Series Pulse Fuel Pumps for High-Flow Four-Stroke Engines
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Solution Overview
Problem
Larger four stroke/cycle engines require higher fuel flow and pressure than can be provided by single pulse type fuel pumps, making them unsuitable for these engines due to insufficient differential pressures in the crankcase.
Innovation Solution
A pair of diaphragm-actuated, pressure-operated pulse type fuel pumps are arranged in series along the primary fuel supply path to collectively deliver the necessary fuel flow and pressure, utilizing the differential pressures in the engine crankcase as a pressure pulse source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single pulse type fuel pump is used, then the device complexity and cost are reduced, but the fuel flow rate and pressure are insufficient for larger four stroke/cycle engines
Solution Approach 1:
The single fuel pump is segmented into two separate pulse type fuel pumps operating in parallel. Each pump handles a portion of the total fuel flow requirement, allowing the system to achieve higher overall fuel flow rates and pressures while maintaining the simplicity and cost-effectiveness of individual pulse type pumps. The pumps are independently actuated by crankcase pressure pulses.
Solution Approach 2:
Two pulse type fuel pumps are merged into a single fuel supply system, with their outputs combined to deliver the required fuel flow and pressure to the engine. The pumps work simultaneously, each responding to crankcase pressure differentials, to collectively meet the demands of larger four stroke/cycle engines that a single pump cannot satisfy alone.
2Ease of manufacture
If a single pulse type fuel pump is used, then the initial cost is reduced, but the fuel pressure is insufficient for larger four stroke/cycle engines
Solution Approach 1:
The fuel pumping function is segmented across two independent pulse type pumps rather than requiring one high-pressure pump. Each pump generates pressure independently in response to crankcase differential pressures, and their combined output achieves the necessary fuel pressure for larger engines while keeping individual pump designs simple and cost-effective.
Solution Approach 2:
The dual pulse type fuel pumps are self-actuating, using the engine's own crankcase pressure differentials during the four-stroke cycle to drive the pumping action. This eliminates the need for external mechanical drive mechanisms or expensive camshaft-operated pumps, reducing initial cost while achieving sufficient fuel pressure through the combined action of both pumps.
3Device complexity
If a single pulse type fuel pump is used, then the mechanical simplicity is maintained, but the fuel flow and pressure requirements of larger engines are not met
Solution Approach 1:
The fuel delivery task is segmented between two mechanically simple pulse type pumps rather than one complex high-capacity pump. Each pump maintains the mechanical simplicity of diaphragm-actuated design with no external mechanical connections, while their combined fuel volume output satisfies the requirements of larger four stroke/cycle engines.
Solution Approach 2:
Two mechanically simple pulse type fuel pumps are merged in parallel within the fuel supply system. Both pumps operate independently using the same crankcase pressure pulses, and their fuel outputs are combined to deliver the total volume and pressure required by larger engines, preserving mechanical simplicity while increasing 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 configuration provides greater fuel flow rates and pressures, enabling the use of pulse type fuel pumps in larger horsepower four stroke/cycle engines, exceeding 25 horsepower, by synchronizing the operation of the dual pumps with the engine's pressure pulses.
Implementation Method 1
the pulse type fuel pumps may be arranged in series along the primary fuel supply path... To compensate for the lower crankcase pressures of larger four stroke/cycle engines... utilizing the differential pressures in the engine crankcase as a pressure pulse source
Implementation Method 2
the series flow arrangement provides greater fuel flow rates and pressures than what a single pulse type pump alone could deliver
Data Source
AI summary
An engine apparatus includes a fuel supply system which may comprise a fuel reservoir, primary fuel supply path extending from a fuel inlet in fluid cooperation with the fuel reservoir to a fuel outlet, pressure pulse source, and first and second pressure-operated fuel pumps located along the primary fuel supply path; each of fuel pumps operably coupled to the pressure pulse source. The fuel pumps may be pulse type pumps arranged in series from a flow standpoint along the primary fuel supply path such that fuel discharged by the first fuel pump is supplied to the second fuel pump. The fuel pumps may be mounted and to the engine or appurtenance thereof in a stacked or side-by-side relationship. The pressure pulse source may be the engine crankcase in some designs. The flow and pressures delivered by the series flow fuel pumps are suitable for use with four stroke/cycle engines.