US2380148A - Fuel injecting means for internalcombustion engines - Google Patents

Description

- July 10, 1945. H CAMNER 2,380,148

FUEL INJEGTING MEANS FOR I NTERNALCOMBUSTION ENGINES Filed July :5, 1941 5 Sheets-Sheet 1 July 10, 1945- H. G. CAMNER 2,380,143

FUEL INJEGTING MEANS FOR INTERNAL-COMBUSTION ENGINES Filed July 3, 1941 5 Sheets-Sheet 2 9%! a \\\& m V A g.

y 1945. H. G. CAMNER 2,380,148

FUEL INJECTING MEANS FOR INTERNAL-COMBUSTION ENGINES 5 Sheets-Shet 5 Filed July 3, 1941 July 10, 1945. H. G. CAMNER 2,380,148

FUEL INJECTING MEANS FOR INTERNAL-COMBUSTION ENGINES Filed July 5, 1941 5 Sheets-Sheet 4 E uz 3 3 5.51 Trgz.

July 1945. H. G. CAMNER 2,380,148

FUEL INJECT-ING MEANS FOR INTERNAL-COMBUSTION ENGINES Filed July 3, 1941 5 Sheets-Sheet 5 Patented July 10, 1945 FUEL INJECTING MEANS FOR INTERNAI;

COMBUSTION ENGINES Hilding Gunnar Camner, Ektorp, Sweden, as Skill)! 'Aktiebolaget A5188 D1886], Stockholm,

Sweden Application July 3, 1941, Serial No. 400,946

In Sweden July 8, 1940 11 Claims. '(ci. zoo-m In internalcombustion engines, above all, high speed engines with direct fuel injection, it is very difficult to attain a smooth operation and desired control with the injection valves-now generally used. The difficulties are due to the fact that the valve spring must be loaded to a comparatively high pressure, in order that the valve shall permit of being closed rapidly so as to overcome the pressure of the gases in the combustion chamher after the fuel pump-has been unloaded.

Through the high loading pressure the atomization will keep rather constant during the injection period. When the ignition then commences, it therefore takes place well-nigh in the way of an explosion, which involves a rough operationof the engine. l

At a lownumber of revolutions and a low load, the high loading pressure is disadvantageous also from the point of view of control. By reason of the volume of the fuel pipes and the fuel pump, and on account of by-leakage within the fuel pump, the difficulties in obtaining accurately adapted injection quantities are increased. In idle running, above all, it therefore frequently occurs that the engines are caused to operate at fluctuating speed. 1

The present invention has for its object to obviate the above mentioned drawbacks, and substantially consists in that the oil pressure from the fuel pump-is caused to actuate thespring of the injection valve by the aid of at least two pressure members movable in separate chambers communicating with the fuel pump, one of said with this invention. Fig. 1 is a longitudinal section of a fuel pump and an injection valve con nectedthereto according to one embodiment.

Fig. 2 is a similar section according to a modified construction. Fig. 3 is a longitudinal section of an injectionvalveaccording to a second construction, and Fig.'3a is a section of an appurtenant detail taken on a plane forming an angle tothe sectional plane according to Fig. 3. Figs. 4 and 5' show'longitudinal sections of a portion of the fuel pump according to some modified embodiments.

Fig. 6 is a longitudinal-section of an injection valve with a fuel pump built together therewith directly. Figs. '7, 8 and 9 showisome embodiments "of a needie-valve member. Fig. 10 shows a longitudinal section of a fuel pump to a a pump head in known manner.

The injection valve is designated by 9 and the farther embodiment. Fig. 11 is a longitudinal section of aninjection valve-according to still further modified embodiment, and Figs. 12 and 13 are similar sections of two further modifications of the injection valve.

The fuel pump shown in Fig. 1 is of known construction and consists of the pump housing I with the piston 2 operating therein and with was sages I communicating with a fuel container (not shown) and the pump chamber it. :A pressure valve 6 actuated by a spring 5,is. arranged in the atomizer thereof by Ill. The outlet through the atomizer is controlled by a needle valve member i'l constructed as a differential piston having the smaller piston i2 arranged in a lower chamber l3 and the larger piston H in an upper chamber ii. The chamber is communicates with the fuel pump chamber l8. through a passage IS in the valve housing, a conduit i1 and the outlet conv trolled by the pressure valve 8, while the chamber I5 is in direct and permanent communication with said pump chamber'through a passage I9,

2 closes the passages l, 3 in the pump housing,

the pumping commences so as to cause the fuel to flow past the opened pressure valve 8 through the conduit I1 and the passage it into the cham-- her I: of the atomizer ID, as well as through the passage II, the conduit 20, and the passage i 9,

into the chamber iI-undemeath the larger piston ll of the injection valve. When in the chamhers I! and I5, operating in parallel, the pressurehas risen to a value exceeding the pressure of the spring 22, the needle will open the outlet ports of the atomizer ill, so that the injection into the engine cylinder commences. On account of the construction of the needle valve as a differentiai piston having ,the fuel pressure acting on both pistons, the requisite opening pressure will be comparatively low, andby the resistance of the atomizer-outlets the fuel pressure will be successively increased during the continuedinjection... At the termination of the injection, when the pump piston 2 uncovers the passages I and the fuel pump is suddenly'relieved of pressure, the pressure'on the piston ll of the injec- "tion vaive'will disappear almost entirely. inasmuch as the piston chamber I5 is in direct open communication with the pump chamber l8.

This involves that, in difference from the arrangements hitherto known, the opening pressure can be kept very low. When the pressure on the fuel is augmented during the continued injection, the atomizationof the fuel will become different at the commencement and the termination of the injection so that, when the ignition sets in, all of the all particles will not be combusted at the same rate, a more extended combustion being obtained instead, whereby the rise of the pressure within the engine cylinder becomes less violent and the operation of the engine softer in consequence" thereto. In idlerunning and at low loads, more uniform injections will be obtained by reason of the low pressure, which brings about animprovement as regards the control.

By dimensioning the spring 5 in a manner such that the valve 6 will open only at a higher pressure than does the needle valve II, a pre-injection may be effected through the expansion of the fuel as soon as the needle valve opens, provided the remaining pressure in the chamber l3 and in the passages l6, I1 is higher than the gas pressure within the engine cylinder. The principal injection will set in only after the pressure in the pump has risen to a value exceeding the pressure of the spring 6.

The quantity of the pre-injected fuel will depend, in addition to the magnitude of the remaining pressure, on the volume of the passages l3, l6 and II. The time between the pre-injection and the principal injection is dependent on the volume existing in the pump chamber, the passages I9, 20, and they chamber 15.

The pro-injection may entail a combustion still more extended, whereby the operation of. the engine is further improved.

' cylinder will penetrate into the chamber ll a so as to heat the fuel in said chamber.

moment after the opening of the needle valve When the injection is then taking place, the first fuel particles will be caused to ignite at a much earlier stage than the remainder of the injected fuel. Hereby a successsive combustion will be obtained, which brings about a smoother operation of the motor.

Figs. 3 and 3a show another embodiment, wherein corresponding details have been given the same reference numerals as in Figs. land 2.

Here, the needle valve proper is of a different construction, inasmuch as the needle I l with the piston l2 and the piston H are made as separate parts with a certain radial clearance provided between the two pistons. The object of this arrangement is to facilitate the fitting of the two pistons into their guideways, in case complete concentricity would not exist in the manufacture of the valve body and the piston guideways. The separate external piston is tightly pressed by means of a spring 23 "against an annular abutment 24 on the piston l2,-so that the two pistons will act as a unitary differential piston. This valve construction is shown in detail in Fig. 8.

In the embodiment according to Figs. 3 and 3a,

the injection valve is further provided with a 29 provided in the valve housing, said passage communicating with the fuel pump through the passage l6 and the conduit H. The annular passage 29 furthermore communicates directlywith the chamber l5 underneath the larger valve pis- 4 ton I! through a passage 30, Fig. 3a. Here, the

The embodiment shown in Fig. 2 differs from that one according to Fig. 1 only in that a further valve is provided in the conduit between the pump chamber l8 and the valve chamber l3, said valve being constituted by a pressure reducing valve 8 actuated by a spring I and intended at the unloading of the pump primarily to bring about a reduction of the pressure in the chamber l3 and the conduit l6, l1 and then tomaintain a desired pressure therein.

This pressure will stop at a value determined by the tension of the spring I. The pressure on the piston I 4 having been removed, and the power of the spring 22 being thus only counteracted by the pressure on the piston l2, the valve I I will be capable of closing at a pressure in the chamber I 3 exceeding the opening pressure to a substantial extent. It will thus be possible to bring about a sure and rapid closure of the communication to the engine cylinder, even if the openingpressure on the injection valve would be lower than the pressure within the said cylinder.

The spring 1 acting upon the pressure reducing or return valve} may be loaded in a manner such that the remaining pressure in the chamber I3 is kept somewhat higher than the maximum pressure in the engine cylinder, so that the gases in the latter are prevented from entering the injection valve.

It is also possible, however, to choose the tension of the spring I so that the remaining pressure in the chamber l3 becomes lower than the? compression pressure in the engine cylinder prevailing prior to the opening of the needle valve.

In this case, the air compressed within the injection valve has a single connection only with the fuel pump, that is to say the conduit l1 forming a common inlet to the two chambers l3 and I5. Consequently, no separate supply conduits, as in the embodiment according to Fig. l or 2, are required here, the passage IS in the fuel valve, the conduit 20 and the passage 2| in the tirely valveless, as shown in Fig. 4, or may be provided with a pressure reducing valve 3 I, as shown in Fig. 5.

If the fuel pump is entirely without valves, particularly without a pressure valve, a feed pump should be employed, which maintains a pressure of a few atmospheres on the supply conduit to the fuel pump. i

In the embodiment according to Fig. 3, the pressure valve 26 serves to out off the injection chamber l3 from communication with the fuel pump at the unloading thereof, whereas the return valve 26 may replace a corresponding valve in the fuel pump. Here, the spring pressure on the valve 26 may be selected of such a value that, when the return passage 28 is cut off, the remaining pressure in the atomizer chamber It will exceed the maximum pressure in the engine cylinder. If a return valve is provided in the fuel pump'according to Fig. 2, spring I of such valve should. have a lighter tension than the return valve 26. v

The spring tension for the pressure valve2l may then, as in the pressure valve 6 according to Fig. 1, be selected so that the valve 26 is caused to open only at a higher pressure than does the pump according to Fig. 5, in combination with 'a fuel valve according to Figs. 1 or 3, 3a, the valve 3| .maybe constructed as a pressure reducing valve, a's'shown in Fig. 5. To this end, the valve 3| is provided in known manner with a cylindri'-' cal portion 32 making a tight fit with the surrounding wall of the pump head I.

' Here, at-the pressure strokeo'f the pump, the

pressure valve ll mustflrst be lifted to such a level that the lower edge of the cylindrical portion' 32 is brought. above the valve seat, before the valve admits the fuel to the injection valve. Wh h fuel pump is then unloaded, the valve is moved back b'y'the spring 5 and the pressure in the conduit to the injection valve so as to cut oil the passage at the valve seat, as soon as the lower edge of the cylindrical portion 32 moves below said seat. The valve 3| then moves a further distance downwardly, until it bears on the 43 is actuated by a spring 41 and, in turn, actuates V seat. Hereat, the volume of the pressure conduit is' augmented, which results in that the in the conduit drops. (1

Otherwise, the effectof the injection valve acpressure according to any of the embodiments in accordance withFigs. 1, 2, 4 and 5 is in principle the cording to Figs. 3, 3a combined with a fuel pump same as that described in connection with the V embodiment according to Fig. 1, because, when the needle valve is opened, the fuel pressure will at the same time act upon the pistons l2 and H, while at the relieving of the fuel pump the larger piston will also be relieved of pressure.

The valves 25 and 2B in Fig. 3 may also be replaced by other valves, for instance of a pressurereducing type, such as the valve 3|, 32 according to Fig. 5.

Fig. 6 shows an embodiment wherein the injection valve and the fuel pump are built together. Here, a channel system 33 leads from the pressure chamber I 8 of the pump to an annular channel ing. The channel 34 is, through a passage 35.111 direct communication with the chamber I5 undertype and effect as the valve shown in Fig. 5. This fuel pump may preferably be used in connection with aniniection valve of the type shownin Figs. 1 and 2.

'Fig. 11 shows an embodiment of an injection valve with two entirely separate controlling pistons, that is to say, the ordinary piston l2 on the needle valve I I, as well as a second piston 43, the piston chamber 44 of which is formed, in theembodiment shown, in the ordinary screw plug 45 while communicating through a passage 46 with the conduit I6, I! to the fuel pump. The piston the compression spring 22 of the needle valve through a plate l8. Otherwise, the injection valve is constructed in the same manner as in the embodiment according toFig. 3, with a pressure valve 25 and a return valve 28, and with a supply passage 21 to the piston chamber l3 and an outlet passage 28 therefrom.

' The opening pressure for the needle valve H is determined by the tension-0f the spring 22 thereof. This tension is determined here by the compression. spring 4! loading the piston 43 and thus indirectly the needle valve spring 22. At the pressure stroke of the fuel pump the fuel pressure will act partly on the piston 43 and partly, after the pressure has opened the valve 25, on the piston l2. By the pressure on the piston 43 the latter will be moved upwardly, the spring pressure .on the needle valve being thus reduced, which results in that the latterwill open the connection through the atomizer H) at a comparatively low pressure. When the fuel pump is relievedcf pressure, the pressure in the piston chamber 44 ceases entirely or in part, in the same manner as in the piston chamber i5 according 1 to the embodiments abovedescribed, and the piston 43 is moved by the spring ll into its lower a 34 formed in the lower portion of the pump hQusspring tensions chosen, the needle valve will close at a pressure in the chamber 13 equalling or exceeding the opening pressure for the needle valve.

Here, too, the spring tension for the pressure valve 25 may be selected so, if desired, that preinjection is caused to take place.

neath the larger needle'valve piston, and is also,

through an outlet controlled by a pressure valve 36, in communication with a second annular channel 31 formed in the housing of the fuel valve, said latter channel communicating through a number'of passages 38 with the chamber I3 in l shown in detail in Fig. 9, and has the same object as the construction according to Fig. 8. The effect of the combinedfuel pump and injection valve is-the same as that one above described.

Fig. 10 shows a fuel pump which, like that one according to Figs. 1 and 2 respectively, has two separateoutlet conduits l1 and 20,- the first of which is valve-controlled, while the second is in direct open communication with the pump chamherll: However, the pressure and return valves have been replaced here by apressure reducing valves]; 32 with pressure reduction of the same piston only, that is to say the upper larger piston H, which will thus primarily take care of the opening of the needle valve. As soon as this valve and also the pressure valve 25 have been opened, the needle-I I proper will act as a pressure piston, however.

In the embodiments of the injection valve above described, an outwardly opening needle valve has been made use of. Obviously, however, the valve may be of some other construction, for instance of the inwardly opening type, as shown in Fig. 13. Here, the valve spindle 29 is provided at its in-' ner end with a conical valve body 50 cooperating by a spring 5 l. Arranged at the upper end-0f the valve spindle 48 is a piston 53 displaceable within a space 52, said piston being adapted to be actuated for upward movement by a compression spring 54. v

The fuel enters from the pump, which may be of any of the constructions above described,

through the passages l1, l6 into the piston space 52, from which leads a passage 55 to the pressure valve 25, at the opening of which the fuel is 4 2,sso,14e

conducted through. the passage to the lower chamber l3. Return fuel escapes through the passage 28, to which may be connected a return valve in the manner shown in Fig. 3, for example. Leaking fuel may escape through a passage 58. The effect of this arrangement is the same as that described for the embodiments indicated will take place quickly. Here, too, pre-injection may be caused to take place by suitably dimensioning the spring actuating the pressure valve 25. No special atomizer openings have been shown here.

Obviously, the invention is not limited to the embodiments above described and illustrated, in-

asmuch as the injection valve proper with tie ap-.

pertaining piston device, as well as the pressure and return valves cooperating therewith, may be varied in regard to their construction and arrangement within the scope of the invention. Thus the larger auxiliary pistons as illustrated may be replaced by bellows, diaphragms or similar pressure members. Likewise, more thantwo pressure members may be brought into use.

In combination with the valve constructions as illustrated, a further improvement may be obtainedby forming the fuel pump cam 42, Figs. 1 and 6, to a suitable shape, for instance by imparting to the same a' slight rise at the beginning of the pump stroke and a more pronounced rise in the continuation thereof, and, again, a slighter rise toward the end of the stroke corresponding to the highest load.

What I claim is:

1. A fuel injectiondevice including a fuel pump of the kind operative to provide a rising fuel pressure and then a sudden pressure drop, a fuel injection valve housing having means forming an injection chamber and a passageway leading from said chamber to injection ports, a valve member movable in said housing and so associated with 2. Fuel injection device as claimed in claim 1 in which the valve device between the injection chamber and the working space of the fuel pump 'has means associated therewith to provide f'll the reduction of the fuel-pressure in the injec tion chamber and then to maintain said predetermined minimum pressure therein.

3. Fuel'injection device as claimed inclaim 1 in which the valve device between the injection chamber and the working space of the fuel pump has means associated therewith to causethevalve device to open in a direction toward the injection chamber upon a higher pump pressure than the pressure required to open the valve member, in order to effect a preliminary injection.

4. Fuel injection device as claimed in claim 1 in which the valve device between the injection chamber and the working space of the fuel pump comprises at least two valves connectedfin parallel, one for admitting fuel to and one for releasing fuel from the injection chamber, the latter of said valves being a portion of said means for maintaining said predetermined pressure in said injection chamber.

5.Fuel injection device as claimed in claim 1 inwhich the valve device between the injection chamber and the working space of the fuel pump comprises at least two valves arranged in parallel, one for admitting fuel to the injection chamber and one for releasing fuel from the injection chamber and in which the valve for releasingv fuel from the injection chamber has means associated therewith for loading it to first reduce the fuel pressure in the injection chamber upon the falling pressure and thereafter maintain said predetermined minimum pressure in said chamber.

6. Fuel injection device'as claimed in claim 1 in which the valve device between the injection valve seat means in said passageway as to control flow of fuel through said passageway, loading means acting'on said valve member in such a' direction .as to close said passageway, means providing a. communication between said injection chamber and the working space of the pump,

means forming a second chamber in said housing movable in said second chamber and exposed said opening force being reduced by flow of fuel from said second chamber to the working space of the pump upon said sudden pressure drop in said working space to thereby rendersaid loading means effective for closing said valve member, and a valve device in communication with the injection chamber and the working space of the pump to maintain a predetermined minimum fuel pressure in the injection chamber while said passageway is closed. 1

chamber and the working space of the fuel pump comprises at least two valves arranged in par allel, one for admitting fuel to the injection chamber and one for releasing .fuel from the injection chamber and in which the valve for releasing fuel from the injection chamber has means associated therewith for loading it first to reduce the fuel pressure in the injection chamber to a value below the pressure outside the injection chamber and a passageway leading from said chamber to injection ports, a valve member movable in said housing and so associated with valve seat means in said passageway as to control flow of fuel through said passageway, a spring acting on said valve member in such a direction as to close said passageway, means providing a communication between said injection chamber and the working space ofthe pump, means forming a second chamber in said housing separate from said injection chamber, means connecting the second chamber with the. working space of the pump, a piston movable in said second chamher and exposed through said connecting means to fuel pressure from the working space of the pump, said piston being associated with said valve member to exert thereon in response to rising pressure in said second chamber an opening force acting in opposition to the closing force exerted thereon by said: spring and operative upon such rising pressure to cause said valve member to move to open said passageway, said opening force being reduced by flow of fuel from said second chamber to the working space of the pump upon said sudden pressure drop in said working space to thereby render said spring effective for closing said valve member, and a valve device in communication with the injection chamber and the working space of the pump to maintain a predetermined minimum fuel pressure in the injection chamber while said p'assageway is closed. 7

8. Fuel injection device as claimed in claim 1 in which a pressure responsive means is provided in the injection chamber operative in conjunction with the pressure responsive means of said second chamber to open the valve member in response to a rising fuel pressure.

' 9. Fuel injection device as claimed in claim' 1 in which a diflerential piston displaceable in said injection chamber and in said second chamber constitutes said pressure responsive means operative to open said passageway in response to rising fuel pressure in said chambers.

10. Fuel injection device as claimed in claim 1 in which the valve device between the injection chamber and the fuel pump is located in the fuel injection valve housing.

11. Fuel injection device as claimed in claim 1 in which the fuel pump is provided with an operating cam shaped to provide a slight rise at the beginning of a pump stroke and increasing rise thereafter and a decreasing rise toward the end of that part of the pump stroke corresponding to maximum load,

HILDING GUNNAR CAMNER.

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