阅读说明：本技术 自吸式离心泵 (Self-priming centrifugal pump ) 是由 卢卡·尼科林 于 2019-07-18 设计创作，主要内容包括：自吸式离心泵包括：泵本体(10),该泵本体具有内部腔(11),该内部腔具有在使用构型中布置在水平位置中的纵向轴线(A),该纵向轴线将所述内部腔(11)分配到上部区域(S)和下部区域(I)中；抽吸开口(12),该抽吸开口形成在所述泵本体(10)的前部表面(13)上并形成在所述上部区域(S)处；泵送室(20),该泵送室与所述泵本体(10)相关联,并具有位于所述泵本体的前部部分处的轴向入口开口(21)；叶轮组(22),该叶轮组布置在所述泵送室(20)内侧；喷射器组(30),该喷射器组延伸到泵本体(10)的所述内部腔(11)中,并且包括喷射喷嘴(31)和定形状成发散轮廓的抽吸导管(32),该抽吸导管在该抽吸导管的较宽的部段处连接至泵送室(20)的入口开口(21)；辅助抽吸导管(34),该辅助抽吸导管布置在泵本体(10)的所述内部腔(11)内侧并且位于上部区域(S)处,并且该辅助抽吸导管适于将所述抽吸开口(12)与泵送室(20)的所述入口开口(21)直接连通。(The self-priming centrifugal pump comprises: a pump body (10) having an internal cavity (11) with a longitudinal axis (A) arranged in a horizontal position in a configuration of use, which longitudinal axis distributes said internal cavity (11) into an upper region (S) and a lower region (I); a suction opening (12) formed on a front surface (13) of the pump body (10) and at the upper region (S); a pumping chamber (20) associated with said pump body (10) and having an axial inlet opening (21) at a front portion of said pump body; an impeller group (22) arranged inside the pumping chamber (20); an ejector group (30) extending into said internal cavity (11) of the pump body (10) and comprising an ejection nozzle (31) and a suction duct (32) shaped with a diverging profile, connected at its wider section to the inlet opening (21) of the pumping chamber (20); -an auxiliary suction duct (34) arranged inside said internal cavity (11) of the pump body (10) and at the upper region (S) and adapted to communicate said suction opening (12) directly with said inlet opening (21) of the pumping chamber (20).)

1. A self-priming centrifugal pump comprising:

a pump body (10) provided with an internal cavity (11) having a longitudinal axis (A) arranged in use in a horizontal position, said axis defining said internal cavity (11) into an upper region (S) and a lower region (I);

a suction opening (12) formed on a front surface (13) of the pump body (10) and at the upper region (S) above the longitudinal axis (A);

an outlet opening (14) formed on an upper surface (15) of the pump body (10);

a pumping chamber (20) associated with the pump body (10) and having an axial inlet opening (21) at a front portion thereof;

an impeller group (22) arranged into the pumping chamber (20) and provided with an axial hub (23) configured to be associated with a motor shaft (24) coaxial thereto according to the longitudinal axis (A);

an ejector group (30) located in the internal cavity (11) of the pump body (10) and axially associated with the pumping chamber (20), the ejector group (30) comprising an ejection nozzle (31) and a collection suction duct (32) shaped with a diverging profile connected to the inlet opening (21) of the pumping chamber (20) at the end of its wider section,

a feed conduit (33) configured for connecting the suction opening (12) with the collection suction conduit (32) at the injection nozzle (31),

an auxiliary suction duct (34) arranged into the internal cavity (11) of the pump body (10) and at the upper region (S) above the horizontal axis (A) and configured for directly connecting the suction opening (12) with the inlet opening (21) of the pumping chamber (20),

characterized in that it comprises a non-return valve (35) arranged inside the auxiliary suction duct (34), said non-return valve (35) being intended to block the auxiliary suction duct (34) when the pressure at the region of the collection suction duct (32) close to the mouth of the inlet opening of the pumping chamber (20) is greater than the pressure at the upper portion of the auxiliary suction duct (34).

2. A centrifugal pump according to claim 1, wherein the auxiliary suction duct (34) has a substantially rectilinear shape.

3. A centrifugal pump according to claim 2, wherein the auxiliary suction duct (34) is inclined according to the angle of the determined width with respect to the longitudinal axis (a).

4. A centrifugal pump according to any one of the preceding claims, wherein the feed duct (33) is guided in a substantially radial direction with respect to the collecting suction duct (32) at the upper region (S) of the pump body (10), and the feed duct (33) is connected at an upper portion with the suction opening (12).

5. A centrifugal pump according to any one of the preceding claims, wherein at high flow rates the pressure at the region of the collecting suction duct (32) close to the mouth of the inlet opening (21) of the pumping chamber (20) is lower than the pressure at the upper portion of the auxiliary suction duct (34), so that the non-return valve (35) opens the auxiliary suction duct (34).

6. A centrifugal pump according to any one of the preceding claims, wherein at low flow rates, the pressure at the region of the collecting suction duct (32) close to the mouth of the inlet opening (21) of the pumping chamber (20) is higher than the pressure at the upper portion of the auxiliary suction duct (34), so that the non-return valve (35) blocks the auxiliary suction duct (34).

Technical Field

The invention relates to a self-priming centrifugal pump.

Background

It is known to use self-priming centrifugal pumps provided with an ejector group connected on one side with the suction of the liquid and on the opposite side with the inlet of an impeller group coaxial with respect to the ejector group.

More specifically, a self-priming centrifugal pump is known which comprises a generally cylindrical body having a forwardly facing liquid suction opening and an outlet opening on an upper side. Inside the pumping chamber associated with the pump body there is housed a set of impellers suitable for being rotated by suitable motor means, generally of the electric type.

The ejector set is disposed inside a cavity defined by the pump body. The ejector group comprises an ejection nozzle and a collecting suction duct forming a diverging profile. The collecting suction duct is connected on one side with the suction opening and on the opposite side with the inlet of the group of impellers which is coaxial with respect to the collecting suction duct. The recirculation of the liquid is performed by means of a spray nozzle; the liquid fills the internal cavity of the pump body after exiting from the pumping chamber of the impeller set.

In use, the total flow through the impeller set is partially conveyed through the outlet opening and partially recirculated through the injection nozzle due to the venturi effect created in the collecting suction duct.

Patent EP 0.401.670, for example, shows a self-priming centrifugal pump of this type.

A major problem with the use of centrifugal pumps of the aforementioned type is the performance decay that occurs when a particular flow rate value is reached. This effect is due to the incipient cavitation generated in the region around the injection nozzle at the opening of the venturi tube. It follows that the limitation of the maximum flow rate that can be obtained in centrifugal pumps of the aforementioned type is caused by the aforementioned performance decay.

Fig. 2 and 3 show in diagrammatic form by broken lines H and P the variation of the hydraulic head and the percentage efficiency in relation to the flow rate of a known self-priming centrifugal pump, respectively. It is clearly visible that both the head and the efficiency of the pump decrease when the predetermined flow rate value Q' is reached. Finally, the value Q' represents the maximum flow rate that can be achieved by a centrifugal pump of the type described above.

Us patent 2,634,680 shows a self-priming centrifugal pump that can be selectively operated in a first mode (so-called shallow well system) and a second mode (so-called deep well system). The pump is provided with a bypass conduit through which liquid can flow from the outlet opening to the impeller assembly without engaging the injector assembly.

GB 397,035 discloses another embodiment of a self-priming centrifugal pump fitted with a bypass conduit.

However, these solutions do not dispense with improvements.

Disclosure of Invention

The object of the present invention is to solve the above problems by designing a self-priming centrifugal pump which allows to increase the maximum achievable flow rate while maintaining a high level of performance.

Within this aim, a further object of the invention is to provide a self-priming centrifugal pump which ensures that the maximum pressure is maintained.

Another object of the present invention is to provide a self-priming centrifugal pump which allows to improve the efficiency of the pumping group.

A further object of the present invention is to provide a self-priming centrifugal pump of simple construction and functional concept, versatile use, and relatively economical cost, which is provided with a certain reliable operation.

According to the invention, the above object is achieved by a self-priming centrifugal pump according to claim 1.

The self-priming centrifugal pump comprises: a pump body having an internal cavity with a longitudinal axis arranged in a horizontal position in a configuration of use; a pumping chamber associated with the pump body and having an axial inlet opening at a front portion of the pump body; an ejector group extending inside said internal cavity of the pump body according to said longitudinal axis and axially associated with said pumping chamber, within said internal cavity of the pump body an upper zone and a lower zone being defined with respect to said ejector group; a suction opening formed on a front surface at the upper region of the pump body, the upper region being located above the ejector group; an auxiliary suction duct arranged inside said internal cavity of the pump body and at said upper region with respect to said ejector group, and configured for directly connecting said suction opening with said inlet opening of the pumping chamber.

Inside said pumping chamber there is arranged a set of impellers provided with an axial hub adapted to be associated with a motor shaft coaxial with the axial hub according to said longitudinal axis.

The ejector group comprises an ejection nozzle and a collecting suction duct shaped in a diverging profile, connected to the inlet opening of the pumping chamber at the end of its wider section.

Preferably, said diverging profile is composed of a first portion with constant inclination and a second portion with increasing inclination, which engages in said axial inlet opening of the pumping chamber.

Preferably, the auxiliary suction duct opens into the upper part of the first portion with a constant inclination of the collecting suction duct.

Advantageously, the pump comprises a non-return valve arranged inside said auxiliary suction duct.

Advantageously, the auxiliary suction duct has a substantially rectilinear arrangement.

Preferably, said auxiliary suction duct is inclined at an angle of predetermined width with respect to said longitudinal axis of the pump body.

Preferably, the angle of the predetermined width is about 45 °.

Preferably, the auxiliary suction duct has a slightly curved upper portion which can be inserted into the top of the feed duct in front of the suction opening.

Preferably, said upper portion of the auxiliary suction duct is engaged at the top of said feed duct according to an axis substantially parallel to the horizontal axis of said suction opening.

Advantageously, said collection suction duct is connected at said ejection nozzle to a feed duct extending substantially in a radial direction at said upper region of the pump body and connected at the top to said suction opening.

Preferably, the feed duct opens into a portion of the collecting suction duct arranged in an annular shape around the spray nozzle.

Advantageously, at high flow rates, the pressure at the region of the collecting suction duct near the mouth of the inlet opening of the pumping chamber is lower than the pressure at the top of the auxiliary suction duct.

In this way, the check valve opens the auxiliary suction duct, allowing the pump to achieve high flow rates and high efficiency.

Advantageously, at low flow rates, the pressure at the region of the collecting suction duct near the mouth of the inlet opening of the pumping chamber is higher than the pressure at the top of the auxiliary suction duct.

In this way, the check valve closes the auxiliary suction duct, allowing the pump to maintain a high head.

Drawings

The details of the invention will become more apparent from the detailed description of a preferred embodiment of a self-priming centrifugal pump according to the invention, which is illustrated by way of non-limiting example only in the accompanying drawings, in which:

FIG. 1 shows an axial cross-sectional view of a self-priming centrifugal pump;

figures 2 and 3 show graphs of pump head and efficiency, respectively, as a function of flow rate.

Detailed Description

With particular reference to these figures, reference numeral 1 indicates a self-priming centrifugal pump according to the invention. The centrifugal pump 1 comprises a pump body 10 shaped with an internal cavity 11. The pump body 10 defines a housing for the operating components of the pump.

The pump body 10 has, for example, a substantially cylindrical shape, and has a longitudinal axis a arranged in a horizontal position in the configuration of use. As described below, the longitudinal axis a represents the motor axis of the rotating part of the pump.

The longitudinal axis a distributes the internal cavity 11 of the pump body 10 into the upper region S and the lower region I.

A suction opening 12 is formed on a front surface 13 of the pump body 10. The suction opening 12 is arranged at an upper region S of the pump body 10 above the longitudinal axis a.

An outlet opening 14 is formed on an upper surface 15 of the pump body 10. The outlet opening 14 communicates with an upper region S of the internal cavity 11 of the pump body 10. The outlet opening 14 is arranged radially with respect to the longitudinal axis a of the pump body 10.

The pumping chamber 20 is associated with the pump body 10. The pumping chamber 20 has an axial inlet opening 21 at its front portion facing the internal cavity 11 of the pump body 10. The pumping chamber 20 generally encloses the internal cavity 11 of the pump body 10 on the opposite side of the front surface 13.

Inside the pumping chamber 20 there is arranged a set of impellers 22 of known shape; the impeller assembly 22 is provided with an axial hub 23 axially associated with a motor shaft 24 coaxial therewith. The motor shaft 24 is adapted to be rotated by a motor member 25, for example of the electric type, only partially represented in the figures.

The ejector group 30 is axially associated with the pumping chamber 20 and extends inside the internal cavity 11 of the pump body 10. The ejector group 30 comprises an ejection nozzle 31 and a collecting suction duct 32 shaped in a diverging profile. The collection suction duct 32 is connected at the end of its wider section to the mouth of the inlet opening 21 of the pumping chamber 20; at the opposite end, the collecting suction duct 32 is connected to a feed duct 33, which extends substantially in a radial direction at the upper region S of the pump body 10 and is connected at the top to the suction opening 12.

Preferably, the feeding duct 33 opens into a portion of the collecting suction duct 32 arranged in an annular shape around the ejection nozzle 31.

In the embodiment shown, the injector group 30 is made up of a rear section 30a and a front section 30 b. The rear portion 30a is generally shaped with a collection suction duct 32 and a feed duct 33; the front portion 30b is constituted by a cover which closes the rear portion 30a at the front and is shaped with the injection nozzle 31, and by a sleeve 36 which is tightly inserted in the suction opening 12.

According to the invention, the self-priming centrifugal pump has an auxiliary suction duct 34 adapted to put the suction opening 12 in direct communication with the inlet opening 21 of the pumping chamber 20. The auxiliary suction duct 34 has a substantially rectilinear arrangement and is housed at said upper region S of the internal cavity 11 of the pump body 10, above the longitudinal axis a. In particular, the auxiliary suction duct 34 is inclined at an angle of predetermined width with respect to the longitudinal axis a; this angle is included in the range of, for example, about 45 deg. depending on the size of the pump.

In practice, the secondary suction duct 34 has a slightly curved portion at the top of the same, which is inserted into the top of the feed duct 33 in front of the suction opening 12. Preferably, the upper portion of the secondary suction duct 34 is engaged in the top of the feed duct 33 by an axis of its upper portion substantially parallel to the horizontal axis of the suction opening 12.

The check valve 35 is arranged inside the auxiliary suction duct 34 in a substantially central position. The non-return valve 35 is adapted to close the auxiliary suction duct 34 when the pressure at the region of the collecting suction duct 32 close to the mouth of the inlet opening 21 of the pumping chamber 20 is higher than the pressure at the top of the auxiliary suction duct 34.

The operation of the self-priming centrifugal pump can be readily understood from the above description.

In use, the total flow through the impeller set 22 is introduced into the internal cavity 11 of the pump body 10. This total flow is conveyed partly through the outlet opening 14 and partly drawn back into the circulation through the injection nozzle due to the venturi effect created in the collecting suction duct 32.

When the required flow rate exceeds a predetermined value, the check valve 35 will open the auxiliary suction conduit 34 and allow the liquid to pass directly from the suction opening 12 to the inlet of the pumping chamber 20. In this way, cavitation in the area surrounding the spray nozzle at the entrance of the collecting suction duct 32 is avoided, while allowing the total flow rate into the impeller assembly 22 to be increased up to the desired value.

In particular, when operating at high flow rates, the pressure at the region of the collecting suction duct 32 close to the mouth of the inlet opening 21 of the pumping chamber 20 is lower than the pressure at the top of the auxiliary suction duct and, therefore, the check valve 35 opens the auxiliary suction duct 34. In this way, greater flow rates and greater efficiency are achieved compared to conventional self-priming pumps.

In contrast, when operating at a low flow rate, the pressure at the region of the collecting suction duct 32 close to the mouth of the inlet opening 21 of the pumping chamber 20 is higher than the pressure at the top of the auxiliary suction duct 34, and therefore the check valve 35 closes the auxiliary suction duct 34. In this way, greater prevalence is achieved compared to conventional centrifugal pumps.

In fact, it has been found that the self-priming centrifugal pump according to the invention has the following trends of head and efficiency: this trend remains at a relatively high value for a significantly higher flow rate than a conventional pump, as shown in the graphs of fig. 2 and 3, compared to the head and the percentage efficiency of a conventional pump, represented by the dashed lines H and P, which indicate the variations of the head and the percentage efficiency of the pump in question, respectively, as a function of the flow rate. It should be noted that the head and efficiency of the pump according to the invention remain satisfactory values even when the value of Q' representing the maximum flow rate that can be achieved in a centrifugal pump of conventional type is exceeded.

The self-priming centrifugal pump according to the invention therefore achieves the object of increasing the maximum flow rate achievable while maintaining a high level of performance.

The self-priming centrifugal pump described by way of example can be varied according to different requirements.

In practical embodiments of the invention, the materials used, as well as the shapes and dimensions, may vary according to requirements.

Where technical features mentioned in any claim follow reference signs, such reference signs are strictly included for the purpose of enhancing the understanding of the claims, and therefore the reference signs shall not in any way be construed as limiting the scope of each element identified by way of example by such reference signs.