Abstract:
The present disclosure relates to a mixing pump ( 10 ) for combining two or more substances. More specifically, the mixing pump ( 10 ) is adapted to combine controlled amounts of those substances so as to produce a mixture containing predetermined proportions of those substances. The mixing pump includes a chamber ( 23 ) lying in fluid communication with a first substance inlet ( 50 ), a second substance inlet ( 51 ) and a mixture outlet ( 52 ). The mixing pump ( 10 ) also includes a pumping member disposed in the chamber ( 23 ) and adapted to draw first and second substances from the first and second substance inlets ( 50,51 ) and to expel a mixture of those substances through the mixture outlet ( 52 ).

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure relates to a pump and more particularly to a pump adapted to combine two or more substances. 
       BACKGROUND 
       [0002]    Some installations consume or use various substances during operation. Some of those substances might need to be combined with other substances immediately prior to use to give them the required characteristics. For example, an engine may be configured to run on diesel or other conventional fuels, but may be adapted also to run on alternative fuels, such as biofuels, kerosene or other military grade fuels. Although those alternative fuels may include sufficient chemical energy for generating the required mechanical energy during combustion, they may lack the lubricity of the more conventional fuels. Many components rely on the natural lubricity of a substance to reduce wear and to enhance operation. For instance, a high-pressure fuel pump may rely on the lubricity of fuel for those same reasons. This shortcoming may be addressed by introducing a minor amount of a lubricant additive to the alternative fuel prior to use. 
         [0003]    Two or more substances may be combined long before use, possibly at the point of preparation or perhaps later at the point of delivery. However, it is probable that the two or more substances may separate prior to use and possibly during storage as the most dense substance may settle towards the bottom of the storage tank. 
         [0004]    Even if the two substances do not fully separate during storage, there is a concern that the homogeneity of the mixture may diminish over time, particularly if the two substances were mixed in an ineffective manner. The precise proportions of the two substances in the mixture may also be critical to the smooth operation of the installation for which the mixture is intended. It may not be practical to assess the proportions of substances in the mixture immediately before consumption so damage to the components may be inevitable and irreparable. 
         [0005]    It is therefore an object of the present disclosure to provide an apparatus that may address the problems outlined above. 
       SUMMARY OF THE INVENTION 
       [0006]    According to the present disclosure, there is provided a pump adapted to combine first and second substances, the pump comprising: a housing; a chamber defined in the housing; a first substance inlet in fluid communication with the chamber; a second substance inlet in fluid communication with the chamber; a mixture outlet in fluid communication with the chamber; and a pumping member disposed at least partially in the chamber and arranged to draw first and second substances from the first and second substance inlets and to expel a mixture of the first and second substances through the mixture outlet. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    By way of example only, one embodiment of the present disclosure will now be described in detail, with reference being made to the accompanying drawings, in which: 
           [0008]      FIG. 1  is a perspective view of a mixing pump according to the present disclosure and mounted to an auxiliary component; 
           [0009]      FIG. 2  is a perspective view of the mixing pump shown in  FIG. 1 , partially disassembled; 
           [0010]      FIG. 3  is a perspective view of the mixing pump shown in  FIGS. 1 and 2 , fully disassembled; 
           [0011]      FIG. 4  is a plan view of a housing forming part of the mixing pump shown in  FIGS. 1 to 3 ; 
           [0012]      FIG. 5  is a plan view of the housing shown in  FIG. 4  with an outer rotor disposed therein; 
           [0013]      FIG. 6  is a plan view of the housing shown in  FIGS. 4 and 5  with the inner and outer rotors disposed therein; 
           [0014]      FIG. 7  is a plan view of the housing shown in  FIGS. 4 to 6 , with the outer rotor arranged in a reference position; 
           [0015]      FIG. 8  is a plan view of the housing shown in  FIGS. 4 to 7 , with the inner and outer rotors both arranged in the reference position; 
           [0016]      FIG. 9  is a plan view of an alternative housing with the outer rotor arranged in a reference position; 
           [0017]      FIG. 10  is a plan view of the alternative housing of  FIG. 9 , with the inner and outer rotors arranged in a reference position; 
           [0018]      FIG. 11  is a plan view of the alternative housing of  FIGS. 9 and 10  with the outer rotor displaced from the reference position; 
           [0019]      FIG. 12  is a plan view of the alternative housing of  FIGS. 9 to 11  with the inner and outer rotors displaced from the reference position; 
           [0020]      FIG. 13  is a cross-section through part of the mixing pump of the present disclosure; 
           [0021]      FIG. 14  is a perspective view of the components shown in  FIG. 13 ; and 
           [0022]      FIG. 15  is a perspective view of the components shown in  FIG. 14  disassembled. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    The following is a detailed description of an exemplary embodiment of the present disclosure. The exemplary embodiment described therein and illustrated in the drawings is intended to teach the principles of the present disclosure, enabling those of ordinary skill in the art to implement and use the present disclosure in many different environments and for many different applications. Therefore, the exemplary embodiment is not intended to be, and should not be considered as, a limiting description of the scope of patent protection. Rather, the scope of patent protection shall be defined by the appended claims. 
         [0024]    Referring initially to  FIGS. 1 to 3 , there is shown a mixing pump  10 , according to the present disclosure. The mixing pump  10  may comprise a linear or rotary pump capable of pressurizing a substance, which may comprise liquid, gaseous or particulate matter. In the present embodiment, the mixing pump  10  may comprise a gerotor, though in an alternative embodiment it may comprise a different rotary pump such as a gear pump, a vane pump, a lobe pump and so on. 
         [0025]    In this particular embodiment, the mixing pump  10  may be mounted to a secondary pump  11  and both, the mixing pump and the secondary pump, may be driven by a common shaft  12  coupled to an engine or alternative drive means, such as an electric motor, via a gear  13 . For instance, the mixing pump  10  may comprise a fuel transfer pump and the secondary pump  11  may comprise a high-pressure fuel pump, which may be integrated into a common housing  14  supporting the common shaft  12  and defining interconnecting passages (not shown). In an alternative embodiment (not shown) of the present disclosure, the mixing pump may be unitary in that it may be separate from any other component and as such it may have its own shaft, its own support means and its own passages. 
         [0026]    The mixing pump  10  may include a mixing pump housing  20  comprising a first part  21  and a second part  22 , which may collectively define a chamber  23 , which may be cylindrical. The first part  21  may define a first sealing face  25 , which may be substantially circular so as to form part of the chamber  23 . In the present embodiment the first part  21  may also define a first mounting face  26  disposed at least partially around the first sealing face  25  for receiving the second part  22 . The first sealing face  25  and the first mounting face  26  may be substantially co-planar and optionally delineated by sealing means, such as an O-ring (not shown). Alternatively, the first sealing face  25  may be spaced behind the first mounting face  26  so as to form a first recess (not shown) having a first peripheral face, which may be substantially circumferential. First fastening means may be associated with the first part  21  and may comprise for example, threaded holes  27  formed in the first mounting face  26  for receiving bolts (not shown) associated with the second part  22 . 
         [0027]    The second part  22  may include a second sealing face  30  which may be substantially circular and an inwardly facing second peripheral face  31  which may be substantially circumferential so as to surround the second sealing face  30 . Collectively the second sealing face  30  and the second peripheral face  31  may define part of the chamber  23 . The second part  22  may also include a second mounting face  33  disposed around the second peripheral face  31  and which is adapted to engage the first mounting face  26  of the first part  21 . As such, the first and second mounting faces  26 , 33  may be correspondingly profiled and orientated. In the present embodiment, each of the first and second mounting faces  26 , 33  and the first and second sealing faces  25 , 30  may be substantially planar and may be arranged parallel to one another. The second part  22  may take the form of a cap furnished with an outwardly extending flange  34  extending at least partway around the outside of the second peripheral face  31 . In the present embodiment the second mounting face  33  may extend entirely around the second peripheral face  31  and may have a generally triangular outline with slightly curved sides, though the outline may take any shape. The outwardly extending flange  34  may be provided with second fastening means arranged to cooperate with the first fastening means of the first housing part. For instance, the second fastening means may include three holes  35 , the first fastening means may include three threaded holes with which the second fastening means align and screws may being arranged to extend into those holes. 
         [0028]    As noted above, the mixing pump  10  may include a shaft  12  adapted for driving connection to an engine or alternative drive means, such as an electric motor. An opening  40  may be formed in one of the first and second sealing faces  25 , 30  for receiving the shaft  12 . The opening  40  may be substantially circular and sized to form a close running fit with the shaft  12 , thus restricting the egress of substance between the opening  40  and the shaft  12 , in use. Furthermore, the centre of the opening  40  may be offset from the centre of the first and second sealing faces  25 , 30  such that the axis of the shaft  12  and the axis of the chamber  23  are not co-axial. The other of the first and second sealing faces  25 , 30  in which the opening  40  is not formed may be provided with a recess  41  arranged opposite the opening  40  so as to receive the free end  42  of the shaft  12 . In the present embodiment, the first sealing face  25  includes the opening  40  and the second sealing face  30  includes the recess  41 , thereby enabling the shaft  12  to extend from the secondary pump  11  and through the opening  40  such that the free end  42  locates in the recess  41 . The shaft  12  may include shaft locking means  44 , such as a slot extending at least partway along its length, which will be discussed in more detail below. The chamber  23  may include a notional reference line R defined by the shortest line extending between the shaft  12  and a point on the second peripheral face  31 . 
         [0029]    The mixing pump  10  may also be provided with a first substance inlet  50 , a second substance inlet  51  and a mixture outlet  52 , all defined within the mixing pump housing  20  and in fluid communication with the chamber  23 . More specifically, the first substance inlet  50 , the second substance inlet  51  and the mixture outlet  52  may be defined in the first sealing face  25 , the second sealing face  30  or a combination of the both. The first substance inlet  50  and the second substance inlet  51  may be formed on one side of the reference line R and the mixture outlet  52  may be formed on the other side of the reference line R. In the present embodiment, the first substance inlet  50  and the mixture outlet  52  may be provided in the first sealing face  25  and the second substance inlet  51  may be defined in the second sealing face  30 , possibly opposite the first substance inlet  50 . 
         [0030]    Depending on the desired proportions of the first and second substances in the mixture, it may be necessary to facilitate a relatively larger flow rate of one of the first and second substances. One method of achieving this is to increase the size of one of the first and second substance inlets  50 , 51 , as required. In the present embodiment, the first substance inlet  50  may serve as a reservoir and may extend some way around one side of the chamber  23 , possibly in an arcuate manner and may even widen as it extends away from the reference line R. The mixture outlet  52  may be correspondingly shaped on the other side of the reference line R. 
         [0031]    Inlet and outlet shallows  55 , 56  may be formed in the second sealing face  30  and which may correspond in size, shape and or location with the first substance inlet  50  and the mixture outlet  52 . These inlet and outlet shallows  55 , 56  may assist in reducing cavitation of the second sealing face  30  as the first substance enters the chamber  23  and the mixture exits the chamber. 
         [0032]    One of the first and second mounting faces  26 , 33  may be furnished with at least one protuberance, such as a pin  58  for location in at least one aperture  59  formed in the other of the first and second mounting faces  26 , 33 . 
         [0033]    The mixing pump  10  may also be furnished with a sealing plate  60  disposed between the first and second parts  21 , 22  so as to overlie the first and second mounting faces  26 , 33 . More specifically the sealing plate  60  may have an outline corresponding to that of the first and second mounting faces  26 , 33  and may include cut-outs  61 , 62 , 63  corresponding substantially to the first substance inlet  50 , the mixture outlet  52  and the at least one protuberance  58 . The sealing plate  60  may serve as a gasket to seal the interface between the first and second parts  21 , 22  of the mixing pump housing  20 . 
         [0034]    In the present embodiment of the disclosure, the second substance inlet  51  may be formed on the second sealing face  30  and may be substantially smaller than the first substance inlet  50 , so as to create a mixture having a greater proportion of first substance than second substance. As noted above, the relative sizes of the first and second substance inlets may be selected according to the first and second substance proportions in the mixture. The second substance inlet  51  is here formed in the second sealing face  30  reasonably close to the reference line R, for reasons discussed below. Referring briefly to a first arrangement shown in  FIG. 4 , the second substance inlet  51  is defined within the inlet shallow  55  and surrounded by a land  65  being generally coplanar to the second sealing surface  30 . In a second arrangement shown in  FIG. 9 , the second substance inlet  51  is located just outside the inlet shallow  55  so as to be disposed a little closer to the reference line R. 
         [0035]    An outer rotor  70  is disposed within the chamber  23  for rotation about the central axis thereof. The outer rotor  70  may be generally annular and may include a circumferential outer face  71 , an undulating inner face  72 , a first side  73  and a second side  74 . The circumferential outer face  71  may be sized to form a close running fit with the second peripheral face  31  of the chamber and the undulating inner face  72  may define a plurality of inwardly facing teeth  75  spaced apart by troughs  76 . The first and second sides  73 , 74  are profiled to correspond to the first and second sealing faces  25 , 30 , respectively, and may be domed, conical or, as with the present embodiment, substantially planar. The clearance between the first sealing face  25  and the first side  73  and the second sealing face  30  and the second side  74  may be selected to form a close running fit. More specifically, the clearance may be selected to enable the outer rotor  70  to rotate within the chamber  23  while restricting the flow of substance between those surfaces. 
         [0036]    The mixing pump  10  may also include an inner rotor  80  which may be carried on the shaft  12  and disposed within the chamber  23  so as to locate within the outer rotor  70 . The inner rotor  80  includes an opening  81  in its centre through which the shaft  12  extends and locking means  82  arranged to prevent relative rotation of the inner rotor  80  and the shaft  12 . The locking means  82  may comprise a slot extending axially along the inner rotor  80  adjacent one side of the opening  81  and which may be aligned with the slot  44  on the shaft  12  so that they may together receive a locking member  84  such as a key to prevent relative rotation of the shaft  12  and the inner rotor  80 . 
         [0037]    The inner rotor  80  has first and second sides  85 , 86  forming a close running fit with the first and second sealing faces  25 , 30  of the chamber  23  and an undulating outer face  87  defining a plurality of outwardly facing teeth  88  and troughs  89 . The number of teeth  88  and troughs  89  on the inner rotor  80  should be selected according to the number of inwardly facing teeth  75  and troughs  76  on the outer rotor  70 , though it should be borne in mind that the inner rotor  80  may include one less tooth  88  and one less trough  89  than the outer rotor  70 . In the present example the inner rotor  80  includes six teeth  88  and six troughs  89  compared to the outer rotor  70  which includes seven teeth  75  and seven troughs  76 . Furthermore, the troughs  89  of the inner rotor  80  and the teeth  75  of the outer rotor may be complementary. In the present embodiment, the teeth  88  of the inner rotor  80  and the troughs  76  of the outer rotor  70  may be complementary and may be substantially the same size and shape. 
         [0038]    The position of the shaft  12  within the chamber  23  is selected having regard to the size and shape of the teeth  88 , 75  and the troughs  89 , 76  of the inner and outer rotors  80 , 70 . In particular, the position of the shaft  12  may be selected so that one tooth  88  of the inner rotor  80  fits snugly inside one trough  76  of the outer rotor  70  when that tooth  88  and that trough  76  locate centrally over the reference line R, see  FIGS. 8 and 10 . The reference line R may be the only location where a tooth  88  of the inner rotor  80  may fit snugly within a trough  76  of the outer rotor  70 . At all other locations the teeth  88  of the inner rotor  80  may fit only partially within the troughs  76  of the outer rotor  70 , thereby defining sub-chambers  90 A- 90 F between the inner and outer rotors  80 , 70 . As the inner and outer rotors  80 , 70  rotate about their respective axes, the size of each sub-chamber  90 A- 90 F increases and decreases as it moves away from and towards the reference line R, respectively. 
         [0039]    It will be appreciated that the position of the second substance inlet  51  can be selected according to the amount of second substance to be dispensed and thus the relative proportions of first and second substances in the resulting mixture expelled through the mixture outlet  52 . More specifically, if the second substance inlet  51  is arranged proximal to the reference line R where the sub-chamber  90 A is at its smallest the opportunity for second substance to be drawn is minimal. Conversely, if the second substance inlet  51  is distal to the reference line where the sub-chamber  90 C is at its largest, the opportunity for second substance to be drawn is maximal. The second substance inlet  51  may be located in a notional circumferential track (not shown) having an outer circumferential boundary defined by the base of each trough  76  of the outer rotor  70  and an inner circumferential boundary defined by the peak of each tooth  75  of the outer rotor  70 . This way, the delivery of second substance into the chamber  23  is always intermittent as the second substance inlet  51  may be alternately opened and closed by the teeth  75  of the outer rotor  70  and, to some extent, the teeth  88  of the inner rotor  80 . The opening time may be greater when the second substance inlet is arranged at a location distal to the reference line R and lesser when arranged at a location proximal to the reference line R. 
         [0040]      FIGS. 13 to 15  disclose an adaptor generally indicated  100  for converting a known pump (such as a gerotor) into a mixing pump  10  according to the present disclosure. The adaptor  100  may comprise a body  101  configured for connection to the pump housing  20 ′ of the gerotor. The body  101  has a mounting face  102  arranged to overlie a second part  22 ′ of the pump housing  20 ′ and an outer periphery  103  corresponding substantially to the outline of the flange  34 ′. The body  101  may include a recess  105  in its mounting face  102  for receiving the second part  22 ′ of the housing of the mixing pump. The recess  105  includes an abutment face  106  arranged to engage sealingly a portion of the second part  22 ′ in which the second substance inlet  51 ′ is formed. To improve the sealing characteristics, the abutment face  106  or the second part  22 ′ may be furnished with a seal member  107 , such as an O-ring arranged to surround the second substance inlet. 
         [0041]    Three openings  108  may be formed in the body  101  and in alignment with the fastening means  35 ′ formed in the second part  22 ′ so as to secure the adaptor  100  to the pump housing  20 ′of the pump  10 ′. 
         [0042]    The adaptor  100  may include a connection portion  110  extending outwardly from the body  101  and which may define a second substance duct  111  arranged to align with the second substance inlet  51 ′ formed in the second part  22 ′. The second substance duct  111  may include a diametrically larger section  112  remote from the abutment face  106  for receiving a second substance supply conduit (not shown). The diametrically larger section  112  may be threaded to receive a threaded connector provided on the end of the conduit. 
       INDUSTRIAL APPLICABILITY 
       [0043]    During manufacturing the mixing pump  10 , the size and positions of the first and second substance inlets  50 , 51  should be selected according to the proportion of first substance and second substance in the mixture. If the mixture is to comprise substantially equal proportions of first and second substances then the size and position of the first and second substance inlets  50 , 51  should be selected so that equally sized areas of those first and second substance inlets  50 , 51  are on average open for equal amounts of time. In the present embodiment, the first substance may comprise a low lubricity fuel, the second substance may comprise a lubricant and the resulting mixture may comprise a high lubricity fuel. Thus, the resulting mixture should include a relatively low proportion of lubricant, by volume, and a high proportion of the low lubricity fuel, by volume. To achieve that proportion, the first substance inlet  50  may be large and may extend across the width of the notional circumferential track. Conversely, the second substance inlet  51  may be small, possibly 0.1 mm 2 , and disposed proximal to the reference line R. The second substance inlet  51  of the first arrangement ( FIGS. 4 to 8 ) and the second substance inlet  51  of the second arrangement ( FIGS. 9 to 12 ) are substantially the same size, though the second substance inlet  51  of the second arrangement is located a little closer to the reference line R, which would result in a lower proportion of second substance in the mixture. 
         [0044]    In the present embodiment, the pressures of the first and second substances are substantially equal at the first and second substance inlets  50 , 51  and thus the proportions of those substances in the resultant mixture may be determined according to the positions and sizes of the first and second inlets. In alternative arrangements, the pressures of the first and second substances may be unequal at the first and second substance inlets  50 , 51 . For example, the pressure of the second substance at the second substance inlet  51  may be substantially lower than the pressure of the first substance at the first substance inlet  50 , thereby reducing the proportion of second substance in the resulting mixture. 
         [0045]    Referring to the first arrangement shown in  FIGS. 4 to 8 , as the shaft  12  and the inner rotor  80  rotate in a clockwise direction about the offset axis of the shaft  12 , its teeth  88  engage the inwardly facing teeth  75  of the outer rotor  70 , which is caused to rotate in the clockwise direction about the central axis of the chamber  23 . The chamber  23  is divided into six sub-chambers: three  90 A- 90 C of which lie in communication with the first substance inlet  50  and draw first substance therefrom; and the other three  90 D- 90 F lie in communication with the mixture outlet  52  and deliver mixture thereto. The six sub-chambers  90 A- 90 F move in the clockwise direction with the inner and outer rotors  80 , 70  and while so doing, the size of each of the sub-chambers  90 A- 90 C in the vicinity of the first substance inlet  50  increases and the size of each of the sub-chambers  90 D- 90 F in the vicinity of the mixture outlet  52  decreases. 
         [0046]    As a new tooth  88  of the inner rotor  80  passes the reference line R a sub-chamber in the vicinity of the mixture outlet  52  disappears and a new sub-chamber in the vicinity of the first substance inlet  50  emerges. In  FIG. 6 , the first sub-chamber  90 A is in fluid communication with both the first substance inlet  50  and the second substance inlet  51  thereby causing first and second substances to be drawn into that sub-chamber  90 A. As the inner and outer rotors  80 , 70  rotate, the sub-chamber  90 A rotates in the clockwise direction and increases in size while maintaining fluid communication only with the first substance inlet  50 , as shown in  FIG. 8 . Incidentally,  FIG. 8  shows the inner and outer rotors  80 , 70  in reference positions whereat one tooth  88  of the inner rotor  80  lies centrally over the reference line R and fits snuggly within a trough  76  of the outer rotor  70 . Sub-chamber  90 A continues to increase in size and to draw more first substance from the first substance inlet  50 . Eventually the sub-chamber  90 A may move around to the mixture outlet  52  whereat it decreases in size and thus expels the mixture of the first and second substances into the mixture outlet  52 . 
         [0047]    The second arrangement shown in  FIGS. 9 to 12  operates in the same manner as the first arrangement shown in  FIGS. 4 to 8 . As noted above, the second substance inlet  51  of the second arrangement is located closer the reference line R so the amount of second substance drawn therefrom is restricted even more. This is because the size of each sub-chamber is always very small in the location of that second substance inlet  51  and as such there is little opportunity for drawing second substance into the sub-chamber  90 A at that location.