Electric fluid pump and method for manufacturing a housing of the electric fluid pump

Abstract

The invention relates to an electric fluid pump comprising: an electric motor (30) which has a motor stator (32) and a motor rotor (34); a pump rotor (40) which is connected to the motor rotor (34) in a torque-transmitting manner; a control module (50) which is designed to control the electric motor (30); and a housing (20) which defines a housing interior (21) that is divided into a dry chamber (T) and a wet chamber (N), wherein the dry chamber (T) is separated from the wet chamber (N), at least in certain areas, by a separate partition element (60), wherein a housing component (26) made of plastic is overmoulded onto a peripheral overmoulding region (U) of the partition element (60), and wherein the partition element (60) is coated, at least in the overmoulding region (U), with a bonding lacquer layer (641, 642).

Description

[0001] Hella GmbH & Co. KGaA

[0002] Electric liquid pump and method for manufacturing a housing for the electric liquid pump

[0003] Description

[0004] The invention relates to an electric liquid pump with an electric motor comprising a motor stator and a motor rotor, a pump rotor connected to the motor rotor in a torque-transmitting manner, a control module designed to control the electric motor, and a housing defining an interior space which is divided into a dry space and a wet space, wherein the pump rotor, the motor rotor and / or the motor stator are arranged in the wet space and a control module for controlling the electric motor is arranged in the dry space, and wherein the dry space is separated from the wet space at least partially by a separating element, and wherein a housing component made of plastic is injection-molded onto an edge injection area of ​​the separating element.

[0005] Such electric liquid pumps typically comprise an electric motor and a control module. Both the electric motor and the control module, particularly the power electronic components of the control module, heat up during operation. To cool the electric motor, i.e., the motor rotor and / or the motor stator, a liquid flow is diverted from a pump chamber forming a wet chamber, in which a pump rotor transmitting torque to the motor is located, and directed to the electric motor. The liquid flows around and / or through the motor stator and / or the motor rotor. Thus, the electric motor is cooled directly by the liquid flow. The liquid flow diverted to the electric motor also serves to cool the control module, which is located in the dry chamber and is therefore not directly exposed to the liquid.The control module is cooled in such a way that the control module is thermally cooled by the separating element, which is the Hella Gi. P09133A-WO

[0006] The wet chamber is separated from the dry chamber and is made of a thermally conductive material. The liquid flow is directed along the separating element. This transfers the heat generated by the control module during operation to the separating element, which is then dissipated by the liquid flow.

[0007] Electrically conductive, non-insulated elements forming the control module are arranged in the dry chamber, necessitating a fluid- and pressure-tight seal between the dry chamber and the wet chamber. Such a seal can be achieved via a separate sealing element or by injection molding the plastic housing onto the separating element. An example of such an electric liquid pump with a plastic housing injection molded onto the separating element is disclosed in WO 2023 / 237203 A1.

[0008] The problem is that the connection between the plastic housing and the separating element, achieved through overmolding or injection molding, poses a risk of leakage, allowing liquid to enter the dry chamber. In particular, due to differing thermal expansion rates between the plastic housing or housing component and the separating element, cracks or fissures can form after temperature changes. This allows liquid to seep through tiny channels via capillary action from the wet chamber into the dry chamber. If liquid enters the dry chamber, there is a risk of a short circuit in the control module and consequently, an unwanted failure of the liquid pump.

[0009] The object of the invention is therefore to provide an electric liquid pump in which the ingress of liquid or moisture from the wet room into the dry room can be prevented in a simple and reliable manner. Hella Gi P09133A-WO

[0010] The problem is solved by the features of claim 1.

[0011] According to the invention, the separating element is coated, at least in the injection area, with a baked-on coating, preferably made of an epoxy resin. This coating serves to create an elastic layer between the housing component and the separating element, which, in the injection area of ​​the separating element, is bonded to the plastic housing and the separating element, particularly by a material bond. In its cured state, the baked-on coating is elastic enough to reliably compensate for differences in thermal expansion between the housing component and the separating element through elastic deformation of the coating. This reliably prevents cracks or gaps from forming during operation of the liquid pump, thereby preventing unwanted leakage of the liquid from the wet chamber into the dry chamber and unwanted failure of the control module due to a short circuit.

[0012] A curing lacquer layer is used to bond several components together in a multi-stage manufacturing process. First, a component, in this case the separating element, is coated with the curing lacquer, which then dries. The actual curing process then takes place, where the curing lacquer, applied to the separating element and partially dried, is hardened by heat and, if necessary, pressure, resulting in a material bond between the two components, in this case the housing component and the separating element. In this particular case, the curing process, i.e., the heating of the curing lacquer, is achieved by the warm, molten plastic material from which the housing component is manufactured, i.e., injection molded.The baking lacquer layer is preferably designed in such a way that it hardens in several stages, wherein in a first stage the baking lacquer layer bonds with the separating element through a drying process and in a second stage of hardening through the Hella Gi. P09133A-WO

[0013] Heat input through the injection molding material connects with the housing component.

[0014] In this way, the housing component is manufactured and a reliable fluid-tight connection between the housing component and the separating element is created in a single step, namely during the injection molding of the housing component. This allows a reliable fluid-tight connection between the housing component and the separating element to be achieved in a simple and cost-effective manner.

[0015] Preferably, the separating element is made of a metal, in particular a metal with high thermal conductivity. The separating element is preferably designed as a sheet metal part, and a sheet metal separating element can be manufactured simply and cost-effectively, in particular by stamping.

[0016] Preferably, the control module is thermally connected to the separating element. In a preferred embodiment, the control module is thermally connected to the separating element via a thermal interface material. This thermal interface material can be a thermally conductive mat or thermal paste arranged between the control module and the separating element, and it must have high thermal conductivity. The thermal interface material eliminates an undesirable air gap, which would reduce heat transfer between the control module and the separating element, thus ensuring a reliable level of heat transfer between the control module and the separating element at all times. This reliably prevents the control module from overheating.Preferably, the control module comprises a printed circuit board and at least one heat-generating element arranged on the printed circuit board, in particular a power semiconductor element, for example a MOSFET, wherein the heat-generating element is arranged on a side of the printed circuit board facing the separation element and is thermally connected to the separation element. P09133A-WO is connected. The thermal coupling between the heat-generating element and the separating element is achieved primarily through a thermal conductor. Several heat-generating components can also be thermally coupled to the separating element. Separate coupling of the heat-generating components to the separating element allows the heat from each individual component to be dissipated almost independently.

[0017] Preferably, the housing component has a circumferential projection extending radially inwards, with the separating element being connected to the projection circumferentially. In a preferred embodiment, the housing component surrounds the injection area of ​​the separating element in a clamping manner, with a layer of baked-on varnish present on both sides of the separating element. This results in a relatively large contact area between the separating element and the housing component, meaning that any leakage flow would have to pass through two areas coated with a baked-on varnish layer to reach the drying chamber. In this way, a particularly reliable seal of the drying chamber can be provided.

[0018] The problem is further solved by a method for manufacturing a housing for an electric liquid pump according to any one of claims 1 to 8, wherein a separating element is first provided, the separating element is then coated with a baked-on lacquer layer in the injection area, and finally a housing component is injection-molded, the housing component being injection-molded onto the injection area. For the advantages, reference is made to the preceding paragraphs.

[0019] Such a manufacturing process can be achieved, for example, by placing the separating element, which is already coated with the baking lacquer layer, into the injection mold before the injection molding process. The injection molding process then takes place, and the housing component is produced. Hella Gi P09133A-WO

[0020] Preferably, the separating element, which is made in particular from a sheet metal part, is coated with the baked-on lacquer layer, especially one side completely, and then punched out. The separating element is then placed in the injection mold to produce the housing component.

[0021] The invention will be explained in more detail below with reference to the attached drawings.

[0022] This shows:

[0023] Fig. 1 An electric liquid pump in cross-section, and

[0024] Fig. 2 Section of the liquid pump from Fig. 1 in cross-section.

[0025] Fig. 1 shows an electric liquid pump 10, for example for a cooling system of a vehicle.

[0026] The liquid pump 10 has a multi-part housing 20, an electric motor 30, a pump rotor 40 and an electrical control module 50.

[0027] The housing 20 comprises several housing components 22, 24, 26, 28, wherein a first housing component 22 forms a pump housing element 221, a second housing component 24 forms a motor housing element 241, a third housing component 26 forms an electronics housing element 261, and a fourth housing component 28 forms a cover 281. The housing components 22, 24, 26, 28 together define a housing interior 21. All housing components 22, 24, 26, 28 are made of plastic and are, in particular, injection-molded. The pump housing element 221, the motor housing element 241, and the electronics housing element 261 are fluid-tightly connected to one another, in particular by screws or welds, preferably friction welds. The cover 281 is also fluid-tightly connected to the electronics housing element 261, in particular by screws. The Hella Gi P09133A-WO

[0028] Motor housing element 241 comprises a wall 242, which separates a motor chamber M from a pump chamber P. Electronics housing element 261 comprises a wall 271, which separates the motor chamber M from an electronics chamber E. The pump chamber P can be connected to a cooling system (not shown) via an intake port 231 and an outlet port 232 of the pump housing element 22.

[0029] The electric motor 30 is arranged in the motor compartment M and comprises a stator 32 and a rotor 34. The rotor 34 comprises a rotor body 341 and a rotor shaft 342. The rotor body 341 is non-rotatably connected to the rotor shaft 342 via a bushing 343. The rotor shaft 342 is rotatably mounted to the wall 242 via a bushing 36. The stator 32 is embedded in the electronic housing element 261.

[0030] The pump rotor 40 is arranged in the pump housing element 221, i.e., in the pump chamber P, and is non-rotatably connected to the rotor shaft 342, which projects from the motor chamber M into the pump chamber P. The pump rotor 40 is fixedly mounted on a metallic bushing 42, which is fixedly connected to the rotor shaft 342, so that the pump rotor 40 is non-rotatably connected to the rotor shaft 342 via the bushing 42.

[0031] The control module 50 is located in the electronics compartment E and comprises a printed circuit board 52 and several electronic components 541, 542, 543 arranged on the printed circuit board 52. The control module 50 has several electrically non-isolated components, so the electronics compartment E must be fluid-tightly separated from the engine compartment M.

[0032] During operation of the electric coolant pump 10, the electric motor 30 is cooled by a fluid flow diverted from the pump chamber P. The control module 50 is also cooled by the fluid diverted from the pump chamber P during operation. Hella Gi P09133A-WO

[0033] For this purpose, one or more through-holes 234 are provided in the wall 242, forming a connection between the pump chamber P and an annular chamber R bounded by the motor housing element 241 and the electronics housing element 261. A liquid can be conveyed from the pump chamber P into the annular chamber R through the through-holes 234. The annular chamber R is connected to the motor chamber M by one or more radial through-holes 262 formed in the electronics housing element 261.

[0034] Furthermore, the bushings 343, 36, 42 each have one or more grooves 344, 361, 421, which together with the rotor shaft 342 form through-holes through which the fluid flowing into the motor chamber M can flow into the pump chamber P. Thus, the pump chamber P, the motor chamber M and the annular chamber R together form a wet chamber N, while the electronics chamber E forms a dry chamber T.

[0035] During operation, a liquid can flow from the pump chamber P through the through-opening 234 into the annular chamber R and from the annular chamber R into the motor chamber M. From the motor chamber M, the liquid flowing along the wall 271 can flow back into the pump chamber P via the grooves 344 of the bushing 343, the grooves 361 of the bushing 36, and the grooves 421 of the bushing 42.

[0036] This provides cooling of the control module 50 via the wall 271 and the fluid flowing through the motor chamber M and along the wall 271, whereby the control module 50, i.e., the electronic component 541, is thermally connected to the wall 271. To increase heat transfer between the control unit 50 and the fluid flowing along the wall 271, the wall 271 is formed by a separate separating element 60, which has a relatively high thermal conductivity. The housing component 26, or the electronic housing element 261, i.e., the projection 272, is injection-molded onto an edge-side injection area U of the separating element 60. Hella GmbH & Co. KGaA

[0037] Fig. 2 shows a section of the electric coolant pump 10 in the area of ​​the separating element 60.

[0038] The separating element 60 is circular and made of a metallic material with a high thermal conductivity. The separating element 60 is firmly connected to the electronic housing element 261 by being overmolded by the electronic housing element 261 in an edge-side injection area U, or by the electronic housing element 261 being overmolded onto the edge-side injection area U of the separating element 60. The overmolding of the separating element 60 is designed such that the electronic housing element 261 clamps around the injection area U, so that the electronic housing element 261 rests against the separating element 60 on both sides.

[0039] To reliably provide a fluid-tight connection between the separating element 60 and the electronic housing element 261, the separating element 60 is coated on both sides with a baked-on varnish layer 641, 642. The baked-on varnish layer 641, 642 is made of an epoxy resin and serves to create an elastic layer between the electronic housing element 261 and the separating element 60. In their cured state, the baked-on varnish layers 641, 642 are sufficiently elastic to reliably compensate for differences in thermal expansion between the housing component 26 or the electronic housing element 261 and the separating element 60 through elastic deformation of the baked-on varnish layers 641, 642. This reliably prevents cracks or gaps from forming during the operation of the liquid pump 10, thereby preventing unwanted leakage of the liquid from the wet chamber N into the dry chamber T.

[0040] In other words, if the connection between the electronic housing element 261 and the separating element 60 is achieved by overmolding or injection molding, there is a risk of leakage, Hella GmbH & Co. KGaA Due to the different thermal expansion rates of the plastic electronic housing element 261 and the metallic separating element 60, gaps or cracks can form after temperature changes, allowing liquid to penetrate from the wet chamber N into the dry chamber T via capillary action through minute channels. The elasticity of the baked-on lacquer layers 641 and 642 compensates for such thermal expansions and thus prevents the formation of any gaps and cracks.

[0041] The electronic housing element 261, in combination with the separating element 60, is manufactured as follows: First, the separating element 60 is prepared, a sheet metal part is coated on both sides with the baking lacquer layer 641, 642, and once the baking lacquer layers 641, 642 have dried, the separating element 60 is punched out of the coated sheet metal. Subsequently, the housing component 26 is injection molded, with the housing component 26 being injection molded onto the separating element 60, i.e., onto the injection area U. During this process, the baking lacquer layers 641, 642, which have been applied to the separating element 60 and partially dried, are completely cured by the heat provided by the warm, molten plastic material of the electronic housing element 261, thereby bonding the electronic housing element 261 and the separating element 60 together via the baking lacquer layers 641, 642.

[0042] Hella GmbH & Co. KGaA

[0043] Reference symbol list

[0044] 10 Electric liquid pump

[0045] 20 cases

[0046] 21 Interior of the housing

[0047] 22 Housing component

[0048] 221 Pump housing element

[0049] 231 Intake manifold

[0050] 232 outlet nozzles

[0051] 234 Passage opening

[0052] 24 Housing components

[0053] 241 Motor housing element

[0054] 242 wall

[0055] 26 Housing component

[0056] 261 Electronic housing element

[0057] 262 Passage opening

[0058] 271 wall

[0059] 272 Radial Lead

[0060] 28 Housing components

[0061] 281 lids

[0062] 30 electric motor

[0063] 32 Motor stator

[0064] 34 Motor rotor

[0065] 341 Rotor bodies

[0066] 342 Rotor shaft

[0067] 343 socket

[0068] 344 Nut

[0069] 36 socket

[0070] 361 Nut

[0071] 40 Pump rotor

[0072] 42 Bushing Hella GmbH & Co. KGaA

[0073] 421 Nut

[0074] 50 Control module

[0075] 52 circuit boards

[0076] 541 Electronic component

[0077] 542 Electronic component

[0078] 543 Electronic component

[0079] 60 separating element

[0080] 641 Baking varnish layer

[0081] 642 Baking varnish layer

[0082] 66 Thermal conductors

[0083] E Electronics Chamber

[0084] M Engine chamber

[0085] N Wet room

[0086] P Pump chamber

[0087] R ring chamber

[0088] Dry room

Claims

Hella GmbH & Co. KGaA P09133A-WO Electric liquid pump and method for manufacturing a housing for the electric liquid pump Patent claims 1. An electric liquid pump comprising an electric motor (30) having a motor stator (32) and a motor rotor (34), a pump rotor (40) connected to the motor rotor (34) for torque transmission, a control module (50) configured to control the electric motor (30), and a housing (20) delimiting an interior housing space (21) which is divided into a dry space (T) and a wet space (N), wherein the pump rotor (40), the motor rotor (34) and / or the motor stator (32) are arranged in the wet space (N) and the control module (50) for controlling the electric motor (30) is arranged in the dry space (T), wherein the dry space (T) is separated from the wet space (N) at least partially by a separate separating element (60), and wherein a housing component (26) of the housing (20) made of plastic is attached to an edge-side injection area. (U) of the separating element (60) is injection-molded, characterized in thatthat the separating element (60) is coated with a baking lacquer layer (641, 642) at least in the injection area (U).

2. Electric liquid pump according to claim 1, characterized in that the baking varnish layer (641, 642) is an epoxy resin. Hella GmbH & Co. KGaA P09133A-W 3. Electric liquid pump according to claim 1 or 2, characterized in that the separating element (60) is made of a metal.

4. Electric liquid pump according to claim 3, characterized in that the separating element (60) is a sheet metal part.

5. Electric liquid pump according to one of the preceding claims, characterized in that the control module (50) is thermally connected to the separating element (60).

6. Electric liquid pump according to claim 5, characterized in that the control module (50) is thermally connected to the separating element (60) via a thermal conductor (66).

7. Electric liquid pump according to claim 6, characterized in that the control module (50) has a printed circuit board (52) and at least one heat-generating element (541) arranged on the printed circuit board (52), wherein the heat-generating element (541) is arranged on a side of the printed circuit board (52) facing the separating element (60) and is thermally connected to the separating element (60).

8. Electric liquid pump according to one of the preceding claims, characterized in that the housing component (26) surrounds the edge-side injection area (U) of the separating element (60) in a clamp-like manner, wherein on both sides of the Hella GmbH & Co. KGaA Each separating element (60) has a layer of baking lacquer (641 , 642).

9. Method for manufacturing a housing for an electric liquid pump according to any one of claims 1 to 8, comprising the following steps: Providing a separating element (60), Coating the separating element (60) at least in the injection area (U) with a baked enamel layer (641 , 642), and Injection molding of a housing component (26), wherein the housing component (26) is injected onto the injection area (U) of the separating element (60).

10. Method according to claim 9, characterized in that the separating element (60) is coated with the baking varnish layer (641 , 642) and is then punched out.

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