Power tool having a hammer mechanism and a cooling fan

Patent metadata

Field	Value
Publication number	US-11623333-B2
Application number	US-202117217233-A
Country	US
Kind code	B2
Filing date	Mar 30, 2021
Priority date	Mar 31, 2020
Publication date	Apr 11, 2023
Grant date	Apr 11, 2023

Abstract

A power tool includes a hammer mechanism, a brushless motor and a cooling fan. The brushless motor includes a rotary member having a motor shaft operably coupled to the hammer mechanism for linearly driving a tool accessory. The cooling fan has a first blade part and is configured to be rotated by the rotary member. The cooling fan includes a polymer portion, which forms at least a portion of the first blade part, and a metal portion disposed in or on the polymer portion. When viewed in a direction parallel to a rotational axis of the cooling fan, the metal member at least partially overlaps the first blade part in a radial direction of the cooling fan.

First claim

What is claimed is:

1. A power tool comprising:
a hammer mechanism;
a brushless motor that includes a rotary member having a rotor and a motor shaft, the brushless motor being is configured such that the rotary member generates a rotational driving force for use in driving a tool accessory; and
a cooling fan operably coupled to the rotary member and configured to be rotated thereby, the cooling fan having a first blade part,
wherein:
the cooling fan includes a resin member and a metal member,
the resin member forms at least a portion of the first blade part,
when viewed in a direction parallel to a rotational axis of the cooling fan, the metal member at least partially overlaps the first blade part in a radial direction of the cooling fan, and
the metal member has a mass that is 15% or more of a total combined mass of the rotary member and the resin member of the cooling fan.

2. The power tool as defined in claim 1 , wherein the metal member is at least partially disposed in a radially outer half of the cooling fan.

3. The power tool as defined in claim 1 , wherein:
the cooling fan is fixedly connected to the motor shaft,
a connection part of the cooling fan that is fixedly connected with the motor shaft is formed by a portion of the metal member, and
the motor shaft is press-fit in an insertion hole defined by the portion of the metal member.

4. The power tool as defined in claim 1 , wherein the cooling fan has a diameter of 80 mm or more.

5. The power tool as defined in claim 1 , wherein:
the first blade part is disposed on a first side of the cooling fan in the direction parallel to the rotational axis of the cooling fan; and
the metal member is disposed on a second side of the cooling fan that is opposite to the first side in the direction parallel to the rotational axis direction.

6. The power tool as defined in claim 1 , wherein:
the cooling fan has a second blade part,
the first blade part and the second blade part are respectively disposed on opposite sides of the cooling fan in the direction parallel to the rotational axis of the cooling fan, and
the metal member is interposed between the first blade part and the second blade part in the direction parallel to the rotational axis.

7. The power tool as defined in claim 1 , wherein a rotation part that includes the rotary member of the brushless motor and the cooling fan has a moment of inertia of 1.6×10 −4 kg·m 2 or more.

8. The power tool as defined in claim 1 , wherein the power tool is configured to output an impact energy of 9.0 J or more.

9. The power tool as defined in claim 1 , wherein:
the power tool is configured to perform a processing operation on a workpiece by linearly driving the tool accessory, and
a direction in which the tool accessory is linearly driven crosses or is skewed with respect to a direction of a rotational axis of the brushless motor.

10. The power tool as defined in claim 1 , further comprising:
a battery mounting part configured such that a rechargeable battery is removably mounted thereon,
wherein the brushless motor is energized using power that is supplied from the battery mounted on the battery mounting part.

11. The power tool as defined in claim 1 , wherein the mass of the metal member of the cooling fan is such that a load current of the power tool is minimized when the power tool is driven while a constant pressing load by the tool accessory is applied to a workpiece.

12. The power tool as defined in claim 1 , wherein a rotation part that includes the rotary member of the brushless motor and the cooling fan has a moment of inertia such that a load current of the power tool is minimized when the power tool is driven while a constant pressing load is applied by the tool accessory to a workpiece.

13. The power tool as defined in claim 1 , wherein:
the metal member is ring shaped when viewed in the direction parallel to the rotational axis of the cooling fan,
an inner contour of the ring-shaped metal member of the cooling fan is located radially inward of an inner peripheral edge of the first blade part in a radial direction of the cooling fan, and
an outer contour of the ring-like metal member of the cooling fan is located radially inward of an outer peripheral edge of the first blade part in the radial direction of the cooling fan.

14. The power tool as defined in claim 1 , wherein the metal member of the cooling fan is integrally molded with or on the resin member.

15. A power tool comprising:
a hammer mechanism;
a brushless motor comprising a motor shaft that is rotatable around a rotational axis and is operably coupled to the hammer mechanism; and
a cooling fan operably coupled to the motor shaft and configured to be rotated thereby, the cooling fan having blades,
wherein:
the cooling fan comprises a polymer portion that forms at least a portion of the blades,
a metal weight is disposed on or is at least partially embedded in the polymer portion,
when viewed in a direction parallel to a rotational axis of the cooling fan, the metal weight at least partially overlaps the blades in a radial direction of the cooling fan that is perpendicular to the rotational axis, and
the metal weight has a mass that is 15% or more of a total combined mass of the motor shaft, a rotor fixedly connected to the motor shaft and the polymer portion of the cooling fan.

16. The power tool according to claim 15 , wherein:
the metal weight has an inner circular peripheral edge and an outer circular peripheral edge,
the inner circular peripheral edge defines a through hole,
a radius of the cooling fan in the radial direction is defined between the rotational axis and an outer peripheral edge of the cooling fan, and
the outer circular peripheral edge of the metal weight is disposed between one-half of the radius of cooling fan in the radial direction and the outer peripheral edge of the cooling fan.

17. The power tool according to claim 16 , wherein:
the inner circular peripheral edge of the metal weight is disposed radially inward of radially inward edges of the blades in the radial direction, and
the motor shaft is press-fit in the through hole defined by the inner circular peripheral edge of the metal weight.

18. The power tool as defined in claim 17 , wherein:
the metal weight is a continuous, annular piece of metal or a plurality of discrete pieces of metal that extend(s) along a circle around the rotational axis,
the continuous piece of metal or each of the discrete pieces of metal has a width in the radial direction and a thickness in the direction of the rotational axis such that the width is at least two times the thickness,
at least one through hole is defined in the continuous piece of metal or in each of the discrete pieces of metal between the inner circular peripheral edge and the outer circular peripheral edge, and
the polymer portion fills the at least one through hole.

Assignees

• Makita Corp

Inventors

• Furusawa Masanori
• Takeuchi Hajime
• Inoue Yoji

Classifications

• B25D17/20 Primary

  Devices for cleaning or cooling tool or work · CPC title

• B25D2217/0061

  related to cooling · CPC title

• B25D2250/095

  Electric motors · CPC title

• B25D2211/068

  Crank-actuated impulse-driving mechanisms · CPC title

• B25D17/06

  Hammer pistons; Anvils {; Guide-sleeves for pistons} · CPC title