EP2479418B1 - Fuel injector valve - Google Patents

Description

State of the art

The invention relates to a fuel injection valve, in particular an injector for fuel injection systems of internal combustion engines. Specifically, the invention relates to the field of injectors for fuel injection systems of air compressing, self-igniting internal combustion engines.

From the DE 103 53 169 A1 An injector for injecting fuel into combustion chambers of internal combustion engines is known. The known injector has a piezoelectric actuator arranged in an injector body, which actuates a control valve accommodated in a valve plate. Further, a nozzle body is provided, at the brennraumseitigem end of a nozzle outlet is formed. A nozzle needle is axially movable or actuated in a longitudinal recess of the nozzle body. In addition, a rearward, facing away from the nozzle outlet end of the longitudinal recess final, arranged between the nozzle body and the control valve throttle plate is provided. The throttle disc forms an opening stop for the nozzle needle. The throttle disc acts in this case with the rear side, facing away from the nozzle outlet end face of the nozzle needle, so that the opening stroke of the nozzle needle is limited. In addition, a control space between the rear nozzle needle end face and the throttle plate is formed, which is in hydraulic communication with a pressure port for supplying fuel. Furthermore, a cylindrical holding body is arranged in the injector body, which accommodates a booster piston and a valve plate which contains the control valve. In a valve chamber of the control valve, a valve bolt is arranged with a valve body. The valve pin has a mushroom-shaped configuration. In this case, the valve body is acted upon by a valve spring arranged in the valve spring against a valve seat surface. The valve chamber is connected on the one hand via a throttle bore, which serves as an inlet and outlet throttle, with the control chamber. On the other hand, the valve space via a serving as a bypass bore with a high pressure Fuel room connected. The bypass bore can be closed by actuating the valve pin.

The from the DE 103 53 169 A1 known injector has the disadvantage that a relatively large volume of the valve chamber is required to accommodate the provided in the valve chamber components of the control valve. This results in a correspondingly large amount of reflux of fuel to a low pressure return. This refluxing fuel must be replenished from the high pressure. This has an unfavorable effect on the efficiency and makes a correspondingly high-pressure pump required.

Disclosure of the invention

The fuel injection valve according to the invention with the features of claim 1 has the advantage that an improved design of the control valve is made possible.
In particular, a volume of the valve space can be reduced, the power requirements of a high-pressure pump can be reduced and an improved opening and closing behavior can be achieved.

The measures listed in the dependent claims advantageous developments of the fuel injection valve specified in claim 1 are possible.

In order to achieve a fast nozzle needle closing in servo-controlled fuel injection valves, in particular piezoinjectors, the valve chamber pressure must be increased rapidly. The pressure increase depends on the valve volume, the fuel compressibility and the volume flow. Since the fuel compressibility is a constant, a faster pressure build-up at a given valve chamber volume can only be achieved by a higher inflow. This can be done via a bypass. However, in the case of an unconverted bypass amount, the control amount increases with increasing injection quantity and with higher pre- and post-injection number. This also increases the temperature of the actuator and the temperature of the fuel return system.

Advantageously, the valve spring can be moved out of the valve chamber. In combination with a direct connection of the drainage channel with the valve chamber, for example through a chamber inlet near the inlet, a very small valve chamber volume can be achieved. The drainage channel can in this case be designed as a throttled drainage channel. About the two sealing seats an antiphase valve control is possible, with opposite phase to the opening of the valve chamber to a Low pressure space a connection with the high pressure passage is possible, so that the valve chamber pressure increases rapidly. In this case, the control chamber can be supplied in addition to a filling via an inlet throttle or the like from the backflow through flow channel.

Thus, it can be achieved that the nozzle needle closes quickly, whereby a small quantity capability of the fuel injection valve is significantly improved and at the same time the maximum injection quantity per injection time is increased. As a result, for example, a specific engine power of the internal combustion engine can be increased.

Furthermore, a significant reduction in the amount of bypass, which is guided by the high-pressure passage in the valve chamber, can be achieved, whereby the delivery rate of the high pressure pump can be reduced accordingly. By using a high-pressure pump with a lower delivery rate, the drive torque can be reduced, whereby the drive train of the internal combustion engine only has to meet lower requirements. Furthermore, a lower-cost high-pressure pump can also be used. At the same time, the pump drive power is reduced, so that the efficiency improves.

Due to the reduced tax amount, there are further advantages. For example, pressure oscillations in the return system can be reduced, whereby the cavitation tendency is reduced. In addition, can be increased by the lower removal of quantities from the high-pressure passage of the nozzle pressure. Furthermore, the return temperature is reduced, which has a favorable effect on the Aktorhaltbarkeit and lower material requirements for the return system, in particular a return line, the result.

It is advantageous that in a first switching position of the valve body, the first sealing seat is closed and the second sealing seat is opened, that in a second switching position of the valve body, the first sealing seat is open and the second sealing seat is closed and that an actuator is provided for Adjusting the valve body from the first switching position into the second switching position is used. Specifically, the actuator may be configured as a piezoelectric actuator. As a result, an opposite-phase control is possible, which in particular allows a rapid closing of the nozzle needle of the fuel injection valve, which can be actuated via the pressure in the control chamber.

According to the invention, it is provided that the valve body has a sealing edge assigned to the first valve seat surface, and that the sealing edge of the Valve body cooperates with the first valve seat surface to the first sealing seat. In this case, the first valve seat surface is designed as an at least substantially planar first valve seat surface and the first valve seat surface is oriented at least approximately perpendicular to a valve axis of the control valve. Furthermore, it is advantageous that the first valve seat surface is configured on a seat plate. In this way, a flat valve seat can be configured on the first sealing seat. This facilitates in particular a centering of the individual components, in particular the seat plate with the first valve seat surface with respect to a guide of the valve body.

It is advantageous that a second valve seat surface is provided, that the valve body has a sealing surface assigned to the second valve seat surface, and that the sealing surface of the valve body interacts with the second valve seat surface to form the second sealing seat. About the second sealing seat can be switched to a certain extent a bypass. It is also advantageous that a sealing edge is configured on the second valve seat surface and that the sealing surface of the valve body cooperates with the sealing edge of the second valve seat surface to form a second sealing seat. It is also advantageous that the sealing surface of the valve body is designed as at least approximately conical sealing surface. This allows a certain centering of the valve body of the valve pin with respect to the sealing edge on the second valve seat surface. This also allows a reliable seal on the one hand both on the first sealing seat and on the other hand on the second sealing seat. This results in a favorable switching behavior, which in particular allows short switching times for actuating the nozzle needle.

Advantageously, the second valve seat surface is configured on a valve plate. This results in a compact design of the control valve with a reduced number of components. This also simplifies the assembly of the fuel injection valve.

However, it is also possible that a guide sleeve is provided, that the valve pin is guided in the guide sleeve and that the second valve seat surface is configured on the guide sleeve. Here, it is also advantageous that a valve plate is provided, that the valve plate has a recess, that the guide sleeve is arranged in the recess of the valve plate, that an applied to the valve plate throttle plate is provided, that the guide sleeve a side of the throttle plate associated biting edge characterized in that the guide sleeve cooperates with its biting edge with the side of the throttle plate and that a projection of the biting edge is predetermined with respect to the side of the throttle plate. Here, the guide sleeve with a press fit be arranged pressure-tight in the valve plate. The sealing of the guide sleeve to the throttle plate is ensured here via the biting edge, which has a pressure in the ready state, which is above that which is introduced through the injector in the plate association. This can be achieved for example by a defined assembly projection of about 2 microns to about 4 microns.

Also possible is a sealing of the guide sleeve relative to the throttle plate by an annular surface which is arranged in a plane to the valve plate sealing surface and in the ready state has a pressure which increases with increasing fuel pressure due to the resulting pressure force and thereby buckling of the throttle plate in the direction of the valve plate and thus the increasing tightness. This is achieved by the pressurized throttle plate area on the nozzle side opposite the valve plate side.

Thus, it is also advantageous that a valve plate is provided, that the valve plate has a recess, that the guide sleeve is arranged in the recess of the valve plate, that the pressure applied to the valve plate throttle plate is provided, that the guide sleeve, the sealing surface of the throttle plate associated annular surface and that the guide sleeve cooperates with its annular surface with the sealing surface of the throttle plate.

It is also advantageous that the valve chamber of the control valve is designed as an at least substantially annular valve space. It is also advantageous that a height of the valve space is determined at least substantially by an axial distance of the first sealing seat on the first valve seat surface to the second sealing seat on the second valve seat surface. As a result, a volume of the valve chamber can be optimized. Specifically, a relatively small volume of the valve space may be predetermined. As a result, the amount of rejected fuel can be optimized.

The fuel injection valve can also be configured in one of the following ways and optionally further developed in a suitable manner.

In this regard, a fuel injector, in particular an injector for fuel injection systems of air-compressing, self-igniting internal combustion engines, with a control valve and a control chamber, wherein the control chamber is connected via a drain passage with a valve chamber of the control valve, wherein the control valve receives a guide sleeve in a recess, wherein the guide sleeve at least on a part of the circumference is acted upon by high fuel pressure, wherein a valve pin is guided in the guide sleeve and wherein the valve pin has a valve body arranged in the valve body.

A possible development of this fuel injection valve is characterized in that the valve body cooperates on the one hand with a first valve seat surface to a first sealing seat, via which a connection of the valve chamber with a pressure-relieved space is controllable, and that the valve body on the other hand cooperates with a second valve surface to a second sealing seat , via which a connection of the valve chamber with a high pressure channel is controllable.

Brief description of the drawings

• Fig. 1 ein Brennstoffeinspritzventil in einer auszugsweisen, schematischen Schnittdarstellung entsprechend einem ersten Ausführungsbeispiel der Erfindung;
• Fig. 2 den in Fig. 1 mit II bezeichneten Ausschnitt des Brennstoffeinspritzventils des ersten Ausführungsbeispiels der Erfindung;
• Fig. 3 den in Fig. 1 mit III bezeichneten Ausschnitt des Brennstoffeinspritzventils des ersten Ausführungsbeispiels der Erfindung;
• Fig. 4 den in Fig. 1 mit IV bezeichneten Ausschnitt des Brennstoffeinspritzventils des ersten Ausführungsbeispiels der Erfindung in einem Fertigungszustand;
• Fig. 5 den in Fig. 4 dargestellten Ausschnitt des Brennstoffeinspritzventils des ersten Ausführungsbeispiels im Betrieb;
• Fig. 6 ein Brennstoffeinspritzventil in einer auszugsweisen, schematischen Schnittdarstellung entsprechend einem zweiten Ausführungsbeispiel der Erfindung;
• Fig. 7 den in Fig. 6 mit VII bezeichneten Ausschnitt des Brennstoffeinspritzventils des zweiten Ausführungsbeispiels;
• Fig. 7A den in Fig. 7 dargestellten Ausschnitt des Brennstoffeinspritzventils in einer weiteren möglichen Ausgestaltung;
• Fig. 8 eine auszugsweise Darstellung des in Fig. 7 dargestellten Brennstoffeinspritzventils des ersten Ausführungsbeispiels im Betrieb bei niedrigem Druck;
• Fig. 9 den in Fig. 8 mit IX bezeichneten Ausschnitt des Brennstoffeinspritzventils des zweiten Ausführungsbeispiels bei niedrigem Druck;
• Fig. 10 den in Fig. 8 dargestellten Ausschnitt des Brennstoffeinspritzventils des zweiten Ausführungsbeispiels im Betrieb bei hohem Druck und
• Fig. 11 den in Fig. 10 mit XI bezeichneten Ausschnitt des Brennstoffeinspritzventils des zweiten Ausführungsbeispiels im Betrieb bei hohem Druck.

Preferred embodiments of the invention are explained in more detail in the following description with reference to the accompanying drawings, in which corresponding elements are provided with identical reference numerals. It shows:

• Fig. 1 a fuel injection valve in an excerpt, schematic sectional view according to a first embodiment of the invention;
• Fig. 2 the in Fig. 1 labeled II section of the fuel injection valve of the first embodiment of the invention;
• Fig. 3 the in Fig. 1 III labeled section of the fuel injection valve of the first embodiment of the invention;
• Fig. 4 the in Fig. 1 with IV designated section of the fuel injection valve of the first embodiment of the invention in a manufacturing state;
• Fig. 5 the in Fig. 4 illustrated section of the fuel injection valve of the first embodiment in operation;
• Fig. 6 a fuel injection valve in a partial, schematic sectional view according to a second embodiment of the invention;
• Fig. 7 the in Fig. 6 labeled VII section of the fuel injection valve of the second embodiment;
• Fig. 7A the in Fig. 7 illustrated section of the fuel injection valve in a further possible embodiment;
• Fig. 8 a partial representation of the in Fig. 7 illustrated fuel injection valve of the first embodiment in operation at low pressure;
• Fig. 9 the in Fig. 8 labeled IX section of the fuel injection valve of the second embodiment at low pressure;
• Fig. 10 the in Fig. 8 shown section of the fuel injection valve of the second embodiment in operation at high pressure and
• Fig. 11 the in Fig. 10 XI designated section of the fuel injection valve of the second embodiment in operation at high pressure.

Embodiments of the invention

Fig. 1 shows a first embodiment of a fuel injection valve 1 of the invention in a schematic, partial sectional view. The fuel injection valve 1 can serve in particular as an injector for fuel injection systems of air-compressing, self-igniting internal combustion engines. A preferred use of the fuel injection valve 1 is for a fuel injection system with a common rail, the diesel fuel under high pressure leads to a plurality of fuel injection valves 1. However, the fuel injection valve 1 according to the invention is also suitable for other applications.

The fuel injection valve 1 has housing parts 2, 3, which are connected to one another via a nozzle lock nut 4. In the housing part 2, which is designed as a nozzle body, a fuel chamber 5 is configured. In the fuel chamber 5, a needle sleeve 6 is arranged, which encloses a nozzle needle 7 in the region of its end face 8.

In addition, a seat plate 9, a valve plate 10 and a throttle plate 11 are provided.

Through the seat plate 9, the valve plate 10 and the throttle plate 11 is a high pressure passage 12 with channel sections 13, 14, 15 out. About the high pressure passage 12 of the fuel chamber 5 is filled in operation with high pressure fuel. The needle sleeve 6 is supported on one side 16 of the throttle plate 11. Within the Needle sleeve 6 is limited between the side 16 of the throttle plate 11 and the end face 8 of the nozzle needle 7, a control chamber 17. The control chamber 17 is sealed off from the fuel chamber 5.

Between the channel sections 14, 15 of the high-pressure channel 12, an inlet channel 18 branches off with an inlet throttle 19. The inlet channel 18 opens on the one hand in the high pressure passage 12 and on the other hand in the control chamber 17. In this way, the control chamber 17 is filled with high pressure fuel.

Between the channel section 14 and the channel section 15 of the high-pressure channel 12, moreover, a filling channel 20 branches off from the high-pressure channel 12. The filling channel 20 opens into an annular space 21. The annular space 21 is thus connected to the high-pressure channel 12.

In addition, a drain channel 22 is provided with an outlet throttle 23. The drainage channel 22 opens on the one hand into the control chamber 17 and on the other hand into an annular valve chamber 24 of a control valve 25.

The control valve 25 comprises a valve pin 26. The valve pin 26 has a valve body 27 which is arranged in the valve chamber 24. As a result, an at least approximately annular valve space 24 remains free.

Hereinafter, the fuel injection valve 1 of the first embodiment is also with reference to FIGS. 2 and 3 further described. Fig. 2 shows here the in Fig. 1 labeled II section of the fuel injection valve 1 of the first embodiment. Fig. 3 shows the in Fig. 1 III section of the in Fig. 1 illustrated fuel injection valve 1 of the first embodiment.

The valve pin 26 of the control valve 25 is actuated via an actuator 28, as illustrated by the double arrow 29. The actuator 28 may be configured, for example, as a piezoelectric actuator.

The control valve 25 has a valve axis 30. The valve pin 26 with the valve body 27 is adjustable along the valve axis 30 of the actuator 28.

In the de-energized state of the actuator 28, the valve pin 26 is due to the excess force of a valve spring 35 against a coupler spring 36 in an upper rest position in which a first sealing seat between the valve body 27 and the seat plate. 9 closed is. In this case, the valve body 27 cooperates with a first valve seat surface 37 which is configured on the seat plate 9. The control valve 25 has an axis 38 along which the valve pin 26 is adjustable by means of the actuator 28. In this case, the valve pin 26 is guided along the axis 38. In this embodiment, the first valve seat surface 37 is oriented perpendicular to the axis 38. Here, the first valve seat surface 37 is designed as a flat first valve seat surface 37. In addition, one of the first valve seat surface 37 associated sealing edge 39 is formed on the valve body 27, which cooperates with the first valve seat surface 37.

In this embodiment, the sealing edge 39 is formed by two cones. The associated first valve seat surface 37 is designed plan. Here, the first valve seat surface 37 is provided on one side 40 of the seat plate 9. The formed first sealing seat has a sealing diameter 41 '. With the sealing diameter 41 ', the valve space 24 is sealed against a pressure-relieved space 41. The depressurized space 41 may be connected to a low pressure return. The conical surfaces, which form the sealing edge 39 in their intersection, have angles 42, 43. The outer conical surface in this case has an angle 42 in the range of about 10 ° to about 20 °. The inner cone surface has an angle 43 in the range of about 1 ° to about 2 °.

When energizing the actuator 28, a coupler piston 44 is actuated, which acts on an end face 45 of the valve pin 26 and the valve pin 26 is adjusted upon reaching a certain opening force. Here, the valve body 27 of the valve pin 26 lifts with its sealing edge 39 from the first valve seat surface 37, so that the first sealing seat is opened. Thus, a stroke-dependent flow cross-section between the pressure-relieved space 41 and the valve space 24 is released at the first sealing seat, via which fuel can flow out of the valve space 24 into the pressure-relieved space 41.

The flow cross-section at the first sealing seat increases until the valve pin 26 comes into contact with its valve body 27 against a second valve seat surface 46. The second valve seat surface 46 is designed in this embodiment as a conical second valve seat surface 46. Here, a sealing edge 47 is configured on the second valve seat surface 46. Further, a sealing surface 48 is formed on the valve body 27, which is at least approximately conical in the region of the second valve seat surface 46 and the sealing edge 47. The sealing surface 48 of the valve body 27 is in this case facing away from the sealing edge 39 of the valve body 27. As a result, on the one hand the first sealing seat between the sealing edge 39 and the first valve seat surface 37 on the valve body 27 formed while on the other hand, a second sealing seat between the sealing surface 48 and the sealing edge 47 is formed. When the valve body 27 abuts against the second valve seat surface 46 at a maximum actuation travel, the second seal seat is closed while the first seal seat is opened with a maximum flow cross section. A valve lift 49 is given geometrically by the axial distance between the sealing edge 39 on the valve body 27 and the sealing surface 48.

The second valve seat surface 46 is preferably designed as a conical valve seat surface 46, which extends in a straight line in cross section up to the sealing edge 47. Accordingly, the sealing surface 48 is configured as a conical sealing surface 48 which extends in the region of the sealing edge 47 in a straight line across the sealing edge 47 addition. In the region of the sealing edge 47, a slight depression is preferably provided which has predominantly concentric grooves.

Via the second sealing seat, a connection of the valve chamber 24 with an annular gap 50 can be controlled. The annular gap 50 is in this case connected to the filling channel 20, so that in operation in the annular gap 50 is under high pressure fuel.

When the first sealing seat and closed second sealing seat is open, on the one hand there is a connection between the valve space 24 and the pressure-relieved space 41, while on the other hand the connection of the valve space 24 to the annular gap 50 and thus to the high-pressure passage 12 is blocked. Thus, fuel flows from the valve chamber 24 into the pressure-relieved space 41, so that the pressure in the valve chamber 24 decreases to a lower equilibrium pressure. Accordingly, fuel flows from the control chamber 17 via the throttled drain passage 22 into the valve chamber 24. Thus, the pressure in the control chamber 17 decreases. The feed of the fuel into the valve chamber 24 can be achieved via a feed pocket 51, which is configured in the seat plate 9. This avoids stress-increasing intersections. The inlet pocket 51 is in an annular stitch, which ensures a uniform inflow and also the first valve seat surface 37 separates from the rest of the contact surface of the seat plate 9 on its side 40, whereby production is simplified.

Due to the reduced pressure in the control chamber 17, which acts on the end face 8, the hydraulic closing force on the nozzle needle 7 decreases, so that it comes to opening the nozzle needle 7. As a result, fuel from the fuel injection valve 1 can be injected into a combustion chamber of an internal combustion engine.

The control valve 25 has two different functions. One function is the actual control valve function, which is mediated via the first sealing seat between the valve body 27 and the first valve seat surface 37. The other function is a bypass valve function, which is mediated via the second sealing seat between the valve body 27 and the second valve seat surface 46. During the movement of the valve pin 26, both the first sealing seat and the second sealing seat are open. Thus, the control valve 25 allows simultaneous opening both with respect to the actual control valve function and with respect to the bypass valve function. In this case, a certain subset of the fuel from the high-pressure region, in particular the annular gap 50, via the first sealing seat, the valve chamber 24 and the second sealing seat is driven directly into the pressure-relieved space 41. However, since the movement of the valve pin 26 can be carried out very quickly and thus both sealing seats are open only for a short time, this additionally controlled amount of fuel is very low.

Therefore, a sufficient pressure drop in the control chamber 17 is achieved after a short time, so that the nozzle needle 7 can be driven relatively quickly to open. The nozzle needle 7 in this case continues its opening movement at the speed, which is determined by the flow of the preferably kavitierend designed outflow throttle 23 and the inlet throttle 19. When the actuator 28 is unloaded and the valve pin 26 is returned to its original position by the valve spring force acting on the valve spring 35 via a spring washer 52 and a supporting hydraulic closing force in which the first sealing seat is closed and the second sealing seat is open, then the Pressure in the valve chamber 24 again.

With the lifting off of the sealing surface 48 of the valve body 27 of the second valve seat 46 fuel flows from the high-pressure region via the filling channel 20 and the annular gap 50 in the valve chamber 24. Depending on the design of the fuel injector 1, in particular the control valve 25, fuel from the control chamber 17th via the drainage channel 22 into the valve chamber 24. Since the valve space volume of the valve chamber 24 can be very small, this leads to a very rapid increase in pressure in the valve chamber 24. Accordingly, the pressure of the fuel in the control chamber 17 increases rapidly. In this case, the fuel can be supplied via the inlet throttle 19 in the control chamber 17.

If in this case the same pressure in the valve chamber 24 as well as in the control chamber 17 is reached, then the fuel can also flow via the filling channel 20 and backward via the drain passage 22 into the control chamber 17, so that the pressure build-up in the control chamber 17 is further accelerated. As a result, a very fast closing of the nozzle needle 7 is achieved. Thus, the seat throttle area of the nozzle needle 7 can be traversed quickly, resulting in a better mixture preparation. Furthermore, a steep flow flank of the injection rate can be achieved, which increases the total amount of fuel in the maximum injection time. This gives a high specific power.

The configuration of the fuel injection valve 1 of the first embodiment is hereinafter also with reference to the 4 and 5 further described. Fig. 4 shows the in Fig. 1 With IV designated section of the fuel injection valve 1 in a manufacturing state or at a relatively low pressure. Fig. 5 shows the in Fig. 4 illustrated section of the fuel injection valve 1 of the first embodiment in operation at a relatively high pressure. The opening and closing force for actuating the valve pin 26 with the valve body 27 can be advantageously reduced, so that an operating force is reduced. For this purpose, the valve pin 26 is guided in a guide sleeve 25 which is pressed into the valve plate 10, as shown in the Fig. 1 is shown. The guide sleeve 55 has an annular surface 56. The annular surface 56 is in this case provided on an end face of the guide sleeve 55, which faces the throttle plate 11. The annular surface 56 of the guide sleeve 55 rests against the throttle plate 11 and is acted upon against the sealing surface of the throttle plate 11 with a sealing force, so that a spring chamber 57, in which the valve spring 35 is arranged, is sealed by the high-pressure-carrying areas. As a result, arranged in the spring chamber 57 end face 58 of the valve pin 56 is acted upon by the return pressure. The spring chamber 57 is for this purpose connected by means of a relief hole 59 with the pressure-relieved space 41 and a return line or the like. On the other hand, from the end face 45 of the valve pin 26 forth to the sealing diameter 41 'also the return pressure of the pressure-relieved space 41. Thus, the hydraulic pressure acting forces on the valve pin 26 are significantly reduced, whereby the opening and closing forces are low even at high pressure.

To reliably close the second sealing seat in the actuated state and to achieve an adequate seal with respect to the high pressure in the annular gap 50, a certain holding force is required. This necessary holding force with which the valve body 27 is pressed against the second valve seat surface 46, can be reduced by a sealing diameter 60 is designed with a small difference in diameter to a guide diameter 61 of the guide sleeve 55. Because this results in a very small pressure acting surface.

The valve pin guide of the valve pin 26 on the guide diameter 61 of the guide sleeve 55 is designed so that the guide takes place with a very small clearance and a defined distance from the end face of the throttle plate 11. Here, a guide clearance via a radial gap 26 between the valve pin 26 and the guide sleeve 55 is set so that at a gap entrance 63 and at a gap exit 64 a required minimum clearance for a clamping freedom at all operating pressures. In between, the preferred manufacturing shape is preferably set so that the game is equal to or greater. This ensures that due to deformations as a result of the pressure gradient differences between an outer side of the guide sleeve 55 and an inner side of the guide sleeve 55, the smallest operating gap always lies on the throttle plate-side gap outlet 64.

Fig. 4 illustrates the leadership situation for relatively low rail pressures. The designed as a radial gap 62 guide gap 62 is configured tapered from the gap entrance 63 to the gap outlet 64, since a sealing sleeve deformation by the compressive forces is not or only to a small extent. This corresponds to the manufacturing state. As a result, due to the laminar flow along the guide gap 62, an approximately linearly decreasing pressure curve sets in. Along the outer sealing sleeve results in a constant pressure curve. In the initial state, therefore, a radial gap width 65 at the gap entrance 63 is greater than a radial gap width 66 at the gap exit 64.

As it is in the Fig. 5 is shown, the diameter of the guide sleeve 55 decreases due to the differences in pressure force initially substantially in the region of the gap entrance 63 when the rail pressure increases, since the rail pressure at the periphery is fully effective. A leakage quantity dQ with a constant radial gap width s and a predetermined length L of the guide sleeve 55 then results approximately as a product of the rail pressure p and a fractional value with a numerator which is the third power of the radial gap width s and a denominator equal to the length L the guide sleeve 55 is.

From a mean rail pressure, for example, between about 120 MPa (1200 bar) and 160 MPa (1600 bar), the rail pressure p reaches the structurally determined pressure between the guide sleeve 55 and the valve plate 10, so that, depending on the number and the axial extent of annular grooves 67, 68 on the outside of the guide sleeve 55, a pressure infiltration sets in the pressure areas. If the rail pressure continues to increase, only the rail pressure p is effective in these areas. Since the pressure gradient in the guide gap 62 decreases in the direction of the throttle plate to the relief pressure, it is advantageous to allow the pressure between the guide sleeve 55 and the valve plate 10 to rise in the direction of the throttle plate 11. ideally Way, the pressure curve is set so that from this pressure threshold results in a largely uniform guide bush deformation. However, the manufacturing management game and the Führungshülseneinschnürung are coordinated so that the guide gap 62 throttle plate side is the smallest and advantageously becomes very small at very high rail pressure, the sum of the roundness errors of the valve pin 26 and the guide sleeve 55 is observed. The amount of leakage dQ thereby also assumes extremely small values. The resulting pressure curve along the guide gap 62 due to the laminar flow assumes in this case an approximately rectangular course, so that a self-stabilizing state is established, which ensures a jam-free guidance with at the same time minimum leakage quantity. This is also on the basis of 10 and 11 further described.

In the fuel injection valve 1 of the first embodiment, the guide of the valve pin 26 takes place in the guide sleeve 55, while the second valve seat surface 46 is configured on the valve plate 10.

Fig. 6 shows a fuel valve 1 in a partial, schematic sectional view according to a second embodiment. In this embodiment, the drainage channel 22 has channel sections 70, 71, 72. Here, the channel portion 70 of the drain channel 22 extends through the throttle plate 11. The channel portion 71 extends through the valve plate 10. Further, the channel portion 72 extends through the seat plate. 9

In this embodiment, the guide sleeve 55 is designed in one piece with a valve seat body 73. In this case, radial bores 74, 75 are provided in order to connect the annular gap 50 with the high-pressure region. The annular gap 50 is configured in this embodiment between the valve pin 26 and the valve seat body 73. In addition, on the valve seat body 73, the second valve seat surface 46 is formed with the sealing edge 47. Since the valve pin is guided in the guide sleeve 55 formed integrally with the valve seat body 73, a centering of the valve body 27 with respect to the second valve seat surface 46 is thus ensured. Since the first valve seat surface 37 is also designed as a flat first valve seat surface 37, a reliable closing of the first sealing seat is ensured. Due to the planar design of the first valve seat surface 37, a certain tolerance compensation is given constructively.

In this embodiment, a simple production and assembly is possible. In addition, a further reduction of leakage is possible, since a pressure-reduced guide clearance is achieved. The pressure-reduced guide clearance is achieved here by a hollow cylindrical outer annular gap 76 which surrounds the guide sleeve 55 on its outer side and with can be filled under high pressure fuel. As a result, the pressure forces of the fuel over the entire guide sleeve circumference fully effective.

Thus, in this embodiment, the guide sleeve 55 extends axially with the valve seat body 73 through the entire valve plate 10. On the side of the actuator 28, the guide sleeve 55 is pressure-tight manner by a press fit of the valve seat body 73 in the valve plate 10. Here, the seat plate 9 facing end face 77 of the valve seat body 73 is flush with the sealing surface on the seat plate 9 and forms with this a common sealing surface. The uniformly distributed over the circumference radial bores 74, 75 serve as connecting holes 74, 75 which connect the central bore of the guide sleeve 55 with the outer annular gap 76.

The outer annular gap 76 extends over the entire circumference of the guide sleeve 55 from the throttle plate 11 to slightly beyond the radial bores 74, 75 also. A radial width of the outer annular gap 76 is in this case set so large that an unthrottled inlet via the filling channel 20 serving as a bypass channel is possible over the resulting cross section. The filling channel 20 is configured in this embodiment in the throttle plate 11 and has a certain throttling. As a feed into the outer annular gap 76 is a lateral recess 78, which is designed in the region of the sealing surface in the valve plate 10.

In the in the Fig. 6 illustrated embodiment, the guide sleeve 55 is inserted into a recess 31 of the valve plate 10, wherein the recess 31 is configured as a continuous recess 31 in the valve plate 10. Here, in this embodiment, the guide sleeve 55 and the valve seat body 73 configured, resulting in a compact design. The guide sleeve 55 is inserted into the recess 31 of the valve plate 31, wherein the recess 31 is configured as a continuous recess 31 in the valve plate 10. Here, in this embodiment, the guide sleeve 55 and the valve seat body 73 configured, resulting in a compact design. The guide sleeve 55 is preferably pressed into the recess 31 of the valve plate 10.

Thus, the volume of the valve chamber 24 can be optimized. Specifically, the volume of the valve chamber 24 can also be chosen very small. Due to the annular configuration of the valve chamber 24, the volume of the valve chamber 24 can be set in an advantageous manner by the configuration of the valve body 27. Specifically, a height of the valve body 27 may be at least approximately equal to an axial distance 32 between the first sealing seat and the second sealing seat. This arises as the first Valve seat surface 37 is oriented perpendicular to the valve axis 30 and the sealing edge 47 is provided largely on the inside of the second valve seat surface 46. A height of the valve chamber 24 is determined here at least approximately equal to the axial distance 32 or at least substantially by the axial distance 32. In order to simplify the manufacture, however, a feed pocket 51 may be provided on the adjacent seat plate 9 or the like, which also contribute to the volume of the valve space 24.

Fig. 7 shows the in Fig. 6 labeled VII section of the fuel injection valve 1 of the second embodiment. The sealing of the guide sleeve 55 to the throttle plate 11 is achieved by a biting edge 79, which is designed on the guide sleeve 55. In the operational state of the fuel injection valve 1, the biting edge 79 with respect to the throttle plate 11 on a pressure which is higher than that which is introduced through the Injektorverschraubung in the plate assembly. This is achieved by a defined mounting projection of the biting edge 79 with respect to a sealing surface 80 on the throttle plate 11. This assembly projection can be, for example, in the range of about 2 microns to 4 microns. A biting edge diameter of the biting edge 79 preferably corresponds at least approximately to an outside diameter of the guide sleeve 55. This ensures that axial pressure forces do not excessively reduce the biting edge pressure during operation. In addition, the Beißkantenpressung is reinforced by transverse contraction forces due to the pressure forces acting on the outside and inside of the guide sleeve 55.

Fig. 7A shows the in Fig. 7 shown section of the fuel injection valve 1 in another possible embodiment. The sealing of the guide sleeve 55 to the throttle plate 11 is achieved by an annular surface 81 which is configured on the guide sleeve 55. In the operational state of the fuel injection valve 1, the annular surface 81 with respect to the throttle plate 11 to a pressure corresponding to at least that of the plate assembly. This is achieved in that the annular surface 81 is formed as a small surface 81 and preferably at least approximately corresponds to an outer diameter of the guide sleeve 55. This ensures that axial compressive forces do not unduly reduce the annular surface pressure during operation. Furthermore, with increasing fuel pressure, the pressure on the annular surface 81 is increased, which takes into account the fact that the pressure requirements increase with the pressure. This is achieved by the pressurized throttle plate area on the nozzle side opposite the valve plate side. As a result, the resulting pressure force buckles the throttle plate 11 in the direction of the valve plate 10th

The guide sleeve 55 abuts with its annular surface 81 on a valve plate-side surface 80 of the throttle plate 11. The preferably flat annular surface 81 of the guide sleeve is in this case preferably designed parallel to the preferably flat surface 80 of the throttle plate 11.

The pressure reduction of the guide clearance for the valve pin 26 in the guide sleeve 55 is hereinafter also with reference to the Fig. 8, 9 . 10, 11 further described. Fig. 8 shows a partial representation of the in Fig. 7 shown fuel injection valve 1 of the second embodiment in operation at low pressure. Fig. 9 shows the in Fig. 8 with IX designated section at low pressure. Fig. 10 shows the in Fig. 8 shown section of the fuel injection valve 1 of the second embodiment in operation at high pressure and Fig. 11 shows the in Fig. 10 with XI designated section in operation at high pressure.

At low rail pressures p results in a guide situation in which the guide gap 62 is configured in the ideal case of the gap entrance 63 to the gap exit 64 in cross section in parallel, as in the 8 and 9 is illustrated. This situation arises when the sealing sleeve deformation is still low due to the compressive forces, whereby a laminar flow along the guide gap 62 adjusts with approximately linearly falling pressure curve, as illustrated by the arrows 85. Along the guide sleeve outside of the guide sleeve 55 results in a constant pressure curve, as illustrated by the arrows 86. The leakage amount dQ is then approximately obtained as the product of the rail pressure p and a fractional value with a numerator that is the third power of the gap width s and a denominator that is equal to the length L of the guide sleeve 55. The rail pressure p in this case acts in the high-pressure region and thus, for example, also in the annular gap 50 and the outer annular gap 76.

The management situation with very large rail pressures, in particular with a maximum rail pressure, is based on the 10 and 11 illustrated. In this case, the diameter of the guide sleeve 55 decreases at high rail pressure as a result of the pressure force differences, which increase in the region of the gap outlet 64 in the direction of the throttle plate 11, so that the guide gap 62 at the gap outlet 64 is very small. In this case, the gap width s at the gap exit 64 approaches zero, as shown in FIG Fig. 11 is illustrated. The leakage quantity dQ thereby assumes very small values and is approximately equal to zero. The resulting due to the laminar flow pressure along the guide gap 62 assumes an approximately rectangular course, as illustrated by the arrows 85. Due to the geometric adjustment of the outside diameter, the Inside diameter, a manufacturing clearance and the length L of the guide widening a jam-free guidance can be achieved with minimum leakage amount dQ.

The fuel injection valve can also be configured in one of the following ways and optionally further developed in a suitable manner.

In this regard, a fuel injector 1, in particular an injector for fuel injection systems of air-compressing, self-igniting internal combustion engines, with a control valve 25 and a control chamber 17 is indicated, wherein the control chamber 17 is connected via a drain passage 22 with a valve chamber 24 of the control valve 25, wherein the control valve 25 a Guide sleeve 55 receives in a recess, wherein the guide sleeve is acted upon at least on a part of the circumference with high fuel pressure, wherein a valve pin 26 is guided in the guide sleeve and wherein the valve pin 26 has a valve body arranged in the valve body 27.

A possible development of this fuel injection valve is characterized in that the valve body 27 cooperates on the one hand with a first valve seat surface 37 to a first sealing seat, via which a connection of the valve chamber 24 with a pressure-relieved space 41 is controllable, and that the valve body 27 on the other hand with a second valve surface 46 cooperates to a second sealing seat, via which a connection of the valve chamber 24 with a high pressure passage 12 is controllable.

The invention is not limited to the described embodiments.

Claims (9)

1. Fuel injection valve (1), in particular injector for fuel injection systems of air-compressing, autoignition internal combustion engines, having a control valve (25) and having a control chamber (17), wherein the control chamber (17) is connected via an outflow duct (22) to a valve chamber (24) of the control valve (25), wherein the control valve (25) has a valve pin (26) with a valve body (27) arranged in the valve chamber (24), wherein the valve body (27), at one side, interacts with a first valve seat surface (37) to form a first sealing seat by means of which a connection of the valve chamber (24) to a pressure-relieved chamber (41) can be controlled, and wherein the valve body (27), at the other side, interacts with a second valve seat surface (46) to form a second sealing seat by means of which a connection of the valve chamber (24) to a high-pressure duct (12) can be controlled, and wherein the valve body (27) has a sealing edge (39) assigned to the first valve seat surface (37), and the sealing edge (39) of the valve body (27) interacts with the first valve seat surface (37) to form the first sealing seat, wherein the first valve seat surface (37) is configured as an at least substantially planar first valve seat surface (37) and is oriented at least approximately perpendicular to a valve axis (30) of the control valve (25).
2. Fuel injection valve according to Claim 1,
   characterized
   in that, when the valve body (27) is in a first switching position, the first sealing seat is closed and the second sealing seat is open, in that, when the valve body (27) is in a second switching position, the first sealing seat is open and the second sealing seat is closed, and in that an actuator (28) is provided which serves for adjusting the valve body (27) from the first switching position into the second switching position.
3. Fuel injection valve according to either of Claims 1 and 2,
   characterized
   in that a second valve seat surface (46) is provided, in that the valve body (27) has a sealing surface (48) assigned to the second valve seat surface (46), and in that the sealing surface (48) of the valve body (27) interacts with the second valve seat surface (46) to form the second sealing seat.
4. Fuel injection valve according to Claim 3,
   characterized
   in that a sealing edge (47) is formed on the second valve seat surface (46), and in that the sealing surface (48) of the valve body (27) interacts with the sealing edge (47) of the second valve seat surface (46) to form the second sealing seat,
   and/or
   in that the sealing surface (48) of the valve body (27) is configured as an at least approximately conical sealing surface (48).
5. Fuel injection valve according to Claim 3 or 4,
   characterized
   in that the second valve seat surface (46) is formed on a valve plate (10).
6. Fuel injection valve according to Claim 3 or 4,
   characterized
   in that a guide sleeve (55) is provided, in that the valve pin (26) is guided in the guide sleeve (55), and in that the second valve seat surface (46) is formed on the guide sleeve (55).
7. Fuel injection valve according to Claim 6,
   characterized
   in that a valve plate (10) is provided, in that the valve plate (10) has a recess (32), in that the guide sleeve (55) is arranged in the recess (32) of the valve plate (10), in that a throttle plate (11) is provided which bears against the valve plate (10), in that the guide sleeve (55) has a biting edge (79) assigned to a sealing surface (80) of the throttle plate (11), in that the guide sleeve (55) interacts, by way of its biting edge (79), with the sealing surface (80) of the throttle plate (11), and in that a projecting length of the biting edge (79) in relation to the sealing surface (80) of the throttle plate (11) is predefined.
8. Fuel injection valve according to Claim 6,
   characterized
   in that a valve plate (10) is provided, in that the valve plate (10) has a recess (32), in that the guide sleeve (55) is arranged in the recess (32) of the valve plate (10), in that a throttle plate (11) is provided which bears against the valve plate (10), in that the guide sleeve (55) has an annular surface (81) assigned to a sealing surface (80) of the throttle plate (11), and in that the guide sleeve (55) interacts, by way of its annular surface (81), with the sealing surface (80) of the throttle plate (11).
9. Fuel injection valve according to one of Claims 1 to 8,
   characterized
   in that the valve chamber (24) of the control valve (25) is configured as an at least substantially annular valve chamber (24),
   and/or
   in that a height (32) of the valve chamber (24) is determined at least substantially by an axial spacing (32) between the first sealing seat at the first valve seat surface (37) and the second sealing seat at the second valve seat surface (46).

Images