US2239147A - Variable delivery pump with multiple pressure control - Google Patents

Description

April 22; 1941.

WIERNST ET AL VARIABLE DELIVERY PUMP ,WITH EULTIPLE PRESSURE CONTRbL original Fild Aug. 1 1938 ZSheejs-Sheet l April'22,-1941. w.- ERNST ETAL 2,239,147

VARIABLE DELIVERY uur WITH EULTIFLE PRESSURE. CONTROL Original Filed Aug. 16, 1938 2 Sheets-Sheet 2 TIME Swncu n fig fin INVENTORS WALTER Se/var )4 70/? adv/aw W @12- A TTORNE V5 Patented Ar. 22, 194i VARIABLE DELIVERY PUMP WITH MULTIPLE PRESSURE CON TBOL Original application August 16, 1938,, Serial No. r 225,155. Divided and this application August 28, 1939, Serial No. 292,268

9 Claims.

This invention relates to pumps and, in particular, to variable delivery pumps.

One object of this invention is to provide a hydraulic press circuit for controlling the pressing pressure exerted by the platen by controlling the pressure at which the shift ring of a variable delivery pump is caused to move to its neutral or zero delivery position.

Another object is to provide a hydraulic press circuit, wherein the variable delivery pump is provided with a multiple piston servomotor with different areas on the pistons, and means for selectively directing the pressure fluid from the press cylinder to these areas so that the pump flow controlling member or shift ring will be moved to its neutral or zero delivery position at one of a series of selected pressures, depending upon which of the servomotor piston areas is ex-' Figure 1 is a diagrammatic view, mainly in section, showing a complete hydraulic press operating circuit including this invention. I

Figure 2 is an enlarged diagrammatic view, mainly in section, showing that part of the circuit of Figure 1 for applying diiferent pressures to the press plunger at different periods of time by means of a multiple pressure servomotor pump control system. 1

General arrangement In general, this invention consists of a variable delivery pump with a multiple piston servomotor for moving the pump flow-control member or shift ring to its neutral position when pressure is applied to these different areas, so that the pump is adapted to deliver a plurality of different pressures, depending upon which of the piston areas is exposed to the pressure fluid from the pressing cylinder to shift the pump flow-control member to its neutral position. The action of this multiple servomotor piston, as shown in detail in Figure 2, is opposed by an adjustable spring. V The shifting from one piston area to another is performed by a manual valve, cooperating with a time-responsive valve. The time-responsive valve system consists of a manually operated four-way valve having the supply of air controlled by a solenoidal valve, the solenoid being controlled in turn by a time switch. In this manner the pressure delivered by the pump is of a predetermined degree for a predetermined period of time, after which the valves are shifted so that the servomotor moves the flow-control member to cause the pump to deliver a different predetermined pressure for an additional period of time.

Press construction Referring to the drawings in detail, Figure 1 shows diagrammatically in vertical section a hydraulic press having a bed l0 and head H, interconnected by side members or uprights l2 at interlocking dove-tail portions l3 and M, respectively. Mounted upon the press head H is a surge tank l5 for containing and supplying the operating fluid utilized in the circuit. The press head I I contains a main'cylinder bore l6, one end of which serves as a press-advancing chamber l7, and the other end l8 has a press-retracting chamber, these being on opposite sides of the piston head [9 of the main plunger 20. Thus, the main plunger 20 is a double-acting plunger, reciprocating in the cylinder bore [6.

Opening into the press-advancing chamber ll is a port 2 1, providing communication with the interior of the surge tank I5. Mounted in the port 2| is a double-acting surge valve 22, of the type disclosed in the patent to Walter Ernst, No. 1,892,568, of May 1, 1934. The details of this surge valve 22 form no part of the present invention, and its function is as a check valve, which opens when the main plunger 20 starts on its downward stroke under the influence of gravity, so as to permit the rapid traversing of the main plunger 20. The surge valve 22 is provided with a hydraulic motor within the casing portion 23 thereof, this being connected by the conduit 2% with the return chamber l8 beneath the main piston head 19, so as to forcibly open the surge valve 22 and keep it open during the retraction stroke 7 of the main plunger 20. This action, as described in the above-mentioned patent, permits the fluid to pass directly from the chamber ll, through the port 2 I, back into the surge tank l5 without traversing the remainder of the hydraulic circuit. Attached to the main plunger 20 is a platen 25 which moves up and down between the press side members l2 and is guided thereby. The platen 25 is provided with two cam portions 26 and 21 for operating certain valves at predetermined positions upon the stroke of the platen 25. Sur- Multiple pressure pump control sub-circuit The multiple pressure pump-control sub-circuit is shown in the upper right-hand corner of Figure 1, and in more detail in Figure 2. Thispart of the circuit isemployed for applying diiierent pressures to the main plunger 28 at different portions of its stroke, for different periods of time. The sub-circuit consists of a variable delivery radial piston pump 38, shown in Figure 1 as mounted upon the side of one of the press uprights I2. Ordinarily, however, this pump 38 is most conveniently mounted upon the head of the press. The pump 38, insofar as its actual pumping mechanism is 'concemed, is well known to those skilled in the hydraulic art, and 'is of the type having radial pistons and cylinders with variable strokes, as regulated by the shift ring for shifting the eccentricity of the axis of rotation of the cylinder barrel with respect to the secondary rotor for actuating the pistons. Such a pump is shown in the Ernst Patent No. 2,021,354, of November 19,1935.

The pump 38 consists of a central casing 3| having therein the pumping mechanism, together with the shift ring for varying th delivery of the pump. This casing 3| is closed by end plates 32, on one of which are mounted the pressure and suction connections "and 34, respectively. The pump 38 is driven by any suitable means,.such as an electric motor (not shown). Coaxial with the main pump 38 and driven by the same motor from the shaft thereof, is a slippage pump 35, of any suitable type, such as of the gear type, for providing the low pressure service of pumping slippage fluid from the slippage tank 36, back to the surge tank I5 by means of the conduits 31 and 38, respectively (Figures 1 and 2) The slippage tank 36 is connected by the line 39 to the pump casing 3| for the purpose of collecting leakage therefrom, and also by the line 48, to the port 4| immediately above the packing 28 and opposite the perforated drainage ring 42. This ring 42 provides for slippagev past the packing 28 from the main cylinder chamber I8. v

Mounted upon one side of the main pump casing 3| is a casing. 43 having a bore. for telescopically receiving a sleeve 45 containing a coil spring 46, abutting the wall 41 at one end of the sleeve 45 and the plate 48 at the other end within the casing 43. Passing through the plate 48 is the pump control rod 49, having a threaded portion 58 thereon engaged by a nut 5|, to which is secured a, hand wheel 52, as by the key 53. Arranged between thenut 5| and the end wall 4! of the sleeve 45 is a ball thrust bearing 54.

Also mounted upon the threaded portion 58 of the control rod 49 is a locknut 55, in the form of a secondhand wheel, whereas a nut 56, threaded upon the end of the control rod 49, serves as a retaining nut to retain the parts in position.

The control rod 49 is secured at its inner end to the pump flow-control member or shift ring (not shown), while similarly. mounted upon the other end thereof is the servomotor rod 51, carrying thereon the stepped servomotor piston, generally designated 58, reciprocable within, the stepped bore, generally designated 59, ,of the servomotor casing 68 (Figure 2). The servomotor casing 68 is mounted upon the side of the pump casing 3|, in a manner similar to the easing 43. The end of the bore 59 in the casing 68 is closed by'an end plate 6| by means of the cap screws. 62. I

The stepped piston 58 is provided with annula piston areas 63, 64 and 65, formed between the different diameter portions 66 and 61, 61 and 68 and 68 and 69, respectively.. The smallest piston area 63 reciprocates within the small diameter bore portion I8, the intermediate piston area 64 within the intermediate bore 'II, and the large piston area 65 within the large bore portion I2. These bore portions I8, II and I2 Iorm' parts of the stepped bore 59. Adjacent the respective piston areas 63, 64 and 65 their bores I8, 'II and I2 are widened out in the annular chambers I3, I4 and I5, respectively. Communicating with these chambers are ports I6, TI and I8, respectively connected to conduits I9, 88 and 8|.

The conduit 19 contains a choke 82 for the purpose of preventing too sudden a shifting of the stepped piston 58 in. response to a sudden change of pressure. The stepped piston. 58 is held in position by a collar 83, secured upon the rod 51 by the end member 84. The conduit 19 is connected to the conduit 85, leading to the passageway 86 opening into the press-advancing chamber I'I of,the main cylinder bore I6. 4 The conduits 88 and 8|, however, lead to a manually operated four-way valve, generally designated 81, at the ports 88 and 89 thereof, respectively. These ports lead into a bore 98 having therein a valve rod 9| with spaced heads 92 and 93. The valve rod 9| emerges through'plugs 94, one plug being mounted in the valve casing 95 and the other in the end plate 96 thereof. The valve rod 9| terminates. in a handle 91 for the manual manipulation of the valve. The valve bore 98 is provided with annular chambers 98 and 99, adjacent the ports 88 and 89, additional end chambers I88 and IN being likewise provided and having ports I82 and I83 connectedto a discharge conduit I84 leading to the slippage tank 36. The fifth chamber I85 has its port I86 closed by a plug I81.

Pressure fluid is supplied to the conduit 88 by means of a conduit I88, from an air-operated four-way valve I89 having the valve portions of similar construction and therefore similarly designated as in the -four-way valve 81, with the distinguishing numerals 98 to I81, respectively, The :valve rod 9| of the valve I 89, however, terminates at one end in an extension II8 surrounded by a coil spring III, engaging a collar'II24Zspured to, the valve rod 9| as at H8.

downwardly until the collar 2 engages the upper plugs9l The coil spring III at its upper end engages the .inner wall 01' a cap II 4, secured by the screws H5 to the casing of the valve I89. Communicating with the 'ports I82 and I03 is the conduit II 6, leading downwardly to the slippage tank 36 ,(Figure 1). On the lower end of the valve rod 9 I is mounted a piston head II 1, reciprocable within the bore H8 or an air cylinder 'II9, mounted upon the lower end of the valve casing 95*. This bore 8 is provided with breather ports I28, whereas the opposite end of the air cylinder I I9 is provided with a port I2 I, to which isconnected the conduit I22 leading conduit I31.

former leading directly to the electrical supply line I29, whereas the latter leads to the electrical supply line I28 by way of the time switch I30 and line I3I (Figure 2). The time switch I30 is of any conventional type, and operates a predetermined time after its energization through the lines I3I and I32 to change the energization of the solenoid I25 and to shift the valve rod I22 of the valve I23, opening the'conduit I22 to the compressed air conduit I3d, With the switch I3I closed, the time switch I30 starts when the valve I40 is shifted to commence a pressing stroke, the motion of the valve I closing a switch I40 through the stroke of the plunger I40 but with the switch I3I open, the time switch I30 starts by the closing of the pressure switch I33 upon the attainment of a predetermined low pressure during the pressing stroke. The variable delivery pump 30 draws in fluid from the surge tank I by way of the conduit I35, and discharges pressure fluid through the The globe valve I36 and the check valve I30 merely serve to prevent the escape of fluid from the surge tank I5 whenthe pump 30 is disconnected for repairs, or other purposes.

In the operation of the multiple pressure subcircuit shown in Figures 1 and 2, the operator piston head III upward.

rotates the hand wheel 52 to adjust the com- I pression of the spring 46 to the desired amount suitable for opposing the action of the stepped piston 58, and locks it by turning the locknut 55. The spring 48 tends to force the flow-control member or shift ring of the pump toward an eccentricposition relatively to the pump'cylinder barrel, thereby putting the pump on stroke I to deliver pressure fluid. When the stepped piston 58 is supplied with pressure. fluid of a suficient degree to its stepped piston areas 83, 84

'or 85, it tends to overcome the force of the spring 25. When a suflicient pressure has thus been built up to overcome the force of the spring, the pump shift ring or flow-control member is moved back to its neutral or no delivery-position, compressing the spring I8. Thus, with a given pressure supplied'to the stepped piston 50, a lower pressure will be required to overcome the spring force and move the pump to its no delivery position when the pressure is admitted to the larger areas thereof than to a smaller area.

When the pump 30 is started in operation, it

delivers pressure fluid through the line I31, to

the upper chamber II of the main cylinder bore I0, and the main piston head I0 starts downwardly on its pressing stroke in response to the shifting of the main control valve, generally designated I80 (Figure 1). The platen ,25 moves downwardly under the influence of gravity upon its weight, and opens the surge valve"2;2, thereby drawing fluid from the surge tank I15into the 60 upper chamber Il. When the platen 25 ,encounters the workpiece, or other mechanism operated upon, pressure develops within the upper chamber II of the main cylinder bore It, this pressure being transmitted through the passageway 86 and conduits 85 and I0, through the choke 82 to the chamber I3 within the servomotor casing 80, acting against the small diameter air line I34, through the now 'open valve I23 and line I22, through the port I2I, forcing the The pressure fluid emerges from the valve I00, through the conduit I08, and thence through the conduit and port 'I'I, into the intermediate chamber I I of the servomotor casing 80. Here it acts against the intermediate annular piston area BI upon the stepped piston 58.

At the same time, pressure fluid from the line 80 passes through the manually operated valve 81, which the operator has-shifted'to the right of the position shown in Figure 2 so as to permit this pressure fluid to pass outwardly through the port 89, conduit 8i and port I8, into the upper chamber I5 of the servomotor casing 00. In this manner the pressure fluid coming from the upper chamber II of the main'cylinder bore I8 is transmitted simultaneously to all three piston areas 53, I54 and upon the servomotor piston 58. As a large area is exposed to the action of this pressure fluid, a relatively low I pressure within the chamber II will sufflce to overcome the resistance of the coil spring I6, and shift the flow-control memberor shift ring of the variable delivery pump 30 to its neutral or no delivery position. The pump, therefore, operates at low pressure so long as the pressure is admitted to all three areas of the servomotor piston 58. If, however, it is desired to operate the press at an intermediate pressure, the handoperated valve 81 is shifted to the left, into the position shown in Figure 2. This action closes.

the valve 8! to the entrance of pressure fluid from the conduit 00, and at the same time opens up the upper chamber I5 of the servomotor casing 50 to the discharge line I00, by way of the valve chamber in the hand-operated valve 81, thereby rendering ineffective the upper annular piston area 65'upon the servomotor piston 58.

Meanwhile, of course the time switch I30 has been energized and is running. At the expiration of the period of time for which the time switch I30 is set, the latter changes the energization of the solenoid I25 so as to shift the valve rod I24 and close the valve I23, thereby cutting off the supply of air to the piston III. Accordingly, the valve rod III of the valve I 09 moves downwardly, carrying with it its piston heads 92 and 93, into the position shown in Figure 2. This cuts off the valve I09 from the entrance of pressure fluid from the line 85 and opens the middle chamber I4 to the discharge line H5, so that the fluid from the chamber 14 may flow through the conduits 80, I08 and H6, back to the slippage tank 30. With the upper and middle chambers I5 and I4 of the servomotor casing 60 thus rendered inefiective, the lower chamber I3 and its annular piston area' 53 alone are supplied with pressure fluid. Under these conditions, the pump 30 operates at high pressure since a relatively high pressure is required to be exerted against the annular piston area 83 to overcome the force of the coil spring 36 and to shift the pump flow-control member or shift ring to its neutral or no delivery position. By suitably shifting the handle 97! of the manual valve 87, the operator can selectively apply either a low or an intermediate pressure initially by the pump 30, and follow it up with a high pressure after a predetermined period of time, according to the setting of the time switch I30.

The remaining portions of the circuit shown in Figure 1 are described and claimed in our copending applications Ser. No. 225,155 filed Aug.

16, 1938; Ser. No. 292,269 filed August 28, 1939; and Ser. No. 292,270 filed August 28, 1939.

-It will be understood that we desire to comprehend within our invention such modifications as come within the scope of the claims and the invention. I

Having thus fully described our invention, what 2. In a variable delivery hydraulic pump having a movable flow-control member for regulating the delivery of said pump, yielding means for urging said flow-control member in one direction, a servomotor cylinder having a plurality of chambers, and a servomotor piston connected to said pump flow-control member and having a plurality of piston areas disposed one to each respective chamber, each of said piston areas being adapted to become efiective in one and the same direction.

, 3. In a variable delivery hydraulic pump having a movable flow-control member for regulating the delivery of said pump, yielding means for urging said flow-control member in one direction, a servomotor having a plurality of spaced piston areas for urging said flow-control member in one and the same direction against the thrust of said yielding means the opposite direction, and means for selectively making one or more of said piston areas effective.

4-. In a variable delivery hydraulic pump having a movable flow-control member for regulating the delivery of said pump, yielding means for urging said flow-control member in one direction, a servomotor cylinder having a plurality of chambers, a servomotor piston connected to said pump flow-control member and having a plurality of piston areas disposed one to each respective chamber, each of said piston areas being adapted to become effective in the same direction, and means for varying the thrust of said yielding means.

'5. In a variable delivery hydraulic pump having a movable flow control member for regulating the delivery of said pump, yielding means connected to one side of said flow control member for urging said flow control member in one direction, and a fluid pressure motor connected to the opposite side of said flow control member.

and having a plurality of spaced piston areas,

each of said piston areas being adapted to urge said flow control member in the same direction against the thrust of said yielding means.

6. In a variable delivery hydraulic pump having a movable flow control member for regulating the delivery of said pump, yielding means connected to one side of said flow control member for urging said flow control member in one direction, a cylinder having a plurality of chambers, and a motivepiston therein connected to the opposite side of said flow control member and having a piston area in each chamber for urging said flow control member in the opposite direction, one of said piston areas being adapted to become effective independently of or in combination with another of said piston areas.

7. In a variable delivery hydraulic pump having a movable flow control member for regulating the delivery of said pump, yielding means connected to one side of said flow control member for urging said flow control member in one direction, a motivepiston connected to the opposite side of said flow control member and having a plurality of annular piston areas, each of said areas being adapted to become effective for urging said flow control member in the opposite direction against the thrust of said yielding means, and a cylinder having a chamber for receiving each piston area.

8. In a variable delivery hydraulic pump having a movable flow control member for regulating the delivery of said pump, yieldingmeans connected to one side of said flow control member for urging said flow control member in one direction, a plurality of piston portions connected to the opposite side of said flowcontrol member, each of said piston portions being adapted to become effective for urging said flow control member in the opposite direction, and cylinder means having a plurality of chambers disposed one to each respective piston portion.

9. In a variable delivery hydraulic pump having a movable flow control member for regulating the delivery of said pump, yielding means connected to one side of said flow control mem-

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