Measuring and testing – Internal combustion engine or related engine system or... – Compression
Patent
1981-08-07
1983-09-20
Myracle, Jerry W.
Measuring and testing
Internal combustion engine or related engine system or...
Compression
73113, G01M 1500
Patent
active
044048475
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
This invention relates generally to circuits wherein fluid flow is required to be accurately measured, more particularly, this invention relates to circuits for testing fuel injection system components.
2. Background Art
Circuits for measuring fluid flow generally and, more particularly, circuits which circulate and measure the flow of fuel to test injection pumps, such as diesel injection pumps, have not kept pace with the stringent demands of research and development and governmental requirements wherein accurate flow measurement is imperative. Typically, flow measurement circuits not only achieve flow measurement accuracies within .+-.7% of the actual flow.
In attempting to achieve accurate flow measurements, numerous circuits have been developed which recognize the importance of and strive toward conditioning fuel so that accurate and meaningful flow measurements can be taken. Conditioned fuel is fuel at a standard, constant temperature and pressure and which is relieved of objectionable air entrained or dissolved within the fuel. Once the fuel has been conditioned, accurate and repeatable flow measurement can be made.
One type of such a flow circuit is exemplified by U.S. Pat. No. 3,973,536 issued Aug. 10, 1976 to Wim Zelders. This flow circuit has pressure and temperature controls and overpressurizes the circuit to prevent air entrained in the fuel from becoming disentrained. The drawbacks of this type of circuit are that:
(1) Dissolved air tends to dissociate to form bubbles of entrained air as the pressure drops at flow discontinuities such as elbows, valve ports, and flow control orifices. When dissolved air has dissociated, the fuel becomes a mix of compressible and incompressible parts. This destabilizes the volumetric efficiency of pumps and flow meters with loss of repeatability and accuracy.
(2) No dampening is provided to dampen pulses in the fuel generated by the operation of the injection pump thereby subjecting the flow meter to these pulsations which possibly could damage the flow meter and contributes to the inaccuracy and lack of repeatability of the flow meter.
(3) No apparatus is provided whereby a newly inserted test injection pump can be purged of trapped air prior to testing thereby preventing entrainment of more air.
And (4), while the temperature control provides equalization of fuel temperature, it does not provide a mechanism to hold fuel at a specific, standard temperature resulting in the passing of fuel of differing density through the flow meter as the temperature of the fuel fluctuates over a period of time.
Another type of flow measuring circuit is described in U.S. Pat. No. 3,750,463 issued Aug. 7, 1973 to Curtis L. Erwin, Jr. This circuit does have means to disentrain air within the fuel, however, the means are located downstream of the flow meters thereby still subjecting the flow meters to the compressible flow caused by entrained air. Further, no pressure or temperature controls nor pulsation dampening are provided which would enable the circuit to pass through the flow meter a fuel that has been conditioned and which will not subject flow meters to troublesome fuel pulsations.
The present invention is directed to overcoming one or more of the problems as set forth above.
DISCLOSURE OF THE INVENTION
In one aspect of the present invention a fuel supply flow measuring circuit is provided for testing a fuel injection apparatus. The circuit has a fuel reservoir, a pump communicating with the reservoir for supplying fuel to the injection apparatus, means for measuring the flow of fuel supplied to the injection apparatus, and means for controlling the pressure of the supply fuel to the injection apparatus. In particular the circuit has means for removing entrained air from the fuel which includes a first deaeration means interposed between the pump and the injection apparatus and a second deaeration means located downstream of the injection apparatus for removing entrained air from the fuel leaving the injection apparatus.
BRIEF DESCRI
REFERENCES:
patent: 2747555 (1956-05-01), Brunner
patent: 3577776 (1971-05-01), Brown
patent: 3750463 (1973-08-01), Erwin, Jr.
patent: 3831439 (1974-08-01), Konomi
patent: 3973536 (1976-08-01), Zelders
patent: 4134301 (1979-01-01), Erwin, Jr.
Jennings, R. Fuel Economy Measurement . . . Transducers from Proceedings of 22nd International Instrumentation Symposium, 1976, pp. 193-203.
Caterpillar Tractor Co.
Myracle Jerry W.
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