Hydraulic Control Device Preventing Valve Over-stroke via Pilot Pressure
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Solution Overview
Problem
The existing hydraulic control devices face issues with over-stroking of the valve body in the pressure control valve when the rotational speed of the electric motor exceeds the appropriate speed, leading to a decrease in hydraulic pressure, and this is typically addressed by incorporating a hydraulic pressure sensor and control circuit, which increases costs.
Innovation Solution
A hydraulic control device configuration that includes a mechanical oil pump, an electric oil pump, and a pressure control valve with specific port arrangements and flow passages, where the valve body is moved by a pilot pressure to prevent over-stroking without the need for a hydraulic pressure sensor or control circuit, allowing the oil flow to be released and maintaining hydraulic pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hydraulic pressure sensor and control circuit are incorporated to control the rotation of the electric motor, then the over-stroke condition can be suppressed, but the costs increase
Solution Approach 1:
The pressure control valve uses its own outlet pressure (pilot pressure) to control its own valve body position. When the electric oil pump rotates too fast and outlet pressure rises, the pilot pressure automatically moves the valve body to open the second supply port, releasing pressure without needing external sensors or control circuits.
Solution Approach 2:
The system establishes a feedback loop where the outlet pressure of the electric oil pump is fed back to the pilot pressure port of the pressure control valve. This feedback mechanism automatically adjusts the valve body position based on the actual pressure condition, preventing over-stroke when the electric motor rotates faster than appropriate.
2Productivity
If the rotational speed of the electric motor exceeds the appropriate speed, then the oil pump can supply more hydraulic pressure, but the valve body over-strokes and hydraulic pressure decreases
Solution Approach 1:
The pressure control valve dynamically adjusts its flow passage configuration based on the operating conditions. When the electric oil pump rotates too fast, the valve body automatically moves to change the flow path, opening the second supply port to release excess pressure and maintain stable hydraulic pressure delivery to the transmission.
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 effectively prevents the valve body from moving beyond its specified stroke, maintains hydraulic pressure, and eliminates the need for additional sensors and control circuits, reducing costs while maintaining efficient operation.
Implementation Method 1
a valve body which is moved by a pilot pressure supplied from a third supply port
Implementation Method 2
When the rotational speed of the electric motor exceeds the appropriate rotational speed, the valve body is in a second position, in which the second supply port and the first discharge port are placed in communication
Data Source
AI summary
In a hydraulic control device, when the rotational speed of an electric motor is an appropriate rotational speed, a first spool is in a first position, in which communication between a sixth port and a second port is blocked. When the rotational speed of the electric motor exceeds the appropriate rotational speed, the first spool is in a second position, in which the sixth port and the second port are placed in communication.