JP2018132105A - Power transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power transmission device which can achieve miniaturization and can reduce the number of components.SOLUTION: A limiter 15 is made of a nonmagnetic material, is connected to an inner hub 16, and is attached to an armature 14. When a rotating shaft 21 is stopped by locking, the limiter 15 is broken, and power transmission from the armature 14 to the inner hub 16 is blocked. The limiter 15 is made of the nonmagnetic material, and there is no risk of being captured by the armature 14 with electromagnetic force from an electromagnet 12. The inner hub 16 connected to the rotating shaft 21 does not come off even when connection between the limiter 15 and the armature 14 is released. The limiter 15 is connected with the inner hub 16 by a plate spring 18, and does not come off even when connection with the armature 14 is released. A component for preventing coming off can be dispensed with, and reduction of the size and the number of components can be achieved.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a power transmission device that transmits a rotational driving force output from a driving source to a device to be driven.

  Conventionally, a drive-side rotator that rotates by a rotational drive force output from a drive source, a driven-side rotator that rotates together with the rotation shaft of the drive target device by being connected to the drive-side rotator, 2. Description of the Related Art There is known a power transmission device that includes an electromagnet that generates an electromagnetic force that is coupled to a drive-side rotator and that transmits a rotational drive force output from a drive source to a drive target device.

  In this type of power transmission device, in order to prevent an excessive load from being applied to the drive source side when the device to be driven is locked, a function for quickly interrupting transmission of the rotational driving force is required.

  For this purpose, there is known a device that is provided with a limiter that breaks when the device to be driven is locked, and that interrupts the transmission of the rotational driving force by breaking the limiter when locked (for example, see Patent Document 1).

JP 2011-158003 A

  However, since the power transmission device of Patent Document 1 is configured such that when the limiter breaks, the driven-side rotating body is separated from the rotating shaft, a cover for preventing the driven-side rotating body from falling off is attached to the tip of the rotating shaft. ing. This is not preferable because it leads to an increase in the size of the power transmission device and an increase in the number of parts and an increase in work man-hours associated with attachment.

  In view of the above points, the present invention provides a power transmission device that can reduce the size of the physique and reduce the number of components compared to the prior art, while preventing the driven-side rotating body from falling off when the limiter breaks. The purpose is to provide.

In order to achieve the above object, the invention described in claim 1
A power transmission device (10) for transmitting a rotational driving force output from a driving source (6) to a drive target device (2),
A driving side rotating body (11) that rotates by a rotational driving force output from the driving source;
A driven-side rotator (13) that rotates together with the rotation shaft (21) of the device to be driven by being connected to the drive-side rotator;
An electromagnet (12) for generating an electromagnetic force for coupling the driven-side rotator to the drive-side rotator,
In the driven side rotating body,
An armature (14) attracted to the drive-side rotor by the electromagnetic force;
An inner hub (16) coupled to the rotating shaft;
A limiter (15) interposed between the armature and the inner hub,
The limiter is made of a non-magnetic material, and is connected to the armature and the inner hub to mediate power transmission from the armature to the inner hub,
The limiter is a power transmission device that is broken when the rotating shaft stops due to a lock, and is disconnected from the armature due to the breakage.

  The limiter interposed between the armature and the inner hub mediates the transmission of power from the armature to the inner hub, so if an electromagnetic force is generated by an electromagnet and the driven side rotator is connected to the drive side rotator, the drive source When the drive-side rotator is rotated by the rotational driving force output from, the driven-side rotator is rotated together with the rotation shaft of the drive target device. Thereby, the rotational drive force output from a drive source can be transmitted to a drive object apparatus.

  On the other hand, when the device to be driven is locked and the rotation shaft stops rotating, the limiter is broken and the connection between the limiter and the armature is released, so that power transmission from the armature to the inner hub is interrupted. Thereby, transmission of the rotational driving force from the power transmission device to the drive target device is cut off, and an excessive load on the drive source side due to the lock of the drive target device is prevented.

  Since the limiter is made of a non-magnetic material, there is no possibility of being caught by the armature due to the electromagnetic force exerted from the electromagnet to the armature.

  Since the inner hub is connected to the rotating shaft, the inner hub does not fall off even if the connection between the limiter and the armature is released. And since the limiter is connected with the inner hub, it will not fall off even if the connection with the armature is released.

  Therefore, parts for preventing the dropout such as a cover in the power transmission device of Patent Document 1 are not required. Therefore, it is possible to provide a power transmission device that can be made smaller in size than the conventional one and can reduce the number of parts.

  In addition, the code | symbol in the bracket | parenthesis in the said and the claim shows the correspondence of the term described in the claim, and the concrete thing etc. which illustrate the said term described in embodiment mentioned later. .

It is the whole refrigeration cycle lineblock diagram to which the power transmission device of an embodiment is applied. It is an axial sectional view of the power transmission device of the first embodiment. It is an axial sectional view of a state where a limiter is damaged in the power transmission device of the first embodiment. It is an axial sectional view of the power transmission device of the second embodiment. It is an axial sectional view of the power transmission device of the third embodiment. It is an axial sectional view of the power transmission device of the fourth embodiment.

  Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings.

(Embodiment 1)
A first embodiment will be described with reference to FIGS. In the present embodiment, an example in which the power transmission device 10 is applied to the compressor 2 of the vapor compression refrigeration cycle 1 shown in FIG. 1 will be described.

  The refrigeration cycle 1 functions as a device that adjusts the temperature of air blown into the vehicle interior in a vehicle air conditioner that performs air conditioning of the vehicle interior. The refrigeration cycle 1 includes a compressor 2 that compresses and discharges refrigerant, a radiator 3 that radiates heat discharged from the compressor 2, an expansion valve 4 that decompresses refrigerant flowing out of the radiator 3, and an expansion valve 4. An evaporator 5 that evaporates the decompressed refrigerant and exerts an endothermic action is connected in a ring shape.

  As the compressor 2, for example, a swash plate type variable capacity compressor can be adopted. In addition, as the compressor 2, as long as the refrigerant of the refrigeration cycle 1 is compressed and discharged by transmission of rotational driving force, other types of variable capacity compressors, fixed types such as a scroll type and a vane type are used. A capacity type compressor may be adopted.

  In the compressor 2 of the present embodiment, a part of the rotary shaft 21 passes through the cylindrical boss portion 22 and is exposed to the outside of the casing. The power transmission device 10 is attached to a portion of the rotating shaft 21 exposed to the outside.

  A rotational driving force output from the engine 6 is transmitted to the compressor 2 via the power transmission device 10.

  The power transmission device 10 is a device that intermittently transmits the rotational driving force output from the engine 6 that is a driving source for vehicle travel to the compressor 2 that is a driving target device. The power transmission device 10 is connected to the rotation output unit 6 a of the engine 6 via the V belt 7.

  FIG. 2 is a cross-sectional view of the upper half when the power transmission device 10 is cut along the axial direction of the rotary shaft 21 of the compressor 2.

  In addition, AD shown in FIG. 2 has shown the rotating shaft direction prescribed | regulated as the direction extended along the axial direction of the rotating shaft 21. As shown in FIG. Moreover, RD shown in FIG. 2 has shown the radial direction prescribed | regulated as a direction orthogonal to a rotating shaft direction. CL shown in FIG. 2 indicates the center line of the rotating shaft 21.

  As shown in FIG. 2, the power transmission device 10 includes a pulley 11, a driven side rotating body 13 that rotates together with the rotating shaft 21 of the compressor 2 by being connected to the pulley 11, a driven side rotating body 13, and the pulley 11. It has an electromagnet 12 that generates an electromagnetic force to be coupled.

  The pulley 11 constitutes a drive-side rotator that is rotated by a rotational driving force output from the engine 6. The pulley 11 of this embodiment has an outer cylindrical portion 111, an inner cylindrical portion 112, and an end surface portion 113.

  The outer cylindrical portion 111 is configured in a cylindrical shape and is disposed coaxially with the rotation shaft 21. The inner cylindrical portion 112 is configured in a cylindrical shape, is disposed on the inner peripheral side of the outer cylindrical portion 111, and is disposed coaxially with the rotation shaft 21.

  The end surface portion 113 is a connecting portion that connects one end sides of the outer cylindrical portion 111 and the inner cylindrical portion 112 in the rotation axis direction AD. The end surface portion 113 is configured in a disk shape. That is, the end surface portion 113 extends in the radial direction RD of the rotating shaft 21, and a circular through hole penetrating the front and back is formed in the center portion thereof.

  The pulley 11 of this embodiment has a C-shaped cross section in the rotation axis direction AD. An annular space having the end surface portion 113 as a bottom surface portion is formed between the outer cylindrical portion 111 and the inner cylindrical portion 112.

  A space formed between the outer cylindrical portion 111 and the inner cylindrical portion 112 is coaxial with the rotation shaft 21. An electromagnet 12 is disposed in a space formed between the outer cylindrical portion 111 and the inner cylindrical portion 112.

  Here, the electromagnet 12 includes a stator 121, a coil 122 disposed inside the stator 121, and the like. The stator 121 is formed in a ring shape with a ferromagnetic material such as iron. The coil 122 is fixed to the stator 121 in a state of being molded with an insulating resin material such as an epoxy resin. The electromagnet 12 is energized by a control voltage output from an air conditioning control device (not shown).

  The outer cylindrical portion 111, the inner cylindrical portion 112, and the end surface portion 113 are integrally formed of a ferromagnetic material such as iron. The outer cylindrical portion 111, the inner cylindrical portion 112, and the end surface portion 113 constitute a part of a magnetic circuit generated by energizing the electromagnet 12.

  On the outer peripheral side of the outer cylindrical portion 111, a resin-made V groove portion 114 in which a plurality of V-shaped grooves are formed is formed. A V-belt 7 that transmits the rotational driving force output from the engine 6 is stretched over the V-groove 114.

  The outer peripheral side of the ball bearing 17 is fixed to the inner peripheral side of the inner cylindrical portion 112. The inner peripheral side of the ball bearing 17 is externally fitted to the boss portion 22 (not shown in FIG. 2). Thereby, the pulley 11 is rotatably attached to the housing of the compressor 2.

  Further, the outer surface on one end side in the rotation axis direction AD in the end surface portion 113 forms a friction surface that comes into contact with the armature 14 when the pulley 11 and the armature 14 of the driven side rotating body 13 described later are connected. Yes.

  In the present embodiment, although not shown, a friction member for increasing the friction coefficient of the end surface portion 113 is disposed on a part of the surface of the end surface portion 113. The friction member is made of a nonmagnetic material. As the friction member, a material obtained by solidifying alumina with a resin, a sintered body of metal powder such as aluminum, or the like can be used.

  Subsequently, the driven side rotating body 13 includes an armature 14, a limiter 15, an inner hub 16, a leaf spring 18, and the like.

  The armature 14 is an annular plate member that extends in the radial direction RD and has a through-hole penetrating the front and back at the center.

  The armature 14 is made of a ferromagnetic material such as iron. The armature 14 together with the pulley 11 constitutes a part of a magnetic circuit for electromagnetic force generated when the electromagnet 12 is energized.

  The armature 14 is disposed to face the end surface portion 113 of the pulley 11 with a predetermined minute gap (for example, about 0.5 mm). Of the two flat portions 141 and 142 of the armature 14, the flat portion 141 facing the end surface portion 113 of the pulley 11 has a friction surface that contacts the end surface portion 113 when the pulley 11 and the armature 14 are connected. Forming.

  Further, the armature 14 of the present embodiment has a magnetic shielding groove 143 formed in the middle portion in the radial direction. A plurality of the groove portions 143 are formed in an arc shape extending along the circumferential direction of the armature 14. The armature 14 of the present embodiment is divided into an outer peripheral portion 144 located on the outer peripheral side of the groove portion 143 and an inner peripheral portion 145 located on the inner peripheral side of the groove portion 143. The inner peripheral surface of the inner peripheral portion 145 is provided with a screw thread over the entire periphery, forming a female screw 146.

  The limiter 15 is interposed between the armature 14 and the inner hub 16 in the power transmission path from the armature 14 to the inner hub 16. The limiter 15 is made of a nonmagnetic material. In this embodiment, it is formed of SUS304, but other austenitic stainless steels, copper alloys, aluminum alloys, and other metal materials can be used, and engineering plastics can also be used.

  The limiter 15 includes a main body portion 151 and a screw ring portion 152. The main body 151 is an annular plate member that extends in the radial direction RD and has a through hole formed through the front and back at the center. The threaded ring portion 152 is a ring-shaped member. The limiter 15 has a shape in which a threaded ring portion 152 is connected to the armature 14 side of the inner peripheral portion of the main body portion 151.

  The main body 151 faces the surface of the armature 14 opposite to the surface facing the electromagnet 12. Both the surface (inner surface 153) facing the armature 14 and the opposite surface (outer surface 154) of the main body 151 are flat.

  A screw thread is provided on the outer peripheral surface of the threaded ring portion 152 over the entire circumference to form a male screw 155. In addition, an annular groove 156 having a C-shaped cross-section is provided at a corner formed between the main body 151 and the threaded ring portion 152 so as to go around the threaded ring portion 152.

  The male screw 155 of the screw ring portion 152 is screwed with the female screw 146 of the armature 14, and the limiter 15 and the armature 14 are connected by this screwing. The inner surface 153 of the main body 151 is in close contact with the flat portion 142 of the armature 14.

  The male screw 155 and the female screw 146 are screwed in a right-handed manner. The armature 14 is centered on the center line CL in the direction from the front side to the back side in FIG. 2, and the limiter 15 is moved from the back side to the front side in FIG. When the armature 14 is relatively rotated in the direction of heading, the armature 14 is relatively moved in the left direction in FIG. 2, and the limiter 15 is relatively moved in the right direction in FIG.

  Further, the main body 151 of the limiter 15 is connected to an outer peripheral annular portion 182 of the leaf spring 18 described later by a fastening member 31 such as a rivet.

  The inner hub 16 forms a part of the driven side rotating body 13 and is also a member for connecting the limiter 15 connected to the armature 14 and the rotating shaft 21 of the compressor 2.

  The inner hub 16 is made of an iron-based metal material. The inner hub 16 of this embodiment has a cylindrical portion 161 and a flange portion 162.

  The cylindrical portion 161 is configured in a cylindrical shape, and is disposed coaxially with the rotation shaft 21.

  The cylindrical portion 161 is provided with an insertion hole 163, and a female screw 163 a is formed on the inner peripheral side of the insertion hole 163. One end side of the rotating shaft 21 is inserted into the insertion hole 163. A male screw (not shown) is formed on the outer periphery of the rotating shaft 21. The rotating shaft 21 and the inner hub 16 are connected by the male screw being screwed into the female screw 163a. The end of the rotating shaft 21 is housed inside the cylindrical portion 161 and does not protrude to the left of the flange face of the flange portion 162 in FIG.

  In addition, the screwing form of the female screw 163a of the insertion hole 163 and the rotating shaft 21 is opposite to the screwing form of the armature 14 (female screw 146) and the limiter 15 (male screw 155). That is, if one of these two screwing forms is a right-hand thread, the other is a left-hand thread.

  The cylindrical portion 161 is integrally formed with a flange portion 162 that extends from one end side in the rotational axis direction AD of the cylindrical portion 161 to the outside in the radial direction RD. The flange portion 162 is configured in a disc shape that extends in the radial direction RD. The flange portion 162 is connected to an inner peripheral annular portion 181 of the leaf spring 18 described later by a fastening member 32 such as a rivet.

  The leaf spring 18 is a member that applies a biasing force to the armature 14 in a direction away from the pulley 11. This biasing force creates a gap between the flat portion 141 of the armature 14 and the end surface portion 113 of the pulley 11 when the electromagnet 12 is not energized and generates no electromagnetic force.

  The leaf spring 18 is a circular plate-like member made of an iron-based metal material. The leaf spring 18 has an inner peripheral annular portion 181 whose central portion is open, and an outer peripheral annular portion 182 disposed outside the inner peripheral annular portion 181 in the radial direction RD. As described above, the leaf spring 18 has the inner peripheral annular portion 181 connected to the flange portion 162 of the inner hub 16 and the outer peripheral annular portion 182 connected to the main body portion 151 of the limiter 15.

  A plurality of opening window portions 183 are formed between the inner peripheral annular portion 181 and the outer peripheral annular portion 182. The plurality of opening windows 183 are formed at equal intervals in the circumferential direction of the leaf spring 18. Although not shown, a connecting portion 184 extending in the radial direction RD is formed between each of the plurality of opening window portions 183 in the leaf spring 18. By the connecting portion 184, the inner peripheral annular portion 181 and the outer peripheral annular portion 182 are integrally connected.

  The plate spring 18 is provided with a plate-like rubber elastic member 35. By the elastic member 35 and the fastening member 31, the outer peripheral annular portion 182 of the leaf spring 18 and the limiter 15 are integrally coupled. The elastic member 35 closes the plurality of opening windows described above, thereby reducing the possibility of dust entering from the leaf spring 18 to the limiter 15 and armature 14 side than the leaf spring 18. In addition, the elastic member 35 performs a torque transmission function between the leaf spring 18 and the limiter 15 and also functions to suppress vibration.

  Next, the operation of the power transmission device 10 of the present embodiment will be described.

  When the electromagnet 12 is in a non-energized state, the electromagnetic force of the electromagnet 12 is not generated. For this reason, the armature 14 is held at a position away from the end surface portion 113 of the pulley 11 by a biasing force of the leaf spring 18.

  Thus, the rotational driving force from the engine 6 is only transmitted to the pulley 11 via the V-belt 7 and is not transmitted to the armature 14, limiter 15 and inner hub 16, and only the pulley 11 is idled on the ball bearing 17. To do. That is, the compressor 2 that is the drive target device is stopped.

  On the other hand, when the electromagnet 12 is energized, an electromagnetic force of the electromagnet 12 is generated. The armature 14 is attracted to the pulley 11 by the electromagnetic force being attracted to the end face 113 side of the pulley 11 against the urging force of the leaf spring 18. As a result, the rotation of the pulley 11 is transmitted to the armature 14, and the driven-side rotator 13 including the leaf spring 18, the limiter 15, and the inner hub 16 rotates.

  At this time, if the compressor 2 is not locked, the rotation of the inner hub 16 is transmitted to the rotating shaft 21 of the compressor 2. Note that this rotation direction is a direction in which the armature 14 is rotated in the direction from the front surface to the back surface with the center line CL as the center in FIG. At this time, the limiter 15 is connected to the armature 14 and the inner hub 16 to mediate power transmission from the armature 14 to the inner hub 16.

  Thus, the compressor 2 operates by rotating the rotary shaft 21. That is, the rotational driving force output from the engine 6 is transmitted to the compressor 2 via the power transmission device 10, so that the compressor 2 operates.

On the other hand, when the compressor 2 is locked due to seizure or the like and the rotation shaft 21 stops and cannot rotate, the rotation of the inner hub 16 and the limiter 15 is blocked by the rotation shaft 21.
Accordingly, the torque acting between the limiter 15 and the armature 14 increases. When this torque becomes very large, the armature 14 rotates with respect to the limiter 15. By this rotation, an axial force is generated between the female screw 146 of the armature 14 and the male screw 155 of the limiter 15.

  This axial force acts as a force that pulls the screw ring 152 of the limiter 15 toward the armature 14. However, the inner surface 153 of the main body portion 151 of the limiter 15 is in close contact with the flat portion 142 of the armature 14 and is prevented from moving due to the axial force. For this reason, tensile stress is applied between the main body 151 and the threaded ring portion 152. This tensile stress acts intensively on the annular groove 156 provided at the corner between the main body 151 and the threaded ring portion 152.

  When the tensile stress exceeds a predetermined value, the limiter 15 is broken from the annular groove 156 as shown in FIG. 3, and the main body 151 and the threaded ring 152 are separated. FIG. 3 is a cross-sectional view of the power transmission device 10 for explaining a state in which the limiter 15 is broken, and AD, RD, and CL indicate the same as those in FIG.

  A series of parts from the limiter 15 to the inner hub 16 are separated from the armature 14 by the separation of the main body 151 and the threaded ring portion 152.

  Since the limiter 15 is made of a nonmagnetic material, the main body 151 is not likely to be caught by the armature 14 due to the electromagnetic force exerted from the electromagnet 12 to the armature 14. As a result, when the limiter 15 is broken, the possibility that the main body 151 is attracted to the armature 14 by the electromagnetic force and rotates together with the armature 14 is reduced.

  Therefore, although the rotation of the pulley 11 is transmitted to the armature 14, it is not transmitted to the rotating shaft 21, and the pulley 11, the armature 14 and the screwed ring portion 152 of the limiter 15 are idled on the rotating shaft 21. That is, transmission of the rotational driving force from the engine 6 to the compressor 2 is interrupted. Therefore, it is possible to prevent an excessive load from being applied to the drive source side due to the lock of the compressor 2 that is the drive target device.

  Note that, even after the limiter 15 is broken, the screwed ring portion 152 and the armature 14 are kept screwed together. Therefore, the screwed ring portion 152 separated from the main body portion 151 is held by the armature 14 to prevent falling off. Is done. Further, the main body 151 of the limiter 15 is connected to the inner hub 16 via the leaf spring 18, and the inner hub 16 is connected to the rotating shaft 21, so that the part extending from the main body 151 to the inner hub 16 is prevented from falling off. .

  Since the force that damages the limiter 15 when the rotating shaft 21 cannot rotate is derived from the axial force that acts on the limiter 15 by screwing between the limiter 15 and the armature 14, the armature 14 and the rotating shaft are simple in structure. The limiter 15 is surely broken when the torque acting between the two exceeds the limit value.

  In addition, the limiter 15 is provided with an annular groove 156 having a C-shaped cross section, and this annular groove 156 is the starting point of breakage, so that the torque acting between the armature 14 and the rotating shaft 21 is limited. When the value is exceeded, the limiter 15 is broken more quickly and reliably.

  The limiter 15 is broken and split into the main body 151 and the screw ring portion 152, but the main body 151, the leaf spring 18, and the inner hub 16 are held by the rotating shaft 21. The screw ring portion 152 is integrally screwed with the armature 14, but the main body portion 151 and the leaf spring 18 serve as a cover to prevent the armature 14 and the screw ring portion 152 from falling off. This is because the armature 14 and the leaf spring 18 partially overlap in the axial direction CL, and the armature 14 and the main body portion 151 partially overlap in the axial direction CL. Therefore, it is possible to prevent the parts constituting the driven-side rotating body 13 from falling off without using a part such as a cover.

  As described above, according to the power transmission device 10 of the present embodiment, when the compressor 2 that is the drive target device is locked due to seizure or the like, the rotational driving force is transmitted from the power transmission device 10 to the drive target device. Since it shuts off promptly, it is prevented that an excessive load is applied to the drive source side due to the lock of the drive target device.

  Even if the limiter 15 is broken, the broken main body 151 and screw ring portion 152 are prevented from falling off, and the armature 14 and the inner hub 16 are also prevented from falling off. Therefore, it is possible to prevent the parts constituting the driven-side rotating body 13 from falling off without using a part such as a cover. Therefore, the physique can be made smaller than before. Further, since the number of parts can be reduced, the cost can be reduced.

(Embodiment 2)
An example in which the armature and the limiter are screwed on the outer peripheral side of the armature will be described as a second embodiment with reference to FIG. In addition, since many parts are common with Embodiment 1, about these common parts, description is abbreviate | omitted using the same code | symbol.

  As in the first embodiment (see FIG. 1), the power transmission device 210 according to the present embodiment intermittently transmits the rotational driving force output from the engine 6 that is the drive source to the compressor 2 that is the drive target device. In this example, the apparatus is applied to the compressor 2 of the refrigeration cycle 1.

  FIG. 4 is a cross-sectional view of the upper half portion of the power transmission device 210 when cut along the axial direction of the rotary shaft 21 of the compressor 2. Note that the rotation axis direction AD, the radial direction RD, and the center line CL shown in FIG. 4 have the same meaning as in the first embodiment.

  As shown in FIG. 4, the armature 214 is an annular plate member that extends in the radial direction RD and has a through-hole penetrating the front and back at the center thereof, as in the first embodiment. 144 and an inner peripheral portion 145. The outer peripheral surface of the outer peripheral portion 144 is provided with a screw thread over the entire periphery to form a male screw 246. Others are the same as those of the armature 14 of the first embodiment.

  The limiter 215 is interposed between the armature 214 and the inner hub 16 in the power transmission path from the armature 214 to the inner hub 16. The limiter 215 is made of a nonmagnetic material. In this embodiment, it is formed of SUS304, but other austenitic stainless steels, copper alloys, aluminum alloys, and other metal materials can be used, and engineering plastics can also be used.

  The limiter 15 includes a main body portion 151 and a screw ring portion 252. The main body 151 is the same as that of the first embodiment. The screw ring portion 252 is a ring-shaped member. The limiter 15 has a shape in which a threaded ring portion 252 is connected to the armature 214 side of the outer peripheral portion of the main body portion 151.

  On the inner peripheral surface of the screw ring portion 252, a screw thread is provided over the entire periphery to form a female screw 255. In addition, an annular groove 256 having a C-shaped cross-section is provided at a corner formed between the main body 151 and the threaded ring part 252 so as to go around the threaded ring part 252.

  The female screw 255 of the screw ring portion 252 is screwed with a male screw 246 provided on the outer peripheral surface of the armature 214, and the limiter 215 and the armature 214 are connected by this screwing. The inner surface 153 of the main body 151 is in close contact with the flat portion 142 of the armature 214.

  The threaded form of the female screw 255 and the male screw 246 is a right-handed screw, and the armature 214 is centered on the center line CL in the direction from the front surface to the back surface in FIG. When rotated, the armature 214 is moved relative to the left in FIG. 4, and the limiter 215 is moved relative to the right in FIG.

  Since the screw ring portion 252 is located outside the armature 214, the space formed between the outer peripheral surface of the armature 214 and the outer cylindrical portion 111 of the pulley 11 is narrowed by the screw ring portion 252.

  Next, the operation of the power transmission device 210 of this embodiment will be described.

  When the electromagnet 12 is in a non-energized state, the electromagnetic force of the electromagnet 12 is not generated. For this reason, the armature 214 is held at a position away from the end face portion 113 of the pulley 11 by a biasing force of the leaf spring 18.

  As a result, the rotational driving force from the engine 6 is only transmitted to the pulley 11 via the V-belt 7, and not transmitted to the armature 214, limiter 215, and inner hub 16, and only the pulley 11 runs idle on the ball bearing 17. To do. That is, the compressor 2 that is the drive target device is stopped.

  On the other hand, when the electromagnet 12 is energized, an electromagnetic force of the electromagnet 12 is generated. By the electromagnetic force, the armature 214 is attracted to the pulley 11 by being attracted to the end surface portion 113 side of the pulley 11 against the urging force of the leaf spring 18. As a result, the rotation of the pulley 11 is transmitted to the armature 214, and the driven rotary body 13 including the leaf spring 18, the limiter 15, and the inner hub 16 rotates.

  At this time, if the compressor 2 is not locked, the rotation of the inner hub 16 is transmitted to the rotating shaft 21 of the compressor 2. Note that this rotation direction is a direction in which the armature 214 is rotated in the direction from the front surface to the back surface around the center line CL in FIG. At this time, the limiter 215 is connected to the armature 214 and the inner hub 16 to mediate power transmission from the armature 214 to the inner hub 16.

  Thus, the compressor 2 operates by rotating the rotary shaft 21. That is, the rotational driving force output from the engine 6 is transmitted to the compressor 2 via the power transmission device 10, so that the compressor 2 operates.

On the other hand, when the compressor 2 is locked due to seizure or the like and the rotation shaft 21 stops and cannot rotate, the rotation of the inner hub 16 and the limiter 15 is blocked by the rotation shaft 21.
Accordingly, the torque acting between the limiter 215 and the armature 214 increases. When this torque becomes very large, the armature 214 rotates with respect to the limiter 215. By this rotation, an axial force is generated between the male screw 246 of the armature 214 and the female screw 255 of the limiter 215.

  This axial force acts as a force that pulls the limiter 215 (screwed ring portion 252) toward the armature 214 side. However, the inner surface 153 of the main body 151 of the limiter 215 is in close contact with the flat portion 142 of the armature 214, and is prevented from moving by the axial force. For this reason, tensile stress is applied between the main body 151 and the threaded ring portion 252. This tensile stress acts intensively on the annular groove 256 provided at the corner between the main body 151 and the threaded ring portion 252.

  When the tensile stress exceeds a predetermined value, the limiter 215 is broken starting from the annular groove 256, and the main body 151 and the threaded ring 252 are separated.

  A series of parts from the limiter 215 to the inner hub 16 are separated from the armature 214 by separating the main body 151 and the screw ring portion 252.

  Since the limiter 15 is made of a nonmagnetic material, the armature 214 is not likely to be caught by the armature 214 due to the electromagnetic force exerted on the armature 214 from the electromagnet 12. As a result, when the limiter 15 is broken, the possibility that the main body 151 is attracted to the armature 14 by the electromagnetic force and rotates together with the armature 14 is reduced.

  For this reason, although the rotation of the pulley 11 is transmitted to the armature 214, it is not transmitted to the rotating shaft 21, and the pulley 11, the armature 214 and the threaded ring portion 252 of the limiter 215 are idled on the rotating shaft 21. That is, transmission of the rotational driving force from the engine 6 to the compressor 2 is interrupted. Therefore, it is possible to prevent an excessive load from being applied to the drive source side due to the lock of the compressor 2 that is the drive target device.

  Since the screwed ring portion 252 and the armature 214 are kept screwed even after the limiter 215 is broken, the screwed ring portion 252 separated from the main body portion 151 is held by the armature 214 to prevent falling off. Is done. Further, the main body 151 of the limiter 215 is connected to the inner hub 16 via the leaf spring 18, and the inner hub 16 is connected to the rotating shaft 21, so that the part extending from the main body 151 to the inner hub 16 is prevented from falling off. .

  Since the force that damages the limiter 215 when the rotating shaft 21 cannot rotate is derived from the axial force that acts on the limiter 215 by the screwing of the limiter 215 and the armature 214, the armature 214 and the rotating shaft are simple in structure. The limiter 215 is surely broken when the torque acting between the first and second torques exceeds the limit value.

  In addition, the limiter 215 is provided with an annular groove 256 having a C-shaped cross section, and this annular groove 256 is the starting point of breakage, so that the torque acting between the armature 214 and the rotating shaft 21 is limited. When the value is exceeded, the limiter 215 is broken more quickly and reliably.

  The limiter 215 breaks and splits into the main body 151 and the screw ring portion 252, but the main body 151, the leaf spring 18, and the inner hub 16 are held by the rotating shaft 21. The screw ring portion 252 is screwed into and integrated with the armature 214, but the main body portion 151 and the leaf spring 18 serve as a cover to prevent the armature 214 and the screw ring portion 252 from falling off. This is because the armature 214 and the leaf spring 18 partially overlap in the axial direction CL, and the armature 214 and the main body 151 partially overlap in the axial direction CL. Therefore, it is possible to prevent the parts constituting the driven-side rotating body 13 from falling off without requiring additional parts such as a cover.

  As described above, according to the power transmission device 210 of the present embodiment, when the compressor 2 that is the device to be driven is locked due to seizure or the like, the rotational driving force is transmitted from the power transmission device 210 to the device to be driven. Since it shuts off promptly, it is prevented that an excessive load is applied to the drive source side due to the lock of the drive target device.

  Even if the limiter 215 is broken, the broken main body 151 and screw ring portion 252 are prevented from falling off, and the armature 214 and the inner hub 16 are also prevented from falling off. Therefore, it is possible to prevent the parts constituting the driven-side rotating body 13 from falling off without using a part such as a cover. Therefore, the physique can be made smaller than before. Further, since the number of parts can be reduced, the cost can be reduced.

  Further, a threaded ring portion 252 enters between the outer peripheral surface of the armature 214 and the outer cylindrical portion 111 of the pulley 11. That is, since the gap between the outer peripheral surface of the armature 214 and the outer cylindrical portion 111 is narrowed by the screw ring portion 252, dust and the like pass through the gap and the end surface portion 113 of the pulley 11 and the flat portion 141 of the armature 214. Can be prevented from entering during the period.

(Embodiment 3)
An example in which a damping material is disposed between an armature and a limiter will be described as Embodiment 3 with reference to FIG. In addition, since many parts are common with Embodiment 1, about these common parts, description is abbreviate | omitted using the same code | symbol.

  As in the first embodiment (see FIG. 1), the power transmission device 310 according to the present embodiment intermittently transmits the rotational driving force output from the engine 6 that is the drive source to the compressor 2 that is the drive target device. In this example, the apparatus is applied to the compressor 2 of the refrigeration cycle 1.

  FIG. 5 is a cross-sectional view of the upper half when the power transmission device 310 is cut along the axial direction of the rotary shaft 21 of the compressor 2. Note that the rotation axis direction AD, the radial direction RD, and the center line CL shown in FIG. 5 have the same meaning as in the first embodiment.

  As shown in FIG. 5, an attenuation plate 320 made of an attenuation material is disposed between the armature 14 and the limiter 15, and is sandwiched between the armature 14 and the limiter 15. As a damping material for forming the damping plate 320, an elastic material such as a damping steel plate, rubber or synthetic resin can be used. In this embodiment, a damping steel plate is used.

  Since the damping plate 320 is sandwiched between the armature 14 and the limiter 15, when the armature 14 is attracted by the electromagnetic force of the electromagnet 12 to connect the driven rotary body 13 to the pulley 11, or the electromagnet 12 is turned off. The shock that occurs when the lever is released can be alleviated, and the sound that is generated at that time is also quieter.

  Further, as is apparent from the configuration shown in FIG. 5, the power transmission device 310 of the present embodiment operates in the same manner as in the first embodiment, and has the same effects as in the first embodiment.

(Embodiment 4)
An example of obtaining a dustproof and dripproof effect by extending the threaded ring portion 252 described in the second embodiment will be described as a fourth embodiment with reference to FIG. In addition, since many parts are common with Embodiment 1 or 2, about these common parts, the same code | symbol is used and description is abbreviate | omitted.

  As in the first embodiment (see FIG. 1), the power transmission device 410 according to the present embodiment intermittently transmits the rotational driving force output from the engine 6 that is the drive source to the compressor 2 that is the drive target device. In this example, the apparatus is applied to the compressor 2 of the refrigeration cycle 1.

  FIG. 6 is a cross-sectional view of the upper half when the power transmission device 410 is cut along the axial direction of the rotary shaft 21 of the compressor 2. Note that the rotation axis direction AD, the radial direction RD, and the center line CL shown in FIG. 6 have the same meaning as in the first embodiment.

  As shown in FIG. 6, in the power transmission device 410 of the present embodiment, the number of V groove portions 114 of the pulley 411 is reduced from that of the pulley 11 of the first to third embodiments. A concave groove 412 having a semicircular cross-sectional shape is provided in a connecting portion between the outer slope of the edge portion 411a located on the armature 214 side and the end surface portion 113.

  Further, the front end portion 252a of the threaded ring portion 252 extends toward the pulley 411 side, passes through the extended surface of the flat portion 141 and the extended surface of the surface of the end surface portion 113, and enters the inside of the concave groove 412. . However, the tip 252a does not contact the inner surface of the concave groove 412.

  As described above, the tip end portion 252a of the screw ring portion 252 enters the inside of the concave groove 412 and covers the peripheral edge portion of the end surface portion 113. Therefore, the dust is formed in the gap between the flat portion 141 and the end surface portion 113. And water droplets can be prevented from entering. That is, it has a dustproof and dripproof effect that prevents dust and water droplets from entering between the pulley 411 and the armature 214.

  Further, as is apparent from the configuration shown in FIG. 6, the power transmission device 410 of the present embodiment operates in the same manner as in the second embodiment and has the same effects as in the second embodiment.

(Other embodiments)
In addition, this invention is not limited to above-described embodiment, In the range described in the claim, it can change suitably. Further, the above embodiments are not irrelevant to each other, and can be combined as appropriate unless the combination is clearly impossible. In each of the above-described embodiments, the elements constituting the embodiment are not necessarily essential unless explicitly stated as essential and clearly considered essential in principle. Further, in each of the above embodiments, when numerical values such as the number, numerical value, quantity, range, etc. of the constituent elements of the embodiment are mentioned, it is clearly limited to a specific number when clearly indicated as essential and in principle. The number is not limited to the specific number except for the case. In particular, when a plurality of values are exemplified for a certain amount, it is also possible to adopt a value between the plurality of values unless specifically stated otherwise and in principle impossible. . Further, in each of the above embodiments, when referring to the shape, positional relationship, etc. of the component, etc., the shape, unless otherwise specified and in principle limited to a specific shape, positional relationship, etc. It is not limited to the positional relationship or the like. The present invention also allows the following modifications to the above embodiments. In addition, the following modifications can select application and non-application to the said embodiment each independently. In other words, any combination of the following modifications can be applied to the above-described embodiment.

(Modification 1)
In the third embodiment, an example in which an attenuation plate 320 made of an attenuation material is sandwiched between the armature 14 and the limiter 15 in a configuration in which the armature and the limiter are screwed on the inner peripheral side of the armature as in the first embodiment. In the configuration in which the armature 214 and the limiter 215 are screwed on the outer peripheral side of the armature 214 as in the second and fourth embodiments, a damping material may be sandwiched between the armature 214 and the limiter 215. it can. Even if the damping material is applied to the same configuration as in the second and fourth embodiments, the same impact mitigation and noise reduction effects as in the third embodiment can be obtained.

(Modification 2)
In the first and third embodiments, the main body 151 of the limiter 15 is an annular plate member.
If the screw ring portion 152 is a circular ring shape or a cylindrical shape, the main body portion 151 does not have to be annular, and the outer shape may be a polygon, for example. Moreover, the shape extended in the petal shape from the screwing ring part 152 may be sufficient. In the case of Embodiments 2 and 4, as long as the screw ring portion 252 is a circular ring shape or a cylindrical shape, the main body portion 151 does not need to be annular.

(Summary)
According to the first aspect shown in part or all of each of the above embodiments, the driven-side rotating body includes an armature that is attracted to the driving-side rotating body by electromagnetic force, an inner hub that is coupled to the rotating shaft, And a limiter interposed between the armature and the inner hub. The limiter is made of a non-magnetic material and is connected to the armature and the inner hub to mediate power transmission from the armature to the inner hub. The limiter breaks when the rotating shaft stops due to the lock, and the breakage of the limiter releases the armature.

  According to the second aspect, the limiter and the armature are screwed together. When the rotating shaft stops due to the lock, the limiter and the armature rotate relative to each other, and the axial force resulting from the screwing is exerted on the limiter. As a result, the limiter breaks and the power transmission from the armature to the inner hub is interrupted.

  By adopting such a configuration, the limiter can be reliably damaged when the rotating shaft is stopped by the lock.

  Moreover, according to the 3rd viewpoint, the limiter is screwing together with the armature in the inner peripheral part of the armature which is an annular plate member. Moreover, according to the 4th viewpoint, the limiter is screwing with the armature in the outer peripheral part of the armature which is a cyclic | annular board member.

  According to the fifth aspect, the limiter body faces the surface opposite to the surface facing the armature electromagnet, and the damping material is sandwiched between the limiter body and the armature. ing.

  By adopting such a configuration, it is possible to reduce the impact sound generated when the armature is attracted by the electromagnetic force of the electromagnet to connect the driven side rotating body to the driving side rotating body or when the connection is released.

2 Compressor (Drive target device)
10, 210, 310, 410 Power transmission device 11 Pulley 12 Electromagnet 13 Driven side rotating body 14, 214 Armature 15, 215 Limiter 151 Main body 152, 252 Threaded ring 320 Damping plate (damping material)

Claims (5)

A power transmission device (10, 210, 310, 410) for transmitting the rotational driving force output from the driving source (6) to the driving target device (2),
A driving side rotating body (11) that rotates by a rotational driving force output from the driving source;
A driven-side rotator (13) that rotates together with the rotation shaft (21) of the device to be driven by being connected to the drive-side rotator;
An electromagnet (12) for generating an electromagnetic force for coupling the driven-side rotator to the drive-side rotator,
The driven-side rotating body is interposed between the armature (14) attracted to the driving-side rotating body side by the electromagnetic force, an inner hub (16) connected to the rotating shaft, and the armature and the inner hub. The limiter is made of a non-magnetic material, and is connected to the armature and the inner hub to mediate power transmission from the armature to the inner hub,
The power transmission device according to claim 1, wherein the limiter is damaged when the rotating shaft is stopped by locking, and the connection with the armature is released due to the damage. The limiter and the armature are screwed together,
When the rotating shaft stops due to locking, the limiter and the armature rotate relative to each other, and at that time, the axial force derived from the screwing is exerted on the limiter and the limiter is damaged, and the armature is transferred to the inner hub. The power transmission device according to claim 1, wherein the power transmission is cut off.   The power transmission device according to claim 2, wherein the limiter is screwed to the armature at an inner periphery (145) of the armature, which is an annular plate member.   The power transmission device according to claim 2, wherein the limiter is screwed to the armature at an outer peripheral portion (144) of the armature that is an annular plate member.   The limiter body 151 faces the surface of the armature opposite to the surface facing the electromagnet, and a damping material 320 is sandwiched between the limiter body and the armature. The power transmission device according to any one of claims 1 to 4, wherein the power transmission device is provided.

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