WO2014096598A1

WO2014096598A1 - Torsional vibration damping transmission element

Info

Publication number: WO2014096598A1
Application number: PCT/FR2013/052891
Authority: WO
Inventors: Philippe MERCKX; Xavier DESCOTTES
Original assignee: Peugeot Citroen Automobiles Sa
Priority date: 2012-12-20
Filing date: 2013-11-28
Publication date: 2014-06-26
Also published as: CN105102854A; FR3000151A1; EP2935937A1; CN105102854B; FR3000151B1

Abstract

The present invention relates to a torsional vibration damping transmission element between a drive shaft and a driven shaft, this element limiting the vibrational excitation of the drive shaft transmitted to the driven shaft and reducing the dynamic forces passing through the element transmitting movement between the two shafts subjected to a rotational movement. The transmission element (1) is interposed between a drive shaft and a driven shaft transmitting rotational movement from the drive shaft to the driven shaft and is provided with a seismic mass (9, 9a) consisting of two portions, an elastomeric member (10) being interposed between the two portions, the seismic mass (9, 9a) being calculated to increase the inertia value of the transmission element (1) without a seismic mass (9, 9a) by a factor of between 2 and 5.

Description

TORSION VIBRATION DAMPER TRANSMITTING ELEMENT

The present invention relates to a torsion vibration damping transmission element between a driving shaft and a driven shaft, this element for limiting the vibrational excitation of the drive shaft transmitted to the driven shaft and to reduce the dynamic forces passing through the motion transmission element between the two shafts subjected to a rotational movement. By transmission element is meant any mechanical element, for example pulley or pinion, ensuring the transmission in a complete kinematic chain, this transmission element may or may not be part of one of the leading or driven shafts.

The present invention finds a particularly advantageous but non-limiting application in the field of motor vehicles between a drive shaft and a driven shaft for better mechanical strength of the two shafts and enhanced acoustic and vibration benefits. For example, the rotating drive shaft may be a crankshaft of a heat engine and the shaft drives a balancer shaft or a drive shaft of mechanical accessories, including a camshaft.

In the automotive field, the present invention can also be applied, without limitation, to the connection between two intake and exhaust cam shafts, between two balancing shafts or between two shafts. gearbox.

In what follows, it will be taken as an application of the invention the drive of a shaft driven by a drive shaft shown by a crankshaft, this being only illustrative. Thus, in some internal combustion heat engines, it is intended to carry out the driving of a secondary shaft, for example a balancing shaft, a drive shaft of secondary accessories of the pump, electric generator or alternator type, a gear meshing system.

Such mechanical coupling systems by meshing are very sensitive to vibratory excitations of the drive shaft in particular torsional vibrations from the drive shaft. Inter-tooth shocks driving shaft with driven shaft, where appropriate with a transmission element interposed between them, locally create areas highly mechanically stressed and generate mechanical dirty noises that may become unacceptable for the operation of an engine in a vehicle automotive for example or other mechanical uses. There are, to reduce or eliminate these mechanical shocks, clearance play systems, for example a spring system with a pinion or damping systems, for example a mechanical friction system or by use of elastomers providing decoupling and damping. These systems are highly stressed and very sensitive to the excitation level of the driving shaft on the one hand, and to the shape and level of the resisting torque of the driven shaft on the other hand.

These gaming catch-up systems have limitations. For some severe uses, acyclic pairs of trees are very high: traditional catch-up or cushioning systems are no longer efficient or complex and costly. The pre-load torques of the play-catching systems become important, which results in significant friction losses and meshing siren noises, due to a very great excitation of the gear teeth.

FR-A-2 744 780 discloses a pulley comprising a hub that can be wedged on a shaft and a rim arranged for a driving contact with a belt, in which the rim is mounted to rotate around a central hub portion being connected to a peripheral hub portion by an elastomeric element acting as a decoupling element. It should be noted that the decoupling element can be made by a spring or a set of springs. An embodiment in this document shows an elastomeric decoupling element. The decoupling element comprises an elastomer ring and the hub of the pulley is surrounded by a seismic element connected to said hub by an elastomeric damping element ensuring torsional vibration damping, the rim being connected to said seismic element by via the elastomer ring. The elastomeric ring is disposed between the lower part of the seismic element and the driving surface of the pulley.

The seismic element described in this document, because of its position, does not have sufficient inertia to reduce the dynamic torque transmitted by the pulley. The position of the elastomeric ring between the lower part of the seismic element and the driving surface of the pulley does not make it possible to limit the acyclisms transmitted to the pulley.

Therefore, the problem underlying the invention is, in a mechanical system comprising a driving shaft and a driven shaft a transmission element being interposed between the two shafts, to provide for this transmission element a shock absorber of torsion vibrations from the drive shaft and to reduce the excitation source of vibratory stresses at the coupling of the transmission element coupling the driven shaft with the driving shaft.

[001 1] To achieve this objective, it is provided according to the invention a transmission element interposed between a driving shaft and a driven shaft transmitting the rotary movement of the shaft leading to the driven shaft, characterized in that the transmission element is provided with a seismic mass composed of two parts, an elastomeric element being interposed between the two parts, the seismic mass being calculated to increase the inertia value of the transmission element without seismic mass by a factor between 2 and 5.

The usual design of the seismic mass leads to an inertial value of the seismic mass about 1, 5 times smaller than the minimum value whose definition is given below. The usual sizing is done in order to ensure the durability of the crankshaft. From this point of view, the choice of the invention corresponds to an oversizing of the seismic mass, if only durability was considered. Indeed, the idea is not only to dampen the torsional vibrations of the hub of the crankshaft pulley torsional vibration damping (also called AVT pulley) attached to the crankshaft but to add a function of reducing contact forces by dimensioning the seismic mass in a particular way.

It should be noted that the word inserted must be taken in a broad sense. The transmission element may for example be part of the driving shaft or the driven shaft or be independent of the driving and driven shafts.

Advantageously, the elastomeric element is in the form of a ring, the parts of the seismic mass being superimposed on one another forming an inner portion and an outer portion.

Advantageously, at least the outer portion of the seismic mass projects laterally from the transmission element.

[0016] Advantageously, the transmission element is a pinion.

Advantageously, the transmission element is a pulley having a hub connecting it to the driving shaft and comprising at least one flange having an outer portion forming a plate carrying at least one external path for receiving a means of belt or chain type drive, the seismic mass being disposed at the end of the pulley opposite to that having the hub, the inner and outer portions being in the form of a respective ring. Advantageously, two flanges are provided, each with an external path for receiving a respective drive means of the belt or chain type.

Advantageously, there is provided a second elastomer disposed in at least one external path.

The present invention also relates to a transmission assembly comprising a drive shaft and a driven shaft, characterized in that such a transmission element is interposed between the drive shaft and the driven shaft.

Advantageously, the driving shaft is the crankshaft of a heat engine, the transmission element being a crankshaft pulley, a drive means of the belt or chain type connecting the pulley to an element integral with the shaft. conducted.

Advantageously, the assembly has a flywheel and the inertia value seismic mass of the seismic mass of the pulley is calculated according to the following formula: ## EQU1 ##

¹ mass ½%%%%%%% ^{Λ Λ}

Where the rotating assembly is the inertia value of the set off the flywheel and is at least greater than the ratio of the number of cylinders of the engine that multiplies 2/3.

Other features, objects and advantages of the present invention will appear on reading the detailed description which follows and with reference to the accompanying drawings given by way of non-limiting examples and in which:

FIG. 1 is a schematic representation of a longitudinal central section of the crankshaft, one end of which is connected to a crankshaft pulley according to the state of the art,

FIG. 2 is an enlarged schematic representation with respect to FIG. 1 showing a section of a pulley according to the state of the art,

FIG. 3 is a diagrammatic representation of a half section of a pulley according to an embodiment of the present invention, this pulley having an elastomer element and a seismic mass.

In what follows, it will be taken as transmission element a pulley connected to one end of the crankshaft, the crankshaft illustrating a driving shaft. This is not limiting and the transmission element can be any other being interposed between a drive shaft and a driven shaft.

As shown in Figure 1, a pulley 1a is connected to the end 2a of a crankshaft 2 vis-à-vis its hub 3 through the opening of the facade 4 of casing. The end of the hub 3 of the pulley 1a is inserted inside the corresponding end 2a of the crankshaft 2 to be secured to said end 2a, this by any means, for example screw and thread, forging, riveting or other.

At its end 2a facing the pulley 1a, the crankshaft 2 can be maintained by the last bearing 1 1 crankshaft of a series of crankshaft bearings internal to the housing, the last bearing 1 1 of crankshaft being closest to the crankshaft end 2a of the bearings of the series. The last bearing 1 1 crankshaft can be associated with a second bearing for the support of the hub 3 of the pulley 1a but this is not mandatory.

Many other embodiments of such a pulley and crankshaft assembly are also possible. For example, the pulley 1 may be closer to the crankshaft than shown in FIG. In addition, the hub 3 may take a smaller shape than that shown in Figure 1 being in the form of a rod. On the other hand, the crankshaft 2, at its end 2a can carry at least one drive element of at least one camshaft for the opening or closing of the valves of the associated engine.

Referring to Figures 2 and 3, Figure 2 showing a pulley 1a according to the state of the art as shown in Figure 1 and Figure 3 showing a pulley 1 according to the present invention, pulleys 1a and 1 respectively of Figures 2 and 3 together have common features.

In these figures, the pulleys 1, 1a illustrating a transmission element comprise a first hollow central portion 3a for receiving the hub referenced 3 in Figure 1 connecting them to the crankshaft. The pulleys 1, 1a have a first flange 7 or flange and a second flange 8. The first flange 7 has an outer portion forming a first plate extending between the two flanges 7 and 8 and the second flange 8 has an outer portion forming a second plate extending for the pulley 1 a of the state of the art to the end of the pulley opposite to that carrying the hub referenced 3 in FIG. 1, the plates being substantially perpendicular to the flanges 7 and 8. It is also possible to provide pulleys 1 and 1a only a tray and a flange.

Each first and second plate respectively carries a first or second path 5, 6 external receiving or rim of a respective drive means of the belt or chain type, these paths 5, 6 having ribs cooperating with the means of associated training. The drive means of the belt or chain type passing through a path 5, 6 respectively can transmit the rotational movement of the pulley 1, 1a to one or more accessory receiving members such as an alternator, a pump to water, an air conditioning compressor and / or a hydraulic power steering compressor.

Advantageously, the belt-type drive means or chain passing through the second path 6 farthest from the crankshaft which is wider than the first path 5 drives an alternator, an alternator-starter or an electric machine. As shown only in Figure 2 but also applicable to the pulley 1 according to the present invention shown in Figure 3, at least one elastomeric ring 12 may be disposed under the second path 6 in the second flange 8. It may be even for the first path 5 although not illustrated in FIGS. 2 and 3.

According to the present invention, the pulley 1 illustrating the transmission element carries a seismic mass 9, 9a and at least one elastomeric element 10 advantageously in the form of a ring. The seismic mass 9, 9a is in two parts, the elastomeric element 10 in the form of a ring being interposed between the two parts of the mass. The seismic mass 9, 9a is calculated to increase the inertia value of the transmission element 1 without seismic mass 9, 9a by a factor of between 2 and 5.

The seismic mass 9, 9a may be disposed in the pulley 1 after the second plate of the second flange 8 carrying the outer path 6 for the drive means of the belt or chain type. The seismic mass 9, 9a therefore forms the end of the pulley opposite to that facing the crankshaft. An outermost part 9a of the seismic mass 9, 9a is superimposed above the other part 9a. At least this superimposed portion 9a can protrude laterally from the pulley 1.

The two parts of the seismic mass 9, 9a are advantageously in the form of a respective ring, the rings being concentric and the ring formed by the outermost part 9a of the mass 9, 9a surrounding the formed ring. by the other part 9, the innermost.

To be effective, the torsional vibration damper is advantageously positioned axially in an area of high angular amplitude and the torsional vibration damper is keyed on the critical frequencies in terms of mechanical stress, mainly shocks.

For a heat engine, the crankshaft acting as a driving shaft, a crankshaft pulley torsional vibration damping or AVT, shown in Figures 1 and 2 under the reference 1a is commonly used to ensure the mechanical strength of the Crankshaft at high speeds. In the context of the present invention, this pulley AVT is resized and strongly modified to widen its field of effectiveness and reduce the acyclic couples transmitted to the meshing system of the driven shaft, not shown in the figures.

It may be advantageous to use a double torsional vibration damper consisting of a stage to limit the oscillations of torsional vibrations of the crankshaft at high speeds, this stage being dedicated to the mechanical strength and a stage to limit the twisting oscillations of the meshing of the secondary shaft, that is to say the reduction of shocks and mechanical noise.

An AVT pulley of the state of the art referenced 1 to Figures 1 and 2 has the main role of breaking the first mode of torsion of the crankshaft. This AVT pulley is dimensioned to dampen only the torsional vibrations of the elements of the mechanical assembly such as the flywheel, the crankshaft, the pulley or pulleys related to the distribution drives and accessories and other elements fixed on the crankshaft.

[0039] A torsional vibration is a magnitude of length. It is measured in angular displacement or its time derivatives that are angular velocities and accelerations. These angular displacements induce deformation stresses in the crankshaft which, if they are too large, will damage the transmission assembly, or even go until it breaks. This first mode can cause the break in mechanical fatigue of the crankshaft and generates dirty noises.

In addition to this basic function which is maintained, the drumming power of the pulley according to the present invention and referenced 1 in Figure 3 is used to reduce the excitation source of the grit generating mechanism at the coupling with the led tree. Increasing the inertia by a factor of 2 to 5 due to the addition of the mass of inertia 9, 9a and the adjusted setting of the pulley 1 makes it possible to reduce the dynamic torque passing between the driving shafts and conducted.

The inertia of the pulley 1 according to the present invention, multiplied by a factor ranging from 2 to 5 by the presence of the mass of inertia 9, 9a is, reduces the normal contact force when a denture shock. The torsional stiffness of the elastomer 10 between the two parts of the mass of inertia 9, 9a can be advantageously also specifically predetermined in order to reduce this contact force while maintaining the torsional vibration damping function of the pulley original. There is indeed a relationship between the reduction of the force value and the values of inertia of the mass of inertia 9, 9a and elastomer stiffness 10.

Thus, for a considered engine, the value of the rotational inertia of the rotating transmission assembly, out of the ring of the pulley 1 and out of the flywheel, can be used for the determining the value of the seismic mass 9, 9a to be taken into account for the pulley 1 according to the present invention according to the following formula:

Where a has the minimum value the ratio of the number of cylinders of the engine that multiplies 2/3 i 2

o ^u A¾mirs- of cylœdrss "3

Such a pulley with mass of inertia and elastomer associated with the mass of inertia reduces the noise of shot, hammering and siren meshing of the balancer shaft.

The characteristics stated in association with a crankshaft pulley can also be applied to other types of transmission elements between a drive shaft and a driven shaft, for example gears, the transmission then being direct between the driving shaft. and driven shaft by not requiring a drive means of the belt or chain type as in the case of a pulley.

The invention is not limited to the described and illustrated embodiments which have been given as examples.

Claims

1. Transmission element (1) interposed between a driving shaft (2) and a driven shaft transmitting the rotary movement of the driving shaft (2) to the driven shaft, characterized in that the transmission element (1) is provided with a seismic mass (9, 9a) composed of two parts, an elastomeric element (10) being interposed between the two parts, the seismic mass (9, 9a) being calculated to increase the inertia value of the element of transmission (1) without seismic mass (9, 9a) by a factor of between 2 and 5.

2. Transmission element (1) according to claim 1, wherein the elastomeric element (10) is in the form of a ring, the parts of the seismic mass (9, 9a) being superimposed on one another forming an inner portion (9) and an outer portion (9a).

3. Transmission element (1) according to claim 2, wherein at least the outer portion (9a) of the seismic mass (9, 9a) projects laterally from the transmission element (1).

4. Transmission element (1) according to any one of the preceding claims, which is a pinion.

5. Transmission element (1) according to any one of claims 1 to 4, which is a pulley (1) having a hub (3) connecting it to the drive shaft (2) and comprising at least one flange (7). 8) having an outer portion forming a plate carrying an external path (5, 6) for receiving a belt-type or chain-type drive means, the seismic mass (9, 9a) being disposed at the end of the belt pulley (1) opposite to that having the hub (3), the inner (9) and outer (9a) being in the form of a respective ring.

Transmission element (1) according to claim 5, for which two flanges (7, 8) are provided, each with an external path (5, 6) for receiving a respective belt-type drive means or chain.

7. transmission element (1) according to claim 5 or 6, wherein there is provided a second elastomer (13) disposed in at least one external path (5, 6).

8. Transmission assembly (1) comprising a drive shaft (2) and a driven shaft, characterized in that a transmission element (1) according to any one of the preceding claims is interposed between the drive shaft (2) and the led tree.

Transmission assembly (1) according to claim 8, wherein the driving shaft is the crankshaft (2) of a heat engine, the transmission element being a pulley (1). crankshaft, a drive means of the belt or chain type connecting the pulley (1) to an element integral with the driven shaft.

10. transmission assembly (1) according to claim 9, which has a flywheel and for which the inertia value of the seismic mass (9, 9a) of the pulley (1) is calculated according to the following formula: