Method for controlling an engine installed with continuously variable transmission

Claim 1

A method for controlling the RPM of an engine in a motor vehicle using a continuously variable transmission, the transmission having a driving pulley comprising a fixed member and a movable member, the movable member being actuated by a hydraulic cylinder to form a V-shaped opening between the movable member and the fixed member, a driven pulley with another fixed member and another movable member, the another movable member being similarly actuated by another hydraulic cylinder to form a similar V-shaped opening between the another movable member and the another fixed member, and a flexible belt member spanning the pulleys so that the diameter of the pulleys can be varied with regard to each other so that different transmitting ratios can be obtained, the method comprising the steps of: detecting a change in an amount of throttle opening in a throttle means on the engine; detecting an actual RPM of the engine at a point immediately after a change occurs in the amount of throttle opening in the throttle means: selecting an intermediate engine RPM and changing the detected actual RPM to the selected intermediate RPM when the continuously variable transmission undergoes a transient shifting condition, the transient shifting condition being generated by the change in the amount of throttle opening, the selected engine RPM being intermediate in value between an engine RPM which would occur under steady state conditions given the amount of throttle opening and the detected actual RPM; and gradually changing the selected intermediate engine RPM to the steady RPM corresponding to the amount of throttle opening.

Claim 2

A method for controlling the RPM of an engine in a motor vehicle using a continuously variable transmission, the transmission having a driving pulley comprising a fixed member and a movable member, the movable member being actuated by a hydraulic cylinder to form a V-shaped opening between the movable member and the fixed member, a driven pulley with another fixed member and another movable member, the another movable member being similarly actuated by another hydraulic cylinder to form a similar V-shaped opening between the another movable member and the another fixed member, and a flexible belt member spanning the pulleys so that the diameter of the pulleys can be varied with regard to each other so that different transmitting ratios can be obtained, the method comprising the steps of: detecting a change in an amount of throttle opening in a throttle means on the engine; detecting an actual RPM of the engine at a point immediately after a change occurs in the amount of throttle opening in the throttle means: selecting an intermediate engine RPM and changing the detected actual RPM to the selected intermediate RPM when the continuously variable transmission undergoes a transient shifting condition, the transient shifting condition being generated by the change in the amount of throttle opening, the selected engine RPM being intermediate in value between an engine RPM which would occur under steady state conditions given the amount of throttle opening and the detected actual RPM; and gradually changing the selected intermediate engine RPM to the steady RPM corresponding to the amount of throttle opening.

Claim 4

A method for controlling the RPM of an engine in a motor vehicle using a continuously variable transmission, the transmission having a driving pulley comprising a fixed member and a movable member, the movable member being actuated by a hydraulic cylinder to form a V-shaped opening between the movable member and the fixed member, a driven pulley with another fixed member and another movable member, the another movable member being similarly actuated by another hydraulic cylinder to form a similar V-shaped opening between the another movable member and the another fixed member, and a flexible belt member spanning the pulleys so that the diameter of the pulleys can be varied with regard to each other so that different transmission ratios can be obtained, the method comprising the steps of: detecting a change in an amount of throttle opening in a throttle means on the engine; determining a steady state RPM corresponding to the amount of throttle opening; detecting an actual RPM of the engine at a point immediately after a change occurs in the amount of throttle opening in the throttle means; calculating the magnitude of the difference between the steady state RPM and the detected actual RPM.

Claim 5

A method for controlling the RPM of an engine in a motor vehicle using a continuously variable transmission, the transmission having a driving pulley comprising a fixed member and a movable member, the movable member being actuated by a hydraulic cylinder to form a V-shaped opening between the movable member and the fixed member, a driven pulley with another fixed member and another movable member, the another movable member being similarly actuated by another hydraulic cylinder to form a similar V-shaped opening between the another movable member and the another fixed member, and a flexible belt member spanning the pulleys so that the diameter of the pulleys can be varied with regard to each other so that different transmission ratios can be obtained, the method comprising the steps of: detecting a change in an amount of throttle opening in a throttle means on the engine; determining a steady state RPM corresponding to the amount of throttle opening; detecting an actual RPM of the engine at a point immediately after a change occurs in the amount of throttle opening in the throttle means; calculating the magnitude of the difference between the steady state RPM and the detected actual RPM.

Claim 12

A method for controlling an actual engine speed in a motor vehicle comprising a continuously variable transmission, the transmission having a driving pulley comprising a fixed member and a movable member, the movable member being actuated by a hydraulic cylinder to form a V-shaped opening between the movable member and the fixed member, a driven pulley with another fixed member and another movable member, the another movable member being actuated by another hydraulic cylinder to form another V-shaped opening between the another movable member and the another fixed member, a flexible belt member spanning the pulleys, and an electronic control means, the electronic control means includes a memory means for storing a relationship between a plurality of desired engine speeds and throttle openings, said electronic control means for controlling pressure in the hydraulic cylinders according to an optimal desired engine speed of the engine, the method comprising the steps of: detecting first and second amounts of a throttle opening, the first amount of the throttle opening detected being an initial amount before a change in the throttle opening, the second amount of the throttle opening being an amount after the change in the throttle opening; determining a first desired engine speed for steady state conditions before said change in the throttle opening and determining a second desired engine speed for steady state conditions after said change in the throttle opening, said first desired engine speed being determined from said detected first amount of said throttle opening in accordance with said relationship stored in said memory means, said second desired engine speed being determined from the detected second amount of said throttle opening in accordance with said relationship stored in said memory means; calculating a difference between said first desired engine speed and said second desired engine speed; comparing said difference between said first desired engine speed and said second desired engine speed with a predetermined value; adjusting said actual engine speed in accordance with said comparison, whereby when said difference is smaller than said predetermined value, said actual engine speed is adjusted to approach said second desired engine speed gradually, and when said difference is larger than said predetermined value, said actual engine speed is immediately adjusted to a transient value and then is adjusted to approach said second desired engine speed gradually.

Claim 13

A method for controlling an actual engine speed in a motor vehicle comprising a continuously variable transmission, the transmission having a driving pulley comprising a fixed member and a movable member, the movable member being actuated by a hydraulic cylinder to form a V-shaped opening between the movable member and the fixed member, a driven pulley with another fixed member and another movable member, the another movable member being actuated by another hydraulic cylinder to form another V-shaped opening between the another movable member and the another fixed member, a flexible belt member spanning the pulleys, and an electronic control means, the electronic control means includes a memory means for storing a relationship between a plurality of desired engine speeds and throttle openings, said electronic control means for controlling pressure in the hydraulic cylinders according to an optimal desired engine speed of the engine, the method comprising the steps of: detecting first and second amounts of a throttle opening, the first amount of the throttle opening detected being an initial amount before a change in the throttle opening, the second amount of the throttle opening being an amount after the change in the throttle opening; determining a first desired engine speed for steady state conditions before said change in the throttle opening and determining a second desired engine speed for steady state conditions after said change in the throttle opening, said first desired engine speed being determined from said detected first amount of said throttle opening in accordance with said relationship stored in said memory means, said second desired engine speed being determined from the detected second amount of said throttle opening in accordance with said relationship stored in said memory means; calculating a difference between said first desired engine speed and said second desired engine speed; comparing said difference between said first desired engine speed and said second desired engine speed with a predetermined value; adjusting said actual engine speed in accordance with said comparison, whereby when said difference is smaller than said predetermined value, said actual engine speed is adjusted to approach said second desired engine speed gradually, and when said difference is larger than said predetermined value, said actual engine speed is immediately adjusted to a transient value and then is adjusted to approach said second desired engine speed gradually.