Abstract:
In an engine driven hand-operated tool such as a chain saw, hedge trimmer, drill hammer and the like, cooling fluid for the engine downstream of the engine, so as to have been heated by the engine, is moved through a hollow handle of the tool to heat the handle.

Description:
FIELD OF THE INVENTION 
     This invention relates to an engine driven hand-operated tool, especially a motor or a chain saw, with at least one handle which is configured hollow, and with a driving engine, especially an internal combustion engine or an electric motor and a fluid cooling with a cooling fluid flow being provided for driving engine. 
     BACKGROUND OF THE INVENTION 
     When working longer with an engine driven hand-operated tool which transfers high vibrations to a handle, it can come in dependence on these vibrations to circulatory disturbances in the hands of the operator who holds the hand-operated tool with the handle. This illness is also known as ischemic fingers illness. Such circumstances appear especially when using motor or chain saws, whereby low temperatures still reinforce this effect. Therefore, chain saws with an electric handle heating have already been constructed and marketed. However, because of the very low number of items produced, these chain saws are relatively expensive, have high production costs and high development costs, and all machines of a construction kit of the same type, even those without handle heating, must be provided with the necessary construction sparings for the components of the electrical heating, such as generator, cabling and switches, which means for the user without handle separation unnecessary construction width and weight, as well as disadvantages when handling. 
     The aim of this invention is to make available an improved hand-operated tool of the above mentioned type which eliminates the above mentioned disadvantages and thus prevents, at low temperatures, the risk of permanent impairments due to circulatory disturbances in the hands of an operator. 
     SUMMARY OF THE INVENTION 
     To this purpose, it is provided for according to the invention that the handle shows at least one inlet opening and at least one outlet opening, whereby the inlet opening and the outlet opening are placed in such a way that the cooling fluid flow downstream of the driving engine flows into the handle over the inlet opening, flows through the handle over a predetermined section and flows out of the handle again by the outlet opening. 
     This has the advantage that a handle heating is realized at low cost and without additional construction space required, whereby additional devices such as, for example, a generator, a cabling or a switch are not necessary. Each engine driven hand-operated tool can also be equipped later with this handle heating according to the invention simply and at low cost. 
     In a preferred embodiment, the fluid cooling is an air cooling and the cooling fluid flow a cooling air flow. 
     A simple and low cost assembly is obtained by the fact that an air conducting device fixed on the handle adjacent to the inlet opening is placed and configured in the cooling air flow downstream of the driving engine in such a way that the cooling air flow is at least partially intercepted by the air conducting device and is guided into the inlet opening on the handle. This air conducting device is configured, for example, as an air conducting sheet and is fixed or pushed-on or snapped-on onto the handle. 
     In an alternative preferred embodiment, the fluid cooling is a water cooling and the cooling fluid flow a cooling water flow. 
     A simple power regulation of the handle heating or of a temperature on the handle is obtained by the fact that a first slide is provided for the alternative opening, partial opening or closing selectively the inlet opening and/or a second slide for the opening, partialy partiality opening or closing the oulet opening. 
     In an appropriate manner, the handle is a stirrup-shaped handle or an allround handle and is configured, for example, as a metal tube or is made of plastic. 
     In a preferred embodiment, a device for guiding the cooling air flow downstream of the driving engine to the inlet opening is configured integrated into a tank/handle system. 
     The invention will be explained in more detail below with reference to the attached drawings. 
    
    
     BRIEF DESCRIPTION OF THE INVENTION 
     FIG. 1 is a schematic perspective representation of a first preferred embodiment for which air conducting and admission are integrated into the tank. 
     FIG. 2 is a schematic perspective representation of a second preferred embodiment for which air conducting and admission are integrated into the allround handle. 
     FIG. 3 is a schematic perspective representation of the version of FIG. 2 seen from the opposite side. 
     FIG. 4 is a schematic perspective representation of the version of FIG. 1 seen from the opposite side with integrated adjusting element. 
     FIG. 5 is a further schematic perspective representation of the version of FIG.  4 . 
     FIG. 6 shows in schematic perspective representations the heating of the rear handle. 
     FIG. 7 is a schematic perspective representation of the version of FIG. 6 with an integrated actuator, represented from the opposite side. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The invention will be explained below by means of the hand-operated tool in form of a chain saw with internal combustion engine represented in FIGS. 1 to  7 , whereby this is to be understood only as an example. The invention can be used for every engine driven hand-operated tool with handle such as, for example, hedge shears, drill hammer etc. 
     The chain saw  100 ,  200 ,  300 ,  400  represented in different embodiments according to FIGS. 1 to  7  comprises a stirrup-shaped handle  10 , a rear handle  11 , an internal combustion engine  12  and a hand-guard  14  (FIGS. 1 to  4 ). 
     For the embodiments  100 ,  200 ,  300  represented in FIGS. 1 to  5 , an air conducting device  16 / 17  is provided for which conducts a cooling air flow  18  downstream of the internal combustion engine  12 , i.e. an air flow  18  which has already absorbed and dissipated heat from the internal combustion engine  12 , to an inlet opening  20 . This cooling air flow  18  heated by the waste heat of the internal combustion engine  12  now heats, for its part, the stirrup-shaped handle  10  by flowing through the hollow stirrup-shaped handle which constitutes an air channel  13  so that a hand of an operator who helds the hand-operated tool with the stirrup-shaped handle is heated correspondingly. 
     This cooling air flow  18  escapes at an outlet opening  22  again out of the stirrup-shaped handle  10  so that continuously newly heated air  18  can flow over the air conducting device  16 . For the embodiment  100 ,  300  represented in FIGS. 1,  4  and  5 , the air conducting device  16  or the air inlet is integrated into the stirrup-shaped handle  10  into a fuel/handle system  32 , whereas in the embodiment  200  according to FIGS. 2 and 3 the air conducting device  16  is configured as a separate air conducting sheet which is pushed onto the stirrup-shaped handle  10  or injected on the stirrup-shaped handle. 
     For the third preferred embodiment  300  represented in FIGS. 4 and 5, an adjusting element  24  is additionally provided which optionally closes, partially opens or totally opens the inlet opening  20 , which can be seen in FIG. 5, on the stirrup-shaped handle  10  by moving in direction of the arrow  25 . With this adjusting element  24 , the temperature or the thermal output on the stirrup-shaped handle  10  can be adjusted by selecting its position correspondingly. For the position shown in FIG. 4, the adjusting element  24  is in the position “completely open”, a maximal heating capacity being available on the stirrup-shaped handle  10 . As it furthermore results from FIG. 4, an additional screwed connection  26  is provided on the stirrup-shaped handle  10  which makes available an additional support and bearing of the stirrup-shaped handle  10 . Corresponding ribs (FIG. 5) serve as chip protection in front of the inlet opening  20 . 
     Due to the at least partial air deviation of the warm cooling air  18  coming from the engine  12  through the stirrup-shaped handle  10 , the stirrup-shaped handle is heated so that the probability of the ischemic fingers illness is considerably reduced without additional components such as generator, electrical heat conductor, cabling etc. Here, the air conducting device  16  is provided on the coupling side on the stirrup-shaped handle as an air trap which deviates at least a part of the warmed cooling air  18  into the stirrup-shaped handle  10 . The air  18  escapes for example on the magnet side below from the outlet opening  22  (FIG.  1 ). The handle heating according to the invention can be realized with a stirrup-shaped handle  10  as a metal tube as well as with a stirrup-shaped handle  10  made of plastic. 
     For a metal tube handle  10 , the inlet opening  20  and the outlet opening  22  are built-in for example by radial mechanical subsequent retouching work. Alternatively, the openings  20 ,  22  are realized by add-on elements such as, for example, a cast metal part. Furthermore, it is possible to integrate also the inlet and outlet openings  20 ,  22  into the tank  32 , the cooling air flow  18  being then introduced preferably axially into the metal tube handle  10 . 
     For a plastic allround handle  10 , the openings  20 ,  22  can be produced by subsequent work, by a subsequent displacement of inserts in the plastic tool or by a stirrup-shaped handle produced in grain melting technology. 
     For the embodiment represented in FIGS. 6 and 7, there takes place a heating of the rear handle  11  of the chain saw  400 . The air flow  18  heated by waste heat flows into the inlet opening  20 , is guided through the air channel  13  through the rear handle  11  into the outlet opening  22 . The air channel  13  is integrated into the fuel tank/handle system  32 . In FIG. 7, the rotatable adjusting element  24  for adjusting the heating capacity is represented; it snaps in into the different selection positions for the heating capacities which are characterized with the symbol positions  30 . The opening and closing of the air channel  13  is carried out by rotating the adjusting element  24 .