Fuel Delivery Pump Shaft Electrical Insulation
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Solution Overview
Problem
Fuel feed pumps in motor vehicles face challenges in preventing electrostatic discharges and avoiding short circuits, which can lead to reduced service life due to insufficient grounding and potential deposits within the electric motor.
Innovation Solution
The implementation of electrical insulation elements between the axial and radial bearings and the pump stage, using cup-shaped and pot-shaped insulating elements, along with non-conductive materials or coatings, to electrically isolate the shaft from grounded elements, allowing safe grounding of the pump housing and motor housing while preventing short circuits and deposits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pump stage and motor housing are grounded to protect against electrostatic discharge, then protection against ESD is improved, but the shaft becomes short-circuited to ground potential leading to deposits and reduced service life
Solution Approach 1:
The electrical grounding system is segmented into two separate paths: the pump stage and motor housing are grounded through the fuel pump housing to the vehicle ground, while the shaft is electrically isolated from ground potential through insulating elements (plastic or ceramic bearings) at the bearing supports. This segmentation allows simultaneous ESD protection and prevention of shaft short-circuiting.
Solution Approach 2:
Electrically insulating intermediate elements (insulating bearing supports made of plastic or ceramic materials) are introduced between the shaft and the grounded pump stage. These intermediaries prevent direct electrical contact between the shaft and ground potential while allowing mechanical support and rotation, thus avoiding shaft short-circuiting and deposit formation.
2Reliability
If additional resistors are used to achieve sufficient grounding or decoupling, then ESD protection is improved, but device complexity increases
Solution Approach 1:
The fuel pump housing itself serves as the grounding path to the vehicle ground, eliminating the need for additional grounding resistors or complex electrical decoupling devices. The housing naturally provides the grounding function while the insulating bearing supports provide the necessary electrical isolation of the shaft.
3Reliability
If a plastic pump stage is used to insulate the shaft, then electrical insulation is improved, but stability decreases leading to shorter service life
Solution Approach 1:
Instead of making the entire pump stage from plastic, only the localized contact points between the shaft and the pump stage (the bearing supports) are made from electrically insulating materials. The main pump stage body can remain structurally stable while having insulating elements only where electrical isolation is needed.
Solution Approach 2:
The fuel pump system uses a composite construction combining conductive materials (metallic pump stage and housing for ESD protection) with electrically insulating materials (plastic or ceramic bearing supports for shaft isolation). This composite approach allows simultaneous achievement of ESD protection and shaft electrical insulation without compromising structural stability.
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 solution effectively protects against electrostatic discharges and prevents unwanted deposits, enhancing the service life of the fuel feed pump by ensuring comprehensive electrical insulation and safe grounding without compromising the pump's stability.
Implementation Method 1
an electrical insulating element is arranged between the axial bearing and the pump stage
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a fuel delivery pump (4, 15) for delivering fuel, having an electric motor (18) and having a pump impeller which can be driven by way of the electric motor (18), wherein the pump impeller is connected to a rotor (17) of the electric motor (18) by means of a shaft (16) in such a way that a rotational movement of the rotor (17) is transmitted via the shaft (16) to the pump impeller, wherein the shaft is mounted in the axial direction by way of an axial bearing (12) and/or in the radial direction by way of a radial bearing (20) with respect to a pump stage (11), in which the pump impeller is arranged, wherein an electrical insulation element (13) is arranged between the axial bearing (12) and the pump stage (11) and/or an electrical insulation element is arranged between the radial bearing (20) and the pump stage (11).