Shift Range Control Apparatus Abnormality Detection

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Solution Overview

Problem

Existing shift range changeover systems for automatic transmissions can erroneously change over to a different shift range due to abnormal detection signals from encoders, leading to incorrect gear selection by the vehicle driver.

Innovation Solution

A control apparatus that detects the rotation position of a motor and performs feedback control to change the shift range to a target position, but prohibits feedback control after a predetermined permission period to prevent erroneous changes, and determines temporary or persistent abnormalities to implement failsafe processing, ensuring the shift range remains as selected by the driver.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If feedback control is continuously performed based on encoder detection output, then the motor rotation position can be accurately controlled to achieve target shift range, but abnormal detection signals cause erroneous shift range changes

Engineering Contradiction:

Improverotation position detection accuracyVSAvoidshift range control reliability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The control apparatus prohibits feedback control within a predetermined period after shift range changeover is completed. This preliminary action prevents abnormal detection signals that may occur during the stabilization phase from causing erroneous shift range changes, while still allowing accurate feedback control during normal operation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The feedback control is periodically enabled and disabled based on the timing relative to shift range changeover. By creating periodic control windows (enabled during stable operation, disabled during transition periods), the system balances measurement precision with reliability

Inventive Principle:

Principle #19Periodic action

2Reliability

If feedback control is prohibited to prevent erroneous changes, then shift range reliability is improved, but the system cannot correct detection abnormalities promptly

Engineering Contradiction:

Improveshift range control reliabilityVSAvoidresponse time to detect abnormalities

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control apparatus introduces an intermediary timing mechanism (feedback control permission period) that mediates between the need for continuous monitoring and the risk of erroneous control. This timing-based intermediary allows the system to balance reliability with timely abnormality detection

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS8311716B2Control apparatus for shift range changeover device

Publication Date: 2012.11.13 DENSO CORP

AI summary

A control apparatus for a shift range changeover device determines temporary abnormality, when a detection output of a rotation position of a motor continues to be abnormal for a first abnormality determination period. The control apparatus further determines persistent abnormality and performs predetermined failsafe processing, when the detection output further continues to be abnormal for a second abnormality period following the first abnormality period. If the temporary abnormality is determined within a feedback control permission period, motor feedback control is prohibited to control the shift range to the neutral range. If the temporary abnormality is determined after the feedback control permission period, the same control operation as before the temporary abnormality is performed.