TELESCOPIC HAND TOOL

A telescopic hand tool has an inner rod and an outer tube slidable relative to the inner rod. The inner rod is formed with at least one rack gear. The outer tube is formed with a positioning hole. A positioning member is provided in the positioning hole. The positioning member has at least one toothed portion. A control sleeve is slidably fitted on the outer tube. The control sleeve selectively presses the positioning member to make the toothed portion engaged with the at least one rack gear, or selectively releases the positioning member to make the inner rod and the outer tube slidable with each other so that the toothed portion is disengaged from the at least one rack gear and selects a desired meshing point with the at least one rack gear in response to the adjustment. Thus, the length of the telescopic hand tool is adjustable in a stepless manner.

FIELD OF THE INVENTION

The present invention relates to a hand tool, and more particularly to a telescopic hand tool.

BACKGROUND OF THE INVENTION

Most of the telescopic rods of conventional telescopic hand tools adopt steel balls to position the telescopic rods. Through a plurality of positioning notches between the inner tube and the outer tube of the telescopic rod and a positioning steel ball, the positioning steel ball is selectively engaged in one of the positioning notches to change the relative position between the inner tube and the outer tube, thereby adjusting the length of the telescopic rod.

However, this adjustment is limited by the positioning steel ball with certain diameter, so there will be a certain interval between each two positioning notches. As a result, the telescopic rod is constrained by multi-steps when adjusting the length so that the desired length the user required can't be accurately met. Furthermore, the positioning steel ball is in point contact with the telescopic tube, so the contact area is relatively small. When the telescopic hand tool is impacted by external force, it is likely to lead loosen or slip. Besides, when the user adjusts the length of the telescopic rod, an unexpected relative rotation between the inner tube and the outer tube of the telescopic rod might occur to cause deviation.

SUMMARY OF THE INVENTION

The primary object of the present invention is to provide a telescopic hand tool which enables to adjust its length in a stepless manner and is not easy to loosen or slip.

A telescopic hand tool comprises a telescopic rod. One end of the telescopic rod is provided with a working head, and another end of the telescopic rod is provided with a grip. The telescopic rod includes an inner rod and an outer tube slidably fitted on the inner rod. A circumferential side wall of the inner rod is formed with at least one rack gear along an axis. A circumferential side wall of the outer tube is formed with a positioning hole corresponding to the rack gear. A positioning member is provided in the positioning hole. The positioning member has a reciprocating movement along a central axis of the positioning hole. The positioning member has at least one toothed portion corresponding to the rack gear. The toothed portion has at least two engaging teeth. A control sleeve is slidably fitted on the outer tube. The control sleeve is slidable along the outer tube to form a locking position and an unlocking position. When in the locking position, the control sleeve presses the positioning member so that the toothed portion is engaged with the rack gear. When in the unlocking position, the control sleeve releases the positioning member so that the toothed portion is disengaged from the rack gear.

In the telescopic hand tool provided by the present invention, when the user adjusts the length of the telescopic rod to allow a relative sliding motion between the inner rod and the outer tube, the toothed portion of the positioning member can be adjusted to mesh with a corresponding meshing point on the rack gear to position the inner rod and the outer tube. Thus, the length of the telescopic rod can be adjusted in a stepless manner Because the toothed portions each have at least two engaging teeth, the contact area and positioning strength between the toothed portions and the two teeth can be improved greatly, so it is not easily affected by external force to avoid loosen or slip.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG.1is a perspective view in accordance with a preferred embodiment of the present invention.FIG.2is an exploded view in accordance with the preferred embodiment of the present invention. The present invention disclosures a telescopic hand tool100. The telescopic hand tool100comprises a telescopic rod10. One end of the telescopic rod10is provided with a working head20, and the other end of the telescopic rod10is provided with a grip30. In this embodiment, the telescopic rod10includes an inner rod11and an outer tube12. One end of the inner rod11is connected to the working head20, and the other end of the inner rod11forms a free end111. One end of the outer tube12forms an open end121. The free end111of the inner rod11is inserted through the open end121into the outer tube12and can be slid back and forth relative to the outer tube12. The other end of the outer tube12is provided with the grip30. Thus, the distance between the working head20and the grip portion30can be adjusted by adjusting the length of the telescopic rod10. It is worth mentioning that the positions of the working head20and the gripping portion30can be exchanged, that is, the working head20is disposed on the outer tube12, and the grip portion30is disposed on the inner rod11.

FIG.3is a cross-sectional view in accordance with the preferred embodiment of the present invention.FIG.4is a perspective view of a positioning member in accordance with the preferred embodiment of the present invention. Referring toFIG.2, a circumferential side wall of the inner rod11is formed with a guide groove112extending along an axis A, and two sides of the guide groove112are disposed with a rack gear113separately. A circumferential side wall of the outer tube12is formed with a positioning hole122corresponding to the two rack gears113. The positioning hole122is provided with a positioning member40. The positioning member40has a degree of freedom of reciprocating movement along a central axis B of the positioning hole122. The axial direction of the central axis B is perpendicular to the axis A. The positioning member40has a base41corresponding in shape to the positioning hole122. The base41has a first side surface411facing the inner rod11and a second side surface412opposite to the first side surface411. The first side surface411is provided with a guide slider42corresponding to the guide groove112. The guide slider42is slidable in the guide groove112. Two ends of the guide slider42are formed with arc-shaped surfaces421, so that the guide slider42slides more smoothly in the guide groove112. Two sides of the guide slider42are separately provided with a toothed portion43corresponding to the rack gears113. The toothed portions43each have at least two engaging teeth431to be engaged with the two rack gears113. The second side surface412is provided with a bearing portion44. In this embodiment, the number of the rack gears113and the toothed portions43are not limited thereto. In principle, the circumferential side wall of the inner rod11is provided with the at least one rack gear113, and the positioning member40is provided with the at least one toothed portion43to achieve the purpose of the present invention.

FIG.5is a cross-sectional view taken along line5-5ofFIG.3.FIG.6is a schematic view of the preferred embodiment of the present invention when in use. The telescopic hand tool100further includes a control sleeve50that is disposed on an outer periphery of the outer tube12and surrounds the positioning member40. The control sleeve50has a first end51facing the working head20and a second end52opposite to the first end51. A reduced portion53is defined on an inner wall of the control sleeve50adjacent to the second end52. One side of the reduced portion53is adjacently connected to an enlarged portion54. An inner diameter of the enlarged portion54is greater than an inner diameter of the reduced portion53. The control sleeve50is slidable along the outer tube12to form a locking position as shown inFIG.5and an unlocking position as shown inFIG.6. When the control sleeve50is in the locking position, the bearing portion44of the positioning member40is restricted by the control sleeve50and is pressed against the reduced portion53, so that the toothed portions43are engaged with the rack gears113. At this time, the inner rod11is unable to slide relative to the outer tube12. When the control sleeve50is in the unlocking position, the bearing portion44is disengaged from the reduced portion53to be in the enlarged portion54of the control sleeve50, so as to release the positioning member40. Therefore, the positioning member40regains the degree of freedom of reciprocating movement along the central axis B of the positioning hole122, so that the toothed portions43are disengaged from the rack gears113. At this time, the inner rod11is able to slide relative to the outer tube12.

When the user intends to adjust the length of the telescopic hand tool100, the user merely pushes the control sleeve50to move from the locking position to the unlocking position and then pulls the inner rod11to adjust the relative position between the inner rod11and the outer tube12. At this time, the positioning member40regains the degree of freedom of reciprocating movement along the central axis B of the positioning hole122, the toothed portions43are disengaged from the rack gears113in response to the adjustment of the telescopic rod10, and then the toothed portion43enables to select a corresponding meshing point with the rack gears113. After that, the user pushes the control sleeve50back to the locking position, so that the toothed portions43are engaged with the rack gears113, and the inner rod11and the outer tube12are positioned. In this way, the length of the telescopic rod10can be adjusted in a stepless manner Because the toothed portions43each have at least two engaging teeth431, the contact area and positioning strength between the toothed portions43and the rack gears113can be improved greatly, so it is not easily affected by external force to avoid loosen or slip. On the other hand, when the user adjusts the relative position between the inner rod11and the outer tube12, the guide slider42slides along the guide groove112to ensure that there is no relative rotation between the inner rod11and the outer tube12.

Referring toFIG.5, one side of the base41, facing the working head20, has a first restricting edge413, and the other side of the base41, facing the grip30, has a second restricting edge414. When the control sleeve50is either in the locking position or in the unlocking position, the first restricting edge413and the second restricting edge414are continuously restricted by an inner peripheral wall of the positioning hole122, so that the bearing portion44of the positioning member40continuously faces the inner wall of the control sleeve50, and the toothed portions43continuously face the rack gears113. Failure for actuation due to incorrect alignment between the control sleeve50, the bearing portion44and the toothed portion43is avoidable.

When the telescopic hand tool100is to be assembled, the assembly technician may attach the positioning member40onto the inner rod11. At this time, because the toothed portions43are engaged with the rack gears113to form a teeth engagement after assembly, thus the positioning member40is not likely to drop. Compared with the conventional steel ball structure, the telescopic hand tool100provided by the present invention has a better positioning effect for assembly. The guide slider42of the positioning member40is located in the guide groove112when assembled, which prevents the positioning member40from dropping.

Referring toFIG.5andFIG.6, the first end51of the control sleeve50extends beyond the open end121of the outer tube12and has a stop portion55. An elastic member60fitted on the inner rod11is provided between the stop portion55and the open end121of the outer tube12. The elastic member60provides an elastic force to push the control sleeve50, so that the control sleeve50has a tendency to move toward the locking position. Thus, after adjusting the length of the telescopic rod10, as long as the control sleeve50is released by the user, the control sleeve50is pushed back to the locking position by the elastic member60. It is convenient for operation. On the other hand, the inner diameter of the reduced portion53is greater than the outer diameter of the outer tube12, so that an annular space S is formed between the reduced portion53and the outer tube12. The telescopic hand tool100further includes a restricting ring70. The restricting ring70has a ring wall71located at the second end52. The restricting ring70has at least one blocking wall72corresponding to the annular space S. The blocking wall72is inserted in the annular space S. In this embodiment, the reduced portion53has a mating groove531. The blocking wall72has a mating block721corresponding to the mating groove531. The mating block721is mated with the mating groove531, so as to secure the restricting ring70to the second end52of the control sleeve50. Thereby, the blocking wall72blocks the protrusion44of the positioning member40to prevent the control sleeve50from slipping off the outer tube12.

FIG.7is a cross-sectional view taken along line7-7ofFIG.3. The base41is slightly smaller than the positioning hole122, so that a gap D is defined between the base41and the inner peripheral wall of the positioning hole122. The positioning member40further has a degree of freedom of translational movement relative to the outer tube12. When the user adjusts the relative position between the inner rod11and the outer tube12for the positioning member40to bounce in the positioning hole122to select a desired meshing point, a certain tolerance can be kept to ensure that the toothed portions43of the positioning member40to be engaged with the teeth113. It is worth mentioning that the inner rod11is a round rod, and the second side surface412forms an arc surface corresponding to the surface of the inner rod11, so that the positioning member40is close to the curvature of the inner rod11.