US2471605A - Pressure controlled injection valve - Google Patents

Description

May 31, 1949.

J. J. BROEZE PRESSURE CONTROLLED INJECTION VALVE Fig.

Filed June 30, 1947 lnvzn'l'or:

Johannzs J. Broezz His A++orneg Patented May 31, 1949 2,471,605. I rmsssons CONTROLLED mmcrron VALVE Johannes J. Broeze, Delft, Netherlands, assignor to Shell Development Company, San Francisco, Calif., a corporation of Delaware Application June 30, 1947, Serial No. 758,107 In the Netherlands January 3, 1947 7 Claims. (Cl. 137-153) This invention relates to atomizers for the injection of fuel into the combustion spaces of internal combustion-fengines by means of a fuel injection valve lifted by the fuel pressure such valves being often known as needles or needle valves. More particularly, the invention relates to fuel injection nozzles wherein the fuel injection needle is subjected to a liquid, which, when under pressure, urges the needle to its closed position, i. e., for moving it toward or maintaining it on its seat. Such devices are used for injecting combustion fuel either directly into the engine cylinder or into an auxiliary combustionatomizer chamber connected with the engine cylinder.

With high-speed engines having injection nozales the needle valves of which are lifted by the fuel pressure it is often difficult to achieve satisfactory control of the dynamic operation of the injection system, comprising the fuel pump, the connecting fuel line and injector nozzle. As a I result, the regularity of the fuel injection is often seriously disturbed, particularly when the engines are running at high speed.

It is an object of the present invention to minimize or Obviatethis disturbance and to provide an improved valve arrangement for achieving satisfactory control of the operation of the fuel injection system.

A further object is to provide an improved in- Jector nozzle having a needle valve which is loaded with a liquid confined in a space so as to retard the opening of the needle valve while permitting the rapid closing thereof.

The invention is based upon the discovery that the aforesaid disturbance is chiefly due to the sudden increase in the volume within the fuel system caused by the lifting of the needle valve. Needle valves which are lifted by the pressure of the fuel inherently increase the space occupied by the fuel acting on the valve. When an engine is operating at a high speed this sudden increase in the volume of the space causes a sharp local reduction of the pressure, and, interferes with the pressure wave occurring between the fuel pump and the fuel injection needle; this interference is largely responsible for the disturbance referred to.

In order to avoid the occurrence of this disturbance as far as possible, an atomizer arranged to minimize the sudden increase in the available fuel space is provided according to this invention, wherein the needle valve is subjected to the pressure of a loading liquid acting on at least a portion of the needle and urging the needle to 2 its closed position. This loading liquid is confined within a closed loading space or chamber which has two flow channels: A comparatively wide flow channel through which loading liquid can only flow into the closed loading chamber; and a comparatively narrow flow channel permitting flow into or out of said loading chamber, or, if desired, only out of said loading chamber. .These channels communicate with a reservoir containing a supply of the loading liquid, which might be maintained under pressure. If desired, the narrow flow channel need not be connected to the. reservoir but may have its mouth disposed for discharge to the open or into any other receptacle.

The loading liquid need not be under pressure at all times; thus, when the invention is applied to injectors having spring loaded needle valves,

or spring loading for the needle valve .inay be omitted entirely, the function usually performed by the spring being partially or wholly performed by the loading liquid. In this case it is, according to this invention, preferable to connect both the wide channel and the narrow channel from the loading chamber to the source of liquid pressure, for example, to the aforesaid reservoir. A suitable pressure is then maintained on the loading liquid, as by connecting a pressure regulated feed pump and/or a standpipe to the reservoir. It is preferable in such a case to connect the loading chamber and reservoir by a bore fitted with a back pressure valve with a narrow perforation in it, the latter forming the narrow flow channel.

The invention will be further illustrated with reference to the drawings forming a part of this specification, wherein:

Fig. l is an axial section of an injector embodying the present invention;

Fig. 2 is an enlarged detail view of the valve for controlling the flow of loading liquid; and

Fig. 3 is a cross-sectional view taken on line 3-,3 of Fig. 2. p

The injector comprises a casing l which may, if desired, be formed of several parts; its lower portion 2 is adapted to fit into a well in the engine block leading into the combustion spacev of the cylinder, i. e., either directly into the cylinder or into a connecting atomizing-combustion chamber. The casing has a passage 3 in communication with a hollow or chamber 4 for the supply of fuel which may be fed to the casing by a suitable fuel line attached to a fitting 5. The end of the passage 3 is closed with a plug 0. Fuel from the chamber 4 is discharged into the combustion space via the atomizer ducts 1. these ducts being normally closed by means of a needle valve 8, slidably mounted in a central bore in the casing and having a close fit therewith. The end a of-the needle rests on the portion of the llower wall of the chamber immediately surrounding the central fuel discharge passage to the atomizer ducts I, said portion forming a valve seat. This end of the needle is of reduced crosssection, whereby the annular face at the end of the larger portion is exposed to the pressure of the fuel and the needle may be lifted in response to a rise in the pressure of the fuel in the chamber 4. As is understood in the art, the fuelis supplied from a suitable fuel pump which increases the fuel pressure periodically in synchronism with the engine and is actuated, for example, by a cam device. The pressure rise causes the lifting of the needle and the injection of the fuel into the combination space at the desired instant.

The central bore of the casing is enlarged at a providing a closed hollow space or chamber above the needle which is filled with a loading liquid, such as oil. This chamber is herein referred to as the loading chamber. A further enlarged chamber ill at the top of the casing is also filiedwith loading liquid and is in communication with a source of pressure through a passage H in the top closure l2. This space it forms the reservoir for the loading liquid. The chambers I and ii are interconnected by a bore l3.

Flow of loading liquid through the bore I 3 is regulated by means of a back pressure valve ll provided with radial fins 'II in sliding engagement with the walls of the bore II. It carries a trunco-conical valve head I. adapted to seat upwardly against the lower mouth of the bore i3. being urged upwardly by a spring II. This spring rests on the top of the needle 0 and tends to urge the needle to its seat. The spring I 1 is, 50,

however, in the preferred form of the invention of comparatively light construction, so as to play a minor'part in urging the needle to its closing position, the needle being urged toward its seat mainly by the loading liquid; the spring I! may, if desired, not bear against the needle valve, but rest on a shoulder on the casing I or even be omitted entirely, the needle being then closed entirely by the force of the loading liquid. The valve H in this case rises to its closed position by fluid pressure immediately after the needle valve 0 has started its upward movement. The valve is provided with a bore I which is constricted near the top to form a narrow channel l0.

It will be seen that the chambers 0 and III are interconnected by two channels: The open portion of the bore l3 between the fins l5 forms the wide channel, through which loading liquid can flow freely downwardly into the loading chamber 0 around the valve it between the fins when the head I0 is off its seat; the narrow channel is formed by the bore II and constricted channel l0. Since the spring I! is light, the valve will descend whenever the pressure in the chamber 0 falls below that in the chamber ll, 75 greater or lesser number of parts without depart permitting a rapid downward flow of loading liquid. When the pressure in the chamber 0 is equal to or exceeds that in the chamber l0, however, the spring I! closes the valve and the upward flow of liquid is prevented. Liquid can then flow upwardly only at a slower rate through the narrow channel l9.

The injector operates as follows: The loading liquid in the chamber III is maintained at a pres-' sure :1. As long as the needle valve is in its closed position, the loading chamber 0 is at the same pressure. When the fuel pressure in the passage 3 exceeds a certain value; whichwlll depend upon various characteristics of the injector, such as the size of needle, the stiffness of the spring I] and the pressure p, the valve 8 is lifted.

As soon as the needle valve is lifted the pressure in loading chamber 9 (and. therefore, also the loading on the upper end of the needle) increases sharply, because the loading liquid contained in this chamber can escape only to chamber l0 through the narrow channel is. This channel is so narrow that a considerable resistance against the upward movement of the needle is created.

As a result, the needle valve 8 islifted very gradually, so that the volume of the chamber 4 is increased only gradually and the occurrence of the previously mentioned disturbin interference with the pressure wave in the fuel supply system is entirely or for the greater part obviated.

For closing the needle the full pressure p is available, because the loading liquid can flow from chamber ID to loading chamber 9 without having to' overcome any appreciable resistance. Hence, the needle 8 can close rapidly.

In a practical embodiment the needle diameter above the narrower portion 8a was 4 mm., the lift of the needle 0.2 mm. and the pressure p 200 atmospheres. The quantity of loading liquid which must pass from chamber 9 to chamber i0 through the narrow channel I! when the needle rises will then be about 2.5 cubic mm. If the speed of the engine is 2000 R. P. M. and the opening is to be effected in 6 degrees of travel of the crank, i. e., in 0.5 l0- seconds, the displacement velocity will be 5,000 cubic mm. per second.

If the narrow channel I! is given a diameter of about 0.26 mm., and oil is used as the loading liquid, an increase in pressure of about 50 atmospheres is obtained, which constitutes a considerable resistance against too rapid opening of the needle; this resistance is attained in accordance with the present invention with constructionally controllable means.

The invention can also be applied to injectors wherein the needle is brought to the closed portion or maintained there by means of spring pressure; in this case the loading liquid in the chamber [0 need not be maintained under pressure. However, application of liquid pressure ofiers the advantage that the moving parts of the injector can be designed lighter and the needle cannot be subjected to lateral loading, so that it moves freely within its guides. The pressure p can be obtained by taking some oil from the fuel injection system; the pressure p can be very easily regulated, for example, as a function of the number of revolutions per minute of the engine.

Instead of forming the narrow channel as a bore in the back pressure valve ll, a leakage opening may be provided in the valve head I6 .or in the mouth of the bore II which forms the valve seat.

The injector may, of course, be constructed of a 2,471,coc

ing from the spirit and scope of the invention. Thus, the loading space 9 may be formed in a housing or part which is separate from the cas ing l.

I claim as my invention:

1. A pressure controlled injection valve, for internal combustion engines comprising a casing having an axially extending guide bore, a fuel inlet passage, a fuel chamber at one end of the bore, a fuel discharge passage in said casing leading from said fuel chamber and provided with a valve seat, a loading chamber for loading liquid separate from saidfuel chamber and in communication with said bore, and a reservoir for loading liquid; a valve member having a piston portion within said guide bore coacting with said valve seat for controlling said discharge passage and having a surface facing toward said seat exposed to the fuel pressure in said fuel chamber and a surface facing in the opposite direction exposed to the pressure of the loading liquid in the loading chamber, whereby fuel pressure will tend to open said valve member and loading liquid within said loading chamber will oppose the opening thereof; a narrow fiow channel formed in said casing for the loading chamber adapted to permit the restricted flow of loading liquid out of the loading chamber; and a wider flow channel having a valve adapted to permit the substantially free flow of loading liquid from the reservoir into the loading chamber and prevent the free flow of loading liquid out of the loading chamber.

2. An injection valve as defined in claim 1 wherein the narrow flow channel interconnects the loading chamber and the reservoir.

3. An injection valve as defined in claim 1 wherein the valve in the wider flow channel is a back pressure valve adapted to permit the flow of loading liquid from the reservoir into the loading chamber when the pressure therein is lessv 40 than the pressure in the reservoir.

4. An injection valve as defined in claim 3 wherein the back pressure valve is provided with I narrow perforations forming said narrow fiowchannel.

5. A pressure controlled injection valve for internal'combustion engines comprising a casing having an axially extending guide bore, a fuel inlet passage, a fuel chamber at one end of the bore, a fuel discharge passage in said casing leading from said fuel chamber and provided with a valve seat in axial alignment withsaid bore space, a loading chamber for loading liquid in said chamber at a point removed from said fuel chamber and in communication with said bore, a reservoir for loading liquid also in said casing and a bore connecting said loading chamber and reservoir; a valve member having a piston portion within said guide bore coacting with said valve seat for controlling said discharge passage and having a surface facing toward said seat exposed to the fuel pressure in said fuel chamber and a surface facing in the opposite direction exposed to the pressure of the loading liquid in the loading zchamber; whereby fuel pressure will tend to open said valve member and loading liquid within said loading chamber will oppose the opening thereof; a back pressure valve controlling the flow of loading liquid between the loading chamber and the reservoir adapted to permit the substantially unobstructed flow of loading liquid from the reservoir into the loading chamber; and a narrow flow channel connecting said loading chamber and reservoir and adapted to permit the restricted fiow of loading liquid from the loading chamber'into the reservoir.

6. An injection valve as defined in claim 5 comprising a spring within said loading chamber arranged to urge the back pressure valve and the valve member to their closed positions.

7. An injection valve as defined in claim 5 wherein the narrow flow channel is a perforation in the back pressure valve.

JOHANNES J. BROEZE.

REFERENCES CITED UNITED STATES PATENTS Name Date Miller -a-.. May 13, 1947 Number

Images