Eddy current brakes for linear drives

Abstract

A linear eddy current brake (WBS) consists of at least one brake plate 14 and at least one moving rotor with a magnet, whose magnetic surface 12 generates induction in the brake plate 14 and induces eddy currents 23 around the magnetic surface. The invention is characterized in that the brake plate is divided by slots 19 in the brake plate into open segments 20 which are insulated from each other and reduce the braking force of the WBS. The open segments 10 can be electrically connected or short-circuited as required to increase the braking force of the WBS. The eddy currents in a segmented brake plate (S-brake plate) therefore flow only in the respective open segments and in the conductor areas 9 which connect the open segments on one side. The basic feature of the device for implementing the method is therefore that the S-brake plate is functionally divided into a fixed area 11, a contact area 24, an induction area 10 and a conductor area 9, and that the area of ​​the S-brake plate, except for the conductor areas 9, is divided into a number of segments 20 which can be short-circuited as required by transversely extending slots 19.

Description

[Technical field]

[0001] Eddy current brakes for linear drives (WBS) are used in the cabins of roller coasters or for linear drives in so-called free-fall towers. The WBS brakes the vehicle at the end of the ride in a fail-safe manner, as described in German utility model no. 29506374.

[0002] The WBS eddy current brake consists of a short, axially moving rotor with magnets and a fixed, solid brake plate mounted between the magnets.

[0003] The large brake plates make it difficult to accelerate the cars at the start of a new train service. Therefore, the brake plates are extended from the space between the magnets. The mechanical device for extending the large brake plates is complicated and expensive. This document provides a new method that can change the braking force of the WSB without contracting or extending the brake plates. [Background technology]

[0004] FIG. 1 shows a front view of a vortex brake for a linear drive according to the prior art.

[0005] The vortex-current brake WBS consists of a brake plate 1 and a U-shaped slider 2 with two magnetic strips 3 carrying magnets 4 between which an induction space 5 is formed, and a perpendicular mounting profile 6 fastens the brake plate 1 to a fixed platform 7. The slider 2 moves along a movement axis (linear axis). The three dimensions of the brake plate 1 are defined with respect to the linear axis (movement axis) of the slider as follows:

[0006] The length of the brake plate 1 is oriented axially (along a linear axis, i.e. here perpendicular to the drawing plane), the height of the brake plate 1 is oriented laterally (i.e. in the drawing plane from bottom to top) and the width (thickness) of the brake plate 1 is oriented laterally (i.e. in the drawing plane horizontally from left to right).

[0007] The magnet has a magnet width b m and magnet height h m and magnetic induction B m The magnet area is defined as the product b m h m The magnets are magnetized alternately along the magnetic strip 3, i.e. from bottom to top in the drawing plane of Fig. 1. The opposing magnets 4 have equal polarity, and the induction of the opposing magnets 4 increases the induction space.

[0008] The brake plate is usually made of a copper alloy and is approximately 6 mm thick, approximately 40 cm high and approximately 60 cm long. The prior art brake plate 1 has a solid design.

[0009] 2 shows a side view of a solid brake plate 1, showing three magnetic surfaces 12 and three eddy currents 13. The brake plate 1 is functionally divided into an inductive region 10, a conductor region 9 and a profile region 11.

[0010] The dashed area 13 is the magnetic induction B m The moving magnet induces a ring-shaped eddy current 13 which surrounds the magnetic surface 12 and slows down the slider.

[0011] A ring-shaped eddy current 13 is excited in the induction region 10 and is short-circuited by the conductor region 9 and the profile region 11. Equation (1) expresses the braking force F WS for and eddy currents in solid brake plates I WS holds as a first approximation for: F WS ~I WS ~Bm b m 2 h m (1)

[0012] Braking force F of solid brake plate 1 WS and eddy current I WS is the magnetic induction of the magnet B m , the square of the width B m 2 and height h m is proportional to.

[0013] The existing technical solution is magnetic induction B m We exploit the dependence of the braking force on , see equation (1).

[0014] The method according to EP 3452516 has a magnet width b m It is proposed to move the magnetic strip of the slide axially only.

[0015] The inductions of the magnets facing each other in the induction space are no longer equal, but opposite, after the magnetic bar is moved. The inductions of the magnets in the induction space cancel each other out, and the damping force is reduced. If the magnetic strip is smaller than the magnet width b m When the number is returned, the induction B in the induction space m increases, and the braking force of the vortex brake WBS increases.

[0016] In US Patent 4,482,034 it is proposed to rotate some of the magnetic poles and thus adjust their braking effect. In German Patent No. 1053687 of the German Patent Office a linear movement of magnets similar to patent specification EP 451516 is proposed. In Chinese Patent Application Publication No. 105591523 the rotating disk is slowed down by superimposing the magnetic field of the magnetic poles with the magnetic field of a current carrying coil. By changing the current direction in the coil the magnetic flux and therefore the braking effect of the magnetic poles is increased, decreased or switched off. In another way the braking force is changed by contracting or extending the brake plate from the induction chamber. If the solid brake plate is outside the induction chamber there is no braking force, the further the brake plate is brought into the induction chamber the greater the braking force of the solid brake plate.

[0017] The pressure accumulator and the valve are arranged in such a way that in the event of a failure the brake plates are retracted into the induction chamber so that the full braking force is available in the event of a failure (Fail-Safe WBS). The energy required in the event of a failure is provided by the pressure accumulator.

[0018] In the following, the above mentioned prior art is critically evaluated. The device for moving the magnetic strip (European Patent Application No. 3451516, U.S. Patent No. 4,482,034) is complicated and expensive due to the strong attractive forces between the magnetic strips. This device requires energy in the vehicle, which is not available in the cab of the roller coaster. For this reason, this method has not taken root.

[0019] Controlling the braking effect of the poles using current carrying coils is problematic because the coils are very large and the coil currents cause losses and high temperatures. Moreover, this method is only aimed at rotating eddy current brakes. The device for contracting and extending the brake plates consists of a pneumatically or hydraulically actuated cylinder with a pressure accumulator. This device must be able to absorb the full braking force and is therefore complex, bulky and expensive.

[0020] This criticism also applies to the pressure accumulator required as an energy source to force the brake plate into the induction chamber. [Prior art documents] [Patent documents]

[0021] [Patent Document 1] German Utility Model No. 29506374 [Patent Document 2] European Patent Application Publication No. 3452516 [Patent Document 3] U.S. Patent No. 4,482,034 [Patent Document 4] German patent no. 1053687 [Patent Document 5] China Patent Application Publication No. 105591523 Summary of the Invention [Problem to be solved by the invention]

[0022] Considering these drawbacks of known designs, the object of the present invention is to establish a method for controlling the braking force of a WBS that does not require costly movement of brake plates.

[0023] A further object is to specify such an apparatus as is required for the implementation of the invention. A further object is to achieve a ratio of maximum to minimum braking force of the controlled WSB of at least 9. A further object is to design the apparatus compactly so as to make it possible to replace an existing WSB with a WSB controlled according to the invention.

[0024] These devices are intended to create short circuits between segments of the S brake plates or to extinguish these short circuits. A further object of the invention is to define the characteristics and the topology of the brake plates of the WBS to be controlled.

[0025] The device for controlling the brake plates should switch on and off currents in the range of several thousand A and the resistance of a short circuit should be only a few milliohms. High losses and unacceptably high temperatures should be avoided.

[0026] If possible, the device should be able to withstand up to 10 5 The device should also be fail-safe, i.e. maximum braking force should be developed in the event of a failure. [Means for solving the problem]

[0027] The solution to the technical problem lies in a method according to the features of claims 1 to 3. The method can be implemented by an apparatus according to claims 4 to 14. Thus, according to the invention, a solid brake plate is divided into segments. These segments are short-circuited to achieve a high braking force or the short-circuit is opened to reduce the braking force. The topology of the segmented grey substrate and the apparatus required to generate and eliminate short-circuits between the segments of the brake plate is shown below:

[0028] The drawings are used to illustrate the basic problem and show the apparatus for carrying out the method, which will be described and explained below. [Brief description of the drawings]

[0029] [Figure 1] Front view of an eddy current brake for state-of-the-art linear drives. [Diagram 2] FIG. 1 shows a state-of-the-art solid brake plate with three eddy currents. [Diagram 3] FIG. 1 illustrates a segmented brake plate with an open segment. [Figure 4] FIG. 1 illustrates a segmented brake plate with a shorted shorting surface. [Diagram 5] FIG. 2 is a diagram showing the structure of a switch. [Figure 6] FIG. 1 shows a contact conductor with a spring contact. [Figure 7] FIG. 2 shows a contact conductor with a plug contact.

[0030] The object of the invention is achieved by dividing the area of ​​a conductive brake plate into a number of insulated segments. The segmented brake plate is hereinafter referred to as an S-brake plate. The segmentation is achieved by providing slots in a solid brake plate. The slots insulate the conductive segments from each other, hereinafter referred to as open segments.

[0031] 3 shows a segmented brake plate with open segments 20. The brake plate 14 is functionally divided into a profile region 11, a guiding region 10 and a conductor region 9. The height of the guiding region 10 is 1 / 2 the magnet height h m is equal to or greater than.

[0032] The contact area 17 of the S-brake plate 14, which is arranged between the guide area 10 and the profile area 9, is divided into individual segments. The contact area 16 of one segment is shown by the shaded area 16 in Figure 3. The two actuator areas 18 are for mounting the actuators.

[0033] The slot 19 preferably extends laterally through the guiding region 10, through the contact region 17 and through the profile region 11. Only the conductor region 9 is not segmented. The slot has a segment width b s The induction area 10 of the S brake plate is covered by magnetic induction.

[0034] The contact area 17 of the S-brake plate 14 cannot short-circuit any eddy currents, since this area is interrupted by the slots 19. The eddy currents 22 can only short-circuit within the segments 20. Thus, the eddy currents 22 only surround the respective active segment faces 21, which are shown hatched in FIG. 4. The braking force F of the S-brake plate 14 with open segments 20 is WS1 and eddy current I WS1 is the segment width b S is proportional to the square of . The following holds true: F WS1 ~I WS1 ~B m b S 2 H m (2)

[0035] The more open segments 20 there are, the smaller the segment width, eddy currents and damping force.

[0036] The width of the slots 19 in the S-brake plate 14 is in the millimeter range, since the maximum voltage between two slots is less than 50 V. The slots 19 are preferably filled with an insulator to exclude impurities.

[0037] A solid brake plate having the dimensions of the S brake plate 14 is called an equivalent brake plate. The braking force of the S brake plate 14 with the open segments 20 can be reduced to less than 10% of the braking force of the equivalent brake plate.

[0038] The requirement for maximum braking force is met if the conductor area 9 of the S-brake plate 14 is not affected by the leakage flux of the rotor magnets and no eddy currents are excited. This requirement is achieved by a higher induction range than the magnets.

[0039] 4 shows the cross-hatched contact area 24 of a segmented brake plate 14 with shorted segments 20. In accordance with the invention, the braking force of the S brake plate 14 is increased when the segments 20 are shorted. The shorting of the segments 20 occurs at the contact area 24.

[0040] The eddy currents 23 in the S-brake plate 14 with the shorted segments 20 surround the magnetic surface 12, which is shown hatched in FIG. 4. The eddy currents I WS2 The curve 23 in Fig. 2 represents the eddy current I WS is equivalent to the curve

[0041] Equation (3), which is equivalent to equation (1), gives the eddy current I in the S brake plate 14 with the shorted segment 20. WS2 and braking force F WS2 This applies to: F WS2 ~I WS2 ~B m b m2 H m (3)

[0042] As a result, the braking force of an S brake plate 14 with shorted segments 20 can reach up to 90% of the braking force of a comparable brake plate.

[0043] In the following, an apparatus suitable for applying the above-mentioned method is described.

[0044] An apparatus for carrying out the method according to claims 1 to 3 comprises two switches 30 mechanically connected to two actuator areas 18 of the S-brake plate 14, as shown diagrammatically in Figure 4. One switch 30 comprises two pairs of actuators 25, as shown in Figure 5.

[0045] The pair of actuators 25 consists of an on actuator 26 and an off actuator 27 that move a contact conductor 28 with a spring contact 29. The off actuator 27 moves the contact conductor 28 with the spring contact to an off position, and the on actuator 26 moves the contact conductor 28 with the spring contact to an on position.

[0046] The segments 20 of the S-brake plate 14 are shorted by two contact conductors 28 with spring contacts 29. Two ON actuators 26 and two OFF actuators 27 attached to the actuator area 18 of the S-brake plate 14 move the two contact conductors 28 with spring contacts 29 as shown in FIG.

[0047] When the two ON actuators 26 of the S-brake plate 14 move the two contact conductors 28 to the ON position, the spring contacts 29 press against both contact areas of the S-brake plate 14, shorting the segments of this S-brake plate 14. This state is called the ON state. The segments 20 are shorted in this state, as shown in Figure 5.

[0048] When the two off actuators 27 of the S-brake plate 14 move the two contact conductors 28 to the off position, the connection between the spring contacts 29 and the segment 20 is interrupted. This opens the short circuit of the segment 20. This state is called the off state. The segment 20 is open in the off state. The on and off switches of the S-brake plate 14 are controlled synchronously.

[0049] 5, a housing 31 secures the actuator pair 25 of the S-brake plate 14 to a fixed platform 7. The S-brake plate 16 is fastened to a fastening profile 6 by means of fastening screws 8. The fastening profile 6 secures the S-brake plate 14 to the platform 8.

[0050] The fastening profile 6 and the fastening screws 8 are insulated from the S-brake plate 14. This prevents the fastening profile 6 from shorting out the segments 20 of the S-brake plate 14.

[0051] 6 shows the construction of a contact conductor 28 connected to a plurality of individually spring-loaded contacts 29. The contact conductor 28 includes an actuator region 33 at each of two ends for attachment of an actuator. The contact conductor 28 is formed from a highly conductive metal (e.g., copper). The spring contacts 29 are formed from a highly conductive spring steel (e.g., bronze).

[0052] 7 shows an embodiment of a contact conductor 32 with two rows of individually spring-loaded plug-in contacts 34 with two actuator areas 33 provided for fastening an actuator. An S-brake plate is then fastened between the plug-in contacts 34.

[0053] The contact surfaces of the segments of the S-brake plate, when used in a contact conductor with plug-in contacts 34, are divided into conductive and insulated contact surfaces. The insulated contact surfaces are covered by an insulating layer.

[0054] In the OFF state, the plug contacts 34 contact only the insulated contact surfaces and the segments remain insulated from each other. In the ON state, the plug contacts 34 contact the conductive contact surfaces of the segments, shorting the segments.

[0055] The two on-adjusters move the plug contacts 34 to the conductive contact surfaces of the segments, and the off-adjusters move the plug contacts 34 to the insulated contact surfaces of the segments.

[0056] The spring contacts 29, the plug contacts 34 and the contact surfaces of the segments 16 are covered with contact material. The slots between the spring contacts 29 and the plug contacts 34 are filled with an insulator. The slots 19 of the S-brake plate are filled with an insulator to exclude conductive contamination. The on- and off-actuators can be realized by electromechanical, pneumatic or hydraulic actuators or by pneumatic or hydraulic cylinders for their actuation. The actuators are preferably designed with pneumatic or hydraulic cylinders for their movement.

[0057] The pressure accumulators and valves for actuating hydraulic or pneumatic on and off actuators are configured such that the segments of the S brake plate are shorted in the event of a failure.

[0058] The ON actuator of the fail-safe switch can be replaced or extended by one or more tension springs. In the event of a fault, the OFF actuator is deactivated and the tension springs automatically move the contact conductors to the ON position.

[0059] The off actuator of the switch can be replaced with or extended by one or more compression springs, while the on actuator remains unchanged.

[0060] The two contact conductors of the S-brake plate are moved synchronously to the on or off position (Claim 13).

[0061] Position sensors are provided that report when the contact conductors have reached the ON or OFF positions. Temperature sensors also register and report when the temperature of the spring or plug-in contacts has reached a maximum value. This prevents the spring or plug contacts from being welded to the segments. [Explanation of symbols]

[0062] 1 Brake plate 2 Runner 3 Magnetic Strips 4. Magnets 5. Induction Room 6. Fastening Profile 7. Platform 8 Fastening screws 9 Ladder Area 10 Induction range 11 Fastening area 12 Magnetic Surface 13 Eddy current 14 S brake plate 15 - 16 Contact surface of segment 20 17 Contact area 18 Control Range 19 Slot between segments 20 20 Segments 21 Segment Surface 22 Eddy currents in segment 20 23 Eddy Currents Around Magnetic Surfaces 24 Contact area 25 actuator pairs 26 On Adjuster 27 Off Adjuster 28 Contact Manager 29 Spring Contacts 30 Switch 31 Housing 32 contact conductor with two rows 15 of individually spring-loaded plug contacts 33 Control Range 34 Plug Contacts

Claims

1. A method for controlling the braking force of a linear eddy current brake (WBS), comprising at least one brake plate (14) and at least one moving rotor (2) with a plurality of magnets (4), the magnetic surfaces (12) of which generate induction in the brake plate (14) and induce eddy currents (13) around the magnetic surfaces, 1. A method for controlling the braking force of a linear eddy current brake (WBS), characterized in that a number of slots (19) in the brake plate (14) are used to segment the brake plate into a number of mutually insulated open segments (20) that reduce the braking force of the eddy current brake (WBS) compared to a continuous brake plate, and that these open segments (20) are electrically connected or shorted as required to increase the braking force of the WBS.

2. 2. The method according to claim 1, characterized in that the eddy currents (22) in the segmented brake plate (14), i.e. in a so-called S-brake plate (14), flow only in the respective open segments (20) and in conductor areas (9) connecting the open segments (20) on one side.

3. 3. The method according to claim 1 or 2, characterized in that the eddy currents (22) surround the magnetic surface (12) of the S-brake plate (14) only in the S-brake plate (14) that is provided with a shorted segment (20).

4. 4. An apparatus for carrying out the method according to any one of claims 1 to 3, comprising a linear eddy current brake (WBS) having at least one brake plate (14) and at least one moving rotor (2) with a plurality of magnets (4), the magnetic surfaces (12) of which generate induction in the brake plate (14) and induce eddy currents (13) around the magnetic surfaces, 1. A device according to claim 1, wherein said S-brake plate (14) is functionally divided into a fastening area (11), a contact area (17), a guidance area (10) and a conductor area (9), and wherein said areas of said S-brake plate (14) except for said conductor area (9) are divided by transversely extending slots (19) into a number of segments (20) which can be short-circuited as required.

5. A plurality of switches (30) are provided for shorting the segments (20) as required, each switch (30) having two pairs of actuators (25), one pair of actuators (25) located to the left of the S-brake plate (14) and one pair of actuators (25) located to the right of the S-brake plate (14), (25) located to the left or right of the S-brake plate (14), each pair of actuators (25) having an on actuator (26) and an off actuator (27), each pair of actuators (25) having 5. The device of claim 4, wherein a spring contact (29) of the contact conductor (28) can be used to move the contact conductor (28) to an on position or an off position, the spring contact (29) of the contact conductor (28) can be moved to the off position when in the on position, contacting the contact surfaces of the segments (20) to short-circuit the segments (20) when in the on position, and the spring contact (29) of the contact conductor (28) is insulated from the contact surfaces of the segments (20) by an air gap when in the off position, thereby not short-circuiting the segments (20).

6. 6. The device according to claim 4 or 5, characterized in that there is a fastening profile (6) of the S-brake plate (14) and that the fastening screws (8) are insulated from the S-brake plate (14).

7. 7. The device according to claim 5 or 6, characterized in that the contact conductor (28) is made of a conductive material, the spring contacts (29) electrically connected to the contact conductor (28) are made of a conductive spring alloy, and a plurality of actuator regions (18) are formed at both ends of the S-brake plate (14) connected to the actuator.

8. 8. The device according to claim 5, wherein the contact conductor (32) comprises two rows of individually spring-loaded plug contacts (15), two actuator areas (33) and an S-brake plate (14) interposed between the plug contacts (15), the plug contacts (15) being in contact with the contact surfaces of the segments (20) of the S-brake plate (14), the contact surfaces of the segments (20) being divided into conductive and insulated contact surfaces, the plug contacts (15) in the on position being in contact with the conductive contact surfaces and short-circuiting the segments (20) of the S-brake plate (14), whereas the plug contacts in the off position being in contact with the insulated contact surfaces of the segments (20) and thereby not short-circuiting the segments (20).

9. 9. The device according to claim 5, wherein the spring contacts (29), the plug contacts (15) and the contact surfaces of the segments (20) are coated with a contact material and the slots (19) are filled with an insulator.

10. 10. Apparatus according to any one of claims 5 to 9, characterised in that each on actuator (26) and each off actuator (27) comprises a pneumatically or hydraulically controlled cylinder for its actuation.

11. Device according to any one of claims 5 to 10, characterized in that each on-actuator (26) is designed with one or more springs for its movement.

12. Device according to any of the following claims 5 to 11, characterized in that each off actuator (27) is designed with one or more springs for its movement.

13. 13. The device according to claim 5, characterized in that the contact conductors (28) of the S-brake plates (14) can be synchronously conveyed to the on or off state and all segments (20) of the S-brake plates (14) can be synchronously shorted or opened.

14. 14. The device according to claim 5, characterized in that there are a number of position sensors by means of which the reaching of the on and off positions of the contact conductor (28) can be registered, and there are a number of temperature sensors for detecting the temperature of the spring contacts (29).

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