JP2007006633A - Motor and fuel pump using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor with improved rectifying property between a brush and a commutator and a fuel pump using this motor. <P>SOLUTION: In the motor, four permanent magnets 32 are installed at equal intervals on the circumference, and they alternately form different magnetic poles in the direction of rotation. Six coils 62, 63 rotatably disposed on the inner circumferential side of the permanent magnets 32 are respectively concentratedly wound, and they are annularly delta connected as a whole. The commutator includes 12 segments 72. The number of 12 is equivalent to the maximum number s expressed as s=n×p/2, where p is the number of the permanent magnets 32 and n is the number of the coils 62 of the armature. The segments 72 installed on the opposite sides in the radial direction are electrically connected with each other. In conjunction with rotation, brushes 120, 122 made of carbon and each segment 72 are repeatedly brought into contact and broken away, and this varies the segment voltage applied to the segments 72. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electric motor and a fuel pump using the same.

A drive current supplied to the armature by installing a commutator that is electrically connected to a plurality of coils wound around the armature and contacting each segment of the brush and commutator as the armature rotates An electric motor that rectifies the current is known.
In such an electric motor, when the concentrated winding which winds a coil | winding for every coil is employ | adopted, since a coil | winding can be wound with high density for every coil, the number of turns of a coil can be increased. As a result, the torque generated with respect to the supplied power increases, so that motor efficiency increases. If the motor efficiency is the same, the electric motor can be downsized.
However, when the number of turns of the coil increases due to concentrated winding, the inductance of the coil increases. As a result, the electromagnetic energy accumulated in the coil increases, and the rectification between the commutator and the brush becomes disadvantageous.

  The present invention has been made to solve the above problems, and it is an object of the present invention to provide an electric motor and a fuel pump using the same that improve commutation between a brush and a commutator.

  Permanent magnets that alternately form different magnetic poles are installed on the circumference, an armature is installed rotatably on the inner circumference side of the permanent magnet, and the commutator divided into a plurality of segments in the rotational direction contacts the brush In the electric motor that rectifies the current supplied to the armature coil by, where s is the number of commutator segments, p is the number of permanent magnets, and n is the number of armature coils, the number of commutator segments s is The electric motor can be configured so that s = n × p / 2 at the maximum.

  According to the first to sixth aspects of the present invention, the number of commutator segments s is maximized as s = n × p / 2. As the number of commutator segments increases, the amount of change in the voltage of each segment that increases or decreases by contacting the brush while rotating decreases. That is, the rectifying load per operation when the brush repeatedly contacts and separates from each segment of the commutator is reduced. Thereby, even if the coil is concentrated and the inductance is increased, the rectification between the commutator and the brush can be improved. Further, since the plurality of coils are delta-connected in a ring shape, the electromagnetic energy accumulated in the coils can flow to the adjacent coils when the brush leaves one segment having the commutator. Therefore, the commutation between the commutator and the brush can be improved. As a result, the life of the brush and commutator can be extended.

  Further, in the invention according to claims 1 to 6, since the rotation direction width of the brush is equal to or less than the rotation direction width of the segment of the commutator at the contact portion between the brush and the commutator, the brush has three continuous portions in the rotation direction. Do not touch at the same time as the segment. That is, by using at most two segments that are in contact with the brush at the same time, the number of coils to which a voltage can be applied between the brushes is prevented from decreasing. This prevents the amount of change in the segment voltage of the commutator from increasing. Therefore, the commutation between the commutator and the brush can be improved.

  Here, in the electric motor, it is desirable that the number n of coils that is the number of magnetic poles of the armature is close to the number p of permanent magnets that is the number of magnetic poles on the stator side. However, if the number n of coils is equal to the number p of permanent magnets, the armature may not rotate depending on the rotational position of the armature at the start. Further, when the number n of coils is smaller than the number p of permanent magnets, torque fluctuation when the armature rotates increases.

Therefore, in the second aspect of the invention, by setting n = p + 2, torque fluctuation when the armature rotates is reduced while the number n of coils and the number p of permanent magnets are brought close to each other.
In the invention of claim 3, if the number of permanent magnets is p, the angular interval between the + side brush and the − side brush is set to 360 ° / p. With this configuration, the angular interval between the different magnetic poles of the permanent magnet is matched with the electrical polarity switching angle by the brush.

In the invention according to claim 4, a plurality of connection terminals are configured such that the plurality of connection terminals are shifted in the axial direction of the armature, and the connection terminals of each connection terminal group are installed on the opposite side in the radial direction of the commutator. Segments (hereinafter, “segments installed on the opposite side in the radial direction” are referred to as opposing segments) are electrically connected to each other.
As a result, since it is not necessary to electrically connect all the opposed segments with the connection terminals installed on the same surface, the number of opposed segments to which the connection terminals are electrically connected in each connection terminal group is reduced. Therefore, even when the number s of commutator segments is set to the maximum number satisfying s = n × p / 2 as in the present invention, the opposing segments can be electrically connected in each connection terminal group. Here, the expression “connecting terminal group” includes a case where the connecting terminal group includes a single connecting terminal.

  In the invention of claim 5, when the power supply voltage is E [V], the number of commutator segments is s, and the number of permanent magnets is p, E / (s / p) ≦ 5 [V] is set. Yes. Here, since s / p = n / 2 from s = n × p / 2, E / (s / p) = E / (n / 2) ≦ 5 [V]. This formula represents the following. With the rotation of the armature, the + side brush and the − side brush are in contact with the two segments adjacent to each other in the rotation direction, and the + side brush is separated from one of the two segments. When n / 2 coils are connected between the brush and the negative side brush, the voltage applied to each of the n / 2 coils connected in delta connection is set to 5 V or less. ing. That is, at the moment when the segment that is in contact with the brush on the + side or − side is separated from the brush, the voltage change amount of the separated segment is set to 5 V or less.

Furthermore, the carbon brush used in the invention according to claim 5 has an effect of causing a voltage drop at a contact point with the segment. This voltage drop increases as the contact area decreases and becomes maximum just before the segment leaves the carbon brush. The ability of the voltage drop of carbon is about 5 V at the maximum regardless of the magnitude of the power supply voltage.
Therefore, by using a carbon brush and setting E / (s / p) = E / (n / 2) ≦ 5 [V], the voltage of the segment immediately before leaving the carbon brush and immediately after leaving the carbon brush Is substantially equal to the segment voltage. Therefore, when the segment leaves the carbon brush, the rectification between the commutator carbon brush and the commutator is improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
A fuel pump according to an embodiment of the present invention is shown in FIG. The fuel pump 10 includes a pump unit 20, a motor unit 30 as an electric motor that rotationally drives an impeller 26 of the pump unit 20, and an end support cover 14. The housing 12 surrounds the outer periphery of the pump unit 20 and the motor unit 30 and is a common housing for the pump unit 20 and the motor unit 30. The end support cover 14 covers the opposite side of the motor unit 30 from the pump unit 20 and forms a fuel discharge port 204.

  The pump unit 20 is a Wesco pump having a pump cover 22, a pump casing 24, and an impeller 26. The pump cover 22 and the pump casing 24 are case members that accommodate the impeller 26 rotatably. A C-shaped pump flow path 202 is formed between the pump cover 22 and the impeller 26 and between the pump casing 24 and the impeller 26. The fuel sucked from the suction port 200 provided in the pump cover 22 is pressurized in the pump flow path 202 by the rotation of the impeller 26, passes between the permanent magnet 32 of the motor unit 30 and the armature 40, and is discharged from the discharge port. 204 is discharged.

Four permanent magnets 32 formed in a quarter arc shape are attached to the inner peripheral wall of the housing 12 at equal intervals. The permanent magnet 32 forms four magnetic poles having different poles in the rotation direction.
A commutator 70 is assembled on the opposite side of the armature 40 from the pump unit 20. The permanent magnet 32, the armature 40, the commutator 70, and the brushes 120 and 122 (see FIG. 3) constitute a DC motor. A shaft 41 as a rotating shaft of the armature 40 is supported by a bearing member 18 that is accommodated and supported in the pump casing 24 and the bearing holder 16. The end of the armature 40 on the pump unit 20 side is entirely covered with the resin 66. By covering with the resin 66 in this way, the rotational resistance of the armature 40 rotating in the fuel is reduced, and the entry of foreign matter into the armature 40 is prevented.

As shown in FIG. 2, the armature 40 has a central core 42 at the center of rotation. The shaft 41 is press-fitted into the central core 42. The central core 42 is formed in a cylindrical shape having a hexagonal cross section, and has a recess 44 extending in the direction of the rotation axis on each of the six outer peripheral walls. The width of the recess 44 becomes narrower toward the outer side in the radial direction.
The six teeth 50 are installed on the outer periphery of the central core 42 in the rotational direction. Each tooth 50 includes a coil core 52, a bobbin 60, and coils 62 and 63 formed by winding a winding around the bobbin 60.

  The coil core 52 is a separate member from the central core 42. The coil core 52 has an outer peripheral portion 54 facing the permanent magnet 32 along the rotation direction, and a coil winding portion 56 extending from the outer peripheral portion 54 toward the central core 42. In the cross section orthogonal to the shaft 41 of the armature 40, the coil core 52 is formed in a T shape. The outer peripheral surface 55 of the outer peripheral part 54 is formed in a smooth convex arc shape. The size of the gap formed between the outer peripheral surface 55 of the outer peripheral portion 54 and the inner peripheral surface 33 of the permanent magnet 32 along the rotation direction is uniform. The coil winding portion 56 has a convex portion 58 extending along the shaft 41 on the central core 42 side. The convex portion 58 is wider toward the central core 42 side. The concave portion 44 and the convex portion 58 are fitted to each other by inserting the other into one of the concave portion 44 or the convex portion 58 from one side of the shaft 41.

  The bobbin 60 covers the coil core 52 except for the outer peripheral surface 55 and the convex portion 58 of the outer peripheral portion 54. The bobbin 60 magnetically insulates the outer peripheral portions 54 of the coil cores 52 adjacent to each other in the rotation direction. In the cross section orthogonal to the shaft 41 and the cross section including the shaft 41, the bobbin 60 forms a trapezoidal winding space whose width decreases from the outer peripheral portion 54 side toward the central core 42 side with the coil winding portion 56 interposed therebetween. . A total of six coils 62 and 63 are formed by winding the winding in this winding space. As shown in FIG. 3A, the six coils 62 and 63 are delta-connected in a ring shape. The arrows on the coils 62 and 63 shown in an annular shape in FIG. 3B indicate the winding direction of the coils 62 and 63. That is, the coils 62 and 63 adjacent in the rotation direction are wound in the opposite direction. As shown in FIG. 1, the start and end of each of the coils 62 and 63 are electrically connected to a terminal 64 on the commutator 70 side.

  As shown in FIG. 1, the commutator 70 includes a structure body 100 and a structure body 110. The structure 100 has a plurality of segments 72 installed in the rotation direction. Here, assuming that the number of the segments 72 is s, the number of the permanent magnets 32 is p, and the number of the coils 62 and 63 of the armature 40 (the number of teeth 50) is n, the segment 72 has s = n × p / 2. The maximum number represented by can be installed. In this embodiment, since n = 6 and p = 4 as described above, a maximum of 12 segments 72 are provided in the rotational direction.

  The segments 72 are made of, for example, carbon, and the segments 72 adjacent to each other in the rotation direction are electrically insulated by a gap and an insulating resin material. Further, as shown in FIG. 3B, S1 and S7, S2 and S8, S3 and S9, S4 and S10, S5 and S11, and S6 and S12, which are opposing segments installed on the opposite side in the radial direction, Each is electrically connected.

  The structure 100 is configured by insert-molding a segment 72, an intermediate terminal 80, and connection terminals 82 and 84 with a resin 74. The three connection terminals 84 are formed in a spiral shape, and the opposing segments are electrically connected at both ends. The structure 110 is formed by insert-molding the connection terminals 86 and 88 with a resin 112. The three connection terminals 88 are formed in a spiral shape, and the opposing segments are electrically connected at both ends. The intermediate terminal 80 and the connection terminals 82 and 84 of the structure 100 electrically connect the opposing segments of the segments 72 that are installed every other piece in the rotation direction. The connection terminals 86 and 88 of the structure 110 electrically connect the opposing segment to which the structure 100 is electrically connected and the opposing segment shifted by one in the rotation direction. The connection terminal group formed by the intermediate terminal 80 and the connection terminals 82 and 84 of the structure 100 and the connection terminal group formed by the connection terminals 86 and 88 of the structure 110 are disposed so as to be shifted in the axial direction.

  The connection of the structures 100 and 110 by the connection terminal group is performed outside the shaft 41 in the radial direction while avoiding the shaft 41 at the center. The coils 62 and 63 are delta-connected by assembling the commutator 70 in which the structure 100 and the structure 110 are assembled to the armature 40. That is, the connection terminal group of the structures 100 and 110 serves as a terminal for electrically connecting the opposing segments and a terminal for delta connection of the coils 62 and 63.

  Since the coils 62 and 63 adjacent to each other in the rotation direction are wound in the opposite direction, the coils a1 and b1 adjacent to each other in the rotation direction are supplied by supplying a current as shown by an arrow in FIG. Different magnetic poles are generated. Further, since the opposing segments are electrically connected, the configuration is the same as the configuration in which the other brushes 120 and 122 exist at the dotted line positions in FIG. Therefore, current also flows through the coils a2 and b2 located on the opposite sides of the coils a1 and b1 in the radial direction, and different magnetic poles are generated between the coils a2 and b2. Thereby, the couple which rotates the armature 40 on the radial direction opposite side of the armature 40 is generated.

  The brushes 120 and 122 are each made of carbon, the brush 120 is a positive side brush, and the brush 122 is a negative side brush. At locations where the brushes 120, 122 and the segment 72 are in contact, the rotation direction width of the brushes 120, 122 is set to be equal to or less than the rotation direction width of the segment 72. That is, the number of the brushes 120 and 122 contacting the segment 72 continuous in the rotation direction is up to two.

Next, a change in the segment voltage accompanying the rotation of the armature 40 will be described using the segment S5 (see FIG. 3B) as an example. FIG. 5A shows a change in the segment voltage in S5. The power supply voltage is 12V.
In the state shown in FIG. 3B and FIG. 4A, the segment voltage of S5 is set to 0 V shown in the vicinity of 0 ° of the mechanical angle and electrical angle in FIG. When the armature 40 rotates in the direction of rotation shown in FIG. 3B and S5 leaves the brush 122 and enters the state shown in FIG. 4B, a power supply voltage of 12V is applied to the coils a1, b1, and c1, As shown in FIG. 5A, the segment voltage applied to S5 by the power supply voltage is 4V.

  Here, a voltage drop due to contact resistance occurs at the contact portion between the carbon brush 122 and the segment 72. This voltage drop increases as the contact area between the brush 122 and the segment 72 decreases. Since the carbon brush 122 is capable of voltage drop of about 5V at the maximum, in the configuration of the present embodiment in which the segment voltage applied to S5 from the power supply voltage is 4V in the state shown in FIG. The segment voltage of S5 immediately before leaving the brush 122 rises to 4V due to the voltage drop effect of the brush 122. In this state, even if S5 is separated from the brush 122 and enters the state shown in FIG. 4B, the segment voltage applied to S5 by the power supply voltage remains 4V. Rectification between the brush 122 and the brush 122 can be improved.

When the armature 40 further rotates and the voltage of the brush 120 is applied to S6 and S7 due to the opposing connection, the segment voltage of S5 is 6V as shown in FIG. 5A, as shown in FIG. Become.
When the armature 40 rotates and the voltage of the brush 120 is applied only to S6 due to the opposing connection, the segment voltage of S5 becomes 8V as shown in FIG. 5A.

When the armature 40 rotates and the voltage of the brush 120 is applied only to S6 due to the opposing connection, the segment voltage of S5 becomes 8V as shown in FIG. 5A.
When the armature 40 rotates and the voltage of the brush 120 is applied to S5 and S6 due to opposing connection, the segment voltage of S5 becomes 12V as shown in FIG. 5A, as shown in FIG. .
When the armature 40 further rotates, the segment voltage of S5 decreases sequentially as shown in FIG. Hereinafter, as the armature 40 rotates, S5 repeats the change of the segment voltage shown in FIG. In the other segments 72, the segment voltages change similarly.

  In contrast to the present embodiment, the number of coils 62 is six and the number of permanent magnets 32 is four, which is the same as that of the present embodiment. FIG. 6 shows a comparative electric motor in which the coils are star-connected. Since the coil 62 is star-connected, the number of segments 72 is six. All six coils 62 are wound in the same direction. Hereinafter, the change in the segment voltage in the comparative example will be described by taking the segment S4 as an example. FIG. 5B shows changes in the segment voltage in S4. The power supply voltage is 12V. In FIG. 7, the coils a2, b2, and c2 are omitted for simplicity of explanation.

In the state shown in FIG. 6B and FIG. 7A, the segment voltage in S4 is 0 V shown in the vicinity of 0 ° of the mechanical angle and electrical angle in FIG. When the armature 40 rotates and S4 leaves the brush 122 and enters the state shown in FIG. 7B, the segment voltage applied to s4 by the power supply voltage of 12V becomes 6V.
When the armature 40 further rotates and the voltage of the brush 120 is applied to S4 and S5 due to the opposing connection, the segment voltage of S4 becomes 12V.

When the armature 40 further rotates, the segment voltage of S4 decreases sequentially as shown in FIG. Hereinafter, as the armature 40 rotates, S4 repeats the change of the segment voltage shown in FIG. In the other segments 72, the segment voltages change similarly.
In the comparative form, the number of coils 62 and the number of permanent magnets 32 are the same as in this embodiment, but the amount of change in the segment voltage is reduced by connecting the coils 62 in a star connection and the number of segments 72 is six. As shown in FIG. 5B, the voltage is 6V.

  In contrast, in this embodiment, the coils 62 and 63 are delta-connected and the number of the segments 72 is twelve, so that the amount of change in the segment voltage is reduced to 4 V at the maximum. As a result, the number of coils 62 and the number of permanent magnets 32 are the same as in this embodiment, but the amount of change in segment voltage is smaller than in the comparative embodiment in which the coils 62 are star-connected and the number of segments 72 is reduced. Yes. Therefore, even when the inductance of the coils 62 and 63 increases due to the concentrated winding of the coils 62 and 63, the rectification property when the segment 72 moves away from the brushes 120 and 122 can be improved.

Further, in the present embodiment, as described above, the change in the segment voltage is made almost zero immediately before and after the segment 72 is separated from the brushes 120 and 122 by using the action of the voltage drop at the carbon contact portion. . Thereby, the rectification | straightening property when the segment 72 leaves | separates from the brush 120,122 can be improved.
In addition, since the brushes 120 and 122 are in contact with only two segments 72 that are continuous in the rotation direction, the number of coils 62 and 63 connected between the brush 120 and the brush 122 can be increased as much as possible. Thereby, the change amount of the segment voltage of each segment 72 which contacts the brush 120,122 with rotation of the armature 40 can be reduced.

  In the present embodiment, the number n of the coils 62 and 63 is 6, and the number p of the permanent magnets 32 is 4, and the relationship of n = p + 2 is satisfied. In an electric motor, it is desirable that the number n of coils and the number p of permanent magnets (the number of magnetic poles of permanent magnets) are close to each other. This is to prevent it. Further, if the number n of coils is smaller than the number p of permanent magnets, torque fluctuation increases when the armature rotates, so that this is prevented.

Further, in this embodiment, the connection terminal groups of the structures 100 and 110 are installed so as to be shifted in the axial direction, so that the maximum number s of the segments 72 satisfies s = n × p / 2 as in this embodiment. Even if it becomes a structure which becomes number, an opposing segment can be electrically connected in each connection terminal group.
In addition, the connection terminals of the structures 100 and 110 also serve as connections for the coils 62 and 63, and the coils 62 and 63 are delta-connected by assembling the commutator 70 and the armature 40. The wiring work is easy. Further, the number of parts for connecting the coils 62 and 63 can be reduced.

(Other embodiments)
In the above embodiment, the number p of the magnetic poles formed by the permanent magnet 32 is 4, the total number of coils 62 and 63 (the number of teeth 50) n is 6, and the number of segments 72 from s = n × p / 2. Although s is set to 12, in addition to this, as long as s = n × p / 2 is satisfied, the number p of the magnetic poles formed by the permanent magnets may be an even number, and the number of teeth is other than 6. The number of It is desirable that the number n of coils and the number p of magnetic poles formed by the permanent magnet satisfy n = p + 2.

In the above embodiment, the brushes 120 and 122 and the segment 72 are made of carbon. However, for example, a brush and a segment made of copper other than carbon may be used.
In the above embodiment, the winding directions of the coils 62 and 63 adjacent to the rotation direction are reversed, and different magnetic poles are generated. However, the winding direction of the coils is the same, and the rotation is performed by changing the connection of the connection terminals. Different magnetic poles may be generated by reversing the current flowing in the coils adjacent in the direction.

Moreover, in the said embodiment, the suction input which suck | inhales a fuel generate | occur | produced when the impeller 26 as a rotation member of the pump part 20 rotates. In addition to the impeller, a configuration such as a gear pump may be employed as the rotating member of the pump unit.
Moreover, although this embodiment demonstrated embodiment which applied this invention to the fuel pump, this invention may be applied not only to this but to various electric motors.
As described above, the present invention is not limited to the above-described embodiment, and can be applied to various embodiments without departing from the gist thereof.

Sectional drawing which shows the fuel pump by one Embodiment. II-II sectional view taken on the line of FIG. (A) is a schematic diagram which shows the delta connection of a coil, (B) is a schematic diagram which shows the connection state of a segment and a coil. Explanatory drawing which shows the rotation state of the armature by the delta connection of this embodiment. The characteristic view which shows the change of the segment voltage by the delta connection of this embodiment, (B) is the characteristic figure which shows the change of the segment voltage by the star connection of a comparison form. (A) is a schematic diagram which shows the star connection of a coil, (B) is a schematic diagram which shows the connection state of a segment and a coil. Explanatory drawing which shows the rotation state of the armature by the star connection of a comparison form.

Explanation of symbols

10: Fuel pump, 20: Pump part, 30: Motor part (electric motor), 32: Permanent magnet, 40: Armature, 50: Teeth, 62, 63: Coil, 70: Commutator, 72: Segment, 80: Intermediate Terminal (connection terminal), 82, 84, 86, 88: Connection terminal (connection terminal), 120, 122: Brush

Claims (6)

Permanent magnets that are installed on the circumference and alternately form a plurality of magnetic poles with different poles;
An armature having a plurality of coils installed in a rotating direction, and rotatably installed on an inner peripheral side of the permanent magnet;
Brush and
A commutator that is electrically connected to the coil, rotates with the armature, and rectifies a current supplied to the coil by contacting the brush, and is divided into a plurality of segments in the rotation direction and adjacent to each other. Commutators in which the segments are electrically isolated from each other;
With
The coils are concentratedly wound and delta-connected to each other, and at the contact point between the brush and the commutator, the rotation direction width of the brush is equal to or less than the rotation direction width of the commutator segment, An electric motor in which s = n × p / 2, where s is the number of segments, p is the number of permanent magnets, and n is the number of coils.   2. The electric motor according to claim 1, wherein n = p + 2, where p is the number of permanent magnets and n is the number of coils.   3. The electric motor according to claim 1, wherein an angle interval between the brush on the + side and the brush on the − side is 360 ° / p, where p is the number of the permanent magnets.   A plurality of the commutators are installed on the armature side, and are connecting terminals that electrically connect the segments of the commutator installed on the opposite side in the radial direction, the shaft of the armature The electric motor according to any one of claims 1 to 3, further comprising a connection terminal that constitutes a plurality of connection terminal groups installed so as to be displaced in a direction.   2. The brush is a carbon brush, and E / (s / p) ≦ 5 [V], where E [V] is a power supply voltage, s is the number of segments, and p is a number of the permanent magnets. 5. The electric motor according to any one of items 1 to 4. An electric motor according to any one of claims 1 to 5,
A pump unit for generating a suction input for sucking fuel by a rotational driving force of the electric motor;
With fuel pump.

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