JP7245965B2 - rolling swivel caster - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling swivel caster that is reversibly attached to the lower part of a carriage, boston bag, or the like, and has improved drive followability.

A swivel caster is a wheel that freely swivels around an axis at a specified angle with respect to the wheel axis at the bottom of a truck or the like. It has the function of turning the wheel shaft in the driving direction to move the bogie smoothly. A normal swivel caster consists of a caster base with a swivel axis that is perpendicular to the road surface, a swivel member provided under the base that can swivel, and wheels attached to the swivel member, and the swivel axis and axle are the same. It is not on a flat surface, but a trail of a predetermined length is formed. When a driving force is applied in the direction of travel, the wheels turn in the direction of travel with the turning member due to the self-aligning torque due to the road surface resistance of the wheels to follow the steering. It has a structure that

In the conventional swivel caster, since the driving force in the direction of travel is a method of swiveling by the road surface resistance of the wheels, the swivel in the direction of travel depends on the angle formed by the direction of the wheels and the driving direction. Therefore, the magnitude of the generated resistance is not constant. Therefore, a situation arises in which the resistance force differs depending on the direction in which the trolley using casters is driven. Therefore, when the course is changed, the direction of travel is reversed from the rolling direction of the wheels up to that point, or when the direction is changed significantly, the truck may not move in the driving direction even if a driving force is applied to the truck. For example, the behavior of the trolley had to be increased in order to change the course, and there were phenomena that made it difficult to move smoothly.

In addition, since a dolly is usually equipped with multiple swivel casters, if each caster is oriented randomly, each caster will generate a different resistance force. Under such circumstances, when trying to change the course of the bogie in the desired direction, if the driving force is weak, complex behavioral manipulation of the bogie that depends on the grounding condition of the wheels is required, and the bogie can smoothly move in the direction of the changed course. The original function of the swivel caster to move it can no longer be fulfilled. In particular, there is a problem that this problem becomes conspicuous when transporting heavy objects or when road conditions are poor.

In order to solve the technical problems of the swivel caster as described above, the following improvement techniques have been developed.
In the preceding case 1, a turning member is rotatably supported by a support frame via a rolling element, and a wheel is rotatably supported by the turning member, and the center line of the turning member and the grounding point of the wheel are aligned. A swivel caster having a trail between them is characterized in that a trail reversing mechanism is provided between a swivel member and a wheel (Japanese Utility Model Laid-Open No. 61-115704). In this invention, the wheels are reversed by the action of the reversing mechanism of the trail when the course of the truck is changed, and it is possible to suppress the large movement of the truck accompanying turning. In the preceding case 1, a second shaft was introduced as a mechanism to realize the behavior in which the wheels reversed 180 degrees due to the back and forth movement of the caster with a small amount of movement, and the introduced mechanism reversed the trail instead of the wheels. It is characterized by the presence of However, in this invention, the point where the extension line of the turning center line of the wheel supported by the second bearing touches the road surface is behind the grounding point of the wheel with respect to the traveling direction A, so the wheel follows when changing course. However, there is a drawback that the steering resistance of the wheels is increased and the wear of the tires is increased.

Prior example 2 relates to a swivel caster in which a swivel member is rotatably supported by a first shaft fixed to the support frame, and an extension extending to the side of the swivel member is formed. A second shaft having a turning center line that intersects with the turning center line of the first shaft is provided, an axle is rotatably supported at the lower end of the second shaft, and a grounding point of the axle This swivel caster is characterized in that the swivel center line of the second shaft body is set so as to lie in the traveling direction of the vehicle body (Japanese Patent Laid-Open No. 4-87801).

The prior example 2 is an improvement of the prior example 1, and the inclination of the second axle with respect to the direction of travel is opposite to that of the prior example 1 to form a trailing state. . It is said that by forming such a trail state, a stable follow-up operation of the wheels can be obtained. However, when pursuing the relationship between the formation of such a trail and the wheels, the preceding cases 2 and 1 show the following: Similar drawbacks inevitably arise in relation to trail conditions and wheels. The basic principle of operation is that the rotation axis of the wheel of the swivel caster is parallel to the road surface. is not parallel to the road surface and is slanted. Therefore, if the inclination direction (trail) of the second shaft toward the driving direction and the direction of travel of the wheels are different, the followability of the wheels is deteriorated, and the trail and the travel direction of the wheels are perpendicular to each other. When it becomes , there is a drawback that the moment to turn is no longer generated and the caster falls into a stuck state that makes it difficult to escape.

Prior example 3 is used in driver's carts, wheelchairs, and hand-held mobility devices with wheels. The cam 15 is equipped with a protrusion on the outer periphery that makes it difficult to ride on in the opposite direction in order to prevent "rolling over" by suppressing turning. is provided on the mounting base 1 so as to suppress its rotation within a predetermined angle, and a follower 16 is provided on the yoke 12 and biased by a push spring 17 so as to abut on the cam 15. The follower 16 once overcomes the wheel This is an invention in which the phase of the protrusion and the angle of rotation limit are set so that it is in a state in which it tries to run over again in the opposite direction (Japanese Patent Application Laid-Open No. 2002-293108).

The preceding example 3 is a device for controlling the rotation of a caster to restrict turning, but on a left-right sloping road surface, the wheel arbitrarily turns to the bottom of the slope due to the influence of gravity, causing the wheelbarrow to drift sideways. It is intended to prevent the defect that causes the phenomenon that the On the other hand, in the present invention, when the wheel support portion is turned by the load of the driving force in the traveling direction of the wheelbarrow (caster base), a return torque is generated in the two-wheel support portion, and the wheel support portion is turned. It is a technical idea that has a mechanism, and its purpose, configuration, and effect are completely different.

Prior Case 4 discloses a movable caster as follows. The caster comprises a first swivel shaft (110) mounted on a caster base (101) that can move its position, a swivel member (150) capable of rotating the swivel shaft with one simple operation, and the swivel member. A wheel support (160) whose upper part is coupled so that (150) can be rotated to another position on a second rotating shaft (120), and a wheel (170) attached to the lower part of the wheel support (160) It is described as consisting of (U.S. Patent Application No. 2011/0232028)

In Prior Case 4, the constituent members seem to be common to some of the constituent members of the present invention, but the operation principle and configuration of the mechanism that can freely change the traveling direction of the caster by combining them are different from the present invention. is fundamentally different from
First, in the preceding case 4, the second rotating shaft (120) is rotatable, and the wheel support and the wheel support part and the wheel can be freely turned by changing the direction of the driving force. There was a problem that the wheels were swung around. On the other hand, in the present invention, since the corresponding second shaft body (5) does not rotate, a mechanism for tilting the axle when the direction of the driving force is changed is used to turn the wheels to follow the steering. That is, both of them are completely different in the principle of operation for turning the wheels in the changed direction to follow the steering when the direction of the driving force with respect to the traveling direction of the caster is changed, as well as in the configuration and operation mechanism for that purpose. Therefore, in the present invention, the wheel supporting portion and the wheel cannot be swung around, and in Prior Case 4, when the direction of the driving force is changed vertically, the caster is prevented from being stuck in a difficult-to-escape state. can't
Secondly, the present invention has the setting of trails t1 and t2 from the wheel grounding point C, so that the vertical distance between the reference plane of the supporting caster base and the wheel grounding point is always constant, and the movement of the caster is always constant. It has the advantage of being smoother. However, prior example 4 does not have trail t1 or trail t2, and does not have the advantage of resolving the stuck state where the motor does not move when the direction of travel of the driving force suddenly changes to the vertical direction.
The third is that while the direction of movement of the caster when the driving force is applied in Prior Case 4 is in front of the second rotating shaft (120) to which the wheel support portion (160) is coupled, the driving force of the present invention is The direction of travel under load is completely opposite to the front of the wheels. Therefore, in the prior example 4, the trail t1 and the trail t2 cannot be set in the same direction as in the present invention, and the vertical distance between the reference plane of the supporting caster base and the wheel contact point cannot be made constant.
Fourthly, the present invention is provided with a turning return mechanism for the wheel support portion, whereas the prior example 4 does not have a turning return mechanism for the wheel support portion, and the caster becomes stuck in a state that makes it difficult to escape. cannot be prevented.
As described above, the configuration and mechanism of the present invention and Prior Case 4 are significantly different. 4 has the drawback that the problem to be solved by the present invention cannot be solved at all.

Japanese Utility Model Laid-Open No. 61-115704 (Previous Case 1) Japanese Patent Application Laid-Open No. 4-87801 (Preceding Case 2) Japanese Patent Application Laid-Open No. 2002-293108 (Prior Case 3) US Patent Application No. 2011/0232028 (Previous Case 4)

In a normal swivel caster, the magnitude of the resistance generated is not constant depending on the angle formed by the direction of the wheels and the driving direction. For this reason, a truck using casters has a situation where the resistance varies depending on the driving direction. If the rolling direction of the wheels and the driving direction are not the same, the truck will not move in the driving direction. Also, since multiple casters are usually installed, if each caster is oriented randomly, each caster will generate a different resistance. Under such circumstances, if the power to drive the truck is weak, it is necessary to operate the truck depending on the grounding condition of the wheels, and the original function of the swivel caster to move the truck smoothly in the driven direction cannot be fulfilled. put away. Remedies have been developed in the past in an attempt to overcome the drawbacks of such swivel casters, but have been unsatisfactory. Therefore, in the present invention, the above problem is solved by a method different in principle from the conventional improvement measures.

In order to solve the above-mentioned problems, the wheels of the caster that follow the steering by the trail are constructed so as to form a perfect two-degree-of-freedom rolling pair, and the wheels operate with a perfect two-degree-of-freedom rolling pair. The main feature is that the tread shape of the wheel is configured so that the vertical distance between the caster base and the wheel contact point is geometrically unique and constant.

In order to solve the above problems, the present invention first studied the mechanism of the movement resistance of the swivel caster as follows.

As described above, the conventional swivel caster generates an inconsistent amount of resistance depending on the angle between the direction of the wheel and the driving direction. Therefore, a truck using casters has different resistance depending on the driving direction, and if the rolling direction of the wheels and the driving direction are not the same, the truck will not move in the driving direction. In most cases, the carriage does not move in the driving direction in this way when a driving force is applied to change the course of the carriage. SUMMARY OF THE INVENTION The present invention is intended to solve the problems caused by such characteristics of swivel casters. Therefore, in order to solve the difficulties of the conventional swivel caster, it is necessary to accurately understand its technical principle.

As shown in FIG. 11, the forms of action of the resistance force at the wheel contact point C of the conventional swivel caster D can be classified into three types. In the first mode of action, the driving force acts perpendicularly to the rolling direction of the wheel, and the driving phase angle between the driving direction and the rolling direction of the wheel is 90 degrees (FIG. 11(a)). In this case, all of the driving force acts as turning force, and the ground contact points of the wheels do not move. Since there is no component in the rolling direction of the driving force, the wheel is stationary and the maximum turning resistance is generated. However, this action occurs only when the rolling direction of the wheel and the driving direction are at right angles.

In the second mode of action, the driving phase angle is less than 90 degrees, and the wheel changes direction due to the turning component of the driving force while rolling due to the rolling component of the driving force (Fig. 11(b)).

In the third mode of action, the direction of the driving force coincides with the rolling direction of the wheel, and the driving phase angle is 0 degrees, as shown in FIG. 11(c). In this case, no turning force is generated and the truck moves in the driving direction with the rolling resistance of the wheels.
When the truck is driven with the first working mode as the starting mode, it immediately shifts to the second working mode, and if it continues to drive in the same direction, it finally shifts to the third working mode. When the relationship of the steering follow-up of the wheels at that time is shown, as shown in FIG.

From the mechanism of the motion resistance of the conventional swivel caster D, the maximum swivel resistance torque of the ordinary swivel caster occurs when the direction is changed while the wheels are stationary. This occurs when the drive phase angle is 90 degrees, but in this state the horizontal distance between the grounding point and the pivot axis is maximum, so the resistance is not maximum. The maximum resistance to the driving force occurs when the driving phase angle is approximately 45 degrees. The reason why the turning resistance is generated by the driving force is that the contact portion of the wheel is actually a surface rather than a point. Even if the grounding part of the wheel is a surface, if it is a rolling movement, it will not create a large resistance force, but if the wheel is turned while the axle is held horizontally, the wheel will slide on the grounding surface even if it is rolling. is generated and becomes turning resistance.

Therefore, an ideal swivel caster should have the same rolling characteristics in all directions on the road surface. This is because if the wheel is spherical, it can have the same rolling characteristics in any direction on the road surface. In addition, swivel casters are required to have wheels with a simple and strong structure, in addition to having the function of moving in all directions as a product characteristic. For this reason, spherical wheels meeting the above conditions have rarely been used for swivel casters.

As described above, an ideal swivel caster is required to have the same rolling characteristics in all directions on the road surface.
A wheel with an axis of rotational symmetry and a spherical surface has a so-called doughnut-shaped surface. The donut-shaped surface shape is called a torus. When the torus is viewed from the direction of the axis of rotational symmetry, it is a double concentric circle consisting of the donut hole circle and the outer shape circle, and the circle forming these double concentric circles corresponds to the core of the donut. The circle is called the torus great circle. The torus also has a circular cross-sectional shape in the axial direction, which is called a torus small circle.

When such a torus is regarded as a wheel, the rotational symmetry axis of the torus is the axle of the wheel, and the torus surface can be regarded as the tread of the wheel. The situation in which the wheel contacts the road surface and rotates and rolls around the axle can be interpreted as the action of the tread contacting the road surface and rolling in the circumferential direction of the great circle of the torus. This is the rolling motion of a normal wheel. However, if the shape of the torus surface is the tread of a wheel, it is possible to roll in the circumferential direction of a large circle and at the same time to roll in the direction of a small circle perpendicular thereto. The axle tilts as the small circle rolls in the circumferential direction. If rolling motion in two directions can be performed in this manner, the rolling motion can occur within a certain range if the wheel has an arc-shaped contact surface such as a sphere or a torus. Therefore, if a wheel having an arc-shaped contact surface such as a sphere or a torus is used in the present invention, and a mechanism for tilting the axle is incorporated, the wheel can roll in the direction of a large circle and roll in a small circle. Rolling motion in the circumferential direction can be performed at the same time.

Thus, in order to be able to roll in the circumferential direction of a large circle in a torus-shaped wheel and at the same time to be able to roll in the circumferential direction of a small circle perpendicular to it, the axle of the large circle must be placed in the second direction. 1 axle and a small circle axle as the second axle. Specifically, the second axle is parallel to the road surface and orthogonal to the first axle, and the second axle is vertically offset from the first axle by the radius of a great circle. FIG. 12(a).
As shown in FIG. Directional rolling motion and minor circumferential rolling motion can be maintained. However, if the tread remains toroidal, rotation about the second axle will slightly change the vertical distance between the caster base and the wheel contact point.

However, since swivel casters are required to move the carriage horizontally, even rolling swivel casters are required to have a constant vertical distance between the caster base and the wheel contact point. Therefore, in order to obtain a tread shape that satisfies the requirement that the vertical distance between the caster base of the swivel caster and the wheel grounding point is constant, a geometric drawing from the inclination angle of the second axle, the offset, and the radius of the wheel, or By uniquely determining by geometric calculation, the second axis can be arbitrarily set within the range that satisfies the condition of a constant vertical distance that is allowed as a swivel caster. In addition, it is also possible to determine the offset, wheel radius, wheel width, etc. in consideration of the behavior stability of the swivel caster.

Based on the above research on the mechanism of motion resistance of swivel casters and the basic rolling motion of the wheels, swivel casters also use wheels with arc-shaped contact surfaces such as spherical or torus-shaped wheels, and their axles are It has been found that if a tilting mechanism is incorporated, the direction of the wheel can be changed only by rolling motion without slippage.

Based on the principle and technical idea as described above, the present invention has the following configuration as means for solving the problems.

The present invention comprises a caster base having a first swivel shaft 2 perpendicular to the road surface, and a swivel member rotatably attached to the first swivel shaft 2. The turning member extends laterally from the shaft mounting portion and forms an extended turning portion whose rear portion is bent downward into a "<" shape. A second shaft having a turning center line that intersects with the turning center line of the shaft is mounted, a wheel support is mounted on the lower part of the second shaft, and a lower end of the wheel support is parallel to the road surface. An axle is provided, and a wheel having a spherical or arcuate contact surface is rotatably mounted on the axle. A trail is thereby formed between the pivot centerline of the pivot member mounted on the first vertical pivot axis and the ground contact point of the wheel. When a driving force is applied to the caster base in order to change the course of the truck in an arbitrary direction, even if the traveling direction of the trail and the wheels are greatly different or perpendicular to each other, the spherical or circular A wheel with an arc-shaped contact surface turns into a turning moment and rolls in the lateral direction, reducing the turning starting force in the direction of changing the course of the turning caster and improving the turning characteristics of the wheel. A rolling swivel caster characterized by:

As described above, the rolling and turning caster according to the present invention firstly uses a wheel having an arc-shaped contact surface such as a sphere or a torus, and secondly, a new mechanism for tilting the axle. , and the horizontally fixed axle is tilted so that the wheels can also roll in the lateral direction. The features of the rolling and turning caster according to the present invention will be described in detail below.

The present invention is a swivel of an ordinary caster which consists of a caster base with a swivel axis perpendicular to the road surface, a swivel member provided therebelow, and a wheel attached to the swivel member and having an axle parallel to the road surface. The first feature of the member is that the following mechanism for tilting the axle is newly provided.

A mechanism for tilting an axle according to the present invention includes a caster base having a first swivel shaft perpendicular to a road surface, and a swivel member rotatably attached to a lower portion of the first perpendicular swivel shaft. The swivel member extends laterally from its pivoting portion and forms an extended swivel portion whose rear portion is bent downward in a doglegged shape. A second shaft is attached to the extended turning portion, and the second shaft is inclined with respect to the first turning shaft and intersects the turning center line MM of the first turning shaft. It is set and mounted so as to have a wheel support turning centerline NN. Further, a wheel support part is attached to the lower part of the second shaft body, and an axle parallel to the road surface is provided at the lower end of the wheel support part, and the axle has an arc-shaped ground contact surface such as a spherical shape or a torus shape. Attach the wheel you have so that it can rotate freely. Moreover, a trail is formed between the turning center line MM of the turning member 3 mounted on the vertical first turning shaft 2 and the contact point C of the wheel.

The mechanism for tilting the axle is configured as described above, so that even if the second shaft is tilted and the traveling direction of the wheel is perpendicular to the trail, the wheel rolls in the lateral direction. Thus, it becomes a rolling and turning caster that improves the characteristics of turning in the direction of travel.

A second feature of the present invention is that the wheel has an arcuate contact surface such as a sphere or a torus. Even if a driving force is applied to the chassis and the wheels tilt, the wheels roll in the lateral direction while contacting the road surface, keeping the tilted axle horizontal and turning the wheels in the direction of travel.

As described above, according to the present invention, the caster base is equipped with a first pivot shaft perpendicular to the road surface, the first perpendicular pivot shaft extends laterally from the pivot attachment portion, and has a rear portion thereof. A swivel member formed by forming an extended swivel portion bent downward in a letter V shape is rotatably attached to the shaft, and a downwardly inclined second shaft is attached to the extended swivel portion of the swivel member. A wheel support portion is attached to the lower portion of the second shaft body, and an axle parallel to the road surface is provided at the lower end of the wheel support portion. A rolling swivel caster in which a wheel having an arcuate contact surface is rotatably mounted, wherein the first swivel axis is perpendicular to the road surface and has a swivel center line M-M of the first swivel axis. , the second shaft is inclined with respect to the first turning axis perpendicular to the road surface and has a turning center line NN that intersects the turning center line MM of the first turning axis; The first pivot axis is set and mounted so as to form a trail t1 between the intersection point A1 of the turning centerline MM perpendicular to the road surface and the road surface A1 and the wheel contact point C. At the same time, the second shaft body is set and mounted so that a trail t2 is formed between the intersection A2 of the turning center line NN of the wheel support portion with the road surface and the ground contact point C of the wheel, and further the wheel ground contact point C The vertical distance between the reference surface of the support caster base and the wheel grounding point is always constant by setting the trail t1 direction and the trail t2 direction so that they are formed in the same direction when viewed from above. be. In addition, when a driving force is applied to the caster base in an arbitrary direction, the wheels are towed in the driving direction and followed by turning, and the course of the applied driving force changes to follow the trail. When a load is applied in a direction perpendicular to the direction of travel of the wheel, the axle of the wheel, which has an arc-shaped contact surface such as a sphere or a torus, is tilted by the load, causing the wheel to roll sideways and move in the vertical direction. This rolling and turning caster is characterized in that it turns to follow a rolling snake.

A rolling swivel caster according to the present invention comprises a caster base having a first swivel axis perpendicular to the road surface, a swivel member rotatably mounted thereunder, a wheel support attached to the swivel member, and a lower end thereof. is provided with an axle, and the axle is composed of wheels with an arc-shaped ground contact surface such as a spherical or torus shape. When a driving force is applied in the direction of travel, the axle tilts, and the wheels turn while rolling in the direction of travel together with the turning member due to the self-aligning torque generated by the road surface resistance of the wheels. It has a structure that follows the rudder.

In this way, the present invention adopts a two-axis system of the first turning shaft and the second axle, and the turning center lines of both of them intersect to form a trail of a predetermined length between the grounding points of the wheels. Since the wheels are provided with a mechanism for tilting the wheels, and the wheels have an arc-shaped contact surface such as a spherical shape or a torus shape, driving force is applied to change the course, and the trail and the wheels advance. Even if the direction is perpendicular to the direction, the wheel with a spherical or arc-shaped ground contact surface tilts and rolls sideways while contacting the road surface, so it is possible to easily start turning in the course change direction. be.

In addition, even if the turning caster according to the present invention is to change course in any direction in all directions, the driving force applied to the wheel becomes a turning moment and turns while rolling the wheel, so the wheel can be easily moved. can be made to follow the steering in the direction of travel.

BRIEF DESCRIPTION OF THE DRAWINGS It is a two-side view of one Example which shows the basic structure of the rolling turning caster which concerns on this invention, (A) is the side view, (B) is a front view. It is a two-sided view of the second embodiment showing the basic structure of the rolling and turning caster according to the present invention, (a) is its side view, and (b) is a front view. It is a two-sided view of the 3rd other Example which shows the basic structure of the rolling turning caster which concerns on this invention, (A) is the side view, (B) is a front view. Fig. 10 is a two-sided view showing the behavior of the rolling and turning caster according to the present invention at the angle formed by the direction of the driving force applied to the rolling and turning caster and the direction of the turning member 3; and (b) is a perspective view when the angle is a right angle. When the rolling and turning caster according to the present invention is loaded with a driving force to change the course and the traveling direction of the wheel becomes perpendicular to the trail, the wheel having a spherical or arc-shaped contact surface tilts. It is a trihedral view showing operation states (A), (B), and (C) in which the vehicle rolls in the lateral direction while contacting the road surface and easily starts turning in the course change direction, and (A) is driven for course change. (b) is a perspective view showing a state where the force is perpendicular to the trail and the traveling direction of the wheel; ) is a perspective view showing a state in which the vehicle rolls and turns, and the driving force is aligned with the advancing direction of the trail and the wheels. FIG. 4 is a geometrical diagram showing the motion of a wheel turning around the second shaft 5; FIG. 4 is a side view showing the rolling and swiveling caster temporarily stuck in a state in which the first and second trails formed on the rolling and swiveling caster are oriented in the same direction. (A) and (B) are front views of the wheel with the main parts sectioned showing the tread shape of the spherical wheel in axial longitudinal section, and (C) is a wheel (B) with the axle tilt angle limited to within a specified angle. It is a front view which shows the state which is. FIG. 4 is an explanatory view showing a turning return mechanism of a wheel support portion provided between a wheel support portion shaft protruding from the back surface of the turning member and a turning member main body; A rear view showing an embodiment of the turning return mechanism, (B) is the turning of the wheel support when the arc-shaped spring is deformed by the turning of the wheel support, and the return torque is generated in proportion to the turning angle of the wheel support. Rear view showing an embodiment of the return mechanism, (C) is a rear view showing another embodiment of the turning return mechanism of the wheel support attached to the back of the turning member, (D) and (E) are the wheel support. FIG. 10 is a rear view showing another embodiment of the turning return mechanism for the wheel support portion when the circular arc spring is deformed by the rotation of the cam and the return torque corresponding to the turning angle of the wheel support portion is generated. FIG. 10 is a side view showing an embodiment of a rolling and turning caster having a direction changing mechanism that does not allow the turning shaft to swing. FIG. 10 is an explanatory drawing showing a normal swivel caster and the mode of action of the resistance force at the wheel grounding point thereof; (a) and (b) are explanatory diagrams showing that the second axle is positioned at a low offset position, and the second axle is configured at an installation angle that is inclined with respect to the road surface.

Hereinafter, a form for implementing a rolling and turning caster according to the present invention will be described.

First, the basic structure of the rolling and turning caster according to the present invention will be described.
FIG. 1 is a two-sided view showing an embodiment of a rolling and turning caster, where (a) is its side view and (b) is its front view.
In FIG. 1, a caster base 1 is a member for fixing a caster to a trolley, Boston bag, etc. A first turning shaft 2 perpendicular to the road surface A is mounted on the caster base 1, and the first turning shaft 2 is mounted on the caster base 1. A turning member 3 is rotatably attached to the shaft 2 . The swivel member 3 extends laterally from its shaft mounting portion and forms an extended swivel portion 4 whose rear portion is bent downward into a "<" shape. A second shaft body 5 having a turning center line N--N intersecting with the turning center line M--M of the first turning shaft 2 is attached to the extension turning part 4, and a wheel support part 6 is freely rotatable under the second shaft body 5. is attached to the At that time, the second shaft body 5 is inclined with respect to the first turning shaft 2, and both are set to intersect each other. Further, a wheel support portion 6 is attached to the lower portion of the extension turning portion 4, and an axle 7 parallel to the road surface is provided at the lower end portion of the wheel support portion 6, and the axle 7 has a spherical shape. Alternatively, a wheel 8 having an arcuate contact surface is rotatably mounted.

In FIG. 1, the first turning shaft 2 is perpendicular to the road surface A, and the trail t1 is between the intersection A1 of the turning center line MM of the first turning shaft 2 with the road surface and the wheel contact point C. At the same time, the second shaft body 5 is set so that a trail t2 is formed between the intersection A2 of the turning center line NN of the wheel support portion 6 with the road surface and the contact point C of the wheel 8. .

Further, as the basic structure of the rolling and turning caster according to the present invention, the fact that the vertical distance between the reference plane B of the caster base 1 and the wheel contact point C is constant will be described.
In FIG. 1 showing an embodiment of the rolling and turning caster according to the present invention, the vertical distance between the reference plane B of the caster base 1 and the wheel contact point C depends on the direction of the turning member 3, the mounting angle of the wheel support 6, and the wheel support. It must always be constant without depending on the turning angle of the portion 6 . The relationship between the wheel radius, the mounting angle of the wheel support portion to the second shaft 5, and the tread shape in order to satisfy the fact that the vertical distance between the reference plane B of the caster base 1 and the wheel grounding point C is constant. etc. are determined by geometric uniqueness. In order to satisfy the fact that the vertical distance is constant, the relationship between the wheel radius, the mounting angle of the second shaft body 5 of the wheel supporting portion, and the tread shape is geometrically determined uniquely.

2 (a) side view and (b) front view showing the second embodiment of the rolling and turning caster according to the present invention, and FIG. 3 (a) side view and (b) showing the third embodiment. Also in the front view, the vertical distance between the reference plane B of the caster base 1 and the wheel contact point C must be constant. In order to satisfy such a constant vertical distance, the relationship between the wheel radius, the axle offset f, the mounting angle of the second shaft body 5 of the wheel support portion, and the tread shape must be geometrically uniquely determined. determined by The first turning shaft 2 is perpendicular to the road surface A, and a trail t1 is formed between the intersection point A1 of the first turning shaft 2 with the road surface and the wheel contact point C. A trail t2 is formed between the intersection point A2 of the turning center line NN of the portion 6 with the road surface and the contact point C of the wheel 8.

6A and 6B are geometric diagrams showing the motion of the wheel 8 turning around the second shaft 5. FIG. Symbol P0 in the figure is the center position of the wheel 8, P1 is the lowest position of the wheel torus great circle, P2 is the leg of the perpendicular drawn from P1 to the road surface, and f is the offset amount of the second shaft 5. In the figure, θ1 is the angle between the second axle and the road surface, θ2 is the turning angle of the second axle, and θ3 is the turning angle of the torus great circle of the wheel 8 when the great circle is closest to the road surface. An angle .theta.4 representing the direction of a point on the circumference of the great circle represents the deflection angle of the contact point viewed from the plane of the great circle. If the tread surface is located at a distance Z from the circumference of the great circle in a direction slanted at an angle θ4 from the circumference of the great circle, the vertical distance is constant.

The tread shape that keeps the vertical distance constant is called the basic tread shape. Under the condition that the vertical distance is constant, when the axle offset is zero (0), the basic tread shape becomes spherical as shown in FIG. . When the axle 7 is positioned above the second shaft body 5 of the wheel support portion by the offset f, the wheel 8 has a vertically oblong spherical shape as shown in FIG. Conversely, when the axle 7 is positioned below the second shaft body 5 of the wheel support portion due to the offset f, the wheel 8 has a barrel shape as shown in FIG.

Next, FIG. 4 is a two-sided view showing the behavior of the swivel caster at the angle formed by the direction of the driving force K1 applied to the rolling swivel caster according to the present invention and the direction L of the swivel member 3. FIG. (b) is a perspective view when the angle is smaller than 90 degrees, and FIG. 4 (a) is a perspective view when the angle is a right angle.

In FIG. 4B, the angle formed by the direction of the driving force K1 and the direction of the turning member 3 is defined as turning phase angle θ5, and the angle formed between the turning member 3 and the wheel support portion 6 is defined as the wheel support portion turning angle θ6. . The turning member 3 has the negative Y direction as the positive direction. In the above configuration, when a driving force in the K1 direction is applied to the caster base 1 as shown in FIG. 4(a), the turning phase angle .theta.5 is 90 degrees and the wheel support portion turning angle .theta.6 is 0 degrees. In this state, the grounding point C generates a resistance K2 in the negative direction. The driving force K1 and the resistance force K2 form a force couple, and this force couple generates a torque T1 for turning the turning member 3 around the turning shaft 2. As shown in FIG. At the same time, a torque T2 is generated around the second shaft body 5 of the wheel support portion to rotate the wheel support portion 6 .

In (a), (b), and (c) of FIG. 5, the driving force K1 is applied to the caster base 1 of the rolling and turning caster according to the present invention to change the course so that the trail and the traveling direction of the wheels 8 are perpendicular to each other. In this case, the axle 7 is tilted, and the wheel 8 having a spherical or arc-shaped contact surface rolls in the lateral direction while contacting the road surface A, and the vehicle easily starts turning in the course change direction. 3 is a three-sided perspective view shown; FIG. (a) is a perspective view when the direction of travel of the wheels 8 is perpendicular to the trail due to the course change, and the wheels 8 follow the driving force K1 around the axle. begin to rotate. (b) is a perspective view showing a state in which the wheel 8 is tilted and rolls in the lateral direction while contacting the road surface A. Decrease. (C) is a perspective view showing a state in which the driving force is aligned with the traveling direction of the trail and the wheels 8 after further rolling. As a result, the wheel support portion turning angle θ6 decreases. Further, when the driving is continued, the turning phase angle θ5 finally converges to 0 degrees, and the wheel support portion turning angle θ6 also converges to 0 degrees.

Next, a description will be given of a trail configuration that prevents rolling and turning casters from being stuck.
When the rolling and turning caster is also driven in the direction of the driving force K1, when the turning phase angle θ5 is 0 degrees and the wheel support portion turning angle θ6 is 90 degrees, the wheels cannot be rotated by the driving force K1, and the wheel support Since no torque is generated to turn the portion 6, the vehicle pushes the side wheel and temporarily falls into a stuck state. However, at that time, if the directions of the first trail t1 and the second trail t2 formed on the rolling and turning caster are the same, the singular point becomes unstable, and even a slight change in the driving force Equilibrium is broken and the stuck state can be escaped (Fig. 7). Therefore, when manufacturing a rolling and turning caster, the direction of the first trail t1 and the direction of the second trail t2 are designed to be the same.

Next, an example of tread shape optimization in a rolling swivel caster will be described.
8(a) and 8(b) are front views of the wheel 8, showing the tread shape in axial longitudinal section of the spherical wheel, with the essential parts sectioned. In the case of FIG. 8(a), since the wheel 8 is spherical, the cross-sectional shape is a substantially perfect circular arc. In the case of such a shape, the force for returning the wheels in the driving direction is weak.
Therefore, in order to obtain straight running stability, the degree of freedom of the wheel should be limited to 1 when the yoke inclination angle is near 0 degrees. By varying the curvature of the dreads in the longitudinal axial direction, straight line stability can be adjusted.
Also, by making the tread near the end of the shaft conical as shown in FIG. A torus-shaped or barrel-shaped wheel can also be applied.

Next, in order to generate a turning return force of the wheel support portion 6 without changing the tread shape, when the wheel support portion 6 turns and a turning displacement occurs between the wheel support portion 6 and the revolving member 3, , a torque that tends to reduce this displacement should be generated. For this reason, an embodiment may be provided in which a mechanism is provided to generate a turning restoring force of the wheel support portion by means of a spring. An embodiment provided with a turning return mechanism for the wheel support portion 6 will be described below.

FIG. 9 is an explanatory side view showing an embodiment of the pivoting return mechanism of the wheel support portion 6 provided between the protruding second shaft 5 of the wheel support portion 6 and the turning member 3. As shown in FIG.
In one embodiment of the turning return mechanism, as shown in FIGS. , a fan-shaped projecting portion 10 is provided on the head of the second shaft body 5 projecting from the back surface of the turning member 3, and a stopper 11 is provided on the back surface of the turning member 3 for restricting the rotation range of the fan-shaped projecting portion 10, An arc-shaped spring 12 is attached by a pin 9 between the fan-shaped projecting portion 10 and the stopper 11, and when the stopper 11 and the fan-shaped projecting portion 10 come into contact with each other, the turning angle of the wheel support portion 6 is limited. configured to give When the circular spring 12 is deformed by the pivoting of the wheel supporting portion 6, a restoring torque is generated in proportion to the pivoting angle of the wheel supporting portion 6. As shown in FIG. As an embodiment of the swivel caster according to the present invention, a turning return mechanism for the wheel support portion 6 configured as described above may be provided in the basic configuration.

Next, FIGS. 9(C), 9(D) and 9(E) show another embodiment in which a turning return mechanism is provided in the basic structure of the swivel caster according to the present invention. The configuration is such that the head portion of the second shaft body 5 attached to the extended turning portion 4 of the turning member 3 protrudes from the rear surface of the turning member 3, and the head portion of the second shaft body 5 protruding to the rear surface of the turning member 3 is provided with a cam 13 that defines its return torque characteristics, an arcuate spring 14 is attached to the back surface of the turning member 3, and a roller 15 that rolls on the cam surface is attached to the tip of the arcuate spring 14. , the cam 13 and the arcuate spring 14 contact each other to limit the turning angle of the wheel support portion 6 . Then, when the second shaft 5 of the wheel support portion 6 rotates due to the turning of the wheel 8, the rotation of the cam 13 pushes the roller 15 and deforms the arc-shaped spring 14 to correspond to the turning angle of the wheel support portion 6. This rolling and turning caster is characterized in that it is provided with a turning return mechanism for the wheel support portion 6 so as to generate a restored torque.

FIG. 10 is a side view of an embodiment of a rolling and swiveling caster with a turning mechanism that does not allow the swivel shaft to swing. In the rolling swivel caster having the basic structure of the present invention, the ground contact point of the swivel center line MM of the first swivel shaft 2 and the swivel center line of the wheel support portion 6 mounted on the inclined second shaft body 5 Even if the grounding point NN and the grounding point NN are formed to be the grounding intersection 16, and the turning member 3 is forced to turn, the first turning shaft 2 of the turning member 3 will not swing around the grounding intersection 16. The wheel 8 having an arc-shaped contact surface such as a sphere or a torus rolls to turn and smoothly change the direction of the wheel 8.例文帳に追加

In the case of a conventional caster, if a turning torque is applied to the turning member while a load is applied to the wheel to change the direction of the wheel, stationary steering occurs at the grounding point of the wheel and the reaction force of the turning torque occurs. , the action of swinging the turning shaft is generated.

However, in the case of the rolling swivel caster having a direction changing mechanism that does not swing the first swivel shaft 2 shown in FIG. The ground contact point C of the wheel 8 with a contact surface turns around the contact point 16 in a complete rolling motion as part of a conical surface with the intersection point 16 as its apex.

Further, since the ground contact point 16 of the first turning shaft 2 and the second shaft body 5 of the wheel support portion 6 is set on the road surface A, the turning movement of the turning member 3 does not cause the turning shaft 2 to swing. . In reality, the rolling resistance of the wheels 8 and the reaction force of the wheel support return mechanism act due to the load. It is possible to change the direction of the wheels with minimal effort.

REFERENCE SIGNS LIST 1 Caster base 2 First turning shaft 3 Turning member 4 Extension turning part 5 Second shaft body 6 Wheel supporting part 7 Axle 8 Wheel 9 Pin 10 Fan-shaped projecting part 11 Stopper 12 Circle Arc-shaped spring 13 Cam 14 Arc-shaped spring 15 Roller 16 Ground contact point A Road surface A1 Intersection point A2 of the first turning shaft with the road surface M-M First turning shaft Turning center line NN Turning center line of wheel support K1 Driving force K2 Resistance L Direction of turning member P0 Wheel center position,
P1: lowest position of wheel torus great circle,
P2 … The perpendicular leg that is lowered from P1 to the road surface,
T1: Torque for turning the turning member T2: Torque for turning the wheel support Z: Distance from the circumference of the great circle θ1: Angle between the second vehicle body and the road surface θ2: Turning angle of the second vehicle body ,
θ3: an angle representing the direction of a point on the circumference of a great circle,
θ4 .

Claims (3)

The caster base is equipped with a first pivot shaft that is perpendicular to the road surface. The first pivot shaft extends laterally from the pivot attachment portion, and the rear portion of the first pivot shaft is downwardly bent into a "<" shape. A swivel member forming a curved swivel extension is rotatably journalled, and a downwardly inclined second shaft is attached to the extended swivel portion of the swivel member, and a lower portion of the second shaft. A wheel support is attached to the wheel support, and an axle parallel to the road surface is provided at the lower end of the wheel support, and the axle has an arc-shaped ground contact surface such as a sphere or a torus. In a rolling swivel caster rotatably attached to a shaft,
the first pivot axis is perpendicular to the road surface and has a pivot centerline M-M of the first pivot axis;
The second shaft is inclined with respect to a first turning axis perpendicular to the road surface and has a turning center line NN that intersects the turning center line MM of the first turning axis. ,
The first turning axis is set and mounted so as to form a trail t1 between the road surface intersection A1 of the turning center line M-M perpendicular to the road surface and the wheel contact point C. The body is set and installed so that a trail t2 is formed between the intersection A2 of the turning center line NN of the wheel support portion with the road surface and the ground contact point C of the wheel, and further, when viewed from the wheel ground contact point C, the trail t2 is formed. By setting the t1 direction and the t2 direction of the trail to be formed in the same direction, the vertical distance between the reference surface of the supporting caster base and the wheel grounding point is always constant,
When a driving force is applied to the caster base in an arbitrary direction of travel, the wheels are pulled in the driving direction and followed by turning, and the course of the applied driving force changes to the direction of the trail t1. When a load is applied in the direction perpendicular to the trail t2 direction and the direction of travel of the wheel, the axle of the wheel, which has an arc-shaped contact surface such as a sphere or torus, is tilted by the load, causing the wheel to roll laterally. while turning in the vertical direction of movement to follow the rolling snake.
A rolling swivel caster characterized by: projecting the head portion of the second shaft attached to the extended turning portion of the turning member from the rear surface of the turning member;
A fan-shaped protrusion is provided on the head of the second shaft protruding from the back surface of the turning member,
A stopper is provided on the back of the turning member to regulate the rotation range of the fan-shaped projection,
An arc-shaped spring is mounted between the fan-shaped projecting portion and the stopper,
configured to limit the turning angle of the wheel support portion by contact between the stopper and the fan-shaped projecting portion;
2. A turning return mechanism for a wheel support is provided, wherein when the arc-shaped spring is deformed by the turning of the wheel support, a return torque is generated in proportion to the turning angle of the wheel support. Rolling swivel casters as described. projecting the head portion of the second shaft attached to the extended turning portion of the turning member from the rear surface of the turning member;
A cam is provided on the head of the second shaft protruding from the back surface of the turning member, and
A circular spring is attached to the back of the turning member,
A roller that rolls on the cam surface is attached to the tip of the arc-shaped spring,
configured to limit the turning angle of the wheel support portion by contact between the cam and the arc-shaped spring;
When the second shaft of the wheel support portion rotates due to the turning of the wheel, the rotation of the cam pushes the roller, deforms the arc-shaped spring, and generates a return torque corresponding to the turning angle of the wheel supporting portion. 2. The rolling and turning caster according to claim 1, further comprising a turning return mechanism for the wheel supporting portion.

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