Brake mechanism and unmanned aerial vehicle

Abstract

The invention discloses a braking device and an unmanned aerial vehicle, and the unmanned aerial vehicle comprises a shell which is provided with a power output shaft and is also provided with a supporting plate; the enclasping piece is arranged on a shaft body of the power output shaft, and a groove is formed in the periphery of the enclasping piece; the driving piece is arranged on the shell and located on the side away from the supporting plate; one end of the rocker arm is hinged to the supporting frame, the other end of the rocker arm is connected with the output end of the driving part, a speed reduction wheel is hinged to the rocker arm and used for being clamped into the groove to reduce the rotating speed of the power output shaft, and the driving part is used for driving the rocker arm to swing to enable the speed reduction wheel to be clamped into or separated from the groove. By means of the structure, the propellers can be kept in the horizontal state and do not interfere with a launcher or a parachute rope no matter the unmanned aerial vehicle is kept still, launched or stopped to land.

Description

Technical Field

[0001] The present invention relates to the technical field of drones, and particularly to a braking mechanism and a drone. Background Art

[0002] When most fixed-wing aircraft take off by rocket boost, it is necessary to solve the interference problem between the propeller and the launch rack, as well as the damage problem of the propeller by the rocket exhaust gas flow.

[0003] Generally, the propeller is fixed to solve the interference problem. Currently, there are two main ways to fix the propeller:

[0004] One is to control the propeller to be at a set angle through the excitation motor of the piston engine. After the rocket boost is completed, the engine is started to work. However, piston engines all have a certain startup success rate. After boosting the fixed-wing aircraft, the time left for the piston engine to start is not much.

[0005] The other is to install a propeller locking mechanism on the piston engine and use it in conjunction with a clutch. This clutch needs to reach a certain rotational speed of the piston engine to connect the propeller. During the rocket boost stage, the piston engine is in an idle state, and the propeller is locked by the locking mechanism and waits to unlock the propeller after the boost is completed. However, the commonly used propeller locking mechanisms at present can only unlock the propeller and cannot re-lock the propeller after unlocking. For drones that rely on parachutes to land, there is a risk that the propeller hits the parachute rope and the propeller breaks when it touches the ground during the landing stage. Summary of the Invention

[0006] The present invention provides a braking mechanism and a drone, aiming to solve at least one of the technical problems existing in the prior art.

[0007] The first aspect of the present invention aims to provide a braking mechanism, including:

[0008] A housing, provided with a power output shaft, and a support plate is also provided on the housing;

[0009] A clamping member, arranged on the shaft body of the power output shaft, and a groove is provided on the outer periphery of the clamping member;

[0010] A driving member, arranged on the housing and located on the side away from the support plate;

[0011] A rocker arm, one end of which is hinged to the support frame, and the other end is connected to the output end of the driving member. A reduction gear is hinged on the rocker arm, and the reduction gear is used to be clamped into the groove to reduce the rotational speed of the power output shaft. The driving member is used to drive the rocker arm to swing so that the reduction gear is clamped into or disengaged from the groove.

[0012] According to some embodiments of the present invention, an elastic component is further included. The elastic component is arranged between the rocker arm and the output end of the driving member. When the rocker arm is in the clamping position, the elastic component is used to keep the rocker arm always close to the clamping member.

[0013] According to some embodiments of the present invention, the elastic component includes:

[0014] a first connecting rod, one end of which is hinged to the output end of the driving member;

[0015] a fixed block, movably provided on the rod body of the first connecting rod and hinged to the rocker arm at its side;

[0016] A spring is provided on the rod body of the first connecting rod. When the rocker arm is in the clamping position, the spring is used to ensure that the fixing block always maintains a tendency to move toward the direction of the clamping member.

[0017] According to some embodiments of the present invention, the reduction wheel is configured as a ball bearing.

[0018] According to some embodiments of the present invention, a baffle is provided at the other end of the first connecting rod, and the spring is configured as a compression spring, with both ends of the compression spring respectively connected to the baffle and the fixing block.

[0019] According to some embodiments of the present invention, a baffle or a block is provided at one end of the first connecting rod, and the spring is configured as a tension spring, with both ends of the tension spring respectively connected to the baffle and the fixed block, or respectively connected to the block and the fixed block.

[0020] According to some embodiments of the present invention, a torsion spring is provided at the hinge point where the rocker arm is hinged to the support frame. When the rocker arm is in the clamping position, the torsion spring is used to keep the rocker arm always close to the clamping member.

[0021] According to some embodiments of the present invention, there are two rocker arms, and there are two corresponding grooves on the clamping member. A second connecting rod is provided at the output end of the driving member, the middle part of the second connecting rod is connected to the output end of the driving member, and a rocker arm is hinged at each end.

[0022] According to some embodiments of the present invention, the two grooves are respectively provided on both sides of the clamping member, and a plane formed between the central axes of the two grooves is parallel to a horizontal plane.

[0023] The second aspect of the present invention provides a drone comprising a braking mechanism as described in any one of the above items.

[0024] The beneficial effects of the present invention are as follows:

[0025] 1. When stationary, the driving part is started to drive the rocker arm to swing to the clamping position, and the propeller is moved to make the reduction wheel stuck in the groove, so that the propeller always remains stationary; when decelerating, the driving part is started to drive the rocker arm to swing to the clamping position, and the reduction wheel is pressed against the outer periphery of the clamping part until the speed decreases to the point where the reduction wheel is stuck in the groove. The power output shaft can no longer drive the clamping part to rotate, causing the groove to disengage the reduction wheel. At this time, the reduction wheel is stuck in the groove, keeping the propeller stationary. To disengage the reduction wheel from the groove, it is only necessary to increase the speed of the power output shaft. In this way, the propeller can remain fixed whether the drone is stationary until launch or during landing, and will not interfere with the launch pad or parachute rope. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is an overall schematic diagram of the clutch mechanism and brake mechanism according to an embodiment of the present invention;

[0027] Figure 2 for Figure 1 A side cross-sectional view of the clutch mechanism shown;

[0028] Figure 3 A cross-sectional view of the second rotor end surface of the clutch mechanism according to an embodiment of the present invention;

[0029] Figure 4 2 is a cross-sectional view of a brake mechanism according to an embodiment of the present invention.

[0030] Figure Number:

[0031] Housing 100, support plate 110;

[0032] Connector 200;

[0033] a first rotor 300;

[0034] Second rotor 400, base 410, rotating shaft 411, friction plate 420, first end 421, second end 422, stepped recess 423, fixing post 424, connecting seat 425, elastic member 430, upper cover 440;

[0035] Power take-off shaft 500;

[0036] Paddle seat 600, groove 610;

[0037] Driving member 700, connecting rod 710;

[0038] Rocker arm 800, reduction wheel 810;

[0039] Elastic component 900 , first connecting rod 910 , fixing block 920 , spring 930 , baffle 940 . DETAILED DESCRIPTION

[0040] The following content will describe several embodiments of the present invention, including the embodiments corresponding to the attached drawings. It can be understood that the attached drawings are used to assist in understanding the technical features and technical solutions of the present invention, and should not be construed as limiting the protection scope of the present invention.

[0041] The following will clearly and completely describe the concept, specific structure, and technical effects generated by the present invention in combination with the embodiments and the attached drawings, so as to fully understand the purpose, solution, and effects of the present invention. It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other.

[0042] It should be noted that unless otherwise clearly defined, when a certain feature is referred to as "fixed", "connected", "installed", "set" on another feature, it can be directly "fixed", "connected", "installed", "set" on another feature, or indirectly "fixed", "connected", "installed", "set" on another feature. The words such as "fixed", "connected", "installed", "set" should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above words in the present invention in combination with the specific content of the technical solution.

[0043] It should be noted that the description of the orientation or positional relationship indicated by up, down, left, right, top, bottom, front, back, inside, outside, etc. in the present invention is based on the orientation or positional relationship of the attached drawings or embodiments, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation of the present invention.

[0044] It should be noted that the term "and / or" used in the present invention includes any combination of one or more of the related listed items. The meaning of several is one or more, the meaning of multiple is at least two, and understandings such as greater than, less than, exceeding, etc. do not include the present number, and understandings such as above, below, within, etc. include the present number.

[0045] It should be noted that if the present invention describes the first and the second, it is only for the purpose of distinguishing technical features, and cannot be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence relationship of the indicated technical features.

[0046] It should be noted that unless otherwise clearly defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art of this technology. The terms used in the description of this specification are only for describing specific embodiments, rather than for limiting the present invention.

[0047] Refer to Figures 1 to 4, an object of the first aspect of the present invention is to provide a clutch mechanism, comprising: a housing 100; a connecting member 200 disposed in the housing 100 for connecting an engine; a first rotor 300 having an inner cavity, the first rotor 300 being rotatably disposed in the housing 100 for connecting a propeller base 600; a second rotor 400 located in the inner cavity of the first rotor 300, including a base 410 and a plurality of friction plates 420, the base 410 being connected to the connecting member 200, a first end 421 of the friction plate 420 being movably connected to the base 410, a second end 422 being provided with an elastic member 430 for separating the second end 422 from the inner wall of the first rotor 300, and the second end 422 being able to fit against the inner wall of the first rotor 300 to cause the first rotor 300 to rotate.

[0048] Applying the above clutch mechanism, at least has the following beneficial effects: the first end 421 of the friction plate 420 is movably disposed on the base, and the second end 422 is provided with an elastic member. When the engine rotates at a low speed, the centrifugal force generated is less than the elastic force of the elastic member. At this time, the second end 422 of the friction plate 420 cannot fit against the inner wall of the first rotor 300 under the action of the elastic member and cannot drive the first rotor 300 to rotate synchronously. The propeller stop mechanism on the propeller base 600 can lock the propeller. When the engine rotates at a high speed, the centrifugal force generated is greater than the elastic force of the elastic member. At this time, the second end 422 of the friction plate 420 fits against the inner wall of the first rotor 300 under the action of the centrifugal force, driving the first rotor 300 to rotate, thereby driving the propeller base 600 to rotate. After the power is transmitted to the propeller, it provides flight power for the drone, maintaining power transmission while ensuring that the propeller can remain stationary at low speed and idle speed and will not interfere with the launch rack.

[0049] According to some embodiments of the present invention, a plurality of friction plates 420 are provided, and the plurality of friction plates 420 are arranged in a circumferential array around the central axis of the base 410. The circumferential array arrangement can make the centrifugal forces generated by the plurality of friction plates 420 equal, and the pressures and frictional forces generated by the plurality of friction plates 420 on the inner wall of the first rotor 300 equal, ensuring the accuracy and stability of power transmission.

[0050] According to some embodiments of the present invention, a connecting seat 425 extends inward from the first end 421 of the friction plate 420, and two ends of the elastic member 430 are respectively connected to the second end 422 of the friction plate 420 and the connecting seat 425 of the adjacent friction plate 420. By extending the connecting seat 425 inward to connect the elastic member 430, interference friction between the elastic member 430 and the main body of the friction plate 420 is avoided, thereby preventing wear of the elastic member 430.

[0051] In this embodiment, the elastic member 430 is configured as a tension spring. Under the action of the tension spring, the second end 422 of the friction plate 420 always remains contracted inward, so that the outer wall of the friction plate 420 does not contact the inner wall of the first rotor 300, thereby blocking the transmission of power. When the engine drives the connecting member 200 to rotate at high speed, the centrifugal force generated exceeds the elastic force of the tension spring. At this time, the second end 422 of the friction plate 420 swings outward under the action of centrifugal force, and the outer wall of the friction plate 420 fits against the inner wall of the first rotor 300, so that the second rotor 400 can rotate with the first rotor 300, completing power transmission.

[0052] According to some embodiments of the present invention, the second rotor 400 further includes an upper cover 440, and a plurality of rotating shafts 411 are provided on the base 410, with the two ends of the rotating shafts 411 respectively connected to the base 410 and the upper cover 440, and the first end 421 of the friction plate 420 is hinged to the rotating shaft 411. The first end 421 of the friction plate 420 can rotate around the rotating shaft 411 on the base 410, so that the second end 422 can swing inward to disengage from the inner wall of the first rotor 300, or swing outward to fit the inner wall of the first rotor 300.

[0053] According to some embodiments of the present invention, the second end 422 of the friction plate 420 is provided with a step recess 423, and a fixing column 424 is provided on the step recess 423. One end of the elastic member 430 is connected to the fixing column 424, and the elastic member 430 is sunk below the end surface of the friction plate 420 through the step recess 423 to avoid interference with other structures.

[0054] According to some embodiments of the present invention, an annular groove is provided on the upper cover 440, and the end of the fixing column 424 away from the step recess 423 is inserted into the annular groove. In order to avoid the fixing column 424, the annular groove also serves as a guide for the rotation of the second end 422 of the friction plate 420.

[0055] According to some embodiments of the present invention, the connecting member 200 is connected to the upper cover 440 through gear meshing, and the gear meshing connection can ensure the accuracy of power transmission. In addition to this embodiment, in some other embodiments, it is also possible to set flat keys, splines and other structures on the connecting member 200, set keyways at the corresponding connections of the upper cover 440, or set some other structures that can achieve power transmission.

[0056] According to some embodiments of the present invention, a power output shaft 500 is further included. The power output shaft 500 is disposed in the housing 100 and fixedly connected to the first rotor 300 . An end of the power output shaft 500 away from the first rotor 300 is connected to the propeller seat 600 .

[0057] In this embodiment, the housing 100 is installed on the outer shell of the engine. The connecting member and the engine output shaft are connected by a tapered surface and a flat key and then installed and connected by fasteners. The first rotor 300 and the power output shaft 500 are installed and connected by fasteners. A bearing is provided between the power output shaft 500 and the housing 100, and a bearing is also provided between the paddle base 600 and the housing 100. The paddle base and the power output shaft 500 are connected by gear meshing and then installed and connected by fasteners. In this embodiment, the paddle base 600 also serves as the clamping member in the braking mechanism described below.

[0058] Referring to Figures 1 to 4 , the second aspect of the present invention aims to provide a braking mechanism, including: a housing 100 provided with a power output shaft 500, and a support plate 110 is further provided on the housing 100; a clamping member provided on the shaft body of the power output shaft 500, and a groove 610 is provided on the outer periphery of the clamping member; a servo 700 provided on the housing 100 and located on the side away from the support plate 110; a rocker arm 800, one end of which is hinged to the support frame and the other end is connected to the output end of the servo 700. A reduction gear 810 is hinged on the rocker arm 800, and the reduction gear 810 is used to be inserted into the groove 610 to stop the power output shaft 500 from rotating. The servo 700 is used to drive the rocker arm 800 to swing so that the reduction gear 810 is inserted into or disengaged from the groove 610; wherein, when the reduction gear 810 is inserted into the groove 610, the propeller connected to the power output shaft 500 remains in a horizontal state.

[0059] Applying the above braking mechanism has at least the following beneficial effects: When at rest, the propeller is toggled to the horizontal state and the servo 700 is started to drive the rocker arm 800 to swing to the clamping position. At this time, the reduction gear 810 is inserted into the groove 610 to keep the propeller in the horizontal state all the time; when decelerating, the servo 700 is started to drive the rocker arm 800 to swing to the clamping position, and the reduction gear 810 is pressed against the outer periphery of the clamping member until the speed is reduced to the point where the reduction gear 810 is inserted into the groove 610, and the power output shaft 500 cannot continue to drive the clamping member to rotate to disengage the groove 610 from the reduction gear 810. At this time, the reduction gear 810 is stuck in the groove 610 to keep the propeller in the horizontal position. To disengage the reduction gear 810 from the groove 610, only the speed of the power output shaft 500 needs to be increased. This enables the propeller of the drone to remain in the horizontal state during both the period of remaining stationary until launch or during landing, without interfering with the launch rack or the parachute rope; at the same time, during deceleration and shutdown during flight, even if the reduction gear 810 is not in the groove 610 at this time, during the gliding process, the wind force will cause the propeller to rotate until the reduction gear 810 is inserted into the groove 610, and then the wind force is not sufficient to cause the reduction gear 810 to disengage from the groove 610, and the propeller remains in the horizontal position.

[0060] According to some embodiments of the present invention, it further includes an elastic component 900. The elastic component 900 is arranged between the output end of the rocker arm 800 and the servo 700. When the rocker arm 800 is in the clamping position, the elastic component 900 is used to keep the rocker arm 800 always in a tendency to be close to the clamping member. The elastic component 900 includes: a first connecting rod 910, one end of which is hinged to the output end of the servo 700; a fixed block 920, which is movably arranged on the rod body of the first connecting rod 910 and is laterally hinged to the rocker arm 800; a spring 930, which is arranged on the rod body of the first connecting rod 910. When the rocker arm 800 is in the clamping position, the spring 930 is used to keep the fixed block 920 always in a tendency to move towards the direction close to the clamping member. When the servo 700 drives the rocker arm 800 to the clamping position, under the action of the spring 930, the reduction gear 810 always abuts against the outer peripheral wall of the clamping member. When the power output shaft 500 drives the clamping member to rotate to a position where the groove 610 corresponds to the reduction gear 810, under the action of the spring 930, the reduction gear 810 is pushed into the groove 610. When the rotational speed of the power output shaft 500 is still relatively high, the clamping member continues to rotate, causing the groove 610 to disengage from the reduction gear 810 and continue to rotate. At this time, the rocker arm 800 swings back, and the fixed block 920 moves away from the clamping member on the first connecting rod 910. The spring 930 plays a buffering role for the fixed block 920, preventing the swinging force from directly being transmitted back to the servo 600 and causing damage to the servo 700. At the same time, during the above process, a frictional force is generated between the fixed block 920 and the first connecting rod 910, and this part of the frictional force can offset part of the energy of the power output shaft 500. When the energy generated by the power output shaft 500 is not sufficient to cause the groove 610 to eject the reduction gear 810, that is, not sufficient to overcome the above-mentioned frictional force and the elastic force of the spring 930, the reduction gear 810 will stay in the groove 610, the power output shaft 500 will stop rotating, completing the braking of the power output shaft 500 and keeping the propeller in the horizontal position.

[0061] In the above embodiment, the reduction gear 810 is set as a ball bearing. That is, the deceleration effect is achieved through the frictional force between the fixed block 920 and the first connecting rod 910, and the elastic force of the spring 930. The reduction gear 810 is used to transmit the energy of the power output shaft 500. In some other embodiments, the reduction gear 810 can also be directly set as a runner with a rough surface to further decelerate and brake the power output shaft 500.

[0062] According to some embodiments of the present invention, a baffle 940 is provided at the other end of the first connecting rod 910. The spring 930 is a compression spring, and the two ends of the compression spring are respectively connected to the baffle 940 and the fixed block 920. When in the clamping position, that is, during the braking operation, under the action of the servo 700, the reduction wheel 810 fits on the outer peripheral wall of the clamping member. At this time, the fixed block 920 and the baffle 940 compress the compression spring by a certain amount, so that the compression spring generates a certain elastic force to ensure that the reduction wheel 810 fits on the outer peripheral wall of the clamping member, and at the same time, the compression spring also has a certain buffering effect.

[0063] According to some embodiments of the present invention, a baffle 940 or a stop block is provided at one end of the first connecting rod 910. The spring 930 is a tension spring, and the two ends of the tension spring are respectively connected to the baffle 940 and the fixed block 920, or are respectively connected to the stop block and the fixed block 920. When in the clamping position, that is, during the braking operation, under the action of the servo 700, the reduction wheel 810 fits on the outer peripheral wall of the clamping member. At this time, the tension spring between the fixed block 920 and the baffle 940 or the stop block is stretched, and the elastic force generated by the rebound of the tension spring ensures that the reduction wheel 810 fits on the outer peripheral wall of the clamping member, and at the same time, the tension spring can also generate a certain buffering effect.

[0064] According to some embodiments of the present invention, a torsion spring is provided at the hinge point where the rocker arm 800 is hinged to the support frame. When the rocker arm 800 is in the clamping position, the torsion spring is used to keep the rocker arm 800 always in a tendency to approach the clamping member. The function of the torsion spring is the same as that of the above-mentioned compression spring, and will not be elaborated here.

[0065] According to some embodiments of the present invention, there are two rocker arms 800, and two corresponding grooves 610 are provided on the clamping member. The output end of the servo 700 is provided with a second connecting rod 710. The middle of the second connecting rod 710 is connected to the output end of the servo 700, and the two ends are respectively hinged to a rocker arm 800. Through the two rocker arms 800, the braking effect can be more obvious and the braking process can be more efficient. At the same time, it can also ensure that when one of the rocker arms 800 fails, there is still a rocker arm 800 that can perform deceleration braking. In some other embodiments, according to the actual situation and the needs of the actual structure, multiple rocker arms 800 can also be set to further improve the deceleration braking efficiency.

[0066] According to some embodiments of the present invention, the two grooves 610 are respectively provided on both sides of the clamping member, and the plane formed between the central axes of the two grooves 610 is parallel to the horizontal plane.

[0067] An object of the third aspect of the present invention is to provide an unmanned aerial vehicle, including the clutch mechanism and the braking mechanism as described in any one of the above.

[0068] It should be noted that in this specification, several embodiments of the present invention may be described by terms such as "one embodiment", "some embodiments", "basic embodiment", "extended embodiment", etc. The specific features, structures, materials or characteristics in several embodiments may be combined under the premise of conforming to the principles and purposes of the present invention.

[0069] Although some embodiments of the present invention have been shown and described in this specification, the present invention should not be limited to the above embodiments. As long as it achieves the technical effects of the present invention by the same or equivalent means, all changes, modifications, equivalent replacements and equivalent variations of these embodiments within the spirit and principles of the present disclosure, without departing from the principles and purposes of the present invention, should be included within the scope of protection of the present disclosure and should be considered to be within the scope of protection of the present invention.

Claims

1. A braking mechanism, characterized in that, Comprising: A housing, provided with a power output shaft, and further provided with a support plate on the housing; A clamping member, disposed on the shaft body of the power output shaft, and a groove is provided on the outer periphery of the clamping member; A driving member, disposed on the housing and on a side away from the support plate; A rocker arm, one end of which is hinged to the support frame, and the other end is connected to the output end of the driving member. A reduction gear is hinged to the rocker arm, and the reduction gear is used to be inserted into the groove to reduce the rotational speed of the power output shaft. The driving member is used to drive the rocker arm to swing so that the reduction gear is inserted into or disengaged from the groove.

2. The braking mechanism according to claim 1, wherein, It further includes an elastic component, which is disposed between the rocker arm and the output end of the driving member. When the rocker arm is in the clamping position, the elastic component is used to make the rocker arm always keep a tendency to be close to the clamping member.

3. A braking mechanism according to claim 2, characterized in that, The elastic component includes: A first connecting rod, one end of which is hinged to the output end of the driving member; A fixed block, movably disposed on the rod body of the first connecting rod, and the side surface is hinged to the rocker arm; A spring, disposed on the rod body of the first connecting rod. When the rocker arm is in the clamping position, the spring is used to make the fixed block always keep a tendency to move in a direction close to the clamping member.

4. A braking mechanism according to claim 3, characterized in that, The reduction gear is set as a ball bearing.

5. A braking mechanism according to claim 3, characterized in that, A baffle is provided at the other end of the first connecting rod, the spring is set as a compression spring, and the two ends of the compression spring are respectively connected to the baffle and the fixed block.

6. A braking mechanism according to claim 3, characterized in that, A baffle or a stop block is provided at the one end of the first connecting rod, the spring is set as a tension spring, and the two ends of the tension spring are respectively connected to the baffle and the fixed block, or respectively connected to the stop block and the fixed block.

7. A braking mechanism according to claim 1, characterized in that A torsion spring is provided at the hinge point where the rocker arm is hinged to the support frame. When the rocker arm is in the clamping position, the torsion spring is used to make the rocker arm always keep a tendency to be close to the clamping member.

8. A braking mechanism according to any one of claims 1 to 7, characterized in that, There are two rocker arms, and correspondingly two grooves are provided on the clamping member. A second connecting rod is provided at the output end of the driving member. The middle of the second connecting rod is connected to the output end of the driving member, and the two ends are respectively hinged to one rocker arm.

9. A braking mechanism according to claim 8, characterized in that, The two grooves are respectively disposed on both sides of the clamping member, and the plane formed between the central axes of the two grooves is parallel to the horizontal plane.

10. A drone, characterized in that, Comprising the braking mechanism according to any one of claims 1 to 9.

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