JP2009056564A - Power tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power tool having a fan of low noise and high strength by reducing a separation vortex to reduce noise and by restraining the fan from being deformed by centrifugal force. <P>SOLUTION: The power tool has a motor, a fan body provided in the motor, and blades provided in the fan body, wherein an inlet through which air flows into the fan body has a portion where the blade extends in a reverse direction to the rotating direction of the blades from the radial inside toward the outside and a blade angle defined by the blade and a line segment extending from the center of the fan body to the blade is the largest. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electric tool provided with a centrifugal fan.

Conventionally, there is a high demand for miniaturization, high output, and low noise of electric tools, and accordingly, there is an increasing need for development of a motor cooling fan and a fan periphery that is small in size and has high cooling capacity and low noise. As an example of the invention of such a motor cooling fan, there is an example in which the blade shape of a centrifugal fan is optimized, for example, as disclosed in JP-A-10-153194, and the air volume is increased and the noise is reduced. The grinding tool which is an example of the mounted electric tool is shown. The drive shaft 12 is rotated by the rotation of the rotor 11 of the electric motor, the rotation is transmitted to the output shaft 18 by the engagement of the pinion 16 attached to the drive shaft 12 and the gear 17, and the grinding member 19 attached to the output shaft 18. Grinding work is performed by rotating. Reference numeral 15 is a gear cover in which a pinion 16, a gear 17 and the like are accommodated, 14 is a motor housing, and 20 is a switch.

  The flow of cooling air for cooling the electric motor and the like will be described with arrows in FIG. Due to the rotation of the centrifugal fan 13 fixed to the drive shaft 12, cooling air is introduced like a <b> 1 and a <b> 2 from an intake port (not shown) of the tail cover 21 that houses a switch control unit (not shown). Thereafter, the air passes through the air passage b formed by the motor housing 14 and the rotor 11, the cooling air flows out in the centrifugal direction from the inner diameter portion of the centrifugal fan 13, and flows out through the discharge port d provided in the gear cover 15. .

  A conventional cooling fan will be described with reference to FIGS. FIG. 5 is a main part view of the centrifugal fan 13, FIG. 6 is a main part sectional view of the centrifugal fan 13, and FIG. 7 is a perspective view of the centrifugal fan 13. The disk-shaped fan base 1 is provided at the center of the fan base 1, a plurality of blades 2 extending from a predetermined radial position of the fan base 1 to the outer periphery and formed at a predetermined pitch along the circumferential direction of the fan base 1. The hub 3 and the like attached to a drive shaft (not shown) are integrally formed. When the centrifugal fan 13 is rotated, kinetic energy is given to the air by centrifugal action, and the air path formed by the fan base 1, the blade 2, and the fan guide 4 from the inlet portion C that is the inner periphery of the blade 2 is indicated by the arrow A. In this way, the wind passes and is discharged radially outward from the outlet portion which is the outer peripheral portion of the blade 2.

  The blade 2 has a first region 2a1 and a second region 2b1 as shown in FIGS. The first region 2a1 is a region in which the height of the blade 2 is increased from the inner side in the radial direction of the centrifugal fan 13 toward the outer blade tip 43. The first region 2a1 includes an inner diameter inclined portion 44 as shown in FIG. The second region 2b1 is a region heading from the first region 2a1 toward the outer peripheral end 41 that is further outside. As shown in FIG. 6, the second region 2 b 1 has an outer peripheral inclined portion 42.

  Fan noise during fan rotation generally contributes to the flow speed, and fluid noise is said to be proportional to the sixth power of the flow speed. The noise is reduced by making it slower than the speed.

  As shown in FIG. 5, the cooling fan 13 is provided with angles (D1, D2) opposite to the rotation direction with respect to the direction in which the blades 2 extend from the predetermined radial position of the fan base 1 to the outer periphery.

  The angle D2 is an angle formed between the blade 2 and a line segment extending from the center of the centrifugal fan 13 to the blade in the first region 2a1. Hereinafter, an angle formed by the blade 2 and a line segment extending from the center of the centrifugal fan 13 to the blade will be described as a blade angle. The angle D1 is a blade angle in the second region.

  As shown in FIG. 5, the blade angles D1 and D2 are gradually reduced from the outer diameter side toward the inner diameter side. As a result, the inner blade angle D2 becomes smaller, so that the strength against the centrifugal force when the fan is rotating is strong, and it is possible to suppress the blade from being deformed and to stabilize the fan performance. In particular, since the motor used in the electric tool rotates at a high speed, strength against centrifugal force is required.

JP-A-10-153194

  However, since the inner diameter blade angle D2 is small, the air path formed by the fan base 1, the blade 2, and the fan guide 4 from the inlet portion C that is the inner periphery of the blade 2, as shown in FIG. As shown in FIG. 5, a separation flow is generated in the inlet portion C when passing through and being discharged radially outward from the outlet portion that is the outer peripheral portion of the blade 2. B will occur. This peeling vortex B caused noise and became a problem.

  Reducing the separation vortex B can be solved by increasing the inner blade angle D2, but the strength against centrifugal force during rotation of the fan decreases, and the fan characteristics change due to blade deformation. Problem occurs.

  An object of the present invention is to provide an electric tool including a low noise and high strength fan by reducing the separation vortex and reducing noise and suppressing the fan from being deformed by centrifugal force. is there.

  The object is to provide a power tool having an electric motor, a fan main body provided on the electric motor, and a blade provided on the fan main body, wherein the blade is provided in a radial direction at an inlet through which air flows into the fan main body. Achieved by the fact that there is a portion where the blade angle between the blade and the line extending from the center of the fan body to the blade is maximized as it extends from the inside to the outside in the direction opposite to the rotation direction of the blade. Is done.

  Further, this is achieved by decreasing the blade angle from the portion where the blade angle becomes maximum toward the outside in the radial direction.

  In addition, the blade has a first region where the height of the blade increases as it goes from the inside in the radial direction of the fan body to the outside, and a second region that goes further outward from the first region, In the first region, the blade angle is achieved by having an inflection point that is small on the inner side in the radial direction of the fan body and larger on the outer side.

  Further, this is achieved when the blade angle is 0 degree in the first region.

  In addition, this is achieved by providing an R portion at a joint portion between the first region and a base portion provided on the fan body and supporting the blades.

  Further, in an electric tool having an electric motor, a fan main body provided in the electric motor, and blades provided in the fan main body, the blades are arranged in a direction from the inner side to the outer side in the radial direction of the fan main body. A first region that increases in height, and a second region that extends further outward from the first region, the first region extending from the center of the blade and the fan body to the blade. Is achieved by having an inflection point that is small on the inside in the radial direction of the fan body and large on the outside.

  According to the first aspect of the present invention, it is possible to prevent the separation flow from being generated at the inlet where the air flows into the fan main body, and to prevent the separation vortex from being generated in the air passage. Therefore, it is possible to provide a low noise electric tool including a fan that can prevent generation of noise.

  According to invention of Claim 2 and 3, a blade | wing can be suppressed from a deformation | transformation by centrifugal force. Therefore, it is possible to provide a power tool having a high durability and having excellent durability.

  According to the fourth aspect of the present invention, the blade can be most effectively suppressed from deformation due to centrifugal force. Therefore, it is possible to provide a low noise electric tool including a fan that can prevent generation of noise.

  According to the fifth aspect of the present invention, stress concentration can be prevented at the blade and the base portion supporting the blade. Therefore, the blade can be suppressed from being deformed by centrifugal force. Therefore, it is possible to provide a power tool having a high durability and having excellent durability.

  According to invention of Claim 6, a blade | wing can be suppressed from a deformation | transformation by centrifugal force. Therefore, it is possible to provide a power tool having a high durability and having excellent durability.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 4 shows a grinding tool as an example of an electric tool equipped with a motor cooling fan. The embodiment of the present invention is basically the same as the structure described in the section of the background art except for the centrifugal fan 13 and the surrounding structure, so the background of the basic structure of the embodiment of the present invention is as follows. It demonstrates using FIG. 4 similarly to a technique.

  The drive shaft 12 is rotated by the rotation of the rotor 11 of the electric motor, the rotation is transmitted to the output shaft 18 by the engagement of the pinion 16 attached to the drive shaft 12 and the gear 17, and the grinding member 19 attached to the output shaft 18. Grinding work is performed by rotating. Reference numeral 15 is a gear cover in which a pinion 16, a gear 17 and the like are housed, 14 is a motor housing, and 20 is a switch.

  The flow of cooling air for cooling the electric motor and the like will be described with arrows in FIG. Due to the rotation of the centrifugal fan 13 fixed to the drive shaft 12, cooling air is introduced like a <b> 1 and a <b> 2 from an intake port (not shown) of the tail cover 21 that houses a switch control unit (not shown). Thereafter, the air passes through the air passage b formed by the motor housing 14 and the rotor 11, the cooling air flows in the centrifugal direction from the inner diameter portion of the centrifugal fan 13, and flows out from the discharge port d provided in the gear cover 15. .

  A cooling fan according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a main part view of the centrifugal fan 13, FIG. 2 is a main part sectional view of the centrifugal fan 13, and FIG. 3 is a perspective view of the centrifugal fan 13.

The disk-shaped fan base 1 is provided at the center of the fan base 1, a plurality of blades 2 extending from a predetermined radial position of the fan base 1 to the outer periphery and formed at a predetermined pitch along the circumferential direction of the fan base 1. The hub 3 and the like attached to a drive shaft (not shown) are integrally formed. When the centrifugal fan 13 is rotated, kinetic energy is given to the air by centrifugal action, and the air path formed by the fan base 1, the blade 2, and the fan guide 4 from the inlet portion C that is the inner periphery of the blade 2 is indicated by the arrow A. And is discharged radially outward from the outlet portion which is the outer peripheral portion of the blade 2.
As shown in FIGS. 1 and 2, the blade 2 has first regions 2a and 2b and a second region 2c. The first regions 2 a and 2 b are regions 2 a and 2 b in which the height of the blade 2 increases from the inner side in the radial direction of the centrifugal fan 13 toward the outer blade top 43. The first regions 2a and 2b have an inner diameter inclined portion 44 as shown in FIG. The second region 2c is a region 2c that goes from the first region 2a, 2b to the outer peripheral end 41 that is further outside. As shown in FIG. 6, the second region 2 c has an outer peripheral inclined portion 42.

  Fan noise during fan rotation generally contributes to the flow speed, and fluid noise is said to be proportional to the sixth power of the flow speed. The noise is reduced by making it slower than the speed.

  As shown in FIG. 1, the centrifugal fan according to an embodiment of the present invention has angles (D1, D2, D3) opposite to the rotation direction with respect to the direction in which the blades 2 extend from the predetermined radial position of the fan body 1 to the outer periphery. Provided.

  The angle D3 is a blade angle in the first regions 2a and 2b. The angle D1 is a blade angle in the second region 2c. The angle D2 is a blade angle at the boundary between the first regions 2a and 2b and the second region 2c.

  Further, in the blade angle, the angle gradually increases from the blade angle D1 to the blade angle D2, the blade is bent at the inner diameter inclined portion 44 from the blade vertex 43 to the inner diameter side, and the blade angle D3 is smaller than the blade angle D2. Is set.

  As shown in FIGS. 1 and 2, there is an inflection point 2d where the blade angle is small on the inner side in the radial direction of the fan 13 and larger on the outer side on the boundary line between 2a and 2b in the first regions 2a and 2b. To do.

  In order to suppress the blade 2 from being deformed by centrifugal force, it is effective that the blade angle D3 is small. In the present invention, in order to suppress the blade 2 from being deformed by centrifugal force, the blade angle D1 and the blade angle D3 are reduced. It is set.

  On the other hand, in the inner diameter inclined portion 44 that becomes the inlet portion C of the fan air passage, a large blade angle equal to or greater than the blade angle D2 can be set. B can be suppressed, and noise reduction can be realized.

  Further, in order to suppress the blade 2 from being deformed by centrifugal force, the blade angle D3 is the parameter with the highest contribution. Therefore, the blade angle D3 is the angle at which deformation due to the centrifugal force is most suppressed, that is, radial 0 It is possible to suppress the blades from being deformed by centrifugal force most by setting the degree.

  In addition, in order to suppress the blade | wing 2 from a deformation | transformation by centrifugal force, it can also be solved by providing a rib in 2nd area | region 2b, 2c.

  Further, as shown in FIG. 2, by providing the R portion 45 at the joint between the first regions 2a and 2b of the blade 2 and the fan base 1 that is provided in the centrifugal fan 13 and supports the blade 2, the blade can be efficiently used. Can be suppressed from deformation due to centrifugal force.

  As described above, according to the present invention, an electric tool provided with a low-noise and high-strength fan can be provided while reducing noise by reducing separation vortices and suppressing deformation due to centrifugal force. It becomes possible to do.

  Further, as shown in FIG. 2, there is a portion where the blade angle becomes maximum at the entrance C where the air flows into the centrifugal fan 13. Therefore, in the inner diameter portion inclined portion 44 serving as the inlet portion C of the fan air passage, a large blade angle equal to or greater than the blade angle D2 can be set. Therefore, the air flow does not change abruptly before and after the inlet C where the air flows into the centrifugal fan 13. Therefore, it is possible to suppress the separation vortex B, and it is possible to realize a reduction in noise.

  In addition, although demonstrated using the grinding tool as an electric tool which concerns on embodiment of this invention, it is not limited to a cutting tool, It is applicable also to a cutting tool, an electric drill, a screwing machine, etc.

The principal part figure which shows the centrifugal fan which concerns on one Embodiment of this invention. The principal part sectional view showing the centrifugal fan concerning one embodiment of the present invention. The perspective view which shows the centrifugal fan which concerns on one Embodiment of this invention. Sectional drawing of the electric tool to which the centrifugal fan which concerns on one Embodiment of this invention is applied. The principal part figure which shows one Embodiment of the conventional centrifugal fan. Sectional drawing which shows the principal part which shows one Embodiment of the conventional centrifugal fan. The perspective view which shows one Embodiment of the conventional centrifugal fan.

Explanation of symbols

Reference numeral 1 is a base, 2 is a blade, 3 is a hub, 4 is a fan guide, 41 is an outer peripheral end, 42 is an outer peripheral inclined portion, 43 is a blade apex, 44 is an inner diameter inclined portion, D1, D2, and D3 are blade angles , D3 is the blade angle at the blade inner end.

Claims (6)

An electric motor,
A fan body provided in the electric motor;
Blades provided on the fan body,
In an electric tool having
A line extending from the center of the blade and the fan body to the blade at the entrance into which air flows into the fan body, the blade extending in the direction opposite to the rotation direction of the blade as it goes from the inner side to the outer side in the radial direction. An electric tool characterized in that there is a portion where the blade angle with the minute is maximum. The power tool according to claim 1, wherein the blade angle decreases from the portion where the blade angle becomes maximum toward the outside in the radial direction.   The blade has a first region in which the height of the blade increases from the inside to the outside in the radial direction of the fan body, and a second region further outward from the first region, The power tool according to claim 1, wherein the blade angle in the region 1 has an inflection point that is small on the inner side in the radial direction of the fan body and larger on the outer side.   The power tool according to claim 3, wherein the blade angle is 0 degrees in the first region.   4. The electric power tool according to claim 3, wherein an R portion is provided at a joint portion between the first region and a base portion provided in the fan body and supporting the blades. An electric motor,
A fan body provided in the electric motor;
Blades provided on the fan body,
In an electric tool having
The blade has a first region in which the height of the blade increases from the inside to the outside in the radial direction of the fan body, and a second region further outward from the first region, The region 1 has an inflection point in which a blade angle formed by the blade and a line segment extending from the center of the fan body to the blade has a small inward in the radial direction of the fan main body and a large in the outer side. tool.

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