Technical Field

This invention relates to an improved pump and in particular to a pump for use in lubrication systems such as lubrication systems used in large size earthmoving equipment or other plant. Background Art

Lubrication systems are commonly used in large size earthmoving equipment such as drag lines, and excavators as used in mining to lubricate moving parts for example bearing or pins. The lubrication systems usually include more than one grease distribution system each of which includes a pump connected to a source of grease. Grease is supplied to a distribution block carrying a series of grease injectors. The grease injectors are connected to feeder lines for supplying grease to bearing, bushes, pins or other moving parts to be lubricated. The injectors may be operated at regular intervals to supply a charge or grease or other lubricant to the bearing, bushes or pins or other moving parts.

The pumps which are currently employed are, because of the harsh environment in which they are operating, often susceptible to damage from grit, lint or other contaminants in the grease supply. Generally the pumps includes a large number of independent parts which function independently of each other such that the pump fails when a single component fails or where the seals between parts weaken because of contaminants. For example, the current pumps which are used usually include ball valves and grit or other contaminant can prevent the balls of the ball valves seating correctly. As a result, and due to the lack of pressure in a grease line which can damage the bearings, bushes and/or pins or other moving parts, an alarm is triggered. In most cases, this involves the pump being replaced by a new pump which is obviously expensive. In addition, replacing of pumps means that it is necessary for the machine to stop operation resulting in machine down time and further costs. If the pumps are not replaced or repaired, damage to bearings, bushes, pins or other moving parts which are normally regularly lubricated can occur resulting in possible more expense and machine down time.

Summary of the Invention

The present invention aims to provide an improved pump which is particularly but not exclusively suited to use in lubrication systems which overcomes or alleviates one or more of the above disadvantages. Other objects and advantages of the invention

will become apparent from the following description.

The present invention provides in a preferred aspect a fluid pump having a main pumping chamber, a priming chamber for priming said main pumping chamber, an outlet from said main pumping chamber and a piston assembly associated with said chambers, said piston assembly being moveable sequentially to prime said pumping chamber with fluid from said priming chamber and to pump fluid from said pumping chamber through said outlet.

The fluid pump suitably includes a fluid passage or passages through which fluid is pumped from the pumping chamber, the fluid passage or passages being opened and closed with movement of the piston assembly. Suitably the fluid pump also includes a fluid passage or passages through which fluid is pumped from the priming chamber to the pumping chamber, the fluid passage or passages being opened and closed with movement of the piston assembly.

Preferably movement of the piston assembly in pumping fluid from the pumping chamber and priming of the pumping chamber from the priming chamber comprises a reciprocating longitudinal movement and a rotational movement.

The piston assembly may include an outlet port which during the pumping of fluid from the pumping chamber is aligned with an outlet flow passage through which liquid from the pumping chamber can flow. The outlet flow passage is suitably of a helical configuration such that during at least part of the longitudinal and rotational movement of the piston assembly during the pumping of fluid from the pumping chamber, said outlet port tracks or follows along and remains aligned with the flow passage to permit fluid to be pumped from the pumping chamber.

The pumping chamber suitably comprises a chamber of annular cross section and the piston assembly suitably includes a first piston of annular cross section and of complementary configuration to the pumping chamber for receipt within the pumping chamber. Preferably the annular chamber includes an outer wall in which the outlet flow passage is formed. The annular chamber is suitably defined by inner and outer sleeve- like members and the outer wall suitably comprises the wall of the outer sleeve-like member.

Preferably the piston assembly includes a second piston associated with the priming chamber. The priming chamber suitably includes or communicates with an inlet port through which fluid can flow into the priming chamber. Preferably the longitudinal

movement of the piston assembly causes the second piston to create a vacuum or partial vacuum in the priming chamber whereby fluid may be drawn in through the inlet port into the priming chamber.

Preferably a priming flow passage is adapted to connect the priming chamber with the pumping chamber to enable the pumping chamber to be primed with fluid from the priming chamber. Preferably a priming port adapted to communicate with said pumping chamber is provided, the priming port during at least part of the longitudinal and rotational movement of the piston assembly being aligned with the priming flow passage to permit liquid to flow from the priming chamber into the pumping chamber to prime the pumping chamber.

Preferably, the priming flow passage is of a helical configuration such that during longitudinal and rotational movement of the piston assembly during the priming of the pumping chamber, the priming port remains aligned with the priming flow passage to enable fluid to be pumped from the priming chamber into the pumping chamber. Preferably, the helical priming flow passage is on the opposite radial side to the helical outlet flow passage.

Preferably the priming port is blocked during pumping of fluid from the pumping chamber. Preferably also, the outlet port from the pumping chamber is blocked during priming of the pumping chamber. Preferably, the fluid pump includes an elongated outlet tube in which the piston assembly is supported for movement, the elongated outlet tube being adapted to extend into a source of fluid to be pumped. Preferably, a flow passage communicating with a fluid outlet is defined in the outlet tube, said flow passage communicating with said outlet flow passage. Preferably the fluid outlet is formed in a main body of the pump, the outlet tube extending from said the body.

Suitably, the priming chamber is formed within a lower end of the outlet tube.

Preferably the port comprises an inlet opening or openings in the lower end of the outlet tube. Means are suitably means movable with the second piston and are adapted to close the inlet opening or openings during pumping of fluid from the priming chamber to prevent fluid being pumped through the inlet opening or openings.

Preferably, the piston assembly includes a piston rod which extends longitudinally of the outlet tube.

Means are suitably provided for reciprocating and simultaneously rotating the

piston rod and piston assembly. The means for reciprocating and rotating the piston rod suitably comprises a reciprocating motor, a helical track, and means movable with the piston rod and co-operable with the helical track to cause rotation of the piston rod upon reciprocation thereof. Preferably the means movable with the piston rod comprise at least one roller or follower receivable within the helical track. The helical track suitably includes a pair of opposite helical track parts along which a roller or follower may move such that in reciprocating movement of the piston rod in opposite directions, the piston rod and thus piston assembly rotates in opposite directions.

Preferably, the helical outlet flow passage and helical priming passage follow similar paths to the helical track parts of the helical track respectively.

The motor suitably comprises a fluid motor, preferably a piston/cylinder motor and valve means are suitably provided for effecting reciprocating action of the motor and thus the pump. Preferably the valve means reverses the direction of fluid flow to the motor to reverse the direction of operation of the motor. Preferably, the valve means reverses the direction of fluid flow to the motor when the pump reaches or approaches the opposite ends of its reciprocating movement.

Suitably, the main body of the pump includes a chamber having an inlet port connectable to a source of pressurized fluid and an outlet port and the valve means controls the flow from the outlet port to opposite sides of the fluid motor. Preferably the chamber includes first and second pilot ports through which fluid from the chamber may flow to actuate the valve means, the first and second pilot ports being closed and opened in response to movement of the piston rod of the pump. Preferably the pilot ports are controlled by the rollers or followers.

The main body suitably includes means for mounting the pump to a fluid reservoir. The mounting means may comprise a mounting flange.

In a further aspect, the present invention provides a lubricant pump for pumping fluid from a lubricant container, said lubricant pump having a main body adapted to be mounted to said container, an elongated tubular member adapted to extend from said main body into said container, a pumping chamber and a priming chamber for priming said pumping chamber in a lower end of said tubular member, a piston assembly including first and second pistons associated with the respective said chamber, a piston rod coupled to said piston assembly and extending along said tubular member, and means for reciprocating and rotating said piston rod and piston assembly to sequentially prime

said pumping chamber with fluid from said priming chamber and to pump fluid from said pumping chamber.

Preferably the pump includes an outlet and wherein communication between the primary chamber and pumping chamber and pumping chamber and outlet is controlled by the reciprocating and rotating movement of the piston assembly.

Preferably a first helical passage is adapted to communicate with the outlet and said pumping chamber and a second helical passage is adapted to communicate the priming chamber with the pumping chamber, the first helical passage being of opposite hand to the second helical passage. Preferably a port communicating with the pumping chamber is adapted to track or follow, to be in communication with the first helical passage during part of the reciprocating and rotational movement of the piston assembly for pumping for fluid therethrough from said pumping chamber.

Preferably the pump includes a priming port adapted to communicate with the pumping chamber, and the second helical passage remains aligned with and communicates with the priming port during part of the reciprocating and rotational movement of the piston assembly for priming of the pumping chamber from the priming chamber.

The term "fluid" as referred to above and throughout the specification in reference to the material pumped by the pump may comprise any fluid including viscous fluids such as grease. Brief Description of the Drawings

In order that the invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate a preferred embodiment of the invention and wherein :-

Fig. 1 is a sectional view of the pump according to an embodiment of the invention mounted on a grease drum (shown in dotted outline);

Fig. 2 is a plan view of the main body of the pump;

Fig. 3 is sectional view of the main body of the pump along line A-A of Fig. 3; Figs. 4 and 5 are enlarged sectional views of the pump body and control valve at the bottom and top of the stroke of the pump;

Fig. 6 is a sectional isometric view of the lower end of the pump;

Fig. 7 illustrates in sectional view the low pressure and high pressure transfer

tubes within the main discharge tube of the pump;

Fig. 8 illustrates in sectional view the high pressure piston of the pump; and Figs. 9 to 11 are enlarged sectional views showing the lower end of the pump with the pumping pistons in different operational positions. Detailed Description of the Preferred Embodiment

Referring to the drawings and firstly to Figs. 1, there is illustrated a pump 10 according to an embodiment of the invention for supplying grease or other lubricant to a lubrication system typically a lubrication system which distributes grease or other lubricant to a plurality of injectors for lubricating parts of machinery. The pump 10 includes a main body 11 having a stepped bore 12 extending along a longitudinal axis of the body 11 and an outer high pressure lubricant discharge tube 13 which is secured to the main body 11 and extends axially therefrom. The upper end 14 of the discharge tube 13 is received and sealed within portion 15 of the bore 12 and is secured therein by means of a tube retaining nut 16 which is threadably engaged with the body 11 at 17 and cooperates with a collet 18 at the upper end of the tube 13 to secure the tube end 14 within the bore portion 15. The tube retaining nut 16 also includes a radially extending flange 19 which enables the pump 10 to be secured to a lubricant container such as a grease drum 20 (shown in dotted outline) by bolting through the flange 19 such that the tube 13 extends into the drum 20 and into the grease or other lubricant therein. The pump body 11 as shown in Figs. 2 and 3 includes a pair of grease outlet passages 21 and 22 which communicate with the interior of the tube 13. One passage 21 terminates in an enlarged threaded outlet 23 for threaded engagement by an outlet fitting 24. The outlet fitting 24 may be provided with a filter such as a screen to filter contaminants from the lubricant as it is pumped from the drum 20. The other passage 22 also terminates in an internally threaded outlet 25 for threaded engagement by an alternative outlet fitting.

The stepped bore 12 further includes an axial bore portion 26 for receipt of a piston rod 27 therethrough, the piston rod 27 being sealed to the bore portion 26 of the stepped bore 12 by means of an annular seal 28. The piston rod 27 extends into an upper chamber 29 in the main body 11 which comprises an extension of the bore 12. The piston rod 27 is connected at its upper end by means of a pinned connection 30 to an adaptor 31 (see also Figs. 4 and 5). The adapter 31 is connected to a reciprocating motor 32 in this embodiment a piston/cylinder pneumatic motor (shown schematically) having a

piston 33 arranged for reciprocation in a cylinder 33' and a piston rod 34 extending from the piston 33. The adaptor 31 includes a threaded shaft 34 which is longitudinally aligned with and connected to the piston rod 33. The adaptor 31 additionally includes a transversely extending bore 36 which receives opposite rollers or followers 37 which are biased apart by means of a biasing spring 38. The rollers or followers 37 are biased outwardly by the spring 38 to locate within and cooperate with a helically extending track or guide 39 (see Fig. 3 in dotted outline) formed in the inner wall of the upper chamber 29.

The track 39 comprise a pair of opposite track parts 39' and 39" of opposite hand which are joined at their upper and lower ends but which between the upper and lower ends extend helically in opposite directions firstly through ninety degrees from their upper ends to midway between the upper and lower ends and then back through ninety degrees to their lower ends. As the adapter 31 and connected piston rod 27 are reciprocated by the motor 32, the cooperation between the rollers or followers 37 and the track parts 39' and 39" causes rotational movement of the adaptor 31 and piston rod 27 about the longitudinal axis of the upper chamber 29. This rotational movement is a total of one hundred and eighty degrees as the rollers or followers 37 move from the upper ends of the tracks parts 39' and 39" to the lower ends thereof and back from the lower ends to the upper ends. The adaptor 31 and piston rod 27 as they are moved longitudinally initially rotate from the upper end of the track 39, ninety degrees in one direction in movement along one track part 39' (or 39") and back through ninety degrees along the one track part 39' (or 39") to the lower end of the track 39. In the opposite reciprocating movement, the adaptor 31 and piston rod 27 initially rotate ninety degrees in the opposite direction along the opposite track part 39" (or 39') and back through ninety degrees along that track part 39" (or 39') to the upper end of the track 39.

The helical track 39 also crosses upper and lower pilot ports 40 and 41 which are opened and closed by the rollers or followers 37 as described further below. An intermediate supply port 42 is also provided in the wall of the chamber 29 between the upper and lower ports 40 and 41. The body 11 further includes an inlet port 43 which is connected to a pressurised air supply line such that the chamber 29 is always pressurised when the port 43 is connected to the air supply.

Mounted to the main pump body 11 adjacent to the main chamber 29 is a valve body 44 having a valve chamber 45 in which a valve spool 46 is arranged for

reciprocation. The valve body 44 as more clearly shown in Figs. 4 and 5 includes upper and lower ports 47 and 48 which are aligned with and communicate with the upper and lower pilot ports 40 and 41 of the chamber 29. The ports 47 and 48 communicate through passages 49 and 50 respectively with the upper and lower ends 51 and 52 respectively of the valve chamber 45. It will be noted in Fig. 1 that the upper end 51 of the valve chamber 45 is closed by the cylinder 33' of the motor 32 but may be closed by any other end cap, plate or member. Further ports 53 and 54 in the valve body 44 are connected by connecting fluid lines 55 and 56 to the cylinder 35 on the lower and upper side respectively of the piston 33. The valve body 44 also includes vent ports 57 and 58. The outer tube 13 has a first upper part 59 and a separate lower part 60 (see Figs.

6 and 7) which is threadably connected at 61 to the upper part 59. The lower part 60 has a grease or lubricant inlet port or ports 62 at its lower end through which grease or lubricant enters the tube 13 to be pumped through the outlets 21 or 22. Inner portions of the upper tube part 59 and lower tube part 60 are internally rebated as at 63 adjacent the threaded connection 61. An outer high pressure sleeve 64 having an outer diameter slightly less than the inner diameter of the tube 13 is located coaxially within the tube 13 and has an enlarged annular end 65 located in the rebate 63. A low pressure transfer tube 66 having an outer diameter less than the inner diameter of the high pressure tube 64 has an annular projection 67 also located in the rebate 63. When the upper tube part 59 and lower tube part 60 are threadably engaged with each other and tightened, they cooperate to clamp the annular end 65 and projection 67 together in the rebate 63 to fix the sleeve 64 and tube 66 coaxially within the discharge tube 13. The annular space between the sleeves 64 and tube 66 defines a high-pressure piston chamber 68.

The lower end of the piston rod 27 terminates in an annular sleeve-like piston 69 (see Fig. 8) for receipt within the annular chamber 68, the sleeve-like piston 69 having a port 70 at its upper end. The outer sleeve 64 includes a helically extending flow passage 71 with which the port 70 is aligned and communicates during the supply stroke of the piston 69 as described further below. It will be noted that the annular projection 67 varies in thickness so that at the bottom of the stroke of the piston 69, the chamber 68 is not fully occupied by the piston 69.

A low-pressure transfer tube 72 coaxial with the piston rod 27 extends through the low pressure sleeve 66 and is secured to the piston rod 27 by means of a longitudinally extending bolt 73. A priming piston 74 which is movable within the lower

part 60 of the high pressure outlet tube 13 is secured between the head of the bolt 73 and transfer tube 72 and defines a low pressure priming chamber 75 above the piston 74. The transfer tube 72 includes a lower port 76 communicating through an annular groove 77 in the outer wall of the transfer tube 72 with the lower end of a helically extending transfer passage 78 which is on the opposite side to the helical passage 71. The helixes of the passages 71 and 78 however are same as that of the track 39. A port 79 is also provided in the low pressure sleeve 66 which is capable of communicating with the high pressure chamber 68 for charging the chamber 68 with grease as described below.

In use, the inlet port 43 is connected through a solenoid valve to a pressurised air supply (or alternatively to an pressurised fluid such as oil supply). To initiate operation of the pump 10, the solenoid valve is opened which causes the chamber 29 to be pressurised with air. With the pistons 69 and 74 retracted in the position of Fig. 11, the valve spool 46 is in the position of Fig. 4. Further as the adaptor 31, which in cooperation with the helical track 29 controls the turning angle of the piston rod 27 and thus pump pistons 69 and 74 and other pump elements movable therewith, approaches the bottom of its stroke, the rollers or followers 37 close off the pilot port 41 in the control valve chamber 29 as shown in Fig. 4 whilst the port 40 remains open to the pressure within the valve chamber 29.

Fluid pressure in the chamber 29 is then applied to the ports 40 and 47 and through the passage 49 to the upper part 51 of the valve chamber 45. At the same time the lower part 52 of the valve chamber 45 is vented through the passage 50 and valve spool 46 to the vent 48. The air pressure applied to the part 51 of the valve chamber 45 on the upper side of the valve spool 46 will move the spool 46 to the position of Fig. 5. This connects the port 54 to the port 42 and thus connects fluid pressure in the chamber 29 to the upper side of the piston 34 through the fluid line 56 to force the piston 33' and attached piston rod 27 downwards.

As the pump piston rod 27 undergoes its downward stroke, it will because of the movement of the rollers or followers 37 along the helical path defined by the helical track 39' (or 39"), rotate firstly through 90 degrees in one direction and then back through 90 degrees in the opposite direction. During the downward and rotational movement of the piston rod 27, the high pressure piston 69 is advanced into the chamber 68 between the high pressure sleeve 64 and the transfer tube 66. Any grease or lubricant in the chamber 68, because of the advancing piston 63, will be forced from the chamber 68 between the

inner wall of the piston 69 and outer wall of the transfer tube 66 and out through the port

70. The port 70 is aligned with the helical flow passage 71 and will track along and remain in communication with the passage 71 as the piston rod 27 moves downwardly and rotates so that the grease or lubricant will flow into the passage 71 and then into the space 80 between the piston rod 27 and lubricant discharge tube 13. The grease or lubricant will then flow up into the body 11 and through one or both of the outlet passages 21 and 22 to enter the lubrication system. The lubrication system typically comprises a system of grease hoses and valves and/or injectors such that moving part of a machine system to be lubricated are supplied with a charge of grease or other lubricant. During the downward movement of the piston rod 27, and because of the direction of rotation of the piston rod 27, the port 79 is blocked from communication with the helical passage 78.

At the same time that the above is occurring, the priming piston 74 moves downwardly in the tube 13 as in the position of Fig. 10 to create a vacuum or partial vacuum in the low pressure transfer chamber 75. As the piston 74 passes the input ports 62 in the lower outer tube part 59, the vacuum in the chamber 75 causes grease to be drawn into the chamber 75. The outlet ports 62 are preferably formed such that as the piston 74 passes the ports 62 during the discharge stroke, the ports 62 close. The ports 62 for this purpose may be formed by spaced longitudinally extending slots and a valve member movable with the piston 74 and containing a corresponding set of slots may rotate with rotation of the piston rod 27 to close the ports 62 so that when the priming stroke begins, grease is not forced out of the ports 62.

With the pistons 69 and 74 at the bottom of their stroke, the high pressure outlet port 70 is closed off being no longer aligned with the passage 71. Further in this position, the annular high pressure chamber 68 is connected through the helical passage 78 (and annular groove 77 and port 76) to the priming chamber 75.

As the adaptor 31 approaches either end of its stroke, the rollers or followers 37 close of the pilot ports 40 and 41 in the chamber 29. This has the effect of unbalancing the pressure operating on the ends of the valve spool 46 to force it to move to the opposite end of its chamber 45. This changes the porting in the valve chamber 45 to change the direction of flow to the cylinder 33 to cause a reversing action of the piston 34 to effect an opposite reciprocating movement of the pumping element comprising the piston rod 27 and attached pistons 71 and 74.

As the pump pistons 69 and 74 commence their upward stroke, grease is forced from the priming chamber 75 by the piston 74 through the helical passage 78 in the low pressure transfer tube 72 into the port 79 which is aligned with the passage 78 and thus into the high pressure chamber 68 to prime the chamber 68. The passage 78 because of its helical configuration remains aligned with the port 79 as the pistons 69 and 74 (and low pressure transfer tube 72) rotate and move upwardly. Priming of the chamber 68 continues as the pump pistons 69 and 74 move upwardly with grease also being forced through the port 76 and groove 77 into the helical passage 78 until the port 76 is covered by the low pressure tube 66 as shown in Fig.11 at the top of the stroke of the pump 10. The high pressure chamber 68 is thus charged with grease ready for the next downward stroke of the pump 10 which will commence automatically due to the reversing of the valve spool 46 as described above. During the upward stroke, the piston rod 27 will rotate in the opposite direction to the direction of its rotation in the downward stroke due to the rollers or followers 37 of the adaptor 31 moving along the other arcuate track part 39' (or 39") of the helical track 39 initially through ninety degrees in one direction and then ninety degrees in the opposite direction. Further the port 70 during this movement will remain blocked as, due to the reverse rotation of the piston rod 27 and thus piston 69, it does not align with the helical flow passage 71. It will however again become aligned with the flow passage 71 in the next downward stroke of the piston as the piston rod 27 rotates in the opposite direction.

The pump 10 will continue to undergo an automatic reciprocating pumping action as described above provided air pressure is continued to be supplied to the port 43 through the solenoid valve.

Whilst the pump 10 is preferably driven by pneumatic pressure, it may also be driven by hydraulic pressure depending on the system application and requirement.

The embodiment described above may of course be considerably varied in design.

For example the rollers or followers 37 may be in the form of fingers or other projecting members which locate within or cooperate with the helical track 39. The driving motor

32 may be in configurations other than that described and further the valve for controlling the operation of the motor 32 whilst described as a spool valve may be any other form of valve. Some of the separate components of the pump may also be formed integrally.

The pump whilst particularly suited to use in lubrication systems may also be

used in any other pumping application.

The terms "comprising" or "comprises" as used throughout the specification and claims are taken to specify the presence of the stated features, integers and components referred to but not preclude the presence or addition of one or more other feature/s, integer/s, component/s or group thereof.

Whilst the above has been given by way of illustrative embodiment of the invention, all such variations and modifications thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of the invention as herein defined in the appended claims.