Abstract:
The motor-driven hedge clipper has a machine housing; a main handle provided with one switch button; a hollow U-shaped auxiliary handle and a single deadman switch operating mechanism for turning off the hedge clipper when not activated by an operator. The single deadman switch operating mechanism includes one and only one U-shaped button element movably mounted in the auxiliary handle and extending around the inner contour of the U-shaped auxiliary handle, so as to be movable radially outward and inward relative to the auxiliary handle in all directions; a mechanical biasing device for urging the button element radially outward, whereby the button element moves radially outward when not being pressed radially inward into the auxiliary handle; and a cable line arranged in the auxiliary handle and connected to the button element, so that it moves exclusively longitudinally when the button element is moved radially inward in any direction so that the deadman switch operating mechanism is activated and the hedge clipper is turned on.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to hedge clippers. 
     Hedge clippers are usually provided with auxiliary handles which, for the safety of the operators are set into operation and can be held when both an on-switch on the main handle and also an additional switch activating button in the auxiliary handle remain pressed. When a switch actuation is released, the machine stops immediately. Therefore, it is not possible to operate the hedge clipper with only one hand which can lead to certain risks. 
     The European patent document EP-A-0 214 455 discloses a hedge clipper in which a C-shaped auxiliary handle is provided and has both legs as well as a web each supporting a control button. Thereby the buttons in all gripping positions of the hand which holds the auxiliary handle can be pressed simply and with good access. Each control button operates independently from the other buttons and acts on a single cable line which is prestressed and arranged in the interior of the hollow auxiliary handle. It can be deviated transversely to its longitudinal axis and because of the transverse deviation its ends tend to displace longitudinally. Since one of the ends of the cable line is fixedly connected in the interior of the auxiliary handle while the other end is arranged displaceably on an actuating element of the deadman switch, therefore during the transfer deviation of the cable line, regardless from which control button, the moveable cable line ends together with the actuating element are displaced and the deadman switch closes the operational current circuit for operation of the hedge clipper. 
     The known hedge clippers are composed of a plurality of different components, since the cable line is guided in the interior of the C-shaped auxiliary handle over its total length of the C-shape and over three control buttons supported on each C-leg independently from one another. As a result, the known hedge clippers have a relatively complicated construction and are relatively expensive. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a hedge clipper which avoids the disadvantages of the prior art. 
     In keeping with these objects and with others which will become apparent hereinafter, one feature of present invention resides, briefly stated, in a hedge clipper in which the auxiliary handle has only one button element which is arranged relative to the auxiliary handle so that it is moveable radially outwardly in all directions, and the cable line is driven with it relative to the switch, wherein the cable line is coupled with the button element so as to be exclusively longitudinally deviatable. 
     When the hedge clipper is designed in accordance with the present invention, it has a small number of parts and a simple construction of the auxiliary handle and therefore can be produced simply in a cost-favorable manner, and also the switch actuation of the deadman switch is especially robust. 
     Moreover, the actuating force on the auxiliary handle for switch actuation is especially low in any gripping position, and the control button can be handled in each actuation direction so that it is easy accessible and convenient. 
     Since only one button element is supported on the auxiliary handle in each leg moveably, the auxiliary handle can be produced with great tolerances and low number of components. 
     The cable line is very short, and shorter than the length of the legs. Therefore, it can be arranged in the handle especially easy and mounted very simply. 
     The cable line, despite the transfer displacement, remains longitudinally actuatable. Therefore, it is subjected to smaller loads and lower material fatigue. 
     The cable line is arranged between the supporting points of the button element and guided over a stationary projection of the auxiliary handle between the supporting points. Thereby a transverse displacement of the cable line during the longitudinal actuation is possible in two directions. 
     The cable line is provided with loops at both ends. Thereby it is especially easy to mount it between the switch actuator and the button element. 
     A part of the button element which is opposite to the part carrying the end of the cable line forms a guiding incline, in particular a guiding curve for the cable line. Therefore the cable line is guided reliably by abutting against a large surface and also is supported in wear-free manner. 
     The cable line can be formed in a sine shape. In this construction it is especially easy to be tensioned, so that during the actuation of the button element a very direct response of the switch is obtained. 
     The cable line is rotatably supported on a suspension pin between the guiding incline of the button element and the mounting, and also is guided on a cam disc which supports the plunger. Therefore during loading of the cable line along its axis, its wear is especially low. 
     The button element is held in the tensioned position by a spring in the interior of the auxiliary handle. Therefore its operability and position-safety is guaranteed. 
     The button element is provided substantially at an end of its leg with a transverse web connected to it. Therefore it is especially form-stable and deformation-secure, so that during actuation it guarantees a very direct response of the switch. 
     The button element is provided with recesses at least on each end of the leg, with stationary cams of the auxiliary handle engaging in the recesses. Therefore the actuation path of the button element over a predetermined actuation stroke in all operational direction is determined or limited, and the button element is secured from falling out from the auxiliary handle. 
     The button element can be formed as a hollow body provided with many interior ribs. With this construction, it is especially light, bending-resistant and operation-friendly. 
     The button element can be provided with a centered support in the region of its centering dome located centrally on the upper leg, relative to the auxiliary handle over an elastic loop. In this construction, a very simple restoring mechanism is provided for the button element, so that the button element after the actuation is always returned to its initial position. 
     The elastic loop which operates as a string is pre-tensioned through a projecting finger of the button element, and a counter finger spaced from it and located opposite to it on the auxiliary handle is held. Therefore, this construction is especially mounting-friendly. 
     The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a view showing a hedge clipper with an auxiliary handle in accordance with the present invention; 
     FIG. 2 is a view showing a longitudinal cross-section of the auxiliary handle; 
     FIG. 3 is a view showing an enlarged fragment of FIG. 2; 
     FIG. 4 is a view showing a movement transmitting element between a cable line and a deadman switch when a button element is not actuated; 
     FIG. 5 is a view showing a movement transmitting element of FIG. 4 when the button element is actuated; and 
     FIG. 6 is a view showing an end side of a cylinder-slot body of a plunger. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     A hedge clipper  10  which is shown in FIG. 1 has a central machine housing  12 . The housing accommodates a not shown electric motor as well as a drive for a hedge clipper cutting unit  20  or a hedge clipper cutter. 
     When considered at the right in the observation direction, a handle  14  is arranged at the rear end of the machine housing  12  and identified as a spade handle. It has a switching button  16  for actuation of an on-off switch. The machine housing  12  is provided laterally with a ventilation slot  17 , and an electric cable  18  extends from it through the rear end of the handle  14 . The hedge clipper cutting unit  20  is located at the front side on the machine housing  12  and provided with not shown reciprocating hedge clipper cutters and cutter holders. 
     The machine housing  20  carries a forwardly inclined auxiliary handle  22 . The auxiliary handle  22  is hollow and composed of two half-shells  34 ,  36  which are connected with one another by screws  30 . A button element  26  is located within an inner contour of the auxiliary handle  22 . It is formed so as to substantially follow the U-shaped contour of the auxiliary handle  22 . It is connected by a transverse web  28  in the region of its leg ends. Due to the arrangement of the transverse web  28  the button element  26  is substantially reinforced, and the not shown switch can be actuated in the interior of the machine housing  12  without a gap. 
     In order to work with the hedge clipper  10  in accordance with the present invention, an operator grasps the rear handle  14  with its main hand and the auxiliary handle  22  with its guiding hand. When the main hand now actuates the button  16  and simultaneously the guiding hand actuates the button element  26 , the power supply circuit of the not shown motor is closed, the motor is set in operation, and the hedge clipper is driven in a reciprocating fashion. 
     The auxiliary handle  22  which is C-shaped and shown in FIGS. 2 and 3 in a partially broken manner, has an A-shaped button element  26 , and a lower and upper shell-shaped housing parts  34 ,  36 . Their inner periphery has a not shown slot which is dimensioned so that the button element  26  can displaceably pass through it into the interior of the auxiliary handle  22 . The auxiliary handle  22  has four screw domes  32 ,  32 ′, with a screw  30  fixed in each of them. Therefore the lower and the upper housing halves  34 ,  36  of the auxiliary handle  22  are assembled to form a unit. 
     The button element  26  is formed as a hollow body which is provided with a plurality of inner ribs. It is supported in the region of a mammilated centering dome  46  over an elastic loop  46 ′″ relative to the auxiliary handle  22  so as to be centered. For this purpose the elastic loop  46 ′″ which operates as a spring is held in a pre-stressed position by a projecting finger  46 ′ of the button element  26  as well as a spaced counter finger  46 ″ of the lower shell  34  of the auxiliary handle  22 , located opposite to the first mentioned finger  46 ′. The loop  46 ′″ returns the button element  26  back to its initial position after the actuation. 
     The button element  26  carries a non releasable wound loop cable line  42  on its lower leg region when considered at the left side in the observation direction. It is located on a projecting rib  38  whose end is formed as a finger  40 . The cable link  42  leads to the left and is curved over a screw dome  32 , on which it is supported so as to be downwardly pulled in a neutral switching position of the button element  26  and loaded with a spring  57 . 
     The other leg of the button element  26  carries a second rib  38 ′ which is mirror-symmetrical relative to the leg which carries the rib  38 . It is downwardly supported on a further screw dome  32 , similarly to the rib  38 . 
     The cable line  42  bridges a recesses  48  laterally outwardly in a lower region of the leg of the button element  26  and lies on a guiding incline  50  of the button element  26 . In its further course, the cable line  42  leads to the right in a curved position around a cam disc  52 , and from it further to a pin-shaped projection  54  which is connected with the cam disc  52  and non-releasably and fixedly engages with a loop-shaped end  43 . 
     The cam disc  52  is rotatably supported with an opening  53 ′ around a housing-fixed axle  53  and reduces the friction between the cable line  42  and the auxiliary handle during actuation of the cable line  42 . The reason is that the cable line  42  can roll over the curved surface of the cam disc, and the rolling friction without sliding friction is produced between the cable line  42  and the cam disc  52 . 
     The pin-shaped projection  54  is mounted on the cam disc  52  at a radial distance from its center on the turning lever  52 ′. The cam disc  52  engages with one end its turning lever  52 ′ in a forked-shape rear end of a plunger  56  which is guided in the grooves of ribs  61  of the auxiliary handle  22 . It acts during actuation of the button element  26 , together with the projection  54  and the turning lever  52 ′ to the right in the observation direction or in other words into the interior of the machine housing  12 . There it actuates a not shown switch D (shown in FIGS. 4 and 5) which operates as a deadman switch. 
     A reinforcing rib  52 ′″ extends between the projection  54  and the collar  52 ″ extending around the opening  53 ′. The reinforcing rib  52 ′″ holds the pin-shaped projection  54  over a part of its length in a non-deformable manner on the cam disc  52 . 
     The plunger  56  is supported in the longitudinal guide  58  in a friction-free and longitudinally displaceable manner in the lower region of the left leg  24  of the auxiliary handle  2 . It is engaged by spring  57  which urges the plunger  56  to the left as considered in the observation direction. For this purpose it is supported between a collar-shaped and fork-shaped cylinder head  56 ′ of the plunger  56  and two housing-fixed transverse ribs  61 . The movement in direction of the plunger  56  extends perpendicular to the longitudinal extension of the cable line  42 . 
     Because of the pre-tensioning force of the spring  57 , the plunger  56  together with the cam disc  52 , the cable line  42  and the button element  26  is returned to a neutral switching position after each actuation. In particular, the deadman switch D interrupts the operational circuit. 
     Mounting screws  60  extend through both leg ends  24  of the auxiliary handle  22 . They fix the auxiliary handle  22  on the machine housing  12  of the hedge clipper  10  in a flanged manner. Both the lower and the upper housing halves  34 ,  36  of the auxiliary handle  22  as well as the button element  26  carry a plurality of reinforcing ribs for improving their shape rigidity. 
     The button element  26  is supported turnably about a screw dome  32  operating as a rotary point, and at the same time longitudinally displacably. The button element  26  is supported freely displacably within certain limits relative to the screw dome  32 ′ operating as an abutment, in the central plane of the button element  26 . For providing the required movement freedom of the button element  26  relative to the auxiliary handle  22 , the elongated hole-shaped or key-hole-shaped recesses  62  are provided in the lower leg region of the button element  26 . They engage the screw dome  32 ,  32 ′ or at least abut on them in a neutral position of the button element  26 . 
     FIGS. 4 and 5 show the cam disc  52  and the plunger  56  individually on an explosion view, to illustrate the parts and operational elements of FIGS. 2 and 3. FIG. 4 shows the neutral position of the cam disc  52  and the plunger  56  with the not-actuated button element  26 , while FIG. 5 shows the deviated position of the cam disc with the actuated button element  26 . 
     The actuation of the deadman switch by the button element  26  of the auxiliary handle  22  is performed in the following manner: 
     When the button element  26  is displaced upwardly as considered in the observation direction, the spring  57  is compressed and the cable line  42  is pulled along its longitudinal axis so as to slide over the curvature of the dome  32 ′. The cable line  42  pulls the projection  54  in the counter clockwise direction around the axle  53  of the cam disc  54  together with it. The turning lever  52 ′ (FIGS. 4,  5 ) turns the plunger  56  to the right. 
     Since the turning lever  52 ′ is slidingly supported in the end-side slot  56 ″ of the forked-shape end of the cylinder head  56 ′ of the plunger  56 , the plunger  56  must follow the movement of the turning lever  52 ′. The material for the turning lever  52 ′ and the cylinder head  56 ′ is selected so that their movement transmitting regions during interengagement and sliding produce only minimal friction with resulting minimal wear. Therefore the cam disc  52  and the plunger  56  form an especially simple, robust and easily accessible force transmitting device. 
     When the button element  26  after engaging of the right leg  24  of the auxiliary handle  22  as considered in the observation direction is displaced to the right by the operator&#39;s hand, the cable line  42  is pulled slidingly to the right around or over the dome  32 . This leads to a longitudinal actuation of the cable line  42 . Therefore, similarly to the above described deviation, the projection  52  is moved by the button element  26  around the axle  53 , and the plunger  56  is moved again to the right. 
     When the left leg of the button element  26  as considered in the observation direction is displaced to the left, the cable line  42  is moved by the finger  40  in connection with the guiding incline  50  away from the screw dome  32 . Because of this movement, the cable line  42  rolls in the longitudinal direction around the curved rolling surface of the cam disc  52  and pulls it on the pin-shaped projection  54  around the axle  53  in a counterclockwise direction. Thereby the plunger  56  is driven again to the right linearly. 
     In all cases of the actuation, the recesses  62  operate in the region of the fibs  38  or the fingers  40 , for limiting of the actuation stroke of the button element  26 , which can move thereby over a very short fixed actuation path of the plunger  56  for releasing the deadman switch. Moreover, the elastic loop  46 ′″ which is formed for example as a rubber ring is returned back to its central initial position after releasing of the button element  26  and supports a fine controllability of the deadman switch. 
     It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above. 
     While the invention has been illustrated and described as embodied in hedge clippers, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. 
     Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.