JPH0420749B2 - - Google Patents

Description

Detailed Description of the Invention [Technical Field] The present invention relates to an electric screwdriver, and particularly to an electric screwdriver equipped with a locking means for locking the rotation of an output shaft and a torque adjustment means for adjusting the tightening torque. It is.

[Background technology] Being able to lock the rotation of the output shaft of an electric screwdriver allows it to be used as a hand-crank type, allowing for tightening by feeling with the hand or for auxiliary tightening when electric power is not enough. It is very useful for learning to understand.
In order to lock the rotation of the output shaft,
Utilizing a planetary mechanism, the lock is normally locked, but is automatically unlocked when the motor is rotated, thereby eliminating the increase in effort required during use due to the provision of a locking means. This is disclosed in Japanese Patent Application Laid-Open No. 59-53164.

On the other hand, it is also very useful for an electric screwdriver to have the ability to adjust the tightening torque. For this reason, the device disclosed in the above publication also incorporates a torque adjustment means for adjusting the tightening torque. However, in the one shown here, the locking means and the torque adjusting means are provided as mutually independent mechanisms,
For this reason, the device has become complicated with a large number of parts, the overall size has become large, and assembly has become labor-intensive.

[Object of the Invention] The present invention has been made in view of the above points, and its purpose is to reduce the number of parts and downsize the mechanism by integrating both the locking means and the torque adjusting means. The purpose of the present invention is to provide an electric screwdriver that is lightweight.

[Disclosure of the Invention] Accordingly, the present invention includes a planetary mechanism including a sun gear, an internal gear, a planetary gear that meshes with both of these gears, and a carrier that supports the planetary gear. at least a pair of locking members for preventing the output portion from rotating in each direction, an urging member for urging both lock members in the direction of engagement with the output portion, and a biasing member for disengaging the lock member from the output portion. The planetary mechanism includes a locking means consisting of a cam member provided on a freely rotatable internal gear, and further includes a locking protrusion provided on the internal gear and is locked by a spring bias toward the internal gear. The locking member is equipped with a torque adjusting means consisting of an engaging member that regulates the rotation of the internal gear according to the torque value by engaging with the protrusion, and the locking member is rotatable about its shaft. The cam member is provided on the inner peripheral side of one end surface of the internal gear so that it can pass freely through the portion where the lock member is located while rotating the lock member, and the cam member is further provided with the locking protrusion. The locking means and the torque adjusting means include a plurality of engaging members provided at intervals on the outer circumferential side of one end surface of the internal gear and disposed between these locking protrusions. The feature is that the internal gear in a single planetary mechanism is shared.

The present invention will be described below in detail based on the illustrated embodiment. The illustrated example is an electric screwdriver that can also be used as an electric drill, and as shown in FIG. A main body portion 10 and a grip portion 1 protruding from the main body portion 10
1, a clutch handle 78 is provided at the front end of the main body 10 so as to be rotatable around the axis of the main body 10, and a power pack 9 is attached to the rear end of the main body 10. The driver bit or drill bit is a chuck 8 arranged at the front end of the main body 10.
can be attached to. In the figure, 12 is a switch handle.

FIG. 9 shows a power system assembly disposed within the main body 10 of the housing 1. As shown in FIG. It consists of a motor 2, a gear case 6, and the clutch handle 78 and chuck 8. Disposed within the gear case 6 are a reduction section 3 having a speed change function and a clutch section 4 having a locking means.

Based on FIG. 1 and FIG. 2, these reduction parts 3
The clutch portion 4 will now be explained. First, the gear case 6 includes a cylindrical case 61 and a case 6.
A case 62 is connected to the front end of the case 61 by a mounting screw 64, and a motor mounting base 60 is mounted on the rear side of the case 61. Further, the case 61 has a pair of elongated holes 63 that are long in the axial direction.
A pair of support pins 65 are provided that protrude from the outer surface, and the case 62 is provided with a plurality of holes 67 passing through it in the axial direction. It is integrally protruded.

The speed reducer 3 installed in the case 61 of the gear case 6 is composed of a two-stage planetary mechanism, and the first stage planetary mechanism is a sun gear 31 fixed to the output shaft 20 of the motor 2. And case 6
1, a plurality of planetary gears 32 meshing with both of them, and a carrier 34 equipped with a shaft that supports each planetary gear 32.
The second stage planetary mechanism is composed of a sun gear 35 integrally formed with a carrier 34, an internal gear 37, a planet gear 36, and a carrier 38.

Here, while the internal gear 33 is fixed to the case 61 as described above,
The internal gear 37 is rotatable around its axis, and a sliding ring 50 surrounding the internal gear 37 is connected to its outer peripheral surface. This sliding ring 50 is provided with a plurality of engaging protrusions 51, three in the illustrated example, at equal intervals in the circumferential direction on its inner circumferential surface.
By engaging the engagement protrusion 51 with the engagement groove formed on the outer peripheral surface of the internal gear 37
They are configured to rotate together and to be able to freely slide in the axial direction relative to the internal gear 37. Note that the sliding ring 50 is always engaged with the internal gear 37 regardless of its sliding movement. Further, the outer peripheral surface of the sliding ring 50 is received by a plurality of roller pins 71 arranged at intervals on the inner peripheral surface of the case 61.

The axial movement of the sliding ring 50
This is done by a lever 55 whose tip is engaged with an annular groove 52 formed on the outer peripheral surface of the roller 56 via a roller 56. The lever 55, which is U-shaped and has a handle 58 connected to its center, is connected to the case 61.
Both sides are rotatably supported by a pair of support pins 65 protruding from the outer surface of the case 61, and rollers 56 are attached to the U-shaped folded ends of both sides. The sliding ring 50 is engaged through the elongated hole 63 formed.
Since it is made of wire, it has spring properties.

On the other hand, a plurality of locking protrusions 54 and 53 are provided on the outer peripheral surface of the carrier 34 and on the inner surface of the case 61, respectively. These engaging protrusions 54 and 53 selectively engage with the engaging protrusion 51 when the sliding ring 50 slides in the axial direction. sliding ring 50
When the internal gear 37 is moved forward and the engagement protrusion 51 is engaged with the engagement protrusion 53 provided on the case 61, the sliding ring 50 prevents the internal gear 37 from rotating. Conversely, when the sliding ring 50 is moved backward by advancing the central portion of the lever 55 and the engagement protrusion 51 is engaged with the engagement protrusion 54 of the carrier 34, the internal gear 37 and the carrier 34 are integrally provided. The sun gear 35 is connected to the sun gear 35.

In the former case, the second-stage planetary mechanism also effectively decelerates, resulting in a large reduction ratio, and in the latter case, the planetary gear 36 does not rotate around its axis (rotation). , Taiyo Gear 3
5 and the carrier 38 are directly connected, the reduction ratio becomes small. It is equipped with a speed change function.

Next, the clutch portion 4 according to the present invention will be explained. This clutch section 4 also utilizes a planetary mechanism like the speed reduction section 3. First, the planetary mechanism disposed inside the case 62 consists of a sun gear 40 and an internal gear that are integrally formed on the carrier 38. 42, a plurality of planetary gears 41 that mesh with these two, and a carrier 43 that supports each planetary gear 41
It is made up of.

The locking means includes a plurality of cam protrusions 47 protruding from the inner periphery of the front end of the internal gear 42 at equal intervals in the circumferential direction, and a pair of locking pins 45a rotatably attached to the inner surface of the case 62. , 45b, the central part is supported by the case 62, and both ends are connected to the respective lock pins 45a, 45b.
A locking ring 44 is connected to the output shaft 7 together with the carrier 43 so as to rotate integrally with the output shaft 7.

As shown in FIG. 3, each of the lock pins 45a, 45b engages with teeth on the outer circumferential surface of the lock ring 44 with their tips facing each other.
5a prevents the lock ring 44, that is, the output shaft 7, from rotating in the counterclockwise direction in the drawing, and the lock pin 45b prevents the output shaft 7 from rotating in the clockwise direction in the drawing. When both the lock pins 45a, 45b are engaged with the lock ring 44, the output shaft 7, to which the chuck 8 is fixed by the mounting screw 80, is locked against rotation in both directions. That's why.

Further, the torque adjustment means is an internal gear 42.
a plurality of locking protrusions 48 protruding from the outer periphery of the front end at equal intervals in the circumferential direction; and steel balls 7 disposed in the plurality of holes 67 formed in the case 62.
4. A thrust plate 75, a clutch spring 76, and a clutch plate 77 that are placed over the irregularly shaped platform portion 66 of the case 62.
and the clutch handle 78.

The clutch handle 78 is configured to be able to freely rotate within a predetermined angle between the front end surface of the gear case 6 and a mounting plate 79 attached to the gear case 6 by a mounting spring 81. When the clutch handle 78 is rotated, the clutch plate 77, which is provided with an engagement portion with the clutch plate 77 and is prevented from rotating due to the engagement with the irregularly shaped base portion 66 of the case 62, moves in the axial direction. It is made to be. The clutch spring 76 is a compression coil spring disposed between the clutch plate 77 and the thrust plate 75, and the clutch spring 76 is a compression coil spring arranged between the clutch plate 77 and the thrust plate 75.
come into contact with. The steel ball 74 engages with the locking protrusion 48 formed on the internal gear 42.

The operation of the locking means and torque adjusting means in the clutch section 4 will be explained. In the stopped state in which the motor 2 is not rotating, the pair of lock pins 45a and 45b are both engaged with the lock ring 44, and the output shaft 7 is locked against rotation in both directions as described above. Therefore, the tightening work can be performed manually. Now, if you try to rotate the motor 2 from this state and rotate the output shaft 7 in the clockwise direction indicated by _T1 in Fig. 4, the output shaft 7 is locked, so this driving force will be This is transmitted to the internal gear 42 via the planetary gear 41, and the internal gear 42 starts rotating in the counterclockwise direction indicated by _T2 in the figure. When the locking protrusion 48 of the internal gear 42 comes into contact with the steel ball 74 biased by the clutch spring 76 and its rotation is stopped, the internal gear 42 locks as shown in FIG.
A cam protrusion 47 is connected to a pair of lock pins 45.
Of the lock pins 45a and 45b, the lock pin 45b is pushed away from the lock ring 44 to release the restriction on rotation of the output shaft 7 in the clockwise direction in the figure. Since the other lock pin 45a does not prevent the output shaft 7 from rotating in this direction, the output shaft 7 starts rotating due to the power from the motor 2.

Thereafter, this state is maintained in the locking means, but when the tightening torque reaches a predetermined value, the internal gear 42 receiving the reaction force starts rotating. In other words, the locking protrusion 48 rides over the spring-biased steel ball 74 and begins to rotate. As a result, the torque transmitted to the output shaft 7 is limited at that point, and the output shaft 7 stops.

Also, at this time, in the locking means, since the cam protrusion 47 rotates, there occurs a point in time when the lock pin 45b, which is biased by the spring 46, re-engages with the lock ring 44, but at this time, the output shaft 7 is stopped. Since there is, there will be no problem. Furthermore, in the case shown here, when the locking protrusion 48 of the internal gear 42 is in the position where it contacts the steel ball 74, the position where any of the cam protrusions 47 releases the engagement between the lock pin 45b and the lock ring 44 is shown. As shown, the locking protrusion 48 and the cam protrusion 4
Since the output shaft 7 is provided in correspondence with the output shaft 7
There is no chance that the device will be inadvertently locked. In addition, when the internal gear 42 starts rotating for torque adjustment, the lock pin 45a
Interference between the cam protrusion 47 and the lock pin 45a,
The contact portion of the cam protrusion 47 at 45b is connected to the arcuate surface 4
9, this is prevented by pushing up the lock pin 45a against the spring 46 no matter which direction the cam protrusion 47 contacts the lock pin 45a.

Next, to explain the operation when the rotating motor 2 is stopped, the position of the cam protrusion 47 at this point is as shown in FIG. 5 before the tightening torque is reached and the internal gear 42 starts rotating. In addition to the case where the internal gear 42 is rotating, there are the following two cases that occur because the internal gear 42 is rotating. This is because the cam protrusion 47 is not pushing up any of the lock pins 45a, 45b.
In the case shown in the figure, the cam protrusion 47 is attached to the lock pin 4.
This is a case where the engagement between the lock pin 45a and the lock ring 44 is released by pushing up the lock pin 45a. The state shown in FIG. 3 does not require any explanation since this is the initial state, but the other two cases are as follows.

In other words, the output shaft 7 is connected to one of the lock pins 4.
5a and 45b are prevented from rotating in one direction by engaging with the lock ring 44, but rotation in the other direction is possible, and at this time, the internal gear 42 is rotated in either direction. is in a state where rotation is possible. At this time, the direction in which the output shaft 7 can rotate and the direction in which the internal gear 42 can rotate are the same, and if the output shaft 7 is slightly rotated in the direction in which it can rotate, the output shaft 7 and the internal gear 42 can rotate together. The rotating carrier 43 rotates the internal gear 42 via the planetary gear 41, and as a result, the cam protrusion 47 is disengaged from the lock pins 45a, 45b, and the lock pins 45a, 45b are returned by the spring 46. The lock pins 45a, 45b and the lock ring 44 are re-engaged, and the output shaft 7 is returned to its initial state where it is locked in both rotational directions.

When the rotational direction of the motor 2 is reversed, the above-mentioned rotational directions are reversed and the roles of the pair of lock pins 45a and 45b are simply reversed, so a description thereof will be omitted. If the locking pins 45a and 45b in the locking means are provided as two pairs symmetrically as shown in FIG. 7, the locking of the output shaft 7 can be well-balanced with respect to the center of rotation. , the lock strength can be improved.

In Fig. 2, 70 and 72 are washers, and 73 is the output shaft 7.
This is a pin whose both ends are inserted into the carrier 43 (sun gear 40).

In the above embodiment, a lock ring 44 is provided as a member that is engaged with the lock pins 45a and 45b, which are lock members, but this lock ring 44 is a member that rotates together with the output shaft 7. In addition, as is clear from the fact that they are members that rotate together with the carrier 43, the lock pins 45a and 45b may be engaged with the carrier 43, or may be engaged directly with the output shaft 7.

[Effects of the Invention] As described above, in the present invention, since the cam member for unlocking can freely pass through the portion where the lock member is located while rotating the lock member, this cam member and a locking protrusion for torque adjustment must be provided on a single internal gear, and the locking means constructed using a planetary mechanism and the internal gear must be completely rotatable. The internal gear can be shared with the torque adjustment means,
Compared to the conventional example which requires two separate planetary mechanisms, the number of parts can be reduced, the structure can be simplified, the ease of assembly can be improved, and the mechanism can be made smaller and lighter.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view of one embodiment of the present invention, Fig. 2 is an exploded perspective view of the same as above, Fig. 3 is a transverse sectional view taken along line A-A in Fig. 1, and Figs. 4 and 5 are 6 is a perspective view of the internal gear shown in the above, FIG. 7 is a cross sectional view showing another embodiment of the locking means, and FIG. 8 is a perspective view showing the entirety of the same. FIG. 9 is a perspective view of the same power system assembly as above, in which 2 is a motor, 3 is a reduction section, 4 is a clutch section, 6 is a gear case, 7 is an output shaft, 40 is a sun gear, 41 is a planetary gear, 42 is internal gear,
43 is carrier, 44 is rock ring, 45a,
45b is a lock pin, 46 is a spring, 47 is a cam projection, 48 is a locking projection, 74 is a steel ball, and 76 is a clutch spring.

Claims (1)

[Claims] 1. A planetary mechanism consisting of a sun gear, an internal gear, a planetary gear that meshes with both of these gears, and a carrier that supports the planetary gear, and that engages with an output section connected to the carrier to control the output section. At least one pair of lock members for preventing rotation in each direction, a biasing member for biasing both lock members in the direction of engagement with the output portion, and a biasing member for disengaging the lock member from the output portion in the planetary mechanism. The lock means includes a cam member provided on a rotatable internal gear, and further includes a locking protrusion provided on the internal gear and a locking protrusion that is biased by a spring toward the internal gear. The lock member is provided with a torque adjustment means consisting of an engagement member that regulates the rotation of the internal gear according to the torque value when The cam member is provided on the inner circumferential side of one end surface of the internal gear and can pass through the portion where the lock member is located while rotating the lock member, and the locking protrusion is provided on the inner circumferential side of one end surface of the internal gear. An electric screwdriver characterized in that a plurality of engagement members are provided at intervals on the outer circumferential side of one end surface, and an engagement member is disposed between these engagement protrusions. 2. The electric screwdriver according to claim 1, wherein the cam member and the locking protrusion provided on the internal gear are provided at positions corresponding to each other. 3. The electric screwdriver according to claim 1, wherein a plurality of pairs of locking means are provided symmetrically with respect to the output portion.