22. That is to say, the slider 38 is capable of reciprocal movement (sliding) in the front-rear direction along the slot 26.

Also, the drive mechanism 30 has a drive rod 37, of which one end portion 37A (which can be regarded as an example of a first end portion in the present disclosure) is attached to a peripheral edge portion 36A of the gear 36, and other end portion 37B (which can be regarded as an example of a second end portion in the present disclosure) is attached to a rear end portion 38A of the slider 38. A slot 28 of a predetermined size (length) curved in a substantially arcuate shape in plan view is formed in a portion of the support plate 24 that faces a path of turning of the peripheral edge portion 36A of the gear 36 in the up-down direction.

A pin 35, which is cylindrical, can be inserted through this slot 28, a lower end portion of this pin 35 is attached to the peripheral edge portion 36A of the gear 36, and an upper end portion of this pin 35 is attached to the one end portion 37A of the drive rod 37. That is to say, the peripheral edge portion 36A of the gear 36 and the one end portion 37A of the drive rod 37 are turnably coupled by the pin 35 inserted through the slot 28. Thus, the one end portion 37A of the drive rod 37 and the peripheral edge portion 36A (the pin 35) of the gear 36 are configured to be capable of moving along the slot 28.

In side view, the slider 38 has a shape including a portion that protrudes upward at the middle portion in the front-rear direction, and the rear end portion 38A extending toward the rearward side is turnably coupled to the other end portion 37B of the drive rod 37 by a pin 39. At a middle portion in the axial direction of a slide shaft 40 that is cylindrical, of which the axial direction is the right-left direction, is attached to the middle portion of the slider 38 in the front-rear direction thereof.

According to the drive mechanism 30 configured as described above (specifically, the mechanism in which the gear 36 is turned in both forward and reverse directions via the drive gear, by the rotational driving of the drive motor 34 controlled by the control device 32, and the slider 38 moves in the front-rear direction via the drive rod 37), the slide shaft 40 is capable of reciprocally moving (sliding) in the advancing direction and the backward direction of the wheelchair 60.

Both right and left sides of the base member 22 are formed as the side wall portions 22S of a predetermined height that are bent upward and thus erected. The lock arms 42 are respectively provided overlapping on outer sides of the side wall portions 22S so as to be turnable in the up-down direction. Each of the right and left lock arms 42 is formed in a flat plate shape of which the front-rear direction is the longitudinal direction, and a basal portion 44 disposed at a front end portion of the base member 22 is turnably attached to a front end portion of the side wall portion 22S of the base member 22 by a shaft portion 45 of which the axial direction is the right-left direction.

A torsion spring (omitted from illustration), serving as an example of a biasing member, is provided on each shaft portion 45 that is turnably supports each basal portion 44, such that the distal end portion (end portion toward the backward direction side of the wheelchair 60) 46 side of each lock arm 42 disposed on a rear portion side of the base member 22 is always biased upward. That is to say, one end portion of the torsion spring is retained by the lock arm 42 and the other end of the torsion spring is retained by the base member 22.

The side wall portions 22S of the base member 22 are each formed with a slot 22B, of which the front-rear direction is the longitudinal direction, through which both end portions of the slide shaft 40 in the axial direction are respectively inserted, and a cam hole portion 48 into which both of the end portions of the slide shaft 40 in the axial direction are respectively inserted is formed partway along each lock arm 42 in the longitudinal direction thereof. Each cam hole portion 48 is formed in a predetermined cam shape of which the longitudinal direction is the front-rear direction. A substantially arcuate notch portion 46A, into which the fixing bar 68 of the wheelchair 60 is fitted (retaining the fixing bar 68), is formed on a lower side of the distal end portion 46 of each lock arm 42.

As illustrated in FIG. 6, each lock arm 42 that is configured as described above has a configuration in which each distal end portion 46 turns from the upward side to the downward side against biasing force by the torsion spring, by the slide shaft 40 moving rearward (in the backward direction of the wheelchair 60), thereby pinning down the fixing bar 68 provided on the wheelchair 60. That is to say, the notch portion 46A of each lock arm 42 is configured to be fitted to the fixing bar 68 of the wheelchair 60, such that each lock arm 42 locks the wheelchair 60 so as not to move.

In this configuration, as the slide shaft 40 moves toward the forward side (in the advancing direction of the wheelchair 60), the distal end portion 46 of each lock arm 42 turns from the downward side to the upward side under the biasing force (returning force) of the torsion spring, and the pinning down of the fixing bar 68 of the wheelchair 60 is released. That is to say, the notch portion 46A of each lock arm 42 is configured to be removed from the fixing bar 68, such that each lock arm 42 unlocks the wheelchair 60 so as to capable of moving.

As viewed from the axial direction of the slide shaft 40, an upper face of the distal end portion 46 of each lock arm 42 has an inclined face 46B that is at a predetermined angle θ (see FIGS. 4 to 6), over which a lower face of a footrest 66 of the advancing (moving in the forward direction) wheelchair 60 can come into sliding contact. This is because the footrests 66 of the wheelchair 60 are also inclined toward an obliquely forward and upward side at a predetermined angle with respect to a lateral direction, as illustrated in FIG. 9.

That is to say, as illustrated in FIG. 7B, the inclined face 46B of each lock arm 42 is arranged to be pressed by the lower face of the footrest 66 from the upward side, and to be capable of turning toward the downward side while in sliding contact relative to the footrest 66, without being caught on the lower face of the footrest 66 of the wheelchair 60 that is advancing, and hindering the wheelchair 60 from boarding.

Accordingly, the angle θ at the distal end portion 46 of each lock arm 42 is set in accordance with the inclination angle of the footrest 66 of the wheelchair 60, and is generally 35 degrees to 45 degrees or 38 degrees to 42 degrees, and is 40 degrees in the present embodiment. Also, each lock arm