WO1981000283A1

WO1981000283A1 - Electrically controlled fuel injection apparatus

Info

Publication number: WO1981000283A1
Application number: PCT/US1979/000506
Authority: WO
Inventors: S Kranc
Original assignee: Caterpillar Tractor Co
Current assignee: Caterpillar Inc
Priority date: 1979-07-16
Filing date: 1979-07-16
Publication date: 1981-02-05
Anticipated expiration: 1982-01-16

Abstract

A solenoid has been used to reciprocably move a single spool valve for controlling timing and duration of fuel injection. This is undesirable due to resulting high inertial loads and high energy requirements for opening the single valve. Apparatus (10) is provided having first and second reciprocably movable valves (72, 92). The first valve (72) is movable only for beginning injection and the second valve (92) is movable only for ending injection. The valves (72, 92) are actuated by separate solenoids (80, 101) and may be returned by a spring (88, 108).

Description

Electrically Controlled Fuel Injection Apparatus

Technical Field

This invention relates generally to internal combustion engines and more particularly to those having electrically controlled fuel injection.

Background Art

Electrical control of fuel injection is versa¬ tile and thus advantageous. In general, it allows accomplishment of several important objectives such as excellent control of exhaust emissions; improved engine response; programming of desired torque characteristics of the engine; programming of desired speed regulations; provision for rapid shutdown of engines; and improved fuel economy.

Controlling the amount of fuel injected into an engine has been accomplished by a single linearly acting or reciprocating solenoid controlled valve. The single valve has to move in one direction to start in- jection and in the other direction to stop injection. However, this requires relatively large amounts of electrical energy to start and stop the reciprocating mass. Further, the rapidly reciprocating mass which starts and stops several times per second produces relatively large inertial forces which can cause an undesirable vibration or bounce.

In view of the above, it would be advantageous to provide an electrically controlled fuel injection apparatus for controlling the amount of fuel injected into an engine which overcomes the problems associated with the prior art. -2-

Disclosure of Invention

In one aspect of the present invention, the problems pertaining to the known prior art, as set forth above, are advantageously avoided. This is accomplished by providing an electri¬ cally controlled fuel injection apparatus including a fuel supply conduit and a fuel return conduit. A first valve controls fuel supply through the supply conduit by reciprocating in the supply conduit between first and second positions. A second valve controls fuel return through the return conduit by reciprocating in the return conduit between first and second positions.

The foregoing and other advantages will become apparent from the following detailed description of the invention when considered in conjunction with the accom¬ panying drawing. It is to be expressly understood, however, that the drawing is not intended as a defini¬ tion of the invention but is for the purpose of illus¬ tration only.

Brief Description of the Drawing

In the drawing:

The Figure is a view illustrating the apparatus of this invention.

Best Mode for Carrying Out the Invention in the Figure, a unit fuel injection apparatus is designated 10 and includes a unit fuel injector pump 12 operatively connected to a known fuel supply tank 14 from which fuel is transferred to the fuel injector pump 12 by a known fuel transfer pump 16, preferably through a filter 18. The fuel is supplied to a housing 24 through a conduit 17. Fuel enters housing 24 at port 56 of fuel supply conduit 20. Fuel exits from a fuel return conduit 22 in housing 24 at a port 62 and is conducted back to tank 14 through a conduit 19. Unit fuel injection pump 12 includes housing 24 having a tappet 28 resiliently biased by spring 30 and driven by a lobe 32 on a camshaft 34 as is well known. As a result, a plunger 36 is a means for re- ciprocating in a first bore 38 within housing 24. Fuel, delivered to first bore 38, is injected into an engine cylinder (not shown) via an injection passage 40 and injection ports 42 in a tip assembly 44. This well known arrangement functions due to differential areas on a fuel injection valve 46 biased by a spring 48 in tip assembly 44.

The fuel is expelled through ports 42 due to its substantial pressurization periodically occurring within first bore 38 as plunger 36 continuously recip- rocates. Controlling the quantity and timing of the injection of fuel through ports 42 is the subject of much technology due to present trends in enhancing fuel economy and fuel emissions. Such technology is complicated because the control of quantity and timing must be coordinated with other engine functions and conditions. Since the lobe- 32 and plunger 36 have a fixed cyclical relationship for pressurizing the fuel in first bore 38, variations in controlling quantity and timing of injection usually involve electrical and/or mechanical control of the admittance of fuel to first bore 38.

Plunger 36 includes an annular relief 50 formed therein and an end 52. A second bore 54, formed in plunger 36, fluidly interconnects end 52 adjacent cavity 100 and relief 50. As illustrated, plunger 36 reciprocates between a dotted line position "A" and a solid line position "B".

Fuel supply conduit 20 extends into housing 24 from port 56 and merges with fuel return conduit 22 to form fuel conduit 26. Fuel conduit 26 terminates at bore 38 adjacent relief 50. In this manner, supply conduit 20 and return conduit 22 are fluidly connected to relief 50 of plunger 36 in first bore 38. Plunger 36 is of a construction sufficient for maintaining relief 50 in continuous fluid connection with fuel con¬ duit 26 in response to plunger 36 being reciprocated between positions "A" and "B".

Fuel supply conduit 20 includes an enlarged bore 70 transversely disposed therein. Bore 70 accom- modates a spool valve 72, which functions as a means for beginning injection, and is mounted in bore 70 in a first (solid line) position "C" wherein end 74 of valve 72 seats against a shoulder 76. In first position "C", a reduced diameter portion 78 of valve 72 opens supply conduit 20. Electrical means, such as a solenoid 80, is connected to be energized to actuate valve 72 to move in one direction, as illustrated by an arrow designated 82, from first position "C" to a second (dotted line) position "D" wherein an enlarged diameter portion 84 of valve 72 closes supply conduit 20 at a port 86. When solenoid 80 is deenergized, valve 72 is urged by a resilient means, such as a compression spring 88, from second position "D" back to first position "C", seated against shoulder 76 opening conduit 20. Thus, valve 72 functions as a means for controlling fuel supply through supply conduit 20.

Fuel return conduit 22 also includes an en¬ larged bore 90 transversely disposed therewith. Bore 90 accommodates a spool valve 92, which functions as a means for ending injection, and is mounted in bore 90 in a first (solid line) position "E" wherein end 94 of valve 92 seats against a shoulder 96. In first position "E", an enlarged diameter portion 98 of valve 92 closes return conduit 22 at a port 106. Electrical

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eans, such as a solenoid 101, is connected to be energized to actuate valve 92 to move in one direction, as illustrated by an arrow designated 102, from the first position "E" to a second (dotted line) position "F" wherein a reduced diameter portion 104 of valve 92 opens return conduit 22 at port 106. When solenoid 101 is deenergized, valve 92 is urged by a resilient means such as a compression spring 108, from second position "F" back to first position "E", seated against shoulder 96 closing conduit 22. Thus, valve 92 functions as a means for controlling fuel return through return conduit 22.

Electrical means are employed to determine the start of injection as well as to determine the quantity of fuel injected. Such means are well known and are not the subject of this invention. These means usually include a power source, sensing devices, actuators, and the like. Such means take into account inlet manifold pressure and temperature, engine speed and load, and even fuel temperature. A brief enabling discussion of the parameters of such means is considered below.

Valves 72,92 are driven in a single linear motion by electrical means such as suitable solenoids 80,101. Valves 72,92 are also urged backwards in a single linear motion, opposite the solenoid motion. Considerations to be made in selecting solenoids 80,101 include a high response device, that is, a device which has rapid response so as to avoid a detrimental lag between the time a signal is received and valves 72,92 are actuated. Also, the loads on valves 72,92 must be considered within the parameters of the pressurized fuel system associated with fuel injection. Another consideration is the amount of travel required or the distance through which valves 72,92 are to be moved between positions "C","D" and "E","F" , respectively. A well known logic system, the universal fuel injection system, UFIS, developed for the military for use in track type or armored vehicles, is available for actuating a fuel pump control system. The UFIS reads and interprets vehicle data such as engine speed, boost or manifold pressure, engine temperature, ambient tem¬ perature, altitude, load, etc. The UFIS is powered by the vehicular power system, e.g., a twelve (12) or twenty-four (24) volt system or the like. The UFIS logic requires relatively low milliamperage. Solenoids 80,101, however, require relatively high amperage due to the rapid response needs. Thus, signals from the UFIS which tell solenoids 80,101 when to actuate valves 72,92 in response to constantly changing engine needs, must be modified. Where solenoids 80,101 are used, a power amplifier is needed to boost the UFIS signal and relay it to solenoids 80,101.

Industrial Applicability

With the parts assembled as set forth above, transfer pump 16 maintains a system pressure at about 30-35 psi. Valve 72 is in first position "C", opening supply conduit 20 to supply fuel to cavity 100 in housing 24. Valve 92 is in first position "E", closing return conduit 22 from returning f el to tank 14. Cam 34 and lobe 32 rotate and cause plunger 36 to recipro¬ cate between positions "A" and "B" permitting relief 50 to maintain fluid communication with supply conduit 20. A signal from the UFIS energizes solenoid 80 to move valve 82 to second position "D" thus closing supply conduit 20 at port 86. This occurs when plunger 36 is moving from position "A" toward position "B" thus decreasing the volume of cavity 100 and increasing the pressure of fuel therein. Valve 92 is in position "E" and thus fuel in cavity 100 is pressurized sufficiently to begin injection at ports 42. -7-

Al ost instantaneously, that is, within milli¬ seconds of the beginning of injection, as plunger is still moving toward position "B", a signal energizes solenoid 101 to move valve 102 to second position "F", thus opening return conduit 22 at port 106. Pressure is relieved and injection stops. Solenoids 80,101 are deenergized and both valves 82,102 are returned to their respective first positions "C","E". Due to use of springs 88,108, the need for additional energy and rapid movement of valves 82,102 is avoided. Since two valves are used, one for beginning and one for ending injection, there is no need to rapidly reciprocate a single valve in alternating directions.

The foregoing has described an electrically controlled fuel injection apparatus' including a first means for beginning injection and a second, separate, means for ending injection.

Other aspects, objects and advantages of this invention can be obtained from a study of the drawing, the disclosure and the_. appended claims.

Claims

-8-Claims

1. An electrically controlled fuel injection apparatus (10) comprising: a fuel supply conduit (20) connected to said apparatus (10) ; a fuel return conduit (22) connected to said apparatus (10) ; first means for starting injection, said means being a first valve (72) electrically actuated for movement in said supply conduit (20) from a first (C) to a second (D) position? and second means for stopping injection, said means being a second valve (92) electrically actuated for movement in said return conduit from a first (E) to a second (F) position.

2. The apparatus (10) of claim 1 wherein said first valve (72) in said first position (C) opens said supply conduit (20) .

3. The apparatus (10) of claim_.2 wherein said first valve (72) in said second position (D) closes said supply conduit (20) .

4. The apparatus (10) of claim 3, including: first electrical means connected for moving said first valve from said first to said second positions, said means being a solenoid (80).

5. The apparatus (10) of claim 4, including: first resilient means (88) connected for moving said first valve (72) from said second (D) to said first (C) positions. -9-

6. The apparatus (10) of claim 5 wherein said second valve (92) in said first position (E) , closes said return conduit (22) .

7. The apparatus (10) of claim 6 wherein said second valve (92) in said second position (F) , opens said return conduit (22) .

8. The apparatus (10) of claim 7, including: second electrical means connected for moving said second valve from said first to said second positions, said means being a solenoid (101) .

9. The apparatus (10) of claim 8, including: second resilient means (108) connected for moving said second valve (92) from said second (F) to said first (E) positions.

10. The apparatus (10) of claim 1, including: first electrical means (80) connected for moving said first valve (72) from a first position (C) wherein said supply conduit (20) is open, to a second position (D) wherein said supply conduit (20) is closed; and second electrical means (101) connected for moving said second valve (92) from a first position (E) wherein said return conduit (22) is closed, to a second position (F) wherein said return conduit (22) is open.

11. The apparatus (10) of claim 10 wherein said first and second electrical means are solenoids (80,101) .

12. The apparatus (10) of claim 11, including: first resilient means (88) connected for mov¬ ing said first valve (72) to said first position (C) ; and second resilient means (108) connected for moving said second valve (92) to said first position (E) .

13. The apparatus (10) of claim 1 wherein: said first valve (72) , in said first position (c) , opens said supply conduit (20) ; said first valve (72) , in said second position (D) , closes said supply conduit(20) ; said second valve (92) , in said first position (E) , closes said return conduit (22) ; and said second valve (92) , in said second position (F) , opens said return conduit (22) .

14. The apparatus (10) of claim 13, in¬ cluding: first electrical means (80) connected for moving said first valve (72) from said first (C) to said second (D) position; and second electrical means (101) connected for moving said second valve (92) from said first (E) to said second (F) position.

15. T e apparatus (10) of claim 14, including: first resilient means (88) for moving said first valve (72) from said second (D) to said first (C) position; and second resilient means (108) for moving said second valve (92) from said second (F) to said first (E) position.

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16. The apparatus (10) of claim 1, including: first electrical means (80) for moving said first valve (72) from one of said first (C) and second (D) positions to the other of said first (C) and second (D) positions; and second electrical means (101) for moving said second valve (92) from one of said first (E) and second (F) positions to the other of said first (E) and second (F) positions.

17. The apparatus (10) of claim 16, including: resilient means (88,108) for moving said first (72) and second (92) valves from one of said first (C,E) and second (D,F) positions to the other of said first (C,E) and second (D,F) positions.

18. An electrically controlled fuel injection apparatus (10) comprising: a unit fuel injector; a fuel supply conduit (20) connected to said injector; a fuel return conduit (22) connected to said injector; first means (80) for controlling fuel supply through said supply conduit (20) , said means (80) being a first valve (72) connected to be electrically act- uated for movement from a first normally open position (C) to a second closed position (D) ; and second means (101) for controlling fuel return through said return conduit (22) , said means (101) being a second valve (92) connected to be electrically actuated for movement from a first (E) normally closed position to a second (F) open position.

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19. The apparatus (10) of claim 18, in¬ cluding: first resilient means (88) for moving said first valve (72) from said second (D) to said first (C) position; and second resilient means (108) for moving said second valve (92) from said second (F) to said first (E) position.

20. An electrically controlled fuel injeσ- tion apparatus (10) comprising: a unit fuel injector (12) ; a fuel supply conduit (20) connected to said injector; a fuel return conduit (22) connected to said injector; first means for beginning injection, said means being a first spool valve (72) reciprocably mounted in said supply conduit (20) and having a first electrical means (80) connected for moving said first valve (72) from a first position (C) wherein said supply conduit (20) is normally open, to a second position (D) wherein said supply conduit (20) is closed; and second means for ending injection, said means being a second spool valve (92) reciprocably mounted in said return conduit (22) and having a second electrical means (101) connected for moving said second valve (92) from a first position (E) wherein said return conduit (22) is normally closed, to a second position (F) wherein said return conduit (22) is open.

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