Vehicle Shift-Down Torque Control for Shock Reduction
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Solution Overview
Problem
The existing control apparatus for vehicles with step-variable transmissions experiences delays in acceleration response and risks of 'backlash-elimination shock' due to torque resetting controls, which can lead to suboptimal control responses and increased risk of shock during shift-down actions.
Innovation Solution
A control apparatus that implements feedback control during the inertia phase of shift-down actions, restricts the increase of target torque, and uses an actual input torque increasing control to ensure the torque is higher than the target value before the inertia phase, while also reducing the torque capacity of releasing-side coupling devices earlier than engaging-side devices to minimize shock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the target value of input torque is restricted to prevent backlash-elimination shock, then the risk of shock is reduced, but the control response to acceleration requirement is delayed
Solution Approach 1:
The patent applies preliminary action by increasing the actual input torque before the inertia phase begins. When the accelerator pedal operation amount increases before shift-down, the control apparatus increases the actual input torque above the target value in advance, so that when the inertia phase starts, the torque is already at a level that enables rapid acceleration response without causing backlash-elimination shock.
Solution Approach 2:
The patent applies dynamics by making the input torque control flexible and adaptive. The control apparatus dynamically adjusts the actual input torque based on the timing relative to the inertia phase and the accelerator pedal operation amount. The torque can be higher than target before inertia phase, equal to target during inertia phase, and restricted after inertia phase, creating a dynamic torque profile that optimizes both response speed and shock prevention.
2Reliability
If torque resetting control is implemented after synchronization, then the input torque is reset to target value, but the acceleration response is delayed
Solution Approach 1:
The patent applies preliminary action by preparing the torque conditions before the inertia phase. The actual input torque is increased above the target value before shift-down begins, so that when the inertia phase starts and torque resetting control is implemented, the torque is already at an appropriate level. This eliminates the need for delayed torque adjustment after synchronization.
3Reliability
If the target torque increase is limited during shift-down, then backlash-elimination shock is prevented, but the inertia phase initiation is delayed
Solution Approach 1:
The patent applies preliminary action by increasing the actual input torque above the target value before the inertia phase begins. This preliminary torque increase ensures that when the shift-down action starts, the torque is already at a level that enables rapid gear change without causing backlash-elimination shock, thus maintaining high shift-down speed while preventing shock.
Solution Approach 2:
The patent applies dynamics by creating a time-varying torque control strategy. Before inertia phase: actual torque > target torque. During inertia phase: actual torque = target torque (restricted increase). After inertia phase: torque resetting control. This dynamic adjustment allows rapid shift-down while preventing shock at critical moments.
Data Source
AI summary
A control apparatus for a vehicle provided, with a step-variable transmission, includes: a feedback control portion; an input torque resetting control portion; a target input torque setting portion operated upon an increase of the accelerator pedal operation amount in the process of the shift-down action in a power-off state of the vehicle, to restrict an amount of increase of the input torque target value with respect to an amount of increase of an operator-required input torque value, so as to keep the target value not larger than an upper limit value until termination of the input torque resetting control; and an actual input torque increasing portion operated upon the increase of the accelerator pedal operation amount prior to initiation of the inertia phase, to implement an input torque increasing control to control the input torque so as to be larger than the target value, prior to the inertia phase initiation.