Patent Publication Number: US-8123505-B2

Title: Reciprocating pump with sealing collar arrangement

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a reciprocating pump. 
     2. Related Background Art 
     A reciprocating pump in which a reciprocating member reciprocates, so as to perform a pumping action, thereby sucking/discharging a liquid into/from a manifold has conventionally been known. This reciprocating pump is a pump in which the reciprocating member reciprocates, so that the liquid is sucked from the outside when a pump chamber formed within the manifold is depressurized, whereas the liquid is discharged to the outside when the pump chamber is pressurized. Since the pumping action is thus realized by pressure changes in the pump chamber, the pump chamber is liquid-tightly sealed with a seal packing or O-ring (see, for example, Patent Document 1).
     [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-162646   

     SUMMARY OF THE INVENTION 
     However, the conventional reciprocating pump has been problematic in that the manifold is corroded by the liquid for use, so that defects occur in sealing, whereby the liquid leaks from the pump chamber, and pressure oscillation increases because of the leakage, thus lowering performances of the reciprocating pump. 
     For solving such a technical problem, it is an object of the present invention to provide a reciprocating pump kept from lowering its performances. 
     The present invention provides a reciprocating pump ( 1 ) comprising a sealing member ( 10  or  22  or  23 ) for liquid-tightly sealing the inside of a manifold ( 3 ), wherein a reciprocating member ( 2 ) performs a pumping action for sucking a liquid for use into the manifold ( 3 ) and discharging the liquid therefrom by reciprocating; a collar ( 14  or  20  or  21 ) made of a material having a higher resistance to corrosion than the manifold ( 3 ) is liquid-tightly attached to an inner face of the manifold ( 3 ); and the sealing member ( 10  or  22  or  23 ) is liquid-tightly in contact with the collar ( 14  or  20  or  21 ). 
     The present invention provides a reciprocating pump ( 1 ) comprising: a manifold ( 3 ) having a pump chamber ( 4 ) and a channel ( 80 ) that connects the pump chamber ( 4 ) and the exterior; a plunger ( 2 ), mounted in the pump chamber ( 4 ), that reciprocates therein for sucking a liquid into the manifold ( 3 ) and discharging the liquid therefrom through the channel ( 80 ); a collar ( 14 ), made of a material having a higher resistance to corrosion than the manifold ( 3 ), that is liquid-tight and provided on a part of the side wall of the pump chamber ( 4 ); and a sealing member ( 10 ), provided between the collar ( 14 ) and the plunger ( 2 ), for providing a liquid-tight seal. 
     The present invention provides a reciprocating pump ( 1 ) comprising: a manifold ( 3 ) having a pump chamber ( 4 ) and a channel ( 80 ) that connects the pump chamber ( 4 ) and the exterior; a plunger ( 2 ), mounted in the pump chamber ( 4 ), that reciprocates therein for sucking a liquid into the manifold ( 3 ) and discharging the liquid therefrom through the channel ( 80 ); a valve member ( 90  or  91 ) provided in the channel ( 80 ); a collar ( 20  or  21 ), made of a material having a higher resistance to corrosion than the manifold ( 3 ), that is liquid-tight and provided on a part of the inner face of the channel ( 80 ); and a sealing member ( 22  or  23 ), provided between the collar ( 20  or  21 ) and the valve member ( 90  or  91 ), for providing a liquid-tight seal. 
     Thus, a collar made of a material more excellent in resistance to corrosion than a manifold is interposed between a part of the manifold in contact with a sealing member and the sealing member. This can prevent the part in contact with the sealing member from being corroded by the liquid for use, so that the sealing function is fully exhibited, whereby the leakage from the pump chamber can be prevented from occurring and increasing the pressure oscillation is prevented, thus keeping the reciprocating pump from lowering its performances. Since the collar made of a material excellent in resistance to corrosion is used only in the part in contact with the sealing member, it is not necessary for the manifold as a whole to be made of a material excellent in resistance to corrosion, which is economically advantageous. 
     Here, it will be preferred if the collar ( 14  or  20  or  21 ) is constituted by a material having a higher resistance to wear than the manifold ( 3 ). Such a structure can also prevent the part in contact with the sealing part from wearing, so that the sealing function can be exhibited more fully, thus further keeping the reciprocating pump from lowering its performances. 
     Preferably, the collar ( 14  or  20  or  21 ) has a chamfer ( 14   b  or  20   b  or  21   b ) and a groove ( 14   a  or  20   a  or  21   a ) in an outer peripheral part thereof, whereas an adhesive reservoir ( 60 ) is provided between the chamfer ( 14   b  or  20   b  or  21   b ) and the manifold ( 3 ) and also between the groove ( 14   a  or  20   a  or  21   a ) and the manifold ( 3 ). Such a structure allows an adhesive to fill the chamfer and groove, thereby yielding the adhesive reservoir, which can enhance the bonding strength and prevent the leakage from occurring. 
     Preferably, the distance (D 1 ) between the chamfer ( 14   b  or  20   b  or  21   b ) of the collar ( 14  or  20  or  21 ) and a part ( 14   c ) of the collar ( 14  or  20  or  21 ) contacted to the liquid is shorter than the distance (D 2 ) between the groove ( 14   a  or  20   a  or  21   a ) of the collar ( 14  or  20  or  21 ) and the part ( 14   c ). 
     Preferably, the sealing member ( 10 ) includes a spring ( 15 ), adapted to push a lip part ( 70 ) of the sealing member ( 10 ) inward. 
     Preferably, the collar ( 14 ) covers the lip part ( 70 ) of the sealing member ( 10 ). 
     Preferably, the collar ( 14  or  20  or  21 ) is press-fit into the manifold ( 3 ). Such a structure makes it possible to join the collar and manifold to each other without clearances, thereby preventing the leakage from occurring. 
     It will be preferred from economical viewpoints if the material for the collar ( 14  or  20  or  21 ) is stainless steel which is excellent in resistance to corrosion as compared with titanium or the like, for example. Stainless also inhibits wear, thereby further preventing the leakage from occurring and the pressure oscillation from being increased by the leakage. 
     The present invention can prevent the leakage from occurring and increasing the pressure oscillation, while keeping the cost from rising, whereby the reciprocating pump can be kept from lowering its performances. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  A sectional view showing the reciprocating pump in accordance with an embodiment of the present invention. 
         FIG. 2  A sectional view showing a collar in contact with an O-ring in  FIG. 1 . 
         FIG. 3  A sectional view showing a collar in contact with a high-pressure seal in  FIG. 1 . 
         FIG. 4  A sectional view showing the high-pressure seal and collar in  FIG. 1  under magnification. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following, an embodiment of the present invention will be explained with reference to the accompanying drawings. In the explanation of the drawings, the same constituents will be referred to with the same numerals without repeating their overlapping descriptions. Ratios of dimensions in the drawings do not always match those in the explanation. 
       FIG. 1  is a sectional view showing the reciprocating pump in accordance with the embodiment of the present invention.  FIG. 2  is a sectional view showing a collar in contact with an O-ring in  FIG. 1 .  FIG. 3  is a sectional view showing a collar in contact with a high-pressure seal in  FIG. 1 .  FIG. 4  is a sectional view showing the high-pressure seal and collar in  FIG. 1  under magnification. In  FIG. 1 , the parts on the right and left sides of the center line of a plunger  2  illustrate cases where the plunger  2  is located at its top dead center (see the broken line A in  FIG. 1 ) and bottom dead center (see the broken line B in  FIG. 1 ), respectively. 
     As shown in  FIG. 1 , the reciprocating pump  1  is a pump in which the plunger  2  constituting a reciprocating member reciprocates (moves up and down in the drawing), so as to perform a pumping action for sucking and discharging a liquid for use, and is favorably employed when releasing the liquid for use into which a detergent, wax, and the like are mixed in a washing machine used for washing a car, for example. The reciprocating pump  1  is equipped with a manifold  3  having a cylinder part  5  within which the plunger  2  is mounted and reciprocates. A pump chamber  4  formed on the leading end side within the cylinder part  5 . The manifold  3  has a channel  80  that connects the pump chamber  4  and the exterior. Here, the manifold  3  is formed from brass. 
     The plunger  2  is connected to a driving source (not depicted) on its rear end side (the lower side in the drawing), whereas its leading end and the manifold  3  define the pump chamber  4 . Under the control of the driving source, the plunger  2  reciprocates within the cylinder part  5 , thereby pressurizing/depressurizing the pump chamber  4 . 
     In the manifold  3 , a suction port  6  and a discharge port  7  are formed in a communicating manner on one side and the other side of the pump chamber  4 , respectively, so that the liquid for use circulates through the suction port  6 , pump chamber  4 , and discharge port  7  in succession. A suction valve  8  is provided in the channel  80  between the suction port  6  and pump chamber  4 , and functions as a check valve which passes only a unidirectional flow from the suction port  6  to the pump chamber  4 . On the other hand, a discharge valve  9  is provided in the channel  80  between the discharge port  7  and pump chamber  4 , and functions as a check valve which passes only a unidirectional flow from the pump chamber  4  to the discharge port  7 . The suction valve  8  and discharge valve  9  are pressed by elastic bodies  24 ,  25  with their fixed pressures, so as to be seated on a suction valve seat  26  and a discharge valve seat  27  under their urging forces, respectively, thereby closing the flow path. When the pressure within the pump chamber  4  changes, the valves  8 ,  9  move against the urging forces, so as to leave the suction valve seat  26  and discharge valve seat  27 , respectively, thereby opening the flow path. The suction valve seat  26  and discharge valve seat  27  are held by the manifold  3 . 
     The outer peripheral faces of the valve seats  26 ,  27  are provided with annular grooves  28 ,  29 , to which O-rings (sealing members)  22 ,  23  are mounted, respectively. The O-rings  22 ,  23  are annular bodies formed from synthetic rubber, for example. Sealing contacts of the O-rings  22 ,  23  with the manifold  3  side will be explained later. 
     In the cylinder part  5 , on the other hand, a high-pressure seal (sealing member)  10  and low-pressure seal  11  for preventing the liquid for use from leaking through the gap between the reciprocating plunger  2  and the cylinder part  5  are provided successively from the leading end side of the plunger  2  while being axially spaced from each other. The high-pressure seal  10  and low-pressure seal  11  are annular bodies provided with synthetic rubber, for example. The high-pressure seal  10  is placed in a larger-diameter part  12  formed on the pump chamber  4  side of the cylinder part  5 , whereas the low-pressure seal  11  is placed in a larger-diameter part  13  formed closer to the driving source than the larger-diameter part  12  in the cylinder part  5 . The high-pressure seal  10  is provided between the collar  14  and the plunger  2 , for providing a liquid-tight seal. The high-pressure seal  10  and low-pressure seal  11  are arranged such as to come into liquid-tightly sliding contact with the outer peripheral face of the plunger  2  when the plunger  2  reciprocates. The mounting of the high-pressure seal  10  and low-pressure seal  11  to the manifold  3  will be explained later. An annular cooling path  50  for cooling the plunger  2  is provided between the larger-diameter parts  12 ,  13 . 
     The suction port  6  is connected to the cooling path  50  through a communicating path  30 , so that a part of the liquid for use sucked from the suction port  6  is supplied through the communicating path  30 . Consequently, the plunger  2  is cooled with the liquid for use. 
     In this embodiment in particular, a collar  14  is provided between the high-pressure seal  10  and manifold  3 , whereas collars  20 ,  21  are provided between the manifold  5  and the suction valve seat  26  and discharge valve seat  27 , respectively. 
     The collar  14  on the high-pressure seal  10  side is formed from a material which is superior to the manifold  3  in terms of resistances to corrosion and wear, e.g., stainless. As shown in  FIGS. 1 and 4 , the collar  14  is formed on a part of the side wall of the pump chamber  4 . The collar  14  is an annular body, while the outer peripheral part of the collar  14  is provided with an annular groove  14   a  and a chamfer  14   b  in the end part. The fit between the collar  14  and manifold  3  is a press-fitting tolerance. Namely, the outer-diameter of collar  14  is subtlely bigger than the inner-diameter of the groove of the manifold  13  containing the collar  14 . The outer peripheral face of the collar  14  is coated with an adhesive  17 . Therefore, the collar  14  is press-fitted into the manifold  3 , so as to be liquid-tightly attached thereto. As shown in  FIG. 4 , adhesive reservoirs  60  are formed in the groove  14   a  and chamfer  14   b , so as to enhance the bonding strength, whereby the collar  14  and manifold  3  are attached to each other more liquid-tightly. The distance D 1  between the chamfer  14   b  of a collar  14  and a part  14   c  of the collar  14  contacted to the liquid is shorter than the distance D 2  between the groove  14   a  of the collar  14  and the part  14   c . Here, the liquid is located in the part  14   d  in  FIG. 4 . The above-mentioned high-pressure seal  10  is liquid-tightly in contact with the collar  14  by fitting against the inner peripheral face of the collar  14 . A core  16  is buried within the high-pressure seal  10 . When the high-pressure seal  10  is attached to the collar  14 , a spring  15  in the high-pressure seal  10  pushes a lip part  70  of the high-pressure seal  10  inward, whereby the high-pressure seal  10  comes into liquid-tightly sliding contact with the outer peripheral face of the plunger  2 . Also, as shown in  FIG. 4 , the collar  14  covers the lip part  70  of the of the high-pressure seal  10 . Also, as shown in  FIG. 1 , the low-pressure seal  11  is fixed by fitting to the manifold  3  side, whereby the low-pressure seal  11  comes into liquid-tightly sliding contact with the outer peripheral face of the plunger  2 . 
     The collars  20 ,  21  on the side of the valve seats  26 ,  27  will now be explained. Since these collars  20 ,  21  are constructed similarly to each other, only the collar  20  will be explained here with reference to  FIG. 3 . As with the collar  14 , the collar  20  is formed from a material superior to the manifold  3  in terms of resistances to corrosion and wear, e.g., stainless. The collar  20  is formed on a part of the inner face of the channel  80 . The collar  20  is an annular body, while the outer peripheral part of the collar  20  is provided with an annular groove  20   a  and a chamfer  20   b  in the end part. The fit between the collar  20  and manifold  3  is a press-fitting tolerance. Namely, the outer-diameter of collar  20  is subtlely bigger than the inner-diameter of the groove of the manifold  13  containing the collar  20 . The outer peripheral face of the collar  20  is coated with an adhesive  17 . Therefore, the collar  20  is press-fitted into the manifold  3 , so as to be liquid-tightly attached thereto. Adhesive reservoirs  60  filled with the adhesive  17  are formed in the groove  20   a  and chamfer  20   b  as in the case of the collar  14 , so as to enhance the bonding strength, whereby the collar  20  and manifold  3  are attached to each other more liquid-tightly. As shown in  FIG. 1 , the above-mentioned suction valve seat  26  and discharge valve seat  27  are inserted into the collars  20 ,  21 , whereby the O-rings  22 ,  23  are pressed against the inner peripheral faces of the collars  20 ,  21  and liquid-tightly in contact therewith. Namely, the O-rings  22 ,  23  are provided between the collars  20 ,  21  and the valve members  90 ,  91  composed of valves  8 ,  9  and the valve seats  26 ,  27 , respectively. 
     Operations and effects of the reciprocating pump  1  in accordance with this embodiment will now be explained. 
     First, the driving source (not depicted) is activated, whereby the plunger  2  reciprocates within the cylinder part  5 . When the plunger  2  moves toward the position of the bottom dead center (see the broken line B) in  FIG. 1 , the pump chamber  4  is depressurized, so that the suction valve  8  and discharge valve  9  are opened and closed, respectively, whereby the liquid for use is sucked into the pump chamber  4  through the suction valve  8  from the suction port  6 . When the plunger  2  moves toward the position of the top dead center (see the broken line A), on the other hand, the pump chamber  4  is pressurized, so that the suction valve  8  and discharge valve  9  are closed and opened, respectively, whereby the liquid for use is discharged from the pump chamber  4  to the discharge port  7  through the discharge valve  9 . These sucking and discharging steps are repeated, so that the liquid for use is unidirectionally transferred from the suction port  6  to the discharge port  7 . 
     Since the liquid for use contains the detergent and wax that corrode the manifold  3 , corrosion has conventionally occurred in the parts in contact with the seal parts, while the seal parts oscillate as the pump chamber  4  is repeatedly pressurized and depressurized, so that the oscillation causes the corrosion to progress in the oscillating direction and additionally generates wear in the manifold  3 , whereby the corrosion and wear lower the sealing function and generate leakage, while the pressure oscillation is increased by the leakage. Since the parts in contact with the high-pressure seal  10  and O-rings  22 ,  23  are the collars  14 ,  20 ,  21  excellent in resistance to corrosion in the reciprocating pump  1  in accordance with this embodiment, by contrast, the parts in contact with the high-pressure seal  10  and O-rings  22 ,  23  can be prevented from being corroded by the liquid for use, so that the sealing function is fully exhibited, thus preventing leakage from occurring in the pump chamber  4  and the pressure oscillation from being increased by the leakage, thereby keeping the reciprocating pump  1  from lowering its performances. Since the parts in contact with the high-pressure seal  10  and O-rings  22 ,  23  are the collars  14 ,  20 ,  21  excellent in resistance to wear, they are also kept from wearing and can further prevent leakage from occurring in the pump chamber  4  and the pressure oscillation from being increased by the leakage. 
     Employing the collars  14 ,  20 ,  21  makes it unnecessary to change the material of the whole manifold  3 , whereby performances can be prevented from lowering, while keeping the cost from increasing. 
     Since the collars  14 ,  20 ,  21  have the chamfers  14   b ,  20   b ,  21   b  and grooves  14   a ,  20   a ,  21   a  in their outer peripheral parts, while gaps between the manifold  3  and the chamfers and grooves are filled with the adhesive  17 , so as to form the adhesive reservoirs  60 , the bonding strength is enhanced while leakage can be prevented from occurring. 
     Since the fits between the collars  14 ,  20 ,  21  and the manifold  3  are press-fitting tolerances, the collars  14 ,  20 ,  21  can be joined to the manifold  3  without clearances, whereby leakage can be prevented from occurring. 
     Though a preferred embodiment of the present invention is specifically explained in the foregoing, the above-mentioned embodiment illustrates only an example of the reciprocating pump in accordance with the present invention, whereas the present invention is not limited to the reciprocating pump in accordance with the above-mentioned embodiment. For example, the liquid for use is not limited to those containing detergents and waxes, whereby any liquid containing a component corroding the manifold  3  is employable. 
     Though the collars  14 ,  20 ,  21  are made of stainless because of its economical superiority, they may be made of any materials, e.g., titanium, as long as they attain a higher resistance to corrosion, and preferably a higher resistance to wear, than the manifold  3 .