Abstract:
A device ( 1 ) for generating tensile force and/or pressing force to thereby actuate at least one brake means ( 19 ) so as to brake or lock at least two caster wheels ( 11 ) of a mobile appliance includes at least one lever ( 5, 7 ) prepared for rotation thereof about a fulcrum ( 15 ); and at least one transmission means ( 9 ) disposed at the lever ( 5, 7 ) for transmitting the tensile force and/or pressing force generated during a rotation of the lever ( 5, 7 ) to the brake means ( 19 ). In addition, a mobile rack and device thereby equipped are specified.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a device for generating tensile force and/or pressing force to thereby actuate brake means. It moreover relates to a mobile rack and to a medical apparatus. 
     BACKGROUND 
     From practice, mobile racks and appliances having brakeable caster wheels are known. Such appliances include containers, pieces of furniture, shopping carts, pallet stackers, baby carriages, children&#39;s beds, trolleys, tool carts, etc. In connection with patients and hospitals, e.g., hospital beds, hospital gurneys, infusion stands, wheelchairs, treatment means such as dialysis apparatuses and the like having brakeable caster wheels are known. The casters allow to push or wheel the appliance thereby equipped, e.g., from one room to another room. At the destination, it may be secured against inadvertent rolling by braking the caster wheels. The brakes may be actuated either directly in the range of the caster wheel, for instance by means of a foot-operated lever, or indirectly by means of mechanisms for the transmission of a braking force, for which purpose cables or push rods are customarily employed. 
     The known mechanisms for the transmission of a braking force such as, e.g., those of U.S. Pat. No. 2,684,734, include a multiplicity of movable parts, whereby complexity of maintenance is increased. As a capability to centrally apply and release the braking force for all caster wheels simultaneously and with a same intensity is furthermore desirable, an adjustment of the braking force is altogether rather complex. 
     It is the object of the present invention to propose another device for braking or locking at least two caster wheels of a mobile appliance. In addition it is intended to specify a mobile rack equipped with such a device, as well as a medical apparatus having a like rack. 
     SUMMARY 
     The object of the present invention is achieved through a device for generating tensile force and/or pressing force as disclosed herein. 
     Thus, in accordance with an example embodiment of the present invention, a device for generating tensile force and/or pressing force to thereby actuate at least one brake means so as to brake or lock at least two caster wheels of a mobile appliance is being proposed. The device includes at least one lever that is prepared for being disposed or is disposed for rotation about a fulcrum. The device further includes at least one transmission means disposed at the lever, whereby tensile and/or pressing forces generated during a rotation of the lever may be transmitted to a brake means. The one or more brake means may be adapted for decelerating the appliance. In particular, the one or more brake means can be designed or embodied for effecting an increasing and/or an adjustable braking action or effect, respectively (in the sense of a braking action that is, in single cases, definable in a targeted manner) and/or a changing braking action. The brake means may advantageously, however, also have the form of locking brakes. Furthermore, the brake means can be designed or embodied as brakes having an additional locking option or mechanism, respectively. 
     The lever may be provided so as to rotate about a fixed fulcrum, for example by means of reception means for a pinion. Thereby, the fixed fulcrum can be fixed in the sense of stationarily fixed, relative to the mobile or movable or drivable, respectively, appliance that shall be braked or arrested by means of the device. 
     The lever may, however, also be provided so as to rotate or pivot about a virtual fulcrum. 
     The lever of the example device of the present invention may in particular have a horizontal position or at least be movable substantially in a horizontal plane during its use. This advantageously contributes to an example device of the present invention being designed with a low height. 
     The lever may in particular be adapted for mounting so as to centrally rotate on a stationary pinion of a mobile appliance or may be supported correspondingly. 
     The pinion may then be disposed on the bottom side of the mobile appliance equipped with the example device of the present invention. It may furthermore be disposed in a vertical downwardly orientation. 
     As the lever is devised for a rotating movement during its use, the example device of the present invention is not only extremely low and space-saving, but at the same time furnishes a simple, mechanical device that requires little maintenance or even no maintenance at all. Due to the possibility of providing on the lever several transmission means for transmitting a tensile force and/or a pressing force engendered during the rotation of the lever, it is advantageously possible to brake a plurality of brake means by using only one moving part, i.e., the lever. Thereby, the example device according to the present invention advantageously offers the possibility of enabling a common braking of arbitrarily combined wheels of a mobile appliance (e.g., both wheels of a common axis; only the front wheels; all rear wheels; arbitrary diagonal wheels etc.) by means of a simple constructional design. 
     As the example device of the present invention only comprises few parts and furthermore has a small size, the device of the invention is advantageously suited to be mounted subsequently for a simultaneous, central actuation of two or more caster wheel brake means even if no dedicated space was provided on the mobile appliance on the manufacturer&#39;s part (for instance, if the distance between the mobile appliance and the plane of a running support is low). 
     The example device of the present invention is furthermore advantageously characterized by the possibility of independently transmitting forces to two or more caster wheel brake means. Accordingly, even if one of the transmission means having the form, e.g., of cables should lose its function—such as due to breakage of one of the cables—the remaining brake means will remain fully functional. 
     The example device of the present invention is furthermore characterized by the possibilities of particularly cost-efficient realization and subsequent installation. 
     In one preferred example embodiment, a device having at least two levers is proposed, which levers are preferably adapted to rotate in opposite directions of rotation. If cable receptions are mounted, e.g., on the ends of each lever, this example embodiment allows an actuation in a same direction of two brake means of respective caster wheels having respective diagonally opposed or adjacent positions, irrespective of cable lengths. An adaptation to a particular application may be carried out in an extremely simple manner by correspondingly shortening the cables to the desired length. The present invention does, however, also encompass solutions where corresponding forces are transmitted to the brake means of the caster wheels not by cables or other pulling means but by means of push rods or other pushing means. In addition, combinations of cables or other pulling means and push rods or the like for the transmission of tensile and pressing forces to a respective one or several brake means are also encompassed by the present invention. 
     In a further preferred example embodiment of the device according to the invention, a plurality of levers, in particular all levers, are supported rotatably about one and the same fulcrum—in particular a fixed fulcrum. Using this design omits provision of several fulcrums that is of particular advantage in case of less space—not least optionally during mounting the example device according to the present invention at the mobile appliance. 
     When the fulcrum is fixed—for example, relative to the mobile appliance—or is provided there for being correspondingly fixedly arranged, this again reduces the effort required for the mechanical solution. Moreover, a fixed fulcrum needs less maintenance than a fulcrum being moved during use. 
     In a further preferred example embodiment of the device of the present invention, the latter includes at least one means for exerting thrust on at least one of the levers so as to cause the latter to rotate. Providing means for exerting thrust serves the purpose of a particularly user-friendly actuation of the device for obtaining a braking effect, for example by pressing down on a pedal. Conversion of the linear motion (thrust of the means) into a rotational motion (rotation of the lever) may be effected through the intermediary of a connection, in particular a rotatably designed connection, between the means for exerting thrust and the lever. Thrust may be applied to the lever, for instance, by means of a push rod or push member having a predetermined distance from its fulcrum, thereby causing the lever to rotate about its fulcrum. 
     In order to obtain rotary movements of several levers in opposite directions, the means for exerting thrust may drive the first lever in a first location and the second lever in a second location, wherein the common fulcrum of the two levers- or both fulcrums in cases of different fulcrums—may be situated in a range between the first and second locations. 
     The two levers may be disposed above and below each other, in which case they have cross-type or scissor-type relative positions. In order to further reduce the space occupied by them, they may also be arranged in a side-by-side or front-rear relationship in a vertical direction relative to a plane of a running support of the mobile appliance. The means for exerting thrust may consist of several parts. 
     In a further preferred example embodiment of the device according to the present invention, the two or more levers are provided rotatably about exactly one fixed fulcrum, respectively, or are provided for being rotated about exactly one fixed fulcrum. 
     In a further preferred example embodiment, the means for transmitting the generated tensile force and/or pressing force includes at least one compression spring. The compression spring may have a respective design and arrangement ensuring a homogeneous braking force for all the caster wheel brake means subject to braking by the device of the present invention. Fine or subsequent adjustment of the braking force may be left to the individual compression spring. To this end, the compression springs are preferably each provided on the cable reception of the lever. They may, however, also be provided on the side of the brake means of the caster wheels or in a central range of the transmission means (e.g., of the cable) between lever and brake means. 
     The object of the present invention is furthermore attained through a mobile rack, as well as by a medical apparatus. As the advantages obtainable by means of the example device of the present invention may hereby be obtained undiminished, express reference is now made to the above discussion thereof in order to avoid repetitions. 
     The present invention shall in the following be explained exemplarily by referring to the appended drawings. Same or identical reference numerals designate identical or similar components in the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematically simplified representation of an example device of the present invention for generating tensile force and/or pressing force in co-operation with four brakeable caster wheels in a simplified plan view. 
         FIG. 2  is a cross-sectional view of a caster wheel including one brake means. 
         FIG. 3  shows the example device of the invention of  FIG. 1  in an unbraked condition of the device. 
         FIG. 4  shows the example device of  FIG. 3  in a braked condition of the device. 
         FIG. 5  is a partial view of a brake pedal including latching means. 
         FIG. 6  is a detail view of a portion of an example device of the present invention. 
         FIG. 7  shows a portion of two levers of an example device of the present invention for generating a tensile and/or a pressing force. 
         FIG. 8  is a sectional view along line C-C of  FIG. 7 . 
         FIG. 9  shows an example dialysis apparatus including an example device of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a device of the invention  1  including a push rod  3  and two levers or cross-levers  5  and  7 , respectively. In the example of  FIG. 1 , the device  1  comprises four transmission means for transmitting the tensile force generated during a rotation of levers  5 ,  7 , which transmission means have the form of cables or brake cables  9  in  FIG. 1 . The brake cables  9  each extend from one end of a lever  5 ,  7  to a brake means (not represented in  FIG. 1 ) of caster wheels  11 . 
     The push rod  3  co-operates with levers  5 ,  7  via pinions  13  for rotatably coupling the push rod with the levers. The levers  5  and  7  include compression springs  14  which allow an automatic setting of the forces transmitted by means of the brake cables  9 , and thus of the braking effect. This setting of the braking force is also possible when using brake rods instead of brake cables. 
     When a braking force is passed over from the direction of the arrow marked F B  via the push rod  3  and the pinion  13  to the levers  5 ,  7 , the latter are rotated clockwise (lever  7 ) or counterclockwise (lever  5 ) about a pinion  15  representing their fulcrum. 
       FIG. 2  shows a sectional view of a caster wheel  11  having a tread  17  on which a brake lever  21  acts by pressure in the braking condition of the brake means  19  shown in  FIG. 2 . This pressure is transmitted by the brake cable  9  to the brake means  19  and is released when the tension on the brake cable  9  is released. Disengaging the brake lever  21  from the tread  17  may be favored or aided by means of a reset spring means disposed, e.g., within the brake means  19 . 
       FIG. 3  shows the device  1 , already shown in  FIG. 1 , having a pedal  23  for generating the push force to the push rod  3 . In the lower area of  FIG. 3  a sectional view along line A-A of the plan view of the upper area of  FIG. 3  is shown. An intermediate lever  25  (between pedal  23  and device  1 ) allows generating the push force in the direction represented by arrow F B  in  FIG. 1  relative to the device  1  by stepping down on the pedal  23 . The intermediate lever  25  allows the pedal  23  to attain the same starting position upon each actuation of the pedal  25  with the aid of a compression spring. 
       FIG. 4  shows the device  1  of  FIG. 3  in the braked condition. It is clearly visible that the levers  5 ,  7  now have an angled, scissor-type relative position and are exerting a tensile force on the brake cables  9  owing to their position relative to the pinion  15 . In a comparison of the cross-sectional views of  FIGS. 3 and 4  it is clearly visible how vertical pressure—for example through the foot on the brake pedal or pedal  23 —by means of the intermediate lever  25  moves the push rod  3  to the left-hand margin of  FIGS. 3 and 4 , resulting in the rotation of levers  5 ,  7  shown in  FIG. 4  owing to the pinion connections  13  between push rod and levers  5 ,  7 .  FIGS. 3 and 4  moreover show a bearing block  27  to which the pedal  23  is fastened. The bearing block  27  thus serves for mounting the push rod  3  and the pedal  23 . 
       FIG. 5  shows a latching means  29  including a latching element  31 , as well as a release tab  33  provided on the latching element  31 . Upon actuation of the pedal  23 , the latching element  31  is pushed against a pin. As a result of the inclined portion on the latching element  31 , the latching element rotates downwards. When the direction of rotation is changed, the transversely extending pin hooks into the latching element  31  to thus retain the braked position. The latching element  31  keeps the intermediate lever  25  in the braked position. Upon repeated actuation of the pedal  23 , the latching element  31  is again released, allowing the intermediate lever  25  to change its position. 
       FIG. 6  shows a cross-sectional view of a possible embodiment of the levers  5 ,  7  in the area of the pinion  15  representing their fulcrum. The pinion  15  is surrounded in portions thereof by a bearing sleeve  35  which ensures rotatability of, i.a., the levers  5 ,  7  relative to each other. In the representation of  FIG. 6 , the levers  5 ,  7  as well as other elements are spaced apart by means of spacer washers  37 . 
       FIG. 7  shows portions of levers  5 ,  7  in an embodiment of the device in accordance with the invention. The lever  5  of  FIG. 7  has an opening  39  for the passage of a pinion  13  in order to couple the lever  5  to a push rod  3  (not shown in  FIG. 7 ). 
       FIG. 8  shows a sectional view along line C-C of  FIG. 7 . The pinion  13  is mounted in a bearing sleeve  41  so as to allow a relative movement between pinion  13  and lever  5 . 
       FIG. 9  shows a dialysis apparatus  43  as one example of a medical apparatus including a device  1  of the invention in a perspective view obliquely from below.  FIG. 9  in particular shows elements which were already shown, inter alia, in  FIGS. 1 ,  3 ,  4 , and  5  and are discussed in the above discussion. In order to avoid repetitions, reference is therefore now made to the above discussion.