JP5719606B2 - Electric assist cart and electric assist unit for cart - Google Patents

Description

  The present invention relates to an electric assist cart whose driving force is assisted by an electric motor, and an electric assist unit of the cart.

  Generally, when a heavy load is placed on a cart used in a factory or the like, an operator needs to push the cart with a large force at the start of transportation, which is a heavy labor.

  As a countermeasure against this, Patent Document 1 proposes an electric assist hand cart that detects the force of an operator pushing the cart and is provided with auxiliary power corresponding to human power by an electric motor. In this electrically assisted hand cart, the pushing force of the worker at the time of forward movement and backward movement is assisted according to the operation of the hand frame by the worker.

JP 2006-290319 A

  However, since the electric assist hand cart described in Patent Document 1 performs only forward and backward assist, there is a possibility that a sense of incongruity may occur with respect to the operator's operation when turning.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide an electric assist cart in which a driving force is assisted without a sense of incongruity according to an operation of an operator.

The present invention includes a vehicle body frame on which a load can be placed via a loading platform, an operation unit that can be pressed by an operator and capable of inputting driving force from two left and right sides of the vehicle body frame, and a lower portion of the vehicle body frame. An electric assist cart provided with an electric assist unit according to a pressing operation of the operation unit, wherein the electric assist unit includes a flat plate portion and the flat plate attached to a lower surface of the vehicle body frame. a body portion that having a a protruding portion formed to protrude toward between the pair of driving wheels from parts, rotatably mounted around the axle at the bottom of said plate, at intervals in the left-right a pair of drive wheels provided, attached to a lower surface of said plate while being connected to the operating unit, Nica left of the vehicle body frame by the operation portion is pressed A pair of torque detection unit that detects a driving torque applied to each, are accommodated in the projecting portion, the assist force applied to the drive wheel of each in accordance with the detected driving torque by the torque detecting unit A controller for calculating, and a pair of electric motors attached to the projecting portion and applying an assist force calculated by the controller to each of the drive wheels.

  In the present invention, when the operator presses the operating portion, the driving torque acting on the left and right portions of the body frame is detected, and the assisting force is applied to the left and right driving wheels according to the detected driving torque. Therefore, for example, when the left and right driving force input from the operation unit is different and the vehicle turns, the assist force applied to the left and right driving wheels can be made different according to the input driving force. . Therefore, the driving force can be assisted without a sense of incongruity according to the operation of the operator.

1 is a perspective view of an electric assist cart according to an embodiment of the present invention. It is a side view in FIG. It is a bottom view in FIG. It is AA sectional drawing in FIG.

  Hereinafter, an electric assist cart 100 according to an embodiment of the present invention will be described with reference to the drawings.

  First, the configuration of the electric assist cart 100 will be described with reference to FIGS. 1 to 4.

  The electric assist cart 100 is used for transporting heavy objects, for example, in a factory. The electric assist cart 100 travels with the driving force applied by the operator being applied with an assist force due to the rotation of the electric motor 15 described later.

  The electric assist cart 100 includes a body frame 1 having a loading platform 3 formed on an upper surface, an operation handle 5 as an operation unit capable of inputting driving force from two left and right portions of the body frame 1, and a pair attached to the body frame 1. And the electric assist unit 50 for applying the assist force of the electric motor 15 to the drive force applied by the operator.

  The body frame 1 is formed in a rectangular flat plate shape, and the upper surface thereof constitutes the loading platform 3. As the vehicle body frame 1, a frame of a normal handcart can be used as it is. The vehicle body frame 1 has a pair of elongated holes 1d that are long in the front-rear direction and through which the operation handle 5 is inserted.

  The elongated hole 1d is formed longer in the front-rear direction as the operation handle 5 rotates in the front-rear direction around the base end. The long hole 1d is formed by performing additional machining on the frame of a normal manual carriage.

  The long hole 1d may not have a long hole shape as long as it is a through hole having a shape that allows the operation handle 5 to rotate. Instead of forming the long hole 1d, the diameter of the operation handle 5 may be changed to a smaller one so that the operation handle 5 can be rotated. Alternatively, the operation handle 5 may be formed in an L shape without forming the elongated hole 1 d so that the operation handle 5 stands up through the rear of the vehicle body frame 1.

  The operation handle 5 is an inverted U-shaped handle that is pressed by an operator. Both left and right ends of the operation handle 5 are connected to the vehicle body frame 1 via a torque sensor 6 described later. As a result, the driving force input by the operator operating the operation handle 5 is transmitted to the vehicle body frame 1. The operation handle 5 is provided so as to be rotatable in the front-rear direction via the torque sensor 6 by an operator's pressing operation.

  The universal wheel 12 is a small wheel that always faces in the traveling direction when traveling. The universal wheel 12 is turned by the frictional resistance with the road surface and is steered so as to face the traveling direction. The universal wheel 12 constitutes a front wheel of the electric assist cart 100.

  The electric assist unit 50 is operated by pressing the main body 20 attached to the lower surface of the body frame 1, a pair of drive wheels 11 that are provided on the left and right sides of the body frame 1 and constitute rear wheels, and the operation handle 5. Thus, a torque sensor 6 as a pair of torque detectors for detecting drive torque acting on each of the left and right portions of the vehicle body frame 1 and each drive wheel 11 according to the drive torque detected by the torque sensor 6 A controller 30 that calculates the assist force to be applied and a pair of electric motors 15 that apply the assist force calculated by the controller 30 to each drive wheel 11 are provided.

  The electric assist unit 50 is integrally formed and fixed to the lower surface of the vehicle body frame 1. As a result, the cart can be electrically assisted only by removing the rear wheel of a normal manual cart and attaching the electric assist unit 50. Therefore, since the existing manual cart can be easily electrically assisted, the cost can be suppressed.

  The main body 20 includes a flat plate portion 21 fixed to the lower surface of the vehicle body frame 1 and a protruding portion 22 formed to protrude from the flat plate portion 21 between the pair of drive wheels 11.

  The flat plate portion 21 is a substantially rectangular flat plate that is fixed in a state where the upper surface is in contact with the lower surface of the vehicle body frame 1. The left and right torque sensors 6 are fixed to the lower surface of the flat plate portion 21 via a pair of brackets 21a.

  Like the body frame 1, a pair of elongated holes 21 d that are formed in the front-rear direction and through which the operation handle 5 is inserted are continuously formed in the flat plate portion 21 in the same shape as the elongated holes 1 d of the body frame 1.

  The protruding portion 22 is a box-like case that protrudes from the center of the flat plate portion 21 along the front-rear direction of the body frame 1. A controller 30 is housed inside the protrusion 22. A pair of electric motors 15 are fixed to the left and right surfaces of the protrusion 22, and the left and right drive wheels 11 are attached via the electric motor 15. Since the electric motor 15 is fixed so as not to rotate with respect to the protruding portion 22, the electric motor 15 is prevented from rotating by its driving force, and the driving force can be reliably transmitted to the driving wheels 11.

  The drive wheel 11 is a small wheel provided in the front-rear direction of the body frame 1 so as not to be steered. A pair of drive wheels 11 are provided in the vicinity of the rear end of the body frame 1. The drive wheel 11 is provided behind the pair of free wheels 12 and constitutes a rear wheel of the electric assist cart 100.

  The drive wheels 11 are respectively fixed to the lower part of the flat plate part 21 in the main body part 20 via a pair of brackets 21b. Thereby, the weight of the vehicle body frame 1 and the weight of the load loaded on the loading platform 3 are supported by the drive wheels 11 via the bracket 21b.

  Thus, since the vehicle body frame 1 is supported by the drive wheels 11 via the brackets 21b, the weight of the load on the vehicle body frame 1 and the loading platform 3 is not transmitted to the electric motor 15.

  The electric motor 15 is electrically connected to the controller 30 and rotates according to an electrical signal input from the controller 30. The electric motor 15 is disposed such that its rotating shaft faces the traveling direction of the drive wheel 11. The electric motor 15 includes a transmission 16 that decelerates the rotation and converts the rotation direction to transmit to the drive wheels 11.

  As shown in FIG. 4, the transmission 16 includes a worm 16 a that rotates by the rotation of the electric motor 15, and a worm wheel 16 b that meshes with the worm 16 a and is fixed to the drive wheel 11. The transmission 16 decelerates the rotation of the electric motor 15 and converts the rotation direction to vertical and outputs the result.

  Here, when the electric motor 15 is provided in series so that the rotation shaft thereof faces the left-right direction of the vehicle body frame 1 and disposed between the pair of drive wheels 11, if the electric motor 15 is long, The distance between the drive wheels 11 becomes large, and it is difficult to reduce the size of the electric assist cart 100.

  On the other hand, in the electric assist cart 100, the rotation shaft of the electric motor 15 is disposed so as to face the traveling direction of the driving wheel 11, so that the electric assist cart 100 is not connected to the pair of driving wheels 11 regardless of the entire length of the electric motor 15. The distance can be set. Therefore, the electric assist cart 100 can be reduced in size.

  The torque sensor 6 is electrically connected to the controller 30 and outputs an electrical signal corresponding to the detected driving torque to the controller 30. The torque sensor 6 is connected to the operation handle 5 and the vehicle body frame 1 and is twisted by the driving force input from the operation unit and transmits the driving force to the vehicle body frame 1, and the torsion bar is twisted. And a potentiometer (not shown) that outputs an electrical signal corresponding to the torsion bar, and detects the drive torque based on the torsion bar twist.

  Specifically, the torque sensor 6 includes an input shaft (not shown) provided integrally with the operation handle 5 and an output shaft (not shown) fixed to the vehicle body frame 1. In the torque sensor 6, when the input shaft rotates relative to the output shaft, the rotation is converted into a linear motion by a helical spline mechanism (not shown), and a cylindrical sleeve (not shown) provided on the outer periphery of the torsion bar is a shaft. Displace in the direction. A potentiometer lever is engaged with the outer periphery of the sleeve.

  The torque sensor 6 changes the magnitude of the voltage signal output from the potentiometer when the lever of the potentiometer is moved in accordance with the displacement of the sleeve. Thereby, the torque sensor 6 can output a voltage signal corresponding to the twist of the torsion bar, that is, a voltage signal corresponding to the magnitude of the driving torque.

  The controller 30 is mounted on the protrusion 22 in the main body 20 together with the power supply device and other electronic devices. The controller 30 controls the electric assist cart 100 and includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and an I / O interface (input / output interface). It consists of a microcomputer. The RAM stores data in the processing of the CPU, the ROM stores a control program of the CPU in advance, and the I / O interface is used for input / output of information with the connected device. Control of the electric assist cart 100 is realized by operating a CPU, a RAM, and the like according to a program stored in the ROM.

  The controller 30 performs control to cause the left and right electric motors 15 to generate assist force corresponding to the driving torque detected by the left and right torque sensors 6 to move the electric assist cart 100 forward or backward, as well as go straight, turn, bend Assist force to be applied.

  Hereinafter, the operation of the electric assist cart 100 will be described.

  First, a case where the electric assist cart 100 is moved forward or backward straight will be described.

  When the operator pushes the operation handle 5 with both hands in parallel, the electric assist cart 100 moves straight forward. In this case, the driving force input to the vehicle body frame 1 when the operation handle 5 is pressed is substantially the same at the left and right ends of the operation handle 5. Therefore, the drive torques detected by the left and right torque sensors 6 are substantially the same.

  When the left and right torque sensors 6 detect the same drive torque, the controller 30 commands the left and right electric motors 15 to apply the same assist force to the left and right drive wheels 11. Thereby, the same assist force is applied to the left and right drive wheels 11.

  Therefore, the electric assist cart 100 moves straight forward with the assist force of the electric motor 15 applied to the driving force applied by the operator.

  When the electric assist cart 100 is moved straight backward, the direction in which the operation handle 5 is pushed is reversed, and the rotation direction of the electric motor 15 is reversed, and the other actions are the same as in the case of moving straight forward. is there.

  Next, the case where the electric assist cart 100 is turned will be described.

  When the left and right forces pushing the operation handle 5 are made different by the operator, the electric assist cart 100 turns to the left or right. At this time, the assist force applied to the left and right drive wheels 11 differs between the left and right electric motors 15.

  Specifically, for example, when the electric assist cart 100 is turned leftward, the force with which the operator pushes the operation handle 5 with the right hand is larger than the force with which the operation handle 5 is pushed with the left hand. Therefore, the drive torque detected by the right torque sensor 6 is larger than the drive torque detected by the left torque sensor 6.

  Thereby, the controller 30 commands the assist force applied from the right electric motor 15 to the drive wheels 11 to be larger than the assist force applied from the left electric motor 15 to the drive wheels 11. As a result, the assist force applied to the right drive wheel 11 is greater than the assist force applied to the left drive wheel 11.

  Since the left and right torque sensors 6 can detect the drive torque steplessly, the magnitude of the assist force can be controlled according to the force with which the operator presses the operation handle 5.

  As described above, when the left and right driving force input from the operation handle 5 differs by the operator and the electric assist cart 100 turns, it is applied to the left and right driving wheels 11 according to the input driving force. The assist force to be made can be made different. Therefore, the driving force can be assisted without a sense of incongruity according to the operation of the operator.

  Thus, the electric assist cart 100 can assist the operator's operation not only when moving forward and backward, but also when turning, only by operating the operation handle 5. Therefore, the operator can intuitively operate the electric assist cart 100 with the same feeling as an ordinary manual cart. Therefore, the operator does not need to perform special training in order to operate the electric assist cart 100. In addition, even an operator who is not familiar with the operation can easily operate the electric assist cart 100.

  Thus, since the electric assist cart 100 can operate faithfully to the operator's intention, it does not perform an operation unintended by the operator and is excellent in safety. Moreover, since the electric assist cart 100 consumes electric power only when the assist force by the electric motor 15 is required, the electric assist cart 100 is excellent in energy saving performance.

  According to the above embodiment, the following effects are obtained.

  When the operation handle 5 is pressed by the operator, the drive torque acting on the left and right portions of the vehicle body frame 1 is detected by the torque sensor 6, and assist force is applied to the left and right drive wheels 11 according to the detected drive torque. To do. Therefore, for example, when the left and right driving forces input from the operation handle 5 are different and the vehicle turns, the assist force applied to the left and right driving wheels 11 according to the driving force input by the operator is obtained. Can be different. Therefore, the driving force can be assisted without a sense of incongruity according to the operation of the operator.

  In addition, by providing the electric assist unit 50 that is integrally formed and fixed to the lower surface of the vehicle body frame 1, the electric assist of the cart can be achieved simply by removing the rear wheel of a normal manual cart and attaching the electric assist unit 50. It becomes possible. Therefore, since the existing manual cart can be easily electrically assisted, the cost can be suppressed.

  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.

  The electric assist cart according to the present invention can be used as a cart for carrying luggage.

100 Electric Assist Cart 50 Electric Assist Unit 1 Body Frame 1d Slot 5 Operation Handle (Operation Unit)
6 Torque sensor (torque detector)
DESCRIPTION OF SYMBOLS 11 Drive wheel 12 Swivel wheel 15 Electric motor 16 Transmission 20 Main body part 21 Flat plate part 22 Projection part 30 Controller

Claims (6)

A body frame on which luggage can be placed via a loading platform;
An operation unit that is pressed by an operator and capable of inputting a driving force from two places on the left and right of the body frame;
An electric assist cart provided at a lower portion of the vehicle body frame, and an electric assist unit that applies an assist force in response to a pressing operation of the operation unit,
The electric assist unit is
A body portion that having a a protruding portion formed to protrude toward between the pair of driving wheels from said plate a flat plate portion attached to the underside of the body frame,
A pair of drive wheels attached to the lower portion of the flat plate portion so as to be rotatable around an axle, and provided with a left and right spacing;
A pair of torque detectors connected to the operation unit and attached to the lower surface of the flat plate part, and detecting a driving torque acting on each of the two left and right parts of the vehicle body frame when the operation unit is pressed; ,
A controller for calculating an assist force to be applied to each of the driving wheels according to the driving torque that is housed in the protruding portion and detected by the torque detecting unit;
An electric assist cart comprising: a pair of electric motors attached to the protrusions and applying an assist force calculated by the controller to each of the drive wheels. Before Symbol pair of drive wheels, an electric assist cart according to claim 1, characterized in that it is supported by the projecting portion through the pair of electric motors. The operation unit is provided so as to be rotatable in the front-rear direction by an operator's pressing operation,
3. The electric assist cart according to claim 1, wherein the vehicle body frame has through holes formed at intervals at which the operation portion is rotatable. The electric motor is disposed such that its rotating shaft faces the traveling direction of the drive wheel,
The electric assist cart according to any one of claims 1 to 3, further comprising a transmission that decelerates the rotation of the electric motor and converts a rotation direction to transmit the rotation to the drive wheels. The drive wheel is provided so as not to be steered,
The electric assist cart according to any one of claims 1 to 4, further comprising a pair of universal wheels mounted on the vehicle body frame and provided in front of the drive wheels. Used in a carriage having a vehicle body frame on which a load can be placed via a loading platform, and an operation unit that can be pressed by an operator and can input a driving force from two places on the left and right of the vehicle body frame. An electric assist unit for applying an assist force according to an operation,
A body portion that having a a protruding portion formed to protrude toward between the pair of driving wheels from said plate a flat plate portion attached to the underside of the body frame,
A pair of drive wheels attached to the lower portion of the flat plate portion so as to be rotatable around an axle, and provided with a left and right spacing;
A pair of torque detectors connected to the operation unit and attached to the lower surface of the flat plate part, and detecting a driving torque acting on each of the two left and right parts of the vehicle body frame when the operation unit is pressed; ,
A controller for calculating an assist force to be applied to each of the driving wheels according to the driving torque that is housed in the protruding portion and detected by the torque detecting unit;
An electric assist unit for a carriage, comprising: a pair of electric motors attached to the protrusions and applying an assist force calculated by the controller to each of the drive wheels.

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