US 2038155 A
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Description (OCR text may contain errors)
April 21, 1936. B. G. ALDRIDGE I PUMP Filed sept. 11, 1934 .'v 'l ATTORNEY.
Patented Apr. 21, 1936 UNITED STATES PUMP Blair G. Aldridge, Los Angeles, Calif., assigner to Union Oil Company of California, Los Angeles, Calif., a corporation of California Application september 11, 1934, seria1N0.`743,564
lusually employed for the handling of highly viscous materials. This is due to the fact that such viscous substances stick and clog the port in and around the valve, thus preventing the efli- .cient handling of the material being pumped. Usually such valveless pumps consist of a cylinder having the suction inlet opening substantially into the middle portion of the cylinder, and discharge ports provided at the ends thereof, these discharge ports having valves which prevent the back-now of the iluid on the return. or suction stroke. A piston head, usually of a length substantially equal to or slightly greater than the internal diameter of the suction port, reciprocates Within said cylinder thus providing the motive power for the moving or pumping of the viscous liquid. This piston also acts as the valve for the suction port. Thus, when the piston is at the extreme right end of its movement the left portion of the cylinder is open to the inlet port andis thus filled with the liquid to be pumped. Then the movement of the piston to the left gradually closes the port until it is completely covered by the piston at Which time the uid thus trapped is moved into the discharge opening by the furthermovement of the piston. When the communication between the suction port and the cylinder is thus closed, and during the further movement of the piston to the left for the displacement of the uid from this portion of the cylinder, the right portion of the cylinder is then opened and is in communication with the suction port thereby permitting it to be filled With the liquid to be pumped, the subsequent movement of the piston to the right eventually closing said communication and causing the liquid trappedY in this portion vof the cylinder to be forced through its discharge port.
It is sometimes advantageous to use pumps of the above type, i. e. having no valve in the suction line, for the handling'and pumping of liquids having comparatively low viscosities. This is especially true Where the low viscosity liquid contains some substance in suspension. In such a case the elimination of the-valvein the inlet line is Aadvantageous because of the fact that in ordinary pumps such substance held in suspension will vhave a tendency to precipitate out on the valve thus clogging the port and preventing efficient pumping. Furthermore the elimination of (Cl. 10S-185) such inlet valve permits a surging or agitation of the liquid in the suction line, such surging being caused by the displacement oi a part of the fiuid fro-m the cylinder back into the said suction line during a portion of the movement of the piston. More specically stated, this surging action back into the inlet or suction line is created during the movement of the piston head across the inlet opening. One of the substances for which the above type of valveless pump may be used consists of a thin chilled slurry of lubricating oil and of a light liquefied hydro-carbon, such as liquid propane, containing Wax in suspension.
However, When the above type of pump is used for the handling of these lovv viscosity materials, and especially when there is a positive head on the suction line leading to the pump, the rapidity with which the cylinder is lled creates a severe hydrostatic hammer action, this hammering being caused by the rapid filling of the cylinder and the subsequent stopping of the flow oi the mixture into the pump cylinder when the latter is filled. This hammering condition is further aggravated' by the fact that during a part of the suction stroke, and more particularly during that portion of the stroke Which terminates with the opening of the cylinder to the inlet port, a partial Yvacuum is created back of the piston head. This vacuum tends to accelerate the filling of the pump cylinder, thereby increasing the severity and magnitude ofthe hammer action or shock when the cylinder is lining.
kIt is therefore an object of the present invention to provide a pump structure which eliminates all of the above enumerated and other defects. It is a further object of the invention to provide a pump structure of the type described hereinabove which may be employed for the handling of lovv viscosity liquids Without any detrimental hammering action.y
The above and other objects may be realized by providing a pump of the lalcove type With a piston having means which permit the gradual filling of the cylinder during the suction stroke. This eliminates any vacuum back of the piston as Well as the sudden iilling of the cylinder when it communicates with the inlet port. These means may consist of valves constructed and arranged so that as soon as the pump piston begins its suction stroke (as far as one end of the cylinder is concerned) this end of the cylinder is brought in communication With the inlet port through a valve or valves in the piston head, so that fluid Will be caused to flow into the cylinder gradually during said suction stroke, thus preventing the creation of any vacuum and/or the sudden inflow of fluid or liquid into the cylinder after the rear end (with respect to the direction of the movement) of the piston clears the inner wall of the inlet port and directly opens the communication between said port and the interior of the cylinder.
Therefore, broadly stated, the invention resides in an improved pump of the type having no valve in the inlet line, said pump having a piston provided with means which permit the inflow of liquid into the cylinder during the complete suction stroke. The invention further resides in a pump of the above described type having a piston provided with oppositely opening' valves disposed within the head of said piston. Y
More particularly stated, the invention resides in a pump for handling liquids, said pump comprising a cylinder, a valveless inlet port preferably opening into the central portion thereof, discharge ports leading from the ends of said cylinder, non-return or check valves in these discharge lines, and a piston' reciprocating in said cylinder, this piston being used for the opening and closing of the inlet port and being provided with valves which open outwardly with respect to the sides of the piston head and which communicate the inlet port with either end of the cylinder during the suction phase in such end.
Preferably, and for a proper functioning of the structure, the length of the piston head must be equal to or greater than the internal diameter of the inlet port. This piston head may be constructed as a single solid cylindrical structure having the above described valves, or it may preferably consist of two spaced circular heads of comparatively small thickness, these heads containing the valves for the elimination of the vacuum and of the resulting hammer action.
The invention will be more fully and clearly understood from the following description of preferred embodiments taken in connection with the accompanying drawing in which Figure 1 is a diagrammatic vertical section of `a preferred form of pump;
Figures 2 and 3 show diagrammatically and in simplified form the pump shown in Figure l, but with different positions of the piston in said pump to show the functioning of the valves there- 1n;
Figure 4 is a diagrammatic vertical section of a modified form of a piston which may also be used in connection with a pump cylinder having no valve in the inlet line; and
Figure 5 is a sectional View along line 5 5 of Figure 4. Y
Referring more particularly to the drawing, and especially to Figure l thereof, pump cylinder I0 is closed at its ends by plates II and I2, the
` latter being provided at its center with a stuffing box I3 for the passage therethrough of the piston rod I4. Substantially half way between the end plates II and I2, cylinder IIJ is provided with a line I6, said line being used as the suction or inlet line for the introduction into the pump cylinder I0 of the material to be pumped. It is to be noted that this line is not provided with any valve usually employed in connection with ordinary pumps to prevent the back-now of the liquid being handled. Cylinder I0 is provided adjacent the ends I I and I2 thereof with discharge lines I-'I and I1', respectively. The openings leading from the cylinderrto these lines are provided with seats I8 and I8'` adapted to receive f valves I9' and I9', respectively. These valves are held in closed position by means of springs 20 and 20 maintained in compression by spiders 2| and 2|', respectively. Obviously, when the pressure in the cylinder exceeds that of the discharge line, the valves are unseated to permit the fluid to be displaced into the respective discharge lines, while equalization of pressures causes the springs to force the valves against their seats, thus closing the communication between the pump cylinder and the discharge lines.
The actuation of the liquid is carried out by a piston head 23 positioned on the end of rod I4. In the preferred form shown in Figure 1 this piston head 23 consists of two circular elements 24 and 25 held on rod I4 in spaced relation to each other by means of hub or connecting element 26. The width of the elements 24 and 25 as well as the length of the connecting element 26 are such that the distance between the outer faces of said elements is equal to and preferably slightly greater than the internal diameter of the inlet line or port I6. The reason for such an arrangement will be obvious from the explanations of the operation of the structure to be given hereinbelow. The circular elements 24 and 25 abut against the inner walls of the cylinder I0 and are provided in the usual manner with rings 21, the purpose of which is obvious to those skilled in the art. Each of the circular elements 24 and 25 is also provided with one or more ports 29 which are normally held in closed position by valves 30 actuated by springs 3|.- These valves are arranged and constructed'so that they open towards the end of the cylinder which they face, i. e. valves 3U in the cylindrical element 24 open towards the left as shown in the drawing, while the valves in element open to the right. The stroke of the piston de` scribed hereinabove is such that the piston head 23 completely clears the inlet line or port I6. Therefore, in Figure 1, the position of the vpiston head 23 shows the limit of the travel of the piston to the right, while its limit of travel in the opposite direction is shown by the dotted lines on the same figure.
In operation, and assuming that the piston has reached the limit of its travel to the right, asv shown in Figure l, and begins to move in the opposite direction, the enlargement of the chamber in the cylinder I0 between the end I2 and the piston head will tend to cause a partial vacuum to be generated therein. This in turn will cause the opening of the valves in the circular element 25 thus equalizing the pressure to the right of the element 25 with the space between the elements 24 and 25. A further movement of the piston head 23 to the left will cause the element 24 to clear the opening or port I6 thus permitting the liquid from said suction line I6 to enter into the space between the elements 24 and 25, and then through the open ports in element 25 into the space to the right of the piston head. It is thus seen that at this stage of operations both discharge valves I9 and I9 are closed, the valves in the cylindrical element 24 are closed while those in 25 are open. This phaseis shown in Figure 2 and continues until the outer face of the cylin? drical element 25 clears inlet line I6 as shown in Figure 3. When this occurs, the liquid to'be pumped iiows directly from the suction line I 6,
into the' cylinder I0 to the right of the piston headV 23, there being no substantial rush of liquid into said cylinder since the liquid has been continuously flowing thereinto during the travel of the' piston. When direct flow of liquid' into the cylinder I 0 is thus established, there is no differential in pressure on the two sides of the cylindrical element 25, and the valves in said element close. Since the distance between the outer surfaces of the circular elements 24 and 25 is equal to slightly greater than the inner diameter of the suction or inlet line I6, as soon as element 25 clears inlet I6, element 24 closes the communication between said line I6 and the space inthe cylinder IIJ to the left of the piston. Thereafter, any further movement of the piston, to the left compresses the liquid trapped in the cylinder I0 between the end Il and the piston 23. 'I'his compression of the liquid forces the upward displacement of Valve I9 in discharge line il and the passage of the liquid from the piston into said discharge line. When the piston has reached its extreme left limit of travel (as shown in dotted lines in Figure 1), it begins to move to the right. This tends to create a partial vacuum in the space to the left of the piston, thus closing valve I9 and opening valve 30 in the piston element 24. The opening of this valve 30 permits the fluid to pass through the ports in the element 24 into the space to the left thereof thus preventing the creation of any .vacuum and the sudden rush of liquid when direct communication is again established between the suction line I6 and the portion of the cylinder l! to the left of the piston.
It is thus obvious that the provision of the above described type of piston and of the valves in said piston eliminates the defects caused by any generation of Vacuum on the suction stroke of the piston. This elimination of vacuum prevents the above described suction inflow of liquid, especially if such liquid is of a low viscosity, thus avoiding any detrimental hammer action.
Instead of providing a piston head shown in Figures 1, 2, and 3, it is possible to use a solid piston head shown in Figure 4, such head being of a thickness or length equal to or slightly greater than the internal diameter of the inlet port I6. This head is provided with oppositely disposed valves 36 and 31 which close ports 38 and 39, respectively, these ports being bored at an angle in the cylinder and leading to the circumferential side thereof substantially near the end of the piston head opposite to that on which the respective valves are located. The operations of this type of a piston head are the same as when using the piston head 23 of Figures 1-3. Thus, when the piston head is moved to the left, the space to the right of the piston head is in communication with the inlet port I6 through port 39, while when the piston is moving in the other direction valve 36 is unseated, thus communicating the space to the left of the piston head with the line I6 through port 38.
1. A pump for handling liquids, comprising a cylinder, a valveless inlet port opening into an intermediate portion thereof, valved discharge ports adjacent the ends of said cylinder, and a piston of a length substantially equal to the diameter of inlet port, adapted to be reciprocated in said cylinder and provided with passages adapted to communicate with the inlet port and equipped with oppositely opening valves.
2. In a structure according to claim 1, wherein the last-mentioned valves open outwardly with respect to the ends of the piston.
3. A pump for handling liquids, comprising a cylinder, a valveless inlet port opening into an intermediate portion thereof, discharge ports adjacent the ends of said cylinder, check-valves in said discharge ports adapted to prevent back-now of liquids, and a piston adapted to be reciprocated in said cylinder, comprising two spaced heads provided with valved passages adapted to communicate with the inlet port and being provided with valves, said heads being spaced substantially the diameter of the inlet port.
4. In a structure according to claim 3, wherein the last-mentioned valves open in directions opposite to each other'.
5. In a structure according to claim 3, wherein the last-mentioned valves in the two heads open outwardly with respect to the piston assembly.
BLAIR G. ALDRIDGE.