Multi-Cylinder Engine Cylinder Deactivation Pumping Loss Reduction
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Solution Overview
Problem
During cylinder deactivation in multi-cylinder engines, the rapid reduction in combustion chamber pressure due to closed intake and exhaust valves leads to resistance against piston movement, resulting in pumping loss, which is not adequately addressed by existing variable valve operating mechanisms.
Innovation Solution
A control device that manages cylinder deactivation by stopping fuel injection and prohibiting intake valve lift while opening at least one exhaust valve during piston downward movement, communicating the combustion chamber with the exhaust port to maintain internal pressure and reduce pumping loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If both intake and exhaust valves are closed during cylinder deactivation, then fuel injection can be stopped to reduce fuel consumption, but combustion chamber pressure rapidly reduces causing resistance against piston movement and pumping loss
Solution Approach 1:
The exhaust valve control is segmented into two independent systems: a variable valve operating mechanism for one exhaust valve that can be controlled independently during cylinder deactivation, and a fixed valve operating mechanism for the other exhaust valve. This segmentation allows selective opening of at least one exhaust valve during downward piston movement to maintain combustion chamber pressure and reduce pumping loss, while keeping the system manageable through division of control functions.
2Loss of energy
If at least one exhaust valve is opened during downward piston movement in deactivated cylinder, then pumping loss is reduced by maintaining internal pressure, but valve control mechanism complexity increases
Solution Approach 1:
The valve control system merges two different control approaches: a variable valve operating mechanism capable of timing and lift control, and a fixed valve operating mechanism providing constant timing and lift. By combining these two mechanisms for the exhaust valves, the system achieves the ability to reduce pumping loss through selective valve opening while utilizing the simplicity of fixed mechanism for one valve and the flexibility of variable mechanism for the other.
Solution Approach 2:
The variable valve operating mechanism serves multiple functions: it controls the exhaust valve during normal operation and provides additional control capability during cylinder deactivation to maintain combustion chamber pressure. This multi-functionality allows a single mechanism type to handle both standard valve operation and the special requirements of deactivation mode, reducing the need for entirely separate control systems.
Data Source
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AI summary
Disclosed is a control device for a multi-cylinder engine having a combustion chamber 19 to which an intake port 16 and an exhaust port 17 are connected. The control device comprises: an intake-side variable valve operating mechanism 71 for controlling a lift timing of two intake valves 21a, 21b of the intake port 16; an exhaust-side variable valve operating mechanism 72 for controlling a lift timing of an exhaust valve 22a; and an exhaust-side valve operating mechanism 73 for driving an exhaust valve 22b at a fixed timing. The control device is operable, when executing cylinder deactivation in a low engine load and low engine speed operating range, to cause the exhaust-side variable valve operating mechanism 72 to open the exhaust valve 22a during downward movement of a piston 14 in a cylinder 18 being subjected to the cylinder deactivation.