JP4458960B2 - Buffer caster - Google Patents

Description

  The present invention relates to a shock-absorbing caster suitable as a wheel for various transport carts and the like.

The caster has a shock absorbing mechanism in order to absorb and soften the shock when the wheel rolls on the road surface or the floor and goes down the step or gets over the step.
2. Description of the Related Art Conventionally, as a structure for cushioning, there is a structure including a fork that is rotatably connected to a bracket and supports a wheel, and a cushion rubber or a buffer spring interposed between the bracket and the fork.

However, in such a conventional caster, the load and the impact absorption effect determined by the spring characteristics are determined, and in particular, a shock absorbing spring or the like is manufactured with a focus on a heavy load.
Therefore, in the case of empty load or light load, even if the caster is attached to the four wheels on the carriage, it will be grounded on three wheels, and the load will not be applied so that one wheel will lift and the cushioning material will operate, causing vibration and noise. . For this reason, it was unsuitable for conveyance of the object etc. which require precision, such as lightweight precision instrument parts and medical equipment which are weak also to a slight vibration.

  On the other hand, if the main point is placed when a light load is applied, a problem arises that if a heavy load is applied, the cushioning material is too soft and sinks.

In view of this, as a caster capable of obtaining a spring characteristic and a shock absorbing characteristic suitable for a mounting load, a caster with a shock absorber disclosed in Japanese Patent Laid-Open No. 2003-165302 has been proposed.
This caster includes a hydraulic damper that expands and contracts as the arm swings, and includes an attachment angle adjustment mechanism that encloses a high-viscosity hydraulic oil in the hydraulic damper and adjusts the attachment angle of the hydraulic damper.
Thus, the high-viscosity hydraulic oil having a high compressibility achieves the function of a spring that supports the mounting load applied to the caster and the damper function that attenuates the vibration of the arm.

However, there is a hassle of having to change the mounting angle of the hydraulic damper according to the increase or decrease of the load, and the structure of the caster itself is complicated, which increases the manufacturing cost of the caster and the failure frequency Have problems.
JP 2003-165302 A

  From the above points, the present invention has a spring characteristic according to the load at the time of empty load, light load and heavy load without using various attenuators such as a hydraulic damper, and a buffer capable of reducing the impact. It is intended to provide casters.

In order to solve the above problems, a shock absorber according to a first aspect of the present invention includes a bracket attached to the vehicle body side, a fork that pivotally supports an axle of a wheel and rotatably holds the wheel, and the fork is attached to the bracket. And a fork swinging from the start position to the end position within a predetermined load range at light load. And has a restricting means for restricting the shaft, and is pivotally supported by the swing shaft so that the load can be swung together with the fork from the end point position of the axle with respect to a load exceeding the predetermined load range. A stopper that is provided on the bracket and starts to swing from a swing start position to a swing stop position when a part of the swing member collides with the bracket. Comprising the predetermined load Operating at a load of囲内biases the axle to the start position, operating against a load exceeding a first biasing member interposed between the fork and the swinging member, the predetermined load range, The oscillating member is urged together with the fork toward the oscillating start position of the oscillating member, and a second urging member interposed between the oscillating member and the bracket is provided. It is.

With such a configuration, the bracket is used as a wheel device by attaching it to the vehicle body side such as a carriage, and when this wheel collides with the road surface or the like and receives external force, the fork resists the urging force of the urging member. However, the present invention regulates the swing of the fork from the start position to the end position within a predetermined load range from empty load to light load. The biasing member expands and contracts by operating with a load within this range.
Since the first urging member is provided, the impact is absorbed by this deformation even at light load, and the axle is returned to the starting position by its restoring force, and the urging member is operated even at an empty load such as a carriage. The wheels are pressed against the ground, preventing the bogie from shaking.

In addition, when the load exceeds a predetermined load range, when the axle swings from the start point position to the end point position, the first urging member similar to the previous one operates to perform the initial operation, and then the swing member A further oscillating axle starts to oscillate together with the fork from the end position of the axle, and a second urging member is provided that operates and elastically deforms against a load exceeding the predetermined load range. Therefore, sinking is prevented corresponding to this load, the impact is absorbed by elastic deformation, and the swinging member is returned to the swing start position together with the fork by the restoring force.
Therefore, the initial operation is good when the load is light, and subsidence is prevented when the load is exceeded, and an elastic characteristic and a buffering action corresponding to the load are obtained.

Next, a shock absorber according to a second aspect of the present invention is the shock absorber according to the first aspect, wherein the restricting means is formed on the swing member and extends in the same direction as the swing direction of the fork with the swing shaft as a center. It is a substantially arc-shaped guide groove, and the axle is fitted into the guide groove, and the guide groove has a start end surface on which the axle is abutted when the axle is at the start position, and an axle when the axle is at the end position. It has a termination face to be abutted.

With this configuration, when the fork is swung around the swing shaft, the axle slides in the guide groove while being fitted in the guide groove.
When the fork reaches the start position, the axle is brought into contact with the start end face of the guide groove. When the fork reaches the end position, the axle is brought into contact with the end face of the guide groove, and is within the range between the start position and the end position. The swing is limited by.

  Next, the shock absorber of the present invention according to claim 3 is the shock absorber according to claim 1 or 2, wherein the first biasing member is a tension spring interposed between the fork and the swing member. It is characterized by.

  With such a configuration, when the fork starts swinging from the start point side to the end point side about the swing axis, the pulling spring extends, and the fork is moved to the starting point position side by the restoring force of the pulling spring. Be energized.

  Next, a shock absorber according to a fourth aspect of the present invention is the shock absorber according to any one of the first to third aspects, wherein the second urging member is a push spring interposed between the swinging member and the bracket. It is characterized by being.

  With such a configuration, when the swing member starts swinging from the end point position side of the axle toward the stopper side, the push spring is contracted, and the swing member is swung by the restoring force of the push spring. It is biased toward the movement start position.

  According to the shock-absorbing caster of the present invention, the caster is used as a wheel of a cart or the like, and the load applied to the wheel has a spring characteristic corresponding to a load within a predetermined range from an empty load to a light load. In addition to the first urging member, a second urging member having a spring characteristic corresponding to the first urging member cushions against a load exceeding this load range. The stage can be buffered, the spring is too hard and the initial operation is not deteriorated, the spring is too soft and the sinking does not occur, let alone heavy load, light load on the load etc. Even at times, the spring characteristics and buffering action corresponding to it work, all wheels are pressed against the ground, and it has the effect that it is difficult for vibrations such as carts to occur, so light weight precision equipment that is weak against slight vibrations Precision of parts and medical equipment is required From the conveying elephant product has an effect that can accommodate a wide range of load to heavy load carrying.

Further, the urging member uses a tension spring and a push spring, and does not use an attenuator, so that the structure of the caster itself can be simplified.
Therefore, the production cost of the caster itself can be reduced, and the caster itself can be hardly broken down.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view taken along the line B-B showing an embodiment of the buffer caster of the present invention.
The caster 1 is attached to an object (not shown) such as a carriage and used as a wheel of the object.
The caster 1 includes a plate 2 attached to a vehicle body such as a carriage, a bracket 4 coupled to the plate 2 via a bearing 3 so as to be pivotable in a horizontal direction, a fork 5 coupled to the bracket 4 so as to be swingable, The fork 5 includes a wheel 6 that is pivotally supported by the fork 5.

The bracket 4 is formed in a substantially circular shape having side walls 4a on both sides and has a rear wall 4b, and is rotated in the horizontal direction so that the wheel 6 faces the traveling direction.
Further, when the fork 5 swings up and down with respect to the bracket 4, the wheel 6 moves up and down.

The fork 5 is passed between the side plates 5a on both sides that are long in the front-rear direction, in which the base side is disposed so as to approach the inside of the side walls 4a of the bracket 4, and to the front portion that extends further forward than the bracket 4 of the side plate 5a. It is formed from a connecting plate 5b that connects the provided side plates 5a.
Then, the fork 5 swings on the base side, leaving the base end portion of the side plates 5a, via a bearing 8 (FIG. 5) on a swing shaft 7 having a circular cross section provided between the lower portions of both side walls 4a of the bracket 4. It is supported freely.
Further, an axle 9 having a circular cross section for pivotally supporting the wheel 6 is provided in a lower portion between the side plates 5a of the fork 5 so that the wheel 6 can be pivoted. The wheel 6 can be pivoted to the axle 9 via a bearing 10. (FIG. 5).

  A swing member 11 is pivotally supported on the swing shaft 7 so as to be swingable. The swinging member 11 has side plates 11a on both sides. The side plate 11a is disposed on the front side between the side plate 5a of the fork 5 and the wheel 6, and the lower portion on the front side is a guide groove 14 provided on the side plate 11a described later. An axle 9 is inserted into the shaft. The lower part of the side plate 11 a on the base end side is pivotally supported on the swing shaft 7 via a bearing 13.

Further, a notch recess 11b is formed in the substantially central portion of the upper edge of the side plate 11a, and the side plates 11a on both sides are connected between the side plates 11a on the front side (wheel mounting side) of the notch recess 11b. A front collision plate 11c is provided.
The front collision plate 11c is provided in a state where the upper part is inclined forward, and when the swinging member 11 is rotated clockwise about the swinging shaft 7, the front collision plate 11c is formed on the front upper part between the side walls 4a of the bracket 4. It is arranged so as to collide with a front stopper 12 composed of a horizontally extending bolt shaft, and the swinging member 11 is restricted from turning clockwise by this front stopper 12.
A rear stopper 15 made of a bolt shaft provided between the side walls 4 a of the bracket 4 is inserted into the notch recess 11 b in parallel with the front stopper 12.

Further, a rear collision plate 11d for connecting the side plates 11a on both sides is provided between the side plates 11a on both sides at the rear edge of the notch recess 11b.
The rear collision plate 11d is provided in a substantially vertical state, and is arranged so as to collide with the rear stopper 15 when the swinging member 11 swings counterclockwise. The rear stopper 15 causes the swinging member 11 to be anti-reverse. The swinging in the clockwise direction is restricted.

A substantially arcuate guide groove 14 that is long in the vertical direction about the swing shaft 7 is provided in the lower portion on the front side of the side plate 11 a on both sides of the swing member 11.
The guide groove 14 is a groove extending in the same direction as the swinging direction of the fork 5, and the axle 9 is slidably inserted between the guide grooves 14 on both sides. A reinforcing piece 16 is attached to the outer edge of the guide groove 14.

  FIG. 1 shows a state in which the axle 9 is at the starting point position of the guide groove 14, that is, the fork 5 is at the starting point position. The guide groove 14 is closed at both ends in the longitudinal direction, the lower side is the starting end surface 14a, and the upper side is the end surface. 14b, and both end surfaces 14a, 14b are formed on circumferential end surfaces that match the peripheral surface of the axle 9 so that the axle 9 abuts.

Further, a pin 17 projects inward from the base end portion of the side plate 5a on both sides of the fork 5 (the end portion on the opposite side of the mounting side of the wheel 6 with respect to the swing shaft 7) in a direction orthogonal to the side plate 5a. At the same time, a pin 18 protrudes from the upper part of the base end portion of the side plate 11a of the swing member 11 toward the outside (side plate 5a side of the fork 5) perpendicular to the side plate 11a (FIG. 4).
A first urging member 19 is interposed between the pins 17 and 18 such that both ends thereof are fixed to the pins 17 and 18.
The first urging member 19 is a coiled spring, and the first urging member 19 urges the fork 5 counterclockwise, that is, urges the axle 9 toward the start position of the guide groove 14. Yes.

  When this first urging member 19 is used for a wheel such as a carriage, it has a soft spring characteristic corresponding to the load so that it operates when the load within a predetermined load range from an empty load to a light load is small. Is set to

Further, a pin shaft 20 projects from the center of the rear collision plate 11d of the swing member 11 toward the rear wall 4b of the bracket 4, and the pin shaft 20 faces the pin shaft 20 and faces the rear wall 4b of the bracket 4. 21 protrudes (FIG. 4). A second urging member 22 is interposed between the pin shafts 20 and 21 (FIG. 4).
The second urging member 22 is a coiled push spring, and both end portions are fitted to the outside of the pin shafts 20 and 21.
The second urging member 22 urges the swing member 11 counterclockwise, that is, urges the swing member 11 toward the swing start position. It collides with the rear stopper 15 and further swinging is restricted, and this is the swing start position.
The end position of the swing member 11 is a position where the front collision plate 11c of the swing member 11 collides with the stopper 12, and the swing member 11 swings within this range.

  The second urging member 22 is set to have a hard spring characteristic so as to operate when the first urging member 19 exceeds the corresponding load range and the mounting load is large, and the first urging member 19 is activated. It is set so as not to be elastically deformed within a predetermined load range from loading to light loading.

Next, the usage method of the caster which has the above structure is demonstrated based on drawing.
FIG. 1 shows a state in which no load is applied to the caster 1 itself. This caster 1 is attached to the lower surface of a carriage (not shown) or the like.
FIG. 2 shows a state where the load during light load is small from when it is empty, and the fork 5 swings from the start position to the end position.

As the fork 5 swings, the axle 9 slides from the start end surface 14a of the guide groove 14 toward the end end surface 14b. The first energizing member that operates with a light load by the slide of the axle 9 is provided. The tension spring 19 is extended and elastically deformed, so that the impact is absorbed. At this time, the second urging member 22 is not elastically deformed.
A restoring force is generated in the first urging member 19 along with the elastic deformation, and a force for returning the starting point to the fork 5 about the swing shaft 7 is applied to the fork 5.

FIG. 3 shows a state when the load is large. First, as shown in FIG. 2, the fork 5 swings from the start position to the end position as shown in FIG. 2, and the first urging member 19 extends. By the elastic deformation, the initial operation for absorbing the impact is satisfactorily performed.
Here, when the load exceeds a predetermined load range, as a second stage, the fork 5 further swings in the clockwise direction.
At this time, since the axle 9 abuts the end surface 14b of the guide groove 14 of the swing member 11, the axle 9 swings the swing member 11 in the same direction.
By the swinging of the swinging member 11, the push spring as the second urging member 22 is contracted and elastically deformed, so that the impact is absorbed. The second urging member 22 corresponds to a load exceeding a predetermined load range, and excessive sinking is prevented.
The first urging member 19 is further extended by the swing of the swing member 11. The swing of the swing member 11 is from the end point position of the axle 9 until the front collision plate 11 c of the swing member 11 collides with the front stopper 12.

  With the elastic deformation, a restoring force is generated in the second urging member 22, and a restoring force is applied to the oscillating member 11 around the oscillating shaft 7 along with the fork 5 toward the end point of the axle 9. The rear collision plate 11d of the moving member 11 collides with the rear stopper 15 and stops, the swinging member 11 is returned to the swing start position, and the first biasing member 19 biases the axle 9 toward the starting position. Then, the fork 5 is returned.

  Although the present invention has been specifically described above based on the embodiments, the present invention is not limited to the above-described embodiments, and various improvements and modifications can be made without departing from the spirit of the present invention. . For example, casters can be used not only for carts but also for strollers, wheelchairs, and the like.

It is sectional drawing which showed the effect | action of this invention buffer caster and followed BB of FIG. It is sectional drawing which showed the effect | action of this invention buffer caster and followed BB of FIG. It is sectional drawing which showed the effect | action of this invention buffer caster and followed BB of FIG. It is a cross-sectional top view of this invention buffer caster. It is sectional drawing along AA of FIG.

DESCRIPTION OF SYMBOLS 1 Caster 4 Bracket 5 Fork 6 Wheel 7 Oscillating shaft 9 Axle 11 Oscillating member 11c Front collision plate 11b Rear collision plate 12 Front stopper 14 Guide groove 14a Start end surface 14b End surface 15 Rear stopper 19 First urging member 22 Second biasing member

Claims (4)

A bracket attached to the vehicle body; a fork that pivotally supports the wheel axle; and a swing shaft that pivotally supports the fork on the bracket; and the swing shaft swingably pivotally supported to have a restricting means for restricting the swinging of the fork the axle from the starting position to the end position within a predetermined load range during light load, pivotably to the pivot shaft The swing member is provided on the bracket, and is provided with a swing member that starts swinging together with the fork from the end point position of the axle by the axle when the load exceeds the predetermined load range. A stopper that restricts the swinging of the swinging member from the swinging start position to the swinging stop position when a part of the swinging member collides , operates with a load within the predetermined load range, and moves the axle to the start position side. biased in, between the fork and the oscillating member A first biasing member which is interposed, working against a load exceeding the predetermined load range, biases the swing start position side of the swinging member swing member with fork, swinging A shock-absorbing caster, wherein a second urging member interposed between the member and the bracket is provided. The restricting means is a substantially arcuate guide groove formed on the swinging member and extending in the same direction as the swinging direction of the fork with the swinging shaft as the center, and the axle is fitted into the guide groove, 2. The shock absorber according to claim 1, further comprising a start end face on which the axle is abutted when the axle is at a start position and a terminal face on which the axle is abutted when the axle is at an end position.   3. The shock absorber according to claim 1, wherein the first urging member is a tension spring interposed between the fork and the swing member.   4. A shock absorber according to claim 1, wherein the second urging member is a push spring interposed between the swinging member and the bracket.

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