Vehicle gearbox with continuously variable gear ratio

Gear box, especially for motor vehicles, with a driving and a driven shaft, which carry pulleys, between which pulleys torque is transmitted by means of a V-belt or chain. The pulleys consist of discs movable towards and away from each other, to make variation possible of the speed ratio between the shafts. The movement of the discs and the clamping force against the V-belt is controlled with the aid of hydraulic cylinder devices. The hydraulic cylinder of the driving shaft is joined to a gear which is arranged concentrically with the cylinder and which engages a gear on the input shaft of the gear box.

The present invention relates to a gearbox especially for motor vehicles 
which carries belt pulleys on a driving and a driven shaft respectively, 
between which pulleys torque is transmitted by means of an endless 
flexible member, e.g. a V-belt or metal chain, and which consists of a 
pair of pulley members with variable spacing between them on the 
respective shaft to vary the effective radii of the belt pulleys and thus 
the transmission ratio between the driving and the driven shaft, said 
driving shaft having a fluid cylinder arranged concentrically with and 
joined to said shaft, and containing a slidable plunger joined to one 
pulley member. 
Hydraulically controlled gear boxes of this type, so called continuously 
variable transmissions, have of late been developed for use in motor 
vehicles. Compared with the usual type of continuously variable 
transmissions for motor vehicles, the speed ratio of which is controlled 
by vacuum members and centrifugal regulators, hydraulic control achieves 
both on the one hand more exact control of the speed ratio and the 
clamping force of the pulley members, and on the other hand the 
possibility of making the gear box more compact, thus saving space. 
The purpose of the present invention is to achieve an optimally compact 
gear box of the type described in the introduction, which is particularly 
suited for connection to a transverse engine. 
This is achieved according to the invention by the cylinder being joined to 
a gear arranged concentrically with the cylinder and engaging a gear on 
the input shaft of the gear box. 
In the gear box according to the invention, the torque from the input shaft 
is transmitted to the shaft of the pulley via the hydraulic cylinder, 
which means that the length of the shaft can be dimensioned without taking 
into account the gear. The result is an optimally short gear box, which is 
especially useful in transverse engines, where the lateral engine space is 
quite limited. A saving in weight is also achieved. 
In an improved embodiment of the gear box according to the invention, the 
reverse gear is also arranged concentrically with the cylinder, with both 
gears being made in one piece with the cylinder. Machining the teeth of 
the gears directly in the cylinder material provides both an economical 
manufacturing process and simple assembly by virtue of the fact that three 
parts can be molded as one unit.

In the FIGURE, 1 designates an input shaft, on which a gear 2 is rotatably 
journalled. 3 designates a clutch device. The gear 2 can be locked on the 
shaft 1 by means of a claw coupling 4, which is coordinated with a reverse 
gear 5. The gear 2 engages a gear 6 on a shaft 7 which carries a pulley 8. 
The FIGURE shows the gears in the neutral position. When the coupling 4 
with the gear 5 is moved to the right in the FIGURE, the gear 2 is locked 
on the input shaft 1 and forward drive is thus engaged. The reverse gear 
is engaged by an intermediate gear 9 (indicated with dash-lines) being 
brought into engagement with the reversing gear 5 and a gear 10 joined to 
the shaft 7. 
The gears 6, 10 are made in one piece with a cylindrical member 11, which 
acts as a hydraulic cylinder for a plunger 12, which is securely fixed to 
the one 13 of the two discs 13 and 14 of the pulley 8, which is 
displaceable on the shaft 7. The cylinder chamber 15 behind the plunger 12 
communicates with a pressure source via a connection 16. By having the 
outside of the hydraulic cylinder 11 form the gears 6 and 10, especially 
compact design is achieved. 
An output shaft 17 is provided in a corresponding manner with a pulley 18, 
which consists of two discs 19 and 20, of which the disc 19 is joined to a 
piston 21, which is slidable in a cylinder 22, the cylinder chamber 23 of 
which communicates with a pressure source via a connection 24. The disc 19 
is biased towards the disc 20 by a spring 25.