GB2126292A

GB2126292A - Speed changing gearing

Info

Publication number: GB2126292A
Application number: GB08323217A
Authority: GB
Inventors: Richard L Meredith
Original assignee: Reliance Electric Co
Current assignee: Reliance Electric Co
Priority date: 1982-09-07
Filing date: 1983-08-30
Publication date: 1984-03-21
Also published as: AU552238B2; BR8304758A; AU1840883A; GB8323217D0; GB2126292B; ZA836418B; CA1204001A; FR2532707A1; FR2532707B1; DE3330147C2; DE3330147A1

Abstract

A speed changing device has a first section (22) consisting of a parallel axis gear set and a second section (24) of a planetary gear set, the two sets being in series, with the parallel gear set connected to the input shaft (14) and the planetary gear set to the output shaft (16). A brake assembly (90), consisting of a plurality of alternately arranged reaction and opposing annularly shaped plates controls the rotation of the ring gear (60) and hence the speed and torque of the output shaft (16). The brake plates are cooled and lubricated to assembly to control the speed of the output shaft (16) and to provide a soft start to accelerating the equipment (for example, a conveyor) driven by the speed changing device. The faces of the brake plates contain radially extending intersecting grooves forming a series of diamond shaped lands throughout the faces of the plates, and the grooves supply a cooling and lubricating fluid to the plate faces to facilitate optimum performance of the brake assembly over extended periods of time. <IMAGE>

Description

SPECIFICATION Speed changing device This invention relates to speed changing devices.

Generally in industrial applications, conventional gear reducers are of the single speed type consisting essentially of an input shaft on one side, an output shaft on the other side, and a fixed housing containing reduction gears interconnecting the two shafts. The housing, which encloses and supports the gearing between the shafts, is normally secured to a rigid base and forms the reaction memberforthetorque transmitted between the two shafts. Multiple speed powertransmissions, which often include gear reducers, are extensively used in the vehicular field, and are specially designed and constructed for that particular application.They are frequently of the gear shifttype, either manual orautomatic; however, clutch operation reaction types have been extensively used in the vehicularfield to vary the ratio between the engine and drive shaft. The foregoing vehiculartypes of speed changing mechanisms have not been utilized on most instances in industrial installation, primarily because they are unduly complex, large and expensive, and/or are unreliableforextended periods of operation for driving machinery and other equipment under heavy loads. Instead, variable speed changing involving gear reducers has principally been accomplished in the industrial field by using variable speed electric motors to drive the equipmentthrough single gear ratio reducers.

It is sometimes necessary or desirable to control variable speed reducers and other mechanical power transmission drives in response to the load on the driven equipment, and to vary the acceleration and deceleration rates of the drive even though the drive normally operates at a constant speed when in full operation. An example of thins type of application and operation is in drives for belt conveyors used for handling heavy materials such as ore, coal, rock and similar material. This type of conveyor equipment is often driven byan electric motorthrough a speed reducer connected to the shaft of one of the pulleys on which the conveyor belt is trained. The motor and speed reducer may be installed at the end ofthe driven pulley, orthe motor may be installed at the end ofthe pulley with the speed reducer mounted in the driven pulley as an integral installation.In the lattertype of installation, the motor drives the speed reducer through a shaft axially disposed i n the mai n pulley shaft, and the speed reducer reacts directly on the pulley to provide the drive torque therefor.

In belt conveyors, sudden starts with no load or only light loads may result in damage to the conveyor system or cause the conveyor belt to loosen to the extent that the conveyor fails to operate or operates inefficiently. Variable acceleration of a speed reducer has been effectively accomplished buy a brake mechanism used in conjunction with the reaction shaft of the speed reducer operating the driven pulley ofthe conveyor system. Such mechanisms and installations are disclosed and claimed in U.S. Patents Nos.

4,047,452 to Eddy, 4,168,611 to Woyton and Meredith, 4,189,962 to Chung, and 4,281,565 to Lower. While these patents disclose drives intended for conveyor systems and the like, these controlled start speed changing devices have a much more general field of use and broader applications, and may be used in a wide variety of installations.In the soft start concept of the foregoing patents, the power drive is responsive to the load on the power output element at the time of starting to provide the required torque and effect a soft start, and thereafter controls the acceleration rate until theconveyorsystem has reached normal operating speed, regardless ofthe load on the system, thus avoiding a quick start, normally involving a sudden jerk when the system is unloaded or has only a light load. This soft start concept has a distinct advantage in the operation of various types of equipment other than belt conveyors. It is also sometimes desirable to operate the equipment at slower than normal speed.

In the pastthis could not be accomplished using the braking mechanism, since the friction created sufficient heatto destroy the braking mechanism in a relatively short period oftime, and long soft start and acceleration periods could create sufficient heatto seriously damage the mechanism.

One of the principal objects ofthe present invention is to provide a speed changing device having an acceleration and deceleration control system which is highly reliable and efficient, and which can be operated for prolonged periods oftime under adverse conditions and/or at less than full speed, without attention or adjustment by an operator once the desired rate of acceleration and deceleration and/or speed has been selected forthe various operating parameters, and without subjecting the deviceto conditionswhichwould be likelyto cause serious damage to the device or equipment driven thereby.

Afurtherobjectoftheinvention isto provide a system for controlling the acceleration and deceleration rateofa mechanical power drive which normally operates at a substantially constant speed, and which may be driven by a constant speed motor and yet be capable of providing a soft start and slow acceleration ofthe equipment with any gear ratio selected.

Still another object is to provide a dual type speed changing device which is relatively simple in operation and construction, which can be installed and operated under adverse environmental and operating conditions, and which is capable of easily being modified by changing a pinion and gear combination to adapt itto different applications and types of installations.

The foregoing objects, and other objects and advantages which wi li become apparent from the following description of the present invention, are accomplished buy a speed changing device having a planetary gear reducer, the reaction element of which is controlled by an oil cooled reaction brake, normally responsive to the load on the equipment being started and driven by the speed changing device. The reaction brake is ofthe multiple disc type, actuated by a hydraulic piston, andthe cooling fluid isforced under pressure between the discs which preferably have surfaces with a special configuration to provide optimum flow of fluid between the discs.The discs of the actuating brake are, in effect, in a floating arrangementwiththe ring gearandthereaction member on the housing to permit effective centering of the various parts without interference of the brake discs. The fluid may be forced between the discs throughout the operation of the speed changing device, and the cooling and lubricating effect of the fluid wili permitsome slippageto vary or regulatethe output speed ofthe device to something less than maximum speed. The reaction brake is preferably disposed on the output side of the reducer and reacts between the ring gear and the housing.One ofthe features ofthe concept disclosed in the application is the combination of a single stage, parallel axis gear reducersection involving a pinion and gear, with the pinion preferably on the input shaft, and the planetary reducer section on the output side ofthe device. In the event a change in the gear ratio is desired, the pinion and the driven gearofthe gear section can be relatively easily changed without disassembling the more complicated planetary gear section. This dual section can be reversed so that the planetary gear section is on the input side ofthe speed changing device and the parallel axis, gear reducing section is on the output side. In either of these two arrangements, the selection ofthe desired gear reduction can be made by changing the pinion and driven gear reducer section.

Figure lisa perspective view of the speed changing device embodying the present invention; Figure 2 is a horizontal cross-sectional view taken on horizontal line 2 of Figure 1; Figure 3 is an enlargedfragmentarycross-sectional view ofthe speed changing device, the view being indicated on Figure 2 by the broken circle identified by the numeral 3; Figure 4 is a perspective view of a brake element used in the present device; Figure 5 is an exploded view of a portion ofthe planetarygearsection and reaction element used in the present speed changing device; and Figure 6 is an enlarged fragmentary view of one of the plates ofthe disc pack ofthe reaction brake used in the present speed changing device.

Referring more specifically to the drawings, and to Figures 1 and 2 in particular, numeral 10 indicates generally a speed changing device embodying the present invention, having a housing 12, an input shaft 14 and an output shaft 1 journaled in the opposite side walls 18 and 20 ofthe housing. Inthe embodiment illustrated in the drawings, the present speed changing device has two basic sections consisting of a parallel axis gear reduction section indicated generally by numeral 22, and a planetary gearsection indicated generally by numeral 24. These two sections interconnect the input shaft 14 and the output shaft 16.

Arrangements ofthesetwo sections other than that shown in the drawings may be used if desired.

The gear section 22 consists of input shaft 14 journaled in bearings 30 and 32 supported by external sidewall 18 ofthe housing 12, and an innerwall 34 in the housing. A pinion 36 is disposed on orformed integrally with input shaft 14 and meshes with a gear 38 mounted on a shaft 40 and keyed thereto for rotation therewith, the shaft 40 being journaled in bearings 42 in sidewall 18 and bearing 44 in innerwall 34.The pinion 36 and gear38are lubricated bythe lubricant in the lower portion ofthe housing in which gear 38 is partially submerged. Different reductions in speed can be selected by varying the ratio between pinion 36 and gear 38. Since these two parts can be relatively easily changed, the desired speed reduction can conveniently be varied from one installation to anotherto satisfy requirements.

The planetary reduction section 24 consists of sun gear 62 and three planetary gears 64,66 and 68 having shafts journaled in the planetary gear carrier, indicated generally by the numeral 70, having flanges 72 and 74 in which the shafts of the planetary gears are journaled and an extension 75journaled in bearing 76 supported by an annular extension on internal wall 34.

The sun gear 62 and shaft 40 are interconnected by a spline coupling 78 in extension 75so that sun gear 62 and shaft40 rotatetogetherand relative to the planetary gear carrier. Hence, rotation of shaft 40 and sun gear 62 rotates the three planetary gears in ring gear 60 as in a conventional planetary gear reducer.

Each ofthree planetary gears 64,66 and 68 is mounted on a shaft 80 seated in holes in flanges 72 and 74, and bearings 82 and 84 are disposed on the shaft and the respective planetary gears are journaled on the two bearings for relative rotation with respect to shaft 80.

The planetary gear is controiled by a reaction brake, indicated generally by the numeral 90, having a plurality of interleaved friction plates 92 connected to annular housing insert 94 by spline part 95 and opposing plates 96 connected to extension 98 of ring gear 60 by spline part 99. Plates 92 are prevented from rotation by the spline formed by interlocking ribs and grooves on the plates and on the periphery of annular member 94, and plates 96 are prevented from relative rotation with respectto oneanotherbythespline formed by interlocking ribs and grooves on the opposing plates and on the internal surface of extension 98 of ring gear 60; thus, the friction and opposing plates move relativeto one another during operation ofthe planetary gear section until the brake is fully applied. The braking is achieved by ring shaped piston 100 disposed in a ring shaped cylinder 102, the latter being connected to a hydraulic control pressure source through port 104, the piston being sealed at the cylinder walls by O-ring gaskets 106 and 108 in the side wall ofthe cylinder.When hydraulic fluid is admitted into cylinder 102, the piston 100 moves laterally to the left,thereby compressing the friction and opposing platestogetherto create a resistance to the rotation of the ring gear 60, thus causing the planetary gears ot rotate relative thereto and to rotate carrier 70 to which output shaft 16, journaled in bearing 109, is joined integrally. One of the important features of the present speed changing device is the use of a reaction brake which is lubricated and cooled by fluid forced under pressure between the plates. The fluid is admitted into an annularchannel 110 in the external surface of member 94 under pressure through port 112 and flows outwardly between the friction and opposing brake plates, where it lubricates and cools the plates while they are under compression from piston 100. As the pressure is applied by piston 1 00to the stack of plates, the friction or drag produced thereby on the ring gear produces the desired gear reduction accomplished by the planetary section. Most brake systems under the operating conditions to which the present speed changing device is subjected will become excessively hot if operated for any extended period of time.Consequently, brake systems in planetary reducers have not permitted prolonged or indefinite operation as a means of accomplishing desired speed reduction and/or prolonged soft start operations. The present system has overcome this difficulty by the utilization of a particu larsurface configuration on the two sides of the friction plates. This surface construction and configuration are illustrated in Figure 6, and consist of a plurality of generally radially disposed, though somewhat diagonal, grooves 120 and 122 extending from the internal edge to the external edge of the plates.

The grooves which form diamond shaped lands 124 throughoutthe opposite side surfaces ofthe plates, and permit the oil to flow continually th rough grooves 120 and 122from annulargroove 110tothe external surface ofthe brake plates, and the configuration formed thereby, permit the plates to be lubricated relativetooneanotherto reducefriction and to maintain asatisfactoryoperatingtemperatureinthe stack of plates so that the brake can be operated an indefinite period oftime at any preselected speed. The pressure on the plates can be varied infinitely between virtually no drag orfriction tofully engaged plates, where the stack of plates and the ring gear are stationary, to obtain an infinitely variable speed reduction in the planetary section.The piston 100 is returned to its withdrawn position by a plurality of springs 130 mounted on pins 132, each spring reacting againstatab 134 on each pin and forcing thetabto the right, as viewed in Figures 2 and 3, to return piston 100 to its withdrawn position, thereby permitting the friction and opposing plates to separate.

The lubricating and cooling fluid flows inwardly through holes 112 into annular space 1 10 and thence axially in the longitudinal grooves of splined part 95 into which the inner edges ofthefriction plates are disposed. The pins and springs are seated in grooves 136 and extend into holes in ring 138 secured to the inner end of member 90. The brake assembly is held in operative position in the ring by member 140 secu red to member 138 by a plurality of bolts 142, the member 140 extending into and loosely seating in a slot 144, forming a structural arrangement which permits a floating relationship between the brake assembly and the ring gearto permitthe ring gearto center itself in the final assembly.

Alubrication pumpiSOforthe bearings is mounted on inner wall 34 and connected to and driven by input shaft 14. Oil is pumped from the sump in the bottom of the housing through various channels, most ofwhich are not shown, to the bearings for the shafts.

In the operation of the present speed changing device, a motor is connected to input shaft 14,and a drive sprocket, coupling, gear, or pulley is mounted on output shaft 16 for connection to the equipment to be driven by the device. As shaft 14 is driven, it rotates pinion 36, which in turn rotates gear 38 and shaft 40.

Since shaft 40 is connected by coupling 78 to sun gear 62, the planetary gears 64,66 and 68 and ring gear 60 are rotated at substantially the same rate asshaft40, before the reaction brake has been applied, and the planetary gear carrier remains stationary. To obtain the desired speed from the gear section 22 to the output shaft 16, the reaction brake 90 is applied by the introduction of hydraulic fluid into cylinder 102, which forces the ring piston 100 against the brake plates, therebyforcingthe brake plates into partial orfull contactwith one another. This either slows or stops the rotation of ring gear 60, the amount of decrease in speed achieved depending upon the pressure applied by the brake piston.As the speed of rotation ofthe ring gear is reduced, the speed of rotation from the gear section 22 to the output shaft 16 is increased, and the maximum speed is reached when the ring gear is fully stopped by the application of reaction brake 90.

In many installations, a speed between thefull speed of gear section 22 and the full reduction obtained by zero rotation of ring gear 60 may be desired. In order to obtain this, the brake 90 is applied with a preselected pressure, which permits the opposing plates to rotate relative to the friction plates, thereby permitting the ring gearto rotate, but at a reduced speed. This type of operation is particularly effective for obtaining a soft startfor driving conveyors and other equipment where a rapid start-up would result in a shock to the equipment, which might cause serious and irreparable damage to the equipment. The equipment is accelerated by the application offurtherforce of the brake, which causes a still slower rotation of ring gear 60 until the desired speed is reached.

If it is less than the full zero rotation of the ring gear, the opposing plates continue to rotate relative to the friction plateswhilethe cooling fluid is applied through port 112 into annular passage 110, and thence to the grooves of part 95 forming a splined rela tionshipwiththe inner edges ofthefriction plates 92.

The cooling fluid then flows outwardly between the plates th rough grooves 122 and 124 and is discharged from the outer ends ofthe grooves from where it drips into the sump ofthe housing. The continual flow of fluid through the grooves prevents the plates from increasing intemperatureto the point where damage occurs, and hence permits the continual use of the gear reducer at any chosen speed up to full speed reduction achieved bythe planetarygearsectionwith the zero rotation ofthe ring gear.When the brake is released, pressure ofthefluid delivered to cylinder 102 is decreased and springs 130 reacting against tabs 134On pins 132 release the packoffriction and opposing plates so that the opposing plates can rotate freely relative to the friction plates, and the ring gear is free to rotate without interference from the brake.

It is seen from the foregoing, that the present speed changing device provides a variable speed output covering a broad range of selected speeds by the output shaft while the speed changing device can be driven by a constant speed motor. Regardless of whether or not the device is used for a preselected constant speed, it can effectively be used for a soft start operation which permits slow acceleration to avoid shock on the driven equipment. The range of applications ofthe device can be extended by changing the gear ratio in the parallel axis gear section, and this change can be made without any major or difficuitoperation being required to make the changes. Further, while the device is shown with the parallel axis gear section on the input side and the planetary section on the output side, the two sections can be reversed if desired, so thatthe planetary section would be on the input side of the device and the parallel axis gear reducer would be on the output side of the device.

While only one embodiment of the present speed changing device has been described herein in detail, various changes and modifications can be made without departing from the scope of the invention.

Claims

1. A speed changing device comprising: a housing; a main input shaft and a main outputshaft; a parallel axis gear section disposed in said housing and having a rotatable output element and a pinion connected to and rotatable with said main input shaft; and a planetary gear section disposed in said housing and having asun gearconnectedtotherotatable output element of said parallel axis gear section; a plurality of planetary gears having a carrier connected to said main output shaft; a ring gearsurrounding said planetarygearsand meshing therewith; and a reaction brake connected to said housing and to said ring gear for controlling the speed and torque of said main output shaft.

2. A speed changing device as defined in Claim 1 in which said reaction brake includes a plurality of annularfriction and opposing plates alternately arranged in side-by-side relationship, means connect ing said friction plates to said housing in a nonrotat able position, means connecting said opposing plates to said ring gear, and a hydraulically operated piston for actuating said brake by urging said friction and opposing plates toward one another.

3. A speed changing device as defined in Claim 2 in which channels are provided in said means connecting the friction plates to the housing for cooling and lubricating fluid for said plates, said grooves being disposed adjacent the inner edges of said plates and connected to the interfaces thereof.

4. A speed changing device as defined in Claim 3 in which the faces of said friction and opposing plates contain grooves extending generally radially outwardly and intersecting one another to form a generally diamond shaped land configuration throughout the faces of the friction and opposing plates.

5. A speed changing device as defined in Claim 1 in which said reaction brake includes annularly shaped friction and opposing plates alternately arranged in side-by-side relationship, with the friction plates connected to the housing and the opposing plates connected to the ring gear, and a hydraulic piston urges said plates toward one anotherto restrain the rotation of said ring gear.

6. Aspeed changing device as defined in Claim 5 in which a channel adjacent the inner edges of said friction and opposing plates supplies cooling and lubricating fluid to said plates, and generally radially extending grooves are provided in the faces of said platesforfacilitating the flow of said fluid between said discs.

7. Aspeed changing device as defined in Claim 6 in which said grooves in the faces of each of said plates intersect one another and form a generally diamond shaped land configuration throughoutthe surfaces of said discs.

8. Aspeedchanging devicecomprising; a first speed changing section; an input shaft connected to said section; a second speed changing section connected to said first speed changing section; an output shaft connectedto said second speed changing section, one of said sections being a parallel axis gear set and the other speed changing section being a planetary gear set.

9. A speed changing device as defined in Claim 8 in which said first speed changing gearset consists of a parallel axisgearset.

10. A speed changing device as defined in Claim 9 in which said second speed changing section consists of a planetary gear set connected to said first speed changing section and to said output shafts.

11. A speed changing device as defined in Claim 10 in which said planetary gear set includes a ring gear and a reaction brake connected to said ring gear and consisting of a plurality of annularly shaped friction and opposing plates alternately arranged inside-by- side relationship, and a fluid actuated piston for urging said plates toward one anotherto control the speed of said ring gear.

12. In a speed changing device: a planetary gear reducer having a ring gear and a reaction brake assembly including: a plurality of annularly shaped friction and opposing plates alternately arranged in a side-by-side reiationship, said friction plates being held in a nonrotatable position; and said opposing plates being rotatable and connected to said ring gear; channels for cooling and lubricating fluid for said plates disposed adjacentthe inneredgesofsaid plates and connected to the interfaces thereof; and grooves in the faces of said plates extending to the outer edges of said plates.

13. In a speed changing device, a planetary gear reducer as defined in Claim 12 in which a fluid actuated cylinder urges said friction and opposing plates toward one another to control the rotation of the ring gear, thereby controlling the speed and torque ofthe output shaft.

14. In a speed changing device, a planetary gear reducer as defined in Claim 12 in which the grooves in the faces of said plates intersect one another in each of the faces and form a diamond shaped land configuration throughoutthefaces ofthe plates.

15. In a speed changing device, a planetary gear reducer as defined in Claim 13 in which the grooves in the faces of said plates intersect one another in each of the faces and form a diamond shaped land configuration throughoutthefaces ofthe plates.

16. Inaspeedchanging device,a planetary gear reducer as defined in Claim 12 in which said ring gear has a lateral extension thereon and a spline-like means interconnects said opposing plates and said ring gear extension with one another for rotation in unison.

17. In a speed changing device, a planetary gear reducer as defined in Claim 12 in which the interlocking parts of said spline-like means fit relatively ioosely with respect to one another to permitthe brake assembly and ring gear to adjust effectively to one another.

18. In a reaction brake assembly, annularly shaped friction and opposing plates having radially extending friction surfaces on opposite sides of each plate; and a series of spaced, generally radially extending grooves in the friction surfaces of said friction plates, said grooves intersecting one anothertoform a pattern of diamond shaped landsthroughoutthe friction surfaces.

19. Friction and opposing plates as defined in Claim 18 in which said grooves extend from near the internal edge to near the external edge of each of the respective plates for receiving cooling and lubricating fluid.

20. A speed changing device substantially as hereinbefore described and as shown in the accompanying drawings.