GB2546776A

GB2546776A - An inductive power transfer pad, system for inductive transfer and method of operating an inductive power transfer pad

Info

Publication number: GB2546776A
Application number: GB1601598.4A
Authority: GB
Inventors: Wechsler Simon; Gunt Roman
Original assignee: Bombardier Primove GmbH
Current assignee: Bombardier Primove GmbH
Priority date: 2016-01-28
Filing date: 2016-01-28
Publication date: 2017-08-02
Also published as: GB201601598D0; WO2017129653A1

Abstract

The power transfer pad 1 of a system for inductive power transfer to a vehicle comprises a stationary part 2 and a movable part 3, wherein the stationary part 2 has a bottom surface 4 and wherein the movable part 3 has an upper surface 7. The movable part 3 is movable between a retracted state and an extended state. When in the retracted state at least a portion of the upper surface 7 is inclined with respect to the bottom surface 4 of the stationary part 2. The arrangement is said to allow standing water to run off the power transfer pad 1 such that water and/or ice does not interfere with the power transfer.

Description

An inductive power transfer pad, system for inductive transfer and method of operating an inductive power transfer pad

The invention relates to an inductive power transfer pad and a system for inductive power transfer, in particular to a vehicle. Furthermore, the invention relates to a method of operating an inductive power transfer pad.

Electric vehicles, in particular a track-bound vehicle, and/or a road automobile, can be operated by electric energy which is transferred by means of an inductive power transfer. Such a vehicle may comprise a circuit arrangement which can be a traction system or a part of a traction system of the vehicle, comprising a receiving device adapted to receive an alternating electromagnetic field and to produce an alternating electric current by electromagnetic induction. Furthermore, such a vehicle can comprise a rectifier adapted to convert an alternating current (AC) to a directing current (DC). The DC can be used to charge a traction battery or to operate an electric machine. In the latter case, the DC can be converted into an AC by means of an inverter. The inductive power transfer is usually performed using two sets of e.g. three-phase winding structures. A so-called primary winding structure is installed on the ground and can be fed by a wayside power converter (WPC). The primary winding structure can be part of a primary unit. A secondary winding structure is installed on the vehicle. For example, the secondary winding structure can be attached underneath the vehicle, in the case of trams under some of its wagons. For an automobile, it can be attached to the vehicle chassis. The secondary winding structure is usually part of a so-called pick-up-arrangement or receiving device or secondary unit. The primary winding structure and the secondary winding structure form a high frequency transformer to transfer electric energy to the vehicle. This can be done in a static state (when there is no movement of the vehicle) and in a dynamic state (when the vehicle moves).

In particular in the case of road automobiles, a stationary primary unit can comprise a plurality of elements which are often arranged spatially separated. GB 2512864 A1 discloses an inductive power transfer pad, in particular an inductive power transfer pad of a system for inductive power transfer to a vehicle. The power transfer pad comprises a housing, a primary winding structure and a connecting terminal, wherein the inductive power transfer pad further comprises an inverter, wherein the inverter is arranged within the housing, wherein an input side of the inverter is electrically coupled to the connecting terminal and an output side of the inverter is electrically coupled to the primary winding structure. WO 2015/128450 A1 discloses an inductive power transfer pad, in particular a power transfer pad of a system for inductive power transfer to a vehicle, comprising a stationary part and a movable part. The movable part comprises a primary winding structure, wherein the movable part is movable between a retracted state and an extended state. The power transfer pad is designed and/or controllable such that the movable part is only movable to a position from a set of predetermined positions, wherein the set of predetermined positions is a subset of the set of all positions between the retracted and the extended state.

During operation of such a power transfer pad, tail water can rest on an upper surface of the power transfer pad. Such tail water can negatively affect an operability of the transfer pad, in particular since the risk of water ingress into the charging pad, e.g. at screwing points, is increased. Further, freezing water can provide an undesired, additional load for the charging pad. Further, there is the risk that metal objects are contained in frozen water on the upper surface. Such metal objects can negatively affect the charging process.

There is the technical problem of improving the efficiency of inductive power transfer of an inductive power transfer pad which comprises a movable and a stationary part.

The solution to said technical is provided by the subject-matter with the features of claims 1,10 and 11. Further advantageous embodiments of the invention are provided by the subject-matter of the subclaims.

It is a basic idea of the invention to provide an inclined upper surface of the movable part such that water drains in a retracted state of the movable part.

An inductive power transfer pad is proposed, in particular a power transfer pad of a system for inductive power transfer to a vehicle. The inductive power transfer pad (IPT pad) can be part of a primary unit of a system for inductive power transfer. The IPT pad comprises a stationary part to be installed on a surface of the ground, e.g. a surface of a route or a parking lot, or within the ground. Further, the IPT pad comprises a movable part. The movable part can comprise a primary winding structure of the system for inductive power transfer. If energized, the primary winding structure generates an alternating electromagnetic field. This alternating electromagnetic field can be received by a secondary winding structure which can e.g. be installed on a vehicle.

Further, the movable part is movable between a retracted state and an extended state. The IPT pad can comprise at least one actuating means, wherein the movable part is movable by the at least one actuating means. In the context of this invention, the term "actuating means" can denote an entity of all components or elements by which the motion of the movable part is generated. The term "actuating means" can thus denote at least one actuator and/or at least one motion guiding means which can also be referred to as lifting mechanism or lifting kinematics. Further, the term "actuating means" can also denote coupling means for mechanically coupling the actuator and the movable part.

The movable part can be movable in a translational motion into or against a first direction. The first direction can be a direction which is oriented from the primary winding structure to a secondary winding structure which is arranged in order to receive the alternating electromagnetic field. Thus, the first direction can be a direction of energy transfer if energy is transferred from the primary side to the secondary side. If the IPT pad is installed on the ground, the first direction can be parallel to a vertical direction, wherein the vertical direction is oriented from bottom to top if it is oriented against the direction of a gravitational force.

Alternatively, the movable part can be movable along a curved trajectory, wherein at least one section of the curved trajectory extends at least partially in the first direction. Further, the said section of the curved trajectory can also extend at least partially along a direction perpendicular to the first direction. This means that a direction vector of at least one section of the curved trajectory can comprises a portion oriented in the first direction and a portion oriented in a direction perpendicular to the first direction. The movement along the curved trajectory can be guided by at least one guiding means, e.g. a curve guided motion link.

It is further possible that the vertical direction is oriented perpendicular to a plane comprising the primary winding structure. In this case, the primary winding structure can be substantially designed as a planar winding structure. It is further possible that the vertical direction is oriented orthogonal to a bottom surface of the stationary part which will be explained later.

In the context of this invention, directional terms such as "upper", "lower", "above", "under", "lowest", "highest", "bottom" refer to the vertical direction. In the retracted state, the movable part, in particular an upper surface of the movable part, can be positioned at a retracted position, in particular with respect to the first direction. In the retracted state, the upper surface can be arranged at a lowest vertical position of the working space of the movable part. In the retracted state, a maximal height of the power transfer pad, i.e. a distance of the highest portion of the power transfer pad from the bottom surface along the vertical direction can be minimal. Correspondingly, the movable part can be positioned at an extended position in the extended state. In the extended state, the movable part, in particular the upper surface, can be arranged at a predetermined highest vertical position of the working space of the movable part. In the extended state, the height of the power transfer pad can be maximal.

The bottom surface can be used to mount the IPT pad to a mounting structure, in particular to a surface of the route. Retracted state and extended state can be defined by mechanical elements, e.g. stop elements, and/or by the design of the actuating means.

The height in the retracted state can be chosen from an interval from 50 mm to 110 mm, in particular from an interval from 60 mm to 90 mm. The height in the extended state can e.g. be chosen from an interval of 65 mm to 230 mm.

As mentioned before, the stationary part has a bottom surface. The movable part has an upper surface. The upper surface can e.g. be an upper surface of a housing comprising elements of the movable part, in particular the primary winding structure. In this case, it is possible that the housing is moved from the retraced state to the extended state and vice versa.

According to the invention, at least a portion of the upper surface is inclined with respect to the bottom surface in the retracted state of the movable part. Preferably, the complete upper surface is inclined with respect to the bottom surface in the retracted state. This can mean that there is a non-zero angle enclosed by the upper surface and the bottom surface.

The upper surface and/or the bottom surface can be plain surface(s). In other words, the upper surface can be slanted or sloped or tilted with respect to the bottom surface.

In the retracted state, the vertical direction and the upper surface can enclose an angle which is unequal to 90°. Preferably, the angle is chosen from an interval of 80° (inclusive) to 90“(exclusive) or an interval of 90°(exclusive) to 100°(inclusive). Preferably the angle is 89° or 91 °. This advantageously allows water to drain from the upper surface in the retracted state without requiring an additional height for the charging pad. As such water, in particular tail water, does not rest on the upper surface, the efficiency of the inductive power transfer is not negatively affected by such water.

In another embodiment, the at least one portion of the upper surface is oriented parallel to the bottom surface in the extended state of the movable part. In particular, the upper surface can be oriented parallel to the bottom surface. This means that the upper surface is oriented orthogonal to the vertical direction in the extended state.

The advantageously further increases the efficiency of the inductive power transfer as a desired alignment between a secondary winding structure (which is usually also oriented perpendicular to the vertical direction) relative to the primary winding structure is provided in the extended state. In particular, the primary and the secondary winding structure can be oriented substantially parallel to each other in the desired aligned state. Further, the distance between the primary winding structure and the secondary winding structure is minimized in the extended state. Thus, the extended state is usually the state in which the primary winding structure is operated.

In another embodiment, the bottom part provides a first contact section for a first border section of the movable part and a second contact section for a second border section of the movable part, wherein one of the contact sections is arranged lower than the remaining contact section. The first border section can e.g. be a rear end border section and the second border section can e.g. be a front end border section. Preferably, the first contact section is arranged lower than the remaining contact section. The contact section denotes a section of the stationary part, in particular of a housing which is in mechanical contact with the movable part in the retracted state. As one of the contact sections is arranged at a lower vertical position than the other contact section, the upper surface is slanted.

This advantageously provides an easy mechanical design for ensuring the inclination of the upper surface.

In another embodiment, the second contact section is stepped. This means that the primary unit can have a stepped or staggered section, wherein one or multiple of the steps can provide the contact section.

In another embodiment, the power transfer pad comprises at least one motion guiding means. The at least one motion guiding means can also be referred to as guiding mechanism or lifting mechanism. The motion guiding means is designed and/or arranged such that the movable part executes a tilting motion when moved from the retracted state to the extended state or vice versa. Alternatively or in addition, the movable part can be moved by the activating means such that the tilting motion is executed.

The tilting motion can e.g. be a rotational motion around an axis which is oriented perpendicular to the vertical direction. In particular, the rotational axis can be parallel to a lateral axis of the stationary part. A longitudinal axis of the stationary part and a lateral axis can span a plane which is oriented parallel to the bottom surface of the stationary part. The longitudinal axis can be a central axis of the stationary part. A longitudinal direction can correspond to a desired motion of the secondary winding structure when being arranged above the primary winding structure e.g. a driving direction of the vehicle. The longitudinal direction, the lateral direction and the vertical direction can be oriented orthogonal to each other.

The tilting motion advantageously allows eliminating the inclination during the movement from the retracted state to the extended state.

In another embodiment, the movable part executes the tilting motion at the beginning of the movement from the retracted state to the extended state. In particular, the movable part executes the tilting motion before executing a motion away from the stationary part. The motion away from the stationary part can e.g. be a translational motion or a movement along a curved trajectory away from the stationary part. This has been explained before.

The at least one motion guiding means can be designed correspondingly. This means that the motion from the retracted to the extended state can comprise a rotational motion i.e. the tilting motion, and a following motion, in particular a translational motion along the vertical direction. The tilting motion is executed before the following motion during the movement from the retracted state to the extended state. If moved from the extended state to the retracted state, the tilting motion can be executed at the end of the movement form the extended state to the retracted state, e.g. after the translational motion. This, in turn, effects that the inclination is eliminated before the lifting or upwards motion of the movable part. This advantageously provides a desired orientational alignment in each vertical position of the movable part during the movement from the retracted to the extended state.

It is, of course, also possible that the tilting motion is executed at least partially simultaneously to or after a motion away from the stationary part if the movable part is moved from the retracted state to the extended state.

In another embodiment, the power transfer pad comprises a primary winding structure, wherein the primary winding structure, in particular a planar primary winding structure, is arranged parallel to the upper surface. The primary winding structure can e.g. comprise sections extending along a longitudinal axis of the primary winding structure and sections extending along a lateral axis of the primary winding structure, wherein a plane spanned by the longitudinal axis and the lateral axis is oriented parallel to the upper surface. It is further possible that the primary winding structure comprises or provides at least one loop structure. The loop structure can e.g. provided by a coil. The loop structure can have a desired geometric shape, e.g. a rectangular or a circular shape. In this case, a central axis of symmetry of the loop structure can be oriented orthogonal to the upper surface.

This advantageously ensures the reduction of the orientational misalignment in the extended state.

In a preferred embodiment, the power transfer pad comprises at least one carrier plate for at least one foreign object detection means, wherein the at least one carrier plate is arranged parallel to the upper surface. The carrier plate can e.g. be a printed circuit board.

Independent of this embodiment, the IPT pad can comprise an object detection means. The object detection means can denote a system for detecting a foreign object, in particular a metal object, within a charging volume of the power transfer pad. Alternatively or in addition, the object detection means can denote a system for detecting a moving object within the charging volume. The charging volume can denote a volume through which at least a predetermined portion, e.g. 80 %, 90 % or 95 % of the electromagnetic field generated by the primary winding structure extends. The charging volume can also denote the volume to which the total electromagnetic field generated by the primary winding structure extends. Also, the charging volume can denote the volume above the power transfer pad, e.g. above the primary winding structure. A charging surface can denote a bottom surface of the charging volume. In particular, the charging surface can be part of the upper surface of the movable part.

The at least one object detection means can comprise at least one inductive sensing system, wherein an active or a passive detection can be performed by the inductive sensing system. In each case, the inductive sensing system can comprise one or multiple detection winding(s). Multiple detection windings can be arranged in an array structure wherein the array structure covers the charging surface of the power transfer pad at least partially. In the case of an active detection, one or more excitation winding(s), which can also be referred to as exciter windings can be used. An active object detection can be performed by monitoring properties of an excitation field generated by the excitation winding(s) and received by the detection winding(s). In the case of a passive detection, only one or more passive winding(s) is/are used. A passive object detection can be performed by monitoring properties of the passive winding(s), in particular an inductance. Such an inductive detection system is disclosed in GB 2508923 A or in GB 2517679 A. In the context of this invention, a detection system can be designed according to one of the embodiments as claimed in GB 2508923 A or in GB 2517679 A which are incorporated by reference. Further, an object detection system can be designed as disclosed in DE 10 2014 207 427.4 which is also incorporated by reference.

Alternatively, the at least one object detection means can also comprise at least one capacitive sensing system. Such a capacitive detection system is disclosed in GB 2508924 A1. In the context of this invention, a detection system can be designed according to one of the embodiments as claimed in GB 2508924 A1 which is incorporated by reference.

The object detection means can also be an image-based object detection means, wherein such an image-based detection means can e.g. comprise an imaging capturing device e.g. a camera.

Arranging the at least one carrier plate parallel to the upper surface advantageously improves an object detection within the charging volume which extends perpendicular to the upper surface.

In another embodiment, the object detection means comprises at least one winding structure. As mentioned before, the at least one winding structure can be a detecting winding structure. Further, the object detection means can also comprise an exciting winding structure. It is possible that excitation winding encloses an inner volume or inner area. Within this inner volume or inner area, at least one, preferably multiple, detection winding structures can be arranged. The at least one winding structure can have a rectangular shape.

Further proposed is an inductive power transfer system, in particular for an inductive energy transfer to a vehicle. The inductive power transfer system comprises an inductive power transfer pad according to one of the embodiments described in this invention. Further, the inductive power transfer system comprises at least one receiving device for receiving an alternating electromagnetic field generated by a primary winding structure of the inductive power transfer pad.

Further proposed is a method of operating an inductive power transfer pad. The inductive power transfer pad is designed according to one of the embodiments described in this invention.

According to the invention, at least a portion of the upper surface is inclined with respect to the bottom surface in the retracted state of the movable part. This can mean that if the movable part is moved or arranged in the retracted state, its upper surface is inclined or moved to an inclined state.

Further, the primary winding structure can be energized if the movable part is not in the retracted state. In particular, the primary winding structure can only be energized if the movable part is not in the retracted state. More particular, the primary winding structure can be energized if the movable part is in the extended state.

The method can be performed with an inductive power transfer pad according to one of the embodiments described in this invention.

In another embodiment, the movable part executes a tilting motion when moved from the retracted state to the extended state. This has been explained before.

In another embodiment, the movable part executes the tilting motion before executing a translational motion when moved from the retracted state to the extended state.

It is, of course, also possible that the tilting motion is at least partially executed simultaneous to the translational motion or that the tilting motion is executed after the translational motion has been finished.

It is furthermore possible that the movable part is only moved to a position from a set of predetermined positions, wherein the set of predetermined positions is a subset of the set of all positions between the retracted state and the extended state. In particular, the movable part is only moved to the retracted state or to the extended state. Further, the movable part can be moved in steps.

It is further possible that the movable part is movable to a position from the set of predetermined positions such that at least a minimal air gap height is provided, wherein the minimal air gap height is larger than zero. The air gap denotes an air gap between the power transfer pad and a vehicle. The minimal air gap height can be equal to the distance between the ground clearance of a vehicle and the movable part, e.g. the upper surface of the movable part. A ground clearance, which can also be referred to as ride height, can be defined as the shortest distance between a flat-level surface in any part of the vehicle other than those parts designed to contact the ground (such as tires, tracks, etc.). The ground clearance can e.g. be provided in an unloaded configuration, e.g. with no cargo and no passengers. The power transfer pad can comprise means for determining the air gap or a ground clearance of a vehicle approaching the power transfer pad and/or arranged above the power transfer pad.

Further, the power transfer pad, in particular the stationary part, can comprise a converter and at least one DC connecting terminal for connecting the power transfer pad to an external DC voltage supply means. An input side of the converter can be electrically coupled to the DC connecting terminal and an output side of the converter is electrically coupled to the primary winding structure. Alternatively or in addition, the power transfer pad, in particular the stationary part, comprises at least one AC connecting terminal for connecting the stationary part to an external voltage supply means, wherein the converter is coupled to the AC connecting terminal via a rectifier.

Further, the power transfer pad can comprise at least one DC voltage supply unit, wherein the DC voltage supply unit is connected to a DC connecting terminal of the stationary part. Further, the power transfer pad can comprise at least one communication means for communicating with a vehicle.

Further, the power transfer pad can comprise a scissor lift, an air actuator or a jack-like lift or a sliding block guide as motion guiding means.

The invention will be explained with reference to the attached figures. The figures show:

Fig. 1 a schematic cross section through an inductive power transfer pad in a retracted state,

Fig. 2 a schematic side view of an inductive power transfer pad in an extended state.

In the following, the same reference numerals will denote elements with the same or similar technical features.

Fig. 1 shows a schematic cross section of an IPT pad 1. The IPT pad 1 comprises a stationary part 2 and a movable part 3. The stationary part 2 has a bottom surface 4 for installing the IPT pad 1 on a ground 5 (see Fig. 2). The bottom surface 4 of the stationary part can be also the bottom surface of a housing 8 of the stationary part. Further shown is that the movable part 3 has a housing 6 with an upper surface 7.

Fig. 1 shows that the upper surface 7 is inclined with respect to the bottom surface 4 in the retracted state of the movable part 3. An angle between the inclined upper surface 7 and the bottom surface 4 can be in the range of 0,5° to 5°, preferably 1 °.

Further shown is a vertical direction z and a longitudinal direction x. A lateral direction y (not shown in Fig. 1) is oriented perpendicular to the drawing sheet and oriented away from an observer. The bottom surface 4 is oriented orthogonal to the vertical direction z. The vertical direction z intersects the upper surface 7 with an angle in the range of 89,5° to 85°, preferably of 89°.

Within the housing 6 of the movable part 3, a primary winding structure (not shown) can be arranged. The primary winding structure can be arranged under a printed circuit board 9. The printed circuit board 9 is oriented parallel to the upper surface 7, in particular an upper surface of the printed circuit board 9. At least one detecting winding structure can be arranged on or within the printed circuit board 9. Further, if applicable, at least one exciting winding structure can be arranged on or within the printed circuit board 9. The detecting winding structure and, if applicable, the exciting winding structure can be part of an inductive object detection system. The primary winding structure, which is not shown, can e.g. be a planar primary winding structure which can also be substantially arranged parallel to the upper surface 7.

Further shown is that the stationary part 8 provides a first contact section 10a for the rear end border section of the movable part 3. Further, the stationary part provides a second contact section 10b for the front end border section of the movable part 3, in particular of the housing 6. With respect to the vertical direction z, the first contact section 10a is arranged lower than the second contact section 10b.

In the cross section shown in Fig. 1, it can be seen that the second contact section 10b is stepped. Further shown is that the front end border section of the movable part 3, in particular the housing 6, is also stepped. Contact areas of the stepped section of the housing 6 contact corresponding contact sections of the stepped second contact section 10b abut.

In summary, the contact sections 10a, 10b of the stationary part 2 are arranged such that if the movable part 3 contacts the stationary part 2 in the retracted state, the upper surface 7 is inclined.

Fig. 2 shows a schematic side view of an inductive power transfer pad 1 in an extended state. Further shown is a receiving device 11 of a vehicle 12. The receiving device 11 has a secondary winding structure (not shown) which can also be designed as a substantially planar winding structure. The bottom surface 4 of the stationary part 2 is installed on the ground 5. During the movement from the retracted state into the extended state, the movable part 3 first executes a tilting motion which is indicated by an arrow 13. The tilting motion is a rotational motion around a rotational axis which is oriented parallel to the lateral axis. Second, the movable part 3 executes a translational motion which is indicated by another arrow 14. The translational motion 14 is executed after the tilting motion 13. After having finished the tilting motion 13, the upper surface 9 of the movable part 3 is oriented perpendicular to the vertical direction z and thus parallel to the secondary winding structure. This provides a desired orientational alignment between the primary winding structure in the movable part 3 and the secondary winding structure in the receiving device 11.

Claims

1. An inductive power transfer pad, in particular a power transfer pad (1) of a system for inductive power transfer to a vehicle, comprising a stationary part (2) and a movable part (3), wherein the stationary part (2) has a bottom surface (4), wherein the movable part (3) has an upper surface (7), wherein the movable part (3) is movable between a retracted state and an extended state, characterized in that at least a portion of the upper surface (7) is inclined with respect to the bottom surface (4) in the retracted state of the movable part (3).

2. The inductive power transfer pad according to claim 1, characterized in that the at least one portion of the upper surface (7) is oriented parallel to the bottom surface (4) in the extended state of the movable part (3).

3. The inductive power transfer pad according to one of the preceding claims, characterized in that the stationary part (2) provides a first contact section (1 Oa) for a first border section of the movable part (3) and a second contact section (10b) for a second border section of the movable part (3), wherein one of the contact sections (10a) is arranged lower than the remaining contact section (10b).

4. The inductive power transfer pad according to claim 3, characterized in that the second contact (10b) section is stepped.

5. The inductive power transfer pad according to one of the preceding claims, characterized in that the power transfer pad (1) comprises at least one motion guiding means, wherein the motion guiding means is designed and/or arranged such that the movable part (3) executes a tilting motion when moved from the retracted state to the extended state.

6. The inductive power transfer pad according to claim 5, characterized in that the movable part (3) executes the tilting motion at the beginning of the movement from the retracted state to the extended state.

7. The inductive power transfer pad according to one of the preceding claims, characterized in that the power transfer pad (1) comprises a primary winding structure, wherein the primary winding structure is arranged parallel to the upper surface (7).

8. The inductive power transfer pad according to one of the preceding claims, characterized in that the power transfer pad (1) comprises at least one carrier plate for at least one foreign object detection means, wherein the at least one carrier plate is arranged parallel to the upper surface (7).

9. The inductive power transfer pad according to claim 8, characterized in that the object detection means comprises at least one winding structure.

10. An inductive power transfer system, in particular for an inductive energy transfer to a vehicle, comprising an inductive power transfer pad (1) according to one of the claims 1 to 9, and at least one receiving device for receiving an alternating electromagnetic field generated by a primary winding structure of the inductive power transfer pad (1).

11. A method of operating an inductive power transfer pad (1), wherein the power transfer pad (1) comprises a stationary part (2) and a movable part (3), wherein the movable part (3) comprises a primary winding structure, wherein the movable part (3) is movable between a retracted state and an extended state, wherein the stationary part has a bottom surface (4), wherein the movable part (3) has an upper surface (7), characterized in that at least a portion of the upper surface (7) is inclined with respect to the bottom surface (4) in the retracted state of the movable part (3).

12. The method according to claim 11, characterized in that the movable part (3) executes a tilting motion when moved from the retracted state to the extended state.

13. The method according to claim 11 or 12, characterized in that the movable part (3) executes the tilting motion before executing a translational motion when moved from the retracted state to the extended state.