Acceleration device for vehicle

An acceleration device for an automotive vehicle comprising:

• a supporting body to be fixed to a vehicle body;
• a pedal shaft rotatably supported by the supporting body;
• a rotating member provided at a radial-outer side of the pedal shaft and rotatable in accordance with rotation of the pedal shaft;
• a biasing member for biasing the rotating member in a pedal closing direction;
• an acceleration pedal to be operated by a vehicle driver;
• a pedal arm connected at its one end to the acceleration pedal and converting a stepping movement of the acceleration pedal by the vehicle driver into a rotational torque of the pedal shaft;
• and
• a rotational angle detecting unit for detecting a rotational angle of the pedal shaft with respect to the supporting body,
• wherein the rotating member comprises;
• a boss portion formed at the radial-outer side of the pedal shaft;
• a biasing-member holding portion extending from the boss portion in a radial-outward direction of the pedal shaft for holding one end of the biasing member;
• and
• a mechanically-weaker portion formed between the boss portion and the biasing-member holding portion, wherein
• the boss portion, the biasing-member holding portion and the mechanically-weaker portion are integrally formed as one unit;
• the biasing-member holding portion is configured to be broken away from the boss portion at the mechanically-weaker portion as a result of an acting force larger than a predetermined value in the pedal closing direction being applied to the rotating member;
• the rotating member is composed of a pedal-side rotating member to be rotated together with the pedal shaft;
• the biasing member is composed of a pedal-side biasing member for biasing the pedal-side rotating member in the pedal closing direction;
• the boss portion is composed of a pedal-side boss portion to be fixed to an outer periphery of the pedal shaft;
• the biasing-member holding portion is composed of a pedal-side biasing-member holding portion for holding one end of the pedal-side biasing member;
• the pedal-side rotating member has a stopper arm extending from the pedal-side biasing-member holding portion in the radial-outward direction opposite to the pedal-side boss portion, the stopper arm being configured to contact with an inner wall surface of the supporting body due to movement of the acceleration pedal to an acceleration fully-closed position;
• the pedal-side biasing-member holding portion is configured to be broken away from the pedal-side boss portion at the mechanically-weaker portion as a result of the acting force larger than the predetermined value in the pedal closing direction being applied to the pedal-side rotating member;
• and
• the following expression is satisfied:
• Z1<Z2×(L1/L2)
• wherein
• Z1 is a modulus of section of the mechanically-weaker portion;
• Z2 is a modulus of section of any arbitrary portion, which is any portion of the pedal-side rotating member between the mechanically-weaker portion and the stopper arm;
• L1 is a distance between a contacting point and a mechanically weak point, wherein the contacting point corresponds to a point of the stopper arm to be in contact with the inner wall surface of the supporting body and the mechanically weak point corresponds to a point of the mechanically-weaker portion facing to the inner wall surface of the supporting body;
• and
• L2 is a distance between the contacting point and an arbitrary point, wherein the arbitrary point corresponds to a point of the arbitrary portion facing to the inner wall surface of the supporting body.