U.S. patent number 3,880,131 [Application Number 05/374,732] was granted by the patent office on 1975-04-29 for fuel injection system for an internal combustion engine.
This patent grant is currently assigned to The Bendix Corporation. Invention is credited to Russell William Twaddell, Edwin Ben Watson.
United States Patent |
3,880,131 |
Twaddell , et al. |
April 29, 1975 |
Fuel injection system for an internal combustion engine
Abstract
Fuel injection apparatus for an internal combustion engine in
which separate electro-mechanical control valves are operated to
begin and end each fuel injection period in timed relation to the
internal combustion engine by closing off the spill path to begin
an injection period and by opening the spill path to end the
injection period.
Inventors: |
Twaddell; Russell William
(Sidney, NY), Watson; Edwin Ben (Sidney, NY) |
Assignee: |
The Bendix Corporation (Sidney,
NY)
|
Family
ID: |
23478000 |
Appl.
No.: |
05/374,732 |
Filed: |
June 28, 1973 |
Current U.S.
Class: |
123/500 |
Current CPC
Class: |
F02M
41/06 (20130101); F02M 41/1405 (20130101); F02M
59/366 (20130101) |
Current International
Class: |
F02M
41/14 (20060101); F02M 41/08 (20060101); F02M
59/20 (20060101); F02M 59/36 (20060101); F02M
41/06 (20060101); F02M 41/00 (20060101); F02m
039/00 () |
Field of
Search: |
;123/139R,139E,139AB,139AR,139AD,139AE,14R,104 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Burns; Wendell E.
Attorney, Agent or Firm: Hartz; S. H.
Claims
What is claimed is:
1. A fuel injection system for an internal combustion engine having
a pumping unit for pressurizing fuel;
a distributor connected to the pumping unit and receiving fuel
under pressure from the pumping unit for delivery in timed sequence
to the engine; and
a pair of electro-magnetic valves receiving fuel under pressure
from the pumping unit and connected to a spill path, and means for
providing electrical signals in timed relation to the engine to
operate one valve to close the spill path to begin a fuel injection
period to the engine and to operate the other valve to open the
spill path to end the fuel injection period.
2. A fuel injection system as described in claim 1 in which only
two electro-magnetic valves are required irrespective of the number
of cylinders in the engine.
3. A fuel injection system as described in claim 1 in which both
valves are closed during the fuel injection period.
4. A fuel injection system as described in claim 3 in which both
valves are energized during a fuel injection period.
5. A fuel injection system as described in claim 1 in which the
means for pressurizing the fuel are reciprocating pistons operated
by a cam in timed relation to the engine to periodically pressurize
the fuel during a fuel injection period.
6. A fuel injection system as described in claim 1 in which the
means for providing electrical signals comprises a rotor timed to
the engine crank shaft and a plurality of trigger coils associated
therewith.
Description
The invention relates to fuel injection apparatus for internal
combustion engines and more particularly to apparatus in which fuel
is injected into the cylinders of the engine under the control of
electro-mechanically operated fuel injection valves.
The present invention has all the advantages of co-pending
application Ser. No. 260,882 now U.S. Pat. No. 3,779,225, and in
addition avoids the requirement of fast acting solenoid operated
control valves for controlling the amount of fuel dispensed by a
reciprocating piston pressure pump. In the arrangement described in
the co-pending application a single solenoid operated control valve
controls the injection period. In the present application separate
electromagnetic control valves control the beginning and end of the
fuel injection period in timed relation to rotation of the cam
shaft or crank shaft of the internal combustion engine.
By using two valves in the manner described briefly above, the time
interval for operation of any one valve in an eight cylinder engine
is 2.88 milliseconds when the engine is at fast idle at 2600 rpm;
whereas when only a single valve is used the valve must open and
close in 0.15 milliseconds.
The present invention has further advantages over the apparatus
described in copending application Ser. No. 260,882, now U.S.
Patent No. 3,779,225, in that the apparatus of the present
invention uses a distributor for periodically connecting the high
pressure pump to the delivery valves in timed relation with the
internal combustion engine and only two electromagnetic valves are
needed in the present apparatus for controlling the injection
period. One valve starts the injection period and the second valve
ends the injection period.
The invention contemplates a fuel injection system for an internal
combustion engine having a pumping unit for pressurizing fuel, a
distributor connected to the pumping unit and receiving fuel under
pressure from the pumping unit for delivery in timed sequence to
the engine, and a pair of electro-magnetic valves operated in timed
relation to the engine and receiving fuel under pressure from the
pumping unit and connected to a spill path, the valves being
arranged so that one valve closes the spill path to begin a fuel
injection period to the engine and the other valve opens the spill
path to end the fuel injection period.
One object of the present invention is to provide fuel injection
apparatus which avoids the use of fast acting magnetic valves.
Another object of the invention is to use separate electro-magnetic
control valves to begin and end the fuel injection period and to
use only two valves regardless of the number of cylinders in the
engine.
These and other objects and advantages of the invention will appear
more fully hereinafter from a consideration of the detailed
description which follows, taken together with the accompanying
drawings wherein two embodiments of the invention are illustrated
by way of example. It is to be understood, however, that the
drawings are for the purpose of illustration only and are not a
definition of the limits of the invention, reference being had to
the appended claims.
IN THE DRAWINGS
FIG. 1 is a side view partly in section of a fuel injection pump
constructed according to the invention,
FIG. 2 is an end view thereof with a portion in section,
FIG. 3 is a vertical section taken approximately on the line 3--3
of FIG. 2 and shows one of the electro-magnetic valves in
detail,
FIG. 4 is a timing chart showing sequence of operation of the
electro-magnetic valves in the four cylinder pump of FIGS. 1 to
3,
FIG. 5 is a longitudinal section of a second embodiment of a fuel
injection pump constructed according to the invention,
FIG. 6 is an end view showing the cap at one end of the pump shown
in FIG. 5,
FIG. 7 is an end view of the pump shown in FIG. 5 with the cap and
rotor removed, and
FIG. 8 is a timing diagram for a four cylinder pump as shown in
FIGS. 5 to 7.
The fuel injection pump shown in FIG. 1 and constructed according
to the invention is intended for use on a four cylinder, four
stroke, diesel engine although the pump can be adapted to either
diesel or stratified charge engines of two or four stroke design
with any practical number of cylinders.
The fuel injection pump shown in FIG. 1 has a cam shaft 3 which is
driven for a four-stroke engine, by the engine at one-half engine
speed. A high pressure pumping unit 1 has a plunger 4 which
reciprocates in a pumping chamber 4A. Plunger 4 is driven by cam
shaft 3 through a cam and cam follower in the usual manner. A
transfer pump 2 connected to a fuel tank (not shown) delivers fuel
to pumping chamber 4A through an inlet port 4B. The fuel in pumping
chamber 4A is pressurized by reciprocation of plunger 4 and is
pumped through a check valve 5 and passages 6 and 7 to passages 8
and 9.
A distributor rotor 10 is driven by cam shaft 3 and connects
passage 9 sequentially to delivery valve assemblies 30A, 30B, 30C
and 30D to which high pressure lines to each engine cylinder are
connected. High pressure lines (not shown) are connected to nozzle
holder assemblies (not shown) for each cylinder. A plurality of
slots 11A, 11B, 11C and 11D are spaced about the periphery of rotor
10 and communicate with passages 12 and 13 and port 14 in rotor 10.
Passages 15A, 15B, 15C and 15D are connected to delivery valve
assemblies 30A, 30B, 30C and 30D, respectively. As rotor 10 rotates
slots 11A, 11B, 11C and 11D in rotor 10, register in sequence with
passage 9, and port 14 in rotor 10 registers in sequence with
passages 15A, 15B, 15C and 15D (FIG. 2). Fuel flows from passage 9
through a registering slot 11A, 11B, 11C or 11D, passages 12 and 13
and port 14 to passage 15A, 15B, 15C or 15D, respectively, and to
the associated delivery valve 30A, 30B, 30C or 30D, respectively,
for injection into the associated cylinders.
Fuel is delivered under pressure to the delivery valves only for
that period of the actual injection which is controlled by two
electro-magnetic valves 16 and 16A (FIG. 2). The purpose of the
valves 16 and 16A is to spill to a low pressure region, all the
fuel being delivered by pumping unit 1 except during the short
injection period which may vary between 1.5 milliseconds at full
load operation to as little as .15 millliseconds at fast idle,
depending on such factors as engine speed, number of cylinders,
etc. Each of the valves when deenergized is open and connects
passage 8 to spill passage 28 connected through spill outlet 46
(FIG. 2) to the fuel tank. One valve begins the injection period by
closing the spill path and the other valve ends the injection
period by opening the spill path.
When valve 16 is in the energized closed position as shown in FIG.
1, fuel under pressure in passage 8 in communication with annulus
21 is blocked and fuel cannot flow through valve 16 to spill
passage 28. Similarly, valve 16A when energized is closed so that
passage 8 is not in communication with spill passage 28. Thus, when
both valves 16 and 16A are energized simultaneously fuel is
delivered to one of the cylinders during this time as determined by
the angular position of the distributor rotor 10. At the end of a
delivery period valve 16 is deenergized and plunger 17 moves to the
open position as shown in FIG. 3 so that annulus 21 communicates
with groove 22 in the plunger and annulus 27 in communication with
spill passage 28 communicates with groove 26 in the plunger.
Grooves 22 and 26 are connected by a port 23, a passage 24 and a
port 25. Fuel flows from annulus 21, through groove 22, port 23,
passage 24, port 25 and groove 26 to annulus 27 through passage 28
and spill outlet 46 to the fuel tank.
A timing diagram for operating electro-mechanical valves 16 and 16A
(referred to as valves 1 and 2 in the diagram) under full load at
2500 rpm and at fast idle at 2600 rpm is shown in FIG. 4. At zero
degrees injection into cylinder A starts when valve No. 1 closes
since valve No. 2 is in closed position having been energized
earlier by a power pulse. Under full load at 2500 rpm, injection
terminates at 10.degree. when valve No. 2 is deenergized and
returns to open position. At 45.degree. valve No. 1 opens and both
valves are open until 55.degree. whereupon valve No. 2 closes. At
90.degree. valve No. 1 closes and fuel is injected into cylinder B
for 10.degree.. At 100.degree. valve No. 2 again opens and
terminates the injection period. The valves continue to operate in
this sequence as shown in FIG. 4 under full load at 2500 rpm. Each
injection period lasts 10.degree. or 1.33 milliseconds and each
valve operates every 45.degree. or 5.98 milliseconds.
When the engine is operating at fast idle at 2600 rpm, at 0.degree.
valve No. 2 is closed and valve No. 1 is operated to closed
position to start the injection period to cylinder A. At
11/2.degree. valve No. 2 opens and ends the injection period to
cylinder A. At 45.degree. valve No. 1 opens and at 461/2.degree.
valve No. 2 closes. At 90.degree. valve No. 1 closes and begins an
injection period to cylinder B which is terminated at 911/2.degree.
upon opening valve No. 2. This sequence is continued for cylinders
C and D. The injection periods at fast idle at 2600 rpm are
11/2.degree. or 0.192 milliseconds and each valve operates every
45.degree. or 5.76 milliseconds.
Valves 16 and 16A are energized by signals timed to the angular
position of the engine crank shaft. The signals may be advanced
mechanically or electronically as a function of engine speed if
desired. The signals are converted to power pulses by a suitable
electronic circuit (not shown) and the duration of the power pulses
may be varied as a function of engine parameters and ambient
conditions so that the power pulses energize the electro-magnetic
valves 16 and 16A to supply the correct quantity of fuel required
by the engine for desired operation. The power pulses must precede
valve operation by a reaction time which is a function of the
electro-magnetic circuit characteristics, physical properties of
the valve, friction spring characteristics, etc.
The signals for energizing valves 16 and 16A are generated by a
disk 38 of ferrus material having either a slot or projection in
its periphery and rotated by cam shaft 3 (FIG. 1). Coils 41 are
radially disposed about the periphery of disk 38 so that the
signals are induced in the coils and are angularly timed with the
engine crank shaft. The signals are transmitted by conductors 40 to
the electronic circuit for conversion to power pulses. The power
pulses are applied to conductors 29 connected to solenoid coils 20
on valves 16, 16A as shown in FIG. 3. An armature 19 connected to
plunger 17 is magnetically attracted to the fixed pole of the
solenoid when coil 20 is energized. A conical engagement of the
armature and fixed pole is employed to increase the stroke - air
gap ratio and solenoid efficiency. When plunger 17 moves through a
portion of its stroke and has reached a high speed, communication
between annulus 21 and annulus 22 is suddenly interupted and high
pressure fuel is permitted to flow from passage 9 through delivery
valve 30A to engine cylinder A as previously described. Fuel
delivery to the engine cylinder is suddenly terminated when the
power pulse is removed from either coil 20 as plunger 17 is moved
by a spring 18 to its open position in which annulus 21
communicates with spill outlet 46 and pressure in passage 7 is
reduced below that required to hold delivery valve 30A open.
Any fuel that might leak around plunger 17 finds its way into
cavity 44 or cavity 42 which are connected with leakage return
fitting 39 through passages 45, 31, 32 and 33. Likewise any fuel
leaking from distributor 10 passes to cavity 34 which communicates
with the leakage return fitting 39 through passage 35, cavity 36,
ports 37 and passages 32 and 33. Leakage return fitting 39
communicates with the fuel tank.
While the invention is embodied in a four cylinder pump any type of
pump capable of supplying uniform high pressure fuel flow at a rate
equal to or greater than the instantaneous engine fuel requirement
may be used. Even a pump having a lower flow rate can be used with
a suitable accumulator.
FIGS. 5, 6 and 7 show a second embodiment of the invention which
operates in the same manner as the embodiment shown in FIGS. 1, 2
and 3, the main difference being in the high pressure fuel supply
pump. The embodiment of FIGS. 1, 2 and 3 uses an in-line high
pressure fuel supply pump whereas the embodiment of FIGS. 5, 6 and
7 uses a distributor type pump. Other minor differences will be
apparent from the following description.
Referring to FIG. 5, the fuel injection pump shown therein has a
rotating distributor 106A having plungers 102 which are
simultaneously displaced in a radial direction by a stationery
internal cam 103 to supply fuel under high pressure. Cam 103 has a
number of cam lobes equal in number to the number of high pressure
outlets 112. Fuel enters the suction side of transfer pump 104
equipped with a pressure regulating valve 105 through a passage
105A from the fuel tank and filter (not shown) and is delivered
through passages 107A at suitable pressure to inlet passages 107 in
rotor 106 of distributor 106A. When inlet passages 107 in rotor 106
are closed, that is, inlet passages 107 are not in registry with
passages 107A because of the angular position of distributor 106A,
fuel from transfer pump 104 is by-passed through pressure
regulating valve 105 to the suction side of transfer pump 104.
Rotor 106 is rotated by shaft 122 and timed to the engine crank
shaft. As rotor 106 rotates inlet passages 107 register with
passages 107A and cam 103 allows plungers 102 to be displaced
radially in an outward direction by fuel entering the cylinder
between the plungers under transfer pump pressure. Of course,
springs may be employed if necessary to increase the outward force
on the plungers. As plungers 102 reach their maximum separation,
inlet passages 107 close by moving out of registry with passages
107A, and delivery passage 108 in rotor 106 registers with a
passage 124 connected to a delivery valve 112A. Simultaneously,
plungers 102 are moved radially toward one another by a cam lobe
and pressurize the fuel which is displaced through a passage 123 to
a registering high pressure delivery passage 124 and associated
delivery valve 112A. Fuel also is displaced through groove 125 into
annulus 109 in rotor 106 through passages 126 to annuli 127.
When the solenoid of either or both valves 111 are deenergized and
in open position pressurized fuel flows through the spill path to
the fuel tank. Fuel flows through the deenergized valve to the
spill path through annulus 127, through annulus 128, passages 129,
130 and 131 and annulus 132 in the valve and through annulus 133,
passage 134, annulus 110, passages 135 and 136 and through an
outlet fitting 142 to the fuel tank.
Injection of fuel into the appropriate engine cylinder occurs when
both solenoid valves are energized to their closed position to
close the spill path. Fuel under high pressure then flows through
passage 123 in rotor 106 to the registering passage 124 and
associated delivery valve 112A to the engine cylinder.
Fuel leaking from solenoid valve pistons 137 into cavities 138 is
returned to the suction side of the transfer pump through passage
139. Also, fuel leaking into cavity 140A is returned through
similar passages (not shown) to the suction side of the transfer
pump. Valves 111 are closed by energization of a solenoid 141 by
signals generated by a rotor 113 which is angularly timed to the
engine crank shaft to pass the pole of a trigger coil 117 and
induce a pulse in the trigger coil. The trigger coil is connected
by conductors 118 to terminals 115 molded in cap 119. Terminals 115
are connected to an electronic circuit (not shown) for converting
the signals to power pulses for energizing the solenoid valves.
Suitable electrical conductors (not shown) connect the electronic
circuit to terminals 115A (FIG. 6) also molded in cap 119. From
terminals 115 power pulses flow through conductors 116 and spring
terminals 114 to the grounded coils 141 of the solenoid valves 111.
Valves 111 are opened by springs 140 when coils 141 are
deenergized. With this arrangement in case of failure of the
electrical system generating the control pulses, the engine will
stop.
At the beginning of each pumping period of plungers 102 one valve
111 is closed and the other valve is open so that fuel is displaced
through the open valve to the spill path. Injection begins by
energizing the open valve 111 to closed position. High pressure
fuel delivery to the engine continues until the first valve 111 is
deenergized and opens to permit fuel to flow to the spill path.
The timing arrangement for a four cylinder pump shown in FIGS. 5 to
7 is shown in FIG. 8. The injection pulses occur every 90.degree.
of cam rotation and each valve opens or closes every 45.degree..
The injection period .theta..sub.m is varied by changing the
angular overlap in which both valves 101 and 102 are closed to vary
the quantity of fuel delivered to the engine cylinders. If
injection advance or retardation is desired, .theta..sub.t is
varied by advancing or retarding the events of both valves 111
simultaneously with respect to a fixed point in the engine
cycle.
A fuel injection pump constructed according to the invention avoids
the use of extremely fast acting valves and requires the use of
only two valves regardless of the number of cylinders in the
engine.
* * * * *