JPS6151508B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an electromagnetic coupling device, and is particularly suitable for electric motors that require frequent stoppages and highly responsive variable speed characteristics, such as electric motors that drive sewing machines. It provides:

BACKGROUND ART Conventionally, so-called clutch motors, which have a friction type clutch and brake that can be stopped frequently, have been widely used to drive sewing machines, that is, industrial sewing machines.

The clutch motor with an automatic needle positioner, which has a fixed position stopping function for the sewing machine needle, that is, a positioning low-speed drive function, rapidly became popular with the advent of the automatic thread trimming function of sewing machines. This greatly contributes to streamlining work.

However, this clutch motor with automatic needle stop device controls the friction clutch and brake.
Since variable speed characteristics are obtained by changing the slip condition of the clutch, it is difficult to determine the optimal values for positioning speed and thread cutting speed in low speed conditions, and the friction material of the clutch is severely worn out in a short period of time. There were defects that required maintenance and inspection.

Therefore, in order to eliminate this drawback and to obtain both functions of better variable speed characteristics with a simple configuration, we developed a sewing machine with a non-contact variable speed motor, that is, an electric motor equipped with an electromagnetic coupling. It has been proposed that the motor be driven by a motor, and is described in US Pat.

However, the electromagnetic joint shown in US Pat. No. 3,910,211 uses a drum as a driving body of the electromagnetic joint by forming a drum on the end face of a flywheel fixed to the rotating shaft of an electric motor, and a void is formed on the inner surface of the drum of this driving body. A magnetic pole having a U-shaped partial cross section, consisting of a magnetic pole piece facing each other through a yoke portion supporting the magnetic pole piece, is fixed to an output shaft to serve as a driven body of an electromagnetic coupling, and is attached to a part of the housing of the motor. A fixed excitation coil is placed within the U-shaped magnetic pole of the driven body with an air gap.

Therefore, compared to a type in which the drum constituting the electromagnetic coupling is fixed to the output shaft and the inductor of the electromagnetic coupling is fixed to the rotating shaft of the motor, this U.S. patent has less inertia on the rotating shaft side. It is believed that the inertia on the output shaft side is smaller than that of the output shaft. but,
As in the above US patent, even if the drum is placed on the rotating shaft side, if the magnetic pole is fixed to the output shaft, this magnetic pole has the function of effectively passing the magnetic flux induced by the excitation coil without loss. Therefore, a predetermined magnetic path cross-sectional area is required, which inevitably results in a large inertial body. Therefore, the inertia on the output shaft side is not so small, and the ratio of the generated torque and inertia of the output shaft (output shaft torque/output shaft inertia) is small, resulting in rapid acceleration and deceleration of about 0.1 to 0.2 seconds. There are drawbacks that make it impractical for applications that require special characteristics, such as electric motors that drive sewing machines.

The present invention aims to eliminate such drawbacks and provide a new and improved electromagnetic coupling device suitable for applications requiring frequent shutdowns and highly responsive variable speed characteristics. The purpose was to arrange the components in a rational and effective manner to increase the inertia ratio between the driving side and the driven side, and to help cool the heat generating parts such as the eddy current generating plate. It is something.

In order to achieve the above object, the present invention includes a magnetic pole body fixed to a rotating shaft and having a U-shaped radial partial cross section;
A driving body of an electromagnetic joint forming a magnetic circuit is formed from a first magnetic path forming body arranged concentrically with a magnetic gap around the outer periphery of the magnetic pole body and fixed to the magnetic pole body; a thin cup-shaped eddy current generating plate having a cylindrical portion inserted into the magnetic gap of the driving body;
This eddy current generating plate is fixed to the output shaft with a boss formed from a thermally conductive material, forming the driven body of the electromagnetic joint, and a disk portion extending in the radial direction of the boss is provided with cooling air as the boss rotates. It has a structure in which a plurality of blades are formed to generate .

The details of this invention will be explained below with reference to the drawings. The drawing is a partially sectional front view of an embodiment of a motor equipped with an electromagnetic coupling device according to the present invention.

In the drawings, reference numeral 1 denotes a housing of an electric motor, which includes a frame 3 that supports a stator 2, a first bracket 7 that supports a bearing 6 on one side of a rotating shaft 5 to which a rotor 4 is fixed, and a first bracket 7 that supports a bearing 6 on the other side of the rotating shaft 5. Bearing 8
It consists of a second bracket 9 that supports the. Reference numeral 10 denotes a driving body for rotating an electromagnetic joint fixed to the end of the rotating shaft 5 that projects outward from the second bracket 9.

This drive body 10 has a horizontal part 15 including a mounting part 14 in the center of which the rotating shaft 5 is inserted and fixed with a keyway 11 and a retaining seat 13 formed by a bolt 12.
A vertical portion 16 protrudes radially from the outer end of the horizontal portion 15, and a first magnetic pole piece 17 protrudes in the axial direction from the tip of the vertical portion 16 in a claw shape along the circumferential direction. The first magnetic pole pieces 17 are arranged so as to mesh with each other alternately with a gap between them, and are formed by a second magnetic pole piece 19 which is integrally fixed to the first magnetic pole piece 17 by a ring 18 made of a non-magnetic material. The magnetic pole body 20 has a U-shaped partial cross section. Also,
The driving body 10 is arranged concentrically with a narrow predetermined gap 21 around the outer peripheries of the magnetic pole pieces 17 and 19, and has a first magnetic pole piece fixed to the second magnetic pole piece 19 by a support 22 made of a non-magnetic material. It has a path forming body 23.

Therefore, the driving body 10 has these magnetic pole bodies 10, the first
The magnetic path forming body 23 and the support 22 form a partial cross section in the shape of a cross, and as a result of including all the magnetic path forming bodies except for a very small number of magnetic path forming bodies described later, the rotating shaft 5 It also functions as a flywheel. And the support 22 made of non-magnetic material
A plurality of ribs 24 are arranged in the circumferential direction to form a ring shape, and this support 22 itself also serves as a blade to flow cooling air in the direction of arrow B.

Reference numeral 25 denotes an excitation coil provided in the space 26 in the magnetic pole body 20 with a predetermined gap, and the coil frame 2
7 and a second magnetic path forming member 28, the magnetic path forming member 28 is located inside the opening 29 of the magnetic pole body 20 to form a magnetic path, and is rotated. Compared to the magnetic path of the driving body 10, the magnetic path is limited to a very small portion, and if a part of the bracket 9 is made to protrude and a fixed magnetic path is formed by this protrusion, it is possible to It can also be omitted.

30 is an output shaft, one of which is supported via a bearing 32 by a third bracket 31 connected to the housing 1, and the other is supported by the magnetic pole body 20.
It is supported by a bearing 34 attached to a cylindrical hole 33 surrounded by a horizontal portion 15. Reference numeral 35 denotes an eddy current generating plate formed by drawing a thin conductive material into a cup shape using a press or the like, and a horizontal portion 36 on the circumferential side (cylindrical portion) of the plate is formed by drawing the thin conductive material into a cup shape.
The bottom vertical portion 37 is connected to a radially extending disk portion 39 of a boss 38 fixed to the output shaft 30 located between the bearings 32 and 34. Eddy current generation plate 3
5 and the boss 38 constitute a driven body 40 of an electromagnetic joint having a U-shaped partial cross section.

A plurality of blades 52 are formed on the disk portion 39 extending in the radial direction of the boss 38 and are arranged radially or spirally to serve as mounting ribs for the movable plate 45 of the electromagnetic brake. The heat generated by the generation plate 35, movable plate 45, etc. is transferred to the blade 5.
The cooling air A generated by the rotation of No. 2 is used to dissipate the air. Note that a plurality of holes 53 are bored in the disk portion 39, and these holes 53 discharge heated air from a space surrounded by the eddy current generating plate 35 and the magnetic pole body 20 whose partial cross section is U-shaped. This serves as a ventilation hole. Furthermore, by forming the boss 38 from a conductive material, it can compensate for the reduction in cross-sectional area due to the thin wall of the eddy current generating plate 35, and also serve as an end ring effect to prevent the generated torque from decreasing. A conductive material such as aluminum or copper has good heat transfer properties and also serves as a heat sink, which together with the blades 52 further enhances the cooling effect.

41 is an electromagnetic brake, and its excitation coil 4
2 is housed inside a yoke 43 which is fixed to the bracket 31 and has a U-shaped partial cross section. 4
4 is a brake lining installed to close the opening of the yoke 43, and 45 is arranged to face the brake lining 44, and is attached to the disk portion 39 of the boss 38 via a thin plate-shaped spring 46. It is a movable plate made of magnetic material. In the electromagnetic brake 41, when the excitation coil 42 is energized and the magnetic flux flows through the yoke 43 to the movable plate 45 made of magnetic material, the movable plate 45 is attracted to the yoke 43 against the force of the spring 46. It is designed to generate braking force. Note that the yoke 43 can be formed directly on the bracket 31 without being provided separately from the bracket 31.

47, 48, 49, 50, 51 are the above-mentioned supports 2
2 is a ventilation hole for flowing the cooling air B generated by the blades formed by the blades from the anti-load side of the motor to the load side as shown by the arrow. The frame 3 and brackets 7, 9, and 31 constituting the housing 1 are provided at appropriate locations for cooling. 5
2 is a mounting leg for mounting the electric motor.

In the above configuration, it is assumed that the rotating shaft 5 of the electric motor is currently rotating with the driving body 10 of the electromagnetic joint that also serves as a flywheel. In this state, when a current is applied to the excitation coil 25 of the electromagnetic joint according to an operator's command, the first magnetic path forming body 23 passes from the first magnetic pole piece 17 of the driving body 10 in the circumferential direction to the second magnetic pole. A magnetic flux is generated along the magnetic path shown by the broken line leading to the piece 19, and the eddy current generating plate 35 of the driven body 40 cuts the magnetic flux. Therefore, an eddy current is generated in the eddy current generating plate 35, and the electromagnetic force is transmitted to the output shaft via the boss 38, and a load connected to the output shaft, such as a sewing machine, is rapidly accelerated and driven. do.

By adjusting the current of the excitation coil 25 in response to a signal from an operator's command, the driven body 4
The torque generated at 0 is adjusted, allowing operation at any predetermined speed.

Furthermore, when the current flowing through the excitation coil 25 is cut off, the force transmitted to the driven body 40 disappears, and when the electromagnetic brake 41 is operated at this time and the movable plate 45 is attracted to the brake lining 44 as described above, the braking force is occurs, and the rotation of the output shaft 30 is rapidly reduced and stopped.

Note that the control of the load connected to the output shaft 30 is as follows:
The explanation will be omitted since it depends on the type of load and is not directly related to this invention, but for example,
If the load is a sewing machine, the above-mentioned U.S. patent no.
It is sufficient to control as shown in No. 3910211.

According to the electromagnetic coupling device of the embodiment having the above configuration, the cup-shaped eddy current generating plate 35 is thin in order to improve responsiveness, but the eddy current generating plate 35 is thin due to the end ring effect of the conductive boss 38. Since the reduction in the cross-sectional area due to the thin wall of 35 can be compensated for, responsiveness can be improved and the generated torque can be prevented from significantly decreasing.

Further, the cup-shaped eddy current generating plate 35 generates heat due to eddy current, but this eddy current generating plate 35 itself is thin, and is made of a thermally conductive material and has blades that generate cooling air as it rotates. Since the heat generated by the eddy current generating plate 35 is fixed to the boss 38, the boss 38 functions as a heat sink, and the heat from the eddy current generating plate 35 is efficiently cooled down.

In addition, by cooling the eddy current generating plate 35 in this way, it is possible to suppress the temperature rise of the movable plate 45 for the electromagnetic brake attached to it, and when the brake is operated, frictional heat is transferred to the movable plate 45 for the electromagnetic brake.
Even if it occurs, it can be efficiently dissipated.

In addition, the eddy current generating plate 35 is cup-shaped and its cylindrical portion is inserted and installed in the narrow gap 21 of the driving body 10, so that the eddy current generating plate 35 does not need to have an increased outer diameter. can be widened, and can generate large torque even with a small diameter.

In the above embodiment, the blades 52 of the boss 38 served as mounting ribs for the movable plate 45 for the electromagnetic brake, and were provided so as to protrude radially or spirally from one surface of the boss 38. does not necessarily have to be as in this embodiment; in short, it is sufficient as long as the cooling air can be generated while the boss 38 is rotating.

As described above, in this invention, the components of the electromagnetic joint are arranged in a rational and effective manner, and the driving body of the electromagnetic joint, which also serves as a flywheel fixed to the rotating side, is a magnetic pole body that constitutes a magnetic circuit. and a magnetic path forming body, and a thin cup-shaped eddy current generating plate disposed in the magnetic gap of the driving body, and a boss fixing this to the output shaft constitute a driven body of the electromagnetic joint. Since the boss is formed with a vane that generates cooling air, the heat generated by the eddy current generating plate can be quickly dissipated and the cooling effect can be enhanced. Because it also serves as a This provides a joint that can withstand the transmission torque and load torque applied to the rotary shaft and prevent a decrease in the speed of the rotating shaft.

Furthermore, according to the present invention, although the cup-shaped eddy current generating plate is thin, the boss for supporting the eddy current generating plate on the output shaft is electrically conductive, so that the end ring effect of this boss is This can compensate for the reduction in cross-sectional area due to thinning of the eddy current generating plate, and can prevent a significant decrease in the generated torque.

In addition, the eddy current generation plate is cup-shaped and its cylindrical part is inserted into the narrow gap of the driver, so the eddy current generation area can be widened without increasing the outer diameter of the eddy current generation plate. This makes it possible to increase the ratio of generated torque to diameter (outer diameter) compared to conventional flat eddy current generating plates.

Therefore, for the above reasons, the present invention can provide an electromagnetic coupling device that is most suitable for electric motors that require frequent stoppages and highly responsive variable speed characteristics, such as electric motors that drive sewing machines. .

As explained in the example, if a movable plate facing the yoke of the electromagnetic brake is attached to the boss, a separate part for attaching the movable plate of the electromagnetic brake can be omitted, and the axial dimension can be shortened. At the same time, the boss functions as a heat sink to dissipate frictional heat generated during brake operation from the movable plate, thereby making it possible to extend the wear life of the movable plate.

[Brief explanation of the drawing]

The figure is a partially sectional front view of an embodiment of a motor equipped with an electromagnetic coupling device according to the present invention. In the figure, 5 is the rotating shaft of the electric motor, 10 is the driver of the electromagnetic joint, 17 and 19 are the magnetic pole pieces, 20 is the magnetic pole body, 2
3 and 28 are magnetic path forming bodies, 30 is an output shaft, 35 is an eddy current generating plate, 38 is a boss, 40 is a follower of an electromagnetic joint, 41 is an electromagnetic brake, 45 is a movable plate, 52 is a blade, and 53 is a hole It is.

Claims (1)

[Claims] 1. A magnetic pole body fixed to a rotating shaft and having a U-shaped radial partial cross section, and a first magnetic pole body arranged concentrically with a magnetic gap around the outer periphery of the magnetic pole body and fixed to the magnetic pole body.
A thin cup-shaped eddy current generating plate that forms a driving body of an electromagnetic joint that forms a magnetic circuit with a magnetic path forming body, and a thin cup-shaped eddy current generating plate that has a cylindrical part inserted into the magnetic gap of this driving body; A boss formed from a thermally conductive material that fixes the current generating plate to the output shaft forms the driven body of the electromagnetic joint, and a disk portion extending in the radial direction of the boss generates cooling air as the boss rotates. An electromagnetic coupling device with multiple blades. 2. The boss is formed to attach a movable plate facing the yoke of the electromagnetic brake. Claim 1
Electromagnetic coupling device described in Section 1. 3. The electromagnetic coupling device according to claim 1, wherein the boss is made of aluminum or copper.