Variable Compression Ratio Engine Sensor Isolation
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Solution Overview
Problem
In variable compression ratio internal combustion engines, the detection accuracy of the rotation sensor deteriorates due to vibrations and deformation when the control shaft collides with stopper faces, affecting the accuracy of compression ratio reference position learning.
Innovation Solution
The engine features separate regulation parts for the control shaft and rotation shaft, allowing the rotation sensor to detect one shaft while the other is mechanically regulated, reducing interference from vibrations and deformation during the learning process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the rotation sensor and regulation parts are provided in the same housing, then the structure is compact, but the detection accuracy of the rotation sensor deteriorates due to vibrations and deformation when the control shaft collides with stopper faces
Solution Approach 1:
The patent divides the housing into two separate housings: a first housing for the control shaft and regulation parts, and a second housing for the rotation sensor. This segmentation isolates the sensor from vibrations and deformations caused by mechanical regulation, resolving the contradiction between structural compactness and measurement precision.
Solution Approach 2:
The rotation sensor is extracted from the first housing and placed in a separate second housing. This extraction removes the sensor from the harmful environment of vibrations and deformations, allowing the regulation parts to function without compromising sensor accuracy.
2Reliability
If the control shaft is mechanically regulated by stopper faces, then the compression ratio range is controlled, but vibrations and deformation occur that affect sensor detection accuracy
Solution Approach 1:
The system is segmented into two separate housing units, allowing the control shaft with stopper faces to be isolated from the rotation sensor. This enables reliable compression ratio control through mechanical regulation while preventing vibrations from affecting sensor measurements.
Solution Approach 2:
A speed reducing mechanism with gear reduction acts as an intermediary between the control shaft and the rotation sensor. This intermediary reduces the transmission of vibrations and deformations from the mechanical regulation process to the sensor, maintaining both control reliability and measurement precision.
3Productivity
If the rotation sensor detects the control shaft position during collision with stopper faces, then the compression ratio reference position can be learned, but the learning accuracy deteriorates due to vibrations
Solution Approach 1:
By segmenting the housing into separate units for the control shaft and rotation sensor, the system enables reference position learning without the detrimental effects of vibrations. The sensor remains in a stable environment while the control shaft performs its regulatory function.
Solution Approach 2:
The system performs reference position learning in a predetermined state where the control shaft is mechanically regulated by the stopper faces. The separate housing configuration ensures that this preliminary action occurs without vibration-induced errors, enabling accurate learning.
Data Source
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AI summary
A variable compression ratio internal combustion engine includes a control shaft (13) rotatably supported by an engine body, a variable compression ratio mechanism (10) for changing an engine compression ratio in accordance with a rotational position of the control shaft (13), an actuator (21) that rotatively drives the control shaft (13), and a speed reducing mechanism (22) for reducing a rotational power of the actuator (21) and for transmitting the speed-reduced power to the control shaft (13). The speed reducing mechanism (22) has a rotation shaft (24) rotatably supported in a housing (26) fixed to the engine body and a lever (25) that connects the rotation shaft (24) and the control shaft (13). Located in the engine body is a first regulation part (42) for mechanically regulating the control shaft (13) to a position of maximum rotation on one side of a low compression ratio side and a high compression ratio side. Also located in the housing (26) is a second regulation part (41) for mechanically regulating the rotation shaft (24) to a position of maximum rotation on the other side of the low compression ratio side and the high compression ratio side.