JP2008303058A - Work vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a work vehicle mounted with a power source controller capable of certainly controlling discharging and charging. <P>SOLUTION: The work vehicle comprises first and second battery modules 43, 44, and the power source controller capable of controlling the charging/discharging thereof. The power source controller comprises a system voltage line 62 to which the first and second battery modules 43, 44 are connected; a power supply circuit 74 switching whether the first and second battery modules 43, 44 are connected to the system voltage line 62 in series or in parallel; and a controlling portion 77 controlling switching by the power supply circuit 74 so as to make the connection relationship parallel when the first and second battery modules 43, 44 are charged, and controlling switching by the power supply circuit 74 in a switching period corresponding to the total voltage of the first and second battery modules 43, 44 when they are discharged. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a work vehicle using a battery as a drive source.

  Conventionally, a battery forklift using a battery as a driving source is known (for example, Patent Document 1). A battery mounted on such a forklift is designed exclusively for a work vehicle and is composed of a single cell. The output voltage of one battery is about 2V. Usually, 24 batteries are connected in series to obtain a voltage of 48V.

  However, the battery for a work vehicle is one large, and when 24 batteries are mounted, the current situation is that the design on the vehicle side must be sacrificed because of the need to secure the arrangement space.

  On the other hand, there is an electric vehicle as a vehicle using a battery as a drive source (for example, Patent Document 2). Many batteries mounted on electric vehicles are composed of a plurality of cells, and one battery outputs a voltage of 12V. Therefore, it is possible to obtain a voltage of 48V by connecting four batteries in series. Moreover, since the battery of an electric vehicle is smaller than the battery of a work vehicle, the degree of freedom in designing the vehicle is reduced. Increase.

JP 2006-264940 A JP-A-5-193367

  However, since a battery for an electric vehicle has a small capacity, it cannot be applied to a work vehicle simply by connecting a plurality of batteries in series to obtain a predetermined voltage. That is, in order to apply to a work vehicle, it is necessary not only to connect a plurality of batteries in series but also to connect the batteries in parallel in order to obtain a required capacity. In a battery-powered vehicle, discharging and charging are repeated, so that a power supply controller that supports such series-parallel battery connection and reliably controls discharging and charging is required.

  The objective of this invention is providing the work vehicle carrying the power supply controller which can control discharge and charge reliably.

A work vehicle according to a first aspect of the present invention includes at least a pair of battery modules and a power supply controller that controls charging and discharging in these battery modules, and the power supply controller is connected to the pair of battery modules. A power supply circuit for switching whether to connect the system voltage line and the pair of battery modules to the system voltage line in a serial relationship or to connect to the system voltage line in a parallel relationship, and charging of the pair of battery modules In the case of performing the control, switching in the power supply circuit is controlled so that the connection relation of the pair of battery modules is parallel, and in the case of discharging the pair of battery modules, the total of the pair of battery modules A control unit that controls switching in the power supply circuit at a switching cycle according to voltage. And said that you are.
Here, “connected in series” and “connected in parallel” refer to electrical connection between the battery modules.

    The work vehicle according to claim 2 is the work vehicle according to claim 1, wherein the power controller is attached to an upper portion of a battery unit main body including the at least one pair of battery modules, and the battery. The module is characterized in that a plurality of batteries are connected in series.

  A work vehicle according to a third aspect is the work vehicle according to the second aspect, wherein a plurality of the battery modules are vertically stacked in the battery unit main body.

  According to the first aspect of the present invention, the control unit of the power supply controller controls the power supply circuit so that the connection form to the system voltage line of each battery module is appropriate at the time of discharging and charging. The voltage from the module can be reliably output to the system voltage line, and the charging power from the external power source or the like can be reliably charged for each battery module. In addition, when the total voltage in the battery modules decreases, the power supply circuit is controlled so that the ratio of connecting each battery module in series is increased, so that each other's voltage can be compensated for over a long period of time. A stable voltage can be output.

  According to the invention of claim 2, the battery module is constituted by a plurality of batteries. However, as the battery in the present invention, one for an electric vehicle can be applied. Accordingly, even if a plurality of such batteries are connected in series to form each battery module, the size of the battery unit body does not become excessively large, and the power supply controller can be securely attached to the upper part of the battery unit body. . Furthermore, when changing the specifications by changing the number of batteries, etc., it is also necessary to change the specifications on the power supply controller side, but since the battery unit body and the power supply controller are provided integrally, They can be easily integrated and removed, and maintenance and the like can be facilitated.

  According to the third aspect of the present invention, the battery modules are stacked one above the other, so that a smaller arrangement space may be required in plan view. For example, the battery unit main body and The power supply controller can be accommodated integrally, and the present invention can be applied without significantly changing the design of the vehicle body. In other words, since the arrangement space for the battery unit main body and the power supply controller can be reduced, the degree of design freedom on the vehicle body side can be increased accordingly.

[Schematic configuration of forklift]
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a side view showing an entire forklift 10 as a work vehicle according to the present embodiment. The forklift 10 is a four-wheel type equipped with left and right front wheels 12 and rear wheels 13 on the front and rear of a vehicle body 11, respectively, and is a battery forklift driven by electric energy from a battery. However, the forklift of the present invention may be a three-wheel type having only one rear wheel 13.

  On the front side of the vehicle body 11, a work machine 14 for cargo handling is provided. The work machine 14 has a mast 15 erected vertically, a fork claw 16 that moves up and down along the mast 15, a lift cylinder 17 that drives the fork claw 16 up and down, and an entire work machine 14 with respect to the vehicle body 11. And a tilt cylinder 18 that tilts back and forth within an angular range.

  The vehicle body 11 is provided with a driver seat 19 for an operator to sit on. The upper side of the driver seat 19 is covered with a head guard 20 attached on the vehicle body 11. The driver's seat 19 is provided integrally with the lower hood panel 21. The hood panel 21 is provided so as to be openable and closable up and down, and a battery unit 30 is accommodated below the hood panel 21. The battery unit 30 can be slid in the horizontal direction with respect to the vehicle body 11 by opening and closing a side panel that can also be opened and closed, and can be easily attached and detached.

  A counterweight 22 is provided on the rear side of the vehicle body 11. The space inside the counterweight 22 accommodates a main controller 23, a capacitor 24, and the like. The main controller 23 supplies the electric energy from the battery unit 30 to the electric motor 25 for driving the front wheels 12 (FIG. 5) and the electric motor 26 for the work implement 14 (FIG. 5). In particular, since the capacitor 24 has a relatively large weight, the capacitor 24 has a role as a part of the counterweight 22 by being accommodated in the counterweight 22.

[Configuration of battery unit]
Hereinafter, the battery unit 30 housed in the vehicle body 11 will be described in detail. 2 is an exploded perspective view showing a part of the battery unit 30 in an exploded manner, and FIG. 3 is an exploded perspective view showing the whole battery unit 30 in an exploded manner. FIG. 4 is a schematic diagram showing the accommodation state and connection state of the battery 34 in the battery unit 30.

  The battery unit 30 includes a battery unit main body 32 that includes a bottomed box-shaped battery case 31 and a power supply controller 33 that is mounted on the battery unit main body 32. Such a battery unit 30 has a shape and a size that are accommodated in a battery accommodating chamber of a conventional battery forklift. Therefore, a conventional vehicle body can be used as it is as the vehicle body 11. Of course, the vehicle body 11 may be designed exclusively for mounting the battery unit 30. In addition to the bottomed shape, the battery case 31 may have a bottomed shape as long as there is no problem in terms of strength and layout, or may be a hanging type or a cage type.

  The battery unit main body 32 has a structure in which a total of 24 batteries 34 are accommodated therein. However, the number of the batteries 34 is arbitrary, and may be determined in consideration of an output voltage required for the system of the forklift 10 as a whole, an output voltage of the battery 34 alone, or the like. 2 and 3, the battery 34 is indicated by a two-dot chain line. Specifically, the 24 batteries 34 are stacked and accommodated in three upper and lower stages as shown in FIG. That is, the battery unit main body 32 accommodates an upper bracket 35 positioned at the upper level, a middle bracket 36 positioned at the middle level, and a lower bracket 37 positioned at the lower level. Each bracket 35 to 37 accommodates eight batteries 34.

  The upper bracket 35 has a planar rectangular shape, and includes a bottomed frame body 38 that surrounds the four circumferences, and a partition panel 39 that partitions the inside of the frame body 38 along the long side direction. The first storage space 41 and the second storage space 42 are partitioned along the short side direction. Four batteries 34 are housed in the first housing space 41 and the second housing space 42, respectively. A first battery module 43 is formed by the battery 34 housed in the first housing space 41, and a second battery module 44 is formed by the battery 34 housed in the second housing space.

  Similarly, the middle bracket 36 is composed of a frame body 45 that surrounds the four circumferences, and a partition panel 46 that partitions the inside of the frame body 45 along the long side direction. It is partitioned into spaces 47 and 48. Four batteries 34 are also housed in the third and fourth housing spaces 47 and 48, respectively. A third battery module 49 is formed by the battery 34 housed in the third housing space 47, and a fourth battery module 51 is formed by the battery 34 housed in the fourth housing space 48.

  On the other hand, the lower bracket 37 has a rectangular shape with a deformed plane, and the inner side of the frame body 52 is arranged in the short side direction so as to contact the center partition panel 53 along the long side direction and both ends of the partition panel 53. It is comprised with a pair of partition panel 54 arrange | positioned along, and the inside is divided by these partition panels 53 and 54 into the 5th-8th accommodation space 55-58. Two batteries 34 are accommodated in the fifth to eighth accommodating spaces 55 to 58, respectively. The fifth battery module 59 is formed by the batteries 34 in the fifth and sixth housing spaces 55 and 56, and the sixth battery module 61 is formed by the batteries 34 in the seventh and eighth housing spaces 57 and 58. Is done.

  Here, the battery 34 is for an electric vehicle that is much smaller than a battery dedicated to a work vehicle, and one battery 34 has an output voltage of 12 V and can respond to rapid charging in a short time. The vertical dimension of the battery 34 is about the same as the vertical dimension of each bracket 35-37. The brackets 35 to 37 in which the battery 34 is accommodated are accommodated in the battery case 31 in order from the lower bracket 37 and stacked one above the other. At this time, means for preventing the brackets 35 to 37 from being displaced from each other may be provided as appropriate.

  In FIG. 4, in the first battery module 43, four batteries 34 are arranged in pairs along the short side and the long side, and are connected in series. Such arrangement and connection are the same in the second to fourth battery modules 44, 49, 51. On the other hand, the fifth and sixth battery modules 59 and 61 have a planar bowl shape. The four batteries 34 in the fifth and sixth battery modules 59 and 61 are also connected in series.

  As described above, the reason why the battery arrangement in the fifth and sixth battery modules 59 and 61 in the lower stage is different from the battery arrangement in the middle stage and the upper stage is to correspond to the structure on the vehicle body 11 side. Since the size of the battery 34 itself is small, the structure of the vehicle body 11 can be easily accommodated by devising the arrangement. On the other hand, the vehicle body 11 can be designed with a high degree of freedom without being limited by the arrangement of the battery 34. The first to sixth battery modules 43, 44, 49, 51, 59, 61 may all have the same battery arrangement. In such a case, the same shape can be used as the brackets 35-37 used. The shapes of the brackets 35 to 37 are not limited to those having the bottomed frames 38, 45, and 52 as illustrated, but are arbitrary.

[Forklift system configuration]
Next, the system configuration of the forklift 10 will be described below with a focus on the power supply controller 33. FIG. 5 is a block diagram showing the entire system, and FIG. 6 is a circuit diagram showing a circuit of a main part of the system. The power supply controller 33 of the forklift 10 is provided with a DC 48V system voltage line 62 to which a power supply line from the battery unit main body 32 is connected. The system voltage line 62 is connected to the main controller 23, the capacitor 24, the proportional valve controller 64, and the meter panel 65 via the connector 63, and supplies power from the battery unit 30.

  The main controller 23 controls the electric motor 25 for driving the front wheels 12 (FIG. 1) based on an operation signal from a travel pedal (not shown), and also controls the electric motor 26 for driving the hydraulic pump 66. These electric motors 25 and 26 correspond to loads in the present invention. The hydraulic pump 66 supplies hydraulic pressure to the lift cylinder 17 and the tilt cylinder 18 via the proportional valve 67. Further, when the electric motor 26 functions as a generator, the main controller 23 sends the electric energy regenerated by the electric motor 26 to the capacitor 24 to be stored.

  The capacitor 24 has a characteristic capable of efficiently collecting, storing and discharging a large current generated instantaneously, and can utilize regenerative energy without loss. Thus, the capacitor 24 functions as a power source together with the battery unit 30 and assists in driving the electric motors 25 and 26. In other words, this system is a battery hybrid having two power sources, that is, the battery unit 30 side and the capacitor 24 side.

  The proportional valve controller 64 energizes the solenoid of the proportional valve 67 based on an operation signal from an unillustrated work machine operation lever, and switches the spool position of the proportional valve 67. As a result, the cylinders 17 and 18 can be expanded and contracted by the hydraulic pressure from the hydraulic pump 66 to perform the cargo handling operation.

  A battery charging line 68 is also connected to the system voltage line 62 of the power controller 33. External power from the AC input unit 69 is input to the charging line 68 via the charge contactor 71. The input AC power is converted to DC by the converter 72, and is stepped down to a charging voltage by the transformer 73 and energized to the system voltage line 62.

  Charging of the battery unit main body 32 with electric power input to the system voltage line 62 and discharging from the battery unit main body 32 are performed by the first to third power supply circuits 74 to 76 in the power supply controller 33 and a control unit 77 including a CPU. The discharge voltage maintaining means 78 and the circuit switching instructing means 79 are controlled. These discharge voltage maintaining means 78 and circuit switching instruction means 79 are actually software executed in the control unit 77.

  The power lines from the first to third power supply circuits 74 to 76 are connected to the system voltage line 62 in parallel with each other. The first power supply circuit 74 has power cables from the first and second battery modules 43 and 44, the second power supply circuit 75 has power cables from the third and fourth battery modules 49 and 51, and the third power supply circuit. The power cables from the fifth and sixth battery modules 59 and 61 are detachably connected to 76 via connectors (not shown).

  The first to third power supply circuits 74 to 76 are controls for switching the parallel connection between the first and second battery modules 43 and 44 to the serial connection as shown by the first power supply circuit 74 in FIG. Circuit. In the first power supply circuit 74 shown in FIG. 6, the first and second battery modules 43 and 44 are connected to the system voltage line 62 in parallel with each other, and the first and second batteries are connected. A bypass line 81 for connecting the modules 43 and 44 in series is provided. The bypass line 81 is provided with a transistor 82. The transistor 82 functions as an on / off switch of the series-parallel chopper circuit.

  In addition, a first diode 85 having a forward direction from the negative contact 62B side to the first battery module 43 side is provided between the negative side of the first battery module 43 and the negative contact 62B of the system voltage line 62. Is provided. Between the positive side of the second battery module 44 and the positive contact 62A of the system voltage line 62, there is provided a second diode 86 whose forward direction is from the second battery module 44 side to the positive contact 62A side. Yes.

  A third diode 87 is connected between the collector and emitter of the transistor 82. The direction of the third diode 87 from the first battery module 43 side to the second battery module 43 side is the forward direction. That is, in the transistor 82 and the third diode 87, the direction of current flow is set in reverse.

  Further, a transistor 83 is connected before and after the first diode 85, and a transistor 84 is also connected before and after the second diode 86. In the first diode 85 and the transistor 83, the direction of current flow is opposite, and in the second diode 86 and the transistor 84, the direction of current flow is also opposite.

  An inductance (coil) 88 is provided between the first battery module 43 and the positive contact 62A, and an inductance (coil) 89 is provided between the second battery module 44 and the negative contact 62B.

  The discharge voltage maintaining means 78 in the control unit 77 detects the voltages at the first to sixth battery modules 43, 44, 49, 51, 59, and 61, and at the time of discharging, the first to third power supplies. A voltage of 48V is always generated in the circuits 74 to 76 (actually 50 V in consideration of a margin, but here it is unified with 48V for convenience of explanation) and supplied to the system voltage line 62 to supply the system voltage line. 62 is controlled to be maintained at 48V. Further, when it is detected that the first to sixth battery modules 43, 44, 49, 51, 59, 61 have been discharged and each voltage has fallen below the lower limit specified value, the control is stopped.

  Specifically, based on FIG. 6 and FIG. 7, in the discharge control, the discharge voltage maintaining means 78 turns off the transistors 83 and 84 and based on the total voltage at the first and second battery modules 43 and 44. The chopper control of the transistor 82 is performed at the ratio of the ON signal determined by the above. That is, a signal that repeats the on / off operation is output to the base of the transistor 82 at a predetermined cycle (switching cycle). However, when the total voltage is sufficiently large, the ratio of the on signal within one cycle (1 The ratio of the ON signal within the period) is reduced. By doing so, it takes a long time to turn off all the transistors 82, 83, 84, so that the first and second battery modules 43, 44 are connected to the system voltage line 62 in parallel with each other. . Therefore, each voltage (for example, 48V) in the first and second battery modules 43 and 44 is output to the system voltage line 62 as it is.

  On the other hand, when each voltage in the first and second battery modules 43 and 44 decreases, the discharge voltage maintaining means 78 increases the ratio of the on signal in the signal that repeats the on / off operation with respect to the base of the transistor 82. To do. In the state where the ON signal is output, the first and second battery modules 43 and 44 are connected in series with each other, so that the mutual voltage is compensated and the compensated voltage is output to the system voltage line 62. The Therefore, when each voltage drops, an on / off signal with a proportion of the on signal corresponding to the total voltage may be output, and the first power supply circuit 74 reliably outputs 48V obtained by compensating each other. it can. That is, when the voltage drop is significant, 48V can be reliably output by increasing the ratio of the ON signal. And when each voltage of the 1st, 2nd battery modules 43 and 44 is less than a regulation value, since charge is required, discharge control is stopped.

  The circuit switching instruction unit 79 has a function of switching the first to third power supply circuits 74 to 76 for charging the first to sixth battery modules 43, 44, 49, 51, 59, 61. As the case of charging, firstly, the capacitor 24 side is charged to a predetermined voltage or more, and the discharge control is stopped by lowering the generated regenerative energy below the lower limit specified value. This is a case where one of the sixth battery modules 43, 44, 49, 51, 59, 61 is charged.

  For example, in FIG. 6, when each voltage of the first and second battery modules 43 and 44 falls below the lower limit specified value and the discharge control is stopped, the regenerative energy surplus in the capacitor 24 is the system voltage line. 62 is output. Therefore, the circuit switching instruction means 79 turns off the transistor 82 and turns on the transistors 83 and 84, respectively. Then, on the first battery module 43 side, a current flows from the positive contact 62A to the negative contact 62B through the first battery module 43 and the transistor 83, and charging is performed in the first battery module 43. On the second battery module 44 side, the current flows from the positive contact 62A to the negative contact 62B through the transistor 84 and the second battery module 44, and charging is performed in the second battery module 44. Therefore, in such charging, charging in units of the first to sixth battery modules 43, 44, 49, 51, 59, 61 is possible.

  The second charging is rapid charging from an external power source performed through the AC input unit 69. Also in this case, the circuit switching instruction means 79 turns off the transistor 82 and turns on the transistors 83 and 84, respectively. Similarly, on the first battery module 43 side, current flows from the positive contact 62A through the first battery module 43 and the transistor 83 to the negative contact 62B, and the first battery module 43 performs quick charging. Also on the second battery module 44 side, the current flows from the positive contact 62A through the transistor 84 and the second battery module 44 to the negative contact 62B, and the second battery module 44 performs quick charging. Accordingly, even with such charging, quick charging in units of the first to sixth battery modules 43, 44, 49, 51, 59, 61 is possible.

  Here, since the power supply controller 33 is a three-channel type having the first to third power supply circuits 74 to 76, a maximum of six battery modules (first to sixth battery modules 43, 44, 49, 51, 59, 61) can be connected. In this embodiment, the case where all three channels are used is illustrated. However, in the power supply controller 33, the number of battery modules connected can be varied according to the model (class) divided by the maximum load in the specifications of the forklift 10 or the like.

  For example, although the maximum load is not different from that of the forklift 10 of the present embodiment, the first to fourth battery modules 43 using the upper and middle stages of the battery unit main body 32 are used in a model exclusively used for a short time cargo handling operation. , 44, 49, 51 are mounted, and these may be connected to the first and second power supply circuits 74, 75. In such a case, the first and second channels are used, and the third channel is not used. The battery 34 is not accommodated in the lower bracket 37, and there is an empty space. Alternatively, only the upper first battery modules 43 and 44 can be mounted and connected to the first power supply circuit 74 for use. In this case, only one channel is used, and the battery 34 is not accommodated in the middle and lower brackets 36 and 37.

  On the contrary, it is possible to cope with a case where a higher output voltage than 48V is required or a lower output voltage is required. For example, if two of the eight batteries 34 constituting the lower fifth and sixth battery modules 59 and 61 are connected in series to the first to fourth battery modules 43, 44, 49 and 51, respectively, Each of the first to fourth battery modules 43, 44, 49, and 51 is composed of six batteries 34, and an output voltage of 72V can be obtained. Even in this case, the first and second channels are used, and the third channel is not used. Of course, if the first to fourth battery modules 43, 44, 49, 51 are constituted by five batteries 34, 60V can be obtained. In this case, the third channel is not used and half of the lower bracket 37 is It becomes an empty space.

  To achieve a lower output voltage, simply reduce the number of batteries 34 connected in series. The empty space according to the reduced number will arise in each bracket 35-37. For example, each of the first to sixth battery modules 43, 44, 49, 51, 59, 61 is configured by the maximum number of four batteries 34 in the present embodiment, but is not more than three batteries 34. The output voltage of 12V, 24V, and 36V can be obtained by carrying out like this. Even in such a case, the number of channels to be used may be determined by performing parallel connection according to the required capacity.

  That is, the first to third power supply circuits 74, 75, and 76 are provided for the three channels in the power supply controller 33 of the present embodiment, but whether to use all or a part of them is used. Again, it depends on the required output voltage and capacity. It should be noted that the maximum number of power supply circuits to be provided in the power supply controller 33 is arbitrary, and is not limited to 3 as in the present embodiment, but may be four or more, or in short, a plurality of I just need it.

  Returning to FIG. 5, in the forklift 10 of the present embodiment, the precharge switch 91, the charging operation panel 92, the state display means 93, and the hood switch 94 are connected to the control unit 77 of the power controller 33.

  The precharge switch 91 is a switch for performing precharge from the battery unit main body 32 to the capacitor 24. When the system is turned on by operating the key switch to the on position, first, the control unit 77 detects and compares the voltage on the capacitor 24 side and the voltage on the battery unit body 32 side, and the voltage on the capacitor 24 side is compared with the battery unit. When the voltage is lower than the voltage on the main body 32 side and the difference is not less than the specified value, the main contactor 95 is opened. This is because if the main contactor 95 is energized while the voltage on the capacitor 24 side is low, current may flow from the battery unit body 32 to the capacitor 24 at a stretch, and damage may occur at the contacts on the electric circuit.

  Therefore, it is necessary to charge the capacitor 24 to reduce the voltage difference (potential difference) from the battery unit main body 32 side while maintaining the main contactor 95 in the open state. For this reason, in this embodiment, a precharge circuit (not shown) that bypasses the main contactor 95 in the open state is provided, and by operating the precharge switch 91, a minute current is caused to flow through the precharge circuit. The capacitor 24 is charged from the main body 32 to reduce the voltage difference between the two. If the precharge is not performed and the voltage on the capacitor 24 side remains low, the main controller 23 and the meter panel 65 do not start.

  The charging operation panel 92 is operated when charging the battery unit main body 32 through the AC input unit 69. Charging is started by connecting an external power source to the AC input unit 69 and operating the charging operation panel 92. The state of charge such as the amount of charge can be determined by lighting of an LED or the like provided on the charging operation panel 92, an alarm, or the like.

  The status display means 93 is a means for displaying the status of the system before startup. When the key switch for starting the system is operated to the on position, only a part including the control unit 77 of the power controller 33 is started, and charging is performed by comparing the voltage on the capacitor 24 side with the voltage on the battery unit body 32 side. The state is determined, and when pre-charging is necessary, pre-charging is started, and the fact that pre-charging is being performed is displayed by blinking of a green LED provided in the state display means 93 or the like. In addition, the control unit 77 detects other abnormalities such as, for example, a poor fitting of the connector 63. If there is a poor fitting, the control unit 77 sends a signal to that effect to the status display means 93. And displayed by lighting the red LED. The means for notifying the state may be a means using an alarm, sound or the like in addition to a light emitting element such as an LED.

  The hood switch 94 is a limit switch attached to a hinge portion for opening and closing the hood panel 21, and an output corresponding to the open / closed state of the hood panel 21 is recognized by the control unit 77. When the battery unit main body 32 is charged by an external power source, the hood panel 21 must be kept open because of the need for ventilation around the battery unit 30. For this reason, in the control unit 77, when it is determined that the hood panel 21 is closed based on the on / off state of the hood switch 94, control is performed to open the charge contactor 71 so that charging cannot be performed. The red LED of the display means 93 is turned on.

[Charge / discharge control flow]
Next, control during discharging from the battery unit main body 32 will be described with reference to FIGS. 6 and 7. Hereinafter, the case of discharging from the first and second battery modules 43 and 44 will be described, but the same applies to the third to sixth battery modules 49, 51, 59, and 61.

In the discharging power supply controller 33, the discharge voltage maintaining means 78 of the control unit 77 keeps all the transistors 82, 83, 84 of the first control circuit 74 off, and always the first battery module 43 and the second battery module. The voltages V _M1 and V _M2 at 44 are acquired (S1), and whether the voltages V _M1 and V _M2 are smaller than the lower limit stipulated value V _L (S2). Otherwise, the total voltage of both is calculated (S3).

After calculating the total voltage of the voltages V _M1 and V _M2 , the discharge voltage maintaining means 78 calculates the ratio of the ON signal of the transistor 82 according to the total voltage (S4), and the ON / OFF signal of this ratio is converted to the transistor at a high speed cycle. It outputs to 82 and drives (S5).

  Thereby, even if the voltage of the 1st, 2nd battery modules 43 and 44 is lower than 48V, since a voltage is mutually compensated, 48V can be reliably supplied to the system voltage line 62. FIG.

  Next, charging control for the battery unit main body 32 when an external power source is used will be described with reference to FIGS. In the following, the case of discharging to the first and second battery modules 43 and 44 will be described, but the same applies to the third to sixth battery modules 49, 51, 59 and 61.

When the charging operation panel 92 is operated, in the power controller 33, the circuit switching instruction means 79 of the control unit 77 first turns off the transistor 82 in the bypass line 81 and turns on the other transistors 83 and 84 (S11). Thus, while detecting the voltages V _M1 and V _M2 in the first and second battery modules 43 and 44, the charging is continued until the upper limit value V _U is exceeded (S12).

  Thereby, the battery 34 which comprises the 1st-6th battery modules 43, 44, 49, 51, 59, 61 can be charged reliably and in a short time in units of the battery modules.

The best configuration, method, and the like for carrying out the present invention have been disclosed above, but the present invention is not limited to this. That is, the invention has been illustrated and described with particular reference to certain specific embodiments, but without departing from the spirit and scope of the invention, Various modifications can be made by those skilled in the art in terms of quantity and other detailed configurations.
Therefore, the description limited to the shape, quantity and the like disclosed above is an example for easy understanding of the present invention, and does not limit the present invention. The description by the name of the member which remove | excluded the limitation of one part or all of such restrictions is included in this invention.

  For example, the forklift 10 of the above embodiment is a counter type provided with the counterweight 21, but the present invention is not limited to this, and the present invention may be applied to a reach type forklift.

  The present invention can be used for work vehicles such as a forklift driven by electric energy from a battery, a small hydraulic excavator, and a wheel loader.

The side view which shows the whole working vehicle which concerns on one Embodiment of this invention. The disassembled perspective view which decomposes | disassembles and shows a part of battery unit. The exploded perspective view which decomposes | disassembles and shows the whole battery unit. The schematic diagram which shows the accommodation state and connection state of the battery in a battery unit. The block diagram which shows the whole system of the working vehicle of the said embodiment. The circuit diagram which shows the circuit of the principal part of a system. The flowchart for demonstrating discharge control. The flowchart for demonstrating charge control.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Forklift which is a working vehicle, 32 ... Battery unit main body, 33 ... Power supply controller, 34 ... Battery, 43, 44, 49, 51, 59, 61 ... First to sixth battery modules which are battery modules, 62 ... System Voltage line 77... Control unit 78. Discharge voltage maintaining means 79 79 Circuit switching instruction means.

Claims (3)

At least a pair of battery modules;
A power supply controller for controlling charging and discharging in these battery modules,
The power controller includes a system voltage line to which the pair of battery modules are connected,
A power supply circuit that switches between connecting the pair of battery modules to the system voltage line in a serial relationship or connecting to the system voltage line in a parallel relationship;
When charging the pair of battery modules, controlling the switching in the power supply circuit so that the connection relationship between the pair of battery modules is parallel, and when discharging the pair of battery modules, A work vehicle comprising: a control unit that controls switching in the power supply circuit at a switching cycle according to a total voltage of the pair of battery modules. The work vehicle according to claim 1,
The power controller is integrally attached to a battery unit main body configured to include the at least one pair of battery modules,
The battery module includes a plurality of batteries connected in series. The work vehicle according to claim 2,
In the battery unit main body, a plurality of the battery modules are stacked one above the other.

Images