Welded Plastic Spool Valve Assembly for Precise Pump Volume Control

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Solution Overview

Problem

Existing spool proportional valves for adjusting delivery volume flow in positive displacement pumps, such as those in motor vehicle oil systems, face issues with mechanical deformations during assembly, which affect fitting accuracy and operational tolerances, leading to suboptimal performance.

Innovation Solution

The spool proportional valve design features a plastic spring retainer and valve housing with a material-locking welded connection, avoiding mechanical deformations and ensuring precise assembly by using ultrasonic or laser welding, allowing for optimized spring preload adjustment and tolerance compensation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the spring retainer is pressed into the valve housing or fixed by caulking, then the assembly is completed, but mechanical deformations occur and fitting accuracy deteriorates

Engineering Contradiction:

Improveassembly processVSAvoidfitting accuracy

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent replaces the mechanical pressing or caulking system with an ultrasonic welding system. The spring retainer and valve housing are both made of plastic and are joined through ultrasonic welding, which eliminates the mechanical deformations and fitting accuracy issues caused by pressing or caulking operations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the material parameter of the spring retainer and valve housing to plastic (from metal), which enables a different joining method (ultrasonic welding) that avoids mechanical deformations. This material parameter change fundamentally resolves the contradiction between ease of manufacture and manufacturing precision.

Inventive Principle:

Principle #35Parameter changes

2Strength

If high assembly forces are applied to fix the spring retainer, then the connection is secure, but the valve housing and valve slide are deformed

Engineering Contradiction:

Improveconnection strengthVSAvoidfitting accuracy

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The patent replaces high-force mechanical connection methods with ultrasonic welding. The ultrasonic welding process creates a strong material-locking connection between the plastic spring retainer and valve housing without requiring high assembly forces that would deform the valve housing or valve slide.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses plastic material for both the spring retainer and valve housing, enabling a composite plastic construction that can be joined through ultrasonic welding. This material choice allows for strong connections without the deformations associated with traditional metal joining methods.

Inventive Principle:

Principle #40Composite materials

3Strength

If the spring retainer is made of metal and fixed by pressing, then the connection is strong, but mechanical deformations and negative effects on functionality occur

Engineering Contradiction:

Improveconnection strengthVSAvoidfunctionality

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent changes the material parameter from metal to plastic for the spring retainer and valve housing. This material parameter change enables ultrasonic welding as the joining method, which provides both strong connection strength and maintains functionality by avoiding mechanical deformations and negative effects.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical pressing system with an ultrasonic welding system. This substitution eliminates the mechanical deformations and negative functional effects while maintaining strong connection strength through the material-locking welded connection.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 design minimizes assembly force requirements, maintains fitting accuracy, and ensures consistent valve behavior, effectively compensating for manufacturing and dimensional tolerances, thereby improving the adjustment of delivery volume flow.

Implementation Method 1

The spring retainer and the valve housing are made of plastic and are formed with a material-locking welded connection to fix the spring retainer firmly to the valve housing, in particular by ultrasonic welding or by laser welding

Methodology Applied

Scientific EffectUltrasonic welding: Ultrasonic Vibration

Implementation Method 2

Methodology Applied

Scientific EffectLaser welding: Laser Beam Welding

Data Source

PatentEP3615853B1Proportional spool valve for adjusting the displaced volume of a displacement pump, assembly method and system

Publication Date: 2021.03.24 ETO MAGNETIC GMBH

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Figure 2a~2b
Figure 3a~4b

AI summary

The invention relates to a proportional spool valve (1) for adjusting a displaced volume of a displacement pump, in particular of an oil pump in a motor vehicle, comprising a valve housing (2) and a valve spool (3) which is slidably mounted along an adjustment axis (V) in the valve housing (2), which valve spool can slide against the spring force of a valve spring (6) supported on a spring holder (7) which is axially fixed relative to the valve housing (2) by energizing an electrical coil arrangement (10), wherein both the preferably single-piece spring holder (7) and the valve housing (2) are made from plastic and the spring holder (7) is welded to the valve housing (2) to form an integral welded connection (9).