Abstract:
A powered surgical handpiece ( 20 ) designed to actuate cutting accessories ( 22 ) such as those used to perform endoscopic surgery. The handpiece includes a housing ( 24 ) that contains a motor ( 26 ). The motor is within its own housing ( 46 ). A motor rotor ( 88 ) extends out of the motor housing ( 46 ) and engages a gear reduction assembly ( 76 ). The gear reduction assembly includes a planetary gear assembly for which the motor rotor ( 88 ) is the sun gear. The motor housing ( 46 ) is formed to have integral therewith a ring gear ( 96 ) that is located around the portion of the motor rotor that extends out of the motor housing. There is a valve ( 44 ) for regulating suction flow through the handpiece. The valve sits in a valve bore ( 110 ) that is closed at one end. There is also coupling assembly ( 28 ) for releasably holding the cutting accessory to the housing so that the cutting accessory engages with the gear assembly. The components forming the coupling assembly are disassembled from each other to facilitate maintenance of the handpiece.

Description:
FIELD OF THE INVENTION 
     This invention is related generally to a powered handpiece useful for performing endoscopic surgical procedures and, more particularly, to a handpiece that is economic to assemble, reliable and easy to maintain. 
     BACKGROUND OF THE INVENTION 
     Endoscopic surgical procedures are routinely performed in order to accomplish various surgical tasks. In an endoscopic surgical procedure, small incisions, called portals, are made into the patient. An endoscope, which is a device that allows medical personnel to view the surgical site, in inserted in one of the portals. Surgical instruments used to perform a specific surgical task are inserted into other of the portals. The surgeon views the surgical site through the endoscope to determine how to manipulate the surgical instruments in order to accomplish the surgical procedure. An advantage of performing endoscopic surgery is that since the portions of the body that are cut open are minimized, the portions of the body that need to heal after surgery are likewise reduced. Moreover, during an endoscopic surgical procedure, only a relatively small portions of the patient&#39;s internal organs and tissue are exposed to the open environment. This minimal opening of the patient&#39;s body lessens the extent to which a patient&#39;s organs and tissue are open to infection. 
     The ability to perform endoscopic surgery has been enhanced by the development of powered surgical tools especially designed to perform endoscopic surgical procedures. One such tool, for example, is sold by the Applicant&#39;s Assignee under the trademark HUMMER II. This tool is in form of a cylindrical handpiece designed to be held in the hand of the surgeon. Internal to the handpiece there is a motor. A front end of the handpiece is provided with a coupling assembly for releasably holding a cutting accessory. The types of cutting accessories that are attached to these handpiece include edgers, resectors, planers and burrs. Integral with the motor and coupling assembly is a means for transmitting the rotary power developed by the motor to the cutting accessory. 
     The handpiece also has a suction conduit. This is because, in an endoscopic surgical procedure, irrigating fluid is introduced into the surgical site. This fluid serves as a transport media for removing tissue and debris from the surgical site. In order to remove the irrigating fluid, and the material in the fluid, a suction path is provided through the cutting accessory and the handpiece. A suction pump is connected to the handpiece and provides the suction force for drawing the fluid and material away from the surgical site. In order to control the suction flow through the cutting accessory and the handpiece, the handpiece is provided with a manually operated valve. Thus, with a single handpiece, a surgeon both manipulates the cutting accessory and control the suction of material away from the surgical site. 
     While current powered surgical handpiece have proven to be useful tools, they are expensive to manufacture and can be difficult to maintain. This is because the handpiece, which is typically less than 14 cm long and less than 3 cm in diameter, must contain the motor, the coupling assembly, the suction conduit and the valve for controlling fluid flow through the suction conduit. Each of these subassemblies has a number of components that must cooperate with the complementary components of the handpiece. For example, the motor is often provided with a speed reducing/torque increasing planetary gear assembly. This assembly includes a fixed ring gear. Given the relatively small size of this ring gear, and the forces to which it is subjected, the gear is typically manufactured from stainless steel. Thus, this gear is provided as a stand-alone component internal to the handpiece. 
     Also, many handpieces are provided with lever-set suction valves for regulating fluid flow through the suction conduit. This type of valve includes a valve body that is rotatably fitted in the handpiece. Bosses extend outwardly from the opposed ends of the valve body through the handpiece. The bosses are connected to exposed levers on the handpiece that a surgeon pivots to set the valve. An advantage of this arrangement is that once assembled, the valve is essentially a single moving part. However, this assembly is formed out of numerous components. 
     Moreover, the coupling assemblies of many powered endoscopic surgical handpieces are likewise formed out of numerous components. This is because these assemblies typically must be designed to hold the rotating member of the cutting accessory to a complementary element integral with the gear train, hold a static outer shell of the cutting accessory in place, and provide a seal around the rotating member in order to ensure that there will be good suction flow through the rotating member. Currently, some of these coupling assemblies are constructed so that, once assembled, they are difficult, if not impossible, to disassemble. The difficulty associated with disassembling these coupling assemblies makes it difficult to perform maintenance on the handpieces with which they are associated. 
     Thus, collectively, having to provide the numerous components of the current endoscopic handpieces and that fact that some of their components cannot be readily disassembled makes it relatively expensive to both provide and maintain these handpieces. 
     SUMMARY OF THE INVENTION 
     This invention relates generally to a new powered surgical handpiece designed to perform endoscopic surgical procedures that is relatively economical to assemble and to maintain. More specifically, this handpiece includes a suction valve and a motor/gear assembly that both have few components and an easy to assemble coupling assembly. The suction valve, the motor/gear assembly and the coupling assembly of this invention are also relatively easy to disassemble. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is pointed out with particularity in the claims. The above and further advantages may be better understood by reference to the following description taken in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a perspective view of an endoscopic surgical handpiece of this invention that depicts a complementary cutting accessory secured to the handpiece; 
     FIG. 2 an exploded view of the components forming the handpiece; 
     FIG. 3 is a cross sectional view of the housing of the handpiece; 
     FIG. 4 is a cross sectional view depicting how the motor and gear assembly are fitted together; 
     FIG. 5 is a perspective of the motor housing; 
     FIG. 6 is a cross sectional view of the gear assembly; 
     FIG. 7 is a cross sectional view depicting how the suction valve is mounted to the handpiece housing; 
     FIG. 8 is a perspective of the suction valve; 
     FIG. 9 is a plane view of the receptacle; and 
     FIG. 10 is a cross sectional view of the cone sleeve and nose cap sub-assembly. 
    
    
     DETAILED DESCRIPTION 
     FIGS. 1 and 2 depict an endoscopic handpiece  20  of this invention and a complementary cutting accessory  22  attached to the handpiece. The handpiece  20  includes a generally cylindrical housing  24  that is open at both ends. A motor  26  is disposed inside the housing  24 . A coupling assembly  28  is mounted to the front end of the housing  24  for removably holding the cutting accessory  22  to the handpiece. 
     The cutting accessory  22  includes an a rotating hub (not illustrated) that engages the drive pin  79  of an output shaft  78  (FIG. 4) which is connected to the motor  26  as described hereinafter. The cutting accessory  22  includes a static outer hub  30  that surrounds the rotating hub that is held static by the coupling assembly  28 . A rotating cutting element, such as a planer  32 , extends forward from and rotates in unison with the rotating hub. An outer shell  34  extends forward from the outer hub  30  and surrounds the elongated shaft of the planer  32 . Irrigating fluid is introduced into the annular space between the inner wall of the outer shell  34  and the shaft of the planer  32  through an irrigation port  36  in an exposed section of the outer hub  30 . The shaft of the planer  32  is open around its cutting surfaces. A suction is drawn through the handpiece  20  and shaft of the planer  32  to remove irrigating fluid and the material entrained in the irrigating fluid. A more detailed discussion of the construction of the cutting accessory  22  is found in the Applicant&#39;s Assignee&#39;s U.S. Pat. No. 5,792,167, entitled SURGICAL IRRIGATION PUMP AND TOOL SYSTEM, issued Aug. 11, 1998, which is incorporated herein by reference. 
     As seen by reference to FIGS. 2 and 3, the handpiece housing  24  has a first, large diameter main bore  40  which is approximately 1.9 to 2.2 cm in diameter. The motor  26  is housed and the coupling assembly  28  is partially mounted in the main bore  40 . Extending parallel with and located above main bore  40 , handpiece housing  24  is formed to have a suction bore  42  that has a diameter of approximately 0.25 to 0.40 cm. A suction is drawn through suction bore  42 . As will be described hereinafter, this is the suction force that is applied through the cutting accessory  22  to draw irrigating fluid and debris away from the surgical site. Fluid flow through suction bore  42  is regulated by a valve  44  located in the front end of the handpiece housing  24 . (In this application “front”, “forward” and “distal” shall be understood to mean towards the cutting accessory  22 ). 
     As seen by FIG. 2, motor  26  is encased in a cylindrical motor housing  46  that is statically fitted in the main bore  40  of handpiece housing  24 . A seal retainer  48  is disposed behind the motor housing  46  in the main bore  40 . Two O-rings  50  are held between flat, annular flanges  52  integrally formed by the seal retainer  48 . The O-rings  50  provide a liquid tight barrier to prevent water vapor from penetrating towards the motor  26 . A plate-like connector housing  54  is disposed over the open rear end of handpiece housing  24 . Two screws  56 , which extend through openings in the connector housing  54 , (opening not identified) and engage into threaded bores  58  (depicted in phantom) in the rear of the handpiece housing  24  hold the connector housing  54  to the handpiece housing  24 . 
     A plug-like electrical connector  60  is threadedly secured into a complementary threaded bore  62  formed in the connector housing  54 . Electrical connector  60  provides the socket to which an external power cable  64  is removably attached to the handpiece  20 . Wires, (not illustrated), conduct the energization current from the cable  64  to the motor  26 . An O-ring  66  is fitted around the exposed, large diameter head of connector  60  and the reduced diameter threaded section. O-ring  66  provides a vapor barrier between the outside environment and the inside of the handpiece housing  24 . 
     A suction fitting  68  extends through an opening in the connector housing  54  and into the suction bore  42  of handpiece housing  20 . Complementary threading on the outer surface of fitting  68  and around the inside of the rear end of the suction bore hold the fitting to the handpiece housing  24 . It will be further noted from FIG. 7 that the outer surface of the handpiece housing  24  is formed with an elongated groove  70 . A removable irrigation line (not illustrated) is seated in groove. This irrigation line serves as the conduit through which irrigating fluid is flowed to the irrigation port  36  of the cutting accessory  22 . 
     As can be seen from FIGS. 2,  4  and  6 , the motor  26  is coupled directly a gear assembly  74 . Gear assembly  74  reduces the speed, increases the torque, of the rotational force produced by the motor  26 . Gear assembly  74  includes a gear housing  76  which is fitted over the front end of motor housing  46 . Output shaft  78  extends through gear housing  76 . The output shaft  78  is rotatably fitted in gear housing  76  by bearing assemblies  80 . The rear end of output shaft  78  is formed with a ring-shaped carrier plate  82 . Planet gears  84  are rotatably mounted to fixed axles  86  that extend rearwardly from carrier plate  82 . 
     The planet gears  84  are driven by a sun gear  88 . The sun gear  88  is actually the exposed end of the rotor shaft that extends out of motor housing  46 . Turning more specifically to FIGS. 4 and 5, it will be seen that the rotor, as well as the other parts of the motor  26 , are seated in the housing  46  so as to be spaced rearward from the front end, which is open. A circular bearing support  90  encloses the components forming the motor  26 . Bearing support  90  is formed with a center hole (not identified) through which the motor rotor projects. A retaining ring  91 , which is seated in a groove  92  formed in the inner wall of the motor housing  46 , holds bearing support  90  in place. 
     The drive pin  79 , extends perpendicularly through the front end of the output shaft  78 . The drive pin  79  holds the inner hub of the cutting accessory  22  to the output shaft  78  so that the inner tube of the cutting accessory and the shaft rotate in unison. 
     The forward portion of the inner wall of the motor housing  46 , the portion located forward of the retaining ring  91  to the front end of the housing, is formed to have teeth  96 . These are the teeth  96  which are engaged by the planet gears  84 . Thus, for the handpiece  20  of this invention, the motor housing  46  also serves as the static ring gear of the planetary gear assembly  74 . 
     The structure of the suction valve  44  and explanation of how the valve is mounted to the handpiece is now offered by reference to FIGS. 2,  3 ,  7  and  8 . Suction valve has a cylindrical valve body  102 . A through bore  104  extends diametrically through the valve body  102 . Extending coaxially away from valve body  102  is a valve stem  106 . Valve stem  106  has a diameter that is less than that of the valve body  102 . An L-shaped lever arm  108  is press-fit over the free end of valve stem  106 . Alternatively, the lever arm  108  is formed as single piece with the valve body  102 . It will be observed that the outer end of lever arm  108  is parallel with valve body  102 . The lever arm  108  is shaped so that the outer end thereof extends over the top of the handpiece housing  24 . It will further be noted that bottom surface of lever arm  108  is shaped to define a semi-circular groove  109 . The purpose of groove  109  will be explained below. 
     The handpiece housing  24  is formed to define a valve bore  110 , which is open at one end and closed at the other end, in which valve body  102  is seated. Valve bore  110  is located at the forward end of suction bore  42  and has a center axis that is perpendicular to the longitudinal axis of the suction bore  42 . Handpiece housing  24  is further formed to define a suction passage  112  which extends diagonally forward from the front end of valve bore  110  into the main bore  40 . When the suction valve  44  is in the open position, fluid is drawn out the cutting accessory  22 , through the front end of the main bore  40 , the suction passage  112  and the suction bore  42 . 
     The suction valve  44  is mounted to the handpiece by seating valve body  102  in valve bore  110 . Prior to this mounting, an O-ring  114  is seated over the exposed portion of the valve stem  106 . The O-ring  114  provides a seal around the valve body  102 . 
     The suction valve  44  is held in place by a pin  116  that extends through a pin bore  118  formed in front of the handpiece housing  24 . More specifically the pin  116  is seated in pin bore  118  and in a groove  120  formed in the surface of the housing  24  adjacent the bottom of valve lever arm  108 . When the pin  116  is seated in bore  118  and groove  120 , the portion of the pin that extends above groove  120  is seated in groove  109  formed in the lever arm  108 . Thus, the pin  116  locks the suction valve  44  in place. 
     As can be seen from FIGS. 2 and 3, the front of the handpiece housing  24  is further formed to have a reduced diameter neck  122 . Pin bore  118  extends rearwardly from the stepped surface between neck  122  and the rest of the housing  24 . A sleeve-like collar  124  is threadedly secured over neck  122 . Collar  124  covers the open end of pin bore  118  so as to hold the pin  116  in place. 
     The coupling assembly  28 , now described by FIGS. 2,  9  and  10 , includes a sleeve like receptacle  128  that is fitted in and extends out of neck  122  of housing  24 . The receptacle  128  is shaped to have a rear section  130  that is press fit in housing main bore  40 . The receptacle rear section  130  is shaped to have an oval through slot  132 . The oval through slot  132  provides for fluid communication from the inside of the receptacle to suction passage  112 . 
     The receptacle  128  is further formed to have an exposed section  134  that is integrally formed with and extends forward from rear section  130 . In the depicted version of the invention, the exposed section  134  of the receptacle  128  has an outer diameter less than the outer diameter of the rear section  130 . 
     Three metal ball bearings  136  are seated in separate holes  138  formed in the forward portion of the receptacle exposed section  134 . Receptacle  128  is shaped so that holes  138  have a cross-sectional profile equal to that of slice through a sphere. More particularly, the inner wall of receptacle  128  is formed so that the openings into holes  138  have a diameter less than the diameter of the ball bearings  136 . Thus, the ball bearings  136  cannot pass through holes  138  into the center of the receptacle  128 . 
     A cone sleeve  142  is fitted around the exposed end of receptacle  128  so as to surround bearings  136 . The cone sleeve  142  is formed so that the inner wall thereof has a frusto-conical section  144  that tapers inwardly from the front end of the sleeve. The inside of cone sleeve  142  is further formed so as to have an annular step  148  located rearward of holes  138  that extends away from receptacle  128 . The body of the cone sleeve  142 , which extends rearward from the outer perimeter of step  148 , projects into an annular interstitial space between inner wall of collar  124  and the outer wall of the receptacle exposed section  134 . 
     A nose cap  150  is threadedly secured to the distal end of the cone sleeve  142 . More specifically, nose cap  150  has a sleeve-like base  152 . The inner wall of base  152  is provided with threading that interlocks with complementary threading formed along the outer wall of cone sleeve  142 , (threading not identified). The nose cap  150  is further formed to have a lip  154  that extends inwardly towards the center axis of the handpiece  20  from the distal end of base  152 . The nose cap  150  is further dimensioned so that lip  154  is positioned to be located forward of the front end of the cone sleeve  142 , the forward-extending portion of the nose cap base  152  and lip  154  collectively define an annular space  156  the purpose of which will be explained below. 
     Coupling assembly  28  further includes a compression spring  158  that surrounds the receptacle exposed section  134 . The compression spring  158  extends between the outer front surface of the housing  24  that defines main bore  40  and cone sleeve step  148 . Compression spring  158  urges the cone sleeve  142  and nose cap  150  in the forward direction, towards the distal end of cutting accessory  22 . The spring-induced displacement of the cone sleeve  142  forces frusto-conical section  144  towards holes  138 . Thus, the frusto-conical section  144  of the cone sleeve  142  is forced against the bearings  136  to urge the bearings inwardly. This displacement of the bearings  136  holds the bearings in a complementary annular groove formed in static outer hub  30  of the cutting accessory  22  (groove not illustrated). Thus, compression spring  158 , cone sleeve  142  and bearings  136  cooperate to hold the cutting accessory  22  to the handpiece  20 . When the cutting accessory  22  is so coupled to the handpiece  20 , the coupling assembly is referred to as being in the run state. 
     The coupling accessory is released from the handpiece  20  by an individual pushing the cone sleeve  142  and nose cap  152  rearwardly, towards the proximal end of the handpiece. This action results in a like translation of annular space  156  so that the space essentially surrounds the outer surface of the receptacle  128  adjacent holes  138 . Once this space  156  is so defined around holes  138 , when an individual pulls outwardly on the cutting accessory, the bearings  136  are forced into the space. Thus, when the coupling assembly  28  is in this state, the bearings  136  do not offer any resistance to the removal or replacement of the cutting accessory  22 . When the coupling assembly  28  is in this state, it is referred to as being in the accessory load state. The coupling assembly  28  is returned to the run state by simply releasing the manual force used to force the cone sleeve  142  and nose cap  152  toward the rear end of the handpiece; spring  158  then urges the cone sleeve forward back to its run, position. 
     The motor  26  of this invention is designed so that its housing  46  not just houses the working components of the motor. Motor housing  46  also functions as the ring gear of the gear assembly  74  coupled to the motor. This eliminates the need to provide the handpiece  20  of this invention with a stand-alone ring gear. Thus, this invention eliminates both the expense and weight with having to provide this separate component. Moreover, still another benefit of this construction is that it eliminates the need to align a separate ring gear and the need to ensure that the separate ring gear stays in alignment. 
     The handpiece  20  of this invention is further constructed so that the suction valve  44  extends out of bore  110  that is only open at one side of the housing  24 . This arrangement eliminates the need to have to provide seals and other components for sealing a valve bore that is constructed as a through bore. Moreover, in addition to eliminating the costs associated with providing a second seal, this invention eliminates the malfunctions and repair costs associated with a second seal. 
     Furthermore, the coupling assembly  28  of this handpiece  20  can be readily disassembled by unscrewing the nose cap  152  and removing the ball bearings  136 . Once these components are separated from the handpiece, the cone sleeve and compression sleeve are easily removed. Thus, the coupling assembly of this invention can be easily taken apparent in order to facilitate the maintenance or repair of the handpiece. 
     Thus, the handpiece  20  of this invention is economical to assemble, is of reduced weight, and is easy to maintain. 
     It should be understood that the forgoing description has been limited to one particular version of this invention. It will be apparent that modifications can be made with the attainment of some or all of the advantages thereof. For instance, it should be recognized that not all versions of the handpiece of this invention have the described motor housing, suction valve or coupling assembly. Also, in other versions of the invention, means other than a pin may be employed to hold the suction valve  44  in position. For example, there may be times when it is desirable to employ a threaded set screw to hold the suction valve  44  in place. 
     Similarly, in some versions of the invention, the coupling assembly  28  may not be provided with the described ball bearings. For example, in some versions of the invention, it may be desirable to provide the coupling assembly with feet that are biased inwardly by the cone sleeve when the coupling assembly  28  is in the run state. Also, it may be desirable to provide the coupling assembly  28  with some sort of locking tab that holds the cone sleeve in the accessory load state. It may be desirable to provide this mechanism so that the medical personnel do not have to employ any mental or manual effort to hold the coupling assembly in the accessory load state while engaging in the replacement of the cutting accessories. 
     Therefore, it is the object of the appended claims to cover all such variations and modifications that come within the true spirit and scope of the invention.