Fuel Metering Unit Axial Groove Pressure Compensation
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Solution Overview
Problem
Existing fuel metering units for internal combustion engines face challenges in operating behavior and service life, with increased costs due to the need for pressure equalization bores and complex manufacturing processes.
Innovation Solution
Integration of axial grooves within the bearing bushes of the fuel metering unit to provide pressure compensation, allowing for reduced frictional resistance and simplified manufacturing, eliminating the need for additional pressure equalization bores and enabling cost-effective production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pressure equalization bores are provided in the base of valve piston or armature, then fuel pressure equalization is achieved, but device complexity and manufacturing costs increase
Solution Approach 1:
The patent combines the pressure equalization function with the bearing bushing structure by integrating axial grooves directly into the bearing bushing. This merging eliminates the need for separate pressure equalization bores in the valve piston base or armature, reducing device complexity while maintaining the pressure equalization function. The bearing bushing now serves dual purposes: guiding the armature bolt and providing pressure equalization pathways.
Solution Approach 2:
The bearing bushing is designed to perform multiple functions simultaneously: it guides the armature bolt axially and provides pressure equalization through integrated axial grooves. This multi-functionality reduces the overall number of components needed in the fuel metering unit, simplifying the device structure while ensuring reliable pressure equalization during operation.
2Ease of manufacture
If axial grooves are integrated into bearing bushes, then manufacturing costs are reduced and pressure equalization is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The axial grooves for pressure equalization are integrated directly into the bearing bushing structure during the extrusion process. This combination eliminates the need for separate pressure equalization components and reduces the number of assembly steps, lowering manufacturing costs while maintaining precise guidance of the armature bolt through the bearing bushing.
Solution Approach 2:
The axial grooves are formed during the extrusion process itself, before final assembly. This preliminary formation of pressure equalization pathways during material shaping reduces subsequent machining requirements and ensures precise geometry is achieved during the forming process, balancing manufacturing precision requirements with cost effectiveness.
3Ease of operation
If axial grooves are provided on bearing bush, then frictional resistance is reduced, but bearing surface area decreases
Solution Approach 1:
The bearing bushing is designed with axial grooves that create local variations in the bearing surface. The grooves are positioned to reduce frictional resistance in critical areas where the armature bolt moves, while maintaining sufficient bearing surface area in other regions. This local modification optimizes ease of operation without compromising overall bearing capacity.
Solution Approach 2:
The axial grooves in the bearing bushing create fluid pathways that allow fuel to enter the bearing interface and reduce friction through hydrodynamic or hydrostatic effects. This pneumatic/hydraulic approach reduces frictional resistance during operation while the groove geometry is designed to maintain adequate bearing surface area for load support.
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 enhances the operating behavior and service life of the fuel metering unit while reducing production costs by minimizing frictional resistance and maintaining a constant inner bore, ensuring precise guidance and efficient fuel flow regulation.
Implementation Method 1
pressure equalization bores are provided, for example, in a base of a valve piston and/or in the armature of the fuel metering unit. According to the invention, these pressure compensation bores are at least partially integrated into the bearing bushings that are necessary anyway for guiding the anchor bolt, in that they have an axial groove.
Implementation Method 2
The invention also relates to a fuel pump according to the preamble of the corresponding independent patent claim. Such a fuel metering unit is known from DE 10 2005 025 872 A1. This fuel metering unit is used to control the flow rate of a fuel pump on the intake side, which is part of a fuel injection device of an internal combustion engine. The fuel metering unit has a control valve actuated by an electromagnet with a valve member
Implementation Method 3
These bearing bushes are manufactured separately with high accuracy, preferably from an extruded profile, in order to achieve a firm seat of the bearing bush in a valve housing on the one hand and the best possible guidance for the armature bolt on the other. One or more axial grooves can already be provided on the bearing bush during the forming process that takes place during extrusion without additional production costs.
Data Source
Figure 1
Figure 2
AI summary
The unit has a regulating valve that is actuated by an electromagnet, where the electromagnet moves an anchor bolt by magnetic force. The anchor bolt is mounted on a bearing bush (52) in an axially adjustable manner, where an axial groove (56) is provided in the bearing bush. The axial groove is arranged at an outer side or an inner side of the bearing bush. An inner side of the bearing bush is cylindrically arranged in regions and works as a bearing surface (55) for the anchor bolt in the regions.