CN112443231B

CN112443231B - Motor vehicle

Info

Publication number: CN112443231B
Application number: CN201910826443.9A
Authority: CN
Inventors: G.休伯; B.法利斯; M.拉赫
Original assignee: Hoerbiger Automotive Komfortsysteme GmbH
Current assignee: Hoerbiger Automotive Komfortsysteme GmbH
Priority date: 2019-09-03
Filing date: 2019-09-03
Publication date: 2022-10-04
Anticipated expiration: 2039-09-03
Also published as: CN112443231A; DE102020121215A1

Abstract

The invention relates to a motor vehicle having a vehicle body (1) which surrounds a passenger compartment (2) and has a base structure (3) with at least one passenger compartment access opening (4) which can be closed by means of a vehicle door (5).

Description

Motor vehicle

Technical Field

The invention relates to a motor vehicle having a body enclosing a passenger compartment, which body has a base structure with at least one passenger compartment access opening which can be closed by means of a vehicle door. The invention relates in particular to a motor vehicle of the type in which the door is mounted on the base structure so as to be pivotable about an axis outward and inward between two end positions and can be opened and closed by means of a drive unit.

Background

In advanced motor vehicles, the comfort of the passengers is very important. In the field of seat comfort, handling comfort and driving comfort which have been discussed for a long time, there is correspondingly a wide range of possible solutions. Conversely, the field of getting on and off comfort has been of increasing interest from relatively recent times.

In the case of sliding doors, drive devices for opening and closing mechanisms of sliding doors are relatively popular, and this (due to the more complex kinematics) does not apply to the same extent to doors that are pivotably supported on the body base structure. Mechanical drive devices have not been widely used. There are, of course, already suggestions, suggestions and solutions, for example electric drives of the Brose company (cf. Claus-Peter)

"autofeshts" in Automobil Industrie,1-2 2018, page 52, f.).

Disclosure of Invention

The object of the invention is to provide a motor vehicle of the type mentioned at the outset, which is distinguished by a high level of driving safety and reliability with regard to the opening and closing of the vehicle door by means of the drive unit and by a high level of comfort for the driver to get on and off, wherein the object is achieved (in particular by a particularly compact and at the same time cost-effective design of the drive unit) in a manner which is also economically and technically expedient even in motor vehicles with high-end products.

The above object is achieved according to the invention by a motor vehicle as specified in claim 1. The motor vehicle therefore comprises a body enclosing a passenger compartment, which body has a base structure with at least one passenger compartment access opening which can be closed by means of a vehicle door, wherein the vehicle door is also mounted on the base structure so as to be pivotable outwardly and inwardly about an axis between two end positions and can be pivoted actively by means of an electrohydraulic drive and holding unit and can be fixed in an open end position and in any intermediate position between the two end positions until a predetermined external force acts. The electrohydraulic drive and holding unit comprises a reversible motor-pump unit, a double-acting hydraulic linear actuator that can be acted upon by the motor-pump unit and is effective between a first connection point on the chassis side and a second connection point on the door side, a line and valve block, a storage tank and a control unit that acts at least on the motor of the motor-pump unit. The hydraulic outputs of the motor/pump units are in each case connected to the connections of the hydraulic linear actuators via main lines, wherein a hydraulically openable throttle check valve is arranged in each main line, the control input of which throttle check valve communicates with the respective other main line, to be precise usually between the hydraulic outputs of the motor/pump units and the throttle check valves. Between the throttle check valve and the connection of the hydraulic linear actuator, a branch line, which ends in a storage tank, branches off from each of the two main lines and has a valve unit which has only one input, one output and one control input and which itself integrally comprises the function of a hydraulically lockable back pressure valve (also referred to as "pre-pressure valve") and a pressure-limiting valve, the limiting pressure of which is higher than the pre-pressure of the back pressure valve. The motor-pump unit, the line and valve block and the storage container are completely mounted in a vehicle door pivotable by means of the associated drive and holding unit, and the hydraulic linear actuator is at least largely mounted in the vehicle door pivotable by means of the associated drive and holding unit.

In the motor vehicle according to the invention, since the electrohydraulic drive and holding unit is characterized by a plurality of characteristics acting in a coordinated manner, various significant advantages can be achieved. In this case, a particularly high degree of intrinsic safety is contributed to by integrating the retaining functionality also in the drive unit, so that the drive unit forms a drive and retaining unit by means of which the vehicle door can be actively pivoted not only between the two end positions, but can even be fixed in the open end position and in any intermediate position between the two end positions. However, the fastening is carried out until a predetermined external force is applied (i.e., "until the external force acting on the vehicle door reaches a predetermined value"), so that the vehicle door can be opened and closed manually, particularly in an emergency. The holding function and the manual emergency operation are not dependent on whether or not current is available. In particular, the hydraulic holding function (in the event of a motor/pump unit shutdown) likewise functions independently of the presence or absence of an electric current at the control unit and/or the motor/pump unit.

In other respects, the electrohydraulic drive and holding unit (with great flexibility in the arrangement of the individual components relative to one another) can be realized in compact dimensions, so that the electrohydraulic drive and holding unit can also be used in doors of typical medium-range motor vehicles, wherein a great potential can also be seen for the relatively low manufacturing costs of such applications.

In the motor vehicle according to the invention, the drive and holding unit for opening, closing and holding the respective door is distinguished by a particularly high degree of integration. The hydraulic drive and holding unit uses a particularly small installation space, wherein the main components (motor-pump unit on the one hand and dual-acting hydraulic linear actuator on the other hand) are furthermore mounted spatially separate from one another and can therefore be arranged individually or uniquely or individually, adapted to the respective conditions. In this way, vehicles in which relatively little installation space and/or only discrete installation space is available for the drive unit in the respective door, because of the medium-class or medium-range vehicle and/or because other devices (for example, space-consuming sound systems) are to be installed in the door, can also be designed according to the invention. In this case, a particularly compact design of the hydraulic drive and holding unit is also facilitated in a very particular manner in that two functions, namely on the one hand the function of a pressure limiting valve, which is intended for preventing destructive excess pressures for the purpose of setting a maximum system pressure in the associated main line to be protected, and on the other hand the function of a hydraulically lockable back pressure valve, which is responsible for the holding function, are integrated in each case (i.e. not only "open" but also "closed" for the subsystem) into a single valve unit having only one input and one output. By means of the two hydraulically lockable back-pressure valves, the respective vehicle door is held in the current position (when the motor-pump unit is shut down), wherein the pre-pressure is selected such that even when the vehicle is parked obliquely, no automatic opening or closing of the vehicle door takes place, whereas an emergency actuation of the vehicle door remains possible in the sense that the vehicle door can be opened and closed manually (against the pre-pressure of the relevant back-pressure valve) when the motor-pump unit is shut down. The manual (emergency actuation) function is largely eliminated by the hydraulic blocking of the respective back pressure valve (when the respective associated main line is pressurized by the motor/pump unit) when the vehicle door is actively adjusted (opened or closed) by the drive unit (on the side of the drive system to which the pressure is applied), and the hydraulic fluid can no longer flow out of the storage tank through the branch line against the pre-pressurization, but against the higher pressure limit of the pressure limiting valve.

In terms of the design of the valve unit provided according to the invention and having a dual function (see above), a particularly preferred development of the invention is characterized in that the valve body is accommodated displaceably in a valve housing of the valve unit, which valve body interacts with a support arranged between the inlet and the outlet, wherein a prestressing spring, which pretensions the valve body in the direction of the valve seat, acts on the valve body, which prestressing spring is supported on a hydraulically adjustable piston, which is accommodated displaceably in the valve housing itself, wherein the maximum prestressing force of the prestressing spring is predetermined by means of a mechanical stop such that the valve body can be lifted off the support. This allows a particularly compact and at the same time reliable design of the valve unit.

A further preferred development of the invention is characterized in that, between the throttle check valve and the connection of the hydraulic linear actuator, a further branch line, which ends in a storage tank, branches off from each of the two main lines and has a filling valve (nachsaugmententil) which opens in the direction of the hydraulic linear actuator. The charging valve is used in the case of (manual) emergency operation of the vehicle door. By providing a separate charge valve for the suction of hydraulic fluid (into the working chamber of the hydraulic linear actuator which increases during an emergency operation), the hydraulic fluid in this application case does not have to be sucked through a (hydraulically openable) throttle check valve arranged in the main line associated with the relevant working chamber. The subsequent flow of hydraulic fluid through the separate charging valve, which is not throttled, is advantageous in terms of safety, since for example a violent opening of the vehicle door therefore remains possible also in an emergency.

According to a further preferred development of the invention, the line and the valve block have a symmetrical hydraulic functionality and comprise two functionally identical subgroups. However, to prevent possible misunderstandings, this does not mean that all set pressure limits or pressure thresholds must be the same in both subgroups of the system. Conversely, an asymmetrical holding functionality may be provided, for example, in that the pre-pressure against which a manual opening of the door is effected in an emergency is set to be smaller than the pre-pressure against which a manual closing of the door is effected in an emergency.

A further preferred development of the invention is characterized in that the hydraulic linear actuator has a displacement sensor which detects the effective distance between the two connection points, wherein the relevant displacement measurement signal is supplied to the control unit. Therefore, the intrinsic safety of the system can be further raised; since in this way, for example, a particularly effective reliability check can be achieved, dangerous operating situations, which may otherwise involve, for example, a risk of trapping limbs, can be avoided if a reliability check is used. This applies in particular when the displacement sensor is designed as a (in particular contactless) absolute displacement sensor, which means in particular that the displacement sensor and/or the evaluation circuit of the displacement sensor are not periodically (for example each time the vehicle door is closed) reset to a reference point on the basis of which a differential displacement measurement is carried out, but rather that the displacement sensor itself (including its evaluation circuit) unambiguously detects the distance between two connection points, depending on the type of construction.

For this purpose, it has proven to be particularly advantageous if the piston rod of the hydraulic linear actuator is helically magnetized, wherein a detection element is arranged on the cylinder of the hydraulic linear actuator, which detection element detects the orientation of the magnetic field. The magnetized helix of the piston rod has a pitch here such that the helix angle remains below 360 ° over the entire adjustment distance of the piston rod. It is thus ensured that all signals provided by the detection element (which detects the orientation of the magnetic field) can be unambiguously assigned to exactly one specific position of the piston rod (relative to the cylinder).

In a very particularly preferred embodiment, the pulses of the displacement sensor are converted in the control unit into an activation of the electrohydraulic drive and holding unit in the relevant direction of movement. Thus, a mechanical pivoting of the vehicle door can be initiated by a "pushing" and/or a "collision" of the vehicle door in the relevant direction in order to open or close the vehicle door. The same situation is extremely advantageous in particular when the door is closed from the outside; since in this case the person concerned usually has no free hands to operate the switches etc., and can nevertheless initiate the closing of the door by hitting the door.

A further very advantageous embodiment is characterized in that the control unit has a memory for a user-definable and/or user-definable switching value, which corresponds to a certain opening degree of the vehicle door, which, upon reaching this switching value, can be activated only in the sense of closing the vehicle door. In this way, it is effectively prevented that the door (accidentally) is opened beyond a certain opening angle by means of the electrohydraulic drive unit, so that damage to the door and/or to objects located in the vicinity of the motor vehicle outside the motor vehicle can be avoided, in particular when the motor vehicle is parked in a narrow environment.

According to a further advantageous development of the invention, the motor vehicle has a door lock sensor, wherein a certain deviation of the signal of the door lock sensor from the displacement measurement signal provided by the displacement sensor triggers an alarm. A higher safety for the passengers of the vehicle can thus be achieved.

Drawings

The invention will be further elucidated on the basis of a preferred embodiment shown in the drawing. In this case, the amount of the solvent to be used,

figure 1 shows schematically a motor vehicle according to the invention in the context of basic components,

FIG. 2 shows, by means of a hydraulic connection diagram, a hydraulic drive and holding unit for opening and closing of a door and for the stationary use thereof in a motor vehicle according to FIG. 1, and

fig. 3 shows in detail the valve unit used in the hydraulic drive and holding unit according to fig. 2.

Detailed Description

The motor vehicle schematically illustrated in fig. 1 in a sectional view of interest here has a body 1 in the usual manner. The vehicle body encloses a passenger compartment 2 and has a basic structure 3 with two front and two rear passenger compartment entrances 4. Each of which is closable by means of a vehicle door 5. For this purpose, the vehicle door 5 is mounted on the base structure 3 of the vehicle body 1 so as to be pivotable about an axis X (which is substantially vertical here) between two end positions laterally outwardly and inwardly. Insofar as described above, the motor vehicle shown corresponds to the well-known prior art, so that no further elaboration is necessary.

In order to open or close the vehicle door and to fix it in the (possibly partially) open position, the vehicle door 5 is actively pivotable and fixable in the open end position and in any intermediate position between the two end positions by means of a corresponding electrohydraulic drive and holding unit 6, respectively. The electrohydraulic drive and holding unit 6 in this case comprises a motor-pump unit 7, a hydraulic linear actuator 8, a line and valve block 9, a storage tank 10 and a control unit 12 acting on a motor 11 of the motor-pump unit 7. The motor-pump unit 7, the line and valve block 9 and the storage container 10 are installed completely in the vehicle door 5 to be adjusted, whereas the hydraulic linear actuator 8 is installed only approximately completely in the vehicle door 5 to be adjusted, since the piston rod 13 of the linear actuator 8 projects beyond the vehicle door 5 even in its position of maximum retraction into the cylinder 14.

The hydraulic linear actuator 8 acts between a first connection point 15 on the base structure side and a second connection point 16 on the door side. The hydraulic linear actuator is designed to be dual-acting, so that the first load acts in the sense of a reduction in the overall length (retraction of the piston rod 13 into the cylinder 14) and the second load acts in the sense of an increase in the overall length (extension of the piston rod 13 out of the cylinder 14). The motor-pump unit 7 is designed to be switchable for a correspondingly switchable application of the hydraulic linear actuator 8. As schematically shown in fig. 1, the motor-pump unit 7, the reservoir 10 and the valve block 17 can form a hydraulic aggregate 18 in terms of construction, the linear actuator 8 being connected to the hydraulic aggregate 18 by two (optionally flexible) lines 19.

The hydraulic connection according to fig. 2 shows the entire hydraulic system in detail. It can be seen that the piping and valve block 9, which comprises all the components in contact with the hydraulic liquid except the motor-pump unit 7, the linear actuator 8 and the storage container 10, has a symmetrical hydraulic functionality. The line and valve block 9 comprises two functionally identical subgroups A, B with respective

main lines

23A, 23B with hydraulically openable throttle check valves 22 connecting the

hydraulic outputs

20A, 20B of the motor-pump unit 7 with the

connections

21A, 21B of the hydraulic linear actuator 8, and a common reversing valve device 24; the reversing valve arrangement connects the two

main lines

23A, 23B to each other between the respective

hydraulic outputs

20A, 20B of the motor-pump unit 7 and the respective throttling check valve 22 and communicates with the storage tank 10. The control input 26 of the hydraulically openable throttle check valve 22 communicates via a control line 25 with the respective other

main line

23B, 23A between the respective

hydraulic output

20B, 20A of the motor-pump unit 7 and the throttle check valve 22 associated therewith.

Between the throttle flap valve 22 and the connection ends 21A, 21B of the hydraulic linear actuator 8, a first branch line 27, which ends in the storage tank 10, branches off from each of the two

main lines

23A, 23B. A valve unit 28 is integrated in this first branch line. The valve unit 28 (between its input 29 and its output 30) has a dual functionality in that it fulfills the function of a hydraulically lockable back pressure valve 31 on the one hand and a pressure limiting valve 32 on the other hand. The extreme pressure limit of the pressure limiting valve 32 is higher than the pre-pressure predetermined by the backpressure valve 31, which determines the degree of the predetermined external force effect acting on the vehicle door 5, with which the vehicle door 5 (with the motor/pump unit 7 deactivated) can be opened or closed manually. The control input 33 of the hydraulically lockable backpressure valve 31 communicates via the control line S with the associated

main line

23A, 23B between the respective

hydraulic output

20B, 20A of the motor-pump unit 7 and the throttle check valve 22 associated with this hydraulic output; therefore, in the case where the relevant

main lines

23A, 23B are pressurized by the motor-pump unit 7, the backpressure valve 31 is blocked. As a result, in the case of operation of the pump 34, the hydraulic fluid is discharged from the associated

main line

23A, 23B via the associated first branch line 27 into the storage tank 10 only if the limit pressure of the pressure-limiting valve 32 is exceeded.

Between the throttle flap valve 22 and the connection ends 21A, 21B of the hydraulic linear actuator 8, a further second branch line 35 branches off from each of the two

main lines

23A, 23B, which likewise ends in the storage tank 10. Charging valves 36 that open in the direction of the hydraulic linear actuator 8 are integrated in the second branch lines 35. In the case of a manual adjustment of the vehicle door 5 when the motor-pump unit 7 is deactivated, hydraulic fluid is pumped via the charge valve into the working chamber of the linear actuator 8, in which the volume thereof increases.

The hydraulic linear actuator 8 has a displacement sensor 37 which detects the effective distance between the two connection points 15, 16. The displacement sensor 37 is designed as a contactless absolute displacement sensor 38. For this purpose, the piston rod 13 of the hydraulic linear actuator 8 is magnetized helically over the entire adjustment distance of the piston rod with a helix angle of slightly less than 360 °; and a detection element 39 for detecting the orientation of the magnetic field generated by the magnetization of the piston rod 13 is arranged on the cylinder 14 of the hydraulic linear actuator 8. The displacement measurement signal provided by the displacement sensor 37 is fed to the control unit 12.

The control unit 12 is even able to detect a minimal change in the effective length of the linear actuator 8 depending on the direction of the length change. This enables the use of pulses of the displacement sensor 37 in the control unit 12, so as to initiate the activation ("push-to-open", "push-to-close") of the electrohydraulic drive and holding unit 6 in the relevant direction of movement. Fig. 2 also shows a control panel P, which is arranged in the passenger compartment 2 and which communicates with the control unit 12 and has buttons T to be manually actuated.

Fig. 3 shows a preferred design of the valve unit 28 with dual functionality. For this purpose, a valve body 42, which interacts with a valve seat (sealing seat) 43 arranged fluidically between the inlet 29 and the outlet 30, is accommodated displaceably in a corresponding bore 41 in a valve housing 40 (formed by the valve block 17) of the valve unit 28. A pretension spring 44, which pretensions the valve body 42 in the direction of the valve seat 43, acts on the valve body 42. In a corresponding pressure ratio (in the case of a lifting of the valve body 42 from the valve seat 43), a flow through the non-return valve 45 formed in this way can be achieved in the direction from the inlet 29 to the outlet 30.

The pretension spring 44 is supported on a piston 47 which is in turn displaceably received in the valve housing 40 (in a bore 46 accommodating the piston). The adjustment distance of the piston 47 is limited by two stops, namely a first stop 49 formed on the closing plug 48 and a second stop 51 formed by a shoulder 50 of the bore 46 receiving the piston 47. The closing plug 48 (sealed off from the valve housing 40 by means of the sealing ring 52) is axially adjustable by means of a screw arrangement 53, as a result of which a minimum prestress of the prestressing spring 44 can be established.

The piston 47 is hydraulically adjustable. For this purpose, the piston is sealed in the bore 46 by means of an annular seal 54. A control chamber 55 is thus defined which is delimited by the surfaces of the valve housing 40 which close the plug 48 and the piston 47, and a control input 56 opens into the control chamber 55. Due to the difference in area between the end face 57 of the piston 47 and the opposing annular face 58 (when the passage 59 is considered in each case), the piston 47 is moved by the pressure loading of the control chamber 55 from a first end position of the piston, which is defined by the first stop 49, into a second end position of the piston, which is defined by the second stop 51. The prestress of the prestressing spring 44 is thereby increased, wherein, however, the maximum prestress of the prestressing spring 44 (defined by the second stop 51) is predetermined such that the valve body 42 can still be lifted from the valve seat 43 at a correspondingly high pressure on the inlet side of the check valve 45. As a result, the valve unit 28 is therefore preset with no control pressure application with a higher limit pressure, which is reached at the input 29, and therefore a flow through from the input 29 to the output 30.

Claims

1. Motor vehicle with a body (1) enclosing a passenger compartment (2), said body having a base structure (3) with at least one passenger compartment access opening (4) which can be closed by means of a vehicle door (5), characterized in that,

the door (5) is mounted on the base structure (3) so as to be pivotable about an axis (X) between two end positions;

the vehicle door (5) can be pivoted actively by means of an electrohydraulic drive and holding unit (6) and can be fixed in an open end position and in any intermediate position between the two end positions until a predetermined external force acts, wherein the electrohydraulic drive and holding unit (6) comprises a reversible motor-pump unit (7), a double-acting hydraulic linear actuator (8) which can be acted upon by the motor-pump unit and which is effective between a first connection point (15) on the chassis side and a second connection point (16) on the vehicle door side, a line and valve block (9), a storage container (10) and a control unit (12) which acts at least on the motor (11) of the motor-pump unit (7);

the motor-pump unit (7), the line and valve block (9) and the storage container (10) are completely mounted in a vehicle door (5) pivotable by means of the associated drive and holding unit (6), and the hydraulic linear actuator (8) is at least largely mounted in the vehicle door (5) pivotable by means of the associated drive and holding unit (6);

the line and valve block (9) comprises two main lines (23A, 23B) which respectively connect the hydraulic outputs (20A, 20B) of the motor-pump unit (7) to the connections (21A, 21B) of the hydraulic linear actuator (8), wherein a hydraulically openable throttle check valve (22) is arranged in each main line (23A, 23B), the control input (26) of which communicates with the respective other main line (23B, 23A);

between the throttle check valve (22) and the connection (21A, 21B) of the hydraulic linear actuator (8), a branch line (27) which ends in the reservoir (10) branches off from each of the two main lines (23A, 23B) and which has a valve unit (28), which valve unit (28) has only one input (29), one output (30) and one control input (33) and which itself integrally comprises the function of a hydraulically lockable back pressure valve (31) and the function of a pressure limiting valve (32), the limiting pressure of which pressure limiting valve (32) is higher than the pre-pressure of the back pressure valve (31), wherein a valve body (42) is accommodated movably in a valve housing (40) of the valve unit (28), the valve body (42) interacting with a valve seat (43) which is arranged fluidically between the input (29) and the output (30), wherein a pre-stressing spring (44) which pre-stresses the valve body (42) in the direction of the valve seat (43) acts movably on the valve body (42), wherein the pre-stressing spring (44) acts on the valve body (44) itself by means of a mechanical pre-stressing spring (47), wherein the pre-stressing of the valve body (44) is arranged in the direction of the valve housing (40), wherein the valve body (44) is arranged movably supported by means of the pre-stressing spring (47), wherein a maximum pre-stressing force of the pre-stressing spring (47) is adjustable pre-stressing of the valve body (44), the valve body (51), wherein the hydraulic piston (44), wherein the pre-stressing spring (47) is arranged in the valve housing, wherein the valve body (44), the pre-stressing spring (44) is arranged in the hydraulic linear actuator, wherein the hydraulic linear actuator, the hydraulic piston (40), so that the valve body (42) can be lifted from the valve seat (43).

2. A motor vehicle according to claim 1, characterized in that between the throttle check valve (22) and the connection (21A, 21B) of the hydraulic linear actuator (8) a further branch line (35) which ends in the storage tank branches off from each of the two main lines (23A, 23B) and has a filling valve (36) which opens in the direction of the hydraulic linear actuator (8).

3. Motor vehicle according to claim 1 or 2, characterized in that the line and valve block (9) has a symmetrical hydraulic functionality and comprises two functionally identical subgroups (A, B).

4. A motor vehicle according to claim 1, characterized in that the hydraulic linear actuator (8) has a displacement sensor (37), the displacement sensor (37) detecting the effective distance between the two connection points (15, 16), wherein the relevant displacement measurement signal is supplied to the control unit (12).

5. The motor vehicle according to claim 4, characterized in that the control unit (12) has a memory for a user-presettable and/or user-presettable switching value corresponding to a certain opening degree of the vehicle door (5) by means of an environmental sensor, from which switching value the electrohydraulic drive and holding unit (6) can only be activated for closing the vehicle door (5).

6. A motor vehicle according to claim 4 or 5, characterized in that the pulses of the displacement sensor (37) are converted in the control unit (12) into an activation of the electrohydraulic drive and holding unit (6) in the relevant direction of movement.

7. A motor vehicle according to claim 4 or 5, characterized in that the displacement sensor (37) is designed as a contactless absolute displacement sensor (38).

8. A motor vehicle according to claim 7, characterized in that the piston rod (13) of the hydraulic linear actuator (8) is helically magnetized, wherein a detection element (39) for detecting the orientation of the magnetic field is arranged on the cylinder (14) of the hydraulic linear actuator (8).

9. A motor vehicle as claimed in claim 4 or 5, characterized in that the vehicle has a door lock sensor, wherein a certain deviation of the signal of the door lock sensor from the displacement measurement signal triggers an alarm.