DE102016115512A1 - Cylinder crankcase for an internal combustion engine with plastic housing and metal insert - Google Patents

Abstract

The invention relates to a cylinder crankcase for an internal combustion engine with a plastic housing (12) and one of the plastic housing (12) at least partially surrounded metal insert (14), wherein in the metal insert (14) at least one cylindrical combustion chamber (16) is formed , wherein in an area enclosed by the metal insert (14) and / or by the plastic housing (12) an isolation space (26) is provided.

Description

The invention relates to a cylinder crankcase for an internal combustion engine according to the preamble of claim 1.

Taking into account an increasing downsizing of internal combustion engines, in particular reciprocating internal combustion engines, as well as a hybridization of motor vehicle drives, not only mechanical, but also many thermal challenges arise. Targeted heat transport or heat storage can be of great importance for achieving a long-lasting drive.

Among other things, it is designed to reduce weight and noise US 4,848,292 A It is known to form a cylinder head and a cylinder crankcase, each referred to as an engine block, each of a fiber-reinforced phenolic resin and a metal insert embedded therein. Between the metal insert and the phenol resin sheath, a cooling jacket for heat dissipation is formed.

Out US 5,083,537 A is also known as an engine block cylinder crankcase known which comprises a cylinder shell made of metal and a surrounding this in the radial direction fiber-reinforced plastic housing. The cylinder jacket has a radial projection, which is followed by the plastic housing. In a region between the cylinder jacket and the plastic housing, a cooling channel is formed.

A potential disadvantage is that these cylinder crankcases can quickly cool again after heating to operating temperature, which may be particularly disadvantageous in connection with the use of start-stop systems and / or in conjunction with hybrid drives with only occasional use of the internal combustion engine.

The invention has for its object to provide a cylinder crankcase with reduced weight available, which is improved in terms of heat transfer.

The object is achieved according to the invention with the features of the independent claim. Further practical embodiments and advantages of the invention are described in connection with the dependent claims.

A cylinder crankcase according to the invention for an internal combustion engine comprises a plastic housing and a metal insert surrounded by the plastic housing, wherein at least one cylindrical combustion chamber is formed in the metal insert. In an area enclosed by the metal insert and / or by the plastic housing, at least one isolation space is provided, the insulating space being considered to be any cavity surrounding a volume which reduces the heat transfer from the combustion space to the outside towards the environment, i. the thermal conductivity of the insulation space should be reduced, preferably in relation to all materials adjacent to the insulation space. In particular, a vacuum may be provided in the insulation space, or a suitable thermal insulation medium may be arranged in the insulation space, so that the insulation space has a low thermal conductivity, in particular a maximum thermal conductivity of 0.2 W / mK, more preferably maximum 0.1 W / mK and more preferably at most 0.05 W / mK. By forming at least one insulation space in the cylinder crankcase according to the invention, the combustion chamber is thermally shielded from the environment. As a result, the operating temperature of the internal combustion engine, in particular the temperature of oil used, achieved faster, which has a positive effect on the tribological systems in the engine. There is less friction and wear and thus lower losses and a longer life of the internal combustion engine. The thermal insulation additionally causes a delay of the cooling of the internal combustion engine at a temporary shutdown and thus an already elevated temperature at a restart of the internal combustion engine. The latter is particularly advantageous for an increasingly used start-stop automatic and in conjunction with hybrid drive systems. A further advantage of a cylinder crankcase according to the invention is that a region enclosed by the metal insert and / or by the plastic housing can be realized in a structurally simple manner and thus with only a small additional manufacturing cost in order to create one or more isolation spaces. In this case, the insulation space in its radial width and its axial height and the filling of the insulation space (type of thermal insulation medium) can be flexibly adapted to different cylinder crankcase sizes. Supplementary insulating layers, which surround the entire cylinder crankcase, can be completely omitted in this case, or at least reduced in their dimensions, so that a cylinder crankcase according to the invention is comparatively compact. As a result, the package of the internal combustion engine does not have to be adapted, even in the case of a subsequent addition of insulation spaces. Furthermore, small cylinder pitches and transverse bolt spacings can be realized, in particular if the isolation spaces are arranged exclusively annularly around all combustion chambers or in each case one "combustion chamber row" (for example in the case of V engines or W engines with a plurality of "combustion chamber rows").

In a practical embodiment of a cylinder crankcase according to the invention radially outer boundary walls of the insulation space are at least partially formed by the metal insert and / or the plastic housing. Preferably, isolation spaces are provided in a region between the metal insert and plastic housing, so that the inner radial boundary wall is formed by the metal insert and the outer radial boundary wall is formed by the plastic housing. In this case, a structurally particularly simple design of an insulation space results by simple radial spacing of the plastic housing to the metal insert. Such an isolation space can also be easily filled before the metal insert is inserted into the plastic housing. However, it is preferred to design the isolation spaces so that they can still be filled after the assembly of a metal insert. If screw domes are formed in the metal insert for a cylinder head screw connection, it is preferred if the boundary walls in the region of the screw domes are made entirely of metal, around clamping forces occurring in the screw connection and acting in the axial direction of the cylinder crankcase exclusively via the metal insert to be able to support.

In another practical embodiment of a cylinder crankcase according to the invention, an inner boundary wall and at least one radial boundary wall, i. an upper boundary wall and / or a lower boundary wall, the at least one insulation space formed by the metal insert, and an outer boundary wall is formed by the plastic housing. Preferably, the inner boundary wall, the upper boundary wall and the lower boundary wall of the insulation space are formed by the metal insert. This embodiment can not only be made simple and inexpensive, but may be particularly advantageous in connection with an additional coolant channel when the upper and / or lower boundary wall are used for the sealing of the coolant channel.

A particularly effective thermal insulation is obtained if the at least one insulation space is designed to surround the combustion chamber in a completely annular manner. Completely annular in this context means that the volume of the corresponding isolation space surrounds the combustion chamber completely and without interruption, at least over part of its height extending in the axial direction. Characterized the combustion chamber over the respective portion of its height in the circumferential direction is completely isolated from the environment. As a result, undesired thermal bridges with resulting heat losses are avoided, and there is an approximately uniform heat distribution and heat retention over the entire circumference of the combustion chamber in the region of the insulation space.

In a further practical embodiment, at least two isolation spaces, which extend over different height ranges, are arranged via the height extending in the axial direction of the combustion chamber. With extending over different height ranges on the one hand - regardless of the relative position of the isolation rooms with respect to a combustion chamber - meant an extension of the isolation rooms on different sized absolute heights, ie. For example, one isolation room has a height of 4 cm and another isolation room has a height of 5 cm. On the other hand, this specification also includes that the insulation spaces can be arranged relative to the combustion chamber such that they are arranged, as seen in the axial direction, non-overlapping, ie. For example, an isolation space may be provided in an upper area of the combustion chamber, and another isolation space may be provided in a lower area of the combustion space. By forming two or more isolation rooms, the thermal insulation can be adjusted as needed, for example, to realize a different thermal insulation or insulation in a region of a subsequent cooling channel in the radial direction and in a region without a cooling channel.

For a particularly simple manufacture and assembly of a cylinder crankcase according to the invention, it is advantageous if at least one projection extending in the radial direction is formed on the metal insert. Such a projection preferably extends over the entire circumference of the metal insert. Preferably, two projections spaced apart in the axial direction are formed on the metal insert, which extend over at least part of the height of the combustion chamber, preferably also over the entire circumference. The plastic housing may in this case be arranged adjacent to the projections of the metal insert in order to limit an insulation space. The plastic housing may in this case also, for example by gluing or otherwise, be additionally connected in the area of the contact surfaces to the metal insert with this, in particular if this - for example, to improve the insulation effect or for securing a in the insulation space arranged medium - is advantageous. Projections are not only an advantageous way to surround the insulation space from three sides with a boundary wall made of a metal material, wherein a projection of the upper boundary wall, another projection, the lower boundary wall and an outer wall of the Metal inserts form the radially inner wall of the insulation space. In addition, a projection can also be used for an upper boundary wall or for a lower boundary wall of a cooling channel, in particular a radially inner region of a projection. A cooling channel is advantageously completely formed in the metal insert, and a corresponding isolation space closes in this case in the radial direction outside viewed on the cooling channel, so that between the cooling channel and the insulation space in the axial direction extending intermediate wall is formed, which forms the radially inner boundary wall of the insulation space.

In the insulation space, a thermal insulation medium is arranged or enclosed in a simple and inexpensive to produce embodiment in order to improve the thermal insulation, preferably a solid. It may be included in the isolation room but also a fluid. In particular, air having a thermal conductivity of λ = 0.026 W / mK or inert gases, such as e.g. Krypton, with a thermal conductivity of λ = 0.009 W / mK or argon with λ = 0.018 W / mK in question. In particular, plastic foams made of thermosetting phenolic resin are suitable as solids with heat-insulating properties. In the intended temperature range of the insulation spaces non-flowable solids and air have the advantage that they can be easily introduced into the insulation space and no special measures to seal the insulation space from the environment are required. For the sake of completeness, it is pointed out that a combination of fluids and solids can be arranged in isolation spaces. To fill the isolation rooms with a thermal insulation medium can be formed in the plastic housing optionally closable filling openings. Preferably, however, the filling takes place once during the assembly of a cylinder crankcase according to the invention, in particular after the insertion of the metal insert into the plastic housing.

In order to avoid overheating during continuous operation of the internal combustion engine, a cooling channel may be formed in the metal insert. Such a cooling channel is preferably formed completely in the metal insert. Usually, water or cooling liquid of a cooling circuit is used as the coolant in the cooling channel. The cooling channel extends in particular over part of the height of the combustion chamber, preferably in an upper region of the combustion chamber, which surrounds the thermally most stressed region of the cylinder crankcase. The cooling channel can also extend over the entire height of the combustion chamber, in particular for cooling of internal combustion engines with increased power density and with a consequent increased cylinder cooling demand. In particular, the cooling channel has lateral, at least partially in the radial direction extending coolant inlets, which are also formed in the metal insert. Radially outside the cooling channel and / or viewed in the axial direction above and / or below the cooling channel, at least one isolation space is provided in a cylinder crankcase according to the invention, preferably in an area between the metal insert and the plastic housing.

An isolation space is arranged in a further practical embodiment immediately adjacent to the at least one combustion chamber. Adjacent means in the present case that the insulation space is connected only via a wall of the metal insert with the combustion chamber and thus no cooling channel or other constructive element between the insulation space and the combustion chamber is arranged. By such an arrangement, the combustion chamber is particularly well insulated in a section in which no coolant channels are arranged, since the heat absorbed by the metal insert is largely retained by the insulation space.

Further practical embodiments of the invention are described below in conjunction with the drawings. Show it:

1 an inventive cylinder crankcase with plastic housing and metal insert in a perspective view obliquely from the front,

2 the cylinder crankcase off 1 in a sectional view according to line II-II 1 .

3 the cylinder crankcase off 1 in a sectional view taken along line III-III 1 .

4 the cylinder crankcase off 1 in a sectional view along line IV-IV 1 .

5 just the metal insert out 1 in a side view,

6 the metal insert out 5 in a sectional view according to line VI-VI 5 , and

7 the metal insert out 5 in a sectional view according to line VII-VII from 5 ,

In 1 is an inventive cylinder crankcase 10 shown for an internal combustion engine, with only an upper part of the cylinder crankcase 10 is shown. A lower part of the cylinder crankcase 10 with a crankshaft bearing lane is not shown in the figures, since this part is not relevant to the invention. Such a part can follow in any form.

As in particular in the 2 to 4 can be seen well, includes the cylinder crankcase 10 a plastic housing 12 and one of the plastic housing 12 surrounded metal insert 14 , In the metal insert 14 are present four cylindrical combustion chambers 16 educated. The metal insert 14 is about the height of the combustion chambers 16 - with respect to the center axes of the cylindrical combustion chambers 16 considered - in the radial direction on the outside completely of the plastic housing 12 surround.

As in 2 , a section through one of the combustion chambers 16 is shown, is the combustion chamber 16 from an inner wall 18 of the metal insert 14 surround. In the metal insert 14 is a cooling channel in the embodiment shown 20 educated. As in particular from the 2 to 4 and 6 it can be seen surrounds the cooling channel 20 the combustion chambers 16 viewed in the axial direction in an upper area. The cooling channel 20 is in the embodiment shown between the inner wall 18 and an intermediate wall 22 of the metal insert 14 educated. How out 2 can be seen, is a radially outwardly extending coolant inlet 24 in the metal insert 14 formed, by which coolant, in particular water or another cooling liquid in the cooling channel 20 can flow in. From the cooling channel 20 the coolant can flow into the cylinder head, not shown, in which a - also not shown coolant outlet is formed.

The metal insert 14 is in the illustrated embodiment of the plastic housing 12 surrounded so spaced that two isolation spaces 26 are formed. How out 2 It can be seen that the isolation rooms 26 in the axial and in the radial direction spaced apart such that an upper insulation space 28 viewed in the radial direction is arranged further out than the cooling channel 20 and a lower isolation room 30 immediately adjacent to the combustion chamber 16 is arranged. Both isolation rooms 26 each have an extending in the axial direction inner boundary wall 32 , an upper boundary wall extending in the radial direction 34 and a radially extending lower boundary wall 36 on which through the metal insert 14 are formed. An extending in the axial direction outer boundary wall 38 is in each case by the plastic housing 12 educated.

To form the respective upper boundary walls 34 and the lower boundary walls 36 are on the metal insert 14 three corresponding protrusions 40a . 40b . 40c on - viewed in the axial direction - different height levels of the metal insert 14 educated. At the projections 40a . 40b . 40c is considered in the radial direction outside the plastic housing 12 on the metal insert 14 at. This forms the - viewed in the axial direction - middle projection 40b in each case the lower boundary wall 36 of the upper isolation room 28 and at the same time the upper boundary wall 34 of the lower isolation space 30 , This is not mandatory, but here has the advantage of a dual function.

In the sectional view according to 3 it can be seen that the lower isolation space 30 in a special area completely through the metal insert 14 is formed, ie that in this particular area all boundary walls 32 . 34 . 36 . 38 through the metal insert 14 are formed. As can be seen, the special area is a screw area in which adjacent to the lower isolation space 30 screw bosses 42 are formed with openings extending in the axial direction. These screw domes 42 serve to the above subsequent cylinder head (not shown) with the cylinder crankcase 10 to screw.

The lower isolation room 30 as well as the cooling channel 20 are - viewed in the radial direction - inside of the screw domes 42 arranged. The upper isolation room 28 is in the radial direction further outward than the cooling channel 20 arranged. The inner boundary wall 32 as well as the upper boundary wall 34 and the lower boundary wall 36 of the upper isolation room 28 are at the upper isolation room 28 also in the screw area of the metal insert 14 educated. The outer boundary wall 38 is through the plastic housing 12 educated.

4 shows a section through the four combustion chambers 16 , The combustion chambers 16 are each only through the inner wall 18 of the metal insert 14 separated from each other. The isolation rooms 26 and the cooling channel 20 are accordingly only to the outside, in the direction of the combustion chambers 16 total surrounding surfaces arranged as each outside right and left in 4 can be seen. The upper isolation room 28 is in the radial direction adjacent to the cooling channel 20 , and the lower isolation room 30 is in the radial direction adjacent to the respective outer regions of the combustion chambers 16 educated.

In 5 is only the metal insert 14 without plastic housing 12 shown in a side view. In the upper area are the four coolant inlets 24 educated. The radial projections 40a . 40b . 40c , which each have an upper boundary wall 34 and / or a lower boundary wall 36 the isolation rooms 26 (not shown) extend at different height levels of the metal insert 14 , The combustion chambers 16 surrounding are the mentioned screw domes 42 for screwing the metal insert 14 formed with a cylinder head, not shown.

The geometric arrangement of the isolation rooms 26 or the cooling channel 20 around the four combustion chambers 16 in the metal insert 14 or in the plastic housing 12 will be described below in connection with the 6 and 7 explained in more detail.

In 6 is a section through a horizontal plane shown, in which the upper isolation space 28 and the cooling channel 20 lie. Well recognizable are the four combustion chambers 16 with a circular cross section, which on the outside in each case by the inner wall 18 of the metal insert 14 are limited. Between the inner wall 18 and the partition 22 is the cooling channel 20 formed, which the four combustion chambers 16 on the outside completely and without interruption encloses. Every combustion chamber 16 is from four screw domes 42 surround. Radial outside of the partition 22 or the screw domes 42 closes the upper isolation room 28 which, viewed in the axial direction, exceeds the height level between the projections 40a and 40b extends. The upper isolation room 28 encloses the four combustion chambers 16 also completely ring-shaped and uninterrupted. The upper isolation room 28 points - except for the areas with the screw domes 42 - In cross section in approximately the same shape as the cooling channel 20 and surrounds this annular outside.

7 shows a section through the lower portion of the cylinder crankcase shown 10 with a horizontal plane in which the lower isolation space 30 is trained. The four combustion chambers 16 are also in this area of the inner wall 18 of the metal insert 14 surround. Directly in the radial direction outside on the outside to the inner wall 18 the combustion chambers 16 then the lower isolation room 30 formed, which the four combustion chambers 16 completely and uninterruptedly encloses a ring. In the area of the screw domes 42 is the lower isolation room 30 completely from the metal insert 14 surrounded, that is, here are all four boundary walls 32 . 34 . 36 . 38 from the metal insert 14 educated.

In the upper isolation room 28 and in the lower isolation room 30 If necessary, thermal insulation media can be arranged. In particular, in the upper isolation room 28 in the radial direction adjacent to the cooling channel 20 is arranged from the lower isolation space 30 that is adjacent to the combustion chambers 16 is arranged, different thermal insulation media are arranged.

The features of the invention disclosed in the present description, in the drawings and in the claims may be essential both individually and in any desired combinations for the realization of the invention in its various embodiments. The invention may be varied within the scope of the claims and in consideration of the knowledge of the person skilled in the art.

LIST OF REFERENCE NUMBERS

10

 cylinder crankcase

12

 Plastic housing

14

 Metal insert

16

 combustion chamber

18

 inner wall (of the metal insert)

20

 cooling channel

22

 partition

24

 Coolant inlet

26

 insulation space

28

 upper isolation room

30

 lower isolation room

32

 inner boundary wall

34

 upper boundary wall

36

 lower boundary wall

38

 outer boundary wall

40a, 40b, 40c

 head Start

42

 screw boss

QUOTES INCLUDE IN THE DESCRIPTION

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

Cited patent literature

• US 4848292 A [0003]
• US 5083537 A [0004]

Claims (9)

Cylinder crankcase for an internal combustion engine with a plastic housing ( 12 ) and one of the plastic housing ( 12 ) at least partially surrounded metal insert ( 14 ), wherein in the metal insert ( 14 ) at least one cylindrical combustion chamber ( 16 ) Is formed, characterized in that in one (of the metal insert 14 ) and / or from the plastic housing ( 12 ) enclosed area at least one isolation space ( 26 ) is provided. Cylinder crankcase according to the preceding claim, characterized in that radially outer boundary walls ( 38 ) of the isolation room ( 26 ) at least partially through the metal insert ( 14 ) and / or through the plastic housing ( 12 ) are formed. Cylinder crankcase according to one of the preceding claims, characterized in that an inner boundary wall ( 32 ) and at least one radial boundary wall ( 34 . 36 ) of the at least one isolation space ( 26 ) through the metal insert ( 14 ) are formed and an outer boundary wall ( 38 ) through the plastic housing ( 12 ) is formed. Cylinder crankcase according to one of the preceding claims, characterized in that the at least one isolation space ( 26 ) the combustion chamber ( 16 ) is formed completely annularly enclosing. Cylinder crankcase according to one of the preceding claims, characterized in that in the axial direction of the combustion chamber ( 16 ) extending height at least two isolation rooms ( 28 . 30 ) are arranged, which over different height ranges of the combustion chamber ( 16 ). Cylinder crankcase according to one of the preceding claims, characterized in that on the metal insert ( 14 ) at least one radially outwardly extending projection ( 40a . 40b . 40c ) is trained. Cylinder crankcase according to one of the preceding claims, characterized in that in the insulation space ( 26 ) is at least partially arranged or enclosed a thermal insulation medium. Cylinder crankcase according to one of the preceding claims, characterized in that in the metal insert ( 14 ) a cooling channel ( 20 ) is trained. Cylinder crankcase according to one of the preceding claims, characterized in that the at least one isolation space ( 26 ) immediately adjacent to the at least one combustion chamber ( 16 ) is arranged.

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