Flowmeter for measuring extremely low fuel mass flows

#The present invention relates to flowmeters for measuring the mass per unit time of flow of a liquid. More particularly, the present invention is a flowmeter for measuring a quantized mass of fuel flow. Still more particularly, the present invention is a flowmeter of the aforesaid type capable of measuring extremely small fuel mass flow quanta.

#The ever increasing sophistication of control of the various processes of internal combustion engines has provided increased mileage, decreased emissions and better overall performance. These advances include the widespread use of electronic controls and fuel injection. Fuel injectors, controlled electronically, provide precise, timed fuel injections directly into the combustion chamber at the most opportune portion of the engine cycle. One of the remaining issues of engine control relates to knowing the real-time quantized fuel flow mass delivered to a combustion chamber by its respective fuel injector.

#Fuel flows, on a cycle resolved or on a per injection basis, have been difficult, if not impossible to quantify using conventional mass flowmeters. Therefore, a new style of mass flow meter is required to quantify small flows (mass quanta) accurately to within 0.1 mg per injection. The need for this type of higher accuracy device is to make better mass specific emission measurements. Fast low flow exhaust devices exist for cycle resolved emissions but no information is available for cycle resolved input of the reactants. Further, most other flowmeters do not operate at the high pressures required for direct injection internal combustion engines.

#FIG. 1 is a side view of a the flowmeter according to the present invention, shown in operation with respect to a fuel injector.

#FIG. 2 is a partly sectional side view of the flowmeter according to the present invention, shown at the end of a first quantum of fuel mass flow along a first flow path.

#FIG. 3 is a sectional view, seen along line 3A-3A of FIG. 2.

#Referring now to the Drawing, FIG. 1 depicts an environment of operation of the flowmeter 10 according to the present invention. The flowmeter 10 is located between a source of pressurized fuel 12 and a fuel injector 14. An electronic control module 16 is connected to an external circuit 18, wherein electronic components of the flowmeter (discussed hereinbelow) are operably interfaced. Pressurized fuel F (as for example between 1,000 and 5,000 psi) is delivered to the fuel injector 14 by the pressurized fuel source 12, wherein the fuel passes through the flowmeter 10. The flow of fuel is quantized, in that an injection is timed pursuant to programming of an engine control module which regulates the injection function of the fuel injector.

#The primary intent of the present invention is it to provide direct fuel mass flow measurements on an actual pressurized fuel line proximal the fuel injector, wherein data is realized on a cycle-by-cycle basis, and wherein it is preferred for the flowmeter to have sufficient hydraulic damping and fast enough signal response time for providing real-time data output on an intracycle basis. The sensor output of the flowmeter is converted electronically by an algorithm to mass flow data. The secondary intent of the present invention is to keep the size of the flowmeter small enough to enable the installation under the hood of test vehicles.

#Referring now additionally to FIGS. 2 through 5B, the structure and function of the present invention will be detailed.