Pulsed Fluid Release Device for Automatic Transmission Start-Stop
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Solution Overview
Problem
Existing devices for pulsed release of fluid in automatic transmissions are complex, space-intensive, and inefficient, particularly in implementing start-stop functions, as they require significant design effort and additional installation space due to reliance on electric motor-driven hydraulic pumps.
Innovation Solution
A device featuring a seat valve with a pilot-operated check valve and an electromagnetically actuated valve, which allows controlled filling and leak-free control of fluid release, minimizing deflection losses and enabling quick fluid release, is integrated into the accumulator housing, with a hollow piston design to maximize storage volume and reduce structural complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an electric motor-driven hydraulic pump is used to compensate clutch play and enable start-stop function, then the transmission can operate during engine shutdown, but the transmission efficiency deteriorates and the system becomes more expensive with increased installation space
Solution Approach 1:
The invention extracts the essential function of fluid delivery from the complex electric motor-driven pump system and implements it through a simplified mechanical arrangement using a piston, check valve, and accumulator housing. This removes the unnecessary electric motor and control system while retaining the core capability to deliver hydraulic fluid for clutch play compensation during start-stop operation.
Solution Approach 2:
The system uses the kinetic energy of the moving piston to automatically deliver hydraulic fluid to the clutch without requiring an external power source. The piston's motion during transmission operation naturally drives the check valve open and forces fluid into the clutch chamber, eliminating the need for an electric motor-driven pump and its associated control systems.
2Productivity
If a conventional fluid supply device is used, then the structure is simple, but the clutch play cannot be compensated quickly enough when the engine restarts after shutdown
Solution Approach 1:
The system pre-positions the piston and stores hydraulic fluid in the accumulator housing during normal operation, so that when clutch engagement is required during start-stop operation, the fluid is already available and can be delivered immediately. This preliminary preparation eliminates the time delay associated with pumping fluid from scratch when the engine restarts.
Solution Approach 2:
The system operates in periodic cycles: during normal engine operation, the piston moves to store fluid in the accumulator; when the engine shuts down and needs to restart, the piston reverses and delivers the stored fluid quickly to the clutch. This periodic charging and discharging enables rapid response without requiring a complex high-speed pump system.
3Quantity of substance
If the accumulator housing volume is maximized to store sufficient fluid for quick clutch engagement, then the fluid availability improves, but the installation space requirement increases
Solution Approach 1:
The invention combines the accumulator housing with the piston assembly into a single integrated unit. The piston itself becomes part of the fluid storage system, with fluid being stored in the annular space between the piston and the accumulator housing wall. This merging eliminates the need for a separate large-capacity accumulator while still providing sufficient fluid storage for rapid clutch engagement.
Solution Approach 2:
The system changes the operational parameters of fluid delivery by using high-pressure fluid from the piston's motion rather than relying on large-volume low-pressure storage. This allows sufficient fluid quantity to be delivered in a compact space by increasing the pressure parameter, enabling the same clutch engagement function with a much smaller accumulator housing volume.
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 a simple, robust, and wear-resistant mechanism for pulsed fluid release, ensuring reliable engine start-stop operations with short control times and reduced space requirements, enhancing transmission efficiency and fuel consumption reduction.
Implementation Method 1
The first energy store (4), which is designed as a compression spring (18), acts on the piston (5) with a force
Implementation Method 2
the check valve (10) which is built in blocking the filling direction of the accumulator housing (2)
Implementation Method 3
provision is made for the valve device (6) to be in the form of an electromagnetically actuated valve
Data Source
Figure 1
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Figure 3
AI summary
The invention relates to a device for releasing in a pulsed manner a fluid amount (3) that can be stored in an accumulator housing (2), in particular for carrying out a start-stop function in automatic transmissions, comprising a piston (5) supported against a first energy store (4), which piston can be moved inside the accumulator housing (2) and together with said housing (2) limits the fluid amount (3) that can be accommodated, wherein the piston (5) is held by a valve unit (6) at least in a position equivalent to the maximum volume of the fluid amount (3) in the accumulator housing (2) in that a fluid-conducting connection (7) between the accumulator housing (2) and a load (8) is blocked by the valve unit (6), said device for releasing in a pulsed manner the fluid amount (3) that can be stored in the accumulator housing (2) being characterized in that the valve unit (6) is made up of at least one seat valve (9).