JPH0730951Y2 - Screw-centrifugal pump - Google Patents

Description

[Detailed Description of the Invention] (Industrial field of application) The present invention relates to a screw centrifugal pump, in particular, a screw centrifugal pump that achieves both high flow rate in forward rotation and high head in reverse rotation by forward and reverse rotation of a screw impeller. Related to improved technology.

(Prior Art) For simplification of the entire system, as a system in which one pump is used as a forward flow in forward rotation and a reverse flow in reverse rotation, a boiling cooling system for an internal combustion engine previously proposed by the applicant (actual application) Sho 59-146598 (Shokai Sho 61-63422) is known.

In this system, a cascade pump is shown as the forward / reverse pump.

(Problems to be solved by the invention) However, in the pump used in the boiling cooling system described above, page 4, line 6 to page 15 of the prior application specification.
As described in the line, there is a problem that cavitation occurs at high water temperature and the flow rate decreases.

Further, as described on page 8, line 4 to page 14, line 14 of the prior application, while securing the pumping amount of steam condensate water which corresponds to the heat generation amount of the engine during normal rotation of the pump. During reverse rotation of the pump, it is necessary to secure the pressure for expelling the air in the system during cold start of the engine.

From the above, the performance required for the pump used in the boiling cooling system is the following three points.

Strong against cavitation and less decrease in flow rate at high water temperature.

It must have a high flow rate characteristic that can secure the pumping amount of the condensed water of the steam at the forward rotation normal flow which is the main usage condition of the pump.

Although the pump is used for a short period of time, it must have a high head characteristic enough to secure the pressure for expelling the air in the system during reverse rotation and reverse flow.

That is, the required performances of and are illustrated in FIG.

Therefore, we started to develop a pump that satisfies the above-mentioned required performance by using a screw centrifugal pump that satisfies the above-mentioned required performance. The development process is described below.

(1) As shown in FIG. 7, two screw impellers are combined to form a drum shape (Japanese Patent Application No. 60-2504 (Japanese Patent Application Laid-Open No. Sho 60-2504).
61-160594)).

In this case, the forward rotation normal flow characteristic and the reverse rotation reverse flow characteristic of the flow rate-head are the same, and even if the reverse rotation reverse flow performance of can be cleared, there is a limit to the forward rotation normal flow performance mainly used, It is not possible to satisfy the required performance in forward rotation normal flow.

In the figure, the solid line indicates the performance during forward rotation and forward flow, and the broken line indicates the performance during reverse rotation and reverse flow (the same applies hereinafter).

(2) As shown in FIG. 8, a single screw impeller is used.

Focusing on the fact that the normal rotation positive flow is the main condition for using the pump, the end outer diameter ratio (end outer diameter ratio is the large diameter end outer diameter φD /
When the small diameter end outer diameter φd) is set to a large value to secure the forward rotation positive flow performance, the forward rotation forward flow performance is secured more than necessary, but the flow rate and the lift during reverse rotation reverse flow are extremely high. It is too small to meet the required performance.

(3) As shown in FIG. 9, the end outer diameter ratio is tuned.

In order to improve the drawback in the case of the above (2), the end portion outer diameter ratio is set small.

In this case, as the outer diameter ratio of the end is reduced,
Since there is a decrease in performance during forward rotation normal flow, there is a tuning limit up to the end outer diameter ratio that satisfies the required performance for forward rotation normal flow, as shown in Fig. 9. The outer diameter ratio does not reach the performance of reverse rotation and reverse flow (maximum head).

(4) As shown in FIG. 10, the pump in which the water flow collides with the tip (winding start portion) of the impeller at the end outer diameter ratio of (3).

In this case, as shown in the flow rate-head characteristics, if the fluid inlet is set so that the flow from the inlet collides with the tip of the screw impeller at the time of forward rotation, the amount of pushing in the pitch direction of the impeller at the time of forward rotation increases. Although there is some improvement in performance, during reverse rotation reverse flow, this fluid inlet serves as a discharge port, and the flow direction and discharge direction of the fluid are opposite, and the performance (head) during reverse rotation reverse flow decreases.

(5) As shown in FIG. 11, a pump that prevents the water flow from colliding with the tip of the impeller at the end outer diameter ratio of (3).

In this case, due to the opposite reason to the above, as shown in the flow rate-head characteristics, the performance during normal rotation and normal flow is reduced, but the performance during reverse rotation and reverse flow (head) is improved.

However, it does not reach the required performance (lift) for reverse rotation and reverse flow.

(6) As shown in FIG. 12, a chamber is formed by the pump of (5).

In order to further improve the head during reverse rotation reverse flow, a large volume that converts the kinetic energy of the fluid sent at the pitch of the impeller into pressure energy during reverse rotation reverse flow (the larger the volume, the higher the pressure of the discharged fluid can be increased. ) Chamber is required. By forming the chamber of this large volume, as shown in the flow rate-head characteristic of FIG. 12, the high head required at the time of reverse rotation and reverse flow is secured.

However, as described above, the clearance between the upper end of the impeller and the pump casing becomes large due to the need to increase the volume of the chamber. Around the impeller, a rotating revolving flow is generated, and a part of this recirculating flow is a flow that is not affected by the impeller's axial feed action, and this causes a loss in the impeller action. As a result, it was found that the flow rate required for the normal rotation forward flow, which was ensured in the case of (5) above, could not be secured.

(Means for Solving Problems) The present invention is to solve such conventional problems, that is, strong against cavitation, less decrease in flow rate at high water temperature, and high flow rate characteristic at forward rotation normal flow. It is an object of the present invention to provide a forward / reverse pump that also achieves a high head characteristic during reverse rotation and reverse flow.

To achieve this object, in the screw centrifugal pump of the present invention, the forward / reverse rotation motor, the screw impeller attached to the forward / reverse rotation motor, the outer circumference and both ends of the screw impeller are covered, and both end portions of the screw impeller are covered. In a screw centrifugal pump having a pump casing in which a fluid inlet / outlet is formed, the screw impeller is single, and its end outer diameter ratio is small so as to suppress deterioration of reverse rotation backflow performance. The inlet and outlet are opened tangentially to the rotation direction of the screw impeller so that a forward rotation forward flow and a reverse rotation reverse flow can be obtained without the flow from the inlet and outlet colliding. A chamber is formed on the small outer diameter end side of the screw impeller on the outlet side, and the ring in the chamber on the inlet side at the time of forward rotation normal flow is formed. A notch for receiving the flow is arranged on the inner surface of the pump casing at the end of the circulation when the inlet / outlet is the beginning of the circulation, and the notch redirects the circulation to the axial flow of the screw impeller. A deflecting surface was formed.

(Function) During forward rotation normal flow, the fluid that flows in from the side of the inlet / outlet with the smaller outer diameter of the impeller is sent by the centrifugal force and the pitch of the impeller, and the circular flow that tries to rotate around in the chamber is generated by the notch. It exhibits the action of being received, and in addition, the deflecting surface of the notch diverts the recirculation current to an axial flow.

As a result, there is almost no fluid that circulates in the chamber, there is no loss in the axial feed action of the screw impeller with respect to the fluid, and the required pump flow rate is ensured by improving pump efficiency. Since the notch is provided at the end position of the recirculation when the inlet / outlet is the recirculation start part, the fluid is completely sucked into the chamber to receive the fluid. There is no obstacle.

Reverse rotation During reverse flow, the fluid that flows in from the inlet / outlet side with the large outer diameter of the impeller is not sent to the centrifugal force of the fluid and is sent only at the pitch of the screw impeller. The given kinetic energy is converted into pressure energy and is discharged from the side of the inlet / outlet having the smaller outer diameter of the impeller, and the required lift is secured.

Embodiment An embodiment of the present invention will be described in detail below with reference to the drawings.

As shown in FIG. 1, the screw centrifugal pump A of this embodiment mainly includes a forward / reverse rotation motor 1, a screw impeller 2, a pump casing 3, and notches 4 and 5.

The forward / reverse rotation motor 1 is a thin electric motor that can be switched between forward rotation and reverse rotation by a switch, is fixed to one end surface of the pump casing 3, and has a motor shaft 11
Are extended inside the pump casing 3.

The screw impeller 2 is fixed to the motor shaft 11 of the forward / reverse rotation motor 1 with blades 22 spirally protrudingly provided on the outer periphery of a shaft portion 21 formed in a substantially conical shape. The end outer diameter ratio φD / φd of the screw impeller 2 is set small so as to suppress the performance deterioration of the reverse rotation reverse flow while ensuring the performance of the forward rotation normal flow.

The pump casing 3 is provided with a cone-shaped body portion 33 substantially along the outer shape of the screw impeller 2 between the end plates 31 and 32 at both ends, and both end plates 31 and 32 cover both ends of the screw impeller 2. The body 33 is assembled so as to cover the outer circumference of the screw impeller 2.

Further, in the pump casing 3, fluid inlets / outlets 34, 35 are formed at both ends of the body portion 33 at both end portions of the screw impeller 2, and the inlets / outlets 34, 35 are connected to the inlet / outlet 3
It is opened tangentially to the rotation direction of the screw impeller 2 so that the normal rotation normal flow and the reverse rotation reverse flow can be obtained without collision of the flows from 4,35.

Further, on the side of the small outer diameter end of the screw impeller 2 which is the inlet side during forward rotation and forward flow and the outlet side during reverse rotation and reverse flow, a chamber for converting kinetic energy of fluid into pressure energy is provided.
36 are formed.

Next, the notches 4 and 5 are for receiving the recirculation of the fluid flowing in from the inlets / outlets 34 and 35 in the chamber 36, and are provided at the recirculation end when the inlets / outlets 34 and 35 are the recirculation start portions. The notches 4 and 5 are arranged so as to be positioned on the inner peripheral surface of the body portion 33, and inclined surfaces 41 and 51 for changing the received circulation to the axial flow of the screw impeller 2 are changed. It is formed as a facing surface.

Next, the operation of this embodiment will be described.

When the forward / reverse rotation motor 1 is normally rotated to normally rotate the screw impeller 2 (in the direction of arrow M), the fluid is sucked into the pump casing 3 from one inlet / outlet 34 as an inlet, and this fluid is supplied to the screw impeller. The other entrance / exit while receiving the feeding action in the axial direction (direction of arrow m) by the rotation of 2
35 is used as a discharge port and is discharged from here.

Conversely, when the forward / reverse rotation motor 1 is reversely rotated to reversely rotate the screw impeller 2 (in the direction of arrow N), the other inlet / outlet port 35 is used as an inlet port from which the fluid is sucked into the pump casing 3, and this fluid is transferred to the screw While being fed by the rotation of the impeller 2 in the axial direction (the direction of arrow n), one of the inlet / outlet ports 34 is used as a discharge port for discharging.

In this way, a forward flow and a reverse flow are obtained by the forward / reverse rotation of the forward / reverse rotation motor 1. In this case, the inlet / outlet 3
The fluid sucked through the suction ports 4, 35 generates a circulating flow that rotates in the chamber 36 along the inner peripheral surface of the pump casing 3.

For example, as shown in FIG. 2 and FIG. 3, the notch 4 receives the recirculation of the fluid sucked from the one inlet / outlet 34 at the time of forward flow pumping,
The circulation does not slip through between the pitches of the screw impeller 2, so that there is no loss in the axial feed action of the screw impeller 2 with respect to the fluid, and the circulation received by the notch 4 is the inclined surface 41.
Diverted to axial flow by.

Further, since the notch 4 is located at the end of the circulation when the inlet / outlet 34 is the beginning of the circulation, the presence of the notch 4 does not hinder the suction of the fluid, and the suction can be performed smoothly. Since this smoothly flowing fluid is diverted in the axial direction by the inclined surface 41 with the same momentum, the momentum is also obtained in this axial flow.

If, as shown in FIG. 4, the notch 60 is arranged at the beginning of the recirculation, a shearing force is generated in the flow due to the collision of the fluid with the notch 60, causing a large suction loss due to the turbulence of the fluid. Therefore, in order to eliminate this point, it is the best measure to provide the notch 4 at the end of the circulation.

In addition, even when the reverse reverse flow occurs in which the other inlet / outlet port 35 serves as an inlet port, the notch 5 and the inclined surface 51 provide the same operation as described above.

As described above, at the time of normal rotation and normal flow, the fluid that circulates in the chamber 36 as described above almost disappears, and there is no loss in the axial feeding action of the screw impeller 2 with respect to the fluid, which improves the pump efficiency. The required pump flow rate is secured.

On the other hand, at the time of reverse rotation and reverse flow, the fluid flowing in from the inlet / outlet 35 as described above is sent only at the pitch of the screw impeller 2 due to the centrifugal force of the fluid, and the fluid is supplied by the chamber 36 provided on the outlet side. The kinetic energy applied to is converted into pressure energy and is discharged from the inlet / outlet 34 to secure the required lift.

As a result, the flow rate-head characteristic of the pump of the embodiment is as shown in FIG. 5, and it is possible to secure the required high flow forward rotation forward flow performance and the required high head reverse rotation backflow performance. Is also achieved.

Although the embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and the present invention can be applied even if there is a design change or the like within a range not departing from the gist of the present invention. included.

For example, the application point of the pump of the present invention is not limited to the boiling cooling system of the internal combustion engine described in the prior art, and high flow performance during forward rotation normal flow and high head performance during reverse rotation reverse flow are applicable. Of course, it can be applied to other systems as required.

(Effect of the Invention) As described above, in the screw centrifugal pump of the present invention, the screw impeller is single, and the end outer diameter ratio is small so as to suppress the deterioration of the reverse rotation reverse flow performance. The inlet and outlet should be opened tangentially to the direction of rotation of the screw impeller so that forward rotation normal flow and reverse rotation reverse flow can be obtained without the flow from the inlet and outlet colliding. When a chamber is formed on the small outer diameter end side of the screw impeller that is the side, and a notch for receiving the recirculation in the chamber that is the inlet side at the time of forward rotation normal flow, when the inlet and outlet are the recirculation start part It is arranged on the inner surface of the pump casing at the end of the recirculation, and the notch has a deflecting surface that diverts the recirculation to the axial flow of the screw impeller. It is possible to provide a forward / reverse pump that is strong and has a small decrease in flow rate at high water temperature, and that achieves both high flow rate characteristics during forward rotation forward flow and high head characteristics during reverse rotation reverse flow.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a screw centrifugal pump according to an embodiment of the present invention, FIGS. 2 to 4 are explanatory views of the operation of this embodiment, and FIG. 5 is a normal rotation forward flow and reverse rotation in the embodiment pump. Flow rate-lift characteristic diagram during rotational reverse flow, FIG. 6 is a characteristic diagram showing the required flow rate during forward rotation and required lift during reverse rotation, and FIG. 7 is a schematic diagram and flow rate in which two screw impellers are combined to form a drum shape. -Height characteristic diagram, FIG. 8 is a schematic diagram using a single screw impeller and flow rate-head characteristic diagram, FIG. 9 is a schematic diagram in which end outer diameter ratio is tuned and flow rate-head characteristic diagram, FIG. Fig. 11 is a schematic diagram of a pump in which a water flow collides with the tip of an impeller and a flow rate-lift characteristic diagram, and Fig. 11 is a schematic diagram of a pump in which a water flow does not collide with the tip of an impeller and a flow rate-lift characteristic diagram.
Figure 12 is a schematic diagram of the pump that forms the chamber and the flow rate.
It is a lift characteristic diagram. A ... Screw centrifugal pump 1 ... Forward / reverse motor 2 ... Screw impeller 3 ... Pump casing 4,5 ... Notches 41,51 ... Inclined surface (direction of change) 34, 35 ... Inlet / outlet 36 ... Chamber

Claims (1)

[Scope of utility model registration request] 1. A forward / reverse rotation motor, a screw impeller attached to the forward / reverse rotation motor, a pump casing which covers an outer periphery and both ends of the screw impeller, and has a fluid inlet / outlet formed at both end portions of the screw impeller,
In the screw centrifugal pump provided with, the screw impeller is a single, the end outer diameter ratio,
It is set small so as to suppress the deterioration of the reverse rotation reverse flow performance, and the inlet and outlet are set in the rotational direction of the screw impeller so that the forward rotation forward flow and the reverse rotation reverse flow can be obtained without the flow from the inlet and outlet colliding. A notch for opening in the tangential direction, forming a chamber on the small outer diameter end side of the screw impeller that is the outlet side when reverse rotation reverse flow, and for receiving the recirculation in the chamber that is the inlet side when forward rotation normal flow Is disposed on the inner surface of the pump casing at the recirculation end position when the inlet / outlet is the recirculation start portion, and the notch has a deflection surface that diverts the circulation flow to the axial flow of the screw impeller. A screw centrifugal pump characterized by being formed.