JP7828638B2 - wheel structure - Google Patents

Description

This invention relates to a wheel structure, and more particularly, to a wheel structure that can easily overcome obstacles such as steps.

In transport devices that utilize human power as propulsion, such as carts for carrying luggage, strollers, and wheelchairs, small wheel structures are often used due to their size and weight. However, the environments in which these transport devices are used often contain numerous uneven surfaces and obstacles, making it difficult to smoothly move the wheels over these uneven surfaces with minimal force without damaging the transported goods.

Therefore, various techniques have been proposed to install a small-diameter auxiliary wheel in front of the main wheel, so that when encountering a step, the auxiliary wheel first makes contact with the top surface of the step, and then the main wheel rides up onto the top surface of the step (for example, Patent Document 1).

However, with conventional technology, the movement of the main wheel when returning to its initial state differed depending on the magnitude of the load on the main wheel, resulting in less-than-smooth movement before and after riding over obstacles. Therefore, further improvements are needed.

For example, in a spring-based technology like that described in Patent Document 1, if the load on the main wheel is greater than the spring's restoring force, the main wheel cannot be returned to its original position. Conversely, if the load on the main wheel is less than the spring's restoring force, the main wheel returns to its original position too quickly, potentially causing the transported goods to be subjected to shocks. Therefore, the movement before and after riding over obstacles was not smooth.

Japanese Patent Publication No. 2006-7855

In view of the problems of the prior art described above, the present invention aims to provide a wheel structure that can smoothly perform the act of riding over a step with minimal force, from the start to the completion of the ride.

The inventors of this invention conducted diligent research to solve the above problems and, as a result, discovered that the above problems can be solved by the invention described below, thus completing the present invention.

The invention described in claim 1 is,
A wheel structure having a large-diameter main wheel, a small-diameter auxiliary wheel, and a frame provided with a transport platform mounting section, wherein after the main wheel contacts a step, the auxiliary wheel contacts the upper surface of the step, and the main wheel rides up onto the upper surface of the step,
The frame supports the auxiliary wheel at its front lower end,
The frame has a hole formed in which a short hole extending downward and rearward and a long hole extending upward and rearward are connected by a curved hole, allowing the main wheel axle to be inserted.
A pinion gear is provided on the main wheel shaft via a switching mechanism that can switch between transmitting and not transmitting the rotation of the main wheel.
The frame is provided with a rack gear that can mesh with the pinion gear, extending from the curved portion of the hole to the elongated portion of the hole, along the rear side of the hole.
As the main wheel axle inserted through the hole moves through the hole, the main wheel rides up onto the step surface while forming a predetermined track.
The wheel structure is characterized in that the main wheel axle is configured to return to its state before contact with the step by moving the hole in the opposite direction to when it is driven over.

The invention described in claim 2 is,
As a means for transmitting the rotation of the main wheel, the main wheel and the pinion gear are each provided with interlocking protrusions and recesses.
The wheel structure according to claim 1 , characterized in that the switching means is composed of an engaging claw for engaging the uneven portion and an engagement disengaging claw for disengaging the uneven portion.

The invention described in claim 3 is,
The wheel structure according to claim 1 , characterized in that the switching means is a free-type bidirectional clutch provided between the main wheel axle and the pinion gear.

The invention described in claim 4 is,
The wheel structure according to claim 1 is characterized in that the switching means comprises an elastic body with one end fixed to the main wheel and the pinion gear, and a locking portion for rotation transmission provided on the main wheel and the pinion gear, respectively.

The invention described in claim 5 is,
The wheel structure according to claim 4 , characterized in that one or more intermediate rotating bodies, each having a locking portion for rotational transmission, are arranged between the main wheel and the pinion gear.

The invention described in claim 6 is,
The wheel structure according to any one of claims 1 to 5 , characterized in that the pinion gear and the rack gear are provided in pairs, symmetrically on both sides, so as to sandwich the main wheel and operate synchronously.

The invention described in claim 7 is,
A wheel structure having a large-diameter main wheel, a small-diameter auxiliary wheel, and a frame provided with a transport platform mounting section, wherein after the main wheel contacts a step, the auxiliary wheel contacts the upper surface of the step, and the main wheel rides up onto the upper surface of the step,
The frame supports the auxiliary wheel at its front lower end,
The frame has a hole formed in which a short hole extending downward and rearward and a long hole extending upward and rearward are connected by a curved hole, allowing the main wheel axle to be inserted.
The main wheel shaft is provided with a pinion gear that rotates together with the main wheel.
A rack gear is provided on the front side of the hole, along the hole,
A clutch gear is provided so as to mesh with the rack gear and move from the curved portion of the hole to the elongated portion of the hole.
An elastic body connected between the clutch gear and the pinion gear allows for switching between transmitting and not transmitting the rotation of the main wheel to the pinion gear .
As the main wheel axle inserted through the hole moves through the hole, the main wheel rides up onto the step surface while forming a predetermined track.
The wheel structure is characterized in that the main wheel axle is configured to return to its state before contact with the step by moving the hole in the opposite direction to when it is driven over .

The invention described in claim 8 is,
A wheel structure having a large-diameter main wheel, a small-diameter auxiliary wheel, and a frame provided with a transport platform mounting section, wherein after the main wheel contacts a step, the auxiliary wheel contacts the upper surface of the step, and the main wheel rides up onto the upper surface of the step,
The inner circumferential surface of the main wheel has a smooth surface area in which bearings, which are rotatably inserted through each of the three or more support columns provided on the main wheel, make contact, and a region where an internal gear is provided that meshes with a gear attached to the end of one of the bearings on the support column. The main wheel is supported by the rotation of each of the bearings on the support column.
The frame supports the auxiliary wheel at its front lower end,
The frame has two or more parallel rows of holes, each having a shape in which a short hole extending downward and a long hole extending upward and rear are connected by a curved hole.
As the support columns inserted through each of the holes move through the holes, the main wheel rides up onto the step surface while forming a predetermined track.
The wheel structure is characterized in that the main wheel axle is configured to return to its state before contact with the step by moving the hole in the opposite direction to when it is driven over.

According to the present invention, it is possible to provide a wheel structure that can perform a smooth step-climbing operation with minimal force, from the start to the completion of the step-climbing motion.

This is a schematic side view of a wheel structure according to the first embodiment of the present invention. This is a schematic front view of a wheel structure according to the first embodiment of the present invention. This is a schematic perspective view illustrating a transmission means for transmitting the rotation of the main wheel to the pinion gear in a first embodiment of the present invention. This is a schematic side view showing the state when the main wheel is in contact with the stepped end face in the first embodiment of the present invention. This is a schematic side view illustrating the state in which the pinion gear is moving along the elongated hole in the first embodiment of the present invention. This is a schematic side view illustrating the state in which the main wheel is mounted on the upper surface of a step in the first embodiment of the present invention. This is a schematic perspective view illustrating the engagement between a recess and a protrusion in the first embodiment of the present invention. This is a schematic side view illustrating the state of the pinion gear when it reaches the curved hole in the first embodiment of the present invention. This is a schematic perspective view illustrating the release of engagement between a recess and a protrusion by an engagement release claw in a first embodiment of the present invention. This is a schematic side view showing an example of a wheel structure in which a free-type bidirectional clutch is used as a switching means in a first modification of the first embodiment of the present invention. This is a schematic perspective view illustrating a second modified example of the first embodiment of the present invention, showing the combination of an elastic body and the locking portion of the main ring and the locking portion of the pinion gear. This is a schematic perspective view illustrating the state of the main wheel and pinion gear during normal operation in a second modified example of the first embodiment of the present invention. This is a schematic perspective view showing the state of the main wheel and pinion gear when the main wheel rides up on the upper surface of a step in a second modified example of the first embodiment of the present invention. This is a schematic perspective view showing a second modification of the first embodiment of the present invention, in which an intermediate rotating body is arranged between the main wheel and the pinion gear. This is a front view of the wheel structure in a third modification of the first embodiment of the present invention, specifically in modification 1 of Example 1. Figure 15 is a schematic perspective view illustrating the gear coupling section. This is a schematic side view of a wheel structure according to a second embodiment of the present invention. This is a schematic front view of a wheel structure according to a second embodiment of the present invention. This is a schematic side view illustrating a state in a second embodiment of the present invention in which the clutch gear is meshed with the rack gear and moving along the elongated hole. This is a schematic side view illustrating a state in which the main wheel is mounted on the upper surface of a step in a second embodiment of the present invention. This figure illustrates the state of the clutch gear when it reaches its initial position near the curved hole in a second embodiment of the present invention. This is a schematic side view of a wheel structure according to a third embodiment of the present invention. This is a schematic front view of a wheel structure according to a third embodiment of the present invention. This is a schematic side view showing the state when the main wheel is in contact with the stepped end face in a third embodiment of the present invention. This is a schematic side view showing the state when the auxiliary wheel is in contact with the upper surface of a step in a third embodiment of the present invention. This is a schematic side view showing the state when the main wheel has completely driven onto the upper surface of the step in a third embodiment of the present invention. This is a schematic side view illustrating the movement of the frame in a third embodiment of the present invention. This is a schematic side view illustrating the state immediately before the frame and auxiliary wheels return to their initial positions in a third embodiment of the present invention. This is a schematic side view of a wheel structure according to a fourth embodiment of the present invention. This is a schematic front view of a wheel structure according to a fourth embodiment of the present invention. This is a schematic perspective view illustrating the rotation of the main wheel in a fourth embodiment of the present invention. This is a schematic exploded perspective view illustrating the mounting of the main wheel in the fourth embodiment of the present invention. This is a schematic side view showing the state when the main wheel is in contact with the stepped end face in the fourth embodiment of the present invention. This is a schematic side view showing the state when the main wheel has completely driven onto the upper surface of the step in the fourth embodiment of the present invention. This is a schematic cross-sectional view showing the state when each of the two support columns reaches the upper end within each hole in the fourth embodiment of the present invention. This is a schematic side view illustrating the movement of the frame in a fourth embodiment of the present invention.

The present invention will be specifically described below, using four embodiments (the first to fourth embodiments) as examples.

1. First Embodiment (1) Wheel Structure Configuration Figure 1 is a schematic side view of the wheel structure according to this embodiment, and Figure 2 is a schematic front view of the same wheel structure. Figure 3 is a schematic perspective view illustrating the transmission means for transmitting the rotation of the main wheel 2 to the pinion gear 5 in this embodiment.

In Figures 1 to 3, 1 is the frame, 2 is the main wheel, 3 is the auxiliary wheel, and 4 is the mounting section for the transport platform.

As shown in Figures 1 and 2, the wheel structure according to this embodiment has a frame 1 equipped with a large-diameter main wheel 2, a small-diameter auxiliary wheel 3, and a transport platform mounting portion 4. The frame 1 supports the auxiliary wheel 3 at its front lower end, and the frame 1 has a hole 6 formed therein, which has a short hole 6a extending downward and rearward and a long hole 6b extending upward and rearward, connected by a curved hole 6c. The main wheel axle (main wheel axle) 2a is inserted through the hole 6.

A pinion gear 5 is provided on the main axle 2a, and a rack gear 9 is provided on the frame 1, extending from the curved hole 6c to the elongated hole 6b of the hole 6, so as to be able to mesh with the pinion gear 5. A taper 5a is formed on the side of the pinion gear 5 facing the frame 1. In the rack gear 9, 9a is the elongated portion along the elongated hole 6b of the hole 6, and 9b is the curved portion along the curved hole 6c of the hole 6.

Furthermore, 2b is a recess formed on the surface that protrudes outward from the main wheel 2. As shown in Figures 2 and 3, it engages with a protrusion 5b on the pinion gear 5, thereby transmitting the rotation of the main wheel 2, which rotates forward (counterclockwise on paper), to the pinion gear 5. On the other hand, by disengaging the recess 2b and the protrusion 5b, the rotation of the main wheel 2 can be prevented from being transmitted to the pinion gear 5.

Furthermore, 7 is an engaging claw provided to engage the recess 2b and the protrusion 5b, and 8 is an engagement disengagement claw provided to disengage the recess 2b and the protrusion 5b. By providing these claws 7 and 8, the recess 2b and the protrusion 5b can be engaged or disengaged, allowing for appropriate switching between transmission and non-transmission of the rotation of the main wheel 2 to the pinion gear 5.

(2) Operation Next, the operation of the wheel structure according to this embodiment from before contact with the step to after riding over the step will be described.

In the normal driving state, when traveling on a flat surface before contact with a step, the wheel structure, as shown in Figure 1, has the auxiliary wheels 3 lifted off the ground (not shown), and the main wheels 2 rotate counterclockwise, supporting the load applied via the cargo platform mounting portion 4, and moving forward to the left on the plane of the paper. At this time, the recess 2b and the protrusion 5b are disengaged by the engagement release claw 8, and the rotation of the main wheels 2 is not transmitted to the pinion gear 5.

Subsequently, the wheel structure moves forward to just before the step, and the main wheel contacts the step's end surface. Figure 4 is a schematic side view showing the state when the main wheel contacts the step's end surface. In Figure 4, 10 is the flat surface (during normal driving), 11 is the step, 11a is the step's end surface, and 11b is the step's top surface.

As shown in Figure 4, when the wheel structure moves forward along the flat surface 10 to just before the step 11 and the main wheel 2 contacts the step end surface 11a, the main wheel 2 stops rotating. At this time, the main wheel 2 receives a reaction force due to contact with the step end surface 11a, while the frame 1 moves forward due to the impact of the main wheel 2 hitting the step end surface 11a. As a result, the main wheel axle 2a moves rearward and downward within the short hole 6a.

Subsequently, when the main axle 2a, having moved through the short hole 6a, reaches the curved hole 6c, the pinion gear 5, which has moved with the main axle 2a, begins to mesh with the curved portion 9b of the rack gear 9 and starts rotating clockwise. As the pinion gear 5 rotates, the main axle 2a moves from the curved hole 6c to the long hole 6b. Afterward, the load applied via the transportable material mounting section 4 causes the pinion gear 5 to rotate and move upward and rearward along the long hole 6b.

Figure 5 is a schematic side view illustrating the state in which the pinion gear 5 is moving along the elongated hole 6b. At this time, as the pinion gear 5 rotates while meshing with the elongated portion 9a of the rack gear 9, the main wheel shaft 2a also moves rearward and upward along the elongated hole 6b. However, since the main wheel 2 is in contact with the flat surface 10, the frame 1 moves downward, causing the front auxiliary wheel 3 to come into contact with the stepped upper surface 11b. At this time, as described above, the recess 2b and the protrusion 5b are not engaged, so even though the pinion gear 5 is rotating, the main wheel 2 does not rotate, maintaining the state in which it was in contact with the stepped end surface 11a.

When the auxiliary wheel 3 contacts the upper surface 11b of the step, the majority of the load on the wheel structure is transferred to the auxiliary wheel 3, while the force on the main wheel 2 is limited to its own weight. As the main wheel axle 2a moves further upward and rearward, the main wheel 2 lifts slightly off the flat surface 10, and the force pushing the vehicle structure forward causes the main wheel 2 to resume rotation and attempt to ride up onto the upper surface 11b. At this point, the forces acting on the main wheel 2 consist of two components: the force lifting the main wheel 2 off the flat surface 10 and the force pushing the vehicle structure forward. It is easy to lift the light wheel.

Figure 6 is a schematic side view illustrating the state in which the main wheel 2 has ridden onto the stepped surface 11b. As shown in Figure 6, when the main wheel 2 rides onto the stepped surface 11b, the pinion gear 5 has reached the rear end of the elongated hole 6b. At this point, the tapered portion 5a of the pinion gear 5 is pressed towards the main wheel 2 by the engaging claw 7, causing the recess 2b and the convex portion 5b to engage, and the rotation of the main wheel 2 is transmitted to the pinion gear 5.

Figure 7 is a schematic perspective view illustrating the engagement between the recess 2b and the protrusion 5b. However, when the pinion gear 5 reaches the rear end of the elongated hole 6b, the positions of the recess 2b and the protrusion 5b are not necessarily the same (their phases are undefined). Therefore, as shown in Figure 7, the pinion gear 5 is rotated while being pressed against the main wheel 2 to move the protrusion 5b to the position of the recess 2b. When the recess 2b and the protrusion 5b are in the same position, they are engaged. This allows the rotation of the main wheel 2 to be transmitted to the pinion gear 5, enabling both the main wheel 2 and the pinion gear 5 to rotate in the same counterclockwise direction.

In Figures 3 and 7, two recesses 2b and two protrusions 5b are arranged in rotationally symmetrical positions so that they can engage with the main wheel 2 during a 1/2 rotation of the pinion gear 5. However, one may be used. Furthermore, three or more n protrusions may be arranged at equal angles; in this case, they can engage with the main wheel 2 during a 1/n rotation of the pinion gear 5. Also, either the recess 2b or the protrusion 5b can be a recess or a protrusion, as long as engagement is possible.

As described above, the engagement of the recess 2b and the protrusion 5b changes the state in which the rotation of the main wheel 2 is transmitted to the pinion gear 5. Then, the pinion gear 5 rotates counterclockwise, the same direction as the main wheel 2, and, while meshing with the elongated portion 9a of the rack gear 9, moves the hole 6 from the rear end of the elongated hole 6b toward the front and downward, reaching the curved hole 6c.

Figure 8 is a schematic side view illustrating the state when the pinion gear 5 reaches the curved hole 6c. As shown in Figure 8, the frame 1 and auxiliary wheel 3 rise to their initial positions as the pinion gear 5 moves into the curved hole 6c. In this case, the pinion gear 5 rotates approximately two times before reaching the curved hole 6c. That is, the main wheel 2 rotates approximately two times as it rises to an initial position close to the radius of the main wheel, resulting in a gradual rise. Upon reaching the curved hole 6c, the pinion gear 5 disengages from the rack gear 9. Subsequently, the load on the wheel structure causes the main wheel shaft 2a to move forward and upward within the short hole 6a to its initial position. Simultaneously, the engagement between the recess 2b and the protrusion 5b is disengaged by the engagement release claw 8, preventing the rotation of the main wheel 2 from being transmitted to the pinion gear 5, thus returning to the initial state.

Figure 9 is a schematic perspective view illustrating the release of engagement between the recess 2b and the protrusion 5b by the engagement release claw 8. The tip of the engagement release claw 8 enters the tapered gap in the engagement portion between the pinion gear 5, which moves forward and upward within the short hole 6a, and the main wheel 2, thereby releasing the engagement between the recess 2b and the protrusion 5b.

As described above, the wheel structure is able to overcome the step. In this embodiment, during the reciprocating movement in the hole of the main wheel axle, the transmission and non-transmission of the main wheel's rotation to the pinion gear are appropriately switched, so that two forces are applied to the main wheel 2: a force that lifts the main wheel 2 off the flat surface 10 and a force that moves the vehicle structure forward. This makes it easy to lift a light wheel.

(3) Modified Switching Mechanism In the above, the transmission and non-transmission of the rotation of the main wheel to the pinion gear is switched using the protrusions and recesses provided between the main wheel and the pinion gear, and the engaging and disengaging pawls. However, the following modified versions can also be used as the switching mechanism. Note that in each modified version, the configuration and operation other than the switching mechanism are basically the same as those described above, so only the explanation related to the switching mechanism is described below.

(a) Free-type bidirectional clutch (first modified example)
The first modification is an example in which a free-type bidirectional clutch provided between the main axle and the pinion gear is used as the switching mechanism.

A free-type bidirectional clutch has the characteristic of transmitting force applied to the input shaft to the output shaft, but not transmitting force applied to the output shaft to the input shaft. Therefore, even when a free-type bidirectional clutch is used as the switching mechanism instead of engagement and disengagement pawls, it is possible to switch between transmitting and not transmitting the rotation of the main wheel to the pinion gear. Using a free-type bidirectional clutch as the switching mechanism allows for a simpler wheel structure configuration and improved reliability.

Figure 10 is a schematic side view showing an example of a wheel structure using a free-type bidirectional clutch as a switching mechanism. In Figure 10, 13 is a free-type bidirectional clutch, positioned between the main wheel shaft 2a and the pinion gear 5, with the main wheel shaft 2a side acting as the input shaft.

During normal operation, the main wheel 2, which is the input shaft, rotates, moving the wheel structure forward, and at the same time, the pinion gear 5, which is the output shaft, also rotates. However, at this time, the pinion gear 5 is in the initial position of the short hole 6a and has not yet meshed with the rack gear 9, so it is in a state of free rotation relative to the rack gear 9.

Then, from the moment the main wheel 2 contacts the end face of the step until the auxiliary wheel 3 contacts the top surface of the step, the main wheel 2 remains stationary and in contact with the end face of the step, as described above (see Figures 4 and 5). Meanwhile, after moving to the curved hole 6c, the main wheel shaft 2a moves upward and rearward along the elongated hole 6b, in accordance with the movement of the pinion gear 5 within the hole 6 as it rotates while meshing with the elongated portion 9a of the rack gear 9. At this time, the pinion gear 5 rotates clockwise, opposite to the rotation direction of the main wheel 2, due to its meshing relationship with the rack gear 9. However, since the force applied to the output shaft (pinion gear 5) is not transmitted to the input shaft (main wheel 2) by the free-type bidirectional clutch 13, the main wheel 2 remains stationary.

Subsequently, the main wheel 2 resumes rotation to gain traction on the step surface 11b, but the pinion gear 5 (output shaft) maintains its rotation in the opposite direction to the main wheel 2 (input shaft). At this time, since (rotation angle of main wheel 2) < (rotation angle of pinion gear 5), relatively speaking, the output shaft (pinion gear 5) rotates relative to the input shaft (main wheel 2), and no force is transmitted from the output shaft to the input shaft.

After the main wheel 2 rides onto the upper surface 11b of the step, the rotation of the input shaft (main wheel 2) is transmitted to the output shaft (pinion gear 5) via the bidirectional clutch 13, causing the pinion gear 5 to rotate counterclockwise, the same direction as the main wheel 2. Then, the pinion gear 5, rotating counterclockwise, moves through the hole 6 while meshing with the rack gear 9, returning to its initial position as described above (see Figures 6 and 8).

(b) Combination of elastic body and locking part (second modified example)
A second modification is an example in which an elastic body is combined with the locking part of the main wheel and the locking part of the pinion gear to provide the same function as the free-type bidirectional clutch described above, and to serve as a switching means.

Figure 11 is a schematic perspective view illustrating the combination of this elastic body with the locking portion of the main wheel and the locking portion of the pinion gear. Figure 12 is a schematic perspective view illustrating the state of the main wheel and pinion gear during normal operation in this modified example, and Figure 13 is a schematic perspective view showing the state of the main wheel and pinion gear when the main wheel has driven onto the top surface of a step.

In Figures 11 to 13, 14 is an elastic body such as a torsion spring. As shown in Figure 11, one end 14a of the elastic body 14 is fixed to a fixing portion 5d provided on the pinion gear 5, and the other end 14b is fixed to a fixing portion 2d provided on the main wheel 2. It is positioned in a free state where no external force is acting, or in a state where it is biased counterclockwise. The locking portion 5e provided on the pinion gear 5 and the locking portion 2e provided on the main wheel 2 are configured to lock with each other.

As shown in Figure 12, during normal operation, the main wheel 2 and the pinion gear 5 are in surface contact.

After the main wheel contacts the stepped end surface, the rotation of the main wheel 2 remains stopped until the auxiliary wheel contacts the upper surface of the step, as described above (see Figures 4 and 5). Meanwhile, the pinion gear 5 rotates clockwise while meshing with the rack gear 9. As the pinion gear 5 rotates, the elastic body 14 is gradually compressed.

Subsequently, until the main wheel resumes rotation and rides up onto the step surface, the main wheel 2 rotates counterclockwise, while the pinion gear 5 rotates clockwise because it is meshed with the rack gear 9, similar to Figure 10. At this time, since (rotation angle of the main wheel) < (rotation angle of the pinion gear), the rotation of the main wheel 2 is not transmitted to the pinion gear 5. As the pinion gear 5 rotates clockwise, the locking portion 5e of the pinion gear 5 moves from a position behind the locking portion 2e of the main wheel 2 to a position in front of the locking portion 2e of the main wheel 2. Accordingly, the elastic body 14 is further compressed.

Subsequently, when the rotating locking portion 5e comes into contact with the locking portion 2e, the two locking portions 5e and 2e become locked, and the rotation of the main wheel 2 is transmitted to the pinion gear 5 via the two locking portions 5e and 2e, causing the main wheel 2 and the pinion gear 5 to rotate in the same counterclockwise direction. Then, as in Figure 10, the pinion gear 5 moves towards the initial position of the hole 6 while meshing with the rack gear 9, completing the ride-over process.

Thus, in this modified example, while employing a simple configuration using inexpensive and common components such as an elastic body and two locking parts, it is possible to appropriately switch between transmitting and not transmitting the rotation of the main wheel to the pinion gear. Therefore, it is possible to provide the same functionality as a free-type bidirectional clutch with high reliability and at a lower cost.

In Figures 11 to 13 above, the pinion gear 5 rotates slightly less than one full rotation relative to the main wheel 2, causing the two locking parts 5e and 2e to come into contact and lock. However, if a rotation range of more than one full rotation is required, this can be achieved by placing an intermediate rotating body between the main wheel and the pinion gear.

Figure 14 is a schematic perspective view showing a case where an intermediate rotating body 15 is positioned between the main wheel 2 and the pinion gear 5, as shown in Figures 11 to 13. In Figure 14, 15 is the intermediate rotating body, and the intermediate rotating body 15 is equipped with an elastic body 16. The main wheel 2 side of the intermediate rotating body 15 has a locking portion 15a that contacts the locking portion 2e, and the pinion gear 5 side has a locking portion 15b that contacts the locking portion 5e. Although not shown, the intermediate rotating body 15 is also provided with a fixing portion for fixing one end 14a of the elastic body 14 and one end of the elastic body 16, both attached to the main wheel 2. The other end of the elastic body 16 is fixed to the fixing portion 5d.

By providing such an intermediate rotating body 15, an additional rotation of slightly less than one full rotation can be achieved. Specifically, first, as the pinion gear 5 meshes with the rack gear and rotates, the locking portion 5e rotates in conjunction with it, contacting and engaging with the locking portion 15b. Then, as the pinion gear 5 rotates further, the intermediate rotating body 15 rotates together with the pinion gear 5 due to the locking portion 15b that has locked the locking portion 5e. In conjunction with this, the locking portion 15a rotates, contacting and engaging with the locking portion 2e. Thus, in this modified example, by providing an intermediate rotating body, the pinion gear can be rotated by slightly less than two full rotations. Based on this idea, if n intermediate rotating bodies are provided, an additional rotation of slightly less than n full rotations can be achieved.

(c) Symmetrical arrangement of pinion gear and rack gear (third modified example)
A third variation is an example in which the pinion gear and the rack gear are symmetrically arranged on both sides of the main wheel, along with the switching means described above.

In the first embodiment and its various modifications described above, the pinion gear, rack gear, and switching mechanism are described as being arranged on one side of the main wheel. However, they may also be arranged on both sides of the main wheel, symmetrically. In this case, it is preferable to provide a gear connecting section that links the pinion gears on both sides. This allows the pinion gears on both sides to rotate synchronously and in phase, thereby maintaining an appropriate balance of forces, stabilizing the overtaking operation, and enabling smoother overtaking of steps.

An example is shown in Figures 15 and 16. Figure 15 is a schematic cross-sectional view of the wheel structure with the configuration shown in Figures 1 and 2, where pinion gears, rack gears, etc., are arranged on both sides of the main wheel. Figure 16 is a schematic perspective view illustrating the gear coupling portion in Figure 15. In Figures 15 and 16, 12 represents the gear coupling portion. By engaging the protrusion 12a on the gear coupling portion 12 with the recess 5c on the pinion gear 5, the left and right pinion gears can be fixed and operated synchronously, and the main wheel 2 can be prevented from moving in the axial direction.

2. Second Embodiment (1) Configuration of Wheel Structure The wheel structure according to this embodiment, like the wheel structure according to the first embodiment, has a large-diameter main wheel, a small-diameter auxiliary wheel, and a frame provided with a transportable platform mounting section. After the main wheel makes contact with the step, the auxiliary wheel comes into contact with the upper surface of the step, causing the main wheel to ride up onto the upper surface of the step. The frame supports the auxiliary wheel at its front lower end, and the frame has a hole formed in which a short hole extending downward and rearward and a long hole extending upward and rearward are connected by a curved hole, through which the main wheel axle can be inserted. As the main wheel axle inserted into the hole moves through the hole, the main wheel rides up onto the upper surface of the step while forming a predetermined track. After that, the main wheel axle moves through the hole in the opposite direction to when it rode up, returning to the state before contact with the step, which is also the same as in the first embodiment.

However, this embodiment differs from the first embodiment in that the rack gear is positioned in front of the bore, a clutch gear capable of engaging with both the pinion gear and the rack gear is provided, and the transmission or non-transmission of the clutch gear's rotation to the pinion gear is switched using an elastic body connecting the clutch gear and the pinion gear.

Figure 17 is a schematic side view of the wheel structure according to this embodiment, and Figure 18 is a schematic front view of the same wheel structure. In Figures 17 and 18, 17 is a clutch gear, and 18 is an elastic body. As shown in Figures 17 and 18, the pinion gear 5 and the clutch gear 17 are connected by the elastic body 18, and the clutch gear 17 meshes with the rack gear 9. The pinion gear 5 is engaged with the main wheel shaft 2a and rotates together with the main wheel 2. The diameter of the pinion gear 5 is smaller than the diameter of the clutch gear 17 to avoid contact with the rack gear 9.

(2) Operation When the vehicle is traveling on a flat surface before contact with a step, as shown in Figure 17, the wheel structure has the auxiliary wheels 3 lifted off the ground, and the main wheels 2 rotate counterclockwise to move forward while supporting the load applied via the cargo platform mounting part 4. At this time, the clutch gear 17 is not engaged with the pinion gear 5, so the rotation of the main wheel shaft 2a and the pinion gear 5 is not transmitted to the clutch gear 17.

Subsequently, the wheel structure moves forward to just before the step, and the main wheel 2 contacts the step's end surface. At this point, similar to the first embodiment, the main wheel 2, having stopped rotating, receives a reaction force due to contact with the step's end surface 11a. Meanwhile, the frame 1 moves forward due to the impact of the main wheel 2 hitting the step's end surface 11a. As a result, the main wheel axle 2a moves rearward and downward within the short hole 6a.

As the main axle 2a moves through the short hole 6a and reaches the curved hole 6c, the load applied via the transport platform mounting section 4 causes the pinion gear 5, which has moved with the main axle 2a, to push upward the clutch gear 17, which is engaged with the rack gear 9, via the elastic body 18. As a result, the clutch gear 17 begins to rotate counterclockwise while engaging with the rack gear 9. Then, as the clutch gear 17 rotates, the main axle 2a moves from the curved hole 6c to the long hole 6b, and moves upward and rearward along the long hole 6b. Note that the clutch gear 17 is still not engaged with the pinion gear 5, so the rotation of the clutch gear 17 is not transmitted to the main axle 2a.

Figure 19 is a schematic side view illustrating the state in which the clutch gear 17 is engaged with the rack gear 9 and moving along the elongated hole 6b. At this time, as the pinion gear 5, which is pushing the clutch gear 17 via the elastic body 18, moves, the main wheel shaft 2a also moves rearward and upward along the elongated hole 6b. However, since the main wheel 2 is in contact with the flat surface 10, the frame 1 moves downward, causing the front auxiliary wheel 3 to come into contact with the stepped upper surface 11b. Note that the clutch gear 17 is still not engaged with the pinion gear 5; therefore, even though the clutch gear 17 is rotating, the main wheel shaft 2a and pinion gear 5 do not rotate and remain in the state in which they were in contact with the stepped end surface 11a, and their rotation has stopped.

When the auxiliary wheel 3 makes contact with the upper surface 11b of the step, the majority of the load on the wheel structure is transferred to the auxiliary wheel 3, while the force on the main wheel 2 is limited to its own weight. As the main wheel axle 2a moves further upward and rearward, the main wheel 2 lifts slightly off the flat surface 10, and the force pushing the vehicle structure forward causes the main wheel 2 to resume rotation and attempt to ride up onto the upper surface 11b of the step. At this point, the forces acting on the main wheel 2 consist of two parts: the force lifting the main wheel 2 off the flat surface 10 and the force pushing the vehicle structure forward. Therefore, the main wheel 2 can smoothly ride up onto the upper surface 11b, as if climbing a gentle slope.

Figure 20 is a schematic side view illustrating the state in which the main wheel 2 has ridden onto the upper surface 11b of the step. As shown in Figure 20, when the main wheel 2 rides onto the upper surface 11b of the step, the clutch gear 17 has reached the rear end of the elongated hole 6b. Therefore, if further load is applied to the main wheel 2 thereafter, the elastic body 18 will be pressed and compressed by the pinion gear 5. Finally, the pinion gear 5 and the clutch gear 17 mesh and engage.

When the pinion gear 5 and the clutch gear 17 engage, the rotation of the main wheel 2 and the pinion gear 5 is transmitted to the clutch gear 17. The clutch gear 17 then meshes with the pinion gear 5, reversing its rotation from counterclockwise to clockwise. Subsequently, while meshing with the elongated portion 9a of the rack gear 9, it moves through the hole 6 from the rear end of the elongated hole 6b downwards and forwards. Simultaneously, the pinion gear 5, moving through the hole 6, reaches the curved hole 6c, and at the same time, reaches its initial position near the curved hole 6c.

Figure 21 illustrates the state when the clutch gear 17 reaches its initial position near the curved hole 6c. Note that in Figure 21, the elastic body 18 is omitted to clearly show that the pinion gear 5 and the clutch gear 17 are engaged.

As shown in Figure 21, the main wheel 2 and pinion gear 5 move in conjunction with the clutch gear 17, causing the frame 1 and auxiliary wheel 3 to rise to their initial positions. Meanwhile, the pinion gear 5, upon reaching the curved hole 6c, disengages from the clutch gear 17 due to the restoring force of the compressed elastic body 18, returning to its initial state where the rotation of the main wheel shaft 2a and pinion gear 5 is not transmitted to the clutch gear 17. Subsequently, the load on the wheel structure causes the main wheel shaft 2a to move forward and upward within the short hole 6a, returning to its initial state.

As described above, the wheel structure is completed to climb over the step. In this embodiment, during the reciprocating movement in the hole of the main wheel axle, the transmission and non-transmission of the rotation of the main wheel and pinion gear to the clutch gear is appropriately switched, so that two forces are applied to the main wheel 2: a force that lifts the main wheel 2 off the flat surface 10 and a force that moves the vehicle structure forward. This allows the main wheel 2 to smoothly climb onto the upper surface 11b of the step, as if ascending a gentle slope.

3. Third Embodiment In the first and second embodiments described above, the main axle, which moves back and forth through the hole, is made to follow a predetermined trajectory, thereby enabling smooth riding onto the upper surface of the step in the vehicle structure with minimal force. However, in the third embodiment, the main axle is made to follow a predetermined trajectory without providing a hole, thereby enabling smooth riding onto the upper surface of the step in the vehicle structure with minimal force.

(1) Wheel Structure Configuration Figure 22 is a schematic side view of a wheel structure according to the third embodiment, and Figure 23 is a schematic front view of the same wheel structure. In Figures 22 and 23, 19 is the main wheel frame and 21 is the clutch gear frame, with one end of each being pivotally supported on a shaft 19a on which an elastic body 23 is provided. The shaft 19a is rotatably pivotally supported on the frame 1.

As shown in Figures 22 and 23, the wheel structure according to this embodiment, like the wheel structures according to the first and second embodiments, has a frame 1 equipped with a large-diameter main wheel 2, a small-diameter auxiliary wheel 3, and a transportable load platform mounting section 4. The configuration is such that after the main wheel 2 contacts the step, the auxiliary wheel 3 contacts the upper surface of the step, causing the main wheel 2 to ride up onto the upper surface.

However, in this embodiment, the frame 1 is provided with an elastic body 23, a main wheel frame stopper 20, a clutch gear frame stopper 22, and a rack gear 9.

The elastic body 23 is mounted on the shaft 19a and provides a biasing force to the main wheel frame 19 in the forward direction (to the left in the plane of the paper). It connects the main wheel frame 19 to the clutch gear frame 21, which has a clutch gear 17 at one end, thereby supporting the main wheel frame 19 and the clutch gear frame 21 so that they can rotate freely. The main wheel frame stopper 20 is provided to prevent the rotation of the main wheel frame 19 in the forward direction, and the clutch gear frame stopper 22 is provided to prevent the rotation of the clutch gear frame 21 in the forward direction.

Furthermore, a pinion gear 5 is provided at the other end of the main wheel frame 19 so as to rotate together with the main wheel 2 via the main wheel shaft 2a, and a clutch gear 17 is provided at the other end of the clutch gear frame 21 so as to mesh with the rack gear 9.

(2) Operation In the normal driving state when traveling on a flat surface before contact with a step, the wheel structure, as shown in Figure 22, has the auxiliary wheels 3 lifted off the ground, and the main wheels 2 move forward while supporting the load applied via the transport platform mounting part 4. At this time, the rotation of the main wheel frame 19 is stopped from moving forward by the main wheel frame stopper 20, and the rotation of the clutch gear frame 21 is stopped from moving forward by the clutch gear frame stopper 22, so the counterclockwise rotation of the main wheels 2 and pinion gear 5 is not transmitted to the clutch gear 17.

Subsequently, the wheel structure advances to just before the step, and the main wheel 2 contacts the step's end surface. Figure 24 is a schematic side view showing the state when the main wheel 2 contacts the step's end surface 11a. As shown in Figure 24, when the wheel structure advances along the flat surface 10 to just before the step 11 and the main wheel 2 contacts the step's end surface 11a, the main wheel 2 stops rotating. At this time, the main wheel 2 receives a reaction force due to contact with the step's end surface 11a, while the frame 1 moves forward due to the impact of the main wheel 2 hitting the step's end surface 11a. As a result, the main wheel axle 2a moves slightly backward (to the right of the paper), and in conjunction with this, the main wheel frame 19 rotates in an arc-shaped trajectory centered on the axle 19a.

Subsequently, when further forward force is applied to the wheel structure, the frame 1 moves forward while descending, and the front auxiliary wheel 3 comes into contact with the upper surface 11b of the step. Figure 25 is a schematic side view showing the state when the auxiliary wheel 3 is in contact with the upper surface 11b of the step. At this time, the main wheel frame stopper 20, which is positioned on the frame 1, also moves forward in accordance with the forward movement of the frame 1. However, since the main wheel 2 is stopped from moving forward by the step end surface 11a, the main wheel frame 19 rotates further backward, away from the main wheel frame stopper 20.

When the auxiliary wheel 3 contacts the upper surface 11b of the step, the majority of the load on the wheel structure is transferred to the auxiliary wheel 3, while the force on the main wheel 2 is limited to its own weight. Then, as the main wheel frame 19 rotates further, the main wheel 2 lifts slightly off the flat surface 10, and the force pushing the vehicle structure forward causes the main wheel 2 to resume rotation and attempt to ride up onto the upper surface 11b of the step. At this point, the forces acting on the main wheel 2 consist of two parts: the force lifting the main wheel 2 off the flat surface 10 and the force pushing the vehicle structure forward. It is easy to lift the light wheel. Then, the main wheel 2, which was in contact with the end surface 11a of the step, resumes rotation in the forward direction.

At this point, the clutch gear frame 21 is still locked in place by the clutch gear frame stopper 22, preventing the clutch gear 17 from moving from its initial position. Therefore, the angle between the main wheel frame 19 and the clutch gear frame 21 gradually decreases, and simultaneously, the elastic body 23 is compressed.

Subsequently, when further forward force is applied to the wheel structure, the main wheel 2 completely rides up onto the upper surface 11b of the step. Figure 26 is a schematic side view showing the state when the main wheel 2 has completely rides up onto the upper surface 11b of the step.

As shown in Figure 26, when the main wheel 2 rides onto the step surface 11b, the pinion gear 5, positioned at the tip of the rotating main wheel frame 19, reaches its rearmost and uppermost position. This initiates engagement between the pinion gear 5 and the clutch gear 17, and the rotation of the pinion gear 5 is transmitted to the clutch gear 17. Subsequently, in accordance with the counterclockwise rotation of the pinion gear 5, the clutch gear 17 rotates clockwise, opposite to the main wheel 2 and pinion gear 5, and moves downward along the rack gear 9.

Then, as the clutch gear 17 moves downward, the frame 1 rises. Figure 27 is a schematic side view illustrating this movement of the frame 1. As shown in Figure 27, as the frame 1 rises, the auxiliary wheels 3 move away from the step surface 11b and towards their initial position. At this time, the clutch gear frame 21 moves away from the clutch gear frame stopper 22, which was locking the movement of the clutch gear frame 21, in accordance with the downward movement of the clutch gear 17.

Subsequently, as the main wheel 2 rotates further, the state shown in Figure 28 is reached. Figure 28 is a schematic side view illustrating the state just before the frame 1 and auxiliary wheel 3 return to their initial positions. The main wheel frame 19 is positioned vertically to the shaft 19a, and the clutch gear 17 has moved to the lower end of the rack gear 9.

Here, when a load is applied to the vehicle structure via the cargo loading platform mounting section 4, the engagement between the pinion gear 5 and the clutch gear 17 is disengaged. Then, due to the restoring force of the compressed elastic body 23, the angle between the main wheel frame 19 and the clutch gear frame 21 returns to its original position. The main wheel frame 19 moves until it contacts the main wheel frame stopper 20, and the clutch gear frame 21 until it contacts the clutch gear frame stopper 22, returning to its initial position. Simultaneously, the clutch gear 17, now free from engagement with the pinion gear 5, rotates counterclockwise along the rack gear 9 as the clutch gear frame 21 moves, rising and returning to its initial position.

As described above, the wheel structure is able to overcome the step. In this embodiment, the relationship between the main wheel frame 19 and the main wheel frame stopper 20, and the relationship between the clutch gear frame 21 and the clutch gear frame stopper 22 are appropriately switched to form a trajectory on the main wheel 2 similar to that of the first and second embodiments. This creates two forces acting on the main wheel 2: a force that lifts the main wheel 2 off the flat surface 10, and a force that moves the vehicle structure forward. This makes it easy to lift a light wheel.

Furthermore, by appropriately adjusting the position of the shaft 19a in frame 1, the size of the main wheel frame 19, and the clutch gear frame 21, the vehicle structure can smoothly ride over steps higher than the radius of the main wheel 2, which was difficult to overcome in the first and second embodiments.

4. Fourth Embodiment In the first and second embodiments, since the pinion gear is provided on the main wheel axle to overcome steps, as described above, it is difficult to smoothly overcome steps that are higher than the radius of the main wheel.

Therefore, in the fourth embodiment, the concepts of the first and second embodiments are further developed by raising the mounting position of the pinion gear, so that the vehicle structure can smoothly ride over steps that are higher than the radius of the main wheel.

(1) Wheel Structure Configuration Figure 29 is a schematic side view of the wheel structure according to this embodiment, and Figure 30 is a schematic front view of the same wheel structure. Figure 31 is a schematic perspective view illustrating the rotation of the main wheel in this embodiment. Figure 32 is a schematic exploded perspective view illustrating the mounting of the main wheel in this embodiment. In Figures 29 to 32, 24 is the main wheel, 25 is the bearing, 26 is the gear, 27 is the internal gear, and 28 is the second hole. The second hole 28 is formed in the same shape as the hole 6.

As shown in Figures 29 to 32, the wheel structure according to this embodiment, similar to the wheel structures shown in the first and second embodiments, has a frame 1 equipped with a large-diameter main wheel 2, a small-diameter auxiliary wheel 3, and a transportable load platform mounting portion 4. The configuration is such that after the main wheel 2 contacts the step, the auxiliary wheel 3 contacts the upper surface of the step, causing the main wheel 2 to ride up onto the upper surface.

However, in this embodiment, unlike the first to third embodiments in which the main wheel is supported by the main wheel axle, the main wheel 2 is supported by four support columns 24a to 24d provided on the main wheel 24.

Specifically, the inner surface of the main wheel 2 has a smooth area where bearings 25, which are rotatably inserted into each of the support columns 24a to 24d, make contact, and an area where an internal gear 27 that meshes with a gear 26 attached to the end of the bearing 25 on support column 24a is provided (see Figure 31). The rotation of each bearing 25 supports the rotation of the main wheel 2. Support columns 24a and 24b extend to the back side of the main wheel 24, with support column 24a inserted into the hole 6 and support column 24b inserted into the second hole 28. The tip of support column 24a has a protruding portion that can engage with the protruding portion of the pinion gear 5.

(2) Operation The operation of the wheel structure according to this embodiment is basically the same as that of the first and second embodiments in that the pinion gear 5 moves within the hole 6 to overcome the step.

In the normal driving state, when traveling on a flat surface before contact with a step, the wheel structure, as shown in Figure 29, has the auxiliary wheels 3 supported by the frame 1 floating, while the main wheels 2 support the load applied via the cargo platform mounting section 4, moving forward. At this time, the pinion gear 5 and gear 26 are disengaged by the engagement release pawl 8, and the rotation of the support column 24a is not transmitted to the pinion gear 5.

Subsequently, the wheel structure advances to just before the step, and the main wheel 2 contacts the step end surface 11a. Figure 33 is a schematic side view showing the state when the main wheel 2 contacts the step end surface 11a. As shown in Figure 33, when the wheel structure advances along the flat surface 10 to just before the step 11 and the main wheel 2 contacts the step end surface 11a, the main wheel 2 stops rotating and moves slightly backward due to the reaction force from contact with the step end surface 11a. In conjunction with this, the support column 24a moves backward and downward within the hole 6, and the support column 24b also moves backward and downward within the second hole 28.

As the main wheel axle 2a moves through the short hole 6a and reaches the curved hole 6c, the pinion gear 5 begins to engage with the curved portion 9b of the rack gear 9 and starts to rotate. In conjunction with this, the support column 24a moves from the curved hole 6c to the long hole 6b. Subsequently, due to the load applied via the transportable material mounting section 4, the pinion gear 5 rotates while engaging with the long portion 9c of the rack gear 9, moving upward and rearward along the long hole 6b. Then, in accordance with the movement of the support column 24a, the support column 24b also moves through the second hole 28. Note that at this time, the pinion gear 5 and gear 26 are not engaged; therefore, even though the pinion gear 5 is rotating, the main wheel 2 does not rotate.

Figure 34 is a schematic side view showing the state when the main wheel has completely driven onto the upper surface of the step in this embodiment, and Figure 35 is a schematic cross-sectional view of the wheel structure at that time. When the support column 24a reaches the rear upper end of the hole 6, similar to the first embodiment, the pinion gear 5 is pressed against the engaging claw 7, causing the pinion gear 5 and gear 26 to engage, and the rotation of the main wheel 2 is transmitted to the pinion gear 5.

Then, similar to the first embodiment, the pinion gear 5 rotates counterclockwise, the same direction as the main wheel 2, and, while meshing with the rack gear 9, descends through the hole 6 to its initial position. Simultaneously, the support column 24b also descends through the second hole 28 to its initial position, while the frame 1 rises.

Figure 36 is a schematic side view illustrating the movement of this frame. As frame 1 rises, the auxiliary wheels 3 move away from the upper surface 11b of the step and towards their initial position.

Then, as the pinion gear 5 descends further within the hole 6, the engagement between the pinion gear 5 and the gear 26 is released by the engagement release claw 8, similar to the first embodiment. This prevents the rotation of the main wheel 2 from being transmitted to the pinion gear 5, and the main wheel 2 returns to its initial state.

In this embodiment, instead of using the main axle, the vehicle overcomes obstacles by inserting support columns, which support the main wheels at a higher position than the main axle, into each hole and moving them. Therefore, even higher obstacles can be easily overcome with minimal force.

Although the above explanation described two holes, three or more holes may be provided. Similarly, although four support columns were described, three or more support columns may be used if support is possible through two or more holes.

Although the present invention has been described above based on embodiments, the present invention is not limited to the above embodiments. Various modifications can be made to the above embodiments within the same and equivalent scope as the present invention.

1 Frame 2 Main wheel 2a Main wheel axle 2b Recess 2d Fixing part 2e Locking part 3 Auxiliary wheel 4 Carrying platform mounting part 5 Pinion gear 5a Taper 5b Protrusion 5c Recess 5d Fixing part 5e Locking part 6 Hole 6a Short hole 6b Long hole 6c Curved hole 7 Engaging claw 8 Disengaging claw 9 Rack gear 9a Long section 9b Curved section 10 Flat surface 11 Step 11a Step end surface 11b Step top surface 12 Gear connecting part 12a Protrusion 13 (Free type) Bidirectional clutch 14 Elastic body 14a One end of elastic body 15 Intermediate rotating body 15a, 15b Locking part 16 Elastic body 17 Clutch gear 18 Elastic body 19 Main wheel frame 19a Shaft 20, Main wheel frame stopper 21, Clutch gear frame 22, Clutch gear frame stopper 23, Elastic body 24, Main wheel 24a-24d, Support column 25, Bearing 26, Gear 27, Internal gear 28, Second hole

Claims (8)

A wheel structure having a large-diameter main wheel, a small-diameter auxiliary wheel, and a frame provided with a transport platform mounting section, wherein after the main wheel contacts a step, the auxiliary wheel contacts the upper surface of the step, and the main wheel rides up onto the upper surface of the step,
The frame supports the auxiliary wheel at its front lower end,
The frame has a hole formed in which a short hole extending downward and rearward and a long hole extending upward and rearward are connected by a curved hole, allowing the main wheel axle to be inserted.
A pinion gear is provided on the main wheel shaft via a switching mechanism that can switch between transmitting and not transmitting the rotation of the main wheel.
The frame is provided with a rack gear that can mesh with the pinion gear, extending from the curved portion of the hole to the elongated portion of the hole, along the rear side of the hole.
As the main wheel axle inserted through the hole moves through the hole, the main wheel rides up onto the step surface while forming a predetermined track.
A wheel structure characterized in that the main axle is configured to return to its state before contact with the step by moving the hole in the opposite direction to when it is driven over. As a means for transmitting the rotation of the main wheel, the main wheel and the pinion gear are each provided with interlocking protrusions and recesses.
The wheel structure according to claim 1 , characterized in that the switching means is composed of an engaging claw for engaging the uneven portion and an engagement disengaging claw for disengaging the uneven portion. The wheel structure according to claim 1 , characterized in that the switching means is a free-type bidirectional clutch provided between the main wheel axle and the pinion gear. The wheel structure according to claim 1, characterized in that the switching means comprises an elastic body with one end fixed to the main wheel and the pinion gear, and a locking portion for rotation transmission provided on the main wheel and the pinion gear, respectively. The wheel structure according to claim 4 , characterized in that one or more intermediate rotating bodies, each having a locking portion for rotational transmission, are arranged between the main wheel and the pinion gear. The wheel structure according to any one of claims 1 to 5 , characterized in that the pinion gear and the rack gear are provided in pairs, symmetrically on both sides, so as to sandwich the main wheel and operate in synchronous motion. A wheel structure having a large-diameter main wheel, a small-diameter auxiliary wheel, and a frame provided with a transport platform mounting section, wherein after the main wheel contacts a step, the auxiliary wheel contacts the upper surface of the step, and the main wheel rides up onto the upper surface of the step,
The frame supports the auxiliary wheel at its front lower end,
The frame has a hole formed in which a short hole extending downward and rearward and a long hole extending upward and rearward are connected by a curved hole, allowing the main wheel axle to be inserted.
The main wheel shaft is provided with a pinion gear that rotates together with the main wheel.
A rack gear is provided on the front side of the hole, along the hole,
A clutch gear is provided so as to mesh with the rack gear and move from the curved portion of the hole to the elongated portion of the hole.
An elastic body connected between the clutch gear and the pinion gear allows for switching between transmitting and not transmitting the rotation of the main wheel to the pinion gear .
As the main wheel axle inserted through the hole moves through the hole, the main wheel rides up onto the step surface while forming a predetermined track.
A wheel structure characterized in that the main axle is configured to return to its state before contact with the step by moving the hole in the opposite direction to when it is driven over . A wheel structure having a large-diameter main wheel, a small-diameter auxiliary wheel, and a frame provided with a transport platform mounting section, wherein after the main wheel contacts a step, the auxiliary wheel contacts the upper surface of the step, and the main wheel rides up onto the upper surface of the step,
The inner circumferential surface of the main wheel has a smooth surface area in which bearings, which are rotatably inserted through each of the three or more support columns provided on the main wheel, make contact, and a region where an internal gear is provided that meshes with a gear attached to the end of one of the bearings on the support column. The main wheel is supported by the rotation of each of the bearings on the support column.
The frame supports the auxiliary wheel at its front lower end,
The frame has two or more parallel rows of holes, each having a shape in which a short hole extending downward and a long hole extending upward and rear are connected by a curved hole.
As the support columns inserted through each of the holes move through the holes, the main wheel rides up onto the step surface while forming a predetermined track.
A wheel structure characterized in that the main axle is configured to return to its state before contact with the step by moving the hole in the opposite direction to when it is driven over.