Longitudinal adjustment device for vehicle seat

Abstract

The invention relates to a longitudinal adjustment device (1) for a vehicle seat (2), comprising a first adjustment element (11A), which is guided on a first rail (10A), a second adjustment element (11B), which is guided on a second rail (10B), a first drive device (12A), by means of which the first adjustment element (11A) can be adjusted along the first rail (10A), and a second drive device (12B), by means of which the second adjustment element (11B) can be adjusted along the second rail (10B), wherein the control unit (120A) of the first driving device (12A) is in communication connection with the control unit (120B) of the second driving device (12B).

Description

[0001] manual

[0002] The present invention relates to a longitudinal adjustment device for a vehicle seat and a vehicle seat having such a longitudinal adjustment device.

[0003] In the case of vehicle seats, longitudinal adjustment devices are typically used to adjust the seat portion and backrest along the longitudinal direction of the vehicle, for example, to provide more or less legroom for the seat occupant as needed. Electric longitudinal adjustment devices offer great convenience, where the adjustment is achieved by an electric motor. A longitudinal adjustment device typically has at least two tracks spaced apart in the lateral direction, each track having an adjustment element. The adjustment element can be configured as a seat track that engages with the corresponding track. In practice, the electric motor is usually arranged, for example, in the free space between the two tracks, and in each case operably connected to the adjustment element via a shaft, allowing the motor to adjust both adjustment elements along the tracks.

[0004] However, in some applications, it is desirable to maintain free structural space between the tracks; or the space between the tracks may be blocked by fixed components. In both cases, mechanical coupling of a single motor with two regulating elements is usually not achievable, or can only be achieved at a very high cost.

[0005] Therefore, in some cases, it may be advantageous to provide two motors, each for one of the two regulating elements.

[0006] DE 198 60 910 B4 describes a longitudinal adjustment device with two independent drive units, each with a drive motor. To synchronize the rotational movements of the two drive motors, the application suggests using a mechanical synchronization shaft between them; however, this offers little advantage over driving only by a single common motor. Alternatively, the application suggests providing a control unit electrically connected to the two drive motors and a corresponding device for detecting their relative position. However, this typically increases wiring costs.

[0007] The solution in DE 10 2008 007 267 B4 has similar drawbacks. There, two motors are connected in series or parallel and controlled by a switch.

[0008] The purpose of this invention is to provide an improved longitudinal adjustment device.

[0009] This objective is achieved by a subject matter having the features of claim 1.

[0010] According to the present invention, a longitudinal adjustment device for a vehicle seat includes: a first adjustment element guided on a first track, a second adjustment element guided on a second track, a first drive unit by means of which the first adjustment element can be adjusted along the first track, and a second drive unit by means of which the second adjustment element can be adjusted along the second track. For this purpose, a control unit for the first drive unit and a control unit for the second drive unit are provided in communicative connection.

[0011] By providing two independent drive units, one for the first adjustment element and one for the second adjustment element, the space between the tracks can be occupied in other ways. Furthermore, since each of the two drive units is controlled by its own control unit, the wiring for the communication connection between the control units can be particularly flexible to suit specific applications and can be implemented simply using, for example, a few wires with small cross-sections or optical conductors. Alternatively, the communication connection can even be performed wirelessly. Moreover, existing communication infrastructure within the vehicle can be used, making particularly simple connections possible.

[0012] The control unit of the second drive unit can be configured to synchronize the movement of the second adjusting element with the movement of the first adjusting element via a communication connection. Therefore, the first drive unit provides the movement, and the second drive unit takes over that movement. Thus, the first drive unit operates as the "master" and the second drive unit operates as the "slave." The second drive unit follows the control of the first drive unit.

[0013] Optionally, the control unit of the first drive unit is configured to determine the position of the first adjusting element along the first track and transmit the position to the control unit of the second drive unit. This enables efficient control and communication.

[0014] The control unit of the second drive unit controls the drive motor of the second drive unit, for example, based on the position transmitted by the control unit of the first drive unit. This makes precise control possible.

[0015] For example, the control unit of the second drive unit is configured to calculate the set speed of the drive motor of the second drive unit based on the position transmitted by the control unit of the first drive unit. Based on this set speed, the drive motor of the second drive unit can be adjusted. This allows the second adjustment element to quickly and accurately follow the first adjustment element simultaneously.

[0016] Furthermore, the control unit of the second drive unit can be configured to use the position transmitted by the control unit of the first drive unit as the set position of the second adjustment element along the second track. Therefore, the second control unit moves to the last communicated position in each case. This allows for precise and robust control.

[0017] Optionally, the control unit of the second drive unit is configured to calculate the pulse width modulation signal (e.g., based on a calculated set speed). Thus, for example, a brushless DC motor (BLDC motor) can be controlled as a drive motor.

[0018] Optionally, the control unit of the first drive unit communicates with the control unit of the second drive unit via a bus system. This makes a particularly simple design possible because such bus systems already exist in many cases and can typically be connected over short distances.

[0019] For example, the bus system is constructed as a LIN bus system (Local Interconnect Network). This makes a particularly simple design possible. Alternatively, a CAN bus can also be conceived as a bus system, for example. Bus systems based on CAN FD, FlexRay, Ethernet, K-line, or MOST are also conceivable. The described longitudinal adjustment device allows for electronic synchronization via a low-frequency bus system. In this case, an existing bus system can be used, making particularly low overhead possible.

[0020] The control unit of the first drive unit can communicate with the control unit of the second drive unit via a gateway. For example, the gateway can establish communication between the control units. For instance, the gateway can provide a clock for the communication. The gateway can be a LIN bus command generator, and the control unit can be implemented as a simple LIN bus responder.

[0021] The control unit of the first drive unit can communicate with the control unit of the second drive unit in one-way or two-way communication. In the case of a two-way communication connection, for example, the control unit of the second drive unit can convey feedback to the control unit of the first drive unit regarding the executed adjustment movements and / or errors. Therefore, functionality and robustness can be further improved.

[0022] Optionally, the control unit of the first drive unit is configured to transmit data frames containing control data to the control unit of the second drive unit at time intervals. Therefore, the control unit of the second drive unit can progressively simulate the motion controlled by the control unit of the first drive unit.

[0023] In the improved solution, the control unit of the second drive device is configured to interpolate the control data contained therein during the time interval between two consecutive data frames. In this way, particularly uniform control can be achieved even under high utilization of the communication channel between control units (e.g., a LIN bus system).

[0024] The control unit of the second drive unit can be configured to detect fault conditions and communicate with the control unit of the first drive unit. This enables exceptionally high safety and robustness of the longitudinal adjustment device.

[0025] According to one aspect, a vehicle seat is provided, including a seat portion, a backrest, and a longitudinal adjustment device according to any design described herein, wherein at least the seat portion (particularly the seat portion and the backrest) is supported on an adjustment element of the longitudinal adjustment device.

[0026] The accompanying figures illustrate possible variations of the proposed solution as examples.

[0027] It is shown that:

[0028] Figure 1 A vehicle with longitudinally adjustable seats is shown;

[0029] Figure 2 It shows according to Figure 1 The longitudinal adjustment equipment for the vehicle seats;

[0030] Figure 3 It shows according to Figure 2 The control units of the longitudinal adjustment equipment are interconnected with each other;

[0031] Figure 4 It shows according to Figure 2 The adjustment of the drive motor of the longitudinal adjustment device; and

[0032] Figure 5 It shows the bus system according to Figure 3 A sequence of messages sent between the control units of the longitudinal adjustment device.

[0033] Figure 1 An example is shown of a vehicle 3 in the form of a passenger car. Vehicle 3 includes multiple vehicle seats 2, one of which is in… Figure 1 As shown in the image.

[0034] The vehicle seat 2 includes a seat portion 20 and a backrest 21. In the example shown, the backrest 21 is pivotally supported on the seat portion 20. Furthermore, the vehicle seat 2 includes a longitudinal adjustment device 1.

[0035] The seat portion 20 and the backrest 21 can be moved along the longitudinal axis via the longitudinal adjustment device 1. For this purpose, the longitudinal adjustment device 1 includes two tracks 10A and 10B, wherein the first track 10A is in... Figure 1 As can be seen in the side view. The second track 10B extends parallel to the first track 10A (and is spaced apart from the first track 10A), for example, see reference to Figure 2 As can be seen.

[0036] Tracks 10A and 10B are fastened to the lower structure 31 of the vehicle 3. The lower structure 31 represents a part of the vehicle body of the vehicle 3, or alternatively, is fastened thereto. Adjusting elements 11A and 11B are displaceably guided along each track 10A and 10B. Thus, a first adjusting element 11A is guided on the first track 10A, and a second adjusting element 11B is guided on the second track 10B. Figure 1 In the side view, the first adjusting element 11A can be seen, while Figure 2 The second adjustment element 11B can be seen again in the middle.

[0037] In this case, adjusting elements 11A and 11B have track-like portions that engage with corresponding tracks 10A and 10B for longitudinal displacement, such as... Figure 2 As shown. The support portion of each adjusting element 11A, 11B is securely connected to the corresponding track-like portion. In this case, the two support portions of adjusting elements 11A, 11B extend through the vehicle floor 30. The vehicle floor 30 includes, for example, carpet. In this way, tracks 10A, 10B can be arranged below the vehicle floor 30, so they are not visible to passengers. This structure facilitates cleaning of the vehicle 3 and also facilitates the formation of particularly long tracks 10A, 10B. Therefore, a particularly wide adjustment path is possible, which allows for a great degree of freedom when using the vehicle interior.

[0038] In the example shown, the seat portion 20 is supported on adjusting elements 11A and 11B by (optional) height-adjustable devices. The seat portion 20 is assembled on adjusting elements 11A and 11B (height adjustable). The seat portion 20 can be fastened to adjusting elements 11A and 11B.

[0039] Figure 2 A longitudinal adjustment device 1 is shown, extending along the longitudinal range of tracks 10A and 10B. Figure 2 It can also be seen that the longitudinal adjustment device 1 further includes a first drive device 12A, by means of which the first adjustment element 11A can be adjusted along the first track 10A, and a second drive device 12B, by means of which the second adjustment element 11B can be adjusted along the second track 10B.

[0040] Each of the drive units 12A and 12B includes its own drive motor 121. Thus, the longitudinal adjustment device 1 has two drive motors 121, which may optionally have the same structure, as shown in the example.

[0041] Each drive motor 121 (via a gearbox) drives a shaft 122. The corresponding shaft 122 sequentially drives a worm gear 123 that meshes with a corresponding spindle nut 124. In the example shown, the spindle nuts 124 are rotatably supported on corresponding adjusting elements 11A and 11B, respectively, and engage with the spindle 124, which are arranged and fixed relative to the corresponding tracks 10A and 10B. Therefore, activation of the drive motor 121 of the first drive unit 12A causes the spindle nut 124 to tighten along the corresponding spindle 124. In this case, the spindle nut 124 carries the first adjusting element 11A. Similarly, activation of the drive motor 121 of the first drive unit 12A causes the corresponding spindle nut 124 to tighten along the associated spindle 124, wherein the spindle nut 124 carries the second adjusting element 11B. It should be noted that this arrangement is merely exemplary. Alternatively, for example, in each case, the worm gear 123 can mesh with a gear fastened to the spindle, which is rotatably supported relative to the corresponding tracks 10A, 10B, such that the spindle will be rotated by means of a fixed drive motor. Then, the corresponding spindle nut, which engages with the corresponding spindle, will be fastened to the corresponding adjusting element 11A, 11B.

[0042] The drive motor 121 of the first drive device 12A is located near the first adjusting element 11A (and the first track 10A), and the drive motor 121 of the second drive device 12B is located near the second adjusting element 11B (and the second track 10B). The drive motor 121 of the first drive device 12A is closer to the first adjusting element 11A (and the first track 10A) than the drive motor 121 of the second drive device 12B. The drive motor 121 of the second drive device 12B is closer to the second adjusting element 11B (and the second track 10B) than the drive motor 121 of the first drive device 12A.

[0043] By providing two independent drive motors 121, torque transmission is not required between the drive units 12A, 12B and the regulating elements 11A, 11B. Therefore, with the described arrangement, the structural space between the two tracks 10A, 10B is free and can be occupied in other ways, such as by a portion of the traction battery, a fan channel, etc. Figure 2 Obstacle H is schematically shown as its representative. Conversely, the mechanical coupling of the drive of adjusting elements 11A, 11B must move along the longitudinal axis in the region of obstacle H.

[0044] To enable the coordinated movement of the two regulating elements 11A and 11B, although there is no mechanical torque transmission, the control unit 120A of the first drive unit 12A (directly or indirectly, e.g., via a gateway) is communicatively connected to the control unit 120B of the second drive unit 12B. The two control units 120A and 120B can exchange data with each other, particularly bidirectionally in this example. The control unit 120A of the first drive unit 12A is configured to send data to the control unit 120B of the second drive unit 12B, and the second drive unit 12B is configured to receive and process the data. In the described example, the control unit 120B of the second drive unit 12B is also configured to send data to the control unit 120A of the first drive unit 12A, and the first drive unit 12A is similarly configured to receive and process the data sent to it.

[0045] For this purpose, two control units 120A and 120B are connected to a communication system. Typically, wired, optical, or wireless communication systems are conceivable. In the example shown, control units 120A and 120B are connected to a common bus system 13.

[0046] In this configuration, bus system 13 is a LIN bus. LIN buses have a simple structure, are relatively inexpensive, and are already present in many vehicles. Therefore, the two control units 120A and 120B can communicate with each other in a particularly simple manner. The two control units 120A and 120B communicate via a predefined transmission protocol. In this case, the two control units 120A and 120B exchange data packets with each other in the form of data frames. Depending on the configuration of the communication system, data packets can be exchanged directly between the two control units 120A and 120B. In this example of a bus system 13 configured as a LIN bus, a gateway 130 is provided in bus system 13 that facilitates the exchange of data frames between the two control units 120A and 120B.

[0047] To synchronize the movements of the two regulating elements 11A and 11B, a master-slave principle is employed. According to this principle, one of the control units 120A and 120B (i.e., control unit 120A of the first drive device 12A) predetermines the adjustment, while the other of the two control units 120A and 120B (i.e., control unit 120B of the second drive device 12B) follows that adjustment. Therefore, control unit 120B of the second drive device 12B is configured to synchronize the movement of the second regulating element 11B with the movement of the first regulating element 11A via a communication connection through bus system 13.

[0048] To this end, the control unit 120A of the first drive device 12A is configured to determine the position of the first adjusting element 11A along the first track 10A and transmit this position to the control unit 120B of the second drive device 12B via data frames. For the most uniform possible motion, the control unit 120A of the first drive device 12A is configured, for example, to transmit multiple consecutive data frames with corresponding updated positions to the control unit 120B of the second drive device 12B in a periodic sequence.

[0049] Because the control unit 120B of the second drive unit 12B responds to the position of the first adjustment element 11A, the second adjustment element 11B follows the first adjustment element 11A, while the first adjustment element 11A (slightly) leads. Due to the rapid communication via the bus system 13, communication occurs with low latency. Therefore, communication of data packets from the control unit 120A of the first drive unit 12A to the control unit 120B of the second drive unit 12B occurs within less than 100 ms, particularly less than 40 ms, and typically within 20 ms. Therefore, the seat occupant typically does not perceive the positional difference, and it can be compensated for by the elasticity of the seat portion 20 of the vehicle seat 2 without requiring separate intervention. However, if an alternative communication system with relatively large latency were to be used, it would be conceivable to use one or more elastic compensation elements, which could, for example, be assembled between the adjustment elements 11A, 11B and the seat portion 20.

[0050] Figure 3 The communication between the two control units 120A and 120B described is shown and will now be referred to.

[0051] First, a control command B is issued to the control unit 120A of the first drive unit 12A. This can be achieved in a particularly simple way by actuating a switch; for example, the switch is actuated whenever adjustment is needed. Then, the control unit 120A controls the drive motor 121 of the first drive unit 12A to achieve adjustment in the direction corresponding to the switch.

[0052] As an alternative (or supplement) to the control command B via the switch, a control command with data frame 400 can be transmitted to control unit 120A via bus system 13. Thus, for example, an external control device can be notified to approach a certain location, such as a preset location. Then, control unit 120A of the first drive unit 12A moves the first adjusting element 11A to that location. The transmission of data frame 400 occurs, for example, via gateway 130 (optionally via another path).

[0053] To synchronize the movements of the two regulating elements 11A and 11B, the control unit 120A of the first drive unit 12A (at least during the movement of the first regulating part 11A) sends data frames 401 containing control data to the control unit 120B of the second drive unit 12B at regular time intervals (via gateway 130). The data frames include digital data. The control units 120A and 120B communicate with each other digitally. Data frames 401 include a predetermined number of bits. In this example, each data frame 401 has (but is not mandatory) a header and a data portion. For example, the data portion has a size of 8 bytes (or at most 8 bytes).

[0054] Each data frame 401 includes the actual position of the first adjustment section 11A and / or the actual adjustment speed of the first adjustment section 11A (e.g., in the form of the current rotational speed) and / or the control mode and / or possible fault conditions. In particular, data frame 401 may include all of these data in each case.

[0055] The control unit 120A of the first drive unit 12A detects the actual position of the first adjustment section 11A, for example by counting the number of revolutions of the movable part of the first drive unit 12A, optionally using a provided position sensor, and / or the actual adjustment speed of the first adjustment section 11A (e.g., in the form of a currently set rotational speed) and / or the currently set control mode and / or possible fault conditions, and writes this data into a data frame 401, which sends it to the control unit 120B of the second drive unit 12B. For example, the control mode may indicate stationary, speed control adjustment, or position control adjustment. Furthermore, the control mode may indicate a standardized stroke in which the vehicle travels to a stop.

[0056] The control unit 120B of the second drive unit 12B receives and processes data frame 401, which will be referred to below. Figure 4 To explain in more detail.

[0057] After receiving and processing the corresponding data frame 401, the control unit 120B of the second drive unit 12B sends a data frame 402 to the control unit 120A of the first drive unit 12A. Each data frame 402 includes the actual position of the second adjustment section 11B and / or the actual adjustment speed of the second adjustment section 11B (e.g., in the form of the current rotational speed) and / or the set control mode and / or possible fault conditions. Specifically, the data frame 402 may include all of these data in each case. The data frame 402 is specifically used as feedback. Based on the feedback, the control unit 120A of the first drive unit 12A can identify whether the movements of the two adjustment elements 11A, 11B are synchronized (within the communication delay range of the control units 120A, 120B). Therefore, the control unit 120A of the first drive unit 12A can detect a fault and react accordingly, such as stopping the fault. However, this feedback is optional, and unidirectional communication only from the control unit 120A of the first drive unit 12A to the control unit 120B of the second drive unit 12B can also be provided.

[0058] Figure 4 An exemplary control of synchronized motion by a control unit 120B of a second drive unit 12B is shown. In this case, a portion of the control is implemented by software SW; however, this is merely exemplary. The control unit 120B includes a memory storing the software SW and a processor executing the software SW.

[0059] Once data frame 401 arrives, control unit 120B reads the current position of the first adjustment element 11A POS_1 stored therein. This is then passed to position controller 500, which also receives the current position of the second adjustment element 11B POS_2. The current position of the second adjustment element 11B POS_2 is measured by control unit 120B, for example, just as control unit 120A of the first drive unit 12A measures the current position of the first adjustment element 11A (see above). Based on these two positions POS_1 and POS_2, position controller 500 calculates the set rotational speed. If the two positions POS_1 and POS_2 are the same, the set rotational speed is, for example, equal to zero. The greater the difference between the two positions POS_1 and POS_2, the greater the set rotational speed.

[0060] The position controller 500 provides a set speed to the speed controller 501. The latter also receives the current (actual) speed DZ of the second drive unit 12B. Based on the set speed and the current speed DZ, the speed controller 501 calculates a set current intensity and provides it to the current intensity controller 502. The latter also receives the current (actual) current intensity I of the second drive unit 12B. Based on the set current intensity and the current current intensity, the current intensity controller 502 calculates a pulse width modulation (PWM) signal, which is transmitted to the hardware of the second drive unit 12B to cause the drive motor 121 to perform the corresponding movement. Alternatively, in an intermediate step, the voltage can be calculated first based on the current intensity.

[0061] In this case, the drive motor 121 is a brushless DC motor (BLDC motor). However, it should be noted that other types of motors can also be used; then, they can be configured differently according to the control of the position controller 500. Furthermore, it should be noted that position control is not necessarily required, but speed synchronization can also be performed directly. However, position control allows for particularly precise synchronization, where only the delay-related offset of the regulating elements 11A and 11B is negligible.

[0062] Figure 5 The possible communication flow during adjustment is illustrated. First, data frame 400, along with a control command, is transmitted from gateway 130 to control unit 120A of the first drive unit 12A. Then, the latter initiates adjustment of the first adjustment section 11A and sends data frame 401, containing the current state of the first adjustment section 11A, to control unit 120B of the second drive unit 12B via gateway 130. Optionally, gateway 130 processes the contents of data frame 401 and generates a new data frame to be transmitted to control unit 120B of the second drive unit 12B. Then, control unit 120B of the second drive unit 12B controls the operation of drive motor 121 of the second drive unit 12B based on the data contained in data frame 401. Finally, control unit 120B of the second drive unit 12B sends data frame 402, containing the current state of the second adjustment section 11B, to control unit 120A of the first drive unit 12A via gateway 130. This (or at least the transmission of data frame 401) occurs periodically, at least until the adjustment is complete.

[0063] The control unit 120B of the second drive unit 12B is configured to interpolate between the control data contained therein during a period of time between two consecutive data frames 401.

[0064] Furthermore, by implementing direction-dependent and / or load-dependent scenarios, intentional position settings can be achieved through position control. In this case, multiple corresponding maneuvers in a specific direction can be considered.

[0065] Electronic synchronization (which offers flexibility through software-based implementation) can influence the position of machinery. This ensures symmetrical wear and extends service life.

[0066] The described communication and control allow the use of a bus system 13 with relatively low bandwidth, thus the position of the first adjustment section 11A and the rotational speed of the first drive unit 12A have relatively low resolution.

[0067] The described longitudinal adjustment device 1 allows for exceptionally high flexibility during conversion and also allows for reduced mechanical stress, thereby further extending service life.

[0068] List of reference numerals

[0069] 1. Longitudinal adjustment equipment

[0070] 10A, 10B first and second tracks

[0071] 11A, 11B First and Second Adjusting Elements

[0072] 12A, 12B First and Second Drive Units

[0073] 120A and 120B control units

[0074] 121 drive motor

[0075] 122 shafts

[0076] 123 worm gear

[0077] 124 spindle nut

[0078] 125 spindle

[0079] 13 bus system

[0080] 130 gateway

[0081] 2 vehicle seats

[0082] 20 Seats

[0083] 21 Backrest

[0084] 3 vehicles

[0085] 30 vehicle floor

[0086] 31 Substructure

[0087] 400-402 data frames

[0088] 500 position controller

[0089] 501 Speed ​​Controller

[0090] 502 Current Intensity Controller

[0091] B Control Command

[0092] DZ speed

[0093] H obstacle

[0094] HW Hardware

[0095] I Current Intensity

[0096] Positions of the first and second adjustment elements of POS_1 and POS_2

[0097] PWM pulse width modulation signal

[0098] SW software

Claims

1. A longitudinal adjustment device (1) for a vehicle seat (2), comprising: - The first adjustment element (11A) is guided on the first track (10A). - The second adjustment element (11B) is guided on the second track (10B). - A first drive unit (12A), by virtue of which the first adjustment element (11A) can be adjusted along the first track (10A), and - A second drive unit (12B) by means of which the second adjustment element (11B) can be adjusted along the second track (10B). Its features are, The control unit (120A) of the first drive device (12A) is communicatively connected to the control unit (120B) of the second drive device (12B).

2. The longitudinal adjustment device (1) according to claim 1, characterized in that, The control unit (120B) of the second drive device (12B) is configured to synchronize the movement of the second regulating element (11B) with the movement of the first regulating element (11A) via the communication connection.

3. The longitudinal adjustment device (1) according to claim 1 or 2, characterized in that, The control unit (120A) of the first drive device (12A) is configured to determine the position of the first adjustment element (11A) along the first track (10A) and transmit the position to the control unit (120B) of the second drive device (12B).

4. The longitudinal adjustment device (1) according to claim 3, characterized in that, The control unit (120B) of the second drive device (12B) is configured to control the drive motor (121) of the second drive device (12B) based on the position transmitted by the control unit (120A) of the first drive device (12A).

5. The longitudinal adjustment device (1) according to claim 4, characterized in that, The control unit (120B) of the second drive device (12B) is configured to calculate the set speed of the drive motor (121) of the second drive device (12B) based on the position transmitted by the control unit (120A) of the first drive device (12A).

6. The longitudinal adjustment device (1) according to claim 4 or 5, characterized in that, The control unit (120B) of the second drive device (12B) is configured to use the position transmitted by the control unit (120A) of the first drive device (12A) as the set position of the second adjustment element (11B) along the second track (10B).

7. The longitudinal adjustment device (1) according to any one of the preceding claims, characterized in that, The control unit (120B) of the second drive device (12B) is configured to calculate the pulse width modulation signal (PWM) based on the calculated set rotational speed.

8. The longitudinal adjustment device (1) according to any one of the preceding claims, characterized in that, The control unit (120A) of the first drive device (12A) is communicatively connected to the control unit (120B) of the second drive device (12B) via a bus system (13).

9. The longitudinal adjustment device (1) according to claim 8, characterized in that, The bus system can be in the form of LIN, CAN, CANFD, FlexRay, Ethernet, K-line, or MOST bus system.

10. The longitudinal adjustment device (1) according to any one of the preceding claims, characterized in that, The control unit (120A) of the first drive device (12A) is communicatively connected to the control unit (120B) of the second drive device (12B) via a gateway (130).

11. The longitudinal adjustment device (1) according to any one of the preceding claims, characterized in that, The control unit (120A) of the first drive device (12A) and the control unit (120B) of the second drive device (12B) are bidirectionally connected.

12. The longitudinal adjustment device (1) according to any one of the preceding claims, characterized in that, The control unit (120A) of the first drive device (12A) is configured to transmit data frames (401) containing control data to the control unit (120B) of the second drive device (12B) at time intervals.

13. The longitudinal adjustment device (1) according to claim 12, characterized in that, The control unit (120B) of the second drive device (12B) is configured to interpolate the control data contained therein during a time period between two consecutive data frames (401).

14. The longitudinal adjustment device (1) according to any one of the preceding claims, characterized in that, The control unit (120B) of the second drive unit (12B) is configured to detect fault conditions and communicate with the control unit (120A) of the first drive unit (12A).

15. A vehicle seat (2) comprising a seat portion (20), a backrest (21), and a longitudinal adjustment device (1) according to any one of the preceding claims, wherein, At least the seat portion (20) is supported on the adjusting elements (11A, 11B) of the longitudinal adjusting device (1).

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