JPH1047279A - Two-stage pump device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of cavitation, and avoid generation of a noise and a cause of failure by arranging a fixed volume pump on the delivery side of a centrifugal pump, arranging a pressure adjusting valve between the delivery side of this fixed volume pump and the delivery side of the centrifugal pump, and integrally constituting the centrifugal pump, the fixed volume pump and the pressure adjusting valve. SOLUTION: A cascade type impeller 12 is fixed by a key 13 to a rotary shaft 10 in a housing 11 of a centrifugal pump 1, and an inner roller 15 and an outer roller 16 are arranged in a housing 14 of an internal gear pump 2, and the inner roller 15 is fixed to the rotary shaft 10 by a key 17. The centrifugal pump 1 and the internal gear pump 2 are formed as an integral structure by connecting its housings 11 and 14 to each other by a bolt 19 together with a cover 18. A pressure adjusting valve 3 is fixed to the housing 11 of the centrifugal pump 1 by a bolt, and is also formed as an integral structure. A flange in which the housing 14 of the internal gear pump 2 is arranged is fixed by a bolt 22 to a motor flange 21 of an electric motor to drive the rotary shaft 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pump device suitable for sending a refrigerant in an apparatus using a refrigerant or the like.

[0002]

2. Description of the Related Art In such a device, a single-stage pump device such as a constant volume pump or a centrifugal pump has conventionally been used as a coolant sending device.

[0003]

When a conventional one-stage pump device is used to feed a refrigerant, a constant-volume pump generates cavitation due to the low boiling point of the refrigerant, causing noise and failure. . In addition, with only a centrifugal pump, the pump input becomes very large when high pressure is used, and a motor with a large output is required.

Therefore, a combination of a centrifugal pump having a large discharge rate and a constant volume pump capable of obtaining a high pressure is conceivable. However, there has been no time-consuming connection of the two pipes, and there has been a problem of leakage.

Accordingly, the present invention prevents cavitation and reduces the driving horsepower of the pump.
The object of the present invention is to provide a two-stage pump device that does not require time for pipe connection and the like.

[0006]

According to the present invention, a constant volume pump is provided on the discharge side of a centrifugal pump, and a pressure regulating valve is provided between the discharge side of the constant volume pump and the discharge side of the centrifugal pump. , The centrifugal pump, the constant volume pump, and the pressure regulating valve are integrally configured.

According to the present invention, the constant displacement pump is an internal gear pump.

According to the present invention, the centrifugal pump is a centrifugal pump using a spiral impeller.

Alternatively, according to the present invention, the centrifugal pump is a centrifugal pump using a cascade type impeller.

In the pump device configured as described above, the centrifugal pump becomes a booster pump and the suction pressure of the constant volume pump becomes plus (+) pressure, so that cavitation can be prevented. The suction pressure of the constant volume pump can be increased by increasing the capacity of the centrifugal pump. Further, since the centrifugal pump, the constant volume pump and the pressure regulating valve are integrated, there is no need for troublesome pipe connection and no inconvenience such as leakage occurs.

[0011]

FIG. 1 shows a circuit of a two-stage pump apparatus according to the present invention. A first-stage centrifugal pump 1 having a larger discharge rate than a constant volume pump is provided upstream of a pipe L. .
On the discharge side of the centrifugal pump 1, a constant volume pump, in the illustrated example, an internal gear pump 2 is provided, and the displacement between the discharge side of the constant volume pump 2 and the discharge side of the centrifugal pump 1 is adjusted. A pressure valve 3 is provided. The impeller 12A of the centrifugal pump 1 is shown as a spiral type in the example shown in FIG. 1, but may be a cascade type impeller 12 as shown in FIG. 2 or another type.

A liquid is drawn from a tank (not shown) through a suction pipe inlet A into a suction port of a centrifugal pump 1, and the liquid pressurized by the centrifugal pump 1 is sent to a suction port of a constant volume pump 2 by pressure. The pressure is further increased by the volume pump 2 and discharged from the discharge port B. When the discharge pressure of the constant volume pump 2 becomes equal to or higher than the specified pressure, the pressure regulating valve 3 is operated, and the liquid returns between the centrifugal pump 1 and the constant volume pump 2.

FIGS. 2 and 3 show a two-stage pump device in which the centrifugal pump 1, the constant volume pump 2, and the pressure regulating valve 3 are integrally formed. In a housing 11 of the centrifugal pump 1, a cascade type impeller 12 is fixed to a rotating shaft 10 integrally with a key 13 by a key 13 in the illustrated example. Further, an inner roller 15 and an outer roller 1 are provided in a housing 14 of a constant volume pump, in the illustrated example, an internal gear pump 2.
The inner roller 15 is fixed to the rotary shaft 10 by a key 17 so as to rotate integrally therewith. And
The centrifugal pump 1 and the internal gear pump 2 have a housing 1
1 and 14 are connected together with a cover 18 by bolts 19 to form an integral structure. Further, the pressure regulating valve 3 is also fixed to the housing 11 of the centrifugal pump 1 by bolts 20 to form an integral structure. A motor flange 21 of an electric motor for driving the rotating shaft 10 is fixed to a flange provided with the housing 14 of the internal gear pump 2 by a bolt 22.

2, reference numeral 23 denotes a radial bearing, 24 denotes a bearing bush, 25 denotes a radial bearing, and 26 denotes a thrust bearing. 27 and 28 are magnetic couplings, and 29 is a coupling cover.

As described above, the integral construction of the centrifugal pump 1, the constant volume pump 2, and the pressure regulating valve 3 eliminates the need for piping connection, facilitates handling, and causes inconvenience such as leakage of liquid. Absent.

[0016]

The centrifugal pump becomes a booster pump, so that the suction pressure of the constant volume pump becomes plus (+) pressure, thereby preventing the occurrence of cavitation and avoiding the noise and the cause of failure. Further, by using a constant displacement pump that generates a high pressure, a pump device having a small driving horsepower of the pump can be provided.

Since the centrifugal pump, the constant volume pump, and the pressure regulating valve are integrally formed, there is no need for troublesome pipe connection, easy handling, and no inconvenience such as liquid leakage.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a two-stage pump device including a centrifugal pump and a constant volume pump.

FIG. 2 is a longitudinal sectional view of a two-stage pump device according to the embodiment of the present invention.

FIG. 3 is a front view of the two-stage pump device shown in FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Centrifugal pump 2 ... Constant volume pump 3 ... Pressure regulating valve 10 ... Rotary shaft 11 ... Centrifugal pump housing 12, 12A ... Impeller 14 ... Constant volume pump housing 15 ... Inner rotor 16 ... Outer rotor 18 ... Cover 19,20,22 ... Bolt 21 ... Motor flange

Continued on the front page (72) Inventor Hiroharu Nakazawa 825 Urushiyama, Nanyo-shi, Yamagata

Claims (4)

[Claims] 1. A constant volume pump is provided on the discharge side of a centrifugal pump, and a pressure regulating valve is provided between the discharge side of the constant volume pump and the discharge side of the centrifugal pump. And a two-stage pump device. 2. The two-stage pump device according to claim 1, wherein the constant displacement pump is an internal gear pump. 3. The two-stage pump device according to claim 1, wherein the centrifugal pump is a centrifugal pump using a spiral impeller. 4. The two-stage pump device according to claim 1, wherein the centrifugal pump is a centrifugal pump using a cascade type impeller.