JPH06193652A - Slip clutch - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to a slip clutch for transmitting a rotational force of a drive shaft to a driven shaft, and an object thereof is to provide a slip clutch in which slip torque can be easily adjusted and downsized. [Structure] A clutch plate 32 made of a ferromagnetic material fixed to a drive shaft 4, a slip plate 34 made of a ferromagnetic material fixed to a driven shaft 10 and closely sliding on the clutch plate 32, and a supplied exciting current. Accordingly, it comprises an exciting means for magnetizing the slip plate 34 and a means for varying the exciting current.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slip clutch for transmitting a rotational force of a drive shaft to a driven shaft. When transmitting the rotational force of the drive shaft connected to the power source such as a motor to the driven shaft on the power transmission side, if the power transmission side becomes faulty and the power transmission side becomes unrotatable, etc. An excessive load may occur and the power source may be damaged. In such a case, the slip clutch is used to transmit the rotational force of the drive shaft to the driven shaft.

The slip clutch transmits the kinetic energy of the power source to the driven shaft at a torque smaller than the slip torque (torque at which slip begins to occur), and a part of the kinetic energy of the drive source at a torque larger than the slip torque. Alternatively, by converting all of them into friction heat, it is possible to prevent an excessive load from being generated in the power source.

The field of application of such a slip clutch is wide, and there is a demand for a slip clutch having a simple structure.

[0004]

2. Description of the Related Art FIG. 3 is a side view of a power transmission device having a conventional slip clutch. Power source 2 consisting of a motor
When the drive shaft 4 connected to is rotated, its rotational force is transmitted to the driven shaft 10 via the gear 6 and the slip clutch 8. The slip clutch 8 is a gear 12 that meshes with the gear 6.
have.

For example, when a failure occurs on the power transmission side (driven portion) to which the driven shaft 10 is connected and the driven shaft 10 becomes unrotatable, a slip occurs in the slip clutch 8 and the gears 6 and 12 move. The power source 2 is prevented from idling and being overloaded.

FIG. 4 is a detailed sectional view of the slip clutch 8 of FIG. The driven shaft 10 rotatably supported by the bearings 14 and 16 is provided with a lock nut 18, a slip torque adjusting screw 20, a spring 22, a clutch plate 24, a gear 12, and a clutch plate 26 in this order.

The gear 12 can rotate independently of the driven shaft 10, and a slip piece 28 made of resin or the like seated in the depressions on the upper and lower surfaces of the gear 12 is in pressure contact with the clutch plates 24 and 26.

The amount of flexure of the spring 22 is changed by rotating the slip torque adjusting screw 20, whereby the slip torque corresponding to the torque used on the power transmission side is set. If there is no obstacle on the power transmission side and the torque received by this slip clutch is smaller than the slip torque,
The rotational force of the drive shaft is transmitted to the driven shaft without slipping between the slip piece 18 and the clutch plates 24 and 26.

When the driven shaft 10 becomes unrotatable due to a failure on the power transmission side, the slip piece 28 and the clutch plates 24 and 26 slip, and the gears 6 and 1
The idling of 2 prevents the power source from being overloaded.

[0010]

In the above-mentioned conventional slip clutch, since the rotational force of the drive shaft is transmitted to the driven shaft through the two gears, the device is large due to the space for disposing these gears. In addition, there is a problem in that the backlash of the gears is complicated to adjust and the assembly requires a large number of steps.

In addition, when adjusting the slip torque, it is necessary to loosen the lock nut once, rotate the slip torque adjusting screw, and then tighten the lock nut again, which makes it difficult to adjust the slip torque.

Therefore, an object of the present invention is to provide a slip clutch in which the slip torque can be easily adjusted and the size can be reduced.

[0013]

According to the present invention, there is provided a slip clutch for transmitting a rotational force of a drive shaft to a driven shaft, the ferromagnet being fixed to the drive shaft and having a sliding surface perpendicular to its rotation center. A clutch plate made of a body, a slip plate made of a ferromagnetic material having a sliding surface fixed to the driven shaft and in close contact with the sliding surface of the clutch plate, and the clutch plate and the clutch plate depending on the supplied exciting current. There is provided a slip clutch provided with an exciting means for magnetizing at least one of the slip plates and a means for varying the exciting current.

[0014]

According to the present invention, in the slip clutch for transmitting the rotational force of the drive shaft to the driven shaft, the clutch plate and the slip plate made of a ferromagnetic material are fixed to the drive shaft and the driven shaft, respectively. Since the exciting means for magnetizing at least one of them is provided and the exciting current is made variable, the slip torque can be changed by the exciting current, and the slip torque can be easily adjusted.

Further, since the drive shaft and the driven shaft can be arranged coaxially, the size can be greatly reduced as compared with the conventional structure using gears.

[0016]

EXAMPLES Examples of the present invention will be described below. FIG. 1 is a side view of a power transmission device to which a slip clutch of the present invention is applied, and FIG. 2 is an exploded perspective view of its main part. Throughout the drawings, substantially the same parts are designated by the same reference numerals.

The drive source 2 such as a motor is fixed to the upper surface of the device frame 30. Drive shaft 4 connected to power source 2
Penetrates through the opening of the device frame 30. A clutch plate 32 is fixed to the tip of the drive shaft 4. The clutch plate 32 is made of a ferromagnetic material such as iron, and the clutch plate 32 has a sliding surface 32A perpendicular to the center of rotation.

A driven shaft 10 provided coaxially with the drive shaft 4.
A slip plate 34 made of a ferromagnetic material such as iron is fixed to the tip of the slip plate 34. The slip plate 34 has a sliding surface 34A that is in close contact with the sliding surface 32A of the clutch plate 32. At least one of the drive shaft 4 and the driven shaft 10 is provided so as to be slightly movable in the axial direction.

In this embodiment, an electromagnetic coil 36 is provided to magnetize the slip plate 34. As shown in FIG. 2, the slip plate 34 includes a large-diameter flange portion 34B having a sliding surface 34A and a flange portion 34B.
B and a fixing portion 34C that is provided coaxially and has a smaller diameter than this. A hole is formed in the fixing portion 34C, and the slip plate 34 and the driven shaft 10 are mutually fixed by inserting and fixing the driven shaft 10 in this hole.

A screw is formed on the outer periphery of the fixing portion 34C of the slip plate 34, and the electromagnetic coil 36 is screwed into this screw and fixed to the slip plate 34. In the electromagnetic coil 36, reference numerals 36A and 36B are sliding electrodes connected to both ends of the coil, and an exciting current from a variable current source (not shown) is generated between these sliding electrodes 36A and 36B and a brush (not shown) sliding on them. Through the electromagnetic coil 3
6 is supplied.

Now, the strength H of the magnetic field formed by the electromagnetic coil 36 is given by the following equation, where I is the exciting current, N is the number of coil turns, and R is the coil radius. H = IN / 2R (A · turn / m) On the other hand, the attraction force of the clutch plate 32 and the slip plate 34 depends on the magnetization intensity of the slip plate 34, and the magnetization intensity of the slip plate 34 is as described above. Depends on the strength of the magnetic field given by Therefore, if the slip torque is set large in order to hold a large torque, the exciting current value should be increased, and if the slip torque is set small to hold a small torque, the exciting current value should be set small. It should be done.

Further, when it is difficult to use a larger electromagnetic coil due to size restrictions or the like, the required slip torque can be obtained by increasing the current value. In the present embodiment, when a torque smaller than the set slip torque is applied to the slip clutch, the rotational force of the drive shaft 4 is changed by the frictional force due to the suction force generated between the clutch plate 32 and the slip plate 34. 10 is transmitted.
When the torque acting on the slip clutch becomes larger than the set slip torque, the clutch plate 32 is prevented from slipping on the slip plate 34 and the power source 2 is not overloaded.

In this embodiment, since the exciting current supplied to the electromagnetic coil 36 is adjusted by the variable current source, the slip torque can be adjusted very easily and the variable width of the slip torque can be adjusted by the conventional technique. It can be greatly expanded compared to the case.

According to this embodiment, the clutch plate 32
Since the drive shaft 4 and the driven shaft 10 can be arranged coaxially with each other because the slip plate 34 and the slip plate 34 are abutted with each other, compared to the conventional case where a slip clutch is formed using two gears. Therefore, the size of the device can be greatly reduced.

Furthermore, since no gear is used as a component of the slip clutch, complicated work such as adjustment of backlash is not required, and the assembly of the device is facilitated. In the embodiment described above, the electromagnetic coil as the exciting means is provided on the side of the slip plate 34 to mainly magnetize the slip plate 34. However, the exciting means magnetizes the clutch plate 32 or the clutch plate 32 and the slip plate 34. The configuration may be changed as described above.

[0026]

As described above, according to the present invention,
The slip torque can be easily adjusted, and the slip clutch suitable for downsizing can be provided.

[Brief description of drawings]

FIG. 1 is a side view of a power transmission device to which a slip clutch of the present invention is applied.

FIG. 2 is an exploded perspective view of a main part of the apparatus shown in FIG.

FIG. 3 is a side view of a power transmission device to which a conventional slip clutch is applied.

4 is a detailed cross-sectional view of the device of FIG.

[Explanation of symbols]

 4 Drive shaft 10 Driven shaft 32 Clutch plate 34 Slip plate

Claims (2)

[Claims] 1. A slip clutch for transmitting the rotational force of a drive shaft (4) to a driven shaft (10), which is a ferromagnet fixed to the drive shaft (4) and having a sliding surface perpendicular to its rotation center. A slip plate made of a ferromagnetic body having a clutch plate (32) made of a body and a sliding surface fixed to the driven shaft (10) and in close contact with the sliding surface of the clutch plate (32).
(34), an exciting means for magnetizing at least one of the clutch plate (32) and the slip plate (34) according to the supplied exciting current, and a means for varying the exciting current. And slip clutch. 2. The slip plate (34) is fixed to the driven shaft (10) integrally provided with the flange portion (34B) having the sliding surface and the flange portion (34B). Department (34C)
The slip clutch according to claim 1, wherein the exciting means includes an electromagnetic coil (36) wound around the fixed portion (34C).