Internal combustion engine

Abstract

The invention relates to an internal combustion engine (1) having a cylinder (4) which is provided in a cylinder housing (2) and in which a piston (7) reciprocates in the direction of a cylinder axis (4a) of the cylinder (4) between a lower dead center (UT) and an upper dead center (OT), a first end (8) of the cylinder (4) being associated with the upper dead center ( OT) and a second end (9) of the cylinder (4) being associated with the lower dead center (UT); and a piston cooling device (12) having at least one annular piston cooling channel (16) which is provided in the region of the second end (9) of the cylinder (4) and which has at least one cooling nozzle (15; 151; 152) directed onto a lower surface (70) of the piston (7). In order to allow the piston (7) to be cooled with little effort, the annular piston cooling channel (16) is formed by a channel ring part (13) or is provided in a channel ring part (13) which is inserted or pressed into the cylinder (4), preferably from the side of the first end (8) of the cylinder (4), in the direction of the cylinder axis (4a).

Description

[0001]

[0002] internal combustion engine

[0003] The invention relates to an internal combustion engine with at least one cylinder arranged in a cylinder housing, in which a piston is arranged which moves back and forth in the direction of a cylinder axis of the cylinder between a bottom dead center and a top dead center, wherein a first end of the cylinder is assigned to the top dead center and a second end of the cylinder is assigned to the bottom dead center, with a piston cooling device which has at least one annular piston cooling channel arranged in the region of the second end of the cylinder with at least one cooling nozzle directed towards an underside of the piston.

[0004] In internal combustion engines with at least one piston arranged in a cylinder, some of the combustion heat is absorbed by the at least one piston and the heat absorbed by the piston is mainly transferred to the lubricating oil in the crankcase via piston rings and the, for example, water-cooled cylinder and via the inner surface of the piston.

[0005] While internal combustion engines with low specific power often manage without piston cooling, internal combustion engines with higher specific power, especially high-performance engines, require targeted piston cooling.

[0006] Two types of piston cooling are known: splash cooling and cooling channel cooling. In splash cooling, at least one oil jet is directed onto the inside and / or underside of the piston. In cooling channel cooling, the piston has an annular cavity, which is usually cast into the piston. This cavity forms a cooling channel that is supplied with pressurized oil via an inlet.

[0007] CN 105298612 A discloses an internal combustion engine with a cylinder in which a reciprocating piston is arranged and connected via a connecting rod to a crankshaft located in the crankcase. An annular oil line is arranged in the cylinder within the crankcase of the internal combustion engine. The oil line has a plurality of cooling nozzles distributed around its circumference, which are directed towards the underside of the piston facing the crankcase. Similar arrangements are also known from publications CN 105221231 A, CN 105275569 A, CN 107762611 A, CN 205089433 U, CN 205089434 U, CN 205089435 U and CN 205089436 U. US Patent 2,500,085 A depicts an internal combustion engine with a piston arranged in a cylinder. A ring-shaped spray tube is located in the crankcase area, through which lubricating oil is sprayed onto the inner surface of the cylinder.

[0008] The annular oil line is only shown schematically in the aforementioned prior art. The method of manufacture and fastening is not disclosed.

[0009] US Patent 1,816,516 A describes an internal combustion engine with a cylinder and piston connected via a piston rod to a crankshaft located in a crankcase. At the lower end of the cylinder, facing the crankcase, the cylinder housing has a molded annular groove, which is sealed from the crankcase by a ring screwed into the groove via a thread. The cylinder has a number of radial openings at its lower end, radiating from the piston cooling channel formed by the groove. These radial openings act as cooling nozzles directed towards the underside of the piston. Oil is sprayed onto the underside of the piston above the piston cooling channel and the cooling nozzles to cool the piston. The manufacture and assembly of the piston cooling channel is comparatively complex.

[0010] The object of the invention is to enable cooling of the piston with minimal effort.

[0011] According to the invention, this is achieved by forming the annular piston cooling channel through a channel ring part or by arranging it in a channel ring part which is inserted or pressed into the cylinder - preferably from the side of the first end - in the direction of the cylinder axis.

[0012] The channel ring component is applied to the cylinder from the side of the cylinder head plane towards the cylinder axis. This simplifies installation and also makes subsequent installation or replacement possible.

[0013] To enable precise positioning in the axial direction, it is advantageous if at least one stop – preferably annular – is arranged in the region of the second end of the cylinder, wherein the channel ring portion is inserted into the cylinder in the direction of the cylinder axis until it reaches the stop and rests against it. The channel ring portion can be inserted axially into the cylinder until the end face of the channel ring portion facing the crankcase abuts the stop. This largely eliminates axial misalignment. The stop can be formed by the cylinder housing or by a separate component. In an embodiment of the invention in which a cylinder liner is arranged in the cylinder, which is inserted or pressed in from the side of the first end in the direction of the cylinder axis, the cylinder liner is inserted into the cylinder in the direction of the cylinder axis up to the channel ring portion.Advantageously, the cylinder liner rests on the channel ring section, with the channel ring section preferably being clamped between the stop and the cylinder liner. The channel ring section is thus secured against axial displacement within the cylinder.

[0014] Alternatively, a defined clearance can be provided between the stop and the cylinder liner in the direction of the cylinder axis. This defined clearance prevents heat-induced stresses in the channel ring section and the cylinder liner.

[0015] The arrangement and fastening of the channel ring part according to the invention does not require a screw connection. Therefore, no thread needs to be machined in the cylinder housing. This significantly reduces manufacturing costs compared to arrangements known from the prior art.

[0016] According to the invention, to supply at least one cooling nozzle with oil, the channel ring part has at least one circumferential piston cooling channel, wherein the channel ring part is flow-connected to at least one cooling nozzle.

[0017] Advantageously, at least one piston cooling channel is formed in the channel ring section and preferably by a circumferential groove in the outer surface of the channel ring section. This allows for simple manufacturing.

[0018] One embodiment of the invention provides that the channel ring section has at least two piston cooling channels, wherein preferably a first piston cooling channel and a second piston cooling channel are arranged one above the other in the channel ring section, spaced apart in the direction of the cylinder axis. Because the two piston cooling channels are arranged side by side in the axial direction, a separate oil supply is possible, particularly if at least one piston cooling channel originates from an outer surface of the channel ring section.

[0019] According to one embodiment of the invention, at least one cooling nozzle is arranged in the region of a first end face of the channel ring section facing the piston, or in the channel ring section between the piston cooling channel and the first end face of the channel ring section, preferably being molded into the channel ring section. It is advantageous if the channel ring section has a first cooling nozzle or a first group of first cooling nozzles and a second cooling nozzle or a second group of second cooling nozzles, wherein the first cooling nozzle or the first cooling nozzles extend from the first piston cooling channel and the second cooling nozzle or the second cooling nozzles extend from the second piston cooling channel. This enables effective and demand-based cooling of the piston.

[0020] To achieve effective cooling, at least one piston cooling channel can be flow-connected to a pressure oil supply channel of a pressure oil device arranged in the cylinder housing, wherein preferably the first piston cooling channel is flow-connected to a first pressure oil supply channel and the second piston cooling channel is flow-connected to a second pressure oil supply channel.

[0021] It is particularly advantageous if at least one pressure oil supply channel is switchable and / or controllable, with the first pressure oil supply device and the second pressure oil supply device preferably being switchable and / or controllable independently of each other. This makes it possible to increase or decrease the cooling of the piston as required.

[0022] In order to be able to cool hot spots on the piston in a targeted manner, it is advantageous if at least two cooling nozzles have different jet geometries and / or different jet directions.

[0023] To enable simple and quick installation of the channel ring component with precise positioning, it is advantageous if the channel ring component can be positioned using a positioning device. The positioning device can further be designed to prevent rotation of the channel ring component within the cylinder. For example, the positioning device can have at least one positioning pin engaging in a bore of the channel ring component and / or the cylinder housing, or it can be formed by another positive-locking connection between the channel ring component and the cylinder housing.

[0024] Within the scope of the invention, it is further provided that the cooling ring part is formed by a casting or by an additively or subtractively manufactured part.

[0025] The invention will be explained in more detail below with reference to the non-limiting embodiments shown in the figures. These schematically illustrate:

[0026] Fig. 1 shows an internal combustion engine according to the invention in a longitudinal section through the cylinders; Fig. 2 shows an internal combustion engine according to the invention in a first embodiment in a section through a cylinder along line II - II in Fig. 1;

[0027] Fig. 3 shows an internal combustion engine according to the invention in a second embodiment in a longitudinal section analogous to Fig. 2;

[0028] Fig. 4 shows an internal combustion engine according to the invention in a third embodiment variant in a longitudinal section analogous to Fig. 3;

[0029] Fig. 5 shows a channel ring section of this internal combustion engine in an axonometric view from below; and

[0030] Fig. 6 shows this channel ring part in a bottom view.

[0031] Identical parts are marked with the same reference numbers in the different versions.

[0032] Fig. 1 shows an internal combustion engine 1 according to the invention for several cylinders, comprising a cylinder housing 2 and a cylinder head 3. Reference numeral s denotes a cylinder head sealing plane between the cylinder housing 2 and the cylinder head 3. Several cylinders 4 are arranged in the cylinder housing 2 – for example, a cylinder block or a crankcase. A cylinder liner 5 is arranged in each cylinder 4 and is surrounded by a cooling jacket 6 located in the cylinder housing 2.

[0033] In each cylinder liner 5, a piston 7 is arranged, reciprocating in the direction of the cylinder axis 4a of the cylinder 4 between a bottom dead center (BDC) and a top dead center (TDC). The top dead center (TDC) of the piston corresponds to an upper first end 8 of the cylinder 4, and the bottom dead center (BDC) of the piston 7 corresponds to a lower second end 9 of the cylinder 4. Each piston 7 is connected via a connecting rod 10 to a crankshaft 11, the crankshaft axis of which is designated 11a.

[0034] A piston cooling device 12 is provided for cooling the piston 7. The cooling device 12 has one channel ring section 13 per cylinder 4, which is embedded between a formed stop 14 and a cylinder liner 5. An upper first end face 18 faces the piston 7 and a lower second end face 19 faces the crankshaft 11. The stop 14 is formed, for example, by an annular shoulder in the region of the second end 9 of the cylinder 4. The diameter d of the annular shoulder is smaller than the outer diameter D of the channel ring section 13 (Fig. 2). In the illustrated embodiments, the stop 14 is formed by the cylinder housing 2. Alternatively, according to an embodiment of the invention not shown, the stop 14 can be formed by a separate component that is rigidly connected to the cylinder housing 2.

[0035] The channel ring section 13 is inserted into the cylinder 4 from the side of the first end 8 – i.e., from the side of the cylinder head sealing plane s – in the direction of the cylinder axis 4a and pushed in until it reaches the stop 14. The second end face 19 of the channel ring section 13, facing the crankshaft 11 and away from the piston 7, rests directly against the stop 14. This largely prevents axial misalignment. The channel ring section 13 can be inserted loosely into the cylinder 4 – i.e., with radial play between the channel ring section 13 and the cylinder 4 – or it can be pressed into the cylinder 4.

[0036] The channel ring section 13 is inserted into the cylinder 4 in the direction of the cylinder axis 4a until it reaches the stop 14. The cylinder liner 5 is then inserted into the cylinder 4 from the side of the first end 8 until it reaches the channel ring section 13. The cylinder liner 5 can rest against the channel ring section 13, with the channel ring section 13 being clamped between the stop 14 and the cylinder liner 5. Alternatively, a defined clearance can be formed between the stop 14 and the cylinder liner 5 in the direction of the cylinder axis 4a. This allows for compensation of thermal expansion and prevents stresses in the channel ring section 13 and in the cylinder liner 5.

[0037] As can be seen from Fig. 2, each channel ring part 13 of the piston cooling device has

[0038] On the first end face 18, facing the piston 7 and thus away from the stop 14, at least one cooling nozzle 15 is provided, directed towards the underside 70 facing the crankshaft 11 or the inside of the piston 7. The spray pattern of the cooling nozzle 15 is designated by reference numeral 15a. Advantageously, at least one spray pattern 15a is inclined towards the cylinder axis 4a. Each cooling nozzle 15 originates from an annular, circumferential piston cooling channel 16 arranged in the channel ring part 13, which is, for example, formed into the channel ring part 13.

[0039] In the first embodiment shown in Fig. 2, each channel ring part has

[0040] 13 features a single circumferential piston cooling channel 16, which is fluidically connected to at least one cooling nozzle 15. In the exemplary embodiment, the cooling nozzle 15 is formed integrally with the channel ring part 13. According to an alternative embodiment (not shown), the cooling nozzle 15 can also be formed as a separate component and screwed or pressed into the channel ring part 13. At least two cooling nozzles 15 can have different spray geometries and / or different spray directions. This makes it possible to selectively cool hot spots of the piston 7.

[0041] In the illustrated embodiment, the piston cooling channel 16 is formed in the channel ring part 13 and is formed, for example, by a circumferential groove in the outer surface 130 of the channel ring part 13. Alternatively, in a variant embodiment of the invention not shown, the piston cooling channel 16 can also be formed in the cylinder housing 2 and, for example, by a circumferential groove in an inner surface of the cylinder 2. Furthermore, it is also possible to design the piston cooling channel 16 as a separate component that is rigidly connected to the cylinder housing 2 and / or the channel ring part 13.

[0042] The piston cooling channel 16 is connected to a pressurized oil supply 17 located in the cylinder housing 2. In one embodiment, the cooling nozzles 15 can be controlled and / or metered via at least one control element 17a.

[0043] Reference numeral 20 designates sealing devices between the channel ring part 13 and the cylinder housing 2 on both sides of the piston cooling channel 16. The sealing devices 20 can, for example, be formed by O-rings arranged in annular grooves of the channel ring part 13 and / or the cylinder housing 2.

[0044] The second embodiment shown in Fig. 3 differs from Fig. 2 in that the channel ring part 13 has two piston cooling channels 161, 162. A first piston cooling channel 161 and a second piston cooling channel 162 are arranged one above the other in the channel ring part 13, spaced apart in the direction of the cylinder axis 4a. Both the first piston cooling channel 161 and the second piston cooling channel 162 originate from the outer surface 130 of the channel ring part 13 and can each have a circumferential groove in the outer surface of the channel ring part 13 (see also Fig. 5).

[0045] A first cooling nozzle 151 or a first group of first cooling nozzles 151 extends from the first piston cooling channel 161. A second cooling nozzle 152 or a second group of second cooling nozzles 152 extends from the second piston cooling channel 162. This enables effective and demand-based cooling of the piston 7.

[0046] As can be seen from Fig. 3, the cooling nozzles 151, 152 can be incorporated into the channel ring part 13, i.e. integrated into it.

[0047] The first piston cooling channel 161 is fluid-connected to a first pressurized oil supply 171 located in the cylinder housing 2. The second piston cooling channel 162 is fluid-connected to a second pressurized oil supply 172 located in the cylinder housing 2.

[0048] The first pressure oil supply 171 and the second pressure oil supply 172 are switchable and / or meterable via control elements indicated by reference numerals 171a and 172a. This allows the first cooling nozzles 151 and the second cooling nozzles 152 to be controlled independently of each other. This makes it possible to increase or decrease the cooling of the piston 7 as required.

[0049] The first cooling nozzles 151 and the second cooling nozzles 152 can have different jet geometries and / or different jet directions.

[0050] The cooling ring part 13 can be designed as a casting. Alternatively or additionally, the cooling ring part 13 can be manufactured by additive and / or subtractive processes.

[0051] Fig. 4 shows a third embodiment, which differs from the embodiment shown in Fig. 3 essentially in that the position of the channel ring part 13 in the cylinder 4 is fixed by means of a positioning device 30.

[0052] The positioning device 30 enables simple and rapid installation of the channel ring part 13 with precise positioning. Furthermore, the positioning device 30 prevents unintentional rotation of the channel ring part 13 in the cylinder 4. In the illustrated embodiment, the positioning device 30 is formed by at least one positioning pin 31 engaging in a bore 32 of the channel ring part 13 and in a bore 33 of the cylinder housing 2 – approximately in the area of ​​the stop 14. Figures 5 and 6 show the arrangement of the positioning pin 31 in the second end face 19 of the channel ring part 13.

[0053] Alternatively, the positioning device 30 can also be formed by another positive-locking connection between the channel ring part 13 and the cylinder housing 2.

[0054] The cooling nozzles 151, 152 are formed in the embodiment shown in Figs. 4 to 6 by forming features on the channel ring part 13.

Claims

P A T E N T A N S P R Ü C H E 1. Internal combustion engine (1) with at least one cylinder (4) arranged in a cylinder housing (2), in which a piston (7) is arranged which moves back and forth in the direction of a cylinder axis (4a) of the cylinder (4) between a bottom dead center (BDC) and a top dead center (TDC), wherein a first end (8) of the cylinder (4) is assigned to the top dead center (TDC) and a second end (9) of the cylinder (4) is assigned to the bottom dead center (BDC), with a piston cooling device (12) which has at least one annular piston cooling channel (16) arranged in the region of the second end (9) of the cylinder (4) with at least one cooling nozzle (15) directed towards a bottom surface (70) of the piston (7);151, 152) characterized in that the annular piston cooling channel (16) is formed by a channel ring part (13) or is arranged in a channel ring part (13) which is inserted or pressed into the cylinder (4) - preferably from the side of the first end (8) of the cylinder (4) - in the direction of the cylinder axis (4a).

2. Internal combustion engine (1) according to claim 1, characterized in that at least one - preferably annular - stop (14) is arranged in the region of the second end (9) of the cylinder (4), wherein the channel ring part (13) in the cylinder (4) in the direction of the cylinder axis (4a) until it reaches the stop (14) is inserted.

3. Internal combustion engine (1) according to claim 1 or 2, characterized in that a cylinder liner (5) is arranged in the cylinder (4), which is inserted or pressed in from the side of the first end (8) in the direction of the cylinder axis (4a), wherein the cylinder liner (5) is inserted into the cylinder (4) in the direction of the cylinder axis (4a) up to the channel ring part (13).

4. Internal combustion engine (1) according to claim 3, characterized in that the cylinder liner (5) rests on the channel ring part (13), wherein preferably the channel ring part (13) is clamped between the stop (14) and the cylinder liner (5).

5. Internal combustion engine (1) according to claim 3, characterized in that a defined clearance in the direction of the cylinder axis (4a) is formed between the stop (14) and the cylinder liner (5).

6. Internal combustion engine (1) according to one of claims 1 to 5, characterized in that the channel ring part (13) has at least one circumferential piston cooling channel (16; 161, 162), wherein the piston cooling channel (16) is flow-connected to at least one cooling nozzle (15; 151, 152).

7. Internal combustion engine according to claim 6, characterized in that at least one piston cooling channel (16; 161, 162) is formed in the channel ring part (13), wherein preferably at least one piston cooling channel (16; 161, 162) is formed by a circumferential groove in the outer cylindrical surface (130) of the channel ring part (13).

8. Internal combustion engine (1) according to claim 6 or 7, characterized in that the channel ring part (13) has at least two piston cooling channels (161, 162), wherein preferably a first piston cooling channel (161) and a second piston cooling channel (162) are arranged spaced apart one above the other in the channel ring part (13) in the direction of the cylinder axis (4a).

9. Internal combustion engine (1) according to one of claims 6 to 8, characterized in that at least one piston cooling channel (16; 161, 162) extends from an outer surface (130) of the channel ring part (13).

10. Internal combustion engine (1) according to one of claims 6 to 9, characterized in that at least one cooling nozzle (15; 151, 152) is arranged in the region of a first end face (18) of the channel ring part (13) facing the piston (7) or in the channel ring part (13) between the piston cooling channel (16; 161, 162) and the first end face (18), wherein preferably the cooling nozzle (15; 151, 152) is formed in the channel ring part (13).

11. Internal combustion engine (1) according to one of claims 6 to 10, characterized in that the channel ring part (13) has a first cooling nozzle (151) or a first group of first cooling nozzles (151) and a second cooling nozzle (152) or a second group of second cooling nozzles (152), wherein the first cooling nozzle(s) (151) originate from the first piston cooling channel (161) and the second cooling nozzle(s) (152) originate from the second piston cooling channel (162).

12. Internal combustion engine (1) according to one of claims 6 to 11, characterized in that at least one piston cooling channel (16; 162, 162) is flow-connected to a pressure oil supply channel (17; 171, 172) arranged in the cylinder housing (2), wherein preferably the first piston cooling channel (161) is flow-connected to a first pressure oil supply channel (171) and the second piston cooling channel (162) is flow-connected to a second pressure oil supply channel (172).

13. Internal combustion engine (1) according to claim 12, characterized in that at least one pressure oil supply channel (17; 171, 172) is switchable and / or controllable, wherein preferably the first pressure oil supply channel (171) and the second pressurised oil supply channel (172) can be switched and / or controlled independently of each other.

14. Internal combustion engine (1) according to one of claims 1 to 13, characterized in that at least two cooling nozzles (15; 151, 152) have different jet geometries and / or different jet directions.

15. Internal combustion engine (1) according to one of claims 1 to 13, characterized in that at least one channel ring part (13) can be positioned by means of a positioning device (30) - preferably having a positioning pin (31).

16. Internal combustion engine (1) according to one of claims 1 to 15, characterized in that at least one cooling ring part (13) is formed by a casting or by an additively or subtractively manufactured part. 2025 10 28 FU / IV

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