US-12617028-B2 - Power tool and control module therefor

US12617028B2US 12617028 B2US12617028 B2US 12617028B2US-12617028-B2

Abstract

A control module ( 10 ) for a power tool includes a box-shaped case ( 60 ), one side of which is open, and a circuit board ( 50 ) housed in the case. A microcomputer ( 51 ) and FETs ( 52 ) configured to control a brushless motor ( 1 c) of the power tool are mounted on the circuit board. Movable switches ( 30 ) are mechanically linked to movement of a trigger ( 20 ) and are electrically connected to the circuit board. A cover ( 70 ) partially covers the opening of the case such that a portion of the circuit board and the movable switches are covered. Bonded parts ( 14 ) weld or otherwise materially bond the cover and the case to form an enclosed space ( 13 ), which encloses the movable switches.

Inventors

Mario Revelli

Assignees

MAKITA CORPORATION

Dates

Publication Date: 20260505
Application Date: 20250110
Priority Date: 20240214

Claims (20)

1 . A control module for a power tool, including: a box-shaped case, one side of which is open; a circuit board housed in the case; a microcomputer and field effect transistors (FETs), which are mounted on the circuit board and are configured to control a brushless motor of the power tool; a manipulatable member, which is movable relative to the case; one or more movable switches electrically connected to the circuit board and mechanically linked to movement of the manipulatable member; a cover, which partially overlays the case opening so as to cover a portion of the circuit board and so as to cover the movable switch(es); and bonded parts that form an enclosed space, which encloses the movable switch(es), by welding or otherwise materially bonding the cover to the case; wherein: the case has a case bottom wall and case peripheral walls extending perpendicular from peripheral edges of the case bottom wall; the cover has a cover bottom wall and cover peripheral walls extending perpendicular from peripheral edges of the cover bottom wall; the bonded parts weld or otherwise materially bond, to each other, case facing-surfaces of the case peripheral wall and cover facing-surfaces of the cover peripheral wall, which face each other in their directions of extension; the cover has guide pieces, which extend toward the case beyond the cover facing-surfaces of the cover peripheral walls and extend so as to pass between the case peripheral walls and side surfaces of the circuit board, the guide pieces fitting between the circuit board and the case peripheral walls; and the bonded parts weld or otherwise materially bond extending ends of the guide pieces to the case.
2 . The control module for a power tool according to claim 1 , wherein: the microcomputer and the FETs are provided on the circuit board at positions outside of the enclosed space.
3 . The control module for a power tool according to claim 1 , wherein: the microcomputer is configured to switch the brushless motor between operating and stopping in response to movement of the movable switch(es), linked to the manipulatable member.
4 . The control module for a power tool according to claim 3 , wherein: the one or more movable switches include: a power switch, which electrically connects and disconnects the brushless motor and the battery; and a variable speed switch, which controls the output of the brushless motor in accordance with the amount by which the manipulatable member is moved.
5 . The control module for a power tool according to claim 1 , wherein: the cover is provided on a first end portion of the case; a wall part of the cover peripheral walls, which is located at an intermediate portion of the case, extends into the interior of the case and is bonded to the circuit board by a sealed part; and a second end portion of the case that is not covered by the cover is covered by a resin molding.
6 . The control module for a power tool according to claim 1 , wherein: the manipulatable member is a trigger that is manipulated by pulling; the trigger has a rod, which passes between the case and the cover; and the rod is physically connected to the movable switch(es) in the enclosed space and is movable in the axial direction of the rod.
7 . The control module for a power tool according to claim 6 , wherein: anti-dust grease is provided between the rod and the case and between the rod and the cover.
8 . The control module for a power tool according to claim 1 , further including: a spring that biases the manipulatable member, wherein the spring is disposed in the enclosed space.
9 . The control module for a power tool according to claim 1 , wherein: the movable switch(es) is/are disposed on a first end portion of circuit board; and the microcomputer is mounted on a second end portion of the circuit board so as to be farther away from the movable switch(es) than the FETs.
10 . The control module for a power tool according to claim 1 , wherein: the case has case protrusions that project toward the circuit board so as to avoid screws provided in the main body of the power tool; and the circuit board has board recesses into which the case protrusions are respectively inserted, such that the case protrusions and the board recesses position the circuit board relative to the case.
11 . The control module for a power tool according to claim 1 , further comprising: a capacitor, which temporarily stores charge to be supplied to the brushless motor, provided on the circuit board, the capacitor being located outside of the enclosed space.
12 . The control module for a power tool according to claim 11 , wherein: the capacitor has a capacitance of 100 μF to 1200 μF.
13 . The control module for a power tool according to claim 1 , wherein: the FETs are located outside of the enclosed space, and on a main surface of the circuit board, which faces the opening of the case, and the FETs are covered by a resin molding.
14 . The control module for a power tool according to claim 1 , wherein: the FETs include first FETs and second FETs provided along the circuit board, such that an elongation direction of the second FETs is inclined by 80 to 100 degrees relative to an elongation direction of the first FETs; and a heat sink is overlaid so as to span the first FETs and the second FETs.
15 . A power tool, including: a grip extending from a tool body, wherein: the control module according to claim 1 is disposed within the grip; and the cover and the manipulatable member are disposed at one end side of the control module.
16 . The power tool according to claim 15 , further including: a sensor board having at least one sensor configured to detect the rotational speed of the brushless motor; and a first lead, which extends from the sensor board to a position on the circuit board outside of the enclosed space.
17 . The power tool according to claim 15 , further including: a lamp; and a second lead, which extends from the lamp to a position on the circuit board outside of the enclosed space.
18 . The control module for a power tool according to claim 1 , wherein the guide pieces are located within the enclosed space.
19 . The control module for a power tool according to claim 18 , wherein: first and second ribs on the case support the circuit board; the circuit board has a first notch on a first side surface and a second notch on a second side surface; a first one of the guide pieces is fitted within the first notch of the circuit board and is also fitted between the first rib and a first one of the case peripheral walls; and a second one of the guide pieces is fitted within the second notch of the circuit board and is also fitted between the second rib and a second one of the case peripheral walls.
20 . A control module for a power tool, including: a box-shaped case, one side of which is open; a circuit board housed in the case; a microcomputer and field effect transistors (FETs), which are mounted on the circuit board and are configured to control a brushless motor of the power tool; a manipulatable member, which is movable relative to the case; one or more movable switches electrically connected to the circuit board and mechanically linked to movement of the manipulatable member; a cover, which partially overlays the case opening so as to cover a portion of the circuit board and so as to cover the movable switch(es); and bonded parts that form an enclosed space, which encloses the movable switch(es), by welding or otherwise materially bonding the cover to the case; wherein: the FETs include first FETs and second FETs provided along the circuit board, such that an elongation direction of the second FETs is inclined by 80 to 100 degrees relative to an elongation direction of the first FETs; and a heat sink is overlaid so as to span the first FETs and the second FETs.

Description

CROSS-REFERENCE The present application claims priority to Japanese patent application serial number 2024-020156 filed on Feb. 14, 2024, the contents of which are hereby fully incorporated by reference. TECHNICAL FIELD The present invention relates to a power tool and to a control module for a power tool. The control module integrally comprises a circuit board and trigger, which are, for example, associated with the control of a power tool motor. BACKGROUND ART A power tool disclosed in European Patent No. 2946886 has a brushless motor and a control module. The control module has a case that is open at the top and a circuit board that is housed in the case. FETs (field effect transistors), which are used to control the brushless motor, are provided on the circuit board. The control module further has a trigger and an actuator, which is movable in conjunction with the operation (movement) of the trigger. The actuator is connected to the circuit board and is covered by a cover. The cover is connected to the case by snap fitting. The actuator is provided in the enclosed space formed by the cover and the case, to protect the actuator. SUMMARY OF THE INVENTION However, snap fit connection may leave a gap between the cover and the case, such that the enclosed space may not be adequately dustproof or waterproof. Therefore, poor conduction may eventually occur at the contacts due to corrosion or covering caused by dust or water that has entered the enclosed space. There is, therefore, a need for a control module that can adequately dustproof or waterproof the enclosed space formed by the cover and the case. According to one aspect of the present disclosure, a control module for a power tool includes a box-shaped case, one side of which is open, and a circuit board housed in the case. A microcomputer and FETs (field effect transistors), which are used to control a brushless motor of the power tool, are mounted on the circuit board. A manipulatable member (e.g., a trigger) is movably coupled to (partially disposed in) the case. Movable switches, which are mechanically linked to the movement of the manipulatable member, are connected to the circuit board; i.e. the movable switches preferably move together with the manipulatable member. The cover is partially overlaid on the opening of the case. The cover covers a portion of the circuit board and covers the movable switches. The control module further includes bonded parts, which weld or bond the cover and the case. The bonded parts form an enclosed space, which encloses the movable switches. With regard to the bonded parts, at least portions of the cover and the case are melted so as to be welded to each other, or a bonding agent is used to bond the cover and the case to each other. Therefore, gaps between the cover and the case are filled by the bonded parts. Accordingly, the enclosed space is formed between the cover and the case. The enclosed space is more dustproof and waterproof than, for example, an enclosed space in which the cover and the case are connected to each other by snap fitting. The movable switches are protected by the enclosed space, more particularly by the case, cover and bonded parts. Thus, poor conduction caused by the ingress of dust or water is unlikely to occur in the movable switches. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a right side view of a power tool according to the present disclosure, with the right side housing removed. FIG. 2 is an exploded perspective view of the control module disassembled from the power tool. FIG. 3 is a right side view of the control module. FIG. 4 is a perspective view of the control module. FIG. 5 is an exploded perspective view of the control module. FIG. 6 is an exploded perspective view in which FIG. 5 is seen from the left side. FIG. 7 is a cross-sectional view along the line VII-VII in FIG. 3. FIG. 8 is a view of the cover and the trigger, seen from the left side. FIG. 9 is a view corresponding to FIG. 8, showing the state in which the trigger has been pulled. FIG. 10 is an enlarged view of the upper region of the circuit board. FIG. 11 is a perspective view corresponding to FIG. 4 showing the state in which the FETs are covered with a heat sink. FIG. 12 is a perspective view showing the heat sink in another exemplary embodiment. FIG. 13 is a perspective view showing the heat sink in yet another exemplary embodiment. FIG. 14 is a perspective view showing the heat sink in yet another exemplary embodiment. DETAILED DESCRIPTION OF THE INVENTION According to another aspect of the present disclosure, a microcomputer (microprocessor, memory, etc.) and FETs are provided on the circuit board at positions clear (outside) of the enclosed space. Consequently, when the microcomputer and the FETs generate heat during operation of the power tool, the microcomputer and the FETs can effectively dissipate the heat, because the microcomputer and FETs are not disposed in the enclosed space of the control module. Accor