US2095491A - Spiral gearing - Google Patents

Description

Oct. 12, 1937. EBEARE I 91 SPIRAL GEARING 1 Filed July 24, 1935 5 Sheets-Sheet 1 Oct. 12, 1937. L. E. BEARE SPIRAL GEARING Filed July 24, 1955 5 Sheets-Sheet 2 z a W M flzlorizeg.

- L. E. BEA

Oct. 12, 1937.

SPIRAL GEARING 5 Sheefsr 3 Filed July 24, 1935 .27 b "anion- Ieozza rd ffieare,

Oct. 12, '1937'. E. BEARE SPIRAL 'GEARING Filed July 24, 1955 5 Sheets-Sheet 5 Patented Oct. 12, 1937 srIRAL GEARING Leonard E. Beare, East Chicago, Ind.

Application July 24, 1935, Serial No. 32,942 V 9 Claims.

and a cooperating external gear adapted to serve as a gear reduction device.

One of the primary objects of the invention is to provide an intermeshing internal gearand cooperating external gear which is adapted to engage the internal gear at diametrically opposed points and eliminate the use of thrust bearings or the like on the external gear shaft.

A further object of the invention is to provide compact pairs of spiral gears whereby power may be transmitted quietly and efficiently at desired shaft angles and at desired gear ratios up or down but preferably down. Due to the sliding surface contact of the teeth, the teeth may be of any des'iredcross section. A further object of the invention is to provide spiral gearing which is adapted for use in rotary pumps for liquids or gases.

Another object of the invention is to provide a rotary pump having but two moving parts and is adapted to pump a fluid with a minimum of turbulence and pulsations. A further object of the invention is to provide a gear transmission wherein an internal ring gear is provided with cross threads adapted to make a sliding, rather th'ana rolling driving connection with an internal 'g'ear.

. I The 'gearingis capable of the use in many dif- 'ferent devic'a'but has been illustrated in a rotary pump adapted for use in a supercharger for an internal combustion engine or the like.

The invention is illustrated in a preferred embodiment in the accompanying drawings in which- Figure 1 is an elevational view showing a rmg gear with cross-slotted teeth in engagement with an external gear, suitable for power transmission and gear reduction; Fig. 2, a broken sectional view of the gearing asshown in Fig. 1; Fig. 3,' a sectional view of the rotary gear pump taken as indicated at line 3 of Fig. 4; Fig. 4, a sectional view of. the pump taken as indicated at .line of Fig. 3; Fig. 5, an elevational view similar "to Fig. 1 but showing a ring gear serving as a rotary .head andapiston-rotortherein; Fig. 6, a broken plan view of the parts shownin Fig. 5; Fig. '7, an *ele vational View similartoFig; 5, the piston-rotor being removed; Fig. 8, a broken sectional view taken as indicated at '1ine:8-8 of Fig. 7; Fig. 9, an end view of the piston-rotor; Fig. 10, an elevational View of the same; Fig. 11, a sectional View taken as indicated at line H of Fig. 9;,Fig. 12, a broken sectional view taken as indicated at line l2-l2 of Fig. 9; Fig.- 13, an elevational view of .the assembled pump; and Fig. 14, a broken sectional view of the same taken as indicated at line ill-M of Fig. 13.

In order to understand the invention, we will 5 refer first to the simple embodiment shown in Figs. 1 and 2 wherein a ring gear I5 is carried by 'a yoke Iii on a drive shaft H. The gear i5 is providedwith cross slots or threads I8 and I9 which intermesh with the teeth or threads 20 provided on the external gear 2 l which is mounted on a shaft 22. As the gear 2! engages the gear [5 at diametrically opposed points, it is necessary for it to engage the slots H3 at one side and the slots 59 on the opposite side. It may be noted that the gears do'not make a rolling contact as in the case of ordinary spur gears, but the contact is sliding and accordingly, the teeth may be of any desired length and cross-section such as dove-tails or the like. It will also be understood that for the particular combination of spiral angles illustrated when the shaft ii is rotated, it will cause the shaft 22 to be rotated at about a three to one ratio. A more general characterization of the invention maybe had by a direct comparison with the so-called spiral gearing which in an analogous case would have spiral gears of equal diameter and spiral angles, mounted externally to each other, so that the gears roll over the surfaces of each other in addition to sliding an equivalent distance across the face of the contacting teeth. This necessitates the conventional rolling clearance to prevent the teeth from interfering and permits but a small area of contact on the teeth. Also, the shafts must lie in parallel planes, which takes additional space for the shafts and gears. With the present construction, the shafts may lie in the same plane and the centers of rotation of the gears will be identical. There is a sliding movement'of one set of teeth between the teeth of the other set but there is no rolling and accordingly there may -be surface contact to substantially the full depth of the teeth. However, if gears of relatively wide radial width are used, it is not feasible to have the surface contact over the entire length of the teeth because the ends of such. spherically shaped gears are rotating in smaller circles than their medial portion. This excessively wide arc -'of contact between the gears gives rise to interference in the same manner as when there is too great a width of contact between an ordinary worm and face of the wormgear.

In the present construction the shafts are also angularl'y disposed and a yoke must be used to rotate the outer gear i5 around the inner gear 2|, and the shafts must intersect at some obtuse angle greater than To prevent the same teeth from contacting through an excessively long are of rotation which would result in a gearing of 1:1 ratio or practically a splined shaft fitting, the useful shaft angles for this type of gearing should not approach too closely to Of the many combinations of spiral angles and gear ratios which are possible for each shaft angle, one of the simplest and most durable has been illustrated. This is the combination in which the spiral angle of one of the gears, preferably that of the external gear i5, is equal to the shaft angle, and only the outer gear needs to have cross-threaded spirals.

There are certain combinations. of spiral angles which are undesirable and inoperable; Since the gears have no mechanical advantage and the speed ratio can only be changed by changing the spiral angle, a reduction greater than 3:1, employing an efiective spiral pitch of roughly 20 is about the limit for efhcient power transmission. For a much larger reduction, the gear would have to be oifset with respect to the shaft 22 to prevent interference with it, and the long gaps in the teeth created by cross-threaded spirals at a small angle to each other makes it difiicult to secure a sufficiently long are of contact with the other gear. Two consecutive spirals of the same right or left-hand direction will not be in contact with the driven gear and the drive would not be smooth or continuous.

In any combinations in which both gears are cross-threaded at spiral angles closely approaching equality, the above condition will again be approached and there will be points throughout the rotation in which the area of contact between the teeth is greatly reduced.

Byproperly enclosing the gear 2i, a certain amount of pumping effect may be obtained by having a ring gear I5 serve as a rotary valve head. The device may be assembled by having a removable sector as will be described in the embodiment below.

The type of gearing shown in Figs. 1 and 2 may be employed in a rotary pump of the type shown in Figs. 3-14 by elongating certain of the gear teeth and deepening the associated slots and enclosing the assembly in a suitable housing.

Referring particularly to Figs. 5-10, it will be seen that a rotary head 23 is provided with internal cross-threads 24 and 25 and a pair of deepened cross-ports 23 and 21 to receive the vanes 28 of the piston-rotor 29 mounted on the shaft 39. If desired, the shaft 38 may be provided with tapering trunnions 3! to fit Within the gear housing described below. The gear 29 is provided with suitable teeth or threads 32 which, when assembled as shown in Figs. 5 and 6, engage slots 24 at one side of the rotary head 23 and slots 25 at the diametrically opposed side. The rotary head 23 is carried by a yoke 33 provided on the driving shaft 34. In the embodiment illustrated, the gearing is so arranged that the head 23 makes three revolutions for one complete revolution of the piston rotor 29. Thus it will be understood that a vane 28, during rotation of the two gears, may pass through the port 25 in the head and the head will make a complete revolution while the same vane makes a third of a revolution and is then ready to pass through the port 21 to the other side of the rotary head 23. The action of the vanes or pistons 28 is the same as that of the teeth 32 except that the parts are longer. This mechanism is housed, as shown in Figs. 3, 4, l3 and 14 by means of a frame 35 which affords a journal 36 for the shaft 34 and to which a pump housing 31 is secured by means of bolts 38. The housing 31 affords journals 39 for the trunnions 3| and is equipped with a removable plate 49 secured in position by means of screws 4!. The housing is further provided with flange members 42 to partially enclose the deep slots 26 and 21 in the rotary head 23. If desired, the flanges 42 may be continued around the housing so that the slots and head 23 are never, exposed. The housing is further provided on each side with an intake port 43 and an exhaust port 44. The two intake ports 43 may be connected together, if desired, and likewise the two exhaust ports 44. These connections are not shown although it will be understood that there is sufficient room between the flanges 42 and the shaft 38 to permit the connecting parts to be installed without interfering with the rotating yoke 33.

In order to facilitate assembly of the device, the gear 29 is provided with a removable sector 45 which is securely held in position by screws 46. Also, the vanes or pistons 28 may be removably secured to the rotor by means of machine screws 4'! as shown in Figs. 9, 11 and 12. In assembling the device, the vanes 28 and sector 45 are removed from the rotor and the cover plate 48 taken off of the housing 31. The open portion of the gear 29 may then straddle the threads 24 and 25 and the head 23 and gear 29 rotated into mesh. The vanes 28 may then be slipped into position through one of the ports 43 and secured into position by means of the screws 41. In like manner, the other vanes may be inserted and the cover plate 40 replaced.

In operation, the shaft 34 may be used to rotate the head 23, and the head 23 will present a port or deep slot 26 through which the vane 28 may pass and will cause the vane to sweep through the housing from the inlet to the exhaust port. The instant the vane clears the head 23, the chamber between the vane and the head will be sealed off except for the intake port 43. After the vane passes the exhaust port 44, the head will present the port 21 to permit the vane to pass back through the head and. commence a pumping operation on the return cycle. All of the vanes operate in the same manner and the action is very smooth and capable of high speed.

If desired, the driving gears, on a pump of this type, may be placed on the shafts 30 and 34 outside of the gear housing. Of course, such gears can be of the spur or beveled type, but it is preferred to use spiral gears inside the housing, as shown.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, but the appended claims should be construed as broadly as permissible, in view of the prior art.

I claim:

1. A pair of intermeshing gears comprising: an internal gear, and an external spur-type gear intermeshing with said internal gear at two diametrically opposed points thereon.

2. Reduction gearing comprising: an internal spiral ring gear, and an intermeshing spur-like gear therein in driving engagement with said internal gear at diametrically opposed points thereon.

4. In combination: an .internal ring gear equipped with slotted crossed teeth; and an external spur-like gear therein having teeth intermeshing with the ring gear teeth at diametrically opposed positions.

5. A pair of intermeshing reducing gears comprising: an internal spiral ring gear having crossed threads; an externally threaded gear having spur-like teeth dove-tailing with the threads of said ring gear at diametrically opposed points. l

6. In combination: an internal ring gear provided with crossed spiral threads of equal spiral angles and opposite hands, and a spur-like gear therein intermeshing with the spiral threads of one hand at one sector and with those of the opposite hand at a diametrically opposed sector.

'7. In combination: a spiral gear equipped with sets of crossed teeth; and a spur-like gear having teeth intermeshing with each of the respective sets of teeth at diametrically opposite positions.

8. A device as specified in claim 7, in which the centers of rotation of both gears are identical, the contacting tooth edges are radial extensions from the center of rotation so that the tooth profiles are' dovetailed in the grooves of the cooperating gear, and the ends of the teeth are spherically concentric with respect to said grooves in the cooperating'gear.

9. A power transmission means comprising: two shafts mounted at obtuse angles in the same plane, means for supporting said shafts, a gear mounted on the intersecting end of one shaft, a second gear mounted on the second shaft at the point of shaft intersection, and diametrically opposed toothed driving contact'between the two gears.

LEONARD E. BEARE.

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