JP2011231789A - Electromagnetic clutch for compressor and compressor integrated with the clutch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic clutch for a compressor, and a compressor, in which generation of drawing force in a drive shaft side of the compressor is prevented, a pressing force of an armature sufficient for high torque transmission to a rotor can be reliably obtained, and a small size, lightweight and power-saving electromagnetic coil can be achieved.SOLUTION: The electromagnetic clutch for a compressor includes a rotor connected to a power supply side, an armature connected to a compressor drive shaft side, an electromagnetic coil sucking the armature to the rotor, and an amplifying means for a pressing force of the armature to the rotor. To constitute the pressing force amplifying means, the rotor includes first and second rotor side friction plates disposed to oppose to each other through a gap determined by the shape of an elastic material that deforms in accordance with the pressing force. The armature includes a first and a second armature side friction plates to be in contact with the first and the second rotor side friction plates, and also includes a friction plate gap increasing mechanism for mechanically increasing the gap between the first and the second armature side friction plates in the axial direction accompanying the power transmission.

Description

  The present invention relates to an electromagnetic clutch and a compressor for a compressor, and more particularly to an electromagnetic clutch and a compressor for a compressor that are small and can achieve high transmission torque and power saving.

  In a compressor electromagnetic clutch, for example, a compressor used in a vehicle air conditioner, in order to control the transmission of power from the power source side to the compressor drive shaft side, an electromagnetic is applied to the power input side of the compressor. A clutch is often incorporated. This electromagnetic clutch generally includes a rotor connected to the power source side, an armature connected to the compressor drive shaft side, and a friction plate of both members that generates a magnetic force and attracts the armature to the rotor by the magnetic force. And an electromagnetic coil that enables power transmission between them. This electromagnetic clutch requires an electromagnetic coil having a high magnetomotive force in order to ensure a high torque required for the compressor. In order to ensure a high magnetomotive force, it is usually necessary to expand the coil space or reduce the coil electrical resistance. For this reason, electromagnetic clutches capable of transmitting high torque usually tend to be large in coil size or large in power consumption.

  The torque T of the electromagnetic clutch can be expressed as T = μPr. Here, μ is a coefficient of friction between the friction plates, P is a pressing force of the friction plate due to an electromagnetic adsorption force, and r is a radius of the friction plate. That is, the transmission torque can be improved by increasing any one of μ, P, and r. So far, as means for increasing P, proposals have been made to change the shape of the leaf spring of the armature or increase the pressing force of the armature against the rotor by adding a cam (for example, Patent Document 1).

JP 7-332394 A

  However, when the pressing force is changed by changing the shape of the leaf spring of the armature, a sufficient pressing force enhancement effect cannot be obtained due to the strength of the spring material. In addition, the mechanical pushing force augmentation structure by adding a cam can greatly increase the pushing force of the armature on the rotor and greatly increase the transmission torque, but the cam can amplify the pushing force of the armature on the rotor. Since the reaction force is received on the side connected to the drive shaft of the compressor, a reaction force equivalent to the amplified pressing force is applied as a pulling force on the drive shaft side of the compressor. There is concern about compressor damage due to pull-out force.

  Accordingly, an object of the present invention is to focus on the fact that the transmission torque can be significantly increased by mechanically amplifying the pressing force of the armature against the rotor, and at the same time, driving the compressor that has become a problem. The generation of pull-out force on the shaft side can be prevented, and the pressing force against the armature rotor sufficient for high torque transmission can be reliably obtained with a simple and small mechanism without causing problems. An object of the present invention is to provide a structure of an electromagnetic clutch for a compressor and a compressor incorporating the same, which can surely achieve power saving as well as reduction in size and weight.

  In order to solve the above problems, an electromagnetic clutch for a compressor according to the present invention includes a rotor coupled to a power source side via a power transmission mechanism, an armature coupled to a compressor drive shaft side, a magnetic force And an electromagnetic coil for adhering the armature to the rotor by the magnetic force to enable power transmission between both members, and a pressing force of the armature against the rotor to increase the power transmission capability. In an electromagnetic clutch for a compressor having a pressing force amplifying means for amplifying, in order to constitute the pressing force amplifying means, the rotor is a gap determined by the shape of an elastic body that deforms according to the magnitude of the pressing force. A first rotor-side friction plate and a second rotor-side friction plate disposed opposite to each other, and the armature is disposed in the gap And a first armature side friction plate capable of contacting the first rotor side friction plate and a second armature side friction plate capable of contacting the second rotor side friction plate. Accordingly, there is provided a mechanism for increasing the distance between the friction plates, which mechanically increases the distance between the first armature side friction plate and the second armature side friction plate in the axial direction.

  In such an electromagnetic clutch for a compressor according to the present invention, the rotor has a first rotor-side friction plate and a first rotor-side friction plate arranged opposite to each other with a gap determined by the shape of the elastic body that deforms according to the magnitude of the pressing force. 1st and 2nd armature side which has two rotor side friction plates and can contact between these 1st and 2nd rotor side friction plates between these 1st and 2nd rotor side friction plates A friction plate is disposed, and the distance between the first and second armature side friction plates is mechanically increased in the axial direction along with power transmission by the friction plate distance increasing mechanism. By increasing the distance between the friction plates, the first and second armature side friction plates are brought into contact with and pressed against the first and second rotor side friction plates, respectively, and the first rotor side friction plate and the first armature Power is transmitted by two sets of friction plates, a side friction plate, a second rotor side friction plate, and a second armature side friction plate. Therefore, the transmission power is greatly increased as compared with a conventional electromagnetic clutch that basically transmits power by a set of friction plates. The two sets of friction plates are in contact with each other with the first rotor side friction plate and the second rotor side disposed opposite each other with a gap determined by the shape of the elastic body deforming according to the magnitude of the pressing force. In other words, in the range of the rotor having the first rotor-side friction plate and the second rotor-side friction plate, the first armature-side friction plate first Since the direction of the pressing force against the rotor-side friction plate and the direction of the pressing force of the second armature-side friction plate against the second rotor-side friction plate are completely opposite to each other, these both pressing forces cancel out in the rotor. Will be. As a result, the generation of the pulling force on the compressor drive shaft, which was a problem with the conventional pressing force increasing mechanism that mechanically amplifies the pressing force of the armature side friction plate in the power transmission by a pair of friction plates Is efficiently prevented, and the concern about compressor damage associated with the generation of the pulling force is completely eliminated. The size of the electromagnetic coil that generates a magnetomotive force for attracting the first armature side friction plate to the first rotor side friction plate is reduced by greatly increasing the transmission power and preventing the generation of the pulling force. Thus, an electromagnetic coil with low power consumption is sufficient, and the electromagnetic coil can be reduced in size, weight, and power consumption can be reduced. Furthermore, since the first or second rotor side friction plate can move in the axial direction within a deformable range of the elastic body, the pressing force of the armature against the rotor can be absorbed by the elastic body.

  In the above-described electromagnetic clutch for a compressor according to the present invention, the elastic body is provided so as to be able to contact the surface of the first or second rotor side friction plate on the side opposite to the armature, and the first or second rotor side. It is preferable that the friction plate is configured to be deformed by receiving the pressing force from the armature side. The first rotor-side friction plate and the second rotor-side friction plate according to the axial length when the elastic body configured in this manner is deformed so as to generate an elastic restoring force having a magnitude that balances the pressing force. Since the size of the gap is determined, the magnitude of the pressing force can be controlled based on the elastic force characteristics of the elastic body, and the clutch torque can be controlled.

  In such an electromagnetic clutch for a compressor, it is preferable that the elastic body is a disc spring. By providing a disc spring so as to be able to contact the surface of the first or second rotor side friction plate on the side opposite to the armature, the gap between the first and second rotor side friction plates is slightly changed while the pressing force is reduced. It is possible to appropriately control the size.

  In the electromagnetic clutch for a compressor according to the present invention, the power transmission mechanism includes a pulley and a belt, and the magnitude of the elastic force generated against the pressing force due to deformation of the elastic body is from the power source to the rotor. It is preferable that the power is limited so that it does not rise above the value of the pressing force that causes slippage between the pulley and the belt during power transmission. When the elastic force of the elastic body is limited to the value of the pressing force or less, slippage occurs between the pulley and the belt even when the compressor is locked and the rotation of the compressor drive shaft is stopped. Therefore, since slip occurs between the rotor side friction plate and the armature side friction plate, it is possible to effectively prevent the belt from being damaged.

  The electromagnetic clutch for a compressor according to the present invention preferably includes friction surface heat generation detecting means for detecting heat generated between the first rotor side friction plate and the first armature side friction plate. The friction surface heat generation detecting means can be constituted by a thermal fuse provided in the vicinity of the electromagnetic coil, for example. By providing such frictional surface heat generation detection means, even when slippage occurs between the rotor side friction plate and the armature side friction plate when the compressor is locked, the heat generated on the friction surface is detected and the electromagnetic clutch is energized. It is possible to take measures to avoid failure such as blocking In particular, when the elastic force of the elastic body is limited to the above-described upper limit value or less, the energization to the electromagnetic clutch can be reliably interrupted while preventing the belt from being damaged.

  In the electromagnetic clutch for a compressor according to the present invention, the mechanism for increasing the distance between the friction plates is based on a relative twist between the first armature-side friction plate and the second armature-side friction plate accompanying power transmission. It can be composed of a mechanism that mechanically converts to directional displacement. That is, when the first armature-side friction plate is attracted to the first rotor-side friction plate by the excitation of the electromagnetic coil, power (torque) transmission is started. At this time, the power transmission side member is compressed. In the armature connected to the machine drive shaft side, relative torsion occurs between the first armature side friction plate and the second armature side friction plate. This relative twist is mechanically converted into an axial displacement in a direction that increases the distance between the first armature side friction plate and the second armature side friction plate by the friction plate distance increasing mechanism. The two armature side friction plates are pressed against the second rotor side friction plate immediately after being attracted by the electromagnetic force, and the power transmission state by the two sets of friction plates is automatically achieved.

  Further, as shown in an embodiment described later, such a friction plate distance increasing mechanism is engaged with the first armature side friction plate and the second armature side friction plate, and between the two friction plates. Further, a plurality of cams provided so as to be deformable in the direction in which the distance between the friction plates is increased and the direction in which the distance between the friction plates is reduced can be constituted by a plurality of mechanisms arranged in the circumferential direction of the friction plate. These cams are deformed in a direction that increases the distance between the two friction plates when power is transmitted, and are deformed in a direction that decreases the distance between the two friction plates when power transmission is interrupted.

  The friction plate distance increasing mechanism having such a cam is, for example, capable of elastically deforming a plurality of cams in a direction to increase the distance between the two friction plates, and the plurality of cams increasing the distance between the two friction plates. It can be composed of a mechanism provided with cam deformation assisting means that can be elastically restored in the shrinking direction. This cam deformation assisting means can be configured as a mechanism using rubber elasticity and elastic restoring force, or a mechanism using a spring incorporated therein and using the elasticity and elastic restoring force of the incorporated spring.

  The cam preferably includes a cam stroke limiting mechanism that limits a distance between the first armature-side friction plate and the second armature-side friction plate within a predetermined range. For example, when the mechanism for increasing the distance between the friction plates is a mechanism that mechanically converts the relative torsion into an axial displacement through rolling of a ball or a cylindrical body held in a predetermined space, By providing a pocket in the space to cancel the rise of the cam when the ball or cylinder falls into the interior, it is possible to limit the variation in the distance between the first and second armature side friction plates within a predetermined range. It becomes.

  The electromagnetic clutch for a compressor according to the present invention preferably includes a twist limiting mechanism for limiting the relative twist within a predetermined range. For example, by providing a simple twist limiting mechanism in which a protrusion obtained by partially extending the first armature side friction plate in the axial direction is provided and the protrusion is inserted into a hole provided in the second armature side friction plate. The relative twist can be limited within the clearance between the protrusion and the hole, and as a result, the variation in the distance between the first and second armature side friction plates can be limited within a predetermined range.

  Further, in the electromagnetic clutch for a compressor according to the present invention, the connection state between the armature side and the rotor side can be changed according to the magnitude of the required transmission power. That is, when the required transmission power is small, power transmission is performed by a set of friction plates of the first rotor side friction plate and the first armature side friction plate located on the electromagnetic coil side (that is, the conventional general Power transmission system in an electromagnetic clutch), when the required transmission power is large, the first rotor-side friction plate, the first armature-side friction plate, the second rotor-side friction plate, and the second armature-side friction plate It is also possible to perform power transmission (that is, a power transmission system unique to the present invention) by the two friction plates. In this way, it is possible to efficiently reduce the size and weight of the electromagnetic coil and reduce power consumption when high torque is transmitted, and to ensure quick operation for torque transmission when transmitting low torque. Become.

  Such an electromagnetic clutch for a compressor according to the present invention is particularly suitable when incorporated in a variable capacity compressor. In variable displacement compressors, the required drive torque varies greatly depending on the compression capacity required at that time, but by using the compressor electromagnetic clutch according to the present invention, from low torque transmission to high torque transmission. Stable power transmission performance can be obtained over the entire range.

  The compressor incorporating the compressor electromagnetic clutch according to the present invention is particularly suitable for use in a vehicle air conditioner. By using the electromagnetic clutch for a compressor according to the present invention, it is possible to reduce the size and weight of the electromagnetic clutch unit by reducing the coil size and the weight, thereby reducing the size and weight of the electromagnetic clutch built-in compressor as a whole. As a result, it is possible to improve the mountability to the vehicle and contribute to the improvement of the fuel consumption of the vehicle. By reducing the power consumption, it is possible to contribute to the further improvement of the fuel consumption of the vehicle and to the equipment that requires other electric power. It is possible to provide a margin for the supplied power.

  Thus, according to the electromagnetic clutch for a compressor and a compressor incorporating the same according to the present invention, two sets of friction plates are arranged between the rotor and the armature, and the first and second rotor side friction plates are arranged. The armature side of each of the two sets of friction plates is made to oppose each other with a gap determined by the shape of the elastic body deforming according to the magnitude of the pressing force, and to increase the distance between the friction plates of the armature mechanically. The pressing force of the friction plate against the rotor side friction plate can be increased, and the pressing force of the armature side friction plate acting on the rotor side friction plate acting respectively in the two sets of friction plate portions can be offset within the range of the rotor. Therefore, the pulling force applied to the drive shaft side of the compressor, which has been a problem with conventional mechanisms, while achieving a significant increase in transmission power by mechanical amplification of the pressing force It is possible to prevent the occurrence, can have a large power transmission performance desired in the electromagnetic clutch in small, low magnetomotive force of the electromagnetic coil. And since an electromagnetic coil can be reduced in size, the electromagnetic clutch part and by extension, the whole compressor can be reduced in size and weight, and power consumption can be reduced. Furthermore, since the first or second rotor side friction plate can move in the axial direction within a deformable range of the elastic body, the pressing force of the armature against the rotor can be absorbed by the elastic body.

It is the longitudinal cross-sectional view (A) and front view (B) of the electromagnetic clutch for compressors which concern on one embodiment of this invention. It is a fragmentary longitudinal cross-sectional view of the electromagnetic clutch for compressors of FIG. It is the longitudinal cross-sectional view (A) and front view (B) of the 1st armature side friction board used for the electromagnetic clutch for compressors of FIG. It is the longitudinal cross-sectional view (A) and front view (B) of the 2nd armature side friction board used for the electromagnetic clutch for compressors of FIG. FIG. 2 is an enlarged partial plan view of a cam and its peripheral portion of the compressor electromagnetic clutch of FIG. 1. It is a schematic block diagram for demonstrating operation | movement of the site | part shown in FIG. It is a schematic block diagram for demonstrating operation | movement of the cam shown in FIG. It is a schematic block diagram which shows the example of the distance increase mechanism between the friction plates of the electromagnetic clutch for compressors concerning the embodiment different from FIG. FIG. 6 is a schematic configuration diagram illustrating an example of an inter-friction plate distance increasing mechanism of an electromagnetic clutch for a compressor according to another embodiment different from FIG. 5. FIG. 6 is a schematic configuration diagram illustrating an example of an inter-friction plate distance increasing mechanism of an electromagnetic clutch for a compressor according to another embodiment different from FIG. 5.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
1 to 7 show an electromagnetic clutch for a compressor according to an embodiment of the present invention. In FIG. 1, a compressor electromagnetic clutch 1 includes a rotor 2 connected to a power source (for example, a vehicle engine, not shown) through a power transmission mechanism including a pulley (not shown) and a belt 52. An armature 4 connected to the compressor drive shaft 3 side, and an electromagnetic coil 5 that generates a magnetic force and attracts the armature 4 to the rotor 2 by the magnetic force to enable power transmission between the two members. Yes. The electromagnetic clutch 1 for the compressor mechanically amplifies the pressing force of the armature 4 (the friction plate of the armature 4) against the rotor 2 (the friction plate of the rotor 2) in order to increase the power transmission capability. Means 6 are provided.

  The pressing force amplifying means 6 is configured as follows. 2, the rotor 2 includes a first rotor-side friction plate 7 and a second rotor-side friction plate 8 that are arranged to face each other with a gap G that varies according to a change in the shape of the disc spring 51. In this embodiment, the second rotor-side friction plate 8 varies with respect to the first rotor-side friction plate 7 according to the shape change of the disc spring 51 via the fixing bolt 9. It is fixed with a gap G. The armature 4 is disposed within the range of the gap G, and the first armature-side friction plate 10 and the second rotor-side friction plate 8 that can come into contact with the first rotor-side friction plate 7. It has the 2nd armature side friction board 11 which can contact | abut. In addition, the armature 4 uses a distance D (for example, a distance between the outer surfaces) between the first armature side friction plate 10 and the second armature side friction plate 11 as the power is transmitted between the rotor 2 and the armature 4. The friction plate distance increasing mechanism 13 is mechanically increased in the direction (compressor shaft direction 12). In this embodiment, on the second rotor-side friction plate 8 disposed opposite to the second armature-side friction plate 11, improvement of power transmission performance and prevention of interference between the friction plates when power transmission is interrupted (for example, In order to prevent seizure during half-clutch), a friction liner 14 is provided. The friction liner 14 may be provided on the second armature side friction plate 11 side.

  In addition, a thermal fuse 55 is installed in the vicinity of the electromagnetic coil 5 to detect heat generated on the friction surface when slippage occurs between the rotor side friction plate and the armature side friction plate, and to the electromagnetic clutch 1. The power can be cut off.

  3 and 4 are a longitudinal sectional view (A) and a front view (B) of the armature side friction plates 10 and 11, respectively. In the second armature side friction plate 11 shown in FIG. 4, a protrusion 53 having a shape partially extending from a portion extending in the axial direction is provided in three adjacent locations in the circumferential direction of the friction plate so as to form a central angle of 120 °. Are formed along. In the first armature side friction plate 10 of FIG. 3, protrusion insertion holes 54 are formed at three positions corresponding to the protrusions 53. As shown in FIGS. 1 and 2, the first armature side friction plate 10 and the second armature side friction plate 11 are arranged in parallel, and the protrusion 53 on the friction plate 11 is connected to the protrusion insertion hole 54 on the friction plate 10. Thus, the relative twist between the friction plates 10 and 11 is prevented from increasing beyond the clearance between the protrusion 53 and the protrusion insertion hole 54.

  The friction plate distance increasing mechanism 13 mechanically converts relative torsion in the rotational direction between the first armature side friction plate 10 and the second armature side friction plate 11 due to power transmission into displacement in the axial direction 12. It consists of a mechanism to convert to. More specifically, as shown in FIGS. 5 and 6, the first armature side friction plate 10 and the second armature side friction plate 11 are engaged with each other, and both the friction plates 10 and 11 are both engaged. A cam 15 is provided so as to be deformable in a direction in which a distance D (for example, a distance between outer surfaces) between the friction plates 10 and 11 is increased and a direction in which the distance D is reduced. The inclination angle of the cam 15 with respect to the first armature side friction plate 10 and the second armature side friction plate 11 changes from θ1 to θ2 with the relative twist (the inclination angle changes in the direction in which the cam 15 rises). ), The distance D between the friction plates 10 and 11 is increased. A plurality of cams 15 are arranged at a predetermined interval in the circumferential direction of the friction plate, and these cams 15 are deformed in a direction to increase the distance D between the friction plates 10 and 11 during power transmission, and both frictions when power transmission is cut off. The distance D between the plates 10 and 11 is deformed in a decreasing direction. As described above, since the relative twist between the friction plates 10 and 11 is limited within the clearance between the protrusion 53 and the protrusion insertion hole 54, the variation of the distance D is also limited within a predetermined range. Between the cams 15, the plurality of cams 15 can be elastically deformed in a direction that increases the distance D between the friction plates 10, 11, and the plurality of cams 15 have the distance D between the friction plates 10, 11. Rubber 16 as cam deformation assisting means that can be elastically restored in the shrinking direction is provided between adjacent cams 15, and the rubber 16 is provided with a slit 17 for weight reduction.

  The second armature side friction plate 11 is formed of an annular member having an L-shaped cross section, and is connected to a hub 19 fastened and fixed to an end portion of the drive shaft 3 via an elastically deformable annular rubber member 18. ing. Therefore, power for rotational drive is transmitted from the second armature side friction plate 11 to the compressor drive shaft 3 via the rubber member 18 and the hub 19.

  In the compressor electromagnetic clutch 1 configured as described above, the pressing force amplifying means 6 having the friction plate distance increasing mechanism 13 allows the power transmission capability to be as follows, although the electromagnetic coil 5 is small and light. Will be increased. In principle, as shown in FIG. 7, the inclination angle θ of the cam 15 interposed between the first and second armature side friction plates 10 and 11 and engaged with both the friction plates 10 and 11 is determined by the power. Changes from the initial θ1 to θ2 (shown in FIG. 6) due to the relative displacement (relative twist) between the friction plates 10 and 11 due to the load on the compressor (compressor drive shaft) side accompanying (torque) transmission. Accordingly, the pressing force of the first and second armature-side friction plates 10 and 11 against the first and second rotor-side friction plates 7 and 8 is amplified, and the pressing forces in the opposite directions are increased. It cancels out within the range of the rotor 2. By this cancellation, generation of the shaft pulling force acting on the compressor drive shaft side, which is a problem in the conventional structure, is prevented.

At this time, the inclination angle θ of the cam 15 needs to be set to be less than 90 degrees at the maximum. Further, it is necessary that the relationship of torque by electromagnetic adsorption force + amplified torque> compressor load torque be established. In other words,
Fd · μ · r + Fb · μ · r · 2> Fa · r
It is necessary to establish the relationship. here,
Fa: Compressor load Fb: Pushing force (amplification)
Fd: electromagnetic clutch attractive force r: cam arrangement radius μ: friction coefficient. The cam compression force Fc is Fa / cos θ, and the pressing force Fb is Fa × tan θ. By the way, if the armature plate spring angle in the conventional structure is aimed to increase the transmission force only in one direction, the boosting effect can be obtained only about 10% at most, but it can be canceled as described above. In a structure that increases the pressing force in both directions, a much larger transmission force amplification effect can be obtained.

  The first and second rotor side friction plates 7 of the first and second armature side friction plates 10 and 11 via the cam 15 by the pressing force amplifying means 6 having such a friction plate distance increasing mechanism 13. The first rotor side friction plate 7 and the first armature side friction plate 10 and the second rotor side friction plate 8 and the second armature side friction in a state where the pressing force is amplified by the amplification of the pressing force against 8 The power transmission is performed by the two sets of friction plates of the plate 11, and the transmission power is greatly increased compared to the conventional electromagnetic clutch in which the power transmission is basically performed by one set of friction plates. Further, the abutment between these two sets of friction plates, in other words, the pressing force of the first and second armature side friction plates 10 and 11 against the first and second rotor side friction plates 7 and 8 is as follows: Since they act as forces in opposite directions, they are canceled within the range of the rotor 2, and the conventional pressing that mechanically amplifies the pressing force of the armature side friction plate in the power transmission by a pair of friction plates Generation of the pulling force applied to the compressor drive shaft, which has been a problem with the force increasing mechanism, is efficiently prevented, and the concern about the compressor damage accompanying the generation of the pulling force is completely eliminated. Further, by increasing the pressing force of each friction plate 10, 11 through the cam 15, the electromagnetic coil 5 generates a magnetomotive force for attracting the first armature side friction plate 10 to the first rotor side friction plate 7. The size is small, and the electromagnetic coil 5 with low power consumption is sufficient. Therefore, the electromagnetic coil 5 can be reduced in size, weight, and power consumption. In the case where the required transmission power is small, the first rotor is solely based on the electromagnetic adsorption force of the electromagnetic coil 5 without exhibiting the effect of amplifying the pressing force of the friction plates 10 and 11 via the cam 15. Power can be transmitted by pressure-bonding the first armature side friction plate 10 to the side friction plate 7.

  Further, in the above embodiment, since the friction liner 14 is interposed between the second armature side friction plate 11 and the second rotor side friction plate 8 disposed opposite thereto, for example, at the time of half clutch It is possible to prevent burn-in and the like, thereby preventing the occurrence of defects in this portion and improving durability.

  Further, in the above embodiment, since the rubber 16 is provided as the cam deformation assisting means, an elastic restoring function for returning the cam 15 to the original tilt angle state can be secured by the rubber 16, and the cam 15 is sealed by the rubber 16. By doing so, it becomes possible to take a dust-proof measure and a rust-proof measure for the cam 15. Further, by forming a slit 17 having an appropriate size in the rubber 16, the weight can be reduced.

  The specific structure of the pressing force amplifying means 6 having the friction plate distance increasing mechanism 13 is not limited to the structure using the cam 15 in the above embodiment, and various structures can be adopted. For example, as shown in FIG. 8, one cam member 21 which is arranged on one armature side friction plate side which can be twisted relative to each other, or one armature side friction plate itself is integrally formed, and the other Between the other cam member 22 which is disposed on the side of the armature side friction plate or the other armature side friction plate itself is integrally formed by concave portions 23 and 24 having a spherical cross section or an arc shape. A structure in which a space 26 that can hold the ball or the cylindrical body 25 is formed, and a compression spring 27 that allows relative torsion between the cam members 21 and 22 and elastic recovery thereof can be employed. In this structure, when the stationary state (power cut-off state) shown in FIG. 8 (A) shifts to the operation state (power transmission state) shown in FIG. 8 (B), relative torsion between the cam members 21 and 22 occurs. Along with this, the ball or the cylindrical body 25 in the space 26 rolls along the concave surfaces of the spherical concave portions 23 and 24, and accordingly, the distance between the cam members 21 and 22 is the direction of the arrow in FIG. Is increased to 28. As a result, the pressing force of the armature-side friction plate against the rotor-side friction plate in the opposite direction is amplified. At this time, the spring 27 is compressed by the relative torsion between the cam members 21 and 22, but the relative positional relationship between the cam members 21 and 22 is determined by the elastic restoring force of the compressed spring 27 when the power transmission is interrupted. It is naturally returned to the original positional relationship.

  In the form shown in FIG. 9, one cam member 31 arranged on one armature side friction plate side that can be relatively twisted with each other, or formed integrally with one armature side friction plate itself, and the other Cam mechanism with tapered surfaces 33 and 34 which are arranged on the armature side friction plate side or engaged with and slidably contact each other with the other cam member 32 which is integrally formed with the other armature side friction plate. 35 is formed, and a structure is provided in which a compression spring 36 that allows relative torsion between the cam members 31 and 32 and elastic recovery thereof is interposed. Even in such a structure, when the stationary state (power cutoff state) shown in FIG. 9A shifts to the operation state (power transmission state) shown in FIG. As the twisting occurs, the cam mechanism 35 acts in a direction that increases the distance between the cam members 21 and 22 in the direction indicated by the arrow 37 in FIG. 9B, whereby the armature side friction plate in the opposite direction is on the rotor side. The pressing force against the friction plate is amplified. At this time, the spring 36 is compressed by the relative torsion between the cam members 31 and 32, but the relative positional relationship between the cam members 31 and 32 is determined by the elastic restoring force of the compressed spring 36 when the power transmission is interrupted. It will naturally return to the original positional relationship.

  Further, as shown in FIG. 10, one cam member 41 which is arranged on one armature side friction plate side which can be relatively twisted with each other, or one armature side friction plate itself is integrally formed, Concave portions 43, 44, 49 having a spherical or arcuate cross section with the other cam member 42 disposed on the other armature side friction plate side or the other armature side friction plate itself. Thus, a space 46 capable of holding the ball or the cylindrical body 45 is formed in the interior, and a structure including a compression spring 47 that enables relative torsion between the cam members 41 and 42 and elastic recovery thereof can be employed. In this structure, as in the structure shown in FIG. 8, when the transition is made from the initial state (power cut-off state) shown in FIG. 10 (A) to the cam start-up time (power transmission state 1) shown in FIG. 10 (B). The ball or the cylindrical body 45 of the space 46 rolls along the concave surfaces of the spherical concave portions 43 and 44 with the relative twist between the cam members 41 and 42, and accordingly, both the cam members 41 and 42. The distance between the cam members 41 and 42 increases when the distance between the cam members 41 and 42 increases to a predetermined value or more. Transition to the transmission state 2), the ball or cylinder 45 falls into the recess 49. As a result, the pressing force of the armature side friction plate in the opposite direction against the rotor side friction plate is amplified, and when a predetermined set load is exceeded, the ball or the cylindrical body 45 is formed as a recess pocket. The cam rise can be canceled by retracting to 49. Similarly to the structure shown in FIG. 8, when the power transmission is interrupted, the relative positional relationship between the cam members 41 and 42 is naturally returned to the original positional relationship by the elastic restoring force of the spring 47.

  The electromagnetic clutch for a compressor according to the present invention can be applied to any compressor using a friction plate electromagnetic clutch, and is particularly suitable for a variable capacity compressor and further a compressor for a vehicle air conditioner.

DESCRIPTION OF SYMBOLS 1 Compressor electromagnetic clutch 2 Rotor 3 Compressor drive shaft 4 Armature 5 Electromagnetic coil 6 Pushing force amplifying means 7 First rotor side friction plate 8 Second rotor side friction plate 9 Fixing bolt 10 First armature side friction plate 11 Second armature side friction plate 12 Compressor axial direction 13 Friction plate distance increasing mechanism 14 Friction liner 15 Cam 16 Rubber 17 as cam deformation assisting means Slit 18 Annular rubber member 19 Hubs 21, 22, 31, 32, 41 , 42 Cam member 23, 24, 43, 44, 49 Recess 25, 45 Ball or cylindrical body 26, 46 Space 27, 36, 47 Compression springs 28, 37, 48 Distance increasing direction between both cam members 33, 34 Tapered surface 35 cam mechanism 51 disc spring 52 belt 53 protrusion 54 protrusion insertion hole 55 thermal fuse

Claims (9)

  A rotor connected to the power source side via a power transmission mechanism, an armature connected to the compressor drive shaft side, a magnetic force is generated, and the armature is attracted to the rotor by the magnetic force between the two members. In the electromagnetic clutch for a compressor, comprising: an electromagnetic coil that enables power transmission of the motor; and a pressing force amplifying means that mechanically amplifies the pressing force of the armature against the rotor to increase power transmission capability. In order to constitute the force amplifying means, the rotor includes a first rotor side friction plate and a second rotor side that are arranged to face each other with a gap determined by the shape of an elastic body that deforms according to the magnitude of the pressing force. A first armature having a friction plate, the armature being disposed in the gap and capable of contacting the first rotor side friction plate; A second armature-side friction plate capable of contacting the friction plate and the second rotor-side friction plate, and the first armature-side friction plate and the second armature-side friction plate according to power transmission. An electromagnetic clutch for a compressor, comprising a friction plate distance increasing mechanism for mechanically increasing the distance in an axial direction.   The elastic body is provided so as to be able to contact the surface of the first or second rotor-side friction plate on the side opposite to the armature, and the first or second rotor-side friction plate receives the pressing force from the armature side. The electromagnetic clutch for a compressor according to claim 1, wherein the electromagnetic clutch is deformed.   The electromagnetic clutch for a compressor according to claim 2, wherein the elastic body is a disc spring.   The power transmission mechanism comprises a pulley and a belt, and the magnitude of the elastic force generated against the pressing force due to the deformation of the elastic body is between the pulley and the belt when the power is transmitted from the power source to the rotor. The electromagnetic clutch for a compressor according to any one of claims 1 to 3, wherein the electromagnetic clutch is restricted so as not to rise above a value of a pressing force that causes slippage.   The friction plate distance increasing mechanism includes a mechanism that mechanically converts relative torsion between the first armature side friction plate and the second armature side friction plate due to power transmission into axial displacement. Item 5. An electromagnetic clutch for a compressor according to any one of Items 1 to 4.   The mechanism for increasing the distance between the friction plates engages with the first armature-side friction plate and the second armature-side friction plate, and reduces the distance between the friction plates in the direction of increasing the distance between the friction plates. A plurality of cams disposed in the circumferential direction of the friction plate, and the cam is a distance between the first armature side friction plate and the second armature side friction plate. The electromagnetic clutch for a compressor according to claim 5, further comprising a cam stroke limiting mechanism for limiting the pressure within a predetermined range.   The electromagnetic clutch for a compressor according to claim 5 or 6, further comprising a twist limiting mechanism that limits the relative twist within a predetermined range.   A variable capacity compressor in which the electromagnetic clutch for a compressor according to claim 1 is incorporated.   The compressor used for the vehicle air conditioner in which the electromagnetic clutch for compressors in any one of Claims 1-7 is integrated.

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