GEARING WITH DUPLEX FLOATING TOOTHED PORTIONS

Abstract

A gearing with duplex floating toothed portions for transmission between either two parallel shafts or two intersecting shafts comprising two meshing gears(12) and (14) one gears (14) having coaxially disposed toothed portions (16) and (18) interacting with component (20) by spiral joints (22) and (24) different characteristics and an arrangement limitative divided spiral motions of toothed portions (!6) and (18) relatively component (20) by parting plane “A” and arresting device (26). Both toothed portions (16) and (18) of gear (14) and meshing gear (12) have mating teeth whereby both toothed portions (16) and (18) are coupled positively with component (20). Even distribution of applied force between toothed portions (16) and (18) or elimination of the free angular displacement of the gear (12) and (14) with respect to each other within backlash are provided by choice of characteristics of spiral joints (22) and (24).

Description

BACKGROUND

[0001] 1. Field of Invention

[0002] This invention relates to gearing with a split gear having two toothed portions.

[0003] 2. Description of Prior Art

[0004] In symmetrical double helical or herringbone type gears the tooth meshing errors cause the uneven distribution of applied load between the two toothed portions of the gear.

[0005] Accordingly, efforts have been made when designing double toothed helical gears to eliminate or at least to reduce these disadvantages. For example, in U.S. Pat. No. 3,102,433 there is disclosed a gear mechanism wherein one gear is axially fixed. The other gear is a free move axially along its shaft or axially together with its shaft. Each gear comprises of two toothed portions. The teeth of the first toothed portion having the smaller inclination angle in one direction have the greater normal pressure angle. The teeth of the second toothed portion having the greater inclination angle in the opposite direction have the smaller normal pressure angle. The substantially greater part of applied load is taken-up permanently by the toothed portion having the lesser helix angle. This gearing is less sensitive to the variations of load-distribution due to mesh errors than is the gearing of the symmetrical herringbone type.

[0006] Such gearing having the toothed portions which are fixed to each other, however, exhibits the following disadvantages:

[0007] (a) Effective face width is the same as a typical gearing. For increasing loading ability there is a need to increase a center distance. The weight of the gear assembly will increase too.

[0008] (b) The technological process of manufacture of the teeth of the gears is expensive.

[0009] (c) Presence of dynamic load on the gear teeth particularly for high-speed gearing.

[0010] For high-speed gearing unavoidable inaccuracies in the tooth mesh due to tolerance, as well as errors in manufacturing and assembly, lead to high-frequency periodic accelerations of the driven gear. These accelerations result in the imposition of acceleration forces on the meshing teeth. Due to the presence of backlash between non-working tooth flanks, the acceleration of the driven gear leads also to separation of the working teeth followed by a reengagement. As a result, impact load impose on the gear teeth. This phenomenon, known as free impact or hammering, results in high dynamic loading on the gear teeth with attendant noise generation and vibration occurring.

[0011] An example of anti-backlash gearings are presented in U.S. Pat. No. 4,612,816. Each gear has coaxially disposed first and second toothed portions. The teeth of the first toothed portion have a first inclination angle. The teeth of the second toothed portion have a second inclination angle. Preloading means urge of the floating gear against the fixed gear. The teeth of the first toothed portion of the floating gear mesh with the teeth of the first toothed portion of the fixed gear. The teeth of the second toothed portion of the floating gear intermesh with the teeth of second toothed portions of the fixed gear along the opposite tooth flanks with respect to each other.

[0012] Such gear assembly does, however, exhibiting certain disadvantages:

[0013] (a) Preloading means have a large, complex design, and complex adjustment.

[0014] (b) Such gear assembly can be used only in non-reversible one stage gear set.

[0015] (c) Manufacture of the gear assembly is expensive.

OBJECTS AND ADVANTAGES

[0016] Basic objects and advantages this invention are:

[0017] (a) to provide even distribution of an applied load between the floating toothed portions for increasing the loading ability of the gearing without increasing of a center distance. The weight of the gear assembly will increase insignificantly. Service life will stay the same.

[0018] (b) to provide smooth working of the gearing.

[0019] (c) to eliminate dynamic load on the gear teeth for high-speed reversible gearing without the use of toothed portions with different helix angles and the means for preloading.

[0020] Other objects and advantages are to enable the use of the invention for gearing of any classification and in reversible multi-stage gear assembly.

DRAWING FIGURES

[0021] The invention will be more particularly described in the following discussion of the preferred embodiments thereof for with reference to the accompanying drawing wherein.

[0022] FIG. 1 is an elevational view, partly in section, showing a gear housing incorporating the inventive concept hereof for transmission between parallel and intersecting shafts.

[0023] FIGS. 2 and 2A are the diagrammatic illustrations of the engagement of the teeth of the gears and of the contact in the thread joints of the gear assembly 1 of FIG. 1. The thread joints have the opposite directions.

[0024] FIGS. 3 and 3A are the diagrammatic illustrations of the interengagement of the teeth of the gears and of the contact in the thread joints of the gear assembly 1 of FIG. 1. The thread joints have the same direction but different lead angles.

SUMMARY

[0025] In accordance with present invention a gearing with duplex floating toothed portions comprises a plurality of meshing gears one of which having coaxially disposed two floating toothed portions interacting with component by spiral joint and arrangement limitative divided spiral motions of toothed portions relatively component.

Description—FIGS. 1 to 5

[0026] FIG. 1 shows the elevation view of a gear assembly 10 for the transmission between two parallel shafts is comprised of meshing herringbone gears 12 and 14. The gears may be formed either as spur or as helix. Gear 12 is mounted fixedly to a shaft 32 by means well known in the art. Gear 12 cut on separate blanks or may be cut on single blank. Gear 14 is formed with coaxially disposed toothed portions 16 and 18. The toothed portions mounted to a component 20 interact with it by spiral joints, for example, by the right-hand and left-hand ball double thread joints 22 and 24. Component 20 is mounted to its shaft 34 by means well known in the art.

[0027] Gear 14 has an arrangement which limits the divided axial motions of toothed portions 16 and 18. The oncoming motions of toothed portions 16 and 18 are limited by contact between them along a parting plane “A”. The counter motions of toothed portions 16 and 18 are limited by an arresting device 26. Arresting device 26 consists of pins 28 and retaining rings 30. A mounting of pins 28 provides the spiral motions of toothed portions 16 and 18. The spiral motions must continue till of an engagement of teeth 48 and 50 of gear 12 with teeth 52 and 54 of toothed portions 16 and 18, as illustrated in FIGS. 2 and 2A.

[0028] Shafts 32 and 34 are each rotatably supported along parallel axes by bearing 36 and 38 and 40 and 42 mounted in a housing 44 and a cover 46 respectively.

[0029] As illustrated in FIGS. 2 and 2A the directions of the helixes of teeth 52 and 54 and of thread joints 22 and 24 must be opposite for each toothed portions 16 and 18 respectively. It is necessary that each of the toothed portions make the spiral motion relatively of component 20. The spiral motions must continue till of the engagement of teeth 48 and 50 of gear 12 with teeth 52 and 54 of toothed portions 16 and 18 respectively.

[0030] As illustrated in FIG. 3 and FIG. 3A, toothed portions 16 and 18 are mounted to component 20 by right-hand ball double thread joints 22 and 24. These thread joints have the same direction but the different lead angles &lgr;1 and &lgr;2 thereto &lgr;1>&lgr;2. Therefore the axial displacement per revolution of toothed portion 16 is more than the axial displacement of toothed portion 18. As a result, by the axial displacement toothed portion 16 pushes or pulls of portion 18. Teeth 50 of gear 12 will mesh with teeth 52 of gear 14. Teeth 50 of gear 12 will intermesh with teeth 54 of gear 14 along the opposite tooth flanks.

[0031] These thread joints 22 and 24 are overhauling. The following equation (a) shows that thread joint is overhauling: 1 d m ⁢ ( f r ⁢ π ⁢   ⁢ d m - L π ⁢   ⁢ d m + f r ⁢ L ) + f c ⁢ d c < 0 ( a )

[0032] Where:

[0033] dm—diameter of contact in thread joints

[0034] fr—coefficient of rolling friction in the thread joints

[0035] fc—coefficient of friction between the toothed portions

[0036] dc—average diameter of contact between the toothed portions

[0037] L—lead of thread

dc≈1.2dm(b)

[0038] after substituting (b) into (a) and simplifying with little error 2 f f + 1.2 ⁢   ⁢ f c < L π ⁢   ⁢ d m ( c ) 3 tg ⁢   ⁢ λ = L π ⁢   ⁢ d m ( d )

[0039] where &lgr;—lead angle

[0040] after substituting (d) into (c)

fr+1.2fc<tg&lgr;(e)

[0041] In FIG. 2 and FIG. 2A, and FIG. 3, and FIG. 3A an arrow 56 indicates of the direction of a rotation of gear 14. Arrows 58 and 60 indicate of the directions of axial forces W62 and W64 An arrows 62 and 64 indicate of the directions of the tangential forces Q62 and Q64. The axial force W is calculated accordingly to the following equation (f): 4 W = F n ⁢ d 1 ⁢ 1 [ d m ⁢ ( f r ⁢ π ⁢   ⁢ d m ± L ⁢   ⁢ cos ⁢   ⁢ α n π ⁢   ⁢ d m ⁢ cos ⁢   ⁢ α n ∓ f r ⁢ L ) + f c ⁢ d c ] ( f )

[0042] where:

[0043] Fn—force normal to the teeth

[0044] d1—diameter of pitch circle

[0045] &agr;n—thread angle

[0046] after simplifying with little error

cos &agr;n=1 5 W = F n ⁢ d 1 ⁢ 1 [ d m ⁢ ( f r ⁢ π ⁢   ⁢ d m ± L π ⁢   ⁢ d m ∓ f r ⁢ L ) + f c ⁢ d c ] ( g )

[0047] The tangential force Q is calculate accordingly to the following equation (h) 6 Q = W ⁢ ( f r ± L π ⁢   ⁢ d m 1 ∓ f r ⁢ L π ⁢   ⁢ d m ) ( h )

[0048] FIG. 1, there is depicted shows a gear assembly 70 for the transmission between two intersecting shafts 80 and 32, one of which is the drive shaft and the other of which is the driven shaft. Gear assembly 70 is comprised of first and second meshing bevel gears 72 and 74. Gear 72 is fixedly mounted to shafts 80. Gear 74 is formed of coaxially disposed spiral floating toothed portions 76 and 78. Toothed portions 76 and 78 mounted to shaft 32 interact with it by spiral joints. Shaft 32 is the component of gear 74. The mounting and the operation of the bevel gearing are the same as the gearing with the parallel shafts therefore I do not describe its mounting and operation.

Operation—FIGS. 1 to 5

[0049] Referring now to FIG. 2 wherein teeth 48 and 50 of gear 12 mesh with teeth 52 and 54 of toothed portions 16 and 18 of gear 14 respectively. Arrow 56 indicates of the direction of the rotation of gear 14 by the action of an applied force. As a result, axial forces W58 and W60 and the tangential forces Q62 and Q64 are generated in thread joints 22 and 24 at their contacting surfaces. The forces W58 and W60 are the reason for contact between toothed portions 16 and 18 along the parting plane “A”. Forces Q62 and Q64 are the reason for the engagement of teeth 52 and 54 of toothed portions 16 and 18 with teeth 48 and 50 of gear 12 respectively. The resultant of the forces W58 and W60 must be equal zero. The applied force distributes between toothed portions 16 and 18 in proportion to the relationship between the tangents of the lead angles &lgr;1 and &lgr;2 of thread joints 22 and 24. Each toothed portions 16 and 18 of gear 14 will be coupled positively with component 20 by thread joints 22 and 24.

[0050] Supposing teeth 52 or 54 one of toothed portions 16 or 18 do not engage with teeth 48 or 50 of gear 12 respectively. The toothed portion the teeth of which mesh with the teeth of gear 12 has a conditional name “first toothed portion”. The toothed portion the teeth of which do not engage with the teeth of gear 12 has the conditional name “second toothed portion”. As a result, by the action of the applied force “first toothed portion” makes the spiral motion relatively of component 20. At the same time “first toothed portion” pushes “second toothed portion” which makes the spiral motion relatively component 20 too. The pushing force is equal the axial force W and acts at the parting plane “A”. The spiral motions of the toothed portions will continue till of the engagement of the teeth “second toothed portion” with the teeth of gear 12. Now the gearing is working as illustrated in FIG. 2.

[0051] Referring now to FIG. 2A, wherein arrow 56indicates of the direction of the rotation of gear 14 by the action of the applied force. All forces W58 and W60 and Q62 and Q64 have the opposite direction relatively of forces W58 and W60 and Q62 and Q64 illustrated in FIG. 2. As a result, toothed portions 16 and 18 contact with retaining rings 30 of arresting device 26 along their contacting surfaces. The operation of thread joints 22 and 24 is the same as FIG. 2 therefore I do not describe it.

[0052] Referring now to FIG. 3 wherein teeth 48 of gear 12 mesh with teeth 52 of toothed portion 16. Teeth 50 of gear 12 intermesh wit teeth 54 of toothed portion 18 along the opposite tooth flanks with respect to each other. Free angular displacement of gears 12 and 14 within backlash are prevented and possibility of hammering is eliminated. Arrow 56 indicates of the direction of the rotation of gears 14 by the action of the applied force. As a result, the axial forces W58 and W60 and the tangential forces Q62 and Q64 are generated in thread joints 22 and 24 at their contacting surfaces. Forces W58 and W60 are the reason for contact between toothed portions 16 and 18 along the parting plane “A”. Force Q62 is the reason for the engagement of teeth 48 of gear 12 with teeth 52 of gear 14. Force Q64 is reason for the interengagement of teeth 50 of gear 12 with teeth 54 of gear 14 along the opposite tooth flanks with respect to each other. The resultant of forces W58 and W60 must be equal zero. The applied force distributes between toothed portions 16 and 18 in proportion to the relationship between the tangents of the lead angles &lgr;1 and &lgr;2 of thread joints 22 and 24. Each toothed portions 16 and 18 of gear 14 will be coupled positively with component 20 by thread joints 22 and 24.

[0053] Supposing teeth 54 of toothed portion 18 do not interengage with teeth 50 of gear 12. As a result, by the action of the applied force toothed portion 16 makes the spiral motion relatively of component 20. At the same time it pushes toothed portion 18 which makes the spiral motion relatively component 20 too. The pushing force is equal axial force W and acts at the parting plane “A”. The spiral motions of toothed portion 16 and, consequently, of toothed portion 18 will continue till of the interengagement of the teeth of toothed portion 18 with the teeth of gear 12. Now the gearing is working as illustrate in FIG. 3.

[0054] Referring now to FIG. 3A, wherein arrow 56 indicates of the direction of the rotation of gear 14 by the action of the applied force. All forces W58 and W60 and Q62 and Q64 have the opposite direction relatively of forces W58 and W60 and Q62 and Q64 illustrated in FIG. 3. As a result, toothed portions 16 and 18 contact with retaining rings 30 of arresting device 26 along their contacting surfaces. The operation of thread joints 22 and 24 is the same as FIG. 3 therefore I do not describe it.

Conclusion, Ramification and Scope

[0055] Accordingly the reader will see that the gearing with duplex floating toothed portions of this invention for the transmission can be used:

[0056] to provide even distribution of applied load between the toothed portions for increasing loading ability of a typical gearing without increasing of a center distance, but with increasing of effective face width of the gears. The weight of the gear assembly will increase insignificantly. Service life of the gearing with increased load will stay the same.

[0057] to provide smooth working of the gearing

[0058] for high-speed gearing to eliminate dynamic loading on the gear teeth without the use of the toothed portions having different helix angles and preloading means.

[0059] Furthermore, such invention has the additional advantages in that, it can be used in the reversible multi-stage transmission of any specification.

[0060] Although only a few exemplary above contains many specificities these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention. For example, the gear with the floating toothed portions can be used as an idler, can be coupled with its shaft by a coupling, the spiral joints and the arrangement can have other design etc.

[0061] Thus the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by examples given.

Claims

1. A gearing with duplex floating toothed portions having a plurality of meshing gears, characterized by:

a) one of said gears is provided a component with two spiral sections of different characteristics,

b) said gear is provided coaxially disposed two toothed portions having spirals are supposed for interaction with the spiral sections of the component,

c) an arrangement of said gear limitative divided spiral motions of the toothed portions relatively of the component,

thereby each the toothed portions of said gear and at least one of said meshing gear will have mating teeth, selected from the group consisting of engaging and interengaging teeth

whereby each the toothed portions will be coupled positively with the component by spiral joints.