JP2022176785A - motor - Google Patents

Abstract

To provide a motor, having a cover bonded to a case with an adhesive, which can improve corrosion resistance against water that enters from an adhesive coating part.SOLUTION: A case 30 is made of metal, and has a cylinder part 31 and a bottom part 37. The case has an opening on the side opposite to the bottom part 37, and the case houses a stator 50 and a rotor 60. A fixed part outer wall 22 of a rear frame 20 is fixed by interference-fitting to an intermediate part inner wall 32 of the cylinder part 31 of the case 30. At a position further on the opening side of the case 30 than the fixed part outer wall 22, a groove forming outer wall 27 forms an annular groove part 34 between itself and an opening inner wall 33 of the case 30. A cover 40 is provided so as to cover the opening of the case 30, and an edge 44 is inserted into the annular groove part 34 filled with an adhesive Ad so that the cover is bonded to the case 30. An anti-corrosion ring 70 has corrosion resistance and is fitted to the opening inner wall 33 of the case 30 by interference-fitting inside the annular groove part 34.SELECTED DRAWING: Figure 2

Description

The present invention relates to motors.

2. Description of the Related Art Conventionally, a motor using an adhesive as a sealing means for liquid-tightly sealing a motor case containing a stator and a cover covering an opening of the motor case is known.

For example, Patent Literature 1 discloses a driving device that is applied to a rack-mounted electric power steering device and in which a motor section and a control section that controls energization of the motor section are integrally configured. In this driving device, an annular protrusion formed on the end surface of the peripheral wall of the control unit cover fits into the adhesive groove of the motor case, thereby ensuring waterproofness between the control unit cover and the motor case. A controller cover is joined to the motor case.

Japanese Patent No. 6160585

Although a certain degree of waterproofing effect can be obtained by applying adhesive, in an environment where water splashes violently, water may enter the inside from the adhesive-applied part and cause corrosion. Patent Literature 1 does not mention prevention of corrosion due to intrusion of water.

The present invention has been created in view of such points, and its object is to improve the corrosion resistance against water intrusion from the adhesive-applied portion in a motor in which the cover is bonded to the case with an adhesive. is to provide

The motor according to the invention comprises a case (30), a rear frame (20), a cover (40) and a corrosion resistant ring (70). The case is made of metal, has a cylindrical portion (31) and a bottom portion (37), is open on the opposite side of the bottom portion, and accommodates a stator (50) and a rotor (60).

The rear frame has a fixed part outer wall (22) and a grooved outer wall (27). The fixed part outer wall is fixed with an interference fit to the intermediate inner wall (32) of the case barrel. The groove-forming outer wall forms an annular groove (34) between itself and the inner wall (33) of the opening of the case on the opening side of the case with respect to the outer wall of the fixed part. The cover is provided so as to cover the opening of the case, and is joined to the case by inserting the rim (44) into an annular groove filled with an adhesive (Ad).

The corrosion-resistant ring is corrosion-resistant and is attached to the inner wall of the opening of the case in the annular groove with an interference fit. In addition, "interference fitting" includes press fitting, shrink fitting and cooling fitting. By observing or analyzing the finished motor, one skilled in the art can identify that the corrosion resistant ring is secured to the case with an interference fit. Therefore, the description "mounted with an interference fit" specifies the structure by indicating the state of completion of the motor, and does not specify the product by the manufacturing method.

In one embodiment, the material of the corrosion resistant ring is an aluminum alloy. For example, the corrosion-resistant ring is an aluminum die-cast product and is subjected to alumite treatment, laser irradiation treatment, or antiseptic coating treatment. Alternatively, the corrosion resistant ring is a cold forged or pressed piece of aluminum.

In another embodiment, the material of the corrosion resistant ring is a ferrous alloy. For example, the corrosion resistant ring is a cold forged or pressed stainless steel product. Alternatively, the corrosion resistant ring is cold forged or pressed and plated. In another embodiment, the material of the corrosion resistant ring is resin.

In the motor of the present invention, a corrosion-resistant ring having corrosion resistance is attached to the inner wall of the opening of the case by interference fit. Therefore, even in an environment where water is splashed heavily, corrosion resistance can be improved against intrusion of water from the adhesive-applied portion.

1 is an overall configuration diagram of an electric power steering device to which a motor according to one embodiment is applied; FIG. 1 is a schematic cross-sectional view of a motor according to one embodiment; FIG. FIG. 3 is an enlarged cross-sectional view of part III of FIG. 2 ; (a) A plan view and (b) a side view of a corrosion-resistant ring.

(one embodiment)
An embodiment of the motor will be described below with reference to the drawings. The motor of this embodiment is a motor that is applied to an electric power steering device for a vehicle and generates a steering assist torque. Further, the motor of the present embodiment is a "machine-electrically integrated type" motor in which an ECU (that is, a control device) is integrally configured on one side of the motor in the axial direction.

First, referring to FIG. 1, a configuration example of an electric power steering device 90 is shown. Steering torque by the driver is transmitted from the steering wheel 91 to the intermediate shaft 93 via the steering shaft 92 , and the rack and pinion mechanism 94 converts the rotary motion into the linear motion of the rack shaft 95 . A pair of wheels 99 are steered at an angle corresponding to the linear motion displacement of the rack shaft 95 .

The motor 80 is attached to a power transmission portion 96 attached to the rack shaft 95 . The exterior of the motor 80 consists of a metal (for example, iron) case 30 attached to the power transmission section 96 and a resin cover 40 located on the opposite side of the power transmission section 96 . The rotation of the output shaft of the motor 80 is transmitted to the rack shaft 95 while being decelerated via gears and pulleys in the power transmission section 96 .

As described in Patent Document 1 (Japanese Patent No. 6160585), in the rack-mounted electric power steering device 90, rainwater bouncing off the road surface, rainwater flowing along the rack shaft 95, condensed water, leaked radiator fluid, The motor 80 is likely to be exposed to the washer fluid or the like. Therefore, an adhesive is applied to the joint between the case 30 and the cover 40 to prevent water from entering the inside from the joint between the case 30 and the cover 40 . Although this provides a certain level of waterproofing effect, in an environment where it is heavily exposed to water, there is a possibility that water will enter the interior from the adhesive-applied portion and cause corrosion. Focusing on this point, the present embodiment aims to provide a motor having improved corrosion resistance against water intrusion from the adhesive-applied portion.

Next, with reference to FIGS. 2 and 3, the configuration of the axial cross section of the motor 80 will be described. The output shaft side of the motor 80 shown on the lower side of FIG. 2 is called the "front side", and the cover 40 side shown on the upper side of FIG. 2 is called the "rear side". The ECU 10 is arranged coaxially with respect to the rotation axis Z on the rear side of the motor 80 .

The electromechanical integrated motor 80 mainly includes a case 30, a stator 50, a rotor 60, and a rear frame 20 that constitute a motor section, an ECU 10 that constitutes a control section, a cover 40, and the like. The motor section constitutes a three-phase brushless motor, and the ECU 10 controls driving of the motor section.

The case 30 is made of metal such as iron, and has a cylindrical portion 31 and a bottom portion 37 . A stator 50 and a rotor 60 are accommodated on the bottom 37 side of the case 30, and the rear frame 20 is fitted on the opening side. At the portion where the rear frame 20 is fitted, the tubular portion 31 of the case 30 has a stepped shape formed by an intermediate inner wall 32 having a relatively small inner diameter and an opening inner wall 33 having a relatively large inner diameter interposed therebetween. is formed in

The stator 50 is configured by laminating a plurality of iron thin plate-like stator cores in the axial direction. The outer wall of the stator 50 is fixed to the inner wall of the cylindrical portion 31 of the case 30 by "interference fit". Hereinafter, interference fitting including fixing of the rear frame 20 and the corrosion resistant ring 70 includes press fitting, shrink fitting, or cooling fitting.

A three-phase winding 52 is wound around the stator 50 . The three-phase windings 52 are connected to the board 15 of the ECU 10 via motor terminals 53 . A rotating magnetic field is formed in the stator 50 by controlling the energization of the three-phase windings 52 by the ECU 10 .

The rotor 60 is configured by laminating a plurality of iron sheet-like rotor cores in the axial direction. The rotor 60 is provided inside the stator 50 and has a shaft 63 fixed at its center. The shaft 63 is rotatably supported by a front bearing 61 held on the bottom 37 of the case 30 and a rear bearing 62 held on the rear frame 20 .

A plurality of permanent magnets 65 are provided on the outer circumference of the rotor 60 . Either the SPM type in which the permanent magnets 65 are provided on the surface of the rotor core or the IPM type in which the permanent magnets 65 are embedded inside the rotor core may be used. Rotor 60 rotates around shaft 63 due to a rotating magnetic field formed in stator 50 by energization of three-phase windings 52 . A joint 67 for transmitting rotation is provided at the front end of the shaft 63 . A sensor magnet 68 for detecting a rotation angle is provided at the rear end of the shaft 63 .

The rear frame 20 is made of an aluminum alloy or the like, and is provided so as to face the rear end surfaces of the stator 50 and the rotor 60 at the opening of the case 30 . A shaft hole 28 through which the shaft 63 is inserted is formed in the center of the body portion 21 . The rear side of the body portion 21 is provided with a screw seat portion used for fixing the substrate 15 with screws, and the front side of the body portion 21 holds a rear bearing 62 . The rear frame 20 supports the substrate 15 and the rear bearing 62 and also functions as a heat sink for receiving heat radiation from elements mounted on the substrate of the ECU 10 .

A flange portion 23 that protrudes radially outward is provided on the outer periphery of the body portion 21 . A front-side end face 25 of the collar portion 23 abuts on a receiving stepped portion 35 of the case 30 . The fixing portion outer wall 22 on the front side of the flange portion 23 is fixed to the intermediate portion inner wall 32 of the case 30 by interference fit. The outer wall 24 of the flange 23 is inserted into the inner wall 33 of the opening of the case 30 with a clearance fit. Thereby, the rear frame 20 is fixed to the case 30 while being axially positioned.

A groove-forming outer wall 27 is provided on the opening side of the case 30 with respect to the flange portion 23 of the rear frame 20 . The groove forming outer wall 27 faces the opening inner wall 33 of the case 30 in the radial direction. Form. The annular groove 34 is filled with, for example, a silicone-based adhesive Ad.

The ECU 10 includes a board 15 fixed to the rear frame 20 and various electronic components mounted on the board 15 . The substrate 15 is fixed to the rear frame 20 with screws. On the surface of the substrate 15 facing the rear frame 20 , a plurality of switching elements, a rotation angle sensor 18 and the like are mounted so as to face a sensor magnet 68 provided at the tip of the shaft 63 . A microcomputer, a capacitor, and the like are mounted on the surface of the substrate 15 opposite to the rear frame 20 . A motor terminal 53 is connected to the substrate 15 through the rear frame 20 . Note that although one substrate 15 is provided in the example of FIG. 2, two or more substrates may be provided in other embodiments.

The cover 40 is made of resin, for example, has a ceiling wall 41 and a peripheral wall 42, and is provided so as to cover the opening of the case. At the end of the peripheral wall 42 on the case 30 side, an eaves portion 43 projecting radially outward and an edge portion 44 to be inserted into the annular groove portion 34 are annularly formed. The inner diameter of the edge portion 44 is set slightly larger than the outer diameter of the grooved outer wall 27 of the rear frame 20 .

When the edge portion 44 is inserted into the annular groove portion 34 filled with the adhesive Ad, the edge portion 44 pushes the adhesive Ad, thereby sealing the gap and bonding the cover 40 to the case 30 . FIG. 3 shows an enlarged view of the joint. The cover 40 protects the electronic components mounted on the substrate 15 from external shocks and prevents dust, water, and the like from entering the ECU 10 . A connector (not shown) to which a power supply cable or a signal cable from the outside is connected may be provided on a part of the cover 40 .

Here, as shown in FIG. 3, there is a possibility that water may enter from the bonding surface between the adhesive Ad and the case 30 and reach the substrate 15 and the motor terminals 53 inside, causing corrosion. As a solution to this problem, a corrosion-resistant ring 70 having corrosion resistance is attached to the inner wall 33 of the opening of the case 30 in the annular groove 34 with an interference fit.

As shown in FIG. 4, the corrosion-resistant ring 70 literally has a ring shape. The corrosion-resistant ring 70 is made of a material having excellent corrosion resistance and adhesiveness, or is surface-treated. Table 1 shows several examples of specific materials and construction methods for the corrosion-resistant ring 70 .

[1A] Material: aluminum alloy for die-casting such as ADC12, method: die-casting and cutting An aluminum die-casting product is cut and finished into a ring shape in which coaxiality and surface roughness are within tolerance. After cutting, alumite treatment, laser irradiation treatment, or antiseptic coating treatment is performed. Compared to applying these surface treatments to the case (made of iron, for example) 30, it is easier to apply the surface treatment to only the corrosion-resistant ring 70, the amount of treatment can be reduced, and it is advantageous in terms of cost.

[1B] Material: Aluminum alloy, Construction method: Cold forging or pressing A ring shape is made from a cold forging or pressing aluminum alloy with excellent corrosion resistance and workability. Machining costs are reduced because cutting and post-processing are not required.

[2] Material: iron alloy, construction method: cold forging or pressing A ring shape is made from cold forging or pressing of iron alloy. For stainless alloys, no post-treatment is required. In the case of general steel other than stainless steel alloys, corrosion-resistant plating is applied.

[3] Material: Resin, Construction method: Injection molding As a characteristic of resin, it does not corrode. Machining and post-processing after molding are not required.

As described above, in the present embodiment, the corrosion-resistant ring 70 is attached to the inner wall 33 of the opening of the case 30 with an interference fit, so that the corrosion resistance of the case inner seal portion against the ingress of water from the adhesive-applied portion is improved. can be made In addition, since the creepage distance (see FIG. 3) of the bonding portion can be shortened by increasing the corrosion resistance, the motor 80 can be miniaturized.

Furthermore, since the amount of the adhesive Ad with which the annular groove 34 is filled is reduced, the tact time of the adhesive application process can be shortened. In addition, even if a material with good adhesion cannot be selected for the case 30, corrosion resistance and adhesion can be ensured by using the corrosion-resistant ring 70 as a common component.

Regarding the assembling property of the corrosion-resistant ring 70 , axial positioning can be performed by abutting the end surface of the corrosion-resistant ring 70 against the rear-side end surface 26 of the collar portion 23 of the rear frame 20 . The interference fit may be press fit or shrink fit. In the case of shrink fitting, it is possible to fit without depending on the strength property based on the material of the corrosion resistant ring 70 .

(Other embodiments)
(a) The present invention is not limited to the electromechanical integrated motor in which the ECU 10 is integrated with the motor 80 (that is, the "driving device" in Patent Document 1), but the electromechanical separate type in which the ECU 10 is connected to a separate control device with a harness. It may be applied to motors. In that case, the rear frame 20 may simply be a member that holds the rear bearing 62 in the opening of the case 30 without functioning as a heat sink for releasing heat generated by the elements on the substrate.

(b) The mating portion between the rear frame 20 and the case 30 is not limited to the configuration of the flange portion 23, the receiving step portion 35, etc. shown in FIGS. good too. The minimum requirements are that the outer wall of the rear frame 20 is fixed to the inner wall of the cylindrical portion 31 of the case 30 by interference fit, and that an annular groove portion 34 is formed between the rear frame 20 and the case 30. .

(c) The cover 40 is not limited to resin. Further, the cover 40 is not limited to being formed as a single part, and for example, a cover main body and a connector to which a cable is connected may be formed separately and joined with an adhesive or the like. In that case, the edge portion 44 may be formed at the end portion of the "connector forming part of the cover" on the case 30 side.

(c) The case 30 is not limited to the configuration in which the bottom portion 37 is formed integrally with the tubular portion 31 , and a front frame formed separately from the tubular portion 31 may be fixed to the tubular portion 31 .

(d) The motor of the present invention is not limited to a permanent magnet type polyphase AC motor, and may be a DC motor, an induction motor, or the like. Moreover, it may function as a generator.

(e) The motor of the present invention may be applied not only to a rack-mounted electric power steering apparatus but also to a column-mounted electric power steering apparatus. Further, the present invention may be applied to in-vehicle devices other than the electric power steering device, and various devices other than the devices mounted in the vehicle.

As described above, the present invention is not limited to such an embodiment, and can be embodied in various forms without departing from the spirit of the present invention.

20... rear frame,
22: Fixed portion outer wall, 27: Groove-forming outer wall,
30 Case,
32... Intermediate portion inner wall, 33... Opening portion inner wall, 34... Annular groove portion,
40... Cover, 44... Edge,
50 Stator,
60 Rotor,
70 Corrosion-resistant ring,
80 motor.

Claims (10)

a metal case (30) having a cylindrical portion (31) and a bottom portion (37), being open on the opposite side of the bottom portion and containing a stator (50) and a rotor (60);
A fixing portion outer wall (22) fixed to an intermediate inner wall (32) of the cylindrical portion of the case by interference fit, and an opening inner wall (33) of the case on the opening side of the case from the fixing portion outer wall. a rear frame (20) having a groove-forming outer wall (27) forming an annular groove (34) between
a cover (40) provided to cover the opening of the case and joined to the case by inserting an edge (44) into the annular groove filled with an adhesive (Ad);
a corrosion-resistant ring (70) that is corrosion-resistant and is attached to the inner wall of the opening of the case in the annular groove with an interference fit;
motor. 2. The motor according to claim 1, wherein the material of said corrosion-resistant ring is an aluminum alloy. 2. A motor according to claim 1, wherein the material of said corrosion-resistant ring is an iron alloy. 2. The motor according to claim 1, wherein the corrosion-resistant ring is made of resin. 3. The motor according to claim 2, wherein said corrosion-resistant ring is an aluminum die-cast product and is subjected to alumite treatment. 3. The motor according to claim 2, wherein said corrosion-resistant ring is an aluminum die-cast product and is subjected to laser irradiation treatment. 3. The motor according to claim 2, wherein said corrosion-resistant ring is an aluminum die-cast product and is coated with an antiseptic agent. 3. The motor according to claim 2, wherein the corrosion resistant ring is a cold forged or pressed aluminum alloy. 4. The motor according to claim 3, wherein the corrosion resistant ring is a cold forged or pressed stainless steel product. 4. The motor according to claim 3, wherein the corrosion resistant ring is a cold forged product or a pressed product and is plated.

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