Abstract:
A medical/surgical irrigating handpiece with both a discharge line through which fluid is applied to the site and a suction line through which the discharge fluid is drawn away. The handpiece has a variable speed pulse pump. A single, variable-speed motor actuates the pump to regulate the pumping rate. Power to actuate the motor comes from a battery pack that remote to the handpiece. A control mechanism attached to the handpiece regulates the energization signal applied to the motor so as to regulate motor speed.

Description:
This is a continuation of Ser. No. 09/460,705, filed Dec. 14, 1999, now U.S. Pat. No. 6,746,419, which is a continuation of Ser. No. 09/009,657, filed Jan. 20, 1998, now U.S. Pat. No. 6,022,329, issued Feb. 8, 2000 which is a continuation of Ser. No. 08/559,133, filed Nov. 17, 1995, now U.S. Pat. No. 5,718,668, issued Feb. 17, 1998 which is a continuation of Ser. No. 08/049,144, filed Apr. 19, 1993, now U.S. Pat. No. 5,470,305. 

   FIELD OF THE INVENTION 
   This invention relates to a surgical irrigation with a built in pulsing pump. 
   BACKGROUND OF THE INVENTION 
   Grulke et al U.S. Pat. No. 5,046,486, assigned to the Assignee of the present invention, discloses a surgical pulsed irrigation handpiece which produces a pulsed irrigation liquid output capable of loosening and floating debris at a surgical site for subsequent removal (as by suction). This prior pulsed irrigation handpiece has been on the market for several years and has proved generally effective for its intended use and hence has been popular in the surgical community. 
   However, in a continuing effort to improve on existing devices of this general kind, the present invention has been developed. As compared to the above-mentioned prior device, a pulsed irrigation handpiece embodying the present invention is producible at lower cost, produces sharper liquid pulse transients (particularly the pulse “off” transient), requires no connection to any operating room power source (e.g. compressed air) or to an external pump, and instead is self-contained, requires only external connection to a irrigation liquid source (e.g. conventional irrigation liquid bag), provides better suction (when suction is required), is more compact, and is conveniently shaped to be held either as a pistol or a wand (by the handle or barrel). 
   Other objects, purposes and advantages of the invention will be apparent to those acquainted with apparatus as general kind upon reading the following description and inspecting the accompanying drawings. 
   SUMMARY OF THE INVENTION 
   A pulsed irrigation handpiece comprises pulsed irrigation liquid outlet means for applying liquid pulses to a surgical site, pump means reciprocatingly drivable for pumping pulses of irrigation liquid through said outlet means, powered drive means for reciprocatingly driving said pump means and housing means containing said pump means and drive means. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a pictorial view of a handpiece embodying the invention. 
       FIG. 2  is a laterally exploded pictorial view of the  FIG. 1  handpiece. 
       FIG. 3  is an enlarged elevational view of the  FIG. 1  handpiece with the leftward housing part removed. 
       FIG. 4  is a view similar to  FIG. 3  but with the suction hose removed, the left drive unit shell part removed and the drive unit exposed in central cross-section, such that  FIG. 4  approximates a central cross-sectional view of the  FIG. 1  handpiece. 
       FIG. 4A  is an enlarged fragment of  FIG. 4  detailing the rearward portion of the handle. 
       FIG. 4B  is an enlarged fragmentary pictorial view, taken from the front, of the electrical contact support posts seen in  FIG. 4A . 
       FIG. 4C  is an enlarged fragmentary exploded pictorial view of the electrical contacts, associated with the  FIG. 4B  posts and associated electrical conductors from the battery supply. 
       FIG. 5  is an enlarged, exploded, pictorial view of the drive unit of  FIG. 2 . 
       FIG. 6  is a sectional view substantially taken on the line  6 — 6  of  FIG. 5 , and provides a top view of the bottom drive unit shell part of  FIG. 5  (the rightward one of  FIG. 2 ) with the drive components removed to show the interior configuration of that shell part. 
       FIG. 7  is a sectional view substantially taken on the line  7 — 7  of  FIG. 5 , and provides a view similar to  FIG. 6  but showing the interior configuration of the other drive unit shell part (the upper one in  FIG. 5  and leftward one in  FIG. 2 ). 
       FIG. 8  is an enlarged central cross-sectional view of a tip unit usable with the handpiece of  FIG. 2  and showing same installed in a pump unit shown in central cross-section substantially as in  FIG. 4 . 
       FIG. 8A  is a reduced size, fragmentary, side elevational view of the apparatus of  FIG. 8 . 
       FIG. 8B  is a pictorial view of the apparatus of  FIG. 8A . 
       FIG. 9  is an end elevational view of the drive unit, taken from the right end in  FIGS. 2 and 3 . 
       FIG. 10  is a sectional view substantially taken on the line  10 — 10  of  FIG. 5  and showing the drive unit with one shell part (the left one in  FIG. 2  and top one in  FIG. 5 ) removed to show the motor and transmission. 
       FIG. 11  is an elevational view of the drive train substantially taken on the line  11 — 11  of  FIG. 10 . 
       FIG. 12  is a central cross-sectional view substantially taken on the line  12 — 12  of  FIG. 10 . 
       FIG. 13  is a fragmentary cross-sectional view substantially taken on the line  13 — 13  of  FIG. 10 . 
       FIG. 14  is a cross-sectional view substantially taken on the line  14 — 14  of  FIG. 10 . 
       FIG. 15  is a sectional view substantially taken on the line  15 — 15  of  FIG. 10 . 
       FIG. 16  is an exploded pictorial view of the pump unit of  FIG. 2  in an enlarged scale. 
       FIG. 17  is a front end elevational view of the pump unit of  FIG. 16  taken substantially from the left side of  FIGS. 2–4  and  16 . 
       FIG. 18  is a central cross-sectional view of the pump unit of  FIG. 17  taken substantially on the line  18 — 18  of  FIG. 17 . 
       FIG. 18A  is a fragment of  FIG. 18  showing the pump unit at the beginning of an intake stroke. 
       FIG. 18B  is a fragment of  FIG. 18  showing the pump nearing the end of an output pulse. 
       FIG. 18C  is a fragmentary enlargement of  FIG. 18  showing the valve member. 
       FIG. 19  is a fragmentary cross-sectional view showing the connection of the pump unit to the liquid supply hose. 
       FIG. 20  is a pictorial view of the electric power supply unit connected to the  FIG. 2  handpiece. 
       FIG. 21  is a left end view of the  FIG. 20  electric power supply unit. 
       FIG. 22  is an exploded pictorial view of the electric power supply unit of  FIG. 20 . 
       FIG. 22A  is an electrical schematic of the  FIG. 2  handpiece and  FIG. 20  electric power supply unit. 
       FIG. 23  is a central cross-sectional view taken substantially on the line  23 — 23  of  FIG. 22 . 
       FIG. 23A  is an enlarged fragmentary pictorial view of the support structure for battery contacts at the forward (left in  FIG. 23 ) end of the electric power supply casing. 
       FIG. 23B  is an enlarged pictorial view similar to  FIG. 23A  but showing the support structure for battery contacts at the rearward (rightward in  FIG. 23 ) end of the power supply casing. 
       FIG. 24  is a sectional view substantially taken on the line  24 — 24  of  FIG. 22  and showing the electric power supply unit with its top cover removed. 
       FIG. 25  is a sectional view substantially taken on the line  25 — 25  of  FIG. 22  and showing the underside of the cover of the power supply casing. 
       FIGS. 26 ,  27  and  28  are enlarged pictorial views of battery contacts of  FIG. 22 . 
       FIG. 29  is an enlarged fragmentary pictorial view of an embodiment of the liquid supply and electric wiring harness of the apparatus of  FIGS. 2 and 20  but showing a modification in the attachment of the electrical and liquid handling components. 
   

   In the following detailed discussion the terms “up”, “down”, “right” and “left”, and variations thereon, refer to structural elements in their positions in specified drawing figures. 
   DETAILED DESCRIPTION 
   A pulsed irrigation handpiece  10  ( FIGS. 1 and 2 ) embodying the invention comprises a hand-held housing  11  having a handle  12  and a barrel  13  which extends forward from the upper end of the handle  12  at about a 130° to 150° (here about 145°) angle thereto. 
   The housing  11  is hollow and, for convenience in assembling the handpiece  10 , is constructed as laterally opposed concave left and right housing parts  14  and  15  ( FIG. 2 ). The housing parts  14  and  15  are preferably molded rigid plastic elements held together rigidly by any convenient means, here comprising undercut snap fit tabs  16  protruding from the top and bottom edges of the right housing part  15  to snap over an interior edge flange (not shown) on the top and bottom edge of the left housing part  14 . If desired, precise registry together of the two housing parts can be assisted by laterally projecting pins  20  distributed along the edges of one housing part (here the left housing part  14 ) piloted in holes  21  ( FIG. 4 ) in the opposed edges of the other housing part (here  15 ). Upon completion of assembly of the handpiece  10 , the two housing parts  14  and  15  may be adhesively bonded together. The handpiece is intended to be a disposable item and therefore access to the interior of the housing for purposes of repair is not needed. 
   Drive Unit 
   The drive unit  25  ( FIGS. 2–15 ) is self contained in its own shell  26  ( FIG. 2 ). For convenience in assembly, the shell  26  comprises two opposed concave shell parts  30  and  31  respectively disposed to the left and right in  FIG. 2 . The shell parts  30  and  31  are preferably of rigid molded plastics material. When the drive unit  25  has been assembled, as in  FIGS. 2 and 9 , the shell parts  30  and  31  are held fixedly together by any convenient means, here by resilient snap connection of generally U-shaped clips  32 , molded in spaced relation along the perimeter edge of the shell part  31  which overlap the perimeter edge of the shell part  30  and snap over tabs  33  protruding therefrom, as seen in  FIGS. 5–7 . Precise location of the shell parts  30  and  31  with respect to each other is assisted by locator pins  34  fixedly protruding from the shell part  31  and holes  35  in the opposed portions of the shell part  30 . 
   A single conventional DC energizable electric motor  36  ( FIGS. 4 and 5 ) is snugly housed in the space between the left and right ( FIG. 2 ) shell parts at the rear (left in  FIGS. 5–7 ,  10  and  12 ) thereof. The motor  36  is snugly axially located between the rear end wall and a transverse internal bulkhead  41  of the shell  26  ( FIGS. 5–7 ,  10  and  12 ). The rear end wall  40  and bulkhead  41  have opposed parts in the left and right shell parts  30  and  31 , as seen in  FIGS. 6 and 7 . 
   Rear and front bosses  42  and  43  respectively extend rearward and forward from the cylindrical casing  44  of the motor  36 , as seen in  FIGS. 10 and 12 ), and are supported in corresponding coaxial recesses  45  and  46  in the rear end wall  40  and bulkhead  41  respectively, so as to support the motor casing  44  with respect to the shell  26 . A flat  47  on the rear boss  42  ( FIG. 9 ) co-acts with a corresponding flat in the surrounding recess  45  to prevent rotation of the motor casing  44  with respect to the shell parts  30  and  31 , such that the motor  36  is antirotationally fixed within the shell  26 . 
   The drive unit  25  further includes a transmission  50  ( FIG. 5 ) coaxial with and forward of the motor  36 . The transmission includes a reciprocating link member  51  and is driven from the forward extending, rotating output shaft  52  of the motor  36 . The shaft  52  extends coaxially forward through the front boss  43  ( FIG. 12 ) of the motor  36 . 
   The transmission  50  ( FIGS. 5 and 12 ) includes a pinion gear  53  fixed on the motor shaft  52  for rotation thereby, and a face gear  54  which, as seen in  FIG. 12 , underlies the pinion gear  53 . The face gear  54  has a relatively large diameter central disk  56  carrying upward facing teeth  55  engaging corresponding teeth on the pinion gear  53  for rotation thereby. The face gear  54  includes a secondary pinion gear  57  fixed coaxially beneath the disk  56 , and of substantially lesser diameter, which in turn drives a relatively large diameter output gear  60 . 
   It will be understood that the pinion gear  53 , face gear  54 , secondary pinion  57  and output gear  60  are all provided with a full circumferential (360°) set of teeth, so that continuous rotation of the motor shaft  52  results in continuous rotation of the output gear  60 . For convenience in drawing, some or all the gear teeth are not shown in various of the drawings, the toothed meshing connection of the gears therein thus being only schematically shown. See for example  FIGS. 4 ,  10 ,  12 ,  13  and  14 . 
   An output shaft  61  is fixed to and coaxially upstanding from the output gear  60  ( FIG. 12 ) and fixedly rotatably drives an eccentric member  62  ( FIGS. 5 ,  10  and  12 ) spaced above the output gear  60 . In this embodiment, the output shaft is of rectangular cross-section to maximize its torque transmitting capability. 
   The eccentric member  62  comprises a radially extending disk  63  ( FIG. 5 ) coaxial with the output shaft  61  and fixedly surmounted by an eccentric circular cylinder  64  eccentrically rotatable with the output shaft  61 . 
   The link member  51  is generally T-shaped, as seen in  FIG. 13 , having a plate-like body  70  overlying the disk  63  of the eccentric member  62  and lying at right angles to the output shaft  61 , and further having a plate-like fork  71  fixed at the rightward ( FIGS. 5 ,  10 ,  12  and  13 ) end of the plate-like body  70  and extending in a plane substantially parallel to the output shaft  61 . The plane of the plate-like fork  71  is perpendicular to the intended direction of reciprocating movement of the link member  51 . The body  70 , at its end portion remote from the fork  71 , has an oblong through opening  72  snugly radially receiving the rotating eccentric cylinder  64  of the eccentric member  62 , as seen in  FIG. 10 . More particularly, the length direction of the oblong opening  72  extends parallel to the plane of the fork  71  and is of sufficient length to accommodate 360° rotation of the eccentric cylinder  64  without movement of the body  70  parallel to the plane of the fork  71 . On the other hand, the width of the oblong opening  72 , namely in a direction perpendicular to the plane of the fork  71 , corresponds substantially to the diameter of the eccentric cylinder  64 , providing a sliding clearance between the body  70  and eccentric cylinder  64 , so that rotation of the eccentric cylinder  64  will result in reciprocation of the link member  51  in a direction perpendicular to the plane of the fork  71 . 
   The plate-like body  70  includes a thickened rim  73  ( FIG. 5 ) around the oblong opening  72  and may thus be said to form a yoke for coaction with the eccentric cylinder  64 . The side edges of the body  70  are preferably also thickened to form parallel longitudinal guide rails  74  ( FIG. 10 ). 
   The above discussed moving elements of the transmission  50  are located and movably supported within the shell  26  as follows. The face gear  54  has coaxial downward and upward ( FIGS. 5–7 ,  10  and  12 ) extending stub shafts  75  and  76  respectively rotatably supported in coaxial bearing bosses  80  and  81  respectively fixed on the opposing faces of the shell parts  31  and  30  ( FIGS. 6 ,  7  and  12 ). Similarly, the output gear  60  and the eccentric member  62  have respective downward and upward extending stub shafts  82  and  83  coaxial with the output shaft  61  and rotatably supported in respective cylindrical bearing bosses  84  and  85  in the respective shells  31  and  30  ( FIGS. 5–7  and  12 ). The link member  51  is slidably guided for reciprocation in a notch  90  ( FIGS. 5 and 7 ) in the peripheral wall  91  of the left (upper in  FIG. 5 ) shell part  30 . The notch  90  has parallel opposed guide faces  92  ( FIG. 7 ) spaced apart to snugly slidably guide therebetween the opposite guide rails  74  of the link member  51 , and thus spaced at substantially at the maximum width of the link member. The thickness of the link member is guided for reciprocation between the peripheral edge  93  of the right (lower in  FIG. 5 ) shell  31  and the width wall  94  ( FIGS. 5 and 7 ) of the other shell part  30 . 
   The central length axis LA ( FIG. 10 ) of the link member intersects the central length axis MA of the motor shaft  52  at the axis SA of the output shaft  61  and stub shaft  83  ( FIGS. 10 and 12 ), at an angle equal to the angle between the central length axis of the handle  12  and barrel  13  of the housing  11 . Moreover, the length axes of the handle and barrel also intersect at the axis SA of the output shaft  61  when the drive unit  25  is installed in the handpiece housing  11  as hereafter discussed. In effect then, the link member longitudinal axis LA and motor shaft axis MA define the length axis of the barrel  13  and handle  12 , respectively, when the drive unit  25  is installed in the handpiece housing  11 . 
   The drive unit  25  is located within the handle  12 , as follows. As seen in  FIGS. 3 and 4 , transverse ribs  95  are molded into the interior surface of the handle  12  at opposing locations in the left and right housing parts  14  and  15  ( FIGS. 2–4 ). For drawing convenience, only the ribs in the right housing part  15  are shown, the ribs in the left housing part  14  being compatible. The ribs  95  locate the drive unit  25  in the rightward/leftward direction in  FIG. 2 . Further, the drive unit shell bosses  84  and  85  ( FIG. 5 ) protrude sideways from the drive unit shell and are pivotally received in corresponding hollow cylindrical bosses, one of which is shown at  96  in  FIG. 2 , and which extend toward each other from the interior of the left and right housing parts  14  and  15 . The hollow cylindrical boss  96  of the left housing part  14  is not shown but is opposed to and compatible with the housing part  96  shown in the right housing part  15  of  FIG. 2 . The drive unit  25  is thus, except for the lateral positioning defined by the ribs  95 , pivotally located within the handpiece housing  11  and is thus capable of some pivotal floating in the housing to achieve proper alignment of the longitudinal movement axis LA ( FIG. 7 ) of the link member  51  with respect to the barrel  13  and a pump unit  100  ( FIGS. 2–4  and  16 – 18 ) located in the barrel  13  as hereafter discussed. 
   Pump Unit 
   Turning now to the pump unit  100 , attention is directed to  FIGS. 2–4  and a 6   18 . The pump units includes a bellows  101  including an axially expandable and contractable, reciprocating, bellows wall  114  ( FIG. 18 ) and a forwardly extending, rigid annular flange wall  102 . Such flange wall  102  is loosely telescoped over a rigid, rearwardly extending annular flange  103  of a rigid, forwardly extending coaxial bellows housing  104 . 
   The bellows  101  and bellows housing  104  are preferably of molded plastics material. A resilient O-ring  105  ( FIGS. 16 and 19 ) is snugly radially disposed between the radially opposed, axially extending annular flanges  102  and  103 , to create a fluid seal therebetween and hence between the bellows  101  and bellows housing  104 , to prevent fluid leakage therebetween. The bellows  101  and bellows housing  104  have respective axially spaced radially extending steps  106  and  107  joined to the respective annular flanges  102  and  103  and axially spaced apart at a distance substantially greater than the diameter of the O-ring  105 , as seen in  FIG. 19 . The axial extending flanges  102  and  103  and radially extending steps  105  and  106  define an annular chamber  110  in which the O-ring  105  is axially loosely, and radially snugly and sealingly, disposed. Note that the radially opposed surfaces of the axially extending annular flanges  102  and  103  are cylindrical, such that neither has an annular groove in which the O-ring seats. Thus, the O-ring is free to roll on the radially opposed cylindrical surfaces of the axially extending flanges  102  and  103  and the O-ring  105  does not significantly interfere with axial separation of the bellows  101  and bellows housing  104  from each other. 
   Instead, such axial separation is prevented, as hereinafter further discussed, by a forwardly-rearwardly (leftwardly-rightwardly in  FIG. 2 ) spaced pair of ribs  111  ( FIG. 2 ) extending radially inward from the interior wall of the right housing part  15  and a corresponding, laterally opposed pair of mirror imaged ribs (not shown) extending laterally inward from the interior wall of the left housing part  14 . Such ribs  111  are also schematically indicated in  FIG. 18 . 
   The rear (right in  FIG. 19 ) end of the bellows housing axial flange  103  abuts the radially extending step  106  of the bellows  101  and the forward (leftward in  FIG. 19 ) end of the bellows axial flange  102  axially abuts a radial flange  112  which extends radially outward from and forwardly from the bellows housing step  107 . The forward end of the bellows axial flange  102  thus radially overlaps the bellows housing step  107  in snug but axially slidable relation thereto. A small forwardly extending annular rib  113  protrudes forwardly from the bellows radial step  106  toward the O-ring  105  to prevent rearward escape of the O-ring  105  from the space between the axially extending flanges  102  and  103 , in the event of slight axial shifting of the bellows  101  and bellows housing  104  away from each other. 
   The above mentioned radially inward extending ribs  111  of the handpiece housing  11  snugly axially oppose and sandwich therebetween the bellows radial step  106  and bellows housing radial flange  112  to positively prevent axial separation of the bellows  101  from the bellows housing  104 , when the pump unit  100  is installed in the housing  11 . 
   The above-mentioned bellows wall  114  extends rearward from the inner periphery of the radially extending annular step  106  of the bellows  101  ( FIG. 18 ) and consists of an axially collapsible and extensible, flexible, wave cross-section, peripheral wall  114 . The bellows wall  114  surrounds an axially expansible and contractible pumping chamber  115 . At the rear end of the bellows  101 , a radially extending drive end wall  116  closes the rear end of the bellows wall  114  and pumping chamber  115 . A stub  120 , having a radially enlarged head  121 , is fixed to and extends coaxially rearwardly from the drive end wall  116 . 
   To axially reciprocatingly drive (repetitively axially contract and expand) the bellows  101 , the above discussed link member  51  ( FIG. 5 ) of the drive unit  25  has its fork  71  provided with a central, radially opening, generally U-shaped slot  122  ( FIGS. 11–13 ). The slot  122  divides the fork  71  into a pair of tines  123  ( FIG. 11 ). The slot  122  opens leftwardly in  FIG. 2 , namely away from the rightward housing part  15  and toward the leftward housing part  14 . Thus, with the drive unit  25  located in the right housing part  12  as seen in  FIG. 3 , the pump unit  100  can be inserted into the rightward housing part  15 , with the stub  120  ( FIG. 18 ) inserted in the slot  122  of the fork  71  ( FIG. 11 ) so as to trap the tines  123  axially between the drive end wall  116  and head  121  of the bellows  101 , as generally indicated in  FIGS. 3 and 4 . To prevent the bellows stub  120  from accidentally radially escaping out the open end of the slot  122  in the fork  71 , the central portion  124  ( FIG. 11 ) of the slot  122  is undercut by inward tapering of an intermediate portion  125  of the slot  122  as seen in  FIG. 11 . The tapered portion  125  of the slot  122  ( FIG. 11 ) defines a snap fit detente for resiliently trapping the bellows stub  120  in the drive unit slot  122 . Thus, to install the bellows stub  120  in the slot  122 , the bellows stub  120  must be resiliently forced through the tapered portion  125  of the slot  122  and upon passing the latter, the stub resiliently snaps into the central portion  124  of the slot. The inner ends of the tapered portion  125  of the slot resiliently maintain the stub radially inboard thereof, in the central portion  124  of the slot  122 . 
   The stub  120  and hence the bellows  101 , and indeed the entire pump unit  100 , is thus freely rotatable about its length axis with respect to the fork  71 , so that the circumferential orientation of the drive unit  25  and the pump unit  100  is determined by the location thereof in the housing. The drive unit  25  and pump unit  100  are thus, to an extent, free to circumferentially float with respect to each other, about the connection of the stub  120  and fork  71 , without interfering with the circumferential location of the drive unit  25  and pump unit  100  in the housing  11 . Further, the edges of the slot  122 , in particular of the central portion  124  thereof, are rounded in cross-section, as is the stub  120 , to permit a modest amount of angular adjustment between the length axes MA and LA of the drive unit  25  and pump unit  100  and to allow the drive unit  25  and pump unit  100  to easily settle into their proper operating positions in the housing  11 . 
   A cylindrical plug  126  is coaxially fixed to the interior side (left side in  FIG. 18 ) of the bellows drive end wall  116  by a coaxial, rearward extending, undercut pin  127  snap fitted in a forwardly (leftwardly in  FIG. 18 ) opening recess in the stub  120 . The plug  126  has a diametral slot  130  opening forward from its front end and which faces forward toward a resilient valve member  131  ( FIGS. 16 and 18 ) to maintain liquid communication between the central and radially outer portions of the pumping chamber  115 . 
   The bellows  101  is thus a single element which carries out four different functions, namely sealing at the forward end, changing the pump chamber size in the middle thereof, the rearend acts as a piston and as a drive point. In addition, the front annular flange  102  helps locate the pump unit with respect to the housing barrel. 
   The pump unit  100  further includes a valve member  131 , which is a one piece member of suitable resilient material and which by itself constitutes the entire moveable inlet and outlet valve system for the pump unit  100 . More particularly, the valve member  131  comprises a short tubular central portion  132  ( FIG. 18 ) which coaxially connects a forward (leftward in  FIG. 18 ) tapering, duck bill type, outlet valve  133  and a rearwardly and radially outwardly extending umbrella type, inlet valve  134 . The umbrella valve  134  is annular and has a central opening  135  which communicates coaxially from the pumping chamber  115  in the bellows  101  forwardly through the tubular central portion  132  and outlet duck bill valve  133  of the valve member  131 . 
   The bellows housing  104  comprises a rear (right in  FIGS. 18 and 18C ) facing recess having a perimeter defined by the annular flange  103  of the bellows housing  104  and a rear facing radial wall  136  which defines the front end of the pumping chamber  115 . The umbrella valve  134  lies coaxially in the resulting recess  103 ,  136 . The forward facing perimeter  137  of the umbrella valve  134 , in its closed condition shown in  FIGS. 18 and 18C , presses forward against the radial wall  136  to seal thereagainst. The valve member  131  is held against the right (rearward) movement away from the bellows housing wall  136  by axial interference between a rightward facing, radially outward extending, annular step  140  ( FIG. 18C ) at the rear (right) end of the duck bill valve  133 , and a radially inward extending, leftward facing, annular flange  141  of the bellows housing  104 . The radially inward directed, annular flange  141  is axially interposed between, and forms a port  142  between, the rear facing recess  103 ,  136  and a coaxial, forwardly extending, cylindrical, irrigation liquid outlet, discharge, conduit  143  ( FIGS. 18 and 18C ). The tubular central portion  132  of the valve member  131  extends snugly axially through the port  142 . 
   To install the valve member  131  in the bellows housing  104 , the tapered outlet duck bill valve  133  is pushed forward through the port  142 , the bellows valve step  140  snaps forwardly (leftwardly in  FIG. 18C ) past the bellows housing flange  141 , and the sealing perimeter  137  of the umbrella valve  134  is thereby pulled forwardly resiliently against the rearward facing bellows housing wall  136 , leaving the valve member  131  with its duck bill valve  133  and umbrella valve  134  both in their closed condition shown in  FIGS. 18 and 18C . 
   The bellows housing  104  further includes an annular liquid jacket  144  ( FIGS. 18 and 18C ) surrounding the rear portion of the liquid outlet conduit  143  and defining radially therebetween an annular liquid inlet chamber  145  ( FIGS. 18 ,  18 C and  19 ). The inlet chamber  145  communicates between a radial inlet port  146  ( FIGS. 16 and 19 ), which opens radially outward through the side of the bellows housing  104 , and an annular space  147  ( FIG. 18C ). The annular space  147  is bounded by the forward face  150  and tubular central portion  132  and sealing perimeter  137  of the umbrella valve  134  and the radial face  136  of the recess  103 ,  136  of the bellows housing  104 . 
   Thus, a rightward pullback of the bellows head  121  axially expands the bellows, from its  FIG. 18A  position towards its  FIG. 18  position. This reduces the pressure within the bellows. This in turn keeps the duck bill valve  133  closed and pulls the sealing perimeter  137  of the umbrella valve  134  rightwardly away from the bellows housing recess radial wall  136  and draws liquid from the port  146  through the annular inlet chamber  145 , around the perimeter  137  of the open umbrella valve and into the interior of bellows. 
   On the other hand, a leftward push forward of the bellows head  121  axially compresses the bellows from its  FIG. 18  position toward its  FIG. 18B  position and raises the pressure in the bellows, to close the umbrella valve  134  and open the duck bill valve  133  and force a pulse of liquid out of the bellows forwardly through the duck bill valve  133  and liquid outlet conduit  143 . 
   Irrigation liquid is drawn to the inlet port  146  of the bellows housing  104  through an elbow  151  ( FIG. 19 ). The outlet end  152  of the elbow and the inlet port  146  are cylindrical, with the elbow outlet end  152  being a snug axially sliding fit in the inlet port  146 . An axially elongate, annular groove  153  in the outer periphery of the elbow outlet  152  houses a seal ring, here an O-ring,  154  which bears sealing and rollingly on the radially opposed and surrounding surface of the inlet port  146  to prevent liquid leakage out of the elbow  151  at its interface with the inlet port  146 . The elbow  151  is not mechanically interlocked with the inlet port  146  but can slide in and out with respect thereto. The elbow  151  is held in place with its outlet end  152  sealingly within the port  146  by bearing of a portion  155  ( FIG. 4 ) of the handpiece housing barrel  13  against the outboard surface  156  of the elbow  151 , with the pump unit installed in the handpiece housing  11 . The elbow  151  here fixedly carries a pair of parallel fins  157  ( FIGS. 16 ,  17  and  19 ). The fins  157  extend radially from the rear inlet end portion of the elbow  151  and axially sandwich therebetween the flanges  106  and  112  of the bellows  101  and bellows housing  104 , at least to help the housing ribs  111  ( FIG. 18 ) fins  157  prevent axial separation of the bellows and bellows housing. The housing ribs  111  and fins  157  are more or less evenly circumferentially located around the bellows  101  and bellows housing  104 . 
   An elongate flexible irrigation liquid supply hose  160  ( FIGS. 2 ,  4 ,  16 ,  17 ,  19 ,  22 ,  23 ,  25  and  29 ) has a forward end  161  which telescopes sealing and fixedly over the rear end  162  of the elbow  151  as seen in  FIGS. 19 and 29 . Although an annular barb is shown at  162  (for example in  FIG. 19 ) a barbless, cylindrical end  162  is satisfactory. In the assembled handpiece, the irrigation liquid hose  160  extends rearward from the elbow  151  ( FIG. 4 ) in the barrel  13  of the housing and angles downwardly and rearwardly along the bottom of the handpiece handle  12  to exit rearwardly and downwardly through a hole  163  ( FIG. 2 ) in the bottom end wall  164  of the handpiece housing  11 . A clamp plate  165  (FIGS.  2 ,  3  and  4 ) of bent cross-section has a perimeter groove  166  for receiving the edges of the hole  163  in the housing bottom end wall  164 , such that the clamp plate  165  is trapped in and partly closes the hole  163  in the bottom end  164  of the housing handle  12  when the housing is fully assembled. A notch  167  ( FIG. 2 ) in the rightward end of the clamp plate  165  permits exit therethrough of irrigation liquid supply hose  160  from the handpiece housing  11  and snugly and frictionally grips such hose, without crushing or collapsing it, so that such hose  160  cannot easily be pulled out of the housing  11  or off the elbow  151 . 
   The irrigation liquid hose  160 , the inlet line, integrally therewith, a smaller diameter rib  170  ( FIGS. 2 ,  16 , and  17 ) A plurality (here three) insulated electrical conductors (wires)  171  have intermediate portions contained within and extending the length of the rib  170 . Forward end portions of the insulated wires  171  emerge from the forward end of the rib  170  and carry conventional electrically conductive connectors  175 . The forward end of rib extend through the notch  167  ( FIG. 2 ) and ends just inside the bottom portion of the handle of the housing  11 , as seen in  FIG. 4 . The forward ends of the conductors, carrying the connectors  175 , extend into the lower portion of the handpiece handle  12 . Thus, as apparent from the below description, rib  170  functions as a cable through which conductors  171  extend from the battery pack to the handpiece housing  11 . 
   The insulated electrical conductors  171  extend along the length of the central portion of the liquid supply hose  160  and have rear ends provided with respective electrically conductive connectors  176  ( FIGS. 22 and 29 ), such that electric current can flow from a given rear connector  176  through its corresponding insulated electrical conductor  171  and to its corresponding front electrically conductive connector  175  in a conventional manner. Short rear portions of the conductors  171  are loose and moveable with respect to the liquid supply hose  160  as seen in  FIGS. 22 and 29 . 
   The electrical connectors  175  and  176  are conventional crimp type connectors. 
   Instead of being molded in or otherwise constrained within the generally circular cross section rib  170  in  FIG. 2 , the elongate central portion of the insulated electrical conductors  171  may be fixed side by side, in a flat array, to the outside of the liquid hose  160 , as shown in  FIGS. 22 and 29 , and such can be accomplished by adhesive bonding or by any other convenient means. 
   The hose  160 ,  170  thus serves the dual use of conveying both irrigation liquid and electric operating power. 
   The length of the central portion of the liquid hose  160 , to which the insulated conductors  170  are fixed, preferably extends several feet (for example 8 to 10 feet) from the handpiece  10 . The rear end  177  ( FIGS. 22 and 23 ) of the liquid hose is here provided with a fitting  180  of hollow tubular construction open to axial liquid flow therethrough. The fitting  180  comprises a forward end portion  181  ( FIG. 23 ) fixed sealingly telescoped in the rear end  177  of the liquid hose  160 , a square central flange  182  ( FIG. 22 ) and a rear end portion (or “spike”)  183  having a sharpened tip  184 . The tip  184  is capable of conventional insertion into a conventional source S ( FIG. 22 ) of irrigation liquid, for example a conventional supply bag, for conveying irrigation liquid therefrom forward into the hose  160 . The square flange  182  prevents rotation of the fitting  180  in the casing  191 , which helps when removing the spike  183  from the liquid supply bag. In the embodiment shown, the rear end portion  183  is covered by a protective cap  185  prior to use so that the sharpened tip  184  will not accidentally be dulled. 
   Thus, the length of the liquid supply hose  160  allows the irrigation liquid source S to be located at a distance from the handpiece and thus out of the way of the surgical personnel at the operating table where the handpiece  10  is to be used. 
   Electrical Power Supply Unit 
   To provide operating electrical power to the motor  36 , a compact, self contained electrical supply unit  190 , a battery pack, ( FIGS. 20–25  is fixed on the rear portion of the liquid hose  16 O. The power supply unit is thus located remotely from the handpiece  10 , adjacent to the source S of irrigation liquid. 
   The power supply unit  190  comprises a casing  191  preferably of rigid molded plastics material. The casing  191  here comprises a relatively deep, substantially rectangular pan  192  ( FIG. 2 ) whose top (as oriented in  FIGS. 22 and 23 ) is fixedly closed by a cover  193 . The pan  192  has front and rear end walls  194  and  195  ( FIGS. 23 ,  23 A and  24 ) having fixed upward opening slots  200  each defined by a laterally spaced, opposed pair of U-shaped flanges  201  ( FIGS. 23A and 23B ). The slots  200  are undercut in that each has a mouth  202  laterally narrower than the remainder of the slot  200  and communicating between the remainder of the slot  200  and the interior cavity of the pan  192 . The undercut slots  200  are of constant cross-sectional size and shape vertically (i.e. into and out of the page in  FIG. 24  and up and down in  FIG. 23 ). 
   For convenient reference in the drawings, the reference numerals  200  and  201  are suffixed, so that the undercut slots and U-shaped flanges on the front pan wall  194  are indicated by the reference characters  200 F and  201 F and the undercut slots and U-shaped flanges on the rear pan wall  195  are indicated at 200R and 201R. 
   The U-shaped flanges  201 F defining the slots  200 F on the forward end wall  194  start substantially from the pan bottom wall  196  and extend a bit less than half way up the front end wall  194 . 
   On the other hand, the U-shaped flanges  201 R of the slots  200 R on the rearward end wall  195  of the pan are spaced above the bottom wall  196  of the pan upon respective block-like pillars  203  which define an up-facing bottom  204  for each of the U-shaped flanges  201 R on the rear pan wall  195 . 
   Rising from bottom wall  196  of the pan between the two central pillars  203  to a height below the bottoms  204  of the slots  200 R thereof, is a central block  205  from which forwardly extends, along the pan bottom wall  196 , a T-shaped flange  206  ( FIG. 23B ) of constant cross section vertically and defining a pair of vertically open and laterally oppositely opening grooves  207  disposed immediately forward from the two central pillars  203  on the rear pan wall  195 . 
   Two such undercut slots  200 F are spaced symmetrically side by side on the front pan wall  194 . Similarly, and at the same effective lateral spacing, two such slots  200 R are spaced laterally side by side on the pan rear wall  195 . 
   Springy, electrically conductive sheet metal battery contacts of three different kinds are indicated at  210  and  211  and  212  and  FIGS. 26 ,  27  and  28  respectively. 
   A pair of such contacts  210  are provided and each comprises a generally rectangular foot  213  adapted to snugly slide down into a respective undercut slot  200 F at the pan front wall  194 . Each foot  213  is provided with resilient toes  214  angled out of the plane of the foot  213  and adapted to bite against the interior of the corresponding undercut slot  200 F to fix the corresponding battery contact  210  in place therein. 
   Similarly, each of a pair of battery contacts  212  ( FIG. 28 ) has a resilient fork-shaped foot  215  adapted to fit snugly and slidingly down into the corresponding undercut groove  200 R at the rear wall  195  of the pan  192  and with springy toes  216  for fixedly gripping the interior of the corresponding undercut slot  200 R. 
   In a generally similar manner the single, low speed battery contact  211  ( FIG. 27 ) has a resilient U-shaped foot  217  for sliding down over the T-shaped flange  206  ( FIG. 23B ), with springy toes  218  bent out of the plane of the foot  217  for bitingly engaging the walls of the grooves  207  of the T-shaped flange  206 . 
   Each of the battery contacts  210 ,  211  and  212  thus slides with its corresponding foot into the desired location with respect to the grooves  200 F,  200 R and  207  and locks fixedly therein. This is generally indicated in  FIGS. 22–24 . The battery contacts  210 ,  211  and  212  have respective resilient fingers  221 ,  222  and  223  ( FIGS. 26 ,  27  and  28  respectively), two each for the battery contacts  210  and  211  and one each for the battery contacts  212 . Such fingers  221 ,  222  and  223  protrude from the respective slots  200 F,  200 R and  207  into the interior of the pan  192  for electrically contacting batteries  230  ( FIG. 22 ) to be housed in the pan  192 . Further, the battery contact  211  and each of the battery contacts  212  ( FIGS. 27 and 28  respectively) have an upstanding terminal ( 224  and  225  respectively) of simple rectangular shape for releasable telescoped engagement within a respective one of the connectors  176  at the rear ends of the three insulated electrical conductors  171  ( FIG. 22 ). 
   Turning now to the arrangement of the batteries  230  within the pan  192 , one embodiment according to the invention advantageously uses batteries of a kind widely available in retail stores, namely AA size alkaline batteries. In addition to their wide availability to the public, these batteries advantageously are inexpensive, have a long shelf life and provide full operating voltage until almost fully discharged. In the embodiment shown, eight such batteries  230  are provided and are individually indicated at B 1 , B 2 , B 3 , B 4 , B 5 , B 6 , B 7  and B 8 . As shown in  FIGS. 22–24 , ribs  231  extending circumferentially within the pan  192  cradle the batteries  230  fixedly but removably within the pan  192 . The polarity of the eight batteries is indicated by “plus” signs marked thereon. As seen in the drawings, the batteries  230  are arranged in four rows of two head-to-tail batteries each. Four of the batteries  230  lie in the bottom ( FIGS. 22 and 23 ) of the pan in two rows of two each and the remaining four batteries  230  lie on top of those. 
   The ends of the battery rows bear variously on the above discussed battery contacts  210 ,  211  and  212  as generally indicated for example in  FIG. 22  and also in the schematic circuit drawing in  FIG. 22A . More particularly, the four batteries B 1 , B 2 , B 3  and B 4  defining a vertical plane nearest to the viewer in  FIG. 23  are connected in series from the near connector  212  leftwardly through the top row of batteries, down through the near upstanding connector  210  and thence rightwardly through the bottom pair of batteries to the lower rear connector  211 . The remaining four batteries B 5 –B 8  are arranged in a vertical plane behind above-mentioned batteries B 1 –B 4 . More particularly, the batteries B 5 –B 8  connect in series from the far side of the lower rear connector  211  forwardly (leftwardly in  FIG. 22 ) to the far connector  210 , upwardly therethrough, and then rearwardly back to the far upper connector  212 . 
   The cover  193  ( FIGS. 23 and 25 ) has plural, laterally extending, depending ribs  232  ( FIGS. 23 and 25 ) intended to seat upon the uppermost batteries B 1 , B 2 , B 7  and B 8  and fix the batteries B 1 –B 8  in the pan with the cover  193  fixed in its normal closed position atop the pan  192 . The cover is fixedly securable atop the pan by any convenient means, such as snap fit connectors, a portion of which are generally shown in  233  in  FIG. 22 , and generally like those discussed above with respect to the handpiece housing  11 , as at  16 , and as generally discussed with respect to the drive unit shell  26 , as at  32 ,  33 . 
   The aforementioned rear end  177  of the hose  160  extends through the casing  191  along the horizontal parting plane between the pan  192  and cover  193 , and so lies close adjacent the topmost batteries B 1 , B 2 , B 7  and B 8 . 
   Hollow front and rear bosses  234  and  235  ( FIGS. 23 and 25 ) extend forward and rearward respectively, from the casing  191 . At the parting plane between the pan  192  and cover  193 , the bosses  234  and  235  are notched (for example at  236  in  FIG. 22 ) for extension therethrough of the rear end  177  of the liquid hose  160 . The rear hollow boss  235  is sized and shaped to receive radially therein the square flange  182  ( FIG. 23 ) on the rear end of the liquid hose  160 , and thereby axially fix the rear end of the liquid supply hose  160  within the casing  191  and nonrotatably fix the fitting  180  to the battery casing  191 . The notch  236  in the front boss portion  234  on the cover  193  is indented by one or more small recesses  237  for receiving axially therethrough the rib  170  containing the insulated electrical conductors  171 , whose rear end connectors  176  are respectively fixed to the terminals  224  and  225  of the battery contacts  211  and  212 . 
   Trigger Unit 
   The handpiece  10  further includes a trigger unit  240  ( FIGS. 2–4 ) for controlling actuation of the motor  36  and, by extension, pump unit  100 . The trigger unit  240  comprises a generally L-shaped trigger member  241  ( FIGS. 2 ,  4  and  4 A), that functions as a control switch, and that comprises an elongate trigger lever  242 . The upper, forward (leftward in  FIGS. 2 and 4 ) end of the trigger lever is pivoted by laterally extending integral pins  243  pivotally receivable in suitable holes in laterally opposed bosses (one of which is shown in  FIG. 2 ) in the opposed lower edges of the housing parts  14  and  15 , near the rear end of the barrel  13 . Snapping together of the two housing parts  14  and  15  thus captures the pivot pins  243  and pivotally mounts the trigger with respect to the handpiece housing. 
   The trigger lever  242  includes a transverse ridge  245  ( FIG. 4 ) near to but spaced rearwardly from the pivot pins  243  and facing the underside of the barrel  13  and adapted to bear on the underside thereof in the manner of a fulcrum. By far the major length  246  of the trigger lever  242  is to the rear (right in  FIG. 4 ) of the fulcrum ridge  245 . This rearward trigger part  246  is relatively rigid in the portion thereof spaced at least somewhat to the rear of the fulcrum ridge  245 . Such rigidity is assisted by a forward facing longitudinal reinforcement rib  247  extending rearward along the front face of the trigger lever  242  from a point near the fulcrum ridge  245 . The front of the trigger lever  242 , to the rear of the fulcrum ridge  245  is, in the embodiment shown, provided with transversely extending ribs  248  to provide the user with a non-slip grip of the trigger lever  242 . 
   The trigger lever  242  is bendable near the fulcrum ridge  245 , both to the front and rear thereof, in a resilient manner. In this way, the resilience of the trigger lever tends to hold it in its forward, inactive position shown in  FIG. 4 , with the fulcrum ridge  245  bearing on the underside of the handpiece barrel  13 . On the other hand, when the user grips the handle  12  and squeezes the trigger lever  245  toward it, in the direction indicated by the arrow TA in  FIG. 4 , the trigger lever bends in the region of the fulcrum ridge  245 , tending to straighten from its relaxed convexly forwardly curved configuration of  FIG. 4 , so that the rear face of the trigger lever can be pulled into the dotted line position  242 P, substantially against the front face of the handle  12 . Upon release of the trigger by the user, the natural resilience of the trigger lever  242  unbends it back to its solid line forward position shown in  FIG. 4 . Accordingly, the trigger naturally returns forward to its non-operative position without need for a separate return spring. 
   The trigger arm  251  fixedly carries a thumb  250  ( FIG. 4A ) intermediate it ends in the housing handle  15  and which interferes with the housing wall adjacent the hole  252 , to prevent the resilient restoring force of the trigger lever  242  from pulling the trigger arm  251  leftwardly ( FIG. 4A ) out of the housing handle  12 . 
   A plank-like switch contact support arm  251  ( FIGS. 2 ,  4  and  4 A) protrudes substantially at a right angle from the rear, or bottom, end of the trigger lever  242  and extends upwardly and rearwardly (in  FIG. 4 ) into the lower portion of the handle  12 , loosely through a hole  252  ( FIG. 4A ) in the opposing bottom wall of the handle. A plate-like electrically conductive contact blade  253  fixedly extends through the thickness of the arm  251 , and has a front portion exposed towards said motor and a rear portion exposed toward the bottom end  164  of the handpiece handle. 
   A pair of rectangular posts  255  and  256  protrude fixedly into the interior of the handle  12  from the inside of the right housing part  15 , about midway between the drive unit  25  and the housing bottom end  164  ( FIGS. 4A and 4B ). Each post  255  and  256  includes a T-shaped flange  260  extending substantially forward toward the drive unit  25 . Each T-shaped flange  260  defines a pair of oppositely facing grooves  261  ( FIG. 4C ). 
   Electrically conductive, spring-like metal contacts  262  and  263  ( FIGS. 4A and 4C ) each have a substantially U-shaped foot  264  for reception on the T-shaped flange  260  of the corresponding posts  255  and  256 . The contacts  262  and  263  further each have a substantially rectangular, projecting terminal  265  for telescopic fixing thereon, in electrically connected relation, a corresponding one of the front connectors  175  of the three insulated electrical conductors  171 . The electrical contacts  262  and  263  further have respective, generally L-shaped, plate-like, flexible contact leaves  266  and  267  ( FIG. 4C ). The contact leaves  266  and  267  extend toward the drive unit  25  as seen in  FIG. 4A . 
   Protruding rearwardly from the motor  36  are a pair of electrically conductive contacts  270  and  271  ( FIGS. 4A and 9 ). The contact  271  is a conventional terminal (like those at  224 ,  225  and  265 ) for receiving one of the front connectors  175  in fixed and electrically conductive relation thereon. 
   In contrast, the contact  270  is an elongate, springy rectangular piece, bent intermediate its ends in dogleg fashion, and angling from the rear end of the motor  36  rearwardly and somewhat rightwardly (in  FIG. 4A ) to a free end portion spaced near the contact leaves  266  and  267 . 
   Gradual pressing of the trigger lever  242  toward the handle housing (rightwardly in  FIGS. 4 and 4A ) moves the arm  251  and hence the contact blade  253  progressively further into the handle  12  through a series of positions, three of which are indicated in broken lines at  253 A,  253 B and  253 C in  FIG. 4A . 
   The free (rightward in  FIG. 4A ) end of the arm  251  is beveled at  272  to help it ride over the contacts  266  and  267  as the trigger lever  242  is sequentially squeezed more and more toward the handle  12 . The arm  251  is progressively resiliently bent, like a leaf-spring, as its free end rides over the fixed contacts  266  and  267 , to firmly press its contact blade  253  against the latter. 
   Thus, as the trigger lever  242  is pressed toward the handle  12 , the beveled free end of the arm  251  rides over the contact leaf  266  past its dotted line position  253 A and toward its dotted line position  253 B. As the free arm end approaches position  253 B, the contact blade  253  slides into electrical contact with the contact leaf  266  and the motor contact  270  to establish electrical connection therebetween. The motor contact  270  resiliently bends to allow continued travel of the contact blade  253  and arm  251  further into the handle, as indicated in dotted line at  270 B, and to press firmly against the contact blade  253 . Given only a light pull on the trigger lever  242 , the arm  251  and contact blade  253  tend to stop in the position indicated in dotted lines at  253 B, by reason of the free end of the arm  251  colliding with the contact leaf  267 . In this “B” position, electric current is fed to the motor  36  only from half the battery collection, namely batteries B 1 , B 2 , B 3  and B 4  in  FIG. 22A . The motor  36  thus runs at only a preselected fraction of its full speed and the pump unit  100  outputs irrigation liquid pulses at a desired frequency and amplitude, which are less than the maximum available. The apparatus is thus operated in its low output mode. The colliding of the free end of the trigger arm  251  with the contact leaf  267  gives tactile feedback to the user, that the low output mode of the handpiece has been selected. 
   Further pulling in of the trigger lever  242  by the user causes the beveled free end of the arm  251  to bend rightwardly ( FIG. 4A ) the contact leaf  267  to a dotted line position indicated at  267 C, allowing the free end of the arm  251  to override the contact leaf  267 , such that the contact blade  253  moves into its “full-pull” dotted line position  253 C and further bends the motor contact  270  its dotted line position  270 C. In this final position, the contact blade  253  establishes electrical contact between the motor contact  270  and the contact leaf  267 , thereby applying the full series voltage of all eight of the batteries B 1 –B 8  to the motor  36  to operate the latter at its full speed and thereby drive the pump unit  100  at its full output, namely to provide irrigation liquid pulses out of the pump unit  100  at maximum pulse amplitude and frequency. 
   When the user releases the trigger lever  242 , the resiliently bent trigger lever  242 , due to its inherent resilience, springs back from its fully pulled-in position indicated in broken lines at  242 P, to its solid line rest position indicated at  242  ( FIG. 4A ). The electrical connection between the contact  262  or  263  and the contact  270  is broken. 
   Suction Hose 
   A flexible suction hose  280  ( FIGS. 2 and 3 ) is led along within the housing (within the lower part of the housing in  FIG. 3 ) past the drive unit  25  and pump unit  100 . The above-mentioned clamp plate  165  includes a tubular structure molded thereinto and defined by a forward nipple  282  in the handle  12  and, in coaxial fluid communicating relation therewith, a rearward nipple  283  which extends rearwardly out of the bottom end  164  of the handpiece handle  12 . The rear end portion  281  of the suction hose  280  is sealingly and fixedly telescoped over the front nipple  282 . A conventional flexible hose, not shown, is conventionally and sealing telescopable over the rear nipple  283  for connecting same to a conventional suction source, as schematically indicated at SS in  FIG. 3 . 
   The front end portion  284  of the suction nose  280  is sealingly telescoped over a rearward opening nipple  285  on a short suction conduit  286  ( FIGS. 2 ,  3 ,  16 ,  17  and  18 ). The suction conduit  286  ( FIG. 18 ) is fixed side by side, in piggyback fashion, on the periphery of the irrigation liquid conduit  143  and hence is a part of (preferably an integral plastic molded part of) the bellows housing  104 . 
   The clamp plate  165  serves several purposes. It provides a suction hose connection, bears on the irrigation liquid hose where it enters the handpiece housing, and helps align the rear (rightward in  FIG. 4 ) end wall portions of the housing halves as they are assembled together, and in so doing, is itself fixed on the housing. In addition, the clamp plate  165  is of one piece, preferably a plastic molding, and is partially recessed into the handpiece so that it does not make the handpiece look any bigger. 
   Tip Unit 
   A tip unit  291  ( FIGS. 8 ,  8 A and  8 B) is releasably fixable on the front end of the handpiece  10  and extends forward therefrom for applying irrigation liquid pulses and/or suction to a surgical site indicated schematically at SU in  FIGS. 8 and 8B . The tip unit  291  ( FIG. 8 ) comprises a coupling  292 , a front cover  293  fixed to the front of the coupling  292 , and an elongate hollow wand  294  extending forwardly from the coupling and front cover for aiming at a surgical site SU. The coupling  292 , cover  293  and wand  294  are preferably one piece molded plastic units. The wand  294  is preferably of clear plastics material. 
   The tip unit  291 , and more specifically the coupling  292 , is releasably fitted in fluid tight relation to the front of the bellows housing  104  of the pump unit  100  and is releasably latched within the open front end of the handpiece housing barrel  13  as hereinafter discussed. 
   More particularly, the coupling  292  ( FIG. 8 ) comprises a shallow, forward opening cup  295  having a flat base wall  296  from which forwardly extends a shallow peripheral wall  297 , thereby defining a forward opening recess  300 . Coaxial irrigation liquid nipples  301  and  302  extend fixing rearwardly and forwardly, respectively, from the base wall  296  and together define a coaxial bore  303  therethrough and through the base wall  296 . The rear nipple  301  is snugly but slidably receivable rearwardly into the open front portion of the liquid outlet conduit  143  of the bellows housing  104 . An O-ring  304  seats in an annular groove outward facing on the rear nipple  301  and sealingly engages the interior of the liquid outlet conduit  143  to prevent irrigation liquid leakage therebetween. 
   The wand  294  includes a coaxial, relatively small diameter, irrigation liquid outlet tube  305  which at its rear end is telescoped fixedly and sealingly within the bore  303  of the front and rear nipples  301  and  302  for receiving a pulsed flow of irrigation liquid from the irrigation liquid outlet conduit  143  of the bellows housing  104 . 
   The coupling  292  further includes a suction nipple  306  fixedly extending rearward from the base wall  296  in spaced parallel relation with the irrigation liquid nipple  301 . The suction nipple  306  is snugly insertable rearwardly coaxially into the front opening suction conduit  286  of the bellows housing  104 . An O-ring  310  is axially sandwiched between the rear end of the suction nipple  306  and a front facing annular step  311  at the rear end of the suction conduit  286  to prevent leakage therebetween. 
   The coupling  292  further includes a leaf spring-like, generally U-shaped latch arm  312  which extends rearward from the peripheral portion of the base wall  296 , curves radially outwardly and forwardly, and extends forward past the front cover  293 , in radially outwardly spaced relation from the wand  294 . A wedge-shaped, transverse ridge  313  on the exterior base of the latch arm  312  is approximately centered between the front and rear ends of the latch arm. A circumferentially extending, radially inward protruding rib  314  ( FIGS. 2 ,  3  and  8 ) on the interior face and at the open front end of the right housing part  15  (at the front end of the barrel  13 ) opposes the latch arm  312 , immediately ahead of the ridge  313 , with the tip unit  291  installed on the front end of the handpiece  10  as shown in  FIG. 8 . The ridge  313  has a front facing step which abuts interferingly with the housing rib  314  to releasably block removal of the tip unit from its installed condition shown in  FIG. 8 . To remove the tip unit from the front end of the handpiece, the user simply presses radially inward against the forward protruding end portion  315  of the springy latch arm  312 , sufficient to radially inward displace the ridge  313  out of interfering relation with the rib  314  and thereby unlatch the tip unit from the front end of the handpiece. This allows forward removing the tip unit  291  from the open front end of the handpiece barrel  13  and removing of the irrigation liquid and suction nipples  301  and  306  from the liquid outlet conduit  143  and suction conduit  286  of the bellows housing  104 . 
   The tip unit  291 , or any alternative tip unit having a substantially identical coupling and front cover, can be installed operatively on the front end of the handpiece  10  by inserting same into the open front end of the handpiece barrel  13  so that the nipples  301  and  306  enter the liquid and suction conduits  143  and  286  respectively, to their position shown in  FIG. 8 . During this installation, the forward facing slope of the wedge cross-section transverse ridge  313  slides rearwardly past the housing rib  314 , bending the springy latch arm  312  radially inward as generally indicated by the arrow L in  FIG. 8 , so that the wedge cross-section ridge  313  can snap rearwardly past the rib  314  at the open front end of the housing barrel  13 . Thus, the tip unit  314  can be slid axially into the front end of the barrel  13  and upon reaching its innermost position latches itself against unintended removal. In its installed condition of  FIG. 8 , the tip unit is substantially rigidly fixed with respect to the front end of the bellows housing  104  and hence with respect to the handpiece barrel  13 . 
   The front cover  293  ( FIG. 8 ) comprises a plate  320  which extends radially of the wand  294  and of the length axes of the barrel  13  and the pump unit  100 . The peripheral shape of the plate  320  conforms to the cross-sectional shape of the front end of the barrel  13 , so that the perimeter of the plate  320  is substantially flush with the outer periphery of the open front end of the barrel  13 , and so that the plate  320  effectively covers the open front end of the barrel  13 . The peripheral shape of the plate  320  and cross-sectional shape of the front end of the barrel  13  in one embodiment is generally D-shaped, with a generally flat underside and a convexly curved top and sides. The plate  320  is not intended to seal the open front end of the barrel  13  and so need not tightly abut same. Since the peripheral wall  297  of the cup  295  fits easily within the open front end of the barrel  13 , the plate  320  extends radially outwardly beyond the cup  295 , as seen in  FIGS. 8 ,  8 A and  8 B. 
   The front cover  293  includes an annular flange  322  extending axially rearwardly therefrom, radially snugly into the cup  295  of the coupling  292  to bottom rearwardly and sealingly against a resilient gasket  321  which is disposed against the front face of the base wall  296  of the cup  295 . Respective holes in the gasket  321  loosely surround the front nipple  302  and leave fully open the communication between the interior of the suction nipple  306  and the interior of the cup  295 . The front cover  293  further includes a further annular flange  323  extending fixedly and forwardly from the plate  320  in coaxial alignment with the through hole  324  in the plate  320 . 
   The rearward annular flange  322  of the front cover  293  is fixedly secured within the cup  295  of the coupling  292  by any convenient means, for example by snap fit connectors on the opposing faces of such flange  322  and the peripheral wall  297  of the cup  295 . For example, the cup peripheral wall  297  may be provided with several circumferentially spaced rectangular holes  325  ( FIGS. 8A and 8B ) for snap fit reception therein of small radially outward extending protrusions schematically indicated at  326  on the outside of the rearward annular flange  322 . 
   The wand  294  further includes a relatively large diameter elongate suction tube  330  ( FIGS. 8A and 8B ) which loosely coaxially surrounds the irrigation liquid outlet tube  305  ( FIG. 8 ) and extends substantially to the front end of the latter. The rear end portion  331  of the suction tube  330  is radially enlarged to provide a radially shallow, axially elongate flange protruding radially outward therefrom and which is axially trapped between the plate  320  and the gasket  321  backed by the base wall  296 . This serves to rigidly fix the suction tube  330  with respect to the coupling  292  and front cover  293 . A port  332  in the sidewall of the suction tube  330  near its rear end communicates with a loosely surrounding annular chamber  333  defined between the plate  320  and base wall  296  of the front cover  293  and coupling  292  respectively. 
   The front end of the irrigation liquid tube  305  is held coaxially fixed within the front end portion of the surrounding suction tube  330  by any convenient means, such as radial, circumferentially spaced, webs  334  ( FIG. 8 ). Accordingly, with a tip unit  291 , of the general type above described, installed on the front end of the handpiece, as shown in  FIG. 8 , irrigation liquid pulses from the pump  100  pass forwardly within the liquid tube  305  and are projected from the front (left in  FIG. 8 ) end thereof, as schematically indicated by the arrows PL. At the same time, liquid and particulate debris at the surgical site SU are drawn into the front (left in  FIG. 8 ) end of the suction tube  330 , pass rearwardly along the length thereof, through the port  332  into the chamber  333  and rearwardly through the nipple  306  and suction nipple  285 . 
   With the exception of a few components such as the motor  44 , the various electrically conductive contacts, the elongate insulated conductors, the various seal rings (for example  105 ,  154 ,  304  and  310 , the gasket  321 , as well as the suction and irrigation liquid hoses, the remaining major components, while possibly manufacturable of a variety of materials, are economically manufacturable of available molded plastics materials. For example, the valve member  131  may be of rubber or a synthetic substitute or similar resilient plastic. Similarly, the bellows  101  is preferably molded of a suitable resilient plastic material capable of the bellows expansion and contraction movements shown in the drawings. The trigger unit  240  and the latch arm  312 , while of substantially rigid plastics material, are elastically bendable to the extent required to suit the present description. Similarly, components to be snap-fitted together are substantially rigid but have sufficient resilience to permit the required described snap fitting. 
   The present invention can be constructed at relatively low cost and is thus practically manufacturable as a disposable tool, both the handpiece  10  itself and the accompanying electric power supply unit  190  being disposable after use with a single surgery patient. 
   OPERATION 
   The apparatus is quickly and easily assembled. The drive unit  25  ( FIG. 12 ) is assembled by, in effect, “dropping in” elements in proper sequence into the right (lower in  FIG. 12 ) shell  31  and covering same with the other shell  30 . More particularly, output gear  60 , face gear  54  and motor  36  (with attached pinion gear  53  and electric contacts  270  and  271 ) are “dropped” into their respective locations in the upturned shell part  31 , in that sequence. The rectangular shaft  61 , topped by the eccentric member  62 , drops into the corresponding hole in the output gear  60  and the link member  51  drops onto the eccentric member. The other shell part  30  is then snap fitted over the filled shell part  31 , completing the drive unit  25 . 
   The pump unit  100  is assembled by coaxially telescoping together its elements shown in  FIG. 18  and then plugging into the inlet port  146  ( FIG. 19 ) the elbow  151  with the O-ring  154  and hose  160  assembled thereon. 
   The stub  120  ( FIG. 18 ) of the drive unit  100  can then be snapped into the slot  122  of the drive unit fork  71  ( FIG. 2 ) to connect the drive unit  25  operatively to the pump unit  100 . The suction hose  280  can then be connected to the pump unit nipple  285  and to the nipple  282  on the clamp plate  165 . Thereafter, the two assemblies above described can be laid into the rightward ( FIG. 2 ) housing part  15  in the following order, namely liquid hose  160  ( FIG. 4 ), drive unit  25  and pump unit  100  ( FIG. 3 ) and, last, suction hose  280  and clamp plate  165 . 
   The trigger unit  240  is then placed, with its rightward ( FIG. 2 ) pivot stub  243  located in the corresponding boss  244  in the rightward housing part  15 , and its arm  251  inserted through the hole  252  ( FIG. 4A ) into the interior of the handle portion of the rightward housing part  15 , as seen in  FIGS. 4 and 4A . The trigger arm  251  is “covered” by the rear portion  281  of the suction hose  280  in  FIG. 3 . The electrical contacts  262  and  263  are placed on their respective posts  255  and  256  in the rear portion of the rightward housing part  15  and the three forward electrical connectors  175  are secured respectively to the mentioned contacts  262  and  263  and the motor contact  271  ( FIG. 4A ). Thereafter, the leftward ( FIG. 2 ) housing part  14  can be snap fitted to the rightward housing part  15  to close same and enclose the above mentioned apparatus, shown in  FIG. 3 , therein. 
   In the thus assembled handpiece, the drive unit is fixedly located by engagement of its drive axis bosses  84  and  85  ( FIG. 5 ) in corresponding bosses in the housing parts  14  and  15  (see for example at  96  in housing part  15  in  FIG. 2 ). Location of the drive unit  25  is assisted by the ribs  95  within the housing parts  14  and  15  and by snug resilient engagement of the drive unit  25  by the hoses  160  and  280  which flank it. 
   The drive unit shell  26  is configured to maintain the proper tolerances between meshing gears and related parts. Location of all the drive unit parts in the drive unit shell  26  reduces the need to maintain close tolerances in the larger and less specialized handle housing  11 . Even the housing tolerances, for locating the pump unit  100  with respect to the drive unit  25  in the housing  11 , need not be close since the bellows  101  are flexible enough to bend or otherwise distort to absorb minor mis-alignment or angulation of the reciprocation axis of the link member  51  with respect to the length axis of the pump unit  100 . Indeed, the ribs  95  in the housing  11  permit pivoting of the drive unit  25  about the axis of the bosses  96  to allow the drive unit  25  and pump unit  100  to settle into their own working relative orientation. Accordingly, the precision in the handpiece housing  11  can be concentrated in aspects of fitting together of the two housing halves. 
   The electric power supply unit  190  ( FIG. 22 ) is quickly and easily assembled. More particularly, the feet of the respective battery contacts  210 ,  211 ,  212  ( FIGS. 26–28 ) are slid downward into their respective grooves ( FIGS. 23A and 23B ) in the pan  192  ( FIG. 22 ) with their protruding toes resiliently gripping the sides of the grooves. The rear connectors  176  are connected to the battery contact fingers  224  and  225  in the order shown in  FIG. 22A . The batteries B 1 –B 8  are then slipped down into the pan in the orientation shown in  FIG. 22  and into electrically conductive engagement with the battery contacts  210 ,  211  and  212  indicated in  FIG. 22A . The rear portion of the liquid hose  160  is laid atop the batteries as indicated in  FIG. 23 , with the square flange  182  nonrotatable in the boss  235 , and the cover  193  is snap fitted atop the liquid hose  160  and battery filled pan  192 , as shown in  FIG. 23 , to complete assembly of the power supply unit. The cap  185  is pressed onto the sharpened tip  184  to protect it prior to use. 
   The result is a disposable pulsed irrigation handpiece unit which is entirely self-contained, including its own power supply, and which is ready for use upon having its sharpened tip  184  plugged into a conventional irrigation liquid supply bag or the like, and a conventional manner. 
   It should be noted that virtually the entire handpiece  10  and power supply unit  190  can be assembled without need for any adhesives, the parts going together with friction or snap fits or, in the case of the joinder of the bellows housing  104  to the bellows  100  and elbow  151 , by being held together by surrounding structure which in turn is snap fitted together. This greatly eases and speeds assembly. A minor exception is that the fitting  180  is here adhesively fixed to the hose  160 . 
   To use the handpiece assembly in surgery, the cap  185  ( FIG. 23 ) is removed from the pointed tip  183 , which is then plugged into a standard output fitting on a conventional irrigation liquid supply bag. The power supply unit  190 , being fixed to the rear end of the irrigation liquid hose  160 , can be allowed to simply hang from the irrigation liquid supply bag (not shown but schematically indicated at S in  FIG. 22 ). By providing a substantial length of irrigation liquid hose  160  (for example 10 feet), the liquid supply bag S and power supply unit  190  can be located well out of the way of the surgical team during use of the handpiece  10  at the surgical site. Even then, the power supply unit  190  is compact as compared to the adjacent conventional irrigational liquid supply bag (being very little larger than the eight conventional double AA batteries that it houses). 
   If suction will be desired at the surgical site, the handpiece nipple  283  ( FIG. 3 ) can be connected by a conventional hose not shown to a conventional suction source SS ( FIG. 3 ). 
   A variety of tip units  291  of differing characteristics (e.g. differing irrigation liquid spray patterns, etc.) may be made available for alternative mounting on the handpiece  10 . One example is shown in  FIGS. 8 ,  8 A and  8 B. 
   In any event, the user selects a tip unit  291  having a wand  294  of desired configuration, and rearwardly inserts its coupling  292  into the front end of the handpiece  11 . More particularly, the nipples  301  and  306  of the tip unit are inserted coaxially rearwardly, in sealed relation (see  FIG. 8 ) in the conduits  143  and  286  respectively of the bellows housing  104 . The resilient latch arm  312  enters the barrel  13  of the handpiece housing  11  adjacent to the bellows housing  104  until the plate  320  of the front cover  293  abuts the front end of the handpiece housing barrel  13 . In the last part of this tip installation movement, the wedge shaped ridge  313  ( FIG. 8 ) on the latch arm  312  snaps past the rib  314  of the housing barrel  13  to positively prevent forward removal of the tip unit from the handpiece. 
   To use the apparatus for irrigation of a surgical site, the user grips the handpiece, either by the handle  12 , in a pistol-like manner, or where the barrel  13  joins the handle  12 , in a wand like manner. In either position, the user has one or more fingers that can bear on and press inwardly the trigger lever  242  from its inoperative rest position shown in solid line in  FIG. 4A  forward and through its low speed and high speed positions indicated in broken lines at  253 B and  253 C in  FIG. 4A . In the first operative position  253 B, the blade  253  connects the low speed (here six-volt) contact  266  to the motor contact  270 . On the other hand, in the fully depressed condition of the trigger, indicated at  253 C, the blade  253  connects the high speed, 12 volt contact  267  with the motor contact  270 . Accordingly, the user can select between “off”, lower power pulsing and high power pulsing. 
   In one embodiment pump stroke was about ¼″. In one embodiment shown, the motor speed was about 15,000 rpm and the speed reduction afforded by the transmission was about 15-1, providing the eccentric with about 1,000 rpm speed. 
   Depending on the flow resistance of the particular tip unit attached to the handpiece, the liquid pulse frequency may change. In one example, a handpiece according to the invention produced about 1200 pulses per minute, dispensing about 1600 ml per minute of irrigation liquid in about 1.3 ml liquid pulses. The positive drive of the pump unit by the drive unit and the location of the pump unit, near the front end of the barrel  13  and in direct engagement with the tip unit, provides liquid pulses at the output of the tip unit which have sharp rise and fall slopes. Thus, the relationship of liquid pulse amplitude to time approximates a square wave form, more so than for example, the aforementioned device of U.S. Pat. No. 5,046,486. Further, the force applied to the pulses by the present apparatus is higher (somewhat above one Newton) than in that prior art device, at the full power position of the trigger. 
   In one embodiment according to the invention, a tab  316  ( FIGS. 1 and 8B ) extends forward from the front plate  320  of the front cover  293 , on the opposite side of the wand  294  from the latch arm  312 . To release the latch arm  312  from the housing  11 , the user can thus simply simultaneously grip with opposite fingers and pinch toward each other the latch arm  312  and tab  316 . In other words the tab  316  provides base toward which to pinch, or pull, the latch arm  312  to release the tip unit  291  from the handpiece  11 . 
   In the present invention, the liquid and suction nipples of the tip unit connect directly to the pump unit  100 , and do not contact any part of the handpiece housing  11 . Accordingly, neither the pump unit  100  nor tip unit  291  need fit with close tolerances the handpiece housing  11 . The connection of the tip unit to the handpiece housing is merely to latch the tip unit against loss from the handpiece housing and to casually cover the open front end of the handpiece housing. Accordingly, the liquid tight fit is between the nipples of the tip unit and conduits of the pump unit, not with the housing. 
   Although a particular preferred embodiment of the invention has been disclosed in detail for illustrative purposes, it will be recognized that variations or modifications of the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention.