JPH04236825A - Electromagnetic clutch - Google Patents

Abstract

PURPOSE:To prevent any increase in adsorption sound caused by joint of mutually mating metallic surfaces due to repeat of engagement and disengagement at the most outer periphery of a friction surface. CONSTITUTION:In a rotor side friction surface 3a, a step is provided on the outside friction surface 3b of a friction material 10 in the slightly recessed direction from the inside friction surface 3c so that even when the friction material 10 wears, the inside friction surface 3c may start join with an armature plate 6.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to the reduction of adsorption noise generated when an electromagnetic clutch is operated, and is suitable for, for example, an electromagnetic clutch that interrupts the transmission of driving force to a compressor attached to an automobile air conditioner. It is something.

0002

2. Description of the Related Art Conventionally, in an electromagnetic clutch, a friction material is fixed to the friction surface of a rotor to improve friction torque and reduce adhesion noise by joining with an armature.

The general structure of this type of electromagnetic clutch is as follows:
It is configured as shown in FIG. That is, as shown in the figure, a small magnetic space 4 is placed between the hub 2 connected to the main shaft 1, the rotor 3 connected to the engine by a V-belt, and the rotor 3 is coaxially connected to the rotor 3. An armature plate 6, which is a movable plate, is attached to the hub 2 via a leaf spring 5, and an excitation coil 9 that generates an electromagnetic force for frictionally coupling the rotor 3 and the armature plate 6 is disposed in the hub 2. A field core 7 of an excitation device consisting of an annular, U-shaped cross-section yoke member 8 that is housed and forms part of a magnetic circuit.
It is made up of.

Reference numeral 10 denotes an annular friction material, which is fixed to an annular groove 3d formed in the friction surface 3a of the rotor 3 by adhesive or the like. In addition, as shown in the longitudinal cross-sectional view of the rotor in FIG.
The surface 10a of the friction material 10 protrudes from the rotor friction surface 3a by a very small amount x dimension, and at the time of suction, the friction surface 6a of the armature plate 6 and the rotor friction surface 3a are brought into contact with each other.
By joining with the surface 10a of the friction material 10, friction torque is improved and adsorption noise is reduced. This protrusion amount x dimension is usually 0.05 to 0.05 to the extent that the friction material 10 is compressed and deformed by the suction force of the armature and becomes zero.
It is about 0.10.

[0005] The friction material 10 is made of organic fiber or inorganic fiber as a base material, and contains fillers for improving friction characteristics and wear resistance.
It is made by mixing metal powder, graphite, etc. and heat-molding it with a resin binder, and is used to have a large surface friction coefficient and excellent wear resistance.

[0006]

[Problems to be Solved by the Invention] However, the electromagnetic clutch having the above structure has a problem in that the suction noise during operation increases rapidly due to repeated attachment and detachment.

[0007] That is, by repeatedly attaching and detaching the
The friction material 10 is worn out, and the rotor friction surface 3a and the friction material surface 1
0a become almost the same surface, the outermost peripheral surface 6b of the armature plate friction surface 6a and the outermost peripheral surface 3b of the rotor friction surface
The parts begin to join together, and the adsorption noise increases as the metal surfaces join together at the outermost periphery.

Normally, it is preferable for the friction surfaces of an electromagnetic clutch to be joined on the outer periphery side rather than on the inner periphery side in order to secure friction torque, so the armature plate friction surface 6
Both the rotor friction surface 3a and the rotor friction surface 3a are set to have a concave shape. Therefore, as described above, when the friction material is worn out due to attachment and detachment, the friction surfaces are joined at the outermost periphery.

[0009]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a step on the rotor-side friction surface of the outer friction surface of the friction material in a concave direction by a slightly smaller amount than the inner friction surface of the friction material. The point is that even when the friction material wears out, the inner friction surface of the friction material begins to join with the armature plate.

0010

[Operation] As mentioned above, by providing a step in the rotor friction surface on the outside of the friction material in a concave direction from the inside, the friction material is worn out due to repeated attachment and detachment, and the armature plate friction surface and rotor friction surface Even when the friction material begins to bond, the metal surfaces begin to bond to each other from the inside of the friction material, relaxing the bond only at the outer periphery of the friction surface, and suppressing the increase in adhesion noise caused by repeated attachment and detachment.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the accompanying drawings. Here, parts that are the same as those of the conventional electromagnetic clutch are designated by the same reference numerals and explanations thereof will be omitted.

FIG. 1 is an enlarged vertical cross-sectional view of the rotor friction surface in the electromagnetic clutch of the present invention. The difference from the conventional electromagnetic clutch is that the friction material 10 is used on the rotor side friction surface 3a.
The outer friction surface 3b of the friction material 10 is stepped in the concave direction by a slight amount y dimension from the inner friction surface 3c of the friction material 10.

With the above structure, at the initial stage of attachment and detachment, the joint surface between the armature plate 6 and the rotor 3 is the joint between the rotor-side friction material surface 10a and the opposing armature plate friction surface 6a, as shown in FIG. 2, as in the conventional case. is the same as However, after repeated attachment and detachment, when the friction material 10 wears out, as shown in FIG.
As shown in FIG. 2, the rotor-side friction surface 3a begins to join the inner friction surface 3c of the friction material and the armature plate friction surface 6c facing thereto. At this point, the joining of metal surfaces begins, but unlike conventional joining from the outermost periphery, the joining is mainly between metal surfaces, whereas joining from the inside of the friction material, and moreover, the joining from the outermost periphery Since the parts are still joined,
The joining of the metal surfaces 3c and 6c and the joining of the friction material 10a and the metal surface 6a are performed simultaneously, and there is almost no increase in adsorption noise.

If the attachment and detachment are repeated again, as shown in FIG. 4, the wear on the friction surfaces will increase and the rotor outermost circumference 3b and the armature outermost circumference 6b will begin to be joined, but at this point , the amateur side friction surface 6a is made of the friction material 1
0, the amount of wear is less than that of the friction surfaces 6b and 6c that connect with other rotor-side metal surfaces 3b and 3c.
It has a more convex shape than c, and is always in contact with the friction material 10. Further, since the friction surfaces 3c and 6c are also joined, and the friction surfaces are joined over the entire surface and also joined using a friction material, there is almost no increase in adsorption noise.

Note that the step y dimension between the rotor outer friction surface 3b and the rotor inner friction surface 3c is such that when the friction material 10 wears out, the rotor inner friction surface 3c reaches the amateur side friction surface 6c slightly earlier than the rotor outer friction surface 3b. If the setting is made extremely large, the space between the rotor outer friction surface 3b and the armature side friction surface 6b will become larger and the suction force will decrease. There is a need to.

[0016]

Effects of the Invention As described above, the present invention provides a step on the rotor-side friction surface of the outer friction surface of the friction material that is slightly concave than the inner friction surface of the friction material, thereby making it possible to repeatedly attach and detach the friction surface. Even when the friction material wears out, bonding between metal surfaces starts from the inner friction surface of the friction material, and the friction material and armature plate are constantly bonded, making it possible to suppress an increase in adsorption noise.

[Brief explanation of the drawing]

[Fig. 1] Enlarged view of the rotor friction surface of an electromagnetic clutch in an embodiment of the present invention.

[Figure 2] Enlarged view of the friction surface of the rotor and armature

[Figure 3]
Enlarged view of the friction surface of the rotor and armature

[Figure 4] Enlarged view of the friction surface of the rotor and armature

[Figure 5] Longitudinal cross-sectional view of a conventional electromagnetic clutch

[Figure 6] Enlarged view of rotor friction surface of conventional electromagnetic clutch

[Explanation of symbols]

3 Rotor 9 Excitation coil 10 Friction material

Claims (1)

[Claims] 1. An electromagnetic clutch comprising a rotor driven by a V-belt from an engine, an excitation coil that generates electromagnetic force, and an armature that repeatedly attracts and detaches from the rotor by energizing the excitation coil, A friction material protruding from the friction surface by a minute amount is fixed to the friction surface of the rotor, and the outer friction surface of the friction material is stepped slightly in a concave direction from the inner friction surface of the friction material. Electromagnetic clutch.