Method for determining a cam piece position of a valve train for an internal combustion engine, and valve train

Abstract

The invention relates to a method for determining the position of at least one cam piece (20L, 20R) of a valve train for an internal combustion engine. The invention also relates to a valve train for carrying out the method.

Description

[0001] Description

[0002] Method for detecting a cam piece position of a valve train for an internal combustion engine and valve train

[0003] The invention relates to a method for detecting a cam piece position of a valve train for an internal combustion engine and a valve train.

[0004] The technological background of the invention is considered to be the documents DE 102009 006632 B4, DE 102011 001 125 A1, DE 102011 011 455 A1, DE 102016 119680 B4 and DE 10 2018 115 535 A1.

[0005] The document DE 102008 049 103 A1 discloses a sensor installed in the sliding cam actuator that detects pole wheels arranged on the sliding cams.

[0006] The document WO 2020 / 182400 A1 describes the detection of the position of the sliding cam pieces via an active Hall sensor, which directly senses the switching gate of a sliding cam piece.

[0007] The document WO 2013 / 182300 A1 discloses a method in which an actuation signal is generated by integrating the induced voltage during the reflection.

[0008] Finally, the patent DE 102015 013 075 B4 describes a further method for checking a valve train of an internal combustion engine when the engine is at a standstill.

[0009] The applicants possess a groundbreaking new technology that enables an internal combustion engine to be operated with so-called "active cylinder management." This active cylinder management is used, for example, in an internal combustion engine, in particular a four-cylinder TSI engine (TSI = Twincharged or Turbocharged Stratified Injection). This cylinder management enables the user to experience dynamic driving pleasure and advantageously results in lower fuel consumption. Depending on the engine's power requirements, two cylinders are deactivated or activated, for example. Cylinder deactivation is only used, for example, in the speed range from 1,400 to 4,000 rpm and in the load range from 25 to 75 Nm. It advantageously leads to an average reduction in standard fuel consumption of 0.4 l per 100 km.Externally, the engine with cylinder deactivation differs from a base engine of the same power output by virtue of the actuators mounted on the cylinder head cover. Two camshafts, each assigned to two cylinders, are operated via the timing belt and the phase adjuster. The camshafts have external splines. Mounted on the splines are so-called cam lobes, which also have internal splines. The toothing of the components allows for axial displacement of the cam lobes of, for example, cylinders two and three on the intake and exhaust sides. There are two cam contours per valve, one of which has a continuous base circle. The cam contour is transmitted to the valve via a roller rocker arm. The displacement mechanism is activated by a double actuator per cam lobe.With a switching time of, for example, 11 ms, a pin, i.e., an actuator of the dual actuator, engages a worm gear of the switching gate, which is connected to the cam piece. The cam piece is moved from full lift to zero lift in the base circle phase. The valves and thus the combustion chambers remain closed. Fuel injection in cylinders two and three is simultaneously deactivated, and they continue to run without firing. Cylinder deactivation is now active. According to the exemplary embodiment, cylinders one and four are now operated in a higher load range via the other cam contour, which does not have the continuous base circle. Lower gas exchange losses and thus an overall higher engine efficiency ensure up to 20% lower fuel consumption during partial load operation in city traffic, on country roads, or when driving on the highway up to 130 km / h.When the load on the engine increases, for example during acceleration phases, the idle cylinders are switched on again in the same way within one and a half camshaft revolutions.

[0010] In a valve train featuring a sliding cam system, the engine control unit must therefore be provided with information about the current position of the axially movable cam lobe. Position detection of the cam lobe ensures functional engine operation and compliance with emissions limits.

[0011] As explained above, it is known that in such systems, an actuator pin, i.e., an actuator, controls the sliding direction of the cam piece. After the switching is complete, a return signal is generated. This allows the current position of the cam piece to be assigned. Multi-stage sliding cam systems or systems with a so-called XS sliding gate or switching gate have not yet had such a clear assignment, since one and the same actuator controls different directions or switching states. This requires a clear assignment of the position of the actuator in relation to the position of the cam piece, which is the object of the invention.

[0012] The starting point of the invention is a method for detecting the position of at least one cam piece of a valve train for an internal combustion engine, wherein the valve train has at least one camshaft on which at least one cam piece is arranged in a rotationally fixed manner and axially displaceable between at least two axial positions, on which at least one cam piece is formed with a predeterminable cam contour. It is further provided that an axial displacement of the at least one cam piece takes place by means of an actuator along the camshaft, wherein the at least one cam piece is assigned a switching gate designed as a groove, in which a first switching groove and a second switching groove are arranged, the groove depths of which differ from one another in an intersection region in which the switching grooves intersect in a spiral shape for the axial displacement of the at least one cam piece. The actuator is arranged in an installation position with respect to the at least one cam piece.which enables the at least one actuator to be reversibly extended from the actuator in the direction of the camshaft and retracted into the switching gate, wherein the axial displacement of the at least one cam piece is effected by initiating a control signal by energizing a coil unit arranged stationary in the actuator, which drives an armature assembly connected to the at least one actuator, whereupon the at least one actuator is extended from the actuator in the direction of the camshaft and positioned in the switching gate.

[0013] According to the invention, the detection of the position of the at least one actuator is carried out by at least one Hall sensor which is arranged in the actuator for detecting the position of the at least one actuator, wherein the Hall sensor provides a Hall sensor signal depending on the position of the at least one actuator, from which it is concluded whether the at least one actuator is retracted in the first switching groove or second switching groove of the at least one cam piece.

[0014] Preferred embodiments of the method are formulated in the subclaims, with the associated embodiments being explained in detail in the description. The invention further relates to a valve train for an internal combustion engine for implementing the method, wherein the valve train has at least one camshaft on which at least one cam piece is arranged in a rotationally fixed manner and axially displaceable between at least two axial positions, on which at least one cam with a predeterminable cam contour is formed.It is further provided that the at least one cam piece is assigned, by means of an actuator along the camshaft, a switching gate designed as a groove, in which a first switching groove and a second switching groove are arranged, the groove depths of which differ from one another in an intersection region in which the switching grooves cross in a spiral for the axial displacement of the at least one cam piece, wherein the actuator is arranged in an installation position with respect to the at least one cam piece which enables the at least one actuator to be reversibly extended from the actuator in the direction of the camshaft and retracted into the switching gate, wherein a stationary coil unit is arranged in the actuator, which drives an armature assembly which is connected to the at least one actuator, is arranged in the actuator and is movable relative to the coil unit.

[0015] According to the invention, at least one Hall sensor is arranged in the actuator for detecting the position of the at least one actuator, which provides a Hall sensor signal depending on the position of the at least one actuator.

[0016] Preferred embodiments of the valve train are formulated in the subclaims, wherein the associated embodiments are explained in detail in the description.

[0017] The valve train according to the invention is configured to carry out the method according to the invention. For this purpose, the valve train comprises a control device in which a computer-readable program algorithm for executing the method and any required characteristic maps are stored.

[0018] The invention is explained below with reference to the accompanying drawings. They show:

[0019] First version:

[0020] Figure 1 shows a sliding cam system of a valve train with an associated actuator and a left and right cam piece on a camshaft, each of which is assigned an actuator arranged in the actuator; Figure 1A shows the sliding cam system of the valve train with its associated actuator with a left actuator and a left cam piece in the first end switching position of the cam piece;

[0021] Figure 1B shows the shifting cam system of the valve train with its associated actuator when switching the left cam piece in an intermediate position between the first and a second end switching position;

[0022] Figure 1C shows the sliding cam system of the valve train with its associated actuator with the left actuator and the left cam piece in the second end switching position of the cam piece;

[0023] Figure 2A shows the sliding cam system of the valve train with its associated actuator with the left actuator and the left cam piece in the second end switching position of the cam piece;

[0024] Figure 2B shows the shifting cam system of the valve train with its associated actuator when switching the left cam piece in an intermediate position between the second and the first end switching position;

[0025] Figure 2C shows the sliding cam system of the valve train with its associated actuator with the left actuator and the left cam piece in the first end switching position of the cam piece;

[0026] Second version:

[0027] Figure 3A shows a sliding cam system of the valve train with its associated actuator with a left actuator and a left cam piece in the first end switching position of the cam piece;

[0028] Figure 3B shows the shifting cam system of the valve train with its associated actuator when switching the left cam piece in an intermediate position between the first and a second end switching position; Figure 3C shows the shifting cam system of the valve train with its associated actuator with the left actuator and the left cam piece in the second end switching position of the cam piece;

[0029] Figure 4A shows the sliding cam system of the valve train with its associated actuator with the left actuator and the left cam piece in the second end switching position of the cam piece;

[0030] Figure 4B shows the shifting cam system of the valve train with its associated actuator when switching the left cam piece in an intermediate position between the second and the first end switching position;

[0031] Figure 4C shows the sliding cam system of the valve train with its associated actuator with the left actuator and the left cam piece in the first end switching position of the cam piece;

[0032] Third variant:

[0033] Figure 5A shows a sliding cam system of the valve train with its associated actuator with a left actuator and a left cam piece in the first end switching position of the cam piece;

[0034] Figure 5B shows the shifting cam system of the valve train with its associated actuator when switching the left cam piece in an intermediate position between the first and a second end switching position;

[0035] Figure 5C shows the sliding cam system of the valve train with its associated actuator with the left actuator and the left cam piece in the second end switching position of the cam piece;

[0036] Figure 6A shows the shifting cam system of the valve train with its associated actuator with the left actuator and the left cam piece in the second end switching position of the cam piece; Figure 6B shows the shifting cam system of the valve train with its associated actuator when switching the left cam piece in an intermediate position between the second and the first end switching position;

[0037] Figure 6C shows the sliding cam system of the valve train with its associated actuator with the left actuator and the left cam piece in the first end switching position of the cam piece;

[0038] Fourth variant:

[0039] Figure 7A shows a sliding cam system of the valve train with its associated actuator with a left actuator and a left cam piece in the first end switching position of the cam piece;

[0040] Figure 7B shows the shifting cam system of the valve train with its associated actuator when switching the left cam piece in an intermediate position between the first and a second end switching position;

[0041] Figure 7C shows the sliding cam system of the valve train with its associated actuator with the left actuator and the left cam piece in the second end switching position of the cam piece;

[0042] Figure 8A shows the sliding cam system of the valve train with its associated actuator with the left actuator and the left cam piece in the second end switching position of the cam piece;

[0043] Figure 8B shows the shifting cam system of the valve train with its associated actuator when switching the left cam piece in an intermediate position between the second and the first end switching position;

[0044] Figure 8C shows the sliding cam system of the valve train with its associated actuator with the left actuator and the left cam piece in the first end switching position of the cam piece; Fifth embodiment:

[0045] Figure 9A shows a sliding cam system of the valve train with its associated actuator with a left actuator and a left cam piece in the first end switching position of the cam piece;

[0046] Figure 9B shows the shifting cam system of the valve train with its associated actuator when switching the left cam piece in an intermediate position between the first and a second end switching position;

[0047] Figure 9C shows the sliding cam system of the valve train with its associated actuator with the left actuator and the left cam piece in the second end switching position of the cam piece;

[0048] Figure 10A shows the sliding cam system of the valve train with its associated actuator with the left actuator and the left cam piece in the second end switching position of the cam piece;

[0049] Figure 10B shows the shifting cam system of the valve train with its associated actuator when switching the left cam piece in an intermediate position between the second and the first end switching position;

[0050] Figure 10C shows the sliding cam system of the valve train with its associated actuator with the left actuator and the left cam piece in the first end switching position of the cam piece;

[0051] Sixth variant:

[0052] Figure 11 A shows a sliding cam system of the valve train with its associated actuator with a left actuator and a left cam piece in the first end switching position of the cam piece;

[0053] Figure 11 B shows the sliding cam system of the valve train with its associated actuator when switching the left cam piece in an intermediate position between the first and a second end switching position; Figure 11 C shows the sliding cam system of the valve train with its associated actuator with the left actuator and the left cam piece in the second end switching position of the cam piece;

[0054] Figure 12A shows the sliding cam system of the valve train with its associated actuator with the left actuator and the left cam piece in the second end switching position of the cam piece;

[0055] Figure 12B shows the shifting cam system of the valve train with its associated actuator when switching the left cam piece in an intermediate position between the second and the first end switching position;

[0056] Figure 12C shows the sliding cam system of the valve train with its associated actuator with the left actuator and the left cam piece in the first end switching position of the cam piece.

[0057] Figure 1 first illustrates some essential structural and functional features of the invention for the multi-stage shifting cam system of a valve train. Multi-stage means that multiple switching positions are possible. Furthermore, multiple cam contours are possible per valve. According to the method and the shifting cam system according to the invention, a two-stage shifting cam system is involved with respect to a first limit switching position E1 and a second limit switching position E2 of the respective cam piece 20L, 20R, as explained below.

[0058] The shifting cam system comprises an actuator 10 having two actuators 1L, 1R, each of which interconnects a first cam piece 20L and a second cam piece 20R. The shifting of a cam piece always occurs via only one of the two actuators.

[0059] The XS shift gate XS has two shift grooves XN, SN of different depths in a single gate or in a single groove of a cam piece 20L, 20R. These shift grooves intersect for space reasons and are therefore arranged at different radial heights in some areas relative to their common center axis M of the camshaft. The different radial heights correspond to the respective depths of the shift grooves XN, SN. The XS shift gate XS is defined with regard to the shift groove depths such that the two shift grooves XN, SN have the same groove depth, at least in some areas, in their respective engagement and disengagement areas.Where the switching grooves XN, SN enter and exit, or the respective actuator 1 L, 1 R engages and disengages, the radial heights of the switching grooves XN, SN are thus the same in some areas relative to the common center axis M of the camshaft.

[0060] The engagement and disengagement areas of each shift groove XN, SN are formed as a transition area in which the respective groove bases of the shift grooves XN, SN run parallel, so that the engagement area of ​​one shift groove XN, SN transitions seamlessly into the disengagement area of ​​the other shift groove XN, SN, wherein the maximum radial height of the shift grooves XN, SN is present in the transition area relative to the common center axis M of the camshaft. In other words, the respective groove depth of the respective groove base is the smallest compared to the groove edges forming the grooves.

[0061] Starting from the transition area in which the switching grooves XN, SN have the same radial amount from the camshaft, the distance of a groove base of one switching groove SN to the camshaft axis decreases further than the distance of a groove base of the other switching groove XN as the respective engagement area progresses, which is also referred to as engagement ramps. This means that the radial distance of the groove base of the switching groove SN becomes smaller as it progresses than the radial distance of the groove base of the switching groove XN, or in other words, the groove depth of the switching groove SN becomes greater than the groove depth of the other switching groove XN as the respective engagement area progresses.

[0062] As a result, the distance of the switching groove SN in the area between the engagement area (engagement ramp) and the disengagement area (disengagement ramp) between the groove base and the camshaft axis is smaller than in the switching groove XN, which is why the switching groove SN is referred to as a deep or deeper switching groove.

[0063] In the area between the entry and exit ramps lies the so-called crossing area, in which the shift groove XN is interrupted and cut by the continuous shift groove SN.

[0064] The crossing area results from the spiral course of the switching grooves XN and SN in the axial direction with respect to the center axis M of the camshaft, which is best seen in Figures 1B to 12B for the left and right cam pieces 20L, 20R, respectively. The spiral course can be compared to the thread of a screw, with one of the switching grooves being designed as a right-hand thread and the other switching groove as a left-hand thread, which is why the intersection of the grooves XN, SN in their course in the crossing area between the engagement area (engagement ramp) and the disengagement area (disengagement ramp) is inevitable.

[0065] The XS link XS is therefore characterized by the fact that outside the transition area it has a deep or deeper groove SN and a less deep groove XN, preferably a groove XN half as deep, which intersects with the S groove.

[0066] The first groove XN, the so-called X-switching groove, is designed as a less deep groove within the gate XS compared to the second groove SN and, as shown in the figures, ensures that the cam piece 20L is displaced to the left.

[0067] The second groove SN, the so-called (deeper) S-switching groove, ensures that the cam piece 20R is displaced to the right, as shown in the figures.

[0068] When the actuator 10 is energized, the respective actuator 1L, 1R moves from its initial position up to the material-side limit by the respective switching groove XN, SN.

[0069] When the current is no longer supplied, the respective actuator 1 L, 1 R remains extended by mechanisms in the actuator 10.

[0070] The actuator 10 has a coil unit 11 L, 11 R for displacing the actuators 1 L, 1 R in the radial direction, while the actuators 1 L, 1 R can be displaced together with their associated permanent magnets.

[0071] The actuators 1L, 1R and a permanent magnet assigned to each actuator 1L, 1R form for each actuator 1L, 1R a movable assembly relative to the coil unit 11L, 11R, a so-called armature assembly.

[0072] The respective coil unit 11 L, 11 R acts on the respective armature assembly. When the coil unit 11 L, 11 R is energized, the actuators 1 L, 1 R, i.e. the pins, are forced from their initial position towards the switching gate XS, as explained in more detail below. The coil units 11 L, 11 R are each electrically connected to a power source via a switching element. If the coil unit is energized, the

[0073] Coil unit 11 L, 11R a magnetic field which urges the permanent magnet of the respective armature assembly in the direction of the switching gate XS, for example until the actuator 1L, 1R touches the switching grooves XN, SN of the XS switching gate XS, i.e. comes into contact on the material side.

[0074] Each of the shift grooves XN, SN has the disengagement ramp, which can displace or force the actuators 1L, 1R out of the shift grooves XN, SN again after the shifting into the shift grooves XN, SN.

[0075] In the off-tracking area assigned to the off-tracking ramp, a distance of a base of the switching grooves XN, SN to the rotation axis becomes continuously larger or an amount of a possible actuating stroke of the actuators 1 L, 1R in the switching grooves XN, SN from the starting position becomes smaller, as will become clear.

[0076] The disengagement ramps are designed in such a way that the actuators 1L, 1R are mechanically completely removed from the switching grooves XN, SN after the cam piece 20L, 20R has been moved, i.e. they are pushed back into their starting position.

[0077] In this case, the actuators 1L, 1R belonging to the respective armature assembly are mechanically pushed back in the direction of the coil unit 11L, 11R until the respective permanent magnet generates an attractive force to the coil unit 11L, 11R, whereby the attractive force of the permanent magnet moves the armature assembly further until it makes contact with the coil unit 11L, 11R, whereby the coil unit 11L, 11R is no longer energized.

[0078] Accordingly, the magnetic force of the permanent magnet(s) causes the actuators 1 L, 1 R to be held in the deployed position, i.e. not engaging in the switching grooves XN, SN, i.e. in their initial position, until the coil unit 11 L, 11 R is energized again by means of the switching element.

[0079] As the actuators 1L, 1R are forced out of the switching grooves XN, SN, a voltage is induced in the coil unit 7, which is detected in an engine control unit and used as an electrical return signal SRÜCK, as will be explained below. The induced voltage is thus converted into the electrical return signal S in the engine control unit. RÜC k is generated, which is used in the process according to the invention.

[0080] In this case, a differential voltage between the induced voltage and the vehicle electrical system voltage will exceed a certain threshold level over a certain period of time. Only when this occurs is the respective return signal SRÜCK generated. The return signal SRÜCK indicates the successful disengagement of the actuator(s) 1L, 1R from the switching grooves XN, SN using the respective disengagement ramp.

[0081] Furthermore, during the active energization of the respective coil unit 11 L, 11 R, a control signal SAnst can be generated, which is also used in certain embodiments for the method according to the invention, as will also be explained below.

[0082] Due to the rotation of the cam pieces 20L, 20R and the spiral course of the switching grooves XN, SN within the XS link XS designed as a groove, the cam pieces 20L, 20R are moved to the left or right by means of the actuators 1L, 1R as shown in the figures.

[0083] At the end of the switching (to the left or right), i.e. the complete displacement, the respective actuator 1 L, 1 R is mechanically pushed back towards its starting position by the disengagement ramp (pushing back the respective actuator 1 L, 1 R), whereby the attraction force of the permanent magnet, the armature assembly, as explained above, ensures that the respective actuator 1 L, 1 R continues to move until it touches the de-energized coil unit 11 L, 11 R.

[0084] When the respective actuator 1L, 1R is retracted, a voltage is induced in the respective coil unit 11L, 11R of the actuator 10. The detected voltage can be used to generate the return signal SRÜCK, which is detected by the engine control unit. This, in combination with other detected parameters explained below, results in a detection logic, with the return signal SRÜCK serving to determine whether the respective actuator 1L, 1R has been retracted, as will be explained in more detail below.

[0085] The return signal SRÜCK indicates whether the respective actuator 1L, 1R has been pushed back. The respective return signal SRÜCK does not detect whether the respective actuator 1L, 1R was previously located in the higher X-groove XN or the lower S-groove SN. In other words, the engine control unit cannot determine the position of the respective actuator 1L, 1R with respect to its assignment to the switching grooves XN, SN based on the return signal SRÜCK alone.

[0086] According to the invention, this assignment is ensured by Hall sensors 12L, 12R. Depending on the design variant, a Hall sensor 12L, 12R is assigned to each of the actuators 1L, 1R, or only one Hall sensor 12M is assigned to the actuators 1L, 1R. The Hall sensors 12L, 12R; 12M are arranged in the actuator 10 according to the design variants, which are explained in detail below.

[0087] By evaluating the Hall sensor(s) 12M; 12L, 12R, it can be determined how far the respective actuator 1L, 1R was extended from its initial position.

[0088] Each actuator 1L, 1R of an actuator 10 is thus equipped with at least one Hall sensor 12M or 12L, 12R, depending on the design variant.

[0089] Each Hall sensor 12L, 12R; 12M can calculate different voltage levels as a duty cycle (the number can be specified) depending on the measured field strength and output them as a PWM voltage signal to the engine control unit.

[0090] One and the same actuator 1L, 1R controls both switching grooves XN, SN, which are also referred to as switching grooves, at different times and can thus switch each of the cam pieces 20L, 20R back and forth between the first end switching position 1 and the second end switching position 2 (two-stage), i.e. switch.

[0091] The respective actuator 1L, 1R can, as explained below, be retracted, extended and, for example, only half extended.

[0092] These three states are provided, according to the invention, with a duty cycle between 0% and 100% as a 5 V PWM signal by the Hall sensor(s) 12M; 12L, 12R. The engine control unit can detect these PWM signal value ranges. These states are assigned to stroke positions of the respective actuator 1L, 1R, which will be discussed in more detail below.

[0093] In other words, a predeterminable number of two or three stroke positions is preferably formed for each actuator 1L, 1R, as will be explained below. Preferably, in the embodiments explained below, the stroke position "E = retracted" and the stroke position "EA = half extended" and the stroke position "A = extended" are formed for each actuator 1L, 1R by means of the Hall sensors 12L, 12R, which are detected by means of the 5 V PWM signal, wherein a PWM signal range between 0 - 33% is assigned the stroke position E "retracted", a PWM signal range 34 - 66% is assigned the stroke position EA "half extended" and a PWM signal range 67 - 100% is assigned the stroke position A "fully extended".

[0094] As will be explained later using design variants, it is also possible to record only two stroke positions.

[0095] Using the electrical PWM signal or the determined PWM signal ranges of the respective Hall sensors 12M; 12L, 12R, it is thus possible to evaluate in the engine control unit, in which stroke positions assigned to the PWM signal ranges the respective actuator 1L, 1R has been moved into the switching grooves XN, SN, as will be clarified in the exemplary embodiments.

[0096] In combination with the return signal SRÜCK of the respective actuator 1L, 1R, the engine control unit can also advantageously evaluate that the switching of the respective cam piece 20L, 20R was successfully carried out, as becomes clear from the explanation of the design variants.

[0097] As a result, it is advantageously possible to clearly determine the position of the cam pieces 20L, 20R by combining the detected PWM signal ranges, i.e. the respective stroke positions and the respective return signal SRÜCK of the respective actuator 1L, 1R.

[0098] This means that each cam piece 20L, 20R can advantageously always be clearly assigned its two axial end switching positions E1, E2 located along the center axis M of the camshaft, whereby the engine control unit can specifically initiate the next switching process if necessary, knowing the respective end switching position E1, E2.

[0099] With the help of this structural and functional design, it is possible in various

[0100] In some embodiments, it is advantageously possible to clearly detect the position of the cam pieces 20L, 20R, as will be explained in detail below using exemplary embodiments.

[0101] First version:

[0102] Each actuator 1L, 1R of the actuator 10 is equipped with a Hall sensor 12L, 12R. The Hall sensors 12L, 12R according to the first embodiment are configured to output the stroke position of the respective actuator 1L, 1R in three PWM signal ranges, depending on the displacement travel.

[0103] As explained, the PWM signal ranges allow the engine control unit to distinguish between three different stroke positions with respect to the respective actuator 1L, 1R.

[0104] This means that the engine control unit can use the PWM signal to distinguish whether the respective actuator 1L, 1R is “retracted” in stroke position E, “only half extended” in stroke position EA, or “fully extended” in stroke position A.

[0105] According to the first embodiment, each actuator 1L, 1R of an actuator 10 is additionally assigned a two-stage return signal SRÜCK = 0 or = 1. The return signal SRÜCK can be used to detect the retraction process of the respective actuator 1L, 1R, whereby the resulting procedure for detecting the position of the cam pieces 20L, 20R is explained below. The return signal SRÜCK = 1 describes that a return signal SRÜCK has been detected by the engine control unit, thus completing the switching process. The return signal SRÜCK = 1 is only present for a short time and, depending on the application, can be used to set a flag in the application program of the engine control unit, which is reset, for example, as soon as the position detection of the cam pieces 20L, 20R is completed.

[0106] In detail: If the induced voltage in the coil unit 11 L, 11 R is below a voltage threshold at a certain point in time, the return signal SRÜCK = 0 is set. This means that the mechanically induced insertion of the actuator 1 L, 1 R has not (yet) occurred.

[0107] If the induced voltage in the coil unit 11 L, 11 R is above a voltage threshold value at a specific time for a specific predefined period of time, the return signal SRÜCK = 1 is set. This means that the mechanically induced insertion of the actuator 1 L, 1 R has taken place.

[0108] The specific time depends on the motor speed and the XS groove geometry. The time is time-delayed and occurs after the time of actuation of actuator 1L, 1R. The voltage signal is expected to be above the voltage threshold and is detected when the respective actuator 1L, 1R returns to its retracted stroke position E.

[0109] Explanation of the position detection according to the first design variant using the deeper switching groove SN of the left cam piece 20L:

[0110] Figures 1A to 1C are assigned to Tables 1A to 1C, i.e. Table 1A belongs to Figure 1A, Table 1B to Figure 1B and Table 1C to Figure 1C.

[0111] Table 1A and Figure 1A show an initial position of the actuators 1L, 1R. The cam pieces 20L, 20R are in their first end switching position E1.

[0112] The switching of the lower switching groove SN is performed starting from a switching position of the lower switching groove SN according to the last memory state or an initialization circuit. In addition, all markers for the Hall sensors 12L, 12R and the return signal SRÜCK for the left actuator 1L in the engine control unit are first reset, because the lower switching groove SN of the left cam piece 20L is to be switched.

[0113] In the initial position according to Figure 1A and Table 1A, the Hall sensors 12L, 12R each register a Hall sensor signal in the PWM signal range E = 0 - 33%, which means that the actuators 1L, 1R are in the "retracted" stroke position. The detected return signals SRÜCK = 0, which means that the engine control unit is not detecting a return signal SRÜCK at the current time. According to Figure 1B and Table 1B, the Hall sensor signal changes to the PWM signal range A = 67 - 100%, which means that the actuator 1L is in the "fully extended" stroke position, i.e., the left cam piece 1L has been switched to the right from the end switching position E1 to the end switching position E2. The Hall sensor signal in the PWM signal range A = 67 - 100% means that it has been detected and thus ensured that the left actuator 1 L has engaged in the deeper switching groove SN.

[0114] According to Figure 1C and Table 1C, the Hall sensor signal changes into the PWM signal range E = 0 - 33%, which means that the actuator 1L is retracted into the stroke position again, with a detected return signal SRÜCK = 1, whereby the process of resetting the left actuator 1L from the deeper switching groove SN is checked, i.e. confirmed by the return signal SRÜCK = 1.

[0115] Explanation of the position detection of the first design variant based on the higher switching groove XN of the left cam piece 20L:

[0116] Figures 2A to 2C are assigned to Tables 2A to 2C, i.e. Table 2A belongs to Figure 2A and Table 2B to Figure 2B, and Table 2C to Figure 2C.

[0117] Table 2A and Figure 2A show an initial position of the actuators 1L, 1R. The cam piece 20L is in its second end switching position E2 according to Figure 1C.

[0118] The switching of the higher switching groove XN is carried out starting from a switching position of the higher switching groove XN according to the last memory state or an initialization circuit. In addition, all markers for the Hall sensors 12L, 12R and the return signal SRÜCK for the left actuator 1L in the engine control unit are reset first, because the higher switching groove XN of the left cam piece 20L is to be switched. In the initial position according to Figure 2A and Table 2A, the Hall sensors 12L, 12R each register a Hall sensor signal in the PWM signal range E = 0 - 33%, i.e., the actuators 1L, 1R are "retracted." At this point in time, the recorded return signals SRÜCK = 0.

[0119] According to Figure 2B and Table 2B, the Hall sensor signal changes to the PWM signal range EA = 34 - 66%, meaning that the actuator 1L is in the stroke position "extended halfway," meaning that the left cam piece 1L has been switched back to the left from the end switching position E2 to the end switching position E1. The Hall sensor signal in the PWM signal range EA = 34 - 66% advantageously means that it has been detected and thus ensured that the left actuator 1L has engaged the higher switching groove XN and not the lower switching groove SN.

[0120] According to Figure 20 and Table 20, the Hall sensor signal changes into the PWM signal range E = 0 - 33%, which means that the actuator 1L is again in the stroke position "retracted", with a detected return signal SRÜCK = 1, whereby the process of resetting the left actuator 1L from the higher switching groove XN is checked, i.e. confirmed by the return signal SRÜCK = 1.

[0121] Second version:

[0122] Each actuator 1L, 1R of an actuator 10 is also equipped with a Hall sensor 12L, 12R. According to the second embodiment, in contrast to the first embodiment, the signals from the Hall sensors 12L, 12R are processed in the engine control unit in such a way that only two PWM signal ranges are distinguished.

[0123] According to the two PWM signal ranges, only two stroke positions of the respective actuator 1L, 1R are provided. Because the engine control unit distinguishes between only two different stroke positions, lower resolution requirements for the Hall sensors are advantageously achieved. In other words, less expensive Hall sensors can be used if necessary.

[0124] Unlike the previous embodiment, the respective Hall sensor 12L, 12R of the actuator 1L, 1R according to the second embodiment cannot distinguish between the PWM signal range E "retracted" and the PWM signal range EA "halfway extended." The PWM signal range that differs from the PWM signal range A "extended" is referred to in this embodiment as the PWM signal range E' "not fully extended."

[0125] E' illustrates a stroke position of the respective actuator 1L, 1R, which differs from the stroke position A “fully extended”.

[0126] Depending on how the PWM signal ranges are divided (for example 70% / 30% or 50% / 50%), the engine control unit can only distinguish between two stroke positions, whether the respective actuator 1L, 1R is in stroke position A “fully extended” or in stroke position E' “not fully extended”.

[0127] Each actuator 1L, 1R of an actuator 10 is additionally assigned the respective two-stage return signal SRÜCK = 0 or = 1. The return signal SRÜCK can be used to detect whether a retraction process of the respective actuator 1L, 1R has taken place, whereby the resulting procedure for detecting the position of the cam pieces 20L, 20R is explained below.

[0128] Explanation of the position detection according to the second design variant using the deeper switching groove SN of the left cam piece 20L:

[0129] Figures 3A to 3C are assigned to Tables 3A to 3C, i.e. Table 3A belongs to Figure 3A and Table 3B to Figure 3B, and Table 3C to Figure 3C.

[0130] Table 3A and Figure 3A show an initial position of the actuators 1L, 1R. The cam pieces 20L, 20R are in their first end switching position E1.

[0131] The switching of the lower switching groove SN is initiated based on a switching position of the lower switching groove SN according to the last memory state or an initialization circuit. In addition, all markers for the Hall sensors 12L, 12R and the return signal SRÜCK for the left actuator 1L in the engine control unit are first reset.

[0132] In the initial position shown in Figure 3A and Table 3A, the Hall sensors 12L, 12R each register a Hall sensor signal in the PWM signal range E' < 70%, meaning the actuators 1L, 1R are "not fully extended." The detected return signals SRÜCK are 0 at this time.

[0133] According to Figure 3B and Table 3B, the Hall sensor signal changes into the PWM signal range A > 70%, which means that the actuator 1L is in the stroke position “fully extended”, which means that the left cam piece 1L has been switched to the right from the end switching position E1 to the end switching position E2.

[0134] The Hall sensor signal in the PWM signal range A > 70% means that the change of the PWM signal ranges E' to A has been detected and thus it is ensured that the left actuator 1 L has engaged in the deeper switching groove SN.

[0135] According to Figure 3C and Table 3C, the Hall sensor signal changes back to the PWM signal range E' < 70%, i.e., the actuator 1L is again in the stroke position "not extended", with a detected return signal SRÜCK = 1, whereby the process of resetting the left actuator 1L from the lower switching groove SN in the end switching position E2 of the cam piece 1L is checked, i.e., confirmed by the return signal SRÜCK = 1.

[0136] Explanation of the position detection of the second design variant using the right higher switching groove XN of the left cam piece 20L:

[0137] Figures 4A to 4C are assigned to Tables 4A to 4C, i.e. Table 4A belongs to Figure 4A and Table 4B to Figure 4B, and Table 4C to Figure 4C. Table 4A and Figure 4A show an initial position of the actuators 1L, 1R. The cam piece 20L is in its second end switching position E2 according to Figure 3C.

[0138] The switching of the higher switching groove XN is performed starting from a switching position of the higher switching groove XN according to the last memory state or an initialization circuit. In addition, all markers for the Hall sensors 12L, 12R and the return signal SRÜCK for the left actuator 1L in the engine control unit are first reset, because the higher switching groove XN of the left cam piece 20L is to be switched.

[0139] In the initial position according to Figure 4A and Table 4A, the Hall sensors 12L, 12R each register a Hall sensor signal in the PWM signal range E' < 70%, meaning that the actuators 1L, 1R are "not fully extended." The detected return signals SRÜCK are 0 at this time.

[0140] According to Figure 4B and Table 4B, the Hall sensor signal of the left actuator 1L does not change within the PWM signal range A > 70%. It remains unchanged within the PWM signal range E' < 70%. This means that the actuator 1L was extended within the PWM signal range but "not fully extended" within the PWM signal range E', and the left cam piece 1L was switched back to the left from the end switching position E2 to the end switching position E1.

[0141] The unchanged Hall sensor signal in the PWM signal range E' < 70% means that despite the initiation of a switching operation, no change in the PWM signal ranges was detected and thus it is ensured that the left actuator 1L has engaged in the higher switching groove XN.

[0142] According to Figure 4G and Table 4C, the Hall sensor signal does not change, i.e., the actuator 1 L has been retracted, since a detected return signal SRÜCK ZU is = 1 at this time, whereby the process of resetting the left actuator 1 L from the higher switching groove XN is checked, i.e., confirmed by the return signal SRÜCK = 1.

[0143] Third variant:

[0144] In contrast to the previous examples, both actuators 1 L, 1 R of an actuator 10 are

[0145] In some versions, only one Hall sensor 12M is assigned. The Hall sensor is located centrally in the actuator 10 (relative to the vertical longitudinal extension of the actuator 10 in the figures) and senses both actuators 11L, 11R.

[0146] In contrast to the first embodiment, the Hall sensor 12M according to the third embodiment is equipped in such a way that (analogous to the second embodiment) it outputs (only) two different PWM signal ranges, which correspond to two stroke positions of the actuator 1L.

[0147] As in the previous design variant, the Hall sensor 12M of the actuators 1 L, 1 R cannot distinguish between the stroke position E “retracted” and the stroke position EA “only half extended”.

[0148] The PWM signal range that differs from the "extended" PWM signal range A is referred to as the "not fully extended" PWM signal range E' in this design variant. E' represents a PWM signal range that differs from the "fully extended" PWM signal range A.

[0149] Depending on how the PWM signal ranges are divided (for example 70% / 30% or 50% / 50%), the engine control unit can only distinguish between two stroke positions, whether the respective actuator 1L, 1R is in stroke position A “fully extended” or in stroke position E' “not fully extended”.

[0150] Each actuator 1L, 1R of an actuator 10 is additionally assigned the respective two-stage return signal SRÜCK = 0 or = 1. The return signal SRÜCK can be used to detect whether a retraction process of the respective actuator 1L, 1R has taken place, whereby the resulting procedure for detecting the position of the cam pieces 20L, 20R is explained below.

[0151] Explanation of the position detection according to the third embodiment variant using the deeper switching groove SN of the left cam piece 20L: Figures 5A to 5C are assigned to Tables 5A to 5C, i.e. Table 5A belongs to Figure 5A and Table 5B to Figure 5B and Table 5C to Figure 5C.

[0152] Table 5A and Figure 5A show an initial position of the actuators 1L, 1R. The cam pieces 20L, 20R are in their first end switching position E1.

[0153] The switching of the lower switching groove SN is performed starting from a switching position of the lower switching groove SN according to the last memory state or an initialization circuit. In addition, all flags of the Hall sensor 12M and the return signal SRÜCK for the left actuator 1L in the engine control unit are reset first.

[0154] In the initial position according to Figure 5A and Table 5A, the Hall sensor 12M registers a Hall sensor signal in the PWM signal range E' < 70%, meaning that the actuators 1L, 1R are "not fully extended." The detected return signals SRÜCK are 0 at this time.

[0155] According to Figure 5B and Table 5B, the Hall sensor signal changes into the PWM signal range A > 70%, which means that the actuator 1L has been “fully extended”, which means that the left cam piece 1L has been switched to the right from the end switching position E1 to the end switching position E2.

[0156] The Hall sensor signal in the PWM signal range A > 70% means that the change in the PWM signal ranges has been detected and thus it is ensured that the left actuator 1 L has engaged in the deeper switching groove SN.

[0157] According to Figure 50 and Table 5C, the Hall sensor signal changes back in the PWM signal range E' < 70%, i.e. the actuator 1L has been retracted or is "not fully extended", with a detected return signal SRÜCK = 1, whereby the return of the left actuator 1L from the deeper switching groove SN in the end switching position E2 of the cam piece 1L is checked, i.e. confirmed by the return signal SRÜCK = 1.

[0158] Explanation of the position detection of the third design variant using the right higher switching groove XN of the left cam piece 20L:

[0159] Figures 6A to 6C are assigned to Tables 6A to 6C, i.e. Table 6A belongs to Figure 6A and Table 6B to Figure 6B, and Table 6C to Figure 6C.

[0160] Table 6A and Figure 6A show an initial position of the actuators 1L, 1R. The cam piece 20L is in its second end switching position E2 according to Figure 5C.

[0161] The switching of the higher switching groove XN is performed starting from a switching position of the higher switching groove XN according to the last memory state or an initialization circuit. In addition, all markers for the Hall sensor 12M and the return signal SRück for the left actuator 1L in the engine control unit are reset first, because the higher switching groove XN of the left cam piece 20L is to be switched.

[0162] In the initial position according to Figure 6A and Table 6A, the Hall sensor 12M registers a Hall sensor signal in the PWM signal range E' < 70%, meaning that the actuators 1L, 1R are "not fully extended." The detected return signals at this time are 0.

[0163] According to Figure 6B and Table 6B, the Hall sensor signal of the left actuator 1L does not change in the PWM signal range A > 70%. It remains unchanged according to the PWM signal range E' < 70%. This means that the actuator 1L was "not fully extended" and the left cam piece 1L was switched back to the left from the end switching position E2 to the end switching position E1. The unchanged Hall sensor signal in the PWM signal range E' < 70% means that, despite the initiation of a switching operation, no change in the PWM signal ranges was detected, thus ensuring that the left actuator 1L has engaged the higher switching groove XN.

[0164] According to Figure 60 and Table 60, the Hall sensor signal does not change, which means that the actuator 1L has been retracted again, since a detected return signal SRÜCK = 1, whereby the return of the left actuator 1L from the higher switching groove XN is checked, which means that it is confirmed by the return signal SRÜCK = 1.

[0165] Fourth variant:

[0166] In contrast to the previous embodiments, only one Hall sensor 12M is assigned to both actuators 1L, 1R of an actuator 10. The Hall sensor 12M is arranged centrally in the actuator 10 (relative to the vertical longitudinal extension of the actuator 10 in the figures) and senses both actuators 11L, 11R.

[0167] In contrast to the first embodiment, the Hall sensor 12M according to the fourth embodiment is equipped in such a way that (analogous to the second embodiment) it outputs (only) two different PWM signal ranges, which correspond to two stroke positions of the actuator 1L.

[0168] As in the previous design variant, the Hall sensor 12M of the actuators 1 L, 1 R cannot distinguish between the stroke position E “retracted” and the stroke position EA “only half extended”.

[0169] The PWM signal range that differs from the "extended" PWM signal range A is referred to in this design variant as the "not fully extended" PWM signal range E'. E' represents a PWM signal range that differs from the "fully extended" PWM signal range of stroke position A.

[0170] Depending on how the PWM signal ranges are divided (for example 70% / 30% or 50% / 50%), the engine control unit can only distinguish between two stroke positions, whether the respective actuator 1L, 1R is in stroke position A “fully extended” or in stroke position E' “not fully extended”.

[0171] In contrast to the third embodiment, a return signal SRÜCK can no longer be detected separately for each actuator 1L, 1R of an actuator 10. In this fourth embodiment, the return signal SRÜCK can be used to detect the retraction process of the respective actuator 1L, 1R "only without direct assignment" to the actuators 1L, 1R.

[0172] The engine control unit can no longer distinguish based on the return signal SRÜCK whether the left or right actuator 1 L, 1 R has been reset.

[0173] As already explained in the introduction, when the actuator 10 is energized, the respective actuator 1 L, 1 R extends to the maximum material limit defined by the respective switching groove XN, SN. When the energization of the respective actuator 1 L, 1 R ceases, the respective actuator 1 L, 1 R remains extended in the actuator 10 due to mechanical mechanisms, in particular the armature assembly belonging to the respective actuator.

[0174] In other words, it is possible to generate a control signal SAnst = 0 (not energized) and = 1 (energized) from the energization signal generated by the engine control unit, which, as a control signal SAnst, signals that the left actuator 1 L or the right actuator 1 R is energized and has therefore probably been switched and extended.

[0175] The position detection according to the fourth embodiment variant, whether the left actuator 1 L or the right actuator 1 R is energized, uses this possibility, whereby the resulting procedure for the position detection of the cam pieces 20L, 20R is explained below.

[0176] Explanation of the position detection according to the fourth design variant using the deeper switching groove SN of the left cam piece 20L:

[0177] Figures 7A to 7C are assigned to Tables 7A to 7C, i.e. Table 7A belongs to Figure 7A and Table 7B to Figure 7B, and Table 7C to Figure 7C. Table 7A and Figure 7A show an initial position of the actuators 1 L, 1 R. The cam pieces 20L, 20R are in their first end switching position E1 .

[0178] The switching of the lower switching groove SN is performed starting from a switching position of the lower switching groove SN according to the last memory state or an initialization circuit. In addition, all markers for the Hall sensor 12M and the return signal SRÜCK for the left actuator 1L in the engine control unit are reset first.

[0179] In the initial position according to Figure 7A and Table 7A, the Hall sensor 12M registers a Hall sensor signal in the PWM signal range E < 70%, meaning that the actuators 1L, 1R are "not fully extended." The detected return signal SRÜCK is 0 at this time.

[0180] According to Figure 7B and Table 7B, the Hall sensor signal changes to the PWM signal range A > 70% and is registered as the control signal SAnst = 1. This means that the left actuator 1L has been energized. This also means that the left actuator 1L has been "fully extended." The left cam piece 1L is switched to the right from the end switching position E1 to the end switching position E2.

[0181] The Hall sensor signal in the PWM signal range A > 70% in combination with the control signal SAnst = 1 means that the change in the PWM signal ranges and the control signal SAnst = 1 has been detected and thus ensures that the left actuator 1 L has engaged in the deeper switching groove SN.

[0182] According to Figure 7C and Table 7C, the Hall sensor signal changes back to the PWM signal range E' < 70%, which means that the actuator 1 L is again in the stroke position "not fully extended", whereby the detected return signal SRÜCK = 1 is now checked, whereby the return of the left actuator 1 L from the deeper switching groove SN in the end switching position E2 of the cam piece 1 L is checked, which means that it is not directly but indirectly confirmed by the return signal SRÜCK = 1, since the left actuator 1 L has been energized according to the detected control signal SAnst = 1.

[0183] Explanation of the position detection of the fourth embodiment variant based on the right higher switching groove XN of the left cam piece 20L: Figures 8A to 8C are assigned to Tables 8A to 8C, i.e. Table 8A belongs to Figure 8A and Table 8B to Figure 8B as well as Table 8C to Figure 8C.

[0184] Table 8A and Figure 8A show an initial position of the actuators 1 L, 1 R. The

[0185] Cam piece 20L is in its second end switching position E2 according to Figure 7C.

[0186] The switching of the higher switching groove XN is performed starting from a switching position of the higher switching groove XN according to the last memory state or an initialization circuit. In addition, all markers for the Hall sensors 12L, 12R and the return signal SRÜCK for the left actuator 1L in the engine control unit are first reset, because the higher switching groove XN of the left cam piece 20L is to be switched.

[0187] In the initial position according to Figure 8A and Table 8A, the Hall sensor 12M registers a PWM signal in the PWM signal range E' < 70%, meaning that the actuators 1L, 1R are "not fully extended." The detected return signal SRÜCK is 0 at this time.

[0188] According to Figure 8B and Table 8B, the Hall sensor signal of the left actuator 1L does not change in the PWM signal range A > 70%. It remains unchanged in the PWM signal range E' < 70%.

[0189] This means that the actuator 1 L was indeed extended and the left cam piece 1 L was switched back to the left from the end switching position E2 to the end switching position E1. The unchanged Hall sensor signal in the PWM signal range E' < 70% means that despite the initiation of a switching operation, no change in the PWM signal ranges was detected, which ensures that the left actuator 1 L has engaged the higher switching groove XN. A return signal SRÜCK is also not present at this time, i.e., it remains = 0. However, the control signal SAnst = 1 specifies that only actuator 1 L can have been energized.

[0190] According to Figure 80 and Table 80, the PWM signal range of the Hall sensor signal does not change. However, actuator 1L has been "retracted" again without the PWM signal range of Hall sensor 12M changing, since the detected return signal SRÜCK = 1. Although the return signal SRÜCK cannot be clearly assigned to one or the other actuator 1L, 1R, the control signal SAnst = 1 ensures that the return signal SRÜCK = 1 originates only from the actuator that was also energized according to the control signal SAnst = 1, thereby verifying, i.e., confirming, the return of the left actuator 1L from the higher switching groove XN.

[0191] Fifth variant:

[0192] The fifth design variant is again based on the first design variant, but the detection of the return signal SRÜCK is omitted.

[0193] In contrast to the first embodiment, a Hall sensor 12M is used as the Hall sensor 12M arranged centrally in the actuator 10 (relative to the vertical longitudinal extent of the actuator 10 in the figures), which, in contrast to the previous embodiments, is capable of sensing both actuators 11L, 11R with regard to their position in regions, wherein the centrally arranged Hall sensor 12M is designed such that it can clearly assign the detected PWM signal ranges, i.e. the associated stroke positions, to the left or right actuator 1L, 1R with a time delay.

[0194] This means that both actuators 1L, 1R of actuator 10 are detected by the same centrally located Hall sensor 12M. The Hall sensor 12M according to the fifth embodiment is equipped in such a way that it can output three different PWM signal ranges (for both actuators 1L, 1R) in certain areas, corresponding to the stroke position of the actuators 1L, 1R. Such a Hall sensor therefore has higher resolution requirements, since it senses both actuators 1L, 1R of actuator 10 when centrally located.

[0195] This means that the engine control unit can use the PWM signal to distinguish whether the respective actuator 1L, 1R is “retracted” in the PWM signal range E or “only half extended” in the PWM signal range EA or “fully extended” in the PWM signal range A, whereby the resulting procedure for detecting the position of the cam pieces 20L, 20R is explained below.

[0196] Explanation of the position detection according to the fifth design variant using the deeper switching groove SN of the left cam piece 20L:

[0197] Figures 9A to 9C are assigned to Tables 9A to 9C, i.e. Table 9A belongs to Figure 9A and Table 9B to Figure 9B, and Table 9C to Figure 9C.

[0198] Table 9A and Figure 9A show an initial position of the actuators 1L, 1R. The cam pieces 20L, 20R are in their first end switching position E1.

[0199] The switching of the lower switching groove SN is performed starting from a switching position of the lower switching groove SN according to the last memory state or an initialization circuit. In addition, all flags for the Hall sensor 12M for the left actuator 1L in the engine control unit are first reset, because the lower switching groove SN of the left cam piece 20L is to be switched.

[0200] In the initial position according to Figure 9A and Table 9A, the Hall sensor 12M registers a Hall sensor signal in the PWM signal range E = 0 - 33%, i.e. the actuators 1L, 1R are "retracted".

[0201] According to Figure 9B and Table 9B, the Hall sensor signal changes in the PWM signal range A = 67 - 100%, which means that the actuator 1L has been "fully extended," meaning that the left cam piece 1L has been switched to the right from the end switching position E1 to the end switching position E2. The Hall sensor signal in the PWM signal range

[0202] A = 67 - 100 % means that it has been detected and thus ensured that the left actuator 1 L has engaged in the deeper switching groove SN.

[0203] According to Figure 9C and Table 9C, the Hall sensor signal changes back to the PWM signal range E = 0 - 33%, which means that the actuator 1 L has been "retracted" again. Explanation of the position detection of the fifth embodiment based on the higher

[0204] Switching groove XN of the left cam piece 20L:

[0205] Tables 10A to 10C are assigned to Figures 10A to 10C, i.e. Table 10A belongs to Figure 10A and Table 10B to Figure 10B, and Table 10C to Figure 10C.

[0206] Table 1OA and Figure 1OA show an initial position of the actuators 1 L, 1 R. The cam piece 20L is in its second end switching position E2 according to Figure 9C.

[0207] The switching of the higher switching groove XN is performed starting from a switching position of the higher switching groove XN according to the last memory state or an initialization circuit. In addition, all flags for the Hall sensor 12M for the left actuator 1L in the engine control unit are first reset, because the higher switching groove XN of the left cam piece 20L is to be switched.

[0208] In the initial position according to Figure 10A and Table 10A, the Hall sensor 12M registers a Hall sensor signal in the PWM signal range E = 0 - 33%, which means that the actuators 1 L, IR are "retracted".

[0209] According to Figure 10B and Table 10B, the Hall sensor signal changes to the PWM signal range EA = 33 - 66%, meaning that the actuator 1L has been "extended halfway," meaning that the left cam piece 1L has been switched back to the left from the end switching position E2 to the end switching position E1. The Hall sensor signal in the PWM signal range EA = 33% to 66% means that it has been detected and thus ensured that the left actuator 1L has engaged the higher switching groove XN.

[0210] According to Figure 10C and Table 10C, the Hall sensor signal changes back to the PWM signal range E = 0 - 33%, meaning that actuator 1L has been "retracted" again. Sixth design variant:

[0211] The sixth embodiment variant is based on the first embodiment variant, but again the detection of the return signal SRÜCK is omitted.

[0212] Both actuators 1L, 1R of the actuator 10 are equipped with their own Hall sensor 12L, 12R. The Hall sensor 12M according to the sixth embodiment is again equipped such that it can output (for both actuators 11L, 11R) three different PWM signal ranges, which correspond to the stroke position of the actuators 1L, 1R.

[0213] This means that the engine control unit can distinguish based on the PWM signal range whether the respective actuator 1L, 1R is “retracted” in the PWM signal range E or “only half extended” in the PWM signal range EA or “extended” in the PWM signal range A, whereby the resulting procedure for detecting the position of the cam pieces 20L, 20R is explained below.

[0214] Explanation of the position detection according to the sixth design variant using the deeper switching groove SN of the left cam piece 20L:

[0215] Figures 11A to 11C are assigned to Tables 11A to 11C, i.e. Table 11A belongs to Figure 11A and Table 11B to Figure 11B, and Table 11C to Figure 11C.

[0216] Table 11A and Figure 11A show an initial position of the actuators 1L, 1R. The cam pieces 20L, 20R are in their first end switching position E1.

[0217] The switching of the lower switching groove SN is performed starting from a switching position of the lower switching groove SN according to the last memory state or an initialization circuit. In addition, all flags for the Hall sensors 12L, 12R for the left actuator 1L in the engine control unit are first reset, because the lower switching groove SN of the left cam piece 20L is to be switched. In the initial position according to Figure 11A and Table 11A, the Hall sensors 12L, 12R each register a Hall sensor signal in the PWM signal range E = 0 - 33%, i.e., the actuators 1L, 1R are "retracted."

[0218] According to Figure 11B and Table 11B, the Hall sensor signal changes to the PWM signal range A = 67 - 100%, which means that the left actuator 1L has been extended, i.e., the left cam piece 1L has been switched to the right from the end switching position E1 to the end switching position E2. The Hall sensor signal in the PWM signal range

[0219] A = 67 - 100 % means that it has been detected and thus ensured that the left actuator 1 L has engaged in the deeper switching groove SN.

[0220] According to Figure 11C and Table 11C, the Hall sensor signal changes back to the PWM signal range E = 0 - 33%, which means that the actuator 1 L has been "retracted" again.

[0221] Explanation of the position detection of the sixth design variant based on the higher switching groove XN of the left cam piece 20L:

[0222] Figures 12A to 12C are assigned to Tables 12A to 12C, i.e. Table 12A belongs to Figure 12A and Table 12B to Figure 12B, and Table 12C to Figure 12C.

[0223] Table 12A and Figure 12A show an initial position of the actuators 1L, 1R. The cam piece 20L is in its second end switching position E2 according to Figure 11C.

[0224] The switching of the higher switching groove XN is performed starting from a switching position of the higher switching groove XN according to the last memory state or an initialization circuit. In addition, all flags for the Hall sensors 12L, 12R for the left actuator 1L in the engine control unit are first reset, because the higher switching groove XN of the left cam piece 20L is to be switched.

[0225] In the initial position according to Figure 12A and Table 12A, the Hall sensors 12L, 12R each register a Hall sensor signal in the PWM signal range E = 0 - 33%, meaning that the actuators 1L, 1R are "retracted." According to Figure 12B and Table 12B, the Hall sensor signal changes to the PWM signal range EA = 34 - 66%, meaning that the actuator 1L has been "extended halfway," meaning that the left cam piece 1L has been switched back to the left from the end switching position E2 to the end switching position E1. The Hall sensor signal in the PWM signal range EA = 33% - 66% means that it has been detected and thus ensured that the left actuator 1L has engaged in the higher switching groove XN.

[0226] According to Figure 12C and Table 12C, the PWM signal range of the Hall sensor signal changes back to the PWM signal range E = 0 - 33%, which means that the left actuator 1 L is "retracted" again.

[0227] It is additionally important that the position detection of the right cam piece 20R is carried out analogously to the previous description of the left cam piece 20L.

[0228] In the design variants 1, 2, 6, it is possible to move the cam pieces 20L, 20R simultaneously or with a time delay axially on the center axis M of the camshaft relative to the camshaft, because each actuator 1L, 1R is assigned a unique position detection.

[0229] In design variants 3, 4, and 5, it is only possible to move the cam pieces 20L, 20R axially offset relative to the camshaft on the center axis M of the camshaft, since the position detection cannot be clearly assigned to any of the actuators 1L, 1R in the case of simultaneous or temporally overlapping switching operations. In such cases, it is not possible to distinguish whether the left or right actuator 1L, 1R was switched in the case of simultaneous or temporally overlapping switching operations.

[0230] Regardless of the design variant, it is also important that the engine control unit cannot initially distinguish the current position (operating position, end switching position E1 or end switching position E2, or between E1 and E2) of the cam pieces 20L, 20R, 1L, 1R when the engine is started. It is intended that a test switching, i.e., the initialization switching, is performed after a minimum speed is reached.

[0231] One of the design variants therefore always serves to determine the current position of the respective cam piece 20L, 20R when the minimum speed is reached. By test-switching each actuator 1L, 1R (as explained in the design variants), it is possible to determine which groove SN or XN the actuator 1L, 1R is currently engaging at a given time.

[0232] From this, it can be deduced in which position the respective cam piece 20L, 20R is currently located at the end of the test circuit, so that after this initialization, the position of the respective cam piece 20L, 20R is available in the engine control unit as a final memory status.

[0233] During operation (see Figure 1), the cam contours 20L-N and 20L-V of a cam piece 20L or, in the case of the cam piece 20R, the cam contours 20R-N and 20R-V, which are present per valve of a cylinder of an internal combustion engine, are axially displaced.

[0234] The respective cam contour is transmitted to the valve (not shown) via a roller cam follower. The displacement mechanism is activated by the actuator 10 for each cam piece 20L, 20R. The actuator 1L, 1R, in the form of a pin, engages the respective switching groove SN, XN of the cam pieces 20L, 20R.

[0235] The respective cam piece 20L, 20R is moved back and forth between two cam lift contours depending on the engaging cam contours 20L-N, 20L-V of the respective cam piece 20L or, in the case of the cam piece 20R, depending on the cam contours 20R-N, 20R-V.

[0236] The valves and thus the combustion chambers of the cylinders belonging to cam section 20L, 20R remain closed when using cam contour 20R-N, 20L-N. For example, fuel injection in the respective cylinder(s) is simultaneously shut off, and they continue to run without firing.

[0237] The end switching positions E1 and E2 explained in the embodiments are assigned to the full stroke or the zero stroke.

[0238] Position detection and the structural and functional approaches described above can thus be used advantageously for "Active Cylinder Management." Reference symbols

[0239] 10 Actuator

[0240] 11L left coil unit

[0241] 11 R right coil unit

[0242] SRÜCK throwback signal

[0243] SAnst control signal

[0244] 12L left Hall sensor

[0245] 12R right Hall sensor

[0246] 12M medium Hall sensor

[0247] E Signal range “retracted home position”

[0248] EA signal range “up to half extended position”

[0249] A Signal range “extended setting position”

[0250] E' Signal range "not fully extended setting position"

[0251] 20L left cam piece

[0252] 20L-V cam contour full lift for one valve

[0253] 20L-N cam contour zero lift for one valve

[0254] 20R right cam piece

[0255] 20R-V cam contour full lift for one valve

[0256] 20R-N cam contour zero lift for one valve

[0257] 1L left actuator

[0258] 1R right actuator

[0259] M Center axis of the camshaft

[0260] XS shift gate

[0261] XN higher groove radially spaced from a central axis M

[0262] SN radially spaced deeper groove relative to a central axis M

[0263] E1 first end switching position

[0264] E2 second end switching position

Claims

Patent claims Method for detecting the position of at least one cam piece (20L, 20R) of a valve train for an internal combustion engine, wherein the valve train has at least one camshaft on which at least one cam piece (20L, 20R) is arranged in a rotationally fixed manner and axially displaceable between at least two axial positions, on which at least one cam piece is formed with a predeterminable cam contour (20L-V, 20L-N; 20R-V, 20R-N), wherein an axial displacement of the at least one cam piece (20L, 20R) takes place by means of an actuator (10) along the camshaft, wherein the at least one cam piece (20L, 20R) is assigned a switching gate (XS) designed as a groove, in which a first switching groove (XN) and a second switching groove (SN) are arranged, the groove depths of which in an intersection region in which the switching grooves (XN, XS) are located for axial Displacement of at least one cam piece (20L, 20R) spirally crossing, distinguishing each other,wherein the actuator (10) is arranged in an installation position with respect to the at least one cam piece (20L, 20R) which enables the at least one actuator (1L, 1R) to be reversibly extended out of the actuator (10) in the direction of the camshaft and retracted into the switching gate (XS), wherein the axial displacement of the at least one cam piece (20L, 20R) takes place by initiating a control signal (SAnst) by energizing a coil unit (11L, 11R) which is arranged stationary in the actuator (10), which drives an armature assembly connected to the at least one actuator (1L, 1R), whereupon the at least one actuator (1L, 1R) is extended out of the actuator (10) in the direction of the camshaft and is positioned in the switching gate (XS), characterized in that the detection of the position of the at least one actuator (1 L, 1 R) is carried out by at least one Hall sensor (12L, 12R; 12M),which is arranged in the actuator (10) for detecting the position of the at least one actuator (1 L, 1 R), wherein the Hall sensor (12L, 12R; 12M) provides a Hall sensor signal depending on the position of the at least one actuator (1 L, 1 R), from which it is concluded whether the at least one actuator (1 L, 1 R) is retracted into the first switching groove (XN) or second switching groove (SN) of the at least one cam piece (20L, 20R). Method according to claim 1, characterized in that the position-dependent Hall sensor signal for detecting the position of the at least one cam piece (20L, 20R) is combined with a return signal (SRÜCK) of the coil unit (11 L, 11 R), which radially displaces the at least one actuator (1 L, 1 R) from an initial position relative to the central axis (M) of the camshaft after it is energized, and generates the return signal (SRÜCK) upon the return displacement of the at least one actuator (1 L, 1 R) when the at least one actuator (1 L, 1 R) has returned to its initial position after its displacement, wherein, depending on the detected position-dependent Hall sensor signal and the return signal (SRÜCK), it is deduced from the position of the at least one actuator (20 L, 20 R) whether the at least one actuator (1 L, 1 R) is retracted into the first switching groove (XN) or second switching groove (SN) of the at least one cam piece (20 L, 20 R). Method according to claim 1, characterized in that the position-dependent Hall sensor signal is used to detect the position of the at least one cam piece (20 L,20R) is combined with the return signal (SRÜCK) of the coil unit (11 L, 11R) arranged in the actuator (10), which radially displaces the at least one actuator (1 L, 1R) from the starting position relative to the central axis (M) of the camshaft after it is energized, and generates the return signal (SRÜCK) upon the return displacement of the at least one actuator (1 L, 1R) when the at least one actuator (1 L, 1R) has returned to its starting position after its displacement, wherein the position-dependent Hall sensor signal and the return signal (SRÜCK) are further combined with a control signal (SAnst) which is generated by the coil unit (11 L, 11R) arranged in the actuator (10) after the at least one actuator (1 L, 1 R) is energized in order to radially displace it from the starting position relative to the central axis (M) of the camshaft. in order to move into at least one switching gate (XS) in the operating position,Depending on the detected position-dependent Hall sensor signal and the return signal (SRÜCK) and the control signal (SAnst), it is inferred from the position of the at least one actuator (1L, 1R) whether the at least one actuator (1L, 1R) is retracted into the first switching groove (XN) or second switching groove (SN) of the at least one cam piece (20L, 20R). Method according to claim 1, characterized in that the position-dependent Hall sensor signal for the first and second switching grooves (XN, SN) of the switching gate (XS) is provided in PWM signal ranges (E, EA, A, E') that are predeterminable and fixed with respect to the number, wherein the PWM signal ranges are assigned to stroke positions of the at least one actuator (1L, 1R).

5. Method according to claim 1, characterized in that two Hall sensors (12L, 12R) are arranged in the actuator (10) for the position detection of two actuators (1L, 1R), which are each assigned to a cam piece (20L, 20R), which detect the position of two actuators (1L, 1R) in the actuator (10) independently of one another and provide the position-dependent Hall sensor signal for each of the actuators (1L, 1R), wherein, depending on the detected position-dependent Hall sensor signal, it is deduced from the position of the two actuators (1L, 1R) whether the at least one actuator (1L, 1R) is retracted in the first switching groove (XN) or second switching groove (SN) of the at least one cam piece (20L, 20R), wherein the position detection of the two actuators (1L, 1R) is carried out simultaneously or with a time offset.

6. The method according to claim 1, characterized in that a single Hall sensor (12M) is arranged in the actuator (10) for detecting the position of two actuators (1L, 1R), each of which is assigned to a cam piece (20L, 20R), which detects the position of two actuators (1L, 1R) in the actuator (10) and provides the position-dependent Hall sensor signal for each of the actuators (1L, 1R), wherein, depending on the detected position-dependent Hall sensor signal, it is deduced from the position of the two actuators (1L, 1R) whether the at least one actuator (1L, 1R) is retracted in the first switching groove (XN) or second switching groove (SN) of the at least one cam piece (20L, 20R), wherein the position detection of the two actuators (1L, 1R) is carried out with a time offset.

7. Method according to claim 1, characterized in that when the internal combustion engine is started up, after a minimum speed of the internal combustion engine has been reached, an initialization circuit is carried out, whereby it is determined in which position the at least one cam piece (20L, 20R) is currently located by determining in which switching groove (XN; SN) of the switching gate (XS) the at least one actuator (1 L, 1R) engages.

8. Method according to claim 6, characterized in that the position of the at least one cam piece (20L, 20R) detected after the initialization circuit is stored and then the ongoing operation of the valve train is carried out. Valve train for an internal combustion engine for carrying out the method according to one or more of the preceding claims, wherein the valve train has at least one camshaft on which at least one cam piece (20L, 20R) is arranged in a rotationally fixed manner and axially displaceable between at least two axial positions, on which at least one cam piece is formed, at least one cam with a predeterminable cam contour (20L-V, 20L-N; 20R-V, 20R-N), wherein the at least one cam piece (20L, 20R) is assigned, by means of an actuator (10) along the camshaft, a switching gate (XS) designed as a groove, in which a first switching groove (XN) and a second switching groove (SN) are arranged, the groove depths of which differ from one another in an intersection region in which the switching grooves (XN, XS) cross one another in a spiral manner for the axial displacement of the at least one cam piece (20L, 20R), wherein the actuator (10) with respect to the at least a cam piece (20L, 20R) is arranged in an installation position,which enables the at least one actuator (1L, 1R) to be reversibly extended from the actuator (10) in the direction of the camshaft and retracted into the shift gate (XS), wherein a stationary coil unit (11L, 11R) is arranged in the actuator (10), which drives an armature assembly connected to the at least one actuator (1L, 1R), arranged in the actuator (10) and movable relative to the coil unit (111, 11R), characterized in that at least one Hall sensor (12L, 12R; 12M) is arranged in the actuator (10) for detecting the position of the at least one actuator (1L, 1R), which provides a Hall sensor signal depending on the position of the at least one actuator (1L, 1R). Valve train according to claim 9, characterized in that two actuators (1L, 1R) are arranged in the actuator (10), which are assigned to two cam pieces (20L, 20R) that are axially displaceable on a camshaft. Valve train according to claim 10, characterized in thatthat each actuator (1 L, 1 R) is assigned its own Hall sensor (12 L, 12 R), which is arranged in the actuator (10) essentially in the vertical longitudinal extent of the actuators (1 L, 1 R) with respect to the vertical longitudinal extent of the actuators (1 L, 1 R) in relation to the vertical longitudinal extent of the actuators (1 L, 1 R), which extends orthogonally to the central axis (M) of the camshaft, so that the Hall sensors (12 L, 12 R) provide their own position-dependent Hall sensor signals for each actuator (1 L, 1 R) simultaneously or with a time offset. Valve train according to claim 10, characterized in that a single Hall sensor (12M) is assigned to the two actuators (1L, 1R), which is arranged centrally in the actuator (10) with respect to a vertical longitudinal extent of the actuator (10), which extends orthogonally to a central axis (M) of the camshaft, so that the centrally arranged Hall sensor (12M) provides the position-dependent Hall sensor signal of one or the other actuator (1L, 1R) with a temporal offset. Valve train according to claim 9, characterized in that each of the two actuators (1L, 1R) is always assigned its own coil unit (11L, 11R) and its own armature assembly, wherein the respective coil unit (11L, 11R) drives the respective associated armature assembly.

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