Hydraulic Pump Power Distribution in Automatic Transmissions
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Solution Overview
Problem
Automatic transmission hydraulic medium supply systems often lack system pressure during certain vehicle operating modes, preventing gear tracking and clutch filling due to separate hydraulic pump circuits that cannot support each other.
Innovation Solution
A method for controlling hydraulic fluid supply systems in automatic transmissions, using a back-up valve to adjust power distribution between engine-side and wheelset-side hydraulic pumps based on detected vehicle parameters, ensuring consumption-optimized operation by activating different switching positions for various operating modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate hydraulic pump circuits are used for engine-side system pressure generation and wheelset-side cooling, then structural independence and specialized function are achieved, but mutual support between pumps is lost and system pressure is insufficient during certain operating modes
Solution Approach 1:
The patent merges the previously separate hydraulic pump circuits into a unified system where both the engine-driven hydraulic pump and the wheelset-driven hydraulic pump can contribute to a common hydraulic medium supply circuit. This allows the pumps to support each other and maintain system pressure during coasting operations or when the engine is not running.
Solution Approach 2:
The hydraulic pumps are designed to perform multiple functions: the engine-driven pump can provide system pressure during normal operation, while the wheelset-driven pump can take over or supplement pressure generation during coasting modes. The system allows either pump to serve both pressure generation and cooling functions depending on operating conditions.
2Reliability
If hydraulic pumps operate continuously to maintain system pressure, then pressure availability is ensured, but energy consumption increases
Solution Approach 1:
The control system dynamically adjusts the operation of hydraulic pumps based on detected vehicle parameters and operating modes. During coasting operations or when system pressure is sufficient, the engine-driven pump can be deactivated or operated at reduced delivery, allowing the wheelset-driven pump to maintain pressure alone, thereby reducing overall energy consumption while ensuring pressure availability when needed.
Solution Approach 2:
The system changes operational parameters of the hydraulic pumps based on operating conditions. The control unit monitors vehicle state and adjusts pump delivery rates, activation states, and pressure setpoints to optimize the balance between pressure maintenance and energy consumption across different driving scenarios.
3Reliability
If the engine-driven hydraulic pump operates at high delivery to maintain system pressure, then pressure sufficiency is achieved, but energy consumption and losses increase
Solution Approach 1:
Instead of requiring the engine-driven hydraulic pump to operate at full delivery continuously, the system uses partial action by allowing the wheelset-driven hydraulic pump to provide sufficient pressure during coasting modes. The engine-driven pump operates at reduced delivery or remains inactive during these periods, eliminating excessive energy consumption while maintaining adequate system pressure through the combined capability of both pumps.
Data Source
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AI summary
A method for actuating a hydraulic medium supply system of an automatic transmission of a vehicle is proposed, wherein the hydraulic medium supply system is supplied with hydraulic medium at least by a hydraulic pump (FZP-Pu) driven by the engine and by a hydraulic pump (RS-Pu) driven by the wheelset. According to the invention, a check valve of the hydraulic medium supply system for supplying hydraulic medium as a function of detected vehicle parameters is actuated to set a suitable power distribution at the hydraulic pumps (FZP-Pu, RS-Pu).