US3289597A

US3289597A - Centrifugal pump

Info

Publication number: US3289597A
Application number: US332441A
Authority: US
Inventors: Stehrenberger Max; Rasmussen Leif
Original assignee: K RUTSCHI AG
Current assignee: K RUTSCHI AG
Priority date: 1963-01-16
Filing date: 1963-12-23
Publication date: 1966-12-06
Anticipated expiration: 1983-12-06
Also published as: AT247158B; CH396640A; DE1528800A1; GB1062178A

Description

HEAD OF ELEMT/O/V Dec. 6, 1966 M. STEHRENBERGER ETAL 3,239,597

CENTRIFUGAL PUMP Filed Dec. 25, 1963 2 Sheets-Sheet 2 HEAD OF ELEVATION A PUMP our/ ar Q 30% aur ur Q 1007,

FIG.3 FIGS BY wjamg W United States Pater 3,289,597 CENTRIFUGAL PUMP Max Stehreuberger, Brugg, Switzerland, and Leif Rasmussen, Glostrup, Denmark, assignors to K. Rutschi AG, Pumpenbau Brugg, Brugg, Switzerland Filed Dec. 23, 1963, Ser. No. 332,441 Claims priority, application/ivgitzerland, Jan. 16, 1963, 4 Claims. (Cl. 103-97) Actually the demand for centrifugal pumps, particularly in the central heating field where such pumps are used as circulators is such that the plumbers and the wholesalers keep stocks of them. Unfortunately, since the various types of central heating installations also require pumps of varying output, these dealers are obliged to have on stock several different types of pumps in order to be in a position to meet the demand.

Of course the number of different types of pumps may be limited by constructing the pumps for an output that covers the largest possible range of application. Smaller intermediate outputs may also be obtained by cutting down on a lathe the pump impeller to a smaller diameter. However this last-mentioned step may be effected in a workshop only. Now it may well occur that the pump output should be modified after the mounting of the pump into the central heating installation, for example if it appears then only, that the pump output is too large or too small. The removal of the pump and its subsequent building-in in such a case is time-wasting and complicated so that it has been looked for a solution permitting adjustment of the pump output with the pump remaining mounted in the installation.

An adaption of a circulating pump to an existing central heating installation would be possible by using gate valves, arranged immediately before and after the pump, to effect a throttling acting. But generally there is no possibility to fixedly adjust the conventional gate valves in a desired position. Thus each time such a gate valve has to be closed entirely in accordance with the prime object of such valves, be it for a checking of the central heating installation or because the installation is set out of operation, the subsequent readjustment to the correct opening corresponding to the desired pump output is rendered difiicult. Also in the case of such a' throttling by means of gate valves it is never exactly known which is the actual pump output that is thereby obtained.

For all these reasons many attempts have been made to obtain different output curves by means of simple devices provided at the pump itself, in order to afford for subsequent regulation of the pump output when the pump is built-in on the one hand but also, on the other hand, in order to make possible for the dealers to satisfy various requirements for output with the least possible number of different pump types.

For example it is known that the output measured at the pressure side of the pump may be influenced by a lateral displacement of the impeller leading to a partial backflow of the accelerated fluid, or by the provision of a bypass through which the fluid is guided back from the pressure side to the suction side. This type of power regulation has the important drawback that the highest power consumption appears for the smallest pump outputs so that pumps adjusted in this manner are very uneconomical in operation.

The prime object of the present invention is to realize a circulating pump with an incorporated power regulation, which does not present any of the afore-mentioned drawbacks.

A further object of the invention is the realization of ice a power regulation that leads to small power consumption when adjusted for small pump output and to larger power consumption only when adjusted for higher pump output.

These and other objects are obtained according to the present invention by the provision of a throttling member mounted into the pump casing and adapted to regulate the amount of fluid flowing through the pump.

This throttling member may be mounted into the suction side of the pump, whereby the best constructional, mechanical and esthetical results are obtained.

However, if for any reasons, there is danger of formation of cavitations the throttling member may as well be built-in at the pressure side of the pump.

In both cases it is still a further object of the invention to realize a stepless regulation of the pump output by the provision of a steplessly adjustable throttling member.

A still further object of the invention is to facilitate the adjustment of the desired pump power by means of the throttling member in such manner that the amount of fluid allowed to pass through the pump is varied proportionally with the angle about which the throttling member is rotated. This aim is achieved according to the invention by a corresponding form given to the gate wall of the throttling member that projects into the fluid current.

Other features and advantages of the invention will become apparent from the description now to follow, of preferred embodiments thereof, given by way of example only, and in which reference will be made to the partly diagrammatical accompanying drawings, in which:

FIGURE 1 is a section through a circulating pump having a throttling member incorporated into its suction side;

FIGURE 2 is a view of the outer parts serving to the adjustment of the pump output of the throttling member of FIGURE 1 as seen from left to right in the latter figure.

FIGURE 3 is a representation of output curves of the pump of FIGURE 1 for different adjusting positions of the throttling member.

FIGURE 4 illustrates, diagrammatically, a known output regulation for a circulating pump by means of a bypass, and

FIGURE 5 illustrates output curves of the known arrangement of FIGURE 4 for different adjustments.

Referring now to the drawings, in FIGURE 1 reference numeral 1 designates a rotary throttling gate arranged in the suction opening 3 of the casing 4 of a centrifugal pump directly opposite the pump impeller 5. The outline of the gate wall 2 is selected in such manner that when a gate button 6, accessible from the outside of the pump, is turned, that then the fluid amount allowed to pass through the pump, i.e. the pump delivery, increases proportionally to the angle of rotation. For example in the fully open position of the throttling member (position IV in FIGURE 2) the maximum amount of fluid shall be delivered, and in the half-closed position of the throttling member (position II in FIGURE 2) accordingly half of the maximum amount shall be allowed to pass through the pump. .Moreover the gate wall 2 may have such an outline as to completely close the suction tube 3 when the throttling member is closed (position 0 in FIGURE 2) or that when this position is adjusted by means of the gate adjusting button 6, still a minimum amount of fluid is allowed to flow through the pump for security reasons. The last-mentioned eifect may of course also be obtained by means other than a particular outline shape of the gate wall.

At the passage of gate 1 through the pump casing 4 a sealing ring 7 prevents leakage. According to FIGURE 2 the gate button 6 is provided with a hand cooper- I ating with a scale on the pump casing indicatingthe positions of the button 6 when the pump output is regulated between ,1 and of the maximum output. A pair of lateral abutments 9 prevent turning of the button 6 beyond its regulating range.

Instead of being mounted centrally in the suction opening 3 as shown and described hereinbefore the throttling member may also be mounted into the pressure side tube of the pump designated by reference numeral 10. Such an arrangement is indicated in dot-and-dash lines in FIGURE 1. It is to be understood that the described output regulation is not limited for use in connection with central heating circulators but may be incorporated analoguously into any other centrifugal pump. Nevertheless it is with central heating circulators that its widest possibilities of use and largest advantages appear.

FIGURE 3 illustrates the output regulation that may be obtained with the above described arrangement of a throttling member. With the gate button 6 in position IV the passage to the impeller in the suction opening 3 is completely free resulting in the maximum output shown by the output curve IV. In the positions III, II and I of the rotary gate button 6 the throttling member is adjusted to throttle down more and more the passage for the fluid, resulting in correspondingly reduced output curves. Thereby the power consumption of the pump is highest when the pump is regulated to full output and decreases with decreasing pump delivery in accordance with the normal behavior of a radial centrifugal pump impeller. Thus with the described means for regulating the pump output an economical ratio is obtained for all operation points, between the output and the power consumption.

In order to make appear the progress of this output regulation over the already known solutions, one of the latter, namely the known output regulation by means of backflow through a bypass conduit shall hereafter be compared with the output regulation according to the invention.

FIGURE 4 diagrammatically shows a pump 12 in which the backflow, which generally takes place within the pump through a boring from the pressure side into the suction side of the pump, is shown to flow through a separate backflow bypass 13 for the sake of clarity.

Assuming now that a central heating installation is provided with a stock pump having a maximum output of 100% of which, say, only 30% are actually required. The backflow valve 14, connected into the bypass 13 may then be opened to such an extent, that 70% of the de livered fluid flows back from the pressure side to the suction side.

FIGURE illustrates the output curves obtained with such an output regulation by means of backflow. With the bypass valve 14 closed, i.e. with no back flow at all, the obtained output curve IV corresponds to the curve IV of FIGURE 3. As soon, however, as the valve 14 is opened and a certain amount of backflow established the obtained curves III, II and I difler from the curves of FIGURE 3 corresponding to the same pump output. If, for a determined conduit resistance of a central heating installation or owing to a small required head of elevation H only, say, 30% of the maximum pump output are required the power consumption will be, as clearly shown, the same as for the full output of 100% of the pump. With this output regulation by backflow the contradictory aspect occurs, that for the maximum output of the pump thepower consumption curve is the lowest while for the smallest output, according to the output curve I, the power consumption is the highest.

This clearly demonstrates the technical progress obtained with the output regulation according to the present inventiOH, whereby, in addition, the obtained output curves as represented in FIGURE 3 have particular advantages in connection with the operation of circulators for central heating installations. With the arrangement according to the invention it is possible to determine very easily the required output of a circulating pump, since the required heating output in ratio to the desired temperature difference indicates the necessary output. The head of elevation of a pump is substantially more diflicult to calculate'since the conduits lengths and the number and type of castings strongly influence the calculation.

With the output regulation according tothe present invention a precise prior calculation of the conduit re sistance and of the head of elevation is of minor importance since the fluid output, which is important for the temperature difference remains'practically the same over a wide range independently of the head of elevation.

We claim:

1. A circulating pump comprising a pumpcasing defining an impeller chamber, a transverse inlet passage leading to said impeller chamber and including an inlet chamber adjacent to and coaxial with said impeller chamber and a discharge passage leading away from said impeller chamber, an impeller rotatably mounted in said impeller chamber, means connected to said impeller to rotate said impeller, a throttle member mounted in said inlet chamber and being rotatable to vary the flow area through said inlet passage, said throttle member comprising a gate including a wall portion which may be moved across the inlet passage to block at least a portion of the flow therethrough, and adjusting means on the exterior of said casing connected to said throttle member to rotate said throttle member to vary the amount of fluid circulated through said inlet passage to said impeller.

2. A circulating pump comprising a pump casing defining an impeller chamber, a transverse inlet passage leading to said impeller chamber and including an inlet chamber adjacent to and coaxial with said impeller chamber and a discharge passage leading away from said impeller chamber, an impeller rotatably mounted in said impeller chamber, a throttle member mounted in said inlet chamber and being rotatable to vary the flow area through said inlet passage, said throttle member comprising a gate including a wall portion which may be moved across the inlet passage to block at least a portion of the flow therethrough, adjusting means on the exterior of said casing connected to said throttle member to rotate said throttle member to vary the amount of fluid flow through said inlet passage to said impeller, and a motor connected to said impeller to rotate said impeller arranged on the side of said impeller opposite to said throttle member.

3. A circulating pump comprising a pump casing defining an impeller chamber, a transverse inlet passage leading to said impeller chamber and including an inlet chamber adjacent to and coaxial with said impeller chamber and a discharge passage leading away from said impeller chamber, an impeller rotatably mounted in said impeller chamber, means connected to said impeller to rotate said impeller, a throttle member mounted in said inlet chamber and being rotatable to vary the flow area through said inlet passage, said throttle member comprising a gate including a wall portion which may be moved across the inlet passage to block at least a portion of the flow therethrough, and a rotatable member mounted on the exterior of said casing and connected to said throttle member to rotate said throttle member in proportion to the rotation of said rotatable member to vary the flow area through said inlet passage.

4. A circulating pump comprising a pump casing defining an impeller chamber, a transverse inlet passage leading to said impeller chamber and including an inlet chamber adjacent to and coaxial with said impeller chamber and a discharge passage leading away from said impeller chamber, an impeller rotatably mounted in said impeller chamber, means connected to said impeller to rotate said impeller, a throttle member mounted in said inlet chamber and being rotatable to vary the flow area through said inlet passage, said throttle member comprising a gate including a Wall portion which may be moved across the inlet passage to block at least a portion of the flow therethrough, and a rotatable member mounted on the exterior of said casing and connected to said throttle member to rotate said throttle member in proportion to the rotation of said rotatable member to vary the flow area through said inlet passage, said rotary member comprising a knob having an index point, and scale means defined on said casing adjacent said knob for indicating the adjustment of said throttle member.

References Cited by the Examiner UNITED STATES PATENTS 5/1909 Trent 103-97 3/1917 Doble 10397 8/1923 Sherzer 103-97 12/1943 Gregory 230--114 7/1964 Tyler 103--97 FOREIGN PATENTS 1/ 1909 Great Britain. 10/1913 Great Britain.

9/ 1940 Sweden.

15 LAURENCE V. EFNER, Primary Examiner.

Claims

1. A CIRCULATING PUMP COMPRISING A PUMP CASING DEFINING AN IMPELLER CHAMBER, A TRANSVERSE INLET PASSAGE LEADING TO SAID IMPELLER CHAMBER AND INCLUDING AN INLET CHAMBER ADJACENT TO AND COAXIAL WITH SAID IMPELLER CHAMBER AND A DISCHARGE PASSAGE LEADING AWAY FROM SAID IMPELLER CHAMBER, AN IMPELLER ROTATABLY MOUNTED IN SAID IMPELLER CHAMBER, MEANS CONNECTED TO SAID IMPELLER TO ROTATE SAID IMPELLER, A THROTTLE MEMBER MOUNTED IN SAID INLET CHAMBER AND BEING ROTATABLE TO VARY THE FLOW AREA THROUGH SAID INLET PASSAGE, SAID THROTTLE MEMBER COMPRISING A GATE INCLUDING A WALL PORTION WHICH MAY BE MOVED ACROSS THE INLET PASSAGE TO BLOCK AT LEAST A PORTION OF THE FLOW THERETHROUGH, AND ADJUSTING MEANS ON THE EXTERIOR OF SAID CASING CONNECTED TO SAID THROTTLE MEMBER TO ROTATE SAID THROTTLE MEMBER TO VARY THE AMOUNT OF FLUID CIRCULATED THROUGH SAID INLET PASSAGE TO SAID IMPELLER.