Fluid pump

Abstract

To provide an improved or at least another embodiment for a general type fluid pump.SOLUTION: The present invention relates to a fluid pump (1) for a fuel cell system. The fluid pump (1) includes an impeller unit (2) including an impeller (4), an inlet side (2a) including a fluid inlet (5a), and an outlet side (2b) including a fluid outlet (5b). The fluid pump (1) further includes an electric motor (6). The fluid pump (1) also includes a guide flow path (23) for cooling fluid. The guide flow path (23) fluidally connects the inlet side (2a) and an outlet side (2b) via the impeller (4) and via the motor (6). According to the present invention, the fluid pump (1) is designed so that all of the surface in the guide flow path (23), where cooling fluid can be directly used, avoids any ions from being separated from the cooling fluid. The present invention relates to a fuel cell system including the fluid pump (1).SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a fluid pump for a fuel cell system comprising at least one fuel cell stack of several fuel cells according to the preamble of claim 1. The present invention also relates to a fuel cell system comprising the fluid pump. [Background technology]

[0002] Fluid pumps are already known from the prior art and usually comprise an impeller for conveying the fluid and an electric motor for driving the impeller. Fluid pumps can be used, for example, for cooling fuel cell systems in heavy goods vehicles. Fuel cell systems then usually have several fuel cell stacks, which contain several fuel cells. Thereby, the fuel cell stacks are cooled by the conveyed fluid, where, for the required cooling performance, the fluid is conveyed by several fluid pumps. Unfortunately, this requires a high installation space. When cooling the fuel cell stacks of a fuel cell system, there are also separate requirements regarding the fluid. The fluid should in particular be a dielectric and remain a dielectric. Summary of the Invention [Problem to be solved by the invention]

[0003] It is therefore an object of the present invention to provide an improved or at least an alternative embodiment for a fluid pump of the general type, in which the stated drawbacks are overcome, and also to provide a corresponding fuel cell system. [Means for solving the problem]

[0004] This object is solved according to the invention by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.

[0005] The invention is based on the general idea of ​​adapting a fluid pump used in a fuel cell system, in particular for use in heavy goods vehicles.

[0006] A fluid pump is provided for a fuel cell system comprising at least one fuel cell stack of several fuel cells. The fuel cell system is provided in particular for heavy goods vehicles. Thereby, the fluid pump comprises an impeller unit comprising an impeller for conveying a cooling fluid. Thereby, the impeller unit has an inlet side comprising a fluid inlet and an outlet side comprising a fluid outlet, said inlet side and outlet side being separated from each other by the impeller. The fluid pump further comprises an electric motor with a shaft rotating about a rotation axis, said shaft of the electric motor being drivably connected to the impeller of the impeller unit. Furthermore, the fluid pump comprises a guide channel for the cooling fluid comprising an impeller path and a motor path, the impeller path of the guide channel fluidically connecting the inlet side and the outlet side via the impeller, and the motor path of the guide channel fluidically connecting the inlet side and the outlet side via the motor. According to the invention, the fluid pump is designed such that all surfaces in the guide channel, where the cooling fluid may be directly used, do not separate any ions into the cooling fluid.

[0007] As mentioned above, the guide passage has an impeller passage that fluidically connects the inlet side and the outlet side via the impeller and a motor passage that fluidically connects the inlet side and the outlet side via the motor. The impeller passage and the motor passage are thereby offset from each other and fluidly connected to each other. The impeller passage is thereby led directly above the impeller of the impeller unit, so that the cooling fluid in the impeller passage can be transported from the inlet side to the outlet side by the impeller. The motor passage leads around the impeller of the impeller unit and connects the inlet side and the outlet side via the motor, in particular via the motor housing of the motor. The pressure difference between the inlet side and the outlet side can be used for the circulation of the cooling fluid in the motor passage. The motor passage can in particular contribute to the self-cooling of the motor. The motor passage can in particular be formed in the motor housing of the motor and can be fluidically separated from the current-conducting components of the motor. For this purpose, the motor housing can be formed with a double wall. The fluid pump can in particular be a so-called dry rotor with a jacket cooling section.

[0008] It goes without saying that the separation of ions into the cooling fluid cannot be completely excluded physically. However, the number of ions separated into the cooling fluid is so small that the impact on the physical quantity of the cooling fluid is negligible over longer times, especially over months. In other words, the fluid pump is designed so that all surfaces in the guide channels where the cooling fluid can be directly used reduce the release of ions into the cooling fluid. The term "surfaces that can be directly used" refers to surfaces that are in direct contact with the cooling fluid during the operation of the pump or have a perimeter through which the cooling fluid flows directly, respectively.

[0009] For this, the elements of the fluid pump, including the surfaces on which the cooling fluid can be directly applied, can on the one hand be made from a material with reduced ion emission or can be coated with a coating with reduced ion emission. The surfaces in the guide channels on which the cooling fluid can be directly applied can be formed, for example, by the impeller and / or the impeller housing that accommodates the impeller and / or the motor housing of the motor and / or at least one seal present in the fluid pump and / or the impeller housing that accommodates at least one bearing provided in the fluid pump. For example, the surfaces on which the cooling fluid can be directly applied can be passivated with aluminum oxide in at least some areas. The impeller can be made, for example, in one piece, preferably of polyphenylene sulfide. On the other hand, the cooling fluid cannot be directly applied to the surfaces of the elements of the fluid pump, causing high ion emission. For this, the guide channels in the fluid pump are accordingly guided around the elements mentioned, which can optionally be indirectly cooled. Thus, for example, the guide channels can surround the stator and rotor of the electric motor.

[0010] Thus, according to the invention, ions cannot be separated into the cooling fluid in the fluid pump and the release of ions into the cooling fluid can be controlled. That is why the function of the fuel cell system can be ensured and the service life of the fuel cell system can be increased. Expediently, the cooling fluid is dielectric or electrically non-conductive, respectively. Primarily, the cooling fluid is liquid. The cooling fluid can be, for example, an aqueous mixture, such as a water-glycol mixture. In the case of a further variant of the fluid pump, the motor can have a current-carrying group, which comprises a rotor connected rotationally fixedly to the shaft and a stator housing the rotor. The motor can have a motor housing, and the current-carrying group can be housed in the motor housing. The motor path of the guide channel can be formed in the motor housing and can be fluidically separated by the motor housing from the current-carrying group. For this purpose, the motor housing can be formed, for example, in a double-walled manner in at least some areas. The cooling fluid therefore does not flow around surfaces which would cause a high ion emission of the current carrying group, and ion emission or separation of ions into the cooling fluid can therefore be excluded. The motor path of the guide channels can be guided in the motor housing in such a way that the current carrying group is indirectly cooled with the cooling fluid and nevertheless sufficiently effectively. As already explained, the motor housing can be formed for this purpose in a double-walled manner at least in some areas.

[0011] The electric motor can have a motor housing, and the guide channel can advantageously be formed at least in some areas by a cooling fluid jacket formed in the motor housing. The current carrying motor group can also be indirectly cooled here by a cooling fluid. As already explained, the current carrying group can have a rotor connected in a rotationally fixed manner to the shaft and a stator.

[0012] The electric motor may have a motor housing and the impeller unit may have an impeller housing. Furthermore, the fluid pump may have a mechanical seal clamped in a sealing manner between the motor housing and the impeller housing. The mechanical seal may seal the fluid pump or the guide passage, respectively, against the outside. The mechanical seal may be made of SiC. Thus, the mechanical seal is free from any wear and therefore from ion release into the cooling fluid.

[0013] The fluid pump can have at least one bearing (preferably two bearings) for the rotating shaft, the at least one bearing being fluidically separated from the guide channel by the above-mentioned mechanical seal. By means of the mechanical seal, contact between the cooling fluid in the guide channel and the at least one bearing can be avoided, and thus the service life of the respective bearing can be increased. The at least one bearing can be made watertight. The bearing can therefore be particularly resistant to slight leakage of the mechanical seal. The bearing can be designed in particular for a protection class IP67. For the protection class IP67, the bearing must be firmly fixed upon submersion of the fluid pump.

[0014] Advantageously, the fluid pump can have an inverter for the electric motor. The inverter can thereby be arranged on a longitudinal end of the motor that is located opposite the impeller unit. The motor path of the guide channel can thereby be guided adjacent to the inverter in at least some areas, so that the inverter can be cooled by the cooling fluid conveyed by the impeller unit. The inverter can thereby be fluidically separated by the motor housing from the motor path of the guide channel or from the cooling fluid in the motor path of the guide channel, respectively, so that the electric components of the inverter can be indirectly cooled by the cooling fluid. The inverter can for example have a control board that includes several power semiconductors, for example IGBTs, which can then be cooled by the cooling fluid. To improve the cooling of the inverter, the motor path of the guide channel can be guided in a serpentine or labyrinth-like manner over the inverter.

[0015] Advantageously, the fluid pump can have an inverter for the electric motor, which can have a motor housing. Thereby, the inverter can be arranged in a heat-transferring manner on a longitudinal end of the motor located outside the bottom of the motor housing and facing the impeller unit. The motor path of the guide channel can be led to at least some areas of the bottom of the motor housing facing away from the inverter, so that the inverter can be cooled by the cooling fluid conveyed by the impeller unit. This allows the bottom to be aligned transversely to the rotation axis, and the electric components of the inverter can be fluidically separated from the motor path of the guide channel or from the cooling fluid in the guide channel, respectively. The electric components of the inverter (for example a control board including several power semiconductors) can then be indirectly cooled by the cooling fluid. Thereby, the motor path of the guide channel can be guided on the bottom in a serpentine or labyrinth-like manner.

[0016] A cover can be provided at the bottom facing away from the inverter to fluidly separate the guide channels at the bottom of the motor housing from the group of motors and to allow current to flow therethrough. A cover seal can be purposefully placed between the bottom and the cover to seal the motor paths of the guide channels to the outside. As already mentioned, the group of motors that can allow current to flow therethrough can comprise a rotor that rotates with the shaft and a stator.

[0017] As already mentioned, the fluid pump is provided for a fuel cell system. The fuel cell system can be designed or provided, respectively, in particular for heavy goods vehicles. Advantageously, the fluid pump can have a maximum power of 4000 W to 6000 W, preferably 4500 W, and / or a maximum output of 400 l / min to 700 l / min and / or a maximum pressure of 3 bar to 4 bar, preferably 3.5 bar, and / or a maximum speed of 5000 / min to 6,000 / min, preferably 5,400 / min and / or a maximum torque of 6.0 Nm to 8.0 Nm. The maximum parameters specified here refer to full load operation of the fluid pump. Advantageously, the electric motor can be operated with a DC voltage of 400 V to 860 V, which is converted by an inverter. The electric motor can in particular be a permanent magnet synchronous motor. Advantageously, the impeller can have a maximum efficiency of 60% to 70%, preferably 65%.

[0018] The invention also relates to a fuel cell system with at least one fuel cell stack of several fuel cells for heavy goods vehicles, whereby the fuel cell system comprises the above-mentioned fluid pump. The fuel cell system preferably comprises one single above-mentioned fluid pump. In particular, the fuel cell system does not comprise a further fluid pump provided for conveying a cooling fluid to the at least one fuel cell stack. In other words, the fluid pump is designed such that the cooling fluid for the entire fuel cell system can be conveyed by one single fluid pump. The fuel cell system can thereby comprise several (in particular two) fuel cell stacks. The cooling fluid for several fuel cell stacks can thereby be conveyed by one single fluid pump. To this end, the fluid pump can have the above-mentioned characteristics. To avoid repetition, reference is made at this point to the above remarks.

[0019] Further important features and advantages of the invention emerge from the dependent claims, from the drawings and from the corresponding figure descriptions based on the drawings.

[0020] It should be understood that the above features and characteristics described below can be used not only in specific combinations but also in other combinations or alone without departing from the scope of the present invention.

[0021] Preferred exemplary embodiments of the present invention are illustrated in the drawings and will be explained in more detail in the following description, where like reference numbers indicate identical, similar or functionally identical elements. [Brief description of the drawings]

[0022] In each case, broadly speaking: [Figure 1] 1 shows an exploded view of a fluid pump according to the present invention; [Diagram 2] 1 shows a cross-sectional view of a fluid pump according to the present invention; [Diagram 3] 1 shows different views of a fluid pump according to the invention; [Figure 4]1 shows different views of a fluid pump according to the invention; [Diagram 5] 1 shows different views of a fluid pump according to the invention; [Figure 6] 1 shows different views of a fluid pump according to the invention; [Figure 7] 1 shows different views of a fluid pump according to the invention; [Figure 8] 1 shows different views of a fluid pump according to the invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] FIG. 1 shows an exploded view of a fluid pump 1 according to the invention. The fluid pump 1 is provided or designed, respectively, for a fuel cell system comprising at least one fuel cell stack of several fuel cells. The fuel cell system can in particular be provided or designed, respectively, for heavy goods vehicles. The fluid pump 1 thereby comprises an impeller unit 2 with an impeller housing 3 and an impeller 4. The impeller 4 is made in one piece, preferably made of polyphenylene sulfide. Furthermore, the impeller unit 2 comprises an inlet side 2a (i.e. low pressure side) with a fluid inlet 5a and an outlet side 2b (i.e. high pressure side) with a fluid outlet 5b. The inlet side 2a and the outlet side 2b are separated from each other by the impeller 4 or are fluidly connected to each other. The fluid inlet 5a and the fluid outlet 5b are formed in the impeller housing 3.

[0024] Furthermore, the fluid pump 1 comprises an electric motor 6, which may in particular be a permanent magnet synchronous motor. Thereby, the motor 6 comprises a shaft 8 rotating about a rotation axis RA, a rotor 9 capable of carrying electric current and firmly connected to the shaft 8, and a group 7 comprising a stator 10 housing the rotor 9. The shaft 8 is drivably connected to the impeller 4. Here, the rotation axis RA corresponds to the longitudinal central axis of the fluid pump 1, and the motor 6 has two longitudinal ends 6a and 6b located opposite each other with respect to the rotation axis RA. The impeller unit 2 is arranged at the longitudinal end 6a of the motor 6.

[0025] The motor 6 further comprises a motor housing 11 consisting of a pot-shaped housing body 11a and a bottom part 11b aligned transversely to the rotation axis RA. The motor housing 11 further comprises a housing seal 12, which is arranged or clamped in a sealing manner between the housing body 11a and the bottom part 11b and seals the corresponding connection points, respectively, against the outside. The housing body 11a and the bottom part 11b are screwed together by several housing screws 13. The motor housing 11 also comprises a cover 11c, which closes the bottom part 11b on the stator side or the rotor side, respectively. A cover seal 14, which seals the corresponding connection points to the outside, is arranged or clamped in a sealing manner between the bottom part 11b and the cover 11c, respectively. The bottom part 11b and the cover 11c are screwed together by several cover screws 15.

[0026] The stator 10 is accommodated in a motor housing 11 in a rotationally fixed state, and a shaft 8 having a rotor 9 is accommodated in the motor housing 11 so as to rotate. To this end, the fluid pump 1 has two bearings 16a and 16b for accommodating the shaft 8 at the respective longitudinal ends 6a and 6b of the motor 6. Furthermore, an impeller seal 27 is arranged on the shaft 8 at the longitudinal end 6a.

[0027] The fluid pump 1 further comprises a mechanical seal 28, which is arranged or clamped in a sealing manner between the motor housing 11 and the impeller housing 3, respectively, and seals the corresponding connection points to the outside. The mechanical seal 28 is preferably made of SiC. The fluid pump 1 further comprises a U-shaped seal 21, which is also arranged or clamped in a sealing manner between the motor housing 11 and the impeller housing 3, respectively.

[0028] Furthermore, the fluid pump 1 comprises an inverter 17, which can be designed to convert a DC voltage of 400 V or more and 860 V or less for driving the motor 6. Thereby, the inverter 17 is arranged at the longitudinal end 6b of the motor 6 or on the opposite side to the impeller unit 2. This inverter 17 comprises a control board 18 and an inverter cover 19, the control board 18 being arranged between the bottom 11b of the motor housing 11 and the inverter cover 19. Furthermore, the inverter 17 comprises an inverter seal 20, which is arranged or clamped in a sealing manner between the bottom 11b and the inverter cover 19 and seals the corresponding connection points against the outside. The bottom 11b and the inverter cover 19 are screwed to each other by several inverter screws 22.

[0029] The fluid pump 1 is designed to convey a cooling fluid, preferably a liquid. For this purpose, the fluid pump 1 has a guide passage 23 with an impeller passage 23a and a motor passage 23b. The impeller passage 23a runs from the fluid inlet 5a on the inlet side 2a via the impeller 4 to the fluid outlet 5b on the outlet side 2b. The cooling fluid flows directly around the impeller 4 in the impeller passage 23a and is conveyed by the impeller 4 directly from the fluid inlet 5a to the fluid outlet 5b. The motor passage 23b of the guide passage 23 is here formed in several areas by a cooling fluid jacket 24 formed in the motor housing 11 and is led around the impeller 4 via the motor 6. The cooling fluid in the motor passage 23b does not flow directly around the impeller 4, but the flow of the motor passage 23b is caused by the pressure difference that exists between the fluid outlet 5b and the fluid inlet 5a.

[0030] Thereby, the cooling fluid jacket 24 comprises several (here seven) forward and return flow channels 25a and 25b in the housing body 11a and a serpentine or labyrinth-shaped connecting flow channel 26 between the bottom 11b and the cover 11c. Thereby, the forward flow channel 25a passes from the outlet side 2b through the housing body 11a into the serpentine or labyrinth-shaped connecting flow channel 26, respectively. The connecting flow channel 26 opens into the return flow channel 25b, which passes through the housing body 11a to the inlet side 2a. In the fluid pump 1, the cooling fluid is conveyed from the fluid inlet 5a at the inlet side 2a to the fluid outlet 5b at the outlet side 2b. From the outlet side 2b, part of the cooling fluid leaves the fluid pump 1 via the fluid outlet 5b and part of the cooling fluid flows into the cooling fluid jacket 24. From the cooling fluid jacket 24, the cooling fluid flows to the inlet side 2a, is conveyed again by the impeller 4 together with the cooling fluid to the outlet side 2b and enters the fluid pump via the fluid inlet 5a.

[0031] In the fluid pump 1, all surfaces in the guide channels 23 where the cooling fluid can be directly used do not separate any ions towards the cooling fluid. For this, the respective elements forming this surface at least in some areas can be made of a material with reduced ion emission or can be covered with a coating with reduced ion emission. Thus, the respective elements can be made, for example, of anodized aluminum. Furthermore, the cooling fluid does not flow directly into or around the groups 7 capable of carrying an electric current, so that ion emission into the cooling fluid is avoided in the fluid pump 1. The cooling fluid itself is a dielectric. The fluid pump 1 is therefore particularly suitable for cooling fuel cell systems.

[0032] The fuel cell system can be provided in particular for heavy goods vehicles. In this case, the fluid pump 1 can be designed such that one single fluid pump 1 is sufficient to cool the fuel cell system even if several fuel cells are stuck together. The fluid pump can therefore have a maximum power of 4000 W to 6000 W, preferably 4500 W, and / or a maximum output of 400 l / min to 700 l / min and / or a maximum pressure of 3 bar to 4 bar, preferably 3.5 bar, and / or a maximum speed of 5000 / min to 6,000 / min, preferably 5,400 / min and / or a maximum torque of 6.0 Nm to 8.0 Nm. The impeller 4 can have a maximum efficiency of 60% to 70%, preferably 65%.

[0033] Figure 2 shows a cross-sectional view of the fluid pump 1 according to the invention. In particular, the serpentine or labyrinth-like connecting passages 26 of the cooling fluid jacket 24 between the bottom 11b of the motor housing 11 and the cover 11c can be seen in Figure 2. Figures 3 to 8 show different views of the fluid pump 1. Figures 3 to 8 show the fluid pump 1 in an assembled state.

Claims

1. A fluid pump (1) comprising a fuel cell stack of at least one fuel cell, The fluid pump (1) comprises an impeller unit (2) comprising an impeller (4) for conveying a cooling fluid; The impeller unit (2) has an inlet side (2a) having a fluid inlet (5a) and an outlet side (2b) having a fluid outlet (5b), The inlet side (2a) and the outlet side (2b) are separated by the impeller (4), The fluid pump (1) comprises an electric motor (6) having a shaft (8) rotating about a rotation axis (RA), a shaft (8) of the electric motor (6) is drivingly connected to the impeller (4) of the impeller unit (2); The fluid pump (1) has a guide flow path (23) for a cooling fluid including an impeller path (23a) and a motor path (23b), an impeller path (23a) of the guide flow path (23) fluidly connects the inlet side (2a) and the outlet side (2b) via an impeller (4); a motor path (23b) of the guide channel (23) fluidly connects the inlet side (2a) and the outlet side (2b) via the electric motor (6); The fluid pump (1) is designed so that all surfaces within the guide channel (23) that can directly use the cooling fluid do not separate any ions into the cooling fluid. A fluid pump (1) characterized in that:

2. the surfaces onto which the cooling fluid can be directly applied are passivated with aluminum oxide in at least some areas; and / or The impeller (4) is made in one piece, preferably from polyphenylene sulfide.

2. The fluid pump according to claim 1.

3. The electric motor (6) has a group (7) consisting of a rotor (9) fixedly connected to the shaft (8) in rotational relation and a stator (10), The electric motor (6) has a motor housing (11), The group (7) capable of carrying current is housed in the motor housing (11), The motor path (23b) of the guide channel (23) is formed in the motor housing (11) and is fluidly separated by the motor housing (11) from the group (7) through which current can flow.

2. The fluid pump according to claim 1, wherein:

4. The electric motor (6) has a motor housing (11), At least a part of the motor path (23b) of the guide flow path (23) is formed by a cooling fluid jacket (24) formed in the motor housing (11).

2. The fluid pump according to claim 1.

5. The electric motor (6) has a motor housing (11), The impeller unit (2) has an impeller housing (3); and The fluid pump (1) has a mechanical seal (28), the mechanical seal (28) is hermetically clamped between the motor housing (11) and the impeller housing (3); 2. The fluid pump of claim 1 .

6. The mechanical seal (28) is made of SiC.

6. A fluid pump according to claim 5.

7. the fluid pump (1) has at least one bearing (16a, 16b) for the shaft (8), the at least one bearing (16a, 16b) being fluidly separated from the impeller path (23a) of the guide channel (23) by the mechanical seal (28); and / or the fluid pump (1) has at least one bearing (16a, 16b) for the shaft (8), the at least one bearing (16a, 16b) being watertight; 6. The fluid pump according to claim 5,

8. The fluid pump (1) has an inverter (17) for the electric motor (6), the inverter (17) being arranged at a longitudinal end (6b) of the electric motor (6) located opposite the impeller unit (2); and The motor path (23b) of the guide flow path (23) is guided adjacent to the inverter (17) in at least a certain region, preferably in a serpentine or labyrinth shape, so that the inverter (17) can be cooled by a cooling fluid, and the cooling fluid is transported by the impeller unit (2).

2. The fluid pump according to claim 1,

9. The fluid pump (1) has an inverter (17) for the electric motor (6), and the electric motor (6) has a motor housing (11); and the inverter (17) is arranged so as to be located outside the bottom (11b) of the motor housing (11), is aligned perpendicular to the rotation axis (RA), and is arranged so as to transfer heat to a longitudinal end (6b) of the electric motor (6) facing the impeller unit (2); a motor path (23b) of the guide flow passage (23) is guided in at least a portion thereof to a bottom (11b) of the motor housing (11) facing away from the inverter (17), preferably in a serpentine or labyrinth shape, so that the inverter (17) is cooled by the cooling fluid conveyed by the impeller unit (2); 2. The fluid pump of claim 1 .

10. The fluid pump (1) a maximum power of 4000 W to 6000 W, preferably 4500 W; and / or a maximum output of 400 l / min to 700 l / min, and / or a maximum pressure of 3 to 4 bar, preferably 3.5 bar, and / or a maximum speed of 5,000 min to 6,000 min, preferably 5,400 min, and / or A maximum torque of 6.0 Nm or more and 8.0 Nm or less, The electric motor (6) can be operated with a DC voltage between 400V and 860V, which is converted by an inverter (17); and / or the electric motor (6) is a permanent magnet synchronous motor, and / or The impeller (4) has a maximum efficiency of 60% to 70%, preferably 65%.

2. The fluid pump according to claim 1, wherein:

11. A fluid pump (1) according to any one of claims 1 to 10, A fuel cell system comprising at least one fuel cell stack of several fuel cells for a heavy goods vehicle.

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