Parking brake mechanism for motor vehicle equipped with power transmission with torque converter

• US 4,200,002 A
• Filed: 07/27/1977
• Issued: 04/29/1980
• Est. Priority Date: 07/28/1976
• Status: Expired due to Term

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Takahashi, Kotei
• Primary Examiner(s): Davis, Albert W.
• Assistant Examiner(s): Ratliff, Jr., Wesley S.
• Application Number:
  US05/819,451
• Time in Patent Office: 1,007 Days
• Field of Search: 192/4 A, 74/462, 74/577, 74/575, 74/530, 188/69, 188/60, 188/71.4, 188/71.7
• US Class Current: 74/530
• CPC Class Codes: B60T 1/005 by locking of wheel or transmission rotation
• CPC Class Codes: F16H 63/3416 Parking lock mechanisms or brakes in the transmission
• CPC Class Codes: Y10T 74/20654 Gear

Abstract

A tooth formed on a brake pawl has, at a portion facing the outer peripheral surface of a brake gear coaxially mounted on the output shaft of the transmission, first and second inclined surfaces which are bounded by an intersectional line parallel to the axis of the output shaft. The inclination angle of each surface with respect to a tangent line passing through a point where the intersectional line is in contact with a circular path swept out by the outer peripheral surface of teeth formed on the brake gear is greater than zero degrees. With this, the brake pawl is pushed way from its engaged condition due to collisions between shoulder portions of the teeth and one of the first and second inclined surfaces above a predetermined vehicle speed.

Claims

1. A parking brake mechanism in a motor vehicle transmission having a transmission output shaft, comprising a brake gear coaxially mounted on said output shaft for rotation therewith, said brake gear including at the periphery thereof a plurality of external teeth, a brake pawl mounted for rotation about an axis parallel to the axis of said output shaft and carrying thereon a tooth engageable with a gap formed between any corresponding two of said teeth when biased to lean toward said brake gear, and a parking cam for urging said brake pawl to lean toward said brake gear when biased in a given direction, wherein said tooth of said brake pawl includes thereon first, second, third and fourth surfaces at a portion thereof which substantially enters said gap of said brake gear when said tooth is engaged with said gap for locking said brake gear, said first and second surfaces being inclined with respect to each other and bounded by an intersectional line parallel with the axis of said output shaft and having at opposite positions with respect to said intersectional line respective edges away from which said third and fourth surfaces extend, the inclination angle of each of said first and second surfaces with respect to a tangent line passing through an imaginary point at which said intersectional line is in contact with a circular path swept out by the outer peripheral surface of said teeth being greater than zero degrees, the respective inclination angles of said third and fourth surfaces with respect to said first and second surfaces being selected so that ridges by which said first and third surfaces, and said second and fourth surfaces are bounded are substantially received in said gap when said tooth enters said gap to such a degree as to achieve locking of said brake gear.