System and method for detecting leaks in a vapor handling system

• US 5,263,462 A
• Filed: 10/29/1992
• Issued: 11/23/1993
• Est. Priority Date: 10/29/1992
• Status: Expired due to Fees

• Current Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Reddy, Sam R.
• Primary Examiner(s): Cross, E. Rollins
• Assistant Examiner(s): MOULIS, THOMAS N
• Application Number:
  US07/968,132
• Time in Patent Office: 390 Days
• Field of Search: 123/198 D, 123/516, 123/518, 123/520, 123/519
• US Class Current: 123/520
• CPC Class Codes: F02B 77/088 relating to tightness
• CPC Class Codes: F02M 25/0809 Judging failure of purge control system

Abstract

This invention relates to a diagnostic system that detects a leak in an engine vapor handling system by checking whether a predetermined pressure or vacuum is attained in a fuel tank when a corresponding temperature change occurs in the fuel tank while the engine was not running.

Claims

1. A diagnostic system for detecting a leak in a vapor handling system for an engine and having a fuel tank, said diagnostic system comprising:

a means for detecting a temperature change in the fuel tank while the engine is not running,

a means for detecting a pressure change in the fuel tank while the engine is not running,

and a means for determining whether or not a leak exists in the vapor handling system by comparing said temperature change with said pressure change.

2. A diagnostic system for detecting a leak in a vapor handling control system for an engine and having a fuel tank, said diagnostic system comprising:

a means for detecting a predetermined increase of temperature in the fuel tank while the engine is not running,

a means for detecting a predetermined pressure level of the fuel tank while the engine is not running,

and a means to indicate a leak in the vapor handling system if the predetermined pressure level is not attained while the predetermined temperature increase is attained.

3. A diagnostic system for detecting a leak in a vapor handling system for an engine and having a fuel tank, said diagnostic system comprising:

a means for detecting a decrease of temperature in the fuel tank, while the engine is not running,

a means for detecting a predetermined vacuum level in the vapor handling system while the engine is not running,

and a means for indicating a leak in the vapor handling system if the predetermined vacuum level is not attained while a predetermined temperature decrease is attained.

4. A diagnostic system for detecting a leak in a vapor handling system according to claim 3, wherein said means for detecting a predetermined decrease of temperature in the fuel tank comprises:

a device that measures the elapsed time the engine was on before shut off,

and a temperature sensor that measures an engine temperature, wherein a predetermined decrease of temperature is indicated when the elapsed time the engine is on is greater than a selected time and the engine temperature is less than a preselected temperature.

5. A method of detecting a leak in a vapor handling system for an engine and having a fuel tank, comprising the steps of:

measuring a temperature change in said fuel tank while the engine is not running,

measuring a pressure change in said fuel tank while the engine is not running,

and determining whether or not a leak exists in the engine vapor handling system by comparing said temperature change with said pressure change.

6. A method of detecting a leak in a vapor handling system for an engine and having a fuel tank, comprising the steps of:

measuring a temperature increase in said fuel tank while the engine is not running,

measuring a pressure in said fuel tank while the engine is not running,

and indicating a leak if said pressure is less than a selected pressure while said temperature increase exceeds a selected increment.

7. A method of detecting a leak in a vapor handling system for an engine and having a fuel tank, comprising the steps of:

detecting a temperature decrease in said fuel tank while the engine is not running,

measuring a vacuum level in said fuel tank while the engine is not running,

and indicating a leak if a predetermined vacuum level is not attained while said temperature decrease exceeds a selected decrement.

8. A method of detecting a leak in the system as recited in claim 7, wherein the step of detecting a temperature decrease in said fuel tank, comprises the steps of:

measuring the elapsed time that the engine is on,

saving the elapsed time when the engine is turned off,

measuring a temperature of the engine,

and comparing the elapsed time with the engine temperature.

9. A diagnostic system for detecting a leak in a vapor handling system for an engine and having a fuel tank, said diagnostic system comprising:

means for determining whether the pressure in said fuel tank changes in a predetermined manner in response to changes in temperature while the engine is not running.