US3859972A - Fuel injection system for an internal combustion engine - Google Patents

Abstract

Fuel injection apparatus for an internal combustion engine having a reciprocating piston pressure pump in which separate electro-mechanical control valves are operated to begin and end each fuel injection period in timed relation to rotation of the cam shaft or crank shaft of the internal combustion engine to avoid the need of fast acting magnetic valves.

Description

United States Patent 9] Watson et al.

[ Jan. 14, 1975 FUEL INJECTION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE [75] Inventors: Edwin Ben Watson, Sidney, N.Y.; Harlan 1. Fuller, Doylestown, Pa.

[73] Assignee: The Bendix Corporation, Southfield,

Mich.

[22] Filed: June 28, 1973 [21] Appl. No.: 374,733

[52] US. Cl....123/139 AR, 123/139 E, 123/139 AD, 123/139 AE, 123/32 EA [51] Int. Cl. F02m 41/12 [58] Field of Search.... 123/104, 103, 140 R, 139 R,

123/139 AA, 139 AB, 139 AD, 139 AE,139

E, 139 AR [56] References Cited UNITED STATES PATENTS 1,664,610 4/1928 French 123/32 EA ll I2 HllllHl 3,661,130 5/1972 Eheim 123/139 E 3,724,436 4/1973 Nagata et al..... 123/139 E 3,779,225 12/1973 Watson et a]. 123/139 E Primary Examiner-Wendell E. Burns Assistant Examiner-D. Reynolds Attorney, Agent, or FirmRaymond J. Eifler [57] ABSTRACT Fuel injection apparatus for an internal combustion engine having a reciprocating piston pressure pump in which separate electro-mechanical control valves are operated to begin and end each fuel injection period in timed relation to rotation of the cam shaft or crank shaft of the internal combustion engine to avoid the need of fast acting magnetic valves.

6 Claims, 9 Drawing Figures PATENTED JAN 1 41975 sum 1 or 5 m GI uh aaowmd smast a or s PATENTED JAN 1 4' PATENTEU JAN 1 4 I975 SHEET h 0F 5 N. OE

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SHEET 5 BF 5 FUEL INJECTION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE 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-magnetically operated fuel injection valves.

The present invention has all the advantages of copending application Ser. No. 260,882 now US. Pat. No. 3,779,225, and, in addition, avoids the require ment 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'copending application, a single solenoid operated control valve controls the injection period. In the present application, separate electro-magnetic 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. Although one valve starts the injection period and the other valve ends the injection period, two valves may be used to control fuel injection from two pumps to two cylinders in the internal combustion engine so that the same number of valves and pumps is required as in the copending application referred to above. The valves operate twice each cycle at 180 intervals irrespective of the number of cylinders in the engine.

The invention contemplates a fuel injection system for an internal combustion engine having a pumping unit with a plurality of pumping chambers and means for pressurizing the fuel in the chambers, each chamber having an inlet port, a relief port, and an injection port, the injection port communicating with the engine dur ing an injection period when the relief port is closed, means for supplying fuel to the pumping chambers through the inlet ports, and a plurality of electromechanical valves-associated with the pumping chambers and arranged so that one valve closes the relief port in a pumping chamber at the start of an injection period and another valve opens the relief port in the pumping chamber at the end of the 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 the same number of valves as is required in a conventional fuel injection system using a single valve for starting and ending the fuel injection period.

Another object of the invention is to provide a fuel injection system in which each valve operates twice each cam shaft cycle at 180 intervals irrespective 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 one embodiment of the invention is 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 diagram showing schematically two pumping elements and associated valves constructed according to the invention,

FIG. 2 is a diagram showing operation of the valves in FIG. 1 and the lift displacement characteristics for the two cams operating the associated pumps during one rotation of the cam shaft.

FIG. 3 is a diagram showing schematically pumping elements and associated valves constructed according to the invention for controlling the injection periods ina six cylinder diesel engine,

FIG. 4 is a timing diagram showing the sequence in which the valves in FIG. 3 are operated,

FIG. 5 is a side view, partially in section of a fuel in jection pump constructed according to the invention,

FIG. 6 is a vertical section taken approximately on the line 66 of FIG. 5,

FIG. 7 is a partial vertical section taken on the line 77 of FIG. 5,

FIG. 8 is a horizontal view partially in section taken on the line 8-8 of FIG. 5, and

FIG. 9 is a partial horizontal section taken on the line 9-9 of FIG. 5.

Referring to the drawings, in FIG. 1 are shown two pumping units 01 and C-2 connected by passages D to electro-magnetic valves A and B. Each valve rotates between two positions 1 and 2. The valves control flow of fuel to the associated engine cylinders under high pressure by closing the relief or spill passages E. When valve A is in position 1 as shown in the drawing, the valve opens the spill passage to pumping unit C1 and closes the spill passage to pumping unit C-2. When valve B is in position 2 as shown in the drawing, the valve opens the spill passage to pumping unit C-2 and closes the spill passage to pumping unit C-I. When valve A is in position 2 the valve closes the spill passage to pumping unit C-1 and opens the spill passage to pumping unit C-2. When valve'B is in position 1 the valve closes the spill passage to pumping unit C-2 and opens the spill passage to pumping unit C-l. The valves are operated by electrical signals in timed sequence with the engine.

The plungers of pumping units C-1 and G2 are operated by the usual injection cams and for a two cylinder pump the cams are displaced on the cam shaft by as shown by the displacement curves in FIG. 2. When the plunger of pumping unit C-l rises on the delivery stroke as the cam shaft rotates through angle 6, valve A is in position 1 and valve B is in position 2 as shown in FIG. 1 and fuel is pumped by pumping unit C through valve A and by pumping unit C through valve B to spill passages E at low pressure. At angle 0, valve A is operated and rotates from position I to position 2 so that both valves A and B close the spill passage to pumping unit C-1 and fuel is displaced through a high pressure outlet (not shown) to the associated engine cylinder to begin the injection period.

When the cam shaft rotates further through angle 0, valve B is operated and rotates from position 2 to position 1 opening the spill passage to pumping unit C-l to terminate high pressure fuel delivery to the engine cylinder. At the end of angle 6,, valve A is again operated and rotates from position 2 to position 1 closing the spill path to pumping unit C-2 as shown in the drawing and fuel is delivered through a high pressure outlet (not shown) to the associated engine cylinder to begin the injection period. Fuel from pumping unit 02 is injected into the engine cylinder during angle 0, since both valves A and B close the spill paths to pumping unit C-2. At the end of angle 0,, valve B is operated and rotates from position 1 to position 2 and fuel from pump C spills through valve B to the spill passage to terminate high pressure fuel delivery to the engine cylinder. Valves A and B operate alternately and each valve operates at intervals of 180 rotation of the cam shaft for a two cylinder pump.

The beginning of the fuel delivery cycle at the end of angles 0, and 0,, can be varied by altering the time of closure of valve A relative to pumping units C-1 and C-2. The angular interval between operation 'of valves A and B must be variable to control the quantity of fuel delivered to the engine cylinder each injection so that the engine power output and speed can be varied.

The advantages of using separate valves for controlling the beginning and end of the injection period is readily apparent because each valve operates at intervals of 180 of cam shaft rotation, whereas if a single valve were used it would be required to open and close during angle 0, which may have a duration of 0.25 milliseconds or less making valve design difficult and complex. With the present arrangement, electrical and mechanical inertias can be anticipated by initiating the electrical control signal pulses in advance of the actual time of valve operation.

The arrangement described above'for a two cylinder pumpcan be used for engines of four, six, eight or more cylinders by increasing the number 'of. pumping units and valves to equal the number'of cylinders in the engine. In FIG. 3 a fuel injection pump is shown schematically for a six cylinder diesel engine with the usual firing order of l, 5, 3, 6, 2, 4. Pumping units C C C C C and C supply fuel under high pressure to engine cylinders 1, 6, 3, 4, 5 and 2, respectively.

The injection cams are arranged at 60 intervals to operate pumping units C1, C5, C3, C2, C6 and C4 in that order. The timing diagram in FIG. 4 shows the sequence ofoperations of valves A, B, C, D, E and F and each valve operates at 180 intervals which is 20 milliseconds for an engine operating at 3000 RPM sp that valve response is not critical. Fuel is injected in the associated cylinders during the shaded portions of the diagram during the intervals A fuel injection pump for a four cylinder engine is shown in greater detail in FIGS. to 9 and includes a pump body 18 rotatably' supporting at cam shaft 22 rotated by the engine in a conventional manner. Cam shaft 22 has four identical cam profiles 1 displaced angularly by 90 and machined at equally spaced intervals along its axis. Each cam profile reciprocates a plunger of a pumping unit in a cylinder for delivering fuel under high pressure to an associated engine cylinder. A section through a cam profile 1 is shown in FIG. 6 and two pumping units having plungers 3 and 3A reciprocating in cylinders 4 and 4A, respectively, are shown in FIG. 5. As shown in FIG. 6, plunger 3 is drivably connected to a tappet assembly 2 having a roller 19 urged by a follower spring into engagement with cam profile 1 so that roller 19 follows the cam profile. Similarly plunger 3A is reciprocated by a second cam profile (not shown) in cylinder 4A.

Fuel is supplied to cylinders 4 and 4A from a conventional external source through drilled passages 6, cavities 5 and fill ports 7 when plungers 3 and 3A are below fill ports 7.-

The fuel injection period is initiated upon operation of a spill port closing valve 32 by energization of a solenoid 17 and is terminated upon operation of a spill port opening valve 33 by deenergization of a solenoid 23. A distributor 37 mounted on pump body 18 provides electrical pulses to the solenoids in phase relationship with the cam profiles. The phase relationship can be varied automatically in accordance with engine speed by changing the initiation of the pulse to solenoid 17 with respect to the cam profile. The engine speed may be manually controlled by changing the length of the pulse to solenoid 23 thus changing the quantity of fuel delivered to the engine.

At the beginning of a cycle when plunger 3 is below port 7 and is moved upwardly by rotation of the cam profile, .the plunger displaces fuel from cylinder 4 through fill port 7 and through spill port closing valve 32 since solenoid 17 is deenergized and valve 32 is held in open position with a slot 31 in the valve in registry with a slot 8 in the body by a spring (not shown) acting against the armature of solenoid 17 which is operatively connected to port closing valve 32. Fuel at low pressure spills from cylinder 4 through passage 30, slots 8 and 31, and passages 13,14, 15 and 16 to cavity 5. Spill port opening valve 33 is closed since solenoid 23 is energized by a pulse from distributor 37. When valve 33 is in closed position a slot 24 in the valve does not register 'with a slot 12 in the body (FIG. 7).

At the beginning of the fuel injection period solenoid 17 is energized by a pulse from distributor 37 and rotates valve 32 to closed position so that slots 8 and 31 no longer register and fuel does not spill at low pressure. Fuel then flows through passage 9, delivery valve 39 and intake conventional high pressure line 40 directly into the engine cylinder through conventional injector assembly. Fuel is delivered to the engine while both valves 32 and 33 are in the closedposition, that is, when the slots 31 and 24 in valves 32 and 33 do not line up with the slots 8 and 12 in the body, respectively. The delivery period is terminated at the end of the pulse from distributor 37 to solenoid 23 whereupon the return spring (not shown) rotates spill port opening valve 33 so that slots 12 and 24 are in registry. Fuel delivery to the engine cylinder stops and fuel flows from pump cylinder 4, through passage 9, into cavity 10, through passage 1 1, slots 12 and 24 in valve 33, passage 26 annulus 27 and through passage 28 into supply chamber 5. Plunger 3 continues to move upwardly in cylinder 4 and upon reaching the top of its travel no more fuel is displaced as described abovefrom cylinder 4. This ends a complete cycle for plunger 3 and valves 32 and 33 are in the same position in relation to plunger 3A as they were at the beginning of the cycle for plunger 3. The same two valves perform the same function as described above with respect to plunger 3A.

' As plunger 3A rises in cylinder 4A fuel is displaced by the pumping action of plunger 3A and is initially spilled through valve 32 into cavity 49, passage 43 to cavity 44, passage 46, slots 47 and 48 into cavity 13 and into the supply chamber as in the previous cycle. A fuel injection cycle begins when solenoid 17 is energized by a pulse from distributor 37 to rotate valve 32 to the closed position. The fuel injection cycle is terminated at the end of the pulse energizing solenoid 23 so that valve 33 opens and fuel flows from cylinder 4, passage 51, through slots 52 and 53 to chamber 25 passing into supply chamber 5 as in the previous cycle. Similarly, a spill port closing valve and a spill port opening valve are provided for the other two pumping units for supplying fuel to the other two cylinders and the valves are operated by energization of the associated solenoids in the manner described above in connection with valves 32 and 33 and solenoids 17 and 23, respectively.

The present invention avoids the use of fast acting magnetic valves since the valves operate twice each cycle at 180 intervals irrespective of the number of cylinders in the engine. Also the same number of valves is used as in a conventional fuel injection system where a single valve is used for both starting and ending the fuel injection period.

As in the above mentioned copending application, the valves in opening or closing do not have to oppose the pressure in the pressure chamber and require relatively small electromechanical energy.

What is claimed is:

l. A fuel injection system for an internal combustion engine having a pumping unit with a plurality of pumping chambers, each chamber having an inlet port, a relief port, and an injection port, the injection port communicating with the engine during an injection period when the relief port is closed, means for supplying fuel to the pumping chambers through the inlet ports, means for pressurizing the fuel in the chambers, and a plurality of electromechanical valves associated with the pumping chambers, and means for providing electrical signals in timed relation to the engine for controlling one valve to close the relief port in a pumping chamber to start an injection period and for controlling another valve to open the relief port in the pumping chamber to end the injection period.

2. A fuel injection system as described in claim 1 in which the number of pumping chambers and the number of valves is equal to the number of cylinders in the internal combustion engine.

3. A fuel injection system as described in claim 1 in which one valve opens the relief ports in two associated pumping chambers and another valve closes the relief ports in the two pumping chambers.

4. A fuel injection system as described in claim 1 in which each valve operates at intervals of 5. A fuel injection system as described in claim 1 in which the means for pressurizing the fuel in the chambers are reciprocating pistons which periodically pressurize the fuel in the chambers 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 distributor operated by a cam shaft in the pumping unit.

Claims (6)

1. A fuel injection system for an internal combustion engine having a pumping unit with a plurality of pumping chambers, each chamber having an inlet port, a relief port, and an injection port, the injection port communicating with the engine during an injection period when the relief port is closed, means for supplying fuel to the pumping chambers through the inlet ports, means for pressurizing the fuel in the chambers, and a plurality of electromechanical valves associated with the pumping chambers, and means for providing electrical signals in timed relation to the engine for controlling one valve to close the relief port in a pumping chamber to start an injection period and for controlling another valve to open the relief port in the pumping chamber to end the injection period.

2. A fuel injection system as described in claim 1 in which the number of pumping chambers and the number of valves is equal to the number of cylinders in the internal combustion engine.

3. A fuel injection system as described in claim 1 in which one valve opens the relief ports in two associated pumping chambers and another valve closes the relief ports in the two pumping chambers.

4. A fuel injection system as described in claim 1 in which each valve operates at intervals of 180*.

5. A fuel injection system as described in claim 1 in which the means for pressurizing the fuel in the chambers are reciprocating pistons which periodically pressurize the fuel in the chambers 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 distributor operated by a cam shaft in the pumping unit.

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