JP2008155780A - Wheel device for carrying vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce wear of caster components and stabilize turning operation. <P>SOLUTION: In this wheel device for a carrying vehicle, drive steering wheels used for both traveling drive and steering and load support wheels 14 are equipped on the bottom part of a carriage frame. The load support wheel 14 comprises a turning frame 21 turnably supported by a vertical support shaft 23, right and left casters 22R, 22L arranged around the support shaft 23 on the turning frame 21 to have an angle of 120° with each other and positioned on right and left sides on the front side in the traveling direction, and a rear caster 22B positioned on the rear side in the traveling direction. The right and left casters 22R, 22L are a turning type in which an idle wheel 34 is supported around a turning shaft 32 to be turnable, and the rear caster 22B is a fixed type in which the rolling direction of an idle wheel 44 is fixed to the forward/backward direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wheel device for a transport vehicle in which a load support wheel provided in a transport vehicle for transporting a load is configured by a plurality of casters.

  Conventionally, Patent Document 1 discloses a conveyance vehicle provided with a multi-wheel traveling unit having a plurality of casters for load support. As shown in FIG. 8, in the multi-wheel traveling part of Patent Document 1 described above, a turning frame 2 is turnably supported via a support shaft 1, and the turning frame 2 has an angle of 120 ° around the support shaft 1. Thus, left and right casters 3R and 3L and a rear caster 3B are provided on an arc C having a turning radius R, respectively. These casters 3R, 3L, and 3B are provided with fork-like support members 5R, 5L, and 5B on the revolving frame 2 around the revolving shafts 4R, 4L, and 4B. The idle wheels 6R, 6L, and 6B are rotatably supported on the free ends of the fork-like support members 5R, 5L, and 5B separated by the radius A.

In this multi-wheel running section, the turning frame 2 is turned around the support shaft 1 following the steering of the bogie frame 2 by the grounding resistance and turning resistance of the idle wheels 6R, 6L, 6B, The fork-like support members 5R, 5L, and 5B are swung around the pivot shafts 4R, 4L, and 4B, respectively, and the left and right casters 3R and 3L are positioned on both sides of the front portion in the traveling direction, and the rear casters 3B are rearward By being positioned, it is configured to maintain a constant traveling posture in which the rotational moments of the casters 3R, 3L, 3B are balanced.
JP 2003-31480 A

  In the above conventional example, the rotating wheels 6R, 6L, 6B of the casters 3R, 3L, 3B are easily turned by the influence of a slight steering force, external force, and obstacles, and are unstable and useless. Due to the large amount of movement, there was a problem that the load applied to the idler wheels 6R, 6L, 6B greatly fluctuated, and the caster parts were easily worn. For this reason, it is necessary to use a caster with a large allowable load and there is a problem that the manufacturing cost is high.

  Furthermore, if the steering wheel is steered, for example, by 90 ° or more before starting to travel, the three casters 3R, 3L, 3B and the turning frame 2 are turned simultaneously, so that the turning frame 2 is turned. There was a problem that it was irregular and easy to become unstable.

  An object of the present invention is to solve the above-mentioned problems and to provide a wheel device for a transport vehicle that can reduce the wear of caster parts, reduce the manufacturing cost, and stabilize the turning operation.

  The invention according to claim 1 is a wheel device for a transport vehicle having a traveling wheel and a steering wheel both for traveling driving and steering, or independently for each of them, and a load supporting wheel at the bottom of the carriage frame. From a revolving frame supported rotatably on a vertical support shaft, a rear caster disposed at a predetermined angle around the support shaft on the revolving frame, and positioned rearward in the traveling direction, A plurality of front casters positioned in front of the running direction, and the rear caster is a fixed type in which the rolling direction of the idler wheel is fixed in the front-rear direction. It is a swivel type that is supported so as to be pivotable about a swivel axis in the vertical direction.

  According to a second aspect of the present invention, in the configuration of the first aspect, the distance from the support shaft to the idler wheel of the fixed rear caster is longer than the distance from the support shaft to the swing shaft of the swivel front caster. It is set.

  According to the first aspect of the present invention, among the plurality of casters arranged at predetermined angles on the revolving frame, the rear caster positioned behind the running direction of the support shaft is used, and the rolling direction of the idler wheel is the front-rear direction. Since the remaining front casters are swivel, the swivel frame can be smoothly swiveled during steering and when starting, and stable steering is possible. The uneven load of the caster parts can be reduced and the wear of the caster parts can be reduced. Further, it is not necessary to use an expensive swivel caster having a large allowable load, and the number of expensive swivel casters can be reduced, thereby reducing the manufacturing cost.

  According to the invention of claim 2, by making the distance from the support shaft to the rear caster longer than the distance from the support shaft to the front caster, it is possible to improve the straight running stability of the load supporting wheel, It is possible to reduce the turning resistance of the caster after the start of turning, and to reduce the driving force at the time of starting.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Embodiment 1]
A wheel vehicle wheel device according to a first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIGS. 3 and 4, at the bottom of the carriage frame 11 of the transport vehicle, two driving steering wheels (traveling wheels) 12 and 13 for both driving and steering are predetermined at the front and rear positions on the right side in the traveling direction. The load supporting wheels 14 and 14 are arranged at a predetermined interval at the front and rear positions on the left side in the traveling direction.

  This transport vehicle is mounted with a load (not shown) on the carriage frame 11 directly or via a lift device (not shown), and is driven by a drive device and a steering device (not shown) based on a radio induction signal or the like. Each of the steering wheels 12 and 13 is operated to travel along the guide line 15 while sensing a predetermined guide line 15 displayed on the traveling surface 16, for example, and transport the load to the destination.

As shown in FIGS. 1 and 2, the load support wheel 14 according to the present invention is provided with a plurality of casters 22 </ b> R, 22 </ b> L, and 22 </ b> B via a turning frame 21 on a carriage frame 11.
The revolving frame 21 is fitted with a vertical support shaft 23 erected at the center of the upper surface in a support hole portion 17 formed in the carriage frame 11 so as to be rotatable and swingable within a predetermined range. Between the carriage frame 11 and the spindle 23, a spherical bearing (also referred to as a thrust bush) 24 that allows the spindle 23 to swing in the front-rear and left-right directions is interposed, and the upper end of the spindle 23 and the carriage A buffer urging tool 25 that allows the support shaft 23 to move up and down and swing is provided between the frame 11 and the frame 11.

  At the bottom of the turning frame 21, it is arranged on the same arc C of the turning radius R centered on the support shaft 23 at equal angles (120 °) about the support shaft 23, and is positioned on both the left and right sides in front of the running direction. The left and right swivel casters (front casters) 22R and 22L, and the fixed rear casters 22B located rearward in the traveling direction.

  Each of the swivel left and right casters 22R and 22L is supported by a mounting seat 31 attached to the bottom of the swivel frame 21 via a swivel shaft 32 in the vertical direction so that the fork-like support member 33 can swivel. An idler wheel 34 is rotatably supported on a free end portion of a fork-like support member 33 separated by a turning radius A via a horizontal wheel shaft 35.

  In the fixed rear caster 22B, a fixed fork-like support member 43 is fixed to a mounting seat 41 attached to the bottom of the revolving frame 21, and an idler wheel 44 is placed on an arc C below the fork-like support member 43. The rolling direction of the idler wheel 44 is fixed in the front-rear direction by being rotatably supported via a horizontal wheel shaft 45.

  In the above configuration, when the vehicle travels straight forward, the idle wheels 34, 34 of the left and right casters 22R, 22L are positioned at symmetrical positions of the travel axis M passing through the support shaft 23, and the idle cast of the rear caster 22B. The wheel 44 is positioned on the traveling axis M behind the support shaft 23, and the rotational moment of the revolving frame 21 around the support shaft 23 generated by each caster 22R, 22L, 22B is balanced, and the revolving frame 21 faces forward. A straight running posture is maintained and the vehicle travels stably.

  During traveling in a steered state where one or both of the drive steering wheels 12 and 13 are steered and the traveling direction is changed during traveling, the traveling direction of the support shaft 23 is changed, so that the turning frame 21 The fork-like support members 33 of the left and right casters 22R and 22L are turned at the same time as the turning frame 21 is turned so that the balance of the turning moments is lost and the turning moments become equal. In the present invention, since the rolling direction of the rear caster 22B is fixed in the front-rear direction from the turning posture to the straight running posture, the frictional resistance of the idle wheel 44 becomes the turning resistance of the turning frame 21. The turning of the turning frame 21 is suppressed, and useless and unstable turning of the turning frame 21 is prevented, whereby the turning frame 21 is stably turned from the turning posture to the straight running posture.

  Further, when the vehicle is stopped, one or both of the drive steering wheels 12 and 13 are largely steered at a turning angle of, for example, 90 ° or more, and when starting in this state, the idle wheels 34 and 44 are respectively set. Since a large frictional resistance is generated, a large starting force is required. Here, as compared with the resistance of the idler wheel 34 of the left and right casters 22R and 22L, the frictional resistance is large because the idler wheel 44 of the rear caster 22B is not turned. The vehicle is turned by adding a resistance of the rotation resistance of the resistance × turning radius R. Therefore, at the time of start in the steered state, the turning frame 21 is stably turned in a certain direction, and the fluctuations of the left and right casters 22R and 22L are reduced, so that the start can be started stably.

  According to the first embodiment, among the casters 22R, 22L, and 22B disposed on the revolving frame 21 at every 120 °, the rear caster 22B that is located rearward in the traveling direction of the support shaft 23 is used to rotate the idler wheel 44. Since the stationary type is fixed so that the moving direction is the front-rear direction, the rear caster 22B serves as a turning resistance of the turning frame 21 during traveling or starting in a turning state in which the drive steering wheels 12 and 13 are turned. The turning of the turning frame 21 can be suppressed. As a result, the turning frame 21 is prevented from turning irregularly due to external forces, obstacles, or turning, and stable running is possible, and uneven loads on the casters 22R, 22L, and 22B can be prevented. Wear can be reduced. Therefore, an expensive caster having a large allowable load is not required, and one expensive swivel caster can be reduced, thereby reducing the manufacturing cost.

  FIG. 6 shows a modification of the first embodiment. In order to improve the load bearing performance of the load supporting wheel 14, the left and right casters 22R and 22L and the rear casters 22B, which are front casters, are each a two-wheel caster. It is what.

  In the first embodiment, the load supporting wheel 14 is constituted by three casters. However, as shown in FIG. 7A, the front caster 22F, the right caster 22R, and the left caster 22L, which are swivel front casters, are used. And a total of four fixed rear casters 22B, or as shown in FIG. 7B, a front right caster 22FR, a front left caster 22FL, a right caster 22R, which are swivel front casters. The left caster 22L is composed of a total of five fixed rear casters 22B. Further, as shown in FIG. 7C, the front right caster 22FR, the front left caster 22FL, which is a swivel front caster, and the right A total of six casters 22R, left casters 22L, fixed right rear casters 22BR, and left rear casters 22BL may be used. In this way, a plurality of fixed rear casters can be provided. Of course, all the casters can also be made into double wheel casters.

[Embodiment 2]
Next, a second embodiment will be described with reference to FIG. The same members as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

This load supporting wheel 14 is configured by rearwardly positioning a rear caster 52 </ b> B provided on the revolving frame 21.
That is, the swiveling left and right casters 22R and 22L are arranged on the arc C so that the turning distance R about the support shaft 23 is the same at a distance of 120 ° from the support shaft 23. On the other hand, the rear casters 52B are arranged 120 ° apart from the support shaft 23 with respect to the left and right casters 22R and 22L, respectively, and the turning distance RB from the support shaft 23 is set longer than the turning radius R of the right casters 22R and 22L. Has been.

  Here, the range of 1.2 to 2.0 × R is appropriate for the turning radius RB from the support shaft 23 of the rear caster 52B. This is because if the turning radius RB is less than 1.2 × R, the effects described later (improvement of straight running stability and reduction of the steering starting force) cannot be sufficiently obtained, and the turning radius BR is 2.0 ×. If R is exceeded, the straightness of the load support wheel 14 becomes too strong, the rear caster 52B is overloaded, and the load support wheel 14 is enlarged.

  In the above configuration, the turning radius RB of the rear caster 52B is set to be longer than the turning radius R of the left and right casters 22R, 22L during traveling, so that the rotational moment with respect to the support shaft 21 that attempts to return to the straight running posture of the rear caster 52B is increased. It is possible to return to the straight running posture in a short time, improve the straight running stability of the load supporting wheel 14, and reduce the irregular turning of the turning frame 21 due to obstacles.

  In addition, since the length of the arm for turning the rear caster 52B (turning radius RB) is large at the start of the turning state, the idle wheel 44 of the fixed rear caster 52B can be turned with a small force. Therefore, even when the vehicle is started in a steered state in which the steered angle is increased to 90 ° or more, it can be started with a small starting force.

  According to the second embodiment, by making the turning radius RB from the support shaft 23 to the rear caster 52B longer than the turning radius R from the support shaft 23 to the left and right casters 22R and 22L, the straight traveling stability of the load supporting wheel 14 is achieved. Can be improved, the vehicle can be returned to a straight running posture in a short time during turning, and traveling stability can be improved. Further, when starting in a steered state that is steered greatly, the idle wheel 45 of the rear caster 52B can be turned with a large torque by the long turning radius RB, and the driving force at the time of activation can be reduced.

Note that the left and right casters 22R and 22L and the rear casters 52B, which are front-side casters, may be double-wheel (two-wheel) type casters.
In the second embodiment, the load supporting wheel 14 is constituted by three casters. However, as shown in FIG. 7D, the front caster 22F, the right caster 22R, and the left caster 22L, which are swivel front casters. And a total of four fixed rear casters 52B, or, as shown in FIG. 7 (e), a front right caster 22FR, a front left caster 22FL, a right caster 22R, which are swivel front casters. The left caster 22L and the fixed rear caster 52B are composed of a total of five. Further, as shown in FIG. 7 (f), the front right caster 22FR, the front left caster 22FL, which is a swivel front caster, and the right A total of six casters 22R, left casters 22L, fixed right rear casters 52BR, and left rear casters 52BL may be used. In this way, a plurality of fixed rear casters can be provided. Of course, all the casters can also be made into double wheel casters.

  Furthermore, in the first and second embodiments, the drive steering wheels 12 and 13 are provided at the front and rear positions on the right side, but the present invention is not limited to such an arrangement. In addition, although the drive steering wheels 12 and 13 that perform both driving and steering are provided, the drive wheels and the steering wheels may be separately arranged.

It is a bottom view which shows Embodiment 1 of the conveyance vehicle which concerns on this invention. It is a side view of the conveyance vehicle. It is a side view which shows a load support wheel. It is a bottom view which shows a load support wheel. It is a bottom view of the load support wheel which shows Embodiment 2 of the conveyance vehicle which concerns on this invention. FIG. 6 is a bottom view of a load support wheel showing a modification of the first embodiment. (A)-(f) is a bottom view which shows the other form of a load support wheel, (a) is what has four casters in the other form of Embodiment 1, (b) is Embodiment 1. (C) has 6 casters in another form of the first embodiment, (d) has 4 casters in the other form of the second embodiment. One having casters, (e) having five casters in another form of the second embodiment, and (f) having six casters in another form of the second embodiment. It is a bottom view which shows the conventional load support wheel.

Explanation of symbols

11 Bogie frames 12, 13 Drive steered wheels 14 Load support wheels 21 Swivel frames 22L, 22R Left and right casters 22B Rear casters 22F Front casters 22FL, 22FR Front left and right casters 22BL, 22BR Rear left and right casters 23 Support shaft 32 Swivel shaft 34 Wheel axle 43 Fork-like support member 44 Idle wheel 45 Wheel axle 52B Rear casters 52BL, 52BR Rear left and right casters

Claims (2)

A wheel device for a transport vehicle including a traveling wheel that performs both driving and steering at the bottom of a carriage frame, or each of them independently and a load supporting wheel,
A swing frame that is rotatably supported by a support shaft in the vertical direction, and a rear caster that is disposed at a predetermined angle around the support shaft on the support frame and that is positioned rearward in the traveling direction; Consists of a plurality of front casters located in front of the rear caster in the running direction,
The rear caster is a fixed type in which the rolling direction of the idler wheel is fixed in the front-rear direction,
The wheel device for a transport vehicle, wherein the front caster is a turning type in which an idler wheel is supported so as to be turnable around a turning shaft in a vertical direction. The wheel device for a transport vehicle according to claim 1, wherein a distance from the support shaft to the idler wheel of the fixed rear caster is set longer than a distance from the support shaft to the swing shaft of the swivel forward caster.

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