Opening device for a motor vehicle door

Abstract

The invention relates to an opening device for a motor vehicle door, which is equipped with a plunger (3), an electric motor drive (4) for the plunger (3), and at least one sensor (8, 10) for detecting a positioning movement of the plunger (3). The sensor (8, 10) detects rotational movements of the electric motor drive (4) and converts these into an electrical signal that depends on the linear position of the plunger (3). For this purpose, the sensor (8, 10) is equipped with a signal transmitter (8) and a signal receiver (10). According to the invention, several signal transmitters (8) are provided circumferentially around a drive wheel (7) that interacts with the plunger (3), and these transmitters are moved past the stationary signal receiver (10) to generate the signal.

Description

[0001] The invention relates to an opening device for a motor vehicle door, comprising a plunger, an electric motor drive for the plunger, and at least one sensor for detecting an actuating movement of the plunger, wherein the sensor detects rotary movements of the electric motor drive and converts them into an electrical signal dependent on the linear position of the plunger, and is equipped with a signal transmitter and a signal receiver for this purpose.

[0002] Door openers for motor vehicles are increasingly used today. This is due to the fact that, in order to reduce aerodynamic drag, one or more vehicle doors are being designed or are being designed without an external handle. To still be able to open the vehicle door, it is first necessary to open one of the door leaves, which typically includes the vehicle lock. This is done by opening the corresponding vehicle lock or door lock.

[0003] This usually results in a gap between the door leaf and the surrounding vehicle body, which, however, is generally insufficient for the door leaf to swing open. Therefore, after the vehicle lock or door lock is opened, a corresponding prop-opening mechanism located inside the door leaf is typically energized. The prop-opening mechanism, with its extending plunger, then braces the door leaf against, for example, the surrounding vehicle body or a door frame. This brings the door leaf into a gap position relative to the surrounding vehicle body, allowing an operator to grasp the door leaf through the resulting gap and swing it open.

[0004] Of course, the reverse approach is also possible. In this case, the opening mechanism may be located inside the vehicle body or door frame, and the extension of the plunger then ensures that the door leaf is moved into the desired gap position. Either way, this typically eliminates the need for an external handle or door handle, as described in principle in DE 20 2017 104 635 U1. This patent concerns a powered door presenter for vehicle doors, equipped with a first electrically driven actuator and a second electrically driven actuator.

[0005] Another mounting device according to DE 10 2018 132 666 A1 aims to detect door movement using a sensor. For this purpose, at least one gearbox component is pivotably mounted, and the pivoting movement of the gearbox component can be detected by the sensor.

[0006] The generic and closest prior art according to DE 10 2021 107 177 A1 involves equipping the door system described therein with a power-operated presentation actuator. The presentation actuator is attached either to the vehicle body or to the vehicle door. Furthermore, the presentation actuator allows the vehicle door to be moved between a closed and a presented position.

[0007] Furthermore, an electronic control unit is implemented which actuates the power-operated presentation actuator depending on a command to release a lock and the vehicle's condition. For this purpose, the power-operated presentation actuator has an extendable element or plunger to move the vehicle door from a closed position to a presented position. This is also possible in response to a detection condition where the vehicle's condition prevents the normal opening of the vehicle door. A sensor, which may be an impact sensor, is provided for this purpose to determine the vehicle's condition.

[0008] The state of the art has generally proven effective, but still offers room for improvement. This can be attributed to the fact that, according to DE 10 2021 107 177 A1, the linear position of the extendable element can be deduced from the generic prior art by detecting rotations of an associated motor shaft with the aid of the sensor and evaluating the corresponding signals. That is, with the aid of the signal transmitter and signal receiver, the linear position of the plunger can be determined by the sensor indirectly or directly detecting rotational movements of the electric motor drive. For this purpose, the sensor in the known teaching is designed as a Hall effect sensor.

[0009] However, the current state of the art reaches its limits when the goal is not only to determine the linear position of the plunger, but also to derive protective or control functions from this. Indeed, with such positioning devices, it is crucial, among other things, to provide overload protection to prevent damage to the electric motor drive if, for example, the door leaf becomes blocked due to an accident or freezing. Furthermore, speed control of the plunger is often required, for instance, so that it operates at high speed at the beginning of its travel and then decreases towards the end. Currently, there are no convincing solutions for this.

[0010] Accordingly, the invention is based on the technical problem of further developing such a lifting device for a motor vehicle door in such a way that comprehensive safety monitoring is possible in order to avoid damage and at the same time offers the option of realizing different scenarios when the plunger is actuated.

[0011] To solve this technical problem, the invention proposes, starting from a generic mounting device for a motor vehicle door, that several signal transmitters are provided circumferentially on a drive wheel that interacts with the plunger, which are moved past the stationary signal receiver to generate the signal.

[0012] In contrast to the prior art according to the next patent application DE 10 2021 107 177 A1, the invention thus utilizes a plurality of signal transmitters. These signal transmitters are provided circumferentially around the drive wheel that interacts with the plunger. The drive wheel can drive the plunger. However, it is also possible for the drive wheel to simply follow the movement of the plunger.

[0013] In this latter case, the advantageous design is such that one drive wheel for the plunger is configured as the primary wheel for driving the plunger. A second drive wheel, on the other hand, serves as the secondary wheel, primarily carrying the signal transmitters. This means that, in this case, the second drive wheel, or secondary wheel, with its circumferentially arranged signal transmitters, provides little or no drive power to the plunger. The crucial factor is that the drive wheel, with its multiple circumferentially arranged signal transmitters, moves past the stationary signal receiver to generate a signal, allowing the movement of the plunger to be inferred from the signal sequence. For this purpose, the signal transmitters are typically arranged equidistantly around the circumference of the drive wheel.

[0014] This generates a signal sequence with consistent time intervals in the signal sensor when the plunger moves at a constant speed. From this signal sequence, the position of the plunger can be deduced. Additionally, it is also possible to deduce the speed of the plunger from this same sequence of signals.

[0015] Furthermore, the design is usually such that the signal receiver is not only capable of registering the signal generated by the moving signal transmitter, but can also detect both the proximity of the moving signal transmitter and its direction. In this way, the signal received by the receiver can also be evaluated to determine the direction in which the plunger is moving, for example, extending or retracting.

[0016] In general, the signal transmitter and receiver interact remotely. This enables particularly precise and wear-free operation, even over long timescales. While the transmitter and receiver could theoretically interact tactilely, contactless interaction is typically used.

[0017] The design of the signal transmitter(s) and the associated signal receiver can be implemented in various ways. For example, it is conceivable that the signal transmitter is an optical light element and the signal receiver is designed as a photoelectric sensor that registers the passing movement of the respective light source or light element.

[0018] Typically, the signal transmitter is designed as a permanent magnet and the signal receiver as at least a simple Hall sensor. This allows the individual signal transmitters or permanent magnets to be easily and equidistantly positioned around the circumference of the drive wheel. This is particularly advantageous if the plunger and / or the drive wheel are made of plastic. Furthermore, the choice of material (plastic) ensures that the electromagnetic interaction between the permanent magnets embedded around the circumference of the drive wheel and the Hall sensor is not disrupted.

[0019] The Hall sensor is at least a simple Hall sensor. It can also be designed as a dual Hall sensor. In this case, the dual Hall sensor is additionally able to detect the direction of rotation of the drive wheel and thus determine whether the associated signal transmitter or permanent magnet is moving past the signal receiver or dual Hall sensor in a first direction of rotation or in a second, opposite direction.

[0020] For reasons of particularly simple and precise guidance, the tappet is usually guided between two drive wheels. The design is further such that the two drive wheels are positioned opposite each other. In addition, the drive wheels engage with corresponding teeth on the tappet. It is particularly advantageous if one of the drive wheels is designed as the primary gear for driving the tappet.

[0021] For this purpose, the primary gear typically has circumferentially arranged teeth with a pronounced tooth height that engage in corresponding recesses in the associated teeth of the tappet. This means that the tooth height and the corresponding recess of the teeth are designed and adapted to each other with respect to the primary gear. In comparison, the second drive gear, or secondary gear, has a significantly lower tooth height compared to the primary gear. The recesses in the teeth belonging to the secondary gear are also designed with a correspondingly shallower depth. This is, of course, only an example and is by no means mandatory.

[0022] While in the above variant the primary wheel functions as the drive wheel for driving the plunger and the second secondary wheel largely carries the signal transmitters, the reverse is of course also possible. Likewise, it is within the scope of the invention that both wheels, i.e., the primary wheel as well as the secondary wheel, can be designed both as drive wheels and as carriers for the signal transmitters.

[0023] Typically, the signal sensor is connected to a control unit. The control unit can then deduce a multitude of parameters characterizing the plunger and its current position from the number of signals received by the sensor, their time intervals, and their sequence. In fact, based on these signals, the control unit can infer the plunger's position, direction of movement, speed, any blockages, etc., in order to define a start / stop position for the plunger, detect a load case, implement overload protection, or control the speed by actuating the drive. For example, the plunger's speed can be calculated from a temporal sequence of signals.If the speed signal is further differentiated over time in the control unit, it is possible to infer any accelerations or decelerations of the tappet. Decelerations of the tappet, in particular, can indicate blockages if a certain limit value predefined in the control unit is exceeded.

[0024] Furthermore, the control unit can deduce the direction of movement of the plunger from the signals, for example, by detecting that the permanent magnets, acting as signal generators, produce not a rectangular and symmetrical signal, but rather an asymmetrical one. The position of this asymmetry can then be evaluated to determine, for example, whether the secondary wheel with the signal generators is rotating clockwise or counterclockwise.

[0025] In this way, the control unit is able to detect a load case that might correspond to a blockage of the plunger. This also allows for overload protection, as the electric motor drive is switched off immediately or after a specific time period defined by the control unit in the event of a blockage. Finally, the control unit is also capable of controlling the speed of the plunger by activating the associated electric motor drive for the plunger.

[0026] Furthermore, the control unit can use this method to determine and define the start / stop position of the plunger. For example, the individual signals from the respective sensor can be counted to determine the plunger's travel distance in conjunction with the diameter of the corresponding wheel (primary and / or secondary wheel). This allows the desired start and stop positions to be defined and set.

[0027] This speed control, implemented using the control unit, works by first deducing the actual speed of the plunger from the signal sequence received by the sensor. This speed can then be increased, in the simplest case, by increasing the electrical power supplying the electric motor that drives the plunger. This can continue up to a certain speed limit, at which point the electrical power supply to the electric motor is reduced. This allows for speed control around the limit specified by the control unit.

[0028] Additionally, and with further advantageous embodiment, a start / stop sensor is usually provided for the plunger or rack. The signals from this start / stop sensor are also monitored and evaluated by the control unit. The start / stop sensor can be designed such that, for example, an embedded permanent magnet is provided at the end of the plunger. This magnet aligns with a corresponding Hall sensor when the plunger is fully retracted, thereby generating a stop signal in the control unit to switch off the electric motor drive of the plunger in the retracted position. This can also apply to the plunger's maximum extended position and be implemented in a comparable manner.

[0029] For optimal protection against environmental conditions, the plunger and one or both drive wheels are typically housed in a single main housing that contains the entire mounting device. This housing can be equipped with an opening for the plunger. Furthermore, the control unit, including one or more Hall sensors, can be housed in a separate control housing independent of the main housing. This control housing can be completely encapsulated, ensuring that neither the control unit nor the sensors are impaired in their operation.

[0030] Due to the long-range interaction between the signal transmitter and the signal receiver, it is possible to capture and register the signals through a wall of the plastic control housing using one or more signal receivers. This is because the electromagnetic interaction generally observed at this point easily penetrates the plastic of the control housing.

[0031] The result is a robustly constructed opening device for a motor vehicle door, featuring overload protection and reliable load case detection. Furthermore, undesired states and positions of the plunger can be easily identified because the control unit is constantly informed about the plunger's current position and speed, as well as any delays or blockages. Consequently, the plunger can also be subjected to speed control, for example, by starting its extension movement at a relatively high speed, which is then gradually reduced towards its extended end position, perhaps along a time-based ramp. Naturally, other speed control options are also conceivable and are covered by the invention.

[0032] The invention is explained in more detail below with reference to a drawing that merely illustrates an exemplary embodiment: The Fig. Figure 1 shows an overview of the inventive mounting device for a motor vehicle door and Fig. Two different time graphs of the captured signal.

[0033] One can recognize from the Fig. 1. First and foremost, and quite fundamentally, a support device for a motor vehicle door, which is only indicated here and has a door leaf 1. The motor vehicle door may be a side door. According to the exemplary embodiment, the support device is arranged inside the door leaf 1. In principle, however, the support device can also be located inside a door leaf 1, which is also shown in the illustration. Fig. 1. The vehicle body 2 is to be placed on the recognizable vehicle body.

[0034] As a rule, the opening mechanism inside the door leaf 1 ensures that, with the aid of an extendable plunger 3 as an essential structural element, the door leaf 1 can be extended relative to the indicated vehicle body 2 in order to create a space within the Fig. The system is designed to adjust the indicated gap S between the door leaf 1 (or the vehicle door) and the vehicle body 2. An operator can grasp the door leaf 1 through this gap S and swing it fully open.

[0035] For this purpose, it is generally necessary to first open a vehicle lock (not shown) with which the door leaf 1 is equipped and which locks against the vehicle body 2 when the vehicle door is closed. Opening the vehicle lock (not shown) can be done by remote control, a question-and-answer dialogue between a user-side transponder and a vehicle-side control unit, or in any other way.

[0036] Since, with the vehicle lock open, the door leaf 1 is only slightly ajar relative to the vehicle body 2, corresponding to a gap S through which an operator cannot fully open the door leaf 1, the opening device ensures that the plunger 3 is extended after the vehicle lock or vehicle door lock is opened. The extended plunger 3 then causes the door leaf 1 to increasingly brace itself against the vehicle body 2 and swing outwards relative to it until the gap S is reached. Now, an operator or user can grasp the door leaf 1 through the gap S and fully open it.

[0037] To extend the plunger 3, an electric motor drive 4 is provided for the plunger 3. According to the exemplary embodiment, the electric motor drive 4 is designed as an electric motor with an optional downstream gearbox. In this embodiment, the electric motor drive 4 acts on a drive wheel 5 or primary wheel 5, which drives the plunger 3. For this purpose, the primary wheel 5 is equipped with circumferential teeth that engage with corresponding teeth 6 on the plunger 3.

[0038] Furthermore, according to the exemplary embodiment, a further drive wheel 7 is implemented, which is designed as a secondary wheel 7 and, according to the invention, carries several signal transmitters 8 circumferentially. In this example, the signal transmitters 8 are arranged in the teeth of the drive wheel or secondary wheel 7. The secondary wheel 7 also engages with its teeth in a corresponding toothing 9 on the plunger 3. The toothing of the wheels 5 and 7 is located opposite each other along the longitudinal extent of the plunger 3. Both the primary wheel 5 and the secondary wheel 7 can also function as drive wheels 5 and 7, respectively, as well as carriers for the signal transmitters 8. In this case, the functions of the primary wheel 5 and the secondary wheel 7 coincide, and both wheels 5 and 7 can fulfill the function of both the drive and the function of carrying the signal transmitters 8.

[0039] It can be seen that, according to the exemplary embodiment, the primary gear 5, which is set in rotation by means of the electric motor drive 4, has a significantly greater tooth height than the tooth height of the secondary gear 7. The same applies to the gearing 6, which is equipped with corresponding tooth grooves of greater depth for the primary gear 5 compared to the gearing 9, which has a correspondingly shallower tooth groove depth for the engagement of the teeth of the secondary gear 7. This is also only an example and should in no way be understood as a limitation.

[0040] In any case, a sensor 8, 10 is provided at this point, which can be used to detect the positioning movement of the plunger 3. For this purpose, the sensor 8, 10 detects rotary movements of the electric motor drive 4, indirectly, because rotary movements of the electric motor drive 4 correspond to a linear movement of the plunger 3, which in turn causes a rotary movement of the secondary wheel 7 with its signal transmitters 8. The rotary movement of the secondary wheel 7 with the circumferentially arranged signal transmitters 8 then corresponds to an electrical signal from the associated signal receiver 10. This allows an electrical signal dependent on the linear position of the plunger 3 to be observed at the output of the signal receiver 10, and thus of the sensor 8, 10. According to the exemplary embodiment, this signal is detected by means of a control unit 11, to which the signal receiver 10 is connected as a component of the sensor 8, 10.

[0041] As already explained, according to the exemplary embodiment and the invention, several signal transmitters 8 are provided circumferentially of the drive wheel 7, which interacts with the plunger 3, and specifically of the secondary wheel 7. The individual signal transmitters 8 circumferentially of the secondary wheel 7 are moved past the stationary signal receiver 10 to generate the signal. As a result, more or less rectangular signals are generated in the signal receiver 10 at a specific time interval T1 when the plunger 3 is moving at a constant speed, as shown in the uppermost illustration in the Fig. Figure 2 illustrates this. This corresponds to a low speed of the plunger 3, as will be explained in more detail below. However, if the plunger 3 moves at a higher speed, a smaller time interval T2 is observed between the individual signal pulses, as shown in the middle illustration in Figure 2. Fig. 2 is shown. In this case, the plunger 3 completes a greater speed compared to that shown in the upper diagram of the Fig. 2. Situation shown.

[0042] According to the exemplary embodiment, the signal transmitters 8 are arranged equidistantly around the circumference of the drive wheel 7, so that in the two diagrams in the Fig. 2. An equal time interval T1 at low speed and T2 at higher speed is observed between the individual signal pulses. Furthermore, the design according to the exemplary embodiment is such that the signal receiver 10 detects not only the proximity of the moving signal transmitter 8, but also its direction. For this purpose, it is possible that the respective signal transmitter 8 does not generate strictly rectangular signals in the signal receiver 10, but rather that the rectangular signals are equipped with an asymmetry. If the asymmetry is formed on the rising or falling edge of the rectangular signal, the direction of movement of the drive wheel 7 (clockwise or counterclockwise) can be deduced. This is not shown in detail.

[0043] This enables the signal sensor 10, and with it the control unit 11 that evaluates its signals, to detect the direction of the ram's movement 3, specifically whether it is extending or retracting. The diagram in the Fig. 2 in the upper illustration shows an extension movement of the plunger 3 at a low speed, whereas the representation shown in the middle illustration corresponds to a retraction process of the plunger 3 at a higher speed.

[0044] Such a differentiation with regard to speeds is possible according to the invention because the signal sensor 10 can detect the direction of the plunger 3 and, conversely, the electromechanical drive 4 connected to it is also actuated accordingly by means of the control unit 11. In fact, a corresponding in the Fig. 1. The extension movement in direction A, represented by a right-pointing arrow, causes the drive wheel 5 or primary wheel 5 to perform a rotational movement in the indicated counterclockwise direction. If, on the other hand, the plunger 3 is to be retracted in the opposite direction to this in the retraction direction E, and in this context the movement shown in the middle illustration of the Fig. To achieve the higher speed shown in section 2, the drive wheel or primary wheel 5 is driven clockwise.

[0045] In either case, the design is such that the respective signal transmitter 8 and the signal receiver 10 interact remotely. For this purpose, the signal transmitter 8 is designed as a permanent magnet 8 in the exemplary embodiment. The signal receiver 10, on the other hand, is at least a simple Hall sensor 10. In the exemplary embodiment, a double Hall sensor 10 is implemented, with which the direction of the drive wheel 7 or secondary wheel 7 can be determined, namely clockwise or counterclockwise. If the secondary wheel 7 moves clockwise, this corresponds to the extension movement A of the plunger 3, and a counterclockwise movement of the secondary wheel 7 corresponds to the plunger 3 moving in the retraction direction E.

[0046] To ensure that the interaction between the signal transmitter 8 and the associated signal receiver 10 is not disrupted, the drive wheel 7 or secondary wheel 7 is made of plastic. The signal transmitters or permanent magnets 8 may be embedded in the drive wheel or secondary wheel 7 using a plastic injection molding process. In contrast, it has proven advantageous for the plunger 3 and the primary wheel 5 to be made of metal. Of course, the drive wheel or primary wheel 5 and the plunger 3 could also be made of plastic.

[0047] The plunger 3 is guided between the two drive wheels 5 and 7. The two drive wheels 5 and 7 are mostly diametrically opposed to each other and engage with their respective gear teeth 6 and 9.

[0048] As already explained, the signal receiver or Hall sensor 10 is connected to the control unit 11. This also applies to an additional start / stop sensor 12, 13 for the plunger 3. This start / stop sensor 12, 13 for the plunger 3 consists of a permanent magnet 13 at one end of the plunger 3 and another associated Hall sensor 12. The Hall sensor 12 is also connected to the control unit 11. As soon as the plunger 3 reaches its position in the Fig. Once the plunger 3 has reached its fully retracted position (as shown in Figure 1), the permanent magnet 13, embedded at the end of the plunger 3, enters the field of action of the Hall sensor 12. Consequently, a corresponding signal is transmitted to the control unit 11, which then switches off the electric motor drive 4 connected to the control unit 11. Not shown is a further signal line to the control unit 11, which informs the control unit 11, for example, that a vehicle lock (not shown) on the door leaf 1 has been opened and, consequently, the drive 4 can be activated to execute the extension movement A of the plunger 3.

[0049] Finally, it can be seen that the entire installation device is housed in a casing 14, which is positioned inside the door leaf 1 as the main casing. The casing 14 is equipped with a through-opening 15 for the plunger 3, which extends and retracts into it. Additionally, a control casing 16 is provided, which is completely enclosed and houses the two Hall sensors or signal transducers 10 and 12, as well as the control unit 11. This ensures that the particularly sensitive electronic components are further protected from potential environmental influences by being located inside the casing 14.

[0050] Based on the third lower representation in the Fig. As can be seen in Figure 2, the control unit 11, based on the signals from the signal receiver 10, is not only able to determine their time interval T1, T2 and their sequence in order to deduce an extension movement A and a retraction movement or the retraction direction E. Rather, the time interval T1 and T2 also allows conclusions to be drawn about a low speed in the case of a large time interval T1 and a high speed in the case of a correspondingly small time interval T2, as already described in the introduction.

[0051] Additionally, control unit 11 can detect any blockages. This is shown in the lower diagram. Fig.Figure 2 shows that the temporal sequence of the individual signals from the signal generator 8 exhibits a decreasing time interval, indicating an increasing blockage of the plunger 3. Depending on how much the time interval between the individual signal pulses decreases, the control unit 11 can decide whether the observed blockage necessitates overload protection. If overload protection is required, the control unit 11 ensures that the electric motor drive 4 is immediately switched off. Furthermore, speed control by actuating the drive 4 using the control unit 11 is possible and can be implemented as described in the introduction.In this case, the control unit 11 is used to change the time interval between the signal pulses T1 and T2 until a time interval corresponding to the desired speed is reached. Around this predetermined setpoint, the control unit 11 can then regulate the system such that if the time interval is too long, the electrical power used to control the electric motor drive 4 is increased, and if the time interval is too short, it is reduced accordingly. Reference symbol list 1 door leaf 2 Motor vehicle body 3 pestles 4 electromagnetic drive 5 Drive wheel / primary wheel 6 gear teeth 7 Drive wheel / Secondary wheel 8 signal transmitters 9 gear teeth 10 Hall sensor 11 Control unit 12 Start / Stop Sensor 13 Permanent magnet 14 Housing or main housing 15 Passage opening 16 control housings QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 20 2017 104 635 U1

[0004] DE 10 2018 132 666 A1

[0005] DE 10 2021 107 177 A1 [0006, 0008, 0012]

Claims

Opening device for a motor vehicle door, comprising a plunger (3), further comprising an electric motor drive (4) for the plunger (3), and comprising at least one sensor (8, 10) for detecting an actuating movement of the plunger (3), wherein the sensor (8, 10) detects rotary movements of the electric motor drive (4) and converts them into an electrical signal dependent on the linear position of the plunger (3), and is equipped for this purpose with at least one signal transmitter (8) and a signal receiver (10), characterized in that several signal transmitters (8) are provided circumferentially on a drive wheel (7) that interacts with the plunger (3), which are moved past the stationary signal receiver (10) to generate the signal. Device according to claim 1, characterized in that the signal transmitters (8) are arranged equidistantly around the circumference of the drive wheel (7). Device according to claim 1 or 2, characterized in that the signal receiver (10) detects both the proximity of the passing signal transmitter (8) and its direction. Device according to one of claims 1 to 3, characterized in that the respective signal transmitter (8) and the signal receiver (10) interact with each other remotely. Device according to one of claims 1 to 4, characterized in that the respective signal transmitter (8) is designed as a permanent magnet (8) and the signal receiver (10) as at least a simple Hall sensor (10). Device according to one of claims 1 to 5, characterized in that the plunger (3) and / or the drive wheel (7) are made of plastic. Device according to one of claims 1 to 6, characterized in that the plunger (3) is guided between two drive wheels (5, 7) which are opposite each other and engage in their respective associated teeth (6, 9). Device according to claim 7, characterized in that one drive wheel (5) is designed as a primary wheel (5) for driving the plunger (3), while the other, second drive wheel (7) as a secondary wheel (7) largely carries the signal transmitters (8) or both wheels (5, 7) function both as drive wheels (5, 7) and as carriers for the signal transmitters (8). Device according to one of claims 1 to 8, characterized in that the signal receiver (10) is connected to a control unit (11) which infers from the number of signals, their time interval and their sequence the position of the plunger (3), its direction of movement, its speed, any blockages, etc., in order to define, for example, a start / stop position of the plunger (3), to detect a load case if necessary, to implement overload protection or to carry out speed control by controlling the drive (4). Device according to one of claims 1 to 9, characterized in that a start / stop sensor (12, 13) is additionally provided for the plunger (3).

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