JPH1182277A - Electrically-driven servomotor for driving guide vane of waterwheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To add a dash-pot function to an ordinary electrically-driven servomotor without providing a dash-pot independently or using a special electrically- driven servomotor. SOLUTION: A screw shaft 3 is rotated by the rotational force of a motor 11 through an oil-contained deceleration mechanism 1 in a case 2, its rotational motion is converted into a linear motion by a nut 4 integrated with an inner cylinder 6 which can slide inside an outer cylinder 5, an arm 6a joined to the inner cylinder 6 is joined to the guide vane of a waterwheel serving as an outside mechanism. Both the ends of the outer cylinder 5 and the case 2 are connected together by piping 7, 8, and a variable throttle valve 9 is formed at the piping 8. It is thus possible to brake rapid movement of the waterwheel guide vane due to power loss of the motor 11 with the dash-pot function by the variable throttle valve 9 and an oil-hydraulic circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric servo motor having a dashpot function for driving guide vanes of a water turbine.

[0002]

2. Description of the Related Art In recent years, the use of electric servomotors for driving guide vanes of Francis turbines and Kaplan turbines has been increasing. However, when the power of the electric servomotor is stopped and the driving force is lost during operation of the water turbine, the guide vane is rapidly closed by the closing force of the guide vane due to the water flow,
The water pressure in the penstock suddenly rises, and in the worst case, the penstock may burst.

For this reason, in order to prevent the guide vanes from closing suddenly when the electric servomotor loses the driving force, a dashpot for suppressing the closing speed is provided separately from the drive mechanism for the guide vanes. A special electric servomotor with a dashpot consisting of a cylinder and a piston was used in the mechanism of the servomotor.

[0004]

As in the above example, a dashpot independent of the electric servomotor is provided separately from the electric servomotor for preventing the guide vanes of the water turbine from closing suddenly, or a special electric servomotor incorporating the dashpot is provided. In this case, there is a disadvantage that the number of components increases and the configuration becomes complicated by the addition of the dashpot.

An object of the present invention is to simplify the configuration by adding a dashpot function to a normal servomotor without separately providing a dashpot or incorporating a dashpot in an electric servomotor.

[0006]

SUMMARY OF THE INVENTION The present invention comprises an electric motor, a reduction mechanism for reducing the rotation of the electric motor, and a conversion mechanism for converting the reduced rotational movement into a linear movement. The conversion mechanism comprises an outer cylinder and an outer cylinder. An internal cylinder guided by the cylinder to perform linear motion and transmit this linear motion to the outside.The front and rear of the internal cylinder are interlocked via a variable throttle valve and oil-sealed, and the conversion mechanism is a ball screw and ball This is a structure in which a rotary motion is converted into a linear motion by a nut or a roller screw and a roller nut.

[0007]

FIG. 1 shows the configuration of an embodiment of the present invention. The electric servomotor shown here comprises an electric motor 11,
A reduction mechanism 1 containing oil 21 contained in a case 2;
1, an outer cylinder 5, an inner cylinder 6 slidably housed inside the outer cylinder 5 and connected to an arm 6 a, a screw shaft 3, and a nut integrally connected to the inner cylinder 6 by rotating the screw shaft 3. The rotary motion of the screw shaft constituted by 4 is changed to a linear motion, and the transmission conversion mechanism is transmitted to the inner cylinder 6 and the outer cylinder 5 bisected by the inner cylinder 6.
And the pipes 7 and 8 provided with a variable throttle valve 9 and a check valve 12 on one side. Here, as the screw shaft 3 and the nut 4, a ball screw and a ball nut having extremely low frictional resistance, or a roller screw and a roller nut are used. In the case of the embodiment shown in FIG. 1, the operation direction in which the inner cylinder 6 moves toward the speed reduction mechanism is the guide vane closing direction.

According to this configuration, the rotation of the electric motor 11 which receives a signal to maintain the guide vane of the water turbine of the external mechanism from the home position to the new position is reduced by the reduction mechanism 1 to rotate the screw shaft 3, and this rotation is performed. Is converted into linear motion by the nut 4 and the inner cylinder 6 to move the arm 6a connected to the external mechanism, that is, the guide vane of the water wheel. During this time, when the inner cylinder 6 operates in the guide vane closing direction, the volume of the two spaces divided by the inner cylinder 6 in the outer cylinder 5 changes relatively due to the movement of the inner cylinder 6, and the pressure difference between the oil 21 inside and Although the inner cylinder 6 is braked by the dashpot function by the fluid resistance of the variable throttle valve 9, the constant of the variable throttle valve is selected so that the influence of this braking does not occur at the normal operation speed of the external mechanism. . Then, the inner cylinder 6
And the arm 6a and the guide vane of the water wheel associated therewith. When the inner cylinder 6 operates in the kite vane opening direction, the oil inside flows through the piping on the check valve 12 side having a small fluid resistance, so that the fluid resistance by the variable throttle valve 9 does not act on the opening operation of the electric servomotor.

In this state, if the power of the motor 11 is stopped and the driving force is lost, the torque of the electric motor 11 which has been maintaining the closing force of the guide vane of the water turbine due to the water flow is lost, and the guide vane of the water turbine is lost. Is applied to the inner cylinder 6 to move it in the guide vane closing direction. At this time, the moving speed of the inner cylinder 6 is suppressed to approximately the normal operation speed by the function of the dashpot, so that the guide vane is slowly closed. Therefore, the guide vane of the water turbine is prevented from moving abruptly, and the water pressure in the penstock can be prevented from rising rapidly.

FIG. 2 shows another embodiment slightly different from FIG. The difference is that the variable throttle valve 9 and the check valve 12 of the pipe 8 of FIG.
The operation direction in which is projected is the guide vane closing direction. The same components as those in FIG. 1 are denoted by the same symbols, and the description of the overlapping symbols is omitted. According to this configuration, the function becomes the same as that of FIG. 1, so that the guide vane of the water turbine can be prevented from moving abruptly, and the water pressure in the penstock can be prevented from rising rapidly.

[0011]

According to the present invention, since the dashpot function is integrally provided outside the electric servomotor, the construction can be simplified and the construction can be simplified as compared with the dashpot alone installation. A dashpot function can be added to the electric servomotor, and the equipment can be simplified and standardized without using a special electric servomotor with a dashpot function.

Further, by using a ball screw and a ball nut or a roller screw and a roller nut having extremely low frictional resistance on the screw shaft and the nut, it is possible to efficiently and reduce the trouble due to wear.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a configuration diagram of another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reduction mechanism 2 Case 3 Screw shaft 4 Nut 5 Outer cylinder 6 Inner cylinder 7 Piping 9 Variable throttle valve 11 Motor 12 Check valve 21 Oil

Claims (2)

[Claims] An electric motor, a deceleration mechanism for decelerating the rotation of the electric motor, and a conversion mechanism for converting the decelerated rotational motion into a linear motion. The conversion mechanism is guided by the outer cylinder to perform the linear motion. An electric servomotor for driving a guide vane of a water turbine, comprising: an inner cylinder for transmitting the linear motion to the outside; and a front and rear of the inner cylinder communicating with each other via a variable throttle valve and being oil-sealed. 2. The electric servomotor for driving a guide vane of a water turbine according to claim 1, wherein the conversion mechanism converts the rotary motion into a linear motion by a ball screw and a ball nut or a roller screw and a roller nut. .