US2770891A - Cooled bearings for oven drying machines - Google Patents

Description

Nov. 20, 1956 A. WENDEL coouao BEARINGSFOR OVEN DRYING MACHINES Filed June 28, 1952 Te W E. V mA ATTORNEY United States Patent Lorenz A. Wendel, Somerville, N. J., assignor to The TSinger Manufacturing Company, Elizabeth, N. J., a

corporation of New Jersey I Application June as, 1952, Serial No. 296,117

' ,-1Claim. o1.a4---z1s The present invention relates to means for cooling a bearing of an electric motor, and particularly for that type of motor used for directly driving fans in drying machines, such as disclosed in the prior U. S. Patent No. Re 20,285, dated March 9, 1937.

The electric motor for the fan, which is used to circulate air in the ovenof ,a drying machine, is usually secured outside the casing ofthe oven and the shafts thereof has one end which extends through the easing into the oven. A fan is directly secured to the end of that portion of the sh'aftextending into the oven. In order to provide a space between the casingvand the fan that is adequate for efficient operation ofthe fan, the shaft must be elongated and inorder to provide adequate supportfor the shaft from a standpoint of rigidity; it is necessary to provide a bearing support for the shaft adjacent the end thereof, or as near as possible to the point of connection to the fan. Normally, the shaft is supported in two bearings, one at either end of the outer shell of the motor, and to provide a bearing as near as possible to the fan, the shell is also normally extended within the oven casing.

While the above construction provides an adequate support for the shaft and a satisfactory spacing of the fan and oven casing, it subjects the bearing adjacent the fan to the high temperatures of the oven, which interferes with proper lubrication and consequently destroys the bearing. To overcome this disadvantage, it has been found necessary to provide means for cooling this bearing. Heretofore, this cooling has been provided by a secondary fan, located within the shell of the motor, which circulates air about the bearing. The secondary fan normally is fixed to the motor shaft and also serves as the cooling fan for the motor itself by forcing air about the rotor. While this method has maintained the temperature of the bearing within acceptable limits under-normal operating conditions, it is not adequate under extreme, conditions, and of course, provides no cooling at all when the fan is shut down. These fans are normally employed in groups, and at times, it is desirable to operate only some of them. At those times when it is desired to shut down a fan while holding the oven at its normal temperature, or just while shutting down the system and before the oven has cooled off, the temperature of the bearing would approach that of the oven, which tended to destroy the lubricant and, consequently, the bearing.

It is an object of the present invention to provide an improved means for cooling the bearing of an electric motor which is more efiicient in operation, has a greater cooling capacity, and which will operate independently of the motor.

It is a further object of the present invention to provide an improved means for cooling the bearing of an electric motor which can be readily adapted to existing machines with a minimum of effort.

Having in mind these and other objects that will be evident from an understanding of this disclosure, a presently preferred embodiment of the invention is hereinafter 2 7 set forth in such detail as to enable those skilled in the art to readily understand the function, operation, construction and advantages of it, when read in conjunction with the accompanying drawings in which:

Fig. l is a partial vertical section of an electric motor which includes a preferred embodiment of the present invention.

Fig. 2 is a vertical sectional view taken substantially on the line 2-2 of-Fig. -1.

With reference to the drawings, there is illustrated a portion of an outer shell 1 of an electric motor including stationary field or stator windings 2 and a laminated rotating armature or rotor core 3 having windings 4 die-cast in the slots thereof in th usual manner. The rotoris fixed to a shaft 5 which, as will be readily understood although not illustrated, is journaled at one end in the motor shell 1. The details of the motor will not be described since they do not constitute critical limitations of the invention. However, the motor may be substantially the, same as that illustrated in my prior Patent No. 2,697,179, December 14, 1954, to which reference may be had for furtherdescription thereof.

Secured to the motor shell 1 as by through bolts 6 is an inner end cover 7'which includes a flange 8 apertured to receive bolts8a ,or the like to secure the assembly to an apertured casing 8b of a drying chamber or oven with the motor outside and the end cover portion Within, the oven. An outer cover 9 spaced from the cover 7 is secured to the flange 8 of the cover 7 as by bolts 10. A radial fan 11 for, circulating air through the motor and innercover7 andthrough'the space between the inner and outer covers 7 and 9 is secured to the shaft 5 adjacent the free end thereof for rotation therewith. A fan 11a is secured to the extreme end portion of the shaft 5. The above structure is fully disclosed in my above referred to patent and it is not deemed necessary to expand this disclosure in relation thereto, since reference may be made to that patent for a further description thereof.

The inner cover 7 comprises a support for the shaft 5 in that the shaft 5 is journaled at the end towards the fan in an anti-friction bearing such as a ball bearing 12 fitted in an aperture 13 in an end wall 14 of the cover 7. Fitted about the shaft 5 at the outer end of the aperture 13 is a grease retainer 15. Inner and outer bearing covers 16 and 17, respectively, are fitted over the bearing and are secured to opposite faces of the end wall 14 of the cover 7 by through bolts 18. The grease retainer 15 together with the outer bearing cover 17, and the inner bearing cover 16 serve to close the respective ends of the aperture 13 and thus define a lubricant chamber 19 in which the bearing 12 is fitted. Lubricant in the form of grease may be packed in the lubricant chamber 19 at the initial assembly, or may be supplied to the lubricant chamber 19 through a duct terminating outside the motor shell 1 and covers 7 and 9 on the motor side of the flange 8 in a conventional pressure fitting as illustrated in my above mentioned application. A grease drain duct may also be provided if desired.

The inner bearing cover 16 is preferably cast in bronze, although it could obviously be built up from sheet material, and is provided with an integral jacket or coolant chamber 24 through which a cooling medium is adapted to be circulated. The cover 16 is also provided with a machined surface 25 that is seated against a similarly machined surface on the end wall 14 about the aperture 13. This surface 25 not only confines the lubricant within the compartment 19 but also constitutes a heat transfer surface through which heat is conducted away from the bearing 12 to the coolant chamber 24. As will be understood, the larger and the more accurate the surface 25 and the corresponding surface on the wall 14 is made the better will be the heat conductivity towards the coolant chamber 24.

The cooling medium, preferably water, enters the jacket 24 through an aperture 26 from a conduit 27 which extends externally of the motor and-Which is connected to a conduit 28 that supplies the coolant under pressure through a releasable tube union 29 of conventional design. There are provided four of the apertures 26, spaced angularly at ninety degrees about the periphery of the-jacket and having angularly adjacent ones thereof comprising pairs which are arranged in spaced planes normal to the axis of the jacket. It will be understood that the coolant will always enter one of the apertures of one ofsaid pairs and leave through an aperture in the other of said pairs. The particular apertures selected depend upon whether the motor is to be used with the longitudinal axis thereof arranged vertically or horizontally, having in mind that the coolant should always enter the jacket from a low point and exit at a vertically higher point to prevent air lock. The unused apertures 26, which facilitate molding, are, of course, plugged as at 30. The cooling medium leaves the jacket 24 through a conduit 31 also communicating with an aperture 26 and which also extends externally of the motor and is connected to a waste conduit 32 through a connection 33 similar to the connection 29.

From the above, it will be noted that there has been provided a cooling system for the bearing which is of suflicient capacity to maintain the hearing at an acceptable temperature during any normal operation, and which will operate independently of the operation of the motor to prevent overheating of the bearing while the motor is shut down. It will also be seen that there has been provided a cooling means which can readily be adapted for use with many existing motors since it involves only supplying an inner bearing cover provided with a jacket as disclosed.

Having thus set forth the nature of the invention, wha I claim herein is: t

In a fan for circulating air within an oven of a drying machine having a casing provided with an aperture, a member for surrounding the aperture and for extending into the oven, an anti-friction bearing carried by said member and being spaced from and axially alined with said aperture, a driven shaft extending through said aperture and journaled in said bearing, a fan fixed to the free end of said shaft within saidoven, means for confining lubricant about said bearing comprising bearing covers surrounding said shaft upon opposite sides of saidbearing and being secured to opposite faces of said member about said bearing, one of said bearing covers being provided with a coolant chamber having two pairs of diametrically opposed apertures formed therein, and conduits for conducting coolant to and from said jacket through said apertures, one aperture of each of said pairs being arranged in each of two spaced planes normal to the axis of said bearing cover, whereby the coolant may enter said jacket from a low point and exit therefrom at a vertically higher point when said shaft is arranged vertically and when arranged horizontally.

References Cited in the file of this patent UNITED STATES PATENTS 394,056 Cameron Dec. 4, 1888 418,123 Grimm Dec. 24, 1889 2,050,180 HurXthal Aug. 4, 1936 2,142,931 Baker Jan. 3, 1939 2,169,331 Wechsberg Aug. 15, 1939 2,196,952 Bogaty Apr. 6, 1940

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