Hydraulic Control Device for Automatic Transmission Shocks
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Solution Overview
Problem
In hydraulic control devices for automatic transmissions, the use of a shuttle valve can lead to unexpected shocks due to re-engagement of engagement elements when a solenoid valve fails, causing the third clutch to remain engaged during shifts, especially when switching from N-range or R-range to the first forward speed.
Innovation Solution
A hydraulic control device with a solenoid valve, pressure regulating valve, switching valve, and control unit that blocks the supply of the first source pressure to the third engagement element during shifts from the first shift speed to the second shift speed, even if the solenoid valve is in a failure state, by using a switching valve with a valving element that moves based on signal pressures to prevent communication between input ports of different pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a shuttle valve is used to switch between forward range pressure and reverse range pressure, then the hydraulic control device can enable smooth shifting between ranges, but the third clutch may remain engaged due to source pressure supply when a solenoid valve fails in a fixed open state
Solution Approach 1:
A blocking valve is introduced as an intermediary component between the shuttle valve and the third clutch. This blocking valve acts as a mediator that can interrupt the source pressure supply path, preventing unintended clutch engagement while maintaining the normal pressure switching function of the shuttle valve during successful operations
Solution Approach 2:
The blocking valve proactively blocks the source pressure supply to the third clutch before unintended engagement can occur. By anticipating the potential failure mode of the solenoid valve, the system preemptively prevents the harmful effect of clutch re-engagement during range switching operations
2Productivity
If a linear solenoid valve supplies and discharges engagement pressure to an engagement element during speed change, then the engagement element can be switched from engaged to disengaged state, but re-engagement may occur before disengagement is complete due to source pressure supply via shuttle valve
Solution Approach 1:
The blocking valve serves as an intermediary that controls the source pressure supply to the linear solenoid valve. It ensures that pressure is supplied only after the engagement element has fully disengaged, preventing premature re-engagement while maintaining efficient speed change operation
Solution Approach 2:
The system performs preliminary disengagement of the engagement element before supplying source pressure through the blocking valve. This sequencing ensures that the engagement element is fully disengaged before pressure is applied, preventing re-engagement issues during speed changes
3Adaptability or versatility
If the third clutch is engaged at reverse speed and disengaged at first forward speed, then the transmission can switch between reverse and forward ranges, but unexpected shock may be generated if simultaneous engagement occurs during failure state
Solution Approach 1:
The blocking valve acts as a protective intermediary that prevents harmful simultaneous engagement of the third clutch and second brake. By controlling the source pressure supply timing, it eliminates the shock-generating condition while preserving the normal range switching functionality
Solution Approach 2:
The system converts the potential harmful effect of solenoid valve failure into a beneficial protective function. The blocking valve's failure-safe blocking action, which normally prevents unintended engagement, becomes the mechanism that eliminates shock by ensuring proper sequencing even when other components fail
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 prevents the supply of the first source pressure to the solenoid valve for the third clutch, ensuring smooth shifts without unexpected shocks or engagement of multiple elements simultaneously, even in case of solenoid valve failure.
Implementation Method 1
a valving element that is movably allocated between the first input port and the second input port, moves to an input port side of a source pressure with a lower pressure between the first source pressure (PD, PEMOP) and the second source pressure (PR), blocks communication between the input port of the source pressure with the lower pressure and the output port, establishes communication between an input port of a source pressure with a higher pressure and the output port
Implementation Method 2
a solenoid valve capable of supplying an engagement pressure to the second engagement element
Implementation Method 3
a pressure regulating valve capable of supplying a first signal pressure
Data Source
AI summary
A hydraulic control device is provided with a solenoid valve, a pressure regulating valve, a switching valve, and a control unit. The control unit, when shifting from a first shift speed to a second shift speed, causes a first signal pressure to be input to an oil chamber of the switching valve with the pressure regulating valve, and presses a valving element to a first input port side to be locked at a blocking position at which communication between the first input port and an output port is blocked at least until a third engagement element is brought into an engaged state from a disengaged state.