Electro-Hydraulic Multispeed Transmission Control for Fault-Tolerant Shifts
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Solution Overview
Problem
The complexity of controlling multispeed transmissions increases with the need for precise clutch engagement and fault tolerance, especially in scenarios like loss of electrical power, due to the increasing number of forward and reverse ranges, which existing systems struggle to manage effectively.
Innovation Solution
An electro-hydraulic control system with a controller, fluid source, torque-transmitting mechanisms, trim systems, shift valves, and solenoids is implemented to selectively apply hydraulic pressure to achieve multiple ranges, ensuring correct clutch engagement and fault tolerance by using a combination of shift solenoids, trim valves, and boost valves to manage clutch pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of forward and reverse ranges is increased to improve fuel economy, then the adaptability of the transmission system is improved, but the device complexity increases due to more torque-transmitting mechanisms and control elements
Solution Approach 1:
The boost valve serves multiple functions: it controls hydraulic pressure to torque-transmitting mechanisms, provides fault detection capability, and enables default range selection. This multi-functionality reduces the need for separate dedicated components for each function, thereby managing complexity while supporting multiple ranges
Solution Approach 2:
The boost valve acts as an intermediary component between the hydraulic fluid source and the torque-transmitting mechanisms. It mediates pressure distribution and enables centralized control of multiple clutches/brakes through a single valve, simplifying the control architecture despite the increased number of ranges
2Adaptability or versatility
If more torque-transmitting mechanisms are added to achieve more ranges, then the adaptability is improved, but the reliability decreases due to more potential failure points and difficulty in ensuring correct clutch engagement
Solution Approach 1:
The boost valve provides inherent feedback functionality through its response to hydraulic pressure conditions. It monitors the state of torque-transmitting mechanisms and automatically responds to pressure changes, enabling fault detection and ensuring correct engagement states without requiring additional complex sensing systems
Solution Approach 2:
The system incorporates default range functionality that activates upon detection of electrical power loss or faults. This preparatory measure ensures the transmission automatically shifts to a safe default range, cushioning against potential failures before they cause damage or unsafe operation
3Adaptability or versatility
If the control system is made more complex to manage more ranges, then the adaptability is improved, but the ease of operation decreases due to difficulty in managing correct clutch engagement
Solution Approach 1:
The boost valve combines multiple control functions into a single hydraulic control element. It integrates pressure regulation, clutch/brake engagement control, and fault response capabilities, reducing the number of separate control actions required and simplifying the overall control operation despite managing multiple ranges
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
The system effectively controls a multispeed transmission across various ranges, ensuring correct clutch engagement and fault tolerance, even in power loss scenarios, by precisely managing hydraulic pressures and clutch states, thereby enhancing transmission performance and reliability.
Implementation Method 1
a first shift solenoid disposed in electrical communication with the controller, the first shift solenoid being operably controlled between an energized and de-energized states to control movement of the first and second shift valves; a second shift solenoid disposed in electrical communication with the controller, the second shift solenoid being operably controlled between an energized and de-energized states to control movement of the third shift valve
Implementation Method 2
a fluid source for supplying hydraulic fluid; a plurality of torque-transmitting mechanisms being operably selected between an applied and an unapplied state to achieve a plurality of ranges
Data Source
AI summary
An electro-hydraulic control system for a multispeed transmission having a plurality of torque-transmitting mechanisms includes a controller for operably controlling the transmission, a fluid source for supplying hydraulic fluid, and a plurality of torque-transmitting mechanisms being operably selected between an applied and an unapplied state to achieve a plurality of ranges including at least one reverse, a neutral, and a plurality of forward ranges. The system includes a plurality of trim systems having pressure control solenoids and trim valves. The system may also include one or more shift valves disposed in fluid communication with the fluid source and being capable of moving between stroked and de-stroked positions. In any given range, only two of the plurality of torque-transmitting mechanisms may be applied. Moreover, three of the plurality of pressure control solenoids are normally high solenoids, and the remaining solenoids are normally low solenoids.