WO2009043121A1 - Mechanical transmission device with progressive and retractable drive - Google Patents

Abstract

The invention relates to an automatic mechanical transmission system of the centrifugal type that comprises a rotary transmitting or driving member (1) connected to the driving shaft and a rotary receiving or driven member (3) that is hollow and centred on the driving shaft of the driving member and has a curved inner wall (4) such that the driving member (1) is contained in the driven member (3), the driving member (1) including a plurality of housings (2) in each of which is provided a free roller (2A) capable of retraction into its housing (2), characterised in that the system is configured so that, when the driving member (1) is rotated at an increasing speed, the rollers (2A) are in turn, successively and in a cyclic manner urged partially outside their housing (2) by the centrifugal force resulting from said rotation movement and then retract in order to generate a force on said inner wall (4) such that the driven member (3) progressively rotates up to a speed that can reach the rotation speed of the driving member (1).

Description

 3

MECHANICAL TRANSMISSION DEVICE WITH PROGRESSIVE AND RETRACTABLE DRIVE

Object of the invention

The present invention relates to a mechanical transmission device comprising a driving element or receiver and a driving element or motor, both being generally integral with a shaft, the driving of the receiving element being then achieved through the centrifugal force created by the rotation of the shaft integral with the driving element.

The technical field of the invention is that of transmission devices such as centrifugal clutches and automatic transmissions or transmissions by dimmer.

State of the art

[0003] It is known that a clutch device is a ^'temporary coupling between the motor shaft and the output shaft. The transmission is done by adhesion, for example by discs or drum, which allows a progressive loading of the coupling, which avoids jolts or stalling in the case of a heat engine. On motor vehicles, the clutch is essential for the following reasons:

- the engine continues to run (idling) even when the vehicle is stationary;

- The clutch allows the change of gear ratio. In general, the clutch control, whether mechanical, hydraulic or electrical, is voluntary.

In particular, in the field of automatic transmission of self-propelled vehicles such as mopeds or RC models, and in the field of devices normally disengaged for safety reasons, such as lawnmowers and tillers, there are known commands centrifugal clutch. In this case, the command is not voluntary but autonomous, induced by the acceleration of the engine.

For example, in mopeds, we use a simple device similar to drum brakes (see Figure 1). On a plate 1, integral with the axis of a shaft driven by the motor, are fixed a series of pads mounted on 2A hinges articulated and each retained by a calibrated spring 6. The whole is installed at the inside the clutch bell 3 integral with the gearbox. When the plate 1 driven by the motor element reaches a determined rotational speed, the centrifugal force generated pushes the weights and their pads against an outer drum 4 by rotating it. Thus the motor is gradually and automatically coupled to the gearbox, allowing the transmission of the movement to the wheel of the vehicle. When the rotational speed decreases below a certain threshold, the ^" return ^" springs 6 take off the runners of the bell and disconnect the motor from the gearbox.The clutch of the transmission is directly linked to the mass of the runners and to the pulling force of the return springs.

In another example proceeding from a similar principle, illustrated in the document FR 2 647 518-A, there is described an automatic mechanical transmission apparatus with a continuous variation of the transmission ratio from a infinite ratio, up to a ratio of less than 1/1, of the type using centrifugal forces, comprising a driven plate carrying a continuous circular track, eccentric with respect to the common axis of the driving and driven shafts, and rollers which roll within the circular track, being rotatably mounted about respective longitudinal axes, each of these rollers being carried by a link connected to a hinge pin on the driving hub. This device is characterized in that each rod carrying a roller is articulated on the outer portion of a feeder which is itself hinged to the integral hub of the drive shaft.

Still in the case of motorcycles or in certain models of automatic cars with gearboxes with continuous reports, the drive transmission is known, coupled to a centrifugal clutch as described above. A speed variator consists of two pulleys, a driving pulley 14 and a driven pulley 15, the grooves are variable gauge, connected by a belt 13. Depending on I ¹ web spacing of the pulleys, the belt penetrates more or less close to the center, and change the gear ratio accordingly (see Figures 2A and 2B). The driving pulley 14 comprises two half-pulleys, one of which 14A is integral with the motor shaft and the other 14B is slidably mounted longitudinally on the motor shaft. Rollers 17 are interposed between the side of the movable half-pulley 14B and a cover 14C integral with the drive shaft and serving as a guide for the rollers 17. When the engine is stopped, the two half-pulleys 14A, 14B are open. at the maximum and the belt .13 is at the bottom of the groove created by the two half-pulleys. When the motor is rotating, the centrifugal force created on the rollers 17 by rotation pushes the latter outwardly by forcing the movable half-pulley 14B to approach the fixed 14A. As the speed of the motor shaft increases, the centrifugal force forces the rollers further and further outwards, which increases the thrust on the half-pulleys which come closer together and which forces the belt to travel a diameter always higher. The receiving pulley 15 comprises a movable half-pulley 15A and a fixed half-pulley 15B. A spring 16 keeps tight the half-pulleys, which counteracts the thrust of the rollers of the drive pulley and ensures good tension of the belt. In Figure 2A, which corresponds to the minimum engine speed or idle, the driving pulley 14 is open to the maximum and the centrifugal clutch is uncoupled because the centrifugal force at this speed is too low to contact the pads of friction with the clutch bell. When the engine accelerates, the rotational speed becomes sufficient for the centrifugal force to move the clutch shoes and put the friction pads 2A against the clutch housing 3, thereby causing it to rotate. At this moment, the centrifugal force is still insufficient to move the rollers 17 of the variator. The gear ratio remains minimal (equivalent to the first gear ratio) and the vehicle starts (not shown). At mid-speed (not shown), the speed of rotation becomes sufficient for the centrifugal force pushes the rollers 17 of the drive towards its periphery, which pushes the movable half-pulley 14B and narrows the gap of the groove of the. driving pulley 14. The diameter traveled by the belt 13 at the driving pulley 14 increases and, since the belt 13 n'.est not extensible, it then clears the receiving mobile half-pulley 15A while compressing the spring 16. The transmission ratio is now higher (equivalent of the 3 ^rd or 4 ^th report). In Figure 2B, which corresponds to the full speed situation, we see that the rollers 17 are now wedged at the periphery of the variator and the movable half-pulley 14B is completely pushed against the fixed half-pulley 14A. The belt 13 is at its largest diameter on the drive pulley 14 and therefore at the bottom of the groove of the receiving pulley 15, the spring 16 being compressed to the maximum. The transmission ratio is maximum (equivalent of the 5 ^th report). If we now cut the gas, the opposite process is triggered. The speed of the motor shaft is reduced, the rollers down and widen the throat of the drive pulley. The belt back down into the groove thereof and back to the side of the receiving pulley by releasing the compression spring. The process thus continues until the speed of rotation of the receiving pulley is no longer sufficient to keep the clutch pads in contact with the bell. The system then goes into neutral and the vehicle, if it is not stopped, is coasting. [0015] Finally, according to U.S. Patent US-A-5501310 discloses a clutch ^system for multi motorcycle for transmitting power from a crankshaft to a transmission shaft. One of the friction discs is provided with a machined serration in its radial inner surface. The originality of the system lies in the fact that the clutch hub comprises a plate having retractable gear teeth which engage in the corresponding teeth of the aforementioned serration, during the rotation of the motor hub, under the effect centrifugal force. The serration is designed to allow the coupling of the two parts only in one of the two directions of rotation.

Goals of the invention

The present invention aims to provide a solution to overcome the systems of the state of the art.

In particular, the invention aims to provide automatic transmission systems, very simple and very flexible and therefore elongated life.

In particular, the invention aims to provide safety braking systems for decoupling the motor element from the receiving element, in case of emergency or abnormal situation at the receiving element. .

Main features of the invention [0019] A first aspect of the present invention relates to an automatic mechanical transmission system, centrifugal type, that is to say whose control is induced by the variation of a rotational speed of a motor shaft, comprising a driving rotary element or motor integral with the drive shaft and a hollow driven or receiving rotary element, centered on the driving shaft of the driving element and having a curved inner wall, in such a way that the driving element is contained in the driven element, the driving element comprising a plurality of housings in each of which is disposed a free and retractable roller in its housing, characterized in that the system is configured so that, when the driving element is rotated at increasing speed, the rollers, in turn, successively, and cyclically, are partially pushed out of their housing by the centrifugal force resulting from this rotational movement and then retract, so as to create a force on said inner wall such that the driven element progressively rotates up to at a speed which can reach the rotational speed of the driving member.

Particular embodiments of the invention further comprise in combination one or more of the following features:

the distance between the inner wall of the driven element and the axis of rotation of the driving element is variable;

said curved inner wall of the driven element is smooth or devoid of indentation and of circular eccentric, oval, elliptical, pseudotriangular or wave section;

- the rollers are cylindrical, round, oval or in another form ^elongated; the housings have a shape adapted to that of the rollers and a radial axis;

the driving element and the driven element are essentially cylindrical and of the same axis;

the inner wall of the driven element is cylindrical;

the number of rollers is at least two and preferably between 2 and 10; however, in the case of large rotors, the number of rollers may be greater than 10; the system comprises axial lateral retaining flanges and centering of the driving element and the receiving element on the same axis; ^; the rollers have an axial width greater than the axial width of the driving element.

[0021] Other aspects of the present invention relate to the following uses of the automatic mechanical transmission system described above:

- as a clutch element and / or gearbox with continuous gears;

- as a braking element in an elevator;

- as a safety stop element on a conveyor belt.

Brief description of the figures

[0022] Figure 1, already mentioned, shows a centrifugal clutch system according to the state of the art (according to C. Michieletto, http: // tecnomania.interfree.it).

Figures 2A and 2B, already mentioned, show the block diagram of a drive converter according to the state of the art, respectively at the minimum speed and the maximum speed ^s (according to C. Michieletto, http: // tecnomania, interfree, it).

Figures 3 to 6 show schematically a cross-sectional view of various preferred embodiments of the transmission device according to the present invention.

Detailed description of the invention

The system according to the present invention comprises a driving element 1 furnished with openings 2 in which are accommodated movable elements or rollers 2A, the whole being contained in the element to drive 3, which is hollow and whose section of the inner wall 4 has a curved shape. According to the invention, the distance between the inner wall 4 and the axis of rotation O of the driving element 1 is variable. Thus, for example, the driving member 1 may be eccentric with respect to the driven member 3. The aforesaid variation, however, can not be too large so as to prevent the movable members 2A from completely leaving their respective housings 2.

According to variants of the invention, the aforementioned curved shape of the inner wall 4 of the element 3 may be circular eccentric (FIG. 3), elliptical (FIG. 4), pseudo-triangular (FIG. 5) or else wave type (Figure 6).

On the above examples, the rollers 2A are represented in a cylindrical shape of round section, which allows them to move with the freedom to pivot on themselves in the openings 2 of the element 1. The rollers can be lubricated. Thus, by this degree of freedom in rotation, the rollers and their housings are less subject to heterogeneous wear, or can be better lubricated. The rollers may also have an elongated shape that fits their housing which is radial, which allows to give them a linear piston movement. The elongated shape is advantageous because it increases the mass of the rollers relative to the round section, which increases the centrifugal force. A spherical shape is not indicated for the rollers because it would provide only one point of contact.

The aforementioned elements, as such, may still have other forms compatible with the embodiment of the invention, known to those skilled in the art.

Principle of operation

As soon as the driving element 1 starts to rotate about the axis 0, the elements 2A are projected successively and alternately against the inner wall 4 of the element to be driven 3, under the effect of the centrifugal force. As long as the centrifugal force is not sufficient, the elements 2A are pushed in turn by reaction of said wall 4 towards the inside of their respective housings 2. However, when the centrifugal force increases, the elements 2A rely on better and better on the wall of the element 3 and drive it gradually in the rotational movement until it reaches the same speed of rotation as the driving element 1. In fact, the elements 2A act as the teeth of a gear, unlike them, that they are retractable. However, unlike a traditional gear, the crown or rack has no teeth and is smooth. The movement is transmitted further, on the receiving side, from the rotary driven member 3 by any means known to those skilled in the art such as a gear (teeth disposed on the outer surface of the receiving member 3), a belt, etc. It will be noted that the element 3 becomes a braking element for the element 1 if it is immobilized or prevented from rotating faster, or if it is rotated in the opposite direction of the element According to the present invention, the motor elements 1 and receiver 3 are both in the form of a cylinder, one included in the other, whose bases are held by flanges (not shown ), which prevent the rollers from escaping laterally.

Advantageously, the rollers have an axial width greater than the axial width of the motor element 1, which allows a movement of air or lubricant in the gap created between the flanges and the motor element and in the roller housing (cooling role). Tests have shown that the most balanced embodiments are less prone to vibration in operation (same center of gravity for the motor element and the receiving element, lower curvature change of the inner wall of receiving element, etc.).

Areas of application and benefits of the system

The system according to the present invention can be used to replace the gearboxes or clutches of motor vehicles, since the speed of rotation of the receiver element of the aforementioned system continuously changes from 0 to theoretically the speed of rotation of the motor. Such a transmission device makes it possible to better adapt to the driving conditions of a vehicle than in traditional systems. In particular, when stopped, the driven system is blocked, the engine system is braked and can continue to idle.

The system according to the present invention is very simple design, less expensive to produce and maintain and therefore has a much longer life than in the conventional gearbox. It also avoids disadvantages such as oil leaks (hydraulic clutches), friction and wear (belt drives), etc.

The system according to the invention can also be used as a brake, for example in an elevator, or as a safety speed limiter on the conveyor chains. If an obstacle blocks the chain, a disengagement occurs and the engine can continue to turn.

The invention being capable of undergoing various modifications or of presenting itself in alternative forms or variants, the embodiments particular _. discussed here are shown only as examples in the figures. Those skilled in the art will readily understand, however, that the invention is not limited to these particular examples disclosed herein but, on the contrary, covers all modifications, alternatives and equivalents covered by the subject matter of the appended claims.

Claims

1. Automatic mechanical transmission system, centrifugal type, that is to say the control of which is induced by the variation of a rotational speed of a motor shaft, comprising a rotary element driving or motor (1) integral of the driving shaft and a driven rotating element or receiver (3) hollow, centered on the driving shaft of the driving element (1) and having a curved inner wall (4), so that the driving element (1) is contained in the driven element (3), the driving element (1) having a plurality of housings (2) in each of which is disposed a roller (2A) free and retractable in its housing (2), characterized in that the system is configured so that, when the driving element (1) is rotated at increasing speed, the rollers (2A), in turn, successively and cyclically, are pushed partially out of, their housing (2) by the centrifugal force resulting from this slack rotationally and then retract, so as to create a force on said inner wall (4) such that the driven member (3) progressively rotates to a speed which can reach the rotational speed of the coaching element (1). 2. System according to claim 1, characterized in that the distance between the inner wall (4) of the driven element (3) and the axis of rotation of the driving element (1). is variable. 3. System according to claim 1, characterized in that said curved inner wall (4) of the driven element is smooth or devoid of serration and eccentric circular section, oval, elliptical, pseudo-triangular or wave. _4.. System according to claim 1, characterized in that the rollers (2A) are cylindrical, of round, oval or other elongated shape. 5. System according to claim 4, characterized in that the housings (2) have a shape adapted to that of the rollers and a radial axis. 6. System according to claim 1, characterized in that the driving element (1) and the driven element (3) are essentially cylindrical and of the same axis. 7. System according to claim 1, characterized in that the inner wall (4) of the driven member (3) is cylindrical. 8. System according to claim 1, characterized in that the number of rollers (2A) is between 2 and 10. 9. System according to claim 1, characterized in that it comprises axial side retaining flanges and centering of the driving element (1) and the receiving element (3) on the same axis. 10. System according to claim 9, characterized in that the rollers (2A) have an axial width greater than the axial width of the driving element (1). 11. Use of the automatic mechanical transmission system according to any one of claims 1 to 10, as a clutch element and / or continuous ratio gearbox. 12. Use of the automatic mechanical transmission system according to any one of claims 1 to 10, as braking element in an elevator. 13. Use of the automatic mechanical transmission system according to any one of Claims 1 to 10 as a safety stop element on a conveyor belt.