JP2012065402A - Electric assist truck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric assist truck which conducts charging safety.SOLUTION: In an electric assist truck, power is assisted by electric motors 51 and 52. The electric assist truck includes a plug 62 connected to an external electric power source 79, a charger 70 converting alternating current supplied through the plug 62 to direct current to output the direct current, a charging circuit 65 leading the direct current output from the charger 70 to a battery 75, an output circuit 66 outputting electric power accumulated in the battery 75 to the electric motors 51 and 52, and a switch 80 shutting off the output circuit 66 during charging.

Description

  The present invention relates to an electric assist cart that conveys a load when pushed by an operator.

  Generally, when a heavy load is placed on a trolley used in a factory or the like, the worker needs to push the trolley with great force.

  As countermeasures, for example, Patent Documents 1 and 2 propose an electric assist cart that detects the force of an operator who pushes the cart and is provided with auxiliary power according to human power by an electric motor.

JP 2006-290319 A JP 2007-176195 A

  However, in such a conventional electric assist cart, when charging the battery, for example, the battery is removed from the cart and connected to an external charger, or the battery is mounted on the cart and dedicated charging is performed. The battery must be connected to the battery, making it difficult to charge safely.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide an electric assist cart that can be charged safely.

  The present invention is an electric assist cart whose power is assisted by an electric motor, and a plug connected to an external power source, and a charge that converts an alternating current supplied through the plug into a direct current and outputs the direct current , A charging circuit for directing a direct current output from the charger to the battery, an output circuit for outputting the electric power stored in the battery to the electric motor, and a switch for cutting off the output circuit during charging It was. .

  According to the present invention, when the alternating current is supplied to the charger and the battery is charged with the direct current output from the charger, the output circuit is cut off, so that the direct current output from the charger is the left and right electric motors. Can be safely charged.

The perspective view of the electrically assisted trolley | bogie which shows embodiment of this invention. The side view of an electric assist cart. The top view of an electric assist cart similarly. The front view of an electric assist cart. The schematic block diagram of a raising / lowering apparatus similarly.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  The electric assist cart 1 shown in FIGS. 1 to 4 is used to carry heavy objects, for example, in a factory. When the electric assist cart 1 is pushed and moved by an operator, auxiliary power is applied by electric motors 51 and 52 (see FIG. 5).

  The electric assist cart 1 includes a traveling frame 2 provided as a main body thereof, a cargo bed 3 provided on the traveling frame 2, caster wheels 4 of casters 40 provided at a front portion of the traveling frame 2, and left and right of the traveling frame 2. The left and right drive wheels 5 provided at the side portions and the operation handle 8 provided at the rear of the cargo bed 3 are provided.

  A rear frame 11 is coupled to the traveling frame 2, and an operation handle 8 is supported on the rear frame 11.

  The electric assist cart 1 controls the electric power supplied to the left and right electric motors 51 and 52 from the left and right electric motors 51 and 52 (see FIG. 5) and the batteries (not shown) respectively driving the left and right drive wheels 5. And a controller (not shown) for controlling the outputs of the left and right electric assist carts according to the operation force of the operator pushing the operation handle 8 so that the left and right drive wheels 5 are powered. ing.

  The electric assist cart 1 includes a front-rear direction torque sensor 9 that detects torque around the horizontal axis generated in the operation handle 8 as an operation force detection unit that detects the magnitude and direction of the force with which the operator pushes the operation handle 8, and an operation handle. And a turning direction torque sensor 10 that detects torque around the vertical axis.

  The controller controls the left and right electric motors 51 and 52 to generate power corresponding to the torque values detected by the front-rear direction torque sensor 9 and the turning direction torque sensor 10, respectively, and moves the electric assist cart 1 forward or backward. A driving force is applied to move straight, turn, and bend.

  A front frame 12 is coupled to the traveling frame 2, and a caster 40 is supported on the front frame 12.

  As shown in FIG. 2, the caster 40 includes a caster wheel 4 that is in rolling contact with a road surface, a wheel shaft 41 that rotatably supports the caster wheel 4, an arm 42 that supports the wheel shaft 41, and a base end of the arm 42. And a pivot bracket 43 that supports the pivotable portion about a horizontal axis. The pivot bracket 43 is pivotally supported about a pivot axis T4 (see FIG. 3).

  In the caster 40, the turning axis T4 and the wheel shaft 41 of the turning bracket 43 are offset in the horizontal direction, and the caster wheel 4 is caused by the rolling frictional resistance of the caster wheel 4 as the electric assist cart 1 moves in either the front, rear, left, or right direction. The turning bracket 43 is turned to turn, and the caster wheel 4 is steered so as to face the traveling direction.

  A damper rubber (spring) 44 (see FIG. 3B) is interposed between the arm 42 and the turning bracket 43, so that the vertical vibrations of the caster wheels 4 due to road surface irregularities and the like are mitigated and absorbed, and vibrations are generated. Transmission to the traveling frame 2 can be suppressed.

  An elevating device 60 is provided between the traveling frame 2 and the loading platform 3. The lifting device 60 lifts and lowers the cargo bed 3 by an electric lifting cylinder (not shown). For example, when a heavy object is placed on the loading platform 3 and the caster 40 and the suspension device 20 sink, the lifting device 60 raises the loading platform 3 and adjusts the height of the loading platform 3 with respect to the road surface to be substantially constant. Yes.

  The left and right drive wheels 5 are supported by the traveling frame 2 so as to be able to move up and down via a suspension device 20 to be described later, and the vertical vibrations of the drive wheels 5 due to road surface irregularities and the like are reduced and absorbed, and the vibrations are transmitted to the traveling frame 2. Can be suppressed.

  FIG. 3A is a plan view of the electric assist cart 1 as viewed from above, and FIG. 3B is a plan view of the electric assist cart 1 as viewed from below.

  The loading platform 3 is provided so as to cover substantially the entire area above the traveling frame 2, casters 40, and left and right drive wheels 5. A load is directly placed on the loading platform 3. In addition, a roller conveyor (not shown) may be installed on the traveling frame 2 instead of the cargo bed 3, and the luggage may be placed via the roller conveyor.

  The electric assist cart 1 is provided with a single caster wheel 4 at the front center. The pivot axis T4 of the caster wheel 4 is disposed on a center line Ox extending in the front-rear direction of the loading platform 3 and the traveling frame 2.

  The present invention is not limited to this, and the left and right (two) caster wheels may be provided on the electric assist cart 1. In this case, the turning shafts of the left and right caster wheels are arranged so as to be equidistant in the left-right direction from the center line extending in the front-rear direction of the loading platform 3 and the traveling frame 2.

  The wheel rotation shafts of the left and right drive wheels 5 are arranged closer to the wheel rotation shafts of the caster wheels 4 with respect to the loading platform longitudinal center line Oy. As a result, since the share of the load applied to the caster wheel 4 is reduced, the frictional resistance of the caster wheel 4 that is steered so as to face the traveling direction is suppressed, the power required for starting is reduced, and the heavy load is smoothed. It becomes possible to transport to.

  As shown in FIG. 3B, roller wheels 6 are provided side by side with the drive wheels 5 in the left-right direction. The left and right roller wheels 6 are provided side by side inside the left and right drive wheels 5.

  The left and right drive wheels 5 are arranged so as to be equidistant in the left-right direction from a center line Ox extending in the front-rear direction of the loading platform 3.

  The left and right roller wheels 6 are arranged so as to be equidistant in the left-right direction from the center line Ox extending in the front-rear direction of the loading platform 3.

  3A and 3B, a drive wheel shaft installation surface S extending in the left-right direction is set, and the wheel rotation shafts of the left and right drive wheels 5 and the left and right roller wheels 6 (on the drive wheel shaft installation surface S ( Wheel center axes) are arranged respectively. The drive wheel shaft installation surface S is a vertical surface that is orthogonal to the left-right direction center line Ox of the loading platform and extends in parallel with the center line Oy that extends in the left-right direction of the loading platform 3.

  The drive wheel shaft installation surface S is arranged behind the center line Oy. The wheel rotation axis O4 of the caster wheel 4 is disposed in front of the center line Oy in the longitudinal direction of the loading platform.

  The drive wheel 5 includes a wheel 5c that is rotatably supported via a wheel shaft 5b, and a rubber tire 5a that is attached to the outer periphery of the wheel 5c, and the tire 5a is brought into rolling contact with the road surface. The inside of the tire 5a is filled with air or a rubber material, and a contact portion with respect to the road surface is elastically deformed into a flat shape by a load applied thereto, and a load of, for example, 50 kg or less is supported.

  The roller wheel 6 includes a hard resin roller 6a, and the annular roller 6a is brought into rolling contact with the road surface. In the roller wheel 6, the contact portion with respect to the road surface of the roller 6a is not greatly elastically deformed, and can support a load of 200 to 900 kg, for example.

  The roller wheel 6 has a higher contact portion with respect to the road surface than the drive wheel 5 and has a large load resistance.

  4A is a front view of the electric assist cart 1 as viewed from the front, and FIG. 4B is a front view of the electric assist cart 1 as viewed from the rear.

  The suspension device 20 is provided with left and right subframes 21 that respectively support the left and right drive wheels 5 and the roller wheels 6.

  Both end portions of the wheel shaft 5 b of the drive wheel 5 are supported by the subframe 21.

  The roller wheel 6 has an outer diameter (wheel diameter) smaller than that of the drive wheel 5, and both end portions of the wheel shaft (not shown) are supported by the bracket 7, and the bracket 7 is fastened to the lower portion of the subframe 21. . As a result, the roller wheel 6 can be disposed close to the drive wheel 5.

  The suspension device 20 includes a suspension arm 22 that is provided on each side of the traveling frame 2 so that the left and right subframes 21 can be moved up and down, and a spring that is provided between the traveling frame 2 and the left and right subframes 21. And a damper 23.

  Each suspension arm 22 is connected at both ends to the traveling frame 2 and the left and right subframes 21 so as to be rotatable around a horizontal axis, and supports the subframe 21 so that the subframe 21 can be translated relative to the traveling frame 2. Configure the mechanism.

  Based on the above configuration, even if the sub frame 21 moves up and down with respect to the traveling frame 2, the posture of the sub frame 21 does not change, and the positional relationship (alignment) between the drive wheels 5 and the roller wheels 6 is kept constant. Thereby, even if the sub-frame 21 moves up and down, one of the drive wheel 5 and the roller wheel 6 is suppressed from floating from the road surface.

  The suspension device 20 is not limited to this, and may have another structure as long as the posture of the subframe 21 with respect to the traveling frame 2 is maintained.

  The spring damper 23 includes a coiled spring 23a and a suspension damper 23b, and expands and contracts as the subframe 21 moves up and down.

  The spring 23a supports the load received by the subframe 21 by the spring force, and expands and contracts as the subframe 21 moves up and down.

  As the suspension damper 23b expands and contracts, hydraulic oil filled therein flows through a damping mechanism (not shown), and generates a damping force that suppresses vibration of the subframe 21 due to road surface irregularities. Thereby, the vibration of the sub-frame 21 is suppressed from being transmitted to the traveling frame 2.

  FIG. 5 is a circuit diagram showing a configuration of a motor driving device 61 that drives the electric motors 51 and 52. The motor drive device 61 includes a plug 62, a charger 70, a battery 75, a controller 76, and a switch 80.

  When the mating plug 63 is inserted into the plug 62, the plug 62 is connected to the power source 79 via a cord (electric wire) 78 extending from the mating plug 63. The plug 62 is a magnet jack type, and the mating plug 63 is inserted by a magnetic force.

  The charger 70 converts an alternating current supplied via the input circuit 64 into a direct current, and charges the battery 75 via the charging circuit 65. A pair of input circuits 64 that connect the plug 62 and the charger 70 are provided, and a pair of charging circuits 65 that connect the charger 70 and the battery 75 are provided.

  The battery 75 and the controller 76 are connected via a pair of output circuits 66. The controller 76 and the left and right electric motors 51 and 52 are connected via a pair of output circuits 53 and 54. The direct current stored in the battery 75 is supplied to the left and right electric motors 51 and 52 via the controller 76.

  As described above, the controller 76 supplies electric power to the electric motors 51 and 52 according to the operation force by which the operator pushes the operation handle 8 to control the drive of the left and right drive wheels 5.

  The switch 80 includes a relay coil 81 that is energized as the counterpart plug 63 is inserted into the plug 62 and connected to the power source 79, and four relay contacts 82 that are opened and closed by electromagnetic force generated in the relay coil 81. ~ 85.

  The relay coil 81 is interposed in a branch circuit 68 that branches from the input circuit 64, and is energized through the input circuit 64 and the branch circuit 68 as the mating plug 63 is inserted into the plug 62.

  The relay contacts 83 and 85 are interposed in the pair of charging circuits 65, respectively. The relay contacts 83 and 85 are normally open types that are opened when the relay coil 81 is not energized.

  The relay contacts 82 and 84 are interposed in the pair of output circuits 66, respectively. The relay contacts 82 and 84 are normally closed types that close when the relay coil 81 is not energized.

  Next, the operation of the motor drive device 61 will be described.

  As shown in FIG. 5, when the electric assist cart 1 travels, the switch 80 has relay contacts 82 and 84 closed, and the electric power stored in the battery 75 is supplied to the left and right electric motors 51 via the controller 76. , 52. At this time, the relay contacts 83 and 85 are opened and the charging circuit 65 is shut off, so that the power of the battery 75 is prevented from being supplied to the charger 70.

  When the electric assist cart 1 is charged, the relay coil 81 is energized as the mating plug 63 is inserted into the plug 62 and connected to the power source 79, so that the relay is caused by electromagnetic force generated in the relay coil 81. The contacts 83 and 85 are closed, and the direct current output from the charger 70 is charged to the battery 75 via the charging circuit 65. At this time, the relay contacts 82 and 84 are opened and the output circuit 66 is cut off, so that the direct current output from the charger 70 is avoided from being supplied to the left and right electric motors 51 and 52, and is electrically driven during charging. The assist cart 1 can be prevented from starting wrongly.

  As described above, in this embodiment, the electric assist cart 1 is assisted by the electric motors 51 and 52, and is supplied via the plug 62 connected to the external power supply 79 and the plug 62. A charger 70 that converts an alternating current into a direct current and outputs it, a charging circuit 65 that directs the direct current output from the charger 70 to the battery 75, and electric motors 51 and 52 that store electric power stored in the battery 75. And an output circuit 66 that outputs the output circuit 66 and a switch 80 that shuts off the output circuit 66 during charging.

  Based on the above configuration, when the AC current is supplied to the charger 70 and the DC current output from the charger 70 is charged into the battery 75, the output circuit 66 is cut off, so the DC current output from the charger 70 is Is supplied to the left and right electric motors 51 and 52, but charging can be performed safely.

  In this embodiment, the switch 80 includes a relay coil 81 that is energized as the plug 62 is connected to the power source 79, and a normally closed type that is closed when the relay coil 81 is not energized and opened when the relay coil 81 is energized. The relay contacts 82 and 84 are provided. The normally closed relay contacts 82 and 84 are interposed in the output circuit 66, and are opened during charging to shut off the output circuit 66.

  Based on the above configuration, since the output circuit 66 is shut off as the plug 62 is connected to the power source 79, charging can be performed safely.

  In the present embodiment, the switching device 80 includes normally-open relay contacts 83 and 85 that are opened when the relay coil 81 is not energized and closed when the relay coil 81 is energized. The battery is opened when not charged and the charging circuit 65 is shut off.

  Based on the above configuration, the battery 75 is prevented from flowing back into the charger 70.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

1 Electric assist cart
51, 52 Electric motor 53 Output circuit 61 Motor drive device 62 Plug 64 Input circuit 65 Charging circuit 66 Output circuit 70 Charger 75 Battery 76 Controller 79 Power supply 80 Switch 81 Relay coil 82, 84 Normally closed relay contact 83, 85 Always Open relay contact

Claims (3)

An electric assist cart whose power is assisted by an electric motor,
A plug connected to an external power supply;
A charger that converts the alternating current supplied through the plug into a direct current and outputs the direct current; and
A charging circuit for guiding the direct current output from the charger to the battery;
An output circuit that outputs the electric power stored in the battery to the electric motor;
An electric assist cart comprising: a switching device that shuts off the output circuit during charging. The switch is
A relay coil that is energized as the plug is connected to the power source;
A normally closed relay contact that closes when the relay coil is not energized and opens when energized,
2. The electric assist cart according to claim 1, wherein the normally closed relay contact is interposed in the output circuit, and is configured to open during charging to interrupt the output circuit. The switch is
A normally open relay contact that opens when the relay coil is not energized and closes when energized;
The electric assist cart according to claim 2, wherein the normally open relay contact is interposed in the charging circuit and is configured to be opened when the battery is not charged to interrupt the charging circuit.

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