Continuously variable transmission and a hydraulic control method thereof

Patent metadata

Field	Value
Publication number	US-9441733-B2
Application number	US-201314405289-A
Country	US
Kind code	B2
Filing date	May 28, 2013
Priority date	Jun 8, 2012
Publication date	Sep 13, 2016
Grant date	Sep 13, 2016

Abstract

A transmission controller determines whether a shift is a kickdown, and when the shift is determined as the kickdown, the target line pressure is increased to a first target pressure corresponding to an input torque to a continuously variable transmission increased by the kickdown; the transmission controller then determines whether the line pressure has reached the first target pressure, and if determined that the line pressure has reached the first target pressure, the target line pressure is increased to a second target pressure higher than the first target pressure.

First claim

The invention claimed is:

1. A continuously variable transmission that includes a primary pulley, a secondary pulley and a power transmission member wound between the pulleys and shifts by changing a groove width of each of the pulleys by changing a primary pressure supplied to the primary pulley and a secondary pressure supplied to the secondary pulley, the continuously variable transmission comprising:
an oil pump driven by an engine;
a line pressure regulator valve which is a drain regulator valve that reduces a discharge pressure of the oil pump to regulate a line pressure which is a source pressure of the primary pressure and the secondary pressure, the line pressure regulator valve including a spool on whose edges a signal pressure corresponding to a target line pressure and the line pressure are acted and which opens and closes a drain port in accordance with a stroke, and a spring that biases the spool;
a kickdown determining unit adapted to determine whether a shift is a kickdown;
a first pressure increasing unit adapted to increase the target line pressure to a first target pressure corresponding to an input torque to the continuously variable transmission that increases by the kickdown, when the shift is determined as the kickdown;
a pressure increasing determining unit adapted to determine whether the line pressure has reached the first target pressure; and
a second pressure increasing unit adapted to increase the target line pressure to a second target pressure higher than the first target pressure, when the line pressure is determined as reaching the first target pressure.

2. The continuously variable transmission according to claim 1 , wherein the second pressure increasing unit maintains the target line pressure at the second target pressure for a predetermined time.

3. The continuously variable transmission according to claim 2 , wherein after the target line pressure is maintained at the second target pressure for a predetermined time, the second pressure increasing unit reduces the target line pressure in a predetermined ramp gradient.

4. The continuously variable transmission according to claim 1 , wherein when the line pressure is determined as reaching the first target pressure and the drain port is determined as being closed by the spool as a result of increasing the target line pressure by the first pressure increasing unit, the second pressure increasing unit increases the target line pressure to the second target pressure higher than the first target pressure.

5. The continuously variable transmission according to claim 1 , wherein the first pressure increasing unit increases the secondary pressure together with increasing the line pressure.

6. A method of a controlling a continuously variable transmission according to claim 1 , the method comprising:
determining whether the shift is the kickdown;
increasing the target line pressure to the first target pressure corresponding to the input torque to the continuously variable transmission that increases by the kickdown, when the shift is determined as the kickdown;
determining whether the line pressure has reached the first target pressure; and
increasing the target line pressure to the second target pressure higher than the first target pressure, when the line pressure is determined as reaching the first target pressure.

7. A continuously variable transmission that includes a primary pulley, a secondary pulley and a power transmission member wound between the pulleys and shifts by changing a groove width of each of the pulleys by changing a primary pressure supplied to the primary pulley and a secondary pressure supplied to the secondary pulley, the continuously variable transmission comprising:
an oil pump driven by an engine;
a line pressure regulator valve which is a drain regulator valve that reduces a discharge pressure of the oil pump to regulate a line pressure which is a source pressure of the primary pressure and the secondary pressure, the line pressure regulator valve including a spool on whose edges a signal pressure corresponding to a target line pressure and the line pressure are acted and which opens and closes a drain port in accordance with a stroke, and a spring that biases the spool;
kickdown determining means determining whether a shift is a kickdown;
first pressure increasing means for increasing the target line pressure to a first target pressure corresponding to an input torque to the continuously variable transmission that increases by the kickdown, when the shift is determined as the kickdown;
pressure increasing determining means for determining whether the line pressure has reached the first target pressure; and
second pressure increasing means for increasing the target line pressure to a second target pressure higher than the first target pressure, when the line pressure is determined as reaching the first target pressure.

Assignees

• Jatco Ltd
• Nissan Motor

Inventors

• Takahashi Seiichiro
• Eguchi Takashi
• Utagawa Tomohiro
• Mizuochi Tomoyuki
• Nobu Hisao
• Sakakibara Kenji
• Ikeda Takahiro
• Shimizu Masayuki

Classifications

• F16H2061/66277

  by optimising the clamping force exerted on the endless flexible member · CPC title

• F16H59/20

  Kickdown · CPC title

• F16H61/66272 Primary

  characterised by means for controlling the torque transmitting capability of the gearing · CPC title

• F16H9/125

  characterised by means for controlling the geometrical interrelationship of pulleys and the endless flexible member, e.g. belt alignment or position of the resulting axial pulley force in the plane perpendicular to the pulley axis · CPC title