US 3529421 A
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Description (OCR text may contain errors)
Sept. 22, 1970 K. G. NEELEY 3,529,421
JET-PUMP OIL-RETURN SYSTEM 7 Filed Nov. 18, 1968 Z/RESERVOIR V 9 5 I I!!! 7 I 41H 7 I 6- I l0 3 III/I "'ENTOR. KE/ TH ELEY United States Patent 3,529,421 JET-PUMP OIL-RETURN SYSTEM Keith G. Neeley, Highland Park, Calif., assignor to K. M. White Company, Louisville, Ky., a corporation of Kentucky Filed Nov. 18, 1968, Ser. No. 776,429 Int. Cl. F15b 15/18, 21/04; F04f /02 US. Cl. 60-52 7 Claims ABSTRACT OF THE DISCLOSURE The invention is of an automatic oil scavenging unit for hydraulic elevator systems powered by a jet pump. Oil leaking from around the elevator actuating jack is collected and fed to the low-pressure input side of a jet pump. The jet pump is driven by high-pressure liquid taken from the output side of the main elevator actuating pump. The output of the jet pump is delivered to the hydraulic storage tank for the system.
BACKGROUND The invention is in the field of hydraulic elevator actuating systems and pertains specifically to a means for collecting oil which leaks from the main actuating piston in such systems, and returning it to the hydraulic storage tank.
An important problem associated with systems of this type has been the necessity for a separate source of power to drive whatever means was utilized to collect and transfer oil leaking from the associated hydraulic system. In addition, there have been associated problems of capacity, location, Wear and tear, and expense inherent in such systems.
The system and pump device of the invention provide a fully automatic oil-return system requiring a minimum of space, and providing a great flexibility as to its location with respect to the hydraulic elevator system.
It is an objective of this invention to provide an oilreturn system of the character indicated which operates automatically at all times when the main hydraulic pump is in operation.
It is a further objective of this invention to provide an automatic oil-return system With substantially no moving parts.
It is a further objective of this invention to provide an automatic oil-return system which is hydraulically operated.
It is still another objective of this invention to provide an automatic oil-return system which requires no independent mechanical power source for its operation, and which does not noticeably affect the capacity of the main elevator-pump system to operate the elevator.
SUMMARY Basically, the system of the invention is comprised of a jet pump with a high-pressure inlet side attached to the output of the main hydraulic pump which drives the elevator jack, a low-pressure input side connected to a collecting collar mounted upon the main hydraulic jack and around the actuating piston, and an output which connects to the hydraulic storage tank for the elevator system.
The jet pump of the invention is comprised of an inlet jet tube and an exhaust tube mounted along a common axis within the cross bar of a hollow T-shaped tubular housing. The hollow stem of the T-shaped housing comprises the low-pressure inlet for the pump. A ball-type check valve disposed within said low-pressure inlet prevents oil from flowing back through the discharge line to the collecting collar.
3,529,421 Patented Sept. 22, 1970 The invention has the advantage of providing a high capacity automatic oil return system at a minimum of cost.
The system has the additional advantage of requiring a minimum of space, as the pump is very small and requires only three small lines to incorporate it within the elevator system.
In addition the system has been found capable of lifting return oil to the extent of at least 26 feet at sea level, thus providing considerable latitude in its positioning with respect to the remainder of the hydraulic system.
Other objectives, advantages, and various further features of novelty and invention will be pointed out or will occur to those skilled in the art from a reading of the following specification in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic layout of a simplified hydraulic elevator system incorporating the invention; and
FIG. 2 is a cross-sectional view of the jet pump of the invention and forming part of the layout of FIG. 1.
DETAILED DESCRIPTION Referring now to FIG. 1, a simplified hydraulic elevator system is depicted. A main hydraulic pump 1 delivers liquid from a reservoir 2 through a control valve 3 to a main actuating jack 4. When pump 1 is in operation, hydraulic fluid under high pressure is delivered to jack 4, causing actuating piston 5 to move out of cylinder 6 and raising the elevator car (not shown). As some hydraulic fluid will inevitably leak from the actuating cylinder around piston 5, a collecting collar or manifold 7 is mounted to cylinder 6 at the point of exit of actuating piston 5.
Oil collected by collar 7 is drawn off by jet pump 8 and delivered to reservoir 2. As the oil leaves collar 7 it is passed to a scavenge pump 8 by way of a filter 9, as shown incorparated in a branch-Y body, for clean-out and maintenance convenience.
In accordance With the invention the scavenge pump 8 is self-operating from high-pressure hydraulic fluid bled from the output side 10 of the hydraulic pump 1, so that whenever pump 1 is in operation, pump 8 will be Operative to scavenge oil which has collected in collar 7. Valve 3 is a control valve which delivers hydraulic fluid under high pressure to jack 4 to move the elevator up, and permits fluid to escape from cylinder 6 to move the elevator down, and the flow which is bled from the pump-output line 10 is so insubstantial as to result in no noticeable impairment of elevator-jack operation, even for existing elevator installations.
Referring now to FIG. 2, the scavenge pump is seen to comprise a simple jet pump including a tubular substantially T-shaped body 12 having a cross bar member 13 with a stem 14 extending therefrom.
The high-pressure inlet end 15 of pump 8 has a pipe fitting or nipple 16 inserted therein, to facilitate attachment of the high-pressure hydraulic feed line and to sup port an internal part 17 of the jet pump. Part 17 is an orifice member or bushing having a restricted bore 18 and is adjustably threaded to the inner end of bore 19 of the fitting 16. The outer end 20 of bore 18 has a counterbore of polygonal cross section designed to permit axial adjustment of member 17 within fitting 16, as by means of an Allen-type wrench.
A short length of tubing 21, which may be brass tubing, is carried by member 17 and forms the high-pressure inlet for the jet pump. The outer end 21a of tube 21 may be soldered within the bore 18, care being taken that the longitudinal axis thereof is aligned with a. bore 22 in cross bar 13 of the pump body.
The output end 24 of the jet pump carries an end-connection fitting or nipple 25 similar to fitting 16, and a length of tubing 26, larger in diameter than tube 21, is secured, as by solder, in the counterbored end of a bushing 28 having threaded engagement in the bore of fitting 25; the counterbore 27 is adjacent an Allen-type socket formed in the remainder of the bushing bore, for axialadjustment purposes. Care must be taken in mounting tubes 21 and 26 to assure that their longitudinal axes are aligned, such that tube 21 points directly down the center of tube 26.
The low-pressure inlet 30 of. pump 8 is at the Open end of stem leg 14 of the T-shaped body 12. Threaded into inlet 30 is a ball-check valve 31 which permits oil to flow only in the direction of pump 8.
In operation, high-pressure liquid from pump enters the high-pressure inlet of pump 8, where it is forced through tube 21, creating a small high-speed jet of hydraulic fluid which is directed down the center of tube 26. This high-pressure jet causes substantially all of the molecules of matter Within tube 26 to move through outlet 24, which induces a partial-vacuum condition within chamber 32, being the remaining or otherwise unoccupied internal volume of the jet-pump body 12. With the vacuum thus created, atmospheric pressure will cause oil collected within collar 7 to flow through filler 9 and into chamber 32. Oil in chamber 32 is then picked up by the jet emerging from tube 21 and forced in the direction of reservoir 2.
The spacing between the inner ends 21b of tube 21 and 26a of tube 26 is critical, but may be readily set by Allen-type adjustment. For best results the hydraulic jet emerging from tube 21 should be aimed precisely down the center of tube 26. If the spacing between tubes 21 and 26a of tube 26 is critical, but may be readily set by pump is greatly reduced. A spacing of -in. to A -in. is recommended for a pump having tubing of the following dimensions: inlet high pressure tube 21, -in. (O.D.) standard brass tubing, and outlet tube 26, t in. (O.D.) standard copper tubing. A pump constructed in this manner, and run with hydraulic pressure of 150 p.s.i. at inlet 19, and with a flow of 1.7 gallons per minute through pump 8, established 80% to 95% of a perfect vacuum in chamber 32, with the average being about 89%. Under these conditions the bled-off flow was less than 1 percent of the flow delivered to operate the jack 4, and there was no noticeable impairment of operation, for the otherwise standard system involved.
The automatic oil-return system of the invention and its associated jet pump thus simply and efliciently provide for continuous scavenging of oil which leaks from the elevator actuating cylinder; this result is achieved by using only a small fraction or bleed from the same hydraulic pressure which creates the leakage. The scavenger system is automatically operative whenever the elevator is going up, and at other times when the main hydraulic pump is in operation.
While the principles of the invention have been described in connection with the above specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of the invention as set forth in the accompanying claims.
What is claimed is:
1. In a hydraulic elevator system including a main hydraulic pump, an actuating jack and a fluid storage tank, an improved automatic return system for returning hydraulic fluid which leaks from the actuating jack to the fluid storage tank comprising:
means attached to the main jack to collect the fluid which leaks therefrom, said collector means having an outlet for the fluid collected:
a constricted bleed connection from the main hydraulic pump output including a jet pump having first and second inlets and one outlet;
means connecting the first of said inlets to the output side of the main hydraulic pump;
means connecting the second of said inlets to the outlet of said collector means; and
means connecting the outlet of said jet pump to the liquid storage tank, so that whenever the main hydraulic pump is operating, the automatic oil return system will also be in operation.
2. The system of claim 1, in which said bleed constriction limits jet-pump flow to a relatively small fraction of the flow required for operation of said jack.
3. The system of claim 1, further including a check velve mounted within said second inlet of said jet pump so as to prevent oil from flowing from said pump toward said collector means.
4. The system of claim 3, wherein said jet pump is comprised of a T-shaped pipe fitting:
an input jet comprising a length of tubing of selected dimensions, and means for mounting said tubing within and substantially coaxially aligned with the cross bar of said T-shaped fitting;
an exhaust tube comprised of a length of tubing substantially larger in diameter than said input jet, and means for mounting said outlet tube within said fitting so that the longitudinal axis thereof is coextensive with the longitudinal axis of said input jet tube, and with the adjacent ends of said input jet and exhaust tubes spaced a preselected distance apart.
5. The system of claim 4 wherein the means for mounting said input jet tubing within said T-shaped fitting includes a first tubing flange adapted to thread into one end of the cross bar of said T-shaped housing, and a tubular bushing adapted to thread into the inside end of said first flange, said input jet tubing being telescopically fitted into said bushing and attached thereto.
6. The system of claim 5 wherein the means for mounting said exhaust tube within said pump housing includes a second tubing flange adapted to thread into the other end of the cross bar of said T-shaped housing, and a tubular bushing adapted to thread into the inside end of said second flange, said exhaust tube being telescop ically fitted into said second-mentioned bushing and attached thereto.
7. In a hydraulic system wherein a mechanism is driven by a hydraulic actuating device, which device is operated by hydraulic fluid supplied under pressure by a main hydraulic pump; an improved system for returning hydraulic actuating fluids which have leaked from said actuating device to the hydraulic system from which they escaped, comprising; means to collect the hydraulic actu ating fluid which has leaked from the hydraulic actuating device, said collecting means having an outlet for the liquid collected, a jet-type vacuum pump, having a high pressure input, an intake and an outlet, and means to connect the high pressure input of said jet pump to the output side of said main hydraulic pump, means to connect the intake of said jet pump to the outlet of said collector means; and means to connect the output side of said jet pump to a hydraulic reservoir which supplied the hydraulic system served by said main pump, so that the hydraulic pressure which is related to such liquid leakage also actuates the jet pump which pumps collected leakage back to the reservoir.
References Cited UNITED STATES PATENTS Re. 11,755 7/1899 Muir 103-262 1,474,454 11/1923 Telfer. 1,737,870 12/ 1929 Telfer. 2,136,239 11/1938 Ernst 92-172 XR 2,43 8,245 3/1948 Gregg 60-52 2,575,241 ll/l95l White.
EDGAR W. GEOGHEGAN, Primary Examiner US. Cl. X.R. 92-80; 103-262 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 9 421 Dated September 22, 1970 Inventor(s) G. NEELEY It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
Column 3, line 34, cancel "26a of tube 26 is critical,
but may be readily set by" and substitute therefor "26 is too great or too small the efficiency of the jet--- SIGNED hNb SEALED FE a 2 1971 15m Await:
M mum: E. SGHUYLER, .m. Awning Officer Goflhissioner of Patents