Intake Conduit Length Control with Asymmetric Hysteresis
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Solution Overview
Problem
Conventional intake control devices for straddle type vehicles, such as motorcycles, frequently change the length of the intake conduit near threshold values, leading to uncomfortable ride feelings due to frequent variations in engine load.
Innovation Solution
An intake control device with a determining means that adjusts the intake conduit length between a first and a second length based on engine load thresholds, where the second threshold is lower than the first, and considers the duration the engine load exceeds the first threshold, using a movable conduit to change the conduit length by connecting or disconnecting from a fixed conduit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the intake conduit length is changed based on a single threshold value for engine load, then the engine output characteristic can be adjusted, but the intake conduit length frequently changes when engine load varies near the threshold, causing uncomfortable ride feelings
Solution Approach 1:
The patent applies asymmetry by setting different threshold values for lengthening and shortening the intake conduit. The first threshold (7000 rpm) for lengthening is higher than the second threshold (6000 rpm) for shortening, creating an asymmetric hysteresis loop that prevents frequent switching near a single threshold point.
Solution Approach 2:
The patent implements periodic action through the hysteresis control mechanism where the intake conduit length changes in a cyclic pattern only when engine speed repeatedly exceeds the thresholds, rather than changing continuously with every fluctuation near the threshold.
2Productivity
If the intake conduit length is frequently adjusted to optimize engine performance, then the engine can adapt to varying loads, but the frequent changes cause unstable engine behavior and reduce ride comfort
Solution Approach 1:
The asymmetric threshold values create a buffer zone between 6000-7000 rpm where the intake conduit length remains stable, preventing reliability issues caused by frequent adjustments while still allowing performance optimization at extreme engine speeds.
Solution Approach 2:
The hysteresis mechanism acts as a cushioning buffer that absorbs the instability caused by frequent threshold crossings, preventing the harmful effect of rapid length changes while maintaining the beneficial effect of adaptive length adjustment at extreme conditions.
Data Source
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AI summary
The present invention relates to an intake control device for an engine (50) comprising: a change control means (11a) for changing a length of an intake conduit (30) between a first length (L1) and a second length (L2) shorter than the first length (L1); and a determining means (11b) for determining whether or not the length of the intake conduit (30) needs to be changed by the change control means (11a), wherein the determining means (11b) is configured to determine requirement that the first length (L1) is to be changed to the second length (L2) based on the condition that an engine load is higher than a first threshold value, and is configured to determine requirement that the second length (L2) is to be changed to the first length (L1) based on the condition that the engine load is lower than a second threshold value, and wherein the second threshold value is set lower than the first threshold value.