FLEXIBLE JOINT

The present application relates to a joint for transferring rotating movements. The joint has a general application, but is particularly applicable in tools admitting access to corners or other difficult locations with e.g. a drill bit, cutter, socket wrench, bits or the like.

In particular electricians often need to drill holes in corners. This may be difficult in itself, but in particular if there is a narrow access to the corner. It has been developed particular battery powered drilling machines (hand drills) where the mounting for the drill bit is located at the extremity of the tool body. However, this is a rather bulky tool which cannot reach completely into the intersecting line between two perpendicular planes, and which may be too long to reach into a tight place.

US patent 3,064,543 describes a tool with an input and output shaft connected with a universal joint of an approximately Cardan type. The input shaft may be mounted in an electrical drill, while a chuck is mounted on the output shaft. It is said that it may be used with a quite large angle between the drill machine and drill bit, but both the universal joint and chuck occupy much space preventing the use of the tool fully into corners.

International patent application WO 03/026822 describes a somewhat similar tool. The tool includes an input shaft mounted in an electrical drill, a universal joint and an output shaft. The output shaft includes a bit mount for holding drill bits. The tool is meant to be used in the aircraft industry, for drilling holes precisely perpendicular on the work surface. For this means, the tool is equipped with a pilot bushing or jig. This pilot bushing prevents the tool accessing tight places, which neither is the object of the tool. Further, the tool is equipped with a Cardan type universal joint, which only can transfer an even rotation when the two shafts are aligned. There is nothing preventing the occurrence of large angles between the shafts leading to the joint becoming locked.

An object of the present invention is to provide a joint which is small and flexible, as well as a tool using said joint providing the user with the possibility of accessing tight places.

This is solved with a joint and tool as defined in the appended claims.

The invention will now be described in reference to the appended drawings, in which:

Fig. 1 is a perspective view of the inventive tool,

Fig. 2 shows a longitudinal section through a joint which is part of the tool,

Fig. 3 shows a corresponding cross section through the joint shown in Fig. 2.

The tool shown in Fig. 1 comprises an input shaft 3 intended to be fastened in the chuck of an electric drill. The input shaft 3 is connected to an output shaft 2 via a joint 5. The output shaft 2 has a mount 6 in the end. The mount 6 is smaller than a common chuck, and allows the tool to be taken fully into a corner. The mount 6 may consist of a boring with one or more mounting screws intended to hold the stem of a drill bit, adapter or the like. The mount 6 may also be formed as a hexagonal bit mount intended for standard Vi" tool tang or adapters, possibly with holding means such as clips, catches or magnets.

In use the drilling machine is fastened at the end of the input shaft 3, while a tool such as a drill bit is mounted in the end of the output shaft 2. Due to the joint 5, the output shaft 2 may now be placed fully into the angle between two walls allowing the drill bit to come fully into the corner. When the drill machine is driven, the joint 5 will transfer the turning movement to the drill bit.

The joint 5 is shown in Fig. 2. The joint 5 consists of a part 7 formed as a bushing and which is mounted on the input shaft 3. Inside the bushing 7 there is a polygonal rounded part 8 which is mounted on the output shaft 2. The polygonal part may be designed as a hexagonal rounded body as shown in the illustration. The part 8 catches corresponding edges within the bushing 7. The part 8 is pivotably mounted in the bushing with a pin 1. To allow the part 8 to turn in several directions, the through hole 9 in the part 8 is given a double cone shape. The hole may also be flat; only being double cone in one dimension. The cone shape of the hole will also restrict the angular deflection of the joint; i.e. it may not be deflected so much that it becomes locked. The joint may also be equipped with a rubber sleeve or bellow sealing the connection between the bushing 7 and the output shaft 2. This allows the placement of a small lump of grease within the joint.

Fig. 3a and b show the joint in cross section. The inner bal- shaped part 8 catches surfaces formed on the inside of the outer bushing 7. The surfaces may be straight as shown in the figure. Optionally the surfaces may be weakly convex, with rounded

comers, in order to increase the contact surface against the corners of the ball 8. The embodiment of Fig. 3 a has a hole which is conical in only one direction.

While the shaft 3 here is called the input shaft, and the shaft 2 is called the output shaft, there is of course nothing preventing the two shafts from interchanging their function, i.e. that the shaft 2 is used as an input shaft and the shaft 3 is used as an output shaft.