JP2864680B2 - Shock absorber for fully closed guide vane in electric servomotor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock absorber for fully closing a guide vane in an electric servomotor for operating a guide vane of a hydroelectric power plant.

B. Summary of the Invention The present invention relates to a shock absorbing device when the guide vane is fully closed. The impact on the electric servomotor can be reduced when the guide vanes are fully closed by colliding with the body.

C. Prior Art Guide vanes used in Francis turbines control the amount of water flowing into the turbine, and the guide vanes are configured to be operated by an electric servomotor. The electric servomotor is operated by the control circuit shown in FIG. Here, FIG. 4 will be described.

In FIG. 4, reference numeral 1 denotes a Francis turbine, 2 denotes a gate link connected to a guide vane (not shown), and 3 denotes an arm having one end connected to the gate link 2 and the other end connected to the electric servomotor body 4.

A portion surrounded by a two-dot chain line is a control circuit 5, and the control circuit 5 is configured as follows.

Reference numeral 6 denotes a vector control device, which drives the drive motor 4a of the electric servomotor body 4 by the output of the vector control device 6. Reference numeral 7 denotes a changeover switch in which the vector driving device 6 is inserted into an electric path with the drive motor 4a.
When the control circuit 5 is out of order, the AC power is supplied directly to the drive motor 4a via the transformer 8 to forcibly drive the electric servomotor to completely close the guide vanes. Reference numeral 9 denotes a governor control device, which sends commands for opening and closing the guide vanes. Ten
Is an AC power supply abnormality detector, and 11 is a DC power supply abnormality detector.

When the electric servomotor main body 4 is controlled by the control circuit 5 configured as described above, there is the following three means for safely stopping the water turbine when an abnormality occurs in the power supply system. First, the first means supplies a DC power source for backup to the electric servomotor main body 4. The second means supplies AC power to the electric servomotor main body 4 via the transformer 8 when the control circuit 5 fails. The third means is to provide the water turbine guide vanes with a self-closing characteristic.

D. Problems to be Solved by the Invention As described above, there is the first to third means for closing the electric servomotor body 4 when an abnormality occurs in the power supply system. In the first means, since the control circuit 5 operates normally, the slow closing mode is added before the electric servo motor main body 4 is fully closed, so that the collision at the time of full closing can be reduced. This operating characteristic is shown by the solid line in FIG. FIG. 5 is a characteristic diagram of the electric servomotor closing mode. In FIG. 5, the solid line shows the characteristics of the first means, and the broken lines show the characteristics of the second and third means.

Since the second and third means are for the case where the control circuit 5 is out of order or the power supply is lost, the gradual closing mode at the time of fully closing cannot be performed.
For this reason, the guide vane operating rod collides with the internal stopper of the electric servomotor main body 4 in the state of the closing speed, and vibrates or rebounds as shown by a broken line in FIG.
The impact force at the time of the collision may damage the electric servomotor body.

The present invention has been made in view of the above circumstances, and does not affect the operation of the electric servomotor during normal operation.When control is abnormal, the closing speed of the electric servomotor is reduced to reduce impact. It is an object of the present invention to provide a shock absorbing device when the guide vanes are fully closed in an electric servomotor that is relaxed.

E. Means for Solving the Problems The present invention connects a rod projecting from an electric servomotor body and a guide vane operating portion of a water turbine with a guide vane operating arm, and connects a guide vane of the water turbine with an electric servomotor. A shock absorber including a rod projecting from the electric servomotor body, and a buffer oil mounted on the same axis as the rod and fitted with the rod movably in the axial direction. And a stopper provided at the tip of the rod and colliding with the collision buffer when the guide vanes are fully closed.

F. Action When the guide vane of the water turbine is fully closed when the control circuit of the electric servomotor body fails, the stopper at the rod end protruding from the electric servomotor body collides with the collision buffer. Then, the buffer absorbs the impact force due to the collision by the action of the oil enclosed therein. This prevents the rod from colliding with the electric servomotor body.

G. Embodiment In the following, an embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 21 denotes a case of the electric servomotor main body 4, and a gear device 22 is housed in the case 21. The gear device 22 is driven by a drive motor 23. Reference numeral 24 denotes a ball screw. An end of the ball screw 24 is fixed to the gear device 22, and a nut 25 is provided on the screw portion. One end of a rod 26 is fixed to the nut 25, and the other end is connected to the guide vane operation arm 3 via a stopper 27.
With this configuration, when the ball screw 24 is rotated, the nut 25 moves linearly, and this movement is transmitted to the rod 26.

A dash pot that serves as a shock absorber on the outer periphery of the rod 26
38 are provided. The dash pot 38 includes a piston 29 and a case 31. Reference numeral 28 denotes a rod guide, and the rod guide 28 is provided on a piston 29. The rod 26 is fitted into a piston 29, and the piston 29 is disposed slidably in the axial direction of the rod 26. The rod guide 28 is provided on the guide vane side of the inner periphery of the piston 29. A flange 30 is provided substantially at the center of the outer periphery of the piston 29. Piston 29
A case 31 is provided on the outer periphery of the electric servomotor body 4 and is fixed to the case 21 of the electric servomotor body 4. Piston 29
An oil seal member 32 is provided at a sliding position of the case 31 and oil is sealed from the oil tank 33 into the case 31. An oil passage 34 supplied from the oil tank 33 into the case 31 is branched in the middle, and a variable throttle 36 is provided in the middle of the branch passage 35. Reference numeral 37 denotes a spring. The spring 37 is interposed between the flange 30 and the case 31, and constantly urges the piston 29 rightward in the figure.

The electric servomotor main body 4 configured as described above is disposed between the control circuit 5 and the guide vane operation arm 3 as shown in FIG.

Next, the operation of the above embodiment will be described. When the guide vane is operated from the closed state to the open state by the electric servomotor body 4, the piston 29 of the dashpot 38 is urged by a spring 37 to the first right in the drawing (in the guide vane opening direction).
The 29 brim portion 30 comes into contact with the case 31 and stops. At this time,
The oil flows into the chamber containing the spring 37 via the variable throttle 36. The movable stroke S of the piston 29 is set to be equal to or less than the no-load opening of the turbine.

Although the piston 29 operates as described above, the electric servomotor
Is moved rightward in the figure. At this time, since the rod 26 is inserted into the piston 29, the rod 26 moves smoothly. For example, the normal operation of the electric servomotor body 4 has no effect because the linear speed of the servomotor is 20 to 30 mm / sec.

Here, when an abnormality occurs in the control circuit 5 or the like, the electric servomotor main body 4 operates to move the rod 26 rapidly to the left in the drawing in order to fully close the guide vanes. Then, the stopper 27 first collides with the piston 29 and the piston 29
Is pressed to the left in the drawing at the closing speed. Spring of piston 29
The oil in the chamber in which 37 is accommodated enters the right-hand chamber of the piston 29 through the variable throttle 36. Since the variable throttle 36 has the check valve portion 36a, the oil is throttled by the check valve portion 36a, so that the closing speed of the piston 29 is reduced as shown in FIG. That is, the mode becomes the gentle closing mode. This allows
Since the rod 26 abuts against the stopper ST of the electric servomotor main body 4 without colliding, the impact force is not applied to the servomotor main body 4 and the servomotor main body 4 is not broken. It should be noted that the buffer effect is generated only near the fully closed position (no load opening degree, that is, about 10% of the full stroke) of the electric servomotor body 4 when it is suddenly closed (the servomotor linear speed is 50 to 100 mm / sec).

In the above embodiment, since the rod guide 28 is provided at the right end in the figure of the piston 29, the distance between the fulcrums of the rod 26 can be increased, and the rigidity of the support of the rod 26 can be greatly improved. Become stronger.

In addition, the number of parts is reduced as compared with a case where a dash pot is separately installed, and the play of the movable portion and the deflection of the continuous portion are reduced.

Furthermore, since the dashpot operates within the no-load opening range, during normal operation, regardless of the dashpot,
Since it operates, there is no sliding of the seals of the dash pot, the friction of the seal is extremely small, and the life can be extended.

H. Effects of the Invention As described above, according to the present invention, when the main body of the electric servomotor is rapidly operated to close the guide vanes due to a control circuit or power supply abnormality, the stopper of the rod is moved to the collision buffer. When the collision occurs, the sudden closing speed of the electric servomotor can be reduced just before the guide vanes are fully closed by the action of the buffer oil, so that the impact can be reduced, thereby preventing the electric servomotor from being destroyed. Further, since the collision buffer is provided on the same axis as the rod, the installation space can be reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a configuration showing an embodiment of the present invention, FIG. 2 is an explanatory diagram of use of an electric servomotor, FIG. 3 is a characteristic diagram of an electric servo closing mode according to an embodiment of the present invention, and FIG. Schematic configuration diagram of electric servo motor, water wheel and control circuit,
FIG. 5 is a characteristic diagram of the conventional electric servo closing mode. 4 ... Electric servo motor body, 26 ... Rod, 27 ... Stopper, 28 ... Rod guide, 29 ... Dash pot piston, 30 ... Flange, 31 ... Dash pot case, 32
... Oil seal member, 33 ... Oil tank, 36 ... Variable throttle, 37 ... Spring.

Claims (1)

(57) [Claims] 1. A method in which a rod projected from an electric servomotor body and a guide vane operating portion of a water wheel are connected by a guide vane operating arm, and the guide vane of the water wheel is operated by the electric servomotor body. A rod protruding from the main body of the electric servomotor, a collision buffer body provided on the same axis as the rod and filled with a buffer oil in which the rod is movably fitted in the axial direction, and a tip of the rod And a stopper that collides with the collision buffer when the guide vane is fully closed.