JPH0986104A - Caster - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a caster simple in structure, smooth in moving an axle at the time of reversing, without a trouble of sticking and capable of precisely specifying a direction of the axle at the time of moving the axle concerning the caster to prevent revolution of a housing as the axle moves to a biased position on the opposite side along a groove or a slit when a travelling direction of a carriage is reversed. SOLUTION: A rack 6 in parallel with a groove or a slit 5 is arranged above the groove or the slit 5, a pinion 8 to engage with the rack 6 is fixed on both ends of an axle 7, and a wheel 12 is axially fixed on this axle 7 free to rotate on a caster provided with the wheel 12 on a position biased from a revolving shaft 4 in a housing 3 free to revolve around the revolving shaft 4 and provided with the groove or the slit 5 in the horizontal direction to guide the axle 7 to the biased position on the opposite side against the revolving shaft 4 in the housing 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a caster in which wheels are axially mounted on a housing that can swing around a vertical axis.

[0002]

2. Description of the Related Art Caster is widely used as a driven wheel for a hand cart, an automated guided vehicle, or the like. As is well known, the caster is provided with a housing that can be swung (swing) about a vertical axis, and is a structure in which wheels that are freely rotatable about a horizontal axis are provided at positions deviated from the vertical axis of the housing. The housing turns to follow the moving direction of the dolly, and the wheels are oriented in the moving direction of the dolly.

A drawback of the casters is that when the moving direction of the carriage is reversed by approximately 180 degrees, when the wheels are turned in the new moving direction, lateral movement or thrust corresponding to the amount of deviation of the axle from the turning axis occurs. is there. For example, as shown in FIG. 5, one of four wheels supporting the carriage 17 is a driving wheel, the other one is a steering wheel, and the remaining two driven wheels 21 and 22 are casters. In an automatic guided vehicle, when the drive wheels are reversed (reverse) while the bogie is traveling straight, the locus of the ground contact point of the wheels of the casters at the time of reversal becomes the V-shape shown by a in the figure, and the drive wheels are A large lateral force is applied to the steering wheel 18 and the steered wheels 19, and the rubbing marks of the wheels remain as dirt on the floor surface.

As a means for solving this problem, Japanese Unexamined Patent Publication No. Sho.
Japanese Patent Laid-Open No. 8-71203, Japanese Utility Model Laid-Open No. 61-133403, and the like disclose a structure in which the axle of a caster is movably guided along a horizontal groove or slot provided in the housing. In these structures, the moving direction of the carriage is 1
When reversing at an angle close to 80 degrees, the axle moves along a groove or slot in the housing to a biased position on the opposite side of the turning axis. This avoids the generation of lateral force due to turning.

[0005]

However, the direction of the axle with respect to the housing cannot be regulated simply by inserting and supporting both ends of the axle through grooves or slots. Therefore, for example, a structure in which a slide block or the like is provided at the end of the axle and the direction of the slide block is restricted by the housing must be adopted. However, in such a structure, since the movement of the axle along the groove or the long hole becomes a sliding movement, the movement resistance is large and the housing turns without moving the axle, or the slide block does not move in the groove or the long hole. There is a problem that the function of the caster is hindered by sticking on the way.

According to the present invention, when the traveling direction of the bogie is reversed, the axle moves along the groove or the long hole provided in the housing to the bias position on the opposite side to prevent the housing from turning, An object of the present invention is to obtain a caster that has a simple structure and that the movement of the axle along the groove or the long hole is smooth, there is no fear of sticking, and the direction of the axle during this movement can be accurately specified.

[0007]

SUMMARY OF THE INVENTION According to the present invention, a wheel 12 that is rotatable around a swivel axis 4 and is rotatable around an axle 7 in a crossing direction at a position offset from the swivel axis.
And a housing 3 is provided with a horizontal groove or slot 5 for guiding the axle 7 to a biased position on the opposite side to the turning axis, in a caster above the groove or slot 5. A rack 6 parallel to the elongated hole is arranged, pinions 8 meshing with the rack 6 are fixed to both ends of an axle 7, and wheels 12 are rotatably attached to the axle 7. .

In the invention of claim 2 of this application, in the invention of claim 1 described above, when an upward external force is applied to the axle 7, a gap is formed between the axle 7 and the upper edge of the groove or the slot 5. It is characterized in that the rack 6 and the pinion 8 mesh with each other in the state of being left.

The invention according to claim 3 of the present application is the invention according to claim 1 or 2, wherein the brake shoe 13 is supported in a floating manner to provide a rotational resistance of the wheel 12 when the rotational direction of the wheel 12 is reversed. It is characterized by having.

[0010]

According to the first aspect of the invention, the direction of the axle 7 movably mounted along the groove or the elongated hole 5 is accurately defined by the engagement between the rack 6 fixed to both ends of the axle 7 and the pinion 8. As a result, the axle 7 does not loosen in the groove or the elongated hole 5 to cause vibration or rattling in the direction of the wheel, and the axle does not produce a stick when moving along the groove or the elongated hole 5.

According to the second aspect of the present invention, the groove or the elongated hole 5 is formed.
Movement of the axle 7 along the pinion 8 on the rack 6
The rolling resistance of the axle 7 is small, and the pinion 8 and the rack 6 mesh with each other with no clearance, so that the axle 7 can be prevented from swinging or rattling.

According to the third aspect of the present invention, when the traveling direction of the vehicle equipped with the casters of the present invention is reversed, the axle 7 can be moved quickly along the groove or the elongated hole 5, and It is possible to obtain a caster in which the rotational resistance of the wheels during normal traveling is extremely small.

[0013]

1 and 2 are views showing an embodiment of the present invention, FIG. 1 is a side view, and FIG. 2 is a front view showing an axle in cross section. Reference numeral 1 is a mounting bracket for mounting the caster on a dolly, and a housing 3 is provided on the bracket 1 via a swivel bearing 2 so as to be rotatable about a vertical axis. The housing 3 has a symmetrical shape with respect to the swivel axis 4, a front shape is a U-shape, and a side shape is a trapezoid. The housing 3 is formed by bending a sheet metal into a U-shape, and has horizontal elongated holes 5 in the lower side portions of the side plates on both sides.
Is provided. The longitudinal center of the elongated hole 5 coincides with the swivel axis 4 in a side view.

Above the slot 5, a rack 6 fixed in the housing 3 in a direction parallel to the slot 5 is provided. On the other hand, pinions 8 are fixed to both ends of the axle 7,
Both ends of the axle 7 are inserted into the long holes 5, and the pinions 8 at the shaft ends are meshed with the rack 6. The vertical width of the long hole 5 is slightly wider than the diameter of the axle 7, and when an upward force is applied to the axle 7, a slight play is left between the axle 7 and the upper edge 9 of the long hole. Then, the pinion 8 and the rack 6 mesh with each other. That is, the load applied to the axle 7 is received by the rack 6 instead of the elongated hole 5. A wheel 12 is rotatably attached to the axle 7 via a bearing 11.

In the above structure, when the traveling direction of the trolley is reversed and the axle 7 moves along the elongated hole 5, the amount of movement of both ends of the axle is caused by the engagement of the rack 6 and the pinion 8 provided at both ends of the axle. Are exactly the same. Further, since the pinion 8 meshes with the rack 6 and rolls, the movement resistance is small and rattling does not occur.

When such a caster is used, it is preferable that the axle 7 immediately moves from one end of the elongated hole 5 to the opposite end when the traveling direction of the carriage is reversed.
In order to perform this movement promptly, it is effective to give resistance to the rotation of the wheels 12 when the traveling direction is reversed.

FIG. 3 and FIG. 4 show an example of such a structure. The brake shoe 1 is movably provided above the wheels 12 inside the housing 3 in the vertical and horizontal directions.
3 are provided. The length of the brake shoe 13 is slightly shorter than the moving distance of the axle 7.

The upper surface of the brake shoe 13 has a trapezoidal shape with gentle slopes at both ends. Then, on the housing 3 side, the slope 1 facing the slope of the trapezoidal protrusion 14 is formed.
Reference numerals 5 and 16 are formed at a left and right floating clearance L of the brake shoe 13. The brake shoe 13 is mounted, for example, in a structure in which a narrow bracket 24 provided in the housing 3 is locked in a guide hole 23 provided in the middle of the brake shoe 13 and suspended vertically and horizontally so as to be freely movable.

In the above structure, when the wheel 12 rotates at one end of the elongated hole 5 and rotates in the forward direction, for example, when the wheel is at the left end of the elongated hole as shown in FIG. The forward rotation of the wheel 12 around the brake shoe 1
3 is sent to the right. Therefore, the brake shoe 13
The wheel 12 rotates smoothly without hindering the rotation of the wheel 12.

When the traveling direction of the truck is reversed in this state,
The wheels 12 try to rotate counterclockwise in the figure. Due to this reverse rotation, the brake shoe 13 is drawn to the left side, that is, above the wheel 12, as shown in FIG. 4, and due to the trapezoidal shape of the upper surface of the brake shoe and the slope 15 on the left side of the housing. , The brake shoe 13 is pushed downward and pressed against the wheel 12. This prevents the wheel 12 from rotating in the reverse direction, and the wheel 12 moves to the opposite end of the elongated hole 5 due to the movement of the trolley in the state where the wheel is blocked from rotating.

When the wheel 12 moves to the opposite end of the long hole, the reverse rotation direction of the wheel described above becomes forward rotation at this position, and the brake shoe 13 is moved to the left side in the drawing to move the wheel 12 to the left side. Since the wheels 12 are excluded from above, the wheels 12 smoothly rotate without being braked by the brake shoes 13.

The mechanism for applying a resistance force to the wheel 12 as shown in FIGS. 3 and 4 is necessary only when the rotational resistance of the wheel 12 is very small. If it is larger than the rolling resistance of the pinion 8,
There is no need to provide such a mechanism.

[0023]

According to the present invention described above, when the traveling direction of the bogie is reversed, lateral movement or thrust does not occur, the direction of the wheels is accurate, and there is no rattling or wobbling. There is an effect that it is possible to obtain a caster with smooth movement of the axle.

[Brief description of drawings]

FIG. 1 is a side view of an embodiment.

FIG. 2 is a sectional front view of the embodiment.

FIG. 3 is an explanatory diagram of a brake that applies resistance to wheels.

FIG. 4 is an explanatory diagram of a brake that applies resistance to wheels.

FIG. 5 is a diagram showing the lateral movement of the caster when it is inverted.

[Explanation of symbols]

 3 Housing 4 Swivel axis 5 Long hole 6 Rack 7 Axle 12 Wheel 13 Brake shoe

Claims (3)

[Claims] 1. A housing which can be swiveled around a swivel axis (4).
The (3) is equipped with wheels (12) that are rotatable about the axle (7) in the cross direction, which is offset from the turning axis, and
In a caster having a horizontal groove or slot (5) for guiding the axle (7) to an offset position on the opposite side to the turning axis in (3), above the groove or slot (5). The wheel (12) is provided with a rack (6) parallel to the groove or slot arranged and a pinion (8) fixed to both ends of the axle (7) and meshing with the rack (6). 7) A caster characterized by being rotatably attached to (7). 2. The rack (6) and the pinion with a gap left between the axle (7) and the upper edge of the groove or slot (5) when an upward external force is applied to the axle (7). The caster according to claim 1, wherein the caster and (8) mesh with each other. 3. A brake shoe (13), which is supported in a floating manner, which gives a rotational resistance to the wheel (12) when the direction of rotation of the wheel (12) is reversed. The listed casters.