GB2185085A

GB2185085A - Axial drive mechanism

Info

Publication number: GB2185085A
Application number: GB08629733A
Authority: GB
Inventors: Joseph Pickles
Original assignee: Ferro Manufacturing Corp
Current assignee: Ferro Manufacturing Corp
Priority date: 1985-12-27
Filing date: 1986-12-12
Publication date: 1987-07-08
Also published as: DE3643613A1; JPS62188850A; GB2185085B; GB8629733D0

Abstract

An axial drive mechanism consisting of a worm gear 16, a first planetary gear system 20 having a carrier 22, helical planet gears 32 in meshing engagement with the worm gear 16 and mounted on the carrier, and a ring gear 38 on the carrier. An electric motor 12 can be used to drive the worm gear and a second planetary gear system 40 can be arranged in a coaxial relation with the first system to achieve a desired gear reduction while retaining the axial arrangement of the drive. The second planetary gear system 40 has planet spur gears 42 arranged about and in meshing engagement with the first ring gear 38 and a stationary ring gear 48 encircling the planet spur gears. The second planetary gear system includes a carrier 46 on which the planet spur gears are mounted and an output pinion gear 50 formed integral with the last mentioned carrier. The stationary ring gear is conveniently formed as part of the housing for the electric motor. <IMAGE>

Description

SPECIFICATION Axial drive mechanism Backgroundandsummary of the invention This invention relates generally to drive mechanisms and more particularlyto an axial drive mechanism that has the advantage of being compact and can thus be used in installations, such as adjustable seat mechanisms, where space availabilities limit the size and shape of the drive mechanism that can be used. The drive mechanism is conveniently driven by an electric motor with a coaxial drive shaft but it can also be driven buy a remote drive.

The axial drive assembly ofthis invention includes a worm gear, a planetary gear system having a carrier, helical planet gears mounted in inclinedposi- tionsonthecarrierin meshing engagementwiththe worm gear, and a ring gearwhich is formed integral with the carrier, the planetary gear system being in a coaxial relation with the worm gear. The ring gear can then be used to drive a variety of other mechanisms.

A second planetary gear system having planet spur gears arranged about and in meshing engagementwith the first ring gearcan be disposed in axial alignmentwith the first planetary gear system to obtain a further gear reduction. The second planetary gear system includes a stationary ring gearwhich encircles the planet spur gears and is integrally formed with the housing forthe drive assembly. The second planetary gear system also includes a carrier on which the planet spur gears are mounted and an output pinion gearthat is formed integral with the last mentioned carrier.

The drive shaft, worm gear, carriers and ring gears are in substantial axial alignmentto thereby confine the transverse dimension of the drive assembly. In one embodiment of the invention, this dimension is substantiallythesamedimension asthetransverse dimension of an electric motor used to drive the worm gear.

It can thus be seen that in the drive mechanism of this invention, the two planetary gear systems are structured and arranged so that they are coaxial with each other and with the worm gearand operateto provide an outputwhich is of reduced speed and of increased torque relative to the output from the electric motor drive shaft. Such a drive assembly has applicability to numerous mechanical environments wherein components must be selectively moved.

Further objects, features and advantages of the invention will become apparent from a consideration of the following description and the appended claims when taken in connection with the accompanying drawing in which: Figure lisa fragmentary longitudinal sectional view of one embodiment of the axial drive mech anismofthisinvention in which the worm gear is driven by a coaxially arranged drive shaft with some parts broken away and other parts shown in section forthe purpose of clarity; Figure 2 is a bottom view of the assembly shown in Figure 1, on a reduced scale, showing a driven member in assembly relation with the output gear in the mechanism;; Figure 3 is an exploded perspective view of the axial drive mechanism of this invention shown in Figure 1, with the housing therefor removed forthe purpose of clarity; Figure 4 is a fragmentary side elevational view of the axial drive mechanism ofthis invention shown in Figure 1, shown mounted on a support rail and as part of a two motor drive assembly; Figure 5 is a longitudinal sectional view of another embodiment ofthe drive mechanism ofthis inven- tion; and Figure 6is a side elevational view, like Figure4 of a three motor drive assembly embodying the drive mechanism ofthis invention.

With reference to the drawing, the axial drive mechanism of this invention, indicated generally at 10, is shown in Figures 1 and 5 as including a worm gear 16having an axis 15 and a planetarygear system 20. The planetary gear system 20 is positioned in a driven relation with the worm gear 16 and includes a carrier 22 of irregularshape. The carrier 22 has a central cavity 24 and is positioned so that the worm gear 16 extends into the cavity 24.

An annulargearsupportsection 28 surrounds the cavity 24 and encircles the worm gear 16. This gear support section 28 includes a plurality ofsupport surfaces 30 (Figure 3), shown as three in number, which are inclined at an angle of substantially 45"to the axis 15 of the worm gear 16. A plurality of helical planet gears 32, shown as three in number, are mounted onthesupport surfaces 30 as shown in Figure 3 so that the teeth on the gears 32 will mesh with the teeth on the worm gear 16.

Each of the gears 32 rotatesaboutashaft34car- ried by the carrier 22 and located sothatthe gear32 can be positioned substantiallyflatagainstthe inclined surface 30. As a result, the gears 32 are likewise inclined atan angle of about 45" to the axis 15.

The carrier 22 has an extension 36 which extends axially away from the cavity 24 and is provided with integral teeth forming a ring gear38.

An electric motor 12 having an axial drive shaft 14 formed integral with the worm gear 16 is shown in Figure 1 for driving the worm gear 16 about the axis 15. Axially beyond the worm gear 16, the driveshaft 14terminates in a thrust or bearing portion 18which engages the bottom wall 26 of the carrier cavity 24.

Asecond planetary gear system 40 is shown in Figure 1 axially aligned with the worm gear 16 and the axial drive mechanism 10. The system 40 has a plurality of spur gears 42 arranged about and in meshing engagementwiththe ring gear 38 in the planetary system 20. The spur gears 42 rotate about shafts 44 mounted on a carrier46 (Figure 3). Astati- onaryring gear48 is formed as an integral part ofthe housing 52forthe mechanism 10 and is in meshing engagement with the teeth on the spur gears 44. An output pinion gear 50 is formed integral with the carrier 46 and is located in a coaxial relation with the shaft 14.

Figure 5 illustrates an embodiment of the invention in which the axial drive mechanism 10 is mounted in a housing 70 and the ring gear38 is in a driving relation with a gear 72 that drives a shaft 74. The worm gear 16 is bearing supported on the carrier 22 and the housing 70 and is connected through a coupling 76 to a remote power source such as a motor (not shown). A bottom plate78 on the housing 70 carries a spindle 80 that extends into a central bore 54 in the ring gear38 and rotatablysupportsthecar- rier 22.

From the above description, it is seen that this invention provides an axial drive mechanism 10 which includes a worm gear 16 and an axially aligned planetary gear system 20. In the embodiment shown in Figures 1-4, a second planetarygearsystem 40 is in- terconnected and arranged in a driven relation with the planetary 20 so that the high speed, lowtorque output of the shaft 14 is translated into a low speed, hightorqueoutputofthepinion gearSO. The drive torqueoftheworm gear 16 providestheforcethat moves the pinion gear 50 and the stationary ring gear 48 provides the reaction force from which the driveforceforthe pinion gear 50 is generated.

As shown in Figure 1 ,the drive mechanism 10 is of a compact size and of a small dimension in a direction transversely of the motor drive shaft 14so that the transverse dimension of the mechanism 10 does not substantially exceed the transverse dimension of the motor 12. This enables use of the drive mechanism 10 in mechanical environments in which space is limited.

In the assembly 55 illustrated in Figure 4 utilizing drive mechanisms 10, a pairofmotors 12 arearranged side-by-side in a common housing 52a and the drive mechanisms are supported on a rail 56. Mounting members 58 are mounted at their lower ends on the rail 56 and at their upperends have support spindles 80 that are telescoped into the central bore 54in the ring gear36 and a coaxial bore 60 in the output pinion gear 50. The connectors 58 thus con stitute supports forthe axial drive mechanisms 10.

As shown in Figures2 and4, a geared lever62can be mounted on a support 64 on the rail 56 so that itis in meshing engagement with the output pinion 50 for driving the lever 52 back and forth about its pivot 64. Similarly, the pinion gear 50 on the adjacentdrive mechanism 10 can be arranged in a driving relation with a toothed member such as shown at 66.

The drive mechanism 10 is particularly applicable to adjustable seat assemblies in vehicles and an em bodimentoftheinventioh is shown in Figure 6for this use and indicated generally at 80. The assembly 80 is like the assembly 55 in that it includes a plurality of electric motors 12 in a common housing 52b.Two ofthe motors 12 drive axial drive mechanisms 10 that are associated with planetary systems 40 that drive pinion gears 50 and the third drive mechanism 10 drives a gear system 81 that drives a pinion gear 82 on a shaft 84 mounted in a bearing support 86.

The shaft84 in turn drives an outputgear88.

In the assembly 80, two of the mechanisms 10 are used to adjustthe seat in up and down directions and the third mechanism 10 is used to move the seat for ward and back.

During operation of the mechanism 10, the rotating worm gear 16 drives the helical gears 32 so asto rotate the carrier 22 aboutthe axis 15. Rotation ofthe carrier 22 results in rotation ofthe ring gear38which can be used to drive many different mechanisms.

The ring gear 38 is used in Figure 1 to drive the spur gears 42 which mesh with the stationary ring gear48 to in turn drive the carrier 46 and rotatethe output pinion gear 50 at a reduced speed relative to the speed of rotation of the drive shaft 14. The result is a compact axial drive mechanism which efficiently translates the high speed, low to rque rotation ofthe electric motor shaft 14 into a low speed, high torque rotation of the output pinion gear 50 which can be effectively utilized in a variety of mechanism installations.

Claims

1. In a drive mechanism which includes an electric motor having an output shaft, force transmitting structure comprising a worm gear in a driven rela tionwith said output shaft, a plurality of helical planet gears arranged in a meshed relation with said worm gear, each of said helical gears having an axis of rotation inclined with respect to the axis of said drive shaft atan angle of less than 90 , a first carrier arranged in coaxial relation with said shaft and in a supporting relation with said helical planet gears, a ring gearfixed on said carrier in a coaxial relation therewith, a plurality of planet spur gears positioned around and in a meshed relation with said ring gear, a second carrierforsaid planetspurgears and an output pinion gear fixed on said carrier and arranged in a coaxial relation with said coaxially arranged driveshaftand first carrier, a ring gearforsaid planet spur gears, and a housing forsaiqassembly,said last mentioned ring gear being formed as a part of said housing and having radially inwardly directed teeth in meshing engagement with said planet spur gearteeth.

2. A drive mechanism according to claim 1 wherein said helical gear axis of rotation-is inclined at an angle of substantially forty-five degrees to the axis of said drive shaft.

3. In an axial drive assembly, a worm gear having an axis and being adapted to be rotated about said axis, a first planetary gear system having a carrier, helical planet gears on said carrier in meshing engagementwith said worm gear, and a ring gear, a secondary planetary gear system having planet spur gears arranged aboutand in meshing engagement with saidfirst ring gearand a stationaryring ring gear encircling said planet spur gears, said second plane tarygearsystem including a carrier on which said planetspurgearsare mounted, and an output pinion gear formed integral with said last mentioned carrier, said planetary gear systems being coaxially arranged with said worm gear.

4. The axial drive assembly according to claim 3 wherein said first carrier is of an irregular shape having an annular support portion onwhich said helical planet gears are mounted and a central recessed portion which extends in a direction axially away from said drive shaft and terminates in an axial supportfor said first ring gear.

5. In a drive mechanism which includes an electric motor having an output drive shaft, forcetrans- mitting structure comprising a worm gear in a driven relation with said output shaft, a plurality of helical planet gears arranged in a meshed relation with said worm gear, each of said helical gears having an axis of rotation inclined with respect to the axis of said drive shaft at an angle of substantially 45", a first carrier arranged in a coaxial relation with said shaft and in a supporting relation with said helical planet gears, a ring gear fixed on said carrier in a coaxial relation therewith, a plurality of planetspurgears positioned around and in a meshed relation with said ring gear, a second carrierforsaid planet spur gears and an output pinion gearfixed on said carrier and arranged in a coaxial relation with said coaxially arranged drive shaft and first carrier, and a stationary ring gearforsaid planetspurgears.

6. Axial drive mechanism comprising aworm gear having an axis and adapted to be driven about said axis, a planetary gear system having an axis that isthesame as said gear axis, said system comprising a plurality of helical planet gears arranged in a meshed relation with said worm gear, each of said helical gears having an axis of rotation inclined with respecttothe axis of said drive shaft atan angle of less than 90 , a carrier arranged in coaxial relation with said shaft and in a supporting relation with said helical planet gears, and a ring gearfixed on said carrier in a coaxial relation therewith.

7. A drive mechanism according to claim 6 wherein said helical gear axis of rotation is inclined at an angle of substantially forty-five degrees tothe axis of said drive shaft.

8. Axial drive mechanism comprising aworm gear, a plurality of helical planet gears arranged in a meshed relation with said worm gear, each of said helical gears having an axis of rotation inclined with respect to the axis of said drive shaft at an angle of substantially 45 , a carrier arranged in a coaxial relation with said worm gear and in a supporting relation with said helical planet gears, and a ring gearfixed on said carrier in a coaxial relation therewith, said carrier being of an irregular shape having an annular support portion on which said helical planet gears are mounted and a central recessed portion which extends in a direction axially away from said drive shaft and provides axial supportforsaid worm gear.

9. An axial drive mechanism constructed and arranged to operate substantially as herein before described with reference to and as illustrated in the accompanying drawings.