JPH0238105Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to an electromagnetic clutch equipped with a surge absorbing device that absorbs surge voltage generated when power is cut off.

[Conventional technology]

Here, a conventional electromagnetic clutch will be explained with reference to FIG. The electromagnetic clutch includes an iron ring-shaped rotor 3 rotatably supported on the outer periphery of a cylindrical protrusion 1a of a fixed part 1 via a radial bearing 2, and a coil 10 and a diode 11 fixedly held on the fixed part 1. A plurality of hubs 6 include a ring-shaped core portion 4 arranged therein, a hub 6 which is attached to the tip of a main shaft 5 which passes through the cylindrical protrusion 1a and is rotatably supported by the fixing portion 1 while being prevented from rotating by a key 7. The armature 9 is connected to the hub 6 via a leaf spring 8, is opposed to the axial end surface 3a of the rotor 3, and is mounted so as to be movable in a direction parallel to the main shaft 5. In the electromagnetic clutch constructed as described above, the rotor 3 is rotated via a V-belt (not shown) stretched across the V-groove pulley 3b of the rotor 3, and at this time, the coil 10 is energized to rotate the rotor 3. Magnetic flux is generated and the armature 9 is attracted to the end surface 3a of the rotor 3, thereby transmitting rotational force to the main shaft 5. Further, when the current to the coil 10 is cut off, the magnetic flux disappears, and the armature 9 is separated from the end surface 3a of the rotor 3 by the restoring force of the leaf spring 8.

The drive of the compressor is controlled by repeating such operations, but when the power to the coil 10 is cut off,
A surge voltage is induced across the coil 10. This surge voltage increases in proportion to the current value or inductance at the time of interruption,
It can reach over 1000 volts. Such high voltages have adverse effects such as shortening the life of the switch contacts of the control device connected to the coil 10, causing voltage breakdown in semiconductors, and even causing malfunctions in semiconductor circuits. Ta. For this reason, in the conventional electromagnetic clutch, the core portion 4
A diode 11 was provided inside the coil for absorbing surge voltage, but since it is housed together with the coil 10, the temperature of the diode 11 also rises as the temperature of the coil 10 rises when energized, which often leads to destruction. Ta.

Furthermore, if a destructive failure occurs in the diode 11, it is difficult to replace only the diode 11, so the entire compressor must be replaced, resulting in high repair costs.

Therefore, taking these things into consideration, we have developed
In Publication No. 51026, various terminals of a lead wire and a ground wire of an electromagnetic clutch attached to a compressor of a vehicle air conditioner, and a surge absorbing diode bridging between the two external terminals are integrally formed with a resin mold, A surge absorbing device for an electromagnetic clutch is disclosed, characterized in that a ground terminal portion of the integrated body is locked to a predetermined portion of a compressor and its support including a fixed portion of the electromagnetic clutch.

[The problem that the idea aims to solve]

However, in this case, in order to prevent the diode from being destroyed due to high heat, the earth terminal part of the integrated body is locked to a predetermined part of the compressor and its support body, including the fixed part of the electromagnetic clutch. The effects of heat and vibration from high-temperature parts such as the high-pressure parts of compressors could not be avoided. Furthermore, even if high-temperature parts were avoided, it was inevitable that the diode would be exposed to heat exceeding the temperature inside the engine room.

Therefore, the purpose of the present invention is to eliminate the above drawbacks and
The objective is to provide an inexpensive and highly reliable electromagnetic clutch.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a clutch rotor rotationally driven by an external drive source and an armature disposed opposite to the clutch rotor, which are arranged so as to be stationary and fixed with a gap in the rotor. included in the magnetic circuit of the excitation coil device,
In an electromagnetic clutch that attracts and connects an armature to a clutch rotor by energizing an excitation coil and transmits rotational motion to a main shaft of a driven device, the excitation coil is connected to a lead wire led out to the outside of the excitation coil device, and A surge voltage absorbing device placed apart from the coil device is housed in a sleeve.

[Effect]

In the present invention, the surge voltage absorber connected to the lead wire led to the excitation coil device is placed apart from the excitation coil device, so that the heat of the excitation coil device is not conducted to the surge voltage absorber.

Further, by housing the surge voltage absorber in the sleeve, it is possible to protect the surge voltage absorber, increase its strength, insulate it, and simplify the installation work.

That is, since a heat shrinkable tube is generally used as the sleeve, the diode 341, the ground lead wire 35, and the terminal lead wire 343 are firmly fixed to each other by heat shrinkage. Therefore, during actual installation work, when connecting the external connection terminal 37 to the vehicle side connection terminal (not shown), there is no risk of damaging the diode because it is fixed inside the sleeve. Moreover, since it has a certain strength, the installation work is easy. Further, by housing the diode in the sleeve, it can be locked at a location such as the vehicle side where it is relatively less affected by heat and vibration. In addition, when connecting the external connection terminal to the mating connection terminal, the area around the diode must be insulated because the installation work involves touching the diode, but by storing it in a sleeve, an insulation effect can be obtained. be able to.

Furthermore, by housing the diode in a sleeve, it is possible to improve weather resistance such as salt spray resistance, water resistance, and moisture resistance of the diode, which not only protects the diode but also extends its life.

〔Example〕

Hereinafter, the present invention will be explained with reference to drawings showing embodiments.

FIG. 2 is a sectional view showing an embodiment of the present invention.
The excitation coil device of the electromagnetic clutch includes an iron ring-shaped rotor 23 rotatably supported on the outer periphery of the cylindrical protrusion 21a of the fixed part 21 via a radial bearing 22.
and a coil 3 inside which is fixedly held by the fixed part 21.
A ring-shaped core part 24 with a number 0 arranged thereon, and a cylindrical protrusion 2
A hub 26 is attached to the tip of a main shaft 25 rotatably supported by a fixed part 21 through the inside of the main shaft 25 while being prevented from rotating by a key 27. direction end face 2
3a and an armature 29 which is opposed to each other with a gap and is movably attached in a direction parallel to the main shaft 25. As shown in FIG. 3, one end 301 of the coil 30 disposed within the core section 24 passes through the insulating resin 241, connects to the round terminal 242, and is fixed to the core section 24 by the driving force of the rivet 243. ing. In addition, the other end 302 of the coil 30
is connected to a lead wire 31, and the lead wire 31 is led out to the outside of the core portion 24, and a female terminal 32 is attached to the tip. Inside the sleeve 34, as shown in FIG. 4, there is a male terminal 33 at one end for connecting to a female terminal 32 provided at the end of the lead wire 31 drawn out from the coil 30, and at the other end a male terminal 33 for connecting to an external terminal. A connecting terminal 37 is disposed via a terminal lead wire 343, and a diode 241 as a surge voltage absorber is integrally provided with one end connected to the male terminal 33 and the other end connected to the ground lead wire 35 via a connector 342. ing. A stop terminal 36 is attached to the tip of the ground lead wire 35, and the stop terminal 36 is fixed to the fixing portion 21 with a screw 361. Note that the connection portion between the male terminal 33 and the female terminal 32 is covered with a female sleeve 321.

The operation and effect of the electromagnetic clutch having such a structure will be explained with reference to FIG. 5 as well.

When the control switch 40 is closed and an excitation current is applied to the coil 30, a magnetic flux is generated that passes through the core section 24, clutch rotor 23, and armature 29, and the armature 29, which is in communication with the main shaft 25, is generated.
is attracted to the clutch rotor 23. Here, since the clutch rotor 23 is connected to the operation source via the V-belt stretched to the V-groove pulley 23b,
Since it is constantly rotating, armature 2
9 is attracted to the clutch rotor 23 and at the same time performs a rotational movement and transmits this rotational movement to the main shaft 25.

On the other hand, when the control switch 40 is opened, the coil 3
Since the excitation current to 0 is cut off, the magnetic flux passing through the core, rotor, and armature disappears, and the armature 29 is separated from the clutch rotor by the repulsive force of the leaf spring.

As a result, the transmission of driving force from the pulley 23 to the main shaft 25 is also eliminated.

Note that when the power is cut off, a back electromotive current, that is, a surge voltage is induced at both ends of the coil 30 compared to the current value at the time of cutoff and the inductance of the coil 30, but this surge voltage is quickly absorbed by the diode 341. and disappear.

According to the embodiment, by connecting a diode with a ground lead wire to the lead wire, it is possible to prevent shortening of the contact life of the control switch, damage to the semiconductor, or malfunction caused by surge voltage, and also to prevent the diode from being damaged or malfunctioning. Since the excitation coil device including the coil is arranged separately and housed in the sleeve, the diode is not directly exposed to the heat of the coil generated when energized, and the life of the diode can be significantly extended.

[Effect of idea]

As described above, according to the present invention, the surge voltage absorber connected to the lead wire led out to the excitation coil device is placed apart from the excitation coil device and housed in the sleeve. Although the heat of the room is conducted, the heat of the excitation coil device is not conducted, and significant effects such as protection of the surge voltage absorbing device, reinforcement of strength, insulation, and simplification and cost of transaction work can be obtained.

Although a diode is used as the surge absorbing device in this embodiment, a surge absorbing device having a characteristic of absorbing surge voltage such as a series connection of a capacitor and a resistor, a varistor, a surge absorbing tube, etc. may also be used.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing a conventional example, Fig. 2 is a cross-sectional view showing an embodiment of the present invention, Fig. 3 is an explanatory diagram showing an embodiment of the present invention, and Fig. 4 shows main parts of the present invention. The explanatory diagram, FIG. 5, is an electrical connection diagram in an embodiment of the present invention. 21... Fixed part, 21a... Cylindrical protrusion, 22...
... Bearing, 23 ... Rotor, 23a ... End surface, 23
b...Pulley, 24...Core part, 25...Main shaft,
26...hub, 27...key, 28...plate spring,
29... Armature, 30... Coil, 31...
... Lead wire, 32 ... Female terminal, 33 ... Male terminal, 34 ... Sleeve, 35 ... Earth lead wire, 36 ... Stop terminal, 37 ... External connection terminal,
341...Diode, 40...Control switch.

Claims (1)

[Scope of utility model registration request] A clutch rotor rotationally driven by an external drive source and an armature disposed opposite to the clutch rotor are included in a magnetic circuit of an excitation coil device disposed so as to be stationary and fixed with a gap within the rotor. In an electromagnetic clutch that attracts and connects an armature to a clutch rotor by energizing an excitation coil and transmits rotational motion to a main shaft of a driven device, the electromagnetic clutch is connected to a lead wire led out to the outside of the excitation coil device, and An electromagnetic clutch characterized in that a surge voltage absorber disposed apart from the excitation coil device is housed in a sleeve.