Patent Publication Number: US-10767813-B2

Title: Lubricant injector

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to lubrication systems, and more particularly to lubricant injectors used in lubrication systems. 
     Lubricant injectors are known and typically include a body connectable to source of lubricant and an outlet connected to a point of delivery of lubricant, such as for example, a bearing. A piston is disposed within the body and functions to draw lubricant into the body and then dispense the lubricant through the outlet. Various passages and one or more valves within the injector body direct lubricant flow in a desired manner through the body. 
     SUMMARY OF THE INVENTION 
     In one aspect, the present invention is a lubricant injector for delivering a predetermined quantity of lubricant, the injector comprising a body having opposing first and second ends and a longitudinal axis extending between the two ends. The body includes an inlet at the body first end fluidly coupleable to a source of lubricant, an outlet, and an elongated bore extending generally along the body axis and having an outer end at least proximal to the body second end, a closed inner end spaced axially from the body first end, a first port, and a second port disposed generally axially between the bore closed end and the first port. A delivery chamber is separate from the bore and having an inlet port and an outlet port fluidly coupled with the body outlet. Further, a piston is disposed within the elongated bore so as to divide the bore into an operating chamber fluidly coupled with the first port and a measuring chamber fluidly coupled with the second port. The operating chamber is fluidly coupled with the inlet and the measuring chamber is located axially between the bore closed end and the operating chamber and is fluidly coupleable with the inlet and alternatively with the delivery chamber. 
     In another aspect, the present invention is again a lubricant injector for delivering a predetermined quantity of lubricant, the injector comprising a body having opposing first and second ends and a longitudinal axis extending between the two ends. The body includes an inlet at the body first end fluidly coupleable to a source of lubricant, an outlet, and an elongated bore extending generally along the body axis and having an outer end at least proximal to the body second end, a closed inner end spaced axially from the body first end, a first port, and a second port disposed generally axially between the bore closed end and the first port. A delivery chamber is separate from the bore and having an inlet port and an outlet port fluidly coupled with the body outlet. An operating chamber passage extends between and fluidly connects the body inlet and the first port of the elongated bore, a valve passage extends between and fluidly connects the body inlet and the inlet port of the delivery chamber and a measuring chamber passage extends between and fluidly connects the second port of the elongated bore with the valve passage. Further, a piston is disposed within the elongated bore so as to divide the bore into an operating chamber fluidly coupled with the first port and a measuring chamber fluidly coupled with the second port. The operating chamber is fluidly coupled with the inlet and the measuring chamber is located axially between the bore closed end and the operating chamber and is fluidly coupleable with the inlet and alternatively with the delivery chamber. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The foregoing summary, as well as the detailed description of the preferred embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings, which are diagrammatic, embodiments that are presently preferred. It should be understood, however, that the present invention is not limited to the precise arrangements and instrumentalities shown. In the drawings: 
         FIG. 1  is an axial cross-section of a lubricant injector in accordance with the present invention; 
         FIG. 2  is a diagrammatic view of an exemplary lubrication system incorporating the injector; 
         FIG. 3  is a front elevational view of the injector; 
         FIG. 4  is an axial cross-sectional view through line  4 - 4  of  FIG. 3 ; 
         FIG. 5  is a perspective view of a plurality of the injectors on a lubrication manifold; 
         FIG. 6  is a broken-away, enlarged view of a portion of  FIG. 1 , showing a piston in an initial position; 
         FIG. 7  is another view of the injector portion shown in  FIG. 6 , depicting the piston in a maximum volume position; 
         FIG. 8  is an axial cross-sectional view of the piston and a rod; 
         FIG. 9  is an broken-away, enlarged view of a portion of  FIG. 8 ; 
         FIG. 10  is partly broken-away axial cross-sectional view of the injector body shown without the piston, rod and a valve; 
         FIG. 11  is a broken-away, axial cross-sectional view of a lower portion of the injector, showing the valve member in a valve first position; 
         FIG. 12  is another view of the injector portion shown in  FIG. 11 , depicting the valve member in a valve second position; 
         FIG. 13  is an axial cross-sectional view of a valve member and guide member; 
         FIG. 14  is an axial cross-sectional view of an insert providing a valve passage and a delivery chamber inlet port; 
         FIG. 15  is a broken-away, axial cross-sectional view of the injector showing a plug member and an adjustment member for establishing a predetermined volume of the measuring chamber; 
         FIG. 16  is a broken-away, axial cross-sectional view of a top portion of the injector assembly including the piston, rod and the plug and adjustment member assembly, showing the adjustment member in a position to establish a maximum volume of the measuring chamber; 
         FIG. 17  is another view of the injector portion shown in  FIG. 12 , depicting the adjustment member in a position to establish a minimum volume of the measuring chamber; and 
         FIGS. 18A-18D , collectively  FIG. 18 , are each an axial cross-sectional view of the injector each depicting a separate one of four stages of operation of the injector. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Certain terminology is used in the following description for convenience only and is not limiting. The words “inner”, “inwardly” and “outer”, “outwardly” refer to directions toward and away from, respectively, a designated centerline or a geometric center of an element being described, the particular meaning being readily apparent from the context of the description. Further, as used herein, the words “connected” and “coupled” are each intended to include direct connections between two members without any other members interposed therebetween and indirect connections between members in which one or more other members are interposed therebetween. The terminology includes the words specifically mentioned above, derivatives thereof, and words of similar import. 
     Referring now to the drawings in detail, wherein like numbers are used to indicate like elements throughout, there is shown in  FIGS. 1-18  a lubricant injector  10  for delivering a predetermined quantity of lubricant, preferably grease, to a delivery point PD such as a bearing  1  or other device to be lubricated. The injector  10  is a component of a lubrication system  2  including a lubricant supply  3 , a pump  4  for pressurizing the lubricant, and a plurality of fluid supply lines  5  and delivery lines  6 , such as hoses, pipes, etc., as shown in  FIG. 2 . The injector  10  comprises a body  12  having opposing first and second ends  12   a ,  12   b  and a longitudinal axis A L  extending generally between the two ends  12   a ,  12   b . The body  12  is preferably generally elongated along the axis A L , as depicted in  FIGS. 1-5, 10 and 18  and described in further detail below, but may be generally “blocky” or compact (e.g., generally rectangular, etc.). In any case, the body  12  includes an inlet  14  fluidly coupleable to the source of lubricant  3 , the inlet  14  preferably extending through the body first end  12   a , and at least one and preferably two outlets  16 , which each preferably extend through a sidewall  13  between the body ends  12   a ,  12   b . Typically, only one outlet  16  is used for a particular application and the other one is plugged (not shown) although both outlets  16  may be used in certain applications. Further, the body  12  includes an elongated bore  18  extending generally along the body axis A L  and having an outer end  18   a  located at, and preferably extending through, the body second end  12   b  and a closed inner end  18   b  spaced axially from the body first end  12   a . The bore  18  has a first port  20  and a second port  22  disposed generally axially between the bore closed end  18   b  and the first port  20 . 
     Referring to  FIGS. 6, 7 and 10 , the bore  18  is preferably at least partially defined by a substantially circular cylindrical, inner circumferential surface  19  having an inside diameter ID B  with a substantially constant value along the axis A L , such that at least a section of the bore  18  has a constant size between the ends  18   a ,  18   b . Additionally, the bore  18  preferably has a counterbore threaded section  18   c  located adjacent to the outer end  18   a , which is engageable by a plug  80  as described below. 
     Referring now to  FIGS. 1, 4, and 10 , the injector body  12  further has a delivery chamber  24  separate from the bore  18  and having an inlet port  26  and at least one and preferably two outlet ports  28  each fluidly coupled with a separate body outlet  16 . The delivery chamber  24  is preferably formed as a generally circular cylindrical bore  25  extending generally along the axis A L  and having an outer end  25   a  providing the inlet and a closed inner end  25   b , as indicated in  FIG. 10 . The delivery chamber  24  is preferably disposed axially between the body first end  12   a  and the elongated bore  18 , but may alternatively be disposed generally between the bore  18  and the sidewall  13 . 
     As shown in  FIGS. 1, 4, 6, 7, 16 and 17 , the injector  10  further comprises a piston  30  disposed within the elongated bore  18  so as to divide the bore  18  into an operating chamber  32  and a measuring chamber  34 . The operating chamber  32  is fluidly coupled with the first port  20 , and thereby to the body inlet  14  as discussed below, and is used to operate the piston  30 , as described in detail hereafter. The measuring chamber  34  is located axially between the bore inner end  18   b  and the operating chamber  32  and is fluidly coupled with the bore second port  22 , so as to be fluidly coupleable with the injector inlet  14  and alternatively with the delivery chamber  24 , as discussed in further detail. 
     Referring to  FIGS. 8 and 9 , the piston  30  includes a generally circular cylindrical body  36  having opposing first and second axial ends  36   a ,  36   b  and an outer circumferential surface  33  extending axially between the ends  36   a ,  36   b  and slidably disposed against the bore inner surface  19 . The outer surface  33  has an outside diameter OD P  ( FIG. 8 ) having a generally constant value between the first and second axial ends  36   a ,  36   b , which is preferably slightly lesser than the value of the bore inside diameter ID B  such that the piston  30  is slidably displaceable within the bore  18 , although the piston  30  preferably has an inwardly offset surface section  44  adjacent to the body first end  36   a  and spaced inwardly from the bore inner surface  19 . Further, a rod  35  is connected with the piston  30  and extends generally axially from the piston second axial end  36   b  and through the operating chamber  34 . Preferably, the rod  35  has a first end  35   a  disposed within a through-bore  31  of the piston  30 , but may alternatively be disposed within a blind hole of the piston or attached to the piston second end  36   b  (neither alternative shown). Further, the rod  35  has a generally circular outer surface  37  providing a rod outer perimeter OP R  and has an outside diameter OD R  ( FIG. 9 ). 
     Furthermore, the piston  30  has a first, substantially circular radial pressure surface  40  on the body first axial end  36   a  and a second, generally annular radial pressure surface  42  on the body second axial end  36   b . The circular cylindrical outer circumferential surface  33  extends between the axial ends  36   a ,  36   b  and defines an outer perimeter P P  of the piston  30 . Preferably, a generally annular groove  45  extends radially-inwardly from the piston outer surface  44  and an annular sealing member  46 , for example, an O-ring, is disposed within the groove  45  so as to seal between the piston  30  and the bore  18 . Further, the radial pressure surface  40 , which is partially provided by an end surface  35   b  of the rod  35 , extends to the piston outer perimeter P P  and partially bounds the measuring chamber  34 , i.e., along with the bore inner end  18   b  and a portion of the bore inner surface  19 , and has a first surface area SA 1 . The second, annular pressure surface  42  is defined between the rod outer perimeter P R  and the piston outer perimeter OP P  and partially bounds the operating chamber  32 , along with a portion of the bore inner surface  19 , and has a second surface area SA 2 . 
     Referring to  FIGS. 6, 7 and 9 , the piston  30  is axially displaceable solely by a differential between a first force F 1  generated by lubricant pressure exerted on the first pressure surface  40  and a second force generated F 2  by lubricant pressure exerted on the second pressure surface  42 , as indicated in  FIG. 9 . That is, the piston  30  is displaceable in a first direction D 1  along the axis A L  and alternatively displaceable in a second direction D 2  along the axis by differentials between the lubricant pressures in the two chambers  32 ,  34  and without the need for assistance from springs or other devices. When lubricant pressure in the measuring chamber  34  is sufficiently high in comparison with pressure in the operating chamber  32 , the piston  30  displaces in the first direction D 1  from a piston initial position PP I  and the volume of the measuring chamber  34  increases while the volume of the operating chamber  32  correspondingly decreases until reaching a piston maximum position PP M  (i.e., maximum measuring chamber volume). Likewise, when lubricant pressure in the operating chamber  32  is sufficiently high in comparison with pressure in the measuring chamber  34 , the piston  30  displaces in the second direction D 2  from the piston maximum position PP M  and the volume of the operating chamber  32  increases while the volume of the measuring chamber  34  correspondingly decreases until reaching the initial position PP I . 
     Referring to  FIGS. 8 and 9 , the rod  35  is preferably sized such that a ratio between the rod outside diameter OD R , and thus the rod outer perimeter P R , at the piston second end  30   b  and the piston outside diameter OD P  is at least 0.5, and preferably within a range of about 0.5 and about 0.7. As such, the relative sizing of the rod  35  and the piston  30  provides a desired ratio between the second pressure surface area SA 2  and the first pressure surface area SA 1 , which provides a desired responsiveness of the injector  10  as discussed in further detail below. 
     Referring specifically to  FIG. 8 , the rod  35  is preferably formed of two-piece construction and includes a first, diametrically-larger rod section  39  and a second, diametrically-smaller rod section  41 . The first rod section  39  has a first end  39   a  attached to, and preferably disposed within, the piston  30  and an opposing second end  39   b  with a generally radial engagement surface  43 , the first rod section  39  providing the rod outer perimeter OP R  at the piston second axial end  30   b , as described above. The second, diametrically-smaller rod section  41  is attached to the second end  39   b  of the first rod section  39  and extends through an adjustment member  86 , as described below. Alternatively, the rod  35  may be formed of one-piece construction and having a constant or tapering outer diameter OD R , or may be formed of three or more rod sections of any appropriate relative sizing (no alternatives shown). 
     Referring now to  FIGS. 1 and 10-12 , the injector body  12  further includes an operating chamber passage  50  for transporting lubricant to and from the operating chamber  32 , a measuring chamber passage  52  for transporting lubricant to and from the measuring chamber  34 , and a valve passage  54  for coupling the measuring chamber passage  52  with the body  14  inlet and alternately with the delivery chamber  24 . Specifically, the operating chamber passage  52  extends between and fluidly connects the body inlet  14  and the first port  20  of the elongated bore  18 , and thereby the inlet  14  with the operating chamber  32 . The measuring chamber passage  52  extends between and fluidly connects the second port  22  of the elongated bore  18  with the valve passage  54 , and thus connects the measuring chamber  34  with the valve passage  54 . Further, the valve passage  54  extends between and fluidly connects the body inlet  14  and the inlet port  26  of the delivery chamber  24 , and thereby couples the measuring chamber passage  52  with the inlet  14  and the inlet port  26 . 
     Furthermore, the inlet  14  preferably includes an inlet chamber  56  extending inwardly from the body first end  12   b , with each of the operating chamber passage  50  and the valve passage  54  having a first end  50   a ,  54   a , respectively, connected with the chamber  56 . Thereby, the two passages  50 ,  54  are fluidly connected through the inlet chamber  56 . The operating chamber passage  50  extends from the first end  50   a  at the inlet chamber  56  to a second end  50   b  at the bore first port  20 , such that the passage  50  fluidly connects the body inlet  14  and the first port  20  of the elongated bore  18 . Thus, lubricant flows from the inlet  14 , through the operating chamber passage  50  and into the operating chamber  32  and alternatively flows from the operating chamber  32 , through the operating chamber passage  50  and the inlet chamber  56 , and into the valve passage  54 . 
     The valve passage  54  extends between the first end  54   a  at the inlet chamber  56  and a second end  54   b  at the delivery chamber inlet port  26 , with a first end  52   a  of the measuring chamber passage  52  being connected to a central portion of the valve passage  54 . As such, the second port  22  of the elongated bore  18  is connected with the body inlet  14  through the measuring chamber passage  52  and a first portion  55 A of the valve passage  54  and alternatively to the delivery chamber inlet port  26  through the measuring chamber passage  52  and a second portion  55 B of the valve passage  54 . With this structure, lubricant flows from the inlet chamber  56 , either from externally of the body  12  or from the operating chamber  32 , through the valve passage first portion  55 A and the measuring chamber passage  52 , and into the measuring chamber  34 . Alternatively, lubricant flows from the measuring chamber  34 , through the measuring chamber passage  52  and the valve passage second portion  55 B, and into the delivery chamber  24 . 
     Referring to  FIGS. 1 and 11-13 , in order to regulate the flow of lubricant between the three passages  50 ,  52  and  54 , the injector  10  further comprises a valve member  60  disposed within the valve passage  54 . The valve member  60  is movable between a first position VP 1  ( FIG. 11 ), in which the body inlet  14  is fluidly coupled with the measuring chamber  34  through the measuring chamber passage  52 , and a second position VP 2  ( FIG. 12 ) in which the measuring chamber  34  is fluidly coupled with the delivery chamber  24  through the measuring chamber passage  52  and the valve passage  54 . Preferably, the valve  60  includes a generally cylindrical, substantially solid body  62  linearly displaceable along the valve axis A V  between the first and second positions VP 1 , VP 2 . The body  62  having an outer circumferential surface  63  and an annular groove  64  extending radially inwardly from the outer surface  63 , the groove  64  generally dividing the body  62  into first and second plug sections  66 A,  66 B. 
     With the above structure, when the valve member  60  is at the first position VP 1 , as depicted in  FIGS. 4 and 11 , the valve groove  64  fluidly connects the measuring chamber passage  52  with the body inlet  14  while the first plug section  66 A obstructs the delivery chamber inlet port  26 . In this valve position, lubricant flows from the inlet  14  and/or the operating chamber  32 , through the valve groove  64  and the measuring chamber passage  52  and into the measuring chamber  34 . Alternatively, when the valve member  60  is at the second position VP 2 , as shown in  FIGS. 1 and 12 , the valve groove  64  fluidly connects the measuring chamber passage  52  with the delivery chamber inlet port  26  while the second plug portion  66 B substantially obstructs the valve passage inlet  54   a . As such, in the second valve position VP 2 , lubricant flows from the measuring chamber  34 , through the measuring chamber passage  52  and the valve groove  64  and into the delivery chamber  24 . 
     Referring to  FIGS. 1, 4 and 11-13 , the valve member  60  preferably further includes a guide rod  68  extending into the delivery chamber  24  and the injector  10  further comprises at least one and preferably two biasing members  70  disposed about the guide rod  68  and configured to bias the valve member  60  toward the valve first position VP 1 . More specifically, the guide rod  68  has a lower circular flange portion  69  at a first end  68   a  proximal to the delivery chamber inlet  14 , a bore  72  extending inwardly from the first end  68   a  and an opposing second end  68   b  spaced from the chamber inlet port  26 . A portion of the first plug section  66 A is disposed within the guide rod bore  72  to attach the rod  68  to the cylindrical body  62 . Further, the guide rod second end  68   b  is contactable with the delivery chamber closed end  25   b  so as to prevent further valve displacement in the first direction D 1  along the valve axis A V , the rod length (not indicated) being selected to position the valve member  60  at the valve second position VP 2  when the rod end  68   b  contacts the chamber end  25   b , as depicted in  FIG. 1 . 
     Additionally, the two preferred biasing members  70  are preferably an inner, relatively smaller-diameter coil compression spring  74  disposed about the guide rod  68  and an outer, relatively larger-diameter coil spring  75  disposed about the inner spring  74 . Each coil spring  74 ,  75  has a first end  74   a ,  75   a  disposed against the guide rod flange section  69  and a second end  74   b ,  75   b  disposed against a closed end  25   b  of the delivery chamber  24 . As such, movement of the valve member  60  toward the valve second position VP 2  compresses the springs  74 ,  75  between the guide flange portion  70  and the delivery chamber closed end  25   b , generating a biasing force F B  that displaces the valve member  60  back toward the valve first position VP 1  when lubricant pressure on the valve body  62  decreases below a certain value. 
     Referring to  FIGS. 1 and 15-17 , the injector  10  preferably comprises a generally cylindrical plug  80  with a central bore  81 , which is at least partially threaded, and is coupled with the body second end  12   b  so as to generally enclose the outer end  18   a  of the body elongated bore  18 . The plug  80  preferably has a radially-outwardly extending shoulder  82  and a lower threaded portion  83  threadedly engaged with a threaded section  18   c  of the body elongated bore  18 . The plug  80  is mounted to the body  12  by advancing the plug threaded section  83  along the bore threaded section  18   c  until the shoulder  82  contacts the second end  12   b  of the body  12 . Further, a generally annular seal  84  is coupled with an inner end  80   a  of the plug  80 , most preferably disposed within a counterbore  85  of the plug  80 , and is configured to seal between the rod first section  39  and the plug  80 . Thus, the seal  84  prevents lubricant leakage through the bore outer end  18   a  and out of the body second end  12   b.    
     Further, a generally tubular adjustment member  86  is disposed at least partially within the plug bore  81  and has opposing axial ends  86   a ,  86   b  and a central through-hole  87  extending between the ends  86   a ,  86   b . The inner axial end  86   a  provides a generally radial stop surface  88  and the adjustment member  86  is adjustably positionable within the plug bore  81  so as to vary an axial position of the stop surface  88 . Preferably, at least a portion of the adjustment member outer surface  86   c  is threaded and is threadedly engaged with the plug bore  81 , such that rotation of the adjustment member  86  varies the axial position of the stop surface  88 , but the adjustment member  86  may be otherwise adjustably positionable within the plug  80  (e.g., by projections and grooves, detents, etc.). Furthermore, a cap  89  has an open end  89   a  engageable about the outer end  80   b  of the plug  80  and functions to enclose the outer ends  80   b ,  86   b  of the plug  80  and the adjustment member  86 , respectively. 
     With the plug and adjustment member assembly, the rod second section  41  is preferably disposed within the adjusting member through-hole  87 , such that the rod section  41  axially displaces within the member  86  when the piston  30  displaces within the bore  18 . The rod engagement surface  43  is contactable with the adjusting member stop surface  88  so as to limit axial displacement of the piston  30  in the first direction D 1  along the central axis A L , as shown in  FIG. 17 . Thereby, the position of the adjustment member stop surface  88  establishes a desired volume of the measuring chamber  34  between a minimum value when the stop surface  88  is at a most proximal position to the plug inner end  80   a  ( FIG. 17 ) and a maximum value when the stop surface  88  is located at a most distal position from the plug inner end  80   a  ( FIG. 16 ). More specifically, displacement of the adjustment member  86  in the second axial direction D 2  toward the plug inner end  80   a  decreases the potential volume of the measuring chamber  34 , thereby decreasing the volume of the lubricant delivered by the injector  10  as discussed in detail below. Conversely, displacement of the adjustment member  86  in the first axial direction D 1  away from the plug inner end  80   a  increases the potential volume of the measuring chamber  34 , thereby increasing the volume of the lubricant delivered by the injector  10 . 
     Referring to  FIGS. 1, 4 and 10 , the injector body  12  is preferably formed of two-piece construction including a base member  90  providing the body first end  12   a  and a main body section  92  extending to the body second end  12   b . The base section  90  is generally rectangular, has opposing axial ends  90   a ,  90   b  and provides the body inlet  14  and inlet chamber  56 , a first section  51 A of the operating chamber passage  50 , a first section  53 A of the measuring chamber passage  52 , the valve passage  54  and the inlet chamber  56 . The main body section  92  has opposing first and second ends  92   a ,  92   b , is generally elongated and extends along the longitudinal axis A L , and most preferably has generally rectangular radial cross sections through the axis A L , but may alternatively be generally circular cylindrical, generally hexagonal or any other appropriate shape as desired. The main body section  92  provides the elongated bore  18 , the delivery chamber  24 , a second section  51 B of the operating chamber passage  50  and a second portion  53 B of the measuring chamber passage  52 . The main body first end  92   a  is attached to the base section second end  90   b  to form an interface  95  and two sealing members  96 , preferably O-rings, are provided within the interface to seal about the fluid connections between the operating and measuring chamber passage sections  51 A,  51 B and  53 A,  53 B of the operating and measuring chamber passages  50 ,  52 , respectively. 
     Referring now to  FIGS. 10 and 14 , the valve passage  54  and the delivery chamber inlet port  26  are each preferably provided by a generally cylindrical insert member  98  disposed within a through bore  99  of the body base section  90 . The insert  98  has a central bore  99  providing the valve passage  54 , a first radial passage  100  connected with the measuring chamber passage first section  53 A, and a second radial passage  101  providing the delivery chamber inlet port  26 . Further, the insert  98  also has a plurality of sealing members  102  disposed within annular grooves  103  in the insert outer surface  98   a  for sealing between the insert  98  and the body base section  90 . However, the valve passage  54  and/or the delivery chamber inlet port  26  may alternatively be provided by holes directly machined in the base section  90  (structure not shown). 
     By having such an insert  98 , the insert  98  and the valve member  60  may be formed of wear resistant materials, such as a tool steel, and the body base section  90  and main body section  92  may be formed of materials different than the materials of the insert  98  and the valve member  60 . For example, when used in a potentially corrosive environment, the body sections  90 ,  92  may be formed of stainless steel and when the weight of the injector  10  is an important consideration, the body sections  90 ,  92  may be formed of a lightweight material, such as aluminum. By providing the insert  98  as opposed to machining the passage  54  and the port  26  directly within the body sections  90 ,  92 , such a selection of different materials is made possible. 
     Referring to  FIGS. 2 and 5 , the injector  10  is typically used in a “bank”  11  of injectors  10  that includes a plurality of the injectors (e.g., four injectors  10 ) each coupled with a common manifold  106 . The manifold  106  includes a main lubricant passage  108  and a plurality of outlet bores  110  extending radially from the main passage  108  to an interface surface  107  of the manifold. Each injector  10  is disposable on the interface surface  107  such that the injector body inlet  14  is generally aligned with a separate one of the outlet bores  110 . 
     Referring to  FIGS. 1-5 , when the injectors  10  are used with a manifold  106 , the injector  10  preferably further comprises a connector  112  configured to couple the injector body  12  with the manifold  106 . The connector  112  has a central fluid passage  114 , a generally radial through passage  116  connected with central passage  14  and with the manifold passage  108 , and an outlet  118  disposed within the body inlet  14 . As such, lubricant within the manifold passage  108  flows into the radial passage  116 , a portion of which enters the connector central passage  114  and the remainder returns to the manifold passage to subsequently flow into the connectors  112  of adjacent injectors  10 . The portion of lubricant entering the connector central passage  114  then passes through the connector outlet  118  and into the injector inlet  14 , to flow therethrough as described in detail below. 
     Preferably, each connector  112  is formed generally as a threaded bolt  118  having an outer threaded section  118   a  engaged with an inner threaded section  56   a  of the injector body inlet chamber  56  and a head  120  disposed against a lower surface  109  of the manifold  110 , and extends through another radial passage (not shown) aligned with an associated radial passage  116 . However, the connector  112  may be formed so as to be disposed only in the outlet bore  110  and have any appropriate shape, or the body  12  may be formed to connect directly to the manifold  110  without a separate connector. Furthermore, the injectors  10  may also be alternatively formed to connect directly to a lubricant supply line  5  without any manifold. 
     Referring now to  FIGS. 18A-18D , in use, the injector  10  functions generally in the following manner. As lubricant pressure increases at the body inlet  14 , caused by operation of the pump  4 , the lubricant flows from the inlet chamber  56  (preferably from the associated manifold  100  and connector  112 ) and into the valve passage first end  54   a , while the valve member  60  is in the first position VP 1 , fluidly coupling the inlet  14  with the measuring chamber passage  52 , as depicted in  FIG. 18A . Lubricant does not enter the operating chamber passage  50  as the operating chamber  32  is filled with lubricant with the piston  30  at the piston initial position PP I , but rather flows through the measuring chamber passage  52  and into the measuring chamber  34 . Due to the relatively greater surface area of the piston first pressure surface  40  compared to the second pressure surface  42 , force on the piston first axial end  36   a  is greater than the force F 2  on the second axial end  30   b , causing the piston  30  to displace in the first direction D 1  while lubricant fills the measuring chamber  34  until the rod engagement surface  41  contacts the adjustment member stop surface  88 , as depicted in  FIG. 18B , such that the piston  30  is located at the piston maximum position PP M . As the measuring chamber volume increases, the corresponding decrease in volume of the operating chamber  32  forces lubricant from the chamber  32  and through the operating chamber passage  50  to the inlet chamber  56 . Due to the relative sizing of the pressure surfaces  40 ,  42 , the displacement of the piston  30  to the maximum position PP M , and thereby the filling of the measuring chamber  34  with the desired, predetermined quantity of lubricant, occurs more rapidly than with previously known injectors. At this point, no further lubricant is able to enter the measuring chamber  34 , which now contains the predetermined lubricant quantity, causing lubricant pressure to increase in the inlet chamber  56 . The pressure in the inlet chamber  56  is exerted on the valve member  60 , specifically the second plug section  66 B, and increases until sufficient to displace the valve member  60  from the first position VP 1  to the second position VP 2 , as depicted in  FIG. 18C . As such, the valve second plug section  66 B prevents flow through the valve passage first end  54   a  and the valve groove  64  fluidly connects the measuring chamber passage  52  with the delivery chamber inlet port  26 . Lubricant continues to flow into the operating chamber  32  until pressure in the chamber  32  is sufficiently high to overcome the surface area differential between the piston pressure surfaces  40 ,  42 . 
     Then, the piston  30  displaces in the second axial direction D 2  and causes lubricant in the measuring chamber  34  to flow out the bore second port  22 , through the measuring chamber passage  52  and the valve groove  64 , and into the delivery chamber  24 , as shown in  FIG. 18D . The displacement of lubricant from the measuring chamber  34  pushes an equal volume of lubricant out of the delivery chamber  24  through the body outlet(s)  16 , and ultimately to the delivery point DP. Once the lubricant is delivered, pressure within the injector  16  decreases, causing the springs  74 ,  75  to displace the valve member  60  to the valve first position VP 1  while the piston  30  is disposed at the piston initial position PP I , as depicted in  FIG. 18A , and therefore ready to repeat the injector cycle as described above. 
     It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as generally defined in the appended claims.