Hydraulic circuit used for automatic transmission of vehicle having automatic engine-stop system, and oil-pressure control system and method

• US 6,390,947 B1
• Filed: 07/28/2000
• Issued: 05/21/2002
• Est. Priority Date: 07/29/1999
• Status: Expired due to Term

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Aoki, Takashi, Shimabukuro, Eijiro
• Primary Examiner(s): ESTREMSKY, SHERRY LYNN
• Application Number:
  US09/628,019
• Time in Patent Office: 662 Days
• Field of Search: 477/3, 477/45, 477/156
• US Class Current: 477/3
• CPC Class Codes: B60W 10/04 including control of propulsion units
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/101 Infinitely variable gearings
• CPC Class Codes: B60W 30/18 Propelling the vehicle
• CPC Class Codes: B60W 30/1819 Propulsion control with control means using analogue circuits, relays or mechanical links
• CPC Class Codes: F16H 61/0025 Supply of control fluid; Pumps therefore
• CPC Class Codes: F16H 61/0031 using auxiliary pumps, e.g. pump driven by a different power source than the engine
• CPC Class Codes: F16H 61/66 specially adapted for continuously variable gearings control of exclusively fluid gearing F16H61/38
• CPC Class Codes: F16H 61/66272 characterised by means for controlling the torque transmitting capability of the gearing

Abstract

A hydraulic circuit for controlling the oil pressure supplied to an automatic transmission of a vehicle which has a mechanical oil pump, driven by an engine, for supplying hydraulic oil to the automatic transmission and which has an automatic engine-stop system is disclosed, by which the rise speed of the oil pressure for driving the automatic transmission can be increased when the engine is restarted, and the delay of the response for starting the vehicle can be decreased. In the hydraulic circuit, a bypass passage for connecting the suction side and the supply side of the mechanical oil pump is provided; and an electric oil pump is connected to the bypass passage in a manner such that the mechanical oil pump and the electric oil pump are arranged in parallel.

Claims

1. A hydraulic circuit comprising:

a control section for controlling the oil pressure supplied to an automatic transmission of a vehicle which has a single-directional mechanical oil pump, driven by an engine, for supplying hydraulic oil to the automatic transmission and which has an automatic engine-stop system, wherein the control section comprises;

a bypass passage for connecting the suction side and the supply side of the mechanical oil pump; and

an electric oil pump connected to the bypass passage in a manner such that the mechanical oil pump and the electric oil pump are arranged in parallel.

2. A hydraulic circuit as claimed in claim 1, comprising:

a check valve, inserted in the bypass passage at the supply side of the electric oil pump, for preventing back flow of the hydraulic oil from the mechanical oil pump to the electric oil pump; and

a first pressure adjusting device, provided between the check valve and the electric oil pump, for adjusting a discharge pressure of the electric oil pump.

3. A hydraulic circuit as claimed in claim 2, further comprising:

a second pressure adjusting device for adjusting the discharge pressure of the electric oil pump, where the set pressure of the first pressure adjusting device is smaller than the set pressure of the second pressure adjusting device.

4. A hydraulic circuit as claimed in claim 2, wherein the bypass passage, the electric oil pump, the check valve, and the first pressure adjusting device are added and attached to an oil path of the automatic transmission as a unit.

5. An oil-pressure control system for controlling a hydraulic circuit as claimed in any one of claims 1 to 4, the system comprising:

an electric oil pump controlling section for activating the electric oil pump if the section receives an engine stop command for stopping the engine, and stopping the electric oil pump if the section receives an engine start command for restarting the engine, wherein the electric oil pump controlling section stops the electric oil pump when a predetermined time has elapsed after the engine restart.

6. An oil-pressure control system for controlling a hydraulic circuit as claimed in any one of claims 1 to 4, the system comprising:

an electric oil pump controlling section for activating the electric oil pump if the section receives an engine stop command for stopping the engine, and stopping the electric oil pump if the section receives an engine start command for restarting the engine, wherein after the engine restart, the electric oil pump controlling section determines whether the combustion in the engine has reached a specific maximum level, and stops the electric oil pump when it is determined that the combustion in the engine has reached the specific maximum level.

7. An oil-pressure control method for controlling a hydraulic circuit as claimed in any one of claims 1 to 4, the method comprising the step of:

activating the electric oil pump if an engine stop command for stopping the engine is received, and stopping the electric oil pump if an engine start command for restarting the engine is received, wherein the electric oil pump is stopped when a predetermined time has elapsed after the engine restart.

8. An oil-pressure control method for controlling a hydraulic circuit as claimed in any one of claims 1 to 4, the method comprising the step of:

activating the electric oil pump if an engine stop command for stopping the engine is received, and stopping the electric oil pump if an engine start command for restarting the engine is received, wherein after the engine restart, it is determined whether the combustion in the engine has reached a specific maximum level, and the electric oil pump is stopped when it is determined that the combustion in the engine has reached the specific maximum level.