JPS6139158Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of an actuator for a valve.

In actuators that operate valves, etc. by decelerating the output rotation of a rotary power source such as an electric motor or air motor, the degree of opening and closing of the valve can be determined from the axial position or rotational angle position of the valve shaft driven by the output shaft. In addition to the detection mechanism that detects
In order to avoid equipment damage due to overload, a detection mechanism is generally provided to detect output torque (load torque).

For example, an actuator for a gate valve normally rotates a nut (drive sleeve) whose hollow output shaft engages with the valve opening/closing screw shaft of the valve at a certain position, thereby rotating the screw shaft, that is, the valve shaft. For example, an actuator for a butterfly valve has a valve shaft of a valve in its output drive section by moving it in the axial direction without rotating it in the inner cavity of the hollow output shaft. A drive sleeve having a square hole that fits into the square end of the valve is connected to the drive sleeve, and by rotating the sleeve in the same manner as described above, the valve shaft is rotated and the valve is opened and closed. The hollow output shaft or the output drive section is constructed by interlocking the worm wheel to which it is integrally fixed with the worm fixed to the intermediate drive shaft which is rotated at a reduced speed from the driving shaft via a speed reduction mechanism. Rotation drive is performed.

To detect the output torque of this type of actuator, when the worm wheel is driven to rotate, the axial thrust Fa generated in the worm is determined by the output torque To.
Therefore, as shown in FIG. 1, a spring 4 is interposed with respect to the axial location of the worm 2, that is, the intermediate drive shaft 1, and the worm 2 is proportional to the deflection δ of the spring 4 due to the thrust force. This is done by detecting the amount of movement in the axial direction. If the spring constant is k, then To...Fa=
This is based on the fact that the relationship kδ holds true. The torque limit switch mechanism (torque limiter) is configured to take out the amount of movement of the worm in the axial direction as a detection signal, actuate a micro switch based on the signal, and cut off power to a prime mover, such as an electric motor. It is common that

FIGS. 1 and 2 take out the above-mentioned detection signal, and thereby a microswitch (not shown) is activated.
A conventional torque limit switch mechanism is shown. In the one shown in FIG. 1, a plurality of plate springs 4 are attached in contact with support ball bearings 3, 3' at both ends of a worm 2 that is integrated with the intermediate drive shaft 1, and the axial position of the intermediate drive shaft 1 is It is held within a certain range via a disc spring 4, and a rack 5 is carved on the outer periphery of the left extended shaft of the intermediate drive shaft 1 perpendicularly to the shaft, and a pinion 6 is engaged with the rack 5. . For example, worm 2, which has a right-handed twist,
Assuming that the worm wheel 5 rotates in the clockwise direction shown by the arrow and drives the worm wheel 5 that meshes with it in the clockwise direction shown by the arrow, a leftward axial thrust is generated in the worm 2, which causes the left disc spring 4 to deflect. Celebrated,
By this amount of deflection δ, the intermediate drive shaft 1 is connected to the ball bearing 3,
3' and move to the left. As a result, the rack part 5 rotates the pinion 6 that meshes with it clockwise in accordance with the amount of movement δ, and the actuating piece (not shown) connected to the rotating shaft 6' operates the micro switch. has been done.

The torque limit switch mechanism shown in FIG. 2 differs from the one in FIG.
As shown in Figures 1 and 2-2, a crank pin is implanted in a crank arm 12 fixed to the end of a rotatably supported rod 11, and a small ball bearing 13 is attached to it. A freely movable outer ring is adapted to engage with a neck provided on the left end extended shaft portion of the intermediate drive shaft 1, and a push bolt 15 is adjusted to the tip of a swinging arm 14 fixed to the right end of the rod 11. It can be installed freely. Therefore, the axial movement amount δ of the intermediate drive shaft 1
is converted into an angular displacement of the swing arm 14 via the crank 12 and the rod 11, and a micro switch (not shown) installed opposite the push bolt 15
The operation is performed by pushing the push bolt 15.

As described above, in the conventional actuator torque limit switch mechanism, the intermediate drive shaft 1 must be extended in order to process the rack or neck portion that transmits the output torque detection signal, that is, the amount of axial movement of the intermediate drive shaft 1. As a result, the main body casing of the actuator becomes larger, and the mechanism is difficult to assemble.

This invention aims to provide an actuator for a valve that eliminates the above-mentioned drawbacks.
A worm wheel having a drive unit connected to a valve shaft for opening and closing a valve and a drive sleeve for operating the worm wheel, and an intermediate drive shaft having a worm that meshes with the worm wheel driven from a prime mover via a reduction mechanism. an actuator comprising: a ball bearing of the intermediate drive shaft; and a ball bearing of the intermediate drive shaft. In order to detect the amount of axial movement of the worm through the outer ring, a rod having a crescent-shaped protrusion at its end is rotatably supported in a direction perpendicular to the intermediate drive shaft. A spring is installed to apply rotational torque in a certain direction so that the corner of the crescent-shaped protrusion is always in contact with the shoulder of the outer ring of the ball bearing, and a cam is further pivotally attached to the rod, and the cam is This invention relates to a valve actuator characterized in that it is provided with a micro switch operated by.

Hereinafter, embodiments of this invention will be described in detail with reference to the drawings.

Fig. 3 is a plan view of a device for a valve according to this invention, particularly a butterfly valve, with the cover removed, Fig. 4 is a side sectional view of the - section taken in the direction of the arrow, and Fig. 5 is a - cross section of the device taken in the direction of the arrow. It is a cross-sectional view seen in the direction. In the figure, 1 is an intermediate drive shaft, 2 is a worm, 3 and 3' are ball bearings installed at both ends, 4 is a disc spring, 7 is a worm wheel, in this case a sector worm wheel, and the intermediate drive shaft 1 is rotated while being decelerated through a worm 21 fixed to the output shaft of the electric motor 20 and a small worm wheel 22 that meshes with the worm 21, which meshes with the intermediate drive shaft 1 and the worm 2.
A drive sleeve 23 having a square hole that fits into the square end of the valve shaft of the butterfly valve is attached to the sector worm wheel 7, which is rotatably driven by the sector worm wheel 7, through a spring pin and a bolt. , 24 is a mount base for fixing the valve yoke of the butterfly valve, and is attached to the main body casing 25 with bolts.
26 is a manual knob for manual/automatic switching operation, and when it is pushed in to the left as shown in the figure, the worm 21 and small worm wheel 22 are held in an engaged state, and when pulled out to the right, these are kept in engagement. The mesh is released, the power transmission path from the electric motor 20 is cut off, and the intermediate drive shaft 1 can be manually rotated by turning the manual knob 26. 27 is a stopper,
It is attached to the main body casing 25 so as to be adjustable, and when either of the left and right end surfaces of the sector worm wheel 7 comes into contact with the end surface of the stopper 27, the micro switches 28, 28' of the torque limit switch mechanism are activated. Either one of them is activated to stop the electric motor 20.
Next, this torque limit switch mechanism will be explained based on the perspective view of FIG. 6, which shows the torque limit switch mechanism. 29 is a rod (torque detection shaft), and the vicinity of its lower end is not shown;
The upper end portions of the bearing portions fitted into the main body casing 25 are rotatably supported in bearing holes of the support plate 30, respectively. A crescent-shaped protrusion 31 is formed at the end of the rod 29, and a spiral spring 32 is mounted approximately in the middle. Since the spiral spring 32 applies torque to the rod 29 in the direction of the arrow shown in the figure, the corner of the crescent-shaped protrusion 31 is always in contact with the outer ring shoulder of the ball bearing 3'. . Cams 33 and 33' are attached to the rod 29 so as to be adjustable, for example, by push screws, close to the top and bottom, and serve to operate the micro switches 28 and 28', respectively. Reference numerals 34 and 34' are micro switches that operate in the fully closed and fully open positions of the valves, respectively, and the electric motor 20
It is a micro switch that cuts off the power to 3.
Reference numerals 5 and 35' denote actuating plate cams for operating the micro switches 34 and 34', respectively, which have holes through which the rods 36 pass, and are fixed to the upper end of the sector worm wheel 7, respectively. Rod 3
6 is inserted into a hole drilled at the center of rotation of the worm wheel 7 and bonded thereto, and a valve opening scale plate 37 is fixed to the upper end surface of the worm wheel 7. 38 is a fixed pointer, and the opening degree of the valve is displayed through a transparent viewing window 39 attached to the cover via a sealing material.

Next, the operation of this device will be explained.

As mentioned above, it is assumed that a butterfly valve is installed in this device. In both figures 3 and 5, the manual knob 26 is pushed to the left, the worm 21 and the small worm wheel 22 are engaged, and the electric motor 20
This shows a state in which automatic operation is possible. Let us now discuss the case of opening a valve that is in the fully closed position as shown in FIG. electric motor 20
and drive the intermediate drive shaft 1 through the worm 21 and the small worm wheel 22 that meshes with the worm 21.
When the worm 2 is rotated in the counterclockwise direction shown by the arrow in the figure, assuming that the worm 2 is twisted to the right, the sector worm wheel 7 that meshes with it is rotated in the counterclockwise direction shown by the arrow, and is attached to the drive part. The valve stem is also rotated counterclockwise via the drive sleeve 23, and the valve is gradually opened. The opening state is displayed through the viewing window 39 by the scale of the opening scale plate 37 that the fixed pointer 38 points to. When the load torque increases due to the fluid passing through the valve, the corresponding output torque will be transmitted from the worm 2 to the sector worm 7, so as mentioned above, a rightward thrust proportional to the output torque will be applied to the intermediate drive shaft. Occurs on 1. The thrust acts on the disc spring 4 through the ball bearing 3 and causes it to deflect, but when the deflection (compressive strain) reaches a certain level, the disc spring 4
The elastic force generated in the above-mentioned thrust force is balanced. Therefore, during this time, the intermediate drive shaft 1 is moved to the ball bearings 3, 3'.
At the same time, the outer ring slides against the main body casing 25 and is moved to the right by the amount of deflection. As a result, as shown in FIGS. 6 and 7, the rod 29 is pushed by the shoulder of the ball bearing 3' moving rightward on the corner of the crescent-shaped protrusion 31, so that the rod 29 is pushed from above by an angle α. It can be rotated counterclockwise.

In this device, the output torque increases as described above as the load torque increases, but if the load torque abnormally increases for some reason and the output torque reaches a predetermined maximum value, the intermediate The cam 33 attached to the rod 29 is rotated counterclockwise by a rotation angle corresponding to the amount of movement of the drive shaft 1. In this case, since the mounting angle position of the cam 33 with respect to the rod 29 is adjusted in advance so that the cam 33 operates the micro switch 28, the micro switch 28 is operated by the cam 33, and the electric motor 20 is The power is immediately cut off to prevent equipment damage due to excessive load.

When closing the valve from the fully open position, the rotation directions of the worm 2 and the sector worm wheel 7 are opposite to those described above, and the intermediate drive shaft 1
moves to the left, but even in this case, the corner of the crescent protrusion 31 of the rod 29 maintains contact with the shoulder of the outer ring of the ball bearing 3' by the torque applied from the spiral spring 32. Therefore, the rod 29 is rotated clockwise following the leftward movement of the outer ring, and when an overload similar to the above occurs, the cam 33' is rotated in the same manner as the cam 33.
The microswitch 28' is actuated and the electric motor 20 is stopped.

Further, since the valve opening indicating mechanism in this device is designed to directly indicate the rotational position of the valve shaft of the butterfly valve as described above, there is no error associated with the transmission mechanism. Although this opening degree indicating mechanism cannot be incorporated into an actuator for a gate valve, which is attached to the worm wheel 7 so that the hollow output shaft rotates a drive sleeve that is threadedly engaged with the screw shaft for opening and closing the valve, the torque limit The switch mechanism can be directly incorporated into a valve actuator other than the butterfly valve described above.

As is clear from the above description, in the valve actuator according to this invention, compared to conventional devices, the detected amount of output torque is extracted via the ball bearing supporting the intermediate drive shaft having a worm. Since the torque limit switch mechanism uses a simple transmission mechanism to convert angular displacement and a cam to operate a micro switch, it is necessary to extend it to extract the detected amount from the intermediate drive shaft. Therefore, it is possible to provide a device in which the actuator main body can be made compact and the transmission mechanism can be easily incorporated.

[Brief explanation of the drawing]

1, 2-1, and 2-2 are explanatory diagrams showing a mechanism for extracting the detected amount of output torque in a conventional device, and FIG. 3 shows an embodiment of the device according to this invention with the cover removed. 4th floor plan
The figure is a side sectional view of the - section viewed in the direction of the arrow.
Fig. 5 is a cross-sectional view of the - section viewed in the direction of the arrow, Fig. 6 is a perspective view showing the torque limit switch mechanism, and Fig. 7 is an explanatory diagram of its operation. 1... Intermediate drive shaft, 2... Worm, 3, 3'
... Ball bearing, 4 ... Belleville spring, 7 ... Worm wheel (sector worm wheel), 23 ... Drive sleeve, 28, 28' ... Micro switch, 29 ... Rod (torque detection shaft), 31 ...
...Crescent-shaped protrusion, 32...Spiral spring, 33,
33'...Cam.

Claims (1)

[Scope of utility model registration request] A worm wheel having a drive unit connected to a valve shaft for opening and closing a valve and a drive sleeve for operating the worm wheel, and an intermediate drive shaft having a worm that meshes with the worm wheel driven from a prime mover via a reduction mechanism. an actuator comprising: a ball bearing of the intermediate drive shaft; and a ball bearing of the intermediate drive shaft. In order to detect the amount of axial movement of the worm through the outer ring, a rod having a crescent-shaped protrusion at its end is rotatably supported in a direction perpendicular to the intermediate drive shaft, and a constant A spring is attached to apply a rotational torque in the direction, and the corner of the crescent-shaped protrusion is always in contact with the shoulder of the outer ring of the ball bearing.A cam is further rotatably mounted on the rod, and A valve actuator characterized by being equipped with an actuated micro switch.