JPH0336942A - Motor drive for automatic control - Google Patents

Abstract

PURPOSE:To reduce the size of enclosing structure of motor case by arranging a ball screw mechanism between an annular motor and an output shaft. CONSTITUTION:A lock mechanism R is arranged on the center column 11 secured to the rotary table 7 of a motor M. The lock mechanism R locks the rotation through gearing of the circumferential teeth 11G of the center column 11 and teeth 12. Advance/retract of the gearing teeth 12 is controlled based on a signal fed from a displacement detector S. The center column 11 is coupled through a ball screw mechanism with an output shaft 19. Consequently, the ball screw mechanism A is positioned in the center column 11. Rotation of the output shaft 19 is locked by engaging the rotation lock metal 20 on the output shaft 19 with the guide rod 21 of housing 22, then the rotary power of the nut section 18 in the ball screw mechanism A is converted into advance/ retract motion of the output shaft 19. By such arrangement, the mechanism is simplified resulting in a compact and highly reliable annular motor.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electric drive machine for automatic control used as a valve actuator or the like.

[Conventional technology]

A typical electric drive machine is equipped with a speed reduction mechanism including a gear train or the like for converting rotational power of an electric motor into forward and backward movement of an output shaft. Gears, etc., have a structure that inherently has a locking function.When the power to the electric motor is cut off, a holding force acts on the output shaft, preventing the electric motor from being driven from the load side. ing.

On the other hand, in electric drives used for automatic control, the electric motor is controlled by a control mechanism, and a position limit switch is placed at the drive end to set the operating range of the output shaft. When the target position is reached, the position limit switch works and the control mechanism passes through the electric motor! It is supposed to be cut off at '.

Further, this type of electric drive machine operates much more frequently than a normal electric drive machine, and is often used in locations where load fluctuations are large. For example, in an electric drive machine installed as a valve actuator for flow rate adjustment in a power plant boiler, the valve body must be driven frequently, and the valve body is exposed to high-temperature, high-pressure steam.Moreover, the valve body must be Thermal expansion that comes into contact with air can cause a large load to be applied to the shaft.For this reason, in automatic control electric drives with conventional gear-type reduction mechanisms, first, the electric motor is of a high-speed multi-rotation type. The deceleration mechanism is equipped with a large number of deceleration-related parts to ensure high torque is obtained from the output shaft, and an accompanying torque limit that operates when an abnormal load is applied to the output shaft. A switch mechanism is installed to protect against motor burnout.

[Problem to be solved by the invention]

However, if the speed reduction mechanism has many components, it becomes mechanically complex, and the amount of lubrication and grease used increases accordingly.

For this reason, the conventional electric RA drive machine case for automatic control has been forced to have a large, sealed structure.

The present invention has been made with attention to these problems, and it is an object of the present invention to effectively solve these problems.

[Means to solve the problem]

In order to achieve this object, the present invention employs the following structure.

That is, the automatic control electric drive a! of the present invention! is a ring-shaped electric motor with a ring-shaped single trochanter that generates 1 kV, and is arranged inside this ring-shaped motor, and has a v7 otsuk function (converts the rotational power of the U motor into forward and backward movement of the output shaft). This ball screw mechanism is unique in that it is equipped with a displacement detection mechanism and metal fittings for detecting the displacement of the output shaft of this ball screw S structure.

[For production]

Since the ball screw i structure can obtain a relatively large reduction ratio with a simple configuration, it can be compactly installed between the 1g' motor and the output shaft instead of the conventional complicated gear reduction mechanism. The use of lubrication bends can also be minimized. Moreover, the electric motor and the output shaft are
If they are connected by a ball screw machine 476 that does not have a 70 torque function, the drive will be stopped when the output shaft reaches a predetermined position.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a longitudinal cross-sectional view of the automatic control electric drive 4 of this embodiment in a state where it is attached to a control square which is a driven body. FIG. 2 is an enlarged view of a portion of the electric motor M connected to the first line, and FIG. 3 is a sectional view taken along the top line I of FIG.

The electric drive machine of the present invention is characterized in that it uses an annular '1LvJ motor, and this electric motor M is made of metal as shown in, for example, Japanese Utility Model Application Publication No. 171465/1983. . As shown in Fig. 2 and Fig. 3, the motor M consists of an outer stator 1p and an inner stator 2, which are arranged as counter currents with a certain nitrogen gap, and a ring-shaped stator inserted into these gaps. It consists of a rotor 3. The outer stator] and the inner stator 2 are the motor housing metal outer cylinder 4.
and are fixed to the inner cylinder 5. ,Kata,l!
The JJ trochanter 3 is erected on a rotary table 7, and this rotary table 7 is rotatably supported by the inner cylinder 5 via a bearing 6. Each of the stators 1.2 i1a, 2a and
On both opposing sides of the rotor 3, comb-shaped salient pole elements are provided, as shown in FIG. -1 The trochanter 3 is made of a permanent magnet, and each pole of the stator 1.2 is 1a%.
22K is equipped with carp/L/1b and 2b, respectively. These coils 1b and 2b are connected to a control power source (not shown) so that three-phase alternating current is supplied to them.
By varying the frequency deposit in the range of n~OHz? ) By adjusting the four-wheel speed and fully varying the current amount [1liJ
The rolling driving force t-p can be adjusted. Furthermore, a rotor 8 whose entire outer circumference is machined into a comb-teeth shape is fixed to the outer periphery of one end of the rotating table 7, and a rotor 8 whose entire outer circumference is machined into a comb-teeth shape is fixed to the outer circumference of one end of the rotary table 7. Place the stator 9 and wait. A coil 93ti is attached to this stator 9. That is, when the rotary table 7 rotates, a pulse current signal corresponding to the rotation speed is obtained from the coil L'9a wound around the stator 9.

For the electric motor M configured as x5, a center column lit is fixed to the rotary table 7 thereof, and a locking mechanism Ri is housed at the upper end of the center column 11. The rotation of this locking mechanism R is locked by the meshing teeth 12 meshing with the circumferential teeth 110 at the upper end of the center column 11.

The meshing teeth 12 move back and forth by an electromagnet 13, and the electromagnet 13 is operated by a signal from a displacement detector (discussed later).

On the other hand, a screw shaft (output shaft) 19k is connected to the center column 11 via a ball screw mechanism.

The ball screw mechanism A is located inside the center column 11, and this point is also a feature of the present invention.
It is composed of a bolt part 19a carved at one end of the screw rod 19, and a large number of rolling bows *18a that connect the bolt part 19a and the nape part 18 in a screwable manner. A rotation stopping metal fitting 20 as shown in FIG.
By engaging with the screw rod 19, the rotation of the screw rod 19 is completely inhibited, and the rotation power of the nut portion 180 can be converted into forward and backward movement of the screw rod 19.

On the other hand, an arm 15 is fixed to the stopper 20, and a core rod 16 that is inserted into the differential transformer 17 and displaced is attached to the tip of the arm 20.

This displacement of the screw rod 19 is detected in terms of [gC]. That is, these constitute a displacement detection mechanism s2 of the screw rod.

A valve shaft 24 is connected to the other end of the screw rod 19 via a turnback/L/23, and a valve plug 25 having a suitable curved surface is integrally attached to the tip of the valve shaft 24. It is. The valve plug 25 is assembled with the valve seat 26 and the core metal aligned, and the area of the transparent area formed between the opening of the valve seat 26 and the opening of the valve seat 26 is changed depending on the forward and backward positions, and the valve body 2
The flow rate of the fluid flowing through the tube 7 can be adjusted. For this reason, the advance/retreat position it of the screw rod 19 is set to have a specific functional relationship with the flow rate of the fluid flowing inside the valve body 27. Further, the housing 22 and the valve body cover 28 are connected to the napht 2
It is fixed by 9.

On the other hand, the fourth circuit is a circuit D8i that controls the operation of this embodiment.
FIG. 31 is a controller which, when a target value is given, emits a DC [q@g or digital μ signal SI'lr according to the target value 4, 32 a comparison Il! ! In the circuit, a signal S from the controller 31 and a signal S from a displacement detector S provided to detect the position of the screw rod 19 are detected.
Compare 2 and gold, and if there is a difference, multiply by Igi+jS3 warehouse. The signal 4g-84 is a pulse signal proportional to the rotational speed of the electric motor M transmitted from the coil 9a. 34 is a motor drive circuit; Comparison with circuit 3501g No. S5 Yoro 3
A signal S6 corresponding to the difference between the two signals and the signal S3 is added. The output of the motor drive circuit 34 is input to the motor drive amplifier 36, and the output is a three-phase alternating current, and the output frequency changes from N to zero, and the drive voltage V changes accordingly.

When the signal S6 applied to the motor drive #J circuit 34 becomes zero, the output frequency t&N becomes zero. The motor drive (2) path 34 and the calculation circuit 35 are always communicated by a signal S7, and the three-phase AC output frequency aN and voltage V are determined from this signal S7 and the aforementioned signal S6.

At the same time, when the signal S6 becomes zero, the @ number S8 outputs a signal to the electromagnet drive 4-way 37, and the electromagnet 13t is operated to perform the 7-stroke operation.

According to the illustrated electric drive machine, there is no complicated mechanical part such as a gear train, and the use of lubricating oil or grease is only necessary because of the ball screw mechanism. Therefore, a large case with a conventional sealed structure is unnecessary, and a compact configuration can be realized. Furthermore, since the mechanism is simple, reliability is improved and maintenance is convenient. The fact that there is no need for a casing or a μ limit switch is also effective for compactness, and this fLI/Cx,
This eliminates the need for mechanical adjustment, making handling convenient.

Furthermore, even if a load fluctuation occurs due to a change in the state of the valve plug 25, the control pulp V can be reliably maintained in a closed state while automatically making corrections to follow the change, thereby improving performance. Same as above. As a result of the above, this product can be effectively used for purposes that require stable operation over a long period of time under severe conditions, for example, as a pump actuator at a power plant.

In the above embodiment, a Sanwa type servo motor is used as the motor 7, but other electrically controlled motors such as a pass motor can also be used. Furthermore, the displacement detection mechanism is not limited to the differential Torunne system, but may be a system that detects displacement sound by converting pulses using magnetic force, such as the product name "Magnescale". The locking mechanism is also not limited to the illustrated example. Also, this locking mechanism is not always necessary. This is because the motor performs the brake function TW. Furthermore, it goes without saying that the driven body is not limited to valves, and various types of f! can be effectively used as a drive unit for a close positioning mechanism.

〔Effect of the invention〕

Since the present invention has the above configuration, the following effects can be obtained. In other words, it is used for annular electric motors,
In addition, since a ball screw machine +g k is used to open the output shaft and is arranged inside thereof, the mechanism is simplified, and a compact external shape and high reliability can be obtained. Moreover, since the power consumption of grease and the like is reduced, a large case with a conventional sealing mechanism is not required. Furthermore, since there are no parts that require mechanical adjustment such as a top limit switch, handling is also extremely simple.

[Brief explanation of drawings]

Fig. 1 is a simplified side sectional view showing a metal control valve according to an embodiment of the present invention applied, Fig. 2 is a partially enlarged view of Fig. 1, and Fig. 3 is a cross-sectional view taken along line 2□□□. , FIG. 4 is a block diagram showing the control circuitry. A...Ball screw mechanism M...Annular electric motor S...Displacement detection mechanism SI)...Control four-way 3.
...Rotor 11...Center column 13...Electromagnet 17...Differential transformer 19...Output iII+
(Screw rod) 37... Electromagnet assembly @ Maji

Claims (1)

[Claims] An annular electric motor with a ring-shaped rotor, and a ball screw mechanism that is disposed inside this electric motor and does not have a self-locking function that converts the rotational force of this electric motor into forward and backward movement of an output shaft. An electric drive machine for automatic control, comprising: and a displacement detection mechanism that detects displacement of the output shaft of the ball screw mechanism.