Motor mounting plate

A motor mounting plate, composed of a metallic plate, includes: a disc-shaped plate body having a mounting portion to which a motor is mounted, and at least three flanges formed at a circumferential edge of the plate body, the flanges mounted at predetermined locations, an angle between adjacent flanges around the center of the plate body is 140° to 180°.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a motor mounting plate for mounting a motor at a predetermined location in apparatuses such as electrical equipment.

2. Related Art

In various electrical equipment such as office equipment, a motor such as a stepping motor is used as a driving source and is mounted at a predetermined location of a frame via a mounting plate in ordinary cases (See Japanese Patent Application, First Publication No. 2001-095191 and Japanese Patent Application, First Publication No. 2008-029175). As such a motor mounting plate, a plate produced by drawing a metallic plate and a plate composed of aluminum die-cast metal having high rigidity are provided. Furthermore, a motor mounting plate in which vibration can be reduced by using an antivibration rubber is known (See Japanese Patent Application, First Publication No. 2001-095191 and Japanese Patent Application, First Publication No. 2008-029175).

SUMMARY OF THE INVENTION

In a motor mounting plate composed of a metallic plate, resonance is caused by a rotation of a motor and vibration provided from the outside, and a plate portion is highly deformed by the resonance. For avoiding resonance, the relationship between number of slots and number of poles are individually designed so as to avoid values of natural vibration frequency of the mounting plate, or the natural vibration frequency must be designed so as to avoid the values of frequencies in which excitation force calculated from the number of the slots and number of the poles is large, so that complicated designing is required. Furthermore, an aluminum die-cast product is expensive and is unfavorable for cost reduction. When an antivibration rubber is used, the antivibration performance thereof varies according to the environment in which it is used, and the rubber degrades over time, so that use is limited and replacement maintenance is necessary.

The present invention was completed according to the above circumstances. An object of the present invention is to provide a technique in which, in amounting plate composed of a metallic plate having a relative cost advantage, resonance can be effectively inhibited even though it has simple design and structure.

A motor mounting plate composed of a metallic plate according to a first aspect of the present invention includes a disc-shaped plate body having a mounting portion to which a motor is mounted; and at least three flanges are formed at a circumferential edge of the plate body and are mounted at predetermined locations; in which one of the angles between adjacent flanges around the center of the plate body is 140° to 180°.

In the motor mounting plate according to a second aspect, one of the angles between the adjacent flanges around the center of the plate body is 160° to 180°.

In the motor mounting plate according to a third aspect, a linear portion is formed at a divided circumferential edge between the flanges.

In the motor mounting plate according to a fourth aspect, a rib is formed between the plate body and the flange.

In the motor mounting plate according to the first aspect, vibration in the first mode having the greatest amplitude and sound pressure can be reduced by a structure composed of a metallic plate without using an antivibration rubber and an effect in which resonance can be effectively inhibited by simple design and simple structure can be obtained.

In the motor mounting plate according to the second aspect, the vibration in the first mode can be more effectively reduced.

In the motor mounting plate according to the third aspect, the vibration in the first mode can be more effectively reduced. Furthermore, the vibration in the sixth mode can be reduced.

In the motor mounting plate according to the fourth aspect, the vibration in the first mode can be more effectively reduced.

DESCRIPTION OF PREFERRED EMBODIMENTS

Embodiments of the present invention are explained hereinafter.FIGS. 1A and 1Bare views showing basic structures similar to a motor mounting plate (hereinafter referred to simply as “mounting plate”) of the present invention. The mounting plate1is formed by drawing a metallic plate and is mainly composed of a disc-shaped plate body10, in which a circular hole11is formed at the radial center thereof. The plate body10has an annular peripheral wall12that is formed around a circumferential edge portion thereof and is perpendicularly bent toward the rear surface side, so that a recess13is formed at the rear surface side of the plate body10. Three or more flanges20(three flanges are formed in this embodiment) extended toward the radially outward direction are formed at an end edge of the peripheral wall12.

In the plate body10, plural screw holes14for mounting a motor by screwing are formed, and the motor is mounted to a front surface of the plate body10via the screw holes14. Three flanges20are formed at equally spaced locations in the circumferential direction and the portion between the flanges20is defined as a divided circumferential edge portion15. Each angle formed between the flanges20around the radial center is 120° and is the same as the others. A screw inserting through hole21is formed in each flange20. In the mounting plate1in which a motor is mounted to the plate body10via the screw holes14, the flanges20are tightened at a predetermined location in equipment such as a frame by screwing a screw or a bolt which is inserted into the screw inserting through holes21of the flanges20at a predetermined location thereof.

As shown inFIG. 2A, vibration in a first mode occurring in the mounting plate1shown inFIGS. 1A and 1Bexpands as a wave pattern. InFIGS. 2A to 8C, wavy lines drawn in the plate body10indicate strength of vibrational waves and the screw hole14is not shown therein. The vibration in the first mode expanding as a wave pattern has the greatest amplitude and the strongest sound pressure. Therefore, in the present invention, structures described in the following patterns are added to the mounting plate1having the basic structure shown inFIGS. 1A and 1B, so that a structure in which vibration in the first mode expanding as a wave pattern can be reduced is obtained.(A) One of the angles between the flanges20around the center is 140° to 180°.(B) In the above pattern (A), a linear portion is formed at the divided circumferential edge portion15between the flanges20.(C) In the above pattern (A) or (B), a rib is formed between the plate body10and the flanges20.

Mounting plates2,3and4of the above pattern (A) in which each angle between two flanges20disposed at a lower side of the mounting plate1having the basic structure shown inFIGS. 1A and 1Bset at 140°, 160° or 180° are shown inFIGS. 3A,3B and3C. In the mounting plate1having the basic structure in which the flanges20are disposed at equally spaced locations, the vibration expanding as a wave pattern occurs. However, in the mounting plates2,3and4shown inFIGS. 3A,3B and3C, the mode of the vibration is changed to a second mode, so that the vibration in the first mode can be reduced.

Next,FIG. 2Bshows a mounting plate1A having a structure in which linear portions16are formed at the divided circumferential edge portions15between the flanges20of the mounting plate1having the basic structure. Each linear portion16is parallel to a line passing through the screw inserting through holes21of the adjacent flanges20. In this mounting plate1A, the vibration in the first mode occurs as a wave pattern.

As shown inFIGS. 4A to 4C, in each mounting plate2,3and4inFIGS. 3A,3B and3C, the linear portion16is formed at the divided circumferential edge portion15between the flanges20, and mounting plates2A,3A and4A having the structure of the pattern (B) are obtained. That is, the linear portions16are formed at three divided circumferential edge portions15of the mounting plates2,3and4in which each angle between the flanges20is set at 140°, 160° or 180°. In the structure composed of the pattern (A) and the pattern (B), in which the linear portion16is formed at the divided circumferential edge portion15and each angle between the flanges20is set at 140°, 160° or 180°, the mode of the vibration changes to the second mode, so that the vibration in the first mode can be reduced.

Next, mounting plates2B,3B and4B shown inFIGS. 5A,5B and5C have structures of the pattern (C) in which the ribs30are formed between each plate body10and each flange20of the mounting plates2A,3A and4A shown inFIGS. 4A,4B and4C. In the mounting plates2B,3B and4B having the structure of the pattern (C), in which the linear portions16are formed at the divided circumferential edge portions15, each one of the angles between flanges20is set at 140°, 160° or 180° and the ribs30are formed between each plate body10and each flange20, the mode of the vibration changes to the second mode, so that the vibration in the first mode can be reduced.

FIG. 2Cshows a case in which vibration in the sixth mode occurs in the mounting plate1having the basic structure shown inFIGS. 1A and 1B. In this case, the vibration expanding as a wave pattern occurs. Therefore, as shown inFIG. 6, when the pattern (B) in which the linear portions16are formed at the divided circumferential edge portions15between the flanges20of the mounting plate1having the basic structure is added to this case, the sixth mode changes to a high-order mode, so that the vibration can be reduced.

FIGS. 7A to 7Cshow cases in which vibration in the sixth mode occurs in the plates2A,3A and4A shown inFIGS. 4A,4B and4C and the mode of each vibration changes to the high-order mode.FIGS. 8A to 8Cshow conditions in which the vibrations in the sixth mode occur in the plates2B,3B and4B shown inFIGS. 5A,5B and5C, and the mode of each vibration changes to the high-order mode.

Next, more specific examples of the mounting plate of the present invention are explained, again with reference toFIG. 9andFIGS. 10A and 10B.

FIG. 9shows a mounting plate having a structure in which the structures of the pattern (A) and the pattern (B) are combined. In the mounting plate5A, three flanges20are formed and the angle θ between two flanges20in the lower side is 140° to 180°.

In this case, a virtual circle passing through base end portions a, b and c as a bending portion of the flanges20from the peripheral wall12is defined as d. A virtual circle that is coaxial with the virtual circle d and has a diameter 1.05 times the diameter of the virtual circle d is defined as d1. A virtual circle that is coaxial with the virtual circle d and has a diameter 0.65 times the diameter of the virtual circle d is defined as d2. A regular hexagon of which each apex is on a circumference of the virtual circle d1is defined as e1and a regular hexagon of which each apex is on the virtual circle d2and each apex angle is the same as that of the regular hexagon e1is defined as e2. When vertical lines are drawn from a center “o” of the virtual circle d to each side of the regular hexagon e1, the linear portion16is positioned on the virtual lines from the center o between the hexagon e1and the hexagon e2. An angle between the point “a” and the point “b” around the center “o” is the angle between the flanges20and is 140° to 180°.

The mounting plate5B shown inFIGS. 10A and 10Bhas a structure of the pattern (C) in which a rib30is formed between the plate body10and the flange20of the mounting plate5A shown inFIG. 9. The rib30in this case has a rectangular shape in a plane view and is formed in a tapered shape having a rising slope toward the plate body10.

In this case, when the center of the virtual circle passing through the base end portions a, b and c is defined as “o”, the radius of the virtual circle is defined as “r” and the distance between the center “o”, the center of the screw inserting through hole21is defined as “rc”, the vibration in the first mode easily occurs if “rc” satisfies rc 1.15r, so that the vibration in the first mode is inhibited by a structure in which the ribs30are formed. In the structure, the width “wc” of the rib30is set at 0.25 times a diameter “dc” or more of the screw inserting through hole21of the flange20and the length “Lc” of the rib30is set at 1.14 times r or more (within the range of the length in which interference with respect to the screw for mounting the flange20can be avoided). The shape of the rib30in the plane view is not limited to the rectangular shape. Furthermore, the shape thereof may not be tapered but may have a uniform thickness.

In the present invention, dimensional setting satisfying the condition shown inFIG. 9orFIGS. 10A and 10Bis preferable.

FIG. 11Ashows another specific example of the mounting plate. In the mounting plate6B, the angle between two flanges20around the center is 140° and the plural screw holes14(in this case, four screw holes) are formed at the plate body10. The ribs30are formed between the plate body10and the flanges20. As shown inFIG. 11B, a flange42of a housing41of a motor40(such as an outer-rotor-type brushless motor) is tightened to the plate body10by screwing screws43passing through the flange42into the screw hole14, so that the motor40is mounted to the mounting plate6B. The mounting plate6B is mounted at a predetermined location by screwing using the screw inserting through hole21.

The present invention is not limited to the mounting plates having these explained structures. For example, as shown inFIG. 12A, the linear portion16may not be parallel to the line passing through the screw inserting through holes21of the adjacent flanges20, and as shown inFIG. 12B, plural (two) linear portions16may be formed at one divided circumferential edge portion15. The mounting plate may be produced not only by drawing a metallic plate, but also by bending a metallic plate, and may also be produced by die-casting.