JPH0537373Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention is attached to a valve actuator, and when the rotating shaft reaches a set torque or higher, the overload detection mechanism is activated and the torque switch is opened. This invention relates to a torque switch mechanism capable of returning the torque switch with a small rotation angle of a limit switch operating shaft.

(Prior Art) When a valve is opened or closed, an overload condition occurs when a stone gets caught or the valve gets jammed into the valve seat. At this time, in order to stop the drive motor of the valve actuator, it is common practice to operate a torque switch using an overload detection mechanism to stop power supply to the drive motor.

In conventional valve actuator torque switches that use a micro switch, the micro switch is actuated by displacement of the worm shaft in the thrust direction, which is biased by a spring. Taking into consideration the long-term reliability of the micro switch and the risk of chattering occurring when the switch resets due to self-lock, which could damage the device or the micro switch and shorten its life, we adopted a cam switch with a snap-action mechanism. An intermediate lever that engages with the lever of the cam switch is supported by a shaft, and the rotation of a return cam attached to the shaft of the limit switch presses the intermediate lever to return the cam switch. Further, this return cam was provided with a differential mechanism in order to avoid interference due to simultaneous operation with the overload detection mechanism.

(Problem that the invention aims to solve) However, in this conventional cam-type torque switch, which uses a return cam to press the intermediate lever that engages with the lever, the return cam rotates and presses the intermediate lever, so the return Depending on the stop position of the cam, it is not possible to press the intermediate lever and return the torque switch until it has rotated approximately one rotation.

Furthermore, due to the operation of the differential mechanism, the torque switch may not be able to return until approximately 1.7 rotations, which causes the problem that the limit switch returns before the torque switch returns, resulting in an erroneous signal being output. It was hot. Another problem was that the sequence became complicated.

(Means for Solving the Problems) The present invention has been made to solve the problems of the conventional art. It is an object of the present invention to provide a practical torque switch mechanism that can immediately return the torque switch by rotation.

The gist of the present invention that achieves this purpose is as follows: An overload detection mechanism that is provided in the middle of the transmission mechanism of the valve actuator and rotates the torque lever when a load exceeding a set torque is applied; A torque switch with a snap action that rotates the lever and operates the switch, which stops the power supply to the valve actuator's drive motor, and a limit switch that operates in conjunction with the valve actuator's transmission mechanism. A gear is fixed to the limit switch actuating shaft, and a geared return cam that rotates in mesh with the gear is pivotally supported, and the gear is slid on one peripheral edge of the return cam and engaged with the lever of the torque switch. In addition, a stopper pin is provided to pivotally support the return lever that closes the torque switch by the rotation of the return cam, and engages with the left and right protrusions of the return cam to limit its rotation angle, and the gear of the return cam is connected to the limit switch operating shaft. A spring is formed only on a part of the opposing periphery of the gear fixed to the gear, and a spring is attached to bias the return cam in the direction of disengaging the return cam from the gear.Furthermore, when the torque switch lever is rotated in the opening direction, the lever is The lever, return lever, and return cam are arranged in a positional relationship in which the peripheral edge of the return lever is pressed to rotate the return lever, and one end of the rotated return lever slides on the return cam, moving the return cam toward the gear and meshing with the gear. The torque switch mechanism of the valve actuator is characterized by the following.

(Function) The present invention includes a limit switch operating shaft to which a gear is fixed, a return cam with a gear that rotates in mesh with the gear, and a return cam that slides on the return cam and engages with the torque switch lever. It is equipped with a return lever that rotates to close the torque switch.

When an overload occurs during valve opening/closing operation, the overload detection mechanism is activated, and the rotation of the torque lever of the overload detection mechanism moves the lever of the torque switch to operate the torque switch in the opening direction, and the drive motor of the actuator is activated. Stop power supply to.

At the same time, the lever of the torque switch presses the periphery of the return lever to rotate the return lever. When the return lever rotates, a portion of its periphery slides on the return cam, moving the return cam in the direction of the gear and meshing with the gear of the limit switch operating shaft.

Therefore, the gear of the return cam immediately meshes with the gear of the limit switch operating shaft.

When the valve is reversely operated to eliminate the overload condition or after the overload condition, the limit switch operating shaft that is linked to the transmission mechanism of the valve actuator rotates, and the return cam that meshes with the gear rotates. The return cam rotates the return lever, and the return lever closes the torque switch. After this operation, the return cam is slid by a spring through the elongated hole to disengage the gear, and the return lever is also returned to its original position by the quick action of the torque switch lever in preparation for the next operation.

The number of revolutions required from the start of rotation of the limit switch operating shaft until the torque switch operates can be appropriately selected depending on the gear ratio between the limit switch operating shaft and the return cam, etc.

(Example) Examples of the present invention will be described below based on the drawings.

In the figure, 1 is a limit switch operating shaft, 2 is a gear fixed to the upper part of the limit switch operating shaft 1, 3 is a return cam, and 4 is a gear formed on the return cam 3, which is pressed by a return lever 5 to engage gears 2 and 4. When the terminal end 6 of the gear 4 is in the immediate vicinity of the gear 2, the gear 2 is in the direction opposite to the return direction of the cam-type opening torque switch 7 (the gear 4
When the return cam 3 is rotated in the direction of engaging the end of the gear 4, the return cam 3 slides through the elongated hole 8 by the distance of the teeth of the gear 4, and the gears are disengaged and the return cam 3 does not rotate any further. Does not rotate.

Further, 9 is a cam-type closing torque switch, 10 is a spring that operates the torque switches 7 and 9 with a quick action, and 11 is a torque switch 7,
The lever 9 is formed into a Y-shape and engages with the return lever 5. 12 is the sliding part of the return cam 3;
3 is the inclined surface of the return lever 5, 14 is the lever 11
15 is the stopper pin, 16 is the gear 4
A spring 17 that urges the return cam 3 toward the disengaged side is a lock portion that prevents the operation of the other return cam 3.

Further, 19 is a torque lever of the overload detection mechanism 18, and 20 is an absorption section at the time of turnover.

In the figure, 21 indicates the return position of the return lever 5, and 22 indicates the return position of the lever 11. When the torque switch 7 returns, the gear 2 rotates clockwise and the return cam 3 presses the return lever 5 without escaping. do.

The return cam 3 comes into contact with the stopper pin 15 at the last rotated position, and the return cam 3 comes into contact with the stopper pin 15,
The sliding part 12 of the return cam 3 slides, and the return cam 3 slides through the elongated hole 8, thereby shifting the gear 2.
and gear 3 is disengaged. Accordingly, the return lever 5 also returns to its returned position 21 by the snap action of the lever 11 by the spring 10.

In this embodiment, the torque switch 7 can be reset by only 0.2 rotation of the gear 2, and since there is no width in the operating range, the torque switch can always be reset accurately.

(Effects of the invention) As described above, according to the invention, the torque switch is reset by sliding the return cam into the gear of the limit switch operating shaft and engaging the gear of the return cam, so that the limit switch operating shaft is It is possible to return the gears from the meshed position without rotating them, and it is possible to always perform the operation at a constant minimum number of revolutions (less than one revolution). Therefore, the reset of the torque switch and the reset of the limit switch are not reversed, and the sequence can be simplified without causing any erroneous signals.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing an embodiment of the present invention, Fig. 2 is a sectional view taken along line A-O-B in Fig. 1, Fig. 3 is an enlarged view of the main part of the embodiment, and Fig. 4 is an embodiment. FIG. 1...Limit switch operating shaft, 2...
Gear, 3...Return cam, 4...Gear, 5...Return lever, 7...Opening torque switch, 8...
Elongated hole, 9... Closing torque switch, 11... Lever, 12... Sliding part, 13... Slope part, 14...
Engaging portion, 16... Spring, 18... Overload detection mechanism, 19... Torque lever.

Claims (1)

[Claim for Utility Model Registration] An overload detection mechanism that is installed in the transmission mechanism of a valve actuator and rotates a torque lever when a load exceeding a set torque is applied, and a torque lever of the overload detection mechanism. A torque switch with a snap action that rotates the lever and activates the switch and stops power supply to the drive motor of the valve actuator, and a limit switch operating shaft that is linked to the transmission mechanism of the valve actuator. A gear is fixed to the limit switch actuating shaft, a geared return cam is pivotally supported and rotates in mesh with the gear, and the geared return cam slides on one circumferential edge of the return cam and engages with the lever of the torque switch. The return lever, which closes the torque switch with the rotation of the return cam, is pivotally supported, and a stopper pin is provided that engages with the left and right protrusions of the return cam to limit its rotation angle.Moreover, the gear of the return cam is fixed to the limit switch operating shaft. A spring is formed only on a part of the opposing periphery of the gear and is attached to bias the return cam in the direction of disengaging the return cam from the gear.Furthermore, when the lever of the torque switch is rotated in the opening direction, the lever moves around the periphery of the return lever. The lever, the return lever, and the return cam are arranged in a positional relationship such that the return lever is rotated by pressing , and one end of the return lever rotated at the same time slides on the return cam to move the return cam toward the gear and mesh with the gear. Features a torque switch mechanism for the valve actuator.