Tool Adaptor

Field of Invention

The present invention relates to a tool adaptor. Particularly the invention relates to tool adaptor capable of attaching with any drive mechanism, for combining a manual wrenching operation with a power assist while allowing bolt/stud lengths to pass through the driving head. The invention has particular application in a power tool, which may be used for fastener applications, or anywhere that rotary motion is required.

Background Many drills and fastener power tools in the market rely solely on the power delivery from the motor and transmission system. When tasks fall outside this range the tool becomes ineffective. By providing these tools with a manual ability it is possible to increase their operating range.

When using socket wrenches for fastener operations, interference is often experienced between the protruding bolt/stud length and the socket being used, as the nut is tightened. Likewise nuts may become beyond the reach of the socket if the protruding bolt/stud length is longer than the socket in use.

Summary of Invention

The present invention combines a reversible socket wrench with an electric motor and transmission, which can either be used as a power driven tool or a manual wrench. The driving head of the tool incorporates a compound clutch which enables the tool to be used in a manual or power driven manner without the risk of drive conflict. The driving head and components are hollow to allow bolt/stud lengths to pass through without interference.

It was decided that the best way to ensure drive conflict does not occur would be to incorporate the direction change into the mechanical driving head of the tool. By doing this there is no need for an electrical change switch at the controller and the drive condition can be set with a single operation.

Brief description of Drawings

Figure 1 is a profile view of the tool layout

Figure 2 is a view of the twin clutch arrangement

Figure 3 is a section view of the drive head mechanism Figure 4 is another view of the twin clutch arrangement Figure 5 is a view of gear driven clutches Figure 6 is the tool holder

Description of the invention

A preferred embodiment of the invention is disclosed in figures 1 to 3 of the accompanying drawings. Before describing the preferred embodiment, a general description the of the invention and its working mechanism is given below:

The invention combines the features of a low profile drill with the wrenching ability of a manual wrench, by integrating a chrome vanadium steel wrench chassis. The design gives a manual ability for high torque applications beyond the range of the drive system. The tooling allows stud lengths to pass through the hollow driving head for nut running operations. A multi-speed planetary gear system enables the motor to deliver maximum torque for wrenching operations, or maximum speed for drilling. The drive direction is determined by mechanically adjusting the height of the drive anvil assembly, which consequently engages the clockwise/anti-clockwise bevel gears eliminating the need for an electrical direction change within the motor. The two one-way clutches located in the lower mounting plate of the drive head sub-assembly, are used to transfer manual torque from the chassis to the drive anvil as with conventional wrenches. These will share roller bearings and the in use will be dependant upon the position of the drive anvil. This system removes the potential of drive conflict between the mechanical systems and the motor drive direction.

The compound friction clutch within the driving head is composed of four frictional clutches which engage within a minimal arc. They are silent running and are designed to work without conflict between the manual or power assisted operations. The layout of the drive ensures only two of these clutches operate for each drive direction, but only one will engage at any time, resulting in no additional operations being required to switch between manual or drive assist.

The clutches within the mounting plate are designed to deliver manual torque to the hollow drive anvil, but free-wheel if the drive is supplied from the motor transmission through the gear driven clutches. Likewise the gear driven clutches are designed to engage drive to the hollow drive anvil from the motor transmission but free-wheel if manual torque is applied. The tool holder will be incorporated directly into the design of the drive anvil as a single part providing a receptacle for a compatible range of tooling, which will allow stud lengths of up to 24mm diameter to pass though the driving head. In addition to this tooling, adaptors will be developed to enable the use of conventional tooling (i.e. socket sets) and a keyless chuck for drilling applications. Because the design allows the passage of the stud length through the driving head, conventional square drives common in socket wrenches will be replaced by an external spline drive. The specially developed adaptors will ensure compatibility with conventional tooling and are located within the spline, held in place using a sprung steel retaining ball.

The body is composed of two half-shells in which the motor and transmission are secured to the wrench chassis in an under slung manner. The transmission has an output shaft which drives a pinion in the driving head to transfer the non-parallel intersecting drive to the drive anvil through a compound set of gears and clutches. This part of the invention includes a detachable battery set which is received in the body and connects directly to the speed controller which drives the motor. The transmission is made up of a planetary gear set incorporating two speeds. An adjustable torque slip clutch makes use of the multiple degrees of freedom within the gear set to release the drive at set torque values.

Due to the cordless nature of this tool, the use of a battery pack would be the most cost effective and viable option. It has been decided that Nickel based cells would be used within this product. The cell type that provides the desired performance characteristics for this application is a 4/5 subC. The 14.4V NiMH Battery pack will be arranged in a face centred (nested) manner to form a multi-row cell pack. This arrangement takes up minimum space and the cells will be connected in series, using nickel foil strip welded across the terminals. The pack will be finished with a connector and heat shrink wrap before being inserted into the battery.

Pulse Width Modulation technique is used to control the motor speed within the wrench by adjusting the duty cycle to the DC motor. This method supplies voltage to the motor at a fixed value, which improves the torque potential as the motor is subject to full voltage across its

terminals whenever the power is on. AU the electronics will be contained in the trigger unit, where the variable speed output is controlled with compression on the trigger, adjusting a potentiometer which varies the output from a pulse width modulator (PWM). Details of the electrical layout can be seen in figure 9.

Detailed Description of Preferred Embodiment

Referring to Figures 1 to 3, an electric drill/wrench in accordance with the present invention comprises of a body (41), a wrench chassis (1), a handle (34), a battery pack (35, 37), a controller (42), a motor (22), a planetary gear box (11), a torque release planetary transmission (2), a gear change lever (30), a gear selector (39), a torque dial (33), a clutch retaining plate (31), a driveshaft (6), a pinion (32), a drive anvil (43) with integrated tool retaining device (46), two gear driven clutches (52) with rollers (51) and compression plate (50), two clutches (48) mounted in a base plate (47), a change switch (55) and spring (56), a drive retaining device (54) and washer (53).

The body (41) comprises of two half shells which could be secured by fasteners such as screws. The body makes up the housing for the motor (22) and transmission (11 , 2). It attaches rigidly to the wrench chassis (1) again using fasteners.

The wrench chassis (1) is formed to give strength and deliver manual torque from the handle (34) to the driving head of the tool. The driving head of the wrench chassis (1) receives the drive anvil assembly as seen in figure 7. The motor (22) and transmission (11,2) is received by the body (41) and held by the internal architecture of the body (41) or optionally between inner liners. The driveshaft (6) passes into the driving head through the wrench chassis (1) where it drives a pinion (32). In the proposed embodiment the transmission comprises of a two speed planetary gear box (11) and a torque release planetary transmission (2). In the proposed embodiment rechargeable battery pack (35, 37) is detachable and is received in the body (41) where it electrically connects to the controller (42) which adjusts the motor (22) speed.

The drive anvil (43) is hollow to allow bolt/stud lengths to pass through the driving head of the tool. The proposed embodiment incorporates a tooling retaining device (46).

The gear driven clutches (52) deliver drive from the non-parallel intersecting pinion (32) to the drive anvil. In the proposed embodiment roller clutches comprising of rollers (51) and a compression plate (50) are used to transfer the drive using the static friction within the clutch.

The base plate (47) within the embodiment incorporates two clutches (48) to transmit the manual torque to the drive anvil from the wrench chassis (1). In the proposed embodiment roller clutches comprising of rollers and a compression plate are used to transfer the drive using the static friction within the clutch.

The change switch (55) is spring (56) loaded and used to adjust the height of the drive anvil (43) and attached components. This height adjustment switches the drive direction by engaging the relevant gear driven clutch (52) and clutch (48). The whole drive head assembly is constrained using the washer (53) and retaining device (54).