Method for operating an internal combustion engine and apparatus for carrying out such a method

Abstract

Method for operating an internal combustion engine (1) in which a first piston cooling nozzle (3) per cylinder (2) and at least one further piston cooling nozzle (4) per cylinder (2) are successively activated as required for sufficient cooling of one or more components of the internal combustion engine (1), characterized in that the first piston cooling nozzle (3) is activated via a first switching valve (14) and the at least one further piston cooling nozzle (4) is activated via a second switching valve (21), wherein in the case of the internal combustion engine (1) with several cylinders (2) the respective first piston cooling nozzles (3) are activated jointly via the first switching valve (14) and the respective at least one further piston cooling nozzle (4) are activated jointly via the second switching valve (21).

Description

[0001] The invention relates to a method for operating an internal combustion engine and a device for carrying out such a method.

[0002] The increase in the specific power of internal combustion engines, such as combustion engines, places greater demands on their lubrication systems, which also includes the cooling of highly stressed components. At the same time, frictional power optimization requires regulating the oil pressure and oil flow rate as well as the so-called engine scavenging behavior as needed to minimize the drive power required for the oil pump. Engine scavenging behavior refers to the volume of oil circulated by the engine at a given oil pressure.

[0003] DE 10 2005 006 054 A1 discloses a method for operating a reciprocating internal combustion engine with a piston cooling device. In this method, a switching valve for controlling the amount of oil for cooling a piston is controlled by a device from a control unit, and the oil flow is controlled by the device, for example, an oil spray nozzle, depending on the operating point. This document also discloses that a switching valve controls a group of cylinders or all piston cooling devices together.

[0004] DE 10 2011 007 605 A1 discloses an oil supply system for a reciprocating piston internal combustion engine, in which one or more piston cooling nozzles are provided for each piston. The oil supply to the piston cooling nozzle is always via a pressure-operated valve, namely a check valve. The oil supply system operates depending on the oil pressure supplied by a pump. This pressure is controlled so that it either remains below a predefined valve opening pressure during engine operation, which does not require piston cooling, or is above the predefined valve opening pressure when piston cooling is required. In the case of the aforementioned low-pressure operating mode, the piston cooling nozzles are deactivated; in the case of a high-pressure operating mode, the piston cooling nozzles are activated.

[0005] DE 10 2011 085 444 A1 discloses a method for operating an internal combustion engine, in which a piston is cooled by means of at least two spray nozzles.

[0006] DE 10 2004 017 909 A1 describes a device for cooling the pistons of an internal combustion engine by means of a lubricating oil pump which supplies oil from the lubricating oil circuit to each piston via a supply line having an outlet opening at least on the bottom side, wherein the oil supply takes place via at least one valve.

[0007] Internal combustion engines with oil supply systems are known in practice. These systems are either continuously open or simultaneously controlled by check valves that open at a defined oil pressure. However, this results in limited freedom in the design of the operating strategy, resulting in unnecessarily high pump drive power and thus higher carbon dioxide (CO2) emissions. Furthermore, these check valves are subject to high pressure losses. This, in turn, negatively impacts the engine's frictional power and thus its fuel consumption.

[0008] The invention is based on the object of providing a method of the type mentioned above by means of which an internal combustion engine, particularly with regard to its cooling, can be operated more flexibly and in a more environmentally friendly manner. The invention is also based on the object of providing a device for carrying out such a method.

[0009] This object is achieved according to the invention by a method having the features of claim 1, and by a device of the above-mentioned type having the features characterized in claim 4. Advantageous embodiments are described in the respective dependent claims.

[0010] The method according to the invention is designed such that a first piston cooling nozzle per cylinder and at least one further piston cooling nozzle per cylinder are activated sequentially as needed to ensure sufficient cooling of one or more components of the internal combustion engine. The invention is based on the idea of ​​switching several piston cooling nozzles provided per cylinder in stages depending on the cooling requirement and thus sequentially. Such sequential activation of the several piston cooling nozzles provided per cylinder enables extensive adaptation of the cooling to the cooling requirement; this provides more freedom in designing the operating strategy than in the prior art embodiments.In addition, such a method effectively prevents either insufficient or excessive cooling, since, depending on the cooling requirement, none, one, or several piston cooling nozzles can be activated per cylinder. The piston cooling nozzles can be designed such that the pistons are sprayed with engine oil from below, or the piston cooling nozzles are designed such that the engine oil sprays the pistons continuously. Furthermore, the piston cooling nozzles can be designed such that the pistons are only sprayed with engine oil when the respective pistons are at the bottom, i.e. at their bottom dead center. Additionally or alternatively, it can be provided that the piston cooling nozzles are designed to spray engine oil at different pressures, so that the pistons are sprayed evenly with engine oil in the lower and upper regions.Alternatively, piston cooling nozzles can be provided for spraying the pistons from below, and additional piston cooling nozzles for spraying the pistons further up. This also provides greater freedom in the design of the oil pump, making it easier to optimize.

[0011] Furthermore, the piston cooling nozzles are activated via at least one switching valve. Such a valve can be controlled very flexibly, further increasing the degrees of freedom with regard to the operating strategy. This is due to the fact that the degrees of freedom with regard to the activation timing are significantly greater with a switching valve compared to a check valve. Furthermore, a switching valve results in lower pressure losses than with a check valve, which ultimately leads to lower oil pump drive power and lower engine friction loss, and thus to lower fuel consumption.

[0012] In addition, the first piston cooling nozzle is activated via a first switching valve, and the at least one additional piston cooling nozzle is activated via a second switching valve. The use of these switching valves has the advantage that all first piston cooling nozzles can be activated with one switching valve, and the additional piston cooling nozzles can be activated jointly with the additional switching valve. Therefore, only one switching valve is required for a plurality of first or second piston cooling nozzles. This can be advantageous when space is limited in the crankcase.

[0013] Furthermore, in an internal combustion engine with multiple cylinders, the first piston cooling nozzles are activated jointly via the first switching valve, and at least one additional piston cooling nozzle is activated jointly via the second switching valve. In this respect, piston cooling can be largely adapted to the operating and space conditions of the respective internal combustion engine.

[0014] According to a further development of the invention, the piston cooling nozzles are activated depending on various operating parameters of the internal combustion engine, such as its torque and speed. Preferably, the first piston cooling nozzle is activated near maximum torque at low / medium speeds, and the at least one additional piston cooling nozzle is gradually activated at higher loads such as higher speeds. This allows the required oil quantity to be easily adapted to the cooling requirements of the piston(s) of the internal combustion engine. The cooling requirements of the piston(s) can be determined based on the operating parameters and / or a characteristic map, given available test results.

[0015] In terms of the device, the internal combustion engine has an oil supply device to which the first and at least one further piston cooling nozzle as well as the valves activating the piston cooling nozzles are connected, and a control device which controls at least some of the valves depending on the operating parameters of the internal combustion engine for the purpose of activating the piston cooling nozzles as needed and supplying the latter with oil. In the case of an internal combustion engine with several cylinders, the first piston cooling nozzles can be activated jointly via the first switching valve and the at least one further piston cooling nozzle can be activated jointly via the second switching valve. Such a device is particularly advantageous in internal combustion engines which place high demands on the cooling of pistons and cylinder lands. Furthermore, such a device is easily adaptable to the current cooling requirement since the individual piston cooling nozzles can be activated or deactivated quickly.can be deactivated.

[0016] According to another refinement, the control device is designed such that the valves are controlled based on current operating parameters of the internal combustion engine and predetermined characteristic maps. This allows for flexible adjustment of the required oil quantity and helps ensure that only as much oil is circulated in the engine as is necessary for the current operating situation. This also largely prevents operating situations that result in excessive cooling of the relevant engine components.

[0017] According to an advantageous development, the oil supply device has a first oil gallery to which the respective first piston cooling nozzles of the cylinders are connected, wherein the oil supply device preferably has a second oil gallery to which the at least one further piston cooling nozzle of the cylinders is connected. Such oil galleries form, in a sense, a collecting line to which the individual piston cooling nozzles can be connected via comparatively short supply channels. This allows the internal combustion engine to be designed very compactly. Furthermore, an oil gallery largely ensures that the oil temperature at the piston cooling nozzles connected to it is as uniform as possible. Such an embodiment enables and supports demand-based cooling of each piston.

[0018] The invention is explained in more detail below with reference to the drawing, which shows Fig. 1 is a schematic, partially sectioned view of a part of an internal combustion engine; and Fig. 2 is a schematic, partially sectioned view of part of an internal combustion engine according to an embodiment.

[0019] In Fig. 1 is a schematic representation of an internal combustion engine 1, partly in section. It is pointed out that in the Fig. 1 and Fig. 2 The diagonal hatching symbolising a section has been omitted for the sake of clarity.

[0020] In Fig. 1, the internal combustion engine 1 has four cylinders 2. A first piston cooling nozzle 3 and a second piston cooling nozzle 4 are provided for each cylinder. It should be noted that more than two piston cooling nozzles may be provided per cylinder.

[0021] The first and second piston cooling nozzles 3, 4 can spray the piston with engine oil from below, or the first and second piston cooling nozzles 3, 4 are designed such that the engine oil sprays the pistons continuously. Furthermore, the first and second piston cooling nozzles 3, 4 can be designed such that the pistons are only sprayed with engine oil when the respective pistons are at the bottom, i.e. at their bottom dead center. Additionally or alternatively, it can be provided that the first and second piston cooling nozzles 3, 4 are designed to spray engine oil at different pressures so that the pistons are sprayed evenly with engine oil in their lower and upper regions. Alternatively, for example, the first piston cooling nozzles 3 can be arranged to spray the pistons from below and the second piston cooling nozzles 4 can be arranged to spray the pistons further up.

[0022] The first piston cooling nozzles 3 are each connected to a common oil gallery 6 via a first supply channel 5.

[0023] Furthermore, the second piston cooling nozzles 4 are in fluid connection with the oil gallery 6 via second supply channels 7, wherein Fig. 1 a valve 10 is installed in each of the second guide channels 7. In Fig. 1, the valve 10 is a pressure-operated check valve 11.

[0024] First and second supply channels 5, 7 and the oil gallery 6 are in Fig. 1 shown in dashed lines.

[0025] The oil gallery 6 belongs to an oil supply device 12, which also includes an oil system 13 and a switching valve 14, both of which are connected to the oil gallery 6 via oil lines 15. Furthermore, a control device 16 is provided, which is connected to the switching valve 14 via an electrical line 17.

[0026] The oil system 13 also includes, for example, a pump (not shown in detail), which pumps the oil from an oil container (not shown) also belonging to the oil system 13 via the oil lines 15 and the switching valve 14 to the oil gallery 6 and from there into the first supply channels 5 and possibly also the second supply channels 7 up to the first piston cooling nozzles 3 and possibly the second piston cooling nozzles 4.

[0027] In the Fig. In the embodiment shown in Figure 2, the same reference numerals are used for the same features.

[0028] According to Fig. 2, in addition to the oil gallery 6, referred to here as the first oil gallery, a second oil gallery 20 is provided, to which the second supply channels are connected. Thus, the second piston cooling nozzles 4 are in fluid communication with the second oil gallery 20.

[0029] Furthermore, a second switching valve 21 is provided, which is connected via a further oil line 22 on the one hand to the second oil gallery 20 and on the other hand to the oil system 13.

[0030] In addition, the control device 16 is connected to the second switching valve 21 via a further electrical line 23.

[0031] It is clear that a pump (not shown in detail) pumps the oil in the case of the Fig. 2, via the oil lines 15, 22 and the switching valves 14, 21 to the first oil gallery 6 and the second oil gallery 20, respectively. From the first oil gallery 6, the oil then reaches the first piston cooling nozzles 3 via the first supply channels 5, whereas the oil from the second oil gallery 20 reaches the second piston cooling nozzles 4 via the second supply channels 7.

[0032] The method according to the invention for operating the internal combustion engine 1 is described below with reference to Fig. 2 explained.

[0033] In the method according to the invention, a first piston cooling nozzle 3 and at least one further piston cooling nozzle, hereinafter referred to as the second piston cooling nozzle 4, are used per cylinder 2. It is clear that, unlike in Fig. 1 and Fig. 2, more than two piston cooling nozzles can be provided per cylinder.

[0034] According to the invention, first and second piston cooling nozzles 3, 4 are activated sequentially as needed to ensure adequate cooling of one or more components of the internal combustion engine 1. Demand-based activation refers to the activation of the piston cooling nozzles as a function of various operating parameters of the internal combustion engine 1, such as its torque and speed. Preferably, the first piston cooling nozzles 3 are activated near maximum torque at low / medium speeds. Low / medium speeds are understood to mean speeds up to approximately 3000 revolutions per minute. The second piston cooling nozzles 4 are gradually activated at higher loads, such as additionally higher speeds, preferably above 3000 revolutions per minute.

[0035] According to Fig. 1, the oil flows from the oil system 13 via the oil line 15 and the switching valve 14 into the oil gallery 6, also called the piston cooling gallery. From there, the oil is directed via the first supply channels 5 to the continuously open first piston cooling nozzles 3, from where the oil can feed the oil channel (not shown in detail) in the piston for cooling.

[0036] In this respect, the first piston cooling nozzles 3 are activated via at least one switching valve, namely the switching valve 14. The switching valve 14 is controlled by the control device 16 via the electrical line 17 based on current operating parameters of the internal combustion engine 1 and predetermined characteristic maps.

[0037] As further stated in Fig. As shown in Figure 1, the second piston cooling nozzles 4 are each activated via a valve 10, namely the check valves 11. The check valves 11 open as soon as the oil pressure in the oil supply device 12 exceeds a certain threshold value.

[0038] In the Fig. 2, the oil guidance and control of the first piston cooling nozzles 3 corresponds to that shown in Fig. 1. The second piston cooling nozzles 4 are arranged according to Fig. 2 is activated via the second oil gallery 20 and the second switching valve 21, whereby both switching valves 14, 21 are controlled by the control device 16. In this respect, in the second supply channels 7 in the Fig. 2 shown embodiment different from that in the Fig. 1 no check valves 11 provided.

[0039] In summary, in an internal combustion engine with several cylinders 2, the respective first piston cooling nozzles 3 are controlled jointly via the first switching valve 14 and the respective second piston cooling nozzles 4 are controlled either individually via respective valves 10, for example check valves 11 (see Fig. 1), or according to the invention jointly via the second switching valve 21 (see Fig. 2) activated.

[0040] A device according to the invention for carrying out the method described above is explained in more detail below.

[0041] The device comprises the oil supply device 12, to which the first and second piston cooling nozzles 3, 4 as well as the valves 14, 21 activating the piston cooling nozzles 3, 4 are connected, as shown in Fig. 2. The device further comprises the control device 16, which controls the valves, namely the switching valves 14 and 21, depending on the operating parameters of the internal combustion engine 1 for the purpose of activating the piston cooling nozzles 3, 4 as needed and supplying the latter with oil.

[0042] As previously indicated, the control device 16 is designed such that the valves, namely the switching valves 14, 21, are controlled based on current operating parameters of the internal combustion engine 1 and predetermined characteristic maps. The current operating parameters include, for example, the engine speed, the instantaneous engine torque, the coolant temperature, and / or the oil temperature. A predetermined characteristic map is, for example, a graph showing the torque curve versus the engine speed. The piston cooling nozzles, which are activated as needed here, serve in particular for piston cooling.

[0043] According to Fig. 1, the oil supply device 12 has a (first) oil gallery 6, to which the respective first piston cooling nozzles 3 of the cylinders 2 are connected. Fig. 2, the oil supply device 12 additionally has a second oil gallery 20, to which the respective second piston cooling nozzles 4 of the cylinders 2 are connected.

[0044] If the internal combustion engine, as in Fig. 2, two oil galleries 6, 20 are the following, from the representation of the in Fig. Different variants are possible compared to the embodiment shown in Figure 2.

[0045] On the one hand, the second oil gallery 20 can also be controlled via a central check valve (not shown). In this variant, the second piston cooling nozzles 4 are thus also activated simultaneously via the second oil gallery 20 through the central check valve.

[0046] According to another variant, also not shown, both galleries, namely the first oil gallery 6 and the second oil gallery 20, are each controlled, i.e. opened and closed, via a check valve at different opening pressures.

[0047] In the Fig. In the embodiment shown in Figure 2, the oil galleries 6, 20 are connected in parallel. According to a further variant not shown, it is also possible to provide a series connection of the oil galleries. Furthermore, unlike in the embodiment shown in Fig. 2 shown embodiment, it is possible to connect the first oil gallery 6 via a check valve and the second oil gallery 20, as shown in Fig. 2, via a switching valve. In this case, too, all piston cooling nozzles connected to the respective oil gallery are supplied with oil simultaneously.

[0048] This makes it possible to activate several cooling nozzles per cylinder in stages and according to the engine map. The method according to the invention and the device for carrying out the method can be used in high-performance engines that require high cooling performance. Due to the register circuit, the oil pump can be dimensioned relatively small, which results in lower fuel consumption. Furthermore, there are lower pressure losses in the oil path than in conventional systems with piston cooling. This creates a method for operating an internal combustion engine with which piston cooling can be carried out more flexibly and in a more environmentally friendly manner. A device for carrying out such a method is also described above. LIST OF REFERENCE SYMBOLS 1 internal combustion engine 2 cylinders 3 first piston cooling nozzle 4 second piston cooling nozzle 5 first supply channel 6 (first) Oil Gallery 7 second supply channel 10 Valve 11 Check valve 12 Oil supply device 13 Oil system 14 (first) switching valve 15 Oil pipeline 16 Control device 17 electrical cable 20 second oil gallery 21 second switching valve 22 additional oil pipelines 23 additional electrical lines

Claims

[1] Method for operating an internal combustion engine (1), in which a first piston cooling nozzle (3) per cylinder (2) and at least one further piston cooling nozzle (4) per cylinder (2) are activated one after the other as required for the purpose of adequately cooling one or more components of the internal combustion engine (1), characterized by that the first piston cooling nozzle (3) is activated via a first switching valve (14) and the at least one further piston cooling nozzle (4) is activated via a second switching valve (21), wherein in the internal combustion engine (1) with a plurality of cylinders (2), the respective first piston cooling nozzles (3) are activated jointly via the first switching valve (14) and the respective at least one further piston cooling nozzle (4) are activated jointly via the second switching valve (21). [2] Method according to claim 1, characterized by that the piston cooling nozzles (3, 4) are activated depending on different operating parameters of the internal combustion engine (1) such as its torque and speed. [3] Method according to claim 1 or 2, characterized by that the first piston cooling nozzle (3) is activated near the maximum torque at low / medium speeds and the at least one further piston cooling nozzle (4) is gradually switched on at higher loads such as additionally higher speeds. [4] Device arranged to carry out the method according to one of the preceding claims, characterized bythat an oil supply device (12), to which the first and the at least one further piston cooling nozzles (3, 4) as well as the valves (10, 11, 14, 21) activating the piston cooling nozzles (3, 4) are connected, and a control device (16) are provided which controls at least some of the valves (14, 21) as a function of the operating parameters of the internal combustion engine (1) for the purpose of activating the piston cooling nozzles (3, 4) as required and supplying the latter with oil, wherein in the internal combustion engine (1) with a plurality of cylinders (2), the respective first piston cooling nozzles (3) can be activated jointly via the first switching valve (14) and the respective at least one further piston cooling nozzle (4) can be activated jointly via the second switching valve (21). [5] Device according to claim 4, characterized bythat the control device (16) is designed such that the control of the valves (14, 21) takes place on the basis of current operating parameters of the internal combustion engine (1) and predetermined characteristic maps. [6] Device according to claim 4 or 5, characterized by that the oil supply device (12) has a first oil gallery (6) to which the respective first piston cooling nozzles (3) of the cylinders (3) are connected. [7] Device according to one of claims 4 to 6, characterized by that the oil supply device (12) has a second oil gallery (20) to which the at least one further piston cooling nozzle (4) of the cylinders (2) is connected.

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