GB2640595A - Stator - Google Patents

Abstract

A stator 400 comprising: a laminated stator stack 410; an annular manifold 420 to carry coolant to the stator; and one or more fastening members (430, Fig. 4) to secure the manifold to the stator. There may be a gasket 450 (Figs. 6 and 9) of elastic material between the manifold and stator, perhaps to seal the windings and rotor from the coolant. The manifold may comprise a coolant cavity formed between the manifold and the stator which may allow coolant to enter between feet (422, Fig. 8) and pass into axial coolant passages 412 in the stator. The fastening members may comprise: solid rivets (530, Fig. 15); blind or pop rivets (430, Figs. 10-11); bolts (530, Fig. 15); plastic plugs such as plastic rivets or plastic friction fasteners; and/or interlocking, latching protrusions on the manifold and stator 640, 645. The stator and manifold may be used in a battery powered motor for an electric vehicle. The stator may be manufactured by assembling the stator stack, attaching the manifold, and then perhaps using heat-cured epoxy to attach further members such as windings.

Description

STATOR

TECHNICAL FIELD

The present disclosure relates to a stator. Aspects of the invention relate to a stator and to a motor assembly and vehicle comprising a stator. Aspects of the invention relate to a method of manufacturing a stator.

BACKGROUND

It is known to provide a stator as part of the electromagnetic system of a vehicle. The stator works in combination with a rotor, and together may be used as a generator or as a motor. When a stator and rotor are used as a generator, the mechanical rotation of the rotor with respect to the stator generates an electrical current in windings of the stator. When a stator and rotor are used as a motor, electrical current in the windings is used to drive rotation of the rotor with respect to the stator. During manufacture, installation and use the stator may be subject to a wide range of forces and temperatures, and it is therefore important that the stator is durable.

It is an aim of the present invention to address one or more of the disadvantages associated with the prior art.

SUMMARY OF THE INVENTION

Aspects and embodiments of the invention provide a stator, a motor assembly, a vehicle and a method of manufacturing a stator as claimed in the appended claims According to an aspect of the present invention there is provided a stator comprising a stator stack and a manifold, the manifold being fastened to the stator stack by at least one fastening member. Advantageously, the fastening member may secure the stator stack to the manifold in use.

According to an aspect of the present invention there is provided a stator comprising: a stator stack, the stator stack comprising a plurality of laminated layers; a manifold configured to allow coolant to the stator stack; and one or more fastening members. The manifold is arranged so that a first surface of the manifold is adjacent to a first surface of the stator stack. The manifold is fastened to the stator stack by the one or more fastening members.

Advantageously, using a fastening member provides a durable fastening between the manifold and the stator stack. In particular, a fastening member may be resistant to changes in temperature which might cause other fastening techniques, such as an adhesive, to weaken.

The stator stack may comprise a plurality of laminated layers, the stator stack further comprising at least a first coolant duct and a second coolant duct, the first coolant duct having an opening on the first surface of the stator stack and the second coolant duct having an opening on the first surface of the stator stack.

The manifold may comprise one or more coolant cavities on the first surface of the manifold. The manifold may be arranged so that the first surface of the manifold is adjacent to the first surface of the stator stack, such that the first coolant duct and the second coolant dud open into a first coolant cavity of the manifold. Advantageously, in use, coolant can then flow into the first coolant duct and the second coolant duct via the first coolant cavity of the manifold.

A duct may be a passageway through the stack. A duct may comprise a plurality of holes bored, stamped or cast through a plurality of the laminated layers of the stack so as to form a passage with an opening on the first surface. A coolant cavity of the manifold may comprise a duct or passageway through the manifold. The fastening member may urge one or more of the laminated layers of the stator stack towards the first surface of the manifold. The fastening member may urge a plurality of the laminated layers of the stator stack towards the first surface of the manifold. Advantageously, urging a plurality of laminated layers of the stator stack towards the first surface of the manifold may help to keep the laminated layers positioned correctly with respect to one another, as well as with respect to the manifold.

The coolant may be an oil.

The fastening member may fasten the manifold to the stator stack mechanically. The fastening member may be arranged to urge the manifold against the stator stack.

At least one of the one or more fastening members may comprise a rivet. The head of the rivet may be positioned against the stator stack, in use. The head of the rivet may be positioned against the manifold, in use. The rivet may pass through the manifold and through one or more laminated layers of the stator stack. The rivet may be made of metal. Advantageously, a rivet is a durable fastening member which can withstand the forces and temperature changes commonly found in stators during both their manufacture and use.

At least one of the one or more fastening members may comprise a blind rivet. The blind rivet may comprise a mandrel and a rivet body. During installation, the mandrel may be pulled into the rivet body, so that the head of the mandrel causes the rivet body to deform and clamp around the stator stack and manifold. The mandrel head and deformed section of the rivet body may abut against the stator stack, while a preformed lip of the rivet body abuts against the manifold. The mandrel head and deformed section of the rivet body may abut against the manifold, while a preformed lip of the rivet body abuts against the stator stack. Advantageously, a blind rivet can be installed without needing to apply a flattening force to the exterior of the tail of the rivet, so that the blind rivet can be installed in spaces or around components for which other rivet types may not be suitable.

At least one of the one or more fastening members member may comprise a bolt. The bolt may pass through the manifold and through one or more laminated layers of the stator stack. The head of the bolt may be positioned against the manifold or the stator stack in use. The head of the bolt may be positioned within a recess of the manifold or the stator stack, in use. The bold may be made of metal. A nut may be positioned against the other of the manifold or the stator stack from the head of the bolt, in order to receive a threaded end of the bolt, in use. A nut may be positioned within a recess of the other of the manifold or the stator stack from the head of the bolt, in order to receive a threaded end of the bolt, in use. The nut may be made of metal.

The manifold may comprise a threaded recess for receiving the threaded end of the bolt. The stator may comprise a threaded recess for receiving the threaded end of the bolt. Advantageously, a bolt is a durable fastening member which can withstand the forces and temperature changes commonly found in stators during both their manufacture and use.

At least one of the one or more fastening members may comprise a plastic plug. The plastic plug may fasten the manifold to the stator stack by plastically deforming, by screwing into a matching recess or nut, or by achieving a friction fit. Advantageously, plastic plugs may provide an easily manufactured and installed fastening member that is still able to withstand the forces and temperature changes commonly found in stators during both their manufacture and use.

A fastening member may comprise a clip or band which fastens or wraps around the outside of the stator stack and manifold. Advantageously such a fastening member may be easily installed.

It may be that the manifold comprises a first protrusion and the stator stack comprises a second protrusion, the first protrusion being arranged to engage with the second protrusion when the manifold is fitted to the stator stack so that the manifold is fixed to the stator stack. The first protrusion and the second protrusion may be fastening members. The manifold may be urged towards the stator stack by the first protrusion and the second protrusion. It may be that one or both protrusions needs to deform in order to fit the manifold to the stator stack.

The deformation of the protrusion may be elastic, and may relax as the first surface of the manifold comes into contact with the first surface of the stator stack, so that removal of the manifold from the stator stack requires a further deformation of at least one of the protrusions. The first protrusion and second protrusion may together form a clip, catch or latch. The second protrusion may comprise a plurality of laminated layers of the stator. The second protrusion may be separated from the first surface of the manifold by a plurality of laminated layers of the stator stack. The stator stack may comprise a plurality of first protrusions, each arranged to engage with a second protrusion on the manifold. The manifold may comprise a plurality of second protrusions, each arranged to engage with a first protrusion on the manifold. Advantageously, the first protrusion and a second protrusion can be used to fasten the manifold to the stator stack without requiring as many further components, such as rivets, bolts and plugs.

It may be that the stator further comprising an elastic member located between the first surface of the manifold and the first surface of the stator stack. The elastic member may be a ring. The elastic member may be elastically deformed when the stator stack is fastened to the manifold. The elastic member may urge the first surface of the manifold away from the stator stack first surface of the stator stack. The elastic member may form a surface of the coolant cavity. Advantageously, the elastic member may help to secure the stator stack in relation to the manifold by providing a force which works against the fastening. Advantageously, the elastic member may prevent coolant flowing out of the stator by passing between the stator stack and the manifold in undesired locations.

It may be that the manifold comprises a coolant cavity which extends to a surface of the manifold other than the first surface so that lubricant can flow into or out of the stator through the coolant cavity. Advantageously such an arrangement allows coolant to pass into and out of the stator so that the stator may be cooled.

According to another aspect of the invention, there is provided a motor assembly comprising a stator as described above. The motor assembly further comprises a battery, wherein the battery is electrically connected to the stator. Advantageously, a stator as describe above may provide part of the electromagnetic circuit in a motor assembly.

According to another aspect of the invention, there is provided a vehicle comprising a vehicle body and the motor assembly describe above, wherein the motor assembly is attached to the vehicle body. Advantageously, a motor assembly as described above may provide motive power to the vehicle.

According to another aspect of the invention, there is provided of manufacturing a stator, the stator being as described above and the method comprising: laminating layers of the stator stack; and fastening the stator stack to the manifold using the one or more fastening members. Advantageously, the stator is then fastened together for use.

The method may further comprise: fitting at least one first member comprising an epoxy on at least the stator stack or the manifold; and heating the at least one first member so that the epoxy cures and adheres the at least one first member in place. The first member may be a winding. The first member may be a hairpin. Advantageously, the fastening member may be chosen so as to remain fastened during the curing process.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a vehicle in accordance with an embodiment of the invention; Figure 2 shows a block diagram of the vehicle of Figure 1; Figure 3a shows a rotor stator assembly in accordance with an embodiment of the invention; Figure 3b is an exploded diagram of the rotor stator assembly of Figure 3a; Figures 4 and 5 show a stator in accordance with an embodiment the invention; Figure 6 is an exploded diagram of the stator of Figures 4 and 5; Figures 7 and 8 show a manifold in accordance with an embodiment of the invention; Figure 9 shows the manifold of Figures 7 and 8 in combination with an elastic member in accordance with an embodiment of the invention; Figure 10 shows a fastening member in accordance with an embodiment of the invention; Figure 11 shows a cut away section of the stator of Figures 4 and 5; Figures 12 and 13 show a blind rivet; Figure 14 is a side view of a stator according to an another embodiment of the invention; Figure 15 shows a cut away section of the stator of Figure 14; Figure 16 is a flow chart of a method of manufacturing a stator according to the invention.

DETAILED DESCRIPTION

A vehicle 100 in accordance with an embodiment of the present invention is described herein with reference to the accompanying Figure 1. Figure 2 shows a block diagram of components of the vehicle 100, the vehicle 100 comprising a battery 110 and a rotor stator assembly 200. Figure 3a shows the rotor stator assembly 200. The vehicle 100 may be a battery electric vehicle, a plug-in hybrid vehicle, or a mild hybrid vehicle, for example.

The battery 110 is for supplying electrical power to the rotor stator assembly 200, or receiving electrical power from the rotor stator assembly 200.

The rotor stator assembly 200 comprises a rotor 300 and a stator 400. Figure 3b is an exploded diagram of the rotor stator assembly 200 in which the rotor 300 is shown removed from the stator 400. In use, the rotor 300 sits within the stator 400 as shown in Figure 3a and the rotor 300 is able to rotate with respect to the stator 400 around axis 310. If electrical power is applied to the rotor stator assembly 200, then the rotor stator assembly 200 can drive a rotation of the rotor 300 with respect to the stator 400. Alternatively, if a rotational force is applied to the rotor 300 such that it rotates with respect to the stator 400, then the rotor stator assembly 200 can generate electrical power.

Figures 4 and 5 show the stator 400. The stator 400 comprises a stator stack 410 and a manifold 420, the manifold 420 being fastened to the stator stack 410 by fastening members, the fastening members comprising six blind rivets 430. The stator stack 410 comprises a plurality of layers which are laminated together using an adhesive, so as to form a stack. The stator stack 410 comprises a plurality of coolant ducts 412. Each coolant duct is a duct connecting a hole in a surface of the stator stack 410 adjacent to the manifold 420 with another hole in a surface of the stator stack 410 opposite to the surface adjacent to the manifold. As can be seen in Figure 5 the holes of the coolant ducts 412 in the surface of the stator stack 410 opposite to the surface adjacent to the manifold 420 may be arranged in a ring adjacent to an outer circumference of the stator stack 410. The statorstack 410 further comprises a plurality of wedges 414 arranged around its inner rim, the wedges 414 surrounding the central void 416 where the rotor 300 sits in the rotor stator assembly 200. In use the stator 400 is provided with hairpins (not shown) which are fitted in slots between the wedges 414 and which act as a winding for the stator 400.

Figure 6 shows an exploded diagram of the stator 400, in which can be seen the stator stack 410, the manifold 420 and an elastic member 450. As can be seen in Figure 5 the holes of the coolant ducts 412 in the surface of the stator stack 410 adjacent to the manifold 420 are likewise arranged in a ring adjacent to an outer circumference of the stator stack 410. The elastic member 450 is a ring which sits, in use, on the surface of the stator stack 410 adjacent to the manifold 420, between the stator stack 410 and the manifold 420. The elastic ring 450 is located, in use, between the ring of holes of the coolant ducts 412 and the wedges 414. When the manifold 420 is urged towards the stator stack 410 by the fastening members, therefore, the elastic ring 450 is compressed against the face of the stator and forms a seal which prevents a flow of coolant from the coolant ducts 412 to the wedges 414 and hairpins in between.

Figures 7 and 8 show the manifold 420. The outer ring of the manifold 420 comprises a plurality of feet 422 which abut against the stator stack 410 in use. An inner ring of the manifold comprises a circular indentation 424 which receives the elastic member 450, as shown in Figure 9.

When the stator 400 is assembled a cavity is formed between the manifold 420, the stator stack 410 and the elastic member 450. The cavity is open to the exterior of the stator 400 between the feet 422 of the manifold 420. The cavity is also open to the holes of the ducts 412 which are arranged on the surface of the stator stack 410 adjacent to the manifold 420. As such, coolant can be pumped into the stator 400 so that it passes into the stator 400 between and around the feet 422 of the manifold 420, into the cavity and from the cavity into the coolant ducts 412. The coolant may then leave the stator 400 through the holes of the coolant ducts 412 which are located on the surface of the stator stack 410 which is opposite to the surface of the stator stack 410 adjacent to the manifold 420.

The manifold 420 further comprises a sealing ring 426 which is located on an outer circumferential surface of the manifold, next to the feet 422. The sealing ring 426 is made from elastic material and establishes a seal between the manifold 420 and a housing that contains the rotor stator assembly 200 within the vehicle 100. The sealing ring 426 therefore prevents coolant from leaving the container by passing over a side of the manifold 420 which is located opposite to the stator stack 410.

Figure 10 shows one of the blind rivets 430 of the stator 400 (after expansion of its tail 433). The blind rivet 430 comprises a mandrel head 432, a rivet body 434 (which extends to the tail 433 with equal diameter prior to expansion) and a rivet setting head 436. Figure 11 shows a cross section through the stator 400 which shows the blind rivet 430 in situ after expansion. The blind rivet 430 fits into a pre-formed hole 438 in the stator stack 410, which is formed from laminations of the stack having different plans when assembled together whereby an internal ledge 439 is formed in the hole 438. That is, the laminations disposed near the manifold are provided with holes having different (and smaller) diameters than corresponding holes in laminations further from the manifold. At a depth corresponding to the length of the rivet body 434 (taking account of the thickness of the mandrel 420), laminations further from the manifold have no holes, whereby the holes 438 are blind holes. Corresponding through holes are also formed in the manifold 420 to receive the rivet body 434 and such that the rivet setting head 436 abuts against an outer surface of the manifold 420, and the tail 433 of the rivet body, when expanded, abuts against the ledge 439 of the stator stack 410. In so doing, the rivet urges the stator stack 410 against the manifold 420.

Figures 12 and 13 illustrate the installation of a blind rivet 430. Figure 12 shows the blind rivet 430 before installation, when it further comprises a mandrel body 438 which is joined to the mandrel head at a break point 440. During installation, the rivet is inserted into the pre-formed hole in the stator stack 410 and manifold 420 before the mandrel body 438 is drawn away from the manifold 420 while the rivet setting head 436 is driven towards the manifold 420. This has the effect of, first, drawing the mandrel head 432 into the rivet body 434 so that the tail 433 of rivet body 434 expands outwards and is fastened against the stator stack 410, and second, causing the mandrel body 438 to break away from the mandrel head 432 at the break point 440.

Figure 14 shows another stator 500. Figure 15 shows a cross section through the stator 500. The stator 500 can be used in a rotor stator assembly 200 and in a vehicle 100 in the same way as the stator 400, discussed above. The stator 500 comprises a stator stack 510, a manifold 520 and an elastic member 550. The stator 500 is similar to the stator 400 except for those differences stated below.

The fastening members of the stator 500 here comprise bolts 530 having heads 535. The bolts are inserted through holes 540 pre-formed into the stator stack 510 such that the head of the bolt abuts against an interior surface of the stator stack 510. The manifold 520 comprises a threaded hole into which the bolt is screwed, such that the manifold 520 is urged against the stator stack 510 and the elastic member 550. In this case, a through hole 540 is provided extending through the stator stack, so that the head 535 of the bolts can be accessed with a fastening tool from the opposite side of the stator stack. This stator lamination stack has the advantage of fewer lamination plans being required.

Instead of blind rivets, a rivet may be employed comprising a head and tail that is inserted in through holes like those of Figure 15 and pre-formed into the stator stack 510, such that the head of the rivet abuts against an interior ledge surface of the through-hole 540 and the (unexpanded) tail extends through the manifold 520.

Force is then exerted on the tail such that it expands outwards and is fastened against the manifold 520. A tool (not shown), inserted through the bore 540, retains the rivet in position. The manifold 520 is therefore urged against the stator stack 510. Alternatively or additionally, a rivet of the stator stack 500 may comprise a head and tail and be inserted through the manifold 520 into the hole 540 pre-formed into the stator stack 610 such that the head of the rivet abuts against an outer surface of the manifold 520. Force is then exerted on the tail, whilst a tool is pressed against the head of the rivet, such that the tail expands outwards and is fastened against the interior surface of the stator stack 510. The manifold 520 is therefore urged against the stator stack 510.

In a different embodiment, fastening members (not shown) for the manifold of the stator comprise a plastics material plug. The plastic plug fastens the stator stack to the manifold by being passed through preformed holes in the stator stack and the manifold and then being deformed so as to urge the manifold against the stator stack. Additionally or alternatively a plastic plug of the stator may be threaded and may screw into a matching recess or nut, similar to the bolt 530 described above. Additionally or alternatively a plastic plug of the stator may achieve a friction fit.

Fastening of manifold 420,520 to the stator 400,500 may additionally or alternatively comprise one or more clips 640 on the manifold 420,520 which fasten (snap into) the outside of the stator stack in a notch 645 on its outside surface, the notch having an undercut to receive a barb on the clip 640. The clip is deflected outwardly as the manifold is offered up to the stator and snaps into engagement with the notch after compression of the sealing member 450. A band (not shown) may also be employed to wrap around both the stator stack and manifold.

The fastening members of the stator and manifold may alternatively comprise the manifold having a first protrusion and the stator stack having a second protrusion, the first protrusion being arranged to engage with the second protrusion when the manifold is fitted to the stator stack, whereby the manifold is fixed to the stator stack. The first protrusion and the second protrusion elastically deform to accommodate one another as the manifold is offered up to the stator stack, and then engage so that the manifold is urged towards the stator stack by the force of the returning elastic deformation. The second protrusion comprises a plurality of layers of the stator stack 910.

Fastening members described above may be used in combination. For example, a stator 400,500 may comprise any combination of rivets, bolts, plastic plugs, clips, bands and first and second protrusions. Furthermore, a stator may include any number of fastening members.

In addition to the fastening members discussed above adhesives may be used. For example, a stator of a rotor stator assembly 200 may comprise adhesive between the stator stack 410,510 and the manifold 420,520 such that the adhesive bonds the stator stack to the manifold.

Figure 16 is a flow chart of a method of manufacturing a stator. The method maybe used in manufacturing the stators 400,500 described above. The method comprises laminating layers together to form a stator stack 410, 510 in step 2010 and fastening the stator stack to a manifold using one or more fastening members in step 2020. The method may then further comprise fitting one or more first members such as windings or hairpins on the stator 400,500 in step 2030, the first members comprising an epoxy, and in step 2040 heating the first members so that the epoxy cures.

It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application.

Claims (13)

1. CLAIMS1. A stator comprising: a stator stack, the stator stack comprising a plurality of laminated layers; a manifold configured to allow coolant to the stator stack; and one or more fastening members, the manifold being arranged so that a first surface of the manifold is adjacent to a first surface of the stator stack, the manifold being fastened to the stator stack by the one or more fastening members.
2. 2. A stator according to claim 1, wherein at least one of the one or more fastening members comprises a rivet.
3. 3. A stator according to claim 2, wherein at least one of the one or more fastening members comprises a blind rivet.
4. 4. A stator according to any preceding claim, wherein at least one of the one or more fastening members comprises a bolt.
5. 5. A stator according to claim 4, wherein the manifold comprises a threaded recess for receiving the threaded end of the bolt.
6. 6. A stator according to any preceding claim, wherein at least one of the one or more fastening members comprises a plastic plug.
7. 7. A stator according to any preceding claim, wherein the manifold comprises a first protrusion and the stator stack comprises a second protrusion, the first protrusion being arranged to engage with the second protrusion when the manifold is fitted to the stator stack so that the manifold is fixed to the stator stack.
8. 8. A stator according to any preceding claim, the stator further comprising an elastic member located between the first surface of the manifold and the first surface of the stator stack.
9. 9. A stator according to any preceding claim, wherein the manifold comprises a coolant cavity which extends to a surface of the manifold other than the first surface so that lubricant can flow into or out of the stator through the coolant cavity.
10. 10. A motor assembly comprising the stator of any preceding claim, the motor assembly further comprising a battery, wherein the battery is electrically connected to the stator.
11. 11. A vehicle comprising a vehicle body and the motor assembly of claim 10, wherein the motor assembly is attached to the vehicle body.
12. 12. A method of manufacturing a stator according to any of claims 1 to 9, the method comprising: laminating layers of the stator stack; and fastening the stator stack to the manifold using the one or more fastening members.
13. 13. A method according to claim 12, the method further comprising: fitting at least one first member comprising an epoxy on at least the stator stack or the manifold; and heating the at least one first member so that the epoxy cures and adheres the at least one first member in place.