US 5,720,692 AGranted

Method and apparatus for controlling a continuously variable transmission

AssigneeUnisia Jecs Corporation

InventorMasuo Kashiwabara

Life of this patent

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Abstract

In order to optimize the speed change control of a continuously variable transmission, a necessary minimum primary pressure (Ppmin) for achieving a target speed change ratio is computed, and also a necessary minimum line pressure (Plmin) for the non occurrence of slippage between a secondary pulley 5 and a belt 6 is computed, and a required speed change ratio line pressure (Plratio) which can realize a target speed change ratio without slippage on the primary pulley 4 side is computed. The highest of these is then selected. The selected line pressure (Pl base) is then corrected by a transition line pressure (Pl add) determined from engine torque (TQ.sub.ENG) and speed change speed (SV), to obtain a final output line pressure (Plprs) which is then used to control a secondary pulley actuator 5a. In this way, speed change control can be optimized, for example by controlling slipping of the belt 6 at the time of rapid speed change.

Claims14

Dependent claims

A method of controlling a continuously variable transmission comprising a drive side rotating member which receives a rotation force from a drive source, a driven side rotating member, and a drive transmission member disposed therebetween for transmitting drive between both members, with a speed change ratio between said drive side rotating member and said driven side rotating member able to be steplessly set by steplessly changing a drive side contact radius (a distance of a contact position of said drive side rotating member and said drive transmission member from the rotation axis), and a driven side contact radius (a distance of a contact position of said driven side rotating member and said drive transmission member from the rotation axis) relative to each other, said method including the steps of:

in a rapid speed change line pressure control step, temporarily increasing a line pressure temporarily at a rapid speed change line pressure control step to press said driven side rotating member against said drive transmission member when a rapid speed change is detected, to thereby temporarily increase a contact pressure between said drive transmission member and said drive side rotating member or said driven side rotating member, so that slipping does not occur between said drive transmission member and said drive side rotating member or said driven side rotating member;
and
in a first pressure setting step, setting the line pressure controlled in said rapid speed change line pressure control step higher in accordance with an increase in the input torque which is input to said drive side rotating member.

A method of controlling a continuously variable transmission comprising a drive side rotating member which receives a rotation force from a drive source, a driven side rotating member, and a drive transmission member disposed therebetween for transmitting drive between both members, with a speed change ratio between said drive side rotating member and said driven side rotating member able to be steplessly set by steplessly changing a drive side contact radius (a distance of a contact position of said drive side rotating member and said drive transmission member from the rotation axis), and a driven side contact radius (a distance of contact position of said driven side rotating member and said drive transmission member from the rotation axis) relative to each other, said method including the steps of:

in a rapid speed change line pressure control step, temporarily increasing a line pressure temporarily at a rapid speed change line pressure control step to press said driven side rotating member against said drive transmission member when a rapid speed change is detected, to thereby temporarily increase a contact pressure between said drive transmission member and said drive side rotating member or said driven side rotating member, so that slipping does not occur between said drive transmission member and said drive side rotating member or said driven side rotating member;
and
in a second line pressure setting step, setting the line pressure controlled in said rapid speed change line pressure control step higher in accordance with an increase in the rate at which the speed changes.

An apparatus for controlling a continuously variable transmission comprising a drive side rotating member which receives a rotation force from a drive source, a driven side rotating member, and a drive transmission member disposed therebetween for transmitting drive between both members with a speed change ratio between said drive aide rotating member and said driven side rotating member able to be steplessly set by steplessly changing a drive side contact radius (a distance of a contact position of said drive side rotating member and said drive transmission member from the rotation axis), and a driven side contact radius (a distance of a contact position at said driven side rotating member and said drive transmission member from the rotation axis) relative to each other, said apparatus including:

rapid speed change line pressure control means for temporarily increasing a line pressure which presses said driven side rotating member against said drive transmission member when a rapid speed change is detected so as to temporarily increase a contact pressure between said drive transmission member and said drive side rotating member or said driven side rotating member, so that slipping does not occur between said drive transmission member and said drive side rotating member or said driven side rotating member;
and
first line pressure setting means for setting the line pressure controlled by said rapid speed change line pressure control means higher the input torque which is input to said drive side rotating member.

An apparatus for controlling a continuously variable transmission comprising a drive side rotating member which receives a rotation force from a drive source, a driven side rotating member, and a drive transmission member disposed therebetween for transmitting drive between both members, with a speed change ratio between said drive side rotating member and said driven side rotating member able to be steplessly set by steplessly changing a drive side contact radius (a distance of a contact position of said drive side rotating member and said drive transmission member from the rotation axis), and a driven side contact radius (a distance at a contact position of said driven side rotating member and said drive transmission member from the rotation axis) relative to each other, said apparatus including:

rapid speed change line pressure control means for temporarily increasing a line pressure which presses said driven side rotating member against said drive transmission member when a rapid speed change is detected, so as to temporarily increase a contact pressure between said drive transmission member and said drive side rotating member or said driven side rotating member, so that slipping does not occur between said drive transmission member and said drive side rotating member or said driven side rotating member;
and
second line pressure setting means for setting the line pressure controlled by said rapid speed change line pressure control means higher the faster the speed change speed.

Dependencies are inferred from the claim text.

Facts

Application: 08/629,642Filed 9 Apr 1996
Priority: JP 7-08407710 Apr 1995
Granted: 24 Feb 1998
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

F16H 61/6649
Friction gearings: characterised by the means for controlling the torque transmitting capability of the gearing
F16H 61/66272
With endless flexible members: characterised by means for controlling the torque transmitting capability of the gearing
F16H 2061/66281
Characterised by means for controlling the torque transmitting capability of the gearing: by increasing the line pressure at the occurrence of…
F16H
Gearing