Electric Vehicle Gear Shifting Control Neutral Range Torque
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Solution Overview
Problem
Conventional electric vehicles experience delays in start-off due to the hydraulic-pressure-generating pump stopping when the vehicle is stopped, making it difficult to select the start-off gear before the accelerator pedal is depressed, and there are issues with consistent transition from neutral to travel range due to the coupling clutch's engagement time and meshing positions.
Innovation Solution
An electric vehicle gear changing device with a stepped transmission and gear shifting control means that sets the neutral range to prevent the electric motor from generating torque when the accelerator is pressed, and engages the first-gear-engaging element in advance when the neutral range is selected, allowing for rapid start-off by preparing the transmission for first gear before transitioning to the travel range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the hydraulic-pressure-generating pump is stopped when the vehicle is stopped, then energy consumption is reduced, but start-off response time increases due to inability to select gear in advance
Solution Approach 1:
The patent applies preliminary action by enabling the hydraulic-pressure-generating pump to operate in advance during neutral range selection, before the travel range is actually selected. This allows the hydraulic system to be pressurized and the first-gear-engaging element to be prepared for engagement before the driver intends to move, eliminating start-off delays while minimizing energy consumption by limiting pump operation to the neutral range period only.
2Reliability
If the coupling clutch engagement time is extended to ensure reliable meshing, then gear engagement reliability improves, but start-off response time increases
Solution Approach 1:
The patent applies preliminary action by performing the coupling clutch engagement operation during the neutral range selection period, before the travel range is selected. This preliminary engagement ensures the gear is ready for immediate power transmission when the travel range is selected, achieving reliable meshing without delaying the actual start-off response.
Solution Approach 2:
The patent segments the gear engagement process into two distinct phases: (1) neutral range selection phase where the coupling clutch engages and hydraulic pressure builds, and (2) travel range selection phase where power transmission begins. This segmentation allows the engagement preparation to occur separately from the actual start-off action, ensuring reliability without compromising response time.
3Loss of time
If the first-gear-engaging element is engaged in advance during neutral range, then start-off response improves, but risk of unintended torque generation increases
Solution Approach 1:
The patent applies local quality by creating a specific operational condition where the electric motor is prohibited from generating torque during neutral range selection, while allowing normal torque generation in travel range. This localized control of torque generation capability ensures that the first-gear-engaging element can be engaged in advance without risk of unintended vehicle movement, as the motor is simply disabled during the neutral phase.
Solution Approach 2:
The patent uses the neutral range selection state as an intermediary condition that decouples the engagement preparation from torque generation. During this intermediary state, the coupling clutch can engage and hydraulic pressure can build without causing vehicle movement, since the electric motor is prohibited from generating torque. This intermediary phase safely bridges the gap between engagement preparation and actual power transmission.
Data Source
AI summary
A gear shifting control device is provided with a driving motor-generator, an automatic transmission provided in a drivetrain and a gear shifting controller. The automatic transmission has a P range, an N range and a D range as selectable range positions. The gear shifting controller changes the gears in the automatic transmission. The gear shifting controller sets the N range of the automatic transmission to be a range over which the driving motor-generator is not caused to generate torque even when a operation for depressing an accelerator pedal has been performed, and places a coupling clutch in an engaged state in first gear when the N range is selected.