internal combustion engine

Abstract

Internal combustion engine, with at least one cylinder (12) and with a crankshaft (14) to which at least one connecting rod (1) is attached, wherein each connecting rod (1) has a bearing eye (3) for connecting it to the crankshaft (14) and a connecting rod bearing eye (2), wherein the main bearings (16) of the crankshaft (14) can be supplied with hydraulic oil via a main bearing gallery (20) by means of a first hydraulic oil circuit (15) having at least one first oil pump (17, 18), wherein at least one first oil pump (17, 18) is arranged to draw hydraulic oil from an oil reservoir (19), wherein, starting from the main bearing gallery (20), a partial flow of hydraulic oil can be supplied to each main bearing (16) of the crankshaft (14) for lubrication. wherein the lifting bearing eye (3) of the or each connecting rod (1) can be supplied with hydraulic oil via the crankshaft (14) by means of a second hydraulic oil circuit (24) having at least one second oil pump (25), characterized by the fact that the second hydraulic oil circuit (24) is independent of the first hydraulic oil circuit (15), the second oil pump (25) being designed to also draw hydraulic oil from the oil reservoir (19), The first hydraulic oil circuit (15) and the second hydraulic oil circuit (24) are coupled downstream of the second oil pump (25) of the second hydraulic oil circuit (24) and downstream of a switching valve (26) of the second hydraulic oil circuit (24) via a check valve (27), wherein the check valve (27) allows oil flow from the second hydraulic oil circuit (24) into the first hydraulic oil circuit (15), but prevents reverse oil flow from the first hydraulic oil circuit (15) towards the second hydraulic oil circuit (24).

Description

[0001] The invention relates to an internal combustion engine, in particular an internal combustion engine with a variable compression ratio.

[0002] In internal combustion engines, a high compression ratio has a positive effect on efficiency. The compression ratio is the ratio of the total cylinder volume before compression to the remaining cylinder volume after compression. In spark-ignition internal combustion engines, such as gasoline engines, which generally have a fixed compression ratio, the compression ratio must be chosen to be high enough to prevent knocking under full load. However, for the far more frequent partial load range of the internal combustion engine, i.e., with low cylinder filling, a higher compression ratio could be chosen without causing knocking. The important partial load range of an internal combustion engine can be improved if the compression ratio is variably adjustable.

[0003] From DE 10 2010 016 037 A1, an internal combustion engine with an adjustable compression ratio is known. Connecting rods, which have a crankshaft bearing eye and a connecting rod bearing eye, can be connected to a crankshaft via the crankshaft bearing eye and to a respective cylinder piston of the internal combustion engine via the connecting rod bearing eye. Each connecting rod is associated with an eccentric adjusting device comprising an eccentric body and eccentric rods. The eccentric body has a piston pin bore arranged eccentrically to a center point of the connecting rod bearing eye, with the piston pin bore accommodating a piston pin.

[0004] The eccentric adjustment device serves to adjust the effective connecting rod length leff, where the connecting rod length is defined as the distance from the center of the piston pin bore to the center of the crankpin eye. To rotate the eccentric body and thus change the effective connecting rod length leff, the eccentric rods of the adjustment device are movable. Each eccentric rod is associated with a piston, which is slidably mounted or guided in a hydraulic chamber. Hydraulic pressure is present in the hydraulic chambers, acting on the pistons associated with the eccentric rods. Depending on the amount of oil in the hydraulic chambers, the movement of the eccentric rods may or may not be possible.

[0005] The adjustment of the eccentric adjustment device of a variable-compression internal combustion engine is initiated by the inertial and load forces of the engine, which act on the eccentric adjustment device during a power stroke. During a power stroke, the directions of the forces acting on the eccentric adjustment device constantly change. The adjustment movement of the eccentric adjustment device is assisted by hydraulically lubricated pistons that act on the eccentric rods. The pistons prevent the eccentric adjustment device from retracting due to the varying directions of the forces acting on it. The eccentric rods, which interact with the pistons, are connected to the eccentric body on both sides.The hydraulic chambers, in which the pistons are guided, can be supplied with hydraulic oil via hydraulic oil supply lines and filled from the lifting bearing eye.

[0006] Check valves on each connecting rod prevent hydraulic oil from flowing back from the hydraulic chambers into the hydraulic oil supply lines. A changeover valve is housed in a bore of each connecting rod. The hydraulic chambers are connected to the bore containing the changeover valve via hydraulic oil drain lines. The switching position of the changeover valve determines which of the hydraulic chambers is filled with hydraulic oil and which is emptied, thereby affecting the direction of adjustment or rotation of the eccentric adjustment mechanism.The hydraulic oil, which acts on the pistons of the eccentric rods guided in the hydraulic chambers, is supplied to the hydraulic chambers from the connecting rod bearing eye of the respective connecting rod via the hydraulic oil supply lines. The connecting rod engages the crankshaft with its connecting rod bearing eye in such a way that a connecting rod bearing shell is positioned between the crankshaft (specifically, a crankshaft bearing journal) and the connecting rod bearing eye. The hydraulic oil is supplied via the crankshaft and flows through the connecting rod bearing shell and the connecting rod bearing eye into the hydraulic oil supply lines. The hydraulic chambers can be vented via the hydraulic oil drain lines, depending on the switching position of the changeover valve. This determines the direction of adjustment or rotation of the eccentric adjustment mechanism.

[0007] DE 10 2012 019 176 A1 discloses another internal combustion engine with a variable compression ratio. In this design, the crankshaft for variable adjustment of the compression ratio is arranged in a frame pivotally mounted in the crankcase of the internal combustion engine, the frame including a lubricating oil supply for the crankshaft.

[0008] DE 102 07 750 B4 discloses details of a hydraulic system for an internal combustion engine used to effect a change in connecting rod length in conjunction with an engine lubrication system. The hydraulic system comprises several oil pumps, a sump, a filter, a check valve, and a control valve.

[0009] From US Patent 5,501,190 A, an internal combustion engine is known, wherein first pumps supply bearings in the area of ​​the crankshaft with hydraulic oil, wherein second pumps supply cylinders with hydraulic oil, and wherein a third pump supplies an intake manifold with hydraulic oil.

[0010] The subsequently published DE 10 2015 120 905 A1 discloses an internal combustion engine according to the preamble of claim 1.

[0011] US 6 497 203 B1, DE 691 08 572 T2 and US 5 247 914 A disclose further prior art.

[0012] The object of the invention is to create an internal combustion engine with an improved hydraulic oil supply. This object is achieved by an internal combustion engine according to claim 1.

[0013] In the internal combustion engine according to the invention, the first hydraulic oil circuit supplies hydraulic oil to the main bearings of the crankshaft. The second hydraulic oil circuit supplies hydraulic oil to the crankshaft-side connecting rod bearing eye of the connecting rod(s). The hydraulic oil circuits have separate, independent oil pumps, with the oil pumps of both independent hydraulic oil circuits drawing hydraulic oil from a common oil reservoir. The two independent hydraulic oil circuits therefore do not branch off from each other and draw oil from the oil reservoir.

[0014] The hydraulic oil supply to the crankshaft-side connecting rod bearing journals is functionally separate from the hydraulic oil supply to the crankshaft's main bearings. The hydraulic oil supply to the main crankshaft bearings via the first hydraulic circuit is tailored to the needs of the main bearings, while the hydraulic oil supply to the crankshaft-side connecting rod bearing journals via the respective second hydraulic circuit is tailored to the needs of the connecting rods, and in the case of an internal combustion engine with a variable compression ratio, particularly to the needs of eccentric adjustment devices. This ensures, for example, that at low engine speeds, when the first oil pump of the first hydraulic circuit is not operating, the respective second hydraulic circuit provides optimal pressure for the connecting rod bearing journals.

[0015] According to the invention, the first hydraulic oil circuit and the second hydraulic oil circuit are coupled to each other downstream of the second oil pump of the second hydraulic oil circuit and downstream of a switching valve of the second hydraulic oil circuit via a check valve, wherein the check valve allows an oil flow from the second hydraulic oil circuit into the first hydraulic oil circuit, but prevents a reverse oil flow from the first hydraulic oil circuit towards the second hydraulic oil circuit.

[0016] According to a first alternative of the invention, in addition to the main bearings of the crankshaft, at least one cylinder head, including camshaft bearings and / or camshaft adjusters of the respective cylinder head, can be supplied with hydraulic oil via the first oil pump of the first hydraulic oil circuit. Camshaft bearings and / or camshaft adjusters can thus be supplied with hydraulic oil as required. In this case, with the exception of the connecting rods, preferably also the remaining engine assemblies can be supplied with hydraulic oil via the first oil pump of the first hydraulic oil circuit. These remaining engine assemblies include a timing drive for driving the respective camshaft and / or a chain tensioner and / or, in the case of turbocharged engines, at least one turbocharger.

[0017] According to a second alternative of the invention, in addition to the connecting rod bearing eye of the connecting rod(s), at least one cylinder head, including camshaft bearings and / or camshaft adjusters of the camshaft(s) mounted in the respective cylinder head, can be supplied with hydraulic oil via the second oil pump of the second hydraulic oil circuit. In this second alternative of the invention, the camshaft bearings and / or the camshaft adjusters can also be supplied with hydraulic oil in a manner specifically adapted to the requirements. In this case, the remaining engine assemblies can be supplied with hydraulic oil via the first oil pump of the first hydraulic oil circuit. These remaining engine assemblies include a timing drive for driving the camshaft(s) mounted in the respective cylinder head and / or a chain tensioner and / or, in the case of turbocharged engines, at least one turbocharger.

[0018] According to a third alternative of the invention, at least one cylinder head can be supplied with hydraulic oil via the first or each first oil pump of the first hydraulic oil circuit and via the second or each second oil pump of the second hydraulic oil circuit, such that a first group of camshaft bearings of the or each camshaft mounted in the respective cylinder head can be supplied with hydraulic oil via the first hydraulic oil circuit, and that a second group of camshaft bearings and camshaft adjusters of the or each camshaft mounted in the respective cylinder head can be supplied with hydraulic oil via the second hydraulic oil circuit. The second group of camshaft bearings includes the or each highly stressed camshaft bearing in the area of ​​a timing drive of the engine. In the third alternative of the invention, the camshaft bearings and / or the camshaft adjusters can also be supplied with hydraulic oil in a manner specifically adapted to the requirements.The remaining engine components can in turn be supplied with hydraulic oil via the first oil pump of the first hydraulic oil circuit, whereby these remaining engine components include a timing drive for driving the camshaft or camshaft mounted in the respective cylinder head and / or a chain tensioner and / or, in the case of turbocharged engines, at least one turbocharger.

[0019] Preferably, in all of the above alternatives, a timing drive for driving the camshaft(s) mounted in the respective cylinder head can be supplied with hydraulic oil via the first oil pump(s) of the first hydraulic oil circuit. Supplying the timing drive with hydraulic oil via the first hydraulic oil circuit is particularly advantageous.

[0020] In all the above alternatives, the second hydraulic oil circuit downstream of the second oil pump comprises the switching valve and, downstream of the switching valve, preferably a pressure sensor. When the pressure sensor of the second hydraulic oil circuit measures an oil pressure in the second hydraulic oil circuit that is less than a limit value, the switching valve assumes a first switching position in which the oil pumped by the second oil pump of the second hydraulic oil circuit can be supplied to the second hydraulic oil circuit. Conversely, when the pressure sensor of the second hydraulic oil circuit measures an oil pressure in the second hydraulic oil circuit that is greater than a limit value, the switching valve assumes a second switching position in which the oil pumped by the second oil pump can be supplied to the first hydraulic oil circuit via a check valve connected between the second hydraulic oil circuit and the first hydraulic oil circuit downstream of the switching valve.which prevents oil flow from the first hydraulic circuit to the second hydraulic circuit, but allows flow from the second hydraulic circuit to the first. Should the oil pump of the second hydraulic circuit deliver too much hydraulic oil, this excess can be fed back into the first hydraulic circuit via the check valve. The delivery volume of the oil pump(s) of the first hydraulic circuit can then be adjusted accordingly. Any excess oil delivered by the oil pump of the second hydraulic circuit can easily be fed back into the first hydraulic circuit.

[0021] Although the invention can be used in both constant-compression and variable-compression internal combustion engines, its use in variable-compression internal combustion engines is particularly preferred. In a variable-compression internal combustion engine, the second hydraulic oil circuit supplies hydraulic oil to the connecting rod bearing eyes and, from the connecting rod bearing eyes, at least to the connecting rod eccentric adjustment devices.

[0022] Preferred embodiments of the invention are described in the dependent claims and the following description. Exemplary embodiments of the invention are explained in more detail with reference to the drawing, without being limited thereto. The drawing shows: Fig. 1 a hydraulic oil diagram of a first internal combustion engine according to the invention; Fig. 2 a hydraulic oil diagram of a second internal combustion engine according to the invention; Fig. 3 a hydraulic oil diagram of a third internal combustion engine according to the invention; Fig. 4 a connecting rod of an internal combustion engine with a variable compression ratio.

[0023] Fig. Figure 4 shows a connecting rod 1 of an internal combustion engine with a variably adjustable compression ratio. The connecting rod 1 has a connecting rod body 7 with a connecting rod bearing eye 2 and a crank bearing eye 3.

[0024] The connecting rod bearing eye 2 serves to connect the respective connecting rod 1 to a cylinder piston (not shown) of a respective cylinder 12 of the internal combustion engine.

[0025] The connecting rod bearing eye 3 serves to connect the respective connecting rod 1 to a crankshaft 14 (see Fig. 1, Fig. 2, Fig. 3) of the internal combustion engine.

[0026] The connecting rod 1 of the Fig. 4 has an eccentric adjusting device 6 arranged at least partially in the connecting rod bearing eye 2, preferably hydraulically adjustable.

[0027] The eccentric adjusting device 6 has a piston pin bore arranged eccentrically to a central axis 8 of the connecting rod bearing eye 2, with a central axis which receives a piston pin (not visible). The respective connecting rod 1 is coupled to the cylinder piston of the respective cylinder 12 via the piston pin.

[0028] The eccentric adjusting device 6 serves to adjust the effective connecting rod length leff of the connecting rod 1. A rotation of the adjustable eccentric adjusting device 6 is initiated by the action of mass and load forces of the internal combustion engine, which act on the eccentric device 6 during a power stroke of the internal combustion engine. During a power stroke, the directions of action of the forces acting on the eccentric device 6 change continuously.

[0029] The rotary or adjusting movement is supported by pistons integrated in the connecting rod 1 and guided in hydraulic chambers, which are supplied with hydraulic oil, in particular engine oil, or the pistons prevent the eccentric adjusting device 6 from resetting due to varying directions of force acting on the eccentric adjusting device 6.

[0030] The pistons of the eccentric adjusting device 6 are operatively connected on both sides to an eccentric body 9 of the eccentric adjusting device 6 by means of eccentric rods 4, 5. The eccentric adjusting device 6 can comprise the pistons, the eccentric rods 4, 5 and the eccentric body 9. The pistons of the eccentric adjusting device 6 are connected via in Fig. 4 non-visible hydraulic oil lines from the lifting bearing eye 3 with hydraulic oil via into Fig. Four non-visible check valves are actuated. The check valves prevent the hydraulic oil from flowing back from the piston volumes of the pistons into the hydraulic oil lines in the engine compartment of the internal combustion engine.

[0031] A switching valve 10 is accommodated in a bore of the respective connecting rod 1.

[0032] The hydraulic chambers of the eccentric adjusting device 6 of the respective connecting rod 1 are in contact with the bore accommodating the switching valve 10 via hydraulic oil lines. The switching position of the switching valve 10 determines which of the hydraulic chambers is filled with hydraulic oil and which of the hydraulic chambers is emptied, whereby the adjustment direction or rotation direction of the eccentric adjusting device 6 depends on this.

[0033] The respective switching valve 10 of the respective connecting rod 1 has a gripper 11. The respective switching valve 10 can be actuated via the gripper 11, namely by means of an actuating device 11 acting on the gripper 11. Details of the switching valve 10 of the respective connecting rod 1 and the gripper 11 of the respective switching valve 10 are familiar to the person skilled in the art, for example, from DE 10 2012 112 461 A1.

[0034] The invention presented here relates to such details of the internal combustion engine with a preferably variable compression ratio that ensure a reliable hydraulic oil supply to the crankshaft 14 and, furthermore, a reliable supply of hydraulic oil or engine oil to the connecting rods 1, in particular to the eccentric adjusting devices 6 of the connecting rods 1.

[0035] Although the invention is described below for an internal combustion engine with a variable compression ratio, the invention can also be used in an internal combustion engine with a constant compression ratio.

[0036] The internal combustion engine has a first hydraulic oil circuit 15, which serves to supply the main bearings 16 of the crankshaft 14 with hydraulic oil or with engine oil for lubrication.

[0037] Thus, this first hydraulic oil circuit 15 has at least one first oil pump, in the illustrated embodiments the first oil pumps 17 and 18, via which hydraulic oil or engine oil can be drawn from an oil reservoir 19, wherein this oil drawn by the oil pumps 17, 18 of the first hydraulic oil circuit 15 can be supplied to the main bearings 16 of the crankshaft 14 via a so-called main bearing gallery 20.

[0038] Starting from the main bearing gallery 20, each main bearing 16 of the crankshaft 14 is connected according to Fig. 1, Fig. 2 and Fig. 3. A partial flow of hydraulic oil or engine oil can be supplied to lubricate the respective main bearing point 16 of the crankshaft 14. In the case of the Fig. 1, Fig. 2, Fig. The main bearing 16 of the crankshaft 14 shown on the far right is the so-called support bearing of the crankshaft 14.

[0039] According to Fig. 1, Fig. 2, Fig. 3 is preferably integrated into the first hydraulic oil circuit 15 a heat exchanger 21, in particular designed as an oil water heat exchanger, for temperature control of the hydraulic oil or engine oil, and an oil filter 22 for cleaning the hydraulic oil or engine oil.

[0040] Furthermore, it shows Fig. 1, Fig. 2, Fig. 3. A pressure sensor 23 of the first hydraulic oil circuit 15, with the aid of which the oil pressure prevailing in the first hydraulic oil circuit 15 can be measured in order to adjust the delivery rate of the oil pump 17 of the first hydraulic oil circuit 15 accordingly. The oil pump 17 of the first hydraulic oil circuit 15, whose delivery rate is adjustable, is connected in parallel to the oil pump 18 of the first hydraulic oil circuit 15, whose delivery rate is not adjustable.

[0041] The internal combustion engine comprises hydraulic oil for supplying at least the connecting rod bearing eyes 3 and, in the case of an internal combustion engine with a variable compression ratio, also for supplying at least the eccentric adjusting devices 6 of the connecting rods 1. Fig. 1, Fig. 2, Fig. 3 further a second hydraulic oil circuit 24. This second hydraulic oil circuit 24 is an independent or self-contained hydraulic oil circuit from the first hydraulic oil circuit 15 and has at least one second oil pump 25, in the illustrated embodiments a single second oil pump 25, which also draws hydraulic oil from the oil reservoir 19.

[0042] Via this second hydraulic oil circuit 24, the crankshaft-side lifting bearing eyes 3 of the connecting rods and, in the case of an internal combustion engine with a variable compression ratio, also the eccentric adjusting devices 6 of the connecting rods 1 can be supplied with hydraulic oil, namely engine oil.

[0043] Via this second hydraulic oil circuit 24, the hydraulic oil, which serves to supply the connecting rods 1, can be supplied via a central oil feed 29 into the crankshaft 14 and via oil lines integrated into the crankshaft 14 to the lifting bearing eyes 3 and via the lifting bearing eyes 3 to the eccentric adjusting devices 6 of the connecting rods 1.

[0044] The supply of hydraulic oil to the crankshaft-side bearing eyes 3 of the connecting rods 1 and, in the case of an internal combustion engine with a variable compression ratio, additionally to the supply of the eccentric adjusting devices 6 of the connecting rods 1, is therefore functionally separate from the supply of hydraulic oil to the main bearings 16 of the crankshaft 14.

[0045] According to the invention, the first hydraulic oil circuit 15 and the second hydraulic oil circuit 24 are coupled to each other downstream of the oil pump 25 of the second hydraulic oil circuit 24 and downstream of a switching valve 26 of the second hydraulic oil circuit 24 via a check valve 27. The check valve 27 allows oil flow from the second hydraulic oil circuit 24 into the first hydraulic oil circuit 15, but prevents reverse oil flow from the first hydraulic oil circuit 15 towards the second hydraulic oil circuit 24.

[0046] The oil pump 25 of the second hydraulic oil circuit 24 is preferably an oil pump with a variably adjustable delivery volume.

[0047] The second hydraulic oil circuit 24, like the first hydraulic oil circuit 15, has a pressure sensor 28. The pressure sensor 28, which is positioned downstream of the switching valve 26, measures the hydraulic oil pressure in the second hydraulic oil circuit 24 immediately upstream of the central oil supply 29. When the hydraulic oil pressure measured by the pressure sensor 28 in the second hydraulic oil circuit 24 is less than a limit value, the switching valve 26 of the second hydraulic oil circuit 24 opens. Fig. 1, Fig. 2, Fig. The first switching position shown in Figure 3 is entered, in which the hydraulic oil supplied by the oil pump 25 of the second hydraulic oil circuit 24 is fed to the connecting rod bearing eyes 3. Then, however, if the hydraulic oil pressure in the second hydraulic oil circuit 24, as detected by the pressure sensor 28, is greater than a limit value, the switching valve 26 assumes a second switching position, in which the hydraulic oil supplied by the oil pump 25 of the second hydraulic oil circuit 24 can then be fed to the first hydraulic oil circuit 15 via the check valve 27.

[0048] If the hydraulic oil pump 25 of the second hydraulic oil circuit 24 delivers too much hydraulic oil, this excess hydraulic oil can be fed to the first hydraulic oil circuit 15 and thus to the main bearing gallery 20 via the check valve 27, preferably with adjustment of the delivery volume of the oil pump 18 of the first hydraulic oil circuit 15.

[0049] The supply of hydraulic oil to the main bearings 16 of the crankshaft 14 and the connecting rod bearing eyes 3 is functionally separate. The main bearings 16 of the crankshaft 14 are supplied with hydraulic oil or engine oil via the first hydraulic oil circuit 15 and the main bearing gallery 20. The connecting rod bearing eyes 3 are supplied with hydraulic oil or engine oil via their own hydraulic oil circuit 24 with their own oil pump 25, whereby the second hydraulic oil circuit 24 is coupled to the first hydraulic oil circuit 15 downstream of the oil pump 25 via the check valve 27. Fig. 1, Fig. 2, Fig. Figure 3 further shows an oil filter 36 in the second hydraulic oil circuit 24 as well as the return of hydraulic oil from the main bearings 16 of the crankshaft 14 and the connecting rods 1 towards the oil reservoir 19.

[0050] In the exemplary embodiment of the Fig. 1. Each cylinder head 13, including camshaft bearings, shift tappets or roller rocker arms and / or camshaft adjusters (all not shown), and each camshaft (not shown) mounted in the respective cylinder head 13, can be supplied with hydraulic oil via the first hydraulic oil circuit 15. A hydraulic oil line 30 leading to the respective cylinder head 13 branches off from the main bearing gallery 20. Fig. Figure 1 further shows the return of hydraulic oil from the cylinder heads 13 towards the oil reservoir 19 via return lines 31, pumps 32 and air-oil separator 33.

[0051] In the exemplary embodiment of the Fig. 1, except for the connecting rods 1 or the crank bearing eye 3 of the or each connecting rod 1, the remaining assemblies of the engine can be supplied with hydraulic oil via the or each first oil pump 17, 18 of the first hydraulic oil circuit 15, wherein these remaining assemblies of the engine include in particular a timing drive for driving the or each camshaft mounted in the respective cylinder head 13 and / or a chain tensioner and / or, in the case of turbocharged engines, at least one turbocharger.

[0052] In the exemplary embodiment of the Fig. 2. The at least one cylinder head 13, including camshaft bearings, switching tappets or roller rocker arms and / or camshaft adjusters (all not shown), of the camshaft (not shown) mounted in the respective cylinder head 13, can be supplied with hydraulic oil via the second hydraulic oil circuit 24. A hydraulic oil line 30 leading to the respective cylinder head 13 branches off from the second hydraulic oil circuit 24, namely downstream of the switching valve 26 and the pressure sensor 28 and upstream of the central oil supply 29. Fig. Figure 2 further shows the return of hydraulic oil from the cylinder heads 13 towards the oil reservoir 19 via return lines 31, pumps 32 and air-oil separator 33.

[0053] In the exemplary embodiment of the Fig. 2. The remaining engine assemblies can be supplied with hydraulic oil via the first oil pump 17, 18 of the first hydraulic oil circuit 15, wherein these remaining engine assemblies include in particular a timing drive for driving the camshaft or each camshaft and / or a chain tensioner and / or, in the case of turbocharged engines, at least one turbocharger.

[0054] In the exemplary embodiment of the Fig. 3 The respective cylinder head 13 can be supplied with hydraulic oil via both the first hydraulic oil circuit 15 and the second hydraulic oil circuit 24, namely in such a way that a first group of camshaft bearings of the or each camshaft 34 mounted in the respective cylinder head 13 as well as shift tappets or roller rocker arms can be supplied with hydraulic oil via the or each first oil pump 17, 18 of the first hydraulic oil circuit 15, and that a second group of camshaft bearings and camshaft adjusters 35 of the or each camshaft 34 mounted in the respective cylinder head 13 can be supplied with hydraulic oil via the or each second oil pump 25 of the second hydraulic oil circuit 24.

[0055] A first hydraulic oil line 30a leading to the respective cylinder head 13 branches off from the main bearing gallery 20, a second hydraulic oil line 30b leading to the respective cylinder head 13 branches off from the second hydraulic oil circuit 24 upstream of the central oil supply 29 into the crankshaft 14.

[0056] The second group of camshaft bearings preferably comprises the or each highly loaded camshaft bearing, in particular exclusively the first camshaft bearing immediately adjacent to the timing drive. The first group of camshaft bearings preferably comprises the second to fourth camshaft bearings.

[0057] In the exemplary embodiment of the Fig. 3. The remaining engine assemblies are in turn supplied with hydraulic oil via the first oil pump 17, 18 of the first hydraulic oil circuit 15, wherein these remaining engine assemblies include a timing drive for driving the camshaft or each camshaft mounted in the respective cylinder head 13 and / or a chain tensioner and / or, in the case of turbocharged engines, at least one turbocharger.

[0058] Fig. Figure 3 shows the return of hydraulic oil from the cylinder heads 13 towards the oil reservoir 19 via return lines 31, pumps 32 and air-oil separator 33.

[0059] In all embodiments, a control drive for driving the camshaft 34 mounted in the respective cylinder head 13 can be supplied with hydraulic oil via the first oil pump 17, 18 of the first hydraulic oil circuit 15.

[0060] The invention was granted with reference to Fig. 1, Fig. 2, Fig. 3 and Fig. 4 is described for an internal combustion engine with a variable compression ratio. The invention can also be used in an internal combustion engine with a constant compression ratio. In this case, the second hydraulic oil circuit 24 then serves in particular to supply the connecting rod bearing eyes 3 of the connecting rods 1 with hydraulic oil.

[0061] The terms hydraulic oil circuit and hydraulic oil can also be used interchangeably with engine oil circuit and engine oil. The hydraulic oil pumped in the first hydraulic oil circuit 15 and in the second hydraulic oil circuit 24 is therefore engine oil. The two hydraulic oil circuits allow for a demand-based oil supply to the respective assemblies or oil consumers, thereby reducing the overall oil flow rate. Furthermore, the bearing width of the bearings can be optimized.

Claims

[1] Internal combustion engine, with at least one cylinder (12) and with a crankshaft (14) to which at least one connecting rod (1) is attached, wherein each connecting rod (1) has a bearing eye (3) for connecting it to the crankshaft (14) and a connecting rod bearing eye (2), wherein the main bearings (16) of the crankshaft (14) can be supplied with hydraulic oil via a main bearing gallery (20) by means of a first hydraulic oil circuit (15) having at least one first oil pump (17, 18), wherein at least one first oil pump (17, 18) is arranged to draw hydraulic oil from an oil reservoir (19), wherein, starting from the main bearing gallery (20), a partial flow of hydraulic oil can be supplied to each main bearing (16) of the crankshaft (14) for lubrication. wherein the lifting bearing eye (3) of the or each connecting rod (1) can be supplied with hydraulic oil via the crankshaft (14) by means of a second hydraulic oil circuit (24) having at least one second oil pump (25), characterized by , that the second hydraulic oil circuit (24) is independent of the first hydraulic oil circuit (15), the second oil pump (25) being designed to also draw hydraulic oil from the oil reservoir (19), The first hydraulic oil circuit (15) and the second hydraulic oil circuit (24) are coupled downstream of the second oil pump (25) of the second hydraulic oil circuit (24) and downstream of a switching valve (26) of the second hydraulic oil circuit (24) via a check valve (27), wherein the check valve (27) allows oil flow from the second hydraulic oil circuit (24) into the first hydraulic oil circuit (15), but prevents reverse oil flow from the first hydraulic oil circuit (15) towards the second hydraulic oil circuit (24). [2] Internal combustion engine according to claim 1, characterized by , that at least one cylinder head (13) including camshaft bearings and / or camshaft adjusters of the or each camshaft mounted in the respective cylinder head (13) can be supplied with hydraulic oil via the first hydraulic oil circuit (15). [3] Internal combustion engine according to claim 2, characterized by, that a hydraulic oil line (30) leading to the respective cylinder head (13) branches off from the main bearing gallery (20). [4] Internal combustion engine according to claim 1, characterized by , that at least one cylinder head (13) including camshaft bearings and / or camshaft adjusters of the or each camshaft mounted in the respective cylinder head (13) can be supplied with hydraulic oil via the second hydraulic oil circuit (24). [5] Internal combustion engine according to claim 4, characterized by , that a hydraulic oil line leading to the respective cylinder head (13) branches off upstream of a central oil supply (29) into the crankshaft (14) from the second hydraulic oil circuit (24). [6] Internal combustion engine according to claim 1, characterized by, that at least one cylinder head (13) can be supplied with hydraulic oil via both the first hydraulic oil circuit (15) and the second hydraulic oil circuit (24), namely in such a way that a first group of camshaft bearings of the or each camshaft (34) mounted in the respective cylinder head (13) can be supplied with hydraulic oil via the first hydraulic oil circuit (15), and that a second group of camshaft bearings and camshaft adjusters (35) of the or each camshaft (34) mounted in the respective cylinder head (13) can be supplied with hydraulic oil via the second hydraulic oil circuit (24). [7] Internal combustion engine according to claim 4, characterized by, that a first hydraulic oil line (30a) leading to the respective cylinder head (13) branches off from the main bearing gallery (20), and that a second hydraulic oil line (30b) leading to the respective cylinder head (13) branches off from the second hydraulic oil circuit (24) upstream of a central oil feed (29) into the crankshaft (14). [8] Internal combustion engine according to any one of claims 2 to 7, characterized by , that a control drive for driving the or each camshaft mounted in the respective cylinder head (13) can be supplied with hydraulic oil via the first hydraulic oil circuit (15). [9] Internal combustion engine according to any one of claims 1 to 8, characterized by, that the same has connecting rods (1) with an eccentric adjusting device (6) for adjusting an effective connecting rod length in order to provide a variably adjustable compression ratio, wherein the eccentric adjusting device (6) of the respective connecting rod (1) has an eccentric body (9) and eccentric rods acting on the eccentric body (9) which are subjected to a hydraulic pressure prevailing in hydraulic chambers cooperating with the eccentric rods, and wherein the eccentric adjusting device (6) of the respective connecting rod (1) can be supplied with hydraulic oil via the second hydraulic oil circuit (24). [10] Internal combustion engine according to any one of claims 1 to 9, characterized bythat the second hydraulic oil circuit (24) downstream of the second oil pump (25) comprises the switching valve (26) and downstream of the switching valve (26) a pressure sensor (28), wherein when the pressure sensor (28) of the second hydraulic oil circuit (24) measures an oil pressure in the second hydraulic oil circuit that is less than a limit value, the switching valve (26) assumes a first switching position in which the oil pumped by the second oil pump (25) of the second hydraulic oil circuit (24) can be supplied to the second hydraulic oil circuit (24), whereas when the pressure sensor (28) of the second hydraulic oil circuit (24) measures an oil pressure in the second hydraulic oil circuit that is greater than a limit value, the switching valve (26) assumes a second switching position in which the oil pumped by the second oil pump (25) can be supplied to the first hydraulic oil circuit (15),namely via the check valve (27) connected between the second hydraulic oil circuit (24) and the first hydraulic oil circuit (15) downstream of the switching valve (26).

Images