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BACKGROUND OF THE INVENTION 
   1) Field of the Invention 
   The invention relates to a wafer-type tumbler cylinder, the cylinder shaft of which facilitates the placement of the wafers and springs and, furthermore, one spring is positioned in a relatively wider rectangular notch, thereby serving as a shared spring for every two wafers. The amount of spring is reduced by half and it&#39;s able to prevent from prying or unlocking. Moreover, it&#39;s more convenient for lock makers to make and assemble various cylinders in different shapes or different length. 
   2) Description of the Prior Art 
   Conventional wafer-type tumblers, as shown in  FIG. 14 , are typically comprised of a sleeve  1   a , a cylinder  2   a , and a plurality of wafers  3   a  and their springs  4   a . The sleeve  1   a  consists of a sleeve body  10  having a bore  11  extending through it lengthwise, a minimum of one lengthwise slot  12  disposed along the inside of the bore  11 , and a bearing edge  13  at the leading end of the bore  11 . As shown in  FIG. 15 , the cylinder  2   a  has a keyway  21  through the center and, furthermore, a flange  22  and a drive section  23  at the front and rear ends, with a shaft  20  movably installed in the bore  11  of the sleeve  1   a ; the shaft  20  has disposed one or more diametrically oriented, rectangular through-holes  24  and, furthermore, at the two sides of each rectangular through-hole  24  is a C-shaped recess  25  and a horizontally oriented U-shaped recess  26  (as shown in  FIGS. 16 and 17 ), for the installation of one or more wafer  3   a  and spring  4   a  sets. The cylinder  2   a , after the installation of the wafers  3   a  and their springs  4   a , is first fitted into the bore  11  of the sleeve  1   a  and, furthermore, such that the one end of each wafer  3   a  is subjected to the elastic force of its spring  4   a , and then postured against and inserted into the slot  12  inside the bore  11 , thereby obstructing the clockwise and counter-clockwise rotation of the cylinder  2   a  situated in the bore  11 ; at the same time, the flange  22  at the front end of the cylinder  2   a  is seated on the bearing edge  13  at the leading end of the bore  11  in order to inset securely the bore  11 ; additionally, the drive section  23  at the rear end of the cylinder  2   a  is mounted with a lock tool or electric driver so as to check whether the tumbler is locked or electrified. 
   Because each wafer  3   a  of the conventional wafer-type tumbler, in addition to a window  31  in the middle thereof, has an opposing spring tab  32  and a locating tab  34 ; when the wafer  3   a  is inserted into each rectangular through-hole  24  on the shaft  20  of the cylinder  2   a , it is first necessary to install a spring  4   a  into the C-shaped recess  25  at one side of the rectangular through-hole  24 , following which the wafer  3   a  is then inserted into the rectangular through-hole  24 ; but during the installation, since the wafer body  30  of the wafer  3   a  has the spring tab  32 , its insertion occurs without any resistance along the C-shaped recess  25 ; however, the locating tab  34 , disposed in the other side of the wafer body  30 , must similarly undergo insertion through the C-shaped recess  25  along the rectangular through-hole  24 , and, as a result, friction occurs along the interior wall of the rectangular through-hole  24  at the lateral extent of the C-shaped recess  25 , and only after this does the wafer body  30  reach into the horizontally oriented U-shaped recess  26 , where it becomes nested onto the bottom of the horizontally oriented U-shaped recess  26  (as shown in  FIGS. 16 and 17 ), and also only then is the cylinder  2   a  installed in the bore  11  of the sleeve  1   a , which completes the assembly of one wafer-type tumbler mechanism. As such, during the insertion of each wafer  3   a  into the rectangular through-hole  24  on the shaft  20 , the operation is difficult and adversely affects the production process. After each wafer  3   a  has been inserted into the rectangular through-hole  24 , the locating tab  34  on the wafer body  30  is nested onto the bottom of the horizontally oriented U-shaped recesses  26 ; however, the height of the locating tab  34  is quite limited and, furthermore, the locating tab  34  is subjected to the outwardly exerted elastic force of the spring  4   a , the wafer  3   a  is often ejected out of the rectangular through-hole  24 . Such situation results in a troublesome and inconvenient assembly operation as the cylinder  2   a  is inserted into the bore  11  of the sleeve  1   a , which likewise adversely affects the production process. 
   Moreover, based on the locking and unlocking structure of the conventional wafer-type tumbler, it depends entirely on the installation of the shaft  20  on the cylinder  2   a  with a plurality of wafers  3   a ; hence, as indicated in  FIG. 15 , the rectangular keyway  21  must be disposed through the center of the shaft  20  to facilitate insertion of the serrated blade  51  on the key  5   a  (as shown in  FIG. 19 ), which causes each wafer  3   a  extending into the end of the slot  12  in the bore  11  to fully react within the outer diameter of the shaft  20 , thereby achieving the objective of locking or unlocking. Since the cylinder  2   a  of the conventional wafer-type tumbler is typically made of aluminum-zinc alloy material in an integrated molding process, and the keyway  21  disposed through the center of the shaft  20  also penetrates the internal section of the shaft  20 ; as a result, it is not possible to mold a corrugated keyway having a narrow width. It&#39;s only possible to mold a keyway with a width of 1.5 mm or more, and as indicated in  FIG. 14 , the shape of the keyhole  211  only can be formed as reverse Z-shaped or other similar contour, which has a triangular projecting element  212  at the two lateral inner sides of the keyhole  211  respectively (one triangular projecting element is concealed by the flange  22 , so it&#39;s not viewable); the keyway  21  along the internal section of the shaft  20  not only is formed as relatively wide rectangular shape, but also has disposed at most one lengthwise triangular projecting element  212  at one side of the keyway  21 , as indicated in  FIGS. 15 and 18 . As a result, the prior art is easily broken by thieves and pried or unlocked by burglars. 
   Due to the shape of the keyway  21  and its keyhole  211  on the shaft  20  of the cylinder  2   a  in the conventional wafer-type tumbler, the design of which is formed as relatively wide rectangular and reverse Z-shaped contour, and furthermore, the two triangular projecting elements  212  are disposed in opposing position and at close distance along the two lateral inner sides of the keyhole  211 ; therefore, the serrated blade  51  of the key  5   a  must be fabricated of a thicker metal plate. Even though the whole key  5   a  may be formed by punching the metal plate, the serrated blade  51  (as indicated in  FIGS. 19 and 20 ) must undergo milling or planing process to form as reverse Z-shaped section by means of a miller or planer, and it also has to undergo cutting or milling process to make a lengthwise V-shaped groove  511  at each of the lateral sides. Therefore, in terms of production, the process is extremely inconvenient and, furthermore, both time and labor consuming. 
   In view of the serrated blade  51  of the conventional wafer-type tumbler cylinder, there are such inconveniences and shortcomings during the process of production and assembly; such production cost is greater and not cost-effective and also the theftproof capability of the prior art still remained deficient, so the inventor of the invention herein conducted research which culminated in the improved wafer-type tumbler cylinder of the present invention. 
   SUMMARY OF THE INVENTION 
   The objective of the invention herein is to provide a wafer-type tumbler cylinder having a spring positioned in a relatively wider rectangular notch to serve as a shared spring for every two wafers. The amount of spring is reduced by half and the theftproof capability is much improved. 
   Another objective of the invention herein is to provide a wafer-type tumbler cylinder that is easily made and assembled into different shapes or different length of cylinder. It is cost-effective for lock makers to save the production cost of molds. 
   To achieve the first objective of the invention herein, the shaft of the cylinder consists of a first and a second semicircular columnar body that are insertionally conjoined into an integration, and furthermore, respectively disposed at the front and rear ends of the first semicircular columnar body are a flange and a drive section; although, on the inner lateral surfaces of the first and second semicircular columnar bodies, one or more rightward and leftward U-shaped slots are disposed; only disposed in every two rightward or leftward U-shaped slots is a relatively wider rectangular notch. As a wafer is installed in each of the two rightward (or leftward) U-shaped slots, a spring is positioned in the relatively wider rectangular notch to serve as a shared spring for every two wafers. The material cost of a spring is saved; besides, it&#39;s able to prevent from prying effectively because a burglar can not pry two wafers supported by a shared spring. 
   Another embodiment of shaft of the cylinder consists of a first and a second semicircular columnar bodies with identical shape and dimension, which are combined into an integration; furthermore, a semicircular tenon (or semi-rectangular or other shaped tenon) respectively disposed at the front and rear ends of each said semicircular columnar body enables, following the installation with a plurality of wafers and their springs, the respective fitting of a sleeve ring and a drive section onto the front and rear ends to thereby assemble one shaft. As such, it&#39;s convenient to produce and assemble different numbers of wafers into different length of shafts, and as different shapes of inner hole of the sleeve ring and the corresponding shape of cavity of the drive section are fitted thereon, it is quite convenient to manufacture longer or shorter shafts so as to assemble the wafer-type tumblers with different length or different shapes. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded drawing of the wafer-type tumbler of the invention. 
       FIG. 2  is an exploded drawing of the wafer-type tumbler cylinder of the invention. 
       FIG. 3  is a cross-sectional view of the invention herein when the wafer-type tumbler is not installed with wafers and when the serrated blade of the key is inserted. 
       FIG. 4  is cross-sectional view of the invention herein when the wafer-type tumbler is interlocked. 
       FIG. 5  is a cross-sectional view as the wafer-type tumbler is installed with one wafer and its spring. 
       FIGS. 5-1  is a cross-sectional drawing, as viewed from a perspective in  FIG. 5 , to show the adjacent wafer and its spring of the invention herein. 
       FIG. 6  is an orthographic drawing of the wafer-type tumbler key of the invention. 
       FIG. 7  is a cross-sectional drawing of the serrated blade of the wafer-type tumbler key. 
       FIG. 8  is an isometric drawing of the preferred embodiment of the cylinder in the present invention. 
       FIG. 9  is an exploded drawing of the preferred embodiment of the cylinder in the present invention. 
       FIG. 10  is a cross-sectional drawing of the invention herein, as viewed from the perspective of line  10 ˜ 10 ′ in  FIG. 8 . 
       FIG. 11  is an exploded drawing of another preferred embodiment of the cylinder with wafers and a spring. 
       FIG. 12  is a vertically sectional view of the cylinder as viewed from the perspective in  FIG. 11 . 
       FIG. 13  is a cross-sectional drawing of the invention herein, as viewed from the perspective of line  13 ˜ 13 ′ in  FIG. 12 . 
       FIG. 14  is an exploded drawing of the conventional wafer-type tumbler. 
       FIG. 15  is a cross-sectional drawing of the conventional wafer-type tumbler when the wafers are not installed. 
       FIG. 16  is a cross-sectional drawing of the conventional wafer-type tumbler wherein a wafer and it spring are disposed. 
       FIG. 17  is a cross-sectional drawing, as viewed from a perspective in  FIG. 16 , to show the adjacent wafer and its spring. 
       FIG. 18  is a cross-sectional view of the conventional wafer-type tumbler when the serrated blade of the key is inserted. 
       FIG. 19  is an orthographic drawing of the conventional wafer-type tumbler key. 
       FIG. 20  is a cross-sectional view of the serrated blade of the key in the conventional wafer-type tumbler. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to  FIG. 1 , the wafer-type tumbler of the invention herein, in common with the above-mentioned conventional wafer-type tumbler, is comprised of a sleeve  1 , a cylinder  2 , a plurality of wafers  3  and their springs  4 ; the structure of the sleeve  1  and the method for installing with the cylinder  2  are the same as those of said conventional wafer-type tumbler. There is no need to go into details. However, a shaft  20  of the cylinder  2 , as shown in  FIG. 2 , consists of a first and a second semicircular columnar body  20   a  and  20   b  that are integrated with each other; furthermore, respectively disposed at the front and rear ends of the first semicircular columnar body  20   a  are a flange  22  and a drive section  23 ; at the inner lateral surface between said flange  22  and drive section  23  is a transversely U-shaped indentation  201 , the length of which matches with the second semicircular columnar body  20   b  so as to complete the assembly of the shaft  20  on the cylinder  2  (as indicated in  FIG. 1 .) On the inner lateral surfaces of the first and the second semicircular columnar body  20   a  and  20   b , one or more rightward U-shaped slots  24   a  and leftward U-shaped slots  24   b  are disposed for the installation of said wafers  3 ; however, only in each of the rightward U-shaped slots  24   a  on said first semicircular columnar body  20   a  is disposed a rectangular notch  27  matching the dimension of the spring  4 , thereby facilitating the placement of each wafer  3  and its spring  4  into each said U-shaped slot  24   a  and said rectangular notch  27  on said first semicircular columnar body  20   a , following which the second semicircular columnar body  20   b  is then fitted thereon for an integral unity; after that, the shaft  20  of said cylinder  2  is inserted into a shaft hole  11  in said sleeve  1  to assemble the wafer-type tumbler of the present invention, as illustrated in  FIG. 5  as well as  FIGS. 5-1 . 
   When said first and second semicircular columnar body  20   a  and  20   b  are molded into shape, two half-keyways  21   a  and  21   b  are formed as corrugated contour in the center of the inner lateral surfaces thereof, furthermore, one or more posts  28  (as shown in  FIG. 2 ) and holes  29  (which are concealed by the second semicircular columnar body  20   b , so please refer to  FIG. 4 ) are disposed at the front and rear ends of each said inner lateral surface. As such, the second semicircular columnar body  20   b , via the insertion of said posts  28  through said holes  29 , is correspondingly fixed with the first semicircular columnar body  20   a  into a unity so as to complete the assemblage of the cylinder  2 , as indicated in  FIGS. 1 ,  3  and  4 ; at the same time, along the common center of the first and second semicircular columnar body  20   a  and  20   b , a keyway  21  (as shown in  FIG. 4 ) is formed as corrugated contour, with a narrower width of 0.5 mm, thereby preventing theft by means of a metal sheet or other equivalent tool inserted for burglarizing. 
   Since the keyway  21  disposed at the center of the cylinder  2  is approximately 0.5 mm in width and is fabricated as corrugated passage, a serrated blade  51  of a key  5  (as depicted in  FIGS. 6 and 7 ) is produced by directly punching an approximately 0.5 mm or thinner metal plate, and a plastic grip  52  is coated onto the opposite end thereof, thereby facilitating the user holding the key for locking and unlocking the wafer-type tumbler; it is not necessary to mill and plane any lengthwise grooves nor other milling and planing processes. To facilitate the insertion of said very thin serrated blade  51  into the keyway  21  in the shaft  20  of the cylinder  2 , it is then necessary, in the center of the flange  22  at the front end of said shaft  20 , to dispose a rectangular, flared keyhole  211  that is in line with said keyway  21 . As for the drive section  23  at the rear end of said shaft  20 , in addition to the depiction shown in  FIG. 1  and  FIG. 2  wherein the drive section  23  is shaped as square or rectangular rod body  230 , said drive section  23  may be shaped as threaded, circular, oblate, tubular or other shaped rod body (not shown in the drawings) to make the design of said drive section  23  match with a lock tool or electric driver, thereby enabling said drive section  23  to fasten with said lock tool or electric driver by means of screws or rivets. 
   Furthermore, since the wafers  3  of the wafer-type tumbler of the invention herein do not require mounting in rectangular through-holes  24  (as depicted in  FIG. 14 ), said wafers  3  can be fixed on said shaft  20  securely, as shown in  FIG. 1 , by a window  31  formed in the center of each wafer body  30  along with a spring tab  32  at one side thereof, and there is no need to dispose any locating tab thereon. 
   Referring to  FIGS. 8 and 9 , these two figures are isometric and exploded drawings of the preferred embodiment of a cylinder  2 ′ of the present invention. A shaft  20  on the cylinder  2 ′ consists of a first and a second semicircular columnar body  20 ′ a  and  20 ′ b  (both of identical shape and dimension) that are conjoined into an integral unity; furthermore, respectively disposed at the front and rear ends of each semicircular columnar body  20 ′ a  and  20 ′ b  is a semicircular tenon  202  and  203  which is respectively fitted onto a sleeve ring  22   a  and a drive section  23  to constitute a cylinder  2 ′, as indicated in  FIG. 8 . The said semicircular tenons  202  at the front ends of said semicircular columnar body  20 ′ a  and  20 ′ b  are correspondingly coupled to form a complete tenon, and the said semicircular tenons  203  at the rear ends thereof are correspondingly coupled to form a complete tenon. To enable the precise placement of the sleeve ring  22   a  and the drive section  23  onto the front and rear ends of the integrated semicircular columnar bodies  20 ′ a  and  20 ′ b , as well as to prevent dislodging and comparative rotation, the sleeve ring  22   a  has an inner hole  221  in a ring body  220   a , which is a D-shaped hole with a minimum of one secant planar edge  222  along one lateral wall, and furthermore, an opening  223  through one side of the ring body  220   a , wherein the center of said opening  223  is aligned and parallel with said secant planar edge  222 ; a facet  204  is disposed correspondingly along the outer extent of the semicircular tenon  202  of either the first or the second semicircular columnar body  20 ′ a  or  20 ′ b . As such, the complete tenon that is coupled by means of said semicircular tenons  202  at the front ends of said semicircular columnar body  20 ′ a  and  20 ′ b  is installed with the sleeve ring  22   a , and then a drill is used, through the opening  223 , to pierce into the front semicircular tenon  202  having said facet  204  thereof, thereby enabling the insertion of a pin  6  for securing and fixing, as depicted in  FIG. 10 . 
   Additionally, the drive section  23 , along the inner end of its square or rectangular rod body  230 , has an extended sleeve  231  so as to enable the conjoinment with the complete tenon coupled by means of the semicircular tenons  203  at the rear ends of said semicircular columnar body  20 ′ a  and  20 ′ b.    
   The extended sleeve  231  has disposed a D-shaped cavity  234  having a minimum of one secant planar edge  232  along the inner wall at one side thereof such that an aperture  233  is formed at one side of the extended sleeve  231 , of which the center is aligned and parallel with said secant planar edge  232 ; similarly a facet  204  is correspondingly disposed along the outer extent of the semicircular tenon  203  at the rear end of either the first or the second semicircular columnar body  20 ′ a  or  20 ′ b . As such, the semicircular tenons  203  are assembled into a complete tenon, which is installed with said extended sleeve  231 , and in common with the depiction shown in  FIG. 10  as well as previous arrangement, a pin  6   a  illustrated in  FIG. 9  is fixed with said extended sleeve. 
   As for the molding process of said first and second semicircular columnar bodies  20 ′ a  and  20 ′ b  with identical shape and dimension, the structural and installation arrangement of the corresponding half-keyways  21   a ,  21   b  and the rectangular notches  27 , the integration of more than one pair of posts  28  and holes  29 , as well as the arrangement of wafers  3  and their springs  4 , are the same with the first and second semicircular columnar body  20   a ,  20   b  of the cylinder  2  in the first embodiment of the invention herein; therefore, it shall not be further elaborated. Furthermore, the semicircular tenons  202  and  203  disposed on the two ends of the first and second semicircular columnar bodies  20 ′ a  and  20 ′ b , in addition to the shape of semicircle, they may also be shaped as semi-square, semi-rectangular, semi-hexagonal or semi-polygonal tenons, or even as semi-oval or semi-oblate tenons; moreover, the shape of the inner hole  221  in the ring body  220   a  of the sleeve ring  22   a  accords with that of the D-shaped cavity  234  in the extended sleeve  231  on the drive section  23 ; at the same time, the shape of the rod body  230  on said drive section  23  may also be disposed as threaded, circular, oblate, tubular or other shaped rod body (not shown in the drawings.) 
     FIG. 11  is an exploded drawing of another preferred embodiment of the shaft  20  of the cylinder  2 ′ in the invention herein with wafers  3  and a spring  4 . Said shaft  20  also consists of a first and second semicircular columnar body  20 ′ a  and  20 ′ b  with identical shape and dimension, which are conjoined into an integral unity, and the preferred embodiment of the semicircular columnar bodies  20 ′ a  and  20 ′ b , between every two rightward U-shaped slots  24   a  or every two leftward U-shaped slots  24   b  disposed in the inner lateral surfaces thereof, is modified by disposing a relatively wider rectangular notch  27 ′; meanwhile, each wafer  3  is modified by disposing a horizontal L-shaped tab  33  at one side of its wafer body  30 . As such, between every pair of (or every two) correspondingly rightward U-shaped slots  24   a  or leftward U-shaped slots  24   b  of each semicircular columnar body  20 ′ a  and  20 ′ b  is installed a wafer  3  respectively, and only one spring  4  is positioned in each relatively wider rectangular notch  27 ′, wherein said spring  4  is served as a shared spring for every two wafers  3   a  and  3   b , as shown in  FIGS. 12 and 13 . This embodiment of the shaft  20  of the cylinder  2 ′ can similarly be utilized in the preceding embodiment of the shaft  20  of the cylinder  2 .

Summary:
A wafer-type tumbler cylinder comprises a sleeve, a cylinder, some wafers and some springs. A shaft of the cylinder includes a first and a second semicircular columnar body. The first semicircular columnar body includes a front flange, a rear drive section and a U-shaped indentation at the inner lateral surface that provides for insertion into the second semicircular columnar body. On the first and second semicircular columnar bodies, one or more slots are disposed to fasten with the wafers. A relatively wider rectangular notch is disposed between the inner sides of every two slots, which are respectively installed with a wafer; only one spring is positioned in the wider rectangular notch, thereby serving as a shared spring for every two wafers. The material cost of a spring is saved; besides, it&#39;s able to prevent from prying effectively because a burglar cannot pry two wafers supported by a shared spring.