CVT Vehicle Control Device Managing Belt Slip and Clutch Shock
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Solution Overview
Problem
In vehicles with continuously variable transmissions, discrepancies between the operating positions of manual and pressure regulating valves can cause rapid hydraulic pressure increases, leading to clutch engagement shocks and belt slip due to insufficient belt sandwiching force, which existing solutions fail to adequately address across various shift lever positions.
Innovation Solution
A vehicle control device and method that determine the engagement state of a friction engaging element, calculate target line pressure and torque capacities based on input torque and belt capacity, and restrain slip between pulleys and power transmitting members to manage belt slip effectively, regardless of vehicle state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensing range of the inhibitor switch is configured wider than the switching range of the manual valve to enable detection, then the detection capability is improved, but a discrepancy occurs between the operating positions causing rapid hydraulic pressure increase and clutch engagement shock
Solution Approach 1:
The control device detects the discrepancy between the inhibitor switch position and manual valve position before the rapid hydraulic pressure increase occurs. When discrepancy is detected, the control device preliminarily reduces the instructed pressure to the pressure regulating valve, preventing the sudden clutch engagement and engagement shock before they happen.
Solution Approach 2:
The control device continuously monitors the positions of both the inhibitor switch and manual valve, comparing them in real-time. When a position discrepancy is detected, the system provides feedback control by adjusting the instructed pressure to the pressure regulating valve, thereby preventing the harmful effect of rapid hydraulic pressure increase.
2Object-affected harmful factors
If the instructed pressure to the clutch is reduced in case of discrepancy, then the clutch engagement shock is reduced, but the belt capacity becomes insufficient causing belt slip
Solution Approach 1:
The control device dynamically adjusts the instructed pressure to the pressure regulating valve based on the detected discrepancy state. The system applies different pressure control strategies depending on whether discrepancy is present, optimizing both shock reduction and belt capacity utilization in real-time according to the actual operating conditions.
Solution Approach 2:
The control device changes the instructed pressure parameter to the pressure regulating valve when discrepancy is detected. By adjusting this pressure parameter, the system prevents both the harmful effects of sudden clutch engagement and the potential belt slip that would occur with insufficient pressure, maintaining optimal operating parameters under discrepancy conditions.
3Reliability
If a preset belt capacity is configured to restrain belt slip, then belt slip is restrained in some conditions, but the discrepancy occurs in various shift lever positions with different input torques and speed ratios making a single preset capacity insufficient
Solution Approach 1:
The control device dynamically determines the instructed pressure to the pressure regulating valve based on the detected discrepancy state and current operating conditions. This dynamic adjustment allows the system to adapt to various shift lever positions, input torques, and speed ratios, providing effective belt slip restraint across all operating conditions rather than relying on a single preset capacity.
Solution Approach 2:
The system changes the instructed pressure parameter to the pressure regulating valve based on the discrepancy detection and current vehicle state. This parameter adjustment enables the belt capacity to be optimized for each specific operating condition (different shift lever positions, input torques, and speed ratios), achieving versatile adaptability across all scenarios.
Data Source
AI summary
A vehicle control device calculates a target line pressure based on an instructed torque capacity of a friction engaging element and a belt capacity when the friction engaging element is determined as not engaging. Belt capacity is calculated using an input torque of a continuously variable transmission mechanism. The device calculates torque down in a driving source based on an upper limit line pressure when the calculated target line pressure exceeds such line pressure. A limit torque capacity of the friction engaging element is calculated using the input torque and a belt capacity when the friction engaging element is determined as not engaging. The belt capacity is calculated using an actual line pressure. The device restrains a slip between pulleys and a power transmitting member using the target line pressure, the torque down, and the limit torque capacity when the friction engaging element is determined as not engaging.