Range gearbox

A range gearbox of the planetary-type for a motor vehicle adapted to assist shifting between at least two operating positions, said range gearbox comprising:

• a planetary gear arrangement in which a sun gear and planet carrier are anchored against axial movement and a ring gear is axially shiftable between at least two positions for achieving at least two corresponding gear ratios of the range gearbox;
• the sun gear, the planet carrier and the ring gear interacting with each other via inter-engaging helical gear teeth;
• and
• wherein the inter-engaging helical gear teeth of the planetary gear arrangement are angled in such a manner in relation to a longitudinal axis of an shaft and an input shaft and an output shaft that an axial force arises on the ring gear from gear speed changes during synchronizing, and this axial force assists movement of the ring gear in the same direction as an external shifting force during to a low range configuration of the range gearbox.

A range gearbox of the planetary-type for a motor vehicle adapted to assist shifting between at least two operating positions, said range gearbox comprising:

• a planetary gear arrangement comprising three components including a sun gear, a planet carrier carrying a plurality of planet gears, and a ring gear;
• of said three components, at least one is axially shiftable between different axial positions for achieving corresponding different gear ratios of the range gearbox;
• said planetary gear arrangement enclosed in a housing and said sun wheel arranged on an input shaft and engaged with said planet gears, said planet gears being carried by said planet carrier connected to an output shaft and engageable with said axially displaceable ring gear;
• said ring gear being selectively lockable, via a coupling means, in a first coupling position in which said ring gear is non-rotatably connected to said housing in order to establish gearing between the input shaft and the output shaft, and in a second coupling position in which the ring gear is non-rotatably connected to one of the input shaft and the output shaft in order to establish direct drive therebetween;
• interacting tooth faces of the planetary gear arrangement being angled in such a manner in relation to the longitudinal axis of the input shaft and the output shaft that an axial force arises on the ring gear from gear speed changes during synchronizing, and this force, at least on shifting to a low range position, tends to move the ring gear in the same direction as an external shifting force;
• and
• the sun gear, the planet carrier and the ring gear interacting with each other via an interactive means for generating a shift-assisting force during gear change.

A method for providing gear shift-assistance in a range gearbox of the planetary-type for a motor vehicle between at least two operating configurations of the range gearbox, said method comprising:

• providing a planetary gear arrangement comprising three components including a sun gear, a planet carrier carrying a plurality of planet gears, and a ring gear;
• at least one of said three components being axially shiftable between different axial positions for achieving different gear ratios of the range gearbox;
• and at least two of said three components interacting via helically configured gear teeth, wherein helically configured gear teeth are angled in such a manner in relation to a longitudinal axis of an input shaft and an output shaft that an axial force arises on the ring gear from gear speed changes during synchronizing;
• and
• assisting movement of the ring gear in the same direction as an external shifting force during shifting to a low range configuration utilizing the axial force.