Accelerator Lever Stop Control for Electric Wheelchair Motors

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Solution Overview

Problem

Existing electric wheelchair motor control systems lack convenience in stopping the electric motor, requiring users to return the accelerator lever to a neutral position, which can be cumbersome and inefficient.

Innovation Solution

A motor control system with an accelerator lever, angle sensor, and torsion springs that allow the user to stop the electric motor by increasing the lever operation, featuring a first torsion spring for returning the lever and a second torsion spring that increases the force required at a predetermined angle, enabling intuitive stopping without returning to neutral.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the accelerator lever is returned to the neutral position to stop the electric motor, then the motor can be stopped, but the operation becomes cumbersome and inconvenient

Engineering Contradiction:

Improveconvenience of stopping the electric motorVSAvoidtime required to return the accelerator lever to neutral position

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

Instead of requiring the user to return the accelerator lever to the neutral position to stop the motor (conventional approach), the invention inverts the logic by detecting when the lever exceeds a predetermined rotation angle and automatically stopping the motor. This allows the user to stop the motor by simply increasing the lever operation further, eliminating the need to return to neutral and significantly improving operational convenience.

Inventive Principle:

Principle #13The other way round (Inversion)

2Ease of operation

If a torsion spring is used to return the accelerator lever to the reference position, then the lever returns automatically, but the system requires additional space for the elastic member

Engineering Contradiction:

Improveautomatic return of accelerator leverVSAvoidspace required for the torsion spring

Core Design Contradiction:

Ease of operationVSVolume of moving object

Solution Approach 1:

The invention nests the torsion spring within the existing rotational mechanism by having the rotation shaft extend through the coil portion of the spring. This nested arrangement allows the torsion spring to be integrated into the existing structure without requiring additional external space, while still providing the necessary elastic force to return the accelerator lever to its reference position.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Volume of moving object

If the rotation shaft is passed through the coil portion of the torsion spring, then space is reduced, but the arrangement of other components becomes more constrained

Engineering Contradiction:

Improvespace occupied by the elastic memberVSAvoidcomponent arrangement flexibility

Core Design Contradiction:

Volume of moving objectVSDevice complexity

Solution Approach 1:

The rotation shaft serves multiple functions simultaneously: it acts as the rotational axis for the accelerator lever, passes through the torsion spring to enable space-efficient mounting, and provides structural support for the entire mechanism. This multi-functional design reduces the need for separate components and increases flexibility in arranging other system components within the available space.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

Enhances user convenience by allowing motor stoppage without returning the lever to neutral, reduces system size, and increases component arrangement flexibility through shared space utilization.

Implementation Method 1

a first torsion spring including a coil portion inside of which a rotation shaft of the accelerator lever extends to apply a first elastic force in a second rotation direction in an opposite direction to the first rotation direction to the accelerator lever

Methodology Applied

Scientific EffectElastic force: Elasticity

Implementation Method 2

a second torsion spring including a coil portion inside of which the rotation shaft of the accelerator lever extends to apply a second elastic force in the second rotation direction to the accelerator lever

Methodology Applied

Scientific EffectElastic force: Elasticity

Data Source

PatentUS12199537B2Motor control system, drive unit and electric vehicle

Publication Date: 2025.01.14 YAMAHA MOTOR CO LTD

AI summary

A motor control system for use in an electric vehicle includes an accelerator lever operable by a user, a controller configured or programmed to control an electric motor to generate a drive power to drive the electric vehicle, wherein a rotation speed of the electric motor is increased in response to an increase in a first rotation angle in a first rotation direction of the accelerator lever from a reference position of the accelerator lever, and a first torsion spring including a coil portion inside of which a rotation shaft of the accelerator lever extends to apply a first elastic force in a second rotation direction opposite to the first rotation direction. The controller is configured or programmed to perform a control to stop the electric motor upon detecting that the first rotation angle is equal to or greater than a first predetermined rotation angle.