EP2609336B1

EP2609336B1 - Submersible pump

Info

Publication number: EP2609336B1
Application number: EP10745286.4A
Authority: EP
Inventors: Ram Krishna Agrawal
Original assignee: Husqvarna AB
Current assignee: Husqvarna AB
Priority date: 2010-08-26
Filing date: 2010-08-26
Publication date: 2016-08-17
Anticipated expiration: 2030-08-26
Also published as: EP2609336A1; WO2012025154A1

Description

TECHNICAL FIELD

The present invention relates to a submersible pump. In particular, the present invention relates to a submersible pump powered by an electric motor as defined in the preamble of claim 1.

BACKGROUND

Submersible pumps are well known in the art. Submersible pumps are utilized in a variety of applications, such as, but not limited to, irrigation, aquariums, drainage, sewage, oil and water wells, residential supply, or the like. Typically, such pumps include a non-return valve and a pressure switch. The non-return valve ensures a unidirectional flow of a working fluid from an inlet to the outlet. The pressure switch shuts down the pump in case a pressure of the working fluid exceeds a predetermined threshold.
Typically, the non-return valve and the pressure switch are arranged as completely separate units in separate housings. Such an arrangement may not be compact and reduce portability of the pump. Alternatively, at least some components of the non-return valve and the pressure switch are common. For example, DE Pat. No. 3,344,765 A1 published on May 13, 1985 and assigned to VDO SCHINDLING, titled "Submerged pump" discloses a submersible pump with a plastic part that performs multiple functions. The plastic part acts as a sealing member, a pressure diaphragm and a valve flap of a non-return valve. The pressure diaphragm is coupled to a pressure switch whereas the valve flap is provided in a passage for the working fluid. However, if the plastic member sustains any damage or fails during operation of the pump, the pressure switch and the non-return valve becomes simultaneously non-functional. This may cause serious damage to various components of the pump including, but not limited to, the motor. Further, leakage of the working fluid may also be detrimental to various components.
US Pat. 2005/0095150 A1 published on May 5, 2005 discloses a centrifugal multistage pump having a motor, a first circuit board inverter and a pressure transducer. The arrangement of the first circuit board inverter and the pressure transducer within the pump body may not be compact.
In light of the foregoing, there is a need for a submersible pump with a compact and robust design.

SUMMARY

In view of the above, it is an objective of the present invention to solve or at least reduce the problems discussed above. In particular, the objective is to provide an improved submersible pump, with a compact and robust design.
The objective is at least partially achieved according to a novel submersible pump described in claim 1. The submersible pump powered by an electric motor includes at least one inlet, at least one outlet, and at least one passage between the inlet and the outlet. A non-return valve is provided in the passage to ensure a unidirectional flow of a working fluid from the inlet to the outlet. Further, a pressure switch is provided to monitor a pressure within the passage. Additionally, a printed circuit board (PCB) assembly is provided, the PCB assembly including a PCB housing and a PCB. The non-return valve, the pressure switch and the PCB assembly are arranged such that an overlap is provided between at least two of the non-return valve, the pressure switch, and the PCB assembly in a horizontal plane. Such an arrangement of the non-return valve, the pressure switch and the PCB assembly results in a compact configuration of the pump. This may improve portability, installation and storage of the pump. Further, a compact configuration may lead to lower material and manufacturing costs. The pump may also become more efficient with lower leakage and/or energy losses.
Further the pressure switch may be located substantially below the PCB assembly in a vertical direction.
According to claim 2, the non-return valve includes a valve body, a valve guide supporting the valve body, and a first spring, the first spring normally biasing the valve body in a closed position.
According to claim 3, the submersible pump includes a flow sensor to detect a flow of a working fluid. Further, according to claim 4, the flow sensor includes a magnet, and at least one hall sensor which outputs a first electric signal. Additionally, according to claim 5, the hall sensor is provided on the PCB. According to claim 6, the magnet is configured to move with the valve body.
According to claim 7, the pressure switch includes a second spring, a membrane havinng a first surface and a second surface, a piston normally biased against the first surface of the membrane with a predetermined force by the second spring, and an adjusting screw which regulates the predetermined force. Further, according to claim 8, an opening is provided to transmit a pressure within the passage to the second surface of the membrane. Moreover, according to claim 9, at least one electromechanical transducer detects a movement of the membrane, the electromechanical transducer outputting a second electric signal.
According to claim 10, the PCB includes a logic circuit which at least accepts the first electric signal and the second electric signal, and generates an output signal to control the motor.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will in the following be described in more detail with reference to the enclosed drawings, wherein:

FIG. 1 illustrates a sectional view of a submersible pump, according to an embodiment of the present invention;
FIG. 2 illustrates a top view of the submersible pump taken along the A-A axis, according to an embodiment of the present invention; and
FIG. 3 illustrates a sectional view of the submersible pump with a magnet located in a casing, according to an embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which example embodiments of the invention incorporating one or more aspects of the present invention are shown. This invention may, however, be embodied in many different forms if within the scope of the appended claims. In the drawings, like numbers refer to like elements.
FIG. 1 illustrates a sectional view of a submersible pump 100, according to an embodiment of the present invention. The submersible pump 100 (hereinafter referred to as the "pump 100") may be used to pump any working fluid, for example, water, oil, sewage, slurry, or the like. Moreover, the pump 100 may be used in various applications, such as, irrigation, aquariums, oil or water wells, drainage, sewage, residential supply etc. In addition, any suitable size, shape or type of elements or materials could be used. Further, as used herein, the terms "horizontal direction" and "vertical direction" indicate a direction relative to the pump 100. The terms "horizontal plane" and "vertical plane" are planes parallel to the horizontal direction and the vertical direction respectively. Moreover, the terms "left" and "right" of any component or portion may in general refer to left and right sides of the component or portion in the horizontal direction. Similarly, the terms "above" and "below" of any component or portion may in general refer to sides above and below of the component or portion in the vertical direction. It may be apparent to a person ordinarily skilled in the art that the terms "left", "right", "above" and "below" are with respect to a particular orientation of the pump 100, and changes when viewed from other orientations. Further, the term "electric signal", unless otherwise mentioned, may refer to any analogue or digital signal. Additionally, any extent of overlap, between two or more components of the pump 100, expressed as a percentage may be calculated based on a distance between the components with the overlap and a distance between the components without any overlap. The distance between the components may be a distance between central points, perpendicular distance, or the like.
As illustrated in FIG. 1 , the pump 100 includes an inlet 102 and an outlet 104 with a passage 106 connecting the inlet 102 and the outlet 104. However, the pump 100 may include two or more inlets, outlets, and/or passages without departing from the essence of the present invention. Alternatively, the passage 106 may have multiple branches to connect the two or more inlets and/or outlets. The inlet 102 and/or outlet 104 may also have connecting portions (not shown) (For example, threads) to connect with any external pipes or supply. As illustrated in FIG. 1, the pump 100 includes a main housing 108 which encloses at least some components of the pump 100. Alternatively, the pump 100 may be of a modular construction with two or more housings attached to each other. A cover 109 is provided to cover an upper portion if the main housing 108. Further, the pump 100 also includes an adapter 110 attached to the main housing 108 for connecting an electric motor (hereinafter referred to as "the motor") and impeller assembly (not shown) to the pump 100. A power cable (not shown) is provided to provide electrical energy to the motor. The motor is controlled by a printed circuit board (hereinafter referred to as "the PCB") (shown in FIG. 2). The motor drives the impeller to pump the working fluid through the inlet 102 into the passage 106.
As illustrated in FIG. 1, the pump 100 includes a non-return valve 112 provided in the passage 106 to divide the passage 106 into a first portion 114 and a second portion 116. The non-return valve 112 includes a valve body 118, a first spring 120 and a valve guide 122. Further, the valve body 118 includes a valve cone 124 and a valve stem 126. One end of the first spring 120 rests against the valve cone 124 of the valve body 118, whereas the other end of the first spring 120 rests against the valve guide 122. Further, the valve guide 122 restricts a movement of the valve stem 126 substantially parallel to the vertical direction V. The first spring 120 normally biases the valve cone 124 with a first O-ring 127 against a conical surface of the main housing 108 to retain the non-return valve 112 in a closed position. Thus, in a closed position of the non-return valve 112, a flow of the working fluid to and/or from the second portion 116 to the first portion 114 of the passage 106 is substantially precluded. In an embodiment of the present invention, a lip seal 125 is also provided to limit the flow of the working fluid by allowing the working fluid to flow through a small groove passage in the main housing 108 in a lower flow rate range.
During operation of the pump 100, the non-return valve 112 permits a unidirectional flow of the working fluid from the first portion 114 to the second portion 116 only when a pressure of the working fluid overcomes a spring force of the first spring 120, and lifts the valve cone 124 with the first O-ring 127 from a closed position. The spring force of the first spring 120 may be predetermined to permit a flow of the working fluid only above a threshold pressure. Thus, the non-return valve 112 prevents a backflow of the working fluid from the second portion 116 to the first portion 114. This may prevent any damage to various components of the pump 100, such as, the motor, the impeller, or the like. It may be apparent to a person ordinarily skilled in the art that the non-return valve 112 illustrated in FIG. 1 may be of any other shape or configuration within the scope of the present invention. For example, instead of the first spring 120, any other resilient member may be used. Moreover, alternate sealing means (For example, a labyrinth seal) may be utilized in place of the lip seal 125 and the first O-ring 127.
In an embodiment of the present invention, a magnet (shown in FIGS. 2 and 3) is provided to move with the valve body 118. Further, a hall sensor is provided on the PCB to output a first electric signal (hereinafter referred to as "the first signal) in response to a movement of the magnet (described in detail in conjunction with FIG. 2 ).
As illustrated in FIG. 1 , the pump 100 includes a pressure switch 128 to monitor a pressure of the working fluid in the passage 106. The pressure switch 128 includes a membrane 130, a second spring 132, a piston 134 and an adjusting screw 136. The second spring 132 normally biases the piston 134 against a first surface 138 of the membrane 130 with a predetermined force. The adjusting screw 136 regulates the predetermined force with which the piston 134 is biased against the first surface 138 of the membrane 130. As illustrated in FIG. 1, the membrane 130, the second spring 132, the piston 134 and the adjusting screw 136 are substantially enclosed within a pressure switch cover 140. The pressure switch cover 140 may include an aperture (not shown) to enable a tool to be inserted inside the pressure switch cover 140 for adjustment of the adjusting screw 136. A pressure switch connector 142 is provided to connect the pressure switch 128 to the pump 100. The pressure switch connector 142 may be a separate component or integral with the pressure switch 128. A second O-ring 144 is provided to substantially prevent leakage into or out of the pressure switch connector 142. Further, the pressure switch connector 142 includes an opening 146 to connect the second portion 116 of the passage 106 with a space 148 above a second surface 150 of the membrane 130. However, the opening 146 may connect any other portion of the passage 106 with the space 148 within the scope of the present invention. Thus, the piston 134 exerts the predetermined force on the first surface 138 of the membrane 130, whereas a pressure of the working fluid in the second portion 116 of the passage 106 is transmitted to the second surface 150 of the membrane 130. When a pressure on the second surface 150 exceeds the predetermined force on the first surface 138, the membrane 130 is displaced downwards from a normal position.
In an embodiment of the present invention, an electromechanical transducer (not shown) is provided to output a second electric signal (hereinafter referred to as ("the second signal"). The electromechanical transducer may be part of the pressure switch 128 or a separate component. The electromechanical transducer is electrically connected to the PCB such that the first signal is transmitted to the PCB. The electromechanical transducer may be a micro switch, a relay, a piezoelectric transducer, proximity sensor, or a combination of any of these. In an embodiment of the present invention, the PCB includes a logic circuit (not shown) which controls operation of the pump based at least on the first and second signals (explained in detail in subsequent paragraphs). It may be apparent to a person ordinarily skilled in the art that the pressure switch may be of any other shape or configuration if without departing from the scope of the present invention as claimed. For example, the second spring 132 may be replaced by any other resilient member. Further, the predetermined force on the membrane 130 may be adjusted by other means (For example, electromechanical, hydraulic) instead of the adjusting screw 136.
FIG. 2 illustrates a top view of the pump 100 along a horizontal plane A-A. As illustrated in FIG. 2 , the pump 100 includes the non-return valve 112, the pressure switch 128 and a PCB assembly 202. The non-return valve 112 and the pressure switch connector 142 are arranged in a secondary housing 204. Consequently, an overlap exists between the non-return valve 112 and the pressure switch 128. In an embodiment of the present invention, the extent of overlap between the non-return valve 112 and the pressure switch 128 lies between a range of about 5% to 25%. Further, the extent of the overlap is such that a distance D1 between central points 206 and 208 of the non-return valve 112 and the pressure switch 128 respectively lies substantially between a range of about 25 mm to 40 mm. In an embodiment of the present invention, the overlap between non-return valve 112 and the pressure switch connector 142 lies substantially between a range of about 5% to 15%. Further, the extent of overlap is such that a distance D2 between the central point 206 of the non-return valve 112 and a central point 210 of the pressure switch connector 142 lies substantially between a range of about 20 mm to 30 mm. The secondary housing 204 may be integral with the main housing 108 or may be a separate component which is attached to the main housing 108.
As shown in FIG. 2 , the PCB assembly 202 includes a PCB housing 212 and the PCB 214. The PCB housing 212 may retain the PCB 214 in a fixed position and/or safeguard the PCB 214 and various electric components of the PCB 214 from any leakage, external particulate matter, vibrations, extreme temperatures and humidity, or the like. The PCB housing 212 is arranged between a curvilinear portion 216 of the secondary housing 204, and the main housing 108 in the horizontal direction such that an overlap exits between the PCB assembly 202 and the pressure switch 128. In an embodiment of the present invention, the extent of overlap between the pressure switch 128 and the PCB 214 lies substantially between a range of about 10% to 20%. Further, the extent of the overlap is such that a perpendicular distance D3 between the central point 208 of the pressure switch 128 and the PCB 214 lies substantially between a range of about 20 mm to 30 mm. Further, the curvilinear portion 216 of the secondary housing 204 results in an overlap between the non-return valve 112 and the PCB 214. In an embodiment of the present invention, the extent of overlap between the non-return valve 112 and the PCB 214 lies between a range of about 5% and 15%. Consequently, the curvilinear portion 216 of the secondary housing 204 reduces a perpendicular distance D4 between the central point 206 of the non-return valve 112 and the PCB 214. The distance D4 lies substantially between a range of about 20 mm to 30 mm. The overlap percentages and the distances mentioned above are purely exemplary in nature, and the present invention may be envisioned with any other overlap percentages and distances. For example, the distances D1-D4, may proportionately change with a change in a scale of the pump 100.
It may be apparent to a person ordinarily skilled in the art that the arrangement of the non-return valve 112, the pressure switch 128 and the PCB assembly 202 results in a compact configuration of the pump 100. This may improve portability, installation and storage of the pump 100. Further, a compact configuration may also lead to lower material and manufacturing costs. Additionally, the pump 100 may become more efficient with lower leakage and/or energy losses. Further, the arrangement is illustrated in the horizontal plane A-A, but it may be obvious that overlap exists in all horizontal planes between a range in the vertical direction V. The arrangement of the non-return valve 112, the pressure switch 128 and the PCB assembly 202 as illustrated in FIG. 2 are for illustrative purposes and any other arrangement with overlaps may be within the scope of the present invention. For example, a first overlap may be provided between the non-return valve 112 and the PCB assembly 202 in a horizontal plane, whereas a second overlap is provided between the non-return valve 112 and the pressure switch 128 in a second horizontal plane. Additionally, in such a case, the pressure switch 128 may be located substantially below the PCB assembly 202 in the vertical direction V.
As shown in FIG. 2 , a magnet 218 is configured to move with the valve body 118 (described in conjunction with FIG. 3). The magnet 218 may be a permanent magnet or an electromagnet without deviating from the essence of the present invention. Further, the PCB 214 includes the hall sensor 220 which outputs the first signal. The magnet 218 and the hall sensor 220 may together form at least part of a flow sensor. In an embodiment of the present invention, the PCB 214 includes a logic circuit (not shown) which is configured to receive the first signal from the hall sensor 220. The logic circuit further receives the second signal from the electromechanical transducer which detects a movement of the membrane 130 of the pressure switch 128. Subsequently, the logic circuit generates an output signal to control the motor of the pump 100. Additionally, the logic circuit may also monitor a current state of the motor in order to generate the output signal. The logic circuit may also control any other electric component of the pump 100 within the scope of the present invention. The logic circuit may include a microprocessor, a microcontroller, one or more relays, one or more multi-vibrators, or a combination of any of these. Further, the first signal and/or the second signal may be processed in any manner, such as, amplified, modified from an analogue state to a digital state, filtered, or the like, before being transmitted to the logic circuit.
When the pump 100 is started, the non-return valve 112 moves upwards due to the flow of the working fluid and the magnet 218 triggers the first signal as soon as the magnetic field of the magnet 218 comes in contact with the hall sensor 220 mounted on the PCB 214. The first signal remains active as long as the flow exists and the non-return valve 112 is in such a position that the hall sensor 220 is in the magnetic filed of the magnet 218. This means that the first signal is active starting from a minimum flow rate of, for example 10 liters/ h, up to a maximum flow rate of the pump when the non-return valve 112 is fully open.
During operation of the pump, there is also a build-up of pressure in the passage 106 up to the second portion 116. The pressure may depend at least partly on the flow rate of the working fluid. In an embodiment of the present invention, the value of the pressure may depend on the pump performance curve wherein the pressure is inversely proportional to the flow rate.
Further, depending on the type of the electromechanical transducer, the second signal will be generated. In an embodiment of the present invention, the electromechanical transducer is a micro switch. The micro switch is activated when the membrane 130 is displaced downwards from a normal position, due to the pressure of the working fluid reaching a maximum pressure. Both the first signal from the hall sensor 220 and the second signal from the micro switch are processed by the logic circuit and the motor is switched on or off accordingly. The first signal and the second signal may be of a fixed type (Yes/No) or the variable type. In case of the variable type, the values of the first signal and the second signal may be shown on a display, for example, a LCD.
In an embodiment of the present invention, the motor is controlled according to a control strategy as depicted in the following table:

First signal Second signal Motor

No Yes Off

Yes No On

Yes Yes On

No No On (Dry-run: Off)
According to the table, if the first signal is in the No state, and the second signal is in the Yes state, then there may be a blockage in the passage 106. Thus, the logic circuit switches off the motor or does not activate the motor. In case, the first signal is in the Yes state, and the second signal is in the No state, the motor is switched on or kept running to build up preasure. Similarly, in case, both the first and second signals are in the Yes state, the motor is switched on or kept running. If both the first and second signals are in the No state, the pump might be in the start-up condition and thus pressure and flow has to be generated. It also might be that the pressure generated previous to switching off the motor of the pump 100 has relieved and has to be built up again to allow for the flow of water when the blockage of passage 106 is removed. If with in this situation the motor is switched on but the second signal does not change from the No state to the Yes state during a certain period of time (maybe 10 seconds) this might indicate a possible dry-run condition of the pump 100, i.e., the pump 100 is running without any supply of the working fluid. In this case, the motor of the pump 100 preferably should be switched off to avoid damages to the motor or other components of the pump 100.
It may be apparent to a person ordinarily skilled in the art that the control strategy of the motor, as described above, is for descriptive purposes only, and any other control strategy may be envisioned within the scope of the present invention.
Fig. 3 illustrates a sectional view of the pump 100. As shown in FIG. 3 , the magnet 218 of the flow sensor is located within a casing 302. The casing 302 is integral with the valve body 118. Specifically, the casing 302 is integral with the valve cone 124. Thus, when the valve body 118 is displaced, the magnet 218 also moves. In various embodiments of the present invention, the magnet 218 may be attached to the casing 302 by adhesives, welding, brazing, or the like.
In the drawings and specification, there have been disclosed preferred embodiments and examples of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation, the scope of the invention being set forth in the following claims.

Claims

A submersible pump (100) incuding a main housing (108) and powered by an electric motor comprising:
at least one inlet (102), at least one outlet (104), and at least one passage (106) between the inlet (102) and the outlet (104);

a non-return valve (112) provided in the passage (106), including a valve body (118) that further includes a valve cone (124) and a valve stem (126);

a pressure switch (128) which monitors a pressure within the passage (106); and

a printed circuit board assembly (202) comprising a printed circuit board housing (212) and a printed circuit board (214), wherein the printed circuit board (214) controls at least the motor;

characterized in that,

the non-return valve (112) and the pressure switch (128) are arranged in a secondary housing (204)

and the printed circuit board housing (212) is arranged between a curvelinear portion (216) of the secondary housing (204) and the main housing (108) in a projection onto a first plane which is normal to the direction of movement of the valve stem (126),

an overlap is provided between the non-return valve (112), the pressure switch (128), and the printed circuit board assembly (202), whereby, an overlap exists between the the pressure switch (128) and the printed circuit board assembly (202),

and a second overlap exists between the non-return valve (112) and the printed circuit board assembly (202).
The submersible pump (100) of claim 1, wherein the non-return valve (112) comprises a valve body (118), a valve guide (122) supporting the valve body (118), and a first spring (120), the first spring (120) normally biasing the valve body (118) in a closed position.
The submersible pump (100) of claim 1, wherein submersible pump (100) further comprises a flow sensor to detect a flow of a working fluid.
The submersible pump (100) of claim 3, wherein the flow sensor comprises a magnet (218), and at least one hall sensor (220) which outputs a first electric signal.
The submersible pump (100) of claim 4, wherein the hall sensor (220) is provided on the printed circuit board (214).
The submersible pump (100) of claim 4, wherein the magnet (218) is configured to move with the valve body (118).
The submersible pump (100) of claim 1, wherein the pressure switch (128) comprises a second spring (132), a membrane (130) having a first surface (138) and a second surface (150), a piston (134) normally biased against the first surface (138) of the membrane (130) with a predetermined force by the second spring (132), and an adjusting screw (136) which regulates the predetermined force.
The submersible pump (100) of claim 10, wherein an opening (146) is provided to transmit a pressure within the passage (106) to the second surface (150) of the membrane (130).
The submersible pump (100) of claim 11, wherein at least one electromechanical transducer detects a movement of the membrane (130), and wherein the electromechanical transducer outputs a second electric signal.
The submersible pump (100) of claim 9, wherein the printed circuit board (214) comprises a logic circuit which at least accepts the first electric signal and the second electric signal, and generates an output signal to control the motor.