WO2014112327A1 - Electromagnetic clutch - Google Patents

Abstract

An electromagnetic coil (51) forms a magnetic circuit (M) for generating an attractive magnetic force for linking a pulley (30) and an armature (40) by causing a magnetic flux to pass multiple times through a boundary between the pulley (30) and the armature (40). A predetermined number of magnetic poles are formed between the pulley (30) and the armature (40), the predetermined number being six or more and representing the number of times the magnetic flux passes through the boundary between the pulley (30) and the armature (40) in the magnetic circuit (M).

Description

Electromagnetic clutch Cross-reference of related applications

This disclosure is based on Japanese Patent Application No. 2013-004616 filed on January 15, 2013, and the contents thereof are disclosed in this specification.

This disclosure relates to an electromagnetic clutch.

Conventionally, as shown in Patent Document 1, an electromagnetic clutch using an aluminum wire (hereinafter referred to as an aluminum wire) has been proposed as a wire constituting an electromagnetic coil that generates an attractive magnetic force for connecting a pulley and an armature. Yes.

The electromagnetic clutch using an aluminum wire can first reduce the weight of the electromagnetic coil itself (copper specific gravity: 8.96), compared to an electromagnetic clutch using a conventional copper wire (hereinafter referred to as a copper wire). Aluminum specific gravity: 2.7) Secondly, it is possible to reduce the manufacturing cost of the electromagnetic coil by manufacturing the copper with a relatively inexpensive aluminum material.

However, an electromagnetic clutch using an aluminum wire has a problem that the size of the electromagnetic clutch becomes larger than that of an electromagnetic clutch using a copper wire, and the weight of the electromagnetic clutch increases accordingly.

Here, it is also possible to use aluminum wire while maintaining the same physique (clutch diameter, clutch shaft length) as the electromagnetic clutch using copper wire. However, at this time, the resistance value of the aluminum wire is larger than the resistance value of the copper wire. For this reason, the negative overcurrent of the electromagnetic coil using a copper wire and the electromagnetic coil using the aluminum wire of the same wire diameter as a copper wire using the vehicle power supply (generally output voltage is 12V) of the same output voltage When the negative overcurrent is measured, the load current of the electromagnetic coil using the aluminum wire becomes smaller than the load current of the electromagnetic coil using the copper wire.

As a result, the attractive force (that is, the attractive force for connecting the pulley and the armature) in the electromagnetic clutch expressed by the load current × the number of turns (= the number of amperes, that is, the AT value) is reduced. Along with this, the transmission torque of the electromagnetic clutch decreases, so that a desired transmission force cannot be obtained.

On the other hand, in order to obtain a desired transmission torque when an electromagnetic clutch is configured using an aluminum wire so as to have the same physique as an electromagnetic clutch using a copper wire, the wire diameter of the aluminum wire is set to be the same as that of the copper wire. This can be dealt with by increasing the load current by forming the electromagnetic coil with a larger diameter.

However, an increase in the load current causes an increase in power consumption (W = VI) when the electromagnetic clutch is ON, a reduction in vehicle fuel consumption, and a decrease in the performance of the electromagnetic clutch due to an increase in the temperature of the electromagnetic coil. Is inevitable.

For this reason, in order to cope with these contradictions of aluminum wire, while increasing the wire diameter of the aluminum wire and increasing the size of the electromagnetic coil as described above, the number of times of wire winding is increased and the electromagnetic wire using the aluminum wire is used. It is necessary to design the AT value of the clutch to be equivalent to the AT value of the electromagnetic coil using a copper wire.

However, in this case, as the size of the electromagnetic coil increases, the iron coil housing that houses the electromagnetic coil becomes larger. This leads to an increase in the size of the iron rotor (pulley) that covers the coil housing from the outside. As a result, there has been a problem that the entire electromagnetic clutch is increased in size and, consequently, increased in weight.

The following shows the causal relationship that increases the size of the electromagnetic clutch when the copper wire of the conventional clutch is replaced with aluminum wire.

First, the resistance value r _Cu per unit length of the resistance value r _AI and copper wire per unit length of the aluminum wire, in the following relationship.

Second, the AT value (= current × number of coil turns) representing the attractive force of the electromagnetic coil has the following relationship.

Here, A is the load current, T is the number of coil turns, V is the power supply voltage, R is the coil resistance, r is the resistance per unit length of the wire, and Dm is the nominal diameter of the electromagnetic coil.

Third, the electrical resistance value of the wire is inversely proportional to the square of the wire diameter.

From the above relationship, in order for the aluminum wire to have the same resistance value per unit length as the copper wire, the wire diameter of the aluminum wire needs to be 1.3 times the wire diameter of the copper wire. .

Therefore, in order to obtain the same AT value as the electromagnetic clutch using the aluminum wire, the aluminum wire having a wire diameter 1.3 times that of the copper wire was used, and the copper wire was used. It is necessary to ensure the same number of turns (T) as the electromagnetic coil.

For this reason, the winding space for accommodating the electromagnetic coil in the electromagnetic clutch using the aluminum wire needs to be 1.3 times larger than the winding space of the electromagnetic clutch using the copper wire.

Therefore, the axial dimension (that is, the axial length) of the electromagnetic coil of the four-pole electromagnetic clutch using aluminum wire is larger than the axial dimension of the electromagnetic coil of the four-pole electromagnetic clutch using copper wire.

With the increase in the size of such an electromagnetic coil, an iron stator housing that stores an electromagnetic coil to constitute a magnetic circuit of the electromagnetic coil, and a rotating shaft that is disposed outside the iron stator housing while ensuring a clearance with respect to the iron stator housing. On the other hand, the pulley supported rotatably is also enlarged. As a result, the physique of the electromagnetic clutch is increased.

As the physique of such an electromagnetic clutch increases, the weight increases. Thereby, not only the mountability of the vehicle but also the fuel efficiency is significantly affected.

Below, the result of comparing the conventional 4-pole electromagnetic clutch using copper wire and the 4-pole electromagnetic clutch using aluminum wire under the same transmission torque performance is shown.

Hereinafter, for convenience, a 4-pole electromagnetic clutch using copper wire is referred to as a copper wire electromagnetic clutch, and a 4-pole electromagnetic clutch using aluminum wire is referred to as an aluminum wire electromagnetic clutch.

15 (a) and 15 (b), Cu represents a copper wire electromagnetic clutch, AL (1) represents an aluminum wire electromagnetic clutch having the same physique as a copper wire electromagnetic clutch, and AL (2) These show the aluminum wire electromagnetic clutch which consumes the same power consumption as a copper wire electromagnetic clutch.

As shown in Cu and AL (1) in FIG. 15A, when the copper wire electromagnetic clutch and the aluminum wire electromagnetic clutch of the same size are compared, the power consumption of the copper wire electromagnetic clutch is 100%. Then, the percentage of power consumption of the aluminum wire electromagnetic clutch is 160%.

As shown in Cu and AL (1) of FIG. 15 (b), when a copper wire electromagnetic clutch and an aluminum wire electromagnetic clutch of the same physique are compared, the weight of the copper wire electromagnetic clutch is assumed to be 100%. The percentage of the weight of the aluminum wire electromagnetic clutch is 90%.

As shown in Cu and AL (2) of FIG. 15 (b), when the copper wire electromagnetic clutch and the aluminum wire electromagnetic clutch having the same power consumption are compared, the weight of the copper wire electromagnetic clutch is 100%. Then, the percentage of the weight of the aluminum wire electromagnetic clutch becomes 105%.

Thus, when an aluminum wire electromagnetic clutch having the same physique as the copper wire electromagnetic clutch is configured, the power consumption of the aluminum wire electromagnetic clutch is significantly larger than the power consumption of the copper wire electromagnetic clutch. If an aluminum wire electromagnetic clutch having the same power consumption as that of the copper wire electromagnetic clutch is configured, it becomes heavier than the aluminum wire electromagnetic clutch and the copper wire electromagnetic clutch. Thus, it can be seen that the weight reduction of the product, which was the aim of adopting aluminum as the wire material, cannot be achieved.

JP 2009-243678 A (corresponding to US 2009/0243773 A1)

In view of the above points, it is an object of the present disclosure to reduce the weight of an electromagnetic clutch in which an electromagnetic coil wire is formed of an aluminum material.

In order to achieve the above object, the present disclosure provides an electromagnetic clutch including a driving side rotating body, a driven side rotating body, and an electromagnetic coil. The drive-side rotator rotates about a rotation center line by a rotational drive force from a drive source. When connected to the drive-side rotator, the driven-side rotator is rotated about the rotation center line by the rotational driving force transmitted from the drive-side rotator. The electromagnetic coil is made of an aluminum material and has a wound wire. The electromagnetic coil generates an attractive magnetic force for connecting the driving side rotating body and the driven side rotating body by allowing magnetic flux to pass through the boundary between the driving side rotating body and the driven side rotating body a plurality of times. The generated magnetic circuit is formed. A predetermined number of magnetic poles are formed between the driving side rotating body and the driven side rotating body, and the predetermined number is 6 or more, and the number of times the magnetic flux passes through the boundary in the magnetic circuit. Show.

FIG. 1 is a diagram illustrating an overall configuration of a refrigeration cycle apparatus according to a first embodiment to which an electromagnetic clutch of the present disclosure is applied. FIG. 2 is a cross-sectional view of the electromagnetic clutch of the first embodiment. 3 is a cross-sectional view taken along line III-III in FIG. 4 is an end view of the single pulley in FIG. 2 viewed from one end side in the axial direction of the rotation shaft of the compressor. FIG. 5 is a partial perspective view of a part of the pulley as viewed from one end in the axial direction. FIG. 6 is an end view of the armature alone viewed from one end in the axial direction. 7A is a partial cross-sectional view showing a state where the pulley and the armature shown in FIG. 2 are separated from each other, and FIG. 7B is a diagram showing a state where the pulley and the armature shown in FIG. 2 are connected. FIG. FIG. 8 is a diagram showing the relationship between the number of poles, the ratio of magnetic fluxes, and the ratio of pole areas in the electromagnetic clutch. FIG. 9A is a schematic diagram showing the dimensional relationship of the four-pole clutch in the comparative example, and FIG. 9B is a schematic diagram showing the dimensional relationship of the six-pole clutch of the first embodiment. FIG. 10 is a diagram illustrating the attractive force and magnetomotive force of the electromagnetic clutch. FIG. 11 is a diagram showing magnetic flux densities of 1 pole to 6 poles. FIG. 12A is a diagram showing a comparison of the amount of winding used in a 4-pole clutch and a 6-pole clutch, and FIG. 12B is a diagram showing a comparison of weights in a 4-pole clutch and a 6-pole clutch. It is. FIG. 13 is a cross-sectional view of the electromagnetic clutch according to the second embodiment of the present disclosure. FIG. 14A is a partial perspective view of a pulley according to a modified example of the present disclosure, and FIG. 14B is a partial end view of an armature according to the modified example of the present disclosure. FIG. 15A is a diagram showing a comparison of power consumption between an electromagnetic clutch using a copper wire and an electromagnetic clutch using an aluminum wire, and FIG. 15B uses an electromagnetic clutch using a copper wire and an aluminum wire. It is a figure which shows the comparison of the weight with an electromagnetic clutch.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are given the same reference numerals in the drawings in order to simplify the description.

(First embodiment)
FIG. 1 is an overall configuration diagram of a refrigeration cycle apparatus 1 of a vehicle air conditioner to which an electromagnetic clutch of the present embodiment is applied.

The refrigeration cycle apparatus 1 has a compressor 2, a radiator 3, an expansion valve 4, and an evaporator 5 connected thereto. The compressor 2 sucks and compresses the refrigerant. The radiator 3 radiates the refrigerant discharged from the compressor 2. The expansion valve 4 decompresses and expands the refrigerant flowing out of the radiator 3. The evaporator 5 evaporates the refrigerant depressurized by the expansion valve 4 and exhibits an endothermic effect.

Compressor 2 is installed in the engine room of the vehicle. The compressor 2 sucks the refrigerant from the evaporator 5 and compresses it by driving the compression mechanism by the rotational driving force applied from the engine 10 as the driving source for driving through the electromagnetic clutch 20.

As the compression mechanism of the compressor 2, either a fixed displacement type compression mechanism with a fixed discharge capacity or a variable capacity type compression mechanism configured to be able to adjust the discharge capacity by an external control signal is adopted. May be.

The electromagnetic clutch 20 of the present embodiment is a pulley-integrated electromagnetic clutch connected to the compressor 2. The electromagnetic clutch 20 transmits the rotational driving force of the engine 10 given from the engine side pulley 11 via the V belt 12 to the compressor 2. The engine-side pulley 11 is connected to the rotational drive shaft of the engine 10.

The electromagnetic clutch 20 includes a pulley 30 and an armature 40. The pulley 30 constitutes a driving-side rotating body that rotates by a rotational driving force applied from the engine 10 via the V-belt 12. The armature 40 constitutes a driven side rotating body connected to the rotating shaft 2 a of the compressor 2. The electromagnetic clutch 20 is configured to intermittently transmit the rotational driving force from the engine 10 to the compressor 2 by connecting or separating the pulley 30 and the armature 40.

That is, when the electromagnetic clutch 20 connects the pulley 30 and the armature 40, the rotational driving force of the engine 10 is transmitted to the compressor 2 and the refrigeration cycle apparatus 1 operates. On the other hand, when the electromagnetic clutch 20 separates the pulley 30 and the armature 40, the rotational driving force of the engine 10 is not transmitted to the compressor 2, and the refrigeration cycle apparatus 1 does not operate.

Next, the detailed configuration of the electromagnetic clutch 20 of the present embodiment will be described with reference to FIG.

FIG. 2 is an axial sectional view of the electromagnetic clutch 20. This axial sectional view is a sectional view including the rotation center line O of the rotation shaft 2 a of the compressor 2 in the electromagnetic clutch 20 and along the rotation center line O. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 2 illustrates a state where the pulley 30 and the armature 40 are separated. 4 is an end view of the pulley 30 alone viewed from one end side in the axial direction of the rotation center line O of the rotary shaft 2a of the compressor 2, and FIG. 5 is a partial perspective view of a part of the pulley 30 viewed from one end side in the axial direction. FIG. 6 is an end view of the armature 40 alone viewed from one end side in the axial direction.

As shown in FIG. 2, the electromagnetic clutch 20 includes a stator 50 together with a pulley 30 and an armature 40.

First, the pulley 30 has an outer cylindrical portion 31, an inner cylindrical portion 32, and an end surface portion (wall portion extending in the radial direction) 33.

The outer cylindrical portion 31 is formed in a cylindrical shape centered on the rotation center line O of the rotation shaft 2 a of the compressor 2. The outer cylindrical portion 31 is formed of a magnetic material (for example, iron). A V groove (specifically, a poly V groove) on which the V belt 12 is hung is formed on the outer peripheral side of the outer cylindrical portion 31.

The inner cylindrical part 32 is disposed on the inner peripheral side of the outer cylindrical part 31 and is formed in a cylindrical shape centered on the rotation center line O of the rotary shaft 2 a of the compressor 2. The inner cylindrical portion 32 is made of a magnetic material (for example, iron).

The outer race of the ball bearing 34 is fixed to the inner peripheral side of the inner cylindrical portion 32. The ball bearing 34 fixes the pulley 30 to the housing 2c forming the outer shell of the compressor 2 so as to be rotatable about the rotation center line O of the rotation shaft 2a. Therefore, the inner race of the ball bearing 34 is fixed to the housing 2c of the compressor 2 by a snap ring or the like. The inner race of the ball bearing 34 is disposed on the outer side in the radial direction with respect to the housing boss portion 2 b provided on the housing 2 c of the compressor 2. The housing boss portion 2 b is formed in a cylindrical shape centered on the rotation center line O of the rotation shaft 2 a of the compressor 2.

The end surface portion 33 is formed between the other end side in the axial direction of the outer cylindrical portion 31 and the other end side in the axial direction of the inner cylindrical portion 32.

The end face portion 33 is formed in a ring shape centering on the rotation center line O of the rotation shaft 2a. Specifically, the end surface portion 33 includes ring members 60, 61, 62, and 63 as shown in FIG.

The ring members 60, 61, 62, and 63 are concentric with the rotation center line O of the rotation shaft 2a, that is, are formed in a ring shape centering on the rotation center line O. The ring members 60, 61, 62, 63 are arranged offset from each other in the radial direction of the rotating shaft 2a.

The ring member 60 of this embodiment is disposed on the inner peripheral side with respect to the ring member 61. The ring member 61 is disposed on the inner peripheral side with respect to the ring member 62. The ring member 62 is disposed on the inner peripheral side with respect to the ring member 63. The ring members 60, 61, 62, and 63 are each formed of a magnetic material (for example, iron).

A nonmagnetic portion 67 made of a nonmagnetic metal material is disposed between the ring members 60 and 61. The nonmagnetic portion 67 is formed in a ring shape centering on the rotation center line O of the rotation shaft 2 a and connects between the ring members 60 and 61.

Between the ring members 61 and 62, a nonmagnetic portion 66 made of a nonmagnetic metal material is disposed. The nonmagnetic portion 66 is formed in a ring shape centered on the rotation center line O of the rotation shaft 2 a and connects between the ring members 61 and 62.

Between the ring members 62 and 63, a nonmagnetic portion 65 made of a nonmagnetic metal material is disposed. The nonmagnetic portion 65 is formed in a ring shape centering on the rotation center line O of the rotation shaft 2 a and connects between the ring members 62 and 63.

As a material constituting the nonmagnetic portions 67, 66, 65 of the present embodiment, SUS304 (stainless steel) or a nonmagnetic metal material such as copper is used.

In this embodiment, the pulley 30 is integrally formed. For this reason, the outer cylindrical part 31 and the ring member 63 of the end surface part 33 are connected. The ring member 60 of the end surface portion 33 and the inner cylindrical portion 32 are connected. The outer cylindrical portion 31, the ring members 60, 61, 62, 63 of the end surface portion 33, and the inner cylindrical portion 32 constitute a magnetic circuit M as will be described later.

Also, the other side surface of the end surface portion 33 forms a friction surface that comes into contact with the armature 40 when the pulley 30 and the armature 40 are connected. Therefore, in the present embodiment, the friction member 35 for increasing the friction coefficient of the end surface portion 33 is disposed on the surface side of the nonmagnetic portion 65 of the end surface portion 33. The friction member 35 is formed in a ring shape centering on the rotation center line O of the rotating shaft 2a. The friction member 35 is made of a nonmagnetic material. Specifically, a material obtained by solidifying alumina with a resin or a sintered material of metal powder (for example, aluminum powder) can be used.

The armature 40 is disposed on the other end side in the axial direction with respect to the end surface portion 33 of the pulley 30. Specifically, the armature 40 is a disk-shaped member that extends in a direction perpendicular to the rotation shaft 2a and has a through hole that penetrates the front and back in the axial direction at the center. The rotation center line of the armature 40 coincides with the rotation center line O of the rotation shaft 2a.

The armature 40 is composed of ring members 80, 81, 82 as shown in FIG. The ring members 80, 81, and 82 are concentric with the rotation center line O of the rotation shaft 2a, that is, are formed in a ring shape centering on the rotation center line O. The ring members 80, 81, 82 are arranged offset from each other in the radial direction of the rotating shaft 2a.

The ring member 80 of this embodiment is disposed on the inner peripheral side with respect to the ring member 81. The ring member 81 is disposed on the inner peripheral side with respect to the ring member 82. The ring members 80, 81, 82 are each formed of a magnetic material (for example, iron).

Between the ring members 80 and 81, a nonmagnetic portion 83 made of a nonmagnetic metal material is disposed. The nonmagnetic portion 83 is formed in a ring shape centered on the rotation center line O of the rotation shaft 2a. The nonmagnetic portion 83 connects between the ring members 80 and 81.

Between the ring members 81 and 82, a nonmagnetic portion 84 made of a nonmagnetic metal material is disposed. The nonmagnetic portion 84 is formed in a ring shape centered on the rotation center line O of the rotation shaft 2a. The nonmagnetic portion 84 connects between the ring members 81 and 82.

SUS304 (stainless steel) or copper nonmagnetic metal material is used as the material constituting the nonmagnetic portions 83 and 84 of the present embodiment.

Here, the flat surface on one end side of the armature 40 faces the end surface portion 33 of the pulley 30. The plane on one end side of the armature 40 forms a friction surface that comes into contact with the pulley 30 when the pulley 30 and the armature 40 are connected.

Furthermore, a substantially disc-shaped outer hub 42 is connected to the plane on the other end side of the armature 40 by a rivet 41.

The outer hub 42 constitutes a connecting member for connecting the armature 40 and the rotating shaft 2a of the compressor 2 together with an inner hub 43 described later. The outer hub 42 and the inner hub 43 respectively have cylindrical portions 42a and 43a extending in the rotation axis direction. The outer peripheral surface of the cylindrical portion 42a of the outer hub 42 and the outer peripheral surface of the cylindrical portion 43a of the inner hub 43 are provided on the outer hub 42 and the inner hub 43, respectively. A cylindrical rubber 45 which is an elastic member is vulcanized and bonded. As a material of the rubber 45, EPDM (ethylene / propylene / diene terpolymer rubber) or the like can be employed.

Furthermore, the inner hub 43 is fixed by being tightened by a bolt 44 in a screw hole provided in the rotary shaft 2 a of the compressor 2. Note that a fastening means such as a spline (serration) or a key groove may be used to fix the inner hub 43 and the rotary shaft 2a of the compressor 2.

As a result, the armature 40, the outer hub 42, the rubber 45, the inner hub 43, and the rotating shaft 2a of the compressor 2 are connected. When the pulley 30 and the armature 40 are connected, the armature 40, the outer hub 42, the rubber 45, the inner The hub 43 and the rotary shaft 2 a of the compressor 2 rotate together with the pulley 30.

Further, the rubber 45 applies an elastic force to the outer hub 42 in a direction in which the armature 40 is separated from the pulley 30. In a state where the pulley 30 and the armature 40 are separated by this elastic force, a predetermined gap M1 (see FIG. 5) between one end face of the armature 40 connected to the outer hub 42 and the other end face of the pulley 30 is shown. 7) is formed.

The stator 50 is a stator assembly including an electromagnetic coil 51 and a stator housing 52.

The electromagnetic coil 51 is disposed between the outer cylindrical portion 31 and the inner cylindrical portion 32 of the pulley 30 and is formed in a ring shape centering on the rotation center line O of the rotating shaft 2a. The electromagnetic coil 51 of this embodiment is configured by winding a wire made of aluminum (hereinafter referred to as an aluminum wire) 51a around a resin spool in multiple rows and multiple layers. The electromagnetic coil 51 of the present embodiment is fixed to the stator housing 52 by fitting and fastening.

The stator housing 52 has an outer cylindrical portion 52a, an inner cylindrical portion 52b, and an end surface portion 52c.

The outer cylindrical portion 52 a is disposed between the electromagnetic coil 51 and the outer cylindrical portion 31 of the pulley 30. The outer cylindrical portion 52a is formed in a cylindrical shape centered on the rotation center line O of the rotation shaft 2a. The outer cylindrical part 52a forms a gap M2 (see FIG. 3) between the outer cylindrical part 52a and the outer cylindrical part 31 of the pulley 30.

The inner cylindrical portion 52 b is disposed between the electromagnetic coil 51 and the inner cylindrical portion 52 b of the pulley 30. The inner cylindrical portion 52b is formed in a cylindrical shape centered on the rotation center line O of the rotation shaft 2a.

The end surface portion 52 c is formed between one end side in the axial direction of the outer cylindrical portion 52 a and one end side in the axial direction of the inner cylindrical portion 32. The end surface portion 52c is formed in a ring shape centered on the rotation center line O of the rotation shaft 2a.

The outer cylindrical portion 52a, the inner cylindrical portion 52b, and the end surface portion 52c of the present embodiment are formed of a magnetic material (for example, iron).

The stator housing 52 of the present embodiment is fixed to the housing 2c of the compressor 2 by fixing means such as a snap ring 100. As a result, the electromagnetic coil 51 and the stator housing 52 are fixed to the housing 2c. A gap M <b> 3 (see FIG. 3) is provided between the inner cylindrical portion 52 b of the stator housing 52 and the inner cylindrical portion 32 of the pulley 30.

Further, the control device 6 in FIG. 1 controls energization to the electromagnetic coil 51 based on a control signal output from an air conditioner ECU (electronic control device).

Next, the operation of the electromagnetic clutch 20 of the present embodiment will be described with reference to FIGS. 7 (a) and 7 (b). FIG. 7A and FIG. 7B are explanatory views using a cross-sectional view of a portion indicated by VII in FIG.

First, when the control device 6 is not energizing the electromagnetic coil 51, a gap M1 is formed between the armature 40 and the pulley 30 by the elastic force of the rubber 45 as shown in FIG. Is done. That is, the electromagnetic clutch 20 is in an OFF state.

Next, the control device 6 starts energizing the electromagnetic coil 51. At this time, as shown by a thick chain line in FIG. 7B, the stator housing 52, the outer cylindrical portion 31, the end surface portion 33, the armature 40, the end surface portion 33, the armature 40, the end surface portion 33, the armature 40, the end surface portion 33, A magnetic circuit M through which magnetic flux passes through the inner cylindrical portion 32 and the stator housing 52 is formed.

Specifically, in the magnetic circuit M, the magnetic flux avoids the nonmagnetic portions 83 and 84 of the armature 40 and the nonmagnetic portions 65, 66 and 67 of the pulley 30 between the outer cylindrical portion 31 and the inner cylindrical portion 32. pass.

That is, in the magnetic circuit M, the magnetic flux passes between the outer cylindrical portion 31 and the inner cylindrical portion 32 through the ring members 80, 81, 82 of the armature 40 and the ring members 60, 61, 62, 63 of the pulley 30. For this reason, the boundary between the armature 40 and the pulley 30 passes six times.

Here, the magnetic force generated by the magnetic circuit M indicated by the thick chain line in FIG. 7B is an attractive magnetic force that connects the pulley 30 and the armature 40. For this reason, the pulley 30 and the armature 40 can be connected by the magnetic force generated from the magnetic circuit M. That is, the electromagnetic clutch 20 is turned on. For this reason, the rotational driving force from the engine 10 can be transmitted to the compressor 2 by the electromagnetic clutch 20.

Thereafter, the control device 6 ends energization of the electromagnetic coil 51. For this reason, the magnetic circuit M is not formed, and the state returns to the state of FIG. Thereby, a gap M <b> 1 is formed between the armature 40 and the pulley 30 by the elastic force of the rubber 45. Thereby, transmission of the rotational driving force from the engine 10 to the compressor 2 is stopped.

According to the present embodiment described above, the pulley 30 rotated by the rotational driving force from the engine 10, the armature 40 to which the rotational driving force is transmitted by being connected to the pulley 30, and the aluminum wire are wound. An electromagnetic coil 51 is formed, which forms a magnetic circuit M through which a magnetic flux passes a plurality of times through the boundary between the pulley 30 and the armature 40 and generates an attractive magnetic force for connecting the pulley 30 and the armature 40.

Here, the nonmagnetic portions 83 and 84 of the armature 40 and the nonmagnetic portions 65, 66, and 67 of the pulley 30 are offset in the radial direction of the rotating shaft 2a. Therefore, in the magnetic circuit M, the magnetic flux passes between the outer cylindrical portion 31 and the inner cylindrical portion 32 while avoiding the nonmagnetic portions 83 and 84 of the armature 40 and the nonmagnetic portions 65, 66 and 67 of the pulley 30. . Thereby, the boundary between the armature 40 and the pulley 30 is passed six times. In other words, six boundary portions through which the magnetic flux passes are provided between the armature 40 and the pulley 30 in the radial direction. These six boundary portions are the boundary portion B1 between the ring member 80 and the ring member 60, the boundary portion B2 between the ring member 80 and the ring member 61, the ring member 81 and the ring shown in FIG. A boundary B3 between the members 61, a boundary B4 between the ring member 81 and the ring member 62, a boundary B5 between the ring member 82 and the ring member 62, and between the ring member 82 and the ring member 63. And a boundary portion B6.

Here, the number of times the magnetic flux passing through the magnetic circuit M passes through the boundary between the pulley 30 and the armature 40 is the number of poles, and the magnetic flux passing through the magnetic circuit M passes through the boundary between the pulley 30 and the armature 40. The plane (boundaries B1 to B6) is defined as a magnetic pole. According to this definition, the number of magnetic poles of the magnetic circuit M of the present embodiment, that is, the number of poles becomes 6.

On the other hand, the number of poles of the magnetic circuit M of the electromagnetic clutch of Patent Document 1 is four. For this reason, the pole number of the magnetic circuit M of this embodiment is larger than the pole number of the magnetic circuit M of the electromagnetic clutch of patent document 1.

The table in FIG. 8 shows conditions for obtaining the same attractive force, that is, the same torque when the number of poles of the magnetic circuit M is changed from 4 poles to 6 poles. However, it is assumed that the inner and outer diameters (ie, the inner diameter and the outer diameter) of the friction surface between the armature 40 and the pulley 30 are the same regardless of whether the number of poles is four or six.

8 The table in FIG. 8 is based on the following equations (4) and (5).

The transmission torque T is represented by the product of the friction coefficient μ, the friction surface suction force F, and the friction surface effective average radius R. The attractive force F is expressed by the number of poles n, the amount of magnetic flux Φ, the magnetic permeability μ _{0 of} vacuum, and the pole area S.

Here, the friction surface effective average radius R is a radius on the friction surface between the armature 40 and the pulley 30. The transmission torque T is a transmission torque transmitted between the armature 40 and the pulley 30. μ is a friction coefficient of a friction surface between the armature 40 and the pulley 30. F is a suction force between the armature 40 and the pulley 30. R is a friction surface effective average radius. n is the number of poles, Φ is the amount of magnetic flux flowing through the magnetic circuit M, and μ ₀ is the permeability of vacuum. S is the polar area.
In this embodiment, the pole area is defined as an area per one of a plurality of poles.

Here, assuming that the pole area when the number of poles is 4 is S4 and the pole area when the number of poles is 6 is S6, the inner and outer diameters of the friction surface between the armature 40 and the pulley 30 are as follows. The same applies to the case where the number of poles is 4 and the number of poles is 6. For this reason, the ratio of S4 and S6 is 1 to 2/3. If the magnetic flux density passing through each pole is the same in the case where the number of poles is 4 and the case where the number of poles is 6, the ratio of the magnetic flux amount Φ passing through each pole is also the pole area S. It is the same as the ratio, and the ratio of Φ4 and Φ6 is 1 to 2/3. Let Φn be the amount of magnetic flux when the number of poles is n (≧ 4).

Here, the magnetic circuit M (see FIG. 9B) of the electromagnetic clutch having 6 poles (hereinafter referred to as 6-pole clutch) and the magnetism of the electromagnetic clutch having 4 poles (hereinafter referred to as 4-pole clutch). When the circuit Ma (see FIG. 9A) generates the same attractive magnetic force, the amount of magnetic flux flowing through the magnetic circuit M of the 6-pole clutch is 2 / of the amount of magnetic flux flowing through the magnetic circuit Ma of the 4-pole clutch. 3

Therefore, even if the cross-sectional area of the path through which the magnetic flux passes in the magnetic circuit M is 2/3, the magnetic flux density (the amount of magnetic flux per unit area) becomes the same as the magnetic flux density of the magnetic circuit M, and magnetic saturation occurs. There is nothing.

Accordingly, the plate thicknesses (t1 to t7) of the armature 40, the pulley 30 and the stator housing 52 constituting the magnetic circuit M are the same as the plates of the armature 40, the pulley 30 and the stator housing 52 constituting the magnetic circuit Ma. The thickness can be reduced to 2/3 of the thickness (T1 to T7). As a result, the armature 40, the pulley 30, and the stator housing 52 can be reduced in weight, and thus the electromagnetic clutch 20 can be reduced in weight. The plate thickness is a dimension in a direction orthogonal to the direction in which the magnetic flux flows.

Due to the above effects, the coil space (solid quadrilateral portion in the figure) constituting the electromagnetic coil 51 can be increased while reducing the weight and maintaining the physique of the electromagnetic clutch 20. Therefore, in order to obtain the same resistance value as that of the copper wire, it is possible to secure a coil space necessary for winding the aluminum wire, which must have a large wire diameter, the same number of times as the copper wire.

In addition to this, as described above, since the magnetic flux flowing through the magnetic circuit M is reduced, the magnetomotive force in the electromagnetic coil 51 necessary for maintaining the ON state of the electromagnetic clutch 20 can be reduced. For example, in order to obtain a certain predetermined torque (transmission torque), the magnetomotive force which was 680 AT in the 4-pole clutch becomes 410 AT (≈680 AT × 2/3) which is about 2/3 of 680 AT in the 6-pole clutch. .

Furthermore, since the coil space can be increased as described above, the wire diameter of the aluminum wire can be increased, or the number of turns of the aluminum wire can be increased. For this reason, the load current flowing through the electromagnetic coil can be increased, or the number of turns of the aluminum wire can be increased.

As described above, it is possible to secure the AT value necessary for obtaining a predetermined torque (transmission torque) without increasing the physique of the electromagnetic clutch 20 even when an aluminum wire is used by the 6-pole clutch. become.

Next, the results of magnetic field analysis of an actual 6-pole clutch will be described. In the six-pole clutch that has been subjected to the magnetic field analysis, the armature 40, the pulley 30, and the stator housing 52 are reduced in thickness so as to ensure a minimum necessary space for housing the electromagnetic coil 51 made of an aluminum coil. .

In FIG. 11, the vertical axis indicates the magnetic flux density, and the horizontal axis indicates one pole (1P in the figure), two poles (2P in the figure), three poles (3P in the figure), four poles (4P in the figure), 5 poles (5P in the figure) and 6 poles (6P in the figure) are shown. In FIG. 11, 1 pole to 6 poles indicate poles formed at the boundary between the pulley 30 and the armature 40 of the 6 pole clutch, and the larger the number, the closer to the outer peripheral side from the center side.

As can be seen from this magnetic field analysis, in the six-pole clutch, the magnetic circuit M is reduced in cross-sectional area by reducing the plate thickness of the armature 40, the pulley 30, and the stator housing 52. The magnetic flux density is less than the saturation magnetic flux density (≈2 Tesla) of the iron material, and it can be seen that magnetic flux leakage (= waste of power consumption) due to thinning does not occur. Of course, there is no decrease in the attractive force (AT value) related to the transmission torque performance. (All models had a friction surface outer diameter of 101 mm and an inner diameter of 52 mm.)
For reference, when the armature 40, the pulley 30 and the stator housing 52 are reduced in thickness by a four-pole clutch to reduce the cross-sectional area of the magnetic circuit M, the magnetic flux density of each magnetic pole becomes the saturation magnetic flux density of the iron material. As a result, the magnetism leaks to the surroundings, resulting in consumption of more power than necessary.

12A is a diagram showing a comparison of the amount of winding used for a 4-pole clutch using a copper wire as a coil material and a 6-pole clutch using an aluminum wire as a coil material according to the present disclosure. ) Is a four-pole clutch that uses copper wire as a coil material, and a six-pole clutch that uses aluminum wire as a coil material according to the present disclosure. It is a figure which shows a comparison. The physique (body diameter, shaft length) of the electromagnetic clutch is the same for both clutches.

As shown in FIGS. 12 (a) and 12 (b), the 6-pole clutch has an electromagnetic coil that has the effect of reducing the plate thickness of the armature 40, the pulley 30, and the stator housing 52 and the effect of using aluminum wires. 51, and the total weight of the pulley 30, the stator housing 52, and the electromagnetic coil 51 can be reduced.

In addition, the material cost of aluminum wire is generally lower than that of copper wire, and the amount of windings can be reduced according to the present disclosure, so the cost of the electromagnetic coil can be greatly reduced.

Securing the strength of the pulley 30 is raised as a contradiction when reducing the plate thickness of the armature 40, the pulley 30, and the stator housing 52 (that is, reducing the thickness).

The limit of the plate thickness on the magnetic performance is that the magnetic flux density of each pole (1-6 poles) mentioned above (Fig. 11) exceeds the saturation flux density (≈ 2 Tesla) of the iron material, and magnetic leakage occurs. Thickness. On the other hand, the pulley 30 obtains the rotational driving force from the engine-side pulley 11 (crank pulley) of the vehicle engine 10 via the V-belt 12, for example, but the tension of the V-belt 12 is always applied. Therefore, a plate thickness design is required in which deformation and fatigue failure do not occur during the service life due to the stress caused by this.

Here, since the tension of the V-belt 12 varies from vehicle to vehicle, the plate thickness at which any of the characteristics cannot be satisfied while comparing the strength limit due to the tension of the V-belt 12 and the magnetic saturation limit derived from the magnetic performance. Is the minimum thickness.

Based on the thickness of each part of the electromagnetic clutch currently on the market, the pulley 30 is thinned so that t1 / T1 is about 0.7 to 0.8 in FIGS. 9 (a) and 9 (b). By satisfying the requirements, both the magnetic performance and the strength against the belt tension of a general vehicle (except for vehicles with specially high belt tension) can be satisfied, and an aluminum coil can be used without increasing the size of the clutch. Although it can be used, it is not limited to this.

In the present embodiment, the non-magnetic portions 65, 66, and 67 of the pulley 30 are made of SUS304 (stainless steel) or a non-magnetic metal material such as copper in a ring shape. For this reason, the strength against the tension of the V-belt 12 can be secured and further magnetic leakage can be prevented.

(Second Embodiment)
In the first embodiment, the example in which the armature 40 and the pulley 30 are configured so that the number of poles of the magnetic circuit M is 6 has been described. Instead, in this embodiment, the number of poles of the magnetic circuit M is An example in which the armature 40 and the pulley 30 are configured to be 8 will be described.

FIG. 13 shows a partial cross-sectional view of the electromagnetic clutch 20 of the present embodiment.

The armature 40 of this embodiment is obtained by adding a ring member 85 and a nonmagnetic portion 86 to the armature 40 of the first embodiment. For this reason, the armature 40 of this embodiment is provided with the ring members 80, 81, 82, 85 and the nonmagnetic portions 83, 84, 86. The ring member 85 is made of a magnetic material and is formed in a ring shape centered on the rotation center line O of the rotation shaft 2a. The nonmagnetic portion 86 is made of a nonmagnetic material and is formed in a ring shape centering on the rotation center line O of the rotation shaft 2a.

The ring member 85 and the nonmagnetic part 86 are disposed between the nonmagnetic part 83 and the ring member 81. The ring member 85 is disposed between the nonmagnetic portions 83 and 86. The nonmagnetic portion 86 is disposed between the ring members 81 and 85.

The pulley 30 of the present embodiment is obtained by adding a ring member 64 and a nonmagnetic portion 69 to the end surface portion 33 of the pulley 30 of the first embodiment. For this reason, the end surface portion 33 of the pulley 30 of the present embodiment includes the ring members 60, 61, 62, 63, 64 and the nonmagnetic portions 65, 66, 67, 69.

The ring member 64 and the nonmagnetic part 69 are disposed between the ring member 61 and the nonmagnetic part 66. The ring member 64 is made of a magnetic material, and is formed in a ring shape centered on the rotation center line O of the rotation shaft 2a. The nonmagnetic portion 69 is formed in a ring shape centered on the rotation center line O of the rotation shaft 2a. The ring member 64 is disposed between the nonmagnetic portions 66 and 69. The nonmagnetic portion 69 is disposed between the ring members 61 and 64.

In the magnetic circuit M of the electromagnetic clutch 20 of the present embodiment configured as described above, the magnetic flux is generated between the non-magnetic portions 83, 84, 86 of the armature 40 and the pulley 30 between the outer cylindrical portion 31 and the inner cylindrical portion 32. It passes through the non-magnetic portions 65, 66, 67, 69.

That is, in the magnetic circuit M, the magnetic flux is between the outer cylindrical portion 31 and the inner cylindrical portion 32, and the ring members 80, 81, 82, 85 of the armature 40 and the ring members 60, 61, 62, 63, 64 of the pulley 30 Pass through. For this reason, the boundary between the armature 40 and the pulley 30 passes eight times. Therefore, the number of poles of the magnetic circuit M of this embodiment is 8.

According to the present embodiment described above, the number of poles of the magnetic circuit M of the present embodiment is larger than the number of poles of the magnetic circuit M of the first embodiment. Therefore, in the case where the magnetic circuit M of the present embodiment and the magnetic circuit M of the first embodiment generate the same attractive magnetic force, the magnetic circuit M flows in the present embodiment as compared with the first embodiment. Magnetic flux is reduced.

Therefore, the thickness of each of the armature 40, the pulley 30, and the stator housing 52 constituting the magnetic circuit M can be further reduced. For this reason, the electromagnetic clutch 20 can be further reduced in weight.

(Other embodiments)
In the first embodiment, an example in which the armature 40 and the pulley 30 are configured so that the number of poles of the magnetic circuit M is six will be described, and in the second embodiment, the number of poles of the magnetic circuit M is eight. Although the example which comprised the armature 40 and the pulley 30 so that it may become was demonstrated, it is not restricted to this, You may comprise the armature 40 and the pulley 30 so that the pole number of the magnetic circuit M may become ten or more.

That is, in the first and second embodiments described above, the example in which the electromagnetic clutch 20 in which the number of poles of the magnetic circuit M is 6 or 8 has been described has been described. If the electromagnetic clutch 20 is as described above, the electromagnetic clutch 20 in which the number of poles of the magnetic circuit M is 10 or more is also included in the scope of the present invention.

In order to implement the electromagnetic clutch 20 having 10 or more poles, the number of nonmagnetic portions of the armature 40 and the number of nonmagnetic portions of the pulley 30 are increased as compared with the case where the number of poles is 8. Good.

In the first embodiment, the example in which the ring-shaped member made of a nonmagnetic metal material is used as the nonmagnetic portions 65, 66, and 67 of the pulley 30 has been described, but instead, the nonmagnetic portion 65 is used. , 66 and 67 may be formed of a gap and a bridge portion, respectively.

For example, as shown in the modification of FIG. 14A, the nonmagnetic portion 65 of the pulley 30 is composed of a plurality of gaps 111 and a plurality of bridge portions 110. The plurality of gaps 111 are formed in an arc shape centered on the rotation center line O of the rotation shaft 2a. The plurality of bridge portions 110 are made of a nonmagnetic metal material (or a magnetic metal material) and connect the ring members 62 and 63. In the nonmagnetic portion 65, the plurality of gaps 111 and the plurality of bridge portions 110 are alternately arranged in the circumferential direction. Similarly to the nonmagnetic part 65, the nonmagnetic parts 66 and 67 are composed of a plurality of gaps 111 and a plurality of bridge parts 110.

Further, as shown in the modification of FIG. 14B, the non-magnetic portion 83 of the armature 40 is replaced with a plurality of gaps 211, similarly to the non-magnetic portions 65, 66, and 67 of the pulley 30 of FIG. You may comprise from the some bridge | bridging part 210. FIG. In the nonmagnetic portion 83 of the armature 40, the plurality of gaps 211 and the plurality of bridge portions 210 are alternately arranged in the circumferential direction. The plurality of bridge portions 210 constituting the nonmagnetic portion 83 are members that connect the ring members 80 and 81.

Similarly, the nonmagnetic portion 84 of the armature 40 may be composed of a plurality of gaps 211 and a plurality of bridge portions 210. In the nonmagnetic portion 84 of the armature 40, the plurality of gaps 211 and the plurality of bridge portions 210 are alternately arranged in the circumferential direction. The plurality of bridge portions 210 constituting the nonmagnetic portion 84 are members that connect between the ring members 81 and 82.

Similarly, the nonmagnetic portion 69 of the end surface portion 33 of the pulley 30 in the second embodiment may be constituted by a plurality of gaps and a plurality of bridge portions. Furthermore, you may comprise the nonmagnetic part 86 in the said 2nd Embodiment from several space | gap and several bridge | bridging part.

In the first and second embodiments, the electromagnetic clutch 20 that connects the armature 40 and the pulley 30 by the attractive magnetic force generated by energization of the electromagnetic coil 51 has been described, but instead of this, Japanese Patent Laying-Open No. 2011-80579. The principle of the present disclosure may be applied to a self-holding electromagnetic clutch disclosed in a gazette (corresponding to US2011 / 083935A1).

Note that the present disclosure is not limited to the above-described embodiment, and can be appropriately changed within the scope of the present disclosure. 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, it is needless to say that elements constituting the embodiment are not necessarily indispensable except for the case where it is clearly indicated that the element is essential and the case where the element is clearly considered essential in principle. Yes. 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. 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.

Claims (6)

1. A drive-side rotator (30) that rotates about a rotation center line (O) by a rotational drive force from a drive source;
   When connected to the drive-side rotator (30), the driven-side rotator (40) rotates about the rotation center line (O) by the rotational driving force transmitted from the drive-side rotator (30). )When,
   An electromagnetic coil (51) comprising an aluminum material and having a wound wire (51a),
   The electromagnetic coil (51) causes the magnetic flux to pass through the boundary between the drive-side rotator (30) and the driven-side rotator (40) a plurality of times, so that the drive-side rotator (30) and the follower are driven. Forming a magnetic circuit (M) for generating an attractive magnetic force to connect the side rotating body (40);
   A predetermined number of magnetic poles are formed between the driving side rotating body (30) and the driven side rotating body (40),
   The said predetermined number is 6 or more, Comprising: The electromagnetic clutch which shows the frequency | count that the said magnetic flux passes the said boundary within the said magnetic circuit (M).
2. The drive-side rotator (30) is formed of a magnetic material into a ring shape concentric with the rotation center line (O), and the drive-side rotators (60, 61, 62, 63, 64) and two corresponding ones of the plurality of drive side magnetic portions (60, 61, 62, 63, 64) that are adjacent to each other in the radial direction. A plurality of drive-side nonmagnetic parts (65, 66, 67, 69)
   The driven-side rotating body (40) is formed of a magnetic material into a ring shape concentric with the rotation center line (O), and a plurality of driven-side magnetic portions (80, 81, 82, 85) and a plurality of driven-side magnetic portions (80, 81, 82, 85) formed between non-magnetic materials and respectively disposed between two corresponding ones that are adjacent to each other in the radial direction. A driven-side nonmagnetic part (83, 84, 86),
   The drive-side rotator (30) and the driven-side rotator (40) include the plurality of drive-side nonmagnetic portions (65, 66, 67, 69) of the drive-side rotator (30) other than the plurality of drive-side nonmagnetic portions (65, 66, 67, 69). The plurality of driven-side magnetic portions other than the drive-side magnetic portions (60, 61, 62, 63, 64) and the plurality of driven-side nonmagnetic portions (83, 84, 86) in the driven-side rotating body (40) The electromagnetic clutch according to claim 1, wherein the magnetic flux passes through (80, 81, 82, 85) to form the predetermined number of magnetic poles.
3. The electromagnetic clutch according to claim 2, wherein the plurality of drive-side nonmagnetic portions (65, 66, 67, 69) are each formed in a ring shape from the nonmagnetic material.
4. Each of the driving side nonmagnetic portions (65, 66, 67, 69) is formed of the nonmagnetic material, and is radial to each other among the plurality of driving side magnetic portions (60, 61, 62, 63, 64). Of the plurality of bridge portions (110) respectively connecting the corresponding two adjacent to each other and the plurality of driving side magnetic portions (60, 61, 62, 63, 64) adjacent to each other in the radial direction A plurality of gaps (111) disposed between two corresponding ones and disposed between two corresponding ones of the plurality of bridge portions (110) adjacent to each other in the circumferential direction. The electromagnetic clutch as described in.
5. The electromagnetic clutch according to any one of claims 2 to 4, wherein the plurality of driven-side nonmagnetic portions (83, 84, 86) are each formed in a ring shape by the nonmagnetic material.
6. Each of the driven side nonmagnetic portions (83, 84, 86) is formed of the nonmagnetic material and is adjacent to each other in the radial direction among the plurality of driven side magnetic portions (80, 81, 82, 85). Between a plurality of bridge portions (210) respectively connecting two corresponding portions, and the corresponding two of the plurality of driven side magnetic portions (80, 81, 82, 85) adjacent to each other in the radial direction. 5. The device according to claim 2, further comprising a plurality of gaps (211) disposed between two corresponding ones of the plurality of bridge portions (210) adjacent to each other in the circumferential direction. The electromagnetic clutch according to one item.

Images