Abstract:
The present invention relates to a reciprocating piston pump comprising: at least one cylinder with an inlet for a pressure medium; a piston slidable in the cylinder between a first and a second position, and forming a pressure chamber in the cylinder; a first valve member which is received in the piston and which in an open position mutually connects the cylinder spaces on either side of the piston; a second valve member which is received in the piston and which in an open position connects a pressure medium passage formed in the piston to an outlet of the pump; a resilient member urging the piston in the first position; an actuating member connected to the valve members and which are embodied such that in the first position the first valve member is closed and the second valve member is opened and in the second position the first valve member is opened and the second valve member is closed, wherein the piston is moved to the second position by the pressure medium.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims priority under 35 U.S.C. § 119 to application serial number 07075373.6 filed in the European Patent Office on May 15, 2007 entitled “RECIPROCATING PISTON PUMP OPERATING ON PRESSURE MEDIUM,” which is incorporated by reference into the instant application as if set forth verbatim. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to pumps, and more particularly to reciprocating piston pumps operated with a pressure medium. 
       BACKGROUND OF THE INVENTION 
       [0003]    Existing reciprocating piston pumps are used to transport a medium from a pump inlet connected to a tank to a pump outlet opening. These pumps are driven by a motor that slidably moves a piston of the pump in the cylinder, thereby forming a pressure chamber in the cylinder. By opening and closing valves at the appropriate times, the pressurized fluid is propelled out of the pump. However, existing pumps require separate motors and connecting means, thereby increasing the number of parts, maintenance etc. 
         [0004]    Accordingly there is a need for a reciprocating piston pump which is more efficient and does not require separate drive means. 
       SUMMARY OF THE INVENTION 
       [0005]    This objective is achieved with the reciprocating piston pump of the present invention. 
         [0006]    The piston of the pump will slide in the cylinder from a first to a second position by supplying the pump inlet with a pressure medium. Valve members are received or incorporated in the piston itself and are actuated by the actuating members. By opening and closing the valve members at the appropriate times, the pressure medium that is brought into the cylinder during the movement of the piston from a first position to a second position will be transferred to the other side of the piston during the piston&#39;s return from the second position to the first position. In one embodiment, during the return stroke to the first position, the first valve member is open and mutually connects the cylinder spaces on either side of the piston. During the movement of the piston from the first position to the second position, the pressure medium, which has been transferred from the pump inlet to the pressure chamber, is transported out of the pump via the pump outlet. During this piston stroke the second valve member is in an open position connecting the pressure chamber to the outlet. A pressure medium moves the piston from the first position to the second position in the cylinder, and a resilient member will urge the piston from the second position to the first position. The interplay of the resilient member and piston enables the piston pump to operate without requiring a separate motor for driving the pump. This results in a more efficient pumping and does not require separate drive means. 
         [0007]    A preferred embodiment of the piston pump according to the present invention comprises a first plunger for uptake of a first medium from a second inlet to a second chamber. 
         [0008]    The plunger moves from a first to a second position thereby creating an under-pressure that will cause uptake of a first medium through a second inlet of the pump. This enables transport of the first medium from a tank (or the like) to an outlet. Preferably, the pump comprises sealing means for sealing the second chamber against a return flow of medium. Advantageously, the pump comprises a connecting member connecting the first plunger with the piston to simultaneously move the plunger and piston. Through this simultaneous movement of the plunger and piston, both the pressure medium and the first medium are transported to the pump outlet. In other words, the movement of the piston, either by the pressure medium or the resilient means, causes uptake and transport of the first medium to the pump outlet. Preferably, the pump outlet for the first medium and the pressure medium is the same. Therefore, a mixture of the pressure medium with the first medium is provided. For example, in the case of the pressure medium being water and the first medium being a soap concentrate, such a mixture would result in a liquid soap ready for use. 
         [0009]    In a further preferred embodiment according to the present invention the pump further comprises a second plunger for uptake of a second medium from a third inlet to a third chamber. 
         [0010]    By moving the second plunger from a first position to a second position an under-pressure will be created in the third chamber. This will cause uptake of a second medium from a third inlet. This will enable transport of this second medium from a tank (or the like) to an outlet. Preferably, the pump comprises second sealing means for sealing the third chamber against a return flow of medium. Further, the second pump preferably comprises a second connecting member connecting the second plunger to the piston (and preferably also to the first plunger) to simultaneously move the piston and second plunger (and preferably the first plunger) for transport of the pressure medium, and second medium (and preferably also the first medium) to the pump outlet. In a preferred embodiment, the pump outlet for the pressure medium, the first medium, and the second medium are the same. This results in a mixture of these media in the outlet flow. For example, in the case of the pressure medium being water and the first and second media being soap concentrates, the outflow of the pump will be a liquid soap ready for use. Preferably, the third inlet is at a different position as the second inlet to enable uptake of two different media, or the same medium at different altitudes in a tank with different densities. In case of the third inlet taking media from the same tank it is possible to have a mixture at the pump outlet of the pressure medium and two different densities of the other medium thereby creating a consistent mixture. 
         [0011]    In a further preferred embodiment according to the present invention the pump a comprises float member for connecting the third inlet to the second chamber. 
         [0012]    By the use of the float member it is possible to keep the third inlet at the upper level of, for example, a storage tank with decreasing level as the pumping operation continues. With the float member keeping the third inlet at a different level as compared to the second inlet during the pumping operation density differences in a storage tank are compensated. Preferably, the float member comprises a pivoting member to ensure the third pump inlet remains above the second inlet. Also preferably, the float member comprises a lock for locking and unlocking the pivoting member. This enables the float member to float on the top surface of the fluid in, for example, a storage tank. Therefore, the third inlet can be positioned just below this top level. As fluid is removed by the pumping operation, and the level in the tank thus decreases, the float member will pivot around the pivoting member to remain floating on the medium and thereby keeping the third inlet just below this top level. By providing a lock it is possible to put the piston pump into a storage tank after which the lock is disabled and the float member unlocked. The piston pump may then start operation. In case the piston pump needs to be removed from the storage tank the float member may be retracted to its original position by enabling the lock. This may be relevant, for example, when a storage tank is not fully empty and the pump needs to be removed. 
         [0013]    In a further preferred embodiment according to the present invention the pump further comprises at least one shock absorber with a plunger. 
         [0014]    When the piston moves from the first position to the second position, and medium is transported from the pressure chamber to the pump outlet, part of the outgoing medium is temporarily stored by the absorber. This stored volume is output during the return movement of the piston from the second position to the first position due to the compressed air volume on the other side of the plunger. This smoothens the pump output. 
         [0015]    In a further preferred embodiment according to the present invention the pump further comprises disposing means for disposing an amount of an agent medium in at least one chamber. 
         [0016]    The disposing means will provide a certain amount of one or more agents into one of the chambers of the piston pump during a stroke of the piston and/or plungers. Such agent may include a colouring agent supplying a specific colour to the inlet space of the pressure medium, thereby colouring the outflow from the piston pump. This will be relevant e.g. in case the outflow of the piston pump has the same colour as the incoming flow. E.g. in case of the pressure medium being water and the first and/or second medium being a soap concentrate a colouring agent will enable to distinguish the ingoing water from the outgoing soap. Also other agents may be used to provide specific characteristics to the outflow of the piston pump. Preferably, the pump comprises connecting means for connecting the tank of agents medium to the pump. This enables the provision of a single piece of equipment for both the pump and the agent disposal means. Furthermore, by directly coupling the agent medium to the pump it is possible to use the movement of the piston for disposal of the agent in the main pressure chamber related to this piston. 
         [0017]    In a further preferred embodiment according to the present invention the pressure medium is a fluid. 
         [0018]    A fluid, like water, used for the pressure medium would allow for movement of the piston in the cylinder. Furthermore, as the piston is moved due to the resilient means, the fluid is transported to the pump outlet and preferably mixed with one or two other media like, for example, soap concentrate. Such soap concentrate may constitute of a mix of various chemicals with a rather large variation of molecular weight. This concentrate may be taken from a storage tank. Typically, after a relatively short period of time, such as about 5 minutes, it is possible to distinguish an upper part of, for example, 60% low density concentrate and a lower part of, for example, 40% higher density concentrate. To achieve a consistent outflow of soap at the pump outlet such a mixture must reflect the differences in density of the soap concentrate. In the example mentioned here, 60% of the soap concentrate has to be taken from the upper part by the third inlet of the pump and the remaining 40% of the lower part by the second inlet of the pump. Depending on the desired characteristics of the soap product, the ratio of soap to water will vary. Different ratios may be achieved by changing the dimensions of the pump parts. For example, different uptakes of volume from the storage tank by the second and/or third inlet will be possible. By choosing the second and third chambers of the desired dimensions it is possible to have an outflow with every desired concentrations of media. Although in the preferred embodiment the ratio of the first pressure chamber and second chamber is about 1:11, also ratios 1:10 and 1:12 are possible. However, it will be understood that far different ratios will be possible, such as anywhere between 1:1 and 1:100, depending on the density differences in the relevant media. This will include the ratios 1:23 and 1:35 that are also relevant for soap concentrates. 
         [0019]    The volumes of the chambers used by the first and second plunger have to be chosen according to the characteristics of the soap concentrate. In the example mentioned here, this ratio would be 2:3, although ratios between 1:2 and 2:1 would also be possible. However, it will be understood that ratios anywhere from 1:100 to 100:1 would also be possible. 
         [0020]    The invention further relates to a method for pumping at least one medium using the reciprocating piston pump according to the invention. Using this method the advantages mentioned before will be obtained. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]      FIG. 1  shows a reciprocating piston pump according to the invention put into a storage tank; 
           [0022]      FIG. 2  shows the piston pump of  FIG. 1  extracted from the storage tank; 
           [0023]      FIGS. 3A  and B show the piston pump of  FIG. 1  with the lock engaged and disengaged respectively; 
           [0024]      FIG. 4  shows the piston pump of  FIG. 1  with the float member rotating; 
           [0025]      FIGS. 5A  and B show the piston pump of  FIG. 1 ; 
           [0026]      FIG. 6  shows the valve members in the piston of the pump of  FIG. 5 ; 
           [0027]      FIG. 7  shows the shock absorber in the piston of the pump of  FIG. 5 ; 
           [0028]      FIG. 8  shows the mixing chamber for the two soap concentrates; 
           [0029]      FIG. 9  shows the second chamber; 
           [0030]      FIG. 10  shows the pivot axis of the floating means; 
           [0031]      FIG. 11  shows the second pump inlet; 
           [0032]      FIG. 12  shows the third chamber; and 
           [0033]      FIG. 13  shows an alternative configuration for the agent supply. 
       
    
    
     DETAILED DESCRIPTION 
       [0034]    Exemplary embodiments of the invention are described in detail below with reference to the appended figures, wherein like elements are reference with like numerals throughout. The figures are not necessarily drawn to scale and do not necessarily show every detail or structure of the various embodiments of the invention, but rather illustrate exemplary embodiments and mechanical features in order to provide and enabling description of such embodiments. 
         [0035]    A reciprocating piston pump is located in a storage tank  4  that is put on a pallet  6  ( FIG. 1 ). The piston pump  2  has an inlet  8  for supply of water as a pressure medium and an outlet  10  for the outgoing flow. The pump  2  comprises a second inlet or inlets  12  and a third inlet or inlets  14  for uptake of a relatively low density fluid  16  and a relatively high density fluid  18 , respectively. The pump  2  is connected to tank  4  with connector  20 . The pump  2  is put at the bottom of the tank  4  with inlet  14 . As the volume of the fluid in tank  4  is relatively high the float member  22  will be in an approximately horizontal position after it pivots around pivot axis  24 . To enable extraction of pump  2  from the tank  4  the float member  22  is locked against the pump ( FIG. 2 ). Also in case the pump  2  is entered into the tank  4  the lock is engaged and will only be disengaged after pump  2  has reached its position inside tank  4  ( FIGS. 3A and 3B ). After disengaging the lock the float member  22  will rotate around pivot axis  24 , provided there is sufficient level of fluid in tank  4  ( FIG. 4 ) to buoy the float member. The float member  22  pivots in the direction indicated by arrow A. 
         [0036]    Pump  2  ( FIGS. 5A and 5B ) comprises a housing  26  wherein a main piston  28  slides. The piston  28  is connected to a central rod  30 . The pressure medium, in this case water, enters the pump  2  at the inlet body  32 . As soon as the pressure medium is allowed to enter the pump  2 , it will cause the piston  28  to move downwards. Due to this downward movement the pressure chamber  34  will become smaller thereby increasing the pressure inside it. To relieve this increased pressure, the fluid in chamber  34  can escape through valve member  38  (when open) and leave the pump  2  at the pump outlet  36 . 
         [0037]    Valve member  38  ( FIG. 6 ) comprises an upper valve part  40  and a lower valve part  42 . The valve members  40  and  42  are received slidably in the piston  28 . The protruding ends of the valve bodies form actuators which interact respectively with stops formed inside the chamber  34  by the fluid head disk  44  and with a stop at the opposite end of the cylinder formed by the inlet body  32 . In the position shown in  FIGS. 5 and 6 , the pressure medium flows via the inlet body  32  towards the piston  28 . The pressure medium pushes the piston  28  downwards counter to the force of a spring. The fluid in chamber  34  flows through the opening between the lower valve part  42  and the piston channel through the pump outlet  36 . As the actuator or valve spring  46  meets its stop at the end of the downward movements, the valve member  38  will move relative to the piston  28  and the connection between outlet  36  and room  34  will be closed. At the same time the upper valve part  40  will be opened and both rooms opposite of the piston  28  will be connected. As the spring urges the piston  28  back to this beginning position, as shown in  FIGS. 5 and 6 , the fluid will be transported from above the piston  28  to the chamber  34  below the piston  28 . At the end of this return stroke when the piston  28  returns to the beginning position the valve spring  46  will move the valve member  38  relative to the piston  28  so that the next cycles may start. 
         [0038]    Piston  28  comprises three shock absorbers  48  ( FIG. 7 ). The shock absorber  48  contains a shock absorber cap  50 , a shock absorber barrel  52  and a shock absorber piston  54 . This will compensate for undesired pressure variations and results in a more constant outflow. Fluid enters the space between absorber piston  54  and the bottom of barrel  52 . The fluid urges the piston  54  upward by allowing fluid to enter the absorber  48  through opening  55 , thereby increasing the air pressure in the space above piston  54 . Fluid is collected in the space below piston  54  during the movement of the main piston  28  from its upper to its lower position. In the return movement the air pressure above piston  54  pushes piston  54  downward thereby transporting the fluid to the outlet. Piston  54  is cup-shaped to increase the volume of the shock absorber  48 . 
         [0039]    The central rod  30  is connected to a two staged plunger. The large upper plunger  56  is connected to the piston  28  with an area constituting a ratio between the pressure medium and the second (and further) medium of about 11:1. In the embodiment shown in the figures the lower and smaller plunger section has a surface area of 60% of the upper plunger leaving a ring shaped area of 40%. In the shown embodiment 60% of the second and further medium is taken from the upper part of the storage tank volume, while the remaining 40% are taken from the bottom of this storage tank. The piston rod  30  is connected with the piston  28  and the plungers  56  and  58 . A downward movement of piston  28  results in a simultaneous downward movement of the upper plunger  56  and lower plunger  58 . The chamber  60  between the lower plunger  58  and the fluid at fluid head  62  is emptied due to the downward movement of the upper plunger  56 . The chamber  64  is also emptied in this same downward movement of the piston  28 . 
         [0040]    The upper outlet valve  66  ( FIG. 8 ) is open during the downward movement of the piston  28  thereby allowing the medium in chamber  60  to be transported towards piston  28  and the pump outlet  36 . An upper support ring  68  lies against fluid head disk  44  and comprises upper support ring inner seal  70 , an upper outlet outer seal  72  and also an upper support ring inner seal  74 . The outlet valve  66  is urged back from its second position to its first position due to the upper outlet spring  76 . 
         [0041]    The lower plunger  58  ( FIG. 9 ) in its downward movement moves the lower outlet valve  78  and allows transport of the medium in chamber  64  towards piston  28  and pump outlet  36 . The lower outlet spring  80  closes valve  78  when returning from its second position to its first position. 
         [0042]    The central rod  30  comprises a lower seal  82 . The fluid head extension  84  is connected to a lower support ring  86 . The support ring  86  contains inner seals  88  and lower seals  90 . The fluid head extension  84  contains an upper seal  92  and lower seal  94 . The valve  78  contains an outer seal  96 . 
         [0043]    The chamber  64  is supplied with medium through suction pipe  98  in the piston movement from the second position back to its first position. The medium is supplied through suction pipe  98  towards room  64  and an assembly  98  prevents a return flow of medium back into suction pipe  98 . Assembly  100  ( FIG. 9 ) comprises a lower inlet insert  102 , a lower inlet body  104 , a lower inlet gland  106  and a lower inlet poppet  108 . Furthermore, the assembly  100  is provided with a lower inlet body outer seal  110 , a lower inlet poppet seal  112  and two lower inlet body inlet seals  114 . 
         [0044]    The suction pipe  98  is connected to a pivotable inlet through coupling assembly  116  ( FIG. 10 ). The assembly  116  pivots around a pivot axis created by balance pivot bolt  118 . The assembly  116  further comprises two balance connectors  120 , two balance pivot bearings  122  and the balance pivot  124 . The assembly  116  is sealed using four balance intake extension seals  126 , two balance pivot seals  128  and two balance connector seals  130 . The assembly  116  is connected to its inlet through a balance open union  132  and a balance float bolt  134  leading to the inlet located in the balance float  136 . The inlet of floating part  136  ( FIG. 5A ) has a counter weight  138  that is connected by a horse shoe connection  140  with the counter weight extension  142 . These parts are connected with four balance connectors closed unions  144 . 
         [0045]    Room  60  is supplied with medium through flexible suction pipe  146  that is connected to the corresponding inlet assembly  148  ( FIG. 11 ). The assembly  148  comprises a bottom disk  150  and a bottom disk insert  152 . The assembly  148  further comprises a bottom disk retaining ring  154 . 
         [0046]    The suction pipe  146  supplies the medium at the other side through an upper inlet assembly  156  ( FIG. 12 ). Each of the two suction pipes  146  inputs the medium through a separate upper inlet assembly  156 . Each assembly  156  comprises an upper inlet poppet  158 , a lower supporting ring outer seal  160  and an upper inlet spring  162 . 
         [0047]    To enable intake of medium from the top level of a liquid in a storage tank the float member  22  is allowed to pivot around pivot axis  24 , as described before. To enable removal of the pump  2  from the storage tank it is required that the floating device returns to its original position. This is achieved by a locking assembly comprising a lock spring  164 , a mounting gland  166 , a lock sleeve  168 , a lock body  170 , a large balance protector  172  and a small balance protector  174  (see  FIG. 5 ). The assembly further comprises a lock body support  176 . The balance protector  174  is connected to the pivoting assembly  156  through a rod  178 , washer  180  and nut  182  with bolt  184 . The large protector  172  is connected through the threaded rod  186 , washer  188  and nut  190 . The protectors  172 ,  174  are connected to the pump  2  ( FIG. 5B ) and do not pivot with the float member  22 . The lock body  170  comprises a cam  171  that engages the float member  22 . By movement of the lock body  170  and cam  171 , the float member  22  is locked or unlocked for its pivotal movement. When unlocked the float member  22  starts to pivot, depending on the level of fluid in the tank  4 , and engages the lock body  170  when reaching a horizontal level. 
         [0048]    To urge the piston  28  from its second position to its first position, spring  204  engages spring support  206  with spring bushing  208 , as shown in  FIG. 5 . On its other end spring  204  lies against spring support  210  that is connected to inlet body  32 . The rod  200  consists of a bottom part  212  and an upper part  214  that are connected through a union  216  comprising a seal  218 . Inlet body  32  is sealed with an inlet body seal  220 . The spring support  210  is sealed with seals  222 ,  224  and backup seal  226 . 
         [0049]    In the pump  2 , agent medium is supplied from agent supply chamber  192 . As shown in  FIG. 13 , the agent medium is supplied using a separate plunger  228 . The diameter extension  230  at the end of the rod, changing from 44 to 46 mm, drives the plunger  228 . Thereby the movements of this plunger  228  are connected with piston  28 . In this embodiment the displacement of the plunger  228  would be 1 mm with a diameter of 10 mm resulting in a volumetric displacement of about 79 mm 3 . The inlet and outlet valves for the plunger comprise steel balls  232  and  234  in a bore of about 3.2 mm with a stroke of about 0.4 mm. The balls seal in one direction. A rubber spring  236  pushes the large ball  238  and the plunger  228  against the rod. The rod extension compresses the spring  236 . As a result the spring  236  increases its diameter filling the space inside the plunger and insert  240  preventing a substantial dead volume. This configuration will, in relevant cases, ensure a more constant supply of agent medium and enable a smooth start-up of the agent supply. 
         [0050]    In an alternative configuration, agent medium is supplied from an agent supply room  192 , shown in  FIG. 5 . This room  192  comprises an agent filler cap  194  for refilling and a top lid. The room  192  is sealed with a filler cap seal  198 , through which the top rod  200  may be moved. This rod is supplied with a top cap  202 . In the end of the stroke of the piston  28  moving from the first position to the second position a few droplets of the agents medium are pushed out of the agent supply room  192  into the room above the piston  28 . This is accomplished by an agent pusher that at the end of the stroke, enters into a cone of spring support  210  thereby pushing the desired droplets of agents medium by the seal into the room above the piston  28  during the movement from first position to the second position. 
         [0051]    As an example of an alternative embodiment, the pressure medium may be water and the first and second medium may be a soap concentrate. Other media will also be possible. In addition, it will be possible to supply all inlets with different media from different storage tanks. Also, it would be possible to have a supply of agent medium already in the pressure medium instead of a separate supply room. The configuration of the pump may be changed, for example in that room  60  is connected to the inlet of the float member instead of the bottom inlet. 
         [0052]    Various modifications and alterations of the invention will become apparent to those skilled in the art without departing from the spirit and scope of the invention, which is defined by the accompanying claims. For example, it should be noted that steps recited in any method claims below do not necessarily need to be performed in the order they are recited. For example, in certain embodiments, steps may be performed simultaneously. The accompanying claims should be constructed with these principles in mind. 
         [0053]    Any element in a claim that does not explicitly state “means for” performing a specified function or “step for” performing a specified function is not to be interpreted as a “means” or “step” clause as specified in 35 U.S.C. § 112, ¶16.