Control system for variable valve timing apparatus

Inactive Publication Date: 2011-05-05
DENSO CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Benefits of technology

[0010]In addition, after the above power supply increase control, the feedback control is carried out for the power supply to the electric motor, so that the actual changing speed of the rotational phase of the can shaft is controlled to be equal to the target changing speed. Accordingly, the changing speed of the cam shaft phase is prevented from becoming too fast and the operating sound of the VVT apparatus can be decreased.
[0011]When the cam shaft phase is changed, a load torque for compres

Problems solved by technology

However, the necessary output torque is not considered in the above mentioned prior art (JP Patent No. 4,267,635).
It may happen that the output torque of the elec

Method used

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  • Control system for variable valve timing apparatus
  • Control system for variable valve timing apparatus
  • Control system for variable valve timing apparatus

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first embodiment

[0032]Embodiments of the present invention will be explained with reference to the embodiments shown in the drawings, wherein the present invention is applied to a variable valve timing apparatus for an intake valve.

[0033]At first, an entire structure for a variable valve timing control system will be explained with reference to FIG. 1.

[0034]A driving power of an internal combustion engine 11 is transmitted by a timing chain (or a timing belt) 13 from a crank shaft 12 to a cam shaft 16 for an intake valve as well as to a cam shaft 17 for an exhaust valve via respective sprockets 14 and 15. A variable valve timing (VVT) apparatus 18 of an electrically-driven type is provided at the cam shaft 16 for the intake valve. A rotational phase (a cam shaft phase) of the cam shaft 16 with respect to the crank shaft 12 is changed by the variable valve timing (VVT) apparatus 18, so that a valve timing (a valve opening timing and / or a valve closing timing) for the intake valve (not shown) , which...

second embodiment

[0076]A second embodiment of the present invention may be applied to the VVT control system shown in FIGS. 1 and 2. Therefore, the second embodiment will be explained with reference to FIGS. 1, 2 and 6A to 8.

[0077]An optimum value of the valve timing at starting the engine depends on temperature of the engine 11 (temperature of engine cooling water). More exactly, the optimum value of the valve timing is shifted to an advancing side, as the temperature of the engine cooling water becomes lower. When the engine operation is stopped by turning off the ignition switch, and if the valve timing is not set at a proper value for a next engine starting operation (wherein the proper value depends on the temperature of the engine cooling water at re-starting the engine operation), it may happen that the engine operation may not be smoothly started.

[0078]According to the second embodiment, the valve timing is changed not only during the engine is operated but also when the engine operation is ...

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Abstract

When a cam shaft phase is changed during engine operation is stopped, a power supply increase control to an electric motor is carried out, according to which a power-supply duty ratio to the electric motor is increased to a predetermined power increase value which is necessary for moving a VVT apparatus during the stop of the engine operation. Then, the power-supply duty ratio is feedback controlled so that an actual changing speed of the cam shaft phase becomes equal to a target changing speed. As a result, the cam shaft phase can be surely changed and operating sound can be reduced by preventing the changing speed of the cam shaft phase from becoming too fast.

Description

CROSS REFERENCE TO RELATED APPLICATION[0001]This application is based on Japanese Patent Application No. 2009-251708 filed on Nov. 2, 2009 and No. 2010-000944 filed on Jan. 6, 2010, the disclosures of which are incorporated herein by reference.FIELD OF THE INVENTION[0002]The present invention relates to a variable valve timing apparatus of an electrically-driven type, more particularly to a control system for such variable valve timing apparatus, according to which a rotational phase of a cam shaft with respect to a crank shaft of an internal combustion engine is changed by an electric motor in order to change valve timing.BACKGROUND OF THE INVENTION[0003]Conventionally, a variable valve timing apparatus is known in the art, which is mounted in an internal combustion engine for a vehicle, and according to which a valve timing (a valve opening and / or valve closing timing) for an intake valve and / or an exhaust valve is changed, in order to increase engine output power, to improve fuel...

Claims

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Application Information

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IPC IPC(8): F01L1/34
CPCF01L1/344F01L1/022F01L1/024F01L1/352F01L2001/0537F01L2800/01F01L2800/03
Inventor HIRATA, YASUO
Owner DENSO CORP
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