Centrifugal pump with an electronics housing and at least two printed circuit boards

Description

[0001] The invention relates to a centrifugal pump with a two-part electronics housing, in which at least two circuit boards are spatially separated from each other and are electrically connected to each other by means of at least one electrical connection.

[0002] Modern centrifugal pumps, especially heating circulator pumps, are built with increasingly complex electronic controls for their operation. In particular, centrifugal pumps designed for energy-efficient operation include a frequency converter for speed control. The necessary electronics are housed within a dedicated electronics enclosure on the pump, which is typically designed in at least two parts for assembly purposes.

[0003] In addition to the components for pump control, the pump electronics can include additional electronic components for implementing a user interface. For manufacturing reasons, the user interface components and the pump control components can be housed on separate circuit boards, which are mounted separately within the electronics enclosure. Using separate, single-sided circuit boards is often more economical than using a single, double-sided board. For functional reasons, the two circuit boards are installed in the enclosure so that their unpopulated sides face each other.

[0004] For the necessary signal exchange and power supply of the components on both circuit boards, an electrical connection between the boards must be established. However, connecting them using electrical wires soldered to corresponding connection points on the boards has the disadvantage of adding an extra assembly step during manufacturing.

[0005] US 2017 / 302125 A1, DE 20 2015 008557 U1 and US 6 065 946 A disclose centrifugal pumps according to the preamble of claim 1.

[0006] Against this background, suitable means are being sought to simplify pump assembly and, in particular, the electrical connection of the two circuit boards.

[0007] This problem is solved by a centrifugal pump according to the features of claim 1. Advantageous embodiments of the centrifugal pump are the subject of the dependent claims. Furthermore, the problem is solved by a method according to the features of claim 14.

[0008] According to the invention, it is proposed to electrically connect the two circuit boards by means of at least one pin connector. Such a pin connector comprises, for example, one or more rigid, metallic pins that can be inserted into corresponding pin sockets on the circuit boards. During assembly, the pin connector is connected to the first circuit board, for example, before or after it is installed in the electronics housing. The connection of the pin connector to the first circuit board can, in principle, be made in any way; however, it is preferably inserted into a suitable pin socket or base on the first circuit board. The second circuit board can be pre-inserted into a second housing part. When the two housing parts are assembled, the remaining free end of the pin connector is inserted into the pin socket or base of the second circuit board and thus automatically connected.In principle, the second circuit board could also be inserted into the housing part that holds the first circuit board.

[0009] Inserting the pin connector into the pin socket requires a certain degree of precision during assembly. For example, if the circuit boards are only populated on one side and the unpopulated sides are facing each other, the free end of the pin connector must first be passed through relatively small holes in the second circuit board to be inserted into the pin socket on the populated side. Due to the comparatively small hole diameter, this assembly step becomes even more complicated.

[0010] For this reason, it is further proposed according to the invention to provide at least one assembly aid to simplify the insertion of the pin connector into the pin receptacle of the second circuit board. Such an assembly aid assists the assembler during the assembly of the second circuit board, in particular during the joining of the housing parts and the precise insertion of the pin connector into the pin receptacle of the second circuit board, thus preventing damage to the pin connector and simplifying and accelerating the assembly process.

[0011] Depending on the design, an insertion aid for the pin connector into the pin receptacle of the second circuit board or the corresponding holes in the second circuit board can be provided as an assembly aid. This could take the form of insertion chamfers in the opening area of ​​the pin receptacle. If the pin connector must be inserted through the holes in the circuit board, the edges of the holes facing the first circuit board can be designed with an insertion aid. For example, the openings of the holes in the second circuit board facing the first circuit board each have a circumferential chamfer that widens the hole diameter towards the first circuit board.

[0012] Alternatively or additionally, at least one of the housing parts can have at least two centering pins as an assembly aid. The length of the centering pins is dimensioned such that they are successively inserted through corresponding through-holes in the first and second circuit boards. During assembly of the first circuit board, it is thus centered and simultaneously fixed within the first housing part by the centering pins. The first circuit board already has the corresponding pin connection, which extends parallel to the centering pins in the direction of the second circuit board to be mounted. When the housing parts are joined or the second circuit board is mounted, the centering pins are inserted through the corresponding through-holes in the second circuit board, and in particular, the second circuit board is thereby pushed onto the centering pins in the direction of the first circuit board.The centering pins pre-center the second circuit board, allowing the pin connector to be precisely and securely inserted into the pin receptacle of the second board, or initially through the holes of the second board, during the subsequent assembly of the boards. Overall, this significantly simplifies the entire assembly process of the electronics housing, including the provision of the electrical connection between the two spatially separated circuit boards.

[0013] The electrical pin connector can have one or more metal pins that serve to provide multiple electrical contacts between the two circuit boards. These metal pins typically have a relatively small diameter, so the corresponding holes in the second circuit board also have a relatively small diameter.

[0014] Typically, the first housing part is made of plastic, and the centering pins molded into its inner wall are therefore also made of plastic. The housing part can be produced using plastic injection molding, which, due to the manufacturing process, results in the centering pins having draft angles. This means they usually have a longitudinal conical shape with a radius that decreases from the inner wall towards their free end. In this case, the through-holes in the second circuit board would have to be designed for the largest possible diameter of the centering pins. Consequently, at the beginning of the assembly process, there would be a relatively large amount of play between the tips of the centering pins and the through-hole in the second circuit board, making precise pre-centering difficult.

[0015] Against this background, it is proposed that an outer longitudinal section of the at least two centering pins be designed to be nearly cylindrical rather than conical. The outer longitudinal section is defined as the section around the free end of the centering pins, in particular the section that passes through the through-holes of the second circuit board during assembly. Specifically, this section should have no or only very slight draft angles, for example, in an angular range between 0° and a maximum of 1°, preferably between 0° and a maximum of 0.75°, ideally between 0° and a maximum of 0.5°. This results in the outer longitudinal section of the centering pins having a nearly constant diameter, which is matched to the bore diameter of the second circuit board.The resulting play therefore remains largely minimal throughout the entire sliding length of the second circuit board, thus enabling precise pre-centering of the second circuit board for the insertion of the pin connector into the corresponding holes or pin receptacle of the second circuit board.

[0016] Preferably, the length of the centering pins, starting from the mounted first circuit board to its free end, is greater than the total length of the pin connector, starting from the first circuit board, particularly the unpopulated underside of the first circuit board, to the mounted second circuit board. This ensures that during assembly, the second circuit board is first placed onto the centering pins, and only subsequently, with a further sliding motion of the second circuit board along the centering pins, is the pin connector passed through the holes of the second circuit board.

[0017] Advantageously, the outer length of the centering pins, i.e., the nearly cylindrical section, is longer than the total insertion depth of the pin connector into the pin receptacle or through the holes in the second circuit board. This ensures that the centering pins can be inserted through the holes in the second circuit board beforehand and that precise centering and stabilization of the second circuit board is maintained throughout the entire insertion movement of the pin connector.

[0018] Advantageously, the conical section of the at least two centering pins can have at least one step that divides the conical section into a first and a second conical section. The first conical section can be directly connected to the electronic housing part and have a larger diameter than the second conical section. Furthermore, the first conical section can be designed with a longitudinal bore. The longitudinal bore may be for manufacturing reasons. It ensures that sufficient material reaches the tip of the centering pins during injection molding. The longitudinal bore also ensures a homogeneous wall thickness in the longitudinal direction.

[0019] According to a preferred embodiment, after the first circuit board has been mounted, the step is located at the level of the through-hole of the first circuit board. Ideally, the step or the edge of the step is flush with the top surface of the circuit board.

[0020] According to a further preferred embodiment, the first circuit board comprises electronic components for implementing a human-machine interface (HMI), e.g., for controlling a display element and / or evaluating a control panel. Due to the comparatively moderate heat generation of the components during pump operation, the circuit board can be mounted on the first housing part, which is made of plastic. The second circuit board preferably comprises all or a large proportion of the electronic components for implementing the pump control, particularly using a frequency converter. The necessary power electronics require considerable cooling, so it is proposed that the second housing part be manufactured at least partially from metal, which serves as a heat sink to dissipate the generated waste heat.

[0021] The centrifugal pump itself can be designed as an inline pump. Inline pumps are centrifugal pumps whose discharge and suction ports are located in a straight pipeline. Centrifugal pumps are particularly well-suited for use as heating circulation pumps.

[0022] As already indicated above, the design of the electronic housing component with mounting aids enables precise assembly of the circuit boards and their simple electrical contacting. The objective is therefore also achieved by an assembly method according to the invention, which is preferably carried out during the assembly of the centrifugal pump according to the invention.

[0023] The procedure includes the following steps.

[0024] Positioning and fixing the first circuit board within the first housing part and positioning and fixing the second circuit board within the second housing part. The assembly sequence in which the circuit boards are inserted into the respective housing parts is irrelevant or only of minor importance to the invention. It is advantageous to insert at least one pin connector into the pin receptacle of the first circuit board before positioning the first circuit board. Alternatively, the pin connector can, of course, be connected to the second circuit board first. It is also conceivable that the pin connector is inserted into the pin receptacle of the circuit board only after the circuit board has been positioned and fixed in the respective housing part.

[0025] After positioning and fixing the circuit boards in the housing parts, the latter are joined together, with the free ends of the pin connector being inserted into the pin receptacle of the second circuit board. At least one assembly aid is used for this process.

[0026] Insertion aids in the opening area of ​​the holes in the second circuit board facilitate the precise insertion of the free ends of the pin connector during assembly. If centering pins are provided as an alternative or supplement, these are inserted through the corresponding through-holes in the first circuit board when positioning the first circuit board within the first housing part. When assembling the housing parts, the centering pins are again first inserted through the through-holes in the second circuit board, and the second circuit board is then slid onto the centering pins in the direction of the first circuit board until at least one pin connector is fully inserted into the pin receptacle of the second circuit board.

[0027] Further advantages and features of the invention will be explained in more detail below with reference to an exemplary embodiment shown in the figures. The figures show: Figure 1: a top view of the first housing part with the first circuit board inserted, Figure 2: a top view of the second housing part with the second circuit board inserted, Figure 3: a sectional view through the disassembled housing parts of the electronic housing with circuit boards inserted, and Figures 4a-4d: longitudinal sectional views through the centering pin during the assembly process in chronological order.

[0028] Figure 1Figure 1 shows a top view of the first housing part 10 of the electronics housing, which consists of a plastic housing component. The top view shows the open side of the housing part 10 and the first electronic circuit board 12 inserted into the housing part 10 for implementing the user interface, hereinafter also referred to as the HMI board 12. The circuit board 12 is placed on corresponding bearing points of the plastic housing 10 and additionally screwed to the housing part 10 for fixation. Furthermore, the circuit board 12 is populated on one side, with the populated side of the circuit board facing the inner wall of the plastic housing 10. In the top view of the Figure 1 Therefore, the unpopulated underside of the circuit board is visible.

[0029] Figure 2Figure 1 shows a top view of the open side of the second housing part 11, which is designed here as a metallic heat sink. The heat sink 11 serves to accommodate and support a second electronic circuit board 13. The circuit board 13 forms the main board of the centrifugal pump according to the invention, in this example implemented as a heating circulator pump, and includes the necessary components for pump control, including a frequency converter for speed control. The electronic components required for this include, among other things, power modules whose waste heat can be dissipated to the environment via the heat sink 11. The main circuit board 13 is also only populated on one side, and—similar to the circuit board 12—is installed with the populated side facing downwards, i.e., the components are facing the inner wall of the heat sink 11. The reason for this is to ensure better thermal contact between the components requiring cooling and the heat sink 11.

[0030] Since the pump power supply is provided via the main board 13, the HMI board 12 must be electrically connected to the main board 13 for power supply. Signal exchange between the two boards 12 and 13 must also be possible. The electrical connection is achieved using a pin connector 15, which has a multitude of parallel metallic pins that can be connected at their ends to corresponding pin receptacles 15a on the first and second boards 12 and 13. The connection is purely mechanical. For this purpose, board 12 has a corresponding multitude of small holes 14 through which the pins of the pin connector 15 can pass. The socket 15a of the pin connector 15 rests on the populated side of board 12.On the unpopulated side of the circuit board 12, a counter adapter 15b is provided, which can be an integral part of the pin connector 15 or alternatively could be slid on afterwards after the pin connector 15 has been inserted into the socket 15a.

[0031] To connect the mainboard 13, the metal pins of the pin connector 15 must be inserted through the corresponding holes 18 of the mainboard 13. The connection is secured using a socket 15 and the mating adapter 15b, which, as previously described, can be an integral part of the pin connector 15 or can be mounted separately. During assembly, the pin connector 15 is first pre-mounted on the HMI board 12, which is then inserted into the plastic housing 10 and secured there. The mainboard 13 is pre-mounted in the heat sink 11. When joining the housing parts 10 and 11, care must be taken to ensure that the tips of the pin connector 15 are inserted into the holes 18 of the mainboard 13.

[0032] To simplify this process step, at least one assembly aid is provided. It may be sufficient to chamfer the opening area of ​​the bores 18 in the mainboard 13, thus creating insertion aids for the tips of the pin connector 15. This increases the tolerance range when feeding the pin connector to the bores 18. In the illustrated embodiment, two identical plastic domes 20, or centering pins, are formed on the plastic housing part 10 as further assembly aids for pre-centering the mainboard 13 together with the heat sink 11. These domes project vertically from the inside of the housing towards the heat sink 11. The presence of these centering pins 20 is optional to the use of the insertion aids.

[0033] The centering pins 20 are inserted through corresponding through-holes 17 in the HMI board 12 during pre-assembly. The main board 13 also has additional through-holes 16 in the area around the holes 18 for the pin connector 15. The centering pins are inserted through these holes when the housing parts 10 and 11 are assembled, thus pre-centering the second board 13 relative to the first board 12. During the further assembly of the housing parts 10 and 11, the tips of the pin connector 15 then engage precisely in the holes 18.

[0034] The Figures 4a to 4dThe figures document the chronological sequence of the assembly of the housing parts 10 and 11. Furthermore, the figures illustrate the special design of the centering pins 20. The two centering pins 20 are identical and comprise a first longitudinal section 20a, which extends from the base of the plastic housing 10 to a first step 21. Due to the manufacturing process, this longitudinal section 20a has a conical shape with a diameter that decreases in the overhang length. This is due to the draft angles required in the injection molding process. A second longitudinal section 20b adjoins the first longitudinal section 20a. Because of the step 21, this second section has a sharply reduced diameter and tapers in the overhang direction due to its conical shape. The step 21 is almost flush with the opening edge of the bores 17 in the circuit board 12.The opening diameter of the through holes 17 is matched to the diameter range of the length section 20a of the plastic domes 20.

[0035] Following length section 20b, an outer length section 20c is added, which ideally has no or only minimal draft angles. The angle of the draft angles there is 0° or nearly 0°, so that the centering pins 20 are approximately cylindrical in this length section. The through-holes 16 of the main plate 13 for receiving the centering pins 20 are matched to the diameter of length section 20c. This results in minimal clearance between the centering pins 20 and the through-hole 16 and extremely precise pre-centering of both the second plate 13 and the housing part 11.

[0036] The maximum insertion depth of the pin connector 15 through the holes 18 is limited by the mating adapter 15b of the pin connector 15, which abuts the unpopulated side of the circuit board 13. The length of the connector 15 from the mating adapter 15b to the outer tip of the pin connector 15 is shorter than the outer length 20c of the centering pins 20. This ensures that, during assembly, the centering pins 20 engage in the corresponding through holes 16 of the main circuit board 13 before the metal pins of the pin connector 15 can be inserted into the corresponding holes 18 (see figure). Figures 4a, b ).

[0037] On the populated side of the mainboard 13 is the corresponding socket 15a, through which the tips of the pin connector 15 emerging from the holes 18 are passed until the mating adapter 15b rests on the unpopulated side of the board 13 ( Figure 4d ).

[0038] The first longitudinal section 20a has a longitudinal bore 22, which is a technical necessity due to the plastic injection molding process used to manufacture the plastic housing part 10. This bore 22 ensures a homogeneous wall thickness of the plastic dome 20 along its entire length. It also ensures that the outer longitudinal section 20c of the injection mold can be filled with sufficient plastic material.

Claims

1. Centrifugal pump with a two-part electronics housing (10, 11), in which at least two circuit boards (12, 13), which are mounted spatially separated from each other, are mounted and at least one electrical connection (15) is provided between the circuit boards (12, 13), wherein the electrical connection is established by means of at least one rigid pin connector (15), the ends of which are or can be connected to suitable pin receptacles (15a) of the first and the second circuit board (12, 13), wherein one or more mounting aids (20) are provided in order to simplify introduction of the pin connector (15) into the pin receptacle (15a) of the first and / or second circuit board (12, 13), characterized in that insertion bevels are provided as mounting aids, the insertion bevels being formed in the edge region of holes (18) in the first or second circuit board (12, 13), through which holes the pin connector (15) is to be passed for insertion into the pin receptacle (15a).

2. Centrifugal pump according to Claim 1, characterized in that at least one of the housing parts (10) has, as a mounting aid, at least two centring pins (20), the length of which is such that the centring pins (20) can be or are passed successively through associated passage holes (17, 16) in the first and second circuit board (12, 13).

3. Centrifugal pump according to Claim 2, characterized in that the centring pins (20) are conical for production-related reasons, but an outer length portion (20c) in the region of the exposed ends is virtually cylindrical, in particular has demoulding bevels in an angular range of between 0° and 1°, preferably of between 0° and 0.75°, ideally of between 0° and 0.5°.

4. Centrifugal pump according to Claim 2 or 3, characterized in that the length of the centring pins (20) from the mounted first circuit board (12) to its free end is greater than the length of the pin connection starting from the first circuit board (12) to the contacted second circuit board (13).

5. Centrifugal pump according to Claim 3 or 4, characterized in that the outer length portion (20c) of the centring pins (20) is longer than the insertion depth of the pin connector (15) into the pin receptacle (15a) of the second circuit board (13).

6. Centrifugal pump according to any of Claims 3 to 5, characterized in that that the conical portion has at least one step (21), which divides the conical portion into a first (20a) and second cone portion (20b), wherein the first cone portion (20a) directly adjoins the housing part (10) and is larger in terms of diameter than the second cone portion (20b).

7. Centrifugal pump according to Claim 6, characterized in that the first cone portion (20a) is designed with a longitudinal bore (22).

8. Centrifugal pump according to Claim 6 or 7, characterized in that the step (21) lies in the region of the passage hole (17) in the first circuit board (12), in particular the step (21) terminates flush with the hole opening in the circuit board (12), in the installation position of the first circuit board (12).

9. Centrifugal pump according to any of the preceding claims, characterized in that the first and / or second circuit board (12, 13) are / is populated on one side and the non-populated circuit board sides face each other.

10. Centrifugal pump according to any of the preceding Claims 3 to 9, characterized in that the passage holes (16) in the second circuit board (13) are exactly adapted to the diameter of the outer length portion (20c) of the centring pins (20), in particular the clearance present between the centring pin (20) and the passage hole (16) during passage is reduced to a minimum.

11. Centrifugal pump according to any of the preceding claims, characterized in that the first housing part (10) is made of plastic.

12. Centrifugal pump according to any of the preceding claims, characterized in that the first circuit board (12) has electronic components for providing a user interface and the second circuit board (13) has electronic components for implementing pump control, in particular pump control with speed regulation.

13. Centrifugal pump according to any of the preceding claims, characterized in that the centrifugal pump is an inline pump, in particular a heating circulation pump.

14. Method for assembling an electronics housing for a centrifugal pump according to any of the preceding claims, comprising the steps of: a. positioning and fixing the first circuit board (12) within the first housing part (10), b. positioning and fixing the second circuit board (13) within the second housing part (11), c. inserting the at least one pin connector (15) into the pin receptacle (15a) of the first or second circuit board (12, 13) before or after the corresponding circuit board (12, 13) is fixed within the housing part (10, 11), and d. joining the housing parts (10, 11) while simultaneously establishing the electrical connection between the circuit boards (12, 13) by means of the at least one pin connector (15) using the at least one mounting aid (18a, 20) formed as an insertion bevel in the edge region of holes (18) in the first or second circuit board (12, 13), through which holes the pin connector (15) is passed for insertion into the pin receptacle (15a).

15. Method according to Claim 14, characterized in that, when positioning the first circuit board (12) within the first housing part (10), centring pins (20) are passed through associated passage holes (17) in the first circuit board (12) and, when joining the housing parts (10, 11), the centring pins (20) are passed through passage holes (16) in the second circuit board (13), until the at least one pin connector (15) is fully inserted into the pin receptacle (15) of the second board (13).

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