JP3115937B2 - Screw tightening tool - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw tightening tool such as an electric screwdriver or an electric wrench, and more particularly to a screw tightening tool capable of performing a manual tightening operation by locking an output shaft.

[0002]

2. Description of the Related Art In a screw tightening tool such as an electric screwdriver or an electric wrench, it is possible to lock the rotation of an output shaft so that it can be used as a hand-rotated type, and the tightening and electric force by the sense of a hand can be used. This is very useful because it becomes possible to perform auxiliary tightening by hand when the tightening is not complete. In order to provide such a locking function, as shown in JP-A-3-251374, the input shaft side member and the output shaft side member located coaxially are connected with a play within a predetermined angle. And a wedge-shaped member that allows the lock member to bite and play between the inner peripheral surface of the non-rotatable ring body surrounding the output shaft side member and the outer peripheral surface of the output shaft side member. A space is formed, and the input shaft side member is formed with a release member that pushes the lock member toward the floating region side in the wedge-shaped space portion, so that when the motor is rotated in the locked state, the lock is automatically released. It is preferable in terms of usability that the automatic release to be performed and the automatic lock to be automatically locked when the motor is stopped are performed.

[0003]

However, in the above-mentioned tool, since the output shaft is completely locked when the tool is locked, it is not possible to adjust the tightening torque at the time of manual tightening. The present invention has been made in view of such a point, and an object of the present invention is to make it possible to adjust a tightening torque at the time of manual tightening work and to divert a member for locking an output shaft. An object of the present invention is to provide a screw tightening tool which realizes an adjusting function and can adjust a tightening torque with a small number of parts.

[0004]

According to the present invention, there is provided a power transmission connecting portion which is connected to an input shaft side member and an output shaft side member located coaxially with a play within a predetermined angle. In addition , a wedge-shaped space is formed between the inner peripheral surface of the ring body surrounding the output shaft side member and the outer peripheral surface of the output shaft side member to allow the locking member to bite and play freely. In a screw tightening tool having a release member that pushes a lock member toward a floating region side in a wedge-shaped space, a ring body is rotatably disposed around its axis, and a ring is provided.
A rotation restricting member for restricting rotation of the ring body by engaging with the body;
Urges the rotation restricting member in the direction of engagement with the ring body
The feature is that a spring member is provided.

[0005]

According to the present invention, when the output shaft is locked and hand tightening is performed, if the tightening torque determined by the spring load applied to the ring is exceeded, the ring starts rotating and the output shaft is locked. Invalidate.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiment. A sun gear 31 fixed to an output shaft 20 of a motor 2 will be described.
And the internal gear 3 fixed to the inner surface of the gear case 6
3, a plurality of planetary gears 32 meshing with each other, and a carrier 3 having a shaft 35 for supporting each planetary gear 32.
4 is provided as deceleration means, and the carrier 34 and the chuck 8 in this planetary mechanism are provided.
Are arranged coaxially in the axial direction. In the figure, 6 is a gear case, 61 is a sliding bearing for receiving an output shaft, 62 is a thrust plate, 63 is a retaining ring, 64, 65,
Reference numeral 66 denotes a steel ball and a retainer constituting the thrust bearing.

As shown in FIG. 2, a plurality of projections 70 project radially and at equal intervals from the outer peripheral surface of the end of the output shaft 7 on the side of the carrier 34. On the inner surface of the gear case 6, a ring body 51 surrounding the outer periphery of the projection 70 is provided. The end face of the carrier 34 is provided with a plurality of projections 36 projecting in the axial direction and located in a space between the inner peripheral surface of the ring body 51 and the outer peripheral surface of the output shaft 7. The same number of the protrusions as the above-mentioned protrusions 70 are formed at equal intervals in the circumferential direction and are located between the respective protrusions 70 of the output shaft 7, that is, the protrusions 36 and the protrusions 70 are spaced apart in the circumferential direction. The projections 36 and 70 form a rotational power transmission connecting portion having a play at a predetermined angle in the rotational direction.

The ring body 51 is disposed in the gear case 6 so as to be freely rotatable around an axis, and has an uneven clutch surface 37 on the front end face in the axial direction. ing. An axial hole 62 is provided in the gear case 6, and a steel ball 74 that engages with the clutch surface 37 is provided in the hole 62. A clutch plate 77, a clutch spring 76, and a thrust plate 75 are provided on the outer periphery of the front end of the gear case 6. The clutch plate 77 is rotatably provided at the front end of the main body 1. It is engaged with a step-like projection 80 formed on the inner surface of the handle 78. In the figure, reference numeral 79 denotes a mounting plate for the clutch handle 78. The clutch spring 76 presses the steel ball 74 via the thrust plate 75 and applies a spring load to an engagement portion between the steel ball 74 and the clutch surface 37 to stop the rotation of the ring body 51. Therefore, in a steady state, the ring body 51 is fixed and does not rotate.

Here, a projection 70 on the output shaft 7 is provided.
The outer peripheral surfaces on both sides of the inclined surface 7 on which the projection 70 side becomes lower, respectively.
Therefore, a wedge-shaped space is formed between the outer peripheral surface and the inner peripheral surface of the ring body 51 on both sides of the projection 70, and the projections 36 of the carrier 34 are formed on both sides of the projection 70. In these wedge-shaped spaces provided between the projections 70 and the projections 70, respectively, roller-shaped locking members 50a and 50b are provided to form locking means 5. Note that the lock member 50a is for locking in one direction,
0b is for locking in the other direction rotation. This lock member 5
Since the diameters of the protrusions 0a and 50b are smaller than the height of the portion of the wedge-shaped space on the protrusion 70 side and larger than the height of the portion of the wedge-shaped space on the protrusion 36 side, the lock members 50a and 50b are
When it is located on the zero side, it is in a floating state, but when it is separated from the projection 70, it is engaged between the outer peripheral surface of the output shaft 7 and the inner peripheral surface of the ring body 51 to lock the output shaft 7.

FIG. 6 shows the appearance, in which 1 is a main body,
9 is a bit mounted on the chuck 8, 11 is a switch handle, 12 is a rotation direction switching handle, and 13 is a power pack. Next, the operation will be described. Now, if the motor 2 is rotated, this output is decelerated by the planetary mechanism to rotate the carrier 34, and the protrusion 36 of the carrier 34 is connected to the protrusion of the output shaft 7 via the lock member 50b as shown in FIG. Pressing 70 causes the output shaft 7 to rotate. At this time, of the pair of lock members 50a and 50b located in the wedge-shaped space portions on both sides of the protrusion 70, the lock member 50b is positioned in the floating region in the wedge-shaped space portion, that is, the portion near the protrusion 70 by being pushed by the protrusion 36. , Lock member 5
Oa is located in the floating region in the wedge-shaped space due to its inertia, and therefore, the lock members 50a, 5a
0b does not hinder the rotation of the output shaft 7.

In particular, here, the projections 70 and the projections 36 have a substantially sector shape in which the width on the outer peripheral side is wider than the width on the inner peripheral side and the difference is larger than the difference caused by the difference in the radial position. The projections 36 and 70 generate a force for pressing the lock members 50 a and 50 b, which are both roller-shaped, against the outer peripheral surface of the output shaft 7.
There is no loss of force caused by the contact of the ring 50b with the inner peripheral surface of the non-rotatable ring body 51.

When the direction of rotation of the motor 2 is reversed, FIG.
As shown in FIG.
The power is transmitted to the output shaft 7 through the first and second shafts to rotate the output shaft 7. At this time, the two lock members 50a, 50
Since b is located on the floating region side in the wedge-shaped space, no lock is made. Then, if the main body 1 is rotated in the tightening direction around the axis of the output shaft 7 to perform manual tightening with the motor 2 stopped, the main body 1, that is, the ring body 51 and the output shaft 7 are connected to each other. As shown in FIG.
While the lock member 50a keeps its position in the floating region near the projection 70, the lock member 50a separates from the projection 70 by the rolling caused by the relative rotation and moves to the biting portion side in the wedge-shaped space portion. 51 and the output shaft 7 are integrated. That is, the free rotation of the output shaft 7 is controlled by the locking member 50a.
As a result, it is locked and rotates with the main body 1, and the screws and nuts can be manually tightened. The transition to the locked state is automatically performed as described above.

When the main body 1 is turned in the opposite direction to loosen the screws and nuts, as shown in FIG.
b locks the output shaft 7 and enables hand return. Then, if the motor 2 is rotated again in the locked state, the rotation of the output shaft 7 causes the protrusion 70 to approach the lock members 50a and 50b and is at the engagement position for locking. To return the lock members 50a and 50b to the floating region in the wedge-shaped space,
The lock member 5 in which the protrusion 36 in the position 4 is in the biting position
In order to push back Oa and 50b back to the floating region side of the wedge-shaped space, the lock is automatically released. The projection 36 is a power transmission member and also a release member, so that cost reduction by reducing the number of parts can be obtained.

When hand-tightening is performed by hand while the output shaft 7 is locked, when the load torque required to rotate the screws and nuts is small, as described above, the ring body 51 and the steel ball 74 are used. The rotation of the ring body 51 is stopped by maintaining the engagement state with the ring body 51. However, if the load torque is larger than the set torque due to the above-mentioned spring load, the ring body 51 causes the steel ball 74 to The rotation of the ring body 51 and the output shaft 7 with respect to the body 1 starts rotating while being pushed back against the clutch spring 76, and the force by hand tightening is not transmitted to the output shaft 7 due to the idling of the ring body 51 and the output shaft 7; The tightening torque is limited to the set torque.

When the clutch handle 78 is rotated, the engagement position between the step-like projection 80 on the inner surface of the clutch handle 78 and the clutch plate 77 which is stopped from rotating around the axis changes, and the clutch plate 77 is moved in the axial direction. Moving, clutch spring 7
Since the amount of compression changes, the set torque can be adjusted. If the torque adjustment is unnecessary, the clutch handle 78 may be disabled from rotating with respect to the main body 1 or may be integrated with the main body 1.

[0016]

As described above, in the present invention, when the output shaft is locked and hand tightening is performed, if the tightening torque determined by the spring load applied to the ring is exceeded, the ring starts rotating. In order to invalidate the lock of the output shaft, it is possible to adjust the tightening torque at the time of manual tightening work, and furthermore, this adjustment function is realized using a ring body that is a member for locking the output shaft. Therefore, the tightening torque can be adjusted with a small number of parts.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of one embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a release state at the time of forward rotation of the above.

FIG. 3 is a sectional view showing a release state at the time of reverse rotation of the above.

FIG. 4 is a cross-sectional view showing a locked state when the above is manually tightened.

FIG. 5 is a cross-sectional view showing a locked state at the time of hand return according to the first embodiment.

FIG. 6 is a side view of the same.

[Explanation of symbols]

 7 Output shaft 50a Lock member 50b Lock member 51 Ring body 76 Clutch spring

Claims (2)

(57) [Claims] 1. A provided with a connecting part for power transmission is coupled with play in a predetermined angle to the input shaft side member located coaxially with the output shaft side member, a ring member surrounding the output shaft side member A wedge-shaped space portion is formed between the inner peripheral surface of the shaft member and the outer peripheral surface of the output shaft side member to allow the lock member to bite and play. The input shaft side member includes the lock member on the side of the floating region in the wedge-shaped space portion. In a screw tightening tool that has a release member that pushes the ring, the ring is rotatably arranged around its axis and is engaged with the ring to regulate the rotation of the ring.
Rotation restricting member and the rotation restricting member
A screw tightening tool comprising a spring member for urging in a direction of engagement . 2. The rotation is restricted by changing the initial compression amount of the spring member.
2. The screw tightening tool according to claim 1 , wherein an engagement force between the member and the ring body is variable.