RO134054A2 - Circular transmission wheel with uneven mass angular distribution and engine comprising the same - Google Patents

Abstract

The invention relates to a circular transmission wheel with uneven mass angular distribution and to an engine comprising the same. According to the invention, the wheel has two flanks (15) separated by an edge (19), some teeth (16 and 16a) the points of which pass through a circle, a central slot (13) allowing its mounting on the first end of a crankshaft (4), two particular portions (11 and 12) arranged, each, separately, in two given angular sectors (17 and 18), where the two particular portions (11 and 12) are formed through some through holes opening on each flank (15). The engine, as claimed by the invention, comprises a drive shaft (4), a transmission wheel (10(and a mobile part (7) placed along with the transmission wheel (10), so that the transmission wheel (10) drives the mobile part (7) into motion.

Description

Circular drive wheel with unequal angular mass distribution and motor comprising such a wheel

Description

The present invention relates to the field of engines, in particular heat engines.

More specifically, the present invention relates to a wheel for transmitting motion, such as a toothed wheel or a pulley, intended to be driven by a shaft so that, by its edge or tread, it drives a moving part. Specifically, this drive wheel is that of a transmission system of an engine.

For example, in a heat engine, the cylinders drive a crankshaft which forms the drive shaft whose rotation, by means of the gearbox, is transmitted to the wheels of the vehicle resting on the road. Generally, a drive wheel is mounted on the crankshaft head and drives a belt or drive chain, which rotates the motor camshaft.

One of the problems that arises is that the crankshaft does not have a constant rotation, but has angular distances from the axis of rotation that form periodic vibrations of the shaft, also known as torsional vibrations. These vibrations are more important for heat engines, in which the movement of the cylinders is due to explosions.

These vibrations are also transmitted on the partition face and on the side of the accessories and can therefore lead to the wrong dynamics which is detrimental to engine efficiency, particularly at low speeds.

To compensate for these vibrations, it is known to use non-circular, but elongated, particularly elliptical transmission gears, i.e. the curve passing through the tip of the teeth is elongated or an ellipse. By rotating, these transmission wheels drive the belt around them, but this movement has a distance from the axis of rotation, which generates a periodic vibration whose signal overlaps with that of torsional vibrations. The elongation of these transmission wheels is provided so that this overlapping signal is in phase opposition with the torsional vibration signal. Thus, the amplitude of torsional vibrations is reduced.

However, these gears are difficult to achieve because they are not circular, the pitch of their teeth is not constant. They are also more expensive.

and 2018 00769

03/10/2018

The technical problem which the invention seeks to solve is therefore to improve the efficiency of the engine at a lower cost than that which J uses these non-circular transmission wheels.

To this end, a first object of the invention is a drive wheel intended to be connected to a drive shaft and to transmit the movement of this shaft to a moving part, the drive wheel being circular and having at the same time an angular distribution of uneven mass, this angular distribution of mass being arranged so that when the drive wheel is rotated on a shaft, it generates a periodic vibration on the shaft.

Angular distribution of an uneven mass means an angular distribution of an uneven mass around its axis of rotation, ie the angular distribution of the uneven mass means that the mass of the wheel around its axis of rotation is not constant.

Thus, this drive wheel is adapted to reduce the torsional vibrations of a drive shaft, whose torsional vibrations have one or more identical frequencies, so as to provide the drive wheel so that its vibration is in phase opposition. with torsional vibrations.

Thus, the total vibration, ie the resulting signal, transmitted by the drive wheel, for example to a drive belt, has a lower amplitude, thus improving engine efficiency.

>

Moreover, the transmission wheels according to the invention are cheaper and easier to make.

By definition, in this application, the parts and transmission elements of a device, such as the transmission wheel, are those that transmit the movement between the drive shaft of this device and an element of this mobile device in relation to the whole vehicle.

For example, in a vehicle, the transmission elements are those located between the wheels of the vehicle resting on the road and the drive shaft is the one that transmits the movement of this shaft to these wheels resting on the road. These transmission elements are also those that connect the drive shaft to other engine elements, such as the crankshaft motion transmission system to the camshaft.

The drive wheel according to the invention may optionally have one or more of the following characteristics:

and 2018 00769

03/10/2018 the wheel has at least one portion, hereinafter referred to as the private portion, having a mass per degree of angle less or greater than outside this angular sector; in particular, the angular distribution of the mass may be constant outside the particular portion or portions; making the wheel is easier;

the wheel has at least two particular portions, each arranged in a given angular sector, distinctly defined in relation to the axis of rotation of the drive wheel;

the particular portions are distributed in one or more pairs, so that for each pair, the corresponding particular portions are diametrically opposed to each other in relation to the axis of rotation of the drive wheel;

the wheel has two flanks separated by an edge, the angular distribution of the mass being uneven due to the holes, in particular the passage, formed in at least one flank of the transmission wheel; these holes can be easily formed on a conventional drive wheel so as to obtain a drive wheel according to the invention;

holes are formed by machining and / or drilling; In particular, the drive wheel according to the invention can be obtained by machining and / or drilling holes in a drive wheel with a constant angular mass distribution; this allows an economical realization, for example, starting from a gear or a classic pulley;

the wheel has two flanks separated by an edge, the angular distribution of the mass being uneven due to the protrusions formed on at least one flank of the transmission wheel;

the protrusions are attached glued or welded on the sides; In particular, the drive wheel according to the invention can be obtained by gluing and / or welding the protrusions on a drive wheel with a constant angular weight distribution; this allows an economical realization for example starting from a classic gear or pulley;

the drive wheel is a crankshaft end wheel and / or a camshaft;

the drive wheel is a pulley or a gear.

Another object of the invention is a vehicle engine comprising:

a drive shaft arranged so that, when the engine is running, the drive shaft rotates and in this case generates a specific periodic vibration, of 2018 00769

03/10/2018 drive wheel according to one of the preceding claims driven in rotation by the drive shaft, a moving part arranged with the drive wheel so that the drive wheel drives the moving part in motion, the angular distribution of the mass on the drive wheel provided that, when the engine is running, the periodic vibration generated by the drive wheel is in phase opposition to the specific periodic vibration of the drive shaft.

Thus, the engine according to the invention has a better efficiency, implementing a transmission wheel easier to achieve. In addition, the engine has a low cost.

The engine according to the invention may optionally have one or more of the following characteristics:

the drive wheel is mounted on the end of the drive shaft; the torsional vibrations resulting from the rotation of the drive shaft are thus reduced directly at the level of the drive shaft;

said moving part drives a mechanical element, in particular a shaft;

the engine is a heat engine; the invention is all the more useful in a heat engine, where the torsional vibrations are high;

the drive shaft is a crankshaft;

the moving part (7) is a belt or chain of a distribution system D or a belt or chain of an accessory drive system;

the mechanical element is a camshaft.

Another object of the invention is a vehicle comprising an engine according to the invention.

J in this application, the terms "vertical", "lateral" and "forward", as well as declensions in gender and number, shall be applied, unless otherwise indicated, in accordance with the guidance that they are intended to be fitted to the vehicle.

Other features and advantages of the invention will emerge from reading the detailed description of the following non-limiting examples, for the understanding of which we will refer to the accompanying drawings, in which:

figure 1 is a front perspective view of an engine according to the invention, without the representation of certain elements, in particular without the crankcase;

figure 2 is a side view of the engine distribution system of figure;

and 2018 00769

03/10/2018 figures 3 and 4 show state-of-the-art gears;

figure 5 is a side view of a transmission wheel according to a first embodiment of the invention;

figure 6 is a side view of a transmission wheel according to a second embodiment of the invention;

Figures 7 are a diagram illustrating the signals corresponding to the vibrations resulting from the drive shaft, the vibrations resulting from the wheel according to Figure 5 and the resulting vibrations propagated in the distribution system of Figure 2;

Figure 1 illustrates a vehicle engine 1, according to an embodiment of the invention, here a heat engine.

This figure 1 does not show all the elements, in particular the crankcase, the valves and the water pump.

In a conventional manner, this engine 1 comprises the pistons 2 moving in an alternating translational movement in the cylinders (not shown), due to the explosions in these cylinders. In their movement, the pistons 2 drive in rotation, through the connecting rods 3, a crankshaft 4 along the longitudinal axis Z of the latter.

This crankshaft 4 extends here on the one hand on a first end connected to a first transmission system, here the distribution system D and, on the other hand, a second end connected to a clutch 5.

Also in a classical manner, in this embodiment according to the invention, the distribution system D drives the camshaft 9 in rotation and has an arrangement that allows the synchronization of the inlet valves and the exhaust valves with the explosions and cyclic movements of the pistons 2. The better this timing, the better the efficiency of motor 1.

According to the embodiment of the invention and as illustrated in figures 1 and 2, the distribution system D comprises a drive wheel 10, formed here by a gear, and further a first drive wheel 10. The latter is mounted directly on the first end of the crankshaft 4. This forms the initial element for the transmission of the movement of the crankshaft 4 in the distribution system D.

The first drive wheel 10 then drives other moving parts of the distribution system D, these moving parts driving various mechanical elements of the engine. These moving parts are here:

and 2018 00769

03/10/2018

- the timing belt 7, which the first drive wheel 10 drives directly,

- moving parts driven indirectly by means of the timing belt 7, in particular the camshaft drive gears 8, the pulley 22 driving the water pump (not shown) and the gear 21 driving the injection pump (not shown) represented)

The distribution system D may also comprise at least one roller 23 arranged to maintain a tension on the distribution belt 7.

Moreover, the first end can, as here, be connected to an accessory drive system, also called FEAD (for Front-end Accessory Drives in English).

in figure 1, only the drive wheel 6 of the drive system is represented and is hereinafter referred to as the second drive wheel 6. The latter is here a pulley 6. The latter is mounted at the first end of the crankshaft 4, after the first drive wheel 10. The second drive wheel 6 drives a belt (which is not shown), which drives various moving parts of various mechanical members, such as the alternator (not shown). The second drive wheel 6 thus forms the initial element for transmitting the movement of the crankshaft 4 in the drive system of the accessories.

Moreover, the crankshaft 4 thus forms a drive shaft for the various moving parts and mechanical elements by means of these parts in the engine 1 and in the vehicle.

When the motor 1 is running, in particular due to the drive through the pistons 2, the crankshaft 4 does not rotate perfectly around its longitudinal axis Z, but will introduce oscillations in relation to it. These oscillations correspond to torsional vibrations, which are even stronger here because motor 1 is a heat engine.

These torsional vibrations correspond to a periodic vibration specific to this crankshaft. indeed, for a certain motor 1, the vibration specific to the drive shaft, here the crankshaft 4, is a periodic function, hereinafter the crankshaft signal S _v .

This crankshaft signal Sv is then transmitted by the first drive wheel 10 and the second drive wheel 6, respectively to the moving parts and the mechanical elements they drive, as indicated above. By 2018 00769

03/10/2018 therefore, it is likely to reduce the performance of these mechanical parts and the engine 1 itself.

in particular, the crankshaft signal Sv is transmitted to the timing belt 7, and then to all moving parts connected thereto, in particular the camshaft drive wheels 8, also called the camshaft pulleys 8. Thus, the vibrations of torsion will be transmitted to the camshafts and will affect their dynamics, with> J piston motion cycles 2.

To compensate for these torsional vibrations according to the invention, at least one circular drive wheel 10 with an unequal angular mass distribution is used. This angular distribution of the mass is arranged so that when the drive wheel 10 is rotated on a shaft, it generates a periodic vibration on the shaft. This periodic vibration specific to this wheel is therefore a periodic function, hereinafter a Sr. wheel signal.

This circular drive wheel or wheels according to the invention replace the elliptical drive wheels, such as those illustrated in Figures 3 and 4.

For example, according to a first embodiment, the first drive wheel 10 is made as shown schematically in Figure 5.

In this first example, the first drive wheel 10 has two flanks 15 separated by an edge 19. Figure 5 being a side view, relative to the orientation of the motor 1 in Figure 1, only one side 15 of the first drive wheel 10 is visible.

This first drive wheel 10 is called circular because the tips 16a of its teeth 16 pass through a circle.

The first drive wheel 10 has a central slot 13, so centered on the axis of rotation A1 of the first drive wheel 10. This central slot 13 allows the mounting of the first drive wheel 10 on the first end of the crankshaft 4.

The first drive wheel 10 has two particular portions 11, 12, each arranged in a given angular sector 17, 18 given separately. The two corresponding angular sectors 17, 18 are illustrated in Figure 5 by the dotted line segments starting from the axis of rotation A1 of the first drive wheel 10.

The first and second particular portions 11, 12 are formed here by through holes, which open on each flank 15.

Thus, the first and second particular portions 11, 12 have a lower mass per degree of angle than the portions of the first drive wheel 10 located outside their angular sectors 17, 18.

and 2018 00769

03/10/2018

Here, the two particular portions 11, 12 are diametrically opposed to each other with respect to the axis of rotation A1 of the first drive wheel 10.

This first example of a drive wheel 10 generates a wheel signal Sr on the shaft on which it is mounted.

Here, the first drive wheel 10 is oriented vertically, as can be seen in Figure 1, and has slight accelerations and decelerations during its rotation, due to the angular distribution of the uneven mass. In this example, those accelerations and decelerations generate the Sr. wheel signal.

This first transmission wheel 10 thus generates a wheel signal Sr, which is then superimposed on the crankshaft signal Sv- This overlap generates a global signal Sg- Figure 7 shows this overlap.

For simplicity, Figure 7 represents a single harmonic of the crankshaft signal Sv, the wheel signal Sr and the global signal Sg. The various periodic functions associated with the above-mentioned vibrations can indeed be decomposed in a classical harmonic manner. For each of these signals Sv, Sr, Sg, the harmonic represented in figure 7 is the harmonic having twice the fundamental frequency of each of these signals.

As can be seen in Figure 7, the particular portions 11, 12 are arranged in such a way that the crankshaft signal Sv and the wheel signal Sr are in phase opposition.

Thus, in this example and in a general way, the wheel signal Sv can have at least a frequency harmonic identical to a harmonic of the signal corresponding to torsional vibrations, here the Sv signal of the crankshaft. The drive wheel 10 is arranged on the drive shaft, here the crankshaft 4, so that these harmonics are in phase opposition.

As can be seen in Figure 7, the global signal Sg thus has a low amplitude.

As a result, the vibrations transmitted in the distribution system D are lower and the rotation of the camshafts 9 is more regular.

Thus, the first transmission wheel 10 makes it possible to obtain a signal in phase opposition, equivalent to an elliptical wheel whose circumference is schematically represented by the dotted ellipse in Figure 5, the distance between the axes of the ellipse (not shown) not being to scale.

and 2018 00769

03/10/2018

Therefore, the first drive wheel 10 is used as a replacement for the conventional elliptical gear 30, illustrated in Figure 3. In this figure 3, a disc portion 32 is illustrated to better see the lobes 33a, 33b of this elliptical gear. 30.

In the first drive wheel 10, the particular portions 11, 12, here with a reduced mass, generate the wheel signal S _R , while the lobes 33a and 33b are the ones that generate a wheel signal in the elliptical wheel 30.

By its shape, the elliptical wheel 30 therefore creates a periodic signal by changing the travel distance of the timing belt along its edge.

Instead, on the first drive wheel 10, the timing belt 7 moves at a constant distance, which prevents this timing belt 7 from being subjected to further voltage variations.

It should be noted that the camshaft drive gears 8, the water pump drive pulley 22 and the injection pump drive gear 21 also form transmission wheels. These drive wheels can also be arranged with an unequal angular distribution of mass so as to form a drive wheel according to the invention.

If only one of the transmission wheels of the distribution system D is

1 made according to the invention, it is better to be the first drive wheel 10 because it forms the initial element for transmitting the movement of the crankshaft 4.

It should be noted that the second drive wheel 6 can also be made with an angular distribution of the uneven mass according to the invention, so as to attenuate the vibrations transmitted to the accessory drive system.

Note that the holes forming the particular portions 11, 12 may be of different sizes.

The first drive wheel 10, according to the first embodiment, is particularly useful for generating a wheel signal S _R comprising a harmonic whose frequency corresponds to the second harmonic of the crankshaft signal Sv.

In general, a four-cylinder heat engine will generate a signal dominated by the second harmonic, while a six-cylinder engine will generate a signal dominated by the third harmonic. For a half ratio, the harmonics will be multiplied by two.

and 2018 00769

03/10/2018

Thus, for the engine according to the example shown in figure 1, which comprises four cylinders and a pulley mounted on the camshaft 9, a first transmission wheel 110 can also be used according to a second embodiment illustrated in figure 6. Indeed, according to this second example, the camshaft pulley 8 generates a signal including a harmonic whose frequency corresponds to the fourth harmonic of the crankshaft signal S _v (i.e. the second harmonic multiplied by 2). The efficiency of engine 1 is thus improved.

In this second example, the first drive wheel 110 is also circular, the tips 116a of the teeth 116 passing through a circle. The first drive wheel 110 also has two flanks 115 separated by an edge 119.

instead, in this second example, four particular portions are provided. The first drive wheel 110 actually has a first pair of particular portions 111, 112 and a second pair of particular portions 113, 114, each arranged in a given, distinct angular sector (not shown).

The particular portions 111, 112 of the first pair are formed here of through holes, which thus open on each side 115 of the first transmission wheel 110.

Thus, the first and second particular portions 111, 112 of the first pair have a lower mass per degree of angle than the portions of the first drive wheel 110 located outside their angular sectors.

The particular portions 113, 114 of the second pair are formed here of projections arranged on a flank 115 of the first transmission wheel 110.

Thus, the first and second particular portions 113, 114 of the second pair have a mass per angle greater than the portions of the first drive wheel 110 located outside their angular sectors.

Here, the two particular portions 111, 112 and 113, 114 of each pair are diametrically opposed to each other with respect to the axis of rotation A2 of the first drive wheel 110. In other words, the holes shown are diametrically opposed and the protrusions are diametrically opposed. opposite.

In the second example, this first drive wheel 110 is intended to be mounted on the crankshaft 4 to affect the fourth harmonic or on the camshaft 9 (for a four-cylinder engine and the ratio of 0.5 between the first drive wheel and the camshaft pulley 8), so as to generate a wheel signal on the shaft, the wheel signal being in phase opposition with that of the crankshaft 4.

and 2018 00769

03/10/2018

This makes it possible to substantially reduce the fourth harmonic and therefore most of the torsional vibrations transmitted to the D distribution system.

Thus, the first drive wheel 110 makes it possible to obtain a signal equivalent to that generated by a conventional wheel with four lobes inscribed in two ellipses and whose contours are represented schematically by the dotted ellipses in Figure 6, the distance between the axes of the ellipses (not shown) not being scale.

The first drive wheel 10 is thus used as a replacement for a conventional four-lobe sprocket 35, illustrated in Figure 4. In this figure 4 a disc portion 37 is illustrated to better visualize the lobes 38a to 38d.

The first drive wheels 10, 110 described may consist of conventional drive wheels, in particular with constant angular mass distribution.

For example, according to an example of a method of making the first transmission wheels, the following steps are performed:

determining a periodic vibration specific to the drive shaft, here the crankshaft 4, when the engine 1 rotates, taking a drive wheel, here a sprocket with solid flanks, with a constant angular distribution of mass, achieving an unequal angular distribution of mass by making a hole 11, 111 on at least one of the flanks; Alternatively, for the second example, a protrusion 113 could be achieved first by adding material, then performing a three to four rotation of the drive wheel 10, 110, then observing the signal corresponding to the vibration specific to this wheel 10 , 110.

Next, for the first example of a first drive wheel 10, the process continues with the following additional steps:

return to the stage of achieving an angular distribution of mass distribution, forming the second hole 12 so as to approach a wheel signal S _R which has at least one harmonic at the same frequency as at least one crankshaft signal harmonic Sv , here the second harmonic, then, the return as many times as necessary at the stage of achieving an inequality of angular distribution of mass, modifying at least one hole 11, 12 until the wheel signal S _R has at least one harmony at the same frequency with at least one harmonic of the Sv signal of the crankshaft, here the second harmonic.

and 2018 00769

03/10/2018 in the second example, the basic steps are completed to obtain a signal corresponding to the fourth harmonic, so we will return at least three times to the steps of achieving an angular inequality of mass distribution, respectively, by adding the second hole 112, then the first protrusion 113, then the second protrusion 114.

In the first example, the procedure can be simplified by studying only the signal corresponding to the second harmonic of the crankshaft signal Sv.

In the second example, the method can be simplified by studying only the signal corresponding to the fourth harmonic of the crankshaft signal Sv.

Note that in the fourth example, the first drive wheel 110 may generate the fourth harmonic which may be predominant.

This process facilitates obtaining, in particular by machining, drilling, welding and / or gluing, a drive wheel according to the invention from a conventional circular drive wheel.

To achieve the three to four rotations of the drive wheel 10, 110, the wheel can be mounted on a horizontal axis of a measuring bench. The rotational speed is then recorded at a very low speed. The corresponding signal will correspond to a sinusoid associated with different accelerations and decelerations due to mass differences. The holes and protrusions can be adjusted so that these variations correspond to the desired signal which must be in phase opposition to the crankshaft signal.

We can also complete the process with a so-called dynamic observation in which the wheel rotates at a high rotational speed, in which the corresponding signal is observed. Then, the wheel signal is adjusted in this dynamic operation to the crankshaft signal, advantageously changing the particular portions 11, 12 or 111 to 114.

In this dynamic observation, it is possible, in particular, to rotate the wheel at the rotational speed corresponding to the engine speed for which it is desired to improve the efficiency, in particular at low speed, such as the urban traffic regime.

Although in the illustrated examples the invention is applied to a crankshaft of a heat engine, it can be applied to any drive shaft, including the non-heat engine, for which torsional vibrations are likely to be transmitted to other elements of the engine or device containing this engine.

Claims (13)

1. The drive wheel (10; 110) for movement to be connected to a drive shaft (4) and to transmit the movement of this shaft to a moving part (7), the drive wheel being circular and having an angular distribution of mass uneven, this angular mass distribution being arranged so that when the drive wheel is rotated on a shaft, it generates a periodic vibration on this shaft. A drive wheel (10; 110) according to claim 1, wherein the wheel has at least one portion, hereinafter referred to as a particular portion (11, 12; 111, 112, 113, 114), which has a mass per degree of angle smaller or larger than outside this angular sector. A drive wheel (10; 110) according to claim 2, wherein the particular portions (11, 12; 111, 112, 113, 114) are distributed in one or more pairs, such that for each pair, the particular portions correspond to be diametrically opposed to each other in relation to the axis of rotation (A1; A2) of the drive wheel. Drive wheel (10; 110) according to one of the preceding claims, having two flanks (15; 115), separated by an edge (19; 119), in which the angular distribution of the mass is uneven due to the holes (11, 12; 111, 112) formed in at least one side of the drive wheel. The drive wheel (10; 110) of claim 4, wherein the holes (11, 12; 111, 112) are formed by machining and / or drilling. Transmission wheel (110) according to one of the preceding claims, having two flanks (115) separated by an edge (119), in which the angular distribution of the mass is uneven due to the protrusions (113, 114) formed on at least one side of the transmission wheels. and 2018 00769 03/10/2018 A transmission device (110) according to claim 6, wherein the protrusions (113, 114) are attached, glued or welded parts on said one or more flanks. 8. Vehicle engine (1), comprising: - a drive shaft (4) arranged so that, when the engine is running, the drive shaft is rotated and in this case generates a specific periodic vibration, - a drive wheel (10; 110) according to one of the preceding claims, driven in rotation by the drive shaft, - a moving part (7, 8, 21, 22) arranged together with the drive wheel so that the drive wheel drives the moving part, the angular distribution of the mass on the drive wheel being arranged so that, when the engine is in function, the periodic vibration generated by the drive wheel is in phase opposition with the specific periodic vibration of the drive shaft. The engine (1) of claim 8, wherein the drive wheel (10; 110) is mounted on the end of the drive shaft (4). An engine (1) according to claim 8 or 9, wherein the engine is a heat engine. The motor (1) of claim 10, wherein the drive shaft (4) is a crankshaft. The motor (1) of claim 10 or 11, wherein the moving part (7) is a belt or chain of a timing system (D) or a belt or chain of an accessory drive system. A motor vehicle comprising an engine (1) according to one of claims 8 to 12.