Load-Sensing Hydraulic Distributor With Active Discharge Heating
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Solution Overview
Problem
Closed-center hydraulic distributors in agricultural applications, such as front loader vehicles, experience uneven temperature distribution leading to potential blocking of the distribution spool due to thermal expansion differences, posing safety risks during initial actuations.
Innovation Solution
A bi-directional, two-position pilot-operated slide valve with spring and pressure-actuated active areas is introduced to minimize temperature differentials by allowing controlled oil flow through the distributor, even when no utility is actuated, and a secondary connection to the low-pressure line to prevent LS pressure trapping, enabling efficient heating and reduced power dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a closed-center hydraulic distributor is used to maintain system pressure, then power loss is reduced, but uneven temperature distribution occurs causing spool blocking
Solution Approach 1:
The patent extracts the heating function from the main hydraulic circuit by introducing a separate bypass circuit with a heating valve. This allows the distributor body to be heated independently without affecting the main closed-center pressure maintenance function, thereby eliminating spool blocking while preserving energy efficiency.
Solution Approach 2:
The patent introduces a heating oil circuit as an intermediary system. Heating oil circulates through the distributor body via a dedicated bypass circuit, acting as a mediator to transfer thermal energy uniformly throughout the distributor without interfering with the main hydraulic fluid's pressure maintenance function.
2Temperature
If a bypass valve is added to heat the distributor, then temperature uniformity improves, but device complexity increases
Solution Approach 1:
The patent merges the heating function with the existing hydraulic circuit by using the same hydraulic fluid to serve dual purposes: maintaining system pressure and providing heating when circulated through the bypass circuit. This eliminates the need for separate heating systems and reduces overall complexity.
Solution Approach 2:
The hydraulic fluid in the system performs multiple functions: it maintains system pressure in the closed-center circuit and provides thermal energy for heating the distributor body when routed through the bypass circuit. This multi-functionality reduces the need for additional dedicated heating components.
3Temperature
If heating oil flows through the distributor, then even heating is achieved, but power dissipation increases
Solution Approach 1:
The patent implements periodic heating cycles where the bypass valve opens only when temperature sensors detect that the distributor body temperature has dropped below a threshold. The heating oil circulates for a predetermined time or until the temperature threshold is reached, then the valve closes. This periodic action minimizes energy dissipation while ensuring adequate heating.
Solution Approach 2:
The system uses the existing thermal energy in the hydraulic fluid to heat the distributor body. The bypass circuit allows the hydraulic fluid to serve its own heating function, eliminating the need for external heating sources and reducing overall power dissipation.
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
The solution ensures safer and more reliable operation by evenly heating the distributor, reducing the risk of spool blocking and power dissipation, while maintaining functional advantages even with additional distributors, such as a rear distributor in agricultural applications.
Implementation Method 1
A bi-directional, two-position pilot-operated slide valve with spring and pressure-actuated active areas
Implementation Method 2
The driving of said valve having differential areas is carried out by different pressure 'signals' of connection channels inside the distributor
Implementation Method 3
the drive oil, which is the same one used for the hydraulic application of the front loader, heats until reaching temperatures above 100° C
Data Source
AI summary
A distributor (3) of the closed-center, load sensing type, connected to a variable displacement pump (1) comprises a valve device (10, 110), composed of a logic element, which is pilot-operated and configured to bring a high-pressure channel (2) into communication with a low-pressure channel (4), the connection being usually opened by the combined action of an equivalent pressure generated by an elastic member (12) and a counter-pressure which is generated, under operative conditions, in the low-pressure channel (4). The connection is closed in a switching position and it is pilot-operated to a closure position by the combined action of a high-pressure signal (P) and a load sensing signal (LS).