Cylinder-specific engine cooling

Abstract

Cooling system (1) of an internal combustion engine (2) with at least one cylinder (3a, 3b), comprising a first coolant line (81) with at least one device, which is in force-locking connection with the crankshaft of the internal combustion engine (34), for regulating the flow of a coolant (7, 9a, 9b, 15) and a spray device for applying a spray jet to the outer wall of a region of the internal combustion engine (10a, 10b), characterized in that the cooling system (1) is assigned to an internal combustion engine (2) which has at least a first (3a) and a second cylinder (3b) and at least a first directional control valve (9a) and a second directional control valve (9b), in which the first coolant line (8) branches at the first directional control valve (9a) into a first partial coolant line (81) leading to the second directional control valve (9b) and a second partial coolant line (82) leading to an expansion tank (11),and the first partial coolant line (8a) branches at the second directional control valve (9b) into a third partial coolant line (83) assigned to the first cylinder (3a) and a fourth partial coolant line (84) assigned to the second cylinder (3b).

Description

The invention relates to a cooling system for cooling selected sections of an internal combustion engine as a function of the crank angle, to a motor vehicle having the cooling system and to a method for cooling an internal combustion engine.Cooling of cylinder blocks and heads is conventionally made possible by a pressurized coolant, such as a water-glycol mix or oil. In this case, the coolant flows in a circulatory manner in channels and cavities provided for this purpose (the so-called water jacket). The requirements for cooling vary, inter alia, depending on the area of the internal combustion engine. Thus, different areas of a cylinder are subject to different thermal stresses in the individual cycles of the combustion cycle. Regions which are subject to particularly thermal stress are the outlet valve bridges, the intake and outlet ducts, the surge region in the region of the cylinder directed toward the cylinder head and the region of the cylinder head per se.The publication DE 10 2017 223 127 B3 discloses a cooling system of an internal combustion engine which is surrounded by a jacket, so that the outer wall of the internal combustion engine serves as an inner jacket wall. The cooling system includes refrigerant lines and a compressor as a means for controlling the flow of refrigerant. Coolant is introduced into the jacket by means of injection nozzles, the resulting spray jet reaching the outer wall of the internal combustion engine. In the publication DE 40 29 428 A1, an arrangement is disclosed in which a cooling oil pump is driven via the crankshaft of an internal combustion engine. The quantity of coolant flowing to individual cylinders of an internal combustion engine can be regulated by means of rotary valves (DE 10 2015 107 078 A1, DE 10 2015 009 568 A1). In the publication DE 100 59 687 A1, it is disclosed that internal combustion engines can be selectively cooled by oil at various points, wherein each cylinder is assigned a specific oil pump which is actuated by the crankshaft via cams.The publications DE 10 2013 205 244 A1 and DE 10 2016 113 620 A1 disclose additive methods for producing internal combustion engines. Heat pipes can be integrated into the corresponding component in order to allow cooling of thermally highly stressed regions.In addition to the cycle, the load of the internal combustion engine also has an influence on the thermal stress of certain regions. In this case, the cooling requirements are lower, for example in the warm-up phase of the operation of the internal combustion engine and with the cylinders deactivated than in full operation. Therefore, in the control of conventional cooling systems, balancing has to be made between requirements of material resistance, knocking behavior, friction and combustion chamber distortion. Providing unnecessary coolant flow requires a corresponding energy requirement and thus unnecessarily high fuel consumption.The object is to control the cooling of an internal combustion engine as a function of the thermal load.This object is achieved by a cooling system having the features of claim 1. Further advantageous embodiments and configurations of the invention are evident from the subordinate claims and the dependent claims, the figures and exemplary embodiments. The embodiments of the invention can be combined with one another in an advantageous manner.A first aspect of the invention relates to a cooling system of an internal combustion engine having at least one cylinder, comprising a first coolant line having at least one device which is connected in a force-fitting manner to the crankshaft of the internal combustion engine and is intended for regulating the flow of a coolant, and a spraying device for applying a spray jet to the outer wall of a region of the internal combustion engine.The cooling system according to the invention advantageously enables selective cooling of individual cylinders and / or selected regions of an internal combustion engine. As a result, it is possible to cool exactly those locations of an internal combustion engine at which the cooling is required. Furthermore, the frictional connection to the crankshaft advantageously enables cooling matched to the crank angle, so that cooling can be provided depending on the cycle for specific regions of an internal combustion engine in which a high level of heat generation takes place. In addition, the crankshaft-dependent control enables cooling at a very precise timing. The spraying of the coolant is advantageously effected in the form of a pulsating impact jet onto the outer wall, as a result of which a rapid dissipation of heat is made possible.As cooling agents, known in the prior art are used, e.g. water, a water-glycol mixture or an oil-based liquid, e.g. machine oil.Preferably, the means for controlling the flow of coolant is a coolant pump. The pump can be, for example, a piston pump or a centrifugal pump. The coolant pump can be actuated directly by the crankshaft, wherein the force-fit connection is produced by at least one cam arranged on the crankshaft.The crankshaft may also be mechanically connected to a separate camshaft driven by it. By controlling the pump, coolant is advantageously pumped into the coolant line when cooling is required.It is furthermore preferred if the means for regulating the flow of the coolant is a control valve. In this case, the control valve can advantageously control the flow of coolant at all and / or the flow of coolant into a specific coolant line depending on its design. Particularly preferably, the control valve is a directional control valve, for example a 3 / 2 directional control valve with three connections and two switching positions. The control of the coolant flow can also be provided both by a coolant pump and by a control valve, so that these two embodiments can be explicitly combined with one another. Particularly in the embodiment as a directional valve, the control valve is preferably controlled by a control device in order to set various switching positions. Further, the intensity of the flow of the coolant can be adjusted by the control device by varying the opening degree of the control valve.The cooling system according to the invention is associated with an internal combustion engine which has at least a first and a second cylinder and at least a first directional control valve and a second directional control valve, in which the first coolant line branches on the first directional control valve into a first partial coolant line leading to the second directional control valve and a partial coolant line leading to a compensation tank, the first partial coolant line branches on the second directional control valve into a third partial coolant line associated with the first cylinder and a fourth partial coolant line associated with the second cylinder. The internal combustion engine may have further cylinders, the cooling system having further control valves and corresponding further partial coolant lines assigned to the cylinders. As a result, the cylinders can advantageously be cooled separately. In a further preferred embodiment, the partial coolant lines are assigned to different regions of one or more cylinders.In a further preferred embodiment of the cooling system, the control valve is a distributor valve. A distributor valve is particularly advantageously suitable for cylinder-selective cooling. In this case, the distributor valve is actuated by cams of the crankshaft or a camshaft connected to the crankshaft in such a way that coolant is pumped from a pressurized coolant line in each case into the partial coolant line of a cylinder which is subject to thermal stress in accordance with the cycle sequence. A suitable distributor valve is, for example, a rotary valve. At the distributor valve, the coolant line branches into the partial coolant lines. As a result, more heat is advantageously dissipated from the cylinder by forced convection, for example during the combustion stroke, in which particularly much heat is produced. It is therefore particularly preferred if the cooling system is assigned to an internal combustion engine which has at least a first and a second cylinder and a pressurized fifth partial coolant line on the distributor valve branches into at least one partial coolant line which is sixth to the first cylinder and a seventh partial coolant line which is assigned to the second cylinder.The cooling system according to the invention is preferably assigned to an internal combustion engine which has been produced by an additive method. Additive methods, also referred to as three-dimensional printing methods, make it possible to produce thin-walled cylinder walls, which have grid structures, for example, in comparison with conventional internal combustion engines. The cooling system according to the invention is particularly suitable for these components because no cooling water jacket has to be provided. Furthermore, heat can be dissipated particularly effectively from the thin-walled structures by spraying coolant onto the outer wall.A second aspect of the invention relates to a motor vehicle having a cooling system according to the invention.A third aspect of the invention relates to a method for cooling an internal combustion engine with a cooling system according to the invention, wherein at least one valve and / or a coolant pump are actuated by cams of the crankshaft of the internal combustion engine or a camshaft connected to the crankshaft as a function of the crank angle and enable a flow of a coolant to a cooling region of the internal combustion engine. The advantages of the method correspond to the advantages of the cooling system according to the invention.The flow of the coolant is preferably controlled by a crank angle-dependent actuation of the valve. In this case, the flow of the coolant to a specific cylinder and / or to a specific region of the cylinder can advantageously be controlled. This embodiment is particularly suitable for the alternate cooling of different cylinders of a multi-cylinder internal combustion engine.Furthermore, it is preferred if the flow of the coolant is controlled by a crank angle-dependent actuation of the pump. In this case, the flow of the coolant to a specific cylinder and / or to a specific region of the cylinder can advantageously be controlled. In particular, this embodiment is suitable for alternately cooling different selected areas of a cylinder.The invention is explained in more detail with reference to the figures. They show FIG. 1 is a schematic illustration of an embodiment of a cooling system. FIG. 2 shows a schematic illustration of an embodiment of a cooling system. FIG. 3 shows a schematic illustration of an embodiment of the cooling system according to the invention. FIG. 4 shows a schematic illustration of an embodiment of the cooling system according to the invention.FIG. 1 shows an arrangement of a cooling system 1 with an internal combustion engine 2. The internal combustion engine 2 is a four-stroke spark-ignited internal combustion engine, it alternatively also being able to be self-igniting. The internal combustion engine 2 is manufactured by an additive method and has a thin-walled material having a solid structure, e.g., a grid structure, which meets the requirements. The internal combustion engine 2 is illustrated in FIG. 1 by way of example with a first cylinder 3 a. The cylinder 3a has a combustion chamber 31. A piston 32 is arranged in the combustion chamber 31, which is moved by the thermal expansion of hot gas produced during the combustion of injected fuel. The movement of the piston 32 is transmitted to a crankshaft 34 via a crank 33. For admitting a defined quantity of combustion air from an intake tract, not shown, into the cylinder 3 a, the inlet valve 4 is provided. Exhaust gases are discharged from the cylinder 3a via an exhaust tract, not shown. Exhaust valve 5 is provided for exhausting exhaust gas from cylinder 3a.The crankshaft 34 has a cam 6. During rotation of the crankshaft 34, a force-fit connection with a coolant pump 7 is produced via the cam 6. The coolant pump 7 is connected to a coolant reservoir, not shown, from which coolant is constantly provided for the coolant pump 7. The coolant pump 7 can also be connected to a conventional coolant circuit for the internal combustion engine 2 and further components of a corresponding motor vehicle. The coolant is, for example, water, water with glycol, or an oil-based liquid, for example machine oil.By the action of the cam movement, a certain volume of coolant is pumped from the coolant pump 7 via a first coolant line 8 to a first control valve 9 a. The first control valve 9a is designed as a 3 / 2-way valve. The control valve 9a accordingly has two switching positions. In the first switching position, the first control valve 9 ais connected to a first partial coolant line 81. The first partial coolant line 81 leads to a first injection device 10 a. The first spraying device 10 ais directed onto the outer wall of the first cylinder 3 ain the region of the inlet valve 4.In the second switching position, the first control valve 9 is connected to a second coolant line portion 82. The second partial coolant line 82 is connected to a compensating tank 11. For switching between the switching positions, the first control valve 9a has a magnetic coil. For controlling the switching, the first control valve 9 ais connected to a controller 12.In a method for cooling the first cylinder 3 a, the first control valve 9 ais switched to the first switching position in accordance with a control command from the control device 12. Coolant flows, when the coolant pump 7 is actuated, through the cam 6 of the crankshaft 34 to the first injection device 10 a, which sprays coolant onto the outer wall of the first cylinder 3 ain the region of the inlet valve 4. As a result of the evaporation of the coolant, heat is dissipated from the first cylinder 3 a.FIG. 2 shows a further embodiment of the cooling system 1. In contrast to the embodiment according to FIG. 1, the crankshaft 34 is connected to a camshaft 13. The camshaft 13 is driven by the crankshaft 34 so that it rotates synchronously with the crankshaft 34 and establishes a force-fit connection with a coolant pump 7 via a cam 14. The method for cooling functions correspondingly in the same way as described for FIG. 1.The number of cylinders of the internal combustion engine 2 can also be two, three, four or more. Each cylinder may be equipped with a cooling system 2. The cams 6, 14 can be designed in such a way that the coolant pumps of the individual cooling systems assigned to the cylinders are activated one after the other.A plurality of cylinders can also be supplied by the action of a coolant pump 7. In an embodiment according to the invention according to FIG. 3, a coolant pump 7 is used to supply coolant to the first spraying device 10 aof the first cylinder 3 aand to a second spraying device 10 bof a second cylinder 3 bin each case the same region in the vicinity of the respective inlet valve 4. The first control valve 9 ais connected via the first coolant line 81 to a second control valve 9 b, which is likewise designed as a 3 / 2-way valve and is controlled by the control device 12. At the second control valve 9 b, the first partial coolant line 81 branches into a third partial coolant line 83 and a fourth partial coolant line 84; in the first switching position of the second control valve 9 b, coolant is conducted into the third partial coolant line 83 and in the second switching position into a fourth partial coolant line 84, provided that the first control valve 9 ais switched into the first switching position and the cam 6 of the crankshaft 34 actuates the coolant pump 7.Equivalent to FIG. 2, the crankshaft 34 in FIG. 3 may also be connected to an additional camshaft to drive the coolant pump 7. Furthermore, as an alternative to FIG. 3, an embodiment of the cooling system 2 can also provide coolant for different regions of the two cylinders 3 a, 3 b. In a further alternative embodiment to FIG. 3, coolant can also be provided for different regions on only one cylinder 3 aor 3 b. It is clear that, according to the embodiment with two cylinders, in an internal combustion engine with more than two cylinders, more than two cylinders and / or more than two regions on one or different cylinders can also be cooled by means of the cooling system 1 according to the invention.In a further embodiment of the cooling system 1 according to the invention as shown in FIG. 4, a distributor valve 15 designed as a rotary valve is used to cool the cylinders 3 a, 3 b, 3 cof an internal combustion engine 2 arranged in series. The distributor valve 15 has a mechanical connection 16 to the crankshaft 34 of the internal combustion engine 2, or, according to FIG. 2, to a camshaft 13 connected to the crankshaft 34, and coolant flows against the distributor valve 15 via a fifth coolant line 85. The distribution valve 15 can be integrated directly into a conventional cooling system of the internal combustion engine and can be arranged upstream or downstream of the internal combustion engine. At the distributor valve 15, the fifth partial coolant line 85 branches into the sixth 86, seventh 87 and eighth partial coolant line 88.In a method for cooling the internal combustion engine, the distribution valve 15 is driven in accordance with the rotation of the crankshaft 34 or the camshaft 13, so that coolant is successively conducted to the sixth 86, seventh 87 and eighth partial coolant line 88 that conduct (not shown here) spraying devices on the cylinders 3 a, 3 band 3 c.List of reference characters1 Cooling system 2 Internal combustion engine 3 aFirst cylinder 3 bSecond cylinder 31 Combustion chamber 32 Piston 33 Crank 34 Crankshaft 4 Inlet valve 5 Outlet valve 6 Cam 7 Coolant pump 8 First coolant line 81 First partial coolant line 82 Second partial coolant line 83 Third partial coolant line 84 Fourth partial coolant line 85 Fifth partial coolant line 86 Sixth partial coolant line 87 Seventh partial coolant line 88 Eighth partial coolant line 9 aFirst control valve 9 bSecond control valve 10 aFirst spray device 10 bSecond spray device 11 Surge tank 12 Control device 13 Camshaft 14 Cam 15 Distributor valve 16 Mechanical connection

Claims

Cooling system (1) of an internal combustion engine (2) having at least one cylinder (3a, 3b), comprising a first coolant line (81) having at least one device which is in frictional connection with the crankshaft of the internal combustion engine (34) and is intended for regulating the flow of a coolant (7, 9a, 9b, 15), and a spraying device for applying a spray jet to the outer wall of a region of the internal combustion engine (10a, 10b), characterized in that the cooling system (1) is assigned to an internal combustion engine (2) which has at least one first (3a) and one second cylinder (3b) and at least one first directional control valve (9a) and one second directional control valve (9b), in which the first coolant line (8) branches at the first directional control valve (9a) into a first partial coolant line (81) leading to the second directional control valve (9b) and a partial coolant line (82) leading to a compensation tank second (11), and the first partial coolant line (8a) branches at the second directional control valve (9b) into a third partial coolant line (83) assigned to the first cylinder (3a) and a fourth partial coolant line (84) assigned to the second cylinder (3b).Cooling system (1) according to claim 1, wherein the means for regulating is a coolant pump.Cooling system (1) according to claim 1 or 2, wherein the means for regulating is a control valve.Cooling system (1) according to claim 3, wherein the control valve is a directional control valve (9a, 9b).The cooling system (1) according to claim 3, wherein the control valve is a rotary valve (15).Cooling system (1) according to claim 5, wherein the cooling system (1) is associated with an internal combustion engine (2) having at least a first (3a) and a second cylinder (3b), and a pressurized fifth partial coolant line (8) at the rotary valve (15) branches into at least a sixth partial coolant line (86) associated with the first cylinder (3a) and a seventh partial coolant line (87) associated with the second cylinder.Cooling system (1) according to one of the preceding claims, in which the cooling system (1) is assigned to an internal combustion engine (2) produced by an additive method.Motor vehicle having a cooling system according to one of Claims 1-7.Method for cooling an internal combustion engine with a cooling system according to one of Claims 1 - 7, wherein at least one valve (9a, 9b) and / or a coolant pump (7) are actuated by cams (6) of the crankshaft (34) of the internal combustion engine (2) or a camshaft 13 connected to the crankshaft (34) as a function of the crank angle and provide a flow of coolant to an injection device (10a, 10b).Method according to Claim 9, wherein the flow of the coolant to a specific spraying device (10a, 10b) is made possible by actuating the valves (9a, 9b) in a crank angle-dependent manner.Method according to Claim 9 or 10, wherein the flow of the coolant to the injection device (10a, 10b) is made possible by actuating the coolant pump (7) in a crank angle-dependent manner.

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