EP2918817B1 - Fuel injection system - Google Patents

Description

The invention relates to a fuel injection system with a sensor arrangement for measuring physical quantities in the fuel injection system.

State of the art

From the publication DE 10 2011 051 765 A1 a fuel injector of a fuel injection system for injecting fuel into the combustion chamber of an internal combustion engine is known, comprising an injector body or a housing in which a high-pressure bore or a pressure chamber is formed with a longitudinally displaceably arranged nozzle needle, which cooperates with a nozzle needle seat of the housing. Due to the interaction of the nozzle needle with the nozzle needle seat, a fuel flow to at least one injection opening is opened or interrupted. The known fuel injector of a fuel injection system has a control valve for controlling the pressure in a control chamber, whereby the longitudinal movement of the nozzle needle is controlled. For detecting the pressure in the control chamber, the fuel injector has a sensor system or a sensor arrangement which is arranged completely within the fuel injector in a depression, on whose rear side a puncture channel ends at the control chamber. The wall between the puncture channel and depression thereby forms a kind of membrane whose deformation is detected by the sensor arrangement.

The sensor arrangement of the known fuel injector measures the deformation of the pressurized wall between the depression and the puncture channel and thus only indirectly the pressure in the control chamber. In addition, the design of the puncture channel and in particular the membrane-like wall between recess and puncture channel is critical to strength. Measurement accuracy and life of this sensor arrangement are limited. Furthermore, the sensor arrangement is limited to the measurement of the pressure in the control room.

A fuel injection system according to the preamble of claim 1 is also known from EP 2 105 607 A2 known. The sensor arrangement of this fuel injection system detects the pressure in the pressure chamber.

Disclosure of the invention

The fuel injection system according to the invention for injecting fuel into the combustion chamber of an internal combustion engine does not have these disadvantages: In the fuel injection system according to the invention, the service life is not reduced due to the design and arrangement of the sensor arrangement. Furthermore, the sensor arrangement is generally suitable for high pressure areas, that is not limited to the control space of a fuel injector, and measures the physical quantities in the high pressure areas directly. In the exemplary embodiments, it is shown that the sensor arrangement is particularly suitable for the pressure chamber of a fuel injector, the control chamber of a fuel injector, the storage space of a rail and the rail connection bore of a high-pressure pump. However, the invention is not limited to these ranges, but is applicable to all high pressure areas of a fuel injection system, which are preferably separated by a housing wall from a low pressure area and in which physical quantities are to be measured by means of a sensor.

For this purpose, the fuel injection system has a sensor bore formed in a housing, through which a sensor arrangement protrudes into a high pressure area formed in the housing, wherein the sensor arrangement forms the sensor bore closes liquid-tight. The sensor arrangement comprises a sensor arranged in the high-pressure region and two contact wires cast in an electrically non-conductive sheath.

As a result, the physical quantity is measured directly in the high-pressure region. A strength-critical wall or membrane is not formed.

In an advantageous embodiment, the sensor arrangement is pressed into the sensor bore. The high-pressure area is thereby sealed liquid-tight in an easy-to-manufacture design.

In a further advantageous embodiment, the sensor arrangement further comprises an outer sleeve, in which the sheath is cast or pressed. The outer sleeve can be made of a comparatively very strong material, so that a very firm connection between the sensor arrangement and the sensor bore is shown.

Advantageously, the sensor bore and the outer sleeve are conically shaped in the same way, so that a conical compression bandage is formed between them. As a result, high axial forces can be transmitted in the axial direction between the sensor arrangement and the sensor bore or housing.

Advantageously, the conical shape of sensor bore and outer sleeve tapers away from the high-pressure region. Thus, the sensor assembly is pressed into the sensor bore due to the pressure in the high pressure region; a further fixation of the sensor arrangement is not necessary.

In advantageous embodiments, the outer sleeve consists of a metallic material. As a result, the outer sleeve is made very strong; the interference fit to the housing can thus be performed with high surface pressures, so that the connection of the sensor assembly to the housing is particularly liquid-tight. According to the invention, the sheath consists of a glass. Glass combines the properties of very low electrical conductivity (quasi insulator), high pressure resistance and high chemical resistance and is thus particularly well suited for the sheathing.

Advantageously, the materials of first contact wire, second contact wire, sheath and outer sleeve have similar coefficients of thermal expansion, and preferably the coefficients of thermal expansion of two materials in contact with one another do not differ by more than 25%. The smaller the deviation of two materials or components in contact, the lower are the thermal stresses resulting from thermal stresses or changes in existing stresses. Otherwise, both a strength problem and a leak problem may occur. In an advantageous embodiment, the heat transfer coefficient of the outer sleeve differs from that of the housing by not more than 25%.

In a further advantageous embodiment, the high-pressure region is a pressure chamber formed in a fuel injector, in which a nozzle needle is arranged so as to be longitudinally displaceable, wherein the nozzle needle cooperates by its longitudinal movement with a nozzle needle seat and thereby opens and closes at least one injection opening. Thereby, the sensor is arranged directly in the pressure space and can there a physical size of the injected fuel into the combustion chamber, e.g. determine the pressure, and forward a signal from which the pressure or the pressure profile can be determined to a control unit. Thus, the injection characteristic of the fuel injector can be significantly improved detected by a controller and the injection can be controlled accordingly, which increases the efficiency of the entire fuel injection system.

In another advantageous embodiment, the fuel injection system comprises a fuel injector in which a pressure chamber is formed, wherein a nozzle needle is arranged to be longitudinally displaceable in the pressure chamber. The nozzle needle cooperates by its longitudinal movement with a nozzle needle seat and thereby opens and closes at least one injection opening. The nozzle needle limits at its end opposite the nozzle needle seat a control chamber and the longitudinal movement of the nozzle needle is controlled by the pressure in the control chamber. In this embodiment, the control room is the high pressure area. About the determination of a physical quantity in the Control space, such as the pressure, the characteristic of a control valve, via which the fuel is controlled in the control room, determined by a control unit and can be used to control the injection process.

In a further advantageous embodiment, the fuel injection system comprises a rail, in which a storage space for fuel under high pressure is formed, wherein the rail has a first connection to a high-pressure pump and at least one second connection to at least one fuel injector. In this embodiment, the storage space is the high pressure area. For example, in this embodiment, the temperature and / or pressure in the storage space can be measured and recorded by a controller. The values thus recorded or their changes allow conclusions to be drawn as to the fuel injection system's efficiency or its change over the service life.

In another advantageous embodiment, the fuel injection system comprises a high-pressure pump with a cylinder head, which comprises the housing. In the housing, a compression space for compressing fuel is formed. From the compression space, a rail connection bore formed in the housing branches off and opens at least indirectly into a rail. In this embodiment, the rail connection bore is the high pressure area. Physical quantities, e.g. Pressure, temperature and acceleration can be measured with the sensor of this design and processed in a control unit. For example, a kind of shaking load, resulting from vibrations, can be determined for the cylinder head via the measurement of the acceleration. Such shaking loads can adversely affect the operation of the high pressure pump and thus adversely affect the efficiency of the fuel injection system. Especially for diagnostic purposes recording the shaking loads may be beneficial.

In a further advantageous embodiment, the first contact wire and the second contact wire are electrically insulated from each other embedded in the sheath and protrude high pressure area side only with their respective contact wire ends of the sheath out. This minimizes electrical energy losses.

Advantageously, the sensor is electrically connected to the first contact wire end by a first solder contact and to the second contact wire end by a second solder contact. The electrical connections of the sensor to the contact wires are thereby carried out in a simple yet reliable form. In alternative embodiments, the sensor is connected to the first contact wire end and the second contact wire end via welding contacts, electrically conductive adhesive bonds or mechanical crimp connections.

In advantageous embodiments, the sensor is a pressure sensor. The pressure in the fuel injector is the most important evaluation variable for many applications. For example, can be calculated well over the injection duration and the pressure in the pressure chamber of a fuel injector, the injected fuel amount. This makes it possible to adapt the actual fuel quantity to the desired fuel quantity by changing the injection duration; thus, a more robust fuel injector injection characteristic is achieved, and the entire fuel injection system is more reliable and efficient over the life of the fuel injector.

Another application is a pressure sensor for the rail. The pressure sensor supplies a signal to the control unit, by means of which a pressure profile in the rail can be recorded over a long time. By means of this pressure curve can be determined, for example, how a maximum pressure in the rail changes over the life of the fuel injection system. Such a change in the maximum pressure may e.g. resulting from the wear of a pressure relief valve of the rail, or even from the change in the spring stiffness of the pressure relief valve. With this knowledge countermeasures can be taken in time.

In other advantageous embodiments, the sensor is a temperature sensor. The temperature is another important physical quantity to represent the injection characteristic of a fuel injector of the fuel injection system.

In a particularly advantageous embodiment, the sensor is both a pressure and a temperature sensor. As a result, the signals of two particularly important physical variables of a high-pressure region can be sent to a control unit for evaluation and further processing. In other advantageous embodiments, other variables such as inclination, movement and acceleration are also measured with the same sensor.

In advantageous embodiments, a low-pressure region is formed on the side of the sensor bore opposite the high-pressure region. As a result, the volume of the high-pressure region is limited and is hardly influenced by the manufacturing tolerances of the sensor arrangement. In addition, the further contacting of the two contact wires to run the controller easier.

drawings

• Fig.1 shows schematically a fuel injector of a fuel injection system according to the invention in longitudinal section, wherein only the essential areas are shown.
• Fig.2 schematically shows a further embodiment of a fuel injector of the fuel injection system according to the invention in longitudinal section, wherein also here only the essential areas are shown.
• Figure 3 shows schematically an embodiment of a rail of the fuel injection system according to the invention in longitudinal section, wherein also here only the essential areas are shown.
• Figure 4 shows schematically an embodiment of a high-pressure pump of the fuel injection system according to the invention in longitudinal section, wherein also here only the essential areas are shown.
• Figure 5 shows in cross section a further embodiment of a sensor arrangement of the fuel injector according to the invention.

description

Fig.1 shows a longitudinal section of a fuel injector 101 for a fuel injection system 100, wherein only the essential parts for the present invention are shown. The fuel injector 101 serves to inject high-pressure fuel, which can be supplied for example from a so-called common rail or rail or from an internal high-pressure accumulator of the fuel injector 101, into a combustion chamber of an internal combustion engine. Within the fuel injection system 100, the fuel is compressed in a high-pressure pump and fed from the latter to the rail.

The fuel injector 101 has a pressure chamber 21 formed in a housing 20, in which a nozzle needle 22 is arranged to be longitudinally displaceable. The pressure chamber 21 is connected by a high-pressure passage, not shown, with the high-pressure accumulator or with the rail and thereby filled with fuel. As a result of its longitudinal movement, the nozzle needle 22 cooperates with a nozzle needle seat 23 formed on the housing 20 and thereby opens and closes at least one injection opening 24 formed in the housing 20 for injecting fuel under high pressure into the combustion chamber of an internal combustion engine. On the nozzle needle 22, a pressure shoulder 22a is formed, at which, due to the high pressure in the pressure space 21, a hydraulically opening, i. force directed away from the nozzle needle seat 23 acts.

The housing 20 is clamped at the nozzle needle seat end remote from a valve plate 29 by a clamping device, not shown, so that the valve plate 29 limits the pressure chamber 21. Between the nozzle needle 22, the valve plate 29 and a sleeve 28 in which the nozzle needle seat facing away from the end of the nozzle needle 22 is guided longitudinally movable, a control chamber 25 is formed, which is connected by a formed in the sleeve 28 inlet throttle 28a to the pressure chamber 21. The sleeve 28 is pressed by a nozzle needle 22 surrounding the nozzle spring 31 against the valve plate 29. At the same time exercises the nozzle spring 31 a closing force on the nozzle needle 22, since it is supported on a shoulder 22b of the nozzle needle 22 under compressive prestress.

The pressure in the control chamber 25, which also exerts a closing force on the nozzle needle 22, is controlled by a control valve, not shown, which opens and closes an outlet throttle 29a formed in the valve plate 29, so that the outlet throttle 29a the control chamber 25 with a not shown Low pressure space connects or the connection is interrupted.

A sensor arrangement 10 is pressed into a sensor bore 11, which is formed in the housing 20 and extends radially outward, such that a sensor 3 of the sensor arrangement 10 is arranged in the pressure chamber 21. The sensor assembly 10 comprises in addition to the sensor 3, two contact wires 1 and 2, which are cast in an electrically non-conductive sheath 7, and an outer sleeve 8, in which the sheath 7 is cast or pressed. The two contact wires 1 and 2 are electrically conductively connected to the sensor 3, for example via solder contacts, but are electrically isolated from each other by the sheath 7.

The sensor arrangement 10 completely fills the sensor bore 11 and seals it in a liquid-tight manner, so that the pressure chamber 21 is sealed off from the end of the sensor arrangement 11 opposite the pressure chamber 21, against which low pressure or atmospheric pressure is applied. The two contact wires 1 and 2 can be cast in the low-pressure region with plastic in order to continue the electrical insulation of the contact wires from each other outside the sensor arrangement 10.

Depending on the embodiment, the sensor 3 can provide a signal from which, for example, pressure and / or temperature of the fuel in the pressure chamber 21 can be determined. In addition, it is also conceivable, for example, to determine the acceleration by the sensor 3 in order to determine a shaking load therefrom. This data can be processed in a control unit. For example, based on the pressure curve in the pressure chamber 21, the injection characteristic of the fuel injector 101 can be changed for subsequent injections by the control valve of Control unit is controlled accordingly changed, whereby the entire fuel injection system 100 is more efficient.

Fig.2 shows schematically a further embodiment of a fuel injector 101 of the fuel injection system 100 according to the invention in longitudinal section, wherein also only the essential areas are shown.

Like in the Fig.1 also shows the embodiment of the fuel injector 101 of Fig.2 formed in the housing 20 pressure chamber 21, in which the nozzle needle 22 is longitudinally displaceable and cooperates with the housing 20 formed on the nozzle needle seat 23 and thereby at least one housing 20 formed in the injection port 24 for injecting fuel under high pressure in the combustion chamber of an internal combustion engine opens and close. The pressure chamber 21 is connected by a high-pressure passage 35 leading through the housing 20 to the high-pressure accumulator or to the rail. On the nozzle needle 22, a pressure shoulder 22a is formed, on which acts due to the high pressure in the pressure chamber 21, a hydraulically opening, ie away from the nozzle needle seat 23 force.

• Die auf die Düsennadel 22 schließend wirkende Düsenfeder 31 ist im Steuerraum 25 angeordnet und die Düsennadel 22 ist im Gehäuse 20 eng geführt. Dadurch entfällt in diesem Ausführungsbeispiel die Hülse des Ausführungsbeispiels der Fig.1 . Auf einer dem Brennraum abgewandten Stirnseite 20b des Gehäuses 20 ist eine Ausnehmung 20a ausgebildet, die sich an den Steuerraum 25 anschließt. Die Ventilplatte 29 ist in die Ausnehmung 20a eingepresst bzw. eingelegt und mit einer nicht dargestellten Spannvorrichtung mit dem Gehäuse 20 flüssigkeitsdicht verspannt.

The arrangement of the following features of Fig.2 deviates from the embodiment of Fig.1 from:

• The closing of the nozzle needle 22 acting nozzle spring 31 is disposed in the control chamber 25 and the nozzle needle 22 is tightly guided in the housing 20. This eliminates in this embodiment, the sleeve of the embodiment of Fig.1 , On a side facing away from the combustion chamber 20b of the housing 20, a recess 20a is formed, which adjoins the control chamber 25. The valve plate 29 is pressed or inserted into the recess 20a and clamped liquid-tight manner with a clamping device, not shown, with the housing 20.

In the valve plate 29, the inlet throttle 28a and the outlet throttle 29a for controlling the pressure in the control chamber 25 are arranged. The inlet throttle 28a is permanently connected to the high-pressure accumulator or rail and the Outflow throttle 29a connected via a control valve, not shown, switchable with a low pressure chamber, not shown.

The sensor arrangement 10 is arranged so that the sensor 3 projects into the control space 25. Due to the recess 20a, the sensor bore 11 in this embodiment can be obliquely passed through the housing 20 on the valve plate 29 so that it exits at the end face 20b. A contacting of the two contact wires 1 and 2 of the sensor assembly 10 for the continuation of the electrical conduction is effected in the region of the end face 20b and not radially outside of the housing 20 as in the embodiment of Fig.1 ,

Of course, in other embodiments, the sensor bore 11 may also extend radially outward. The contacting of the two contact wires 1 and 2, however, then takes place radially outside the housing 20 and not on the end face 20b.

• Die Sensoranordnung 10 umfasst neben dem Sensor 3 die beiden Kontaktdrähte 1 und 2, die in die elektrisch nicht leitende Ummantelung 7 aus Glas eingegossen sind, und die Außenhülse 8, vorzugsweise aus Metall, in die die Ummantelung 7 eingegossen oder eingepresst ist. Die beiden Kontaktdrähte 1 und 2 sind mit dem Sensor 3 elektrisch leitend verbunden.

The sensor assembly 10 itself is in the embodiment of Fig.2 however, similar to the previous embodiment of the Fig.1 run:

• The sensor assembly 10 comprises in addition to the sensor 3, the two contact wires 1 and 2, which are cast in the electrically non-conductive jacket 7 made of glass, and the outer sleeve 8, preferably made of metal, in which the sheath 7 is cast or pressed. The two contact wires 1 and 2 are electrically connected to the sensor 3.

Figure 3 1 schematically shows an embodiment of a rail 102 of the fuel injection system 100 according to the invention in longitudinal section, the sensor arrangement 10 being arranged in the rail 102 of the fuel injection system 100. The rail 102 comprises a housing 20 in which a storage space 41 for storing high-pressure fuel is formed. The housing 20 has a first port 45, via which the storage space 41 is at least indirectly connected to a high-pressure pump, not shown, and is thus filled with the fuel pumped by the high-pressure pump. Furthermore, the housing 20 at least a second port 46, via which the storage space 41 is at least indirectly connected to at least one fuel injector, and via which the rail 102 feeds the at least one fuel injector with fuel under high pressure.

In order not to exceed a maximum pressure in the storage space 41, a pressure limiting valve 48 is arranged in the housing 20 of the rail 102, which connects when exceeding the maximum pressure in the storage space 41 with a low pressure region, not shown, and closes this connection again when the pressure in the storage space 41 falls below the maximum pressure.

The sensor arrangement 10 is arranged in a sensor bore 11 formed in the housing 20 so that the sensor 3 projects into the storage space 41. The sensor arrangement 10 itself is analogous to the preceding embodiments, with two contact wires 1 and 2, which are cast in the electrically non-conductive sheath 7, and with the outer sleeve 8, in which the sheath 7 is cast or pressed. The two contact wires 1 and 2 are electrically connected to the sensor 3.

Figure 4 shows an embodiment of a cylinder head 104 of a high-pressure pump 103 of a fuel injection system 100 according to the invention in longitudinal section, wherein also here only the essential areas are shown.

The cylinder head 104 includes a housing 20 in which a compression space 62 is formed. The compression chamber 62 is filled via a suction valve, not shown, which is arranged in a formed on the housing 20 Saugventilanschluss 64, with low-pressure fuel. A likewise formed in the housing 20 piston bore 61 opens into the compression chamber 62. In the piston bore 61, an unillustrated pump piston is guided, which changes the volume of the compression chamber 62 by its upward and downward movement and thereby compresses the fuel therein.

A trained in the housing 20 Rail connection bore 60 leads away from the compression space 62 and opens at least indirectly in a not shown rail. For this purpose, a rail connection 63 is formed on the housing 20, to which a high-pressure connection (not shown) is attached. In the rail connection bore 60, a non-illustrated check valve is arranged, which connects the compression chamber 62 with the rail when a limit pressure in the compression space 62 is exceeded, and then flow the compressed fuel to the rail; this happens when the pump piston is on its way to its top dead center. The check valve closes the connection to the rail when the limit pressure in the compression chamber 62 is exceeded; this happens when the pump piston moves away from its top dead center.

The sensor arrangement 10 is arranged in a sensor bore 11 formed in the housing 20 so that the sensor 3 projects into the rail connection bore 60. In other embodiments, the sensor 3 protrudes into the compression space 62. The sensor arrangement 10 itself is again designed analogous to the preceding embodiments, with two contact wires 1 and 2, which are cast in the electrically non-conductive sheath 7, and with the outer sleeve 8, in the sheath 7 is poured or pressed. The two contact wires 1 and 2 are electrically connected to the sensor 3.

Figure 5 shows in cross-section an embodiment of the sensor arrangement 10 of a further fuel injection system 100 according to the invention and can be used as an alternative to all embodiments presented above. The sensor assembly 10 is in the radially outwardly or obliquely extending sensor bore 11 which is formed in the housing 20, pressed: the press connection is a conical interference fit in which both the outer sleeve 8 and the sensor bore 11 are conically shaped in the same way, namely to rejuvenate to the outside. The sensor 3 is arranged in the high-pressure region, for example pressure chamber, control chamber, storage chamber, compression chamber or rail connection bore; As a result, a force directed outwardly from the high-pressure region acts on the entire sensor arrangement 10 and thus presses the sensor arrangement 10 on the outer sleeve 8 into the "conical seat". the conical sensor bore 11. The assembly of the sensor assembly 10 is carried out in this embodiment by the high-pressure region inside the housing 20. Advantageously, the cone angle of the sensor bore 11 and outer sleeve 8 are the same size.

In the high-pressure region, the two contact wire ends 1a and 2a of the two contact wires 1 and 2 open out of the casing 7 and are electrically conductively connected to the sensor 3 via a respective soldering contact 4 or 5. Alternatively, other electrically conductive connection types can be selected. The sheath 7 is enclosed in the outer sleeve 8 having a greater strength. In this case, the outer sleeve 8 of electrically conductive material, e.g. Be made steel, since the two contact wires within the sensor assembly 10 are electrically insulated by the sheath 7.

On the low pressure side of the sensor bore 11, the two contact wires 1 and 2 are outside the sensor assembly 10 with a potting compound 35, preferably made of plastic, fixed to the electrical insulation of the contact wires 1 and 2 from each other outside the sensor assembly 10.

Due to the temperature variations prevailing in the fuel injection system 100 over the lifetime, the materials of the sensor assembly 10 and the housing 20 are preferably selected such that the thermal expansion coefficients of two mutually contacting materials do not differ by more than 25%, not too large to generate thermal stresses. Otherwise, on the one hand there is the risk of excessive component stresses, on the other hand, however, the tightness, both within the sensor assembly 10 and between the sensor assembly 10 and housing 20, can be reduced if the temperatures occurring reduce the contact pressures between two components.

The sensors 3 of the illustrated embodiments may be sensors for different physical quantities, but preferably sensors for temperature and especially pressure. There are also sensors 3 used, the capture multiple physical quantities simultaneously, such as pressure and temperature. Furthermore, sensors for acceleration, movement and inclination can be used, especially if they can measure temperature and / or pressure at the same time. Of these variables, especially the pressure curve in the pressure chamber 21 can be used well to describe the characteristics of the fuel injection system 100, for example for the injection characteristic of the fuel injector 101 or for the pressure pulsations in the rail 102 and in the high-pressure pump 103.

The two contact wires 1 and 2 are at least indirectly connected to a control unit, not shown, so that the course of the physical quantity, e.g. the pressure can be sufficiently recorded and processed. For example, the injection characteristic of the fuel injector 101 can thus be detected, but also changed on the basis of the measured course, e.g. by a change in the control of the control valve to directly influence the pressure profile in the control chamber 25 and thus also, for example. the amount of fuel injected into the combustion chamber of the internal combustion engine.

Claims (14)

1. Fuel injection system (100) for injecting fuel into a combustion chamber of an internal combustion engine, having a housing (20) and having a sensor bore (11) formed in said housing, through which sensor bore a sensor arrangement (10) projects into a high-pressure region formed in the housing (20), wherein the sensor arrangement (10) closes off the sensor bore (11) in liquid-tight fashion, wherein the sensor arrangement (10) comprises a sensor (3) arranged in the high-pressure region and two contact wires (1, 2) cast into an electrically non-conductive encapsulation (7), characterized in that the encapsulation (7) is composed of a glass.
2. Fuel injection system (100) according to Claim 1, characterized in that the sensor arrangement (10) is pressed into the sensor bore (11).
3. Fuel injection system (100) according to Claim 1 or 2, characterized in that the sensor arrangement (10) furthermore comprises an outer sleeve (8) into which the encapsulation (7) is cast or pressed.
4. Fuel injection system (100) according to Claim 3, characterized in that the sensor bore (11) and the outer sleeve (8) are of similar conical form such that a conical interference fit is formed between them.
5. Fuel injection system (100) according to Claim 4, characterized in that the conical shape of sensor bore (11) and outer sleeve (8) tapers away from the high-pressure region.
6. Fuel injection system (100) according to one of Claims 3 to 5, characterized in that the outer sleeve (8) is composed of a metallic material.
7. Fuel injection system (100) according to one of Claims 3 to 6, characterized in that the materials of first contact wire (1), second contact wire (2), encapsulation (7) and outer sleeve (8) have similar coefficients of thermal expansion, wherein preferably, the coefficients of thermal expansion of two materials that are in contact with one another differ from one another by no more than 25%.
8. Fuel injection system (100) according to one of the preceding claims, characterized in that the high-pressure region is a pressure chamber (21) which is formed in a fuel injector (101) and in which a nozzle needle (22) is arranged in longitudinally displaceable fashion, wherein the nozzle needle (22), by means of its longitudinal movement, interacts with a nozzle needle seat (23) and thereby opens and closes at least one injection opening (24).
9. Fuel injection system (100) according to one of Claims 1 to 7, characterized in that the fuel injection system (100) comprises a fuel injector (101) in which a pressure chamber (21) is formed, wherein a nozzle needle (22) is arranged in longitudinally displaceable fashion in the pressure chamber (21), wherein the nozzle needle (22), by means of its longitudinal movement, interacts with a nozzle needle seat (23) and thereby opens and closes at least one injection opening (24), and the nozzle needle (22), at its end situated opposite the nozzle needle seat (23), delimits a control chamber (25), and the longitudinal movement of the nozzle needle (22) is controlled by the pressure in the control chamber (25), wherein the control chamber (25) is the high-pressure region.
10. Fuel injection system (100) according to one of Claims 1 to 7, characterized in that the fuel injection system (100) comprises a rail (102) in which an accumulator chamber (41) for highly pressurized fuel is formed, wherein the rail (102) has a first connector (45) to a high-pressure pump (103) and has at least one second connector (46) to at least one fuel injector (101), wherein the accumulator chamber (41) is the high-pressure region.
11. Fuel injection system (100) according to one of Claims 1 to 7, characterized in that the fuel injection system (100) comprises a high-pressure pump (103), having a cylinder head (104) which comprises the housing (20) and in which there is formed a pressurization chamber (62) for the pressurization of fuel, wherein a rail connector bore (60) formed in the housing (20) branches off from the pressurization chamber (62) and opens at least indirectly into a rail, wherein the high-pressure region is the rail connector bore (60).
12. Fuel injection system (100) according to one of the preceding claims, characterized in that the first contact wire (1) and the second contact wire (2) are embedded in the encapsulation (7) so as to be electrically insulated with respect to one another and, at the high-pressure region side, project out of the encapsulation (7) only by means of their respective contact wire ends (1a and 2a), wherein the sensor (3) is electrically connected by means of a first soldered contact (4) to the first contact wire end (1a) and by means of a second soldered contact (5) to the second contact wire end (2a).
13. Fuel injection system (100) according to one of the preceding claims, characterized in that the sensor (3) is a pressure sensor and/or a temperature sensor.
14. Fuel injection system (100) according to one of the preceding claims, characterized in that a low-pressure region is formed on that side of the sensor bore (11) which is situated opposite the high-pressure region.

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