Cam Switching Device Solving Base Circle Angle Constraints
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Solution Overview
Problem
The existing cam-switching devices face challenges in switching between cams when the angle range of the base circle is insufficient, particularly in multi-cylinder engines, leading to complex configurations and difficulties in synchronizing valve operations across multiple cylinders.
Innovation Solution
A cam-switching device and method that utilize dual cam shafts with electromagnetic solenoids and slide grooves, allowing for selective switching between standard and low-speed intake cams, and fast-opening and standard exhaust cams, even when the base circle angle range is insufficient, by controlling the cam shaft movement through an electronic control unit (ECU) to manage valve operations and prevent abnormal sounds or inefficiencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a cam-switching device is provided per cylinder to enable cam switching, then valve characteristics can be optimized for each cylinder, but the number of cam-switching devices increases to two times the number of cylinders and the configuration becomes complicated
Solution Approach 1:
The patent combines multiple cam-switching devices into a single integrated device that can control multiple cylinders simultaneously. The cam switching mechanism is designed to operate collectively for the intake side and exhaust side of multiple cylinders, reducing the total number of devices while maintaining the ability to optimize valve characteristics across different cylinders through selective cam profile engagement.
2Device complexity
If cam switching is performed collectively for multiple cylinders to simplify configuration, then device complexity is reduced, but the angle range of base circle may be insufficient for switching when valve opening and closing periods are large
Solution Approach 1:
The patent introduces a radial adjustment mechanism that allows the cam shaft to move in the radial direction in addition to the axial direction. This adds a new dimension of movement, enabling the cam switching to occur even when the base circle angle range is insufficient, as the radial movement provides an alternative path for cam engagement and disengagement.
Solution Approach 2:
The cam switching is performed in advance during the base circle period before the valve lifting begins. By utilizing the base circle angle range efficiently and completing the switching action before valve operation starts, the system ensures smooth transitions between cam profiles without interfering with the valve opening and closing periods.
3Device complexity
If the cam shaft is slid only in the axis direction to switch between cams, then the switching mechanism is simple, but switching cannot be performed when the base circle angle range is insufficient
Solution Approach 1:
The patent transforms the static cam shaft into a dynamic component that can move in multiple directions (axial and radial). This dynamic capability allows the cam shaft to adapt its position based on the specific switching requirements, enabling cam profile transitions even when the base circle angle range is limited, while maintaining a relatively simple overall mechanism structure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables smooth switching between cams without hindrance, preventing abnormal sounds and maintaining engine efficiency by controlling valve operations across multiple cylinders, even when the base circle angle range is insufficient, thereby simplifying the configuration and improving fuel efficiency.
Implementation Method 1
an electromagnetic solenoid that generates an electromagnetic force in an axis direction
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
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.