Vehicular Drive Torque Control Apparatus for Engagement Shock Suppression
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Solution Overview
Problem
Existing control apparatuses for vehicular drive apparatuses with electric differential portions face challenges in controlling torque output effectively, particularly when synchronization control using motors is not feasible due to low battery state of charge or high hydraulic fluid viscosity, leading to increased engagement shocks.
Innovation Solution
A control apparatus that selects between two torque control methods based on vehicle conditions: one controlling engagement pressure for the engagement device and the other controlling reaction torque borne by the motor, ensuring appropriate torque output regardless of conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If synchronization control using motors is executed to reduce rotational speed difference, then engagement shock is suppressed, but it cannot be executed when battery state of charge is low
Solution Approach 1:
The system changes the control parameter from motor-based synchronization control to engagement pressure-based control when battery state of charge is low. The ECU detects battery SOC and switches control methods accordingly, using engagement pressure adjustment instead of motor torque control to suppress engagement shock under constrained energy conditions
Solution Approach 2:
The engagement pressure acts as an intermediary control mechanism when direct motor synchronization is not feasible. By controlling the engagement pressure of the friction engagement device, the system can still achieve smooth power transmission transition without directly using motor torque control, thus suppressing engagement shock through a mediating parameter
2Object-affected harmful factors
If engagement pressure control is used to suppress shock, then engagement shock is reduced, but it is difficult to execute accurately when hydraulic fluid temperature is extremely low
Solution Approach 1:
The system changes the control parameter from engagement pressure control to reaction torque control when hydraulic fluid temperature is extremely low. The ECU detects hydraulic fluid temperature and switches to controlling the reaction torque of the motor, which provides more accurate and reliable control under low-temperature conditions where hydraulic fluid viscosity affects pressure control accuracy
Solution Approach 2:
The system replaces hydraulic-based engagement pressure control with motor-based reaction torque control when temperature conditions are unfavorable. This substitution uses electrical/motor control instead of hydraulic control, avoiding the issues of high hydraulic fluid viscosity that prevent accurate pressure control in extreme cold
3Speed
If quick engagement is executed to switch power transmission path, then response speed is improved, but engagement shock increases when rotational speed difference is not reduced
Solution Approach 1:
The system performs preliminary synchronization control by adjusting motor torque before engagement occurs. The ECU controls the reaction torque of the motor to reduce the rotational speed difference between the friction engagement device and the power transmission path ahead of time, ensuring that when quick engagement is executed, the shock is minimized because the speed mismatch has already been corrected
Solution Approach 2:
The system maintains continuous control of the motor reaction torque during the engagement process. Rather than discrete adjustments, the motor torque is continuously regulated to smoothly reduce rotational speed difference throughout the engagement sequence, allowing both quick engagement and shock suppression through uninterrupted control action
Data Source
AI summary
A torque control selection portion selects one of a first torque control portion and a second torque control portion as a control portion that controls a torque output from an automatic transmission, based on a vehicle condition. The first torque control portion controls the output torque by controlling an engagement pressure for a first clutch or a second clutch. The second torque control portion controls the output torque by controlling a reaction torque borne by a first motor when transmission of power is permitted in a shift mechanism.