JP4437857B2 - Coreless motor for electric power steering - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a coreless motor for electric power steering.
[0002]
[Prior art]
As a coreless motor for electric power steering, for example, Japanese Utility Model Publication No. 3-52606 “Electric Boost Steering Device” is known.
According to the drawing of the above publication, the worm 6 (ball screw) is formed on the rack shaft 4 (axle), the nut 7 is engaged with the ball screw, and the armature winding 12 (winding) Wire cylinder), the commutator 13 is attached to the nut 7, and the commutator 13 is pressed from the circumferential direction of the commutator 13 by the slider 14 (brush) housed in the holder 15, and the armature winding 12 An electric power in which magnets 16 (permanent magnets) are arranged inward and support the magnets 16 and the slider 14, and the nut 7, the armature winding 12, and the commutator 13 are covered with the rack housing 3 (motor housing). This is a coreless motor for steering.
[0003]
[Problems to be solved by the invention]
However, the coreless motor for electric power steering has a structure in which the armature winding 12 is rotated in the space sealed by the rack housing 3 and the commutator 13 is brought into contact with the commutator 13. Heat generation of the slider 14 cannot be avoided, and the life of the coreless motor may be reduced.
For example, in order to avoid heat generation of the commutator 13 and the slider 14, if a heat radiating hole or the like is opened in the rack housing 3, dust, mud or the like enters the rack housing 3, which may cause a failure of the coreless motor. Become.
[0004]
Accordingly, an object of the present invention is to provide a coreless motor for electric power steering capable of preventing heat generation of a commutator and a brush without opening a heat radiating hole or the like in the motor housing.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a first aspect of the present invention provides a ball screw formed on an axle, a nut meshed with the ball screw, a cylinder attached to the nut, a holding disk provided on the cylinder, A winding cylinder having one end fitted to the outer peripheral portion of the holding disk, a commutator attached to the holding disk, a brush pressing the commutator, a permanent magnet disposed inside the winding cylinder, and a permanent magnet In a coreless motor for electric power steering, which supports a magnet and a brush, and includes a nut, a holding disk, a winding cylinder, and a motor housing that covers a commutator, a through hole that is substantially parallel to the axle is opened in the holding disk, and the axle is and opened substantially parallel holes in the radial axis from the center, the air was through the end surface of the brush toward the axial direction of the axle from the through hole of the holding disk, toward the radial axis of the axle Cormorant is through the end face of the brush, characterized in that air is directed into the cylindrical body through holes to generate a circulating flow in the circulation flow, or vice versa circulating.
[0006]
A through hole is formed in the holding disk substantially parallel to the axle, a through hole is formed in the cylinder from the center of the axle and substantially parallel to the radial axis, and an end face of the brush that directs air from the through hole of the holding disk in the axial direction of the axle. is over, by way of the end face of the brush toward the radial axis of the axle, in Rukoto to generate a circulating flow or reverse circulation flow that circulates by directing air to the cylindrical body through holes, heat generation of the commutator and brushes Control
[0007]
According to a second aspect of the present invention, the through hole of the holding disk is a hole inclined at a predetermined angle with respect to the axle.
By tilting the through hole of the holding disk at a predetermined angle with respect to the axle, air is actively circulated in the motor housing.
[0008]
According to a third aspect of the present invention, the through hole of the cylindrical body is a hole inclined at a predetermined angle with respect to the radial axis.
By inclining the through hole of the cylindrical body at a predetermined angle with respect to the radial axis, air is actively circulated in the motor housing.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings. The drawings are viewed in the direction of the reference numerals.
FIG. 1 is a perspective view of a steering apparatus equipped with a coreless motor for electric power steering according to the present invention.
A steering device 10 as an electric power steering is an example of an electric power steering provided with a coreless motor 30 for electric power steering (hereinafter abbreviated as “coreless motor”) that assists the steering force of the steering wheel 11. 11 is detected by a torque sensor 12, and a controller 13 for controlling the coreless motor 30 based on information from the torque sensor 12 is provided.
[0010]
In the figure, 14 is a battery, 15 is a steering shaft for supporting the steering wheel 11, 16 is a universal joint attached to the tip of the steering shaft, 17 is a tip shaft attached to the steering shaft 15 via the universal joint 16, and 18 is a gear case. , 19 is an axle, 21 and 21 are tie rods attached to the axle 19, and 22 and 22 are front wheels.
[0011]
FIG. 2 is a cross-sectional view of a main part of a steering device equipped with a coreless motor for electric power steering.
Specifically, the steering device 10 houses a pinion 24 formed on the tip shaft 17 and a rack 25 formed on the axle 19 in the gear case 18, and transmits the rotation of the pinion 24 to the rack 25, thereby moving the axle 19 left and right in the drawing. At this time, the rotational torque of the coreless motor 30 is transmitted to the ball screw 26 formed on the axle 19 via the thrust ball group 27 which is a power transmission member, whereby the steering wheel 11 ( The steering force of FIG. 1) is assisted. Reference numerals 28 and 28 denote ball joints for connecting the tie rods 21 and 21 to the axle 19, and 29 denotes a nut fitted to the ball screw 26 via a thrust ball group 27.
[0012]
FIG. 3 is a front sectional view of the coreless motor for electric power steering according to the present invention.
The coreless motor 30 includes a ball screw 26 formed on the axle 19, a nut 29 meshed with the ball screw 26, a cylinder 46 attached to the nut 29, a holding disk 43 provided on the cylinder 46, A winding cylinder 44 having one end 44 a fitted to the outer peripheral portion 43 b of the holding disk 43, a commutator 42 attached to the holding disk 43, brushes 38 and 38 that press the commutator 42, and the winding cylinder 44 In a coreless motor constituted by a permanent magnet 34 disposed inward and a motor housing 35 that supports the permanent magnet 34 and brushes 38 and 38 and covers a nut 29, a holding disk 43, a winding cylinder 44, and a commutator 42. The through hole 47 (... indicates a plurality, the same applies hereinafter) that is substantially parallel to the axle 19 is formed in the holding disk 43, and the cylindrical body 46. A through hole 49... Is formed from the center of the axle 19 and substantially parallel to the radial axis, and air is circulated in the motor housing 35 through these through holes 47. . The nut 29 is provided in the vicinity of the holding disk 43.
[0013]
4 is an exploded perspective view of the stator of the coreless motor for electric power steering according to the present invention. The stator 31 has a ball bearing 33 attached to one end 32a of the fixing member 32 and a permanent attachment attached to the outer periphery 32b of the fixing member 32. A magnet 34, a motor housing 35 that houses the permanent magnet 34, the ball bearing 33 and the fixing member 32, a ball bearing 36 attached to the gear case 18 side, a brush attachment base 37 attached to the gear case 18 side, and the brush The brushes 38 are attached to the attachment base 37. Reference numeral 18 a denotes a flange portion of the gear case, and reference numeral 35 a denotes an edge portion 35 a of the motor housing 35.
[0014]
FIG. 5 is an exploded perspective view of the rotor of the coreless motor for electric power steering according to the present invention. The rotor 41 has a commutator 42 attached to a holding disk 43 and the holding disk 43 is fitted to one end 44 a of the winding cylinder 44. Then, a thrust ring 45 is fitted to the other end 44b of the winding cylinder 44, a cylinder 46 is fitted to the holding disk 43, and a ball is inserted into the cylinder 46 via the thrust ball group 27 shown in FIG. A nut 29 to be fitted to the screw 26 is attached. The nut 29 is provided in the vicinity of the holding disk 43.
The commutator 42 is a set of commutator pieces 42 a... Arranged in a disk shape on one side surface 43 a of the holding disk 43, and a relief hole 48 to be fitted into the plurality of through holes 47. Is provided.
[0015]
6 is a view taken along line 6-6 in FIG. 3 and shows one side surface 43a of the holding disk 43. FIG.
The holding disk 43 is a disk-like member that supports one end 44a of the winding cylinder 44 and holds the commutator pieces 42a (see FIG. 5), and has a plurality of through holes 47. It is a member. Reference numeral 43 b denotes an outer peripheral portion of the holding disk 43.
[0016]
7 is a cross-sectional view taken along line 7-7 of FIG. 6. The through hole 47 is formed on one side surface 43a of the holding disk 43 and is formed obliquely in the circumferential direction of the holding disk 43, whereby the rotor 41 (FIG. The air flow is intended to be generated by the rotation of (see).
That is, the coreless motor 30 (see FIG. 3) actively inclines air into the motor housing 35 (see FIG. 3) by inclining the through holes 47... To try to circulate. As a result, the cooling effect of the commutator 42 and the brushes 38 and 38 shown in FIG. 3 can be improved.
[0017]
8 is a cross-sectional view taken along the line 8-8 in FIG. 3, and the cylindrical body 46 transmits the rotational torque of the coreless motor 30 to the ball screw 26 formed on the axle 19 through the thrust ball group 27 as shown in FIG. And a through-hole 49 formed so as to be inclined with respect to the radial axis A toward the axle 19 from the outer periphery of the cylindrical body 46.
That is, the coreless motor 30 (see FIG. 3) actively inclines air into the motor housing 35 (see FIG. 3) by inclining the through holes 49... It is intended to be circulated inside. As a result, the cooling effect of the commutator 42 and the brushes 38 and 38 shown in FIG. 3 can be improved.
[0018]
Next, the operation of the coreless motor 30 described above will be described. 9 to 12 are process diagrams showing an example of the assembly procedure of the coreless motor 30. First, the assembly procedure of the coreless motor 30 will be described.
9A and 9B are first assembly process diagrams of the coreless motor for electric power steering according to the present invention. In FIG. 9A, a ball bearing 33 is attached to one end 32a of the fixing member 32, and the fixing member 32 is fixed. Permanent magnets 34 are attached to the outer periphery 32 b of the motor, and the permanent magnets 34, the ball bearings 33, and the fixing member 32 are accommodated in the motor housing 35.
That is, in (b), the stator subassembly 51 is made by assembling the fixing member 32, the ball bearing 33, and the permanent magnet 34 to the motor housing 35 from the axle direction.
[0019]
10 (a) and 10 (b) are second assembly process diagrams of the coreless motor for electric power steering according to the present invention. In FIG. 10 (a), the commutator 42 is attached to the holding disk 43, and the holding disk 43 is wound. The wire cylinder 44 is fitted to one end 44 a, and the thrust ring 45 is fitted to the other end 44 b of the winding cylinder 44.
That is, in (b), the commutator 42, the holding disk 43, and the thrust ring 45 are assembled to the winding cylinder 44 from the axle direction to form the rotor subassembly 52.
[0020]
11 (a) and 11 (b) are third assembly process diagrams of the coreless motor for electric power steering according to the present invention. In FIG. 11 (a), the ball screw 26 is passed through the gear case 18 and the rotor 41 (see FIG. 3). ) Side nut 46 is fitted to the nut 46, the nut 29 is fitted to the ball screw 26 via the thrust ball group 27 (see FIG. 3), and a ball bearing 36 is attached to the gear case 18. The brush mounting base 37 to which the brushes 38 are already mounted is mounted on the flange portion 18a.
That is, in (b), the gear case sub-assembly 53 is obtained by attaching the ball bearing 36, the cylindrical body 46, the nut 29, the brush attachment base 37, and the brushes 38, 38 from the axle direction to the gear case 18 through which the ball screw 26 is passed. To.
[0021]
FIG. 12 is a fourth assembly process diagram of the coreless motor for electric power steering according to the present invention. The rotor subassembly 52 is assembled to the gear case subassembly 53 from the axle direction, and the rotor subassembly 52 and the gear case subassembly are assembled. The stator subassembly 51 is assembled to the axle 53 in the axle direction, and the edge portion 35a of the motor housing 35 is caulked to the flange portion 18a of the gear case 18 to complete the assembly of the coreless motor 30.
That is, the commutator 42 is attached to one side surface 43a of the holding disk 43, and the commutator 42 is pressed by the brushes 38, 38 from the axle direction, so that all the components of the coreless motor 30 are assembled along the axle 19. be able to. As a result, the assemblability of the coreless motor 30 can be improved, and the manufacturing cost of the coreless motor 30 can be reduced by reducing the assembling time.
[0022]
FIGS. 13A and 13B are first operation explanatory views of the coreless motor for electric power steering according to the present invention. FIG. 13A shows a comparative example, and FIG. 13B shows an example.
In (a), in the coreless motor 100 of the comparative example, a commutator 101 is provided along an axle 102, brushes 103, 103 are disposed around the commutator 101, and the commutator 101 is mounted on the axle 102 with the brushes 103, 103. The nut 107 for transmitting the rotational torque of the coreless motor 100 to the ball screw 105 formed on the axle 102 is provided on the thrust ring 109 side facing the holding disk 108. And the overall length of the coreless motor 100 is long. Here, the total length of the coreless motor 100 is referred to as L1.
[0023]
In (b), in the coreless motor 30 of the embodiment, a holding disk 43 is fitted to one end 44 a of the winding cylinder 44, and a nut 29 is disposed in the vicinity of the holding disk 43 and in the cylindrical body 46. Is engaged with the ball screw 26, so that the total length of the coreless motor 30 can be shortened. Further, by attaching a commutator 42 to one side 43a of the holding disk 43 and pressing the commutator 42 with brushes 38 from the axle direction, the overall length of the coreless motor 30 can be further shortened. Here, if the total length of the coreless motor 30 is L2, the total length L2 is shorter than the total length L1 of the coreless motor 100 shown in (a) (L2 <L1).
[0024]
That is, the outer peripheral portion 43 b of the holding disk 43 is fitted to one end of the winding cylinder 44, the nut 29 is disposed in the vicinity of the holding disk 43 and on the cylindrical body 46, and the nut 29 is engaged with the ball screw 26. By doing so, the overall length of the coreless motor 30 is shortened. That is, the coreless motor 30 can be a compact motor.
[0025]
FIGS. 14A and 14B are explanatory views of a second action of the coreless motor for electric power steering according to the present invention.
In (a), when the rotor 41 is rotated clockwise as indicated by the arrow (1), an air flow from the inside to the outside is generated in the through hole 49 of the cylindrical body 46 as indicated by the arrow (2). As shown by the arrow (3), an air flow from the front side of the drawing to the back side of the drawing is generated in the through hole 47 of 43. As a result, in (b), a circulating flow 54 is generated between the through hole 47 of the holding disk 43 and the through hole 49 of the cylindrical body 46. Thereby, the frictional heat generated between the commutator 42 and the brushes 38 can be cooled. As a result, the life of the coreless motor 30 (see FIG. 3) can be extended.
[0026]
FIGS. 15A and 15B are explanatory views of a third action of the coreless motor for electric power steering according to the present invention.
In (a), when the rotor 41 is rotated counterclockwise as indicated by an arrow (4), an air flow from the outside to the inside is generated in the through hole 49 of the cylindrical body 46 as indicated by an arrow (5). In the through hole 47 of the disk 43, an air flow is generated from the back side of the drawing toward the front side of the drawing as indicated by an arrow (6). As a result, in (b), a circulating flow 55 opposite to the circulating flow 54 shown in FIG. 14 is generated between the through hole 47 of the holding disk 43 and the through hole 49 of the cylindrical body 46 as indicated by the arrow. Thereby, the frictional heat generated between the commutator 42 and the brushes 38 can be cooled.
[0027]
In the embodiment, as shown in FIG. 3, a commutator 42 is provided on one side 43 a of the holding disk 43, that is, outside the winding cylinder 44, and the brushes 38 are pressed against the commutator 42. However, the present invention is not limited to this, and a commutator may be provided inside the winding cylinder and a brush may be pressed against the commutator.
Further, in the embodiment, as shown in FIG. 3, the nut 29 is provided on the holding disk 43 side and the rotational torque is transmitted to the ball screw 26. However, the present invention is not limited to this. What is necessary is just to provide in arbitrary positions.
Furthermore, in the embodiment, as shown in FIG. 3, a commutator is attached to one side surface of the holding disk, and the commutator 42 is pressed by the brushes 38, 38 from the axle direction, but is not limited thereto. A commutator may be provided along the axle, a brush may be disposed around the commutator, and the commutator may be pressed with the brush along the radial axis of the axle.
[0028]
【The invention's effect】
The present invention exhibits the following effects by the above configuration.
According to the first aspect of the present invention, the holding disk has a through hole substantially parallel to the axle, the cylinder has a through hole from the center of the axle and substantially parallel to the radial axis, and air is passed through the holding disk through the axial direction of the axle. Since a circulating flow that circulates by directing air to the through hole of the cylinder through the end surface of the brush that goes to the radial axis of the axle and vice versa is generated , the commutator And heat generation of the brush can be prevented. As a result, the life of the coreless motor for electric power steering can be extended.
[0029]
According to the second aspect of the invention, since the through hole of the holding disk is inclined at a predetermined angle with respect to the axle, air can be actively circulated in the motor housing. As a result, the cooling effect of the commutator and the brush can be improved.
[0030]
According to the third aspect of the present invention, since the through hole of the cylindrical body is inclined at a predetermined angle with respect to the radial axis, air can be actively circulated in the motor housing. As a result, the cooling effect of the commutator and the brush can be improved.
[Brief description of the drawings]
FIG. 1 is a perspective view of a steering device equipped with a coreless motor for electric power steering according to the present invention. FIG. 2 is a cross-sectional view of the main part of a steering device equipped with a coreless motor for electric power steering. FIG. 4 is an exploded perspective view of a stator of a coreless motor for electric power steering according to the present invention. FIG. 5 is an exploded perspective view of a rotor of a coreless motor for electric power steering according to the present invention. 6 is a sectional view taken along line 6-6 in FIG. 3. FIG. 7 is a sectional view taken along line 7-7 in FIG. 6. FIG. 8 is a sectional view taken along line 8-8 in FIG. FIG. 10 is a first assembly process diagram of the coreless motor for steering. FIG. 10 is a second assembly process diagram of the coreless motor for electric power steering according to the present invention. -Third assembly process diagram of the coreless motor for steering [Fig. 12] Fourth assembly process diagram of the coreless motor for electric power steering according to the present invention [Fig. 13] First operation of the coreless motor for electric power steering according to the present invention FIG. 14 is a diagram illustrating a second action of the coreless motor for electric power steering according to the present invention. FIG. 15 is a diagram illustrating a third action of the coreless motor for electric power steering according to the present invention.
DESCRIPTION OF SYMBOLS 19 ... Axle, 26 ... Ball screw, 29 ... Nut, 30 ... Coreless motor, 34 ... Permanent magnet, 35 ... Motor housing, 38 ... Brush, 42 ... Commutator, 43 ... Holding disk, 43b ... Outer peripheral part, 44 ... Winding Wire cylinder 44a ... one end, 46 ... cylindrical body, 47 ... holding disk through hole, 49 ... cylindrical body through hole, A ... radial axis.

Claims (3)

A ball screw (26) formed on the axle (19) , a nut (29) meshed with the ball screw (26) , a cylinder (46) attached to the nut (29) , and the cylinder (46 a disk (43) retained provided on), the commutator (42 outer peripheral portion (fitting at one end to 43 b) combined winding cylinder (44), attached to the holding disc (43) of the holding disc (43) ) , A brush (38 ) for pressing the commutator (42) , a permanent magnet (34) disposed inside the winding cylinder (44) , and these permanent magnet (34) and brush (38). A coreless motor for electric power steering comprising a nut (29) , a holding disk (43) , a winding cylinder (44) , and a motor housing (35) covering the commutator (42) ,
A through hole (47) substantially parallel to the axle (19) is formed in the holding disk (43) , and a through hole (49) substantially parallel to the radial axis is formed in the cylindrical body (46) from the center of the axle (19 ). Open
The brush (38) that passes air from the through hole (47) of the holding disk (43) through the end surface of the brush (38) that goes in the axial direction of the axle (19) and goes to the radial axis of the axle (19). A coreless motor for electric power steering, characterized in that a circulating flow that circulates through the end face of the cylinder and directs air to the through hole (49) of the cylindrical body (46) or vice versa is generated . The coreless motor for electric power steering according to claim 1, wherein the through hole (47) of the holding disk (43) is a hole inclined at a predetermined angle with respect to the axle (19) . 3. The electric power steering according to claim 1, wherein the through hole (49) of the cylindrical body (46) is a hole inclined at a predetermined angle with respect to the radial axis (A) . Coreless motor.

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