JP2001140769A - Eccentric screw pump with single shaft and buffering method for stopping rotation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an eccentric screw pump with a single shaft suitable for long distance transfer and capable of preventing occurrence of a water hammer phenomenon by gradually reducing the speed of a rotor for stopping so as not to suddenly stop it, when stopping pump operation including the time of an unexpected power failure. SOLUTION: The driving shaft 15a of an electric motor 15 has another driving shaft 19 connected through a coupling 19a. Both ends of the driving shaft 19 are rotatably supported by bearing devices 20 and 20, and a flywheel 16 and five linked pulleys 17 having small diameters are mounted in this order to the axially intermediate position of the driving shaft 19 so that they can integrally rotate. The five linked pulleys 5 on the pump side and the five-train pulleys 17 on the motor side are connected by five endless belts 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for stopping the rotation of a uniaxial eccentric screw pump for transferring various kinds of conveyed substances such as liquid chemicals, solid-containing liquids, slurries, and high-viscosity liquids over a long distance. The present invention relates to a buffer rotation stop method for continuing the eccentric rotation of the male screw rotor for a while when the drive device stops due to a power failure or the like, and gradually stopping the rotation, and a uniaxial eccentric screw pump provided with the buffer rotation stop means. Things.

[0002]

2. Description of the Related Art In a single-shaft eccentric screw pump used for transferring a conveyed material such as liquid, sludge and dewatered cake over a long distance (for example, 10 to 20 km), as shown in FIG. In the eccentric screw pump 31, the spiral blade 3 is attached to a rotating shaft 33 provided at one end of a pump casing 32.
An end stud connected to the stator 36 by rotatingly eccentrically inserting a male threaded rotor 35 connected via a screw rod 34 around which the 4a is integrally rotatably attached and rotatably inserted into a female threaded stator 36. 36b
And the transported material D is transported over a long distance by a pipe 38 having one end connected to the discharge port 36a. An electric motor 40 is usually used as a driving device of the rotor 35, and a reduction gear 39 (a reduction gear device, a pulley and an endless belt, in this example, a pulley and a V-belt are attached to a drive shaft 33 supported by a bearing 37). ), The rotation of the electric motor 40 is transmitted, and the rotor 35 is rotated. Reference numeral 41 in the figure denotes a hopper, reference numeral 42 denotes a belt conveyor device, and reference numeral 43 denotes a cover for the reduction gear 39.

[0003]

In the case of transporting liquids and sludge, etc., over a long distance by the above-described conventional single-axis eccentric screw pump, there is no problem in the long-distance transport, but the following disadvantages occur. Should be improved. In other words, when the operation of the single-shaft eccentric screw pump is stopped, if the rotation of the rotor is suddenly stopped, the transferred object tries to move in the transfer direction because the inertial mass of the transferred object is large. This causes a water column separation and a negative pressure during that time, so-called water hammer phenomenon occurs.

[0004] Due to the water hammer phenomenon, an abnormal sound is generated, and the piping 38 (FIG. 4) and the pump 31 (particularly, the stator 36) are damaged.

If a variable speed motor such as an inverter motor or a servo motor is used for the drive device, the occurrence of the water hammer phenomenon can be prevented by performing the stop operation during normal operation while gradually lowering the rotation speed. Yes, but there is no way to prevent a sudden power outage. Moreover, the use of a variable speed motor such as a servomotor increases the cost of the entire apparatus.

[0006] A single-shaft eccentric screw pump for long-distance transfer requires a large-capacity large motor of several tens of kW, but a variable-speed motor such as a large-capacity servomotor is difficult to obtain. I have to use

[0007] Even when a general-purpose motor is used, a control device having a buffer stop function that electrically controls the motor so that the rotation speed of the motor gradually decreases and stops when the motor is stopped may be provided. Is expensive, and in the event of a sudden power failure, the buffer stop function does not work, causing a water hammer phenomenon.

The present invention has been made in view of the above points, and when the operation of the pump is stopped including a sudden power failure, the rotor is not suddenly stopped, in other words, is gradually decelerated and stopped. Accordingly, it is an object of the present invention to provide a uniaxial eccentric screw pump for transporting over a long distance and a method of stopping the buffer rotation thereof, which can prevent the occurrence of the water hammer phenomenon.

[0009]

In order to achieve the above object, a method of stopping the rotation of a single-shaft eccentric screw pump according to the present invention is achieved by eccentrically rotating a male-screw rotor of the single-shaft eccentric screw pump via a driving device. In the course of transporting the transported material over a long distance by a pipe connected to the discharge port of the female screw type stator, the rotor continues to be eccentrically rotated for a while due to inertial force when the driving device is stopped. And

According to the method of stopping the rotation of the single-shaft eccentric screw pump according to the present invention having the above-described configuration, even if the driving device suddenly stops operating due to a power failure, for example, the rotation of the rotor (single-shaft eccentric screw pump) is stopped. The rotation (operation) continues for a while due to the inertia force during normal rotation, and is gradually decelerated and stopped, so that the water hammer phenomenon can be reliably generated even during the long-distance transfer of the transferred object such as liquid or slurry liquid. Is prevented.

In order to achieve the above object, a single-shaft eccentric screw pump according to the present invention (described in claim 2) reduces the rotation of a drive shaft of an electric motor via a speed reduction device, and fits into a female screw type stator. In a single-shaft eccentric screw pump for transmitting eccentric rotation by transmitting to an inserted male screw rotor, a flywheel is attached to the drive shaft so as to be integrally rotatable.

According to the single-shaft eccentric screw pump according to the present invention having the above-described configuration, the power transmission to the electric motor is suddenly stopped not only when the power transmission to the electric motor is stopped during the normal operation but also when the power is stopped. In this case, the drive shaft of the electric motor continues to rotate due to the inertia force of the flywheel that had been rotating normally until then, and the rotational force is doubled via the reduction gear and transmitted to the male screw rotor. Since the operation of the pump is continued for a while, the transfer of the transferred object does not stop suddenly, and therefore, there is no possibility that the water hammer phenomenon occurs.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a single-shaft eccentric screw pump according to the present invention will be described with reference to the drawings, and a method of stopping a shock-absorbing rotation will be described. FIG. 1 is a side view, partially in section, showing one embodiment of a single-shaft eccentric screw pump.

As shown in FIG. 1, a single-shaft eccentric screw pump 1
Is a horizontal type. One end of a female screw type stator 11 is connected to one end of a pump casing 8, and an end stud 12 forming a discharge port is connected to the other end of the stator 11. The bearing unit 4 of the rotating shaft 2 is connected to the other end of the casing 8. The rotating shaft 2 is rotatably supported by a ball bearing 3 of a bearing unit 4, and a large-diameter five pulley 5 is integrally rotatable at an end of the rotating shaft 2 protruding outward from the bearing unit 4. It is attached to. On the upper surface of the casing 8, an opening 8a having a cylindrical or rectangular cylindrical shape forming an intake port and having an outwardly directed flange 8b at the upper end is projected upward, and a hopper 9 that gradually increases its opening area upward. An opening 9a having an outward flange 9b at the lower end is connected to the opening 8a.

Immediately above the hopper 9, a belt conveyor device 14 is provided, and a conveyed material, in this example, sludge D in this example is continuously charged into the hopper 9 by rotation of the conveyor belt 14a. An outward flange 12b is formed around the distal end opening 12a of the end stud 12, and
Outward flange 13b formed around one end opening
Are connected to the end studs 12 via the. In addition,
Although only a part of the pipe 13 is shown, it is 10 to 20 km.
In some cases, various metal pipes are used for the pipe 13 according to the type of the transferred object D and the transfer distance (discharge pressure).

The stator 11 is formed with a female screw-shaped hole 11a having an oval cross section and a pitch twice as large as that of the rotor 10, and the male screw rotor 10 having a circular cross section is turned in the female screw hole 11a. It is fitted movably and slidably in the long axis direction. One end of the rotor 10 (the pump casing 8 side) and one end of the rotating shaft 2 are connected via universal joints 14 by a screw rod 7 as a connecting rod in this example. Around the screw rod 7, a spiral blade 7a is formed so as to be integrally rotatable. A part of the rotating shaft 2 protrudes into the casing 8, and a mechanical seal 6 is mounted around the protruding portion to seal the shaft.

A general-purpose electric motor 15 is used for the driving device, and a driving shaft 15a of the electric motor 15 has a drive shaft 15a.
A separate drive shaft 19 is connected via a coupling 19a. The drive shaft 19 is rotatably supported at both ends by bearing devices 20 and 20. A flywheel 16 and a small-diameter five pulley 17 are attached to the drive shaft 19 at an intermediate position in the axial direction so that they can rotate integrally with each other. Have been. The five pulleys 5 on the pump side and the five pulleys 17 on the motor side are connected by five endless V-belts 18. In addition, each bearing device 20 is a ball bearing 20.
a and a bearing housing 20b for supporting the ball bearing 20a. In addition, pulley 5.17 and V
The belt 18 and the flywheel 16 are covered by a cover 21.
Is entirely covered by

The above configuration constitutes the single-shaft eccentric screw pump 1 according to the present embodiment. The pump 1 operates as follows.

In FIG. 1, a single-shaft eccentric screw pump 1 starts rotation of an electric motor 15 to
The rotation is transmitted to the rotating shaft 2 after being decelerated via 5, and the rotor 10 rotates via the universal joint 14, the screw rod 7, and the universal joint 14. Since the rotation of the electric motor 15 requires the flywheel 16, the rotation speed gradually increases after the start.
Due to the rotation of the rotor 10, the sludge D put into the casing 8 is transferred through the front pipe 13. In the casing 8, the sludge D conveyed by the belt conveyor device 14 falls from the hopper 9 and is thrown in. The sludge D is conveyed to the front stator 11 by the spiral blade 7a of the screw rod 7. You. In this way,
Sludge D is continuously discharged from the stud 12 at the tip of the stator 11 and is transferred to a predetermined place through the pipe 13.

On the other hand, the electric motor 1
When the power transmission to the motor 5 is interrupted, or when the switch (not shown) of the electric motor 15 is turned off during normal operation, the drive shaft 15 a of the electric motor 15 rotates for a while due to the inertial force of the flywheel 16. continue. During this time, the rotational force of the drive shaft 15a due to the inertial force of the flywheel 16 is doubled via the pulley 17, the V-belt 18, and the pulley 5, and transmitted to the rotary shaft 2, whereby the screw rod 7 and the rotor 10 continue to rotate. However, the drive shaft 15a
Since the inertial force transmitted from the shaft to the rotating shaft 2 is doubled, the rotor 10 continues to rotate smoothly under a large inertial force as compared with the case where the flywheel 16 is attached to the rotating shaft 2 on the rotor 10 side. Therefore, the transfer operation of the sludge D is reliably continued. Then, the rotation of the rotor 10 and the like gradually decreases and stops. Therefore, the water hammer phenomenon caused by the sudden interruption of the transfer does not occur.

Although not limited, in the above embodiment, the moment of inertia (GD ² ) = 0.5 kgm
² is used on the electric motor 15 side and the reduction ratio of the pulley 17 / pulley 5 is set to 1/4, so that the moment of inertia (β · GD) acting on the rotary shaft 2 and the rotor 10 on the pump side is set. ² ) is 0.5 × 4 ² = 0.5 × 16 = 8 kgm ² , which is 16 times (β) of the square of the reduction ratio. Since the rotor 10 of the single-shaft eccentric screw pump 1 is generally small in diameter and long in the longitudinal direction, the inertia force (moment) is very small, and the stator 11 is usually made of rubber.
Due to the friction loss between the rotor 10 and the rotor 10, rotation by the inertial force of the rotor 10 itself (inertial rotation) after the electric motor 15 is stopped cannot be expected much. Therefore, the effect of attaching the flywheel 16 to the electric motor 15 is extremely large.

FIG. 2 shows another embodiment of the single-shaft eccentric screw pump of the present invention. The single-shaft eccentric screw pump 1 'of this embodiment differs from the above-described embodiment in the following points. That is, as shown in FIG. 2, a reduction gear 22, a bearing device 20, a flywheel 16, a bearing device 20, and an electric motor 15 are installed in this order on an extension of the rotary shaft 2 of the single-shaft eccentric screw pump 1 '. Coupling 19a ・ 20a ・ 2
It is connected in series through 2a. In the case of the present example, a long and narrow installation space is required. However, the operation mode of the single-shaft eccentric screw pump 1 ′ is substantially the same as that of the above-described single-shaft eccentric screw pump 1, and therefore the description thereof is omitted. Note that members common to the above-described embodiments are illustrated using the same reference numerals. FIG. 3 shows still another embodiment of the single-shaft eccentric screw pump of the present invention.
Are different from the pump 1 'of the second embodiment in the following points. That is, in order to reduce the installation space in the longitudinal direction, a double-shaft electric motor 15 'with a reduction gear 23 is used, and the rotating shaft 2 and the drive shaft 23a of the reduction gear 23 are connected via a coupling 23b. The flywheel 16 is mounted on the drive shaft 23 c on the opposite side of the electric motor 15 ′ so as to be integrally rotatable, and the periphery of the flywheel 16 is covered by a cover 24. In the case of this example, the installation space is shorter than that of the single-shaft eccentric screw pump 1 'of the second embodiment, but the operation mode of the single-shaft eccentric screw pump 1 "is the same as that of the second embodiment. The description is omitted because it is substantially the same as'. The members common to the above embodiment are shown using the same reference numerals.

Although the embodiment of the single-shaft eccentric screw pump of the present invention has been described above, the present invention can be implemented as follows.

Although the flywheel 16 is provided on the drive shaft 19 on the same axis as the drive shaft 15 a of the electric motor 15,
For example, a flywheel 16 is provided by disposing an intermediate drive shaft at an intermediate position between the drive shaft 15a and the rotary shaft 2, and the rotation of the intermediate drive shaft is transmitted to the rotary shaft 2 via a reduction gear such as a reduction gear. It may be.

For example, a pin joint can be used in place of the universal joint 14. In addition, since the mechanical seal 6 is employed, there is an advantage that periodic retightening work is not required. However, a gland packing may be used as a seal member.

A hydraulic motor is used for the driving device, and a control means having a buffer rotation stop function is incorporated in the hydraulic circuit. That is, for example, in a hydraulic circuit for driving the hydraulic motor, a flow control valve (or a throttle valve) for a large flow rate that rotates the hydraulic motor at high speed during normal operation, and a low-speed rotation of the hydraulic motor when the rotation of the hydraulic motor stops. A flow control valve (or throttle valve) for a small flow rate, a switching valve for switching between a flow control valve (or a throttle valve) for a large flow rate and a small flow rate, and an accumulator for accumulating oil pressure are provided, and rotation of the rotor is stopped. At times, the flow control valve (or throttle valve) for small flow is switched by the switching valve so that the pressure oil flows, and the hydraulic motor is rotated at a low speed by the oil pressure accumulated in the accumulator, and then the rotation is stopped. be able to.

[0027]

As is apparent from the above description,
Advantageous Effects of Invention The uniaxial eccentric screw pump and the method of stopping the rotation of the buffer according to the present invention have the following excellent effects.

(1) According to the first aspect of the invention, even when the drive device suddenly enters a stop operation state due to a power failure, the rotation of the rotor continues for a while due to the inertial force, and is gradually decelerated and stopped. Therefore, the occurrence of the water hammer phenomenon can be reliably prevented even during the long-distance transfer of the transferred object such as the liquid and the slurry, and the piping and the pump can be prevented from being damaged.

(2) According to the second aspect of the present invention, not only when the power transmission to the electric motor is stopped during the normal operation, but also when the power transmission to the electric motor is suddenly stopped at the time of the stop, etc. The drive shaft of the electric motor continues to rotate due to the inertia force of the flywheel, which has been rotating, and the rotational force is doubled via the reduction gear and transmitted to the male screw type rotor, so that the operation of the pump is ensured for a while. Since the transfer is continued, the transfer of the transferred object does not stop suddenly, and the water hammer phenomenon does not occur. Moreover, it has a simple structure in which a flywheel is provided, and its manufacturing cost is almost the same as the conventional one.

Further, since the flywheel is provided on the electric motor side to transmit the rotation to the rotor via the reduction gear, the rotor of the single-shaft eccentric screw pump is generally small in diameter and long in the longitudinal direction. Moment) is very small, but after the electric motor is stopped, the moment of inertia by the flywheel is doubled to several tens of times and transmitted to the rotor. After the stop, the rotation of the rotor surely continues for a while.

[Brief description of the drawings]

FIG. 1 is a sectional side view showing a part of a single-shaft eccentric screw pump according to an embodiment of the present invention.

FIG. 2 is a side view, partially in section, showing a single-shaft eccentric screw pump according to a second embodiment of the present invention.

FIG. 3 is a side view, partially in section, showing a single-shaft eccentric screw pump according to a third embodiment of the present invention.

FIG. 4 is a side view, partially in section, showing a conventional general single-axis eccentric screw pump for long-distance transfer.

[Description of Signs] 1 ・ 1 ′ ・ 1 ″ Uniaxial Eccentric Screw Pump 2 Rotary Shaft 4 Bearing Unit 5 ・ 17 Pulley (Reduction Gear) 7 Screw Rod 8 Pump Casing 10 Rotor 11 Stator 13 Piping 14 Universal Joint 15.15 ′ Electric Motor (drive device) 15a / 19 Drive shaft 16 Flywheel 18 Endless V-belt 20 Bearing device 22/23 Reduction device

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Natsushiro Ureshino 1-54, Misakihoncho, Hyogo-ku, Kobe-shi, Hyogo F-term (reference) 3H041 AA03 AA04 BB06 CC11 CC18 DD05 DD07 DD10 DD31 3H044 AA03 AA04 BB04 CC11 CC18 DD05 DD06 DD18 DD19 DD21

Claims (2)

[Claims] 1. The method according to claim 1, wherein the male screw rotor of the uniaxial eccentric screw pump is eccentrically rotated via a driving device, and the transferred material is transported over a long distance by a pipe such as a hose connected to a discharge port of the female screw stator. A method of stopping the rotation of a single-shaft eccentric screw pump, wherein the rotor continues eccentric rotation for a while due to inertial force when the apparatus is stopped. 2. A single-shaft eccentric screw pump in which the rotation of a drive shaft of an electric motor is reduced via a speed reducer, transmitted to a male screw rotor inserted into a female screw stator and eccentrically rotated. A single-shaft eccentric screw pump characterized in that a flywheel is mounted so as to rotate integrally.