Electromagnetic coupling device

Abstract

To provide an electromagnetic coupling device that can reduce the effort required for installation at a delivery destination.SOLUTION: An electromagnetic coupling device comprises an attracting body 2 and an attractable body 3. The attracting body 2 comprises a yoke 21 and a coil 22. The attractable body 3 comprises: a hub 31 that is fixed circumferentially and movably engaged in an axial direction, to a rotating shaft S which is an installation object; an armature 32 that is integral with the hub 31 and comes into contact with the yoke 21 by magnetic force when energization to the coil 22, thereby stopping circumferential relative rotation with respect to the yoke 21; a gap retaining member 33 that is located between the hub 31 and the armature 32 and is fixed to the rotating shaft S; and a biasing portion 34 that is arranged on the opposite side to the gap retaining member 33 relative to the armature 32. Fixing force of the gap retaining member to the rotating shaft S is smaller than attractive force between the yoke 21 and the armature 32 by the magnetic force of the coil 22 and is greater than the biasing force of the biasing portion 34.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electromagnetic coupling device that can automatically adjust the gap between a yoke and an armature. [Background technology]

[0002] An example of such an electromagnetic coupling device (specifically, an electromagnetic brake or electromagnetic clutch) is described in Patent Document 1. This electromagnetic coupling device is configured by combining a friction plate that is integral with a yoke equipped with a coil, and a disk-shaped armature that is disposed opposite the friction plate and rotates integrally with the rotating shaft. With this configuration, when the coil is energized, the magnetic force attracts the armature, thereby braking in the case of an electromagnetic brake.

[0003] As the armature wears, its axial dimension decreases (its thickness decreases). This increases the gap (gap) between the friction plate and the armature when not excited. The electromagnetic coupling device described in Patent Document 1 is provided with a coupling member to automatically adjust and stabilize the gap. This coupling member is a rod-shaped member that is capable of moving axially while generating friction. When the armature is attracted to the friction plate by magnetic force, it moves by the amount of wear of the armature, thereby maintaining a constant gap between the friction plate and the armature.

[0004] However, with this configuration, when the destination of the electromagnetic coupling device attaches a rotating shaft owned by the destination to the hub that fixes the armature, it is necessary to fix the hub and rotating shaft in the axial direction using a retaining ring or the like, which makes installation work at the destination time-consuming. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 1-22493 Summary of the Invention [Problem to be solved by the invention]

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an electromagnetic coupling device that can reduce the labor required for installation at the delivery site. [Means for solving the problem]

[0007] The present invention provides an electromagnetic coupling device comprising an attractor and an attractable body arranged alongside the attractor in the axial direction and rotatable circumferentially relative to the attractor, wherein the attractor comprises a yoke and a coil provided on the yoke, and the attractable body comprises a hub fixed circumferentially to a rotating shaft on which the electromagnetic coupling device is to be installed and movably engaged in the axial direction, an armature that is integral with the hub and comes into contact with the yoke due to magnetic force when the coil is energized, thereby stopping circumferential rotation relative to the yoke, a gap retaining member that is located between the hub and the armature and fixed to the rotating shaft, and a biasing portion that is arranged on the opposite side of the gap retaining member from the armature and generates an axial biasing force, wherein the fixing force of the gap retaining member to the rotating shaft is smaller than the attractive force between the yoke and the armature caused by the magnetic force of the coil and larger than the biasing force of the biasing portion.

[0008] With this configuration, the hub only needs to be attached to the rotating shaft in a state where it can move in the axial direction at the delivery site, which eliminates the need to fix the hub and the rotating shaft so that they are immovable in the axial direction.

[0009] The present invention may further include a spacer provided between the armature and the gap retaining member.

[0010] According to this configuration, by using the spacer, the distance in the axial direction can be adjusted to match the biasing force of the biasing portion.

[0011] In the present invention, the back surface of the armature that faces the yoke may be an abutment surface that abuts against the tip surface of the rotary shaft.

[0012] This configuration makes it easy to align the rotating shaft with the electromagnetic coupling device when installing the rotating shaft. [Effects of the Invention]

[0013] The present invention eliminates the need to fix the hub and the rotating shaft so that they are immovable in the axial direction, thereby providing an electromagnetic coupling device that reduces the labor required for installation at the delivery site. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a cross-sectional view taken along an axial direction of an electromagnetic brake according to an embodiment of the present invention. [Figure 2] 1, showing the operation of the electromagnetic brake in a non-excited state. [Figure 3] 1, showing the operation of the electromagnetic brake in an excited state. FIG. [Figure 4] 1 and shows the operation of the electromagnetic brake in a non-excited state (before the gap retention ring moves) when the armature is worn. [Figure 5] 1 and shows the operation of the electromagnetic brake, illustrating the excited state when the armature is worn (while the armature is moving, before the gap retention ring is moved). [Figure 6] 1 and shows the operation of the electromagnetic brake, illustrating the excited state when the armature is worn (the state in which the armature is in contact with the yoke, after the gap retention ring has moved). FIG. [Figure 7] 1 and shows the operation of the electromagnetic brake in a non-excited state (after the gap retention ring has moved) when the armature has worn. [Figure 8]1 shows another embodiment (part 1) of the electromagnetic brake. [Figure 9] 2 shows another embodiment (part 2) of the electromagnetic brake. [Figure 10] 10 shows another embodiment (part 3) of the electromagnetic brake. DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention will be described below by taking up one embodiment and by referring to the drawings.

[0016] An electromagnetic coupling device is a device configured to transmit or block power from the primary side to the secondary side by moving a primary side component toward or away from a secondary side component, and specific application examples include an electromagnetic brake or an electromagnetic clutch. When the primary side, which is the driving side, rotates around an axis, an electromagnetic brake is configured to fix the secondary side (braking side) so that it does not rotate, and an electromagnetic clutch is configured so that the secondary side (driven side) rotates around the same axis as the primary side. Below, an electromagnetic brake 1 shown in FIG. 1 etc. will be described as one embodiment of the present invention.

[0017] As shown in FIG. 1 , the electromagnetic brake 1 of this embodiment includes an attractor 2 that generates a magnetic force, which is an attractive force, and an attractable object 3 that is arranged axially alongside the attractor 2 and is rotatable circumferentially relative to the attractor 2. The attractor 2 and attractable object 3 are arranged inside a case 4. In this embodiment, the case 4 is formed into a cylindrical shape with an internal step. A bearing 5 (a ball bearing in this embodiment) is fixed to the case 4 and supports a rotating shaft S (not included in the present invention) that belongs to the facility at the destination where the electromagnetic brake 1 is delivered. Note that although the rotating shaft S is shown short in the figure, the length of the rotating shaft S is not particularly limited. The portion of the rotating shaft S to which the bearing 5 is attached is not a spline shaft, as described below, but rather a shaft with a circular cross section. To prevent axial displacement of the rotating shaft S relative to the bearing 5, a stopper 6 is attached to the rotating shaft S adjacent to the bearing 5 on the side farther from the attractor 2 and attractable object 3 (the left side in the figure). The stopper 6 can be, for example, an E-shaped retaining ring. On the other hand, the bearing 5 on the side closer to the attractor 2 and the attractable object 3 (the right side in the figure) has its inner ring abutting against a stepped portion S1, which is a large-diameter portion formed on the rotating shaft S, thereby fixing its axial position. Note that a stopper 6 may be fixed to the rotating shaft S in advance instead of the stepped portion S1. After the rotating shaft S is attached to the case 4 and the bearing 5, the attractable object 3 is attached as described below. Thereafter, the attractor 2 is fixed in the axial direction with a ring-shaped stopper 7, and a lid 8 is attached to the case 4 on the side opposite the rotating shaft S, thereby closing the opposite end of the case 4. The electromagnetic brake 1 of this embodiment formed in this way is configured as a single unit incorporating the attractor 2 and the attractable object 3.

[0018] This electromagnetic brake 1 is attached to the tip of a rotating shaft S owned by the customer, for example, at the customer's location. First, the rotating shaft S is inserted from right to left in the figure into the case 4 (without the attractor 2 or attractee 3 attached) to which the bearings 5 ​​are attached. This insertion is performed so that the stepped portion S1 abuts against the inner ring of the right-side bearing 5 in the figure. Then, the stopper 6 is attached to the rotating shaft to the left of the left-side bearing 5 in the figure. The specific attachment method is not particularly limited as long as the relationship with the hub 31 described below is satisfied. The attractor 2 is directly attached to the rotating shaft S, and the attractor 2 is installed at a position facing the tip surface of the rotating shaft S, a predetermined distance away from the attractor 3. The attractor 2 includes a coil 22 that generates a magnetic force. Electrical wiring belonging to the customer's facility is connected to energize the coil 22.

[0019] The attracting body 2 includes a yoke 21 and a coil 22 fixed to the yoke 21. The attracting body 2 corresponds to the secondary side and is a part that is immovably fixed in the facility where the attracting body 2 is delivered. The yoke 21 and the coil 22 have the same configuration as those incorporated in conventional electromagnetic brakes. That is, the yoke 21 is made of a magnetic material, and the coil 22 is formed of a winding wound around the yoke 21. The attracting body 2 has a rotationally symmetric shape with respect to an extension of the central axis of the rotating shaft S. A through hole 211 with a circular cross section is provided at the radial center of the yoke 21. This through hole 211 is provided mainly to form a magnetic path. Furthermore, during maintenance, etc., a tool can be inserted into the through hole 211 from the side facing the tip of the rotating shaft S. In this regard, the diameter of the through hole 211 can be formed larger than the diameter of a through hole 321 (described below) formed in the armature 32 (although in this embodiment, the diameters are the same). By doing this, by inserting a rod-shaped tool and pressing the surface of the armature 32 facing the through-hole 211, it is possible to check the movement of the spring, malfunctions due to galling between parts, and adhesion of the friction surfaces. It is also possible to know the condition of the electromagnetic brake 1 by checking the dimensions (measuring the dimensions to the tip surfaces of the armature 32 and the rotating shaft S). For example, by subtracting the axial dimension of the yoke 21 from each measurement value during installation, it is possible to confirm that the electromagnetic brake 1 is installed in the position assumed in the design. The condition can also be checked during inspection. The axial dimension of the yoke 21 may be measured with the armature 32 held in suction.

[0020] The attractable body 3 includes a portion that is attracted by the magnetic force of the attracting body 2, and includes as its main components a hub 31, an armature 32, a gap retaining ring 33 as a gap retaining member, a biasing portion 34, and a spacer 35. The attractable body 3 corresponds to the primary side configuration, and is provided so as to rotate together with the rotation shaft S around the central axis of the rotation shaft S.

[0021] The hub 31 has a substantially cylindrical shape. As shown in FIG. 2 , the hub 31 is integrally formed with an inner diameter portion 311 extending perpendicular to the axial direction on the radially inner side, an outer diameter portion 312 that is closer to the armature 32 than the inner diameter portion 311 and extends perpendicular to the axial direction on the radially outer side, and a connecting portion 313 that is continuous with the inner diameter portion 311 and the outer diameter portion 312 and extends along the axial direction. The hub 31 is fixed in the circumferential direction to the rotating shaft S on which the electromagnetic brake 1 is installed and engages movably in the axial direction. For this reason, the rotating shaft S is a splined shaft with splines (teeth) formed on its outer periphery at least within the range in which the hub 31 moves. The inner diameter end of the inner diameter portion 311 of the hub 31 engages with this splined shaft. For this reason, although not shown, the inner peripheral edge of the inner diameter portion 311 has a concave-convex shape that matches the splined shaft.

[0022] The armature 32 is an integral part of the hub 31. In this embodiment, the armature 32 is attached to the radially outer portion 312 of the hub 31 by a plurality of screws 36 arranged at equal intervals around the circumference and threaded in the axial direction. The armature 32 is made of a magnetic material. When the coil 22 is energized, the armature 32 contacts (abuts) the yoke 21 due to magnetic force. This friction stops the armature 32 from rotating relative to the yoke 21 in the circumferential direction. Due to this friction, the tip side of the armature 32 relative to the rotation axis S wears over time. A through-hole 321 with a circular cross section is provided at the radial center of the armature 32 to allow insertion of a tool from the side facing the tip of the rotation axis S during maintenance, etc. The cross-sectional shape of the through-hole 321 may be polygonal rather than circular. It may be shaped to fit a hexagonal wrench, for example, primarily for maintenance purposes. Furthermore, by inserting a "bamboo-copter"-shaped object into the through-hole 321 and observing the "wings," it is easy to check whether the armature 32 is rotating or stopping. It can also be used when you want to rotate the rotation shaft S manually. In particular, when using the through-hole 321 in this way, the diameter of the through-hole 211 in the yoke 21 must be larger than the diameter of the through-hole 321. For these purposes, a through-hole (not shown) can also be provided in the lid 8.

[0023] The gap retaining ring 33 is a ring-shaped member sandwiched between the hub 31 and the armature 32 and fixed to the rotating shaft S. The material of the gap retaining ring 33 is not particularly important as long as it can stably generate the fixing force to the rotating shaft S described below. Preferable properties of the gap retaining ring 33 include non-magnetic properties and brittleness. A material with high resistance to wear (cutting) is also preferable. For example, when made from a resin material, using engineering plastics or super engineering plastics (e.g., PBT resin) can provide sliding properties and heat resistance and requires little manufacturing effort. In some cases, the gap retaining ring 33 may be made by cutting a metal (e.g., aluminum alloy).

[0024] The biasing portion 34 is disposed on the opposite side of the gap retaining ring 33 from the armature 32, and is a portion that generates a biasing force in the axial direction. In order to reduce the axial dimension, in this embodiment, a wave spring configured by winding a plate-shaped spring element such as a metal plate is used, but other types of springs such as a coil spring can also be used.

[0025] The spacer 35 is a ring-shaped member disposed between the armature 32 and the gap retaining ring 33. In this embodiment, the spacer 35 is made of an aluminum alloy; however, various non-magnetic materials may be used. By using the spacer 35, the axial distance can be adjusted to match the biasing force of the biasing portion 34. Furthermore, when the rotating shaft S is press-fitted into the attractable body 3, the spacer 35 can be held so that the gap retaining ring 33 does not move toward the armature 32. Similar to the gap retaining ring 33, desirable properties of the spacer 35 include non-magnetic properties, non-brittleness, and high resistance to wear (cutting). Furthermore, a slippery material is preferable. For example, when the spacer 35 is made of a resin material, engineering plastics and super engineering plastics (e.g., POMT resin) can be used. In some cases, the spacer 35 may be manufactured by cutting a metal (e.g., aluminum alloy).

[0026] The above-mentioned components are arranged in the axial direction, starting from the side closest to the attractor 2, along the outer periphery of the rotating shaft S, in the following order: armature 32, spacer 35, gap retention ring 33, biasing portion 34, and hub 31 (diametrical inner portion 311). A through-hole through which the rotating shaft S can pass is provided at the radial center of each of the spacer 35, gap retention ring 33, biasing portion 34, and hub 31. In particular, the diameter and shape of the through-hole of the gap retention ring 33 are set so that the rotating shaft S can be press-fitted as described below and so that the following fixing force is generated with respect to the rotating shaft S. Furthermore, the back surface of the armature 32 facing the yoke 21 (the surface on the left in each drawing) is flat, and this flat surface serves as the abutment surface with which the tip surface of the rotating shaft S (the end surface on the right in each drawing) abuts. Therefore, when combining the rotating shaft S, to which the case 4 equipped with the bearing 5 is attached as described above, with the attractable body 3, it is sufficient to circumferentially align the inner diameter portion 311 of the hub 31 with the spline axis of the rotating shaft S, and then press the rotating shaft S into the attractable body 3 until the tip end surface of the rotating shaft S abuts against the flat surface. This eliminates the need to fix the hub 31 and the rotating shaft S so that they are immobile in the axial direction. Furthermore, axial alignment when installing the rotating shaft S is easy. Since the rotating shaft S is pressed relative to the state in which the spacer 35 and the gap retaining ring 33 are positioned in front of the armature 32, the rotating shaft S is press-fit into the gap retaining ring 33, which is held in a fixed position.

[0027] Here, the fixing force of the gap retaining ring 33 to the rotation axis S (the portion thereof that is the spline shaft) is set to be smaller than the attractive force between the yoke 21 and the armature 32 due to the magnetic force of the coil 22, and larger than the biasing force of the biasing portion 34. Therefore, when the coil 22 is excited and the armature 32 moves axially relative to the yoke 21, the gap retaining ring 33 can move relative to the rotation axis S. On the other hand, the gap retaining ring 33 does not move relative to the rotation axis S due to expansion and contraction of the biasing portion 34 accompanying the axial movement of the hub 31 relative to the rotation axis S.

[0028] Next, we will explain step by step how the gap between the yoke 21 and the armature 32 is automatically adjusted. Figures 2 and 3 correspond to the initial state in which the armature 32 is not yet worn. Figures 4 to 7 correspond to the state after the armature 32 has become thinner due to wear.

[0029] 2 shows a non-excited state of the attracting body 2. In this state, the armature 32 is spaced apart from the yoke 21 in the axial direction, creating a gap.

[0030] The state shown in FIG. 3 shows the magnetized state of the attracting body 2. At this time, the armature 32 is attracted to the yoke 21 and tightly adheres to it. At this time, the rotating shaft S itself is immobile in the axial direction, and the hub 31 and armature 32 move (advance) relative to the yoke 21 along the spline axis of the rotating shaft S. This movement occurs regardless of the rotation of the rotating shaft S. Note that, because the gap retaining ring 33 and the spacer 35 do not move axially relative to the rotating shaft S, they are pressed by the inner diameter portion 311 of the hub 31, which moves axially, compressing the biasing portion 34 and making it approximately flat. However, because the fixing force of the gap retaining ring 33 to the rotating shaft S is set to be greater than the biasing force of the biasing portion 34, the gap retaining ring 33 does not move axially due to the compression of the biasing portion 34.

[0031] The state shown in Figure 4 shows the non-excited state of the attraction body 2 when the armature 32 is worn. In this state, as in Figure 2, the armature 32 is separated from the yoke 21 in the axial direction, creating a gap. For ease of explanation, Figure 4 exaggerates the widened state before the gap is automatically adjusted, and the actual gap does not differ so drastically.

[0032] FIG. 5 shows the magnetized state of the attracting body 2 when the armature 32 is worn, immediately after the armature 32 begins to move (advance) toward the yoke 21. At this time, as in FIG. 3, the biasing portion 34 is compressed by being pressed by the radially inner portion 311 of the hub 31, which is moving axially. However, because the armature 32 is thinner than in the state shown in FIG. 3, the armature 32 is still separated from the yoke 21 at this point, creating a gap. The adhesive force of the gap retaining ring 33 to the rotation axis S is set to be smaller than the magnetic attraction between the yoke 21 and the armature 32. Therefore, as shown in FIG. 6, the gap retaining ring 33 and the spacer 35 move toward the yoke 21 (in the direction of the arrow in FIG. 6) relative to the rotation axis S. The movement distance is equal to the worn thickness of the armature 32. As a result, the axial dimension of the gap becomes equal to the initial state (before wear).

[0033] The state shown in Fig. 7 shows the non-excited state of the attraction body 2 when the armature 32 has worn, after passing through the state shown in Fig. 6. At this time, the armature 32 is separated from the yoke 21, and a gap exists, but the axial distance of the gap is equal to the distance of the gap between the armature 32 and the yoke 21 in the state shown in Fig. 2.

[0034] As explained in the above order, in the electromagnetic brake 1 of this embodiment, the gap between the yoke 21 and the armature 32 is automatically adjusted.

[0035] As described above, with the electromagnetic brake 1 of this embodiment, there is no need to fix the hub 31 and the rotating shaft S so that they are immovable in the axial direction, which reduces the labor required for installation at the delivery site. However, it is possible to attach additional fixing brackets or the like after attaching the rotating shaft S to the hub 31. After installation, the gap between the yoke 21 and the armature 32 is automatically adjusted in accordance with wear of the armature 32, which also reduces the labor required for maintenance.

[0036] Up to this point, one embodiment of the present invention has been described, but the present invention is not limited to the above embodiment, and various modifications are possible within the scope of the gist of the present invention.

[0037] The above embodiment is an electromagnetic brake 1, but as mentioned above, the present invention can also be applied to an electromagnetic clutch.

[0038] In addition, the gap retaining member (gap retaining ring 33) and the spacer 35 are ring-shaped (O-shaped) members in the above embodiment, but are not limited to this and may be, for example, C-shaped members.

[0039] Alternatively, the armature 32 and the spacer 35 may be formed integrally. In this case, a groove such as an annular groove may be formed in the end of the armature 32 opposite the yoke 21, and a portion of the spacer 35 may be embedded therein to form an integral structure. In this way, when the armature 32 wears, the spacer 35 advances and is positioned closer to the armature 32 than the tip of the rotation shaft S, which can cause the spacer 35 to become displaced radially or tilted inside the case 4, thereby preventing subsequent interference with the movement of the hub 31 and the armature 32.

[0040] Alternatively, as shown in FIGS. 8 to 10, the armature 32 may be configured to have multiple through-holes extending in the thickness direction and circumferentially provided, and pins inserted into these through-holes. FIG. 8 shows an example in which a through-hole 322 is provided at the same radial position as the spacer 35. In this example, by protruding a pin 323 from the armature 32 toward the spacer 35 as shown, a preload can be applied to the biasing portion 34, thereby adjusting the biasing force of the biasing portion 34. This allows, for example, variations in the biasing force inherent to the biasing portion 34 to be accommodated. FIG. 9 shows an example in which a through-hole 321 (similar to the through-hole shown in FIG. 1) is provided at the radial center and utilized. The through-hole 321 axially communicates with the through-hole 211 of the yoke 21. In this example, by protruding a pin 324 from the armature 32 toward the rotation axis S as shown, the mounting position of the rotation axis S relative to the hub 31 can be adjusted axially. This allows for, for example, dimensional differences (due to manufacturing errors, etc.) in the axial direction of the hub 31 to be accommodated.

[0041] 10 shows an example in which a through hole 321 (similar to the through hole shown in FIG. 1, etc.) is provided at the radial center position of the armature 32, and further a bottomed recess S2 extending in the axial direction is provided at the tip at the radial center of the rotation shaft S. In this example, as shown in the figure, a pin 325 is made to protrude from the armature 32 in the direction toward the rotation shaft S, so that the tip of the pin 325 is inserted into the recess S2 (indicated by the arrow in the figure), and the armature 32 is directly integrated with the rotation shaft S, thereby suppressing, for example, vibration of the armature 32 during rotation. [Explanation of symbols]

[0042] 1 Electromagnetic coupling device, electromagnetic brake 2. Adsorbent 21 York 22 coils 3 Adsorbed object 31 Hub 32 Armature 33 Gap retaining member, gap retaining ring 34 energizing section 35 spacer 4 cases S rotation axis

Claims

1. An electromagnetic coupling device comprising an attractor and an attractable body arranged alongside the attractor in an axial direction and rotatable relative to the attractor in a circumferential direction, the adsorption body includes a yoke and a coil provided on the yoke, The adsorbate is a hub that is fixed in a circumferential direction to a rotating shaft on which the electromagnetic coupling device is to be installed and that engages with the rotating shaft so as to be movable in an axial direction; an armature that is integral with the hub and that comes into contact with the yoke due to magnetic force when the coil is energized, thereby stopping relative rotation in the circumferential direction with respect to the yoke; a gap retaining member located between the hub and the armature and fixed to the rotary shaft; a biasing portion that is disposed on the opposite side of the armature with respect to the gap retaining member and that generates a biasing force in the axial direction, a fixing force of the gap retaining member to the rotating shaft is smaller than an attractive force between the yoke and the armature due to a magnetic force of the coil, and is larger than a biasing force of the biasing portion; Electromagnetic coupling device.

2. The electromagnetic coupling device according to claim 1 , further comprising a spacer provided between the armature and the gap retaining member.

3. 3. The electromagnetic coupling device according to claim 1, wherein a back surface of the armature facing the yoke serves as a contact surface against which a tip end surface of the rotary shaft comes into contact.

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