Patent Publication Number: US-7587831-B2

Title: Can opener

Description:
PRIORITY CLAIM 
   This application claims the benefit of prior U.S. patent application Ser. No. 10/996,992, filed Nov. 23, 2004 which claims the benefit of prior United Kingdom application Serial Number 0421717.0 filed Sep. 30, 2004, contents of which are incorporated herein. 
   FIELD OF THE INVENTION 
   The invention relates to a manually operable can opener. 
   BACKGROUND OF THE INVENTION 
   Can openers have been known for many years, and the typical construction includes a traction wheel for turning a can and a disc-like cutter blade for rotation while the can is being turned to cut open the can. Conventionally, the traction wheel is turned by means of an operating member mostly in the form of a wing knob. Can openers that can be operated by pivoting a lever or the like are not new, for example as disclosed in published patent specifications GB 613,146, U.S. Pat. No. 5,970,618, WO 03/043,929 A1 and U.S. 2002/0088127 A1. None of these can openers survive for various reasons, probably mainly because that they are not reliable in construction or operation and/or are difficult to use. 
   The invention seeks to obviate or at least alleviate some of such shortcomings by providing a new or improved can opener. 
   SUMMARY OF THE INVENTION 
   According to a preferred form of the invention, there is provided a can opener comprising first and second handle members pivotal with respect to each other, and a rotatable traction wheel and a rotatable cutter blade movable by the first and second handle members respectively between an inoperative position in which the wheel and the blade are spaced apart for receiving an edge of a can to be opened and an operative position in which the wheel and the blade are close together for turning and cutting the edge of said can. An operating member is supported for pivotal reciprocation relative to the handle members. Also included is a ratchet assembly arranged to be driven by the operating member upon reciprocation for operating the traction wheel and the cutter blade. The ratchet assembly comprises a ratchet wheel in engagement with the traction wheel and a spring-loaded pawl movable by the operating member for turning the ratchet wheel in a driving direction upon reciprocation of the operating member. The pawl has front and rear portions taken in the driving direction, with the front portion in engagement with the operating member and the rear portion engageable with the ratchet wheel for turning the ratchet wheel. 
   Preferably, the pawl lies generally parallel and close to an adjacent periphery of the ratchet wheel. 
   It is preferred that the rear portion of the pawl comprises a hook-shaped end for engaging the ratchet wheel. 
   Preferably, the ratchet assembly includes a spring acting upon the pawl at its rear portion for resiliently biasing the pawl into engagement with the ratchet wheel. 
   It is preferred that the operating member is pivotable about an operating axis and is spaced apart from the ratchet assembly in a direction parallel to the operating axis. In a preferred embodiment, the ratchet assembly includes a base on which the ratchet wheel and the pawl are held, the base being pivotable by the operating member upon reciprocation. 
   More preferably, the base is fixedly connected to the operating member by means of a shaft that extends along the operating axis. 
   It is advantageous that the ratchet assembly is positioned between the operating member and the traction wheel in a direction parallel to the operating axis. 
   Preferably, the operating member is pivotable and the traction wheel rotatable about the same axis. 
   In a preferred embodiment, the first and second handle members have respective frontmost ends that are pivotably connected, and the operating member is pivotably connected to the first handle member at a position to one side thereof and falling short of its frontmost end. 
   More preferably, the first and second handle members have respective front end portions which together expand into a bulbous chamber locating the ratchet assembly and to which the traction wheel and the cutting blade are individually attached. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred and alternative embodiments of the present invention are described in detail below with reference to the following drawings. 
     The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which: 
       FIG. 1  is a left side view of an embodiment of a can opener in accordance with the invention; 
       FIG. 2  is a cross-sectional view of the can opener of  FIG. 1 , taken along line II-II; 
       FIG. 3  is a front end view of the can opener of  FIG. 1 ; 
       FIG. 4  is a top plan view of the can opener of  FIG. 1 ; 
       FIG. 5  is a cross-sectional view of the can opener of  FIG. 4 , taken along line V-V; 
       FIG. 6  is a cross-sectional view of the can opener of  FIG. 1 , taken along line VI-VI; 
       FIG. 7  is an exploded perspective view of the can opener of  FIG. 1 ; 
       FIG. 8  is a cross-sectional view in part of  FIG. 5 , showing one operating condition of the can opener; and 
       FIG. 9  is a cross-sectional view similar to  FIG. 8 , showing another operating condition. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to the drawings, there is shown a can opener  100  as an exemplary embodiment of the invention, which comprises a pair of bottom and top elongate handle members  110  and  120  hinged together at their frontmost ends  111  and  121  for pivotal movement with respect to each other, and a rotatable traction wheel  200  and a rotatable cutter blade  300  mounted behind the frontmost ends  111  and  121  of the bottom and top handle members  110  and  120  respectively for movement thereby. The wheel  200  and the blade  300  are movable between an inoperative position in which the wheel  200  and the blade  300  are spaced apart for receiving an edge of a can to be opened and an operative position in which the wheel  200  and the blade  300  are close together for turning and cutting the edge of the can. 
   The top handle (as shown in the orientation of  FIG. 7 ) includes a channel or slot  127  that is configured to receive a corresponding tab  126  formed in the bottom handle, with each of the slot and tab being located forward of the wheel and blade. A pin  128  extends through a bore in the tab and slot to pivotally join the handle halves together. 
   Both handle members  110  and  120  are made sufficiently broad and to have an oval cross-section jointly for easy and comfortable gripping by a user. Their front end portions  115  and  125  together expand to form a bulbous chamber  130 , to which the traction wheel  200  and the cutting blade  300  are individually attached. The wheel  200  and the blade  300  are rotatable about respective axis X and Y. They are fitted with respective co-axial gearwheels  210  and  310  for mating in the operative position such that the blade  300  will rotate simultaneously with the wheel  200 , when the latter is being rotated by the user. Axis X lies horizontally during normal use of the can opener  100 , whereas axis Y extends at small acute angle downwardly with respect to axis X. 
   The can opener  100  includes an operating lever  400  supported for pivotal reciprocation relative to the handle members  110  and  120 , and a ratchet assembly  500  arranged to be driven by the lever  400  upon reciprocation for operating the traction wheel  200  and the cutter blade  300 . The lever  400  is connected at its lower end  410  to the bottom handle member  110  at a position to the right side thereof and falling short of its frontmost end  111 , for pivotal movement about axis X. 
   The ratchet assembly  500  has a ratchet wheel  510  in co-axial engagement with the traction wheel  200 , a pawl  520  movable by the operating lever  400  for turning the ratchet wheel  510  in a driving direction D upon reciprocation of the lever  400 , and a spring  530  resiliently biasing the pawl  520  into engagement with the ratchet wheel  510 . Also included are a base plate  540  on which the ratchet wheel  510  and the pawl  520  are held and a generally flat casing  550  (having a left side lid  551 ) encasing all the other ratchet components  510  to  540 . 
   The ratchet assembly  500  is fitted in the handle chamber  130 , being largely located within the bottom handle portion  115 . The base plate  540  is connected by an integral transverse shaft  541  to the lower end  410  of the operating lever  400  for pivotal movement thereby, said shaft  541  extending along axis X through a right side support hole of the casing  550  and the bottom handle portion  115 . By means of the shaft  541 , the lever  400  is spaced apart from the ratchet assembly  500  in a direction parallel to axis X. 
   The ratchet wheel  510  has a transverse shaft  511  which extends along axis X through a left side support hole of the casing  550  and the bottom handle portion  115 , on which shaft  511  externally the traction wheel  200  and associated gearwheel  210  are mounted fast for rotation with the ratchet wheel  510 . The ratchet assembly  500  is positioned between the operating lever  400  and the traction wheel  200  in a direction parallel to axis X. 
   Whilst the ratchet wheel  510  and shaft  511  are molded from plastics material, the wheel  510  is reinforced by a metal wheel  512  fixed against its side of identical shape and size for co-operation with the pawl  520  that is made of metal. The base plate  540  includes a flat integral boss  542  centered at axis X about which the strengthening wheel  512  is disposed, whereby the ratchet wheel  510  is also rotationally supported on its inner side. 
   A horizontal leaf spring  141  at the top of the ratchet casing  550  urges the top handle member  120  to pivot away from the bottom handle member  110  to facilitate mounting of the can opener  100  onto the edge of a can. A latching knob  142  supported by a vertical leaf spring  143  from the casing  550  is engageable with the top handle member  120  through a hole  144  thereof to lock the top handle member  120  close upon the bottom handle member  110  against the action of the spring  141  to facilitate holding the two handle members  110  and  120  together during cutting operation. The knob  142  includes a lower forward surface  145  that abuts a corresponding shoulder or upper surface  146  formed within the hole  144  on the upper handle  120 . The leaf spring  143  biases the knob  142  forward and against the shoulder to maintain the handles in a locked position, while a tail  148  formed on the knob abuts an inner surface on the upper handle. To unlock the handles, the knob is downward and rearward, disengaging it from the forward shoulder  146  so that it can retract through the hole  144 . 
   The pawl  520  has a straight front end  521  and a crooked or hook-shaped rear end  522 , taken in the driving direction D. The pawl  520  is hinged at its front end  521  at an off-center position (from axis X) to the base plate  540  for to-and-fro arcuate movement by the operating lever  400  (through cranking) about the ratchet wheel  510  rotatable about the center (axis X). In the driving direction D, the rear pawl end  522  engages like a hook with the asymmetrical teeth of the ratchet wheel  510  for turning the wheel  510 . In the opposite direction, the rear pawl end  522  will upon return ride past the teeth of the ratchet wheel  510  without turning the wheel  510 . In all, the ratchet wheel  510  (and hence the traction wheel  200  and cutter blade  300 ) will be turned stepwise in one direction D upon pivoting of the operating lever  400  in opposite directions. 
   Whilst the pawl  520  is hinged at its front end  521 , the spring  530  acts directly upon the rear end  522  for optimal resilience to keep it in engagement with the teeth of the ratchet wheel  510 . As the pawl  520  turns the ratchet wheel  510  by its rear end  522  through a pulling action, the chance that the pawl  520  gets jammed is remote. By lying generally parallel and close to the adjacent periphery of the ratchet wheel  510 , the pawl  520  does not only take up minimum space but also turns the wheel  510  by acting almost tangentially thereupon to reduce loss of force in the radial direction. 
   The base plate  540  supports the ratchet wheel  510 / 512  and pawl  520  with spring  530  for pivotal movement within the casing  550 , whose interior has a cross-section that restricts the pivotal movement of the base plate  540  and hence the operating lever  400  between rearmost ( FIG. 8 ) and foremost ( FIG. 9 ) positions spaced apart for just over an angle of 90° as shown. More specifically, an outer shoulder of the base plate  540  will at either extremity hit the peripheral wall of the casing  550  in that direction. In the preferred form, this limiting function is accomplished by the relative shapes of the base plate and the housing. It should be appreciated that a wide range of structures are contemplated in which a “shoulder” or other abutment of the base plate  540  can engage a stop or other surface within the casing  550  in order to limit rotational movement. 
   In operation, the can opener  100  is held by the left hand of a user grasping the two handle members  110  and  120 , and the operating lever  400  is pivoted back-and-forth by the right hand. Every time the lever  400  is pivoted forward, the ratchet wheel  510  is turned by the pawl  520  to rotate the traction wheel  200  and cutter blade  300 , thereby cutting open a can along its top edge. As the user can, and will, keep holding the lever  400  while pivoting it back-and-forth, operation is made easy. 
   The can to be opened is clamped by the wheel  200  and blade  300  on the left side of the can opener  100 , that being a load on the left hand side of the can opener  100 . The can opener  100  is operated by a user pivoting the lever  400  on the right hand side. The point of application of user&#39;s force is extended to the right (by means of the shaft  541 ) and this somewhat balances the load to the left, thereby making the can opener  100  feel more stable in use. 
   It is envisaged that the operating lever may be connected to the top handle member, in which case gears may be used between the lever and the ratchet assembly (in the bottom handle member) for transmitting drive across the handle members. In another aspect, more than one pawl may be used to turn the ratchet wheel for example two on opposite sides, and this offers balance and/or strength in drive transmission. 
   The invention has been given by way of example only, and various other modifications of and/or alterations to the described embodiment may be made by persons skilled in the art without departing from the scope of the invention as specified in the appended claims. 
   The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows.