Abstract:
A production line for vehicles of different models is disclosed, wherein vehicle bodies for ordinary automobiles and vehicle bodies for compact automobiles are incorporated on the same production line, and multiple components are installed. Two compact vehicle bodies are carried on a conveyance device which is designed for carrying a single ordinary vehicle body. The number of components of a compact automobile is approximately half the number of components of an ordinary automobile, and therefore compact automobiles can be produced efficiently without any downtime.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a line for producing vehicles of different models while conveyance devices carrying vehicle bodies thereon are conveyed along a conveyance line. 
       BACKGROUND OF THE INVENTION 
       [0002]    Choosing automobiles that match one&#39;s lifestyle is a recent trend, and a stronger demand exists for compact (small-sized) automobiles having a smaller occupant capacity (two to three people) in the same way as for ordinary (regular-sized) automobiles that have a regular occupant capacity (five people). 
         [0003]    Since compact automobiles have an occupant capacity of two to three people, they need only one row of seats, and the total length of the automobile can be shortened to approximately half the length of an ordinary automobile. 
         [0004]    A production line designated for compact automobiles must be newly prepared in order to manufacture the compact automobiles. However, the need to prepare a new production line designated for compact automobiles raises the equipment costs of production lines and poses an obstacle to keeping the costs of such compact automobiles low. 
         [0005]    Additionally, extra space must be ensured within the production factory in order to prepare a new production line designated for compact automobiles. 
         [0006]    One example of a production line is a mixed production line for producing vehicles of different models, such as sports cars or station wagons, as is disclosed in the Japanese Publication JP 63-013857 A or Japanese Patent No. 3008220. 
         [0007]    Sports cars, stations wagons, and other vehicle models each have different numbers of components. A mixed production line for producing vehicles with different numbers of components is provided with a bypass conveying line. 
         [0008]    For example, mixed production with vehicles having a small number of components is adjusted by causing vehicles having a large number of components to go through the bypass conveying line. 
         [0009]    It is possible to absorb the difference in the number of components by using a bypass production line because sports cars, station wagons, and other vehicles merely have small differences in the numbers of components. 
         [0010]    However, compact automobiles have approximately half the number of components of ordinary automobiles. Consequently, in the mixed production line disclosed in JP 63-13857 A, when compact automobiles are incorporated into an ordinary automobile production line, the number of steps for assembling a compact automobile is approximately half the number of steps for assembling an ordinary automobile. 
         [0011]    When the number of steps for assembling a compact automobile decreases by half, it is difficult to adequately absorb the difference in the number of components by using the bypass conveying line disclosed in JP 63-13857 A. In this case, the solution is to set the assembly operation time for compact automobiles in accordance with the assembly operation time for larger automobiles. 
         [0012]    Therefore, there is much idle time in the assembly operation for compact automobiles, and it is difficult to produce compact automobiles efficiently. 
       SUMMARY OF THE INVENTION 
       [0013]    It is therefore an object of the present invention to provide a production line for vehicles of different models that can produce compact automobiles more efficiently when compact automobiles having different numbers of components than ordinary automobiles are incorporated into an ordinary automobile production line. 
         [0014]    According to a first aspect of the present invention, there is provided a production line for vehicles of different models, including a plurality of conveying mechanisms for conveying along a conveying line respective conveyance devices with vehicle bodies carried thereon in such a manner as to allow components to be installed on the vehicle bodies, wherein each of the conveying devices is adapted to carry two of the vehicle bodies. 
         [0015]    Compact automobiles herein have approximately half the number of components of an ordinary automobile, for example. It is possible to form a single unit from the vehicle bodies of two compact automobiles in the production line by mounting two compact automobile vehicle bodies on a conveying hanger. 
         [0016]    Two unitized vehicle bodies have approximately the same number of components as an ordinary automobile, and the number of assembly steps is approximately the same as an ordinary automobile. Consequently, two unitized vehicle bodies can have the same number of assembly steps as the vehicle body of an ordinary automobile. Thereby, when the vehicle bodies of compact automobiles and ordinary automobiles are produced together, compact automobiles can be produced more efficiently without any idle time in the steps of assembling the compact automobiles. 
         [0017]    In the production line described above, it is preferred that in a state in which two vehicle bodies are mounted on a conveyance device, the total length of the two mounted vehicle bodies be equal to the maximum total length of an ordinary vehicle body that can be conveyed along the conveying line. Consequently, conveyance devices for mounting two vehicle bodies can be placed at the same intervals as conveyance devices for mounting one vehicle body of an ordinary automobile. Two unitized vehicle bodies can thereby be conveyed at the same intervals as vehicle bodies of ordinary automobiles, and compact automobiles can be produced more efficiently. 
         [0018]    In a state in which two vehicle bodies are mounted on a conveyance device, it is preferred that the total length of the two mounted vehicle bodies be less than the maximum total length of an ordinary vehicle body that can be conveyed along the conveying line. 
         [0019]    In a state in which two vehicle bodies are mounted on a conveyance device, it is preferred that each of the two mounted vehicle bodies is the body of a vehicle having an occupant capacity of two people. 
         [0020]    In a state in which two vehicle bodies are mounted on a conveyance device, it is preferred that the two mounted vehicle bodies be mounted on the conveyance device so that rear parts thereof face each other. 
         [0021]    According to a second aspect of the present invention, there is provided a production line for vehicles of different models, which comprises: a conveying line; and a plurality of conveyance devices adapted to be conveyed along the conveying line and designed to carry a single first vehicle body, wherein one of the conveyance devices is configured to carry two second vehicle bodies of a different model than the first vehicle body. 
         [0022]    The first vehicle body may, for example, be a vehicle body of an ordinary automobile according to the embodiments, and the second vehicle body may be a vehicle body of a compact automobile. The total length of two compact automobiles is approximately equal to the total length of one ordinary automobile. 
         [0023]    The conveyance device preferably has multiple brackets for supporting a first vehicle body or two second vehicle bodies in the anteroposterior direction of the mounted vehicles. Therefore, the conveyance device can support a single first vehicle body, and can also support two second vehicle bodies. 
         [0024]    According to a third aspect of the present invention, there is provided a method for producing vehicles of different models, comprising the steps of: conveying multiple conveyance devices, each of which is used for mounting a single first vehicle body, along a conveying line; and mounting two second vehicle bodies on each of the conveyance devices when the second vehicle bodies of a different model than the first vehicle body are incorporated into the conveying line. 
         [0025]    According to a fourth aspect of the present invention, there is provided a production line for vehicles of different models, comprising: a conveying line; a plurality of first conveyance devices conveyed along the conveying line and used for mounting a first vehicle body; and a sub-line whereby a plurality of second conveyance devices that are the same as the first conveyance devices and that carry second vehicle bodies are supplied to the conveying line with short intervals when the second vehicle bodies of a different model than the first vehicle body are incorporated and assembled in an array of the first vehicle bodies. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    Certain preferred embodiments of the present invention will be described in detail below, by way of example only, with reference to the accompanying drawings, in which: 
           [0027]      FIG. 1  is a side elevational view showing a compact automobile produced in a production line according to the present invention; 
           [0028]      FIG. 2  is a top plan view showing the compact automobile of  FIG. 1 ; 
           [0029]      FIG. 3  is a schematic view showing a production line for vehicles of different models according to a first embodiment of the present invention; 
           [0030]      FIG. 4  is a side elevational view showing an ordinary vehicle body placed on a conveyance device shown in  FIG. 3 ; 
           [0031]      FIG. 5  is a side elevational view showing two compact vehicle bodies placed on the conveyance device of  FIG. 3 ; 
           [0032]      FIG. 6  is a schematic view showing the step of painting ordinary vehicle bodies and compact vehicle bodies in the production line of  FIG. 3 ; 
           [0033]      FIG. 7  is a schematic view showing the step of installing engines, suspension systems and other components in ordinary vehicle bodies and compact vehicle bodies in the production line of  FIG. 3 ; 
           [0034]      FIG. 8  is a schematic view showing the step of assembling exterior and interior components in ordinary vehicle bodies and compact vehicle bodies in the production line of  FIG. 3 ; and 
           [0035]      FIG. 9  is a schematic top plan view showing the production line for vehicles of different models according to a second embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0036]    A first embodiment of the present invention will now be discussed with reference to  FIGS. 1 to 8 . As shown in  FIGS. 1 and 2 , a compact automobile  10  comprises an engine  13  disposed at the front of a vehicle body  11 , a right side door  14  disposed on the right side of the vehicle body  11 , a left side door  15  disposed on the left side of the vehicle body  11 , a driver seat  17  disposed on the right side within a passenger compartment  16 , a passenger seat  18  disposed on the left side within the passenger compartment  16 , left and right front wheels  21 ,  21  disposed at the front of the vehicle body  11 , and left and right rear wheels  22 ,  22  disposed at the rear of the vehicle body  11 . 
         [0037]    The compact automobile  10  is a vehicle having an occupant capacity of two people, including the driver seat  17  and the passenger seat  18 . 
         [0038]    The total length L 1  of the compact automobile  10  is approximately half the total length L 2  of an ordinary automobile  25  shown in  FIG. 3C . 
         [0039]    The first embodiment relates to a compact automobile  10  having an occupant capacity of two people, but this automobile may also have an occupant capacity of three people, in which case a center seat (not shown) is provided between the driver seat  17  and the passenger seat  18 , for example. 
         [0040]    Referring to  FIG. 3 , a vehicle production line  30  comprises a painting area  31  for painting a vehicle body  26  of the ordinary automobile  25  and the vehicle body  11  of the compact automobile  10 ; a drive system installation area  32  for installing drive systems composed of engines, suspension systems, and the like into the vehicle body  26  of the ordinary automobile  25  and the vehicle body  11  of the compact automobile  10 ; and an exterior and interior installation area  33  for installing side doors and seats in the vehicle body  26  of the ordinary automobile  25  and the vehicle body  11  of the compact automobile  10 . 
         [0041]    The vehicle production line  30  further comprises a first conveying mechanism  35  for conveying the vehicle body  26  of the ordinary automobile  25  and vehicle bodies  11 ,  11  of compact automobiles  10  in a suspended state; and a second conveying mechanism  36  for conveying the vehicle body  26  of the ordinary automobile  25  and vehicle bodies  11 ,  11  of compact automobiles  10  in a mounted state. 
         [0042]    In the exterior and interior installation area  33  shown in  FIG. 3C , after side doors and seats are installed in the vehicle body  26  of the ordinary automobile  25  and the vehicle body  11  of the compact automobile  10 , front wheels  21 ,  21  and rear wheels  22 ,  22  are installed in the vehicle body  26  of the ordinary automobile  25  and the vehicle body  11  of the compact automobile  10 , thereby completing the assembly steps of the ordinary automobile  25  and the compact automobile  10 . 
         [0043]    The first conveying mechanism  35  conveys the vehicle body  26  of the ordinary automobile  25  and the vehicle body  11  of the compact automobile  10  in a suspended state through the painting area  31 , and also conveys the vehicle body  26  of the ordinary automobile  25  and the vehicle body  11  of the compact automobile  10  in a suspended state through the drive system installation area  32  as shown in  FIG. 3B . 
         [0044]    The second conveying mechanism  36  conveys the vehicle body  26  of the ordinary automobile  25  and the vehicle body  11  of the compact automobile  10  in a mounted state on a belt conveyor through the exterior and interior installation area  33 . 
         [0045]      FIG. 4  shows the vehicle body  26  of an ordinary automobile mounted on the first conveying mechanism  35 , and  FIG. 5  shows vehicle bodies  11 ,  11  of compact automobiles mounted on the first conveying mechanism  35 . 
         [0046]    The first conveying mechanism  35  comprises a guide rail (conveying line)  41  provided above the painting area  31  and the drive system installation area  32  shown in  FIG. 3 , a carrier  42  moveably suspended from the guide rail  41 , a conveying hanger (conveying device)  43  provided to the suspended carrier  42 , and a moving device (not shown) for moving the carrier  42  along the guide rail  41 . 
         [0047]    The suspended carrier  42  is linked to the guide rail  41  via a support arm  45 . Rollers (not shown) are provided at the top end of the support arm  45 . The suspended carrier  42  is disposed to be movable along the guide rail  41  via the rollers. 
         [0048]    The conveying hanger  43  is composed of right and left front hanger frames  46 ,  47  provided at the front end of the carrier  42 , right and left rear hanger frames  48 ,  49  provided at the rear end of the carrier  42 , a right support  51  provided at the bottom ends of the right front hanger frame  46  and the right rear hanger frame  48 , and a left support  52  provided at the bottom ends of the left front hanger frame  47  and the left rear hanger frame  49 . 
         [0049]    The right and left front hanger frames  46 ,  47  are bilaterally symmetric, as are the right and left rear hanger frames  48 ,  49 . 
         [0050]    A first right bracket  51   a  is provided at the front end of the right support  51 , a second right bracket  51   b  is provided at the rear end, a third right bracket  51   c  is provided behind the first right bracket  51   a  (in proximity to the right front hanger frame  46 ), and a fourth right bracket  51   d  is provided in front of the second right bracket  51   b  (in proximity to the right rear hanger frame  48 ). 
         [0051]    A first left bracket  52   a  is provided at the front end of the left support  52 , a second left bracket  52   b  is provided at the rear end, a third left bracket  52   c  is provided behind the first left bracket  52   a  (in proximity to the left front hanger frame  47 ), and a fourth left bracket  52   d  is provided in front of the second left bracket  52   b  (in proximity to the left rear hanger frame  49 ). 
         [0052]    The right and left supports  51 ,  52  are bilaterally symmetrical, and the first through fourth right brackets  51   a  to  51   d,  as well as the first through fourth left brackets  52   a  to  52   d,  are also bilaterally symmetrical. 
         [0053]    One example of the aforementioned moving device is a setup in which the suspended carrier  42  is connected by a chain (not shown), and the chain is driven to move the suspended carrier  42  along the guide rail  41  as shown by the arrow. 
         [0054]    An example of mounting the vehicle body  26  of the ordinary automobile  25  on the conveyance device  43  will be described with reference to  FIG. 4 . The vehicle body  26  of the ordinary automobile  25  is hereinbelow referred to as a “ordinary vehicle body  26 .” 
         [0055]    The third right bracket  51 c of the right support  51  and the third left bracket  52   c  of the left support  52  bear the front part  26   a  of the ordinary vehicle body  26 . The fourth right bracket  51   d  of the right support  51  and the fourth left bracket  52   d  of the left support  52  bear the rear part  26   b  of the ordinary vehicle body  26 . The ordinary vehicle body  26  is mounted facing forward on the conveying hanger  43 . 
         [0056]    An example of mounting a vehicle body  11  of a compact automobile  10  on both the front half  43   a  and rear half  43   b  of the conveying hanger  43  will be described with reference to  FIG. 5 . Hereinbelow, the vehicle body  11  of the compact automobile  10  mounted facing forward on the front half  43   a  of the conveying hanger  43  is referred to as the “forward-facing compact vehicle body  11 ,” and the vehicle body  11  of the compact automobile  10  mounted facing backward on the rear half  43   b  of the conveying hanger  43  is referred to as the “backward-facing compact vehicle body  11 .” 
         [0057]    The first right bracket  51   a  of the right support  51  and the first left bracket  52   a  of the left support  52  bear the front part  11   a  of the forward-facing compact vehicle body  11 . The third right bracket  51   c  of the right support  51  and the third left bracket  52   c  of the left support  52  bear the rear part  11   b  of the forward-facing compact vehicle body  11 . The forward-facing compact vehicle body  11  is mounted facing forward on the front half  43   a  of the conveying hanger  43 . 
         [0058]    The second right bracket  51   b  of the right support  51  and the second left bracket  52   b  of the left support  52  bear the front part  11   a  of the backward-facing compact vehicle body  11 . The fourth right bracket  51   d  of the right support  51  and the fourth left bracket  52   d  of the left support  52  bear the rear part  11   b  of the backward-facing compact vehicle body  11 . The backward-facing compact vehicle body  11  is mounted facing backward on the rear half  43   b  of the conveying hanger  43 . 
         [0059]    Thus, the forward-facing compact vehicle body  11  is mounted facing forward on the front half  43   a  of the conveying hanger  43 , and the backward-facing compact vehicle body  11  is mounted facing backward on the rear half  43   b  of the conveying hanger  43 , whereby two compact automobiles  10  are mounted on a single conveying hanger  43 . 
         [0060]    The compact automobiles  10  shown in  FIG. 5  have a total length L 1  ( FIG. 3 ), and the ordinary automobile  25  shown in  FIG. 3  has a total length L 2  ( FIG. 2 ). The total length L 1  is reduced to about half of the total length L 2 . 
         [0061]    For the sake of convenience, the total length L 2  of the ordinary automobile  25  is assumed to be the maximum total length of a vehicle body that can be conveyed along the guide rail  41 . 
         [0062]    With the two compact vehicle bodies  11  mounted on the conveying hanger  43 , the total length L 3  of the two mounted compact vehicle bodies  11  is either approximately equal to the maximum total length L 2  of a vehicle body that can be conveyed along the guide rail  41 , or is kept smaller than the maximum total length L 2 . 
         [0063]    In the first embodiment, the total length L 3  of the two mounted compact vehicle bodies  11  is described as being approximately equal to the maximum total length L 2 . 
         [0064]    The following is a description, made with reference to  FIGS. 6 through 8 , of an example of assembly in which four compact vehicle bodies  11  are incorporated among multiple ordinary vehicle bodies  26  in the vehicle production line  30 . 
         [0065]    Two compact vehicle bodies  11  are formed into a single unit by being mounted on a conveying hanger  43 , as shown in  FIG. 6 . The total length L 3  of two unitized compact vehicle bodies  11  is approximately equal to the total length L 2  (maximum total length L 2 ) of an ordinary automobile  25 . 
         [0066]    Consequently, in the painting area  31 , both the conveyance devices  43  on which two compact vehicle bodies  11  are mounted as a single unit, and the conveying hangers  43  on which ordinary vehicle bodies  26  are mounted can be moved along the guide rail  41  at equal intervals P 1  in the direction of the arrow. 
         [0067]    The surface area of a compact vehicle body  11  is approximately half the surface area of an ordinary vehicle body  26 . Therefore, the surface area of two unitized compact vehicle bodies  11  is approximately equal to the surface area of an ordinary vehicle body  26 . 
         [0068]    Consequently, the time required to paint two unitized compact vehicle bodies  11  can be approximately equal to the time required to paint an ordinary vehicle body  26 . 
         [0069]    Thus, two unitized compact vehicle bodies  11  can be conveyed at the same interval P 1  as an ordinary vehicle body  26 , and the painting time for a single unit of two compact vehicle bodies  11  can be approximately equal to the painting time for an ordinary vehicle body  26 . Consequently, when two unitized compact vehicle bodies  11  are incorporated among ordinary vehicle bodies  26  and painted, the compact vehicle bodies  11  can be painted in approximately the same time as an ordinary vehicle body  26 . The compact vehicle bodies  11  can thereby be painted efficiently. 
         [0070]      FIG. 7  shows the steps of installing engines, suspension systems, and other components in ordinary vehicle bodies and compact vehicle bodies. 
         [0071]    In the drive system installation area  32 , the ordinary vehicle bodies  26  and the compact vehicle bodies  11  are conveyed by conveying hangers  43 , similar to the painting area  31 . In the drive system installation area  32 , conveying hangers  43  on which two unitized compact vehicle bodies  11  are mounted, as well as conveying hangers  43  on which a single ordinary vehicle body  26  is mounted, are moved along the guide rail  41  at equal intervals P 1  in the direction of the arrow. 
         [0072]    In the drive system installation area  32 , components that include engines  61 , front and rear suspension systems  62 ,  63 , and the like are installed in the ordinary vehicle bodies  26 . 
         [0073]    Similarly, components that include engines  13 , front and rear suspension systems  65 ,  66 , and the like are installed in the compact vehicle bodies  11 . 
         [0074]    The engines  13  of the compact vehicle bodies  11  are smaller and lighter than the engines  61  of the ordinary vehicle bodies  26 . The front and rear suspension systems  65 ,  66  of the compact vehicle bodies  11  are smaller and lighter than the front and rear suspension systems  62 ,  63  of the ordinary vehicle bodies  26 . 
         [0075]    Consequently, the time required to install the engines  13 , front and rear suspension systems  65 ,  66 , and the like in two of the unitized compact vehicle bodies  11  can be approximately equal to the time required to install the engine  61  and front and rear suspension systems  62 ,  63  in one of the ordinary vehicle bodies  26 . 
         [0076]    Thus, two unitized compact vehicle bodies  11  can be conveyed in the same interval P 1  as an ordinary vehicle body  26 , and the time required to install the engines  13 , front and rear suspension systems  65 ,  66 , and the like in two of the unitized compact vehicle bodies  11  can be approximately equal to the time required to install the engine  61 , front and rear suspension systems  62 ,  63 , and the like in one of the ordinary vehicle bodies  26 . 
         [0077]    Consequently, when two unitized compact vehicle bodies  11  are incorporated among ordinary vehicle bodies  26 , and engines and suspension systems are installed in the two unitized compact vehicle bodies  11 , the assembly time can be approximately equal to the assembly time of an ordinary vehicle body  26 . 
         [0078]    The engines  13 , front and rear suspension systems  65 ,  66 , and other components can thereby be efficiently installed in the compact vehicle bodies  11 . 
         [0079]      FIG. 8  shows the steps of installing exterior and interior components in ordinary vehicle bodies and compact vehicle bodies. 
         [0080]    The ordinary vehicle bodies  26  and compact vehicle bodies  11  are conveyed through the exterior and interior installation area  33  on a belt conveyor (conveying line)  67  in the second conveying mechanism  36 . 
         [0081]    Two of the compact vehicle bodies  11  are conveyed as a unit in the exterior and interior installation area  33  as well, similar to the painting area  31  ( FIG. 6 ) and the drive system installation area  32  ( FIG. 7 ). 
         [0082]    Consequently, the two unitized compact vehicle bodies  11  can be moved by the belt conveyor  67  in the direction of the arrow at the same intervals P 1  as the ordinary vehicle bodies  26 . 
         [0083]    In the exterior and interior installation area  33 , right and left front side doors  68 ,  69 , right and left rear side doors  71 ,  72 , driver seats  73 , passenger seats  74 , rear seats  75 , and other components are installed in the ordinary vehicle bodies  26 . 
         [0084]    Similarly, right and left side doors  14 ,  15 , driver seats  17 , passenger seats  18 , and other components are installed in the compact vehicle bodies  11 . 
         [0085]    Thus, two doors, namely the right and left side doors  14 ,  15 , are installed in each of the compact vehicle bodies  11 . Four doors, namely the right and left front side doors  68 ,  69  and the right and left rear side doors  71 ,  72 , are installed in each of the ordinary vehicle bodies  26 . Consequently, the time required to install side doors in two of the unitized compact vehicle bodies  11  is approximately equal to the time required to install side doors in one of the ordinary vehicle bodies  26 . 
         [0086]    Furthermore, two seats, namely the driver seat  17  and the passenger seat  18 , are installed in each of the compact vehicle bodies  11 . Four seats, namely the driver seat  73 , the passenger seat  74 , and the rear seats  75 , are installed in each of the ordinary vehicle bodies  26 . Consequently, the time required to install seats in two of the unitized compact vehicle bodies  11  is approximately equal to the time required to install seats in each of the ordinary vehicle bodies  26 . 
         [0087]    Thus, two of the unitized compact vehicle bodies  11  can be conveyed in the same interval P 1  as one of the ordinary vehicle bodies  26 , and the time required to install two side doors  14 ,  15 , two seats  17 ,  18 , and the like in the two unitized compact vehicle bodies  11  is approximately equal to the time required to install four side doors  68 ,  69 ,  71   72 , four seats  73 ,  74 ,  75 , and the like in the ordinary vehicle body  26 . 
         [0088]    Consequently, when two unitized compact vehicle bodies  11  are incorporated among ordinary vehicle bodies  26 , and exterior and interior components are installed in two unitized compact vehicle bodies  11 , these components can be assembled in approximately the same time as the assembly time for an ordinary vehicle body  26 . 
         [0089]    The right and left side doors  14 ,  15 , driver seats  17 , passenger seats  18 , and other components are thereby efficiently installed in compact vehicle bodies  11 . 
         [0090]    Furthermore, unitizing two compact vehicle bodies  11  makes it possible, for example, to install interior components such as roof panels, linings, and carpets in passenger compartments in pairs. 
         [0091]    The installation costs of roof panels, linings, carpets, and other components of passenger compartments can thereby be reduced. 
         [0092]    As described above, in the vehicle production line  30  of the first embodiment, two unitized compact vehicle bodies  11  can be painted in approximately the same amount of time as an ordinary vehicle body  26 , and the components of the two unitized compact vehicle bodies  11  can be installed in approximately the same amount of time as the components of the ordinary vehicle body  26 . 
         [0093]    Consequently, two of the unitized compact automobiles  10  can be produced in approximately the same amount of time as one of the ordinary automobiles  25 . 
         [0094]    Thereby, when the vehicle bodies  11 ,  26  of the compact automobiles  10  and the ordinary automobile  25  are produced together, the compact automobiles  10  can be produced more efficiently. 
         [0095]    Next, a vehicle assembly apparatus  80  of a second embodiment will be described with reference to  FIG. 9 . In the vehicle assembly apparatus  80  of the second embodiment, components identical or similar to those in the vehicle assembly apparatus of the first embodiment are denoted by the same numerical symbols, and descriptions thereof are omitted. 
         [0096]      FIG. 9  shows an example of a drive system assembly area in the vehicle assembly apparatus of the second embodiment. 
         [0097]    The total length L 4  of a compact automobile  81  is sometimes less than the total length L 2  of the ordinary automobile  25  shown in  FIG. 3 , and greater than half the total length L 2 . 
         [0098]    In this case, when the vehicle bodies (hereinafter referred to as “compact vehicle bodies”)  82  of compact automobiles  81  are mounted in units of two on the conveying hanger  43 , the total length of each two of the unitized compact vehicle bodies  82  is greater than the total length L 2  of each of the ordinary vehicle bodies  26 . Therefore, it is difficult to mount and unitize the compact vehicle bodies  82  in pairs on the conveying hanger  43 . 
         [0099]    In view of this, in the vehicle assembly apparatus  80  of the second embodiment, for example, the drive system assembly area  84  comprises a sub-line  86 , and dollies  42  and conveying hangers  43  can be provided to the guide rail  41  after the sub-line  86 . 
         [0100]    In other words, when the compact vehicle bodies  82  are assembled together with the ordinary vehicle bodies  26 , the dollies  42  for mounting compact vehicle bodies  82  held in the sub-line  86  are added to the guide rail  41  during intervals. 
         [0101]    The intervals P 2  between the dollies  42  for mounting the compact vehicle bodies  82  are thereby smaller than the intervals P 1  between the dollies  42  for mounting the ordinary vehicle bodies  26 . 
         [0102]    Each of the compact automobiles  81  has fewer components than each of the ordinary automobiles  25 . Therefore, the intervals P 2  between the dollies  42  for mounting the compact vehicle bodies  82  are reduced to make the number of steps for assembling the multiple compact automobiles  81  match the number of steps for assembling each of the ordinary automobiles  25 . As an example, the number of steps for assembling five of the compact automobiles  81  matches the number of steps for assembling three of the ordinary automobiles  25 . Therefore, the time required to assemble five of the compact automobiles  81  is approximately the same as the time required to assemble three of the ordinary automobiles  25 , multiple automobiles of different models can be assembled with one assembly line, and the vehicles are produced more efficiently at low cost. 
         [0103]    In the vehicle assembly apparatus  80  of the second embodiment shown in  FIG. 9 , an example of a drive system assembly area  84  was described, but this description also applies to a painting area and an exterior and interior assembly area. 
         [0104]    In the exterior and interior assembly area, the compact vehicle bodies  82  and ordinary vehicle bodies  26  can be conveyed by a conveyer instead of dollies  42  and conveyor hangers  43  on a guide rail  41 . Consequently, in the exterior and interior assembly area, the interval between the compact vehicle bodies  82  conveyed by the belt conveyor is P 2 , and the interval between the ordinary vehicle bodies  26  is P 1 . 
         [0105]    As described above, in the vehicle assembly line  80  of the second embodiment, the number of steps for assembling multiple compact automobiles  81  can be matched with the number of steps for assembling ordinary automobiles  25  by reducing the intervals P 2  between dollies  42  for mounting compact vehicle bodies  82 . Thereby, when the compact automobiles  81  and ordinary automobiles  25  are produced together, the compact automobiles  81  can be produced more efficiently. 
         [0106]    The shapes of the dollies  42  and conveying hangers  43  depicted in the previous embodiments are not limited to the examples depicted, and the designs thereof can be appropriately varied. 
         [0107]    Obviously, various minor changes and modifications of the present invention are possible in light of the above teaching. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.