Fuel Injector Enclosure Member Spring Placement
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Solution Overview
Problem
Conventional fuel injectors experience significant load on the supply pump and require large drive units due to continuous high-pressure fuel expenditure, leading to unstable movable plates and shaking of the needle during injection, which affects fuel injection control.
Innovation Solution
The injector design includes an enclosure member with a spring outside the back pressure chamber, which biases the enclosure member to control the outflow passage, reducing high-pressure fuel consumption and stabilizing the needle by maintaining communication between the outflow and back pressure chambers, while the spring's placement minimizes the back pressure chamber's capacity and reduces shaking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the outflow passage is opened in conventional injectors, then fuel can flow out from the back pressure chamber, but high pressure fuel is continuously expended causing significant load on the supply pump
Solution Approach 1:
The movable plate is extracted from the back pressure chamber and positioned at the outflow passage. When the outflow passage is opened, the movable plate moves due to pressure difference and closes the inflow passage opening, extracting the function of blocking high pressure fuel from the inflow passage itself rather than relying on continuous expenditure.
Solution Approach 2:
The movable plate acts as an intermediary between the outflow passage and the inflow passage. It responds to pressure differences caused by outflow passage opening/closing and automatically controls the inflow passage opening, mediating the connection between these two passages to prevent continuous high pressure fuel expenditure.
2Ease of operation
If the outflow passage is opened in conventional injectors, then fuel flow is enabled, but a large amount of force is necessary to close the outflow passage requiring large drive unit size
Solution Approach 1:
The movable plate performs self-service by automatically closing the inflow passage opening in response to pressure differences when the outflow passage is opened. This eliminates the need for a large drive unit to directly control the inflow passage, as the system uses its own pressure dynamics to achieve the closing action.
Solution Approach 2:
The mechanical force requirement is substituted by utilizing pressure difference dynamics. Instead of requiring a large drive unit to mechanically close the inflow passage against high pressure, the system uses the pressure difference generated by outflow passage operation to move the movable plate and close the inflow passage automatically.
3Loss of energy
If a movable plate is disposed within the back pressure chamber in a floating state, then high pressure fuel expenditure is reduced, but the orientation of the movable plate becomes unstable during operation
Solution Approach 1:
The spring provides a counterbalancing force (anti-weight equivalent in pressure terms) to the movable plate. This spring force stabilizes the movable plate's orientation by counteracting the destabilizing effects of fuel flow and gravity, allowing the movable plate to maintain stable positioning while still responding to pressure differences for operation.
4Stability of the object's composition
If a spring is disposed in the back pressure chamber to bias the movable plate, then stable operation is achieved, but the capacity of the back pressure chamber must be increased causing needle shaking
Solution Approach 1:
The spring is relocated from the back pressure chamber to another dimension/space outside the back pressure chamber. This dimensional relocation allows the spring to bias the movable plate for stable operation without occupying space within the back pressure chamber, thereby maintaining the original chamber capacity and avoiding needle shaking caused by increased capacity.
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 design effectively suppresses high-pressure fuel consumption, stabilizes the needle, and reduces shaking during injection, enhancing fuel injection control by using the enclosure member to manage back pressure and bias the needle for precise operation.
Implementation Method 1
a spring (31) disposed outside of the back pressure chamber (6), the spring (31) biasing the enclosure member (30)
Implementation Method 2
when the outflow passage (7) is opened, a fuel flow from the back pressure chamber (6) toward the outflow passage (7) is generated. As a result, the enclosure member (30) is strongly biased toward the rear side by a pressure difference in the fuel flow
Data Source
AI summary
An enclosure member includes a throughhole that penetrates a cover portion. The cover portion includes a blocking portion that receives an abutment by a wall portion to close an opening of an outflow passage with respect to spaces outside of the enclosure member. The blocking portion is provided so as to surround an opening of the throughhole, and the throughhole is in communication with the outflow passage even when the blocking portion is abutting the wall portion. Further, a spring is outside of a back pressure chamber to bias the enclosure member. The enclosure member itself blocks outside spaces from the back pressure chamber, so the expenditure of high pressure fuel may be controlled, and an injection hole may be opened and closed by a needle.