US2041717A - Pumping apparatus - Google Patents

Description

May 26, 1936. R. E. LAMBERTON 2,041,717

PUMPING APPARATUS Filed NOV. 27, 1954 Patented May 26, 1936' UNITED STATES PATENT OFFICE PUDIPING APPARATUS Application November 27, 1934, Serial No. 755,014 13 Claims. (01. 2so -2s'),

My invention relates to pumping apparatus for compressible fluids, and, from another aspect, to improved unloading means for such pumping apparatus.

When a multi-stage compressor is provided with a total closure intake unloader for the low pressure cylinder and unloads the high pressure cylinder by opening and maintaining open the inlet valves of the latter, there is a tendency for the intercooler pressure gradually to build up, due to leakage past the intake unloader valve and absence of removal of air from the intercoolerby the high pressure cylinder; and therefore there is a periodic popping of the safety valve which is provided on the intercooler, which is annoying and at times undesirable. If, however, means can be provided for venting the intercooler at such a rate that a moderate pressure may still be maintained therein, while avoiding the building up of an excessive pressure, this would be desirable; and from one aspect my invention consists in the provision of improved meansfor accomplishing this function.

An object of my invention is to provide an improved pumping apparatus. Another object of my invention is to provide an improved multi stage pumping apparatus having improved unloading means. Still another object of my invention is to provide an improved arrangement for maintaining intercooler pressure within desired limits during the unloaded operation of a multistage compressor. Yet another object of my invention is to provide an improved automatically- Fig. 1 is a side elevational view of a multistage compressor arranged in accordance with the illustrative embodiment of my invention;

Fig. 2 is a vertical section taken on line 2-2 of Fig. 1;

Fig. 3 is a fragmentary sectional view through a portion of a high pressure cylinder unloading means; and

Fig. is a horizontal section showing details of construction of the intake type unloader casing.

From the drawing it will be noted-that the compound compressor l shown has a frame 2, a drive shaft 3, a flywheel 4 driven by suitable driving connections, including herein a belt 5 of which a portion only is shown, the crankshaft 3 serving to actuate the pistons (not shown) in the low pressure cylinder 6 and in the high pressure cylinder I. The low pressure cylinder 6 discharges through a connection 8 to an intercooler 9 provided with a suitable pop valve l8; and from the intercooler the cooled and partially coinpressed fluid passes through a connection H to the high pressure cylinder 1, after a further compression in which it is discharged through a discharge line l2 to any suitable point of use.

' The low pressure cylinder 6 receives air through 22 adapted to close the opening through the 20 web l9 and a portion 23 adapted to close the opening through the web 20 is reciprocable in the casing l-i. Valve 2| is normally held in open position by a spring 24 acting upon its lower end,

and may be moved to closed position by a plunger 25 25 reciprocable in a cylinder 26 and adapted to be supplied with air through a connection 21 under the control of a pilot valve 28 supplied with pressure from the high pressure discharge line 12 through a connection. When the pres- 30 sure in the compressor discharge line l2 reaches a predetermined desired maximum, the pilot valve 28 operates in a well-known manner to supply fluid through the line 29 and the connection 21 to the space above the piston 25, and thereby 35 as a pump, due to the maintaining open or its 45 inlet valves 32, and is also unloaded, and accordingly there will be no fluid discharged from the intercooler 9 by the high pressure cylinder I; and indeed, should the discharge valves of the high pressure cylinder prove at all leaky, there may be- 50 some return of air from the line I2 to the intercooler. Moreover, in theevent that air leaks past Accordingly, 40

may? build up sufliciently to open the pop valve, with undesirable noise and with some waste of power, and undesirable heating dueto the compression of the air to a higher pressure than is desired in the intercooler.

To avoid the difficulties mentioned I have provided in alignment with the cylinder 26 and mounted within a cover 34 for that cylinder, an

automatic arrangement for venting, as desired, the intercooler. The head 34 contains a pair of alined cylindrical chambers 35 and 36 connected by a passage of reduced cross-section 31 whose opposite ends are surrounded by conical seats respectively numbered 38 and 39. The central passage 31 is communicable through a lateral passage 40 controlled by an adjustable needle valve 4| with a. passage 42 which opens into the space IB'within the intake closure valve casing l4, and accordingly any noise from air flowing outward through the passage 42 will be muflied by the air cleaner Within the chambers 35 and 36 there are arranged respectively an end seating valve 44 and a plunger 45, each of which has a stem-extending towards the other, which stems are respectively numbered 46 and 41, and which are of such length that the valve and plunger, each of which is beveled to cooperate with one of the conical seats, can not both seat at the same time. A spring 48 normally maintains valve 44 seated and plunger 45 oil of seat 39. The valve 44 is provided with a longitudinal groove 53 so that when it is unseated fluid may flow longitudinally along it. The chamber 49 above the valve 44 is connected by a connection 50 with any suitable point between the low pressure cylinder discharge valves and the high pressure cylinder inlet valves, herein to the discharge line 8 from the low pressure cylinder. A passage 5| formed in a threaded plug 52 which limits the downward movement ofthe plunger 45, subjects thelower end of the latter continuously to the pressure conditions to which the piston 25 is subjected. Accordingly whenever fluid is supplied to depress the piston 25, fluid also flows through the passage 5| to raise the plunger 45, and because the pressure below the plunger 45 is higher than the pressure above the valve 44, the latter is unseated, and

communication is established between passage 59 and passage 42. The valve 4| is preferably adjusted in such manner as to maintain a pressure in the intercooler suited to the design of the compressor, the pressure ranging from 30 lbs. in compressors having a relatively low overall range of compression to considerably higher pressures as the high pressure discharge pressure rises. Piston 25 and cylinder 23, and piston 45 and cylinder 36 will be noted to constitute alined, reversely acting servo motors having communicating cylinders.

The mode of operation of the invention will be very readily understood from what has been already said. When the compressor discharge pressure rises to the desired maximum value, the

pressure conducted through the line 29 and acting upon the pilot mechanism 28 causes the latter to admit pressure simultaneously to close the valve 2| and to open the inlet valves- 32. The compressor is therefore unloaded and while pressure might tend to build up in the intercooler due to leakage, as previously explained, there will be no pressure discharged from the intercooler by the high pressure cylinder. The pressure in the intercooler will, however, be prevented from building up to too high a value, because as the plunger 25 closes the valve 2|, the plunger 45 simultaneously will unseat the valve 44; and a leak connection will thus be opened from the line 8 which communicates with the interior of the intercooler, the air from the latter venting through the passage 50, chamber 49, through the groove 53, passage 31, lateral passage 40, past the needle valve 4|, through the passage 42, into the space l6 and thus escaping to the atmosphere. The intercooler pressure will remain substantially whatever is fixed by the setting of the valve 4|; and the setting of this valve will be determined, by observation, substantially merely to ofiset the rates of fluid supply into the intercooler by leakage back from the line I 2, and due to leakage past the closed intake valve 2 I. When the compressor is to be loaded again due to drop in discharge line pressure, the pressure above the piston 25 and below the piston 45 will be simultaneously vented; and the valve 44 will close the leak connection simultaneously with the opening of the intake closure valve 2|.

It will be evident that I have provided a very simple and efiective arrangement for maintaining intercooler pressure at a desired value during normal unloaded operation of the compressor. It will be obvious that the arrangement is capable of application to portable compressors as well as stationary'compressors, and usable with any arrangement. of unloading in which an intake is closed to a lower stage cylinder and discharge from an intercooler is precluded by virtue of the type of the unloading apparatus used for the next higher pressure stage cylinder. The apparatus will be noted to be simple, efiective, adjustable to different conditions and wholly automatic in operation. 7

While I have in this application specifically described one form which my invention may assume in practice, it will be understood that this form of the same is shown for purposes of illustration, and that the invention may be modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is 1. In combination, a multi-stage compressor having anintercooler, an intake closure type unloader for the low pressurecylinder, an unloading apparatus for the high pressure cylinder effective to interrupt the discharge of pressure from the intercooler by said high pressure cylinder, and means for simultaneously providing a controlled venting of the intercooler pressure.

2. In combination, a multi-stage compressor having an intercooler, an intake closure type unloader for the low pressure cylinder, an unloading apparatus for the high pressure cylinder effective to interrupt the discharge of pressure from the intercooler by said high pressure cylinder, and means governed by compressor discharge pressure for effecting operation of said unloading means, and means also governed by compressor discharge pressure for simultaneously providing a controlled venting of the intercooler pressure, said last means and a portion of said unloading.

equipment each including a valve actuating plunger, said plungers arranged coaxially.

5. In combination, a multi-stage compressor having an intercooler, an intake closure type unloader for the low pressure cylinder, an unloading apparatus for the high pressure cylinder effective to interrupt the discharge of pressure from the intercooler by said high pressure cylinder, means for effecting operation of said unloading means,

and means for simultaneously providing a controlled venting of the intercoolerpressure including a relief valve mounted upon said intake type unloader and opened when the latter is closed.

6. In combination, a multi-stage compressor having an intercooler, an intake closure type unloader for the low pressure cylinder, an unloading apparatus for the high pressure cylinder effective to interrupt the discharge of pressure from the intercooler by said high pressure cylinder, means .;for effecting operation of said unloading means,

and means for simultaneously providing a controlled venting of the intercooler pressure including a relief valve mounted upon said intake type unloader and moving in the same direction as the latter to efiect closure.

7. In combination, in a multi-stage compressor, high and low pressure cylinders and an intercooler, an intake closure unloader for the low pressure cylinder including a servo motor cylinder and piston, means for interrupting pumping by the high pressure cylinder, and intercooler venting means including a second servo motor cylinder and piston coaxial with t e first-mentioned servo motor cylinder and piston.

8. In combination, in a multi-stage compressor, high and low pressure cylinders and an intercooler, an intake closure unloader for the low pressure cylinder including a servo motor cylinder and piston, means for interrupting pumping by the high pressure cylinder, and intercooler venting means including a second servo motor cylinder and piston coaxial with the first-mentioned servo motor cylinder and piston, said servo motor cylinders freely communicating with each other.

9. In combination, a multi-stage compressor having high and low pressure cylinders and means connecting the discharge of the latter to the intake of the former, intake closure unloadin means for the low pressure cylinder, unloading means for the high pressure cylinder interrupting when effective the pumping action thereof, and

means for discharging fluid from said connecting means while said unloading means are effective at at least as low a pressure as normally prevails in said connection during pumping.

10. In combination, a multi-stage compressor having high. and low pressure cylinders and means connecting the discharge of the latter to the intake of the former, intake closure unloading means for the low pressure cylinder, unloading means for the high pressure cylinder interruptmg when effective the pumping action thereof,

and means actuated concurrently with said unloading means for discharging fluid from said connecting means while. said unloading means are effective.

11. In combination, a multi-stage compressor having high and low pressure cylinders and means connecting the discharge of the latter to the intake of the former, intake closure unloading means for the low pressure cylinder, unloading means for the high pressure ylinder interrupting when effective the pum ping action thereof, means for discharging fluid from said connecting means while said unloading means are effective, and common pilot means for said unloading and fluid discharging means.

12. In combination, a multi-stage compressor having high and low! pressure cylinders and means connecting the discharge of the latter to the intake of the former, intake closure unloading means for the low pressure cylinder, unloading means for the high pressure cylinder interrupting when efiective the pumping action thereof, means for discharging fluid from said connecting means while said unloading means are effective, and common controlling means governed by compressor discharge pressure for said unloading and fluid discharging means.

13.In combination, a multi-stage compressor having high and low pressure cylinders and means connecting the discharge of the latter to the intake of the former, intake closure unloading means for the low pressure cylinder, unloading means for the high pressure cylinder interrupting when effective pumping action thereof, means for discharging fluid from said connecting means during unloaded operation of the compressor, and a pilot valve responsive to compressor discharge pressure "controlling supply and venting of com-

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