Sliding Camshaft Actuation for Cylinder Deactivation
Solution Overview
Problem
Internal combustion engines with four cylinders face inefficiencies in load-dependent operation due to limitations in valve control, particularly in reducing fuel consumption and pollutant emissions under partial load conditions.
Innovation Solution
The engine employs a camshaft system with actuating cams of different geometries for each intake valve, allowing for the activation of full-stroke, partial-stroke, and zero-stroke cams to deactivate specific intake valves, enabling the engine to operate efficiently by reducing airflow to inactive cylinders and increasing swirl in active cylinders, thereby improving fuel efficiency and reducing emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a camshaft system with multiple actuating cams of different geometries is used for each intake valve, then the engine can selectively deactivate cylinders and improve fuel efficiency under partial load conditions, but the device complexity and manufacturing cost increase
Solution Approach 1:
The valve train system employs dynamically switchable cam geometries where the sliding mechanism allows selection between first and second cam profiles based on operating conditions. This dynamic adaptability enables the engine to optimize valve lift characteristics for different load scenarios, improving fuel efficiency without requiring completely separate valve train systems.
Solution Approach 2:
Each intake valve is equipped with a universal cam engagement system that can accommodate multiple cam geometries (first cam with first geometry, second cam with second geometry) through the sliding mechanism. This multi-functional design allows a single valve train component to perform multiple functions: full valve lift operation, partial valve lift operation, and valve deactivation, thereby reducing the need for separate dedicated systems.
2Loss of energy
If multiple actuating cams with different geometries are assigned to each intake valve, then partial load efficiency improves, but the number of valve train adjustment devices increases
Solution Approach 1:
The sliding mechanism integrates the function of selecting between multiple cam geometries into a single mechanical component that works in conjunction with each intake valve's actuating cams. By merging the cam selection function into this unified sliding mechanism rather than requiring separate adjustment devices for each cam, the system reduces the total number of adjustment devices needed while still enabling fuel consumption optimization through selective cam engagement.
3Adaptability or versatility
If the sliding mechanism is used to activate different cam geometries, then engine adaptability to different load conditions improves, but the manufacturing precision requirements increase
Solution Approach 1:
The cam selection system is segmented into discrete, well-defined cam geometries (first cam with first geometry, second cam with second geometry) rather than requiring continuous variable adjustment. This segmentation allows each cam profile to be manufactured with standard precision tolerances, while the sliding mechanism provides clean, discrete transitions between predefined cam engagement positions, reducing the overall manufacturing precision burden compared to a continuously variable system.
Data Source
Figure 1
AI summary
The invention relates to an internal combustion engine (10) with four cylinders (12a, 12b, 12c, 12d), wherein each cylinder (12a, 12b, 12c, 12d) has a first intake valve (14) and at least one second intake valve (16), wherein an intake camshaft (22) with actuating cams (30, 32, 34) assigned to the intake valves (14, 16) is provided for actuating the first intake valves (14) and the at least second intake valves (16), wherein each first intake valve (14) is assigned a first actuating cam (30) with a first cam geometry and a second actuating cam (32) with a second cam geometry, wherein the first cam geometry and the second cam geometry differ from each other at least over a part of their circumference.wherein the first actuating cam (30) and the second actuating cam (32) can be activated as required by means of at least one valve train adjusting device (40) by relative displacement relative to the associated first intake valve (14) in the axial direction of the intake camshaft (22) to actuate the respective first intake valve (14) and wherein at least one cylinder (12b, 12c) is assigned a first actuating cam (30) with a first cam geometry and a second actuating cam (32) with a second cam geometry to the second intake valve (16), wherein the first cam geometry and the second cam geometry differ from each other at least over part of their circumference,wherein the first actuating cam (30) and the second actuating cam (32) can be activated as required by means of at least one valve train adjusting device (40) by relative displacement relative to the associated second intake valve (16) in the axial direction of the intake camshaft (22) to actuate the second intake valve (16). The invention further relates to a method for operating an internal combustion engine (10).