DE102019216860A1 - Axial flux machine for an electrical processing device and electrical processing device with an axial flux machine - Google Patents

Abstract

The invention relates to an axial flux machine (10), in particular a one-sided axial flux motor, for an electrical machining device (34), with a machine shaft (12), in particular a motor shaft, a disk-shaped stator (20) and a machine shaft (12) in the axial direction (A) ) adjacent to the stator (20) arranged disc-shaped rotor (14), wherein the stator (20) is designed as a winding carrier (22) for at least one stator winding (24) and the rotor (14) non-rotatably connected to the machine shaft (12) relative to the The stator (20) can be set in a rotary movement. It is proposed that the stator (20) has a plurality of stator teeth (44) each with a single tooth winding (46) of the stator winding (24), the stator winding (24) as a triangular parallel connection (48) of the single tooth windings ( 46) is formed. The invention also relates to an electrical machining device (34) with an axial flow machine (10) according to the invention.

Description

The invention relates to an axial flux machine, in particular a one-sided axial flux motor, for an electrical machining device and an electrical machining device with an axial flux machine according to the preamble of the independent claims.

State of the art

Axial flux machines have the advantage over conventional electrical machines with a radial flow direction that they are very efficient and have a significantly reduced overall length. In addition, a higher torque or power density can be achieved with the same outer diameter. These improvements are due, among other things, to a larger air gap area with a comparable construction volume. Thanks to the lower iron volume of the rotating components, there is also a higher degree of efficiency over a larger speed range.

The construction of a stator of an axial flux machine is relatively complex due to the required 3-D magnetic flux guidance. The grooves in the laminated core usually have to be punched out prior to the winding process of the stator winding. In addition, the individual sheets result in disadvantages such that the pole pieces only protrude tangentially and that the stator teeth with the pronounced pole pieces cannot be wound externally, which results in a low fill factor of the stator winding and a correspondingly reduced degree of efficiency.

From the DE 10 2015 223 766 A1 an axial flow machine with bent and wound laminated cores is known as the winding carrier. The stator of the axial flux machine has a sintered support structure made of soft magnetic material and an insert designed as a laminated core. The insert is connected to the support structure via a form fit and / or force fit and at least partially forms a pole piece of the axial flow machine. The laminated core is formed by means of individual, stacked layers of single metal sheets, which consist of a soft iron. The individual sheets are electrically connected to one another in an insulated manner with respect to the respectively adjacent sheet.

The individual tooth windings of the stator winding of axial flux machines for electrical processing devices are usually operated in a star connection. Due to the higher internal resistance of the axial flow machine, this leads to a loss of efficiency, which is disadvantageous in particular in battery-operated electrical machining devices because of the shorter operating time on the one hand and the reduced torque on the other.

It is therefore the object of the invention to provide an axial flux machine that is more power-efficient than the prior art, in particular for use in electrical machining devices.

Advantages of the invention

The invention relates to an axial flux machine, in particular a one-sided axial flux motor, for an electrical machining device, with a machine shaft, in particular a motor shaft, a disk-shaped stator and a disk-shaped rotor arranged in the axial direction of the machine shaft adjacent to the stator, the stator being designed as a winding carrier for at least one stator winding and the rotor, which is non-rotatably connected to the machine shaft, can be set in rotary motion relative to the stator.

To solve the problem, it is provided that the stator has a plurality of stator teeth, each with a single tooth winding of the stator winding, the stator winding being designed as a triangular parallel connection of the single tooth windings. Due to the delta connection of the individual tooth windings, the entire supply voltage drops across each individual tooth winding. This requires an increase in the number of turns of each individual tooth winding in order to achieve a specifically required speed of the axial flux machine. By connecting individual single-tooth windings in parallel, their winding wire diameter can be increased and, with particular advantage, their internal resistance can be reduced. This results in a higher performance of the axial flow machine and consequently also of the electrical machining device compared to a star connection.

The invention therefore also relates to an electrical processing device, in particular an electric machine tool, with an axial flux machine according to the invention, in particular an axial flux motor according to the invention.

In the context of the invention, an electrical processing device is to be understood as meaning, inter alia, battery-powered or mains-operated electric machine tools for processing workpieces using an electrically driven insert tool. The electrical processing device can be designed both as a handheld electrical tool and as a stationary electrical machine tool. Typical power tools in this context are hand or standing drills, screwdrivers, impact drills, rotary hammers, demolition hammers, planes Angle grinders, orbital grinders, polishing machines or the like. Motor-driven gardening equipment such as lawn mowers, lawn trimmers, pruning saws or the like can also be used as electrical processing equipment. Furthermore, the invention can be applied to axial flow machines in household and kitchen appliances, such as washing machines, dryers, vacuum cleaners, mixers, etc.

The term axial flux machine can include both an axial flux motor and an axial flux generator for converting mechanical into electrical energy. An axial flux machine is also to be understood as an axial flux motor that is used at least temporarily for recuperation from mechanical to electrical energy, as can be the case, for example, with electrodynamic braking of an axial flux motor.

Embodiments

drawing

The invention is illustrated below with reference to 1 to 10 explained by way of example, the same reference numerals in the figures indicating the same components with the same mode of operation.

Figure list

• 1 : a section through an axial flux machine according to the invention in the form of a one-sided axial flux motor in a first embodiment,
• 2 : a schematic view of a further embodiment of a stator of the axial flux machine according to the invention,
• 3 : an exploded view of the stator 2 in a schematic view without stator winding,
• 4th : a schematic view of a section of the stator according to the invention in a further embodiment,
• 5 : a schematic sectional view of a rotor of the axial flow machine according to the invention,
• 6th : a schematic view of a housing of the axial flow machine according to the invention,
• 7th : Another schematic view of the empty housing of the axial flow machine according to the invention 6th ,
• 8th : a schematic view of a further embodiment of the cooling air duct within the axial flow machine according to the invention in a section,
• 9 : two embodiments of triangular parallel connections of the individual tooth windings of a stator winding of the axial flux machine according to the invention and
• 10 : an electrical processing device, in particular an electric machine tool in the form of a hammer drill, with an axial flow machine according to the invention.

Description of the exemplary embodiments

In 1 is a first embodiment of an axial flow machine according to the invention 10 shown in a section. The axial flow machine 10 can equally be designed as an axial flux motor or as an axial flux generator. On a machine shaft 12th the axial flow machine 10 is non-rotatable with the machine shaft 12th a disc-shaped rotor 14th arranged. The rotor 14th is as a bleached ring 16 made of soft magnetic iron and carries an alternately magnetized magnetic ring 18th , to which referring to 5 will be discussed in more detail. Because the rotor 14th however, as a rule, it is not exposed to an alternating field and thus the risk of eddy current losses is relatively low, the rotor can 14th alternatively also consist of non-soft magnetic materials such as iron or of a soft magnetic steel with a low carbon content. In the axial direction A. the motor shaft 12th is located adjacent to the rotor 14th or to the magnetic ring 18th also a disk-shaped stator 20th that acts as a winding carrier 22nd for at least one stator winding 24 (see. 2 ) is formed and a first stator yoke 26th has, as the magnetic return of the through the stator winding 24 and the magnetic ring 18th resulting magnetic field is used. Relative to the stator 20th or the stator winding 24 is the rotor 14th over the motor shaft 12th can be set in a rotary motion. To do this is the motor shaft 12th on the one hand via one in the stator yoke 26th integrated first warehouse 28 , for example as a fixed bearing 30th is formed, and on the other hand via a in a housing 32 an electrical processing device 34 (see. 10 ) added second camp 36 , for example as a floating bearing 38 is formed, rotatably mounted. The first and the second camp 28 , 36 are preferably designed as ball bearings. The first camp 28 is directly in the winding carrier 22nd and / or in the first stator yoke 26th integrated. For example, it can be pressed in or injected. Because one-sided axial flow machines in particular have a very high tensile force in the axial direction A. the machine shaft 12th in the air gap between the rotor 14th and stator 20th can have this as a fixed bearing 30th trained first camp 28 in the first stator yoke 26th be intercepted. Thus it is not necessary to pass the axial force through the housing 32 of the electrical processing device 34 and / or by a housing of the Axial flux machine (cf. 6th and 7th ) to record.

For cooling the axial flow machine 10 is non-rotatable on the machine shaft 12th a fan wheel 40 arranged, the cooling air through the axial flow machine 10 transported. The fan impeller also sucks 40 the cooling air preferably radially to it then axially through the axial flow machine 10 to transport.

2 shows a schematic view of a further embodiment of the disk-shaped stator 20th the axial flow machine according to the invention 10 . The stator 20th essentially comprises the first stator yoke 26th , one in the axial direction A. the machine shaft 12th second stator yoke arranged adjacent thereto 42 and the one to the second stator yoke 42 in the axial direction A. the machine shaft 12th adjacently arranged winding support 22nd . The winding carrier 22nd consists essentially of a plurality of, in particular six, the stator winding 24 bearing stator teeth 44 , with each stator tooth 44 a single tooth winding 46 the stator winding 24 assigned. The single tooth windings 46 are related to 9a in a triangle-parallel connection 48 electrically connected to each other.

The stator teeth 44 and the first stator yoke 26th of the stator 20th are made of composite materials (Soft Magnetic Composites - SMC) and are permanently connected to one another, in particular glued, by a joining process. SMC materials consist of high-purity iron powder with a special surface coating on each individual particle. This electrically insulating surface ensures a high electrical resistance even after pressing and heat treatment, which in turn minimizes or prevents eddy current losses. With particular advantage over prior art axial flux machines, an axial flux machine that is extremely resistant to mechanical loads and at the same time very powerful and efficient, or a high-torque axial flux motor, can be provided. The joining of the stator teeth 44 with the first stator yoke 26th enables the winding support to be wound externally 22nd by applying the stator winding 24 or the individual tooth windings 46 on the stator teeth 44 during the joining process. This gives the stator winding a high fill factor 24 achievable.

The second stator yoke 42 of the rotor 20th exists in contrast to the first stator yoke 26th made of soft magnetic iron and is available as a sheet metal package 48 (see. 3 ) with a plurality, in particular six, grooves distributed over its outer circumference 50 designed to accommodate the composite materials. The number of grooves 50 corresponds to the number of stator teeth 44 . The second stator yoke 42 thus stabilizes the stator 20th under high mechanical stress and guarantees improved magnetic flux guidance due to its high permeability. The grooving of the laminated core 48 not only causes better absorption of the composite materials and thus greater stability of the stator 20th , but also ensures optimized guidance of the essentially through the stator winding 24 caused eddy currents.

According to 3 has the second stator yoke 42 to accommodate the stator teeth 44 circular segment-shaped recesses arranged in a ring 52 on, with each groove 50 the outer circumference of the second stator yoke 42 up to the respective radially inner recess 52 interrupts. Every stator tooth 44 is through a circular segment-shaped tooth flange 54 , the the circular segment-shaped recess 52 of the second stator yoke 42 reaches through, and one the tooth flange 54 encompassing, circular segment-shaped carrier frame 56 with a circumferential U-profile 58 to accommodate the stator winding 24 or the individual tooth windings 46 educated. Tooth flange 54 and support frame 56 are permanently connected to each other via a joining process, in particular glued.

4th shows a schematic view of a section of the stator according to the invention 20th in a further embodiment. This is where the stator teeth 44 or their tooth flanges 54 (see. 3 ) through the recesses 52 of the second stator yoke 42 passed through and with the first stator yoke 26th permanently connected by laser welding. Each roughly in the middle of the first stator yoke 26th resting surface of a stator tooth 44 is a hole 60 in the first stator yoke 26th provided through which the stator tooth 44 by means of laser welding with the first stator yoke 26th is connectable. For permanent connection of the first stator yoke 26th and the respective stator tooth 44 a weld extends over the complete circumference of the bore 60 . Alternatively, however, it can also be provided that the weld seam extends only selectively over the circumference of the bore 60 extends. By welding in the middle of each stator tooth 44 the guidance of the magnetic flux is only slightly influenced and there is a high level of plane parallelism of the stator teeth 44 to reach the radial air gap between them. By avoiding adhesive bonding, an adhesive gap between the stator tooth can be effectively created 44 and first stator yoke 26th can be avoided and there is no fixation of the stator tooth 44 and first stator yoke 26th required during the hardening of the bond. Regarding 1 it is alternatively also conceivable to use the second stator yoke 42 to do without and instead use that as a laminated ring 16 first stator yoke made of soft magnetic iron 26th directly with the composite stator teeth 44 to connect, in particular by means of the bore 60 in the first stator yoke 42 to weld.

In 5 is a schematic view of the rotor 14th the axial flow machine according to the invention 10 shown in section. The rotor 14th is as a bleached ring 16 made of magnetically soft iron. He also wears an alternately polarized magnetic ring 18th , the one with the stator winding 24 of the stator 20th cooperates to the rotor in engine operation 14th to set in a rotary movement or a voltage in the stator winding in generator mode 24 to induce. The magnets of the magnetic ring, not shown in detail 18th are designed in the shape of a segment of a circle that their surfaces largely coincide with the segment of a circle-shaped stator teeth 44 cover in order to achieve an optimal magnetic flux in connection with a high torque. Instead of an alternately polarized magnetic ring 18th Alternatively, a ring with embedded individual magnets is also conceivable. As mentioned earlier, the rotor is 14th usually not exposed to an alternating field, so that there are no or only very low eddy current losses. Therefore, the rotor 14 of the axial flow machine 10 alternatively also consist of a non-soft magnetic material.

In a preferred embodiment of the invention, the sheet metal ring 16 of the rotor 14th than a rotor yoke 62 designed either with a bidirectional fan 40 is permanently connected by a joining process, in particular glued, or that itself as a bidirectional fan 64 serves. The bidirectional fan 40 , 64 at least one radial air flow direction 66 and an axial air flow direction 68 for cooling the axial flow machine 10 , especially for cooling the stator 20th or the stator winding 24 and the rotor 14th , on. The radial air flow direction 66 is essentially circular in the outer radius area of the bidirectional fan by a plurality 40 , 64 arranged radial air vanes 70 and the axial air flow direction 68 by a plurality in the inner radius area of the rotor yoke 62 arranged axial openings 72 achieved.

Thus, the bidirectional fan works 40 , 64 regarding 6th a radial suction 74 an air stream 76 with an axial flow 78 of the stator 20th and the rotor 14th the axial flow machine 10 and a radial exit 80 of the heated airflow 76 from one housing 82 the axial flow machine 10 . The radial suction 74 of the airflow 76 takes place on the one hand through the air gap between the stator teeth 44 (see. 2 ) and on the other hand in the area of the first stator yoke 26th of the stator 20th , especially on one of the rotor 14th seen from the distal end face 84 of the first stator yoke 26th .

In 7th is the axial flow machine 10 with their case 82 including a lid that closes this 86 shown. 8th shows the case 82 without axial flow machine 10 and lid 86 . The case 82 is open on one side to accommodate the cover 86 and has a substantially closed end face opposite 88 (see. 8th ) on. The lid 86 closes the housing 82 and thus connects the stator with a force fit 20th and the rotor 14th the axial flow machine 10 . In this context, “essentially closed” should be understood to mean that the end face 88 a plurality of openings 90 for example for cooling, as cable openings and / or as a feedthrough for the machine shaft 12th may have, but alternatively also that the end face 88 is completely closed. The case 82 is cylindrical and fixes the stator 20th such that a defined air gap between the rotor 14th or its magnetic ring 18th and the stator 20th or its winding carrier 22nd arises. To reduce or avoid eddy current losses, the housing is 82 made of a magnetically insulating material with the lowest possible permeability such as plastic (PA66). The cover can also do the same 86 be trained.

While in a bearing flange 92 of the lid 86 that as a fixed camp 30th trained first camp 28 is fixed that the machine shaft 12th immovably mounted, has the essentially closed end face 86 of the housing 82 in another bearing flange 94 that as a loose bearing 38 trained second camp 36 for movable mounting of the machine shaft 12th on. In this way the housing can 82 very easy after assembling the axial flow machine 10 can be postponed and removed again for any service work.

On its open side are around the circumference of the case 82 alternately distributes a plurality of recesses 96 and tabs 98 for holding and fixing the stator 20th arranged. The first and second stator yokes extend over the circumference 26th , 42 of the stator 20th distributed radial projections (cf. 2 and 3 ) in the respective recesses 96 of the housing 82 . The lid also contains the same 86 as tabs 106 formed radial projections that fit into the recesses 96 of the housing 82 intervention. In this way, the high axial forces of the axial flow machine 10 towards the lid 86 be discharged. In every flap 98 of the housing 82 is at least one hole 100 to fix the lid 86 and consequently also of the stator 20th by means of appropriate fasteners 102 , especially screws 104 , intended. The Fasteners 102 transfer the axial force of the axial flow machine 10 on the housing 82 and are thus subjected to shear stress.

The openings 90 on the essentially closed end face 88 of the housing 82 are as radially and / or axially acting ventilation openings 104 , especially as ventilation outlets 106 , for cooling the axial flow machine 10 trained (see also 6th ). In addition, the housing 82 approximately in the middle between the essentially closed end face 88 and that in the axial direction A. opposite open side a plurality of radially acting ventilation openings distributed over the circumference 108 , especially ventilation inlets 110 , on. Next to the openings 90 for cooling the axial flow machine 10 are particularly in the tabs 98 of the housing 82 more openings 90 provided as bushings 112 can serve for sensor lines or the like.

In 9a is a schematic of the stator winding 22nd as a triangle-parallel connection 48 of the six individual tooth windings 46 the stator teeth 44 (see. 2 ) shown. There are two individual tooth windings per phase 46 connected in parallel between the connection points U and V, V and W or W and U. The triangle connection as such causes that on each individual tooth winding 46 the entire supply voltage drops. This requires an increase in the number of turns of the individual tooth windings 46 in order to achieve a specifically required speed in motor operation or a specifically required energy yield in generator operation. The additional parallel connection allows the winding wire diameter to be increased in a particularly advantageous manner and thus the resulting internal resistance to be reduced. The triangle-parallel connection 48 thus enables the internal resistance of the axial flow machine to be reduced 10 compared to a conventional star connection, which leads to a significant increase in the performance of the axial flow machine 10 compared to previous solutions. 9b shows an alternative embodiment of the triangle-parallel connection 48 for a total of nine individual tooth windings 46 the stator winding 22nd .

In 10 Figure 3 is one embodiment of an electrical processing device 34 with the axial flow machine according to the invention 10 according to 1 shown. The electrical processing device 34 is called an electric machine tool 112 in the form of a mains powered hammer drill with an electric motor driven hammer mechanism 114 who have favourited a drill chuck 116 for an insert tool, not shown, set in a rotary and / or percussive movement. The exact design of the hammer drill is not to be discussed in more detail here, since this is well known to the person skilled in the art. Any other battery-powered or mains-operated electric machine tool can also be used as an electrical processing device 112 to be understood for the machining of workpieces by means of an electrically driven insert tool. The electrical processing device can be designed both as a handheld electrical tool and as a stationary electrical machine tool. Typical electric machine tools in this context are hand or standing drills, screwdrivers, impact drills, rotary hammers, demolition hammers, planes, angle grinders, orbital grinders, polishing machines or the like. Motor-driven gardening equipment such as lawn mowers, lawn trimmers, pruning saws or the like can also be used as electrical processing equipment. Furthermore, the invention can be applied to axial flow machines in household and kitchen appliances, such as washing machines, dryers, vacuum cleaners, mixers, etc.

The axial flux machine working as an axial flux motor 10 the power tool 112 drives by means of its machine shaft 12th the striking mechanism in a familiar way 114 via a transmission 118 at. The control of the axial flow machine 10 takes place via one in a D handle 120 the power tool 112 arranged main switch 122 with electronics (not shown) for energizing the triangular parallel circuit 48 interconnected stator winding 22nd cooperates. The stator 20th the axial flow machine 10 is right in the case 32 the power tool 112 recorded. To do this are the stator 20th and the case 32 Permanently connected to one another by a joining process, in particular glued. Alternatively, the stator 20th but also permanently with the housing by means of a form fit 32 connected, in particular pressed. It can also be provided that the housing 32 or a gearbox 122 the power tool 112 the one with the machine shaft 12th the axial flow machine 10 connected second camp 36 , especially as a floating bearing 38 , records. Instead of the axial flow machine shown 10 according to 1 can the power tool 112 or the electrical processing device 34 without restricting the invention also with an axial flow machine 10 according to the 6th to 8th be equipped.

Finally, it should be pointed out that the invention does not apply to the exemplary embodiments shown in accordance with FIG 1 to 10 is still limited to the specified number of stator teeth, individual tooth windings and magnets of the magnetic ring.

QUOTES INCLUDED IN THE DESCRIPTION

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Patent literature cited

• DE 102015223766 A1 [0004]

Claims (2)

Axial flux machine (10), in particular one-sided axial flux motor, for an electrical machining device (34), with a machine shaft (12), in particular a motor shaft, a disk-shaped stator (20) and a machine shaft (12) adjacent to the stator (A) in the axial direction (A) 20) arranged disc-shaped rotor (14), the stator (20) being designed as a winding carrier (22) for at least one stator winding (24) and the rotor (14) connected non-rotatably to the machine shaft (12) relative to the stator (20) in a rotary movement is displaceable, characterized in that the stator (20) has a plurality of stator teeth (44) each with a single tooth winding (46) of the stator winding (24), the stator winding (24) as a triangular parallel connection (48 ) the single-tooth windings (46) is formed. Electrical processing device (34), in particular an electric machine tool (112), with an axial flux machine (10) Claim 1 .

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