Seat reclining apparatus

1. A seat reclining apparatus comprising:

a base plate, an outer side of which faces one of a seat cushion side frame and a seatback side frame;

a ratchet plate which includes an internal gear, said ratchet plate being fixed to the other of said seat cushion side frame and said seatback side frame so as to face said base plate while being rotatable relative thereto;

a lock member supported on a surface of said base plate which faces said ratchet plate so that said lock member is movable between an engaged position in which an outer toothed portion formed on an outer peripheral surface of said lock member is engaged with said internal gear of said ratchet plate and a disengaged position in which said outer toothed portion is disengaged from said internal gear of said ratchet plate toward an inner peripheral side;

a rotational cam which is positioned between said base plate and said ratchet plate and rotates relative to said base plate and said ratchet plate in association with an operation of an operating member between a locked position to position said lock member in said engaged position and an unlocked position to position said lock member in said disengaged position;

a welding protrusion which protrudes from said outer side of said base plate and is engaged with a holding portion, which is formed as one of a through-hole and a bottomed hole in said one of said seat cushion side frame and said seatback side frame; and

a protrusion-corresponding recess formed in said surface of said base plate at a position corresponding to a position of said welding protrusion, and which faces said ratchet plate,

wherein said outer toothed portion of said lock member, at said engaged position, is positioned radially inside an outer peripheral surface of said protrusion-corresponding recess, wherein said outer peripheral surface is closest to the periphery of said base plate,

wherein said welding protrusion includes a welding portion, at an outer edge of said welding protrusion, which is offset from said outer toothed portion so as to be positioned radially closer to an outer peripheral edge of said base plate than said outer toothed portion of said lock member in said engaged position, and

wherein a weld is applied so as to extend over said welding portion and an outer edge of said holding portion.

2. The seat reclining apparatus according to claim 1 , wherein said base plate is a press-molded product, and

wherein said lock member and said protrusion-corresponding recess are positioned to face each other.

3. The seat reclining apparatus according to claim 1 , wherein said welding protrusion comprises a pair of side end surfaces which are flat and spaced from each other in a rotational direction of said ratchet plate relative to said base plate, and

wherein said holding portion includes a pair of flat portions which face said pair of side end surfaces of said welding protrusion, respectively.

4. The seat reclining apparatus according to claim 1 , wherein said welding portion is offset to prevent deformation of said base plate into said lock member at said weld.

5. The seat reclining apparatus according to claim 1 , further comprising a wedge to press said locking member into a locking direction in said engaged position.

6. The seat reclining apparatus according to claim 5 , wherein said wedge includes a pressing portion to contact a pressed portion of said locking member.

7. The seat reclining apparatus according to claim 5 , wherein said locking member includes a wedge-engaging groove to receive said wedge.

8. The seat reclining apparatus according to claim 1 , wherein said internal gear of said ratchet plate is positioned at said inside of said outer peripheral surface of said protrusion-corresponding recess, and

wherein said outer peripheral surface is closest to the periphery of said base plate.