Abstract:
An actuator assembly is provided. The actuator assembly includes housing configured for operable engagement by a user, a trigger assembly operably supported on the housing, a gas cartridge releasably secured to the housing, a valve assembly mounted within the housing for controlling the flow of pressurized gas through the housing and a cylinder actuator operably operably connected to the valve assembly. The cylinder actuator includes a piston selectively extendable therefrom configured for depressing a plunger. The piston includes a head having an inlet surface disposed within an inlet chamber of the cylinder actuator and an outlet surface disposed within the outlet chamber of the cylinder actuator. The exposed surface area of the first surface is equal to the exposed surface of the second surface.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of and priority to U.S. Provisional Patent Application No. 61/681,706, filed Aug. 10, 2012, the entire disclosure of which is incorporated by reference herein. 
     
    
     BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The present disclosure relates to applicator assemblies for mixing and dispensing components. More particularly, the present disclosure relates to pneumatic actuator assemblies for controlling the flow of the components through and from the applicator assembly. 
         [0004]    2. Background of Related Art 
         [0005]    Applicator assemblies for mixing and dispensing components are known. Many of these applicator assemblies include component filled syringes for supplying the components to a mixing assembly. One such applicator assembly is disclosed in commonly own U.S. Pat. No. 8,033,483, the content of which is incorporated herein by reference in its entirety. In use, a clinician manually depresses the plungers of the syringes to supply the components to the mixing assembly. When the syringes are manually actuated, the rate at which the mixed components flow through and from the applicator assembly tends to vary. Since many mixing assemblies require a specific rate to operate effectively, the inconsistent flow rate can be problematic. 
         [0006]    To provide a more consistent flow of components through the applicator and to a surgical site, a surgeon may attach the applicator assembly to a powered actuator assembly configured for depressing the plungers of the syringes in a consistent and controlled manner. Some of these actuator assemblies are pneumatically-powered, such that when the assembly is actuated, e.g., a trigger is squeezed, compressed fluid, typically air from a gas cartridge, is supplied to a pneumatic cylinder actuator to cause a piston within the actuator to advance, thereby depressing the plungers of syringes in a consistent and controlled manner. 
         [0007]    Although pneumatically powered actuator assemblies are know, these assemblies experience a phenomenon known as “coasting.” As will be discussed in greater detail below, the result of coasting is a continued flow of material from the applicator assembly after the actuator assembly has been deactivated, i.e., upon release of the trigger. Coasting may result in gooping, dribbling or other unwanted flow of the mixed components. As will also be discussed in greater detail below, coasting also prevents defined stops or boundaries when applying the mixed components. 
         [0008]    Therefore, it would be beneficial to have an actuator assembly in which coasting is greatly reduced or eliminated altogether. 
       SUMMARY 
       [0009]    Accordingly, an actuator assembly is provided. The actuator assembly includes a housing configured for operable engagement by a user, a trigger assembly operably supported on the housing, a gas cartridge releasably secured to the housing, a valve housing mounted within the housing for controlling the flow of pressurized gas through the housing, and a cylinder actuator including a piston selectively extendable therefrom configured for depressing a plunger. The piston includes a head having an inlet surface disposed within an inlet chamber of the cylinder actuator and an outlet surface disposed within the outlet chamber of the cylinder actuator. The exposed surface area of the first surface is equal to the exposed surface of the second surface. 
         [0010]    In some embodiments, the piston includes a first shaft extending from the inlet surface of the head and a second shaft extending from the outlet surface of the head. The piston may include a shaft extending through the head such that the shaft extends from both the inlet and outlet surfaces of the head. Alternatively, the cylinder actuator includes first and second sections and the piston includes a first head disposed within the first section and a second head disposed within the second section. A first shaft extends between the first and second heads and second shaft extends from the second head, wherein an exposed surface area of the first head is equal to an exposed surface area of the second head. The housing may be configured for operable connection with an applicator assembly. The valve housing may include at least a first actuator valve and at least a first dispense on/off valve. The valve housing may further include at least one solenoid valve. In some embodiments, the housing includes a pencil grip. Alternatively, the housing may include a pistol grip. 
         [0011]    Also provided is a system including an applicator assembly and an actuator assembly. The applicator assembly includes at least one syringe having a plunger. The actuator assembly is configured for operable connection to the applicator assembly. The actuator assembly includes a cylinder actuator including a piston selectively extendable therefrom for depressing the plunger. The piston includes a head having an inlet surface disposed within an inlet chamber of the cylinder actuator and an outlet surface disposed within the outlet chamber of the cylinder actuator. The exposed surface area of the first surface and the second surface are equal. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and, together with a general description of the disclosure given above, and the detailed description of the embodiments given below, serve to explain the principles of the disclosure, wherein: 
           [0013]      FIG. 1  is a schematic diagram of an embodiment of an actuator assembly according to the present disclosure; 
           [0014]      FIG. 2  is a graph showing the flow rate of mixed components exiting an applicator assembly that is actuated by the actuator assembly schematically illustrated in of  FIG. 1 ; 
           [0015]      FIG. 3  is top view of a splatter sheet resulting from the flow of mixed components from the applicator assembly illustrated in the graph of  FIG. 2 ; 
           [0016]      FIG. 4  is a schematic diagram of an actuator assembly according to another embodiment of the present disclosure; 
           [0017]      FIG. 5  is a graph showing the flow rate of mixed components exiting an applicator assembly that is actuated by the actuator assembly schematically illustrated in  FIG. 4 ; 
           [0018]      FIG. 6  is a top view of a splatter sheet resulting from the flow of mixed components from the applicator assembly illustrated in the graph of  FIG. 5 ; 
           [0019]      FIG. 7  is a side view an actuator assembly according to another embodiment of the present disclosure schematically illustrating the components therein and including an applicator assembly operably attached thereto; 
           [0020]      FIG. 8  is side view of an actuator assembly according to yet another embodiment of the present disclosure schematically illustrating the components therein and including an applicator assembly operably attached thereto; and 
           [0021]      FIG. 9  is a schematic diagram of a cylinder actuator according to an embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    Embodiments of the presently disclosed applicator assembly will now be described in detail with reference to the drawings in which like reference numerals designate identical or corresponding elements in each of the several views. 
         [0023]    As discussed above, prior art pneumatically-powered actuator assemblies for use with applicator assemblies experience a phenomenon known as coasting. As will be discussed in further detail below, it has been determined that coasting occurs as a result of the reduced stopping force caused by the configuration of the piston head of the cylinder actuator. 
         [0024]    With reference to  FIG. 1 , a schematic diagram of a pneumatic actuator assembly according to a first embodiment of the present disclosure is shown generally as actuator assembly  1 . Actuator assembly  1  includes a gas supply  10 , a primary actuator charge valve  15 , a secondary actuator charge valve  20 , a single-ended actuator cylinder  25 , a dispense on/off valve  30 , an accumulator  35  and a solenoid valve  40 . Single-ended actuator cylinder  25  is configured to depress a plunger  62  ( FIG. 7 ) of an applicator assembly  50  ( FIG. 7 ). Actuator cylinder  25  includes a piston  26  having a head  28  and a shaft  29 . Actuator cylinder  25  defines a cavity  27 . Head  28  of piston  26  divides cavity  27  of actuator cylinder  25  into an inlet chamber  27   a  and an outlet chamber  27   b . Inlet chamber  27   a  includes an inlet  27   c  and outlet chamber  27   b  includes an outlet  27   d . Head  28  of piston  26  includes an inlet surface  28   a  disposed within inlet chamber  27   a  and an outlet surface  28   b  disposed within outlet chamber  27   b.    
         [0025]    The operation of actuator assembly  1  will now be described with reference to  FIG. 1 . Prior to use, gas supply  10  is loaded into actuator assembly  1 , if not already done so, and gas supply  10  is opened, i.e., a seal is punctured. Actuator cylinder  25  is then charged by opening primary actuator charge valve  15 . Once actuator cylinder  25  is fully charged, primary actuator charge valve  15  is closed. Secondary actuator charge valve  20  remains open after charging. When fully charged, the pressure within each of inlet and outlet chambers  27   a ,  27   b  of actuator cylinder  25  are equal, as are the forces acting on head  28  of piston  26 , therefore piston  26  is stationary. 
         [0026]    To actuate single-ended actuator cylinder  25 , dispense on/off valve  30  is opened, i.e., a trigger is squeezed. Opening of dispense on/off valve  30  permits pressurized gas to flow from outlet  27   d  in outlet chamber  27   b  of actuator cylinder  25  and pressurized gas to flow through inlet  27   c  of inlet chamber  27   a  of actuator cylinder  25  into inlet chamber  27   a . As the pressurized air flows from outlet chamber  27   b  and into inlet chamber  27   a , the difference in pressure acting on head  28  of piston  26  causes piston  26  to advance distally, in the direction of arrow “A”. Once dispense on/off valve  30  is closed, pressurized gas no longer flows from outlet chamber  27   b  through outlet  27   d , and the pressure within outlet chamber  27   b  and the pressure within inlet chamber  27   a  equalize to prevent further advancement of piston  26 . In this manner, piston  26  no longer depresses plunger  62  ( FIG. 7 ) of applicator assembly  50  ( FIG. 7 ), thereby stopping the flow of mixed components from the applicator assembly. 
         [0027]    With reference to the graph of  FIG. 2 , tests were conducted to measure the rate of the mixed components flowing from an applicator assembly while using actuator assembly  1 . During the test, actuator assembly  1  was actuated (started and stopped) four times (A, B, C, D). As seen in the graph of  FIG. 2 , the start of each actuation is represented by a substantially vertical line, which represents the nearly instantaneous flow of mixed components from the applicator assembly upon actuation of actuator assembly  1 . First actuation (A) was stopped at a time T 1 , second actuation (B) was stopped at a time T 2 , third actuation (C) was stopped at a time T 3 , and fourth actuation (D) was stopped at a time T 4 . As can be seen in the graph, the time at which the mixed components ceased flowing, i.e., attained a flow rate of zero (0), lags from the time each actuation was stopped. The amount of mixed component that is dispensed after actuator assembly  1  is stopped is indicated by the shaded areas of the graph and is a result of the coasting that occurs within single-ended actuator cylinder  25 . 
         [0028]    A spray sheet created during the testing of actuator assembly  1  is shown in  FIG. 3 . As can be seen, there is no distinct boundary at the stop of each actuation. Instead, after each stoppage, mixed component continued to flow from the applicator assembly. As discussed above, this overflow may result in gooping and/or dribbling of the mixed component, thereby increasing the difficulty of performing a clean application of the mixed components. 
         [0029]    Following testing, it was determined that the coasting in actuator assembly  1  occurs as a result of the reduced stopping force provided by outlet surface  28   b  of piston head  28 . Specifically, the exposed surface area of outlet surface  28   b , i.e., the area of piston head  28  disposed within outlet cavity  28   b , is less then the exposed surface area of inlet surface  28   a , i.e., the area of piston head  28  disposed within inlet cavity  28   a . As seen in  FIG. 1 , the difference in exposed surface areas is caused by the surface area of distal surface  28   b  that is covered by shaft  29 . The difference in exposed surface area of inlet and outlet surfaces  28   a ,  28   b  of head  28  of piston  26  results in there being less stopping force against outlet surface  28   b  subsequent to the closing of dispense on/off valve  30 . The time it takes for forces acting on inlet surface  28   a  and outlet surface  28   b  of piston head  28  to equalize is the lag time, or length of time mixed components continue to flow from the applicator assembly. 
         [0030]    Further testing found that by increasing the size of piston head  28  in relation to the diameter of shaft  29 , the effect of coasting could be greatly reduced. It was also determined that although included, there was not a need for accumulator  35  on the first actuation of actuator assembly  1 , as applicator assembly  50  ( FIG. 7 ) had not yet been used, and actuator assembly  1  could operate effectively without accumulator  35  in the subsequent actuations despite the any obstructions caused by previous use. In use, accumulator  35  provides actuator assembly  1  with an initial burst of speed during actuation. 
         [0031]    With reference now to  FIG. 4 , a schematic of an actuator assembly according to another embodiment of the present disclosure is shown generally as actuator assembly  100 . Actuator assembly  100  includes a gas supply  110 , a primary actuator charge valve  115 , a secondary actuator charge valve  120 , a double-ended actuator cylinder  125 , a first solenoid valve  130  and a dispense on/off valve  135 , and may optionally include an accumulator  40 , an accumulator on/off valve  45  and a solenoid valve  50 . Actuator assembly  100  is substantially similar to actuator assembly  1  and, therefore, will only be described as relates to the difference therebetween. Actuator assembly  100  includes a doubled-ended actuator cylinder  125  having a piston  126  including a head  128 , a first shaft  129   a  extending from an inlet surface  128   a  of head  128  and a second shaft  129   b  extending from an outlet surface  128   b  of head  128 . 
         [0032]    During operation of actuator assembly  100 , i.e., opening of dispense on/off valve  135 , piston  126  is moved distally within cavity  127  of actuator cylinder  125  due to the flow of pressurized gas into inlet chamber  127   a  and out of outlet chamber  127   b . Upon closing of dispense on/off valve  135 , the flow of pressurized gas into inlet chamber  127   a  and out of outlet chamber  127   b  is stopped. Because each of inlet and outlet surfaces  128   a ,  128   b  of head  128  include shaft  129   a ,  129   b , respectively, extending therefrom, the exposed surface areas of each of inlet and outlet surfaces  128   a ,  128   b  of head  128  are the same. As a result, the stopping force of outlet surface  128   b  is equal to the driving force against inlet surface  128   a , thereby ceasing the advancement of piston head  128  immediately or almost immediately upon closing of dispense on/off valve  135 . The equalization of the pressure within inlet and outlet chambers  127   a ,  127   b  may be further facilitated by solenoid valve  130  which is disposed between inlet  127   c  and outlet  127   d  of cylinder actuator  100  and is opened as dispense on/off valve  135  is closed. 
         [0033]    With reference to the graph in  FIG. 5 , tests similar to those discussed above with regards to actuator assembly  1  were conducted to measure the rate of the mixed components flowing from a similar applicator assembly while using actuator assembly  100 . During the tests, actuator assembly  100  was actuated (started and stopped) five times (A′, B′, C′, D′, E′). Similar to the graph of  FIG. 2 , the start of each actuation is represented by a substantially vertical line which represents the nearly instantaneous flow of mixed components from the applicator assembly upon actuation of actuator assembly  100 . First actuation (A′) was stopped at a time T 1 ′, second actuation (B′) was stopped at a time T 2 ′, third actuation (C′) was stopped at a time T 3 ′, fourth actuation (D′) was stopped at a time T 4 ′, and fifth actuation (E′) was stopped at a time T 5 ′. As can be seen in the graph, the time at which the mixed components ceased flowing, i.e., attained a flow rate of zero (0), occurs almost immediately upon deactivation of actuation assembly  100 . The amount of mixed component that is dispensed after actuator assembly  100 , as indicated by the area between the stop time and the line representing the flow rate, is nominal. 
         [0034]    As with the previous test, a spray sheet was created during the testing of actuator assembly  100 . As seen in the spray sheet shown in  FIG. 6 , there is a clear and distinct boundary at the stop of each actuation. As discussed above, the immediate or nearly immediate response achieved when using actuating the applicator assembly using actuation assembly  100  allows for a cleaner and more consistent application of mixed components. 
         [0035]    As seen in the graph of  FIG. 5 , the flow rate of the first actuation is greater then the flow rate of the subsequent actuations. This is a result of applicator assembly  50  being unused, and therefore without any obstruction. As noted above, while included, testing showed that accumulator  135  was not necessary to the effective operation of actuator assembly  100 . 
         [0036]    With reference to  FIG. 7 , an embodiment of an actuator assembly according to the aspects of the present disclosure is shown generally as actuator assembly  200 . Actuator assembly  200  includes a housing  202 , a trigger assembly  204 , a gas cartridge  210 , a valve housing  220  and a double-ended cylinder actuator  225 . As shown, housing  202  and trigger assembly  204  are in the form of a pistol grip. Although not shown, valve housing  220  includes one or more valves, i.e., solenoid, charge, dispense on/off, as discussed above for controlling the flow of pressurized gas through cylinder actuator  225 . Housing  202  of actuator assembly  200  is configured to operably receive an applicator assembly  50 . Applicator assembly  50  includes a source of components, i.e., syringes  60 , a manifold  70 , an elongated body  80  and a mixing/dispensing tip  90 . Plunger  62  of syringes  60  are disposed adjacent to distal end of outlet shaft  229   b  of piston (not shown) of double-ended actuator  225 . Syringes  60  and cylinder actuator  225  are arranged such that distal advancement of shaft  229   b  causes depression of plunger  62 . Although the aspects of the present disclosure are being described for use with applicator assembly  50 , it is envisioned that the aspects of the present disclosure may be modified for use with other applicator assemblies. 
         [0037]    As discussed above, because actuator assembly  200  utilizes a doubled ended cylinder actuator  225 , the surface areas of inlet and outlet surfaces (not shown) of head (not shown) of piston (not shown) are equal, therefore the equalization in pressure of inlet and outlet chambers (not shown) is nearly immediate. Thus, any coasting that was previously experienced as a result of differing exposed surface areas of the piston head is eliminated in actuator assembly  200 , as the exposed surface areas of the piston head in double-ended cylinder actuator  225  are the same. Actuator assembly  200  may also include a solenoid (not shown) disposed between the inlet and the outlet to further assist in the immediate equalization of the pressure in the inlet chamber and the outlet chamber. 
         [0038]    Turning to  FIG. 8 , another embodiment of an actuator assembly according to the present disclosure is shown generally as actuator assembly  300 . Actuator assembly  300  is substantially similar to actuator assembly  200  in form and function. Actuator assembly  300  includes a housing  302  and a trigger assembly  304  in the form of a pencil grip. Actuator assembly  300  further includes a gas cartridge  310 , a valve housing  320  and a double-ended cylinder actuator  325 . Applicator assembly  50  is operably connected to housing  302  of actuator assembly  300 . 
         [0039]    Either or both of actuator assemblies  200 ,  300  may include indicators (not shown) for indicating the amount of pressurized gas remaining in respective gas cartridges  210 ,  310 , the amount of component remaining in respective syringes  60 , the flow rate of the components from applicator assembly  50 , and/or any other various conditions that may be monitored during the use of actuator assemblies  200 ,  300 . 
         [0040]    As discussed above, the coasting within actuator assembly  1  was caused by the difference in surface area between the inlet surface and the outlet surface of the head of the piston. As also discussed above, one solution to this problem was addressed by adding a shaft to the inlet surface of the piston head such that each of the inlet and outlet surfaces of the head includes shaft  129   a  ( FIG. 4 ). Shaft  129   a  functions solely as a space holder to make equal the exposed surface areas of inlet surface  128   a  and outlet surface  128   b  of piston head  128 . 
         [0041]    With reference to  FIG. 9 , an alternative means of equalizing the exposed surface areas of inlet and outlet surface of a piston head is shown. Cylinder actuator  325  includes a first section  325   a  defining an inlet chamber  327   a  and a second section  325   b  defining an outlet chamber  327   b . A piston  328  includes a first piston head  328   a  received within inlet chamber  327   a  and a second piston head  328   b  received within outlet chamber  327   b . First and second piston heads  328   a ,  328   b  are connected by a shaft  329 . Shaft  329  may extend through second piston head  328   b , or instead a second shaft may extend distally from second piston head  328   b . Inlet and outlet chambers  327   a ,  327   b  and first and second piston head  328   a ,  328   b  are sized such that the surface area on the inlet side of first piston head  328   a  is equal to the exposed surface area on the outlet side of second piston head  328   b , i.e., the surface area of second piston head  328   b  minus the surface are covered by shaft  329 . In this manner, the coasting experienced in applicator assembly  50  as a result of cylinder actuator  325  during use of an actuator assembly including cylinder actuator  325  is eliminated or nearly eliminated. 
         [0042]    Although the illustrative embodiments of the present disclosure have been described herein with reference to the accompanying drawings, it is to be understood that the disclosure is not limited to those precise embodiments, and that various other changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the disclosure.