Control device and control method for variable valve timing mechanism

Patent metadata

Field	Value
Publication number	US-11230988-B2
Application number	US-201917251637-A
Country	US
Kind code	B2
Filing date	Feb 20, 2019
Priority date	Jun 13, 2018
Publication date	Jan 25, 2022
Grant date	Jan 25, 2022

Abstract

A control device and a control method for variable valve timing mechanism according to the present invention obtains a first measurement of a rotational phase based on a rotational angle of the motor, obtains a second measurement of the rotational phase based on a relative relationship between a rotational angle of the crankshaft and a rotational angle of the camshaft, calibrates the first measurement based on the second measurement, obtains a derivative term proportional to a rate of change in a deviation between the first measurement and a target value, reduces change in derivative term when calibrating the first measurement based on the second measurement, and controls the motor based on a manipulated variable including the derivative term.

First claim

The invention claimed is:

1. A control device of a variable valve timing mechanism that makes a rotational phase of a camshaft variable relative to a crankshaft of an internal combustion engine by adjusting rotation of a motor, the control device being configured to:
obtain information on a rotational angle of the motor, information on a rotational angle of the crankshaft, and information on a rotational angle of the camshaft;
obtain a first measurement of the rotational phase based on the rotational angle of the motor;
obtain a second measurement of the rotational phase based on a relative relationship between the rotational angle of the crankshaft and the rotational angle of the camshaft;
calibrate the first measurement based on the second measurement;
obtain a derivative term proportional to a rate of change in a deviation between the first measurement and a target value of the rotational phase;
reduce change in derivative term when calibrating the first measurement based on the second measurement;
obtain a manipulated variable of the motor based on the derivative term; and
control the motor based on the manipulated variable.

2. The control device of the variable valve timing mechanism according to claim 1 , wherein the control device is configured to reduce change in the derivative term so that an amount of change between a derivative term obtained from the first measurement and a derivative value obtained from the calibrated first measurement becomes less than a predetermined value.

3. The control device of the variable valve timing mechanism according to claim 1 , wherein the control device is configured to reduce change in the derivative term by obtaining the manipulated variable, using a derivative term obtained from the first measurement.

4. The control device of the variable valve timing mechanism according to claim 1 , wherein the control device is configured to reduce a calibration frequency of the first measurement as a rotational speed of the internal combustion engine increases.

5. A control method for a variable valve timing mechanism that makes a rotational phase of a camshaft variable relative to a crankshaft of an internal combustion engine by adjusting rotation of a motor, the control method comprising the steps of:
obtaining a first measurement of the rotational phase based on a rotational angle of the motor;
obtaining a second measurement of the rotational phase based on a relative relationship between a rotational angle of the crankshaft and a rotational angle of the camshaft;
calibrating the first measurement based on the second measurement;
obtaining a derivative term proportional to a rate of change in a deviation between the first measurement and a target value of the rotational phase;
reducing change in the derivative term when calibrating the first measurement based on the second measurement; and
controlling the motor based on a manipulated variable including the derivative term.

Assignees

• Hitachi Automotive Systems Ltd
• Hitachi Astemo Ltd

Inventors

• Jitsuishi Makoto
• Matsuo Nobuhiko

Classifications

• F02D2200/101

  Engine speed · CPC title

• F02D41/2464

  Characteristics of actuators · CPC title

• F01L2820/041

  Camshafts position or phase sensors · CPC title

• F01L2820/04

  Sensors · CPC title

• F01L2001/0537

  Double overhead camshafts [DOHC] · CPC title