EP2064437B1 - Injector for injecting fuel - Google Patents

Abstract

The invention relates to an injector for injecting fuel into a combustion chamber of an internal combustion engine, comprising an injection valve member (1) which opens or closes off at least one injection opening. The injection valve member (1) is activated by means of a magnet-actuable control valve (3). The magnet-actuated control valve (3) comprises an armature (37) which has a central bore (41) in which an armature pin (19) is held in a movable fashion. The armature (37) can move between an upper (49) and a lower (47) stop on the armature pin (19). When the control valve (3) is closed, the armature (37) is held by the spring force of a spring element (61) against its lower stop (47).

Description

The invention relates to an injector for injecting fuel into a combustion chamber of an internal combustion engine according to the preamble of claim 1.

For introducing fuel into combustion chambers of internal combustion engines often injection systems are used. These generally comprise, for each combustion chamber, an injector via which fuel is injected under high pressure into the combustion chamber. For this purpose, the injector generally comprises an injection valve member which releases or closes at least one injection opening. The injection valve member is generally controlled via a control valve. The control valve may be magnetically actuated or driven by a piezoelectric actuator. Magnetically operated control valves generally include a solenoid accommodated in a magnetic core and an armature movably mounted on an armature bolt to minimize the influence of the armature vibrations. Usually, the anchor is placed by means of a spring element in the direction of the coil against a stop.

The anchor bolt is connected to a closing element which is placed in a seat for closing the control valve. The force required for this purpose is applied via a spring element on the anchor bolt. To open the control valve, the coil is energized, so that forms a magnetic field and attracts the anchor. About the stop of the anchor this lifts the anchor bolt with the closing element from its seat. Here, the anchor must overcome the restoring force of the spring element, with the anchor bolt is placed with the closing element in his seat. In addition, the anchor is usually designed as a flat armature, whereby the magnetic circuit with larger the residual air gap and stroke loses power. The dynamics of the magnetic actuator comprising the solenoid and the armature are limited.

A fuel injector with a solenoid-operated control valve that controls an injection valve member for injecting fuel into the combustion chamber of an internal combustion engine is off DE 197 08 104 A1 known. The control valve comprises an armature having a central bore, with which the armature is movably guided on an anchor bolt. The armature is moved between the open position and the closed position of the control valve on the anchor bolt, wherein the anchor bolt is guided in a housing-fixed sleeve. A lower stop limits only a compensating movement of the armature when closing the control valve, so that the armature is in its initial position with the control valve closed again in a formed on the anchor bolt upper stop. As soon as the magnetic force starts, the armature acts directly on the upper stop fixed on the anchor bolt.

Another solenoid-operated control valve for a fuel injector goes out WO 02/092991 A1 out. In this case, the armature is guided axially on the anchor bolt between a stop fixed to the anchor bolt and an overstroke stop. The overstroke stop represents a momentary stop position during the closing process, wherein the stationary stop coincides in the closed position with the upper stop on the anchor bolt.

At the EP 1 382 839 A1 and DE 101 31 125 A1 known solenoid-operated control valves, the armature is firmly connected to the anchor bolt.

Disclosure of the invention Advantages of the invention

An inventively designed injector for injecting fuel into a combustion chamber of an internal combustion engine comprises an injection valve member which releases or closes at least one opening. The injection valve member is driven by a solenoid-operated control valve. The solenoid operated control valve includes an armature having a central bore in which an anchor bolt is movably received, the armature being movable between upper and lower stops on the anchor bolt. According to the invention, the armature is held by the spring force of a spring element against its lower stop when the control valve is closed.

Advantage over the control valves known from the prior art, in which the armature is held against the upper stop, is that even a small magnetic force is sufficient to move the armature in motion. The already moving armature strikes against the upper stop and thus opens the control valve with high momentum. In addition, the magnetic field has built up at this time and provides another contribution in addition to the impulse to accelerate the anchor bolt. For this reason, reach the anchor and the anchor bolt much faster than in the known from the prior art injectors the top stop. The force additionally acting on the armature bolt by the impulse makes it possible to increase the spring force of the spring element with which the armature bolt engages the locking element in its seat. This results in a shorter closing time. The flight time, i. However, the time during which the armature is moved in the direction of the magnet is not extended.

The anchor is dazn connected to an anchor sleeve on which a collar is formed, against which the spring element, with which the armature is held at its lower stop, is set. An advantage of the anchor sleeve is that the control valve designed according to the invention can be used without much effort in a known from the prior art fuel injector, wherein the armature is set with the control valve closed at its upper stop. The anchor sleeve is connected to the armature, for example non-positively or positively or may also be integrally formed with the armature. By the non-positive or positive connection of the anchor sleeve with the anchor or the integral formation of the anchor sleeve with the armature is avoided that the anchor sleeve can move independently of the anchor. A fixation on the anchor is guaranteed.

To place the anchor against the lower stop, the anchor bolt preferably comprises a shoulder, wherein the spring element, with which the armature is held against its lower stop, placed with one side against the shoulder and the other side against the collar on the anchor sleeve is. The spring element is preferably designed as a compression spring coil spring.

To avoid tilting of the armature on the anchor bolt, a sleeve-shaped extension is preferably formed on the armature, in which the anchor bolt is guided. In one embodiment, a circumferentially extending rib is formed on the sleeve-shaped extension, with which the anchor sleeve is connected.

The anchor bolt is guided in a sleeve which is fixed with a flange-shaped extension in the injector housing. For this purpose, the flange-shaped extension is placed against an adjusting ring and fixed with a threaded sleeve. The adjusting ring rests on a valve piece which is accommodated in the injector housing and bears against a shoulder in the injector housing. Furthermore, however, it is also possible that the flange-shaped extension, e.g. rests directly on a shoulder on the injector housing or that the shim, against which the flange-shaped extension is placed, rests on the shoulder on the injector housing. Any further, known in the art way to fix the sleeve on the injector, is possible.

When the control valve is open, the armature is placed against its upper stop on the anchor bolt. The upper stop is e.g. formed by a ring which is received in a groove in the anchor bolt. The material of the ring is preferably chosen so that the ring is not deformed by the anchor abutting it. Suitable material for the ring is e.g. stainless steel, preferably 1.4305 steel. The anchor is preferably made of 100Cr6 steel. The anchor bolt is preferably made of one of the steels 1.4305 or 100Cr6.

Another advantage of the inventively embodied fuel injector is that the dynamics of the magnetic actuator can be kept constant with reduced output power. Usually in fuel injectors, such as those used in high-pressure storage injection systems, current-controlled output stages are used. The control is carried out in a boost phase and a holding phase. The boost phase ensures a quick opening of the anchor bolt and requires a lot of energy. The inventive Fuel injector allows same opening times with lower boost voltage and thus leads to cost savings on the power amplifier.

Brief description of the drawings

An embodiment of the invention is illustrated in the single drawing and explained in more detail in the following description.

The single FIGURE shows an inventively designed control valve of a fuel injector.

Embodiment of the invention

In the single figure, a section of a fuel injector is shown with a erfmdungsgemäß formed control valve.

In an inventively designed injector for injecting fuel into a combustion chamber of an internal combustion engine, an injection valve member 1, which releases or closes at least one injection port not shown here, is controlled via a control valve 3. For this purpose, the control valve 3 is a compound of a control chamber 5, which is bounded by an end face 7 of the injection valve member 1, in a valve chamber 9 which is connected to a fuel return 10, free or closes them. For this purpose, a closing element 11 is placed in a seat 13 or lifted from this, to close a channel 15 through which the control chamber 5 is connected to the valve chamber 9. In the channel 15, a throttle element 17 is received.

In addition to the embodiment in which the end face 7 of the injection valve member 1 limits the control chamber 5, it is also possible that an end face of a control piston delimits the control chamber 5. In this case, the control piston is either directly connected to the injection valve member or the control piston serves as a booster piston, wherein the control piston and the injection valve each with an end face define a booster chamber and is increased by a movement of the control piston in the booster chamber, the pressure in the booster chamber, whereby a increased pressure acts on the injection valve member and the injection valve member is placed in its seat to close the at least one injection port. When the control piston is lifted out of the control chamber, the volume in the booster chamber increases, so that the pressure in it decreases and a lower pressure acts on the injection valve member. The injection valve member is out of its seat lifted and releases the at least one injection port for injecting fuel into the combustion chamber of the internal combustion engine.

The closing element 11 is placed in its seat 13 by means of an anchor bolt 19. The force required for this purpose is applied by a spring element 21 on the anchor bolt 19. The spring element 21 is preferably designed as a compression spring coil spring. With one side, the spring element 21 acts on a shoulder 23 on the anchor bolt 19. With the other side, the spring element 21 acts against a housing cover 25. In order to adjust the required spring force of the spring element 21, a shim 27 is received between the housing cover 25 and the spring element 21 , Due to the thickness of the dial 27, the bias of the spring element 21 is adjusted. So that the spring element 21 does not slip on the anchor bolt 19, a pin 29 is formed on the anchor bolt 19, which is enclosed by the spring element 21.

The spring element 21 is surrounded by a magnetic core 31, in which a coil 33 is accommodated for generating a magnetic field. By the magnetic field generated by the coil 33, an anchor plate 35 of an armature 37 is attracted. The armature 37 further comprises a sleeve-shaped extension 39, which is connected to the anchor plate 35. The sleeve-shaped extension 39 and the anchor plate 35 passes through a central bore 41, in which the anchor bolt 19 is guided. The diameter of the central bore 41 in the armature 37 is chosen so that the armature 37 is movable on the anchor bolt 19 without much effort. At the same time, the diameter of the central bore 41 must not be so great that the armature 37 can tilt on the anchor bolt 19.

In the embodiment shown here, the anchor bolt 19 is guided in a sleeve 42 which is fixed with a flange-shaped extension 43 on the injector 44. For this purpose, the flange-shaped extension is provided against an adjusting ring 45 which rests on a valve member 46 on the injector 44. The valve piece rests on a shoulder 48 on the injector housing 44. The valve member 46, the dial 45 and the flange-shaped extension 43 formed on the sleeve 42 are fixed with a threaded sleeve 50 in the injector housing. In addition to the embodiment shown here, however, the sleeve 42 can also be fixed in the injector housing 44 in any other manner known to those skilled in the art. For example, it is possible that the flange-shaped extension 43 or the adjusting ring 45 rest on a shoulder on the injector housing 44, or that an external thread is provided on the flange-shaped enlargement 43 and the sleeve 42 is screwed into the injector housing 44 with the flange-shaped enlargement.

An upper end surface of the sleeve 42, which faces the sleeve-shaped extension 39 of the armature 37, serves as a lower stop 47. By the lower stop 47, the movement of the armature 37 is stopped on the anchor bolt 19. On the armature plate 35 facing side of the anchor bolt 19, an upper stop 49 is formed. The upper stop 49 is an armature plate 35 facing end face of a ring member 51 which is received in a groove 53 in the anchor bolt 19. The armature 37 is movable between the upper stopper 49 and the lower stopper 47.

On the sleeve-shaped extension 39 of the armature 37, a circumferentially extending rib 55 is formed. An anchor sleeve 57 is connected to the circumferentially extending rib 55. The connection of the rib 55 with the anchor sleeve 57 can be done non-positively or positively. It is also possible that the armature 37 and the anchor sleeve 57 are integrally formed. The attachment of the anchor sleeve 57 to the rib 55 may e.g. by welding, soldering or gluing. Furthermore, it is also possible that the anchor sleeve 57 is screwed onto the rib 55. Any other, known to those skilled fastening is possible. Thus, e.g. An attachment with screws or rivets may be possible.

At the anchor sleeve 57, a collar 59 is formed. The federal government 59 points inwards. At the collar 59, a spring element 61 is supported, which encloses the sleeve 42 and on the other hand supported on a shoulder 63 which is formed on the sleeve 42. The shoulder 63 is formed on the armature 37 facing the side of the sleeve 42. The spring element 61 is thus positioned between the sleeve 42 and the anchor sleeve 57. The spring element 61 is preferably designed as a compression spring coil spring. By the spring force of the spring element 61, the armature 37 is pulled against the sleeve 42 and thus placed on the lower stop 47. The spring force of the spring element 61 is chosen so that when not energized coil 33 of the armature 37 is held straight on the lower stop 47.

Not according to the invention it is also possible that e.g. designed as a compression spring spring element acts on the anchor plate 35. Here, the spring element surrounds the anchor bolt 19 and the spring element 21, which acts on the anchor bolt 19. The spring element acting on the anchor plate 35 is then against one side against the anchor plate 35 and on the other side e.g. placed against the housing cover 25.

When the control valve 3 is closed, the closing element 11, which is spherical in this case, is in its seat 13. As a result, the channel 15 is closed. Since the control chamber 5 is connected via a throttle element 65 with a fuel inlet, located in the control chamber 5 under system pressure standing fuel. The pressure force of under system pressure standing fuel acts on the end face 7 of the injection valve member 1 and puts this in his seat. The at least one injection port is closed. So that the closing element 11 is not lifted out of its seat 13 by the pressure force of the fuel under system pressure, it is necessary for the closing element 11 to be placed in its seat 13 with a sufficiently large force. This force is applied by the spring element 21 on the anchor bolt 19, with which the closing element 11 is placed in its seat 13. Since the coil 33 is not energized when the control valve 3 is closed and thus no magnetic field is formed, the armature 27 is placed by the spring element 61 at its lower stop 47. To start the injection process, the coil 33 is energized. It forms a magnetic field. With the magnetic field beginning, the armature 37 is first accelerated along the anchor bolt 19 in the direction of the upper stop 49. The armature 37 abuts the upper stop 49, whereby a pulse on the upper stop 49 and thus the anchor bolt 19 acts. The anchor bolt 19 is accelerated against the spring force of the spring element 21. At the same time acts on the armature plate 35, the now fully formed magnetic field of the coil 33. The armature 37 is further moved in the direction of the coil 33. Since the armature is placed against the upper stop 49, the anchor bolt is also moved in the same direction. The closing element 11 rises from its seat 13. The standing under system pressure fuel from the control chamber 5 flows through the channel 15 into the valve chamber 9 and from there into the fuel return. The pressure in the control chamber 5 decreases. For this reason, a lower pressure force acts on the end face 7 of the Einspitzventilgliedes 1 and the injection valve member 1 rises from its seat. The injection process begins.

To end the injection process, the energization of the coil 33 is stopped. The magnetic field is canceled. By the spring force of the spring element 21 of the anchor bolt 19 is moved in the direction of the control chamber 5. As a result, the closing element 11 is placed in its seat 13 and thus closes the channel 15. By flowing over the throttle element 65 under system pressure fuel is in the control room 5 system again. This acts on the end face 7 of the injection valve member 1 and presses this into its seat. The at least one injection opening is closed. After the closure member 11 is placed in its seat 13 and so the movement of the anchor bolt 19 is completed, the spring member 61 acts on the collar 59 on the anchor sleeve 57 and thus pulls the armature 37 against its lower stop 47. The anchor is back in his starting position.

Claims (6)

1. Injector for injecting fuel into a combustion chamber of an internal combustion engine, comprising an injection valve member (1) which opens up or closes off at least one injection opening, with the injection valve member (1) being actuated by means of a magnet-actuable control valve (3) and with the magnet-actuable control valve (3) comprising an armature (37) which has a central bore (41) in which is movably held an armature pin (19), with the armature pin (19) setting a closing element (11) into its seat (13) by means of the force of a spring element (21), with the armature (37) being movable between an upper stop (49) and a lower stop (47) on the armature pin (19), with the armature pin (19) being guided in a sleeve (42), and with the armature (37) being set against its upper stop (49) on the armature pin (19) when the control valve (3) is open, characterized in that the armature (37) is connected to an armature sleeve (57) on which is formed a collar (59) on which a spring element (61) engages, and in that when the control valve (3) is closed, the armature (37) is pulled against the sleeve (42) by the spring force of the spring element (61) and is thereby held against its lower stop (47) which is formed on the sleeve (42).
2. Injector according to Claim 1, characterized in that the armature sleeve (57) is connected to the armature (37) in a non-positively or positively locking manner or is formed in one piece with the armature (37).
3. Injector according to Claim 2, characterized in that the sleeve (42) comprises a shoulder (63) and the spring element (61) engages with one side on the shoulder (63) and with the other side on the collar (59) on the armature sleeve (57).
4. Injector according to Claim 4, characterized in that a sleeve-shaped projection (39), in which the armature pin (19) is guided, is formed on the armature (37).
5. Injector according to Claim 4, characterized in that a rib (55) which runs in the circumferential direction and to which the armature sleeve (57) is connected is formed on the sleeve-shaped projection (39) of the armature (37).
6. Injector according to Claim 1, characterized in that the upper stop (49) is formed by an annular element (51) which is held in a groove (53) of the armature pin (19).

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