Clutch Fill Pressure Control via Incremental Solenoid Pulses
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Solution Overview
Problem
Existing powertrain control systems for hybrid vehicles face challenges in precisely controlling clutch engagement states, leading to inefficiencies and potential component damage due to rapid clutch fill events, which can cause perceptible bumps and shorten component life, and lack accurate monitoring of clutch actuation status.
Innovation Solution
A method is introduced to control the powertrain by applying a series of incrementally changing command pressures through a pressure control solenoid connected to a clutch, monitoring pressure switch cycle times, and selecting a preferred command pressure to achieve a transient 'touching' state in the clutch, thereby optimizing clutch engagement and reducing wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If rapid clutch fill events are used to achieve quick engagement, then engagement speed is improved, but component wear increases and perceptible bumps occur
Solution Approach 1:
The patent applies periodic action by using a pressure control solenoid to deliver hydraulic pressure in controlled cycles rather than continuous rapid fill. The solenoid modulates pressure application to the clutch piston, creating a controlled engagement sequence that reduces shock and wear while maintaining engagement speed. This is achieved through pulsed hydraulic pressure application that gradually brings the clutch plates together.
Solution Approach 2:
The patent implements beforehand cushioning by introducing a compliant element (such as a spring or elastomeric component) between the clutch piston and the clutch plates. This cushioning element absorbs the impact energy during engagement, preventing direct shock transmission to the clutch plates and reducing wear. The cushioning is built into the clutch assembly structure to mitigate harmful effects before they occur.
2Device complexity
If traditional hydraulic control is used for clutch actuation, then system simplicity is maintained, but precise control of transient states is lost
Solution Approach 1:
The patent implements feedback by incorporating a pressure switch that monitors hydraulic pressure in the clutch actuation circuit. The pressure switch provides real-time information about clutch engagement status to the control system, enabling precise detection of transient states such as the 'touching' state where clutch plates first contact. This feedback loop allows the controller to adjust pressure application to achieve and maintain desired engagement states with high precision.
Solution Approach 2:
The patent uses an intermediary approach by introducing a pressure control solenoid as a mediator between the hydraulic system and the clutch actuation. The solenoid precisely controls hydraulic pressure delivery to the clutch piston, enabling fine-grained control of engagement states. Additionally, the pressure switch serves as an intermediary sensing element that translates physical clutch state into electrical signals for the control system.
3Ease of operation
If binary clutch operation is used, then control simplicity is maintained, but engagement state precision is reduced
Solution Approach 1:
The patent applies dynamics by transitioning from static binary clutch control to dynamic multi-state control. The pressure control solenoid enables the clutch to operate through multiple engagement states (disengaged, touching, partially engaged, fully engaged) by dynamically adjusting hydraulic pressure. This dynamic control allows precise manipulation of clutch engagement timing and force, improving both fuel efficiency and drivability while maintaining ease of operation through electronic control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for precise control of clutch engagement, improving drivability, reducing component wear, and enhancing the accuracy of clutch operation, leading to better fuel efficiency and extended component lifespan.
Implementation Method 1
applying through a series of clutch fill events a series of incrementally changing command pressures in a pressure control solenoid
Implementation Method 2
monitoring a pressure switch to indicate when the pressure switch is in a full feed state
Implementation Method 3
pressurized hydraulic oil is used to fill a clutch volume chamber and thereby displace a clutch piston in order to selectively apply a compression force
Data Source
AI summary
A method to control a powertrain including a transmission, an engine, and an electric machine includes applying through a series of clutch fill events a series of incrementally changing command pressures in a pressure control solenoid controllably connected to a clutch within the transmission, monitoring a pressure switch fluidly connected to the pressure control solenoid and configured to indicate when the pressure switch is in a full feed state, determining changes in cycle times of the pressure switch corresponding to sequential applications of the series of incrementally changing command pressures, selecting a preferred command pressure to achieve a transient state in the clutch based upon the changes in pressure switch cycle times, and controlling the clutch based upon the preferred command pressure.