Abstract:
Guards for rotary pumps are described, the pump having a main body and further including an impeller housing and a driveshaft extending between the main body of the pump and the impeller housing; the pump further including an adjustable sealing arrangement provided at a region where the driveshaft enters the impeller housing, the guard provides access to adjust the sealing arrangement but obstructs access to the driveshaft.

Description:
TECHNICAL FIELD 
       [0001]    This invention relates to guards used with machines to prevent injury to operators of the machinery. The invention has particular application to rotary pumps. 
       BACKGROUND 
       [0002]    Operators of machines face the risk of injury by coming into contact with moving parts of the machine. For instance, if the hair or clothing of a machine operator were to become entangled with a moving part such as a rotating shaft, then the hair or clothing of the operator may quickly become quickly wrapped around the shaft and the operator can be quickly dragged towards and into contact with moving parts of the machine, which can give rise to very serious injuries. This risk exists during normal operation of the machine and whilst making maintenance inspections or adjustments. 
         [0003]    To reduce the risk of injury to machine operators or maintenance workers, a machine may be fitted with guards which obstruct access to moving parts. This can present an inconvenience to machine operators or maintenance workers, as sometimes it is necessary to remove the guard to carry out routine inspections or maintenance. Unfortunately, it has been found that in practice some guards are sometimes not refitted after removal, and consequently the protection offered by the guard is then lost and the risk of injury during the future operation of the machine is increased. 
         [0004]    Rotary pumps typically comprise a bearing housing and an impeller housing, with a driveshaft extending between the bearing housing and the impeller housing. An adjustable gland seal is provided at the region where the driveshaft enters the impeller housing. The function of the gland seal is to resist escape of pumping medium, such as a slurry or liquid, from the pump whilst allowing for rotation of the driveshaft which supports and drives an impeller located inside the impeller housing. The gland seal is often provided with its own pressurised water supply and some amount of leakage of water or other fluid is normal during operation of the pump. 
         [0005]    The gland seal typically includes some type of packing material which becomes compacted or worn over time. This necessitates regular inspection of the rate of leakage from the gland seal and the making of regular adjustments of the degree of compression applied to the packing material which is typically effected by progressive manual tightening of nuts or bolts which hold a gland follower in compressed relation to the packing material. 
         [0006]    There remains a need for improved guard arrangements for use in association with the region surrounding the driveshaft and gland seal of a rotary pump. 
       SUMMARY 
       [0007]    In a first aspect embodiments are disclosed of a guard for a rotary pump, the pump having a main body and further including an impeller housing and a driveshaft extending between the main body of the pump and the impeller housing; the pump further including an adjustable sealing arrangement provided at a region where the driveshaft enters the impeller housing, the guard provides access to adjust the sealing arrangement but obstructs access to the driveshaft. 
         [0008]    In certain embodiments the adjustable sealing arrangement can include a gland follower and the guard is arranged to be attached to the gland follower. 
         [0009]    In certain embodiments the guard can accommodate changes in the adjustment of the gland follower by way of being formed from at least two guard elements which are arranged to move with respect to one another. 
         [0010]    In certain embodiments the main body of the pump can include a pump base and the guard is further arranged to be attached to the pump base and is arranged to accommodate changes in the distance between the gland follower and the pump base. 
         [0011]    In certain embodiments the main body of the pump includes a bearing housing and the guard is further arranged to be attached to the bearing housing and is arranged to accommodate changes in the distance between the gland follower and the bearing housing 
         [0012]    In certain embodiments the guard can be formed from three guard elements which are arranged to move with respect to one another. 
         [0013]    In certain embodiments the guard elements can be each comprised of two half-shells which fit together. 
         [0014]    In certain embodiments the guard can include apertures to accommodate bolt ends of the adjustable sealing arrangement. 
         [0015]    In certain embodiments the guard can include apertures to allow visual inspection of the sealing arrangement. 
         [0016]    In a second aspect embodiments are disclosed of a rotary pump including a guard according to any one of the preceding claims. 
         [0017]    In a third aspect embodiments are disclosed of a method of retrofitting a guard to a rotary pump including the steps of providing a guard according to the first aspect and installing the guard on the pump. 
         [0018]    In a fourth aspect embodiments are disclosed of a rotary pump, the pump having a main body and further including an impeller housing and a driveshaft extending between the main body of the pump and the impeller housing; the pump further including an adjustable sealing arrangement provided at a region where the driveshaft enters the impeller housing, the adjustable sealing arrangement including a gland seal, an adjustable gland follower and bolt ends projecting from the gland follower; the pump further including a guard, the guard provides access to adjust the sealing arrangement but obstructs access to the driveshaft, the guard includes at least two guard elements, one of the elements is attached to the main body of the pump, the other element is attached to the gland follower, and the guard further including apertures to accommodate the bolt ends of the adjustable sealing arrangement. 
         [0019]    Other aspects, features, and advantages will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, which are a part of this disclosure and which illustrate, by way of example, principles of the inventions disclosed. 
         [0020]    Throughout this specification when the phrase “obstruct access” is used it is intended to mean that the guard is configured to be suitable for blocking the access of a limb, finger, hair or other body part of an operator, or an article of clothing from coming into contact with a moving part of the machine under normal operating conditions. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    An embodiment will now be described, by way of example only, with reference to the accompanying drawings, in which: 
           [0022]      FIG. 1  is a perspective view of the first element of an embodiment of a guard; 
           [0023]      FIG. 2  is a perspective view of the second element of the guard; 
           [0024]      FIG. 3  is a perspective view of the third element of the guard; 
           [0025]      FIG. 4  is a reverse perspective view of the element of  FIG. 3 ; 
           [0026]      FIG. 5  is a perspective view showing the guard installed on a rotary pump; 
           [0027]      FIG. 6  is another perspective view showing the guard installed on the pump; 
           [0028]      FIG. 7  is a cross-sectional view of the arrangement of  FIG. 5  showing the guard in the collapsed configuration; 
           [0029]      FIG. 8  is another cross-sectional view of the arrangement of  FIG. 5  showing the guard in the expanded configuration; 
           [0030]      FIG. 9  is a perspective view of a second embodiment of a guard; 
           [0031]      FIG. 10  is a side view of the upper element of the guard of  FIG. 9 ; 
           [0032]      FIG. 11  is a top view of the upper element of  FIG. 10 ; 
           [0033]      FIG. 12  is a perspective view of the cover piece of the guard of  FIG. 9 ; 
           [0034]      FIG. 13  is a perspective view of the lower element of the guard of  FIG. 9 ; 
           [0035]      FIG. 14  is a perspective view of the guard of  FIG. 9  installed on a rotary pump; 
           [0036]      FIG. 15  is a side cross-sectional view along the mid-line of the guard of  FIG. 9 ; 
           [0037]      FIG. 16  is a perspective view of a third embodiment of a guard; 
           [0038]      FIG. 17  is a rear perspective view of the guard of  FIG. 16 ; and 
           [0039]      FIG. 18  is an exploded view of the guard of  FIG. 16 . 
       
    
    
     DETAILED DESCRIPTION 
       [0040]    It will be convenient to describe the various components of an embodiment of the guard and then show these components assembled together in association with a rotary pump. 
         [0041]    Referring to  FIG. 1 , a first guard element  10  is shown which is formed from two half-shells  14 ,  16 . The first element  10  is arranged to be affixed to the gland follower of an adjustable seal arrangement of a rotary pump by way of inserting bolts through the apertures  13 , to be received in threaded apertures provided in the gland follower. Inspection apertures  15  allow for visual inspection of the seal arrangement through the guard and for escape of liquids. The first element  10  includes an annular recess  17  and a lip  19  which cooperate with a third guard element as will be later described. 
         [0042]    Referring to  FIG. 2 , a second guard element  20  is shown which is formed from two half-shells  24 ,  26 . The second element  20  is arranged to be fitted around the end region of the bearing housing of a rotary pump and is affixed by way of countersunk bolts inserted through the apertures  25 , to be received in threaded apertures in the bearing housing. When the two halves  24 ,  26  are brought together, an opening  27  is created which in use accommodates a grease nipple which is mounted at the upper region of the bearing housing. The second element  20  includes an annular recess  28 , and a flange  29  which cooperate with the third guard element as will be later described. 
         [0043]    Referring to  FIGS. 3 and 4 , a third guard element  30  is shown which is formed from two half-shells  34 ,  36 . The two halves  34 ,  36  are attached together at one side by way of a pivot pin  35 , and at the other side by way of inserting M4 bolts through bolt holes  37  to clamp the halves  34 ,  36  together. The third element  30  includes two apertures  38  which in use accommodate the ends of threaded rods and nuts which form part of an adjustable seal arrangement, as will be later described. Inspection apertures  39  allow for visual inspection of the adjustable seal arrangement through the guard and for the escape of liquids. The third element includes a first lip  33  which cooperates with the annular recess  17  of the first element  10  and a second lip  32  (best seen in  FIG. 4 ) which cooperates with the annular recess  28  of the second element  20  as will be later described. An opening  31  is provided which accommodates the grease nipple. 
         [0044]    Referring to  FIGS. 5 and 6 , the guard  100  formed from the first  10 , second  20  and third  30  guard elements has been installed on a rotary pump in the following manner: 
         [0045]    a) The two halves  14 ,  16  of the first element  10  are attached to respective upper and lower sides of the gland follower  40  by way of inserting bolts (not shown) through the apertures  13 , to be received in the threaded apertures provided in the gland follower  40 . 
         [0046]    b) The two halves  24 ,  26  of the second element  20  are attached to respective left and right sides of the bearing housing  50  by way of inserting countersunk bolts through apertures  25 , to be received in threaded apertures provided in the bearing housing (not visible). 
         [0047]    c) The two halves  34 ,  36  of the third element  30  are joined at one side by way of a pivot pin  35  and are rotated apart. The two halves  34 ,  36  are then offered up and closed together about the first  10  and second  20  elements so that the lip  33  sits in the annular recess  17  of the first element  10  and the lip  32  sits in the annular recess  28  of the second element  20 . M4 bolts are inserted through the bolt holes  37  to clamp the halves  34 ,  36  together and the assembly of the guard  100  is complete. 
         [0048]    Referring to  FIG. 6 , a grease nipple  80  is provided on the bearing housing. This is accommodated by openings  27 ,  31 . 
         [0049]    Referring again to  FIG. 5 , the guard  100  allows visual inspection of the gland seal through inspection apertures  15 ,  39  whilst at the same time obstructing access to the driveshaft  70  (visible in  FIG. 7 ) to prevent injury to the pump operator. Furthermore, it can be seen that the nuts  42 , which are mounted on the threaded rods  44 , which are used to adjust the compression applied by the gland follower  40  of the gland seal, remain accessible for adjustment with a spanner or the like whilst the guard is installed on the pump. Therefore, the gland seal can be adjusted without the need to remove the guard  100  or shut down the pump. 
         [0050]    In  FIG. 5 , one nut  42  is visible. Another identical nut  42  and a threaded rod  44  are provided on the hidden side of the gland follower  40 . The ends of the threaded rods  44  and, to some extent, the nuts  42  are accommodated in the recesses  38 . 
         [0051]    Over a period of time, the distance between the gland follower and the bearing housing gradually increases as the packing material is worn away and the nuts  42  holding the gland follower  40  are progressively tightened. Movement of the gland follower by a distance of about 2 to 4 centimetres over time is not unusual. Furthermore, this distance may also change if the position of the impeller in the housing is adjusted by way of lateral adjustment of the position of the driveshaft with respect to the bearing housing, or adjustment of the position of the impeller housing with respect to the driveshaft, depending upon the configuration of the pump. Such adjustments may be made as a result of wear of the impeller, or in the event of replacement of an impeller, to provide appropriate clearance between the face of the impeller and the inner surface of the impeller housing to achieve optimum pumping performance. The guard  100  accommodates such changes in distance by way of being able to move in a telescopic fashion as will now be described. 
         [0052]    Referring to  FIG. 7 , it can be seen that lip  32  of the third element  30  is sitting to the left-hand side (as depicted in the figure) of the annular recess  28  of the second element  20 , and the lip  33  of third element  30  is sitting to the right-hand side of the annular recess  17  of first element  10 . The guard  100  is thus in a collapsed configuration as would be the case if the packing material in the gland seal had been recently replaced. The freedom of movement of the third element  30  with respect to the second element  20  in the collapsed configuration is limited by the lip  21 , thus ensuring adequate clearance between the inside face of the third element  30  and the rotating driveshaft  70  assembly. 
         [0053]    Over time, gland follower  40  will move progressively in a direction to the right as shown in the drawing as the packing material is compacted and worn, and the gland follower nuts  42  are progressively tightened. 
         [0054]    Referring to  FIG. 8 , in this depiction the pump has been in operation for a period of time and adjustments have been made to progressively tighten the gland follower nuts  42 . It can be seen that the lip  32  of third element  30  has moved to the right-hand side of the annular recess  28  of the second element  20  and the lip  33  of the third element  30  has moved to the left-hand side of the annular recess  17  of the first element  10 . The guard  100  is now in an expanded configuration. 
         [0055]    The third element  30  can be said to “float” with respect to the first  10  and second  20  elements. The third element  30  is retained in associated with the first  10  and second  20  elements by way of the cooperation of the lip  33  with the lip  19  of the first element, and by cooperation of the lip  32  with the flange  29  of the second element. The guard  100  obstructs access to the driveshaft by a pump operator over the entire range of relative movement of the guard elements  10 ,  20  and  30 . 
         [0056]    Referring to  FIGS. 9 to 15 , an alternative embodiment of a guard is shown. The guard  200  is comprised of an upper element  110 , a lower element  120  and a cover piece  140 . 
         [0057]    The upper element  110  is arranged to be affixed to the gland follower of a rotary pump by way of inserting bolts though the apertures  113  in a similar manner as to the first described embodiment hereinbefore. Referring to  FIG. 10 , inspection apertures  115  allow for a visual inspection of the seal arrangement of the pump through the guard as well as for the escape of liquids. In use, two apertures  118  accommodate the ends of threaded rods which form part of an adjustable seal arrangement in a somewhat similar fashion as to the first described embodiment. 
         [0058]    Referring to  FIG. 11 , the upper element  110  includes a recess  131  which accommodates a grease nipple when the guard  200  is fitted to a pump. 
         [0059]    Referring to  FIG. 12 , a cover piece  140  affixes to the bearing housing of a pump in use and is a sliding fit inside a recess  131  of upper element  110 . A bracket  140  is affixed to the bearing housing of a pump by way of the grease nipple of the pump. 
         [0060]    The stem of the grease nipple is inserted through aperture  142  and tightened to secure the cover plate  140  between the base of the grease nipple and the outer surface of the bearing housing of the pump. A tongue portion  144  sits inside the recess  131  and thus obstructs access to the sealing arrangement through the recess  131 . 
         [0061]    Referring to  FIG. 13 , the lower element  120  includes tabs with apertures  122  for affixing to the base of the rotary pump. Inspection apertures  129  allow for inspection of the sealing arrangement from below when the guard  200  is affixed to the rotary pump. 
         [0062]    Referring to  FIG. 14 , the guard  200  is shown affixed to a rotary pump which includes a bearing housing  50  and a pump base  60 . As was the case for the first described embodiment hereinabove, the gland seal of the pump is adjusted by way of adjusting nuts  42 . The ends of threaded rods  44  are accommodated in the apertures  118 . 
         [0063]    Referring to  FIG. 15 , the upper portion  110  moves along with the gland follower of the pump, whereas lower portion  120  is affixed to the pump base. As the gland seal is adjusted, the upper  110  and lower  120  elements move in relation to one another to thereby accommodate changes in the distance between the gland follower and the pump base. At all times, nuts  42  are accessible for adjustment by way of a spanner or the like. 
         [0064]    Furthermore, as the upper element  110  moves with respect to bearing housing  50 , aperture  131  in upper portion  110  remains obstructed by bracket  140 . In this way, the cover plate  140  serves to accommodate changes in the distance between the gland follower and the bearing housing. 
         [0065]    Referring to  FIGS. 16 to 18 , a third embodiment of a guard  300  is shown including an upper element  310 , a lower element  320  and a cover piece  340 . This embodiment differs from the second embodiment of  FIGS. 9 to 15  in that only two apertures  313  are provided for affixing the upper element  310  to the gland follower. Furthermore, the lower element  320  has a “V” shaped profile, rather than a semi-circular profile. 
         [0066]    As best seen in  FIG. 18 , the upper element  310  includes flap portions  319  which overlap with the side portions of the lower element  320 . The flap portions  319  help to avoid a gap opening up between the guard elements  310 ,  320  as they move in relation to one another to obstruct access through the guard. 
         [0067]    The operation of the third embodiment is otherwise similar to the second described embodiment with the upper element  310  moving with the gland seal and the lower element  320  being affixed to the pump base. 
         [0068]    The various guard element components described above may be formed by stamping a flat sheet of mild steel and painted, for example. 
         [0069]    It can be seen that embodiments of the invention have at least one of the following advantages:
       Adjustment of a gland seal may be made without the need to remove the pump guard or the need to stop the pump.   The guard adjusts to accommodate operational adjustments made to the pump.   Inspection apertures allow for visual inspection of the gland seal and also allow for escape of liquid from the region of the gland seal.       
 
         [0073]    Any reference to prior art contained herein is not to be taken as an admission that the information is common general knowledge, unless otherwise indicated. 
         [0074]    In the foregoing description of certain embodiments, specific terminology has been resorted to for the sake of clarity. However, the disclosure is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes other technical equivalents which operate in a similar manner to accomplish a similar technical purpose. Terms such as “left” and right”, “front” and “rear”, “above” and “below” and the like are used as words of convenience to provide reference points and are not to be construed as limiting terms. 
         [0075]    In this specification, the word “comprising” is to be understood in its “open” sense, that is, in the sense of “including”, and thus not limited to its “closed” sense, that is the sense of “consisting only of”. A corresponding meaning is to be attributed to the corresponding words “comprise”, “comprised” and “comprises” where they appear. 
         [0076]    In addition, the foregoing describes only some embodiments of the invention(s), and alterations, modifications, additions and/or changes can be made thereto without departing from the scope and spirit of the disclosed embodiments, the embodiments being illustrative and not restrictive. 
         [0077]    Furthermore, invention(s) have been described in connection with what are presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention(s). Also, the various embodiments described above may be implemented in conjunction with other embodiments, e.g., aspects of one embodiment may be combined with aspects of another embodiment to realize yet other embodiments. Further, each independent feature or component of any given assembly may constitute an additional embodiment.