Hybrid Vehicle Gear Shift Control Using Torque Management
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Solution Overview
Problem
Conventional hybrid vehicle gear shifting methods experience shift shock and increased fuel consumption due to engine idle speed control in neutral or parking states, leading to vibration, noise, and reduced transmission durability.
Innovation Solution
The method involves controlling the torque of the engine and speed of the motor/generators in a hybrid vehicle by releasing clutches and brakes, determining the neutral condition, and using a first and second planetary gear set to minimize shift shock and optimize fuel efficiency during mode changes from parking or neutral to drive or reverse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the engine is controlled at idle speed in neutral or parking state, then the transmission can be prepared for mode change, but shift shock is generated and fuel consumption is increased
Solution Approach 1:
The patent changes the engine control parameter from idle speed control to torque control during neutral/parking state. Specifically, the engine torque is controlled to be substantially zero instead of maintaining idle speed, which eliminates unnecessary energy consumption while still preparing the transmission for mode change. This parameter change directly resolves the contradiction by eliminating fuel waste without compromising mode change capability.
2Ease of operation
If the engine is controlled at idle speed in neutral or parking state, then the transmission can be prepared for mode change, but vibration and noise are generated
Solution Approach 1:
The patent changes the engine control parameter from idle speed control to torque control during neutral/parking state. By controlling engine torque to be substantially zero, the engine operates more smoothly without the vibrations and noises associated with idle operation, while still maintaining readiness for mode change. This directly addresses the harmful vibrations and noises generated during idle operation.
3Ease of operation
If clutches and brakes are released for mode change, then transmission can shift from neutral to drive, but slip is formed and durability is decreased
Solution Approach 1:
The patent applies preliminary action by controlling the engine torque to be substantially zero during neutral/parking state before mode change occurs. This pre-conditioning of the engine state reduces the speed difference between engine and transmission during the transition, thereby minimizing slip when clutches and brakes are released. The preliminary torque control prepares the system for a smoother transition, reducing wear on transmission components.
4Power
If engine torque is controlled to output predetermined torque in drive or reverse state, then driving performance is maintained, but shift shock is generated during mode change
Solution Approach 1:
The patent applies preliminary action by controlling engine torque to be substantially zero during neutral/parking state before mode change. This creates a smooth transition state that eliminates sudden torque changes during mode switching. After mode change is complete, the engine torque is then controlled to output the predetermined torque needed for driving performance. This two-stage approach eliminates shift shock while maintaining power output.
Data Source
AI summary
A gear shifting method of a hybrid vehicle may include releasing a clutch and brake of a transmission and determining a neutral condition status, controlling torque of an engine connected to one operational element of a first planetary gear set in a neutral condition, and controlling speed of a first motor/generator connected to the other operational element of the first planetary gear set. Accordingly, a speed of the first and second motor/generator are controlled and a torque of the engine is controlled in a neutral or parking state of a shift lever such that a mode change becomes easy and the torque of the engine is continuously controlled to improve a shift quality and a driving performance and to save fuel, while the neutral or parking state is changed to a drive or reverse state or the drive or reverse state is changed to the neutral or parking state.