JP6458766B2 - Power transmission device - Google Patents

Description

  The present invention relates to a power transmission device that transmits a driving force to a rotating shaft of a device to be driven.

  For example, an air conditioner for a vehicle is provided with a compressor for compressing and sending out refrigerant in a refrigeration cycle. The compressor is driven using the driving force of the internal combustion engine of the vehicle. Specifically, the driving force of the internal combustion engine is transmitted to the rotating shaft of the compressor via the belt, and the rotating shaft rotates to compress the refrigerant in the compressor. In such a configuration, a power transmission device is often provided between the compressor and the internal combustion engine so that the compressor can be temporarily stopped when the internal combustion engine is operating (for example, (See Patent Document 1 below).

  The power transmission device is also referred to as a so-called “electromagnetic clutch”. The power transmission device includes a first rotating body that is rotated by a driving force of the internal combustion engine, a second rotating body that is fixed to a rotating shaft of a compressor (drive target device), a first rotating body, and a second rotating body. An electromagnet that generates an electromagnetic force therebetween.

  When the electromagnetic force is generated by the electromagnet, the first rotating body and the second rotating body are connected by the electromagnetic force. For this reason, the whole of the first rotating body, the second rotating body, and the rotating shaft are integrated, and these are rotated by the driving force of the internal combustion engine. That is, the driving force of the internal combustion engine is transmitted to the rotating shaft of the compressor, thereby driving the compressor.

  On the other hand, when no electromagnetic force is generated by the electromagnet, the connection between the first rotating body and the second rotating body is released. For this reason, the first rotating body continues to rotate by the driving force of the internal combustion engine, but the driving force is not transmitted to the second rotating body. Since the second rotating body and the rotating shaft do not rotate, the compressor stops its operation.

  In many cases, the connection between the second rotating body and the rotating shaft is achieved by screwing a female screw formed on the inner peripheral surface of the second rotating body and a male screw formed on the outer peripheral surface of the rotating shaft. It has been realized. When the rotational force of the second rotating body is transmitted to the rotating shaft and the compressor is driven by this, the axial force in the direction along the central axis is applied to the rotating shaft due to the above screw number. It is in the state.

JP 2011-158003 A

  By the way, in the compressor of the refrigeration cycle, the rotating shaft may be locked due to the biting of foreign matter or lack of lubricating oil. If the rotating shaft is locked in a state where electromagnetic force is generated by the electromagnet, that is, in a state where the first rotating body and the second rotating body are connected and rotating together, the space between the second rotating body and the rotating shaft A large rotational force will work. In such a state, the axial force applied to the rotating shaft also increases. The rotating shaft is pulled with a large force in the axial direction, and in some cases, the rotating shaft may be damaged.

  For this reason, it is necessary to take additional safety measures such as providing a stopper as described in Patent Document 1, for example, so that some parts do not fall off from the power transmission device or the drive target device. was there. As a result, problems such as an increase in manufacturing cost and complexity of the apparatus have occurred.

  The present invention has been made in view of such a problem, and the purpose thereof is that the axial force applied to the rotating shaft becomes too large even when the rotating shaft of the device to be driven is locked. An object of the present invention is to provide a power transmission device that does not end up.

  In order to solve the above-described problems, a power transmission device according to the present invention is a power transmission device (10) that transmits a driving force to a rotating shaft (520) of a device to be driven (50), and includes a driving force from the outside. The first rotating body (100) that rotates in response to the first rotating body and the second rotating body (200) that rotates together with the first rotating body by generating electromagnetic force. An electromagnet (300) to be provided. Further, in this power transmission device, the female screw (213) formed on the second rotating body and the male screw (521) formed on the rotating shaft are screwed, and the force along the central axis of the rotating shaft The second rotating body and the rotating shaft are configured to rotate together in a state where the axial force is applied to the rotating shaft. Further, the power transmission device includes an axial force suppression unit (S1, S2, S3) that prevents the axial force from becoming excessively large by preventing the relative rotation of the second rotating body with respect to the rotating shaft. Is provided.

  In the power transmission device having such a configuration, even if the rotating shaft is locked, the relative rotation of the second rotating body with respect to the rotating shaft is hindered by the axial force suppressing portion. As a result, an increase in the axial force associated with the rotation is prevented, so that the axial force applied to the rotating shaft does not become too large.

  According to the present invention, there is provided a power transmission device in which the axial force applied to the rotation shaft does not become too large even when the rotation shaft of the device to be driven is locked.

It is a figure which shows typically the structure of the power transmission device which concerns on 1st Embodiment of this invention, and the vehicle air conditioner provided with the said power transmission device. It is sectional drawing which shows the internal structure of a power transmission device. It is a figure which shows the structure of the part connected to the rotating shaft of a compressor. It is a figure which shows the structure of the part connected to the rotating shaft of a compressor among the power transmission devices which concern on 2nd Embodiment of this invention. It is a figure which shows the structure of the part connected to the rotating shaft of a compressor among the power transmission devices which concern on 3rd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same constituent elements in the drawings will be denoted by the same reference numerals as much as possible, and redundant description will be omitted.

  The power transmission device 10 according to the first embodiment of the present invention is provided in a part of the vehicle air conditioner AS. First, the configuration of the vehicle air conditioner AS will be described with reference to FIG. The vehicle air conditioner AS is configured as a refrigeration cycle that operates by obtaining a driving force from an internal combustion engine 20 of a vehicle (the whole is not shown). The vehicle air conditioner AS includes a circulation pipe 90, a compressor 50, a condenser 60, an expansion valve 70, and an evaporator 80.

  The circulation pipe 90 is a pipe through which the refrigerant of the refrigeration cycle circulates. In FIG. 1, the direction in which the refrigerant flows in the circulation pipe 90 is indicated by a plurality of arrows.

  The compressor 50 is a device (compressor) that compresses and sends out refrigerant so that the refrigerant circulates through the circulation pipe 90. The compressor 50 has a case 510 and a rotating shaft 520. A fixed scroll and a movable scroll (not shown) are accommodated in the case 510. The compressor 50 is configured to change the volume of a space formed between the two by moving the movable scroll relative to the fixed scroll to compress and feed out the refrigerant. In addition, since a well-known thing can be employ | adopted as a structure of such a compressor 50, the specific illustration and description are abbreviate | omitted.

  The rotating shaft 520 is a substantially cylindrical member, and protrudes outward from the case 510. In the present embodiment, the rotating shaft 520 is made of carbon steel for machine structure (S55C). The rotating shaft 520 is a shaft for receiving from the outside a driving force necessary for the compressor 50 to perform the above-described operation. When the rotating shaft 520 is rotated around its central axis by an external driving force, the compressor 50 compresses and delivers the refrigerant. A configuration for transmitting the driving force to the rotating shaft 520 and rotating it will be described later.

  The condenser 60 is provided at a position on the downstream side of the compressor 50 in the circulation pipe 90. The condenser 60 is a heat exchanger for receiving the high-temperature and high-pressure refrigerant sent from the compressor 50 and condensing the refrigerant by heat exchange with air. As the refrigerant passes through the condenser 60, heat is taken away from the air. As a result, the refrigerant condenses and changes from the gas phase to the liquid phase, and then flows toward the expansion valve 70.

  The expansion valve 70 is provided at a position on the downstream side of the condenser 60 in the circulation pipe 90. The expansion valve 70 is for reducing the temperature and the pressure by allowing the refrigerant discharged from the condenser 60 to pass through a throttle provided inside. The refrigerant that has passed through the expansion valve 70 and has become low temperature and low pressure flows toward the evaporator 80.

  The evaporator 80 is provided at a position downstream of the expansion valve 70 in the circulation pipe 90. The evaporator 80 is a heat exchanger that receives the refrigerant that has passed through the expansion valve 70 and has become low temperature and low pressure, and evaporates the refrigerant by heat exchange with air. The refrigerant removes heat from the air as it passes through the evaporator 80. As a result, the refrigerant evaporates and changes from the liquid phase to the gas phase, and then flows toward the compressor 50. Then, it is compressed again by the compressor 50 and sent out toward the condenser 60. In addition, due to the heat exchange in the evaporator 80, the air is deprived of heat from the refrigerant and decreases its temperature. Thereafter, it is blown out into the passenger compartment as conditioned air.

  An internal combustion engine 20 shown in FIG. 1 is an engine that generates a driving force necessary for traveling of a vehicle. The internal combustion engine 20 has an output shaft 21. The output shaft 21 is a substantially cylindrical shaft, and rotates around its central axis by the driving force of the internal combustion engine 20. The rotational force of the output shaft 21 is converted into the rotational force of the wheels via a transmission (not shown) and the vehicle is caused to travel.

  A pulley 30 is provided on the output shaft 21. When the internal combustion engine 20 is operating, the output shaft 21 and the pulley 30 rotate together. A belt 40 is hung between the pulley 30 and the power transmission device 10. As a result, the driving force of the internal combustion engine 20 is transmitted to the rotating shaft 520 via the belt 40 and the power transmission device 10 to rotate the rotating shaft 520 around its central axis.

  The configuration of the power transmission device 10 will be described with reference to FIG. FIG. 2 is a cross-sectional view showing a state where the power transmission device 10 is cut by a plane including the central axis AX of the rotation shaft 520. In addition, about the case 510, the rotating shaft 520, etc., some external appearances are shown instead of a cross section.

  The power transmission device 10 includes a first rotating body 100, a second rotating body 200, and an electromagnet 300.

  The first rotating body 100 is a member that directly receives the driving force from the belt 40 and rotates. The entire outer shape of the first rotating body 100 is formed in a substantially cylindrical shape, and is provided in a state where the central axis thereof coincides with the central axis AX of the rotating shaft 520. The first rotating body 100 includes an outer cylinder part 110, an inner cylinder part 120, and a connecting part 130.

  The outer cylinder part 110 is a part located in the outermost periphery side among the 1st rotary bodies 100, Comprising: The shape is a substantially cylindrical shape. Further, the central axis of the outer cylinder portion 110 coincides with the central axis AX. A plurality of grooves are formed on the outer surface of the outer cylinder portion 110 along the circumferential direction, and a belt 40 (not shown in FIG. 2) is hung on the grooves. For this reason, the driving force of the internal combustion engine 20 is transmitted to the outer peripheral surface of the outer cylinder part 110 via the belt 40, and rotates the 1st rotary body 100 around the central axis AX.

  The inner cylinder part 120 is a part located inside the outer cylinder part 110 among the 1st rotary bodies 100, Comprising: The shape is a substantially cylindrical shape. Similar to the outer cylinder part 110, the central axis of the inner cylinder part 120 also coincides with the central axis AX. A space is formed between the outer peripheral surface of the inner cylindrical portion 120 and the inner peripheral surface of the outer cylindrical portion 110, and an electromagnet 300 described later is disposed in the space.

  Further, a support portion 512 that is a part of the case 510 is provided at a position further inside than the inner peripheral surface of the inner cylinder portion 120. The support portion 512 is formed so as to extend along the central axis AX from the surface of the case 510 that faces the power transmission device 10. The support portion 512 is formed in a cylindrical shape that surrounds the periphery of the rotation shaft 520. A bearing 410 is provided between the outer peripheral surface of the support portion 512 and the outer peripheral surface of the inner cylinder portion 120. The first rotating body 100 is supported by the bearing 410 so as to be rotatable around the central axis AX.

  The connecting part 130 is a part that connects the inner cylinder part 120 and the outer cylinder part 110. The connecting portion 130 is generally formed in a flat plate shape, and is interposed between an armature 230 (described later) and an electromagnet 300. A surface of the connecting portion 130 opposite to the case 510 is a friction surface 131 that faces the armature 230.

  The second rotating body 200 is a member fixed to the rotating shaft 520 so as to rotate together with the rotating shaft 520. When the second rotating body 200 is connected to the first rotating body 100 by electromagnetic force generated by an electromagnet 300 described later, the second rotating body 200 rotates together with the first rotating body 100. That is, the driving force transmitted from the internal combustion engine 20 to the first rotating body 100 via the belt 40 is also transmitted to the second rotating body 200 and the rotating shaft 520, and the refrigerant is compressed and delivered by the compressor 50. It becomes a state.

  The second rotating body 200 has a hub 210, a leaf spring 220, and an armature 230. The hub 210 is a part fixed to the rotating shaft 520. The hub 210 has a cylindrical portion 212 and a flange portion 211. The cylindrical portion 212 has a substantially cylindrical shape, and its central axis coincides with the central axis AX. In addition, a through hole 215 is formed at the center of the cylindrical portion 212 along the central axis AX. A female screw 213 is formed on the inner peripheral surface of the through hole 215. In the present embodiment, the hub 210 is made of carbon steel for machine structure (S35C).

  A male screw 521 is formed on the outer peripheral surface of the rotation shaft 520. The rotating shaft 520 is inserted through the through hole 215, and the male screw 521 and the female screw 213 are screwed.

  The flange portion 211 is a portion formed so as to extend from the end portion of the cylindrical portion 212 opposite to the compressor 50 side toward the outer peripheral side (side away from the center axis AX).

  The leaf spring 220 is a member for supporting the armature 230. The leaf spring 220 is formed in a disc shape, and a through hole 221 is formed at the center thereof. The cylindrical portion 212 of the hub 210 is inserted through the through hole 221. A central portion (a portion near the through hole 221) of the leaf spring 220 is in contact with the surface of the flange portion 211 and is fixed to the flange portion 211.

  The armature 230 is fixed to a portion of the leaf spring 220 on the outer peripheral side of the portion fixed to the flange portion 211. The armature 230 is in contact with the surface of the leaf spring 220 on the compressor 50 side, and is fixed to the leaf spring 220 by rivets 461.

  A portion of the leaf spring 220 that holds the armature 230 can move in a direction along the central axis AX by elastic deformation of the leaf spring 220. When the electromagnetic force of the electromagnet 300 is not generated, a gap is formed between the armature 230 and the connecting portion 130 as shown in FIG. On the other hand, when the electromagnetic force of the electromagnet 300 is generated, the armature 230 moves to the compressor 50 side by the electromagnetic force, and the armature 230 comes into contact with the connecting portion 130.

  The armature 230 is a disk-shaped member made of a magnetic material, and a through hole 235 is formed at the center thereof. The armature 230 is supported by the leaf spring 220 as described above at a position facing the connecting portion 130 of the first rotating body 100. A surface of the armature 230 that faces the connecting portion 130 is a friction surface 231. When the electromagnetic force of the electromagnet 300 is generated, the friction surface 231 of the armature 230 and the friction surface 131 of the connecting portion 130 are in contact with each other, and the friction force acts between them. Due to the frictional force, the first rotating body 100 and the second rotating body 200 are connected to each other, and these rotate together.

  The electromagnet 300 includes a coil 310 and a core 320. The coil 310 is supplied with current and generates magnetic flux. The core 320 is a magnetic body disposed so as to surround the outside of the coil 310 and is a member that forms part of a magnetic circuit through which the magnetic flux generated by the coil 310 passes. The core 320 is provided so as to extend between the coil 310 and the outer cylinder part 110, between the coil 310 and the case 510, and between the coil 310 and the inner cylinder part 120.

  When a current flows through the coil 310, a magnetic flux is generated, and the magnetic flux passes through a magnetic circuit including the core 320, the outer cylinder part 110, the connecting part 130, the armature 230, and the inner cylinder part 120. As a result, an electromagnetic force that causes the armature 230 to face the connecting portion 130 is generated, and the friction surface 231 of the armature 230 and the friction surface 131 of the connecting portion 130 come into contact with each other. That is, the first rotating body 100 and the second rotating body 200 are connected to each other. The driving force from the internal combustion engine 20 is transmitted to the rotating shaft 520, and the refrigerant is compressed and delivered by the rotating shaft 520.

  When no current flows through the coil 310, the electromagnetic force is not generated. As a result, a gap is formed between the armature 230 and the connecting portion 130 by the restoring force of the leaf spring 220. As a result, the connection between the first rotating body 100 and the second rotating body 200 is released, and the driving force from the internal combustion engine 20 is not transmitted to the rotating shaft 520, so the compressor 50 stops its operation.

  Other configurations will be described. A holding ring 511 is formed in a portion of the case 510 that becomes the base of the support portion 512. The retaining ring 511 is a cylindrical portion formed so as to slightly protrude from the surface of the case 510. The central axis of the holding ring 511 coincides with the central axis AX. The outer diameter of the holding ring 511 is larger than the outer diameter of the support portion 512. The end surface of the holding ring 511 is in contact with the end surface of the bearing 410 on the case 510 side, thereby supporting the bearing 410.

  A groove 514 is formed along the circumferential direction on the outer surface in the vicinity of the tip of the support portion 512. A circlip 432 is fitted in the groove 514. The circlip 432 is in contact with the end surface of the bearing 410 opposite to the case 510. The inner surface of the groove 514 is tapered. Therefore, the elastic force that the circlip 432 tends to move toward the center axis AX is converted into a force that presses the circlip 432 against the bearing 410, that is, a force that urges the bearing 410 toward the holding ring 511. As a result, the bearing 410 is held in a state of being sandwiched between the circlip 432 and the holding ring 511.

  An arm support 420 is fixed to the surface of the electromagnet 300 on the case 510 side. The arm support 420 is a disk-shaped member, and a through hole 421 is formed at the center thereof. The holding ring 511 of the case 510 is inserted through the through hole 421.

  A groove 513 is formed on the side surface of the holding ring 511 along the circumferential direction thereof. A circlip 431 is fitted in the groove 513. The circlip 431 is in contact with the surface of the arm support 420 opposite to the case 510. The inner surface of the groove 513 is tapered. Therefore, the elastic force that the circlip 431 tends to move toward the central axis AX is converted into a force that presses the circlip 431 against the arm support 420, that is, a force that urges the arm support 420 toward the case 510. As a result, the arm support 420 is held in a state of being sandwiched between the circlip 431 and the case 510.

  The connection between the rotating shaft 520 and the hub 210 will be further described. Of the rotating shaft 520, a diameter-enlarged portion 522 having a larger diameter than other portions is provided in a portion closer to the case 510 than the male screw 521. In addition, a shim 440 and a washer 450 are sandwiched between the end surface of the cylindrical portion 212 on the case 510 side and the end surface of the enlarged diameter portion 522. The shim 440 and the washer 450 are both metal members formed in an annular shape.

  When an electromagnetic force is generated by the electromagnet 300 and the second rotating body 200 rotates together with the first rotating body 100, the hub 210 receives a force in a direction rotating relative to the rotating shaft 520. In other words, it receives a force in the direction of tightening the male screw 521 and the female screw 213 that are screwed. As a result, the hub 210 tends to move in the direction approaching the case 510 along the central axis AX, so that the end surface of the hub 210 is pressed against the shim 440. A strong frictional force is generated at a portion where the hub 210, the shim 440, the washer 450, and the enlarged diameter portion 522 are adjacent to each other. Due to this frictional force, the rotational force of the hub 210 is transmitted to the rotating shaft 520, and the rotating shaft 520 rotates.

  At this time, a force in a direction away from the case 510 along the central axis AX, that is, an axial force is applied to the rotating shaft 520 as a reaction force of the force that the hub 210 is pressed against the shim 440 side. The magnitude of the axial force increases as the hub 210 begins to rotate. However, after the rotating shaft 520 begins to rotate together with the hub 210, the magnitude of the axial force is maintained at a substantially constant magnitude. The magnitude of the axial force at this time is sufficiently smaller than the breaking strength of the rotating shaft 520.

  By the way, like the compressor of a general refrigeration cycle, in the compressor 50, the rotating shaft 520 is locked (a state where it cannot rotate) due to the biting of foreign matter, lack of lubricating oil, and the like. It may become. If the rotating shaft 520 is locked in a state where the electromagnetic force is generated by the electromagnet 300, that is, in a state where the first rotating body 100 and the second rotating body 200 are connected, between the hub 210 and the rotating shaft 520. A large rotational force acts, and the male screw 521 and the female screw 213 are tightened with a strong force. As a result, the axial force applied to the rotating shaft 520 is also increased. Since the rotating shaft 520 is pulled with a large force along the central axis AX, the rotating shaft 520 may be damaged in some cases.

  Therefore, the power transmission device 10 according to the present embodiment is devised to prevent the above situation. The device will be described with reference to FIG.

  In FIG. 3, a portion of the inner surface of the through hole 215 that is closer to the flange portion 211 than the female screw 213 is surrounded by a dotted line S <b> 1. Hereinafter, this part is referred to as “interference part S1”. The interference portion S1 is a portion adjacent to the female screw 213 in the hub 210.

  In the present embodiment, the inner diameter of the through hole 215 in the interference part S1 is smaller than the outer diameter of the male screw 521. That is, the distance from the inner surface of the interference portion S1 to the central axis AX is smaller than the distance from the peak of the male screw 521 to the central axis AX.

  When the rotating shaft 520 is locked from the state shown in FIG. 3, the male screw 521 and the female screw 213 are tightened with a strong force as described above. As a result, the rotating shaft 520 attempts to move in the direction of the arrow AR1, and the cylindrical portion 212 of the hub 210 attempts to move in the direction indicated by the arrow AR2.

  However, immediately after that, since the male screw 521 and the interference part S1 are in a buffered state, the relative rotation of the hub 210 (second rotating body 200) with respect to the rotating shaft 520 is immediately prevented. As a result, the axial force applied to the rotating shaft 520 does not increase any further, so that the axial force does not exceed the breaking strength of the rotating shaft 520. The interference part S1 functions as an “axial force suppressing part” in the present embodiment.

  In this embodiment, the interference part S1 which is an axial force suppression part is formed integrally with the hub 210 which is a member in which the female screw 213 is formed. The hub 210 is formed of S35C as described above, and its hardness is lower than the hardness of the rotating shaft 520. For this reason, immediately after the rotation shaft 520 is locked, the male screw 521 slightly advances while deforming the interference portion S1 (that is, cutting the screw).

  That is, the hub 210 is stopped by receiving a large resistance force due to the interference between the male screw 521 and the interference portion S1, but the deceleration is slight because the interference portion S1 serves as a cushion during the stop. Has become moderate. Thereby, the impact sound caused by the interference between the male screw 521 and the interference part S1 is suppressed, and it is possible to prevent the vehicle occupant from feeling uncomfortable.

  A second embodiment of the present invention will be described with reference to FIG. In the present embodiment, only the configuration of the hub 210 is different from that of the first embodiment, and other configurations are the same as those of the first embodiment. Below, only a different point from 1st Embodiment is demonstrated, and the description is abbreviate | omitted suitably about the point which is common in 1st Embodiment.

  In this embodiment, the interference part S1 in the first embodiment is replaced with a ring S2 which is a separate member from the hub 210. The ring S2 is formed of a material different from the material of the member (that is, the hub 210) in which the female screw 213 is formed in the second rotating body 200. As a material of such a ring S2, it is preferable to use a material having a lower hardness than both the female screw 213 and the male screw 521. In this embodiment, rubber is used as the material for the ring S2. Resin may be used instead of rubber.

  Also in this embodiment, when the rotation shaft 520 is locked, the male screw 521 and the ring S2 are buffered, and an increase in the axial force applied to the rotation shaft 520 is suppressed. The ring S2 functions as an “axial force suppression unit” in the present embodiment.

  In the present embodiment, since the hardness of the ring S2 that is the axial force suppressing portion is further smaller, the deceleration of the hub 210 becomes more gradual. For this reason, the impact sound generated by the interference between the male screw 521 and the ring S2 is further suppressed.

  A third embodiment of the present invention will be described with reference to FIG. In this embodiment, only the configuration of the hub 210 and the rotating shaft 520 is different from that of the first embodiment, and other configurations are the same as those of the first embodiment. Below, only a different point from 1st Embodiment is demonstrated, and the description is abbreviate | omitted suitably about the point which is common in 1st Embodiment.

  In the present embodiment, the inner diameter of the inner surface of the through hole 215 closer to the flange 211 than the female screw 213, that is, the portion corresponding to the interference portion S1 in the first embodiment is larger than the outer diameter of the male screw 521. It is getting bigger.

  In FIG. 5, a portion of the outer peripheral surface of the rotating shaft 520 closer to the diameter-enlarged portion 522 than the male screw 521 is surrounded by a dotted line S3. Hereinafter, this part is referred to as “interference part S3”. The interference portion S3 is a portion adjacent to the male screw 521 in the rotating shaft 520.

  In the present embodiment, the outer diameter of the interference portion S3 of the rotating shaft 520 is larger than the inner diameter of the female screw 213. That is, the distance from the outer peripheral surface of the interference part S3 to the central axis AX is larger than the distance from the peak of the female screw 213 to the central axis AX.

  When the rotating shaft 520 is locked from the state shown in FIG. 5, the male screw 521 and the female screw 213 are tightened with a strong force as described above. As a result, the rotating shaft 520 attempts to move in the direction of the arrow AR1, and the cylindrical portion 212 of the hub 210 attempts to move in the direction indicated by the arrow AR2.

  However, immediately after that, since the female screw 213 and the interference part S3 are in a buffered state, the relative rotation of the hub 210 (second rotating body 200) with respect to the rotating shaft 520 is immediately prevented. As a result, the axial force applied to the rotating shaft 520 does not increase any further, so that the axial force does not exceed the breaking strength of the rotating shaft 520. The interference part S3 functions as an “axial force suppressing part” in the present embodiment.

  Thus, even when the axial force suppression portion is formed on the rotating shaft 520, the same effects as those of the first embodiment are obtained. However, in this case, the female screw 213, which is a low-grade material, does not cut a screw on the rotating shaft 520 (interference portion S3), which is a high-hardness material. For this reason, when the rotation shaft 520 is locked, the hub 210 stops more rapidly than in the case of the first embodiment, and a large impact sound is generated accordingly. The first embodiment is preferable to the present embodiment from the viewpoint of reducing the impact sound.

  In the above, the example in which the drive target device to which the driving force is transmitted by the power transmission device 10 is the compressor 50 of the refrigeration cycle has been described. It is needless to say that the same effect as described above can be obtained even if an apparatus other than the compressor 50 is used as the drive target apparatus instead of such an aspect.

  The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In other words, those specific examples that have been appropriately modified by those skilled in the art are also included in the scope of the present invention as long as they have the characteristics of the present invention. For example, the elements included in each of the specific examples described above and their arrangement, materials, conditions, shapes, sizes, and the like are not limited to those illustrated, but can be changed as appropriate. Moreover, each element with which each embodiment mentioned above is provided can be combined as long as technically possible, and the combination of these is also included in the scope of the present invention as long as it includes the features of the present invention.

10: Power transmission device 50: Compressor (device to be driven)
100: first rotating body 200: second rotating body 213: female screw 300: electromagnet 520: rotating shaft 521: male screws S1, S3: interference section S2: ring

Claims (8)

A power transmission device (10) for transmitting a driving force to a rotating shaft (520) of a device to be driven (50),
A first rotating body (100) that rotates in response to an external driving force;
A second rotating body (200) that rotates together with the first rotating body by being coupled to the first rotating body by electromagnetic force;
An electromagnet (300) for generating the electromagnetic force,
The female screw (213) formed on the second rotating body and the male screw (521) formed on the rotating shaft are screwed, and an axial force that is a force along the central axis of the rotating shaft is generated. The second rotating body and the rotating shaft are configured to rotate together while being applied to the rotating shaft,
Power provided with an axial force suppressing portion (S1, S2, S3) that prevents the axial force from becoming too large by preventing relative rotation of the second rotating body with respect to the rotating shaft. Transmission device. The axial force suppressing portion (S1) is provided in a portion adjacent to the female screw in the second rotating body,
2. The power transmission device according to claim 1, wherein relative rotation of the second rotating body with respect to the rotation shaft is prevented by interference between the male screw and the axial force suppressing portion.   The power transmission device according to claim 2, wherein the axial force suppression unit is formed integrally with a member of the second rotating body in which the female screw is formed.   The power transmission device according to claim 3, wherein the axial force suppression unit and the second rotating body are formed of a material having a hardness lower than that of the male screw.   The power transmission device according to claim 2, wherein the axial force suppressing portion (S2) is formed of a material different from a material of a member of the second rotating body on which the female screw is formed.   The power transmission device according to claim 5, wherein the axial force suppressing portion is formed of a material having a hardness lower than any of the female screw and the male screw.   The power transmission device according to claim 6, wherein the axial force suppression portion is made of rubber. The axial force suppressing portion (S3) is provided in a portion of the rotating shaft adjacent to the male screw,
The power transmission device according to claim 1, wherein relative rotation of the second rotating body with respect to the rotating shaft is prevented by interference between the female screw and the axial force suppressing portion.

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