Abstract:
A power shovel vehicle including a hydraulic pump that outputs hydraulic oil for operating a hydraulic actuator, an electric motor for driving the hydraulic pump, a main battery for supplying direct current electric power, an inverter for converting the direct current electric power into alternating current electric power and operating the electric motor, a second relay for making and breaking the connection between the main battery and the inverter, an operating device for operating the hydraulic actuator, a controller for controlling operation of the hydraulic actuator and inverter, and turning on and off the second relay, a first relay for making and breaking the connection between the main battery and the controller, a power source monitoring controller for monitoring conditions of the main battery and turning on and off the first relay, a hydraulic sensor for detecting the discharge pressure of the hydraulic pump, and an electric current sensor for measuring a load current flowing into the inverter.

Description:
TECHNICAL FIELD 
     The present invention relates to a working vehicle having an electric motor driven by a battery as the drive power source. 
     TECHNICAL BACKGROUND 
     In conventional working vehicles the drive power source is normally an engine. However, in circumstances in which an engine cannot be used, such as in an underground construction site, construction machinery with an electric motor as the power source is used (see for example Japanese Patent Application Laid-open No. 2004-225355). The power source for the electric motor is a commercial power supply, or a battery on the construction machinery that is charged from a commercial power supply. 
     DISCLOSURE OF THE INVENTION 
     Problems to be Solved by the Invention 
     However, in this type of working vehicle when the electric motor is driven by a battery, there is the problem that if it is necessary to frequently charge the battery, the operation efficiency becomes poor. Therefore it is necessary to operate the working vehicle without charging the battery during a working period of at least one day. 
     With the foregoing in mind, it is an object of the present invention to provide a working vehicle constituted to prevent consumption of electric power from the charged battery when the hydraulic actuator of the like is not being operated. 
     Means to Solve the Problems 
     To resolve the above problem, the working vehicle according to the present invention (for example, the crawler type power shovel  1  according to the embodiments) is a working vehicle operated by a hydraulic actuator, the working vehicle comprising: a hydraulic pump that outputs hydraulic oil for operating the hydraulic actuator; an electric motor that drives the hydraulic pump; a main battery that supplies direct current electric power; an inverter that operates the electric motor by converting the direct current electric power from the main battery into alternating current electric power and supplying the alternating current electric power to the electric motor; an electric motor relay for making and breaking the connection between the main battery and the inverter (for example, the second relay  47  according to the embodiments); an operating device for operating the hydraulic actuator; a controller which is operated by the direct current electric power from the main battery, and which controls the operation of the hydraulic actuator and the inverter in accordance with operation signals output from the operation device, and makes and breaks the connection between the main battery and the inverter in use of the electric motor relay; a controller relay for making and breaking the connection between the main battery and the controller (for example, the first relay  46  according to the embodiments); a power source monitoring controller that monitors the state of the main battery, and that makes and breaks the connection between the main battery and the controller using the controller relay; an oil pressure sensor for measuring the output oil pressure of the hydraulic oil output from the hydraulic pump; and a current sensor for measuring the value of the load current flowing from the main battery to the inverter. For the working vehicle, configuration is employed to execute: a first step in which the controller, when determination is made that there has been no variation in the magnitude of the output oil pressure measured by the oil pressure sensor and the load current measured by the current sensor within a set period of time, breaks the connection between the main battery and the inverter and stops the motor in use of the electric motor relay; a second step in which the controller, when determination is made that the state where no operating signal has been output from the operating device has continued during a predetermined set period of time, transmits a command signal to the electrical power monitoring controller; and a third step in which the power source monitoring controller, when the transmitted signal is received, breaks the connection between the main battery and the controller in use of the controller relay, and stops the controller. 
     In the working vehicle according to the present invention, preferably the controller has a motor start up switch, and in the second step, the controller, when determination is made that the motor start up switch has been operated, connects the main battery and the inverter in use of the electric motor relay, and starts the electric motor in order to return to the first step. 
     Also, in the working vehicle according to the present invention, preferably the power source monitoring controller has a power supply switch, and in the third step, after stopping the controller, the power source monitoring controller, when determination is made that the power supply switch has been operated, connects the main battery to the controller and the inverter using the controller relay and the electric motor relay in that order 
     Advantageous Effects of the Invention 
     When the working vehicle according to the present invention is constituted as described above, the supply state of hydraulic oil to the hydraulic actuator and the manipulation state of the operating device are monitored by the controller, and when oil pressure is not necessary the electric power supply to the inverter is stopped, and further the electric power supply to the controller is stopped, so unnecessary power consumption from the main battery is minimized and it is possible to lengthen the time that the power shovel can carry out work without charging the main battery unit. Even when the power supply to the inverter and the controller is stopped in this way, by pressing the motor start up switch or the power supply switch, it is possible to simply supply electric power to the inverter and the controller. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective diagram showing the constitution of a crawler type power shovel as an example of a working vehicle according to the present invention; 
         FIG. 2  is a block diagram showing the constitution of the hydraulic unit and power supply unit in the above power shovel; 
         FIG. 3  is a flowchart showing the electric power start up process of the power supply unit; and 
         FIG. 4  is a flowchart showing the electric power saving control in the power supply unit. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following is an explanation of the preferred embodiments of the present invention with reference to the drawings. First, a crawler type power shovel  1  is explained as an example of a working vehicle according to the present invention, using  FIG. 1 . This power shovel  1  is intended to be used in comparatively enclosed spaces such as underground and the like, and operates by using electrical power from a battery (hereafter referred to as a main battery  50   a ). The power shovel  1  includes a travel bogey  4  that forms a travel device  2 , a blade  9  provided to the rear of the travel bogey  4  that is capable of swiveling vertically, a rotation platform  11  that is capable of rotating provided above the travel bogey  4 , a power shovel mechanism  13  swivelably connected to the front of the rotation platform  11 , and an operator&#39;s cabin  15  provided above the rotation platform  11 . 
     The travel device  2  includes the approximately H-shaped travel bogey  4 , and a travel mechanism  3  provided on the left and right of the travel bogey  4 . The travel mechanism  3  includes a drive sprocket wheel  5  provided to the front and an idler wheel  6  (on occasions the drive sprocket wheel  5  and the idler wheel  6  will be referred to collectively as the “crawler wheels”) provided to the rear on the left and right of the travel bogey  4 , and a pair of left and right crawler tracks  7  wound around the two wheels  5 ,  6 . Each of the drive sprocket wheels  5  is driven by left and right drive motors (hydraulic motors), which are not shown on the drawings, so that the power shovel  1  can move. Also, the rotation platform  11  can be rotated relative to the travel bogey  4  by a rotation motor (hydraulic motor), which is not shown on the drawings. 
     The power shovel mechanism  13  includes a boom  16  swivelably connected to the front of the rotation platform  11  so that the boom  16  can be freely raised and lowered, an arm  17  swivelably connected to the top of the boom  16  so that the arm  17  can be freely swiveled vertically in the plane of vertical movement of the boom  16 , and a bucket  18  connected to the top of the arm  17  so that the bucket  18  can be freely swiveled. The boom  16  is raised and lowered by a boom cylinder  21 , the arm  17  is swiveled by an arm cylinder  22 , and the bucket  18  is swiveled by a bucket cylinder  23 . The cylinders and the drive motors referred to above and the rotation motor are driven by hydraulic oil supplied from a hydraulic unit  30 , as shown in  FIG. 2 , so in the following explanation, these are collectively referred to as the “hydraulic actuator  20 ”. Also, operation of the power shovel mechanism  13  is carried out using an operating device  14  provided within the operator&#39;s cabin  15 . 
     The hydraulic unit  30  includes an electric motor  31 , a hydraulic pump  32  that is driven by the electric motor  31  and that outputs hydraulic oil at a specific oil pressure and flow rate, a tank  33  in which hydraulic oil accumulates, a control valve (electromagnetic proportional valve)  34  that controls the supply of hydraulic oil output from the hydraulic pump  32  to the hydraulic actuator  20  in a supply direction and supply flow rate in accordance with the manipulation of the operating device  14 , and an oil cooler  35  that cools the hydraulic oil whose temperature has risen. Operation signals output from the operating device  14  are input to a controller  42 , which is described later, and the controller  42  outputs command signals to the control valve  34  in accordance with the operation signals such that the control valve  34  is controlled. 
     Direct current electric power supplied from the main battery unit  50  is converted into alternating current electric power having a predetermined voltage and frequency by an inverter  43  and supplied to the electric motor  31 . A main battery unit  50  is constituted by a lithium ion battery, and includes a main battery  50   a  capable of outputting direct current high voltage (for example, direct current 336V), and a protective circuit  50   b  that obtains the status of and protects the main battery  50   a.    
     Next, a power supply system  40  that supplies electrical power to the electric motor  31  using the main battery unit  50  is explained. The power supply system  40  includes a power source monitoring controller  41  that monitors the output voltage and status of the main battery unit  50 , and a controller  42  that controls the inverter  43  and the control valve  34  to operate electric motor  31  and hydraulic actuator  20 , as well as connecting and disconnecting the electric power supplied to the inverter  43 . 
     In order to operate the power source monitoring controller  41  when starting the power shovel  1 , the power supply system  40  includes a backup battery  44  that is constituted by a lithium ion battery that outputs a direct current voltage (for example, 12.6V direct current) for operating this the power source monitoring controller  41 , and the backup battery  44  and the power source monitoring controller  41  are connected and disconnected by a key switch (main power supply switch)  45  provided within the operator&#39;s cabin  15 . The power source monitoring controller  41  supplies electric power from the backup battery  44  to the protective circuit  50   b  of the main battery unit  50 , and obtains the status of the main battery  50   a  from the protective circuit  50   b.    
     The main battery  50   a  of the main battery unit  50  is connected to and supplies electric power to the controller  42  and the inverter  43 . The main battery  50   a  and the controller  42  are connected by a first contact point  46   a  of a first relay  46 , so the connection between the main battery  50   a  and the controller  42  is made and broken by the first relay  46 . Also, the main battery  50   a  and the inverter  43  are connected by a contact point  47   a  of a second relay  47 , so the connection between the main battery  50   a  and the inverter  43  is made and broken by the second relay  47 . The controller  42  includes a DC-DC converter  48  that converts high voltage direct current voltage supplied from the main battery  50   a  into a low voltage direct current voltage (the voltage for operating the power source monitoring controller  41 ), the output of the DC-DC converter  48  is connected between the backup battery  44  and the key switch  45  via a protective diode  51 , in other words, connected to the power source monitoring controller  41  and the backup battery  44 , and these connections are made and broken by a second contact point  46   b  of the first relay  46 . 
     The first and second contact points  46   a,    46   b  of the first relay  46  are connected and disconnected by the control of the controller  41 . The first and second contact points  46   a ,  46   b  are normally maintained disconnected (OFF state), and when a voltage is applied to the first relay  46  from the power source monitoring controller  41  the first and second contact points  46   a ,  46   b  are turned ON, and when the contact points  46   a  and  46   b  are connected, the main battery  50   a  and the controller  42 , as well as DC-DC converter  48  and the power source monitoring controller  41  and a backup battery  44  are connected. When the second contact point  46   b  of the first relay  46  is connected, electric power is supplied to the DC-DC converter  48  by the power source monitoring controller  41 , and the backup battery  44  is charged. Also, the contact point  47   a  of the second relay  47  is connected and disconnected by the control of the controller  42 . The contact point  47   a  is normally in the disconnected state (OFF state), and when a voltage is applied to the second relay  47  from the controller  42  the contact point  47   a  is turned ON, the contact point  47   a  is connected, and the main battery  50   a  and the inverter  43  are connected. 
     The output values of a hydraulic pressure sensor  36  that measures the output pressure of the hydraulic pump  32  provided in the hydraulic unit  30 , and the measured values of a current sensor  49  that measures the load current supplied to the inverter  43  from the main battery  50   a  are input to the controller  42 . Also, the power source monitoring controller  41  includes a first pilot lamp  41   a  that indicates the ON state of the first relay  46 , in other words, the state in which electric power is being supplied to the controller  42 , and a power supply switch  41   b  that turns the first relay  46  ON when pressed while the first relay  46  is in the OFF state, and a warning pilot lamp  52  for notifying that a fault has arisen in the main battery unit  50 . Further, the controller  42  includes a second pilot lamp  42   a  that indicates the ON state of the second relay  47 , in other words, indicates that electric power is being supplied to the inverter  43 , and a motor start up switch  42   b  which when pressed while the second relay  47  is in the OFF state turns the second relay  470 N. The first and second pilot lamps  41   a ,  42   a , the warning pilot lamp  52 , the electric power switch  41   b , and the motor start up switch  42   b  are disposed within the operator&#39;s cabin  15 . 
     Next, control of the electric power supply by the power supply system  40  is explained using  FIG. 3 . First, the power supply start up process is explained. When the operator positioned in the operator&#39;s cabin  15  turns on the key switch  45 , which is disposed within the operator&#39;s cabin  15 , electric power is supplied from the backup battery  44  to the power source monitoring controller  41 , and the power source monitoring controller  41  starts up (step S 100 ). The power source monitoring controller  41  first supplies electric power to the protective circuit  50   b  of the main battery unit  50  to start up the protective circuit  50   b , and the protective circuit  50   b  starts and obtains the status of the main battery  50   a  (step S 110 ). Then the power source monitoring controller  41  obtains the status of the main battery  50   a  from the protective circuit  50   b  (step S 120 ), and determines whether the main battery  50   a  can be used or not (step S 130 ). For example, if the main battery  50   a  is excessively discharged or the like, it is determined that the main battery  50   a  cannot be used, so the power source monitoring controller  41  lights the warning pilot lamp  52 , and the power supply start up process is terminated (step S 160 ). 
     On the other hand, when it is determined that the main battery  50   a  is in the normal state and can be used, the power source monitoring controller  41  turns the first relay  46  ON, and electric power is supplied from the main battery  50   a  to the controller  42 , so the controller  42  is started, and the first pilot lamp  41   a  is lit (step S 140 ). As stated above, when the first relay  46  is in the ON state, electric power is supplied from the DC-DC converter  48  to the power source monitoring controller  41  and the backup battery  44 , and subsequently the power source monitoring controller  41  operates with electric power supplied from the DC-DC converter  48 , and charging of the backup battery  44  starts. 
     Finally, when the controller  42  has started, the controller  42  turns the second relay  470 N, electric power is supplied from the main battery  50   a  to the inverter  43 , the inverter  43  is controlled to supply the electric motor  31  with alternating current electric power at a predetermined voltage and frequency, the electric motor  31  starts up, the second pilot lamp  42   a  is lit (step S 140 ), and the electric power startup process of the power supply system  40  is terminated. 
     Next, the electric power saving control by the power supply system  40  is explained using  FIG. 4 . The electric power saving control is a control to prevent waste of electric power in the charged main battery  50   a  when it is not necessary to supply hydraulic oil to the hydraulic actuator  20 , by stopping the electric motor  31 , and stopping the controller  42 .  FIG. 4  shows the control by the controller  42 , and when the power supply start up process has terminated as described above, the electric power saving control is started. Also, the symbol A enclosed within a circle appealing after step S 240  in  FIG. 4  means go to and connect with the symbol A enclosed within a circle appearing immediately after Start. 
     The controller  42  measures the output oil pressure and the load current using the hydraulic pressure sensor  36  and the current sensor  49  (step S 200 ). Then, it is determined whether within a set period of time (for example, five seconds) the output pressure or the load current have varied (step S 210 ), if there is a variation, the procedure returns to step S 200  and repeats this process. On the other hand, when there is no variation in the output pressure and the load current within the set period of time, the controller  42  turns the second relay  47  off, so the power supply to the inverter  43  is disconnected, the electric motor  31  stops, and the second pilot lamp  42   a  is turned off (step S 220 ). 
     Next, the controller  42  determines whether the motor start up switch  42   b  is turned ON or not (step S 230 ). When it is determined that the motor start up switch  42   b  is ON, the second relay  47  is turned ON, the electric motor  31  is started by supplying electric power to the inverter  43 , and the second pilot lamp  42   a  is lit (step S 240 ). Then, the procedure returns to step S 200 , and the above process is repeated. At step S 230 , when it is determined that the motor start up switch  42   b  is not on, the controller  42  obtains the state of manipulation of the operating device  14  or the like (step S 250 ), determines whether within a set period of time there has been a state of no manipulation or control (step S 260 ), and when there has not been a state of no manipulation or control the procedure returns to step S 230  and this process is repeated. 
     At step S 230 , when it is determined that the state of no manipulation or control has continued during the set period of time, the controller  42  transmits a command signal to the power source monitoring controller  41  (step S 270 ). Then, when the power source monitoring controller  41  receives the command signal from the controller  42 , the first relay  46  is turned off, the electric power supply to the controller  42  is turned off and the controller  42  is stopped, first pilot lamp  41   a  is turned off, the electric power supply to the protective circuit  50   b  of the main battery unit  50  is stopped, and the sleep mode is activated. 
     When the sleep mode is activated, the power source monitoring controller  41  stops operation except for monitoring whether the power supply switch  41   b  has been pressed, so the electric power consumption of the backup battery  44  is minimized as much as possible. Then, when it is detected that the power supply switch  41   b  has been pressed, the power source monitoring controller  41  terminates the sleep mode, implements the process from step S 110  in the power supply start up process shown in  FIG. 3 , the first and second relays  46 ,  47  are turned on, electrical power is supplied to the controller  42  and the inverter  43 , and the electric motor  31  is started. 
     In this way, by providing the power source monitoring controller  41  that controls the supply of electric power to the inverter  43  separately from the controller  42 , monitors the main battery unit  50 , as well as controls the supply of electric power to the controller  42 , and the backup battery  44  that allows the power source monitoring controller  41  to operate even when electric power is not supplied from the main battery unit  50 , even if a fault arises in the main battery  50   a , this fault is detected by the power source monitoring controller  41  and it is possible to provide a warning using the warning pilot lamp  52  or the like, so it is possible to make the operator that is operating the power shovel  1  immediately aware of the fault in the main battery unit  50 . 
     At this time, the process when electric power is turned ON as described above is capable of turning on the power supply in turn starting with the power source monitoring controller  41 , so it is possible to simplify the process and constitution of the power source monitoring controller  41  and the controller  42 . Also, when electric power is supplied to the controller  42  when the main battery  50   a  is in a normal state, and at the same time the power source monitoring controller  41  is operated by the main battery  50   a  and the backup battery  44  is charged, if a fault arises in the main battery  50   a , the power source monitoring controller  41  can be operated by the backup battery  44 . 
     Further, the supply state of hydraulic oil to the hydraulic actuator  20  and the manipulation state of the operating device  14  are monitored by the controller  42 , and when oil pressure is not necessary the electric power supply to the inverter  43  is stopped, and further the electric power supply to the controller  42  is stopped, so unnecessary power consumption from the main battery  50   a  is minimized, and it is possible to lengthen the time that the power shovel  1  can carry out work without charging the main battery unit  50 . Even when the power supply to the inverter  43  and the controller  42  is stopped in this way, by pressing the motor start up switch  42   a  or the power supply switch  41   a , it is possible to simply supply electric power to the inverter  43  and the controller  42 .