TEMPERATURE CONTROL DEVICE FOR A BATTERY STORAGE MODULE

Description

[0001] The present invention relates to a temperature control device for a battery storage module, for example in a traction battery of an electric vehicle.

[0002] Temperature control of battery storage modules serves in particular to dissipate waste heat generated during charging or power consumption via a heat exchanger using a temperature control medium.

[0003] The cooling circuits of battery-electric vehicles are highly complex, featuring numerous pipe branches, fluid connections, and various pumps and valves. Dividing the overall cooling circuit's cross-sectional area into pipe branches, such as networks of cooling channels with correspondingly smaller, potentially capillary, cross-sections, requires a significantly higher delivery pressure than in the comparatively large-volume cooling circuit of an internal combustion engine. Such branched cooling circuit structures are increasingly common in the design of battery storage modules, where numerous battery cells are cooled through small channels.

[0004] One object of the present invention is to create an alternative technique for temperature control of a battery storage module with a branched temperature control circuit.

[0005] Another aspect of the task is to provide a suitable technical solution that can be implemented cost-effectively in mass production of large quantities.

[0006] The object of the invention is achieved by a temperature control device with the features of claim 1. The temperature control device for a battery storage module is characterized in particular by the fact that a pump of the temperature control device comprises a spindle housing with an inlet opening and an outlet opening; and at least one screw spindle which is rotatably mounted in the spindle housing and coupled to an electric motor; wherein the electric motor is designed as a dry-running motor and is arranged separately from the spindle housing.

[0007] The temperature control device according to the invention enables higher delivery pressures in the temperature control circuit than are achievable with a centrifugal pump. Compared to centrifugal pumps, the pump of the temperature control device according to the invention provides a higher delivery pressure potential for cooling circuits or temperature control circuits with branched pipes and corresponding bottlenecks.

[0008] In centrifugal coolant pumps, the axial gap between the impeller and the pump chamber represents the greatest weak point regarding the seal between the suction and discharge sides of the pump. Leakage at this axial gap and the corresponding loss of flow rate increase at higher discharge pressures. Achieving an effective sealing gap depends on the dimensional accuracy of the axial fit between the impeller and the housing after assembly. When manufacturing centrifugal pumps for higher discharge pressures, the effort and costs associated with ensuring a suitable axial sealing gap reach the limits of economic viability. Otherwise, volumetric efficiency at higher discharge pressures is compromised.

[0009] In the screw spindle mechanism of the temperature control device according to the invention, the effective sealing gap extends over the entire length of the screw spindles between a suction side and a pressure side. Maintaining a specific axial gap dimension is not necessary, since the screw spindles are pressed against a contact surface on the suction side during operation.

[0010] Furthermore, the screw spindle mechanism of the temperature control device according to the invention has a smaller acoustically effective surface area in relation to the surrounding housing compared to centrifugal pumps. The rotational movement of the impeller blades generates speed-dependent pressure fluctuations on the chamber walls of the pump chamber, which can lie in a resonant frequency range of housing components.

[0011] Alternative types of positive displacement pumps, such as vane pumps or rotary lobe pumps, generate pressure-side pulsations through the displacement process, causing significant vibrations in the inlet of the temperature control circuit. Regardless of acoustic frequencies, the aim is to minimize vibrations in battery storage modules to prevent fatigue damage at the numerous contact and solder joints of a conductor structure between the individual battery cells.

[0012] In contrast, the rotary motion of screw spindles produces a relatively uniform pumping behavior. Therefore, the pump of the temperature control device according to the invention ensures lower noise levels for a battery storage module, particularly in conjunction with a cavity for housing battery cells in the temperature control device.

[0013] Although screw spindle pumps are known in the prior art, they are currently used in a different design and application.

[0014] Screw pumps feature a robust, dirt-resistant rotary lobe mechanism that eliminates the need for delicate components such as sliding gates or similar parts. Volumetric adjustment relative to a predetermined speed is not possible. Mechanically driven screw pumps are primarily known for their use in large-scale applications, such as oil pumps in stationary systems or marine engines, where they operate at relatively constant operating points.

[0015] In the field of vehicle fuel pumps, smaller, electrically driven screw pumps have recently become known. The electric drive of such fuel pumps is designed as a wet-running electric motor without a containment shell, so that both the rotor and the stator are in contact with the fuel.

[0016] US Patent 2018 / 0216614 A1 describes a screw pump intended for use as a fuel pump. A cover with an axial outlet is attached to the pump housing. The electric motor is housed in an outlet chamber of the cover and is subjected to a flow of fuel before exiting the outlet.

[0017] DE 10 2015 101 443 B3 describes a fuel pump with a housing in which an electric drive motor is coupled to a screw pump. The fuel flows through the drive motor before exiting the pressure-side outlet.

[0018] WO 2014 / 138519 A1 discloses an electric liquid pump of the screw spindle type. The liquid, which flows through an inlet and an outlet, also surrounds the motor. The liquid is specified as a fuel.

[0019] German patent DE 10 2017 210 771 A1 discloses an electrically driven screw pump used as a fuel delivery unit. A pump housing and an electric motor are enclosed in a casing. In the illustrated embodiment, which does not have a containment shell on the stator of the electric motor, the electrical components of the motor are in direct contact with the fuel within an outlet guide on the pressure side of the screw chamber.

[0020] However, the known screw-type fuel pumps are not suitable for use as pumps in the temperature control device of a battery storage module according to the invention. Unlike an oil-based fuel, a water-based temperature control medium or coolant would corrode the exposed components of the wet-running electric motor, such as the stator coil windings. In particular, the invention aims to provide a temperature control device for a battery storage module that significantly facilitates cost-effective mass production.

[0021] Furthermore, a temperature control device with the features of the preamble of claim 1 is known from the subsequently published WO 2020 / 164776 A1.

[0022] Finally, DE102018107139 A1 discloses a cooling device for a battery pack of an electric vehicle, wherein a rotary piston pump is used for the circulation of the cooling fluid.

[0023] The invention provides a temperature control device for a battery storage module with a screw spindle mechanism for conveying a temperature control medium. The invention further provides a dry-running electric motor for driving the spindle mechanism. The temperature control device is suitable for conveying a corrosive temperature control medium.

[0024] According to the invention, a driven screw spindle and a trailing screw spindle are floatingly mounted in the spindle housing by means of a radial clearance fit and are axially movable. This automatically creates an effective radial sealing gap to prevent leakage between the screw spindles and the spindle housing. An axial sealing gap forms independently of manufacturing tolerances. Maintaining a specific axial clearance at the opposite end of the screw spindles is not required. This significantly simplifies cost-effective series production.

[0025] Advantageous further developments of the invention are the subject of the dependent claims.

[0026] According to one aspect of the invention, the temperature control device can further comprise a plug-in coupling with one axial degree of freedom, which is arranged between a shaft of the electric motor and the driven screw spindle. By using a plug-in coupling that allows at least one axial play, the clearance fit to the floating bearing of the driven screw spindle is affected as little as possible. Furthermore, an interface for coupling a shaft from different electric motors is created, enabling a modular drive concept for the temperature control device.

[0027] According to one aspect of the invention, the temperature control device can further comprise a receiving housing that includes an open cavity and an inlet section as well as a return section of the temperature control circuit, which open into the open cavity. The spindle housing can be inserted into the open cavity from an axial end to a housing flange, and the temperature control circuit can be connected to the inlet and outlet openings of the spindle housing.

[0028] This design involves a structural integration between a pump housing and a housing component of the temperature control device. This eliminates the need for hose connections or fluid couplings at the interface between the pump and the inlet and return lines of the temperature control circuit, thus saving the corresponding installation space within the temperature control device.

[0029] The open cavity of the housing, which surrounds the spindle housing, serves as the pump's outlet chamber. This design of the housing for the temperature control device thus allows for 360° of freedom regarding the radial arrangement of the return path to the pump. This enables the selection of an arrangement optimized for the smallest possible installation space.

[0030] On one side, the pump features a pump head in the form of a spindle housing that can be inserted into a cavity, and on the other side, a motor housing located outside the cavity. Despite the integrated design, the use of electric motors of varying sizes is possible.

[0031] According to one aspect of the invention, a housing flange arranged between the spindle housing and the motor housing can have a bearing seat for a shaft bearing extending towards the side of the motor housing. This design allows the use of a single shaft bearing and contributes to a compact axial dimension of the pump in the temperature control device.

[0032] According to one aspect of the invention, the spindle housing can be delimited in the area of ​​the inlet opening by a key that is inserted through a radial mounting gap. By designing a key that can be simplified to a bearing shield with an inlet opening, the assembly and fitting of the screw spindles is simplified.

[0033] According to one aspect of the invention, an electric motor shaft can be supported by a shaft bearing with a plain bearing bushing, and the plain bearing bushing can be surrounded by a sealed lubricant filling. This design enables a compact and durable shaft support. The sealed lubrication of the plain bearing bushing resists being washed away or deposited by a temperature control medium. In contrast to oil-based fluids such as lubricating oils or fuels, contact between the plain bearing and a temperature control medium can impair the sliding properties of the shaft bearing. Furthermore, the sealed lubricant filling, together with the plain bearing gap of the plain bearing bushing, ensures a special sealing function.A good and durable sealing function is of high relevance for the service life of the pump and the operational reliability of the battery storage module to be temperature-controlled, especially when operating with higher delivery pressures on the one hand and using a dry-running electric motor on the other.

[0034] According to one aspect of the invention, power electronics can be arranged in the motor housing in thermal contact with the housing flange. The housing flange is in contact and heat exchange with the spindle housing and the receiving housing, through which the temperature control medium of the temperature control circuit flows. The arrangement of the power electronics in thermal contact with the housing flange provides an effective structure for dissipating waste heat from the electric motor's power electronics.

[0035] The invention is described below with reference to one embodiment and the accompanying drawing. Fig. 1 shows a schematic representation of the temperature control circuit as well as a sectional view of a screw spindle mechanism of a temperature control device for a battery storage module according to an embodiment of the invention.

[0036] For the purposes of this disclosure, the term "temperature control circuit" refers to a circulation circuit for a temperature control medium. The circulation medium can be a water-based coolant containing additives such as glycol or another antifreeze. The operation of the temperature control circuit is not limited to cooling. It can also provide a heating function using a heat source, for example, during the start-up phase of a system or when the ambient temperature is low.

[0037] The terms inlet section and return section of the temperature control circuit refer to the battery storage module being temperature-controlled. Accordingly, the inlet section of the temperature control circuit is connected to the pump outlet, and the return section is connected to the pump inlet.

[0038] A temperature control circuit can integrate multiple battery storage modules in series or in parallel. Furthermore, a temperature control circuit can connect multiple temperature control devices and multiple pumps.

[0039] For the purposes of this disclosure, the term "temperature source" refers to an atmosphere or convective airflow in the system environment, a cooling source containing a refrigerant, or a heat source such as an electric heating element. The respective temperature sources are in thermal contact with the temperature control medium in the temperature control circuit via a heat exchanger such as a finned radiator or the like.

[0040] For the purposes of this disclosure, the term screw pump refers to helical-geared rotary piston pumps with a thread pitch for displacing a pumped medium. Such pump types generally comprise a driven screw spindle and at least one further screw spindle that is driven along by an engagement of the gear teeth.

[0041] The temperature control device, which is in Fig. 1 As shown, a pump 1 is integrated within a temperature control circuit 50. The temperature control circuit 50 serves to regulate the temperature of a battery storage module 5, in particular to dissipate waste heat generated during charging or power dissipation by means of a temperature control medium pumped by the pump 1 via a heat exchanger (not shown). In the following application, the battery storage module 5 (not shown) is a traction battery for a battery electric vehicle. The temperature control circuit 50 has a plurality of small-cross-sectional channels that are in thermal contact with a plurality of battery cells of the battery storage module 5.

[0042] In the embodiment of the schematic representation from Fig. 1In a spindle housing 10 of the pump 1, a driven screw spindle 2a and a trailing screw spindle 2b are rotatably mounted in a spindle chamber 12 of the spindle housing 10. The cross-sectional contour of the spindle chamber 12 is formed by two bores in the spindle housing 10, the radii of which overlap to ensure engagement of the screw spindles 2a and 2b. An open side of the spindle chamber 12 is delimited by a key 18. The key 18 is formed as a flat end wall of the spindle chamber 12 and has an inlet opening 16 in the spindle housing 10. The key 18 is inserted into the spindle housing 10 through a mounting slot perpendicular to the screw spindles 2a and 2b.

[0043] The screw spindles 2a, 2b are floatingly mounted by a radial clearance fit with respect to the cross-sectional contour of the spindle chamber 12 and by an axial clearance fit of the spindle chamber 12. During pump operation, the spindles are pressed against the key 18 by the displacement process. The key 18 serves as a bearing shield for the axial sliding support of the end faces of the screw spindles 2a, 2b.

[0044] On the drive side of the screw spindles 2a, 2b shown on the right, there is a pressure side of the spindle chamber 12, which is connected to an outlet opening 17 of the spindle housing 10. On the other side of the screw spindles 2a, 2b, where the key 18 is located, there is a suction side of the spindle chamber 12. The suction side of the spindle chamber 12 is connected to the inlet opening 17 of the spindle housing 10.

[0045] The spindle housing 10, together with the screw spindles 2a, 2b, forms a pluggable pump head. This pump head is inserted into a receiving housing 15 of the temperature control device from an axial end of the spindle housing 10, towards which the inlet opening 16 is directed, to a housing flange 14, which is connected to the opposite axial end of the spindle housing 10. The receiving housing 15 is an integral component of the temperature control device, the pump 1, and the temperature control circuit 50. The receiving housing 15 can also be an integral component of a module housing of the battery storage module 5, in which the temperature control circuit 50 is continued in the form of integrated channels.

[0046] The receiving housing 15 has an open cavity 11 that accommodates the spindle housing 10 up to the housing flange 14. A return line 56 and a supply line 57 of the temperature control circuit 50 open into the cavity 11. The supply line 57 opens into a circumferential surface of the cavity 11. The cavity 11 surrounds the spindle housing 10 such that an annular portion of the cavity 11 overlaps the outlet opening 17 and the opening of the supply line 57. This free portion of the cavity 11 establishes a pressure-side connection between the spindle housing 10 and the temperature control circuit 50.

[0047] The return line 56 opens into a frontal bottom surface of the open cavity 11 and is located opposite the inlet opening 16 at the axial end of the inserted spindle housing 10. A sealing element 4 surrounds the opening of the return line 56 and the inlet opening 16, thus establishing a suction-side connection between the temperature control circuit 50 and the spindle housing 10. The sealing element 4 also surrounds a circumference of the spindle housing 10 in the area of ​​the mounting slot through which the key 18 is inserted. This seals any potential leakage along a keyway fit of the key 18. In the freestanding cavity 11, a sealing ring 19 is inserted in a groove-shaped radial space in front of the housing flange 14 to seal the pressure side of the pump 1 to the outside.

[0048] The driven screw spindle 2a is connected to an electric motor 3. On the pressure side of the spindle chamber 12, the spindle housing 10 has an opening for a shaft 32, which is driven by the electric motor 3. A motor housing 13, in which the electric motor 3 is arranged, is connected to the opposite side of the housing flange 14. An internal stator 33 of the electric motor 3 sits on a collar section of the housing flange 14. An external, cup-shaped rotor 35 rotates around the stator 33 and is connected to one end of the shaft 32. A bearing seat for a shaft bearing 31 is formed internally on the collar section of the housing flange 14. The shaft bearing 31 is a plain bearing, sealed at both axial ends and filled with a lubricant. The other end of the shaft 32 is coupled to the driven screw spindle 2a by means of a plug coupling 23, which allows axial play.

[0049] The motor housing 13 comprises a separate motor chamber in which the dry-running electric motor 3 and electronics, in particular power electronics 34 for switching the electrical power to the electric motor 3, are housed. The stator 33 comprises field coils that are controlled and supplied with electrical power by the power electronics 34. The stator 33 is in thermal contact with the circumferential surface of the collar section of the housing flange 14. In this way, waste heat from the field coils of the stator 33 is dissipated via the housing flange 14 to the receiving housing 15 and the spindle housing 10 and absorbed by the passing cooling circuit. Likewise, the power electronics 34 is arranged in thermal contact with the end face of the housing flange 14 in order to dissipate waste heat from the electronic components into a flow-through area of ​​the cooling circuit.

[0050] The following section describes the temperature control device in one direction of flow of the temperature control circuit 50 for temperature control of the battery storage module 5. A liquid medium is drawn from the return section 56 of the temperature control circuit 50 through the seal 4 and the inlet opening 16 of the spindle housing 10 into the spindle chamber 12 on the suction side. A rotary motion of the meshing screw profiles of the rotating screw spindles 2a, 2b creates a vacuum on the suction side of the spindle chamber 12 and a positive pressure on the opposite pressure side of the spindle chamber 12. The temperature control medium is conveyed by continuous displacement along the thread pitch of the meshing screw profiles and expelled from the spindle chamber 12 through the outlet opening 17 of the spindle housing 10.After the outlet opening 17, the temperature control medium flows via the cavity 11 into the inlet section 57 of the temperature control circuit 50 and to the battery storage module 5.

[0051] The temperature control medium then flows through a branch of channels in the temperature control circuit 50 within the battery storage module 5. These channels are formed in the receiving housing 15 of the temperature control device and are in thermal contact with the battery cells of the battery storage module 5. The temperature control medium then flows through a heat exchanger, transferring waste heat absorbed by the battery cells of the battery storage module 5 to a cooler medium, such as ambient air, and is drawn back into the pump 1. The flow through the battery storage module 5 and the heat exchanger can also occur in reverse within the temperature control circuit 50. Furthermore, the temperature control device 50 can additionally include a further temperature source, such as a heating element, through which the temperature control circuit 50 flows. Reference symbol list:

[0052] 1 Pump 2a Driven screw spindle 2b Followed screw spindle 3 Electric motor 4 Seal 5 Battery storage module 10 Spindle housing 11 Cavity 12 Spindle chamber 13 Motor housing 14 Housing flange 15 Mounting housing 16 Spindle housing inlet opening 17 Spindle housing outlet opening 18 Key 19 Sealing ring 23 Plug-in coupling 31 Shaft bearing 32 Shaft 33 Stator 34 Power electronics 35 Rotor 50 Temperature control circuit 56 Temperature control circuit return line 57 Temperature control circuit supply line

Claims

1. A temperature control device for a battery storage module (5), comprising: a temperature control circuit (50) configured to control the temperature of a plurality of battery cells in the battery storage module (5); wherein the temperature control circuit (50) carries a temperature control medium and comprises a plurality of channels which are in thermal contact with the battery cells; a heat exchanger which establishes thermal contact between the temperature control medium and a temperature control source; wherein the temperature control device comprises a pump (1) for circulating the temperature control circuit (50): a spindle housing (10) with an inlet opening (16) and an outlet opening (17); and at least one screw spindle (2a, 2b) rotatably received within the spindle housing (10) and coupled to the electric motor (3); wherein the electric motor (3) is designed as a dry-run motor and is arranged separately from the spindle housing (10) characterized in that a driven screw spindle (2a) and an entrained screw spindle (2b) are mounted in the spindle housing (10) in a floating manner by means of a radial clearance fit and are axially movable.

2. The temperature control device according to claim 1, further comprising a plug-in coupling (23) with one degree of axial freedom, which is arranged between a shaft (32) of the electric motor (3) and the driven screw spindle (2a).

3. The temperature control device according to one of the preceding claims, further comprising: a housing (15) comprising an open cavity (11) and a supply line (57) as well as a return line (56) of the temperature control circuit (50), which open into the open cavity (11); wherein the spindle housing (10) can be inserted into the open cavity (11) from one axial end to a housing flange (14), and the temperature control circuit (50) can be connected to the inlet opening (16) and the outlet opening (17) of the spindle housing (10).

4. The temperature control device according to one of the preceding claims, wherein a housing flange (14), which is arranged between the spindle housing (10) and the motor housing (13), comprises a bearing seat for a shaft bearing (31) which extends towards the side of the motor housing (13).

5. The temperature control device according to one of the preceding claims, wherein the spindle housing (10) is bounded in the region of the inlet opening (16) by a key (18) which is inserted through a radial assembly gap.

6. The temperature control device according to one of the preceding claims, wherein a shaft (32) of the electric motor (3) is supported by a shaft bearing (31) comprising a plain bearing bush, and the plain bearing bush is surrounded by a sealed lubricant filling.

7. The temperature control device according to one of the preceding claims, wherein a power electronics unit (34) is arranged within the motor housing (13) in thermal contact with a housing flange (14) which is in contact with the spindle housing (10).