JPS63305741A - Pawl shape of rotor core structure for automotive generator - Google Patents

Abstract

PURPOSE:To reduce loss and to enhance the output of a generator by reducing the overlap of the pawl of a rotor core with a stator core to a specific amount or less, and determining the ratio of the end width to the base width of the pawl in a given range. CONSTITUTION:A rotor core 3 has a convergent pawl 3b protruding and having a reduced length to overlap with a stator core 6 axially is short so that the lap rate may become smaller than 1. Further, the width of the end of the pawl 3b in the shaft circumferential direction is so set that the rate of the width to the width of the base in the shaft circumferential direction falls in a range of approx. 0.20-0.45. Thus, the shape of the pawl 3b of the core 3 can be formed in an ideal shape, thereby reducing the weight and enhancing the output. Further, the vibration of the pawl 3b is suppressed to reduce a noise.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the shape of a claw portion of a rotor core in a vehicle generator mounted on a vehicle such as a passenger car, bus, truck, or two-axle motor vehicle.

[Prior art and problems to be solved by the invention] Generally, in this type of vehicle generator (alternator),
Some rotor cores, around which rotor coils are wound, are rotatably supported on the inner circumferential side of a stator coil fixed to the case bracket.

However, in the past, the rotor core was constructed so that the tips of the claws coincided with the side ends of the stator coils, as shown in FIG. Not only does the weight become heavier, but when the rotor core rotates at high speed, the claws receive a large centrifugal force and become distorted outward. Therefore, it is necessary to increase the gap between the claws and the inner periphery of the stator core to prevent the claws from coming into contact with the stator core, which is an obstacle to achieving high output. Furthermore, the ends of the claws vibrate due to the alternate opposition between the teeth and slots of the stator core, which is a cause of increased noise.

Furthermore, the claws (balls) of the rotor core are tapered and protrude in the axial direction, but conventionally,
There was no study on the relationship between the tip width and the base width of the core claw, and the relationship was determined based solely on experience.In today's world, where there is a strong demand for increased output in addition to size reduction, it is the most appropriate method. It is extremely meaningful to consider the shape of the claw.

[Means for Solving the Problems] In view of the above-mentioned circumstances, the present invention was created for the purpose of providing a shape of a claw portion of a rotor core in a created vehicle generator.

In a vehicle generator including a rotor core rotatably provided with a tapered core claw portion protruding in the axial direction formed inside the stator coil, the core claw portion overlaps with the stator coil in the length direction. It is characterized by being short so that the ratio is less than 1, and the ratio of the width of the tip to the width of the base in the axial direction is set to be within the range of approximately 0.20 to 0.45. be.

With this configuration, the present invention makes the shape of the core claw part an ideal shape with less loss even during high-speed rotation,
This makes it possible to achieve high output even when rotating at low speeds.

[Example] Next, an embodiment of the present invention will be described based on the drawings.

In the drawings, reference numeral 1 denotes a generator for a vehicle, and the generator 1 includes a so-called rundle-type rotor core 3. which is press-fitted into a core shaft 2 with claws 3b facing each other. A coil bobbin 4 is installed inside the rotor core 3, and a rotor coil 5 is wound around the coil bobbin 4. A stator 6 around which a stator coil 6a is wound, a brush 7 that is compressively housed in a brush holder 7a, a slip ring 8 on which the brush 7 slides, a rectifier 9 that rectifies the generated alternating current, and a cooling fan 3
The construction of various members such as a is the same as before.

The rotor core 3 is shown in FIGS. 2(a) and 2(b).

As shown in FIGS. 3(A) and 3(B), a plurality of core claws 3b at the tip edge of the outer periphery are formed to protrude in a tapered shape in the axial direction, and the outer peripheral surface of the core claws 3b forms the stator coil 6a. The inner peripheral surfaces of the two are rotated facing each other with a predetermined gap between them.

Now, if the axial length of the stator coil 6a (stator lamination thickness) is taken and the length of the portion of the core claw portion 3b opposite to the stator lamination thickness is Q, then the wrap ratio α is α=fi/L.
is given by Then, samples with various wrap ratios α were prepared, and the amount of strain H (amount of outward expansion) of the core claw portion 3b and the output current A were actually measured. (In this experiment, the taper ratio β described later was carried out at 0.30.) The results are shown in Figs. 5 and 6, and the rotor core 3 was rotated at high speed (20,000 rpm). ■) It was found that the amount of strain H in the core claw portion 3b decreases almost linearly as the wrap rate α becomes smaller.On the other hand, as for the output current A, when the engine is idling, When rotating at a low speed (2,000 rpm) assuming that From this, when the length Q of the core claw portion 3b is shortened to a limit of approximately 0.88 for the overlap ratio α between the stator coil 6a and the core claw portion 3b, the amount of claw distortion H
decreases, but it can be said that the output current does not decrease. Therefore, the core claw portion 3b can be made shorter than the conventional one to achieve weight reduction, and the gap between the stator coil 6a and the core claw portion 3b can be reduced to improve efficiency. Note that Q, Q2, H, and H2 in the figure are the length and strain amount of the core claw portion when the wrap ratio α is 1.00 and 0688, respectively.

The reason why the output current A does not decrease even if the core claw portion 3b is shortened in this way is that the decrease in magnetic flux due to the shortened core claw portion 3b is caused by This is thought to be due to the fact that the magnetic flux is compensated for by the magnetic flux path leading to 6a.

Next, when the width of the tip portion 3c of the core claw portion 3b is W and the width of the claw base (base portion) 3d is W, the taper rate β is β=
It is given by w/W. Therefore, core claw parts with different values of taper ratio β were prepared by keeping the claw base width W as the same and varying the tip width W.

The correlation between the taper ratio β and the output current A at low speed rotation (2,000 rpa+) was measured. The results are shown in Figure 7, where the highest output current A was vA8111 when the taper ratio β was approximately 0.35, and it was observed that the output decreased before and after this peak. . In practical terms, the taper ratio β needs to be within the range of approximately 0.20 to 0.45, considering the output current value required in the low-speed rotation range (specifically, approximately 42 amperes or more). By doing so, it is possible to provide an extremely efficient and high-output device in a lightweight and compact manner.

[Operations and Effects] In short, 1. Since the present invention is configured as described above, the length of the core claw portion can be shortened to reduce weight, and the amount of distortion of the rotor core during high-speed rotation can be suppressed to a small level. By setting the ratio of the tip width to the base width in the axial direction of the core claw in the range of approximately 0°20 to 0.45, it is possible to set the output current to the peak value, thus achieving excellent light weight and high output. can be achieved. Further, vibration of the claw portion of the rotor core can be suppressed and noise can be reduced.

[Brief explanation of drawings]

The drawings show an example of the shape of the claw portion of the rotor core in a vehicle generator according to the present invention, in which FIG. 1 is a cross-sectional view of the generator, and FIG. 2 (A) is a perspective view of the core claw portion. Figures 1 and (b) are cross-sectional views of the outer circumferential surface of the claw portion. Figure 3 (a) is a diagram of the flow of magnetic flux at α = 1.00 and (b) is a diagram of the flow of magnetic flux at α = 0.88, Figure 4 is an explanatory diagram showing the amount of distortion in the core claw, and Figure 5 is the wrap ratio. Relationship diagram between and amount of distortion, No. 6
The figure is a diagram showing the relationship between the wrap ratio and the output current, and FIG. 7 is the diagram showing the relationship between the taper ratio and the output current. In the figure, l is a generator, 3 is a rotor core, 3b is a core claw part,
6a is the stator coil, α is the wrap rate, β is the tapered rate, A
is the output current, l (is the amount of distortion of the core claw part, w and W are the width dimensions of the tip and base of the core claw part, respectively. Patent applicant: Mitsuba Electric Manufacturing Co., Ltd. No. 4
Figure b l91 beak construction-R-guidance

Claims (1)

[Claims] In a vehicle generator including a rotor core rotatably provided with a tapered core claw portion protruding in the axial direction formed inside the stator coil, the core claw portion overlaps with the stator coil in the length direction. For vehicles, characterized in that the ratio is set to be shorter than 1, and the ratio of the tip width to the base width in the axial direction is set within the range of approximately 0.20 to 0.45. The shape of the claw part of the rotor core in a generator.