JP2008079366A - Rectifier motor for electric tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rectifier motor for an electric tool which can reconcile the effective use of coil ends and the protection of the coil ends, and is high in performance and quality compared with a conventional technology. <P>SOLUTION: The rectifier motor 20 for the electric tool comprises a stator 21 which is a magnetic flux generation source, and a rotor 31 in which a core 33 having a plurality of slits 33a and a rectifier 34 are arranged at a shaft 32 which is rotatably held by a bearing 13 arranged at a housing of the electric tool 10, and which is constituted by connecting a coil 35 wound around the core 33 and the rectifier 34. At least either of a pair of the coil ends 35a, 35b protruding outward from axial both end faces of the core 33 is covered with a cup-shaped member 41. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a commutator motor for an electric tool, and more particularly to a technique for providing a high-performance and high-quality commutator motor for an electric tool as compared with the prior art.

  As a rotor of a commutator motor used for an electric tool, a rotor formed by pressing a core formed by stacking a plurality of magnetic steel plates into a shaft and winding a coil around the core is known. In this type of commutator motor for an electric tool, a pair of coil end portions inevitably protrude from both axial end surfaces of the core constituting the rotor. Various techniques for improving the motor performance by effectively using the coil end portion have been devised.

  For example, in Patent Documents 1 and 2 below, by adding an additional portion to the core, the opposing area between the core and the coil is maximized, and by using a coil end portion that has not been used conventionally, A motor structure in which motor loss is greatly reduced is disclosed. In particular, in the techniques disclosed in Patent Documents 1 and 2 below, installation of an additional portion for enlarging the core is realized by fastening with a pin.

  Patent Document 3 below discloses a technique for forming a core using a molded body of soft magnetic powder as another means for enlarging the core. According to the following Patent Document 3, since the degree of freedom of the core shape is increased by forming the core from a molded body of soft magnetic powder, the motor is more efficient than the case where the core is formed by stacking iron plates (steel plates). It is said that can be realized.

JP-A-2005-341628 JP-A-11-332140 JP 2001-86719 A

  However, in a commutator motor used for an electric tool that repeatedly generates large vibrations, such as a concrete hammer and a vibration drill, for example, a pin is used as in the techniques disclosed in Patent Documents 1 and 2 above. If the configuration in which the additional portion is fastened is employed, the additional portion may be detached and scattered. Therefore, the techniques disclosed in Patent Documents 1 and 2 are not suitable for safety as well as efficiency for use in electric tools.

  In the case of the core formed by the soft magnetic powder molded body described in Patent Document 3, the magnetic permeability is lower than that of the core formed by laminating the conventional magnetic steel plates, and the mechanical strength is low. It has the problem of being inferior. Therefore, in order to use the technique disclosed in Patent Document 3 for the rotor core, it is necessary to eliminate these problems.

  Further, in the case of a commutator motor using a permanent magnet for the stator, the end of the rotor in the direction of the rotation axis is always open and the coil end is exposed, so that metal processing is particularly performed. When used in an electric tool, magnetic scraps such as iron powder are attracted by permanent magnets, and there is a risk that the scraps may enter the motor and damage the coil. .

  The present invention has been made in view of the existence of the above-described problems, and the object thereof is to realize both effective use and protection of the coil end portion, and higher performance than the prior art. The object is to provide a high quality commutator motor for an electric tool.

  The present invention will be described below. In addition, in order to make an understanding of this invention easy, the reference number of an accompanying drawing is attached in parenthesis, However, This invention is not limited to the form of illustration.

  The commutator motor (20) for an electric tool according to the present invention is rotatably supported by a stator (21) that is a magnetic flux generation source and a bearing portion (13) provided in a housing of the electric tool (10). The shaft (32) is provided with a core (33) having a plurality of slits (33a) and a commutator (34), and the coil (35) wound around the core (33) is connected to the commutator (34). A rotor (31) connected to the coil (35), and the coil (35) is energized through a brush that contacts the commutator (34), thereby rotating the rotor (31). A commutator motor (20) for an electric tool configured to generate a rotational force, wherein at least one of a pair of coil end portions (35a, 35b) protruding from both axial end surfaces of the core (33), Cup-shaped member ( Characterized by being configured to cover by 1).

  In the commutator motor (20) for an electric tool according to the present invention, the cup-shaped member (41) is made of a magnetic material configured in a cylindrical shape so as to cover the circumferential direction of the coil end portions (35a, 35b). A cylindrical portion (41a) and a bottom portion (41b) made of a non-magnetic material installed on one end side of the cylindrical portion (41a) so as to cover the axial end face side of the coil end portion (35a, 35b). It can be configured.

  In the commutator motor (20) for an electric tool according to the present invention, the bottom (41b) can be press-fitted and fixed to the shaft (32).

  Furthermore, in the commutator motor (20) for an electric tool according to the present invention, the cylindrical portion (41a) includes a convex shape (41c) on the side in contact with the axial end surface of the core (33), and the convex portion The shape (41c) can be configured to fit into the plurality of slits (33a) of the core (33).

  According to the present invention, both effective use and protection of the coil end portion can be realized, and a high-performance and high-quality commutator motor for an electric tool can be provided as compared with the prior art.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments for carrying out the invention will be described with reference to the drawings. The following embodiments do not limit the invention according to each claim, and all combinations of features described in the embodiments are not necessarily essential to the solution means of the invention. .

  FIG. 1 is a partial vertical cross-sectional schematic view showing an application example of the electric tool commutator motor 20 according to the present embodiment. The commutator motor 20 for an electric tool according to the present embodiment is used for an electric tool 10 such as an impact driver having a substantially L-shaped outer shape as illustrated in FIG. A commutator motor 20 for an electric tool illustrated in FIG. 1 is arranged at an upper rear position of an approximately L-shaped electric tool 10 and is supplied with electric power from a battery pack (not shown) arranged at a lower position of the electric tool serving as a grip portion 11. Is provided, and plays a role of transmitting rotational power to the impact mechanism portion 12 disposed at the upper front position of the electric tool serving as the action portion.

  The specific configuration of the commutator motor 20 for an electric tool according to the present embodiment arranged as described above will be described in more detail with reference to FIGS. In addition, FIG. 2 is a partial longitudinal cross-sectional side view which shows the rotor which comprises the commutator motor for electric tools which concerns on this embodiment. FIG. 3 is an exploded perspective view of a rotor constituting the commutator motor for an electric tool according to the present embodiment.

  In the commutator motor 20 for an electric tool according to the present embodiment, a permanent magnet is employed for the stator 21 and exhibits a function as a magnetic flux generation source. On the other hand, the rotor 31 includes a shaft 32 rotatably supported by a bearing portion 13 provided in the housing of the electric power tool 10, a core 33 including a plurality of slits 33a installed on the shaft 32, and a core Similarly to 33, a commutator 34 installed on the shaft 32 and a coil 35 wound around the core 33 are provided. The coil 35 is configured to be connected to a commutator 34. When the coil 35 is energized through a brush (not shown) that contacts the commutator 34, a rotational force for rotating the rotor 31 is generated. It is like that.

  In addition, the rotor 31 of the electric tool commutator motor 20 according to the present embodiment uses the gap around the coil end portion 35a protruding from the axial rear end surface of the core 33, and the core 33 on the shaft 32. A cooling fan 36 is attached at a position between the commutator 34. With the rotation of the rotor 31, the cooling fan 36 rotates and a flow of cooling air is generated in the housing, thereby removing heat generated from the commutator motor 20 for the electric tool and maintaining the motor performance. Yes.

  Further, the rotor 31 of the electric tool commutator motor 20 according to the present embodiment is provided with a cup-shaped member 41 so as to cover the coil end portion 35 b protruding from the axial front end surface of the core 33.

  The configuration of the cup-shaped member 41 will be described with reference to FIG. Here, FIG. 4 is a figure for demonstrating the structure of the cup-shaped member which concerns on this embodiment, especially (a) in a figure is a rear surface external appearance, (b) in a figure is a longitudinal cross-section side surface, The middle (c) shows the front appearance.

  That is, the cup-shaped member 41 according to the present embodiment covers the cylindrical portion 41a made of a magnetic material configured in a cylindrical shape so as to cover the circumferential direction of the coil end portion 35b, and the axial end surface side of the coil end portion 35b. Thus, it is comprised from the bottom part 41b which consists of a nonmagnetic material installed in the one end side of the cylindrical part 41a.

  An opening for connecting to the shaft 32 is provided at the center position of the bottom portion 41b. In the rotor 31 illustrated in this embodiment, the cup-shaped member 41 is formed by press-fitting the shaft 32 and the bottom portion 41b. Secure fixing is realized.

  Further, a plurality of convex shapes 41c are formed on the end surface side opposite to the bottom 41b installation side of the cylindrical portion 41a. That is, the cylindrical portion 41 a is provided with a convex shape 41 c on the side in contact with the axial end surface of the core 33, and this convex shape 41 c is fitted to a plurality of slits 33 a of the core 33. It is provided in the position to do.

  In addition, about the magnetic material which comprises the cylindrical part 41a, you may comprise by the sintered compact of magnetic powder, and you may use what formed the material similar to the electromagnetic steel plate which comprises the core 33 in the cylindrical shape. . Moreover, about the nonmagnetic material which comprises the bottom part 41b, nonmagnetic materials, such as resin, the nonferrous metal which does not have magnetism, such as aluminum and aluminum alloy, are employable.

  By applying the cup-shaped member 41 described above, the commutator motor 20 for an electric tool according to the present embodiment can exhibit various suitable functions and effects. This effect will be described with reference to FIG. FIG. 5 is a schematic diagram for explaining the operational effects of the commutator motor for an electric tool according to the present embodiment.

  First, in the rotor 31 of the commutator motor 20 for an electric tool according to the present embodiment, the cup-shaped member 41 is installed in the space around the coil end portion 35b, which has conventionally been a useless space. Since the cup-shaped member 41 is configured such that the cylindrical portion 41a made of a magnetic material is disposed at a position in the circumferential direction of the coil end portion 35b, the area facing the stator 21 made of a permanent magnet is increased. be able to. Further, the axial end surface side of the cup-shaped member 41, which is not related to the increase in the facing area, is constituted by the bottom 41 b made of a nonmagnetic material, so that the magnetic flux from the stator 21 is efficiently brought to the rotor 31 side. (Refer to the broken line with an arrow in FIG. 5). By the operation of the cup-shaped member 41 according to the present embodiment as described above, an area where the magnetic flux generated by the stator 21 can be enjoyed can be increased, and an effect of increasing the amount of magnetic flux for rotational driving can be obtained. it can. With such an effect, it is possible to provide a high-performance motor.

  Further, in the commutator motor 20 for an electric tool according to the above-described embodiment, since a permanent magnet is used for the stator 21, when the magnetic material such as metal is processed by the electric tool 10, this magnetic tool is used. There is a possibility that the processing scraps having a diameter will be attracted by the strong magnetic force of the permanent magnet. However, the action of the cup-shaped member 41 according to the present embodiment can protect the coil 35 (particularly, the coil end portion 35b protruding from the core 33) from such processing waste, and thus the electric motor according to the present embodiment. According to the tool commutator motor 20, it is possible to provide an effect that high-quality motor performance can be provided in any work environment.

  Furthermore, since the cup-shaped member 41 according to the present embodiment employs a configuration in which the bottom 41b is press-fitted and fixed to the shaft 32, the concentricity between the rotor 31 that is a rotating body and the cup-shaped member 41 is adopted. As a result, it is possible to provide a high-quality motor.

  Furthermore, in the cup-shaped member 41 according to the present embodiment, the convex portion shape 41 c formed in the cylindrical portion 41 a is configured to fit into the plurality of slits 33 a included in the core 33. This embodiment employs such a configuration for the following reason. That is, in the conventional commutator motor, the inductance may change steeply due to the effect of the slit provided on the rotor, and this phenomenon generates cogging torque, which causes noise and vibration. Therefore, in the commutator motor 20 for an electric tool according to the present embodiment, the convex shape 41 c formed in the cylindrical portion 41 a fills the plurality of slits 33 a of the core 33. By adopting such a configuration, the commutator motor 20 for an electric tool according to the present embodiment can prevent a steep change in inductance, thereby preventing the occurrence of cogging torque. Moreover, since the installation state of the cup-shaped member 41 is stabilized by the fitting of the convex shape 41c and the slit 33a, the reliability as a motor can be improved. Since the present invention can exert the above-described effects, it is possible to provide a high-performance and high-quality motor.

  As mentioned above, although preferred embodiment of this invention was described, the technical scope of this invention is not limited to the range as described in the said embodiment. Various modifications or improvements can be added to the embodiment.

  For example, one cup-shaped member 41 according to the present embodiment is installed so as to cover only the coil end portion 35b on the front side of the electric power tool 10, but only the coil end portion 35a on the commutator 34 side is covered. One may be installed, or two may be installed so as to cover both of the two coil end portions 35a and 35b.

  Moreover, about the shape of the cup-shaped member 41 which concerns on this embodiment, it does not restrict to what was illustrated, It changes suitably in the range which can exhibit the effect of this invention according to the shape of the electric tool 10, a motor shape, etc. It is possible.

  Furthermore, in this embodiment, a permanent magnet is used for the stator 21 of the motor. However, the present invention can also be applied to a universal motor using an electromagnet for the stator.

  It is apparent from the description of the scope of claims that embodiments to which the above modifications or improvements are added can also be included in the technical scope of the present invention.

It is a partial longitudinal cross-sectional schematic diagram which shows the application example of the commutator motor for electric tools which concerns on this embodiment. It is a partial longitudinal cross-sectional side view which shows the rotor which comprises the commutator motor for electric tools which concerns on this embodiment. It is a perspective component expansion view of the rotor which comprises the commutator motor for electric tools which concerns on this embodiment. It is a figure for demonstrating the structure of the cup-shaped member which concerns on this embodiment, especially (a) in a figure is a rear surface external appearance, (b) is a longitudinal cross-section side surface, (c) is a front external appearance in the figure. Is shown. It is the schematic for demonstrating the effect of the commutator motor for electric tools which concerns on this embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Electric tool, 11 Holding part, 12 Impact mechanism part, 13 Bearing part, 20 Commutator motor for electric tools, 21 Stator, 31 Rotor, 32 Shaft, 33 Core, 33a Slit, 34 Commutator, 35 Coil, 35a , 35b Coil end portion, 36 cooling fan, 41 cup-shaped member, 41a cylindrical portion, 41b bottom portion, 41c convex shape.

Claims (4)

A stator which is a magnetic flux generation source,
A shaft provided with a plurality of slits and a commutator are installed on a shaft rotatably supported by a bearing portion provided in a housing of the electric power tool, and a coil wound around the core is connected to the commutator. A rotor configured;
In the commutator motor for an electric tool configured to generate a rotational force for rotating the rotor by energizing the coil through a brush in contact with the commutator,
A commutator motor for an electric tool, wherein at least one of a pair of coil end portions protruding from both axial end surfaces of the core is covered with a cup-shaped member. The commutator motor for an electric tool according to claim 1,
The cup-shaped member is
A cylindrical portion made of a magnetic material configured in a cylindrical shape so as to cover the circumferential direction of the coil end portion;
A bottom portion made of a non-magnetic material installed on one end side of the cylindrical portion so as to cover the axial end face side of the coil end portion;
The commutator motor for electric tools characterized by being comprised from these. The commutator motor for an electric tool according to claim 2,
A commutator motor for an electric tool, wherein the bottom portion is press-fitted and fixed to the shaft. In the commutator motor for electric tools according to claim 2 or 3,
The cylindrical portion has a convex shape on the side in contact with the axial end surface of the core,
A commutator motor for an electric tool, wherein the convex shape is configured to fit into a plurality of slits of the core.

Images