Fuel Supply Line Venting via Suction Throttle Control
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Solution Overview
Problem
The existing methods for venting a fuel supply line in internal combustion engines with direct injection systems often result in an impermissible response of the quantity-limiting valve, leading to reduced performance and rough engine operation due to unintended fuel flow limitations during the initial start-up or after maintenance, as the air compression in the fuel line causes excessive fuel flow through the valve.
Innovation Solution
The method involves venting the fuel supply line downstream of the high-pressure pump with a suction throttle passage cross-section set to a limit that is less than or equal to a predetermined value, reducing the delivery rate to prevent the quantity-limiting valve from responding inadmissibly, and using the engine control unit to regulate the suction throttle during start-up and normal operation to ensure proper fuel flow and pressure management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fuel supply line is vented during start-up or after maintenance, then air in the fuel line is compressed and a large volume must be displaced, but this causes a large quantity of fuel to flow through the quantity-limiting valve which responds unintentionally, leading to reduced performance and rough engine operation
Solution Approach 1:
The suction throttle is set to a limit passage cross-section before venting operation begins, preemptively limiting the fuel delivery rate to prevent excessive fuel flow through the quantity-limiting valve during air compression. This preliminary configuration prevents the harmful effect before it occurs.
Solution Approach 2:
The passage cross-section parameter of the suction throttle is changed to a specific limit value during venting operation, transforming the fuel delivery rate from excessive to controlled levels. This parameter change ensures the quantity-limiting valve does not respond impermissibly while still allowing venting to occur.
2Speed
If the suction throttle passage cross-section is maximized to quickly reach predetermined pressure in the high-pressure accumulator, then pressure build-up speed is improved, but this causes excessive fuel flow that triggers impermissible response of the quantity-limiting valve
Solution Approach 1:
The passage cross-section of the suction throttle is changed to a predetermined limit value during venting operation, optimizing the balance between pressure build-up speed and fuel flow control. This parameter adjustment prevents the quantity-limiting valve from responding impermissibly while maintaining acceptable pressure build-up rate.
Solution Approach 2:
The suction throttle passage cross-section is dynamically adjusted based on operating conditions - set to the limit value during venting operation and can be increased to maximum during normal operation. This dynamic adjustment allows the system to adapt to different operational requirements.
Data Source
Figure 1
AI summary
The invention relates to a method for venting a fuel supply line (11) of a direct-injection internal combustion engine, wherein the fuel supply line (11) has an injector (3), a high-pressure storage means (15) upstream of the injector (3), a quantity-limiting valve (17) between the high-pressure storage means (15) and the injector (3) for limiting a quantity of fuel flowing from the high-pressure storage means (15) to the injector (3), and a high-pressure pump (19) upstream of the high-pressure storage means (15) for delivering fuel to the high-pressure storage means (15), wherein a pressure in the high-pressure storage means (15) is regulated by means of an intake throttle (21) which is arranged upstream of the high-pressure pump (19). In this case, provision is made for the fuel supply line (11) to be vented downstream of the high-pressure pump (19), wherein a passage cross section, which is smaller than or equal to a predetermined limit passage cross section, for the fuel is set in the intake throttle (21) during a venting operation.