Continuously variable transmission for heavy duty vehicles

A continuously variable transmission for heavy duty vehicles, in which the classic hydraulic torque converter is permanently removed, comprising at least two planetary gear assemblies; a hydraulic pump, used as a gradual brake; a hydro-mechanical device for transforming the torque generated by the drive engine of the vehicle into a variable torque; a hydraulic regulator to control all torque variations in the hydro-mechanical device; a reverse drive mechanism that controls a forward or reverse movement of the vehicle; and a freewheel that allows for a transmission of a different variable gear ratios from the drive engine of the vehicle to at least one of the driving wheels or caterpillars.

REFERENCES CITED

U.S. Patent Documents

BACKGROUND OF THE INVENTION

This invention relates to a continuously variable transmission for heavy duty vehicles, suitable for heavy duty trucks, agriculture tractors, some military heavy vehicles as battle tanks as well as for other types of vehicles. The transmission comprises at least two planetary gear assemblies; a freewheel; an oil pump, used as a gradual brake; and a flow control valve, automatically driven by means of a hydraulic regulator, for adjusting the torque transmission from the drive engine of the vehicle to at least one of the driving wheels or caterpillars.

DESCRIPTION OF THE RELATED ART

A typical automatic transmission for automobiles usually comprises a hydraulic torque converter; some planetary gear assemblies; some brake devices; and a control system, for transmitting the torque generated by a combustion engine to the driving wheels of the vehicle, wherein the torque is always transmitted in several stages and never in the form of continuously variable-way.

A more recently developed transmission for automobiles generally includes a set of adjustable pitch pulleys working in cooperation with a belt for variably transmitting the torque from the drive engine of the vehicle to the driving wheels. Belt structure of the type designed for those transmissions has been improved several times in order to provide an acceptable durability, however only a limited torque can be transmitted using such technology, however it is not suitable to heavy duty vehicles.

According to the present invention, the torque generated by the vehicle engine is transmitted to the driving wheels combining some operative features and several parts of a typical automatic transmission with the performance and benefits of a continuously variable transmission. Moreover, the results in doing so include an improvement in fuel efficiency standards, a faster acceleration, easier repairs, and a lower production and maintenance cost.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a new continuously variable transmission for heavy duty vehicles in a compact and lighter unit with a simplified design, also suitable for military battle tanks as well as for other motorized vehicles in civil uses which include hybrid electric types.

It is also an object of the invention to improve strategic mobility in the military ground transportation in order to arrive timely, in a cost effective way, allowing a substantial improvement in fuel efficiency standards, increasing autonomy.

It is also an object of the invention to provide a structure that allows to carry out repairs made by repairmen not specialized in automatic transmissions.

It is an object of the invention to reduce weight and volume as a result of the permanent removal of the hydraulic torque converter.

It is also an object of the present invention to provide a new transmission at a lower production cost.

It is another object of the invention to provide a reliable, robust and durable transmission, requiring less repairs needs.

These and other objects, features and advantages of the present invention will become more clear when the drawings as well as detailed description be taken into consideration.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to a continuously variable transmission for heavy duty vehicles including hybrid electric trucks of any loading capacity, agricultural tractors, battle tanks and other motorized equipments to transmit a variable torque from the internal combustion engine or the electric motor of said vehicles to at least of one of the driving wheels or caterpillars.

More specifically, the embodiment of the present invention shown inFIG. 1andFIG. 2includes at least two planetary gear assemblies100and200; a freewheel4; an oil pump11acting as a gradual brake; and a flow control valve15controlled by a hydraulic regulator as shown inFIG. 3.

Accordingly with the references of the embodiment ofFIG. 1andFIG. 2, the torque generated by the drive engine of the vehicle is transmitted by means of an input shaft1to a satellites carrier2of a secondary planetary gear assembly100and at the same time to a sun gear3of a main planetary gear assembly200. A freewheel4is connected to a ring gear5of the main planetary gear200allowing said ring gear to rotate only in the same way as engine does but braked at opposite direction. On the other hand said sun gear3transmits the torque from the input shaft1to a plurality of satellites6which lean back against the ring gear5in such a way that the rotation movement of a carrier7of the main planetary gear200can be transmitted to an output shaft8with a torque which is the highest available, taken into account the dimensions of the sun gear3as well as the ring gear5of the planetary gear assembly itself.

It is said before that the torque generated by the drive engine of the vehicle was also transmitted by means of the input shaft1,FIG. 1andFIG. 2, to the satellites carrier2, of the secondary planet gear assembly100, in which a sun gear9is connected by means of a shaft10to an impeller of an hydraulic pump11. A ring gear12of the secondary planetary gear assembly100is also connected to a satellites carrier7of the main planetary gear assembly200by means of a shaft13allowing a permanent connection to the driving wheels by means of the output shaft8in such a way that when the wheels of the vehicle are stationary, said ring gear12remains stopped too and as a result, the rotation of the carrier2which includes the plurality of satellites14, is transmitted to the sun gear9and to the impeller of the hydraulic pump11by means of the shaft10.

Considering that a flow control valve15,FIG. 2andFIG. 3controls the oil flowing through the hydraulic pump11, at a fully open position of the valve15, the sun gear9and the impeller of the oil pump11rotates free by the action of the satellites carrier2and no movement is transmitted to the ring gear12.

At a fully closed position of the valve15, both, the sun gear9and the impeller of the pump11are braked because the oil contained inside the pump can not be compressed and at this point the rotation of the carrier2is transmitted only to the ring gear12, shaft13, carrier7and output shaft8in which the output rotation speed is increased and the torque decreased because of the overdrive effect taking place at the secondary planetary gear100. Several gradual opening positions of the flow control valve15can be obtained from fully opened to fully closed positions in such a way that the rotation speed and torque of the sun gear9and the output shaft8becomes variable. In other words more speed and less torque is obtained, or high torque and less rotation speed can take place in accordance to the degree of aperture of the flow control valve15which is adjusted by means of a hydraulic regulator that is shown inFIG. 3, and comprises:

an auxiliary hydraulic pump16FIG. 3, that is connected and driven by the output shaft8, is configured to pump oil when the driving wheels17are in motion.

a hydraulic booster18used to drive the flow control valve15when receiving oil pressure from the secondary hydraulic pump16.

a pipe line20FIG. 3which connects the auxiliary hydraulic pump16to the hydraulic booster18; and

a pressure regulator19FIG. 3derived from the pipe line20to drain the excessive oil provided from the secondary hydraulic pump16in correspondence to the rotation speed of the driving wheels17.

OTHER CONTROLS. As pointed out before, the freewheel4,FIG. 1is connected to the ring gear5of the main planetary gear200to permit said ring gear5to rotate only in the same way as engine does, but a housing21,FIG. 1is provided to place said freewheel4, allowing a free rotation of the ring gear in both ways considering that the brake30is not applied over the housing21. On the other hand if the brake30is applied over the housing21, the ring gear5is immediately stopped in one way and the torque generated at the planetary gear assembly200is transmitted to the output shaft8. Neutral or drive shifting positions takes place depending on the action of the brake30over the housing21. Such arrangement avoids the use of any type of clutch between the drive engine of the vehicle and the transmission.
REVERSE SHIFTER. A typical reverse unit is provided to show an optional way to invert the rotation at the output8FIG. 1using four ordinary bevel gears, connecting said output shaft8to the input gear21of that gear system and braking the carrier22by means of the brake40, so that the output gear23which is connected to the driving wheels then turns in opposite direction. Releasing the brake40, no movement is transmitted, but coupling the output gear23together with the carrier22as a unit, the rotation is kept in the same direction.