JP2990959B2 - Electromagnetic clutch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic clutch for interrupting transmission of rotational power.

[0002]

2. Description of the Related Art Conventionally, in an electromagnetic clutch mounted on a refrigerant compressor of a vehicle refrigeration cycle, a rubber hub is interposed between an inner hub and an outer hub so that the rubber hub can be displaced in a torque transmitting direction. This has the effect of reducing torque fluctuations on the refrigerant compressor side.

[0003]

However, it is difficult to properly optimize the spring constant (torsional spring constant) in the torque transmitting direction in order to restrict the physique and optimize the spring constant in the axial direction. However, the effect of reducing the torque fluctuation by the rubber hub is not sufficient. Therefore, torque fluctuation increases in the frequency range near the torsional resonance point of the vibration system of the electromagnetic clutch and the refrigerant compressor, and when the resonance range is close to the resonance point of the vehicle, noise increases due to the synergistic effect.
There was a problem that noise was transmitted to the vehicle interior. The present invention has been made based on the above circumstances, and an object of the present invention is to reduce noise fluctuation by reducing torque fluctuation transmitted to an electromagnetic clutch.

[0004]

In order to achieve the above object, the present invention provides an exciting coil which generates a magnetic force when energized, a driving member which is driven to rotate by a power source, and A rotating member that is attracted to the driving member when energized and rotates integrally with the driving member, a driven member that rotates integrally with a drive shaft of an auxiliary machine, and the rotating member and the driven member that are connected to each other, An elastic member that is provided so as to be capable of being elastically deformed and transmits the rotational power of the driving member to the driven member; and a friction member that engages with the rotating member and the driven member in a parallel relationship with the elastic member. The friction member has one end connected to one of the rotating member and the driven member, and the other end pressed by a predetermined force to the other of the rotating member and the driven member. Provided in contact with pressure Together, the technical means that it has elasticity in the circumferential direction.

[0005]

According to the electromagnetic clutch of the present invention having the above-described structure, when the rotational power is transmitted from the rotating member to the driven member via the elastic member, the load torque of the driven member fluctuates and the elastic member rotates in the rotational direction. When the relative rotational displacement (relative angular displacement) occurs between the rotating member and the driven member due to elastic deformation in the torsion direction), the repulsive force (torque) generated in the friction member is small in a range where the relative angular displacement is small. Therefore, no sliding occurs at the other end of the friction member that comes into contact with the rotating member or the driven member with a predetermined pressing force. Therefore, in this case, the spring constant in the torsional direction (rotation direction) is the sum of the torsional spring constant of the elastic member and the torsional spring constant of the friction member having elasticity in the circumferential direction. Move to a higher frequency range. Thereafter, the relative angular displacement between the rotating member and the driven member increases with an increase in torque fluctuation, and when sliding occurs at the other end of the friction member, the vibration energy due to the torque fluctuation generates heat due to the sliding of the friction member. By being converted into energy, torque fluctuation is reduced. In this case, since the other end of the friction member slides, the elastic action (spring action) of the friction member does not work between the rotating member and the driven member, and therefore, the spring constant in the torsion direction is reduced by the elastic member. And the resonance point of the torque fluctuation moves to a lower frequency range.

[0006]

Next, an embodiment of the electromagnetic clutch of the present invention will be described with reference to FIGS. FIG. 1 is a sectional view of the electromagnetic clutch. The electromagnetic clutch 1 of this embodiment is mounted on a refrigerant compressor (an auxiliary device of the present invention) of a vehicle refrigeration cycle,
The rotational power of the engine (the power source of the present invention) is transmitted to the drive shaft 2 of the refrigerant compressor as necessary. The electromagnetic clutch 1 is roughly divided into an exciting coil 3, a stator housing 4 supporting the exciting coil 3, a clutch rotor 5 (a driving member of the present invention) which rotates by transmitting the rotational power of the engine, and an exciting coil. 3 is energized, the armature 6 is attracted to one end surface (left side in FIG. 1) of the clutch rotor 5, a hub assembly (described later) supporting the armature 6, and a friction plate 7 mounted on the hub assembly. (Friction member of the present invention).

The exciting coil 3 is a known coil in which a conductive wire coated with an insulating film is wound around a resin bobbin 8, and generates a magnetic force when energized. The stator housing 4 is made of a magnetic material such as iron, and forms a magnetic path of the exciting coil 3 together with the clutch rotor 5. The clutch rotor 5 includes an exciting coil 3 supported by a stator housing 4.
U-shaped cross section that covers from one end side (inverted U-shaped in FIG. 1)
And is rotatably supported by a housing 10 of the refrigerant compressor via a ball bearing 9 arranged on the inner periphery thereof. A pulley 1 is provided on the outer periphery of the clutch rotor 5.
1 is fixed, and the multi-stage V
It rotates by the rotational power of the engine transmitted via a belt (not shown). The clutch rotor 5 is provided with a smooth friction surface at one end surface in the axial direction, and closes the inner circumference and the outer circumference of the friction surface to shut off magnetism acting on the clutch rotor 5 when the excitation coil 3 is energized. hand,
A long hole 5a for bypassing the magnetic flux flowing in the radial direction is formed over substantially the entire circumference.

The armature 6 has a hollow disk shape and has a predetermined gap in the axial direction, and is arranged to face the friction surface of the clutch rotor 5. This armature 6
The other end surface facing the friction surface of the clutch rotor 5 is a smooth friction surface. When the exciting coil 3 is energized, it is attracted to the clutch rotor 5 side and engages with the clutch rotor 5 by engagement of both friction surfaces. They rotate together. The armature 6 has an armature 6 like the clutch rotor 5.
A long hole 6a is formed over substantially the entire circumference to cut off the magnetic force acting on the magnet and to bypass the magnetic flux. A ring shield 12 sandwiched between the clutch rotor 5 and the ball bearing 9 is provided on the inner peripheral side between the friction surface of the clutch rotor 5 and the friction surface of the armature 6. The ring shield 12 is provided so as to extend in the axial direction from the clutch rotor 5 side to the armature 6 side. When the clutch rotor 5 rotates, oil or lubricant or the like is scattered, and the friction surface of the clutch rotor 5 or the friction of the armature 6 is increased. This is to prevent adhesion to the surface.

The hub assembly includes an outer hub 13 fixed to one end of the armature 6, an inner hub 14 (a driven member of the present invention) coaxial with the outer hub 13 and arranged on the inner peripheral side of the outer hub 13. And a rubber hub 15 (elastic member of the present invention) connecting the inner hub 13 and the inner hub 14. The rotating member according to the present invention includes the armature 6 and the outer hub 13. The outer hub 13 has an annular shape having an L-shaped cross section (an inverted L-shape in FIG. 1), and is fixed to the outer peripheral portion of the armature 6 with three rivets 16. The inner hub 14 is provided in a stepped cylindrical shape, and is fixed to the drive shaft 2 of the refrigerant compressor. The rubber hub 15 is radially interposed between the inner peripheral surface of the outer hub 13 and the outer peripheral surface of the inner hub 14,
They are bonded and fixed to both, and are set so as to keep a gap of about 0.5 mm between the friction surface of the armature 6 and the friction surface of the clutch rotor 5 when the excitation coil 3 is not energized. The armature 6 is attracted to the clutch rotor 5 side when the exciting coil 3 is energized, so that the rubber hub 15 includes an outer hub 13 moving integrally with the armature 6 and an inner hub fixed to the drive shaft 2 of the refrigerant compressor. 14, an elastic deformation occurs in the axial direction, and the excitation coil 3
When the power supply to the armature is stopped, the armature 6 is returned to the initial position (the position shown in FIG. 1) by the elastic force.

The friction plate 7 is disposed at one end of the hub assembly, and is fixed to the wall surface of the inner hub 14 by three screws 17. The friction plate 7 is made of a steel plate or a stainless steel plate, and is formed into a stepped disk shape according to the outer shape of the hub assembly as shown in FIG. 2 (a perspective view of the friction plate 7) by means such as press working. A plurality (three in this embodiment) of projecting portions 7a are provided at equal intervals in the circumferential direction of the friction plate 7 on the outer peripheral edge portion (see FIG. 3 and a view A in FIG. 1). Each protruding portion 7a is provided so as to be bent inward of the friction plate 7 so as to have elasticity in the radial direction, and the distal end portion of the outer hub 13 is provided with the friction plate 7 mounted on the hub assembly. A contact portion 7b that contacts the outer diameter wall surface with a predetermined pressing force is bent. For this reason, the diameter of the circle connecting the contact portions 7b is provided to be slightly smaller than the outer diameter of the outer hub 13, and the contact portion 7b is pressed against the contact portion 7b by the interference between the outer hub 13 and the contact portion 7b during assembly. Pressure develops. Therefore, by adjusting the interference, the friction torque between the outer hub 13 and the friction plate 7 (the contact portion 7b) can be adjusted. In addition, each protruding portion 7a
Is provided with a constant width h in the circumferential direction of the friction plate 7,
It has a spring action (elastic action) in the circumferential direction. Therefore, by changing the circumferential width h, the circumferential spring constant, that is, the torsional spring constant Ka can be adjusted. For example, by increasing the width h, the torsional spring constant Ka increases, By reducing h, the torsional spring constant Ka decreases.

Next, the operation of this embodiment will be described. The armature 6 is attracted to the clutch rotor 5 side against the elastic force of the rubber hub 15 by the magnetic force generated by energizing the excitation coil 3. As a result, the friction surface of the clutch rotor 5 and the friction surface of the armature 6 come into close contact and frictionally engage with each other. 2
Is transmitted to When the energization of the excitation coil 3 is stopped,
Since the magnetic force generated by the exciting coil 3 disappears, the armature 6 attracted to the clutch rotor 5 is separated from the clutch rotor 5 by the elastic force of the rubber hub 15 and returns to the initial position. As a result, the frictional engagement between the clutch rotor 5 and the armature 6 is released, and the rotational power of the engine transmitted to the clutch rotor 5 is not transmitted to the drive shaft 2 of the refrigerant compressor.

Here, when the load torque applied to the drive shaft 2 of the refrigerant compressor fluctuates due to the compression action of the refrigerant, the torque fluctuation is transmitted from the drive shaft 2 to the electromagnetic clutch 1 side. Due to this torque fluctuation, when relative rotation (relative angular displacement) occurs between the outer hub 13 and the inner hub 14 due to elastic deformation in the rotational direction of the rubber hub 15, when the relative angular displacement is small, the friction plate 7 Since the repulsive force (torque) generated at the contact portion 7b is small, the contact portion 7b does not slide with respect to the outer hub 13. Therefore, in this case, the overall spring constant in the torsional direction is the sum of the torsional spring constant Kd of the rubber hub 15 and the torsional spring constant Ka of the friction plate 7, and the resonance point of the torque fluctuation is as shown by the broken line b in FIG. Then, it moves to a higher frequency range f1 than when only the rubber hub 15 is used. FIG. 4 is a graph showing the relationship between the torque amplitude and the frequency of the torque fluctuation. The frequency of the torque fluctuation is 1: 1 with the rotation speed of the refrigerant compressor.
In a relationship. In the figure, the graph indicated by the broken line a shows the torque fluctuation when only the rubber hub 15 is used.
The graph shown by the broken line b shows the torque fluctuation when the rubber hub 15 and the torsion spring action of the friction plate 7 are used together, and the graph shown by the solid line c shows the torque fluctuation of the present embodiment.

When the frequency of the torque fluctuation increases, the torque amplitude increases, and the relative angular displacement between the outer hub 13 and the inner hub 14 increases, frictional sliding occurs between the contact portion 7b of the friction plate 7 and the outer hub 13. (Point d in FIG. 4). By this frictional sliding, vibration energy is absorbed and converted into heat generation energy, so that torque fluctuation is reduced.
In this case, the elastic force (spring force) of the friction plate 7 does not act between the outer hub 13 and the inner hub 14 due to the sliding of the contact portion 7b. With only the constant Kd, the resonance point of the torque fluctuation moves to the lower frequency range f2 as shown by the broken line a in FIG.

The relationship between the friction torque applied to the contact portion 7b of the friction plate 7 and the peak value of the torque amplitude is, for example, as shown in FIG. 5, there is an optimum value e of the friction torque for minimizing the torque amplitude. I do. The optimum value e of this friction torque is
As shown in the graph of FIG. 6, the value varies depending on the torsional spring constant Ka of the friction plate 7. In addition, the magnitude of the damping effect of the torque fluctuation due to the frictional sliding of the contact portion 7b is proportional to the friction torque. Therefore, when the friction torque is small, the damping effect is small.
On the other hand, if the friction torque is too large, the contact portion 7b is unlikely to slide, so that the damping effect is also small. As described above, in the present embodiment, the torque fluctuation can be reduced, and the resonance point of the torque fluctuation is shifted by switching the entire torsional spring constant when the amplitude of the vibration is large to move the resonance point. By moving away from the frequency,
Noise can be effectively reduced. In this embodiment, the pressing force of the contact portion 7b may be adjusted by adjusting means such as a screw.

FIG. 7 shows a second embodiment of the present invention. In the present embodiment, the friction plate 7 is fixed to the outer hub 1 by the rivets 16.
3, the contact portion 7 b of the friction plate 7 is pressed against the inner diameter of the inner hub 14. FIG. 8 shows a third embodiment of the present invention.
An example will be described. In the present embodiment, the friction plate 7 is
The contact portion 7 b is fixed to the other end surface of the arm 4 by a screw 17, and is pressed against the inner diameter of the armature 6.

[0016]

According to the electromagnetic clutch of the present invention, the torque fluctuation can be reduced and the resonance frequency can be shifted according to the amplitude of the vibration accompanying the torque fluctuation, thereby effectively reducing the noise. Can be.

[Brief description of the drawings]

FIG. 1 is a sectional view of an electromagnetic clutch according to a first embodiment.

FIG. 2 is a perspective view of a friction plate according to the first embodiment.

FIG. 3 is a view as viewed from A in FIG. 1;

FIG. 4 is a graph showing the relationship between torque amplitude and torque fluctuation frequency.

FIG. 5 is a graph showing a relationship between a friction torque and a peak value of a torque amplitude.

FIG. 6 is a graph showing a relationship between an optimum value of friction torque and a torsion spring constant of a friction plate.

FIG. 7 is a sectional view of a main part of an electromagnetic clutch showing a second embodiment of the present invention.

FIG. 8 is a sectional view of a main part of an electromagnetic clutch showing a third embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 electromagnetic clutch 2 drive shaft 3 excitation coil 5 clutch rotor (drive member) 6 armature (rotation member) 7 friction plate (friction member) 13 outer hub (rotation member) 14 inner hub (following member) 15 rubber hub (elastic member)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-20540 (JP, U) JP-A 62-16837 (JP, U) JP-A 4-132229 (JP, U) JP-A 4- 3145 (JP, U) JP-A 3-86230 (JP, U) JP-A 62-155249 (JP, U) JP-A 63-86431 (JP, U) (58) Fields surveyed (Int. Cl. ⁶ , DB name) F16D 27/10

Claims (1)

(57) [Claims] A) an exciting coil which generates a magnetic force when energized; b) a driving member which is driven to rotate by a power source; c) said driving member is attracted to said driving member when energizing said exciting coil. A rotating member that rotates integrally with the driving member; d) a driven member that rotates integrally with the driving shaft of the auxiliary machine; e) the rotating member and the driven member are connected and elastically deformable therebetween. An elastic member for transmitting the rotational power of the driving member to the driven member; and f) a friction member engaged with the rotating member and the driven member in a parallel relationship with the elastic member. One end of the friction member is connected to one of the rotating member and the driven member, and the other end contacts the other of the rotating member and the driven member with a predetermined pressing force. And elastic in the circumferential direction Electromagnetic clutch, characterized in that it comprises.