Abstract:
A knife has a blade holder in a housing adapted to hold a blade and shiftable between a first cutting position with the blade projecting a little from the housing and a second position projecting somewhat more from the housing. An actuating element shiftable in the housing between a starting position and an actuating position is effective on a connecting linkage such that in a first orientation force is transmitted to the blade holder to retain the blade holder against moving into its retracted safety position from its first cutting position and in the second orientation the linkage does not prevent the blade holder from moving into its safety position from its second cutting position.

Description:
FIELD OF THE INVENTION 
     The invention relates to a knife comprising a housing in which a blade support can move between at least one safety position and at least one cutting position and where, in the safety position, a blade retained on the blade holder is in the housing so as to be inaccessible for the user and where, in the cutting position, the blade projects at least partially out of the housing, an actuator being movable from a starting position into an actuating position to shift the blade support from the safety position into a first cutting position, a connecting linkage being fixedly connected by a first pivot to the blade support and by a second pivot to an actuating element of the actuator. 
     BACKGROUND OF THE INVENTION 
     Such a knife is known from DE 197 23 279 [U.S. Pat. No. 6,148,520]. The knife has a housing in which a blade support can move between a safety position and a cutting position. In the safety position, the blade is retracted into the housing and cannot be touched by the user of the knife. In the cutting position, the blade projects out of an opening of the housing. The blade support can be moved by an actuator from the safety position into a first cutting position. A cutting force acting on the blade can shift the blade support from the first cutting position into a second cutting position. The second cutting position differs from the first cutting position in that the blade support can move back into the safety position even if the actuator is in the actuating position. In contrast, in the first cutting position with the actuator actuated, the blade support cannot move back into the housing. 
     In DE 10 2008 019 441 [US 2009/0260235], a knife is disclosed in which a lever is pivoted on the blade support and the actuator. By moving an actuator into an actuating position, the blade support can be moved from a safety position into a first cutting position. In the first cutting position, a support element fastened to the lever is supported on the housing. Moving the blade support from the first cutting position into the second cutting position, causes the support element to lose contact with the housing and the blade support can move back into the safety position even if the actuator is in the actuating position. 
     OBJECT OF THE INVENTION 
     It is the object of the invention to provide a knife which allows a simple construction and still ensures a safe handling. 
     SUMMARY OF THE INVENTION 
     The object is attained by a knife where the actuator has a connecting linkage with at least one connecting element. The connecting linkage is connected by a first pivot to the blade support and by a second pivot to an actuating element of the actuator. 
     The actuator is movable between a starting position and an actuating position. Moving the actuator from the starting position into the actuating position, causes the blade support to move from a safety position into a first cutting position. For example during movement of the blade support into the first cutting position, the at least one connecting element of the connecting linkage is in a first orientation. In the first orientation, the first pivot is spaced for example at a first spacing from the second pivot. The first orientation is, for example a stable orientation. Stable orientation in the meaning of the invention means that by means of the connecting linkage, forces transmitted from the actuating element to the blade support can force the blade support into a cutting position. 
     The blade support can be moved from the first cutting position into a second cutting position. In the second cutting position, the connecting linkage is moved for example into an intermediate orientation from which the connecting elements can be displaced into a second orientation. In the second orientation of the connecting elements, the blade support is in the safety position when the actuator is in the actuating position. The intermediate orientation is for example unstable. Unstable orientation in the meaning of the invention means that no forces that force the blade support into a cutting position are transmittable from the actuating element via the connecting linkage to the blade support. In the second orientation, a second spacing is formed between the first pivot and the second pivot. 
     The first spacing for example is such that, with the actuator being in the actuating position, the blade support is moved into the cutting position. The second spacing, for example is such that, when the actuator is in the actuating position, the blade support is in the safety position. 
     The connecting linkage can be for example in the first orientation when the blade support is in the first cutting position. When the blade support is moved by a cutting force from the first cutting position into the second cutting position, for is example the connecting linkage is moved from the first orientation into the intermediate orientation. The blade support is biased by a biasing or reset element into the safety position. In the intermediate orientation of the connecting linkage, the blade support can move back for example into the safety position once the cutting force no longer holds the blade support in the cutting position. This way, the connecting linkage moves for example into the second orientation. 
     According to a first embodiment, the connecting linkage can comprise a first connecting element and a second connecting element, the first connecting element and the second connecting element being connected by a third pivot. When the first and the second connecting elements are in the first orientation, the degree of freedom of the connecting elements can be limited such that the first and the second pivots are spaced at the first spacing from each other. During movement from the first orientation into the second orientation or into the intermediate orientation, the connecting linkage can be moved past a position in which the first pivot, the second pivot and the third pivot are on a straight line. 
     According to a further embodiment, the first and/or the second connecting element can be formed by a control arm. The control arm is for example a rod. Due to the rod shape, the first connecting element and the second connecting element can be very close to each other in the first orientation and can be spaced far apart in the second orientation. 
     A center axis of the first connecting element and a center axis of the second connecting element can form, according to a further embodiment, an obtuse angle in the first cutting position and a reflex angle can be formed in the second cutting position. During movement from the first cutting position into the second cutting position, the connecting linkage passes through an elongated orientation in which the first, the second and the third pivot lie on a straight line. 
     According to a further configuration of the invention, the blade support is forced by a reset force into the safety position. Once the blade support is no longer held in the cutting position by the actuator, the blade support is moved back into the safety position by the reset force. This can be the case for example when after reaching the second cutting position of the blade support, the connecting linkage has been moved into the second orientation in which, with the actuator actuated, a return movement of the blade support is possible. 
     According to a further configuration of the invention, the actuator is biased into the starting position by a biasing or reset force. Once the actuator is no longer actuated by the user, it moves automatically into the starting position. Elements that are kinematically connected to the actuator and do not belong to the actuator can also be biased into a predetermined position by the reset force. 
     According to a further embodiment according to the invention, at least one connecting element is associated with a multiarm lever having at least one first lever arm and one second lever arm. For example the first lever arm can form the first connecting element. The second lever arm can form for example a control element via which the lever is forced into a predetermined position or is moved into a predetermined position. 
     According to a further configuration of the invention, the blade support has first control means that form a first control surface, the first control surface interacting with a second control surface that is associated with the connecting linkage. During movement of the blade support, the first control surface can interact with the second control surface in such a manner that the connecting linkage is moved into a predetermined position. For example during movement of the blade support from the first cutting position into the second cutting position, the first control surface can interact with the second control surface in such a manner that the connecting linkage is moved from the first orientation into the intermediate orientation. 
     According to a further embodiment, the blade support is mounted by a mounting device on the housing, the blade support is movable by the mounting device angularly and in a straight line. Due to this rotational and translational mounting, the blade support is able to perform a complex movement that includes rotational as well as translational elements. During movement from the safety position into the cutting position, the blade support can for example execute a purely translational movement. For example when moving from the first cutting position into the second cutting position, movement of the blade support is purely rotational. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       Further advantages of the knife are seen in an embodiment illustrated in the figures. In the figures: 
         FIG. 1   a  is a schematic partial section through the knife, the blade support being shown in a first safety position, the actuator in the starting position. and the connecting linkage in the first orientation, 
         FIG. 1   b  is a schematic view of the center axes of the connecting elements of the connecting linkage in the first orientation, 
         FIG. 2  shows the knife according to  FIG. 1 , the blade support being shown in a first cutting position, the actuator in the actuating position, and the connecting linkage in the first orientation, 
         FIG. 3   a  shows the knife according to  FIG. 1 , the blade support being in a second cutting position, the actuator in an actuating position, and the connecting linkage in an intermediate orientation, 
         FIG. 3   b  shows the connecting elements as in  FIG. 1   b  in the intermediate orientation, 
         FIG. 4   a  shows the knife according to  FIG. 1 , the blade support being shown in a second safety position, the actuator in the actuating position, and the connecting linkage in a second orientation, and 
         FIG. 4   b  shows the connecting elements as in  FIG. 1   b  in the second orientation, 
         FIG. 5  shows the knife according to  FIG. 1 , the blade support being in the safety position, the actuator near the starting position. and the connecting linkage in the second position region, 
         FIG. 6  is a schematic longitudinal section through a second embodiment of the knife according to the invention, wherein a slide is in a rest position, 
         FIG. 7  is a schematic longitudinal section through the knife according to  FIG. 6  in another sectional plane, 
         FIG. 8  is a longitudinal sectional view of the knife in the cutting position, the slide being in the actuating position, 
         FIG. 9  is a longitudinal section through the knife according to  FIG. 8  in the cutting position, 
         FIG. 10  is a longitudinal section through the knife, the blade support being pivoted by a cutting force, 
         FIG. 11  is a longitudinal section through the knife according to  FIG. 10 , the blade support being pivoted by a cutting force, 
         FIG. 12  is a longitudinal section through the knife, the blade support being further pivoted by the cutting force, 
         FIG. 13  is a longitudinal section through the knife according to  FIG. 12 , the blade support being pivoted farther by the cutting force, 
         FIG. 14  is a longitudinal section through the knife, the blade support being moved relative to the slide into a second position and, with the handle actuated, is in the safety position, 
         FIG. 15  is a longitudinal section through the knife according to  FIG. 14 , the blade support being moved into the safety position, 
         FIG. 16  is a longitudinal section through a knife, the slide being between the actuating and the rest position, 
         FIG. 17  is a longitudinal section through the knife according to  FIG. 16 , 
         FIG. 18  is an exploded view of the knife, 
         FIG. 19  is an exploded view of the slide, the first control arm, the second control arm and the blade support, 
         FIG. 20  is a side view of the blade support and the slide in the primary position, the housing not being shown, 
         FIG. 21  is a view of the blade support and the slide from the opposite side as in  FIG. 20 , 
         FIG. 22  is a side view of the blade support and the slide in the second position, the housing not being shown, and 
         FIG. 23  is a view of an opposite side of the blade support and the slide with respect to the position according to  FIG. 22 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A knife in general is designated in the figures at  10 . Identical reference numbers in the different figures, also in case of additions such as, for example small letters, designate corresponding parts. 
     The knife  10  has a housing  11 . The housing  11  forms an interior  14 . The knife  10  has a blade support  12  to which a blade  13  is detachably fastened in an unillustrated manner. The blade support  12  is movable in the housing between a safety position shown in  FIGS. 1 ,  4  and  5  in which the blade  13  is retracted into the interior  14  of the housing  11  and cannot be touched by a user and the cutting position shown in  FIGS. 2 and 3  in which the blade  13  projects out of an opening  15  of the housing  11 . The mounting of the blade support  12  allows a translational movement relative to the housing  11  in the direction x 1 , x 2  as well as a rotational movement in the direction u 1 , u 2 . The translational movement and the rotational movement of the blade support  12  are limited. 
     An axle stub  20  on the blade support  12  engages in a groove  21  of the housing  11  and is pivotable about an axis a 1  and translationally movable in the directions x 1  and x 2 . The housing  11  and the blade support  12  form a pivot G 1 . The blade support  12  further has an extension  22  on whose the free end  23  a roller  24  is rotatably mounted. 
     The blade support  12  can be moved by an actuator  16  between the safety position and the cutting position. The actuator  16  has a connecting linkage  17  and an actuating element  19  that can be actuated by an unillustrated handle. The handle can be moved, for example by a pusher or a lever pivotal on the housing  11 , between the starting position shown in  FIG. 1  and the actuating position shown in  FIGS. 2 to 4 . 
     The blade support  12  has a fastening region  25 . At the fastening region  25 , the blade support  12  forms a pivot G 2  with a first control arm  26  of the connecting linkage  17 . In this manner, the control arm  26  is fixedly connected to the blade support  12  and is pivotable relative to the blade support  12  about a pivot axis a 2  in the direction s 1 , s 2 . 
     The first control arm  26  is connected at a pivot G 3  to a second control arm  27  of a two-arm lever  28  of the connecting linkage  17 . The second control arm  27  is pivotable relative to the first control arm  26  about a pivot axis a 3 . The two-arm lever  28  together with the actuating element  19  forms a pivot G 4 . The two-arm lever  28  is mounted to be pivotal relative to the actuating element  19  about a pivot axis a 4  in the direction w 1 , w 2 . 
     A fastening eye  30  on the second lever arm  29  is formed to which an end  31  of a spring  32  formed as a tension spring is fastened. An end  33  of the spring  32  is fastened at a formation  34  to the blade support  12 . On the actuating element  19 , a holding means  35  is formed to which an end  36  of a spring  37  is fastened. Another end  38  of the spring  37  is fastened to a holding means  39 . Bearing surfaces  40  of the actuating element  19  interact with guide surfaces  41  of the housing  11  that form a slotted guide for the actuating element  19 . The surfaces  41  guide the actuating element  19  during movement between the starting position and the actuating position. A rear stop  49  and a front stop  50  are provided on the housing  11  for the actuating element  19 . 
     In  FIG. 1 , the actuating element  19  of the actuator  16  is in the starting position. The blade support  12  is in a first safety position. The first control arm  26  has a center axis m 1  that connects the pivot axes a 2  and a 3  and is at an obtuse angle α 1  to a center axis m 2  of the second control arm  27 , which center axis m 2  extends between the pivot axes a 3  and a 4 . The pivot axis a 2  of the pivot G 2  has a spacing L 1  from the pivot axis a 4  of the pivot G 4 . 
     The connecting linkage  17  can be moved by the user against the spring-biasing force of the spring  37  from the starting position shown in  FIG. 1  into the actuating position shown in  FIG. 2 . During movement of the connecting linkage  17  into the actuating position, the blade support  12  is moved into a first cutting position (see  FIG. 2 ). During movement from the starting position into the actuating position, the angle α 1  between the first control arm  26  and the second control arm  27  remains unchanged. Moreover, the spacing L 1  remains unchanged. 
     The axle stub  20  of the blade support  12  is moved from an end  42  of the groove  21  to an end  43 . While the axle stub  20  rests in the starting position against a stop surface  44  of the groove  21 , the axle stub  20  comes in contact in the actuating position with a stop surface  45  of the groove  21 . 
     In the position of the connecting linkage  17  according to  FIGS. 1 and 2 , a moment in the direction w 1  is generated in the two-arm lever  28  by the spring  32 . The first control arm  26  connected via the pivot G 3  to the second control arm  27  is pivoted about the pivot axis a 2  in the direction s 1  and holds an outer surface  46  of the extension  22  on an inner surface  47  of the housing. 
     If, according to  FIG. 2 , a sufficient cutting force F acts on the blade  13 , the blade support  12  is pivoted against the biasing force of the spring  32  about the pivot axis a 1  from the first cutting position shown in  FIG. 2  into the second cutting position shown in  FIG. 3 . The rear end of the extension provided with the roller  24  exerts a force on the first control arm  26  and pivots the first control arm  26  about the pivot axis a 2  in the direction s 2  into the position according to  FIG. 3 . In the position according to  FIG. 3 , the center axes m 1  and m 2  form a reflex angle α 2 . 
     The blade  13  remains in the position according to  FIG. 3  as long as the cutting force is at least as high as the spring force of the spring  32 . As soon as the spring force becomes greater than the cutting force that holds the blade support  12  against the spring force of the spring  32  in the second cutting position, the blade support  12  is retracted by the spring  32  into the safety position shown in  FIG. 4 , the control arm  26  pivoting about the pivot axis a 2  in the direction s 2  and the control arm  27  pivoting about the pivot axis a 4  in the direction w 2 . 
     In the position according to  FIG. 4 , an angle α 3  is formed between the first control arm  26  and the second control arm  27 . The pivot axis a 2  and the pivot axis a 4  are spaced at a spacing L 2  from each other at which spacing the blade support  12  is in the second safety position when the actuating element  19  is in the actuating position according to  FIG. 4 . 
     Once the actuator  16  is not actuated anymore by the user, the actuating element  19  is moved back by the spring  37  in the direction x 2  (see  FIG. 5 ). During movement of the actuating element  19  in the direction x 2 , the control arm  27  pivots about the pivot axis a 4  in the direction w 1  and the control arm  26  pivots about the pivot axis a 2  in the direction s 1 . The spring  32  is tensioned. The blade support  12  moves also in the direction x 2  until the axle stub  20  rests against the stop surface  44  of the groove  21 . 
     When moving the actuating element  19  further in the direction x 2  until a contact surface  48  of the actuating element  19  rests against an inner surface  49  of the housing, the spring  32  is further tensioned, and the spring pivots the two-arm lever  28  via the second lever arm  29  in the direction w 1  into the position shown in  FIG. 1 . 
     A second embodiment of the knife is shown in  FIGS. 6 to 21  and is generally designated by the reference number  110 . 
     With respect to the exploded illustration of the knife according to  FIG. 18 , the knife has a housing  111  with a first housing shell  111   a  and a second housing shell  111   b . Furthermore, a third housing shell  111   c  and a fourth housing shell  111   d  are provided that can be fastened to the subassembly of the first housing shell  111   a  and the second housing shell  111   b . The fourth housing shell  111   d  is provided with an opening  115  that, in the assembled state of the knife  110 , forms the opening through which the blade passes. 
     A slide  118  is movably received in an interior  114  of the housing  111 . A blade support  112  is fastened on the slide  118  by a connecting linkage. The slide  118  and a first control arm  119  of the connecting device form a first pivot G 5 . The first control arm  119  is connected by a second pivot G 6  to a second control arm  120  that is likewise associated with the connecting linkage. The second control arm  120  and the blade support  112  form a third pivot G 7 . 
     According to  FIG. 20 , the slide  118  has an upper sliding surface  123  that interacts with a housing surface  171 . A slot  125  is formed in the slide  118 . At an end, the slot  125  has a shoulder  126  with a holding surface  127 . In order to form the first pivot G 5 , a recess  128  is provided in the slide  118 . An actuating surface  129  is formed at an end of the slide  118 . A fastening hook  130  is formed on the slide  118  and serves for fastening a spring  121 . 
     A handle  117  has a rail  131  with a grip surface  132 . An end of the rail  131  is formed with an extension  133 . The extension  133  has a shoulder  134  with a holding surface  135  as well as an actuating surface  124 . Another end of the rail  131  is provided with a recess  136  for forming a pivot G 8 . 
     The blade support  112  has a recess  137  that together with a pin  138  of the second control arm  120  forms the third pivot G 7 . A holding seat  140  of the blade support  112  serves for detachably fastening a blade  141 . A flap  142  is pivotably fastened on the blade support  112 . According to  FIG. 18 , the blade  141  is retained between a surface  143  of the holding seat  140  and a surface of the flap  142 . The flap  142  is fastened to the blade support  112  and is pivotable about a pivot axis a 9 . 
     A pin  138  of the second control arm  120  together with the recess  137  of the blade support  112  forms the third pivot G, having a pivot axis a 7 . A fastening extension  139  that is eccentric to the pivot axis a 7  of the third pivot G, is formed on the pin  138  and a spring  122  can be fastened thereto. A pin  145  of the second control arm  120  together with a recess  146  of the first control arm  119  forms the second pivot G 6  having a pivot axis a 6 . Moreover, a pin  147  is formed on the control arm  119 , and the pin together with the recess  128  of the slide  118  form the first pivot G 5  having a pivot axis a 5 . Furthermore, the control arm  119  has a control surface  148  that is formed on a projection  149 . 
     The first housing shell  111   a  has a pin  150  that has a first region  151  and a second region  152 . In the assembled state of the knife  110 , the first region  151  projects into a recess  136  of the handle  117  and a recess  161  of the fourth housing shell  111   d . At a rear end of the first housing shell  111   a , a nose  153  having a contact surface  154  is formed that interacts with the projection  149 . Furthermore, a fastening pin  155  for fastening the spring  122  and a fastening pin  156  for fastening the spring  121  are formed on the first housing shell  111   a.    
     The second housing shell  111   b  is provided with a recess  157  into which projects in the assembled state of the knife  110  the region  152  to form the fourth pivot G 8  having a pivot axis a 8 . Furthermore, the housing shells  111   a  and  111   b  have a fastening structure  158  that corresponds with a fastening structure  159  on an inner side  159  of the third housing shell  111   c  so as to fasten the third housing shell  111   c  to the unit consisting of first housing shell  111   a  and second housing shell  111   b . The fourth housing shell  111   d  has a lug  160  having the recess  161 . 
     For better clarity, the positions of the blade support  112  relative the slide  118  are shown in  FIGS. 20 to 23  without housing  111 . The pin  147  of the first control arm  119  penetrates the recess  128  of the slide  118  and is pivotal therein. The pin  138  extends into the slot  125  and is guided in the slot  125 . The pin  138  is pivoted on the blade support  112 . 
     The blade support  112  can be moved between a primary position shown for example in  FIGS. 20 and 21  and a secondary position shown for example in  FIGS. 22 and 23 . In the primary position, an imaginary first straight line  162  connecting the first pivot G 5  and the second pivot G 6  and an imaginary second straight line  163  connecting the second pivot G 6  and the third pivot G 7  form an angle α 3 . In the secondary position, the first straight line  162  and the second straight line  163  form an angle α 4 . During movement from the primary position into the secondary position, the first straight line  162  and the second straight line  163  move past a dead point position in which the first straight line  162  and the second straight line  163  form an angle α=180°. 
       FIGS. 6 to 17  show the function of the knife  110 . According to  FIGS. 6 and 7 , the slide  118  is in a rest position. By pivoting the handle  117  about the pivot axis a 8  in the direction t 2  out of the position shown in  FIGS. 6 and 7 , the slide  118  can be moved from the rest position into the actuating position shown in  FIGS. 8 and 9 . With decreasing force on the handle  117 , the slide  118  is moved by the first spring  121  back into the rest position, and, directed by the interacting surfaces  124  and  129 , the handle  117  is moved in the direction 
     As long as the handle  117  is not actuated, the slide  118  is in the rest position and the blade  141  is in the safety position in the interior  114 . The blade support  112  is in the primary position relative to the slide  118  and is forced by the spring  122  back into the rest position. An arm  164  of the second control arm  120  is supported on a surface  165  of the slide  118 . 
     When the handle  117  according to  FIGS. 8 and 9  is actuated, the slide  118  is in the actuating position. The blade support  112  keeps the primary position relative to the slide  118  so that the blade  141  moves out of the front opening  115  of the housing  111 . The position of the blade support  112  according to  FIGS. 8 and 9  is designated as first cutting position. 
     Due to the small lever arm of the spring force of the spring  122 , the eccentric arrangement of the spring  122  on the fastening extension  130  is not relevant in the first cutting position. However, in the second cutting position, the lever arm is greater and forces the blade support  112  into the secondary position. 
     By a force that acts through the cut on the blade  141 , the blade support  112  is pivoted, wherein a pivot contour  170  of the blade support  112  interacts with the housing surface  171  and forms a pivot point. During the pivoting process of the blade support  112 , a shoulder surface  172  of the second control arm  120  is brought in abutment with a holding surface  127  of the slide  118  (see  FIGS. 10 and 11 ) so as to avoid unintended movement of the blade support  112  into the safety position during the cutting process. The first straight line  162  moves relative to the second straight line  163  past a dead point position (see  FIGS. 10 and 11 ). In doing so, the above-described angular change between the first straight line  162  and the second straight line  163  takes place. This position of the blade support  112  is designated as second cutting position. 
     Only when the cutting force on the blade  141  decreases, can the shoulder surface  172  move out of engagement with the holding surface  127 , so that the blade support  112  can be moved by the spring  122  into the secondary position. The secondary position is shown in  FIGS. 14 and 15 . 
     In the secondary position, the blade  113  is in the safety position although the handle  117  according to  FIGS. 14 and 15  is actuated and the slide  118  is in the actuating position. In the safety position, the blade  141  is in the interior  114  so that the user cannot be injured by the blade  141 . 
     With decreasing force acting on the handle  117 , the handle  117  is indirectly moved by the slide  118  into the non-actuated position (see  FIGS. 16 and 17 ). The slide  118  is moved by the first spring  121  back into the rest position while the backward movement of the blade support  112  is prevented by an abutment  166  against which an abutment surface  167  of the blade support  112  according to  FIGS. 16 and 17  rests. During the further backward movement of the slide  118 , the contact surface  154  of a nose  153  formed on the housing  111  interacts with a control surface  148  of a control cam  140  of the first control arm  119 . Due to the interaction of the nose  153  and the control cam  149  during backward movement, the first control arm  119  and the second control arm  120  are pivoted until the angle α 3  is formed again between the first straight line and the second straight line and the blade support  112  is moved relative to the slide  118  into the primary position (see  FIGS. 6 and 7 ). 
     It should also be mentioned that as an alternative to the handle  117 , a pusher actuatable from outside the housing can be provided so as to move the slide  118  between the rest position and the actuating position. 
     Furthermore, it should be mentioned that the blade support  112  is fixedly connected to the slide  118  by means of the connecting linkage.