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Title: Automatic transmission hydraulic control throttle valve
Claims: What is claimed is: 1. A throttle valve of a hydraulic control system of an automatic power transmission of a vehicle driven by a prime mover, comprising a lever pivotably connected at a first portion with a prime mover acceleration control member, a valve spool pivotably connected with said lever at a second portion which is spaced from said first portion along the length of said lever and having a constant neutral position, a passageway into and from which hydraulic fluid is delivered and discharged to increase and reduce the hydraulic pressure in said passageway when said valve spool is moved from said neutral position in axial, opposite directions, the hydraulic pressure in said passageway being equal to a throttle pressure depending on the position of said control member when said valve spool is in said neutral position, a piston pivotably connected with said lever at a third portion which is spaced from said first and second portions along the length of said lever, a spring urging said piston to prevent said piston from being moved by said lever when said control member is moved in a prime mover output increasing direction, said piston communicating with said passageway and being biased by the hydraulic pressure in said passageway against the action of said spring, said lever being rotatable around said piston by said control member to move said valve spool in said opposite directions when said control member is moved in prime mover output increasing and reducing directions, said piston being moved in response to the hydraulic pressure in said passageway lower and higher than said throttle pressure to move said valve spool from said neutral position in said opposite directions to cause increase and reduction in the hydraulic pressure in said passageway to said throttle pressure. 2. A throttle valve as claimed in claim 1, in which force differential biasing said valve spool to withstand the force of said lever tending to move said valve spool is approximately zero. 3. A throttle valve as claimed in claim 1, in which said valve spool is constructed to be spaced from said neutral position and to be in a position to prevent delivery of a hydraulic pressure into said passageway until said control member is moved into a predetermined output producing position. 4. A throttle valve as claimed in claim 1, in which said piston is maintained in the utmost position by the hydraulic pressure in said passageway overcoming the action of said spring and said valve spool is maintained in a position to maintain the hydraulic pressure in said conduit at a hydraulic pressure delivered to said slide valve, by said lever rotated around said piston by said control member, when the same is moved beyond the vicinity of the maximum output generating position. 5. A throttle valve as claimed in claim 1, further comprising a valve body formed with a valve chamber and a bore therein, said valve chamber being provided with an inlet port through which a hydraulic pressure is delivered into said valve chamber, an outlet port through which said passageway open into said valve chamber and a drain port, in which said valve spool is slidably fitted in said valve chamber and has spaced first and second lands with an identical diameter, and an annular groove which is formed therebetween and which communicates with said inlet port, said second land registering with said outlet port when said valve spool is in said neutral position and opening said outlet port to provide communication between said inlet and outlet ports when said valve spool is moved from said neutral position in one direction and to provide communication between said outlet and drain ports when said valve spool is moved from said neutral position in another direction, and in which said piston is slidably fitted in said bore and said spring is disposed between said piston and an end wall of said bore remote from said lever, said bore being provided at an end adjacent to said lever with a port through which said passageway opens into said bore to supply the hydraulic pressure into a space between said piston and the lastmentioned end of said bore, said piston being in a position depending on the position of said control member when said valve spool is in said neutral position. Other info: Inventors: Iijima, Tetsuya (Tokyo, JA) Application Number: 511689 Filing Date: 1974-10-03 Publication_date: 1976-03-02 Assignee: Nissan Motor Co., Ltd. (Yokohama, JA) Primary Class(es): 137/102 137/115.16, 137/628, 477/156 Other Classes: US Patent Ref:
Other Refs: Primary Examiner: Schwadron, Martin P. Assistant Examiner: Miller, Robert J. Attorney: |
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