Hydraulic Control Unit Drainage Management
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Solution Overview
Problem
The existing hydraulic pressure circuit for automatic transmissions with idle stop control mechanisms wastes energy and increases the capacity of the electrically-operated oil pump by unnecessarily draining discharge oil, leading to excessive load and power consumption when the engine is automatically shut down.
Innovation Solution
A hydraulic control unit with a selector valve that controls the drainage of discharge oil from the electrically-operated oil pump, reducing unnecessary drainage when the selector valve is in the second state, thereby minimizing the load and size of the electric pump and optimizing hydraulic pressure supply to frictional engagement elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the drain line is provided to prevent discharge oil from being trapped in the discharge line, then the excessive load on the electric pump is reduced, but unnecessary draining occurs even when the selector valve is in the second position, leading to increased power consumption and pump capacity
Solution Approach 1:
The drain line is blocked by the spool of the selector valve before the electric pump starts operating, preventing unnecessary draining. When the electric pump is activated, the spool moves to the second position and unblocks the drain line, allowing discharge oil to be drained only when needed. This preliminary blocking action eliminates wasteful energy consumption while maintaining the ability to prevent excessive load.
Solution Approach 2:
The drain line's openness is dynamically controlled by the position of the selector valve's spool. When the spool is in the first position, the drain line is blocked; when the spool moves to the second position, the drain line opens. This dynamic control ensures that the drain line serves its protective function only when necessary, optimizing power consumption.
2Reliability
If the drain line continuously drains discharge oil to prevent trapping, then the electric pump durability is improved, but the pump capacity and size must be increased to handle the continuous draining
Solution Approach 1:
The drain line is preliminarily blocked by the selector valve's spool before the electric pump operates. This prevents continuous draining that would require a larger pump capacity. The drain line is activated only when needed, allowing the use of a smaller, more compact pump while maintaining durability through targeted draining when the spool moves to the second position.
3Adaptability or versatility
If the selector valve switches to the second position during engine shutdown, then the electric pump becomes the hydraulic pressure supply source, but the drain line causes unnecessary energy waste by continuing to drain discharge oil
Solution Approach 1:
The drain line's state is dynamically linked to the selector valve's position. When the selector valve switches to the second position during engine shutdown, the spool moves accordingly and blocks the drain line, preventing unnecessary energy loss. The drain line opens only when the spool is in the first position, ensuring that energy is not wasted during the critical shutdown period when the electric pump is the sole supply source.
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 configuration reduces energy loss, prevents excessive load on the electric pump, and decreases power consumption by efficiently managing hydraulic pressure during engine shutdown, maintaining the engaged state of frictional engagement elements without increasing the pump's capacity.
Implementation Method 1
a drain line (660) having a flow rate restricting orifice (662)
Implementation Method 2
the spool 622 of the selector valve 620 is movable between a first position at which the mechanical pump 606 is the hydraulic pressure supply source, and a second position at which the electric pump 616 is the hydraulic pressure supply source
Implementation Method 3
the elastic force of a return spring 640 causes the spool 622 to be located at the second position
Data Source
AI summary
A hydraulic control unit for an automatic transmission has a mechanically-operated oil pump (6), an electrically-operated oil pump (106) actuated while an engine (2) is automatically shut down, and a hydraulic pressure circuit (100) which controls supply of hydraulic pressure to a frictional engagement element (40, 60) to be engaged, in the automatic transmission, at a vehicle's start. In the hydraulic pressure circuit, discharge oil from the electrically-operated oil pump is drained from a predetermined drain portion (154) when a selector valve (120) is in the first state (in which the mechanically-operated oil pump is a source of the supply of the hydraulic pressure to the frictional engagement element), whereas less discharge oil is drained from the drain portion, compared to the first state, when the selector valve (120) is in the second state (in which the electrically-operated oil pump is the source of the supply of the hydraulic pressure).