Hydraulic Control Circuit for Hybrid Powertrain Clutch Actuation
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Solution Overview
Problem
Current hydraulic control circuits for hybrid powertrains are complex and lack a simpler, more elegant solution for precise control of clutch actuation and cooling in hybrid vehicles, which affects the efficiency and comfort of vehicle propulsion.
Innovation Solution
A hydraulic control circuit comprising a first and second pressure regulating valve, a shift valve, and a check valve, with specific fluid pathways and electro-mechanical actuators, enabling selective communication of pressurized hydraulic fluid to the clutch actuator and cooling circuit, and a fail-safe mode to ensure vehicle propulsion by the engine in case of circuit failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a complex hydraulic control circuit is used to achieve precise control of clutch actuation and cooling, then control precision is improved, but device complexity increases
Solution Approach 1:
The patent combines the clutch actuation control and cooling circuit control into a single integrated hydraulic control circuit. The first and second pressure regulating valves share a common control input from the control module, and the hydraulic fluid serves dual purposes: actuating the clutch piston and cooling the electric motor through the cooling circuit. This merging reduces the number of separate control systems while maintaining precise control over both functions.
Solution Approach 2:
The hydraulic control circuit is designed with multi-functionality where the same hydraulic fluid pathway and control mechanism serve multiple purposes. The pressure regulating valves control both clutch engagement and cooling fluid flow, and the hydraulic system can operate in different modes (clutch actuation mode, cooling mode, or both simultaneously) based on control signals, reducing overall system complexity.
2Temperature
If transmission fluid is cycled through the cooling circuit to cool the electric motor and clutch assembly, then thermal energy is dissipated, but transmission efficiency decreases due to energy usage and demand on transmission fluid
Solution Approach 1:
The cooling circuit operates periodically rather than continuously. The control module activates the cooling function only when thermal energy accumulation is detected or anticipated (during clutch engagement or electric motor operation), allowing the transmission fluid to be cycled through the cooling circuit intermittently. This periodic operation reduces the overall demand on transmission fluid and minimizes energy loss while still achieving effective thermal dissipation when needed.
Solution Approach 2:
The hydraulic system serves itself by using the same transmission fluid that powers the clutch actuation to also perform cooling duties. The system monitors its own thermal state and automatically activates cooling when required, eliminating the need for separate cooling pumps or external cooling systems that would increase energy consumption and reduce transmission efficiency.
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 solution provides precise control of the clutch assembly, maintains vehicle propulsion efficiency, and ensures a fail-safe mode to prevent disturbances to vehicle occupants, enhancing the overall performance and reliability of hybrid powertrains.
Implementation Method 1
a first pressure regulating valve configured to cooperate with the shift valve for selectively communicating a pressurized hydraulic fluid to the hydraulic actuator
Implementation Method 2
A hydraulic cooling control system is utilized to cool the electric motor to maintain desired motor efficiency and to cool the thermal energy generated by the actuation and modulation of the clutch assembly
Implementation Method 3
a check valve in hydraulic communication with the first pressure regulating valve, the second pressure regulating valve, and the shift valve
Data Source
AI summary
A hydraulic circuit for a hybrid powertrain having an engine and an electric motor. The hydraulic control circuit includes a first pressure regulating valve configured to cooperate with a shift valve for selectively communicating a hydraulic fluid to a hydraulic piston actuator of a clutch assembly for engaging the engine to a driveline. The hydraulic control circuit further includes a second pressure regulating valve configured to selectively communicate a flow of hydraulic fluid to a cooling circuit for the cooling of the electric motor and to cooperate with a check valve and the shift valve to actuate the hydraulic piston actuator during a predetermined fail mode of the first pressure regulating valve, thus providing a limp-home mode by coupling the torque output from the engine to driveline of the vehicle.