Patent Application
20180326846
This invention is related to the mechanical and automotive technical fields since it concerns a differential system that controls the traction of at least the four wheels of a vehicle.
Differential mechanisms derived from the need to be able to have the wheels of a vehicle turn at a different speed while the vehicle is moving along a curve, and have the said wheels turn at the same speed while the vehicle is moving along a straight line.
The conventional open differential mechanism solved this problem by being initially installed in the forward axle of the vehicle. Subsequently the differential was installed also in the rear axle and later also in a central axle, located between the forward and rear axles. In this way, once all the 3 above mentioned differential mechanisms were installed in the vehicle the result was permanent traction on its 4 wheels, providing permanent traction in its 4 wheels and allowing the vehicle to circulate on surfaces of both low or high adherence.
Subsequently the problem arose that although a vehicle would have 1, 2 or 3 differential mechanisms, if a wheel of the said vehicle skidded then the vehicle would lose traction and would no longer move forward, due to the fact that all of its force would be directed to the skidding wheel; in order to solve this problem differential systems with locking planetary mechanisms were devised, as well as self-locking differential mechanisms which partially or completely solve the problem of losing the entire force of the vehicle on the skidding wheel. However, these systems generate other problems, especially concerning maneuverability and steering. Furthermore, they are not as efficient as desired since the differential mechanisms that lock their planetary gears have the disadvantage of having the 2 wheels of the vehicle to which the force is directed spinning at the same speed, which means that under these conditions the vehicle should only move on low adherence surfaces in order to avoid damaging its power transmission system and to prevent premature wear of tires; additionally, self-locking differential mechanisms have the drawback in some cases of having a slow response, in others of working only when it is detected that a wheel is skidding at a certain speed in relation to the opposite wheel, and in others yet of saving only a small percentage of the force which is lost by the skidding wheel. Finally, most of these systems are based on friction, which represents a loss of energy.
In order to enhance their efficiency, the said differential mechanisms were combined with electronic or hydraulic systems and/or sensors, among others, which resulted in faster response times and a more controlled performance, yet these systems also have drawbacks, such as a higher cost, being heavier and more prone to malfunctions as a consequence of having more parts, components, mechanisms and/or systems; in addition to the fact that these systems also use friction, whether for stopping a wheel of the vehicle or a component of the differential mechanisms, which also results in a loss of energy.
Another of the main problems concerning the above-mentioned conventional differential mechanisms is that in order for them to provide traction to all 4 wheels at least 2 or 3 have to be installed, which results in higher cost and weight.
The technologies mentioned below present some examples of traction systems that control the wheels of a vehicle which include conventional differential mechanisms and a power transmission mechanism:
Patent document U.S. Pat. No. 834,008 describes a vehicle with a combination of two pairs of traction wheels, a chassis which supports an energy supply element, a sectional axle for each pair of wheels supported by the chassis, components for connecting the said sectional axle to the wheels in order to make them turn; a differential mechanism belonging to a pair of wheels and power transmission devices for carrying it between the sectional axles.
Patent document MXPA00005686 describes a system for controlling the transfer of torque in a vehicle that includes a transfer enclosure, as well as an anterior and posterior differential unit. In this system the transfer enclosure automatically transfers the torque between the differential units, while the differential units transfer the torque to their respective wheels; under extreme conditions the system supplies the entire torque to a single traction wheel.
Patent document MX2013011507 refers to a differential mechanism that controls the 4 wheels of a vehicle. This is a more complex mechanism which also has the inconvenient that when the vehicle travels along a curve the said differential mechanism accelerates the front wheel located on the open side of the curve, this results in premature wear of the front tires. Additionally, the power transmission system is subjected to a greater effort and thus this differential mechanism is not suitable for vehicles which usually circulate on highly adherent surfaces.
Patent document U.S. Pat. No. 2,514,071 refers to 3 differential mechanism which work together for transmitting force to the 4 wheels of the vehicle. The problem with this system, in addition to the fact that it is composed of 3 differentials, which results in a higher weight and cost than having a single differential, is that when the front right and rear left wheels, or the front left and rear right wheels skid, the vehicle loses traction.
As for patent document WO8802829 A1, it describes a self-locking differential mechanism which is sensitive to torque known as “Torsen”, which attempts to prevent at all times sudden changes in force and spin velocity, preferably between 2 wheels or between 2 axles of a vehicle. This system has the disadvantage that with the resistance and friction it uses in order to prevent a wheel from spinning out of control, the ratio of force and spin velocity in each wheel or axle is not an optimal ratio, in other words, when a wheel skids the vehicle does not lose all of its traction, but it does lose an important amount of force over the skidding wheel. Additionally, the system generates a constant loss of energy when the vehicle is travelling along a curve, even when none of its wheels are skidding.
Patent document US2010063701 presents a self-locking differential with a viscous coupling device which can link the front and rear axles of a vehicle, providing traction on all 4 wheels. The disadvantage of this system is that the time of response for coupling the said axles is slow and in certain circumstances is not capable of transmitting the necessary force to the axle which has the better traction, resulting in the loss of traction.
For this reason, in order to counter the above-mentioned issues, a differential system was developed that controls the traction of at least the four wheels of a vehicle, depending on the conditions and circumstances of the road on which it is travelling, allowing the vehicle to circulate on surfaces with either low or high adherence without having to change its traction as it is normally done from “4×2” to “4×4” and vice versa; a system which works as a self-locking differential mechanism with an almost immediate time of response, without having to brake any of the wheels of the vehicle or any component of the differential system, which is useful in preventing loss of energy due to friction generated by the brakes; can help the vehicle make tighter turns than usual, allows the vehicle to take a turn at a higher speed with elements that help the driver to reduce the possibility of an understeer, which can be configured so that the vehicle can turn without displacement and which additionally includes several forms of power transmission to the wheels of the vehicle.
The invention in question regards a differential system that controls the traction of the wheels of a vehicle, specifically vehicles which have at least four wheels.
Below are described some of the realizations of the said invention, together with the figures mentioned above. These realizations are to be taken by way of example and should therefore not be construed as a limitation of the invention in question.
The differential system that controls the traction of at least the four wheels of a vehicle, which is the object of this invention, consists in a first differential mechanism (1) which can be connected between the free extremities of the axles (3 or 6) of the wheels (4 or 7) of the vehicle; where the free extremities of the axles (3 or 6) connect to the planetary gears of the said differential mechanism (1).
A preferred method is to mount the differential mechanism (1) between the free extremities of the axles (3) of the rear wheels (4) of the vehicle.
The first differential mechanism (1) can be: an open differential mechanism, a self-locking differential mechanism, or a manual and/or automatically locking differential mechanism. The self-locking differential mechanism in turn can be: a limited-slip differential (Viscous or Ferguson and mechanical self-locking); a torque-sensitive differential (Torsen); or a controlled-slip differential (multi-plate clutch).
At least one power transmission mechanism is provided for each side of the first differential mechanism (1); where the driving element (8) of the power transmission mechanism connects to the corresponding axle (3 or 6) linked to the differential mechanism (1) in order to provide the said driving element (8) with driving movement; and the driven element (10) of the power transmission mechanism connects to the axle without differential mechanism (1) of the wheels (4 and 7) of the same side in order to transmit the power to those wheels, through the transmission medium (9) of the said power transmission mechanism.
A preferred variation of the invention in question is that the driving (8) and driven (10) elements of the power transmission mechanism are: indented wheels, gears, pinions and/or pulleys; and the transmission medium (9) is selected from the following group: indented wheels, gearset, driveshafts, axles, pinions, chains, pulleys, belts, straps, mechanical joints, mechanical ball joints and/or articulated joints.
The differential system of this invention includes a freewheel unit (5) placed in the trajectory of the power transmission that goes from the differential mechanism (1) toward its corresponding front wheel (7). This freewheel unit (5) can include, at least, a freewheel, depending on the required torque and/or its performance.
It is worth mentioning that for the purposes of this invention, the term “freewheel” refers to any mechanism that allows an axle, part, component, mechanism and/or device to spin freely in one direction and to be geared, assembled, coupled and/or joined when spinning in the opposite direction, such as, for example: a clutch bearing, a free pinion, a freewheel, an indented freewheel, among others.
Another realization of the invention consists in the fact that the driving element (8), the driven element (10) and/or the transmission medium (9), all have different diameters so as to reduce the spin velocity of the force as it enters the freewheel unit (5), with respect to the spin velocity of the force as it leaves the said freewheel unit (5).
An additional modality of the invention in question is that the freewheel unit includes: at least, a freewheel (5′) for transmitting force as the vehicle moves forward; at least, a freewheel (5″) that transmits the force when the vehicle moves backwards; and a selector mechanism which select one or another of the freewheels (5′ or 5″), depending on the direction in which the vehicle is moving. Where the said freewheels (5′ and 5″) have an indented exterior surface.
An innovation of the selector mechanism is that it is composed by: a sliding coupler (17) that has an internal and/or external adaptor (18′) on one of its extremities which houses a medium for the entrance or exit of force (21); another extremity indented on the inside (18), to which is coupled the exterior surface of one or another of the freewheels (5′ or 5″), which are mounted on a force input or output axle (23); and an external duct (24), located preferably on one of its extremities; a control arm (19) that is inserted in the external duct (24) of the coupler (17) in order to move it from one freewheel to another (5′ or 5″); and a driving medium (20) for moving the control arm (19).
The internal and/or external adaptation (18′) can be, at least: an indented surface, a groove, a plane and/or a protrusion, among others.
It is worth mentioning that the medium for displacing the control arm is a device which is: mechanical, electrical, electronic, pneumatic, hydraulic, electromagnetic, etc.; and/or the combinations between them.
The force input or output medium (21) of the selector mechanism can consist of a pinion mounted on an axle that transmits the force; and in which the medium for displacing the control arm (19) can be a device which is: mechanical, electrical, electronic, pneumatic, hydraulic, electromagnetic, and so on.
The differential system that controls the traction of at least the four wheels of a vehicle also includes, at least, a braking system for braking the wheels of the vehicle. This braking system is selected from the following group: a brake that brakes the four wheels (4 and 7) at the same time; a brake that brakes the two front wheels (7) at the same time; a brake that brakes the two rear wheels (4) at the same time; a brake that brakes each front wheel (7) independently; a brake that brakes each rear wheel (4) independently; and/or the combinations between them; in which the said braking system can be operated with a pedal, a handle and/or the turn of the steering wheel of the vehicle.
Another innovation of the differential system of the invention in question consists in the fact that it includes as well a locking and unlocking mechanism (11) on each freewheel unit (5), for locking or unlocking it; this locking and unlocking mechanism (11) can be: a brake, a clutch, or a device which is: mechanical, electrical, electronic, pneumatic, hydraulic, electromagnetic, etc.; and/or the combinations between them.
Another innovation of this invention consists in the fact that the power transmission mechanism includes a switch (12) for connecting and disconnecting the transmission of force directed to its corresponding front wheel (7); this switch (12) can be: a clutch, a mechanism for disconnecting axles; and/or components of the power transmission mechanism.
Another realization of the differential system in this invention is when the first differential mechanism (1) is a differential mechanism which is lockable both manually and automatically; especially when it is an open differential mechanism with a mechanism for locking and unlocking its planetary gears (1′). This first open and lockable differential mechanism (1′), includes as well a switch (12) placed on at least one of its planetary gears, in order to connect and disconnect the transmission of force of the said planetary. This is with the purpose of allowing the differential system of this invention to incorporate a mechanism for inverting the spin of the wheels (4 y 7) on one side, with respect to the wheels (4 y 7) on the other side. This mechanism for inverting the spin of the wheels can be a second differential mechanism or a transfer case.
A brake is included as well for braking at least one of the components of the said mechanism that inverts the spin of the wheels.
A feature of this invention consists in the fact that the second differential mechanism is an open differential mechanism (2), whose force input takes place through one of its planetary gears and force output through the other planetary, and is mounted between the free axles (6) of the front wheels (7) of the vehicle; and the brake for blocking the pinion (13) of the said open differential mechanism (2), is preferably a disc brake (14).
Another feature of this invention consists in the fact that the crown and pinion of the front open differential mechanism (2) are removed, and the brake for braking the satellite gearbox of the said front open differential (2) is: a disc brake (15).
Another feature of this invention consists in the fact that the crown and pinion of the front open differential mechanism (2) are removed and a switch (12) is connected to one of the sides of the said front differential mechanism (2), in order to connect and disconnect its transmission of force, when its satellite gearbox is stationary.
Another innovative feature of this invention is that the differential system includes as well: an axle (26) for transmitting the force from the motor (25) of the vehicle to a satellite of the front open differential mechanism (2); a first switch (12) for connecting and disconnecting the transmission of force that goes from the motor (25) to the first differential mechanism (1), in this case the first differential mechanism (1) has no switches (12) on its sides; and a second switch (12′) for connecting and disconnecting the transmission of force that goes from the motor (25) to the front open differential mechanism (2).
An example of the realization of the transfer case is when it includes: a longitudinal axle (28) that transmits the force of the motor (25) of the vehicle toward the first differential mechanism (1); at least a first conical gear (29) that is inserted axially to the longitudinal axle (28); at least a second conical gear (30) that connects perpendicularly to the first conical gear (29); a transverse axle (31) that supports the second conical gear (30), in which the said transverse axle is connected to its corresponding power transmission mechanism and is supported on the side walls (27) of the transfer case; a switch (12) placed on the transverse axle (31), for connecting and disconnecting the transmission of force directed to its corresponding power transmission mechanism; and another switch (12) placed on at least one of the components that transmit the force that goes from the first conical gear (29) to the first differential mechanism (1).
An additional feature of the differential system is that it includes a brake (32) placed on at least one of the components that transmit the force going from the last above-mentioned switch (12) to the first differential mechanism (1).
The invention therefore also refers to a vehicle that includes a differential system that controls the transmission of at least the four wheels of a vehicle, in accordance with the differential system described in this invention. This vehicle can be a car, an all-terrain vehicle, a utility vehicle, a cargo transport vehicle, or machinery with 4 or more wheels, among others.
With the simple fact of adding a freewheel unit (5) on each side of a differential system, the advantage is obtained of transforming the conventional differential system into a self-locking system and thus making it possible for the vehicle to circulate with a better degree of traction on surfaces of medium and low adherence, such as: dirt roads, mud, sludge, loose gravel, sand, wet pavement, snow, etc.; considering that one of the main advantages of the differential system in question consists in the fact that it allows the vehicle to circulate with traction on its 4 wheels on surfaces with high adherence, such as dry pavement, without the need to change from traction on its 4 wheels (performing as 4×4) to traction on its 2 rear wheels (performing as 4×2) and vice versa, as is usually the case with vehicles today. In addition to the fact that in this way the vehicle gains maneuverability, has better steering and is capable of taking tighter turns, considerably reducing the effort and excessive wear of both the tires and the transmission system, as is usually the case with vehicles that have a positive differential mechanism between the axles of their rear wheels which make the rear wheels to spin always at the same speed and in the same direction, as in the vast majority of current ATV (All Terrain Vehicle) and UTV (Utility Task Vehicle) vehicles, as well as in vehicles which do not have a central differential mechanism central and have traction activated on all four wheels.
The differential system of the invention in question has the above-mentioned self-locking mechanism since while the vehicle is moving in a straight line it will normally have traction on all four of its wheels (performing as 4×4); when the vehicle circulates on a curve, it will normally have traction on its two rear wheels (performing as 4×2), allowing the two front wheels to spin freely depending on how many spins each front wheel needs to take; and when any or both of the rear wheels of the vehicle lose traction, at that moment, in a mechanical and automatic way through the freewheel units (5), traction is transmitted to the respective front wheel or wheels of the vehicle (performing as 4×3 or 4×4), thus self-locking the out of control spin of the rear wheels that have lost traction.
The differential system of this invention provides the vehicle with traction at least on two of its wheels (performing as 4×2 in three different ways), either on its two rear wheels, on the two wheels on the left side, or on the two wheels on the right side; usually it will be the two rear wheels to have traction.
It is important to mention that the differential system of the invention provides the user with greater and better control of the vehicle, since by having brakes that operate independently on at least two of the wheels, the vehicle can turn by pivoting on the wheel that is braking, therefore when the brakes are used independently, in addition to braking the vehicle, they function as “Directional Brakes” with which it is possible to give considerably tighter turns than usual, and which reduce the possibility of an “understeer”, depending however on the driving skills of the user.
Another of the main advantages of the differential system in question consists in the fact that it provides the user with “Total Control” of his vehicle, since in addition to driving, maneuvering, accelerating and/or braking his vehicle, he also has control on the distribution of the force being sent to all the wheels of the vehicle, in other words the user can decide at any moment to which wheels he wishes to transmit the force to, whether he transmits the force: only to the rear wheels, partially or totally to the wheels on the left side of the vehicle, partially or totally to the wheels on the right side of the vehicle, or to the all four wheels at the same time; or that when the force is transmitted mechanically and automatically to the rear wheels, force is also transmitted to the corresponding front wheel of the rear wheel or wheels that lose traction; the user can also decide whether the wheels on the left side of the vehicle spin in the opposite direction and at the same or different speed than the wheels of the right side of the vehicle; or if each rear wheel spins at the same or at a different speed than its corresponding front wheel; depending on how the differential system of the invention is configured.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/MX2015/000143 | 11/3/2015 | WO | 00 |
