Patent Publication Number: US-6702158-B2

Title: Knocking-type liquid container

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a liquid container, and more particularly to a knock-type liquid container that holds a liquid such as cosmetic liquid, writing ink, or correcting liquid and has a liquid outlet provided at a tip portion of the container. 
     2. Description of the Related Art 
     A conventional liquid container that holds the above-mentioned type of liquid is disclosed in Japanese Patent Application (JPA) No. 2000-51919 applied for by the inventors of the present application. 
     This conventional knock-type liquid container aims to supply the liquid therein forwardly of the container by a user&#39;s knocking operation, and includes a tank, a piston, a threaded rod, a rotating cam, a knocking cam, and a knocking body. The tank holds a liquid therein and has a liquid outlet provided at the forward end thereof. The piston slides in the tank. 
     The threaded rod, integrally formed with the piston, extends rearwardly of the piston and has a male thread on its outer circumferential surface. The threaded rod is not rotatable relative to the tank. The rotating cam has a female threaded hole into which the male thread of the threaded rod is screwed. The knocking cam is disposed rearwardly of the rotating cam and causes the rotating cam to rotate in one direction. The knocking body is resiliently urged rearwardly relative to the knocking cam and is operated to perform a knocking operation. One of the knocking body and the knocking cam has a projection formed thereon and the other of the knocking body and the knocking cam has a beveled path that inclines in the axial direction and fittingly receives the projection. Knocking the knocking body causes the knocking cam to rotate, thereby causing the rotating cam to rotate. 
     This configuration allows the liquid to be supplied by a knocking operation of the knocking body. The configuration is advantageous in that the knocking operation requires only a one-hand operation, thereby providing good operability. 
     However, because of the simple nature of the knocking action, the knocking body may be knocked inadvertently, thereby causing the piston to advance forwardly to discharge the liquid from the tank. Therefore, conventionally, to prevent the knocking body from being inadvertently knocked, the force required to knock the knocking body should be sufficiently large (e.g., about 12.7 N=1.3 kg weight). However, such a relatively large force impairs the operability of the knocking body. This is a problem. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing and other problems, drawbacks, and disadvantages of the conventional structures, an object of the present invention is to provide a liquid container in which even if a knocking body is knocked inadvertently, the liquid in the container is prevented from being discharged. 
     To attain the aforementioned and other objects, in an exemplary, non-limiting embodiment, a knock-type liquid container according to the present invention includes a body having a tank that holds a liquid therein and an outlet provided at a forward end, a piston in the tank, and a piston-advancing mechanism having a knocking body that projects rearwardly of the body for advancing the piston in the tank forwardly when the knocking body is knocked in an axial direction of the liquid container. A rear end of the liquid container, except for the knocking body, has a surface making an angle other than a right angle with the axial direction. 
     Hence, when the knocking body is inadvertently knocked by surroundings and the rear end of the knocking body is moved toward the liquid container (except the knocking body) until the rear end of the knocking body is flush with the rearmost portion of the rear end of the liquid container (except the knocking body), the knocking body is unable to move any further into the liquid container. Hence, the knocking body is prevented from being knocked at a most completely forward position in the axial direction. This prevents the piston from being advanced forwardly, thereby preventing unwanted discharge of the liquid through the liquid outlet of the body. When the user attempts to push the piston to discharge the liquid, he can discharge the liquid by knocking the knocking body into the container further than the rearmost portion of the rear end of the liquid container (except the knocking body). 
     When the knocking body is at a non-knocking position, a distance in the axial direction between a rear end surface of the knocking body and a rearmost portion of the rear end of the liquid container (except the knocking body) can be selected to be equal to or less than a stroke of the knocking body required for advancing the piston. Thereby, the rear end of the knocking body is knocked into the liquid container until the rear end of the knocking body is flush with the rearmost portion of the rear end of the liquid container (except the knocking body), and the piston is unable to advance any further. Thus, the liquid can be prevented from being discharged forwardly of the liquid outlet. 
     The piston-advancing mechanism can include a piston rod having a front end coupled to the piston, extending rearwardly of the piston, having a male thread on an outer circumferential surface thereof and prevented from rotating with respect to the tank, a piston rod guide having a female-threaded hole on a front inner circumferential surface, the female-thread hole receiving the male-threaded piston rod screwed thereinto, an inner sleeve into which the piston rod is unrotatably inserted, a rotating cam unrotatably mounted around an outer circumferential surface of the piston rod guide, the knocking body, a rear cap that includes a rotating cam mechanism together with the rotating cam and the knocking body, and a return spring that urges the rotating cam rearwardly. 
     The rotating cam mechanism converts an amount of knock of the knocking body into an amount of rotation of the rotating cam. Hence, when the knocking body is knocked, the rotating cam mechanism converts knocking of the knocking body into rotation of the rotating cam, so that the piston rod guide rotates. Because the male-threaded piston rod that is screwed into the female-threaded hole of piston rod guide cannot rotate relative to the tank, the piston rod advances so that the piston is pushed forwardly. The rotating cam mechanism allows for some “play” (e.g., delay) from the knocking of the knocking body until the rotating cam actually rotates, so that an inadvertent knocking does not cause the piston to advance forwardly by utilizing the play. 
     The piston-advancing mechanism can include a piston rod having a front end coupled to the piston, extending rearwardly of the piston, having a male thread on an outer circumferential surface thereof and prevented from rotating with respect to the tank, a rotating cam having a female threaded hole receiving the male thread of the piston rod screwed thereinto, a ratchet sleeve through which a piston rod extends, the ratchet sleeve being fixed forwardly of the rotating cam in the tank, a knocking cam that is positioned rearward of the rotating cam and can rotate the rotating cam, the knocking body, and a knock spring that is disposed between the knocking cam and the knocking body and resiliently urges the knocking body rearwardly. 
     One of the knocking body and the knocking cam has a projection formed thereon and the other of the knocking body and the knocking cam has a beveled path that inclines in the axial direction and fittingly receives the projection. The rotating cam has a front end with saw-teeth formed thereon and the ratchet sleeve is formed with a ratchet tooth that can mesh with the saw-teeth formed on the rotating cam and is movable to extend and retract in the axis direction. When the knocking body is knocked, the projection formed on one of the knocking body and the knocking cam moves in the beveled path formed on the other of the knocking body and the knocking cam, so that the knocking cam rotates and therefore the rotating cam rotates. 
     Because the male-threaded piston rod that is screwed into the female-threaded hole of the rotating cam cannot rotate relative to the tank, the piston rod advances so that the piston is pushed forwardly. There is some play before the saw-teeth of the rotating cam overrides the ratchet tooth of the ratchet sleeve. This play is utilized to prevent the piston from advancing forwardly when the knocking body is inadvertently knocked. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other purposes, aspects and advantages of the present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limiting the present invention, and wherein: 
     FIG. 1 is a longitudinal side view illustrating a liquid container  10  of a first embodiment of a liquid container according to the invention; 
     FIG.  2 ( a ) is a top view illustrating a rear cap  28  of FIG. 1; 
     FIG.  2 ( b ) is a front view illustrating the rear cap  28  of FIG. 1; 
     FIG.  2 ( c ) is a longitudinal cross-sectional view illustrating the rear cap  28  of FIG. 1; 
     FIG.  2 ( d ) is a front view illustrating the state where a knocking body  32  is not knocked; 
     FIG.  2 ( e ) is a front view illustrating the state where the knocking body  32  is knocked to supply liquid; 
     FIG.  3 ( a ) is a top view of the knocking body  32  of FIG. 1; 
     FIG.  3 ( b ) is a longitudinal cross-sectional view of the knocking body  32  of FIG. 1; 
     FIG.  4 ( a ) is a top view of a rotating cam  30  of FIG. 1; 
     FIG.  4 ( b ) is a longitudinal cross-sectional view of the rotating cam  30  of FIG. 1; 
     FIG.  4 ( c ) is a view seen in a direction shown by an arrow  4 ( c ) of FIG.  4 ( b ); 
     FIGS.  5 ( a ) to  5 ( c ) are illustrative diagrams of development views illustrating the operation of a rotating cam mechanism; 
     FIG. 6 is a longitudinal cross-sectional view of a piston rod guide  26  of FIG. 1; 
     FIG.  7 ( a ) is a top view of an inner sleeve  27  of FIG. 1; 
     FIG.  7 ( b ) is a longitudinal cross-sectional view of the inner sleeve  27  of FIG.  1 ; 
     FIG. 8 is a transverse cross-sectional view taken along line  8 — 8  of FIG. 1; 
     FIG. 9 is a rear longitudinal cross-sectional view of a liquid container  40  according to a second embodiment of the invention; 
     FIG. 10 is an exploded perspective view of a piston-advancing mechanism  43  of FIG. 9; 
     FIGS.  11 ( a )- 11 ( b ) are illustrative diagrams of a side view illustrating the operation of the rotating cam  46  and a ratchet sleeve  47  of FIG. 9; and 
     FIGS.  12 ( a )- 12 ( e ) illustrate an example of a modification of the rear cap of FIG. 2, with 
     FIG.  12 ( a ) being a top view, 
     FIG.  12 ( b ) being a front view, 
     FIG.  12 ( c ) being a longitudinal cross-sectional view, 
     FIG.  12 ( d ) being a front view of the rear end portion of the rear cap  54 , and 
     FIG.  12 ( e ) being a front view when the knocking body is knocked to the liquid. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the invention will be described with reference to the accompanying drawings. In this specification, the terms “forward” and “forwardly” are used to cover the orientation toward the ink outlet of the liquid container and the terms “rearward” and “rearwardly” are used to cover the orientation toward the knocking body of the liquid container. 
     First Embodiment 
     FIGS. 1-8 illustrate a first embodiment of the present invention. 
     Referring to these drawings, a liquid container  10  generally includes a body  12  having a tank T which holds a liquid L such as correcting liquid, writing ink, and cosmetic liquid and having a liquid outlet  12   b  provided at a front end thereof, a front end unit  13  that is mounted to a forward end portion of the body  12 , a piston  22  slidable in the tank T, and a piston-advancing mechanism  23  for advancing the piston  22  forwardly. The piston-advancing mechanism  23  is provided at a rearward portion of the liquid container  10 . 
     The front end unit  13  includes a tapered sleeve  14  into which a forward end portion of the body  12  is press-fitted, a pipe holder  16  that is press-fitted into a rearward portion of the tapered sleeve  14 , a forward end pipe  18  having a rear end portion securely fitted into the pipe holder  16 , and a brush (i.e., a liquid-applier member)  20  having a base portion into which a front end portion of the forward end pipe  18  extends such that the base portion is sandwiched between the forward end pipe  18  and the tapered sleeve  14 . When the liquid container is not in use, a cap  36  is detachably fitted over the forward end of the body  12  to protect the brush  20 . When the liquid container  10  is shipped, a cover  38  is fitted over the tapered sleeve  14  to protect a tip of the brush  20 . 
     The piston-advancing mechanism  23  includes a piston rod  24 , a piston rod guide  26 , an inner sleeve  27 , a rear cap  28 , a rotating cam  30 , a knocking body  32 , and a return spring  34 . The piston rod  24  has a forward end portion coupled to the piston  22  and extends rearwardly from the piston  22 , and has a male thread  24   a  provided on an outer circumferential surface. The piston rod guide  26  has a female-threaded hole  26   a  receiving the male thread  24   a  of the piston rod  24  screwed thereinto. The inner sleeve  27  receives a tip portion of the piston rod guide  26  and the piston rod  24  therein. The tip portion of the piston rod guide  26  is rotatably supported in the sleeve  27  while the piston rod  24  is unrotatably inserted into the inner sleeve  27 . The rear cap  28  is connected to the inner sleeve  27 . The piston rod guide  26  extends through the rotating cam  30  such that the rotating cam  30  is unrotatably mounted around the piston rod  26 . The knocking body  32  projects rearwardly from the rear cap  28 . The return spring  34  urges the rotating cam  30  rearwardly of the liquid container  10 . 
     The piston-advancing mechanism  23  will be described in more detail hereinbelow. 
     The rear cap  28 , knocking body  32 , and rotating cam  30  form a rotating cam mechanism. As shown in FIG.  2 ( c ), the rear cap  28  has a plurality of cam projections  28   a  that are formed in an inner circumferential surface of the rear cap  28  at circumferential intervals. 
     Each of the cam projections  28   a  has a beveled cam surface formed at a front end portion thereof. The beveled cam surface inclines relative to the axial direction of the container  10 . The rear ends of the cam projections  28   a  are continuous with an inwardly extending annular projection  28   c . Cam grooves  28   b  formed between adjacent cam projections  28   a  slidably receive projections  32   a  (e.g., see FIG. 3) formed on an outer circumferential surface of the knocking body  32 . 
     As shown in FIG. 3, the knocking body  32  has a saw-tooth shaped cam surface  32   b  in its tip. The cam grooves  28   b  of the rear cap  28  also slidably receive projections  30   a  (e.g., see FIG. 4) formed on an outer circumferential surface of the rotating cam  30 . 
     As shown in FIGS.  4 ( a )- 4 ( b ), each of the projections  30   a  of the rotating cam  30  has a beveled cam surface  30   b  formed at a rear end of the projection  30   a  and inclining relative to the axial direction of the container  10 . When the knocking body  32  is forwardly knocked, the cam surface  32   b  of the knocking body  32  causes the rotating cam  30  to advance forwardly against the urging force of the return spring  34 , so that the projections  30   a  of the rotating cam  30  are pushed forwardly of the cam grooves  28   b  of the rear cap  28 . When the knocking force of the knocking body  32  is released subsequently, the urging force of the return spring  34  causes the cam surfaces  30   b  of the projections  30   a  of the rotating cam  30  to slide over the cam surfaces  32   b  of the knocking body  32  and the cam surfaces of cam projections  28   a  of the rear cap  28  toward adjacent cam grooves  28   b  so that the projections  30   a  fit into the cam grooves  28   b  (FIG.  5 ). Thus, every time the knocking body  32  performs one knocking operation, the rotating cam  30  rotates by an amount that the projections  30   a  of the rotating cam  30  move to adjacent cam grooves  28   b.    
     As shown in FIG.  4 ( c ), a plurality of axial grooves  30   c  are formed in an inner circumferential surface of the rotating cam  30 . The axial grooves  30   c  fittingly receive axial ribs  26   b  (FIG. 6) of the piston rod guide  26  so that the rotating cam  30  and the piston rod guide  26  can rotate together. 
     As shown in FIG. 6, a forward end portion of the piston rod guide  26  is formed with an annular projection  26   c  having a larger outer diameter than the rest of the piston rod guide  26 . 
     As shown in FIG. 7, the inner sleeve  27  has a pair of windows  27   a  formed on the outer circumferential surface thereof. The inner sleeve  27  has a tapered inner circumferential surface near the windows  27   a , the tapered inner circumferential surface increasing in diameter toward the rear end. The tapered inner circumferential surface has projections  27   b  formed at locations closer to the rear end than the windows  27   a , the projections  27   b  being at the same circumferential position as the window  27   a . The shortest distance between the forward ends of the opposing projections  27   b  is the same as the diameter of the inner sleeve  27  at the forward ends of the window  27   a . The annular projections  26   c  of the piston rod guide  26  engage the projections  27   b  of the inner sleeve  27  so that the piston rod guide  26  is rotatable relative to the inner sleeve  27  but is not pulled out rearwardly from the inner sleeve  27 , and consequently the axial direction position of the piston rod guide  26  is fixed. 
     The inner sleeve  27  has a plurality of axial grooves  27   c  formed on the inner circumferential surface at a location more rearward than the projections  27   b . The axial grooves  27   c  fittingly receive axial ribs  28   d  formed in the forward end portion of the outer circumferential surface of the rear cap  28  of FIG. 2 while at the same time projections  27   d  formed on the bottoms of the axial grooves  27   c  fit into small holes  28   e  formed in the axial ribs  28   d , so that the inner sleeve  27  and rear cap  28  are integrally coupled together. 
     As shown in FIG. 8, the piston rod  24  has a non-circular cross section. For example, in the present embodiment, the piston rod  24  is in the shape of a deformed cylinder that has been partially cut away in two planes parallel to the longitudinal axis of the piston rod  24 . 
     The inner sleeve  27  has a small-diameter inner sleeve portion  27   e  that has a bore  27   f  which the piston rod  24  penetrates. The bore  27   f  has the same cross section as that of the piston rod  24 . As the piston rod  24  penetrates the bore  27   f , the piston rod  24  is unrotatable relative to the inner sleeve  27 . The outer surface of the inner sleeve  27  has a knurled outer surface  27   g  in a part thereof, the knurled outer surface  27   g  fitting to ribs formed in a part of the inner circumferential surface of the body  12 . A knurled fitting structure forms a rotation-preventing construction that prevents the inner sleeve  27  from relatively rotating with respect to the body  12 . Of course, the knurled fitting construction may be replaced by another fitting construction such as a rib-fitting structure, polygon-fitting structure, and a key-and-key groove fitting structure or the like, each of which can prevent relative rotation of the body  12  and inner sleeve  27 . 
     As described above, the inner sleeve  27  is prevented from rotating with respect to the piston rod  24 . Thus, the piston rod  24  cannot rotate with respect to the body  12 . A tapered surface  27   h  is formed adjacent to the knurled outer surface  27   g  and is smaller in diameter nearer the forward end of the liquid container. The tapered surface  27   h  abuts a tapered surface  12   a  formed on the inner surface of the body  12  that is smaller in diameter nearer the forward end of the liquid container. The rear cap  28  is press-fitted into the body  12  to be securely fixed to the body  12 . The inner sleeve  27  is fixed in the body  12  such that the inner sleeve  27  is sandwiched between the tapered surface  12   a  of the body  12  and the rear cap  28 . 
     As shown in FIGS.  2 ( a )- 2 ( e ), the rear end surface of the rear cap  28 , which forms a rear end surface of the liquid container  10  (except for the knocking body  32 ), is a beveled end surface  28   g  which is not normal to the axial direction, but is at an angle with the axis of the liquid container  10 . An axial distance D 1  (e.g., see FIG. 1) between the rearmost portion of the beveled end surface  28   g  and a rear end surface of the knocking body  32  when the knocking body  32  is at a non-knocking position is equal to or shorter than a stroke of the knocking body  32  required for advancing the piston  22 , as described below. 
     The piston-advancing mechanism  23  can be assembled into an integral subassembly separate from the body  12 . The integral sub-assembly can be assembled into the body  12  by press-fitting the rear cap  28  of the integral sub-assembly into the body  12  from the rear end. The front end unit  13  can also be assembled as an integral sub-assembly separate from the body  12 . After the piston-advancing mechanism  23  is assembled into the body  12 , the liquid L is introduced into the body  12  through a forward inlet of the body  12 , and finally the front end unit  13  is press-fitted into the body  12 , thereby completing the assembly of the liquid container  10 . 
     When the user attempts to discharge from the liquid container  10 , the cap  36  and cover  38  are removed from the liquid container  10  and then the liquid L is applied to, for example, paper by using the brush  20 . If the user wishes to supply more of the liquid through the brush  20 , the user operates the knocking body  32  to perform the knocking operation with respect to the body  12 . 
     As described above, every time the knocking body  32  is knocked one time, the rotating cam  30  rotates by an angle by which the projections  30   a  of the rotating cam  30  move circumferentially to adjacent cam grooves  28   b  so that the piston rod guide  26  rotates together with the rotating cam  30 . The piston rod  24  does not rotate with respect to the body  12 , and therefore the piston rod guide  26  rotates with respect to the piston rod  24  so that the piston rod  24  and piston  22  advance through threaded-engagement between the male thread  24   a  of the piston rod  24  and the female-threaded hole  26   a  of the piston rod guide  26 . The advancement of the piston  22  in the tank T pushes the liquid L in the tank T toward the liquid outlet  12   b  provided at the forward end of the body  12 , then the liquid passes through the pipe  18 , and is finally discharged from the tip of the brush  20 . 
     When the liquid container  10  is carried in, for example, a handbag or the like, if the knocking body  32  is pushed accidentally by something else in the handbag, the knocking body  32  may be easily pushed and knocked until the rear end surface of the knocking body  32  is flush with the rearmost portion of the beveled end surface  28   g  of the rear cap  28 . However, the distance D 1  (e.g., see FIGS.  1  and  2 ( b )) between the rearmost portion of the beveled end surface  28   g  of the rear cap  28  and the rear end surface of the knocking body  32  when the knocking body  32  is at a non-knocking position is shorter than a stroke of the knocking body  32  required for advancing the piston  22 . 
     Thus, even if the knocking body  32  is knocked until the rearmost portion of the beveled end surface  28   g  is flush with the rear end surface of the knocking body  32 , the piston  22  is not advanced yet. The stroke D 0  of the knocking body  32  required for advancing the piston  22  is a distance over which the knocking body  32  moves to cause the projections  30   a  of the rotating cam  30  to advance forwardly from the cam grooves  28   b  of the rear cap  28 . 
     As described above, after the projections  30   a  of the rotating cam  30  have been pushed forwardly from the cam grooves  28   b , and the knocking force of the knocking body  32  is released, the projections  30   a  move to adjacent cam grooves  28   b  along the cam surface  32   b  of the knocking body  32  and the cam surface of the cam projections  28   a  of the rear cap  28 , so that the rotating cam  30  can rotate. However, if the stroke of the knocking body  32  is not enough for the projections  30   a  of the rotating cam  30  to advance forwardly from the cam grooves  28   b , a decrease in knocking force of the knocking body  32  causes the projections  30   a  to retract into the same cam grooves  28   b  so that the rotating cam  30  does not rotate. 
     As a result, the rotating cam  30  moves only back and forth somewhat and the piston rod guide  26  does not rotate, preventing the piston  22  from advancing. If the knocking body  32  bumps some object and is pushed by the object, the knocking body  32  enters a so-called “half knock condition (D 1  of FIGS.  1  and  2 ( d )),” (i.e., the rear end of the knocking body  32  becomes flush with the rearmost position of the beveled end surface  28   g ). In this manner, the piston  22  is prevented from pushing the liquid out of the liquid container  10 . When the user operates intentionally the knocking body  32  so that the rear end of the knocking body  32  advances forwardly further than the rearmost portion of the beveled surface  28   g  of the rear cap  28  (D 0  of FIGS.  1  and  2 ( e )), the piston  22  advances to discharge the liquid. 
     FIG. 12 illustrates another beveled end surface  28 ′g of the rear cap  28 ′ that is a modification of the beveled end surface  28   g  of the rear cap  28 . The opposing two points of the beveled end surface  28 ′g are rearmost points of the rear cap  28 ′. 
     Second Embodiment 
     FIGS. 9-11 illustrate a second embodiment of the invention. Referring to FIGS. 9-11, a liquid container  40  generally includes the body  12 , the front end unit  13 , the piston  22  slidable in the tank T, and a piston-advancing mechanism  43  provided at a rear portion of the liquid container  40  for advancing the piston  22  forwardly. As the front end unit  13  is of the same construction as the first embodiment, the description and drawings are omitted. 
     The piston-advancing mechanism  43  includes a piston rod  24 , a rotating cam  46 , a ratchet sleeve  47 , a knocking cam  48 , a rear cap  54  fixed at an end of the tank T, a knocking body  50  that protrudes rearwardly of the rear cap  54 , and a knocking spring  52 . The piston rod  24  is coupled integrally with the piston  22  and extends rearwardly. The piston rod  24  has a male thread  24   a  on its outer circumferential surface. The rotating cam  46  is formed with a female thread hole  46   c  therein into which the male thread  24   a  of the piston rod  24  is screwed. The ratchet sleeve  47 , through which the piston rod  24  extends, is fixed in the tank T at a location forward of the rotating cam  46 . The knocking cam  48  is at a location rearward of the rotating cam  46  and can rotate the rotating cam  46 . The knocking spring  52  is mounted between the knocking cam  48  and knocking body  50  and resiliently urges the knocking body  50  rearwardly. 
     The piston-advancing mechanism  43  will now be described in more detail hereinbelow. 
     The rear cap  54  has a pair of window holes  54   a  formed on an outer circumferential surface thereof. The window holes  54   a  receive resilient projections  50   b  formed on the tip of resilient straps  50   a  formed on the circumferential surface of the knocking body  50 . The resilient projections  50   b  slide in the windows  54   a  so that the knocking body  50  is movable axially and not rotatable with respect to the rear cap  54 . 
     The knocking body  50  has a beveled groove  50   c  formed in a side surface thereof, the beveled groove  50   c  being at an angle with regard to an axis of the liquid container  40 . The beveled groove  50   c  receives a projection  48   a  formed on the outer side surface of the knocking cam  48  so that the projection  48   a  is movable along the beveled groove  50   c.    
     The knocking cam  48  has saw-teeth  48   b  formed in a forward end thereof. The saw-teeth  48   b  can mesh with saw-teeth  46   a  formed in a rear end of the rotating cam  46 . Further, the rotating cam  46  has saw-teeth  46   b  formed at a front end thereof, an inclined surface of the saw-teeth  46   b  are in an opposite direction to an inclined surface of the saw-teeth  46   a  formed at the rear end of the rotating cam  46 . The saw-teeth  46   b  can mesh with a ratchet tooth  47   a  formed at a rear end of the ratchet sleeve  47 , and the ratchet tooth  47   a  is resiliently deformable by an L-shaped slit  47   d  so that the ratchet tooth  47   a  can protrude or retract in the axial direction. 
     The ratchet sleeve  47  has an elongated insertion bore  47   b  of which a cross section is the same shape as the cross section of the piston rod  24 , so that the piston rod  24  unrotatably extends through the insertion bore  47   b . The ratchet sleeve  47  has a plurality of axial ribs  47   c  formed on an outer circumferential surface thereof. The axial ribs  47   c  fit axial grooves  54   b  formed on an inner circumferential surface of the rear cap  54  so that the ratchet sleeve  47  is unrotatable with respect to the rear cap  54 . Stepped surface  47   f  facing a forward end of the ratchet sleeve  47  abuts a stepped surface  54   c  facing a rear end of the rear cap  54 . 
     Thus, the ratchet sleeve  47  is fixed with respect to the rear cap  54 . Because the rear cap  54  is press-fitted into the body  12 , the ratchet sleeve  47  is fixed relative to the body  12 . As described above, the ratchet sleeve  47  is prevented from rotating with respect to the piston rod  24 , and thus, the piston rod  24  cannot rotate relative to the body  12 . 
     The rear end surface of the rear cap  54  that forms a rear end surface of the liquid container  40  (except for the knocking body  50 ) is not normal to the axis of the liquid container  40 , but is a beveled surface  54   d  cut at an angle with the axis of the container  40 . The distance D 2  (see FIG. 9) between a rearmost portion of the beveled surface  54   d  and a rear end surface of the knocking body  50  is equal to or somewhat shorter than the stroke of the knocking body  50  required for advancing the piston  22 . 
     Similarly to the first embodiment, the piston-advancing mechanism  43  can be integrally assembled into an integral sub-assembly separate from the body  12 . The integral sub-assembly can be assembled into the body  12  by press-fitting the rear cap  54  of the integral sub-assembly into the body  12  from the rear end. After the piston-advancing mechanism  43  is assembled to the body  12 , then the liquid L is introduced through the forward opening of the body  12 , and finally the front end unit  13  is press-fitted into the body  12 , thereby completing the assembly of the liquid container  40 . 
     When the liquid L is discharged from the liquid container  40  of the above described construction, the brush  20  is used to apply the liquid L to an object. If more of the liquid L should be discharged through the brush  20 , the user performs a knocking operation of the knocking body  50 . 
     When the knocking body  50  is advanced by the knocking operation, the knocking cam  48  cannot advance, but the projection  48   a  of the knocking cam  48  moves along the beveled groove  50   c  of the knocking body  50 , so that the knocking cam  48  rotates in a direction shown by an arrow of FIG.  10 . Because the saw-teeth  48   b  of the knocking cam  48  mesh with the saw-teeth  46   a  of the rotating cam  46 , the rotation of the knocking cam  48  causes the rotating cam  46  to rotate in the same direction. At this moment, the saw-teeth  46   b  of the rotating cam  46  rotate with sliding on the beveled surface of the ratchet tooth  47   a  formed in the ratchet sleeve  47  and also causing the ratchet tooth  47   a  to extend and retract. 
     Because the ratchet sleeve  47  prevents the piston rod  24  from rotating, when the rotating cam  46  rotates in the direction of the arrow, the piston rod  24  threadably engaged with the rotating cam  46  advances to push the piston  22 . The piston  22  pushes the liquid L in the body  12 , so that the liquid L passes through the pipe  18  and is discharged through the brush  20 . 
     It is noted that, in the second embodiment, the knocking body  50  may be inadvertently knocked. That is, when the liquid should not be discharged, if some object bumps the knocking body  50 , then the knocking body  50  may be moved at least over the distance D 2  without difficulty. However, because the distance D 2  is substantially the same as or somewhat shorter than the stroke over which the knocking body  50  should move to cause the piston  22  to advance, even if the knocking body  50  is knocked until the rear end of the knocking body  50  becomes flush with the rearmost portion of the beveled surface  54   d  of the rear cap  54 , the piston  22  is not pushed forwardly yet. 
     In other words, when the knocking cam  48  moves in the circumferential direction at least a minimum distance D 3  as shown in FIG.  11 ( a ), required for one of the saw-teeth  46   b  of the rotating cam  46  to push the ratchet tooth  47   a  out of the way to pass the ratchet tooth  47   a , the rotating cam  46  rotates positively to ensure that the piston rod  24  and the piston  22  are advanced. Thus, the stroke of the knocking body  50  required for the rotating cam  46  and knocking cam  48  to move the circumferential distance D 3  is equal to the stroke of the knocking body  50  required for the piston  22  to advance. 
     On the other hand, as shown in FIG.  11 ( b ), when the knocking cam  48  moves over a circumferential distance D 4  (&lt;D 3 ) which is not long enough for one of the saw teeth  46   b  to push the ratchet tooth  47   a  out of the way to pass the ratchet tooth  47   a  of the ratchet sleeve  47 , if the knocking operation of the knocking body  50  is released, then the rotating cam  46  and knocking cam  48  rotate in the opposite directions to return to their original positions. 
     Accordingly, the piston rod  24  and piston  22  advance part way, but return as the rotating cam  46  returns to its original position. Therefore, the liquid L in the tank T is once discharged from the tank T, but is sucked back into the tank T, so that the liquid is prevented from being discharged. When the user attempts to discharge the liquid from the liquid container, the user knocks the rear end of the knocking body  50  deeper than the rearmost portion of the beveled surface  54   d  of the rear cap  54  so that the piston  22  can advance to normally discharge the liquid from the liquid container  40 . 
     As described above, in each of the embodiments, the force required for normal knocking can be set less than a maximum of 9.8 N (=1 kg weight), for example, within a range of about 2.9-4.9 N (=300 to 500 g weight) that can be applied normally, and yet can prevent unwanted discharge of liquid due to an inadvertent knocking operation. 
     In the present invention, a component described as a single component may be replaced with an integral assembly of a plurality of components. Also, an integral assembly described as a plurality of components may be replaced with a single component. 
     Hence, as described above, according to the present invention, an inadvertent knocking operation does not allow the piston to advance sufficiently, thereby preventing unwanted discharge of liquid from the container without having to increase the force required for knocking of the knocking body. Thus, the normal knocking operation can be performed comfortably with a force that the user can normally apply. 
     With the invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art intended to be included within the scope of the following claims.