Cam-switching device and method of controlling cam-switching device
AssigneeIsuzu Motors Limited
InventorHiroshi Tsunoda
Life of this patent
Estimating the term…
Abstract
A cam-switching device switches between first and second cams provided so as to correspond to intake exhaust valves of an engine. In a case of switching from the first cam to the second cam, a cylinder resting unit stops the opening and closing operations of the intake and exhaust valves in the same combustion cycle, and a cam shaft moving unit starts sliding the cam shaft in a first cam angle range. In a case of switching from the second cam to the first cam, the cylinder resting unit stops the opening and closing operations of the intake and exhaust valves in the same combustion cycle, and the cam shaft moving unit starts sliding the cam shaft in a second cam angle range.
Claims4
A cam-switching device that selectively switches between a first cam and a second cam to make valve characteristics of intake and exhaust valves of an engine variable,
- the first cam and the second cam being provided corresponding to each of the intake and exhaust valves and having different cam profiles,
- each of the cam profiles being determined such that a first cam angle range where a valve lift amount of the first cam is greater than a valve lift amount of the second cam and a second cam angle range where a valve lift amount of the second cam is greater than a valve lift amount of the first cam are formed, and
- the cam-switching device comprising:
- a cam shaft configured to rotate in conjunction with a crank shaft of the engine and provided such that the first cam and the second cam rotate together;
- a cam shaft moving unit comprising an intake-side slide groove and an intake-side electromagnetic solenoid, and an exhaust-side slide groove and an exhaust-side electromagnetic solenoid, configured to slide the cam shaft in an axial direction to selectively switch between the first cam and the second cam;
- a cylinder resting unit comprising a rocker arm, a bracket, a hydraulic tappet, a needle, and a third electromagnetic solenoid, configured to stop opening and closing operations of the intake and exhaust valves to deactivate a cylinder;
- and
- an electronic control unit (ECU) configured to control the cylinder resting unit to stop the opening and closing operations of the intake and exhaust valves in a same combustion cycle and control the cam shaft moving unit to start sliding the cam shaft in the first cam angle range in a case of switching from the first cam to the second cam, and to control the cylinder resting unit to stop the opening and closing operations of the intake and exhaust valves in the same combustion cycle and control the cam shaft moving unit to start sliding the cam shaft in the second cam angle range in a case of switching from the second cam to the first cam.
A method of controlling a cam-switching device including a first cam and a second cam provided to each of intake and exhaust valves of an engine and having different cam profiles, each of the cam profiles being determined such that a first cam angle range where a valve lift amount of the first cam is greater than a valve lift amount of the second cam and a second cam angle range where a valve lift amount of the second cam is greater than a valve lift amount of the first cam are formed, a cam shaft configured to rotate in conjunction with a crank shaft of the engine and provided such that the first cam and the second cam are rotatable together, a cam shaft moving unit comprising an intake-side slide groove and an intake-side electromagnetic solenoid, and an exhaust-side slide groove and an exhaust-side electromagnetic solenoid, configured to slide the cam shaft in an axial direction to selectively switch between the first cam and the second cam, and a cylinder resting unit comprising a rocker arm, a bracket, a hydraulic tappet, a needle, and an electromagnetic solenoid, configured to stop opening and closing operations of the intake and exhaust valves, the method comprising:
- stopping the opening and closing operations of the intake and exhaust valves in a same combustion cycle and start sliding the cam shaft in the first cam angle range in a case of switching from the first cam to the second cam;
- and
- stopping the opening and closing operations of the intake and exhaust valves in a same combustion cycle and start sliding the cam shaft in the second cam angle range in a case of switching from the second cam to the first cam.
Dependencies are inferred from the claim text.