Transmission suitable for a motor vehicle, shafts therefor and method of producing such shafts

Abstract

A transmission, particularly for a motor vehicle, having at least two torque transmitting shafts, shafts suitable for use in such a transmission, and a method for the production such shafts. At least one of the shafts is composed of a shaft base body ( 10 ) and at least one gearwheel ( 3 a , 4 a ), which is at least substantially finished separately from the shaft and subsequently is fixed to the shaft in such a way as to transmit torque available at the shaft or input torque by the gearwheel having a hollow hub body ( 13, 14 ) and being axially pressed onto a seat ( 11, 12 ) on the shaft base body so as to form a frictional connection which transmits the torque from the shaft to the gearwheel.

1 . A shaft having a gearwheel fixed thereon for direct torque transmission, wherein said shaft comprises a shaft main body and at least one gearwheel having a hollow hub body axially pressed onto a seat on the shaft main body to form a friction-locked connection for transmitting torque between the gearwheel and the shaft. 
   
   
       2 . A transmission comprising at least two torque-transmitting shafts each having at least one gearwheel fixed thereon for direct torque transmission, wherein at least one of said shafts is a shaft as recited in  claim 1 . 
   
   
       3 . A transmission as recited in  claim 1 , wherein said gearwheel is essentially finish machined prior to being pressed onto the seat on the shaft main body and said at least one shaft is a main transmission shaft, an output shaft, or a countershaft. 
   
   
       4 . A shaft as recited in  claim 1 , wherein the shaft main body is assembled from at least two axial sections joined to each other. 
   
   
       5 . A shaft as recited in  claim 1 , wherein the shaft main body has an at least partially tubular structure. 
   
   
       6 . A shaft as recited in  claim 5 , wherein at least one gearwheel is pressed onto a seat in a tubular region of the shaft main body. 
   
   
       7 . A shaft as recited in  claim 5 , wherein the shaft main body comprises two end regions at opposed axial ends thereof and at least one center region between the two end regions, wherein at least one center region has a tubular structure. 
   
   
       8 . A shaft as recited in  claim 7 , wherein at least one of said end regions is joined directly to the tubular center region. 
   
   
       9 . A shaft as recited in  claim 5 , wherein the shaft main body comprises two components, each having an end region and a tubular region, wherein the tubular regions are oriented toward one another, and the components are joined to one another by axially connecting the tubular regions. 
   
   
       10 . A shaft as recited in  claim 4 , wherein the axial sections are welded together. 
   
   
       11 . A shaft as recited in  claim 10 , wherein the axial sections are welded together by laser beam welding or friction welding. 
   
   
       12 . A shaft as recited in  claim 5 , wherein the tubular region is produced by a metal forming technique selected from the group consisting of cold forming and hot forming. 
   
   
       13 . A shaft a recited in  claim 7 , wherein at least one end region or a center region is produced at least partially tubular by massive forming. 
   
   
       14 . A shaft as recited in  claim 1 , wherein at least two gearwheels are rotationally fixed on said shaft main body, and at least one further undivided functional body is arranged on said shaft main body axially between said two gearwheels, said at least one further functional body being selected from the group consisting of bearings, idlers and synchronization units. 
   
   
       15 . A shaft as recited in  claim 1 , wherein the gearwheel has an axial length substantially equal to the axial length of the gearing of the gearwheel. 
   
   
       16 . A shaft as recited in  claim 1 , wherein at least one gearwheel is provided with axial openings. 
   
   
       17 . A shaft as recited in  claim 5 , wherein the shaft main body is a one piece, hollow shaft. 
   
   
       18 . A shaft as recited in  claim 5 , wherein the at least partially tubular shaft main body has at least one closed end. 
   
   
       19 . A shaft as recited in  claim 18 , wherein the at least one closed end is liquid tight. 
   
   
       20 . A method for producing a shaft main body, said method comprising:
 providing a preform produced from a solid material by mass forming, said preform having a first partial region having a shape at least approximately the same as a final shape of a partial region of the shaft main body to be produced, and said preform comprising a material reserve axially adjoining said first partial region, said material reserve having a shorter axial extension than and a diameter at least equal to a maximum diameter of a remaining portion of the shaft main body to be produced; and   subjecting said material reserve to swaging to form said material reserve into the remaining portion of the shaft main body.   
   
   
       21 . A method as recited in  claim 20 , wherein said material reserve is formed into the remaining portion of said shaft main body by rotary swaging. 
   
   
       22 . A method as recited in  claim 20 , wherein said shaft main body has at least one gearwheel having a hollow hub body fixed on a seat on the shaft main body, said method further comprising axially pressing the gearwheel onto the seat on the shaft main body to form a friction-locked connection for directly transmitting torque between the gearwheel and the shaft. 
   
   
       23 . A method as recited in  claim 22 , wherein at least one functional area selected from the group consisting of bearing seats, gear teeth, bearing races, and gearwheel seats is finish machined on the shaft main body prior to axially pressing the gearwheel onto the gearwheel seat on the shaft main body. 
   
   
       24 . A method as recited in  claim 20 , wherein said preform is at least partially hollow. 
   
   
       25 . A method as recited in  claim 20 , wherein said preform is continuously hollow along the entire length thereof. 
   
   
       26 . A method as recited in  claim 24 , wherein said preform has a closed section in an axial end area of the first partial region. 
   
   
       27 . A method as recited in  claim 26 , wherein said closed section is formed from a hollow body by rotary swaging. 
   
   
       28 . A method as recited in  claim 20 , wherein said remaining portion of the shaft main body is initially hollow, and an axial end area of said remaining portion is closed at least liquid-tight by rotary swaging. 
   
   
       29 . A method as recited in  claim 20 , wherein at least one functional area on said shaft main body is brought at least approximately to finished dimension by rotary swaging, said at least one functional area being selected from the group consisting of bearing seats for mounting the shaft, areas for forming synchronization gearing, bearing races for roller bodies for mounting idlers, and hub seat areas for mounting axially pressed-on gearwheels.