JPH07243392A - Pump unit - Google Patents

Abstract

PURPOSE:To prevent the size of a pump unit from increasing by serial- connecting and operating a motor pump through commercial power driving and a motor pump which can be variably-operated with a frequency converter for corresponding to the operation of both the motor pumps according to a small, medium and large amount of water. CONSTITUTION:This pump unit is constituted by serial-connecting a motor pump A through commercial power driving and a motor pump B which can be variably-operated with a frequency converter 50. The motor pumps A, B are full circumference flow type motor pumps of the same structure, and the suction 4a of the motor pump A and the suction 3a of the motor pump B are connected with each other through flanges 53, 54. In the case of a small amount of water, the motor pump B is operated independently at a prescribed speed with the frequency converter 50. In the case of a medium amount of water, the motor pump A is operated independently. In the case of a large amount of water, the motor pump A is always operated and the motor pump B is operated at a prescribed speed. It is thus possible to provide operation control without any uselessness and reduce the size of a pump body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pump unit,
Particularly, the present invention relates to a pump unit that is operation-controlled in response to changes in flow rate and discharge pressure that are required.

[0002]

2. Description of the Related Art A pump unit is known in which the discharge pressure is controlled to be constant regardless of the amount of water supplied. For example, there is known a pump unit that controls the number of rotations of one motor pump according to the change in the water supply amount. In such a pump unit, since a pump having a large rated shaft power (motor output) is operated at a variable speed, a frequency converter (for example, an inverter) having a large load capacity is required.

[0003]

The conventional pump unit requires a frequency converter having a large load capacity as described above, which causes a problem of high cost.
Further, if the frequency converter fails, the water supply function of the pump unit becomes zero.

The present invention has been made in view of the above-mentioned circumstances, and a load of a frequency converter is obtained by connecting a motor pump driven by a commercial power source and a motor pump capable of variable speed operation by a frequency converter in series. It is an object of the present invention to provide a pump unit that can reduce the capacity to reduce the cost and can secure a minimum amount of water supply even if the frequency converter fails. It is another object of the present invention to provide a pump unit that can prevent an increase in the size of the device due to an increase in the number of devices by devising and using an all-circumferential type pump as the pump itself.

[0005]

In order to achieve the above object, the present invention provides a motor pump driven by a commercial power source,
It is characterized in that a motor pump capable of variable speed operation is connected in series by a frequency converter for operation.

[0006]

According to the present invention, a motor pump driven by a commercial power source and a motor pump driven at a variable speed by a frequency converter are connected in series and operated. The operation will be shown below in different cases. (1) Small amount of water The motor pump B operated by the frequency converter is operated independently at a predetermined rotation speed. (2) In the case of medium water volume The motor pump A driven by the commercial power supply is operated independently. (3) Large amount of water The motor pump A is always operated, and the motor pump B is operated at a predetermined rotation speed. By controlling in this way, even if the capacity of the frequency converter is equivalent to one pump, it is possible to perform operation control without waste for all the amount of water supply.

Further, according to the present invention, the pump main body is miniaturized by making the pump a full-circumferential flow type and making the cooling condition of the motor good, thereby preventing the enlargement of the apparatus accompanying the connection of a plurality of units. . Further, the present invention connects the fastening portion for fixing the discharge casing of the outer cylinder of the pump located in the preceding stage and the fastening portion for fixing the suction casing of the outer cylinder of the pump located in the latter stage with the connecting short pipe, and the connecting short pipe. The pipe is provided with a partition wall. By doing so, a plurality of pumps can be connected in series with a relatively small size, and the pump unit can be compactly assembled.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a pump unit according to the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the pump unit of the present invention. As shown in FIG. 1, the pump unit includes a motor pump A driven by a commercial power source and a frequency converter (inverter) 50.
Therefore, the motor pump B capable of variable speed operation is connected in series. The motor pumps A and B are all-circumferential-type motor pumps, and the discharge port 4a of the motor pump A and the suction port 3a of the motor pump B have a flange 5.
They are connected by fastening 3,54.

Since the motor pump A and the motor pump B have exactly the same structure, only the structure of the motor pump A will be described below.

The motor pump A is a pump casing 1.
And a canned motor 6 housed in the pump casing 1, and impellers 8 and 9 fixed to a main shaft 7 of the canned motor 6. The pump casing 1 is composed of a pump casing outer cylinder 2, a suction casing 3 and flanges 51 and 52, which are connected to both ends of the pump casing outer cylinder 2, respectively, and a discharge casing 4. The pump casing outer cylinder 2, the suction casing 3, and the discharge casing 4 are made of sheet metal such as stainless steel.

The first stage impeller 8 is housed in a first inner casing 10 having a return vane 10a, and the second stage impeller 9 is contained in a second inner casing 11 having a guide device 11a. There is. Further, an elastic seal 12 is interposed between the first inner casing 10 and the suction casing 3.
A liner ring 45 is provided at the inner ends of the first and second inner casings 10 and 11.

On the other hand, the canned motor 6 includes, as shown in FIG. 1, a stator 13, a motor frame outer body 14 fitted to the outer peripheral portion of the stator 13, and both open ends of the motor frame outer body 14. Motor frame side plate 1 welded and fixed to
5 and 16 and a can 17 fitted to the inner peripheral portion of the stator 13 and welded and fixed to the motor frame side plates 15 and 16. A rotor 18 rotatably housed in the stator 13 is shrink-fitted and fixed to the main shaft 7.
A cable housing 20 is provided on the outer frame 14 of the motor frame.
Are fixed by welding, and the motor frame outer case 1
The lead wire is pulled out from the coil in the cable 4 and is connected to the power cable 46 in the cable housing 20.

The cable housing 20 has an open end 20a.
Has a cup shape with a bottom 20b and an open end 20
a is hermetically welded to the outer frame 14 of the motor frame, and the bottom portion 20b
A hole 20c for passing the lead wire is formed in the.

A hole 2a is formed in the outer cylinder 2,
The cable housing 20 is inserted into the hole 2a,
The outer cylinder 2 and the cable housing 20 are hermetically welded. A cable connector 41 for holding a cable 55 is inserted into a lead wire passage hole 20c formed in the bottom portion 20b of the cable housing 20, and the cable connector 41 and the cable housing 20 are fixed by welding. .

Next, the bearing peripheral portion on the anti-thrust load side will be described. The bearing bracket 21 includes a radial bearing 2
2 and a fixed thrust bearing 23 are provided. The end surface of the radial bearing 22 also has a function as a fixed-side thrust sliding member. On both sides of the radial bearing 22 and the fixed thrust bearing 23, a rotary thrust bearing 24, which is a rotary thrust sliding member, and a thrust collar 2 are provided.
5 are provided. The rotation side thrust bearing 24 is fixed to the thrust disk 26, and the thrust disk 2
6 is fixed by a screw and a nut 28 provided at the end of the main shaft 17 via a sand guard 27.

The bearing bracket 21 is inserted into a spigot provided on the motor frame side plate 16 via an O-ring 29 made of an elastic material. Bearing bracket 2
1 is in contact with the motor frame side plate 16 via a gasket 30 made of an elastic material. Reference numeral 31 in the drawing denotes a sleeve which forms a sliding portion with the radial bearing 22.

Next, the peripheral portion of the bearing on the thrust load side will be described. The bearing bracket 32 includes a radial bearing 3
3 is provided. In the figure, 34 is a sleeve that forms a sliding portion with the radial bearing 32, and the sleeve 34 is a washer 3
5, the washer 35 is fixed via the impeller 9, the sleeve 42, and the impeller 8 by the screw and nut 36 provided at the end of the main shaft 7. The bearing bracket 32 is inserted into a spigot provided on the motor frame side plate 15 via an O-ring 37 made of an elastic material. The bearing bracket 32 is in contact with the motor frame side plate 15.

Next, the operation of the pump unit constructed as described above will be described. According to the invention, the motor pump A
And the motor pump B, which is operated at a variable speed by the frequency converter 50, are connected in series and operated. The operation will be shown below in different cases with reference to FIG. FIG. 2 is a diagram showing a relationship between the water supply amount and the discharge pressure and a relationship between the water supply amount and the shaft power. (1) In case of small amount of water The motor pump B operated by the frequency converter 50 is independently operated at a predetermined rotation speed. (2) In the case of medium water volume The motor pump A driven by the commercial power supply is operated independently. (3) In the case of a large amount of water The motor pump A is constantly operated, and the motor pump B is operated at a predetermined rotation speed. By controlling in this way, even if the capacity of the frequency converter 50 is equivalent to one pump, it is possible to perform operation control without waste for all water supply amounts. Further, according to the present invention, the pump main body is miniaturized by making the pump a full-circulation type and improving the cooling condition of the motor, and it is possible to prevent the apparatus from becoming large due to the connection of a plurality of units. .

FIG. 3 is a diagram showing another embodiment of the pump unit of the present invention. In this embodiment, the connecting portion for connecting the discharge casing of the outer cylinder of the motor pump A located in the preceding stage and the engaging portion for fixing the suction casing of the outer cylinder of the motor pump B located in the subsequent stage are connected by the connecting short pipe 56. is doing. Further, the connecting short pipe 56 is provided with a partition wall 57 for partitioning the pump discharge pressure of the former stage and the pump discharge pressure of the latter stage.

In the present embodiment, the fastening portion for fixing the discharge casing of the outer cylinder 2 of the motor pump A located at the preceding stage,
The fastening portion for fixing the suction casing of the outer cylinder 2 of the motor pump B located at the latter stage is connected by the connecting short pipe 56, and the connecting short pipe 56 is provided with a partition wall 57. By doing so, a plurality of pumps can be connected in series with a relatively small size, and the pump unit can be compactly assembled. The other structure is the same as that of the embodiment shown in FIG. 1, and the function and effect are also the same.

[0021]

As described above, according to the present invention, the effects listed below can be obtained. It is possible to operate without waste according to each water supply amount without increasing the capacity of the frequency converter. Even if the frequency converter breaks down, water can be supplied by the pump driven by the commercial power supply, and the situation where the water supply function of the pump unit becomes zero can be prevented. Multiple pumps can be compactly connected in series.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a pump unit according to the present invention.

FIG. 2 is an explanatory diagram illustrating an operation of the present invention.

FIG. 3 is a sectional view showing another embodiment of the pump unit according to the present invention.

[Explanation of Codes] 1 pump casing 2 outer cylinder 3 suction casing 4 discharge casing 6 canned motor 7 main shaft 8,9 impeller 13 stator 14 motor frame outer shell 15,16 motor frame side plate 17 can 18 rotor 20 cable housing 21 , 32 Bearing brackets 22, 33 Radial bearings 23 Fixed thrust bearings 24 Rotational thrust bearings 45 Liner rings 50 Frequency converters 56 Connection short pipes 57 Partition walls

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Keita Uei 4-2-1 Honfujisawa, Fujisawa City, Kanagawa Prefecture EBARA Research Institute

Claims (3)

[Claims] 1. A pump unit comprising a motor-pump driven by a commercial power supply and a motor-pump capable of variable speed operation by a frequency converter, which are connected in series to operate. 2. The motor pump comprises a motor frame fitted to a motor stator and an outer cylinder forming an annular flow path on the outer periphery of the motor frame, and a suction casing and a discharge at both axial ends of the outer cylinder. Consists of an all-circumferential flow pump with a fastening part that fixes the casing. The pump unit according to claim 1, wherein the connecting short pipe is connected and a partition wall for partitioning the pump discharge pressure of the former stage and the pump discharge pressure of the latter stage is provided in the connecting short pipe. 3. A pump unit that is operation-controlled in response to required changes in flow rate and discharge pressure, and operates only a motor pump capable of variable speed operation with a frequency converter in a small output range, and outputs a medium output. 3. The pump unit according to claim 1, wherein only the motor pump driven by the commercial power supply is operated in the region, and both of the two types of pumps are operated in the high output region.