COMPOSITE MECHANICAL - HYDRAULIC DRIVE SYSTEM WITH CONTINUOUS VARIATION OF TORQUE AND SPEED FROM ZERO TO MAXIMUM

The present invention relates to a mechanism enabling to transmit motion (from a source to output) by increasing or decreasing speed or torque in a continuous and smooth manner.

So far, variation of speed and torque in the current drive systems has been achieved in a staggered way, by changing and selecting gears of different diameters. Unfortunately, these mechanisms are complex since, in order to change gears in order to transmit motion to a point, there must be a system isolating motion supply at that point.

Even in drive systems that are considered to transmit motion continuously (automatic transmission), change of torque and speed is actually achieved, too, by changing gear systems through some instantaneous isolation in transmission. Even the belt speed and torque (CVT) variation system, although continuous, has a limited range of variation, reduced torque transmission, it wears out quickly and needs an isolation system anyway because transmission cannot start from zero.

In short, the current drive systems have a large volume and weight, are complex and have many moving parts resulting in frequent and easy wear and damage.

Thus, the object of the present invention is to provide a mechanism that truly enables us to transmit motion from zero to maximum smoothly and continuously, completely avoiding the presence of stepped gears and any transmission isolation system.

The solution to this problem lies with the composite mechanical-hydraulic system of continuously variable transmission and depends on how much torque the oil pressure pump (14) will allow to pass to the output system through the controlled flow valve (19). More specifically, the ever-changing motion of the mechanism is achieved according to the invention by means of the following technical characteristics.

The composite mechanical-hydraulic mechanism of continuous variation of torque and speed from zero to maximum (1) initially consists of a shaft (2) having a c-v joint at each end. One (3) of the c-v joints is connected via a shaft (2a) to a coupler (4) supported by a bearing (5), from which the rotary motion of a source is derived. The other c-v joint (6) is connected via a shaft (2b) to a planetary gear (7). The c-v-joints are intended to transmit the rotational motion of the power source to the planetary gear (7) so that the latter may perform two movements: a) an eccentric one, inside an internally toothed crown gear (8) and b) around itself ¹ . The planetary gear (7) is also supported on a rotating cylindrical base (10) by means of a bearing (9), its rotation centre being the point a at a distance L from the centre x of the base (10), the latter keeping the planetary gear (7) in a stable orbit and correct interlocking with the crown gear (8). In short, the rotating base (10) allows the planetary gear (7) to rotate around itself with centre a (via the bearing) but also, by performing an eccentric movement, (since its rotation centre a is located at a distance L from the centre x) to rotate as well inside the toothed crown gear (8), thus ensuring its constant interlocking with this gear. The rotating base (10) is supported externally by means of bearings (11) on the shell (20) of the mechanism in order to be able to rotate around itself. Also, in order to prevent vibrations due to the eccentric movement of the planetary gear (7) on the rotating base, two counterweights (15a) and (15b) are arranged on either side of the rotating base, at fixed positions relative to the centre x of point a, the centre of rotation of the planetary gear (7).

On the other side of the rotating cylindrical base (10) (in relation to that of the gear (7)), a gear rim with external serration (12) is fitted, which transmits the rotational movement of the base (10) to the gear (13) of an oil pressure pump (14). Thus, the oil pressure pump (14) rotates as long as the rotating base (10) rotates. Finally, a controlled flow valve (19) is fitted to the oil pressure pump outlet (14).

Thus, when the planetary gear (7) performs a) a cam movement, inside the crown gear - (8), it forces the cylindrical base (10) on which it rests to rotate around itself. This base, in turn, transmits through the externally toothed gear rim (12) the rotary motion to the gear (13) of the oil pressure pump, which simply recirculates the oil of the mechanism inside the system. That is, the result of the a) cam movement of the planet gear (7) is to transfer the rotational motion of the source to the oil pressure pump (14) through the cylindrical rotating base (10). On the contrary, in order to transfer the rotational motion of the power source to the output, the planetary gear (7) must perform only its b) movement, i.e. it should only rotate around itself, transferring its motion to the crown gear (8) with which it is in constant engagement. The crown gear (8) on the other side is connected to a shaft (16), supported by bearings (18), which in turn transmits the motion to the output. Thus, we can now realize that the rotational motion of the source can be transmitted in two directions: a. Through the externally toothed gear rim (12) to the oil pressure pump (14) (which simply recirculates the oil of the mechanism), insofar the gear (7) performs only its eccentric movement and b) through the crown gear (8) to the output shaft (16), insofar the planetary gear (7) rotates only around itself.

Choosing whether to transmit the source rotary motion to the oil pressure pump (14) or to the output depends on the controlled flow valve (19) installed in the oil pressure pump outlet (14).

When this valve (19) is closed the oil pressure pump (14) cannot rotate and neither can the rotating base (10) with which it is in constant interlocking. The reason is that when the pump gear (13) stops to rotate, the gear rim (12) that is mounted on the cylindrical base (10) automatically stops rotating as well. Upon ceasing the rotation of the base (10), the planetary gear (7) inside the gear (8) also ceases to rotate eccentrically. Therefore, the planetary gear (7) which transmits the motion from the source, being unable to perform its eccentric motion can only rotate around itself thus transmitting the motion through the crown gear (8) and the shaft (16) fitted to it, exclusively to the output system.

When the controlled flow valve (19) is open, it allows the oil pressure pump (14) to rotate freely simply circulating the oil in the closed circuit of the mechanism. The continuously rotating planetary gear (7) is now free to perform its eccentric motion inside the crown gear (8) and to transmit the motion only to the oil pressure pump (14) (since the base (10) following the movement of the planet gear (7), forces the externally toothed gear rim (12) which is adapted thereon to rotate with it). The toothed rim (12) in turn transmits the motion to the gear (13) of the oil pressure pump (14)). In this case the motion coming from the source, through the planet gear (7) is transferred to the oil pressure pump (14).

So far, we have described the operation of the mechanism when the controlled flow valve (19) is fully open and its operation when the valve (19) is completely closed. Now we can finally describe the operation of the mechanism when we successively restrict the rotation of the pump (14) via the valve (19).

Through the controlled flow valve (19) we begin to partially limit the oil circulation thus increasing the rotation resistance of the pump (14). This has the effect of limiting the eccentric motion of the planetary gear (7) so that part of its rotational motion begins to be transmitted to the crown gear (8) and therefore, including torque, to the output system. The more we restrict the oil circulation, the more the rotation resistance of the pump (14) increases and the eccentric movement of the planetary gear (7) reduces, thus increasing motion transmission to the crown gear (8). In this way, we reach smoothly and continuously the complete closure of the controlled flow valve (19) thus completely stopping the eccentric movement of the planetary gear (7) and thus transmitting all its rotational movement to the crown gear - i.e. the entire motion coming from the source to the output system. The controlled flow valve (19) therefore allows us to select the motion percentage to be transferred to the output system according to the requirements. An embodiment of the mechanism could be its use in a car engine in the position of the gearbox, thus completely avoiding the presence of stepped gears and any system of isolation of the transmission.