Electromagnetic device

Abstract

An electromagnetic device used in an oil, the electromagnetic device comprising: an outer casing (2); a movable shaft (4) supported by the outer casing (2); a coil core (53A, 53B, 58A, 58B) arranged within the outer casing (2) such that the movable shaft (4) is arranged on a common axis with the movable shaft; and a coil (70, 70A) embedded in an outer mold (54), the coil (70, 70A) being constructed by winding a conductor wire (50, 50A, 50B), in which a copper wire (51) is coated with an electrical insulating layer (52), onto the coil core (53A, 53B, 58A, 58B), wherein the electrical insulating layer (52) is removed from an end portion of the conducting wire (50, 50A, 50B), and the end portion of the conducting wire (50, 50A, 50B) is wound onto a fixing portion (8a) of a coil terminal (8, 8A, 8B, 8C) attached to the coil core (53A, 53B, 58A, 58B) to form a winding portion (90, 91), a solder retaining member (62, 63) is mounted such that it covers the winding portion (90, 91) of the lead wire (50, 50A, 50B) on the fixing portion (8a) and leaves portions of the coil terminals (8, 8A, 8B, 8C) uncovered, and the winding portion (90, 91) of the lead wire (50, 50A, 50B) is soldered to the fixing portion (8a) together with the solder retaining member (62, 63), wherein the solder (56) is filled into the solder retaining part (62, 63).

Description

[0001] This application is based on application number 2000-327225 filed in Japan on October 26, 2000, the contents of which are incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention

[0002] The present invention relates to an electromagnetic device such as a stepping motor, a solenoid valve or the like, which is used in, for example, an automobile continuously variable transmission. 2. Description of the state of the art

[0003] Fig. 6 is an external view of a permanent magnet stepper motor, Fig. 7 is a cross-sectional view along the line VII-VII in Fig. 6, Fig. 8 is a cross-sectional view taken along the line VIII-VIII in Fig. 7, Fig. 9 is a cross-sectional view along the line IX-IX in Fig. 7 and Fig. 10 is a partially exploded perspective view of the stepper motor in Fig. 7.

[0004] In the figures, a permanent magnet (PM) stepping motor 1 used in oil immersed form includes: a resin-made outer casing 2; a resin-made tubular casing 12 connected to the outer casing 2; a motor main body disposed within the outer casing 2; a shaft 4 acting as a movable shaft and rotated by the motor main body 3; and a converting mechanism 31 for converting the rotation of the shaft into rectilinear motion. Moreover, the outer casing 2 and the casing 12 form a cover.

[0005] The motor main body 3 includes a stator 5 attached to the outer casing 2, and a rotor 6 attached to the shaft 4. The stator 5 includes: coils 7, each of which is formed by winding a conductive wire having an electrical insulating layer on a copper wire surface; coil terminals 8 led out from the coils 7; connecting terminals 9 connected to the coil terminals 8; and an external connector 25 connected to the connecting terminals 9. The rotor 6 includes a sleeve 10 attached to the shaft 4, and a cylindrical permanent magnet 11 magnetized in the circumferential direction, fitted over and attached to the sleeve 10.

[0006] The housing 12 is attached to the outer casing 2 by a plurality of screws 12a extending parallel to the shaft 4. A circular intermediate fitting opening 2a is formed in the outer casing 2, and an intermediate fitting portion 12a for insertion into the intermediate fitting opening 2a is formed on the housing 12. As shown in Fig. As shown in Fig. 8, three positioning protrusions 12b, which protrude in the radial direction and come into contact with an inner peripheral surface of the intermediate fitting opening 2a, are formed on an outer peripheral surface of the intermediate fitting portion 12a. Furthermore, an annular groove 12c is formed on a connecting surface of the housing 12 where the housing 12 converges with the outer housing 2.

[0007] A housing connection opening 12d connecting the inner and outer portions of the housing 12 is disposed on a side surface portion of the housing 12. A filter 13 for trapping impurities contained in the oil is disposed in the housing connection opening 12d. The shaft 4 is rotatably supported by a housing bearing 14 and a housing bearing 15. The housing bearing 15, which is mounted inside the housing 12, is a rubber seal.

[0008] A rod 16, which reciprocates in the axial direction of the shaft 4 by rotation of the shaft 4, is arranged on an upper portion of the housing 12. A base end portion of the rod 16 is inserted inside the housing 12, and an upper portion of the rod 16 protrudes from the upper portion of the housing 12. A rod connection hole 16a, which connects the inner portion of the housing 12 and an inner portion of the rod 16, is formed in the rod 16. A sleeve 17 for guiding the rectilinear movement of the rod 16, an oil seal 18 for preventing contaminants from entering from an outer peripheral portion of the rod 16, and an annular stopper 19 for regulating the forward movement of the rod 16 are attached to an inner peripheral surface of the upper portion of the housing 12.

[0009] The conversion mechanism 31 includes a threaded portion 4a, a resin-made guide member 20 formed in the base end portion of the rod 16 and engaged with the threaded portion 4a, and a stopper 21 made of metal, attached to the shaft 4, and regulating the reverse movement of the rod 16. Stop surfaces 20b and 21a, which are perpendicular to the rotational direction of the shaft 4, are formed on the guide member 20 and the stopper 21, respectively. As shown in Fig. As shown in Fig. 9, a rotation regulating projection portion 20a, which protrudes in the radial direction and regulates the rotation of the rod 16, is formed on an outer peripheral portion of the guide member 20. Consequently, the guide member 20 is displaced in the axial direction of the shaft by rotation of the shaft 4. A resin-made operating member 22 is fixed to the upper portion of the rod 16.

[0010] A structure of the stator 5 will now be described in detail with reference to the Fig. 11 to 16 explained.

[0011] As in Fig. 11, each of the lead wires 50 forming the coils 7 is formed by coating a copper wire 51 with an electrical insulating layer 52. As shown in Fig. 12, each of the coils 7 is constructed by winding the lead wires 50 with a predetermined number of turns into a bifilar winding (parallel winding) on ​​a lead wire coil portion 53a of the first and second coil cores 53A and 53B. In other words, the coils 7 are constructed by winding first and second lead wires 50a and 50b on each of the lead wire coil portions 53a together, side by side, into a ring-shaped form. Then, as shown in the Fig. 13 and Fig. 14, first to third coil terminals 8A, 8B, and 8C are attached to each of the first and second coil cores 53A and 53B, and the electrically insulating layer 52 is removed from one end of the winding start of the first lead wire 50A, and the winding start end of the first lead wire 50A is wound and soldered onto a fixing portion 8a of the first coil terminal 8A, the electrically insulating layer 52 is removed from one winding end of the second lead wire 50B, and the winding end of the second lead wire 50B is wound and soldered onto the fixing portion 8a of the third coil terminal 8C.and in addition, the electrical insulation layer 42 is removed from one winding end of the lead wire 50A, and both one end of the winding start of the lead wire 50B and the winding end of the lead wire 50A as well as the end of the winding start of the second lead wire 50B are wound and soldered onto the fixing portion 8a of the second coil terminal 8B.

[0012] As in Fig. 15, the coils 7 wound on the first and second coil cores 53A and 53B are embedded in an outer mold 54. Each of the coil terminals 8A, 8B, and 8C is folded and bent here, and the fixing portions 8a to which the end portions of the lead wires 50A and 50B are soldered are embedded in the outer mold 54. In addition, as shown in Fig. 16, the cores 55 made of iron are arranged to surround the coils 7 and complete the structure of the stator 5.

[0013] In the stepper motor 1 constructed in this way, as shown in Fig. As shown in Fig. 17, the coils 7 are formed by first-phase and second-phase excitation coils 7a and 7b connected in series, and third-phase and fourth-phase excitation coils 7c and 7d connected in series.A connecting portion M1 connecting the first-phase and second-phase excitation coils 7a and 7b, and a connecting portion M2 connecting the third-phase and fourth-phase excitation coils 7c and 7d are grounded, and a voltage of +14 V is applied between a terminal S1 of the first-phase excitation coil 7a and the connecting portion M1, a voltage of -14 V is applied between the connecting portion M1 and the terminal S2 of the second-phase excitation coil 7b, a voltage of +14 V is applied between a terminal S3 of the third-phase excitation coil 7c and the connecting portion M2, and a voltage of -14 V is applied between the connecting portion M2 and the terminal S4 of the fourth-phase excitation coil 7d. Moreover, the first lead wire 50A and the second lead wire 50B wound on the coil core 53A correspond to the first-phase and fourth-phase excitation coils, respectively.second phase 7a and 7b, and the first lead wire 50a and the second lead wire 50b wound on the second coil core 53b correspond to the third and fourth phase excitation coils 7c and 7d, respectively.

[0014] The stepping motor 1 is attached to, for example, a continuously variable automotive transmission, and the actuating member 22 attached to the upper portion of the rod 16 is engaged with a linkage 40 which opens and closes a transmission control valve in the continuously variable transmission.

[0015] When electrical power is supplied to the coil 7 through the external connector 25, the first-phase to fourth-phase excitation coils 7a to 7d are magnetized, and the rotor 6 and the shaft 4 are rotated together. The guide member 20 is engaged with the threaded portion 4a on the shaft 4, and since the rotation of the guide member 20 is regulated, the rotation of the shaft 4 is converted into a rectilinear motion of the guide member 20 and the rod 16.

[0016] The transmission control valve is opened and closed by means of the connection 40 by the reciprocating movement of the rod 16, which ultimately leads to the change in the rotational speed ratio between the drive shaft and the motor shaft.

[0017] The conventional stepping motor 1 is attached to a continuously variable automotive transmission and is completely immersed in the oil containing sulfur and organosulfur compounds, for example. Subsequently, the electrically insulating layer 42 is removed from the end portions of the lead wires 50A and 50B, and the end portions of the lead wires 50A and 50B are wound and soldered onto the attachment portions 8a of the coil terminals 8A, 8B, and 8C. Thus, the sulfur and organosulfur compounds in the oil penetrate the outer mold 54 and reach the soldered portions of the lead wires 50A and 50B. Since the electrically insulating layer 52 is removed from the end portions of the lead wires 50A and 50B, and the end portions of the lead wires 50A and 50B are wound and soldered onto the attachment portions 8a in a single layer, as shown in Fig. As shown in Figure 18, the amount of solder 56 in the soldered portions is small. For this reason, a chemical reaction of the sulfur and organosulfur compounds with the solder 56 occurs in the soldered portions, resulting in corrosion of the solder 56. One problem has been that the sulfur and organosulfur compounds reach the copper wire 51 due to the corrosion of the solder 56, and the copper wire 51 chemically reacts with the sulfur and organosulfur compounds and corrodes, ultimately leading to breakage of the lead wires 50A and 50B.However, if the amount of solder 56 is small, the copper wire 51 of the lead wires 50A and 50B is not completely embedded in the solder 56, resulting in a portion of the lead wire 51 being exposed, and therefore, another problem has been that a direct chemical reaction occurs between the exposed copper wire 51 and the sulfur and organosulfur compounds, resulting in corrosion of the copper wire 51 and breakage of the lead wires 50A and 50B.

[0018] The sulfur and organosulfur compounds in the oil penetrate the first and second coil cores 53A and 53B and the outer mold 54, and also penetrate the electrical insulating layer 52, and finally reach the copper wire 51. Subsequently, chemical reactions occur on the surface of the copper wire 51, and organosulfur compounds are formed on the surface of the copper wire 51, resulting in a decrease in the adhesive strength of the electrical insulating layer to the copper wire 51. In this state, damage to the electrical insulating layer occurs due to the interaction between adjacent lead wires 50a and 50b, which is caused by repeated thermal expansion and thermal contraction due to the heat generation of the lead wires 50A and 50B themselves.

[0019] In the conventional example, since the coil 7 is constructed by winding the lead wires 50A and 50B onto the lead wire coil portions 53a of the first and second coil cores 53A and 53B into a bifilar winding (parallel winding), the lead wires 50A and 50B, which have large electrical potential differences, are wound side by side. Yet another problem has been that when damage occurs in the electrically insulating layer 52, the chemical reactions between the copper wire 51 and the sulfur and organosulfur compounds are increased due to the large electrical potential differences between the lead wires 50A and 50B, causing the copper wire 51 to corrode and break.

[0020] EP 0 933 565 A2 discloses an actuator for actuating a control valve for changing the speed of an automatic speed changer. The actuator can be arranged within a gear housing, the housing accommodating a speed change mechanism and the control valve for changing the speed. Furthermore, DE 308 856 A discloses a method for connecting wires, wherein all wire ends to be connected are inserted from the bottom through matching openings into a solder sleeve, twisted together, and soldered together. GB 1 533 026 A discloses a rotor for an alternating current machine. DE 17 60 987 U describes a winding support with a protective sleeve. SUMMARY OF THE INVENTION

[0021] The present invention aims to solve the above problems, and one object of the present invention is to provide an electromagnetic device in which the wire breakage tolerance of a lead wire is improved. To achieve the above object, according to one aspect of the present invention, there is provided an electromotive device used in oil, the electromagnetic device comprising: an outer casing; a movable shaft supported by the outer casing; a coil core disposed within the outer housing such that the movable shaft is disposed on a common axis with the movable shaft; and a coil embedded in an outer mold, the coil is wound by winding a conductor wire in which a copper wire is coated with an electrical insulating layer, onto the coil core, wherein the electrical insulating layer is removed from an end portion of the conductor wire, and the end portion of the conductor wire is wound on a fixing portion of a coil terminal attached to the coil core to form a winding portion, a solder retaining member is mounted so as to cover the winding portion of the lead wire on the fixing portion, and the winding section of the lead wire is soldered to the fixing section together with the solder retaining part and leaves areas of the coil terminals uncovered, whereby the solder (56) is filled into the solder retaining part.

[0022] The solder holding member may have a cylindrical shape arranged to surround the wound portion of the lead wire.

[0023] The solder holding part may comprise a steel plate with applied solder.

[0024] The solder holding member may be a lead wire wound to overlap the wound portion of the lead wire.

[0025] The lead wire can be a copper wire with solder applied.

[0026] The end portion of the conductor wire from which the electrical insulating layer has been removed may be wound on the fixing portion in several layers.

[0027] Other features, objects and advantages of the present invention will become more apparent from the following description of the preferred embodiments with reference to the drawings, in which like reference characters indicate like or corresponding parts throughout the several views, of which: Fig. 1 is a cross-sectional view showing a stepping motor according to the first embodiment of the present invention; Fig. 2 is a front view of a coil core explaining a wound state of a coil in a stator of the stepping motor according to the first embodiment of the present invention; Fig. 3 a cross-sectional view along the line III-III in Fig. 2 is; Fig. 4 is a partial cross-sectional view showing a mounting portion of a coil core in a stator of a stepping motor according to the second embodiment of the present invention; Fig. 5 is a cross-sectional view showing a wound state of a coil in a stator of a stepping motor according to the third embodiment of the present invention; Fig. 6 is an external view of a conventional permanent magnet stepping motor; Fig. 7 a cross-sectional view along the line VII-VII in Fig. 6 is; Fig. 8 a cross-sectional view along the line VIII-VIII in Fig. 7 is; Fig. 9 a cross-sectional view along the line IX-IX in Fig. 7 is; Fig. 10 a perspective partially exploded view of the stepper motor in Fig. 7 is; Fig. 11 is a cross-sectional view showing a lead wire wound in a coil of the stepping motor in Fig. 7 is used; Fig. 12 is a cross-sectional view showing a wound state of the coil in a stator of the stepping motor in Fig. 7 explained; Fig. 13 is a front view of a coil core showing a wound state of the coil in the stator of the stepping motor in Fig. 7 explained; Fig. 14 is a perspective view showing the wound state of the coil in the stator of the stepping motor in Fig. 7 shows; Fig. 15 is a perspective view showing a molded state of a resin portion in the stator of the stepping motor in Fig. 7 shows; Fig. 16 is a perspective view showing the stator of the stepper motor in Fig. 7 shows; Fig. 17 is a diagram showing a coil structure of the stepper motor in Fig. 7 shows; and Fig. 18 is a partial cross-sectional view showing a fixing portion of a coil terminal in the stator of the stepping motor in Fig. 7 shows. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] The preferred embodiments of the present invention will now be explained with reference to the drawings. First embodiment

[0029] Fig. 1 is a cross-sectional view showing a stepping motor according to the first embodiment of the present invention, Fig. Fig. 2 is a front view showing a coil core on which a coil is wound in the stepping motor according to the first embodiment of the present invention, and Fig. 3 is a cross-sectional view taken along line III-III in Fig. 2. Moreover, in each of the figures, portions that are the same as or corresponding to those of the conventional electromagnetic device are designated by the same reference numerals, and explanation thereof is omitted here.

[0030] In Fig. 1, a motor main body 3 includes a stator 60 attached to an outer casing and a rotor 6 attached to a shaft 4. The stator 60 includes: coils 70, each constructed by winding a lead wire 50 having an electrically insulating layer formed on a surface of a copper wire 51; coil terminals 8 extending from the coils 70; connecting terminals 9 connected to the coil terminals 8; and an external connector 25 connected to the connecting terminals 9.

[0031] The rotor 6 has a sleeve 10 attached to the shaft 4 and a hollow cylindrical permanent magnet 11 magnetized in the circumferential direction and fitted over and attached to the sleeve 10.

[0032] The coils 70 are constructed by winding the conductive wire 50 with a predetermined number of turns into a unifilar winding (serial winding) on ​​a conductive wire coil portion 53a of the first and second coil cores 53A and 53B. In other words, the coils 70 are constructed by winding a first conductive wire 50A into an annular shape on each of the conductive wire coil portions 53a to form first-phase and third-phase excitation coils 70a and 70c, and then winding a second conductive wire 50b into an annular shape on top of the first-phase and third-phase excitation coils 70a and 70c on each of the conductive wire coil portions 53a to form second-phase and fourth-phase excitation coils 70b and 70d.Subsequently, the electrical insulating layer 52 is removed from one end of the winding start of the first conducting wire 5A, and the end of the winding start of the first conducting wire 50A is wound onto a fixing portion 8a of a first coil terminal 8a, the electrical insulating layer 52 is removed from one winding end of the second conducting wire 50B, and the winding end of the second conducting wire 50B is wound onto a fixing portion 8a of a third coil terminal 8c, and in addition, the electrical insulating layer 52 is removed from one winding end of the conducting wire 50A and one end of the winding start of the conducting wire 50B, and both the winding end of the first conducting wire 50A and the end of the winding start of the second conducting wire 50B are wound onto the fixing portion 8a of a second coil terminal 8b. In addition, as shown in FIGS. Fig. 2 and Fig. 3, a solder holding member 62 formed by folding and bending a steel plate with solder applied thereto into a cylindrical shape is attached to each of the attachment portions 8a of the first to third coil terminals 8A, 8B, and 8C, a solder 56 is filled into the solder holding member 62, and the winding portions of the lead wires 50A and 50B are soldered to the attachment portions 8a to thereby form soldered connecting portions.

[0033] The coils 70 wound on the first and second coil cores 53a and 53b are embedded in an outer mold 54. Here, each of the coil terminals 8A, 8B, and 8C is folded and bent, and the fixing portions 8a and the solder holding parts 62 to which the winding portions of the lead wires 50A and 50B are soldered are also embedded in the outer mold 54. In addition, the iron cores 55 are arranged to surround the coils 70, completing the construction of the stator 60. The stator 60 is arranged around the shaft 4 coaxially with the shaft 4.

[0034] Moreover, the rest of the structure is the same as in the above conventional stepper motor 1.

[0035] In a stepping motor 100, which is an electromagnetic device constructed in this manner, the electrical insulating layer 52 is removed from the end portions of the lead wires 50a and 50b constituting the coils 70, and the end portions of the lead wires 50A and 50B are wound onto each of the fixing portions 8a of the first to third coil terminals 8A, 8B, and 8C, the cylindrical solder holding members 62 are fixed so as to surround each of the fixing portions 8a, the solder 46 is filled into the solder holding members 62, and the winding portions of the lead wires 50A and 50B are soldered to each of the fixing portions 8a, thereby forming soldered connecting portions.The amount of solder 56 in each of the soldered connection portions is large, which prevents the copper wire 51 from being exposed, and the copper wire 51 is not corroded by direct chemical reaction with the sulfur and organosulfur compounds, thereby preventing the lead wire 50A and 50B from breaking.

[0036] The sulfur and organosulfur compounds chemically react with the solder 56 in the soldered joint portion, resulting in corrosion of the solder 56. However, since the amount of solder 56 is large, the sulfur and organosulfur compounds are unlikely to reach the copper wire 51 by corroding the solder 56. The occurrence of wire breakage of the lead wires 50A and 50B resulting from corrosion of the copper wire 51 caused by the chemical reaction of the copper wire 51 with the sulfur and organosulfur compounds is suppressed, resulting in an improvement in the wire breakage tolerance of the lead wires 50A and 50B.

[0037] Since the solder holding members 62 are made of the steel plate with solder applied thereto, when the solder 56 is filled into the solder holding members 62, the wettability of the solder holding member 62 with solder is good, and the solder 56 smoothly flows into the interior of the solder holding member 62, resulting in a large amount of solder 56 being held in the soldered connection portions (the winding portions 90). Since the exposure of the copper wire 51 resulting from solder corrosion 56 can be reliably prevented, and the sulfur and organosulfur compounds can no longer reach the copper wire 51, the wire breakage tolerance of the lead wires 50A and 50B can be further improved.

[0038] The sulfur and organosulfur compounds in the oil penetrate the first and second coil cores 53A and 53B and the outer mold 54, as well as the electrical insulating layer 52, and ultimately reach the copper wire 51 wound on the first and second coil cores 53A and 53B. Subsequently, a chemical reaction occurs on the surface of the copper wire 51, and organosulfur compounds are formed on the surface of the copper wire 51, resulting in a reduced bond strength of the electrical insulating layer to the copper wire 51. In this state, damage to the electrical insulating layer occurs due to the interaction between adjacent lead wires 50a and 50b caused by repeated thermal expansion and thermal contraction due to the heat generation of the lead wire 50a and 50b itself.

[0039] In this stepping motor 100, the coils 70 are constructed by winding the first lead wire 50A on the lead wire coil portion 53a of the first and second coil cores 53A and 53B to form first-phase and third-phase excitation coils 70a and 70c, and additionally by winding the second lead wire 50B on top of the first-phase and third-phase excitation coils 70a and 70c to form second-phase and fourth-phase excitation coils 70b and 70d. In other words, the coils 70 are constructed by winding the first and second lead wires 50A and 50B into a unifilar winding (series winding) on ​​the lead wire coil portions 53a.The first-phase excitation coil 70a (the third-phase excitation coil 70c) and the second-phase excitation coil 70b (the fourth-phase excitation coil 70d) are wound so as to be laminated in two layers on the lead wire coil portions 52, and the lead wires 50A and 50B, which have large electrical potential differences, are no longer adjacent to each other. Thus, even if damage occurs in the electrically insulating layer 52, the chemical reaction between the copper wire 51 and the sulfur and sulfur compounds is not further increased due to the large electrical potential differences between the lead wires 50A and 50B, thereby suppressing corrosion of the copper wire 51 and improving the wire breakage tolerance of the lead wires 50A and 50B. Second embodiment

[0040] In the second embodiment, as in Fig. 4, the electrical insulation layer 52 is removed from the end portions of the lead wires 50A (50B), and the end portions of the lead wires 50A (50B) are wound on the fixing portions 8a of each of the first and third coil terminals 8A (8B and 8C) in one layer, a lead wire 63 consisting of a copper wire with solder applied thereto and acting as a solder holding member is additionally wound on the top of each of the lead wires 50A (50B) in three layers, and the solder 56 is applied to the wound portions of the lead wires 50A (50B) and the lead wires 63, thereby soldering each of the lead wires 50A (50B) and the lead wires 63 to the fixing portions 8a.

[0041] Moreover, the remaining part of the structure is similar to the above of the first embodiment.

[0042] According to the second embodiment, the solder 56 seeps into the winding portions of the lead wires 50A (50B) and the lead wires 63 due to capillary action, thereby allowing a large amount of solder to be held in the soldered connection portions (winding portions 91). Furthermore, since the lead wire 63 is made of the copper wire with solder deposited thereon, the wettability of the lead wire 63 with solder is improved, resulting in an increase in the amount of solder held in the soldered connection portion. Consequently, similar effects to those in the first embodiment can also be achieved in the second embodiment. Third embodiment

[0043] In the third embodiment, as shown in the Fig.5, the lead wire coil portions 59 of the first and second coil cores 58A and 58B are divided into first and second divided coil portions 59a and 59b in the axial direction of the shaft 4, the first lead wire 50A of the coils 70A is wound on the first and second divided coil portions 59a of the first and second coil cores 58A and 58B to form first-phase and third-phase excitation coils 70a and 70c, and in addition, the second lead wire 50B is wound on the divided coil portions 59b to form the second-phase and fourth-phase excitation coils 70b and 70d. In other words, the coil 70A is formed by winding the lead wires 50A and 50B into a unifilar winding (serial winding) on ​​the lead wire coil portions 59.

[0044] Moreover, the remaining structure is similar to that of the first embodiment above.

[0045] According to the third embodiment, since the lead wires 50A and 50B, which have large electrical potential differences, are separated in the axial direction and wound on the lead wire coil portions 59, even if damage occurs in the electrical insulating layer 52, the chemical reaction between the copper wire 51 and the sulfur and organosulfur compounds is not promoted due to the large electrical potential differences between the lead wires 50A and 50B, thereby suppressing the corrosion of the copper wire 51 and improving a wire breakage tolerance of the lead wires 50A and 50B.

[0046] Moreover, as in each of the above embodiments, the lead wires 50A and 50B are wound on the fixing portions 8a in a single layer, but the lead wires 50A and 50B may be wound on the fixing portions 8a in multiple layers. In this case, the solder 56 seeps into the winding portions of the lead wires due to capillary action, thereby retaining a large amount of solder in the winding portions of the lead wires and improving the wire breakage tolerance.

[0047] In the above first embodiment, the solder-coated steel plate formed by folding and bending into a cylindrical shape is used as the solder retaining member 62. However, the shape of the solder retaining member is not limited to a cylindrical shape, but may also be an elliptical shape or a C-shape. Furthermore, the material for the solder retaining member is not limited to the solder-coated steel plate, but may also be a ceramic material or a metal.

[0048] In each of the above embodiments, there is no particular limitation on the material for the solder 56. Wire breakage tolerance can be further improved when high-lead (60 wt% or more of lead) solder is used.

[0049] Each of the above embodiments has been explained with reference to stepper motors. However, the present invention is not limited to stepper motors, but can be applied to any electromagnetic device used in oil, such as a solenoid valve for controlling the action or movement of a gear mechanism for adjusting the rotational speed ratio between a drive shaft and a motor shaft by regulating an oil passage using a movable valve to control the oil flow rate or pressure.

[0050] Although the preferred embodiments of the present invention have been described above, it should be understood that the present invention is not limited thereto, but that other modifications will be apparent to those skilled in the art without departing from the spirit of the invention.

[0051] The scope of the invention should therefore be determined solely by the appended claims.

[0052] This electromagnetic device of the present invention is configured as described above. The electromagnetic device can thus achieve the following effects.

[0053] According to one aspect of the present invention, there is provided an electromotive device used in oil, the electromagnetic device comprising: an outer casing; a movable shaft supported by the outer casing; a coil core disposed within the outer casing so as to be arranged around the movable shaft on a common axis with the movable shaft; and a coil embedded in an outer mold, the coil being constructed by winding a lead wire in which a copper wire is coated with an electrical insulating layer onto the coil core, wherein the electrical insulating layer is removed from an end portion of the conductor wire, and the end portion of the conductor wire is wound on a fixing portion of a coil terminal attached to the coil core so as to form a winding portion, a solder holding member is fixed so as to cover the winding portion of the lead wire on the fixing portion, and the winding portion of the lead wire is soldered to the fixing portion together with the solder retaining member, thereby preventing wire breakage resulting from sulfur and organosulfur compounds in the oil corroding the solder and reaching the copper wire, and an electromagnetic device is provided which enables wire breakage tolerance in the lead wire to be improved.

[0054] The solder retaining member may have a cylindrical shape arranged to surround the winding portion of the lead wire, thereby allowing a large amount of solder to be retained in the winding portion and thereby precluding exposure of the lead wire, further preventing the sulfur and organosulfur compounds from reaching the copper wire due to corrosion of the solder.

[0055] The solder retaining member may comprise a steel plate with solder deposited thereon, thereby improving the wettability with solder and increasing the amount of solder retained in the winding portion.

[0056] The solder retaining member may be a lead wire wound so as to overlap the winding portion of the lead wire, whereby the solder seeps into the winding portion due to capillary action, and the amount of solder retained in the winding portion is increased.

[0057] The lead wire may be a copper wire with solder deposited thereon, resulting in improved wettability with solder and increasing the amount of solder retained in the winding portion.

[0058] The end portion of the lead wire from which the electrical insulation layer is removed may be wound in multiple layers on the fixing portion, whereby the solder infiltrates into the winding portion due to capillary action, and the amount of solder retained in the winding portion is increased.

[0059] According to a further aspect of the present invention, there is provided an electromotive device used in oil, the electromagnetic device comprising: an outer casing; a movable shaft supported by the outer casing; a coil core disposed within the outer casing so as to be arranged around the movable shaft on a common axis with the movable shaft; and a coil embedded in an outer mold, and the coil is wound on the coil core by winding a conductor wire in which a copper wire is coated with an electrical insulating layer, wherein the coil core is formed by first and second coil cores arranged in the axial direction of the movable shaft, and the coil is constructed by first-phase and second-phase excitation coils formed by winding two conducting wire strands into a unifilar winding on a conducting wire coil portion of the first coil core, and third-phase and fourth-phase excitation coils wound by winding two conducting wire strands into a unifilar winding on a conducting wire coil portion of the second coil core.

[0060] Even if the sulfur and organosulfur compounds in the oil penetrate the electrical insulating layer, reach the copper wire, and chemically react with the copper wire, resulting in reduced adhesive strength of the electrical insulating layer and damage to the electrical insulating layer, and since the first-phase and third-phase excitation coils and the second-phase and third-phase excitation coils, which have large electrical potential differences, are not adjacent, chemical reactions between the lead wire and the organosulfur compounds are not increased, preventing wire breakage resulting from corrosion of the copper wire, and thereby achieving an electromagnetic device that enables wire breakage tolerance in the lead wire to be improved.

[0061] The first-phase excitation coil may be constructed by winding one strand of conductive wire with a predetermined number of turns on a bottom surface side of the coil portion of the first coil core, and the second-phase excitation coil may be constructed by winding the other strand of conductive wire with a predetermined number of turns on the conductive wire coil portion of the first coil core such that it overlaps the first-phase excitation coil, and the third-phase excitation coil may be constructed by winding one strand of conductive wire with a predetermined number of turns on a bottom surface side of the conductive wire coil portion of the second coil core, and the fourth-phase excitation coil may be constructed by winding the other strand of conductive wire with a predetermined number of turns on the conductive wire coil portion of the second coil core such that it overlaps the third-phase excitation coil,be constructed in a way that ensures a sufficient distance between the first-phase and third-phase excitation coils and the second-phase and third-phase excitation coils, which have large electrical potential differences, and chemical reactions between the copper wire and the sulfur and organosulfur compounds are not increased, which leads to a suppression of corrosion of the copper wire.

[0062] The conducting wire coil portions of the first and second coil cores may be divided into two divided coil portions in the axial direction of the movable shaft, and the first-phase to fourth-phase excitation coils may be constructed by winding a conducting wire strand on each of the divided coil portions of the conducting wire coil portions of the first and second coil cores, which ensures a sufficient distance between the first-phase and third-phase excitation coils and the second-phase and third-phase excitation coils having large electrical potential differences, whereby chemical reactions between the copper wire and the sulfur and organosulfur compounds are not increased, resulting in suppression of corrosion of the copper wire.

Claims

[1] An electromagnetic device used in an oil, the electromagnetic device comprising: an outer casing (2); a movable shaft (4) supported by the outer casing (2); a coil core (53A, 53B, 58A, 58B) arranged within the outer casing (2) such that the movable shaft (4) is arranged on a common axis with the movable shaft; and a coil (70, 70A) embedded in an outer mold (54), the coil (70, 70A) being constructed by winding a conductor wire (50, 50A, 50B), in which a copper wire (51) is coated with an electrical insulating layer (52), onto the coil core (53A, 53B, 58A, 58B), wherein the electrical insulating layer (52) is removed from an end portion of the conducting wire (50, 50A, 50B), and the end portion of the conducting wire (50, 50A, 50B) is wound onto a fixing portion (8a) of a coil terminal (8, 8A, 8B, 8C) attached to the coil core (53A, 53B, 58A, 58B) to form a winding portion (90, 91), a solder retaining member (62, 63) is mounted such that it covers the winding portion (90, 91) of the lead wire (50, 50A, 50B) on the fixing portion (8a) and leaves portions of the coil terminals (8, 8A, 8B, 8C) uncovered, and the winding portion (90, 91) of the lead wire (50, 50A, 50B) is soldered to the fixing portion (8a) together with the solder retaining member (62, 63), wherein the solder (56) is filled into the solder retaining part (62, 63). [2] The electromagnetic device according to claim 1, wherein the solder retaining member (62) has a cylindrical shape and is arranged to surround the winding portion (90) of the lead wire. [3] The electromagnetic device according to claim 2, wherein the solder retaining member (62) comprises a steel plate with solder applied thereto. [4] The electromagnetic device according to claim 1, wherein the solder retaining member (63) is a lead wire wound so as to overlap the winding portion (91) of the lead wire. [5] The electromagnetic device according to claim 4, wherein the lead wire (63) is a copper wire with solder applied thereto. [6] The electromagnetic device according to any one of claims 1 to 5, wherein the end portion of the conductive wire (50, 50A, 50B) from which the electrical insulating layer (52) is removed is wound on the fixing portion (8a) in multiple layers.

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