DE102015205671A1 - Brennraumdruckaufnehmer, internal combustion engine and method for measuring a combustion chamber pressure in a combustion chamber of an internal combustion engine - Google Patents

Abstract

The invention relates to a combustion chamber pressure sensor (21) for measuring a combustion chamber pressure in a combustion chamber of an internal combustion engine, which comprises a sensor element (10) which converts a pressure (p) acting on the sensor element (10) into an electrically measurable variable. The sensor element (10) is designed as an electrically conductive powder which undergoes a change in its electrical resistance (R) when the pressure (p) on the sensor element (10) changes, and the sensor element (10) is thus located within a pressure tube (8) arranged that a change of the pressure acting on the pressure tube (8) combustion chamber pressure causes a change of the pressure acting on the sensor element (10) pressure (p). The invention also relates to an internal combustion engine which comprises at least one combustion chamber pressure sensor (21, 22, 23, 24) according to the invention. The invention further relates to a method for measuring a combustion chamber pressure in a combustion chamber of an internal combustion engine, wherein an electrical resistance (R) of a sensor element (10) is measured, wherein the sensor element (10) is designed as an electrically conductive powder, which in a change of the sensor element (10) acting pressure (p) undergoes a change in its electrical resistance (R), and wherein the sensor element (10) is arranged within such a projecting into the combustion chamber pressure tube (8) that a change of the pressure tube ( 8) acting combustion chamber pressure causes a change in the pressure acting on the sensor element (10) pressure (p).

Description

The invention relates to a combustion chamber pressure sensor for measuring a combustion chamber pressure in a combustion chamber of an internal combustion engine, which comprises a sensor element which converts a pressure acting on the sensor element into an electrically measurable variable. The invention further relates to an internal combustion engine comprising a combustion chamber pressure sensor according to the invention. The invention also relates to a method for measuring a combustion chamber pressure in a combustion chamber of an internal combustion engine.

State of the art

Due to increasingly stringent legislation on fuel consumption and the resulting pollutant emissions from internal combustion engines, especially in the automotive sector, further developments of the combustion control and the associated control components are necessary. As a decisive factor of combustion to be optimized, combustion chamber pressure has recently been identified which plays a crucial role in achieving optimum combustion in a combustion chamber, especially self-igniting internal combustion engines.

In order to measure the combustion chamber pressure of an internal combustion engine, for example, combustion chamber pressure sensors are provided in the combustion chamber of the internal combustion engine. In particular, there is a need for large-volume combustion chamber pressure sensors, both for gasoline engines and for diesel engines. For novel engine concepts, such as self-igniting gasoline engines (HCCI engines), combustion chamber pressure sensors are desirable.

A device for detecting a combustion chamber pressure in a combustion chamber of an internal combustion engine is, for example, in the document DE 10 2010 038 798 A1 disclosed. The device comprises a transducer element, in particular a piezoelectric element, which is acted upon by a pressure transducer. The pressure sensor protrudes into the combustion chamber and exerts a force on the transducer element as a function of the pressure prevailing in the combustion chamber.

From the publication EP 1 517 086 B1 is known a Druckmessglühkerze for a diesel engine. The pressure measuring glow plug comprises a plug body with a heating rod for heating the combustion chamber, and a pressure sensor for measuring a combustion chamber pressure in the combustion chamber. The pressure sensor is arranged at a location which is located outside of the combustion chamber when mounted in the diesel engine Druckmessglühkerze. The heating rod of the Druckmessglühkerze is movably mounted along its longitudinal axis and is pressed depending on the pressure prevailing in the combustion chamber pressure on the pressure sensor. The heating element thus transfers the combustion chamber pressure mechanically to the pressure sensor.

A glow plug with integrated pressure measurement for a combustion chamber pressure of an internal combustion engine is also from the document EP 1 500 879 B1 known. The glow plug comprises a heating and control coil arranged in an incandescent tube for heating the combustion chamber, and a pressure measuring device for measuring the combustion chamber pressure in the combustion chamber. The pressure measuring device has a pressure sensor, which is located outside of the combustion chamber when mounted in the internal combustion engine Druckmessglühkerze. By means of a pressure channel, which is formed from a groove, the pressure transducer is connected to the combustion chamber.

Disclosure of the invention

A combustion chamber pressure sensor for measuring a combustion chamber pressure in a combustion chamber of an internal combustion engine is proposed, which comprises a sensor element which converts a pressure acting on the sensor element into an electrically measurable variable.

According to the invention, the sensor element is embodied as an electrically conductive powder, which undergoes a change in its electrical resistance when the pressure acting on the sensor element changes, and the sensor element is arranged within a pressure tube such that a change in the combustion chamber pressure acting on the pressure tube results in a change in the pressure on the sensor element acting pressure causes. By such a change of the pressure acting on the sensor element, the electrical resistance of the sensor element changes.

Preferably, the pressure tube is electrically and mechanically connected to a housing having an external thread. Thus, the Brennraumdruckaufnehmer by means of the external thread in a bore in the internal combustion engine can be screwed, which has a corresponding internal thread. In addition, there is thus an electrical connection between the pressure tube and the internal combustion engine, which can be used to measure the resistance of the sensor element.

Preferably, the pressure tube is at least approximately hollow cylindrical, and on a Front side, the pressure tube is closed with a bottom.

According to an advantageous embodiment of the invention, a central electrode is provided, which projects from the side facing away from the bottom into the pressure tube.

The middle electrode extends advantageously up to the sensor element, which is arranged within the pressure tube. The center electrode is an electrical connection to the sensor element, which can be used to measure the resistance of the sensor element.

According to an advantageous embodiment of the invention, an insulating layer is applied to an outer circumferential surface of the center electrode, which preferably extends at least approximately over the entire lateral surface of the center electrode.

According to a further advantageous embodiment of the invention, at least partially a, preferably thin, insulating layer is provided on an inner circumferential surface of the pressure tube.

The sensor element is advantageous at the bottom of the pressure tube, ie in a region in which no insulating layer is provided. As a result, the sensor element constantly has an electrical connection to the bottom of the pressure tube.

According to an advantageous embodiment of the invention, an insulating material is additionally provided within the pressure tube, which is designed as an electrically insulating powder.

Further, an internal combustion engine is proposed which comprises at least one Brennraumdruckaufnehmer invention.

Furthermore, a method for measuring a combustion chamber pressure in a combustion chamber of an internal combustion engine is proposed. In this case, an electrical resistance of a sensor element is measured, wherein the sensor element is designed as an electrically conductive powder, which undergoes a change in its electrical resistance upon a change in the pressure acting on the sensor element, and wherein the sensor element arranged within such a projecting into the combustion chamber pressure tube is that a change in the combustion chamber pressure acting on the pressure tube causes a change in the pressure acting on the sensor element pressure. By such a change of the pressure acting on the sensor element, the electrical resistance of the sensor element changes.

Advantages of the invention

The inventive arrangement of the sensor element within the pressure tube, which can also act as a glow tube, the sensor element is located in the internal combustion engine mounted Brennraumdruckaufnehmer within the combustion chamber, and thus closer to the size to be measured. As a result, pressure measurement with increased speed is possible and also relatively rapidly changing pressures that are common in a combustion chamber of an internal combustion engine can be measured.

The design of the sensor element as an electrically conductive powder allows a relatively simple adaptation to the combustion chamber pressure. In particular, the relationship between pressure and resistance of the sensor element embodied as an electrically conductive powder follows a known curve and depends in particular on a pre-compression of the powder and on the material used for the powder.

The Brennraumdruckaufnehmer can also be combined with a glow plug, that is, the Brennraumdruckaufnehmer can also be used to heat the combustion chamber. In this case, the pressure tube acts as a glow tube and the sensor element, which is designed as an electrically conductive powder acts as a heating material. During a current flow, the powder is then heated, which heats the glow tube, which then delivers the heat to the combustion chamber.

An insulating layer provided within the pressure tube prevents uncontrolled flow of current from the center electrode through the sensor element to the pressure tube.

Brief description of the drawings

Embodiments of the invention will be explained in more detail with reference to the drawings and the description below.

Show it:

1 a longitudinal section through a Brennraumdruckaufnehmer according to a first embodiment,

2 a qualitative representation of the relationship between the pressure acting on a sensor element and the electrical resistance of the sensor element,

3 a longitudinal section through a combustion chamber pressure transducer according to a second embodiment,

4 a longitudinal section through a Brennraumdruckaufnehmer according to a third embodiment,

5 a longitudinal section through a combustion chamber pressure transducer according to a fourth embodiment,

6 a longitudinal section through a Brennraumdruckaufnehmer according to a fifth embodiment and

7 a longitudinal section through a Brennraumdruckaufnehmer according to a sixth embodiment.

Embodiments of the invention

In 1 is a longitudinal section through a combustion chamber pressure transducer 21 shown according to a first embodiment. The combustion chamber pressure transducer 21 According to the first embodiment is used to measure a combustion chamber pressure in a combustion chamber of an internal combustion engine.

The combustion chamber pressure transducer 21 According to the first embodiment, a housing comprises 6 with an external thread. By means of the external thread is the combustion chamber pressure transducer 21 according to the first embodiment screwed into a thread in a bore in the internal combustion engine.

The housing 6 is formed approximately hollow cylindrical. An electrically conductive connection bolt 1 protrudes through an end face in the housing 6 into it. The outer diameter of the connecting bolt 1 is less than the inner diameter of the housing 6 , In the radial direction between the connecting bolt 1 and the housing 6 is a housing seal 4 intended. On the front of the case 6 , on which the connecting bolt 1 protrudes, is also an insulating 3 on. On the case 6 opposite side of the insulating 3 is a connection seal 2 intended.

A pressure tube 8th , which is also formed as a hollow cylinder, protrudes from the opposite end face into the housing 6 into it. The outer diameter of the pressure tube 8th corresponds approximately to the inner diameter of the housing 6 , The pressure tube 8th thus lies on the inner wall of the housing 6 at. At the housing 6 opposite end of the pressure tube 8th is this with a floor 15 locked.

Inside the pressure tube 8th is a center electrode 9 provided, which is approximately rod-shaped or cylindrical. The middle electrode 9 is also electrically conductive and is connected to the connecting bolt 1 connected. The center electrode 9 has an outer diameter which is smaller than the inner diameter of the pressure tube 8th , In the area of the connection point between the connecting bolt 1 and the center electrode 9 is a sensor element seal 5 provided, which the connecting bolt 1 and the center electrode 9 surrounds, and which on the inner wall of the pressure tube 8th is applied.

The pressure tube 8th is at his the housing 6 opposite end with a sensor element 10 filled. The sensor element 10 is designed as an electrically conductive powder. In particular, the sensor element comprises 10 a mixture of relatively low electrical resistance powder and relatively high electrical resistance powder. In the case of the powder of the sensor element 10 with relatively high electrical resistance is, for example, MgO. In the case of the powder of the sensor element 10 with relatively low electrical resistance are, for example, WC, intermetallic phases, oxide ceramics, non-oxide ceramics, carbon modifications, metals, especially refractory metals, or semiconductors.

When changing the on the sensor element 10 acting pressure p is a change in the electrical resistance R of the sensor element 10 , The sensor element 10 surrounds the center electrode 9 concentric.

In the remaining interior of the pressure tube 8th is an insulating material 7 intended. The insulating material 7 is located primarily in the area of the pressure tube 8th which is inside the housing 6 located. The insulating material 7 In the present case, it is also embodied as a powder, in particular as an electrically non-conductive or as an insulating powder. In the powder of the insulating material 7 For example, it is MgO.

The center electrode 9 extends from the terminal bolt 1 towards the ground 15 of the pressure tube 8th to. A front page 13 the center electrode 9 dives into the sensor element 10 one and is only slightly off the ground 15 of the pressure tube 8th spaced.

The combustion chamber pressure transducer 21 According to the first embodiment is, as already mentioned, arranged in a combustion chamber of an internal combustion engine. This means, in particular, the pressure tube 8th protrudes into the combustion chamber of the internal combustion engine.

A combustion chamber pressure prevailing inside the combustion chamber of the internal combustion engine acts on the pressure pipe 8th , The pressure tube 8th gives the recorded combustion chamber pressure on the sensor element located in the interior 10 further. The sensor element 10 , which is designed as an electrically conductive powder, changes due to the applied pressure p its electrical resistance R.

The relationship between the on the sensor element 10 acting pressure p and the electrical resistance R of the sensor element 10 is in 2 presented qualitatively. The pressure p is plotted on the X axis and the resistance R on the Y axis 2 The diagram shown comprises three areas, namely a first area 31 , a second area 32 , and a third area 33 ,

In the first area 31 is the sensor element 10 under a relatively low pressure p. The powder is only slightly compressed and there are no continuous guide paths between the individual powder grains. The proportion of conductive particles in the powder mixture of the sensor element 10 but is so high that can form electrically conductive paths in a further compression of the powder. Increasing the pressure p leads to the formation of conductive paths and the resistance R of the sensor element 10 sinks.

In the second area 32 stands the powder of the sensor element 10 under a higher pressure p than in the first range 31 , The powder is more compressed than in the first area 31 , and there are single continuous guide paths between the particles of the powder. As the pressure p is further increased, additional new conductive paths are formed within the powder mixture, and as a result, the resistance R of the sensor element is reduced 10 with further increasing pressure p.

In the third area 33 is the powder of the sensor element 10 compressed even further. The powder is compressed to a practically maximum possible density. This means that the particles are at most close to each other and there are several Leitpfade between the particles of the powder mixture. In a further increase of the pressure p, the contact surfaces between the individual conductive particles of the powder are increased by an elastic deformation of the same. In this way, the abutting surface of the powder particles increases, and as a result, the electrical resistance R of the sensor element 10 even further downsized.

The sensitivity of the sensor element 10 is in operation in the third area 33 in particular dependent on the moduli of elasticity of the particles. For a measurement of relatively small pressures p, a powder mixture is to be provided whose particles have a relatively low modulus of elasticity. For a measurement of relatively high pressures, a powder mixture is to be provided whose particles have a relatively high modulus of elasticity.

A longitudinal section through a combustion chamber pressure transducer 22 according to a second embodiment is in 3 shown. The combustion chamber pressure transducer 22 according to the second embodiment is similar to the Brennraumdruckaufnehmer 21 according to the first embodiment, which is why only the differences are discussed here.

The inner lateral surface of the pressure tube 8th is almost complete with an insulating layer 12 overdrawn. Only the floor 15 of the pressure tube 8th is free of the insulating layer 12 , The sensor element 10 is located near the ground 15 of the pressure tube 8th and slightly protrudes from the ground 15 of the pressure tube 8th away in the pressure tube 8th into it. The sensor element 10 lies also on the side of the insulating layer 12 at.

Subsequently to the sensor element 10 is a lead material 17 provided, which is a major part of the pressure tube 8th fills. The center electrode 9 protrudes into the guide material 17 into it. The front side 13 the center electrode 9 However, in the present case is significantly further from the ground 15 of the pressure tube 8th removed than with the combustion chamber pressure transducer 21 according to the first embodiment. In particular, the center electrode emerges 9 not in the sensor element 10 one.

The guide material 17 In the present case, a powder pack made of an electrically conductive powder has a relatively low electrical resistance. Also the sensor element 10 is an electrically conductive powder, the sensor element 10 but has a higher electrical resistance than the conductive material 17 , The sensor element 10 has a height which is about one-tenth to one-eighth the length of the pressure tube 8th equivalent. Preferably, the height of the sensor element is 10 between 3 and 5 mm.

The combustion chamber pressure transducer 22 according to the second embodiment can also be used as a glow plug. When applying a voltage between the terminal bolt 1 and the housing, not shown here 6 of the combustion chamber pressure transducer 22 According to the second embodiment, a current flows from the terminal bolt 1 through the center electrode 9 , through the conductive material 17 , through the sensor element 10 , to the floor 15 of the pressure tube 8th , and from there over the outer wall of the pressure tube 8th to the housing 6 , In the first place experiences the sensor element 10 , which has the largest electrical resistance R, a heating. The sensor element 10 gives this warming to the pressure tube 8th which makes the Combustion chamber of the internal combustion engine heated. The insulating layer 12 inside the pressure tube 8th prevents uncontrolled flow of current from the conductive material 17 to the outer wall of the pressure tube 8th ,

A longitudinal section through a combustion chamber pressure transducer 23 according to a third embodiment is in 4 shown. Also the combustion chamber pressure transducer 23 according to the third embodiment is similar to the combustion chamber pressure transducer 21 according to the first embodiment, which is why the differences are discussed here in the first place.

The pressure tube 8th again includes a sensor element 10 , which is designed as a conductive powder, wherein the center electrode 9 into the sensor element 10 protrudes and an electrical connection between the connecting bolt 1 and the sensor element 10 represents. The sensor element 10 takes, similar to the combustion chamber pressure transducer 22 according to the second embodiment, about one tenth to one eighth of the total height of the pressure tube 8th one. The remaining space inside the pressure tube 8th is with an insulating material 7 filled, which is also designed as a powder.

The center electrode 9 dives into the pressure pipe 8th and in the sensor element 10 one that the distance between the front side 13 the center electrode 9 and the floor 15 of the pressure tube 8th is relatively small, preferably about as large as the radius of the pressure tube 8th or smaller. On the inner lateral surface of the pressure tube 8th is an insulating layer 12 applied. The present is the insulating layer 12 on the entire inner surface of the pressure tube 8th provided, but it is also conceivable that only one to the ground 15 adjacent part of the inner circumferential surface of the pressure tube 8th , in particular the area in which the sensor element 10 is provided with the insulating layer 12 is provided.

Also the combustion chamber pressure transducer 23 according to the third embodiment acts as a glow plug. When applying a voltage between the terminal bolt 1 and the housing, not shown 6 a current flows from the terminal bolt 1 over the center electrode 9 through the sensor element 10 to the ground 15 of the pressure tube 8th and further over the outer wall of the pressure tube 8th to the housing, not shown 6 , Here, above all, the sensor element 10 , which has the greatest electrical resistance, heated and thereby gives the heat to the pressure tube 8th which then heats the combustion chamber of the internal combustion engine.

A combustion chamber pressure transducer 24 according to a fourth embodiment is in 5 shown in a longitudinal section. Also the combustion chamber pressure transducer 24 According to the fourth embodiment is constructed in many parts the same as the Brennraumdruckaufnehmer 21 according to the first embodiment, and therefore, at this point, the differences are primarily addressed.

Inside the pressure tube 8th is a designed as a powder sensor element 10 provided, which in the area of the soil 15 of the pressure tube 8th is arranged. The center electrode 9 dives into the sensor element 10 one. The front side 13 the center electrode 9 located inside the sensor element 10 , The distance of the front side 13 to the ground 15 of the pressure tube 8th is relatively small, in particular smaller than the radius of the pressure tube 8th ,

The to the sensor element 10 subsequent space inside the pressure tube 8th is with an insulating material 7 filled, which is also formed as a powder. An insulating layer 12 , which in other embodiments of the combustion chamber pressure transducer 22 . 23 is provided is at the combustion chamber pressure transducer 24 not provided according to the fourth embodiment.

Also the combustion chamber pressure transducer 24 according to the fourth embodiment acts as a glow plug. When applying a voltage between the terminal bolt 1 and the housing, not shown 6 of the combustion chamber pressure transducer 24 According to the fourth embodiment, a current flows through the terminal bolt 1 , through the center electrode 9 , through the sensor element 10 to the ground 15 of the pressure tube 8th and further over the outer wall of the pressure tube 8th to the housing, not shown 6 , In this case, in particular, the sensor element 10 , which has the highest electrical resistance, heated. The sensor element 10 gives the heat over the pressure tube 8th to the combustion chamber of the internal combustion engine.

A longitudinal section through a combustion chamber pressure transducer 25 according to a fifth embodiment is in 6 shown. Also the combustion chamber pressure transducer 25 according to the fifth embodiment is similar to the combustion chamber pressure transducer 21 according to the first embodiment, which is why the differences are discussed here in the first place.

The pressure tube 8th includes a sensor element 10 , which is designed as a conductive powder, wherein the center electrode 9 into the sensor element 10 protrudes and an electrical connection between the connecting bolt 1 and the sensor element 10 represents. The sensor element 10 takes, similar to the combustion chamber pressure transducer 22 according to the second embodiment, about one tenth to one eighth of the total height of the pressure tube 8th one. The remaining space inside the pressure tube 8th is with an insulating material 7 filled, which is also designed as a powder.

The center electrode 9 dives into the pressure pipe 8th and in the sensor element 10 one that the distance between the front side 13 the center electrode 9 and the floor 15 of the pressure tube 8th is relatively small, preferably about as large as the inner radius of the pressure tube 8th or smaller.

On the outer surface of the center electrode 9 is an insulation layer 19 applied. The insulation layer 19 extends approximately over the entire lateral surface of the center electrode 9 up to the front side 13 or until just before the face 13 , for example, up to 1 mm in front of the front side 13 ,

Also the combustion chamber pressure transducer 25 according to the fifth embodiment acts as a glow plug. When applying a voltage between the terminal bolt 1 and the housing, not shown 6 a current flows from the terminal bolt 1 over the center electrode 9 through the sensor element 10 to the ground 15 of the pressure tube 8th and further over the outer wall of the pressure tube 8th to the housing, not shown 6 , Here, above all, the sensor element 10 , which has the greatest electrical resistance, heated and thereby gives the heat to the pressure tube 8th which then heats the combustion chamber of the internal combustion engine.

A longitudinal section through a combustion chamber pressure transducer 26 according to a sixth embodiment is in 7 shown. Also the combustion chamber pressure transducer 26 according to the sixth embodiment is similar to the combustion chamber pressure transducer 21 according to the first embodiment, which is why the differences are discussed here in the first place.

The pressure tube 8th includes a sensor element 10 , which is designed as a conductive powder, wherein the center electrode 9 into the sensor element 10 protrudes and an electrical connection between the connecting bolt 1 and the sensor element 10 represents. The sensor element 10 fills the remaining space inside the pressure tube 8th at least approximately complete.

The center electrode 9 dives into the pressure pipe 8th and in the sensor element 10 one that the distance between the front side 13 the center electrode 9 and the floor 15 of the pressure tube 8th is relatively small, preferably about as large as the inner radius of the pressure tube 8th or smaller.

On the outer surface of the center electrode 9 is an insulation layer 19 applied. The insulation layer 19 extends approximately over the entire lateral surface of the center electrode 9 up to the front side 13 or until just before the face 13 , for example, up to 1 mm in front of the front side 13 ,

Also the combustion chamber pressure transducer 26 according to the sixth embodiment acts as a glow plug. When applying a voltage between the terminal bolt 1 and the housing, not shown 6 a current flows from the terminal bolt 1 over the center electrode 9 through the sensor element 10 to the ground 15 of the pressure tube 8th and further over the outer wall of the pressure tube 8th to the housing, not shown 6 , Here, above all, the sensor element 10 , which has the greatest electrical resistance, heated and thereby gives the heat to the pressure tube 8th which then heats the combustion chamber of the internal combustion engine.

The casing of the outer surface of the center electrode 9 with the insulation layer 19 as with the combustion chamber pressure transducer 25 according to the fifth embodiment and the combustion chamber pressure transducer 26 According to the sixth embodiment, is easier to carry out than the application of an insulating layer 12 on the inner surface of the pressure tube 8th as with the combustion chamber pressure transducer 22 according to the second embodiment and the combustion chamber pressure transducer 23 according to the third embodiment.

The invention is not limited to the described embodiments and the aspects highlighted therein. Rather, within the scope given by the claims a variety of modifications are possible, which are within the scope of professional practice.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102010038798 A1 [0004]
• EP 1517086 B1 [0005]
• EP 1500879 B1 [0006]

Claims (11)

Combustion chamber pressure transducer ( 21 . 22 . 23 . 24 . 25 . 26 ), for measuring a combustion chamber pressure in a combustion chamber of an internal combustion engine, comprising a sensor element ( 10 ), which points to the sensor element ( 10 ) acting pressure (p) converts to an electrically measurable size, characterized in that the sensor element ( 10 ) is designed as an electrically conductive powder, which in a change of the sensor element ( 10 ) (p) experiences a change in its electrical resistance (R), and that the sensor element ( 10 ) within a pressure tube ( 8th ) is arranged that a change of the pressure pipe ( 8th ) acting on a combustion chamber pressure a change of the on the sensor element ( 10 ) acting pressure (p) causes. Combustion chamber pressure transducer ( 21 . 22 . 23 . 24 . 25 . 26 ) According to claim 1, characterized in that the pressure tube ( 8th ) electrically and mechanically with a housing ( 6 ), which has an external thread. Combustion chamber pressure transducer ( 21 . 22 . 23 . 24 . 25 . 26 ) According to one of the preceding claims, characterized in that the pressure tube ( 8th ) formed at least approximately hollow cylindrical and at one end face with a bottom ( 15 ) is closed. Combustion chamber pressure transducer ( 21 . 22 . 23 . 24 . 25 . 26 ) according to claim 3, characterized in that a middle electrode ( 9 ) from the ground ( 15 ) facing away from the pressure tube ( 8th ) protrudes into it. Combustion chamber pressure transducer ( 21 . 22 . 23 . 24 . 25 . 26 ) according to claim 4, characterized in that the middle electrode ( 9 ) up to the sensor element ( 10 ). Combustion chamber pressure transducer ( 21 . 22 . 23 . 24 . 25 . 26 ) according to one of claims 4 to 5, characterized in that on an outer circumferential surface of the center electrode ( 9 ) is an insulation layer ( 19 ) is applied. Combustion chamber pressure transducer ( 21 . 22 . 23 . 24 . 25 . 26 ) according to one of claims 3 to 6, characterized in that on an inner circumferential surface of the pressure tube ( 8th ) at least partially an insulating layer ( 12 ) is provided. Combustion chamber pressure transducer ( 21 . 22 . 23 . 24 . 25 . 26 ) according to one of claims 3 to 7, characterized in that the sensor element ( 10 ) on the ground ( 15 ) is present. Combustion chamber pressure transducer ( 21 . 22 . 23 . 24 . 25 . 26 ) according to one of the preceding claims, characterized in that inside the pressure tube ( 8th ) an insulating material ( 7 ) is provided, which is designed as an electrically insulating powder. Internal combustion engine, comprising at least one combustion chamber pressure transducer ( 21 . 22 . 23 . 24 . 25 . 26 ) according to any one of the preceding claims. Method for measuring a combustion chamber pressure in a combustion chamber of an internal combustion engine, wherein an electrical resistance (R) of a sensor element ( 10 ), wherein the sensor element ( 10 ) is designed as an electrically conductive powder, which in a change of the sensor element ( 10 ) (p) experiences a change in its electrical resistance (R), and wherein the sensor element ( 10 ) within a pressure tube protruding into the combustion chamber ( 8th ) is arranged that a change of the pressure pipe ( 8th ) acting on a combustion chamber pressure a change of the on the sensor element ( 10 ) acting pressure (p) causes.

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