Capacitor Discharge Press-Fit Welding High-Pressure Fuel Pump
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Solution Overview
Problem
The existing methods for producing high-pressure fuel pumps, particularly the laser welding process, face challenges such as welding splashes and longer cycle times, which complicate the manufacturing process and can introduce dirt into the pump, making it less reliable and less compact.
Innovation Solution
The use of a capacitor discharge press-fit welding (CDPF) process, which creates a firm burr at the connecting point without introducing dirt and offers a shorter cycle time, allowing for a more compact design by using a single tool for the collet chuck and electrode, and enabling a relative movement detection for quality assurance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If laser welding process is used to connect pump housing and cover element, then integrally bonded connection is achieved, but welding splashes are generated inside the pump causing contamination and requiring additional protective measures
Solution Approach 1:
The patent replaces the laser welding process (thermal/energy-based system) with a press-fit mechanical connection system. The cover element is pressed onto the pump housing with controlled force to create an interference fit, eliminating the need for welding and thus preventing welding splash contamination while maintaining connection strength.
Solution Approach 2:
The patent extracts and eliminates the welding process entirely from the manufacturing sequence. By using a press-fit connection, the harmful welding splashes are prevented at the source, and additional protective measures against welding contamination become unnecessary.
2Strength
If laser welding process is used to connect pump housing and cover element, then connection is achieved, but cycle time is extended due to additional protective measures required
Solution Approach 1:
The press-fit mechanical connection eliminates the need for laser welding setup, execution, and subsequent protective measures. The single pressing operation completes both the connection and contamination prevention, significantly reducing the production cycle time while maintaining connection integrity.
Solution Approach 2:
The press-fit connection is self-contained and self-protecting. The mechanical interference fit inherently prevents contamination without requiring additional protective components or processes, making the manufacturing process more efficient and shorter in duration.
3Length of stationary object
If cover element inside diameter is increased relative to pump housing outside diameter, then pump height is reduced through overpressing, but manufacturing precision requirements increase
Solution Approach 1:
The patent changes the dimensional parameters by providing the cover element with a larger inside diameter than the pump housing outside diameter. This parameter change enables the overpressing operation that reduces overall pump height while the controlled interference fit manages the precision requirements through material elasticity and controlled deformation.
Solution Approach 2:
The press-fit connection introduces dynamic elements to the otherwise rigid assembly. The cover element can elastically deform during pressing and then maintain a stable connection, allowing for height reduction while accommodating normal manufacturing tolerances through the dynamic press-fit mechanism rather than requiring static precision.
Data Source
AI summary
A method for producing a high-pressure fuel pump includes bringing a pump housing into contact with a lower electrode, gripping a pot-shaped cover element using a collet chuck, contacting the cover element with an electrode, bringing the open face of the cover element into contact with the face of the pump housing opposite the lower electrode, centering the cover element on the face of the pump housing opposite the lower electrode, pressing the cover element onto the pump housing in the direction of the lower electrode, and introducing an electrical current from the electrode via the cover element and the pump housing into the lower electrode, such that fusing occurs at the point of contact between the cover element and the pump housing, and such that subsequently the cover element is bonded to the pump housing. The pump housing and the cover element are connected by a peripheral weld seam.