Stator and method for cooling the winding heads of a stator

Abstract

A stator for an electrical machine is described. The stator comprises a stator body with a plurality of stator slots, each extending from the first end face to the opposite second end face of the stator body, and stator windings arranged in the plurality of stator slots, which form a first winding overhang on the first end face of the stator body and a second winding overhang on the second end face of the stator body. The stator further comprises a first coolant inlet, which is designed to conduct coolant to the first winding overhang and from the first end face of the stator body into the plurality of stator slots, and a second coolant inlet, which is designed to conduct additional coolant to the second winding overhang in addition to the coolant exiting from the plurality of stator slots at the second end face of the stator body.

Description

[0001] The invention relates to an electrical machine, such as a synchronous machine. In particular, the invention relates to the reliable cooling of the winding heads of the stator of an electrical machine.

[0002] An at least partially electrically powered vehicle includes an electric machine for driving the vehicle. The electric machine includes a stator that encloses a rotor of the electric machine. Furthermore, the electric machine typically has a coolant circuit for cooling the electric machine, in particular the electrical windings of the stator.

[0003] This document deals with the technical task of achieving particularly efficient and reliable cooling of the stator windings, in particular the winding heads, of a stator of an electrical machine.

[0004] The problem is solved in each case by the individual independent claims. Advantageous embodiments are described, among other things, in the dependent claims. It should be noted that additional features of a patent claim dependent on an independent patent claim can form a separate invention, independent of the combination of all features of the independent patent claim, without the features of the independent patent claim or only in combination with a subset of the features of the independent patent claim, which invention can be made the subject of an independent claim, a divisional application or a subsequent application. This applies equally to technical teachings described in the description, which can form an invention independent of the features of the independent patent claims.

[0005] According to one aspect, a stator for an electrical machine, in particular for a synchronous machine, is described. The stator comprises a stator body with a plurality of stator slots, each extending from the first end face of the stator body to the opposite second end face of the stator body. The stator body can have, for example, 3 or more, 6 or more, or 9 or more, or 12 or more stator slots.

[0006] Furthermore, the stator comprises stator windings arranged in the plurality of stator slots, which form a first winding head on the first end face of the stator body and a second winding head on the second end face of the stator body. The stator windings can generate a three-phase current, which drives the rotor of the electric machine.

[0007] The stator further comprises a first coolant inlet configured to conduct coolant (from outside the stator) to the first winding head and (subsequently) from the first end face of the stator body into the plurality of stator slots. The coolant may comprise, in particular, oil.

[0008] The stator may have a first chamber surrounding the first winding head. The first chamber may be configured to shield coolant from the rotor of the electric machine. Furthermore, the first chamber may be configured to conduct coolant from the first chamber from the first end face of the stator body into the plurality of stator slots. The first inlet may be configured to conduct coolant (from outside the stator) into the first chamber. The coolant may be pumped, for example, by a pump through the first inlet into the first chamber.

[0009] Thus, coolant can be provided directly at the first end face to cool the first winding head and the stator windings arranged in the stator slots.

[0010] The stator further comprises a second coolant inlet configured to conduct additional coolant (directly from outside the stator) to the second winding head, in addition to the coolant exiting the plurality of stator slots on the second end face of the stator body. The additional coolant may comprise, in particular, oil. In particular, the additional coolant may be of the same coolant type as the coolant conducted through the plurality of stator slots.

[0011] The stator may have a second chamber surrounding the second winding head. The second chamber may be configured to shield coolant from the rotor of the electric machine. Furthermore, the second chamber may be configured to receive coolant exiting the plurality of stator slots at the second end face into the second chamber. The second inlet may be configured to conduct additional coolant (directly from outside the stator) into the second chamber.

[0012] In addition to the coolant provided by the stator slots, additional coolant is thus provided from outside the stator directly to the second end face. This allows for reliable cooling of the second winding head. Overall, the two coolant inlets ensure reliable and efficient cooling of the stator, particularly both winding heads.

[0013] The stator may have an outlet configured to conduct coolant from the second chamber. 100% of the coolant supplied via the first inlet and the second inlet may be conducted from the second chamber via the outlet. The coolant may then be directed to a cooling unit to cool the coolant. The cooled coolant may then be fed back to the stator via the first inlet or the second inlet. The coolant may be driven by a pump. This allows for particularly reliable cooling of the stator.

[0014] The stator can comprise a supply unit configured to divide a total volume flow of (cooled) coolant between the first inlet and the second inlet. The total volume flow can be effected by a coolant pump. The supply unit can be configured to direct more than 50%, in particular between 60% and 80%, approximately 70%, of the total volume flow of coolant to the first inlet (and thus to the first winding overhang and / or to the first end face of the stator body). Furthermore, the supply unit can be configured to direct the respectively complementary remainder of the total volume flow of coolant to the second inlet (and thus directly to the second winding overhang and / or to the second end face of the stator body). By dividing the total volume flow of (cooled) coolant in this way, particularly reliable cooling of the two winding overhangs of the stator can be achieved.

[0015] The stator can comprise a distribution element, in particular a distribution ring, which is designed to distribute the additional coolant provided via the second inlet along the circumference of the second winding head. For example, the distribution element, in particular the distribution ring, can have a plurality of openings, in particular nozzles, along the circumference of the second winding head, through which coolant can be guided from the second inlet to different locations on the second winding head. The openings can be evenly distributed along the circumference of the second winding head. This can further increase the cooling quality of the second winding head.

[0016] The stator may have one or more coolant channels in each of the individual stator slots of the plurality of stator slots, each of which is configured to conduct coolant from the first end face of the stator body to the second end face of the stator body.

[0017] The stator can have a slot insulation in each of the individual stator slots of the plurality of stator slots, which is designed to electrically insulate the one or more stator windings arranged in the respective stator slot from the stator body. The one or more coolant channels of the individual stator slots of the plurality of stator slots can each be at least partially delimited by the slot insulation of the respective stator slot.

[0018] By providing axial coolant channels in the individual stator slots, particularly reliable cooling of the stator windings in the stator slots can be achieved.

[0019] According to a further aspect, an electric machine having a rotor and a stator is described, wherein the stator is configured as described in this document. Furthermore, the electric machine may comprise a supply unit configured to conduct (cooled) coolant to the first inlet and to the second inlet of the stator.

[0020] The (cooled) coolant can be directed through the two inlets to the respective winding head. Furthermore, the coolant directed to the first winding head can be directed through the plurality of stator slots to the second winding head and / or to the second end face of the stator body. At the second end face, the coolant can be diverted to supply the coolant to a cooling unit before the cooled coolant is fed back to the two inlets via the supply unit.

[0021] A coolant circuit can thus be provided for efficient and reliable cooling of the stator windings in the stator slots and the winding heads of the stator.

[0022] According to a further aspect, a (road) motor vehicle (in particular a passenger car or a truck or a bus or a motorcycle) is described which comprises the electrical machine described in this document.

[0023] According to a further aspect, a method for cooling a stator of an electrical machine is described. The stator comprises a stator body with a plurality of stator slots, each extending from the first end face of the stator body to the opposite second end face of the stator body. Furthermore, the stator comprises stator windings arranged in the plurality of stator slots, which form a first winding overhang on the first end face of the stator body and a second winding overhang on the second end face of the stator body.

[0024] The method comprises conducting coolant to the first winding overhang and (further) from the first end face of the stator body into the plurality of stator slots. Furthermore, the method comprises conducting additional coolant, in addition to the coolant exiting from the plurality of stator slots at the second end face of the stator body, to the second winding overhang. Preferably, 60% to 80%, in particular 70%, of the total volume flow of the coolant is conducted through the plurality of stator slots to the second end face, and the complementary remainder of the total volume flow of the coolant is provided directly at the second end face.

[0025] It should be noted that the methods, devices, and systems described in this document can be used both alone and in combination with other methods, devices, and systems described in this document. Furthermore, any aspects of the methods, devices, and systems described in this document can be combined in a variety of ways. In particular, the features of the claims can be combined in a variety of ways. Furthermore, features listed in parentheses are to be understood as optional features.

[0026] The invention will be described in more detail below with reference to exemplary embodiments. Fig. 1a an exemplary electrical machine; Fig. 1b shows an exemplary winding head on an end face of a stator; Fig. 2a an exemplary cross-section through a stator; Fig. 2b a cross-section through an exemplary stator slot; Fig. 3 an isometric view of an end face of a stator body; Fig. 4a a cross-section of an exemplary stator slot; Fig. 4b a cross-section of an exemplary slot insulation; Fig. 5 an exemplary cooling of the stator of an electrical machine; and Fig. 6 a flowchart of an exemplary method for cooling the winding heads of the stator of an electrical machine.

[0027] As stated at the beginning, this document deals with increasing the efficiency and reliability of cooling of the stator windings and, in particular, the winding heads of a stator of an electrical machine. In this context, Fig. 1a shows an exemplary electric machine 100 in a view perpendicular to the shaft 101 of the electric machine 100. The shaft 101 of the electric machine 100 can correspond to the longitudinal axis of the stator 110 and / or the rotational axis of the rotor 120 of the electric machine 100. The shaft 101 runs along the z-axis of the illustrated Cartesian coordinate system.

[0028] The electric machine 100 comprises a stator 110 with a plurality of stator windings 111 arranged at different angular positions around the rotational axis of the rotor 120 and configured to generate an electromagnetic rotating field. The stator 110 is surrounded by a housing 135 of the electric machine 100. The individual stator windings 111 can each be arranged in a stator slot between two directly adjacent stator teeth 113 of the stator 110. An air gap 102 is arranged between the stator 110 and the rotor 120.

[0029] Furthermore, the electric machine 100 includes the rotor 120, which is driven by the rotating field generated by the stator 110. The rotor 120 is fixedly connected to the shaft 101 driven by the electric machine 100 (which shaft may be connected to the rotor axis of the rotor 120 or may correspond to the rotor axis of the rotor 120). The rotor 120 includes a rotor body 122.

[0030] The rotor 120 of an electrical machine 100 can have a laminated iron core (e.g., composed of mutually insulated laminations) as the rotor body 122. Similarly, the stator body of the stator 110 can also be composed of individual (mutually insulated) stator laminations (e.g., iron laminations).

[0031] A stator 110 extends along the rotational axis or the longitudinal axis of the rotor 120 from a first end face to an opposite second end face. The stator 110 has different magnetic stator teeth 113, which are arranged at different angular positions (evenly distributed) around the rotational axis of the rotor 120. A coil (i.e., one or more turns or windings 111) can be arranged around each of the stator teeth 113, by which a magnetic field is generated. The individual stator teeth 113 can thus form magnetic poles of the stator 110. The turns or windings 111 each form a winding head on the end faces of the stator 110.

[0032] A stator slot is formed between each two directly adjacent stator teeth 113 of the stator 110, in which the windings 111 are arranged. A stator slot extends along the longitudinal axis (i.e., along the z-axis) from the first end face to the opposite second end face of the stator 110. The windings 111 arranged in a stator slot can be electrically insulated from the (electrically conductive) stator body by means of slot insulation.

[0033] Fig. 1b illustrates the winding overhang 115 formed by the stator windings 111 on an end face 116 of the stator 110. The winding overhang 115 is typically cooled with a (liquid) coolant 130. The coolant 130 can, for example, be sprayed onto the winding overhang 115 using one or more nozzles (not shown). In the stator 110 described in this document, the coolant 130 for cooling the winding overhang 115 can be drawn at least partially from the stator slots of the stator 110.

[0034] Fig. Figure 2a shows a section of the air gap 102 and the adjacent rotor 120 and stator 110. In particular, Fig. 2a shows three stator slots 202, each arranged between two directly adjacent stator teeth 113. Stator windings 111 are arranged in the stator slots 202, each surrounded by a (prism-shaped) slot insulation 201. As already explained, the individual stator slots 202, the individual stator windings 111, and the individual slot insulation 201 each extend from a first end face 116 to the opposite second end face 116 of the stator 110 along the longitudinal axis, i.e., along the z-axis.

[0035] The individual stator teeth 113 can each have a stator shoe 203 at the end facing the air gap 102, which extends tangentially along the air gap 102. The stator shoes 203 of two directly adjacent stator teeth 113 form a wall of the intermediate stator slot 202 (with the wall running between the stator slot 202 and the air gap 102). However, the stator shoes 203 of the two directly adjacent stator teeth 113 typically do not touch each other, so that the stator slot 202 has a gap 204 toward the air gap 102, which gap extends along the longitudinal axis from the first end face 116 to the opposite second end face 116 of the stator 110. Fig. 2a shows a stator slot 202 marked with “B”, wherein the stator slot 202 in Fig. 2b is shown in enlarged form.

[0036] Fig. 3 shows a perspective view of a stator 110 (in particular a stator body). The stator slots 202 can be seen, each extending from the first end face 116 to the opposite second end face 116 of the stator body. Coolant 130 can be conducted through the individual stator slots 202, so that the coolant 130 is arranged in the immediate vicinity of the individual stator windings 111 and thereby effects particularly efficient and reliable cooling of the individual stator windings 111. The coolant 130 can, for example, be introduced into the individual stator slots 202 through a specially designed stator lamination (not shown) on the first end face of the stator body, and / or be discharged from the individual stator slots 202 through a specially designed stator lamination (not shown) on the second end face of the stator body.

[0037] Fig. 4a and Fig. 4b show an exemplary slot insulation 201 for a stator slot 202. The Fig. 4a and Fig. 4b shows a cross-sectional view of a stator lamination 400 of the stator body. The slot insulation 201 can be, for example, an injection-molded part made of an electrically insulating material (e.g., plastic).

[0038] The slot insulation 201 can be configured to (circumferentially) adhere to the inner walls 402 of a stator slot 202. Stator windings 111 can be arranged in the space enclosed by the slot insulation 201. The slot insulation 201 can thus electrically insulate the stator windings 111 from the inner walls 402 of a stator slot 202.

[0039] Furthermore, the slot insulation 201 can be configured to form one or more axially extending coolant channels 401. A coolant channel 401 can be configured as a cavity between a side wall 403 of the slot insulation 201 and a directly adjacent stator winding 111. The Fig. The slot insulation 201 shown in Figure 4b has eight individual coolant channels 401, wherein the individual coolant channels 401 extend in the axial direction from the first end face 116 to the opposite second end face 116 of the stator body of the stator 110.

[0040] The walls of the individual axial coolant channels 401 are preferably each formed by a side wall 403 of the slot insulation 201 and by the surface of at least one stator winding 111. As a result, coolant 130 flowing through the individual coolant channels 401 is in direct contact with one or more stator windings 111, which enables particularly efficient and reliable cooling of the individual stator windings 111 within a stator slot 202.

[0041] Fig. 5 shows an exemplary cross section through an electric machine 110 with a rotor 120 and a stator 110. The electric machine 110 has a winding head 115 on each of the two end faces 116 of the stator body. The stator 110 has axial coolant channels 401, wherein the individual coolant channels 401 each extend within a stator slot 202 from the first end face 116 to the second end face 116 of the stator body. Fig. In the example shown in Figure 5, the first end face 116 is arranged on the left and the second end face 116 is arranged on the right.

[0042] Coolant 130 is conducted via a first inlet 501 to the first winding overhang 115 arranged on the first end face 116. The first winding overhang 115 can be arranged in a first chamber 511 that surrounds the first winding overhang 115. The coolant 130 can be conducted into the first chamber 511 through the first inlet 501. The first chamber 511 is typically designed to be fluid-tight in such a way that no coolant 130 from the first chamber 511 reaches the rotor 120 and / or the air gap 102 between the rotor 120 and the stator 110. The first chamber 511 can be formed by an annular shell in which the first winding overhang 115 is arranged and which is covered by the first end face 116 of the stator body.

[0043] The coolant 130 is at least partially, and preferably completely, directed from the first chamber 511 into the axial coolant channels 401, and thus from the first end face 116 to the second end face 116 of the stator body. The coolant 130 can thus be used not only to cool the first winding overhang 115 but also to cool the stator windings 111 in the stator slots 202.

[0044] The second winding head 115 is arranged on the second end face 116, wherein the second winding head 115 is preferably arranged in a second chamber 512, which prevents coolant 130 from reaching the rotor 120 and in particular into the air gap 102 between the rotor 120 and the stator 110. The second chamber 512 can be formed by an annular shell in which the second winding head 115 is arranged and which is covered by the second end face 116 of the stator body.

[0045] The coolant 130 exiting the individual axial coolant channels 401 at the second end face 116 can thus be directed into the second chamber 512 and can be used to cool the second winding head 115. The coolant 130 from the axial coolant channels 401 typically has a relatively low physical pressure at the second end face 116, so that a sufficiently strong coolant jet cannot usually be formed at the second end face to be directed onto the second winding head 115 for cooling.

[0046] The Fig. The electrical machine 100 shown in Figure 5 has a second inlet 502 on the second end face 116, through which additional coolant 130 can be introduced into the second chamber 512. The additional coolant 130 can be introduced in such a way that, using the coolant 130 from the axial coolant channels 401 and the additional coolant 130, one or more sufficiently strong coolant jets and / or a sufficiently strong coolant flow can be generated to cool the second winding head 115.

[0047] Thus, additional coolant 130 can be provided at the second end face 116 to ensure reliable cooling of the second winding head 115.

[0048] The coolant 130 from the second chamber 512 can be conducted out of the second chamber 512 via an outlet 503. Furthermore, the coolant 130 can subsequently be cooled and can then be used again via the first inlet 501 and / or the second inlet 502 to cool the stator 110.

[0049] A cooling device for cooling a stator 110 is thus described, in which direct slot cooling takes place using a coolant 130 (e.g. oil). A coolant-tight encapsulation of the winding overhangs 115 and the coolant chamber of the stator 110 is used. In this case, efficiency losses caused by coolant 130 penetrating into the air gap 102 between the stator 110 and the rotor 120 can be reduced or eliminated. Particularly advantageous, in particular with regard to the hydraulics, is a cooling device in which the inflow of coolant 130 is effected on the first winding overhang side, and the coolant 130 is subsequently guided into the parallel slot channels 401 near the conductor, and the outflow of the coolant 130 takes place on the other, second winding overhang side.

[0050] As already explained above, the axial passage through the entire stator body can lead to a relatively weak coolant flow on the downstream side (i.e., on the second winding head side), since the coolant 130 exits the channels 401 with comparatively low kinetic energy, which can result in a relatively poor flow formation around the second winding head 115 on the downstream side. This hydraulically unfavorable situation can lead to reduced heat dissipation at the second winding head 115, since the formation of the local heat transfer coefficients is impaired.

[0051] As in connection with Fig. 5, an additional introduction of a flow, in particular a pulse flow, of coolant 130 can be effected on the outflowing, second, winding head side in order to improve the flow situation and thus the thermal situation on the second winding head side. The additionally introduced flow of coolant 130 can be directed in a targeted manner, with regard to the flow behavior and / or the turbulence characteristics around the second winding head 115, via a distribution element (e.g., via one or more annular channels) immediately after the inflow to different points on the second winding head 115 in order to effect particularly reliable cooling of the second winding head 115.

[0052] Fig.6 shows a flowchart of an exemplary method 600 for cooling the stator 110 of an electric machine 100. The stator 110 comprises a stator body with a plurality of stator slots 202, each of which extends (along the longitudinal axis of the stator 110) from the first end face 116 of the stator body to the opposite second end face 116 of the stator body. Furthermore, the stator 110 comprises stator windings 111 arranged in the plurality of stator slots 202, which form a first winding head 115 on the first end face 116 of the stator body and a second winding head 115 on the second end face 116 of the stator body.

[0053] The method 600 includes conducting 601 coolant 130 to the first winding head 115 and from the first end face 116 of the stator body into the plurality of stator slots 202. The coolant 130 can be conducted via a first inlet 501 (from outside the stator 110) into a first chamber 511 that surrounds the first winding head 115. The first chamber 511 can be formed by an annular shell into which the first winding head 115 is inserted. The shell can be covered by the first end face 116 of the stator body. Thus, a coolant-tight first chamber 511 can be provided for cooling the first winding head 115. The second chamber 512 at the second end face 116 can be configured accordingly.

[0054] The coolant 130 can be guided (e.g., forced) from the first chamber 511 from the first end face 116 into the plurality of stator slots 202, in particular into coolant channels 401, each of which is arranged within a stator slot 202. The coolant 130 from the first chamber 511 can thus be guided to the second end face 116 and to the second winding head 115.

[0055] The method 600 further includes directing 602 additional coolant 130, in addition to the coolant 130 exiting from the plurality of stator slots 202 at the second end face 116 of the stator body, to the second winding head 115.

[0056] In addition to the coolant 130 that has been conducted through the plurality of stator slots 202, additional (cooled) coolant 130 (from outside the stator 110) can thus be provided to the second end face of the stator body. This allows for efficient and reliable cooling of both winding overhangs 115 and of the stator windings 111 in the stator slots 202 of the stator 110.

[0057] The present invention is not limited to the embodiments shown. In particular, it should be noted that the description and figures are intended only to illustrate the principle of the proposed methods, devices, and systems by way of example.

Claims

[1] Stator (110) for an electrical machine (100); wherein the stator (110) comprises - a stator body having a plurality of stator slots (202) each extending from a first end face (116) of the stator body to an opposite second end face (116) of the stator body; - stator windings (111) arranged in the plurality of stator slots (202), which form a first winding head (115) on the first end face (116) of the stator body and a second winding head (115) on the second end face (116) of the stator body; - a first inlet (501) for coolant (130), which is designed to guide coolant (130) to the first winding head (115) and from the first end face (116) of the stator body into the plurality of stator slots (202); and - a second inlet (502) for coolant (130), which is designed to conduct additional coolant (130) to the second winding head (115) in addition to the coolant (130) emerging from the plurality of stator slots (202) on the second end face (116) of the stator body. [2] Stator (110) according to claim 1, wherein - the stator (110) has a first chamber (511) which surrounds the first winding head (115) and which is designed - to shield coolant (130) from a rotor (120) of the electric machine (100); and - to direct coolant (130) from the first chamber (511) from the first end face (116) of the stator body into the plurality of stator slots (202); and - the first inlet (501) is designed to guide coolant (130) into the first chamber (511). [3] Stator (110) according to one of the preceding claims, wherein - the stator (110) has a second chamber (512) which surrounds the second winding head (115) and which is designed - to shield coolant (130) from a rotor (120) of the electric machine (100); and - receiving coolant (130) exiting the plurality of stator slots (202) at the second end face (116) into the second chamber (512); and - the second inlet (502) is designed to guide coolant (130) into the second chamber (512). [4] Stator (110) according to claim 3, wherein the stator (110) has an outflow (503) which is designed to conduct coolant (130) from the second chamber (512), in particular to a cooling unit for cooling the coolant (130). [5] Stator (110) according to one of the preceding claims, wherein the stator (110) comprises a distribution element, in particular a distribution ring, which is designed to distribute the additional coolant (130) provided via the second inlet (502) along a circumference of the second winding head (115). [6] Stator (110) according to one of the preceding claims, wherein - the stator (110) comprises a supply unit which is designed to divide a total volume flow of coolant (130) between the first inlet (501) and the second inlet (502); and - the feed unit is set up, - to direct more than 50%, in particular between 60% and 80%, of the total volume flow of coolant (130) to the first inlet (501); and - to direct the respective complementary remainder of the total volume flow of coolant (130) to the second inlet (502). [7] Stator (110) according to one of the preceding claims, wherein the stator (110) has in each of the individual stator slots (202) of the plurality of stator slots (202) one or more coolant channels (401), each of which is designed to conduct coolant (130) from the first end face (116) of the stator body to the second end face (116) of the stator body. [8] Stator (110) according to claim 7, wherein - the stator (110) in each of the individual stator slots (202) of the plurality of stator slots (202) has a slot insulation (201) which is designed to electrically insulate the one or more stator windings (111) arranged in the respective stator slot (202) from the stator body; and - the one or more coolant channels (401) of the individual stator slots (202) of the plurality of stator slots (202) are each at least partially delimited by the slot insulation (201) of the respective stator slot (202). [9] Electrical machine (100) comprising - a rotor (120); - a stator (110) constructed according to any one of the preceding claims; and - a supply unit configured to supply coolant (130) to the first inlet (501) and to the second inlet (502) of the stator (110). [10] Method (600) for cooling a stator (110) of an electrical machine (100); wherein the stator (110) comprises - a stator body having a plurality of stator slots (202) each extending from a first end face (116) of the stator body to an opposite second end face (116) of the stator body; - stator windings (111) arranged in the plurality of stator slots (202), which form a first winding head (115) on the first end face (116) of the stator body and a second winding head (115) on the second end face (116) of the stator body; wherein the method (600) comprises, - guiding (601) coolant (130) to the first winding head (115) and from the first end face (116) of the stator body into the plurality of stator slots (202); and - guiding (602) additional coolant (130), in addition to the coolant (130) emerging from the plurality of stator slots (202) on the second end face (116) of the stator body, to the second winding head (115).

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