Abstract:
A shovel loader ( 1 ) has a vehicle body frame ( 9 ), a travel device ( 5 ), a loader device ( 20 ), and a drive power generation section for generating drive power for making the travel device ( 5 ) travel. The vehicle body frame ( 9 ) has a pair of side frames ( 9   a   , 9   a ) arranged on both the left and right sides of the shovel loader ( 1 ). The loader device ( 20 ) is made up of a pair of lift arms ( 21,21 ) vertically swingably attached to the pair of side frames ( 9   a   , 9   a ) and of a bucket ( 29 ) vertically swingably attached to the forward end of the pair of lift arms ( 21,21 ). The drive power generation section has a pair of electric motors ( 71,71 ) for individually transmitting drive power to the pair of travel devices ( 5,5 ) and capable of being controlled independent of each other so that a vehicle ( 10 ) can be made to travel in a mariner the left and right are independent of each other, and also has a battery ( 50 ) for supplying electric power to the electric motors ( 71,71 ).

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to an industrial vehicle that includes a vehicle body frame fitted to a travel member having wheels, a work device provided on the vehicle body frame, and a drive power generation section provided within the vehicle body frame. 
       TECHNICAL BACKGROUND 
       [0002]    An example of an industrial vehicle as described above is an industrial vehicle such as a shovel loader that is used for excavating the ground and moving the excavated soil, and so on (Japanese Patent Application Laid-open No. 2005-133492), that is provided with a vehicle body frame on a travel device, and fitted with a work device such as a bucket or arm or the like on the front end of the frame. Also, an engine room housing an engine, a radiator, an oil cooler, a hydraulic pump, a hydraulic valve, a hydraulic oil tank for storing hydraulic oil for hydraulic equipment, a fuel tank, and so on, are provided along with the engine inside the vehicle body frame. Also a counterweight is provided within the vehicle body frame to balance the weight of the work device fitted to the front of the vehicle body frame. 
       PROBLEMS TO BE SOLVED BY THE INVENTION 
       [0003]    Conventionally the power source of this type of industrial vehicle was an engine, and this engine caused the vehicle to travel, and the engine drove the hydraulic pump that supplied oil pressure for driving the power shovel device, the revolving motor, and so on. However, an industrial vehicle powered by an engine generates exhaust gas and noise, so in recent years it has become desirable to use a power source other than an engine, from consideration of the effect on the surrounding environment. As an alternative to an engine as a power source, the method of using electric power to cause the vehicle to travel or to drive the hydraulic pump to operate the work device can be considered, because there is no exhaust gas and the noise is low. In this method, electric power is supplied to a device such as an electric motor to drive the hydraulic pump, so it is necessary to provide a battery on the industrial vehicle, but providing a battery on the vehicle has the following problem point. When equipment such as hydraulic pumps and electric motors are operated, the equipment generates heat, so the temperature around the battery, which is installed within the vehicle body frame together with the hydraulic pump and other equipment, increases. When the temperature around the battery increases the life of the battery is shortened, and it is necessary to minimize this effect, so the battery must be disposed so that the battery is not affected by the heat generated by the equipment. However, the space within the vehicle body frame for installation of equipment such as the hydraulic pump, the electric motor, and the battery is limited, so when the space for installation of these items of equipment is taken into consideration, it is necessary to take measures against the heat generation. 
         [0004]    With the foregoing problem in view, it is an object of the present invention to provide an industrial vehicle having a battery as a power source instead of an engine, that is capable of minimizing the adverse effect on the surrounding environment, and that is not affected by the heat generation of equipment such as the hydraulic pump and the electric motor, disposed within the vehicle body frame. 
       MEANS TO SOLVE THE PROBLEMS 
       [0005]    To solve the above problem, the industrial vehicle according to the present invention includes a vehicle body frame; a travel member (for example the travel device  5  in the embodiments) installed on the vehicle body frame; a work device (for example the loader device  20  in the embodiments) installed on the vehicle body frame; and a drive power generation section (for example the electric motor  71  in the embodiments) that is provided in the vehicle body frame and that generates drive power to cause the travel member to travel, wherein the vehicle body frame has a pair of side frames provided on the left and right sides of the industrial vehicle, the work device comprises a pair of lift arms (for example the arms  21  in the embodiments) vertically swingably installed on the pair of side frames at their base ends, and a bucket vertically swingably installed on the front ends of the pair of lift arms, and the drive power generation section comprises an electric motor that causes the travel member to travel by transmitting drive power to the travel member, and a battery or a large capacity condenser or a combination of a battery and a large capacity condenser that supplies electric power to the electric motor. 
         [0006]    Also, in the industrial vehicle constituted as above, preferably the travel member comprises a pair of travel members provided on the left and right of the vehicle body frame, the electric motor is provided in the drive power generation section as a pair of left and right electric motors, and by independently controlling the drive of the pair of electric motors, the drive power can be individually transmitted to the pair of travel members and the pair of travel members can travel independently. 
         [0007]    Also, in the industrial vehicle constituted as above, preferably the battery is housed in a battery storage part formed in a planar shape below a floor surface of the vehicle body frame. 
         [0008]    Further, in the industrial vehicle constituted as above, preferably a battery housing aperture that opens to the battery storage part is formed in the rear surface of the vehicle body frame, and the battery is inserted and removed through the battery storage aperture. 
         [0009]    Also, in the industrial vehicle constituted as above, preferably the battery is a lithium ion battery or an organic radical battery. 
       ADVANTAGEOUS EFFECTS OF THE INVENTION 
       [0010]    According to the industrial vehicle of the present invention, the vehicle is made to travel by a drive power source other than an engine, and by transmitting the rotational drive power from an electric motor that is supplied with electric power from a battery to the wheels provided on a travel device, the travel member, in other words the industrial vehicle, is made to travel. In this way, the industrial vehicle according to the present invention does not use an engine as the power source, so no exhaust gas is emitted as the industrial vehicle travels, and the noise generated is low compared with a vehicle with an engine as drive power source, so it is possible to minimize the adverse impact on the surrounding environment. 
         [0011]    Further, the travel member includes a pair of travel members provided on the left and right of the vehicle body frame, the electric motor is provided in the drive power generation section as a pair of left and right electric motors, and by independently controlling the drive of the pair of electric motors, the drive power can be individually transmitted to the pair of travel members and the pair of travel members can travel independently, so the industrial vehicle with the electric motor as the source of drive power can be turned right or turned left, and in addition the industrial vehicle can revolve on the spot. 
         [0012]    Also, the battery is housed in a battery storage part formed in a planar shape below a floor surface of the vehicle body frame. Then equipment that generates heat such as the hydraulic pump and the electric motor is disposed within the vehicle body frame in a position above the battery, so the heat generated by the hydraulic pump and so on, due to the operation of the hydraulic pump and so on, can be dissipated upwards within the vehicle body frame, so it is possible to minimize the effect of the heat on the battery. Here, an oil cooler with a cooling fan may be disposed within the vehicle body frame, so that if the heat from the hydraulic pump and the electric motor are dissipated to the outside of the vehicle by the oil cooler, it is possible to further reduce the effect of heat on the battery. Also, by disposing the storage position of the battery below the hydraulic pump, and so on, the freedom of arrangement of the hydraulic pump and other equipment other than the battery can be increased. Also, by inserting and removing the battery that is stored in the battery storage part of this type via a battery storage aperture that opens to the battery storage part in the rear surface of the vehicle body frame, it is possible to simplify the operation of changing the battery. 
         [0013]    Further, by using a lithium ion battery or an organic radical battery as the battery, or using a large capacity condenser instead of the battery, or using a composite secondary battery system that includes a battery and a large capacity condenser in combination, it is possible to provide the same voltage with a smaller volume compared with a lead battery that is conventionally used as the battery of an industrial vehicle, so it is possible to reduce the space occupied by the battery within the vehicle body frame, and it is possible to increase the space provided for the hydraulic pump and the electric motor, and so on, by that amount. Also, these batteries are lighter than lead batteries, and this has the advantage that the operation of changing the battery is simplified. Either a lithium ion battery or an organic radical battery may be used as a high capacity rechargeable battery, but in particular if an organic radical battery is used, the battery can be made lighter, and can be recharged in a shorter period of time. Also, by using a composite constitution having a battery and a large capacity condenser, it is possible to reduce the voltage drop due to a sudden overload. This is effective means in the case when battery capacity of the lithium ion battery or the organic radical battery is reduced. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  shows a shovel loader as an example of an industrial vehicle according to the present invention,  FIG. 1A  is a plan view of the shovel loader, 
           [0015]      FIG. 1B  is a left side view of the shovel loader; 
           [0016]      FIG. 2  is a rear view of the above shovel loader; 
           [0017]      FIG. 3  is a front view of the above shovel loader; 
           [0018]      FIG. 4  is a block diagram showing the constitution of the hydraulic and other equipment provided in the above shovel loader; 
           [0019]      FIG. 5A  is a left side view showing a part of the shovel loader to show an example of the arrangement of the electric motor and so on in the shovel loader,  FIG. 5B  is a diagram schematically showing the electric motor and so on arranged in a line in the left-right direction of the shovel loader; and 
           [0020]      FIG. 6  is an isometric diagram showing the area around the battery storage part that houses the battery provided in the above shovel loader. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0021]    The following is an explanation of the preferred embodiments of the present invention based on  FIGS. 1 through 6 . In the present embodiment, an embodiment of a shovel loader that is used for excavating the ground and moving the excavated soil, and so on, is described. First the shovel loader according to the present invention is explained. As shown in  FIGS. 1 through 3 , the shovel loader  1  includes a travel device  5  having crawler tracks  3 , a vehicle body frame  9  having a pair of travel devices  5  installed on the left and right thereof, a loader device  20  installed on the vehicle body frame  9 , and an operator&#39;s cabin  30  provided in approximately the center part in the front to rear direction of the vehicle body frame  9 . Hereafter the travel devices  5  together with the vehicle body frame  9  is referred to as the “vehicle  10 ”. 
         [0022]    A pair of side frames  9   a  is formed projecting upwards on the left and right sides of the vehicle body frame  9 . Also, besides the side frames  9   a , the vehicle body frame  9  includes an upper frame  9   b  extending in the left-right direction between the pair of side frames  9   a  in the upper part of the rear end part of the vehicle  10 , a rear frame  9   c  forming the rear end part of the vehicle  10 , and a flat plate-shaped floor surface  9   d  formed below the operator&#39;s cabin  30  that can be used by an operator in the operator&#39;s cabin  30 . 
         [0023]    The loader device  20  is fitted to the side frames  9   a . The loader device  20  includes a pair of arms  21  vertically swingably attached to the inside of the top portion of the pair of side frames  9   a , a bucket  29  vertically swingably attached to the front ends of the pair of arms  21 , and a raising and lowering cylinder  23  for raising and lowering each of the arms  21 . The arm  21  includes a straight portion  21   a  that extends from the top portion of the side frame  9   a  towards the front of the vehicle, and a curved portion  21   b  that gradually curves downwards progressively from the end portion of the straight portion  21   a , and the straight portion  21   a  and the curved portion  21   b  are integral. A step portion  21   c  is formed extending downwards between the front end of the straight portion  21   a  and the base end of the curved portion  21   b . An end portion of the rod part of the raising and lowering cylinder  23  is swingably connected to the straight portion  21   a , and the cylinder tube end portion of the raising and lowering cylinder  23  is swingably connected to the side frame  9   a . Therefore when the raising and lowering cylinder  23  extends and contracts, the arm  21  is raised and lowered. The arms  21  are in the storage state when the arms  21  are lowered to the front of the vehicle extending in the front-rear direction, and with the bucket  29  tilted towards the front of the vehicle and in contact with the ground. A strengthening member  25  is fitted between the curved portions  21   b  of the pair of arms  21  extending in the left-right direction. The reinforcing member  25  is located to the front of the vehicle  10  when the arms  21  are in the storage state. 
         [0024]    The base end of a bucket cylinder  24  is swingably attached to the base end of the curved portion  21   b  of the arms  21 , and the front end of the bucket cylinder  24  is swingably attached to the base of the bucket  29 . Therefore, when the bucket cylinder  24  is extended and contracted, the bucket  29  pivots vertically. In this case, when the bucket cylinder  24  is contracted, the bucket  29  pivots upwards and excavation work is performed, and when the bucket cylinder  24  is extended, the bucket  29  pivots downwards and soil discharge work is performed. 
         [0025]    Next, the operator&#39;s cabin  30  provided in the shovel loader  1  is explained. The pair of arms  21  is disposed to the outside of the operator&#39;s cabin  30 , which is disposed in approximately the center of the vehicle  10  in the front-rear direction, in the left-right direction. The operator&#39;s cabin  30  is box-shaped, and includes an open aperture portion  31  towards the vehicle front, a pair of side plate portions  33  extending in the front-rear direction and separated by a predetermined distance in the left-right direction, and a top plate portion  35  extending across the tops of the pair of side plate portions  33 , and extending to the top portion of the rear end of the pair of side plate portions  33  to cover the top and the rear of the operator&#39;s cabin  30 . A plurality of approximately rectangular shaped holes  39  is formed in the pair of side plate portions  33 , so that the interior of the operator&#39;s cabin  30  and the exterior of the vehicle are linked via the holes  39 . 
         [0026]    An operator&#39;s seat  12  is disposed within the operator&#39;s cabin  30  so that an operator can sit facing towards the front of the vehicle. Also, an operating device  14  is disposed to the left and right of the operator&#39;s seat  12  for operating the loading device  20  (see  FIG. 3 ). The operating device  14  includes a left operating lever  14   a  and a right operating lever  14   b , when the left operating lever  14   a  is tilted the travel device  5  operates, and when the right operating lever  14   b  is tilted the arms  21  of the loader device  20  are raised or lowered and the bucket  29  carries out excavation work or soil discharge work. The operator&#39;s cabin  30  is vertically swingably attached so that it can pivot about the rear portion of the vehicle body frame  9 . Therefore, if the front of the operator&#39;s cabin  30  is pulled upwards, the operator&#39;s cabin  30  can pivot upwards about the pivot connection position as center. When the operator&#39;s cabin  30  is pivoted upwards, a hydraulic pump  72  that is housed within the vehicle body frame  9  and is the source of power for the travel device  5  and the loader device  20 , and so on, can be exposed from the top. 
         [0027]    As shown in  FIG. 4 , a controller  100  provided within the vehicle body frame  9  and that controls the overall operation of the travel device  5  and the loader device  20  receives operation signals output from the operating device  14  when the operating device  14  is operated, the controller  100  outputs control signals to a hydraulic control valve  80 , and the hydraulic control valve  80  controls the supply and discharge of hydraulic oil to the arm cylinders  23  and so on, based on the control signals from the controller  100 . When control signals are output from the controller  100 , the hydraulic control valve  80  controls the supply and discharge of hydraulic oil output from the hydraulic pump  72  that is driven by a motor that is supplied with electric power, and the arms  21  are raised or lowered, and the bucket  29  is operated. 
         [0028]    The hydraulic control valve  80  includes an arm control valve  83  corresponding to the arm cylinder  23  that raises and lowers the arms  21 , and a bucket control cylinder  84  corresponding to the bucket cylinder  24  that operates the bucket  29 . Also, control of the supply and discharge of hydraulic oil flowing to the arm cylinder  23  and so on is carried out by controlling the amount of opening of the arm control valve  83  and the bucket control valve  84  in the hydraulic control valve  80 . Also, control signals output from the controller  100  corresponding to the operation of the operating device  14  are output to a motor variable speed control device  115 , when control signals are output from the controller  100  to the motor variable speed control device  115 , the rotation speed of an electric motor  71  is varied, and the electric motor  71  is controlled to output the appropriate torque, so that the travel speed of the travel device  5  can be freely varied. 
         [0029]    Here, an example of the arrangement of various types of equipment within the vehicle body frame  9  is explained. Below the operator&#39;s seat  12  and within the space covered by the pair of side frames  9   a , the upper frame  9   b , and the rear frame  9   c , equipment such as the electric motor  71  and the hydraulic pump  72 , which are the power source for operating the travel device  5  and the loader device  20 , are disposed. Among this equipment, the pair of left and right electric motors  71 ,  71  that are supplied with electric power from a battery  50  are arranged sideways in the left-right direction (arranged so that the long direction of the motor shaft coincides left-right direction of the vehicle  10 ) in both the left and right sides of the rear portion within the vehicle body frame  9  (see  FIG. 2 ). The electric motors  71  are both induction motors, supplied with an alternating current voltage by inverters provided in the controller  100 . When an alternating current flows in the windings of the stator of the electric motors  71   a  rotating magnetic field is generated, and the rotor is rotated by the interaction with the induction current generated in the rotor, so it is possible to vary the rate of rotation using the motor variable speed control device  115 . 
         [0030]    The electric motor  71  is not limited to the case that it is constituted by an induction motor, but the electric motor  71  may also be constituted by an interior permanent magnetic (IPM) motor, or a servo motor. An IPM motor is a type of reluctance motor with rare earth permanent magnets embedded within the interior of the stator (iron), and high efficiency (output is high relative to the electric power supplied) can be achieved by using the torque generated by the attraction and repulsion force between the permanent magnets and the stator, and the attraction and repulsion force between the rotor and stator. When the electric motor  71  is constituted by a servo motor, it is possible to measure the angle of the rotation shaft of the electric motor  71  by including measurement means such as a resolver or encoder, and by varying the voltage applied to the electric motor  71 , it is possible to finely control the rotation speed of the rotation shaft of the electric motor  71 . 
         [0031]    As described above, by providing a pair of left and right electric motors  71  within the vehicle body frame  9 , and by supplying each motor  71 ,  71  individually with electric power from the battery  50  under the control of the controller  100 , it is possible to independently control the rotation of the left and right electric motors  71 ,  71 . By independently controlling the rotation of the left and right electric motors  71 ,  71  in this way, it is possible to drive only one of the travel devices  5  fitted to the left and right of the vehicle body frame  9 , for example the travel device  5  on the left side, so that the vehicle  10  can be made to revolve. Preferably reduction gears are provided connected to the output shaft of the electric motor  71 , and the travel device  5  is driven via the reduction gears. As a result of this, the size of the electric motor  71  can be reduced. 
         [0032]    The hydraulic pump  72 , which supplies pressurized hydraulic oil for driving the arm cylinder  23 , the bucket cylinder  24 , and other hydraulic equipment, and which is driven by the electric motors  71 ,  71 , is installed to the front of the electric motors  71 ,  71 . A hydraulic oil tank  73  that stores hydraulic oil for operating the hydraulic equipment is disposed to the rear of the electric motor  71  in the rear end portion within the vehicle body frame  9  close to the rear frame  9   c.    
         [0033]    A battery storage part  17  is formed in a flat shape below the floor surface  9   d  of the vehicle body frame  9 , and the battery  50  is housed in the battery storage part  17 . The equipment that generates heat, such as the electric motor  71  and the hydraulic pump  72  are disposed in positions above the battery  50  within the vehicle body frame  9 , so heat generated by the hydraulic pump  72  by operation of the hydraulic pump  72  is dissipated upwards within the vehicle body frame  9 , so it is possible to minimize the effect of the heat on the battery  50 . By providing an oil cooler with a cooling fan within the vehicle body frame  9 , so that the heat from the hydraulic pump and the electric motor is released outside the vehicle  10 , it is possible to further reduce the effect of the heat on the battery  50 . Also, by placing the storage position of the battery  50  below that of the hydraulic pump  72  and other equipment, it is possible to increase the freedom of arrangement of the hydraulic pump  72  and other equipment apart from the battery  50 . 
         [0034]    The battery  50  is a high capacity rechargeable lithium ion battery or an organic radical battery, that can be removed from or inserted into the vehicle  10  in the front-rear direction (in the direction of the arrow A) using a slide mechanism  60  that is described later. Also, the battery  50  is disposed flat in a position below the floor surface  9   d  of the vehicle body frame  9 , so it is possible to lower the position of the center of gravity of the vehicle  10 , and improve the stability. Also, the battery  50  is disposed in a planar shape, so the heat dissipation area is greater than if arranged in a rectangular parallelepiped shape, so it is possible to effectively dissipate the heat generated by the battery  50  itself. 
         [0035]    Also, in particular, in the organic radical battery referred to above, organic radical material, which is a type of thermoplastic resin, is used as the positive electrode material. The characteristics of organic radical batteries include a higher capacity than lithium ion batteries, and the electrochemical reaction speed is higher, so the recharging time is shorter. Also, unlike lithium ion batteries, organic radical batteries do not use heavy metal oxides such as lithium cobalt oxide or lithium manganese oxide as the electrodes, so they are lighter and the impact on the environment is lower. 
         [0036]    Further, instead of the battery  50  as the electric power source for the electric motor  71 , a large capacity condenser, which is not shown on the drawings, may be used. Also, a secondary battery system may be used having a composite constitution with a combination of the battery  50  and a large capacity condenser, which is not shown in the drawings, by connecting the battery  50  and the large capacity condenser in parallel. By using the composite constitution of the battery  50  and the large capacity condenser, as described above, it is possible to minimize the reduction in voltage due to a sudden overload. This an effective means when the battery capacity of the lithium ion battery or the organic radical battery is reduced. 
         [0037]    The arrangement of the battery  50  within the vehicle body frame  9  is not limited to the planar arrangement as described above, and the batteries  50  may be formed stacked so that the overall shape is rectangular parallelepiped. In this case, the weight balance of the vehicle  10  and the dissipation of heat from the equipment must be considered, the rectangular parallelepiped battery  50  is preferably disposed for example near the rear frame  9   c , in other words disposed in the position where the hydraulic tank  73  is disposed in  FIG. 1B , and the other equipment such as the electric motor  71  and the hydraulic pump  72  is preferably disposed facing sideways aligned in the left-right direction of the vehicle  10  in a position above the battery  50 . 
         [0038]    The controller  100  that controls the overall operation of the loader device  20  is provided to the front of the hydraulic pump  72  above the battery  50 . As stated above, the controller  100  receives operation signals based on the operation of the operating device  14 , and outputs control signals to the hydraulic control valve  80 . The hydraulic control valve  80  controls the supply and discharge of hydraulic oil to the arm cylinder  23  and the like based on the control signals from the controller  100 , so it is possible to raise and lower the arms  21 . By swiveling the operator&#39;s cabin  30 , it is possible to expose the controller  100  and carry out changing operations. 
         [0039]    The controller  100  includes an amplifier and other electronic equipment, so the controller  100  is particularly weak against vibrations, therefore in order to prevent faulty operation of the controller  100  caused by vibrations due to operation of the travel device  5  or the loader device  20 , an elastic member  101  that absorbs vibrations, such as for example vibration prevention rubber (of course a member such as a spring may also be used) is installed. 
         [0040]    The power source of the travel device  5  is the electric motor  71  as described above, and the travel device  5  is driven by transmission of the drive power of the electric motor  71 , which causes the vehicle  10  to travel. A sprocket  5   a  on which the crawler tracks  3  are wound and which is positioned on the same axis as the rotation shaft of the electric motor  71  rotates together with the electric motor  71  and drives the crawler tracks  3 . The travel device  5  includes a plurality of driven wheels, a driven wheel  5   b , a driven wheel  5   c , a driven wheel  5   d , a driven wheel  5   e , and a driven wheel  5   f  in that order from the front towards the rear of the vehicle  10 , and the crawler tracks  3  are wound around the driven wheels  5   b  through  5   f  together with the sprocket  5   a . When the crawler tracks  3  are driven by the rotation of the sprocket  5   a , the driven wheels  5   b  through  5   f  rotate, so it is possible to cause the vehicle  10  to travel forward or backward corresponding to the direction of rotation of the electric motor  71  (forward or reverse) (in accordance with the direction of rotation of the sprocket  5   a ) based on the manipulation of tilting the left operating lever  14   a.    
         [0041]    As stated above, the pair of electric motors  71 ,  71  is provided in the left and right of the vehicle  10 , and it is possible to control and drive the left and right independently, so the drive power of the electric motors  71 ,  71  is transmitted individually to the pair of travel devices  5 ,  5 , and it is possible for the travel devices  5 ,  5  to travel independently. In this way, it is possible to vary the drive speed to the travel device  5  on the left and right, and it is possible to drive only one of the pair of travel devices  5  on the left or right. Here, if the drive speed of the travel device  5  is different on the left and right, the vehicle  10  can turn to the left or turn to the right, also, if only one of the travel devices  5  on the left or right is driven, the vehicle  10  can rotate on the spot in a plane either clockwise or counterclockwise. 
         [0042]    Further, in the present embodiment, the travel device  5  is a crawler that includes the crawler tracks  3  wound around the sprocket  5   a  and the driven wheels  5   b  through  5   f , but the travel device is not necessarily limited to this, and a constitution in which the electric motor  71  is provided as the power source and a plurality of rotational drive wheels to which the drive power of the electric motor  71  is transmitted is provided on the left and right of the vehicle  10  may be used. Also, when a plurality of wheels is used as the drive device, by controlling and driving the pair of electric motors  71 ,  71  independently, turning left and right and revolving clockwise and counterclockwise on the spot may be carried out, as described above. 
         [0043]    As shown in  FIGS. 5A and 5B , an electric motor  171  for driving the loader device  20 , in other words for driving the hydraulic pump  72 , may be disposed in the rear part of the vehicle  10  (to the front of the rear frame  9   c ) separately from the electric motor  71  for driving the travel device  5 . With this type of arrangement, as shown in  FIG. 5B , the hydraulic control valve  80 , which controls the supply and discharge of hydraulic oil to the arm cylinder  23  and so on based on control signals from the controller  100  which includes a revolving drive control valve and the like, is provided in the left hand side of the vehicle  10  adjacent to the electric motor  171 . Also, a hydraulic oil tank  173  that stores hydraulic oil for operating the loader device  20  is provided in the right hand side of the vehicle  10  adjacent to the electric motor  171 . In other words, in the rear portion of the vehicle  10 , the hydraulic control valve  80 , the electric motor  171 , and the hydraulic oil tank  173  are arranged in a line from the left side to the right side of the vehicle  10  in that order. 
         [0044]    Here, referring to  FIG. 6 , the area around a battery storage aperture  44  for taking the battery  50  out of the vehicle body frame  9  is explained. In the rear end of the vehicle  10 , the battery storage aperture  44  as shown in  FIG. 6  is formed, the battery storage aperture  44  can be opened by swiveling a storage lid  48  that is capable of being swiveled vertically by hinges  49 ,  49  disposed to the left and right of the bottom end of the aperture of the battery storage aperture  44 , in the downward direction (the storage lid  48  may also swivel vertically about hinges  49  provided in the top end of the aperture of the battery storage aperture  44 ). Also, by withdrawing or inserting the battery  50  in the front-rear direction via the battery storage aperture  44  with the battery storage aperture  44  in the open state, it is possible to remove or insert the battery  50  with respect to the battery storage part  17 , which is covered by a lower cover  43 . 
         [0045]    As shown in  FIG. 6 , a pair of grips  46 ,  46  that an operator can grip with their hands is formed on the left and right of the front surface of a box-shaped drawer  45  that is open to the top that is a battery case for storing the battery  50 . A plurality of cylindrical-shaped batteries  50 ,  50 , . . . is disposed upright within the drawer  45  and aligned left-right and front-rear filling the interior of the drawer  45 . Also, hook-shaped lock levers  47 ,  47  that are capable of being latched to level latching portions, which are not shown in the drawings, provided in the battery storage part  17  are installed on the left and right of the rear end surface of the drawer  45 , each extending in the front-rear direction. The lock levers  47  are linked to lock release portions, which are not shown in the drawings, provided in the grips  46 , so that the lock levers  47  can be latched and released by operation of the lock release portions. 
         [0046]    The battery  50  is a lithium ion battery or an organic radical battery, as described above, having the same voltage but a smaller volume compared with lead batteries that are conventionally used as the battery of industrial vehicles, so it is possible to make the space occupied by the battery smaller, so it is possible to provide a larger space for arrangement of the hydraulic pump and the electric motor, and so on, by this amount. Further, lithium ion batteries and organic radical batteries are lighter than lead batteries, so they have the advantages that it is possible to simplify the work of changing the batteries, and the charging time is shorter. 
         [0047]    The slide mechanism  60  for moving the box-shaped drawer  45  that houses the battery  50  in the front-rear direction is constituted as follows. The slide mechanism  60  is provided on both sides of the drawer  45  (in  FIG. 6 , only the slide mechanism  60  provided on the left side of the drawer  45  is shown), and includes a beam-shaped rail  61  that extends front to rear substantially horizontally; a pair of front-rear rollers  62   a ,  62   b , the axis of the center of rotation thereof is installed in the direction of the left-right axis of the interior of the vehicle body frame  9 , that rotate in the front to rear direction while contacting the bottom surface of the rail  61 ; a pair of front-rear rollers  65 ,  65 , the axis of the center of rotation thereof is installed in the direction of the left-right axis of the interior of the vehicle body frame  9 , that rotate in the front to rear direction while contacting the top surface of the rail  61 ; a column-shaped front stopper  63  provided extending vertically at the front end of the rail  61 ; and a column-shaped rear stopper  64  provided extending vertically at the rear end of the rail  61 . The slide mechanism  60  provided on the right side of the drawer  45  is also constituted with a rail  61  and so on, as described above. 
         [0048]    Here the maintenance of the battery  50  stored in the battery storage part  17  constituted as described above is explained. Battery maintenance as discussed here means changing the battery  50 . The maintenance of the battery  50  is carried out with the storage lid  48  opened and swiveled downwards, by the operator placing the hands in the grips  46  provided in the drawer  45 , carrying out the release operation of the lock levers  47  using the lock release portions, and pulling the drawer  45  forward until the front surface of the rear stopper  64  contacts the roller  62   b . At this time, the battery  50  is exposed from the battery storage part  17 , so the operation of changing the battery  50  can be carried out. Each of the rails  61 ,  61  are sandwiched between the rollers  62   a ,  62   b  on the lower side and the rollers  65 ,  65  on the top side, so the pulled out drawer  45  will not be pulled out from the vehicle  10  by the operator pulling the grips  46 . 
         [0049]    After the operation of changing the battery  50  is finished, the drawer  45  is pushed into the battery storage part  17  until the rear surface of the front stopper  63  contacts the roller  62   a , with the hands on the grips  46 . When the front stopper  63  contacts the roller  62   a , the hook-shaped lock levers  47  latch with the lever latching portions, which are not shown in the drawings, the drawer  45  is locked so that it cannot be pulled forward. Then, the storage lid  48  is swiveled upwards and the battery storage aperture  44  is closed, which completes the series of maintenance operations, so it is possible to proceed to excavation work, or the like.