Hybrid Transmission Neutral Verification for Engine Start Control
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Solution Overview
Problem
Hybrid vehicles require multiple components for engine start, including a motor and sensors, increasing complexity and part count, and there is a need to minimize these to enhance efficiency and reduce costs.
Innovation Solution
A vehicle system with an internal combustion engine and electric motor uses a transmission state detector and a separate rotation information detector to determine if the transmission is in a neutral state, generating determination torque to verify the state before allowing engine start, thereby reducing the need for additional sensors and motors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a motor and sensor are added for engine start control in hybrid vehicles, then the engine start function is improved, but the number of parts and system complexity increase
Solution Approach 1:
The patent makes the electric motor serve dual functions: propulsion during vehicle operation and engine starting when needed. The control unit manages the electric motor to generate determination torque for verifying transmission neutral state, and also uses it for actual engine starting, eliminating the need for a separate starter motor
Solution Approach 2:
The system uses the electric motor's own rotational information and torque generation capability to verify transmission state and perform engine starting autonomously, without requiring external dedicated starting components. The control unit leverages existing sensor data to determine neutral state, making the system self-sufficient
2Measurement precision
If multiple sensors are mounted for transmission state detection, then the detection accuracy is improved, but the number of sensors and cost increase
Solution Approach 1:
The control unit uses feedback from the rotation information detector to verify whether the transmission is in neutral state. By comparing the detected rotational speed against predetermined thresholds, the system achieves accurate state verification using existing sensor data without adding dedicated transmission state sensors
Solution Approach 2:
The rotation information detector, originally intended for monitoring transmission operation, is also used to verify neutral state for engine starting. This multi-functional use of existing sensors eliminates the need for separate detection devices while maintaining detection accuracy
3Reliability
If determination torque is applied to verify neutral state, then the accuracy of engine start control is improved, but vehicle behavior changes may occur
Solution Approach 1:
The control unit applies determination torque only partially and temporarily to verify neutral state, rather than continuously or excessively. The torque is applied just enough to generate detectable rotational information for verification, then stopped before causing significant vehicle movement or discomfort
Solution Approach 2:
The determination torque is applied periodically in controlled intervals rather than continuously. The control unit applies torque, monitors the rotational response to verify neutral state, then stops the torque application, creating a periodic cycle that limits overall vehicle behavior changes while maintaining verification accuracy
Data Source
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AI summary
A vehicle (1) according to one aspect includes: an internal combustion engine (2) and an electric motor (3) as traveling driving sources; a driving wheel (9); a transmission (4); a transmission state detector (31); a rotation information detector (33); and a controller (30) including processing circuitry. The processing circuitry determines whether or not state information received from the transmission state detector (31) is neutral information indicating that the transmission (4) is in a neutral state where power transmission between an input shaft (5) and an output shaft (6) is cut. After the processing circuitry determines that the state information is the neutral information, the processing circuitry controls the electric motor (3) such that the electric motor (3) generates predetermined determination torque. The processing circuitry determines based on rotation information received from the rotation information detector (33) whether or not there is an error in the neutral information. When the processing circuitry determines that there is no error in the neutral information, the processing circuitry permits engine start control of transmitting power from the electric motor (3) to the internal combustion engine (2) to start the internal combustion engine (2). When the processing circuitry determines that there is the error in the neutral information, the processing circuitry restricts the engine start control.