Fuel Injector Cooling via Variable Nozzle Slots
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Solution Overview
Problem
Fuel injectors in diesel engines linked in series to a low-pressure fuel supply and drain rail experience uneven operating temperatures due to heat accumulation, leading to dimensional instability and unreliable performance, with existing cooling methods either insufficient or costly.
Innovation Solution
The system manipulates the size of slots or openings in the nozzle cases and flow rates within the nozzle cases to balance cooling rates across fuel injectors, providing a lower cooling rate for upstream injectors and a higher cooling rate for downstream injectors, thereby balancing operating temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fuel injectors are linked in series to a low pressure fuel supply and drain rail, then the system structure is simplified and cost is reduced, but the downstream fuel injectors experience excessive heat accumulation leading to dimensional instability and unreliable performance
Solution Approach 1:
The patent applies local quality by providing different cooling rates to different locations along the fuel rail. Specifically, the first fuel injector receives a first cooling rate while the second fuel injector receives a second cooling rate that is greater than the first cooling rate. This localized differentiation of cooling intensity compensates for the heat accumulation gradient along the series-connected fuel rail, ensuring that each injector operates within its optimal temperature range without requiring a complete system redesign.
Solution Approach 2:
The patent utilizes parameter changes by dynamically adjusting the cooling rate parameter for each fuel injector based on its position in the series connection. The control system monitors temperature or position and modifies the cooling intensity accordingly, allowing the first injector to receive lower cooling and the second injector to receive higher cooling. This parameter adjustment resolves the thermal imbalance caused by series connection while maintaining the simplified system structure.
2Temperature
If indirect cooling methods are used such as passing cooling water through the cylinder head, then cooling is provided to the fuel injectors, but the cooling effectiveness is insufficient and additional cost is incurred
Solution Approach 1:
The patent applies self-service by utilizing the fuel itself as the cooling medium rather than introducing a separate cooling system. The fuel circulating through the series-connected fuel rail naturally absorbs heat from each injector, and this self-cooling effect is enhanced by optimizing the fuel flow distribution. This approach eliminates the need for external cooling water systems while providing adequate temperature control for all injectors.
Solution Approach 2:
The patent employs hydraulic principles by using the pressurized fuel flow to provide cooling. The fuel, under pressure from the fuel supply system, circulates through the fuel rail and absorbs heat from the injectors. By optimizing the hydraulic flow distribution to provide greater flow to downstream injectors, the system achieves effective cooling without requiring separate cooling infrastructure.
3Reliability
If larger fuel supply pumps and fuel cooling mechanisms are implemented, then fuel injector cooling is improved, but the engine cost increases significantly
Solution Approach 1:
The patent applies universality by making the fuel serve multiple functions simultaneously: it acts as both the working fluid for fuel injection and the cooling medium for temperature control. The same fuel that is being delivered to the injectors also absorbs heat from them during circulation through the fuel rail. This multi-functionality eliminates the need for separate cooling pumps and mechanisms, maintaining system simplicity while ensuring reliable temperature control.
Solution Approach 2:
The patent merges the fuel delivery function and the cooling function into a single integrated system. Instead of having separate systems for fuel supply and temperature control, the fuel circulation loop serves both purposes. The fuel rail structure is designed to facilitate heat transfer from the injectors to the passing fuel, combining what would traditionally be separate functions into one unified approach.
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 effectively balances the operating temperatures of fuel injectors along the fuel rail, enhancing their reliability and performance while avoiding the high costs associated with existing cooling solutions.
Implementation Method 1
heat is added to the fuel rail at each injector for a variety of reasons. For example, hot fuel spilled from a fuel injector to the surrounding injector bore in the cylinder head can generate substantial amounts of heat that is transferred back to the fuel rail
Data Source
AI summary
Various fuel injection systems and fuel injectors are disclosed that provide varying cooling rates for fuel injectors connected in series to fuel supply and drain rail. The local cooling rate for each injector is manipulated to balance the heat flux or heat transfer across the injectors disposed along the rail. The cooling rates may be manipulated by varying sizes of openings or slots in the nozzle case, by varying annular spaces disposed between the nozzle case and the portion of the injector body that houses the actuator and solenoid assembly, and by varying the size of annular spaces disposed between the nozzle case and the cylinder head. Strategic placement of slots in the nozzle case that direct more flow at the portion of the injector body that houses the actuator and solenoid assembly may also be employed. As a result, the operating temperatures of fuel injectors connected in series to a fuel rail can be manipulated and moderated so the downstream injectors are not prone to overheating.