Power screw driver

Abstract

A power screwdriver includes a housing having a vacuum chamber arranged to communicate with a source of sub-atmospheric pressure. The power screwdriver includes a motor, a bit drive spindle, and a bit supporting sleeve connected to the bit drive spindle. The rear end part of the bit supporting sleeve is surrounded by the vacuum chamber. The bit supporting sleeve is journaled by a bearing between a forward end part and a rear end part of the bit supporting sleeve. The bit supporting sleeve includes at least one longitude vacuum passage extending from its rear end part to its forward end part.

Claims

1. A power screwdriver comprising: a housing having a vacuum chamber arranged to communicate with a source of sub-atmospheric pressure; a motor; a bit drive spindle; a bit supporting sleeve connected to the bit drive spindle, wherein a rear end part of the bit supporting sleeve is surrounded by the vacuum chamber; and a bearing journaling the bit supporting sleeve between a forward end part and the rear end part of the bit supporting sleeve, wherein the bit supporting sleeve comprises at least one longitude vacuum passage extending from the rear end part to the forward end part of the bit supporting sleeve, and wherein the at least one longitude vacuum passage is a track in an external surface of the bit supporting sleeve.

2. The power screwdriver according to claim 1, wherein the bit supporting sleeve comprises a plurality of longitude vacuum passages.

3. The power screwdriver according to claim 2, wherein the plurality of longitude vacuum passages are symmetrically arranged on the bit supporting sleeve.

4. The power screwdriver according to claim 1, wherein the longitude vacuum passage is rounded in the rear end part and in the forward end part of the bit supporting sleeve.

5. The power screwdriver according to claim 1, wherein the bearing is arranged to not allow air to pass through the bearing.

6. The power screwdriver according to claim 1, wherein the bearing is adjacent a front end of the power screwdriver.

7. The power screwdriver according to claim 6, wherein a spring pushes on a ring shaped element surrounding the bit supporting sleeve, and the ring shaped element rests on an inner side of the bearing.

8. The power screwdriver according to claim 1, wherein the bit supporting sleeve is surrounded by a spring on the rear end part, and wherein the spring forces the bit supporting sleeve towards the bit drive spindle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will now be described in more detail and with reference to the accompanying drawings, in which:

(2) FIG. 1 shows a power screw driver according to prior art.

(3) FIG. 2 shows a longitudinal section view of an exemplary embodiment of the power screw driver.

(4) FIG. 3 shows a front end of an exemplary embodiment of the power screw driver 10.

(5) FIG. 4 shows an exemplary embodiment of a bit supporting sleeve.

DETAILED DESCRIPTION

(6) FIG. 1 illustrates a power screw driver according to prior art. As can be seen the housing has at its forward output end a vacuum activated screw pick-up device. The housing is also provided with a means for connecting the screw driver to a power supply and for connecting the screw pick-up device to a source of sub-atmospheric pressure. At its forward end the power screw driver carries a screw engaging bit surrounded by a suction nozzle for picking up and holding a screw to be mounted and tightened. As illustrated in FIG. 1, the housing of the prior art power screw driver extends to a position rather close to the output end of the screw engaging bit. This means that when tightening screws it is difficult to reach tight positions since the housing easily gets into contact with structure parts adjacent the intended screw position. Thus obstructing the screw driver from being used in such positions.

(7) FIG. 2 illustrates an exemplary embodiment of a power screw driver 10 according to the present disclosure. As can be seen the power screw driver 10 according to the present disclosure has a slim design. The power screw driver 10 comprises a vacuum chamber 31, and a bit drive spindle 22 extending through the vacuum chamber 31. The bit drive spindle 22 is connectable to a screw engaging bit (not shown) via a for instance a half-moon coupling 25 for transferring a tightening torque to a screw being tightened. The power screw driver further comprises a bit supporting sleeve 26.

(8) FIG. 3 illustrates an exemplary embodiment of a front end of the power screw driver 10 according to the present disclosure.

(9) In one exemplary embodiment the bit supporting sleeve 26 is rigidly secured to the drive spindle 22 via a press fit. The bit supporting sleeve is journaled with respect to the housing 10 via a bearing 27. The bit supporting sleeve 26 comprises a forward end part 26a and a rear end part 26b. The forward end part 26a surrounds the bit. The rear end part 26b of the bit supporting sleeve 26 is surrounded by a vacuum chamber 31 which is formed as a part of the housing 10 and which communicates with an external source of sub-atmospheric pressure.

(10) Moreover, the bit supporting sleeve 26 comprises at least one longitude vacuum passage 28 extending from its rear end part 26b to its forward end part 26a. The at least one longitude vacuum passage 28 in the bit supporting sleeve 26 form a vacuum path from the forward end part 26a to an external source of sub-atmospheric pressure via the vacuum chamber 31.

(11) By providing a vacuum path to the forward end part 26a via the at least one longitude vacuum passage 28 it has been possible to locate the arrangement (not shown) using the vacuum to fetch the screw at an axial distance from the vacuum chamber 31. Thus a forward end section of the housing 10 can be made slim.

(12) This means that access to screws located in narrow and difficult to reach positions has been very much facilitated, because the screw driver is not obstructed by the housing interfering with structure parts adjacent such screw locations.

(13) According to one exemplary embodiment, the at least one longitude vacuum passage 28 is a track in the surface of the bit supporting sleeve 26. In yet another exemplary embodiment of the power screw driver 10, the bit supporting sleeve 26 comprises several longitude vacuum passages. An advantage of having several longitude vacuum passages is that a better air flow can be achieved from the forward end part 26a to the rear end part 26b of the bit supporting sleeve 26.

(14) In a further exemplary embodiment of the power screw driver 10, the several longitude vacuum passages 28 are symmetrically arranged on the bit supporting sleeve 26. By symmetrically arranging the several longitude vacuum passages 28 imbalance of the bit supporting sleeve 26 can be avoided.

(15) In yet another exemplary embodiment of the power screw driver 10, the longitude vacuum passage 28 are rounded in the rear end part 26b and in the forward end part 26a of the bit supporting sleeve 26. The rounded shape of vacuum passage can be obtained by different processes. Milling with a spherical head can obtain a semi-spherical geometry at the end of the milling track creating the rounded end creating a smooth transition for the air flow. An advantage by the longitude vacuum passage 28 being rounded in the rear end part 26b and in the forward end part 26a is that turbulence is reduced.

(16) Turbulence has a negative effect of reducing air flow through the longitude vacuum passage 28.

(17) In a further exemplary embodiment of the power screw driver 10 the bearing 27 is arranged to not allow air to pass through the bearing 27. An advantage by the bearing 27 being air tight is better air flow through the longitude vacuum passage 28. In a further exemplary embodiment of the power screw driver 10 the bearing 27 is adjacent a front end of the power screw driver 10. According to one exemplary embodiment, the bit supporting sleeve is surrounded by a spring 37 on the rear end part 26b, wherein the spring forces the bit supporting sleeve 26 towards the bit drive spindle 22. In yet another exemplary embodiment the spring 37 pushes on a ring shaped element 36 surrounding the bit supporting sleeve 26, the ring shaped element 36 rests on an inner of the bearing 27 at the rear end part 26b.

(18) FIG. 4 illustrates an exemplary embodiment of the bit supporting sleeve 26 and the bearing 27 in the power screw driver 10. As can be seen in FIG. 3, in this exemplary embodiment the bit supporting sleeve 26 comprises longitude vacuum passages 28 that are rounded in the rear end part 26b and in the forward end part 26a of the bit supporting sleeve 26. The longitude vacuum passages 28 are arranged as tracks in the surface of the bit supporting sleeve 26. Thus as can be seen from the figure on the inside of the bearing 27.