Fuel Injection System Pre-Supply Pump Venting
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Solution Overview
Problem
Existing fuel injection systems with complex structures and high production costs require additional effort and resources for filling and venting, which is inefficient and costly, especially due to the reduced clearance in modern high-pressure pumps that hinder air escape and lead to non-start issues.
Innovation Solution
The system allows filling and venting via the pump element's inlet and outlet valves, utilizing the pre-supply pressure from the electric fuel pump to overcome the high-pressure pump's opening pressures, ensuring complete venting and flushing out particles, thus eliminating the need for additional effort and reducing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a bypass connection with a check valve is added to enable filling and venting, then the fuel injection system can be filled and vented, but the structure becomes complex and production costs increase
Solution Approach 1:
The high-pressure pump's own inlet and outlet valves are utilized to perform the filling and venting function, eliminating the need for separate bypass connections and check valves. The pump element serves dual purposes: both fuel delivery and system venting, by allowing the pre-supply pump to pressurize fuel through the pump element's valves during startup.
Solution Approach 2:
The inlet and outlet valves of the pump element, originally designed for fuel delivery, are made to serve an additional function of system venting and filling. By designing these valves with sufficiently low opening pressures, they can be opened by the pre-supply pump to vent air from the element space and allow fuel filling without requiring dedicated venting components.
2Manufacturing precision
If the clearance between pump piston and guide bore is reduced to improve pump performance, then manufacturing precision increases, but air escape is hindered causing non-start issues
Solution Approach 1:
The air venting function is extracted from the clearance between the pump piston and guide bore, which is no longer relied upon for this purpose. Instead, a dedicated venting path is created through the inlet and outlet valves of the pump element, which are specifically designed to open at low pressures to allow air escape during startup.
3Reliability
If additional components are added for filling and venting, then the system can be filled and vented completely, but production costs increase
Solution Approach 1:
The existing inlet and outlet valves of the pump element are made to serve the additional function of enabling complete system venting and filling during startup. By designing these valves with sufficiently low opening pressures, they can be reliably opened by the pre-supply pump to vent air from all system components including the common rail and injectors, eliminating the need for additional venting components.
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 approach enables efficient filling and venting, ensuring complete system refilling, rapid pressure build-up in the high-pressure accumulator, and preventing non-start issues by using the pre-supply pressure to overcome valve opening pressures and flush out contaminants, resulting in a cost-effective and reliable fuel injection system.
Implementation Method 1
The pre-supply pressure of the pre-supply pump is at least equal to the total opening pressure of the valves of the high-pressure pump
Implementation Method 2
The high-pressure pump has at least one pump element with a first valve serving as an inlet valve and a second valve serving as an outlet valve
Implementation Method 3
A high-pressure accumulator is connected to the high-pressure pump in the form of a common accumulator line, in which a pressure control valve is accommodated
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3
AI summary
The invention relates to a fuel injection system, in particular to a common rail injection system, comprising a pre-supply pump (1) and a high-pressure pump (2), wherein the high-pressure pump (2) is used to apply a high pressure to the fuel and comprises at least one pump element having a first valve, which is used as inlet valve (3), and a second valve, which is used as an outlet valve (4). According to the invention, the pre-supply pump (1) is an electrical fuel pump, by means of which a pre-supply pressure can be achieved, which is equal to or greater than the total opening pressure of both valves (3, 4) of the pump element such that rapid filling and/or venting can be effected during the initial start in the vehicle plant or when restarting after an empty tank. The invention further relates to a method for filling and/or venting such a fuel injection system.