US3409226A

US3409226A - Fuel injection apparatus for piston-type internal combustion engines

Info

Publication number: US3409226A
Application number: US547876A
Authority: US
Inventors: Steiger Anton
Original assignee: Sulzer AG
Current assignee: Sulzer AG
Priority date: 1965-06-11
Filing date: 1966-05-05
Publication date: 1968-11-05
Anticipated expiration: 1985-11-05
Also published as: CH438841A; GB1111515A; NL6508963A; NL128320C; ES327715A1

Description

Nov. 5, 1968 A. STEIGER FUEL INJECTION APPARATUS FOR PISTON-TYPE INTERNAL COMBUSTION ENGINES Filed May 5. 1966 Inventor: ANTON STEIGER ATTORNEYS United States Patent 3,409,226 FUEL INJECTION APPARATUS FOR PISTON-TYPE INTERNAL COMBUSTION ENGINES Anton Steiger, Zurich, Switzerland, assignor to Sulzer Brothers Limited, Winterthur, Switzerland, a Swiss company Filed May 5, 1966, Ser. No. 547,876 Claims priority, application Switzerland, June 11, 1965, 8,163/ 65 1 Claim. (Cl. 23994) ABSTRACT OF THE DISCLOSURE There is disclosed a fuel injection device for diesel engines in which a fuel pump delivers fuel at high pressure into a first storage chamber and also, for large pump strokes, into a second storage chamber communicating with the first through a valve which opens for pressure in the first chamber above a threshold value attained only on pump strokes greater than those corresponding to an idling setting of the engine. The valve is biased toward closing position by a spring which sets the threshold and which also bears against a piston exposed at its other end to the pressure in a control chamber. This piston in turn bears, through an extension passing through the control chamber, against a valve stem controlling the injection orifice between the engine cylinder and a nozzle chamber which is connected to the first storage chamber. The control chamber is connected through a timing device successively to the pump discharge and to a low pressure pump return line. When the control chamber is connected to the pump discharge, the valve stem is held on its seat to prevent passage of fuel from the nozzle chamber into the engine cylinder, and at the same time the piston compresses the spring, providing a clearance between the extension and piston. When the control chamber is connected to the return line, the pressure in the control chamber falls and the valve stem is lifted off its seat by the pressure in the nozzle chamber, as allowed by the clearance just mentioned. This permits injection of fuel from the nozzle chamber into the engine cylinder until the valve stem is returnel to its seat by action of the piston under influence of the spring.

The present invention pertains to a fuel injection device for piston-type internal combustion engines in which there is provided for each cylinder of the engine a separate store of fuel supplied from a fuel pump to an injection valve. According to the present invention the injection valve includes at least two chambers for storage of such fuel, one of those chambers being directly connected to the high pressure fuel line arriving from the fuel pump and the other being connected to that line via a valve which opens to admit fuel into that other chamher only when the pressure in the high pressure fuel line exceeds a certain threshold or minimum value.

In the prior art fuel injection devices having means for storage of fuel of which I am aware, such as for example that shown in German Patent No. 512,368, there have been provided at most a single accumulator or storage chamber per injection valve. In such prior art systems fuel is delivered during a storage phase from the pump into the storage chamber and into the conduits pertaining thereto. The consequence is a rise in pressure in the storage chamber, the amount of this rise being dependent on the volume of that chamber, on the elasticity of the system, and on the quantity of fuel pumped. The volume of the storage chamber has in these prior art devices been so chosen that at the highest pumping rate encountered, i.e., for the maximum volume of fuel delivered per pump cycle, which determines the maximum volume of fuel to be injected by the injector per injector cycle, the pressure built up in the storage chamber does not exceed a specified limiting value. A storage chamber so dimensioned however usually undergoes only a small increase in pressure during pumping when the pump delivers only a small quantity of fuel per pump cycle, i.e., when the engine operates at low injection rates, as for example upon idling. The volume of fuel supplied to and withdrawn from the storage chamber is in such circumstances small compared to the total volume of the chamber. The result is inexactitude in the metering of small quantities of fuel and it may, for example, produce uneven idling of the engine.

In accordance with the invention there is provided a fuel injection system which surmounts these disadvantages and in which the metering of small as well as large fuel charges can be effected with high accuracy.

The invention will now be further described in terms of a nonlimitative example with reference to the accompanying drawings wherein:

FIG. 1 is a diagram of one embodiment of the invention, the showing being partly in section; and

FIG. 2 is a sectional view taken on the line IIII in FIG. 1.

The fuel injection system of the invention shown in the drawings includes a fuel pump 1, which may be of normal construction, and which is driven from a cam shaft 2 by a cam 3. The pump draws fuel from a supply line 4 and delivers it to a high pressure line 5. The rate at which fuel is pumped, i.e., the quantity of fuel delivered by the pump per pump cycle, can be adjusted in known fashion by adjustment of a toothed rack 6. The high pressure line 5 leads toan injection valve generally indicated at 7 which is disposed in the cylinder head 8 of a diesel engine. One such injection valve may be provided for each cylinder of the engine. Upstream of the injection valve a control line 10 is connected into the high pressure line 5, the line 10 leading to an injection control device 11.

The injection valve 7 includes a seat containing portion 12 and a housing 13. Injection openings are formed in the seat 12 and can be closed off from the fuel supply at bore 23 by means of a movable valve stem or needle 14. More particularly, a reduced lower portion 14' at the lower end of stem 14 has a conical tip which by lowering or raising of stem 14 can be applied against or withdrawn from a conical seat formed in seat member 12 between a nozzle space 24 at the lower end of bore 23 and a central channel 15 which leads to the injection openings 15. In the bore 16 above the valve stem 14, there is disposed a valve motion control piston 17 of somewhat larger diameter than the valve stem 14. The valve stem 14 is provided at the upper end thereof with an extension 18 of reduced diameter against the upper end of which the piston 17 can bear. A valve actuating or control chamber 20 is defined between the extension 18 and the walls of the bore 16. The valve actuating chamber 20 is connected via bores 21 in the

seat

12 and 22 in housing 13 to the control line 10' which constitutes an extension of line 10 downstream of the injection control device 11. The bore 23 connects the nozzle chamber 24 in the seat 12 with a bore 25 in the housing 13, the bore 25 in turn connecting via a bore 26 with the high pressure fuel line 5.

The bore 26 leads in injector 7 to a first accumulator or storage chamber 27. A vertical bore 28 leads from the chamber 27 vertically downwards and a horizontal bore 30 connects the bore 28 into a second storage chamber 31 of somewhat larger volume than the chamber 27. The bore 28 is provided with a conical valve seat and can be closed by means of a cylindrical valve body 32 upon upward motion thereof, the body 32 having a corresponding conical surface for mating with the conical valve seat just mentioned. The valve body 32 bears at its lower end against a disk 33 fitted into the upper end of a spring 34, the lower end of the spring containing a corresponding disk 35 which bears against the upper end of piston 17. The motions of the

disks

33 and 35 are limited by shoulders on an abutment cylinder 36.

The fuel control device 11, shown in axial section in FIG. 2, is shown constructed for metering of fuel to the four cylinders of a four-cylinder engine. All necessary flow channels are accordingly provided four-fold, at angular positions corresponding to the firing order of the four cylinders. The control device 11 includes a rotating cylindrical distributor 40 which controls operation of the four injection valves of the four cylinders in succession. Distributor 40 is driven by

gears

41 and 42 from a control shaft 43. The drive is so established that the cylinder 40 rotates, in a two-stroke cycle engine, with half the angular speed of the engine crank shaft, and the control device effects for each revolution of distributor 40 two injections into each cylinder of the engine. The cylinder 40 is supported coaxially within the cylindrical phasing sleeve 44 which can be shifted angularly by means of a lever extension 44 thereon so as to advance or retard the injection times by reference to, e.g., top dead center in the cylinders of the engine. Fuel is introduced into the distributor 40 from line 10 through channels 45 of a housing 39 of device 11 within which the sleeve and distributor are supported, and the fuel leaves the distributor 40 through further channels 46 which connect to the line 10'. For each cylinder of the engine there is provided one set of

channels

45 and 46. To permit adjustable interconnection of the inlet channels 45 of the injection control device 11 with the outlet channels 46 thereof the sleeve 44 is provided with slits 47 and the cylinder 40 with cutouts 48. The cylinder 40 also includes a central bore 50 which is continuously connected through

bores

51 and 52 to a fuel return line 49. Bores 53 lead from the central bore 50 outwardly to the slits 47 of the sleeve 44. The construction is such that, according to the relative position of the distributor 40 and the sleeve 44 and for each cylinder of the engine, either the line 10 is connected through the

channels

45 and 46 to the line 10', or else the line 10 and hence the valve motion control chamber 20 are connected to the return line 49 and are therefore practically free from pressure. Each revolution of distributor 40 takes each cylinder of the engine, and more particularly the injector 7 thereof, through two cycles, each including a phase in which

lines

10 and 10 of that cylinder are interconnected and a phase in which line 10' of that cylinder is connected to line 49.

Prior to each injection the pump 1 executes three delivery strokes by action of the cam 3. The line and, through bore 26, the chamber 27 are thereby subjected to pressure, and the chamber 31 may also be subjected to pressure, depending on the quantity of fuel delivered by the pump and the consequent action of valve 32, to be presently explained. The quantity of fuel delivered by the pump and the quantity of fuel consequently stored in chamber 27 or in

chambers

27 and 31 are controlled by operation on the pump of metering control element 6. correspondingly at the end of the last of the three delivery strokes there is established in the injection system a pressure dependent upon the quantity of fuel to be injected.

Since during the storage phase the lines and 10' are connected together through the control device 11, this pressure is also exerted in the valve actuating chamber of the injection valve. Hence piston 17 is lifted clear of valve stem extension 18, compressing spring 34 until disk brings up against the lower stop shoulder of cylinder 36. In this way the valve stem 14 is freed from the influence of the spring 34. Since the valve stem rests on its seat at the lower end of the nozzle chamber 24 the pressure in chamber 24 is ineffective over most of all of the conical area at the lower end of the lower extension 14 of valve stem 14, and the downward force exerted on stem 14 by the pressure in chamber 20 therefore outweighs the upward force exerted on the valve stem in the nozzle chamber 24. The valve stem 14 is therefore stressed downwardly against its seat by the difference between these two forces and prevents the passage of fuel from chamber 24 to the nozzles 15. Account is taken in the dimensioning of the parts for the upward force exerted on stem 14 by gas pressure existing in the engine cylinder so that chamber 24 remains closed from

passages

15 and 15 even after piston 17 is lifted, until the pressure in chamber 20 is relieved as will now be explained.

The moment of fuel injection is controlled by the control device 11. When with the steady rotation of cylinder 40 the connection between lines 10 and 10' is broken, the line 10' and hence chamber 20 are connected with the return line 49. Consequently, the pressure in the control chamber 20 suddenly declines. The pressure exerted from chamber 24 on the valve stem will then prevail; the valve stem will be lifted, and the injection process proper will begin. The end of injection is specified by the strength of the spring 34. As soon as the force exerted thereby outweighs that produced by the pressure in chamber 24, the stem 14 will be returned to its seat and injection will terminate.

During the storage process, i.e., the pumping strokes of pump 1, the fuel is first delivered to the smaller chamber 27. When, as occurs upon pumping of large fuel charges as set at control 6, the pressure produced by the pump in chamber 27 rises above a limit specified by the cross-section of the valve 32 and the strength of the spring 34, the valve body 32 will move downwardly, opening a passage at line 30 to the chamber 31. The further fuel delivered by the pump during the remainder of the threestroke pumping operation then produces a further rise in pressure in both of the

chambers

27 and 31. Conversely, upon the immediately following injection the stored fuel is first withdrawn from the two storage spaces 27 and 31 (via

bores

30, 26, 25 and 23 leading to chamber 24) until the pressure in the injection system declines to a level at which the valve body 32 rises and cuts off connection to the chamber 31. The remainder of the injection consequently involves only fuel from the smaller chamber 27. When in operation at partial or light load the quantity of fuel delivered from the pump 1 is so small that the pressure generated thereby is insuificient to lift the valve body 32, the injection valve of the invention operates through action of the chamber 27 only.

By means of the arrangement of the invention, including two storage chambers, it is possible to design these separately for the requirements of partial load and full load operation of the engine. In this way it is possible to achieve a more exact metering of small quantities of fuel, these small quantities of fuel producing larger pressure rises in the small volume of the first storage chamber which alone is involved upon such operation. These pressure rises in particular are larger than those which would be achieved at such light load operation were there provided only a single storage chamber having the volume of the two separate storage chambers of the invention. Furthermore, on full load the pressure rise in the two storage chambers is smaller than that which would be achieved with the corresponding injected quantity if only one storage chamber were provided having the volume of the chamber 27. This is especially true if the volume of the second storage chamber is larger than that of the first. With the construction of the invention employing two storage chambers, it is possible to achieve an especially good match of the storage characteristics even with very wide differences between maximum and minimum fuel charges.

The invention can of course be embodied in apparatus employing more than two storage chambers, each thereof beyond the first being provided with a separate valve such as the valve 32, these valves opening at successively higher pressures. Thus for pressures developed by the pump up to an initial minimum pressure, only one storage chamber is operative. Thereafter for pressures up to a second limit two chambers are employed whereas for pressures above this second limit and below a third limit three chambers are employed, and so on. It is desirable though not necessary that the chambers thus successively employed in the injection process be of successively increasing volume.

The fuel injection valve for piston-type internal combustion engines of the invention thus comprises a seat having an aperture therein. In the embodiment disclosed this seat takes the form of the member 12, and the aperture is defined by the

passages

15 and 15 therein, which via chamber 24 and

passages

23, 25 and 26 give access between the interior of the engine cylinder on the one hand and the exterior thereto on the other hand. The valve further comprises a valve stem 14 retractably engageable with the seat at that aperture to close it. The valve further comprises a first fuel storage chamber 27 which communicates via

passages

26, 25 and 23 and via chamber 24 with one side of the seat at that aperture, namely the side remote from the interior of the engine cylinder into which lead the nozzle passages 15. The valve additionally comprises at least a second fuel storage chamber, as shown at 31, a conduit (shown at 30) which either directly or indirectly interconnects the first and second chambers, and means such as the valve 32 to close that conduit for pressures in the first chamber below a minimum or threshold value.

Advantageously the valve of the invention further includes resilient means such as spring 34 to stress the valve stem against its seat, means such as the chamber 20 to apply hydraulic pressure between the resilient means and the valve stem so as to disengage the two while hydraulically stressing the valve stem against its seat, and a movable piston as shown at 17 having a diameter at least as large as that of the valve stem, this piston serving to transmit the stress of the spring to the valve stem when the two are engaged and to transmit the hydraulic pressure to the spring when the spring and valve stem are disengaged. Moreover, in the preferred embodiment which has been illustrated, the resilient means so retractably engagea-ble with the valve stem also bears against the valve 32, thus functioning additionally as part of the means to close the conduit between the first and second chambers fOIi pressures in the first chamber below the threshold va ue.

While the invention has been described hereinabove in terms of a presently preferred embodiment, it is not limited thereto. Thus, the invention can be embodied in other types of injection valves than that hereinabove described. With that which has been described however, the invention provides a particularly advantageous and compact construction for a storage type of injection valve which has the advantage of not requiring high power springs. In particular, employment according to the invention of the spring which engages the valve motion control piston 17 simultaneously as the spring for the valve 32 in the line interconnecting the first and second fuel storage chambers produces an additional simplification of construction by minimizing the number of parts required.

Further, other types of pressure-responsive closure devices may be employed between the first and second fuel storage chambers. More generally, the invention comprehends all modifications of and departures from the embodiment hereinabove described which properly fall within the spirit and scope of the appended claim.

I claim:

1. A fuel injection valve for a piston-type internal combustion engine, said valve comprising a seat having an aperture therein, a valve stem retractably engageable with said seat at said aperture to close said aperture, a first fuel storage chamber communicating with one side of said seat at said aperture, a second fuel storage chamber, conduit means interconnecting said chambers, means to close said conduit means in response to for pressures in said first chamber below a threshold pressure, resilient means stressing said valve stem again said seat and simultaneously bearing against and stressing said conduit-closing means in conduit closing direction, a movable piston disposed between said resilient means and valve stem, and means to apply hydraulic pressure between said piston and valve stem to disengage said piston from said valve stem and to stress said valve stem against said seat.

References Cited UNITED STATES PATENTS 1,890,702 12/1932 Steiner 23996 X 1,967,987 7/1934 Broege 23996 X 2,536,542 1/1951 Evans et a1. 239-533 X 2,556,369 6/1951 Hogeman 23996 2,788,246 4/1957 Nichols 239-96 3,131,866 5/1964 Cummins et a1. 239-533 X FOREIGN PATENTS 163,396 3/1958 Sweden.

M. HENSON WOOD, JR., Primary Examiner.

V. C. WILKS, Assistant Examiner.

Washington, D.C. 20231 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent'No. 3,409,226 November 5, 1968 Anton Steiger It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column '1, line 20, "of" should read for Column 6, line 27,

cancel "for"; line 29, "again should read against Signed and sealed this 3rd day of March 1970.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer I'U I'ILIVIII: