Patent Publication Number: US-7896201-B2

Title: Dispensing device

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a dispensing device for dispensing one component or multi-component masses contained in vessels having at least one piston rod and at least one forward feed mechanism which has at least a first clamping lever and at least a second clamping lever, each of which is arranged on the piston rod so as to be axially displaceable and swivelable in longitudinal direction of the dispensing device. At least two spring elements are provided which act upon the clamping levers, and the at least one first clamping lever can be actuated by forward feed means of a driving mechanism. 
     2. Description of the Prior Art 
     A dispensing device of the type mentioned above for dispensing one-component or multi-component masses contained in vessels, e.g., foil bags or cartridges, is known from DE 198 50 495 A1, for example. This dispensing device has two piston rods on which first clamping levers for advancing the piston rods and second clamping levers for locking the piston rod are arranged. In dispensing devices, clamping levers of this kind are also called clamping pieces. A driving mechanism that includes a motor, is actuated by an actuation switch, and an eccentric cam, which serves as a forward feed device for the first clamping levers, rotates. The outer contour of the eccentric cam cooperates with the first clamping levers. As a result of the rotation of the eccentric cam, the first clamping levers are swiveled in longitudinal direction of the dispensing device, thereby pushing the piston rods forward. The second clamping levers form retaining clamping pieces and prevent a movement of the piston rods in a direction opposite the dispensing direction during the dispensing process. The clamping levers can be disengaged from the piston rod by means of an unlocking lever so that the piston rods can be moved into an initial position in which, for example, a new vessel can be placed in the dispensing device. 
     In contrast to dispensing devices having a lever mechanism acting on the first clamping levers as forward feed means, a contemporary dispensing device ensures a substantially improved dispensing of a constant amount of the mass to be dispensed every time the actuating switch is actuated. 
     One-component masses or multi-component masses are costly so that when using masses of this kind in chemically anchored dowels, for instance, an exact metering over the entire dispensing path of the dispensing device is desirable. 
     SUMMARY OF THE INVENTION 
     It is the object of the invention to provide a dispensing device for dispensing one-component masses or multi-component masses contained in vessels which improves the constancy of the amount of mass to be dispensed along the entire dispensing path. 
     This and other objects of the present invention, which will become apparent hereinafter, are achieved, according to the invention, by providing a dispensing device in which the forward feed means comprises a first forward-feed element cooperating with the at least one first clamping lever and a second forward-feed element cooperating with the at least one second clamping lever. 
     The first forward feed element actuates the at least one first clamping lever and the second forward feed element actuates the at least one second clamping lever. The forward feed elements are advantageously arranged on a drive shaft of the driving mechanism. Owing to the fact that the forward feed means is formed of multiple parts, the individual forward feed elements can be constructed and arranged in accordance with their cooperation with the clamping levers. Further, the multi-part construction facilitates manufacture of the forward feed means. 
     When the driving mechanism is actuated, the forward feed means of the forward feed mechanism acts directly or indirectly on the clamping levers so that a uniform forward feed of the corresponding piston rod is ensured, and a constant amount of the mass to be pressed out is accordingly dispensed along the entire dispensing path. Retaining clamping pieces such as those required in prior art dispensing devices which cause a high degree of wear are no longer needed in the dispensing device according to the invention. 
     The at least one second clamping lever can advantageously be actuated alternately with the at least one first clamping lever. In other words, the clamping levers are actuated by the forward feed means successively in time. For this purpose, the forward feed means has, for example, correspondingly arranged projections or control cams. At the start of the actuation of the at least one second clamping lever, the at least one first clamping lever is in its foremost swiveling position. As the actuation continues, the at least one second clamping lever is displaced by the forward feed means, and the at least one first clamping lever is swiveled back into its initial position again by the spring action of the first spring element. In the meantime, however, the at least one second clamping lever is already engaged with the at least one piston rod and pushes the latter forward. The at least one first clamping lever locks the at least one piston rod in its initial position so that the latter cannot move counter to its forward feed direction. When the at least one second clamping lever is in its foremost swiveling position, the at least one first clamping lever is actuated by the forward feed means with every further actuation of the dispensing device, and the at least one second clamping lever is relieved and is swiveled into its initial position by the second spring element which acts on this clamping lever counter to the dispensing direction. However, the at least one clamping lever is now already engaging with the at least one piston rod and moves the latter forward. The at least one second clamping lever now locks the at least one piston rod in the initial position so that the latter cannot move counter to its forward feed direction. 
     This advantageous forward feed means of a dispensing device has a particularly uniform force curve and accordingly ensures that a constant amount is pressed out over the entire dispensing path each time the dispensing device is actuated. The dispensing mechanism in its entirety is loaded uniformly so that the dispensing device according to the invention has a long useful life and a low susceptibility to mixing problems when dispensing, for example, multi-component masses. 
     The first forward feed element preferably comprises a first eccentric cam which can be set in rotation and whose outer contour cooperates with the at least one first clamping lever, and the second forward feed element comprises a second eccentric cam which can be set in rotation and whose outer contour cooperates with the second clamping lever, the first eccentric cam and the second eccentric cam are arranged on a driveshaft of the driving mechanism, and the eccentricity of the second eccentric cam is arranged so as to be offset by 180° to the eccentricity of the first eccentric cam. When the driving mechanism is actuated, the eccentric cams rotate. When the first eccentric cam acting on the at least one first clamping lever reaches the top dead center, it is in its foremost swiveling position, wherein the second eccentric cam already acts upon the at least one second clamping lever. As the eccentric cams continue to rotate, the at least one second clamping lever is swiveled by the second eccentric cam in longitudinal direction of the dispensing device against the force of the second spring element until it is in its foremost swiveling position. In this position, the first eccentric cam already acts upon the at least one first clamping lever. This advantageous forward feed mechanism of a dispensing device has a uniform force curve and accordingly ensures in a particularly advantageous manner that a constant amount is pressed out over the entire dispensing path each time the dispensing device is actuated. The dispensing mechanism in its entirety is loaded uniformly in an advantageous manner. The at least one first clamping lever is actuated by the eccentric cams uniformly or advantageously alternately with the at east one second clamping lever. 
     The angle from the top dead center of the eccentric cams to the start of the slope of one of the eccentric cams is preferably 25° to 50°. In particular, this angle is advantageously 30° to 40°. When one of the eccentric cams reaches the top dead center, the corresponding clamping lever is fully loaded and in its foremost swiveling position. Each of the eccentric cams advantageously has an eccentric projection which projects away from a circular shape and passes continuously from the start of the slope into the top dead center. Alternatively, the eccentric cams have a circular shape in outline, and their center is arranged eccentric to or at an offset to the driveshaft at the desired degree of eccentricity. 
     The length of the forward feed path which is traveled by the at least one piston rod each time the actuating switch is actuated depends upon the eccentricity and the magnitude of this eccentricity must be selected correspondingly. Therefore, the eccentric cams advantageously have an eccentricity of 0.5 mm to 10 mm. It is particularly advantageous when the eccentric cams have an eccentricity of 1.5 mm to 4 mm. 
     The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiment, when read with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings show: 
         FIG. 1  a side partially cross-sectional view of a dispensing device according to the invention; 
         FIG. 2  a partial cross-sectional view along line II-II in  FIG. 1 ; and 
         FIG. 3  an enlarged plan view of a detail of eccentric cams as forward feed elements. 
     
    
    
     Basically, identical parts are provided with the same reference numerals in the drawings. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The dispensing device  11  shown in the drawings for dispensing multi-component masses contained in vessels such as foil bags or cartridges, for example, has a housing  12  with a handle  13  and a receptacle  14  for the vessel. A switch  15  by which a motor  16  can be switched on and off is provided at the handle  13 . 
     The dispensing device  11  further has two piston rods  21  of a forward feed mechanism  31 . A piston  22  for pressing out the multi-component mass is provided at the front end of the piston rods  21  in longitudinal direction L. The forward feed mechanism  31  has at each piston rod  21  a first clamping lever  32  and a second clamping lever  42  facing one another at an inclination to the longitudinal direction L. The clamping levers  32  and  42  are displaceable axially and swivelable in longitudinal direction L of the dispensing device  11 . A helical compression spring is provided at the piston rods  21  in each instance as first spring element  33  acting upon the first clamping lever  32  between a housing portion  17  of an inner housing  19  and the first clamping levers  32 . A helical compression spring is provided at the piston rods  21  in each instance between the first clamping lever  32  and the second clamping lever  42  as a second spring element  43  acting upon the second clamping lever  42 . 
     The first clamping lever  32  and the second clamping lever  42  can be acted upon alternately by forward feed means of the driving mechanism. The forward feed means comprise a first forward feed element  34  and a second forward feed element  44 . The first clamping levers  32  cooperate by means of a first forward feed plate  35  with the outer contour of a first eccentric cam  36  which can be set in rotation and which serves as the first forward feed element  34 . The second clamping levers  42  cooperate by means of a second forward feed plate  45  with the outer contour of a second eccentric cam  46  which can be set in rotation and which serves as the second forward feed element  44 . The two eccentric cams  36  and  46  are arranged on a driveshaft  18  driven by the motor  15 . A spacer sleeve is advantageously provided so that the eccentric cams  36  and  46  are arranged at a distance from one another. The eccentric cams  36  and  46  advantageously roll on a counter-pressure bearing (not shown) that is secured to the forward feed plates  35  and  45 , respectively, so that the friction between these elements is reduced and the usability of the dispensing device is substantially increased. 
     To guide the forward feed plate  35 , this forward feed plate  35  has two guide projections  39  which are arranged opposite one another and supported in recesses  20  in the inner housing  19 . To guide the forward feed plate  45 , the forward feed plate  45  also has two guide projections  49  which are arranged opposite one another and supported in recesses  20  in the inner housing  19 . 
     As is shown particularly in  FIG. 3 , the eccentricity E 2  of the second eccentric cam  46  is arranged so as to be offset by 180° relative to the eccentricity E 1  of the first eccentric cam  36  so that the second clamping levers  42  are actuated alternately with the first clamping levers  32 . The eccentricity E 1  and E 2  of the eccentric cams  36  and  46  determines the forward feed path S of the piston rods  21  and is 3 mm in this example. The angle W from the top dead center  37  to the start of the slope  38  of the first eccentric cam  36  and the angle V from the top dead center  47  to the start of the slope  48  of the first eccentric cam  46  is 35°, respectively. 
       FIG. 2  shows the forward feed mechanism  31  in the position of the forward feed elements  34  and  44 , respectively, in which the eccentric cam  46  moves the second clamping lever  42  into the foremost swiveling position and the first eccentric cam  36  is in the remote position so that the first clamping levers  32  are in their initial position. To illustrate operation, the dash-dot line  40  schematically shows the position of the first eccentric cam  36  in which after the corresponding rotation of the eccentric cams  36  and  46  the first eccentric cam  36  has moved the first clamping lever  32  into its foremost swiveling position and the second clamping lever  42  would be in its initial position. 
     Though the present invention was shown and described with references to the preferred embodiment, such is merely illustrative of the present invention and is not to be construed as a limitation thereof and various modifications of the present invention will be apparent to those skilled in the art. It is therefore not intended that the present invention be limited to the disclosed embodiment or details thereof, and the present invention includes all variations and/or alternative embodiments within the spirit and scope of the present invention as defined by the appended claims.