Gas exchange valve control system for an internal combustion engine and internal combustion engine

Abstract

Gas exchange valve actuation system (10) for an internal combustion engine, in particular for a large internal combustion engine, with at least one camshaft (11) which carries intake cams (12) for actuating the intake valves and exhaust cams (13) for actuating the exhaust valves for a cylinder group of adjacent cylinders, wherein in a first embodiment the intake cams (12) and in a second embodiment the exhaust cams (13) are arranged non-rotatably on the respective camshaft (11) and can be driven by the respective camshaft (11), and wherein in the first embodiment the exhaust cams (13) and in the second embodiment the intake cams (12) are rotatably mounted on the respective camshaft (11) and can be driven by a separate drive shaft (14), wherein in the first embodiment each exhaust cam (13) and in the second embodiment each intake cam (12) is connected to a gear via an individual gear (15, 17). (16,18) of the respective drive shaft (14) is engaged, or in the first variant, two exhaust cams (13) and in the second variant, two intake cams (12) are engaged via a common gear (15, 17) with a gear (16, 18) of the respective drive shaft (14).

Description

The invention relates to a gas exchange valve control system for an internal combustion engine and an internal combustion engine. Large internal combustion engines are used, for example, as marine engines on ships. In large internal combustion engines, the cylinders have piston diameters of at least 140 mm, and in particular at least 175 mm. An internal combustion engine has multiple cylinders. Each cylinder of the internal combustion engine has at least one intake valve and at least one exhaust valve. Combustion air can be drawn into the respective cylinder through the intake valve, and exhaust gases can be expelled from the respective cylinder through the exhaust valve. In addition to the gas exchange valves, the cylinders of an internal combustion engine have fuel metering devices through which fuel can be introduced into each cylinder. To control the gas exchange valves of the cylinders of an internal combustion engine, the engine has a gas exchange valve control system. Such a gas exchange valve control system has at least one camshaft. From DE 10 2009 012 144 A1 and DE 195 81 459 T5, a concentric camshaft with two cam sections is known. Internal combustion engines are known in which intake cams for actuating the intake valves and exhaust cams for actuating the exhaust valves of cylinders are arranged on separate camshafts. Furthermore, gas exchange valve actuation systems for internal combustion engines are known in which the intake cams for actuating the intake valves and the exhaust cams for actuating the exhaust valves of cylinders are arranged on at least one common camshaft. Camshafts that carry both intake and exhaust cams are also referred to as mixed camshafts. Gas exchange valves with camshafts, on which both intake cams for actuating the intake valves and exhaust cams for actuating the exhaust valves are arranged, do not yet allow independent, flexible adjustment of the valve timing for the intake and exhaust valves of the internal combustion engine cylinders. This currently requires the intake and exhaust cams to be arranged on separate camshafts. There is a need for a gas exchange valve actuation system for an internal combustion engine in which the intake and exhaust cams can be arranged together on at least one camshaft, but which nevertheless enables independent, flexible valve timing for the intake and exhaust valves of the internal combustion engine cylinders. Based on this, the invention aims to create a novel gas exchange valve control system for an internal combustion engine and an internal combustion engine with such a gas exchange valve control system. This objective is achieved by a gas exchange valve control system according to claim 1 and an internal combustion engine according to claim 9. In a first embodiment of the invention, the intake cams, and in a second embodiment, the exhaust cams, are arranged non-rotatably on the respective camshaft and can be driven from the respective camshaft. In the first embodiment of the invention, the exhaust cams, and in the second embodiment, the intake cams, are rotatably mounted on the respective camshaft and can be driven from a separate drive shaft. In the gas exchange valve actuation system according to the invention, in the first embodiment only the intake cams, and in the second embodiment only the exhaust cams, are arranged non-rotatably on the respective camshaft, whereas in the first embodiment the exhaust cams, and in the second embodiment the intake cams, are rotatably mounted on the respective camshaft and can be driven from the respective separate drive shaft.This makes it possible to provide independent, flexible valve timing for the intake and exhaust valves of the internal combustion engine cylinders, even with minimal installation space requirements and despite the arrangement of the intake and exhaust cams on a common camshaft. In particular, existing internal combustion engines can be easily retrofitted or converted using the gas exchange valve control system according to the invention. According to the invention, in the first embodiment of the invention, each exhaust cam and in the second embodiment of the invention, each intake cam, engages with a gear on the respective drive shaft via an individual gear. Alternatively, in the first embodiment of the invention, two exhaust cams and in the second embodiment of the invention, two intake cams engage with a gear on the respective drive shaft via a common gear. When, in the first embodiment of the invention, each exhaust cam and in the second embodiment of the invention, each intake cam engages with a gear on the drive shaft via an individual gear, the remaining engine architecture can remain unchanged compared to an internal combustion engine with mixed camshafts on which the intake and exhaust cams are arranged in a rotationally fixed manner, in particular the design and arrangement of tappets and rocker arms.However, if in the first variant of the invention two exhaust cams and in the second variant of the invention two intake cams are operatively connected to a gear of the drive shaft via a common gear, the design and arrangement of the tappets and rocker arms must be adapted. Preferably, the respective camshaft and the respective separate drive shaft are meshed via drive gears, namely via a camshaft drive gear arranged on the respective camshaft and via a drive shaft drive gear arranged on the respective drive shaft. This allows the respective drive shaft to be driven from the respective camshaft. Preferably, each camshaft is assigned a phase adjuster to rotate it relative to the camshaft drive gear. Alternatively or additionally, each drive shaft is assigned a phase adjuster to rotate it relative to the drive shaft drive gear. The respective phase adjuster allows the camshaft drive gear to be rotated relative to the camshaft and the drive shaft drive gear relative to the drive shaft, thus providing correspondingly flexible valve timing for the intake and / or exhaust valves. Preferably, fuel cams, which serve to control fuel pumps, are arranged on the respective camshaft in a rotationally fixed manner and can be driven from the respective camshaft. The fuel delivered by the fuel pumps can be individually introduced into the respective cylinder via electronically or electrically controlled fuel metering devices. This allows for a particularly compact design of an internal combustion engine. Preferred embodiments of the invention are set forth in the dependent claims and the following description. Exemplary embodiments of the invention are explained in more detail with reference to the drawings, without being limited thereto. Figure 1 shows a schematic section of a camshaft of a first internal combustion engine according to the invention, Figure 2 a schematic section of a camshaft of a second internal combustion engine according to the invention, Figure 3 a schematic section of a camshaft of a third internal combustion engine according to the invention, Figure 4 a further schematic section of the camshaft of Figure 1, Figure 2 or Figure 3, and Figure 5 an alternative to Figure 4. Fig. 1 shows a section of a first gas exchange valve actuation system 10 according to the invention for an internal combustion engine, in particular for a large internal combustion engine, wherein Fig. 1 shows a camshaft 11 on which both intake cams 12 for actuating intake valves and exhaust cams 13 for actuating exhaust valves of a group of cylinders arranged side by side in a row are arranged. In Fig. 1, the exhaust cams 13 are arranged on the camshaft 11 in a rotationally fixed manner, in particular by means of an interference fit. The intake cams 12, on the other hand, are arranged rotatably on the camshaft 11 in Fig. 1. The intake cams 12, which are rotatably arranged on the camshaft 11, can be driven from a separate drive shaft 14. The drive shaft 14 runs parallel to the camshaft 11, with each intake cam 12 being operatively connected to a gear 15 to drive the intake cams 12, which are rotatably mounted on the camshaft 11. This gear 15 meshes with a gear 16 located on the separate drive shaft 14. A rotational movement of the drive shaft 14 is thus transmitted to the respective intake cam 12 via the meshing gears 15 and 16. Fig. 2 shows a modification of the gas exchange valve control system 10 of Fig. 1, in which the intake cams 12 are fixedly mounted on the camshaft 11 and the exhaust cams 13 are rotatably mounted on the camshaft 11. Accordingly, in Fig. 2, gears 17 are operatively connected to the exhaust cams 13, which mesh with gears 18 arranged on the separate drive shaft 14 in order to transmit a rotary motion of the separate drive shaft 14 to the exhaust cams 13 via the meshing gears 17, 18. In the embodiments shown in Figures 1 and 2, the rotatably mounted cams on the respective camshaft 11—intake cams 12 in Figure 1 and exhaust cams 13 in Figure 2—are individually operatively connected to a gear 15 or 17 rotatably mounted on the camshaft 11. These gears, 15 and 17 respectively, engage with a gear 16 or 18 on the respective separate drive shaft 14 via the gears 15 and 17, which are rotatably mounted on the respective camshaft 11. This engagement drives the meshing gears 15, 16 or 17, 18 from the drive shaft 14, thus driving the respective cams—intake cam 12 in Figure 1 and exhaust cam 13 in Figure 2. The gears 16 and 18 are fixed against rotation on the drive shaft 14. Fig. 3 shows a further modification of a gas exchange valve control system 10 according to the invention, in which, as shown in Fig. 3, two intake cams 15 rotatably arranged on the camshaft 11 are each assigned a common gear 15, also rotatably mounted on the camshaft 11, in order to mesh via this common gear 15 with a gear 16 fixedly arranged on the separate drive shaft 14. This allows the number of gears 15, 16 to be reduced, namely halved, compared to Fig. 1. The principle of Fig. 3 can also be transferred to Fig. 2 in order to drive two rotatably mounted exhaust cams 13 via a common gear 17, which meshes with a gear 18 arranged on the drive shaft 14. The camshaft 11 is driven, as shown in Fig. 4, by a camshaft drive gear 19 arranged on the camshaft 11, and the separate drive shaft 14 by a drive shaft gear 20 arranged on the same shaft, which mesh together in Fig. 4. The camshaft drive gear 19 can be driven from a crankshaft to drive the camshaft 11. The separate drive shaft 14 can then also be driven from the camshaft 11 via the meshing drive gears 19 and 20. As shown in Fig. 4, a phase adjuster 21 is assigned to the camshaft 11 and / or a phase adjuster 22 to the separate drive shaft 14. The phase adjuster 21 allows the camshaft 11 to be rotated relative to the camshaft drive gear 19, while the phase adjuster 22 allows the drive shaft 14 to be rotated relative to the drive shaft gear 20. This advantageously provides independent, flexible valve timing for the intake and exhaust valves. Fig. 5 shows a modification of Fig. 4, in which, in addition to the camshaft drive gear 19, a further camshaft drive gear 23 is provided, which ultimately serves to connect the camshaft 11 to the crankshaft. This can be advantageous for minimizing the installation space. In the illustrated embodiments, fuel cams 24 are arranged on the camshafts 11 in a rotationally fixed manner and can be driven via the respective camshaft 11. The fuel cams 24 serve to control fuel pumps, in particular high-pressure fuel pumps, to deliver fuel, wherein an electronically or electrically controlled fuel metering device, in particular a fuel injector, is coupled between the respective fuel pump and the respective cylinder, via which the fuel can ultimately be individually introduced into the respective cylinder. As already explained, in the gas exchange valve control system 10 according to the invention, either the intake cams 12 or the exhaust cams 13 arranged on the respective camshaft 11 are no longer fixedly mounted on the respective camshaft, but rather rotatably mounted to allow flexible valve timing for the intake and exhaust valves. The respective cams rotatably mounted on the respective camshaft 11 can be driven by a separate drive shaft 14. The camshaft 11 and the separate drive shaft 14 can each be phase-adjusted via phase adjusters 21, 22. The invention further relates to an internal combustion engine with a gas exchange valve control system 10, which is designed as described above. This system serves at least to control the gas exchange valves, i.e., the intake and exhaust valves, of cylinders arranged side by side in a row of the internal combustion engine, and in particular also to control fuel pumps. If the cylinders form several cylinder groups of adjacent cylinders, a gas exchange valve control system 10 preferably interacts with each cylinder group. The internal combustion engine according to the invention is in particular a large internal combustion engine, such as those used, for example, on ships. In large internal combustion engines, the cylinders have piston diameters of at least 140 mm, in particular at least 175 mm. Reference symbol list 10 Gas exchange valve control system 11 Camshaft 12 Intake cam 13 Exhaust cam 14 Drive shaft 15 Gear 16 Gear 17 Gear 18 Gear 19 Camshaft drive gear 20 Drive shaft drive gear 21 Phase adjuster 22 Phase adjuster 23 Camshaft drive gear 24 Fuel cam

Claims

Gas exchange valve actuation system (10) for an internal combustion engine, with at least one camshaft (11) which carries intake cams (12) for actuating the intake valves and exhaust cams (13) for actuating the exhaust valves for a cylinder group of adjacent cylinders, wherein in a first variant the intake cams (12) and in a second variant the exhaust cams (13) are arranged non-rotatably on the respective camshaft (11) and can be driven by the respective camshaft (11), and wherein in the first variant the exhaust cams (13) and in the second variant the intake cams (12) are rotatably mounted on the respective camshaft (11) and can be driven by a separate drive shaft (14), characterized in that in the first variant each exhaust cam (13) and in the second variant each intake cam (12) is connected via an individual gear (15, 17) to a gear (16,18) of the respective drive shaft (14) is engaged, or in the first variant, two exhaust cams (13) and in the second variant, two intake cams (12) are engaged via a common gear (15, 17) with a gear (16, 18) of the respective drive shaft (14). Gas exchange valve control system (10) according to claim 1, characterized in that the respective camshaft (11) and the respective separate drive shaft (14) run parallel to each other. Gas exchange valve control system (10) according to claim 1 or 2, characterized in that the respective camshaft (11) and the respective separate drive shaft (14) engage via drive gears (19, 20), namely via a camshaft drive gear (19) arranged on the respective camshaft (11) and via a drive shaft drive gear (20) arranged on the respective drive shaft (14). Gas exchange valve control system (10) according to claim 3, characterized in that a phase adjuster (21) is assigned to the respective camshaft (11) in order to rotate the respective camshaft (11) relative to the camshaft drive gear (19). Gas exchange valve control system (10) according to claim 3 or 4, characterized in that a phase adjuster (22) is assigned to the respective drive shaft (14) in order to rotate the respective drive shaft (14) relative to the drive shaft drive gear (20). Gas exchange valve control system (10) according to one of claims 1 to 5, characterized in that the respective camshaft (11) can be driven from a crankshaft and the respective drive shaft (14) can be driven from the respective camshaft (11). Gas exchange valve control system (10) according to one of claims 1 to 6, characterized in that fuel cams (24) for the control of fuel pumps are arranged in a rotationally fixed manner on the respective camshaft (11) and can be driven from the respective camshaft (11). Gas exchange valve control system (10) according to claim 7, characterized in that the fuel supplied by the fuel pumps can be individually introduced into the respective cylinder via electronically or electrically controllable fuel metering devices. Internal combustion engine, with several cylinders, wherein each cylinder has at least one inlet valve and at least one exhaust valve as gas exchange valves, in order to supply combustion air to each cylinder individually via the respective at least one inlet valve and to discharge exhaust gas from each cylinder individually via the respective at least one exhaust valve, wherein the cylinders form at least one cylinder group of cylinders arranged side by side, characterized in that a gas exchange valve control system (10) according to one of claims 1 to 8 is assigned to the cylinders of a respective cylinder group, which controls the inlet valves and exhaust valves of the cylinders of the respective cylinder group.

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