Patent Description:
The manufacturing and application of power tools such as pistol tools has certain challenges especially in industrial environments such as for example assembly factories. Such factories typically have electromagnetic compatibility (EMC) and electrostatic discharge (ESD) standards that need to be followed and fulfilled. If they are not fulfilled problems with workers, for instance workers who have a pacemaker, or problems with sensitive equipment in general and sensitive assembly components can occur. In view of these EMC and ESD standards, power tools are today grounded via a cable if they are cable connected tools or they are grounded when connected to a controller that is close to the assembly area, which controller has ground level and therewith provides the same ground level to the tool. One issue that thereby occurs is that the tools or power tools do not have the same ground level across the entire tool due to the extensive use of plastic materials in the actual tool, which plastic electrically isolates several parts, such as for example the motor and the battery adapter, from one another leading to different ground levels in one and the same tool. Especially the handle part of the tool is widely made of plastic and therewith the motor unit and the battery adapter and the battery do not have the same ground level, which leads to problems with EMC and ESD standards since it is not entirely sure what kind of ground level the different parts of the tool have. One solution for this has been to introduce two metal plates into the shell of the handle on both inner sides of it, whereby the metal plates extend from the battery adapter to the motor unit. These metal plates are however cumbersome to install since they need to be bent at the edges and otherwise adapted and they are also difficult to assemble when the tool is produced and therewith make the tool expensive due the following:
Up to today the printed circuit boards (PCB), the controller, the buttons in particular the control button that controls the tool, the cables, the antennas and other components are pressed into one of two handle-shells and then the other handle shell is just pressed onto the first handle shell and screwed tight. The handle shells are typically left and right handle shells. One can imagine that this leads to quite some challenges and uncertainty as to where the actual components are placed once the handle is closed. These challenges are further increased when each handle shell needs to house a metal plate for providing the same ground level across the entire tool. In addition, it is cumbersome and expensive to provide metal plates that fit into the handle shells and do not destroy any other components such as cables or antennas. The assembly of the components within one shell of the handle makes it also very difficult to repair the power tool and replace components. Usually, the entire handle has to be disassembled, the component replaced and then the handle reassembled, which takes time and therewith leads to long down times of such power tools or pistol tools.

Another shortcoming with prior art power tools is that the connection or interface between handle and battery adapter and battery, respectively is rather rigid and stiff. When the power tool thus gets an impact, for example due to falling to the ground, it tends to break at the interface or intersection battery adapter and battery, respectively, and handle.

<CIT>, disclosing the preamble of claim <NUM>, <CIT>, <CIT>, <CIT> and <CIT> disclose examples of prior art power tools.

An object of the present invention is therefore to provide an improved power tool.

Another object of the present invention is to provide a power tool such as a pistol tool that is reliable, robust and easy to assemble.

The inventor of the present invention has discovered that the above-described challenges and problems with prior art power tools such as pistol tools can be overcome by providing a power tool having a battery unit, a handle unit and a motor unit, whereby the handle unit comprises a frame that interconnects the battery unit with the motor unit. The frame is thereby made of an electrically conductive material that is strong and robust, such as for example aluminum or conductive fibre, such as metal fibre, reinforced plastic. The advantage of such as solution is that the PCBs, the controller, the cables, the antenna, the communication unit and other components can be assembled to the frame and not into a handle shell. This leads to a cleanly assembled power tool that has the same ground level over the entire tool. By providing an adapter between the frame and the battery unit, which adapter is capable of absorbing shocks and impacts, whereby the adapter is also made of an electrically conductive material such as aluminum, steel or metal fibre, reinforced plastic, it is further possible to make the power tool resistant to destruction at the handle - battery unit interface. The inventor has further realized that this resistance to destruction can further be increased when inner handle covers and outer handle covers with different amounts of glass fibres embedded in plastic are provided, whereby the inner handle covers are made less stiff than the outer handle covers.

Disclosed herein is a power tool for example a pistol tool or any other hand held power tool comprising a motor unit comprising a motor and a drive axle connected to the motor, a battery unit configured to receive a battery and a handle unit interconnecting the motor unit and the battery unit, the handle unit comprising:.

wherein the frame is made of an electrically conductive material, and wherein the handle unit further comprises an adapter that is connected to the frame and the battery unit, whereby the adapter is electrically conductive and designed to have shock absorbing capabilities.

In such an embodiment the frame provides a basis for the mounting of all other components in the handle and at the same time the frame provides one and the same ground level across the entire tool from the motor unit to the battery unit and the battery when the battery is coupled. Thus the frame serves as mounting platform for the other components in the handle unit.

Since the frame provides the basis for mounting the components one of the outer handle cover can be removed and all the components stay cleanly and neatly in place, which facilitates maintenance and repair of the pistol tool.

In an embodiment the frame may be made of a metal such as aluminium, steel or titan or of an electrically conductive fibre reinforced plastic.

All of these materials are electrically conductive and therefore they enable the grounding of the entire power tool.

According to the invention, the handle unit comprises an adapter that is connected to the frame and the battery unit, whereby the adapter is electrically conductive and designed to have shock absorbing capabilities.

The adapter may be integrally formed with the frame or the battery unit or both. The adapter helps to reduce the risk of a pistol tool breaking at the interface handle unit - battery unit in case of a fall for instance.

In an embodiment the adapter may also be made of a metal such as aluminium, steel or titan or electrically conductive fibre reinforced plastic.

This helps that the conductivity is established from motor unit to the battery unit.

In another embodiment the adapter may comprise a longitudinal web and at least one arch-shaped element connected to the longitudinal web and the adapter may comprise an electrically conductive adapter - battery unit fastening mechanism and an electrically conductive adapter - frame fastening mechanism.

The above design of the adapter helps to improve the shock absorbing properties of the adapter and ensures a good and reliable connection to the handle unit and the battery unit, respectively.

The adapter may comprise two arch-shaped elements and one web or two webs and two arch-shaped elements for improved stability and reliability.

In an embodiment the frame may comprise a frame - motor unit fastening mechanism and a frame - adapter fastening mechanism, wherein the frame - motor unit fastening mechanism and the frame - adapter fastening mechanism are electrically conductive, said mechanisms being used for connecting the frame to the motor unit and the adapter and therewith the battery unit.

These fastening mechanisms provide a reliable and strong connection between handle unit and motor unit and handle unit and battery unit and adapter, respectively. At the same time the fastening mechanisms are electrically conductive for providing one and the same ground level across the entire pistol tool.

In an embodiment the handle unit further may further comprise a pair of inner handle covers configured to be arranged around the frame and printed circuit board and configured to be arranged on an inner side of the pair of outer handle covers.

The pair of inner handle covers are made of glass fibre reinforced plastic comprising <NUM>% to <NUM>% by weight glass fibres and wherein the pair of outer handle covers are made of glass fibre reinforced plastic comprising <NUM>% to <NUM>% by weight glass fibres.

The pair of inner handle covers may further improve the shock resistance of the pistol tool. In particular if the amount of glass fibres is chosen to be less in percentage by weight as in the pair of outer handle covers, then the distribution of the shock or load is improved in case of an impact, since the pair of inner handle covers are allowed to be deformed with less force or shock than the pair of outer handle covers which leads to an optimized load distribution and therewith a higher shock resistance.

In an embodiment the frame may further comprise a bolt opening configured to receive a bolt for fastening the printed circuit board and the pair of inner handle covers, the bolt being made of electrically conductive material and configured to physically touch the printed circuit board.

The bold may be advantageous for a clean and robust assembly at the same time it may provide grounding to the printed circuit board. This grounding may alternatively be provided via an electrically conductive sleeve that is arranged around the bolt.

In an embodiment at least one of the pair of inner handle covers comprises a channel for receiving and embedding cables.

This will lead to a better and safer arrangement of the cables and therewith to a more durable pistol tool.

In an embodiment the frame may comprise a receiving cavity for mounting the control button.

Such a receiving cavity facilitates the replacement of the control button in case it breaks. The control button and its trigger, respectively, may be fastened via a splint or the like in a trigger adapter, which is embedded via a spring in the receiving cavity. Removing the splint will allow to easily replace the control button. Other solutions may of course be used but the receiving cavity also facilitates assembly of the control button.

In an embodiment the handle unit may further comprise an insulation and protection element that is connected to the frame in between the frame and the printed circuit board.

This insulation and protection element may be made of an electrically insulating and rather soft material so that it can protect the printed circuit board and other sensitive electric components from electric discharges or shocks or the like.

In an embodiment the outer handle cover may extend from the motor unit to the battery unit.

This provides for a stable covering of the handle unit.

Herein the term "electrically conductive and strong material" generally means either some type of metal such as aluminium, steel, titan or an alloy thereof or fibre reinforced plastic, whereby the fibres may be electrically conductive carbon fibres or metal fibres.

Herein the term "fastening mechanism" refers generally to thread, bolt, hole and screw combinations for fastening components to one another. Other fastening mechanisms such as form fit or force fit connections and even adhesive induced connections or electrically conductive adhesive induced connections are covered by this term.

The present invention will now be described, for exemplary purposes, in more detail by way of an embodiment(s) and with reference to the enclosed drawings, in which:.

<FIG> illustrates a pistol tool <NUM> having a motor unit <NUM>, handle unit <NUM> and a battery unit <NUM>. The pistol tool <NUM> is shown without a battery, it is however clear that a battery can be coupled to the battery unit <NUM>. The motor unit <NUM> comprises a motor housing <NUM> and a motor <NUM> (c. The motor <NUM> is driving a drive axle <NUM> (c. <FIG>) having a bit connector <NUM>. The handle unit <NUM> comprises a reverse button <NUM> to change the rotational direction of the motor and therewith the axle <NUM> and the bit connector <NUM>, respectively. Then handle unit <NUM> further comprises a control button <NUM> with a trigger <NUM> and a pair of outer handle covers <NUM> arranged to cover the handle unit <NUM>. The pair of outer handle covers <NUM> extend from the motor unit <NUM> to the battery unit <NUM> and are fastened to the motor unit <NUM> and the battery unit <NUM> via an outer handle cover fastening mechanism <NUM>, as shown in <FIG>. The outer handle cover fastening mechanism <NUM> comprises of a thread-hole, screw bolt and hole combination as illustrated in <FIG>.

Turning now to <FIG>, which shows the same pistol tool <NUM> as <FIG> but with removed front cap and bit adapter and also with a removed, left, outer handle cover <NUM>. The pair of outer handle covers <NUM> each comprise a reverse button recess <NUM> that extends through the outer handle covers <NUM>. The reverse button recess <NUM> is also formed in a frame <NUM> of the handle unit <NUM>, which frame <NUM> holds a printed circuit board (<FIG>) and other components as further explained herein. The frame <NUM> illustrated in <FIG> extends from the motor unit <NUM> down to the battery unit <NUM> and is made of an electrically conductive material to provide the same ground level across the entire pistol tool <NUM>. Illustrated is also the control button <NUM> with its trigger <NUM> that sits in a trigger adapter <NUM>. <FIG> further illustrates a pair of inner handle covers <NUM> of the handle unit <NUM>, at least one of the inner handle covers <NUM> of said pair of inner handle covers <NUM> comprising a cable channel <NUM> comprising cables <NUM> interconnecting the motor unit <NUM> with the handle unit <NUM> and its printed circuit board (c. <FIG>) and the battery unit <NUM>. The cables <NUM> further connect the antennas <NUM>, arranged on both sides of the handle unit <NUM> with the printed circuit board and controller (not shown in <FIG>). The battery unit <NUM> comprises battery receivers <NUM> for receiving a battery in a form-fit manner, for instance a slide and lock mechanism. As mentioned in the introductory part, the pair of outer handle covers <NUM> are made of <NUM>% to <NUM>% glass fibres, preferably <NUM>%, glass fibres embedded in plastic whereby the percentage relates to weight-percentages and the pair of inner handle covers <NUM> are made of <NUM>% to <NUM>%, preferably <NUM>%, glass fibre embedded plastic. This differing amount of glass fibre leads to an optimal distribution of load in case of shocks and impacts and/or deformations in the pistol tool <NUM>.

Turning now to <FIG>, which illustrates, in more detail, some additional features of the pistol tool <NUM> according to the invention. The frame <NUM> comprises a frame motor unit fastening mechanism <NUM> and a receiving cavity <NUM> for receiving the control button <NUM> with its trigger <NUM> and trigger adapter <NUM>. The frame motor unit fastening mechanism <NUM> comprises of an electrically conductive bolt, thread hole and hole combination. The trigger <NUM> is locked in the trigger adapter <NUM> via a splint <NUM>, which splint also makes it easier to replace the trigger <NUM> in case it is damaged. In the receiving cavity <NUM> a spring (not visible in <FIG>, c. <FIG>) is embedded that pushes the control button <NUM> away from the receiving cavity <NUM>. The frame <NUM> has an upper part that is wider than the width at the actual handle of the handle unit <NUM>. The frame <NUM> is further made of aluminum and is basically a spline or metal spline.

<FIG> further illustrates the inner handle cover <NUM>, whereby at least the left inner handle cover <NUM> comprises a cable channel <NUM> for, illustrated without cables inside in <FIG>, for receiving the cables hold them tidy in place during assembly and afterwards. The pair of inner handle covers <NUM> are fastened to the battery unit <NUM> via an inner handle cover fastening mechanism <NUM>, which again comprises a thread hole, bolt and hole combination. The thread holes of the outer handle cover fastening mechanism <NUM> is also visible in <FIG> as well as a bolt <NUM> for fastening the pair of inner handle covers <NUM> to the frame <NUM>. This bolt <NUM> also helps to keep the printed circuit board in position and connected to the frame <NUM>.

<FIG> illustrates the pair of inner handle covers <NUM> comprising a foot part <NUM> where the inner handle cover fastening mechanism <NUM> is located.

<FIG> illustrates the frame <NUM> of the handle unit <NUM> clearer since the pair of inner handle covers <NUM> are not shown. Mounted on the frame <NUM> is the printed circuit board <NUM> or circuit board <NUM> comprising various circuit <NUM> and a communication unit <NUM>. The circuit board <NUM> also comprises a computer processing unit (CPU) <NUM>, it is mounted to the frame <NUM> via the bolt <NUM> and it is connected to the battery unit <NUM> via cables <NUM>. The bolt <NUM> is also providing a grounding function since it electrically connects the frame <NUM> with the circuit board <NUM> via a sleeve <NUM>, as shown in <FIG>. In between the circuit board <NUM> and the frame <NUM> an insulation and protection element <NUM> (c. <FIG>) is arranged. The protection and insulation element <NUM> is made of rubber or another suitable material that electrically insulates the circuit board <NUM> from the frame <NUM> and the insulation and protection element <NUM> also works as cushion to protect the circuit board <NUM> from shocks and other physical impacts. The frame <NUM> is connected to the battery unit <NUM> via an adapter <NUM>, which is also illustrated in <FIG>. The adapter <NUM> is made of an electrically conductive material, such as metal like aluminum, titan or steel or plastic reinforced with electrically conductive fibers. The adapter <NUM> is designed as a shock absorbing element that can absorb shocks when the pistol tool <NUM> falls down or gets another impact via the battery unit <NUM> when the battery is connected. The frame <NUM> is connected to the adapter <NUM> via an adapter-frame fastening mechanism <NUM> and the adapter <NUM> is connected to the battery unit <NUM> via an adapter-battery unit fastening mechanism <NUM>.

The adapter <NUM> is connected to the battery unit <NUM> via a battery unit housing <NUM>.

<FIG> illustrates the adapter <NUM> in more detail. The adapter <NUM> comprises a longitudinal web <NUM> and two arch shaped elements <NUM>. The arch shaped elements <NUM> are integrally connected to the web <NUM>. On the sides where the arch shaped elements <NUM> are not connected to the web <NUM> they comprise feet <NUM> that ease the mounting of the adapter <NUM> and increase stability when the adapter <NUM> is mounted. On the highest point of the arch shaped elements <NUM> the holes of the adapter-frame fastening mechanism <NUM> are shown, said holes being designed for receiving a screw or bolt of the adapter-frame fastening mechanism <NUM>. On one end of the web <NUM> a hole of the adapter-battery unit fastening mechanism <NUM> is shown, said hole being for receiving a screw or bolt of the adapter-battery unit fastening mechanism <NUM>. The other hole of the adapter-battery unit fastening mechanism <NUM> is shown on one of the feet <NUM> of the arch shaped element <NUM>. <FIG> shows an exemplary embodiment of the adapter <NUM> it is however clear that other solutions and designs are possible. The holes and the arch shaped elements <NUM> may be arranged differently or the adapter <NUM> may comprise only one or several arch shaped elements <NUM>. In addition, the adapter may comprise two longitudinal webs <NUM> instead of one. The arch shaped elements <NUM> are however beneficial since they provide a capability to absorb shocks or the like.

<FIG> illustrates a bigger perspective view of the battery unit <NUM> with the lower part of the handle unit <NUM> illustrated.

The circuit board <NUM> mounted on the frame <NUM> is visible and also the adapter-frame fastening mechanism <NUM> that connects the frame <NUM> to the adapter <NUM>. The cables <NUM> from the battery unit <NUM> are connected directly to the circuit board <NUM>. The adapter <NUM> is fastened to the battery unit <NUM> via the adapter-battery unit fastening mechanism <NUM>. The battery unit housing <NUM> comprises battery unit electronics <NUM>, such as circuits and processors that are connected to the battery power ports and therewith the battery and the cables <NUM> that lead to the circuit board <NUM> of the handle unit <NUM>. From <FIG> it becomes well visible how the interface handle unit <NUM> - battery unit <NUM> is designed and how the adapter <NUM> provides shock protection. The adapter <NUM> and the frame <NUM> in the figures are made of aluminum to provide good stability and a light weight. Other materials are possible as described herein. It is also possible to choose different materials for the frame <NUM> and the adapter <NUM>. The screws and bolts used for the fastening mechanism can likewise be made of aluminum or steel.

<FIG> illustrates an explosion drawing of the frame <NUM> and the different components of the control button <NUM>. The control button <NUM> comprises the trigger <NUM>, the trigger adapter <NUM> that embeds and holds the trigger <NUM> via the splint <NUM> (c. <FIG>) and a spring <NUM> that is embedded in the receiving cavity <NUM> for the control button in the frame <NUM>. <FIG> further illustrates the reverse button recess <NUM> and the frame- motor unit fastening mechanism <NUM>. The frame-motor unit fastening mechanism <NUM> comprises a part at an upper end of the frame <NUM> that is built stronger and sturdier than the rest of the frame <NUM>. Typically this part at the upper part of the frame <NUM> is about <NUM>% to <NUM>% thicker than the rest of the frame <NUM>. In a similar manner, a lower end of the frame <NUM>, which lower end comprises of the adapter-frame fastening mechanism <NUM> is designed thicker and therewith sturdier than the rest of the frame <NUM> also with an increased thickness of about <NUM>% to <NUM>% thicker than the rest of the frame <NUM>. The threaded holes for receiving bolts and/or screws are embedded in these parts of the upper end and the lower end of the frame <NUM>. <FIG> further illustrates the bolt opening <NUM> for receiving the bolt <NUM> and its sleeve <NUM>. The bolt opening <NUM> is also designed and foreseen in the circuit board <NUM> and the insulation and protection element <NUM> so that this components can be attached to the frame <NUM> via the bolt <NUM> and the sleeve <NUM>.

<FIG> illustrates an explosion illustration of the handle unit <NUM> and the battery unit <NUM> of the pistol tool without the pair of outer handle covers <NUM>. <FIG> however illustrates the inner handle covers <NUM>, insulation and protection element <NUM>, the frame <NUM>, the circuit board <NUM>, the battery housing <NUM>, the trigger <NUM> of the control button <NUM> and a pair of antennas <NUM> used for communication with a factory network for example. The circuit board <NUM> may extend on both sides of the frame <NUM> as illustrated in <FIG> and it may also have a part that is embedded in the battery housing <NUM> when assembled. This part of the circuit board <NUM> that is embedded in the battery housing <NUM> when the pistol tool is assembled can for instance be positioned just below the adapter <NUM>. <FIG> further illustrates how the circuit board <NUM> and the insulation and protection element <NUM> extend around the receiving cavity <NUM> for the control button. The trigger <NUM> and the trigger adapter <NUM> including the spring <NUM> and the splint <NUM> that holds the trigger <NUM> in the trigger adapter <NUM> are also well visible in <FIG>. Pushing the trigger <NUM> will send a signal to the circuit board <NUM>, for instance via a hall sensor, so that the circuit board <NUM> controls the motor unit <NUM> and the motor, respectively.

The antennas <NUM> are configured to be attached to the battery housing <NUM> on either side of the adapter <NUM>. The pair of antennas <NUM> can thereby be directly connected to circuit board <NUM> of the pistol tool <NUM> or via the cables <NUM>. <FIG> further illustrates the bolt <NUM> and the sleeve <NUM> for mounting the insulation and protection element <NUM>, circuit board <NUM> and the inner handle covers <NUM> to the frame <NUM>.

The frame has been illustrated as a plate-like element it is however clear the it can have another design and structure such as a truss or framework design or it may contain multiple holes for optimizing weight.

Claim 1:
A power tool comprising a motor unit (<NUM>) comprising a motor (<NUM>) and a drive axle (<NUM>) connected to the motor (<NUM>), a battery unit (<NUM>) configured to receive a battery and a handle unit (<NUM>) interconnecting the motor unit (<NUM>) and the battery unit (<NUM>), the handle unit (<NUM>) comprising:
- a frame (<NUM>) extending from the motor unit (<NUM>) to the battery unit (<NUM>);
- a control button (<NUM>) mounted to the frame (<NUM>) for controlling the power tool;
- a circuit board (<NUM>) mounted to the frame (<NUM>) and connected to the control button (<NUM>);
- cables (<NUM>, <NUM>) interconnecting the battery unit (<NUM>), the circuit board (<NUM>) and the motor unit (<NUM>);
- an antenna (<NUM>) connected to the circuit board (<NUM>) for communication of the power tool with external devices;
- a pair of outer handle covers (<NUM>) for covering the handle unit (<NUM>);
characterized in that the frame (<NUM>) is made of an electrically conductive material, and wherein the handle unit (<NUM>) further comprises an adapter (<NUM>) that is connected to the frame (<NUM>) and the battery unit (<NUM>), whereby the adapter (<NUM>) is electrically conductive and designed to have shock absorbing capabilities.