Electrohydraulic Pump Pressure Control With Mechanical Overpressure Stop
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Solution Overview
Problem
Existing variable displacement pumps face challenges in precise control of displacement, particularly in response to abrupt hydraulic pressure changes and potential electronics failures, which can lead to system instability and damage.
Innovation Solution
A pump control assembly featuring a spool valve with spring-loaded chambers and a proportional pressure reducing valve, controlled by a solenoid, that adjusts the swash plate angle to manage pump displacement, incorporating a mechanical stop to prevent over-pressurization and eliminate the need for a separate pressure compensator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate pressure compensator device is included to safeguard against pressure fluctuations and electronics failure, then system safety is improved, but device complexity increases
Solution Approach 1:
The patent combines the pressure compensator function with the existing spool valve assembly by integrating a second spring and stop structure directly into the valve block. This merging eliminates the need for a separate pressure compensator device while maintaining safety functions, thereby reducing device complexity without compromising reliability
Solution Approach 2:
The spool valve assembly is designed to perform multiple functions: primary displacement control through the first spring, and secondary pressure compensation through the second spring and stop structure. This multi-functionality allows a single component to provide both control and safety functions, reducing the overall number of components needed in the system
2Adaptability or versatility
If customized real time control of pump displacement is implemented using solenoids, then adaptability is improved, but vulnerability to electronics failure increases
Solution Approach 1:
The patent introduces a mechanically-based pressure compensator system that acts as an intermediary safety mechanism between the electronic control system and the hydraulic circuit. This mechanical backup provides a fail-safe pressure limitation function that operates independently of the electronic solenoid control, thereby improving reliability without sacrificing real-time control capability
Solution Approach 2:
The second spring and stop structure are pre-configured to provide pressure compensation and limit maximum system pressure before electronics failure can cause damage. This beforehand cushioning ensures that even if the electronic control system fails, the mechanical components will prevent dangerous pressure buildup, thereby improving system reliability
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
Provides precise, step-less control of pump displacement, enhancing system stability and preventing damage from pressure fluctuations, while integrating safety mechanisms to safeguard against controller failures.
Implementation Method 1
A pump control assembly featuring a spool valve with spring-loaded chambers and a proportional pressure reducing valve, controlled by a solenoid
Implementation Method 2
The second chamber also includes a piston and first and second springs positioned on either side of the piston
Implementation Method 3
the pressure from the hydraulic tank and the pressure from the hydraulic circuit are typically considered
Data Source
AI summary
A pump control assembly for controlling a variable displacement hydraulic pump includes a spool mounted within a valve block. The spool is configured to move between a first and a second position within the valve block so as to selectively control the displacement of the attached pump. The pump control assembly further includes first and second chambers that each apply a force to opposite ends of the spool. The first chamber is positioned at a first end of the spool in fluid communication with a pump output port. The second chamber is positioned at a second end of the spool and in fluid communication with a hydraulic tank port and a proportional pressure reducing valve. The second chamber also includes a piston and first and second springs positioned on either side of the piston. The proportional pressure reducing valve provides a regulated pressure to a first side of the piston along with the first spring, and the hydraulic tank port provides a tank pressure on the opposite side of the piston along with the second spring. The pump control assembly also includes a stop structure having a positive stop that limits movement of the piston in a direction toward the first chamber.