Engine crankcase gas blow-by sensor

• US 6,575,022 B1
• Filed: 06/24/1998
• Issued: 06/10/2003
• Est. Priority Date: 11/25/1995
• Status: Expired due to Fees

• Current Assignee: Cummins Incorporated
• Original Assignee: Cummins Incorporated
• Inventors: Schneider, Matthew L., Schuppe, Alfred, Bhagwat, Abhay P., Kuhns, George M.
• Primary Examiner(s): OEN, WILLIAM L
• Application Number:
  US09/105,124
• Time in Patent Office: 1,812 Days
• Field of Search: 731/16, 731/172, 731/173, 731/181, 731/182, 738/616.3
• US Class Current: 73/114.01
• CPC Class Codes: F01M 13/00 Crankcase ventilating or breathing
• CPC Class Codes: F01M 2013/0083 Crankcase pressure
• CPC Class Codes: G01F 1/44 Venturi tubes
• CPC Class Codes: G01M 15/09 by monitoring pressure in fluid ducts, e.g. in lubrication or cooling parts

Abstract

An engine crankcase gas blow-by sensor. In a closed crankcase ventilation system, crankcase gases are caused to flow through a venturi which includes high pressure and low pressure taps. The high and low pressure taps are coupled to a differential pressure transducer which produces an output that is proportional to the volumetric flow of crankcase gases through the venturi. The use of a venturi in conjunction with a differential pressure sensor offers a low resistance path for the flow of crankcase gases and allows continuous monitoring of blow-by without exceeding the operating pressure limitations of various oil seals. Such a sensor is particularly suited for closed crankcase ventilation (ccv) systems, as it doesn'"'"'t require venting of crankcase gases to the atmosphere, but works well in open crankcase ventilation systems also.

Claims

1. An internal combustion engine, comprising:

at least one cylinder;

at least one piston slidingly disposed within the at least one cylinder in order to define a combustion chamber above the piston;

an air intake system operable to supply air to the combustion chamber;

a crankcase coupled to the at least one cylinder, wherein an interior of the crankcase is in fluid communication with an interior of the at least one cylinder below the at least one piston, wherein combustion gases which blow-by the at least one piston may enter the crankcase;

a venturi having an inlet port and an outlet port, wherein the inlet port is coupled to the crankcase interior and the outlet port is coupled to the air intake system such that gas within the crankcase may flow through the venturi;

a high pressure tap extending from an exterior of the venturi to an interior of the venturi;

a low pressure tap extending from the venturi exterior to the venturi interior; and

a sensor coupled to the venturi and operative to measure a differential pressure between the high pressure tap and the low pressure tap.

2. The internal combustion engine of claim 1, wherein the high pressure tap extends from the venturi exterior to an interior of an inlet bore of the venturi.

3. The internal combustion engine of claim 1, wherein the low pressure tap extends from the venturi exterior to an interior of a venturi throat of the venturi.

4. The internal combustion engine of claim 1, wherein the sensor comprises a wet-dry differential pressure sensor.

5. The internal combustion engine of claim 1, wherein the sensor comprises a variable capacitive on ceramic pressure sensor.

6. The internal combustion engine of claim 1, wherein the venturi is mounted substantially vertically in order to allow gas to run out of the venturi.

7. An engine crankcase gas blow-by sensor, comprising:

an engine crankcase operative to contain blow-by gases;

an air intake system;

a venturi having an inlet port and an outlet port, wherein the inlet port is coupled to an interior of the engine crankcase and the outlet port is coupled to the air intake system such that gas within the crankcase may flow through the venturi;

a high pressure tap extending from an exterior of the venturi to an interior of the venturi;

a low pressure tap extending from the venturi exterior to the venturi interior; and

a sensor coupled to the venturi and operative to measure a differential pressure between the high pressure tap and the low pressure tap.

8. The engine crankcase gas blow-by sensor of claim 7, wherein the high pressure tap extends from the venturi exterior to an interior of an inlet bore of the venturi.

9. The engine crankcase gas blow-by sensor of claim 7, wherein the low pressure tap extends from the venturi exterior to an interior of a venturi throat of the venturi.

10. The engine crankcase gas blow-by sensor of claim 7, wherein the sensor comprises a wet-dry differential pressure sensor.

11. The engine crankcase gas blow-by sensor of claim 7, wherein the sensor comprises a variable capacitive on ceramic pressure sensor.

12. Tie engine crankcase gas blow-by sensor of claim 7, wherein the venturi is mounted substantially vertically in order to allow gas to run out of the venturi.

13. A method of evaluating performance of an internal combustion engine, comprising the steps of:

(a) routing at least a portion of blow-by gases within a crankcase of the engine through a venturi having a high pressure tap and a low pressure tap;

(b) measuring a pressure differential between the high pressure tap and the low pressure tap; and

(c) outputting a signal that is proportional to the measured pressure differential.

14. The method of claim 13, wherein step (b) is performed by a wet-dry differential pressure sensor.

15. The method of claim 13, wherein step (b) is performed by a variable capacitive on ceramic pressure sensor.

16. The method of claim 13, wherein the signal is a voltage signal.