US2688846A

US2688846A - Pump and motor hydraulic system

Info

Publication number: US2688846A
Application number: US247321A
Authority: US
Inventors: Ruden Raymond E Von
Original assignee: Individual
Current assignee: Individual
Priority date: 1951-09-19
Filing date: 1951-09-19
Publication date: 1954-09-14
Anticipated expiration: 1971-09-14

Description

P 14, 1954 R. E. VON RUDEN PUMP AND MOTOR HYDRAULIC SYSTEM 2 Sheets-Sheet 1 Filed Sept. 19, 1951 p 14, 1954 R. E. VON RUDEN 2,688,846

PUMP AND MOTOR HYDRAULIC SYSTEM Filed Sept. 19, 1951 2 Sheets-Sheet 2 I I I I I IN V EN TOR.

@WMJ. 7622M BY WM ,47 7 ORA/f VJ Patented Sept. 14, 1954 UNITEDSTATES PATENT OFFICE 2 Claims.

My invention relates generally to fluid pressure apparatus and more specifically to fluid pressure systems and pump structure therefor.

More particularly, my invention relates to improvements in a so-called open fluid pressure system, that is, the type of system which includes a fluid supply tank or reservoir open to atmosphere and from which a pump receives fluid for delivery to a fluid pressure motor or the like under relatively high pressure, from whence said fluid is returned to the reservoir under relatively low pressure. The instant invention utilizes the advantages of both open and closed types of fluid pressure systems to obtain maximum efficiency with a minimum of loss due to friction or heat.

An important object of my invention is the provision of means, in a fluid pressure system having driving and driven elements, whereby a portion of the fluid discharged from the driven element is returned directly to the driving element for recirculation therethrough.

Another object of my invention is the provision of novel means for introducing fluid to a pump in a fluid pressure system.

Another object of my invention is the provision of a pump having inlet and discharge passages each communicating with an impeller chamber, one end portion of said inlet passage being angularly disposed with respect to the other end portion thereof, and means for introducing fluid to the inner end of said inlet passage in a direction axially thereto, whereby Venturi action is obtained. 7

Still another object of my invention is the provision of a pump for a fluid pressure system of the above type which is relatively simple and inexpensive to produce, which is eflicient in operation, and which is rugged in construction and durable in use.

Other highly important objects and advantages of my invention will become apparent from the following detailed specification, appended claims, and attached drawings.

Referring to the drawings which illustrate the invention and in which like characters indicate like parts throughout the several views:

Fig. 1 is a view partly in side elevation and partly diagrammatic of a fluid pressure system built in accordance with my invention and incorporating my novel pump;

Fig. 2 is a top plan view of the pump of my invention on an enlarged scale; and

Fig. 3 is a vertical section taken on the line 3-3 of Fig. 2.

In the preferred embodiment of my invention reservoir l, a pump 2, a fluid pressure operated motor 3 and conduit means hereinafter described. The fluid pressure motor 3 is conventional in nature and may be of any one of a number of types commonly used as driven elements in a fluid pressure system. For the purpose of the present example, it may be assumed that the motor 3 comprises a pair of intermeshing spur gears, not shown but mounted one each on one of a pair of shafts 4 and 5 journalled in the motor casing identified by the numeral 6. A conduit is connected to the inlet 8 of the motor 3, the discharge 9 of the motor being coupled to a conduit, indicated by a broken line I8, by means of a suitable fitting such as an elbow II. Either of the shafts 4 or 5 may be extended laterally outwardly of the motor casing 6 to provide power take-01f means.

The pump 2 includes a casing having a main body l2 and a pair of opposed cover elements or plates l3 and I4 one each rigidly secured to an opposite side of the main body I2 by means of machine screws or the like l5. Said body and cover plates define a chamber l6 which contains a pair of intermeshing spur gears l1 and 18 that are keyed or otherwise anchored to laterally spaced parallel shafts l9 and 20 respectively journalled in spaced bearing bosses 2| integrally formed with respective cover plates l3 and 14. One of the shafts, as shown the shaft I9, extends laterally outwardly of the cover plate [4 and is adapted to be coupled to a source of rotary power to operate the pump 2.

The pump 2 is provided with inlet and

outlet passages

22 and 23 respectively each communieating with the chamber IS. The inlet passage 22 at its inner end 24 adjacent the chamber i6 is angularly disposed with respect to its outer end portion 25. As indicated in Fig. 1, the conduit l is connected to the discharge passage 23 by suitable means such as a pipe fitting in the nature of an elbow 26, and a conduit 2! extends from the supply tank or reservoir I to the outer end 25 of the inlet passage 22. As also indicated in Fig. 1, a portion of the conduit 21 is indicated by broken lines.

The main body -l2 of the pump 2 is formed to provide a duct 28 which extends therethrough in spaced relation to the inlet passage 22, said duct having an inlet port 29 and an outlet port 30. The conduit I0 extendingfrom the discharge of the fluid motor 3 is connected to the inlet port 29 by means of a pipe fitting in the nature of an elbow 3| whereas the outlet end or port 30 of the duct 28 has screw-threaded therein a return conduit 32 which extends to the reservoir I, as indicated by broken lines in Fig. 1.

The above-described apparatus provides a fluid pressure system of the so-called open type wherein all of the fluid pumped to and through the motor 3 by the pump 2 is returned to the reservoir I. The open type system is advantageous, in one respect, in that the fluid returned to the reservoir has a chance to lose some of the heat of friction resulting from its circulation through the pump and motor and the connecting conduits therefor before it is recirculated. However, this type of system is at a distinct disad vantage over the closed system wherein fluid discharged from the motor is returned directly to the inlet of the pump, in that an appreciable amount of power is consumed by the pump in drawing fluid from the supply tank or reservoir, particularly when the reservoir is located at some distance from the pump and at a level therebelow. Ina normal closed system, difficulty is often experienced in maintaining a relatively cool temperature of the fluid and in preventing the same from foaming or becoming excessively aerated. To utilize the advantages of both systerns, and to avoid the disadvantages thereof, I provide shunt means in the nature of a shunt or branch passage 33 extending from the duct 28 to the inlet passage 22 within the main body l2 of the pump. With particular reference to Fig. 3, it will be seen that the shunt passage 33 is axially aligned with th inner end portion 2d of the inlet passage 22. It will also be noted that the shunt passage 33 is of smaller cross-section than is the passage 22. In practice, the passage 33 has a cross-sectional area which is less than one-half the cross-sectional area of the passage 22.

In operation, rotary movement imparted to the intermeshing spur gears IT and iii, in directions indicated by the arrows thereon in Fig. 3, will cause fluid to be drawn into the chamber $6 from the reservoir 1 through the inlet 22 and forced outwardly of the discharge passage 23 to and through the motor 3 to impart rotary movement to the shafts 4 and 5 thereof. Fluid discharged from the motor 3 is returned to the duct 28 under pressure through the conduit iii, a portion of said fluid entering the inlet passage 22 through the shunt passage 33. The passage 33 being of insuflicient size to carry the entire amount of fluid under pressure delivered to the inlet of the duct 28 from the motor 3 the remainder of the fluid in the duct '28 returns to the reservoir I through the conduit 32. Since a pressure is required to return the fluid from the motor 3 to the reservoir I a pressure is built up in the duct 28. The fluid entering the passage 22 is under relatively'low pressure and is drawn toward the chamber l6 through the shunt passage 33 which is directed across the passage 22 toward the pump gears ll, H3 at the inlet side of chamber l6 forming a jet action across the passage 22 and creating a Venturi action therein. Such active supplements the negative pressure in the inlet passage 22 created by the suction of the pump gears l'I-IB, thus reducing the possibility of cavitation at the pump inlet and materially increasing the efiiciency of the pump by assisting in keeping the inlet passage 24 completely filled with liquid. Part of the fluid in the conduit It] returns to the reservoir I, the remainder thereof being recirculated through the pump 2 and the motor 3. The fluid moving through the shunt passage 33 is cooled by the fluid entering the inlet passage 22 from the conduit 21 while at the same time increasing the efficiency of the pump by overcoming to an appreciable extent the power loss suifered by the pump in drawing fluid from the supply tank I. Moreover, when the pump has been idle for a period of time, sufficient fluid remains in the duct 28 as well as in the inlet passage 22 to obviate the necessity of priming the pump 2 when it is again desired to operate the same.

In practice, I have found that greatly increased efiiciency has been obtained in driving fluid pressure operated motors with my invention in the manner above described. In fact, by use of my novel arrangement, I have been able to triple the speed of the motor without increasing the speed of the pump, and heating of the fluid du to friction in the various component elements of the system has been kept to a minimum.

While I have shown and described a preferred embodiment of my novel fluid pressure system and pump therefor, it will be understood that the same is capable of modification and that modification may be made without departure from the spirit and scope of the invention, as defined in the claims.

What I claim is:

l. A fluid pressure system comprising a pump having a housing defining a chamber having impeller means therein and inlet and outlet passages communicating with said chamber, a fluid pressure operated motor having an inlet and an outlet, a fluid conduit connecting the outlet pa sage of said pump to the inlet of said motor, a fluid reservoir, a conduit delivering fluid from said reservoir to the inlet passage of said pump, said housing further defining a duct having an inlet and an outlet, a conduit connecting the outlet of said motor to the inlet of said duct, conduit means connecting the outlet of said duct to the reservoir, said inlet passage to the pump chamber having a restricted portion and an expanded portion, said expanded portion being adjacent the pump chamber and angularly disposed with re" spect to said restricted portion, said housing further defining a shunt passage communicating with said duct and the expanded portion of said inlet passage, said shunt passage being in alignment with said expanded portion, the total cross sectional area of said shunt passage being of insufiicient size to carry the full amount of the fluid delivered to the intake of said duct thus creating a positive pressure in the duct, the fluid under the positive pressure-entering the expanded portion of said inlet passage through said duct and shunt passage and across said inlet at a predetermined speed of the pumping movement of said impeller means and cooperating with said impeller means to create relatively high negative pressure in the restricted portion of said inlet passage.

2. The structure defined in claim 1, wherein the shunt passage has a smaller cross sectional area than said inlet passage.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 985,986 Eisermann Mar. 7, 1911 2,056,994 Woods Oct. 13, 1936 2,343,486 Stepanoff Mar. '7, i944 FOREIGN PATENTS Number Country Date 361,823 Germany Oct. 19, 1922 234,209 Great Britain May 28, 1925