US2997961A - Pneumatic pumping apparatus - Google Patents

Description

Aug- 29, 1961 A. D. MGDUFFIE 2,997,961

PNEUMATIC PUMPING APPARATUS Filed Aug. 17. 1959 2 Sheets-Sheet l www ATTORA/Y Allg 29, 1951 A. D. MCDUFFIE 2,997,961

PNEUMATIC PUMPING APPARATUS Filed Aug. l?, 1959 2 Sheets-Sheet 2 if Z/ ,a Y ff f B f//f #1% W f W ff Zi @j ATTORNEY Unite Patented Aug. 29, 1961 2,997,961 PNEUMATIC PUMPING APPARATUS rchie D. McDuflie, Waterford, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Aug. 17, 1959, Ser. No. 834,319 6 Claims. (Cl. 103-152) This invention relates to pumping apparatus and more particularly to pneumatically operated apparatus for pressurizing iiuids such as liquid fuel in supplying the latter continuously under controlled conditions for use as in operating an internal combustion engine.

An object of the present invention is to provide improved apparatus for pumping liquid fluid, the apparatus being capable of placing the uid under preselected pressure thereby inherently providing a positive and reliable feed. Another object is to provide a pumbing apparatus involving a minimum number of moving parts and in which many of the actuating parts remain at rest during much of the period of use thereby contributing to reliability and low maintenance costs as well as quietness in operation.

A feature of the invention is an apparatus comprising a low pressure pump arranged to supply liquid to a pneumatically operated pump of low capacity and high operational cyclic frequency, the latter pump being connected to supply an accumulator of high capacity and low operational cyclic frequency. Another feature is a combination of a diaphragm pump of high cyclic frequency f operation connected to supply an accumulator of low cyclic frequency of operation, both the pump and the accumulator being operable by fluid such as air under pressure to supply liquid such as liquid fuel under elevated pressure from a low pressure source of supply.

These and other important features of the invention Will now be described in detail in the specification and then pointed out more particularly in the appended claims.

In the drawings:

FIGURE 1 is a somewhat diagrammatic representation of apparatus constituting an embodiment of the present invention, an accumulator and a pump of that apparatus being shown in section and other elements of an engine fuel system being shown with suitable connecting uid lines;

FIGURE 2 is an enlarged sectional view of portions at one side of the pump shown in FIGURE l, and as seen looking in the direction of the arrows 2 2 in that figure;

FIGURE 3 is a sectional View of the other side of the pump looking in the direction of the arrows 3-3 in FIGURE l;

FIGURE 4 is a sectional View of details of the structure in the accumulator of FIGURE l as seen looking in the direction of the arrows 4-4 of FIGURE l;

FIGURE 5 is a sectional view looking in the direction of the arrows 5 5 in FIGURE 4; and

FIGURE 6 is a fragmentary View of elements of an over-centering device, certain parts being omitted to clarify the showing.

In FIGURE l a tank 10 is shown to represent a vessel for holding a supply of liquid fuel such as gasoline. The apparatus of the present invention is devised to convey this liquid under pressure to a point of use such as an injection nozzle of an engine. A second tank 12 is shown for retaining a pressurized supply of uid such as air for actuating the pumping apparatus. This tank may be taken as part of an air suspension system of a vehicle served by the engine.

A power driven pump 14 is closely associated with the fuel supply tank 10 for urging gasoline through a line 16 under low pressure. A relief valve 18 is provided to enable the pump 14 to operate continuously despite momentary iioW stoppages in the line 16. Various types of low pressure pumps could be used in place of the gear pump 14 illustrated and such pumps may be located within the tank 10. The close association of the pump 14 with the tank i0 is desirable to place the fuel under positive pressure in as much o-f the system as possible to avoid Vapor-lock which could otherwise Occur because of elevated temperature and/ or high fuel volatility.

Air under relatively high pressure is handled by a line 20 leading from the pressurized tank 12, to a tapped inlet 22 (see FIGURE 4) of a block member 24 of an accumulator indicated generally at A. The inlet 22 communicates -with two diverging passages 26 and 28. Passage 28 is connected with a recess 30 in the underside of the block member 24 and the passage 26 is connected with a port member 32 leading to an air chamber 34 within the accumulator A. Flow through the member 32 is controlled by a valve 36. A diaphragm 38 is interposed between the block member 24 and the accumulator A is pierced not to block the passage 26. This diaphragm traverses the recess 30.

A port member 40 is arranged :to control air flow from the recess 30 by -way of a vertical passage 42 and a line 44 to a bore 46 in the pump P as seen in FIGURES l and 2. Flow of air from this bore to an air chamber 48 of the pump P is by way of a conventionally constructed plunger valve assembly 50 as seen in FIGURE 2. Details of this valve form no part of the present invention but a spring and pressure actuated plunger 49 is provided to control ports 51 of the valve assembly. These ports are for the admission of air under pressure to the chamber 48 for actuating the pump P as will further appear.

The pump P is such as to operate at a relatively high cyclic frequency with a low liquid capacity per cycle periodically to fill the accumulator A which operates at a relatively low cyclic frequency and with a relatively high liquid capacity-ie. the accumulator A iills periodically with fuel and each fill is accompanied lby multiple cycles of operation of the pump P. A more elaborate description of the operation is given hereinafter.

The pump P comprises a cover 52 and main casing parts 54 and 56. The casing part 54 defines the bo-re 46 and the part 56 encloses the valve .assembly 50. Interposed between the main casing parts is a diaphragm 58 reinforced on its dry or air side by a plate 60. An upstanding annular flange 62 of the diaphragm is rmly held or locked in position between coaxial shoulder surfaces 64 and 66 formed on the casing parts 54 and 56 respectively. The diaphragm 58 separates the air chamber 48 from a liquid or pumping chamber 68, the latter being defined by the cover 52, the casing part 54 and the diaphragm. An O-ring 70 is arranged in a channel 72 formed in the part 54 to form a seal with the cover 52. Another O-ring 74 (FIGURE 2) is employed to seal the bore 46 at the interface between the pump parts 54 and 56.

One end of a shaft 76 is xed to the center of the pump diaphragm stiifening plate `60 and bears two spaced shoulder portions 78 and 80. A valve operating arm 82 is slotted as at 84 for the reception of the shaft 7.6. The arm bears an integral depending leg 86 having shoulder 88 arranged adjacent to but out of contact with the smooth side of a bolt 90 fixed to the casing part 56. The arm extends to the left as viewed in FIGURE 2 and terminates in a bifurcated end in which a short plate 9d is movable. FIGURE 6 best illustrates the relationship of the arm 82 with the other parts. The short plate 91 is interposed between and in contact with the lower end of the valve 49 and the top curved surface 93 of a spring loaded valve 94. The latter acts to control ports 96 in a sleeve `assembly 98. The ports 96 communicate with an air vent or exhaust 100 defined in the sleeve assembly. A ,coil

spring 102 assures contact between the plate 91 and the valve 94. Stifening flanges 104 and 106 extend the full length of the arm 82, the latter being bifurcated as previously stated and the two ends of the arm 82 are pivotly held in notches of upstanding legs such as the leg 97 seen in FlGURE 6. The short plate 91 is also flanged at both sides to lend stiffness and it is apertured in its top for the reception of the end of one leg of a U-shaped piece 110 as well as a U-shaped spring member or C-spring 112. One end of the latter is retained in a notch 114 of the piece 110 and the other bears against an inner edge of the plate 91. The opposite inner edge of the plate 91 engages a lip 116 integral with the arm 82 and is adapted to pivot thereon. Two legs such as the leg 97 are integral with the U-shaped piece 110 which is held in place by screws such as the screw 111.

The air vent assembly 118 is shown in FIGURE 3 as mounted in a bore 120 formed in the pump casing part 54 to connect the fuel chamber 68 with a vent 122 leading to the atmosphere. The assembly 118 includes a plunger 124 biased away from a port 126 by a spring 128. A needle 125 integral with the plunger controls the port. A clearance around the plunger 124 is adequate to permit air to escape but liquid will close the vent.

Two Z-shaped passages 130y and 132 (FIGURE l) constitute fuel inlet and outlet passages respectively, each communicating with the fuel chamber 68 and controlled by a valve 131 or 133. These Valves are similar. In valve 133 a conical head bolt 134 is fixed to a ported member 136 with a rubber washer or disc 138 movable by fluid pressure to an open position against the conical head and to a closed position as shown in the drawing. Line 16 connects with the passage 130 and a line 139 connects the passage 132 with the accumulator A. Springs 139 and 141 are employed to urge the diaphragm 58 downwardly.

Only one outside fastening bolt 140 is shown in the drawings. It is shown in FIGURE 2 holding a plate 142 to the pump with a gasket 144 interposed but it will be appreciated that a number of such bolts are used to hold the casing parts of the pump P and the accumulator A together.

The block member 24 with a portion of its associated elements has been referred to above in connection with the accumulator A. The latter includes two main casing parts 160 and 162 which cooperate with a diaphragm 164 interposed between them to define the air chamber 34 above the diaphragm and a fuel chamber 166 below the diaphragm. The latter is strengthened by a reinforcing plate 168 attached to it conventionally.

A multiport plate 170 is retained in the part 162 for introducing fuel to the chamber 166 by way of the line 139 and a threaded inlet 172. A similar plate 174 is employed by means of which `fuel may be discharged from the accumulator A by way of a threaded outlet 176 and a conduit (not disclosed) to the fuel injection system of an engine.

The casing part 160 of the accumulator has a recess 17 8 in its top close to a central cylindrical recess 180. The latter is in registry with the recess 30 of the block 24 and extends from the diaphragm 38 to the chamber 34. The recess 178 is larger in diameter and a wall thereof is apertured as at 182 and 184 also to communicate with the chamber 34. The diaphragm 38 traverses the recess 178 and separates the latter from a registering recess 186 dened by the block 24. The recess 186 is vented as at 188. A stem 190 is fixed to the diaphragm 38 by means of nuts 192 and 194 and two opposed backing plates 196 and 198. The lower end of a coil spring 200 is retained on the backing plate 198. The upper end is retained by a member 202 which in turn is positioned by the rounded end of an adjustment screw 204. The stem 190 extends through the aperture 184 and bears an annular groove 206 receiving the forked end 208 of an arm 210 extending from the valve 36 and located in the air chamber 34.

The valve 36 is adapted to slide Qn e bolt 212 (FIG-v URE 5) depending from the top wall of the casing part 54. A spring 214 urges the valve 36 upwardly into closing contact with not only the port member 32 but a second port member 216 which leads to the atmosphere. Discs 218 and 220 of plastic are retained on the valve 36 to present resilient valve seats. The arrangement is such either of the port members 32 and 216 may serve as a pivot for the arm 210 with the result that the other may be opened.

The bottom end of the cylindrical recess 180 (FIGURE l) is restricted at 222 with the formation of an annular shoulder 224 on the casing part 160. Two relatively slidable and telescoping parts 226 and 228 are retained by the recess 180 and a spring 230 urges the part 226 up against the diaphragm 38 and the part 228 down against the shoulder 224. With the part 228 down against the shoulder 224, the part 226 will not not push the diaphragm 38 against the open end of the part member 40 because of a stop pin 232 engaging the end wall of a slot 234 formed in the part 226.

A partition member 236 with a frusto-conical wall 238 is fixed within the casing part of the accumulator A to determine the upper limit of motion for the diaphragm 168. It is apertured at 240 to increase the elective volume of air in the interest of increasing uniformity o pump action by the accumulator A.

In operation, air is supplied under preselected pressure from the tank 12 to the passages 26 and 28 (FIGURE 4) of the block 24. With the parts positioned as shown in the drawings, that air has entered by way of the ported member 32 and the valve 36 into the air chamber 34 of the accumulator A and forced fuel from the now substantially empty chamber 166 to the engine by way of the ported plate 174. The pressure of the air in the chamber 34 determines the pressure of the fuel delivered to the engine. It should be remembered that the apparatus is so designed that the fuel capacity of the accumulator A is much greater than that of the pump P so the diaphragm 164 moves slowly during discharge in its downward travel to attain its position shown. The air pressure in the chamber 34 also acts in the recess 178 (FIGURE 1) against the spring 200. The loading of the latter def termines the air pressure in the chamber 34 and the pressure of fuel as discharged to the engine. An increase of the air pressure in chamber 34 to overcome the spring loading will tilt the valve 36 (FIGURE 5) about the ported member 32 and vent the chamber through the ported member 216. A decrease will cause expansion of the spring 200 and tilt the valve 36 in the other direction and about the ported member 216 to open the ported member 32 and admit more air to the chamber 34. Screw 204 is therefore seen to be a means for increasing or decreasing the fuel discharge pressure to the engine. Under stabilized conditions, the spring 214 will cause the Valve 36 to close both ported members 32 and 216.

The diaphragm 164 should now be raised and the accumulator chamber 166 be quickly filled with fuel under pressure to avoid any interference with engine operation. This is done by a momentary increase of air pressure in the chamber 34 due to the diaphragm reaching its lowest position, tilting the valve 36 and opening the vent afforded by the ported member 216 and closing the ported member 32, these actions being abetted by the action of the pump P forcing the diaphragm 164 upwardly.

To initiate a cycle of operation of the pump P, the diaphragm 38 of the accumulator A will be clear of the ported member 40 thereby permitting air from the tank 12 to enter the passage 42 in the block 24 and by Way of the line 44 to enter the bore 46 (FIGURE 2) of the pump P. The valve plunger 49 will be in its down or open position permitting air to enter the chamber 48. The diaphragm rises quickly and fuel trapped in the chamber 68 is forced to flex the disk 138 (FIGURE 1) downwardly and be forced through the line 139 into the chamber 166 of the accumulator A. As the relative capacity of the pump P is small, one upward thrust of the pump diaphragm 58 against the springs. 139 and 141 displaces the accumulator diaphragm 164 only a small increment of the full range of movement of the latter.

When the pump diaphragm has reached its top position, the shoulder portion 80 will move that end of the arm 82 upwardly, the latter pivoting about the notches in the vertical legs 97. Due to the over-centering device with its C-spring 112, the valve plungers 49 and 94 will be quickly shifted upwardly to close the ports 51 and open the vent port 100 as in FIGURE 2. With removal of air pressure from the chamber 48, the action of the low pressure pump 14 and the springs 139 and 141 will cause the chamber 68 to refill with fuel. When the latter is full, the shoulder 78 will trip the over-centering device and shift the valve'plungers 49 land 94 downwardly to open the ports 51 and close the vent port 100. As a result, the pump P will have gone through one cycle of operation and the accumulator diaphragm will be moved upwardly another increment, the accumulator chamber 166 all the while being a high pressure source of fuel supply for the engine. Any air or vapor present in the pump chamber 68 will be vented by the Valve assembly 118.

After a series of cyclic movements olf the pump P, the accumulator diaphragm plate 168 will eventually contact and upwardly force the member 228 and cut o the air supply being introduced by the ported member 40 to the line 44 and the pump P. Action of the pump P will cease `although its fuel pressure within the chamber 68 is retained due to the one-way action of the admission valve 131. The several quick cyclic movements of the pump diaphragm 58 are not repeated until the accumulator chamber 166 has again emptied.

The spring 128 (FIGURE 3) in the vent valve assembly 118 is strong enough to hold the valve open when vapor or air is flowing into the pum-p chamber 48 but weak enough to allow the valve to close when liquid reaches the valve during a pumping stroke.

The apparatus is such that, if installed on an automobile, the accumulator A may be mounted at any desired point on the car without consideration of the pump P location. Also, the pump P functions freely Iand with a frequency, determined by the time required to iill and empty itself, until the accumulator A holds a fuel quantity preset as full-at which time the accumulator acts to stop the pump P. The latter then stands at rest until the accumulator A empties and opens the air supply to the pump P again to initiate the yrelatively high cyclic operation frequency of the latter.

I claim:

1. Pneumatic pumping `apparatus comprising an accumulator Iwith a chamber of high liquid uid capacity and a pump with a chamber of low liquid fluid capacity, each of said chambers being partially defined by a pres- =sure-actuated diaphragm, a low pressure source of said liquid uid communicating with said accumulator chamber by way of said pump chamber, a high pressure source of a second uid, connections from said latter source to said accumulator and pump to actuate the diaphragms of said accumulator and pump, and said connections includ- 6 ing valve means actuated by said accumulator and pump diaphragms to control ow of said second fluid through said connections whereby the cyclic operational frequency of said pump is high relative to that of said accumulator.

2. Pneumatic pumping apparatus comprising an accumulator of large capacity and a pump of relatively small capacity as two units, each of said units having a liquid chamber and an air chamber separated by a diaphragm, separate pressurized sources of supply for liquid and air, pneumatic connections from said air source to the air chambers of said units in series, fluid connections from said liquid source to the liquid chambers of said units in series, air valve means in said pneumatic connections including a pressure-operated valve in said accumulator and an over-centering device in said pump air chamber for controlling the actuation of said pump diaphragm, one-way valve means in said pump for controlling liquid How through said fluid connections, and the said pressure-operated valve in said accumulator being arranged to be actuated during extreme positions of said accumulator diaphragm to shift during each ycycle of accumulator operation for effecting a series of cyclic operations of said pump.

3. Pneumatic pumping apparatus as set forth in claim 2, the said pressure-operated Valve in said yaccumulator including a spring, the loading of said spring being eiective to determine the maximum pressure of air and liquid in said units.

4. Pneumatic pumping apparatus as set forth in cla-im 2, the said source of supply for yair being under high pressure, the said source of supply for liquid being under relatively low pressure, and the pressure of air in the air chamber of said accumulator determining the liquid discharge pressure of the latter.

5. Pneumatic pumping apparatus comprising an accumulator unit of large capacity and low cyclic operational -frequency and a pump unit of small capacity and high cyclic operational frequency, each of said units having a l-iquid chamber, an air chamber, and -a diaphragm separating the two chambers, a =high pressure air supply source, a low pressure liquid supply source, pneumatic connections leading from said air supply source to said accumulator and then to said pump, iluid connections from said liquid supply source to said pump and then to said accumulator, air valve means in said pneumatic connections including a pressure-'operated valve in said accumulator and an over-centering device in said pump air chamber for controlling the actuation of said pump diaphragm, one-way valve means in said pump for controlling liquid flow through said iluid connections, and the said pressure-operated valve in said accumulator being arranged to be actuated during extreme positions off said accumulator diaphragm to shift during one cycle of accumulator operation for effecting a plurality of cyclic operations of said pump.

6. Pneumatic pumping apparatus as set forth in claim 5, the said pressure-operated valve in said accumulator being adjustable to determine the liquid discharge pressure of said accumulator.

No references cited.

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