DE2062420A1 - Electromagnetically actuated fuel injection valve for an internal combustion engine - Google Patents

Description

2062A20

December 17, 1970 Iir / Sz

Attachment to

Patent imd

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ROBE RT BO S CH GMBH, Stuttgart

Electro- magnetically actuated fuel injection valve

for an internal combustion engine

The invention "relates to an electromagnetically actuated injection valve for a time-controlled fuel injection system an internal combustion engine, in particular an internal combustion engine with manifold injection, its under the force of a closing spring standing nozzle needle seated on the movable armature of an electromagnet in the idle state with a sealing edge or Sealing surface rests against a seat in the spray head of the valve and a nozzle bore coaxial to the axis of the nozzle needle closes in the spray head of the valve.

209826/0431

BATH ORIGINAL

Robert Bosch GmbH R. 144 Lr / Sz

Stuttgart

In known injection valves, the nozzle needle is attached to the armature of an electromagnet, to which a magnet winding and a fixed iron core in this winding as well as part of the valve housing made of soft iron belongs. To that Valve for the respective operating conditions of the internal combustion engine Bring an adapted period of time into its open position, the excitation winding of the electromagnet are electrical Pulses are supplied, the duration of which is determined by an electronic control unit. Because of their relative large armature mass and the comparatively high inductance of the electromagnet leave the known electromagnetic valves an exact metering of the fuel under constant pressure with sufficient accuracy is then no longer possible, if the opening time is selected to be less than about 1 millisecond. For this reason, the known electric fuel injection systems only a single injection process for each individual work cycle of the internal combustion engine intended. To reduce the emission of harmful exhaust gases, it would be advantageous if the for a single work cycle required amount of fuel on several accordingly shortened injection processes could be divided.

The invention is based on the object of creating an injection valve with which the out of the valve during an injection process escaping fuel quantity can also be dosed precisely if the opening time of the valve is only 1 millisecond or less. For this purpose, in the case of an injection valve of the type described at the outset, according to the invention provided that the nozzle needle or the anchor in the center of a - preferably flat - is attached to the membrane its edge is clamped in the valve head. This results in a very exact radial guidance of the nozzle needle and consequently A good sealing effect even with a small closing force

- 3 209826/0431

Robert Bosch GmbH R. 144 Lr / Sz

Stuttgart

on the valve seat. In connection with a reduction in the clamping force is it possible to measure the mass of the armature and the nozzle needle to reduce the size and thereby achieve a more favorable dynamic behavior.

A particularly advantageous development results from the fact that two im for guiding the nozzle needle or the armature Axially spaced apart, preferably made of metal membranes are provided, each on their Edge in the housing of the valve or in the valve head are clamped and advantageously run parallel to each other.

Further details and expedient refinements result from the embodiment described below and shown in the drawing, a double diaphragm solenoid valve, that in its axial longitudinal section and in a greatly enlarged Scale wj / d it is given.

The solenoid valve has a tubular housing 1 made of steel with an integrally formed neck 2 in which it is coaxial a pipe section 3 forming the iron core of the electromagnet is pressed into the housing. This contains in his as Connection for a not shown fuel supply line Serving end section has a fine-meshed screen 4 and has in the area of its other, the axially movable armature 5 facing End section several radial incisions 6, which to reduce the eddy currents occurring and the flow of the fuel. Coaxially to the iron core 2 is a bobbin 7 pressed from plastic together with the one on it wound excitation coil 8 arranged.

209826/0431

Robert Bosch GmbH R. 144 Lr / Sz

Stuttgart

With the anchor 5 described in more detail below is a Nozzle needle 10 connected, which ends in a slightly conical injection pin 11 and a sharply defined sealing edge 12 on Has transition from the cylindrical shaft of the nozzle needle into the injection pin and with this sealing edge against a conical or spherical seat 13 rests, which is not in a further designated coaxial nozzle bore, through which the spray pin 11 protrudes.

So that the nozzle needle 10, which is under the pressure of a coaxial closing spring 15, is exactly concentric to the spray head and the nozzle bore can be guided and secured against inclination or even tilting, two are in proportion large axial distance from each other arranged flat membranes 20 and 21 provided, in the center of which the armature 5 together the nozzle needle 10 is attached.

The thread on the nozzle needle is used for the exact setting of the needle stroke, whereby the thread play is dimensioned so large that that the needle is centered under the action of the closing spring 15 to the seat 13 can adjust. Both settings, The stroke and central position are determined by the adhesive layer 37 secured.

The armature 5 itself is made to achieve a low mass composed of several parts made of aluminum, namely from a threaded bushing 24, which the threaded pin the nozzle needle 10 receives, and from a spacer sleeve 2'7, which the two flat membranes 20 and 21 in the predetermined Keep your distance. Only the armature plate 28 opposite the iron core 3 is made of soft iron and is shown in FIG Arrangement with the two membranes, the spacer sleeve 27 and the threaded sleeve 24, glued.

- 5 ~

BATH ORIGINAL

2 0 9 S 2 B / 0 A 3 1

Robert Bosch GmbH R. 144 Lr / Sz

Stuttgart

The two membranes are interposed at their outer edge between a soft iron pole ring 32 and the extrusion head 16 two spacer rings 35 and 36 clamped.

When the solenoid valve is not energized, the armature plate 28 is at its central bore 30 with radial incisions 31 provided for the passage of the fuel and the inference of the lines of force serving pole ring 32 with a distance of only about 60 * 10 "* * ^ mm. This den The distance limiting the maximum stroke of the nozzle needle ensures that with a small electromagnetic excitation (number of ampere turns) high tensile forces can be achieved and the winding diameter of the coil 8 can be selected to be very small. This results in very short rise and fall times of the anchor, which make it possible to open times of less than one millisecond and, despite these very short injection times, an exact relationship between the duration of the to achieve the electrical pulses used to open the valve and the amount of fuel then injected.

BATH ORIGINAL

20982R / 0A31

Claims (6)

Robert Bosch GmbH R. 144 Lr / Sz Stuttgart claims 1.) Electromagnetically actuated injection valve for a time-controlled fuel injection system of an internal combustion engine, in particular an internal combustion engine with manifold injection, its under the force of a closing spring standing nozzle needle seated on the movable armature of an electromagnet in the idle state with a sealing edge or Sealing surface rests against a seat in the spray head 'of the valve and is coaxial with the axis of the nozzle needle The nozzle bore in the spray head of the valve closes, characterized in that the nozzle needle or the armature is attached in the center of a membrane, which is clamped at its edge in the housing of the valve or in the valve head. 2. Injection valve according to claim 1, characterized in that that for guiding the nozzle needle or the armature two axially spaced apart membranes, in particular Flat membranes (21, 22) are provided, the edge zones of which, preferably with the interposition of a spacer ring (35) are braced against the housing or the spray head (16) of the valve. BATH ORIGINAL 209826/0431 Robert Bosch GmbH R. 144 Lr / Sz Stuttgart 3. Injection valve according to one of claims 1 or 2, characterized in that the nozzle needle (10) has an armature (5) νerschraubbaren threaded pin (25) has. 4. Injection valve according to claim 3, characterized in that the central position of the nozzle needle (10) to the seat surface (13) is secured by an adhesive layer (37). 5 · Injection valve according to one of claims 1 to 4, characterized characterized in that the armature consists only of its end portion facing the core (3) and pole ring (32) Soft iron is made. 6. Injection valve according to claim 5 »characterized in that that the armature (5) has an armature plate (28) with only a small overall axial length - preferably in the form of a disk, but otherwise made of light metal-1. 2 0 9 8 2 Γ> / 0 4.3 1 Blank page