Inverted pendulum type vehicle

The present invention relates to an inverted pendulum type vehicle, and relates to an inverted pendulum type vehicle having a main wheel and an auxiliary wheel for facilitating turning.

As an inverted pendulum type vehicle, a vehicle body frame, a main wheel formed by combining a plurality of rotatable driven rollers so that the rotation axes of the driven rollers form an annular shape, and the vehicle body frame and the rotation axis of the main wheels are approximately the same. Left and right drives equipped with a plurality of rotatable drive rollers that are coaxially supported so as to be located on both sides of the main wheel and are arranged so as to be in contact with the driven roller in a twisting relationship. An inverted pendulum type vehicle having a disk and a drive means for individually driving the left and right drive disks is known (for example, Patent Document 1).

The inverted pendulum type vehicle according to Patent Document 1 can be moved back and forth by rotating the left and right drive discs and rotating the main wheels around an axis extending left and right. Further, the inverted pendulum type vehicle can be moved to the left and right by rotating the left and right drive disks with a speed difference and rotating the driven roller. In this way, the inverted pendulum type vehicle can travel in any of the front, rear, left, and right directions.

<p num="0004"><patcit num="1"><text>Japanese Unexamined Patent Publication No. 2011-63243</text></patcit></p>

<p num="0005"> However, although the inverted pendulum type vehicle according to Patent Document 1 is good at moving back and forth and left and right, there is a problem that it is difficult to turn left and right (turning). To solve this problem, it is conceivable to provide an auxiliary wheel in addition to the main wheel and rotate the inverted pendulum type vehicle by the frictional force of the auxiliary wheel with the floor surface and the driving force of the auxiliary wheel. In such an inverted pendulum type vehicle, a configuration is conceivable in which the auxiliary wheels are supported by an auxiliary wheel arm provided so as to be rotatable in the vertical direction with respect to the vehicle body frame, and the auxiliary wheels are grounded by their own weight. However, in this configuration, assuming that some external force that pushes down the auxiliary wheel arm is applied to the auxiliary wheel arm, the auxiliary wheel is used to ensure the load bearing capacity of the rotating shaft of the secondary wheel and the support structure of the rotating shaft. Make it larger than necessary.</p><p num="0006"> The present invention has been made in view of the above background, and in an inverted pendulum type vehicle, even when an external force such as pushing down the auxiliary wheel arm is applied, an excessive load is applied to the auxiliary wheel. The challenge is not to join.</p>

<p num="0007"> In order to solve the above problems, the present invention relates to an inverted pendulum type vehicle (1) having a main wheel (3) movable back and forth and left and right and a body frame (2) supported by the main wheel. (2) has an auxiliary wheel arm (101) rotatably supported up and down, and an auxiliary wheel (5) supported by the auxiliary wheel arm and grounded, and the auxiliary wheel is deformable. It is supported via the urging device (129), urged at a predetermined position with respect to the sub-wheel arm, and when a downward load is applied to the sub-wheel arm, the urging device is deformed and said. It is characterized in that at least a part of the auxiliary wheel arm is in contact with the ground.</p><p num="0008"> According to this configuration, since the auxiliary wheel arm supporting the auxiliary wheel has a deformable urging device, the urging device is deformed when an external force such as pushing down the auxiliary wheel arm is applied. The secondary wheel arm hits the floor. Therefore, it is possible to prevent the load of pushing the auxiliary wheel arm toward the floor surface from being applied to the auxiliary wheel and the joint portion between the auxiliary wheel and the auxiliary wheel arm. As a result, the load bearing capacity required for the auxiliary wheel and the auxiliary wheel arm can be minimized, and the circumference of the auxiliary wheel can be made lightweight and compact.</p><p num="0009"> In the above invention, the auxiliary wheel arm may include at least one bendable joint (102, 116), and the urging device may urge the joint at a predetermined angle.</p><p num="0010"> According to this configuration, the deformed portion and the deformation direction of the sub-wheel arm are determined, and the support structure of the sub-wheel by the sub-wheel arm is stabilized.</p><p num="0011"> In the above invention, it is preferable that the endmost portion (R) of the auxiliary wheel, which is the farthest from the main wheel in the horizontal direction, is arranged above the joint portion in the vertical direction.</p><p num="0012"> According to this configuration, when the inverted pendulum type vehicle collides with an obstacle from the end end side of the auxiliary wheel while traveling, the auxiliary wheel side of the auxiliary wheel arm can smoothly rotate upward. The secondary wheel can move upward to smoothly overcome obstacles.</p><p num="0013"> In the above invention, it is preferable that the joint portion is located below the line segment (L1) connecting the rotation shaft (111) of the auxiliary wheel arm with respect to the vehicle body frame and the end end portion.</p><p num="0014"> According to this configuration, the direction of the downward load applied to the sub-wheel arm and the direction in which the joints of the sub-wheel arm protrude with respect to both ends of the sub-wheel arm coincide with each other, so that the vehicle body frame is the sub-wheel arm. The joints tend to bend smoothly when you press. Further, when a downward load is applied to the auxiliary wheel arm, the auxiliary wheel arm can be brought into contact with the floor surface at a relatively early stage. Further, when an obstacle on the floor surface comes into contact with the auxiliary wheel while the inverted pendulum type vehicle is running, the joint portion bends and the auxiliary wheel easily overcomes the obstacle.</p><p num="0015"> In the above invention, the auxiliary wheel arm is rotatably supported by the first auxiliary wheel arm (103) rotatably supported by the vehicle body frame and the first auxiliary wheel arm within a predetermined rotation range. It has a second sub-wheel arm (104), and the urging device is a spring (129) provided between the first sub-wheel arm and the second sub-wheel arm, and is a spring (129) of the second sub-wheel arm. It is preferable that the end portion on the auxiliary wheel side is urged toward the floor surface side with respect to the end portion on the first auxiliary wheel arm side.</p><p num="0016"> According to this configuration, the auxiliary wheel arm is formed in a simple configuration, is normally maintained at a position away from the floor surface when it is not loaded, and can be bent and grounded when it is loaded.</p><p num="0017"> In the above invention, the sub-wheel includes a wheel (151) rotatably supported by the sub-wheel arm and a plurality of free rollers rotatably supported on the outer peripheral portion of the wheel about a tangent line of the wheel. The wheel may be driven by an electric motor (133).</p><p num="0018"> According to this configuration, the inverted pendulum type vehicle can be turned by rotating the wheels of the secondary wheels. Further, since the auxiliary wheel has a free roller, the auxiliary wheel does not become a running resistance of the inverted pendulum type vehicle because the free roller rotates even when the wheel does not rotate.</p><p num="0019"> In the above invention, the joint portion may be arranged below the electric motor.</p><p num="0020"> According to this configuration, contact between the electric motor and the floor surface can be avoided even when the joint portion is bent. Further, when the joint portion is arranged so as to project downward with respect to both ends of the auxiliary wheel arm, the electric motor is arranged on the back side (upper side) of the protruding portion of the joint portion, so that the space can be effectively used. become.</p><p num="0021"> In the above invention, the auxiliary wheel arm may have a flexible and removable skid plate (120) at a portion that comes into contact with the vehicle body frame when the vehicle body frame is tilted toward the auxiliary wheel side.</p><p num="0022"> According to this configuration, since the auxiliary wheel arm touches the floor surface via the skid plate, slippage between the auxiliary wheel arm and the floor surface is suppressed. As a result, the auxiliary wheel arm can stably support the vehicle body frame with respect to the floor surface. Further, since the auxiliary wheel arm comes into contact with the floor surface via the skid plate, the floor surface is less likely to be scratched. Further, since the skid plate is removable, it can be replaced when it is worn.</p>

<p num="0023"> According to the above configuration, in the inverted pendulum type vehicle, even when a downward load is applied to the auxiliary wheel arm, an excessive load can be prevented from being applied to the auxiliary wheel.</p>

<figref num="1">Perspective view of an inverted pendulum type vehicle according to an embodiment</figref><figref num="2">Side view of an inverted pendulum type vehicle</figref><figref num="3">Side view of an inverted pendulum type vehicle with the wheel cover removed</figref><figref num="4">Front view of an inverted pendulum type vehicle shown with the wheel cover removed</figref><figref num="5">Perspective view of body frame</figref><figref num="6">Perspective view of the auxiliary wheel arm and auxiliary wheel unit (the electric motor, rotation angle sensor, and auxiliary wheel cover are omitted).</figref><figref num="7">Top view of the auxiliary wheel arm and auxiliary wheel unit (shown with the electric motor, rotation angle sensor and auxiliary wheel cover omitted)</figref><figref num="8">Cross-sectional view of the auxiliary wheel arm and auxiliary wheel unit in the initial form (the electric motor, rotation angle sensor, and auxiliary wheel cover are omitted).</figref><figref num="9">Cross-sectional view of the auxiliary wheel arm and auxiliary wheel unit in the post-bent form (the electric motor, rotation angle sensor, and auxiliary wheel cover are omitted).</figref><figref num="10">It is a side view of an inverted pendulum type vehicle, and shows a modified example of the first auxiliary wheel arm.</figref><figref num="11">Cross-sectional view of the auxiliary wheel arm and the auxiliary wheel unit in the initial form of the partially modified embodiment (the electric motor, the rotation angle sensor, and the auxiliary wheel cover are omitted).</figref><figref num="12">Cross-sectional view of the auxiliary wheel arm and the auxiliary wheel unit in the modified form of the partially modified embodiment (the electric motor, the rotation angle sensor, and the auxiliary wheel cover are omitted).</figref>

Hereinafter, embodiments of the inverted pendulum type vehicle of the present invention will be described with reference to the drawings. In the following explanation, each direction is determined based on the occupant (passenger) seated in the inverted pendulum type vehicle.

(overall structure) FIG. 1 is a perspective view of the inverted pendulum type vehicle according to the embodiment, FIG. 2 is a side view of the inverted pendulum type vehicle, and FIG. 3 is a side view of the inverted pendulum type vehicle with the wheel cover removed. FIG. 4 is a front view of an inverted pendulum type vehicle in which the step unit is in the retracted state and the wheel cover is removed. As shown in FIGS. 1 to 4, the inverted pendulum type vehicle 1 includes a vehicle body frame 2 forming a vehicle body skeleton, a main wheel unit 4 including a main wheel 3, an auxiliary wheel unit 6 including an auxiliary wheel 5, and a main wheel. A drive unit 7 for driving the unit 4, an electrical unit 8 for controlling the drive unit 7 and the auxiliary wheel unit 6, a battery pack 9 for supplying electric power to the electrical unit 8, and a saddle unit 11 for seating an occupant. Have.

(Body frame) FIG. 5 is a perspective view of the vehicle body frame. As shown in FIGS. 1 to 5, the vehicle body frame 2 has a pair of left and right side posts 21 extending vertically, and an upper beam 22 and a middle beam 23 extending left and right and connecting the left and right side posts 21. .. The upper beam 22 extends in a straight line, and both left and right ends are joined to the upper ends of the left and right side posts 21. The middle beam 23 is arranged below the upper beam 22, and both left and right ends are joined to the middle portion of the left and right side posts 21. The middle beam 23 is formed by being curved so that the middle portion in the longitudinal direction protrudes forward from both the left and right ends. The side post 21, upper beam 22, and middle beam 23 are made of steel pipe material and are joined to each other by bolting or welding. Hereinafter, unless otherwise specified, the term joining shall include known joining methods such as bolt fastening and welding. In other embodiments, the side post 21, upper beam 22, and middle beam 23 may be formed from known materials such as pressed steel sheets.

Mount members (axle support members) 26 supported by the axle 25 that supports the main wheel unit 4 are joined to the lower ends of the left and right side posts 21. The axle 25 and the mount member 26 form a part of the vehicle body frame 2. The mount member 26 has a mount base 31 having an axle hole (not shown), a post joint 32 extending upward from the mount base 31, and a step joint 33 extending downward from the mount base 31. .. The post joint portion 32 is joined to the lower end portion of each side post 21. The left and right axle holes are formed so as to penetrate to the left and right, and are arranged coaxially with each other. The inner diameter of the axle hole is formed to be smaller than the outer diameter of the axle 25. An axle fastening bolt 28 is inserted into the axle hole (see Fig. 4). The shaft portion of the axle fastening bolt 28 penetrates the washer 29 and the axle hole from the outside in the left-right direction, and is screwed to the end portion of the axle 25 to fasten the axle 25 to the mount member 26 in a non-rotatable manner. The left and right step joints 33 extend downward from the mount base 31 and then extend in the left-right direction so as to be separated from each other. A step unit 35, which will be described later, is hung between the lower ends of the left and right step joints 33.

A pair of left and right first brackets 37 are joined to the upper beam 22 so as to project forward, and a pair of left and right second brackets 38 are joined to the middle beam 23 so as to project forward. The drive unit 7 is bolted to the first and second brackets 37 and 38, and the drive unit 7 is arranged in front of the upper part of the left and right side posts 21.

A pair of left and right third brackets 39 are joined to the upper beam 22 so as to project rearward. A battery case 41 for supporting the battery pack 9 is joined to the third bracket 39, and the battery case 41 is arranged above and behind the left and right side posts 21. The battery case 41 is formed in a box shape that opens toward the rear, and has a connector (not shown) with the battery pack 9 inside. The battery pack 9 is supported by the battery case 41 and connected to the connector by being inserted into the battery case 41 from the rear.

An electrical unit joint 43, which is a bolt boss, is provided in the middle of the left and right side posts 21 in the vertical direction. An electrical case 44 forming the outer shell of the electrical unit 8 is bolted to the electrical unit joint 43, and the electrical case 44 is arranged directly below the battery case 41, that is, behind the upper part of the side post 21.

(Main wheel unit) As shown in FIG. 4, the main wheel unit 4 is arranged between the left and right mounting members 26 and between the left and right side posts 21. The main wheel unit 4 is inserted by an axle 25 extending horizontally in the vehicle width direction (left-right direction), left and right drive discs 50 rotatably supported on the outer periphery of the axle 25 independently of each other, and an axle 25. In addition, it has an annular main wheel 3 arranged between the left and right drive discs 50, and left and right driven pulleys 51 for cog belts joined to the left and right drive discs 50. The left and right drive disks 50 and the left and right driven pulleys 51 are all on the same axis with the axis of the axle 25 as the common axis. A pair of left and right step portions (not shown) are formed on the outer circumference of the axle 25 at predetermined intervals in the axial direction. The left and right drive disks 50 are held between a nut (not shown) screwed to the axle 25 and a step portion, and the position of the axle 25 in the axial direction is determined.

The main wheel 3 is a drive wheel driven based on an inverted pendulum control, and is composed of a metal ring member 53 and a plurality of driven rollers 54 (free rollers) attached to the outer circumference of the ring member 53. It is grounded at the driven roller 54. The driven roller 54 has a cylindrical metal base portion rotatably mounted on the outer circumference of the annular member 53 (reference numeral omitted) and a cylindrical rubber outer peripheral portion vulcanized and bonded to the outer circumference of the base portion (reference numeral omitted). Omitted) and. A plurality of driven rollers 54 are provided in the ring direction (circumferential direction) of the ring member 53, and can individually rotate (rotate) around the tangent line of the ring member 53 at its own arrangement position. .. That is, the main wheel 3 is formed by combining a plurality of driven rollers 54 that can rotate independently so as to form a ring. Strictly speaking, the plurality of driven rollers 54 form the main wheel 3 by combining them so as to form a polygon having an angular number corresponding to the number of the driven rollers 54.

The left and right drive disks 50 have a disk shape with an outer diameter smaller than the central radius of the ring member 53, and the outer peripheral portion thereof has a substantially conical trapezium shape. A plurality of metal drive rollers 58 are rotatably supported on the outer peripheral portion of the drive disk 50 at equal intervals in the circumferential direction. The drive roller 58 of the drive disk 50 on the left side and the drive roller 58 of the drive disk 50 on the right side are arranged symmetrically, and the rotation center of each drive roller 58 is twisted with respect to the rotation center of the drive disk 50. It is arranged so as to have a relationship of. As a result, the left and right drive rollers 58 have a symmetrical shape and are arranged in an inclined manner similar to the tooth streaks of the helical gear.

The left and right drive discs 50 are arranged so as to sandwich the main wheels 3 from both the left and right sides, and support the main wheels 3 on substantially the same axis (concentric). As a result, the main wheel 3 is supported between the left and right drive disks 50.

The outer peripheral portion of the drive roller 58 of the drive disc 50 is in contact with the outer peripheral portion of the driven roller 54 of the main wheel 3 in a pressed state. The drive rollers 58 of the left and right drive discs 50 sandwich the driven rollers 54 from both the left and right sides, so that the main wheel 3 is supported between the left and right drive discs 50 in a non-axial state, and is centered on itself together with the left and right drive discs 50. It can rotate (revolve) as a rotation axis. As described above, the assembly as the main wheel unit 4 is composed of the left and right drive disks 50, the left and right driven pulleys 51, the axle 25, and the main wheel 3. The main wheel unit 4 is arranged between the left and right mount members 26, penetrates the washer 29 and the axle hole, and is fastened to the inside of the mount member 26 by the axle fastening bolt 28 joined to the end of the axle 25. The head of the axle fastening bolt 28 projects outward from the mount member 26 to the left and right.

(Drive unit) The drive unit 7 includes a pair of left and right electric motors 61, a reduction mechanism 62, and a pair of left and right cog belt drive pulleys 63. The reduction mechanism 62 includes one gear case 64, a gear train for the left electric motor 61 supported in the gear case 64 (not shown), and a gear train for the right electric motor 61 supported in the gear case 64 (not shown). (Not shown). The left and right electric motors 61 are joined to the left and right sides of the gear case 64 so that their rotation axes are coaxial with each other with the gear case 64 interposed therebetween. The output shafts (not shown) of the two gear trains in the reduction mechanism 62 project coaxially with each other from the left and right sides of the gear case 64. The output shaft of each gear row is arranged parallel to the rotation shafts of the left and right electric motors 61, and the output shaft of the gear row corresponding to the left electric motor 61 protrudes to the left and corresponds to the right electric motor 61. The output shaft of the gear train is projected to the right. The drive pulley 63 is joined to the output shaft of each gear train.

The drive unit 7 is supported by the vehicle body frame 2 by bolting the gear case 64 to the first bracket 37 and the second bracket 38. The drive unit 7 is supported by the vehicle body frame 2, and the drive unit 7 is arranged in front of the upper part of the left and right side posts 21 and above the front part of the main wheel unit 4. The left and right electric motors 61 are arranged in front of the left and right side posts 21, and project outward from the left and right side posts 21. The left and right drive pulleys 63 are arranged forward and downward with respect to the left and right electric motors 61, and are arranged above the left and right driven pulleys 51. An endless cog belt 66 is hung on the drive pulley 63 and the driven pulley 51 that correspond to each other on the left and right sides. The drive pulley 63 has a smaller diameter and a smaller number of teeth than the driven pulley 51. As a result, the rotational force of the electric motor 61 on the left side is transmitted to the drive disk 50 on the left side via the gear train on the left side of the reduction mechanism 62, the driven pulley 51 on the left side, the cog belt 66, and the driven pulley 51 on the left side. Similarly, the rotational force of the electric motor 61 on the right side is transmitted to the drive disk 50 on the right side via the gear train on the right side of the reduction mechanism 62, the driven pulley 51 on the right side, the cog belt 66, and the driven pulley 51 on the right side.

A synthetic resin wheel cover 67 is provided so as to cover the main wheel 3, the left and right drive discs 50, the left and right driven pulleys 51, the left and right drive pulleys 63, and the cog belt 66. The lower part of the wheel cover 67 has an opening, and the lower part of the main wheel 3 is exposed to the outside.

(Step unit) As shown in FIGS. 1 to 4, the step unit 35 has a foot step 71 for supporting the sole of the occupant and a stand device 72 provided on the foot step 71. The stand device 72 is used to maintain the inverted pendulum type vehicle 1 in the upright state when the inverted pendulum is not controlled. The foot step 71 has a front end portion extending to the left and right in front of the wheel cover 67, and a pair of left and right side portions extending rearward from the left and right ends of the front end portion, respectively, and left and right at the rear end portion of each side portion. It is bolted to the step joint 33 of the mount member 26 of the above.

The stand device 72 includes a pair of left and right stand arms 74 that are rotatably supported by the foot step 71 between the standing position and the storage position, and a standing lever that rotates each stand arm 74 from the storage position to the standing position. It has 75 and a pair of left and right storage levers 76 that rotate each stand arm 74 from the standing position to the storage position. The standing lever 75 and the left and right storage levers 76 are rotatably supported by the foot step 71, and are connected to the pair of left and right stand arms 74 via each link member (reference numeral omitted). The occupant can rotate the stand arm 74 between the standing position and the storage position by depressing the standing lever 75 and the left and right storage levers 76. The left and right stand arms 74 come into contact with the floor surface S when the vehicle body frame 2 is tilted forward in the standing state.

(Saddle unit) As shown in FIGS. 1 to 4, the saddle unit 11 has a saddle 84 that supports the buttocks of the occupant and a saddle post 85 that supports the saddle 84 on the vehicle body frame 2. The saddle 84 has a plate-shaped base 86 forming a skeleton (bottom plate) and a flexible pad 87 attached to the upper part of the base 86. The pair of left and right saddle posts 85 form a column extending vertically, and the upper end thereof is joined to the lower part of the base 86. The left and right saddle posts 85 are inserted into the upper end openings of the left and right side posts 21 and supported by the side posts 21. Adjusting screws 88 that penetrate the side posts 21 in the radial direction are screwed near the upper ends of the left and right side posts 21. The left and right saddle posts 85 are formed with receiving holes (not shown) that penetrate in the radial direction and receive the adjusting screw 88. A plurality of receiving holes are formed along the longitudinal direction of the saddle post 85. The insertion depth of the saddle post 85 relative to the side post 21 is selected by selecting the receiving hole through which the adjusting screw 88 passes. That is, the height of the saddle 84 with respect to the side post 21 can be adjusted.

(Electrical unit) The electrical unit 8 has a main wheel PDU, a sub wheel PDU, a DC-DC converter, an I / O interface, and a gyro sensor 91, all of which are not shown. The main wheel PDU is a main wheel control power drive unit for controlling the drive unit 7, and the sub wheel PDU is a sub wheel control power drive unit for controlling the sub wheel unit 6. The DC-DC converter steps down the DC voltage supplied from the battery pack 9 to a predetermined DC voltage. The gyro sensor 91 detects the inclination angle and the angular velocity of the vehicle body frame 2 with respect to a predetermined axis (for example, a vertical line). The main wheel PDU, secondary wheel PDU, DC-DC converter, and I / O interface are housed in a box-shaped electrical case 44 (see FIG. 1).

The electrical case 44 is bolted to the electrical unit joints 43 provided on the left and right side posts 21, and is arranged below the battery case 41 and above the main wheel unit 4. When viewed from the side, most of the electrical case 44 is arranged behind the left and right side posts 21. The gyro sensor 91 is joined to the bottom surface of the electrical case 44, and is arranged between the electrical case 44 and the main wheel unit 4 in the vertical direction. The switch button 93 for turning on / off the power of the electrical unit 8 is provided on the front surface of the wheel cover 67, that is, on the front upper side of the main wheel 3. The output signal from the switch button 93 is input to the I / O interface.

(Secondary wheel unit) FIG. 5 is a perspective view of the vehicle body frame, FIG. 6 is a perspective view of the auxiliary wheel arm and the auxiliary wheel unit (the electric motor, the rotation angle sensor, and the auxiliary wheel cover are omitted), and FIG. 7 is the auxiliary wheel arm. It is a plan view of the auxiliary wheel unit (the electric motor, the rotation angle sensor and the auxiliary wheel cover are omitted). As shown in FIGS. 5 to 7, the auxiliary wheel unit 6 is supported by the axle fastening bolt 28 (axle 25) via the auxiliary wheel arm 101. The auxiliary wheel arm 101 has a first auxiliary wheel arm 103 and a second auxiliary wheel arm 104 that are flexibly connected to each other via a joint portion 102.

The first auxiliary wheel arm 103 includes a first auxiliary wheel arm front portion 106 formed of a metal pipe material and a first auxiliary wheel arm rear portion 107 which is a bracket joined to the first auxiliary wheel arm front portion 106. have. The front portion 106 of the first auxiliary wheel arm has a U-shape in which the intermediate portion in the longitudinal direction extends in the left-right direction, the left and right ends bend with respect to the intermediate portion and extend forward, and the front portion opens toward the front in a plan view. Present. The left and right front ends of the first auxiliary wheel arm front portion 106 are crushed in a plate shape from the left and right directions to form a surface facing left and right. Bearing holes (not shown) penetrating in the left-right direction are formed at each of the left and right front ends of the first auxiliary wheel arm front portion 106. A rotating shaft 111 joined to the head of the axle fastening bolt 28 is inserted into each bearing hole. The rotating shaft 111 is a stepped bolt having a shaft portion and a stepped head, and is coaxially screwed to the head of the axle fastening bolt 28. As a result, the front portion 106 of the first auxiliary wheel arm is rotatably supported by the axle 25 via the left and right rotating shafts 111 about the axis passing through the center of the axle 25. As a result, the main wheel unit 4 (left and right drive discs 50 and main wheel 3), the wheel cover 67, and the left and right mounting members 26 are arranged between the left and right front ends of the first auxiliary wheel arm front portion 106. .. Specifically, the front portion 106 of the first auxiliary wheel arm is supported by the head portion of the rotating shaft 111. The front portion 106 of the first auxiliary wheel arm is locked to a step portion formed on the head portion of the rotating shaft 111, and is supported so as not to be displaced in the axial direction with respect to the rotating shaft 111. That is, the front portion 106 of the first auxiliary wheel arm is supported so as not to fall off from the head portion of the rotating shaft 111.

The rear portion 107 of the first auxiliary wheel arm has a plate-shaped bottom portion 114 and left and right side wall portions 115 extending upward from the left and right side edges of the bottom portion 114. The rear portion 107 of the first auxiliary wheel arm is formed by press-molding a steel plate. The front ends of the bottom portion 114 and the left and right side wall portions 115 are welded to the rear end portion of the first auxiliary wheel arm front portion 106, that is, the intermediate portion in the longitudinal direction. The bottom portion 114 and the left and right side wall portions 115 extend rearward from the rear end portion of the first auxiliary wheel arm front portion 106. The bottom portion 114 extends rearward from the left and right side wall portions 115. A columnar support shaft 116 is hung between the left and right side wall portions 115. The support shaft 116 is arranged so that the axis extends to the left and right.

The second auxiliary wheel arm 104 is configured by joining the front portion 121 of the second auxiliary wheel arm and the rear portion 122 of the second auxiliary wheel arm to each other. The front portion 121 of the second auxiliary wheel arm is formed by bending a plate piece, and has an intermediate portion 124 having a surface facing forward and backward and extending left and right, and an intermediate portion 124 extending forward from both left and right ends of the intermediate portion 124, and the surfaces are left and right. It has left and right side portions 125 facing. Through holes (not shown) penetrating left and right are formed at the front ends of the left and right side portions 125, and a support shaft 116 is inserted through each through hole. As a result, the front portion 121 of the second auxiliary wheel arm is rotatably supported by the support shaft 116. In this way, the rear portion 107 of the first auxiliary wheel arm and the front portion 121 of the second auxiliary wheel arm form the joint portion 102.

A skid plate 120 is detachably attached to the lower surface of the bottom 114 of the rear portion 107 of the first auxiliary wheel arm. The skid plate 120 is a flexible plate-like member and is provided so as to cover the lower surface of the bottom 114. The bottom 114 is formed with engaging holes 118 penetrating vertically, and the skid plate 120 is provided with elastic claws 130 that are detachably locked to the engaging holes 118.

The lower end of the plate-shaped second auxiliary wheel arm rear portion 122 is fastened to the intermediate portion 124 of the second auxiliary wheel arm front portion 121 by a bolt 126. The bolt 126 is provided so as to penetrate the intermediate portion 124 of the front portion 121 of the second auxiliary wheel arm and screw into the rear portion 122 of the second auxiliary wheel arm, and the head of the bolt 126 is provided on the front side of the intermediate portion 124. It protrudes into.

The support shaft 116 supports the coil portion of the spring 129, which is a torsion coil spring. One end of the spring 129 is in contact with the upper surface of the bottom 114 of the rear portion 107 of the first auxiliary wheel arm, and the other end of the spring 129 is a bolt 126 integrally connected to the front portion 121 of the second auxiliary wheel arm and the rear portion 122 of the second auxiliary wheel arm. It is caught on the upper part of the head of. Based on the state of the inverted pendulum type vehicle 1 viewed from the left side (see FIG. 8), the front portion 121 of the second auxiliary wheel arm has the support shaft 116 with respect to the rear portion 107 of the first auxiliary wheel arm by the spring 129. It is urged clockwise as the center. That is, the rear end portion of the second auxiliary wheel arm front portion 121 supported by the support shaft 116 at the front end portion is urged by the spring 129 so as to face downward with respect to the support shaft 116. The front portion 121 of the second auxiliary wheel arm urged by the spring 129 is maintained in a state in which the lower edges of the left and right side portions 125 are in contact with the upper surface of the bottom portion 114 of the rear portion 107 of the first auxiliary wheel arm.

The lower end of the second auxiliary wheel arm rear portion 122 is bolted to the intermediate portion 124 of the second auxiliary wheel arm front portion 121 and extends upward with respect to the intermediate portion 124 of the second auxiliary wheel arm front portion 121. There is. The rear portion 122 of the second auxiliary wheel arm is formed in a plate shape whose surface faces the front and rear, and an insertion hole 131 penetrating the front and rear is formed in the central portion thereof.

The auxiliary wheel unit 6 includes an electric motor 133, a speed reducer 134, and an auxiliary wheel 5. The electric motor 133 has a housing (yoke) 137 in which a coil (not shown) is housed, and a rotating shaft 138 rotatably supported by the housing 137. The housing 137 is joined to the front surface of the rear portion 122 of the second auxiliary wheel arm by bolts or the like, and is arranged above the joint portion 102. The rotating shaft 138 of the electric motor 133 passes through the insertion hole 131 and projects rearward from the rear portion 122 of the second auxiliary wheel arm. A rotation angle sensor 139 for detecting the rotation angle of the rotation shaft 138 of the electric motor 133 is attached to the front end of the housing 137 of the electric motor 133.

The speed reducer 134 has a gearbox 141 forming an outer shell. The gearbox 141 has a main body portion 142 formed in a bottomed cylindrical shape, and a flange portion 143 projecting outward from the open end of the main body portion 142. The gear box 141 is joined to the rear surface of the rear portion 122 of the second auxiliary wheel arm at the flange portion 143, and the inside of the main body portion 142 communicates with the insertion hole 131. A gear train (not shown) is housed inside the main body 142. The gear train is composed of a plurality of spur gears and planetary gears, and is configured so that a predetermined reduction ratio can be obtained. The output shaft 145 of the speed reducer 134 connected to the gear train projects rearward from the main body 142 along the axis of the main body 142. The tip of the output shaft 145 is formed in a flat shape.

The auxiliary wheel 5 is a so-called omni wheel having one wheel 151 and a plurality of free rollers 153 rotatably supported on the outer peripheral portion of the wheel 151 via a support shaft 152. The wheel 151 has a front plate 157 and a rear portion that sandwich the front half portion 155 and the latter half portion 156 divided in half by a plane orthogonal to the rotation axis, and the front half portion 155 and the second half portion 156 from the direction along the rotation axis. It has a plate 158. The front plate 157, the front half portion 155, the rear portion 156, and the rear plate 158 are integrally connected by a plurality of bolts 161 penetrating them back and forth and a nut 162 screwed to the tip of each bolt 161. There is.

Grooves 164 and 165 for receiving the free roller 153 are formed on the mating surfaces of the first half portion 155 and the second half portion 156. The free roller 153 is rotatably supported by a support shaft 152 inserted in the central portion, and both ends of the support shaft 152 are sandwiched between the front half portion 155 and the rear half portion 156. In this way, the free roller 153 is rotatably supported by the wheel 151 via the support shaft 152. The axis of each support shaft 152 is arranged on the outer peripheral portion of the wheel 151 in parallel with the tangent line of the wheel 151 at each position. That is, the rotation axis of the free roller 153 is arranged parallel to the tangent line of the wheel 151 at the position where each of the free rollers 153 is provided.

The front plate 157, the front half 155, and the rear half 156 are formed with a receiving hole 168 penetrating back and forth in the central portion thereof. On the other hand, the rear plate 158 does not have a through hole in the central portion and constitutes the bottom portion of the receiving hole 168. The main body 142 of the speed reducer 134 is inserted into the receiving hole 168 through a gap, and the output shaft 145 of the speed reducer 134 is press-fitted into the coupling hole formed in the center of the rear plate 158. As a result, the output shaft 145 is coupled to the rear plate 158 so as to rotate integrally.

A support 171 is joined to the flange portion 143 of the gear box 141, and the auxiliary wheel cover 172 is supported by the support 171 (see FIGS. 1 and 2). The auxiliary wheel cover 172 is provided so as to cover the upper side of the auxiliary wheel 5 and the rear left and right sides.

As shown in FIG. 8, when the first auxiliary wheel arm 103 rotates with respect to the axle 25, the auxiliary wheel 5 comes into contact with the floor surface S on the free roller 153. The same applies when the vehicle body frame 2 is tilted within a predetermined range. At this time, the joint portion 102 is urged by the spring 129, and the lower edges of the left and right side portions 125 of the second auxiliary wheel arm front portion 121 are in contact with the upper surface of the bottom portion 114 of the first auxiliary wheel arm rear portion 107. Is maintained at. In this state, the front portion 106 of the first auxiliary wheel arm extends rearwardly and downwardly from the axle 25, and the bottom portion 114 of the rear portion 107 of the first auxiliary wheel arm extends substantially horizontally rearward. At this time, the auxiliary wheel arm 101 including the first auxiliary wheel arm 103 and the second auxiliary wheel arm 104 is arranged away from the floor surface S. The form of the auxiliary wheel arm at this time is called the initial form. Further, when the auxiliary wheel 5 is in contact with the ground, the rotation axis 138 of the electric motor 133, that is, the rotation axis of the wheel 151 extends back and forth. That is, the wheel 151 rotates about an axis orthogonal to the axis of the axle 25 (the center axis of rotation of the main wheel 3) in a plan view.

As shown in FIGS. 1 and 6, the left and right side posts 21 are provided with stoppers 175 that project rearward and downward. The stopper 175 abuts on the upper surface of the front portion 106 of the first auxiliary wheel arm when the auxiliary wheel arm 101 is in a predetermined rotation position about the axle 25 extending in the left-right direction, so that the stopper 175 is located around the axle 25. 1 Regulate the upward rotation range of the auxiliary wheel arm 103 (the rotation range of the first auxiliary wheel arm 103 in the counterclockwise direction when the vehicle is viewed from the left (see FIGS. 2 and 3)). .. In other words, when the stopper 175 abuts on the first auxiliary wheel arm 103, the maximum rearward inclination angle of the vehicle body frame 2 (side post 21) is regulated.

(Attitude and running control of inverted pendulum type vehicle) The running operation of the inverted pendulum type vehicle 1 will be described. The main wheel PDU calculates the position of the center of gravity of the entire inverted pendulum type vehicle 1 including the occupant seated in the saddle unit 11 at any time from the changes in the tilt angle and the angular velocity of the vehicle body frame 2 measured by the gyro sensor 91.

When the center of gravity of the entire inverted pendulum type vehicle 1 including the occupant is in the neutral position (for example, above the axle 25), the main wheel PDU is based on the control process according to the inverted pendulum control law, and the electric motor 61 of the drive unit 7. To keep the body frame 2 in an upright position.

At this time, the sub-wheel PDU keeps the electric motor 133 of the sub-wheel unit 6 in the stopped state based on the control process according to the turning control rule, and the sub-wheel 5 does not rotate.

When the center of gravity of the entire inverted pendulum type vehicle 1 including the occupant moves to the front side from the neutral position, the main wheel PDU moves the electric motor 61 of the drive unit 7 in the forward rotation direction under the control process according to the inverted pendulum control rule. Drive at the same speed. By driving the electric motor 61, the left and right drive disks 50 rotate forward at the same speed, and the main wheel 3 revolves forward with its own wheel center as the rotation axis, that is, revolves in the forward direction. At this time, since there is no difference in rotational speed between the left and right drive disks 50, the drive roller 58 of the drive disk 50 and the driven roller 54 of the main wheel 3 do not rotate, and the inverted pendulum type vehicle 1 moves straight forward.

When the center of gravity of the entire inverted pendulum type vehicle 1 including the occupants moves to the rear side from the neutral position, the main wheel PDU moves the electric motors 61 of the left and right drive units 7 under the control process according to the inverted pendulum control law. Drive at the same speed in the reverse direction. By driving the electric motor 61, the left and right drive disks 50 are reversed at the same speed, and the main wheel 3 is reversed with its own wheel center as the rotation axis, that is, it revolves in the reverse direction. At this time, since there is no difference in rotational speed between the left and right drive disks 50, the drive roller 58 of the drive disk 50 and the driven roller 54 of the main wheel 3 do not rotate, and the inverted pendulum type vehicle 1 moves backward straight.

When moving forward and backward, the sub-wheel PDU maintains the stopped state of the electric motor 133 of the sub-wheel unit 6 under the control process according to the turning control law, and the sub-wheel 5 does not revolve. At this time, the free roller 153 of the auxiliary wheel 5 rotates as the inverted pendulum type vehicle 1 advances.

When the center of gravity of the entire inverted pendulum type vehicle 1 including the occupants moves to the left or right side of the neutral position, the main wheel PDU sets the electric motor 61 of the drive unit 7 under the control process according to the inverted pendulum control rule. It is driven in different rotation directions and / or rotation speeds. Due to the drive of the electric motor 61, a difference in rotational speed is generated between the left and right drive disks 50, and the component force in the direction orthogonal to this force with respect to the force in the circumferential (tangential) direction due to the rotational force of the left and right drive disks 50. It acts on the contact surface between the left and right drive rollers 58 and the driven rollers 54 of the main wheel 3. Due to this component force, the driven roller 54 rotates (rotates) around its own central axis.

The rotation of the driven roller 54 is determined by the difference in rotation speed between the left and right drive disks 50. For example, when the left and right drive disks 50 are rotated in opposite directions at the same speed, the main wheel 3 does not revolve at all, and only the driven roller 54 rotates. As a result, a running force in the left-right direction is applied to the main wheel 3, and the inverted pendulum type vehicle 1 moves in the left-right direction (moves sideways). Further, when the left and right drive disks 50 are rotated in the same direction at different speeds, the driven roller 54 rotates along with the revolution of the main wheel 3. As a result, the inverted pendulum type vehicle 1 moves diagonally forward and diagonally backward.

At this time, the sub-wheel PDU drives the electric motor 133 of the sub-wheel unit 6 under the control process according to the turning control law, and rotates the sub-wheel 5 at a rotation speed equivalent to the lateral movement speed (revolution). You may let me. When there is a difference between the amount of movement due to the rotation of the driven roller 54 of the main wheel 3 and the amount of movement due to the rotation of the auxiliary wheel 5, the inverted pendulum type vehicle 1 turns.

When the inverted pendulum control is performed, the forward tilt and the backward tilt of the vehicle body frame 2 centering on the axle 25 are kept within a predetermined range, so that the first auxiliary wheel arm 103 does not come into contact with the stopper 175. On the other hand, when the inverted pendulum control is not performed (for example, when the vehicle is stopped), the vehicle body frame 2 can freely rotate around the axle 25 extending to the left and right, so that the vehicle body frame 2 exceeds a predetermined range. Can lean backwards. When the vehicle body frame 2 tilts backward, the stopper 175 comes into contact with the first auxiliary wheel arm 103 and pushes the first auxiliary wheel arm 103 downward. As a result, the joint portion 102 bends around the support shaft 116 extending in the left-right direction against the urging force of the spring 129 (the support in which the second auxiliary wheel arm 104 extends in the left-right direction with respect to the first auxiliary wheel arm 103). Rotates around axis 116). FIG. 9 is a cross-sectional view of the auxiliary wheel arm and the auxiliary wheel unit in the post-bent form (the electric motor, the rotation angle sensor, and the auxiliary wheel cover are omitted). As shown in FIG. 9, as the vehicle body frame 2 tilts backward, the bottom 114 of the rear portion 107 of the first auxiliary wheel arm abuts on the floor surface S via the skid plate 120. The form of the auxiliary wheel arm 101 in the bent state at this time is referred to as a post-bent form. In this state, the backward tilt of the vehicle body frame 2 is restricted. In other words, the body frame 2 is maintained at a predetermined angle with respect to the floor surface S by the first auxiliary wheel arm 103 as a support.

As described above, when the vehicle body frame 2 tilts backward, the auxiliary wheel arm 101 bends at the joint portion 102, and the bottom portion 114 of the first auxiliary wheel arm rear portion 107 abuts on the floor surface S. It is possible to avoid applying a load to the auxiliary wheel unit 6. Specifically, the output shaft 145 of the speed reducer 134, the rotating shaft 138 of the electric motor 133, the joint between the rear part 122 of the second auxiliary wheel arm and the housing 137 and the gearbox 141 of the electric motor 133, and the output shaft 145 of the speed reducer 134. And the joint with the rear plate 158 of the auxiliary wheel 5 are avoided. Therefore, the load capacity required for the auxiliary wheel unit 6 can be minimized.

The joint portion 102 of the auxiliary wheel arm 101 is arranged below the line segment connecting the front end portion supported by the axle 25 of the auxiliary wheel arm 101 and the rear end portion supporting the electric motor 133. 1 When the auxiliary wheel arm 103 is pushed downward by the stopper 175 of the vehicle body frame 2, the joint portion 102 can rotate smoothly. Further, when an obstacle on the road surface hits the auxiliary wheel 5 while the inverted pendulum type vehicle 1 is traveling, the auxiliary wheel arm 101 and the joint portion 102 rotate so that the auxiliary wheel 5 smoothly overcomes the obstacle. Can be done.

Further, as shown in FIG. 2, the rearmost end portion R of the auxiliary wheel unit 6 farthest rearward from the main wheel 3 in the horizontal direction is composed of the auxiliary wheel cover 172. The horizontal line passing through the rearmost end portion R is defined as the horizontal line H, and the line segment connecting the rearmost end portion R and the center of the rotation shaft 111 is defined as L1. The joint portion 102 has the horizontal line H and the line segment arranged below L1. Therefore, when the inverted pendulum type vehicle 1 moves backward and an obstacle on the floor surface S collides with the rearmost end portion R of the auxiliary wheel unit 6 from the rear of the auxiliary wheel unit 6, the joint portion 102 is the center. Since the auxiliary wheel unit 6 side can smoothly rotate upward, it contributes to shock absorption.

When the vehicle body frame 2 rotates forward about the axle 25 from the rearward tilted state, the joint portion 102 of the auxiliary wheel arm 101 is urged by the spring 129, and the left and right side portions 125 of the second auxiliary wheel arm front portion 121. Rotates until it comes into contact with the bottom 114 of the rear portion 107 of the first auxiliary wheel arm, and the bottom 114 of the rear portion 107 of the first auxiliary wheel arm separates from the floor surface S and returns to the initial form.

Next, with reference to FIG. 10, as a modified example of the first auxiliary wheel arm 103, an example in which a guard 180 for protecting the auxiliary wheel unit 6 is provided on the first auxiliary wheel arm 103 will be described. FIG. 10 is a side view of the inverted pendulum type vehicle 1 and shows a modified example of the first auxiliary wheel arm 103. As shown in FIG. 10, the guard 180 is a member that projects substantially horizontally rearward from the front portion 106 of the first auxiliary wheel arm. The guard 180 is formed of, for example, a pipe material, has a U-shape in a plan view, and has a bifurcated front end. The guard 180 is joined to the left and right sides of the front portion 106 of the first auxiliary wheel arm at each front end by welding or the like. As a result, the main wheel unit 4 and the wheel cover 67 are arranged between the bifurcated front ends of the guard 180, and the rear portion of the guard 180 is arranged behind the main wheel unit 4.

The rear part of the guard 180 extends so as to cover the upper part of the auxiliary wheel unit 6. A diagonal member 181 is hung between the front portion of the guard 180 and the front portion 106 of the first auxiliary wheel arm, and the joint portion between the front portion of the guard 180 and the front portion 106 of the first auxiliary wheel arm is reinforced. The front-rear position of the guard 180 with respect to the auxiliary wheel unit 6 at the rearmost end is not particularly limited, but is preferably arranged in front of the rearmost end R. The guard 180 is arranged at a position where it does not come into contact with the auxiliary wheel unit 6 when the joint portion 102 bends.

By covering the upper part of the auxiliary wheel unit 6 with the guard 180, it is possible to prevent the load from being applied to the auxiliary wheel unit 6 from above the auxiliary wheel unit 6. For example, when a person's foot or the like approaches the auxiliary wheel unit 6 from above, the foot is blocked by the guard 180, and the auxiliary wheel unit 6 is prevented from being directly stepped on. The load from the foot is applied to the first auxiliary wheel arm 103 via the guard 180 and the diagonal member 181, and the first auxiliary wheel arm 103 touches the floor by bending the joint portion 102.

When the guard 180 is provided, the support 171 may be omitted and the auxiliary wheel cover 172 may be supported by the guard 180. In this case, when the joint portion 102 bends, the tail wheel 5 moves relative to the auxiliary wheel cover 172.

Next, a partially modified embodiment in which a part of the above embodiment is modified will be described with reference to FIGS. 11 and 12. FIG. 11 is a cross-sectional view of the sub-wheel arm and the sub-wheel unit in the initial form of the partially deformed embodiment (the electric motor, the rotation angle sensor, and the sub-wheel cover are omitted), and FIG. 12 shows the partial deformation. It is sectional drawing of the auxiliary wheel arm and the auxiliary wheel unit in the modified form (the electric motor, the rotation angle sensor and the auxiliary wheel cover are omitted). As shown in FIG. 11, the sub-wheel arm 200 according to the partially modified embodiment does not have the joint portion 102, and the first sub-wheel arm 103 and the second sub-wheel arm are provided by a plurality of springs 201 (biasing devices). 104 is connected. Among the configurations of the auxiliary wheel arm 200 according to the partially modified embodiment, the same configurations as those of the above-described embodiment are designated by the same reference numerals and the description thereof will be omitted.

The second sub-wheel arm 104 does not have the second sub-wheel arm front portion 121, but has a vertical wall portion 205 corresponding to the second sub-wheel arm rear portion 122. Similar to the rear portion 122 of the second auxiliary wheel arm, the vertical wall portion 205 is formed in a plate shape whose surface faces the front and rear, and an insertion hole 131 penetrating the front and rear is formed in the central portion thereof. The housing 137 of the electric motor 133 and the flange portion 143 of the gearbox 141 are joined to the vertical wall portion 205. A lower plate portion 206 extending forward below the electric motor 133 and the rotation angle sensor 139 is projected from the lower portion of the vertical wall portion 205. The lower plate portion 206 is arranged so that the surface faces up and down, and the reinforcing wall portion 207 spanning the vertical wall portion 205 and the lower plate portion 206 suppresses the fall of the lower plate portion 205 with respect to the vertical wall portion 205.

The lower plate portion 206 is arranged so as to face the bottom portion 114 of the first auxiliary wheel arm 103. A plurality of springs 201, which are coil springs, are interposed between the lower plate portion 206 and the bottom portion 114. One end of each spring 201 is joined to the lower surface of the lower plate portion 206, and the other end is joined to the upper surface of the bottom portion 114. With the above configuration, the first auxiliary wheel arm 103 and the second auxiliary wheel arm 104 are joined to each other via a spring 201.

As shown in FIG. 11, when the first sub-wheel arm 103 is not pushed by the stopper 175, the sub-wheel arm 101 including the first sub-wheel arm 103 and the second sub-wheel arm 104 separates from the floor surface S and is subordinate. The wheel 5 is in contact with the floor surface S due to its own weight. As shown in FIG. 12, when the vehicle body frame 2 tilts backward and the stopper 175 pushes the first auxiliary wheel arm 103 downward, each spring 201 is deformed, and the first auxiliary wheel arm 103 passes through the skid plate 120. It hits the floor surface S. Therefore, it is possible to avoid applying the load of the vehicle body frame 2 to the auxiliary wheel unit 6 as in the above-described embodiment. In this way, even when the joint portion 102 is not provided, the sub-wheel unit 6 is supported by the first sub-wheel arm 103 via the deformable spring 102 and the second sub-wheel arm 104, so that the vehicle body frame 2 can be used. The load of is not applied to the auxiliary wheel unit 6.

In the above partially modified embodiment, the lower plate portion 206 is provided on the second auxiliary wheel arm 104, and one end of the spring 201 is joined to the lower plate portion 206, but in other embodiments, the lower plate portion 206 is provided. Omitted, one end of the spring 201 may be directly joined to the housing 137 of the electric motor 133 or the element of the auxiliary wheel unit 6 such as the gearbox 141. In this case, the second auxiliary wheel arm 104 including the vertical wall portion 205 may be omitted, and the housing 137 of the electric motor 133 and the gear box 141 may be directly joined to each other.

Although the embodiments of the present invention have been described above, the present invention can be appropriately modified without departing from the spirit of the present invention. In the above embodiment, the configuration in which the sub-wheel 5 is arranged behind the main wheel 3 has been described, but the sub-wheel is not limited to the rear of the main wheel 3, but is arranged on the left and right sides or the front of the main wheel 3 to the side. It may be a wheel or a front wheel. That is, the position of the auxiliary wheel with respect to the main wheel 3 is not limited as long as it can generate a frictional force with the floor surface S at a position away from the main wheel 3 when the inverted pendulum type vehicle 1 turns. .. Further, it is preferable that the auxiliary wheels reduce the frictional force generated between the auxiliary wheels and the floor surface S when the inverted pendulum type vehicle 1 does not turn, and do not become the running resistance of the inverted pendulum type vehicle 1. Therefore, it is preferable to have the free roller 153 like the auxiliary wheel 5 of the above embodiment.

In the above embodiment, the state in which the bottom 114 of the rear portion 107 of the first auxiliary wheel arm and the left and right side portions 125 of the front portion 121 of the second auxiliary wheel arm are in contact with each other by the urging force of the spring 129 is defined as the initial form of the joint portion 102. However, in other embodiments, by using a tension coil spring, the joint portion 102 is maintained in a state where the first auxiliary wheel arm 103 and the second auxiliary wheel arm 104 do not come into contact with each other, and this state is set as the initial form. May be good. For example, the first auxiliary wheel arm 103 and the second auxiliary wheel arm 104 may be provided with portions facing each other in the left-right direction, and a tension coil spring extending in the left-right direction may be hung between the portions facing each other. .. With this configuration, the joint portion 102 can rotate in any direction of rotation about the support shaft 116 from the initial form.

Further, in the above embodiment, one joint portion 102 is provided on the auxiliary wheel arm 101, but in other embodiments, a plurality of joint portions 102 may be provided.

Further, in the partially modified embodiment, instead of the spring 201 which is a coil spring, an elastic body (elastomer) such as rubber or a leaf spring having appropriate spring characteristics may be applied.

1 ... Inverted pendulum type vehicle, 2 ... Body frame, 3 ... Main wheel, 4 ... Main wheel unit, 5 ... Secondary wheel, 6 ... Secondary wheel unit, 7 ... Drive unit, 8 ... electrical unit, 9 ... battery pack, 11 ... saddle unit, 21 ... side post, 25 ... axle, 50 ... drive disc, 54 ... driven roller , 58 ... drive roller, 61 ... electric motor, 62 ... reduction mechanism, 67 ... wheel cover, 71 ... foot step, 101 ... auxiliary wheel arm, 102 ... joint , 103 ... 1st sub-wheel arm, 104 ... 2nd sub-wheel arm, 106 ... 1st sub-wheel arm front, 107 ... 1st sub-wheel arm rear, 114 ... bottom, 115 ... Side wall, 116 ... Support shaft, 120 ... Skid plate, 121 ... Second secondary wheel arm front, 122 ... Second secondary wheel arm rear, 124 ... Middle , 125 ... Side, 129 ... Spring (Axle), 131 ... Insertion Hole, 133 ... Electric Motor, 134 ... Reducer, 138 ... Rotating Shaft, 141 .. Gearbox, 145 ... Output shaft, 151 ... Wheel, 153 ... Free roller, 172 ... Auxiliary wheel cover, 175 ... Stopper