The present invention relates to a hand tool having an adjustable head with a joint lock mechanism, especially a hand tool with an adjustable angle head and easier, more secure positioning.

Conventional hand tools with an adjustable head, for example, as disclosed in TW421111, corresponding to US6,295,898, and TW488349, comprise a head and a handle. The head has a convex portion which can be pivotally coupled to a concave portion of the handle. Teeth are disposed along the surface of the convex portion to engage a ball received in an aperture formed in an inner wall of the concave portion. A stop member is disposed between the head and the handle. A positioning portion is formed at a rear side of the stop member and is coupled to a front end of the handle. A toothed portion formed at a front side of the stop member is engageable with a toothed surface portion formed along the surface of one side of the convex portion. When the stop member is slid to a predetermined position, the adjustment and positioning of the head at a certain angle can be more securely and conveniently done. However, with this kind of wrench, the ball is of a circular shape and cannot ensure secure engagement, and similar to the configuration of a ball and a toothed portion of a convex portion, the toothed portion of the stop member and the toothed surface portion of the handle may be worn out after use for a long period, which can therefore cause inconvenience when in use and reduce the life time of the hand tool.

TW478444 has disclosed a wrench wherein a through hole is formed in the centre of a shaft and threads are formed on a wall of the through hole at a bottom of the shaft to receive an operation rod. A handle is mounted at a bottom end of the operation rod and rotates synchronously with the operation rod. A concave portion formed at a top end of the shaft is coupled to a head and secured by a screw. A retainer is received in the through hole of the shaft with its one end coupled to the top end of the operation rod and an arc shaped concave portion formed on the other end. A rotatable worm supported by a retainer is disposed in the concave portion of the shaft and a groove fitted with a clip is formed at a protrusion of the worm at one end. A worm gear is disposed at an extension end of the head and engages the worm. The other end of the worm is coupled to a pivotal block and a crane to actuate the worm gear and the worm such that the head can be rotated at any angle. Again, with this configuration, the worm and the worm gear may be worn out after use for a long period, which causes the local structure to be loose and unable to be positioned properly. In addition, it is likely that the clip, operation rod, the retainer or the pivotal block and the crane might become loose and make the wrench un-useable.

EP-A-0 377 777, GB-A-273,914 and US 2001/ 0000092 A1 disclose spanners with adjustable angle heads locked and unlocked by a button actuating an engaging mechanism.

From the above, it is necessary for the industry to provide a hand tool having an adjustable head with a joint lock mechanism, which offers convenient and secure angle adjustment and positioning and can overcome the defects mentioned in the prior art.

US-B1-6,405,621 discloses a hand tool with an adjustable angle head, on which the pre-characterizing portion of claim 1 is based.

It is an object of the present invention to provide a hand tool having an adjustable head with a joint lock mechanism, easier and more secure positioning.

The present invention provides a hand tool as defined in claim 1.

The invention will be described by way of example with reference to the accompanying drawings, in which:

• Fig. 1 illustrates an exploded view of a handle tool having an adjustable head with a joint lock mechanism according to the present invention;
• Fig. 2 illustrates a locally enlarged plan view thereof;
• Fig. 3 illustrates a sectional view thereof along line A-A in Fig. 2 showing a pull button in a locked state;
• Fig. 4 illustrates a sectional view thereof along line A-A in Fig. 2 showing the pull button in an unlocked state;
• Fig. 5 illustrates a locally enlarged side view thereof;
• Fig. 6 illustrates a sectional view thereof along line B-B in Fig. 5 showing the pull button in a locked state;
• Fig. 7 illustrates a sectional view thereof along line B-B in Fig. 5 showing the pull button in an unlocked state;
• Fig. 8 illustrates a sectional view thereof along line A-A in Fig. 2 showing the head inclining 0° with respect to a handle;
• Fig. 9 illustrates a sectional view thereof along line A-A in Fig. 2 showing the head inclining 11.25° with respect to the handle;
• Fig. 10 illustrates a sectional view thereof along line A-A in Fig. 2 showing the head inclining 25° with respect to the handle;
• Fig. 11 illustrates the head rotating at multiple angles; and
• Fig. 12 illustrates a different pattern formed on the pull button.

Fig. 1 illustrates an exploded view of a handle tool having an adjustable head with a joint lock mechanism according to the present invention. A wrench 10 comprises a head 20, a handle 30 and a joint lock mechanism 40. A convex portion 21 is formed at a rear end of the head 20 and a through hole 22 is formed through the convex portion 21. A concave portion 31 is formed at a front end of the handle 30 and two through apertures 32 are formed at opposite sides thereof where one of the through apertures 32 is threaded to receive a screw 24 for pivotally coupling the head 20 to the handle 30. A first aperture 33 is formed at the front end of the handle 30 and substantially extends along the length thereof, and a second aperture 34 is formed at one side of the handle 30 and perpendicularly intersects the first aperture 33.

A joint lock mechanism 40 comprises a first engaging device disposed at the rear end of the head 20, a second engaging device received in the first aperture 33 formed at the front end of the handle 30, a first elastic device and a pull button 45 comprising a knob portion 451 and an engaging portion. The first engaging device has a plurality of slots 23 formed equidistantly along the surface of the convex portion 21 and the slots 23 preferably extend parallel to the axis of the through hole 22. In general, the surface of the convex portion 21 can be an arc of 180°, or of any other suitable shape. In this preferred embodiment, nine slots are formed so that the angle between two adjacent slots is 22.5°. Preferably, the second engaging device is a pin 42 and the first elastic device is a first spring 41. An engaging portion, which is a protrusion 43 of a substantially arc shape, is formed at a front end of the pin 42. As illustrated in Fig. 3, the first spring 41 is received at and abuts a bottom end of the first aperture 33 and biases the pin 42 with a forward force such that the protrusion 43 of the pin 42 can be pushed to engage any of the slots 23. A pair of slots 44 is formed at the opposite sides of the pin 42 between the front and the rear ends of the pin 42. The engaging portion of the pull button 45 comprises two hooks 452 disposed beneath the knob portion 451 and extending along the second aperture 34 to engage the corresponding pair of slots 44 such that the pull button 45 can be pulled to actuate the pin 42 to move along the first aperture 33. The knob portion 451 can be of a shield design formed with a plurality of anti-slip teeth thereon or with a pattern consisting of a word "LOCK", a side-view mark of the head and a double arrow crossing the side-view mark (referring to Fig. 12). Alternatively, the pin 42 can be formed with a through slot between the front and the rear ends thereof (not shown in figure) and the engaging portion of the pull button 45 can be a hook extending along the second aperture 34 to engage the through slot (not shown in figure) such that the pull button 45 can be pulled to actuate the pin 45 to move along the first aperture 33.

The joint lock mechanism 40 further comprises a positioning device 50 having a positioning element, preferably a positioning plate 51, and a second elastic device, preferably a second spring 52. The positioning plate 51 is received in a front portion 331 of the first aperture 33 having a larger diameter (referring to Fig. 3), which can be formed by reaming a stepped aperture at the front end of the first aperture 33, while a rear portion 332 thereof has a smaller diameter (referring to Fig. 3). A pair of slots 46 is disposed at the front end of the pin 42 and the positioning plate 51 is received in the slots 46. The positioning plate 51 has a shape substantially matching that of the protrusion 43 so as to guide the protrusion 43 to engage one of the plurality of slots 23. The second spring 52 is positioned behind the positioning plate 51 with its front end abutting the positioning plate 51 with a forward force and its rear end abutting a shoulder portion 333 formed between the front portion 331 and the rear portion 332, such that protrusions 53 of the positioning plate 51 and the protrusion 43 of the pin 42 can together engage one of the plurality of slots 23.

Figs. 2 and 5 illustrate a locally enlarged plan view and a locally enlarged side view of the hand tool according to the present invention, respectively. From Figs. 3 and 6, it can be seen that when the pull button 45 is in a locked state, each of the protrusion 43 of the pin 42 and the protrusions 53 of the positioning plate 51 can moveably engage one of the plurality of slots 23, whereas only the protrusions 53 of the positioning plate 51 can moveably engage one of the plurality of slots 23 when the pull button 45 is in an unlocked state. Therefore, when the pin 42 disengages the head 20 in the unlock state, the head 20 can pivotally rotate with respect to the handle 30 and also be prevented from rotating due to gravity. As illustrated in Figs. 8 to 10, when an external force drives the head 20 to a certain angle, the head 20 can be bent and positioned to a predetermined angle. Fig. 11 illustrates the head rotating to multiple angles.

From the above descriptions, it is apparent that the present invention provides a hand tool having an adjustable head with a joint lock mechanism and has easier and more secure positioning over the prior art. While the invention has been described in terms of several preferred embodiments, those skilled in the art will recognise that the invention can still be practiced with modifications, within the scope of the appended claims.