Accumulator arrangement for automatic transmission control circuit

• US 5,038,637 A
• Filed: 10/31/1988
• Issued: 08/13/1991
• Est. Priority Date: 10/30/1987
• Status: Expired due to Term

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Sugano, Kazuhiko
• Primary Examiner(s): Diehl, Dwight
• Application Number:
  US07/264,701
• Time in Patent Office: 1,016 Days
• Field of Search: 74/867, 74/868, 74/869
• US Class Current: 477/150
• CPC Class Codes: F16H 2061/0466 Smoothing shift shock by apply or release of band brake servos, e.g. overlap control of band brake and a clutch or vice versa
• CPC Class Codes: F16H 61/061 using electric control means
• CPC Class Codes: F16H 61/067 using an accumulator

Abstract

A one-way valve is arranged with an accumulator in a manner wherein the discharging of the accumulator is restricted. During upshifting, the stroking of a band brake servo in a release direction is induced before the charging stroke of the accumulator and the appropriate timing of the engagement of a high clutch and the disengagement of a band brake is induced. During downshifting, the pressure which is prevailing in the conduit interconnecting the two friction elements is allowed to drop rapidly during the initial stage of the shift due to the provision of the one-way orifice and allows the torque transmission capacity of the clutch to quickly reduce while inducing the stroking of the band brake servo in an engaging direction before the discharge stroke of the accumulator.

Claims

1. In a transmission

first and second friction elements, said first friction element being arranged to be engaged when supplied with hydraulic fluid, said second friction element having a release chamber and arranged so that when said release chamber is supplied with hydraulic fluid said second friction element is conditioned to assume a disengaged condition;

an accumulator;

a shift valve;

conduit means for fluidly communicating said shift valve with said first friction element, said release chamber of said second friction element and said accumulator, said shift valve having a first position wherein hydraulic fluid is supplied to said first friction element, said release chamber and said accumulator via said conduit means and a second position wherein said conduit means is connected to a drain;

a fixed orifice disposed in said conduit means, said fixed orifice restricting communication between said shift valve, and said first friction element, said release chamber and said accumulator; and

a one-way orifice disposed in said conduit means in a manner to permit hydraulic fluid to be supplied freely to said accumulator and for the discharge of hydraulic fluid from said accumulator to be resisted, said one way orifice being arranged between said accumulator and both of said first and second friction elements.

2. In a transmission

a clutch, said clutch being arranged to be engaged when supplied with hydraulic fluid and to produce a third speed gear ratio when engaged;

a brake, said brake having a release chamber and first and second apply chambers, said brake being arranged so that when said release chamber is supplied with hydraulic fluid said brake is conditioned to assume a disengaged position, said brake being arranged to produce a second gear when engaged and said clutch is released;

a servo release accumulator;

a 2-3 shift valve;

conduit means for fluidly communicating said shift valve with said clutch, said release chamber and said accumulator, said shift valve having a first position wherein hydraulic fluid is supplied to said clutch, said release chamber and said accumulator via said conduit means and a second position wherein said conduit means is connected with a drain;

a fixed orifice disposed in said conduit means, said fixed orifice being disposed between said shift valve, and said clutch, between said shift valve and said release chamber and between said shift valve and said accumulator; and

a one-way orifice disposed in said conduit means, between both of said clutch and the release chamber, of said brake and the accumulator, said one-way orifice being arranged in a manner to permit hydraulic fluid to be supplied freely to said accumulator and for the discharge of hydraulic fluid from said accumulator to be resisted.

3. In a transmission

first and second friction elements, said first friction element being arranged to be engaged when supplied with hydraulic fluid, said second friction element having a release chamber and arranged so that when said release chamber is supplied with hydraulic fluid said second friction element is conditioned to assume a disengaged condition;

an accumulator;

a shift valve;

conduit means for fluidly communicating said shift valve with said first friction element, said release chamber of said second friction element and said accumulator, said shift valve having a first position wherein hydraulic fluid is supplied to said first friction element, said release chamber and said accumulator via said conduit means and a second position wherein said conduit means is connected to a drain;

a fixed orifice disposed in said conduit means, said fixed orifice restricting communication between said shift valve, and said first friction element, said release chamber and said accumulator; and

a one-way orifice disposed in said conduit means in a manner to permit hydraulic fluid to be supplied freely to said accumulator and for the discharge of hydraulic fluid from said accumulator to be resisted and wherein said accumulator comprises;

a stepped piston reciprocatively disposed in a stepped bore, said stepped piston having a first large diameter land and a second small diameter land, said first and second lands defining first, second and third chamber in said bore, said first chamber being fluidly communicated with said conduit means, said second chamber being essentially annular in shape and communicated with a source of back pressure, said source of back pressure being arranged to supply hydraulic fluid under pressure when said transmission is conditioned to produce forward speed, said third chamber being supplied with hydraulic fluid under pressure when said transmission is conditioned to produce reverse gear, said first chamber housing a spring which tends to bias said piston in a direction which minimizes the volume of said third chamber.

4. In a transmission

a first friction element, said first element being arranged to be engaged when supplied with hydraulic fluid;

a shift valve;

a first conduit leading from said shift valve to said first friction element;

a fixed orifice disposed in said first conduit;

a second friction element, said second friction element having a release chamber and arranged so that when said release chamber is supplied with hydraulic fluid said second friction element is conditioned to assume a disengaged condition;

a second conduit which leads from said first conduit to said release chamber of said second friction element, said second conduit communicating with said first conduit at a location between said first friction element and said fixed orifice;

an accumulator;

a third conduit which fluidly communicates with one of said first and second conduits at a predetermined location, said third conduit leading to and fluidly communicating with said accumulator, said fixed orifice being located between said predetermined location and said shift valve; and

a one-way orifice disposed in said third conduit, said one-way orifice permitting hydraulic fluid to be supplied freely to said accumulator and for the discharge of hydraulic fluid from said accumulator to be resisted.

5. In a transmission

a shift valve;

a first friction element, said first friction element being fluidly communicated with said shift valve and arranged so as to be engaged when supplied with hydraulic fluid therefrom;

a second friction element, said second friction element having a release chamber which is fluidly communicated with said shift valve and arranged so that when said release chamber is supplied with hydraulic fluid from said shift valve said second friction element is conditioned to assume a disengaged condition;

an accumulator, said accumulator having a first chamber which is fluidly communicated with said first friction element and the release chamber of said second friction element, a second chamber which is fluidly communicated with a source of back pressure only when the transmission is conditioned to produce forward drive and a third chamber which is fluidly communicated with a source of back pressure when the transmission is conditioned to produce a reverse drive; and

a one-way orifice, said one-way orifice permitting hydraulic fluid to be supplied freely to the first chamber of said accumulator and for the discharge of hydraulic fluid from the first chamber of said accumulator to be resisted.