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Патент USA US2114565

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Àpriä 19A, H933,
F KOVACH
@Elli-,5
FUEL INJECTION PUMP
Filed July 13, 1935
2 Sheets-Sheet 2
Vœcá
Patented Apr. 19, 1938
2,114,565
AUNITED STATES PATENT GFFICE
l
2,114,565
FUEL INJECTION PUMP
Frank Kovach, Lincoln,- Nebr., assignor of one-v
half to H. V. Martin, Lincoln, Nebr.
`
Application July 13, 1935, Serial No. 31,267
4 Claims.
(Cl. 103-37)
This invention relates to pumps and more par
of a plurality of plungers Il) reciprocably mount
ticularly to the control of the stroke and the
speed of the. pistons of reciprocating pumps,
ed in bores I2 in a cylinder block i4 bolted as
at I6 to the top of a cam shaft and tappet cast
especially for oil and Diesel engines.
ing or housing i8. Springs 20 keep the base
of the plungers in contact with the adjustable
ends of roller tappet units 22 and thus keep the
»
'I'he primary object of the invention is to pro
vide an extremely simple and accurate device
for precisely controlling the effective stroke of
reciprocating pumps. Incidentally an object of
the invention is to reduce the number of parts
in such controls to about the same as that re
quired for a fixed output pump.
Another object is to provide an extremely
sturdy feed control for fuel injection pumps par
ticularly for high speed oil and Diesel engines,
which control may be varied micrometrically
over a full range without seriously affecting the
timing.
Another object is to combine in one simple
unit a device which not only controls the amount
of the fuel charge but which also and at the
same time varies the rate of fuel injection and
rollers 24 of these units in contact with the cams
26 on the cam shaft 28 which shaft is mounted
in the end walls 30 of the cam chamber 3| in
the lower part of the casting i8 in a novel man 10
ner to be described farther on. The tappet
chamber 32 is provided with a removable cover
34 to permit inspection and adjustment of the
tappet units and piston springs.
Thus far the pump is in general no different 15
from the usual well known constant feed, con
stant stroke pumps of this type. The preferred
form of my invention is obtained by providing
the novel bearing unit 36 which carries the f
bearings 38 of the cam shaft. The unit consists
of two circular members 40 rigidly secured to
yet approximately maintains the timing.
The_rate at which the fuel is injected into
gether as by the bar t2 whereby they may be
oil and Diesel engines is of extreme importance
in its effect on smooth running and eiliciency.
As is well known, this rate can be easily con
nals M in the end Walls 30, or by removal of
caps 46 and 4W the unit and cam shaft may be
trolled for wide open throttle by properly design
ing the pump cam but the rate so obtained may '
be and usually is wrong for the lower range of
By my invention I am able
to use the cam designed to give maximum eili
ciency at full throttle for all rangesl of throttle
30 throttle settings.
settings. I accomplish this by providing simple
means for displacing the cam shaft from the
line of motion of the cam follower which acts
on the pump piston. The preferred path of dis
placement is such that altho the _effective stroke
is decreased the rate of fuel injection is in
creased, thus compensating for any bad effect
40 the fixed cam shape may have at lower throttle
openings.
In the drawings:
Figure 1 is a' view of the pump looking at it
from the control end.
45
Figure 2 is a longitudinal vertical section taken
on line 2--2 of Figure l. -
Figure 3 is a transverse vertical section taken
on line 3-3 of Figure 2.
Figures 4, 5, 6 and 'l are diagrams showing the
50 control set respectively at full throttle, half
throttle, -idling and stopped.
Figure 8 is a diagrammatic view showing my
improved pump connected to an engine.
The fuel injection pump shown in Figures 1,
65 2 and 3 used to illustrate my invention consists
turned as one in the circular openings or jour.
bodily removed from the casting.
The bearings 38 are eccentrically mounted in
the circular members 40 whereby, as the unit is
_turned by means of the lever or, governor arm
48, the relation of the cam shaft to the tappet 30
rollers is changed as will be clearly understood
by reference to Figures 4 to 7. This causes a
change in the clearance of the piston heads, or,
what in effect amounts to the same thing, it
causes a change in the effective stroke of the
pump since the effective stroke is measured» by
the distance between the highest position of the
plunger end and the top of the fuel inlet port Sil.
Each of the inlet ports 50 communicates with a
common bore 52 which may be provided with a
-shut-off valve 54 at one end and a connection 55
at the other end for connection with a supply
pipe not shown. Each pump outlet p_ort 56 is
provided with means 5l for connecting with a
conduit 58 ‘for carrying the fuel charges to the
respective engine cylinders in the usual manner.
The cam shaft 28 may be driven from the
engine crank shaft in any manner which permits
unimpeded rotation of the bearing unit 36, the
only requirement being that the connections
used be positive so that the gear ratio between
the engine and the cam shaft is maintained.
One method of driving the cam shaft is shown
diagrammatically in Figure 8 in which the crank
shaft 60 of the engine 6i is connected for exam- K,
2,114,565
ple, by a chain $2 to drive a shaft ll of the re
duction gear unit 64 mounted on the engine.
the bearing unit laterally of and in a plane nor
mal to the piston axis at one-half throttle.Í
The gear unit is connected to one end of the cam
Now instead of dropping the cam shaft straight
down assume it to be moved in a lateral path,
shaft 28 thru a relatively long shaft C! with one
or more universal joints 66 and 61. I do ,not
wish to be limited to any specific manner of driv
ing the pump and give this merely as an exam
such. for example, as the arcuate path 12, Fig
ures 4 to 7, and in the direction indicated by the
arrow 69, until the effective stroke is one-third
ple. It will be quite obvious that my improved f maximum at which point the charge is one drop.
pump may be .applied to almost any type of oil or
10 Diesel engine and, of course, its specific drive
will >depend upon the design of engine on which
it is installed.
~
The operation of the pump control will be
easily' understood by reference to Figures 4 to 7.
15 'I'he arrow 68 shows the direction of rotation of
the cam shaft and the arrow 69 shows the direc
tion of rotation of the bearing or control unit ß
from a point of full throttle as illustrated in Fig
ure 4 to a point of stop as illustrated in Figure 7.
20
At full throttle (Figure 4) the cam shaft axis,
the bearing unit axis and the piston axes al1/lie
in the same plane with the result that the effec
tive stroke oi' the pump is at a maximum. Now
moving the governor arm 48 in the direction of
25 arrow 69 the effective stroke of the pump is de
creased to about half when the arm has moved
about 45° (Figure 5) and nearly a minimum
when the arm has moved approximately 60°
(Figure 6) and finally to zero as the arm reaches
30 between 70° and 80° depending on the design of
the parts. Incidentally it will be ,apparent to
those skilled in the art that the governor arm
40
parent that the speed of the pump piston per 10
degree of cam shaft rotation is appreciably in
creased by the lateral displacement of the cam
shaft from the center line of thev tappet. 'I'hus ’ f`
the slower the engine turns over, due to de- >
crease in fuel charge, the faster the reduced 15
charge is injected in fewer degrees of cam shaft
rotation -than one drop of the maximum charge.
'I‘he timing loss due to the dropping of the cam
shaft is partly compensated for by the cam be
ing displaced laterally from the center line of 20
the tappet, which makes the cam engage the
roller as many degrees sooner as was lost by
the effective plunger stroke due to the drop of
the cam shaft.
\
Thus it will be seen that by my invention I 25
have provided an extremely simple control for
simultaneously reducing the fuel charge and in
creasing the rate `of fuel injection while at the
same time maintaining the timing not far from
constant. It will also be seen that I elimi 30
nate the usual series of gears and levers and
that all the elements employed such as bear
by a combination of these as desired.
ings and bearing supports are solids of rotation
thus not only reducing the ‘cost of production to
a minimum but also reducing the possibility of 35
Astudy of Figures 4 to 'I will show that three
objects result from my extremely simple control.
curate machining, setting and adjustment.
First, I regulate the quantity of the fuel charge '
ings in a rotatable bearing unit is the preferred
48 may be connected to be moved by the engine
35
From a study of the cam action it will be ap
governor or by a foot or hand throttle lever or
injected per stroke. Second, I regulate the rate
of the injection of each fuel charge and, third,
I substantially maintain the timing of the in
jections. The regulation of the quantity or size
of the fuel charge will be obvious -but the regula
tion of the rate of injection and the approxi
45
mate maintenance of the timing _are not easily
appreciated and will therefore be explained.
To illustrate, let us assume the quantity lof fuel
injected »into the engine at full throttle, i. e., at
50 maximum effective stroke (Figure 4) to be, for
example, three drops. Assume further that the
cam is so shaped that the ñrst drop is injected
in ten degrees of cam shaft rotation, the sec
ond in ten degrees of rotation and the last drop
55 _in ten degrees of rotation, under which condition
the rate of injection is constant. Now assume
that the cam is dropped in a straight line (so
as not to move out of the center line 1I of the
tappet, Figure 4) until the effective stroke is one
60 third that at _full throttle, i. e., the pump will in
ject orie drop per stroke.
Altho the size of the
charge has been reduced the rate of injection
has not been changed since the entire eñective
stroke will take place in the last 10° of cam shaft
65 rotation exactly the same as the last third of the
effective stroke at full throttle.
The rate of
injection, namely,.ten degrees per drop, has not
been changed by the vertical displacement of the
cam shaft in the straight line 1I. Since the
70 pump piston stroke per degree of cam shaft ro
tation has not been affected through the throttle
range, the rate of fuel injection remains constant
_and depends solely upon the shape of the cam.
A substantially vertical movement oi.’ ‘the cam
75 shaft could be obtained by locating the axis of
non-uniform wear and making possible very ac
The eccentric mounting of the cam shaft bear
embodiment of my invention but I do not wish to 40
be limited to this specific construction since a
little study will show that the invention in its
broadest aspects may be carried out in an in
finite number of Ways as, for example, replacing
the arcuate path 'l2 by a path of any desired 45
shape including straight lines (inñnite eccen
tricity) at any desired angle to the line of mo
tion of the tappet. It will also _be apparent to
those skilled kin this art that for any given engine
the design of the cam will depend on the shape 50
and direction of the path of cam shaft displace
ment chosen.
Or for any given cam and engine
the choice of the path of displacement will de
pend upon the kind of engine operation that may
55
Y be desired.
What I claim is:
.
1. Afuel pump for Diesel engines comprising
a housing having a cam shaft chamber and a
tappet chamber above the cam shaft chamber,
a horizontal wall between said chambers having 60
vertical bores, a plurality of tappets in said bores
and having adjustable upper ends, the upper wall
for said tappet chamber having bores arranged
coaxially of said tappet bores, a cylinder block
removably but tlxedly secured to said housing and
having cylinder bores located coaxially of said
coaxially arranged bores, said cylinder bores hav
ing fuel inlet and outlet ports, pistons in said
cylinder bores acting as slide valves to control
said inlet ports and projecting into the tappet
chamber for engaging the adjustable upper ends
of said tappets, springs around the respective
pistons for maintaining said engagement, said
65 J
cam shaft chamber having a pair of alined bores
in the end walls. bearing supports rotatably
1
2,114,565
mounted in the alined bores, bearings eccentrical
ly lcarried in the supports, means within the
chamber rigidly connecting said supports to
gether for maintaining the bearings in coaxial
relation and for .rotating the supports as a unit,
a cam shaft in said bearings and having cams for
3
having fuel inlet and outlet ports, spring pressed
pistons in said cylinder bores acting as slide
valves to control said inlet ports, and projecting
into the tappet chamber for operatively engag
ing said tappets, said cam shaft chamber having
a pair of alined bores in the end walls, bearing
ut
engaging the tappets, means for preventing axial
supports rotatably mounted in said alined bores,
movement of the cam shaft, said preventing
bearings eccentrically carried in the supports,
means rigidly connecting said supports together
for maintaining the bearings in coaxial relation 10
means being removable for permitting the re
10 moval and insertion of the supports and cam
shaft as a single unit, said tappet chamber hav
ing a removable side wall for permitting access
to adjust said tappets and for moving the tappets
to clear the cams during the insertion or removal
15 of said cam shaft unit.
2. A fuel pump for Diesel engines comprising
a housing having a wall separating the interior
into‘a cam shaft chamber and a tappet chamber,
said wall having tappet bores therein, a plu
20 rality of tappets in said bores, a cylinder block
ñxedly secured to said housing and having cylin
der bores located coaxially of said tappet bores,
said cylinder bores having fuel inlet and outlet
ports, pistons in said cylinder bores acting as
and for rotating the supports as a unit, a cam
shaft in said bearings and having cams opera
tively engaging the tappets, and means prevent
ing axial movement of said supports and the cam
shaft carried thereby, said preventing- means be
15
ing removable for permitting the removal and
insertion of said supports and cam shaft through
either one of said alined bores as a single unit. ,
4. A fuel injection pump for oil engines com
prising a cylinder block having a pump bore and 20
a cam chamber, said bore having fuel inlet and
outlet ports, rigidly connected bearing supports
rotatably mounted in two opposite walls of said
chamber, bearings eccentrically mounted in said
slide valves to control said inlet ports, and pro
supports, a cam shaft carried in said bearings, 25
jecting into the tappet chamber for operatively a cam on said shaft, a piston in said bore oper
engaging said tappets, springs 4associated with- a'tively associated with said cam, and acting as
the respective pistons for maintaining said en
gagement, said cam shaft chamber having a pair
30 of alined bores in the"end walls, bearing sup
ports rotatably mounted in said alined bores,
bearings eccentrically carried in the supports,
means rigidly connecting said supports together
for maintaining the bearings in coaxial relation
'Xx' and providing for rotation of the supports as a
unit, a cam shaft in said bearings and having
cams operatively engaging the tappets, and
means preventing axial movement of said unit,
said preventing means being removable for per
mitting the removal and insertion of said sup
ports with the cam shaft through one of said
alined bores as a single unit.
.
3. A fuel pump for Diesel engines comprising
a housing having a horizontal wall separating the
interior into a cam vshaft chamber and a tappet
chamber, said wall having vertical tappet bores
therein, a plurality of tappets in said bores, a
cylinder block removably but ilxedly secured to
said housing and having cyllnder‘bores located
‘ coaxially of said tappetbores, said cylinder bores
a slide valve for said fuel inlet port, said cam
shaft, shaft bearings and bearing supports being
inclosed in said chamber thereby being free from 30
dust and dirt, said cam shaft being positioned be
tween the piston and the support axis at maxi
mum eñ'ective stroke, vvwhereby when the cam
shaft is in said maximum stroke position the cam
shaft axis and support axis are both intersected
by an extension of the piston axis, and means
connected to said bearing supports for rotating
lsaid supports any desired number of degrees in a
predetermined range of approximately 75° from
said maximum effective stroke position, so that 40.
as the cam shaft starts toshift from said posi
tion its motion is substantially all lateral and its ,
vertical component of motion is substantially
zero but as the shaft approaches its no load posi
tion at the end o! said range of 75° its lateral
component of motion is of negligible value while
said vertical component approaches the value the
lateral component had at maximum effective
stroke position.
'
FRANK KOVACH.
50
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