DE2210213A1 - ELECTROMAGNETIC FUEL INJECTION VALVE FOR COMBUSTION MACHINES - Google Patents

Description

February 10, 1972 Ks / Kb

Attachment to

Patent and

Utility model auxiliary application

ROBERT BOSCH GMBH, 7 Stuttgart 1

Electromagnetically actuated fuel injection valve for internal combustion engines

The invention relates to an electromagnetic actuatable fuel injection valve for internal combustion engines, its valve needle guided in a bore in the valve housing with the armature of an electromagnet is connected and counteracts when the Elekti-omagneten is excited the force of a closing spring and counter to the direction of flow of the pumped under inlet pressure from a pressure source Fuel lifts from the valve seat and a pressure chamber adjacent to the valve seat with at least one Nozzle opening connects.

309838/0037

Robert Bosch GmbH R. Ks / Kb

Stuttgart

With such fuel injection valves (DT-PS 483 101, DT-OS 1 526 635) with valve needle opening inwards and when the injection valve is closed, a valve seat controlled by this always occurs due to the inlet pressure the pressure source generated hydraulic force that wants to keep the valve closed and proportional to the Inlet pressure and that corresponding to the valve seat diameter Area is. Because of the limited installation space on the motor, the size of the electromagnet and thus also his Force is limited, you are forced with these valves to reduce the valve seat diameter at high injection pressures to train small, but this has the disadvantage that the amount of fuel to be injected after the valve seat is strongly throttled, whereby a pressure loss already occurs before the fuel reaches the nozzle opening. Since the Valve seat diameter due to the required injection conditions is set within very narrow limits, and the magnetic force for the reasons mentioned above also results inevitably a strong limitation of the application possibilities such valves. For these reasons, the known direct-acting electromagnetically actuated fuel injection valves, in which the valve needle is directly coupled to the armature of the electromagnet, only to a limited extent Pressure range for fuel injection Diesel engines are used.

Another disadvantage of these valves is the dependence of the opening and closing times on the inlet pressure, because with With a constant switching time of the magnet, the opening movement of the valve needle is dependent on the level of the inlet pressure more or less delayed or their closing movement more or less accelerated, whereby each injected fuel quantity changes.

309838/0037

Robert Bosch GmbH R. Ks / Kb

Stuttgart

It is also known that in the case of the fuel injection valves described above with inwardly opening valve needle, the area acted upon by the inlet pressure on the valve needle in the opening direction increases when the electromagnet is energized and the valve needle has lifted from the valve seat. This additional area is covered by the valve seat when the injection valve is closed and depends on the seat diameter and the type of valve. In the case of valves with a so-called "pin nozzle" (DT-OS 1 526 635), there is essentially only one effective annular surface that is limited radially outward by the seat diameter and inward by the pin diameter of the valve needle. If this ring area is very narrow, the enlargement of the area after opening is small and hardly has any disadvantageous effect. However, if it is large in relation to the area corresponding to the valve seat diameter, or if the valve described above is one with hole nozzles controlled by the valve needle (see e.g. DT-PS 483 101), this additional area is relatively large. Then, the additional disadvantage occurs dp _t is expended in valve closing force ß is greater than required for opening. This disadvantage leads to a slow and delayed closing of the valve needle and promotes the so-called "sticking" of the armature, that is the well-known holding effect caused by residual magnetism after the electromagnet has been switched off.

The invention lisgt the object to avoid these power cables in the known electromagnetically actuated fuel injection valves of the aforementioned type and to develop a valve that possible - is <reitgeliend independent of the inlet pressure, so that even for high injection pressures (about 200 to 8üG bar) for diesel engines single set "can earth. 3O ₉₈

-4- 0783

Robert Bosch GmbH R. Ks / Kb

Stuttgart 2210213

This object is achieved in that the valve needle is coupled to a compensating piston which is coaxial with Valve needle and armature is sealingly guided in a guide bore of the valve housing, and its first end face Druckeritlastet and its second face from the inlet pressure applied and its cross-sectional area is so large that when the injection valve is closed, the opening hydraulic forces acting on the valve needle are the same or at least approximately the same are.

The hydraulic force mentioned at the beginning, which wants to keep the valve closed, can be completely cancel and so a static force balance achieve. Small excess forces may be desirable in order to to accelerate the opening or closing, so that in these cases only an approximate force balance is generated.

A particularly advantageous embodiment of the invention is such that the only connection between the pressure chamber and an inlet space facing the armature and delimited by the second end face of the compensating piston an inlet channel provided with a throttle point. The throttle point used in the feed channel causes a pressure drop, the one that occurs without this throttle and also acts in the opening direction when the valve is open counteracts hydraulic force. A complete or almost complete compensation of this additional force can be achieve in that the throttle point has a throttle cross-section through which when the injection valve is open Pressure in the pressure chamber is reduced so that the force acting in the pressure chamber on the valve needle in the opening direction is at least is approximately equal to the force acting in the same direction in the same space when the injection valve is closed, whereby In addition to static, dynamic force compensation is also achieved. 3 0 9 8 3 8/0 0 3 7

Π 7 ß 0

Stuttgart

It is advantageous if the guide diameter the cross-sectional area corresponding to the valve needle at least 10 times as large as the flow cross-section of the valve seat; because as a result, the pressure drop to be generated by the throttle point is at most a tenth of the inlet pressure.

A preferred embodiment of the invention is to ensure that no transverse forces impair the action of the compensating piston in such a way that the compensating piston is an extension of the valve needle and armature via a flexible connecting member is coupled to the valve needle and the diameter of the compensating piston is equal to or at least is approximately equal to the diameter of the valve seat.

The tuning of the fuel injection valve is thereby facilitates that the inflow channel runs essentially in the longitudinal axis of the valve needle and there in an expansion a replaceable screw part accommodates in which the throttle point is arranged, and that the guide bore for the compensating piston is arranged in an exchangeable guide bush, which is connected to a return line leading channel of the valve housing is firmly inserted.

An advantageous further development of the subject matter of the invention results from the fact that the compensating piston is arranged between the valve needle and armature, connected to the armature and over a kink-proof connecting link frictionally engaged with the valve needle is coupled, and that the cross-sectional area corresponding to the diameter of the compensating piston around the Diameter of the valve seat corresponding cross-sectional area is smaller than the guide diameter of the valve needle corresponding cross-sectional area, whereby, between compensating piston and valve needle only compressive forces in an advantageous manner

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Robert Bosch GmbH R. Ks / Kb

Stuttgart

are effective, which increases the functional reliability.

A static and dynamic force balance can be found in Another advantageous development of the subject matter of the invention can also be achieved in that the valve needle - in Seen flow direction - liquid-tight behind the valve seat with a guide pin in a hole on the Is guided on the combustion chamber-side end face of the valve housing, and that the compensating piston serves as a connecting link between the armature of the electromagnet and the valve needle, whose diameter is at least approximately equal to the diameter of the guide pin and the diameter of the valve seat is, wherein the guide pin advantageously has the shape of a hole nozzle tip and a blind hole, which to the Valve seat facing away from the end of the valve needle is closed towards the combustion chamber of the engine in a known manner Contains nozzle opening and at least one connecting bore to an annular channel controllable by the valve seat in the Has lateral surface of the guide pin.

Another development of the subject matter of the invention results in that the valve needle - seen in the direction of flow - a guide piston in front of the valve seat and behind the valve seat has a spray pin penetrating the nozzle opening, and that as a connecting member between the armature of the electromagnet and the valve needle, the compensating piston is used, the diameter of which is at least approximately equal to that Diameter of the valve seat, a preferred embodiment of this valve is that the spray pin Forms a narrow annular gap with the nozzle opening, which is only used for a subset of the amount to be injected during full load operation Amount of fuel is designed, and that the

309838/0037 - ⁷ -

Robert Bosch GmbH R. Ks / Kb

Stuttgart

Injection pin has at least one additional injection hole controllable after a pre-stroke for the full-load injection quantity or for a partial load injection quantity which is greater than the partial quantity that can be injected through the annular gap, so that the most favorable injection conditions in each case for a partial quantity to be injected and for the full-load injection quantity available. A preinjection quantity can also be achieved with this arrangement being controlled.

Six embodiments of the electromagnetically according to the invention actuatable fuel injectors are in the drawing and are described in more detail below. Show it:

Fig. 1 shows a simplified section through the first embodiment in the closed position of the Injector,

FIG. 2 shows a section like FIG. 1, but in the open position of the injector,

Fig. 3 is a section through the second example of the invention object,

3a shows an enlarged detail from Fig. 3 in the area of the valve seat,

FIG. K shows a section through the part essential to the invention in the area of the valve needle of the third exemplary embodiment,

5 shows a section through the essential part of the invention Part in the area of the valve needle and the compensating piston of the fourth embodiment,

6 shows a section through what is essential to the invention Part in the area of the valve needle and the compensating piston of the fifth embodiment and

7 shows a section corresponding to FIG. 6, but for the sixth embodiment.

309838/0037

Hobcrt Bosch GmbH K. Ks / Kb

Stuttgart

In one shown only schematically and therefore in one piece drawn valve housing 9 of the first embodiment, an electromagnetically actuated fuel injection valve 10 according to FIGS. 1 and 2, a valve needle 12 is guided with a guide part 13 in a housing bore 11, the Guide diameter is designated by D (see Fig. 2). The valve needle 12 has a valve cone l'l, which in the closed State (Fig. 1) of the fuel injection valve 10 on a Valve seat 15 rests and thus the fuel flow to Nozzle openings K) prevented. Since the one with D_. designated Diameter of the valve seat 15, which is equal to the diameter of the end 17 of the valve needle 12 facing the valve seat is smaller than the diameter D. of the guide part 13 of the valve needle 12, a pressure shoulder l8 is formed, which in the closed state of the injection valve 10 from Inlet pressure p "des from a pressure source I9 via an inlet line 21 supplied fuel is acted upon and one side of a pressure chamber adjacent to the valve seat I5 22 limited.

The pressure source I.9 and the associated components are generally known and therefore presented in a simplified manner. This pressure source I9 can, for example, be one from the engine be driven gear pump or piston pump, the delivery pressure of which by a pressure control valve 23 to the desired Inlet pressure, e.g. ρ = 200 bar or 4ü0bar, is maintained. To compensate for pressure fluctuations «" ** ·), the pressure control valve 23 can be combined with a pressure accumulator, the structure of which is known as tier of the pressure regulating valve 23 is and is therefore not shown in more detail.

The fuel flowing in via the feed line 21 flows around it an electromagnet en 2p, the winding 26 of which is cooled

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Robort Bosch GmbH R. Ks / Kb

Stuttgart

is, and passes through a channel 27 into an inlet space 28. This inlet space 28 is connected to the pressure chamber 22 by an inflow channel 29 which runs essentially in the longitudinal axis of the valve needle 12 and there has a throttle point Jl with a throttle cross-section F _n , which 1 and 2 as a throttle bore in the wall of the valve needle 12 is shown.

The inlet pressure p "present in the inlet space 28 is applied on the one hand an end face 32 of the valve needle 12 and on the other hand, an anchor 331 of at least, as shown, is surrounded on two sides by the fuel at the same time, so that no: ί η opening direction of the valve acting on the armature 33 excess hydraulic force is effective. The armature 33 is guided with close play in the electromagnet 25, in order to keep the gap losses as low as possible.

Armature 33 and valve needle 12 are articulated to one another by a connecting member 3 ^l l , so that manufacturing-related axial offsets of armature 33 and valve needle 12 are compensated. A closing spring 35 presses the valve needle 12 with its valve cone 1'1 onto the valve seat 15 and holds the injection valve 10 in the closed position shown in FIG. 1.

A channel 36 connects to the inlet chamber 28 parallel to the inlet line 21, to which a return line 37 is connected, which is depressurized or depressurized and leads to a tank 38 from which the pressure source 19 sucks in the fuel via a suction line 39. Between the channel 36 and the return line 37 there is a compensating piston kl in a guide bore ^! ί2 is used and seals the channel 36 connected to the inlet space 28 from the return line 37.

309838/0037 ~ ¹⁰ ~

Robert Bosch GmbH R. Ks / Kb

Stuttgart

The compensating piston 'ti, the diameter of which with D _r . designated

K 1

and is at least approximately equal to the diameter D _{C1 of} the valve seat 15, has a first end face k ¹ ) which, as already described, is relieved of pressure; ie it is exposed to atmospheric pressure apart from small amounts of fuel leakage that may be in the line. A second end face hk of the compensating piston is acted upon by the inlet pressure p "of the pressure source 19 and on this side the compensating piston kl is connected to the armature 33 or to the connecting element") k and thus to the valve via a flexible connecting member 45, preferably made of spring steel wire needle 12 coupled.

FIG. 2 shows the injection valve 10 according to FIG. 1 in its open position. When the electromagnet 25 flows through it, the armature 33 is attracted and, via the connecting member 3'i, has brought the valve needle 12 against the force of the closing spring 35 into its position holding the valve seat I5 open, so that fuel flows from the feed line 21 via the channel 27 to the feed chamber 28 , the inflow channel 29 with the throttle point Jl, the pressure chamber 22 and the open valve seat 15 can flow to the nozzle openings l6 in order to be injected from there into the combustion chamber of an internal combustion engine in a known and not shown manner.

The second exemplary embodiment of a fuel injection valve 50 according to the invention, which is shown in FIG. 3 and is designed for attachment to a diesel engine, has in a first housing part 51 a nozzle body 53 inserted in a stepped bore 52 and a spring housing 5 ^. In the axial direction of the first housing part 5I , an electromagnet 55 and a second housing part 56 are connected , which are screwed together under the tensioning force of a clamping nut 57 with the interposition of known, unspecified sealing rings and sealing surfaces to form a pressure-tight association. - 11 -

309838/0037

Robert Bosch GmbH R. Ks / Jib

Stuttgart

On the second housing part 56 a connection part 58 for the power supply to the electromagnet 55 and an annular pipe connection part 59 with an Aiischlußstutzen 6l for a fuel supply line 21 'are placed secured against rotation and clamped with a ring nut 63 feet. The connecting _{parts 59 5} 6l and the ring nut 63 are centered on a tubular connector G ¹ I of the housing part 56, which has a channel 65 in the form of a zenfcralon longitudinal bore, which relieves pressure and is connected to the tank of the pressure source, not shown, via a return line 37 ' is. This return line 37 'and the fuel supply line 21 are connected in the same way as the corresponding lines 37 and J1 in FIG. 1 to a pressure source which corresponds to that shown in FIG.

In a bore 66 of the nozzle body 53, a valve needle "-igkeit 67 with a guide." Part 68 f lu. Used sdicht and geführt.-The associated guide diameter is denoted by D. Eiriom in the direction of flow of the fuel in front of a nozzle orifice 69 arranged valve seat Ji A pressure chamber 72 is adjacent in the nozzle body 53, and the valve seat 71 », the diameter of _{which is denoted by D« Q} (see FIG. 3a), is closed by a valve cone 73 of the valve needle 67. The valve cone 73 closes into the nozzle opening 69 dipping Drcsselsapfen 7 ^ in. A controlled in such a way Düsenöffmmg is generally of the so-called "pintle * ?." her known and the structural design of this game is from the drawn on an enlarged scale FIG. 3 "clearly zv seen. the inclination the tapered bore fcililiiiisn! the valve seat 71 in the broom body is steep in a known manner-:. _;! # -äis inclination of the valve cone 73 of the nozzle needle 67 avi:; vi-i;: rt _: to aiaen completely defined valve seat with the :; D \ irüli :: s3 ■ :. s ^ r Γ ^^ su preserved

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ÖAD ORiG (NAL

Jiobert Bosch GmbH R. Ks / Kb

Stuttgart

The fuel supply to the valve seat 71 adjacent Pressure chamber 72 takes place from the fuel supply line 21 ' via the connection piece 6l, via a respective bore 75 and in the connection part 58 or in the second housing part 56, through the electromagnet 55 1, a spring space 77 of the spring housing 5'i and the valve needle 67 through. The valve needle 67 has an inflow channel 78 in the form of a longitudinal bore through> two inclined transverse bores 79 are connected to the pressure chamber and in oiner extension 80 an exchangeable one Screw part 8l receives, in which a throttle point 82 is arranged, which has a designated with F throttle cross-section Has.

An armature, denoted by 83, of the electromagnet 55 is guided within the magnet with close play and is coupled with a tie rod via a coupling disk Hk with radial play, which connects the armature 83 to the Wntilnadel 67 with the interposition of a joint 86. This type of connection of the Vuiit il needle with the armature 83 allows the previously described close guidance of the armature 83 in the magnet 55, whereby a great magnetic force can be achieved in a very small space without guiding or frictional forces affecting the function of the valve.

The joint 86 consists of a rod head screwed onto the tie rod 85 , which has a crossbone 88 sunk deeply on both sides, and a pin 89 which is inserted through a cross-hole 1 ir. The valve needle 67 and the cross-hole 88 is. Since the rod head 87 has radial play compared to the extension 8ü egg valve needle 67 and the transverse bore 88 in the rod head 87 is countersunk to about half of its entire length, there is an articulated connection between the pull rod 85 and the valve needle 67. Deviations in the longitudinal axes of the valve needle

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Robert Bosch GmbH R. Ks / Kb

Stuttgart

and armature 83 can therefore not have an adverse effect perform the function of the injector. In extension of Valve needle 67 and armature 83 is connected to the pull rod 85 over a flexurally elastic, but nevertheless longitudinally rigid connecting member 92 is coupled to a compensating piston 93, which is in a Guide bore 9'i of a guide bush 95 is slidably fitted is. The guide bush 95 is in turn inserted into the second housing part 5 ° so as to be exchangeable and is there from a screw part 96 held. The flexible connecting link 92 is advantageously made of spring steel wire, in order to avoid lateral forces caused by positional deviations. The interchangeable guide bush 95 and the exchangeable screw part 8l facilitate the adjustment of the injector to the various engine conditions, due to which the valve seat diameters and valve needle shapes must be individually adapted in a known manner.

In the same way as in the case of the compensating piston kl in FIG. _o designated diameter of the compensating piston 93 equal or at least approximately equal to the diameter D "of the valve seat 7 ^ i in order to compensate or at least approximately compensate for the hydraulic forces loading the valve needle 67 in the closed state of the injection valve 50. The compensating piston 93 has, like the compensating piston 41 in FIG. 1, a first end face 97 and a second end face 97 and a second loaded by the inlet pressure p "dei ~ pressure source

/ j

Face 98 · This second face 98 has one Channel 99 in the second housing part 56 and an Irmenraum 101 of the electromagnet 55 connection with the spring chamber 771 of the, as already described, with the fuel supply line 21 'is connected. The balance piston 93 has grooves 93a pierced in its circumference, which form a labyrinth seal form so that the proportion of leak fuel

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BAD ORiGiNAL

Robert Bosch GmbH R. Ks / Kb

Stuttgart

flowing back through the return line 37 'into the tank Fuel is kept low. Between the Dohrung 75 in the second housing part 56 and the spring chamber 76 is the Inflowing fuel led around the designated 102 winding of the electromagnet 55, with a winding 102 surrounding space I03 through a channel 104 with the bore 75 and is connected via a channel 105 to the interior 101 of the electromagnet or to the spring chamber 76. The den Fuel flowing through space IO3 cools the winding 102 of the electromagnet 55

The spring chamber 771, the interior 101 of the electromagnet 55 and the channel 99 in the second housing part 56 together form an inlet chamber IO6, from which both the second end face 98 of the piston 93 and a stepped end face 107 of the valve needle 67 facing the spring chamber 76 with the Inlet pressure p "of the pressure source can be loaded. When the valve is closed, this inflow pressure p "naturally also prevails in the inflow channel 78 of the valve needle 67 and in the pressure chamber 72, since the throttle point 82 is not effective when no fuel is flowing.

A closing spring 10Ö, which is on the one hand on a step IO9 in the spring space 76 and on the other hand on a shoulder 111 the valve needle 67 is supported, holds the valve needle 67 in the closed position shown. Since the · compensating piston 93 » as will be shown in more detail later, ensures that in the closed state of the injection valve 50 the from the inlet pressure ρ on the valve needle 67 acting forces are balanced, the force of the closing spring I08 is advantageous in such a way on the Force of the electromagnet 55 coordinated that a desired closing and opening speed of the valve needle 67 is achieved. When injecting valve 50 is also through

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Robert Bosch GmbH R. Ks / Kb

Stuttgart

the closing spring 108 overcomes the force acting in the opening direction of a very weak spring 112 which only holds the armature 8j in its installation position and presses it against the clutch disk 84.

The third embodiment includes one. 120 designated fuel injector ». that, k in Fi & partially facing nozzle portion is shown in its lower the combustion chamber 3 differs vohi second embodiment of FIG. essentially in that it is designed as a so-called "hole-type nozzle. ¹¹ A valve needle 6 7 'has a guide member 68 'and then a slim needle valve 121 provided with a valve cone 73'. In the position shown, the valve cone 73 'closes a valve seat 71' in a nozzle body 53'j in a known manner by a clamping nut 122 with a housing part 123 of the injection valve 120. The nozzle body 53 'has - seen in the flow direction :) - below the valve seat 71' a blind hole 12 * 1, which is connected to the combustion chamber of the engine (not shown) through a bus incorporated into the wall of the nozzle body; 53 ' enof f openings 125. An inflow channel 78 'corresponding to the inflow channel? 8 in FIG ' and. a pressure chamber 72 'adjacent to the valve seat 7-'. The inflow channel 7'3 'is only interrupted in the filling part 68' of the valve needle 67 'in order not to weaken the needle part 121. A screw part 81 'provided with a throttle point 82' is screwed into the Zu ^ tröniiiiir.al 78 '. As in the case of the injection valve 50 in FIG. 3, there is a closing spring 108 in the spring chamber 77 ' ^! "Nter ^ tbrPiliw ynd a tie rod 85" connects the valve acel f " ^! Sn with an armature, not shown in detail, of an electrical magnet and a compensating piston. The parts not shown correspond essentially to those of the second embodiment. aiigsbeispiels according to Fig. 3.

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BAD ORiGiNAL

Robert Bosch GMBH . R. Ks / Kb

Stuttgart

The illustrated in Fig. 5 in its bottom, essential to the invention part of fourth embodiment of the fuel injector I30 has a with a guide part I3I guided in a nozzle body I32 valve needle 132 k similar to the valve needle 67 'in Fig. Possesses a slender needle member 133. In the position shown, this needle part 133 closes a valve seat 135i with a valve cone 13 ^, the seat diameter of which is denoted by D_. This valve seat 135 controls the passage of the fuel from a said valve seat to nozzle openings 137 · This lower part of the fuel injector I30 is in the same way as the corresponding part of the injection valves 10 and 120 of Figures 135 adjacent pressure chamber I36. 1.2 and k as so-called "Hole nozzle" formed.

The essential difference of the injection valve I3O of Fig. 5 with respect to the above-described injection valves according to FIGS. 1 to h is that a balance piston I38 between the valve needle 132 and the unspecified dargestellen armature is disposed a trained in known manner electromagnet. The diameter of this compensating piston I38 is denoted by D, and the

K3

Compensating piston I38 has a first end face ΐΊΐ facing valve needle 67 ', which closes off one side of a space l'l2 which is relieved of pressure and is connected via a channel I'l3 to a return line (not shown) leading to the tank. The space 1 ^ 2 and the channel 143 correspond to the pressure-relieved channel 65 in Fig. 3. A second end face Akk of the equalizing piston I38 is connected to the pressure source (not shown) of the injection valve I30 like an inflow channel labeled 1 ^ 5, so that both under the inlet pressure p "des of one only to

ti

Fig. 1 indicated pressure source I9 promoted Fuel. The inflow channel is 1 ^ 5 parallel to one receiving the compensating piston I38

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Robert Bosch GmbH R. Ks / Kb

Stuttgart

Guide bore 146 and parallel to the space 1 ** 2 incorporated into a housing part 147 of a pump housing 1Ί8 and has in its course a throttle point 151 accommodated in an intermediate plate 149 and designed as a throttle bore labeled l45a and opens into the pressure chamber I36. There, the fuel acts on a pressure shoulder I52 on the valve needle 132, which in the closed state of the valve extends outwards from a diameter of the guide part I3I of the valve needle 132 denoted _{by D ^ 0 and inwards from the cross-sectional area F "" des} Valve seat 135 is limited and

is-J

thus represents a ring surface in vertical projection.

The inflow channel 145 is facing away from the pressure chamber I36 End through an inclined part 145b with an inlet space I53 connected. This inlet space 153 is in. Its in Fig. 5 shown part of the valve needle 132 out second end face 144 of the compensating piston I38 and limited is formed by part of the guide bore 146 and the interior of the electromagnet, not shown. He is under the inlet pressure p "of the pressure source.

The compensating piston I38 is connected to the armature of the electromagnet in a manner not shown in detail via a tie rod 154 and is coupled to the valve needle 132 in a non-positive manner via a non-kinking connection member I55. _{The cross-sectional area F "o} corresponding to the diameter D of the compensating piston I38 is smaller _{by the cross-sectional area F c} corresponding to the diameter D of the valve seat 135 than the cross-sectional area F corresponding to the guide diameter D""of the valve needle I32, so that the hydraulic in the closed position forces acting on the valve needle are the same in both the opening and closing directions.

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Robert Bosch GmbH R. Ks / Kb

Stuttgart

The kink-proof connecting link 155 has, approximately in its middle, a collar 157 serving as an abutment for a closing spring 156 which has a spherically shaped support 58 for a spring plate 59 which accommodates one end of the closing spring 156. The spring plate 159 is shaped in accordance with the spherical support I58 and thus allows the position of the spring plate 159 to be adapted to any inclined position of the closing spring I56. Both ends of the connecting link each consist of a spherical head solder and 162, and each of these spherical heads I6l, l62 is mounted in a correspondingly spherical recess I63 and IGk of the compensating piston I38 or the valve needle 132. In order to eliminate tilting and lateral forces as far as possible, the center points of the ball heads 16I and I62 and the corresponding recesses I63 and 16'i are arranged so that they are at least approximately in the middle of the axial extensions of the respective guides of the compensating piston I38 and valve needle 132.

A fuel injection valve I70 shown in FIG. 6 as a fifth exemplary embodiment has one with a guide pin 171 in a bore 172 of a housing part 173 guided valve needle 17 ^ · The bore I72 penetrates the housing part 173 in the area of its combustion chamber side Face 175 and the guide pin I7I is in this Bore 172 fitted in a liquid-tight manner. To the housing part I73 closes a guide part I76 and in the axial direction a housing part 177, which houses an electromagnet I7Ö, which consists essentially of an armature 179 and a winding I8I. The housing part 173 and the guide part 176 are against each other by means of a clamping nut 182 and with the housing part 177 to form a pressure-tight association or screwed together to form a valve housing I83.

The housing part 177 and the clamping nut 182 are only partially shown on the not shown

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0 7 80

Robert Bosch GmbH R. Ks / Kb

• Stuttgart

Part of the valve housing I83 are in a known manner Connections for the fuel supply line and fuel return line appropriate.

A compensating piston I8 * i, the diameter of which is denoted by D ,, · and which is firmly connected to the armature 179 and coupled to the valve needle IJ ^ via a transverse pin I85, serves as the connecting link between the armature 179 and the valve needle 17 ^. The compensating piston 184 is lapped in a liquid-tight manner in a guide bore I86 of the guide part I76 and thus seals a pressure chamber I87, which is located between the bore 172 and the guide bore I86 and is acted upon by the inlet pressure p ", from a pressure-relieved interior I88 of the electromagnet I7Ö surrounding the armature 179 of the electromagnet. A return line returning the leak fuel to a tank is connected to this interior I88 in a manner not shown, and the pressure area I87 is connected to the pressure source not shown here via channels I89 in housing part 177 and channels I9I and I92 in guide part I76.

The guide pin 17I _1, the diameter of which is denoted by D "^, has the shape of a perforated nozzle tip with a blind hole 19 ^ and nozzle openings 195. The blind hole Iy ¹ I is closed to the inside of the valve needle with a plug I96 and has connecting bores 197 to an annular channel I98 am Circumference of the guide pin I7I · A valve cone I99 connects to the annular channel I98, which with the end of the bore 172 facing the pressure chamber I87 forms a valve seat 201. If this valve seat is sharp-edged, then the valve seat diameter designated by D "is equal to the guide diameter Dp ^. Since the valve seat 201 always has a radial extension in practice, it does

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Robert Bosch GmbH R. Ks / Kb

Stuttgart

only needs to be one to two tenths of a millimeter, it can be said that the valve seat diameter D, is at least approximately equal to the diameter D, of the guide pin 171. The diameter D, of the compensating piston is at least approximately equal to the diameter D, of the valve seat, and there the interior 188 of the electromagnet I78 is pressureless, is electromagnetic in this type of the actuatable fuel injection valve I70 at least one almost complete force compensation both when closed as well as when the valve seat 201 is open.

The sixth exemplary embodiment, a fuel injection valve 210 according to FIG. 7 differs from the fifth exemplary embodiment according to FIG. 6 only in a different design the valve needle and the housing in the area of the valve seat.

The injection valve 210 has a valve needle 17 ^ 'i which is guided with a guide piston 211 in a bore 212 in a housing part 173'. Below the guide piston 211, the valve needle I7V has a short needle part 213 with a valve cone 199'1 which, in the state shown, closes a valve seat 201 '. In the axial direction of valve needle I7V, valve cone 199 'is followed by a spray pin 21 * t, which penetrates a nozzle opening 215 and, with nozzle opening 215, forms a gap that is only used for a subset C) of the fuel quantity Q _{v to be} injected during full load operation. EJer injection pin 214 has an additional injection hole 216 in its center, which is open to the combustion chamber of the engine and is connected to the annular gap via a cross hole 2 "! _v or a partial load _{injection quantity Q Y} can be injected which is greater than the partial quantity Q ″ which can be injected through the annular gap.

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309838/0037

BATH ORIGINAL

Robert Bosch GmbH R. Ks / Kb

Stuttgart

Since the valve seat 201 · through the edge between the nozzle opening 215 and a conical seat surface 218 in the housing part 173 'is formed, the valve seat diameter D.

S5 ₅ loading

the diameter of the compensating piston 184 ¹ .

equal to or at least approximately equal to that with O _vr . loading

K5

All other parts of this fuel injector 210, e.g. the armature 179 of the electromagnet I78 are equal to the Parts of the fuel injection valve I70 according to FIGS. 6 and therefore neither designated in FIG. 7 nor described in relation to this figure.

In the following, the operation of the invention is now Fuel injection valve described with reference to the drawing.

In the case of the injection valve 10 of the first exemplary embodiment according to FIGS. 1 and 2, the closing spring 35 holds the valve needle 12 in its closed position as shown in the de-energized state of the electromagnet 25. The valve cone 14 seals off the valve seat I5 and prevents the passage of the fuel, which is under inlet pressure p 1 in the pressure chamber 22, to the nozzle openings 16. In the closed state of the valve, the inlet pressure p "also prevails in the inlet chamber 28. The following forces act on the valve needle 12: Force in the closing direction Pa = P" + p ". F "., Where P" is the force of the closing spring and F _{pl is} the cross-sectional area that is acted upon by the fuel inlet pressure and corresponds to the diameter D of the guide part 13 of the valve needle 12. At the same time, however, the force Pb = p "acts in the opening direction of the valve needle 12. (F ₁ ,. - F_. + F ^.) Against the force Pa, so that the effective closing force P. = Pa - Pb = P + ρ. (F - F), where F is the seat diameter

Γ ύ 'Ol Λ 1 Ol

D _{Ci of} the valve seat I5 corresponding cross-sectional area and F ^ ₁ the diameter D of the Au
speaking cross-sectional area.

the diameter D of the compensating piston 41 ent

309838/0037

-22-

Robert Bosch GmbH R. Ks / Kb

Stuttgart

If now, as stated at the beginning of the first exemplary embodiment, the diameter D ". of the compensating piston kl is equal to the diameter D _{1 of} the valve seat I5, the hydraulic forces resulting from the fuel inlet pressure p "cancel each other out and the closing spring 35 with its spring force Pp only holds the valve needle 12 in the drawn closed position.

With the same diameter of the compensating piston kl and valve seat I5, a complete hydraulic force equalization has been achieved with the injection valve closed.

However, it can also be desirable that, for example, a small excess force in the closing direction should support the closing movement of the valve needle 12 in order to increase the closing speed which is otherwise determined solely by the spring force P 1 of the closing spring 35. In this case, the hydraulic forces acting on the valve needle 12 in the opening and closing directions are only approximately the same; ie the diameter D ^. of the compensating piston / and thus its cross-sectional area F. are slightly smaller than the diameter D _{C1 of} the valve seat I5 or its cross-sectional area F.

The electromagnet 25 has to overcome P. at the moment of switching on; ie the pull-in force P .. of the electromagnet 21 only has to be greater than P " _{in the case in which F 5 = F.} From this it can be seen that the inlet pressure p_

Γ Li

has no influence on the pull-in force P _{M of} the electromagnet 25 required to open the valve when the force is completely balanced by the compensation piston kl.

The above-described equilibrium of forces is, however, immediately disturbed in the case of valves as described for FIGS. 1 and 2 (and also k) when the valve needle 12 of

309838/0037

- 23 -

O η C η

Robert Bosch GmbH R. Ks / Kb

Stuttgart

_{its valve seat I5 has lifted, because then the valve seat surface F 51} previously covered by the valve seat occurs as an additional surface acted upon by the fuel pressure and exerts an additional force on the valve needle in the opening direction. 12 off. Depending on the size of the added surface F on the valve needle 12 corresponding to the valve seat 15 and depending on the closing force of the closing spring 35 and the inlet pressure p ", the described circumstance leads to the valve needle 12 remaining in its open position, or at least the closing movement the valve needle 12 is delayed. This slow closing is also promoted by the so-called "sticking" of the armature 33 in the electromagnet 25, which is caused by the residual magnetism of the electromagnet.

In the case of the injection valve 10 according to the invention according to FIGS. and 2 now causes the throttle parts 31 inserted into the inflow channel 29 such a pressure drop ^ p between the inflow chamber 28 and the pressure chamber 22 that the hydraulic forces acting on the valve needle 12 also in the open state of the valve seat 15 shown in FIG The opening and closing directions are the same. As a result of the throttle point 31 and the pressure drop Λ P generated by this throttle, when the injection valve is open (FIG. 2) in the pressure chamber 22, a sr pressure p. ,,, = p “is reduced by A P. - Λ Ρ · The throttle cross section F of the throttle bar 31 is dimensioned so that the pressure P _n ., In the pressure chamber 22 with the injection valve 10 open is reduced so that the force acting in this pressure chamber 22 on the valve needle ϊ2 ir: Oz'imiKgsrielitiiiig P _r "same as the one when closed!"! Injection valve 10 in this pressure ram 22 on the Ytm ^ ilrtaüei 12 acting in the same direction force P ^, is, \ Iaruezi spiced up some excess forces in one or the other T- direction,

309838 / C037

BATH ORIGINAL

Robert Bosch GmbH R. Ks / Kb

Stuttgart

then these forces P and P are only approximate

open to

equalized.

If, as already mentioned, P = P, then only the respective pressure conditions in pressure space 22 need to be considered, because the areas F, _H and F *. and

rl Kl

the pressure p "in the inlet chamber 28 are both in the open as well as when the injector is closed,

Therefore the following equation can be set up in this case:

^P open = ^{P closed} - P ₀ ' ^(F F " ^F S ⁺ V ⁼ * Z' ^(F F" ^F S ⁾

In this equation, F _{v is} the valve opening cross section of the injection valve and in the first exemplary embodiment according to FIGS. 1 and 2, the cross section F _{v1 is} equal to the valve seat _{cross section Fc 1} , so the following equation applies to the first exemplary embodiment:

^P D1 · ^F F1 ^{= P} Z * ^(F il - ^F S1 ^K

From this equation it can be seen that the _{pressure p ni} reduced by the throttle parts 31 in the pressure chamber 22 becomes smaller in the same ratio as the area on the valve needle 12 which is acted upon by the fuel pressure in this pressure chamber 22 becomes larger.

The cross-section F of the throttle point 31, which generates the required pressure drop Δ ρ at a given inlet pressure p_, is also correct: ~: for variable inlet pressures and fuel quantities, since, in simple terms, the required pressure drop ^ ρ enti at a smaller or larger inlet pressure p "; is really smaller or larger. These

3 0 9838/0037 -25-

BATH ORIGINAL

_ 25 - υ ί ου

Robert Bosch GmbH R. Ks / Kb

Stuttgart

The assertion applies under two conditions, namely that the throttle cross-sections of the throttle point 31 and in the nozzle openings l6 or in the valve seat 15 are small compared to the upstream spaces 28 and 22 and that the pressure outside the injection valve, ie in the combustion chamber of the engine, is small compared to the inlet pressure p "and the pressure p". is because then

Zr L) X

By simply transforming the flow equation applicable to both flow points (throttle cross-section F _ni in throttle point 31 and flow cross-section at nozzle openings 16), the relationship p "- p _n1 = K can be derived. ρ,

Zf LJ A Yyyy

where K is a constant in which the constant flow characteristics and cross-sections of the throttling points contain are.

The second embodiment according to FIG. 3 operates in the same way as the first embodiment described with reference to FIGS. 1 and 2. As an important difference, however, it should be noted that when the injection valve 50 is open, the valve needle 67 does not release the full valve cross-section corresponding to the valve seat diameter D_, but that with this valve needle 67 provided with the throttle pin 7k , only an annular valve cross-section F "is released. This valve cross-section F _v , which in the open state of the injection valve 50 _{is acted upon by the pressure p, W)} in the pressure chamber 72 reduced by the throttle point 82, is generally considerably smaller than the cross-sectional area F _{co of} the valve seat 7I _{corresponding to the valve seat diameter D 5} Therefore, only a very small pressure drop A ρ needs to be generated by the throttle point 82. Is the difference between the diameter D "of the valve seat 71 and the diameter of the throttle pin ens very low, then it can be preferably dispensed at low injection pressures on the throttling by the throttle point 82 7 ¹ I.

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3 09838/0037

- ²⁶ - 0 7 80

Robert Bosch GmbH R. Ks / Kb

Stuttgart

A complete static and dynamic force equalization is achieved in the injection valve 50 in that the diameter D of the compensating piston 93 is equal to the diameter D of the valve seat "} \ , and in that the throttle point 82 is designed so that when the injection valve 50 is open it increases the pressure p _no in pressure chamber 72 so that the following equation applicable to injection valves 10, 50 and 120 (Fig. 1 to k) is fulfilled:

Pd ^(f f - ^F s ⁺ V = Pz ^(f f - V

If, in the fuel injection valve 50 according to FIG. 3, the diameter D ^ _{n of} the compensating piston 93 is the same and not just approximately the same as the diameter D of the valve seat 71, the following special equation applies in this case:

^P D2 * ^(F F2 - ^F S2 ^{+ F} V2 ^{) = P} Z ' ^(F F2 " ^F S2 ⁾ '

The third exemplary embodiment, the fuel injection valve 120 according to FIG. H , works in the same way as the first example described in connection with FIGS. 1 and 2. The valve needle 67 ¹ controls the valve seat 71 'with its valve cone 73' arranged at the end of the needle part 121. which, when the injection valve is closed, as shown in FIG. 4, prevents the fuel in the pressure chamber 72 'from passing through to the nozzle openings 125. When the injection valve 120 or valve seat 7I ¹ is open, as in the injection valve 10 according to FIG. 2, a ^{pressure drop controlled by the throttle point 82 1} takes place in the pressure chamber 72 ', which, as already described for FIG. 2, also occurs in the open state of the injection valve 120 causes a compensation of the hydraulic forces acting on the valve needle 67 '.

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309838/0037

Robert Bosch GmbH R. Ks / Kb

Stuttgart

The fuel injection valve I30 shown in FIG. 5 with its features essential to the invention is fuel pressure compensated in its closed position, ie the hydraulic forces acting on the valve needle 132 in the opening and closing directions from the inlet pressure p "are the same. This pressure equalization is achieved in that the cross-sectional area F _v , which corresponds to the diameter D of the compensating piston 138, is equal to the cross-sectional area which acts on the valve needle 132 in the opening direction in the pressure chamber I36. The following applies: F ", = F" _o - F _co , where F is the cross-sectional area of the guide part I3I of the valve needle 132 corresponding to the diameter D and F is the cross-sectional area of the valve seat 135 with the diameter D.

needle 132 and F "_ the cross-section corresponding to the diameter D" _

If fuel injection is to take place, the then switched-on electromagnet (not shown here) attracts the compensating piston 138 via the tie rod 15 ^, which is simultaneously followed by the valve needle 132, which is force-locked via the connecting member I55 and is loaded by the fuel pressure on the shoulder 152. The valve cone 13 ^ζ ί of the valve needle 132 lifts off the valve seat 135, and the fuel, which is under inlet pressure p ^ in the pressure chamber I36 before the injection, is injected through the nozzle openings 137 into the combustion chamber of the engine, which is not shown in detail.

During the injection there is now a pressure ρ reduced by / χ ρ by the throttle point I5I in pressure chamber I36, which causes the hydraulic forces acting on the valve needle to be balanced even when this injection valve I30 is open. This is the case if the force acting in the inlet chamber 153 on the compensating piston in the closing direction of the valve needle 132 is equal to the force acting in the pressure chamber I36 in the direction of the valve needle 132. Strength is "

3 0 8 8 3? / G C 3 7

BATH ORIGINAL

Robert Bosch GmbH R. Ks / Kb

Stuttgart

In fuel injection valves according to the invention, which like that Injection valve I30 (Fig. 5) between the armature of the Electromagnet and the valve needle 132 arranged compensating piston 138, a complete hydraulic force equalization can also be achieved when the injection valve is open, if in the design of the throttle point I5I the following equation is used:

^p D3 * ^(F F3 - ^F S3 ^{+ F} V3 ^{] = p} Z · ^F K3 '

where F _V o is the valve opening cross section.

Since, in the fuel injection valve I30 according to FIG. 5, the flow cross section F .., as in the exemplary embodiments according to FIGS. 1, 2 and 4, is equal to the cross sectional area F _{c of} the valve seat, the aforementioned equation is simplified as follows:

P ₀₃ ^F F3 = P _Z * ^F K3 *

From this equation it is easy to _{calculate p ß} _ or ^ p = P _z - p _D -.

In the fuel injection valve I70 according to FIG. 6, the fuel delivered by the pressure source, not shown in detail, reaches the pressure chamber I87 via the channels 189, 191 and 192, which partially surrounds both the valve needle 174 and the compensating piston 184. Since according to the invention the diameter D _K. of the compensating piston 184 is equal to the guide diameter Dp of the guide pin I7I and equal to the valve seat diameter D of the valve seat 201, and the interior I88 of the electromagnet I78 surrounding the armature 179 is depressurized, are those that act on the valve needle 174 in the closed state of the injection valve I70 as shown

309 838/0037 -29-

_ 29 - υ / ο

Robert Bosch GmbH R. Ks / Kb

Stuttgart

Forces equal in both opening and closing directions, which results in a static force balance. Therefore, l? 0 applies to this injection valve

\ k ^{= D} S4 ^{= 0} FV

Almost complete force compensation is achieved when these diameters are at least approximately the same.

When the electromagnet I78 is switched on, the armature 179 attracts the valve needle I74 via the compensating piston 184 and the pin I85, the valve cone I99 of which releases the valve seat 201. Can now under the inlet pressure "p in the pressure chamber I87 upcoming fuel through the annular channel fund the connection holes 197 in the blind hole 19 ^ reach and is injected from there through the nozzle openings 195 into the combustion chamber of the engine.

The fuel injector 210 of FIG. 7 operates in same way as that according to FIG. 6, only here the relation Dj applies. = D ", whereby the desired force compensation is achieved in the closed state.

With an open injection valve 210, an additional force in the opening direction acts on the valve needle I74 ^1, which is proportional to the fuel pressure and the annular surface which is delimited outwardly from the valve seat diameter D "and inwardly from the diameter of the pintle 114th In the case of a relatively low injection pressure and a narrow ring cross-section, this additional force is negligible; in the case of very high injection pressures and a larger ring gap, this force can be achieved by throttling between a space above and below the guide piston 201 (not shown) in a similar manner as with the injection valves according to FIGS. 1 to k. / f

309838/0037

- 30 -

Claims (1)

Robert Bosch GmbH R. Ks / Kb Stuttgart Expectations 1. Electromagnetically actuated fuel injection valve for internal combustion engines, whose valve needle guided in a bore of the valve housing is connected to the armature of an electromagnet and, when the electromagnet is excited, it lifts off the valve seat against the force of a closing spring and against the direction of flow of the fuel supplied by a pressure source under inlet pressure and one connects the pressure chamber adjacent to the valve seat with at least one nozzle opening, characterized in that the valve needle (12,67,67 ·, 132,174,174 «) is coupled to a compensating piston (41,93,138,104,184 ·) which is coaxial with the valve needle and armature (33,83,179) is guided in a sealing manner in a guide bore (42,94,146,186) of the valve housing and its first end face (43,97,141) is pressure-relieved, the second end face (44,98,144) is acted upon by the inlet pressure (p ") and its cross-sectional area (F _K ) is so large that when the injection valve is closed, the opening and Sch hydraulic forces acting on the valve needle (12,67,67 ', 132,174,174') are the same or at least approximately the same. 2. Electromagnetically actuated fuel injector according to claim 1, characterized in that the only connection between the pressure chamber (22, 72, 72 ', I36) and one 309838/0037 - 31 - - ^31-0780 Robert Bosch GmbH R. Ks / Kb Stuttgart facing the armature (33> 83) and from the second end face (44,98,144) of the compensating piston (41,93,138) Inflow space (28,106,153) is an inflow channel (29,78,78 ', 145) provided with a throttle point (31, 82,82', 151) (Figures 1 to 5). 3. Electromagnetically actuated fuel injection valve according to claim 2, characterized in that the throttle point (31 »82, 82, ¹ , 151) has a throttle cross-section (F.,) through which the pressure (p _ß ) when the injection valve (10, 50, 120, 130) is open in the pressure chamber (22,72,72 *, I36) is reduced so that the force (P _ ) is at least approximately equal to the force (P) acting in the same direction in the same space when the injection valve is closed (FIGS. 1 to 5). 4. Electromagnetically actuated fuel injection valve according to one of claims 1 to 3i, characterized in that the guide diameter (D.) Of the valve needle (12, 67, 67 ', 132) corresponding cross-sectional area (F _P1 ) is at least ten times as large as the flow cross-section (F _v1 ) of the valve seat <15.71i71 ^r t135) (Fig. 1 to 5). 5 · Electromagnetically actuated fuel injection valve according to one of the preceding claims, characterized in that 3 09838/0037 - 32 - - ³² - 07 8D Robert Bosch GmbH R. Ks / Kb Stuttgart that the compensating piston (4l, 93) is coupled to the valve needle (12,67,67 *) as an extension of the valve needle (12,67,67) and armature (33,03) via a flexible connecting member (45,92) and the diameter (D _1. ,) of the compensating piston (4l, 93) is equal to or at least approximately equal to the diameter (D _Q. ) of the valve seat (15,71,7I ¹ ) Ol, ti is (Figs. 1 to 4). 6. Solenoid actuated fuel injector according to claim 5, characterized in that the flexurally elastic The connecting link (45,92) consists of spring steel wire (Fig. 1 to 4) 7. Electromagnetically actuated fuel injector according to any one of claims 2 to 6, characterized in that the inflow channel (78,78 ') int substantially in the longitudinal axis of the valve needle (67,67' extends) and there in an expansion (80,8ο ¹⁾ a removable screw (8l , 8l ·) in which the throttle point (82,82 ') is arranged (Fig. 3 and 4). 8. Electromagnetically actuated fuel injection valve according to one of the preceding claims, characterized in that the guide bore (94) for the compensating piston (93) is arranged in an exchangeable guide bush (95) which leads into a channel (65 ') leading to a return line (37') ) of the valve housing (56) is firmly inserted ³⁾ · 309838/0037 """ Robert Bosch GmbH R. Ks / Kb Stuttgart Electrically actuated fuel injection valve according to one of Claims 1 to 4, characterized in that the compensating piston (I38) is arranged between the valve needle (132) and armature, connected to the armature and frictionally connected via a kink-proof connecting member (I55) is coupled to the valve needle (132), and that the cross-sectional area (F) corresponding to the diameter (D) of the compensating piston (I38) by the diameter (D "") of the valve seat K3 ^S 3 (135) corresponding cross-sectional area (F ^) is smaller than the cross-sectional area (F) corresponding to the guide diameter (D) of the valve needle (132) (Fig. 5) 10. Electromagnetically actuated fuel injector according to claim 9) characterized in that the kink-resistant The connecting member (155) has a collar (157) serving as an abutment for the closing spring (I56) (FIG. 5). 11. Solenoid actuated fuel injection valve according to claim 10, characterized in that the collar (157) has a spherically shaped support (I58) for one end the closing spring (156) receiving the spring plate (159) (Pig. 5). 12. Electromagnetically actuated fuel injection valve according to one of claims 9 to 11, characterized in that the rigid connecting member (155) ^a * i of its two 309838/0037 - 3k - - 3k - 0783 , Robert Bosch GmbH R. Ks / Kb Stuttgart Ends each has a ball head (l6l and l62), each of which in a correspondingly spherical recess (I63 and 164) from compensating piston (I38) and valve needle (132) is stored (Fig. 5). 13. Electromagnetically actuated fuel injector according to claim 12, characterized in that the respective spherical centers of the spherical heads (l6l, l62) and recesses (163, 164) at least approximately in the middle of the axial extensions the guides of the compensating piston (I38) and the valve needle (132) are (Fig. 5). 14. Electromagnetically actuated fuel injector according to one of claims 1 to 8, characterized in that the connection between valve needle (67) and armature (83) a tie rod (85) is at least opposite the (83) Armature /, which in turn is guided radially in the electromagnet (55), has radial play (Fig. 3) (5 ". Electromagnetically actuated fuel injection valve according to claim 14, characterized in that the pull rod (85) is connected to the valve needle (67) via a joint (86) is composed of a pin (89) penetrating the valve needle (67) and the pull rod (85) transversely to the valve needle axis and a transverse bore (88) countersunk on both sides in the tie rod (85) (FIG. 3). 309838/0037 - 35 - - 35 - 07 89 Bosch GmbH R. Ks / Kb Stuttgart 16. Electromagnetically actuated fuel injector according to claim 1, characterized in that the valve needle (17 ^) - seen in the direction of flow - behind the valve seat (201) liquid-tight with a guide pin (17I) in a bore (172) on the combustion chamber-side face (175) and of the valve housing (183,173) is guided, / that as a connecting member between the armature (179) of the electromagnet (I78) and the valve needle (17 ^) the compensating piston (l84) serves, whose diameter (D ,,.) at least approximately equal to the diameter (D,) of the guide pin (I71) and the diameter (D _5. ) Of the valve seat (201) is (Fig. 6). 17. Electromagnetically actuated fuel injector according to claim l6, characterized in that the guide pin (171) has the shape of a perforated nozzle tip and a blind hole (19 * 0 has the end facing away from the valve seat (201) the valve needle (17 ^ 0 is closed to the combustion chamber of the engine in a known manner the nozzle openings (195) contains and at least one connecting bore (197) to an annular channel (I98) controllable by the valve seat (201) in the The outer surface of the guide pin (I7I) has (Fig. 6). 18. Electromagnetically actuated fuel injection valve according to claim 1, characterized in that the valve needle (I73 ¹ ) - seen in the direction of flow - in front of the valve seat (201 ') 309838/0037 -36- Robert Bosch GmbH R. Ks / Kb Stuttgart a guide piston (211) and behind the valve seat (201 ¹ ) a nozzle opening (215) penetrating injection pin (21 (0) and that as a connecting member between the armature (179) of the electromagnet (17Ö) and the valve needle (l7 ^ ^f ) the compensating piston (184 ¹ ) is used, whose diameter (D _Kr ) is at least \ ■ approximately equal to the diameter (D) of the valve seat (201 ¹ ) is (Fig. 7). 19 · Electromagnetically actuated fuel injection valve according to claim 18, characterized in that the spray pin (21'O with the nozzle opening (215) forms a narrow annular gap which is only designed for a partial quantity (Q _T ) of the fuel quantity (Q _v ) to be injected during full load operation , and that the injection pin (214) has at least one additional injection bore (216) controllable after a pre-stroke (Hy) for the full-load injection quantity (Qy) or for a part-load _{injection quantity (Q x} ) which is greater than the sub-quantity <Q _{T that can be injected through the annular gap} ) is (Fig. 7). fif 309838/0037 Blank page