1. A carrier, the carrier comprising:

a carrier main frame;

a travel unit disposed on the vehicle frame and configured to travel on a floor surface;

a seat vertically movably supported by the vehicle main frame;

a lifting unit provided between the seat and the carrier main frame to move the seat between a high position and a low position; and

a support leg extending generally downward from the seat and configured to ground when the seat is in the lowered position,

wherein the support legs are movable between a retracted position positioned proximate to the vehicle frame and a deployed position positioned away from the vehicle frame, the support legs being configured to be in the retracted position when the seat is in the raised position and to move from the retracted position to the deployed position when the seat is moved from the raised position to the lowered position.

2. The carrier of claim 1, wherein the support leg comprises: a first member pivotally connected to the seat at an upper end thereof to be movable between the retracted position and the deployed position; a first ground engaging member disposed at a lower end of the first member and configured to be grounded on the floor surface in a manner movable along the floor surface; and a first biasing member urging the first member toward the retracted position, the first member being configured to move from the retracted position to the deployed position against a biasing force of the first biasing member by a reaction force applied to the first ground contacting member from the floor surface.

3. The vehicle of claim 2, wherein the support leg further comprises a first damper disposed between the first member and the seat.

4. The vehicle of claim 2, wherein the first member is positioned at a front of the vehicle and is provided with a footrest.

5. The vehicle of claim 4, wherein the first ground engaging member is disposed directly below the footrest.

6. The carrier of claim 1, wherein the support leg comprises:

a second member pivotally supported by the seat at an upper end thereof to be movable between the retracted position and the deployed position;

a second ground engaging member disposed at a lower end of the second member and configured to be grounded on the floor surface in a manner movable along the floor surface;

a third member pivotally supported by an intermediate portion of the second member at an upper end of the third member and extending downward in a space defined between the vehicle frame and the second member;

a third ground engaging member disposed at a lower end of the third member and configured to be grounded on the floor surface in a manner movable along the floor surface; and

a second biasing member urging a lower portion of the third member downward away from the carrier frame.

7. The carrier of claim 6, wherein the second ground-contacting member comprises a second roller rotatably supported by the second member, and the third ground-contacting member comprises a third roller having a larger diameter than the second roller and rotatably supported by the third member.

8. The vehicle of claim 7, wherein the support leg further comprises a second damper disposed between the third member and the seat.

9. The vehicle according to claim 1, wherein the travel unit is provided with a drive wheel, and the drive wheel is driven under inverted pendulum control.

Background

JP5922489B discloses a vehicle having a travel unit and a seat supported by a drive unit via a lifting unit. The traveling unit is provided with a drive wheel, which is driven under inverted pendulum control.

The vehicle disclosed in JP5922489B may become unable to continue the inverted pendulum control when the remaining capacity of the battery falls below a certain level or in the event of any malfunction of the vehicle. In such a situation, the vehicle occupant must prevent the vehicle from tipping over. To effectively cope with such a situation, it is desirable that the vehicle be provided with support legs that prevent the vehicle from tipping over when the roll-over control is disabled. To effectively prevent the carrier from tipping over, the support legs are required to extend further away from the carrier body. However, if the support legs extend further away from the vehicle, the vehicle cannot travel in the limited space.

Disclosure of Invention

In view of such problems of the prior art, it is a primary object of the present invention to provide a vehicle provided with one or more support legs that can support the vehicle in a stable manner without unduly increasing the outer profile of the vehicle.

In order to achieve such an object, the present invention provides a carrier 1 comprising: a carrier main frame (body frame) 2; a traveling unit 3 provided on the vehicle main frame and configured to travel on a floor surface; a seat 4 vertically movably supported by the carrier main frame; a lifting unit 5 provided between the seat and the carrier main frame to move the seat between a high position and a low position; and support legs 71, 72 extending substantially downward from the seat and configured to be grounded when the seat is in the low position, wherein the support legs are movable between a retracted position positioned close to the carrier main frame and a deployed position positioned away from the carrier main frame, the support legs being configured to be in the retracted position when the seat is in the high position and to be moved from the retracted position to the deployed position when the seat is moved from the high position to the low position.

Thus, when the seat is in the raised position (which is typically the case when the vehicle is traveling), the outer profile of the vehicle can be minimized by placing the support legs in the retracted position. Thereby, the vehicle is enabled to travel in a relatively limited space. When the seat is in the low position, which is typically the case when the vehicle is stationary or parked, the stability of the vehicle is maximized by placing the support legs in the deployed position. Thereby, the carrier can be prevented from tipping over in a reliable manner.

Preferably, the support leg comprises: a first member 75 pivotally connected to the seat at an upper end thereof to be movable between a retracted position and a deployed position; a first ground member 76 provided at a lower end of the first member and configured to be grounded on the floor surface in a manner movable along the floor surface; and a first biasing member 77 urging the first member toward the retracted position, the first member being configured to move from the retracted position to the deployed position against a biasing force of the first biasing member by a reaction force applied to the first ground member from the floor surface.

Thus, when the first grounding member is grounded, the support leg can be deployed from the retracted position to the deployed position without any power actuator, so that the structure for deploying the support leg can be simplified.

Preferably, the support leg further comprises a first damper 83 disposed between the first member and the seat.

Thus, the impact on the seat and the vibration of the seat when the support leg is grounded can be reduced.

Preferably, the first member is positioned at the front of the vehicle and is provided with a footrest 79.

In this way, the footrest can be automatically moved away from the carrier or automatically into the use position when the first support leg is grounded.

Preferably, the first ground member is disposed directly below the footrest.

Thereby, the support surface of the footrest supporting the feet of the occupant can be positioned as low as possible, so that the sitting comfort of the occupant can be maximized.

Preferably, the support leg comprises: a second member 86 pivotally supported by the seat at an upper end thereof so as to be movable between a retracted position and a deployed position; a second ground member 87 provided at a lower end of the second member and configured to be grounded on the floor surface in a manner movable along the floor surface; a third member 88 pivotally supported by the intermediate portion of the second member at an upper end thereof and extending downward in a space defined between the carrier main frame and the second member; a third ground member 89 provided at a lower end thereof and configured to be grounded on the floor surface in a manner movable along the floor surface; and a second biasing member 91 that urges a lower portion of the third member downward away from the carrier frame.

Thus, when the second grounding member and the third grounding member are grounded, the support leg can be deployed from the retracted position to the deployed position without any power actuator, so that the structure for deploying the support leg can be simplified.

Preferably, the second grounding member includes a second roller rotatably supported by the second member, and the third grounding member includes a third roller having a larger diameter than the second roller and rotatably supported by the third member.

Since the third roller, which is grounded before the second roller, has a larger diameter than the second roller, the supporting leg can be grounded in a particularly stable manner.

Preferably, the support leg further includes a second damper 94 disposed between the third member and the seat.

Thus, the impact on the seat and the vibration of the seat when the support leg is grounded can be reduced.

Preferably, the traveling unit is provided with a driving wheel 8, which is driven under the inverted pendulum control.

Thus, the present invention provides a vehicle provided with one or more support legs that can support the vehicle in a stable manner without unduly increasing the outer profile of the vehicle.

Drawings

FIG. 1 is a front perspective view of a vehicle according to the present invention with the seat in a lowered position;

figure 2 is a rear perspective view of the vehicle with the seat in a lowered position;

FIG. 3 is a side view of the vehicle with the seat in a lowered position;

fig. 4 is a perspective view of the lifting unit;

fig. 5 is a sectional view of the lifting unit with the movable member in the reference position and the seat in the lowered position;

FIG. 6 is a cross-sectional view of the lift unit with the movable member in the reference position and the seat in the raised position;

FIG. 7 is a cross-sectional view of the lift unit with the movable member in the lowered position and the seat in the lowered position;

fig. 8 is a diagram showing a state of the engagement device when the movable member is at the lowered position;

fig. 9 is a diagram showing a state of the engagement device when the movable member is about to be raised from the lowered position; and

figure 10 is a left side view of the vehicle with the seat in the raised position.

Detailed Description

Preferred embodiments of the present invention as applied to a inverted pendulum carrier will be described below with reference to the accompanying drawings.

As shown in fig. 1 to 3, the carrier 1 is provided with: a carrier main frame 2; a traveling unit 3 that supports the carrier main frame 2 and causes the carrier main frame 2 to travel in any desired direction on the floor; a seat 4 supported by the vehicle main frame 2 and configured to seat a vehicle occupant; a lifting unit 5 provided between the carrier main frame 2 and the seat 4; and a control unit 6 that controls the traveling unit 3 and the lifting unit 5.

In this embodiment, the traveling unit 3 includes a pair of drive wheels 8 disposed on both sides of the vehicle main frame 2. For each of the pair of drive wheels 8, the traveling unit 3 further includes: a pair of drive disks 11 supported by the carrier main frame 2 to be driven individually and rotationally about a rotational center line extending laterally by respective motors (not shown in the drawings); and a plurality of driving rollers (not shown in the drawings) arranged on the respective driving disks 11 around the rotational center lines thereof so that the respective driving rollers can freely rotate around the inclined rotational center lines.

Each of the drive wheels 8 is provided with a plurality of follower rollers which are rotatably supported by the ring member 13 (like beads), and the drive roller is pressed against the follower rollers. With the rotation of the drive disk 11, the drive wheel 8 is frictionally driven by the engagement between the drive roller and the driven roller.

When both drive discs 11 are rotating in the same direction at the same rotational speed, the drive wheel 8 rotates in the same direction as the drive discs 11. When there is a difference in the rotational direction or rotational speed between the two drive disks 11, the driven roller 14 of the drive wheel 8 rotates relative to the ring member 13. As a result, the driving wheels 8 generate a lateral traction force to subject the vehicle to a lateral propulsive force. Thus, the vehicle 1 can travel in any desired direction. For details on the structure of the travelling unit 3, see US9,061,721B2 and other related prior patent publications.

The battery 16 is mounted on the rear end portion of the carrier main frame 22, and the control unit 6 is mounted on the inside or rear portion of the carrier main frame 2.

The lifting unit 5 is configured to raise and lower the seat 4 between the low position and the high position. The seat 4 includes: a seat frame (seat frame)18 supported by the lifting unit 5; and a cushion 19 placed on top of the seat frame 18. The occupant may sit on the cushion 19. The high position of seat 4 may be directly above the low position of seat 4. Alternatively, the high position of the seat 4 may be shifted to the lateral side or the front-rear side of the low position of the seat 4.

As shown in fig. 4 and 5, the lifting unit 5 includes a fixing base 21 fixedly attached to the carrier main frame 2. The fixed base 21 includes: a cross member 32 having a horizontally extending plate shape; and a pair of upright members 31 of the same shape extending vertically downward from the front and rear ends of the cross member 32, respectively. Each of the upright members 31 is provided with a shape of a letter U, and defines an opening 31A extending through the upright member 31 in the front-rear direction.

The lifting unit further comprises: a movable base 22 which is disposed in a vertically movable manner directly below the cross member 32 of the fixed base 21 (as will be discussed later); a pair of engagement devices 23 configured to selectively hold the movable base 22 at a predetermined reference position with respect to the fixed base 21; and an electric lift mechanism 24 configured to raise and lower the seat 4 with respect to the movable base 22. In this embodiment, the engaging means 23 is configured to selectively engage the front end and the rear end of the movable base 22 to the fixed base 21, respectively. The electric lift mechanism 24 is provided with: a seat base 26 provided above the fixed base 21 so as to be vertically movable with respect to the fixed base 21 and the movable base 22; an electric motor 27 mounted on the seat base 26 and having an output shaft 27A extending downward therefrom; a screw shaft 28 connected to the output shaft 27A via a coupling 38; and a nut 29 fixedly secured to the movable base 22 and threadedly connected with the screw shaft 28. The seat 4 is fixedly attached to the seat base 26. Thus, the screw shaft 28 extends vertically and passes through the movable base 22 via the nut 29.

The lower end of each upright member 31 is provided with a through hole extending in the front-rear direction, and is pivotably connected to an upwardly extending member of the carrier main frame 2 via a bolt pin 31B extending in the front-rear direction. Therefore, the fixing base 21 including the upright members 31 and the cross members 32 is held by a part of the carrier main frame 2 against forward and backward movement, but is pivotable about the bolt pin 31B. The lateral pivotal movement of the fixed base 21 is limited within a certain angular range by a stop (although not shown in the drawings). The fixed base 21 normally maintains the upright posture under the inverted pendulum control. The vehicle 1 may be propelled in the front-rear direction by the occupant leaning in the forward or rearward direction, and may be propelled in the lateral direction by the occupant leaning laterally in either direction.

The cross member 32 is provided with; a central opening 32A; and a pair of first sliding bushings 32B, one of which is located in front of the central opening 32A and the other of which is located behind the central opening 32A.

A pair of guide rods 34 extend vertically downward from the seat base 26 and each slidably pass through a corresponding first slide bushing 32B so that the seat base 26 can move vertically in a guided manner relative to the cross member 32 of the fixed base 21. Rubber cushions 36 may be provided on the lower surface of seat base 26 or the upper surface of cross member 32. In this embodiment, a rubber bumper 36 is provided at the upper end of the first slide bushing 32B, and the guide bar 34 passes through the rubber bumper 36. The lower limit position of the seat base 26 relative to the cross member 32 is defined by the lower surface of the seat base 26 abutting the rubber bumper pad 36.

The movable base 22 has a horizontally extending plate shape, and is provided with a pair of second slide bushes 22A, one of which is located in front of the nut 29 and the other of which is located behind the nut 29 so as to correspond to the first slide bush 32B. The guide rods 34 similarly pass through the second slide bushes 22A, respectively. The lower ends of the guide rods 34 are connected to each other by a lower member 37. As a result, the guide bar 34, the seat base 26, and the lower member 37 form a rectangular frame when viewed from the lateral direction. The lower end of the screw shaft 28 is connected to the lower member 37 in a freely rotatable but axially fixed manner. A pair of stoppers 40, one of which is in front of the screw shaft 28 and the other of which is behind the screw shaft 28, protrude upward from the upper surface of the lower member 37. As shown in fig. 6, the upper limit position of the lower member 37 and the seat base 26 with respect to the movable base 22 is defined by the upper end of the stopper 40 abutting against the lower surface of the movable base 22. Thus, the seat base 26 is vertically movable between a high position defined by the stopper 40 abutting the lower surface of the movable base 22 and corresponding to the high position of the seat 4, and a low position defined by the seat base 26 abutting the upper surface of the cross member 32 of the fixed base 21 and corresponding to the low position of the seat 4.

As shown in fig. 4 and 5, when the screw shaft 28 is rotated in the reverse direction by the motor 27 while the movable base 22 is held at the reference position, the seat base 26 is raised together with the motor 27 relative to the fixed base 21 by the engagement between the screw shaft 28 and the nut 29. The output shaft 27A of the motor 27, the screw shaft 28, and the guide bar 34 are arranged in parallel with each other. The electric motor 27 is integrated with a magnetic brake which is deactivated during operation of the electric motor 27 and which is activated when no current is supplied to the electric motor. Therefore, the electric motor 27 can provide the output torque when the electric current is supplied to the electric motor 27, but the output shaft 27A is prevented from rotating even under the external torque when the electric power is not supplied to the electric motor 27.

In this embodiment, the seat base 26 is connected to the seat frame 18 via a rubber cushion 39 to enhance the sitting comfort of the seat 4. The upper portion of the motor 27 is located inside the seat 4 for space utilization efficiency.

The nut 29 of the movable base 22 is preferably constituted by a ball screw having relatively small friction.

As shown in fig. 8 and 9, each engagement device 23 includes: a hook-like engagement member 41 displaceable in a substantially horizontal direction between an engagement position and a release position; a biasing member 42 that urges the engaging piece 41 toward the release position; and an electromagnet 43 (holding means) that holds the engaging piece 41 in the engaging position against the biasing force of the biasing member 42. The front engagement means 23 and the rear engagement means 23 are configured to be symmetrical to each other. To avoid redundancy, only the front engagement means 23 will be described below.

The base end or the shank portion of the hook joint 41 is rotatably supported by the front end portion of the fixed base 21 about a rotation center line extending in the horizontal direction. The engaging piece 41 is bent to face the convex side thereof in the front-rear direction.

The protruding piece 46 is provided at the base end of the engaging piece 41 and extends radially outward from the center of rotation of the engaging piece away from the shank of the hook engaging piece 41. The protruding piece 46 extends upward through a through hole 32C formed in the cross member 32, and protrudes above the cross member 32. An iron block 47 is attached to the front side of the protruding piece 46, and the electromagnet 43 is attached to the upper surface of the cross member 32 directly in front of the protruding piece 46. Therefore, the engaging piece 41 is rotatable between a first position (engaging position) in which the iron block 47 abuts the electromagnet 43 and a second position (releasing position) in which the iron block 47 is spaced apart from the electromagnet 43. When the engaging piece 41 is in the first position, the electromagnet 43 may detachably hold the iron block 47 thereto.

The engagement member 41 is provided with a leg 49 that branches off from the shank portion of the hook-like engagement member 41. The legs 49 extend rearwardly from the handle portion of the engaging member 41 to form an extended mouth in cooperation with the tip end of the engaging member 41. In particular, legs 49 extend generally parallel to the tip of engaging member 41 so as to define a space between legs 49 and the tip of engaging member 41. Thus, when the hook portion is in the release position, the arm 49 extends to a point displaced upward from the tip end of the engaging piece 41 and overlapping the movable base portion. In particular, the arms 49 extend beyond a line connecting the centerline of rotation of the engagement member 41 and the tip end of the engagement member 41, at least when the engagement member is in the disengaged position.

A roller 51 is rotatably provided at the tip end of the engaging piece 41, and another roller 50 is provided at the free end of the arm 49. The rotational center lines of these rollers 50, 51 extend parallel to the rotational center line of the engaging member 41.

The engaging piece 41 is urged towards the release position by a biasing member 42. In this embodiment, the biasing member 42 is constituted by a torsion coil spring that passes around a pivot pin of the engaging piece 41 to act between the fixed base 21 and the engaging piece 41. The electromagnet 43 is configured to hold the engaging piece 41 in the engaging position by attracting the iron block 47 of the engaging piece 41.

As shown in fig. 8, when engagement member 41 is in the release position, engagement member 41 and leg 49 are inclined downwardly toward the tip side. In the release position, when viewed from above, arm 49 overlaps movable base 22, and engagement member 41 does not overlap movable base 22. In other words, when the engaging piece 41 is in the release position, the engaging piece 41 is disengaged from the movable base 22. At this time, the iron block 47 is positioned away from the electromagnet 43. A stopper 52, preferably made of a soft material such as rubber, is attached to the front side of the shank of the joint 41. In the release position, the stop 52 contacts the lower surface of the cross member 32. In other words, the release position of the engaging piece 41 is defined by abutting the stopper 52 onto the lower surface of the cross member 32.

When engagement member 41 is in the engaged position, as shown in fig. 9, the tip of engagement member 41 and arm 49 are both oriented generally horizontally. In the engaged position, both the arm 49 and the engaging member 41 overlap the movable base 22 when viewed from above. In other words, when the engaging member 41 is in the engaging position, the engaging member 41 may engage the movable base 22 to prevent downward movement. When the engaging member 41 is in the engaging position, the rotation center line of the roller 51 at the tip end of the engaging member 41 may be located directly below the rotation center line of the engaging member 41. When the engaging piece 41 is in the engaging position, the iron block 47 is in contact with the electromagnet 43 and held by the electromagnet 43.

When current is supplied to the electromagnet 43, the electromagnet 43 attracts the iron block 47 to hold the engaging piece 41 in the engaging position against the spring force of the biasing member 42. When the supply of the current to the electromagnet 43 is terminated, the engaging piece 41 is moved to the release position by the biasing force of the biasing member 42.

As shown in fig. 9, the movable base 22 can be held at the reference position by engagement by the engagement means 23. When the movable base 22 is at the reference position and the engaging piece 41 is in the engaged state, the movable base 22 is held at the reference position via the roller 51 by the tip end of the engaging piece 41. At this time, the tip end of the engaging piece 41 is located directly below the movable base 22, and abuts against the lower surface of the movable base 22 via the roller 51. At this time, a gap is formed between the upper surface of the movable base 22 and the roller 50 at the tip end of the arm 49. In this way, once engaged, the engagement piece 41 engages the movable base 22 to prevent vertical movement and holds the movable base 22 in the aforementioned reference position. The contact area between each engaging piece 41 and the movable base 22 is located directly below the rotation center line of the engaging piece 41.

The operation mode of the vehicle 1 is described below. The control unit 6 controls the operation of the electromagnet 43 and the motor 27 of the engaging device 23 so that the lifting unit 5 can raise and lower the seat 4 as needed.

Fig. 5 shows an initial state in which the movable base 22 is held at the reference position and the seat 4 is at the low position. This is a typical situation when the vehicle 1 is parked. When the vehicle occupant sits on seat 4, control unit 6 raises seat 4 to the high position by rotating motor 27 in the reverse direction. Thereby, the vehicle occupant can view the surrounding environment from a high viewing angle. Figure 6 shows the seat 4 in the raised position.

When the vehicle occupant wishes to get off the vehicle 1, the control unit 6 lowers the seat 4 to the low position by rotating the motor 27 in the forward direction. Thereby, the vehicle occupant can easily get off the seat 4.

When the vehicle 1 is traveling with the seat 4 in the raised position as shown in fig. 5, an emergency situation may occur in which the vehicle 1 may not be able to maintain the upright position or else the vehicle occupant is required to descend from the seat as quickly as possible. In such a situation, it is desirable to lower the seat 4 as quickly as possible. Otherwise, it becomes inconvenient to require the vehicle occupant to descend from the vehicle 1 from a relatively high position.

In such a case, when an emergency is detected, the control unit 6 stops supplying power to the electromagnet 43 to move the engaging piece 41 from the engaging position to the releasing position by the biasing force of the biasing member 42. As a result, the movable base 22 descends together with the seat 4 by gravity. Since this is a free fall, the lowering of the seat 4 occurs very quickly, without any external power supply.

At this time, the seat base 26 and the lower member 37 (connected to each other by the guide bar 34 and the screw shaft 28) are also lowered together with the movable base 22 (connected to the seat base 26 via the screw shaft 28 and the nut 29). The movable base 22 descends until the seat base 26 contacts the cross member 32 via the rubber cushion 36. Fig. 7 shows this state. As a result, the seat 4 is placed at the lowest position in the vertical movement range. The lowering speed of the movable base 22 can be adjusted by adjusting the friction between the first slide bush 32B and the guide bar 34.

The seat 4 can be raised from this lowest position in the following manner. With the engagement device 23 in the release position, the motor 27 is rotated in the positive direction, with the result that the movable base 22 is raised due to the fit between the screw shaft 28 and the nut 29.

As the motor 27 rotates in the positive direction to raise the movable base 22 toward the reference position, the upper surface of the movable base 22 eventually pushes the arm 49 upward against the spring force of the biasing member 42, thereby displacing the engaging member 41 from the release position to the engaging position. As a result, the tip end of the engaging piece 41 is located below the movable base 22. Once the engaging piece 41 reaches the engaging position, the iron blocks 47 contact the corresponding electromagnet 43, and the rotation of the engaging piece 41 is terminated. As a result, the movement of the movable base 22 is restricted by the arm 49, and the load applied to the motor 27 increases. Then, the control unit 6 stops the forward rotation of the motor 27 based on such an increase in load. At the same time, the control unit 6 supplies current to the electromagnets 43 so that the iron blocks 47 remain attached to the respective electromagnets 43. As a result, the engaging piece 41 and the iron block 47 are held in the engaging position. Alternatively, the control unit 6 may start supplying the current to the electromagnet 43 before the engaging piece 41 reaches the engaging position.

After stopping the forward rotation of the motor 27, the control unit 6 reverses the rotation of the motor 27. As a result, the movable base 22 starts to move downward with respect to the seat base 26 and the fixed base 21, as shown in fig. 9. At this time, the load applied to the motor 27 during the time when the movable base 22 moves downward between the arm 49 and the engaging member 41 is relatively small. Once the lower surface of the movable base 22 comes into contact with the engaging member 41, the load on the motor 27 starts to increase as the downward movement of the movable base 22 is resisted by the engaging member 41. Therefore, the control unit 6 can determine that the movable base 22 has reached the reference position by detecting an increase in the load of the motor 27.

In this way, once movable base 22 reaches the reference position, control unit 6 can raise seat base 26 and seat 4 relative to movable base 22 and fixed base 21 by reversing the rotation of motor 27.

The vehicle 1 has at least one support leg to keep the vehicle 1 in an upright position even in the event of the inverted pendulum control being closed. In this embodiment, as shown in fig. 1 to 3 and 10, the vehicle 1 has three support legs 71 and 72, and these three support legs 71 and 72 extend downward from the seat 4 and contact the floor surface when the seat 4 is in the low position. These three support legs 71 and 72 are composed of one front support leg 71 centrally located at the front end of the carrier 1 and a pair of rear support legs 72 located on both sides of the rear portion of the carrier 1. The support legs 71 and 72 are each pivotally supported at their upper end to be movable between a retracted position in which the support legs are pivoted towards the carrier 1 and an extended position in which the support legs are pivoted away from the carrier 1. In this embodiment, the front support leg 71 is configured to pivot forward when moving from the retracted position to the deployed position, and the rear support leg 72 is configured to pivot rearward when moving from the retracted position to the deployed position. When the seat 4 is moved from the high position to the low position, the support legs 71 and 72 are moved from the retracted position to the deployed position, and are grounded at the lower ends of the support legs 71 and 72.

As shown in fig. 1, the seat 4 is provided with a front support 74 that extends forward and then downward centrally from the front end of the seat frame 18, and front support legs 71 extend downward from the lower end of the front support 74. At least one reinforcement member may be connected between the lower end of the front support 74 and the seat frame 18. The front support 74 may be formed as part of the seat frame 18. The front support leg 71 includes: a first member 75 connected to the front support 74 at an upper end thereof so as to be pivotable about a laterally extending center of rotation; a plurality of first rollers 76 (first ground members) provided at the lower end of the first member 75; and a first biasing device 77 provided between the first member 75 and the front support 74 to urge the first member 75 toward a position corresponding to the retracted position.

The lower end of the first member 75 is provided with a footrest 79 formed as a shelf extending laterally over substantially the entire width of the vehicle and projecting forwardly to support the feet of the occupant. Thus, in this embodiment, the footrest 79 has an L-shaped cross section when viewed from the lateral direction. The footrest 79 is provided with a trunnion seat 81 projecting forward at a lower end of the footrest to pivotably support a lower end of the first biasing means 77. The upper end of the first biasing device 77 is pivotally connected to a vertically intermediate portion of the front support 74.

The first member 75 can be pivoted between a retracted position in which the first member 75 hangs substantially vertically from the front support 74 (as shown in fig. 10) and a deployed position in which the first member 75 is raised forward at an angle (10 degrees to 45 degrees) from the retracted position. A stopper 82 is provided at a lower end portion of the front support 74 to define a limit at which the first member 75 pivots rearward in the retracted position. The stopper 82 may be provided with a buffer member such as rubber. By swinging the first member 75 from the retracted position to the deployed position, the lower end of the first member 75 moves forward away from the carrier main frame 2 or substantially in the horizontal direction.

The first roller 76 is supported by a footrest 79. In this embodiment, the first roller 76 includes four rollers arranged laterally at regular intervals just below the footrest. The diameters of the outer two of the first rollers 76 may be slightly larger than the diameters of the inner two of the first rollers 76. The first roller 76 may consist of a simple roller, a caster roller, or a ball roller having a transversely extending center line of rotation. The number of first rollers 76 may be other than four, but less or more than four, and possibly even one.

The first biasing means 77 may comprise a linearly extendable cylinder which is normally biased in the direction of extension. The first biasing means 77 may consist of a gas spring or a spring-loaded means. The first biasing means 77 may further comprise a torsion spring provided at a junction point between the front support 74 and the first member 75.

As shown in fig. 10, the first member 75 is urged toward the retracted position by the first biasing means 77 without any external force. As shown in fig. 1 to 3, when the lower end of the first member 75 is pushed upward by the reaction force received from the floor surface via the first roller 76, the first member 75 swings upward from the retracted position to the deployed position against the biasing force of the first biasing device 77. Specifically, the lower end of the first member 75 is moved forward along the floor surface, and the front support leg 71 is placed in the deployed position. In other words, when the lower end of the first member 75 is pushed up by the floor surface via the first roller 76 in response to lowering of the seat 4, the first member 75 is pushed up by the floor surface via the first roller 76, and is pivoted to a position corresponding to the deployed position.

The front support leg 71 may be provided with a first damper 83 positioned between the first member 75 and the front support 74 (or the seat 4) to damp movement of the first member 75 relative to the seat 4. The first damper 83 may be composed of a fluid damper having a cylinder in which fluid is enclosed, a piston movable relative to the cylinder, and a rod connected to the piston. The first damper 83 may be integrally formed with the first biasing device 77. If the first biasing means 77 is composed of a gas spring, the gas spring may also serve as the first damper 83. In other embodiments, the first damper 83 may include a rotary damper provided at a joint between the front support 74 and the first member 75.

As shown in fig. 1 and 2, a rear support leg 72 extends downward from either lateral outer portion of the rear portion of the seat 4. The seat 4 is provided with a pair of rear stays 85 projecting downward from either side end of the rear end of the seat frame 18. The rear support 85 may be formed as part of the seat frame 18. The rear support legs 72 are provided with the same configuration and are supported by corresponding rear supports 85. In the following description, in order to avoid redundancy, only one of the rear support legs 72 is described.

Each rear support leg 72 includes: a second member 86 pivotably connected to the seat 4 at an upper end thereof; a second roller 87 (second ground member) provided at a lower end of the second member 86 and configured to contact the floor surface; a third member 88 pivotally connected to an intermediate portion of the second member 86 at an upper end thereof; a third roller 89 (third ground contact member) provided at a lower end of the third member 88 and configured to contact the floor surface; and a second biasing means 91 provided between the lower end portion of the third member 88 and the seat 4 to urge the third member 88 in the downward and rearward direction to urge the second member 86 to a position corresponding to the retracted position. The third member 88 is disposed relative to the second member 86 such that the third member 88 is located in front of the second roller 87 or extends in a space defined between the carrier main frame 2 and the second member 86.

As shown in fig. 3 and 10, the upper end of the second member 86 is connected to the rear support 85 so as to be pivotable about a laterally extending rotation center line between a retracted position in which the second member 86 is suspended substantially vertically from the rear support 85 and a deployed position in which the second member 86 is tilted rearward relative to the rear support 85 about the rotation center line of the second member. A stop 93 is provided on the rear support 85 to limit rearward pivotal movement of the second member 86 to the deployed position. The stopper 93 may be provided with a buffer member such as rubber. As the second member 86 swings from the retracted position to the deployed position, the lower end of the second member 86 moves away from the carrier main frame 2 or moves rearward substantially in the horizontal direction. The second roller 87 is supported at the lower end of the second member 86 so as to be rotatable about a rotation center line extending in the lateral direction. The second roller 87 may be any member movably grounded to the floor surface, and may be replaced by a ball or a sled (slid), for example.

The second biasing means 91 may comprise a linearly extendable and retractable cylinder and is normally urged in the direction of extension.

The second biasing means 91 may be a gas spring or a spring-loaded cylinder. The second biasing device 91 has: an upper end pivotably connected to the corresponding rear support 85; and a lower end pivotably connected to a front lower end of the third member 88. The upper end of the second biasing means 91 is positioned a distance forward of the upper end of the second member 86. As a result, the rear support 85, the second member 86, the third member 88, and the second biasing device 91 form a four-bar linkage that can extend and retract the second biasing device 91.

As shown in fig. 10, when no load is applied to the second roller 87 or the third roller 89 is spaced apart from the floor surface, the second biasing device 91 is fully extended such that the second member 86 is suspended substantially vertically from the rear support 85 and the third member 88 is also suspended substantially vertically from the second member 86. Thus, the four-bar linkage is in a substantially collapsed state. In other words, the angle between the third member 88 and the second biasing device 91 is minimized, and the angle between the second member 86 and the third member 88 is maximized. In the retracted position, the second member 86 is placed in a forward position, i.e., a position close to the carrier main frame 2. In this way, the second member 86 is urged toward the retracted position by the second biasing means 91, and thereby the rear support leg 72 is placed in the retracted position.

In the retracted position of the rear support leg 72, the third roller 89 is located below the second roller 87. The diameter of the third roller 89 is larger than the diameter of the second roller 87. The third roller 89 may be any other component that may be grounded in a horizontally movable manner, such as a ball or a sled.

As shown in fig. 3 and 10, when the third member 88 is pushed against the floor surface via the third roller 89 due to lowering of the seat 4, the third member 88 pivots forward. At the same time, the second member 86 is pushed by the third member 88 to swing rearward to a position corresponding to the deployed position of the rear support leg 72, thereby grounding the second roller 87. More specifically, when the lower end of the third member 88 is pushed upward by the floor surface via the third roller 89, the second biasing device 91 is retracted, and the upper end of the third member 88 is moved rearward. This pivots the second member 86 rearward relative to the rear support 85 to move the lower end of the second member 86 rearward. As a result, the distance between the lower end of the second member 86 and the lower end of the third member 88 increases, and the distance between the lower end of the second member 86 and the carrier main frame 2 is the same. At this time, the lower end of the second member 86 rests on the floor via the second roller 87, and the lower end of the third member 88 rests on the floor via the third roller 89. In this manner, the second member 86 is moved rearwardly until the rear support leg 72 is disposed in the deployed position.

The rear support leg 72 is provided with a second damper 94 connected between the second member 86 and the seat 4 to damp oscillatory and impulsive movements of the second member 86 relative to the seat 4. The second damper 94 may be a fluid damper including a cylinder having fluid enclosed therein, a piston movable relative to the cylinder, and a rod connected to the piston. The second damper 94 may be formed as an integral part of the second biasing device 91. As described above, if the second biasing device 91 is a gas spring, the gas spring may also be used as the second damper 94. In the present embodiment, the second damper 94 is formed integrally with the second biasing device 91, and is connected to the rear support 85 at one end thereof, and is connected to the third member 88 at the other end thereof. Alternatively, the second damper 94 may be composed of a rotary damper provided at a joint between the rear support 85 and the second member 86 or a joint between the second member 86 and the third member 88. Similarly, the second biasing means 91 may consist of a torsion spring provided at the junction between the rear support 85 and the second member 86 or at the junction between the second member 86 and the third member 88.

As shown in fig. 10, when the seat 4 is in the high position, the front support leg 71 is raised from the floor surface and is placed in the retracted position by the biasing force of the first biasing device 77. Likewise, the rear support leg 72 is raised from the floor and placed in the retracted position under the spring force of the second biasing means 91.

When the seat 4 is lowered to the low position, the front support leg 71 is pushed by the reaction force received from the floor surface via the first roller 76, and thus, transitions from the retracted position to the deployed position against the biasing force of the first biasing device 77. The rear support leg 72 is also urged by the reaction force received from the floor surface via the third roller 89 and, therefore, transitions from the retracted position to the deployed position against the biasing force of the second biasing means 91. At this time, the movement of the front support leg 71 is damped by the first damper 83, and the movement of the rear support leg 72 is damped by the second damper 94 so as to damp the downward movement of the seat 4.

In the deployed position of the front support legs 71, the first rollers 76 that are in contact with the floor surface are positioned farther away from the carrier main frame 2 than in the retracted position, thereby improving the stability of the carrier 1. Similarly, in the deployed position of the rear support leg 72, the second roller 87, which is in contact with the floor surface, is positioned farther away from the carrier main frame 2 than in the retracted position, thereby improving the stability of the carrier 1.

In the present embodiment, when it is necessary to lower the seat 4 as quickly as possible, the control unit 6 stops supplying the current to the electromagnet 43. As a result, the iron block 47 is separated from the electromagnet 43 by the biasing force of the biasing member 42 to move the roller 51 of the engaging piece 41 away from the lower surface of the movable base 22. As a result, the movable base 22 can be moved downward relative to the fixed base 21 by gravity to place the seat 4 in the low position. Since the downward movement of the movable base 22 together with the seat base 26 occurs as a free fall, the seat 4 can be quickly lowered to meet the needs in an emergency. When the rubber cushion 39 abuts against the lower surface of the seat base 26, the downward movement of the movable base 22 is terminated. The impact at this time is absorbed by the deformation of the rubber bumper 39.

In the present embodiment, since the seat 4 can be lowered without involving the electric lifter mechanism 24, the lowering of the seat 4 in an emergency can be performed in a quick and reliable manner. Since the displacement direction of the engaging piece 41 and the displacement direction of the movable base 22 are orthogonal to each other, the electromagnet 43 is enabled to maintain the engaging piece 41 in the engaged state with relatively small power. In other words, the power requirements of the electromagnet 43 can be reduced. Moreover, since the load of the movable base 22 is applied to the tip end of the engaging piece 41 in the radial direction with respect to the rotation center line of the engaging piece 41, the force to be generated by the electromagnet 43 to hold the iron block 47 in the engaged state can be reduced. As a result, power consumption of the electromagnet 43 can be minimized.

When it is desired to return the seat 4 to the high position, the motor 27 is rotated in the positive direction, and the supply of current to the electromagnet 43 is restarted. Due to the threaded connection of the screw shaft 28 and the nut 29, the movable base 22 is raised upward until the movable base 22 abuts the rollers 50 of the arm 49. As the movable base 22 is further raised, the engaging pieces 41 pivot in such a manner that the iron blocks 47 are brought into contact with the corresponding electromagnets 43. As a result, the roller 51 of the engaging member 41 is placed in an overlapping relationship with the movable base 22. Therefore, the engaging piece 41 is returned to the engaging position, whereby the movable base 22 is firmly engaged to the fixed base 21. During this process, seat 4 remains in the lowered position.

If the control unit 6 then activates the motor 27 in the reverse direction, the seat base 26 is raised together with the seat 4 relative to the vehicle main frame 2 until the stopper 40 provided on the lower member 37 abuts against the lower surface of the movable base 22, since the movable base 22 is firmly engaged to the fixed base 21. As a result, the seat 4 assumes the high position.

When it is desired to lower the seat 4 slowly or gradually from the high position, the motor 27 is rotated in the positive direction, so that the seat base 26 can be lowered together with the seat 4 by means of the engagement between the screw shaft 28 and the nut 29 until the lower surface of the seat base 26 abuts against the rubber cushion 36. Accordingly, the lifting unit 5 transits from the state shown in fig. 6 to the state shown in fig. 5.

In the present embodiment, when seat 4 is in the high position, support legs 71 and 72 are both in the retracted position, thereby preventing the support legs from protruding from the outer contour of vehicle 1 and enabling vehicle 1 to travel in a limited space. When seat 4 is in the lowered position, support legs 71 and 72 are both in the deployed position, so that stability of vehicle 1 on the floor surface can be maximized. Since the support legs 71 and 72 are changed from the retracted position to the deployed position by the contact with the floor surface, no driving means is required for such change. Therefore, the structure of the support legs 71 and 72 can be simplified and miniaturized.

Since the support legs 71 and 72 are equipped with the dampers 83 and 94, it is possible to reduce the impact on the occupant seated on the seat 4 when the support legs 71 and 72 are displaced from the retracted position to the deployed position by contact with the floor surface.

A footrest 79 is provided on the first member 75 to be displaceable together with the first member 75 between a retracted position and a deployed position. Therefore, when the front support leg 71 is in the deployed position, the footrest 79 is appropriately moved forward for the convenience of the occupant. In addition, since the footrest 79 is grounded via the first roller 76 at the deployed position of the front support leg 71, the sole of the occupant is positioned near the floor surface so that the occupant can stabilize his or her posture in a comfortable manner.

The rear support legs 72 are each provided with a second member 86 and a third member 88 which diverge from each other, and are grounded at a second roller 87 provided at a lower end of the second member and a third roller 89 provided at a lower end of the third member, respectively. Therefore, the rear support leg 72 can support the vehicle 1 on the floor surface in a stable manner. In addition, since the third roller 89 contacts the floor surface before the second roller 87 contacts the floor surface, and the diameter of the third roller 89 is larger than that of the second roller 87, the rear support leg 72 can contact the floor surface with good stability.

The present invention has been described in terms of specific embodiments, but is not limited by such embodiments, and may be modified in various ways without departing from the scope of the invention.

The number of support legs 71 and 72 is not limited to three and other arrangements are possible without departing from the scope of the invention. For example, there may be only one leg in front or at the back; there may be two legs, one at the front of the carrier and the other at the rear of the carrier; and so on.

The first, second and third rollers 76, 87, 89 may be replaced with other components that may be grounded on and movable along the floor surface. The first, second, and third rollers 76, 87, 89 may also be balls rotatably disposed in the footrest 79, second and third members 86, 88, or fixed to these members to act as curved surfaces of the footrest.