US3713755A

US3713755A - Pumping device

Info

Publication number: US3713755A
Application number: US00134606A
Authority: US
Inventors: H Scheffer
Original assignee: Harry Krueger GmbH
Current assignee: Harry Krueger GmbH
Priority date: 1970-04-25
Filing date: 1971-04-16
Publication date: 1973-01-30
Anticipated expiration: 1990-01-30
Also published as: FR2090612A5; GB1342011A; DE2020317A1

Abstract

A pumping device having a piston pump and a drive constituted by a thrust-piston motor means actuated by a fluid motive medium, wherein at least one pump is arranged within the motor means.

Description

8 United States Patent 1 Scheffer 1 Jan. 30,1973

1 1 PUMPING DEVICE [56] References Cited [75] Inventor: Harry Scheffer, 4812 Brackwede, UNITED STATES PATENTS.

Germany 496,898 5/1893 Reagan,.1r .;...417/400 [73] Assignee: Harry Kruger GmbH, Westfalen, 3,205,825 9/1965 Kojabashian etal. ..417/400 German y FOREIGN PATENTS OR APPLICATIONS [22] Filed: April 16,1971

809,885 8/1951 Germany ..4l7/400 [21] Appl. No.: 134,606

[30] Foreign Application Priority Data April 25, 1970 Germany ..P 20 20 3172 l Ii 11 I:l l 33 ii] 27 l H1124 a1 I 7 70 l' 0 13 ZE 1.: 32 15/1, 1% We 12 l. ii

Primary Examiner-William L. Freeh Assistant Examiner-R. J. Sher Attorney-Seaman & Beaman [57] ABSTRACT A pumping device having a piston pump and a drive constituted by a thrust-piston motor means actuated by a fluid motive medium, wherein at least one pump is arranged within the motor means.

7 Claims, 4 Drawing Figures PATENTEUJANQO 197s 3.713.755 SHEET 2 0r 3 Q VENTOR BACKGROUND OF THE DISCLOSURE The invention relates to a pumping device having a piston pump and a drive constituted by a piston motor means actuated by a fluid motive medium. In pumping devices to be found on the market, the thrust-piston motor means generally has a relatively large diameter in comparison with the pump. This difference in diameter is caused by the fact that the air pressure available at industrial premises is relatively small, for example 6 kgflcm but on the other hand the pressures to be built up by the pump are larger and in certain circumstances are even required to reach several thousand kgflcm Since in already known devices the sub-assemblies interconnected by the piston-rod of the thrust-piston motor means are arranged in succession, the pumping device has a considerable axial length. The piston-rod makes it necessary to have a sealing system relative to the working chamber of the thrust-piston motor means.

OBJECT OF THE INVENTION The invention aims at the creation of a pumping device which substantially avoids the disadvantages of the known pumping devices, but makes possible operations at the desired transmission ratios.

BRIEF SUMMARY OF THE INVENTION The invention proceeds from the point that in pumping devices driven by a thrust-piston motor means, the effective cross-sections of the pump always take up only a relatively small fraction of the effective crosssections of the compressed-air motor means.

According to the invention, it is envisaged that at least one pump will be arranged within the motor means.

FURTHER FEATURES Such an arrangement on the one hand renders possible a compact mode of construction and the elimination of the thrust-piston rod, and on the other hand the transmission ratios desired are not limited to any substantial degree. If the pump and the thrust-piston motor means are of cylindrical form and the pump is of approximately half the diameter of the thrust-piston motor means, only about one-quarter of the effective surface-area of the thrust-piston motor means will have been taken up for the installation requirements of the pump, since a circular area is a quadratic function of the diameter.

Preferably, at least one piston-rod with bores and valves is fixedly arranged in a casing, and the thrustpiston drive is formed in such a way and displaceably positioned in such a manner on the piston-rod that between the thrust-piston and the piston-rod a pumping space is delimited the size of which is variable by displacement of the thrust-piston along the piston-rod. The thrust-piston therefore concurrently constitutes the movable pumping plunger displaceably borne on the fixed piston-rod of the pump.

In one convenient embodiment, within the pistonrod two bores or ducts are formed within the piston-rod to connect the pumping space and the external space around the casing, and in each of the said ducts a nonreturn valve is located. The non-return valves are so arranged that one duct can be employed as a suction duct, and the other as a delivery or discharge duct.

In a preferred embodiment the piston-rod extends right through the casing and has two sections of differeing diameter, and the thrust-piston consists of at least a pumping plunger and an operative flange.

The pumping device according to a further aspect of the invention is characterized by a valve seat which separates a first and a second valve chamber within the piston-rod, there being positioned on the valve seat a spring-loaded valve body constituting a second valve (the pressure valve), while a spring-loaded valve body constituting a first valve (the suction valve) is located on a valve seat on the bottom of the valve chamber formed in a section of the piston-rod of smaller diameter, the valve chambers in each case being connected to the outside through the bores.

In one preferred form of embodiment, the internal diameter of the plunger is substantially equal to the diameter of the section of the piston-rod of larger diameter, and the first valve chamber is connected through passages with the pumping space.

Since the diameter of the section of piston-rod of larger diameter is substantially equal to the internal diameter of the plunger, in this case a single-acting pump is obtained. If the diameters of the two sections only differ slightly from each other, then the transmission ratio obtained is a particularly high one.

In another preferred form of embodiment, the internal diameter of the plunger is greater than the diameter of the piston-rod section of larger diameter, and a third piston-rod section is provided between the two previous piston-rod sections, the diameter of the third section being substantially equal to the internal diameter of the plunger, the'first valve chamber being connected through passages to the suction space and the second valve chamber being connected through passages to the delivery space, the suction and delivery spaces being separated by the third section of the piston-rod.

In this device, the pump with differential pistons operates with a single action on the suction side and a double action on the delivery side. Utilizing this pump, particularly high transmission ratios can therefore be obtained.

It is recommended that the third section of the differential-piston rod should preferably be formed in one piece with the cross-section of piston-rod having the larger diameter.

It is preferred that at least two sections of piston-rod should be capable of being connected together. Such an interconnected combination renders possible simple assembly of the arrangement.

According to a further aspect of the invention, the casing consists of a first cylinder cover with at least one canister-shaped section, a cylindrical intermediate unit and a second cylinder cover with at least one canistershaped section or a level surface, the admission and discharge of fluid motive medium taking place through apertures in the cylinder covers. The cylindrical intermediate unit defines the working volume of the operative flange of the thrust-piston, while the canistershaped sections serve to accommodate the pump plunger.

Although in many cases it may be desired that the entire pumping device, apart from the apertures to admit and discharge the fluid motive medium, should each have only a single intake and in a single delivery orifice and should otherwise be hermetically sealed, in certain circumstances, when corrosive or otherwise harmful substances which attach the compressed-air motor means are conveyed, it may be necessary for the material being conveyed not to come into contact with the fluid motive medium. It is therefore envisaged that the cylinder covers in the area of the'canister-shaped extensions should be provided with openings and that the working space of the thrust-piston should be sealed between the cylindrical section of casing and the thrust-piston; Leakages between the movable pumping plunger and the fixed piston-rod are able to pass through these openings in the canister-shaped extensions into the open.

One form of embodiment is also conceivable, however, in which the piston-rod extends only into the casing and in which the thrust-piston consists of at least one canister-shapedsection and one operative flange, the pumping chamber being defined by the top surface of the piston-rod and the interior wall of the canistershaped section. With an arrangement of this type, high transmission ratios are not to be expected.

In order to obviate any loss of fluid motive medium from the delivery side to the draw-off side, a seal is arranged around the periphery of the operative flange of the thrust-piston. In order to decrease leakages between the fixed piston-rod and the mobile thrustpiston, the thrust-piston is sealed relative to the pistonrod by one or more seals. The piston-rod is similarly sealed relative to the casing.

In all embodiments it is naturally possible to arrange a plurality of piston-rods in the casing instead of a single piston-rod. The associated plungers may either be formed singly on the thrust-piston, or be in combination. Several pumps can therefore be driven concurrently by one thrust-piston. The size of the remaining effective area of the thrust-piston will depend, in the.

case of a plurality of pumping plungers and piston-rods, on the transmission ratios desired.

It is possible that the piston-rods or their individual sections will be of differing diameters from rod to rod, and/or that the internal diameter of the associated pumping plungers will be of differing sizes. In this way it is possible to arrive at differing pressures and differing amounts conveyed.

It is also possible that the delivery-side coupling of a first pump'may link to the suction-side coupling of a second pump so that, for example, the compression ofa gas under conveyance is possible in stages. Apart from two-stage compression, further stages of compression are also possible.

The reversing arrangement which is required to obtain a reciprocating movement of the thrust-piston in the casing forms no part of the invention, and may be one of the already known reversing arrangements.

BRIEF DESCRIPTION OF DRAWINGS The invention will now be described in greater detail by means of four examples of embodiment, making reference to the accompanying drawings, in which:

FIG. 1 shows a pumping device with a stepped piston and single-acting operation;

FIG. 2 is a view of a pumping device with a differential piston which is single-acting on the suction side and double-acting on the delivery side;

FIG. 3 is a view of a pumping device with two differential pistons which is similarly single-acting on the suction side and double-acting on the delivery side, and

FIG. 4 shows a pumping device according to the invention with a smooth piston.

DETAILED DESCRIPTION The casing 10 of the form of embodiment shown in FIG. 1 of the pumping device consists of an upper cylinder cover 11 and a lower cylinder cover 12 which are attached to a cylindrical intermediate unit 13 'by means of bolts 14. The bolts 14 are merely indicated by a center line.

The cylinder covers 11 and 12 have canister-type extensions between the ends of which a piston-rod, consisting of two

parts

15 and 17, is disposed with the interposition of

seals

16 and 18. The diameter d of the piston-rod section 17 is larger than the diameter (1;, of

the piston-rod section 15.

The piston-rod section 15, with the inter-position of a valve seat 19 and a sealing ring 20, is inserted in a bore 17a in the piston-rod section 17.

The valve seat 19 bounds a valve chamber 15b formed in the upper end of piston-rod 15. At the bottom of the valve chamber there is a valve seat formed on which a valve body 21 is positioned. The valve body 21 is biased by a spring 22 which finds support on one side of the valve seat 19. The bore 17a in valve-rod section 17 alters into a valve chamber 17b bounded by the valve seat 19. In the valve chamber there is a valve body 23 positioned on the valve seat 19. The valve body is biased by a spring 24 which finds support on the end of valve chamber 17b.

The piston-rod section 15 has an axial bore 25 which connects the suction side S of the pumping device with the valve chamber 15b and can be sealed off by the valve body 21. In the area of the valve chamber 15b the piston-rod 15 is provided with radial bores 26. In piston-rod section 17 there is formed an axial bore 27 which connects valve chamber 17b to the delivery side of the pump. The compressed-air piston 28 consists of a pumping plunger 29 and an operative flange 30 appertaining to the compressed-air piston, the two forming a unified piece in the form of embodiment shown here. It is also conceivable that the two component parts of the thrust-piston will be welded together. The thrust-piston 28 is sealed relative to the inner wall of the cylindrical section 13 of the casing 10 by a seal 31 inserted into a groove in the operative flange, so that the lower working volume 32 is separated from the upper working volume 33 of the thrust-piston motor means.

The internal diameter d, of plunger 29 corresponds substantially to the external diameter d of the pistonrod section 17. i

The plunger 29 is sealed as regards piston-rod section 15 by packing 34 and as regards piston-rod section 17 by packing 35. The pumping space 36 of the present arrangement is defined between the inner wall of plunger 29, the terminal annular surface of piston-section 17 and the surface-area of piston-section 15.

In cylinder covers 11 and 12 there are provided

inlet openings

11a and 12a which are connected to air-intake and air-

discharge lines

37 and 38. The doubleheaded arrows shown in FIG. 1 are intended to indicate that by way of each individual line air will be admitted or exhaust air discharged as the occasion demands. As already mentioned hereinbefore, for this purpose any already known reversing arrangements for thrustpiston motor means actuated by fluid media may be employed.

In what follows, the mode of operation of the device according to FIG. 1 will be described. If a pressure is built up through the above-mentioned reversing arrangement in the upper working volume 33 of the thrust-piston motor means, this pressure operates on the surface-area of piston 29 that results from the difference in diameters D (1,. The resulting force gives rise to a downward movement of piston 28 and increases the suction space 36, whose effective surfacearea results from the difference in diameters d, (1,. At the increase in the section space the suction-side valve body 21 lifts off its seat b, and the suction space 36 is filled with the substance that requires conveyance, this taking place through the bore 25 and the passage 26.

If the piston 28 reaches its bottom dead center, then by means of the reversing arrangement. the working volume 33 will be connected by way of line 37 with the exhaust-air outlet, and pressure will be concurrently built up in the working volume 32 by way of line 38. The compressed air will now impinge on the surface of thrust-piston 28 that corresponds to the difference in diameters D d,. The piston 28 moves upward, so that the suction-side space 36 is decreased. The suction valve body 21 alights on the valve seat 15b and closes the suction duct 25. Through the pressure prevailing in the suction-side space 36 the valve body 23 is lifted against the urging of the closure spring 24, with the consequence that the material being conveyed is able to leave the pumping device on the delivery side through'valve chamber 17b and the bore 27. The arrangement according to FIG. 1 is therefore single-actmg.

In the embodiment shown in FIG. 2, the internal diameter d, of plunger unit 29' is larger than the form of embodiment according to FIG. 1, while the diameters D, d and d, are the same. At the upper end of piston-rod section 17 there is formed a flange 17c whose diameter is substantially equal to the diameter d, of the internal space inside the plunger. This flange 17c may also form part of a separate third piston-rod section. In the form of embodiment shown it is, however, constituted in one piece with the piston-rod section 17. The flange 170 is sealed as regards the wall of plunger 29' by packing 39. Since the internal diameter d, is greater than the diameter d; of piston-rod section 17, in the form of embodiment shown a delivery-side space 40 is present which is separated from the suction-side space 36 by the flange 17c and is connected to the valve chamber 17b through passages 41.

The mode of operation differs from the pumping device according to FIG. 1 due to the fact that, during the downward movement of piston 28, not only is the suction-side space 36 increased and filled but at the same time the delivery-side space 40 (whose working surface-area results from the difference d, d is decreased by the stroke, with the consequence that the corresponding amount of substance being conveyed is squeezed out of space 40 through the passages 41 and the bore 27. During the downward movement the pressure valve'body 23 is positioned on the valve seat 19, i.e., the pressure valve is closed.

After a reversal at the bottom dead center, the valve body 21 in the embodiment last described will be located on the valve seat 15a and will be closing off the suction duct S. The substance being conveyed, duly forced from the suction-side space 36, flows when the valve body 23 is lifted partly into the delivery-side space 40 which is increasing during the downward movement of piston 28', but also partly through the bore 27, since space 40 in one terminal position of piston 28' is smaller than space 36 in the other terminal position of piston 28'. The pumping device therefore operates singleacting on the suction side and doubleacting on the delivery side.

In the form of embodiment shown in FIG. 3, the component parts corresponding to the parts in FIGS. 1 and 2 are given the same reference numerals; if the parts diverge in certainfeatures from those previously described, then a double apostrophe will be added a an indicator.

In the casing there is fastened a piston-rod with

sections

15, 10 and 17. Additionally, in the casing there is fastened a second piston-rod with

sections

42 and 43. The

sections

17 and 43 have the flanges 17c and 43c respectively which are described in connection with FIG. 2.

On these two piston-rods, the cylindrical section 29" of the thrust-piston 28" is displaceable, since it is provided with two cylindrical bores Z, and Z In the embodiment shown, the plungers 29 associated with the

individual rods

15 and 17 and 42, 43 are combined to form one component part 29". It is also possible to conceive of arrangements in which the plungers are independently connected to the flange 30". The

bores

25 and 27 not shown in FIG. 3, and the corresponding bores in the piston-

rod

42, 43 define two suction-side couplings S and S and two couplings Dr, and Dr, on the delivery side. The dimensions e,, e and e corresponding to the dimensions d,, d and d of

piston

15, 17 may be different, with the consequence that the pressures built up and the amounts conveyed at the delivery-side outlets Dr, and Dr will be different. The possibility also exists that the delivery-side coupling Dr, may be connected to the suction-side coupling S of the second piston-rod (this link is shown in chain-dotted lines in FIG. 3).

If gases are being conveyed, a two-stage compression will thus be obtained. Given a plurality of piston-rods and a plurality of plungers Z, naturally compression of the gases involving a greater number of stages can be achieved.

The casing of the pumping device according to FIG. 3 differs from the casing according to FIGS. 1 and 2 due to the fact that the suction-side spaces 32" and 33" are sealed, as regards the plunger-associated section 29" of the thrust-piston 28", by packing 44 and 45. In the arrangements according to FIGS. 1 and 2, the leakages occurring at packing means 34 and 35 are fed to working

volumes

32 and 33 and, passing through

exhaust ducts

37 and 38 respectively for the operative medium for the thrust-piston motor means, arrivein the open. This may in many cases be desired, since the pumping device will then have suction-side and delivery-side couplings S, Dr, and will in addition be closed hermetically.

If, however, with the aid of the pump according to the embodiments in accordance with FIGS. 1 and 2, or of the pumps according to FIG. 3, harmful substances are being conveyed which would attack the

thrustpistons

28 or 28" respectively and the reversing arrangement (not shown), then an arrangement according to FIG. 3 is more advantageous. The cylinder covers 1 l and 12" are interrupted by excised

areas

46 and 47, so that the leakages occurring at packing means 34 and 35 can be immediately noticed. In this event the working

volumes

32 and 33" have to be sealed from the outside space around the pumping device by seals 44 and 45. In the embodiment shown in FIG. 3, the effective areas of the thrust-piston motor means, both during the upward and the downward movement, may be ascertained from the difference in diameters D d d being the diameter of the plunger component 29".

Finally, a pumping device in accordance with the invention should be described which is, however, not provided with a stepped piston. In the form of embodiment shown in FIG. 4, there portrudes into the casing a piston-rod 48 made in one piece with the lower cylinder cover 12. The lower cylinder cover has a level outer surface. The thrust-piston 49 consists of a cylindrical part 50 closed at one end and an operative flange 51 provided at the edge of the said cylindrical section, the flange being constituted in this form of embodiment as well in one piece with the canister-shaped part 50.

In the piston-rod are formed two

bores

52 and 53. In the vicinity of the unencumbered end surface 54 there are provided a suction valve chamber 480 and a pressure valve chamber 48b. The valve bodies 55 and 56 and the associated closure springs 57 and 58 are so positioned in the

valve chambers

48a and 48b that, upon the pumping space 59 which is bounded by the terminal surface 54 and the interior wall of the canister-shaped section 50 increasing, the valve body 55 is lifted from its seat, and so the suction duct 52 is opened, and upon a decrease in space 59 the valve body 55 alights on its seat and the valve body '56, against the urging of spring 58, lifts, so that the substance being conveyed and now located in pumping space 59 is able to flow through the delivery-side duct 53 to the delivery-side outlet Dr.

Although in the embodiment according to FIG. 4, in comparison with the differential-piston arrangements according to FIGS. 1 to 3, no large transmission ratio can be achieved, the arrangement according to FIG. 4 also displays the features fundamental to the invention. The pump is arranged within the motor means, the piston-rod has been eliminated, and consequently its sealing system as well. The valves are accommodated in a fixed piston.

Apart from the above-mentioned advantages of the elimination of the piston-rod and of its sealing system and of the extremely abbreviated structural lengthof the assembly overall, the forms of embodiment according to FIGS. 1 to 3 offer the additional advantage that, with a given diameter D for the thrust-piston motor means and a prescribed diameter d for section of the differential piston-rod, meretliy through an alteratron in the internal diameter d,'an d oft e plunger 28 or 28 respectively and through a corresponding alteration in the diameter d, of section 17 of the differential piston-rod, every conceivable transmission ratio between the pressure of the operative medium for the thrust-piston motor means and the pressure of the substance being conveyed can be achieved. In this process the diameters d, and d, respectively and also d will always be increasingly approaching the diameter d as the transmission ratio increases, without however ever attaining the latter diameter.

I claim:

1. A pumping device comprising, in combination, a casing having first and second, spaced, opposed covers, an outer cylinder defined in said casing having an axis extending through said covers, a thrust piston movably mounted within said outer cylinder having an internal cylinder chamber defined therein, a fixed piston mounted upon said covers slidably received within said internal cylinder, said fixed piston including axially extending first and second portions of different diameter, a passage defined in said fixed piston extending through the associated covers, valve means defined on said piston communicating with said internal chamber and said passage whereby said piston and valve means function as a pump upon movement of said thrust piston relative to said fixed piston, supply passage means communicating with said chamber, and pressurized medium supply means communicating with said outer cylinder for reciprocating the thrust piston.

2. In a pumping device as in claim 1 wherein a pair of passages are defined in said fixed piston, and said valve means comprises first and second valves, each valve communicating with a passage.

3. In a pumping device as in claim 2 wherein said first valve communicates with said internal chamber adjacent said fixed pistons smallest diameter and said second valve communicates with said first valve.

4. In a pumping device as in claim 1 wherein the largest diameter of said fixed piston substantially corresponds to the diameter of said internal chamber.

5. In a pumping device as in claim 1 wherein said fixed piston includes a first portion of larger diametrical dimension than said second portion, a third portion defined on said fixed piston intermediate said first and second portions having a diameter greater than that of said first portion and sealingly engaging said inner chamber, said valve means including a first valve communicating with said chamber adjacent said first fixed piston portion anda second valve communicating with said chamber adjacent said second fixed piston portion.

6. In a pumping device as in claim 5 wherein said third fixed piston portion is homogeneously integral with said first portion.

7. In a pumping device as in claim 1, a pair of internal cylinder chambers defined in said thrust piston, a pair of fixed pistons mounted on said covers, each being received within one of said internal cylinder chambers, said pistons each having valve means, said valve means of said fixed piston being connected in series whereby movement of said thrust piston pumps medium through said fixed pistons in stages.

. a: a: :k

Claims

5. In a pumping device as in claim 1 wherein said fixed piston includes a first portion of larger diametrical dimension than said second portion, a third portion defined on said fixed piston intermediate said first and second portions having a diameter greater than that of said first portion and sealingly engaging said inner chamber, said valve means including a first valve communicating with said chamber adjacent said first fixed piston portion and a second valve communicating with said chamber adjacent said second fixed piston portion.