Engine oil contamination sensor

• US 6,590,402 B2
• Filed: 10/02/2001
• Issued: 07/08/2003
• Est. Priority Date: 10/02/2001
• Status: Expired due to Fees

• Current Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Lin, Yingjie, Wang, Su-Chee Simon
• Primary Examiner(s): Oda, Christine
• Assistant Examiner(s): HAMDAN, WASSEEM H
• Application Number:
  US09/969,222
• Publication Number:
  US 20030062910A1
• Time in Patent Office: 644 Days
• Field of Search: 324/698, 324/663, 324/441, 324/668, 73/530.5, 701/30, 123/196.5, 340/522, 340/603, 340/604, 340/631
• US Class Current: 324/698
• CPC Class Codes: G01N 27/06 of a liquid involving electrolysis G01N27/26
• CPC Class Codes: G01N 33/2888 Lubricating oil characteristics, e.g. deterioration lubricating properties G01N33/30

Abstract

An engine oil contamination sensor includes a first sensing electrode and a second sensing electrode. A sensing area is established between the electrodes. The sensor is oriented in an oil pan such that the sensing are is completely submerged in engine oil. A microprocessor is connected to the sensing electrodes and includes a program for determining whether antifreeze is dispersed in the engine oil.

Claims

1. A method for determining dispersed antifreeze contamination of oil within an engine using an oil contamination sensor, wherein the oil has a relatively slow resistance change over the life of the oil, comprising the acts of:

allowing the oil to pass through a temperature gradient;

measuring the output voltage of the sensor;

at least partially based on the output voltage of the sensor, determining whether antifreeze is being dispersed in the oil

determining when the oil temperature is within a middle temperature range;

determining a threshold voltage value, Vth;

determining a first difference value, DV₁;

determining a second difference value, DV₂;

determining a third difference value, DV₃;

comparing the difference values, DV₁, DV₂, DV₃, to the threshold voltage value, Vth; and

at least partially based on the comparing act, determining whether antifreeze is being dispersed in the engine oil.

2. The method of claim 1, where:

V_th=A*Vref, where A is a percentage value and V_ref=(V<sub>n−

5</sub>+V<sub>n−

4</sub>+V<sub>n−

3</sub>)/3, where V_ref=a starting reference voltage, V<sub>n−

5</sub>=a fifth previous voltage value, V<sub>n−

4</sub>=a fourth previous voltage value, V<sub>n−

3</sub>=a third previous voltage value; and

DV₁=abs (V<sub>n−

2</sub>−

V_ref), DV₂=abs (V<sub>n−

1</sub>−

V_ref), DV₃=abs (V_n−

V_ref), where V<sub>n−

2</sub>=a second previous voltage value, V<sub>n−

1</sub>=a first previous voltage value, and V_n=a current voltage value.

3. The method of claim 2, where A is from ten percent to fifteen percent (10%-15%).

4. The method of claim 3, further comprising the acts of:

determining whether any two of the three difference values, DV₁, DV₂, DV₃, are greater than the threshold value, Vth; and

at least partially based on the determining act, indicating whether antifreeze is dispersed in the engine oil.

5. The method of claim 1, wherein the middle temperature range is from forty degrees Celsius to sixty degrees Celsius (40°

-60°

).

6. The method of claim 1, where the oil has a relatively rapid resistance change over the life of the oil, and the method further comprises the acts of:

measuring a series of output voltages from the sensor at a low temperature range;

comparing a present output voltage to an immediately previous voltage value; and

at least partially based on the comparing act, determining whether antifreeze is being dispersed in the engine oil.

7. The method of claim 6, wherein the low temperature range is from thirty degrees Celsius to forty degrees Celsius (30°

C.-40°

C.).

8. An oil contamination sensor, comprising:

a first sensing electrode;

a second sensing electrode;

a sensing area established between the electrodes, the sensing area being submerged in an engine oil having a relatively slow resistance change over the life of the oil;

a microprocessor connected to the sensing electrodes, the microprocessor including a program for determining whether antifreeze is dispersed in the engine oil, the program comprising;

logic means for measuring the output voltage of the sensor, while the engine oil is passing through a temperature gradient;

logic means for determining whether antifreeze is being dispersed in the oil at least partially based on the output voltage of the sensor;

logic means for determining when the oil temperature is within a predetermined middle temperature range;

logic means for determining a threshold voltage value, Vth;

logic means for determining a first difference value, DV₁;

logic means for determining a second difference value, DV₂;

logic means for determining a third difference value, DV₃;

logic means for comparing the difference values, DV₁, DV₂, DV₃, to the threshold voltage value, Vth; and

logic means for determining whether antifreeze is being dispersed in the engine oil at least partially based on the comparing act.

9. The sensor of claim 8, where:

V_th=A*V_ref, where A is a percentage value and V_ref=(V<sub>n−

5</sub>+V<sub>n−

4</sub>+V<sub>n−

3</sub>)/3, where V_ref=a starting reference voltage, V<sub>n−

5</sub>=a fifth previous voltage value, V<sub>n−

4</sub>=a fourth previous voltage value, V<sub>n−

3</sub>=a third previous voltage value; and

DV₁=abs (V<sub>n−

2</sub>−

V_ref), DV₂=abs (V<sub>n−

1</sub>−

V_ref), DV₃ =abs (V_n−

V_ref), where V<sub>n−

2</sub>=a second previous voltage value, V<sub>n−

1</sub>=a first previous voltage value, and V_n=a current voltage value.

10. The sensor of claim 9, where A is from ten percent to fifteen percent (10%-15%).

11. The sensor of claim 10, wherein the program further comprises:

logic means for determining whether any two of the three difference values, DV₁, DV₂, DV₃, are greater than the threshold value, Vth; and

logic means for indicating that antifreeze is dispersed in the engine oil at least partially based on the determining act.

12. The sensor of claim 8, wherein the middle temperature range is from forty degrees Celsius to sixty degrees Celsius (40°

-60°

).

13. The sensor of claim 8, further comprising:

an output device connected to the microprocessor, the output device receiving a signal from the microprocessor when antifreeze is being dispersed in engine oil.

14. The sensor of claim 8, further comprising:

a spacer disposed between the electrodes.

15. The sensor of claim 8, wherein the sensor is placed in an oil having a relatively rapid resistance change over the life of the oil, and the program further comprises:

logic means for measuring a series of output voltages from the sensor, while the oil is in a low temperature range;

logic means for comparing a present output voltage to an immediately previous voltage value; and

logic means for determining whether antifreeze is being dispersed in the engine oil at least partially based on the comparing act.

16. The sensor of claim 15, wherein the low temperature range is from thirty degrees Celsius to forty degrees Celsius (30°

C.-40°

C.).