Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16H—GEARING
  • F16H55/00—Elements with teeth or friction surfaces for conveying motion; Worms, pulleys or sheaves for gearing mechanisms
  • F16H55/02—Toothed members; Worms
  • F16H55/22—Toothed members; Worms for transmissions with crossing shafts, especially worms, worm-gears
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16H—GEARING
  • F16H1/00—Toothed gearings for conveying rotary motion
  • F16H1/02—Toothed gearings for conveying rotary motion without gears having orbital motion
  • F16H1/04—Toothed gearings for conveying rotary motion without gears having orbital motion involving only two intermeshing members
  • F16H1/12—Toothed gearings for conveying rotary motion without gears having orbital motion involving only two intermeshing members with non-parallel axes
  • F16H1/16—Toothed gearings for conveying rotary motion without gears having orbital motion involving only two intermeshing members with non-parallel axes comprising worm and worm-wheel
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16H—GEARING
  • F16H1/00—Toothed gearings for conveying rotary motion
  • F16H1/02—Toothed gearings for conveying rotary motion without gears having orbital motion
  • F16H1/04—Toothed gearings for conveying rotary motion without gears having orbital motion involving only two intermeshing members
  • F16H1/12—Toothed gearings for conveying rotary motion without gears having orbital motion involving only two intermeshing members with non-parallel axes
  • F16H1/18—Toothed gearings for conveying rotary motion without gears having orbital motion involving only two intermeshing members with non-parallel axes the members having helical, herringbone, or like teeth
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16H—GEARING
  • F16H3/00—Toothed gearings for conveying rotary motion with variable gear ratio or for reversing rotary motion
  • F16H3/44—Toothed gearings for conveying rotary motion with variable gear ratio or for reversing rotary motion using gears having orbital motion
  • F16H3/72—Toothed gearings for conveying rotary motion with variable gear ratio or for reversing rotary motion using gears having orbital motion with a secondary drive, e.g. regulating motor, in order to vary speed continuously

Definitions

• the present invention relates generally to speed reducers, and more particularly to those with very low ratios and a unique worm/worm gear transmission which is able ' to transmit higher torque levels and provide more efficient motion than prior art transmission devices.
• This invention relates also to a combined transmission system that transmits input mechanical power into a unidirectional output. For this purpose, there are two main systems available:
• Transmissions are utilized to transmit rotation for a variety of purposes.
• the term "transmission" as utilized in this application does not specifically refer to a vehicle transmission, although it would extend to such transmissions. Rather, this invention extends to any system wherein a source of movement is transmitted through a driving member to move a driven member.
• a helicopter rotor drive As is known, one of the biggest problems associated with helicopter rotor drives is noise. When compared to conventional non-parallel shaft gear transmissions, worm/worm gear type transmissions generate minimum noise. However, low efficiency and torque capacity associated with prior art worm/worm gear transmissions prevented their use in helicopter power transmission systems.
• Worm/worm gear transmissions in particular double enveloping speed reducers or cone drive worm/worm gears, are well known in the mechanical power transmission field.
• the worm gear is driven by the rotation of the worm with which it meshes.
• the rotational speed of the associated shaft of the worm gear is a function of the number of teeth on the worm gear and the number of threads on the worm.
• the worm may be single or multiple threaded.
• the prior art worm/worm gear transmission had a worm gear with twenty-four or more teeth.
• the American National Standard "Design of Industrial Double-Enveloping Wormgears" (ANSI/AGMA-6030-C87) recommends twenty-four as the minimum number of gear teeth.
• the enveloping angle of any known worm gear for one revolution of the thread of the worm is not more than 15 degrees.
• the enveloping worm gear has a surface that is generated by the profile of an enveloping thread of the worm.
• the term "generated” describes how the profile of the worm gear tooth can be defined. It could utilize mathematical calculations defining the profile from equations of the surface of the enveloping worm thread; hobbing of a gear blank by a tool having the profile of the worm thread; or via computer modeling where the profile of a three-dimensional solid worm gear is cut by the profile of a three-dimensional solid worm thread.
• Conventional enveloping worm/worm gear transmissions did not use worm gears with less than twenty- four enveloping type gear teeth due to the undercut on the root of the tooth.
• the enveloping angle of the worm is the angle of area contact between the threads on the worm and worm gear teeth.
• the enveloping angle is the angle between the ends of the worm thread defined with reference to the center of the worm gear.
• the maximum number of engaging gear teeth is two.
• the enveloping angle should be twice as big as the angular pitch of the worm gear. For example, an enveloping angle of a single thread worm for a worm gear with six teeth is 60 degrees while the enveloping angle of a double thread worm for a worm gear with six teeth is 120 degrees.
• Enveloping worm/worm gear transmissions having less than twenty-four teeth have not been commercially used since it was universally believed that it was not possible to build such a transmission due to undercut on the root of the worm gear tooth.
• the enveloping worm/worm gear transmission of the present invention utilizes a worm gear without undercut gear teeth because of a greater enveloping angle for one revolution of the worm thread.
• the minimum ratio for one thread could be reduced to two, with an achieved efficiency for this invention of up to 99 percent.
• prior enveloping worm/worm gear transmissions had a minimum ratio of twenty- four for one thread of the worm and a ratio of five for five threads of the worm.
• the efficiency of the new worm/worm gear transmission is even greater than in well-known hypoid gearing, which is used in low ratio right angle drives.
• the present invention can replace hypoid or bevel gearing in many applications by reason of the low ratio.
• this new worm/worm gear transmission is able to back drive by transmitting torque from the worm gear to the worm.
• this invention has more than twice the capacity of traditional hypoid gearing.
• the worm can be half or less than half of a split worm, which can have only one supporting shaft.
• the worm gear can be half or less than half of a split worm gear, which can have only one supporting shaft. Using only half or less than a half of the split worm gear or worm enables easier assembling of the worm with the worm gear.
• the present invention describes the effect of "self- lock" between a worm and worm gear which is used for designing a one way clutch.
• the term "self-locking" as is utilized in this application to describe the inventive worm and worm gear combination requires that the teeth of the worm gear when in contact with the thread of the worm, are incapable of rotating the worm about its axis.
• the worm and worm gear combination is incorporated into a system wherein the worm is mounted for rotation in a rotor.
• the rotor surrounds a driving worm gear.
• a rotational input is applied to the worm gear.
• the worm gear teeth engage the thread on the worm, the worm and the rotor rotate about the axis of the worm gear. This rotation is without relative movement between the engaged teeth of the worm and worm gear.
• An auxiliary motor (or an on/off clutch) is preferably mounted on the rotor, and rotates the worm relative to the worm gear to either return the worm gear to its original position, or allow the worm gear to move relative to the worm when an oscillating input is utilized.
• the worm and rotor act as a mechanical diode, resulting in a single direction output.
• the base of the design is a grounded rotor which is holding the worm. Due to this, there is no problem connecting the electrical connections to the operative members even when the operative members freely rotate more than 360 degrees. Balancing of the rotor also becomes easy.
• Versions of designs with a worm gear attached to the different members of the spider differential and bevel differential are the foundations of the invention. Transmissions with different ratios are provided as combinations of these designs. Examples, shown in this patent application are not described in the parent patent application. The usage of this invention not only transmits the rotation utilizing an oscillating input but also transmits the torque for the conventional power transmission. For example, this system can be utilized as part of a vehicle transmission or a gear box with changeable ratio.
• Figure 1 is a cross-sectional view of a worm/worm gear transmission with the worm gear having three teeth according to the principles of the present invention
• Figure 2 is a side view of a worm/worm gear transmission with the worm gear having six teeth according to the principles of the present invention
• Figure 3 is a side view of the worm/worm gear transmission with the worm gear being shown in cross- sectional view;
• Figure 4 is a side view of an enveloping worm with two threads for generation of a profile of a worm gear
• Figure 5 illustrates the use of an enveloping thread for the generation of the profile of the teeth of the worm gear
• Figure 6 is a view of a shortened thread for the generation of a profile of the teeth of the worm gear
• Figure 7 is a side view of an enveloping worm gear according to the principles of the present invention.
• Figure 8 is a side view of a modified worm gear with driving shaft having support from one side of the worm gear
• Figure 9 shows a side view of a worm/worm gear transmission with modified worm
• Figure 10 is a side view of a worm/worm gear transmission with a driving shaft having support from one side of the worm;
• Figure 11 shows a side view of a worm/ orm gear transmission with a modified worm in an off-center position;
• Figure 12 shows a side view of a worm/worm gear transmission with two modified worms in off-center position
• Figure 13 shows a side view of a worm/worm gear transmission with two modified worms placed on the same axis of rotation and connected to the same drive shaft;
• Figure 14 shows a side view of a worm/worm gear transmission with two modified worms placed on different axes of rotation;
• Figure 15 shows an enveloping worm gear with a different profile of teeth
• Figure 16 shows a side view of a worm/worm gear transmission with two enveloping worms placed on different axes of rotation;
• Figure 17 is a perspective view of the worm/worm gear transmission shown in Figure 1 with three worm gear teeth
• Figure 18 is a perspective view of the worm/worm gear transmission shown in Figure 2 with six worm gear teeth and two threads on the worm;
• Figure 19 is a perspective view of a worm/worm gear transmission with ten worm gear teeth and with a single thread worm;
• Figure 20 is a perspective view of a worm/worm gear transmission with nine worm gear teeth and a modified worm having three threads on the worm;
• Figure 21 is a perspective view of a worm gear with six teeth with darkened spots illustrated on the surface of the teeth to illustrate the contact surface with the worm in mesh;
• Figure 22 is a perspective view of a worm with two threads with darkened spots illustrated on the surface of the thread to illustrate the contact surface with the worm gear in mesh;
• Figure 23 illustrates the size difference of the worm/worm gear transmission of Figure 20 in comparison to the size of a typical hypoid type gear
• Figure 24 is a cross-sectional view of a worm/worm gear transmission of the present invention with a gear train comprising an on/off clutch;
• Figure 25 is a cross-sectional view of a worm/worm gear transmission of the present invention with a gear train comprising the on/off clutch and a flexible shaft;
• Figure 26 is a cross-sectional view of a worm/worm gear transmission of the present invention with a pulley drive comprising the on/off clutch and the flexible shaft;
• Figure 27 is a cross-sectional view of a spider differential with a sun gear being connected to a worm/worm gear transmission incorporating the principles of the present invention;
• Figure 28 is a cross-sectional view of a spider differential comprising a ring gear and with a sun gear being connected to the worm gear of a worm/worm gear transmission according to the principles of the present invention
• Figure 29 is a cross-sectional view of a spider differential with the ring gear being connected to the worm gear of a worm/worm gear transmission according to the principles of- the present invention
• Figure 30 is a cross-sectional view of a spider differential with the carrier being connected to the worm gear of a worm/worm gear transmission according to the principles of the present invention
• Figure 31 is a cross-sectional view of a spider differential comprising a ring gear with the carrier being connected to the worm gear of a worm/worm gear transmission according to the principles of the present invention
• Figure 32 is a cross-sectional view of a bevel differential with a bevel gear connected to the worm gear of a worm/worm gear transmission according to the principles of the present invention
• Figure 33 is a cross-sectional view of a bevel differential with a carrier being connected to the worm gear of a worm/worm gear transmission according to the principles of the present invention
• Figure 34 is a cross-sectional view of a bevel differential with the carrier being connected to a first worm gear and the bevel gear being connected to a second worm gear of a pair of worm/worm gear transmissions according to the principles of the present invention
• Figure 35 is a cross-sectional view of a spider differential with the carrier being connected to the first worm gear and the sun gear being connected to the second worm gear of a pair of worm/worm gear transmissions according to the principles of the present invention
• Figure 36 is a cross-sectional view of a spider differential with the sun gear being connected to the first worm gear and the ring gear being connected to the second worm gear of a pair of worm/worm gear transmissions according to the principles of the present invention
• Figure 37 is a cross-sectional view of a spider differential with the carrier being connected to the first worm gear and the ring gear being connected to the second worm gear of a pair of worm/worm gear transmissions according to the principles of the present invention
• Figure 38 is a cross-sectional view of a spider differential with the carrier being connected to the first worm gear and the sun gear being connected to the second worm gear of a pair of worm/worm gear transmissions according to the principles of the present invention with a gear train comprising an on/off clutch;
• Figure 39 is a cross-sectional view of a spider differential with the carrier being connected to the first worm gear and the sun gear being connected to the second worm gear of a pair of worm/worm gear transmissions according to the principles of the present invention with means, comprising a gear train with an on/off clutch and an auxiliary motor;
• Figure 40 is a cross-sectional view of the bevel differential with the sun gear being connected to the first worm gear and the ring gear being connected to the second worm gear of a pair of worm/worm gear transmissions according to the principles of the present invention
• Figure 41 is a cross-sectional view of a bevel differential being connected to the first worm gear and the second worm gear of a pair of worm/ orm gear transmissions according to the principles of the present invention with one fixed rotor;
• Figure 42 is a cross-sectional view of the spider differential and bevel differential being connected to the first worm gear and the second worm gear of a pair of worm/worm gear transmissions according to the principles of the present invention with two fixed rotors;
• Figure 43 is a cross-sectional view of the worm gear with the teeth engaging the thread on a part of split worm of a worm/worm gear transmission according to the principles of the present invention
• Figure 44 is a cross-sectional view of congruent surfaces of the lands on the half of the worm and the teeth of the worm gear;
• Figure 45 is a cross-sectional view of a split worm and worm gear with a train of a torsion spring with a friction clutch;
• Figure 46 is a cross-sectional view of two split worms and a worm gear with two trains of the torsion spring with the friction clutch;
• Figure 47 is a side view of a worm/worm gear transmission with the worm being bodiless;
• Figure 48 is a side view of a bodiless enveloping worm as shown in Figure 47;
• Figure 49 is a side view of a bodiless enveloping worm with a support member being provided to support the worm threads;
• Figure 50 is a side view for a bodiless part of split worm having a support member to support the ends of the worm threads ;
• Figure 51 is a perspective view of a double enveloping worm/worm gear transmission illustrating the orientation of the worm and worm gear for engagement with one another.
• FIG. 1 One embodiment of a worm/worm gear transmission 8 of the present invention is illustrated in Figure 1.
• the transmission has an enveloping type worm 10 with at least one screw thread 12.
• the enveloping type worm 10 is supported on a shaft 13.
• Thread 12 is engaged by at least one tooth 14 of an enveloping type worm gear 16 having three teeth 14.
• the enveloping worm 10 has a single thread 12 in a preferred embodiment and the worm gear 16 has three teeth 14 spaced about its circumference.
• a gap "G" exists between any tooth on worm gear 16 and threads on enveloping worm 10.
• Enveloping worm 10 wraps around enveloping worm gear 16, and enveloping worm gear 16 also wraps around enveloping worm 10.
• the minimum ratio between the number of teeth on the worm gear and the one thread on the worm is two. Accordingly, by rotation of the worm gear, the worm rotates with higher speed.
• Worm gear 16 and worm 10 are preferably enclosed in a housing (not shown) in Figure 1.
• the housing is made from metal and forms a reservoir for a lubricant to both lubricate and cool the gears, bearings, and seals for the unit.
• the housing forms a rigid support to mount the gears, bearings, seals and their associated parts (not shown) .
• Figure 17 is a perspective view which corresponds with the worm/worm gear transmission 8 shown in Figure 1 which includes an enveloping worm 10 having a single thread 12 and a worm gear 16 having three gear teeth 14.
• the reason for using an enveloping-type of worm gear is that this type of worm gear has a natural profile of tooth surface which is distinct from other types of thread followers.
• the configuration of the worm gear teeth is generated by the profile of the thread or threads of the worm.
• a computer model simulation can be utilized to generate the configuration of the worm gear teeth of the worm gear.
• the worm gears can then be formed using known techniques such as hobbing or casting.
• the profiles of the worm teeth is different .
• the main advantage for using the enveloping-type of worm gears is more torque capacity.
• the worm thread has a rolling action contact relationship with the teeth of the worm gear which provides an increased efficiency. Furthermore, it is beneficial to have the pitch diameter in the center portion of the worm on the same order as the pitch diameter in the center of the worm gear. With standard worm designs, having more than one thread and a large enveloping angle, the inability to assemble the worm and worm gear was considered a major obstacle. With the worm and worm gear of the present invention, the worm and worm gear are easily assembled by properly orienting the worm thread and worm teeth as illustrated in Figure 51.
• the worm 160 having two threads 162 is shown oriented so that a worm gear tooth 164 is brought directly into engagement with the worm threads 162 from a radial direction so that the two adjacent worm gear teeth 166, 168 are brought only into partial engagement with the threads 162 from one side (166A, 168A) of the gear teeth 166, 168 of the worm gear 170.
• the distance between the threads 162 is large enough to receive the teeth of the worm gear 170 when brought directly into engagement.
• FIG 2. This transmission has an enveloping worm 22 with two identical screw threads 24.
• FIG. 1 shows an enveloping angle of 120 degrees for the enveloping worm thread 24 that is used for generation of the six teeth 28 on worm gear 26.
• This enveloping worm thread 24 has one revolution of thread or 360 degrees of revolution around its axis of rotation.
• the worm thread's ends have the same cross-sections but could be placed from one position to another position, which is a distinct 120 degrees. This is possible by movement of the cross-section of the worm from one end along the worm thread 24 to another end. In this case, the cross-section will rotate 360 degrees around the axis of rotation for shaft 32.
• the enveloping worm/worm gear transmission of the present invention provides for a worm gear having fewer than twenty-four teeth and also provides surface contact between the thread of the worm and the teeth of the worm gear as illustrated in Figures 21 and 22.
• Figure 21 illustrates two surface contact spots 100a, 100b for a worm gear 26 having six teeth 28.
• Figure 22 illustrates two corresponding surface contact spots 102a, 102b for a worm 22 with two threads 24.
• Figure 6 shows a worm thread 38 for generation of worm gear teeth which is a shortened portion of a thread having an enveloping angle of 120 degrees.
• Figures 7 shows a side view of the enveloping worm gear 26 with six teeth 28.
• Figure 8 shows an enveloping worm gear 44 having six teeth 34 which is modified from the worm gear 26 shown in Figure 7 by shortening the gear along its axis of rotation around drive shaft 46.
• the worm gear 44 could be longitudinally split into two halves and using only one shortened part or generated worm gear from blank, which is already shortened.
• Modified worm gear 44 is easy to assemble in a single reduction unit. This is very important for gears with a small pressure angle when it is difficult to assemble an enveloping worm with an enveloping type of worm gear. For many applications, only the modified worm gear 44 is enough.
• the enveloping worm gear 44 could connect to a drive shaft 46 for supporting the worm gear 44 from only one side or could be supported on both sides .
• the bodies of the enveloping worm gears 26 and 44 have axially extending end flanges that hook underneath flanges of adjacent collars to hold the worms in place.
• One or both of the worm and worm gear bodies are keyed or otherwise fastened to the shaft for driving or being driven. Relatively slight longitudinal movement of one or both the worm or worm gear allows for disassembling the entire worm gear - collars - shaft assembly.
• the ratio of the number of teeth 14 on the worm gear 16 relative to the number of threads 12 on the worm 10 is 11 to 1 and less. Most preferably, the ratio is three or even less, as shown. It is possible that only two teeth 14 need to be utilized on worm gear 16.
• the worm/worm gear transmission used in the present application could also self lock.
• the term "self-locking" as it is utilized in this application to describe the inventive worm and worm gear combinations means that the teeth of the worm gear, when in contact with the thread of the worm, are not capable of rotating the worm about the axis of the worm.
• the teeth 14 do not slip on the thread 12 causing the thread 12 to rotate about its own axis.
• the worm/worm gear transmission of the present invention particularly lends itself to a geometric as opposed to a purely frictional type self-locking device.
• Figure 9 shows a shortened enveloping worm 50 with an enveloping type of worm gear 52, which has a different profile of the teeth 53, compared to the teeth 28 of the worm gear 26 (shown in Figures 2 and 7) even for the same number of worm gear teeth. It is because this profile was generated by a shortened enveloping thread 54 for the shortened enveloping worm 50.
• enveloping worm 50 is connected to a drive shaft 56 which supports the worm 50 from one side.
• Figure 11 shows a view of a worm/worm gear transmission with the modified enveloping split worm 60 having two threads 61 in an off-center position relative to the enveloping-type worm gear 62 having six teeth 63.
• Figure 12 shows a side view of a worm/worm gear transmission with two modified worms 60 having two threads 61 in off-center positions and respectively connected to different drive shafts 62 and 64 and each meshingly engaged with the worm gear 62.
• Figure 13 shows a view of a worm/worm gear transmission with two modified worms 60 in off-center positions placed on the same axis of rotation and connected to the same drive shaft 32.
• FIG. 14 shows a view of a worm/worm gear transmission with two modified worms 60 having worm threads 68 each placed on different axes of rotation and connected to different drive shafts 70 and 72. Each of the worms 60 meshingly engage the worm gear 62 having teeth 64.
• Figure 15 shows a side view of an enveloping worm gear 62 with a different profile of teeth 64 generated by the enveloping thread 68 of worm 60 as shown in Figure 14.
• Figure 16 shows a view of a worm/worm gear transmission with two enveloping worms 22 having corresponding worm threads 24 placed on different axes of rotation and which are connected to drive shafts 32. Each of the worms 22 meshingly engage the enveloping worm gear
• Figure 19 is a perspective view of a worm/worm gear transmission including worm gear 80 having ten teeth 82 meshing with an enveloping split worm 84 including a thread 86.
• Figure 20 is a perspective view of a worm gear 90 having nine teeth 92 meshing with a modified enveloping split worm 94 with three threads 96.
• Figure 23 illustrates the size difference of a worm/worm gear transmission as shown in Figure 20 in comparison with the size of a typical hypoid gear 106.
• the motion could be provided from the drive shaft through enveloping worm 12 and enveloping-type worm gear 16 to an output shaft or back from the output shafts to the drive shaft 32.
• the same operation is applicable for motion from the drive shaft to the driven shafts or from the driven shafts to drive shaft of the other embodiments shown.
• motion can be provided only from the drive shaft through the enveloping worm and to the enveloping type worm gear and to the output shaft.
• the worm/worm gear transmissions shown in Figures 12, 14 and 16, with independent drive shafts connected to the worms could be used in a split-power transmission of a helicopter drive to transmit energy from a high-speed engine to a rotor drive shaft.
• the worm gear could be connected directly (or by gear train) to the helicopter rotor drive shaft, and worms could be connected to the output of the helicopter engine directly (or by gear train) .
• the worm/worm gear transmission of the present invention could replace bevel gears.
• the greater enveloping angle for one revolution of the worm thread permits the use of worm gear teeth without undercut portions .
• a worm and worm gear combination are utilized to transmit rotation with the smallest ratio between the worm gear teeth and one worm thread. In the past, it has been believed that at least 24 teeth were required for a worm gear to be used with a double enveloping worm/worm gear combination.
• the big difference from the traditional worm/worm gear is not only in the number of teeth, but also in the enveloping angle of the worm thread, which is used for generation of the profile for the worm gear teeth.
• This enveloping angle can be as large as 180 degrees for one revolution of the thread when the number of worm gear teeth is only 2 but is preferably larger than 15 degrees.
• a self-locking worm/worm gear combination can have a worm gear to worm thread ratio that is preferably 10 and less.
• each one of the worm and worm gear combinations described above can transmit very high torque loads when compared to prior systems .
• the worm and worm gears have been formed of materials having low coefficients of friction; worm gears typically were made only from bronze. With the present invention however, the worm and worm gear could be made from a strong material such as steel .
• the preferable shape of the teeth and threads for the worm gear and the worm is shown in the drawings, but could be different. Even so, a worker of ordinary skill in the art would recognize that other shapes would come within the scope of this invention.
• the present invention can replace hypoid or bevel gearing in many applications.
• the lower noise of the worm/worm gear transmission compared with hypoid and bevel gear transmissions make using the worm/worm gear transmission of the present invention more beneficial, in particular, in helicopter or car power train applications.
• this invention has more than twice the capacity of hypoid gearing, where the hypoid gear also has more than 24 teeth.
• the smaller number of teeth of the present invention than in a hypoid gear of the same circumference makes each tooth thicker and therefore stronger.
• a bodiless enveloping worm 200 is shown having threads 202 in meshing engagement with an enveloping worm gear 204.
• the threads 202 of the enveloping worm 200 are supported at opposite ends (202A, 202B) thereof by support members 206.
• the threads 202 can be integrally formed with the support members 206 by casting or machining, or can be welded to the support members 206 or attached by other known techniques.
• a full enveloping worm is provided with threads 202 connected to support members 206.
• Figure 49 illustrates an additional support disk 208 used for connecting between the threads 202 at an intermediate position between the two ends (202A, 202B) of the threads 202.
• the support disk 208 adds additional strength and rigidity to the threads 202.
• Figure 50 illustrates a bodiless split enveloping worm 212 having threads 214 connected to a base support member 216 and to an end support member 218.
• the bodiless split enveloping worm 212 is supported for rotation by the base support member 216.
• the bodiless enveloping worm designs as described above provide a flexible worm which is capable of absorbing torsional spikes to the worm/worm gear transmission.
• the bodiless enveloping worm designs lend themselves to improved lubrication along the entire length of the threads.
• the basic inventive system of the present invention can be reconfigured into many different mechanical transmissions. For example, it can be used in a front axle drive and differential drive rear axle of a car, power windows, escalator drive and more.
• the enveloping worm and worm gear as described above can be utilized in an apparatus for transmitting rotation utilizing an oscillating input as shown in Figure 24.
• the apparatus includes a worm 111 which is enclosed in a rotor 112.
• the rotor 112 forms a rigid support to mount bearings.
• the worm 111 is enveloping and wraps around worm gear 113.
• the worm gear 113 is also enveloping and wraps around the worm 111.
• the worm gear 113 rotates with low speed.
• the minimum ratio between the number of worm gear teeth and one worm thread provided on the worm 111 is two (2) .
• worm 111 rotates with higher speed.
• This invention comprises means for rotating the worm 111 about its axis of rotation relative to the worm gear 113.
• Said means can be the auxiliary motor or in a gear train comprising a hypoid-gear set, spiroid-gear set, bevel- gear set or helicon-gear set, may consist of gears 116, 117 with the on/off clutch 118.
• Input of the train is driven by the worm gear 113 from the input shaft 114 and the worm 111 is driven by the output (on/off clutch) of the train.
• the rotor 112 is connected to the output shaft 115.
• On/off clutch 118 can be a friction electromechanical clutch with natural conditions like "on” or “off” .
• the ratio of the train is more or equal to the ratio between the number of teeth on the worm gear 113 relative to the threads on worm 111.
• the worm 111 and worm gear 113 have the property of self-lock.
• FIG. 25 Examples of drive means for rotating the worm 111 about its axis of rotation relative to the worm gear 113 are shown in Figure 25 and Figure 26.
• the means as disclosed in Figure 25 is a gear train comprising spur gears 119, 120, flexible shaft 121 and the on/off clutch 118.
• the drive means as disclosed in Figure 26 is a pulley drive comprising pulleys 160, 161 with belt 162, the flexible shaft 161 and the on/off clutch 118.
• the drive means with flexible shaft 121 is easy to assemble in a single reduction unit. To provide a preload in a direction around an axis of the worm 111 and to eliminate a backlash between the teeth of the worm gear 113 and the thread of the worm 111, it is better to use an auxiliary motor.
• the differential gear set is a spider differential comprising sun gears 122, 123 with a spider gear 124, a housing 125 and a carrier 126 wherein the sun gear 122 is connected to the worm gear 113.
• the drive means is the auxiliary motor 127.
• the differential gear set is a spider differential comprising a sun gear 123, a ring gear 128 with a spider gear 130, a housing 125, and a carrier 126 wherein the sun gear 123 is connected to the worm gear 113.
• the differential gear set is a spider differential comprising a sun gear 123, a ring gear 128 with a spider gear 130, a housing 125, and a carrier 126 wherein the ring gear 128 is connected to the worm gear 113.
• the differential gear set is a spider differential comprising sun gears 122,
• the differential gear set is a spider differential comprising a sun gear 123, a ring gear 128 with a spider gear 130, a housing 125, and a carrier 126 wherein the carrier 126 is connected to the worm gear 113.
• the differential gear set is a bevel differential comprising bevel gears 129,
• the differential gear set is a bevel differential comprising bevel gears 129, 134 with an idler bevel gear 131, a housing 132 and a carrier 133 wherein carrier 133 is connected to the worm gear 113.
• the differential gear set is a bevel differential comprising bevel gears 129, 134 with a spider bevel gear 131, a housing 132 and a carrier 133 wherein the carrier 133 is connected to the worm gear 136.
• Bevel gear 134 is connected to the worm gear 113.
• An extra shaft 138 can provide an opposite direction of rotation.
• the drive means are auxiliary motors 127 and 137.
• a pair of worms 111 and 135 with the rotors 112 and 127, with each of the worm gears 113, 136 can be driven by independent shafts 114 and 115 and have a differential for connecting the worm gears with members of the differential .
• the differential gear set is a spider differential comprising sun gears 122,. 123, 128, with a spider gear 139, a housing 125 and a carrier 126 wherein the sun gear 128 is connected to the second worm gear 136, and the carrier 126 is connected to the first worm gear 113.
• the drive means are auxiliary motors 127 and 137.
• the differential gear set is a spider differential comprising sun gears 122, 123, and a ring gear 128, a housing 125, a spider gear 124 and a carrier 126 wherein the sun gear 123 is connected to the first worm gear 113 and the ring gear 128 is connected to the second worm gear 136.
• the drive means are auxiliary motors 127 and 137.
• the differential gear set is a spider differential comprising sun gears 122, 123, and a ring gear 128, a housing 125, a spider gear 124 and a carrier 126 wherein the carrier 126 is connected to the first worm gear 113 and the ring gear 128 is connected to the second worm gear 136.
• the drive means are auxiliary motors 127 and 137.
• the differential gear set is a spider differential comprising sun gears 122, 123, 128, with a spider gear 139, a housing 125 and a carrier 126 wherein the sun gear 128 is connected to the second worm gear 136 and the carrier 126 is connected to the first worm gear 113.
• the first drive means are gears 116 and 117 with on/off clutch 118 and the second drive means is auxiliary motor 127.
• the differential gear set is a spider differential comprising sun gears 122, 123, and a ring gear 128, a housing 125, a spider gear 124 and a carrier 126 wherein the carrier 126 is connected to the first worm gear 113 and the ring gear 128 is connected to the second worm gear 136.
• the first drive means are gears 116 and 117 with on/off clutch 118 and the second drive means is auxiliary motor 127.
• the differential gear set is a spider differential comprising sun gears 122, 123, and a ring gear 128, a housing 125, a spider gear 124 and a carrier 126 wherein the sun gear 123 is connected to the first worm gear 113 and the ring gear 128 is connected to the second worm gear 136.
• the first drive means are gears 116 and 117 with an on/off clutch 118 and the second drive means are gears 140, 141 with an on/off clutch 142.
• Figure 41 is a combination of Figure 24 and Figure 33.
• the differential gear set is a bevel differential comprising bevel gears 129 and 134 with an idler bevel gear 131, a housing 132 and a carrier 133 wherein the carrier 133 is connected to the worm gear 113 and to the worm gear 136.
• the rotor 112 is grounded .
• the differential gear set is a spider differential comprising sun gears 122, 123, a housing 125 with a carrier 126 and a bevel differential comprising bevel gears 129, 134 and an idler bevel gear 131, wherein the carrier 126 is connected to the first worm gear 113 and the sun gear 122 is connected to the second worm gear 136 and the carrier 133.
• the first drive means are gears 116 and 117 with an on/off clutch 118 and the second drive means is drive motor 127.
• Figure 43 discloses a split worm 143 enclosed in a rotor 144 and an auxiliary motor 145.
• the body of the rotor 144 holds removable balancing elements 146.
• Half or less than half of the worm 143 is easy to assemble with a worm gear 147.
• Figure 44 is a cross-sectional view of congruent surfaces of the lands on the half of the worm 143 and the teeth of the worm gear 147.
• Figure 45 is a cross-sectional view of the half worm 143 and the worm gear 147 with a train of a torsion spring 148 and with a friction clutch 149.
• Figure 46 is a cross-sectional view of two halves of worms 143 and 150 and the worm gear 147 with two trains including the torsion spring 148 with the friction clutch 149 and a torsion spring 151 with a friction clutch 152.
• the input shaft 114 drives worm gear 113.
• Output shaft 115 rotates with the rotor 112.
• a brush commutation connection could be utilized for the inventive purposes described in this application.
• a control system (not shown) interrupts power between the source of electricity and the auxiliary motor or the on/off clutch. For the on/off clutch application with normal condition "on”, the appearance of power changes the condition to "off".
• the clutch 118 has an "off" condition.
• Rotation of the shaft 114 in a positive direction with worm gear 113 rotating about its axis causes the worm 111 to rotate about the axis of worm gear 113 with rotor 112.
• This rotation is without relative movement between the worm 111 and worm gear 113. That is, the teeth of the worm gear 113 directly engage the thread on the worm 111, and there is no relative movement during this transmission.
• This rotation is provided by a normal force from the worm gear teeth against the thread on the worm. There is no relative movement, and thus the efficiency is maximum. This way, rotation of the output shaft 115 is achieved.
• clutch 118 has an "on" condition. Rotation of the shaft 114 also rotates gears 116, 117 and the worm 111. This rotation is provided such that the thread on the worm 111 avoids any forces from the teeth on worm gear 113, thus avoiding any transmission of rotation to the worm 111, and rotor 112. Even when the ratio of the gear train is more than the ratio of worm gear/worm, the clutch 118 permits sliding to prevent the gear train from crushing. Rotation from the input shaft 114 is not transferred to the output shaft 115.
• worm 111 as shown in Figures 25 and 26, rotates by transmission of rotation through flexible shaft 121.
• This design takes less space.
• the ratio between the worm 111 and worm gear 113 would require an auxiliary motor or gear train, turning the worm 111 to avoid interaction with the teeth on worm gear 113 that would be impractical when the input speed is very high.
• Most preferably, the ratio between worm and worm gear is less than 12. It is possible that only 2 teeth need to be utilized on the worm gear 113.
• the transmission of power from the worm gear 113 to the worm 111 occurs without relative movement and is typically the case with the worm and worm gear combination.
• the teeth of the worm gear 113 are brought into contact with the thread on the worm 111, and the worm gear 113 is prevented from rotation about its own axis.
• a force is applied to the worm gear 113 which drives the worm 111 about the axis of the worm gear 113, thus imparting rotation to the rotor 112.
• the material selected for the members is different than that which has been utilized in the past.
• the worm and worm gears have been formed of materials having low coefficients of friction and a lubricant is typically utilized. In this invention, lubricant would not be needed.
• the worm and worm gear are made from a strong material such as steel .
• the shape of the teeth and threads and the worm and worm gears are designed to achieve a self-lock feature.
• a material that actually increases the friction may be placed on the teeth and threads.
• the gear train or pulley drive with on/off clutch or auxiliary motor will be of a relatively low torque. Its function is to turn the worm without any interaction relative to the teeth of the worm gear and to stop under overload even when the worm is fixed by the worm gear. Thus, a high torque motor or on/off clutch need not be utilized. For that reason, only a low amount of electrical energy is required to operate the on/off clutch or auxiliary motor.
• Figure 27 and Figure 30 describe transmissions for transferring positive/negative rotation of the input shaft 114 with different torque or disconnecting the output shaft 115 from the input shaft 114.
• the ratio depends on the number of teeth in gears 122 and 123.
• Figures 28, 29 and 31 describe transmissions for changing the direction of rotation from the input shaft 114 with a different torque or disconnecting the output shaft 115 from the input shaft 114.
• the ratio depends on the number of teeth in gears 128 and 123.
• Figures 32 and 33 describe transmissions for changing the direction of rotation with the same torque or disconnecting the output shaft 115 from the input shaft 114.
• Figure 34 discloses a transmission for changing the direction of rotation from the shaft 114 to shafts 115 or 138 or disconnecting the output shaft 115 from the input shaft 114.
• the shaft 138 has the direction of rotation of the input shaft 114.
• worm gear 136 is held by worm 135, the shaft 115 has an opposite direction of rotation from the input shaft 114.
• Figures 35-40 disclose the designs of a transmission with a ratio of 1 (one) for connecting the input shaft
• Figures 35-37 are different from Figures 38-40 in the drive means used for rotating the worms 111 and 135.
• Figure 41 is a combination of the device of Figure 24 with the device of Figure 33. Only rotor 113 is grounded. In Figure 42 the rotors 113 and 133 are grounded. But this combination has other properties.
• the ratio between the input 114 and the output shaft 115 is 1 (one) .
• the ratio between the input 114 and the output shaft 115 is -1 (minus one) .
• FIG. 45 half or less than half of a split worm 143 can be provided with means which include a train of a torsion spring 148 with a friction clutch 149 where the worm 143 is attached to the torsion spring 148 and the friction clutch 149 is attached to a rotor 144.
• Torsion spring 148 helps to remove clearance between the thread of the worm 143 and the tooth of a worm gear 147 after each change in direction of rotation of the input shaft 114.
• Figure 46 shows that each of the worms 143 and 150 and the worm gear 147 combinations described above can transmit very high torque loads.
• the present invention is based on the principal of differential systems. These systems have three members: an input, an output, and a control member. Various combinations of connecting these members with the worm gear results in different performances and characteristics.
• Input power goes from the input to the output of the differential.
• the control member is normally stationary under internal reactions.
• an auxiliary motor unlocks the worm gear by rotating the worm in a direction with the internal reactions on the worm (not against the direction of the internal reactions) . Unlocking motion of the worm gear under load does not require much power, compared to power transmitted from the input to the output of the differential.
• the low ratio of the enveloping worm and worm gear do not require much power from the auxiliary motor.
• the new invention described above has some advantages. For transmitting oscillation motion, it provides the fast reverse of a movement of the output shaft by changing the direction of rotation by an auxiliary motor. It requires little or no lubrication between the working parts because a worm and a worm gear have relative motion only when the worm is unloaded and eliminated of backlash between the worm gear and the worm. For speed regulation in a variable speed transmission it allows lubrication between the working parts without losing self-locking (due to the self-locking geometry of the worm/worm gear transmission) that increases efficiency by reducing power to provide unlocking motion of the worm.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Gear Transmission (AREA)
• Gears, Cams (AREA)

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• 1999
  • 1999-10-15 EP EP99974125A patent/EP1222412A4/de not_active Withdrawn
  • 1999-10-15 KR KR1020027004840A patent/KR20020065483A/ko not_active Application Discontinuation
  • 1999-10-15 JP JP2001532007A patent/JP2003515064A/ja not_active Withdrawn
  • 1999-10-15 WO PCT/US1999/024199 patent/WO2001029449A1/en not_active Application Discontinuation
  • 1999-10-15 AU AU12080/00A patent/AU1208000A/en not_active Abandoned
  • 1999-10-15 CA CA002387678A patent/CA2387678A1/en not_active Abandoned

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