Automatic engine oil change indicator system

• US 4,847,768 A
• Filed: 08/29/1988
• Issued: 07/11/1989
• Est. Priority Date: 08/29/1988
• Status: Expired due to Term

• Current Assignee: General Motors Corporation (General Motors Company)
• Original Assignee: General Motors Corporation (General Motors Company)
• Inventors: Schwartz, Ellen S., Keersmaekers, John D., Wallo, Gary J., Traylor, Christine M., Smolenski, Donald J.
• Primary Examiner(s): Chin, Gary
• Application Number:
  US07/237,762
• Time in Patent Office: 316 Days
• Field of Search: 364/424.03, 364/424.04, 364/550, 364/551.01, 340/52 R, 340/52 D, 340/52 F, 73/117.3, 73/64, 123/196 R, 123/196 S
• US Class Current: 701/30
• CPC Class Codes: B60Q 9/00 Arrangement or adaptation of signal devices not provided for in one of main groups B60Q1/00 - B60Q7/00 , e.g. haptic signalling
• CPC Class Codes: B60R 16/0234 related to maintenance or repairing of vehicles
• CPC Class Codes: F01M 11/10 Indicating devices; Other safety devices
• CPC Class Codes: F01M 2011/14 for indicating the necessity to change the oil
• CPC Class Codes: F01M 2011/1473 by considering temperature
• CPC Class Codes: F16N 2260/18 necessity of changing oil
• CPC Class Codes: G07C 5/006 Indicating maintenance

Abstract

An apparatus and method is disclosed for indicating useful life of motor vehicle angine oil during engine operation based on engine oil temperature without direct measurement thereof. Following the initiation of engine operation, engine oil temperature is calculated from a warmup equation until calculated engine oil temperature exceeds a warmup reference, whereupon it is calculated from an equilibrium equation, both of which equations being linear combinations of engine operating parameters other than engine oil temperature itself. The warmup equation includes a constant term, a reference temperature term fixed at the begining of engine operation and a term increasing proportionally with the number of engine cylinder firings. The equilibrium equation includes a constant term, an engine temperature term and a term proportional to engine speed and may also include a term proportional to an engine cooling factor.

Claims

1. In a motor vehicle having an engine containing lubricating engine oil which has a useful life that varies in accordance with engine operating conditions and apparatus for determining the remaining useful life of the engine oil in engine operation from the engine oil temperature, apparatus for determining the engine oil temperature without direct measurement thereof comprising, in combination:

means for storing a datum having a first value indicating that the engine oil temperature is in a warming range and a second value indicating that the engine oil temperature is in an equilibrium range, the stored datum being set to the first value at the beginning of engine operation;

means responsive to the first value of the stored datum to calculate the engine oil temperature T_o according to a warmup equation T_o =k₁ +k₂ T_r +k₃ F_f, wherein T_r is a reference temperature indicative of engine oil temperature at the beginning of engine operation, F_f is a firing factor proportional to the number of combustion firings since the beginning of engine operation, and k₁, k₂ and k₃ are constants;

means responsive to the second value of the stored datum to calculate the engine oil temperature T_o according to an equilibrium equation T_o =k₄ +k₅ T_e +k₆ S_e, wherein T_e is an engine temperature indicative of engine oil temperature, S_e is engine rotational speed, and k₄, k₅ and k₆ are constants;

means for storing the calculated engine oil temperature T_o for use by the apparatus for determining the remaining useful life of the engine oil; and

means for setting the stored datum to its second value when the calculated engine oil temperature T_o exceeds a predetermined warmup temperature.

2. The apparatus of claim 1 in which the reference temperature T_r is derived from an initial engine coolant temperature T_c at the beginning of engine operation and the engine temperature T_e is the engine coolant temperature.

3. The apparatus of claim 1 in which an additional term k₇ F_c is added to the equilibrium equation, wherein F_c is an engine cooling factor and k₇ is a constant.

4. The apparatus of claim 3 in which the engine cooling factor F_c is ambient air temperature.

5. The apparatus of claim 3 in which the engine cooling factor F_c is vehicle speed.

6. The apparatus of claim 3 in which the engine cooling factor F_c is a linear combination of ambient air temperature and vehicle speed.

7. The apparatus of claim 1 in which the value of the reference temperature T_r in the warmup equation is corrected, from a sensed value of the reference temperature T_r, when engine operation is initiated less than a predetermined short time off duration after the last preceding cessation of engine operation, so as to correct for a difference between the reference temperature and actual engine oil. temperature during the predetermined short time off duration after engine operation is stopped.

8. The apparatus of claim 2 further comprising:

means for sensing an initial engine coolant temperature T_c at the beginning of engine operation;

means for deriving the reference temperature T_r by decreasing the initial engine coolant temperature T_c when an off time duration D_t between the initiation of the present engine operation and the cessation of the last preceding engine operation is less than a predetermined short time off duration, the reference temperature T_r otherwise being equal to the initial engine coolant temperature T_c.

9. The apparatus of claim 8 in which, when the off time duration D_t is less than the predetermined short time off duration, the means for deriving the reference temperature T_r senses and stores the off time duration D_t and derives the reference temperature T_r according to the equation T_r =c₁ +c₂ T_c +c₃ D_t, wherein c₁ is a negative constant and c₂ and c₃ are positive constants.

10. In a motor vehicle having an engine containing lubricating engine oil which has a useful life that varies in accordance with engine operating conditions and apparatus for determining the remaining useful life of the engine oil in engine operation from engine oil temperature, a method for determining the engine oil temperature without direct measurement thereof comprising the steps of:

storing a datum having a first value indicating that the engine oil temperature is in a warming range and a second value indicating that the engine oil temperature is in an equilibrium range;

setting the stored datum to the first value at the beginning of engine operation;

calculating the engine oil temperature T_o, when the stored datum has the first value, according to a warmup equation T_o =k₁ +k₂ T_r +k₃ F_f, wherein T_r is a reference temperature indicative of engine oil temperature at the beginning of engine operation, F_f is a firing factor proportional to the number of combustion firings since the beginning of engine operation, and k₁, k₂ and k₃ are constants;

calculating the engine oil temperature T_o, when the stored datum has the second value, according to an equilibrium equation T_o =k₄ +k₅ T_e +k₆ S_e, wherein T_e is an engine temperature, S_e is engine rotational speed, and k₄, k₅ and k₆ are constants;

storing the calculated engine oil temperature T_o for use by the apparatus for determining the remaining useful life of the lubricating oil; and

setting the stored datum to its second value when the calculated engine oil temperature T_o exceeds a predetermined warmup temperature.

11. The method of claim 10 in which an additional term k₇ F_c is added to the equilibrium equation, wherein F_c is an engine cooling factor and k₇ is a constant.

12. The method of claim 11 in which the engine cooling factor F_c is ambient air temperature.

13. The method of claim 11 in which the engine cooling factor F_c is vehicle speed.

14. The method of claim 11 in which the engine cooling factor F_c is a linear combination of ambient air temperature and vehicle speed.