JP2016007266A - Handcart - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a handcart including a novel mechanism allowing front wheels to run on a step and enhancing mobility.SOLUTION: A vehicle body 10 of the handcart includes: front wheels 11 and rear wheels 12. A getting-over-step wheel 20 supported on a base 21 on an undersurface of the vehicle body 10 can change its position forward/backward, and is exerted with a forward biasing force by a biasing force exertion device 24 at all times. The getting-over-step wheel 20 sticks to outside of the base 21 at all times, and is located at a front side of the front wheel 11 even when being retreated maximally. A rotation transmission part 26 is arranged at a rear part of the getting-over-step wheel 20, and the rotation transmission part 26 is connected to an operation force transmission part 31. The getting-over-step wheel 20 retreating against the biasing force is received by the rotation transmission part 26. At this time, if operation force is applied to the operation force transmission part 31, rotation is generated in the rotation transmission part 26, and getting-over-step rotation is generated in the getting-over-step wheel 20 received by the rotation transmission part 26.

Description

  The present invention relates to a wheelbarrow.

  Wheelbarrows are widely used not only for carrying luggage, but also as tools for assisting elderly people and those who have difficulty walking. A wheelbarrow used for walking assistance is sometimes called a senior car. A senior car with an electric assist function has also been developed.

  The road surface on which the wheelbarrow runs (including the indoor floor surface) is not necessarily flat. Often there is a situation where you have to get over the steps. Stepping over a step is one of the important issues to be overcome not only for wheelbarrows but for all vehicles, and many inventions have been made to facilitate this. Examples thereof can be seen in Patent Documents 1 to 3.

  Patent Document 1 describes a wheel support structure that allows a wheel to smoothly run on an obstacle such as a step existing on a road or the like. Here, the wheel, the rotating body having a smaller outer diameter, and the rotating shaft move together, and when the obstacle comes into contact with the wheel, the rotating body contacts the stopper, and the rotating body advances by the stopper. Pushed in the direction. As a result, the wheel and the rotating body move upward over the obstacle, and the wheel rides smoothly on the obstacle.

  Patent Document 2 describes a traveling caster. The traveling caster includes a climbing arm that is pivotable about an arm support shaft on the caster body, and an arm return spring that returns the climbing arm to a non-operating position. When the obstacle reaches the obstacle and the tip of the arm comes into contact, the entire traveling caster is pushed up. After the wheel rides on the obstacle, the overpass arm is returned to its original position by the arm return spring.

  Patent Document 3 describes a carriage. In this carriage, an L-shaped support arm is rotatably attached to a rear end portion on the back surface. The support arm has an L-shaped short side at the base side and an L-shaped long side at the tip side, and auxiliary wheels are attached to the short side, the corners of the long side, and the tip of the long side, respectively. If you encounter a step, you can lift the front part of the cart to the level of the step by placing the foot on the long side of the support arm, grounding the auxiliary wheel at the tip of the long side, and tilting the handle of the cart toward you.

JP 2006-27336 A JP 2004-106803 A JP-A-9-188258

  The key to overcoming the step of a wheelbarrow is how to smoothly move the front wheel on the step. An object of the present invention is to provide a handcart having a new mechanism for causing a front wheel to climb up a step and having further improved mobility.

  A wheelbarrow according to the present invention includes a vehicle body having front and rear wheels, a base attached to a lower surface of the vehicle body, a step-over wheel that is supported by the base and can be repositioned forward and backward, and the step-over wheel. An urging force applying device that constantly applies an urging force to the front, a rotation transmission portion that receives the step overcoming wheel when the step overcoming wheel retreats against the urging force, and an operation connected to the rotation transmission portion A force transmission part, and the wheels overcoming the step always protrude outside the base and are located forward of the front wheels even when they are fully retracted, and an operation force is applied to the operation force transmission part. Rotation occurs in the rotation transmission portion, and thereby, the rotation over the step occurs in the step overcoming wheel received by the rotation transmission portion.

  According to this configuration, the step-over wheel is actively rotated over the step, and the step-over wheel can be smoothly and reliably mounted on the step.

  In the handcart having the above-described configuration, it is preferable that a relative position in the front-rear direction between the vehicle body and the base is unchanged, and a relative position in the front-rear direction between the base and the stepping wheel is variable.

  According to this configuration, it is possible to easily obtain a front-rear direction position variable structure of the wheel over the step.

  In the wheelbarrow having the above-described configuration, it is preferable that the relative position in the front-rear direction between the base and the stepped wheel is invariable, and the relative position in the front-rear direction between the vehicle body and the base is variable.

  According to this configuration, it is possible to easily obtain a front-rear direction position variable structure of the wheel over the step.

  In the handcart having the above-described configuration, it is preferable that the operating force transmission unit is configured with a power point portion as a pedal.

  According to this configuration, a strong operating force can be easily obtained.

  In the wheelbarrow having the above-described configuration, it is preferable that the rotation transmission from the rotation transmission unit to the stepped wheel is performed by meshing of gears.

  According to this configuration, rotation transmission is reliably performed.

  In the handcart having the above-described configuration, it is preferable that the rotation transmission from the rotation transmission unit to the wheel over the step is performed by friction.

  According to this configuration, rotation transmission can be performed by a cost-effective mechanism.

  In the handcart having the above-described configuration, it is preferable that an engagement force increasing process is performed on an outer peripheral surface of the stepped wheel.

  According to this configuration, it is possible to prevent slipping when the wheels over the step climb on the step.

  In the handcart having the above-described configuration, it is preferable that an operation force applied to the operation force transmission unit is also used to rotate the rear wheel in a forward direction.

  According to this configuration, the step-up wheel can be easily climbed on the step by applying the propulsive force by the rear wheel.

  In the present invention, when the wheel over the step hits the step, the wheel over the step is moved backward relatively by further pushing the wheelbarrow, and when the wheel over the step is received by the rotation transmission unit, the operation force is transmitted to the operation force transmission unit. The rotation transmission part is caused to rotate, and this rotation is converted into an active step overturning rotation of the wheel over the step, so the step overstep is different from simply pushing the wheel over the step and getting on the step. Stepping of the wheel step is smooth and reliable, and stepping of the front wheel with the wheel over the step leading is also smooth and reliable.

It is a perspective view of the wheel part of the handcart which concerns on 1st Embodiment of this invention. It is 1st operation | movement explanatory drawing of the said wheel part. It is 2nd operation | movement explanatory drawing of the said wheel part. It is 3rd operation | movement explanatory drawing of the said wheel part. It is a perspective view of the wheel part of the handcart which concerns on 2nd Embodiment of this invention.

(First embodiment)
The basic structure of the handcart according to the present invention will be described with reference to FIGS. FIG. 2 shows a vehicle body 10 serving as a base portion of a wheelbarrow (senior car) for assisting elderly people and those who have difficulty walking. A handle portion for pushing and steering the vehicle body 10 is provided at the rear upper surface of the vehicle body 10, but this is not shown.

  FIG. 1 shows a wheel structure for supporting the vehicle body 10. The vehicle body 10 is supported at four points by two front wheels 11 and two rear wheels 12. The rear wheel 12 has a larger diameter than the front wheel 11. The front wheel 11 is composed of casters.

  One step climbing wheel 20 is disposed between the two front wheels 11. A base 21 composed of two plates arranged in parallel hangs down from the lower surface of the vehicle body 10, and a step-over wheel 20 is supported at the lower end of the base 21 so as to be sandwiched between the two plates. . The step overcoming wheel 20 is slightly smaller in diameter than the front wheel 11. Further, the step-over wheel 20 is not always in contact with the road surface like the front wheel 11 but is supported at a position slightly lifted from the road surface.

  The base 21 is fixed to the vehicle body 10, and no relative movement occurs between the base 21 and the vehicle body 10. On the other hand, the axle 22 of the stepped wheel 20 is engaged with a horizontal slot 23 formed in the base 21 so as to extend in the front-rear direction. As a result, the step-over wheel 20 can change the relative position in the front-rear direction with respect to the base 21 with the horizontal length of the long hole 23 as the movement limit.

  The stepping wheel 20 is always given forward biasing force by the biasing force applying device 24. A tension coil spring that connects the base 21 and the axle 22 constitutes an urging force applying device 24.

  The axle 22 is normally attracted to the front end of the long hole 23 by the urging force applied by the urging force applying device 24. This state is the normal position of the wheel 20 over the step. In the normal position, the front part and the lower part of the wheel 20 that oversteps the step protrude outside the base 21. The front surface of the stepped wheel 20 is positioned in front of the front surface of the front wheel 11.

  When the step-overcoming wheel 20 moves backward and the axle 22 reaches the vicinity of the rear end of the long hole 23, the lower portion of the step-overpassing wheel 20 protrudes outside the base 21 as shown in FIG. In other words, at least the lower part of the step overcoming wheel 20 always protrudes outside the base 21.

  The step overcoming wheel 20 has a smaller diameter than the front wheel 11, but even when the step over wheel 20 is fully retracted, that is, when the axle 22 has moved to the rear end of the long hole 23, Is located in front of the front surface of the front wheel 11.

  Engagement force enhancement processing is performed on the outer peripheral surface of the wheel 20 over the step so as to make it easy to climb over the step. Specifically, the engagement force increasing process is to form a concavo-convex pattern such as an automobile tire or to form a contact surface having a large friction coefficient.

  A gear 25 is fixed to the side surface of the stepped wheel 20 so as to be concentric therewith. The gear 25 has a diameter smaller than that of the wheel 20 over the step, and rotates together with the wheel 20 over the step. A configuration in which the gear 25 is integrally formed with the stepped wheel 20 may be employed.

  Behind the base 21 is disposed a rotation transmission portion 26 that receives the step-over wheel 20 when the step-over wheel 20 moves backward against the urging force of the urging force applying device 24. The rotation transmission unit 26 is configured by a sector gear that receives and meshes with the gear 25. The rotation transmitting portion 26 is fixed to the action point portion at the front end of the lever 27.

  The lever 27 is a seesaw lever, and an intermediate fulcrum portion is supported by a stay 28 suspended from the lower surface of the vehicle body 1 and is rotatable in a vertical plane. The tooth tip of the rotation transmitting portion 26 draws an arc centered on the fulcrum portion of the lever 27. The force point portion at the rear end of the lever 27 is connected to the action point portion at the front end of the relay lever 29 which is also a seesaw lever.

  The relay lever 29 is supported by an intermediate fulcrum portion on a stay 30 that hangs down from the lower surface of the vehicle body 1 and is rotatable in a vertical plane. The action point portion at the front end of the operating force transmission portion 31 is connected to the force point portion at the rear end of the relay lever 29. That is, the operating force transmission unit 31 is connected to the rotation transmission unit 26 via the relay lever 29.

  The operating force transmission portion 31 is also configured as a seesaw lever, and an intermediate fulcrum portion is supported by a stay 32 suspended from the lower surface of the vehicle body 1 so as to be rotatable in a vertical plane. The power point portion at the rear end of the operating force transmission portion 31 is configured as a pedal 33.

  As shown in FIG. 1, the members of the lever 27, the relay lever 29, and the operating force transmission unit 31 are all horizontal when the step-over wheels 20 are not hitting the step and the foot is not placed on the pedal 33. Keep posture close to. In other words, the weight balance of each member is adjusted so that such a state is obtained.

  The operation of the wheel portion of the vehicle body 10 is as follows. In a state where the step climbing wheel 20 does not hit the step, the urging force applying device 24 attracts the front end of the long hole 23 of the base 21 so that the front portion and the lower portion protrude outside the base 21. The gear 25 is separated from the rotation transmission unit 26. At this time, the operating force transmission unit 31 is in a horizontal posture, and the pedal 33 is lifted from the road surface.

  When the step 40 is present on the road surface on which the vehicle body 10 travels, the front of the step overcoming wheel 20 is positioned ahead of the front of the front wheel 11 as described above, so the step over wheel 20 is stepped ahead of the front wheel 11. 40 hits. When the vehicle body 10 is pushed forward as it is, the tension coil spring constituting the urging force applying device 24 is extended, and the step overcoming wheel 20 is moved backward relative to the stay 21 and thus relative to the vehicle body 10. When the axle 22 moves to the vicinity of the rear end of the long hole 23, the gear 25 hits the rotation transmission unit 26, and the gear 25 is received by the rotation transmission unit 26. The teeth of the gear 25 and the teeth of the sector gear constituting the rotation transmitting portion 26 are engaged with each other here.

  When the teeth of the gear 25 and the teeth of the rotation transmitting portion 26 are engaged, the pedal 33 is depressed. Then, in FIG. 2, the operating force transmission unit 31 is rotated clockwise around the intermediate fulcrum. The relay lever 29 connected to the operating force transmission unit 31 rotates counterclockwise around the intermediate fulcrum. The lever 27 connected to the relay lever 29 is rotated clockwise around the intermediate fulcrum.

  When the rotation transmitting portion 26 together with the lever 27 rotates clockwise in FIG. 2, the gear 25 rotates counterclockwise, and the step overcoming gear 20 also rotates counterclockwise. This rotation is the rotation in the direction over the step 40, that is, the rotation over the step. Thus, the wheel 20 that has climbed over the step climbs up to the step 40 by itself by actively rotating over the step. As described above, since the engagement force increasing process is performed on the outer peripheral surface of the stepped wheel 20, the stepped wheel 20 rides on the step 40 with strong force.

  As shown in FIG. 3, the front wheel 11 starts to ride on the corner of the step 40 in the form of being led by the stepped wheel 20. As a result, the front wheel 11 pushes up the vehicle body 10 and the wheel 20 over the step is pulled up. When the step climbing wheel 20 completely floats from the step 40, the urging force applying device 24 pulls the step climbing wheel 20 forward, and disconnects the gear 25 from the rotation transmitting portion 26. When the foot is released from the pedal 33, the operating force transmission mechanism from the pedal 33 to the rotation transmission unit 26 returns to the state before the rotation transmission unit 26 receives the gear 25.

  As shown in FIG. 4, after the front wheel 11 has completely climbed the step 40, if the vehicle body 10 is further pushed forward, the rear wheel 12 can also climb the step 40. The rear wheel 12 having a large diameter can be easily ridden on the step 40 without the help of the wheel 20 over the step.

(Second Embodiment)
A second embodiment of the present invention is shown in FIG. In the description of the second embodiment, the lever 27, the stay 28, the relay lever 29, and the stay 30 are not shown.

  The second embodiment is different from the first embodiment in that the operation force applied to the operation force transmission unit 31 is also used to rotate the rear wheel 12 in the forward direction. The specific mechanism is as follows.

  A gear 34 is arranged on the side surfaces of the two rear wheels 12 facing each other so as to be concentric with the side surfaces. Between the gear 34 and the rear wheel 12, a unidirectional rotation mechanism (not shown) similar to the free wheel structure used to transmit the pedaling force to the rear wheel of the bicycle is provided. That is, in FIG. 5, the rotation when the gear 34 rotates counterclockwise is transmitted to the rear wheel 12, but the rotation when the gear 34 rotates clockwise is not transmitted to the rear wheel 12.

  A cross bar 35 is formed at a position between the fulcrum portion and the pedal 33 in the operating force transmission portion 31. A fan-shaped gear 36 that meshes with the gear 34 from the front is formed at the tip of the cross bar 35. The tooth tip of the sector gear 36 draws an arc centered on the fulcrum part of the operating force transmission part 31.

  The sector gear 36 is always meshed with the gear 34. When the handcart is pushed, the gear 34 does not rotate, while the rear wheel 12 tries to rotate in the forward direction. Since the one-way rotation mechanism between the gear 34 and the rear wheel 12 allows the rear wheel to rotate at this time, as in the case of pushing the bicycle, the handcart can move forward without any problem.

  When the pedal 33 is depressed when the stepped wheel 20 hits the step 40, the stepped wheel 20 is rotated over the step. At this time, the fan gear 36 also rotates about the fulcrum portion of the operating force transmission portion 31 and the rotation is transmitted to the gear 34, and the gear 34 rotates counterclockwise in FIG. The rotation of the gear 34 in this direction is transmitted to the rear wheel 12 by a one-way rotation mechanism, and the rear wheel 12 actively rotates in the forward direction.

  The amount of advancement of the rear wheel 12 caused by the rotation angle of the rear wheel 12 at this time is set larger than the amount of advancement of the stepping wheel 20 brought about by the rotation angle of the stepping wheel 20 that rotates simultaneously. As a result, the step overcoming wheel 20 receives a propulsive force from the rear wheel 12. As a result, the wheel 20 that steps over the step 20 actively rides over the step and rotates forward, and the forward driving force by the rear wheel 12 is also applied to easily climb on the step 40.

  When the front wheel 11 rides on the step 40 and the gear 25 of the wheel 20 over the step moves away from the rotation transmitting portion 26 and then releases the foot from the pedal 33, the operating force transmitting portion 31 returns to the initial angle, and in the process, the sector gear 36 rotates the gear 34 clockwise. When the gear 34 rotates in this direction, the gear 34 is separated from the rear wheel 12 by the one-way rotating mechanism, so that the gear 34 and the operating force transmission unit 31 can return to the initial posture without any trouble.

  In addition to the structures of the first and second embodiments, various structural modifications are possible. Some of such modifications will be introduced below as embodiments below the third embodiment.

(Third embodiment)
The stepped wheel 20 needs to move backward when it hits the step. In order to make it possible, the relative position of the vehicle body 10 and the base 21 in the front-rear direction is not changed, while the axle 22 of the wheel 20 is engaged with the horizontal long hole 23 formed in the base 21 over the step. The relative position in the front-rear direction between the base 21 and the step-over wheel 20 is variable, but this configuration can be changed as follows.

  In other words, it is assumed that the base 21 receives the axle 22 of the step-over wheel 20 in a circular hole instead of a long hole, and the relative position in the front-rear direction between the base 21 and the step-over wheel 20 is unchanged. Instead, the base 21 can be slid back and forth with respect to the vehicle body 10, and the urging force applying device 21 is interposed between the vehicle body 10 and the base 21 to urge the base 21 itself forward. The step overcoming wheel 20 always protrudes not only from the lower part but also from the front part to the outside of the base 21.

(Fourth embodiment)
The rotation transmission from the rotation transmission unit 26 to the stepped wheel 20 has been performed by meshing the sector gear constituting the rotation transmission unit 26 with the gear 25, but it is also possible to perform this by friction. . That is, the sector gear is changed to a toothless plate and the gear is changed to a toothless disc. This configuration can be realized by setting the coefficient of friction between the sector plate and the disk sufficiently high.

(Fifth embodiment)
In the embodiments so far, the operation force applied to the operation force transmission unit 31 has been a stepping force by a foot. This forces the operator to stand on one foot, but if the operator is an elderly person or a person with difficulty walking, there may be situations where the operator cannot stand on one foot. Therefore, a configuration in which a force other than the foot pedal force is used as the operating force is referred to as a fifth embodiment. The lever force operated by hand or the operating force of an actuator driven by a battery can be used as the operating force other than the treading force if the handcart has an electric assist function. It is good also as a structure which can use together operation force other than pedaling force, and pedaling force.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

  The present invention is widely applicable to a wheelbarrow.

DESCRIPTION OF SYMBOLS 10 Car body 11 Front wheel 12 Rear wheel 20 Step overcoming wheel 21 Base 24 Energizing force giving device 25 Gear 26 Rotation transmission part 31 Operation force transmission part 33 Pedal

Claims (8)

A vehicle body with front and rear wheels;
A base attached to the lower surface of the vehicle body;
Stepped wheels that are supported by the base and can be repositioned back and forth,
An urging force imparting device that constantly imparts an urging force forward to the stepping wheel;
A rotation transmitting portion for receiving the stepped wheel when the stepped wheel is retracted against the biasing force;
An operating force transmission unit coupled to the rotation transmission unit;
With
The step climbing wheel always protrudes to the outside of the base, and is located forward of the front wheel even when it is fully retracted,
When the operating force is applied to the operating force transmission unit, the rotation transmission unit is rotated, and thereby the step wheel is rotated over the stepped wheel that is received by the rotation transmitting unit.   The handcart according to claim 1, wherein a relative position in the front-rear direction between the vehicle body and the base is unchanged, and a relative position in the front-rear direction between the base and the stepped wheel is variable.   2. The handcart according to claim 1, wherein a relative position in the front-rear direction between the base and the stepped wheel is unchanged, and a front-rear relative position between the vehicle body and the base is variable.   The handcart according to any one of claims 1 to 3, wherein the operating force transmission unit includes a force point portion as a pedal.   The wheelbarrow according to any one of claims 1 to 4, wherein the rotation transmission from the rotation transmission unit to the stepped wheel is performed by meshing of gears.   The handcart according to any one of claims 1 to 4, wherein the rotation transmission from the rotation transmission unit to the wheel over the step is performed by friction.   The handcart according to any one of claims 1 to 6, wherein an engagement force increasing process is performed on an outer peripheral surface of the stepped wheel.   The handcart according to any one of claims 1 to 7, wherein an operation force applied to the operation force transmission unit is also used to rotate the rear wheel in a forward direction.

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