Method and apparatus for controlling CVVT of an engine

• US 20040020452A1
• Filed: 04/10/2003
• Published: 02/05/2004
• Est. Priority Date: 07/31/2002
• Status: Active Grant

• Current Assignee: Hyundai Motor Company (Hyundai Motor Group)
• Original Assignee: Hyundai Motor Company (Hyundai Motor Group)
• Inventors: Park, Yong-Jung
• Granted Patent: US 7,007,645 B2
• Time in Patent Office: Days
• US Class Current: 123/90.15
• CPC Class Codes: F01L 1/34 characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift

Abstract

Controlling of a CVVT can be improved by controlling the CVVT based on an estimated oil temperature, the estimated oil temperature being calculated on the basis of a coolant temperature at starting of the engine and a period of time that has elapsed after the starting of the engine.

Claims

1. A method for controlling CVVT of a vehicle engine, comprising:

calculating an estimated oil temperature on the basis of a coolant temperature at starting of the engine and a period of time that has elapsed after the starting of the engine;

storing the estimated oil temperature in a memory; and

controlling the CVVT based on the estimated oil temperature.

2. The method of claim 1, wherein the calculating of the estimated oil temperature comprises:

calculating a primitively estimated oil temperature on the basis of the coolant temperature at starting of the engine and the period of time that has elapsed after the starting of the engine; and

modifying the primitively estimated oil temperature.

3. The method of claim 2, wherein the modifying of the primitively estimated oil temperature modifies it by multiplying it by a weight factor if a vehicle speed is greater than a predetermined vehicle speed, an engine speed is greater than a predetermined engine speed, and a throttle opening is greater than a predetermined opening.

4. The method of claim 2, wherein the modifying of the primitively estimated oil temperature modifies it by multiplying it by a weight factor if a vehicle speed is greater than a predetermined vehicle speed, and a throttle opening is greater than a predetermined opening.

5. The method of claim 2, wherein the modifying of the primitively estimated oil temperature modifies it by multiplying it by a weight factor if an intake-air temperature is less than a predetermined temperature.

6. The method of claim 2, wherein the modifying of the primitively estimated oil temperature modifies it by multiplying it by a weight factor if a cooling fan of the engine operates.

7. The method of claim 1, further comprising determining if the engine has been cold-started,

wherein the calculating of the estimated oil temperature is executed if the engine has been cold-started.

8. The method of claim 7, further comprising:

detecting a current coolant temperature if the engine has not been cold-started; and

determining if a difference between the current coolant temperature and the estimated oil temperature stored in the memory is less than a predetermined difference, wherein the controlling of the CVVT based on the estimated oil temperature is executed when the difference between the current coolant temperature and the estimated oil temperature stored in the memory is less than the predetermined difference.

9. The method of claim 7, further comprising:

detecting a current coolant temperature if the engine has not been cold-started; and

determining if a difference between the current coolant temperature and the estimated oil temperature stored in the memory is less than a predetermined difference,

wherein the calculating of the estimated oil temperature is executed when the difference between the current coolant temperature and the estimated oil temperature stored in the memory is not less than the predetermined difference.

13. The apparatus of claim 11, further comprising:

a vehicle speed detector for detecting a vehicle speed; and

a throttle opening detector for detecting a throttle opening of the engine,

wherein the modifying of the primitively estimated oil temperature modifies it by multiplying it by a weight factor if the vehicle speed is greater than a predetermined vehicle speed, and the throttle opening is greater than a predetermined opening.

10. An apparatus for controlling CVVT of a vehicle engine, comprising:

a coolant temperature detector for detecting coolant temperature of the engine; and

an electronic control unit that is activated by predetermined software, the electronic control unit being equipped with a timer and a memory,

wherein the predetermined software comprises instructions for;

calculating an estimated oil temperature on the basis of a coolant temperature at starting of the engine and a period of time that has elapsed after the starting of the engine;

storing the estimated oil temperature in the memory; and

controlling the CVVT based on the estimated oil temperature.

11. The apparatus of claim 10, wherein the calculating of the estimated oil temperature comprises:

calculating a primitively estimated oil temperature on the basis of the coolant temperature at starting of the engine and the period of time that has elapsed after the starting of the engine; and

modifying the primitively estimated oil temperature.

12. The apparatus of claim 11, further comprising:

a vehicle speed detector for detecting a vehicle speed;

an engine speed detector for detecting revolution speed of the engine; and

a throttle opening detector for detecting a throttle opening of the engine,

wherein the modifying of the primitively estimated oil temperature modifies it by multiplying it by a weight factor if the vehicle speed is greater than a predetermined vehicle speed, the engine speed is greater than a predetermined engine speed, and the throttle opening is greater than a predetermined opening.

14. The apparatus of claim 11, further comprising an intake-air temperature detector for detecting intake-air temperature of the engine,

wherein the modifying of the primitively estimated oil temperature modifies it by multiplying it by a weight factor if the intake-air temperature is less than a predetermined temperature.

15. The apparatus of claim 11, further comprising a fan switch for controlling operation of a cooling fan of the engine,

wherein the modifying of the primitively estimated oil temperature modifies it by multiplying it the by a weight factor if the cooling fan of the engine operates.

16. The apparatus of claim 10, wherein the predetermined software further comprises instructions for determining if the engine has been cold-started, and the calculating of the estimated oil temperature is executed if the engine has been cold-started.

17. The apparatus of claim 16, wherein the predetermined software further comprises instructions for:

detecting a current coolant temperature if the engine has not been cold-started; and

determining if a difference between the current coolant temperature and the estimated oil temperature stored in the memory is less than a predetermined difference, and

wherein the controlling of the CVVT based on the estimated oil temperature is executed when the difference between the current coolant temperature and the estimated oil temperature stored in the memory is less than the predetermined difference.

18. The apparatus of claim 16, wherein the predetermined software further comprises instructions for:

detecting a current coolant temperature if the engine has not been cold-started; and

determining if a difference between the current coolant temperature and the estimated oil temperature stored in the memory is less than a predetermined difference, and

wherein the calculating of the estimated oil temperature is executed when the difference between the current coolant temperature and the estimated oil temperature stored in the memory is not less than the predetermined difference.

19. A method for controlling valve timing of an engine, comprising:

measuring coolant temperature at starting of an engine;

measuring elapsed time following starting of the engine;

calculating an estimated oil temperature based on said coolant temperature at starting of the engine and said elapsed time;

storing said estimated oil temperature in an memory; and

controlling a CVVT based on said estimated oil temperature.

20. An apparatus for controlling valve timing of an engine, comprising:

a detection unit configured for at least detecting a temperature of coolant of an engine at starting of the engine;

an electronic control unit comprising;

a timer configured to calculate an amount of elapsed time post starting;

a memory configured to store data from said detection unit and said timer;

preprogrammed software configured to;

estimate oil temperature of the engine based on the detected coolant temperature at starting of the engine by said detection unit, the amount of elapsed time post starting, and data stored in the memory; and

control a CVVT of the engine based on said estimated oil temperature.