Transmission Control Device for Sensor Failure Startability
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Solution Overview
Problem
Existing transmission control systems face challenges in ensuring vehicle startability and preventing shift shock when the rotation sensor of the variator's output side fails, limiting the freedom of action of the variator.
Innovation Solution
A transmission control device and method that includes a failure determination unit, a speed ratio control unit, and a gear position control unit, which fix the sub-transmission mechanism's gear position to the first speed gear position during a vehicle stop and in case of sensor failure, allowing for variable speed ratio control of the variator and sub-transmission mechanism to enhance startability and prevent shift shock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gear position of the sub-transmission mechanism is fixed to the first speed gear position upon sensor failure, then vehicle startability is ensured and freedom of action of the variator is enhanced, but shift shock may occur during vehicle stop
Solution Approach 1:
The patent applies dynamics by making the gear position fixing strategy adaptive rather than static. The control device dynamically adjusts the gear position upon sensor failure based on real-time detection of vehicle stop conditions. When the vehicle is detected to be stopped, the gear position is fixed to the first speed gear position to ensure startability; when the vehicle is moving, normal variable gear position control is maintained to prevent shift shock. This dynamic adaptation resolves the contradiction between ensuring startability and preventing harmful shift shock.
2Reliability
If the variator speed ratio is fixed to the maximum speed ratio upon sensor failure, then vehicle startability is ensured, but freedom of action of the variator is limited
Solution Approach 1:
The patent segments the control functions between the variator and the sub-transmission mechanism. Upon sensor failure, instead of fixing the variator speed ratio (which would limit its freedom of action), the control device fixes only the gear position of the sub-transmission mechanism to the first speed gear position. This segmentation allows the variator to continue operating with variable speed ratios, maintaining its adaptability and freedom of action, while the sub-transmission mechanism provides the necessary startability guarantee through its fixed gear position.
3Reliability
If the gear position is fixed to the first speed gear position upon sensor failure, then vehicle startability is ensured, but fuel efficiency deteriorates due to inability to use higher gear ratios
Solution Approach 1:
The patent applies dynamics by making the gear position fixing strategy adaptive rather than static. The control device dynamically adjusts the gear position upon sensor failure based on real-time detection of vehicle stop conditions. When the vehicle is detected to be stopped, the gear position is fixed to the first speed gear position to ensure startability; when the vehicle is moving, normal variable gear position control is maintained to prevent shift shock.
4Object-generated harmful factors
If the gear position is fixed to the first speed gear position during vehicle stop upon sensor failure, then shift shock is prevented, but startability may be compromised if the gear position upon failure determination is the second speed gear position
Solution Approach 1:
The patent applies preliminary action by proactively fixing the gear position to the first speed gear position when the vehicle is detected to be stopped at the moment of sensor failure. This preliminary fixing action ensures that the transmission is in a safe, startable state before any potential start attempt occurs. By detecting the vehicle stop condition and fixing the gear position in advance, the system prevents both shift shock during stopping and ensures startability for subsequent vehicle restarts.
Data Source
AI summary
In a transmission control device, a controller determines failure of a rotation sensor. A hydraulic control circuit and the controller variably control a speed ratio of a variator. The hydraulic control circuit and the controller variably control a gear position of a sub-transmission mechanism, and in a case where the failure is determined, fix the gear position of the sub-transmission mechanism to first speed. The hydraulic control circuit and the controller fix the gear position of the sub-transmission mechanism to the first speed during a vehicle stop in a case where the gear position of the sub-transmission mechanism upon a determination of the failure is second speed.