Shift Range Control Apparatus Backlash Compensation

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Solution Overview

Problem

Conventional shift range control apparatuses face challenges in accurately positioning a detent plate due to the large driven torque of motors like DC brushless motors when power is not supplied, making it difficult to place the roller in the recessed part using the detent spring's pushing force.

Innovation Solution

A shift range control apparatus that includes a DC brushless motor, a detent plate, and a detent spring, with a current detection part, a current increase check part, a motor rotation stop part, and a reverse driving part, which detects and increases the motor current, stops the motor rotation, and reverses the motor direction to accurately position the detent plate by rotating the backlash angle, ensuring the roller is centered in the recessed part.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a DC brushless motor with permanent magnets is used to improve response characteristic, then the response characteristic is improved, but the driven torque under no power supply becomes larger, making it difficult to position the roller in the recessed part using detent spring force

Engineering Contradiction:

Improveresponse characteristicVSAvoiddriven torque under no power supply

Core Design Contradiction:

SpeedVSForce

Solution Approach 1:

The control part performs preliminary actions by detecting motor current and determining when the roller has reached the recessed part before actually stopping the motor. This allows the system to prepare for the positioning action in advance, ensuring that the detent spring can properly position the roller even when the motor has large no-power torque.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control part uses feedback from current detection to monitor the motor's operation and determine when the roller has reached the recessed part. This feedback mechanism allows the system to adjust its control strategy based on real-time conditions, ensuring accurate positioning despite the large driven torque.

Inventive Principle:

Principle #23Feedback

2Force

If power supply to the motor is stopped to allow detent spring to position the roller, then positioning can be achieved with low torque motors, but with high torque motors the roller cannot be properly positioned by the detent spring

Engineering Contradiction:

Improvedriven torque under no power supplyVSAvoidpositioning accuracy of detent plate

Core Design Contradiction:

ForceVSManufacturing precision

Solution Approach 1:

The invention replaces the purely mechanical positioning system (relying on detent spring force) with an electromechanical control system. The control part uses electrical current detection and intelligent control to supplement the mechanical positioning, allowing the system to achieve accurate positioning even when the mechanical detent spring force is insufficient against the motor's no-power torque.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If the motor is stopped before positioning, then the detent spring can position the roller, but the positioning accuracy is insufficient when the motor has large no-power torque

Engineering Contradiction:

Improvepositioning reliability with detent springVSAvoidpositioning accuracy of detent plate

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The control part acts as an intermediary between the motor and the detent positioning mechanism. It monitors the motor's operation through current detection and determines the optimal timing for stopping the motor, allowing the detent spring to properly position the roller. This intermediary control ensures both reliability and accuracy in the positioning process.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

This solution enables accurate positioning of the detent plate even with motors that have significant torque under no power supply, improving the shift range control's precision and reliability.

Implementation Method 1

a current detection part, configured to detect a current value, which corresponds to a driving current supplied to drive the motor

Methodology Applied

Scientific EffectElectrical current detection: Conduction (electrical)

Implementation Method 2

The motor has a motor shaft for outputting torque

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS10138999B2Shift range control apparatus

Publication Date: 2018.11.27 DENSO CORP

AI summary

A control circuit switches over a shift range by controlling driving of a motor to rotationally drive a detent plate. A current detection circuit detects a current value corresponding to a driving current supplied to drive the motor. A current increase check part performs check processing to check whether the current value detected by the current detection circuit has increased. A motor rotation stop part stops rotation of the motor when the current increase check part determines that the current has increased. A reverse driving part reverses the rotation direction of the motor and rotationally drives the motor after stopping of the motor by the motor rotation stop part.