WO1998036159A1

WO1998036159A1 - Gas shuttle valve, and method for measuring the pressure in the combustion chamber of an internal combustion chamber

Info

Publication number: WO1998036159A1
Application number: PCT/EP1998/000830
Authority: WO
Inventors: Heinz Leiber
Original assignee: Lsp Innovative Automotive Systems Gmbh
Priority date: 1997-02-14
Filing date: 1998-02-13
Publication date: 1998-08-20
Also published as: EP0963509B1; DE59800762D1; JP2002511120A; EP0963509A1; DE19705621A1

Abstract

The head (81) of a gas shuttle valve presents on its front face a valve seat (84) which is designed preferably, at least partly, as a membrane (90) and which, owing to the pressure prevailing inside the combustion chamber (83), undergoes a deformation. This deformation can be transferred through a valve stem (82) to a position sensor, with the result that the pressure inside the combustion chamber can be measured (13).

Description

Gas exchange valve and method for measuring the pressure in a combustion chamber of an internal combustion engine

The invention relates to a gas exchange valve with a valve disk, the end face of which, in the installed state of the gas exchange valve, faces a combustion chamber of an internal combustion engine

The invention also relates to a method for measuring the pressure in a combustion chamber of an internal combustion engine

As is known, the cylinders of internal combustion engines are provided with gas exchange valves. A cylinder of a four-stroke engine has at least one intake valve and at least one exhaust valve

Gas exchange valves essentially consist of a front, conical valve disc, as well as an elongated valve stem attached to the rear of the valve valve springs are usually arranged at the free end of the valve stem, as well as an actuating device that axially displaces the valve stem in time with the gas exchange, while the return movement of the valve by means of Valve spring is effected

The valve disc is in the closed position of the valve with its outer edge, the so-called valve seat, on a counter surface of the cylinder head, which forms the outlet or inlet for the respective cylinder typically at about 45 ° cone angle and ground for the purpose of a good sealing effect

Gas exchange valves are exposed to strong mechanical and thermal loads

The mechanical loads are due to the fact that switch valves are actuated up to 3,000 times per minute, that is to say they are raised and then hit the valve seats again

The thermal load on gas exchange valves is different.While inlet valves are less thermally loaded because they are constantly cooled by relatively cold incoming fresh gases, the hot burned combustion gases flow continuously around the outlet valves.With inlet valves, a working temperature of up to about 500 ° C is therefore expected, while Exhaust valves on the valve plate can be loaded with up to 800 ° C

In the case of the outlet valves, the valve disk must therefore be made from a high-temperature-resistant steel which is both corrosion and scale resistant, for example a chrome-manganese steel. However, such steels have poor sliding properties, so that special bushes or special sections of the valve stem are in the area of the valve stem Valve stem must be provided, which consist for example of a chromium-silicon steel and have such good sliding properties as well as sufficient thermal conductivity

In addition, numerous measures have become known in order to improve the heat dissipation on switch valves. For example, it is known to make the valve stem hollow and to fill it partially, for example to about 60%, with sodium. The sodium is at the operating temperature of the gas switch valves in liquid state of aggregation and is thrown around during the working cycle of the gas exchange valves in the cavity of the valve stem, so that an improved heat dissipation can be ensured Studies on the heat balance of gas exchange valves have shown that, for exhaust valves, around 70% of the heat coming from the combustion chamber is absorbed by the end of the valve plate facing the combustion chamber, while around 30% of the heat is transferred from the outflowing fuel gases to the back of the valve plate and the valve stem From the exhaust valves, this heat is in turn emitted 76% via the valve seats on the cylinder head and 24% via the valve stem on its guide bushings, and thus also the cylinder head

From EP-A-0 048 333 a gas exchange valve is known in which the conical rear side of the valve plate is provided with a discharge funnel which is to serve as a heat shield. The known gas exchange valve is also provided with an additional heat shield in one exemplary embodiment, which is located on the front of the combustion chamber facing end face of the valve plate is arranged between this heat shield on the opposite side and the front face of the valve plate there should be a cavity

Both the discharge funnel and the end-side heat shield are made of sheet metal about 0.5 mm thick, and the core of the valve plate and the valve stem are made of metal

A similar gas exchange valve with an end-side heat shield is known from DE-A-32 47 487. Here too, a cavity is provided between the plate-shaped heat shield located in front of the end of the valve plate and the valve plate, which if necessary is filled with a high-temperature-resistant material, for example asbestos In this known gas exchange valve too, the heat shield is made of metal

In addition to metallic gas exchange valves, purely ceramic gas exchange valves are also known, which, however, have considerable mechanical disadvantages due to the very brittle properties of ceramic From DE-A-33 02 650 a compound valve is known in which the valve stem is made of metal and the valve plate is made of a ceramic. Although the valve plate, which is subjected to high thermal loads, is more resistant to these thermal loads, it has the disadvantage that the Valve plate is at the same time the mechanically most stressed component of the gas exchange valve, but on the other hand ceramic is only slightly able to withstand the shock and impact loads that occur with gas exchange valves in the area of the valve plate

A similar ceramic-metal composite valve is also known from DE-A-39 26 431, where a steel tie rod is guided as an inner element through the valve stem and up to the front in the valve plate and on its face, while the outer area of the valve plate and the Valve stem is formed by a ceramic material. The disadvantages already described also occur with this known composite valve

Finally, DE-A-32 36 354 describes a further composite valve which, although consisting largely of metal, is provided on the end face of the valve plate with an oxide ceramic plate as a heat shield. In this known composite valve, it is known to install the ceramic heat shield in this way that thermally caused expansion of the heat shield can be compensated for by an appropriate type of installation and no damage to the heat shield can occur

Another disadvantage of the known gas exchange valves is that they have a comparatively large mass. However, since these masses have to be moved with each gas exchange process, a not insignificant portion of the engine power is required for driving the valves, which portion has to be branched off to the camshaft. to operate the valves The power required for this includes not only compressing the valve springs, but also accelerating and braking the gas exchange valves themselves.Therefore, if gas exchange valves have a high mass, it may well be that all of them drive a drive power of some kW is required which in turn is reflected in increased engine fuel consumption

Although the aspect of weight reduction for the simultaneous reduction of moving masses has already been taken into account in engine construction in several respects, as far as can be seen, however, the gas exchange valves have so far remained essentially unaffected

For the control of internal combustion engines, it is also known to record the pressure curve in the cylinder during a complete gas exchange process and to derive control signals therefrom, for example for a gasoline injection. However, the known methods for measuring the pressure in a combustion chamber have not grown beyond the stage of laboratory processes because Until now, it was necessary to install special pressure sensors in the engine block or the cylinder head in order to record the pressure in the combustion chamber. However, such additional elements have so far been too complex for series production of engines to further develop that the disadvantages mentioned are avoided

In particular, the invention should make it possible to provide a high-temperature-resistant and light gas exchange valve which is durable and which, due to its lower weight compared to conventional gas exchange valves, also enables savings in gasoline consumption. Furthermore, an improvement in the method for measuring the pressure is also intended In the combustion chamber of an internal combustion engine, an even better control of the combustion process will be possible. As is known, a better diagnosis of the combustion process is also possible

In the case of a gas exchange valve of the type mentioned at the outset, the object is achieved according to the invention in that the gas exchange valve has means for detecting the pressure in the closed state of the gas exchange valve. The means can be the valve plate or part of the valve plate Underlying the sensor, additional openings in the combustion chamber and additional components are not required

In a method of the type mentioned at the outset, the object is further achieved according to the invention in that an elastic deformation of a gas exchange valve connected to the combustion chamber is measured in its closed state

The object underlying the invention is completely achieved in this way

If the end face of the gas exchange valve is designed as an elastically deformable part, the gas exchange valve can be used to detect the pressure in the combustion chamber of the internal combustion engine so that the combustion process can be controlled with it. In contrast to conventional devices, no modification to the engine block or to the cylinder head is therefore necessary to become because the slightly modified gas exchange valves themselves provide the possibility to carry out a pressure measurement.The actual function of the gas exchange valves themselves does not change, unlike for example with spark plugs, in which attempts have also already been made to integrate pressure sensors into them measure during the compression phase and the combustion phase if you take the crankshaft angle into account during the measurement

The gas exchange valves according to the invention with an elastically deformable plate or plate part on the end face are preferably further developed in that the plate part is at least partially designed as a membrane

This measure has the advantage that there is a relatively large measurement effect. Mechanically stable membranes can therefore be used to achieve distances in the range from 0.01 to 0.1 mm at maximum operating pressure in the combustion chamber It is also particularly preferred if the plate part is connected to a valve stem and the valve stem is in turn connected to a displacement sensor

This measure has the advantage that the measuring path via the valve stem, that is to say an already existing component, is transferred to a location at a distance from the combustion chamber at which measuring arrangements which are not so thermally sensitive can be provided

For example, an end of the valve stem facing away from the plate part can be connected to the displacement sensor. In other applications, it may be more expedient for an end of the valve stem facing away from the divider part to be supported on a spring plate, the spring plate being connected to the displacement sensor Valve actuation means, i.e. even further from the measuring point, is possible

These measures have the advantage that, depending on the installation conditions, an optimal connection to the displacement sensor can be achieved

In embodiments of the invention, the plate part, on its side facing the combustion chamber in the installed state, is provided with a heat shield, as is known per se. The heat shield preferably consists of a high-temperature-resistant, in particular ceramic material. It is preferably designed as a plate

In variants of this exemplary embodiment, the plate is positively attached at the edge of the plate part, preferably by bordering, preferably the bordering is carried out at high temperatures (approx. 500 ° C.)

This measure has the advantage that the arrangement can be produced in large series in a simple manner. Bordering at, for example, 500 ° C. has the advantage that a slack due to the different expansion coefficients and thus expansion at the operating temperature is avoided In another variant, the plate can also be fastened to the center of the plate part

This measure has the advantage that the plate can deform more easily, especially under the influence of changing temperatures

The plate can preferably be fastened to the plate part by means of a bolt. The boizen is in particular welded to the plate part

In order to protect the bolt against the heat emanating from the combustion chamber, it can be provided in a further embodiment of the invention that the bolt is in turn covered on the end face by means of a further heat shield, which in turn is preferably designed as a ceramic plate and by means of a flange part welded to the bolt can be held in front of the bolt

In further exemplary embodiments of the invention, the heat shield is held at a distance from the plate part. It can be held firmly or with axial play. In the latter case, it is expedient if the first heat shield is resiliently supported relative to the plate part

These measures have the advantage that the heat shield, in particular in its embodiment as a ceramic plate, can expand or contract when the temperature changes without causing high mechanical stresses

One can provide a discharge funnel, e.g. made of metal, on the back of the valve plate, which is not connected to the shaft. This discharge funnel, which is arranged on the back of the valve plate, can also be designed as a ceramic component and in this way achieves a significantly higher thermal load capacity. This applies in particular in the case of an exhaust valve in which the hot burned combustion gases flow along the rear of the valve and represent a considerable thermal load there Compared to the metallic discharge funnels known in the prior art, there is the considerable advantage that, with a smaller thickness and therefore with a lower mass, at least as good if not better thermal insulation can be achieved, so that the mass of the valve is reduced

The ceramic discharge funnel can be designed in such a way that a cavity remains between the discharge funnel, the valve stem and the plate part. This measure has the advantage that considerable weight savings (moving mass) are possible at this point

In a further exemplary embodiment of the invention, the ceramic discharge funnel encloses a further inner discharge funnel, which is preferably enclosed at a distance by the ceramic discharge funnel. The inner discharge funnel preferably consists of metal, in particular aluminum

This measure has the advantage that the heat shield function is further improved by good heat dissipation in the valve stem, in that the back of the valve plate and the valve stem are protected by a double arrangement of discharge funnels. If the inner discharge funnel is made of aluminum, this does not make any noticeable Weight increase because the aluminum is primarily thermally protected by the outer ceramic discharge funnel, it also has a long-term effect. The interior of the discharge funnel and the valve stem can be filled with a heat-conducting powder, e.g. magnesium oxide

In the case of the pressure measurement method mentioned at the outset, the pressure will be measured in new valves and the displacement sensor will be calibrated. In this case, the pressures other new valves are preferably included, for example a new average is formed

Further advantages result from the description and the attached drawing It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the combination indicated in each case, but also in other combinations or in any configuration without departing from the scope of the present invention

Exemplary embodiments of the invention are shown in the drawing and are explained in more detail in the following description

1 shows a side view, partly in section, of a first exemplary embodiment of a gas exchange valve according to the invention, in the installed state,

Fig. 2 is an illustration on an enlarged scale, similar to Fig. 1, but one

Show variant in the area of the valve plate,

3 shows a detail from FIG. 2 on an even larger scale,

4 shows a variant of FIG. 3, and

Fig. 5 in partial representation, similar to Fig. 1 and 2, another

Exemplary embodiment of a gas exchange valve according to the invention

In FIG. 1, 10 designates a gas exchange valve as it is used, for example, in a four-cylinder gasoline engine. The gas exchange valve 10 is essentially located in a cylinder head 11, in which a gas duct 12 bent at the side is arranged of an exhaust valve as indicated by an arrow 13. In the case of an intake valve, the direction of flow of the fresh gases is reversed. The gas exchange valve 10 is aligned in the direction of its longitudinal axis 14 with a combustion chamber 15 of the internal combustion engine. The gas exchange valve comprises at its front end 10 a valve plate 16 and at its rear end a valve stem 17. The valve stem 17 is guided via a guide bushing 18 in the cylinder head 11.

A spring plate 21 is attached to an upper end 20 of the valve stem 17. The spring divider 21 supports a helical spring 22, which is supported at its other end on a surface 23 of the cylinder head 11. In this way, the gas exchange valve 10 is biased upwards in the illustration of FIG.

An actuation device indicated by 24, which is intended to symbolize the valve drive with camshaft, bucket tappets and the like, acts on the upper end 20 of the valve stem 17, as indicated by an arrow 25. For a gas exchange cycle, the gas exchange valve 10 is displaced downward along the axis 14 against the force of the spring 22 by means of the actuating device 24, as shown in dashed lines in FIG. 1 below. The valve lift (not to scale) is denoted by h. From this open position of the gas exchange valve 10, this returns under the restoring force of the spring 22 to its upper, closed position shown in FIG. In this closed position, a conical seat surface 28 rests on the rear circumference of the valve plate 16 on a correspondingly shaped counter surface 29 of the cylinder head 11. The gas channel 12 is in turn closed off from the combustion chamber 15.

The valve stem 17 essentially consists of a tube 35, the interior 36 of which can for example be partially filled with metallic sodium, which is liquid at the operating temperature of the gas exchange valve 10.

In order to protect the valve stem 17 against the hot fuel gases during the outlet phase of the gas exchange valve 10, a discharge funnel 40 is provided. The discharge funnel 40 consists of an aluminum sheet. Its upper end 42 encloses the tube 35 of the valve stem 17th

The front, widened end 43 of the discharge funnel 40 is connected to an edge 46 of a plate part 47 of the valve plate 16. This is indicated as flanging at 44. The plate part 47 is formed at least in the inner area as a membrane 48. At the center of the membrane 48, the tube 35 is butt-fitted and welded onto a corresponding receptacle of the membrane 48 at 49.

In front of the membrane 48 there is a heat shield 50 which is designed as a thin ceramic plate. The heat shield 50 thus covers the membrane 48 with respect to the combustion chamber 15. The heat shield 50 is flanged on its circumference 51 with the edge 46 of the plate part 47, as indicated at 52. The valve disk and also the discharge funnel can be provided with beads.

If, as indicated by an arrow 53, a pressure in the combustion chamber 15 is exerted on the heat shield 50 and thus the membrane 48, the tube 35 is shifted upwards in FIG. The free end 20 of the tube 35 or the valve stem 17 is connected to a button 54 of a displacement sensor 55, the connection of which is designated 56.

If, for example, the maximum pressure in the combustion chamber causes a deflection of heat shield 50 and membrane 48 in the order of magnitude of 0.01 mm, this deflection is transmitted directly to displacement sensor 55 and can be taken off as an electrical signal at connection 56. The actual function of the gas exchange valve 10 is not affected by these measures.

During the inlet phase, as mentioned, the cool fresh gases flow through the gas duct 12 against the direction of arrow 13, and flow around the discharge funnel 40. Since the discharge funnel consists of a relatively good heat-conducting material (aluminum), the pipe 35 and the valve plate 46 protected. In addition, the gases are guided aerodynamically by the shape of the discharge funnel 40, so that as little losses as possible are caused by eddy formation and the like.

Since the discharge funnel 40, as mentioned, is designed as a thin sheet metal part, a considerable cavity remains between it and the tube 35 of the valve stem 17 41. This makes it obvious that the gas exchange valve 10 shown in FIG. 1 is a lightweight component, the lower mass of which only requires a correspondingly low drive power with each gas exchange. The inside of the funnel 40 and / or the tube 35 can be filled with magnesium powder.

In the variant shown in FIG. 2, in which the same components are identified by the same reference symbols and similar components by adding an “a” to the reference symbol, the heat shield 50a is arranged on an underside 58 of the telephoto part 47a. As indicated at 51a ′, the heat shield 50a can also protrude laterally beyond the plate part 47a.

The heat shield 50a is attached to the plate part 47a by means of a central fastening bolt 60, the details of which are shown in FIGS. 3 and 4 using two variants.

3, the fastening bolt 60 has three sections 61, 62, 63, each with a smaller diameter, from the inside to the outside. With the first section 61, the fastening bolt 60 is arranged in the center of the membrane 48. The second section 62 of the fastening bolt 60 guides the heat shield 50a, for example a ceramic plate, without axially fixing it. As a result, an axial play 70 can arise between the heat shield 50a and the first section 61 of the fastening bracket 60, a spring 71 expediently ensuring elastic tension of the heat shield 50a with respect to the divider part 48.

The third section 63 of the fastening bolt 60 holds the heat shield 50a in the axial direction from the outside. For this purpose, a fastening disk 69 is welded to the circumference of the third section 63, as indicated by 68.

In the preferred embodiment of FIG. 4, the ceramic disk or the valve disk is slightly conical, so that the two parts only touch on the outside without pretensioning. Since here the fastening parts 62 and 63 allow a pretension to be exerted, the two the parts are printed against each other so that they lie against each other overall. Then the welding 68 is carried out. A flattening according to FIG. 1 can be omitted. The cylinder pressure is transmitted to the valve disk via the ceramic disk

In the exemplary embodiment shown in FIG. 5, a cylinder head 77 is again shown, in whose gas channel 78, which acts as an outlet channel, fuel gases flow out, as indicated by an arrow 79

The gas exchange valve, designated as a whole by 80, has a valve plate 81 and a valve stem 82. The valve plate 81 is directed against a combustion chamber 83. It has a plate part 84, on the edge of which is designated 85. A heat shield 86, again preferably a ceramic plate, is located on the edge 85 The heat shield 86 is fastened to the plate part 84 by means of a central fastening bolt 87, preferably using one of the techniques described in FIGS. 3 and 4. However, the flanging according to FIG. 1 can also be used

To compensate for an axial play of the heat shield 86, for example, a plate spring can be arranged between the heat shield 86 and the plate part 84

The valve stem 82 consists of a tube 92, the tube 92 being able to enclose an inner tube 93 and this in turn can enclose an interior 94. The tube 93 can be an aluminum tube, for example. The interior 94 can be filled with metallic sodium or magnesium in the manner already described

The tube 92 is preferably tapered at its lower end and welded at 91 into a counter-conical receptacle of the membrane 90

A first discharge funnel 95, which is preferably made of aluminum sheet, encloses the tube 92 with its upper, tapered end. The end of the first discharge funnel 95 is attached to the plate part 84. It serves for better cooling and heat dissipation of the valve plate 81.

There is also a second, outer discharge funnel 96, which consists of a ceramic material. The upper, tapered end of the second discharge funnel 96 encloses the valve stem 82, that is to say the tube 92 in the exemplary embodiment shown. The lower, expanded end of the second discharge funnel 96 is connected to the edge 85 of the plate part 84, for example by bordering, as at 97 indicated.

Since the second discharge funnel 96 has only a certain wall thickness, an interior 98 remains between it and the tube 92 or the plate part 84 and specifically its inner membrane 90.

This also makes it clear that the gas exchange valve shown in FIG. 5 is a lightweight component which, moreover, has excellent thermal resistance in the rear region of the valve plate 81.

In the exemplary embodiment shown in FIG. 5, the outer discharge funnel 96 is shaped in such a way that the flow of the outflowing fuel gases is influenced as little as possible. Alternatively, each of the two discharge funnels 95 and 96 can be omitted.

Claims

claims

1 gas exchange valve for an internal combustion engine, characterized in that the gas exchange valve (10) has means (47, 84) for detecting the pressure in the combustion chamber (13, 83) in the closed state

2 gas exchange valve according to claim 1, characterized in that the mean of the plate (16, 84) of the valve or a part thereof

3 gas exchange valve according to claim 1 or 2, characterized in that the plate or the Tellerteii (47, 84) is designed to be elastically deformable, and that means are provided to detect the elastic deformation of the plate or telier part

4 gas exchange valve according to claim 2 or 3, characterized in that the plate or the plate part (47, 84) is at least partially designed as a membrane (48, 90)

5 gas exchange valve according to claim 3 or 4, characterized in that the plate or the Tellerteii (47, 84) is connected to a valve stem (17, 82) and that the valve stem (17, 82) in turn with a displacement sensor (55) in connection stands

6 gas exchange valve according to claim 5, characterized in that an end facing away from the plate or plate part (47, 84) of the valve stem (17, 82) is connected to the displacement sensor (55)

7 gas exchange valve according to claim 5, characterized in that an end facing away from the plate or plate part (47, 84) of the valve stem (17, 82) on a spring plate (21) is supported, and that the spring plate (21) with the displacement sensor (55 ) connected is

Gas exchange valve according to claim 5, characterized in that the displacement sensor is attached to the valve actuation means (eg electromagnetic actuating device)

Gas exchange valve according to one or more of Claims 3 to 8, characterized in that the plate or plate part (47, 84) is provided with a heat shield (50, 86) on its side facing the combustion chamber (15, 83) in the installed state

Gas exchange valve according to claim 9, characterized in that the heat shield (50, 86) consists of a high-temperature-resistant, preferably ceramic material

Gas exchange valve according to claim 9 or 10, characterized in that the heat shield (50, 86) is designed as a plate

Gas exchange valve according to claim 11, characterized in that the plate is attached to the edge (46) of the plate or telephoto part (47) in a form-fitting manner, preferably by bordering (52), the boarding preferably taking place at the operating temperature of the gas exchange valve

Gas exchange valve according to claim 12, characterized in that the plate is fastened in its center to the plate or divider part (47a, 84)

Gas exchange valve according to claim 13, characterized in that the plate is fastened to the plate or plate part (47a, 84) by means of a bolt (60, 87)

Gas exchange valve according to claim 14, characterized in that the bolt (60) is welded (66) to the plate or plate part (47a)

16. Gas exchange valve according to claim 14 or 15, characterized in that the bolt (60 ') is in turn covered on the end face by means of a further heat shield (75).

17. Gas exchange valve according to one or more of claims 5 to 16, characterized in that the heat shield (50a; 86) is held at a distance (70) in front of the plate or plate part (47; 84).

18. Gas exchange valve according to claim 17, characterized in that the heat shield (50a; 86) relative to the plate or plate part (47a; 84) is resiliently supported (71; 89).

19. Gaschweiventit according to any one of claims 1 to 18, characterized in that the rear of the valve plate (16.81) is provided with a discharge funnel (40; 96), the circumference of one, the end face of the valve plate (16;

81) forming plate part (47; 84), tapering to the valve stem (17;

82) leads and encloses this, whereby the fuel gases in the gas canal (12; 78) are guided aerodynamically and at the same time the end components of the gas exchange valve (10; 80) are thermally protected.

20. Gas exchange valve according to claim 18, characterized in that the discharge funnel is made of metal.

21. Gas exchange valve according to claim 19 or 20, characterized in that the space (41) between the funnel (40) valve stem (17) and valve plate (47) and / or the interior (14) of the valve stem (17) with a metal powder (for example Magnesium) is filled.

22. Gas exchange valve according to one of claims 1 to 21, characterized in that the discharge funnel (40; 86) and / or the valve plate (16; 81) is provided with beads.

23. Gas exchange valve according to claim 20, characterized in that the discharge funnel (96) is designed as a ceramic component.

24. Gas exchange valve according to claim 23, characterized in that the ceramic discharge funnel (96) with the valve stem (82) and with a rear side of the plate part (47; 84) form an interior (87).

25. Gas exchange valve according to claim 23 or 24, characterized in that the ceramic discharge funnel (96) encloses a further inner discharge funnel (95).

26. Gas exchange valve according to claim 25, characterized in that the ceramic discharge funnel (96) encloses the inner discharge funnel (95) at a distance.

27. A method for measuring the pressure in a combustion chamber (15; 83) of an internal combustion engine, characterized in that an elastic deformation of a gas exchange valve (10; 80) connected to the combustion chamber (15; 83) is measured in its closed state.

28. The method according to claim 27, characterized in that the elastic deformation of a plate part (47; 84) is measured, which forms an end face of a valve plate (16.81) of the gas exchange valve (10; 80).

29. The method according to claim 28, characterized in that the elastic deformation of a membrane (48; 90) of the plate part (47; 84) is measured.

30. The method according to claim 28 or 29, characterized in that an end face of the plate part (47; 84) is covered by means of a heat shield (50; 75; 86) against heat in the combustion chamber (15; 83).

31. The method according to one or more of claims 27 to 30, characterized in that the elastic deformation via a valve stem (17; 82) is transmitted to a displacement sensor (55).

32. The method according to any one of claims 27 to 31, characterized in that the pressure is measured in the course of the compression and the Verreπnuπgsphase controlled by the crank angle.

33. The method according to any one of claims 27 to 32, characterized in that the pressure is measured when the valve is new and the displacement sensor is calibrated.

34. The method according to claim 33, characterized in that the pressure measurements of other cylinders are included in the calibration process.