JP2022145430A - caster and vehicle - Google Patents

Abstract

To provide a caster which enables reduction of a force needed for travelling over a step with a simple structure, and to provide a vehicle.SOLUTION: A caster 10 includes: a frame 20; a main wheel 30 which is supported so as to be rotatable around a main wheel axle Am which is horizontal to the frame 20; an auxiliary wheel 40 which is supported so as to be rotatable around an auxiliary wheel axle Aa, which is parallel to the main wheel axle Am, relative to the frame 20; a bracket 50 attached to a vehicle body 202; and a connection mechanism 70 which connects the frame 20 with the bracket 50 in a manner that these components can rotate around a horizontal connection axle Ac and slide within a predetermined moving range in a sliding direction Ls perpendicular to the connection axle Ac.SELECTED DRAWING: Figure 1

Description

The present invention relates to casters and vehicles.

Casters attached to vehicles such as walking aids, autonomous mobile robots, electric wheelchairs, self-propelled wheelchairs, silver cars, baby carts, and trolleys are not suitable for obstacles such as steps, unevenness, slopes, stairs, etc. Techniques for climbing over and ascending and descending are required.

For example, Patent Document 1 discloses a structure of a caster that, when a main wheel collides with a step, an auxiliary wheel provided in front of the main wheel descends and the shared load of the auxiliary wheel increases to overcome the step. ing. Further, in Patent Document 2, when an auxiliary wheel provided in front of the main wheel collides with a step, the main wheel retreats and rises, and a caster that overcomes the step by changing the contact angle of the main wheel with the step is disclosed. Further, Patent Document 3 discloses a structure of a wheelchair in which a direct-acting actuator having a caster at its tip extends in the vertical direction, and the wheelchair main body and main wheels rise vertically while maintaining a horizontal posture, thereby overcoming a step. there is Further, in Patent Document 4, a small-diameter auxiliary wheel provided in front of the main wheel so that the ground contact portion is located above is connected to the main wheel so as to be able to transmit power, and is reduced in torque compared to the main wheel. There is disclosed a truck structure that overcomes a step by means of the thrust of auxiliary wheels with an increased force.

JP 2019-099066 A JP 2006-007855 A Japanese Patent Application Laid-Open No. 2003-180757 JP 2010-195160 A

However, in the caster of Patent Document 1, the training wheels push the ground and lift the vehicle body itself when going over a step, that is, the training wheels bear the entire weight of the vehicle body, so it is difficult to apply to heavy vehicles such as wheelchairs. In addition, in the caster of Patent Document 1, the biasing force of the spring provided as a mechanism for generating a restoring force for returning to the original state acts as a force in the opposite direction to the step-walking direction. There is a problem of increased thrust.

In addition, the caster of Patent Document 2 also has a limit in reducing the thrust force required to walk over a step, and has a complicated mechanism, like the caster of Patent Document 1. In addition, the wheelchair of Patent Document 3 requires at least three linear motion actuators and a control function for controlling each linear motion actuator in order to move vertically while maintaining a horizontal posture, and the structure is complicated. be. In addition, in the truck of Patent Document 4, power is always transmitted to the auxiliary wheels even when traveling on flat ground, so energy for traveling is wasted.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a caster and a vehicle that have a simple structure and can reduce the force required to walk over a step.

A caster according to an aspect of the present invention includes a frame, a main wheel supported rotatably about a main wheel axle horizontal to the frame, and an auxiliary wheel parallel to the main wheel axle relative to the frame. an auxiliary wheel rotatably supported around an axle; a bracket attached to the vehicle body; a connection mechanism for slidably connecting over a range of motion.

The caster can be transformed between a state in which only the main wheels are in contact with the running surface and a state in which the main wheels and auxiliary wheels are in contact with the running surface by rotating the frame with respect to the brackets attached to the vehicle body. is. That is, the auxiliary wheels can be brought into contact with the upper running surface of the step while the main wheels are in contact with the lower running surface of the step. Further, in this state, by sliding the bracket attached to the vehicle body to the side where the auxiliary wheels are provided with respect to the frame, the shared load received from the vehicle body moves from the main wheel side to the auxiliary wheel side. As a result, it is possible to reduce the propulsive force required to walk over the step.

A caster according to an aspect of the present invention includes a direct acting actuator capable of driving the connection shaft in the sliding direction with respect to the frame. As a result, it is possible to assist the movement of the bracket to the side of the auxiliary wheel with respect to the frame, so that the propulsive force required to overcome the step can be further reduced.

In the caster according to one aspect of the present invention, when the connection shaft moves to the side where the auxiliary wheels are provided in the movement range, the auxiliary wheels come into contact with the running surface and the shared load of the vehicle body applied to the main wheels. decreases, the shared load of the vehicle body applied to the auxiliary wheels increases. As a result, it is possible to efficiently and effectively move the load necessary for stepping over the step, so that the main wheels can more easily climb over the step.

In the caster according to one aspect of the present invention, when the connection shaft is located at the end of the movement range on the side where the main wheels are provided with respect to the auxiliary wheels, the auxiliary wheels maintain a state in which they are lifted from the running surface. do. As a result, it is possible to run only on the main wheels during normal running on a running surface without steps.

In the caster according to one aspect of the present invention, the bracket has a stopper that restricts the rotation range of the frame in the direction in which the auxiliary wheel is lifted from the running surface. As a result, the frame does not rotate more than necessary, and unstable running due to excessive lifting of the frame can be avoided.

In the caster according to one aspect of the present invention, the connection mechanism includes a connection shaft member provided on the bracket and having the connection shaft as the center axis, and a connection shaft member formed on the frame, the connection shaft member rotating around the connection shaft. a slot rotatably and slidably connected in the sliding direction. As a result, the connection mechanism can be realized in a simple form, and the connection mechanism can simultaneously perform the sliding function and the rotating function of the frame and the bracket. In addition, the connecting shaft member and the elongated hole allow the bracket to slide smoothly with respect to the frame, enabling smooth load transfer as if sliding up a slope. Therefore, the thrust reduction effect can be obtained effectively and efficiently.

In the caster according to one aspect of the present invention, the elongated hole is inclined downward from the side of the auxiliary wheel toward the side of the main wheel when both the main wheel and the auxiliary wheel are in contact with the ground on the same plane. provided to do so. Thus, in a state in which both the main wheels and the auxiliary wheels are in contact with the ground on the same plane, the elongated hole is inclined downward from the auxiliary wheel side to the main wheel side. Therefore, the connection shaft member that has moved toward the auxiliary wheel receives a force in the direction of sliding down along the elongated hole due to the load that the frame receives from the vehicle body. Therefore, the driving force of the linear motion actuator can be reduced. Alternatively, for example, a mechanism capable of switching between a state in which driving force for assisting the sliding of the connecting shaft member is transmitted from the driving source of the linear actuator and a state in which it is not transmitted is further provided, and the connecting shaft is operated in the state in which the driving force is not transmitted. The member may be automatically returned to the main wheel side by the load received from the vehicle body.

A vehicle according to an aspect of the present invention includes the caster and the vehicle body to which the bracket is attached. The caster can be transformed between a state in which only the main wheels are in contact with the running surface and a state in which the main wheels and auxiliary wheels are in contact with the running surface by rotating the frame with respect to the brackets attached to the vehicle body. is. That is, the auxiliary wheels can be brought into contact with the upper running surface of the step while the main wheels are in contact with the lower running surface of the step. Further, in this state, by sliding the bracket attached to the vehicle body to the side where the auxiliary wheels are provided with respect to the frame, the shared load received from the vehicle body moves from the main wheel side to the auxiliary wheel side. As a result, it is possible to reduce the propulsive force required to walk over the step.

Advantageous Effects of Invention According to the present invention, it is possible to provide a caster and a vehicle that have a simple structure and are capable of reducing the force required to climb over a step.

1 is a schematic side view of a caster according to a first embodiment; FIG. 2 is a schematic side view showing a deformed state of the caster shown in FIG. 1. FIG. 3 is a schematic side view showing a state in which the caster shown in FIG. 1 is further deformed from the state shown in FIG. 2. FIG. 4 is an explanatory diagram for explaining the thrust reduction effect in the state shown in FIG. 3 of the caster shown in FIG. 1. FIG. 5 is a schematic side view showing a state in which the caster shown in FIG. 1 is further deformed from the state shown in FIG. 3. FIG. FIG. 6 is a schematic side view of a caster according to the second embodiment. 7 is a schematic side view showing a state in which the caster shown in FIG. 6 is deformed; FIG. 8 is a schematic side view showing a state in which the caster shown in FIG. 6 is further deformed from the state shown in FIG. 7. FIG. 9 is an explanatory diagram for explaining the thrust reduction effect in the state shown in FIG. 8 of the caster shown in FIG. 6. FIG. 10 is a schematic side view showing a state in which the caster shown in FIG. 6 is further deformed from the state shown in FIG. 8. FIG.

A form (embodiment) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the contents described in the following embodiments. In addition, the components described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the components described below can be combined as appropriate.

[First Embodiment]
First, the configuration of the caster 10 according to the first embodiment will be described with reference to FIGS. 1 to 5. FIG. FIG. 1 is a schematic side view of a caster 10 according to the first embodiment. FIG. 2 is a schematic side view showing a state in which the caster 10 shown in FIG. 1 is deformed. FIG. 3 is a schematic side view showing a state in which the caster 10 shown in FIG. 1 is further deformed from the state shown in FIG. FIG. 4 is an explanatory diagram for explaining the thrust reduction effect in the state shown in FIG. 3 of the caster 10 shown in FIG. FIG. 5 is a schematic side view showing a state in which the caster 10 shown in FIG. 1 is further deformed from the state shown in FIG.

1 to 5 show various different attitude states of the caster 10 according to the first embodiment. FIG. 1 shows a state in which the caster 10 is in contact with a step St located forward in the running direction on a running surface Gs on which the caster 10 runs. 2, 3 and 4 show a state in which the caster 10 is deformed to climb over the step St. FIG. FIG. 5 shows the state immediately after the caster 10 gets over the step St.

Further, in the following description, the rotation direction in which the caster 10 can walk over a step is referred to as forward rotation direction Rf, and the rotation direction opposite to forward rotation direction Rf is referred to as reverse rotation direction Rr. The traveling direction when the caster 10 rotates in a step-walkable direction is leftward in FIGS. 1 to 5 . The forward rotation direction Rf is the counterclockwise direction in FIGS. 1 to 5 . The reverse rotation direction Rr is clockwise in FIGS. Among the running surfaces Gs, the lower running surface Gs in front of the step St is called a first running surface Gs1, and the upper running surface Gs beyond the step St is called a second running surface Gs2.

The caster 10 of the first embodiment is attached to a predetermined portion of the vehicle body 102 for traveling of the vehicle body 100 such as a walking aid, an autonomous mobile robot, an electric wheelchair, a self-propelled wheelchair, a silver car, a stroller, and a trolley. It is a member for running that is attached. The casters 10 are, for example, rotatably attached to the lower portion of the vehicle body 102 . The casters 10 are arranged, for example, at least two locations in front of the vehicle body 102 symmetrically with respect to the vehicle 100 . The caster 10 includes a frame 20 , main wheels 30 , auxiliary wheels 40 , brackets 50 , connection mechanisms 70 and direct acting actuators 80 .

The frame 20 is a structure that supports a large-diameter main wheel 30 and a small-diameter auxiliary wheel 40 and is supported by a bracket 50 attached to the vehicle body 102 . The frame 20 rotatably supports the main wheel 30 around a horizontal axis (main wheel axle Am) in the vicinity of the rear end portion in the running direction. The frame 20 supports the auxiliary wheel 40 so as to be rotatable about a horizontal axis (an auxiliary wheel axle Aa) in the vicinity of the front end in the running direction. The frame 20 is supported by the bracket 50 so as to be rotatable about a horizontal axis (connection axis Ac) and slidable within a predetermined range of movement in the sliding direction Ls. The sliding direction Ls is one direction perpendicular to the connection axis Ac. The sliding direction Ls extends from the front of the frame 20 (the side of the auxiliary wheels 40) to the rear (the side of the main wheels) when both the main wheels 30 and the auxiliary wheels 40 are in contact with the ground on the same plane (for example, the state shown in FIG. 5). 30 side).

The frame 20 is formed with an elongated hole 24 having a longitudinal direction in the sliding direction Ls. The elongated hole 24 is formed in the vicinity of the upper end of the frame 20 and extends from the vicinity of the front end of the frame 20 toward the vicinity of the rear end thereof. A front end portion of the elongated hole 24 is positioned forward of at least the main wheel axle Am. A rear end portion of the elongated hole 24 is positioned at least rearward of the main wheel axle Am. Since the elongated hole 24 is provided along the sliding direction Ls, when both the main wheel 30 and the auxiliary wheel 40 are in contact with the ground on the same plane (for example, the state shown in FIG. 5), the front of the frame 20 ( It is provided so as to incline downward from the auxiliary wheel 40 side) toward the rear (main wheel 30 side). The long hole 24 penetrates in a direction parallel to the main wheel axle Am in the first embodiment. The long hole 24 constitutes a connection mechanism 70 that connects the frame 20 and the bracket 50 together with a connection shaft member 72 to be described later. A connection shaft member 72 is inserted through the elongated hole 24 .

The main wheels 30 have a larger diameter than the auxiliary wheels 40 . The main wheel 30 having a larger diameter is advantageous for step climbing. The main wheel 30 is arranged in the vicinity of the rear end portion of the frame 20 and is provided rotatably around the main wheel axle Am with respect to the frame 20 . In the first embodiment, the main wheel 30 is supported by the frame 20 via a main wheel axle member 32 centered on the main wheel axle Am. The main wheel axle member 32 is a cylindrical shaft member in the first embodiment. The main wheel axle member 32 may be fixed to the frame 20 to rotatably support the main wheel 30 around the main wheel axle Am, or may be fixed to the main wheel 30 to support the main wheel axle Am relative to the frame 20 . It may be supported so as to be rotatable around.

The auxiliary wheels 40 have a smaller diameter than the main wheels 30 . Even if the auxiliary wheel 40 has a small diameter, it does not affect step climbing. The auxiliary wheel 40 is arranged near the front end of the frame 20 and is rotatable with respect to the frame 20 around the auxiliary wheel axle Aa. In the first embodiment, the safety wheel 40 is supported by the frame 20 via a safety wheel axle member 42 centered on the safety wheel axle Aa. The auxiliary wheel axle member 42 is a cylindrical shaft member in the first embodiment. The auxiliary wheel axle member 42 may be fixed to the frame 20 to support the auxiliary wheel 40 rotatably about the auxiliary wheel axle Aa, or fixed to the auxiliary wheel 40 to support the auxiliary wheel axle Aa relative to the frame 20 . It may be supported so as to be rotatable around.

The bracket 50 is attached to a predetermined fixed portion of the vehicle body 102 and connects the frame 20 to the vehicle body 102 . Bracket 50 includes a connection portion 52 , a fixed portion 54 and an extension portion 56 .

The connection portion 52 is configured near the lower end portion of the bracket 50 . The connection portion 52 is connected to the frame 20 via the connection mechanism 70 so as to be rotatable about the connection axis Ac with respect to the frame 20 and slidable within a predetermined range of movement in the sliding direction Ls. be. In the first embodiment, a connection shaft member 72 having a connection shaft Ac of a connection mechanism 70 (to be described later) as an axis is fixed to the connection portion 52 .

The fixing portion 54 is configured near the upper end portion of the bracket 50 . The fixed portion 54 is attached to a predetermined fixed portion of the vehicle body 102 . The fixing portion 54 , for example, pivotally connects the bracket 50 to the vehicle body 102 . The fixing portion 54 is positioned forward of the connecting portion 52 in the traveling direction of the caster 10 .

An extension 56 indicates a central portion of the bracket 50 that extends between the connecting portion 52 and the fixed portion 54 . In the first embodiment, the extending portion 56 is provided so as to extend downward from the fixing portion 54 toward the connecting portion 52 located on the rear side. As shown in FIGS. 1 and 2, when the frame 20 is rotated in the reverse rotation direction Rr about the main wheel axle Am, the lower surface 58 of the extension portion 56 has an inclination angle equal to that of the upper end surface 22 of the frame 20. with respect to the horizontal plane. The extending portion 56 abuts against the frame 20 rotating in the reverse rotation direction Rr about the main wheel axle Am with respect to the bracket 50, and serves as a stopper that restricts further rotation of the frame 20 in the reverse rotation direction Rr. have a function. In the first embodiment, the lower surface 58 as a stopper is provided with a cushioning material 60 that reduces the impact when the frame 20 collides with it.

The connection mechanism 70 connects the frame 20 and the bracket 50 rotatably about a horizontal axis (connection axis Ac) and slidably in a sliding direction Ls perpendicular to the connection axis Ac within a predetermined movement range. The connection mechanism 70 includes the elongated hole 24 formed in the frame 20 and the connection shaft member 72 fixed to the connection portion 52 of the bracket 50 in the first embodiment.

The connection shaft member 72 is a cylindrical shaft member having the connection shaft Ac as its axis. The connection shaft member 72 is rotatable in the long hole 24 around the connection shaft Ac, which is the axis. Further, the connection shaft member 72 is slidable in the long hole 24 in the sliding direction Ls. The connecting shaft member 72 slides in the elongated hole 24 between at least a first position P1 shown in FIGS. 2, 3, 4 and 5 and a second position P2 shown in FIG. It is possible.

The second position P2 is on the rear side of the frame 20 where the main wheel 30 is provided, and is positioned at least rearward of the main wheel axle Am. When the connection shaft member 72 is in the second position P2 shown in FIG. receive. Therefore, in the caster 10, the main wheels 30 contact the running surface Gs and the auxiliary wheels 40 rise from the running surface Gs.

When the connection shaft member 72 is in the second position P2 shown in FIG. are in contact with each other, the frame 20 is restricted from rotating in the reverse rotation direction Rr about the main wheel axle Am. That is, the caster 10 maintains a state in which the auxiliary wheels 40 are lifted from the running surface Gs. In such a state, the caster 10 can run only on the main wheels 30 during normal running on the running surface Gs without the step St.

In addition, the second position P2 includes the end portion on the side where the main wheel 30 is provided in the range in which the connection shaft Ac of the connection shaft member 72 can move. contains the position where is subjected to a force in the opposite direction of rotation Rr about the main wheel axle Am. The second position P2 can vary within a predetermined range depending on the height of the step St, the shape of the frame 20, and the like.

The first position P1 is nearer to the front of the frame 20 where the auxiliary wheels 40 are provided, and is located at least forward of the main wheel axle Am. When the connection shaft member 72 is in the first position P1 shown in FIGS. It receives a force in the forward rotation direction Rf. Therefore, in the caster 10, the main wheels 30 are in contact with the running surface Gs and the auxiliary wheels 40 are in contact with the running surface Gs.

That is, by moving the connection shaft member 72 from the second position P2 to the first position P1, not only the main wheels 30 but also the auxiliary wheels 40 share the load that the caster 10 receives from the vehicle body 102. As the connecting shaft Ac is separated from the main wheel axle Am toward the side on which the auxiliary wheels 40 are provided, the torque applied to the frame 20 in the positive rotation direction Rf increases. The shared load acting on the wheel 30 is reduced.

Note that the first position P1 includes the end portion of the range in which the connection shaft Ac of the connection shaft member 72 is movable, on the side where the auxiliary wheels 40 are provided. contains the position where receives force in the forward rotation direction Rf about the main wheel axle Am. The first position P1 can vary within a predetermined range depending on the height of the step St, the shape of the frame 20, and the like.

The linear motion actuator 80 is provided so as to be able to drive the connection shaft Ac in the sliding direction Ls with respect to the frame 20 . The linear motion actuator 80 includes a pair of fixed bases 82, a guide member 84, a ball screw 86, a motor 88, and a movable portion 90 in the first embodiment.

The pair of fixing bases 82 are provided on the front end side and the rear end side of the long hole 24 formed in the frame 20 at positions sandwiching the long hole 24 in the longitudinal direction when viewed in the direction of the connection axis Ac. The fixed base 82 is fixed to the frame 20 or provided integrally with the frame 20 .

The guide member 84 guides the sliding movement of the movable portion 90 in the sliding direction Ls and restricts the rotation of the movable portion 90 about an axis parallel to the sliding direction Ls. The guide members 84 are a pair of shafts in the first embodiment, but may be, for example, a pair of rails in the present embodiment. The pair of guide members 84 are provided between the pair of fixed bases 82 along the sliding direction Ls at positions sandwiching the elongated hole 24 in the lateral direction when viewed in the direction of the connection axis Ac.

A ball screw 86 is provided between the pair of fixed bases 82 along the sliding direction Ls. The ball screw 86 is supported by the pair of fixed bases 82 so as to be rotatable about the axis. The ball screw 86 moves the movable portion 90 in the sliding direction Ls by rotating about its axis.

A motor 88 outputs a rotational drive force for rotating the ball screw 86 about its axis. The motor 88 is rotationally driven, for example, by electric power supplied from a power source provided in the vehicle body 102 to which the casters 10 are attached.

The movable portion 90 is supported by the guide member 84 so as to be slidable in the sliding direction Ls. As the ball screw 86 rotates, the movable portion 90 slides in the sliding direction Ls depending on the direction and amount of rotation of the ball screw 86 . The movable portion 90 is connected to the connection shaft member 72 of the connection mechanism 70 so as to be relatively rotatable around the connection shaft Ac. As the movable portion 90 slides in the sliding direction Ls, the connecting shaft Ac of the connecting shaft member 72 moves along the elongated hole 24 in the sliding direction Ls.

A step-over operation of the caster 10 according to the first embodiment will be described with reference to FIGS. 1 to 5. FIG. 1 to 5 show various different posture states when the caster 10 according to the first embodiment climbs over the step St. As shown in FIG. In the following description, it is assumed that the user pushes forward the vehicle body 102 of the vehicle 100 to which the casters 10 are attached to move the vehicle.

As shown in FIG. 1, when the connection shaft member 72 is at the second position P2 in the elongated hole 24, the frame 20 rotates in the reverse rotation direction Rr around the main wheel axle Am due to the load that the caster 10 receives from the vehicle body 102. While receiving the force, the upper end surface 22 comes into contact with the cushioning material 60 provided on the lower surface 58 of the extension portion 56 of the bracket 50 . As a result, the caster 10 maintains a state in which the auxiliary wheels 40 are lifted from the running surface Gs, so that the caster 10 can run only with the main wheels 30 during normal running on the running surface Gs without a step St.

As shown in FIG. 1, when the caster 10 reaches the step St while the auxiliary wheels 40 are lifted from the running surface Gs (first running surface Gs1), the main wheels 30 first come into contact with the step St. At this time, the auxiliary wheels 40 pass over the step St while being lifted from the running surface Gs, and are positioned above the second running surface Gs2 above the step St.

Next, as shown in FIG. 2 , when the vehicle body 102 is pushed forward with the main wheels 30 in contact with the step St, the connection shaft member 72 fixed to the bracket 50 connected to the vehicle body 102 is pulled into the long hole 24 . At the same time, the direct acting actuator 80 is driven to move the connecting shaft member 72 forward along the long hole 24 via the movable portion 90. 1 to the position P1. As a result, the direction of the force of the load that the caster 10 receives from the vehicle body 102 gradually moves from the rear to the front of the main wheel axle Am with respect to the connection axis Ac.

Next, as shown in FIG. 3 , when the vehicle body 102 is further pushed forward, the connection shaft member 72 slides forward along the long hole 24 . At this time, at the same time, the direct acting actuator 80 is driven to assist the forward movement of the connection shaft member 72 along the elongated hole 24 via the movable portion 90 . As a result, the frame 20 receives a force in the forward rotation direction Rf around the main wheel axle Am due to the load that the caster 10 receives from the vehicle body 102 . As a result, the frame 20 rotates about the main wheel axle Am in the forward rotation direction Rf, and the floating auxiliary wheels 40 descend and touch the second running surface Gs2.

When the vehicle body 102 is further pushed forward from the state shown in FIG. 3 , the connection shaft member 72 slides forward along the long hole 24 . At this time, at the same time, the direct acting actuator 80 is driven to assist the forward movement of the connection shaft member 72 along the elongated hole 24 via the movable portion 90 . As a result, the connecting shaft Ac is separated from the main wheel axle Am to the side where the auxiliary wheels 40 are provided, so that the torque applied to the frame 20 in the forward rotation direction Rf increases, and the shared load acting on the auxiliary wheels 40 increases. Along with this, the shared load acting on the main wheel 30 decreases. Here, as shown in Equation 4 below, the thrust required to walk over a step (the user's force pushing forward the vehicle body 102 of the vehicle 100 to which the casters 10 are attached) is proportional to the applied load. Therefore, the shared load acting on the auxiliary wheels 40 increases and the shared load acting on the main wheels 30 decreases. At the timing when the threshold of the required thrust falls below the force with which the vehicle body 102 is pushed by the user, the vehicle body 102 moves over the step St while leaving the first running surface Gs1 while using the corner of the step St as a fulcrum.

As shown in FIG. 5, the main wheel 30 completely overcomes the step St and both the main wheel 30 and the auxiliary wheel 40 are in contact with the second running surface Gs2 above the step St. From this state, the direct acting actuator 80 is driven to assist the movement of the connecting shaft member 72 along the long hole 24 to the rear second position P2 via the movable portion 90 . As a result, the frame 20 receives a force in the forward rotation direction Rf around the main wheel axle Am due to the load applied to the caster 10 from the vehicle body 102, so that the caster 10 lifts the auxiliary wheel 40 from the running surface Gs again, and the main wheel 30 run only.

Here, in the state shown in FIG. 5, that is, in a state in which both the main wheels 30 and the auxiliary wheels 40 are in contact with the ground on the same plane (second running surface Gs2), the elongated holes 24 are opened from the auxiliary wheels 40 side. It is in a posture inclined downward toward the wheel 30 side. Therefore, the connection shaft member 72 that has moved forward (the auxiliary wheels 40 ) of the frame 20 receives a force in the direction of sliding down along the long hole 24 due to the load that the frame 20 receives from the vehicle body 102 . Therefore, the rotational torque of the motor 88 of the linear motion actuator 80 can be reduced. Alternatively, for example, between the output shaft of the motor 88 and the ball screw 86, a clutch mechanism capable of switching between a state in which the rotational driving force is transmitted and a state in which it is not transmitted is provided, and the connecting shaft member is engaged in the state in which the rotational driving force is not transmitted. 72 may be automatically returned to the second position P2 by the load received from the vehicle body 102 .

In order to obtain the thrust reduction effect in the caster 10 of the first embodiment, for example, design parameters may be set as follows. That is, as shown in FIG. 4, F is the thrust force for pushing the vehicle body 102 forward with the main wheels 30 in contact with the step St, Wb is the load received from the vehicle body 102, N is the drag force from the casters 10, Assuming that the inclination angle of the long hole 24 with respect to the horizontal is θ, and the contact angle of the main wheel 30 with respect to the step St is φ, the following equations 1 to 4 are obtained.

が段差踏破に必要な推力であることが知られており、また、tanが単調増加な関数であることから、（π／２）－θ＞φを満たすように設計すれば、推力低減効果を見込める。一例として、主輪３０の直径を２００ｍｍ、段差Ｓｔの高さを５０ｍｍとすると、接触角φは約３０°となる。長穴２４の傾斜角度θを６０°より小さくなるよう設計すれば、推力低減効果が見込める。定性的には、「車輪で段差を越える」のではなく、「長穴をスロープのように利用して段差の上に登る」ため、この低減効果が得られる。 where, for a normal wheel,

is known to be the thrust required to climb over a step, and tan is a monotonically increasing function. Expected. As an example, if the diameter of the main wheel 30 is 200 mm and the height of the step St is 50 mm, the contact angle φ is about 30°. If the oblong hole 24 is designed so that the inclination angle θ is smaller than 60°, a thrust reduction effect can be expected. Qualitatively, this reduction effect can be obtained because "climbing the step by using the long hole like a slope" instead of "crossing the step with wheels".

Furthermore, by assisting the movement of the connecting shaft member 72 to the rearward second position P2 along the elongated hole 24 via the movable portion 90 by the linear motion actuator 80, the user can apply a very small thrust force. Only by giving it, the caster 10 can be made to walk over a step.

As described above, the caster 10 of the first embodiment includes the frame 20 , the main wheels 30 rotatably supported around the main wheel axle Am horizontal to the frame 20 , and the main wheels 30 with respect to the frame 20 . An auxiliary wheel 40 rotatably supported around an auxiliary wheel axle Aa parallel to a wheel axle Am, a bracket 50 attached to a vehicle body 102, and a frame 20 and bracket 50 rotatable around a horizontal connection axis Ac. and a connection mechanism 70 that is slidably connected within a predetermined movement range in a sliding direction Ls perpendicular to the connection axis Ac. Further, the vehicle 100 of the first embodiment includes casters 10 and the vehicle body 102 to which the brackets 50 are attached.

In the caster 10 of the first embodiment, the frame 20 rotates with respect to the bracket 50 attached to the vehicle body 102, so that only the main wheels 30 are brought into contact with the running surface Gs, and the main wheels 30 and the auxiliary wheels 40 are brought into contact with each other. It can be deformed between a state in which it is grounded on the running surface Gs and a state in which it is grounded. That is, while the main wheels 30 are in contact with the first running surface Gs1 below the step St, the auxiliary wheels 40 can be placed in contact with the second running surface Gs2 above the step St. Further, in this state, by sliding the bracket 50 attached to the vehicle body 102 to the side where the auxiliary wheels 40 are provided with respect to the frame 20, the shared load received from the vehicle body 102 is shifted from the main wheels 30 side to the auxiliary wheels 40 side. move to the side. As a result, it is possible to reduce the propulsive force required to walk over the step.

Further, the caster 10 of the first embodiment includes a direct acting actuator 80 capable of driving the connecting shaft Ac with respect to the frame 20 in the sliding direction Ls. As a result, it is possible to assist the movement of the bracket 50 toward the auxiliary wheel 40 with respect to the frame 20, thereby further reducing the propulsive force required for step climbing.

In addition, in the caster 10 of the first embodiment, when the connection shaft Ac moves to the side where the auxiliary wheels 40 are provided within the movement range, the auxiliary wheels 40 come into contact with the running surface Gs, and the weight of the vehicle body 102 applied to the main wheels 30 is shared. As the load decreases, the shared load of the vehicle body 102 applied to the auxiliary wheels 40 increases. As a result, it is possible to efficiently and effectively move the load necessary for stepping over the step, so that the main wheels 30 can more easily climb over the step.

Further, in the caster 10 of the first embodiment, when the connecting shaft Ac is at the end of the movement range on the side where the main wheels 30 are provided with respect to the auxiliary wheels 40, the auxiliary wheels 40 are lifted from the running surface Gs. maintain. As a result, it is possible to run only with the main wheels 30 during normal running on the running surface Gs without the step St.

In addition, in the caster 10 of the first embodiment, the bracket 50 is a stopper (in the first embodiment, an extended It has a cushioning material 60 provided on the lower surface 58 of the portion 56 . As a result, the frame 20 does not rotate in the reverse rotation direction Rr more than necessary, and unstable running due to excessive lifting of the frame 20 can be avoided.

In addition, in the caster 10 of the first embodiment, the connection mechanism 70 is provided on the bracket 50 and formed on the frame 20, and the connection shaft member 72 having the connection axis Ac as the connection axis Ac. a long hole 24 connected rotatably about and slidably in the sliding direction Ls. As a result, the connection mechanism 70 can be realized in a simple form, and the connection mechanism 70 can perform both the sliding function and the rotating function of the frame 20 and the bracket 50 at the same time. In addition, the connection shaft member 72 and the elongated hole 24 allow the bracket 50 to slide smoothly with respect to the frame 20, enabling smooth load transfer as if sliding up a slope. Therefore, the thrust reduction effect can be obtained effectively and efficiently.

In addition, in the caster 10 of the first embodiment, the long hole 24 extends downward from the side of the auxiliary wheel 40 toward the side of the main wheel 30 when both the main wheel 30 and the auxiliary wheel 40 are in contact with the ground on the same plane. It is provided so as to incline. As a result, when both the main wheels 30 and the auxiliary wheels 40 are in contact with the ground on the same plane (the second running surface Gs2), the elongated holes 24 extend downward from the auxiliary wheels 40 side toward the main wheels 30 side. It is a tilted posture. Therefore, the connecting shaft member 72 that has moved toward the auxiliary wheel 40 receives a force in the direction of sliding down along the long hole 24 due to the load that the frame 20 receives from the vehicle body 102 . Therefore, the rotational driving force of the linear motion actuator 80 can be reduced. Alternatively, for example, a mechanism capable of switching between a state in which the driving force that assists the sliding of the connection shaft member 72 is transmitted from the driving source of the linear actuator 80 and a state in which it is not transmitted is provided, and the connection is performed in the state in which the driving force is not transmitted. The shaft member 72 may be automatically returned to the second position P2 by the load received from the vehicle body 102 .

[Second embodiment]
Next, the configuration and operation of the caster 110 according to the second embodiment will be described with reference to FIGS. 6 to 10. FIG. FIG. 6 is a schematic side view of caster 110 according to the second embodiment. FIG. 7 is a schematic side view showing a state in which caster 110 shown in FIG. 6 is deformed. FIG. 8 is a schematic side view showing a state in which the caster 110 shown in FIG. 6 is further deformed from the state shown in FIG. FIG. 9 is an explanatory diagram for explaining the thrust reduction effect in the state shown in FIG. 8 of the caster 110 shown in FIG. 10 is a schematic side view showing a state in which caster 110 shown in FIG. 6 is further deformed from the state shown in FIG.

6-10 show the caster 110 according to the second embodiment in various different positions. Specifically, FIG. 6 shows a state in which the main wheels 130 of the casters 110 are in contact with the step St of the running surface Gs, that is, the main wheels 130 running on the first running surface Gs1 below the step St are in contact with the step. In FIG. 7, the bracket 150 of the caster 110 along with the vehicle body 202 is pushed forward by the thrust (the user's force pushing the vehicle body 202 of the vehicle 200 to which the caster 110 is attached) to overcome the step St. FIGS. 8 and 9 show a state in which the auxiliary wheels 140 of the caster 110 are in contact with the second running surface Gs2 on the upper side of the step St as a result of sliding in FIG. 7, and FIGS. 9 shows a state in which the main wheels 130 completely ride over the step St from the state of FIGS. 8 and 9 and both the main wheels 130 and the auxiliary wheels 140 are in contact with the second running surface Gs2 above the step St. there is

As shown in these figures, the caster 110 according to the second embodiment is attached (for example, turnable) to a predetermined portion of the vehicle body 202 so that the vehicle body 202 can travel. A frame 120 having a wheel 130 and a small-diameter auxiliary wheel 140, a bracket 150 for connecting the frame 120 to a vehicle body 202, and a connection mechanism for slidably and rotatably connecting the frame 120 and the bracket 150 to each other. 170.

The main wheels 130 are attached near the rear end of the frame 120 so as to be rotatable around a rotation axis (axle) 132 , and the auxiliary wheels 140 are mounted near the front end of the frame 120 on a rotation axis (axle) 142 . is mounted rotatably around the

Also, in this embodiment, the connection mechanism 170 has an elongated hole 124 formed in the frame 120 and a connecting portion 152 of the bracket 150 connected to the elongated hole 124 . In this case, the elongated hole 124 extends from the front end of the frame 120 where the auxiliary wheel 140 is positioned to the rear end of the frame 120 where the main wheel 130 is positioned (more than the rotation shaft 132) on the upper end side of the frame 120. extending to the rear) along the longitudinal direction (front-rear direction) of the frame 120 . 10 in which the main wheels 130 and the auxiliary wheels 140 are in contact with each other on the same plane in contact with the second running surface Gs2 on the upper side of the )), extending from the auxiliary wheel 140 side toward the main wheel 130 side so as to incline downward.

A bracket 150 for connecting the frame 120 to the vehicle body 202 includes an upper fixing portion 154 fixed (for example, pivotally attached) to a predetermined fixed portion of the vehicle body 202 and a frame 120 via a pivot 172, for example. It has a connecting portion 152 on the lower end side that is slidably and rotatably connected in the elongated hole 124 of the connecting portion 124 and an extending portion 156 that extends between the fixed portion 154 and the connecting portion 152 . become. In this case, the extension portion 156 extends from the fixed portion 154 so as to incline downward toward the rear connection portion 152, and the lower surface 158 thereof is in a normal running state (the connection portion 152 will be described later). In the second position P2), the auxiliary wheel 140 forms an inclination angle with respect to the horizontal plane that substantially corresponds to the inclination angle of the upper end surface 122 of the frame 120 that inclines (rotates around the pivot 172) so as to float up. It abuts against the frame 120 that rotates with respect to the bracket 150 and functions as a stopper that restricts further rotation of the frame 120 . A cushioning material 160 is provided on the lower surface 158 as a stopper to reduce the impact when the frame 120 collides.

Also, the connecting portion 152 of the bracket 150 slidably and rotatably connected to the elongated hole 124 is positioned at least at a first position on the auxiliary wheel 140 side with respect to the rotating shaft 132 of the main wheel 130 . P1 (FIGS. 7, 8, 9 and 10 show an example of the first position P1; this first position P1 is determined by the height of the step St, the length of the frame 120, etc.). range) and a second position P2 (see FIG. 6) located opposite the first position P1 with respect to the axis of rotation 132. It's like Therefore, when the bracket 150 is connected to the vehicle body 202 and the connection portion 152 of the bracket 150 is at the second position P2 (state shown in FIG. 6), the load received from the vehicle body 202 causes the main wheels 130 to come into contact with the running surface Gs. As a result, the auxiliary wheels 140 come to float above the running surface Gs, so that the main wheels 130 alone can be used during normal running on a running surface without steps St. On the other hand, when the main wheels 130 run over a step (see FIGS. 7 and 8), the connecting portion 152 of the bracket 150 moves from the second position P2 to the first position P1, and the load shared by the vehicle body 202 is transferred to the auxiliary wheels. 140 side, so that the main wheels 130 are lifted from the first running surface Gs1 positioned below the step St, and the auxiliary wheels 140 are positioned above the step St in the second traveling mode. Contact can be made on the surface Gs2. That is, an effective amount of positional variation of the bracket 150 is ensured, and the load necessary for stepping over the step can be efficiently and effectively transferred.

The connection mechanism 170 that accompanies the movement of the connection portion 152 between the positions P1 and P2 along the elongated hole 124 is designed to prevent the frame 120 from moving over a step with the bracket 150 connected to the vehicle body 202 and the main wheel 130 running over a step. By allowing the bracket 150 to slide relative to the bracket 150 and the frame 120 to rotate relative to the bracket 150, the load shared by the vehicle body 202 can be moved from the main wheel 130 side to the auxiliary wheel 140 side. can be reduced. This will be described below with reference to FIG. In the following description, it is assumed that the user pushes forward the vehicle body 202 to which the casters 110 are attached to move the vehicle.

During normal running on the running surface Gs without steps, the auxiliary wheels 140 are in a state of floating from the running surface Gs, as shown in FIG. This state is realized by positioning the connecting portion 152 of the bracket 150 at the second position P2 positioned opposite to the auxiliary wheel 140 with respect to the rotating shaft 132 of the main wheel 130, and the load received from the vehicle body 202. , the auxiliary wheel 140 is maintained in a state of being lifted in the air.

When the casters 110 approach the step St on the running surface Gs (first running surface Gs1), the main wheels 130 first come into contact with the step St because the auxiliary wheels 140 are floating in the air. That state is shown in FIG. After that, when the vehicle body 202 is pushed forward while the main wheels 130 are pressed against the step St in this state, the connecting portion 152 of the bracket 150 connected to the vehicle body 202 slides along the long hole 124 as if going up the slope. As it slides upward, the shared load of the vehicle body 202 moves from the main wheel 130 side to the auxiliary wheel 140 side. As a result, the shared load acting on the safety wheel 140 side increases, the frame 120 rotates downward about the pivot 172, and the safety wheel 140 moves toward the second running surface Gs2 positioned above the step St. Contact. That state is shown in FIG. When the vehicle body 202 is further pushed forward and the bracket 150 slides forward along the long hole 124, the shared load acting on the auxiliary wheels 140 further increases and the shared load acting on the main wheels 130 decreases. The main wheels 130 are gradually lifted off the first running surface Gs1, and finally the main wheels 130 climb over the step St while the thrust required to overcome the step is reduced.

FIG. 10 shows a state in which the main wheels 130 have run over the step St. In this state, that is, in a state in which both the main wheels 130 and the auxiliary wheels 140 are in contact with each other on the same plane (second running surface Gs2), the elongated holes 124 forming the connection mechanism 170 are opened from the auxiliary wheels 140 side. It extends so as to incline downward toward the wheel 130 side. Therefore, the bracket 150, which had moved to the front of the frame 120 (toward the auxiliary wheels 140), receives the gravity associated with the load of the vehicle body 202 and slides down along the long holes 124, returning to its initial position (secondary wheel 140 side) on the main wheel 130 side. It can automatically return to position P2). Therefore, it is not necessary to separately provide a mechanism such as a spring that generates a restoring force for returning the caster to its original state as in the above-mentioned Patent Document 1, and the accompanying increase in thrust and weight can be avoided.

In order to actually obtain the thrust reduction effect using such a connection mechanism 170, for example, the design parameters should be set as follows. That is, as shown in FIG. 9, F is the thrust force for pushing the vehicle body 202 forward with the main wheels 130 in contact with the step St, Wb is the load received from the vehicle body 202, N is the drag force from the casters 110, Assuming that the angle of inclination of the elongated hole 124 with respect to the horizontal is θ, and the contact angle of the main wheel 130 with respect to the step St is φ, mathematically, similarly to the caster 10 of the first embodiment described above, from Equation 1 to Equation 4, represented as shown.

Here, in a normal wheel, it is known that the thrust force F shown in the above-mentioned formula 5 is the thrust force necessary for stepping over a step, and since tan is a monotonically increasing function, (π/2) If the design satisfies -θ>φ, a thrust reduction effect can be expected. As an example, if the diameter of the main wheel 130 is 200 mm and the height of the step St is 50 mm, the contact angle φ is about 30°. If the oblong hole 124 is designed so that the inclination angle θ is smaller than 60°, a thrust reduction effect can be expected. Qualitatively, this reduction effect can be obtained because "climbing the step by using the long hole like a slope" instead of "crossing the step with wheels".

As described above, the caster 110 of the second embodiment is a caster 110 that is attached to the vehicle body 202 so that the vehicle body 202 can travel. 202, and a connection mechanism 170 that slidably and pivotally connects the frame 120 and the bracket 150 to each other. When the main wheels 130 walk over a step in the standing state, the sliding of the brackets 150 with respect to the frame 120 and the rotation of the frame 120 with respect to the brackets 150 are allowed, and the shared load of the vehicle body 202 is shifted from the side of the main wheels 130 to the side of the auxiliary wheels 140. to enable.

According to the caster 110 of the second embodiment, the frame 120 and the bracket 150 are slidably and rotatably connected to each other by the connecting mechanism 170 , and the bracket 150 is attached to the vehicle body 202 by the action of the connecting mechanism 170 . When the main wheels 130 in the connected state go over a step, the bracket 150 slides with respect to the frame 120 and the frame 120 rotates with respect to the bracket 150, thereby sharing the load of the vehicle body 202 connected with the bracket 150. can move from the main wheel 130 side to the auxiliary wheel 140 side. Therefore, the vehicle body share load acting on the auxiliary wheels 140 gradually increases and the vehicle body share load acting on the main wheels 130 decreases, so that the propulsive force required for step climbing can be reduced. That is, the user who pushes the vehicle body 202 does not need to lift the weight of the vehicle body 202 by his or her own power in order to walk over the step (in order for the main wheels 130 to climb over the step St). (as if sliding up a slope), the shared load of the vehicle body 202 is moved from the main wheel 130 side to the auxiliary wheel 140 side (in the direction in which the vehicle body 202 moves forward). exert a force (propulsive force) on the Further, according to the caster 110 of the second embodiment, the force when the main wheels 130 collide with the step St is released forward by the sliding of the bracket 150 with respect to the frame 120, so that the impact at the time of collision with the step is reduced. can also be alleviated. In other words, according to the caster 110 of the second embodiment, the step St can be easily overcome with less force and without impact.

Further, in the caster 110 of the second embodiment, the connection mechanism 170 is formed by the elongated hole 124 formed in the frame 120 and to which the connection portion 152 of the bracket 150 is slidably and rotatably connected. The connection mechanism 170 can be realized in a simple form, and the connection mechanism 170 can simultaneously perform the sliding function and the rotating function of the frame 120 and the bracket 150 . In addition, such elongated holes 124 allow the bracket 150 to slide smoothly with respect to the frame 120, enabling smooth load transfer as if sliding up a slope. Therefore, the thrust reduction effect can be obtained effectively and efficiently.

Further, in the caster 110 of the second embodiment, the elongated hole 124 constituting the connection mechanism 170 is moved from the side of the auxiliary wheel 140 to the side of the main wheel 130 while the main wheel 130 and the auxiliary wheel 140 are in contact with each other on the same plane. extending downwards toward the According to this, when the main wheels 130 have completed stepping over the step (the main wheels 130 have completely run over the step St), that is, when the main wheels 130 and the auxiliary wheels 140 are in contact with each other on the same plane, Since the elongated hole 124 is inclined downward from the side of the auxiliary wheel 140 toward the side of the main wheel 130, the bracket 150, which had moved to the front of the frame 120 (toward the side of the auxiliary wheel 140), is displaced by the vehicle body 202 load. It can slide down along the slot 124 under gravity and automatically return to the initial position on the main wheel 130 side. Therefore, it is not necessary to separately provide a mechanism such as a spring that generates a restoring force for returning the caster to its original state, as in the above-mentioned Patent Document 1, so that the accompanying increase in thrust and weight can be avoided. .

In addition, in the second embodiment, the connection portion 152 of the bracket 150 is positioned at the first position P1 positioned on the auxiliary wheel 140 side with respect to the rotation axis 132 of the main wheel 130 and at the first position P1 with respect to the rotation axis 132. Since it is possible to slide in the long hole 124 between the position P1 and the second position P2 located on the opposite side, only the main wheels 130 can be used during normal running on a running surface without a step St. In addition to making it possible to travel, it is possible to climb over a step with the assistance of the auxiliary wheels 140 when stepping over a step. be able to do it effectively.

Specifically, when the bracket 150 is connected to the vehicle body 202 and the connection portion 152 of the bracket 150 is at the second position P2, the load received from the vehicle body 202 causes the main wheels 130 to come into contact with the running surface Gs and assist. The wheel 140 can be lifted from the running surface Gs. As a result, it is possible to run only with the main wheels 130 during normal running on the running surface Gs without the step St.

On the other hand, when the main wheels 130 walk over a step, when the connecting portion 152 of the bracket 150 moves from the second position P2 to the first position P1 and the load shared by the vehicle body 202 moves toward the auxiliary wheels 140, the main wheels 130 moves away from the first running surface Gs1 located below the step St while using the corner of the step St as a fulcrum, and the auxiliary wheel 140 comes into contact with the second running surface Gs2 located above the step St. As a result, it is possible to efficiently and effectively transfer the load necessary for stepping over the step, so that the main wheels 130 can more easily step over the step.

Further, in the caster 110 of the second embodiment, the bracket 150 is provided with a stopper (in the second embodiment, a , a cushioning material 160 provided on the lower surface 158 of the extension 156 is preferably provided. According to this, the frame 120 is prevented from rotating more than necessary by the stopper, and unstable running due to excessive lifting of the frame 120 can be avoided.

Note that the casters 10 and 110 and the vehicles 100 and 200 of the embodiments may have their configurations partially changed as appropriate.

For example, the main wheels 30 and 130 having a larger diameter are more advantageous for step climbing, and even if the auxiliary wheels 40 and 140 have a small diameter, they do not affect step step climbing. , is provided with a diameter larger than that of the auxiliary wheels 40 and 140 as a preferred example. However, the main wheels 30 , 130 are not limited to having a diameter larger than that of the auxiliary wheels 40 , 140 , and may have the same diameter as the auxiliary wheels 40 , 140 or a smaller diameter than the auxiliary wheels 40 , 140 .

Further, in each of the above-described embodiments, the connection mechanisms 70, 170 had the elongated holes 24, 124. Allowing the sliding of the brackets 50, 150 with respect to the frames 20, 120 and the rotation of the frames 20, 120 with respect to the brackets 50, 150 at the time of traversing, the shared load of the vehicle bodies 102, 202 is transferred from the side of the main wheels 30, 130 to the auxiliary wheels 40, The connection mechanisms 70 and 170 may have any form as long as the thrust force required for stepping over the step can be reduced by enabling the movement to the 140 side.

In addition, in the second embodiment described above, the connection portion 152 of the bracket 150 is returned to the second position P2 by gravity after the step is overcome by the oblique extending form of the long hole 124, but the connecting portion 152 is connected after the step is overcome. A separate return mechanism (such as a spring) may be provided to return the portion 152 to the second position P2. Further, part or all of the above-described embodiments may be combined without departing from the gist of the present invention, or part of the configuration may be omitted from one of the above-described embodiments. good too.

10, 110 caster 20, 120 frame 22, 122 upper end surface 24, 124 slotted hole 30, 130 main wheel 32 main wheel axle member 132 rotating shaft (axle)
40, 140 auxiliary wheel 42 auxiliary wheel axle member 142 rotating shaft (axle)
50, 150 Brackets 52, 152 Connecting Portions 54, 154 Fixing Portions 56, 156 Extension Portions 58, 158 Lower Surfaces 60, 160 Cushioning Materials 70, 170 Connecting Mechanism 72 Connecting Shaft Member 172 Pivot 80 Linear Motion Actuator 82 Fixed Base 84 Guide Member 86 ball screw 88 motor 90 movable part 100, 200 vehicle 102, 202 vehicle body Am main wheel axle Aa auxiliary wheel axle Ac connecting shaft Ls sliding direction Rf forward rotation direction Rr reverse rotation direction P1, P2 position Gs running surface Gs1 first Running surface Gs2 Second running surface St Step F Thrust Wb Load N Drag θ Tilt angle φ Contact angle

Claims (8)

a frame;
a main wheel rotatably supported around a main wheel axle horizontal with respect to the frame;
an auxiliary wheel rotatably supported by the frame about an auxiliary wheel axle parallel to the main wheel axle;
A bracket attached to the vehicle body,
a connection mechanism that connects the frame and the bracket rotatably about a horizontal connection shaft and slidably within a predetermined range of movement in a sliding direction perpendicular to the connection shaft;
Equipped with casters. a linear actuator capable of driving the connection shaft in the sliding direction with respect to the frame;
A caster according to claim 1. When the connecting shaft moves to the side of the movement range where the auxiliary wheels are provided, the auxiliary wheels come into contact with the running surface, and the shared load of the vehicle body applied to the main wheels decreases and the auxiliary wheels are applied to the auxiliary wheels. The shared load of the car body increases,
A caster according to claim 1 or 2. In a state in which the connecting shaft is at the end of the movement range on the side where the main wheels are provided with respect to the auxiliary wheels, the auxiliary wheels maintain a state in which they are lifted from the running surface.
Caster according to any one of claims 1 to 3. The bracket has a stopper that restricts a rotation range of the frame in a direction in which the auxiliary wheel is lifted from the running surface.
Caster according to any one of claims 1 to 4. The connection mechanism is
a connection shaft member provided in the bracket and having an axis center as the connection shaft;
an elongated hole formed in the frame and connected to the connection shaft member so as to be rotatable around the connection shaft and slidable in the sliding direction;
including,
Caster according to any one of claims 1 to 5. The elongated hole is provided so as to incline downward from the side of the auxiliary wheel toward the side of the main wheel when both the main wheel and the auxiliary wheel are in contact with the ground on the same plane.
7. Caster according to claim 6. A caster according to any one of claims 1 to 7;
the vehicle body to which the bracket is attached;
a vehicle.

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