Hydraulic control system for vehicle

Patent metadata

Field	Value
Publication number	US-2016017994-A1
Application number	US-201314773021-A
Country	US
Kind code	A1
Filing date	Jun 5, 2013
Priority date	Mar 6, 2013
Publication date	Jan 21, 2016
Grant date	—

Abstract

A hydraulic control system for a vehicle having a continuously variable transmission in which a torque transmitting capacity thereof is changed hydraulically, and an engagement device which is connected to the continuously variable transmission in series and in which a torque transmitting capacity thereof is changed hydraulically. The hydraulic control system comprises a selecting means that selects a command pattern for setting an engagement pressure of the engagement device out of a plurality of patterns when an initial pressure is lower than a steady pressure for a normal running of the vehicle. The selecting means is configured to select the command pattern in such a manner that the torque transmitting capacity of the engagement device does not exceeds the torque transmitting capacity of the continuously variable transmission, based on at least any of conditions of the initial pressure that is lowered to be lower than the steady pressure, and a rotational speed of the continuously variable transmission.

First claim

1 . A hydraulic control system for a vehicle comprising a continuously variable transmission in which a torque transmitting capacity thereof is changed hydraulically, and an engagement device which is connected to the continuously variable transmission in series and in which a torque transmitting capacity thereof is changed hydraulically, comprising:
a control unit that is configured to select a command pattern for setting an engagement pressure of the engagement device out of a plurality of patterns when an initial pressure is lower than a steady pressure for a normal running of the vehicle; and wherein the control unit is further configured to select the command pattern in such a manner that the torque transmitting capacity of the engagement device does not exceed the torque transmitting capacity of the continuously variable transmission, based on at least any of conditions of the initial pressure that is lowered to be lower than the steady pressure, and a rotational speed of the continuously variable transmission.

2 . The hydraulic control system for a vehicle as claimed in claim 1 , wherein the control unit is further configured to select the command pattern based on a difference between rotational speeds of an input rotary member and an output rotary member of the engagement device.

3 . The hydraulic control system for a vehicle as claimed in claim 1 , wherein the control unit is further configured to select the command pattern based on a braking demand and a road gradient.

4 . The hydraulic control system for a vehicle as claimed in claim 1 , further comprising:
a prime mover that generates a driving force, and a fluid coupling that is connected to the prime mover to deliver the driving force to the engagement device, and wherein the control unit is further configured to determine a commencement of an engagement of the engagement device based on a fact that an output speed of the fluid coupling is lowered under a condition that the initial pressure is raised to a level of the steady pressure.

5 . The hydraulic control system for a vehicle as claimed in claim 4 ,
wherein the control unit is further configured to increase the engagement pressure of the engagement device continuously in case a commencement of engagement of the engagement device is determined.

6 . The hydraulic control system for a vehicle as claimed in claim 1 , wherein the engagement device includes a clutch and a brake of a torque reversing device that is adapted to reverse rotational directions of an input shaft and an output shaft.

7 . The hydraulic control system for a vehicle as claimed in claim 1 , further comprising:
a mechanical oil pump that is driven by a power for propelling the vehicle to discharge oil.

8 . The hydraulic control system for a vehicle as claimed in claim 7 , further comprising:
an electric oil pump that is driven by a motor to discharge oil and in which a capacity thereof is smaller than that of the mechanical oil pump.

9 . The hydraulic control system for a vehicle as claimed in claim 7 , further comprising:
a regulator valve that regulates hydraulic pressure in a passage for the oil discharged from the mechanical oil pump; and wherein the initial pressure includes hydraulic pressure in the passage regulated by the regulator valve.

10 . The hydraulic control system for a vehicle as claimed in claim 9 , wherein the oil discharged from the passage through the regulator valve when the hydraulic pressure in the passage is high is delivered to a low pressure site where a level of a required pressure is lower than a level of the pressure required by the engagement device or the continuously variable transmission.

Assignees

• Toyota Motor Co Ltd

Inventors

• Suzumura Kyohei
• Toyoda Shinya
• Ishiizumi Kazuya
• Hino Akira
• Kojima Sei

Classifications

• F16D2500/3101

  Detection of a brake actuation by a sensor on the brake · CPC title

• F16H61/66272 Primary

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

• F16H61/688

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

• F16D48/066

  Control of fluid pressure, e.g. using an accumulator (F16D48/062, F16D48/068 take precedence) · CPC title

• F16D2500/1088

  CVT · CPC title