US 3089637 A
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May 14, 1963 A. H. BELL AIR CIRCULATING SYSTEM AND BLOWER STRUCTURE 2 Sheets-Sheet 1 Filed May 2, 1960 May 14, 1963 Filed May 2, 1960 A. H. BELL 3,089,637
AIR CIRCUQATING SYSTEM AND BLOWER STRUCTURE 2 Sheets-Sheet 2 IN VEN TOR.
United States Patent Office 3561891537 Patented May 14, 1963 3,089,637 AIR CmCULATING SYSTEM AND BLOWER STRUCTURE Albert H. Bell, Birmingham, Micln, assignor to Chrysler Corporation, Highland Park, Mich, a corporation of Delaware Filed May 2 1960, Ser. No. 25,929 1 Claim. (Cl. 230-117) This invention relates to an air circulating system utilizing an improved axial flow blower for increasing the pressure of the air therein, which system is particularly adapted for use in vehicle installations requiring high circulating volumes for a minimum blower size.
Heretofore, squirrel cage or centrifugal type blowers of the general type shown in Patent No. 2,231,063 have been used in automotive air circulating systems, but due to the inherent nature of the air flow therein and the necessity for the volute scroll for collecting the air, these blowers must be of relatively large size insofar as outside dimensions are concerned. Moreover, the motors must be relatively large on centrifugal blowers because of their lower efiiciencies and the less effective cooling of the motor for the pressure and flow delivery equivalent to that of axial blowers.
This invention eliminates many of these problems by using an improved axial type blower in the duct work of the air circulating system. The higher efiiciency of the axial blower results in a reduction in battery drain, and thus an effective unloading of the electrical system of the car. Because of its small size and straight-through flow feature, the axial flow blower offers greater flexibility of installation. Moreover, a right angle bend in the duct work at the point of blower installation is no longer required and the blower can be placed into the duct work at any point where a reasonably uniform inlet velocity exists.
The axial blower is compact in size since no collector scroll is required and higher rotational speeds are employed. Higher blower efficiencies are realized, reducing power consumption 25% to 30% over conventional installations of other type blowers having the same delivery requirements. Considerably smaller motors are used in the axial blowers, and this, in part, is made particularly feasible due to better motor cooling obtained by applicant in positioning the blower motor in the air stream. The following chart shows a comparison of applicants improved axial flow blower and the standard centrifugal blower:
Axial flow blower Standard centrifugal blow or 150 c.f.m. at .8 water static pressure.
Delivery requirements at design point.
Nominal mounting 150 0.11m. at .8 water static pressure.
space required. (without inlet). (without inlet). Motor size 3 dia. x staek. 3 dia. x 2 stack. Power consumption 73.9 watts 100.8 watts.
at design point. Blower rpm 4,28 2,010. Motor temperature 76 F 123.5 F.
rise for all of the above conditions.
shown by the fact that if the above axial blower motor were used with a centrifugal blower the motor would reach its limiting temperature rise of approximately 123 F. with only 40 watts input. The temperature rise power input relationship is in such a case greater than 3 F./watt, while the combination of the same motor with an axial blower would give approximately only 1 F./watt.
A feature of the present invention which allows the use of smaller blower motors is the provision of a bullet or tapered shaped motor housing which allows high static air pressure to be developed at the exit end of the blower. Aperture means is provided in the housing to allow this high pressure to force air into the inside of the housing and to 'circulate about through the motor end plates and the motor therein. This air is then drawn out through the gap between the blower rotor and motor housing to thereby re-enter the main air stream.
A principal object of this invention is to provide a novel cooling means for axial flow blowers so that the size thereof can be reduced and the power increased without causing excessive heating of the motor.
A further object is to provide the aforementioned novel features of axial flow blowers in automotive air circulating systems.
Further objects and advantages of the present invention will become apparent from the following description of the drawings, in which:
FIGURE 1 represents a portion of the duct work of a vehicle air circulating system utilizing an axial flow blower;
FIGURE 2 represents a cross-sectional view of the blower of FIGURE 1 taken along the line 22 thereof in the direction of the arrows;
FIGURE 3 represents a partly broken away view of the axial flow blower of FIGURE 1; and
FIGURE 4 represents a longitudinal cross-sectional view of the axial flow blower of FIGURES l to 3.
Referring to FIGURE 1 of the drawing, a duct work generally designated 10 is provided with an inlet portion 12, an outlet portion 14, and an axial flow blower 16. inlet 12 and outlet 14 may be positioned to communicate with any portions of the structure in which the blower 16 is to move air. [For example, inlet 12 may be in com munication with the car heater coil while outlet 14 may be opened to the passenger compartment through a movable 'vent door 13.
Blower 16 is provided with a shroud 18 mounted on rubber cushions 17 in the duct 10 and having a bellshaped mouth 19 for enhancing the air ilow thereinto. The shroud 18 may be integrally formed by a 'die casting operation with the stator blades or turning vanes 20 and motor housing 22.
The blower rotor 24 having blades 26 is mounted on a shaft 28 of an electric motor 30, the stator 31 of which is secured in the housing 22 by suitable bolts 32 and nuts 29. Threaded anchor nuts 25 imbedded into housing 22 receive bolts 32, and nuts 23 lock them and spaced legs 21 of motor support plate 35 in place on spaced shoulders 39. Front motor support plate 37 against which nuts 29 bear is formed into a cup-shape having peripherally spaced legs 27 which are forced against the end of the motor stator stack to compress it against the shoulder 15 of housing 22. Motor rotor 33 is mounted in bearing means 34 and 36 secured in the end Plates 35 and 37 respectively.
The motor housing 22 is provided with a bullet-shaped exit end 38 for diffusing the high velocity air and increasing the static pressure thereof. An aperture 40 is provided in end 38 through which the high pressure air in the vicinity of the exit end 42 of the blower shroud may be drawn toward the low pressure area intermediate the blower rotor and blower stator. This air is drawn into the housing 22 to circulate throughout the motor 30 between its rotor and stator and also through apertures in the rotor and stator should such apertures be provided, and is finally expelled through suitable openings such as gap 44 at the rear of the rotor within the low static pressure area of the blower. The cooling efiiect of this air flow is quite significant and as stated above, a smaller motor can be used with a higher power input.
An axial flow blower comprising a tubular shroud provided with an air inlet and an air outlet, a housing supported within said shroud and presenting a tubular portion having a substantially imperforate end portion adjacent said air outlet in spaced co-axial relationship with said shroud, said housing having leading and trailing portions and said housing and said shroud cooperating to define an air passage having a portion between the above-mentioned inlet and outlet in which the cross sectional area of that portion of the passage increases, a plurality of stationary vanes extending outwardly between said housing and said shroud intermediate said leading and trailing portions to define generally longitudinally extending air passages therebetween, electric motor means supported within said substantially imperforate tubular housing, said electric motor means having air passageways extending therethrough for cooling of such motor and said motor being provided with a driven shaft extending axially of said housing, a rotor positioned upstream of said housing leading portion and provided With vanes, said rotor being operatively connected to said shaft for rotation therewith, means forming a first opening in the substantially imperforate end portion of said housing and substantially aligned with the axis of said housing, the above-mentioned first opening communicating with a region of maximum cross sectional area of the above-mentioned air passage portion for the admission of air to said housing and means forming a second opening in said housing ahead of said electric motor means in a region of minimum cross sectional area of the abovementioned pass-age portion to accommodate the discharge of air from said housing ahead of said electric motor means whereby a principal air flow is induced by said rotor from the above-mentioned shroud inlet to the shroud outlet and through the space between said housing and said shroud with a higher static pressure in the vicinity of said housing trailing portion than in the vicinity of said rotor and a flow of air induced by such static pressure differential occurs within said housing between the-above-mentioned first and second openings and through said motor air passageways to cool said electric motor means.
References Cited in the file of this patent UNITED STATES PATENTS 1,605,586 Hoover Nov. 2, 1926 1,932,231 Schmidt Oct. 24, 1933 2,397,171 Troller ct a1. Mar. 26, 1946 2,592,471 Sawyer Apr. 8, 1952 2,709,035 Schmidt May 24, 1955 2,867,238 Wilfert Jan. 6, 1959