JP3332397B2 - Output shaft sealed linear motion actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator (operating device) in which an output section moves forward and backward, and particularly, an environment, water, oil, dust, corrosive gas, and the like, which adversely affect a motor section. For protecting motors from fluids, for controlling nuclear fluids including radioactive materials, for high pressure,
Explosion-proof for handling in explosive or flammable fluids, such as for operations in vacuum vessels, or conversely, for applications such as semiconductor manufacturing clean rooms where chemicals and foods are not required to be released from the actuator side, etc. It is suitable as an actuator used for an actuator or the like, and, of course, can be used as a linear motion actuator for general mechanism operation.

[0002]

2. Description of the Related Art Conventionally, as a direct-acting actuator, there has been a pneumatic, hydraulic or hydraulic cylinder piston. Examples of the electric type include a linear solenoid, and a mechanism using a mechanism for converting a rotational motion into a linear motion, such as a screw and a nut or a pinion and a rack, for rotating the motor.

[0003]

In recent years, computer control has been advanced, automation and labor saving have been advanced, and maintenance free has been demanded from this, and there has been a trend to control everything by electrification.

As an actuator, a stepping motor (pulse motor) and a synchronous motor or an AC brushless DC motor (AC servomotor) obtained by converting the motor into an electric motor, which is a highly reliable motor without a brush, are used as electric actuators. It has become a trend to use.

[0005] Regarding the mechanism for driving the actuator, there is a great deal of applications for performing linear operation, not to mention an XY table using a ball screw and a ball nut.

However, if the output shaft of a rotating motor and the output shaft of a motor with a reduction gear are combined with a rotary motion converting mechanism in the relationship between a male screw and a nut, a direct-acting output can be obtained in a compact manner. Had a number of problems.

[0007] That is, as shown in the conventional example of FIGS.
Since the nut 4 must not rotate in order for the linear motion shaft to be related to the nut 4, the D-cut portion 5 or the spline coupling is provided on the outer periphery of the nut 4 and the rotation restricting member 6 is provided. Thus, the rotation of the nut 4 must be regulated and the rotation regulating member 6 must be slid linearly.

As another method, as shown in FIG.
A screw 1 in which the rotation output shaft 8 of the speed reducer 7 is D-cut on both sides to make it look like a flathead screwdriver, and
0, and the nut 11 is fixed.

In this case, when the output shaft 8 rotates, the screw 10 moves directly, but also rotates, so that it cannot be used for non-rotatable applications. There are problems such as the necessity of welding the steel ball 12 or the like to reduce friction between the operation target and the linear motion operation shaft.

In addition, the configuration shown in FIG. 9 has a problem in that the object to be operated can be pushed but cannot be pulled, and a rotatable coupling is required to serve as this.

Another problem is that even when the electric linear actuator is used as an operation actuator for a linear valve, it is difficult to seal a fluid entering through a rotational gap between a rotary output shaft and a bearing. Kosho 28-4080
As shown in JP-A-46-27428, a method of sealing around the rotor of a motor is disclosed in
Japanese Patent Publication No. 53-29244 discloses a method of further sealing the output shaft after the rotation-to-linear motion conversion, and a method of further sealing the output shaft after the rotation-to-linear motion conversion with a bellows. As shown in the official gazette,
There were problems such as a complicated mechanism such as a method of sealing the entire outer periphery of the motor from the outside and a high cost due to difficult sealing technology.

The present invention is intended to solve the above problems. That is, the present invention achieves a rotation-linear motion conversion function without providing a special rotation regulating member,
In addition, an output shaft-sealed linear motion actuator that completely seals the linear motion output shaft, does not allow fluid or dust to enter the motor side, and does not release oil, dust, etc. from the actuator side is also provided. It is intended to do so.

[0013]

To achieve the above object, according to the Invention The output shaft seal type linear actuator of the present invention, the rotary output shaft of the motor, either the male screw and the female screw 1
A rotary screw consisting One, the outer end thereof so as to cover the rotary screw
Elastic seal that is fixed to the motor flange side
A linear motion screw which is screwed to the rotation screw and linearly moves is fixed to the inner central portion of the elastic seal body.
In addition, the regulation of the translation screw about the axis is performed by the elastic seal body.
Controlled by strong rigidity in the direction of rotation around the axis,
The elastic seal body is internally provided with respect to the translation screw.
The rotary screw and the linear drive screw without disposing the sliding friction part
It is characterized in that it is configured to be disposed only .

[0014]

According to the present invention, when the rotation output of the motor is rotated, the rotary screw rotates, and the direct-acting screw screwed to this and fixed to the elastic seal body is restricted in rotation and is directly rotated. Just move. Also, since the outer end of the elastic seal body is fixed to the motor flange side, the linear motion output shaft is sealed, so that no fluid or dust enters the motor side.
No fluid or dust is released from the motor side.

[0015]

FIG. 1 is a partial sectional front view showing a first embodiment of the present invention.

In FIG. 1, 13 is a bellows as an elastic seal, 14 is its open end, 15 is its closed end, 16
Is a motor (motor with reduction gear), 17 is its lead wire, 1
8 is a male screw shaft which is a rotary screw, 19 is a nut which is a direct drive screw, 20 is a motor flange, 21 is a coupling screw which is a direct drive output shaft, 22 is a counter output shaft, 23 is a manually operated rod, and 24 is an air Reference numeral 25 denotes a front bearing.

That is, the motor 16 rotates the male screw shaft 18 forward and backward by controlling the power supply to the lead wire 17.

The male screw shaft 18 is screwed with a nut 19, and the other end of the nut 19 is air-tightly fixed to the bellows 13 by brazing or the like. The open end 14 of the bellows 13 is air-tightly fixed to the motor flange 20 by brazing or the like.

When the male screw shaft 18 rotates forward and backward, the nut 19 is rotated.
Performs a linear motion while expanding and contracting the bellows 13,
Since the bellows 13 has strong rigidity against rotation,
The nut 19 cannot rotate.

The tip of the nut 19 has a coupling screw 2
1 and is connected to an operation object (not shown) to perform linear motion control.

The rotation of the manual operation rod 23 provided on the non-output shaft 22 of the motor 16 causes the coupling screw 2 which is a direct-acting output shaft to be manually operated in a state where power is not supplied to the motor 16.
1 can operate.

Thus, a simple and small component,
A direct-acting output shaft seal can be achieved with only the three points of the male screw shaft 18, the nut 19, and the bellows 13. Therefore, the rotating shaft of the motor can be protected from moisture, corrosive gas and the like, and conversely, grease, oil and the like of the motor bearing do not leak outside.

FIG. 2 is a partially sectional front view showing a second embodiment of the present invention.

In the second embodiment, the nut 19 is a rotary screw, and the male screw shaft 18 is a direct-acting screw fixed to the inside center of the closed end 15 of the bellows 13 by brazing.

In the second embodiment, the same operations and effects as those in the first embodiment are obtained.

FIG. 3 is a partially sectional front view showing a third embodiment of the present invention.

In the third embodiment, the motor 16 is manufactured by using a male screw shaft 18 as a screw output shaft, and separately from this, a nut 19, a bellows 13, and a flange 26 with a bellows are manufactured. The motor flange 20 and the bellows-equipped flange 26 are sometimes caulked with reference to the outer diameter of the front bearing 25, and are integrated by welding, screwing, or the like.

In the third embodiment, the same operations and effects as those in the first embodiment are provided.

With such a structure, the nut 1
The mutual airtightness test of the bellows 13, the bellows 13 and the bellows with bellows 26 can be easily performed, and a reasonable production can be performed.

FIG. 4 is a partial sectional front view showing a fourth embodiment of the present invention.

In the fourth embodiment, when the upper and lower stoppers are provided, that is, when the male screw shaft 18 rotates and the nut 19 moves to the motor side, the steel ball 27 welded to the tip of the male screw shaft 18 is formed. It hits the nut 19 and serves as a top dead center stopper. If the nut 19 moves to the side opposite to the motor, the bellows 1
The lower dead center stopper 28 comes into contact with the cover-shaped lower limit stopper 28 covering the cover 3. The other parts are the same as in the first embodiment.

FIG. 5 is a partially sectional front view showing a fifth embodiment of the present invention. That is, this is an embodiment applied to a direct acting valve such as a globe valve and a needle valve.

The linear motion actuator is mounted on the valve flange 31 of the globe valve 30 by mounting screws 29.

Motor flange 20 and valve flange 31
An O-ring 32 is interposed between them to prevent the fluid 33 from leaking from the gap between the flanges.

A valve body 39 is fixed to the tip of the bellows 13, and the gap A between the valve and the valve seat 34 is controlled by rotation of a motor shaft to perform on / off control of fluid and proportional control.

As described above, if the control electric direct-acting valve is formed, the control valve can be formed very simply. Also, since the hermetic seal is performed by sealing and O-ring by bellows and metal brazing, highly reliable sealing can be performed.

The elastic seal used in the present invention is not limited to metal bellows such as stainless steel SUS304, 316L and phosphor bronze, but rubber or resin bellows may be used. As a functional condition of the elastic seal body, it is easy to expand and contract, but it is necessary to have a rigidity for restricting rotation.

From this, it is possible to use a diaphragm as the elastic seal body. The diaphragm consists of an elastomeric plate with great flexibility and extensibility. If it is a hard plastic or a metal with a corrosion-resistant elastomer lining, the diaphragm has a high resistance to corrosive liquids and is very advantageous.

FIG. 6 shows a sixth embodiment of the present invention in which a diaphragm is used as an elastic seal and applied to a direct acting control valve.

The male screw shaft 1 which is the rotation output shaft of the motor 16
8 and a nut 35 which is a direct-acting screw are screwed together, and the tip of the nut 35 is fixed to the diaphragm 36 by baking, bonding, welding, welding, or the like. The outer peripheral portion of the diaphragm 36 is sandwiched between the motor flange 20 and the second flange 37 to be kept airtight.

Fixed part 3 between nut 35 and diaphragm 36
Reference numeral 8 has a function of restricting the rotation of the nut 35.

Motor 16, male screw shaft 18, nut 35,
A linear motion actuator composed of a rotary / linear motion converting portion of the diaphragm 36 is used by being mounted on the valve flange 31 while crushing the O-ring 32 with the mounting screw 29.

In this configuration, when the male screw shaft 18 of the output shaft of the motor 16 rotates, the nut 35 moves up and down, and the diaphragm 36 expands and contracts as shown by the dotted line and the solid line, and the valve seat 34 and the bottom of the diaphragm 36 The gap between them can be controlled, and the on / off and proportional control of the fluid can be performed.

[0044]

As described above, according to the present invention,
Since the open end of the elastic seal body 13 is air-tightly fixed to the motor flange, an air-tight type linear motion actuator can be obtained in combination with a sealing material such as an O-ring using the plane of the motor flange 20 . In addition , the linear motion screw 19
Because There is fixed to the inner center portion of the elastic sealing member 13, it is restricted rotation of該直Do screw 19 by the elastic sealing member 13, rotary screw 18, linear screws 19, elastic Sea
It has only three simple and compact components
To achieve a direct-acting output shaft seal structure,
Inside Le body 13 eliminates sliding friction portion for restricting the rotation of the nut, such as a conventional, therefore, after that can convert rotating output of the rotary drive source efficiently linear output, the rotation and linear motion conversion mechanism Since the number of parts is reduced, cost reduction and size reduction can be achieved, and there is no unstable element, so that reliability is further improved.

An inexpensive, brushless, highly reliable stepping motor or the like is used as a drive source to prevent contamination of water, corrosive fluid, radioactive fluid, etc., hazardous fluid, gas generated from the motor, dust, etc. It is possible to provide a seal actuator that meets demands for a clean room, a chemical or food related product, an explosion-proof or an explosion-proof fluid that handles flammable fluids.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional front view showing a first embodiment of the present invention.

FIG. 2 is a partially sectional front view showing the second embodiment.

FIG. 3 is a partial cross-sectional front view showing a third embodiment.

FIG. 4 is a partial cross-sectional front view showing the fourth embodiment.

FIG. 5 is a partial cross-sectional front view showing a fifth embodiment.

FIG. 6 is a partial sectional front view showing the sixth embodiment.

FIG. 7 is a partial cross-sectional front view showing one example of a conventional relationship between a drive source rotation output shaft and a nut.

8 is a partial cross-sectional plan view of FIG.

FIG. 9 is a partial cross-sectional front view showing another example of a conventional relationship between a drive source rotation output shaft and a nut.

[Explanation of symbols]

 13 Bellows 14 Open end 15 Closed end 16 Motor 18 Male screw shaft 19 Nut 20 Motor flange

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-176283 (JP, A) JP-A-2-118552 (JP, U) JP-A-3-63062 (JP, U) JP-A 57- 139262 (JP, U)

Claims (1)

(57) [Claims] 1. A rotary screw comprising one of a male screw and a female screw on a rotary output shaft side of a motor ,
The outer end is fixed to the motor flange side to cover
And a possible elastic seal member are provided.
A linear motion screw that is screwed to the rotary screw and linearly moves is fixed to the side center portion, and the linear motion screw is regulated around the axis by strong rigidity in the rotational direction around the axis of the elastic seal body. Then, the elastic seal body is placed inside the
The rotation can be performed without providing a sliding friction portion for the dynamic screw.
An output shaft sealed linear motion actuator characterized in that only a screw and a linear motion screw are provided .