WO2015026282A1

WO2015026282A1 - Cylinder lining and engine with such cylinder lining

Info

Publication number: WO2015026282A1
Application number: PCT/SE2014/050888
Authority: WO
Inventors: Jessica ELFSBERG; Stig-Olof CARLÉN; Peter Eriksson
Original assignee: Scania Cv Ab
Priority date: 2013-08-21
Filing date: 2014-07-11
Publication date: 2015-02-26
Also published as: SE1350962A1; SE537333C2; DE112014003350B4; DE112014003350T5

Abstract

A cylinder liner defines a combustion chamber (6) in a cylinder of a combustion engine and has a metallic body (8) with an inner wall (7) bounding the combustion chamber, a circumferential inner recess (13) in the inner wall and a metal ring (15) which is received in the recess (13), and has a surface (16) facing the combustion chamber, adapted to protrude into the combustion chamber (6) relative to said inner wall (7) of the cylinder liner's body. The metal ring (15) is glued to the cylinder liner's body in the recess with a glue (22) which has a heat conductivity less than 50% of the heat conductivity of the material of the cylinder liner's body (8).

Description

CYLINDER LINING AND ENGINE WITH SUCH CYLINDER

LINING

TECH N ICAL AREA OF TH E I NVENTION

The present invention pertains to a cylinder liner, designed to define a combustion chamber in a cylinder of a combustion engine, wherein the cylinder liner comprises

• a metallic body with an inner wall bounding the combustion chamber,

• a circu mferential internal recess inside said inner wall , said recess being located in the area of one end of the cylinder liner's body, adapted to be connected with a cylinder lid , and being nearer to this end than a piston ring of a piston moving backwards and forwards, receivable in a combustion chamber, is intended to reach, and

• a metal ring which is received in the recess and has a surface facing the combustion chamber, which surface is designed to protrude into the combustion chamber relative to said inner wall of the cylinder liner's body,

• and a combustion engine according to the preamble of the enclosed independent combustion engine claims.

Thus the invention is not limited to a cylinder liner for any spe- cific type of combustion engine or fuel , and diesel and ethanol may be mentioned as a couple of non-exhaustive examples of fuel . The invention also pertains to cylinder liners for combustion engines designed for all types of use, such as in industrial applications, crushing machines and in various types of motor vehi- cles, even though the invention is particularly applicable to wheeled motor vehicles, especially commercial vehicles, such as trucks and buses, and will for this reason sometimes be discussed in this application with the objective of elucidating , but not limiting , the invention.

BACKGROU N D TECHNOLOGY

A cylinder liner of the type defined above has a said metal ring, which is called a saver ring within the area of technology, in or- der for coke, forming on the upper part of the piston above the uppermost piston ring during the combustion in the combustion chamber, to be scraped off the piston to protect the surface on the inner wall of the cylinder liner's body. The body of the cylinder liner obtains a high temperature during the operation of the combustion engine in which it is comprised, and it is normally cooled with coolant between the latter and an engine block surrounding the combustion engine's cylinders. However, this coolant must not reach the end of the cylinder liner at the cylinder head, so that the cylinder liner in this area abuts against the engine block, and normally a seal in the form of a circu mferential O-ring made of an elastic material is arranged between the cylinder liner and the engine block in this area. This means that the cylinder liner in this area may not be cooled at all , or only to a small extent, by the coolant between the cylinder liner and the engine block.

US 201 3/0055993 A1 shows a cylinder liner which as such lacks said metallic ring and for this reason is not of the type defined above, but which has an insulating material externally, e.g . a ce- ramie material , in said area designed to be arranged nearest the cylinder head of a cylinder. This insulating layer will entail a reduced heat transfer from the cylinder liner's body to a surrounding engine block in this area, but it will not result in a lower tem- perature of the cylinder liner in this area, and the heat insulating material is indicated to be arranged to increase the engine's efficiency.

Naturally, efforts are constantly made to improve the features of a cylinder liner of the type defined above, in order to i mprove the features of a thus equipped combustion engine.

SUM MARY OF TH E I NVENTION The objective of the present invention is to provide a cylinder liner of the type described above, which is improved in at least one respect in relation to prior art cylinder liners.

This objective is achieved according to the invention , by provid- ing such a cylinder liner with the features listed in the characterising portion of claim 1 .

By gluing the metal ring against the cylinder liner's body with a glue with such low heat conductivity, a thermal barrier is created between the metal ring and the body of the cylinder liner. This means that the body of the cylinder liner in this area, nearest to said end next to a cylinder head, during operation , i .e. combustion in the combustion chamber, will have a lower temperature than would be the case if the metal ring , such as in prior art technology, were to be loose in the recess facing the cylinder liner's body. This is particularly important since the cylinder liner's body is more difficult to cool in this area than further away from said end, and the thermal barrier will result in a reduced temperature where normally a said O-ring is arranged . In cylin- ders with cylinder liners of the type defined above, such O-rings must be made of a very expensive type of rubber, tolerating the high temperatures, up to around 1 50 °C, to which the O-ring is subjected. Still , such O-rings must be replaced after a certain period of operation of the combustion engine. Through the ar- rangement of the glue and thus the thermal barrier between the metal ring and the cylinder liner's body according to the invention , such a temperature reduction at the location of the arrangement of said O-ring may, however, achieve that the O-ring will not need to be replaced at all , so that both the cost of the O- ring itself and of the service stop may be saved.

Another advantage of the arrangement of said glue is that the dead volu me between the metal ring and the body of the cylinder liner will be replaced with glue, and thus not contribute to the production of emissions of pollutants during the combustion in the combustion chamber. Thus, the total dead volume in this region of the combustion chamber is reduced, and thus the level of said emissions may be reduced. According to one embodiment of the invention, said glue has a heat conductivity which is less than 1 0%, less than 5% or less than 2% of the heat conductivity of the material in the body of the cylinder liner. By using a glue with such a low heat conductivity, a said thermal barrier is achieved with a "high height" between the metal ring and the body of the cylinder liner, along with the advantages of the existence of such a barrier mentioned above. Thus, according to another embodiment of the invention , said glue has a heat conductivity which is less than 5 W/mK at 20 °C or less than 2 W/mK at 20 °C.

According to another embodiment of the invention, said glue is a ceramic glue. A ceramic glue has a very low heat conductivity in relation to the metallic cylinder liner body, and will therefore constitute a desired barrier between the metal ring and the body of the cylinder liner.

According to another embodiment of the invention, the metal ring is glued to the cylinder liner's body with a glue layer with a thickness of 0.05- 1 mm. Such a thickness of the glue layer is suffi- cient to achieve a desired thermal barrier.

According to another embodi ment of the invention, the cylinder liner's body is, as is usual , made of cast iron. According to another embodi ment of the invention, the cylinder liner's body has a circumferential external track-like recess in the area of said end, adapted to receive an O-ring made of an elastic material with a cross-sectional diameter, which, when under no load , is greater than the depth of the track-like recess. The exis- tence of the thermal barrier formed through the layer of glue is particularly advantageous at an arrangement of a said O-ring in the area in question , as it leads to the advantages discussed above, resulting from a reduction of the temperature to which the O-ring is subjected. The invention also provides a combustion engine, which is equipped with the features in the characterising portion of the enclosed independent combustion engine claims. The advantages of such a combustion engine and embodi ments thereof de- fined in the non-independent claims are made clear in the discussion above, regarding the cylinder liner according to the invention.

The invention also pertains to a motor vehicle according to claims 1 2 and 1 3.

Other advantageous features and advantages with the invention are set out in the description below. BRI E F DESCRI PTION OF TH E DRAWI NG

Below are descriptions of an example embodiment of the invention with reference to the enclosed drawing, in which : Fig . 1 is a partly sectional view of a part nearest the cylinder head of a cylinder in a combustion engine, equipped with a cylinder liner according to one embodiment of the invention . DETAI LE D DESCRI PTION OF AN EM BODI M ENT ACCORDI NG TO TH E I NVENTION

Fig . 1 shows a section of a part of a cylinder 1 in a combustion engine 2, here in a motor vehicle M , the cylinder of which is equipped with a cylinder liner 3 according to one embodiment of the invention . Specifically, that part of the cylinder is displayed, which is located in the vicinity of its cylinder head 4, which defines one end 5 of a combustion chamber 6 delimited by an inner wall 7 of a body 8 of the cylinder liner.

In the combustion chamber, a piston 9 is received to move forwards and backwards, and the piston 9 abuts against and is controlled by said inner wall 7 via piston rings 1 0- 1 2. The cylinder liner's body 8 has a circu mferential inner recess 1 3 in the inner wall 7 in the area of one end 1 4 of the cylinder liner, adapted to be connected with the cylinder lid 4 and nearer this end than any piston ring, specifically the upper piston ring 1 2, is intended to reach . A metal ring 1 5, a so-called saver ring, is re- ceived in the recess 1 3 and has a surface 1 6 facing the combustion chamber, which surface is adapted to protrude into the combustion chamber relative to the inner wall 7, in order to thus scrape away coke formed during combustion from the piston's end section 1 7, when this part of the piston passes the metal ring 1 5.

The cylinder liner 3 is surrounded by an engine block 1 8, and between the cylinder liner and the engine block there is a space 1 9, which in the direction toward said end 1 4 of the cylinder liner ex- tends up to the area of said end and is designed for the circulation of coolant therein , for cooling of the cylinder liner and thus also the engine block. The cylinder liner's body 8 has a circu mferential external tracklike recess 20 arranged in said area and in which an O-ring 21 made of an elastic material , such as rubber, especially fluorine rubber, is received to abut against the cylinder block during com- pression, and thus to seal and prevent coolant in the space 1 9 from reaching closer to the end 1 4 than up to the O-ring 21 .

The special feature of the present invention is that the metal ring 1 5 is glued to the cylinder liner with a glue that has a low heat conductivity, e.g. in the range of less than 5% of the heat conductivity of the cylinder liner's material , which is cast iron. This glue forms a glue layer 22 indicated in the figure, with e.g . a thickness of a few tenths of a millimetre, which may be compared with the thickness of the metallic ring, which may e.g. be in the range of 3-6 mm. Herein , the glue layer is advantageously formed of a ceramic glue, such as the two-component glue based on metasilicate and fine-grained alu miniu m oxide marketed by the company Keranova AB under the name K- 1 400. The glue layer 22 fills up a part of, and thus reduces, the dead volume of the cylinder's combustion chamber, so that the emission level of pollutants as a result of the combustion in the combustion chamber is reduced, but in particular, the glue layer forms a thermal barrier between the metallic ring 1 5 and the cyl- inder liner's body 8, so that the latter will have a lower temperature at the place where the O-ring 21 is received than it would have in the absence of the glue layer. This may entail that the O- ring 21 , which may be made of a relatively expensive material such as fluorine rubber in order to tolerate the high tempera- tures, could be used without being replaced during the entire life of the combustion engine, and no longer needs to be replaced after a certain period of operation of the combustion engine, as in the case where the combustion engine is integrated in a motor vehicle and the motor vehicle is serviced after a certain driving distance.

The invention is obviously not limited in any way to the embodiment described above, but numerous possible modifications thereof should be obvious to a person skilled in the area, without such person departing from the spirit of the invention as defined by the appended claims.

Claims

1 . Cylinder liner designed to define a combustion chamber (6) in a cylinder of a combustion engine, wherein the cylinder liner comprises

• a metallic body (8) with an inner wall bounding (7) the combustion chamber,

• a circumferential internal recess (1 3) inside said inner wall , said recess being located in the area of one end (1 4) of the cylinder liner's body, adapted to be connected with a cylinder lid (4) , and nearer to this end than a piston ring ( 1 0- 1 2) of a piston moving forwards and backwards (9) , receivable in a combustion chamber, is intended to reach, and

• a metal ring (1 5) which is received in the recess (1 3) and has a surface (1 6) facing the combustion chamber, which surface is adapted to protrude into the combustion chamber (6) relative to said inner wall (7) of the cylinder liner's body,

characterised in that said metal ring (1 5) is glued to the cylinder liner's body in the recess with a glue (22) having a heat conductivity less than 50% of the heat conductivity of the material of the cylinder liner's body (8) .

2. Cylinder liner according to claim 1 , characterised in that said glue has a heat conductivity which is less than 1 0%, less than 5% or less than 2% of the heat conductivity of the material in the body of the cylinder liner.

3. Cylinder liner according to claim 1 or 2, characterised in that said glue has a heat conductivity less than 5 W/mK at 20 °C or less than 2 W/mK at 20 °C.

4. Cylinder liner according to any of the previous claims, characterised in that said glue is a ceramic glue.

5. Cylinder liner according to any of the previous claims, characterised in that the metal ring (1 5) is glued to the cylinder liner's body (8) with a layer of glue (22) with a thickness of 0.05- 1 mm.

6. Cylinder liner according to any of the previous claims, characterised in that the body of the cylinder liner (8) is made of cast iron.

7. Cylinder liner according any of the previous claims, charac- terised in that the cylinder liner's body has a circumferential external track-like recess (20) in the area of said end, adapted to receive an O-ring (21 ) made of an elastic material with a cross-sectional diameter, which, when under no load, is greater than the depth of the track-like recess.

8. Combustion engine, characterised in that it comprises at least one cylinder (1 ) with a cylinder liner (3) according to any of claims 1 -7.

9. Combustion engine according to claim 8, characterised in that it comprises an engine block (1 8) which circumferentially abuts to the cylinder liner's body (8) , surrounding the cylinder liner (3) in an area next to said end (1 4) of the combustion chamber (6) , a space (1 9) between the cylinder liner and the engine block, which in the direction towards said end extends up to said area and is designed for circulation of coolant therein , an O-ring (21 ) made of an elastic material arranged between the cylinder liner (3) and the engine block (1 8) in said area, in order to seal and prevent coolant in said space from reaching closer to the end than up to the O-ring.

1 0. Combustion engine according to claim 9, characterised in that the O-ring (21 ) is made of rubber.

1 1 . Combustion engine according to claim 1 0, characterised in that the O-ring (21 ) is made of fluorine rubber.

1 2. Motor vehicle, characterised in that it comprises a combustion engine (2) according to any of claims 9- 1 1 .

1 3. Motor vehicle according to claim 1 2, characterised in that it is a wheeled motor vehicle, such as a truck or a bus.