Abstract:
A hydraulically driven diaphragm pump ( 1 ) comprises: a housing having a side ( 8 ) arranged to be connected with a membrane unit, a pumping element having a piston barrel ( 14 ) and a piston ( 17 ); and a fluid reservoir ( 10 ) wherein the pumping element is arranged to pump a working fluid from the fluid reservoir ( 10 ) during the delivery stroke. The diaphragm pump further comprises means ( 18,26 ) for applying a vacuum to the fluid reservoir ( 10 ) in order to improve the delivery accuracy and avoid malfunctioning of the pump. The diaphragm pump may further comprise a regulation chamber having adjusting means for adjusting the size of an active volume of the regulation chamber, thereby adjusting the pump delivery.

Description:
FIELD OF INVENTION 
       [0001]    The invention relates to an improved diaphragm pump and a method of optimizing fluid flow in said pump said pump. 
       BACKGROUND OF THE INVENTION 
       [0002]    In known diaphragm pumps the pump volume i.e. the amount of fluid pumped per pump stroke, is often regulated by controlling how far the piston in the pump element may be retracted. This means that when the piston is driven by an eccentric, the piston and the eccentric will not be in contact at all times when the piston cannot be retracted fully (when the pump is adjusted to have a lower pump volume). A piston not in contact with the eccentric at all times will follow the eccentric during part of the rotation of the eccentric and will disconnect from the eccentric when the piston cannot be retracted further. When the piston and eccentric again make contact this will be with a sudden impact which obviously is undesired as it increases the wear on the moveable parts of the diaphragm pump. However, the alternative means of adjusting the pump volume have until now been complex solutions with a number of additional moveable parts which increase the manufacturing costs as well as maintenance requirements are significantly heightened. 
         [0003]    Furthermore, in some situations there is a risk that the membrane unit is not fully filled or emptied e.g. due to problems with fluid flow inside the pump. 
       SUMMARY OF THE INVENTION 
       [0004]    In a first aspect of the diaphragm pump according to the present invention is provided a pump with simple and low-maintenance means for adjusting the pump volume, 
         [0005]    In a second aspect of the diaphragm pump according to the present invention is provided a pump which allows regulation of pump fluid in the hydraulic chamber by alternative means providing a diaphragm pump with a reliable construction requiring less maintenance, 
         [0006]    In a third aspect of the diaphragm pump according to the present invention is provided a pump which allows regulation of air in the hydraulic chamber by alternative means providing a diaphragm pump with a reliable construction requiring less maintenance, In a fourth aspect of the diaphragm pump according to the present invention is provided a pump which has a precise pump volume. 
         [0007]    These and other objects and advantages are provided by the present invention by a diaphragm pump comprising a housing, arranged to be connected with a membrane unit, said diaphragm pump further comprising a pump element having a piston barrel and a piston, said diaphragm pump further comprising a fluid reservoir wherein the pump element is arranged to pump a pump fluid from the fluid reservoir and/or piston barrel during a first part of a piston stroke, said diaphragm pump further comprising a regulation chamber, wherein said regulation chamber is arranged with adjustment means for adjusting the size of a volume of the regulation chamber and wherein the pump volume of the diaphragm pump is adjusted by the adjustment means. 
         [0008]    Thus by the present invention is provided a pump which enables the adjustment of the pump volume by adjusting the volume of a regulation chamber into which a part of the fluid is pressed during part of a pump stroke. The use of the regulation chamber thus provides a diaphragm pump with a simple way of regulating the pump volume. Further the regulation of the pump volume via the regulation chamber can be achieved with the use of few movable parts and said parts which may have a limited need for maintenance compared to known systems. Hereby the pump according to the present invention is improved with regards to manufacturing, use and maintenance compared to known diaphragm pumps. 
         [0009]    The present diaphragm pump is preferably a main part contained in a housing which is arranged to be connected to a membrane unit. 
         [0010]    In use the housing is connected to a membrane unit and may be inserted into a line comprising a fluid to be pumped. 
         [0011]    The membrane unit comprises means for attaching the membrane unit to the housing and a membrane. Depending on the type of fluid to be pumped the parts of the membrane unit can be made of different materials in order to e.g. ensure that the membrane unit parts are not corroded by the fluid to be pumped or pump fluid. For example the membrane and other membrane unit parts can be of metal, plastic etc. 
         [0012]    Other parts of the membrane unit may also be made of selected materials in order to have desired properties such as stability, strength, low weight, not being corroded by different fluids or pump fluids etc. 
         [0013]    According to the present invention a pump fluid is pumped into the membrane unit, by the action of the pump element, thereby displacing the membrane. The pump volume is thus given by the displacement of the membrane: a small displacement leads to a small pump volume and a large displacement of the membrane leads to a large pump volume. 
         [0014]    When the piston of the pump element presses pump fluid from the fluid reservoir and/or piston barrel into the membrane unit, the membrane is displaced as a function of the increased amount of fluid in the membrane unit. When a part of the pump fluid is allowed to flow into the regulation chamber less pump fluid is left in the hydraulic chamber i.e. volume of the membrane unit to apply pressure on the membrane and thus the pump volume is decreased. 
         [0015]    When the active volume of the regulation chamber is increased more fluid can flow into the regulation chamber thus decreasing the displacement of the membrane leading to a decreased pump volume. 
         [0016]    When the active volume of the regulation chamber is decreased less fluid can flow into the regulation chamber thus increasing the displacement of the membrane leading to an increased pump volume. 
         [0017]    The active volume is the amount of pump fluid which can be contained in the regulation means. I.e. the active volume is adjusted by the adjustment means. 
         [0018]    When connected to the membrane unit there is fluid communication between the fluid reservoir, membrane unit and regulation chamber. 
         [0019]    The diaphragm pump according to the present invention is to be arranged in relation to e.g. a line wherein a fluid F is passing. When the membrane of the present pump is forced to be displaced the fluid F in the line is pushed forward i.e. pumped through the line. Thus, when the displacement of the membrane is adjusted by the adjustment means the amount of fluid F pumped by the diaphragm pump is adjusted. Hereby is provided a diaphragm pump which may be adjusted to pump a very precise amount of fluid F by each stroke of the piston element i.e. by each displacement of the membrane. 
         [0020]    The piston of the piston element moves in a reciprocating motion when performing a piston stroke. During the piston stroke the piston is initially in a first retracted position wherefrom the piston moves towards a fully advanced position and then back to the first retracted position. The movement from the first retracted position to the fully advanced position is the first part of the stroke and the movement of the piston from the fully advanced position back to the first retracted position is the second part of the stroke. 
         [0021]    During the first part of the stroke fluid is pumped from the fluid reservoir and/or the inside of the piston barrel to the membrane unit (if a membrane unit is attached to the diaphragm pump) and the membrane is positively displaced so that the volume of the membrane unit is increased. During the second part of the piston stroke fluid can be passed from the membrane unit and at least into the piston element thereby negatively displacing the membrane so that the volume of the hydraulic chamber is decreased. 
         [0022]    The adjustment means may provide a continuous adjustment of the active volume of the regulation chamber thereby providing a smooth and step-less regulation of the pump volume. Alternatively the adjustment means allows the adjustment of the active volume of the regulation chamber to be in a number of discrete values thereby providing regulation of the pump volume to a number of specific values. 
         [0023]    Preferably the adjusting means is a secondary piston so that when the pump element pumps pump fluid into the membrane unit and pump fluid is pressed into the regulation chamber the secondary piston is forced back by the pressure of the fluid. Preferably the secondary piston is moveable against a bias, e.g. a spring, so that when the pressure from the pump fluid on the secondary piston is relieved the secondary piston will be pushed forward thereby helping to empty the regulation chamber from fluid. 
         [0024]    Advantageously the maximum stroke of the secondary piston is regulated to adjust the volume of the regulation chamber. For example a screw, bolt or similar is used to adjust how far back the secondary piston may be pushed by the fluid thereby adjusting how much fluid may be accommodated in the active volume of the regulation chamber. 
         [0025]    It is also possible that other types of locks or stops are arranged to limit the motion of the secondary piston in order to adjust the active volume. 
         [0026]    In preferred embodiments there is direct and preferably free fluid communication between fluid reservoir and the membrane unit at least when the piston is fully retracted as this enables that the amount of fluid in the membrane unit is “reset” to a predefined value. Thus fluid may flow, preferably freely, into or out of the membrane unit during some point of each stroke without the need for complex solutions with valves etc. to keep the amount of fluid in the regulation chamber at a desired value or in a desired range. 
         [0027]    Preferably the piston barrel comprises at least one inlet opening which allows fluid to flow to the hollow of the piston barrel from the fluid reservoir when the piston is retracted. Fluid may also flow from the hollow of the piston barrel to the fluid reservoir through the inlet openings if desired i.e. if it is needed to adjust to the amount fluid in the membrane unit. In many preferred embodiments the at least one opening is located in an area of the piston barrel away from the ends of the piston barrel. 
         [0028]    In some advantageous embodiments there is fluid communication from the membrane unit through the piston element at least when the piston is fully retracted. In these embodiments fluid is allowed to pass through the inlet openings to and from the fluid reservoir. 
         [0029]    Advantageously the diaphragm pump comprises means for applying a vacuum to the fluid reservoir preferably during second part of the stroke. By applying the vacuum to the fluid reservoir, as the piston is retracted, i.e. during the second part of the stroke the suction withdrawing fluid from the hydraulic chamber and regulation chamber is enhanced and thereby helping to empty fluid from the hydraulic chamber and regulation chamber. In many advantageous embodiments all or nearly all pump fluid is withdrawn from the membrane unit. 
         [0030]    When the hydraulic chamber and regulation chamber is completely emptied from fluid or emptied to a well-known, degree the precision of the pump can be very high thereby allowing not only a very efficient pump but also a pump with a very well defined pump volume pr. stroke. 
         [0031]    In some preferred embodiments the vacuum ensures that all oil or substantially all pump fluid is sucked out of the membrane unit and the membrane is sucked against the end plate of the diaphragm pump. 
         [0032]    The application of the vacuum also has the advantage that there will not be a build up of pump fluid in the membrane unit caused by mall functioning valves etc. and thereby ruptures of the membrane is avoided. 
         [0033]    The application of vacuum also ensures that no air bubbles is present in pump fluid, membrane unit and/or regulation chamber as these will be sucked out and into the fluid reservoir. This is an advantage during ordinary operation but provides a significant improvement after pump fluid changes or during e.g. start-up of a new pump, both situations where unwanted air may be present in the system and where the present method and apparatus for applying vacuum to the fluid reservoir significantly reduce the time before optimized operation is achieved. 
         [0034]    In general a diaphragm pump connected with means for applying vacuum to a fluid reservoir of the diaphragm pump and a method for applying vacuum as described herein or similar is advantageous even if the diaphragm pump does not contain a regulation chamber as regulation means. Thus a membrane pump with means for applying vacuum may have the above advantages of the vacuum even without the regulation chamber. 
         [0035]    Preferably the means for applying a vacuum to the fluid chamber is a vacuum pump element as a pump element provides an efficient and low maintenance means for providing the vacuum. Also a vacuum pump element naturally can provide a pressure during one part of the stroke and a vacuum during another part of a stroke thereby bot sucking and pushing fluid through the inlet openings. 
         [0036]    If the fluid chamber and vacuum pump element is in fluid communication via a channel the vacuum pump element can be positioned relatively to the fluid reservoir in any desired position, thereby enabling an optimized design of the pump. Thereby for example the pump can be compact. 
         [0037]    Preferably the fluid reservoir comprises a fluid volume and a volume of gas during operation, as the pump fluid most often will be un-compressible and therefore a volume of an expandable/compressible gas or fluid may be needed to utilize the vacuum pump element. 
         [0038]    If the channel is in communication with the fluid volume fluid is drawn through the channel by the action of the vacuum means meaning i.e. pump fluid and not gas is sucked and pressed through the channel. Preferably the channel is arranged to be in communication with the fluid volume in a manner and position reducing the amount of debris, particles or other unwanted contaminants found in the pump fluid which is sucked into the channel by the action of the means for applying vacuum. 
         [0039]    If the piston of the pump element and a piston of the vacuum pump element are operated at least in part by common means a simple pump with fewer movable parts is achieved as each of the pump element and vacuum pump element does not need driving means assigned only to them. Further the common driving means also ensure that the pump element and vacuum pump element are operated in a coordinated motion. 
         [0040]    During the stroke the movement of the piston may be driven by a force on the piston rod. The force may e.g. be provided by a motor. 
         [0041]    Preferably at least the piston of the pump element is driven by a connecting rod and crank as this ensures a smooth and powerful movement of the pump element and also may provide a quiet operation of the pump. However other means such as only an eccentric may also be used. 
         [0042]    The pump volume is adjusted by adjusting the amount of fluid in the membrane unit (by adjusting how much fluid may flow into the regulation chamber from the membrane unit) in contrast to known systems where e.g. the maximum retraction of the piston is used to regulate pump volume. 
         [0043]    The choice of starting point i.e. the initial position in the descried piston movement is chosen as a matter of example and to enable a clear description. In use the movement of the piston head may start e.g. in the fully advanced position or in a position chosen to fit a specific situation, pump design etc. 
         [0044]    Preferably the piston, vacuum piston and/or secondary piston has a circumferential sealing in order to provide a sealed fit between the piston, vacuum piston and/or secondary piston and the piston barrel, vacuum piston barrel and/or secondary piston barrel respectively. 
         [0045]    If the seal is at least in part a PVDF seal or a reinforced PVDF seal the friction between the seal on the piston, vacuum piston and/or secondary piston and the piston barrel, vacuum piston barrel and/or secondary piston barrel respectively can be an effective seal while the friction between the seal on the piston, vacuum piston and/or secondary piston and the piston barrel, vacuum piston barrel and/or secondary piston barrel respectively can be minimized. Further a PVDF seal is durable a feature which is also desirable in the present context. Preferably the PVDF seal or enforced PVDF seal is supported by an O-ring. 
         [0046]    Materials like Teflon, carbon, metals, rubber etc. can also be used for seal materials alone or together with other materials. 
         [0047]    In advantageous embodiments at least one of the piston, vacuum piston or secondary piston is in two parts in order to be able to arrange a non-flexible circumferential sealing or a sealing with limited flexibility in a circumferential recess in the piston. 
         [0048]    According to the present invention the diaphragm pump can be acquired together with or without the membrane unit. According to the present invention the diaphragm pump can be acquired with the membrane unit connected to the housing or with the membrane unit detached from the housing. 
         [0049]    The housing may be of a solid block of e.g. a metal such as aluminium. Alternatively the housing is assembled from units for example containing the fluid reservoir, regulation chamber, vacuum pump element etc. respectively. 
         [0050]    Preferably the diaphragm pump is quiet in operation a feature which is enabled by the design and arrangement of the features as described above. 
         [0051]    Preferably the membrane pump can supply between 0-100 bar but the membrane pump may also provide at least 130, 140, 150 or 170 bar. This ability to reach high pressures is due to the special design of the over-all membrane pump including the pistons with seals. 
         [0052]    The present invention also relates to a method of adjusting the pump volume of a diaphragm pump comprising the steps of
       providing a diaphragm pump with a housing, a membrane unit, means for moving the membrane to perform a pumping motion, and a regulation chamber,   adjusting the active volume of the regulation chamber thereby adjusting the degree of maximum displacement of the membrane.       
 
         [0055]    As described above there are important advantages in adjusting the pump volume by adjusting the volume of an regulation chamber for example the pump volume may be adjusted without effecting the operation of the means for moving the membrane to perform a pumping motion. The means for moving the membrane to perform a pumping motion may advantageously be a pump element as descried above. 
         [0056]    Preferably the method is performed with a diaphragm pump as described above providing the described advantages and technical effects from the membrane pump according to the present invention to the method according to the present invention and vice versa. 
         [0057]    In a fourth aspect of the present invention is provided a pump which is arranged to have a more reliable fluid flow inside the diaphragm pump. 
         [0058]    This and other advantages are achieved by a diaphragm pump comprising a housing, arranged to be connected with a membrane unit, said diaphragm pump also comprising a pump element having a piston barrel and a piston the diaphragm pump further comprising a fluid reservoir wherein the pump element is arranged to pump a pump fluid from the fluid reservoir and/or piston barrel during a first part of a piston stroke said diaphragm pump further comprising means for applying a vacuum to the fluid reservoir at least during part of a second part of a piston stroke. When the diaphragm pump comprises means for applying a vacuum to the fluid reservoir it is possible to enhance the effect of the piston element pumping fluid in and out of the diaphragm unit. 
         [0059]    The piston of the piston element moves in a reciprocating motion when performing a piston stroke. During the piston stroke the piston is initially in a first retracted position wherefrom the piston moves towards a fully advanced position and then back to the first retracted position. The movement from the first retracted position to the fully advanced position is the first part of the stroke and the movement of the piston from the fully advanced position back to the first retracted position is the second part of the stroke. 
         [0060]    During the first part of the stroke fluid is pumped from the fluid reservoir and/or pump element to the membrane unit (if a membrane unit is attached to the diaphragm pump) and the membrane is positively displaced so that the volume of the membrane unit is increased. During the second part of the piston stroke fluid can be passed from the membrane unit and at least into the piston element thereby negatively displacing the membrane so that the volume of the hydraulic chamber i.e. volume of the membrane unit is decreased. 
         [0061]    By applying the vacuum to the fluid reservoir, as the piston is retracted, i.e. during the second part of the stroke the suction withdrawing fluid from the hydraulic chamber is enhanced and thereby helping to empty fluid from the hydraulic chamber. In many advantageous embodiments all or nearly all pump fluid is withdrawn from the membrane unit. 
         [0062]    When the hydraulic chamber is completely emptied from fluid or emptied to a well-known, degree the precision of the pump can be very high thereby allowing not only a very efficient pump but also a pump with a very well defined pump volume pr. stroke. 
         [0063]    In some preferred embodiments the vacuum ensures that all fluid or substantially all pump fluid is sucked out of the membrane unit and the membrane is sucked against the end or end plate of the diaphragm pump. 
         [0064]    The application of the vacuum also has the advantage that there will not be a build up of pump fluid in the membrane unit caused by mall functioning valves etc. and thereby ruptures of the membrane is avoided. 
         [0065]    The application of vacuum also ensures that no air bubbles are present in pump fluid and/or membrane unit as these will be sucked out and into the fluid reservoir. This is an advantage during ordinary operation but provides a significant improvement after pump fluid changes or during e.g. start-up of a new pump, both situations where unwanted air may be present in the system and where the present method and apparatus for applying vacuum to the fluid reservoir significantly reduce the time before optimized operation is achieved. 
         [0066]    In several embodiments the means for applying a vacuum is a vacuum pump element having a vacuum barrel and a vacuum piston as such vacuum pump elements can provide simple and reliable means requiring only a minimum of maintenance. A reciprocating vacuum piston may also provide a vacuum in the fluid reservoir during one part of the motion of the vacuum piston and may push fluid back into the fluid reservoir from the vacuum pump element during another part of the motion of the vacuum piston. When fluid is pushed back into the fluid reservoir the pressure in the fluid reservoir is increased and fluid may be pressed into the pump element from the fluid reservoir when the inlet openings are free. 
         [0067]    Preferably there is direct fluid communication between fluid reservoir and the membrane unit at least when the piston is fully retracted in order to allow a flow of fluid and balancing of pressures. 
         [0068]    Preferably the piston barrel comprises at least one inlet opening which allows fluid to flow to the hollow of the piston barrel from the fluid reservoir when the piston is pushed forward towards the advanced position. Fluid may also flow from the hollow of the piston barrel to the fluid reservoir through the inlet openings when there is applied a vacuum to the fluid reservoir and the piston is retracted to free the inlet openings. In many preferred embodiments the at least one opening is located in an area of the piston barrel away from the ends of the piston barrel. For example the openings can be positioned to be free from the piston (i.e. open) only when the piston is fully retracted or just before/after the piston is in its fully retracted position. 
         [0069]    When a vacuum and alternatingly a pressure is applied to the fluid reservoir by the vacuum means fluid may be sucked and pushed through the inlet openings. 
         [0070]    Thus in some advantageous embodiments there is fluid communication from the membrane unit through the piston element at least when the piston is fully retracted. In these embodiments fluid is allowed to pass through the inlet openings to and from the fluid reservoir when the inlet openings are free from the piston. 
         [0071]    If the fluid chamber and vacuum pump element is in fluid communication via a channel the vacuum pump element can be positioned relatively to the fluid reservoir in any desired position, thereby enabling an optimized design of the pump. Thereby for example the pump can be compact and/or optimized with respect to moving parts etc. 
         [0072]    Preferably the fluid reservoir comprises a fluid volume and a volume of gas during operation, as the pump fluid most often will be un-compressible and therefore a volume of an expandable/compressible gas or fluid is needed to utilize the vacuum pump element. 
         [0073]    If the channel is in communication with the fluid volume, fluid is drawn through the channel by the action of the vacuum means meaning i.e. pump fluid and not gas is sucked and pressed through the channel. Preferably the channel is arranged to be in communication with the fluid volume in a manner and position reducing the amount of debris, particles or other unwanted contaminants found in the pump fluid which is sucked into the channel by the action of the means for applying vacuum. 
         [0074]    If the piston of the pump element and a piston of the vacuum pump element are operated at least in part by common means a simple pump with fewer movable parts is achieved as each of the pump element and vacuum pump element does not need driving means assigned only to them. Further the common driving means also ensure that the pump element and vacuum pump element are operated in a coordinated motion. 
         [0075]    During the stroke the movement of the piston may be driven by a force on the piston rod. The force may e.g. be provided by a motor. 
         [0076]    Preferably at least the piston of the pump element is driven by a connecting rod and crank as this ensures a smooth and powerful movement of the pump element and also may provide a quiet operation of the pump. However other means for driving the pistons can also be used. 
         [0077]    The piston barrel and the vacuum barrel can be connected end to end in order to provide a structurally simple device. 
         [0078]    The piston of the pump element and the piston of the vacuum pump element can be connected allowing the two pistons to move in a synchronized manner. If the two pistons are connected so that they reciprocate along a common axis or parallel axis a common driving means can be used as well as number of movable parts may be minimized. 
         [0079]    The two pistons can be static with respect to each other either by being made in one piece or by being made of several parts assembled into one element. 
         [0080]    If the piston of the pump element and the piston of the vacuum pump element are movable with respect to each other it can be possible to adjust how much vacuum is applied to the fluid reservoir. 
         [0081]    E.g. if the vacuum piston partly extends over the piston of the pump element it is possible to allow the piston and vacuum piston to move relatively to each other during a stroke or during parts of a stroke in order to be able to adjust the pressure/vacuum applied by the vacuum piston. 
         [0082]    In embodiments where the piston and vacuum piston are arranged to move relatively to each other during at least part of a stoke means for stopping or limiting the relative motion can be arranged on one or more parts of the piston element or vacuum piston element. When the relative motion can be fixed, limited and/or biased it may be possible to regulate the vacuum pressure applied by the vacuum piston during a stroke. 
         [0083]    In several embodiments the diameter of the piston of the pump element is small than the diameter of the vacuum piston of the vacuum pump element, as this provides a simple way of having two connected pistons in a one, two part or multi part housing. 
         [0084]    The application also relates to a method of applying a vacuum to the fluid reservoir of a diaphragm pump comprising the steps of
       providing a diaphragm pump comprising a housing, a membrane unit, means for moving the membrane to perform a pumping motion, and means for providing a vacuum to the fluid reservoir   applying the vacuum to the fluid reservoir during the second part of a piston stroke of e pump piston during which the membrane unit is emptied from fluid.       
 
         [0087]    Further it is a possible to apply an excess pressure in the fluid reservoir by means of the vacuum piston during a first part of a stroke of the piston element. 
         [0088]    Preferably the membrane pump is a membrane pump as described above. 
         [0089]    A membrane pump with means for applying a vacuum to the fluid reservoir as well as the general use of the vacuum method as described can be used in various pump setups e.g. with or without a regulation chamber as described above. 
         [0090]    Features of the membrane pumps described herein may thus be combined and arguments for similar parts can be valid for the various embodiments. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0091]    The invention will in the following be described in greater detail with reference to the accompanying drawings: 
           [0092]      FIG. 1  a schematic view of a diaphragm pump according to the present invention, 
           [0093]      FIG. 2  is a side view of the membrane pump according to the present invention 
           [0094]      FIG. 3  is a view along the line III-III indicated in  FIG. 2 . 
           [0095]      FIG. 4  is a top view of a diaphragm pump according to the present invention 
           [0096]      FIG. 5  is a view along the line IV-IV indicated in  FIG. 4   
           [0097]      FIG. 6  is a view along the line VI-VI indicated in  FIG. 4  where the secondary piston is advanced 
           [0098]      FIG. 7  is a view from the third side of the diaphragm pump according to the present invention 
           [0099]      FIG. 8  is a view along the line VIII-VIII indicated in  FIG. 4   
           [0100]      FIG. 9  is a side view of a diaphragm pump according to the present invention where the piston is retracted 
           [0101]      FIG. 10  is a side view of a diaphragm pump according to the present invention where the piston is advanced 
           [0102]      FIG. 11  is a view along the VI-VI section indicated in  FIG. 4  where the secondary piston is pushed back 
           [0103]      FIG. 12  is another view from the third side of the diaphragm pump according to the present invention 
           [0104]      FIG. 13   a  and  b  is a view of the third side of the membrane pump and of the end plate 
           [0105]      FIG. 14  is an exploded view of a membrane pump according to the present invention 
           [0106]      FIG. 15  Is another embodiment of a diaphragm pump with means for applying vacuum 
           [0107]      FIG. 16  Is yet another embodiment of a diaphragm pump with means for applying vacuum  FIG. 17   a - c  Illustrates the motion of a diaphragm pump according to  FIGS. 15 and 16 . 
       
    
    
       [0108]    The drawings are exemplary and are not to be construed as limiting to the invention. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0109]      FIG. 1  shows a diaphragm pump  1  according to the present invention. The pump  1  comprises a housing  2  and has a motor  3  attached for driving the pump. The housing  2  is rectangular and thus comprises six surfaces whereof three are seen in  FIG. 1 ; A first side  4  in the present orientation forming the top whereon the motor  3  is attached and outer adjustment means  5  is also located. A second side  6 , in the present orientation forming the front, comprises a removable plate  7 . A third side  8  with an end plate  8   a  is in the present orientation forming an end of the diaphragm pump  1 . The end plate  8   a  of the diaphragm pump  1  is arranged with means  9  for attaching a diaphragm unit (not shown) and means  9   a  for attaching the end plate  8   a  to the housing  2 . 
         [0110]      FIG. 2  shows the diaphragm pump  1  seen from the second side  6 , where the removable plate  7  has been removed revealing a fluid reservoir  10  and a driving means  11  comprising crank  12  and connecting rod  13  driving a piston (not seen) within a piston barrel  14  of a pump element  15  in the fluid reservoir  10 . The piston barrel comprises a number of openings  16  allowing pump fluid (not shown) to pass from the fluid reservoir and into/out of the piston barrel  14  at least when the piston is fully retracted. 
         [0111]      FIG. 3  shows a sectional view taken along the line III-Ill in  FIG. 2 . The figure shows the piston barrel  14 , containing a piston  17  arranged to perform a reciprocating motion along the length direction of the pump housing  2  i.e. parallel to the second side  6 . The piston  17  is driven by the connecting rod  13  which is connected to the crank  12  driven by the driving means  11  and motor  3 . Opposing the pump element  15  also in communication with the driving means is a vacuum pump element  18  having a vacuum piston  19  arranged to reciprocate in a motion parallel to the motion of the piston  17  of the pump element  15 , in a plane slightly shifted compared to the plane of motion of the piston  17 . The motor  3  is arranged in communication with the driving means  11 . In  FIG. 3  adjusting means  5  is also shown here in the form of a secondary piston  21  contained in a secondary piston barrel  22 . The regulating means  5  will be discussed in detail below. 
         [0112]      FIG. 4  shows the diaphragm pump  1  seen from the first side  4 . 
         [0113]      FIG. 5  shows a sectional view taken along the line IV-IV in  FIG. 4 . The section is made to show both the pump element and the vacuum pump element. 
         [0114]    In  FIG. 5  it is schematically indicated how the pump is arranged in relation to a line  23  comprising a fluid F to be pumped by the diaphragm pump  1 . At the third side  8  is arranged a membrane unit  24  having attachment means (not shown) and a membrane  25 . 
         [0115]    In function a pump fluid (not shown) is pumped from the fluid reservoir and/or piston barrel and into the membrane unit during a first part of a stroke of the piston  17  thereby pushing the membrane  25  outwards pressing on the fluid F thereby pumping the fluid F in a specified direction. Depending on the regulation of the adjustment means  5  an amount of pump fluid enters the regulation chamber (not shown) when the piston during the first part of the stroke is pushed forward towards the advanced position, whereby a smaller pressure is put on the membrane  25  and the pump volume is thereby reduced compared to the situation where no pump fluid is allowed to enter the regulation chamber. 
         [0116]    During the second part of the pump stroke fluid is sucked out of the membrane unit and regulation chamber and into the fluid reservoir  10 . 
         [0117]    In  FIG. 5  the piston of the pump element is in its fully retracted position i.e. in the position where pump fluid is sucked out of the membrane unit  24 . Simultaneously the vacuum pump piston  26  is in its fully advanced position thereby creating a volume  27  and thereby sucking pump fluid into the vacuum pump element via a channel opening  28  and channel (not shown) which is in fluid communication with the volume of pump fluid in the fluid reservoir  10 . By pulling pump fluid into the vacuum pump element a vacuum is created in the fluid reservoir  10  which enhance the suction of the pump element  15  helping to empty pump fluid out of the membrane unit  24  and regulation chamber. In  FIG. 5  only outer parts of the adjustment means  5  are shown here in form of a head  29  on a bolt which is used to regulate the active volume of the regulation chamber of the adjustment means  5 . 
         [0118]      FIG. 6  shows a sectional view taken along the line indicated in VI-VI in  FIG. 4  wherein the adjustment means is seen. The adjustment means comprises a regulation chamber  30  formed by a secondary piston barrel  22  wherein the secondary piston  21  can be moved against a bias  31 . A bolt  32  regulates how far back the adjustment piston can be pressed and thereby regulates the active volume of the adjustment means. The active volume is the volume of fluid which can be contained in the regulation chamber thus the active volume depends on how the bolt  32  is adjusted. 
         [0119]    Pump fluid is pressed into, and sucked out of, the regulation chamber  30  via adjustment channel  33 . 
         [0120]      FIG. 7  is a view of the third side of the diaphragm pump  1  where a section A has been cut out to reveal the regulation means  5  and the pump element with piston barrel  14  and piston  17 . 
         [0121]      FIG. 8  shows a sectional view taken along the line VIII-VIII indicated in  FIG. 4 . Here the channel  34  connecting the fluid reservoir (not shown) and the vacuum pump element  18  is clearly seen. As the channel  34  is drilled into the block forming the housing  2  a number of plugs  35  are used to seal the channel openings created by the manufacturing method thus sealing the channel from the surroundings and creating a closed system comprising the fluid reservoir, channel and vacuum pump element. 
         [0122]      FIG. 9  shows the diaphragm pump  1  seen from the second surface with the removable plate removed. Three sections B, C, D have been cut away revealing three different depths of the housing  2 . Section B reveals the piston element  15  in the fluid reservoir  10 . Section C reveals the vacuum pump element. Section D reveals the channel  34 . The relative position of these three cuts are known from e.g.  FIG. 4  where they correspond to the two parts a and b of line IV-IV and line VIII-VIII. 
         [0123]    As in the previous figures the piston is in its fully retracted position and the piston of the vacuum pump element is in its fully advanced position whereby fluid is sucked from the fluid reservoir via the channel and into the vacuum pump element. This means that fluid is withdrawn from the membrane unit and regulation chamber. 
         [0124]      FIG. 10  shows a view of the diaphragm pump as known from  FIG. 9  the difference being that  FIG. 10  shows the situation where the piston  17  is in its fully advanced position and the piston  26  of the vacuum pump element  18  is in its fully retracted position. No fluid can be present in the vacuum pump element  18  and the piston of the pump element has pushed fluid out of the fluid reservoir  10  and inner volume of the piston barrel and into the membrane unit (not shown) and regulation chamber (not shown). The bolt  32  has been adjusted to allow the secondary piston (not shown) to be pushed back to accommodate pump fluid in the active volume of the regulation chamber. 
         [0125]    In this view it is seen that the vacuum pump element comprises vacuum biasing means  37  arranged to push against the piston of the vacuum pump element. 
         [0126]      FIG. 11  corresponds to the view of  FIG. 6  and differs in that the secondary piston has been pushed back by the incoming fluid (not shown) which fills the active volume  38 . If the adjustment means had been set to allow a larger pump volume, the active volume would be smaller. If the adjustment means had been set to allow a smaller pump volume, the active volume would be larger. 
         [0127]      FIG. 12  corresponds to  FIG. 7  but where, as in  FIGS. 11 and 10 , the piston of the adjustment means has been pushed back against the bias. Depending on the force of the secondary bias more or less force from the fluid is needed to press back the secondary piston. By adjusting the secondary bias it is thus possible to adjust how easily the secondary piston is moved by the press of the fluid from the hydraulic camber making it possible to make adjustments e.g. to comply with properties of membrane, fluid and/or fluid to be pumped by the diaphragm pump. 
         [0128]      FIG. 13   a  shows the end plate  8   a  seen from the side abutting the housing  2 .  FIG. 13   b  shows the housing seen from the third side in slight perspective. In this view ( FIG. 13   b ) the piston barrel  14  is seen together with the adjustment channel  33  which is allowing pump fluid to flow between the fluid reservoir  10  with pump element  15  and the regulation chamber (not shown).  FIG. 13   a  shows the inner side  40  of the end plate  8   a  abutting the housing  2  when mounted on the diaphragm pump  1  by means  9   a . The inner side  40  comprises a carving  41  wherein a seal  42  of O-ring type is arranged. The carving  41  is designed to enclose adjustment channel  33  and the end of the piston barrel  14  and is made to avoid leakage pump fluid.  FIG. 13   a  also show outlet  43  through which pump fluid flows into and out of the membrane unit when connected hereto. The outlet  43  is also seen in  FIG. 1  as the central opening in the end plate  8   a.    
         [0129]    Thus during operation the piston  14  is reciprocating in the piston barrel  15  and during each first part of a stroke is pumping pump fluid out of the fluid reservoir and into the adjustment channel  33  from where it can enter the regulation chamber (not shown) if the adjustment means are adjusted to allow this. During second part of the stroke pump fluid is drawn back through the channel  33  and into the fluid reservoir  10 . 
         [0130]      FIG. 14  shows the diaphragm pump in a perspective exploded view. The elements marked with x form part of the driving means. The elements marked with y forms part of the driving motor arrangement. 
         [0131]    In this view the different parts of the diaphragm pump according to the present invention are clearly seen. For example seals  44  and fortified PVDF seals  45  are seen in this figure. 
         [0132]      FIG. 15  shows another embodiment of a diaphragm pump  1  without a mounted membrane unit and regulation chamber. The third side  8  of the diaphragm pump can be arranged to receive an end plate as known from the previous examples or to receive the membrane unit directly. The general features of the membrane pump are known from the previous examples and for same parts same reference numbers are used. In the shown example the piston  17  and vacuum piston  26  are connected end to end and driven by a common driving means  11  with a common connecting rod  13 . For illustrative purposes the two pistons are shown as individual parts connected to be abutting each other, however, the piston  17  and vacuum piston  26  can be formed as a single piece unit. 
         [0133]    The connecting rod  13  is attached to the vacuum piston  26  which vacuum piston is also attached to the piston  17  pumping fluid from the fluid chamber and into a membrane unit if attached. When the connecting rod  13  pushes the vacuum piston  26  forward fluid inside the hollow  46  of the vacuum barrel  47  of the vacuum element  18  is pushed via channel  34  into the fluid reservoir  10  and into the piston barrel  15  if the inlet openings are free. During the same motion of the connecting rod  13  the piston  17  is pushed forward via the vacuum piston in order to pump fluid from pump element and fluid reservoir into a membrane unit (not shown). 
         [0134]    Similarly when the vacuum piston is retracted by the motion of the driving means fluid is drawn from the fluid reservoir  10  through the channels  34  and into the hollow  46  thereby creating a vacuum inside the fluid reservoir  10  enhancing the suction effect of piston  17  during the second part of the piston stroke when the openings  16  are freed when passed by the piston  17 . 
         [0135]    Gasket  48  on vacuum piston  26  ensures that no fluid leaks from the fluid reservoir  10  and hollow  46  and into a space  50  behind the vacuum piston. The space  50  and the volume  51  can be at least partly filled with a fluid. 
         [0136]    The diameter of the vacuum piston  26  and vacuum barrel  47  is larger than the diameters of the piston  17  and piston barrel  14 . 
         [0137]      FIG. 16  shows a system similar to that shown in  FIG. 15 . However in the embodiment in  FIG. 16  the vacuum piston can move relatively to the piston  17 . The degree of relative movement of the two pistons can be limited and/or regulated by stop means  49  in the present example arranged on the piston  17 . 
         [0138]    The relative movement is achieved by allowing the vacuum piston to at least partly to receive the piston  17  thereby allowing a regulation of the pressure/vacuum applied by the vacuum pump element  18 . 
         [0139]      FIG. 17   a - 17   c  shows the movement of the pistons and driving means during part of a piston stroke. 
         [0140]    In  FIG. 17   a  the pistons are in their fully advanced position and the membrane unit is filled with fluid. 
         [0141]    In  FIG. 17   b  the pistons are partly retracted and fluid is drawn into the hollow  36  of the piston barrel while the openings  16  still are closed by the piston  17 . The retraction of the vacuum piston has pulled fluid through channels  34  into the hollow  46  thereby creating a vacuum in the fluid reservoir  10 . 
         [0142]    In  FIG. 17   c  the piston is fully retracted and the openings  16  are now free allowing fluid to flow through the openings  16  into fluid reservoir  10  assisted by the vacuum applied by vacuum piston  26 . 
         [0143]    Thus by the embodiments in  FIGS. 15 ,  16  and  17   a - 17   c  a vacuum is applied to the fluid reservoir by means of the vacuum pump element. Fluid is pumped from the vacuum pump element  18  and into the fluid reservoir  10  through channels  34  and vice versa depending on which part of the piston stroke are carried out. The channels  34  are much shorter in  FIGS. 15 and 16  than in the previous examples but serves the same function i.e. allowing fluid communication between fluid reservoir  10  and vacuum pump element  18 .