DE2942853A1 - ELECTROMAGNETIC FUEL INJECTION VALVE - Google Patents

Description

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Electromagnetic fuel injector

The invention relates generally to electromagnetic fuel injectors and, more particularly, to an improved seal assembly, which allows a wider range of operating temperatures, primarily when the injector should be operated at temperatures below minus 30 C.

Electromagnetic fuel injectors have been used in fuel metering for both multi-point and single-point systems, where an electronic control system generates a pulse length signal representative of the amount of fuel is, with which an internal combustion engine is to be fed, found widespread use. These injectors do that Opening of fuel metering openings that lead to the air supply paths of the engine by means of a solenoid operated Anchor that responds to the electronic signal. Due to recent developments, these injectors are in their Dosing properties are very precise and they work very quickly. These advantages of the electromagnetic fuel injector represent part of the overall advantages of electronic fuel metering, through which the economy, the development of exhaust gases and the running properties of Internal combustion engines are improved.

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Oa the electromagnetic fuel injection is widely used found, the ambient temperature range over which the injection can be operated must be expanded will. One limitation that applies to valves of the prior art is their mode of operation at cold temperatures, which is due to the sealing properties of the O-rings it contains. Usually these O-rings exist Made of rubber or similar material that can be used at normal room temperatures or remains essentially flexible at elevated temperatures, there are densities between the different ones Injector part materials that are different expanding and contracting volumetric values decrease relatively well. Bsi colder temperatures, especially in the area below minus 30 C, however, they start to become inflexible and quite brittle. At this point the different effect Contraction properties of the injector parts create a separation between the 0-fling and those adjacent to it Flats and, consequently, leakage of the pressurized fuel. It would therefore be beneficial to have an injection valve with a larger operating range at cold temperatures available, in which the O-Hing seal up to a temperature of around minus 40 C is ready for operation.

In order to avoid this disadvantage, the present invention proposes an electromagnetic fuel injector, comprising a valve assembly including a valve housing and a valve element having an armature portion, the

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Vantile element in the valve housing between a closed Position and an open position can be moved to untur Pressurized fuel from niner inlet opening in dum Housing to an outlet opening in the housing, under electric current setzbarti btatureinrichtungem, the innurhulb an injection valve housing are arranged around the valve element to move to the open position by putting in an unstable position of the stator means of the armature section a magnetic field is attracted, and means for moving the valve element to the closed position Interruption of the cord supply for the stature devices, is characterized in that the stator device

a "bobbin arranged in the injection valve housing and

the
Sealing devices comprise / are elastically compressed between a portion of the spool and a portion of the injection valve housing in order to seal the uritor pressure fuel within the injection valve housing, the spool and the injection valve housing having different volumetric Tefflperaturge Expansion coefficients, so that the compression of the sealing devices increases, when the temperature drops.

The invention will now be described on the basis of an embodiment described in connection with the drawing. Show it

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oiooao / oiaö

29A2853

Figure 1 is a side view, partially in section, of one

Einpunkteinspritzsystemsi the one according to the invention trained fast acting electromagnetic injector with high flow rate is provided;

FIG. 2 shows a longitudinal section through that shown in FIG electromagnetic injector;

Figure 3 shows a cross section through the injection valve housing the injection valve shown in Figure 2 along the line 3-3 in Figure 2;

Figure 4 is a graph of the fuel flow

by the valve shown in Figure 2 as a function of the lifting of the valve needle; and

FIG. 5 is a graphic representation of the dynamic fuel flow by the valve shown in Figure 2 as a function of the injection signal duration.

In Figure 1 is a one-point injection system for fuel metering shown for an internal combustion engine. The system includes an electromagnetic injector 10, which is of a connector 12 is electrically connected to a control unit 16 via a series of conductors 14, 16. In

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the control unit 1ü are various transmission parameters of the motor, such as the speed of the motor, the absolute pressure in the intake manifold, the temperature the used air and the coolant temperature of the engine, which happens via conventional sensors.

The injection valve 10 is fitted into a fuel injection sleeve, which is in a single air suction port 34 of a Throttle body 25 is arranged, which is in communication with an intake manifold 42 of the internal combustion engine. For throttle bodies With several air intake holes, one injection valve can be used per hole. The air supply for the The engine is controlled by a throttle valve 30 which is rotatably mounted below the sleeve 22. After scanning the Operating characteristics of the engine, the control unit outputs pulse-length electronic injection signals to the link 12, which are representative of the amount of fuel required for the injection process, ao that the injection valve 10 opens and closes depending on the leading and trailing edge of the signal to remove fuel from the injector sleeve 22 to dose. The fuel is dispensed in a wide-angle spray pattern for optimal mixing with the incoming air and to achieve an optimal delivery into the intake manifold.

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Pressurized fuel is injected into the injector sleeve 22 fed through a fuel inlet 20. The fuel circulates through the interior of the injection sleeve and thereafter to an outlet channel 24 which leads to a pressure regulator 40, which maintains a substantially constant fuel pressure. Used fuel is returned to a memory, for example a fuel tank, from where it is sent to the

s sleeve 22 can be pumped back. The injector is sealed in the sleeve via suitable elastic devices, for example via a D-ring 28 at the lower end the sleeve and an O-ring 26 that rests against a shoulder leaning against the top of the sleeve. The injection valve 10 is fixed by a spring clip 36, which is fixed by a screw 38 is held in place.

Such a single point fuel injection system is special suitable for a 2.2 liter engine with four cylinders. By doing injected twice per revolution becomes an air / fuel charge issued for each cylinder ignition. The injection process takes place preferably at a set angle with respect to a fixed point of the motor, for example immediately before top dead center of the first cylinder on the intake stroke and thereafter with cyclical reference to this Period. The coordination of the injection so that it takes place immediately before the opening of a special inlet valve, makes it possible for a large part of the fuel-air metering to be delivered to the respective cylinder to be injected

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will. This reduces the condensation that occurs and helps to reduce distribution differences in the cylinder to avoid cylinder.

To an injection in a system wi 2 to perform as described above, a single-point injector with a high fuel flow rate of 400-600 cm / min and with an ^r dynamic characteristic which runs millisecond range A linear in the required. The invention provides such an electromagnetic injection valve 10 with an advantageous construction.

In Figures 2 and 3, the injection valve 10 is large Flow shown in section. The valve comprises a housing which has a tubular main part 100 consisting of a a seamed tube or a seamless tube cut into individual lengths. 0s Main part 100 is cold worked at each end, so that a shoulder 101 with a radially offset edge portion 102 formed at the front end and a shoulder 103 with another radially offset edge portion 104 at the rear end will. Oa the tubular main part 100 is a part of the magnetic circuit of the injection valve, acts ea The material used is low-carbon steel tubes. This material has excellent mechanical properties Strength and high permeability. The main part 10

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as well as all other outer surfaces of the injection valve 10 can be treated by conventional methods in order to protect them against environmental influences to protect and make corrosion-resistant.

The valve housing further includes a front end cap and a rear end cap 110. The front end cap 106 is with a cylindrical body with a central bore having a flange which abuts against the shoulder 101 and is fixed by folding or upsetting the edge portion 102 against a bevel 106 provided on the flange. Similarly, the rear end cap 110 includes a a cylindrical body provided with a central bore and having a flange which abuts against the shoulder 103 and there by deforming the edge portion 104 so that it is adapted to a bevel 112 present in the flange of the cap is fixed.

Inside the chamber, defined by the inner wall of the main body and the inwardly facing surfaces of the front end cap and the rear end cap 110 is formed, there is an elongated, molded spool 114 around the magnet wire is wound around so that a coil 116 is formed. The coil 116 comes with a set of connector pins 120 (only one is shown) electrically connected through an oval opening 122 in the rear end cap 110 extend rearward and through a connecting part 118

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zt, which are formed in one piece with the bobbin 114 is.

Oer bobbin 114 has a wittily arranged longitudinal bore 124 which extends substantially coaxially with a threaded bore 126 in the rear end cap. A rod-shaped core member 126 made of soft magnetic Material is screwed into the threads of the end cap bore 126 and extends substantially the length the bobbin hole. The core element 128 is on its own Threaded end 130 slotted for adjustment to allow its extension / coil body bore 124. Adjusting the core element determines the air gap and the lift height of the valve. A set screw 132 is screwed into an inner bore of the core element 128 so that the valve closing force can be adjusted by a pin 140 which moves against a ball element 136. The inner bore the core element 128 is sealed by an O-ring 138, which has slipped over pin 140 and abuts the inner surface of the bore.

The bobbin bore 124 is hydraulically sealed on the inside of the rear end cap 110 by a 0-fling 139 and on the front end cap 106 by a Q-fling 141. These sealing devices are under pressure at normal room temperatures (20 ° C.) between two materials with different thermal expansion and contraction behavior. 0s

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Q-rRing 139 is compressed into an annulus that is between the cylindrical outer surface of the core element 128 and the cylindrical inner surface of the totaled area 127 of the coil body 114 is formed. The O-Hing 141 is in one similar ring area compressed between the cylindrical Outer surface of a rearward extension of the body of the front end cap 106 and the cylindrical inner surface of a recessed area 143 is formed in the bobbin 114.

The end cap 1üG and core member 128 are made of similar low plastic steels, while the Spool 114 is molded from fiberglass reinforced nylon. The cylindrical inner surfaces of the bobbin and the cylindrical Outer surfaces of the end cap and core element all contract radially during a temperature drop. However, due to its different material, the bobbin contracts faster and thus increases the compression at lower temperatures. This rising force exerted by the faster contracting coil body Pressure causes an expansion of the operating range of the valve at cold temperatures by reducing the lack of flexibility of the O-ring seals below minus 30 C is compensated.

A single step is located in the central bore of the front end cap 106, dividing the bore into an anchor guide bore 142 and a mounting bore 144. In the

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Mounting hole 144 is a valve housing 146 so far received until it against the at the step between the bores trained inner shoulder 145 abuts. The valve housing 146 is held in position by the front edge portion of the Mounting hole 144 via a chamfer in valve housing 146 is bent. The valve housing 146 is provided with a longitudinal bore 14Θ, which at one end with the armature guide bore 142 communicates and ends at the other end in a conical valve seat 150, which is in a smooth transition area 152 curves and finally forms a cylindrical metering opening.

Oiβ valve housing bore 148 stands by means of a plurality of Fuel inlets 149 surrounding the valve housing 146 are spaced, with the fuel in the sleeve 22 in connection. The inlets 149 are close to the metering opening 154 arranged so that there is a minimal pressure drop during operation at low pressure. The inlets are also against contamination by the surrounding screen of a molded filter element 151 which is attached to the valve housing is fit, protected.

In the valve housing bore 14Θ a valve needle 156 is back and movably arranged at its distal end by interference fit in a generally annular shaped anchor 15Θ is attached. The needle valve, which is in cross-section in

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Figure 3 has a central portion which is triangular in cross-section and is curved at each angle Forms bearing surface that slides on valve housing bore 146 to center the needle valve within the bore .

The needle valve extends into a valve tip 160 which has a sealing surface 162 that mates with the conical valve seat 150 cooperates to close the Ventilea. A pin extends from the valve tip of the needle valve and is in a Bend cap 164 ends which shapes the injected fuel into a hollow cone or wide angle spray pattern, as above has been described. The deflection cap is received in the housing 146 for reasons of protection.

The needle valve 156 is substantially hollow and has an inner channel 155 which extends from the valve tip to is drilled to the valve end connection on armature 158. The valve end is provided with a recess 147 which is a closing spring 137 is stored within the central bore in the armature 158. The channel 155 protrudes through an opening 153 in each side of the is cut middle portion of the needle valve, with the valve housing bore 148 in connection. The channel 155 and the central anchor bore thus represent a pressure relief for an air gap which is arranged between the anchor and the core element. This prevents it from getting there

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hydraulic forces build up and the opening time of the valve influence.

The closing spring is by the ball element 136 against the Valve needle recess 147 compressed! to generate a closing force acting on the valve needle, which is caused by Turning the set screw 132 can be adjusted. No torsional forces whatsoever are generated during the adjustment because the pin 140 rotates on the ball member 136 and only one causes axial movement of the element. Any tendency to cause the part of the recoil spring to curl up sliding on the surface of the spherical element and thus a destruction of the torsional force component.

The fact that the closing spring contained in the armature 15Θ and in the Valve end is let in, the closing force is applied in front of the air gap and the lever arm is reduced over the eccentric force components could act. Shorter and narrower bearing surfaces can be found on the middle section of the valve pin Find use to balance the forces. By using a shorter triangular-shaped middle one Section with less bearing surface in connection with the valve needle and the armature becomes the mass of the moving Part of the injector significantly reduced. By reducing the mass of the moving part and by the increase in force caused by the enlargement of the

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Coil is generated, the opening time of the valve is reduced.

In operation the valve builds up when electricity is in the form of a Injection signal from connector 12 to connector pins 120 and thus the coil 116 is fed through the core element 128, the rear end cap 110, the main part 100 and the front end cap 106 has a magnetic field so that the soft magnetic material of the armature 156 across the air gap is attracted and abuts against a non-magnetic spacer 135 on the face of the core element. The spacer 135 is conducive to valve closing time by maintaining a minimal gap during energization. .When the tensile force exerted by the magnetic field exceeds the force of the closing spring, the valve needle is released from the The valve seat is lifted and fuel is dispensed through the valve seat interface and the metering orifice until the flow - flow to the connecting pins 120 is interrupted and the closing spring closes the valve sealingly again.

After assembly, the stroke of the valve and the air gap by turning the core element 128 and the closing force can be adjusted by turning the adjusting screw 132 * The two Adjustment processes complement each other to calibrate the static and dynamic fuel flow. A statement can take place via a sealing element 121.

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The setting of the static fuel flow rate through the valve will now be described with reference to FIG. There the static fuel flow rate Q of the injection valve 10 is shown as a function of the valve lift L. With small valve lifts in the range Λ, the throttling generated by the needle valve and the valve seat interface prevails, and the static fuel flow rate is independent of the metering opening size. In this range, the value J ^ Q / / \ L is a constant K, which is related to the increasing opening area between the interface of the needle valve and the valve seat.

In area C, where the stroke increases beyond the point at which the valve needle throttles the fuel flow, the size of the metering opening is the determining factor of the static fuel flow. In this area, the value ^ Q / > \ L is zero. Between the areas A and C there is a smaller area B in which the static fuel flow through the injection valve is essentially a function of the size of the metering opening, but also depends on the valve lift. In this area, the value ^ \ Q / j ^ L is much less than K and approaches the value of zero that exists in area C. The change in the static fuel flow when the valve lift changes is dependent on the ratio of the changing boundary surface area and the area of the metering opening.

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By adjusting the valve lift in this range, a relatively easy to control vote for calibrating the static fuel flow of an already assembled Injection valve to a special value possible. It has been found that this procedure produces optimal results delivers when the tuning range S% of the static fuel flow rate for a change in valve lift of 25 µm amounts to. The adjustment thread on the core element 128 is selected in a suitable manner to allow for controllable changes in the stroke of this Order of magnitude.

After the static flow has been calibrated, a dynamic calibration is performed to determine the clamping force to match the air gap that was changed during the static calibration and the dynamic Receive response to discontinue. In Figure 5 is the dynamic Fuel flow rate shown as a function of the pulse length. The dashed line 0 shows an ideal valve, a static flow rate [gradient] of 600 cm / min and whose characteristic curve runs through the zero point.

The opening and closing times of an actual valve are limited, however, so that the actual dynamic characteristic is reproduced, for example, by a line E running parallel to the ideal line to the right. The less "ideal" and slow the valve operates, the more is really ^s dynamic lines of the line D to the right "A critical operation at higher engine speeds

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requires a maximum injection quantity, while that for the The time available for the injection process decreases · Valves with high flow rates and steep dynamic characteristics are required to meet these requirements, but cause very small pulse lengths for the minimum Find injection quantities use. The sooner the valve can be calibrated linearly to the ideal case, the more advantageous is this for the system.

With these goals in mind, the dynamic calibration is carried out using the minimum flow rate of the valve at point G is taken up, which is a certain safety factor below that injected at idle Minimum amount or the point F includes. The closing force is then adjusted so that the shift of line E compared to the ideal response behavior at line D on a minimum is brought.

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Claims (5)

THE. DENDIX CORPORATION Executive Offices 2942853 Bendix Center Guuthfield, Michigan 4BÜ7S UjA
U-50d7 19th October 1979 Claims Electromagnetic fuel injection valve with a valve arrangement, which comprises a valve housing and a valve element with an armature part, the valve element in the valve housing is movable between a closed position and an open position to supply pressurized fuel from an inlet port in the housing to an outlet port to dose in the housing, stator devices which can be connected to an electrical power source and which are located in a injector housing are included to the valve element by attracting the armature part by means of a magnetic field when carrying current the stator means to move to the open position, and means to move the valve element into the closed position after interruption of the current flow to the stator devices, characterized in that that the stator devices comprise a bobbin which is arranged in the injection valve housing, as well as sealing devices, which is elastic between a portion of the bobbin and a portion of the injection valve housing are compressed to produce the pressurized fuel 030020/0620 ^{/ 2} to seal within the injection valve housing, the bobbin and the injection valve housing being different have volumetric temperature expansion coefficients, so that the compression of the sealing devices increases, when the temperature drops. 2. Injection valve according to claim 1, characterized in that the bobbin includes a central bore with a cylindrical recess at each end, each being cylindrical The recess forms a cylindrical outer surface and wherein the injection valve housing section has a cylindrical inner surface within each cylindrical recess of the bobbin, and that the sealing means have an O-ring made of elastomeric material, located in each recess and compressed between the cylindrical outer surface and the cylindrical inner surface is so that each O-ring when the temperature drops one increased compression between the last-mentioned surfaces. 3. Injection valve according to claim 2, characterized in that the injection valve housing comprises a tubular main part, at the ends of which a front and rear end cap are attached, and that the stator means between the End caps are arranged in an inner chamber of the main part. 030020/0620 ^{/ 3} 4. Injection valve according to claim 3, characterized in that the cylindrical inner surface as a projection of the end caps
is trained. 5. Injection valve according to claim 4, characterized in that the cylindrical inner surface of the rear end cap is formed by a Btangenförmices core element by a
central hole of the rear end cap is guided and
extends into the bobbin bore. 030020/0620