KEMP JACK AUSTIN (US)
| GB1583822A | 1981-02-04 | |||
| US3782796A | 1974-01-01 | |||
| US2811378A | 1957-10-29 | |||
| US4483430A | 1984-11-20 | |||
| DE2628828A1 | 1977-12-15 | |||
| US2890687A | 1959-06-16 | |||
| US3708215A | 1973-01-02 | |||
| US4148271A | 1979-04-10 |
| 1. | Fan drive mechanism (10) comprising a spindle (12) having an axis, a fan plate (15) for mounting a fan on said spindle (12), drive means (28, 30, 34, 48, 56, 60) for rotating said fan plate (15), bearing means (18, 20) for rotatably mounting said fan plate (15) on said spindle (12), said bearing means (18, 20) including an inner race (24) mounted on said spindle (12), an outer race (22) mounted on said fan plate (15), and rotary force transmitting means (26) for providing a rotary force transmitting connection between said races (22, 24), and stop means (64) for retaining said bearing means (18) on said spindle (12), characterized in that said stop means (64) has a surface (70) tapering radially outwardly with respect to said axis of the spindle (12) to define a conical surface for engagement by said rotary force transmitting means (26) upon separation of the latter from said inner race (24) to thereby limit the axial displacement of the fan plate (15) with respect to . said spindle (12) upon failure of the bearing means (18', 20) . |
| 2. | Fan drive mechanism as claimed in claim 1, further characterized in that said force transmitting means (26) are ball bearings. |
| 3. | Fan drive mechanism as claimed in claim 1, further characterized in that said stop means (64) is a nut threadedly mounted on said spindle (12). |
| 4. | Fan drive mechanism as claimed in claim 3, further characterized in that said nut (64) has a forward face (66) for engagement with said inner race (24) and said conical surface (70) tapers from said forward face (64) toward the end of said spindle (12) when said nut (64) is installed thereon. |
| 5. | Fan drive mechanism as claimed in claim 1, further characterized in that said drive means (28, 30,34 48, 56, 60) includes a driving member (28, 34) rotatably mounted on said spindle (12), said driving member (28, 34) including a portion (34) movable axially along said spindle (12) for driving engagement with said fan plate (15) to form a driving connection between said driving member (28, 34) and said fan plate (15), said portion (34) moving away from said fan plate (15) to 5 break said driving connection, and fluid pressure responsive means (48, 56) for moving said portion (34) along said spindle (12), the axial length of said conical surface (70) along the axis of said spindle (12) being sufficiently long to permit movement of said fan plate 10 (15) after failure of said bearing means (18, 20) a distance at least incrementally longer than the maximum axial movement of said portion (34) on said spindle (12). |
| 6. | Fan drive mechanism as claimed in claim 5, further characterized in that said fluid pressure '5 responsive means (48, 56) includes a cylinder assembly (48) mounted on said spindle (12) slidably receiving a fluid pressure responsive piston assembly (56) , said piston assembly (56) being slidably mounted on said spindle (12), and means (26) for communicating fluid 0 pressure into said cylinder assembly (48). |
| 7. | Fan drive mechanism as claimed in claim 6, further characterized in that said cylinder assembly (48) includes a portion (50) engaging said inner race (24). |
| 8. | Fan drive mechanism as claimed in claim 1, 5 further characterized in that said drive means (28, 30,34 48, 56, 60) includes a disengageable means (28, 34) rotatably mounted on said spindle (12) and including means (34) engageable and disengageable from said fan plate (15) for effecting and breaking a driving 30 connection between said drive means (28, 34) and said fan plate (15), said drive means (28, 30, 34, 48, 56, 60) including a fluid pressure responsive piston (56) slidably mounted on said spindle (12) for effecting engagement and disengagement of said drive means (28, 30, 35 34, 48, 56, 60), the axial length of said conical surface (70) along the axis of said spindle (12) being sufficiently long to permit movement of said fan plate (15) after failure of said bearing means (18, 20) a distance at least incrementally longer than the maximum stroke of said piston (56). |
| 9. | Fan drive mechanism as claimed in claim 8, further characterized in that one end of said conical 5 surface (70) terminates in a flange (72) projecting radially with respect to said spindle (12) to cooperate with a portion (74) of said fan plate (15) extending axially along said spindle (12) to protect said bearing means (18, 20) from environmental contaminants. |
| 10. | 10. Fan drive means as claimed in claim 9, further characterized in that the other end of said conical surface terminates in a forward face (66) for engagement with said bearing race (24). |
| 11. | Fan drive mechanism as claimed in claim 4, '5 further characterized in that said conical surface (70) tapers from said forward face (66) to a flange (72) projecting radially with respect to said spindle (12) to cooperate with a portion (74) of said fan plate (15) extending axially along said spindle (12) to protect said' 0 bearing means from environmental, contaminants. |
This invention relates to a fan drive mechanism for operating the cooling fan of a vehicle engine. Background of the Invention
Fan drive mechanisms for operating the cooling fan of a vehicle engine have been proposed before; for example, such a fan drive is disclosed in U.S. Patent 4,483,430 issued Nov¬ ember 20, 1984 to Carmichael et al. The present invention prevents damage to the radiator and to other vehicle compon¬ ents in case of premature failure of the fan drive mechanism. Exisiting fan drive mechanisms mount a rotating fan plate adjacent the vehicle radiator. A clutching mechanism in¬ cludes springs which urge a pressure plate into driving engagement with the fan plate when the clutch is engaged.
When the bearings supporting the fan plate fail, the springs force the fan plate, which continues to rotate, into the vehicle radiator, causing damage to both the fan and the radiator. The vehicle operator has no warning of this con- dition until the engine overheats due to loss of radiator coolant. Accordingly, what is initially a relatively inex¬ pensive repair of the fan drive mechanism turns into an expensive major repair of the fan drive, fan and radiator. Furthermore, automatic shutdown systems to prevent engine overheating prevent the vehicle from being moved with a damaged radiator, but if the fan drive mechanism alone fails, the vehicle may be moved a short distance by depending upon ram air cooling. Summary of the Invention The present invention captures the fan plate in case of bearing failure and retains it on its supporting spindle while stopping rotation of the fan plate. Accordingly, the driver is warned of the failed fan drive upon overheating of the radiator and the resulting indication to the vehicle operator. Damage to the fan and the radiator is thereby prevented. Description of the Drawing
These and other advantages of the invention will
be apparent from the following detailed description, with reference to the accompanying drawing, the sole figure of which is a partial longitudinal cross sectional view of a fan dri've mechanism made pursuant to the teachings of the present invention. Detailed Description
Referring now to the drawing, a fan drive mechanism generally indicated by the numeral 10 includes a spindle 12 which is mounted to a stationary portion of the vehicle by a bracket 14. The spindle 12 is generally mounted in front of the vehicle engine and between the engine and the vehicle radiator so that operation of the cooling fan draws air through the radiator in the conventional manner. The engine cooling fan (not shown) is bolted to a fan plate 15 by bolts received in openings 16 in the fan plate 15. The fan plate 15 is mounted on the spindle 12 by bearings 18, 20. Each of the bearings 18, 20 includes an outer race 22 which is fixed to the fan plate 15, an inner race 24, which is mounted on the. spindle 12, and ball bearings 26 interposed between the races 22, 24.
A driving member generally indicated by the numeral 28 is rotatably mounted on the spindle 12 by bearings generally indicated by the numeral 30. The driving member 28 is pro¬ vided with the conventional V-belt grooves 32 for connection with the vehicle engine so that the driving member 28 may be rotated thereby. The driving member 28 further includes a pressure plate generally indicated by the numeral 34 which is supported on circumferentially spaced pins 36 on the portion 38 of the driving member 28 which carries the V-belt grooves 32. The pressure plate 34 carries friction material 40 for engagement with the conical engagement surface 42 defined on the fan plate 15 to thereby form a driving connection between the driving member 28 and the fan plate 15 when the drive mechanism effects a driving connection with the vehicle fan. Circumferentially spaced springs 44 between the portion 38 of the driving member 28 and the pressure plate 34 yieldably urge the pressure plate 34 into driving engagement with the fan plate 15. However, when a sensor (not shown) senses that the cooling effect of the fan is not necessary, the
driving connection with the fan plate 15 is broken by moving the pressure plate 34 out of driving engagement with the engagement surface 42 by operation of a fluid motor generally indicated by the numeral 46. 5 Fluid motor 46 includes a circumferentially extending cylinder assembly generally indicated by the numeral 48. Cylinder assembly 48 is mounted on the spindle 12 and includes a face 50 which is engaged by the inner race 24 of the bearing 18 and an opposite face 52
10 which is engaged by a shoulder 54 on the spindle 12, thereby locking the cylinder assembly 48 on the spindle 12. A piston assembly 56 is slidably mounted on larger diameter portion 58 of the spindle 12 and is slidingly received within the cylinder assembly 48. The pressure
15 plate 34 is rotatably supported on the piston 56 by a bearing generally indicated by the numeral 60.
The spindle 12 terminates in a threaded end 62. A stop nut generally indicated by the numeral 64 is threadedly received on the threaded end 62 and ' includes a . • 20 circumferentially extending forward face 66 which abuts the inner race 24 of the bearing 20. The nut 64 is retained by a cotter pin 68 received through an opening in nut 64 and hole in shaft 12 end. A conical surface generally indicated by the numeral 70 tapers radially
25 outwardly from the face 66. The conical surface 70 terminates in a radially projecting flange 72 that cooperates with axially extending portion 74 of fan plate 15 to at least partially protect the bearings 18, 20 from environmental contaminants.
30 in operation, springs 44 normally yieldably urge the pressure plate 34 into driving engagement with the fan plate 15 so that rotation of the driven member 28 by the vehicle engine is transmitted to the fan plate 15 to thereby rotate the engine cooling fan. When the
35 aforementioned sensor senses that the cooling effect of the fan is no longer necessary, the sensor communicates air pressure from the vehicle air brake system through the passages 76 within the spindle 12 into the chamber
defined between the cylinder 48 and the piston 56. Fluid pressure in the chamber urges the piston 56 to the left, viewing the Figure, thereby urging pressure plate 34 away from driving engagement with the fan plate 15, to break the driving connection therebetween to permit the fan plate 15 to freewheel on the bearings 18, 20, until the aforementioned pressure sensor senses that the cooling effect of the fan is again necessary, whereupon the chamber between the piston 56 and cylinder assembly 48 is vented to permit the springs 44 to again urge the pressure plate 34 into driving engagement with the fan plate 15.
The bearings 18, 20 which rotatably support the fan plate 15 may ultimately fail. When this occurs, springs 44 tend to drive the pressure plate 34 and fan plate 15 to the right, viewing the Figure. In prior art devices, the fan plate 15 was driven off the end of the spindle 12, while the fan plate 15 continued to rotate. However, instead of the fan plate 15 being free to move off the end of the spindle 12 and engage the radiator, the conical surface 70 catches the balls 26 and outer race 22 of the bearing 20. The conical surface 70 tapers such that the force transmitting balls of the bearing 22 are caught at some point on the axial length of the conical surface 70. As the bearing parts jam into the conical surface 70, the conical surface 70 frictionally engages the bearing parts to stop the fan plate 15 from rotating, while the tapered surface 70 controls the wobble of the plate 15 as it comes to the stop, thereby preventing it from deflecting into the radiator.
It should be noted that the axial length of the surface 70 is sufficiently long that it limits movement of the plate 15 along the axis of the spindle 12 during failure of the bearings to an incremental amount longer than the maximum stroke of the piston 56. The maximum stroke of the piston 56, of course, is also the maximum axial movement of the pressure plate 34. Accordingly, because an incremental additional axial movement of the
plate 15 is permitted upon failure of the bearings, it, can be assured that the plate 15 will be permitted to move out of driving engagement with the pressure plate 34. Accordingly, the breaking effect of the friction between the conical surface 70 and the bearing parts is able to stop rotation of the fan plate 15.
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