Cylinder arrangement and method of cooling the cylinder arrangement

Abstract

Cylinder arrangement (1) and method for cooling the cylinder arrangement (1) addresses a solution with which the heat transfer from a combustion chamber (6) of an internal combustion engine located in a cylinder liner (2) of the cylinder arrangement (1) into a region (7) surrounding the cylinder liner (2), such as a cylinder block or crankcase, is controlled in a temperature-dependent manner. Arrangement solves said problem by providing a jacket (9), the expansion of which changes depending on temperature, arranged between the cylinder liner (2) and the region (7) surrounding the cylinder liner (2). The method uses the cylinder liner (2) with a jacket (9), expands depending on temperature and surrounds the cylinder liner (2); jacket (9) forms a gap (10) between jacket (9) and region (7) in a first temperature range; jacket (9) forms no gap (10) between jacket (9) and region (7) in a second temperature range.

Claims

1. A cylinder arrangement (1), comprising a cylinder liner (2) for receiving a piston (3) and a region (7) surrounding the cylinder liner (2), wherein a jacket (9) having an expansion that changes as a function of temperature is arranged between the cylinder liner (2) and the region (7) surrounding the cylinder liner (2), and that the jacket (9) forms a gap (10) in a first temperature range and does not form a gap (10) in a second temperature range, wherein the gap is disposed in the first temperature range between the jacket (9) and the surrounding region (7).

2. The arrangement according to claim 1, wherein the jacket (9) has a different thermal expansion coefficient than the cylinder liner (2).

3. The arrangement according to claim 1, wherein the jacket (9) has a thermally active construction.

4. The arrangement according to claim 3, wherein the jacket (9) is composed of a bi-metal or a shape memory alloy.

5. The arrangement according to claim 1, wherein an arrangement for actively changing radial expansion or circumference of the jacket (9) as a function of temperature is arranged on the jacket (9).

6. The arrangement according to claim 5, wherein the arrangement for actively changing the radial expansion or the circumference of the jacket (9) comprises an electrically, piezoelectrically or magnetically operated actuator.

7. The arrangement according to claim 1, wherein a surface area of physical contact between the jacket (9) and the cylinder liner (2) remains unchanged in both the first temperature range and the second temperature range.

8. The arrangement according to claim 1, wherein the first temperature range is between −20° C. and 100° C. and the second temperature range is between 100° C. and 140° C.

9. The arrangement according to claim 1, wherein the gap (10) is filled with a gas.

10. The arrangement according to claim 9, wherein the gas is air.

11. A method for cooling a cylinder arrangement (1), comprising the steps of: providing a cylinder liner (2) for receiving a piston (3) and a region (7) surrounding the cylinder liner (2); and transferring heat generated in a combustion chamber (6) of the cylinder liner (2) to the region (7) surrounding the cylinder liner (2), wherein the cylinder liner (2) is provided with a jacket (9) which surrounds the cylinder liner (2) and has an expansion that changes as a function of temperature, the jacket (9) forms in a first temperature range a gap (10) between the jacket (9) and the region (7) and the jacket (9) does not form a gap (10) between the jacket and the region (7) in a second temperature range.

12. The method according to claim 11, wherein the jacket (9) has a thermal expansion coefficient that is different from the thermal expansion coefficient of the cylinder liner (2) and causes a change in radial expansion or circumference of the jacket (9).

13. The method according to claim 12, wherein the jacket (9) is provided with a thermally active construction which causes a change in the radial expansion or the circumference of the jacket (9), wherein the thermally active construction is provided with a bi-metal or a shape memory alloy.

14. The method according to claim 12, wherein the jacket (9) is provided with an arrangement for actively changing of the radial expansion or the circumference of the jacket (9) as a function of temperature.

15. The method according to claim 14, wherein the temperature-dependent, active change in the radial expansion or the circumference of the jacket (9) takes place by way of an electrically, piezoelectrically or magnetically operated actuator.

16. The method according to claim 11, wherein the first temperature range is between −20° C. and 100° C. and the second temperature range is between 100° C. and 140° C.

17. The method according to claim 11, wherein a surface area of physical contact between the jacket (9) and the cylinder liner (2) remains unchanged in both the first temperature range and the second temperature range.

18. The method according to claim 11, wherein the gap (10) is filled with a gas.

19. The method according to claim 18, wherein the gas is air.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1: a cylinder arrangement according to the invention in a first temperature range, and

(2) FIG. 2: a cylinder arrangement according to the invention in a second temperature range.

DETAILED DESCRIPTION OF THE INVENTION

(3) FIG. 1 shows the cylinder arrangement 1 according to the invention, which is arranged in an internal combustion engine, in a first temperature range. This first temperature range occurs, for example, in a phase in which the cylinder arrangement 1 is cold and the internal combustion engine has not yet reached a so-called operating temperature. Such state occurs, for example, when the internal combustion engine is started.

(4) The cylinder arrangement 1 includes a cylinder liner 2 in which a piston 3 moves along the running surface 4. The piston 3 is connected in the usual way to a crankshaft (not shown) via the connecting rod 5. The combustion chamber 6, which is formed by a cylinder head (not shown) disposed above the cylinder liner 2, is arranged above the piston 3.

(5) The running surface 4 has a wear-resistant surface. The piston 3, which can advantageously be provided with piston rings (not shown in FIG. 1), moves over this running surface 4.

(6) In order not to adversely influence the play between piston 3 and cylinder liner 2 during a warm-up phase of the internal combustion engine, the assemblies may have a similar coefficient of thermal expansion.

(7) The cylinder liner 2 is surrounded by a jacket 9 which, for example, surrounds the entire cylinder liner 2. The cylinder liner 2 with its jacket 9 is surrounded by a region 7 which is subsequently intended to be a cylinder block 7 or a cylinder crankcase, for example.

(8) Such a region or cylinder block 7 may have channels 8 through which a cooling fluid flows. Such cooling fluid improves heat transfer during operation of the internal combustion engine, because the cooling fluid extracts heat from the cylinder block 7.

(9) In the first temperature range or state of the internal combustion engine, during a starting phase, the temperature of the internal combustion engine and of the cylinder arrangement 1 is low. In this phase, which is also referred to as the cold state of the internal combustion engine, the internal combustion engine has, for example, a temperature similar to that of its surroundings. Depending on the weather, this temperature can be, for example, in the range from −20° C. to 100° C., in particular in a range from −15° C. to 30° C.

(10) In this first temperature range, a gas-filled gap 10 is formed between the jacket 9, the cylinder liner 2 and the cylinder block 7. Such a gas can be air, for example. This gas-filled gap 10 has an insulating effect, meaning that the heat transfer between the cylinder liner 2 and the cylinder block 7 is severely limited or reduced. In this case, the heat transfer between the jacket 9, the cylinder liner 2 and the cylinder block 7 is limited to convection and heat radiation in the gap 10 and is thus greatly reduced.

(11) The reduction in the heat transfer causes the cylinder liner 2 with the piston 3 to warm up faster, so that an operating temperature of the cylinder arrangement 1 can be reached more quickly than with an arrangement without an air gap 10.

(12) Upon reaching the operating temperature, the running properties of the internal combustion engine and its efficiency improve. In addition, the working temperature required for a catalytic converter to function efficiently, the so-called “light-off temperature”, is reached earlier. This obviates, for example, the need for additional devices required in catalytic converters to quickly reach their working temperature, or their operating time can be greatly reduced. Thus, cost and/or energy savings can be expected. Such an additionally necessary device in a catalytic converter may be, for example, an electrical heater.

(13) Advantageously, quickly reaching the operating temperature of the internal combustion engine or the working temperature of the catalytic converter saves fuel.

(14) FIG. 2 shows a cylinder arrangement 1 according to the invention in a second temperature range or state.

(15) This second state is, for example, a phase in which the internal combustion engine with the cylinder arrangement 1 is warm and has reached the operating temperature. Such a state occurs, for example, when the internal combustion engine has been operating after a warm-up time of a few minutes, for example. It is known that this time is also dependent on the load or loading of the internal combustion engine.

(16) FIG. 2 shows the cylinder arrangement 1 of the cylinder liner 2, in which the piston 3 moves along the running surface 4. The piston 3 is connected in a conventional manner to a crankshaft (not shown) via the connecting rod 5. The combustion chamber 6, which is formed by a cylinder head (not shown) arranged above the cylinder liner 2, is arranged above the piston 3.

(17) The cylinder liner 2 is surrounded by the jacket 9, with the jacket 9 being enclosed by the cylinder block 7. The illustration of FIG. 2 also shows schematically channels 8 in the cylinder block 7, through which a coolant can flow during the operation of the internal combustion engine.

(18) In contrast to FIG. 1, the jacket 9 has changed in such a way that a gap 10 is no longer formed between the jacket 9 and the cylinder block 7. In this case, the heat generated during the combustion in the combustion chamber 6 can also be dissipated via the cylinder liner 2 and the jacket 9 in the cylinder block 7. In this second temperature range or state, heat can be transferred between the jacket 9 of the cylinder liner 2 and the cylinder block 7 through heat conduction and heat dissipation of the internal combustion engine is thus much greater than in the first temperature range.

(19) The coolant flowing through the channels 8 is provided to dissipate the heat from the cylinder block 7. The coolant circulates in a conventional coolant circuit of an internal combustion engine and thus contributes to the heat transfer from the cylinder block 7.

(20) In a first variant, the jacket 9 may be composed of a material that has a thermal expansion coefficient different from that of the cylinder liner 2. Thus, with a suitable choice of the thermal expansion coefficient, the jacket 9 may, due to its thermal expansion and thus depending on the temperature in a first cold state of the first temperature range, form a gap 10 towards the cylinder block 7. In a second temperature range having a higher temperature, such as the operating temperature of the internal combustion engine, the jacket 9 closes the gap 10 due to its thermal expansion.

(21) In a second variant, the jacket 9 may have a thermally active construction which changes the expansion of the jacket 9 as a function of temperature. For this purpose, for example, bi-metals or a shape memory alloy are used in the jacket 9 or in the region of the jacket 9. Such a jacket 9 forms in a first temperature range or a state of low temperature a corresponding gap 10. In a second temperature range or state of higher temperature, the bi-metals or the shape memory alloy of the jacket 9 expand, closing the gap 10, for example at a defined temperature.

(22) In a further variant, the jacket 9 may have an active adjustment designed to control the expansion of the jacket 9, for example in its radial direction or its circumference. For this purpose, actuators with a corresponding adjustment device for the jacket 9 can be used. Such actuators can be operated, for example, electrically, piezoelectrically or magnetically, and thus change the gap 10 as a function of temperature.

(23) The principle and structure described for the jacket 9 can also be applied to the regions of the cylinder head of the internal combustion engine or the pistons 3.

(24) According to the invention, it is thus possible to control the warm-up of an internal combustion engine by specifically influencing the possible heat transfer from the combustion chamber 6 via the cylinder liner 2 to the cylinder block 7. Quickly reaching the working temperature of a catalytic converter of the internal combustion engine is ensured by reducing the heat transfer in a first temperature range or a state of low temperature.

(25) Particular advantages of the present invention are listed below: With the cylinder arrangement according to the invention, an improved warm-up of an internal combustion engine is achieved, since in a first temperature range of a warm-up phase the heat losses, i.e. the dissipation of heat generated in the combustion chamber of the cylinder arrangement, for example to the cylinder block or a cylinder crankcase, are reduced. Faster warm-up of the components near the combustion chamber is possible. Shift of the energy distribution towards the exhaust gas and associated higher exhaust gas temperatures to reach the light-off temperature more quickly. Fuel savings. Further advantages for the operation at low ambient temperatures and in the low-load range. Better mixture formation occurs faster due to a shorter warm-up phase. Emissions decrease as the light-off temperature is reached more quickly.

LIST OF REFERENCE SYMBOLS

(26) 1 Cylinder arrangement 2 Cylinder liner 3 Piston 4 Running surface 5 Connecting rod 6 Combustion chamber 7 Region around the cylinder liner (cylinder block/cylinder crankcase) 8 Channels 9 Jacket 10 Gap