Line pressure control method for dual-clutch transmission

Patent metadata

Field	Value
Publication number	US-2020325985-A1
Application number	US-201916539147-A
Country	US
Kind code	A1
Filing date	Aug 13, 2019
Priority date	Apr 9, 2019
Publication date	Oct 15, 2020
Grant date	—

Abstract

A line pressure control method for a dual-clutch transmission (DCT), may include a hydraulic-pressure-decreasing operation of interrupting, by a controller, the supply of current to an electric oil pump and estimating a decrease in a line pressure using a line pressure model based on a pressure accumulator mounted in a hydraulic pressure line, a pump-driving operation of, when the estimated line pressure is equal to or less than a predetermined lower-limit value, driving, by the controller, the electric oil pump, and a hydraulic-pressure-increasing operation of determining, by the controller, the line pressure based on the current supplied to the electric oil pump and to determine whether the determined line pressure is equal to or greater than a predetermined upper-limit value.

First claim

What is claimed is:

1 . A method of controlling a line pressure for a dual-clutch transmission (DCT), the method comprising:
a hydraulic-pressure-decreasing operation of interrupting, by a controller, a supply of current to an electric oil pump and estimating the line pressure which is decreased using a line pressure model based on a pressure accumulator mounted in a hydraulic pressure line; a pump-driving operation of, in a response that the estimated line pressure is equal to or less than a predetermined lower-limit value, driving, by the controller, the electric oil pump to increase the line pressure; and a hydraulic-pressure-increasing operation of determining, by the controller, the line pressure based on the current supplied to the electric oil pump and determining when the determined line pressure is equal to or greater than a predetermined upper-limit value, wherein, in a response that the determined line pressure is equal to or greater than the predetermined upper-limit value, the controller is configured to perform the hydraulic-pressure-decreasing operation.

2 . The method according to claim 1 , further including:
a condition determination operation of determining, by the controller, pressure measurability conditions under which the controller measures the line pressure while applying hydraulic pressure to a non-driving-side clutch during execution of the hydraulic-pressure-decreasing operation; and a model-learning operation of, in a response that the pressure measurability conditions are satisfied, measuring, by the controller, the line pressure while applying hydraulic pressure to the non-driving-side clutch to learn a parameter of the line pressure model.

3 . The method according to claim 2 , wherein the line pressure model is expressed using a following equation:
p L =B 1 e −k 1 t +B 2 where p L denotes the line pressure,

B
1

=

c
A


B

,

c denotes a gas spring constant of the pressure accumulator,
A denotes an area of a piston of the pressure accumulator,

B
=

x
L

e

-

k
1


t

,

x L denotes a displacement of the piston of the pressure accumulator,
k 1 denotes the parameter, and
B 2 denotes a pressure at which a displacement of the piston starts to occur due to a compression pressure of the pressure accumulator.

4 . The method according to claim 3 , wherein in the model-learning operation,
the parameter k 1 is determined by putting the measured line pressure and an inclination at which the line pressure is decreased into a following equation, obtained by differentiating the line pressure model with respect to time:

-

k
1

=

p
L

.

B
1



e

-

k
1


t

and into the line pressure model, and
wherein, in a response that a new value of the parameter k 1 is greater than a parameter of a previous cycle, the line pressure model is updated using the new value of the parameter k 1 .

5 . A method of estimating a decrease in a line pressure, the method including:
estimating, by a controller, the line pressure which is decreased due to stoppage of an electric oil pump, using a line pressure model based on operation of a pressure accumulator mounted in a hydraulic pressure line; determining, by the controller, when pressure measurability conditions under which the controller measures the line pressure while applying hydraulic pressure to a non-driving-side clutch during a decrease in the line pressure are satisfied; and measuring, in a response of determining that the pressure measurability conditions are satisfied, by the controller, the line pressure while applying hydraulic pressure to the non-driving-side clutch to update the line pressure model.

6 . The method according to claim 5 , wherein, in a response that the line pressure decreases to a predetermined lower-limit value or less, the controller is configured to increase the line pressure by driving the electric oil pump.

7 . The method according to claim 5 , wherein the line pressure model is expressed using a following equation:
p L =B 1 e −k 1 t +B 2 where p L denotes the line pressure,

B
1

=

c
A


B

,

c denotes a gas spring constant of the pressure accumulator,
A denotes an area of a piston of the pressure accumulator,

B
=

x
L

e

-

k
1


t

,

x L denotes a displacement of the piston of the pressure accumulator,
k 1 denotes a parameter, and
B 2 denotes a pressure at which a displacement of the piston starts to occur due to a compression pressure of the pressure accumulator.

8 . The method according to claim 7 , wherein the controller is configured to determine the parameter k 1 by putting the measured line pressure and an inclination at which the line pressure is decreased into a following equation, obtained by differentiating the line pressure mod

Assignees

• Hyundai Motor Co Ltd
• Kia Motors Corp

Inventors

• Ko Young Ho
• Lee Hwa Young
• Yoon Young Min
• Kim Jin Sung

Classifications

• F16H61/688

  with two inputs, e.g. selection of one of two torque-flow paths by clutches · CPC title

• F16H61/0025 Primary

  Supply of control fluid; Pumps therefor · CPC title

• F16H61/42

  involving adjustment of a pump or motor with adjustable output or capacity · CPC title

• F16H2061/0093

  using models to estimate the state of the controlled object · CPC title

• F16H61/0031 Primary

  using auxiliary pumps, e.g. pump driven by a different power source than the engine · CPC title