US1742597A

US1742597A - Rotary pump

Info

Publication number: US1742597A
Application number: US192850A
Authority: US
Inventors: Hoke William Eben
Original assignee: Individual
Current assignee: Individual
Priority date: 1927-05-20
Filing date: 1927-05-20
Publication date: 1930-01-07
Anticipated expiration: 1947-01-07

Description

Jan. 7, 1930. w, E HQKE 1,742,597

ROTARY PUIP Y Fld lay 20;. 192'7 .l 5 ShestsFSheet 1 INVENTOR ATTORNEYS Jan. 7, 1930. w. EjHoKE 1,742,597

ROTARY PUIP Filed lay 20. 1927 3.Sheets-Sheet 2 INVENTOR ATTORNEYS Jan. 7, 1,930. w, E, Hem.; 15742,',597

f ROTARY PUIP Filed un; 2o. 192'?l s sheets-sheet s I Q/ 7*, i 5. E I mvlToR .lzzV "Bla/g ATTORNEYS Patented Jan. '7, 1930 UNITED s're'rias PATE-NT OFFICE WILLIAM. EBEN ,HOKE F BALTIMORE, MARYLAND, ASSIGNOR TO JOSEPH MERCA- DANTE, OF NEW YORK, N. Y.

vno'ran'z PUMP Application mea my 2o,

This invention relates to rotary iumps of the General type disclosed in the roh Patent o. 1,495,411, issued May 27, 1924, and it includes not only improvements in pumps 0f this character, but also improvements in gears suitable for use in rotary pumps and improvements in'methods of making such gears.v

Rotary pumps of the character described in the said Patent No. 1,495,411 comprise a pump chamber casing enclosing intermeshing lgears- In the operation of the pump, the

fluid being pumped or compressed enters the spaces between the gearteeth as they disengage and the Huid is discharged from these spaces into the high pressure side of the system. As the gear teeth come into mesh. all of the fluid occupying the tooth spaces with thcexception of the clearance spaces is expelled, and where a gas is being pumped, a suitable cooling fluid such as oil is relied upon to prevent communi- .cation between the high and low pressure sides of the pump system through the clearance spaces. A' considerable quantity of sealing fluid is ordinarily employed for this purpose, and even at best there is some leakage of the pumped fiuid from the'high pressure side of the system to the low pressure side. The use of a considerable quantity of sealing fiuid presents a number of difficulties which have heretofore been considered unavoidable. The normal action of the pump causes the sealing fluid to foam, and various attempts have been made to preserve the quality of the scaling fluid, as b v cooling the same. Furthermore, it is ver v difiicult. if not impossible, to prevent some ot' the scaling fiuid from hecoming so intimately associated with the pumped fluid as to render the separation of these n'iaterials impossible except by the use of special apparatus designed for this purpose. p

Une of the objects of my invention is to provide a rotary pump in which it is unnecessary to use the usual quantity of sealing fluid, it beingT necessary'to merely employv enough oil to lubricate the parts. A further object of this invention is to provide a rotary pump of higher efficiency than those heretofore used, arid this b v virtue of the fact that gears of an improved character are employed, the gears 1927. Serial No. 192,550. v

vide a. gear pump having an inlet port extend- A 'ing'substantially to the center line, passing through the axes of the gears, whereby the enlarging tooth spaces remain in communication with the fluid supply until the spaces are entirely filled.

A further objectis to provide a rotary pump having spirally cut gears and a discharge' or relief port extending substantially to the vertical center line passing through the axes of the gears, to thereby prevent trapping of liquid between intermeshing teeth as they come together. This prevents the hammering action ordinarily encountered With pumps of this type,a11d renders the operation of thepump noiseless. Still another object of my invention is to provide gears for rotary pumps having teeth, the profiles and root outlines of which comprise a continu- -ous development or generation of the gear tooth curve, and as stated above, my invention includes an improved method of making the gears just described.

My improved method includes the' use of a reversibly symmetrical rack-like cutter for forming the improved gears, the gears being formed in such a manner that no appreciable clearance space is provided. It will be understood, however, that gears of the improved type can be made by the use of means other than this particular form of gear cutter.

The various objects and advantages of my invention will be more apparent upon considering the following detailed description, which is to be taken in conjunction with the accompanying drawings, in which I have illustrated certain embodiments of my invention. In the accompanying drawings,

Fig. 1 is an enlarged fragmentary View of two intermeshing gears made in accordance with my invention;

Fig. 2 is an enlarged fragmentary view of one of the improved gears and a cutter suitable for making the gear;

Figs. 3 and 4 are enlarged fragmentary views of other forms of gear cutters;

Fig. 5 is a vertical section -view taken on line 5-5 of Fig. 7;

Fig. 6 is a transverse section view taken on line 6-6 of Fig. 5, showing details of construction;

Fig. 7 is a transverse section view takenon lineT--T of Fig. 5, showing details of construction y Fig. 8 is an end elevation of the pump shown in Fig. 5;

Fig. 9 is a transverse section view taken on line 9--9 of Fig. 5, showingdetails of construction;

Fig. 10 is a transverse section view taken on line 10-10 of Fig. 5, showing the construction of the pump casing;

Fig. 11 is a transverse section view taken on line 11-11 of Fig. 5, showing details of construction; and

Figs. 12 and 13 are perspective views of a spirally cut gear made in accordance with my invention.

The accompanying illustrations-of certain embodiments of my invention show gears having teeth the profiles and root outlines of which comprise the continuous development of a gear toothcurve, one of the characteristics of the gears being that the crowns of the teeth of one gear are adapted to bottom or make contact with the corresponding root portions of the gear inter-meshing therewith. In other words, the gear teeth are so shaped that all portions thereof, from the lowest points ofthe roots to the highest points of the crowns. cooperate in gear action during the rotation of the inter-meshing gears. In ordinary gears, the root circle, which bounds the bottoms of the tooth roots, is lower than the working depth circle or the circle bounding the extent to which a tooth crown on a coopera't-ing gear enters a tooth root. Thus the portions of ordinary gear teeth below the working depth circles, as well as the portions of the crowns tangent to the adendum circle, do not cooperate in gear action because they do not follow developments of any gear-.tooth curve. In the gears of the present invention, the root circles and working depth circles are coincident, the tooth profiles and root outlines being continuous developments of a gear tooth curve throughout. Thus gear action takes place over the entire surface of each gear tooth during the rotation of the cooperating gears.

The gears ofthe present invention are preterably formed to engage without back-lash, that is, the thickness of each tooth is equal to the tooth space into which it meshes when measured on the pitch circle.

In Fig. 1for example, I have illustrated a gear A, meshing with the gear B. and the tooth profiles 1 and the root outlines 2 of gear A are continuous developments or generations of the gear tooth curve. The same is true of the tooth profiles 3 and the root outbe made by utilizing a reversibly symmetrical rack-like cutter having sharp pointed teeth.

The teeth and spaces of the rack are equal and symmetrical, or in other words, each tooth and the adjacent space are bounded by similar and equal lines of alternating reversion. It may be stated that if two racks of this character be fitted together, the teeth of one will exactly tit and fill the spaces of the other. One is the complement of the other, and the teeth and spaces will be exactly equal as measured on the pitch line. Gears cut by means of such a rack cutter are conjugate to the rack and to each other, and inasmuch as no clearance is provided, each tooth is adapted to make contact at a plurality of points Ywith the intermeshing gear.

For example, one ofthe teeth of gear B in Fig. 1 is shown making contact with gear A at 5,- 7 and 8. The gears are shown in the preferred adjusted position in which there is no back-lash.

The teeth of the rack cutter may be of any desirable form, the important consideration being that the cutter should be reversibl symmetrical. In Figs. 2, 3 and 4, I have i lustrated forms of teeth different from the sharp pointed teeth just described. The teeth shown in Fig. 2 are provided with straight sides 9, with a rounded crown 10, and a correspondingly rounded root portion 11. The tooth shown in Fig. 3 is provided with straight sides 9', with a. flat crown 10', and a 'lat root portion 11. The tooth shown in Fig. 4 is provided with curved sides 9, with a rounded crown 10 and correspondingly rounded root portions 11". The involute system of tooth curvescan be employed using any portion of the curve with the result that the gears have all of the advantages incident to gears having teeth of the involute type. Other standard systems may likewise'be employed.

In Figs. 5 to 11 inclusive, I have illustrated one embodiment of my invention as applied to rotary pumps. In these figures, 12 represents a portion ot' a pump casing of any suitable form, it being understood that the pump gears 13 and 14 are enclosed within the casing, a part of which is shown at 12. The gear 14 is keyed or otherwise fixed to a shaft l5 journaled in the casing 12 and in hearing

plates

16 and 17. The shaft 15 projects through the casing wall and is driven by any suitable means (not shown). Suitable packving 18 is provided around the shaft 15, 1n accordance with usual practice. The gear 14 meshes with gear 13 and is carried by a shaft 19 journaled in the bearing

plates

16 and 17.

n supply the fluid directly to .the tooth spaces of the

gears

13 and 14. As the gear teeth disengage, the fluid is drawn into the enlarging tooth spaces until they are substantially filled with the fluid. Thereafter, the fluid is trapped in these spaces by the curved surfaces 2l and 22 of the segmental housing 20. As the advancing gear teeth leave the extreme portions of the segmental housing, the fluid is discharged into the interior of the pump casing.

I prefer to form the passage 24.in such manner that the delivery end thereof extends substantially to the center line of the pump passn through the axes of the

gears

13 and 14,A as est shown in Fig. 6. Vith this arrangement, it is possible to fill the tooth spaces completely before communication therewith is cut olf by the

curved portions

21 and 22 of the segmental housing 20. The

gears

13 and 14 are spirally cut and of the type above described and illustrated in Figs. 1 to 4 inclusive, and 12 and 13. The pitch of the spirally cut teeth is preferably such that one pair of cooperating teeth does not become entirely disengaged until the next pair begins to come into engagement. Accordingly, there is never a through passage along the gear tooth spaces from the interior of' the pump casing to the fluid supply passage 24.

In Figs. 12 and 13, I have attempted to illustrate some of the characteristics of my improved gears which render them particularly valuable as the movin elements of a rotary pump. In these two hgures, which are perspective views of a spirally cut gear made in accordance with my invention, the dotted line represents the line of Contact between two intermeshing gears of this form. Fig. 13 shows the gear of Fig. 12 in a slightly different position. As shown by the dotted line, the line of contact or line of seal between two intermeshing gears of this form is continuous, and in the particular instance illustrated, extends across the crowns of two adjacent teeth. lVith gears of ordinary construction, the line of seal or line of contact is not continuous; it is interrupted at the crowns of the interengaging teeth due to the clearance space.

Vith the particular gear shown in Figs. 12 and 13, the line of contact or line of seal, although continuous, is made up of a number of parts, seven parts being shown in Fig.

13 as a., b, c, (l, e, f and g. Upon referring to Fig. 12, it Will be noted that the portion g of the line of seal or line of Contact is in alignment with the portion c, these two portions being on corresponding faces of adjacent teeth. The particular gear illustrated in Figs. 12 an-d 13 is of the involute form,

'the tooth profiles and root outlines being a continuous development or generation of the gear tooth curve.

Referring again to Figs. 5 to 11 inclusive,

it will be noted that the inner bearing plate 16 is provided on the inner face thereof with a depression 25 communicating With a pipe 26 bymeans of a channel or passage 27. Lubricating or sealing fluid can be supplied to the depression 25 through the pipe 26 and where the pump is used for the purpose 0f compressing a gasified refrigerating medium such as sulfur dioxide, the usual sealin fluid such as oil can be supplied to the 4pipe 26 from the interior of the pump casing. T he sealing Huid or lubricating fluidv may gain access to the

gears

13 and 14 through small passages'28 and 29, best shown in Figs. 7, 9 and 10. These passages-communicate with those portions of the gears 7 in contact with the segmental housing 20, and the sealing fluid may serve the purpose of compressing the gaseous fluid trapped in the tooth spaces.

lVhere my invention is employed, it is not necessaryto use as much sealing fluid as is ordinarily employed; it is quite sufficient to merely employ enough of the fluid to lubricate the gears. This desirable result is made possible because of the form of the gear teeth which, as pointed out above, are capable of 'forming a continuous line of seal from one end to the other.

In order that all of the liquid in the tooth spaces may bereadily expelled as the gear teeth come together, I provide an exhaust port 30 in the outer bearing plate 17. This port may extend substantially to the vertical center line passing through the axes of the gears, thus permitting all of the liquid in the gear tooth spaces to be discharged, thus eliminating the trapping of any of this liquid, as is ordinarily the case in rotary pumps. It is ordinarily impossible to locate the discharge port very close to the vert-ical center line of the pump because in the ordinary pump this would result in the escape of the pumped .fluid from the high pressure side of the system to the loW pressure side through the gear tooth spaces. This discharge is eliminated by the use of gears made in accordance with myrinvention'.

It. is to be understood that my invention is not limited to the particular embodiments illustrated and described, but include such lnodifications thereof as fall within the scope of the appended claims. For example, my improved gears can be formed by using cutters other than those herein described in detail; my invention can be applied to .gears of any type, and the details of the pump mechanism can be modified and in some instances even eliminated Withoutsacrificing all of the 5 advantages of my invention.

I claim: v

1. In apump, the combination with the pump chamber casing, of intermeshing sp1- rally cut gears, means for introducing the lo pumped fluid into spaces between intermeshlng teeth at one end of the gears, means for introducing a sealing liquid into said spaces, and means permitting escape of said liquid from between the teeth at the point Where the opposite end of the teeth are completely or fully intermeshed;`

2. In a pump,'the combination with the pump chamber casing, of intermeshing spirally cut gears, means for introducing the pumped fluid intospaces between intermeshing teeth at one end ofthe gears, means for introducing a sealing liquid into said spaces, and means at the opposite ends of vthe teeth for receiving sealing liquid forced from between intermeshinf teeth at said opposite ends, said means being located at a, point where the teeth at said opposite end are fully intermeshed.

3. In a pump, the combination with the pump chamber casing, of intermeshing spirally cut gears, means for introducing the pumped fluid into spaces between intermeshing teeth at one end of the gears, means for introducing a sealing liquid into said spaces,

and end plates enclosmg the ends of the gears, the plate at the end opposite the point of admission of pumped fluid having a relief recess therein located at the point at which the adjacent ends of the teeth are fully in- 4 termeshed.

4. In a pump, the combination with the pump chamber casing, of intermeshing spirally cut gears, means for introducing the pumped Huid into spaces between intermeshing teeth at one end of the gears, means for` introducing a sealin liquid into said spaces, and end plates enclosing the ends of the gears, the plate at the end of the gears remote from the point of admission of the pumped fluid having a duct therein extending from its eX- terior face to a point on its interior face in registry with the point at which the teeth fully intermesh at that end of the gears.

In testimony whereof I aiix my slgnature.

WILLIAM EBEN HOKE.