Overflow Valve Radial Bore Leakage Management
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Solution Overview
Problem
Existing fuel injection systems for internal combustion engines are complex due to the need for separate throttles and lack of efficient leakage quantity management, leading to increased manufacturing effort and costs.
Innovation Solution
A simplified fuel injection system design where the leakage quantity of the metering unit flows via an essentially radially running bore in the valve piston of the overflow valve, eliminating the need for a separate throttle and allowing for a Venturi nozzle-style cross-sectional constriction, which ensures efficient outflow during zero delivery, and optional constant lubrication and cooling through a through-bore or blind hole central bore.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate throttle is provided in the outflow for the leakage quantity of the metering unit, then the leakage quantity can be controlled, but the structure of the fuel injection system becomes complex
Solution Approach 1:
The patent combines the throttle function with the overflow valve by integrating a throttling element directly into the overflow valve structure. The overflow valve now serves dual purposes: regulating system pressure through axial displacement of the valve piston and controlling leakage quantity through the integrated throttle. This merging eliminates the need for a separate throttle component, reducing structural complexity while maintaining leakage control capability
Solution Approach 2:
The overflow valve is designed to perform multiple functions simultaneously. Besides its traditional pressure regulation function through the axially displaceable valve piston that opens or closes outflow openings, it now also controls the leakage quantity of the metering unit through the integrated throttle in the outflow channel. This multi-functionality reduces the total number of components needed in the system
2Reliability
If additional components are added to manage leakage quantity, then leakage control is improved, but manufacturing effort and costs increase
Solution Approach 1:
By merging the throttle function into the overflow valve structure, the patent reduces the total number of discrete components that need to be manufactured and assembled. The integrated design allows for fewer separate manufacturing processes and assembly steps, thereby reducing manufacturing effort and associated costs while maintaining effective leakage control
3Device complexity
If no drain is provided for leakage quantity, then the system structure is simpler, but the leakage quantity cannot be effectively managed
Solution Approach 1:
The patent resolves this contradiction by integrating the drainage function for leakage quantity directly into the overflow valve structure. The outflow channel with the integrated throttle provides an effective drainage path for leakage quantity while maintaining a relatively simple overall system structure. This eliminates the need for separate drainage components while ensuring proper leakage management
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 design simplifies the system structure, reduces manufacturing costs, and ensures continuous outflow of leakage quantities without the need for additional throttles, while allowing for constant lubrication and cooling, enhancing operational efficiency.
Implementation Method 1
The narrowing of the cross section of the flow channel can be designed in the manner of a Venturi nozzle, which ensures that the leakage quantity of the metering unit flows away when there is no delivery.
Data Source
Figure 1
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AI summary
The invention relates to an overflow valve for a fuel injection system, in particular a common rail injection system, wherein the fuel injection system comprises a pre-supply pump (1) and a high-pressure pump (3), to which fuel from a fuel tank (2) is delivered by means of the pre-supply pump. The fuel injection system further comprises a metering unit (4) for regulating the amount of fuel to be delivered to at least one pump element (6) of the high-pressure pump (3) via an inlet (5). The overflow valve (7) is arranged between the pre-supply pump (1) and the metering unit (4) and comprises an axially displaceable valve piston (8), the axial displacement of which allows at least one discharge opening (9) to be opened or closed. According to the invention, an axially extending flow channel (10) having a cross-section constriction (11) is formed inside the valve piston (8), wherein in the region of the cross-section constriction (11) a substantially radial borehole (12) leads into the flow channel (10), via which borehole the flow channel (10) can be hydraulically connected to the inlet (5) downstream of the metering unit (4).