US3071313A

US3071313A - Compressor construction

Info

Publication number: US3071313A
Application number: US830338A
Authority: US
Inventors: Zenas V Weisel
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-06-18
Filing date: 1959-07-29
Publication date: 1963-01-01
Anticipated expiration: 1980-01-01

Description

Z. V. WEISEL COMPRESSOR CONSTRUCTION Original Filed June 18, 1956 Jan. 1, 1963 2 Sheets-Sheet l R 0 m m N 1 Jan. 1, 1963 2. v. WEISEL 3,071,313

COMPRESSOR CONSTRUCTION 2 Sheets-Sheet 2 Original Filed June 18, 1956 v INVENTOR. ZE/VAS 1 WE ASE 1.

United States Patent Ofitice 3,071,313 Patented Jan. 1, 1963 3,071,313 COMPRESfiSR QQNSTRUCTEGN Zenas V. Weisel, I39 N. Ave. 66, Los Angeles 42, (Iaiii'. Uriginal application June 15, 1956, Ser. No. 592,195, new Patent No. 2,916,198, dated Dec. 3, 1959. Divided and this application July 29, 1959, Ser. No. 839,338

5 (Jlaims. (1. 230--127) This invention relates to centrifugal compressors and pumps and more particularly to a device of the class mentioned featuring unusual compactness and low cost while retaining the efliciency characteristics of high performance devices having an annular vaned diffuser assembly or one having a volute scroll discharging into a high efficiency narrow angle diffuser cone. The invention has particular use in applications'where it is desired to achieve eflicient operation with minimum energy losses over a wide range of flow rates and operating speeds. I 1

The subject matter of the present-invention has-been divided from applicants co-pending application for United States Letters Patent Serial No. 592,105, filed June 18, 1956, entitled-Turbine compressorApparatus, now Patent 2,916,l98 grante dDecember 8, 1959.

The present invention was developed to meet the exacting space restrictions and performance requirements encountered in providing a high efficiency centrifugal compressor for an automobile air conditioning and supercharging system of sufficient flexibility to meet the rigorous requirements as to capacity, operating characteristics and space and cost requirements of an engine propelled road vehicle. Such a system is the subject matter of my co-pending application for United States Letters Patent Serial No. 423,936, filed April 19, 1954, now Patent No. 2,898,745, granted August 11, 1959. However, it will be appreciated that the novel principles of the compressor developed to meet the requirements of that application have general application in numerous other operating environments subject to similar widely divergent operating requirements.

Designers of centrifugal type compressor structures have long been aware of the benefits to be gained from the pressure rise of the flow passing through the diffusing vanes which vanes progressively reduce the velocity of the compressed fluid issuing from the periphery of the rotor thereby to convert kinetic energy into pressure with minimum energy losses. However, the use of such structures is accompanied by certain disadvantages of importance in compressor applications of the type here under consideration.

For example, diffuser structures are not only costly but increase the bulk of the compressor to an extent not always tolerable. Of even greater importance, such diffuser structures operate efficiently and effectively only within a relatively narrow range of How and pressure conditions. Additionally, when the compressor is not operating within the optimum design range conditions, flow through the diffusers is apt to produce sounds of various magnitudes and frequencies highly irritating and objectionable to persons in the vicinity. This factor alone is suflicient to render the use of such diffusers highly objectionable in a motor vehicle where the driving turblue of necessity operates over a very wide speed range.

Another highly objectionable disadvantage of prior volute-type centrifugal compressor designs when an attempt is made to use them on a motor propelled vehicle is the presence of the long narrow angle diffuser cone at the terminal end of the scroll chamber and used to avoid excessive energy losses.

In view of the above factors characteristic of prior art centrifugal compressor constructions, it is a primary object of the present invention to provide a simple, low

cost, rugged very compact yet highly efficient centrifugal compressor obviating the need for an annular vane diffuser surrounding the compressor impeller and so constructed and arranged as to convert kinetic energy in the high velocity flow issuing from the rim of the rotor to pressure energy within a minimum of spaced and attended by minimum energy losses over an extremely wide range of operating conditions.

These objectives are attained according to the present invention by conducting the high velocity compressed air issuing from the rotor rim tangentially into a scroll chamber offset closely beside the rim of the rotor discharge causing the high velocity gas to flow in a helical path into a short, wide angle diffuser cone. The centrifugal energy thereby imparted to the compressed particles is availed of to expand the rapidly moving gas into the wide angle diffuser cone in a highly efficient manner. The highly objectionably acoustical characteristics of diffuser systems commonly used between the rotor and the scroll chamber under conditions outside the narrow design range limits of such systems is thereby entirely avoided. Hence, it will be appreciated that all features and aspects of the scroll chamber structure mutually cooperate in providing a highly superior and unusually adaptable compressor.

The efficiency achievable with a compressor constructed according to this invention will be substantially equal to that of high performance annular diffuser ringtype compressors and is attained by a structure the overall diameter of which is only one-half to two-thirds as large. Likewise, as compared with high performance volute-type having a long narrow cone diffuser, the present construction operates with equivalent efficiency while eliminating a diffuser cone having a length two to five times the diameter of compressor proper.

Accordingly, it is an object of the present invention to provide an improved, low cost, high efficiency centrifugal compressor or pump design operating efficiently over a Wide range of operating conditions and in a minimum of space.

-Another object of the invention is the provision of an unusually compact centrifugal compressor having high performance and low noise output over a Wide range of operating conditions.

Another object of the invention is the provision of a centrifugal compressor having an outlet annular passage free of vanes and the like flow directing means arranged to discharge the fluid being compressed tangen- I tially into a volute shaped scroll chamber offset slightly to one side of the rotor rim and provided at its discharge end with a diffuser cone of relatively great angle and short axial length.

Another object of the invention is the provision of a centrifugal compressor wherein the high velocity gas issuing from the rotor is discharged tangentially into a scroll chamber to swirl the gas through a helical path terminating in a relatively short axis-wide angle diffuser chamber wherein kinetic energy is converted quickly and efficiently into pressure energy with minimum energy loss.

These and other more specific objects will appear upon reading the following specification and claims and upon considering in connection therewith the attached drawing to which they relate.

Referring now to the drawing in which a preferred embodiment of the invention is illustrated:

FiGURE 1 is a side elevational view of a turbo-cornpressor unit, the compressor portion of the unit being shown in longitudinal section and incorporating the features of the present invention;

FIGURE 2 is a transverse sectional view taken generally along line 2-2 on FIGURE 1 and showing the volute scroll chamber and the diffuser cone of the FI URE l compressor; and

FIGURES 3 to 6 are diagramatic views of diffuser cones of both the narrow-angle type long used at the discharge end of scroll chambers and the wide angle, relatively short diffuser cone of this invention.

Referring now more particularly to FIGURES l and 2, there is shown a turbo-compressor unit including a turbine assembly 14 suitably secured to one end face of compressor housing 15 as by bolts 16. The turbine runner (not shown) and the compressor rotor 23 are suitably fixed to a common supporting shaft 13 journaled in

bearings

17 and 18 mounted in known manner at the opposite ends of a bore 19 formed axially of a supporting cone 56. This cone is rigidly secured to casting 57 clamped against one end face of compressor housing 15 by bolts 16. The constructional details of casting 57 and of turbine 14 form no part of the present invention and for this reason need not be described here. Full details of each are to be found in the above-identified co-pending application Serial No. 592,105, now Patent No. 2,916,198. However, it is appropriate and germane to point out that turbine 14 is designed to operate efliciently over a wide variation in the flow of the driving fluid readily regulatable by means of a unique valving mechanism mounted within the turbine casing and adjustable through trunnions 37 projecting through the turbine casing. Secured to the outer ends of these trunnions are a pair of operating

arms

48, 48 having socketed lost motion connections with the outer ends of a rigid operating arm 53. This latter arm is journaled on a stub shaft 53 secured to a bracket 54 rigid with casing 14 or any other fixed support. Rotation of arm 53 about the axis of shaft 53' serves to adjust the position of the

arms

48, 48 of the associated valve members thereby to vary the input and speed of the turbine runner employed to drive compressor rotor 23.

Driving shaft 13 is formed with an integral flange 22 to the opposite faces of which the turbine runner and compressor rotor 23 are rigidly secured, as by

common fastener bolts

24, 24. Rotor 23 is provided with suitable vanes 66 projecting axially from the rotor hub and having their inlet ends in communication with gas inlet passage 58. The peripheral tips of vanes 66 discharge into a carefully designed annular passage 68 formed between generally complemental

arcuate surfaces

62 and 63. The disposition of annular passage 68 in its relationship to the volute or scroll passage 69 is of very considerable importance for reasons which will be explained in detail presently. To be noted in particular is the fact that the arcuate passage 68 discharges tangentially into the gradually expanding and volute shaped chamber 69, the axis of which is offset laterally to one side of passage 68 with the result that the high velocity gases issuing from the rim of compressor rotor 23 are caused to rotate in a gradually expanding helical path toward the outlet end of the scroll chamber proper. The described path taken by the high velocity gases is indicated by the helical arrows in FIGURE 2.

The flow path taken by the fluid from its point of discharge from the rim of rotor 63 until it exits from the wide angle bell mouth diffuser outlet 70 may be described as including a smooth-surfaced volute chamber encircling the rotor axis and offset axially closely beside one face of the rotor. This volute chamber includes a fluid receiving portion 68 opening radially from the rim edge of the rotor and extending along the circumference thereof and effective by reason of its shape to discharge the fluid tangentially into the side of a long narrow volute cone spaced axially to one side of the rotor rim. The length of this long narrow angle cone corresponds substantially to the full circumference of the rotor and its larger end opens directly into the smaller end of the wide angl diffuser or bell mouth outlet wherein the high-velocity helically flowing fluid advancing along the cone expands in a highly eflicient manner to convert kinetic energy to pressure energy without any appreciable energy loss. Preferably, the longitudinal axis of the bell mouth outlet diffuser 70 is straight and tangential to the axis of volute passage 69 at the point of merger therewith.

It is pointed out that the gas or air to be compressed enters the compressor through annular passage 58 and passes through the throat of an accurately machined ring 60 held assembled within an axial passage of housing 15, as by threads 61. The accurately finished peripheral surfaces 62 of ring 60 conform generally with the shape of an annular groove 63 formed in one face of septum disc 64 securely supported against a shouldered recess 65 opening axially through one end face of the compressor housing.

The outlet end of scroll chamber 69 merges smoothly with the inlet of a diffuser cone 70 characterized in that it is inordinately short and in that its bell-shaped interior flares abruptly. More specifically, it is pointed out that diffuser cone 70 is so short that it terminates substantially at the peripheral rim of the compressor casing and in that its side walls have an included angle of approximately 40 degrees in the design illustrated in FIGURES 1 and 2. It will be understood that this angle may be varied over a relatively wide range depending upon the operating conditions of the intended application and in particular upon the volume and velocity of the flow being handled and the overall eflicicncy objective. For example, wide angle diffuser cones used in combination with the type of volute chamber and tangential vaneless diffuser passage herein described and operating in accordance with the principles of this invention vary generally between an included angle of 30 degrees to 60 degrees.

Referring now more particularly to FIGURES 3 to 6, there is depicted diagrammatically some of the more important factors of controlling importance and explanatory of the novel principles of the present invention in contrast with the principles characteristic of prior compressor scroll chambers. Also depicted are reasons why a compressor constructed as described above operates at high efliciency owing to the mutually cooperating design characteristics of the principal components of the scroll chamber assembly and despite the absence of diffuser vanes in the inlet to the scroll chamber.

Referring first to FIGURE 3, there is shown a typical prior art diffuser cone 75 having its narrow inlet end 76 connected to a volute chamber of conventional type located radially beyond and in the same general plane as the compressor rotor. It is well known that minimum losses and optimum results are achieved when such a diffuser cone has an included angle between its opposite sides of approximately 7 degrees. Such shallow angled diffuser cones must be relatively long to achieve eflicient conversion of kinetic energy into pressure energy at the discharge end of the cone and characterized by a necessary length of two to five times the overall diameter of the compressor.

If an attempt is made to convert the kinetic energy to pressure energy in a shorter distance by the use of a shorter wider-angle cone, very serious losses occur. For example,- let it be assumed that a short, steep-angled diffuser cone 77 is substituted in place of cone 75 shown in FIGURE 3 under the same flow conditions. The long, narrow angle cone affords suflicient time for the high velocity gases flowing parallel to the cone axis to expand outwardly as they advance and to be converted into pressure energy without substantial energy loss. This required time factor is obtained only at the expense of a long narrow cone. If an attempt is made to convert the velocity energy to pressure energy by use of a shorter wider-angle cone, constructed as illustrated in FIGURE 4 for example, serious losses inevitably follow. This is because of the lack of time afforded for the required expansion. There results turbulent eddy flow and high losses as is indicated by arrows 78 in FIGURE 4.

Referring now to FIGURE 1 showing diagrammatically the transfer of the high velocity gases issuing from the rim of the compressor impeller, it will be noted that these high velocity gases are conducted through annular passage 68 thence tangentially into the rim portion of volute chamber 69. In consequence, these high velocity gases immediately swirl helically at high velocity as they ad- Vance toward the outlet end of this chamber. Due to the described tangential flow of the gases into the volute there is no tendency to circulate part of the high velocity gases in one direction and part in another as is true with respect to conventional volute chambers located radially beyond the tip of the compressor rotor.

Accordingly, in the manner described, there is imparted to the high velocity gases swirling within the volute a radial force component indicated by arrows 79 in FIG- URE 6. It will therefore be apparent that upon the emergence of these spiraling high velocity gases into wideangle diffuser cone 70, the entire stream expands naturally and under its own energy impetus free of eddies and conforming in shape with the generall bell-mouth curvature of the diffuser cone while simultaneously converting kinetic energy present into pressure energy Without substantial loss.

Summarizing the foregoing and completing the analysis, reference is had to FIGURE 5 showing a long narrow angle diffuser cone having its entrance in registry with the entrance of an equivalent short wide-angle diffuser cone of the invention and wherein both cones have the same final discharge diameters. As noted, the narrow cone has a 7 degree included angle whereas the short cone has a typical included angle of 40 degrees.

Let it be assumed that a particle of gas 80 enters the longer cone in a straight line parallel to the axis of the cone and that a similarly positioned particle of gas enters the shorter cone at the same axial velocity but traveling in a helical path.

The same particle 80 entering the wide cone in the same position will, under the impetus of centrifugal forces, have moved radially outward very quickly to the position 80 while advancing axially of the cone by the relatively short distance L as compared with the many times longer axial travel L for the first mentioned particle 80. The radial outward force component 79 forces particle 80 outward the distance R equal to distance R, in a shorter interval of time and shorter axial travel distance L. Distance R representing the net radial travel of the second particle is observed as being identical with the radial distance R traveled by the first particle in the long cone. The net energy loss in these two tends to favor the shorter diffuser cone of this invention owing to smaller skin friction losses.

In further explanation of the high efficiency flow occurring in the short wide angle diffuser cone, it is to be noted from FIGURE 6 that the expanding generally axial flow path taken by the expanding gas is represented by the arcuate line 82 having a center indicated at 83. It will be understood that this general flow path results from the cone design and from centrifugal forces 79 created by the rapid helically flowing gas stream as this stream expands along a bell mouth-like envelope each axial element of which lies along a curve represented by are 82 having a focal point 83.

While the particular compressor construction herein shown and disclosed in detail is fully capable of attaining the objects and providing the advantages hereinbefore stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as defined in the appended claims.

I claim:

1. A compact centrifugal pressure apparatus adapted 6 to operate efiiciently over a wide range of operating speeds and a wide range of flow rates, said apparatus having a housing, a centrifugal rotor rotatably supported in said housing having an axial fluid inlet and an annular discharge from the peripheral rim having a vaneless volute chamber formed therein and offset axially closely to one side of the rim of said rotor, said vaneless volute chamber including an annular fluid receiving portion and a downstream fluid discharging portion, said annular fluid receiving portion having a surface arranged to receive fluid from said rotor rim and to discharge the same axially of said housing and tangentially into said downstream discharge portion of said volute chamber without appreciable energy loss, said downstream discharge portion substantially encircling the axis of saidrotor and having a long narrow upstream cone portion terminating at the larger end thereof in a bell mouth diffuser outlet, said bell mouth diffuser outlet having an outward flare in excess of 30 degrees and effective in cooperation with said long narrow cone portion to convert the high velocity swirling stream of fluid advancing axially of said cone portion and of said bell mouth diffuser outlet into pressure energy by the time the fluid reaches the larger end of said bell mouth outlet.

2. A compact centrifugal pressure apparatus as defined in claim 1 characterized in that all interior surfaces of said vaneless volute chamber in contact with fluid and including said annular fluid receiving portion and said downstream fluid discharging portion are smooth and free of abrupt changes in contour, and being further characterized in that said long narrow cone and said bell mouth diffuser outlet are substantially circular in crosssection on planes normal to the respective longitudinal axes thereof.

3. A compact centrifugal pressure apparatus as defined in claim 1 characterized in that the axis of said bell mouth outlet is substantially straight and generally tangential to the longitudinal axis of said long narrow volute cone portion at the end thereof adjacent the smaller end of said bell mouth diffuser outlet.

4. A compact centrifugal pressure apparatus as defined in claim 1 characterized in that the longitudinal axes of said long narrow cone and of said bell mouth outlet lie substantially in a common plane inclined slightly to a plane normal to the axis of said rotor.

5. A compact centrifugal pressure apparatus as defined in claim 1 characterized in that the outward flare of said bell mouth diffuser outlet is within the range of 30 and 60 degrees.

References Cited in the file of this patent UNITED STATES PATENTS 870,740 'Mclver et al Nov. 12, 1907 877,191 Hanson Jan. 21, 1908 1,400,322 Sherbondy Dec. 13, 1921 1,662,249 Jennings Mar. 13, 1928 1,845,152 Hutchinson Feb. 16, 1932 1,886,714 Moss Nov. 8, 1932 1,914,919 Heerrnans June 20, 1933 2,433,156 Pezzillo Dec. 23, 1947 2,715,814 Barr Aug. 23, 1955 2,737,897 Dewees Mar. 13, 1956 2,822,974 Mueller Feb. 11, 1958 2,911,138 Birmann Nov. 3, 2,942,556 Growall June 28, 1960 FOREIGN PATENTS 142,883 Sweden Nov. 10, 1953 262,066 Switzerland Sept. 16, 1949 943,938 France Oct. 18, 1948 thereof, said housing

Claims

1. A COMPACT CENTRIFUGAL PRESSURE APPARATUS ADAPTED TO OPERATE EFFICIENTLY OVER A WIDE RANGE OF OPERATING SPEEDS AND A WIDE RANGE OF FLOW RATES, SAID APPARATUS HAVING A HOUSING, A CENTRIFUGAL ROTOR ROTATABLY SUPPORTED IN SAID HOUSING HAVING AN AXIAL FLUID INLET AND AN ANNULAR DISCHARGE FROM THE PERIPHERAL RIM THEREOF, SAID HOUSING HAVING A VANELESS VOLUTE CHAMBER FORMED THEREIN AND OFFSET AXIALLY CLOSELY TO ONE SIDE OF THE RIM OF SAID ROTOR, SAID VANELESS VOLUTE CHAMBER INCLUDING AN ANNULAR FLUID RECEIVING PORTION AND A DOWNSTREAM FLUID DISCHARGING PORTION, SAID ANNULAR FLUID RECEIVING PORTION HAVING A SURFACE ARRANGED TO RECEIVE FLUID FROM SAID ROTOR RIM AND TO DISCHARGE THE SAME AXIALLY OF SAID HOUSING AND TANGENTIALLY INTO SAID DOWNSTREAM DISCHARGE PORTION OF SAID VOLUTE CHAMBER WITHOUT APPRECIABLE ENERGY LOSS, SAID DOWNSTREAM DISCHARGE PORTION SUBSTANTIALLY ENCIRCLING THE AXIS OF SAID ROTOR AND HAVING A LONG NARROW UPSTREAM CONE PORTION TERMINATING AT THE LARGER END THEREOF IN A BELL MOUTH DIFFUSER OUTLET, SAID BELL MOUTH DIFFUSER OUTLET HAVING AN OUTWARD FLARE IN EXCESS OF 30 DEGREES AND EFFECTIVE IN COOPERATION WITH SAID LONG NARROW CONE PORTION TO CONVERT THE HIGH VELOCITY SWIRLING STREAM OF FLUID ADVANCING AXIALLY OF SAID CONE PORTION AND OF SAID BELL MOUTH DIFFUSER OUTLET INTO PRESSURE ENERGY BY THE TIME THE FLUID REACHES THE LARGER END OF SAID BELL MOUTH OUTLET.