US3482552A - Fan assembly of the variable air delivery type - Google Patents

Description

9, 1969 MINORU TOYODA ETAL 3,482,553

FAN ASSEMBLY OF THE VARIABLE AIR DELIVERY TYPE Filed Dec. 6, 1967 2 Sheets-Sheet 1 Dec. 9, 1969 MINORU TOYODA ETAL 3,482,552

FAN ASSEMBLY OF THE VARIABLE AIR DELIVERY TYPE Filed Dec. 6, 1967 2 Sheets-Sheet 2 United States Patent O 3,482,552 FAN ASSEMBLY OF THE VARIABLE AIR DELIVERY TYPE Minoru Toyoda and Uichiro Kobashi, Kariya-shi, Japan, assignors to Aisin Seiki Company Limited, Kariya-shi, Aichi-ken, Japan Filed Dec. 6, 1967, Ser. No. 688,598 Claims priority, application Japan, Dec. 7, 1966, 41/ 80,173 Int. Cl. F01p 7/02; F04d 19/02 U.S. Cl. 123-4111 4 Claims ABSTRACT OF THE DISCLOSURE This invention relates generally to a fan assembly of variable air delivery type. More specifically, it relates to improvements relating to a fan assembly, especially suitable for use with an internal combustion engine, for instance, of automotive type.

In the case of the conventional fan assembly adapted for cooling of the automotive engine, fan blades are generally mounted rigidly on a shaft which is preferably connected directly with the cooling water pump fitted on said engine and driven thereby. According to the general practice adopted by those skilled in the art, the design air delivery of the cooling fan assemblyis selected so as to meet the summer season requirements at the engine side. In this kind of fan assembly, the practical air delive ry is increased or decreased depending upon occasional engine speed, if neglecting the cooling effect of the automotive engine obtained from the amount of draft from the radiator grill which will be increased or decreased according to the occasional running velocity of the vehicle. With this kind of cooling fan assembly, on the other hand, the air delivery will naturally and always be that required in summer. Over-delivery of cooling air will thus be encountered, especially in winter, at higher running speeds of the engine where the demand for the fan operation is considerably reduced. This conventional drawback leads to a corresponding power loss, on the one hand, and an over-cooling of the engine, on the other, inviting there by adverse effects upon the durability, thermal efficiency and accelerating performance of the engine.

It is therefore the main object of the present invention to provide a cooling fan assembly adapted for substantially obviating the aforementioned conventional drawbacks.

A further object is to provide an improved cooling fan assembly, capable of effectively preventing over-cooling of the automotive engine at higher running speeds thereof.

Still another object is to provide a cooling fan assembly of the above kind, capable of reducing the power loss caused by otherwise met excess cooling operation at higher engine speeds.

These and further objects, features and advantages of the invention will be more apparent to those skilled in the art from a consideration of the following detailed de- F CC scription when taken together with the accompanying drawings in which:

FIG. 1 is a front view of a fan assembly according to a first embodiment of the invention, illustrative of its stationary position.

FIG. 2 is a longitudinal sectional view of essential parts of the first embodiment, taken substantially along the section line 11-11 in FIG. 1 and illustrative of its operating position at higher running speeds of the engine.

FIG. 3 is a front view of a second embodiment of the invention, illustrative however of its operating conditions at higher speeds of the engine.

FIG. 4 is a longitudinal sectional view thereof, taken substantially along the section line IV-IV in FIG. 3.

Now referring to the accompanying drawings, two preferred embodiments of the invention will be described in detail hereinbelow:

In the first embodiment of the invention shown in FIGS. 1 and 2, the numeral 10 denotes a front ring plate having a plurality of, herein shown four by way of example, radially and outwardly extending arms 10a integral therewith. These arms 10a carry fixedly thereon respective fan blades 11 by welding, bolting, riveting or the like conventional fixing technique, although the fixing means adopted for the purpose have been omitted from the drawing for simplicity thereof. Although not shown, each of the fan blades 11 has an aerofoil cross-section and a certain angle of attack relative to the rotational plane of this front fan which plane can be deemed as that of the drawing, as easily and definitely supposed by those skilled in the art.

A front boss 12 is shaped into a ring plate having a circular shoulder 12a so as to snugly and fixedly mount the ring plate 10 in a precisely concentric manner. The plates 10 and 12 are rigidly united together by a plurality of, herein shown four by way of example, fixing bolts 13. The boss 12 is fixedly mounted on a rotatable shaft 14 at its front or left-hand extremity by pressure fit, when seen in FIG. 2. Naturally, a conventional key may be employed without relying upon the pressure fit technique.

The shaft 14 is operatively connected to the shaft of an engine, preferably an automotive gasoline engine through a belt drive, gearing or the like transmission means, although not shown. Generally, a cooling fan is mounted on the drive shaft of the cooling water pump which drive shaft is connected to the engine shaft through a belt drive so as to be driven thereby.

Rear ring plate 15 is formed integrally with the same number of, also four in this case, radially and outwardly extending arms 16 which are preferably so made as to have a same configuration and peripheral pitch to those of the first or front fan blade series at 11. These arms 16 have fan blades 17 having preferably same configuration and peripheral pitch as well as angle of attack as those for the first fan blade series. Rear ring plate 15 is arranged in parallel with front one at 10, when seen in FIG. 2, keeping however a certain small distance such as 1-5 mm. therebetween, and rigidly mounted on the shoulder formed at 18a on a rear boss 18 and by means of a plurality of fixing bolts 19. The rear boss 18 is rotatably mounted on the shaft 14 by means of a ball hearing 20.

Stop pins 21 apart an angle of degrees in the peripheral direction from each other are fixedly mounted on rear ring plate 15 and slidably received in respective elongated circumferential slots 22 cut through the front ring plate 10.

A spiral spring 23 is fixed at its inner end at 23a in a slot 24 cut diametrally in the shaft 14 and extending axially a certain distance such as 2-3 cm. from the front end of the shaft, when the diametral dimension of the latter is 1.6 cm. The outer end 23b of the spiral spring is fixedly received in an axial slot 25 cut in the inside wall of the hollow rear boss 18. In FIG. 1, the spiral spring 23 is only schematically shown by a dotted line for the purpose of simplicity of the drawing. By the provision of the spiral spring, the rear fan series at 17, together with rear ring plate and rear boss 18, is urged resiliently to turn in clockwise direction when seen in FIG. 1 as hinted by an arrow 26. Thus, stop pins 21 are abutting against the respective extremities of peripheral slots 22 as shown in FIG. 1 when the fan assembly is at rest.

The operation of the fan assembly so far described is as follows.

When the engine is stopping, the fan assembly occupies the position shown in FIG. 1, wherein the blades 17 of the rear fan series are positioned alternatively with those at 11 of the front fan series, under the action of spiral spring 23 as described hereinbefore.

When the engine starts, the shaft 14 is thereby rotated so that both fan series rotate in the clockwise direction when seen in FIG. 1, for the delivery of cooling air streams. During this operation, both fan series are subjected naturally rotational resistance which is substantially proportional with the air delivery. While the front fan series is fixedly mounted relative to the drive shaft 14, thus no relative movement being developed at every speed of the latter, the rear fan series will rotate relative to the front fan series under the influence of said rotational resistance, and against the action of the spiral spring 23 and in the counter-clockwise direction in FIG. 1. Although not binding, the air delivery direction can be deemed to be from left to right in FIG. 2, so as to cool a radiator, not shown, positioned in close proximity to the fan assembly at the left hand extremity of FIG. 2. Theoretically, the term delivery must be sucking or suction.

It is easy to select the urging force of the spring 23 being equal to the rotational resistance which is applied to the rear ring plate- boss assembly 15, 18 at a certain engine speed such as 3,000 rpm. beyond which the cooling demand will be reduced, when assuming the rated max.

allowable speed is 6,000 rpm.

So far as the engine speed kept lesser than the abovespecified predetermined value, both fan series occupy the relative position shown in FIG. 1, so that the full fan drive is completely utilized for the cooling service, and all the fan blades, eight in their number in this case, will function in full degree, and therefore, deliver in general larger amounts of cooling air.

When the engine speed is increased so as to run the vehicle at a higher speed than that corresponding to the above-specified engine speed and the rotational resistance a to which is subjected the rear fan series exceeds beyond a certain value equal to the initial urging force specifically adopted and will start to move in the counter-clockwise direction relative to the front fan series against the urging force exerted by the spiral spring 23 until the occasional and rotational resistance transmitted from the rear fan blade series at 17 to the rear boss 18 is brought into and kept in balance with the increased urging force of the spiral spring 23. In this way, a mutual interference will develop between both fan blade series 11 and 17 and the air sucking amount will reduce in comparison with the said first case, although all the blades operate in the intermediate running speed range under consideration.

With further increase of the engine running speed, a correspondingly larger rotational resistance will be induced in the rear fan series which is therefore rotated still further in the counter-clockwise direction relative to the front fan series, until both series blades 11 and 17 are brought into registration with each other. The position and length of the circumferencial slots 22 relative to the cooperating stop pins 21 are so selected that any further shift of the rear fan series relative to the front one in the above sense may be positively prevented by the engagement of said stop pins with the respective opposite extremities of said guide slots 22. When said relative coincidence with both fan series when seen from the front side of the fan assembly, the latter operates in effect with its four fan blades and the air sucking rate will be still further reduced at this final operating stage than the case of said initial and intermediate operating stages.

It will be clear from the foregoing that with use of the fan asembly according to the first embodiment, the cooling air sucking rate by the fan assembly can be modified in the reducing sense at higher running speeds of the engine and the conventional drawbacks as mentioned hereinbefore can be substantially obviated.

The second embodiment of the present invention shown in FIGS. 3 and 4 is so designed and arranged that the air sucking rate of the fan assembly is controlled in accordance with variations in the temperature of te engine cooling medium such as water, by modifying the relative position of two groups of fan blades.

In FIGS. 3 and 4, the numeral 30 denotes a front ring plate similar to that denoted 10 in the foregoing and formed integral with radially and outwardly extending arms 30a which carry fixedly thereon respective fan blades 31. The ring plate 30 is formed with circumferentially extending elongated guide slots 42 which are similar to those denoted 22 in the foregoing and slidably receiving and cooperating again with stop pins 41. The ring plate 30 is fixedly mounted on a front boss 32 by means of a plurality of fixing bolts at 33, said boss having a central forward projection 32a made integral therewith. This projection 32a is formed with a diametrally and axially exending slot 44 for fixedly receiving the outer end at 43a of spiral spring 43 which is similar to that denoted 23 in the foregoing. The outer end of 43b is mounted positively by a spring mount 60 which is rigidly attached to the free ends of stop pins 41.

Rear ring plate 35 similar to 15 in the foregoing is fixedly connected with rear boss 38 by means of a set of fixing bolts 61. Rear ring plate 35 carries fixedly a plurality of, herein shown in four, rear series blades 37 through arms (not shown) which are similar to those denoted 16 in the foregoing.

A hollow shaft 62 is rotatably mounted by means of two sets of ball bearing 63 which are supported within a stationary extension housing 64 integral with the main housing 65 of an engine cooling water pump generally shown at 66. The impeller at 67, is fixedly mounted on one extremity of the rotatable shaft 62, while the opposite extremity of the latter is formed into a coarse male screw part68 having trapezoidal teeth as shown and kept in meshing relation with a corresponding female screw :part 69 formed on the inside wall surface of front boss 32. The rear boss 38 is pressure fit onto the hollow shaft 62 at a position thereof in close proximity to said screw coupling 68-69. The unitary connection between the boss 38 and the shaft 62 may be relied naturally upon other conventional fixing technique such as keying or the like.

Hollow shaft 62 is formed at its pump side extremity with an axial recess 58 in which, a thermostat assembly 59 is positively positioned by means of a spring clip 57 and a cushion ring 56. Although not shown on.account of its very similarity, the thermostat assembly 59 has a thermostat element contained therein and. arranged to make physical expansion and contraction depending upon the temperature fluctuation of the cooling water prevailing in the interior space of the pump 66 containing the impeller 67. An operating bar shown at 59a is physically connected with'said thermostat element, on the one hand, and with one end of a rigid transmission bar 55, on the other hand, said bar being extending through the longitudinal bore 62a in the hollow shaft and in anonrotatable manner. The free end of the transmission bar 55 abuts against the front boss 32.

The numeral 54 is a driven belt pulley which is rigidly and fixedly connected with rear boss38 by means of said fixing bolts 61. This pulley 54 is connected with a drive pulley mounted fixedly on the engine shaft, although not shown. Sealing ring 53 is separating the interior of the pump housing 65 from that of the extension housing 64, for effectively preventing the cooling water from leaking out of the pump side into the bearing side within the extension housing.

The operation of the second embodiment is as follows:

When the engine runs, rotation is transmitted therefrom through the belt transmission to the driven pulley 54, thence through the bolts 61, rear boss 38 and rear ring plate 35 to the rear fan series at 37. At the same time, rotation will be transmitted from the rear boss 38 through the hollow shaft 62, screw coupling 68, 69, front boss 32 and front ring plate 30 to the front fan series at 31. Naturally, power is transmitted through the hollow shaft 62 to the impeller 67 of the cooling water pump 66, thereby the latter being kept in operation. As in the foregoing first embodiment, ,the spiral spring 43 is designed to be so strong that with the thermostat element contracted, the urging pressure exerted by the spring 43 through its mount 60 and fixing bolts 41 to the rear ring plate 35 as well as the rear fan series 37 will be positively effective to maintain the both fan series 31 and 37 in their mutually overlapping position shown partially by full lines in FIG. 3. Since both fan series rotate in synchronism to each other, it can be well imagined as if they should be kept stationary for better understanding of the present invention.

When the temperature of the engine cooling water prevailing within the cooling pump housing 65 is lower than a predetermined level such as, for instance, 85 C., the thermostat element, not shown, of the assembly 59 is kept in its highly contracted state. The both fan series are kept in their mutually overlapped state, as will be more fully described hereinbelow.

More specifically, at such colder state of the cooling water and the thermostat element is in its contracted state, the free end of the transmission bar 55 is positioned at its most possible right hand one, when seen in FIG. 4, so that the front fan assembly is rotated relative to the rear fan series and in the clockwise direction when seen in FIG. 3 until the both fan series are brought into relatively overlapped position as above referred to. Therefore, in this case, the fan assembly operates in effect with four blades, so as to suck a possible minimum amount of air per unit time. This overlapped position is positively maintained, as in the foregoing embodiment, by the engagement of stop pins 41 with the end walls of the respective guide slots 42, as shown in FIG. 3. Therefore, conventionally met engine over-cooling may be effectively avoided.

When the cooling water temperature should elevate beyond the said predetermined level, the thermostat element will expand and the bar 55 is thereby pushed leftwards in FIG. 4, an axial urging force being applied thereby upon the inner end wall surface of front boss 32 and said axial force being transformed into a cor responding angular movement of the same boss thanks to the provision of coarse screw coupling 68, 69 and against the urging pressure exerted by said spiral spring.

Therefore, rotation is transmitted from the front boss 32 through fixing bolts 33 to front ring plate 30 and front fan series carried thereby. This fan series at 31 will be shifted in the counter-clockwise direction in FIG. 3 against the action of the spring 43 and towards the dotted line position of the fans 37. This fan-shifting force depends naturally upon the excess temperature of the cooling water above the said predetermined value. At the finally shifted position of the front fan series, the fan assembly functions with all the effective fan blades and sucks its maximum possible cooling air quantity and thus otherwise met engine over-heating may be effectively avoided.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof.

For instance, a combination of the both types of embodiments can well be employed when desired, although this combination has not been shown and described.

What is claimed is:

1. In a fan assembly of the variable air delivery type operatively connected through a fan drive shaft and transmission means to an internal combustion engine such as that used in automotive vehicles, said assembly comprismg:

(a) a first fan blade series rigidly mounted on said shaft,

(b) a second fan blade series arranged mechanically in parallel and coaxial relation with said first series and mounted rotatably on said shaft,

(c) a spring means provided between said second series and said shaft, and

(d) relative rotation limiting means provided between said first and said second fan blade series, wherein said first and said second fan blade series rotate whenever said fan drive shaft rotates and the blades of said second series are capable of angular displacement with respect to those of said first series from a position of interspaced relationship to a position of alignment to effectively reduce the number of blades in response to a condition of said engine.

2. A fan assembly as set forth in claim 1, wherein said engine condition is the engine running speed.

3. A fan assembly as set forth in claim 1, wherein said engine condition is the cooling water temperature.

4. A fan assembly as set forth in claim 1, wherein said engine condition is the combination of the engine speed and the cooling water temperature.

References Cited UNITED STATES PATENTS 1,920,883 8/1933 Perkins 12344.49 2,637,308 5/1953 Dodge 12344.12 X 2,982,361 5/1961 ROsen -13524 2,993,483 7/1961 Erickson 12341.l2 3,094,975 6/1963 Muller 12341.12 3,217,849 11/1965 Weir 123-4112 X 3,369,610 2/1968 Dancik 170135.25 3,394,682 7/1968 Bensinger 1234l.12

FOREIGN PATENTS 905,002 9/1962 Great Britain.

AL LAWRENCE SMITH, Primary Examiner U.S. Cl. X.R.

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