US3491697A

US3491697A - Hydraulic fuel oil pump or the like

Info

Publication number: US3491697A
Application number: US686391A
Authority: US
Inventors: Jorgen Hartvig Petersen
Original assignee: Danfoss AS
Current assignee: Danfoss AS
Priority date: 1966-11-29
Filing date: 1967-11-27
Publication date: 1970-01-27
Anticipated expiration: 1987-01-27
Also published as: NL6716121A; DE1553008B2; GB1180254A; ES347716A1; DE1553008C3; DK132096B; BE707104A; SE337079B; DE1553008A1; CH478989A; DK132096C

Description

Jan. 27, 1970 J. H. PETERSEN 3,491,697

HYDRAULIC FUEL OIL PUMP OR THE LIKE Filed Nov. 27, 1967 2 Sheets-Sheet 1 Jan; 27, 1970 J. H. PETERSEN 3,491,597

I HYDRAULIC FUEL OIL PUMP OR THE LIKE Filed Nov. 27, 1967 2 Sheets-Sheet 2 United States Patent Int. (:1. F04c 1/04, 29/00 US. Cl. 103-126 9 Claims ABSTRACT OF THE DISCLOSURE The invention relates to hydraulic pumps and particularly to the providing of a novel inlet chamber arrangement. The inlet chamber arrangement includes a centrally located inlet chamber to which a liquid such as oil is delivered through radially extending passages. A tangentially extending passage extends tangentially relative to the inlet chamber and connects the inlet chamher with the suction producing pumping elements. The tangentially extending passage causes the liquid in the inlet chamber to rotate and thereby provide certain advantage relating to the operation of the pump, including improved operation when the liquid supplied to the pump is at a relatively low level.

This invention relates to a hydraulic pump, especially a fuel oil pump having a suction port arranged in a vertical wall and a preliminary chamber preceding the suction port, the chamber being divided from the suction chamber by a partition with inlet ports.

A problem encountered in hydraulic pumps, especially fuel oil pumps, is the fact that air is separated in the suction chamber. When the liquid has been completely sucked in, the pump will sometimes only convey air. This produces cavitation noises in the gears and orifice pressure variations giving a pulsating flame; it also leads to the inadvertent operation of the pressure-dependent cut-off valve, disturbs flame control etc.

A hydraulic pump is known in which the suction port is arranged centrally and the inlet port consists of a slot extending in outward direction from the center, or of several bores situation on such a radial line. The inlet port is comparable to a passage the resistance of which varies with the liquid level in the suction chamber. The lower the liquid level drops, the higher the resistance opposing the flow of the liquid, and the more air is drawn off along with the liquid.

With this pump, the radial slot must point in upward direction during operation. Furthermore, difficulties are experienced where an eccentrically arranged suction port is used. The desired admixture of air and oil is the result of a pressure drop to which the oil is subjected. Quite apart from the desirability of avoiding pressure losses of any kind, there is the further disadvantage of disturbing noises which is also inherent in this mixing technique.

The present invention has for its object to draw off the air in a pump of the type referred to with a smaller loss of pressure and provides for a pump operating independently of its working position so long as the pump shaft is substantially horizontal.

This object is achieved, according to the invention, in that the preliminary chamber is axially symmetrical, the suction port is situated close to the periphery of the preliminary chamber and extends tangentially and ducts extending in outward direction from the preliminary chamber connect the inlet ports with the chamber.

The liquid entering the preliminary chamber through 3,491,697 Patented Jan. 27, 1970 the submerged inlet ports is caused to rotate by the tangentially arranged suction port. Itv is immaterial whether the suction port is in the lowest, highest or any other position. As soon as the liquid level has dropped sufliciently far for the duct communicating with the air space through its inlet not to contain any more liquid, the revolving liquid pulls air from the point where the air space and the duct meet. This takes place without any considerable loss of pressure or noise. The air is intimately mixed with the liquid because the most highly concentrated liquid is always present at the point where air is admitted since, due to centrifugal force, the unmixed liquid is forced upwards the periphery while the aerated liquid foam remains in the centre region of the preliminary chamber. In this region the foam cushion also attenuates noise created by the pump shaft.

The above-mentioned ducts preferably extend radially and are uniformly distributed over the circumference of the preliminary chamber. Advantageously, at least three ducts are provided. In this way, complete positional independence of the pump is achieved with a minimum of means.

Further, according to the invention, the longitudinal dimension of the inlet ports may be kept small in relation to their cross section. This increases their operational independence on the viscosity of the liquid. It is sufficient for the size of the inlet port to be adapted to the suc tion capacity of the pump.

The positional independence and uniform air admixture provided for by the invention are of particular importance for high-efiiciency pumps because even small variations of the prescribed position can impair the efficiency of such pumps considerably. Thus, further ac cording to the invention, the suction port in hydraulic gear pump leads to a suction chamber, known per se, which charges the gears from both sides.

The low pressure losses of the pump of the invention make it particularly suitable for constructions in which pressure losses have already been reduced as far as possible. Therefore, still further according to the invention, the delivery chamber of the pump surrounds the gears on both sides in known manner. This design also improves the hydraulic equilibrium of the gear.

A pump having the above-described characteristics is capable of operating with suction heads only 20 mm. below barometric pressure, i.e. up to about 710 mm. Hg. In this connection it is also important that adequate charging can still be achieved with these high suction heads, due to the intimate admixture of liquid and air. This could not be achieved with less intense admixture.

As for the constructive design it is advantageous for the preliminary chamber, the ducts and the inlet ports to be provided in a cap attached to the end of the pump.

It is also advantageous for a cover plate on the end face of the pump to contain a shaft bearing as well as the suction port communicating with the connection duct, and the suction and delivery chambers on one side of the gears. An intermediate plate between the gears and the pump housing may then be provided with the suction and delivery chambers on the other side of the gears. At least one of these plates may be produced by sintering, a very inexpensive process of manufacture.

The invention will now be described in further detail with reference to an embodiment thereof, illustrated by way of example in the drawings.

FIG. 1 shows an oil pump designed according to the invention in which cover, diaphragm and filter have been removed;

FIG. 2 shows a longitudinal section along the line AA of FIG. 1;

FIG. 3 is a part-sectional view along the line BB of FIG. 1;

FIG. 4 is a part-sectional view along the line CC of FIG. 1.

The ducts 1 connect the pump intake with a distribution chamber 2 arranged between a cover 3 and a filter 4. The oil entering the chamber is sucked into a suction chamber I through the filter 4, the suction chamber being provided with a rubber diaphragm 5 which, together with the air space behind it, is capable of equalizing the pressure fluctuations of the pump. From the suction chamber I, oil passes through the inlet ports 6 and radial ducts into an axially symmetrical preliminary chamber II. The last-mentioned parts are provided in a cap 7 which is mounted on the pump by means of bolts 8, a plate 9 being interposed. The bolts 8 also hold a cover plate 31, a gear plate 19 and an intermediate plate 32 to the pump housing 33. The inlet ports 6 are bores in a surface inclined by 45 to the axis of the shaft. Therefore the projection of the port cross-section on the duct cross-section, and also on the end face of cover plate 31, is smaller than the effective cross-section of the port. The bores extend coaxially, so that the ports 6 virtually have no longitudinal dimension which would make their efficiency depend on viscosity.

In the cover plate 31 is provided aduct 11 which constitutes a tangential continuation of the preliminary chamber 2 and forms a suction port 36 on the end face of the cover plate 31. The duct 11 leads through another bore 12 into the inlet chamber of the pump which latter is formed by a toothed gear 16 and a toothed annulus 17. Behind the bore 12 the oil stream divides. One part flows, through a connection duct 13 in the cover plate, to a suction chamber 14 from where the suction tooth gaps 15 are charged on one side. The remaining oil flows, through a bore 18, and a connection duct 20, to another suction chamber 21 from where the suction tooth gaps 15 are charged on the other side. There the oil is conveyed to the delivery side. From the delivery tooth gaps 22 the oil is discharged in two part-streams through the

ducts

23, 24. The gears are hydraulically relieved due to the fact that oil pressure is the same on both sides. The oil passes through

connection ducts

25, 26 into collecting

ducts

27, 28 of the gear plate 19 from where it flows through a bore 29 passing through the gear plate 19, the intermediate plate 32 and the housing 33 into a connection duct and to the delivery valve of the pump.

In the cap 7 are provided the preliminary chamber II, the three ducts 10 and the inlet ports 6. The cover plate 31 supports the pump shaft 34; it also contains the

oil ducts

11, 12, 13, 14, 24 and 25. In the intermediate plate 32 are provided the

chambers

20, 21, 23 and 25.

When oil is sucked in during operation through the tangential duct 11, the oil in the preliminary chamber II begins to rotate. When the level of the oil has dropped below the point 35, the revolving oil takes along the air induced through the upper inlet port 6 and the upper radial duct 10. This air is intimately mixed with the oil, so that it cannot do any harm while being conveyed through the pump. Due to centrifugal force, a lighter air/ oil mixture forms in the centre of the vortex, so that a very concentrated volume of oil becomes available in the region of the mixing point 35. Also the suction port 36 is situated in this region of increased oil concentration. The oil vortex is fed with fresh oil from below and can thus maintain the above-described condition. In this way it becomes possible quickly and reliably to suck off surplus air, with a minimum loss of pressure and without appreciable noise. Due to the intimate admixture with oil, no disturbance in subsequent parts of the pump system needs to be anticipated.

It is obvious, furthermore, that it is immaterial for the operation of a pump of this design whether the pump assumes the position illustrated in the drawing or is turned about its horizontal axis by any desired amount, for several inlet ports 6 and ducts 10 are available for the entry of oil and air, and the tangential suction duct 11 is capable of conveying the oil and initiating its rotation in any angular position.

I claim:

1. A hydraulic pump comprising, a casing, a horizontally extending shaft rotatably supported by said casing, pumping means attached to said shaft, a plate member attached to said casing adjacent said pumping means, a cap member attached to said plate member on the opposite side thereof from said pumping means, said cap member forming an inlet chamber having a centrally disposed portion and a plurality of radially extending duct portions, each of said duct portions having an inlet port at its radial extremity, a suction passage formed in said plate member providing fluid communication between said inlet chamber and said pumping means, said suction passage extending tangentially relative to the periphery of said centrally disposed portion of said inlet chamber.

2. A hydraulic pump according to claim 1 characterized by said duct portions extending radially outwardly and being symmetrically arranged.

3. A hydraulic pump according to claim 1 characterized by there being at least three of said duct portions.

4. A hydraulic pump according to claim 1 characterized by the plane of each of said inlet ports being at an angle of approximately 45 relative to the longitudinal axis of the pump.

5. A hydraulic pump according to claim 1 characterized by fluid inlet passages on opposite sides of said pumping means for admitting a fluid to both sides of said pumping means, said fluid inlet passages being in fluid communication with said suction passage.

6. A hydraulic pump according to claim 5 characterized by fluid outlet passages on opposite sides of said pumping means for receiving fluid discharged from both sides of said pumping means.

7. A hydraulic pump according to claim 1 characterized by said cap member having the form of a shell-like gap, and means for attaching said cap to said plate mem- -8. A hydraulic pump according to claim 6 characterized by said plate member having the form of a cover plate, said shaft having one end thereof rotatably supported in said cover plate, and said cover plate having a portion of said fluid inlet and outlet passages formed therein.

9. A hydraulic pump according to claim 8 characterized by a side plate adjacent said pumping means on the opposite side thereof from said plate member, said side plate having a portion of said inlet and outlet passages formed therein.

References Cited UNITED STATES PATENTS 2,751,847 6/ 1956 Erikson. 2,775,206 12/ 1956 Connelly. 2,966,118 12/ 1960 McAlvay. 3,162,129 12/1964 Erikson. 3,312,177 4/1967 Eckerle et al. 3,343,494 9/1967 Erikson et al.

ROBERT W. WALKER, Primary Examiner W. I. GOODLIN, Assistant Examiner US. Cl. X.R. 230207