Control device and control method for internal combustion engine

Patent metadata

Field	Value
Publication number	US-2016348603-A1
Application number	US-201415114932-A
Country	US
Kind code	A1
Filing date	Sep 30, 2014
Priority date	Jan 30, 2014
Publication date	Dec 1, 2016
Grant date	—

Abstract

The present invention relates to a control device and a control method for a variable valve timing mechanism that changes a valve timing by adjusting a rotational speed of a motor. The control device detects a phase angle RA 1 based on an output of a crank angle sensor and an output of a cam angle sensor and calculates a change amount ΔRA of a rotational phase based on a difference between a rotation amount of a sprocket and a rotation amount of the motor. The control device stops calculating change amount ΔRA when a failure occurs in a motor rotation angle sensor. When a failure occurs in one of the crank angle sensor or the cam angle sensor, the control device stops calculating phase angle RA 1 and calculates change amount ΔRA using a normal one of the sensors and the motor rotation angle sensor.

First claim

1 .- 15 . (canceled)

16 . A control device for an internal combustion engine, the control device being to be applied to the internal combustion engine, the internal combustion engine including a variable valve timing mechanism that changes a rotational phase of a cam shaft with respect to a crank shaft by adjusting a rotational speed of a motor, a crank angle sensor that outputs a crank angle signal at a predetermined angle position of the crank shaft, a cam angle sensor that outputs a cam angle signal at a predetermined angle position of the cam shaft, and a motor rotation angle sensor that detects a rotation angle of a rotational shaft of the motor, the control device comprising:
a first rotation amount calculation unit that obtains a first rotation amount of a cam sprocket of the cam shaft per a predetermined time based on the crank angle signal; a second rotation amount calculation unit that obtains a second rotation amount of the cam sprocket per the predetermined time based on the cam angle signal; a selection unit that selects a larger one of the first rotation amount or the second rotation amount; and a phase change amount detection unit that detects a change amount of the rotational phase from the rotation amount of the cam sprocket selected by the selection unit and a rotation amount of the rotational shaft of the motor obtained based on an output of the motor rotation angle sensor.

17 . The control device for the internal combustion engine according to claim 16 , further comprising:
a first phase detection unit that detects a first detection value of the rotational phase based on the cam angle signal and the crank angle signal at each output of the can angle signal; a second phase detection unit that detects a second detection value of the rotational phase based on an integrated value of the change amount detected by the phase change amount detection unit using the first detection value as an initial value; and a control unit that controls the variable valve timing mechanism based on the second detection value.

18 . The control device for the internal combustion engine according to claim 17 , further comprising:
an update stop unit that stops updating the initial value in the second phase detection unit when an abnormality occurs in one of the crank angle sensor or the cam angle sensor.

19 . The control device for the internal combustion engine according to claim 17 , further comprising:
a reset unit that temporarily controls the variable valve timing mechanism to a default position when an abnormality in one of the crank angle sensor or the cam angle sensor is detected; and an initial value setting unit that sets the initial value in the second phase detection unit to the default position, instead of the first detection value, after the variable valve timing mechanism has been controlled to the default position by the reset unit.

20 . The control device for the internal combustion engine according to claim 19 , wherein
the default position is a position defined by a stopper.

21 . The control device for the internal combustion engine according to claim 19 , wherein
the cam shaft is an intake cam shaft, and the default position is a maximum retarded position.

22 . The control device for the internal combustion engine according to claim 17 , wherein
the second phase detection unit stops updating of the second detection value when an abnormality occurs in the motor rotation angle sensor.

23 . The control device for the internal combustion engine according to claim 17 , further comprising
a gain control unit that reduces a gain of control of the variable valve timing mechanism by the control unit so that the gain is lower than a gain in a normal state when an abnormality occurs in the motor rotation angle sensor.

24 . A control method for an internal combustion engine including a variable valve timing mechanism that changes a rotational phase of a cam shaft with respect to a crank shaft by adjusting a rotational speed of a motor, a crank angle sensor that outputs a crank angle signal at a predetermined angle position of the crank shaft, a cam angle sensor that outputs a cam angle signal at a predetermined angle position of the cam shaft, and a motor rotation angle sensor that detects a rotation angle of a rotational shaft of the motor, the method comprising the steps of:
obtaining a first rotation amount of a cam sprocket of the cam shaft per a predetermined time based on the crank angle signal; obtaining a second rotation amount of the cam sprocket per the predetermined time based on the crank angle signal; selecting a larger one of the first rotation amount or the second rotation amount; and detecting a change amount of the rotational phase from the larger one of the first rotation amount or the second rotation amount and a rotation amount of the rotational shaft of the motor obtained based on an output of the motor rotation angle sensor.

25 . The control method for the internal combustion engine according to claim 24 , further comprising the steps of:
detecting a first detection value of the rotational phase based on the cam angle signal and the crank angle signal at each output of the cam angle signal; detecting a second detection value of the rotational phase based on an integrated value of the change amount of the rotational phase using the first detection value as an initial value; and controlling the variable valve timing mechanism based on the second detection value.

26 . The control method for the internal combustion engine according to claim 25 , further comprising the step of stopping updating the initial value when an abnormality occurs in one of the crank angle sensor or the cam angle sensor.

27 . The control method for the internal combustion engine according to claim 25 , further comprising the steps of:
temporarily controlling the variable valve timing mechanism to a default position when an abnormality in one of the crank angle sensor or the cam angle sensor is detected; and setting the initial value to the default position, instead of the first detection value, after the variable valve timing mechanism has been controlled to the default position.

Assignees

• Hitachi Automotive Systems Ltd

Inventors

• Mikawa Kentaro
• Okamoto Naoki

Classifications

• F01L1/352

  using bevel or epicyclic gear · CPC title

• F01L2820/042

  Crankshafts position · CPC title

• F01L2820/032

  Electric motors · CPC title

• F01L2800/12

  Fail safe operation · CPC title

• F01L2820/041

  Camshafts position or phase sensors · CPC title