Oil supply system for an internal combustion engine and method for supplying oil to an internal combustion engine

Abstract

Oil supply system for an internal combustion engine (20) of a motor vehicle, with a main sump (16) for collecting engine oil, a secondary sump (12) for collecting engine oil, a first return line (28) opening into the secondary sump (12) for returning engine oil from combustion cylinders (22) of the internal combustion engine (20), a second return line (30) opening into the main sump (16) for returning engine oil passed through combustion cylinders (22) of the internal combustion engine (20) and through the internal combustion engine (20) and a conveying device (18) communicating with the main sump (16) and the secondary sump (12) for conveying engine oil to the internal combustion engine (20), wherein an internal combustion engine (20) having a combustion cylinder (22) is provided, wherein engine oil conveyed by the conveying device (18) for cooling and / or lubricating the combustion cylinders (22) in a first oil circuit (26) can be fed to the first return line (28) and engine oil conveyed by the conveying device (18) past the combustion cylinders (22) through the internal combustion engine (20) in a second oil circuit (27) can be fed to the second return line (30), characterized in that the internal combustion engine (20) has a crankshaft chamber (24) provided in the second oil circuit (27), wherein the conveying device (18) is designed to convey predominantly from the secondary sump (12) at least for the cold start of the internal combustion engine (20).

Description

[0001] The invention relates to an oil supply system for an internal combustion engine and a method for supplying oil to an internal combustion engine, with the aid of which an internal combustion engine of a motor vehicle can be cooled and / or lubricated with engine oil.

[0002] DE 10 2005 012 073 A1 shows an oil supply system with the features of the preamble of claim 1.

[0003] GB 2 251 889 A discloses an oil supply system for a motor vehicle internal combustion engine, in which all of the engine oil supplied to the internal combustion engine in an oil circuit is fed from the internal combustion engine to a smaller secondary sump, which is connected to a larger main sump via an overflow. An oil pump is connected to the main sump via a main line and to the secondary sump via a secondary line, with approximately 90% of the oil volume flow being drawn in from the secondary sump. This allows the internal combustion engine to be quickly heated up during a cold start phase using already warmed engine oil, while simultaneously gradually mixing the engine oil with cooler engine oil from the main sump.

[0004] There is a constant need to quickly warm up a motor vehicle's combustion engine to operating temperature after a cold start.

[0005] The object of the invention is to show measures that enable a rapid heating of an internal combustion engine of a motor vehicle to operating temperature.

[0006] The object is achieved according to the invention by an oil supply system having the features of claim 1 and a method having the features of claim 8. Preferred embodiments of the invention are specified in the subclaims and the following description, which can each represent an aspect of the invention individually or in combination.

[0007] According to the invention, an oil supply system for an internal combustion engine of a motor vehicle is provided, comprising a main sump for receiving engine oil, a secondary sump for receiving engine oil, a first return line opening into the secondary sump for returning engine oil from combustion cylinders of the internal combustion engine, a second return line opening into the main sump for returning engine oil passed through the internal combustion engine past combustion cylinders of the internal combustion engine, and a conveying device communicating with the main sump and the secondary sump for conveying engine oil to the internal combustion engine, wherein an internal combustion engine having combustion cylinders is provided,wherein engine oil conveyed by the conveying device for cooling and / or lubricating the combustion cylinders in a first oil circuit can be fed to the first return line and engine oil conveyed by the conveying device past the combustion cylinders through the internal combustion engine in a second oil circuit can be fed to the second return line, wherein the internal combustion engine has a crankshaft chamber provided in the second oil circuit, wherein the conveying device is designed to convey predominantly from the secondary sump, at least for cold starting of the internal combustion engine.

[0008] The engine oil delivered to the combustion engine can be divided into at least two different oil circuits, which run along different paths through the combustion engine. The engine oil fed along the combustion cylinders can be returned to the secondary sump, while the remaining engine oil delivered by the combustion engine is returned to the main sump. This takes advantage of the knowledge that during the cold start phase of an internal combustion engine, a temperature increase initially occurs with a particularly high temperature gradient in the combustion cylinders, where a fuel / air mixture is burned in a highly exothermic chemical reaction. The engine oil fed along the combustion cylinders is heated up considerably due to the very high temperatures that quickly arise in the combustion cylinders.Other parts of the internal combustion engine that are spaced apart from the combustion cylinders and to which engine oil is also supplied, such as a crankshaft chamber, are heated only very slowly because the heat generated in the combustion cylinders must first reach the other areas of the internal combustion engine in order to gradually heat these parts as well.

[0009] Because the engine oil that has come into thermal contact with the combustion cylinders is fed to the secondary sump, while the remaining, less heated engine oil is fed to the main sump, the temperature of the engine oil in the secondary sump can heat up significantly faster than if all of the engine oil flows through the combustion engine were consolidated into the secondary sump. This prevents the engine oil, heated by the combustion cylinders and returned via the first return line, from being cooled by the remaining engine oil fed through the combustion engine. Instead, the remaining engine oil is fed via the second return line past the secondary sump into the main sump, where the engine oil in the main sump can be gradually heated. However, the temperature of the engine oil in the secondary sump increases significantly faster during the cold start phase of the combustion engine than in the main sump.Since the delivery device can deliver predominantly from the secondary sump, preferably exclusively from the secondary sump for as long as possible, engine oil with a particularly high temperature is supplied to the internal combustion engine. This temperature can be maximum compared to engine oil in other areas upstream of the internal combustion engine. The internal combustion engine can therefore be heated to operating temperature more quickly than if the entire volume flow of oil from the internal combustion engine were fed back into the internal combustion engine. By branching off the engine oil, which is guided past the combustion cylinders at a distance, into the main sump, the engine oil, which is particularly heated by the combustion cylinders, can be fed from the secondary sump to the internal combustion engine, thus enabling a motor vehicle's internal combustion engine to heat up to operating temperature quickly.

[0010] During the cold start phase, the delivery device can feed a large portion of the oil volume flow delivered to the combustion engine, preferably the entire oil volume flow, from the secondary sump. This takes advantage of the knowledge that high oil pressures are not usually required immediately after the combustion engine has started, so that the intake volume of the secondary sump, which is smaller than the main sump, can be sufficient to feed the combustion engine. For example, it is not yet necessary to cool and / or lubricate an exhaust gas turbocharger with a significant oil volume flow. If the fill level of the secondary sump becomes too low and / or a desired oil pressure is not reached, the delivery device can supply an oil volume flow fed from the main sump.A pumping device designed to pump predominantly from the secondary sump is therefore understood to mean, in particular, a pumping device that, as far as possible under the given boundary conditions, pumps only from the secondary sump up to a maximum pumping capacity specified for the secondary sump and only covers an oil volume flow from the main sump that can no longer be served from the secondary sump. If the pumping device pumps a larger oil volume flow than required, it is preferably provided that the excess portion of the oil volume flow is diverted via a short-circuit line into the secondary sump and / or the main sump.

[0011] The oil volume flow coming from the delivery device can be divided into the first oil circuit and the second oil circuit, with part of the first oil circuit and part of the second oil circuit being formed by the internal combustion engine. The engine oil of the first oil circuit can carry out a heat exchange with the combustion cylinders, whereas the engine oil of the second oil circuit cannot do this or can only do so to a negligible extent. The engine oil of the second oil circuit can be used to lubricate the crankshaft and from there can drip into the main sump. The second return line can thus be formed through the wall of the crankshaft chamber without the need for a separate collection of the dripped engine oil in a separate line. The main sump can be connected to the crankshaft chamber below the crankshaft chamber in the direction of gravity.The secondary sump can be provided in an area that is not directly accessible from the crankshaft chamber, in particular in a secluded area, which can in particular only be reached via the first return line of engine oil.

[0012] In particular, the secondary sump is connected to the main sump via an overflow for allowing engine oil to overflow from the secondary sump into the main sump, wherein in particular a holding volume of the secondary sump is smaller than a holding volume of the main sump. After the operating temperature of the internal combustion engine has been reached, a higher oil pressure is usually required and / or a particularly high engine oil temperature is no longer desired. In particular during regular operation of the internal combustion engine, a higher proportion of the engine oil can therefore be fed from the main sump. This can result in less engine oil being withdrawn from the secondary sump than is returned via the first return line. In this situation, the fill level of the secondary sump can become so high that the engine oil flows from the secondary sump via the overflow into the main sump.

[0013] In particular, a portion A of the total oil volume flow delivered by the delivery device can be returned via the first return line, with 50% ≤ A ≤ 90%, in particular 55% ≤ A ≤ 80%, and preferably 60% ≤ A ≤ 70%. A large portion of the total oil volume flow can thus be delivered to the combustion cylinders, so that the secondary sump cannot dry out so quickly during the cold start phase.

[0014] The delivery device preferably has a constant stage for delivering a constant oil volume flow and a control stage for delivering a variable oil volume flow, with the constant stage drawing in oil from the secondary sump and the control stage drawing in oil from the main sump. This takes advantage of the fact that during the cold start phase, particularly high oil pressure is not required and delivery from the constant stage is sufficient to heat the combustion engine to operating temperature. The constant stage can therefore ensure or even exceed a minimum oil volume flow. If higher oil pressures are required during regular operation of the combustion engine at operating temperature, the control stage can provide the additional oil volume flow. If the secondary sump runs dry during the cold start phase, the oil volume flow not supplied from the secondary sump can be substituted by the control stage from the main sump.For this purpose, for example, the oil pressure in a main oil gallery of the combustion engine can be measured, whereby a sudden drop in the oil pressure can indicate a suction of air in the secondary sump, which can trigger the activation of the control stage.

[0015] Particularly preferably, the control stage is designed for the selective delivery of engine oil delivered by the constant stage into the main sump. The control stage can thus effect negative amplification by delivering a portion of the engine oil delivered by the constant stage to the main sump against the designated flow direction. This also makes it possible to achieve an oil volume flow delivered to the combustion engine that is lower than the oil volume flow delivered by the constant stage. The suction side of the control stage, which communicates with the main sump, can be operated as the pressure side for this purpose. The control stage is designed, for example, as a vane pump that can be operated as a pump in both directions of rotation.

[0016] In particular, the delivery device is connected to a secondary oil circuit, in particular for cooling and / or lubricating an exhaust gas turbocharger, wherein the secondary oil circuit is connected to the secondary sump via a third return line. The delivery device can thus also supply engine oil to an oil circuit that does not run through the combustion engine but supplies an auxiliary unit with engine oil. During the cold start phase, the oil volume flow delivered to the exhaust gas turbocharger is generally negligible compared to the oil volume flow coming from the first return line.

[0017] The invention further relates to a method for supplying oil to an internal combustion engine of a motor vehicle with the aid of an oil supply system which can be designed and developed as described above, in which immediately after the start of the motor vehicle engine, only engine oil is pumped from the secondary sump to the motor vehicle engine in order to heat the motor vehicle engine and after an operating temperature of the internal combustion engine has been reached, engine oil is pumped from both the secondary sump and the main sump, wherein in particular a pumped total oil volume flow is lower before the operating temperature is reached than after the operating temperature is reached.By diverting the engine oil, which is guided at a distance past the combustion cylinders, into the main sump, the engine oil, which is particularly heated by the combustion cylinders, can be fed from the secondary sump to the internal combustion engine, so that a rapid heating of the internal combustion engine of a motor vehicle to operating temperature is possible.

[0018] In particular, in the event of an insufficient fill level in the secondary sump during the engine warm-up to operating temperature and / or an insufficient oil delivery pressure applied to the engine during the engine warm-up to operating temperature, an additionally required oil volume flow is pumped from the main sump. This ensures a sufficient oil volume flow even if the fill level in the secondary sump is temporarily insufficient.

[0019] The invention will now be explained by way of example with reference to the accompanying drawings using a preferred embodiment, wherein the features presented below may represent an aspect of the invention, both individually and in combination. It shows: Fig. 1: a schematic diagram of an oil supply system.

[0020] The Fig.The oil supply system 10 shown in Figure 1 has a smaller secondary sump 12, which communicates with a larger main sump 16 via an overflow 14. The engine oil provided in the secondary sump 12 and in the main sump 16 can be supplied to an internal combustion engine 20 with the aid of a conveying device 18. The internal combustion engine 20 has a plurality of combustion cylinders 22 and a crankshaft chamber 24. The combustion cylinders 22 are supplied with engine oil via a first oil circuit 26 in order to cool and / or lubricate the combustion cylinders 22. The engine oil conveyed in the first oil circuit 26 is supplied to the secondary sump 12 via a first return line 28. The remaining engine oil delivered by the internal combustion engine 20 is fed, for example, to the crankshaft chamber 24 via a second oil circuit 27 and finally fed to the main sump 16 via a second return line 30 formed, for example, through the crankshaft chamber 24.If necessary, the delivery device 18 can supply auxiliary units, such as the exhaust gas turbocharger 34, with engine oil via a secondary oil circuit 32. In particular, the engine oil coming from the exhaust gas turbocharger 34 can be fed to the secondary sump 12 via a third return line 35.

[0021] The delivery device 18 has different delivery stages for sucking engine oil from the secondary sump 12 and the main sump 16. For this purpose, the delivery device 18 can have a constant stage 36 that can suck a substantially constant oil volume flow from the secondary sump 12. The delivery device 18 additionally has a controllable control stage 38 that can suck a variable oil volume flow from the main sump 16.

[0022] Particularly during a cold start of the internal combustion engine 20, the delivery device 18 predominantly, in particular exclusively, delivers engine oil from the secondary sump 12 to the internal combustion engine 20 using the constant stage 36. Since the particularly highly heated engine oil from the first oil circuit 26 is delivered to the secondary sump 12, while the less highly heated engine oil from the second oil circuit 27 is fed to the main sump 16, the internal combustion engine 20 heats up to operating temperature particularly quickly. If the secondary sump 12 should run dry, the missing oil volume flow can be supplied via the control stage 38. If too much engine oil is delivered via the constant stage 36, the control stage 38 can be operated against its designated delivery direction and drain the excess engine oil into the main sump 16.

Claims

[1] Oil supply system for an internal combustion engine (20) of a motor vehicle, with a main sump (16) for collecting engine oil, a secondary sump (12) for collecting engine oil, a first return line (28) opening into the secondary sump (12) for returning engine oil from combustion cylinders (22) of the internal combustion engine (20), a second return line (30) opening into the main sump (16) for returning engine oil passed through combustion cylinders (22) of the internal combustion engine (20) and through the internal combustion engine (20) and a conveying device (18) communicating with the main sump (16) and the secondary sump (12) for conveying engine oil to the internal combustion engine (20), wherein an internal combustion engine (20) having a combustion cylinder (22) is provided, wherein engine oil conveyed by the conveying device (18) for cooling and / or lubricating the combustion cylinders (22) in a first oil circuit (26) can be fed to the first return line (28) and engine oil conveyed by the conveying device (18) past the combustion cylinders (22) through the internal combustion engine (20) in a second oil circuit (27) can be fed to the second return line (30), characterized by , that the internal combustion engine (20) has a crankshaft chamber (24) provided in the second oil circuit (27), wherein the conveying device (18) is designed to convey predominantly from the secondary sump (12) at least for the cold start of the internal combustion engine (20). [2] Oil supply system according to claim 1, wherein the secondary sump (12) is connected to the main sump (16) via an overflow (14) for allowing engine oil to overflow from the secondary sump (12) into the main sump (16), wherein in particular a receiving volume of the secondary sump (12) is smaller than a receiving volume of the main sump (16). [3] Oil supply system according to one of claims 1 to 2 characterized by that a portion A of a total oil volume flow conveyed by the conveying device (18) can be returned via the first return line (28), wherein 50% ≤ A ≤ 90%, in particular 55% ≤ A ≤ 80% and preferably 60% ≤ A ≤ 70% applies. [4] Oil supply system according to one of claims 1 to 3 characterized bythat the conveying device (18) has a constant stage (36) for conveying a constant oil volume flow and a control stage (38) for conveying a variable oil volume flow, wherein the constant stage (36) sucks from the secondary sump (12) and the control stage (38) sucks from the main sump. [5] Oil supply system according to claim 4 characterized by that the control stage (38) is designed for the selective delivery of engine oil delivered by the constant stage (36) into the main sump (16). [6] Oil supply system according to one of claims 1 to 5 characterized by that the conveying device (18) is connected to a secondary oil circuit (32), in particular for cooling and / or lubricating an exhaust gas turbocharger (34), wherein the secondary oil circuit (32) is connected to the secondary sump (12) via a third return line (35). [7] Method for supplying oil to an internal combustion engine (20) of a motor vehicle using an oil supply system (10) according to one of claims 1 to 6, in which immediately after the start of the motor vehicle engine (20) only engine oil is pumped from the secondary sump (12) to the motor vehicle engine (20) in order to heat the motor vehicle engine (20) and after the internal combustion engine (20) has reached an operating temperature, engine oil is pumped from both the secondary sump (12) and the main sump (16), wherein in particular a total oil volume flow delivered before reaching the operating temperature is lower than after reaching the operating temperature. [8] Method according to claim 7, wherein in the case of an insufficient fill level in the secondary sump (12) during heating of the internal combustion engine (20) to the operating temperature and / or an insufficient oil delivery pressure applied to the internal combustion engine (20) during heating of the internal combustion engine (20) to the operating temperature, an additionally required oil volume flow is delivered from the main sump (16).

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