Electric Pump Drain Valve for Hydraulic Pressure Control
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Solution Overview
Problem
In power transmission devices, oil leakage from high-pressure passages can lead to unexpectedly high hydraulic pressures due to the absence of a drain mechanism in electromagnetic pumps, causing operational inefficiencies and potential damage.
Innovation Solution
Incorporating a switching mechanism with a drain valve that connects the electric pump oil passage to a drain oil passage when the switching mechanism shuts off communication between the electric pump and hydraulic servo, maintaining appropriate hydraulic pressure by draining excess oil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a switching mechanism shuts off the oil passage between the electric pump and hydraulic servo, then the hydraulic servo can be isolated for precise control, but oil leakage from adjacent high-pressure passages causes excessive pressure buildup in the closed electric pump oil passage
Solution Approach 1:
A drain valve is introduced as an intermediary component in the electric pump oil passage. This drain valve selectively opens to drain excess oil to the reservoir when excessive pressure is detected, and closes to maintain pressure when needed. The drain valve thus mediates between the need for pressure isolation (for control precision) and the need to prevent excessive pressure buildup (harmful factor), resolving the contradiction by providing conditional pressure relief.
2Object-affected harmful factors
If the electromagnetic pump is equipped with a drain mechanism, then excessive pressure can be prevented, but the device complexity and potential for oil leakage increase
Solution Approach 1:
The drain valve is designed to automatically respond to pressure conditions without external control. When excessive pressure builds up in the electric pump oil passage, the drain valve self-activates to drain oil, and when pressure is appropriate, it self-closes to maintain pressure. This self-service mechanism prevents excessive pressure without requiring complex external control systems, resolving the contradiction between pressure prevention and device complexity.
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 regulates hydraulic pressure in the electric pump oil passage, preventing excessive pressure buildup and ensuring smooth operation by draining excess oil, thus preventing operational inefficiencies and potential damage.
Implementation Method 1
a drain valve that opens to drain oil when a hydraulic pressure of a preset pressure or more is applied
Implementation Method 2
a spool that allows and shuts off communication between the first input port and the drain port, and an urging member that urges the spool. In the power transmission device, the switching mechanism may be structured so as to allow communication between the first input port and the drain port by moving the spool to one end side by a hydraulic pressure of the preset pressure or more
Data Source
AI summary
A power transmission device that transmits power from a motor to a wheel via a hydraulically driven friction engagement element and that includes a mechanical pump driven by the motor to produce a hydraulic pressure that is regulated by a pressure regulating valve; an electric pump that produces a hydraulic pressure; a switching mechanism that either switches an output pressure of the regulating valve or an output pressure of the electric pump to a servo of the engagement element based upon a signal pressure, and a drain valve that opens to drain oil when a hydraulic pressure of a preset pressure or more is applied, and the switching mechanism connects to the drain valve to allow communication between the electric pump and the drain valve in the first state, and shut off communication between the electric pump and the drain valve.