Seat apparatus and seat adjustment mechanism for the same

A seat apparatus for a vehicle, including a seat cushion and a seat back having first and second seat members rotatably connected to each other, comprising:

• a side frame mechanism serving as one of the first and second seat members, a lower end of which is tiltably connected to a rear end of a seat cushion frame arranged within the seat cushion;
• an upper cross-member serving as the other of the first and second seat members arranged at an upper portion of the side frame mechanism;
• and
• a seat adjustment mechanism adjusting an angle formed between the side frame mechanism and the upper cross-member rotatably connected to each other and including:
• a first link member adapted to be connected to the first seat member and including a first end rotatably supported by the first seat member;
• a second link member adapted to be rotatably connected to the second seat member and including a first end rotatably supported by the second seat member and a second end rotatably connected to the first link member;
• a drive device;
• and
• an extending and retracting device driven by the drive device and extending and retracting linearly,
• wherein one of the drive device and the extending and retracting device is rotatably connected to a second end of the first link member and the other of the drive device and the extending and retracting device is rotatably connected to the second seat member,
• wherein assuming that
• a connecting point between the first link member and the second link member is defined as a connecting point P,
• a connecting point between the first seat member and the first link member is defined as a connecting point Q,
• a connecting point between the second seat member and the second link member is defined as a connecting point R,
• a connecting point between the first link member and one of the drive device and the extending and retracting device is defined as a connecting point S,
• a connecting point between the second seat member and the other of the drive device and the extending and retracting device is defined as a connecting point T,
• a line linearly passing through the connecting points Q and R is defined as a line L1, and
• a line linearly passing through the connecting points S and T is defined as a line L2,
• the first and second link members, the first link member and one of the drive device and the extending and retracting device, and the second link member and the other of the drive device and the extending and retracting device are connected to each other so that a ratio a/b of a distance “a” from the connecting point P to the line L1 relative to a distance “b” from the connecting point P to the line L2 is set to be less than one,
• wherein the drive device is driven to linearly move the extending and retracting device to rotate the first link member relative to the second link member to thereby generate a relative rotation between the first seat member and the second seat member in order to adjust the angle between the first and second seat members, and
• wherein the connecting point Q and the connecting point S are adapted to be fixed respectively at rear and front portions of the side frame mechanism in an inner side thereof and the upper cross-member is connected to the side frame mechanism and driven to be tiltable forward relative to the side frame mechanism.