Silent electromagnetic brake

Abstract

An electromagnetic brake (1) includes an electromagnet (2) arranged around a central axis SA; a slider (3) that moves relative to the electromagnet in a slider actuation direction when the electromagnet is actuated; and an air gap (4) provided between the electromagnet and the slider, through which a magnetic field passes when the electromagnet is actuated, wherein the slider is arranged radially inside or outside the electromagnet relative to the central axis SA. The electromagnetic brake is silent.

Description

Technical Field

[0001] The present invention relates to a silent electromagnetic brake, which can be used, for example, in a traction machine of an elevator. Background Art

[0002] Figure 8 A cross-sectional view of an electromagnetic brake 101 for a traction machine of an elevator according to the prior art is shown. The electromagnetic brake 101 includes an electromagnet having a coil 105 disposed in a flange 102 and a spring 106 disposed at the center of the coil 105. The spring 106 presses a brake lining 107 against a brake surface (not shown) which is, for example, part of a traction motor. The brake lining 107 is mounted on an armature 103 which is movable relative to the flange 102 along a shaft 108 mounted on the flange 102. In a state where the brake lining 107 presses against the brake surface, an air gap 104 exists between the flange 102 and the armature 103. When the coil 105 is energized, the electromagnet can provide an electromagnetic force to attract the armature 103 against the force of the spring 106. As a result, the brake 101 opens as the air gap 104 becomes smaller. Finally, the armature 103 will abut against the flange 102 and the air gap 104 disappears. The abutting action of the armature 103 on the flange 102 generates noise which can be noticed by people traveling in the elevator as interference.

[0003] One means of reducing this noise is to provide a damping spring which ensures slower movement of the armature 103, resulting in less noise generated by the abutting action of the armature 103. However, providing a damping spring requires the magnetic force to overcome a higher spring force for opening the brake, i.e., the force of the damping spring in addition to the force of the spring 106.

[0004] Therefore, there is a need to provide an electromagnetic brake which can operate without generating the above-mentioned noise. Summary of the Invention

[0005] According to the present invention, the above need is met by an electromagnetic brake having the features of claim 1.

[0006] The electromagnetic brake according to the present invention includes: an electromagnet arranged around a central axis; a slider movable relative to the electromagnet along a slider actuation direction when the electromagnet is actuated; and an air gap provided between the electromagnet and the slider, through which a magnetic field passes when the electromagnet is actuated. The slider is arranged radially with respect to the central axis inside or outside the electromagnet.

[0007] The above central axis can be understood as the central axis of the electromagnet.

[0008] Due to this arrangement, the electromagnet is arranged around a central axis. For example, the electromagnet can be annular around the central axis. However, the shape of the electromagnet is not limited to an annular shape and can have any shape with a center, such as a parallelogram, an ellipse, a polygon, etc. Thus, the air gap formed between the electromagnet and the slider can extend in a direction substantially parallel to the central axis. As a result, when the slider moves in the slider actuation direction, the distance between the slider and the electromagnet remains constant with respect to the direction perpendicular to the central axis. As a result, although the slider can move, the slider will never be adjacent to the electromagnet in the manner described above with reference to Figure 8 so that the noise associated with the slider being adjacent to the electromagnet can be avoided. Moreover, the electromagnetic brake can be configured such that the slider will not be adjacent to other structural members of the electromagnetic brake. Thus, an essentially silent electromagnetic brake can be obtained.

[0009] In one embodiment, the slider is arranged radially inside the electromagnet and the electromagnet is arranged radially outside the slider. Alternatively, the slider can be arranged radially outside the electromagnet and the electromagnet can be arranged radially inside the slider.

[0010] Preferably, the slider comprises a ferromagnetic material, such as iron. This allows the slider or a part of the slider to be used as part of the magnetic circuit of the electromagnet.

[0011] Preferably, the electromagnet and the slider are respectively annular. This allows for a simple configuration that is easy to manufacture.

[0012] Preferably, the electromagnet includes a coil wound around a central axis and adapted to generate a magnetic field upon excitation. Also preferably, the electromagnetic brake includes a magnetic field adaptation device for adapting the magnetic field so as to generate a magnetic force acting on the slider in the slider actuation direction.

[0013] The magnetic field adaptation device adapts the magnetic field in such a way that the slider moves relative to the electromagnet in a manner parallel to the electromagnet rather than moving the electromagnet.

[0014] Preferably, the magnetic field adaptation device includes at least one electromagnet protrusion extending from the electromagnet into the air gap and at least one slider protrusion extending from the slider into the air gap. The provision of the protrusions allows for a suitable structure to provide a magnetic field adaptation device that can be easily manufactured.

[0015] Preferably, in a state where the electromagnet is not actuated, the electromagnet protrusion and the slider protrusion are offset from each other in the slider actuation direction. Since the protrusions are offset from each other in the state where the electromagnet is not actuated, when a magnetic field is generated due to the actuation of the electromagnet, an electromagnetic force is generated between the protrusions, and these protrusions are offset from each other, so that the slider protrusion will be attracted by the electromagnet protrusion, where the magnetic force corresponds to the amount of current supplied to the electromagnet. As a result, the slider can move in the slider actuation direction.

[0016] Preferably, the electromagnet protrusion includes an inclined surface on the side facing along the slider actuation direction, and the slider protrusion includes an inclined surface on the side facing opposite to the slider actuation direction. The inclined surface is inclined with respect to the direction perpendicular to the slider actuation direction. The inclined surface improves the adaptability of the magnetic field in a certain way to more suitably generate the magnetic force that causes the protrusions to attract each other.

[0017] Preferably, a permanent magnet is arranged parallel to the electromagnet. The permanent magnet provides a permanent magnetic field, which combines with the magnetic field of the electromagnet when the electromagnet is actuated. The permanent magnet reduces the magnetization / actuation of the electromagnet required to move the slider. Therefore, the permanent magnet ensures a magnetic force sufficient to move the slider. As a result, the size of the coil of the electromagnet can be reduced, and thus the electromagnetic brake can be manufactured at a lower cost.

[0018] Preferably, the electromagnetic brake includes guiding means for guiding the slider in the slider actuation direction. The guiding means ensures that the slider moves along the slider actuation direction in such a way that the distance between the slider and the electromagnet in the direction perpendicular to the central axis is not reduced. As a result, it can be ensured that the slider never contacts the electromagnet at any position. This ensures the natural silence of the electromagnetic brake.

[0019] Preferably, the electromagnetic brake further includes at least one spring for pushing the slider in a direction opposite to the slider actuation direction. The at least one spring allows the slider to be brought into the brake-closed position or the brake-open position.

[0020] Preferably, the electromagnetic brake includes a friction member that is connected to the slider and is adapted to press against a braking surface. Preferably, the slider actuation direction is the direction in which the slider moves to press the friction member against the braking surface. This allows for a spring-loaded electromagnetic brake that closes when the electromagnet is not activated. Alternatively, the slider actuation direction is the direction in which the slider moves to move the friction member away from the braking surface. This allows for a spring-loaded electromagnetic brake that opens when the electromagnet is not activated.

[0021] Preferably, the electromagnetic brake is adapted to be applied to a transportation system, such as an elevator, an escalator or a moving walkway. Preferably, the electromagnetic brake is adapted to be applied to a traction machine, where the electromagnetic brake can be attached to the frame of the traction machine to brake the shaft and / or the traction wheel of the traction machine. However, the electromagnetic brake is not limited to these applications and can be applied to any technical field where an electromagnetic brake that is essentially silent is desired.

[0022] Preferably, the slider includes a plurality of blind holes, each for accommodating one of the plurality of springs.

[0023] Preferably, the slider includes a plate-shaped sliding portion, and the spring is disposed coaxially with respect to the electromagnet to push the plate-shaped sliding portion in a direction opposite to the slider actuation direction.

[0024] Preferably, at least two sets of electromagnets and sliders are provided. In this case, each electromagnet is arranged around its own central axis such that the electromagnetic brake includes as many central axes as the number of electromagnet and slider sets. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] These and other objects, features and advantages will become more apparent from the following detailed description of embodiments of the present invention in conjunction with the accompanying drawings, in which:

[0026] Figure 1 is a schematic cross-sectional view of an electromagnetic brake according to a first embodiment of the present invention.

[0027] Figure 2 shows the magnetic field when the coil is not energized.

[0028] Figure 3 shows the magnetic field when the coil is energized.

[0029] Figure 4 is a graph showing the relationship between the moving position of the slider and the forces of the spring and the electromagnet.

[0030] Figure 5 is a schematic cross-sectional view of an electromagnetic brake according to a second embodiment of the present invention.

[0031] Figure 6A is a schematic cross-sectional view of an electromagnetic brake according to a third embodiment of the present invention in a state where the brake is engaged.

[0032] Figure 6B is a schematic cross-sectional view of an electromagnetic brake according to a third embodiment of the present invention in a state where the brake is opened.

[0033] Figure 7 is a schematic cross-sectional view of an electromagnetic brake according to a fourth embodiment of the present invention.

[0034] Figure 8 is a schematic cross-sectional view of a conventional electromagnetic brake. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] First Embodiment

[0036] As Figure 1 shown, the electromagnetic brake 1 according to the first embodiment of the present invention includes an annular flange 2 made of steel such as S355, an annular coil 5 provided inside the flange 2, and a slider 3 provided on the radially inner side of the flange 2.

[0037] The flange 2 is mounted to a support 12, such as the housing of an electromagnetic brake 1, which can be mounted, for example, to a traction machine (not shown) of an elevator. The flange 2 is annular about a central axis SA.

[0038] The coil 5 is placed inside the flange 2 and is also annular about the central axis SA. The coil 5 includes a winding (not shown) which is oriented on a substantially circular path about the central axis SA. Since the coil 5 is a main component of the electromagnet, the electromagnet according to the invention is arranged about the central axis SA. In other words, the central axis is defined by the coil 5 and thus by the electromagnet.

[0039] The annular permanent magnet 8 is provided inside the flange 2 at a position between the coil 5 and the slider 3 and is thus parallel to the electromagnetic magnet 2.

[0040] In this embodiment, the flange 2 consists of an upper part 2a and a lower part 2b, between which the coil 5 and the permanent magnet 8 are arranged.

[0041] The slider 3 has an annular sliding part 3a and a plate-shaped sliding part 3b connected to the bottom of the annular flange part 3a. The slider 3 is substantially symmetric about the central axis SA.

[0042] The friction pad 10 is mounted to the bottom of the plate-shaped sliding part 3b. When the slider 3 moves downward in Figure 1 and thus towards the brake disc 11, the friction pad 10 can come into contact with the braking surface of the brake disc 11.

[0043] A plurality of springs 9 are provided between the support 12 and the slider 3 to push the slider 3 towards the brake disc 11. The springs 9 can be helical springs and can be distributed uniformly along the circumferential extension of the slider 3. Preferably, four springs 9 are provided, but the number is not limited to four.

[0044] Protrusions 7 are formed on the radially outer side of the annular sliding part 3a. Each protrusion 7 is annular and has a cross-sectional shape with an upper straight line perpendicular to the central axis SA, an outer straight line parallel to the central axis SA, and a lower straight line extending downwardly and obliquely towards the annular sliding part 3a. The lower straight line in the sectional view corresponds to the inclined surface 7a of the protrusion 7, which is inclined with respect to a direction perpendicular to the slider actuation direction. The upper straight line and the radially outer straight line correspond to the annular surface of the protrusion 7. In the first embodiment, the slider 3 includes ten protrusions 7.

[0045] Therefore, a recess 15 is formed between two adjacent protrusions 7. Since there are ten protrusions 7, the slider 3 includes nine recesses. The upper four recesses 15 and the lower four recesses 15 have the same depth in a direction perpendicular to the central axis SA. An intermediate recess 16 is formed between two protrusions 7 located in the middle of the slider 3 in a direction with respect to the central axis SA. In other words, when the protrusions 7 are numbered from the bottom side to the top side of the slider 3, the intermediate recess 16 is formed between the protrusions 7 numbered five and six, and it is deeper than the other recesses 15 with respect to the direction perpendicular to the central axis SA, and it is larger than the other recesses 15 in the direction of the central axis SA. In addition, the intermediate recess 16 is longer than the other recesses in the direction of the central axis SA.

[0046] Protrusions 6 are formed on the radially inner side of the flange 2. Each protrusion 6 is annular, and its cross-sectional shape has a lower straight line perpendicular to the central axis SA, an outer straight line parallel to the central axis SA, and an upper straight line extending obliquely upward toward the flange 2. The upper straight line in the sectional view corresponds to the inclined surface 6a of the protrusion 6, which is inclined with respect to the direction perpendicular to the slider actuation direction. The lower straight line and the radially inner straight line correspond to the annular surface of the protrusion 7. In the first embodiment, the flange 2 includes ten protrusions 6.

[0047] Therefore, a recess 13 is formed between two adjacent protrusions 6. Since there are ten protrusions 6, the flange 10 includes nine recesses. The upper four recesses 13 and the lower four recesses 13 have the same depth in a direction perpendicular to the central axis SA. An intermediate recess 14 is formed between two protrusions 6 located in the middle of the flange 2 in a direction with respect to the central axis SA. In other words, when the protrusions 6 are numbered from the bottom side to the top side of the flange 2, the intermediate recess 14 is formed between the protrusions 6 numbered five and six, and it is deeper than the other recesses 13 in the direction perpendicular to the central axis SA. In addition, the intermediate recess 14 is longer than the other recesses 13 in the direction of the central axis SA. The bottom of the intermediate recess 14 of the flange 2 is formed by the radially inner surface of the permanent magnet 8.

[0048] An air gap 4 is provided between the radially inner side of the flange 2 and the radially outer side of the slider 3. In Figure 1 the sectional view, this air gap extends substantially in a direction parallel to the central axis SA. In fact, the air gap 4 is defined by the surfaces of the protrusions 6 of the flange 2, the surfaces of the recesses 13, 14 between these protrusions 6, the surfaces of the protrusions 7, and the surfaces of the recesses 15, 16 between these protrusions 7. Therefore, the length of the air gap 4 in the direction perpendicular to the central axis SA is larger at a first portion perpendicular to the central axis SA passing through the recess 13 of the flange and the recess 15 of the slider 3 than at a second portion perpendicular to the central axis SA passing through the protrusion 6 of the flange 2 and the protrusion 7 of the slider 3.

[0049] Figure 2 Shows the magnetic field in the annular portions of the flange 2 and the slider 3 in the state where the coil 5 is not energized. In this state, the magnetic field is generated only by the permanent magnet 8, and the magnetic field propagates around the coil 5. Therefore, the magnetic flux density in the air gap region is so small that no magnetic force is generated that would overcome the spring force of the spring 9. As a result, the electromagnetic brake 1 is in the closed state, in which the electromagnetic brake 1 is pressed against the braking surface of the disc 11 by the spring force of the spring 9. In this closed position, the slider 3 is offset from the flange 2 towards the braking surface of the brake disc in the direction of the central axis SA, such that the projection 7 of the slider 3 is correspondingly offset from the projection 6 of the flange.

[0050] When the coil 5 is energized, the magnetic field of the permanent magnet 8 and the magnetic field of the energized coil 5 pass through the annular portion of the slider 3. As Figure 3 shown, in the region where the projections 6 and 7 are close to each other, the magnetic flux density is particularly high, where a part of the air gap 4 formed between the flange 2 and the slider 3 is narrow. The magnetic field generated in the projections 6 and 7 generates an attractive force between the flange 2 and the slider 3, which has a force component directed away from the brake disc 11 in the slider actuation direction. Since the slider 3 is guided by a guiding device to slide in the slider actuation direction, the slider 3 is prevented from moving in a direction perpendicular to the slider actuation direction. The guiding device can be, for example, a guiding rod on which the slider 3 is mounted by a sliding bearing.

[0051] Figure 4 Shows the spring force curve 20 and the magnetic force curves 21 to 24, which represent the relationship between the respective forces (vertical axis) of the slider 3 and the associated movement positions (horizontal axis). The movement position -2.00 mm corresponds to the position where the slider 3 is offset from the flange 2 by the maximum amount such that the projections do not overlap each other at all. In the present embodiment, the brake is closed at the movement position -1.25 mm. The movement position 0.00 mm corresponds to the position where the brake 1 is fully open, i.e., the projection 6 of the slider 3 is aligned with the projection 7 of the flange 2. In this position, the slider 3 has been displaced from the brake disc 11 in the slider actuation direction to the maximum amount.

[0052] The spring force curve 20 is substantially linear. The magnetic force curves 21 to 24 are non-linear because the magnetic force is exponentially proportional to the air gap length in the magnetic circuit. When the position of the slider changes, the air gap length in the magnetic circuit changes, resulting in a reduction in the offset between the projections 6, 7 such that the projections 6, 7 are aligned with each other to a greater extent.

[0053] The magnetic force curve 21 shows the state where no current is supplied to the coil 5. In this state, the current density ( Figure 4 "Virrantiheys" in Finnish) is zero, and the magnetic force generated is substantially zero.

[0054] The magnetic force curve 22 shows the state of the coil 5 excited with a current density of 5000000 A / m 2 . The magnetic force curve 22 intersects the spring force curve 20 at the position of -1.125 mm. At this position, the protrusions 6 and 7 are more aligned compared to the state where the coil 5 is not excited and the slider 3 is positioned at -2.00 mm. Therefore, the air gap 4 becomes smaller.

[0055] The magnetic force curve 23 shows the state of the coil 5 excited with a current density of 5000000 A / m 2 . The magnetic force curve 23 intersects the spring force curve 20 at the position of -0.8 mm. At this position, the protrusions 6 and 7 are more aligned compared to the state where the coil 5 is excited with a current density of 5000000 A / m 2 and the slider 3 is positioned at -1.125 mm. Therefore, the air gap 4 becomes even smaller.

[0056] The magnetic force curve 24 shows the state of the coil 5 excited with a current density of 15000000 A / m 2 . The magnetic force curve 24 intersects the spring force curve 20 at the position of -0.75 mm. At this position, the protrusions 6 and 7 are more aligned compared to the state where the coil 5 is excited with a current density of 10000000 A / m 2 and the slider 3 is positioned at -0.8 mm. Therefore, the air gap 4 becomes even smaller.

[0057] Therefore, it can be understood that the position of the slider 3 will be at the intersection point of the electromagnetic force corresponding to the applied current density and the spring force, and by controlling the current density, that is, the current supplied to the coil 5, the slider 3 will move. During the movement of the slider 3, the protrusions 6 and 7 are more and more aligned with each other. As described above, the air gap 4 is respectively formed between the protrusions 6 and 7 and the recesses 13, 14, 15, 16. In the region where the recesses 13, 14, 15, 16 face each other, the air gap is larger than that in the region where the protrusions 6 and 7 face each other. Therefore, when the slider 3 moves in the slider actuation direction, the ratio of the protrusions 6 and 7 facing each other becomes larger relative to the ratio of the recesses 13, 14, 15, 16 facing each other. As a result, when the slider 3 moves in the sliding direction to open the brake 1, the air gap 4 becomes smaller.

[0058] Second Embodiment

[0059] Figure 5Figure 101 shows an electromagnetic brake according to a second embodiment of the present invention. The components of this electromagnetic brake have been denoted by reference numerals, which are obtained by adding 100 to the reference symbols used in the first embodiment. Hereinafter, only the main differences from the first embodiment will be described.

[0060] In the second embodiment, a sliding member 103 is provided on the radially outer side of the flange 102 and includes a blind hole 117 for accommodating a spring 109. Although only two blind holes 117 are shown in Figure 5 , a plurality of blind holes 117 and a corresponding number of springs 109 may be provided on the circumferential extension of the sliding member 103. Preferably, four blind holes 117 and four springs 109 are uniformly distributed on the circumferential extension.

[0061] In addition, in this embodiment, the flange 102 is formed by an upper part 102a and a lower part 102b, and a coil 105 and a permanent magnet 108 are provided between the upper part 102a and the lower part 102b. In this embodiment, the upper part 102a is integrally formed with the support member 112.

[0062] Moreover, the distribution of the protrusions 106, 107 is different from the distribution of the protrusions 6, 7 in the first embodiment. In this embodiment, seven protrusions 106 having an inclined surface 106a are formed in the lower part 102b of the flange 102, and one protrusion 106 having an inclined surface 106a is formed in the upper part 102a. A corresponding number of protrusions 107 are formed in the sliding member 103 below and above the recess 116, respectively. Except for this, the operation mode is basically the same as that of the first embodiment.

[0063] Third Embodiment

[0064] Figure 6A and 6B Figure 201 shows an electromagnetic brake according to a third embodiment of the present invention. The components of this electromagnetic brake have been denoted by reference numerals, which are obtained by adding 200 to the reference symbols used in the first embodiment. Hereinafter, only the main differences from the first embodiment will be described.

[0065] Compared with the first embodiment, the electromagnetic brake 201 according to this embodiment has a more compact structure. Although the plate-shaped sliding part 3b according to the first embodiment has a central hole, the plate-shaped sliding part 203b according to the third embodiment does not have such a hole but is formed as a continuous plate.

[0066] In addition, the electromagnetic brake 201 according to this embodiment includes only a single spring 209, which is disposed between the support member 212 and the plate-shaped sliding portion 203b and is configured to push the slider 203 away from the support member 212, i.e., in a direction opposite to the slider actuation direction. The single spring 209 is arranged to be substantially coaxial with the annular sliding portion 203a. In other words, the central axis of the spring 209 corresponds to the central axes of the slider and the electromagnet.

[0067] In addition, the electromagnetic brake 201 according to this embodiment is configured to apply a braking force to the outer peripheral surface of the traction wheel of the traction machine. Therefore, the friction pad 210 has a curved surface on the side facing away from the plate-shaped sliding portion 203b, and the curvature of the curved surface corresponds to the curvature of the outer peripheral surface of the traction wheel of the traction machine.

[0068] Fourth Embodiment

[0069] Figure 7 An electromagnetic brake 301 according to a third embodiment of the present invention is shown. The components of the electromagnetic brake have been denoted by reference numerals, which are obtained by adding 300 to the reference numerals used in the first embodiment. Hereinafter, only the main differences with respect to the third embodiment will be described.

[0070] The electromagnetic brake 301 according to this embodiment includes two sets of flanges 302 and sliders 303 each having the structure of the third embodiment. In addition, as in the third embodiment, each slider 303 is pushed by a single spring 312. Except for the curved surface of the friction pad 210 in the third embodiment, each friction pad 310 of the fourth embodiment has a flat surface on the side facing away from the plate-shaped sliding portion 303b because the electromagnetic brake 301 is applied to a brake disc 311.

[0071] With the electromagnetic brake according to the embodiment, the slider can move while overcoming the spring force of the spring, and the air gap is always maintained between the slider and the flange. Therefore, since the slider never abuts against the flange, no noise is generated as in Figure 8 the conventional electromagnetic brake shown, which is generated by the abutment between the flange and the armature. Therefore, the electromagnetic brake according to the embodiment is essentially silent.

[0072] Since the slider moves in proportion to the current density of the coil, the dropping / closing of the electromagnetic brake is also essentially silent. Referring to Figure 4 , the slider position can be set by assuming the intersection point of the magnetic force curve and the spring force curve without friction loss and considering that the mass of the slider can be ignored. Therefore, by correspondingly reducing the current of the coil, the brake can be closed silently.

[0073] In addition, in the embodiment, there is also an air gap between the upper part of the sliding member and the support member. When the electromagnetic brake is operated, the air gap above the sliding member changes in the direction of the central axis, which can be better understood from Figure 6A and 6B . However, the size of the air gap can be set such that when the electromagnetic brake is operated (see, for example, Figure 6B ), the sliding member does not abut against the support member. Also for this reason, the electromagnetic brake according to the embodiment is essentially silent.

[0074] In addition, the structure of the electromagnetic brake according to the embodiment is simpler, so less maintenance is required.

[0075] The present invention is not limited to the above embodiments and can be modified as follows.

[0076] The electromagnetic brake according to the embodiment has a configuration in which the sliding member is pushed by a spring against the brake disc into the closed position. However, the present invention can be applied to an electromagnetic brake in which the sliding member is pushed away from the brake disc by a spring to the open position and the electromagnet is configured to move the sliding member in the direction of actuation of the sliding member towards the brake disc against the spring force when the electromagnet is actuated.

[0077] The electromagnetic brake according to the embodiment has a permanent magnet provided between the coil and the sliding member. The permanent magnet ensures the opening force of the electromagnet and allows the size of the coil to be reduced. However, the permanent magnet can be omitted, for example, in applications where a large braking force is not required, so that the spring force is smaller and thus the magnetic force required to open the brake is smaller. Alternatively, in the case of omitting the permanent magnet, the coil can be made larger.

[0078] In the first, second, and fourth embodiments, the present invention is applied to a brake disc. However, the present invention can be applied to other types of brakes that require moving a friction pad to provide a braking action, such as the brake of the third embodiment. Therefore, the configurations of the first, second, and fourth embodiments can be applied to a brake in which a curved friction pad is applied to the periphery of a rope disc, and the configuration of the third embodiment can be applied to a brake disc.

[0079] In the embodiment, the inclined surfaces of the electromagnet protrusion and the sliding member protrusion are straight surfaces. However, these surfaces can alternatively be curved surfaces.

Claims

1. An electromagnetic brake (1), comprising: An electromagnet (2) arranged around a central axis (SA); A slider (3) capable of moving relative to the electromagnet (2) in a slider actuation direction when the electromagnet (2) is actuated; and An air gap (4) provided between the electromagnet (2) and the slider (3), through which a magnetic field passes when the electromagnet (2) is actuated, wherein The slider (3) is arranged radially inside or outside the electromagnet (2) relative to the central axis (SA), and the central axis is parallel to the slider actuation direction, The air gap extends in a direction parallel to the central axis, and when the slider moves in the slider actuation direction, the distance between the slider and the electromagnet remains constant relative to a direction perpendicular to the central axis.

2. The electromagnetic brake (1) according to claim 1, wherein, The electromagnet (2) and the slider (3) are each annular.

3. The electromagnetic brake (1) according to claim 1 or 2, wherein, The electromagnet (2) includes a coil (5) wound around the central axis (SA) and adapted to generate a magnetic field when excited, and further includes: Magnetic field adaptation means (6, 7) for adapting the magnetic field to generate a magnetic force acting on the slider (3) in the slider actuation direction.

4. The electromagnetic brake (1) according to any one of claims 1 to 3, wherein, The magnetic field adaptation means (6, 7) includes: At least one electromagnet protrusion (6) extending from the electromagnet (2) into the air gap (4), and At least one slider protrusion (7) extending from the slider (3) into the air gap (4), wherein In a state where the electromagnet (2) is not actuated, the electromagnet protrusion (6) and the slider protrusion (7) are offset from each other in the slider actuation direction.

5. The electromagnetic brake (1) according to claim 4, wherein, The electromagnet protrusion (6) includes an inclined surface (6a) on a side facing in the slider actuation direction, and The slider protrusion (7) includes an inclined surface (7a) on a side facing opposite to the slider actuation direction, wherein The inclined surfaces (6a, 7a) are inclined relative to a direction perpendicular to the slider actuation direction.

6. The electromagnetic brake (1) according to any one of the foregoing claims, further comprising: A permanent magnet (8) arranged parallel to the electromagnet (2).

7. The electromagnetic brake (1) according to any one of the foregoing claims, further comprising: Guiding means for guiding the slider (3) in the slider actuation direction.

8. The electromagnetic brake (1) according to any one of the foregoing claims, further comprising: At least one spring (9) for pushing the slider (3) in a direction opposite to the slider actuation direction.

9. The electromagnetic brake (1) according to any one of the foregoing claims, further comprising: A friction member (10) connected to the slider (3) and adapted to press against a braking surface (11), The slider actuation direction is the direction in which the slider (3) moves to press the friction member (10) against the braking surface (11), or The slider actuation direction is the direction in which the slider (3) moves to move the friction member (10) away from the braking surface (11).

10. The electromagnetic brake (1) according to any one of the foregoing claims, wherein, The electromagnetic brake (1) is adapted to be applied to a transportation system, such as an elevator, an escalator or a moving walkway.

11. The electromagnetic brake (1) according to any one of the foregoing claims, wherein,The electromagnetic brake (1) is adapted to be applied to a traction machine.

12. The electromagnetic brake (101) according to any one of claims 8 to 11, wherein, The slider (103) includes a plurality of blind holes (117), each for receiving one of a plurality of springs (109).

13. The electromagnetic brake (201) according to any one of claims 8 to 11, wherein, The slider (203) includes a plate-like sliding portion (203b), and the spring (209) is arranged coaxially with respect to the electromagnet (202) to push the slider (203) in a direction opposite to the slider actuation direction.

14. The electromagnetic brake (301) according to any one of the preceding claims, wherein, At least two sets of electromagnets and sliders are provided.

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