Internal combustion engine with vacuum pump

Abstract

Internal combustion engine (2) comprising at least a crankcase (4) with an oil pan (6) and an electric vacuum pump (10), wherein the electric vacuum pump (10) is arranged inside the crankcase (4), and wherein the electric vacuum pump (10) is designed such that the electric vacuum pump (10) can be lubricated with oil (8) held in the oil pan (6), characterized in that a control electronics unit (12) for the electric vacuum pump (10) is arranged outside the crankcase (4), wherein the control electronics unit (12) and the electric vacuum pump (10) are connected via a cable connection (13), wherein the cable connection (13) is guided through an opening (15) of the crankcase (4), and wherein the opening (15) is sealed against oil.

Description

[0001] The invention relates to an internal combustion engine with a vacuum pump for generating a vacuum, which can be used in particular in a braking system of a motor vehicle. Furthermore, the invention relates to a motor vehicle with such an internal combustion engine and such a braking system.

[0002] In braking systems, especially for motor vehicles, it is common practice to increase braking force using a brake booster. This serves both driving safety and driver comfort. In conventional brake boosters, the braking force is amplified using a vacuum. This is, for example, the operating principle of so-called Mastervacs. The required vacuum is usually generated by a vacuum pump integrated into the vehicle's internal combustion engine.

[0003] Known systems utilize a mechanically driven vacuum pump. This typically runs continuously during operation of the internal combustion engine, regardless of whether vacuum is actually required during a particular operating phase. In operating phases that require no or only reduced vacuum, unnecessary energy is expended to generate the vacuum. This can have a detrimental effect on the energy balance and, in particular, on the fuel consumption of the internal combustion engine. Such a mechanical vacuum pump can be operated, for example, via the camshaft or crankshaft. Such a mechanical vacuum pump can be located, for example, on the cylinder head or near the crankshaft, for example, in the oil sump of the crankcase. Especially in the latter case, the mechanical vacuum pump can be lubricated by oil from the oil sump of the internal combustion engine.

[0004] DE 10 2012 020 618 B3 discloses a novel arrangement of a coolant pump for internal combustion engines. US 2007 0 221 160 A1 discloses a drive unit for a motorcycle. DE 10 2014 205 931 A1 discloses a modular system for a timing gear assembly. DE 102 14 635 A1 discloses a control device for an engine. US 2005 0 205 066 A1 discloses a vertical multi-cylinder diesel engine. DE 10 2006 008 736 B3 discloses an EMC shield for ignition coils. DE 10 2009 046 298 A1 discloses a fuel pump control device for a fuel supply system.

[0005] DE 10 2012 102 402 A1 discloses a mass balancing module with a housing attached to a crankcase. The mass balancing module with crankcase has a crankshaft, a balance shaft, and at least one further shaft for driving at least one auxiliary unit via a drive system. At least one auxiliary unit is arranged within the housing.

[0006] Based on this, the object of the present invention is to further solve or at least alleviate the technical problems described in connection with the prior art. In particular, an internal combustion engine with a vacuum pump is to be presented that is particularly advantageous with regard to its service life and the fuel consumption of the internal combustion engine.

[0007] These objects are achieved with an internal combustion engine according to the features of patent claim 1. Further advantageous embodiments of the internal combustion engine are specified in the dependent claims. The features listed individually in the claims can be combined with one another in any technologically expedient manner and can be supplemented by explanatory facts from the description, thereby demonstrating further embodiments of the invention.

[0008] The device according to the invention is an internal combustion engine comprising at least one crankcase with an oil pan and an electric vacuum pump. The electric vacuum pump is arranged within the crankcase. The electric vacuum pump is designed such that it can be lubricated with oil held in the oil pan.

[0009] The internal combustion engine is preferably intended for use in motor vehicles. One or more cylinders are preferably arranged on the crankcase of the internal combustion engine, which serve as combustion chambers in which fuel is burned with air during operation of the internal combustion engine. The crankshaft, which is driven by the cylinders, is located in the crankcase. The crankshaft is preferably lubricated with oil from an oil sump. This is preferably provided in the oil pan. The oil pan is preferably a lower region of the crankcase or the lower end of the crankcase. The crankcase as a whole, including the oil pan, is preferably sealed oil-tight.

[0010] The electric vacuum pump is preferably a pumping device suitable for generating a vacuum. The medium pumped by the electric vacuum pump is preferably air. This air is preferably purified, i.e., in particular, free of particles of a size sufficient to cause significant damage to the electric vacuum pump and associated components.

[0011] Preferably, the electric vacuum pump generates a vacuum for use in a braking system, particularly in a brake booster. Alternatively or additionally, the vacuum can be used for other applications requiring a vacuum, particularly within the motor vehicle.

[0012] The electric vacuum pump is preferably designed for operation with electric current. This means that, for example, an electric motor within the electric vacuum pump can drive components such as blades. This electric current is preferably provided by a power supply of the motor vehicle, in particular by an alternator and / or a battery. Furthermore, it is preferred that the power of the electric vacuum pump is tailored to requirements resulting from its use for generating a vacuum for a braking system of a motor vehicle. This relates in particular to a minimum pressure level achievable with the electric vacuum pump, which can be individually set with the electric vacuum pump.

[0013] The use of electric-driven vacuum pumps in a crankcase has been avoided so far because electrical wiring and components should not be exposed to the oil in the crankcase.

[0014] However, electric vacuum pumps have the advantage over mechanical vacuum pumps that they can be activated and deactivated.

[0015] With such vacuum pumps it is possible to provide vacuum only when vacuum is actually necessary, for example when a brake is applied and a brake booster is needed to increase the braking effect of the brake.

[0016] However, electric vacuum pumps have the disadvantage that they typically run dry. This is a significant disadvantage, especially compared to wet-running pumps in a crankcase. Due to their design, dry-running pumps are subject to much higher mechanical wear than wet-running pumps.

[0017] The approach of designing an electric vacuum pump as a wet-running pump and arranging it in a crankcase overcomes the disadvantages of both mechanical vacuum pumps and electric vacuum pumps.

[0018] On the one hand, mechanical wear on the vacuum pump can be significantly reduced. In the case of a vacuum pump in a motor vehicle, it is particularly possible to achieve a life cycle that is longer than or equal to the life cycle of the vehicle, so that replacing the vacuum pump during the vehicle's life cycle is no longer necessary. On the other hand, targeted activation and deactivation of the vacuum pump during operation is possible. This enables a reduction in a vehicle's fuel consumption.

[0019] The electric vacuum pump is preferably located in a lower region of the crankcase so that oil held in the oil pan can enter the vacuum pump. The oil serves for lubrication in the vacuum pump. For this purpose, the vacuum pump is provided with corresponding inlets. Lubrication here refers to the wetting of rubbing surfaces, particularly metallic components, with oil. Lubrication serves to reduce friction and frictional heat, improve running characteristics (e.g., by reducing noise and vibration emissions), and reduce wear.

[0020] According to the invention, control electronics for the electric vacuum pump are arranged outside the crankcase. The control electronics and the electric vacuum pump are connected via a cable connection, wherein the cable connection is routed through an opening in the crankcase, and wherein the opening is sealed against oil.

[0021] An arrangement outside the crankcase here also means and includes, in particular, an arrangement outside the oil pan. The control electronics arranged outside the crankcase can be designed with lower temperature resistance than the previously described control electronics arranged inside the crankcase because lower temperatures occur outside the crankcase than inside it. A lower required temperature resistance can, in particular, reduce costs for the control electronics. The control electronics arranged on the outside of the crankcase requires the control electronics and the electric vacuum pump to be connected via the cable connection. The cable connection is preferably a connection that is suitable for transmitting the electrical power required to operate the electric vacuum pump.The crankcase has an opening through which the cable connection is routed. This opening is usually formed in a wall of the crankcase. To prevent oil from leaking from the oil pan, the oil opening is sealed. This sealing of the oil opening is also referred to as "fluidic isolation."

[0022] In a further embodiment of the described internal combustion engine, control electronics for the electric vacuum pump are arranged within the crankcase.

[0023] The control electronics are used to activate and deactivate the vacuum pump and, if necessary, to regulate the pressure level of the vacuum generated by the vacuum pump. The pressure level is preferably regulated by regulating the pressure level of the vacuum pump. For this purpose, the control electronics are preferably connected to the electronics of the motor vehicle. The control electronics are preferably configured to actively respond to an operating state of the motor vehicle. This can mean, in particular, that increased vacuum can be provided during heavy braking of the motor vehicle, thus achieving increased brake force boost.

[0024] By locating the control electronics within the crankcase, and especially directly adjacent to the electric vacuum pump, short electrical connections can be achieved. Furthermore, the (oil-tight) crankcase does not need to be penetrated for a cable opening. This can prevent oil leaks and is also cost-effective.

[0025] In a further embodiment of the described internal combustion engine, the control electronics are designed to be temperature-resistant for temperatures up to 150°C, and for a short time to be temperature-resistant for temperatures up to 160°C.

[0026] If the control electronics are located within the crankcase, it may not be possible to avoid exposure to elevated temperatures that inevitably arise during operation of the internal combustion engine. Particularly if the control electronics are located in the oil sump together with the vacuum pump, the control electronics may be exposed to elevated oil temperatures during operation of the internal combustion engine. Preferably, the control electronics are even suitable for exposure to temperatures of up to 170°C without sustaining damage.

[0027] The temperature resistance of the control electronics can be achieved by using appropriately temperature-resistant materials for the control electronics or by thermally insulating temperature-sensitive materials. While the control electronics are temperature-resistant as described, the temperature specifications refer to the temperatures in the environment surrounding the control electronics. The temperature resistance of components inside the control electronics may be lower, especially if thermal insulation is present.

[0028] In a further embodiment of the described internal combustion engine, the cable connection comprises at least one plug connection.

[0029] This plug connection is typically designed to be detachable. The ability to separate the cable connection through the plug connection makes installation and removal of the electric vacuum pump easier. The plug connection is preferably a detachable connection. This also facilitates the removal or disassembly of the crankcase and / or oil pan. This is especially true because the cable connection can prevent the crankcase or oil pan from being connected to other components of the vehicle.

[0030] In a further embodiment of the described internal combustion engine, the plug connection is arranged at the opening of the crankcase.

[0031] According to this embodiment, the installation and removal of the electric vacuum pump can be further simplified. Preferably, the plug connection is designed such that the control electronics can be plugged directly into the plug connection and the crankcase. This means, for example, that a plug of the plug connection is recessed into the wall of the crankcase. The control electronics can be connected to the plug connection on the outside (facing outwards) of the wall. The vacuum pump can be connected to the plug connection on the inside (facing inwards, towards the oil) of the wall.

[0032] In a further embodiment of the described internal combustion engine, the control electronics are arranged on the outside of the crankcase.

[0033] In this embodiment, the control electronics are not only located outside at any location within a motor vehicle, but directly on the outer wall of the crankcase. This embodiment enables a compact design of the internal combustion engine and shortens the required cable length.

[0034] It is particularly preferred if the control electronics are located on the underside of the crankcase. This position of the control electronics, located outside the crankcase, enables a particularly compact design. As indicated above, the vacuum pump itself is preferably located in the lower area of ​​the crankcase. The required length of the cable connection is further reduced by the position of the control electronics on the underside, allowing for a particularly short cable connection.

[0035] A short cable connection can help to significantly reduce electromagnetic interference, which can always emanate from a cable connection.

[0036] In a further embodiment of the described internal combustion engine, the control electronics are thermally insulated from the crankcase by thermal insulation.

[0037] In a further embodiment of the described internal combustion engine, the cable connection has a magnetic shield.

[0038] In addition to or as an alternative to the previously described advantage of keeping the cable connection as short as possible, the generation or propagation of electromagnetic interference signals within the internal combustion engine or in the vicinity of the internal combustion engine can be reduced by magnetic shielding. The magnetic shield is preferably a sheath made of a material suitable for shielding electromagnetic interference signals. The magnetic shield preferably encloses the entire length of the cable connection.

[0039] Preferably, the magnetic shielding is integrated into the plug connection. Preferably, the cable connection is designed so short that only the plug connection requires magnetic shielding. The cable connection is then not formed by a conventional (possibly flexible) cable element, but rather there is only the plug connection that forms the cable connection. The plug connection then has a connector in the crankcase for connecting the vacuum pump. The plug connection then has a connector outside the crankcase for connecting the control electronics. The plug connection can even be integrated into the crankcase or the oil pan.

[0040] The invention is preferably used in a motor vehicle having an internal combustion engine and at least one braking system which is connected to the electric vacuum pump in such a way that a vacuum generated by the electric vacuum pump can be used by the braking system.

[0041] The braking system preferably comprises at least one brake cylinder and other elements required to decelerate the motor vehicle, such as brake discs. It is preferred that the braking system includes at least one brake booster. This can be, for example, a so-called Mastervac.

[0042] A particularly advantageous brake booster has a chamber divided into two parts by a diaphragm. When the brake pedal is released, both parts of the chamber are connected by a connecting valve and maintained at a vacuum generated by the electric vacuum pump. When the brake pedal is depressed, an external valve on the pedal-side part of the chamber opens and the connecting valve closes. By adjusting the atmospheric pressure in the pedal-side part of the chamber, a force is exerted on the diaphragm, directed away from the brake pedal. A brake piston, which is connected to both the brake pedal and the diaphragm, then transfers both the force exerted via the brake pedal and the additional force acting on the diaphragm to the brake cylinder connected to the brake piston.

[0043] When the motor vehicle is in operation, the electric vacuum pump is preferably operated at a power level regulated by the control electronics depending on the operating state of the motor vehicle. In a fast-moving motor vehicle, the need for high-force braking is more likely than in a slow-moving or stationary motor vehicle. Therefore, the vacuum level generated by the electric vacuum pump is preferably adjusted, in particular, depending on the speed of the motor vehicle.

[0044] The invention and the technical environment are explained in more detail below with reference to the figures. The figures show particularly preferred embodiments, to which the invention is not limited, however. It should be noted that the invention and, in particular, the proportions shown are only schematic. They show: Fig. 1: a schematic representation of an internal combustion engine with control electronics arranged outside the crankcase in a lower area of ​​an oil pan, Fig. 2: a schematic representation of an internal combustion engine with control electronics arranged within the oil pan, Fig. 3: a schematic representation of an internal combustion engine with control electronics arranged outside the crankcase.

[0045] Fig. 1 shows a motor vehicle 1 with an internal combustion engine 2 and a braking system 3. The braking system 3 has a brake booster 16. The internal combustion engine 2 has a crankcase 4 with a crankshaft 5 held therein. On an underside 7, the crankcase 4 has an oil pan 6. An electric vacuum pump 10 is arranged within the oil pan 6. The electric vacuum pump 10 is connected to the brake booster 16 via a compressed air connection 17. The electric vacuum pump 10 also has an air supply 20, indicated schematically here, via which air can be sucked in, which is provided as compressed air via the compressed air connection 17. Oil 8 is held within the oil pan 6 and fills the oil pan 6 up to a fill level 9. A cable connection 13 is connected to the electric vacuum pump 10. The cable connection 13 has a length of 18.The cable connection 13 has a plug connection 14, which is arranged at an opening 15 of the oil pan 6 on the underside 7. A control electronics unit 12 is connected to the electric vacuum pump 10 via the cable connection 13. A thermal insulation unit 11 is arranged between the control electronics unit 12 and the underside 7 of the oil pan 6. Furthermore, a fluidic insulation unit 21 is provided there, which prevents oil 8 from escaping from the oil pan 6.

[0046] The Fig. The embodiment shown in Figure 2 differs from that shown in Fig. 1 shown in particular by the position of the control electronics 12. All elements not mentioned below are identical to those in Fig. 1. Reference is made to the description of Fig. 1. In this embodiment, the control electronics 12 is arranged within the crankcase 4 within the oil pan 6 and contacts the electric vacuum pump 10. To connect the control electronics 12 according to Fig. 2 with the environment, there may be an electrical connection 22. This electrical connection 22 may also be guided through the oil pan 6 with a thermal insulation (not shown here) and a fluidic insulation 21 (not shown here), which is connected to the Fig. 1. The electrical connection 22 serves, for example, to supply power to the vacuum pump 10 and / or to signal the vacuum pump 10 from a connected control unit (not shown).

[0047] In Fig. 3 shows a further embodiment, whereby the position of the control electronics 12 differs from the previously shown embodiments. Reference is also made here to the description of the Fig. 1. In this embodiment, the control electronics 12 are arranged on the outside of the crankcase 4, but in this case not as before on the underside 7 of the oil pan 6, but in an upper region of the crankcase 4. In addition, a magnetic shield 19 is shown in this embodiment. This is designed to prevent electromagnetic interference signals that may emanate from the cable connection 13. In the area where the cable connection 13 passes through the oil pan 6 or the wall of the oil pan 6, thermal insulation (not shown here) and fluidic insulation (not shown here) may also be provided. List of reference symbols 1 motor vehicle 2 internal combustion engine 3 Braking system 4 crankcase 5 Crankshaft 6 Oil pan 7 Bottom 8 Oil 9 Filling level 10 electric vacuum pump 11 thermal insulation 12 Control electronics 13 Cable connection 14 Plug connection 15 Cable opening 16 brake booster 17 Compressed air connection 18 length 19 magnetic shielding 20 Air supply 21 Fluidic Isolation 22 Electrical connection

Claims

[1] Internal combustion engine (2) comprising at least one crankcase (4) with an oil pan (6) and an electric vacuum pump (10), wherein the electric vacuum pump (10) is arranged within the crankcase (4), and wherein the electric vacuum pump (10) is designed such that the electric vacuum pump (10) can be lubricated with oil (8) held in the oil pan (6), characterized by in that control electronics (12) for the electric vacuum pump (10) are arranged outside the crankcase (4), wherein the control electronics (12) and the electric vacuum pump (10) are connected via a cable connection (13), wherein the cable connection (13) is guided through an opening (15) of the crankcase (4), and wherein the opening (15) is sealed for oil. [2] Internal combustion engine (2) according to claim 1, wherein control electronics (12) for the electric vacuum pump (10) are arranged within the crankcase (4). [3] Internal combustion engine (2) according to claim 2, wherein the control electronics (12) are designed to be temperature-resistant for temperatures up to 150 °C. [4] Internal combustion engine (2) according to one of the preceding claims, wherein the cable connection (13) comprises at least one plug connection (14). [5] Internal combustion engine (2) according to claim 4, wherein the plug connection (14) is arranged at the opening (15) of the crankcase (4). [6] Internal combustion engine (2) according to one of the preceding claims, wherein the control electronics (12) are arranged on the outside of the crankcase (4). [7] Internal combustion engine (2) according to one of the preceding claims, wherein the control electronics (12) is thermally insulated from the crankcase (4) by means of a thermal insulation (11). [8] Internal combustion engine (2) according to one of the preceding claims, wherein the cable connection (13) has a magnetic shield (19). [9] Motor vehicle (1) comprising an internal combustion engine (2) according to one of the preceding claims and at least one braking system (3) which is connected to the electric vacuum pump (10) in such a way that a vacuum generated by the electric vacuum pump (10) can be used by the braking system (3).

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