Hydraulic Reversing Valve Mechanical Locking Piston

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Solution Overview

Problem

Existing hydraulic changeover valves for agricultural machines require complex constructions and hydraulic actuation to switch between consumers, lacking a simple mechanical solution for automatic switching when a consumer line is connected or disconnected.

Innovation Solution

A hydraulic changeover valve with a longitudinally displaceable locking piston featuring a one-piece locking head and compression spring, which automatically switches positions based on mechanical connection or disconnection of a consumer line, ensuring secure fit and efficient fluid flow management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Extent of automation

If hydraulic actuation is used to switch between consumers, then switching can be achieved, but the device complexity increases and the construction becomes complicated

Engineering Contradiction:
Improveautomatic switchingVSAvoidvalve construction
Core Design Contradiction:
Extent of automationVSDevice complexity

Solution Approach 1:

The locking piston automatically switches between consumers based on mechanical connection or disconnection of the consumer line, without requiring external hydraulic actuation. The system serves itself by using the connection action to directly actuate the locking head, which then controls the valve ports to switch the hydraulic flow path.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces complex hydraulic actuation mechanisms with a simpler mechanical direct-connection system. The locking head is mechanically connected to the consumer line such that connection or disconnection directly moves the locking piston, eliminating the need for separate hydraulic actuators and control circuits.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If a locking piston with compression spring is used, then secure fit is achieved, but the device complexity increases

Engineering Contradiction:
Improvevalve seat engagementVSAvoidlocking piston construction
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The locking head is designed as a one-piece integrated component with the locking piston, combining the sealing surface and the actuating element into a single structure. This integration ensures reliable valve seat engagement while reducing the number of separate parts and assembly steps.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The locking head features a conical profile that matches a corresponding conical valve seat, creating a tapered sealing surface. This curved geometry provides reliable sealing through surface contact while accommodating thermal expansion and manufacturing tolerances, ensuring consistent engagement.

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Ease of operation

If automatic switching is implemented, then operational simplicity is enhanced, but the manufacturing complexity increases

Engineering Contradiction:
Improveswitching operationVSAvoidvalve construction
Core Design Contradiction:
Ease of operationVSEase of manufacture

Solution Approach 1:

The locking piston serves multiple functions: it acts as a seal against the valve seat, a mechanical actuator responsive to consumer line connection, and a flow control element that directs hydraulic fluid to different consumers. This multi-functionality reduces the need for separate components while maintaining operational simplicity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 enables automatic and secure switching between hydraulic fluid supply to either a front linkage or an attachment, enhancing operational simplicity and reliability by using a mechanically actuated locking piston with a conical profile for secure valve seat engagement.

Implementation Method 1

The locking head, which is designed in one piece with the locking piston, is pressed by the force of the compression spring into its closed position

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

If the locking head has a conical profile, it ensures a secure fit on the valve seat of the first outlet in the closed position

Methodology Applied
Scientific EffectMechanical Force: Mechanical Force

Implementation Method 3

a hydraulic changeover valve with a locking piston mounted in a housing so that it can be displaced longitudinally

Methodology Applied
Scientific EffectHydraulic Pressure: Pressure Increase

Data Source

PatentEP3252358B1Hydraulic reversing valve
Publication Date: 2019.02.06 STEMPLINGER MASCHINENBAU GMBH
  • EP3252358B1 patent drawingFigure 1~2

AI summary

The hydraulic changeover valve (10) has a locking piston (24) which is longitudinally displaceable within a housing (12) that has an axial inlet port (A) and an axially opposite first outlet (E1) as well as a radially branching second outlet (E2) for a pressure medium. The locking piston (24) is displaceable against the force of a compression spring (32) from a position closing the first outlet (E1), in which the second outlet (E2) is open by the locking piston (24), to a position closing the second outlet (E2), in which the first outlet (E1) is open.According to the invention, the locking piston (24) has a locking head (28) which is pressed by the force of the compression spring (32) into the position closing the first outlet (E1), in which it rests on a valve seat (30) of the first outlet (E1) and protrudes axially from it, wherein, when a consumer line is connected, the locking head (28) mechanically releases the opening position of the first outlet (E1) against the force of the compression spring (32), in which the locking piston (24) closes the second outlet (E2).