JP2001298930A - Brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize cost reduction for a drive circuit of a brushless motor. SOLUTION: Ten armature coils A1, A2,..., El, E2 in total of a brushless motor 14 are equally divided into two power feeding groups G1, G2 and five armature coils are star-connected, respectively. Two drive circuits 40 are provided corresponding to two power feeding groups G1, G2 and power feeding to the armature coils is switched with discrete drive circuits 40 for every power feeding groups G1, G2. For example, when a motor of specification 4A is driven with the drive circuit 40 of specification 2A, it is enough to use two drive circuits 40 of the specification 2A and when the motor of specification 6A is driven, it is enough to use three drive circuits 40 of specification 2A. Moreover, when the motor of specification 2A is driven, it is enough to use only one drive circuit 40 of specification 2A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor having an improved driving system.

[0002]

2. Description of the Related Art For example, as shown in FIG. 6, a 5-phase 10-slot brushless motor has A-phase to E-phase armature coils A1, A2,... (Not shown), the ten switching elements 2 constituting the drive circuit 1 are sequentially switched according to the rotational position of the armature coils A1, A2,.
The magnet rotor is driven to rotate by sequentially switching the energization to E1 and E2.

[0003]

When the brushless motor having the above structure is used, for example, as a drive motor for a fuel pump, the required pump discharge capacity depends on the required pump discharge capacity.
A current of about 2 A to 4 A flows through each switching element 2 of the drive circuit 1. Therefore, when the driving circuit 1 is formed into one chip, it is conceivable that all the chips are set to the 4A specification and the cost is reduced by the mass production effect.

However, when the driving circuit 1 is integrated into one chip,
As the current increases, the chip size needs to be increased, which increases the cost. Therefore, 2A
In the fuel pump of the specification, the drive circuit of the 4A specification has excessive performance, which also causes an increase in cost.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a brushless motor capable of reducing the cost of a drive circuit.

[0006]

According to a first aspect of the present invention, there is provided a brushless motor in which an armature coil of each phase is divided into a plurality of energized groups and connected. The current supply to the armature coil is switched by a separate drive circuit. In this case, for example, when driving a 4A brushless motor with a 2A specification drive circuit, two 2A specification drive circuits may be used. Similarly, when driving a 6A specification brushless motor, a 2A specification brushless motor is used. What is necessary is just to use three drive circuits,
When driving a 2A specification brushless motor, only one 2A specification drive circuit may be used. In this way, it is not necessary to use an expensive drive circuit having a large rated current (heat generation amount) even for a brushless motor having a large rated current, and an inexpensive drive circuit having a small rated current is used as a common component. By simply changing the number, drive circuits for brushless motors with various rated currents can be configured, and cost reductions due to mass production effects can be achieved. Furthermore, for a brushless motor with a small rated current, reducing the number of drive circuits does not cause the drive circuit to have excessive performance, and a low-cost drive circuit with performance that matches the rated current of the brushless motor can be constructed. Can be.

In this case, it is preferable that each energization group connects the same number of armature coils. With this configuration, it is possible to configure a brushless motor drive circuit having various rated currents using only one type of drive circuit, and to increase the cost reduction effect.

It is preferable that each drive circuit is constituted by one IC chip.
In this case, the number of parts can be significantly reduced, the assemblability can be improved, and the cost can be further reduced.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a fuel pump of a vehicle will be described below with reference to FIGS.

First, the overall structure of the fuel pump 11 will be described with reference to FIG. The fuel pump 11 is configured by incorporating a brushless motor 14 and a pump unit 13 in a cylindrical housing 12. The structure of the pump section 13 will be described. A pump casing 15 and a pump cover 16 fixed to one end of the cylindrical housing 12 by press fitting, caulking, or the like.
A pump chamber is formed from the above, and the impeller 17 is housed in the pump chamber. The impeller 17 is fitted on a rotating shaft 24 of the brushless motor 14.

On the other hand, the brushless motor 14
This is a brushless motor having 10 slots per phase, and is configured as follows. A cylindrical stator 19 is fitted and fixed in the cylindrical housing 12.
As shown in FIG. 1, for example, ten teeth 51 to 60 (slots) are formed. These teeth 51-60
Include five-phase armature coils A1, A2,.
, E1 and E2 are mounted two by two in the order of A-phase, B-phase, C-phase, D-phase and E-phase, and two armature coils of each phase are symmetrical with respect to the rotating shaft 24 ( 180 ° opposite side)
Are located in

A 10-pole stator 1 constructed as described above
A magnet rotor 23 is arranged on the inner peripheral side of the magnet 9. The magnet rotor 23 includes a rotor core 25 fitted to a rotating shaft 24 and, for example, eight field magnets 26 fixed to the outer periphery of the rotor core 25 by bonding or the like. However, as shown in FIG. 1, N poles and S poles are arranged alternately. Thus, an eight-pole magnet rotor 23 is configured.

As shown in FIG.
One end of the rotating shaft 24 is rotatably supported by a bearing cylinder 28 at the center of the pump casing 15 via a bearing 27, and a bearing 29 supporting the other end of the rotating shaft 24 is fixed in the cylindrical housing 12. The bearing holder 30 is assembled. A drive control device 31 is mounted on the bearing holder 30. When the motor is driven, the drive control device 31 sequentially switches energization to the armature coils 21 of each phase. A housing cover 33 having a discharge port 32 is fitted in an opening of the cylindrical housing 12 on the drive control device 31 side.

The pump unit 1 is driven by a brushless motor 14.
When the impeller 17 is driven to rotate, fuel in a fuel tank (not shown) is sucked into a pump chamber from a suction port (not shown) of the pump cover 16 and a discharge port (not shown) of the pump casing 15. ) Is discharged into the cylindrical housing 12. This fuel flows through a gap between the stator 19 and the magnet rotor 23, is discharged from a discharge port 32 of the housing cover 33 into a fuel pipe (not shown), and is sent to a fuel injection valve (not shown).

Next, the armature coils A1, A2,.
, E1, E2 will be described with reference to FIG.
5-phase armature coils A1, A of brushless motor 14
, E1, E2 are equally divided into two energizing groups G1, G2, one for each phase. In one energizing group G1, five armature coils A1, B1, C1,
D1 and E1 are star-connected, and the other energization group G2
Then, the remaining five armature coils A2, B2, C2, D
2, E2 are star-connected. As described above, the two armature coils of each phase are arranged at positions symmetrical with respect to the rotation shaft 24 (at positions opposite by 180 °).

Two drive circuits 40 are provided corresponding to the two energization groups G1 and G2. The two drive circuits 40 have the same configuration of, for example, 2A specifications, and each includes ten switching elements T1 to T1 such as MOSFETs.
0 is incorporated in one IC chip. These ten switching elements T1 to T10 are connected in pairs in the form of a bridge between the power supply voltage side and the ground side, and an intermediate connection point of the two switching elements of each pair is star-connected. It is connected to one end of the A-phase to E-phase armature coils.

The two drive circuits 40 are simultaneously driven by a common drive signal output from one control unit (not shown). These two drive circuits 40 and one control unit are assembled in the drive control device 31 disposed inside the fuel pump 11 described above. The control unit detects the rotational position of the magnet rotor 23 by an induced voltage induced in the coil of the non-energized phase, and based on the detection signal,
As shown in FIG. 4, the switching elements T <b> 1 to T <b> 10 are sequentially switched to energize, for example, three-phase armature coils among the five phases, and the magnet rotor 23 is driven to rotate.

In this case, the two drive circuits 40 are simultaneously driven by a common drive signal output from one control unit (not shown), so that the two current-carrying groups G1,
The energized phase of G2 is the same. For example, in one energizing group G1, the A, B, and C phase armature coils A1, B1, C
In the case of energizing 1, the other energizing group G2 also
A, B and C phase armature coils A2, B2 and C2 are energized. Since the two armature coils of each phase are arranged at 180 ° opposite sides, respectively, two energization groups G1,
If the current-carrying phase of G2 is the same, the magnetic force generated between the armature coil of the current-carrying phase and the magnet rotor 23 opposed thereto is symmetric with respect to the rotation axis 24, and acts on the magnet rotor 23. The magnetic force can be a couple, and the force component acting in the radial direction of the magnet rotor 23 can be canceled. Thereby, the rotating shaft 2
4, the load applied to the bearing 27 can be reduced,
The durability can be improved, the run-out of the rotating shaft 24 can be prevented, and smooth rotation can be realized.

In the present embodiment described above, the armature coils of each phase are divided and connected to a plurality of energizing groups G1 and G2, and a separate drive circuit 40 is provided for each of the energizing groups G1 and G2.
Therefore, when driving the brushless motor 14 of the 4A specification by the drive circuit 40 of the 2A specification, for example, two drive circuits 40 of the 2A specification may be used. When driving a 6A-type brushless motor, three 2A-type drive circuits 40 may be used. When driving a 2A specification brushless motor, only one 2A specification drive circuit 40 may be used. In this way, it is not necessary to use an expensive drive circuit having a large rated current (calorific value) even for a brushless motor having a large rated current, and an inexpensive drive circuit 40 having a small rated current (calorific value) is used. By simply using the components and changing the number thereof, it is possible to configure drive circuits for brushless motors having various rated currents, and it is possible to reduce costs by mass production effects. In addition, for a brushless motor having a small rated current, the number of drive circuits 40 is reduced, so that the drive circuit does not have excessive performance, and a drive circuit having a performance corresponding to the rated current of the brushless motor is configured at low cost. be able to.

Further, in the present embodiment, the same number of armature coils are connected for each of the energizing groups G1 and G2, so that only one type of driving circuit 40 is used to drive brushless motors of various rated currents. Can be configured,
The cost reduction effect can be increased. However, in the present invention, the number of armature coils may be different for each of the energization groups G1 and G2.

In this embodiment, one armature coil is wound around each of the teeth 51 to 60 of the stator 19, but two or more armature coils are wound around each of the teeth 51 to 60, respectively. It may be turned and connected to separate drive circuits. Alternatively, the armature coils of each phase may be divided into three or more energization groups and connected, and the energization to the armature coils may be switched by a separate drive circuit for each energization group. Further, the connection method of the armature coils of each phase is not limited to the star connection, but may be a delta connection.

In this embodiment, the three-phase armature coils of the five phases are energized simultaneously. However, the four-phase or two-phase armature coils of the five phases are energized simultaneously. For example, the method of energizing the armature coil may be appropriately changed. Further, the number of phases of the armature coil is not limited to five, and may be four or less or six or more. Further, in the present embodiment, the drive control device 31 is disposed inside the fuel pump 11, but this may be disposed outside the fuel pump 11.

In addition, the present invention provides a magnet rotor 23
May be detected by a position detection element such as a Hall element, and the energized phase may be switched based on the detection signal. The scope of the present invention is the fuel pump 1
The present invention is not limited to one drive motor, and can be used as drive motors for various devices.

[Brief description of the drawings]

FIG. 1 is a sectional view taken along line FF of FIG. 5, showing one embodiment of the present invention.

FIG. 2 is a winding diagram illustrating a winding system.

FIG. 3 is a circuit diagram showing a connection relationship between an armature coil of each phase and a drive circuit.

FIG. 4 is a time chart showing a switching pattern of each switching element of the drive circuit.

FIG. 5 is a longitudinal sectional view of a fuel pump.

FIG. 6 is a circuit diagram showing a connection relationship between an armature coil of each phase and a drive circuit of a conventional brushless motor.

[Explanation of symbols]

11 fuel pump, 13 pump section, 14 brushless motor, 19 stator, 23 magnet rotor, 2
Reference numeral 6: magnet, 31: drive control device, 40: drive circuit, 51 to 60: teeth, A1, A2, B1, B2,
C1, C2, D1, D2, E1, E2 ... armature coils,
G1, G2: energization group, T1 to T10: switching elements.

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) BB08 TT01 TT02

Claims (3)

[Claims] 1. A brushless motor that rotates a magnet rotor by causing a stator having armature coils of each phase mounted thereon and a magnet rotor to face each other, and sequentially switching energization to the armature coils of the respective phases. A brushless motor characterized in that armature coils of each phase are divided and connected to a plurality of energization groups, and energization to the armature coils is switched by a separate drive circuit for each energization group. 2. The brushless motor according to claim 1, wherein the same number of armature coils are connected to each of the energizing groups. 3. The driving circuit according to claim 1, wherein each of the driving circuits includes one IC.
The brushless motor according to claim 1, wherein the brushless motor is configured by a chip.