JPH032010Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electromagnetic clutch suitable for output switching in micro printers and the like.

[Prior Art] An electromagnetic clutch is used as a mechanism for controlling the output of power input to a clutch gear to an electromagnetic plate. The configuration of the electromagnetic clutch will be explained below based on the drawings. FIG. 3 is an exploded perspective view showing the structure of a general electromagnetic clutch. As shown, a rotating shaft 1 connected to a clutch gear 1
A plate spring 2 and an electromagnetic plate 3 are loosely fitted into the part a, and an electromagnetic yoke 5 is also press-fitted therein. The electromagnetic yoke 5 is open downward and has a substantially cup-shaped shape with a protrusion 5b formed in the center thereof, and the rotation shaft 1 is inserted into the through hole formed in the center protrusion 5b.
A is press-fitted. The electromagnetic coil 4 is inserted into the hollow part of the electromagnetic yoke 5, and the lower end surface 5
a and 5b face the upper surface of the electromagnetic plate 3. Further, the plate spring 2 is an electromagnetic plate 3.
Its role is to press the electromagnetic yoke 5 side.
Therefore, when a motor (not shown) rotates, the rotational force of the motor is input to the clutch gear 1 through a transmission mechanism consisting of gears, etc., and the electromagnetic yoke 5 rotates together with the clutch gear 1, but the electromagnetic plate 3 only receives frictional force. Does not have large rotational force. However, when the electromagnetic coil 4 is energized, the electromagnetic yoke 5
is magnetized and attracts the electromagnetic plate 3. Therefore, the rotational force of the electromagnetic yoke 5 is transmitted to the electromagnetic plate 3, and the electromagnetic plate 3 rotates.

As described above, in the electromagnetic clutch, the output of the power input to the clutch gear 1 to the electromagnetic plate 3 is controlled by controlling the energization to the electromagnetic coil 4.

FIG. 4 is a sectional view of a conventional electromagnetic yoke 5. As shown in the figure, the protrusion 5b at the substantially central portion and the outer peripheral wall 5a are formed at substantially the same height.

[Problems to be solved by the invention] However, in the above conventional example, the electromagnetic coil 4
When the electromagnetic yoke 5 is magnetized, the fifth
If the electromagnetic plate 3 is warped as shown in the figure, the area of close contact between the electromagnetic yoke 5 and the lower surface of the outer peripheral wall 5a becomes smaller, and the absorption force of the electromagnetic yoke 5 becomes weaker.
There was a problem that the rotational force of the electromagnetic yoke 5 was not transmitted to the electromagnetic plate 3.

An object of the present invention is to provide an electromagnetic clutch in which the electromagnetic plate 3 is always absorbed by the electromagnetic yoke 5 with a strong force when the electromagnetic coil 4 is energized, regardless of the warpage of the electromagnetic plate 3.

[Means for Solving the Problems] In order to achieve the above object, the present invention forms a convex portion 5c at a substantially central portion of the electromagnetic yoke 5 higher than the outer peripheral wall 5a, and attaches an electromagnetic plate 3 to the convex portion 5c. It is characterized by being loosely fitted.

[Function] By loosely fitting the hole of the electromagnetic plate 3 into the convex portion 5c at the substantially central portion which is higher than the outer circumferential wall 5a, even if the electromagnetic plate 3 is warped, it will be in close contact evenly with the lower surface of the outer circumferential wall 5a, so that it will always remain in close contact with the lower surface of the outer circumferential wall 5a. The electromagnetic plate 3 is absorbed by the electromagnetic yoke 5 with a strong force.

[Example] An example of the present invention will be described below with reference to FIGS. 1 and 2. Note that the same parts as in the conventional example are given the same numbers, and detailed explanations are omitted. Further, since the mechanism of the present invention is the same as a general electromagnetic clutch, only the points different from the conventional example will be explained.

FIG. 1 is a cross-sectional view of an electromagnetic yoke 5 according to the present invention, in which a convex portion 5c approximately at the center is formed higher than the outer circumferential wall 5a, and the electromagnetic plate 3 is loosely fitted into the convex portion 5c. Therefore, when the electromagnetic coil 4 is energized and the electromagnetic yoke 5 is magnetized, even if the electromagnetic plate 3 is warped, the electromagnetic plate 3 is moved to the protrusion at the approximate center of the electromagnetic yoke 5 as shown in FIG. 5c
Since it is loosely fitted into the outer peripheral wall 5a of the electromagnetic yoke 5,
The electromagnetic plate 3 can be evenly adhered to the lower surface, the area of close contact is large, the electromagnetic plate 3 is absorbed by the electromagnetic yoke 5 with a strong force, and the rotational force of the electromagnetic yoke 5 is transmitted to the electromagnetic plate 3.

[Effects of the Invention] As explained above, according to the present invention, the convex portion at the approximate center of the electromagnetic yoke is formed higher than the outer peripheral wall,
Because the electromagnetic plate is loosely fitted into the convex part, regardless of the warpage of the electromagnetic plate, when the electromagnetic coil is energized, the electromagnetic plate is always absorbed by the electromagnetic yoke with a strong force, and the rotational force of the electromagnetic yoke is ensured. It has the remarkable effect of being transmitted to the electromagnetic plate.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the electromagnetic yoke of the present invention, Figure 2 is an explanatory diagram of the contact state between the electromagnetic yoke and the electromagnetic plate of the present invention, Figure 3 is an exploded perspective view of a general electromagnetic clutch, and Figure 4 is an exploded perspective view of a general electromagnetic clutch. FIG. 5, which is a sectional view of a conventional electromagnetic yoke, is an explanatory diagram of a state of contact between a conventional electromagnetic yoke and an electromagnetic plate. 1...Clutch gear, 1a...Rotating shaft, 2...
Plate spring, 3...electromagnetic plate, 4...electromagnetic coil, 5...electromagnetic yoke.

Claims (1)

[Scope of utility model registration request] In an electromagnetic clutch consisting of an electromagnetic plate, an electromagnetic yoke, a plate spring that presses the electromagnetic plate against the electromagnetic yoke, and a clutch gear that rotates integrally with the yoke, a convex portion at approximately the center of the yoke is formed higher than an outer peripheral wall. An electromagnetic clutch characterized in that the electromagnetic plate is loosely fitted into the convex portion.