EP3655641B1 - Injector for injecting fuel - Google Patents

Description

The present invention relates to an injector for injecting fuel.

In internal combustion engines such as diesel engines or gasoline engines, fuel is usually injected into a combustion chamber in a certain amount and for a certain period of time via an injector. Due to the very short injection times, which are in the microsecond range, it is necessary to open or close the outlet opening of the injector at a very high frequency.

An injector typically has a nozzle needle (also: injector needle), which allows high-pressure fuel to escape to the outside when an outlet hole in the injector is released. In interaction with this outlet opening, this nozzle needle acts like a plug, which allows the fuel to escape when it is lifted. It is therefore necessary to lift this needle at relatively short intervals and to allow it to slide back into the outlet opening after a short time. Hydraulic ones can be used Servo valves are used to trigger this movement.

Such valves, in turn, are controlled with the help of an electromagnet.

document DE 10 2005 052 252 A1 shows a fuel injector. The fuel injector is delimited from the outside by a valve housing comprising several components. At least one of the components forming the valve housing is formed using metal injection molding, in particular at least one of the components, the connecting piece, the magnet pot and the nozzle body.

Due to the high injection pressures of over 2500 bar, it is not possible to control or move the nozzle needle directly using a solenoid valve. The force required to open and close the nozzle needle would be too great, so that such a process could only be implemented with the help of very large electromagnets. However, such a construction is not possible due to the limited installation space available in an engine. Typically, instead of direct control, so-called servo valves are used, which control the nozzle needle and are themselves controlled via an electromagnetic valve. In this case, in a control chamber that interacts with the nozzle needle, a pressure level is built up with the help of the fuel available under high pressure, which acts on the nozzle needle in the closing direction. This control chamber is typically connected to the high-pressure area of the fuel via an inlet throttle. This control room also has a small, closable outlet throttle from which the fuel can escape. If he does this, the pressure in the control chamber and the closing force acting on the nozzle needle are reduced because the high-pressure fuel in the control chamber can flow away. This causes the nozzle needle to move, which opens the outlet opening at the injector tip. In order to be able to control the movement of the nozzle needle, the outlet throttle of the valve is either closed or opened using an anchor element.

The valve itself can be brought into the desired position using an electromagnet. If the electromagnet is in a de-energized state, a certain spring force is required which presses the armature element against the drain throttle (=opening of the valve). When the electromagnet is energized, the anchor element is attracted against the spring force exerted by the spring element, so that the spring is compressed and releases the outlet throttle of the valve. It should be noted that the The magnetic circuit of the electromagnet represents a significant cost component of the entire injector, as this accounts for approximately 42% of the total injector manufacturing costs.

It is therefore the aim of the present invention to reduce the manufacturing costs while maintaining the same or reduced dimensions of the injector, especially with regard to the costs incurred for the magnetic circuit or the electromagnet.

This is achieved with the help of the injector according to the invention, which has all the features of claim 1. Accordingly, the injector according to the invention for injecting fuel comprises an injector housing for accommodating at least one injector component and an electromagnet for controlling a valve for opening and closing the injector, the electromagnet having a coil winding and a magnet body. The injector according to the invention is characterized in that the injector housing is formed in one piece with the magnet body.

By providing the injector housing and the magnet body of the electromagnet in one piece, the number of components and the complexity are reduced, which in turn leads to a reduction in the manufacturing costs of the injector. From the prior art, only injectors are known that have a separate magnet assembly that is designed independently of the injector housing and is also manufactured independently of it. The situation is that the injector housing in the assembled state represents more of a disturbance in the magnetic circuit and also brings with it the problem that only small pole surfaces are provided due to the reduced diameter available when the injector housing and a separate magnet assembly are provided at the same time can be made, which entails the need to use very high-quality and expensive materials for the magnetic core.

This problem is avoided or solved with the help of the present invention, since the injector housing is formed in one piece with the magnet body. With such an implementation, the manufacturing costs for the solenoid valve, which includes the electromagnet and an armature element, can be reduced by approximately 85% compared to the implementations known from the prior art.

According to a development of the present invention, the coil winding is mounted directly on the injector housing, preferably the coil winding is wound around an outer peripheral surface of the injector housing.

By mounting the magnetic coil directly on the injector housing, a larger pole area can be created, so that a less high-quality material can be used for the magnetic core than for injectors known in the prior art. This leads to considerable savings effects.

According to the present invention, the magnetic body has an inner magnetic pole, which is provided within the coil winding, and an outer magnetic pole, which is provided outside the coil winding, wherein the injector housing is integrally connected to the inner magnetic pole and/or the outer magnetic pole.

According to the invention, the injector housing is formed in one piece with the inner magnetic pole or with the outer magnetic pole. The invention further includes that both the inner magnetic pole and the outer magnetic pole are formed in one piece with the injector housing.

According to a preferred variant of the invention, the injector housing comprises or consists of a Cr-Mo alloyed tempered steel, the Cr-Mo alloyed tempered steel preferably being 50CrMo4.

If the injector housing is made of tempered steel with a chrome-molybdenum alloy, a good ratio of high-pressure swelling strength is achieved and the desired magnetic properties. Tempered 50CrMo4 represents the optimum in terms of high pressure threshold strength and magnetic properties. In particular, it is preferable to produce the steel with a particularly high level of purity.

According to the invention it is provided that the first injector housing comprises a first injector housing section and a second injector housing section, and one of the two injector housing sections is connected in one piece to the magnet body or both injector housing sections are connected in one piece to the magnet body.

If you divide the injector housing into several sections, assembling and assembling the injector is easier.

Furthermore, it can be provided that the coil winding of the electromagnet is mounted directly on the first injector housing section and is preferably wound around an outer peripheral surface of the first injector housing section. The coil winding can come into direct contact with the first injector housing section.

According to a further optional development of the invention, the injector further comprises a valve for exerting a variable pressure on an injector needle, the second injector housing section adjoining the valve.

This valve has an outlet throttle which can be closed using an anchor element movably mounted in the injector. When the valve is closed, such great pressure is exerted on the injector needle that it closes the injector outlet. However, if the drain throttle opens by lifting the anchor element, the pressure level drops and allows the injector needle to be raised from its closed position.

Furthermore, it can be provided that the second injector housing section supports the anchor element for selectively closing the outlet throttle.

In addition, according to the invention it can be provided that the second injector housing section is connected in one piece to a part of the magnet body provided outside the coil winding. It is advantageous if the part of the magnet body provided outside the coil winding directly adjoins the coil winding.

According to the invention, the first injector housing section is connected in one piece to a part of the magnet body provided within the coil winding.

According to the invention, the injector further comprises an anchor element for selectively closing a valve opening, the anchor element being movable by the electromagnet.

It is thus provided that the anchor element is moved into a position in which the electromagnet is energized, in which the anchor element forms a magnetic circuit together with an inner magnetic pole and an outer magnetic pole of the magnetic body.

This creates a magnetic flux via the injector housing and the anchor element, which is also called an anchor in technical jargon.

According to the invention, in this position, which is achieved when the electromagnet is energized, the anchor element touches both the inner magnet pole and the outer magnet pole, with the valve opening preferably being in an open position in this position.

According to a further modification of the present invention, the anchor element comprises or consists of a steel tempered with chromium and molybdenum this one. It can also be provided that the anchor element consists of 50CrMo4.

According to the invention, the injector housing is an outer injector housing. It therefore represents, at least in sections, the external termination of the injector.

Furthermore, it is provided that the injector housing, the first injector housing section and preferably the second injector housing section have a line channel for flowing or guiding fuel from one or more bores distributed around the circumference. This line channel is located in the injector housing itself. This channel can preferably be introduced into the injector housing, for example using a hole or a similar method.

The invention further comprises an internal combustion engine with an injector which is designed according to one of the variants described above.

Fig.1:

einen Teilquerschnitt eines herkömmlichen Injektors,

Fig. 2:

einen Ausschnitt der Fig. 1 in vergrößerter Darstellung zum Erläutern der Funktionsweise eines Injektors,

Fig. 3:

einen Querschnitt eines erfindungsgemäßen Injektors, und

Fig. 4:

einen Ausschnitt aus Fig. 3 in vergrößerter Darstellung zum Erläutern der Unterschiedsmerkmale gegenüber dem Stand der Technik.

Further features, details and advantages of the present invention will become apparent from the following description of the figures. Show:

Fig.1:

a partial cross section of a conventional injector,

Fig. 2:

a section of the Fig. 1 in an enlarged view to explain how an injector works,

Fig. 3:

a cross section of an injector according to the invention, and

Fig. 4:

a section Fig. 3 in an enlarged view to explain the differences compared to the prior art.

Fig. 1 shows a partial sectional view of an injector from the prior art. You can see the injector 1, which has a housing 2 in which several injector components are arranged. Essential to the function of the injector 1 are the injector needle 5, the valve 4, the anchor element 6 and the electromagnet 3, which has a coil winding 31, an inner magnetic pole 32 and an outer magnetic pole 33. In addition, a recess is provided in the inner magnetic pole 32 for arranging the spring 8, which presses the anchor element 6 in the direction of the valve 4 in order to close the outlet throttle of the valve 4 in a fluid-tight manner when the electromagnet is in a de-energized state.

If you activate the electromagnet 3, it pulls the anchor element 6 away from the valve 4 with the help of magnetic force, so that high-pressure fuel can flow out of a control chamber that can be closed by the valve 4. Since this reduces the pressure in the control chamber that acts on the injector needle 5, it can slide out of a closed position and enables fuel to be released from the injector 1. However, if the electromagnet 3 is put into a de-energized state, this can be done Armature element 6 acting magnetic force, so that the spring element 8 presses the anchor element 6 onto the outlet opening of the valve 4 and seals the control chamber. This causes the pressure acting on the injector needle 5 to increase, forcing it back into its closed position. This means that fuel no longer flows out of the outlet opening of the injector 1.

Fig. 2 shows an enlarged view in the lower region of the anchor element 6 in a closed state of the valve 4. An outlet throttle 41 can be seen, which represents an outlet for fuel stored under high pressure in a control chamber 44. If the anchor element 6 is not located on the sealing seat 45 of the valve 4, the fuel absorbed under high pressure from the control chamber 44 can flow out via a passage space 42 into a low-pressure area. The valve 4 can also be provided with a movable valve insert 43, with the help of which the force acting on the injector needle 5 can be reduced or built up particularly quickly.

Fig. 3 shows a cross section along the longitudinal direction of an injector according to the invention. A line channel 7 for supplying fuel can be seen, which is arranged in a first housing section 21 of the injector 1. At the same time, the injector housing 2 also represents a magnetic body of the electromagnet 3. In the present figure, the injector housing 2 is divided into a first injector housing section 21 and a second injector housing section 22. The first injector housing section 21 also represents an outer housing of the injector 1. Furthermore, the first injector housing section 21 is also an inner magnetic pole of the electromagnet 3. The second injector housing section 22 represents an outer magnetic pole of the electromagnet 3. The inner magnetic pole is separated from the outer magnetic pole by a coil winding 30 Furthermore, the first injector housing section 21 and the second injector housing section 22 are characterized in that they each have a channel in their bodies for guiding fuel.

Fig. 4 shows an enlarged section Fig. 3 , which shows the area around the electromagnet 3. You can see the coil winding 31, which is wound around an outer peripheral section of the first injector housing section 21 and thus also represents the inner magnetic pole of the electromagnet 3. A magnetic outer pole 33 is also provided on the outside around the coil winding 31, which also represents a second injector housing section 22.

A channel 7 for carrying fuel or another fluid runs through the first injector housing section 21 and also through the second injector housing section 22.

In the in Fig. 4 In the state shown, the coil winding 31 is shown in an energized state, since the armature element 6 is lifted from its closed position from the outlet throttle of the valve. In order to bring the anchor element 6 into such a position, it is necessary to overcome the closing force exerted with the help of the spring 8, which is achieved by the electromagnet 3.

Advantageously, in the configuration shown, a magnetic flux or a magnetic circuit is formed which runs from the inner magnetic pole 32 via the anchor element 6 to the outer magnetic pole 33. Accordingly, a magnetic flux arises via the injector housing 2 and the anchor element 6 (also: immersion anchor).

With an injector 1 formed in this way, the manufacturing costs for the solenoid valve can be reduced by approximately 85%. Another advantage here is the smaller number of components, which can be achieved due to the magnetic components no longer being required separately.

Claims (9)

1. Injector (1) for injecting fuel, comprising:

   an injector outer housing (2) for accommodating at least one injector component, wherein the injector outer housing (2) comprises a first injector housing portion (21) and a second injector housing portion (22),

   an electromagnet (3) for controlling a valve (4) for opening and closing the injector (1), and

   an armature element (6) for selectively closing a valve opening (41), wherein the armature element (6) is movable by the electromagnet (3), wherein

   the electromagnet (3) comprises a coil winding (31) and a magnetic body (32, 33) which has an inner magnetic pole (32) provided inside the coil winding (31), and an outer magnetic pole (33) provided outside the coil winding (31), wherein the first injector housing portion (21) is formed integrally with the inner magnetic pole (32) and comprises a line channel (7) for supplying fuel,

   wherein the armature element (6) is moved, in a powered state of the electromagnet (3), to a position in which the armature element (6) forms a magnetic circuit together with an inner magnetic pole (32) and an outer magnetic pole (33) of the magnetic body (32, 33), and

   the inner magnetic pole (32) is separated from the outer magnetic pole (33) by a coil winding,

   characterised in that

   the armature element (6) contacts both the inner magnetic pole (32) and the outer magnetic pole (33) in the powered state of the electromagnet (3).
2. Injector (1) according to any one of the preceding claims, wherein
   the first injector housing portion (21) is further integrally connected to the outer magnetic pole (33).
3. Injector (1) according to any one of the preceding claims, wherein the first injector housing portion (21) comprises or consists of a Cr-Mo alloyed quenched and tempered steel, wherein preferably the Cr-Mo alloyed quenched and tempered steel is 50CrMo4.
4. Injector (1) according to any one of the preceding claims, wherein the coil winding (31) of the electromagnet (3) is mounted directly to the first injector housing portion (21), preferably wound around an outer peripheral surface of the first injector housing portion (21).
5. Injector (1) according to any one of the preceding claims, further comprising a valve (4) for exerting a variable pressure on an injector needle (5), wherein the second injector housing portion (22) is adjacent to the valve (4).
6. Injector (1) according to any one of the preceding claims, wherein the second injector housing portion (22) is integrally connected to a part of the magnetic body (33) provided outside the coil winding (31).
7. Injector (1) according to any one of the preceding claims, wherein in the position in which the armature element (6) contacts both the inner magnetic pole (32) and the outer magnetic pole (33), the valve opening is in an open position.
8. Injector (1) according to any one of the preceding claims, wherein the second injector housing portion comprises a line channel (7) for the flow of fuel.
9. Internal combustion engine comprising an injector (1) according to any one of the preceding claims.

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