Internal combustion engine with a first and a second coolant circuit

Abstract

Internal combustion engine (1) comprising a cylinder crankcase (2), a cylinder head (3), a first coolant circuit (4) and a second coolant circuit (5), wherein the cylinder crankcase (2) can be cooled by means of the first coolant circuit (4), wherein the cylinder head (3) can be cooled by means of the second coolant circuit (5), characterized in that the first coolant circuit (4) has a first coolant and the second coolant circuit (5) has a second coolant, wherein oil can be supplied to a main oil pressure gallery (12) by means of an oil pump (7) via an oil filter (8) and via an oil cooler (11), wherein the main oil pressure gallery (12) supplies the first coolant circuit (4), wherein a check valve (9) is arranged in a first bypass line (10) in parallel to the oil filter (8).

Description

[0001] The invention relates to an internal combustion engine having the features of the preamble of patent claim 1.

[0002] Various internal combustion engines with a cylinder crankcase and a cylinder head are known from the prior art, wherein the cylinder crankcase can be cooled with a first coolant circuit and the cylinder head with a second coolant circuit.

[0003] An internal combustion engine with a cooling system is known from DE 44 07 984 A1. The internal combustion engine has a cylinder crankcase in the form of a cylinder block and a cylinder head, with coolant flowing through the cylinder block and the cylinder head. The coolant is pumped and, after passing through the internal combustion engine, is led to a radiator. Two coolant circuits, each with separate channel systems, are provided. An upper channel system of a first coolant circuit, assigned to the combustion chambers of the cylinders, is formed in the cylinder block. A second channel system of a second coolant circuit, which can be separated from the first coolant circuit, is formed adjacent to the crankshaft drive. In the area around the combustion chambers of the cylinders, different temperature ranges develop at a relatively high temperature level.The different temperature ranges develop in the upper area of ​​the cylinder block, in the lower area of ​​the piston, and in the area of ​​the combustion chamber floors of the cylinder head. These different, closely spaced temperature ranges lead to undesirable thermal expansion of the materials located there and to the resulting stresses that are absorbed by a cylinder head gasket. The cooling system is intended to achieve a balanced temperature level around the combustion chambers in order to reduce thermal stresses in this area and to enable targeted airflow to areas at risk from heat near the cylinder head floor plate. The lower channel system is limited at the top by a partition wall. The upper channel system is located above the partition wall. This upper channel system extends around the areas of both the cylinder head and the cylinder block close to the combustion chamber.It is connected to the lower duct system located below the partition wall by a connecting line. A thermostatic valve is located in the connecting line, which closes the connecting line as long as the coolant in the lower duct system has not reached a temperature close to the engine's optimal operating temperature. The upper duct system drains via a main thermostatic valve to a radiator, and from there to the pump. The lower duct system drains into the upper duct system via the connecting line.

[0004] DE 103 06 695 A1 discloses an internal combustion engine with two coolant circuits. Both coolant circuits are fed by a coolant pump. The coolant flow generated by the coolant pump is divided between a first cooling line of the first coolant circuit and a second cooling line of the second coolant circuit. The division takes place at the crankcase. The cooling lines can be integrated into the crankcase or designed as separate components. The first cooling line is connected to the cylinder crankcase, namely to a cooling jacket of the cylinder crankcase. An actuator is provided in this first coolant circuit, which is assigned to the first cooling line. The coolant supply to the first cooling line is controlled or regulated via the actuator as a function of the coolant temperature. The actuator is designed, in particular, as a thermostat.The second cooling line leads to a cooling channel in the cylinder head. The second cooling line and thus the cooling channel are constantly supplied with coolant, while the cooling of the crankcase by the first coolant circuit is activated as needed by means of appropriate control or position of the actuator. The coolant flow of the second coolant circuit forms a main coolant flow. An additional cooling channel is provided in the cylinder head in the immediate vicinity of the valves and is connected to the second cooling line. The second cooling line is assigned at least one transition to the cylinder head, via which the second cooling line is connected to the additional cooling channel. The transition can be designed as an opening in the cylinder head gasket. At least two exhaust valves are provided per cylinder, with the additional cooling channel being arranged in the cylinder head between the exhaust valves.The additional cooling channel cools the area between the exhaust ports, an injector shaft and a cylinder base.

[0005] An internal combustion engine is known from the generic DE 100 47 080 A1. The internal combustion engine has a cylinder block and a cylinder head. A cooling system has two separate coolant circuits for the cylinder crankcase and the cylinder head. The two coolant circuits are fed by a common coolant pump, with the coolant pump initially conveying the coolant into a distributor rail. The coolant flows via the distributor rail via at least one channel into the coolant chamber of the cylinder crankcase and into the coolant chamber of the cylinder head. The distributor rail is arranged along one long side of the cylinder crankcase. The coolant flows from the distributor rail into a distributor channel and then into a coolant jacket in the area of ​​the cylinder liners.After the coolant has passed all the cylinder liners, it enters a transition channel and from there into an outlet channel in the cylinder head. The effective flow cross-section between the transition channel and the outlet channel is determined by the geometric contour of an opening in the cylinder head gasket. The opening in the cylinder head gasket has a geometric contour such that the coolant from the distributor rail is distributed with a volume fraction of 50% to 20% to the coolant jacket of the cylinder crankcase and with a volume fraction of 50% to 80% to the coolant chamber of the cylinder head. The cylinder head gasket also has through-openings for the coolant, which are operatively connected to channels to the coolant chamber of the cylinder head. There are two through-openings per cylinder.This makes it possible to achieve different coolant flow rates in the cylinder head and cylinder crankcase by using different cylinder head gaskets when using the same basic body for the cylinder crankcase and cylinder head. This makes it possible to achieve different coolant temperatures in the cylinder crankcase and the cylinder head. The different coolant temperatures are achieved by regulating the respective coolant flow rates. The coolant flow can be controlled using two differently designed thermostatic valves. This means that the cylinder crankcase can be operated at a coolant temperature that is approximately 20° to 30° Celsius higher than the cylinder head. This should result in better oil viscosity, lower wall heat loss and reduced piston friction in the cylinder crankcase, while in the cylinder head the aim is to achieve better cooling of the exhaust valve areas, which are particularly susceptible to heat.

[0006] From the document GB 2 498 782 A, an internal combustion engine with a cylinder crankcase, with a cylinder head, with a first coolant circuit and with a second coolant circuit is known, wherein the cylinder crankcase can be cooled by means of the first coolant circuit, wherein the cylinder head can be cooled by means of the second coolant circuit. GB 2 498 782 A shows that the first coolant circuit has a first coolant (oil) and the second coolant circuit has a second coolant (water). Regions of the cylinder crankcase adjacent to the cylinder head between the pistons of the internal combustion engine can also be cooled by means of the second coolant. GB 2 498 782 A also discloses a piston cooling nozzle connected to the first coolant circuit, by means of which the first coolant can be sprayed onto the associated piston.

[0007] DE 10 2013 214 865 A1 discloses an internal combustion engine with an oil circuit and a water circuit. The internal combustion engine comprises a cylinder head and a cylinder block. The cylinder block, which serves as the upper crankcase half, is equipped with an integrated coolant jacket to provide oil cooling. The coolant jacket integrated in the cylinder block can be supplied with oil, which originates from the oil pan and serves as coolant, via a first supply line using a pump. A filter is arranged downstream of the pump. The cylinder head of the internal combustion engine is also liquid-cooled and equipped with an integrated coolant jacket, which is supplied with coolant, i.e. water, on the inlet side via a supply line. A pump for pumping the water is arranged in the supply line on the inlet side.

[0008] DE 10 2010 044 026 A1 discloses a hybrid cooling system for an internal combustion engine, which has at least two cooling circuits, of which a block cooling circuit is carried by engine oil, and a head cooling circuit is carried by a liquid cooling medium, e.g., a water-glycol mixture, and both cooling circuits have a common heat exchanger. The head cooling circuit has a pump, a head cooling jacket, a cabin heat exchanger, a shut-off valve, a thermostat, and a main cooler. A sensor for recording the coolant temperature is arranged in the head cooling circuit. Another temperature sensor is arranged on the outlet side of the cylinder block to record the oil temperature. An oil filter is also arranged in the block cooling circuit. At the beginning of a warm-up phase, the shut-off valve of the head cooling circuit is closed, thus preventing the flow of liquid cooling medium, e.g.,of the water-glycol mixture, prevented by the heat exchanger.

[0009] DE 600 05 872 T2 discloses a cylinder head and a block of an internal combustion engine of a motor vehicle. A cooling system of the engine includes a first circuit for cooling the head and a second circuit for cooling the block, which are completely separate from each other and utilize a first fluid and a second fluid, respectively. A bypass line is provided, controlled by a flow control valve, such as a proportional solenoid valve, whereby a portion of the oil coming from a heat exchanger flows directly back into an oil pan.

[0010] The prior art therefore includes internal combustion engines with separate coolant circuits for the cylinder crankcase and the cylinder head. These generic internal combustion engines are not yet optimally designed. The cooling power requirement is lower in the cylinder crankcase than in the cylinder head. The prior art attempted to meet the different cooling power requirements by using different cooling circuits. The disadvantage of the prior art is that, despite the different coolant circuits, the cooling power cannot be optimally adapted to the demand.

[0011] The invention is therefore based on the object of designing and developing the internal combustion engine mentioned at the outset in such a way that an improved adaptation to the cooling power requirements of the cylinder crankcase and the cylinder head can be achieved.

[0012] This object underlying the invention is now achieved by an internal combustion engine having the features of patent claim 1. The first coolant circuit has a first coolant and the second coolant circuit has a second coolant. The two coolants are different. The two independent coolants can control the temperature of the cylinder crankcase and the cylinder head almost independently. The material separation of the two coolant circuits decouples the cooling of the cylinder crankcase and the cylinder head. It is particularly advantageous if the two coolants have different thermal coefficients. The invention has the further advantage that the cylinder crankcase can be heated quickly during warm-up. This minimizes friction losses and can reduce CO2 emissions.

[0013] The two coolants can, for example, be water and oil. The first coolant is oil, with the cylinder crankcase being cooled or coolable with the oil. The second coolant is preferably water, with the cylinder head being coolable with the water. The oil volume can be increased by additional oil cooling of the cylinder crankcase. The engine pressure oil replaces cooling water. The cylinder head and the remaining components to be cooled are preferably water-cooled. A reduction in thermal mass is possible due to the lower thermal coefficient of oil compared to water.

[0014] In particular, the first coolant can be supplied to the first cooling circuit under pressure. In particular, engine oil can be supplied to the coolant circuit. The pressurized oil-based design of the first coolant circuit can also be implemented in existing engine concepts with foreseeable effort. A separate coolant pump is assigned to each of the two coolant circuits. The first coolant circuit can preferably be supplied with pressurized oil by an oil pump. The second coolant circuit can preferably be supplied with water by a water pump.

[0015] In an alternative embodiment, it is conceivable that the first coolant circuit is formed by a pressureless circulating oil cooling system. The cooling jacket of the cylinder crankcase can be used as a dry sump reservoir.

[0016] In a particularly preferred embodiment, a higher temperature level is provided in the cylinder crankcase, in particular more than 110° Celsius. This minimizes friction losses. Reducing friction losses can also lead to a reduction in CO2 emissions. The cylinder head can be cooled. This can increase fatigue strength.

[0017] The cylinder crankcase has web regions formed between the pistons, wherein the web regions are coupled to the second coolant circuit assigned to the cylinder head and can thus be cooled. The regions of the cylinder liners facing the web regions are thus effectively cooled. The cooling channels are connected, in particular, via supply lines, for example, via bores, to the coolant chambers in the cylinder head. The web regions are cooled, in particular, with water. The web regions have cooling channels, preferably in the form of bores, wherein the bores are supplied with the second coolant. Designing the cooling channels as bores is easy to manufacture. The cooling channels can be formed by two V-shaped, interconnected bores in the web regions. Alternatively, the cooling channels can be designed as slots. The slots extend transversely between the pistons in the longitudinal direction of the web regions.Through the slots, the coolant is in extensive contact with the web areas. Alternatively, the cooling channels can be formed as cast-in channels in the web areas.

[0018] A temperature sensor for measuring the coolant temperature of the first coolant is arranged in the first coolant circuit. The temperature of the oil flowing through the cooling jacket is measured, in particular, by the temperature sensor. The temperature sensor can be arranged, in particular, at an outlet of the cooling jacket. A proportional valve, in particular, is arranged downstream of the outlet. Depending on the measured coolant temperature, the coolant flow through the first coolant circuit is regulated and / or controlled by means of the proportional valve. The coolant supply of the first coolant, in particular the corresponding oil supply, is regulated and / or controlled by the proportional valve. The proportional valve is arranged in a return line downstream of a cooling jacket.The oil from the cylinder crankcase, in particular from the cooling jacket of the cylinder crankcase, can be returned to the oil pan without pressure via the return line on the cylinder crankcase downstream of the proportional valve.

[0019] According to the invention, oil is supplied to a main oil pressure gallery via an oil filter and an oil cooler by means of an oil pump, the main oil pressure gallery feeding the first coolant circuit, and a check valve being arranged in a first bypass line parallel to the oil filter. The oil circulating in the cooling jacket is preferably fed by a main oil pressure gallery. The main oil pressure gallery is fed with pressurized oil by means of the oil pump and via a downstream oil filter and a downstream oil cooler. The oil cooler can preferably be bypassed by a temperature-controlled bypass line, in particular by means of a corresponding thermostat or a corresponding valve, so that the oil is fed directly into the main oil pressure gallery during a cold start.

[0020] The main oil pressure gallery supplies at least one, in particular several, piston cooling nozzles with pressurized oil, preferably via a switching valve. The piston cooling nozzles are provided for cooling the pistons, and the piston cooling nozzles are supplied with oil from the main oil pressure gallery via a line and a switching valve.

[0021] The disadvantages mentioned above are therefore avoided and corresponding advantages are achieved.

[0022] There are now numerous possibilities for advantageously designing and developing the aforementioned internal combustion engine. For this purpose, reference is first made to the claims subordinate to claim 1. A preferred embodiment of the invention is explained in more detail below with reference to the drawings and the associated description.

[0023] The drawing shows: Fig. 1 in a highly schematic, partially sectioned representation of an internal combustion engine with a cylinder crankcase and a cylinder head, and Fig. 2 shows a highly schematic plan view of the cylinder crankcase.

[0024] In Fig. 1 clearly shows an internal combustion engine 1 with a cylinder crankcase 2 and a cylinder head 3. The internal combustion engine 1 is designed particularly for use in a motor vehicle. The cylinder head 3 and the cylinder crankcase 2 are connected to each other, in particular via a screw connection (not shown).

[0025] The internal combustion engine 1 now has a first coolant circuit 4 and a second coolant circuit 5. The cylinder crankcase 2 can be cooled by means of the first coolant circuit 4. The cylinder head 3 can be cooled by means of the second coolant circuit 5.

[0026] The disadvantages mentioned above are now avoided by the fact that the first coolant circuit 4 has a first coolant and the second coolant circuit 5 has a second coolant. This has the advantage that the cylinder head 3 and the cylinder crankcase 2 can be temperature-controlled essentially independently of one another. The cylinder head 3 can be temperature-controlled in particular to a temperature range below 100° Celsius, in particular less than 90° Celsius, in particular approximately 70° Celsius. The cylinder crankcase 2 can be temperature-controlled to a temperature range of more than 100° Celsius, preferably to a temperature range of more than 110° Celsius, in particular approximately 120° Celsius.

[0027] The two coolants are made of different materials. According to the invention, the first coolant is an oil, with the cylinder crankcase 2 being cooled with the oil. The second coolant is preferably water, with the cylinder head 3 being cooled with the water. Additives such as an antifreeze and / or corrosion inhibitor can be mixed into the water.

[0028] In the following, the first coolant circuit 4 will be discussed in more detail. Fig.1 also schematically shows an oil pan 6. The oil collected in the oil pan 6 is pumped by an oil pump 7 via a corresponding line (not designated in more detail) to an oil filter 8. According to the invention, a check valve 9 is arranged in a first bypass line 10 parallel to the oil filter 8. The bypass line 10 bypasses the oil filter 8. Downstream of the bypass line 10 and the oil filter 8, an oil cooler 11 is arranged in the first coolant circuit 4. The oil emerging from the oil cooler 11 is fed to a main oil pressure gallery 12. Due to the pressure losses at the oil cooler 11 and the oil filter 8, the oil pressure provided in the main oil pressure gallery 12 is lower than the pump outlet pressure of the oil pump 7. A further bypass line 13 is arranged parallel to the oil cooler 11 and bypasses the oil cooler 11. The bypass line 13 flows into the main oil pressure gallery 12. The bypass line 13 can now be switched by means of a valve 14.The valve 14 can in particular be designed as a thermostat.

[0029] The main oil pressure gallery 12 now supplies oil to a cooling jacket 15. The cooling jacket 15 is part of the cylinder crankcase 2. When the oil is directed through the cooling jacket 15, the cylinder liners (not shown in detail) are cooled.

[0030] The cylinder crankcase 2 has the web regions 17, wherein the web regions 17 are formed between the cylinders or pistons 16. The web regions 17 in the cylinder crankcase 2 are now preferably connected to the second coolant circuit 5 via cooling channels 18. The web regions 17 are therefore water-cooled. This has the advantage that the web regions 17 can be cooled to a low temperature level. Because the web regions 17 are also water-cooled, they can be cooled to a cooler temperature together with the cylinder head 3. This makes it possible to increase the fatigue strength of the internal combustion engine 1.

[0031] A temperature sensor 19 is preferably assigned to the first coolant circuit 4. The temperature sensor 19 can, for example, be arranged at an outlet 20 of the cooling jacket 15. The temperature sensor 19 measures the temperature of the first coolant, namely the corresponding oil. The outlet 20 opens into a return line 21. A valve, in particular in the form of a proportional valve 22, is arranged in the return line 21. The coolant circuit 4 can be regulated and controlled by means of the proportional valve 22. The flow through the cooling jacket 15 can be controlled, in particular, by partially opening and closing the proportional valve 22. Downstream of the proportional valve 22 and downstream of the return line 21, the first coolant, namely the corresponding oil, flows back into the oil pan 6 without pressure.

[0032] The main oil pressure gallery 12 preferably also supplies at least one piston cooling nozzle 23, wherein appropriate oil can be sprayed onto the piston 16, in particular onto the piston crown of the piston 16, by means of the piston cooling nozzle 23. For this purpose, a line 24 is provided from the main oil pressure gallery 12 to the piston cooling nozzle 23. A switching valve 25 is arranged in the line 24. In the embodiment shown here, engine pressure oil is used, which is branched off from the main oil pressure gallery 12 to feed the coolant circuit 5. In an alternative embodiment, the coolant circuit 5 of the cylinder crankcase 2 can be designed to be pressureless, wherein this coolant circuit 5 is used as part of the corresponding oil reservoir.

[0033] The oil from the cylinder crankcase 2, namely from the corresponding cooling jacket 15, can be drained by opening the proportional valve 22, whereby the oil is thus replaced during a regular oil change. LIST OF REFERENCE SYMBOLS 1 internal combustion engine 2 cylinder crankcases 3 cylinder head 4 Coolant circuit 5 Coolant circuit 6 Oil pan 7 Oil pump 8 oil filters 9 Check valve 10 Bypass line 11 Oil cooler 12 Main Oil Print Gallery 13 Bypass line 14 Valve 15 Cooling jacket 16 pistons 17 Bridge area 18 Cooling channel 19 Temperature sensor 20 Outlet 21 Return line 22 Proportional valve 23 Piston cooling nozzle 24 line 25 switching valve

Claims

[1] Internal combustion engine (1) with a cylinder crankcase (2), with a cylinder head (3), with a first coolant circuit (4) and with a second coolant circuit (5), wherein the cylinder crankcase (2) can be cooled by means of the first coolant circuit (4), wherein the cylinder head (3) can be cooled by means of the second coolant circuit (5), characterized by in that the first coolant circuit (4) has a first coolant and the second coolant circuit (5) has a second coolant, wherein oil can be supplied to a main oil pressure gallery (12) by means of an oil pump (7) via an oil filter (8) and via an oil cooler (11), wherein the main oil pressure gallery (12) feeds the first coolant circuit (4), wherein a check valve (9) is arranged in a first bypass line (10) parallel to the oil filter (8). [2] Internal combustion engine according to claim 1, characterized by that the second coolant is water, wherein the cylinder head (3) can be cooled with the water. [3] Internal combustion engine according to claim 1 or 2, characterized by that the cylinder crankcase (2) has web regions (17) formed between pistons (16), wherein the web regions (17) have cooling channels (18), wherein the cooling channels (18) are coupled to the second coolant circuit (5). [4] Internal combustion engine according to claim 3, characterized by that the cooling channels (18) are designed as bores. [5] Internal combustion engine according to one of the preceding claims, characterized by that a temperature sensor (19) for measuring the coolant temperature of the first coolant is arranged in the first coolant circuit (4), wherein the coolant flow through the first coolant circuit (4) can be regulated and / or controlled by means of a proportional valve (22) as a function of the coolant temperature. [6] Internal combustion engine according to claim 5, characterized bythat the proportional valve (22) is arranged in a return line (21) downstream of a cooling jacket (15). [7] Internal combustion engine according to the preceding claim, characterized by that the oil cooler (11) can be bridged by means of a temperature-controlled valve (14) with a bypass line (13), wherein during a cold start the oil can be fed into the main oil pressure gallery (12) via the bypass line (13). [8] Internal combustion engine according to one of the preceding claims, characterized by that at least one piston cooling nozzle (23) is provided for cooling the pistons (16), wherein the at least one piston cooling nozzle (23) is fed with oil from the main oil pressure gallery (12) via a line (24) and via a switching valve (25).

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