Liquid fuel supply system for an atomization burner nozzle

A system for supplying fuel to an atomization fuel oil burner nozzle from a fuel pump at a rate less than that rated for the nozzle for burning of less fuel while achieving good combustion. The fuel is delivered to the nozzle at a pulsing frequency which is dynamically matched to intermittent pressure pulses within the fuel pump to create resonant pressure peaks at the nozzle. The fuel pump creates a pressure pulse each time a tooth of one gear of the pump makes full penetration into the space between a pair of teeth of a coacting rotatable ring gear. Rotatable valving structure, including gear ports in the rotatable ring gear pulses fluid flow to the nozzle by alternately connecting a fluid outlet of the pump to either a pressure port within the pump at the time of a pressure pulse or to the fuel pump inlet with the pressure peak of the pulsed flow being phased together with said pressure pulse.

BACKGROUND OF THE INVENTION 
This invention relates to a liquid fuel supply system for an atomization 
burner nozzle wherein the liquid fuel is supplied at a pulsing pressure 
characterized by supplying the nozzle with fuel at a continually-varying 
positive gauge pressure for a first period of time and interrupting the 
fuel supply during a second period of time. The pulsation pressure peaks 
are phased together with the pressure peaks of the natural pulsations 
occurring within the fuel pump structure to enhance the positive values of 
the pulsation pressure peaks and pump pressure peaks during said first 
period of time and the negative values of the pressure during said second 
period of time as well as the pressure rates of rise and fall, 
respectively, so as to minimize the time when positive sub-atomization 
fuel pressures are present at the atomizing nozzle. 
Properly sized fuel oil fired heating systems for maximum efficiency are 
difficult to obtain for certain smaller-sized heating requirements, such 
as mobile homes, apartments, and small homes as well as larger dwellings 
during less severe heating seasons because of plugging problems with high 
pressure atomization nozzles. If the nozzle is sized sufficiently small 
for reduced delivery of fuel from the nozzle, it becomes subject to 
plugging by particulate material. Other methods of obtaining proper fuel 
flow rates, such as low pressure air-oil nozzles and sonic atomizers 
require other modifications to the heating system which add significant 
cost. 
One system developed for delivering less than normal fuel through a nozzle 
is disclosed in Robert W. Erikson application Ser. No. 023,428, filed Mar. 
23, 1979, now U.S. Pat. No. 4,255,093 and owned by the assignee of this 
application. In the structure of the Erikson application, the high 
pressure discharge from the pumping elements of the fuel pump is directed 
through a metering orifice open at timed intervals to provide a relatively 
low volume of flow to the burner nozzle, while avoiding the clogging 
problem. 
A more recent system is that disclosed in James Harvey Moore Meyer 
application Ser. No. 165,565, filed July 3, 1980, and owned by the 
assignee of this application. In the method and structure disclosed in the 
Meyer application, the fuel is delivered to an atomization nozzle at a 
pulsing frequency which is dynamically matched to intermittent pressure 
pulses within the fuel pump to create resonant pressure peaks at the 
nozzle above normal regulated pressure with intermittent negative values 
of pressure to result in reduced flow of fuel through the nozzle. 
It is also known in the art to supply fuel to an atomization nozzle from a 
fuel pump supplying fuel at a constant pressure and interrupting the 
delivery of fuel to the nozzle periodically to reduce the total rate of 
flow per unit of time through the nozzle by means of a rotatable member 
which blocks communication between the fuel pump and nozzle and during the 
blocked interval connects the nozzle to the pump inlet or source of fuel. 
Such a system does not provide a good workable system with high combustion 
efficiency at the nozzle. 
SUMMARY OF THE INVENTION 
This invention relates to a system for delivery of liquid fuel to an 
atomization fuel oil burner nozzle by connecting the nozzle intermittently 
to either a source of fuel under pressure or pump inlet and the connection 
to the source of pressure being operable to phase together the pressure 
peaks of the natural pulsations occurring within the pump and the pressure 
peaks of the periodic pulsations of the connection between the pump and 
nozzle. This enhances the positive values of the pressure peaks when the 
nozzle is connected to the pressure source and the negative values of the 
pressure during the time period of connection to the pump inlet. 
In carrying out the foregoing, a fuel pump has a fluid inlet and a fluid 
outlet with a pressure port and an inlet port, rotatable pump gears which 
pump fuel from the inlet port to the pressure port with a pressure pulse 
created each time a tooth of one gear makes full penetration into the 
space between a pair of teeth on the other gear, timing ports connected to 
the fluid outlet and rotatable valve means including gear ports in one of 
said rotatable gears for periodically connecting either the pressure port 
or the inlet port to the pump fluid outlet and with phasing of the 
intermittently-connected parts to have the pressure peak of the pulsed 
flow to the pump fluid outlet occurring at the time of the pressure pulse. 
Additional objects of the invention are to provide a liquid fuel supply 
system wherein: the fuel flow rate supplied to the nozzle can be varied by 
varying the time relation between the time in which the pulsed flow is 
operative and the time in which the nozzle is connected to the fuel source 
by varying the rotating speed of the pump; the feed relation between the 
pump and the combustion air supply mechanism is maintained whereby the 
ratio of fuel flow rate to airflow rate remains such that good combustion 
of fuel results at any of the preferred rotating speeds of the pump; and 
the speed of the pump can be varied either manually or by a system which 
senses the fuel flow requirement.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The liquid fuel supply system includes a fuel pump P, shown in FIGS. 1 to 
5, wherein a pump housing includes a casting 10 and a cover 11 suitably 
secured thereto and having a reservoir 12 which, through a strainer 15, 
can supply fuel, such as oil, to pump elements associated with additional 
parts of the housing including a port plate 20 and a plate 21 surrounding 
the pumping elements and which are suitably attached to the casting 10 as 
by means 24. 
The pump has a fluid inlet 25 which, through a passage 26, supplies a 
kidney-shaped inlet port 27 in the port plate 20. The pump has a pair of 
fluid outlets, with there being a fluid outlet 30 for pulsed fuel flow and 
a fluid outlet 31 for continuous fuel flow. A return port 32 connects to a 
fuel tank having a source of fuel for the fluid inlet 25. 
The pump includes a pair of pumping elements, in the form of rotatable 
gears, located within an opening of the plate member 21. There is an 
externally-toothed inner gear 33 mounted on a shaft S for rotation and a 
surrounding internally-toothed ring gear 34 which together rotate between 
the fluid inlet port 27 and an arcuate kidney-shaped pressure port 35 in 
association with a crescent member 36 deliver pressurized fluid to the 
pressure port 35 in the port plate 20. It is a characteristic of such a 
pump that there is a pressure pulse each time a tooth 37 of the inner gear 
makes full penetration into the space between a pair of teeth 38 of the 
ring gear. 
The pressure port 35 communicates with the fluid outlet 31 of the pump 
through housing passages 40 and 41, shown diagrammatically in FIG. 5, with 
the passage 41 leading to a bore 42 in which a pressure-regulating valve 
is mounted. The ends of the bore 42 are closed by a pair of threaded caps 
43 and 44. The threaded cap 43 has a passage 45 leading to the fluid 
outlet 31 and has an end forming a valve seat against which a seat member 
50 of a pressure-regulating valve member 46 is urged by a spring 47 
positioned within the interior of the valve member and abutting against a 
surface thereof and its opposite end abutting against a threaded 
adjustment member 48 carried in the end cap 44. The adjustment of the 
spring 47 determines the pressure of the fuel delivered through the fluid 
outlet 31. The valve member 46 remains closed until the pressure of the 
fuel delivered from the pressure port 35 is sufficient to overcome the 
force of the spring and then the valve member moves to the right as viewed 
in FIG. 5 to move the seat member 50 away from the valve seat and permit 
flow to the fluid outlet. The pressure is regulated by an annular land 51 
on the exterior of the valve member which coacts with a fluid passage 52 
for delivery of fuel oil back to the return port 32. The bore 42 has a 
pair of passages 55 and 56 which are capped and not used. An end of the 
passage 40 leading to the pressure-regulating valve has a bleed valve 58 
operable in a known manner for bleeding the pressure line. A line 150 
connects a pump seal chamber to the fluid passage 52 for return of leakage 
oil to the return port. 
The flow to the fluid outlet 30 is pulsed flow which is achieved by 
intermittent pulsing of fuel under pressure from the pressure port 35 to 
the outlet. The structure for accomplishing this includes an elongate 
arcuate passage 60 in the plate 21 of the pump housing which at least 
partially spans the arcuate inlet port 27 and the arcuate pressure port 35 
and lies at a greater distance from the axis of rotation of the shaft S 
and communicates with the fluid outlet 30 by means of a passage 61. 
The arcuate passage 60 communicates with the passage 61 extending to the 
fluid outlet 30 through a passage 61a in the casting 10, indicated 
diagrammatically in FIG. 5. 
A discharge timing port 65, formed in the plate 21, extends inwardly from 
the arcuate passage 60 to connect the arcuate passage with the outer 
periphery of the ring gear 34. As the pump gears are rotated, the pressure 
port 35 intermittently communicates with the arcuate passage 60 through 
the discharge timing port 65, with this intermittent communication being 
accomplished by rotatable valve means in the form of gear ports formed in 
the ring gear 34 and extending radially outward from a radial location of 
overlap with the pressure port 35 and from the roots between certain pairs 
of teeth on the ring gear to the outer periphery of the ring gear. In the 
pump construction shown, there is a gear port 67 extending radially 
outward from every other root of the ring gear which results in there 
being a relation of one gear port for every other pressure pulse caused by 
the full penetration of a tooth 37 on the inner gear 33. 
Referring particularly to FIG. 3, the relation of pump structure shortly 
prior to a pressure pulse within the pump gears is shown wherein a gear 
port 67 is communicating with the discharge timing port 65 to connect the 
pressure port 35 to the arcuate passage 60. It will be noted that there is 
a gear port 67 that has moved beyond the discharge timing port 65 and 
which communicates with the space between teeth which will shortly, beyond 
the point shown, be in full penetration. The latter gear port is inactive. 
The gear port 67 shown communicating with the discharge timing port 65 has 
a lesser width than the discharge timing port and these last two ports are 
related whereby the trailing end of the gear port 67 will move past the 
trailing end of the discharge timing port 65 immediately after the 
pressure pulse created by the full penetration of the gear tooth 37a into 
the space between a pair of gear teeth on the ring gear 34. The pressure 
peaks of the main fuel pump pulsation created by the communication of a 
gear port 67 with the discharge timing port 65 occurs at the last point in 
time during which the gear port 67 communicates with the discharge timing 
port 65. The main fuel pump pulsation is phased together with the pressure 
peak of the natural pulsation occurring within the pump gears to enhance 
the positive values of the pressure peaks of the fuel delivered from the 
fluid outlet 30. There is a fixed frequency relation of the pressure peaks 
because of the fixed rotation of the gear ports by their formation in the 
ring gear 34. 
In addition to the positive pressure pulses, there are time intervals of 
negative pressure in the fluid line leading to the nozzle because of 
interconnection of the fluid outlet 30 to the inlet side of the pump and 
with this structure being shown generally in FIGS. 4 and 5. The arcuate 
passage 60 has a dump timing port 70 extending inwardly therefrom which 
communicates with the outer periphery of the ring gear whereby there is 
periodic communication through a gear port 67 with the fluid inlet port 
27. As seen in FIG. 5, the discharge timing port 65 and the dump timing 
port 70 are oriented whereby both of said ports are never operative at the 
same time. 
The liquid fuel supply system is shown in operative relation with other 
structure in the diagram of FIG. 6. The pump P has the fluid outlets 30 
and 31 connected to an atomization burner nozzle 90 by respective fluid 
lines 91 and 92 each of which have a selectively operable shutoff valve 93 
and 94, respectively, and which lead to a selectively operable system 
shutoff valve 95 having an outlet line 96 extending to the nozzle. If 
pulsed flow is desired, the valves 93 and 95 are opened and the valve 94 
is closed. If continuous flow is desired, the valves 94 and 95 are opened 
and valve 93 is closed. The pump P is driven by a motor 100 having an 
output shaft 101 connected to the pump shaft S through a gearbox 102 which 
has an output shaft 103 for rotating an air blower 104 having an air 
supply line 105 extending into association with the nozzle 90. 
Alternatively, the air blower can be mounted on shaft 101. A variable 
speed controller 110 for the motor 100 provides for varying the rotating 
speed of the fuel pump, either by means of a manual mechanical switch 111 
or by a temperature control 112 which responds automatically to the fuel 
flow requirement. The temperature control 112 is a known system which can 
have inputs, as for example, from an outdoor thermostat 113 and an indoor 
thermostat 114 whereby the control 112 determines the setting of the 
variable speed controller 110 for a desired fuel flow. 
The liquid fuel supply system can supply different rates of pulsed fuel 
flow dependent upon the speed of operation of the pump. The variation in 
the pulsed flow resulting from different pump speeds is shown by comparing 
the graphs of FIGS. 8 and 9 wherein nozzle line gauge pressure is plotted 
against time and with the nozzle line gauge pressure which provides a good 
atomization level being indicated by a broken line 120. A fuel pump may 
normally operate between the speeds of 1400 and 3600 rpm's. The graph of 
FIG. 8 shows the operation, as for example, at approximately 3450 rpm 
wherein a cycle of pulsed flow is indicated by T.sub.1 with that part of 
the cycle having positive gauge pressure being indicated by the interval 
a.sub.1 and with the time occurrence of negative gauge pressure being 
indicated by the interval b.sub.1. The graph of FIG. 9 shows operation at 
a lesser speed, such as approximately 1725 rpm's. The total cycle time 
period has increased approximately 100%, but, due to changes in dynamic 
restrictions to fluid flow in the fuel pump passages, the ratio of on-time 
a.sub.2 to the cycle period T.sub.2 is less than the ratio of on-time 
a.sub.1 to cycle time T.sub.1, therefore producing a lower fuel flow rate 
with the lower fuel pump speed. 
The fuel pump disclosed herein provides a resonant system through use of 
rotatable valve means formed integrally with the pump elements, 
specifically the ring gear, whereby there is a frequency relation between 
the chopping of the pulses and the pressure pulses of the natural gear 
tooth pulsations. In the particular embodiment shown, there is one chopped 
pulse for every other pressure pulse caused by the inner gear tooth 
penetration to provide the resonant system. 
The graph of FIG. 7 shows pressure pulses at various locations within the 
system and which are plotted with respect to time and with zero gauge 
pressure being indicated at the lines 130, 131 and 132. The graph 
represents three pressure conditions, with the uppermost portion of the 
graph showing the pump gear set pressure and, more particularly, the 
pressure pulses created by full mesh of a tooth 37 of the inner gear with 
the space between a pair of teeth in the ring gear. These pressure pulses 
are represented by the curve 133, which is shown to be a curve having 
values both above and below a broken line representing regulated pressure 
and with this line being identified at 134. The second curve 135, shown in 
relation to regulated pressure at 136, represents pressure at the pressure 
port 35 of the pump and is seen to have values both above and below 
regulated pressure and to be 180 degrees out of phase with the pressure 
pulses when the pressure port communicates with the discharge timing port 
65. The third portion of the graph shows the pressure in the nozzle line 
91 as represented by the curve 140 which has pressure peaks 141 in phase 
with the pressure pulses shown by the curve 133 and which are 
substantially above regulated pressure as represented by the line 142. 
The curve 140 of the graph of FIG. 7 shows the peak pressure achieved by 
phasing the natural pump pressure peak pulsation with the peak of the main 
fuel pump pulsation created by communication with the discharge timing 
port 65. As soon as one of the gear ports 67 goes out of communication 
with the discharge timing port 65, the flow of fuel in the discharge 
passage 61 is stopped and, simultaneously, one of the gear ports 67 begins 
to communicate with the dump timing port 70 which allows high pressure 
fluid from the passage 61 to flow back into the fluid inlet 27. This 
results in the relatively steep curve 140 to minimize the time of positive 
pressure below regulated pressure and thus minimize the time below the 
regulated pressure line 142 in order to assure good atomization of the 
fuel oil. 
The graph of FIG. 7 illustrates a system wherein the chopped pulse occurs 
on every third pressure pulse as would occur with a gear port 67 extending 
from every third ring gear root, as shown in FIG. 10. The structure shown 
in FIG. 10 which is the same as that shown in FIGS. 1 through 5, is given 
the same reference numerals with a prime affixed thereto. In the structure 
disclosed, in FIGS. 1 through 5, the chopped pulse occurs on every other 
full mesh pressure pulse and thus establishes pressure conditions as shown 
in the graph of FIG. 3 of the previously mentioned Meyer's application, 
Ser. No. 165,565, and the disclosure thereof is incorporated herein by 
reference.