JP7379786B2 - Brushed DC motor and its manufacturing method - Google Patents

Description

The present invention relates to a brushed DC motor and a method for manufacturing the same, and more particularly to a brushed DC motor suitable for a small motor for use in a vehicle, and a method for manufacturing the same.

Brushed DC motors, such as small DC motors installed in vehicles, are brushes in which multiple permanent magnets are arranged on the inner circumferential surface of a cylindrical motor case with a bottom, and a rotor is rotatably installed inside the permanent magnets. There is a DC motor with a

Patent Document 1 discloses a brushed DC motor including a motor case having a cylindrical portion, two pairs of permanent magnets arranged opposite to each other on the inner circumferential surface of the cylindrical portion, and rotatably supported inside these permanent magnets. A motor is disclosed in which a cylindrical portion is provided with at least a pair of radially opposed flat portions, and permanent magnets are disposed at positions away from these flat portions. The brush holder unit of this DC motor is provided with a pair of flat walls flush with a pair of flat parts provided on the motor case. By making the width of the pair of flat portions of the motor case smaller than the diameter of the cylindrical portion, there is an advantage that the motor can be made smaller than when the entire cylindrical portion is formed into a cylindrical shape.
Patent Document 2 also discloses a DC motor with a brush, which includes a brush holder having a pair of flat parts corresponding to the flat plate part of a motor case.

A brushed DC motor uses brushes to perform commutation with a commutator, and sparks generated when the commutator and brushes come into contact during commutation generate electrical noise. This electrical noise may cause other electrical components such as various controllers installed in the vehicle to malfunction. Therefore, with regard to in-vehicle DC motors, in order to eliminate adverse effects on other electrical components, regulations on the permissible value of noise generated by brushes are internationally defined as EMC (electric magnetic compatibility) standards.

In the electric motor described in Patent Document 1, a circuit including a pair of capacitors and a pair of choke coils is provided in the brush holder unit as means for suppressing electrical noise. A midpoint terminal grounded to ground is connected between the pair of capacitors.

Further, the brushed electric motor described in Patent Document 2 also includes a circuit for suppressing electrical noise including a pair of capacitors and a pair of choke coils in the brush holder unit. A pair of capacitors and a pair of ground terminals are attached to a pair of flat sides of the brush holder.

WO2013/175624 A1 Japanese Patent Application Publication No. 2010-57298

In conventional DC motors, a ground terminal is used to electrically connect a ground terminal (earth terminal) provided on a brush holder unit (hereinafter referred to as an end cap assembly in the present invention) to a metal motor case, etc. A method in which the end of the ground wire connected to the motor case is brought into elastic contact with the motor case, a method in which the end of the wire is held between the end cap assembly and the motor case and contacted in a restrained state, and a method in which the end of the wire is brought into contact with the end cap assembly and the motor case in a restrained state. A known method is to mechanically fix the part to a groove provided in a motor case or the like by soldering or the like. A method in which the end portions of the wiring are brought into elastic contact or a method in which the wires are clamped have a simpler manufacturing process than a method in which they are fixed, and therefore have the advantage that the motor can be manufactured at a lower cost.
On the other hand, with the method of elastically contacting or clamping the end of the grounding wire, depending on how the brush holder is installed, the electrical connection between the ground terminal and the motor case, etc. may be incomplete. . Furthermore, if vibrations from a vehicle drive source such as the engine are applied for a long period of time, the tip of the grounding wire may become deformed, making the electrical connection with the motor case unstable. If such an incomplete contact state occurs, the means for suppressing electrical noise will not function properly.

Patent Document 1 does not include any detailed description regarding the electrical connection between the ground terminal and the motor case.

In the invention described in Patent Document 2, the ground terminal is configured as a branch piece having a plurality of branched tips, and has a structure in which the tips are brought into elastic contact with the motor case. According to the invention disclosed in Patent Document 2, the tip of the ground terminal is branched into multiple parts, so even if the ground terminal deviates from its normal posture due to improper installation, at least a portion of the tip of the ground terminal is branched. It is possible to ensure a contact state between the earth terminal and the motor case, and it is possible to improve the reliability of the electrical connection between the ground terminal and the motor case.

However, in the invention described in Patent Document 2, the capacitor and the mounting groove for the ground terminal are arranged side by side along both flat side surfaces of the brush holder. In such a structure in which the capacitor and the mounting groove are arranged side by side along the outer circumferential direction of the brush holder, the size of the mounting groove must be reduced. Therefore, the size of the ground terminal mounted in the mounting groove, and by extension, the tip portion of the ground terminal branched into a plurality of parts, becomes small. If this is assumed to be adopted as a motor for the drive source of a valve device mounted on a vehicle engine, a large external force such as vibration from the engine will be applied to the tip of the ground terminal for a long period of time. As a result, the small-sized tip portion may be deformed, and sufficient contact between the ground terminal and the motor case may not be ensured, and the function of suppressing electrical noise may not be maintained.

One of the problems of the present invention is to create a system in which the tip of the ground terminal is brought into elastic contact with the motor case, and which also has sufficient mechanical strength to prevent it from easily deforming even when external forces such as vibrations are applied. An object of the present invention is to provide a brushed DC motor equipped with a highly reliable ground terminal that can maintain electrical connection even during long-term use.
Another object of the present invention is to provide a method for manufacturing a brushed DC motor that has a highly reliable ground terminal that has sufficient mechanical strength and can withstand long-term use.

According to one aspect of the invention, a brushed DC motor includes:
a cylindrical motor case with one end open; a pair of permanent magnets held in the motor case; a rotor rotatably supported within the motor case via a rotating shaft; and the one end of the motor case. a commutator that rotates integrally with the rotating shaft within the motor case; a brush that contacts the outer peripheral surface of the commutator; and a noise prevention circuit that suppresses noise.
The motor case has a curved surface part along the outer periphery of the permanent magnet and a flat part between the permanent magnets, and the noise prevention circuit is a DC motor including at least one pair of capacitors and one earth terminal. In,
The end cap assembly has a curved outer circumferential portion corresponding to the curved portion of the motor case, and a planar outer circumferential portion corresponding to the flat portion of the motor case,
One of the planar peripheral portions has a flat wall portion,
a pair of capacitor mounting holes for accommodating the pair of capacitors on the inside of the flat wall;
The earth terminal has a base portion and a plurality of branch pieces formed at one end of the base portion,
In the ground terminal, the base portion is in contact with the inner surface of the flat wall portion, and the branch piece is sandwiched between the outer surface of the flat wall portion and the inner surface of the motor case, and is elastically attached to the motor case. held by the flat wall portion in contact with each other;
The at least one pair of capacitors is configured to be grounded to the motor case via the base portion and the branch piece of the earth terminal.

According to another aspect of the present invention, a grounding groove parallel to the inner surface of the flat wall is provided between the lower part of the inner surface of the flat wall and the pair of capacitor mounting holes. It is characterized by being provided with.

The ground terminal of the present invention can be increased in size because it is held on the flat wall of the end cap assembly, which is flat and has a large area. Since the mechanical strength is high, it is possible to provide a ground terminal that can maintain electrical connection for a long period of time, in other words, can maintain the function of suppressing electrical noise for a long period of time. For example, it is possible to provide a highly reliable ground terminal that can withstand long-term use even when used in an environment subject to large vibrations, such as in a vehicle engine.

FIG. 1 is an exploded perspective view of a brushed DC motor according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view of the DC motor shown in FIG. 1 in the Z direction. FIG. 2 is a vertical cross-sectional view of the DC motor shown in FIG. 1 in the Y direction. FIG. 3 is a perspective view showing the inner surface of the end cap assembly of the DC motor according to the first embodiment. FIG. 3 is a diagram showing the structure and manufacturing method of a ground terminal incorporated into the end cap assembly. FIG. 3 is a side perspective view of the end cap assembly. FIG. 3 is an electrical circuit diagram of the DC motor. It is a flowchart which shows the manufacturing method of the said DC motor. FIG. 6 is a developed view showing the process of connecting the ground terminal, the capacitor, and the power terminal. FIG. 6 is a cross-sectional view of a main part showing an initial stage of a step of attaching the ground terminal to the end cap body. FIG. 7 is a sectional view of a main part showing the final stage of the process of attaching the earth terminal to the end cap body. FIG. 3 is a perspective view showing a manufacturing process of the end cap assembly.

Hereinafter, a brushed DC motor according to an embodiment of the present invention will be described.
First, the overall configuration of the DC motor of this embodiment will be explained with reference to FIGS. 1 to 3.
FIG. 1 is an exploded perspective view of a brushed DC motor according to this embodiment. 2 is a cross-sectional view of the DC motor shown in FIG. 1, and FIG. 3 is a vertical cross-sectional view of the DC motor shown in FIG.
The brushed DC motor 100 includes a bottomed cylindrical motor case 110 made of a conductive material, for example, a magnetic material such as iron, and a C-shaped motor case 110 fixed in the motor case 110. The permanent magnets 112, 112 of the poles, the permanent magnet retainer 113, the rotor 120 rotatably supported within the motor case 110 via the rotating shaft 121, and the synthetic resin fixed to the opening 1103 of the motor case 110. end cap assembly 130.

The outer peripheral portion of the motor case 110 has a pair of curved portions 1101 along the outer peripheries of the pair of permanent magnets 112, 112, and a pair of flat portions 1102 between these permanent magnets. The end cap assembly 130 includes a pair of curved outer peripheral parts 131 corresponding to the curved part 1101 of the motor case, a pair of flat outer peripheral parts 132 corresponding to the flat part 1102 of the motor case, and a rotating shaft corresponding to the rotating shaft 121. It has a hole 133.
A pair of flat parts 1102 of the motor case 110 extend parallel to the axis OO of the rotating shaft 121. The rotating shaft 121 is rotatably supported by a sleeve bearing 114 provided on the motor case 110 and a ball bearing 115 provided on the shield cap 144.

The rotor 120 of the DC motor has a coil 122 and a commutator 124. The end cap assembly 130 houses a pair of carbon brushes 126 that are in sliding contact with the commutator 124 to supply current to the coil 122. A pair of brushes 126 are connected to a pair of power terminals 140 held on end cap assembly 130. Further, a pair of capacitors 150 and one earth terminal 160, which constitute an electrical noise prevention circuit and are connected to the brush 126 and the power terminal 140, are held in the end cap assembly 130.
A pair of planar outer circumferential portions 132 of the end cap assembly 130 are provided with a pair of flat wall portions 134 (A, B) extending in the axis OO direction, and further, one of the flat wall portions 134 ( A slope 1381 for grounding and a groove 1382 for grounding are provided on the inside of A). The earth terminal 160 is bent into a U-shape and is held by the one flat wall portion 134, and the inner part of the U-shape is in contact with the earth attachment slope 1381 and the earth attachment groove 1382. In addition, when the extension part 139 of the end cap assembly is inserted and fixed into the opening 1103 of the motor case 110, the U-shaped outer surface portion of the ground terminal 160 is connected to the inner surface of the opening 1103 of the motor case 110 and a flat plate. A ground terminal 160 is sandwiched between the shaped wall portion 134A and electrically connected to the motor case 110.
A gear 142 that constitutes a part of a reduction mechanism on the output side of the DC motor is fixed to one end of the rotating shaft 121.

Next, the configurations of the end cap assembly 130 and the ground terminal 160 of this embodiment will be described with reference to FIGS. 4 to 6. FIG. 4 is a perspective view of the inner surface of the end cap assembly, FIG. 5 is a diagram showing the structure and manufacturing method of the earth terminal, and FIG. 6 is a perspective view of the side of the end cap assembly.
Reference numeral 138 designates an end cap main body, and a pair of planar outer peripheral portions 132 constituting the outer peripheral surface thereof are each provided with a flat wall portion 134 (A, B). , B) each have an outer surface 135 of the flat wall and an inner surface 136 of the flat wall, which extend parallel to the axis OO direction of the rotating shaft 121.
The end cap body 138 further includes a pair of brushes 126 (A, B), a pair of capacitor mounting holes 137 (A, B), a pair of brush springs 127 (A, B), and a pair of pigtails 128 (A, B). ), and a pair of power supply terminals 140 (A, B) are provided.
On the end cap body 138 and on the radially inner side of one flat wall 134A, that is, between the inner surface 136 of the flat wall 134A and the rotation shaft hole 133, the inner surface 136 of the flat wall 134A is A pair of capacitor mounting holes 137 are provided along the same. A pair of capacitors 150 (A, B) are fixed in these capacitor mounting holes 137, and a tapered ground mounting slope 1381 extending in the axis OO direction is provided between them. There is. Furthermore, a grounding groove 1382 parallel to the inner surface of the flat wall 134A is provided between the lower part of the inner surface 136 of the flat wall 134A and the pair of capacitor mounting holes 137 on the radially inner side thereof. (See Figures 10 and 11).
A ground terminal 160 is further held on one flat wall portion 134A, and a pair of capacitors 150 and a pair of power supply terminals 140 are connected to this ground terminal 160.

As the material of the earth terminal, a plate material having a predetermined shape, such as a brass plate, which has excellent conductivity, elasticity, and rigidity is used. The earth terminal 160 is formed by cutting and bending this brass plate. The thickness of the brass plate is approximately 0.2 mm to 0.5 mm.
As shown in FIG. 5A, the ground terminal 160 includes a flat rectangular ground terminal base portion 1604 and a pair of branch pieces extending from one end of the base portion 1604, that is, a first rectangular ground terminal. It has a branch piece 1601, a second ground terminal branch piece 1602, and an earth terminal holding claw 1603 formed between these branch pieces.
As shown in FIG. 5B, the earth terminal 160 is formed by bending a pair of branch pieces (1601, 1602) and a holding claw 1603 into a U-shape with respect to a base portion 1604.
Furthermore, a reinforcing rib 1605 and an attachment/holding protrusion 1606 are provided at the center of the base portion 1604 of the earth terminal 160. The reinforcing rib 1605 has a rectangular flat top. This reinforcing rib is for increasing the section modulus of the base portion, and its shape can be set arbitrarily. The attachment and holding protrusion 1606 functions to press the base portion 1604 against the inner surface 136 of the flat wall portion 134A, and the height of its apex is greater than the height of the reinforcing rib 1605. Further, the height of the apex of the attachment holding protrusion 1606, which includes the thickness of the earth terminal 160, is larger than the width of the earth attachment groove 1382. Note that a plurality of attachment and holding protrusions 1606 may be provided symmetrically at the lower part of the base portion 1604.
As shown in FIGS. 4 and 6, this earth terminal 160 has a base portion 1604 located on the inner surface 136 side of the flat wall portion 134A, and a pair of branch pieces 1601, 1602 and one holding claw 1603 that have a flat plate shape. It is held by the flat wall 134A so as to be located on the outer surface 135 side of the wall 134A.

Since the ground terminal 160 of this embodiment is held using the flat surfaces on both sides of the flat wall portion 134A of the end cap assembly 130, which has a flat and wide area, its size can be increased. Therefore, it is possible to obtain the earth terminal 160 which has excellent conductivity, elasticity and rigidity, and has high mechanical strength as a whole.
In FIG. 5A, when the width of the base portion 1604 is W0, the length is L1, and the length of the pair of ground terminal branch pieces 1601 and 1602 is L2, these have the following relationship.
The width W0 of the base portion 1604 is longer than the distance between the centers of the pair of capacitor mounting holes 137, 137, and shorter than the length of the flat wall portion 134A in the axis OO direction. The length L1 of the base portion 1604 is longer than the width W0. The length L2 of the ground terminal branch pieces 1601 and 1602 is longer than the width W0, and the length of the base portion 1604 is shorter than L1.
Further, assuming that the width of the ground terminal branch pieces 1601 and 1602 is W1, and the width of the holding claw 1603 is W2, an example of the specific size of the ground terminal 160 is as follows.
The thickness of the brass plate is 0.3 mm, the width W0 of the base portion is 7.3 mm, and the length L1 is 10.2 mm. Furthermore, the width W1 of the ground terminal branch pieces 1601 and 1602 is 1.2 mm, and the width W2 of the holding claw 1603 is 1.6 mm.

FIG. 7 is an electrical circuit diagram of the DC motor 100 according to this embodiment. A pair of capacitors 150 (A, B) are connected between the pair of brushes 126 (A, B) of the DC motor 100 and the power terminals 170 (A, B) via the power terminals 140 (A, B). These capacitors are electrically connected via an earth terminal 160 to the inner surface of the motor case forming a ground. That is, the pair of capacitors 150 (A, B) are configured to be grounded to the motor case via the base portion 1604 of the earth terminal 160 and the pair of branch pieces (1601, 1602).

According to the DC motor according to this embodiment, the tip of the ground terminal 160 is branched into a pair of branch pieces (1601, 1602). Therefore, even if the ground terminal deviates from its normal position relative to the motor case due to the installation condition of the ground terminal, the flexible elastic deformation of the branch pieces will cause at least one branch piece to come into contact with the inner surface of the motor case. , the electrical connection can be maintained.
Moreover, since each branch piece is large in size, it has sufficient mechanical strength that it is not easily deformed even when external force such as vibration is applied. Therefore, it is possible to provide a brushed DC motor equipped with a highly reliable ground terminal that can withstand long-term use.

Next, with reference to the flowchart of FIG. 8 and FIGS. 9 to 12, a method of manufacturing a DC motor, in particular a method of manufacturing an end cap assembly, according to this embodiment will be described.
FIG. 9 is a diagram showing the process of connecting the ground terminal 160, the capacitors 150 (A, B), and the power supply terminal 140.
First, a pair of legs 1501 and 1502 of a pair of capacitors 150 (A, B) are formed and cut, respectively (S801).
Next, one leg 1501 of the pair of capacitors 150 (A, B) is each fixed to the base portion 1604 of the earth terminal 160 by spot welding (S802).
Next, epoxy resin is applied to the capacitor mounting holes 137 (A, B) of the end cap body 138 (S803).
Next, the pair of capacitors 150 (A, B) are respectively inserted into the pair of capacitor mounting holes 137 (A, B), and the base portion 1604 of the ground terminal 160 is attached to the inner surface 136 side of the flat wall portion 134A. , into the grounding groove 1382 (S804).
Next, the earth terminal 160 is held on the flat wall portion 134A of the end cap using the holding claw 1603 and the pair of branch pieces (1601, 1602) (S805). In this way, the ground terminal 160 is held on the flat wall portion 134A of the end cap body 138.

FIG. 10 is a diagram showing the first stage of the process of attaching the ground terminal 160 to the end cap body 138. The tapered ground mounting slope 1381 has the function of facilitating insertion of the base portion 1604 of the ground terminal 160 into the ground mounting groove 1382. That is, when inserting the base portion 1604 of the earth terminal into the earth installation groove 1382, the base portion 1604 does not go toward the capacitor installation hole 137, and can be stably inserted into the earth installation groove 1382. It is. When inserted into the grounding groove 1382, the mounting and holding protrusion 1606 has the function of pressing the base portion 1604 against the inner surface 136 of the plate-like wall portion and holding the grounding terminal 160 in place. The height of the reinforcing rib 1605 is set so that it does not come into contact with the ground mounting slope 1381.

FIG. 11 is a diagram showing the final stage in which the ground terminal 160 is attached to the end cap body 138. In the earth terminal 160, the base portion 1604 is completely inserted into the earth attachment groove 1382 and pressed against the inner surface 136 of the flat wall portion 134A, while the base portions of the holding claw 1603 and the branch pieces 1601, 1602 are It is held by the flat wall 134A by elastically contacting the outer surface 135 of the flat wall 134A.

Returning to FIG. 8, next, the end cap body 138 is placed in an electric furnace to harden the epoxy resin in the capacitor mounting hole 137 (S806).
Next, the ends of the pigtails 128 (A, B) of the pair of brushes 126 (A, B) are placed on the power terminal extensions 1402 (see FIG. 9) of the pair of power terminals 140 (A, B), respectively. It is fixed by welding (S807).
Furthermore, a pair of power supply terminals 140 (A, B) are inserted into the end cap body 138 and fixed respectively (S808).

Then, the other legs 1502 of the pair of capacitors 150 (A, B) are each fixed by spot welding to the power terminal heads 1401 at each end of the pair of power terminals 140 (A, B) (S809).
FIG. 9 shows how the other leg 1502 of the pair of capacitors 150 (A, B) is fixed. Further, hatched portions in FIG. 12 are perspective views showing portions related to the manufacturing steps (S807) to (S809) of the end cap assembly.

Returning to FIG. 8, next, a pair of carbon brushes 126 (A, B) are inserted into the pair of holder parts of the end cap body 138 (S810), and a pair of brush springs 127 ( A and B) are attached (S811) to complete the end cap assembly 130.
Then, by attaching this end cap assembly 130 to the rotating shaft 121 of the rotor 120 (S812) and incorporating the rotor 120 and the end cap assembly 130 into the motor case 110, the pair of branch pieces 1601 and 1602 of the earth terminal 160 are , are sandwiched between the outer surface 135 of the flat wall portion 134A and the inner surface of the motor case 110, and the pair of branch pieces 1601 and 1602 come into elastic contact with the inner surface of the motor case 110. Thereby, ground terminal 160 and motor case 110 are electrically connected (S813).

The ground terminal 160 of this embodiment is held using the flat surfaces on both sides of the flat wall portion 134A of the end cap assembly 130, which has a flat and wide area. The size of 1602 can be increased. Therefore, it is possible to obtain the earth terminal 160 which has excellent conductivity, elasticity and rigidity, and has high mechanical strength as a whole for a long period of time.
According to this embodiment, the ground terminal is in elastic contact with the motor case, and has a structure that has sufficient mechanical strength to prevent it from easily deforming even when external forces such as vibrations are applied. ing. Therefore, it is possible to provide a brushed DC motor equipped with a highly reliable ground terminal that can maintain electrical connection even after long-term use.
In addition, since the ground terminal is thin, even if the ground terminal is provided on the flat wall of the end cap, the advantage is that the motor can be made smaller by making the width of the flat part of the motor case smaller than the diameter of the cylindrical part. not damaged.

Variant

In the present invention, the ground terminal 160 includes a base part 1604 and a plurality of branch pieces (1601, 1602) extending from one end thereof, and the ground terminal 160 is connected to both sides of the flat wall part 134A of the end cap assembly 130. One of the features is that it is configured to be held using (135, 136). The configuration of the earth terminal can be arbitrarily changed within the range provided with this feature.
For example, the ground terminal 160 may be provided with two pairs of branch pieces. In this case, one holding claw may be provided at the center, or one holding claw may be provided between each branch piece.
Conversely, the holding claws may be omitted by providing the two pairs of branch pieces with the function of holding claws.
Alternatively, the length of one holding claw between a pair of branch pieces may be made slightly longer so that this holding claw has the function of a branch piece, that is, a function as a ground terminal.
The configurations such as the number and shape of the branch pieces and retaining claws shown in these modified examples have the effect of the present invention in that they can provide a ground terminal that has high mechanical strength and can maintain the function of suppressing electrical noise for a long period of time.・You may set it as appropriate within a range that does not impair the effect.

In the first embodiment, an example was shown in which a circuit consisting of a pair of capacitors was mounted on the end cap assembly as a means for suppressing electrical noise, but the present invention is not limited to this. The earth terminal 160 of the present invention can be employed even when the end cap body 138 is equipped with a circuit including a pair of choke coils in addition to a pair of capacitors as a means for suppressing electrical noise. That is, even if a circuit compatible with common mode or normal mode is mounted on the end cap assembly, the earth terminal 160 of the present invention can be employed.

Although the first embodiment shows an example of a two-pole brushed DC motor, the present invention is not limited to this. A 4-pole brushed DC motor also has two pairs of curved surfaces along the outer periphery of two pairs of permanent magnets, and two pairs of flat surfaces between each permanent magnet. If so, the ground terminal 160 similar to that in the first embodiment can be installed by forming the flat wall portion 134A using any one of the flat portions of the corresponding end caps.
In addition, in a small brushed DC motor with a larger number of poles than a 4-pole motor, the length of the flat part of the end cap becomes shorter, so the size of the ground terminal 160 becomes smaller, making it difficult to ensure its mechanical strength. Become. Therefore, it is not practical to provide such a motor with the earth terminal of the present invention.

The brushed DC motor of the present invention can be employed as a drive source for a motor-driven valve device, such as an EGR valve or an electronic throttle device for an automobile engine, for example. That is, it can be used as a DC motor for driving a valve device mounted on a car engine. In this case, external force due to vibration from the engine always acts, but according to the present invention, by utilizing the flat wall part of the end cap, it has sufficient mechanical strength that does not easily deform, and it can be used for a long period of time. It is possible to provide a highly reliable ground terminal that can maintain electrical connection even when used with Thereby, it is possible to provide a motor-driven valve device that reduces electrical noise and can withstand long-term use.

100 DC motor 110 Motor case 1101 Curved outer peripheral part of motor case 1102 Planar part of motor case 1103 Opening part of motor case 112 Permanent magnet 113 Permanent magnet holder 114 Sleeve bearing 115 Ball bearing 120 Rotor 121 Rotating shaft 122 Coil 124 Commutator 126 Brush 127 Brush spring 128 Pigtail 130 End cap assembly 131 Curved outer periphery of end cap 132 Planar outer periphery of end cap 133 Rotating shaft hole 134 Flat wall 135 Outer surface of flat wall 136 Inner surface of flat wall 137 Capacitor mounting Hole 138 End cap body 1381 Ground mounting slope 1382 Ground mounting groove 139 Extension 140 Power terminal 1401 Power terminal head 1402 Power terminal extension 142 Gear 144 Shield cap 150 Capacitor 1501 One leg of the capacitor 1502 The other leg of the capacitor 160 Earth terminal 1601 Earth terminal first branch piece 1602 Earth terminal second branch piece 1603 Earth terminal holding claw 1604 Earth terminal base portion 1605 Reinforcement rib 1606 Mounting and holding protrusion 170 Power terminal

Claims (6)

a cylindrical motor case with one end open; a pair of permanent magnets held in the motor case; a rotor rotatably supported within the motor case via a rotating shaft; and the one end of the motor case. a commutator that rotates integrally with the rotating shaft within the motor case; a brush that contacts the outer peripheral surface of the commutator; and a noise prevention circuit that suppresses noise.
The motor case has a curved surface part along the outer periphery of the permanent magnet and a flat part between the permanent magnets, and the noise prevention circuit is a DC motor including at least one pair of capacitors and one earth terminal. In,
The end cap assembly has a curved outer circumferential portion corresponding to the curved portion of the motor case, and a planar outer circumferential portion corresponding to the flat portion of the motor case,
One of the planar outer peripheral portions has a flat wall portion extending in the direction of the axis OO of the rotating shaft ,
a pair of capacitor mounting holes for accommodating the pair of capacitors on the inside of the flat wall;
The earth terminal has a flat rectangular base portion and a plurality of branch pieces extending from one end of the base portion, and the branch pieces are formed by being bent into a U-shape with respect to the base portion. and
The width and length of the rectangular base portion of the ground terminal are longer than the distance between the centers of the pair of capacitor mounting holes,
In the ground terminal, the rectangular base portion is in contact with the inner surface of the flat wall portion, and the branch piece is sandwiched between the outer surface of the flat wall portion and the inner surface of the motor case, and is attached to the motor case. held by the flat wall portion in elastic contact;
A brushed DC motor characterized in that the at least one pair of capacitors is configured to be grounded to the motor case via the base portion and the branch piece of the earth terminal. The DC motor according to claim 1,
A grounding groove parallel to the inner surface of the flat wall is provided between the lower part of the inner surface of the flat wall and the pair of capacitor mounting holes. Brushed DC motor. The DC motor according to claim 2,
The base portion of the earth terminal is provided with an attachment and holding protrusion,
The brushed DC motor is characterized in that the height of the apex of the attachment holding protrusion, including the thickness of the earth terminal, is greater than the width of the earth attachment groove. The DC motor according to claim 1,
A brushed DC motor characterized in that it has an earth terminal holding claw formed between the branch pieces, extending from one end of the base part, and held on the outer surface of the flat wall part. A brushed DC motor according to claim 1, wherein the DC motor is a drive source for an on-vehicle motor-driven valve device. A method for manufacturing a DC motor according to claim 2 , comprising:
fixing one leg of each capacitor to the base portion of the ground terminal;
Each of the capacitors is inserted into the capacitor mounting hole, and the base portion of the ground terminal is inserted into the ground mounting groove of the flat wall portion, and the ground terminal is inserted into the flat plate of the end cap assembly. Hold it against the shaped wall,
Fixing each of the capacitors to the capacitor mounting holes with epoxy resin,
fixing the other leg of each capacitor to a power terminal;
A method of manufacturing a brushed DC motor, comprising: assembling the rotor and the end cap assembly in the motor case, and bringing the plurality of branch pieces of the ground terminal into contact with the motor case.

Images