Transmission Hydraulic Control System with Two-Pass Torque Converter
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hydraulic control systems for automatic transmissions face challenges in maintaining efficient operation and fuel efficiency, particularly when the engine is shut off, as they require continuous fluid circulation for lubrication and torque converter functions, which can lead to inefficiencies and potential errors in clutch engagement and disengagement.
Innovation Solution
A two-pass torque converter assembly with a single regulator valve that controls fluid flow among pressure supply, apply, release, and lubrication circuits, using a spool valve design to manage pressure differentials and prevent stuck valve errors, ensuring consistent fluid flow and torque capacity based on pressure differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine is shut off to reduce fuel consumption, then fuel efficiency is improved, but continuous fluid circulation for lubrication and torque converter functions cannot be maintained
Solution Approach 1:
The hydraulic control system is segmented into multiple independent circuits: a first hydraulic circuit for lubrication that can operate independently, and a second hydraulic circuit for torque converter clutch control. This segmentation allows the lubrication circuit to maintain fluid circulation even when the engine is shut off, while the torque converter circuit can be controlled separately to enable start-stop functionality.
Solution Approach 2:
The regulator valve is designed to perform multiple functions: controlling lubrication fluid flow, managing torque converter clutch engagement/disengagement, and operating in both engine-on and engine-off modes. This multi-functionality allows a single component to maintain system reliability across different operational states without requiring separate dedicated systems.
2Device complexity
If a single regulator valve is used to control multiple functions, then device complexity is reduced, but the risk of stuck valve errors increases
Solution Approach 1:
The system incorporates feedback mechanisms where the controller monitors the operational state of the regulator valve and can detect stuck valve conditions. Based on this feedback, the controller can command transitions between operational modes (engine-on/engine-off) to prevent or correct stuck valve errors, thereby maintaining reliability despite using a single valve.
Solution Approach 2:
The regulator valve is designed to operate across different pressure and flow parameters depending on the operational mode. By changing operational parameters (such as fluid pressure levels and flow rates) based on whether the engine is on or off, the system can prevent the valve from sticking in any single position, reducing the risk of errors while maintaining simplicity.
3Reliability
If fluid pressure is increased to ensure reliable clutch engagement, then clutch engagement reliability is improved, but energy consumption and heat generation increase
Solution Approach 1:
The regulator valve dynamically adjusts fluid pressure based on real-time operational requirements. During clutch engagement, pressure is increased only to the necessary level and for the necessary duration, then reduced. This dynamic pressure adjustment ensures reliable clutch engagement while minimizing energy loss and heat generation that would result from continuously high pressure.
Solution Approach 2:
The system uses periodic fluid circulation and pressure application rather than continuous high pressure. The regulator valve periodically supplies fluid to the torque converter clutch circuit only when engagement or disengagement is required, reducing overall energy consumption while maintaining clutch engagement reliability when needed.
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 solution enables efficient clutch engagement and disengagement, maintains lubrication, and prevents errors by ensuring consistent fluid flow and torque capacity, even when the engine is shut off, enhancing fuel efficiency and reducing the risk of transmission errors.
Implementation Method 1
a hydro-dynamic chamber fluid coupling that draws fluid from a release circuit and exhausts fluid to an apply circuit when release circuit pressure exceeds the apply circuit pressure
Implementation Method 2
A torque converter regulator valve includes a housing and a spool configured to slide within the housing. The housing defines a number of ports including a pressure supply port, a first apply port, a first vent, a release port, a feed port, a lubrication port, a second apply port, and a control port.
Implementation Method 3
A spring biases the spool toward one end of the housing such that a first of the four lands blocks the pressure supply port and the first apply port
Implementation Method 4
Pressure in the control port biases the spool toward the opposite end of the housing such that the first chamber fluidly connects the pressure supply port to the first apply port
Implementation Method 5
When the apply circuit pressure exceeds the release circuit pressure, a bypass clutch transmits torque with a torque capacity based on the pressure difference
Data Source
AI summary
An automatic transmission uses 6 shift elements applied in combinations of four to establish ten forward speed ratios and a reverse speed ratio. The automatic transmission uses a hydraulic control system to control engagement of the six elements, control engagement of a torque converter bypass clutch, control engagement of a parking pawl, and to provide fluid for a hydrodynamic torque converter and for lubrication. The parking pawl is disengaged in response to engagement of two of the six shift elements and remains disengaged in response to engagement of other shift elements. A single valve controls several different functions associated with the two-pass torque converter. Pressurized fluid is provided by a variable displacement engine driven pump and also by an electric pump. A priority valve reduces lubrication flow when other fluid demands are high as indicated by the pump displacement control circuit.