CA2126766A1 - Transmission output shaft drive assembly - Google Patents

Abstract

TRANSMISSION OUTPUT SHAFT DRIVE ASSEMBLY

Abstract An improved multiple speed gear transmission output shaft drive arrangement includes a synchronizer mounted for rotation with the output shaft, an internally toothed range gear coaxial with and rotatable relative to the output shaft and auxiliary countershaft assemblies including externally toothed auxiliary countershaft gears constantly meshed with the internally toothed range gear for driving engagement thereby.

Description

I EAT 0130 PUS 21 2 5 7 6 6 93-rTRN-021 TRANSMISSION OUTPllT SHAFI DRIVE ASSEl~/IBLY

Technical Field The present invention relates to compound transmissions having an auxiliary transmission section connected in series with a multispeed main transmission section and, more particularly, to an improved auxiliary transmission section including an internally toothed range gear driven by externally toothed auxiliary countershaft gears providing an output drive arrangement for transmitting high torque therethrough.

Background Art Compound change gear transmissions of the type having one or more auxiliary sections connected in series with a main transmission section are well known in the prior art. 8riefly, by utilizing main and auxiliary transmission sections connected in series, assuming proper sizing of the ratio steps, the total of available transmission ratios is equal to the product of the main and auxiliary section ratios. By way of example, at least in theory, a compound change gear transmission comprising a four (4) speed main section connected in series with a three (3) speed auxiliary section will provide twelve (4x3=12) available ratios.

Auxiliary transmission sections are of three general types: range type, splitter type or combined range/splitter type.

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2 1 2 G 7 6 b EAT 0130 PUS -2- 93-rTRN 021 In compound transmissions having a range type auxiliary section, the ratio step or steps may ~e greater, equal or less than the total ratio coverage of the main transmission section and the main section is shifted progressively throu~h its ratios in each range.
Examples of compound transmissions ~aving range type auxiliary sections may be seen by reference to U.S.
Patent Nos. 3,105,39r.; 2,637,222 and 2,637,221.
~0 ._ In compound transmissions having a splitter type auxiliary section, the ratio steps of the splitter auxiliary section are less than the ratio steps of the main transmission section and each main section ratio is split, or subdivided, by the splitter section. Examples of compound change gear transmissions having spl$tter type auxiliary sectionæ may be seen by reference to U.S.
Patent Nos. 4,290,515; 3,799,002; 4,440,037 and 4,527,447.

In a combined range and splitter type auxiliary section, or sections, both range and splitter type ratios are provided allowing the main section to be progressively shifted through its ratios in at least two ranges and also allowing the main section ratios to be ~ split in at least one range.
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One example of ~ compound transmission having a single combined range~splitter type auxiliary section may be seen by reference to U.S. Patent Nos. 3,2$3,61 3,648,546, and to publication Small Scale ~, J . , _:

, ,.~., ,. : : : ' l i~l ` 21267~6 EAT 0130 PUS -3- 93-rTRN-021 Print No. 016-AD; Fuller~ Transmissions;
Models T-14613, RT0-14613, RT00-14613, published March 1981 by Eaton Corporation, assignee of this invention. Another example is the "Ecosplit"~ model of transmission sold by Zahnradfabrik Friedri~hshafen Aktiengeseushaft of Friedrichshafen, Federal Republic of Germany which utilizes a separate splitter auxiliary section in front of, and a separate range auxiliary section behind, the main transmission section.~
It should be noted that the terms main and auxiliary sections are relative and that if the designations of the main and auxiliary sections are reversed, the type of auxiliary section (either range or splitter) will also be reversed. In other words, given what is conventionally considered a four-speed main section with two-speed range type auxiliary section, if the normally designated auxiliary is considered the main section, the normally designated main section would be considered a four-speed splitter type auxiliary section therefor. By generally accepted transmission industry convention, and as used in this description of the invention, the main transmission section of a compound transmission is that section which contains the largest (or at least no less) number of forward speed ratios, which allows selection of a neutral position, which contains the reverse ratio(s) and/or which is shifted (in manual or semiautomàtic transmissions) by manipulation of a shift bar or shift rail or shift shaft/shift finger assembly as opposed to master/slave valve/cylinder arrangements or the like.
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EAT 0130 PUS -4- 93-rTRN-021 ,-A conventional auxiliary transmission section such as that disclosed in U.S. Patent No. 4,754,665 includes an auxiliary section input shaft and an output shaft cooperably forming a mainshaft assembly, and an auxiliary countershaft assembly. The auxiliary transmission section includes three gear layers, combined range and splitter geaxing and four distinct selectable auxiliary section ratios. Auxiliary section countershaft gears drive externally toothed range gears to provide an output torque flow path.
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Disclosure Of Invention ..
An object of the present invention is to provide a new and improved compound change gear transmission that utilizes an internally toothed range gear in the output torque flow path to increase the torque capacity of the output torque flow path.

Another objective of the present invention is to provide a new and improved compound gear transmission having longer life gearing because of the internal mesh of the internally toothed range gear which reduces pitting and bending stresses.

Another object of the present invention is to provide a new and improved compound change gear transmission having balanced load sharing between main and auxiliary countershafts because of the internally toothed range gear and its ability to deflect and align deshing gear teeth.

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EAT 0130 PUS -5- 93-rTRN-021 In carrying out the above object, the compound transmission includes an auxiliary transmission section in series with a main transmission section wherein the auxiliary transmission sectlon includes an improved output shaft drive arrangement. The output shaft drive arrangement comprises a synchronizer mounted for rotation with an auxiliary transmission section output shaft, and an internally toothed range qear coaxial with and rotatable relative to the output shagt. The internally toothed range gear is in torque flow communication with the synchronizer and a pluralit~ of auxiliary countershaft assemblies. Each auxiliary countershaft assembly includes an auxiliary countershaft and a first auxiliary countershaft gear rotationally fixed to the auxiliary countershaft. Each auxiliary countershaft gear is constantly meshed with the internally toothed range gear for driving engagement thereby.

Preferably, two auxiliary countershaft drive gear assemblies are on diametrically opposed sides of the output shaft and each has an externally toothed auxiliary countershaft gear that drives the internally toothed range gear. Such an arrangement allows the transmission of high torque values through the output shaft drive arrangement.

The above object and other objects, features, and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.

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EAT 0130 PUS -6- 93-rTRN-021 Brief Description Of The Drawin~s FIGURE 1 is a schematic illustration of a prior art compound transmission section having a multispeed main transmission section connected in series with an auxiliary transmission section;

FIGURE 2 is a schematic illustration of the prior art compound transmission of FIGURE 1 including and illustrating an improved output shaft dr-ive arrangement constructed in accordance with the present invention; and FIGURE 3 is a schematic illustration of an improved compound transmission constructed in accordance with the present invention including the improved output shaft drive arrangement.

Best Mode For Carrying Out The Invention Certain terminology will be used in the following description for convenience only and will not be limiting. The words "upwardly", "downwardly", "rightwardly", and "leftwardly" will designate directions in the drawings to which reference is made.
~he words "forward" and "rearward" will refer respectively to the front and rear ends of the transmission as conventionally mounted in the vehicle, being respectively to the left and right sides of the prior art main transmission section illustrated in Figure 1.

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EAT 0130 PUS -7- 93-rTRN-021 The term "compound transmission" is used to designate a change speed or change gear transmission having a main transmission section and an auxiliary transmission section connected in series whereby the 5selected gear reduction in the main transmission section may be compounded by further selected gear reduction in the auxiliary transmission section. The term "upshift"
as used herein shall mean the speed gear ratio is changed from a lower value to a higher value. The term 10"downshift" as used herein shall means the shifting from a higher speed gear ratio to a lower speed gear ratio.
The terms "low speed gear" or "low gear" as used herein shall designate a gear ratio utilized ~or relatively lower forward sp~ed operation in a transmission, i.e. a 15set of gears having a higher ratio of reduction of output shaft speed relative to the speed of the input shaft. "Synchronized clutch assembly" and words of similar import shall designate a clutch assembly utilized to non-rotatably couple a selected gear to a 20shaft ~y means of a positive clutch in which attempted engagement of said clutch is prevented until the members of the clutch are at substantially synchronous rotation and relative large capacity friction means are associated with the clutch members and are sufficient, 25upon initiation of a clutch engagement, to cause the clutch members and all members rotating theréwith to rotate at a substantially synchronous speed.

Referring now to Figure 1, there is ¦ schematicall~ illustrated a well known and highly ¦ 30commercially successful eighteen forward speed compound transmission 10. Transmission 10 comprises a main transmission section 12 connected in series with an auxiliary transmission section 14. Typically, the 21267~ ~

EAT 0130 PUS -8- 93-r~RN-021 transmission 10 is housed in a single housing and includes an input shaft 16 driven by a prime mover such as diesel engine E through a selectively disengaged, normally engaged friction master clutch C having an input or driving section 18 drivingly connected to the engine crankshaft 20 and a driven portion 22 rotatably fixed to the transmission input shaft.

In the main transmission section 12, the input shaft 16 carries an input gear 24 for simultaneously driving a plurality of substantially identical main section countershaft assemblies 26 and 26a at substantially identical rotational speeds. In the transmission 10 illustrated, two substantially identical main section countershaft assemblies are provided on diametrically opposite sides of a mainshaft 28, which mainshaft is generally coaxially aligned with the input shaft 16. Each of the main section countershaft assemblies 26 and 26a comprises a main section countershaft 30 supported by bearings 32 and 34 in housing H, only a portion of which is schematically illustrated.

Each of the main section countershafts 30 is provided with an identical grouping of main section countershaft gears 38, 40, 42, 44, 46 and 48, fixed for rotation therewith. A plurality of main section drive or mainshaft gears 50, 52, 54, 56 and 58 surround the mainshaft 28 and are selectively clutchable, one at a time, to the mainshaft 28 for rotation therewith by sliding clutch collars 60, 62 and 64 as is well known in the art. Clutch collar 60 may also be utilized to clutch input gear 24 to mainshaft 28 to provide a direct drive relationship between input shaft 16 and mainshaft ~!i`:: ` -- :~ : : :;. : - ".~ ~,f.

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EAT 0130 PUS -9- 93-rTRN-021 28. Preferably, each of the main section mainshaft gears encircles the mainshaft 28 and is in continuous meshing engagement with and is floatingly supported by the associated countershaft gear group.

S Typically, clutch collars 60, 62 and 64 are axially positioned by means of shift forks (not illustrated) associated with a shift bar housing assembly (not illustrated) as well known in the prior art. Clutch collars 60, 62 and 64 are of the well known non-synchronized double acting jaw clutch type.

With continued reference to Figure 1, main section mainshaft gear 58 is the reverse gear and is in continuous meshing engagement with countershaft gears 48 by means of conventional intermediate idler gears (not shown). It should also be noted that while main transmission section 12 does provide five selectable forward speed ratios, the lowest forward speed ratio -~
namely, that ratio provided by drivingly connected mainshaft drive gear 56 to mainshaft 28 is often of such a high gear reduction as to be considered a low or -~
"creeper" gear which is utilized only for starting of a -~
vehicle under severe conditions and is usually not utilized in the high transmission range and/or may not be split in the low transmission range.

ZS Jaw clutches 60, 62 and 64 are three-position clutches in that they may be positioned in a centered, non-engaged position as illustrated or in a fully ~ -rightwardly engaged or fully leftwardly engaged posltion.

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~ 2~2~7~3 EAT 0130 PUS -10- 93-rTRN-021 Auxiliary transmission section 14 includes two substantially identical auxiliary countershaft assemblies 68 and 68A, each comprising an auxiliary countershaft 70 supported by bearings 72 and 74 in housing H and carrying three auxiliary section countershaft gears 76, 78 and 80 fixed for rotation therewith. Auxiliary countershaft gears 76 are constantly meshed with and support auxiliary section splitter gear 82 which surrounds mainshaft 28.
Auxiliary countershaft gears 78 are constantly meshed with and support auxiliary section splitter/range gear 84 which surrounds the output shaft 86 at the end thereof adjacent the coaxial end of mainshaft 28.
Auxiliary section countershaft gears 80 constantly mesh and support auxiliary section range gear 88, which surrounds the output shaft 86. Accordingly, auxiliary section countershaft gears 76 and splitter gear 82 define a first gear layer, auxiliary section countershaft gears 78 and splitter/range gear 84 define a second gear layer and auxiliary section countershaft gears 80 and range gear 88 define a third layer, or gear group of the combined splitter and range type auxiliary transmission section 14.

A sliding two position jaw clutch collar 90 is utilized to selectively couple either the splitter gear 82 or the splitter/range gear 84 to the mainshaft 28, while a two position synchronized assembly 92 is utilized to selectively couple the splitter/range gear 84 or the range gear 88 to the output shaft 86.

FIGURE 2 illustrates the hereinabove described prior art compound transmission of FIGURE 1 having an improved output drive arrangement. With continuing ~ 21267~~) EAT 0130 PUS -11- 93-rTRN-021 reference to FI¢URE 2, an internally toothed range gear 112 has been substituted for the externally toothed range gear 88 seen in FIGURE 1 with the result that range gear 112 provides superior torque transmission capacity over the externally toothed range gearing and improves gear life because of the internal mesh which reduces stresses.

Immediately following, and by way of example, is a detailed description of the output shaft drive arrangement applied to a novel compound transmission ~-illustrated in FIGURE 3.

With reference to FIGURE 3, the multiple ratio transmission lOA shown therein is a fourteen-forward speed, two-reverse speed, compound manually operated transmission wherein main transmission section 12A is connected in series to the auxiliary section 14A. The main transmission section 12A includes a two-speed input splitter section and auxiliary section 14A includes a three speed range section. Typically transmission lOA
is housed within a single housing (not shown) and includes an input shaft 122 driven by a prime mover (not shown) such as a well known diesel engine or the like.

In the main transmission section 12A input shaft 122 drives a two position clutch collar 126.
Clutch collar 126 is actuated by an actuator 128 such as a two-position piston, or the like, and has a first position for engaging torque input splitter gear 132 to the input shaft and a second position for engaging the second splitter gear 134 to the input shaft. The input splitter s~ction thus defines the first clutch S1 and second clutch S2 which are mutually exclusively 2 ~
EAT 0130 PUS -12- 93-rTRN-021 engageable to couple torque input splitter gear 132 or second splitter gear 134 to the input shaft 122.

~orque input splitter gear 132 and second splitter gear 134 simultaneously drive a pair of substantially identical main section countershaft assemblies 138 and 138A at substantially identical rotation speeds. In the transmission illustrated, two substantially identical main section countershaft assemblies are provided on diametrically sides of an intermediate shaft which is generally coaxially aligned with the input shaft 122 and output shaft 124. Each of the main section countershaft assemblies 138 and 138A, comprise a main section countershaft 142 supported by bearings and provided with an identical grouping of main lS section countershaft gears 144,146,148,150 and 152, fixed for rotation therewith. Main section drive gears 154,156 and 158 surround the intermediate shaft 140 and are selectively clutchable, one at a time, to the intermediate shaft 140 for rotation therewith by sliding clutch collars 160 and 162 as is well known in the prior art. Clutch collar 160 may also be utilized to clutch second splitter gear 134 directly to intermediate shaft 140 to provide a direct driving relationship therebetween. Of course, with clutch S2 engaged, second splitter gear 134 will rotate with input shaft 122.

Main section drive gears 154,156 are in continuous meshing engagement with and floatingly supported by the associated main section countershaft gears 148,150 and main section intermediate shaft gear lS8 is the reverse gear and is in continuous meshing engagement with countershaft gear 152 by means of conventional intermediate idler gears 164.

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EAT 0130 PUS -13- 93-rTRN-021 Main section clutch collars 160 and 162 are axially positioned by shift forks 166 and 168, respectively, and are typically manually controlled by means of a shift lever or the like. The rlutch collars 160 and 162 are of the well known nonsynchronizing type of the well known double acting jaw clutch type.
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It may be seen, that the manually controlled main section 12A defines six clutches Sl,S2,Jl,J2,J3 and JR, respectively, which are mutually exclusively engageable to drivingly couple either torque input second splitter gears 132,134, main section drive gears 154,156, or reverse intermediate section drive gear 158, respectively, to the input or intermediate shafts 122,140.

lS The combined range auxiliary section 14A
includes two substantially identical auxiliary countershaft assemblies 170 and 170A, each comprising an auxiliary countershaft 172 supported by bearings in a housing and carrying two auxiliary section countershaft gears 174 and 176 fixed for rotation therewith.
Auxiliary section countershaft gears 176 are constantly meshed with in support of intermediate shaft output gear 178. Auxiliary countershaft gears 174 are constantly meshed with and support auxiliary internally toothed range gear 180 which surrounds the output shaft 124.

A sliding two-position jaw clutch collar 184 is utilized to selectively couple the main countershaft 142 to the auxiliary countershaft 172, thus defining a clutch J4. Clutch collar 184 is actuated by an actuator 188 such as a two position piston, or the like, and has a first position for engaging main countershaft 142 to - 212676~
EAT 0130 PUS -14- 93-rTRN-021 auxiliary countershaft 172 and a second position wherein the countershafts are disengaged.

Synchronized clutch assembly 186 defines two mutually exclusively engageable range torque flow paths H and L, respectively. In low range, clutch assembly 186 is engageable to couple range gear 180 to the output shaft 124 and in high range, clutch assembly 186 is engageable to couple intermediate shaft output gear 178 to the output shaft 124. Actuator 190 is a two-position fluid actuated piston for actuating selection of the desired torque flow path H,L.

With continued reference to FIGURE 3, the auxiliary transmission section 14A includes the improved output shaft drive arrangement wherein the output shaft 124 includes internally toothed output shaft range gear 180 coaxial with and rotatable relative to the output shaft. The first auxiliary countershaft gears are externally toothed and constantly meshed with the internally toothed range gear 180. Load sharing between main and auxiliary countershafts 142,172 is improved because of the internally toothed range gear and its ability to deflect and align meshing gear teeth. The internal tooth construction of the range gear 180 provides a superior torque transmission capacity over the conventional externally toothed gearing.

While the best mode for carrying out the invention has been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments ,,,,,",,", ",,""~ " ~ ;" ~ ", ~ , ,",,~

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EAT 0130 PUS -15- 93-rTRN-021 for practicing the invention as defined by the following claims.
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Claims (9)

1. In a multiple speed gear transmission, an output shaft drive arrangement comprising:
a synchronizer mounted for rotation with said output shaft;
an internally toothed range gear coaxial with and rotatable relative to said output shaft; said internally toothed range gear being in torque flow communication with said synchronizer; and an auxiliary countershaft assembly, said assembly comprising an auxiliary countershaft and a first auxiliary countershaft gear rotationally fixed to said auxiliary countershaft, said auxiliary countershaft gear being constantly meshed with said internally toothed range gear for driving engagement thereby.

2. The gear transmission of claim including a plurality of countershaft assemblies circumferentially spaced around the output driveshaft.

3. The gear transmission of claim 2 further including an auxiliary countershaft drive gear assembly for rotating said plurality of auxiliary countershaft assemblies simultaneously.

4. The gear transmission of claim 3 wherein said plurality of auxiliary countershaft assemblies are defined by first and second auxiliary countershaft assemblies on diametrically opposite sides of said output shaft.

5. The gear transmission of claim 4 wherein said countershaft drive gear assembly includes a drive gear generally coaxial with and rotatable relative to said output shaft and second auxiliary countershaft gears rotationally fixed to said auxiliary countershafts and constantly meshed with said drive gear.

6. The gear transmission of claim 4 further including a main transmission section comprising:
an input shaft;
an intermediate shaft disposed between said input and output shafts;
first and second main countershafts;
a plurality of intermediate shaft drive gears mounted rotatably on said intermediate shaft;
a plurality of first and second main counter-shaft gears fixed for rotation with said first and second main countershafts;
said intermediate shaft drive gears being selectively clutchable and in continuous meshing engagement with said first and second main countershaft gears; and an intermediate shaft output gear for driving said second auxiliary countershaft gears.

7. The gear transmission of claim 5 wherein said countershaft drive gear assembly includes clutch means for engaging said main countershafts to said auxiliary countershafts for rotation therewith.

8. The gear transmission of claim 7 wherein said synchronizer is a two-way synchronizer.

9. The gear transmission of claim 4 further including a main transmission section comprising:
an intermediate shaft disposed between the input and output shafts;
a main countershaft;
a torque input splitter gear coaxial with and rotatable relative to said input shaft;
a second splitter gear coaxial with said input and intermediate shafts and mounted for rotational engagement with said input and intermediate shafts;
third, fourth and fifth intermediate shaft splitter drive gears mounted rotatably on said intermediate shaft;
first, second, third, fourth and fifth main countershaft gears fixed for rotation with said main countershaft; said first countershaft gear being in continuous meshing engagement with said torque input splitter gear; said second countershaft gear being in continuous meshing engagement with said second splitter gear; said third through fifth countershaft gears being in continuous meshing engagement with said third through fifth splitter drive gears;
said splitter gears being selectively clutchable;
an intermediate shaft output gear fixed for rotation with said intermediate shaft;
an output shaft range gear coaxial with and rotatable relative to the output shaft;
a two-way synchronizer coupling means fixed for rotation with the output shaft and operable for coupling said intermediate shaft output gear and for coupling said output shaft range gear to said output shaft;

an auxiliary countershaft gear assembly comprising an auxiliary countershaft, a first auxiliary countershaft gear fixed for rotation on said auxiliary countershaft and constantly meshed with said output shaft range gear, and a second auxiliary countershaft gear surrounding said auxiliary countershaft and constantly meshed with said intermediate shaft output gear; and a clutch assembly fixed for rotation on said auxiliary countershaft and having a position for coupling said auxiliary countershaft to said main countershaft.