Abstract:
The invention relates to a gasoline motor powered, hand-operated working machine, which is stopped by short-circuiting an electric circuit ( 70 ), said stop device being designed in the form of an electric switch comprising a stop control ( 11 ), which can be moved manually between two end positions; a drive position for start of the motor and for motion of the motor, in which drive position said circuit is not short-circuited, and a fixed stop position in which the circuit is short-circuited and the stop control is locked. The characteristic features are that the electric circuit is short-circuited also in a non-locked intermediate position (II) of the stop control, which the stop control must pass, if it is brought all the way from the drive position (I) to the fixed stop position (III), and that a spring ( 60 ) is provided to return the stop control to the drive position, if the stop control is moved from the drive position to said intermediate position and then released, implying that the intermediate position is a re-springing stop position of the stop control.

Description:
TECHNICAL FIELD 
     The invention concerns a stop device for a gasoline motor powered, hand-operated working machine, which is stopped by short-circuiting an electric circuit, said stop device being designed in the form of en electric switch comprising a stop control, which can be moved manually between two end positions; a drive position for start of the motor and for motion of the motor, in which drive position said circuit is not short-circuited, and a fixed stop position in which the circuit is short-circuited and the stop control is locked. 
     The invention also concerns the gasoline motor powered, hand-operated working machine which is provided with the stop device. 
     BACKGROUND OF THE INVENTION 
     According to current safety regulations, the stop control of gasoline motor powered, hand-operated working machines must have a fixed stop position, which shall be possible to be adopted therein that the operator moves the stop control from the drive position to the fixed stop position through a single, uninterrupted movement. The reason for this regulation is that the machine safely shall be able to be stopped in an emergency situation. But also in case of occasional stops, e.g. for periods of rest, refuelling etc., the stop control of existing machines need to be moved to the fixed end stop in order to stop the motor. Before the machine can be restarted, the stop control must be brought back to the drive position. It frequently happens that the operator forgets to do that and repeatedly pulls the starter rope until he becomes aware of his mistake, and this is particularly true when existing stop controls have the shape of a knob or slide which does not provide any readily visible signals. Meanwhile the engine often has become “wet”, which makes the start difficult. 
     BRIEF DISCLOSURE OF THE INVENTION 
     It is the purpose of the invention to address the above mentioned problem. According to a first aspect of the invention, which concerns the stop device which is first mentioned in the preamble, the invention is characterised in that the electric circuit is short-circuited also in a non-locked intermediate position of the stop control, which the stop control must pass, if it is brought all the way from the drive position to the fixed stop position, and that a spring is provided to return the stop control to the drive position, if the stop control is moved from the drive position to said intermediate position and then released, implying that the intermediate position is a re-springing stop position of the stop control. According to this aspect of the invention, the operator thus can choose either to move the stop control from the drive position beyond the intermediate position and further on to the fixed stop position, a possibility which can be used in emergency situations, or e.g. when the job has been finished for the day, or to move the stop control only to the intermediate position so that the machine is stopped by short-circuiting the electric circuit, whereafter the stop control is released and is automatically caused to spring back to the drive position. In the latter case, the operator need not think of positioning the stop control in a proper position before start. 
     According to another aspect of the invention, the stop device is characterised in that it is designed as a toggle switch including a rocker which is turnable about an axis of rotation, that the rocker has a first, outer lever with a grip member and a second, inner lever, that the rocker is biased by the force of the spring which acts against said inner lever, and that the movable contact member is provided to be conveyed by the inner lever as the rocker is being turned against said re-springing and/or fixed position of contact. 
     According to still another aspect of the invention, the stop device is characterised therein that it is designed as a toggle switch, said stop control forming a rocker, which includes a first lever which is turnable about an axis of rotation between said drive position and said fixed stop position, that said first lever is substantially turned into a wall of the working machine in the drive position of the machine, when the stop device is mounted on a working machine, and that it in the fixed drive position substantially is turned out from said wall. According to this aspect of the invention, the turned out lever including the grip member in the fixed stop position acts as a readily observable signal to the operator that the stop device has adopted its fixed stop position and that the machine therefore cannot be started. This signal is enhanced if the stop control including the grip member has a bright signal-colour. The turned out position of the stop control in other words gives the operator an impulse to turn in the control with said outer lever as an initial measurement before start. 
     According to yet another aspect of the invention, which relates to the gasoline motor powered, hand-operated working machine, the working machine is of the well known type which includes a rear operating handle with a starter throttle control on one side of the operating handle, which starter throttle control must be pressed into the operating handle before start. The characteristic features of the invention according to this aspect of the invention are that the stop device is designed as a toggle switch on a wall of the machine at the side of the starter throttle control and that a first, outer lever of a rocker of the toggle switch, in the fixed stop position, is substantially turned out from the wall of the machine at the side of the operating handle in a direction towards the starter throttle control to a position outside of the starter throttle control, such that the starter throttle control is made difficult to access by the machine operator, while said lever in the drive position is turned away from the starter throttle control and substantially into said wall, such that the starter throttle control is made easy to access and the rocker is protected, so that the engine is not unintentionally switched off during operation. 
     Said aspects of the invention can be combined with one another but in some respects be employed independent of each other. 
     Further aspects and characteristic features of the invention will be apparent from the appending patent claims and from the following detailed description of the invention. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     In the following detailed description of the invention, reference will be made to the accompanying drawings, in which 
     FIG. 1 shows a conceivable application of the invention in a perspective view of a schematically shown portion of a machine comprising a stop control in its drive position; 
     FIG. 2 shows the same machine with the stop control in a fixed stop position; 
     FIG. 3 shows a stop device in a perspective view with the stop control in the drive position; 
     FIG. 4 shows the stop device with the stop control in a re-springing stop position; 
     FIG. 5 shows the stop device with the stop control in a fixed stop position; and 
     FIG. 6 schematically illustrates the cooperation between a fixed and a movable contact member included in the stop device. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference first to FIG.  1  and FIG. 2, there is schematically shown the rear wall  1  of a motor housing  2  of a gasoline motor powered, portable and hand-operated working machine, more particularly a cutter. An operating handle, intended to be gripped by the operator&#39;s right hand, is designated  3 . In connection with the operating handle there is in a conventional way a throttle control  4  under the operating handle, an idling catch  5  on the upper side of the operating handle, and a starter throttle control  6  on the left hand side of the operating handle  3 . To make it possible to start the motor, the starter throttle control  6  in a manner known per se first must be pressed into the operating handle  3  by the operator. This is normally made by the operator&#39;s right hand thumb. 
     On the rear side  1  of the motor housing, to the left of the operating handle  3  and at level with the starter throttle control  6  there is provided a stop device  10  for the engine. The stop device  10  comprises a stop control  11 , which is designed with a rocker  12  with a finger grip  13 . The stop control  11  is operated by turning the rocker  12  by means of the finger grip  13  about a vertical axis of rotation  15 , FIG.  3 . 
     When the rocker  12  with the finger grip  13  is in the drive position of the stop control  11 , the rocker  12  is substantially turned in into and is protected in the rear wall  1  of the motor housing  2 , so that only the finger grip  13  projects to any essential degree from the motor housing wall. The starter throttle control  6  in this position is easy to access by the operator and allows start of the engine, FIG.  1 . When the stopper control  11  with the rocker  12  and the finger grip  13  is in the fixed stop position, FIG. 2, the rocker with an outer lever  50 , which has the finger grip  13  in the outer end thereof, on the other hand is turned out from the motor housing wall  1 , so that the finger grip  13  prevents the operator to access the starter throttle control  6  with his thumb. At least this requires so much trouble that the operator becomes aware of the fact that the stop device is in its fixed stop position. The operator therefore is more or less forced to move the stop control  11  from its fixed stop position, FIG. 2, to the drive position, FIG. 1, before he can press in the starter throttle control  6  and start the engine. At that type of machines where the motor stop device is located, or can be located, at the rear side of the motor housing adjacent to the starter throttle control  6 , the described arrangement, according to one aspect of the invention, thus is a very efficient means for preventing the operator to start the engine with the stop device in the stop position, but also if the stop device  10  has another location than adjacent to the starter throttle control  6 , the projecting position of the rocker  12 , and particularly the position of the projecting finger grip  13 , is a readily visible indication that the stop device is in its fixed stop position, which can prevent many attempts to start the engine in that position. Moreover, the signal action of the finger grip  13  in the turned out position can be enhanced, if it has a different colour than the wall  1 . 
     According to the embodiment the stop device  10  thus is designed to prevent attempts to start in the fixed stop position independent on mounting location; on one hand therein that the rocker with its finger grip  13  projects pronouncedly in the stop position, and on the other hand due the “interior” design of the device  10  which shall be described in the following. 
     FIGS. 3-6 show more in detail how the stop device  10  is designed according to a preferred embodiment. The stop device  10  can be mounted on the machine on and in the rear wall  1  of the motor housing  2 , as has been described above, wherein, in combination with the starter throttle control  6 , there is achieved the specific effect which also has been described above, but the stop device  10  can also be mounted at any other location on the machine, e.g. on the side of the machine in a manner which is conventional, as has been mentioned in the foregoing, as will be described below. 
     Whether the stop device  10  is mounted on the rear side  1  of the motor housing or at any other location of the machine, the stop device  10  preferably is mounted such that the axis of rotation  15  is vertical in the normal working state of the machine. The denominations of the various parts of the stop device are based on that orientation, although also other orientations of the stop device  10  in principle can be conceived. 
     The stop device  10  consists of a toggle switch having a breaker housing  17  of electrically insulating plastic material. A circumferential frame, which constitutes an integrated part of the breaker housing  17 , is denoted  18 . The frame  18  abuts the exterior of the machine, as is shown in FIG.  1  and FIG. 2, while the rest of the breaker housing  17  is recessed in the machine wall. At the interior of the frame  18 , the breaker housing  17  has an upper wall  19 , a lower wall  20  with a screw hole  21  for assembling the stop device  10  with the machine, a left hand wall  22 , a right hand wall  23 , and an inner wall portion  24 , which only partly covers the interior of the breaker housing  17 . 
     In the breaker housing  17  there is provided a fixed contact member  27 , which has the shape of a bent piece of metal sheet. One end  28  of the metal sheet (the fixed contact member)  27  extends through an opening  30  in a projection  31  of the breaker housing  17  at level with said inner wall portion  24 . Inside of the opening  30  the sheet extends along the front wall  22  of the breaker housing, through an opening  32 , FIG. 4, in the left hand wall  22 , and then forms a sharp bend  33  (dotted in FIG.  5 ), and further a circular arc  34 . Within the region of the circular arc  34 , one edge of the metal sheet  27  abuts the lower wall  20  of the breaker housing  17 . The other, free edge of the metal sheet  27  forms a cam curve  26 . The other end  29  of the metal sheet/the fixed contact member  27  is secured in the lower wall  20  of the breaker housing. 
     FIG. 6 shows the circular arc shaped portion of the fixed contact member (metal sheet)  27  in a conceived flattened shape. On the cam curve  36  there is an initial portion  40 , then an upwardly inclined portion  41 , a crest  42 , and after the crest  42  a recess  43  having a second, downwardly sloping portion  44  between said crest and the bottom of the recess. The opposite side  45  of the recess  43  rises steeply. 
     The stop control is part of a rocker  12 , designed as a double armed lever, which is turnable about the vertical axis of rotation  15 . More particularly, the stop control forms the main part of a first or outer lever arm, which is denoted  50 . The finger grip  13  constitutes the outermost part of the outer lever arm  50 . The second or inner lever arm is denoted  51 . In the drive position of the stop control the outer lever arm  50  is recessed in the breaker house  17 , as is shown in FIG. 1, except the finger grip  13  and a portion  52  at the side thereof, on which the sign STOP is provided. In the fixed stop position, on the other hand, the lever arm  50  with the finger grip  13  is turned out from the breaker housing and out from the motor housing wall  1 , FIG.  2 . 
     The inner lever arm  51  of the rocker  12  is designed as a sector of a circle. In its right hand end said sector of a circle has a protrusion  53 , FIG. 3, directed towards the lower wall  20  of the breaker housing. 
     According to the embodiment, the stop device (toggle switch)  10  comprises a movable contact member, which can be moved by means of the stop control  13 , wherein the fixed contact member (metal sheet)  27  has a first and a second contact seat provided for the movable contact member. The first contact seat, which the movable contact member adopts in the fixed stop position of the stop control, is said recess  43  in the metal sheet, while the second contact seat, which corresponds to the intermediate position of the stop control, does not have any holding means for retaining the movable contact member but consists of the upwardly inclined portion  41  of the metal sheet. 
     A metal spring, more particularly a helical torsion spring, is denoted  60 . Said metal spring  60  has several functions. Firstly, one projecting end  61  of the spring forms said movable contact member therein that it is pressed by the spring against the protrusion  53  on the inner lever arm  51  and is moved by said protrusion as the rocker  12  is turned to stop positions. Secondly, the whole of the metal spring  60  as well as the stationary contact member (metal sheet)  27  form part of the short-circuiting circuit that shall short-circuit the electric circuit  70 , FIG. 3, as mentioned in the preamble. The stationary end  62  of the metal spring  60 , which extends through the lower wall  20  and/or the inner wall  24  therefore is connected to the metal motor housing or motor block of the working machine, which represents earth and constitutes one pole of the electric circuit  70 . Thirdly, the spring  60  serves to return the stop control  11  to drive position from said intermediate position by biasing the protrusion  53  on the inner lever arm  51  of rocker  12 . Fourthly, the movable end  61  of the spring has a locking function together with the metal sheet  27 . 
     The first end  28  of the stationary contact member (metal sheet)  27  is connected to the second pole of the electric circuit  70 . More particularly, the stop device  10  is provided to short-circuit the low voltage side (primary side)  71  of the ignition module of the engine. 
     The described device functions in the following way. It is assumed that the initial condition is that which is shown in FIG.  1  and FIG. 3, i.e. with the stop control in the drive position. The switch then is shut off, i.e. the short-circuiting circuit is not closed. The movable part  61  of the metal spring  60  then is in position I in FIG.  6 . In order to stop the engine according to the normal alternative, the operator turns the rocker  12  about its axis of rotation  15  by means of the finger grip  13 , wherein the rocker by means of the protrusion  53  on the inner lever arm  51  brings the movable end  61  of the metal spring into contact with metal sheet  27  in the region of the sloping portion  41  of the cam curve  36 , position II in FIG.  6 . Herein the short-circuiting circuit is closed and the engine stops. After a short holding time in that position, as is shown in FIG. 4, representing said intermediate position, the operator can release the finger grip  13  causing the rocker  12  and hence the stop control  11  to return to the drive position, FIG. 3, by means of the spring  60 . If the holding time in the intermediate position, position II, is too short and if there is a substantial mass rotating in the machine, there is a risk that the engine may self-start when the stop control is returned to drive position. If that would occur in a normal situation, the operator repeats the stop procedure to bring the engine to stop. In an emergency situation, or if the operator from any other reason wishes to bring the stop control to the fixed stop position, the operator moves the stop control  12  in a single, uninterrupted movement from drive position, FIG. 3, to the fixed stop position, FIG.  5 . During this longer turning movement the movable end  61  of the metal spring  60  is urged to pass the crest  42  of the cam curve  36  in order thereafter to snap-in in the recess/contact seat  43 , position III in FIG. 6, in which the end  61  of the spring is locked, so that the movable contact member cannot leave its seat in the recess  43  by the force of the spring only. This position thus represents a fixed stop position, from where the movable contact member only can be removed by the operator&#39;s force, directly applied on the stop control  11  in a clockwise direction with reference to FIG.  5 .