Fuel measuring and recording systems for combustion devices and method for monitoring fuel flow

A fuel measuring and recording system arranged for use with a fuel system for combustion devices of the type which recirculate unburned fuel back to the fuel system. The present system includes a measuring device which measures fuel flow. Recording apparatus is responsive to the measuring device to make a record of fuel flow. Compensating structure can be used in the measuring system to compensate the measurement for variations in the physical characteristics or temperature of the fuel. Structure for treatment of the fuel may be employed with the fuel measuring system. Another concept of the invention conducts fuel from the measuring device to the combustion device in bypassing relation to the structure for treating the fuel. Also comprising a part of the present invention is a method for monitoring fuel flow whereby a measured amount is determined prior to and bypassing a treatment zone which receives excess fuel and whereby the measured amount is recorded.

BACKGROUND OF THE INVENTION 
This invention relates to a meter for measuring the rate of fluid flow such 
as for determining the rate of fuel usage in an engine. 
The efficient functioning of engines comprises an important factor in the 
operational aspect of trucking firms, marine firms, and other firms which 
use engine driven equipment. These engines are tested periodically for 
output efficiency to determine whether or not repair or overhaul is 
necessary. Various testing methods are used, a common one employing a 
dynamometer. Another method to determine whether the engine is to be 
repaired or overhauled is merely by considering total miles run or hours 
operated. With the use of a dynamometer, or other methods now used, a 
precise analysis of engine condition is not altogether possible because of 
variables which may exist from engine to engine such as ignition 
conditions. 
The most efficient method of determining engine condition is to ascertain 
the amount of fuel consumed by the engine per unit of time. Prior devices 
have not accomplished this method of testing in a commercially feasible 
manner because the meters used, while showing fuel usage, do not give a 
direct reading of the rate that the fuel is used. In prior devices, it is 
thus necessary to make computations from the meter reading, which of 
course is inconvenient and many times inaccurate. Another disadvantage of 
prior devices is that they do not compensate for the expansion or 
contraction of fuel due to variations in temperature, and thus the fuel is 
not accurately metered, particularly in slow flow systems such as fuel 
feed systems for engines. 
Slow flow systems comprise systems using measuring means with slow flow 
accuracy defined by the U.S. Bureau of Standards Handbook 44, namely, 
measuring devices with very slow flow rates and with an accuracy range of 
.+-. 0.6 of one percent throughout the flow range. Although temperature 
conversion tables are available, based on a temperature constant, for 
determining volume of flow, such computing method is often inaccurate and 
always inconvenient. In some cases the use of conversion tables is also 
impractical. 
In view of the above, means heretofore used for determining the condition 
of engines by ascertaining fuel consumption or miles or hours logged are 
not considered to be adequate because such means do not indicate with the 
necessary preciseness the condition of an engine. This may result in 
overhaul or repair which is not necessary, or on the other hand engines 
may remain in operation when in fact they should be overhauled or 
repaired. 
SUMMARY OF THE INVENTION 
It is therefore a primary objective of the present invention to provide a 
meter for use in a fluid flow system which indicates directly the rate of 
fluid flow. Such a meter is particularly adapted for use in conjunction 
with a vehicle engine to show the rate at which fuel is being consumed and 
thus to indicate the mechanical condition of the engine. 
Other objects of the present invention are to provide a meter of the type 
described which includes adjustment means compensating for temperature 
variations; which has a structure wherein indicating means forming a part 
thereof may be remotely located from the drive means of the meter; which 
may be combined with other treating means such as temperature control 
means and bubble removing means; and which includes a lever-operated 
bypass valve capable of either directing fuel through the meter or around 
the meter. 
Additional objects will become apparent from the following description 
taken in connection with the accompanying drawings.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
With particular reference to the diagrammatic view of FIG. 1, an engine is 
designated by the numeral 10 and conventional fuel feed means therefor 
comprising a fuel tank and a fuel line are designated by the numerals 12 
and 14, respectively. 
Forming a part of the present invention is a fuel meter apparatus 16 which 
upon being driven by fluid flow operates in a manner to provide accurate 
information in a direct reading on an instrument to indicate operating 
conditions of an engine, as will be more apparent hereinafter. 
The meter 16 is structurally detailed in FIGS. 2 through 6. It comprises an 
outer casing 18 of cylindrical shape. Casing 18 has a bottom wall 20 with 
projections 21 thereon for a purpose to be described. A sleeve 22, forming 
a cylinder, is disposed within the casing 18. The casing has a head 26 
removably fitted therein. 
As best shown in FIGS. 2 and 4, the casing 18 has an inlet 32 and an outlet 
34 disposed substantially in diametrical relation. The meter apparatus is 
associated with a bypass valve 35 to be described hereinafter which 
preferably is formed with the casing 18 in a common casting. The housing 
for the meter and bypass valve is installed in the fuel line 14 by 
conventional means, with cut ends of the fuel line engaging the bypass 
valve and outlet 34 in the casing 18 by suitable fittings 14a. A 
passageway 36 in the head 26 leads from the inlet 32 and opens into the 
interior of the meter casing, and a passageway 38 also in the head leads 
from the outlet 34 and opens into the interior of the meter casing in 
laterally spaced relation to the outlet of the port 36. A third passageway 
40 extends from a point of inlet interiorly of the meter casing which is 
disposed between the outlet of passageways 36 and 38 to a side of the head 
beyond the sleeve 22, best seen in FIG. 4. The head 26 and the outer 
casing 18 are cut away vertically in the plane of the outer end of the 
port 40 to provide a vertical passageway 42, FIG. 4. This recess 
establishes communication between the passageway 40 and the bottom of the 
casing. It will thus be seen that the passageway 36 leads from the inlet 
32 to the top region of the casing, the passageway 40 leads from the said 
top region to the bottom of the casing, and the passageway 38 serves as an 
exhaust passageway connected to the meter outlet. 
Valve mechanism will now be described to cause the fluid to flow 
alternately to the upper and lower cylinder regions and ultimately be 
exhausted through the outlet 34 for driving plunger means up and down in 
the cylinder. The head 26 has a depending, round center guide post 44 
projecting into the casing at about the center thereof. This post projects 
integrally from the upper wall of a recess 45 cut in the lower surface of 
head 26. Also depending from the head 26 but at the sides, are two guide 
posts 46 and 48 disposed in diametrically opposed relation. Each of the 
posts 46 and 48 is formed with upper and lower flanges 50 and 52, 
respectively, and a central horizontal projection 54 on each side thereof, 
the flanges 50 and projection 54 being arranged to form horizontal slots 
between them which function as guides. Such guide slots are formed on two 
sides of the posts, namely, the front and rear, considering the front to 
be toward the viewer in FIG. 2. 
The two posts 46 and 48 slidably support a valve support plate 56 on the 
front side thereof, best seen in FIGS. 2 and 4. Valve plate 56 has a pair 
of arms 58 on each end slidably received within the slots formed on the 
front side of the respective posts 46 and 48, the valve plate and arms 
being of selected dimension as to be reciprocatable horizontally a short 
distance within the casing. The posts similarly mount a loader plate or 
slide 60 on the other or rear side thereof, this plate also having spaced 
end arms 62, FIG. 5, received in a similar fashion in the post slots as 
are arms 58 of valve plate 56 on the other side, the loader plate and its 
arms also being dimensioned so as to be horizontally reciprocatable a 
short distance. Washers 64, FIGS. 4 and 5, are provided at the front and 
rear of the support posts and are held in place by bolts 66 to maintain 
the plates 56 and 60 within their particular slots of the posts. The 
loader plate 60 has two spaced arms 68 which project substantially at 
right angles from the body of the plate in a forward direction and forward 
beyond the body of the valve plate 56 and below the latter. Attached to 
the portion of the valve plate 56 between the arms on the loader plate 60 
is a trip element 70 projecting both to the front and rear of the valve 
plate in parallel relation to the arms 68. A shaft 72 is supported between 
the arms 68 and also passes slidably through the trip element 70. A first 
compression spring 76 is supported on the shaft 72 between the trip 
element 70 and one arm 68 of the loader plate and a second compression 
spring 78 is supported on the shaft 72 between the trip element and the 
other arm 68. 
Valve plate 56 has a forwardly extending right angle tab or ear 80, FIGS. 2 
and 6, disposed below the region of the outlets of the three passageways 
36, 38 and 40 into the casing, and mounted on such ear is an inverted cup 
valve 82 having a bottom stem 84 freely received within an opening 
provided therefor in the ear. A coil spring 86 is disposed between the ear 
and the cup valve about the stem and holds the valve firmly against the 
underside of the head 26. As illustrated, the valve diameter is such that 
its hollow or recess portion bridges at one time both the outlets from 
passageways 36 and 40 or alternatively both the outlets from passageways 
38 and 40, depending upon the position of the valve in two limit 
positions. 
Slidably mounted on the post 44 is a piston rod 88. This rod has a box-like 
shape, FIG. 6, which provides for slidable connection on the post, and 
projecting rearwardly from the piston rod at the upper end thereof is a 
drive pin or projection 90. Piston rod 88 has a lower transversely 
extending cut-out portion 94, respectively, and post 44 has a cut-out 
portion 96 which as will be more apparent hereinafter is adapted for 
lateral alignment with the cut-out portion 94 at a down position of the 
piston rod. Drive pin 90 projects into an upright angled slot 98 in the 
loader plate, and upon up and down movement of the piston rod, the loader 
plate is cammed first to one side and then to the other. Such movement of 
the loader plate in one direction compresses one of the springs 76 between 
one of the arms 68 and the trip element 70 and in the other direction 
compresses the other spring between the other arm 68 and the trip element 
70. 
Integrally connected to the bottom end of the piston rod 88 is a piston 
100, FIGS. 2 and 6, having a liquid tight or positive seal engagement in a 
suitable manner at its peripheral edge with the inner wall of the sleeve 
22. 
As to the operation of the meter, reference is first made to FIG. 2 wherein 
the piston 96 is disposed at its lower position and the valve 82 connects 
the passageway 36 with the passageway 40. Fluid at this time is directed 
to the bottom of the casing through passageway 42 for lifting the piston. 
As the piston is driven upwardly the fluid above the piston in the casing 
is discharged through the outlet passageway 38. Also during the upward 
travel of the piston, the loader plate 60 is caused to be shifted to the 
right due to the camming action thereon by the drive pin 90, and this 
causes the spring 76 to be compressed since the valve plate 56 is 
restrained from moving correspondingly by engagement of its trip element 
70 with the left side of the piston rod 88 in the area above cut-out 
portion 94. Such upward travel of the piston continues with progressive 
compression of the spring 76 until the bottom cut-out portion 94 of the 
piston rod reaches a height sufficient to allow the trip element 70 to 
pass therethrough, such upper position of the piston being shown in 
phantom lines in FIG. 2. This releases the valve plate for quick movement 
to the right under the action of the loaded spring 76. Since the cup valve 
82 moves with the valve plate 56 it will then be disposed in a position 
connecting passageways 40 and 38. Fluid is then introduced to the upper 
area of the casing through inlet passageway 36 and the piston is driven 
downwardly, the exhaust flow of the fluid at the bottom of the piston 
being driven up through the vertical passageway 42 and out the outlet 
passageway 38. As the piston moves downward, it causes the loader plate 60 
to be shifted to the left due to the camming action thereof from drive pin 
90 and this causes the spring 78 to be compressed. Such downward travel of 
the piston continues until the trip element 70 passes over the top of the 
piston rod 88. Movement of the trip element 70 over the piston rod 88 
allows the spring 78 to move the valve plate 56 to its other position and 
again cause the fluid to be directed under the piston. At this point the 
piston is slightly spaced above the projections 21 of the bottom of the 
cylinder. The cycle described above is repeated continuously as long as 
fuel is supplied to the meter. 
Thus, as the piston reciprocates in its up and down movement, the loader 
plate 60 reciprocates laterally. As a part of the present invention, it is 
desired that the output of the meter be rotational and the structure to be 
described and best shown in FIGS. 4, 5 and 7, is provided to convert the 
lateral reciprocal motion of such loader plate to rotational movement for 
a purpose which will become more apparent hereinafter. The drive pin 90 on 
the piston rod 88 projects beyond the loader plate 60 and is engaged in a 
sinuous type slot 102 in the periphery of an upright barrel cam 104 
disposed adjacent to the rear side of loader plate 60. This cam has 
projecting shaft ends 106 for rotatable support in the casing, the upper 
shaft end extending into a bearing socket 108 in the casing and the lower 
shaft end rotatably engaged in a bore 110 in a U-shaped bracket 112 
secured to the underside of head 26 as by screws 113. The upper portion of 
the barrel cam 104 extends into a recess 114 in the head 26 to accomplish 
proper operation of the drive pin 90 in the cam slot. The cam slot 102 is 
of selected positioning and shape such that as the piston moves up and 
down, the drive pin 90 rotates the cam. The particular shape of the cam 
slot allows the drive pin to move around the ends thereof so that even 
though the pin is reversing direction in up and down movement, or vice 
versa, the cam rotates at a smooth uninterrupted speed. Cam 104 has 
surface projections 115 thereon disposed in spaced relation and having 
peak portions 115a. Engageable with the projections 115 is one or more, 
preferably two in diametrical relation, spring pressed ball assemblies 116 
threadedly supported in the bracket. The spring pressed ball assemblies 
and projections 115 are arranged such that as the drive pin 90 is almost 
to an end or turn portion of the cam slot 102 the spring pressed ball 
thereof rides over the ridge 115 to urge the barrel cam rotatably in its 
forward direction and insure that the drive pin will turn the corner and 
continue into the next segment of the cam slot. 
The upper end of barrel cam 104 integrally supports a drive gear 117 having 
meshing engagement with a driven gear 118 secured on an output shaft 119 
rotatable in the head 26. Shaft 119 is secured to a coupling 120 which 
connects this shaft to a flexible cable 122. Such coupling is contained 
within a fitting 124 having a screw threaded mounting in the head 26. 
With reference again to FIG. 1, as well as to FIGS. 8 and 9, the cable 122 
leads to a tachometer-like instrument 132 having the usual indicating 
needle 134. This instrument is graduated in units 136 which depict fuel 
usage such as gallons or pounds. With proper calibration of the instrument 
132 and lead angle of cam slot 102, an indication is available directly on 
the instrument of the fuel being consumed by an engine per unit of time to 
determine with the utmost accuracy the rate of fuel usage. Such reading 
can be used to determine the general condition of the engine under 
specific load conditions. Units 136 may be graduated for reading in volume 
of fluid per unit of time or weight of fluid per unit of time. 
The tachometer-like instrument 132 includes counter means 138, FIG. 8, for 
permanently recording the volume of fluid used. This instrument may also 
have counter means 140 which similarly shows the volume used per unit of 
time or weight per unit of time but which have reset means 142 for 
resetting the counter means 140 back to zero. Such an instrument, which is 
of well known structure except for the graduated marking thereof, will 
thus indicate the rate of fuel usage and at the same time will record 
accumulated fuel usage and individual tests of fuel usage. With reference 
to FIG. 9, which shows a rear view of the instrument 132, adjustment means 
144 are available for adjusting the operation of the instrument for a 
specific purpose or to correct the accuracy thereof. For example, the 
specific gravity of fuel may vary and it may be necessary to correct the 
accuracy of the instrument as related to the particular specific gravity 
of the fuel. 
The instrument 132 may be mounted closely to the meter 16 or since it is 
operated by a flexible cable it may be mounted at a remote location. The 
present fuel system has the advantage that the meter apparatus 16 may be 
mounted in the engine compartment and the instrument 132 mounted in the 
cab for easy viewing by the driver or by test personnel. 
FIG. 10 shows a system somewhat similar to FIG. 1 with the exception that a 
treatment tank 146 is provided in a line 148 extending from the engine 10 
and connected into the fuel line 14 on the engine side of the meter 
apparatus 16. The system of FIG. 10 is used with an engine 10 of the type 
which returns unburned fuel, such as a Diesel engine. The tank 146 has 
means 150 against which incoming fuel impinges for removing air bubbles 
from the return fuel if any. The tank is vented at 152 for discharge of 
air. Tank 146 in addition to removing bubbles can be used to cool the fuel 
in order that the fuel is fed back to the engine at a proper temperature. 
It is evident from the above description that line 14 constitutes a fuel 
line means for conducting fuel from the meter apparatus 16 to the engine 
10 in bypassing relation to the treatment tank 146. My U.S. Pat. No. 
3,672,394 shows such a tank. It is further evident that the line 14 
constitutes a fluid flow supply line for conducting fuel directly from the 
meter to the engine. 
FIG. 11 shows another system which includes a fuel tank 12, a fuel line 14, 
the metering apparatus 16 in the fuel line 14, and an engine, not shown, 
together with a return line 148 as in FIG. 10. Line 148 may have a 
treatment tank, not shown, similar to tank 146 in FIG. 10, if desired. The 
system of FIG. 11 differs from FIG. 10, however, in that the fuel return 
line 148 from the engine is connected back into the fuel tank instead of 
into the fuel line 14 and such return line includes a second fuel meter 
16a adapted to record the flow of fuel similar to the meter 16. Since 
unburned fuel is returned to the tank 12, the exact amount of fuel 
consumed by the engine will comprise the differential of readings between 
meters 16 and 16a. For this purpose, the outputs from the two meters 16 
and 16a are fed to a proportioning gear box 153 the output of which is fed 
to the tachometer-like instrument 132 by a flexible cable 154. The 
indication on instrument 132 will thus give the rate of fuel consumption 
by the engine. 
FIG. 12 shows still another system which is similar to FIG. 10, employing a 
fuel tank 12 and a fuel line 14 leading between the tank and the engine 
10. The system also employs a return line 148 having a treatment tank 146 
therein. The system of FIG. 12, however, includes temperature control 
means 155, which serves to admit fuel to the engine at a constant 
temperature. Such unit has suitable cooling means controlled by a 
thermistor 156. In the system of FIG. 12, great accuracy of engine 
performance is determined from instrument 132 since the fuel is fed to the 
engine at the most desirable conditions. 
FIG. 13 illustrates an arrangement wherein the fuel meter 16 drives a cable 
122 as in previous embodiments but instead of the cable 122 driving the 
instrument 132 directly said cable leads to a gear box 158 having a dual 
output 122a and 122b in direct ratio drive. The output 122a leads to the 
tachometer-like instrument 132 and the output 122b leads to a recording 
mechanism 160. The recording mechanism is of conventional construction, 
comprising the usual clock driven circular chart on which is recorded by 
means of a stylus the rotative operation of output 122b. By means of this 
system, not only can personnel determine the volume of fuel being used per 
unit of time or weight per unit of time but in addition a permanent record 
is made of the fuel used per unit of time. 
FIG. 14 shows a further extension yet of a concept of the invention. Its 
purpose is to combine the output of a meter of the type described which 
measures fuel usage per unit of time with the output of a speedometer to 
get a resultant reading of fuel usage of distance or revolutions per 
gallon. For example, the output cable 122 from the meter 16 operates a 
sensor 170 and an output cable 172 from a speedometer 174 which is driven 
by the drive shaft of the vehicle or, if used to designate boat engine 
operation, by the propeller shaft, operates a sensor 176. The output from 
sensors 170 and 176 are combined electrically in a voltage or pulse 
divider 178 to get a resultant force on an electrically operated meter 180 
depicting fuel usage per unit of distance. That is, by feeding gallons per 
hour, for example, into sensor 170 from meter 16 and feeding miles per 
hour into sensor 176 from speedometer 174, the resulting output from 
voltage divider 178 will designate miles per gallon, or if for boat 
operation, knots per gallon. Meter 180 has an output for driving a 
recording mechanism 160 of a type previously described. 
FIG. 15 shows a concept of the invention wherein a tachometer-like 
instrument 132' comprises an electrically operated tachometer of well 
known structure. For this purpose, the output shaft 119 supports and 
drives a gear 182 at the upper surface of head 26. Mounted on the head 26 
is an electro-magnetic pickup device 184 of well known structure connected 
electrically to the tachometer-like instrument 132'. Rotation of the 
output shaft 119 is thus transferred electrically to the instrument 132' 
and as in other structures herein the instrument records directly the rate 
of fuel consumption. 
Referring particularly to FIGS. 2 and 3, the bypass valve 35 is cast as an 
integral part of meter 16. It has a hollow interior including a bore 190 
and upper and lower chambers 192 and 194, respectively, on opposite ends 
of the bore. Inlet 32 to the meter leads from upper chamber 192 of the 
valve. Forming the operative part of the valve is a stem 196 of 
considerably less diameter than the bore 190 and movable axially therein. 
Secured to upper and lower ends of the stem are diaphragms 198 and 200, 
respectively, abutting against shoulder portions 202 in the housing. The 
chambers 192 and 194 are closed at the ends by removable walls 204 and 
206, respectively. 
The diaphragms 198 and 200 have tapered hubs 208 and 210, respectively, 
engageable with the end edges of the bore 190 to control the flow of fuel 
through the valve. The arrangement of the parts is such that the stem 196 
and the hubs 208 and 210 are movable axially a short distance, and the 
hubs in such axial movement are arranged to have wedging sealing abutment 
against one or the other of the respective end edges of the bore 190. 
The valve housing has an outlet passageway 214 which extends up from 
chamber 194 to one side and out of communication with bore 190, and this 
passageway communicates with a passageway 216 extending around the valve 
housing and meter casing, FIG. 3, to the outlet 34 of the meter casing. An 
inlet passageway 218 extends from an outer side of the valve housing 
between bore 190 and fuel line 14. 
In the operation of the valve, flow from the inlet passageway 218 and bore 
190 can flow through either the inlet 32 to the meter and out outlet 34 or 
through outlet 214 to bypass passageway 216 and out outlet 34, depending 
upon the position of stem 106. That is, in a down position of the stem as 
shown, fuel from fuel line 14 bypasses the meter by flowing through the 
latter route mentioned above, namely, through passageway 218, bore 190, 
passageway 214, bypass passageway 216 and outlet 34 to the fuel line 14. 
In the up position of the stem, fuel from fuel line 14 flows through the 
meter 16, namely, through passageway 218, bore 190, passageway 32 and 
passageway 36. 
The stem 196 is urged to an upper position by a compression spring 220 
between end wall 206 and the stem wherein normal flow is through the 
meter. However, to position the stem to a down position, a lever 222 is 
mounted pivotally between a pair of ears 224 on top of the valve housing, 
and this lever has a cam end 226 in engagement with a vertical pin 228 
extending slidably through the top wall 204 and abutting against the top 
end of stem 196. In normal metering flow, the lever 222 is thus positioned 
so as to allow the spring 220 to raise the stem. If it should be desirable 
that the fuel flow bypass the meter, the lever is positioned so as to 
lower the stem to the position shown in FIG. 2. 
FIG. 16 shows a somewhat modified form of meter 16'. This meter, similar to 
the meter shown in FIGS. 2-6, has an outer casing 18', a piston 100' and 
mechanism for operating the plunger up and down in reciprocating motion 
which includes the piston rod 88 and the other structure which will not be 
repeated for this embodiment, including the fluid passageway means and 
valve means for causing the reciprocating drive movement of the plunger. 
In the structure of FIG. 16, the piston or plunger 100' comprises a nut 234 
secured integrally to the bottom end of piston rod, and this nut 
threadedly receives a shaft 236 which extends through the bottom wall of 
the casing in a fluid seal 237. The shaft also extends through the piston 
100' and a pair of plates 238 disposed on opposite faces of the piston. 
These plates have arcuate or bulbular portions 240 and are constructed of 
metal having a high coefficient of expansion, whereby upon variation in 
temperature the arcuate portions expand away from and contract toward the 
piston. The piston carries an outer gasket 242 to provide sealing 
engagement with the inside surface of the casing, and the outer peripheral 
edges of the plates 238 extend a flange portion 244 of the gasket and the 
piston. The diameter of the plates 238 is slightly less than the diameter 
of the piston to allow for lateral adjustment of the peripheral edge of 
the plates upon expansion and contraction. 
Threadedly mounted on the shaft 236 on the bottom side of the piston and on 
the outside of the bottom plate 238 is a nut 246. The two threaded 
portions of the shaft 236 which engage the respective nuts 234 and 246 
have opposing thread in an arrangement such that when the shaft 236 is 
turned on one direction the nuts draw the plates inwardly toward each 
other and upon rotation of the shaft 236 in the opposite direction the 
bulbular portions of the plates are moved apart. Compression springs 248 
maintain the bulbular portions of the plates outwardly against the 
respective adjusting nuts. 
The projecting end of shaft 236 carries a knob 250 which as best seen in 
FIG. 17 is associated with graduation marks 252 provided on the bottom of 
the casing 18'. Such graduation marks indicate adjusted rotative positions 
of the shaft 236 in the positioning of the bulbular portions 240 of the 
plates 238 relative to the piston 100' for a purpose to be described 
hereinafter. 
As was described hereinbefore in connection with the structure of FIGS. 
2-5, the piston is operated by fluid in a reciprocating motion for driving 
indicating or counter means. In such reciprocating action, it drives a 
selected amount of fluid from areas on each side thereof. The structure of 
FIG. 16 automatically adjusts itself to meter accurately even though the 
volume of the fluid therein changes due to a variation in temperature. 
That is, the plates 238 have specific expansion and contraction 
characteristics such that when the fuel is warmer than a set constant, 
they expand away from the piston 100 to reduce the volume of the area in 
which the stroke of the piston occurs. By correlating the expansion 
characteristics of the plates 238 and the expansion characteristics of the 
fluid, exact metering is accomplished. If the liquid should cool below the 
constant, the plats 238 contract to enlarge the areas in which the piston 
operates. The expansion characteristics of fluids of different specific 
gravities may vary, and for this purpose the shaft 236 may be rotatably 
adjusted by knob 250 to position the plates 238 according to well known 
characteritics of expansion and contraction of various liquids. A proper 
setting of the knob 250 as determined by the specific gravity of the fuel 
being metered will provide accurate results. 
In the embodiment of FIG. 16, the head 26' of the meter is altered relative 
to the structure of FIG. 1 to the extent that it contains a counter 
mechanism 256 of conventional construction operating on a shaft 258. One 
end of the shaft has a bevel gear 260 secured thereon and according to the 
present invention, the output shaft 119 instead of projecting through the 
head as in FIG. 5, has a bevel gear 262 thereon in mesh with the bevel 
gear 260 for driving the counter mechanism 256. The head 26' has a 
removable cover 264 with a transparent or window portion 266 for viewing 
the counter. 
FIG. 18 is a fragmentary section view of a portion of the head 26' and 
shows an embodiment wherein an end of shaft 258' of the counter mechanism 
256 has a coupling 268 with a flexible shaft assembly 270 which leads to a 
remote counter system or a tachometer-like instrument 132 of the type 
previously described. By means of the structures of FIG. 18 remote counter 
means may be made available in addition to the counter 256 so that even 
though the meter is mounted in the motor well of a vehicle, the counter 
can be located in the cab. 
FIG. 19 shows a modified structure of the barrel cam 104'. The cam of this 
embodiment, while having the same slot structure and operation as 
described in connection with FIG. 7, employs leaf springs 274 at the ends 
of the cam slot 102. These springs are positioned to one side of the slot 
end, such positioning being on the side in which the drive pin is 
advancing. They are arranged such that when the pin has passed the spring, 
it is advanced around the turn and cannot travel back in the same segment 
of the slot. As the pin springs past springs 274, the cam is also urged 
forwardly so as to rotate smoothly and without interruption when the drive 
pin is at the turn. 
SUMMARY 
According to the present invention, a fuel system is provided which allows 
operators to not only operate an engine in the most efficient manner but 
also to examine fuel usage to test the condition of the engine. That is, 
by viewing on the instrument 132 the volume of fuel being used per unit of 
time or weight per unit of time under a particular load condition, a most 
efficient method is available of directly ascertaining engine efficiency 
and consequently whether or not the engine needs repair or overhaul. Such 
method has important advantages over other types of engine tests because 
an accurate knowledge of fuel consumption based on a particular load gives 
a direct indication without variables of the engines'condition. 
The system of FIG. 12 is even more accurate in that the fuel is always fed 
to the engine at optimum conditions for greater efficiency. The structure 
of FIG. 16 wherein adjustment is made for the temperature of the fuel 
provides for even greater efficiency, and it is to be understood that such 
type of meter can be used with any of the systems disclosed herein. 
Adjustment of the expansion means in the meter of FIG. 16 according to the 
specific gravity of the fuel is accomplished by adjusting knob 250. In 
connection with the embodiment of FIG. 16, the output shaft 258' can drive 
a flexible cable assembly 122 as in the embodiment of FIGS. 2-5 wherein 
the meter casing 18' can be placed in the motor well and the indicator or 
counter means driven thereby can be placed in the cab or other place which 
is convenient for inspection. 
The present invention may be used in conjunction with almost any engine of 
the fuel burning type such as automotive, marine or stationary engines. 
The throttle of an engine may be set by use of the present rate meter 
rather than by revolutions per minute. 
It is to be understood that the forms of my invention herein shown and 
described are to be taken as preferred examples of the same and that 
various changes in the shape, size and arrangement of parts may be 
resorted to without departing from the spirit of my invention or the scope 
of the subjoined claims.