DE102016201705B4 - Internal combustion engine with cylinder block and cylinder head and method for limiting and reducing the mechanical load of a proposed seal - Google Patents

Abstract

An internal combustion engine having at least one cylinder head, which has at least one cylinder and is connected to a mounting side with a cylinder block to form clamping forces, in which - between the cylinder block and the at least one cylinder head a seal is provided and clamped, and - in the cylinder block and the at least one cylinder head bores are provided, wherein the at least one cylinder head and the cylinder block are interconnected by means of connecting elements (1) having at least one thread and inserted into the bores of the at least one cylinder head and the cylinder block and bolted to form clamping forces, characterized characterized in that at least one multi-part connecting element (1) is provided, in which a head part (1a) of the connecting element (1) via a filled with hydraulic fluid (3) pressure chamber (2) with a shaft (1b) of the connecting element (1) in force is coupled manner, wherein - the shaft (1b) at one end facing the head part (1a) has a control piston (1c) arranged in the pressure chamber (2) translationally displaceable and stored and frontally by a pressure of the hydraulic fluid (3) is pressurized, and - the clamping force between the cylinder block and the at least one cylinder head using the hydraulic fluid (3) is variable.

Description

The invention relates to an internal combustion engine having at least one cylinder head, which has at least one cylinder and is connected to a mounting side with a cylinder block to form clamping forces, in which
- Between the cylinder block and the at least one cylinder head, a seal is provided and clamped, and
- Are provided in the cylinder block and the at least one cylinder head bores, wherein the at least one cylinder head and the cylinder block are interconnected by means of connecting elements having at least one thread and inserted into the bores of the at least one cylinder head and the cylinder block and bolted to form clamping forces are.

Furthermore, the invention relates to a method for limiting and reducing the mechanical stress of the seal of such an internal combustion engine.

The utility model application DE 1 890 019 U describes an internal combustion engine of the type mentioned. The German Offenlegungsschrift DE 26 54 787 A1 describes a hydraulic tensioner for a cylinder head bolt.

An internal combustion engine of the type mentioned is used for example as a motor vehicle drive. In the context of the present invention, the term internal combustion engine includes diesel engines and gasoline engines, but also hybrid internal combustion engines, which use a hybrid combustion process, and hybrid drives, which in addition to the internal combustion engine comprise an electric motor which can be electrically connected to the internal combustion engine, which receives power from the internal combustion engine or as switchable auxiliary drive additionally delivers power.

Internal combustion engines have at least one cylinder head, which is used to form the at least one cylinder, d. H. the at least one combustion chamber, is connected to a cylinder block, wherein bores are provided for connecting in the cylinder head and in the cylinder block. As part of the assembly of the cylinder block and the cylinder head are arranged by stacking their mounting sides in such a way to each other that the holes are aligned. By means of connecting elements, for example screws or threaded rods, which are inserted and screwed into the bores of the cylinder head and the cylinder block, a frictional connection is then formed.

The cylinder block has a corresponding number of cylinder bores for receiving the pistons or the cylinder tubes. The pistons are guided axially movably in the cylinder tubes and, together with the cylinder tubes and the cylinder head, form the combustion chambers of the internal combustion engine. Consequently, a combustion chamber is mitbegrenzt each of a piston, a cylinder tube and the cylinder head and mitgestaltet. To seal the combustion chambers, a seal is usually arranged between the cylinder block and the cylinder head.

The cylinder head usually serves to accommodate the valve trains. To control the charge cycle, an internal combustion engine requires controls and actuators to operate the controls. As part of the change of charge, the exhaust of the combustion gases via the outlet openings and the filling of the combustion chamber via the inlet openings of the cylinder takes place. To control the charge cycle, four-stroke engines use almost exclusively lift valves as control members which perform an oscillating lifting movement during operation of the internal combustion engine and in this way release and close the inlet openings and outlet openings. The required for the movement of a valve valve actuating mechanism including the valve itself is referred to as a valve train. A valve actuating device regularly comprises a camshaft, wherein overhead camshafts, d. H. Camshafts, which lie above the parting line between the head and the block, are mounted on the cylinder head.

The intake pipes leading to the intake ports and the exhaust pipes connecting to the exhaust ports are at least partially integrated in the cylinder head in the prior art. The exhaust ports of the exhaust ports are regularly merged, often into a single overall exhaust line, and preferably to form an integral exhaust manifold within the cylinder head.

Downstream of the manifold, the exhaust gases are optionally supplied to the turbine of an exhaust gas turbocharger and / or one or more exhaust aftertreatment systems.

In supercharged by turbocharger internal combustion engines, the aim is to arrange the turbine as close to the outlet of the engine to optimally use in this way the exhaust enthalpy of the hot exhaust gases, which is largely determined by the exhaust pressure and the exhaust gas temperature and to ensure a quick response of the turbocharger ,

On the other hand, the way the hot exhaust gases to the various exhaust aftertreatment systems should be as short as possible, so that the exhaust gases are given little time to cool and the exhaust aftertreatment systems reach their operating temperature or light-off as soon as possible, especially after a cold start of the engine.

In order to achieve the aforementioned objects, the exhaust pipes of the cylinders are preferably combined to form at least one integrated exhaust manifold within the cylinder head, i. H. the exhaust manifold is fully integrated into the cylinder head. Such a cylinder head is also characterized by a very compact design, which allows a dense packaging of the entire drive unit. In addition, it is possible to participate in an optionally provided in the cylinder head liquid cooling, in the way that the manifold does not have to be made of thermally highly durable and thus costly materials.

The use of a cylinder head with integrated manifold also leads to a smaller number of components and consequently to a reduction in costs, in particular the installation and deployment costs.

The cylinder head of a modern internal combustion engine is usually subject to higher thermal loads and therefore also places increased demands on the cooling, in particular if the cylinder head is equipped with an integrated exhaust manifold and / or the internal combustion engine is a supercharged internal combustion engine.

If the internal combustion engine has liquid cooling, a plurality of coolant channels or at least one coolant jacket are generally formed in the cylinder head, which or which guide the coolant through the cylinder head, resulting in a more complex cylinder head structure.

The above statements make it clear that the cylinder head of an internal combustion engine is a thermally and mechanically highly loaded component. It should be noted in this context that an increasing proportion of internal combustion engines - by turbocharger supercharger or mechanical supercharger - is charged. Due to the increasingly dense packaging in the engine compartment and the increasing integration of components and components in the cylinder head, for example, the integration of the exhaust manifold, in particular increases the thermal load of the engine or the cylinder head, so to make increased demands on the cooling.

In spark-ignited internal combustion engines, moreover, the required ignition device, in direct-injection internal combustion engines beyond the injection device can be arranged in the cylinder head.

To form a satisfactory, d. H. the combustion chambers sealing connection of the cylinder head and cylinder block are to provide sufficient and sufficiently large holes, which affects the structural design of the particular cylinder head and makes it difficult.

The clamping forces, which are to initiate the formation of a frictional gas-tight connection by means of the connecting elements in the structure, burden the cylinder head, but in particular the seal between the cylinder head and the cylinder block considerably.

On the other hand, the clamping forces must be sufficiently large in all circumstances, d. H. To ensure a gas-tight leak-free seal under all operating conditions of the internal combustion engine.

The arranged between the cylinder block and the cylinder head gasket must seal not only in a cold internal combustion engine in a satisfactory manner, but also in a heated internal combustion engine, in which the individual engine components have more or less heated and expanded. The cylinder block and the at least one cylinder head regularly thermally expand as a result of heat input as the connecting elements, which increase the clamping forces in the compounds during warming up or increase further with increasing operating temperature.

Also to be considered are the different load conditions of the internal combustion engine. Higher loads or higher cylinder pressures and peak pressures during combustion require higher clamping forces to ensure a gas-tight connection of the cylinder head and cylinder block.

In this context, it is of particular relevance whether the internal combustion engine is a supercharged internal combustion engine. In supercharged internal combustion engines, the air required for the combustion process is compressed, whereby each cylinder per cycle a larger air mass can be supplied. As a result, the fuel mass and thus the medium pressure can be increased. The cylinder pressures in general and the peak pressures during combustion in particular are significantly higher than in a comparable naturally aspirated engine.

Therefore desirable are measures with which the mechanical load of the seal arranged between the cylinder block and the cylinder head can be meaningfully limited or reduced.

In view of the above, it is an object of the present invention to provide an internal combustion engine according to the preamble of claim 1, wherein the mechanical load of the arranged between the cylinder block and the at least one cylinder head seal is reduced or reduced.

Another object of the present invention is to provide a method for limiting and reducing the mechanical stress of the gasket of such an internal combustion engine.

• – zwischen dem Zylinderblock und dem mindestens einen Zylinderkopf eine Dichtung vorgesehen und eingespannt ist, und
• – in dem Zylinderblock und dem mindestens einen Zylinderkopf Bohrungen vorgesehen sind, wobei der mindestens eine Zylinderkopf und der Zylinderblock mittels Verbindungselementen miteinander verbunden sind, die mindestens ein Gewinde aufweisen und in die Bohrungen des mindestens einen Zylinderkopfes und des Zylinderblocks eingeführt und unter Ausbildung von Spannkräften verschraubt sind,

und die dadurch gekennzeichnet ist, dass mindestens ein mehrteiliges Verbindungselement vorgesehen ist, bei dem ein Kopfteil des Verbindungselements via einer mit Hydraulikflüssigkeit gefüllten Druckkammer mit einem Schaft des Verbindungselements in kraftübertragender Weise gekoppelt ist, wobei

• – der Schaft an einem dem Kopfteil zugewandten Ende einen Steuerkolben aufweist, der in der Druckkammer translatorisch verschiebbar angeordnet und gelagert und stirnseitig von einem Druck der Hydraulikflüssigkeit druckbeaufschlagt ist, und
• – die Spannkraft zwischen dem Zylinderblock und dem mindestens einen Zylinderkopf unter Verwendung der Hydraulikflüssigkeit veränderbar ist.

The first sub-task is solved by an internal combustion engine with at least one cylinder head, which has at least one cylinder and is connected to a mounting side with a cylinder block to form clamping forces, in the

• - Between the cylinder block and the at least one cylinder head, a seal is provided and clamped, and
• - Are provided in the cylinder block and the at least one cylinder head bores, wherein the at least one cylinder head and the cylinder block are interconnected by means of connecting elements having at least one thread and inserted into the bores of the at least one cylinder head and the cylinder block and bolted to form clamping forces are,

and which is characterized in that at least one multi-part connecting element is provided, in which a head part of the connecting element is coupled via a pressure chamber filled with hydraulic fluid to a shaft of the connecting element in a force-transmitting manner, wherein

• - The shaft has a control piston at an end facing the head part, which is arranged and stored translationally displaceable in the pressure chamber and the end face of a pressure of the hydraulic fluid is pressurized, and
• - The clamping force between the cylinder block and the at least one cylinder head using the hydraulic fluid is variable.

According to the invention, the clamping force, which is introduced by means of a connecting element in the connection of the cylinder head and cylinder block, change or specifically set and control. For this purpose, a multi-part connecting element is used and a hydraulic fluid is used. The connecting element according to the invention is designed in several parts, d. H. modular, and comprises at least two parts, namely a head and a shaft.

The head part is coupled via a pressure chamber as a force-transmitting intermediate element with the shaft and indeed in such a way that the connecting the cylinder head and the cylinder block connecting element can form and exert a clamping force.

The shaft has a control piston, which is arranged translationally displaceable in the pressure chamber and is acted upon by hydraulic fluid on one side. The hydraulic fluid wets the control piston and pressurizes it. According to the invention but not worked with an overpressure of the hydraulic fluid, d. H. not with a pressure above the ambient pressure or atmospheric pressure, but according to the vacuum principle. Namely, if hydraulic fluid is discharged from the pressure chamber, this shifts the control piston in the direction of the head part and the connecting element is shortened or stretched by increasing the clamping force in the connection. The head part is in a sense connected via the hydraulic fluid frictionally connected to the shaft.

The clamping force between the cylinder block and the at least one cylinder head is changed in this way by using the hydraulic fluid and by varying the hydraulic pressure.

The clamping force can thus be adjusted as needed, d. H. control, or influence in an advantageous manner. In particular, the clamping force can be adapted to different operating conditions of the internal combustion engine, so that at any time a gas-tight leak-free sealing of the at least one combustion chamber is ensured and at the same time the mechanical load between the cylinder block and the cylinder head arranged seal is meaningfully limited or reduced.

Different load conditions of the internal combustion engine can be accommodated by a different sized clamping force. The same applies to different cylinder pressures or different peak pressures during combustion. The latter is particularly relevant for supercharged internal combustion engines in which, in principle, a higher medium pressure exists or is realized.

The clamping force in the connecting element or in the connection can be increased by means of hydraulic fluid with increasing load and reduced with decreasing load.

Also different engine temperatures can be considered. The clamping force can be reduced, for example, with increasing engine temperature and increased with decreasing engine temperature. Thus, the effect can be taken into account, according to which the cylinder block or the cylinder head when heated thermally expands more than a connecting element and the clamping force increases as a result of progressive heating, ie increased.

The provision according to the invention of at least one multi-part connecting element makes it possible to mechanically stress the seal arranged between the cylinder block and the cylinder head only to the extent necessary to ensure a gas-tight, leak-free sealing of the at least one combustion chamber.

With the internal combustion engine according to the invention, the first object underlying the invention is achieved, namely provided an internal combustion engine according to the preamble of claim 1, in which the mechanical load between the cylinder block and the at least one cylinder head arranged seal is lower or is reduced.

The pressure chamber is variable in volume. Preferably, the pressure chamber in the direction of the longitudinal axis of the connecting element can be increased or decreased, d. H. lengthen or shorten.

Further advantageous embodiments of the internal combustion engine are discussed in connection with the subclaims.

Embodiments of the internal combustion engine in which the hydraulic fluid is oil are advantageous. Oil is in internal combustion engines regularly one of several operating fluids used and thus already available. In addition, unlike water, oil is harmless in terms of harmful corrosion.

Embodiments of the internal combustion engine in which the hydraulic fluid is engine oil are advantageous.

In internal combustion engines with an oil circuit, therefore, embodiments are also advantageous in this context, which are characterized in that the pressure chamber with the oil circuit of the internal combustion engine is at least connectable. Then, the engine oil circuit may serve to supply the pressure chamber with the oil, and a circulating pump may be used to provide the required oil pressure. The intended pump must be able to provide a sufficiently high oil pressure in the oil circuit or sufficiently high negative pressure to evacuate the pressure chamber.

To supply various consumers with oil, an internal combustion engine is equipped with an oil pump. The pump supplies via the supply line to form an oil circuit regularly a main oil gallery, leading from the channels to the bearings of a crankshaft, with engine oil. Frequently, the cylinder block forms the upper half of the crankcase, which is supplemented by the oil sump serving as the lower crankcase half.

Embodiments of the internal combustion engine may also be advantageous in which the pressure chamber has an independent oil circuit which preferably separates from the oil circuit of the internal combustion engine, ie. H. is disconnected.

Embodiments of the internal combustion engine in which a supply line opens into the pressure chamber are advantageous.

In this context, embodiments in which a shut-off element is arranged in the supply line are advantageous.

The following embodiments have the at least one multi-part connecting element to the object, which can be of very different shape and can be installed in different ways.

Embodiments of the internal combustion engine in which the head part of the at least one connecting element is a nut are advantageous.

Also advantageous are embodiments of the internal combustion engine, in which the head part of the at least one connecting element is a screw head.

The screw head or the nut can be supported on the cylinder head, on the cylinder block or on the pressure chamber bounding walls to build up and initiate the clamping force.

Embodiments of the internal combustion engine in which the shaft of the at least one connecting element is a threaded rod which has at least one end and at least sections a thread are advantageous.

Embodiments of the internal combustion engine in which the at least one connecting element passes through a bore of the at least one cylinder head and with it are advantageous a thread in the cylinder block is bolted to form clamping forces.

Also advantageous are embodiments of the internal combustion engine, in which the at least one connecting element passes through a bore of the cylinder block and is screwed with a thread in the at least one cylinder head to form clamping forces.

In addition, embodiments of the internal combustion engine can be advantageous, in which the at least one connecting element passes through a bore of the cylinder block and a bore of the at least one cylinder head and is bolted using the at least one thread to form clamping forces.

If the at least one connecting element is designed in the manner of a threaded rod, this connecting element can have a thread at both ends and form the clamping force using nuts screwed on.

If the at least one connecting element is designed in the manner of a screw, this connecting element can have a thread at one end and form the clamping force using a screwed-on nut.

Embodiments of the internal combustion engine may be advantageous in which the pressure chamber is arranged on the cylinder head side.

Embodiments of the internal combustion engine may be advantageous in which the pressure chamber is integrated in the cylinder head.

The second sub-task, namely to show a method for limiting and reducing the mechanical load of the gasket of an internal combustion engine of the type described above, is achieved by a method in which the clamping force between the cylinder block and the at least one cylinder head by means of a variation of the hydraulic pressure in the Pressure chamber located hydraulic fluid is changed.

What has already been said for the internal combustion engine according to the invention also applies to the method according to the invention, which is why at this point in general reference is made to the statements made with regard to the internal combustion engine.

The hydraulic fluid wets the control piston and pressurizes it. According to the invention works on the vacuum principle with the hydraulic fluid. Namely, for the purpose of evacuating the pressure chamber, hydraulic fluid is supplied from the pressure chamber to displace the control piston in the direction of the head part and to expand the shaft while increasing the tension force in the connection, a negative pressure is formed to form an evacuating suction. In this respect, the clamping force is changed by means of a variation of the hydraulic pressure of the hydraulic fluid in the pressure chamber.

Process variants are therefore also advantageous, in which the clamping force between the cylinder block and the at least one cylinder head is increased by lowering the hydraulic pressure of the hydraulic fluid in the pressure chamber.

Advantageous may be process variants in which the clamping force is increased with increasing load of the internal combustion engine.

According to the above process variant, the clamping force is adjusted as needed, d. H. controlled. In the present case, the clamping force is adapted to different loads of the internal combustion engine. The aim is a clamping force which is sufficiently large to ensure a seal of the at least one combustion chamber, but mechanically loaded only between the cylinder block and the cylinder head to the required minimum dimension, d. H. is limited. Different loads of the internal combustion engine require different sized clamping forces.

Also advantageous may be process variants in which the clamping force is reduced with increasing engine temperature and increased with decreasing engine temperature. This takes into account the different thermal expansion of the engine components.

Also advantageous may be process variants in which the clamping force increases with increasing engine temperature and is reduced with decreasing engine temperature. This takes into account the correlation or correlation between load and engine temperature. A high engine temperature is regarded as an indication of a high load and interpreted.

In the following the invention is based on an embodiment according to 1 described in more detail. Hereby shows:

1 schematically a multi-part connecting element of a first embodiment of the internal combustion engine.

1 schematically shows a multi-part connecting element 1 A first embodiment of the internal combustion engine to illustrate the principle of operation of this multi-part connecting element 1 ,

The illustrated connection element 1 is modular and includes a headboard 1a and a shaft 1b ,

The headboard 1a is via a pressure chamber 2 as an intermediate element with the shaft 1b connected or coupled. The shaft 1b has a control piston 1c in the pressure chamber 2 is arranged translationally displaceable and one side of hydraulic fluid 3 is charged. The present as hydraulic fluid 3 used engine oil 3a wets the control piston 1c and acts on this spool 1c with pressure.

The headboard 1a of the connecting element 1 is thus using engine oil 3a with the shaft 1b of the connecting element 1 force transmitting and non-positively connected. It works on the vacuum principle. The clamping force between the cylinder block and the at least one cylinder head is using the oil 3a variable.

Will be oil 3a via supply line 4 from the pressure chamber 2 promoted out, this shifts the spool 1c in the direction of the headboard 1a and the connecting element 1 is stretched by increasing the clamping force in the connection.

LIST OF REFERENCE NUMBERS

1

 Connecting element, multi-part connecting element

1a

 Head part of the connecting element

1b

 Shaft of the connecting element

1c

 spool

2

 pressure chamber

3

 hydraulic fluid

3a

 Oil, engine oil

4

 Supply line, connection to the oil circuit

Claims (13)

An internal combustion engine having at least one cylinder head, which has at least one cylinder and is connected to a mounting side with a cylinder block to form clamping forces, in which - between the cylinder block and the at least one cylinder head a seal is provided and clamped, and - in the cylinder block and the at least one cylinder head bores are provided, wherein the at least one cylinder head and the cylinder block by means of connecting elements ( 1 ) are connected to each other, which have at least one thread and inserted into the bores of the at least one cylinder head and the cylinder block and bolted to form clamping forces, characterized in that at least one multi-part connecting element ( 1 ) is provided, in which a head part ( 1a ) of the connecting element ( 1 ) via one with hydraulic fluid ( 3 ) filled pressure chamber ( 2 ) with a shaft ( 1b ) of the connecting element ( 1 ) is coupled in a force-transmitting manner, wherein - the shaft ( 1b ) at a headboard ( 1a ) end facing a control piston ( 1c ), which in the pressure chamber ( 2 ) arranged translationally displaceable and stored and the front side of a pressure of the hydraulic fluid ( 3 ) is pressurized, and - the clamping force between the cylinder block and the at least one cylinder head using the hydraulic fluid ( 3 ) is changeable. Internal combustion engine according to claim 1, characterized in that the hydraulic fluid ( 3 ) Oil ( 3a ). Internal combustion engine according to claim 2, characterized in that the hydraulic fluid ( 3 ) Engine oil ( 3a ). Internal combustion engine according to claim 3 with an oil circuit, characterized in that the pressure chamber ( 2 ) Is at least connectable to the oil circuit of the internal combustion engine. Internal combustion engine according to one of the preceding claims, characterized in that the head part ( 1a ) of the at least one connecting element ( 1 ) is a mother. Internal combustion engine according to one of claims 2 to 4, characterized in that the head part ( 1a ) of the at least one connecting element ( 1 ) is a screw head. Internal combustion engine according to one of the preceding claims, characterized in that the shaft ( 1b ) of the at least one connecting element ( 1 ) is a threaded rod. Internal combustion engine according to one of the preceding claims, characterized in that the at least one connecting element ( 1 ) passes through a bore of the at least one cylinder head and is screwed with a thread in the cylinder block to form clamping forces. Internal combustion engine according to one of claims 1 to 7, characterized in that the at least one connecting element ( 1 ) passes through a bore of the cylinder block and with a Thread in which at least one cylinder head is bolted to form clamping forces. Internal combustion engine according to one of claims 1 to 7, characterized in that the at least one connecting element ( 1 ) passes through a bore of the cylinder block and a bore of the at least one cylinder head and is bolted using the at least one thread to form clamping forces. Method for limiting and reducing the mechanical load of the internal combustion engine gasket according to one of the preceding claims, characterized in that the clamping force between the cylinder block and the at least one cylinder head is adjusted by means of a variation of the hydraulic pressure in the pressure chamber ( 2 ) hydraulic fluid ( 3 ) is changed. A method according to claim 11, characterized in that the clamping force between the cylinder block and the at least one cylinder head by lowering the hydraulic pressure in the pressure chamber ( 2 ) hydraulic fluid ( 3 ) is increased. A method according to claim 12, characterized in that the clamping force is increased with increasing load of the internal combustion engine.

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