JPH10174422A - Electric actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric actuator which can cut off transmission of power or torque promptly using a magnetic coupling. SOLUTION: This electric actuator is provided with a motor 2, a torque- transmitting mechanism for transmitting rotational torque from the motor 2 to load, and a torque cut-off mechanism which is built in the torque-transmitting mechanism and cuts off the transmission of rotational torque to the load. A magnetic coupling 15 is used as the torque cut-off mechanism. When the torque applied from the load to an output shaft 6 becomes larger than the step-out torque of the magnetic coupling 15, the magnetic coupling 15 turns into a power swing condition, to cut off the transmission of the rotational torque to the load. When the magnetic coupling 15 turns into a step-out condition, relative rotation occurs between magnetic coupling members 13, 14, voltage is induced at a search coil 18, and the voltage is outputted as a stop signal via a rotary transformer 19. From the stop signal, it is thus possible to stop supplying armature current to the motor 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric actuator, and more particularly to an electric actuator suitable for use in a part for generating a power for a feeding motion or a rotating motion in an automatic power saving apparatus such as an assembly robot. The present invention relates to an actuator, and more particularly, to an electric actuator having a power generation device such as a rotary servomotor or a linear servomotor having a protection function for a load mechanism.

[0002]

2. Description of the Related Art In an automatic labor-saving device such as an assembly robot, an electric actuator having a servomotor mainly utilizing an electromagnetic phenomenon as a power generation device is used as a power source for translational motion and rotational motion. A drive system including the electric actuator and its control device needs to be provided with a protection function for stopping the generation of power or the transmission of power when a failure occurs in a motion mechanism unit loaded on the electric actuator. In particular, to prevent the occurrence of personal injury due to assembly robots, etc., and to minimize the troubles that occur in the motion mechanism, the drive system of the electric actuator and the entire automatic power saving device must be designed to be fail-safe. Must.

Conventionally, in order to prevent the above danger, an overcurrent flowing through an armature such as a servomotor used as a power generation device of an electric actuator is detected, and an approach of an obstacle is detected by a sensor. The occurrence of an abnormality is detected by such means. When the occurrence of an abnormality is detected, power generation and power transmission of the electric actuator are stopped by software control using a computer provided in the drive system. As another countermeasure, a dead space is provided around an automatic labor-saving device such as an assembling robot, and safety is ensured by isolating the robot from humans.

Further, conventionally, a torque transmission device with a torque limiter for the purpose of installation between an electric actuator and a load [Japanese Patent Application No. 5-275194 (Japanese Unexamined Patent Application Publication No.
Japanese Patent Application No. 5-296184 (JP-A-7-154957)].

[0005]

As described above, when the generation of power of the electric actuator and the transmission of power are stopped by software control when an abnormality occurs, a circuit configuration for detecting the abnormality and processing the signal thereof is provided. In addition, the control algorithm of the software becomes complicated, and further, there is a problem that the reliability is reduced with the complexity.

Providing a dead space around the automatic labor-saving device adversely affects the space-saving design of the production line.

[0007] Further, installing a torque transmission device with a torque limiter between the actuator and the load adversely affects the miniaturization design of an automatic power saving device and the like.

An object of the present invention is to provide an electric actuator capable of interrupting the transmission of power (or torque) by hardware in a finite time when an abnormality occurs.

Another object of the present invention is to provide an electric actuator which can shut off transmission of power (or torque) within a finite time by a hardware having a simple structure when an abnormality occurs.

It is still another object of the present invention to provide an electric actuator which can rapidly cut off transmission of power (or torque) using a magnetic coupling and without controlling an exciting current when an abnormality occurs. It is in.

Another object of the present invention is to provide an electric actuator with higher safety by interrupting the transmission of power (or torque) and also stopping the supply of electric energy to the power generator. is there.

Another object of the present invention is to provide an electric actuator capable of detecting out-of-step of a magnetic coupling with a simple structure and outputting a stop signal for instructing a stop of supply of electric energy to a power generating device. It is in.

More specifically, according to the present invention, the transmission of the power (torque) and the interruption of the power (torque) within a finite time are performed by a hardware mechanism provided inside the electric actuator, not by software control. Can be performed,
It is an object of the present invention to provide an intrinsically safe electric actuator suitable for a fail-safe design and a compact and lightweight design of a system.

[0014]

SUMMARY OF THE INVENTION The present invention provides a power generating apparatus for generating power by converting electric energy into kinetic energy, a power transmitting mechanism for transmitting power to a load, and a power transmitting mechanism incorporated in the power transmitting mechanism. The present invention is directed to an electric actuator including a power cutoff mechanism (or torque cutoff mechanism) that blocks transmission of (or torque) to a load. As the power generation device, a rotary motor such as a servomotor or a non-rotary motor such as a linear motor can be used. In particular, when the power generation device, the power transmission mechanism, and the power cutoff mechanism are configured as one unit (one product),
In addition to being easy to handle, the overall shape can be made compact.

In the present invention, as a power cutoff mechanism (or torque cutoff mechanism), when a force (or torque) received from the load becomes larger than a predetermined upper limit without detecting a change in the load, the power to the load is reduced. Transmission (or torque)
That is configured to cut off. When such a configuration is adopted, when a load (movement mechanism) driven by the electric actuator collides with an object, the detection is not performed and the software control of the electric actuator is not performed. Power transmission to the load can be interrupted.

The above-described power cut-off mechanism (or torque cut-off mechanism) includes a drive side member to which power (or torque) is directly transmitted and a drive side member connected to the drive side member by a magnetic coupling utilizing magnetic attraction. A driven side member for transmitting power (or torque); and a magnetic attraction force generating means provided at at least one of the drive side member and the driven side member to generate a magnetic attraction force. When the force (or torque) applied from the load is greater than the coupling force (escape torque) of the magnetic coupling, the magnetic coupling is out of step and the transmission of power (or torque) to the load is cut off. What was done can be used. When the mechanism of power (or torque) transmission and power (or torque) interruption is constituted by a magnetic coupling in this way, the interruption of power (or torque) transmission utilizes the step-out phenomenon inherent in the magnetic coupling unit. Therefore, power (or torque) transmission can be interrupted instantaneously, and the occurrence of an abnormality can be promptly dealt with.

The magnetic attraction force generating means may be an electromagnetic coil. However, if an electromagnetic coil is used, a circuit for supplying an exciting current is required, and the structure becomes complicated. In addition, an induced current flows in the electromagnetic coil during step-out, increasing the escape torque and increasing the duration of the force. Therefore, it is preferable that the magnetic attraction force generating means is constituted by permanent magnets provided on the drive-side member and the driven-side member such that a plurality of magnetic poles are formed on the opposing surfaces of the drive-side member and the driven-side member. When a permanent magnet is used, it is not necessary to supply an exciting current, so that the structure is simplified. Further, when a plurality of slits or grooves are formed on the pole face of the permanent magnet, generation of eddy current on the surface of the permanent magnet during step-out can be suppressed, and an increase in escape torque can be reduced.

In a case where a plurality of magnetic poles are arranged along the moving direction of the driving member in the electromagnetic coupling, the magnetic pole size of each magnetic pole in the moving direction is determined by the load applied to the magnetic coupling until the magnetic coupling is out of synchronization. Preferably, the product of the applied force and its duration is determined so as to fall within a predetermined safety region depending on the load. That is, it is preferable that the time required for the magnetic coupling to reach the step-out state falls within the time required for ensuring safety (finite time defined as safe). In this case, by appropriately setting the magnetic pole dimensions, the time until the step-out occurs can be arbitrarily set, and the safety in the event of a load collision can be ensured. When a permanent magnet is used, the size of the permanent magnet constituting each magnetic pole in the moving direction may be appropriately determined.

Further, a shut-off operation detecting means for detecting a shut-off operation of the power (or torque) in the power cut-off mechanism (torque cut-off mechanism) and outputting a stop signal, and an electric signal to the power generating device when the stop signal is inputted. Electric energy supply stopping means for stopping the supply of energy may be further provided.
In addition, without providing the cutoff operation detecting means and the electric energy supply stop means, the electric energy supply cutoff means for directly cutting off the supply of the electric energy to the power generation device in synchronization with the power cutoff operation of the power cutoff mechanism is provided. Is also good. When these means are provided, the electric energy supplied to the power generation device of the electric actuator can be stopped or cut off in synchronization with the step-out of the magnetic coupling, and the electric actuator can be stopped quickly. In addition, it is possible to prevent the electric actuator from operating again without removing the cause of the abnormality.

The present invention will be described with respect to a case where an electric motor having a rotating shaft is used as a power generating device.
An electric motor having a rotating shaft, a torque transmitting mechanism for transmitting the rotating torque of the rotating shaft to the load, and a torque interrupting mechanism (power interrupting mechanism) incorporated in the torque transmitting mechanism for interrupting the transmission of the rotating torque to the load. Should be provided. The torque cut-off mechanism is connected to the driving-side rotating member that is driven directly by the rotating torque and rotates, and the driven-side rotating member that is connected to the driving-side rotating member by a magnetic coupling that uses magnetic attraction to transmit the rotating torque to the load. A magnetic attraction force generating means provided on at least one of the driving side rotating member and the driven side rotating member to generate a magnetic attraction force, wherein a torque applied from a load to the driven side rotating member is magnetically coupled. When the escape torque exceeds the escape torque, the magnetic coupling enters a step-out state and the transmission of the rotational torque to the load is interrupted.

In this case as well, a cut-off operation detecting means for detecting an operation of cutting off the transmission of torque in the torque cut-off mechanism and outputting a stop signal, and stopping supply of electric energy to the motor when the stop signal is inputted. Needless to say, an electric energy supply stopping means may be further provided. In this case, the cut-off operation detecting means includes a conductive driving-side slip ring disposed concentrically with the driving-side rotating member on the driving-side rotating member, and a driven-side rotating member concentric with the driven-side rotating member. A driven side slip ring having a conductive property, and a drive side slip ring disposed between the drive side slip ring and the driven side slip ring so that when the magnetic coupling is in a coupled state, the drive side slip ring is disposed. An electrical connection mechanism that electrically connects the slip ring and the slip ring on the driven side and cuts off the electrical connection between the two when the magnetic coupling is out of synchronization, and is attached to a non-rotating portion such as a motor case. And at least one pair of sliding contacts that are always in contact with the driving side slip ring and the driven side slip ring. The electrical connection mechanism is fixed to the driving side slip ring and the driven side slip ring, respectively, and electrically connects the driving side slip ring and the driven side slip ring when the magnetic coupling is in a coupled state. Thus, at least one pair of spring contacts that contact each other and cut off the electrical connection between the two when the magnetic coupling is out of step. The pair of spring contacts are provided so as not to hinder the current collecting operation of the pair of sliding contacts.

By directly utilizing the structure of the interruption operation detecting means using the above-mentioned two slip rings, the supply of the armature current to the electric motor is directly interrupted when the magnetic coupling is out of synchronization. Can be. Specifically, in the case of a single-phase motor, an armature current is supplied to an armature winding of the motor through at least a pair of sliding contacts. With this configuration, when the magnetic coupling is out of synchronization, the pair of spring contacts are in a non-contact state, so that the supply of the armature current to the electric motor can be directly and immediately interrupted. When the motor is a multi-phase (n-phase) motor, n sets of structures of the slip ring, the sliding contact, and the contact spring on the driving side and the driven side are prepared corresponding to the multi-phase armature windings. Thus, an armature current may be supplied to the n-phase armature windings through these sets of sliding contacts.

The breaking operation detecting means may have any structure as long as it can detect that the breaking operation has been performed. In an example of the shut-off operation detecting means, for example, the induced voltage is generated by a change in magnetic flux generated from magnetic force generating means provided on one of the driving side member and the driven side member and provided on the other of the driving side member and the driven side member. Is used. In this case, the electric energy supply stopping means may be configured to operate using the induced voltage induced in the search coil as a stop signal. When the magnetic coupling is out of step, relative rotation occurs between the driving side member and the driven side member. Therefore, by providing a search coil on one of the driving side member and the driven side member,
A voltage is induced in the search coil at the same time as step-out occurs.
By using the search coil as described above, the occurrence of step-out can be detected reliably and easily.

The induced voltage induced in the search coil may be output by a brush structure, but it is preferable to use a rotary transformer in consideration of the life. When a rotary transformer is used, the primary winding may be provided on one of the driving side member and the driven side member provided with the search coil, and the secondary winding may be provided on the non-rotating portion. In this way, the voltage induced in the search coil can be taken out in a non-contact manner.

[0025]

Embodiments of the present invention will be described below in detail with reference to the drawings.

First, as an example of the first embodiment of the present invention, an electric actuator using a rotating electric machine as a power generation device that converts electric energy into kinetic energy and generates power will be described. FIG. 1 is a structural view showing a part of the electric actuator 1 in cross section. The electric actuator 1 includes an electric motor 2 as a power generation device, a sensor unit 3, and a power transmission unit 4 that transmits power (or rotational torque) output from a rotating shaft of the electric motor to a load. Various motors such as a DC motor, a synchronous motor, and an induction motor can be used as the motor used here. The sensor unit 3 is a detection device (for example, an encoder or the like) that configures a speed sensor and a position sensor used to operate the electric motor 2 as a servomotor.
It is comprised including.

The power transmission unit 4 is provided with a housing 2 of the electric motor 2.
The main part of the power transmission mechanism (or the torque transmission mechanism) is housed inside a casing 5 attached to the end of “a”. End 5 of casing 5 on electric motor 2 side
The rotary shaft 2b of the electric motor 2 is inserted and arranged inside a. A bearing 7 for rotatably supporting the output shaft 6 is provided on an inner peripheral portion of the end 5 b of the casing 5 on the non-motor 2 side.
Are fitted and fixed. The rotating shaft 2b of the electric motor 2 and the output shaft 6 are arranged side by side so that their axes coincide with each other, and the end of the rotating shaft 2b and the inner end 6a of the output shaft 6 are separated by a slight gap G. Are facing each other. A load is attached to the outer end 6b of the output shaft 6.

A permanent magnet support 8 integrally formed of a non-magnetic material is fixed to the rotating shaft 2b. The permanent magnet support 8 has a first cylindrical portion 8a fitted and fixed to the outer periphery of the rotating shaft 2b, and a plate-like annular shape extending radially outward from one end of the first cylindrical portion 8a. It comprises a portion 8b and a second cylindrical portion 8c extending from the radially outer end of the annular portion 8b in the axial direction of the rotating shaft 2b. An annular yoke 9 integrally formed of a magnetic material is fitted and fixed to the inner peripheral portion of the second cylindrical portion 8c. A plurality of permanent magnets 10 are fixed on the inner peripheral surface of the annular yoke 9. An annular permanent magnet support 11 made of a magnetic conductive material is fitted on the outer periphery of the inner end 6 a of the output shaft 6, and a plurality of permanent magnets 12 are mounted on the outer peripheral surface of the permanent magnet support 11. ... is fixed.

In this example, the drive member to which power (or torque) is directly transmitted from the rotating shaft 2b is constituted by the permanent magnet support 8 and the annular yoke 9, and the permanent magnet support 8
, The annular yoke 9 and the permanent magnets 10 form a first magnetic coupling member 13 (FIG. 2). Further, a driven-side member that transmits power (or torque) to a load by being connected to a driving-side member by a magnetic coupling utilizing magnetic attraction by the permanent magnet support 11 is configured. .. Constitute a second magnetic coupling member 14. The permanent magnets 10 and 12 constitute magnetic attraction force generating means for generating a magnetic attraction force. Also, the first and second magnetic coupling members 13 and 14 constitute a magnetic coupling constituting a power cutoff mechanism (or torque cutoff mechanism) for blocking transmission of power (or torque) from the electric motor 2 to the load. 15 are constituted.

When a force (or torque) applied from a load (not shown) to the output shaft 6 constituting the driven member becomes larger than a coupling force (escape torque) of the magnetic coupling, the magnetic coupling 15 becomes magnetic. The coupling 15 is brought out of step and the transmission of power (or torque) to the load via the output shaft 6 is blocked. In this example, the arrangement of the permanent magnets 10 and the permanent magnets 12 is as shown in FIG. 2 so as to effectively exert such a function. The permanent magnets 10 and the permanent magnets 12 are 2
A plurality of grouped magnets configured by arranging two permanent magnets adjacent to each other are attached so as to be arranged at a constant interval in the circumferential direction. This constant interval is easy when the magnetic coupling 15 is out of step and relative rotation occurs between the first magnetic coupling member 13 and the second magnetic coupling member 14. To prevent re-coupling. The two permanent magnets that are adjacent to each other and that constitute the group magnet are a combination of an N pole and an S pole. A plurality of magnets composed of permanent magnets 10 fixed to an annular yoke 9 and a permanent magnet 12 fixed to a permanent magnet support 11
Are arranged so as to attract each other in the coupling state. In addition, the magnetic pole width dimension (circumferential dimension, that is, the dimension in the rotating direction of the rotating shaft 2b) of the permanent magnets 10 and the permanent magnets 12 is such that the force applied from the load to the output shaft 6 is smaller than the coupling force of the magnetic coupling 15. It is set so that the magnetic coupling 15 immediately goes out of synchronization when it becomes larger. More specifically, regarding the magnetic pole width dimensions of the permanent magnets 10 and the permanent magnets 12, the product of the force applied to the load and the duration thereof before the magnetic coupling reaches the step-out state is determined in advance according to the load. Determine to be within the defined safety area. That is, the magnetic pole width dimension is determined so that the time until the magnetic coupling reaches the step-out state falls within the time required for ensuring safety (finite time determined to be safe). This will be described later.

The magnetic coupling 15 essentially has the function of transmitting the power generated by the electric motor 2 to the output shaft 6 and blocking the power.

Next, referring to FIG.
The operation of power transmission and cutoff of the motor will be described in detail. FIG. 3 shows permanent magnets 10 constituting the magnetic coupling shown in FIG.
, And 12 are radially cross-sectional views of one set magnet, that is, one pole pair, developed in the circumferential direction. The output shaft 6 via the first and second magnetic coupling members 13 and 14;
(The torque Tc transmitted to 73 is expressed as follows based on the principle of virtual displacement.

Tc = − (δWg / δθ) (1) Wg = (Vg / 4πμo) ∫ (Bg) ² dθ (2) where Wg is the magnetic energy stored in the gap 16 and θ is the circumference Vg is the total volume of the air gap 16, Bg is the magnetic flux density of the air gap 16, μo
Is the vacuum permeability. Here, considering the torque due to the fundamental wave component of the magnetic flux density Bg of the air gap, the torque Tc transmitted to the output shaft 6 is expressed as Tc = Tpo sin (pθ) (3). In equation (3), p is the number of pole pairs of the permanent magnets 10 and 12 (that is, one of the magnetic coupling members 13 or 1).
4), and Tpo is the maximum value of the transmission torque. The amplitude of this torque Tc is called the escape torque of the magnetic coupling 15.

If the relationship Tpo> T _L (4) is satisfied between the escape torque Tpo of the magnetic coupling 15 and the load torque _TL applied to the output shaft 6, the rotation of the electric motor 2 is performed. Shaft 2b
(Rotational torque) is transmitted to the output shaft 6 via the magnetic coupling 15. On the other hand, if the relationship Tpo <T _L (5) is satisfied, the magnetic coupling 15
Is out of synchronism, and the power (rotation torque) from the rotating shaft 2 b of the electric motor 2 cannot be transmitted to the output shaft 6.
That is, when a load torque having a magnitude exceeding the value of the escape torque set based on the equations (1), (2) and (3) is applied to the output shaft 6, the power from the electric motor 2 to the output shaft 6 is increased. Transmission is blocked.

FIG. 4A shows the relationship between the relative angular displacement θ of the first and second magnetic coupling members 13 and 14 and the torque Tc calculated for this example. As is apparent from the equation (3), the maximum value of the torque Tc, that is, the escape torque occurs at an angular displacement of θ = ± π / (2p) (6). If an excessive load torque is applied to the output shaft 6, it is desirable that the power be cut off within a short time within a finite time defined as safe. Therefore, the angular displacement expressed by the equation (6) is smaller. Is good. Therefore, the permanent magnet 1 is attached to the first and second magnetic coupling members 13 and 14.
The plurality of magnetic poles constituted by 0 and 12 are preferably constituted by multi-pole permanent magnets having a small magnetic pole width dimension (circumferential dimension).

As shown in FIG. 4B, the magnetic pole width dimension is τ.
Assuming that the inner diameter of the air gap of the magnetic coupling is D, there is a relationship between them as follows: τ = πD / (2p) (7)

Now, the angular displacement θ expressed by the equation (6) is calculated by the following equation (6).
When expressed using the equation and the equation (7), it is expressed as follows: θ = τ / D (8)

FIG. 4C shows a time change of the force F generated when the mechanism (load) driven by the torque Tc transmitted by the magnetic coupling collides with a certain object. Here, in general, when the maximum value of the force F is constant, the impulse (F × Δt) is smaller as the duration Δt is shorter. Further, under a certain load condition, the time t until the magnetic coupling steps out has a positive correlation with the angular displacement θ until the step-out occurs. Therefore, in order to shorten the time t until the step-out occurs, the angular displacement θ represented by the equation (8) may be reduced. As is apparent from the equation (8), in order to reduce the angular displacement θ, it is necessary to reduce the magnetic pole width dimension τ of the magnetic coupling and design the gap inner diameter D to be large. When the inner diameter D of the gap is increased, the overall size of the apparatus is increased. Therefore, it is preferable to reduce the magnetic pole width τ and the angular displacement θ to shorten the time t until the step-out occurs.

FIG. 4D shows the escape torque characteristics of the electric actuator having a built-in magnetic coupling. As can be seen from the figure, assuming that the same force F1 is applied as the magnetic pole width dimension τ increases (τ1 <τ2 <τ3), the duration t1 increases, and the impulse (F1 × t1
) Increases. For example, when force F1 is applied,
In order to keep the duration within t1, τ1 should be selected as the magnetic pole width dimension τ. In this case, the characteristic curve of the magnetic pole width τ1 in FIG.
The area inside the area is a safety area, and the area outside the area is a danger area. This means that the magnetic pole width dimension τ may be determined so that the impulse falls within the safety region of the safety curve.

If the magnetic poles are constituted by multi-pole permanent magnets, the first and second magnetic coupling members 13 and 14
Torsional rigidity is also improved. Further, by using a permanent magnet having a small magnetic pole width, an increase in escape torque due to an eddy current generated at the time of step-out can be reduced. As shown in FIG. 5, even if a plurality of slits or grooves S are formed on the magnetic pole surface of the permanent magnet M, generation of eddy current on the magnetic pole surface can be suppressed. Note that the plurality of magnetic poles of the magnetic coupling 15 may be configured by multi-pole electromagnets. However, in this case, the size of the magnetic coupling increases, and an induced current flows through the electromagnetic coil of the electromagnet at the time of step-out, so that the escape torque increases and the duration of the force increases. Therefore, it is preferable to configure the multi-pole permanent magnet.

Returning to FIG. 1, a search coil 18 is attached to at least one permanent magnet 12 of the second magnetic coupling member 14 so as to surround the outside. The search coil 18 is wound around one or more permanent magnets 12 so as to be spatially orthogonal to the magnetic flux generated from the permanent magnets 10 of the first magnetic coupling member 13. A primary winding unit 19a of a rotary transformer 19 having a primary winding W1 connected in series to a search coil 18 is fixed to the output shaft 6 adjacent to the magnetic coupling 15.
The primary winding unit 19a has a structure in which the winding conductor of the primary winding W1 is wound around an annular insulating resin bobbin fitted to the output shaft 6. The secondary winding unit 19 b of the rotary transformer 19 is attached to the casing 5. The secondary winding unit 19b is
Is fixed to the casing 5 via a fitting 20 screwed to the inner wall of the casing 5. Secondary winding unit 19
b is an annular insulating resin bobbin configured to surround the primary winding unit 19a from the circumferential direction, and the primary winding W
1 has a structure in which the secondary winding W2 is wound so as to link the magnetic flux generated from the secondary winding W1. In this example, the search coil 18 and the rotating transformer 19 form the magnetic coupling 15.
Of the power (or torque) in step (1) and outputs a stop signal.
The output lead wire of the secondary winding W2 of the rotary transformer 19 is drawn out of the casing 5 through a through hole 21 provided on the outer periphery of the casing 5.

The signal output from the output lead wire of the secondary winding W2 is input to a control device (not shown) of the electric motor 2 as a stop signal. The control device is provided with electric energy supply stopping means for stopping the supply of electric energy to the electric motor 2 when receiving the stop signal. This electric energy supply stopping means is provided inside the electric motor 2 when the electric motor 2 itself has a built-in control device. The electric energy supply stop means is provided with a controllable switch in the middle of a circuit for flowing the armature current to the electric motor 2, and opens the switch in response to the input of the stop signal to stop the supply of the armature current. Can be configured.

Next, the operation of the search coil 18 and the rotary transformer 19 will be described with reference to FIG. FIG. 6 is an equivalent circuit of the primary winding W1 and the secondary winding W2 of the search coil 18 and the rotary transformer 19. Under the load condition that satisfies the above expression (4), the first and second magnetic coupling members 13 and 14 of the magnetic coupling 15 attract each other by the magnetic attractive force and rotate synchronously. No magnetic flux that changes in linkage with the coil 18 is generated. Therefore, no voltage is induced in the search coil 18. Then, the load condition that satisfies the above expression (5), that is, the magnetic coupling 15 is out of synchronization, and relative rotation occurs between the first and second magnetic coupling members 13 and 14. Then, a relative angular velocity is generated between the two, and the magnetic flux emitted from the permanent magnets 10 interlinks the search coil 18 while changing. As a result, an induced voltage is generated in the search coil 18. This induced voltage causes a current to flow through the primary winding W1 of the rotary transformer 19, and the magnetic flux generated by this current interlinks with the secondary winding W2, and a voltage appears at both ends of the secondary winding. This voltage becomes the stop signal. Thus, the rotating shaft 2 of the electric motor 2
The stop signal can be taken out of the motor 2 in synchronization with the interruption of the power transmission between the motor b and the output shaft 6.

As described above, when the electric motor 2 for converting electric energy to kinetic energy and the mechanism for transmitting or interrupting the power to the output shaft 6 are constituted by the multipolar magnetic coupling 15, the magnetic coupling 15 is set. The torque exceeding the escape torque is not transmitted to the output shaft 6. Further, a mechanism for generating a signal in synchronization with the cutoff of the power transmission is constituted by the search coil 18 and the rotary transformer 19, so that a signal generated in synchronization with the cutoff of the power transmission is supplied to the electric motor 2. It is possible to cut off the electrical energy that is generated.

FIG. 7 shows an example of a torque characteristic and a measured value of a force generated on the load side when a load is attached to an output shaft using the electric actuator of this embodiment and an object collides with the load. In FIG. 7, a curve a indicates a change in torque at the time of collision, and a curve b indicates a change in force generated on the load side. It can be seen that the transmission torque from the rotating shaft 2b to the output shaft 6 is limited by the escape torque of the magnetic coupling 15, and the resulting force on the load side is also limited. Further, in this example, since the width of the permanent magnets 10... And 12 of the magnetic coupling 15 is reduced to form a multipolar structure, it is confirmed that the duration of the impact force is as short as about 40 msec.

Next, another embodiment of the present invention will be described. FIG. 8 shows an electric actuator 1 to which the present invention is applied.
FIG. 2 is a structural view showing a part of the cross section of FIG. This example also includes an electric motor 102, a sensor unit 103 (inside is omitted in FIG. 8), and a power transmission unit 104 as a power generation device, as in the example of FIG. In this example, unlike the example of FIG. 1, the rotation shaft of the electric motor 102 and the output shaft 106 are integrated. Bracket 1 on both sides of motor 102
05a and 105b are attached. A bearing 107 for supporting the output shaft 106 is fixed to each of the two brackets 105a and 105b.

The motor 102 is a permanent magnet synchronous motor having an armature core 102a and an armature winding 102b on the stator side and a field magnet 102c on the rotor side. The above-mentioned brackets 105a and 105b are provided with the armature core 1
02a. And armature winding 10
2b is appropriately wound around a salient pole provided on the inner peripheral side of the armature core 102a. The rotor includes a pair of oilless metals 109 rotatably fitted to an output shaft 106 used as a rotating shaft, and a pair of oilless metals 109.
9 includes a permanent magnet support 108 formed by insert molding, and a field magnet 102c composed of a plurality of permanent magnets supported by the permanent magnet support 108. The oilless metal 109 is a bearing that does not require lubrication.

The permanent magnet support 108 has a first cylindrical portion 108a to which the oilless metal 109 is fixed, and a part of the output shaft 106 provided integrally with one end of the first cylindrical portion 108a. And a second cylindrical portion 108b extending in the axial direction so as to surround the periphery of the second cylindrical portion 108b. 2nd cylindrical part 1
A plurality of permanent magnets 110 constituting a plurality of magnetic poles are fixed to the inner peripheral portion of 08b so as to be arranged in the circumferential direction. Further, an annular permanent magnet support 111 having a plurality of permanent magnets 112 constituting a plurality of magnetic poles on the outer periphery is fixed to the output shaft 106. The permanent magnet support 111 is fixed to the output shaft 106 via an annular boss. The permanent magnet support 111 integrally includes a first portion 111a to which the plurality of permanent magnets 112 are fixed, and a second portion 111b having a larger diameter than the first portion 111a. The arrangement of the permanent magnets 110 and 112 fixed to the permanent magnet supports 108 and 111 is the same as that of the permanent magnets 10 and 12 of the first embodiment shown in FIGS. .

In this example, the permanent magnet support 108
A drive-side member to which power (or torque) is directly transmitted from the electric motor 102 is configured, and the first magnetic coupling member 11 is constituted by the permanent magnet support 108 and the permanent magnets 110.
3 are configured. Further, a driven-side member that transmits power (or torque) to a load by being connected to a driving-side member by a magnetic coupling 115 by the permanent-magnet support 111 is configured, and the permanent-magnet support 111 and the permanent magnets 112. Two magnetic coupling members 114 are configured. And by the permanent magnets 110 ... and 112 ...
Magnetic attraction force generating means for generating a magnetic attraction force is configured. Further, the first and second magnetic coupling members 113 and 114 constitute a magnetic coupling constituting a power cutoff mechanism (or torque cutoff mechanism) for blocking transmission of power (or torque) from the electric motor 102 to the load. 115 are configured.

The power (torque) generated by the electric motor 102 is transmitted to the output shaft 106 via the magnetic coupling 115, and exceeds the escape torque of the magnetic coupling 115, as described in detail in the first example. Power (torque) is shut off.

In the electric actuator shown in FIG. 8, the cutoff operation detecting means for detecting the operation of cutting off the transmission of torque in the power cutoff mechanism and outputting a stop signal includes first and second conductive slip members. Ring (driving side slip ring and driven side slip ring) 116
117 and first and second spring contacts 118 and 119
And sliding contact structures 120 and 121 having first and second sliding contacts 120a and 121a.

The first slip ring 116 is output on the outer periphery of the second cylindrical portion 108b of the permanent magnet support 108 constituting the drive-side rotating member via an annular insulating ring 122 made of an insulating material. It is arranged concentrically with the shaft 106. The second slip ring 117 is disposed on the outer periphery of the second portion 111b of the permanent magnet support 111 constituting the driven-side rotating member so as to be concentric with the output shaft 106 via the insulating ring 123. I have. The first and second spring contacts 118 and 119 are fixed to opposing end surfaces of the first slip ring 116 and the second slip ring 117, respectively. First and second spring contacts 118
And 119 electrically connect the first slip ring 116 and the second slip ring 117 when the magnetic coupling 115 is in the coupled state, and
An electrical connection mechanism for interrupting the electrical connection between the two when the step 15 goes out of synchronization is configured.

The sliding contact structures 120 and 121 are mounted on the bracket 105a. Sliding contact structure 12
0 and 121 are a pair of sliding contacts 120a and 121a which are always in contact with the first and second slip rings 116 and 117, respectively, and a sliding contact 120.
a and 121a, which are made of an insulating material and are accommodated movably in the radial direction of the output shaft 106, and are disposed inside the contact housings 120b and 121b, and are provided with sliding contacts 120a and 121a. , And a terminal portion (not shown) electrically connected to the sliding contacts 120a and 121a.

FIG. 9 shows slip rings 116 and 11
7 schematically shows a positional relationship among spring contacts 118 and 119 and sliding contacts 120a and 121a. The sliding contacts 120a and 121a are respectively connected to the slip ring 1
The outer peripheral surfaces of 16 and 117 are slid in the circumferential direction. Spring contacts 118 and 119 are fixed to slip rings 116 and 117, respectively. When the first and second magnetic coupling members 113 and 114 of the magnetic coupling 115 are rotating synchronously, the spring contacts 118 and 119 are in contact, and the first and second magnetic coupling members 1
13 and 114 are electrically connected to each other. When the magnetic coupling is out of synchronization and relative rotation occurs between the first and second magnetic coupling members 113 and 114, the spring contacts 118 and 119 are instantaneously provided.
Becomes non-contact. If the relative rotation between the first and second magnetic coupling members 113 and 114 is one or more, the spring contacts 118 and 119 repeat contact and non-contact. A pair of sliding contacts 120a and 121a, which are in constant contact with the first and second slip rings 116 and 117, are connected to the positive and negative outputs of the DC power supply. By doing so, during power transmission, the sliding contact 120a-slip ring 11
6-spring contact 118-spring contact 119-slip ring 117-sliding contact 121a. On the other hand, if the power transmission is interrupted due to the step-out state of the magnetic coupling 115, the above-mentioned circuit is disconnected at the spring contacts 118 and 119, and a continuous current does not flow through this circuit. In this example,
The stop or intermittent supply of this current is used as a stop signal.

In this example, the permanent magnet support 1 constituting a part of the rotor of the electric motor 102 with respect to the output shaft 106
08 is rotatably supported by the oilless metal 109, so that the magnetic coupling 115 is in the coupled state, and the first and second magnetic coupling members 113 and 1
When the motor 14 rotates synchronously, the output shaft 106 and the rotor (permanent magnet support 108) rotate synchronously. However, when the magnetic coupling 115 is out of step, at least the permanent magnet support 108 rotates around the output shaft 106 and a relative displacement occurs between the two. When the supply of the armature current to the electric motor 102 is stopped by operating the electric energy supply stopping means (not shown) using the above-mentioned stop signal, the electric motor 102 is stopped.

By utilizing the above structure, it is possible to directly cut off the armature current flowing through the armature winding 102b of the motor 102 when the electromagnetic coupling 115 is out of step. That is, the sliding contact 120a-slip ring 116-spring contact 118-spring contact 119-
An armature current is supplied to the armature winding 102b of the electric motor 102 through a circuit composed of the slip ring 117 and the sliding contact 121a. In this way, the magnetic coupling 115 is out of synchronization, and when relative rotation occurs between the magnetic coupling members 113 and 114, the spring contacts 118 and 119 become non-contact in synchronization with the out of synchronization. Therefore, the armature current can be cut off directly. When used in such an application, this structure composed of a slip ring or the like provides the electric motor 102 (power generation device) in synchronization with the power cutoff operation of the magnetic coupling 115 (power cutoff mechanism).
This constitutes an electric energy supply cutoff means for cutting off the supply of electric energy to the electric power supply. When such a structure of the electric energy supply cutoff means is adopted, if the electric motor 102 is a DC motor, the slip rings 116 and 117 are used.
And the sliding contacts 120a, 121a and the spring contacts 118, 1
The configuration of 19 may be one set. However, when the motor 102 is a multi-phase motor such as a three-phase AC motor, three sets of these configurations may be prepared so that an armature current flows through the armature winding of each phase of the motor. FIG. 10 is a conceptual diagram of a configuration in a case where, for example, an armature current of a three-phase AC motor is supplied using the above configuration. In these figures, 116
A to 116C are three-phase drive-side slip rings electrically insulated from each other, 117A to 117C are driven-side slip rings electrically connected to each other, and 118A to 118C and 119A. 119C is a spring contact, and 120ac-120aa and 121ac-121
aa is a sliding contact. With such a configuration, an armature current can be supplied to the armature winding of the motor through the sliding contacts 120ac to 120aa. When the magnetic coupling is out of step, the spring contacts 118A to 11A
8C and 119A to 119C are in a non-contact state, so that the supply of the armature current to the electric motor can be directly and immediately cut off.

When the output shaft and the rotating shaft of the electric motor are commonly used as in the second embodiment, the cut-off operation detecting means using the search coil as a sensor adopted in the first embodiment is used. Of course, it is good.

FIG. 11 shows a schematic configuration of an example of the third embodiment of the present invention. First Embodiment and Second Embodiment
Although the embodiment is an example of an electric actuator using a rotary electric motor as a power generation device, the present invention can also be applied to a linear electric actuator using a linear motor performing a translational motion as a power generation device. In FIG. 11, reference numeral 201 denotes a linear motor. This linear motor 2
01 is provided with an armature core 201a on the stator side, and the armature winding 2
01b is wound to form a fixed magnetic pole. 2
Reference numeral 02 denotes a movable body. The movable body 202 includes a movable body main body 203 and a pair of opposed wall portions 204 of the movable body main body 203.
A pair of guide pins 205 fixed to 204
And a movable element 206 having both ends slidably supported by the guide pins 205, 205. A plurality of permanent magnets 207 and a plurality of permanent magnets 208, which form a plurality of magnetic poles, respectively, are arranged on the opposing surfaces of the movable body 203 and the mover 206 at predetermined intervals in the moving direction. . A permanent magnet 201c that constitutes a field pole of the linear motor 201 is provided on the stator-side surface of the mover 206.
Are fixed at predetermined intervals in the moving direction.

In this example, the movable member 206 constitutes a driving member to which power (or torque) is directly transmitted from the linear motor 201, and the movable member 206 and the permanent magnet 20
.. Constitute a first magnetic coupling member 209. The movable body 203 is connected to a drive member by a magnetic coupling to form a driven member that transmits power (or torque) to a load. The movable body 203 and the permanent magnets 207 form a second magnetic field. A coupling member 210 is configured. And permanent magnet 2
07 and 208 constitute magnetic attraction force generating means for generating a magnetic attraction force. Also, the first and second magnetic coupling members 209 and 210 form a magnetic cup constituting a power cut-off mechanism (or torque cut-off mechanism) for blocking transmission of power (or torque) from the linear motor 201 to a load. A ring 211 is configured.

In this example, when the magnetic coupling 211 is in the connected state, the movable element 206 and the movable body 20
3 move synchronously, and when the magnetic coupling 211 is out of step, the mover 206 moves only by being guided by the guide pin 205, and power (torque) is not transmitted to the movable body 203.

In this example, it is needless to say that a cutoff operation detecting means, an electric energy supply stop means, and an electric energy supply cutoff means similar to those described above may be further provided.

According to each example of the above configuration, even when the motion mechanism section loaded on the electric actuator comes into contact with an object, for example, when a human body or the like is sandwiched between a moving part and a stationary part, abnormalities can be obtained. , And power from the electric actuator to the load is instantaneously shut off without relying on the detection of the power and software control of the electric actuator. Thus, an inherently safe electric actuator suitable for a fail-safe design of the system can be provided.

[0063]

According to the present invention, when a load (movement mechanism) driven by an electric actuator collides with an object, it is not necessary to detect the collision or control the software of the electric actuator. There is an advantage that the power transmission to the load can be interrupted only by the above.

If the mechanism for transmitting the power (or torque) and interrupting the power (or torque) is constituted by a magnetic coupling, the power (or torque) transmission can be instantaneously interrupted, and the occurrence of abnormality can be prevented. Can respond quickly.

Further, when the magnetic poles of the magnetic coupling are constituted by permanent magnets, the structure becomes simple and the electric actuator can be made compact.

Further, if an electric energy supply cutoff means for cutting off electric energy supplied to the power generation device in synchronization with the step-out of the magnetic coupling is provided, the power generation device is quickly stopped in synchronization with the detection of an abnormality. Can be done.

Further, a shut-off operation detecting means for generating a stop signal generated in synchronization with the step-out of the magnetic coupling is provided.
Advantageously, when the electric energy supplied to the power generation device of the electric actuator is stopped or cut off, the electric actuator can be stopped quickly, and the electric actuator can be prevented from operating again without removing the cause of the abnormality. There is.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view illustrating a structure of an electric actuator according to a first embodiment of the present invention.

FIG. 2 is a radial sectional view showing a configuration of a magnetic coupling used in the example of FIG.

FIG. 3 is an explanatory view used to explain an operation of a magnetic coupling unit used in the present invention.

FIG. 4A is a diagram showing a relationship between an angular displacement θ of a magnetic coupling and a torque Tc according to the present invention, and FIG. 4B is a diagram showing a relationship between a magnetic pole width dimension τ and a gap inner diameter D of the magnetic coupling. It is a figure, (C) is a figure which shows the time change of the force at the time of a collision, and (D) is a figure which shows the escape torque characteristic of an electric actuator.

FIGS. 5A and 5B are a plan view and a side view of a permanent magnet that can be used in the example of FIG. 1;

FIG. 6 is a configuration diagram of a search coil and a rotary transformer used in the example of FIG. 1;

FIG. 7 is a characteristic diagram showing a change in torque and a change in force generated on the load side obtained in a collision test performed on the example of FIG. 1;

FIG. 8 is a partial cross-sectional view illustrating a structure according to a second embodiment of the present invention.

FIG. 9 is a diagram showing a configuration of a brush and a slip ring used in the example of FIG. 7;

FIG. 10 is a diagram showing a configuration of a brush and a slip ring when a three-phase AC motor is used.

FIG. 11 is a diagram showing a structural concept of a third embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1,101 Electric actuator 2,102 Electric motor (power generation device) 3,103 Sensor part 4,104 Power transmission part 5 Casing 6,106 Output shaft 8,11,108,111 Permanent magnet support 10,12,110,112 Permanent magnet 13,113 First magnetic coupling member 14,114 Second magnetic coupling member 15,115 Magnetic coupling (power cutoff mechanism or torque cutoff mechanism) 18 Search coil 19 Rotary transformer 116,117 Slip ring 118 , 119 Spring contact 120, 121 Sliding contact structure 120a, 121a Sliding contact

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Manabu Matsushita 1-15-1-1, Kita-Otsuka, Toshima-ku, Tokyo Inside Yamayo Denki Co., Ltd. (72) Shinji Suzuki 1-1-55 Kita-Otsuka, Toshima-ku, Tokyo No. 1 Sanyo Denki Co., Ltd. (72) Inventor Shokichi Yasukawa 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Co., Ltd. (72) Inventor Naonori Nakamura 2-6-36 Daimyo, Chuo-ku, Fukuoka City, Fukuoka Prefecture No. BPP Inc.

Claims (15)

[Claims] A power generation device that converts electric energy into kinetic energy to generate power; a power transmission mechanism that transmits the power to a load; and a power transmission mechanism that is incorporated in the power transmission mechanism and transmits the power to the load. A power cut-off mechanism that cuts off the power supply, wherein the power cut-off mechanism detects the change in the load and detects the power to the load when a force received from the load becomes larger than a predetermined upper limit. An electric actuator, wherein the electric actuator is configured to cut off transmission of an electric current. 2. A power generation device that converts electric energy into kinetic energy to generate power, a power transmission mechanism that transmits the power to a load, and a power transmission mechanism that is incorporated in the power transmission mechanism and transmits the power to the load. A power cutoff mechanism for blocking the power from being transmitted, as one unit, wherein the power cutoff mechanism is connected to the drive side member by a magnetic coupling utilizing magnetic attraction and a drive side member to which the power is directly transmitted. A driven side member that transmits the power to the load, and a magnetic attractive force generating unit that is provided on at least one of the driven side member and the driven side member and generates the magnetic attractive force, When the force applied from the load to the driven member becomes greater than the coupling force of the magnetic coupling, the magnetic coupling is performed within a finite time determined to be safe. The electric actuator is configured to be out of step and cut off transmission of the power to the load. 3. An electric motor having a rotating shaft, a torque transmitting mechanism for transmitting a rotating torque of the rotating shaft to a load, and being incorporated in the torque transmitting mechanism to block transmission of the rotating torque to the load. 1 with torque cut-off mechanism
The torque cut-off mechanism is configured as a single unit, and the torque cut-off mechanism is connected to the drive-side rotating member by a magnetic coupling utilizing a magnetic attraction force, the driving-side rotating member being directly driven and rotating by the rotating torque, and being connected to the load. A driven-side rotating member that transmits the rotational torque; and a magnetic attractive-force generating unit that is provided on at least one of the driven-side rotary member and the driven-side rotating member and generates the magnetic attractive force. When the torque applied from the load to the driven-side rotating member becomes larger than the escape torque of the magnetic coupling, the magnetic coupling is out of synchronization and the transmission of the rotational torque to the load is interrupted. An electric actuator, comprising: 4. The magnetic attractive force generating means is provided on the drive side member and the driven side member such that a plurality of magnetic poles are formed on opposing surfaces of the drive side member and the driven side member, respectively. 4. The electric actuator according to claim 2, wherein the electric actuator is made of a permanent magnet. 5. The magnetic poles are arranged along the direction of movement of the drive-side member, and the size of each magnetic pole in the direction of movement is such that the time required for the magnetic coupling to reach a step-out state is safe. The electric actuator according to claim 4, wherein the electric actuator is set so as to be within a time required for securing the electric power. 6. A plurality of slits or grooves are formed on a pole face of the permanent magnet so as to suppress generation of an eddy current generated when the magnetic coupling is out of step. 3. The electric actuator according to claim 1. 7. The electric motor according to claim 1, further comprising an electric energy supply cutoff unit that cuts off supply of electric energy to the power generation device in synchronization with a power cutoff operation of the power cutoff mechanism. Actuator. 8. A shut-off operation detecting means for detecting a shut-off operation of power in the power cut-off mechanism and outputting a stop signal, and stopping supply of electric energy to the power generating device when the stop signal is input. The electric actuator according to claim 1, further comprising an electric energy supply stopping unit. 9. An interruption operation detecting means for detecting an operation of interrupting transmission of torque in the torque interruption mechanism and outputting a stop signal, and stopping supply of electric energy to the electric motor when the stop signal is input. The electric actuator according to claim 3, further comprising an electric energy supply stopping unit that performs the operation. 10. A driving-side slip ring, which has conductivity and is disposed concentrically with the driving-side rotating member, on the driving-side rotating member; A driven-side slip ring having conductivity disposed concentrically with the driving-side rotating member; and a magnetic coupling disposed between the driven-side slip ring and the driven-side slip ring. An electrical connection mechanism for electrically connecting the drive-side slip ring and the driven-side slip ring when in the coupled state, and interrupting the electrical connection between the two when the magnetic coupling is out of step; And a sliding contact structure having a pair of sliding contacts that are attached to the non-rotating portion and are always in contact with the driving side slip ring and the driven side slip ring. Electric actuator according to claim 9 are. 11. A motor having a rotating shaft, a torque transmitting mechanism for transmitting a rotating torque of the rotating shaft to a load, and a drive-side rotation incorporated in the torque transmitting mechanism and directly driven to rotate by the rotating torque. A driven-side rotating member connected to the driving-side rotating member by a magnetic coupling utilizing a magnetic attraction force to transmit the rotational torque to the load; the driven-side rotating member and the driven-side rotating member And a magnetic attraction force generating means for generating the magnetic attraction force provided on at least one of the driven member and the driven side rotating member, when the torque applied from the load is larger than the escape torque of the magnetic coupling, it is safe. The magnetic coupling is configured to be out of synchronism within a predetermined finite time so as to interrupt transmission of the rotational torque to the load, and A torque cut-off mechanism for blocking transmission of rolling torque to the load; a conductive drive-side slip ring disposed concentrically with the drive-side rotating member on the drive-side rotary member; A driven slip ring having conductivity disposed concentrically with the driven rotating member on a side rotating member; and being disposed between the driven slip ring and the driven slip ring. Electrically connecting the driving-side slip ring and the driven-side slip ring when the magnetic coupling is in a coupled state, and interrupting the electrical connection between the two when the magnetic coupling is out of synchronization. And an at least one pair of sliding contacts attached to the non-rotating portion and constantly in contact with the driving-side slip ring and the driven-side slip ring. Electric actuator; and a sliding contact structure, and supplying the armature current through at least a pair of sliding contacts to the armature winding of the motor that. 12. An electric motor having an n (n is a positive integer) -phase armature winding having a rotating shaft, a torque transmitting mechanism for transmitting a rotating torque of the rotating shaft to a load, and incorporated in the torque transmitting mechanism. A driving-side rotating member that is directly driven and rotated by the rotating torque, and a driven side that is connected to the driving-side rotating member by a magnetic coupling that utilizes magnetic attraction and transmits the rotating torque to the load. A rotating member, and a magnetic attraction force generating means provided on at least one of the driving side rotating member and the driven side rotating member to generate the magnetic attraction force, wherein the driven side rotating member receives the load from the load. When the applied torque becomes larger than the escape torque of the magnetic coupling, the magnetic coupling is out of synchronization within a finite time determined to be safe, and the rotation torque to the load is reduced. A torque cut-off mechanism configured to cut off the transmission of the torque and cut off the transmission of the rotational torque to the load; and a conductive member disposed concentrically with the drive-side rotary member on the drive-side rotary member. N drive-side slip rings having conductivity; n driven-side slip rings having conductivity disposed concentrically with the driven-side rotation member on the driven-side rotation member; And the drive side slip ring and the driven side, respectively disposed between the drive side slip ring and the n driven side slip rings and corresponding to the magnetic coupling in the coupled state. An electrical connection mechanism for electrically connecting the slip rings and disconnecting the electrical connection between the two when the magnetic coupling is out of synchronization; and A sliding contact structure having n sets of at least one pair of sliding contacts that are always in contact with the lip ring and the n driven-side slip rings, respectively, wherein the n-phase armature winding of the electric motor is provided. An electric actuator, wherein an armature current is supplied to each of the n sets of at least one pair of sliding contacts. 13. The slip ring on the drive side and the slip ring on the drive side when the magnetic coupling is in a coupled state, wherein the electrical connection mechanism is fixed to the slip ring on the drive side and the slip ring on the driven side, respectively. The at least one pair of spring contacts that are in contact with each other so as to electrically connect the driven side slip rings, and cut off the electrical connection between the two when the magnetic coupling is out of step. 13. The electric actuator according to 10, 11, or 12. 14. The interrupting operation detecting means is provided on one of the driving side member and the driven side member, and is generated by the magnetic force generating means provided on the other of the driving side member and the driven side member. The search coil according to claim 7, further comprising: a search coil configured to generate an induced voltage by a change in magnetic flux, wherein the electric energy supply stopping unit is configured to operate using the induced voltage induced in the search coil as the stop signal. Electric actuator. 15. An induced voltage induced in the search coil is such that a primary winding is provided on one of the driving side member and the driven side member provided with the search coil, and a secondary winding is non-rotating. The electric actuator according to claim 12, which is output via a rotary transformer provided in the unit.