GB2384532A

GB2384532A - Arrangement of drive shafts in a change gear transmission

Info

Publication number: GB2384532A
Application number: GB0201655A
Authority: GB
Inventors: Steve Harrison; Giovanni Hawkins
Original assignee: Eaton Corp
Current assignee: Eaton Corp
Priority date: 2002-01-25
Filing date: 2002-01-25
Publication date: 2003-07-30
Also published as: WO2003062674A1; GB0201655D0

Abstract

A change gear transmission 1, has a casing 2, an input shaft 39 and input gear 4 and output shaft 14. The input shaft 39 and a sleeve 5 of the input gear 4 constitute two parts of an input shaft assembly, connected by splines and a circlip 42, where the sleeve 5 is located inside the casing 2 of the transmission 1, and the input shaft 39 is located outside the transmission housing. Oil bores 31,32 may be provided in the input gear 4 for lubrication. Various other well known transmission parts may also be provided, eg, a countershaft 8, countershaft gears 11,12, a clutch 21, or bearings 6,9.

Description

Chance Gear Transmission This invention relates generally to a change gear transmission especially for a motor vehicle.

Generally, these transmissions comprise a housing, an input gear journaled within said housing, a mainshaft generally coaxial with said input gear and rotationally supported, at one of its ends, by bearing means in said input gear, at least one countershaft rotationally supported in said housing and driven by said input gear, a plurality of countershaft gears fixed to said countershaft, at least one of said countershaft gears being in continuous meshing engagement with said input gear, a plurality of mainshaft gears surrounding said mainshaft, and positive clutch means rotationally fixed to said mainshaft for selectively connecting said mainshaft to said input gear.

Transmissions of this type are well-known in the prior art. The basic concept of one of these prior art transmission is for example disclosed in EP 0 383 493 or US patent 4,944, 197. Typically, the transmission is housed within a single multi-piece housing. Transmissions are normally built as self-contained units. In some cases a bell housing is bolted or secured to a front end wall of the transmission. The bell housing contains the clutch assembly which is normally supplied as a separate unit. The rotating parts of the clutch assembly generally are co-axial with the transmission input shaft and the clutch driven plate is connected to the transmission input shaft to provide input to the transmission. The input shaft is supported by a bearing in the front wall of the transmission housing and carries an input gear for driving at least one countershaft assembly. The input gear is splined to a radially protruding collar or flange of the input shaft that is located in the transmission housing. On its end that extends into the transmission housing the input shaft is provided with a blind bore to receive a pilot end of the main shaft which is rotationally supported by the input shaft. The transmission input shaft normally extends outside the transmission, it may even extend some way beyond the clutch bell housing if one is fitted. Since the input shaft, on the outside of

the transmission housings reaches beyond the bell-shaped clutch housing that is bolted to the front wall of the transmission housing the whole transmission as a considerable packing volume. In cases when the transmission is made and shipped without a bell housing the shaft protruding will render it liable to damage in shipping and require substantial amount of extra packaging volume. Furthermore, in practice, transmissions of this sort are manufactured with different input shafts to suit customer needs and specific applications. This necessitates a multiplicity of types of the transmission that are built and that differ from one another only in the length and size of the input shaft. To exchange the input shaft in a complete transmission would not be practical because it would mean that the whole transmission would have to be disassembled. Finally, before leaving the factory the transmissions are usually put on the test stand and tested. In order to do this, lubricating oil must be put into the transmission housing and a prime mover adapted to couple with a variety of different input shafts must be used. Subsequent to the testing procedure it is usual practice to take the oil out of the transmission casing in order to avoid any oil leakage during shipment. Some customers prefer, however, to receive the transmission filled with the required quantity of lubricant oil.

It is an object of the invention to minimize the above mentioned disadvantages of the prior art and to provide a transmission which has a considerably reduced packing volume and which can easily be adapted to the different requirements of the customer and to reduce shipping weight.

To achieve this object the transmission according to the invention comprises the characteristics of claim no. 1.

A transmission according to the present invention is provided with a two-piece input shaft assembly. This has the advantage that the whole transmission can be built and sealed at the factory and shipped complete. The second component part of said two-piece input shaft assembly that actually couples with the clutch assembly and that is located on the outside of the transmission housing can be added later, for example, at the point where the transmission is dressed or just prior to its assembly into a powertrain. This enables the input shaft to be varied to suit the customer needs and specific applications without bringing about a multiplication of the number of versions of transmissions that are built.

Since the transmission can be shipped without an input shaft protruding from the transmission housing, the packing volume can be significantly reduced. With the exter-

nal portion of the input shaft removed the transmission housing is completely sealed and therefore no oil can escape from the housing if the transmission is shipped complete with its oil filling.

A further advantage is that no dirt or unwanted particles can enter the transmission because the input shaft is sealed.

This and other objects and advantage of the present invention may be appreciated by reference to the attached drawings taken in connection with the description of the preferred embodiment.

Brief Description of the Drawings Fig. 1 is a partial view, in section, of a change gear transmission according to the in- vention and Fig. 2 is a partial sectional view of the sleeve of the input gear of the transmission of fig. 1 with the input shaft inserted.

Referring now to the drawing, figure 1 illustrates a portion of a change gear transmission of the type comprising jaw clutches to selectively engage a selected ratio gear and wherein an input gear is non-rotatably connected to an input shaft, as by splines. Transmissions of this type are well-known in the prior art as may be seen by reference to US. Pat. Nos. 3,105, 395; 3,648, 546; 4,944, 197; EP 0 383 493; 0 491 514 and 0 096 911. The term"transmission"is used to designate a change speed transmission wherein the operator may select one of a plurality of single gear reductions.

The transmission 1 comprises a casing 2, of which a front wall 3, is shown in figure 1. In the casing 2 a preferably helically toothed input gear 4 is provided that is formed integrally with a coaxial cylindrical sleeve 5. The sleeve 5 is rotatably supported in a roller bearing 6 which is received in a bore 7 in the front wall 3 of the casing 2. The input gear 4 drives either a single countershaft 8 or simultaneously a plurality of countershafts 8 at equal speeds. The transmission of figure 1 is of the type having one single countershaft 8. The countershaft 8 is joumaled at one of its ends in a roller bearing 9 that is received in a cylindrical bore 10 in the front wall 3. The countershaft 8 is provided with countershaft gears of which countershaft gears 11 and 12 are illustrated in figure 1. The countershaft gears 11,12 are non-rotationally fixed to the countershaft

8 by means of splines 13. The helically toothed countershaft gear 11 of the countershafts 8 is in continuous meshing engagement with the input gear 4.

The transmission 1 is furthermore provided within the casing 2 with a main shaft 14 that is coaxially aligned with the input gear 4 and is provided with a cylindrical coaxial pilot portion 15 on its forward end rotatably received within a coaxial frustroconical bore 16 of the input gear 4. The pilot portion 15 is rotatably supported by a conical-roller bearing 17 having frustro-conical rollers 18 that are in engagement with the inner wall 19 of the frustro conical bore 16 of the input gear 4. On its rearward end the main shaft 14 is rotatably supported in the casing 2 by a bearing which is not shown.

A plurality of main shaft gears 20 surround the main shaft 14 and are selectively clutchable, one at a time, to the main shaft 14 for rotation therewith as is well-known in the art. Of these positive acting sliding clutches only one clutch 21 is illustrated in figure 1. This particular clutch 21 is utilized to either clutch the foremost main shaft gear 20 to the main shaft 14 or, alternatively to clutch the input gear 4 to the main shaft 14 to provide a direct drive relationship between the input gear 4 and the main shaft 14.

The clutches 21 are of a type well-known in the art. The basic concept of these clutches is disclosed for example in EP 0 096 911. Briefly, a clutch 21 includes a disc-shaped hub 22 which is non-rotatably connected by serrations 23 to the main shaft 14. An axially slideable internally toothed sleeve or collar 24 shown in figure 1 in a neutral position is engageable selectively with a toothed clutch element 25 non-rotatably connected to the adjacent end of the main shaft gear 20 and with a toothed clutch element 26 non-rotatably connected and supported by the adjacent cylindrical end of the input gear 4 by means of splines. Typically, the clutch sleeve or collar 24 is axially positioned by means for a shift fork or yoke associated with a shift bar housing assembly which is well-known in the art and not shown in the drawing. The clutch 21 is by the way of the well-known synchronized double acting claw clutch type.

The frustro-conical bore 16 in the input gear 4, at its foremost end, merges into a coaxial cylindrical bore 27 which is closed on its bottom side by an integral wall 29 of the input gear 4 and therefore forms a pocket-like chamber 30 that is located in an axial distance from the forward end of the pilot portion 15 of the main shaft 14 and of the roller bearing 17. At least one oil bore 31 that is parallel to the axis of rotation of the input gear 3 opens at one of its ends in a radial distance from the circumferential wall 28 of the bore 27 into the chamber 30 and is connected, at its other end, to a radially extending oil bore 32 opening between adjacent helical teeth 33 of the input gear 4.

The oil bores 31, 32 of which the radially extending oil bore 32 preferably has a smaller diameter than the axially extending oil bore 31, serve the purpose of lubricating the roller-bearing 17. In operation, with the input gear 4 and the counter shaft gears 11 rotating the gears are lubricated by oil that is supplied to the teeth of the gears in a wellknown way, for example by making the countershaft gear 11 dip into a supply of oil within the transmission housing 2. Due to the helical shape of the intermeshing teeth of the input gear 4 and the countershaft gear 11 oil is squeezed or pumped into the at least one radially extending oil bore 32 of the input gear 4, said radially extending bore 32 having a diameter that is small enough to prevent the oil from only vibrating within the oil bore 32. In this way oil is pumped against the action of centrifugal forces radially inwardly into the axial oil bore 31 from where it is delivered into the chamber 30. Since the at least one axial oil bore 31 opens into the chamber 30 in a radial distance from its circumferential wall 28 the oil streaming from the oil bore 31 into the chamber 30 will be thrown radially outwardly by centrifugal forces, the circumferential area between the opening of the bore 31 and the circumferential wall 28 of the chamber 30 thus forming an oil reservoir from which oil will be supplied to the bearing 17 along the outwardly flaring wall of the frustro conical bore 16.

On its forward side the sleeve 5 of the input gear 3 is provided with a coaxial cylindrical bore 35 that opens to the outside of the transmission housing 2, the sleeve 5 with its forward end being axially slightly recessed with respect to the outer surface of the front wall 3 of the transmission housing 2. The cylindrical bore 35 is closed at its bottom end by the wall 29 of the input gear 4. In this way the wall 29 of the input gear 3 completely separates the cylindrical bore 35 on the forward side of the input gear 4 from the frustro-conical bore 16 and the cylindrical bore 27 on the rearward side of the input gear 4. In fact, the cylindrical bore 35 is completely sealed from to the interior of the transmission housing 2. In the present case the intermediate wall 29 is an integral part of the input gear 4. However, in an alternative embodiment the wall 29 could also be a separate part that is sealingly fitted in the bore of the input gear 4.

On its inner wall the cylindrical bore 35 is provided with axially extending splines 36 which are best illustrated in figure 2. The splines 36 are separated from the plane bottom wall of the bore 35 by an unsplined cylindrical portion 37. Received with a tight fit within the cylindrical bore 35 is a splined end portion 38 of an input shaft 39 of the transmission 1 that couples at its distal splined opposite end portion 40 in a wellknown way with a clutch assembly that is not illustrated in the drawing. The end por-

tion 38 of the input shaft 39 is provided with axially extending splines 41 that are in interlocking engagement with the splines 36 of the sleeve 5 of the input gear 4. By means of the splines 41 on the external part of the input shaft 39 engaging with the cooperating splines 36 on the sleeve 5 inside the transmission housing 2, the input shaft 39 is positively connected to the input gear 4 and interlocked therewith. The input gear 4 is a first piece and the input shaft 39 is a second piece of a two-piece input shaft assembly. The distal end portion 40 of the input shaft 39 is provided with a cylindrical extension 400 of reduced diameter for being received in bearing means.

The sleeve 5 of the input gear 4 and the splined end portion 38 of the input shaft 39 are axially secured together either by friction or engaging by some form of a captive circlip 42 as it is illustrated in figures 1 and 2. The circular circlip 42 is received in a circumferentially extending groove 43 of the splined portion 38 of the input shaft 39.

The internal splines 36 of the bore 35 are provided with a similar circumferential groove 44 that is located in an appropriate distance form the bottom of the bore 35 thus allowing the resilient circlip 42 to snap into the groove 44 and thereby positively interlock the sleeve 5 and the input shaft 39 when the latter is axially pushed into the bore 35. The flanks of the groove 43 or of the groove 44 are chamfered to permit removal of the input shaft 39 by overcoming the snap action provided by the circlip 42.

Instead of the co-operating splines 36 and 41 on the sleeve 5 and on the main shaft 39 other means can be envisaged for engaging these two components. For example, the two components could be connected to one another by threads, co-operating serrations on the two components, etc. as the case may be. Briefly, the two components can have any convenient means for engaging and interlocking.

In an alternative embodiment of the invention the input gear 4 is not directly supported by a journal or bearing in the front wall of the housing. Instead, the input shaft 39 has a sleeve portion which slides over a mating, pinion or hub of the input gear 4. The sleeve portion of the input shaft 39 may engage the roller bearing 6 and be journaled. Any suitable form-locking means for engaging and interlocking the input gear 4 and the input shaft 39 may be provided on the input shaft 39 and the input gear 4.

The input shaft 39 and the sleeve 5 of the input gear 4 constitute two component parts of an input shaft assembly of which one component-the sleeve 5-is located inside the transmission housing 2 and the other component-the input shaft 39-is located

outside the transmission housing 2. The input shaft 39 can be varied to suit the customer needs and specific application without changing any parts of the transmission and especially without varying or replacing the input gear 4 or any part thereof. The axial length of the input shaft 39 can be chosen according to the requirements of the specific application. Typically, the input shaft 39 reaches beyond the forward edge 45 of a bellshaped clutch housing 46 that is schematically indicated in figure 1. The input shaft 39 and the input gear 4 or its sleeve 5 may be made of steels of different qualities and with different characteristics. These two components can be manufactured by using different technologies, e. g. one component can be dye formed while the other is made from stock by cutting, milling and turning operations, etc.

Since the input gear 4 is rotationally supported directly in the front wall 3 and its bore 35 is hermetically closed at its bottom end there is no fluid connection between the interior of the transmission housing 2 and its environment. The intermediate wall 29 in the input gear 4 protects the roller bearing 17 from the intrusion of any dirt or contamination coming from outside the transmission housing 2. The transmission 1 can be shipped without the input shaft 39 and with its casing containing a supply of lubricant oil since no oil can escape through the input gear 4. If necessary, a gasket 47 sealing the space between the sleeve 5 and the wall of the bore 10 in the front wall 3 to the atmosphere can be prvided.

Claims

Claims:

1. A change gear transmission (1) including: a housing (2), an input shaft assembly (4, 39), an output shaft, the input shaft assembly (4,39) being of at least two piece construction, a first piece (4) being substantially contained within the housing (2) and supported for receiving input drive and transmitting said input drive to the output shaft through one of a plurality of selectable gear sets, a second piece of said input shaft assembly, substantially outside the housing (2) passing through an opening (7) in a front wall (3) of the housing (2) and having a first end connectable to said first piece (4) of the input shaft assembly (4,39) to drivingly transmit input drive from a second end (40) of the input shaft assembly (4,39) adapted to re- ceive input drive from a prime mover or a clutch device.

2. The transmission of claim 1, wherein said first piece (4) comprises a bearing portion (5) that is rotationally supported by bearing means (9) in said transmis- sion housing (2).

3. The transmission of claim 2, wherein said bearing portion (5) is an integral part of the first piece (4).

4. The transmission of claim 2 or 3, wherein said bearing portion is an integral part of the second piece (39) of the input shaft assembly (4,39).

5. The transmission of claim 3, wherein said bearing portion includes a sleeve that comprises a bore (35) which is open to the outside of the transmission housing (2) and which is closed to the interior space of the transmission housing (2), said bore (35) being adapted to receive the second piece (39) of the input shaft as- sembly (4, 39).

6. The transmission of claim 1, wherein the two pieces of the input shaft assembly are positively connected to one another by form-locking means (36, 41).

7. The transmission of claim 6, wherein the form-locking means comprise splines (36, 41) provided on the two pieces and co-operating with one another.

8. The transmission of claim 5, wherein the first piece of the input shaft assembly (4,39) comprises an intermediate wall (29) between said bore (35) for receiving the second piece (39) of the input shaft assembly (4, 39) and between bore means (16) for receiving the bearing means (17) of a main shaft (14) and open- ing into the interior space of the transmission housing (2).

9. The transmission of claim 1, wherein the second piece (39) of the input shaft assembly (4,39) does not have any elements protruding beyond the outer sur- face of the transmission housing (2).

10. The transmission of claim 1, wherein the first piece (4) of the input shaft assem- bly (4,39) is provided with circumferential teeth (33) and oil bore means (31, 32) extending between the teeth (33) and a space within the first piece (4) and close to bearing means (17) for the main shaft (14).

11. The transmission of claim 10, wherein said oil channel means comprise a por- tion (32) extending in an essentially radially oriented direction and a portion (31) opening in said space (30) within the first piece (4) in a radial distance from a circumferential wall (28) of said space.

12. The transmission of claim 1, wherein the two pieces of the input shaft assembly (4,39) are made of different materials or of materials having different proper- ties.