Apparatus and technique for fluid level determination in automatic transmissions

• US 5,282,386 A
• Filed: 09/22/1992
• Issued: 02/01/1994
• Est. Priority Date: 09/22/1992
• Status: Expired due to Term

• Current Assignee: GM Global Technology Operations Incorporated (Motors Liquidation Co. GUC Trust)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Murray, William M., Lee, Ronald A., Niemczyk, Robert T., McCauley, Phillip F., Wilson, Thomas H.
• Primary Examiner(s): YASICH, DANIEL
• Application Number:
  US07/949,165
• Time in Patent Office: 497 Days
• Field of Search: 73/292, 374/142, 340/450, 340/450.3, 340/449, 340/459
• US Class Current: 73/292
• CPC Class Codes: B60W 2050/021 Means for detecting failure or malfunction
• CPC Class Codes: F01M 2250/64 Number of revolutions
• CPC Class Codes: F16H 2061/1208 with diagnostic check cycles; Monitoring of failures
• CPC Class Codes: F16H 57/0447 Control of lubricant levels, e.g. lubricant level control dependent on temperature
• CPC Class Codes: F16H 57/0449 Sensors or indicators for controlling the fluid level
• CPC Class Codes: F16H 59/72 dependent on oil characteristics, e.g. temperature, viscosity
• CPC Class Codes: F16N 2200/10 Temperature
• CPC Class Codes: F16N 2200/12 Viscosity
• CPC Class Codes: F16N 2250/16 Number of revolutions, RPM
• CPC Class Codes: F16N 2250/18 Level
• CPC Class Codes: F16N 2260/04 Oil level
• CPC Class Codes: F16N 2270/10 Level
• CPC Class Codes: F16N 29/00 Special means in lubricating arrangements or systems providing for the indication or detection of undesired conditions; Use of devices responsive to conditions in lubricating arrangements or systems
• CPC Class Codes: G01F 23/804 containing circuits handling parameters other than liquid level

Abstract

An apparatus and technique for fluid level determination in automatic transmissions. The invention employs an electronic control unit in association with an automatic transmission for a vehicle, the electronic control unit receiving data corresponding to transmission oil level, transmission oil temperature, engine speed, transmission speed, and transmission selected range. Upon determining that such data satisfies certain diagnostic tests, the level of transmission fluid within the transmission is determined and adjusted or otherwise normalized to ideal test conditions. The electronic control unit compensates an oil level signal for deviations in oil temperature from an optimum test temperature, and makes further compensation for deviations in engine speed and settling time at the time that the test data is acquired. Additionally, variations in oil density as a function of oil temperature are also compensated.

Claims

1. A method for determining an oil level in a transmission driven by an engine, comprising:

generating a first signal corresponding to an actual transmission oil level and density;

generating a second signal corresponding to actual transmission oil temperature;

determining said actual oil level as a function of said first and second signals;

determining a deviation of actual engine speed from a reference idle engine speed and compensating said determination of actual oil level as a function thereof;

calculating a deviation of said compensated actual oil level from a desired oil level and determining a volume error therefrom;

determining a deviation of said actual oil temperature from a typical operating reference temperature of said transmission oil; and

adjusting said volume error as a function of said deviation of said oil temperature.

2. A method for determining an oil level in a transmission driven by an engine, comprising:

placing said transmission in neutral;

determining an actual oil level within the transmission;

determining a deviation of actual engine speed from a reference idle engine speed and compensating said determination of actual oil level as a function thereof;

determining a period of time from when said transmission was placed in neutral and said determination of actual oil level was made and compensating said determination of actual oil level as a function thereof;

calculating a deviation of said compensated oil level determination from a desired oil level and determining a volume error therefrom;

determining a deviation of actual oil temperature from a typical operating reference temperature of the transmission oil; and

adjusting said volume error as a function of said deviation of said oil temperature.

3. Apparatus for determining an oil level in a transmission driven by an engine, comprising:

means within the transmission for generating a first signal corresponding to an actual transmission oil level and density;

means within the transmission for generating a second signal corresponding to actual transmission oil temperature; and

means connected to said transmission for receiving said first and second signals and determining said actual oil level as a function thereof, determining a deviation of actual engine speed from a reference idle engine speed, determining a period of time between when the transmission is placed in neutral and said determination of actual oil level is made, compensating said determination of actual oil level as a function of said deviation of engine speed and said period of time, calculating a deviation of said compensated oil level from a desired oil level and determining a volume error therefrom, determining a deviation of actual oil temperature from a typical operating reference temperature of the transmission oil, and adjusting said volume error as a function of said deviation of oil temperature.