US2717732A - Hot fan - Google Patents

Description

Sept. 13, 1955 w. H. DAILEY, JR

HOT FAN Filed Dec. 8, 1949 INVENTOR.

lM/i Daf/g/Jn United States Patent nor FAN William H. Bailey, Jr., near Library, Pa., assignor to Surface Combustion Corporation, Toledo, Ohio, a corporation of Ohio Application December 8, 1349, Serial No. 131,828 9 Claims. (Cl. 230-209) The present invention relates to fans for circulating a hot atmosphere in a furnace chamber. In fans of this type the impeller is in the furnace chamber and the bearings and drive mechanism are outside thereof. However, there is a tendency for the bearing nearest the fan to overheat and therefore cooling means must be employed to prevent this overheating. There are also problems involving maintaining the hearings in alinement and lubrication of the bearings and air leakage through the fan assembly. The present invention aims to provide a practical solution to these various problems.

For a consideration of what I consider to be novel and my invention, attention is directed to the following specification and the claims appended thereto.

In the accompanying drawing,

Fig. 1 shows the improved fan applied to a furnace of the type commonly employed for the annealing of a stack of coils of sheet metal.

Fig. 2, except for the omission of an intermediate portion of the assembly and except for the omission of the impeller together with a portion of the stub shaft on which the latter is mounted, is a combined axail section and elevation of the improved fan.

Pig. 3 is a fragmentary section on line 3--3 of Fig. 2.

Fig. 4 is a fragmentary section on line 4-4 of Fig. 2.

The furnace shown in Fig. 1 comprises a base 10, an annular stool 11 on the base for supporting a tubular stack 12 of coils of sheet metal to be annealed, an inner protective cover 13 about the coil stack, and a portable heating head 14 about the inner cover. The improved fan is generally indicated at 15 and comprises an impeller 16 arranged below the top side of stool 11 coaxial therewith for circulating the atmosphere within the inner cover T3. The drive shaft for the impeller is indicated at 17, the same extending through a supporting barrel 20 and having a drive pulley 21 at its lower end. The barrel is secured to the furnace base 10 by a supporting flange 22.

The upper end of the barrel 20 is closed by ring member 23 mounted thereon with running clearance between the shaft 17 and the ring. Secured to the shaft 17 as by a radial pin 24 is a dust cap 25 above the ring member 23. The lower end of the barrel 20 is closed by a ring member 26 the bore of which is sufliciently large to accommodate oil seal means generally indicated at 27 about the shaft 17.

The downthrust of the drive shaft 17 is taken by a ball bearing 30, the bearing comprising an inner race 31 and an outer race 32. On the drive shaft below the inner race is a clamping nut 33 between which and the race 31 an oil slinger 34 may be clamped. An upstanding circular wall 35 tends to isolate the oil seal means 27 at the lower end of the shaft from the oil from said slinger. The outlet for the oil from the slinger is an adjacent aperture 36 in the side wall of the barrel 20.

The outer race 32 is secured to the lower end of a tall sleeve 37 which a short distance above its lower end is secured to said barrel by a press fit indicated by the joint 38. There is a clearance space 39 between said barrel and the lower end of said sleeve below said joint 38 and there is a clearance space 40' between said barrel and the entire upper portion of the sleeve 37. The function of these clearance spaces 39 and 40 will presently appear. A circular row of upstanding fingers 41 on the upper side of the closure ring 26 at the lower end of the barrel 2% abuts the underside of the lower race 32 so that downward thrust or displacement of said race 32 is transmitted to said ring 26 rather than to the sleeve 37. The fingers 41 are preferably also wide enough to underlie and abut the lower end of said sleeve 37. Oil which drains through the bearing 30 from above is removed from below the bearing through the adjacent oil outlet 36, it being understood that a waste oil tube not shown conducts the oil away from said outlet 36.

The upper shaft bearing is indicated at 43 and comprises an inner race 44 and an outer race 45. On. the shaft above the inner race 44 is a sleeve 46 the lower end of which abuts the top side of the race to hold it down, the sleeve preferably being long enough to extend above the top of the closure ring 23 for securement to the shaft 17 by the radial pin 24 which holds the dust cap 25 in place. The outer race is secured to the upper end of the tall sleeve 37 and a depending rim 48 on the ring member 23 overlies the outer race in spaced but relatively close relation.

To permit drainage of excess lubricating oil from above to below the upper bearing 43 there is provided in the inner face of the sleeve 37 where the outer race 45 contacts the same, a series of vertical by-pass grooves 49. To permit drainage of excess oil from above to below the lower bearing 30 to the oil outlet 36 in the barrel 2%) there is provided a by-pass around the bearing. This by-pass consists of the clearance space 39 between the lower end of the liner sleeve 37 and communicating radial holes 51 in said sleeve next above the outer race 32. Oil is delivered to the space above the upper bearing 43 from an oil inlet 52 in the side wall of the barrel 20 through conduit means consisting of the clearance space 40 between the barrel 2t and the sleeve 37 and communicating radial holes 53 in the lower portion of the closure ring 23 at the top of the barrel 20.

The primary advantage resulting from providing the 1 tall sleeve 37 within the barrel 20 is that the alinement of the upper and lower bearings 43 and 30- with respect to each other is not seriously disturbed by mounting stresses applied to the barrel by the mounting flange 22.

Since the upper end of the drive shaft 17 operates in a furnace chamber, the upper bearing 43 tends (in the absence of cooling means), to become overheated by heat conducted thereto from the highly heated upper portion of said shaft and it is one of the objects of the present invention to provide improvements in means for maintaining said upper bearing relatively cool. The upper portion of the shaft 17 whereon the impeller 16 is mounted is a stub shaft 54 whose lower end extends into the upper end of a tubular portion 55- of the shaft 17 with a press fit as indicated by the joint line 56, the said tubular portion being that portion of the drive shaft which is supported by the upper and lower bearings 43 and 30. As indicated. at 58, the lower portion of the stub shaft 54 is hollow for a reason presently appearing.

In order to reduce the transfer of heat from the hot end of the drive shaft to the upper bearing 43 to a minimum, heat is conducted from the stub shaft 54 in advance of the upper bearing to a point. below the. latter by an elongate heat conducting core or body 57 having high heat-conducting properties such as copper, silver and aluminum, copper being preferred. At its upper end 60, the core 57 makes a press fit with the lower end of the stub shaft54 and next therebel'ow, as indicated at 61, is enlarged for a portion of its length to make a press fit with the tubular portion 55 of the shaft 17. At its lower end, the core 57 is again enlarged, as indicated at 62, to make a press fit the lower end of said shaft portion 55. Heat absorbed by the upper end of the core 57 is therefore conducted to the lower end of the shaft 17 where it is dissipated by the pulley 21. Between its enlarged portions 61 and 62, the core 57 is reduced enough to provide a substantial clearance space 63 between itself and the tubular shaft portion 55. It will be appreciated that the core body 57, being of copper (or silver or aluminum) is incapable of transmitting the driving stresses which the steel shaft 17 is designed to transmit at furnace temperature conditions. Being pressed into position, it maintains excellent heat transferring contact without transmitting load, and it serves to maintain the entire region about the bearing 43 relatively cool.

The present invention also provides a relatively simple system for reducing to a minimum the infiltration of air into the annealing chamber of the fan assembly. To this end the closure 26 at the lower end of the barrel 20 is provided with inlet 64 for purging gas from a suitable source of supply which may be the same as that which supplies protective gas to the space within the inner cover 13 of the annealing furnace. An aperture 65 in the side wall of the tubular portion 55 of the fan shaft 17 permits the purge gas from said inlet 64 to enter the clearance space 63 between said tubular portion 55 and the heat conducting core 57. A communicating gas passage 66 through the upper end of the core 57 permits the gas to flow from the clearance space 63 to the hollow portion 58 of the stub shaft 54. A radial aperture 67 in the side wall of the stub shaft 54 permits the purge gas to flow from the hollow position 58 to a circumferential groove 70 in the bore of the closure 23 at the top of the barrel 20. The clearance space between said closure and the drive shaft 17 permits the main stream of purge gas in the groove 70 to divide with a portion flowing upward and finally into the furnace chamber and another portion flowing downward for final exit through the oil outlet 36 along with the outgoing oil, thereby purging the assembly of air and preventing its entrance thereinto.

From the foregoing description it is apparent that the present invention provides a fan assembly that is well adapted for its intended use.

What is claimed as new is:

1. In combination, a drive shaft of which one end operates in a heated and the other end in a relatively cool environment; a first bearing at the hot end of the shaft; a second hearing at the cold end of the shaft; the shaft from its cold end to beyond said first bearing comprising a tubular portion; a body of heat conducting metal within the tubular portion of the shaft and extending from the cold end of the latter to the region of the first bearing for abstracting heat from the hot end of the shaft and thence conducting it toward the cold end of the shaft; means on the cold end of the shaft for dissipating the heat conducted thereto by said heat conducting body; the second bearing being intermediate the first bearing and the means on the cold end of the shaft for dissipating heat; a tubular member wherein said bearings are housed; support means comprising said tubular member for supporting said shaft, and comprising a barrel wherein the tubular member is housed and by which it is supported against axial displacement; said tubular member and said barrel forming an oil sealing joint between said first and second bearings, and oil passages above and below said joint; means comprising the oil passage above said joint for supplying oil to the hot end of said first bearing; means comprising a passage in said tubular member for draining excess oil from the hot end of said first bearing to a passage to the second bearing formed between said tubular mem- (iii ber and said shaft and to the second bearing; and means comprising the oil passage below said joint for draining excess oil from above the second bearing.

2. In combination, a drive shaft of which one end operates in a heated and the other in a relatively cool environment; first and second bearings, respectively, supporting the shaft near its hot and cold ends; the shaft comprising a tubular, torque transmitting portion of relatively low heat conductivity from its cold end to beyond the first bearing; a body of high heat conductivity within the tubular portion of the shaft and extending from the cold end of the latter to the region of the first bearing, and in heat conducting relation with the shaft in the region of the first bearing and at the cold end of the shaft; and means on the cold end of the shaft for dissipating heat conducted thereto by said body.

3. In combination, a drive shaft of which one end operates in a controlled atmosphere chamber and the other is exposed to atmospheric air; a tubular member within which the shaft operates and forming with the shaft a bearing chamber, the atmosphere chamber end of which communicates with the inside of the atmosphere chamber and the other end of which communicates with atmospheric air; bearing means in the bearing chamber supporting the shaft in its operating position; and gas seals at the ends of the bearing chamber; the shaft forming a sealed gas passage from the bearing chamber between the bearing means and one seal to the bearing chamber between the bearing means and the other seal; and the tubular member forming a purge gas inlet to the bearing chamber between the bearing means and one of the gas seals.

4. In a furnace having heating means and a fan for circulating atmosphere in the furnace, in combination, a drive shaft for turning the fan, the fan end of which operates in a heated and the drive end in a relatively cool environment; a tubular member within which the shaft operates and forming with the shaft a bearing chamber; spaced fan and drive end hearings in the bearing chamber supporting the shaft in the member; gas seals at the fan and drive ends of the bearing chamber; the tubular member forming oil inlet and outlet passages to the bearing chamber between the bearings and gas seals at the respective ends of the bearing chamher, and by-pass oil passages around the respective hearings to the portion of the bearing chamber between the bearings; the drive shaft comprising a hollow portion from its drive end to the fan side of the fan end bearing; and a relatively highly heat conductive metal body disposed in the hollow portion, sealing said portion from ingress of atmospheric air, extending to and in heat conducting relation with the shaft in the region of the fan end bearing; said shaft and body forming in the shaft a passage for purge gas from the bearing chamber between the fan end bearing and its adjacent gas seal to the bearing chamber between the drive end bearing and its adjacent gas seal; and the tubular member forming an inlet for purge gas to the bearing chamber between a bearing and a gas seal.

5. In combination; a hollow rotatable shaft for transmitting torque; means engaging said shaft to provide a hearing within which said shaft is journaled, said shaft projecting beyond both ends of the region of engagement of said bearing means with said shaft; and a member disposed within said shaft, said member having a good heat conducting connection with said shaft at spaced points along said shaft beyond each of the two ends of said region of bearing engagement and being out of contact with said shaft along said region and said member having a substantially higher heat conductivity between its said points of connection with said shaft than the portion of said shaft between said points.

6. In combination; a rotatable shaft for transmitting torque; means engaging said shaft to provide a bearing therefor, said shaft projecting beyond both ends of the region of engagement of said bearing means with said shaft; and a member having a good heat conducting connection with said shaft at spaced points along said shaft beyond each of the two ends of said region of bearing engagement and being out of contact with said shaft along said region, said member having a higher heat conductivity between its said points of connection with said shaft than the portion of said shaft between said points.

7. In combination; a rotatable shaft for transmitting torque, said shaft being hollow whereby said shaft has an annular inner and an annular outer surface; means engaging one of said shaft surfaces to provide a hearing for said shaft, said shaft projecting beyond both ends of the region of engagement of said bearing means with said shaft; and a member having a good heat conducting connection with said other shaft surface at spaced points along said shaft beyond each of the two ends of said region of bearing engagement and being out of contact with said shaft along said region, said member having a higher heat conductivity between its said points of connection with said shaft than the portion of said shaft between said points.

8. In combination; a hollow rotatable shaft for transmitting torque, one end of said shaft being exposed to relatively high temperatures during operation of said shaft as compared to the temperatures at the other end of said shaft; means engaging said shaft adjacent to its high temperature end to provide a bearing within which said shaft is journaled, said shaft projecting beyond both ends of the region of engagement of said bearing means within said shaft; anda member disposed within said shaft and having a good heat conducting connection with said shaft at spaced points along said shaft the two ends of said region of bearing being out of contact with said shaft said member having a substantially higher heat conductivity between its said points of connection with said shaft than the portion of said shaft between said points and said shaft having a co-efficient of heat conductivity of the order of magnitude of steel and said member having a co-efficient of heat conductivity of at least the order of magnitude of aluminum.

9. In combination; a hollow rotatable shaft for transmitting torque, one end of said shaft being exposed to relatively high temperatures during operation of said shaft; means engaging said shaft to provide a bearing within which said shaft is journaled, said shaft projecting beyond both ends of the region of engagement of said bearing means with said shaft; and a member disposed within said shaft, said member having a good heat conducting connection with said shaft at spaced points along said shaft beyond each of the two ends of said region of bearing engagement and being out of contact with said shaft along said region and said member having a substantially higher heat conductivity between its said points of connection with said shaft than the portion of said shaft between said points.

beyond each of engagement and along said region,

References Cited in the file of this patent UNITED STATES PATENTS 1,991,623 Onsrud Feb. 19, 1935 2,012,579 Obayashi Aug. 27, 1935 2,202,424 Hough May 28, 1940 2,397,012 Jepson Mar. 19, 1946 2,439,127 Dailey Apr. 6, 1948 2,659,530 Garnier Nov. 17, 1953

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