DE102022108568A1 - Internal combustion engine with a heatable actuating device for a displaceable cam carrier - Google Patents

Abstract

An internal combustion engine comprises at least one combustion chamber to which at least one gas exchange valve is assigned, a camshaft for actuating the gas exchange valve, the camshaft comprising a basic shaft and a cam carrier 25 which can be moved axially on the basic shaft, and an actuating device 27 for displacing the cam carrier 25 as needed by means of at least one actuator acting on the cam carrier 25. Furthermore, means for heating the actuator are also provided.

Description

The invention relates to an internal combustion engine with at least one combustion chamber, to which at least one gas exchange valve is assigned, with a camshaft for actuating the gas exchange valve, the camshaft comprising a basic shaft and a cam carrier which can be moved axially on the basic shaft, and with an actuating device for displacing the cam carrier if necessary at least one actuator acting on the cam carrier.

The displacement of the cam carrier can serve to bring one of several different cams into operative connection with the gas exchange valve in order to influence its actuation.

A corresponding combustion engine is available in each case DE 10 2018 107 936 A1 , the US 2020/0165946 A1 and the DE 10 2018 102 382 A1 disclosed.

The invention is based on the object of improving such an internal combustion engine with regard to the function of the actuating device or the variability that can be achieved by it with regard to the actuation of the gas exchange valve.

This task is solved in an internal combustion engine according to claim 1. Advantageous embodiments of this are the subject of the further patent claims and/or result from the following description of the invention.

An internal combustion engine according to the invention comprises at least one combustion chamber, to which at least one gas exchange valve is assigned, a camshaft for actuating the gas exchange valve during running operation of the internal combustion engine, wherein the camshaft has a fundamental shaft and an axially (i.e. along the longitudinal or rotational axis of the fundamental shaft) displaceable on the fundamental shaft Cam carrier includes, and an actuating device for moving the cam carrier as needed by means of at least one actuator acting on the cam carrier (device that converts an electrical signal into a mechanical movement). According to the invention, means for heating the actuator are also provided. This makes it possible to heat the actuator if necessary in order to ensure the functional reliability of the actuator even at relatively low ambient temperatures. Low ambient temperatures, if they lead to correspondingly low body temperatures of the actuator, can reduce the performance of the actuator and in particular the speed at which it can act on the cam carrier to move it. This can result in the cam carrier not being able to be completely moved within a defined period of time intended for this purpose. As a result, use of the actuating device and thus the realization of a change in the actuation of the gas exchange valve can be temporarily prevented. This can be the case in particular after a so-called cold start of the internal combustion engine, in which this and thus also the actuator of the actuating device can have a temperature essentially corresponding to the ambient temperature, because then the actuator must first be heated by waste heat from the internal combustion engine, the internal combustion engine After a cold start, waste heat is released with a delay. Due to the inventive design of an internal combustion engine, the actuator of the actuating device can be temperature-controlled independently of waste heat from the internal combustion engine and thus its functionality can be guaranteed. In particular, it is possible to use the actuating device immediately or relatively briefly after a cold start of the internal combustion engine and thus to change the actuation of the gas exchange valve as necessary.

Preferably, it can be provided that a plurality of gas exchange valves, in particular at least one inlet valve and one outlet valve, are assigned to the at least one combustion chamber of an internal combustion engine according to the invention. An internal combustion engine according to the invention can also preferably have several combustion chambers, each of which is assigned at least one gas exchange valve, preferably several gas exchange valves. Furthermore, an internal combustion engine according to the invention can comprise several and in particular two camshafts. It can be provided that one, several or all of the camshafts have a displaceable cam carrier or several displaceable cam carriers and one or more actuating devices assigned to them are provided. If there are several actuating devices, one, several or all of them can, according to the invention, be equipped with means for heating the associated actuator or several associated actuators.

According to one embodiment of an internal combustion engine according to the invention, it can be provided that the means for heating comprise or are a heating device, whereby a heating device is understood to be a device which is primarily or exclusively intended to release thermal energy in a controlled manner as required. Such a heating device can in particular be designed electrically and therefore on a Conversion of electrical energy into thermal energy. Such an electrical heating device can in particular be designed as a resistance heating device, with alternative configurations for the (electrical) heating device (eg in the form of a piezo heating device or PTC heating device) being advantageously provided.

According to a preferred embodiment of an internal combustion engine according to the invention, it can be provided that the actuator is designed to act electromagnetically. Such an electromagnetic actuator can have a coil which, if necessary and specifically, can be supplied with electrical voltage by means of a control device of the internal combustion engine, whereby a current flow is then generated through the coil, which generates a directed magnetic field which causes a movement of an actuating element of the actuator can preferably be designed as an anchor partially guided within the coil.

If such an internal combustion engine according to the invention has a heating device which is designed in such a way, for example by comprising a heating coil, that a magnetic field is generated during its (heating) operation, it can preferably be provided that this magnetic field is directed in such a way when the heating device is used that this does not cause the cam carrier to move or that this does not cause the actuator to be actuated. At the same time, it can be provided that the heating device generates a magnetic field in an additional (support) operation, which specifically supports a movement of the actuating element of the actuator, which leads to a displacement of the cam carrier.

In an internal combustion engine according to the invention with an electromagnetic actuator, the electrical coil of the actuator can also be advantageously used as a means for heating. It can preferably be provided that the coil is energized in such a way that no displacement of the cam carrier is realized because the energization of the coil should serve exclusively for the purpose of heating and not a change in the actuation of the gas exchange valve. For this purpose, an internal combustion engine according to the invention can have a control device set up accordingly for controlling the coil of the actuator.

According to a preferred embodiment of an internal combustion engine according to the invention, it can be provided that the actuator comprises a guide pin which, if necessary, can be brought into engagement with a guide groove of the cam carrier in order to realize a displacement of the cam carrier. This guide pin can in particular be part of an actuating element of an electromagnetically designed actuator. Such a design of an internal combustion engine according to the invention enables variability with regard to the actuation of the gas exchange valve, which is structurally relatively simple and at the same time functionally reliable.

If, in such an internal combustion engine according to the invention, no displacement of the cam carrier is to be realized when the coil is used as a means for heating the actuator, it can be provided, on the one hand, that the coil is energized in such a way that the guide pin does not engage in the guide groove. Rather, the current supply to the coil can be selected such that the guide pin is pressed against a stop as a result of the magnetic field generated by the current supply to the coil, with the guide pin not engaging in the guide groove. If necessary, this requires a design of the actuating device and/or the control device such that the energization of the coil can be changed with regard to the current flow and thus the direction of the magnetic field, because energization may be required for the use of the actuator to move the cam carrier, which requires an intervention of the guide pin into the guide groove. With such an inventive design of an internal combustion engine, a relatively complex design of the actuating device and/or the control device may be required.

This disadvantage can be avoided if, alternatively or additionally, it is provided that the coil is energized when the internal combustion engine is at a standstill in such a way that the guide pin engages in the guide groove and/or presses against the cam carrier. The energization of the coil of the actuator can therefore take place in the same way as is provided for a displacement of the cam carrier and a resulting change in the actuation of the gas exchange valve during running operation of the internal combustion engine. However, the standstill of the internal combustion engine prevents the cam carrier from moving.

According to a preferred embodiment of an internal combustion engine according to the invention, it can be provided that the actuating device has a first actuator and a second actuator, each of which includes a guide pin, which can be brought into engagement with one or the guide groove if necessary, with engagement of the guide pin of the first actuator Moving the cam carrier into a first position and engagement of the guide pin of the second actuator causes the cam carrier to move into a second position. Wei Further preferably, the actuators can each comprise a coil.

If in such an internal combustion engine according to the invention it is provided that when at least one of the coils is used as a means for heating, the corresponding coil is energized in such a way that the associated guide pin does not engage in the guide groove, it can be provided that the coils of both actuators are at least temporarily simultaneously be energized, whereby the highest possible heating output can be achieved for the entire actuating device. Alternatively, it can be provided that the coil is energized exclusively by that actuator whose guide pin can immediately cause the cam carrier to move by engaging in the associated guide groove as a result of a corresponding position of the cam carrier. Accordingly, provision can be made to heat only the actuator that is then used to move the cam carrier. This can be implemented particularly advantageously if, in the case of actually cold actuators, such as may be the case in particular after a cold start of the internal combustion engine, a specific displacement of the cam carrier and thus the use of a specific actuator is always provided first. If the other actuator is intended to be used, it may then be warmed up to such an extent by waste heat resulting from the heating of the actuator used first or from the running operation of the internal combustion engine that this other actuator, or actuator used only second, may not be designed to be heatable itself have to be. This can have an advantageous effect with regard to the design complexity of a corresponding internal combustion engine according to the invention.

If, on the other hand, in such an internal combustion engine according to the invention with a first actuator and a second actuator it is provided that the guide pin of at least one of the actuators engages in the guide groove and/or presses against the cam carrier when the internal combustion engine is at a standstill, it can preferably be provided that only the coil of the first Actuator is energized, through which the cam carrier can be moved into the first position, the first position being provided as the starting position for starting up the internal combustion engine. In this way, despite the guide pin being extended, it can be avoided that the cam carrier is moved when the internal combustion engine is started up into a position that is not intended for the running operation of the internal combustion engine immediately following such start-up.

An internal combustion engine according to the invention can be a (self-igniting and quality-controlled) diesel engine or a (spark-ignited and quantity-controlled) gasoline engine or a combination thereof, i.e., for example, an internal combustion engine with homogeneous compression ignition. The internal combustion engine can be operated with liquid fuel (i.e. diesel or gasoline) and/or with a gaseous fuel (in particular natural gas, LNG or LPG).

The invention also relates to a motor vehicle, in particular a wheel-based and non-rail-bound motor vehicle (preferably a car or a LKVη, with an internal combustion engine according to the invention. The internal combustion engine can be provided in particular for (directly or indirectly) providing the traction power for the motor vehicle.

• 1: einen erfindungsgemäßen Verbrennungsmotor in einer Aufsicht;
• 2: den Verbrennungsmotor in einem Längsschnitt;
• 3: einen Nockenträger des Verbrennungsmotors sowie eine dazugehörige Betätigungsvorrichtung;
• 4: eine Abwicklung von Führungsnuten des Nockenträgers und ein Tiefenprofil der Führungsnuten;
• 5: einen Querschnitt durch die Betätigungsvorrichtung gemäß einer ersten Ausgestaltungsform;
• 6: einen Querschnitt durch die Betätigungsvorrichtung gemäß einer zweiten Ausgestaltungsform; und
• 7: einen Querschnitt durch die Betätigungsvorrichtung gemäß einer dritten Ausgestaltungsform.

The invention is explained in more detail below using design examples shown in the drawings. The drawings show, each in a simplified representation:

• 1 : a top view of an internal combustion engine according to the invention;
• 2 : the internal combustion engine in a longitudinal section;
• 3 : a cam carrier of the internal combustion engine and an associated actuating device;
• 4 : a development of guide grooves of the cam carrier and a depth profile of the guide grooves;
• 5 : a cross section through the actuating device according to a first embodiment;
• 6 : a cross section through the actuating device according to a second embodiment; and
• 7 : a cross section through the actuating device according to a third embodiment.

In the 2 and 3 an internal combustion engine 1 according to the invention of an internal combustion engine is shown. This forms several (eg four) cylinder openings 4 in a composite of cylinder housing 2 and cylinder head 3. The cylinder openings 4 are connected in a gas-carrying manner on the inlet side to an intake pipe 6 of a fresh gas line 5 and on the outlet side to an exhaust manifold 8 of an exhaust line 7 of the internal combustion engine 1. In a known manner, the combustion chambers 9 are limited by the cylinder openings 4 together with the pistons 10 guided therein and by the cylinder head 3 are, fresh gas (exclusively or mainly air) burned with fuel. For this purpose, the fuel can be introduced directly into the combustion chambers 9 using injectors 11. The exhaust gas resulting from the combustion of the fuel-fresh gas mixtures is discharged via the exhaust system 7.

The supply of fresh gas into the combustion chambers 9 and the removal of the exhaust gas from the combustion chambers 9 is controlled via gas exchange valves 12, in the present exemplary embodiment via two inlet valves 12a and two outlet valves 12b per combustion chamber 9, which are controlled by one in the 1 not in the 2 only partially and in the 3 Valve train of the internal combustion engine 1 shown in further details can be actuated.

The valve train includes according to the 2 a crankshaft 13 which forms crank pins 14, the crank pins 14 being connected to the pistons 10 via connecting rods 15. As a result, linear movements of the pistons 10 lead to a rotation of the crankshaft 13, the rotation of the crankshaft 13 in turn causing a periodic change in direction of the linear movements of the pistons 10. A rotation of the crankshaft 13 is also transmitted via a control gear, for example a toothed belt gear 16, to two camshafts 17, each of which actuates two gas exchange valves 12 for each combustion chamber 9. One of the camshafts 17 is designed as an intake camshaft, ie it operates all intake valves 12a, while the other is designed as an exhaust camshaft and consequently operates all exhaust valves 12b.

The internal combustion engine also includes an exhaust gas turbocharger (cf. 1 ). This has an exhaust gas turbine 18 integrated into the exhaust gas line 7 and a fresh gas compressor 19 integrated into the fresh gas line 5. An impeller of the exhaust gas turbine 18, which is driven to rotate by an exhaust gas flow, drives an impeller of the fresh gas compressor 19 via a shaft 20. The rotation of the impeller of the fresh gas compressor 19 caused in this way compresses the fresh gas passed through it. By means of a wastegate 21, a boost pressure limitation can be achieved by guiding part of the exhaust gas flow past the exhaust gas turbine 18 when the internal combustion engine 1 is operating at high speeds and/or loads. Furthermore, an exhaust gas aftertreatment device 22 is integrated into the exhaust system 7.

The internal combustion engine 1 further comprises an adjusting device 23, by means of which the gas exchange valves 12 can be switched from actuation according to a first valve lift curve to actuation according to a second valve lift curve. This adjusting device 23 can be controlled by a control device 24 and in the 2 only indicated schematically. The function of the adjusting device 23 is based on the longitudinal axial displaceability of sleeve-shaped cam carriers 25 (see also 3 ), which are arranged in a rotationally fixed manner on a base shaft 26 of the respective camshaft 17, by means of an actuating device 27 (cf. 3 ). The cam carriers 25 have two different cams 28, 29 for each of the gas exchange valves 12 that can be actuated by them (cf. 3 ), which, depending on the set displacement positions of the cam carriers 25, alternatively interact with the associated gas exchange valves 12.

In the embodiment example, as shown in the 1 until 3 is shown, each of the cam carriers 25 comprises a total of four pairs of first and second cams, 28, 29, each of which is assigned to a gas exchange valve 12 of the internal combustion engine 1. By means of the cams 28, 29, which are formed by such a cam carrier 68, either the inlet valves 12a or the outlet valves 12b of a total of two adjacent combustion chambers 9 of the internal combustion engine 1, in which each combustion chamber 9 is assigned two inlet valves 12a and two outlet valves 12b , pressed. Between the two pairs of cams assigned to the gas exchange valves 12 of a first combustion chamber 9 and the two pairs of cams assigned to the gas exchange valves 12 of a second combustion chamber 9, each of the cam carriers 25 forms according to 3 There is also a switching gate with two guide grooves 30. Through an interaction of these guide grooves 30 with guide pins 31 of the associated actuating device 27, the associated cam carrier 25 can be axially displaced by a defined distance and thereby (exclusively) a selected one of the cams 28, 29 of each cam pair can be brought into operative connection with the associated gas exchange valve 12. According to the 3 For this purpose, for example, starting from the position shown in which the gas exchange valves 12 are each in operative connection with the right cam 28 of each pair of cams, the left guide pin can be extended and the cam carrier 25 can thereby be moved to the right in cooperation with a rotation. As a result of the guide grooves 30 running out into the outer circumference of the shift gate, the left guide pin 31 is then moved back into the retracted position. After such a displacement of the cam carrier 25, the left cams 29 of each pair of cams are then in operative connection with the associated gas exchange valve 12. Such a displacement of one of the cam carriers 25 to the right also leads to the right guide pin 31 overlapping with the right guide groove 30 was brought so that by extending this right guide pin 31 the cam carrier 25 is moved the same distance can be moved to the left.

In the 4 the guide grooves 30 of the cam carriers 25 are shown in an unrolled form. In addition, a depth profile of these guide grooves 30 is shown. Accordingly, each of the guide grooves 30 has a circumferentially extending engagement area 32 with varying groove depth for engaging the associated guide pin 31, an adjustment area 33 adjoining it in the circumferential direction with an axial course component for moving the cam carrier 25, and a braking area 34 adjoining it in the circumferential direction for braking the axial movement component of the cam carrier 25 to the end of the axial displacement and an ejection area 35 adjoining it in the circumferential direction with an ejection ramp for moving the guide pin 31 back.

The actuating devices 27 include according to 5 until 7 two electromagnetic actuators 36 each, which are arranged within a housing 37 of the actuating device 27 and which each comprise an electrical coil 38, which can be supplied with electrical voltage if necessary by the control device 24 and can therefore be energized, and an armature 39. The armature 39 has an axially movably guided armature piston 40 within the coil 38 or one within a guide tube 44 which is arranged within the coil 38, at one end of which an armature plate 41 with a permanent magnet is attached. An associated guide pin 31 of the actuator 36 is held magnetically on the anchor plate 41 with one of its ends.

Energizing the coil 38 of an actuator 36 leads to the generation of a magnetic field which, in interaction with the permanent magnet of the armature 39, causes the armature piston 40 to move out of the coil 38 and thus extends the associated guide pin 31, as shown in FIG 5 until 7 each is shown for the right of the actuators 36.

If the current supply to the coil 38 is ended, the guide pin 31 is moved back when the associated cam carrier 25 rotates as it passes through the ejection area 35 and is held magnetically in the retracted position due to the effect of the permanent magnet of the armature plate 41.

According to the invention, means for heating at least one of the actuators 36 of each actuating device 27 are provided.

In the actuating device 27 according to 5 the electrical coils 38 of the actuators 36 can be used as a means for heating.

For this purpose, it can be provided that by changing the direction of the current flow through the coils 38 compared to the direction that is intended for extending the guide pins 31, the coils 38 can be energized as required without this causing the guide pins 31 to be extended leads. Rather, a magnetic field is generated that presses the armature 39 and the guide pin 31 held thereon into the retracted position. Due to resistance losses, the energization ensures that the coils 38 and thus the entire actuators 36 are heated. Such heating of the actuators 36 is possible both when the internal combustion engine 1 is at a standstill and while it is running, because the armature 39 and the on it held guide pin 31 are pressed into the retracted position, no unwanted displacement of the cam carrier 25 can occur as a result of energization of the coils 38 of the actuators 36 intended for heating.

Furthermore, it can be provided that the coil 38 of one of the actuators 36 of each actuating device 27 according to 5 When the internal combustion engine 1 is at a standstill, current is energized to heat this actuator 36 in such a way that the guide pin 31 engages in the associated guide groove 30 of the cam carrier 25 or would intervene in the event of a partial rotation of the cam carrier 25. The 4 shows with cross hatching the area of the cam carrier 25 in which the extended guide pin 31 can come into contact with the cam carrier 25. In this case, the coil 38 of the actuator 36 is energized, the use of which would lead to a position of the cam carrier 25 when the internal combustion engine 1 is running, which is also intended for a standstill of the internal combustion engine 1 or was implemented for the standstill.

In the actuating devices 27 according to 6 and 7 A heating device 42 is integrated into the actuating devices 27. The heating device 42 of the actuating device according to the 6 has a single coil-shaped resistance heating element 43, which surrounds both actuators in the area of the associated coils 38. The heating device 42 of the actuating device according to the 7 On the other hand, each actuator 26 has a coil-shaped resistance heating element 43. Instead of an arrangement of the heating element 43 surrounding the coil 38 of the individual actuators 36, they can also be integrated into the guide tubes 44 of the actuators 36. The heating elements 43 can, if necessary, be controlled by the control device 24, are supplied with electrical voltage, in which case a current flow through the respective resistance heating element 43 leads to a conversion of electrical energy into thermal energy, which causes the respective actuator 36 to be heated.

REFERENCE SYMBOL LIST

1

Internal combustion engine

2

Cylinder housing

3

cylinder head

4

Cylinder opening

5

Fresh gas line

6

Suction pipe

7

Exhaust system

8th

exhaust manifold

9

combustion chamber

10

Pistons

11

injector

12

Gas exchange valve

12a

Inlet valve

12b

outlet valve

13

crankshaft

14

Crank pin

15

connecting rod

16

Timing belt transmission

17

camshaft

18

exhaust turbine

19

Fresh gas compressor

20

Wave

21

Wastegate

22

Exhaust gas aftertreatment device

23

Adjusting device

24

Control device

25

Cam carrier

26

fundamental wave

27

Actuating device

28

first cam

29

second cam

30

Guide groove

31

Guide pin

32

Tracking area of the guide groove

33

Adjustment range of the guide groove

34

Braking area of the guide groove

35

Ejection area of the guide groove

36

Actor

37

Actuator housing

38

Actuator coil

39

Actuator anchor

40

anchor piston

41

anchor plate

42

Heating device

43

Heating element of the heater

44

Actuator guide tube

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102018107936 A1 [0003]
• US 2020/0165946 A1 [0003]
• DE 102018102382 A1 [0003]

Claims (10)

Internal combustion engine (1) with • at least one combustion chamber (9), to which at least one gas exchange valve (12) is assigned, • a camshaft (17) for actuating the gas exchange valve (12), the camshaft (17) having a basic shaft (26) and a axially displaceable on the base shaft (26) cam carrier (25), and • an actuating device (27) for displacing the cam carrier (25) if necessary by means of at least one actuator (36) acting on the cam carrier (25), characterized by means for heating the Actuator (36). Internal combustion engine (1) according to Claim 1 , characterized in that the means for heating comprise or are a heating device (42). Internal combustion engine (1) according to Claim 1 or 2 , characterized in that the actuator (36) is designed to act electromagnetically, an electrical coil (38) of the actuator (36) being usable as a means for heating. Internal combustion engine (1) according to Claim 3 , characterized by a control device (24) which is designed to energize the coil (38) to use the coil (38) as a means for heating in such a way that the cam carrier (25) is not displaced. Internal combustion engine (1) according to one of the preceding claims, characterized in that the actuator (36) comprises a guide pin (31) which, if necessary, can be brought into engagement with a guide groove (30) of the cam carrier (25) in order to displace the cam carrier ( 25) to realize. Internal combustion engine (1) according to Claim 4 and 5 , characterized in that the coil (28) is energized in such a way that the guide pin (31) does not engage in the guide groove (30). Internal combustion engine (1) according to Claim 4 and 5 , characterized in that the coil (28) is energized when the internal combustion engine (1) is at a standstill in such a way that the guide pin (31) engages in the guide groove (30) and / or presses against the cam carrier (25). Internal combustion engine (1) according to one of Claims 5 until 7 , characterized in that the actuating device (27) has a first actuator (36) and a second actuator (36), each of which comprises a guide pin (31) which, if necessary, can be brought into engagement with one or the guide groove (30), wherein a Engagement of the guide pin (31) of the first actuator (36) causes the cam carrier (25) to move into a first position and engagement of the guide pin (31) of the second actuator (36) causes the cam carrier (25) to move into a second position. Internal combustion engine (1) according to Claim 6 and 8th , characterized in that the actuators (36) each comprise a coil (38), the coils (38) being energized at least temporarily at the same time or the coil (38) being energized exclusively by that actuator (36) whose guide pin (31) passes through an engagement in the associated guide groove (30) can immediately cause the cam carrier (25) to move. Internal combustion engine (1) according to Claim 7 and 8th , characterized in that the actuators (36) each comprise a coil (38), with only the coil (38) of the first actuator (36) being energized and the first position being provided as the starting position for starting up the internal combustion engine (1). .

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