Electromagnetic Fuel Injection Spray Valve

Abstract

Valve has a disc-shaped armature with a hollow shaft containing a compressed coil spring that holds the valve proper, carried at the end of the shaft, closed, except when the magnet is energized.

Description

BACKGROUND OF THE INVENTION

The invention relates to an electromagnetic fuel injection spray valve for internal combustion engines.

The electrically operated fuel injection devices of the prior art for internal combustion engines comprise an electromagnetic fuel injection spray valve which is opened, in dependence on the r.p.m., by an electronic control for a predetermined length of time, this period being dependent on various operating parameters of the engine, including r.p.m., throttle valve setting, and the suction in the induction pipe.

Fuel under pressure is continuously fed to the housing of these injection spray valves. As soon as the magnet coil is energized, the valve proper, connected to the magnet armature, frees the path to the spray nozzle, and fuel is sprayed into the induction pipes of the engine, for example.

In one fuel injection spray valve of the prior art, the armature is designed as a cylindrical piston that projects into a cylindrical magnet coil and is moved against the resistance of a coil spring which biases the valve closed, the spring also being arranged within the magnet coil.

An injection valve of this kind operates satisfactorily at low fuel pressures, such as 2 atmospheres. But at higher fuel pressures, such as 20 atmospheres, the magnetic force is not sufficient to raise the small cylindrical piston.

In another injection valve of the prior art, the valve embodies a disc-shaped armature and a horseshoe magnet. The magnetic force acting on the armature is substantially greater in this case, permitting higher fuel pressures and, therefore, shorter injection times. A diaphragm spring, held tensed in the valve housing, serves to close the valve. The spring, however, is very stiff; and it has been observed that the valve-closing force is greatly dependent on outside factors, such as thermal expansion, so that proper operation of the valve is adversely affected.

SUMMARY OF THE INVENTION

An object of the invention is to provide a fuel injection spray valve that possesses the advantage, but not the disadvantages, of these two prior art valves, and that is simple and inexpensive to manufacture.

The invention relates to an electromagnetic fuel injection spray valve, including a valve proper, a spray nozzle opened and closed by the valve, a disc-shaped armature for operating the valve, and wherein the improvement comprises a cylindrical hollow shaft incorporated by the armature, the valve proper being associated with the free end of the shaft, and a coil spring in the hollow of the shaft for biasing the valve to its closed position.

The use of a coil spring, for closing the valve, in combination with a disc-shaped armature ensures a strong magnetic force and the greatest possible independence from outside influences.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described, with reference to the FIGS. of the accompanying drawings, wherein:

FIG. 1 is a longitudinal section of one embodiment;

FIG. 2 is a view taken along line II-II of FIG. 1;

FIG. 3 is a view taken along line III-III of FIG. 1;

FIG. 4 is a longitudinal section, taken at right angles to that of FIG. 1, of an embodiment having a modified armature.

FIG. 5 is a view taken along line V-V of FIG. 4;

FIG. 6 is a longitudinal section of another modified armature;

FIG. 7 is a top view of the armature seen in FIG. 6; and

FIG. 8 is a longitudinal section of a third modification of the armature.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The fuel injection spray valve shown in FIG. 1 has a housing comprising two parts 1 and 2. Within the housing is a magnet coil 3, which is wound on a synthetic Plastic former 4 and surrounds a laminated metal core 5 (see FIG. 2). The laminations form a rectangular core (as seen from above) held together by the former 4. The four corners of the core touch the round housing part 1 and hold the core centered within the housing 1 and 2.

The housing part 2 incorporates a bore 6 for the shaft 7a of a disc-shaped armature 7. The shaft is cylindrical and hollow, and carries at its lower end a valve 8 that cooperates with a valve seat 9 and periodically opens and closes the path for the fuel to the spray nozzle 10. Within the hollow of the shaft 7a is a coil spring 11, which presses against a slider 12 that, in turn, presses directly against the magnet core 5. The spring 11 is compressed, and urges the armature 7, the armature shaft 7a, and the valve 8 at the end of the shaft 7a downwards against the valve seat 9. An annular spacer 13 made of a nonmagnetic material, such as a synthetic plastic, is arranged between the armature 7 and the core 5 in order to prevent the latter two from touching each other and so to reduce the residual magnetism.

The spacer 13 can also be star-shaped, as indicated by the dashed line in FIG. 3.

A fuel supply line 14 is connected to the housing part 1, the fuel under about 20 atmospheres pressure entering the interior of the housing 1 and 2, passing through the bore 15, and entering the annular chamber 16, from which latter it is injected through the spray nozzle 10 and into the induction pipes of an engine, for example, whenever the valve 8 is raised from its seat 9. To equalize the pressure, other bores 17 and 18 connect the hollow of the shaft 7a with the interior of the housing 1 and 2. The magnet armature 7, with its shaft 7a, is so fitted in the housing 1 and 2 that it is raised about 0.1 to 0.2 mm. whenever the magnet coil 3 is energized. A threaded ring 19 presses the housing part 2 directly against the magnet core 5. The necessary compression of the spring 11 can be easily adjusted before assembling the fuel injection valve by suitably dimensioning the slider 12, for example. The stroke of the armature 7 is determinal by the dimensions of the housing part 2 and of the armature with the spacer 13.

The face of the armature adjacent to the core 5 is advantageously slightly conical, in order to facilitate movement of the fuel between the armature and the core when the armature rises.

In the embodiment shown in FIGS. 4 and 5, the housing upper part 1 with the core 5 and coil 3 is substantially similar to the embodiment shown in FIGS. 1 to 3; but the housing lower part 2 is pressed or squeezed into the upper part 1. A separate spacer 21 is arranged between the core 5 and the housing part 2; the spacer 21 tangentially guides the armature 7 in its throw, and the thickness of this spacer adjusts the armature's stroke. In this embodiment, the armature 7 is still disc-shaped but no longer circular in outline; instead two opposite segments have been removed to reduce its weight.

Eddy currents are largely suppressed by incorporating milled parallel slots 22 in the armature 7.

In another embodiment shown in FIGS. 6 and 7, the armature 7 includes the hollow shaft 7a with its compression spring 11 and laminations 24 riveted onto a crosspiece 23, the laminations 24 constituting the disc-shaped armature 7. This manner of forming the armature 7 of laminations also reduces the appearance of eddy currents.

In still another embodiment, shown in FIG. 8, the hollow shaft 7a with its valve 8 is made of steel, and the disc-shaped armature 7 is made of soft iron and cemented or welded to the shaft 7a. The interior of the shaft 7a houses the compression spring 11, which presses against an intermediate ring pressing against the slider 12, which contacts the magnet core.

Although the preferred embodiments of the invention have been described, the scope of, and the breadth of protection afforded to, the invention are limited solely by the appended claims.

Claims

I claim:

1. An electromagnetic fuel injection spray valve, including a valve proper, a spray nozzle opened and closed by said valve proper, a disc-shaped armature connected to said valve proper for operating the latter, and wherein the improvement comprises a cylindrical hollow shaft incorporated by said armature, said valve proper being associated with the free end of said shaft, a coil spring in the hollow of said shaft for biasing said valve proper to its closed position, a slider (12) slidable in the hollow of said shaft, and a magnet core, and wherein said coil spring presses on said slider against said core.

2. The injection valve as defined in claim 1, including a cylindrical housing for the fuel injection valve, and wherein said core is within said housing and has the form of a laminated magnet core that is rectangular in cross section, and the four corners of said core touch said housing to center said core inside said housing.

3. The injection valve as defined in claim 2, including a magnet armature, and wherein a face of said armature lies adjacent to said core and is cone shaped.

4. The injection valve as defined in claim 1, including a housing for the fuel injection valve, and a plurality of bores (17, 18) for connecting the hollow of said shaft to the interior of said housing.

5. The injection valve as defined in claim 1, including a housing for the fuel injection valve, and wherein part (2) of said housing guides said armature in its movement and is in direct contact with said core.

6. The injection valve as defined in claim 1, wherein the disc-shaped part of said armature is substantially rectangular and has two straight and two arcuate sides.

7. The injection valve as defined in claim 6, wherein the disc-shaped part of said armature has parallel slots to reduce eddy currents.

8. The injection valve as defined in claim 1, wherein the disc-shaped part of said armature is composed of riveted laminations to reduce eddy currents.

9. The injection valve as defined in claim 1, wherein the disc-shaped part of said armature is made of soft iron and said shaft is made of steel, and further including means for fastening together these two armature parts.