DE102019211237A1 - Air supply device - Google Patents

Abstract

The invention relates to an air supply device (5) for a fuel cell, having at least one impeller (30) which is fastened to a shaft (40) with the aid of an axial clamping device (50). In order to improve the function of the air supply device (5), the axial tensioning device (50) two tensioning elements (51, 52), by means of which the impeller (30) is radially tensioned.

Description

The invention relates to an air supply device for a fuel cell, with at least one impeller which is fastened to a shaft with the aid of an axial tensioning device.

State of the art

From the American patent US 10,069,154 B2 an air supply device for a fuel cell is known, with a shaft; with a compressor wheel which is arranged in a compressor housing and which is fastened in one end of the shaft, the shaft having two shaft bearing sections designed as separate components and a magnet section arranged between the shaft bearing sections, forming a separate component and forming a rotor of an electric motor, wherein the shaft bearing sections and the magnet section are braced against one another via a tie rod.

Disclosure of the invention

The object of the invention is to functionally improve an air supply device for a fuel cell, with at least one impeller which is fastened to a shaft with the aid of an axial tensioning device.

In the case of an air supply device for a fuel cell, with at least one impeller, which is fastened to a shaft with the aid of an axial tensioning device, the object is achieved in that the axial tensioning device comprises two tensioning elements by which the impeller is radially tensioned. The air supply device is preferably a compressor with a housing in which an impeller is rotatably mounted about an axis of rotation. The impeller is driven, for example with the aid of an electric motor, in order to compress air supplied on the front of the impeller with the aid of suitable blades. Therefore the compressor is also referred to as an air compressor or air compressor. A fuel cell system preferably comprises a plurality of fuel cells, each of which comprises an anode and a cathode. The air supplied with the aid of the air supply device contains oxygen as an oxidizing agent, which is supplied to a cathode of the fuel cell. The fuel used is preferably hydrogen, which is stored, for example, in a pressurized gas reservoir and fed to an anode of the fuel cell. The impeller is rotatably mounted about an axis of rotation. The axis of rotation of the impeller defines an axial direction to which the term axial refers in relation to the tensioning device. Axial means in the direction or parallel to the axis of rotation of the impeller. Analog means radial transverse to the axis of rotation of the impeller. The fixing of the impeller on the shaft can be optimized by the radial pressure realized with the two clamping elements of the axial clamping device. The two clamping elements can particularly advantageously reduce an undesirable influence of different coefficients of thermal expansion. The impeller is made of an aluminum material, for example. The shaft is made of a steel material, for example. The tensioning elements are preferably formed from a metallic material, as is used for the production of conventional tensioning elements. This is, for example, a relatively solid metallic material that is preferably corrosion-resistant and does not deform too easily when it is braced. For this purpose, the material from which the tensioning elements are formed can be hardened.

A preferred embodiment of the air supply device is characterized in that the axial clamping device comprises a radially inner and a radially outer clamping element with conical surfaces, which are designed and arranged in such a way that the radially outer clamping element is pressed radially against the impeller when the axial clamping device is axially clamped becomes. When the axial clamping device is activated, an axial clamping force acting in the axial direction is applied to one of the clamping elements, preferably to the radially outer clamping element. The other clamping element, preferably the radially inner clamping element, is supported in the axial direction on an opposing surface, preferably on an end surface on an end of the shaft facing the impeller. As a result of the axial clamping force and the interaction of the clamping elements on their conical surfaces, the radially outer clamping element is pressed radially outward, so that the outer diameter of the radially outer clamping element increases. At the same time, the radially inner clamping element is clamped radially to the shaft. The desired radial tensioning of the impeller on the shaft is thereby achieved in a simple manner when the axial tensioning device is activated by applying the axial tensioning force.

Another preferred exemplary embodiment of the air supply device is characterized in that the impeller comprises a central tensioning recess which faces the shaft. The central clamping recess is designed, for example, as a central blind hole in the impeller. The two clamping elements can thus be easily mounted in the central clamping recess.

Another preferred embodiment of the air supply device is characterized in that the central clamping recess is arranged radially within an impeller section, which has a larger outer diameter than adjacent impeller sections. This ensures in a simple manner that the impeller has a sufficiently high strength in the area of the central clamping recess. The central clamping recess is particularly advantageously arranged radially inside the impeller section in which the impeller has the largest outer diameter.

Another preferred embodiment of the air supply device is characterized in that the impeller comprises a through hole which has a smaller inner diameter than the clamping recess. The through hole is preferably used to lead through a tensioning rod, which in turn serves to apply the axial tensioning force for activating the axial tensioning device. The tension rod also serves to center the impeller on the shaft. The tension rod is particularly advantageously designed as a multifunctional part which, if necessary, also serves to optimize the flow behavior of the air supplied to the impeller, which is compressed with the impeller.

Another preferred embodiment of the air supply device is characterized in that the axial tensioning device comprises a tensioning rod which extends in the axial direction through the tensioning elements and through the impeller into a central recess of the shaft. The two clamping elements are preferably arranged in the radial direction between the clamping rod and the impeller in the clamping recess of the impeller. The tension rod is used advantageously for fastening, in particular bracing, and for centering the impeller on the shaft.

Another preferred embodiment of the air supply device is characterized in that the tensioning rod has at least one centering collar on which the impeller is centered. For this purpose, the tension rod can also have two or more centering collars. At least one centering collar can be arranged radially inside at least one of the clamping elements. Depending on the design, however, two centering collars spaced apart from one another in the axial direction can also be arranged outside the clamping recess, for example in the previously described through hole of the impeller.

Another preferred exemplary embodiment of the air supply device is characterized in that the tension rod has a head at one end. The head is advantageously used to apply the axial clamping force for activating the axial clamping device to the clamping element with a suitable tool. For this purpose, the head is designed as a hemisphere, for example. However, the head can also have at least one tool engagement surface or mirror surface which enables a torque to be applied to the clamping rod via the head when this is screwed, for example, with one end into a corresponding end of the shaft. For this purpose, the head can also be equipped with a hexagon socket.

Another preferred exemplary embodiment of the air supply device is characterized in that one end of the tension rod is fixed in the shaft. One end of the tension rod can, for example, be pressed or screwed into the shaft. For this purpose, the shaft is advantageously equipped with a central recess, the inner diameter of which is matched to the outer diameter of the end of the tension rod to represent a press fit. The end of the tie rod and the central recess of the shaft can also be equipped with complementary threaded sections.

Another preferred embodiment of the air supply device is characterized in that the clamping rod has a clamping ring disk which is clamped in the axial direction against the outer clamping element, the radially inner clamping element being supported in the axial direction on the shaft. The clamping ring disc can be designed as a separate component. Then the clamping ring disc can be supported in the axial direction, for example on a suitable shaft collar. The clamping ring disk can also be connected in one piece to the shaft if the clamping ring disk is designed as a collar on the shaft, so to speak. The clamping ring washer as a separate component can, however, also be supported on a suitable shaft shoulder.

The invention optionally also relates to a method for assembling, in particular fastening, an impeller on a shaft of an air supply device described above.

The invention also relates to a tensioning element, a shaft and / or an impeller for an air supply device described above. The parts mentioned can be traded separately.

The invention optionally also relates to a fuel cell system with an air supply device described above.

Further advantages, features and details of the invention emerge from the following description, in which various exemplary embodiments are described in detail with reference to the drawing.

Figure list

• 1 eine Luftzuführvorrichtung für eine Brennstoffzelle, mit einem Laufrad, das mit Hilfe einer axialen Spanneinrichtung, die zwei Spannelemente umfasst, an einer Welle befestigt ist, im Längsschnitt;
• 2a einen vergrößerten Ausschnitt aus 1 mit einer Spannringscheibe;
• 2b einen weiteren vergrößerten Ausschnitt aus 1 mit einem Spannstangenkopf, der einen Innensechskant umfasst;
• 3 einen weiteren vergrößerten Ausschnitt aus 1 mit zwei Ausführungsvarianten zur Festlegung eines Spannstangenendes in der Welle; und
• 4 eine schematische Darstellung eines Brennstoffzellensystems mit einer Luftzuführvorrichtung, die als Luftverdichter ausgeführt ist.

Show it:

• 1 an air supply device for a fuel cell, with an impeller which is fastened to a shaft with the aid of an axial clamping device which comprises two clamping elements, in longitudinal section;
• 2a an enlarged section 1 with a tension washer;
• 2 B another enlarged section 1 with a tie rod head which comprises a hexagon socket;
• 3 another enlarged section 1 with two design variants for fixing a tie rod end in the shaft; and
• 4th a schematic representation of a fuel cell system with an air supply device, which is designed as an air compressor.

Description of the exemplary embodiments

In 4th is a fuel cell system 1 shown schematically. Fuel cell systems are known per se, for example from the German Offenlegungsschrift DE 10 2012 224 052 A1 . The fuel cell system 1 includes a fuel cell 3 which is only indicated by a dashed rectangle. The fuel cell 3 includes at least one stack 2 , which is shown alternatively with a valve symbol.

By an arrow 4th an air mass flow is indicated, which is via an air supply device designed as an air compressor 5 the fuel cell 3 is fed. By an arrow 6 is a compressed air mass flow 6 indicated, from which a cooling air mass flow 7th is branched off. The cooling air mass flow 7th is also only indicated by an arrow and is part of a cooling air path 19th over which the air compressor 5 Cooling air is supplied.

The one via the cooling air path 19th supplied cooling air is used, for example, to cool air bearings with which a shaft of the air compressor 5 is rotatably mounted. The cooling air mass flow 7th represents a loss in the compressed air mass flow 6 because the branched cooling air mass flow 7th no longer in the stack 2 the fuel cell 3 is available.

Since the cooling air mass flow 7th via the air compressor 5 is provided for internal cooling, energy, in particular electrical energy, is necessary to generate it. This energy has a negative effect on the overall efficiency of an electric drive machine of a motor vehicle that is powered by the fuel cell system 1 is driven.

The remaining air mass flow 6 is via an air supply line 8th the fuel cell 3 fed. The fuel cell 3 is a galvanic cell which converts the chemical reaction energy of a fuel supplied via a fuel supply line (not shown) and an oxidizing agent into electrical energy.

The oxidizing agent is the air coming through the air supply line 8th the fuel cell 3 is fed. The fuel can preferably be hydrogen or methane or methanol. Accordingly, water vapor and carbon dioxide are produced as exhaust gas. The exhaust gas is in the form of an exhaust gas mass flow 10 via an exhaust pipe 9 led away as if by an arrow 10 is indicated.

The exhaust gas mass flow 10 is via an exhaust turbine 11 to an exhaust outlet 12 dissipated, which is indicated by an arrow. The air compressor 5 is in the air supply line 8th arranged. The exhaust turbine 11 is in the exhaust pipe 9 arranged. The air compressor 5 and the exhaust turbine 11 are mechanically connected via a shaft.

The shaft is by an electric motor 14th electrically driven. The exhaust turbine 11 serves to support the electric motor 14th when driving the air compressor 5 . The air compressor 5 who have favourited the exhaust turbine 11 , the shaft and the electric motor 14th together form a turbo compressor 15th , which is also known as a turbo machine.

The fuel cell system 1 also includes a bypass line 13 , in which a bypass valve 16 is arranged. Via the bypass line 13 with the bypass valve 16 can be a bypass air mass flow 17th for reducing the pressure in the air supply line 8th bypassing the stack 2 the fuel cell 3 into the exhaust pipe 9 be discharged. This is advantageous, for example, to reduce the pressure in the air supply line 8th the fuel cell 3 to effect supplied air mass flow.

The fuel cell system 1 further comprises an intercooler 18th , which is indicated by a dashed rectangle. The intercooler 18th serves to control the compressed air mass flow 6 to cool before the cooling air mass flow 7th via the cooling air path 19th is branched off.

The fuel cell system 1 is with a scheme 20th equipped with which the branched cooling air mass flow 7th on the cooling air requirement of the turbo compressor 15th is regulated. By regulating the cooling air mass flow 7th to the needs of the turbo compressor 15th , which is also called Turbomachine or referred to as a machine for short, the branched off cooling air mass flow 7th be kept low. As a result, the efficiency of a motor vehicle, its prime mover via the fuel cell system 1 driven, be increased.

In 1 is an air supply device designed as an air compressor 5 , in the 4th is only indicated symbolically, in longitudinal section with an impeller 30th and a wave 40 but shown without housing. The impeller 30th is with the help of an axial clamping device 50 on the shaft 40 attached. The impeller shown simplified and cut off from the outside 30th comprises three impeller sections indicated by double arrows 31 , 32 , 33 in which the impeller 30th has different sized outer diameters. In the impeller section 32 has the impeller 30th its largest outside diameter.

Radially within and overlapping in the axial direction to the impeller section 32 includes the impeller 30th a central clamping recess 35 . The central clamping recess 35 has the shape of a straight circular cylinder that becomes a shaft 40 is open. At her the wave 40 the opposite end becomes the central clamping recess 35 of a paragraph 34 limited. In the center of the paragraph 34 opens into a central through hole 36 running through the impeller 30th extends therethrough into the central clamping recess 35 .

By arrows 37 and 38 is in 1 indicated that in the longitudinal sectional view of 1 at the same time two different embodiments of the axial clamping device 50 are shown. The arrow 37 corresponds to a first embodiment of the axial tensioning device 50 . The arrow 38 corresponds to a second embodiment of the axial tensioning device 50 .

The wave 40 is designed as a hollow shaft and has the impeller on its 30th facing end a central recess 44 on. The central recess 44 is designed as a hole, for example. In the central recess 44 is an end 58 a tie rod 57 attached.

The tie rod 57 is part of the axial clamping device 50 and serves to two clamping elements 51 , 52 the axial clamping device 50 to brace against each other so that the impeller 30th is braced radially.

The clamping element 51 is designed as a radially inner clamping element and on the clamping rod 57 arranged. The radially inner clamping element faces radially on the outside 51 a conical surface 53 on. On the cone surface 53 lies a conical surface 54 on, the radially inside on the radially outer clamping element 52 is trained.

The tie rod 57 extends through the two clamping elements 51 , 52 through which in turn in the clamping recess 35 of the impeller 30th are arranged. With the help of the two clamping elements 51 , 52 becomes a radial pressure in the central clamping recess 35 of the impeller 30th generated. In this way, the influence of different coefficients of thermal expansion of the materials that make up the impeller can be reduced 30th and the wave 40 are formed.

In 1 below is shown that the tie rod 57 with their end 58 by pressing 61 in the central recess 44 the wave 40 can be attached. The attachment of the tie rod end 58 in the central recess 44 the wave 40 but can also be done with an external thread 62 done with a complementary internal thread in the central recess 44 the wave 40 cooperates.

The claimed version of the axial clamping device 50 with the two clamping elements 51 and 52 provides, among other things, the advantage that a clamping nut usually used in axial clamping devices can be omitted.

The tie rod 57 points at her the shaft 40 remote end a head 60 on. The head 60 the tie rod 57 protrudes in 1 left out of the central through hole 36 of the impeller 30th out. The head 60 the tie rod 57 is in 1 designed as a hemisphere. In the embodiment indicated by the arrow 38 it is enough if the head 60 the shape of a hemisphere 63 having.

The in 1 by the arrow 37 indicated embodiment, it is indicated that the head 60 also with a tool contact surface 64 or mirror surface can be equipped. This is how applying torque to screw in the tension rod 57 with the external thread 62 in the central recess 44 the wave 40 simplified.

In 2 B is shown that the head 60 the tie rod 57 a hexagon socket for the same purpose 69 may include.

The through the axial clamping device 50 The radial pressure produced occurs when the clamping elements are axially braced 51 , 52 by an axial displacement of the tension rod 57 in the center of the clamping elements 51 , 52 . The tie rod is used for this 57 at the same time to center the impeller 30th on the shaft or on the shaft 40 . Therefore, the Tie rod 57 also as a centering and tensioning rod 57 are designated.

The axial clamping force is when the axial clamping device is activated 50 from the tie rod 57 for example via an in 1 downward protruding collar 45 on the radially outer clamping element 52 transfer. In 1 it is indicated above that the same function of a tension ring disc 59 can be exercised.

In 2a it is indicated that the clamping ring washer 59 for example via a covenant 66 that on the tie rod 57 is formed axially on the tie rod 57 can be supported. About the federal government 66 becomes the axial clamping force for activating the axial clamping device 50 on the tension ring 59 transfer.

For centering the impeller 30th on or on the wave 40 serve for example centering collars 41 , 42 , 43 . The centering collars 41 , 42 are on the tie rod 57 formed and spaced from each other in the axial direction in the through hole 36 of the impeller 30th arranged. The centering collar 43 is also on the tie rod 57 trained, but in contrast to the centering collars 41 , 42 is the centering collar 43 in the radially inner clamping element 51 arranged.

The radial tension or compression of the clamping elements 51 , 52 in the impeller 30th on the tie rod 57 provides the advantage, among other things, that the influence of the different thermal expansions is minimized because the diameter of the impeller changes 30th in the central clamping recess 35 changes little when the axial tensioner 50 is activated. A change in length of the impeller, which is preferably formed from an aluminum material 30th in the axial direction has little or no influence on the pressure, since the length of the impeller 30th is not in the force flow of the radial fixation.

In 3 is based on an enlarged section 1 indicated that the end 58 the tie rod 57 also with the help of a guide section 71 in the central recess 44 the wave 40 can be performed to center the impeller. The attachment of the end 58 the tie rod 57 takes place through a guide section 71 adjacent thread section 72 .

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102012224052 A1 [0019]

Claims (10)

Air supply device (5) for a fuel cell (3), with at least one impeller (30) which is fastened to a shaft (40) with the aid of an axial clamping device (50), characterized in that the axial clamping device (50) has two clamping elements ( 51, 52), through which the impeller (30) is radially braced. Air supply device according to Claim 1 , characterized in that the axial clamping device (50) comprises a radially inner (51) and a radially outer (52) clamping element with conical surfaces (53,54) which are designed and arranged so that the radially outer clamping element (52) radially is pressed against the impeller (30) when the axial clamping device (50) is axially clamped. Air supply device according to one of the preceding claims, characterized in that the impeller (30) comprises a central clamping recess (35) which faces the shaft (40). Air supply device according to Claim 3 , characterized in that the central clamping recess (35) is arranged radially inside an impeller section (32) which has a larger outer diameter than adjacent impeller sections (31, 33). Air supply device according to Claim 3 or 4th , characterized in that the impeller (30) comprises a through hole (36) which has a smaller inner diameter than the clamping recess (35). Air supply device according to one of the preceding claims, characterized in that the axial tensioning device (50) comprises a tensioning rod (57) which extends in the axial direction through the tensioning elements (51, 52) and through the impeller (30) into a central recess ( 41) of the shaft (40) extends into it. Air supply device according to Claim 6 , characterized in that the tension rod (57) has at least one centering collar (41, 42, 43) on which the impeller (30) is centered. Air supply device according to Claim 6 or 7th , characterized in that the tension rod (57) is fixed with one end (58) in the shaft (40). Air supply device according to one of the Claims 6 to 8th , characterized in that the clamping rod (57) has a clamping ring disc (59) which is clamped in the axial direction against the outer clamping element (52), the radially inner clamping element (51) being supported in the axial direction on the shaft (40) . Clamping element (51, 52), shaft (40) and / or impeller (30) for an air supply device (5) according to one of the preceding claims.

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