Powertrain Control Reducing Lash-Induced Disturbances
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Solution Overview
Problem
Traditional engine control systems fail to accurately control engine output torque and do not provide rapid responses to control signals, leading to powertrain disturbances such as clunk or ringing sounds during transitions between negative and zero lash states.
Innovation Solution
A control system and method that determine rotational energy input during negative lash events and selectively limit engine speed increases to predetermined rates, using an energy determination module and speed control module to manage torque output and torque converter slip rates, thereby reducing powertrain disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional engine control systems are used to control engine output torque, then the control system is simple, but the torque control accuracy is poor and response speed is slow
Solution Approach 1:
The control system segments the negative lash event into three distinct periods (first, second, and third periods) with different control strategies for each period. This segmentation allows precise control of engine speed increases during specific critical phases while maintaining simpler control during other phases, thereby improving torque control accuracy without uniformly increasing system complexity throughout the entire operation cycle.
Solution Approach 2:
The control system dynamically adjusts the engine speed increase rate based on the current period of the negative lash event. During the second period, the system limits the engine speed increase to a first predetermined rate, while during the third period, it allows increases at a second predetermined rate. This dynamic adjustment optimizes torque control accuracy by matching control intensity to the specific operational phase, avoiding unnecessary complexity in all conditions.
2Speed
If traditional engine control systems are used, then the system structure is simple, but the response speed to control signals is slow
Solution Approach 1:
The control system identifies the negative lash event and its periods in advance, then proactively applies appropriate speed limitation strategies during the second period before the disturbance fully manifests. This preliminary action during the critical second period improves response speed by preparing and executing control measures at the optimal moment, rather than reacting after the disturbance occurs.
Solution Approach 2:
The control system continuously monitors engine operating conditions to detect negative lash events and determines which period is currently active. Based on this feedback, it automatically adjusts the engine speed increase rate limitation strategy. This feedback mechanism enables rapid response to control signals by continuously adapting control actions to the current system state, improving response speed without requiring overly complex hardware.
3Object-affected harmful factors
If engine speed is rapidly increased during negative lash events, then the control response is fast, but powertrain disturbances such as clunk or ringing sounds occur
Solution Approach 1:
The control system applies preliminary anti-action by limiting the engine speed increase rate during the second period of the negative lash event, before the powertrain components fully re-engage and potential disturbances occur. This preventive measure counteracts the tendency for rapid speed increases that would cause clunk or ringing sounds, thereby reducing powertrain disturbances while allowing faster speed increases during other periods when disturbances are less likely.
Data Source
AI summary
A control system for a powertrain includes an energy determination module and a speed control module. The energy determination module determines a rotational energy input to the powertrain during a first period of a negative lash event of the powertrain. The speed control module selectively limits an increase in a rotational speed of the engine to a first predetermined rate based on the rotational energy during a second period of the negative lash event following the first period. The rotational energy is based on an acceleration rate of the rotational speed, and the speed control module limits the increase when the acceleration rate is greater than a predetermined acceleration rate. The speed control module further selectively increases the rotational speed at a second predetermined rate during a third period beginning at an end of the second period. A related method is also provided.