four-wheel drive

Abstract

To provide a four-wheel travel device with a novel steering mechanism.SOLUTION: A four-wheel travel device performs steering by converting telescopic motions of one linear actuator into rotational motions within horizontal planes of first and second front wheels and first and second rear wheels via a linkage. The linear actuator extends and contracts parallel to a line connecting between the first and second front wheels.SELECTED DRAWING: Figure 3A

Description

[Technical Field]

[0001] The present invention relates to a four-wheel traveling device. [Background technology]

[0002] Patent Document 1 discloses a steering device for a traveling vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4109361 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a four-wheel traveling device having a new steering mechanism. [Means for solving the problem]

[0005] According to one aspect of the present invention, there is provided a four-wheeled traveling device that performs steering by converting the extension and contraction movement of one linear actuator into rotational movement in a horizontal plane of a first front wheel, a second front wheel, a first rear wheel, and a second rear wheel via links, wherein the linear actuator extends and contracts parallel to a line connecting the first front wheel and the second front wheel.

[0006] Here, the first front wheel, the second front wheel, the first rear wheel, and the second rear wheel are, for example, the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel, respectively. The linear actuator expands and contracts parallel to the line connecting the left front wheel and the right front wheel, thereby making it possible to make the four-wheel traveling device smaller.

[0007] According to one aspect of the present invention, there is provided a four-wheeled traveling device that performs steering by converting the extension and contraction movement of one linear actuator into rotational movement in a horizontal plane of a first front wheel, a second front wheel, a first rear wheel, and a second rear wheel via links, wherein at least two of the link for the first front wheel, the link for the second front wheel, the link for the first rear wheel, and the link for the second rear wheel have the same shape.

[0008] The link for the first front wheel, the link for the second front wheel, the link for the first rear wheel, and the link for the second rear wheel may all have the same shape.

[0009] Here, the first front wheel, second front wheel, first rear wheel, and second rear wheel are, for example, the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively. By making at least two (preferably all four) of the links for the left front wheel, right front wheel, left rear wheel, and right rear wheel the same shape, manufacturing costs can be reduced.

[0010] According to one aspect of the present invention, there is provided a four-wheeled traveling device that performs steering by converting the extension and contraction movement of one linear actuator into rotational movement of a first front wheel, a second front wheel, a first rear wheel, and a second rear wheel in a horizontal plane via links, wherein the link for the first front wheel and the link for the first rear wheel are approximately in a first horizontal plane and rotate in the first horizontal plane, and the link for the second front wheel and the link for the second rear wheel are approximately in a second horizontal plane and rotate in the second horizontal plane, and the first horizontal plane and the second horizontal plane are different.

[0011] Here, the first front wheel, the second front wheel, the first rear wheel, and the second rear wheel are, for example, the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel, respectively. By making the link for the left front wheel and the link for the left rear wheel rotate in the same horizontal plane and the link for the right front wheel and the link for the right rear wheel rotate in another same horizontal plane, the four-wheel traveling device can be made smaller.

[0012] The four-wheel running device comprises the first front wheel, the second front wheel, the first rear wheel located behind the first front wheel, the second rear wheel located behind the second front wheel, the linear actuator, and the links, and the links may include a first link for the first front wheel, a second link for the second front wheel, a third link for the first rear wheel, and a fourth link for the second rear wheel.

[0013] The linear actuator has a rod that expands and contracts in a predetermined direction, and the four-wheel running device includes a bridge that moves in the predetermined direction in conjunction with the rod, and the first link and the third link rotate in a horizontal plane in conjunction with the expansion and contraction of the linear actuator by a first shaft provided on the rod, and the second link and the fourth link rotate in a horizontal plane in conjunction with the expansion and contraction of the linear actuator by a second shaft provided on the bridge.

[0014] The first link and the third link may each be provided with a slit, and the first shaft may be slidably fitted into the slits of the first link and the third link.

[0015] The second link and the fourth link may each be provided with a slit, and the second shaft may be slidably fitted into the slits of the second link and the fourth link.

[0016] The slit may extend parallel to a line connecting the first front wheel and the first rear wheel when the vehicle is traveling straight.

[0017] Each of the first to fourth links may have a small hole into which a third shaft that is not linked to the rod is fitted, and each of the first to fourth links may rotate in a horizontal plane around the small hole.

[0018] The linear actuator is positioned closer to the first front wheel and the first rear wheel than a line connecting the centers of the first front wheel and the second front wheel and the center of the first rear wheel and the second rear wheel, and when the rod of the linear actuator is in a reference position, the four-wheel running device moves straight, when the rod of the linear actuator extends from the reference position, the four-wheel running device bends toward the second front wheel and the second rear wheel, and when the rod of the linear actuator retracts from the reference position, the four-wheel running device bends toward the first front wheel and the first rear wheel.

[0019] As a specific example, the linear actuator may be positioned on the left side, and when the rod of the linear actuator is in a reference position, the four-wheel running device may move straight, when the rod of the linear actuator extends to the right from the reference position, the four-wheel running device may turn to the right, and when the rod of the linear actuator retracts to the left from the reference position, the four-wheel running device may turn to the left.

[0020] The four-wheel traveling device may include a camera and a controller that automatically controls the extension and contraction of the linear actuator based on an image from the camera. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 2 is a diagram schematically showing map information. [Figure 2] FIG. 2 is a functional block diagram of a four-wheel traveling device according to one embodiment. [Figure 3A] 1 is a schematic top view of a main part of a four-wheel traveling device according to one embodiment (when traveling straight). [Figure 3B] 1 is a schematic top view of a main part of a four-wheel traveling device according to one embodiment (when turning right). [Figure 3C] 1 is a schematic top view of a main part of a four-wheel traveling device according to one embodiment (when turning left). [Figure 4A] Schematic top view of floor plate 2, actuator 3, floor plate 2, bridge 4 and mount 5 (straight ahead). [Figure 4B]Schematic top view of floor plate 2, actuator 3, floor plate 2, bridge 4 and mount 5 (right turn). [Figure 4C] Schematic top view of floor plate 2, actuator 3, floor plate 2, bridge 4 and mount 5 (when turning left). [Figure 5A] Schematic perspective view of the floor plate 2, actuator 3, floor plate 2, bridge 4 and mount 5 (when traveling straight). [Figure 5B] Schematic perspective view of floor plate 2, actuator 3, floor plate 2, bridge 4 and mount 5 (when turning right). [Figure 5C] Schematic perspective view of floor plate 2, actuator 3, floor plate 2, bridge 4 and mount 5 (when turning left). [Figure 6A] Schematic perspective view of link 6FL, tie rod 7FL, and knuckle 8FL for left front wheel 1FL (when driving straight). [Figure 6B] Schematic perspective view of link 6FL, tie rod 7FL, and knuckle 8FL for left front wheel 1FL (when turning right). [Figure 6C] Schematic perspective view of link 6FL, tie rod 7FL, and knuckle 8FL for left front wheel 1FL (when turning left). [Figure 7] 1 is a schematic perspective view of a motor 10FL, a gearbox 11FL, a kingpin 12FL, a suspension arm 13FL, and a suspension 14FL for a left front wheel 1FL. [Figure 8] 3 is a diagram showing a schematic diagram of the relationship between the extension and contraction of the rod 32 and the traveling direction of the four-wheel traveling device. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0023] In this embodiment, a four-wheel traveling device that moves independently based on map information is exemplified. As shown in Fig. 1, the map information includes a starting point S, a destination G, and position information of markers M1 to M3 (for example, AR markers) that are installed in advance on walls, ceilings, floors, etc. These markers are used by the four-wheel traveling device to determine its own position.

[0024] 2 is a functional block diagram of a four-wheel traveling device according to one embodiment. The four-wheel traveling device includes a camera 100, a memory 101, a controller 102, a tablet terminal 103, an electric linear actuator 3, and wheels 1 (a collective term for a left front wheel, a right front wheel, a left rear wheel, and a right rear wheel).

[0025] Cameras 100 are provided on the front, rear, left and right sides of the four-wheel traveling device. Map information (FIG. 1) that can be set by the user via a tablet terminal 103 serving as a user interface is stored in memory 101. Controller 102 performs steering based on the image from camera 100 and the map information. Specifically, controller 102 detects markers M1 to M3 in the map information from the image from camera 100 and determines the current position of the four-wheel traveling device. Then, controller 102 controls the direction of wheels 1 by extending and retracting electric linear actuator 3 so that the four-wheel traveling device travels from departure point S to destination G.

[0026] For example, in FIG. 1, when marker M1 is detected in the image from camera 100 provided on the front, controller 102 determines that its own position is P1. Then, controller 102 steers the four-wheel traveling device so that it turns right. Thereafter, when marker M2 is detected in the image from camera 100 provided on the front and marker M3 is detected in the image from camera 100 provided on the right side, controller 102 determines that its own position is P2. Then, controller 102 steers the four-wheel traveling device so that it turns left. In this way, the four-wheel traveling device travels by itself from departure point S to destination G.

[0027] Alternatively, the four-wheel driving device may be provided with distance measuring sensors such as ultrasonic sensors or lasers (for example, in three locations on the front, left side, and right side), so that the movement of the four-wheel driving device is stopped if an object is detected nearby.

[0028] 3A to 3C are schematic top views of the main parts of a four-wheel traveling device according to one embodiment. Fig. 3A shows the device going straight, Fig. 3B shows the device turning right, and Fig. 3C shows the device turning left. Note that although these are called main parts, they are not essential and may be omitted or modified as appropriate.

[0029] This four-wheel traveling device has four wheels consisting of a left front wheel 1FL, a right front wheel 1FR, a left rear wheel 1RL, and a right rear wheel 1RR, which may be collectively referred to as "wheels 1." The four-wheel traveling device also has a front frame body 201, a central frame body 202, and a rear frame body 203, which may be collectively referred to as "main body 200."

[0030] When traveling straight, the line connecting the centers of the left front wheel 1FL and the right front wheel 1FR and the line connecting the centers of the left rear wheel 1RL and the right rear wheel 1RR are parallel to each other. Hereinafter, for convenience, this direction may be referred to as the x direction. Also, the line connecting the centers of the left front wheel 1FL and the left rear wheel 1RL and the line connecting the centers of the right front wheel 1FR and the right rear wheel 1RR are parallel to each other. Hereinafter, for convenience, this direction may be referred to as the y direction. The x direction and the y direction are perpendicular to each other.

[0031] As shown in FIG. 3A, when traveling straight, the front left wheel 1FL, front right wheel 1FR, rear left wheel 1RL, and rear right wheel 1RR are all parallel to the y direction.

[0032] As shown in Fig. 3B, when turning right, the left front wheel 1FL and the right front wheel 1FR face right relative to the body 200, and the left rear wheel 1RL and the right rear wheel 1RR face left relative to the body 200. In other words, the left front wheel 1FL and the right front wheel 1FR rotate clockwise in a horizontal plane, while the left rear wheel 1RL and the right rear wheel 1RR rotate counterclockwise in a horizontal plane.

[0033] As shown in Fig. 3C, when turning left, the left front wheel 1FL and the right front wheel 1FR face left relative to the body 200, and the left rear wheel 1RL and the right rear wheel 1RR face right relative to the body 200. In other words, the left front wheel 1FL and the right front wheel 1FR rotate counterclockwise in a horizontal plane, while the left rear wheel 1RL and the right rear wheel 1RR rotate clockwise in a horizontal plane.

[0034] One feature of this embodiment is that such steering for going straight, turning right, and turning left is performed using one electric linear actuator 3 (linear cylinder), more specifically, the linear motion of one electric linear actuator 3 is converted into rotational motion in a horizontal plane of the left front wheel 1FL, the right front wheel 1FR, the left rear wheel 1RL, and the right rear wheel 1RR. The mechanism for performing this steering will now be described.

[0035] As shown in schematic top views in Figure 4A (when going straight), Figure 4B (when turning right) and Figure 4C (when turning left), and schematic oblique views in Figure 5A (when going straight), Figure 5B (when turning right) and Figure 5C (when turning left), this four-wheel traveling device comprises a floor plate 2, an electric linear actuator 3 (hereinafter simply referred to as "actuator 3"), a steering link bridge 4 (hereinafter simply referred to as "bridge 4"), and two steering link mounts 5F, 5R (hereinafter simply referred to as "mounts 5F, 5R").

[0036] The floor plate 2 is fixed to a central frame 202 (not shown in FIG. 4, see FIG. 3A) of the four-wheel traveling device. In addition, a linear guide 21 extending in the x direction and an actuator mount 22 are fixedly disposed on the floor plate 2.

[0037] The actuator 3 is fixed onto the floor plate 2. More specifically, the actuator 3 has a main body 31 fixed onto the actuator mount 22 on the left side of the floor plate 2, and a rod 32 that extends and retracts in the x direction. It is desirable that the extension and retraction of the rod 32 be controlled automatically (without instructions from an operator) by a controller 102 based on the image from the camera 100. An upward-facing shaft 33 and a downward-facing connecting member 34 are provided near the tip of the rod 32.

[0038] It is desirable for the rod 32 to extend and retract in the x direction (in a horizontal plane) rather than in a diagonal direction, which allows the four-wheel traveling device to be made smaller. As will be described later, the rod 32 is in a predetermined reference position (for example, halfway between its most extended state and its most retracted state) when traveling straight, and extends to the right in the x direction from the reference position when turning right, and retracts to the left in the x direction from the reference position when turning left.

[0039] The bridge 4 extends in the x direction. The vertical cross section of the bridge 4 is a downward U-shape. The bridge 4 is disposed so as to cover the linear guide 21 of the floor plate 2 (to fit into the linear guide 21).

[0040] 5A and other figures, the left side of the bridge 4 is connected to the rod 32 of the actuator 3 via a connecting member 34. Therefore, the bridge 4 moves left and right (x direction) along the linear guide 21 in conjunction with the extension and contraction of the rod 32.

[0041] An upward-facing shaft 41 is provided on the right side of the bridge 4. As shown in FIG. 5A and other figures, it is desirable that the upper end of this shaft 41 is not at the same height as the upper end of the shaft 33 of the rod 32, and in this embodiment, it is at a lower position. Furthermore, the shaft 41 of the bridge 4 is located to the right of the shaft 33 of the rod 32. In other words, the shaft 33 corresponds to the left front wheel 1FL and the left rear wheel 1RL, and the shaft 41 corresponds to the right front wheel 1FR and the right rear wheel 1RR.

[0042] The mounts 5F, 5R are fixed on the floor plate 2 and are not linked to the extension and retraction of the rod 32. As shown in FIG. 4A etc., two shafts 51FL, 51FR corresponding to the left front wheel 1FL and the right front wheel 1FR are provided on the front (front wheel) mount 5F. In this embodiment, since the upper end of the shaft 33 of the rod 32 is lower than the upper end of the shaft 41 of the bridge 4, it is desirable that the shaft 51FL corresponding to the left front wheel 1FL is higher than the shaft 51FR corresponding to the right front wheel 1FR. Specifically, the shaft 51FL is approximately the same height as the shaft 33, and the shaft 51FR is approximately the same height as the shaft 41.

[0043] Similarly, two shafts 51RL and 51RR corresponding to the left rear wheel 1RL and the right rear wheel 1RR are provided on the rear mount 5R (for the rear wheels). In this embodiment, since the upper end of the shaft 33 of the rod 32 is lower than the upper end of the shaft 41 of the bridge 4, it is desirable that the shaft 51RL corresponding to the left rear wheel 1RL is higher than the shaft 51RR corresponding to the right rear wheel 1RR. Specifically, the shaft 51RL is approximately the same height as the shaft 33, and the shaft 51RR is approximately the same height as the shaft 41.

[0044] The steering link plates 6FL, 6FR, 6RL, and 6LL (hereinafter simply referred to as "links 6FL, 6FR, 6RL, and 6LL") shown in Figures 4A to 4C and Figures 5A to 5C will be described with reference to the following Figures 6A to 6C.

[0045] This four-wheel traveling device also includes four links 6FL, 6FR, 6RL, and 6LL, four tie rods 7FL, 7FR, 7RL, and 7LL, four knuckles 8FL, 8FR, 8RL, and 8LL, and four joints 9FL, 9FR, 9RL, and 9RR, each corresponding to one wheel. Schematic perspective views of components related to the left front wheel 1FL are shown in FIG. 6A (when traveling straight), FIG. 5B (when turning right), and FIG. 5C (when turning left). In this specification, the suffixes FL, FR, RL, and RR refer to the left front wheel 1FL, right front wheel 1FR, left rear wheel 1RL, and right rear wheel 1RR, respectively. When suffixes such as FL are not added, such as in the case of "link 6," the term refers collectively to the individual components.

[0046] The left side of the link 6FL has two small holes (a rear small hole 61FL and a front small hole 62FL) that are aligned in the y direction when traveling straight. The shaft 51FL of the mount 5F is rotatably fitted into the rear small hole 61FL via a bearing 64FL. One end of the tie rod 7FL is fitted into the front small hole 62FL via a bearing 65FL (preferably a rod end bearing).

[0047] Furthermore, a slit 63FL (long hole) that extends in the y direction when moving straight is provided on the right side of the link 6FL. The shaft 33 of the rod 32 fits into the slit 63FL. The shaft 33 can slide within the slit 63FL in conjunction with the extension and contraction movement of the rod 32. This allows the link 6FL to rotate within a horizontal plane via the shaft 33 in conjunction with the extension and contraction of the actuator 3.

[0048] The link 6FL (in cooperation with a tie rod 7FL and a knuckle 8FL, which will be described later) converts the linear movement (expansion and contraction) of the actuator 3 in the x direction into rotational movement of the left front wheel 1FL in a horizontal plane.

[0049] The tie rod 7FL is a rod-shaped member, the right end of which fits into a small hole 62FL in the link 6FL, and the left end of which fits into a small hole 81FL in the knuckle 8FL (described later) via a bearing 71FL. When traveling straight, the tie rod 7FL is not parallel to the x direction, and the knuckle 8FL side (left side) is positioned forward of the link 6FL side (right side).

[0050] The knuckle 8FL has a small hole 81FL at its right end, into which the left end of the tie rod 7 is fitted via a bearing 71FL. The left side of the knuckle 8FL is connected to a joint 9FL.

[0051] The joint 9FL is located rearward of the center of the left front wheel 1FL. The rear side of the joint 9FL is connected to the knuckle 8FL. The joint 9FL is also provided with a small hole 91FL. As will be described later with reference to Figure 6, the joint 9FL is connected to the front frame 201 via another member.

[0052] The above has been an explanation of the link 6FL, tie rod 7FL, knuckle 8FL, and joint 9FL for the left front wheel 1FL, but the same is true for the left rear wheel 1RL, right front wheel 1FR, and right rear wheel 1RR. However, shaft 41 of bridge 4, rather than shaft 33 of rod 32, is slidably fitted into slits 63FR, 63RR of links 6FR, 6RR for right front wheel 1FR and right rear wheel 1RR. As a result, links 6FR, 6RR rotate in a horizontal plane via shaft 41 in conjunction with the extension and contraction of actuator 3.

[0053] As shown in Figures 4A to 4C and 5A to 5C, the link 6RL for the left rear wheel 1RL is positioned over the link 6FL for the left front wheel 1FL. Therefore, the latter is positioned slightly higher (by the thickness of the link 6FL). In other words, these links 6FL and 6RL are on approximately the same horizontal plane. As shown in Figure 4A, when traveling straight, the slit 63FL of the link 6FL approximately overlaps with the slit 63RL of the link 6RL.

[0054] Similarly, the link 6RR for the right rear wheel 1RR is placed on top of the link 6FR for the right front wheel 1FR, that is, these links 6FR, 6RR are on approximately the same horizontal plane.

[0055] The upper end of the shaft 41 of the bridge 4 is located higher than the upper end of the shaft 33 of the rod 32. Therefore, as shown in FIG. 5A, the links 6FL, 6RL into which the shaft 33 is fitted are located higher than the links 6FR, 6RR into which the shaft 41 is fitted. In this way, it is desirable that the links 6FL, 6RL and the links 6FR, RR are offset from each other in the height direction. This allows the links 6FL, 6RL and the links 6FR, RR to rotate in different horizontal planes. Therefore, even if the links 6FL, 6RL and the links 6FR, RR are arranged adjacent to each other, they do not interfere with each other when turning right or left, and the four-wheel traveling device can be made smaller.

[0056] To reduce manufacturing costs, it is desirable that the link 6FL for the left front wheel 1FL be the same shape as the link 6FR for the right front wheel 1FR. Similarly, it is desirable that the link 6RL for the left rear wheel 1RL be the same shape as the link 6RR for the right rear wheel 1RR. Note that the term "same shape" does not necessarily mean that they must be exactly the same, but rather that they can be manufactured using the same process.

[0057] Furthermore, it is desirable that the link 6RL for the left rear wheel 1RL has a shape that is the inverse of the link 6FL for the left front wheel 1FL with respect to the x direction (or that the same shape can be used upside down). It is desirable that the link 6RR for the right rear wheel 1RR has a shape that is the inverse of the link 6FR for the right front wheel 1FR with respect to the x direction (or that the same shape can be used upside down). In other words, all four links 6 may have the same shape, or at least two of the four may have the same shape. This reduces manufacturing costs compared to when all four have different shapes. It is also desirable that the links 6, tie rods 7, and knuckles 8 are arranged symmetrically in the front and rear directions with the rod 32 as the axis when traveling straight.

[0058] This four-wheel traveling device also includes four motors 10FL, 10FR, 10RL, and 10RR, each corresponding to a wheel, gearboxes 11FL, 11FR, 11RL, and 11RR, kingpins 12FL, 12FR, 12RL, and 12RR, suspension arms 13FL, 13FR, 13RL, and 13RR, and suspensions 14FL, 14FR, 14RL, and 14RR. A schematic perspective view of the components related to the left front wheel 1FL is shown in FIG. 7.

[0059] The output shaft of the motor 10FL is connected to a gearbox 11FL, and the output shaft of the gearbox 11FL is connected to the left front wheel 1FL. The rotation of the motor 10FL is reduced at a predetermined ratio by the gearbox 11FL and transmitted to the left front wheel 1FL, causing the left front wheel 1FL to rotate. The gearbox 11FL is also fixed to a joint 9FL. The motor 10FL, gearbox 11FL, and left front wheel 1FL are integrated.

[0060] The kingpin 12FL is composed of a pin body 121FL, a bolt (pin head) 122FL, a bearing 123FL, and a nut 124FL.

[0061] The pin body 121FL passes through a small hole 91F (see FIGS. 5A to 5C) provided in the joint 9FL and is fixed by a bolt 122FL and a nut 124FL. The bearing 123FL is fixed to the front frame 201 (see FIGS. 3A to 3C) via a suspension arm 13FL.

[0062] With the above configuration, the integrated motor 10FL, gearbox 11FL, and left front wheel 1FL rotate and move in a horizontal plane relative to the front frame 201 around the kingpin 12FL in conjunction with the movement of the knuckle 8FL.

[0063] The upper end of the suspension 14FL is fixed to the front frame 201 via a suspension arm 13FL, and the lower end is connected to a joint 9FL. Connecting one end of the tie rod 7FL to the link 6FL via a rod end bearing 65FL gives the left front wheel 1FL more freedom of movement in the vertical direction, reducing restrictions on the steering mechanism.

[0064] The operation of this four-wheel traveling device is as follows. As shown in Figure 4A and other figures, mounts 5F, 5R are fixed to the floor plate 2 and are not linked to the extension and contraction of rod 32. Therefore, the positions of shafts 51FL, 51FR, 51RL, and 51RR provided on mounts 5F, 5R are fixed, and therefore the position of small hole 61 (see Figure 6A and other figures) in link 6 is also fixed.

[0065] Meanwhile, because bridge 4 moves in conjunction with the extension and contraction of rod 32, shaft 33 attached to rod 32 and shaft 41 attached to bridge 4 also move in conjunction with the extension and contraction of rod 32. This causes link 6 to move as well. More specifically, link 6 rotates in a horizontal plane around the position of small hole 61, which is fixed in position. As a result, tie rods 7 connected to links 6, and ultimately knuckles 8, move, controlling the direction of the wheels.

[0066] 3A, 4A, and 5A, when traveling straight, the rod 32 of the actuator 3 is controlled by the controller 102 to be at a predetermined reference position. At this time, when traveling straight, the shaft 33 is such that the front left wheel 1FL, front right wheel 1FR, rear left wheel 1RL, and rear right wheel 1RR are all parallel to the y direction.

[0067] 3B, 4B, and 5B, when turning right, the controller 102 controls the rod 32 of the actuator 3 so that it extends to the right from the reference position. In conjunction with the extension of the rod 32 to the right, the bridge 4, the link 6, the tie rod 7, and the knuckle 8 move.

[0068] Specifically, as the rod 32 extends to the right, the shaft 33 moves relative to the rear wheel side of the slit 63FL in the link 6FL for the left front wheel 1FL, causing the link 6FL to rotate counterclockwise around the position of the small hole 61FL (see Figure 6B). This causes the small hole 62FL, to which the tie rod 7FL is connected, to move leftward, which in turn causes the knuckle 8FL connected to the tie rod 7FL to also move leftward. This causes the left front wheel 1FL, gearbox 11FL, and motor 10FL to rotate clockwise together in a horizontal plane around the kingpin 12FL (small hole 91FL in the joint 9FL). As a result, the left front wheel 1FL faces rightward.

[0069] Furthermore, as the rod 32 extends to the right, the shaft 33 moves relative to the rear wheel side of the slit 63FR in the link 6FR for the right front wheel 1FR, causing the link 6FR to rotate counterclockwise around the position of the small hole 61FR. This causes the small hole 62FR, to which the tie rod 7FR is connected, to move leftward, which in turn causes the knuckle 8FR connected to the tie rod 7FR to move leftward. As a result, the right front wheel 1FR, gearbox 11FR, and motor 10FR rotate clockwise together in a horizontal plane around the kingpin 12FR (small hole 91FR in joint 9FR). As a result, the right front wheel 1FR faces rightward.

[0070] Furthermore, as the rod 32 extends to the right, the shaft 33 moves relative to the front wheel side of the slit 63RL in the link 6RL for the left rear wheel 1RL, causing the link 6RL to rotate clockwise around the position of the small hole 61RL. This causes the small hole 62RL, to which the tie rod 7RL is connected, to move leftward, which in turn causes the knuckle 8RL connected to the tie rod 7RL to move leftward as well. This causes the left rear wheel 1RL, gearbox 11RL, and motor 10RL to rotate counterclockwise in a horizontal plane together around the kingpin 12RL (small hole 91RL in the joint 9RL). As a result, the left rear wheel 1RL faces rightward.

[0071] Furthermore, as the rod 32 extends to the right, the shaft 33 moves relative to the front wheel side of the slit 63RR in the link 6RR for the right rear wheel 1RR, causing the link 6RR to rotate clockwise around the position of the small hole 61RR. This causes the small hole 62RR, to which the tie rod 7RR is connected, to move leftward, which in turn causes the knuckle 8RR connected to the tie rod 7RR to move leftward. As a result, the right rear wheel 1RR, gearbox 11RR, and motor 10RR rotate counterclockwise in a horizontal plane as a unit around the kingpin 12RR (small hole 91RR in the joint 9RR). As a result, the right rear wheel 1RR faces rightward.

[0072] In this way, in conjunction with the extension of rod 32 to the right, the left front wheel 1FL and the right front wheel 1FR rotate clockwise in the horizontal plane and face to the right, and the left rear wheel 1RL and the right rear wheel 1RR rotate counterclockwise in the horizontal plane and face to the left.

[0073] Next, a left turn will be described. As shown in Fig. 3C, when turning left, the controller 102 controls the rod 32 of the actuator 3 so that it contracts to the left from the reference position. In conjunction with the contraction of the rod 32 to the left, the bridge 4, link 6, tie rod 7, and knuckle 8 move.

[0074] Specifically, as the rod 32 retracts to the left, the shaft 33 moves relative to the slit 63FL of the link 6FL for the left front wheel 1FL toward the front wheel, causing the link 6FL to rotate clockwise around the position of the small hole 61FL (see FIG. 6C). This causes the small hole 62FL, to which the tie rod 7FL is connected, to move to the right, which in turn causes the knuckle 8FL connected to the tie rod 7FL to also move to the right. This causes the left front wheel 1FL, gearbox 11FL, and motor 10FL to rotate counterclockwise in a horizontal plane together around the kingpin 12FL (small hole 91FL of the joint 9FL). As a result, the left front wheel 1FL faces left.

[0075] Furthermore, as the rod 32 retracts to the left, the shaft 33 moves relative to the front wheel side of the slit 63FR in the link 6FR for the right front wheel 1FR, causing the link 6FR to rotate clockwise around the position of the small hole 61FR. This causes the small hole 62FR, to which the tie rod 7FR is connected, to move to the right, which in turn causes the knuckle 8FR, connected to the tie rod 7FR, to also move to the right. This causes the right front wheel 1FR, gearbox 11FR, and motor 10FR to rotate counterclockwise together in a horizontal plane around the kingpin 12FR (small hole 91FR in the joint 9FR). As a result, the right front wheel 1FR faces left.

[0076] Furthermore, as the rod 32 retracts to the left, the shaft 33 moves relative to the rear wheel side of the slit 63RL in the link 6RL for the left rear wheel 1RL, causing the link 6RL to rotate counterclockwise around the position of the small hole 61RL. This causes the small hole 62RL, to which the tie rod 7RL is connected, to move to the right, which in turn causes the knuckle 8RL connected to the tie rod 7RL to also move to the right. This causes the left rear wheel 1RL, gearbox 11RL, and motor 10RL to rotate clockwise together in a horizontal plane around the kingpin 12RL (small hole 91RL in the joint 9RL). As a result, the left rear wheel 1RL faces right.

[0077] Furthermore, as the rod 32 retracts to the left, the shaft 33 moves relative to the rear wheel side of the slit 63RR in the link 6RR for the right rear wheel 1RR, causing the link 6RR to rotate counterclockwise around the position of the small hole 61RR. This causes the small hole 62RR, to which the tie rod 7RR is connected, to move to the right, which in turn causes the knuckle 8RR connected to the tie rod 7RR to move to the right. As a result, the right rear wheel 1RR, gearbox 11RR, and motor 10RR rotate clockwise in a horizontal plane as a unit around the kingpin 12RR (small hole 91RR in the joint 9RR). As a result, the right rear wheel 1RR faces left.

[0078] In this way, in conjunction with the rod 32 contracting to the left, the left front wheel 1FL and the right front wheel 1FR rotate counterclockwise in the horizontal plane and face left, and the left rear wheel 1RL and the right rear wheel 1RR rotate clockwise in the horizontal plane and face right.

[0079] 8 is a diagram showing a schematic diagram of the relationship between the extension and contraction of the rod 32 and the traveling direction of the four-wheel traveling device. The horizontal axis represents the position of the rod 32, with "0" representing the reference position, a positive value representing an extension to the right from the reference position, and a negative value representing a contraction to the left from the reference position. The vertical axis represents the traveling direction, and for convenience, "0" represents going straight, a positive value representing a right turn angle, and a negative value representing a left turn angle.

[0080] As shown in the figure, the more the rod 32 extends to the right, the greater the bend to the right, and the more the rod 32 contracts to the left, the greater the bend to the left.

[0081] Here, the traveling direction does not need to be symmetrical with respect to the reference position. In particular, in the case of autonomous driving, the controller 102, not a person, controls the actuator 3, so asymmetry is not a problem. It is possible to make the traveling direction symmetrical with respect to the reference position by devising the shape of the link 6 (for example, the shape and position of the slit 63, and the positions of the small holes 61 and 62). However, by making the links 6 the same shape and making the links 6 symmetrical, it is possible to reduce manufacturing costs.

[0082] Based on the above description, a person skilled in the art may be able to conceive additional effects and various modifications of the present invention, but the aspects of the present invention are not limited to the individual embodiments described above. Various additions, modifications, and partial deletions are possible within the scope of the conceptual idea and spirit of the present invention, which is derived from the content defined in the claims and their equivalents. For example, what is described herein as a single element (including what is depicted as a single element in the drawings) may be realized by multiple elements, and conversely, what is described herein as multiple elements (including what is depicted as multiple elements in the drawings) may be realized by a single element.

[0083] Furthermore, not all of the features described in this specification are essential requirements. In particular, features described in this specification but not included in the claims can be considered optional additional features.

[0084] It should be noted that the applicant is merely aware of the inventions disclosed in the documents listed in the "Prior Art Documents" section of this specification, and the present invention does not necessarily aim to solve the problems of the disclosed inventions. The problem that the present invention aims to solve should be determined by taking into consideration the entire specification. For example, if this specification states that a specific configuration achieves a certain effect, it can also be said that the present invention solves a problem that is the reverse of that effect. However, it is not necessarily intended that such a specific configuration be an essential requirement. [Explanation of symbols]

[0085] 1 wheel 1FL left front wheel 1FR right front wheel 1RL Left rear wheel 1RR right rear wheel 2 floor plates 21 Linear guide 22 Actuator Mount 3 Actuators (electric linear actuators) 31 Main body part 32 Rod 33 Shaft 34 Connecting member 4 Bridge (Steering Link Bridge) 41 Shaft 5 Mount (Steering Link Mount) 51 Shaft 6 Link (Steering Link Plate) 61,62 small hole 63 Slit 64,65 bearings 7 tie rod 71 Bearings 8 Knuckles 81 Small hole 9 Joint 91 Small hole 10 Motor 11 Gearbox 12 Kingpin 121 pin body 122 volts 123 Bearing 124 Nut 13 Suspension arm 14. Suspension 100 cameras 101 Memory 102 Controller 103 Tablet devices 201 Front frame body 202 Central frame 203 Rear frame body

Claims

1. A four-wheel traveling device that performs steering by converting expansion and contraction motion of one linear actuator into rotational motion of a first front wheel, a second front wheel, a first rear wheel, and a second rear wheel in a horizontal plane via links, the first link for the first front wheel and the third link for the first rear wheel lie substantially in a first horizontal plane and rotate within the first horizontal plane; the second link for the second front wheel and the fourth link for the second rear wheel lie substantially in a second horizontal plane and rotate within the second horizontal plane; The four-wheel traveling device, wherein the first horizontal plane and the second horizontal plane are different.

2. A four-wheel driving device that performs steering by converting the extension and contraction motion of one linear actuator via a link into rotational motion in a horizontal plane of a first front wheel, a second front wheel, a first rear wheel, and a second rear wheel, The linear actuator has a rod that expands and contracts in a predetermined direction, the four-wheel traveling device includes a bridge that moves in the predetermined direction in conjunction with the rod, the first link for the first front wheel and the third link for the first rear wheel rotate in a horizontal plane in conjunction with the extension and contraction of the linear actuator by a first shaft provided on the rod; a second link for the second front wheel and a fourth link for the second rear wheel rotate within a horizontal plane in conjunction with the extension and contraction of the linear actuator via a second shaft provided on the bridge;

3. a slit is provided in each of the first link and the third link, 3. The four-wheel traveling device according to claim 2, wherein the first shaft is slidably fitted in the slits of the first link and the third link.

4. a slit is provided in each of the second link and the fourth link, 4. The four-wheel traveling device according to claim 2 or 3, wherein the second shaft is slidably fitted in the slits of the second link and the fourth link.

5. 5. The four-wheel traveling device according to claim 3, wherein the slit extends parallel to a line connecting the first front wheel and the first rear wheel when traveling straight.

6. A four-wheel driving device as described in any one of claims 1 to 5, wherein the linear actuator expands and contracts parallel to a line connecting the first front wheel and the second front wheel.

7. A four-wheel driving device as described in any one of claims 1 to 6, wherein at least two of the first link, the second link, the third link, and the fourth link have the same shape.

8. A four-wheel driving device as described in claim 7, wherein the first link, the second link, the third link, and the fourth link all have the same shape.

9. Each of the first to fourth links is provided with a small hole into which a third shaft that does not interlock with the rod is fitted, 6. The four-wheel traveling device according to claim 2, wherein each of the first to fourth links rotates in a horizontal plane around the small hole.

10. the linear actuator is disposed closer to the first front wheel and the first rear wheel than a line connecting the centers of the first front wheel and the second front wheel and the center of the first rear wheel and the second rear wheel; When the rod of the linear actuator is in the reference position, the four-wheel traveling device moves straight, When the rod of the linear actuator extends from the reference position, the four-wheel traveling device bends toward the second front wheel and the second rear wheel, 10. The four-wheel traveling device according to claim 1, wherein when the rod of the linear actuator is retracted from a reference position, the four-wheel traveling device bends toward the first front wheel and the first rear wheel.

11. A camera and 11. The four-wheel traveling device according to claim 1, further comprising: a controller that automatically controls the extension and contraction of the linear actuator based on the image of the camera.

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