JP2511752Y2 - Electric tool - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an electric tool such as an electric drill or an electric screwdriver having a gear case accommodating a motor and a speed reducer.

[Prior Art] FIG. 8 is a broken side view of a conventional electric power tool of this type, and FIG. 9 is a sectional view thereof. The outer shell formed in a substantially T shape is composed of two casings 1a and 1b, and a gear case 3 accommodating a motor 2 and a speed reducer for reducing the rotation speed of the motor 2 in the upper portion of the casings 1a and 1b. ′ Etc. are provided. The lower portion of the casing 1a, 1b is formed with a grip portion 4 that can be gripped by hand, and the battery 5 is accommodated in the grip portion 4. A switch 6 for turning on / off the power source is provided at a substantially central portion of the casings 1a, 1b, and a push button 7 for driving the switch 6 is exposed to the outside.
A handle 8 for switching the rotation direction of the motor 2 is arranged above the push button 7. A terminal 10 is provided on the rear portion of the motor 2 mounted on the motor mount 9, and the terminal 10 and the switch 6 are connected by a lead wire 11. A chuck 12 is attached by a screw 13 to the output shaft from the speed reducer in the gear case 3 '. Further, the casings 1a and 1b divided into two are connected by a plurality of screws 14.

The gear case 3'of the reduction gear to which the motor 2 of the conventional electric drill or the electric screwdriver is fixed is fixed to the casings 1a and 1b as described above. When the switch 6 is turned on, a rotational torque is generated in the motor casing in a direction opposite to the rotational direction of the motor 2, but the motor 2 is mounted in the gear case 3'of the speed reducer as shown in FIG. In this case, the rotation torque is also transmitted to the gear case 3 ', and the gear case 3'is fixed so as not to rotate in the casings 1a and 1b, thereby fixing the rotation of the motor 2. Casings 1a, 1b of this gear case 3 '
It is fixed to the plate by the method shown in FIG. That is, ribs 15 are integrally formed on the outer side surfaces of both sides of the gear case 3'in the axial direction, and recesses 16 that fit into the ribs 15 are formed on the inner side surfaces of the casings 1a, 1b by projecting two projections 17, 18. It is formed by setting.

[Problems to be Solved by the Invention] In the conventional example, the gear case 3'is rotationally fixed by the rib 15 and the recess 16 in the concavo-convex fitting.
In order to obtain the necessary rotation holding force, these uneven parts are
It is necessary to form a large one, which is not preferable in terms of usability because it leads to a larger outer shape of the electric drill or electric screwdriver. When an internal gear is formed on the inner surface of a cylindrical gear case 3'as shown in FIG. 8 and the planetary gear speed reduction mechanism is used as the speed reducing means, the internal gear is covered and fixed by the gear case 3 '. Whether the motor 2 is mounted on the gear case 3'or not, it is necessary to fix the gear case 3'to the casings 1a and 1b in order to rotationally fix the internal gear. Further, the gear case 3'of the speed reducer is preferably a perfect circle in terms of noise and transmission efficiency, but the ribs 15 and the projections 17 and 18 for forming the recess 16 are formed to fix the rotation. It is necessary to provide it on the outer periphery of ‘, especially in the plastic gear case 3 ′.
This is a major drawback in maintaining a perfect circle.

The present invention has been provided in view of the above points,
(EN) Provided is a power tool which aims to compactly and reliably rotate and fix a gear case by utilizing a dead space of the gear case.

[Means for Solving the Problems] The present invention relates to an electric tool in which a motor and a speed reducer for reducing the rotation speed of the motor are arranged in a casing that is divided into two parts, and a cylindrical gear case accommodating the speed reducer. Is arranged in the casing so that the axial direction is along the split surface of both casings, and both side portions of the gear case sandwiching the split surface of both casings are notched and an intermediate portion is formed in a part of the outer peripheral surface of the gear case in the axial direction. A pair of notches that are left as protrusions along the split surfaces of both casings are formed, and a screw boss that is inserted into each notch of the gear case from both sides that sandwich the split surfaces of both casings inside each casing to sandwich the protrusions. Respectively, and by coupling the two casings by screwing a screw from one of the screw bosses to the screw portion of the other screw boss through an insertion hole formed in the protrusion, The gear case is clamped and fixed by both casings while stopping rotation.

[Operation] Then, by forming a pair of notches in a part of the gear case in the axial direction, the cross-sectional shape of the gear case in the axial direction is made non-circular, and the screw boss projecting into the inside of the two-part casing is notched. Insert the screw into the notch and insert the protruding part left between both notches with both screw bosses, and screw a screw from one screw boss to the screw part of the other screw boss through the insertion hole drilled in the protruding part of the gear case. Thus, the casing is screwed together and at the same time the gear case is prevented from rotating with respect to the casing.
In addition, the protrusion is formed so that the gear case has a non-circular shape,
Since this projection is sandwiched by the casing, and the screw that passes through the casing and the projection is inserted at the part where the projection is sandwiched, the effect of stopping rotation of the gear case with respect to the casing is high, and a large torque acts. However, it is possible to prevent the gear case from rotating with respect to the casing. That is, it becomes possible to provide an electric power tool having a large output torque.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Referring to FIG. 2 showing a broken side view of the entire electric power tool, in the gear case 3, one internal gear 19, a two-stage planetary gear train 20 meshing with the internal gear 19, and a gear case are provided via a bearing 21. A drive shaft 22 is rotatably held by 3 and has a drill bit or a chuck 12 for gripping the drill attached to the tip thereof. The internal gear 19 is provided with a clutch plate 27 that forms a clutch portion together with an adjusting screw 23, a clutch spring 24, a click plate 25, and a steel ball 26, and a clutch handle 28
The clutch spring 24 that is expanded and contracted by the clutch handle 28 and the adjustment screw 23 that is rotationally fixed by the rotation operation of
The internal gear 19 is prevented from rotating by the steel ball 26 biased by the spring force of the motor 2, and the rotation of the motor 2 mounted on the gear case 3 is driven by the pinion and the planetary gear train 20 in two stages.
22. A motor mounting base 29 having the motor 2 attached thereto with screws 30 has a recess 31 at the outer peripheral edge thereof. The recess 31 fits into a rear rib 32 of the gear case 3, and the motor 2 is mounted on the motor mounting base 29. It is fixed to the gear case 3 via.

The gear case 3, which is formed in a cylindrical shape, has a chuck 12
The side is formed to have a small diameter, and a protrusion 33 is integrally formed in a dead space above the side, as shown in FIGS. That is, the protrusion 33 is formed between both cutouts formed by cutting out a part of the outer peripheral surface of the cylindrical gear case 3 from both sides. The projection 33 has an insertion hole 34 through which the screw 35 is inserted in a direction orthogonal to the axial direction of the upper portion of the casing 1a, 1b. A screw boss 36 through which the screw 35 is inserted is formed in a portion corresponding to the protrusion 33 and the insertion hole 34 of the one casing 1a, and the other casing 1b.
The inside is closed, and a screw boss 37 is formed on the inner peripheral surface of which a screw portion to be screwed with the screw 35 is engraved. When the two casings 1a and 1b are combined, both screw bosses 36 and 37
The end faces of the abutting portions are in contact with the side faces of the protrusion 33, respectively.

That is, the projecting portion 33 of the gear case 3 is sandwiched by both screw bosses 36 and 37 projecting from the inner surfaces of the casings 1a and 1b, and the screw 35 is inserted into the screw boss 36 and the insertion hole 34 of the projecting portion 33 to form the screw boss 37. By screwing, the gear case 3 is clamped and fixed by the casings 1a and 1b, and the gear case 3 is fixed.
Will be fixed to the casings 1a and 1b. Therefore,
The gear case 3 is securely fixed to the casings 1a and 1b so that the perfect circular shape of the accommodating portion of the planetary gear train 20 of the cylindrical gear case 3 can be maintained. In addition, in other places of the casings 1a and 1b, the casings 1a and 1b are
Face the screw bosses 38 and 39 protruding from the inner surface of the
The casings 1a and 1b are connected by.

The motor 2 mounted on the gear case 3 has a gap formed between the outer peripheral surface of the motor 2 and the inner peripheral surfaces of the casings 1a and 1b. Several ribs 42 are formed to support the motor 2 that moves by force. These ribs 42 do not normally contact the motor 2 and form a gap. This prevents the vibration of the motor 2 from being directly transmitted to the casings 1a and 1b, and the vibration of the motor 2 is transmitted to the casings 1a and 1b via the gear case 3 having a speed reducing means. The 3 works as a kind of damper. Therefore, the vibration transmitted to the casings 1a and 1b of the motor 2 is reduced by the gear case 3, and the vibrations of the casings 1a and 1b and the accompanying resonance noise can be reduced.

By the way, FIG. 3 shows the clutch plate 27 itself, and FIG. 4 shows the internal gear 19 in which the clutch plate 27 is fitted.
The internal gear 19 has a slit 44 in a ring portion 43 projecting from the end surface of the internal gear 19 for fixing the clutch plate 27 to the internal gear 19.
Are formed at multiple locations. Internal gear by this slit 44
When the ring portion 43 of 19 is provided with a spring property and the clutch plate 27 is incorporated into the internal gear 19, the ring portion 43 falls inward, and when the clutch plate 27 is incorporated into the end surface of the internal gear 19,
The ring portion 43 returns to the outside and presses down on the clutch plate 27 to prevent the clutch plate 27 from coming off and preventing it from rotating.

Further, as shown in FIGS. 5 and 6, in this embodiment, the chuck handle 4 is provided on the outer peripheral surfaces of the casings 1a and 1b.
Along with 5, a drill bit 46 is arranged. FIG. 7 shows a mounting spring 47 for mounting the drill bit 46 on one casing 1a. The mounting spring 47 is formed in a substantially L shape, and the drill bit 4 is formed on both sides of the piece 47a.
The U-shaped elastic contact piece 48 that elastically contacts and fixes 6 is a piece 47a.
A tongue piece 49 is formed at the center of the. The other piece 47b is formed with locking pieces 50 from each of the three sides, and the tips of the locking pieces 50 on both sides are formed by cutting out notches 50a for easy attachment to the casing 1a. The mounting spring 47 is to be mounted in the recess 51 formed on the side surface of the one casing 1a, and the other piece 47b of the mounting spring 47 is brought into contact with the outer surface of the standing wall 52, and the lower portion of the standing wall 52 is perforated. The locking piece 50 of the mounting spring 47 is inserted and locked in a certain insertion hole 53, and the tip of the elastic contact piece 48 is fixed to the side wall 54.
Elastically contact the ceiling surface of the mounting spring 47 with the recess of the casing 1a.
I am trying to attach it to 51. Further, the tip of the tongue piece 49 is made to face the inner surface of the casing 1a to prevent the attachment spring 47 from coming off, and the tongue piece 49 prevents foreign matter such as dust from entering through the gap between the casing 1a and the attachment spring 47. are doing.

As shown in FIG. 6, the drill bit 46 has a casing 1a.
The mounting portion 55 on the bottom surface of the recess 51 is elastically sandwiched between the elastic contact piece 48 and the other piece 47b of the one piece 47a of the mounting spring 47. Further, the bent portion of the central portion of the elastic contact piece 48 of the mounting spring 47 elastically contacts the edge portion of the drill bit 46 so that the drill bit 46 does not easily slip out of the recess 51.

Further, the chuck handle 45 is detachably fitted into the concave portion 56 on the side surface of the casing 1b.

[Advantages of the Invention] As described above, the present invention arranges the cylindrical gear case accommodating the speed reducer in the casing so that the axial direction is along the split surface of both casings, and the axial direction on the outer peripheral surface of the gear case is described. A pair of notches are formed by cutting out both sides of the gear case sandwiching the split surfaces of both casings and leaving a middle portion as a protrusion along the split surfaces of both casings in a part of Forming screw bosses that are inserted into the cutouts of the gear case from both sides that sandwich the split surface of the casing and that sandwich the protrusions, respectively. The two casings are joined together by screwing, and at the same time, the gear case is clamped and fixed while both casings are rotating. By forming the notch portion, the cross-sectional shape of the gear case in the axial direction is made non-circular, and the screw boss protruding inward of the two-piece casing is inserted into the notch portion,
Screw the casing by sandwiching the protrusion remaining between both notches with both screw bosses and screwing the screw from one screw boss to the screw part of the other screw boss through the insertion hole drilled in the protrusion of the gear case. There is an advantage that the rotation of the gear case with respect to the casing can be stopped at the same time when the gear case is coupled. In addition, since the protrusion is formed so that the gear case has a non-circular shape, and the protrusion is sandwiched by the casing, and the screw passing through the casing and the protrusion is inserted at the portion where the protrusion is sandwiched, the gear case is The effect of stopping rotation with respect to the casing is high, and it is possible to prevent the gear case from rotating with respect to the casing even when a large torque is applied. That is,
It is possible to provide an electric tool with a large output torque. Further, the cross-sectional shape of the gear case can be formed into a substantially perfect circle except for a part in the axial direction where the cutout portion is formed, so that the meshing accuracy when using various gears used as a speed reducer, especially a planetary gear train. However, there is an advantage in that it is possible to provide a speed reducer that has good noise and vibration. Moreover, since the above-mentioned effect is obtained by notching a part of the gear case, the casing does not become large, and the gear case can be compactly housed.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is a cutaway side view of the same, FIG. 3 is a perspective view of a clutch plate of the same, and FIG. 4 is an internal gear in which the clutch plate of the same is fitted. FIG. 5 is a perspective view, FIG. 5 is a side view of the same, FIG. 6 is a sectional view of the same, FIG. 7 is a perspective view of a mounting spring of the same, FIG. 8 is a broken side view of a conventional example, and FIG. FIG. 1a and 1b are casings, 2 is a motor, 3 is a gear case, 33
Is a protrusion, 34 is an insertion hole, 35 is a screw, and 36 and 37 are screw bosses.

Claims (1)

(57) [Scope of utility model registration request] 1. A power tool comprising a motor and a speed reducer for reducing the rotational speed of the motor in a casing that is divided into two parts. A cylindrical gear case that houses the speed reducer is divided into two casings in the axial direction. Are arranged in the casing so as to follow the surface, and both side parts of the gear case sandwiching the split surface of both casings are cut out in a part of the outer peripheral surface of the gear case in the axial direction, and the middle part is projected along the split surface of both casings. A pair of notches that are left as parts are formed, and a screw boss that is inserted into each notch of the gear case from both sides that sandwich the split surface of both casings and that sandwiches the protrusion is formed inside each casing. The two casings are joined together by screwing a screw into the threaded portion of the other screw boss through an insertion hole drilled in Electric power tool characterized by being sandwiched and fixed with stop rotating.