acted upon bending portion  13  in response to input F has been described above, the result of discussion described above can equally be applied to the structure in the first embodiment in which the position to be discussed has the same structure. 
   Next, a reaction force R R1  with respect to input force F acted upon fixed end R 1  will be discussed with reference to  FIG. 4 . As appreciated from  FIG. 4 , reaction force R B2  having the same magnitude as reaction force R B1  is acted upon bending point B 2  due to a principle of action and reaction when a reaction force R B1  with respect to input F, a resultant reaction force R R1  acted upon fixed end R 1  due to a balance of force between bending point B 2  and fixed end R 1  is as follows: That is to say, R R1 =R B1 - - - (8). 
   Next, a reaction force developed on welding nut  15  of bracket  2  in the first embodiment shown in  FIG. 2  is considered from a model view as shown in  FIG. 5 . Suppose that a fixing portion of stopper  3  at which stopper  3  is fixed onto welding nut  16  is fixed end R 3  and bending portion  14  is a bending point B 2 . From a result of discussion I  FIG. 4 , R B2 =R B1  - - - (9). 
   Hence, suppose that bending point B 2  is placed at a position at which a distance between fixed ends R 1  and R 3  is divided into distances L 3  and L 4 . In addition, stopper  3  is assumed to be the beam. The whole vibration damping apparatus in the first embodiment can be thought to be a beam at both ends of which the beam is supported and which has bending point B 2  upon which reaction force R B1  is acted. Reaction force RR 1  acted upon fixed end R 1  from a formula of the beam in the field of the strength of materials is determined as follows: 
   
     
       
         
           
             
               
                 
                   
                     
                       
                         R 
                         R1 
                       
                       = 
                         
                       ⁢ 
                       
                         
                           R 
                           B1 
                         
                         × 
                         
                           { 
                           
                             
                               { 
                               
                                 
                                   L4 
                                   2 
                                 
                                 / 
                                 
                                   
                                     ( 
                                     
                                       L3 
                                       + 
                                       L4 
                                     
                                     ) 
                                   
                                   2 
                                 
                               
                               ] 
                             
                             × 
                             
                               { 
                               
                                 
                                   ( 
                                   
                                     
                                       3 
                                       × 
                                       L3 
                                     
                                     + 
                                     L4 
                                   
                                   ) 
                                 
                                 / 
                                 
                                   ( 
                                   
                                     L3 
                                     + 
                                     L4 
                                   
                                   ) 
                                 
                               
                               } 
                             
                           
                         
                       
                     
                   
                 
                 
                   
                     
                       = 
                         
                       ⁢ 
                       
                         
                           R 
                           B1 
                         
                         × 
                         
                           { 
                           
                             
                               ( 
                               
                                 
                                   3 
                                   × 
                                   L3 
                                   × 
                                   
                                     L4 
                                     2 
                                   
                                 
                                 + 
                                 
                                   L4 
                                   3 
                                 
                               
                               ) 
                             
                             / 
                             
                               
                                 ( 
                                 
                                   L3 
                                   + 
                                   L4 
                                 
                                 ) 
                               
                               3 
                             
                           
                           } 
                         
                       
                     
                   
                 
                 
                   
                     
                       = 
                         
                       ⁢ 
                       
                         
                           R 
                           B1 
                         
                         × 
                         
                           [ 
                           
                             
                               ( 
                               
                                 
                                   3 
                                   × 
                                   L3 
                                   × 
                                   
                                     L4 
                                     2 
                                   
                                 
                                 + 
                                 
                                   L4 
                                   3 
                                 
                               
                               ) 
                             
                             / 
                             
                               { 
                               
                                 
                                   ( 
                                   
                                     3 
                                     + 
                                     
                                       L3 
                                       × 
                                       L4 
                                     
                                     + 
                                     
                                       L4 
                                       3 
                                     
                                   
                                   ) 
                                 
                                 + 
                               
                             
                           
                         
                       
                     
                   
                 
                 
                   
                     
                       
                         
                             
                           ⁢ 
                           
                             ( 
                             
                               3 
                               + 
                               
                                 
                                   L3 
                                   2 
                                 
                                 × 
                                 L4 
                               
                               + 
                               
                                 L3 
                                 3 
                               
                             
                             ) 
                           
                           } 
                         
                         ] 
                       
                       . 
                     
                   
                 
               
             
             
               
                 ( 
                 10 
                 ) 
               
             
           
         
       
     
   
   Since (3×L 3   2 ×L 4 +L 3   3 )&gt;0, R R1 /R B2  is expressed as follows: that is to say, R R1 /R B1 =(3×L 3 ×L 4   2 +L 4   3 )+(3×L 3 ×L 4   2 +L 4   3)}&lt; 1 - - - (11). Hence, since R R1 &lt;R B1 , it will be appreciated from equations (8) and (11) that reaction force R R1  acted upon fixed end R 1  in the first embodiment becomes smaller than that in the second embodiment. 
   As described above, reaction force developed on welding nut  15  of bracket  2  can be reduced by installing fixing portion of stopper  3  at which stopper  3  is fixed onto welding nut  16  of bracket  2  at a position more approaching to the engine than bending portion  14 . 
   Next, a third preferred embodiment of the vibration damping apparatus according to the present invention will be described below with reference to  FIG. 6 . 
   In  FIG. 6 , stopper  3  is integrated with bracket. In  FIG. 6 , a reference numeral  18  denotes a stopper integrated bracket (second engine support member), a reference numeral  19  denotes engine mount (the vibration damping support device), a reference numeral  20  denotes the rubber assembly (elastic body portion), a reference numeral  21  denotes a fluid chamber in which a working fluid is filled, a reference numeral  22  denotes a pipe, and a reference numeral  23  denotes a bending portion. 
   It is noted that, although a fluid mount is described as engine mount  1  in  FIG. 6 , the present invention is applicable to the fluid mount. However, it is of course that the present invention is applicable to a rubber mount in which no fluid is sealed therein. A bending moment acted upon bending portion  23  of a stopper integrated bracket  18  has the same model view as each of the first and second embodiments (a force and a moment acted upon at a bending point B 1  through fixed end R 2  are the same) so that the force and moment are the same as those described in each of the first and second embodiments. However, in an operation in which engine mount  1  is fixed onto stopper integrated bracket  18 , use of stopper integrated bracket  18  permits an engagement operation with a provisional mount of rubber assembly  20  onto a portion of stopper of stopper integrated bracket  18  rubber assembly  20  fixed onto the stopper. Hence, it becomes unnecessary for an operator to continue to hold rubber assembly  20  with only one hand until such a fixing operation as an engagement operation of bolts. Consequently, the workability of the fixing portion can be improved. 
   It is noted that, in  FIGS. 2 and 3 , vehicular body support member  8  and vehicular body part  7  shown in  FIG. 1A  are omitted for explanation purpose of the essential part of the vibration damping apparatus and the structure in the second embodiment shown in  FIG. 3  is the same as that in the first embodiment shown in  FIG. 2  except stopper  3  and second fixing portion  16  of bracket  2 . 
   The entire contents of a Japanese Patent Application No. 2001-190672 (filed in Japan on Jun. 25, 2001) are herein incorporated by reference. The scope of the invention is defined with reference to the following claims.