EP3967881B1 - Pump - Google Patents

Description

The invention relates to a pump for hygiene-sensitive applications and a method for operating a pump.

Pumps for hygiene-sensitive applications are already known. The pamphlet DE 10 2019 102 073 A1 discloses a gear pump in which a partial volume flow of the pumped fluid is diverted into a rotor chamber on the pressure side in order to flush it with the fluid.

A significant disadvantage of the known pump is that the flushing of the rotor space is insufficient and undefined.

The pamphlet EP 3 115 609 A1 discloses a self-cleaning pump in which the medium used to flush the rotor space is taken from the suction side of the pump, fed via a riser line in the area of the rotor’s axis of rotation to the upper side of the rotor and, after flowing around the rotor on the lower side of the rotor, is returned to the suction side of the pump to be pressurized by a main pump means and fed to the pressure side of the pump.

The pamphlet U.S. 3,986,797 A discloses a magnetic pump in which part of a magnetic coupling is traversed by a flushing medium.

Proceeding from this, it is the object of the invention to specify a pump that enables improved flushing of the rotor chamber while at the same time being highly efficient.

The object is solved by a pump having the features of independent patent claim 1 . A method of operating of a pump is the subject of the independent patent claim 13. Preferred embodiments are the subject of the dependent claims.

According to a first aspect, the invention relates to a pump for delivering a fluid, in particular a liquid. The pump includes a delivery channel through which a fluid can be delivered. The delivery channel has a pump inlet and a pump outlet. Between the pump inlet and the pump outlet is a Pumping device provided for pumping the fluid. The pumping device has a suction side and a pressure side. The pumping device comprises two rotating conveying elements that engage in one another and by means of which a fluid flow is generated.

In addition, a drive motor is provided, which is drivingly coupled to at least one conveying element in order to set it in rotation. The drive motor has a rotor and a stator. The rotor of the drive motor is provided in a rotor space that is fluidically sealed off from the environment.

The pump also has a scavenging duct system for scavenging the rotor chamber with the pumped fluid, the scavenging duct system comprising a rotor chamber inlet and a rotor chamber outlet. The scavenging channel system is designed in such a way that the entire fluid flow is conveyed from the pressure side of the pumping device to the rotor chamber inlet, which is arranged on an upper side of the rotor chamber facing away from the pumping device and, after flowing around the rotor, is conveyed through the rotor chamber outlet to the pump outlet. The rotor space outlet is arranged on a lower side of the rotor space facing the pumping device.

The technical advantage of the pump is that by diverting the fluid flow from the pressure side of the pump to the top of the rotor and arranging the rotor space outlet on the underside of the rotor space, i.e. on the opposite side of the rotor, an effective flushing of the rotor space is achieved. which leads to improved hygienic conditions. In addition, the applicant has recognized that due to the rotational movement of the rotor, the fluid is conveyed outwards from the rotor chamber inlet due to centrifugal force, which leads to an improved Efficiency of the pump and also leads to an improved cleaning effect in the rotor space.

According to one exemplary embodiment, a first scavenging duct section of the scavenging duct system runs along the axis of rotation of the rotor, specifically in such a way that the first scavenging duct section comes to lie congruently with the axis of rotation of the rotor. As a result, the fluid flow can be guided centrally through the rotor in order to allow the fluid to exit at the top of the rotor.

According to one exemplary embodiment, the first scavenging duct section is tubular with a circular outer cross section, and the first scavenging duct section forms a bearing axis of the rotor. In particular, the first scavenging channel section is arranged in the pump in a rotationally fixed manner, i.e. it does not rotate with the rotor of the drive motor and thus forms a fixed axis of rotation for the rotor.

According to one exemplary embodiment, at least one conveying element is designed at least in sections as a hollow shaft and is rotatably mounted on the first scavenging duct section of the scavenging duct system. As a result, the conveying element can be slipped onto the first scavenging duct section and rotate around this first scavenging duct section. A plain bearing is preferably formed between the conveying element and the first scavenging channel section. The conveying element forms a first part of the plain bearing on the inside and the second part of the plain bearing on the outside of the first scavenging channel section. The pump can be designed in such a way that a liquid film (formed from the pumped liquid) is formed between the pumping element and the first scavenging channel section.

According to one exemplary embodiment, the hollow shaft of the conveying element is coupled to the rotor in order to introduce torque from the drive motor into the conveying element.

The hollow shaft preferably protrudes at least in sections into the rotor; in particular, the hollow shaft penetrates the rotor completely or essentially completely. As a result, the hollow shaft forms a large-area plain bearing between the conveying element and the first scavenging channel section, which serves as a bearing point for the rotor.

According to one exemplary embodiment, the rotor is pushed onto and/or pressed onto the hollow shaft. As a result, the torque can be reliably introduced into the conveying element in a technically simple manner.

According to one exemplary embodiment, the rotor chamber inlet is provided centered in the region of the upper side of the rotor facing away from the pumping device. As a result, the fluid is introduced into the rotor chamber above the rotor and has to flow downwards via the rotor outer surfaces in order to reach the rotor chamber outlet.

According to one embodiment, the rotor chamber is designed such that the fluid supplied to the rotor chamber via the rotor chamber inlet is deflected radially outwards in the rotor chamber relative to the axis of rotation of the rotor and is discharged downwards via the rotor outer surface in the direction of the rotor chamber outlet. Due to this flow around the rotor, a sufficiently good flushing of the rotor space is achieved without dead spaces. In addition, this flow around the rotor improves the efficiency of the pump due to its rotary motion.

According to the invention, the scavenging channel system is designed in such a way that the entire fluid flow delivered by the pumping device is delivered to the rotor chamber inlet. This has the technical advantage that a high volume flow is conveyed through the rotor chamber, which significantly improves the flushing effect.

The fluid is guided from the pressure side of the pumping device via a scavenging channel section with multiple angles along the axis of rotation of the rotor, introduced into the rotor chamber above the rotor and, after flowing around the rotor, is fed to the pump outlet via the rotor chamber outlet. In other words, the scavenging duct system forms a section of the conveying duct between the pump inlet and the pump outlet, via which the entire fluid volume flow conveyed by the pump device is conducted in order to scavenge the rotor space sufficiently well and to achieve the lowest possible pressure drop along the scavenging duct system. According to one embodiment, the conveying elements are formed by two meshing gears. This allows an effective pumping effect to be achieved.

According to one exemplary embodiment, a hood-like cover is provided, which encloses the rotor space at the top and on the circumference and delimits it in a fluid-tight manner in relation to the environment. As a result, a fluid-tight housing of the rotor can be achieved in a simple technical manner, so that it can be rinsed around without a fluid escaping.

According to one embodiment, the stator of the drive motor is arranged circumferentially around the hood-like cover. As a result, the drive motor extends beyond the cover, ie a first part, namely the rotor, is provided inside the cover and a second part, namely the stator, is provided outside the cover. According to a further aspect, the invention relates to a method for operating a pump. The pump includes a delivery channel through which a fluid can be delivered, the delivery channel having a pump inlet and a pump outlet. Between the pump inlet and the pump outlet there is a pump device for delivering the fluid, which has a suction side and a pressure side. The pumping device has two rotating conveying elements which engage in one another and by means of which a fluid flow is generated. The conveying elements are driven by a drive motor which is drivingly coupled to at least one conveying element in order to set it in rotation. The drive motor has a rotor and a stator, the rotor of the drive motor being provided in a rotor chamber that is fluidically sealed off from the environment. The rotor space is flushed with the pumped fluid via a flushing channel system. The scavenging channel system comprises a rotor chamber inlet and a rotor chamber outlet, with the fluid flow being conveyed from the pressure side of the pumping device to the rotor chamber inlet, which is arranged on an upper side of the rotor chamber facing away from the pumping device and, after flowing around the rotor, is conveyed through the rotor chamber outlet to the pump outlet, wherein the rotor space outlet is arranged on a lower side of the rotor space facing the pumping device.

The technical advantage of the method is that by diverting the fluid flow from the pressure side of the pump to the top of the rotor and locating the rotor space outlet at the bottom of the rotor space, ie on the opposite side of the rotor a effective rinsing of the rotor chamber is achieved, which leads to improved hygienic conditions. In addition, the applicant has recognized that due to the rotational movement of the rotor, the fluid is conveyed outwards from the rotor chamber inlet due to centrifugal force, which leads to an improved efficiency of the pump and also to an improved cleaning effect in the rotor chamber.

According to one exemplary embodiment of the method, the fluid for flushing the rotor chamber is conveyed along the axis of rotation of the rotor to an upper side of the rotor chamber facing away from the pumping device and, after flowing around the rotor along the rotor upper side and the rotor peripheral surface, is discharged at the rotor chamber outlet. Due to this flow around the rotor, a sufficiently good flushing of the rotor space is achieved without dead spaces.

According to the invention, the entire fluid flow delivered by the pump device is introduced from the pressure side of the pump device via a flushing channel section with multiple angles along the axis of rotation of the rotor above the rotor into the rotor chamber and, after flowing around the rotor, is fed to the pump outlet via the rotor chamber outlet. As a result, the rotor space can be flushed sufficiently well and the lowest possible pressure drop along the flushing channel system can be achieved.

In the context of the invention, the expressions “approximately”, “substantially” or “roughly” mean deviations from the exact value in each case by +/-10%, preferably by +/-5% and/or deviations in the form of changes that are insignificant for the function .

Further developments, advantages and possible applications of the invention also result from the following description of exemplary embodiments and from the figures.

The invention is explained in more detail below using a figure of exemplary embodiments. The figure shows an example of a sectional view of a pump 1 with a flushing channel system 6 for flushing a rotor space 5. The pump 1 can be used in particular in hygiene-sensitive applications with the requirement for hermetic sealing. The pump 1 can in particular be a coffee machine pump, i.e. it can be provided for use in a machine that prepares a coffee drink, in particular a fully automatic coffee machine.

The pump 1 includes a pumping device 3 which is motor-driven by means of a drive motor 4 . The pump device 3 comprises a pump inlet 2.1 and a pump outlet 2.2, with a delivery channel 2 running between the pump inlet 2.1 and a pump outlet 2.2, on which a fluid, in particular a liquid, is delivered by the pump device 3 (indicated by the arrows). To convey the fluid, two conveying elements 3 . 3 , which engage in one another and rotate, are provided, which are driven to rotate in opposite directions and thereby generate a fluid flow through the conveying channel 2 . The conveying elements 3.3 can be formed by gears, for example, so that the pump 1 is a gear pump.

To drive the conveyor elements 3.3, a drive 4 is provided, which includes a rotor 4.1 and a stator 4.2. The rotor 4.1 of the drive 4 is coupled to one of the conveying elements 3.3 in order to drive this conveying element 3.3 in rotation. The further conveying element 3.3 is also driven due to the meshing of the conveying elements 3.3, so that the conveying elements 3.3 rotate in opposite directions.

The pump 1 is constructed essentially like a sandwich and consists of a lower, first pump part 1.1, a second, middle pump part 1.2 and a third, upper pump part 1.3, with the second pump part 1.2 being arranged between the first and third pump part 1.1, 1.3 . The first pump part 1.1 comprises the pumping device 3 with the conveying elements 3.3, which are configured like gear wheels, for example, and by means of which the fluid is sucked in or pressurized. The pump inlet 2.1 and the pump outlet 2.2 are preferably also provided in the first pump part 1.1.

The second pump part 1.2 is designed as a separating device. It is essentially plate-shaped and separates the first pump part 1.1 from the third pump part 1.3. The second pump part 1.2 is fluid-tightly connected to the first pump part 1.1 by means of a seal 8 . The third pump part 1.3 includes the drive motor 4, which is provided for driving the pump device 3 by motor. The third pump part 1.3 has a cover 7, which is designed like a hood and is connected to the second pump part 1.2 in a fluid-tight manner by means of a seal 9. The cover 7, together with the second pump part 1.2, encloses a rotor chamber 5 in which the rotor 4.1 of the drive motor 4 is accommodated. The rotor chamber 5 is designed to be fluid-tight towards the environment and is designed to be of the To be pumped through pumping device 3 fluid to flush the rotor chamber 5. The rotor 4.1 can include one or more permanent magnets.

The stator 4.2 is provided circumferentially around the cover 7. The stator 4.2 is thus provided outside of the rotor chamber 5 through which fluid flows. The stator 4.2 can have several current-carrying windings or coils, by means of which the rotor 4.1 can be rotated.

The hygiene concept of the pump, in particular the flushing concept for flushing the rotor chamber 5, is described in more detail below:
The pump device 3 has a suction side 3.1 and a pressure side 3.2, both of which are provided in the first pump part 1.1. The suction side 3.1 is arranged upstream of the pair of conveying elements 3.3 seen in the direction of flow of the fluid, the pressure side 3.2 is arranged after the pair of conveying elements 3.3 seen in the direction of flow of the fluid.

In order to flush the rotor chamber 5 , the entire fluid flow conveyed by the pump device 5 is conveyed through the rotor chamber 5 in the exemplary embodiment shown. After flowing out of this rotor space 5, the fluid flow is conveyed to the pump outlet 2.2. The path of the fluid is represented in the figure by the plurality of arrows.

In order to conduct the fluid flow through the rotor space 5 , the pump 1 has a scavenging channel system 6 . The scavenging channel system 6 is designed in such a way that the fluid is conveyed from the pressure side 3.2 of the pumping device 3 to a rotor chamber inlet 6a which is provided in the upper region of the rotor chamber 5. The fluid flow is then deflected in such a way that it runs along the upper side of the rotor 4.1.1 and the Rotor outer surface 4.1.3 flows and at the rotor chamber outlet 6b, which is provided below the rotor 4.1, flows in the direction of the pump outlet 2.2. The scavenging channel system 6 thus forms part of the conveying channel 2, since all of the fluid conveyed by the pumping device is conducted through the rotor space 5, and not just a fraction of the fluid flow.

In more detail, the scavenging duct system 6 has a first scavenging duct section 6.1. This first scavenging channel section 6.1 runs along the axis of rotation DA of the rotor 4.1, i.e. the central longitudinal axis of the first scavenging channel section 6.1 coincides with the axis of rotation DA of the rotor 4.1. The rotor chamber inlet 6a is formed by the free end of the first scavenging channel section 6.1, which is arranged in the region of the upper side of the rotor chamber 5. The fluid can thus flow through the rotor 4.1 along its central vertical axis through the centrally arranged first scavenging channel section 6.1.

The first scavenging channel section 6.1 is straight and preferably designed as a round tube. As a result, the first scavenging channel section 6.1 forms a fixed axis as a bearing point around which the rotor 4.1 of the drive motor 4 can rotate.

As can be seen in the figure, at least one conveying element 3.3 has a hollow shaft 3.3.1. The conveying element 3.3 has, for example, in a lower region, a gear-like section from which the hollow shaft 3.3.1 protrudes upwards. For example, the gear-like section and the hollow shaft 3.3.1 are sections of a one-piece conveying element 3.3.

The conveying element 3.3, in particular the gear-like portion and the hollow shaft 3.3.1, has an inner longitudinal bore that is adapted to the outer diameter of the first scavenging duct section 6.1, so that the conveying element 3.3 can rotate around the first scavenging duct section 6.1 after it has been slipped on.

The conveying element 3.3, in particular the hollow shaft 3.3.1, has a length such that it protrudes through the second pump part 1.2 into the third pump part 1.3. The length of the hollow shaft 3.3.1 is preferably adapted to the length of the first scavenging channel section 6.1 in such a way that the hollow shaft 3.3.1 and the first scavenging channel section 6.1 end at the same height or essentially the same height in the upper region. The first scavenging duct section 6.1 is preferably longer than the conveying element 3.3, so that the fluid is introduced into the first scavenging duct section 6.1 through a scavenging duct section that is angled several times already below the conveying element 3.3. The fluid stream preferably flows through the conveying element 3.3 over its entire length.

In order to drive the conveying element 3.3 by the drive motor 4, the rotor 4.1 is preferably connected to the hollow shaft 3.3.1. In particular, the rotor 4.1 has a central opening into which the hollow shaft 3.3.1 protrudes at least in sections. The rotor 4.1 is preferably slipped or pressed onto the hollow shaft 3.3.1. As a result, the driving force of the rotor 4.1 can be transferred to the conveying element 3.3.

As previously described, the rotor chamber inlet 6a is provided in the upper area of the rotor chamber 5 or in the area of the upper side 4.1.1 of the rotor.

In order to achieve the best possible flow through the rotor space 5 without dead spaces, the rotor space outlet 6b is provided in the lower region of the rotor space 5, ie below the rotor 4.1. With that it has to Fluid flow around the rotor 4.1 from the rotor chamber inlet 6a provided in the upper region of the rotor chamber 5 in order to reach the rotor chamber outlet 6b.

In particular, the pump 1 is designed in such a way that the fluid is deflected radially outwards from the rotor chamber inlet 6a, i.e. the fluid flows radially outwards from the center of the rotor 4.1 on its upper side 4.1.1 (i.e. radially in relation to the axis of rotation DA of the rotor 4.1). A gap through which the fluid can flow is formed between the cover 7 and the top side 4.1.1 of the rotor.

The fluid flow is then deflected again by the cover 7 in such a way that the fluid flows downwards from the rotor top 4.1.1 through a gap formed between the cover 7 and the rotor outer surface 4.1.3. After flowing around the rotor 4.1, the fluid reaches the rotor chamber outlet 6b and flows out from there through a further flushing channel section to the pump outlet 2.2.

The invention has been described above using exemplary embodiments. It goes without saying that numerous changes and modifications are possible without leaving the scope of protection defined by the patent claims.

Reference List

1

pump

1.1

first pump part

1.2

second pump part

1.3

third pump part

2

conveyor channel

2.1

pump inlet

2.2

pump outlet

3

pumping device

3.1

suction side

3.2

pressure side

3.3

conveying element

3.3.1

hollow shaft

4

drive motor

4.1

rotor

4.1.1

rotor top

4.1.2

rotor bottom

4.1.3

rotor outer surface

4.2

stator

5

rotor space

6

irrigation channel system

6a

rotor chamber inlet

6b

rotor space outlet

6.1

first scavenging section

7

cover

8th

poetry

9

poetry

THERE

axis of rotation

Claims (13)

1. A pump comprising:

   - a conveyor channel (2) through which a fluid can be conveyed, comprising a pump inlet (2.1) and a pump outlet (2.2), a pumping device (3) for pumping the fluid being provided between the pump inlet (2.1) and the pump outlet (2.2), which pumping device has a suction side (3.1) and a discharge side (3.2);

   - the pumping device (3) having two rotating conveying elements (3.3) which engage in one another and by means of which a fluid flow is generated;

   - a drive motor (4), which is drivingly coupled to at least one conveying element (3.3) in order to set the latter in rotation, the drive motor (4) including a rotor (4.1) and a stator (4.2), the rotor (4.1) of the drive motor (4) being provided in a rotor chamber (5), which is fluidically sealed from the surroundings;

   - the pump (1) having a flushing channel system (6) for flushing the rotor chamber (5) with the delivered fluid, and the flushing channel system (6) comprising a rotor chamber inlet (6a) and a rotor chamber outlet (6b);

   characterized in that
   the flushing channel system (6) is designed in such a way that the fluid flow is delivered from the discharge side (3.2) of the pumping device (3) to the rotor chamber inlet (6a), which is arranged on an upper side of the rotor chamber (5) that faces away from the pumping device (3), and, after flowing around the rotor (4.1), is delivered through the rotor chamber outlet (6b) to the pump outlet (2.2), the rotor chamber outlet (6b) being arranged on a lower side of the rotor chamber (5) that faces the pumping device (3), and the flushing channel system (6) being designed in such a way that the entire fluid flow conveyed by the pumping device (3) is introduced from the discharge side (3.2) of the pumping device (3) via a multi-angled flushing channel portion along the axis of rotation (DA) of the rotor into the rotor chamber (5) above the rotor (4.1) and, after flowing around the rotor (4.1), is supplied to the pump outlet (2.2) via the rotor chamber outlet (6b).
2. The pump according to claim 1, characterized in that a first flushing channel portion (6.1) of the flushing channel system (6) runs along the axis of rotation (DA) of the rotor (4.1) in such a way that the first flushing channel portion (6.1) comes to lie congruently with the axis of rotation (DA) of the rotor (4.1).
3. The pump according to claim 2, characterized in that the first flushing channel portion (6.1) is designed in a tubular manner with a circular outer cross-section and in that the first flushing channel portion (6.1) forms a bearing axis of the rotor (4.1).
4. The pump according to claim 2 or 3, characterized in that at least one conveying element (3.3) is formed at least in portions as a hollow shaft (3.3.1) and is rotatably mounted on the first flushing channel portion (6.1) of the flushing channel system (6).
5. The pump according to claim 4, characterized in that the hollow shaft (3.3.1) of the conveying element (3.3) is coupled to the rotor (4.1) in order to achieve a force introduction from the drive motor (4) into the conveying element (3.3).
6. The pump according to claim 4 or 5, characterized in that the rotor (4.1) is plugged and/or pressed onto the hollow shaft (3.3.1).
7. The pump according to any one of the preceding claims, characterized in that the rotor chamber inlet (6a) is provided in centered fashion in the region of the rotor top side (4.1.1) facing away from the pumping device (3).
8. The pump according to any one of the preceding claims, characterized in that the rotor chamber (5) is designed in such a way that the fluid supplied to the rotor chamber (5) via the rotor chamber inlet (6a) is deflected radially outwards in the rotor chamber (5) with respect to the axis of rotation (DA) of the rotor (4.1) and is discharged downwards via the rotor outer surface (4.1.3) in the direction of the rotor chamber outlet (6b).
9. The pump according to any one of the preceding claims, characterized in that the conveying elements (3.3) are two gear wheels that engage in one another.
10. The pump according to any one of the preceding claims, characterized in that a hood-like cover (7) is provided which encloses the rotor chamber (5) on the upper and circumferential sides and delimits it in fluid-tight manner towards the surroundings.
11. The pump according to claim 10, characterized in that the stator (4.2) of the drive motor (4) is arranged circumferentially around the hood-like cover (7).
12. A method for operating a pump (1) comprising a conveyor channel (2), through which a fluid can be conveyed, the conveyor channel (2) having a pump inlet (2.1) and a pump outlet (2.2), a pumping device (3) being provided between the pump inlet (2.1) and the pump outlet (2.2) for pumping the fluid, which pumping device (3) has a suction side (3.1) and a discharge side (3.2), the pumping device (3) having two rotating conveying elements (3.3), which engage in one another and by means of which a fluid flow is generated, a drive motor (4) being provided which is drivingly coupled to at least one conveying element (3.3) in order to set the latter in rotation, the drive motor (4) having a rotor (4.1) and a stator (4.2), the rotor (4.1) of the drive motor (4) being provided in a rotor chamber (5) which is fluidically sealed from the surroundings, the rotor chamber (5) being flushed with the delivered fluid via a flushing channel system (6), the flushing channel system (6) comprising a rotor chamber inlet (6a) and a rotor chamber outlet (6b), the fluid flow being conveyed from the discharge side (3.2) of the pumping device to the rotor chamber inlet (6a), which is arranged on an upper side of the rotor chamber (5) that faces away from the pumping device (3) and, after flowing around the rotor (4.1), is delivered through the rotor chamber outlet (6b) to the pump outlet (2. 2), the rotor chamber outlet (6b) being arranged on a lower side of the rotor chamber (5) that faces the pumping device (3), and the entire fluid flow conveyed by the pumping device (3) being introduced from the discharge side (3.2) of the pumping device (3) via a multi-angled flushing channel portion along the axis of rotation (DA) of the rotor into the rotor chamber (5) above the rotor (4.1) and, after flowing around the rotor (4.1), being supplied to the pump outlet (2.2) via the rotor chamber outlet (6b).
13. The method according to claim 12, characterized in that for flushing the rotor chamber (5) the fluid is conveyed along the axis of rotation (DA) of the rotor to an upper side of the rotor chamber (5) that faces away from the pumping device (3) and, after flowing around the rotor (4.1) along the rotor upper side (4.1.1) and the rotor circumferential surface (4.1.2), is discharged at the rotor chamber outlet (6b).

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