Liquid-cooled internal combustion engine

Abstract

The present invention relates to a liquid-cooled internal combustion engine comprising an engine block, which includes a plurality of cylinders, and cylinder heads closing the cylinders, wherein each cylinder is surrounded by a respective cooling liner and each cylinder head has provided therein at least one separate cooling chamber connected to the cooling liner of the associated cylinder via at least one transition channel, wherein the transition channels of at least two cylinders are interconnected via a pressure compensation chamber.

Claims

1. A liquid-cooled internal combustion engine comprising an engine block, which includes a plurality of cylinders, and cylinder heads closing the cylinders, wherein each of the cylinders is surrounded by a respective cooling liner, each of the cylinder heads has provided therein at least one separate cooling chamber connected to the cooling liner of the associated one of the cylinders via at least one transition channel, the transition channels of at least two of the cylinders are directly connected via a pressure compensation chamber, and a flow path of a coolant for each cylinder extends from the at least one separate cooling chamber of the cylinder head to the cooling liner of the cylinder.

2. The liquid-cooled internal combustion engine according to claim 1, wherein the pressure compensation chamber is integrated in the engine block, said pressure compensation chamber extending especially in a longitudinal direction of the engine block and abutting tangentially on the cooling liners of the cylinders.

3. The liquid-cooled internal combustion engine according to claim 1, wherein a distributing chamber is provided, which is adapted to be connected to an external pressure source via a pressure connection and which communicates with the at least one separate cooling chamber of each of the cylinder heads via at least one channel, so that the coolant can flow from the distributing chamber into the at least one separate cooling chamber.

4. The liquid-cooled internal combustion engine of claim 3, wherein the distributing chamber is integrated in the engine block.

5. The liquid-cooled internal combustion engine according to claim 1, wherein at least one collecting chamber is provided, which is connected to the cooling liner of each of the cylinders via one or a plurality of channels, so that the coolant can flow from each of the cooling liners of the engine block into the collecting chamber.

6. The liquid-cooled internal combustion engine of claim 5, wherein the collecting chamber is integrated in the engine block.

7. The liquid-cooled internal combustion engine according to claim 1, wherein at least two transition channels are provided per cylinder head, said at least two of the transition channels extending in parallel from the cylinder head.

8. The liquid-cooled internal combustion engine according to claim 7, wherein said at least two of the transition channels extend from the at least one cooling chamber to the pressure compensation chamber.

9. The liquid-cooled internal combustion engine according to claim 1, wherein a main flow path of the coolant for each of the cylinders extends from a distributing chamber via an upper cooling subchamber into a lower cooling subchamber, from where it extends via the at least one transition channel to the pressure compensation chamber, and from the pressure compensation chamber via the cooling liner into a collecting chamber.

10. The liquid-cooled internal combustion engine according to claim 1, wherein a main flow path of the coolant for each of the cylinders extends from a distributing chamber via a lower cooling subchamber into an upper cooling subchamber, from where it extends via the at least one transition channel to the pressure compensation chamber, and from the pressure compensation chamber via the cooling liner into a collecting chamber.

11. The liquid-cooled internal combustion engine according to claim 1, wherein the cylinder heads define a cylinder bank, which is produced as a cast part, at least a part of the separate cooling chambers communicating with one another via a vent line integrated in the cylinder heads and the cylinder bank.

12. The liquid-cooled internal combustion engine according to claim 1, wherein gasket elements of cylinder head gaskets through which partial flows of the flow a path of the coolant between each of the cylinder heads and the engine block flow are configured identically for all the cylinders.

13. The liquid-cooled internal combustion engine according to claim 1, wherein each of the cooling liners is subdivided into at least two cooling subliners, and the cooling subliners are connected in parallel to the pressure compensation chamber and/or a collecting chamber.

14. The liquid-cooled internal combustion engine according to claim 13, wherein a connection exists between the cooling liners of neighboring cylinders.

15. The liquid-cooled internal combustion engine of claim 13, wherein each of the cooling liners is subdivided into a lower and an upper cooling subliner.

16. A liquid-cooled internal combustion engine comprising an engine block, which includes a plurality of cylinders, and cylinder heads closing the cylinders, wherein each of the cylinders is surrounded by a respective cooling liner, each of the cylinder heads has provided therein at least one separate cooling chamber connected to the cooling liner of the associated cylinder via at least one transition channel, the transition channels of at least two of the cylinders are directly connected via a pressure compensation chamber, and at least two of the separate cooling chambers are provided for each of the cylinder heads, and are interconnected via at least one connection channel.

17. The liquid-cooled internal combustion engine according to claim 16, wherein at least one exhaust duct extending through each of the cylinder heads is, at least sectionwise, fully surrounded by the separate cooling chambers of the cylinder head, as well as the connection channels.

18. The liquid-cooled internal combustion engine according to claim 16, wherein an upper and a lower cooling subchamber are provided.

19. The liquid-cooled internal combustion engine of claim 18, wherein at least one exhaust duct extending through each of the cylinder heads is fully surrounded by the upper and the lower cooling subchambers.

20. The liquid-cooled internal combustion engine according to claim 16, wherein the at least two of the separate cooling chambers are interconnected via at least two of the connection channels with different diameters.

21. A liquid-cooled internal combustion engine comprising an engine block, which includes a plurality of cylinders, and cylinder heads closing the cylinders, wherein each of the cylinders is surrounded by a respective cooling liner, each of the cylinder heads has provided therein at least one separate cooling chamber connected to the cooling liner of the associated cylinder via at least one transition channel, the transition channels of at least two of the cylinders are directly connected via a pressure compensation chamber, and at least one bypass extends from at least one of the separate cooling chambers of each of the cylinder heads, and terminates in a collecting chamber, to provide a bypass flow path that circumvents the cooling liner.

22. The liquid-cooled internal combustion chamber of claim 21, wherein said at least one bypass extends from a lower cooling subchamber.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantages and characteristics of the present invention will be explained hereinafter in more detail making reference to two embodiments that are shown in the figures, in which:

(2) FIG. 1 shows a schematic representation of the coolant flow path through an internal combustion engine according to the prior art;

(3) FIG. 2 shows a schematic representation of the cooling volumes of an engine block and a cylinder bank according to the present invention;

(4) FIG. 2a shows a schematic representation of a cylinder liner in the cooling volumes;

(5) FIG. 2b shows a schematic representation of a distributing chamber in the cooling volumes;

(6) FIG. 2c shows a schematic representation of a lower cooling subchamber in the cooling volumes;

(7) FIG. 2d shows a schematic representation of an upper cooling subchamber in the cooling volumes;

(8) FIG. 3 shows a schematic representation of the coolant flow paths through the internal combustion engine as disclosed by the present invention, according to the top-down concept;

(9) FIG. 4 shows a top view of a subarea of the internal combustion engine according to the present invention;

(10) FIG. 5 shows a sectional view according to section axis D-D according to FIG. 4 through the internal combustion engine as disclosed by the present invention, according to the top-down concept;

(11) FIG. 6 shows a sectional view according to section axis E-E according to FIG. 4 through the internal combustion engine as disclosed by the present invention, according to the top-down concept;

(12) FIG. 7 shows a further sectional view through the internal combustion engine as disclosed by the present invention, according to the top-down principle;

(13) FIG. 8 shows a schematic representation of the flow path pattern of an alternative internal combustion engine as disclosed by the present invention, according to the bottom-up concept;

(14) FIG. 9 shows a sectional view through the internal combustion engine according to the bottom-up concept along section axis D-D according to FIG. 4;

(15) FIG. 10 shows a sectional view along section axis E-E according to FIG. 4 through the internal combustion engine, according to the bottom-up concept, and

(16) FIG. 11 shows a further sectional view of the internal combustion engine according to the bottom-up concept.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(17) In the following, two embodiments of the internal combustion engine according to the present invention are presented, which allow good balancing of the partial flows of coolant through the coolant chambers, channels and liners to be assigned to the individual cylinders of the engine. By means of FIG. 2, the structural design of the coolant chambers, channels and liners will first be illustrated, taking a six-cylinder in-line engine as an example. Two concrete embodiments will then be described making reference to FIGS. 3 to 7 and 8 to 11.

(18) FIG. 2 does not show any structural components of the internal combustion engine according to the present invention, but illustrates only the coolant volumes existing within the engine block and the cylinder head bank when the engine is in operation. Channels, cooling chambers and cooling liners are normally created by suitable openings in the cast part of the engine block or the cylinder bank. The cooling liner for each cylinder is created e.g. by a larger diameter of the cylinder-shaped opening for receiving therein the cylinder sleeve, so that the resultant gap defines the volume in question. A total of six cylinder liners 10 are shown in line.

(19) Each cooling liner 10 is divided into an upper subliner 11 and a lower subliner 12, the volume of the upper cooling subliner 11 being considerably smaller than the volume of the lower cooling liner 12 (cf. FIG. 2a). An elongate collecting chamber 50 laterally adjoins the cooling liners 10 of a cylinder bank of the engine block and is fluidically connected in parallel with both cooling subliners 11, 12. On the cylinder side located opposite the collecting chamber 50, a pressure compensation chamber 60 is provided, which also extends along the cylinder bank in the longitudinal direction of the engine block. Also this pressure compensation chamber 60 is in fluid communication with the upper and lower cooling subliners 11, 12.

(20) For each cylinder, a lower cooling subchamber 20 is provided in the cylinder head above the cooling liners 10. A detailed representation is shown in FIG. 2c. The four circular openings 21 are conditioned by the valves installed in the cylinder head, in particular by two air intake valves as well as two exhaust valves, around which the coolant of the cooling volume of the cooling subchamber 20 flows. The central opening 22 is conditioned by the sleeve of a fuel injector installed in the cylinder head.

(21) The upper cooling subchamber 30 of the cylinder bank is located thereabove and can be seen in detail in FIG. 2d.

(22) Reference numeral 40 stands for the distributing chamber 40 (FIG. 2b). The latter additionally extends in a vertical direction up to the upper cooling subchamber 30, so that the coolant contained in the distributing chamber 40 can directly flow, in partial flows, into the upper cooling subchambers 30 of the cylinders. It follows that a top-down cooling concept is here used. The meaning of said concept will be described hereinafter in more detail with reference to the embodiments. In addition, fluid connections 70 between the upper cooling subchambers 30 are recognizable. The resultant vent duct is identified by reference numeral 70.

(23) The individual connections of the coolant volumes and the corresponding flow paths will be discussed hereinafter on the basis of the concrete cooling concepts. The so-called top-down concept of the internal combustion engine according to the present invention is shown exemplarily in FIG. 3 for a four-cylinder engine. The representation shows a cylinder bank of the engine block 100, whose cylinder heads are combined so as to form a cylinder head bank 200. For the sake of simplicity, the reference numerals are only indicated for the first cylinder, the additional cylinders being, however, configured identically with the first cylinder.

(24) Starting from the distributing chamber 40 into which the coolant is pumped via an external pressure connection 41, the coolant is split up into individual partial flows, each of which flows directly into the upper cooling subchamber 30 via a channel 31. The cooling subchambers 30 of the cylinder heads are interconnected via the vent duct 70, whereby air bubbles contained in the coolant can be collected and discharged to the outside. The ends of the vent line are closed by means of end-side caps or provided with a suitable vent valve.

(25) Most of the coolant contained in the upper cooling subchamber 30 of each cylinder flows via a main flow path 28 into the lower cooling subchamber 20. A comparatively small part of the volume flows via the additional fluid connection 27 to the lower chamber 20. Via the second fluid connection 27 additional venting is accomplished when the engine is in operation. In addition, the risk of undesirable accumulations of air in the cooling system, in particular when the engine is put into use, i.e. when the engine is being filled with coolant, can be reduced.

(26) The lower cooling subchamber 20 communicates via two parallel transition channels 25, 26 with the pressure compensation chamber 60. All the partial flows of the individual cylinders are thus reunited in the pressure compensation chamber 60. The existence and the structural design of this pressure compensation chamber 60 leads to good balancing of the cooling system, and production-dependent asymmetries of the channels 28, 31 and of the cooling subchambers 20, 30 are compensated for and almost identical coolant flow rates are obtained for the partial flows of the cylinders. Hence, a largely identical cooling performance is achieved for all the cylinders, whereby the power demand for circulating the coolant will decrease. A modification of the cylinder head gaskets is therefore superfluous. Moreover, the suggested flow pattern allows the asymmetries to be already compensated for to a certain extent through the vent duct 70.

(27) Downstream of the pressure compensation chamber 60, the coolant is again split up into individual partial flows for the individual cylinders and flows via the parallel connection lines 61, 62 to the upper and lower subliners 11, 12 of the cooling liner 10 of the individual cylinders in the engine block 100. After having flown around the cylinder sleeve, the coolant returns into the collecting chamber 50, which delivers the coolant via the pressure connection 51 to the part of the coolant circuit located outside the internal combustion engine. It will be advantageous to feed the upper and lower cooling subliners 11, 12 in parallel from the pressure compensation chamber 60, since a serial connection would entail significantly higher pressure losses because the whole amount of coolant required for cooling the large surface of the lower cooling subliner would have to flow through the upper cooling subliner, which has a much smaller flow cross-section. And the comparatively small flow cross-section of the upper cooling subliner has a length corresponding to half the diameter of the cylinder sleeve.

(28) The lower cooling liners 12 of neighboring cylinders are in fluid communication via the channel 13, so as to distribute the pressure pulsations caused during the expansion phase to neighboring partial coolant flows in order to prevent a development of cavitation damage.

(29) Additionally, the lower cooling subchamber 20 of each cylinder is connected via a bypass channel 29 directly to the collecting chamber 50, whereby a smaller part of the volume of the partial flow will flow past the cooling liner 10 and directly into the collecting chamber 50. Also this measure helps avoiding the risk of dead areas and recirculation of the coolant flow, so as to achieve primarily a reliable and effective cooling and secondarily a reduction of pressure losses.

(30) The sectional views according to FIGS. 5, 6 and 7 through the engine block 100 and the cylinder bank 200 following hereinafter show the concrete characteristics of the individual coolant chambers, liners and channels. The sectional views of FIGS. 5 and 6 cut the engine block on the level of a cylinder in different planes, which are shown in FIG. 4 as sectional planes D-D and E-E.

(31) FIG. 5 shows a section along axis D-D. The cylindrical opening of the engine block 100 has installed therein the cylinder sleeve 101. The gap existing between the opening wall and the sleeve defines the cooling liner, which fully surrounds the cylinder sleeve 101. The opening in the cast part of the engine block 100 has different diameters in a longitudinal direction, whereby the upper and lower cooling subliners 11, 12 are formed. It can here be seen that the lower cooling subliner 12 is much longer, when seen in the longitudinal direction of the cylinder, and that the volume of the cooling subliner 12 is much larger than the volume of the upper cooling subliner 11. In addition, it can be seen that the cross-sectional area of the lower cooling subliner 12 is much larger than that of the upper cooling subliner 11. Furthermore, it can be seen that also the pressure compensation chamber 60 is formed within the engine block 100 and abuts tangentially on the openings for the cylinder sleeves 101 in the direction of the longitudinal axis of the engine block 100.

(32) The cylinder bank 200 attached to the engine block 100 comprises the upper as well as the lower cooling subchamber 20, 30. An installed injector 201 can be seen also in this case. The depicted arrows identify the main flow direction of the coolant flow of a single cylinder. Accordingly, the coolant is conducted from the distributing chamber 40 to the upper cooling subchamber 30 and from there it continues to flow via the main channel 28 to the lower cooling subchamber 20. The second connection line 27 between the upper and lower cooling subchambers 20, 30 is clearly visible, said second connection line having a much smaller diameter.

(33) Via the transition channels 25, 26, only one of which is visible in the sectional plane, the coolant flows into the pressure compensation chamber 60 and from there to the individual cooling subliners 11, 12. The circle on the longitudinal axis of the cylinder sleeve 101 symbolizes the existing fluid connection 13 between the lower subliner 12 and neighboring cooling liners 10. What cannot be seen in the sectional plane D-D is the connection existing between the cooling liners 11, 12 and the collecting chamber 50. This connection can, however, be seen in FIG. 6. Also the necessary connection between the pressure compensation chamber 60 and the cooling liners 11, 12 can here be seen.

(34) A further sectional view of the explained cooling concept is shown in FIG. 7. In this plane, a cylinder exhaust duct extending in a transverse direction through the cylinder head bank can be seen in a cross-sectional view, said exhaust duct being, at least sectionwise, fully surrounded by the coolant flow of a cylinder. The upper and lower cooling subchambers 20, 30 as well as the respective channel connections contribute to coolingly surround the exhaust duct 202. The gasket 203 seals the upper cooling subchamber 20 towards the top. FIG. 7 also shows the bypass connection 29 from the lower cooling subchamber 20 to the collecting chamber 50. Likewise, the vent duct 70, which is directly integrated in the cylinder head bank, can be seen.

(35) An alternative cooling concept for the internal combustion engine according to the present invention can be seen from the representations according to FIGS. 8 to 11. For the sake of simplicity, the reference numerals in the representation of FIG. 8, which comprises a total of four cylinders, are only indicated for the first cylinder, the additional cylinders being, however, configured identically with the first cylinder. It goes without saying that also this alternative cooling concept can be transferred to engines having a different number of cylinders, again clearly independently of whether the engine in question is an in-line engine or a V-type engine. Other than in the case of the embodiment according to FIGS. 2 to 7, the coolant does here not flow from the distributing chamber 40 into the upper cooling subchamber 30 of the cylinder head bank 200, but, instead, it flows first into the lower cooling subchamber 20, from where it continues to flow via the connection channels 27, 28 into the upper cooling subchamber 30. The latter communicates via a single transition channel 25 with the pressure compensation chamber 60 from which partial flows to the individual cylinder liners are provided, as is also the case in the first embodiment.

(36) Also in this embodiment, the lower cooling subchamber 20 has a bypass connection 29 to the collecting chamber 50, so that the path via the upper cooling subchamber 30 as well as the cooling liner 10 can be circumvented through said bypass. Also this bypass includes a portion having a comparatively small cross-section. However, this narrow cross-section is only provided over a very short length, whereas the lengths of the flow paths at the cooling subliners of reduced cross-section are many times longer, said flow paths representing a correspondingly high flow resistance. FIG. 9, 10 show corresponding sectional views along the section axes D-D as well as E-E. In comparison with the first embodiment and FIGS. 5 and 6, it can here be seen that the structural design of the engine block 100 is identical, whereas minor differences will be necessary in the cylinder bank 200. It follows that, for using the various cooling concepts and flow patterns, a uniform engine block 100 may be used, and only specific cylinder heads will be necessary.