AIR-OPERATED PUMP

BACKGROUND OF THE INVENTION

[0001 ] This invention relates generally to lubrication equipment, and more particularly to pumps operated by air motors for pumping lubricant such as oil or grease.

[0002 ] Fig. 1 shows a conventional pump 1 operated by an air motor. The pump includes a head 3 comprising a cylinder 5, a piston 7 reciprocal up and down in the cylinder, and a plunger 9 connected at its upper end to the piston and extending down from the piston generally co-axially with respect to the cylinder. A pump tube 11 is connected to the head and surrounds the plunger. An air motor 13 supplies air under pressure to the head for reciprocating the piston in the cylinder to move the pump plunger up and down in the pump tube through pumping strokes, as will be understood by those skilled in this field. In general, the air motor includes an air valve system comprising a pair of air signal valves 15, a relay valve or amplifier 17 and a power valve 21, all of which are enclosed in respective housings 23, 25, 27 separately attached to the top and one side of the pump head 3. This arrangement has certain drawbacks. For example, if a problem develops with the air valve system, the specific valve component causing the problem must be identified and the appropriate housing or housings must be removed for repair and/or replacement. Isolation of the problem component may not be possible or practical in the field (i.e., the site where the pump is in operation). If not, either the entire pump must be shipped off for service or all valve components and all housings must be removed from the pump and shipped off for service. These options are inconvenient.

[ 0003 ] Accordingly, there is a need for an improved pump design which facilitates servicing of an air valve system of a pump of the type described above.

SUMMARY OF THE INVENTION

[0004 ] In one embodiment, this invention is directed to an air-operated pump for pumping material, particularly a lubricant such as oil or grease. The pump comprises a head defining a cylinder, a piston reciprocal up and down in the cylinder, and a pump plunger having an upper end connected to the piston and a lower end. An air motor module supplies air under pressure to the head for reciprocating the piston in the cylinder to move the pump plunger up and down in the pump tube through pumping strokes. The air motor module comprises a housing at one side of the head and an air valve system in the housing

for supplying air under pressure to the head for reciprocating the piston in the cylinder. The air valve system comprises air signal valves, a relay valve and a power valve. A fastening system is provided for securing the housing to the head such that the housing may be removed as a unit from the head (e.g., to facilitate servicing of the air valve system). [ 0005 ] Other objects and features will be in part apparent and in part pointed out hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Fig. 1 is a cross sectional elevation of portions of a prior air-operated pump;

[ 0007 ] Fig. 2 is a perspective of one embodiment of a pump with an air motor module of this invention;

[0008 ] Fig. 3 is a front elevation of the pump of Fig. 2;

[0009 ] Fig. 4 is a side elevation of the pump;

[0010 ] Fig. 5 is a vertical section taken in the plane 5—5 of Fig. 3, showing a piston at the bottom of its stroke;

[0011 ] Fig. 6 is a view similar to Fig. 5 but showing the a piston at the top of its stroke;

[ 0012 ] Fig. 7 is a vertical section taken in the plane 7-7 of Fig. 4, showing the piston at the bottom of its stroke;

[0013 ] Fig. 8 is a side elevation of the air motor module of Fig. 1;

[0014 ] Fig. 9 is an exemplary pneumatic circuit of an air valve system of the air motor module;

[0015 ] Fig. 10 is an enlarged view showing an upper signal valve of the air valve system;

[0016] Fig. 11 is a vertical section taken in the plane 11 — 11 of Fig. 8 showing details of the air valve system during an upstroke of the piston;

[ 0017 ] Fig. 12 is a view similar to Fig. 12 but showing the air valve system during a down stroke of the piston;

[0018 ] Fig. 13 is a vertical section taken in the plane 13—13 of Fig. 15 showing details of a power valve of the air valve system;

[0019 ] Fig. 14 is an exploded view of components of the power valve;

[0020 ] Fig. 15 is an elevation showing the back face of the air motor module; and

[0021 ] Figs. 16—18 are views showing a second embodiment of a pump of this invention Corresponding reference numbers indicated corresponding parts throughout the drawings.

DETAILED DESCRIPTION

[0022 ] Figs. 2-15 illustrate one embodiment of an air-operated pump of this invention, designated in its entirety by the reference number 101. The pump is operable for pumping material, particularly a lubricant such as oil or grease, from a source of such material such as a container (not shown). The pump 101 of this particular embodiment is particularly adapted for pumping oil.

[ 0023 ] In general, and referring to Figs. 1-7 the pump comprises a pump head 105 defining a cylinder 107 and a piston 111 reciprocal up and down in the cylinder. The cylinder 107 is divided into a first expansible chamber 115 at one side of the piston (the upper side as shown in Fig. 5) and a second expansible chamber 117 at the opposite side of the piston (the lower side as shown in Fig. 6). A pump plunger 121 extends down from the piston 111 generally co-axial with the cylinder 107. The plunger 121 has an upper end connected to the piston 111 and a lower end. An elongate pump tube 125 is connected to the head 105 and surrounds the plunger 121. The pump tube extends down below the lower end of the plunger. An air motor module 131 supplies air under pressure to the pump head 105 for reciprocating the piston in the cylinder to move the pump plunger up and down in the pump tube through pumping strokes. The air motor module 131 comprises a housing, generally designated 141, at one side of the pump head 105 and an air valve system, generally designated 145 (Fig. 5), in the housing for supplying air under pressure to the head for reciprocating the piston in the cylinder. The air valve system 145 includes a number of valves which will be described in more detail later. A fastening system, generally designated 151, is provided for securing the air motor module 131 to the head 105 such that the module may be removed as a unit from the head for repair or replacement of one or more components of the air valve system 145. The ability to remove the entire module 131 as a single unit facilitates servicing of the pump, as will become apparent. Each of the above components is described in more detail below.

[0024 ] In the embodiment shown in Figs. 2-7 the pump head 105 comprises an inner cylinder wall 155 (Fig. 5) defining, in part, the first and second expansible chambers 115, 117 of the cylinder 107 and an outer cylinder wall 159 co-axial with and spaced from the inner wall 155 to define an annular air space 161 between the walls communicating with an exhaust outlet 165. The inner cylinder wall 155 is generally cylindrical in shape. The outer cylinder wall 159 has cylindrical portion 159A and a non-cylindrical (e.g., channel-shaped) portion 159B with a flat planar face 165 which mates with the air motor module 131, as will be described. The pump head 105 also includes upper and lower end caps designated 171 and 173, respectively, for closing the upper and lower ends of the pump head and respective chambers 115, 117 of the cylinder.

[0025 ] Referring to Figs. 5-7, the plunger 121 is connected at its upper end to the piston 111 by a fastener 177. Other means may be used for connecting the plunger to the piston. The lower end of the plunger is recessed to form a check-valve chamber 181. Flow into and out of this chamber is controlled by a first check valve 183 comprising a valve body 185 in the lower end of the plunger 121, an axial flow passage 187 through the valve body, a valve seat 189 at the upper end of the flow passage, and a valve member comprising a ball 193 movable between a closed position in which it is seated to block flow through the flow passage 187 and an open position spaced from the seat 189 to allow flow. A seal 195 around the valve body seals against the inside wall of the pump tube.

[0026] In the illustrated embodiment, the pump tube 125 comprises an upper tubular part 201 attached to the lower end cap 173 of the pump head 105 and a cylindrical bearing 205 fitted in the upper tubular part 201 for supporting the plunger as it reciprocates. The bearing 205 extends up from the pump tube into an opening in the lower end cap 173. The pump tube 125 also has a lower part comprising a sleeve 211 having a threaded sealing fit at its upper end with the upper tubular part 201 of the pump tube. The upper and lower parts of the pump tube 201, 211 are co-axial with the plunger 121 and spaced from the outer surface of the plunger to define upper and lower pumping chambers 215, 217 above and below the location 195 where the first check valve 183 seals against the inside surface of the pump tube sleeve 211. The upper pumping chamber 215 communicates with the check valve chamber 181 via one or more holes 221 in the plunger 121 for flow of lubricant from the check valve chamber into the upper pumping chamber. Lubricant is expelled from the upper pumping chamber 215 via an outlet 225 (Fig. 7) in the upper part of the pump tube.

[0027 ] A second check valve 231 is provided at the lower end of the pump tube 125 at a location spaced below the lower end of the plunger 121 for controlling flow into a lower pumping chamber 217. The second (lower) check valve 231 comprises a valve body 235 having a sealing fit in the lower end of the pump tube sleeve 211, an axial flow passage 239 through the valve body, a valve seat 241 at the upper end of the flow passage, and a ball valve 243 movable between a closed position in which it is seated to block flow through the flow passage 239 to an open position spaced from the seat to allow flow into the lower pumping chamber 217. A seal 245 around the valve body seals against the inside wall of the sleeve 211 of the pump tube.

[0028 ] As illustrated in Fig. 8, the housing 141 of the air motor module 131 comprises a solid generally rectangular monolithic block 251 of suitable material (e.g., metal) having a front face 255, a back generally planar face 257 which mates with the flat generally planar face 165 of the outer cylinder wall 159 of the pump head 105, opposite side faces 261, a top face 265 and a bottom face 267. The housing 141 also includes an upper cover 271 which is secured to the top face of the block by suitable fasteners 275 (Fig. 2), and a lower cover 279 similarly secured by suitable fasteners (not shown) to the bottom face of the block 251. The housing 141 can have other configurations without departing from the scope of this invention. For example, while the housing block 251 described above and shown in the drawings is a one-piece monolithic block, it can be fabricated as multiple pieces secured together to form a single unitary structure. The block 251 could also have a shape other than rectangular. Desirably, the housing 141 and its contents are removable from the pump head 105 as a unit. There is no need to remove multiple components separately in order to remove and replace components of the air valve system 145.

[0029 ] The fastening system 151 for securing the air motor module 131 to the pump head 105 comprises, in one embodiment, one or more fasteners 285 (e.g., four threaded fasteners are shown in Fig. 2) extending through one or more fastener holes 289 (Fig. 15) in the block 251 and into tapped holes (not shown) in the pump head 105. The housing 141 can be quickly and easily removed from the pump head simply by removing these fasteners. Other fastening systems can be used to secure the module to the pump head in a releasable manner.

[0030 ] The housing 141 has an air inlet 301 (Fig. 11) for receiving air under pressure from the aforementioned source to operate the air valve system 145 of the air

motor. The housing also has a pair of exhaust outlets 305 (Fig. 11) for exhausting air from the upper and lower cylinder chambers 115, 117 during operation of the air motor.

[0031 ] Fig. 9 illustrates an exemplary pneumatic circuit of the valve system 145 in the housing 141. As shown, the system 145 comprises two air signal valves 315, 317, a relay valve 321 and a power valve 325, all of which are received in respective recesses in the housing. By way of example, these recesses may be formed by machining parallel vertical bores in the block 251 of the housing, as will be described. This arrangement provides easy access to the valves simply by removing the covers 271, 279. The air signal valves 315, 317, relay valve 321 and power valve 325 are operated by pressurized air supplied from a suitable source (e.g., a compressor), and they operate in synchronization to reciprocate the piston in the cylinder through successive strokes to effect the pumping action of the pump.

[0032 ] The air signal valves 315, 317 are pressure-differential valves and function to signal or detect the position of the piston 111 as it reciprocates in the cylinder 107. The first (upper) signal valve 315 is adapted to detect the position of the piston as it approaches the upper end of the cylinder, and the second (lower) signal valve 317 is adapted to detect the position of the piston as it approaches the lower end of the cylinder. An exemplary first (upper) signal valve 315 is shown in Fig. 10 as being positioned in a vertical bore 331 in the housing block 251. The valve 315 comprises a valve body 335 having a sealing fit in the bore 331, and a flow passage 336 through the valve body. A valve member 337 is movable in the passage 336. The valve member 337 has a diaphragm seal 341 at one end and a ball seal 345 at its opposite end. The diaphragm and ball seals 341, 345 are in communication with the upper chamber 115 of the cylinder via respective passages 351, 353 communicating with two small upper cylinder ports 357, 359 in the inner wall 157 of the cylinder 107. The diaphragm seal 341 has an exposed area substantially greater than (e.g., six times greater than) the exposed area of the ball seal 345 to provide the pressure differential necessary to move the valve member 337 between positions controlling the flow of air through passages 351 and 353 from the upper cylinder chamber 115, an exhaust port 365 in the valve member 337 communicating with atmosphere via a passage 371, and a relay valve port 373 communicating with one (upper) end of the relay valve 321 via a passage 373. The second (lower) signal valve 317 may be of identical construction and have diaphragm and ball seals in communication with the lower chamber 117 of the cylinder 107 via respective passages 381, 383 communicating

with two small lower cylinder ports 385, 387 in the inner wall 157 of the cylinder. The lower signal valve 317 controls the flow of air through an exhaust port 391 in the valve member and related exhaust passage 393, and also through a relay port 397 communicating with an opposite (lower) end of the relay valve via a passage 399. Other types of differential valves may be used.

[0033 ] Referring to Figs. 9 and 11, the relay or amplifier valve 321 is positioned in a bore 401 (e.g., a vertical bore in Fig. 11) in the housing block 251 and controls the flow of air through five ports, namely, an air inlet port 405 communicating with the main air inlet 301 via a passage 407, two exhaust ports 411, 413 communicating with atmosphere via passages 415, 417, and two power valve ports 421, 425 communicating with ports 427, 429 at opposite ends of the power valve 325 via passages 431, 433 for shifting the power valve in opposite directions. The relay valve 321 comprises a valve member, e.g., a spool 441 (Fig. 11) having seals which seal against the cylindrical wall of the bore 401. The bore 401 is connected at opposite ends to respective relay ports 373, 397 (via passages 377, 399) such that the spool 441 is shifted in one direction or another depending on which of the two relay ports is open (as controlled by the signal valves). The upper and lower ends of the bore 401 containing the spool 441 are closed by plugs 451, 453 having sealing fits in the bore and stems 457 which project into openings in the upper and lower covers 271, 279, respectively. The stems 457 may be pushed to move the plugs 451, 453 to manually shift the relay valve 321 during servicing, if necessary or desired.

[0034 ] Referring to Figs. 11, 13 and 14, the power valve 325 is positioned in a bore (e.g., a vertical bore 471) in the housing block 251 alongside the bore 401 for the relay valve 321. The power valve 325 comprises a perforated sleeve 475 held in a fixed location in the power valve bore. The sleeve 475 is cylindrical and is formed with a plurality of circumferential rows of openings 481 spaced at intervals along the sleeve and separated by seals 485 which seal against the wall defining the power valve bore 471. In this particular embodiment, there are five such rows. Each of the five rows of openings constitutes a port P1-P5 for the flow of air. Two sets of one or more openings corresponding to ports 427 and 429 are provided adjacent opposite ends of the sleeve (Fig. 14). The power valve 325 also includes a valve member comprising a spool 501 inside the sleeve 475 movable along the axis of the sleeve to control the flow of air through the ports P1-P5. As shown in Fig. 14, the spool 501 has a series of larger-diameter sections or lands 505 that are spaced apart

and carry seals 507 for sealing against the inside cylindrical surface of the sleeve. The upper and lower ends of the power valve bore 471 are connected to respective power valve ports 421, 425 of the relay valve 321 by respective passages 431, 433 such that the power valve spool is shifted in one direction or the other depending on which power valve port is open (as controlled by the relay valve). As described below, the power valve functions to deliver air under pressure from the main air inlet 301 to the lower and upper chambers 115, 117 of the cylinder 107 (via passages 521 and 523 connected to respective large cylinder ports 531, 533 adjacent the upper and lower ends of the cylinder 107) to reciprocate the piston in the cylinder. The use of the perforated sleeve 475 reduces the travel distance of the spool 501, since the diameter of the openings 481 is relatively small (e.g., 0.125 in.).

[ 0035 ] The various exhaust ports of the air valve system 145 communicate with the annular space 161 and exhaust outlet 165 (Fig. 5) in the pump head 131.

[0036] In use, the pump 101 is mounted in an operating position, e.g., on a container containing a supply of lubricant such as oil. A cycle of operation of the pump is described below.

[0037 ] At the start of an upstroke of the piston 111 in the cylinder 107, the air valves of the air module are positioned as shown in Fig. 11. In this state, the spool 501 of the power valve 325 is positioned for the delivery of air under pressure from the main air inlet 301 to the lower chamber 117 of the cylinder via ports P3 and P4 in the power valve sleeve 475 and passage 523 to the large cylinder port 533 in the lower chamber of the cylinder, and for the exhaust of air from the upper chamber 115 of the cylinder via the large cylinder port 531 in the upper chamber of the cylinder, passage 521, ports Pl and P2 in the power valve sleeve 475, and exhaust passage 305. As a result, the piston is driven up in the cylinder. The two small cylinder ports 385, 387 toward the lower end of the cylinder 107 are pressurized, in response to which the pressure differential across the lower signal valve 317 causes the lower signal valve member to move up to a position in which the diaphragm and ball seals 341, 345 are seated to close the passages 381, 383 and to open the relay valve port 397 and exhaust port 391. At the same time, the upper chamber 115 of the cylinder above the piston is open to atmosphere via the upper large cylinder port 531. The upper and lower ends of the upper signal valve 315 are in communication with the upper chamber 115 of the cylinder 107 via the upper small cylinder ports 357, 359 and passages 351, 353. Because the air in the upper chamber 115 is exhausted to atmosphere, no significant positive pressure is applied to the upper signal valve 315.

[ 0038 ] As the piston 111 moves up in the cylinder 107 (Fig. 6), it pulls the plunger 121 up in the pump tube 125. This movement causes the upper check valve 183 to close and the size or volume of the upper pumping chamber 215 to decrease, which results in the discharge of lubricant from the chamber through the outlet 225 in the pump tube. Simultaneously, the size or volume of the lower pumping chamber 217 increases, which results in a pressure reduction sufficient to open the lower check valve 231 and draw additional lubricant from the lubricant supply into the lower pumping chamber 217.

[0039 ] As the piston 111 moves toward the top of its upstroke, it moves past the small upper cylinder port 359 in the upper chamber 115 of the cylinder. When this happens, air pressure in the lower (pressurized) chamber 117 moves the ball seal 345 of the upper air signal valve 315 away from its seat to open the relay port 373 and close the exhaust port 365. In response, the spool 441 of the relay valve 321 moves to open the air inlet port 405 and the power valve port 421 to pressurize passage 431 to the upper end of the power valve 325. The resulting increase in pressure causes the spool 501 of the power valve 325 to shift to the position shown in Fig. 12 in which air under pressure is delivered to the upper chamber 115 in the cylinder 107 via the air inlet 301, ports P2 and P3 in the power valve sleeve 475, and passage 521 to the large upper cylinder port 531, and air is exhausted from the lower chamber 117 in the cylinder via the lower large cylinder port 533, passage 523, ports P4 and P5 of the power valve sleeve, and the lower exhaust outlet 305. As a result, the piston 111 reverses direction to move through a down stroke.

[0040 ] As the piston is driven down, the two small upper cylinder ports 357, 359 are pressurized, in response to which the pressure differential across the upper signal valve 315 causes the valve member 337 to move down to a position in which the diaphragm and ball seals 341, 345 are seated to close the passages 351 and 353 and to open the relay valve port 373 and exhaust port 365. At the same time, the lower chamber 117 of the cylinder below the piston is open to atmosphere via the lower large cylinder port 533. The lower signal valve 317 is in communication with the lower chamber 117 of the cylinder via the lower small cylinder ports 385, 387. Because the pressure in the lower chamber is open to atmosphere no significant positive pressure is applied to the lower signal valve.

[0041 ] As the piston 111 moves down (Fig. 7), the plunger 121 is pushed down in the pump tube 125, which causes the upper pumping chamber 215 to increase in size and the lower pumping chamber 217 to decrease in size. As a result, the lower check valve 231

closes and the upper check valve 183 opens to allow lubricant to flow from the lower pumping chamber 217 into the upper pumping chamber 215.

[ 0042 ] As the piston moves toward the bottom of its downstroke, it moves past the lower small cylinder port 385 in the cylinder. When this happens, air pressure in the upper (pressurized) chamber 115 moves the ball seal 345 of the lower air signal valve 317 away from its seat to open the relay port 397 and close the exhaust port 391. In response to the pressure in the upper cylinder chamber 115, the spool 441 of the relay valve 321 moves to open the port 405 admitting main air line pressure to the power valve port 425 to pressurize passage 433 to the lower end of the power valve 325. The resulting increase in pressure causes the power valve 325 to shift up to the position shown in Fig. 11 in which air under pressure is delivered to the lower chamber 117 in the cylinder and air is exhausted from the upper chamber 115 in the cylinder, as described previously. As a result, the piston reverses direction to move through another upstroke, and the sequence repeats.

[0043 ] Figs. 16-18 show a second embodiment of an air-operated pump of this invention, generally designated 701. The pump is essentially identical to the pump 101 of the first embodiment, except that is modified to pump a more viscous lubricant such as grease. The plunger 705 and pump tube 709 are substantially longer and a device sometimes referred to as a shovel 715 is attached to the lower end of the plunger for pulling a more viscous material such as grease up into the pumping chamber of pump tube. As this construction is not part of this invention, further detail is not provided. However, it will be noted that an air motor module 721 identical to the module 131 described in the previous embodiment is attached to the pump head at one side of the head to reciprocate the piston and plunger to effect the necessary pumping operation.

[0044 ] It will be apparent from the above description that an air-operated pump of this invention is an improvement over prior systems of the type shown in Fig. 1. In the event the air valve system 145 needs to be serviced, the entire air motor module 131 may easily and quickly be removed as a unit and replaced with another unit to minimize down time of the pump. Further, in the event the pump is not operating properly, the modular nature of the air motor eliminates the need to determine in the field which if any of the air valve components may be in need of service. The entire module 131 is simply removed and sent to the appropriate location for analysis and servicing. Still further, the air motor module is relatively small and compact to facilitate handling and storage.

[ 0045 ] When introducing elements of the present invention or the preferred embodiment(s) thereof, the articles "a", "an", "the" and "said" are intended to mean that there are one or more of the elements. The terms "comprising", "including" and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements. Further, the terms "upper", "lower", "down" and "up" are used for convenience only, and it will be understood that other orientations (e.g., non-vertical or reverse) are possible.

[0046] In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

[0047 ] As various changes could be made in the above constructions, products and methods without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.