JP2012171374A - Electric power-assisted truck - Google Patents

Abstract

An electric assist cart is provided at low cost.
An electric assist cart 100 capable of traveling with an assist force applied to a driving force applied by an operator, the vehicle body frame 1 being capable of placing a load via a cargo bed 3, and the vehicle body frame 1. A pair of drive wheels 11 provided at intervals on the left and right, an operation handle 5 that can be pressed by an operator and input a driving force from two places on the left and right of the body frame 1 and can be tilted back and forth by the pressing operation; A pair of contact detection units 40 that are respectively attached to two left and right positions of the vehicle body frame 1 so as to come into contact with each other when the operation handle 5 is tilted forward and backward, and a contact detection unit 40 is provided on the operation handle 5. When contact is detected, a pair of electric motors 15 are provided that increase the output to a maximum value over a predetermined time and apply assist force to each drive wheel 11.
[Selection] Figure 1

Description

  The present invention relates to an electric assist cart whose driving force is assisted by an electric motor.

  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, in the electrically assisted hand cart described in Patent Document 1, the handle operation is detected using a magnet that generates a magnetic force and a Hall element that detects the magnetic force of the magnet, so an expensive sensor including the Hall element is used. There is a need.

  The present invention has been made in view of the above problems, and an object thereof is to provide an electric assist cart at a low cost.

  The present invention relates to an electric assist cart capable of traveling with an assist force applied to a driving force applied by an operator, and a vehicle body frame on which a load can be placed via the load platform, and a space between the vehicle body frame and the left and right A pair of drive wheels provided with a gap between them, an operation unit that is pressed by an operator and capable of inputting driving force from two places on the left and right of the body frame, and that can be tilted back and forth by the pressing operation, and the operation unit A pair of contact detectors that are attached to the left and right parts of the body frame so as to come into contact with each other when the vehicle tilts back and forth, and detects the contact of the operation unit, and the contact detection unit detects the contact of the operation unit In this case, the output is increased to a maximum value over a predetermined time, and a pair of electric motors that apply assist force to each of the drive wheels is provided.

  In the present invention, when the operation unit is pressed and the contact detection unit detects contact of the operation unit, the output of the electric motor is increased to the maximum value over a predetermined time to apply assist force to the drive wheels. . In this way, even if the size of the pressing operation by the operator is not detected, when contact is detected by the contact detection unit, the output of the electric motor is gradually increased over a predetermined time, It is possible to give an assist force that does not feel uncomfortable for the operator. Therefore, since it is not necessary to use an expensive sensor to detect the magnitude of the pressing operation by the operator, the electric assist cart can be provided at a low cost.

It is a side view of the electric assist cart concerning an embodiment of the invention. FIG. 2 is an enlarged view of the vicinity of a contact detection unit in FIG. 1. It is an expanded sectional view of the electric motor vicinity in FIG. It is a graph explaining the effect | action of an electrically assisted trolley | bogie.

  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 vehicle 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 sides of the vehicle body frame 1, an operation handle 5 and a vehicle body frame 1. A torsion bar 7 that connects the two, a pair of contact detectors 40 that detect the contact of the operation handle 5, an electric assist unit 50 for applying an assisting force of the electric motor 15 to a driving force applied by an operator, And a pair of free wheels 12 attached to the body frame 1.

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

  As will be described later, the elongated hole 1a is formed longer in the front-rear direction as the operation handle 5 is tilted in the front-rear direction around the base end 5a. The long hole 1a is formed by performing additional machining on the frame of a normal manual carriage.

  The long hole 1a may not be a long hole shape as long as it is a through hole having a shape that allows the operation handle 5 to be inclined. Instead of forming the long hole 1a, the diameter of the operation handle 5 may be changed to a smaller one so that the operation handle 5 can be rotated. Further, the operation handle 5 may be formed in an L shape without forming the elongated hole 1a, and the operation handle 5 may be erected 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 torsion bars 7.

  The torsion bar 7 is provided such that its central axis faces the left-right direction of the body frame 1. One end of the torsion bar 7 is connected to the base end 5 a of the operation handle 5, and the other end is connected to the vehicle body frame 1. Thus, when the operation handle 5 is pressed by the operator, the torsion bar 7 is twisted, and the driving force input by the operator operating the operation handle 5 is applied to the vehicle body frame via the torsion bar 7. 1 is transmitted. At this time, as the torsion bar 7 is twisted, the operation handle 5 can be tilted in the front-rear direction around the base end 5a.

  Rather than connecting the operation handle 5 and the vehicle body frame 1 by the torsion bar 7, the operation handle 5 is provided so as to be rotatable with respect to the vehicle body frame 1 so that the operation handle 5 is positioned at the neutral position. A biasing member such as a coil spring for biasing from the front-rear direction may be provided.

  As shown in FIG. 2, the contact detectors 40 are respectively attached to the left and right positions of the vehicle body frame 1 so as to come into contact when the operation handle 5 is inclined in the front-rear direction. The contact detection unit 40 detects a tilt in the front-rear direction of the operation handle 5 that occurs as the torsion bar 7 is twisted.

  The contact detection unit 40 includes a front contact switch 41 and a rear contact switch 42 that are respectively provided before and after the operation handle 5, and a bracket 43 that houses the front contact switch 41 and the rear contact switch 42.

  The bracket 43 is formed in a substantially U shape so as to cover the base end 5 a of the operation handle 5. The bracket 43 is fixed so as to protrude downward from the lower surface of the vehicle body frame 1. A front contact switch 41 positioned in front of the operation handle 5 and a rear contact switch 42 positioned behind the operation handle 5 are attached to the inner periphery of the bracket 43.

  The front contact switch 41 includes a fixed portion 41a attached to the inner periphery of the bracket 43, and an arm portion 41b that can rotate with respect to the fixed portion 41a. The front contact switch 41 is pressed by the inclination of the operation handle 5 when the operation handle 5 is pressed forward by the operator, that is, when the operator tries to move the electric assist cart 100 forward. By this pressing, the arm portion 41b rotates toward the fixed portion 41a, and the front contact switch 41 is turned on. That is, the front contact switch 41 detects the contact of the operation handle 5 and outputs a signal when the forward tilt of the arm portion 41b becomes equal to or greater than a predetermined displacement.

  Similarly, the rear contact switch 42 includes a fixed portion 42a attached to the inner periphery of the bracket 43, and an arm portion 42b that can rotate with respect to the fixed portion 42a. The rear contact switch 42 is used when the operator pushes the operation handle 5 backward, that is, when the operator attempts to decelerate or stop the electric assist cart 100 or to move the electric assist cart 100 backward. Sometimes it is pressed by the inclination of the operation handle 5. By this pressing, the arm part 42b rotates toward the fixed part 42a, and the rear contact switch 42 is turned on. That is, the rear contact switch 42 detects the contact of the operation handle 5 and outputs a signal when the rearward inclination of the arm portion 42b becomes equal to or greater than a predetermined displacement.

  As shown in FIG. 1, the electric assist unit 50 includes a main body 20 that is 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 that constitute rear wheels, A controller 30 that calculates the assist force applied to each drive wheel 11 in accordance with the contact of the operation handle 5 detected by the contact detection unit 40, and the assist force calculated by the controller 30 is applied to each drive wheel 11. A pair of electric motors 15.

  The electric assist unit 50 is integrally formed and fixed to the lower surface of the vehicle body frame 1. As a result, the carriage can be electrically assisted only by removing the front wheel of a normal manual carriage 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 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 front end of the body frame 1. The drive wheel 11 constitutes a front 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 21a. Thereby, the weight of the vehicle body frame 1 and the weight of the load mounted on the loading platform 3 are supported by the drive wheels 11 through the bracket 21a.

  Thus, the body frame 1 is supported by the drive wheels 11 via the bracket 21 a, so that the weight of the load on the body frame 1 and the loading platform 3 is not transmitted to the electric motor 15.

  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 rotation and converts the rotation direction to transmit to the drive wheels.

  As shown in FIG. 3, 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 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 controls the output of the electric motor 15 based on the detection of the contact of the operation handle 5 by the contact detection unit 40, and gives the assist force to move the electric assist cart 100 forward or backward and to move straight, turn, or bend. To do.

  When the contact detection unit 40 detects the contact of the operation handle 5, the controller 30 adjusts the duty ratio of the electric motor 15 by PWM control (Pulse Width Modulation: pulse width modulation control), and the output of the electric motor 15 is Increase proportionally to the maximum value over a given time.

  Here, the PWM control in the controller 30 will be described in detail with reference to FIG. In FIG. 4, the horizontal axis indicates the change in time, and the vertical axis indicates the input of the signal detected by the contact detection unit 40 and the magnitude of the output to the electric motor 15.

  A time T0 shown in FIG. 4 is a state in which the operator does not push the operation handle 5. At this time, since the contact detection unit 40 does not detect the contact of the operation handle 5, the output of the electric motor 15 is zero, and no assist force is applied to the drive wheels 11.

  At time T1, the worker starts to push the operation handle 5. At this time, the operation handle 5 comes into contact with the contact detection unit 40 due to the twist of the torsion bar 7, and the contact detection unit 40 is switched on. When the contact detection unit 40 is switched on, the controller 30 proportionally increases the duty ratio of the electric motor 15 by PWM control. As a result, the assist force applied to the drive wheels 11 gradually increases.

  At time T2, the operation handle 5 is continuously pressed from T1 by the operator. At time T2, a predetermined time has elapsed from T1, and the output of the electric motor 15 has increased to the maximum value. After the output from the electric motor 15 rises to the maximum value, the assist force is applied to the drive wheels 11 while maintaining the output as it is.

  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 is provided behind the pair of drive wheels 11 and constitutes a rear wheel of the electric assist cart 100.

  As described above, in the electric assist cart 100, the front wheel is the driving wheel 11 and the rear wheel is the universal wheel 12, but the front wheel may be the universal wheel 12 and the rear wheel may be the driving wheel 11. When the front wheel is the drive wheel 11 and the rear wheel is the free wheel 12, the free wheel 12 steered at the time of turning is close to the worker, so that the worker can easily control the turning. Therefore, compared with the case where the front wheel is the universal wheel 12 and the rear wheel is the drive wheel 11, the operability during turning is improved.

  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 both the left and right ends of the operation handle 5, and the left and right front contact switches 41 are provided by the operator. Is switched on at substantially the same timing by the pressing operation.

  When the left and right front contact switches 41 are turned on at the same timing, the controller 30 adjusts the duty ratio of the left and right electric motors 15 by PWM control to maximize the outputs of the left and right electric motors 15 in the same way. Command to increase to value. Thereby, the same assist force is always 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.

  Here, when the electric assist cart 100 is moved straight forward, the timing at which the operator pushes the operation handle 5 with the left and right hands is shifted, and the timing at which the assist force applied from the left and right electric motors 15 is increased may be shifted. is there.

  For example, when the electric assist cart 100 moves slightly to the left rather than straight ahead, the operator releases the right hand from the operation handle 5 and presses it with only the left hand, so that the electric assist cart 100 returns to a straight state. Then, the operation handle 5 may be pushed again with both hands. Since this operation is the same as the operation of the operator in a normal manual carriage, the operator can perform the operation intuitively.

  In this way, by finely pressing the operating handle 5 with the left and right hands and turning the front contact switch 41 intermittently on, the assist force is finely adjusted, and the attitude of the electric assist cart 100 is adjusted. Is possible.

  On the other hand, when the electric assist cart 100 is retracted straight, the rear contact switch 42 is switched on instead of the front contact switch 41 because the direction in which the operation handle 5 is tilted is opposite to the forward direction. The other operations are the same as in the case where the electric motor 15 is rotated in the reverse direction, and the other actions are the same as in the case of moving straight forward.

  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 turning the electric assist cart 100 in the left direction, the operator pushes the operation handle 5 with the right hand and does not push the operation handle 5 with the left hand or pulls it backward.

  When the operator pushes the operation handle 5 with the right hand and does not push the operation handle 5 with the left hand, only the right front contact switch 41 is turned on. As a result, the controller 30 commands the assisting force to be applied to the drive wheels 11 only from the right electric motor 15. As a result, the assist force is applied only to the right drive wheel 11, and the electric assist cart 100 turns to the left by the driving force of the operator and the assist force of the electric motor 15.

  When the operator pushes the operation handle 5 with the right hand and pulls the operation handle 5 backward with the left hand, the right front contact switch 41 is turned on and the left rear contact switch 42 is turned on. It will be switched to. As a result, the controller 30 commands the right electric motor 15 to apply an assist force in the forward direction to the right drive wheel 11, and assists the backward drive direction from the left electric motor 15 to the left drive wheel 11. Command to give power. As a result, assist forces in different directions are applied to the left and right drive wheels 11, and the electric assist cart 100 turns to the left by the driving force of the operator and the assist force of the electric motor 15. At this time, the turning radius of the electric assist cart 100 is minimized.

  If the timing at which the operator pushes the operating handle with the right hand and the timing at which the operating handle 5 is pulled with the left hand are the same, the electric assist cart 100 is placed on the spot around the center between the left and right drive wheels 11. It is possible to turn and change direction without traveling.

  As described above, when the operation handle 5 is pressed by the operator and the contact detection unit 40 detects the contact of the operation handle 5, the output of the electric motor 15 is gradually increased to the maximum value over a predetermined time. By providing the assisting force to the drive wheel 11, even if the contact detection unit 40 only detects the presence or absence of contact without detecting the magnitude of the pressing operation by the worker, there is no sense of incongruity for the worker. Assist power can be applied. Therefore, it is not necessary to use an expensive sensor to detect the magnitude of the pressing operation by the operator, and the electric assist cart 100 can be provided at a low cost.

  Here, when using the torque sensor to detect the magnitude of the driving torque due to the pressing operation of the operator, it is necessary to replace the torque sensor at the time of maintenance and to finely adjust the torque sensor after the replacement.

  On the other hand, in the electric assist cart 100, even if the front contact switch 41 and the rear contact switch 42 are replaced, fine adjustment is not necessary. Therefore, it is possible to reduce the cost and time for maintenance.

According to the above embodiment, the following effects are obtained.
When the operation handle 5 is pressed by the operator and the contact detection unit 40 detects the contact of the operation handle 5, the output of the electric motor 15 is gradually increased to the maximum value over a predetermined time to drive the wheels 11. By providing the assist force to the operator, even if only the presence or absence of contact is detected by the contact detection unit 40 without detecting the magnitude of the pressing operation by the operator, the assist force that does not give the operator a sense of incongruity Granting is possible. Therefore, it is not necessary to use an expensive sensor to detect the magnitude of the pressing operation by the operator, and the electric assist cart 100 can be provided at a low cost.

  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.

DESCRIPTION OF SYMBOLS 100 Electric assist cart 1 Body frame 1a Elongated hole 3 Loading platform 5 Operation handle 7 Torsion bar 11 Drive wheel 12 Universal wheel 15 Electric motor 20 Main body part 30 Controller 40 Contact detection part 41 Front contact switch 42 Rear contact switch 50 Electric assist unit

Claims (5)

An electric assist cart capable of traveling with an assist force applied to a driving force applied by an operator,
A body frame on which luggage can be placed via a loading platform;
A pair of drive wheels provided on the left and right sides of the body frame with a space therebetween;
An operation unit that is pressed by an operator and can input a driving force from two places on the left and right of the body frame, and can be tilted back and forth by the pressing operation;
A pair of contact detection units that are respectively attached to two left and right positions of the body frame so as to come into contact when the operation unit is tilted back and forth, and that detects the contact of the operation unit;
A pair of electric motors that increase the output to a maximum value over a predetermined time and apply assist force to each of the drive wheels when the contact detection unit detects contact of the operation unit; Electric assist cart characterized by The drive wheel is provided so as not to be steered,
The electric assist cart according to claim 1, further comprising a pair of universal wheels mounted on the vehicle body frame and provided behind the drive wheels. The vehicle body frame has a through hole formed with an interval at which the operation portion can be tilted,
The operation part is inserted through the through hole up and down the body frame,
The electric assist cart according to claim 1, wherein the pair of contact detection units are provided below the vehicle body frame. A torsion bar that is provided at a base end of the operation unit and connects the operation unit and the vehicle body frame;
The pair of contact detection units includes a front contact switch and a rear contact switch provided respectively before and after the operation unit, and detects an inclination of the operation unit in the front-rear direction due to twisting of the torsion bar. The electric assist cart according to any one of claims 1 to 3. A controller for controlling the output of the electric motor based on detection of contact of the operation unit by the contact detection unit;
5. The controller according to claim 1, wherein the controller increases the output of the electric motor proportionally to a maximum value by pulse width modulation control when the contact detection unit detects contact of the operation unit. The electric assist cart according to any one of the above.

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