Two-Stroke Engine Crankcase Fuel Injection for Large-End Cooling
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Solution Overview
Problem
Existing two-stroke engines face challenges in effectively lubricating and cooling the large end of the connecting rod without compromising the design due to pressure and heat resistance considerations, and inefficient fuel injection timing leading to increased fuel consumption and reduced responsiveness.
Innovation Solution
A fuel injector is attached to the crankcase, injecting mixed fuel in a tangential direction to the large end of the connecting rod, lubricating and cooling it with minimal fuel, and synchronized with scavenging timing to enhance fuel efficiency and responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If fuel is injected into the combustion chamber or bore portion, then fuel can be delivered to the combustion chamber, but pressure resistance and heat resistance requirements increase the complexity of the fuel injector peripheral configuration
Solution Approach 1:
The patent extracts the fuel injection location from the combustion chamber and bore portion, placing the fuel injector in the crankcase instead. This removes the fuel injector from the high-pressure and high-temperature environment, eliminating the need for complex pressure and heat resistant peripheral configurations while still enabling effective fuel delivery to the combustion chamber through the scavenging passage.
2Quantity of substance
If conventional fuel injection methods are used, then fuel can be supplied to the combustion chamber, but lubrication and cooling of the large end of the connecting rod are insufficient
Solution Approach 1:
The patent applies local quality by directing the fuel injector specifically at the large end of the connecting rod, creating a localized fuel spray zone. This concentrated fuel delivery provides enhanced lubrication and cooling exactly where needed (at the large end) rather than relying on general fuel supply to the combustion chamber, thereby improving reliability of the lubrication and cooling function.
3Quantity of substance
If fuel injection is not synchronized with scavenging timing, then fuel can be injected, but fuel consumption increases and transient responsiveness decreases
Solution Approach 1:
The patent implements preliminary action by timing the fuel injection to occur just before or at the moment of scavenging. This synchronization ensures that fuel is delivered to the large end precisely when the scavenging passage is open and ready to receive the fuel-air mixture, preventing fuel waste and optimizing transient responsiveness by matching fuel injection with the natural scavenging cycle timing.
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 solution provides effective lubrication and cooling of the connecting rod's large end, reduces unnecessary fuel consumption, and improves transient responsiveness and startability by optimizing fuel injection timing and location.
Implementation Method 1
a fuel injector attached to the crankcase and configured to spray the mixed fuel to the large end in a tangential direction of a circumferential trajectory of the large end
Implementation Method 2
The large end is lubricated and cooled by the oil contained in the mixed fuel
Data Source
AI summary
A two-stroke engine includes a cylinder having an intake port, a piston configured to open and close the intake port by reciprocating in the cylinder, a crankcase connected to the cylinder and including a crank chamber, a crank assembly located in the crank chamber, a connecting rod having a first end connected to the piston and a second end connected to the crank assembly, and a fuel injector attached to the crankcase and configured to inject mixed fuel to the second end.