Abstract:
A method of reproducing abnormal noise comprises: a step of starting an engine while buffer suppressing members for suppressing the buffer function of an engine mount are mounted on the engine mount which buffer-mounts on a vehicle body an engine for driving a vehicle and a shift lever for driving is maintained in a neutral position; and a step of opening and closing the accelerator of the engine while the shift lever for driving is maintained in a neutral position. In the method of reproducing abnormal noise, jigs are used.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a method of reproducing an abnormal noise which was produced in the passenger compartment of a vehicle in association with vibrations of the vehicle body while the vehicle is traveling, and a jig for use in the method. 
       BACKGROUND ART 
       [0002]    While a vehicle is traveling, its passenger compartment can sometimes make abnormal noises which are not supposed to be generated therein. Such abnormal noises include chatter (noise produced when vehicle body components or small parts are vibrated and brought into contact with each other when the engine vibrates) of the instrument panel, for example. When the vehicle manufacturer or car repair shop is asked to repair the vehicle to stop the chatter, the field service person diagnoses the vehicle while actually driving the vehicle in order to confirm how and where the noise is produced. Alternatively, the field service person puts the vehicle on a vibration exciter, forcibly vibrates the vehicle to reproduce the abnormal sound, confirms the position where it is generated, and diagnoses the vehicle (Japanese Patent No. 3885297). 
       SUMMARY OF INVENTION 
       [0003]    It is a highly troublesome task to actually drive the vehicle and reproduce the abnormal noise, and it suffers a limitation in that it requires a driving course. According to the process disclosed in Japanese Patent No. 3885297, it is necessary to provide a vibration exciter which needs a substantial equipment investment, and the cost of the vibration exciter itself and a space and expenses to install the vibration exciter are entailed. The diagnosis of the vehicle using the vibration exciter takes a lot of trouble including moving the vehicle to the vibration exciter, operating the vibration exciter, etc. 
         [0004]    The present invention has been made in view of the above problems. It is an object of the present invention to provide a method of reproducing an abnormal noise easily and at a low cost, and a jig for use in such a method. 
         [0005]    According to the present invention, there is provided a method of reproducing an abnormal noise produced in the passenger compartment of a vehicle in association with vibrations of a vehicle body thereof while the vehicle is traveling, comprising the steps of starting to operate an engine for propelling the vehicle while a damping limiting member for limiting a damping function of an engine mount is installed on the engine mount which supports the engine on the vehicle body in a damping fashion, and a gearshift lever is kept in a neutral position, and increasing the rotational speed of the engine while the gearshift lever is kept in the neutral position. 
         [0006]    According to the present invention, while the damping function of the engine mount is limited and the gearshift lever is kept in the neutral position, the engine is started to operate and the rotational speed thereof is increased. It is thus possible to transmit vibrations of the engine to the vehicle body, without damping them, while the vehicle is at rest. As a consequence, it is possible to reproduce an abnormal noise produced in the passenger compartment in association with the vibrations transmitted to the vehicle body. 
         [0007]    Consequently, while the vehicle, which a worker has been asked to repair to stop an abnormal noise, is held at rest in a facility such as a repair pit or the like without being actually run, it is possible for the worker or a judging device to confirm a location where an abnormal noise is produced, e.g., where and how chatter of an instrument panel or the like is produced. 
         [0008]    Once the damping limiting member is installed in place, it is possible to confirm the generation of an abnormal noise by adjusting the position of the gearshift lever, starting to operate the engine, and increasing the rotational speed thereof. Therefore, the worker can confirm the generation of an abnormal noise in a relatively simple process. 
         [0009]    The damping limiting member may comprise a support member fixed to the engine and the vehicle body at a position where the engine mount supports the engine in the damping fashion. Therefore, part of the vibrations that are transmitted from the engine to the engine mount is transmitted to the vehicle body through the support member in bypassing relation to the engine mount. Therefore, it is easy to reproduce an abnormal sound associated with the vibrations that were generated in the passenger compartment while the vehicle was traveling. The process can easily be performed because it is only necessary to fix the support member depending on the position of the engine mount. 
         [0010]    The support member may support the engine selectively in a rigidly fixed mode and a loosely fixed mode for adjusting the magnitude of the vibrations. It is thus possible to change vibrations that are transmitted from the engine to the vehicle body. Accordingly, the range of noise reproducing inspections that can be handled can be increased. 
         [0011]    The support member may include a plurality of joint members connected by a threaded fastening mechanism, and the rigidly fixed mode and the loosely fixed mode may be adjusted by the strength of fastening by the threaded fastening mechanism. 
         [0012]    The engine mount may be fixed to the engine and the vehicle body by a threaded fastening mechanism, and the support member may be fixed to the engine and the vehicle body by the threaded fastening mechanism which is shared by the engine mount. According to the present invention, the support member can be fastened at a position where the engine mount is fixed to the engine and the vehicle body, by the threaded fastening mechanism that is shared by the engine mount (the support member and the engine mount are fastened together). With the support member and the engine mount being fastened together at the two locations, it is possible to cancel the damping function of the engine mount and transmit vibrations of the engine to the vehicle body, vibrating the vehicle body. It is thus possible with a simple arrangement to reproduce and confirm an abnormal noise that is produced in association with the vibrations of the vehicle body. 
         [0013]    According to the present invention, there is also provided a jig for canceling the damping function of an engine mount, comprising a support member fixed to the engine and the vehicle body at a position where the engine mount supports the engine in the damping fashion, wherein the support member comprises a jig comprising a first flange held in abutment against an engine-fixed portion of the engine mount which is fixed to the engine and fixed to the engine by a first threaded fastening mechanism which is shared by the engine-fixed portion, a second flange held in abutment against a vehicle-body-fixed portion of the engine mount which is fixed to the vehicle body and fixed to a member of the vehicle body by a second threaded fastening mechanism which is shared by the vehicle-body-fixed portion, and a rigid body connecting the first flange and the second flange to each other. 
         [0014]    According to the present invention, the first flange can be fastened to the engine-fixed portion of the engine mount by the first threaded fastening mechanism, and the second flange can be fastened to the vehicle-body-fixed portion of the engine mount by the second threaded fastening mechanism. With the support member and the engine mount being fastened together at the two locations, it is possible to cancel the damping function of the engine mount and transmit vibrations of the engine to the vehicle body, vibrating the vehicle body. It is thus possible with a simple arrangement to reproduce and confirm an abnormal noise that is produced in association with the vibrations of the vehicle body. 
         [0015]    The support member may include two installing rigid links each having a first flange installed on an engine side or vehicle body side of the engine mount and a second flange perpendicular to the first flange, and a plurality of connecting rigid links each having a third flange and a fourth flange which are displaced from each other along longitudinal directions and angularly spaced from each other by 90 degrees about a hypothetical axis along the longitudinal directions, wherein the connecting rigid links may be disposed between the two installing rigid links, and the angles between the connecting rigid links that are connected to each other may be adjusted to place the first flange of one of the two installing rigid links at a position where the engine side of the engine mount is installed and to place the first flange of the other installing rigid link at a position where the vehicle body side of aid engine mount is installed. 
         [0016]    With the above arrangement, the angles between the connecting rigid links that are connected to each other are adjusted to place the first flange of one of the two installing rigid links at a position where the engine side of the engine mount is installed and to place the first flange of the other installing rigid link at a position where the vehicle body side of aid engine mount is installed. Therefore, even in a plurality of situations where the engine mount is installed on the engine and the vehicle body at positions that are not in the same plane (e.g., if the engine mount is installed on the engine and the vehicle body at different angles or is disposed at different heightwise positions on the engine and the vehicle body), it is possible with the single jig to cancel the damping function of the engine mount and transmit vibrations of the engine to the vehicle body. As a consequence, it is possible with the single jig to perform an inspection to reproduce an abnormal noise with a plurality of vehicle types. 
         [0017]    The jig may further comprise a plurality of length adjusting rigid links each having a fifth flange and a sixth flange which are of a flat shape as a whole, are displaced from each other in the longitudinal directions, and extend parallel to each other, wherein at least two of the fifth flanges and the sixth flanges of the length adjusting rigid links may be connected to the second flanges of the installing rigid links or the third flanges or the fourth flanges of the connecting rigid links, and the connecting rigid links and the length adjusting rigid links may be disposed in a combination between the two installing rigid links. 
         [0018]    Since the length adjusting rigid links are of a flat shape as a whole, they can be manufactured more easily than the connecting rigid links that are of a twisted structure. Therefore, the length adjusting rigid links can be manufactured less costly than the connecting rigid links. With the length adjusting rigid links being combined with the connecting rigid links, the jig can be manufactured inexpensively. 
         [0019]    Each of the second through sixth flanges may be fixed in position by a bolt through a washer for adjusting the fastening strength of the bolt. By adjusting the fastening strength with the washer, it is possible to adjust the manner in which vibrations are transmitted from the engine to the vehicle body. Accordingly, the range of inspections for reproducing an abnormal noise can be increased. 
         [0020]    Alternatively, the support member may include at least five rigid links, each having holes defined in respective opposite ends thereof, interconnected by a threaded fastening mechanism, wherein each of two of the rigid links may comprise a bent rigid link having a first flange having a first hole defined therein and extending in longitudinal directions, and a second flange having a second hole defined therein and extending widthwise directions perpendicular to the first flange, each of at least other two of the rigid links may comprise a twisted rigid link having a third flange having a third hole defined therein and extending in longitudinal directions, and a fourth flange having a fourth hole defined therein and extending in the longitudinal directions, the third hole and the fourth hole being in twisted positional relationship, the bent rigid links may be disposed respectively at opposite ends of the jig, and the second flanges of the bent rigid links and the third flanges of the twisted rigid links may be interconnected at twisted junctions which are disposed in at least one and other ends of the jig. 
         [0021]    With the above arrangement, the jig has on its opposite sides twisted junctions where the bent rigid links and the twisted rigid links are connected to each other. In the twisted junctions, two of X, Y, Z axes can be adjusted. In addition, the three axes can also be adjusted if the relative positions of the twisted junctions are adjusted using at least one rigid link interconnecting the twisted junctions, for example. Therefore, even if the first hole of the bent rigid link on the engine and the first hole of the bent rigid link on the vehicle body are in twisted positional relationship, it is possible to connect the engine and the vehicle body to each other to transmit the vibrations from the engine to the vehicle body by adjusting the orientation of the twisted rigid links. As a consequence, it is possible with the single jig to perform an inspection to reproduce an abnormal noise with a plurality of vehicle types. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0022]      FIG. 1  is a perspective view of a jig according to a first embodiment of the present invention; 
           [0023]      FIG. 2  is a view showing an engine compartment of a vehicle with an engine hood removed; 
           [0024]      FIG. 3  is a perspective view of a side engine mount and its periphery; 
           [0025]      FIG. 4  is a flowchart of a working sequence to be followed by a worker to reproduce an abnormal noise using the jig according to the first embodiment; 
           [0026]      FIG. 5  is a flowchart of a sequence to be followed by the worker to install the jig; 
           [0027]      FIG. 6  is a view showing the manner in which the jig according to the first embodiment is to be installed; 
           [0028]      FIG. 7  is a view showing a state in which the jig according to the first embodiment is installed; 
           [0029]      FIG. 8  is a perspective view of a jig according to a second embodiment of the present invention; 
           [0030]      FIG. 9  is a perspective view of a first link of the jig according to the second embodiment; 
           [0031]      FIG. 10  is a perspective view of a second link of the jig according to the second embodiment; 
           [0032]      FIG. 11  is a perspective view of a bolt and a washer of the jig according to the second embodiment; 
           [0033]      FIG. 12  is a perspective view of a jig according to a third embodiment of the present invention; 
           [0034]      FIG. 13  is a perspective view of a third link of the jig according to the third embodiment; 
           [0035]      FIG. 14  is a perspective view of a fourth link of the jig according to the third embodiment; and 
           [0036]      FIG. 15  is a perspective view of a modification of the jig according to the third embodiment. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
     A. First Embodiment  
     1. Arrangement of Jig  10 : 
     (1) Overview 
       [0037]      FIG. 1  is a perspective view of a jig  10  according to a first embodiment of the present invention. The jig  10  serves to cancel (inhibit) the damping function of an engine mount. It is possible with the jig  10  to confirm the reproduction of an abnormal noise that is produced in the passenger compartment of a vehicle in association with vibrations of the vehicle body while the vehicle is traveling. 
         [0038]    As shown in  FIG. 1 , the jig  10  has a first flange  12  on an end thereof with a first hole  14  defined therein and a second flange  16  on the other end thereof with a second hole  18  defined therein. The jig  10  also has a connector  20  disposed between the first flange  12  and the second flange  16 . 
       (2) Arrangement of Engine and its Periphery 
       [0039]    Prior to describing how to use the jig  10 , the arrangement of the engine of the vehicle and its periphery will be described first. 
         [0040]      FIG. 2  is a view showing an engine compartment  32  of a vehicle  30  with an engine hood removed. An engine  34  is disposed substantially centrally in the engine compartment  32 . The engine  34  is supported by components of the vehicle body, such as frames, etc., not shown, through a plurality of engine mounts. 
         [0041]    In  FIG. 2 , a side engine mount  36  (hereinafter also referred to as “engine mount  36 ” or “mount  36 ”) is disposed on the left side of the engine  34  (on the right side as viewed from the driver seat). The engine mount comprises an elastic member of rubber or the like, and has a function to absorb vibrations produced by the engine  34  (damping function). For the structure of the engine mount, reference should be made to Japanese Laid-Open Patent Publication No. 2003-019909, for example. 
         [0042]      FIG. 3  is a perspective view of the side engine mount  36  and its periphery. The mount  36  is fixed to a bracket  38  of the engine  34  by a bolt  40 , and is also fixed to a member  46  of a vehicle body by bolts  42 ,  44 . The bracket  38  has two holes (not shown), one of which receives a screw  48  inserted therein that extends from a member  50  of the engine  34 , with a nut  52  threaded over the screw  48 . A bolt  54  extends through the other hole and is threaded in a threaded hole defined in the member  50 . The bracket  38  is thus fixed to the engine  34 . 
       2. How to Use the Jig  10  (Method of Reproducing an Abnormal Noise): 
       [0043]      FIG. 4  is a flowchart of a working sequence to be followed by a worker to reproduce an abnormal noise using the jig  10 . 
         [0044]    In step S 1 , the worker confirms that the engine  34  has shut down. If the engine  34  has not shut down, the worker shuts down the engine  34 . 
         [0045]    In step S 2 , the worker installs the jig  10 .  FIG. 5  is a flowchart of a sequence to be followed by the worker to install the jig  10 . 
         [0046]    In step S 11 , the worker removes the bolt  44  from the vehicle body. In step S 12 , the worker removes the nut  52  from the engine  34 . In step S 13 , the worker places the jig  10  so as to extend between the engine  34  and the vehicle body (see  FIG. 6 ). 
         [0047]    In step S 14 , the worker tightens the nut  52  on the engine  34 , fastening together the first flange  12  of the jig  10  and the bracket  38  which supports the engine mount  36  (fastening them together). 
         [0048]    In step S 15 , the worker tightens a dedicated bolt  56 , instead of the bolt  44  removed from the vehicle body, fastening together the second flange  16  of the jig  10  and the member  46  of the engine mount  36  of the vehicle body (fastening them together). The dedicated bolt  56  is of a sufficient length to fasten the jig  10  and the engine mount to each other (e.g., longer than the bolt  44  by the thickness of the jig  10 ). If the bolt  44  is of a sufficient length to fasten the jig  10  and the engine mount  36  to each other, then the bolt  44  may be used. 
         [0049]    In step S 3  in  FIG. 4 , the worker confirms that the gearshift lever (not shown) of the vehicle  30  is in a neutral position. The neutral position refers to a neutral gear position and a parking position. If the gearshift lever is not in the neutral position, then the worker moves the gearshift lever to the neutral position. 
         [0050]    In step S 4 , the worker turns on an ignition switch (IGSW), not shown, to start operating the engine  34 . In step S 5 , while keeping the gearshift lever in the neutral position, the worker depresses the accelerator pedal to increase the rotational speed of the engine  34 . Since the engine  34  and the vehicle body are interconnected by the jig  10 , vibrations from the engine  34  are transmitted through the jig  10  to the vehicle body in bypassing relation to the engine mount  36 . Therefore, more vibrations are transmitted to the vehicle body. As a result, the vehicle body is violently vibrated though the vehicle  30  is at rest. 
         [0051]    In step S 6 , the worker judges whether an abnormal sound is being produced in the passenger compartment by the vibrations from the engine  34 . If an abnormal sound is being produced (S 6 : YES), then the worker confirms where and how the abnormal sound is produced and repairs the causal location. If an abnormal sound is not being produced (S 6 : NO) or after step S 7 , the worker turns off the IGSW to stop operating the engine  34  in step S 8 . In step S 9 , the worker removes the jig  10 , and the puts the vehicle  30  back into its original state. 
       3. Advantages of the First Embodiment 
       [0052]    According to the first embodiment, as described above, while limiting the damping function of the engine mount  36  with the jig  10  and keeping the gearshift lever in the neutral position, the worker starts operating the engine  34  and operates the accelerator pedal. It is thus possible to transmit vibrations of the engine  34  to the vehicle body, without damping them, while the vehicle  30  is at rest. As a consequence, it is possible to reproduce an abnormal noise produced in the passenger compartment in association with the vibrations transmitted to the vehicle body. 
         [0053]    Consequently, while the vehicle  30 , which the worker has been asked to repair to stop an abnormal noise, is held at rest in a facility such as a repair pit or the like without being actually run, it is possible for the worker or a judging device to confirm a location where an abnormal noise is produced, e.g., where and how chatter of an instrument panel or the like is produced. 
         [0054]    Once the jig  10  is installed in place, it is possible to confirm the generation of an abnormal noise by adjusting the position of the gearshift lever, starting to operate the engine  34 , and opening and closing the accelerator. Therefore, the worker can confirm the generation of an abnormal noise in a relatively simple process. 
         [0055]    According to the first embodiment, the jig  10  is fixed to the engine  34  and the vehicle body at a position where the engine mount  36  supports the engine  34  in a damping fashion (see  FIG. 7 ). Therefore, part of the vibrations that are transmitted from the engine  34  to the engine mount  36  is transmitted to the vehicle body through the jig in bypassing relation to the engine mount  36 . Therefore, it is easy to reproduce an abnormal sound associated with the vibrations that were generated in the passenger compartment while the vehicle  30  was traveling. The process can easily be performed because it is only necessary to fix the jig  10  depending on the position of the engine mount  36 . 
         [0056]    According to the first embodiment, the engine mount  36  is fixed to the engine  34  by the screw  48  and the nut  52  and to the vehicle body by the dedicated bolt  56  (or the bolt  44 ). The jig  10  is fixed to the engine  34  by the screw  48  and the nut  52  that are shared by the engine mount  36 , and to the vehicle body by the dedicated bolt  56  (or the bolt  44 ) that is shared by the engine mount  36 . Therefore, the jig  10  and the engine mount  36  are fastened together at a position where the engine mount  36  is fixed to the engine  34  and the vehicle body. With the jig  10  and the engine mount  36  being fastened together at the two locations, it is possible to cancel the damping function of the engine mount  36  and transmit vibrations of the engine  34  to the vehicle body, vibrating the vehicle body. It is thus possible with a simple arrangement to reproduce and confirm an abnormal noise that is produced in association with the vibrations of the vehicle body. 
       B. Second Embodiment 
     1. Arrangement of Jig  100  (Differences With the First Embodiment) 
       [0057]      FIG. 8  is a perspective view of a jig  100  according to a second embodiment of the present invention.  FIG. 9  is a perspective view of a first link  102  of the jig  100 .  FIG. 10  is a perspective view of a second link  104  of the jig  100 .  FIG. 11  is a perspective view of a bolt  106  and a washer  108  of the jig  100 . As with the jig  10  according to the first embodiment, the jig  100  serves to cancel (inhibit) the damping function of an engine mount such as the side engine mount  36  or the like. It is possible with the jig  100  to confirm the reproduction of an abnormal noise that is produced in the passenger compartment of the vehicle  30  in association with vibrations of the vehicle body while the vehicle  30  is traveling. 
         [0058]    The jig  100  is used in basically the same procedure as the jig  10  according to the first embodiment. However, since the jig  100  can change its configuration unlike the jig  10 , it can transmit vibrations from the engine  34  to the vehicle body with a plurality of vehicle types and a plurality of regions. As a result, it is possible with the single jig  100  to perform an inspection to reproduce an abnormal noise with a plurality of vehicle types and a plurality of regions. 
         [0059]    As shown in  FIGS. 8 through 11 , the jig  100  comprises four types of members. Specifically, the jig  100  has first links  102  (installing rigid links, bent rigid links) disposed respectively at opposite ends thereof, a plurality of second links  104  (connecting rigid links, twisted rigid links) interconnecting the first links  102 , bolts  106  connecting and securing the first links  102  and the second links  104  or connecting and securing the second links  104 , and washers  108  for adjusting the fastening strength of the bolts  106 . 
         [0060]    Each of the first links  102  is a member corresponding to the first flange  12  or the second flange  16  of the jig  10  according to the first embodiment, and comprises a rigid body having a first flange  110  for being installed on an engine mount (e.g., the side engine mount  36  according to the first embodiment) and a second flange  112  extending perpendicularly to the first flange  110 . The first flange  110  has a first hole  114  defined therein for insertion of a bolt (e.g., the dedicated bolt  56  according to the first embodiment) or a screw (e.g., the screw  48  according to the first embodiment) therethrough. The second flange  112  has a second hole  116  defined therein for insertion of the bolt  106  therethrough. 
         [0061]    Each of the second links  104  comprises a rigid body having a third flange  120  and a fourth flange  122  which are displaced from each other along the longitudinal directions (the X directions in  FIG. 10 ) and angularly spaced from each other by 90 degrees about a hypothetical axis Av along the longitudinal directions. Stated otherwise, when one of the third flange  120  and the fourth flange  122  is turned through 90 degrees about the hypothetical axis Av, they are held in phase with each other in the X-axis directions. The third flange  120  has an unthreaded third hole  124  defined therein, and the fourth flange  122  has a threaded fourth hole  126  defined therein. 
         [0062]    As shown in  FIG. 8 , in each of the junctions between the first links  102  and the second links  104 , the second flange  112  of the first link  102  and the third flange  120  of the second link  104  are connected to each other. In each of the junctions between the second links  104 , basically, the third flange  120  of one of the second links  104  and the fourth flange  122  of the other second link  104  are connected to each other, with the fourth flange  122  being positioned at the head of the bolt  106 . With the links being thus disposed, it is possible to adjust the angles between one of the second links  104  and the other thereof which are connected to each other. 
       2. Operation and Advantages of the Jig  100   
       [0063]    With the jig  100  according to the second embodiment, the angles between the second links  104  that are connected to each other are adjusted to place the first flange  110  of one of the two first links  102  at the position where the engine mount  36  is installed on the engine  34  (e.g., the position of the screw  48  and the nut  52  in the first embodiment) and to place the first flange  110  of the other first link  102  at the position where the engine mount  36  is installed on the vehicle body (e.g., the position of the bolt  44  according to the first embodiment). Therefore, even in a plurality of situations where the engine mount  36  is installed on the engine  34  and the vehicle body at positions that are not in the same plane (e.g., if the two bolts inserted in the first holes  114  extend at different angles or are disposed at different heightwise positions), it is possible with the single jig  100  to cancel the damping function of the engine mount  36  and transmit vibrations of the engine  34  to the vehicle body. As a consequence, it is possible with the single jig  100  to perform an inspection to reproduce an abnormal noise with a plurality of vehicle types and a plurality of positions. 
         [0064]    According to the second embodiment, each of the second flanges  112 , the third flanges  120 , and the fourth flanges  122  is fastened in position by the bolt  106  through the washer  108  for adjusting the fastening strength. By adjusting the fastening strength with the washer  108 , it is possible to adjust the manner in which vibrations are transmitted from the engine  34  to the vehicle body. Accordingly, the range of inspections for reproducing an abnormal noise can be increased. 
         [0065]    According to the second embodiment, as shown in  FIG. 8 , the jig  100  has on its opposite sides twisted junctions where the first links  102  and the second links  104  are connected to each other. In the twisted junctions, two of X, Y, Z axes can be adjusted. In addition, the three axes can also be adjusted if the relative positions of the twisted junctions are adjusted using one or more of the second links  104  interconnecting the twisted junctions. Therefore, even if the first hole  114  of one of the two first links  102  and the first hole  114  of the other first link  102  are in twisted positional relationship, it is possible to connect the engine  34  and the vehicle body to each other to transmit the vibrations from the engine  34  to the vehicle body by adjusting the orientation of the second links  104 . As a consequence, it is possible with the single jig  100  to perform an inspection to reproduce an abnormal noise with a plurality of vehicle types or positions. 
       C. Third Embodiment 
     1. Arrangement of Jig  150  (Differences With the Second Embodiment) 
       [0066]      FIG. 12  is a perspective view of a jig  150  according to a third embodiment of the present invention.  FIG. 13  is a perspective view of a third link  152  of the jig  150 .  FIG. 14  is a perspective view of a fourth link  154  of the jig  150 . As with the jig  100  according to the second embodiment, the jig  150  serves to cancel (inhibit) the damping function of an engine mount such as the side engine mount  36  or the like. It is possible with the jig  150  to confirm the reproduction of an abnormal noise that is produced in the passenger compartment of the vehicle  30  in association with vibrations of the vehicle body while the vehicle  30  is traveling. 
         [0067]    The jig  150  is used in basically the same procedure as the jig  100  according to the second embodiment. However, unlike the jig  100  according to the second embodiment, the jig  150  additionally includes third links  152  and fourth links  154  (length adjusting rigid links). 
         [0068]    As shown in  FIGS. 12 through 14 , the jig  150  comprises six types of members. Specifically, the jig  150  has third links  152  and fourth links  154  in addition to the first links  102 , the second links  104 , the bolts  106 , and the washers  108  as with the second embodiment. 
         [0069]    Each of the third links  152  is of a flat shape as a whole, and comprises a rigid body having a fifth flange  156  and a sixth flange  158  which are displaced from each other along the longitudinal directions and extend parallel to each other. The fifth flange  156  and the sixth flange  158  of each of the third links  152  have an unthreaded fifth hole  160  and an unthreaded sixth hole  162  defined respectively therein. Since the third links  152  are axisymmetric, the distinction between fifth flange  156  and the sixth flange  158  and the distinction between the fifth hole  160  and the sixth hole  162  are merely expedient. 
         [0070]    Similarly, each of the fourth links  154  is of a flat shape as a whole, and comprises a rigid body having a seventh flange  164  and an eighth flange  166  which are displaced from each other along the longitudinal directions and extend parallel to each other. The seventh flange  164  and the eighth flange  166  of each of the fourth links  154  have a threaded seventh hole  168  and a threaded eighth hole  170  defined respectively therein. Since the fourth links  154  are axisymmetric, the distinction between seventh flange  164  and the eighth flange  166  and the distinction between the seventh hole  168  and the eighth hole  170  are merely expedient. 
       2. Operation and Advantages of the Jig  150   
       [0071]    The jig  150  according to the third embodiment has the same operation and advantages as the jig  100  according to the second embodiment. In addition, the jig  150  according to the third embodiment offers the following advantages: Since the third links  152  and the fourth links  154  are of a flat shape as a whole, they can be manufactured more easily than the second links  104  that are of a twisted structure. Therefore, the third links  152  and the fourth links  154  can be manufactured less costly than the second links  104 . With the third links  152  and the fourth links  154  being combined with the second links  104 , the jig  150  can be manufactured inexpensively compared with the jig  100 . 
       D. Modification 
       [0072]    The present invention is not limited to the above embodiments, but may adopt various arrangements without departing from the scope of the invention. For example, the present invention may adopt the following arrangements: 
         [0073]    In the above embodiments, the jigs  10 ,  100 ,  150  are applied to the side engine mount  36 . However, the jigs  10 ,  100 ,  150  may be applied to other engine mounts. 
         [0074]    In the above embodiments, the screw  48  and the nut  52  are used as a threaded fastening mechanism on the engine  34 , and the bolt  44  is used as a threaded fastening mechanism on the vehicle body. However, the present invention is not limited to such a structure. A bolt and a nut may be used on the engine  34 , and a screw and a nut may be used on the vehicle body. 
         [0075]    In the third embodiment, the second links  104 , the third links  152 , and the fourth links  154  are alternately disposed ( 104  to  152  to  104  to  154  to  104  to . . . ). However, the present invention is not limited to such a structure. The second links  104 , the third links  152 , and the fourth links  154  may be arranged in a combination in a jig  200  shown in  FIG. 15 . 
         [0076]    In each of the above embodiments, many steps of the process for reproducing an abnormal noise are performed by the worker. However, the present invention is not limited to such a sequence. Some of the steps of the process may be performed by an apparatus such as a diagnostic apparatus or the like. For example, in each of the above embodiments, the worker judges whether an abnormal noise is produced or not. An abnormal noise may be automatically judged by the process disclosed in Japanese Patent No. 3885297. In such a case, the engine output control (rotational speed control) may be performed by an electronic control unit (ECU) which automatically controls a throttle valve, rather than the worker who operates the accelerator pedal.