JP2023144780A - Six-wheel type electric vehicle - Google Patents

Abstract

To provide a six-wheel type electric vehicle having high travel performance.SOLUTION: A six-wheel type electric vehicle includes: a pair of right and left front wheels; intermediate wheels disposed behind the front wheels and working as a pair of right and left driving wheels; a pair of right and left rear wheels disposed behind the intermediate wheels; and a connection part connecting each of right and left of the front wheels, the intermediate wheels and the rear wheels. The connection part includes: a first link linking and suspending the front wheel and the intermediate wheel; a second link to which the rear wheel is linked; and a third link turnably linked to the first link via a first joint part and turnably linked to the second link via a second joint part. The first joint part is located under a line segment connecting the rotation center of the front wheel and the rotation center of the intermediate wheel.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a six-wheel electric vehicle.

A six-wheeled electric vehicle has a total of six wheels, consisting of a pair of middle wheels that are driving wheels, and four driven wheels arranged two before and two behind the middle wheels. A six-wheel electric vehicle can have a smaller turning radius than a four-wheel electric vehicle, so it can turn in a smaller radius when traveling. Further, the six-wheeled electric vehicle has high running stability because it can further suppress the turning of the vehicle body due to its own weight when tilting.

On the other hand, in a six-wheeled electric vehicle, if the middle wheel moves away from the ground due to an uneven surface, a step, or a connection between a flat surface and a slope, the driving force of the middle wheel is transferred to the ground. can no longer be transmitted. Therefore, it is difficult for six-wheeled electric vehicles to stably overcome bumps in the road surface. An example of a six-wheel electric wheelchair developed to solve this problem is disclosed in Patent Document 1.

The six-wheel electric vehicle disclosed in Patent Document 1 has a front wheel, a middle wheel, and a rear wheel each mounted on a suspension as a pair. The suspension includes a bogie link section that suspends the front wheel and the middle wheel in a connected state, a rocker link section that suspends the rear wheel, and a joint section that rotatably connects the bogie link section and the rocker link section. It is composed of a rocker bogie link mechanism with When the direction connecting the front wheel and the rear wheel is defined as the front-rear direction, the direction perpendicular to the front-rear direction and parallel to the horizontal direction is the left-right direction, and the direction orthogonal to the front-rear direction and the left-right direction is the height direction, the rocker link section has a frame member that extends linearly toward the rear end with the front end connected to the joint. The frame member is arranged in an inclined position with a rearward height that gradually increases from the front end side to the rear end side with reference to the height from the ground based on the flat surface. The rear wheel is suspended independently on both left and right sides by at least one fulcrum shaft disposed at a rear wheel support portion on the rear end side of the frame member at a position higher than the axis of the middle wheel. .

Japanese Patent Application Publication No. 2020-151160

However, in the six-wheeled electric vehicle described in Patent Document 1, due to the structure of the bogie link and the front wheels and rear wheels suspended on the bogie link, the bogie link and rocker link are derived from the propulsive force from the drive wheels. The moment around the joints that connect the front wheels acts in the direction of raising the front wheels upwards, which may cause the front wheels to rise unintentionally, impairing running performance.

An object of the present disclosure is to provide a six-wheel electric vehicle with high running performance.

The six-wheeled electric vehicle of the present disclosure includes a pair of left and right front wheels, a pair of left and right drive wheels arranged behind the front wheels, and a pair of left and right rear wheels arranged behind the middle wheels. a connecting portion that connects the front wheel, the middle wheel, and the rear wheel on each side, the connecting portion connecting and suspending the front wheel and the middle wheel; a second link to which a rear wheel is connected; and a second link rotatably connected to the first link via a first joint, and rotatably connected to the second link via a second joint. the first joint portion is located below a line segment connecting the center of rotation of the front wheel and the center of rotation of the middle wheel.

According to the six-wheel electric vehicle of the present disclosure, it is possible to provide a six-wheel electric vehicle with high running performance.

Left side view of the six-wheeled electric vehicle in the first embodiment Front view of the six-wheeled electric vehicle in the first embodiment Rear view of the six-wheeled electric vehicle in the first embodiment A conceptual diagram of a conventional six-wheeled electric vehicle seen from the side to which the configuration of the first embodiment is not applied. Conceptual diagram of the six-wheeled electric vehicle in the first embodiment viewed from the side Left side view of the six-wheeled electric vehicle in the second embodiment A plan view of a six-wheeled electric vehicle in the second embodiment A plan view of an omniwheel used as a driven wheel of a six-wheeled electric vehicle in a second embodiment Conceptual diagram of a six-wheeled electric vehicle in the second embodiment viewed from above Left side view of the six-wheeled electric vehicle in the third embodiment Conceptual diagram of a six-wheeled electric vehicle in the third embodiment viewed from above Flowchart showing the operation of changing the toe angle according to the external environment in the six-wheeled electric vehicle in the third embodiment

[First embodiment]
First, a first embodiment of the present disclosure will be described with reference to the drawings. However, the present disclosure is not limited to the following first embodiment and second embodiment. Further, in order to clarify the explanation, the following description and drawings are appropriately simplified. FIG. 1 is a left side view of a six-wheel electric vehicle. FIG. 2 is a front view of the six-wheel electric vehicle. FIG. 3 is a rear view of the six-wheel electric vehicle. FIG. 4 is a conceptual diagram of a conventional six-wheeled electric vehicle to which the configuration of the first embodiment, as typified by Patent Document 1, is not applied, viewed from the side. FIG. 5 is a conceptual diagram of a six-wheel electric vehicle viewed from the side.

A six-wheel electric vehicle 1 shown in FIGS. 1 to 3 is an electric vehicle having six wheels. The six-wheeled electric vehicle 1 can be used, for example, as a mobile robot that transports goods outdoors, indoors, in facilities, or on private land, or as a vehicle for people to move around outdoors, indoors, in facilities, or on private land. An example of this is the traveling section of an electric wheelchair. The six-wheel electric vehicle 1 includes a vehicle body portion 2, a main body portion 3, and a control portion 4.

The vehicle body portion 2 includes a front wheel 11, a middle wheel 12, a rear wheel 13, a motor 14, and a connecting portion 20, and has a function related to movement of the six-wheel electric vehicle 1.

The main body part 3 has functions such as loading in the six-wheeled electric vehicle 1. Examples of the main body part 3 include a locker-like structure for transporting articles, a chair for boarding a person, and the like. Note that the main body portion 3 is not limited to a locker-like structure or a chair, and may have other structures. Further, in the six-wheeled electric vehicle 1, the main body portion 3 does not need to have a function such as loading.

The control unit 4 includes a battery, a control device such as a motor driver or a speed determination unit, a storage unit, and the like. Although the control section 4 is arranged inside the vehicle body section 2 and below the main body section 3, the arrangement location of the control section 4 is not limited to the above-mentioned position.

Next, the detailed configuration of the vehicle body portion 2 will be explained. The vehicle body part 2 includes a pair of front wheels 11 (left front wheel 11L, right front wheel 11R), middle wheels 12 (left middle wheel 12L, right middle wheel 12R), rear wheels 13 (left rear wheel 13L, A right rear wheel 13R) and a motor 14 (a left motor 14L and a right motor 14R) are provided. The direction in which the front wheel 11, middle wheel 12, and rear wheel 13 are connected is the front-rear direction. Further, the direction in which the pair of front wheels 11L, 11R are connected together, the direction in which the pair of middle wheels 12L, 12R are connected together, and the direction in which the pair of rear wheels 13L, 13R are connected are in the left-right direction.

The middle wheel 12 is a driving wheel, and is rotated by the drive of the motor 14 . The left middle wheel 12L is connected to the left motor 14L, and the right middle wheel 12R is connected to the right motor 14R. The left motor 14L and the right motor 14R are independently controlled by the control unit 4, and rotate the left middle wheel 12L and the right middle wheel 12R independently of each other. The diameter of the middle wheel 12 is larger than the diameter of the front wheel 11 and the rear wheel 13, or equal to the diameter of the front wheel 11 and the rear wheel 13.

The front wheels 11 and the rear wheels 13 are driven wheels, and rotate according to the movement of the six-wheel electric vehicle 1. That is, when the middle wheel 12 is driven and the six-wheel electric vehicle 1 moves, the front wheels 11 and the rear wheels 13 rotate following the movement of the six-wheel electric vehicle 1. The front wheels 11 and the rear wheels 13 are wheels that can move freely in all directions, that is, in the front, back, left, and right directions. As the front wheel 11 and the rear wheel 13, omni wheels or casters can be exemplified.

The connecting portion 20 includes a pair of left and right first links 21, a pair of left and right second links 22, a pair of left and right third links 23, and a fourth link 24.

The first link 21 on the left side connects and suspends the front wheel 11L on the left side and the middle wheel 12L, and the first link 21 on the right side connects and suspends the front wheel 11R on the right side and the middle wheel 12R. Each first link 21 is connected to each front wheel 11L, 11R via a first link front wheel connection portion 25, and to each middle wheel 12L, 12R via a first link middle wheel connection portion 26.

The left second link 22 is connected to the left rear wheel 13L, and the right second link 22 is connected to the right rear wheel 13L. Each second link 22 is connected to each rear wheel 13L, 13R via a second link rear wheel connecting portion 27.

The third link 23 on the left side is rotatably connected to the first link 21 on the left side via a first joint section 28 on the left side, and is connected to the second link 22 on the left side via a second joint section 29 on the left side. are rotatably connected. The third link 23 on the right side is rotatably connected to the first link 21 on the right side via a first joint section 28 on the right side, and is connected to the second link 22 on the right side via a second joint section 29 on the right side. are rotatably connected. The left and right third links 23 are connected by a fourth link 24 extending in the left-right direction. The fourth link 24 may be integrated with the left and right third links 23 or may be integrated with the main body portion 3. It is desirable that a stopper 30 is installed on each of the left and right third links 23, and it is desirable that the operating range of the swinging motion (rotation) of the left and right first links 21 is limited by the stopper 30.

In the conventional example, as shown in FIG. 4, the first joint 28 connecting the first link 21 and the third link 23 is a line segment connecting the rotation center 11C of the front wheel 11 and the rotation center 12C of the middle wheel 12. It is configured to be located above the At this time, as described in the problem with the conventional example, the moment around the joint that connects the bogie link and rocker link, which is derived from the propulsive force of the drive wheels, acts in the direction of raising the front wheel upwards, causing the front wheel to unintentionally move upward. may increase and impair running performance. Furthermore, when climbing over a step in front, there is a component that is lost when the reaction force T received by the front wheel 11 from the step is converted into torque τ that causes the first link 21 to swing around the first joint portion 28. .

On the other hand, in the six-wheeled electric vehicle 1 of the first embodiment, as shown in FIG. It is configured to be located below a line segment connecting the rotation center 12C of the middle ring 12. By arranging the first joint portion 28 below the line segment connecting the rotation center 11C of the front wheel 11 and the rotation center 12C of the middle wheel 12, the drive generated by the middle wheel 12 is generated by the torque generated from the motor 14. The torque τ around the first joint portion 28 derived from the force F can prevent the first link 21 from unexpectedly swinging and causing the front wheel 11 to rise. Furthermore, when climbing over a step in front, the reaction force T that the front wheel 11 receives from the step acts in a direction that generates a torque τ that causes the first link 21 to swing around the first joint portion 28, which improves the ability to get over the step. can be improved. Therefore, it is possible to provide a six-wheeled electric vehicle 1 with high running performance.

If AH is the distance between the first joint 28 and the line segment FM connecting the rotation center 11C of the front wheel 11 and the rotation center 12C of the middle wheel 12, then the distance AH is 1/7 or more of the radius of the middle wheel 12. It is desirable that the length be 2/2 or less. For example, when the diameter of the middle wheel 12 is 280 mm, that is, the radius is 140 mm, the first joint portion 28 is located at a position 25 mm downward from a line connecting the rotation center 11C of the front wheel 11 and the rotation center 12C of the middle wheel 12. Deploy. The larger the distance AH, the more it is possible to prevent the front wheel 11 from lifting up unexpectedly and improve the performance of getting over a step. It works in the direction of floating the middle ring 12 upward. For this reason, if the distance AH is excessively large, there is a risk that sufficient frictional force between the middle wheel 12 and the ground will not be obtained, the middle wheel 12 will slip, and a sufficient driving force F will not be obtained.

Next, the arrangement relationship among the front wheel 11, the middle wheel 12, the rear wheel 13, the first joint 28, and the second joint 29 will be explained. Each distance FM_HORIZ, FM, MR_HORIZ, MR, FA, AM, and BR is defined as follows.
Distance FM_HORIZ: Horizontal distance between the front wheels 11 and middle wheels 12 when the six-wheeled electric vehicle 1 stands upright on a plane (horizontal distance from the rotation center 11C of the front wheels 11 to the rotation center 12C of the middle wheels 12)
Distance FM: Distance between the front wheels 11 and middle wheels 12 when the six-wheel electric vehicle 1 is standing upright on a flat surface (distance from the rotation center 11C of the front wheels 11 to the rotation center 12C of the middle wheels 12)
Distance MR_HORIZ: Horizontal distance between the middle wheel 12 and the rear wheel 13 when the vehicle is upright on a flat surface (horizontal distance from the center of rotation 12C of the middle wheel 12 to the center of rotation 13C of the rear wheel 13)
Distance MR: Distance between the middle wheel 12 and the rear wheel 13 when the six-wheel electric vehicle 1 is standing upright on a flat surface (distance from the center of rotation 12C of the middle wheel 12 to the center of rotation 13C of the rear wheel 13)
Distance FA: Distance between the front wheels 11 and the first joint 28 when the six-wheel electric vehicle 1 is standing upright on a plane (distance in the line segment FM direction from the rotation center 11C of the front wheel 11 to the first joint 28)
Distance AM: distance between the first joint 28 and the middle wheel 12 when the six-wheeled electric vehicle 1 is standing upright on a plane (distance in the line segment FM direction from the first joint 28 to the center of rotation 12C of the middle wheel 12)
Distance BR: distance between the second joint 29 and the rear wheel 13 when the six-wheeled electric vehicle 1 is standing upright on a plane (distance in the direction of the line segment MR from the second joint 29 to the rotation center 13C of the rear wheel 13)

The ratio of distance FM_HORIZ to distance MR_HORIZ, FM_HORIZ:MR_HORIZ, is set to 1:1. The ratio of the distance FM_HORIZ to the distance MR_HORIZ is not limited to 1:1 and can be changed as appropriate, but it is desirable that it be close to 1:1. Furthermore, FA:AM, which is the ratio of distance FA to distance AM, is set to 2:1. The ratio of distance FA to distance AM is not limited to 2:1 and can be changed as appropriate, but it is ideal that FA/AM is set to a value greater than 1 and less than or equal to 2. It is true. By making FA/AM larger than 1, the proportion of the own weight acting on the middle wheel 12 increases, the frictional force of the middle wheel 12 can be increased, and the running can be stabilized against irregularities on the ground.

It is desirable that a suspension 31 be connected between the second link 22 and the third link 23 on the left and right sides. Each suspension 31 is connected to each second link 22 via a second suspension connection part 32 and to each third link 23 via a third suspension connection part 33. The suspension 31 plays the role of limiting the rocking of the rear wheel 13 and making the rear wheel 13 adapt to the unevenness of the ground. It is desirable that the second suspension connection part 32 and the third suspension connection part 33, which are the connection parts of the suspension 31, be provided with a swing shaft. It may be fixed to three links 23. The suspension spring 34 constituting the suspension 31 is desirably set so that the neutral position is a state in which the vehicle body 2 is horizontal due to its own weight.

The stroke of the suspension 31 is preferably set as follows using the characteristics of the suspension spring 34, a stopper, etc. The stroke of the suspension 31 is such that when it is in the most compressed state, that is, when the rear wheel 13 is located at the highest end, the second link 22 is horizontal to the horizontal plane, or the rear wheel 13 is in the most compressed state. It is desirable to set the position so that it is located at the bottom. The stroke of the suspension 31 is set to a height at which the rear wheel 13 lowers from the neutral position by more than the height of the step to overcome when it is in its most extended state, that is, when the rear wheel 13 is located at the lowest end. is desirable. With such a setting, the six-wheeled electric vehicle 1 can easily travel flexibly over bumps.

[Second embodiment]
Next, a second embodiment of the present disclosure will be described with reference to the drawings. FIG. 6 is a left side view of the six-wheel electric vehicle. FIG. 7 is a plan view of the six-wheel electric vehicle. FIG. 8 is a plan view of an omniwheel used as a driven wheel of a six-wheel electric vehicle. FIG. 9 is a conceptual diagram of a six-wheel electric vehicle viewed from above. Note that the same components as those of the six-wheeled electric vehicle 1 of the first embodiment will be given the same reference numerals and names, and a description thereof may be omitted. Further, structures that have the same functions as the six-wheeled electric vehicle 1 of the first embodiment but differ in arrangement, shape, etc. may be given the same name to simplify the explanation.

A six-wheel electric vehicle 100 according to the second embodiment shown in FIGS. 6 and 7 is a vehicle in which each front wheel 111 and each rear wheel 113 are formed of omni wheels. The six-wheeled electric vehicle 100 has a configuration that can improve the performance of getting over side steps due to the arrangement of the wheels. The six-wheel electric vehicle 100 of the second embodiment differs from the six-wheel electric vehicle 1 of the first embodiment in the arrangement and angle of the front wheels 111 and rear wheels 113, and the surrounding structure is different from the six-wheel electric vehicle 100 of the first embodiment. This is different from the type electric vehicle 1.

The six-wheel electric vehicle 100 includes a vehicle body portion 110, a main body portion 3, and a control portion 4. The vehicle body portion 110 includes a pair of front wheels 111 (left front wheel 111L, right front wheel 111R), middle wheels 12 (left middle wheel 12L, right middle wheel 12R), and rear wheels 113 (left rear wheel 113L, A right rear wheel 113R) and a motor 14 (a left motor 14L and a right motor 14R) are provided. The vehicle body section 110 further includes a connecting section 120. The connecting portion 120 includes a pair of left and right first links 121, a pair of left and right second links 122, a pair of left and right third links 123, and a fourth link 124. Similar to the six-wheel electric vehicle 1 of the first embodiment, the first joint portion 28 of the six-wheel electric vehicle 100 is located below the first link front wheel connecting portion 25 and the first link middle wheel connecting portion 26. There is. Furthermore, regarding the arrangement relationship of the front wheel 111, middle wheel 12, rear wheel 113, first joint portion 28, and second joint portion 29 of the six-wheeled electric vehicle 100, each distance is defined similarly to the first embodiment. FM_HORIZ, FM, MR_HORIZ, MR, FA, AM, and BR are set to satisfy the same relationship as in the first embodiment.

The front wheel 111 and the rear wheel 113 are constituted by an omni wheel 115 shown in FIG. The omniwheel 115 is an omnidirectional wheel including a plurality of rollers 116, and the rollers 116, each of which rotates around the circumference, are lined up on the outer circumference of the wheel 117, so that the rotation direction of the wheel 117 and the wheel axis 118 are aligned. A wheel that allows movement in the direction along the Note that there are omnidirectional wheels called omni-wheels other than the structure shown in FIG. 8, and the omni-wheel used in the present disclosure is not limited to the structure shown in FIG. 8.

The omni-wheel 115 overcomes steps in the outer circumferential direction using the outer periphery of the omni-wheel 115 in the same way as normal wheels, while the omni-wheel 115 overcomes steps on the side of the wheel by rollers disposed on the outer periphery. 116 to get over the step. The roller 116 arranged on the outer circumference is smaller than the outer diameter of the omniwheel 115. In general, the larger the wheel diameter, the larger the level difference that can be overcome. In a vehicle in which the front wheels 111 are composed of omni wheels 115, if the toe angle when each front wheel 111 is arranged in a toe-out state is a positive angle, the toe angle of each front wheel 111 is 0° or less or 0°. If it is close to , the performance for climbing over the level difference existing on the side of the vehicle will be low. Note that the state in which the front wheels 111 are toe-out means that the front wheels 111 are rotated so that the front ends of the front wheels 111 open outward of the six-wheeled electric vehicle 100, that is, the distance between the front ends is larger than the distance between the rear ends. 111 is arranged with an inclination.

As shown in FIGS. 7 and 9, each front wheel 111 of the six-wheel electric vehicle 100 is tilted so that the front end opens outward from the six-wheel electric vehicle 100 with respect to the forward traveling direction. will be placed. In this way, by arranging each front wheel 111 so that it is toe-out, it is possible to overcome a step not only on the outer circumference of the roller 116 but also on the outer circumference of the wheel 117, so that the toe angle θ1 shown in FIG. 9 can be reduced to 0°. The performance of climbing over side steps is improved compared to the case where the Ideally, the toe angle θ1 of each front wheel 111 is 5° or more and 45° or less. The larger the toe angle θ1 is, the better the performance for getting over the side steps is, but the lower the performance for getting over the front steps. Therefore, it is desirable to set the toe angle θ1 according to the driving environment and desired performance.

As a method of arranging each front wheel 111 so that it is toe-out, as shown in FIG. 7, a bent first link 121 may be used, or a fastening structure for making it toe-out may be provided. . As shown in FIG. 7, the method of forming the first link 121 in a bent structure can reduce the number of parts and provide the simplest structure. In this case, the shapes of the first link front wheel connecting portion 25, the third link 123, the fourth link 124, and the first joint portion 128 are set in consideration of the shape of the first link 121 and the range of movement during rocking. .

Each front wheel 111 is arranged so as to be toe-out, and is also arranged further inside the vehicle body than each middle wheel 12 . By arranging each front wheel 111 on the inner side of the vehicle body than each middle wheel 12, when the six-wheeled electric vehicle 100 turns, each front wheel 111 contacts a step on the side and tilts with respect to the step. Therefore, the outer periphery of the omni wheel 115 and the outer periphery of the roller 116 are both lateral, similar to the case where each front wheel 111 is arranged so as to be toe-out without deteriorating its performance against a bump in front. can overcome the steps.

When arranging each front wheel 111 to the inside of each middle wheel 12, the position of each front wheel 111 is determined between a contact point P1 of the front wheel 111 with the ground and a contact point P2 of the middle wheel 12 with the ground, as shown in FIG. It is set based on the angle Φ formed between a line connecting L1 and a line L2 parallel to the longitudinal direction of the vehicle body. In other words, the more the front wheels 111 are arranged inside, the larger the angle Φ becomes. The larger the angle Φ, the better the performance of getting over side steps, but the smaller the volume in which equipment can be mounted inside the vehicle body. Considering this, it is desirable that the sum of the angle Φ and the toe angle θ1 (θ1+Φ) is 10° or more and 60° or less.

The inclination and arrangement of each front wheel 111 are similarly applied to each rear wheel 113. Each rear wheel 113 is arranged in a toe-in state. Note that the toe-in state of each rear wheel 113 means that the rear end of each rear wheel 113 is opened to the outside of the six-wheel electric vehicle 100, that is, the interval between the front ends is smaller than the interval between the rear ends. , each rear wheel 113 is arranged with an inclination. It is desirable that the toe angle θ1 of each front wheel 111 and the toe angle θ2 of each rear wheel 113 be the same angle or approximately the same angle. In the second embodiment, as a method of arranging each rear wheel 113 so as to provide toe-in, a configuration using a bent second link 122 is applied, but a fastening structure for providing toe-in may also be provided. good.

[Third embodiment]
Next, a third embodiment of the present disclosure will be described with reference to the drawings. FIG. 10 is a left side view of the six-wheel electric vehicle. FIG. 11 is a conceptual diagram of a six-wheeled electric vehicle viewed from above. FIG. 12 is a flowchart showing the operation of changing the toe angle according to the external environment in a six-wheeled electric vehicle. Note that the same components as those of the six-wheeled electric vehicle 100 of the second embodiment will be given the same reference numerals and names, and a description thereof may be omitted. Furthermore, structures that have the same structure and function as the six-wheeled electric vehicle 100 of the second embodiment but differ in arrangement, shape, etc. may be given the same name and the description may be simplified.

The six-wheel electric vehicle 200 shown in FIG. 10 has a structure in which the toe angle θ1 of each front wheel 111 and the toe angle θ2 of each rear wheel 113 can be changed according to the external environment.

The six-wheel electric vehicle 200 includes a vehicle body section 210, a main body section 3, and a control section 4. The vehicle body portion 210 includes a pair of front wheels 111, a middle wheel 12, a rear wheel 113, and a motor 14, respectively.

The vehicle body section 210 further includes four toe angle drive sections 211. The toe angle drive unit 211 includes a motor having a rotating shaft extending in the vertical direction, a speed reducer, an encoder that recognizes the toe angle, and peripheral mechanisms thereof. The two toe angle drive units 211 support each front wheel 111 via a bracket 212 fixed to the rotating shaft of the motor and a front wheel coupling unit 213. The remaining two toe angle drive units 211 support each rear wheel 113 via a bracket 214 fixed to the rotating shaft of the motor and a rear wheel coupling unit 215. With this configuration, when the motor of the toe angle drive unit 211 is driven, the toe angle θ1 of the front wheel 111 or the toe angle θ2 of the rear wheel 113 is changed, as shown in FIG. The toe angle drive unit 211 is desirably configured to be able to change the toe angle θ1 of the front wheels 111 or the toe angle θ2 of the rear wheels 113 within a range of 0° or more and 45° or less. Note that the structure of the toe angle driving section 211 is not limited to the above-mentioned structure as long as the toe angles θ1 and θ2 can be changed.

The vehicle body part 210 further includes a connecting part 220. The connecting portion 220 includes a pair of left and right first links 221, a pair of left and right second links 222, a pair of left and right third links 223, and a fourth link 124. Each front wheel 111 is connected to a first link 221 via an attachment part of a toe angle drive part 211. Each rear wheel 113 is connected to a second link 222 via an attachment part of the toe angle drive part 211.

Similar to the six-wheel electric vehicle 100 of the second embodiment, the first joint portion 28 of the six-wheel electric vehicle 200 is connected to the rotation center 111C of the front wheel 111 via the toe angle drive portion 211 and the rotation center 12C of the middle wheel 12. It is placed below the line segment that connects the Further, regarding the arrangement relationship of the front wheel 111, middle wheel 12, rear wheel 113, first joint portion 28, and second joint portion 29 of the six-wheeled electric vehicle 200, each distance is defined similarly to the second embodiment. FM_HORIZ, FM, MR_HORIZ, MR, FA, AM, and BR are set to satisfy the same relationship as in the first embodiment. Note that a portion corresponding to the second link rear wheel connection portion 27 in the third embodiment is a connection portion 227 between the second link 222 and the rear wheel 113 via the toe angle drive portion 211.

If the six-wheeled electric vehicle 200 is a vehicle operated by a person, such as an electric wheelchair, the toe angles of the front wheels 111 and rear wheels 113 are adjusted by the person operating the operating unit according to the surrounding environment and the target traveling direction. You just need to configure it so that it can be done. When a person climbs over steps in the front and rear, the user operates the operation unit so that the toe angles θ1 and θ2 approach 0°, and when climbing over steps on the side, the toe angles θ1 and θ2 become larger (0°). Operate the operating section so that the value becomes a positive value exceeding 1.

On the other hand, if the six-wheeled electric vehicle 200 is an autonomously moving vehicle such as a robot, it is desirable to be able to automatically determine and change the toe angles of the front wheels 111 and rear wheels 113 depending on the external environment. The configuration at this time will be explained.

Step detection sections 231 for detecting external step conditions are arranged, for example, on the front surface and both left and right side surfaces of the main body 3. The step detection unit 231 is configured with a sensor that detects the contour shape of an object, such as LiDAR or a camera. Further, the control unit 4 is equipped with a step determination unit 232, a route determination unit 233, and a wheel angle setting unit 234 in addition to the components of the control unit 4 in the second embodiment. The step determination unit 232, route determination unit 233, and wheel angle setting unit 234 are all processors that execute programs stored in memory.

The operation of changing the toe angle according to the external environment will be explained with reference to the flowchart of FIG. 12. The level difference detection unit 231 images the contour shape around the six-wheeled electric vehicle 200 while the six-wheeled electric vehicle 200 is stopped, and detects the situation of the level difference (step S1). Next, the level difference determination unit 232 determines the presence or absence of a level difference around the six-wheel electric vehicle 200, and the height and position of the level difference, based on the detection result of the level difference detection unit 231 (step S2). The route determining unit 233 determines the traveling route of the six-wheel electric vehicle 200 based on the information set and input to the six-wheel electric vehicle 200 (step S3).

Next, if there is a step in the direction of travel determined by the route determining section 233, the wheel angle setting section 234 determines the toe angles θ1, θ2 of each wheel 111, 113 (the toe angles θ1, θ2 of each front wheel 111) according to the position of the step. The toe angle θ1 and the toe angle θ2 of each rear wheel 113 are set (step S4).

In the process of step S4, when the traveling direction is the left-right direction of the vehicle body, when the six-wheel electric vehicle 200 is turning, and when there is a step in the traveling direction, the wheel angle setting unit 234 sets the wheel angle setting unit 234 as shown in FIG. Toe angles θ1 and θ2 of the wheels 111 and 113 are set so that each front wheel 111 is in a toe-out state and each rear wheel 113 is in a toe-in state. In other cases, the wheel angle setting unit 234 sets the toe angles θ1 and θ2 of the respective wheels 111 and 113 to values close to 0°.

Further, when the traveling direction is forward and a step exists in front, or when the traveling direction is backward and a step exists in the rear, the wheel angle setting unit 234 sets the toe angle θ1, θ2 of each wheel 111, 113. Set to 0°. Further, when a step exists on the side and the six-wheeled electric vehicle 200 attempts to transfer over the step by turning, the wheel angle setting unit 234 sets the toe angles θ1 and θ2 of the wheels 111 and 113 to 45°, respectively. settings so that each front wheel 111 is toe-out and each rear wheel 113 is toe-in. Further, when a step exists diagonally ahead in the direction of travel, the wheel angle setting unit 234 sets the toe angles θ1, θ2 of each wheel 111, 113 between 0° and 45° depending on the height and position of the step. It is recommended to set it to a value.

Then, each toe angle driving section 211 changes the toe angle θ1 of the front wheel 111 and the toe angle θ2 of the rear wheel 113 based on the determination result in the wheel angle setting section 234 (step S5). Finally, the motor driver of the control unit 4 controls each motor 14 to cause the six-wheel electric vehicle 200 to travel (step S6). While the six-wheeled electric vehicle 200 is traveling, the processes of steps S1 to S5 are repeated, so that the six-wheeled electric vehicle 200 moves to the destination.

Note that the present disclosure is not limited to the above embodiments, and can be modified as appropriate without departing from the spirit.

The present disclosure has the effect of improving driving performance and can be applied to six-wheel electric vehicles such as electric wheelchairs and mobile robots.

1,100,200 Six-wheel electric vehicle 2,110,210 Body part 3 Main body part 4 Control part 11, 11L, 11R, 111, 111L, 111R Front wheel 11C, 111C Center of rotation of front wheel 12, 12L, 12R Middle wheel 12C Medium Center of rotation of wheels 13, 13L, 13R, 113, 113L, 113R Rear wheel 13C Center of rotation of rear wheels 14, 14L, 14R Motor 20, 120, 220 Connection part 21, 121, 221 First link 22, 122, 222 Second link 23,123,223 Third link 24,124 Fourth link 25 First link front wheel connecting portion 26 First link middle wheel connecting portion 27 Second link rear wheel connecting portion 28,128 First joint 29 Second joint Part 30 Stopper 31 Suspension 32 Second suspension connection part 33 Third suspension connection part 115 Omni wheel 116 Roller 117 Wheel 118 Wheel axle 211 Toe angle drive part 212, 214 Bracket 213 Front wheel connection part 215 Rear wheel connection part 227 Connection part 231 Step Detection unit 232 Level difference determination unit 233 Route determination unit 234 Wheel angle setting unit

Claims (14)

A pair of left and right front wheels,
a middle wheel that is a pair of left and right drive wheels arranged behind the front wheel;
a pair of left and right rear wheels arranged behind the middle wheel;
A connecting portion connecting the front wheel, the middle wheel, and the rear wheel on each of the left and right sides,
The connection part is
a first link that connects and suspends the front wheel and the middle wheel;
a second link to which the rear wheel is connected;
a third link rotatably connected to the first link via a first joint, and rotatably connected to the second link via a second joint,
The first joint portion is located below a line segment connecting the rotation center of the front wheel and the rotation center of the middle wheel.
Six-wheeled electric vehicle. The first joint portion is configured such that a distance to a line connecting the center of rotation of the front wheel and the center of rotation of the middle wheel is 1/7 or more and 1/2 or less of the radius of the middle wheel. is placed,
The six-wheel electric vehicle according to claim 1. The distance from the center of rotation of the front wheel to the first joint is longer than the distance from the center of rotation of the middle wheel to the first joint.
The six-wheel electric vehicle according to claim 1 or claim 2. The distance from the center of rotation of the front wheel to the first joint is more than one time and not more than twice the distance from the center of rotation of the middle wheel to the first joint.
The six-wheel electric vehicle according to claim 3. The pair of left and right front wheels are composed of omni wheels, and are arranged such that the distance between the front ends of the front wheels is different from the distance between the rear ends.
The six-wheel electric vehicle according to any one of claims 1 to 4. the pair of left and right front wheels are arranged in a toe-out state;
The six-wheel electric vehicle according to claim 5. The pair of left and right front wheels are arranged such that the toe angle is 5° or more and 45° or less,
The six-wheel electric vehicle according to claim 6. The pair of left and right front wheels are
The sum of the angle formed by a line connecting the contact point between the left front wheel and the ground and the left middle wheel and the ground with respect to the traveling direction and the toe angle of the front wheel is 10° or more and 60° or less,
Arranged so that the sum of the angle formed by the line connecting the right front wheel and the ground and the right middle wheel and the ground with respect to the traveling direction and the toe angle of the front wheel is 10° or more and 60° or less. has been,
The six-wheel electric vehicle according to claim 6 or 7. The pair of left and right front wheels are arranged inside the six-wheeled electric vehicle than the pair of left and right middle wheels,
The six-wheel electric vehicle according to any one of claims 5 to 8. The pair of left and right rear wheels are configured by omni wheels, and are arranged such that the distance between the front ends of the front wheels is different from the distance between the rear ends.
The six-wheel electric vehicle according to any one of claims 1 to 9. The pair of left and right rear wheels are arranged in a toe-in state,
The six-wheel electric vehicle according to claim 10. The pair of left and right rear wheels are arranged such that a toe angle is 5° or more and 30° or less,
The six-wheel electric vehicle according to claim 11. The pair of left and right rear wheels are
The sum of the angle formed by a line connecting the contact point of the left rear wheel and the ground with the left middle wheel and the ground with respect to the traveling direction and the toe angle of the rear wheel is 10° or more and 60° or less,
The sum of the angle formed by a line connecting the right rear wheel and the ground and the right middle wheel and the ground with respect to the traveling direction and the toe angle of the rear wheel is 10° or more and 60° or less. It is arranged like this,
The six-wheel electric vehicle according to claim 11 or 12. having a mechanism that can change the toe angle of the front wheels or the toe angle of the rear wheels according to the external environment;
The six-wheel electric vehicle according to any one of claims 5 to 13.

Images