Throttle Device Backlash Compensation via Intermediate Shaft

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Solution Overview

Problem

Conventional throttle devices face challenges in accurately detecting the rotation angle of the throttle shaft due to backlash in the gear meshing portion, leading to unreliable measurements and bulkiness when the sensor is positioned near the throttle shaft.

Innovation Solution

A throttle device with a sensor detecting the rotation angle of a rotating shaft different from the throttle shaft, utilizing a throttle angle calculation unit to subtract the backlash angle from the detected rotation angle to accurately determine the throttle shaft's rotation angle, thereby eliminating backlash and ensuring precise angle detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the sensor directly detects the rotation angle of the throttle shaft, then the measurement precision is improved, but the device complexity and size increase due to the sensor projecting from the throttle device

Engineering Contradiction:

Improverotation angle detection accuracyVSAvoidthrottle device structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces an intermediate shaft as a mediator between the throttle shaft and the sensor. The intermediate shaft transmits rotational motion from the throttle shaft to the sensor, allowing the sensor to be positioned away from the throttle shaft while still accurately detecting its rotation angle, thus avoiding the need for the sensor to project from the throttle device

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent segments the detection system by separating the sensor from the throttle shaft directly. The intermediate shaft acts as a separate transmission component that bridges the gap between the throttle shaft and sensor, enabling modular positioning and reducing overall device complexity

Inventive Principle:

Principle #1Segmentation

2Device complexity

If the sensor detects the rotation angle of the intermediate shaft, then the device complexity is reduced, but the measurement precision deteriorates due to backlash in the gear meshing portion

Engineering Contradiction:

Improvethrottle device structureVSAvoidrotation angle detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent converts the harmful effect of backlash into a beneficial one by intentionally designing a pre-load mechanism that applies force to eliminate backlash in the gear meshing portion. This pre-load converts what would normally be a source of error into a means of ensuring precise mechanical coupling between the intermediate shaft and throttle shaft

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent applies preliminary anti-action by introducing a pre-load force before normal operation to counteract the potential backlash in the gear meshing portion. This pre-load ensures that the mechanical connection remains tight and accurate throughout operation, preventing measurement errors

Inventive Principle:

Principle #9Preliminary anti-action

3Power

If the throttle valve needs to accurately follow the accelerator handler in lightweight vehicles, then the power weight ratio is improved, but the measurement precision requirement increases, making the detection system more complex

Engineering Contradiction:

Improvepower weight ratioVSAvoidthrottle valve opening accuracy

Core Design Contradiction:

PowerVSMeasurement precision

Solution Approach 1:

The intermediate shaft serves as a mediator that provides a stable, accurate rotational reference for the sensor. By detecting the intermediate shaft's rotation angle through the pre-loaded gear mechanism, the system achieves high measurement precision without requiring complex direct detection arrangements on the throttle shaft

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces complex direct mechanical coupling between the sensor and throttle shaft with a gear-based transmission system. This mechanical substitution allows the sensor to be positioned optimally while maintaining accurate detection through the intermediate shaft and pre-loaded gear mechanism

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP2949905B1Engine with throttle device, and engine-driven vehicle

Publication Date: 2017.09.06 YAMAHA MOTOR CO LTD

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AI summary

An engine with a throttle device includes a throttle valve (24) provided in an intake passage (31) of the engine. The engine includes a throttle shaft (27) that rotates integrally with a valve element (28) of the throttle valve (24), a spring member that biases the valve element (28) in a direction to close, and a throttle valve driving motor (26) connected to the throttle shaft (27) via a gear mechanism (25). The engine includes a sensor (42) that detects the rotation angle of a rotating shaft (43) different from the throttle shaft (27) in the gear mechanism (25), and a throttle angle calculation unit that obtains the rotation angle θ2 of the throttle shaft (27) using the detection value of the sensor (42). The throttle angle calculation unit calculates the rotation angle θ2 of the throttle shaft (27) by subtracting a backlash angle α from the detection angle of the sensor (42). It is possible to provide an engine with a throttle device capable of accurately detecting the rotation angle of the throttle shaft while employing an arrangement that causes the sensor to detect the rotation angle of the rotating shaft different from the throttle shaft.