Patent Publication Number: US-11035319-B2

Title: Sealing assembly comprising a cylinder head, a cylinder head gasket and a crankcase

Description:
TECHNICAL FIELD 
     The present disclosure relates to an internal combustion engine for a motor vehicle, to a cylinder head gasket for an internal combustion engine, to a cylinder head for an internal combustion engine and to a crankcase for an internal combustion engine. The present disclosure furthermore relates to a motor vehicle, in particular a commercial vehicle, and to a method for discharging leakage gas coming from a combustion chamber of an internal combustion engine. 
     BACKGROUND 
     In internal combustion engines subject to high loads, sealing between the cylinder head and the crankcase is performed by a cylinder head gasket. The cylinder head gasket is often designed in such a way that it extends over all the cylinders. The crankcase and the cylinder head are clamped together by means of a plurality of high-strength screws distributed over the cylinder in order to reliably exert the required pressure on the gasket at the combustion pressures which arise (e.g. up to 300 bar and above). The external dimensions of a cylinder head gasket are dimensioned in such a way that no gap is formed between the cylinder head and the crankcase. Owing to the high screw forces, the cylinder head, the cylinder head gasket and the crankcase are pressed together firmly not only in the region of the combustion chambers but also in the outer regions of the sealing assembly. Owing to the high compression forces, there is good metallic sealing here too. In cases in which the engine has replaceable cylinder liners, the gasket is pressed against the cylinder liner installed in the crankcase. In the ideal case, the sealing assembly remains unobtrusive over the entire service life of the engine, and neither combustion gases nor other media which are exchanged between the cylinder head and the crankcase escape to a technically significant extent. 
     The prior art includes cylinder head gaskets which have grooves for various reasons. Cylinder head gaskets of this kind are disclosed in DE 43 37 758 C1, DE 10 2004 054 815 A1 and DE 195 34 962 A1, for example. 
     Cylinder head gaskets in internal combustion engines are typically flat gaskets, which can leak to a small extent, i.e. do not provide 100-percent sealing. Owing to the high ignition pressures in the combustion chamber, a certain small proportion of the combustion gases can escape during the ignition of the fuel/air mixture under certain preconditions. This can be tolerated up to a certain limit. A gasket of this kind is nevertheless referred to as “technically leaktight.” 
     In the course of the life of an engine, the sealing assembly can settle and/or wear, resulting in an increase in leakage of combustion gases (“creeping gas”). Other faults and relaxation can likewise lead to an increase in leakage. 
     If leakage gas escapes during ignition, this enters between the sealing surfaces into the interspaces between the crankcase and the cylinder head gasket or the cylinder head gasket and the cylinder head. The good metallic sealing in the inner and outer regions of the sealing assembly can prevent the leakage gas from getting back into the combustion chamber or penetrating further outwards. Consequently, the leakage gas may accumulate within the sealing assembly in regions and cavities (e.g. recessed core hole caps, holes etc.) around the combustion chambers. In the course of time, an excess pressure can arise, and this can damage the sealing assembly or other engine components. In this context, typical patterns of damage can lead to damage to cap screws, snapping off of screw heads and core hole caps being pressed in, as a result of which coolant enters the interspaces and spreads out in the sealing region and there can be permanent deformations of the cylinder head gasket by the incompressible cooling medium. Moreover, elastomers in the outer sealing region and beyond can be damaged, an excess pressure can arise in the coolant, the entire sealing surface can be damaged and the head assembly can hammer on the cylinder liner and damage the crankcase, for example. 
     SUMMARY 
     Starting from the problems described above, which can occur in connection with the escape of leakage gas from the combustion chamber, it is an object of the present disclosure to improve the sealing assembly comprising a cylinder head, a cylinder head gasket and a crankcase. 
     The internal combustion engine for a motor vehicle, in particular a commercial vehicle, has a cylinder head, in particular a single-cylinder cylinder head or a multi-cylinder cylinder head. The internal combustion engine furthermore has a crankcase, a cylinder head gasket, in particular a single-cylinder cylinder head gasket or a multi-cylinder cylinder head gasket. The cylinder head gasket is arranged between the cylinder head and the crankcase. The cylinder head, the cylinder head gasket and the crankcase form a sealing region for sealing at least one combustion chamber of the internal combustion engine. The internal combustion engine furthermore has a first recess. The first recess is arranged within the sealing region and at a distance from the at least one combustion chamber. The first recess is, in particular, a screw hole or a casting core hole, which is preferably closed by means of a core hole closure cap. The internal combustion engine furthermore additionally has a first leakage gas passage. The first leakage gas passage extends from the first recess to a first surface exposed to the environment of the internal combustion engine. As an alternative or in addition, the first leakage gas passage extends from the first recess to a ventilation passage of the internal combustion engine. The first leakage gas passage can be designed, in particular, as a depression. 
     The provision according to the present disclosure of the first leakage gas passage makes it possible for leakage gas that has accumulated in the first recess to be discharged from the first recess. Consequently, an excess pressure due to the accumulating leakage gas, which can damage the sealing assembly, is prevented from forming in the first recess. The sealing surfaces of the cylinder head, of the crankcase and of the cylinder head gasket form the sealing region. In particular, the leakage gas can be passed into an environment of the internal combustion engine. For this purpose, the leakage gas passage can open into a surface exposed to the environment of the internal combustion engine. The exposed surface can be an outer peripheral surface or an exposed end face, for example. Via the leakage gas passage, the leakage gas can also be discharged into an environment of the internal combustion engine via the intermediate stage of a ventilation system of the internal combustion engine. For this purpose, the leakage gas passage can open into a ventilation passage of the internal combustion engine. In particular, the leakage gas is diverted from screw holes and in the region of closed casting core holes since these regions have proven to be particularly critical regions. 
     According to one embodiment, the internal combustion engine can furthermore have a second recess. The second recess is arranged within the sealing region and at a distance from the at least one combustion chamber. The second recess is, in particular, a screw hole or a casting core hole, which is preferably closed by means of a core hole closure cap. In addition, the internal combustion engine can have a second leakage gas passage. The second leakage gas passage extends from the second recess to the first surface exposed to the environment of the internal combustion engine, to a second surface exposed to the environment of the internal combustion engine, to the first recess, to the first leakage gas passage and/or to the ventilation passage. In particular, the second leakage gas passage is designed as a depression. The provision of a second leakage gas passage makes it possible to divert leakage gas from another recess. Depending on the installation space situation, the leakage gas can be discharged directly into the environment through the second leakage gas passage, for example, e.g. via the first or second exposed surface. Alternatively or in addition, the leakage gas can be discharged into the environment through the second leakage gas passage via the intermediate stage of the first recess, the first leakage gas passage or the ventilation passage. 
     It is advantageous if the first recess and/or the second recess is/are provided in a sealing surface of the cylinder head, in a sealing surface of the crankcase and/or in a sealing surface of the cylinder head gasket. As an alternative or in addition, the first leakage gas passage and/or the second leakage gas passage is/are provided in a sealing surface of the cylinder head, in a sealing surface of the crankcase and/or in a sealing surface of the cylinder head gasket. For example, a first and a second recess as well as a first and a second leakage gas passage can all be provided in the same component (cylinder head, cylinder head gasket, crankcase). However, it is also possible for a leakage gas passage to extend through a plurality of components, e.g. the cylinder head gasket and the crankcase. It is furthermore possible for the recess and the associated leakage gas passage to be provided in different components. Thus, for example, a leakage gas can be diverted from a recess which extends only in the cylinder head or the crankcase, through a leakage gas passage which extends in the cylinder head gasket and is open to the recess. One example of a recess of this kind is a casting core hole closed by means of a core hole closure cap for closing a water core of the cylinder head or of the crankcase. 
     In particular, the first leakage gas passage and/or the second leakage gas passage can be designed as a groove, a channel or a slot. This allows a multiplicity of possible manufacturing techniques for the leakage gas passages, which can be manufactured according to requirements and possibilities. 
     In one illustrative embodiment, the first and/or the second surface exposed to the environment of the internal combustion engine is/are an outer peripheral surface of the cylinder head, an outer peripheral surface of the crankcase and/or an outer peripheral surface of the cylinder head gasket. Thus, ventilation of the leakage gas passage or of the leakage gas passages can be made possible in a simple manner. As an alternative or in addition, the ventilation passage can form a section of a cylinder head ventilation system and/or a section of a crank chamber ventilation system. 
     In one illustrative embodiment the at least one combustion chamber has two adjacent combustion chambers. The first recess and/or the second recess is/are arranged between the adjacent combustion chambers. It has been found that, in particular, the region between the combustion chambers and, in this case, especially the screw holes between the combustion chambers, is/are a critical region. By diverting the leakage gas out of this critical region, it is possible to prevent damage here. 
     According to another variant embodiment, the first leakage gas passage and/or the second leakage gas passage is/are formed by a forming method, in particular a compressive forming method, preferably by stamping. As an alternative or in addition, the first leakage gas passage and/or the second leakage gas passage is/are formed by a machining method, in particular a milling method. 
     The present disclosure also relates to a cylinder head gasket of an internal combustion engine. In particular, the cylinder head gasket is a single-cylinder cylinder head gasket or multi-cylinder cylinder head gasket. The cylinder head gasket has at least one combustion chamber opening, an outer peripheral surface and a first sealing surface for sealing with respect to a crankcase or a cylinder head. The cylinder head gasket furthermore has a first recess, which is arranged within the first sealing surface at a distance from the at least one combustion chamber opening. In particular, the first recess is a through hole, preferably a screw hole. The cylinder head gasket furthermore has a first leakage gas passage. The first leakage gas passage extends from the first recess to the outer peripheral surface and/or to a ventilation opening of the cylinder head gasket. In particular, the first leakage gas passage is designed as a depression which extends in the first sealing surface. 
     The provision according to the present disclosure of the first leakage gas passage makes it possible for leakage gas that has accumulated in the first recess to be discharged from the first recess. Consequently, an excess pressure due to accumulating leakage gas, which can damage the sealing assembly, is prevented from forming in the first recess. The leakage gas is passed out of the first recess into an environment of the internal combustion engine. For this purpose, the leakage gas passage opens into an outer peripheral surface of the cylinder head gasket, for example. 
     The cylinder head gasket furthermore preferably has a second recess, which is arranged within the first sealing surface and/or a second sealing surface at a distance from the combustion chamber opening. The second sealing surface is opposite the first sealing surface. The second recess is, in particular, a through hole, preferably a screw hole. The cylinder head gasket furthermore has a second leakage gas passage, which extends from the second recess to the outer peripheral surface, to the first recess, to a ventilation opening of the cylinder head gasket and/or to the first leakage gas passage. The second leakage gas passage is designed, in particular, as a depression which extends in the first sealing surface or the second sealing surface. 
     In one embodiment, the at least one combustion chamber opening has two adjacent combustion chamber openings. The first recess and/or the second recess is/are arranged between the two adjacent combustion chamber openings. As already explained above, it has been found that the region between the combustion chambers and thus the combustion chamber openings, in particular, and, in this case, in particular, the screw holes, is/are a critical region. By diverting the leakage gas out of this critical region, it is possible to prevent damage here. 
     In one illustrative embodiment, the cylinder head gasket is a single-ply cylinder head gasket, e.g. made from a metal. As an alternative, the cylinder head gasket can be a multi-ply cylinder head gasket, which is formed, for example, from a plurality of plies, e.g. metal plies, laid one on top of the other. The first leakage gas passage and/or the second leakage gas passage can preferably extend in an outer ply of the multi-ply cylinder head gasket. This allows simple manufacture of the leakage gas passages. 
     The present disclosure furthermore relates to a cylinder head, in particular a single-cylinder cylinder head or a multi-cylinder cylinder head for an internal combustion engine. The cylinder head has at least one combustion chamber surface for delimiting at least one combustion chamber, an outer peripheral surface and a sealing surface for sealing with respect to a cylinder head gasket. The cylinder head furthermore has a first recess, which is arranged within the sealing surface at a distance from the at least one combustion chamber surface. In particular, the first recess is a screw hole or a casting core hole, which is preferably closed by means of a core hole closure cap. The cylinder head furthermore has a first leakage gas passage, which extends from the first recess to the outer peripheral surface and/or to a ventilation passage of the cylinder head. In particular, the first leakage gas passage is designed as a depression which extends in the sealing surface. 
     Once again, the provision according to the present disclosure of the first leakage gas passage allows leakage gas that has accumulated in the first recess to be diverted out of the first recess. 
     It is advantageous if the at least one combustion chamber surface has two adjacent combustion chamber surfaces for two adjacent combustion chambers. The first recess and/or a second recess is/are arranged between the two adjacent combustion chamber surfaces. The second recess is arranged within the sealing surface at a distance from the at least one combustion chamber surface and is, in particular, a screw hole or a casting core hole, which is preferably closed by means of a core hole closure cap. The cylinder head has a second leakage gas passage, which extends from the second recess to the outer peripheral surface, to the first recess, to the first leakage gas passage and/or to the ventilation passage. In particular, the second leakage gas passage is designed as a depression which extends in the sealing surface. 
     The present disclosure furthermore relates to a crankcase for an internal combustion engine. The crankcase has at least one combustion chamber, an outer peripheral surface and a sealing surface for sealing with respect to a cylinder head gasket. The crankcase furthermore has a first recess, which is arranged within the sealing surface at a distance from the at least one combustion chamber. In particular, the first recess is a screw hole or a casting core hole, which is preferably closed by means of a core hole closure cap. In addition, the crankcase has a first leakage gas passage, which extends from the first recess to the outer peripheral surface and/or to a ventilation passage of the crankcase. In particular, the first leakage gas passage is designed as a depression which extends in the sealing surface. 
     As with the above-described internal combustion engine, the above-described cylinder head gasket and the above-described cylinder head, the provision according to the present disclosure of the first leakage gas passage allows leakage gas that has accumulated in the first recess to be discharged from the first recess. 
     Attention is drawn to the fact that the internal combustion engine, the cylinder head gasket, the cylinder head and/or the crankcase as disclosed herein and, in particular, in accordance with one of the above embodiments can have a plurality of first recesses, a plurality of first leakage gas passages, a plurality of second recesses and/or a plurality of second leakage gas passages. 
     In addition, the present disclosure relates to a motor vehicle, in particular a commercial vehicle, having an internal combustion engine, a cylinder head gasket, a cylinder head or a crankcase as disclosed herein. 
     The present disclosure furthermore relates to a method for discharging leakage gas, in particular creeping gas coming from a combustion chamber of an internal combustion engine, from a sealing region between a cylinder head, a cylinder head gasket and a crankcase of the internal combustion engine for sealing the combustion chamber. The method comprises the step of collecting the leakage gas in at least one recess formed within the sealing region. In particular, the recess is a screw hole or a closed casting core hole. The recess is at a distance from the combustion chamber of the internal combustion engine. The method furthermore comprises the step of guided discharge of the leakage gas out of the at least one recess outside the sealing region into an environment of the internal combustion engine and/or into a ventilation system of the internal combustion engine. In particular, the ventilation system is a crankcase ventilation system and/or a cylinder head ventilation system. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The above-described preferred embodiments and features of the present disclosure can be combined in any desired manner. Further details and advantages of the present disclosure are described below with reference to the attached drawings, in which: 
         FIG. 1  shows a section through a region of an internal combustion engine; 
         FIG. 2  shows a schematic view of a sealing assembly between a cylinder head, a cylinder head gasket and a crankcase; 
         FIG. 3A  shows a plan view of a region of a multi-cylinder cylinder head gasket; 
         FIG. 3B  shows a (longitudinal) cross section through the multi-cylinder cylinder head gasket; 
         FIG. 3C  shows an enlarged detail A of the cross section through the cylinder head gasket from  FIG. 3B ; 
         FIG. 4  shows a plan view of a region of a lower side of a multi-cylinder cylinder head; 
         FIG. 5  shows a perspective view of a region of a lower side and of an outer periphery of a multi-cylinder cylinder head; 
         FIG. 6  shows a plan view of a region of an upper side of a crankcase; and 
         FIG. 7  shows a perspective view of a region of an upper side and of an outer periphery of a crankcase. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a section through a region of an internal combustion engine  10 . The internal combustion engine  10  has a cylinder head  12 , a crankcase  14  and a cylinder head gasket  16 . The cylinder head gasket  16  is arranged between the cylinder head  12  and the crankcase  16 . The cylinder head  12  is attached to the crankcase  14  by means of a plurality of screws  13 , wherein the cylinder head gasket  16  is trapped. As a result, the cylinder head  12 , the crankcase  14  and the cylinder head gasket  16  form a sealing region  18  for sealing the combustion chamber  20 . The internal combustion engine  10  can have a plurality of combustion chambers  20 . In some embodiments, the internal combustion engine  10  can furthermore have a cylinder liner  22 , which is inserted in a cylinder bore of the crankcase  14 , as illustrated in  FIG. 1 . 
       FIG. 2  shows how leakage gases from the combustion chamber  20  can get into interspaces in the sealing region  18 . Attention is drawn to the fact that  FIG. 2  is purely schematic and that distances between the cylinder head  12  and the cylinder head gasket  16  and between the cylinder head gasket  16  and the crankcase  18  are shown in order to describe the leakage more clearly. In fact, a sealing surface  44  of the cylinder head  12  rests on a first sealing surface  26  of the cylinder head gasket  16  in the installed state. Likewise, a second sealing surface  36  of the cylinder head gasket  16  which is opposite the first sealing surface  26  rests on a sealing surface  46  of the crankcase  18 . 
     Owing to the high combustion and ignition pressures, leakage gas can escape from the combustion chamber  20  between sealing surfaces  44  and  26  and between sealing surfaces  36  and  46  during the operation of the internal combustion engine  10 . This is indicated in  FIG. 2  by arrows A and B. As explained in detail below, this leakage gas, which is also referred to as creeping gas, can accumulate in recesses in the sealing region  18  (the sealing surfaces  26 ,  36 ,  44 ,  46 ). 
     An illustrative cylinder head gasket  16 , which allows guided discharge of the leakage gas, is described below with reference to  FIGS. 3A to 3C . 
     In particular, the leakage gas can accumulate in a first recess  28 A and a second recess  29 A of the cylinder head gasket  16 . The recesses  28 A,  29 A are provided as screw holes, through which the cap screws  13  (see  FIG. 1 ) can be guided to screw them into the crankcase  14  (see likewise  FIG. 1 ). The recesses  28 A,  29 A are arranged between and at a distance from two adjacent combustion chamber openings  24  of the cylinder head gasket  16 . 
     Extending around the combustion chamber openings  24  of the cylinder head gasket  16  is a first sealing surface  26  for sealing with respect to a cylinder head  12  or a crankcase  14  (see  FIGS. 1 and 2 ). The recesses  28 A,  29 A are arranged within the first sealing surface  26 , i.e. are surrounded by the first sealing surface  26 . A first leakage gas passage  30 A and a second leakage gas passage  38 A extend in the first sealing surface  26 . 
     The first leakage gas passage  30 A extends between the first recess  28 A and an outer peripheral surface  32 A. Leakage gas from the combustion chamber  20  (see  FIGS. 1 and 2 ) which accumulates in the first recess  28 A can be discharged into the environment of the cylinder head gasket (of the internal combustion engine) through the first leakage gas passage  30 A. The formation of an excess pressure in the first recess  28 A is thus prevented, thereby enabling possible damage to be prevented. 
     The second leakage gas passage  38 A extends between the first recess  28 A and the second recess  29 A. Leakage gas from the combustion chamber  20  (see  FIGS. 1 and 2 ) which accumulates in the second recess  29 A can be discharged through the second leakage gas passage  38 A, the first recess  28 A and the first leakage gas passage  30 A. 
     In other embodiments, it is alternatively or additionally possible, for example, for the second leakage gas passage  38 A to open into the first leakage gas passage  30 A or into a ventilation passage of the internal combustion engine  10 , which can extend as a ventilation opening (not shown) through the cylinder head gasket  16 . It should furthermore be taken into account that, especially in the case of multi-cylinder cylinder head gaskets, like the cylinder head gasket  16  illustrated in  FIG. 3A , a plurality of first leakage gas passages  30 A, a plurality of first recesses  28 A, a plurality of second leakage gas passages  38 A and/or a plurality of second recesses  29 A can be provided, thus making it possible, in particular, to discharge leakage gas from recesses which are arranged between two adjacent combustion chamber openings  24 . The plurality of first recesses  28 A and/or the plurality of second recesses  29 A is therefore preferably arranged between two adjacent combustion chamber openings  24 . 
     Attention is furthermore drawn to the fact that there is the possibility, for example, that the first leakage gas passage  30 A and/or the second leakage gas passage  38 A extend/extends to a recess which is provided only in the cylinder head  12  or crankcase  14  (see  FIGS. 1 and 2 ). The cylinder head gasket  16  is then designed in such a way that the corresponding leakage gas passage and the corresponding recess partially overlap in the assembled state. 
     The cylinder head gasket  16  has further screw holes  27 . In some embodiments, these screw holes  27  can also be ventilated by means of one or more leakage gas passages, which open into the outer peripheral surface  32 , for example. 
     The cylinder head gasket  16  from  FIG. 3A  furthermore has a through hole  34 , which is surrounded by an elastomer. The through hole  34  is at a distance from the combustion chamber opening  24 . In the installed state, the through hole  34  connects a cooling passage in the cylinder head  12  and a cooling passage in the crankcase  14 . No leakage gas passage opening into the through hole  34  is provided since this would result in leakage of the coolant. 
       FIG. 3C  shows a detail from  FIG. 3B , which shows a longitudinal cross-sectional view of the cylinder head gasket  16 . As can be seen from  FIG. 3C , the first leakage gas passage  30 A is designed as an elongate depression in the first sealing surface  26 . Opposite the first sealing surface  26 , the cylinder head gasket  16  has the second sealing surface  36 . As an alternative or in addition, a leakage gas passage  39  can also extend in the second sealing surface  36  between a recess and a ventilation passage of the internal combustion engine  10  (see  FIG. 1 ) and/or the outer peripheral surface  32 A etc. 
     In the embodiment shown, the cylinder head gasket  16  is designed as a single-ply cylinder head gasket. In other embodiments, the cylinder head gasket  16  can have multiple plies, wherein the leakage gas passage or passages is/are preferably designed as depressions in a sealing surface of one outer ply or both outer plies. 
     With reference to  FIGS. 4 and 5  as well as  FIGS. 6 and 7 , it is explained below that leakage gas passages can also be provided in the cylinder head (cf.  FIGS. 4 and 5 ) and/or in the crankcase (cf.  FIGS. 6 and 7 ) in addition to or as an alternative to the cylinder head gasket (cf.  FIGS. 3A-3C ). 
       FIGS. 4 and 5  show different regions of a multi-cylinder cylinder head  12 . The cylinder head  12  has the sealing surface  44  for sealing with respect to a cylinder head gasket. The sealing surface  44  surrounds a plurality of combustion chamber surfaces  40 , which each serve as an upper limit of the combustion chambers  20  of the internal combustion engine  10  (see  FIG. 1 ). Opening into the combustion chamber surfaces  40  are inlet passages and outlet passages, into which poppet valves can be inserted, for example. Fuel injectors, ignition devices etc. can likewise extend at least partially into the combustion chambers  20  from openings in the combustion chamber surfaces  40 . The sealing surface  44  is delimited at the outside by an outer peripheral surface  32 B. 
     The cylinder head  12  has a plurality of first leakage gas passages  30 B. The first leakage gas passages  30 B connect a plurality of first recesses  28 B, which are designed as screw holes, to the outer peripheral surface  32 B. Consequently, leakage gas which is in the screw holes  28 B can be discharged into the environment. In addition, the cylinder head  12  has a plurality of second leakage gas passages  38 B. The second leakage gas passages  38 B connect a plurality of second recesses  29 B, which are likewise designed as screw holes, to the plurality of first recesses  28 B. Consequently, leakage gas can be passed out of the second recesses  29 B into the first recesses  28 B and, from there, discharged into the environment via the first leakage gas passages  30 B. The recesses  28 B,  29 B are arranged between adjacent combustion chamber surfaces  40  since there are particularly critical regions for the accumulation of leakage gas here. The leakage gas passages  30 B,  38 B are designed as depressions in the sealing surface  44 . 
     In other embodiments, the cylinder head can also be designed as a single-cylinder cylinder head. The leakage gas passages can extend in the sealing surface  44 , starting from further recesses. For example, the leakage gas passages can extend from casting core holes  50 B. The casting core holes  50 B are closed by core closure caps  52 B, with the result that a lubricant guide or coolant guide situated behind the core closure cap  52 B is sealed off with respect to the outside. For discharge of the leakage gas to the environment, the leakage gas passage or passages can also extend to a ventilation passage  42 B, which can form a section of a cylinder head ventilation system. 
       FIGS. 6 and 7  show different regions of a crankcase  14  from above. In the embodiment shown, a first leakage gas passage  30 C extends between a first recess  28 C and an outer peripheral surface  32 C of the crankcase  14 . Here, the first recess  28 C is designed as a casting core hole, which is closed by a closure cap. Further leakage gas passages  38 C extend between recesses  29 C and recess  28 C. Recesses  29 C are here designed as screw holes for the reception of cap screws  13  (see  FIG. 1 ). The leakage gas passages  30 C,  38 C are designed as depressions in the sealing surface  46 . The sealing surface  46  surrounds the combustion chambers  20 . The recesses  28 C,  29 C are arranged between adjacent combustion chambers  20 . The crankcase  16  can furthermore have a ventilation passage of a crankcase ventilation system, which leads to a crank chamber ventilation system. In addition or as an alternative, existing leakage gas passages can open into the ventilation passage. 
     A person skilled in the art will recognize that the configuration and arrangement of the recesses and leakage gas passages in the above-described embodiments of the cylinder head gasket, of the cylinder head and of the crankcase can be analogous. In other words, all the features which are related to the recesses and leakage gas passages and are described herein with reference to the cylinder head gasket, the cylinder head or the crankcase can be provided in the same way on the respective other components. 
     As explained above, the leakage gas passages  30 A,  30 B,  30 C,  38 A,  38 B,  38 C make it possible to carry out a method for discharging leakage gas from at least one combustion chamber  20 . Here, the method comprises collecting the leakage gas in at least one recess  28 A,  28 B,  28 C,  29 A,  29 B,  29 C, in particular a screw hole or a casting core hole, formed within the sealing region  18 . By means of the leakage gas passages  30 A,  30 B,  30 C,  38 A,  38 B,  38 C, the accumulated leakage gas can then be discharged in a guided manner from the at least one recess  28 A,  28 B,  28 C,  29 A,  29 B,  29 C into an environment of the internal combustion engine  10  and/or into a ventilation system of the internal combustion engine  10 . 
     The present disclosure is not restricted to the preferred illustrative embodiments described above. On the contrary, a large number of variants and modifications is possible, which likewise make use of the inventive concept and therefore fall within the scope of protection. In particular, the present disclosure also claims protection for the subject matter and features of the dependent claims, independently of the claims to which they refer. 
     LIST OF REFERENCE SIGNS 
     
         
           10  internal combustion engine 
           12  cylinder head 
           13  cap screw 
           14  crankcase 
           16  cylinder head gasket 
           18  sealing region 
           20  combustion chamber 
           22  cylinder liner 
           24  combustion chamber opening 
           26  sealing surface (cylinder head gasket) 
           28 A recess (cylinder head gasket) 
           28 B recess (cylinder head) 
           28 C recess (crankcase) 
           29 A recess (cylinder head gasket) 
           29 B recess (cylinder head) 
           29 C recess (crankcase) 
           30 A leakage gas passage (cylinder head gasket) 
           30 B leakage gas passage (cylinder head) 
           30 C leakage gas passage (crankcase) 
           32 A outer peripheral surface (cylinder head gasket) 
           32 B outer peripheral surface (cylinder head) 
           32 C outer peripheral surface (crankcase) 
           34  through hole 
           36  sealing surface (cylinder head gasket) 
           38 A leakage gas passage (cylinder head gasket) 
           38 B leakage gas passage (cylinder head) 
           38 C leakage gas passage (crankcase) 
           39  leakage gas passage (cylinder head gasket) 
           40  combustion chamber surface 
           42 B ventilation passage 
           44  sealing surface (cylinder head gasket) 
           46  sealing surface (crankcase) 
           50 B casting core hole 
           52 B closure cap