Power Transmission Device Neutral Shift Draining Mechanism
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Solution Overview
Problem
Existing power transmission devices fail to prevent unexpected power transmission to the axle when an abnormality, such as foreign matter penetration, causes the selector valve to stick, leading to residual hydraulic pressure being trapped and power transmission during neutral shifts.
Innovation Solution
A power transmission device incorporating a mechanical pump, a switching valve, a shift valve, and an electric pump that ensures fluid pressure is drained from the friction engagement element during neutral shifts, even if the switching valve is stuck, using a solenoid valve that functions as both a pressure regulating valve and an electromagnetic pump to manage fluid pressure effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the switching valve is used to control fluid pressure to the friction engagement element, then the device complexity is reduced, but the reliability deteriorates because the valve may stick due to foreign matter penetration causing unexpected power transmission
Solution Approach 1:
The patent divides the single switching valve system into two separate components: a shift valve for controlling fluid pressure during normal operation, and a drain valve for draining fluid pressure during neutral shifts. This segmentation ensures that if one valve sticks, the other can still function to prevent unexpected power transmission, thus improving reliability while maintaining reasonable device complexity.
Solution Approach 2:
The patent implements a preliminary draining mechanism that activates during neutral shifts to drain fluid pressure from the friction engagement element before power transmission can occur. This preliminary action prevents the harmful effect of stuck valves by ensuring pressure is removed in advance, resolving the contradiction between simplified valve control and reliable power transmission prevention.
2Use of energy by moving object
If the mechanical pump is stopped during neutral shifts, then energy consumption is reduced, but the reliability deteriorates because residual pressure cannot be drained
Solution Approach 1:
The patent extracts the draining function from the mechanical pump by implementing a separate drain valve mechanism that operates independently during neutral shifts. This allows the mechanical pump to remain stopped and conserve energy, while the drain valve specifically handles pressure removal to maintain reliability, resolving the contradiction between energy consumption and reliable control.
3Productivity
If the friction engagement element is rapidly engaged after restart, then productivity is improved, but the reliability deteriorates because residual pressure may cause unexpected power transmission
Solution Approach 1:
The patent implements preliminary draining of fluid pressure during the neutral shift phase before restart occurs. This preliminary action ensures that when the friction engagement element engages rapidly after restart, there is no residual pressure to cause unexpected power transmission, thus resolving the contradiction between rapid response and reliable control.
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 effectively suppresses unexpected power transmission to the axle during neutral shifts by ensuring fluid pressure is drained, preventing unintended power transfer and allowing rapid engagement of the friction engagement element when the system restarts.
Implementation Method 1
a mechanical pump that is driven by power from the motor and generates fluid pressure
Implementation Method 2
an electromagnetic pump that directly delivers discharge pressure to the clutch
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A manual valve is formed with a drain input port that closes if a shift is made to the D position, and opens for draining if a shift is made to the N position. A switching valve communicates an output port of a pressure regulating valve portion and an oil passage of a clutch and closes a drain port during engine operation when a line pressure is applied, and cuts off communication between the output port of the pressure regulating valve portion and the oil passage of the clutch and communicates the oil passage with the drain port during an engine automatic stop when the line pressure is not applied. The drain input port and the drain port are connected by a drain oil passage.