Abstract:
A pump includes a valve mechanism having an opened position and a closed position. The pump further includes a spring assisted mechanism for selectively moving the valve mechanism between the opened position and the closed position, and a fluid detector for detecting the level of a pumping fluid. The fluid detector is pivotally connected to the spring assisted mechanism and has a first range of pivotal travel and a second range of pivotal travel. The fluid detector further engages a spring of the spring assisted mechanism only at one portion of the first range of pivotal travel, and engages the spring of said spring assisted mechanism only at one portion of the second range of pivotal travel. The fluid detector is disengaged from the spring of the spring assisted mechanism at all other portions of the first range of pivotal travel and of the second range of pivotal travel.

Description:
BACKGROUND OF INVENTION 
     This invention relates in general to a pump, and more particularly to a steam driven pump for draining fluid from a container. 
     Pump assemblies with over-center snap-action mechanisms are useful in controlling the filling of a closed or sealed pressure vessel. For example, U.S. Pat. No. 6,099,260 to Francart, Jr. discloses a pressure vessel having a poppet type vent valve for venting the interior of the vessel to the surrounding atmosphere, a plurality of gas inlet valves subjected to high pressure inlet fluid, and a plurality of compression springs. During filling of the pressure vessel, the vent valve is in the open position and the pressure valves are closed by a float operated over-center snap-action valve actuating mechanism. As the vessel fills with fluid, the float rises and a rotatable float arm, forming part of the valve actuating mechanism, is rotated about a pivot point at one end, causing an over-center toggle linkage mechanism to move toward the center position against a spring bias. Such a mechanism has toggle linkage elements which snap quickly through the center position, closing the vent valve while simultaneously snap opening the plurality of high pressure inlet valves to pump the accumulated liquid from the vessel. Typically a compression coil spring provides such a biasing force with one end of the coil spring coupled to a fixed or stationary member of the valve mechanism or vessel. 
     While such over-center snap-action valve mechanisms operate satisfactorily to automatically control the liquid inflow and outflow from the pressure vessel, such known mechanisms are complex, difficult to maintain, and expensive. Further, the biasing force is always present as the float rises and lowers within the vessel, and the float must be sufficiently buoyant to overcome the large spring force or spring rate of the plurality of compression springs. 
     It would therefore be advantageous to provide a pump that is reliable, has a simple design, and easy to maintain and repair. It would further be advantageous to provide a pump in which the float is connected to the valve actuating mechanism and is not biased by a spring during its entire range of pivotal travel. 
     SUMMARY OF THE INVENTION 
     The above objects as well as other objects not specifically enumerated are achieved by a pump including a valve mechanism having an opened position and a closed position. The pump further includes a spring assisted mechanism for selectively moving the valve mechanism between the opened position and the closed position, and a fluid detector for detecting the level of a pumping fluid. The fluid detector is pivotally connected to the spring assisted mechanism and has a first range of pivotal travel and a second range of pivotal travel. The fluid detector further engages a spring of the spring assisted mechanism only at one portion of the first range of pivotal travel, and engages the spring of the spring assisted mechanism only at one portion of the second range of pivotal travel. The fluid detector is disengaged from the spring of the spring assisted mechanism at all other portions of the first range of pivotal travel and of the second range of pivotal travel. 
     In another embodiment of the invention, the pump includes a container and a valve block mounted to the container. The valve block has a body, a pressurized fluid inlet valve, and a pressure release valve. The valve block is further readily removable from the container. 
     In an additional embodiment of the invention, the pump includes a container and a valve block which has a valve mechanism. An actuator is connected to the valve block and mounted to travel with respect to the valve block. The actuator further selectively actuates the valve mechanism between opened and closed positions. A fluid detector for detecting the level of a pumping fluid is mechanically linked to the actuator. The actuator is arranged to travel a predetermined distance relative to the valve block before the actuator actuates the valve mechanism between the opened and the closed positions. 
    
    
     Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view, partially in cross-section, of the steam driven pump of the invention; 
     FIG. 2 is a side elevational view of the pump assembly illustrated in FIG. 1; 
     FIG. 3 is a front elevational view of the pump assembly illustrated in FIG. 2; 
     FIG. 4 is a cross-sectional view of the pump assembly taken along line  4 — 4  of FIG. 3; 
     FIG. 5 is a cross-sectional view of the pump assembly taken along line  5 — 5  of FIG. 3; 
     FIG. 6 is a cross-sectional view of the pump assembly taken along line  6 — 6  of FIG. 3; and 
     FIG. 7 is a perspective view of the toggle illustrated in FIG.  6 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings there is illustrated in FIG. 1 a steam driven pump shown generally at  10 . Typically, the steam driven pump includes a container or tank  12 . The tank  12  has a generally hollow interior  13  and includes a fluid inlet valve  14  and a fluid outlet valve  15 . The fluid inlet valve  14  and fluid outlet valve  15  may be any suitable type of fluid valve, such as, for example, a swing check valve or a piston check valve. The tank  12  further includes a mounting flange  16  disposed about a generally cylindrical opening  17 . 
     The steam driven pump  10  also typically includes a pump assembly shown generally at  18 . The pump assembly  18  is typically transversely mounted to a generally annular cap flange  20 , and extends through the opening  17  in the tank  12 . The cap flange  20  typically includes a steam inlet port  24  connected to a source of steam (not shown) and a pressurized-fluid outlet port  26  for venting the interior  13  of the tank  12  formed therein. Typically the interior  13  of the tank  12  is vented into the atmosphere. The cap flange  20  is sealingly mounted to the mounting flange  16  by any suitable means, such as, for example, threaded fasteners (not shown). Typically, an annular seal  22  is disposed between the cap flange  20  and the mounting flange  16  and provides a seal therebetween. 
     Referring now to FIGS. 2 through 4, the pump assembly  18  includes generally C-shaped frame plates  28  and a valve block  30 . The valve block  30  is generally rectangular and includes flange portions  31  extending outwardly from two opposing sides thereof. An inlet conduit  32  is formed through the valve block  30 . A portion of the inlet conduit  32  is typically threaded for receiving an externally threaded steam inlet valve assembly  33 . The steam inlet valve assembly  33  is generally cylindrical and includes a first axial passage  34 , a generally annular valve seat  35  for supporting a generally spherical valve  36 , and a flange portion  41 . The valve  36  cooperates with the valve seat  35  to close and open the steam inlet valve assembly  33 . The valve assembly  33  is commonly known as a ball check valve. The flange portion  41  is preferably hexagonally shaped for receiving a tool (not shown) for installing the valve assembly  33 . A second axial passage  38  extends through the valve assembly  33  opposite the valve seat  35 . A plurality of radially extending passages  40  are formed in the flange portion  41  of the valve assembly  33  and provide fluid communication between the axial passage  38  and the interior  13  of the tank  12 . 
     An outlet conduit  42  is formed through the valve block  30  adjacent the inlet conduit  32 . A portion of the outlet conduit  42  is typically threaded for receiving an externally threaded vent valve assembly  43 . The vent valve assembly  43  is generally cylindrical and includes an axial passage  44 , a generally annular valve seat  45 , and a flange portion  46 . The flange portion  46  is preferably hexagonally shaped for receiving a tool (not shown) for installing the valve assembly  43 . Each frame plate  28  is typically attached to opposing sides of the valve block  30 , adjacent the flanges  31 , by a plurality of suitable fasteners  48 , such as, for example, threaded fasteners. The pump assembly  18  is mounted to the cap flange  20  by any suitable means, such as, for example, threaded fasteners  49  extending through apertures (not shown) in the flange portions  31  of the valve block  30 . 
     An important aspect of the invention is that the valve block  30  is readily removable from the pump assembly  18 , and readily removable from the cap flange  20 . Readily removable is defined as the valve block  30  being capable of being disconnected from each of the frame plates  28  of the pump assembly  18  by removal of all of the plurality of fasteners  48 , and being capable of being disconnected from the cap flange  20  by removal of all of the plurality of fasteners  49 . The valve block  30  can therefore be disconnected and removed from the pump assembly  18  without the disassembly of the fame plates  28 , mechanism  50 , and linkage  118 . The readily removable feature of the valve block  30  further allows easy access the maintenance, repair, and replacement of the inlet valve assembly  33  and the vent valve assembly  43 . 
     Referring now to FIGS. 4 and 6, the pump assembly  18  further typically includes an over-center snap-action mechanism, shown generally at  50 . The mechanism  50  includes a float arm  52  having a pair of outwardly extending fingers  54  and  55 . The fingers  54  and  55  are substantially parallel and spaced apart from each other. A first pivot pin  58  passes through a first aperture  56  in the finger  54  and passes through a first aperture  57  in the finger  55  to pivotally mount the float arm  52  to the frame plates  28  about a pivot axis A. A second pin  60  passes through an aperture  61  in the float arm  52  and further extends through a first arcuate slot  62  of each frame plate  28 . 
     A pair of elongate spring arms  64  are pivotally mounted to the first pivot pin  58  about the pivot axis A. The spring arms  64  include a first aperture  66  for pivotal engagement with first pivot pin  58 , a second aperture  68 , and an arcuate slot  70 . A third pivot pin  72  passes through the second aperture  68  in each spring arm  64  to pivotally mount the spring arms  64  about a second pivot axis B. The third pivot pin  72  slidingly mounts each spring arm  64  to each frame plate  28  at a second arcuate slot  73 . 
     A helical spring  74  includes a first end having a pair of outwardly extending fingers  76  and  77 . The fingers  76  and  77  are substantially parallel and spaced apart from each other. The third pivot pin  72  passes through an aperture  78  in the finger  76  and passes through an aperture  79  in the finger  77  to pivotally mount the first end of the spring  74  to each frame plate  28  about the pivot axis B intermediate the pair of spring arms  64 . A second end of the spring  74  includes a pair of outwardly extending fingers  80  and  81 . The fingers  80  and  81  are substantially parallel and spaced apart from each other. A fourth pivot pin  86  passes through an aperture  82  in the finger  80  and passes through an aperture  83  in the finger  81  to pivotally mount the second end of the spring  74  to a toggle  90  about a third pivot axis C. The fourth pivot pin  86  passes through the arcuate slot  70  of each spring arm  64 , and further passes through a generally circular slot  88  in each frame plate  28 . 
     As illustrated in FIG. 7, the toggle  90  includes a first aperture  92 , a second aperture  94 , and an arcuate slot  96 . As shown in FIG. 6, the first pivot pin  58  passes through the first aperture  92  to pivotally mount to the toggle  90  about the first pivot axis A between the fingers  54  and  55  of the float arm  52 . A fifth pivot pin  98  passes through a second aperture  100  in the finger  54 , through a second aperture  102  in the finger  55 , and through the arcuate slot  96  of the toggle  90 . 
     Preferably, the components of the pump assembly  18  are made of stainless steel. Therefore, to reduce the reduce friction and wear associated with stainless steel to stainless steel contact, bushings are provided to reduce friction and wear between the pivot pins  58 ,  72 , and  86 , and the corresponding apertures of the frame plate  28 , float arm  52 , spring arm  64 , and spring  74 , as shown in FIG.  6 . The bushings  104  have a generally cylindrical body  105  and a generally annular flange  106 . Preferably the bushings  104  made of a material having a low coefficient of friction, such as, for example, Rulon® 641 manufactured by the Saint-Gobain Performance Plastics Company. Additionally, spacers or washers  107  may be disposed on pivot pins  58  and  72  between the bushings  104 . It will be understood that each of the pivot pins  58 ,  60 ,  72 ,  86 , and  98  may be secured to the pump assembly by any suitable means, such as, for example, retaining clips  109 . 
     The mechanism  50  also includes a fluid detector, typically a float  108  as shown in FIG. 2, which may be connected to a float arm extension  110  by any suitable means, such as a threaded fastener  111 . The float arm extension  10  is preferably connected to the float arm  52  through an opening (not shown) located at the end of float arm  52  opposite the fingers  54  and  55 . Although the fluid detector shown in FIG. 2 is a float, other types of fluid detectors can be used, such as, for example, float switches, density based detectors, electrical resistance detectors, electrical capacitance detectors, pressure transducers, ultrasonic measuring devices, and optical measurement devices. 
     Referring now to FIG. 4, an actuator assembly  111  includes an elongate actuator  112  having an aperture (not shown) at one end and an elongate slot  116  at the other end. The third pivot pin  72  passes through the aperture of the actuator  112  to pivotally mount the actuator  112  about the pivot axis B between the fingers  76  and  77  of the first end of the spring  74 . 
     Referring now to FIGS. 4 and 5, the actuator assembly  111  includes a linkage, shown generally at  118 , having a pair of elongate arms  120 . A sixth pivot pin  122  passes through a first aperture  124  at one end of each arm  120 , and passes through the slot  116  of the actuator  112  to pivotally mount the linkage  118  to the actuator  112 . A seventh pivot pin  126  passes through a second aperture  128  at the other end of each arm  120  to pivotally mount the linkage  118  to each frame plate  28  at a generally circular slot  129 . An eighth pivot pin  130  passes through a third aperture  132 , intermediate the apertures  124  and  128 , of each arm  120 . The pivot pin  130  further passes through an aperture (not shown) at one end of a generally L-shaped valve holder  136  to pivotally mount the linkage  118  to the valve holder  136 . The other end of the valve holder  136  includes a generally hemispherical vent valve  138  and a steam inlet valve pin  140 . The vent valve  138  cooperates with the valve seat  45  to close and open the vent valve assembly  43 . 
     Bushings  104  are also provided to reduce friction and wear between the pivot pins  122  and  126 , and the corresponding apertures of the linkage arms  120  and the frame plate  28 . It will be understood that each of the pivot pins  122 ,  126 , and  130 , may be secured to the pump assembly by any suitable means, such as, for example, retaining clips  109 . 
     As best seen in FIG. 4, the pin  140  cooperates with the valve  34  of the inlet valve assembly  33 . When the float  108  is at its lowest position, as shown in FIG. 2, the inlet valve assembly  33  is closed and the vent valve assembly  43  is open. As the float  108  rises due to the fluid level rising in the tank  12 , the float  108  pivots about the pivot axis A. The pivot pin  98  engages the toggle  90  at the slot  96 . The toggle  90  in turn engages the spring  74  at the pivot pin  86 . As the float  108  continues to rise, the pivot pin  86  is urged downwardly, thereby compressing the spring  74 . 
     Referring now to FIGS. 2 and 4, when the float  108  reaches an upper tripping point, the energy stored in the spring  74  causes the second end of the spring  74  and the pivot pin  86  to snap downwards. The upper tripping point is defined as a line passing through pivot axes A, B, and C, when the pivot axis C moves to a point that is approximately co-linear with the pivot axes A and B. 
     Another important aspect of the invention is that the float  108  and its attached float arm  52  can travel freely through a first range of pivotal travel whereby the float pivots about the axis A, urges the pivot pin  98  downwardly within the arcuate slot  96  of the toggle  90  without engaging the mechanism  50 , and thereby without compressing the spring  74 . After the float  108  has traveled through a predetermined portion of its first range of pivotal travel, the float  108  and float arm  52  reach a point of maximum leverage relative to the spring  74 . The pivot pin  98  then engages a lower surface  96   a , shown in FIG. 7, of the slot  96  of the toggle  90 , thereby urging the toggle  90  downwardly and compressing the spring  74 . 
     When the second end of the spring  74  and the pivot pin  86  snap downwards through the upper tripping point, the spring arms  64  are caused to rotate about the pivot axis A, urging the pivot pin  72  and the attached actuator  112  upwardly within the arcuate slot  73  of each frame plate  28 . Downward movement of the pivot pin  86  is limited by the circular slot  88  of each frame plate  28 . The upward movement of the actuator  112  then causes the actuator  112  to engage the linkage  118 . 
     Referring now to FIGS. 4 and 5, upward movement of the actuator  112  causes the actuator  112  to engage the arms  120  of the linkage  118  at the pivot pin  122 , thereby causing the arms  120  to rotate about pivot pin  126 . The rotation of the arms  120  causes the valve holder  136  to rotate about the pivot pin  130  and simultaneously move upward. The upward movement of the valve holder  136  then causes the pin  140  to drive the valve  36  off the valve seat  35  to open the valve assembly  33 . The upward movement of the valve holder  136  further causes the vent valve  138  to be driven upward into sealing engagement with the valve seat  45  to close the vent valve assembly  43 . It should be realized that upward movement of the actuator  112  will continue until the valve  138  engages the valve seat  45 , and the vent valve assembly  43  is thereby closed. 
     In the preferred embodiment, the valve  138  is hemispherical in shape. However, it should be realized that the invention is not limited to the complementary shape of the valve  138  and the valve seat  45 , and that the invention can be practiced with any complementary shape for the valve  138  and the valve seat  45 . 
     As best seen in FIGS. 2 and 4, when the spring  74  snaps downward through the upper tripping point, the pin  60  of the float arm  52  engages a surface  62   a  of the arcuate slot  62  of each frame plate  28 , thereby preventing further rotation of the float arm  52 . 
     Once the valve assembly  33  is opened, a pressurized fluid, preferably steam, flows through the valve assembly  33  and develops a pressure within the tank  12  of sufficient magnitude to pump the accumulated fluid from the tank  12  though the fluid outlet valve  15 . 
     As the fluid level in the tank  12  decreases, the float  108  drops downward and pivots about the pivot axis A. The pivot pin  98  engages the toggle  90  at the slot  96 . The toggle  90  in turn engages the spring  74  at the pivot pin  86 . As the float continues to drop, the pivot pin  86  is urged upwardly in the arcuate slot  70  of each spring arm  64 , thereby compressing the spring  74 . When the float  108  reaches a lower tripping point, the energy stored in the spring  74  causes the second end of the spring  74  and the pivot pin  86  to snap upwards. Similar to the upper tripping point, the lower tripping point is defined as a line passing through pivot axes A, B, and C, when the pivot axis C moves to a point that is approximately co-linear with the pivot axes A and B. 
     As described with regards to the upward movement of the float  108 , a further important aspect of the invention is that the float  108  and its attached float arm  52  can travel freely during downward movement of the float  108  through a second range of pivotal travel whereby the float  108  pivots about the axis A, urges the pivot pin  98  upwardly within the arcuate slot  96  of the toggle  90  without engaging the mechanism  50 , and thereby without compressing the spring  74 . After the float  108  has traveled through a predetermined portion of its second range of pivotal travel, the float  108  and float arm  52  reach a point of maximum leverage relative to the spring  74 . The pivot pin  98  then engages an upper surface  96   b  of the slot  96  of the toggle  90 , thereby urging the toggle  90  upwardly and compressing the spring  74 . 
     When the second end of the spring  74  and the pivot pin  86  snap upward through the lower tripping point, the spring arms  64  are caused to rotate about the pivot axis A, urging the pivot pin  72  and the attached actuator  112  downwardly within the arcuate slot  73  of each frame plate  28 . Upward movement of the pivot pin  86  is limited by the circular slot  88  of each frame plate  28 . As best seen in FIGS. 2 and 4, when the spring  74  snaps upward through the lower tripping point, the pin  60  of the float arm  52  engages a surface  62   b  of the arcuate slot  62  of each frame plate  28 , thereby preventing further rotation of the float arm  52 . Additionally, as the actuator  112  moves downward, the pivot pin  72  engages a surface  73   a  of the arcuate slot  73  of each frame plate  28 , thereby stopping the downward movement of the actuator  112 . 
     Another important aspect of the invention is the elongate slot  116  of the actuator  112 . When the second end of the spring  74  and the pivot pin  86  snap upwards through the lower tripping point, the actuator  112  moves downward a predetermined distance relative to the linkage  118  without engaging the linkage  118 . After the actuator  112  has traveled the predetermined distance relative to the linkage  118 , an upper surface of the elongate slot  116  engages the pivot pin  122  of the linkage  118 , thereby causing the linkage  118  to pivot about the pivot pin  126 . The actuator  112  gains momentum as it travels the predetermined distance before engaging and applying a force to the linkage  118 , and thereby opening the vent valve assembly  43 . The force applied to the linkage  118  to open the vent valve assembly  43  is therefore improved over other commonly known pump assemblies. 
     The force generated by the downward movement of the actuator  112  causes the actuator  112  to engage the arms  120  of the linkage  118  at the pivot pin  122 , thereby causing the arms  120  to rotate about pivot pin  126 . The rotation of the arms  120  causes the valve holder  136  to rotate about the pivot pin  130  and simultaneously move downward. The downward movement of the valve holder  136  then causes the pin  140  to disengage the valve  36 , allowing the valve  36  to sealing engage the valve seat  35 , thereby closing the valve assembly  33 . The downward movement of the valve holder  136  further causes the vent valve  138  to be driven downward from the valve seat  45  to open the vent valve assembly  43 . 
     The principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.