JPS5921268A - Manufacture of magnet field stator - Google Patents

Abstract

PURPOSE:To improve the yield of manufacturing a magnet field stator by associating and polishing the radius a main pole to the inner peripheral surface of the main pole of a permanent magnet mounted on the inner peripheral surface of a cylindrical yoke smaller by the prescribed amount than the prescribed size and the radius of an auxiliary pole larger than the prescribed size of the main pole. CONSTITUTION:Auxiliary poles 4 made of soft iron and a main pole 3 made of permanent magnet are mounted inside a cylindrical yoke 2 forming a stator 1 of a DC rotary machine. The radius D to the inner peripheral surface of the main pole 3 is reduced by delta smaller than an air gap (d) between a rotor 5 and the stator 1 from the final prescribed size Dp. The radius Ds to the inner peripheral surface of the auxiliary pole 4 is formed slightly larger than the size Dp. Then, it is cut by a tool on which diamond abrasive is coated, the pole 3 made of permanent magnet is polished to form the prescribed radius Dp, thereby forming the prescribed air gap (d). In this manner, the magnet 3 which is hard and brittle is polished in high yield, thereby preventing the clogging of the tool due to the cutting chips of the soft iron of the pole 4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a magnet field stator for a DC machine in which a permanent magnet is used as a main pole and soft iron auxiliary poles are arranged in parallel.

In a DC machine used for starting a 1-ton engine, etc., for an internal combustion engine, as shown in FIG. It is known that the torque characteristics can be improved by attaching the auxiliary magnetic poles 4 adjacent to each other. In such a known magnet field type DC machine stator, the auxiliary magnetic pole 4 is generally formed by drawing or cold forming a soft iron material, and due to the material, sufficient machining accuracy is required for machining it to desired dimensions. There is no particular difficulty in obtaining it. However, ferrite magnets, which are commonly used as permanent magnets for the main magnetic pole 3, are extremely hard and brittle, as is known from the name ceramic magnets, and therefore require special processing using a cutting tool coated with diamond abrasive grains. Become. By such special processing, the outer and inner circumferential surfaces of the main pole 3 are finished to the desired dimensions before being attached to the yoke 2, and then the outer and inner circumferential surfaces of the main pole 3 are finished to the desired dimensions. The auxiliary magnetic poles 4 and the auxiliary magnetic poles 4 are fixed adjacent to each other on the inner circumferential surface of the yoke 2. However, due to machining errors due to the special machining mentioned above, the tolerances of the outer and inner circumferential surfaces of the main pole 3, the ridges,
There is a risk that various tolerances such as cylindricity will accumulate and the inner diameter of the main pole 3 will become smaller than the outer diameter of the armature 5, making it impossible to insert the armature 5 into the stator 1. The inner diameter of the main magnetic pole 3 must be increased by an amount corresponding to the accumulated tolerance. This causes the air gap distance d between the surface of the armature 5 and the inner circumferential surface of the main pole 3 to become an excessive value exceeding the original minimum distance necessary to prevent contact between the two surfaces. As is well known, an increase in the air gap distance d means an increase in the magnetic resistance of the air gap distance d, which accounts for most of the total magnetic resistance in the magnetic circuit excited by the field poles. Therefore, the magnetic flux in the magnetic path Lack of density 1 - Magnetic flux decreases inversely, reducing torque.

In other words, the torque characteristics improved by the provision of the auxiliary magnetic pole are greatly diminished due to the decrease in the number of magnetic fluxes due to the increase in the air gap distance. Furthermore, the effect of reducing the demagnetizing effect of the armature reaction by this auxiliary magnetic pole attachment method is also largely negated by the decrease in magnetic flux sealing due to the increase in the air gap distance, resulting in the risk of irreversible demagnetization of the permanent magnet. .

The present invention solves the drawbacks of the conventional DC machine field system as described above.
:59! The object of the present invention is to provide a method for manufacturing a stator, which has the characteristics described in the claims section. Hereinafter, the method of the present invention will be briefly explained with reference to FIG. 3. The numbers 1 to 5 in the figure are the first
The same parts as the numbers in the figure are shown. First, the inner periphery of the yoke 2 of the stator l] was finished to the specified dimensions, and the auxiliary magnetic pole 4 made of a soft iron material by drawing or cold forming, and the main magnetic pole 3 made of a fired ferrite magnet. The outer and inner circumferential surfaces of each item are finished to a fixed size by cutting or grinding. Next, the finished main magnetic pole 3 and auxiliary magnetic pole 4 are fixed to the inner peripheral surface of the yoke 2 with their respective outer peripheral surfaces adjacent to each other along the rotational direction of the armature 5. A cross section of the stator 1 having the field poles formed in this way is shown in FIG. (dashed line) is D, the inner diameter fDs of the auxiliary magnetic pole 4, the diameter of the armature 5, and the predetermined air gap distance is d, and d=Dp, D, -D-δ.

After the main magnetic pole 3 and the auxiliary magnetic pole 4 are attached to the yoke 2 adjacent to each other as described above, the inner peripheral surface of the main magnetic pole 3 is ground by a thickness δ using a special tool to which the diamond abrasive grains are attached. As a result, the inner diameter of the main magnetic pole 3 is ground to Dp,
The difference between the inner diameter of the ground main pole 3 and the diameter of the armature 5, that is, the air gap distance, is determined by the above relationship Dp-
D, = d. In addition, the auxiliary magnetic pole 4 can be attached to the yoke 2 by machining before the process) By making its inner diameter Ds slightly larger than the inner diameter of the main magnetic pole 3 after the above-mentioned grinding, the auxiliary magnetic pole 4 can be finished. This prevents the relatively soft soft iron surface from being ground by the grinding tool of the main magnetic pole 3, and prevents the tool from being damaged due to clogging between the diamond abrasive grains of the grinding tool with soft iron cutting powder. .

As mentioned above, when machining the main pole 3 before attaching it to the yoke 2, the inner diameter of the main pole 3 is made smaller than the final finished dimension by the pre-predicted grinding thickness δ. For attachment to the iron 2, when the subsequent grinding thickness becomes δ, the air gap distance to the armature 5 becomes a predetermined distance d. In other words, at the time the main magnetic pole 3 is attached to the yoke 2, due to the difficulty of machining the permanent magnet material, the installation process is based on how the finishing tolerances of each part dimension, cylindricity, etc. Even if the main pole 3 is installed, the inner circumferential surface of the main pole 3 can be machined so that the inner diameter takes into account the grinding thickness δ that can accommodate this total stacking tolerance. The inner diameter is installed by later grinding, and when the diameter is enlarged to the point where the gap distance between the inner circumferential surface of the main magnetic pole 3 and the surface of the electrode element 5 inevitably matches the initially set value d. .

In the present invention, as described above, the air gap distance d can always be accurately matched to a desired set value regardless of the accumulation of manufacturing and installation tolerances of the main magnetic pole 3, and undesirable values of the d value can be avoided. It was possible to completely prevent the increase in As a result, problems such as a decrease in magnetic flux density due to an increase in the air gap distance and a corresponding decrease in output or torque as described in the conventional example are solved, and the auxiliary magnetic pole 4 This made it possible to prevent irreversible demagnetization caused by the slave unit reaction magnetic effect being canceled by the demagnetization effect due to the increase in air gap distance.

As an example of the DC machine according to the present invention, the outer diameter of the yoke 2 is 68 m.
m,! Situation 5: Iron core thickness 45 mm, inner diameter of main pole 3,
According to the experimental results when the dimensional difference Q between the inner diameter Ds of the auxiliary magnetic pole 4 and the inner diameter Ds of the auxiliary magnetic pole 4 is 1 mm, the air gap distance d is set to 0.
By being able to reduce it to 5-1.0 mm f 0.4-0.5, the output improvement due to the increase in magnetic flux density was 6.7X.
The result was that the demagnetization resistance was improved by 7%.

FIG. 2 shows an analytical diagram of the excitation operation of the permanent magnets in response to an external demagnetizing field acting as a 'wt machine machine reaction in a DC machine using the main magnetic pole 3 and the auxiliary magnetic pole 4 according to the method of the present invention. The residual magnetic flux density of the permanent magnet used for the main magnetic pole 3 is BrH
The holding force is HC and iHc, and the B-H characteristic and 4π
The I-H characteristics are shown in the B-8 curve and 4πI-
8 curves. Assuming that the operating line k P c is determined by the total magnetic resistance of the magnetic circuit of this DC machine, in the case of the method of the present invention, the magnetic resistance at the air gap distance d, which accounts for most of the above total magnetic resistance, is small, so the above operating line The angle θ of Pc with respect to the magnetic flux density B axis is small, and the Pc curve is B-
8 curve intersects at point A, and the corresponding magnetic flux density is B
a 1 , the point on the 4πI-H curve corresponding to point A is point B.

Next, if a demagnetizing field ΔH acts due to the armature reaction accompanying the rotation of the armature 5, the permanent magnet operating line will pass through A-+B-+C:D along the arrow in the figure, and the demagnetizing field will be applied. After removing it, it returns to point A along the B-H curve, so the magnetic flux density is 13
No change from d. In other words, no magnetic impermeability occurs.

On the other hand, in the case of the conventional method shown in FIG. 1, the angle θ of the operating line Pc with respect to the B axis is large as shown in FIG. intersect at point a, and the magnetic flux density at this time is Bd,,4
The point corresponding to point a on the πl-H curve is b. Point o,
If the motion aPI passing through b is the intersection point kc of the motion line P'+ and the 4πI-8 curve, which is translated by the armature reaction ΔH, and the point on the B-H curve corresponding to C is d, then the point d is B After the demagnetizing field is removed via point 3d to reach the downward curve of the -8 curve, the operating point is not on the B-8 curve but on the path indicated by the arrow d-a' in the figure. Move to point a' on line Pc, which is different from point a.

Therefore, the magnetic flux density Bd for the point a on the initial operating line Pc is equal to the magnetic flux density Bd for the point a', and irreversible demagnetization occurs by the difference between the subtraction Bd and Ba. Such irreversible demagnetization can be prevented by the method of the present invention as described above.

[Brief explanation of drawings]

1 and 4 respectively show a cross-sectional view and an excitation operation analysis diagram of a conventional example, and FIGS. 2 and 3 respectively show a cross-sectional view f and an excitation operation analysis diagram of an embodiment of the method of the present invention. 1...Stator%2 River yoke, 3...Main magnetic pole, 4...
Auxiliary magnet No. l Figure 3 Eyes 4. mouth

Claims (1)

[Claims] 1. On the annular inner peripheral surface of the DC machine stator yoke, the main magnetic pole of the permanent magnet and the auxiliary magnetic pole of soft iron are mutually VW! In the process of forming a stator having field poles that are fixed in contact with each other, the inner diameter DB of the auxiliary magnetic pole is adjusted in advance to the diameter of the armature and the predetermined gap IJJ distance d before installation to the yoke. The sum Dp with twice
(=D, 10d), and the inner diameter Dk of the main pole is made smaller by at least the planned grinding thickness δ, so that the main pole and the auxiliary pole are A method for manufacturing a magnet field stator, characterized in that the inner diameter of the main pole is ground until the inner diameter of the main pole, which is fixed to the inner circumferential surface of the stator in contact with the main pole, is rounded.