WO2016174322A1

WO2016174322A1 - Eccentric component for a system for varying the compression ratio of a combustion engine

Info

Publication number: WO2016174322A1
Application number: PCT/FR2016/050724
Authority: WO
Inventors: Matthieu POGAM; Julien Berger; Lambertus Hendrick DE GOOIJER; Sander Wagenaar; Willem-Constant Wagenvoort
Original assignee: Peugeot Citroen Automobiles Sa; Gomecsys B.V.
Priority date: 2015-04-28
Filing date: 2016-03-31
Publication date: 2016-11-03
Also published as: FR3035681A1; FR3035681B1

Abstract

The invention relates mainly to an eccentric component (18) for a system for varying the compression ratio of an internal combustion engine, said eccentric component comprising: - a body (30) with no teeth having an eccentric face (31), and - two toothed rings (32) positioned one on each side of said eccentric face (31), characterized in that each toothed ring (32) is made up of two parts (321, 322) that are joined to one another.

Description

ECCENTRIC PIECE FOR SYSTEM OF VARIATION OF THE RATE OF

COMPRESSION OF A THERMAL ENGINE

The present invention relates to an eccentric piece for a variation system of the compression ratio of a heat engine.

The document EP14163870.0 teaches the realization of a compression ratio variation system depending on the operating conditions of the engine. This system of variation of the compression ratio comprises a set of eccentric parts mounted on the crankshaft crank pins so as to cooperate each with a connecting rod end.

The eccentric parts are split into two parts to allow their assembly on a one-piece crankshaft. As shown in Figure 1, each eccentric part 1 is assembled on the crankshaft by fitting four connecting pieces 2 in the form of "dog bones" intended to cooperate with housings 3 'maneuvered in half-shells 3 which in advance are centered with the aid of pins 4. In such a connection, the support planes of the male part (corresponding to the end 2 'of the part 2) and the female parts (corresponding to the housing 3' of a half-shell 3) have respective angles of lateral inclinations such that the more the male part is deep in the female part, the more there is binding force between the half-shells 2. problems of mechanical resistance.

Furthermore, as shown in FIG. 3, a control system 5 comprises an actuating shaft 6 and a cascade of sprockets constituted by an actuating pinion 7 mounted on the actuating shaft 6. and an intermediate gear 8 said satellite meshing on the one hand with the drive pinion 7 and on the other hand with the eccentric part 1. Such a configuration imposes a ratio of -1/2 between the crankshaft and the eccentric part 1 relative to the frame. This requires having two times less teeth on the actuating pinion 7 than the eccentric part 1 and reversing the direction of rotation by means of the planet pinion 8.

In operation and when the actuating shaft 6 is fixed in rotation relative to the frame, the system has a fixed compression ratio configuration. In transient rate and via the gear ratio of -1/2, the angular position of the eccentric piece is controlled by the angular position of the actuating shaft 6 to thus pass to a new compression rate point. For this purpose, through the journals of the crankshaft, shafts and so-called transfer gears transmit the kinematics of the eccentric piece located on the side of the actuating shaft step by step to all the other eccentric parts of the crankshaft.

Such architecture however has the disadvantage of generating a local fragility of the crankshaft. Indeed, for the cutting of the teeth on the eccentric parts, it is difficult to get out the cutting and / or grinding tools (hob, rack, grinding wheel) for a tooth root diameter below the area of rod guide referenced ZG in Figure 2. In addition, the crankpin diameter 9 of the crankshaft 10 and the eccentricity impose a minimum diameter of the teeth of the teeth of the eccentric parts 1.

Furthermore, on each gear station, the transmissible torque must be greater than the torque to be transmitted, which implies a specific geometry of the teeth and in particular a minimum tooth head diameter for a known root diameter. Thus, the known configuration imposes, having to shift the meshing plane of the actuating gear 7 with the planet pinion 8 with respect to the gear plane of the eccentric part 1 with the planet pinion 8, as shown in FIG. FIG. 3. This makes it possible to avoid interference between the teeth of the actuating gear 7 and the teeth of the eccentric part 1.

This shift of the gear planes requires digging the crankshaft in an area 10 'to integrate the drive pinion 7 and a portion of the pinion 8, which locally weakens the mechanical strength of the crankshaft.

The invention aims to effectively remedy these drawbacks by providing an eccentric piece for a variation of the compression ratio of an internal combustion engine system comprising:

a body devoid of toothing having an eccentric face, and

- Two ring gear positioned on either side of said eccentric face, characterized in that each ring gear consists of two parts assembled together.

The use of such an eccentric piece makes it possible, at iso-tooth height with respect to the known eccentric piece, to reduce the diameter of the toe of the eccentric teeth, especially below the guide diameter of connecting rod, which is not possible with the aforementioned configuration for the reasons mentioned above for output of cutting tools and / or grinding of teeth. By readjusting the number of teeth of the pinions while ensuring the same kinematics, the meshes between the drive pinion and the eccentric part and between the eccentric piece and the pinion satellite are conceivable on one and the same plane. There is no longer need to come dig the crankshaft to integrate the drive pinion and part of the pinion satellite. The crankshaft is no longer locally weakened.

[001 1] In one embodiment, said body is made of two parts assembled together.

In one embodiment, said piece has weld traces between the parts of the toothed crowns and said body.

In one embodiment, the weld traces are located at a circumference of axial end edges of said body.

In one embodiment, said weld traces are constituted by a continuous weld line.

In one embodiment, said weld traces are constituted by a succession of solder points.

In one embodiment, said traces are traces of laser welding.

According to one embodiment, a junction zone between the parts of said body and the junction areas between the parts of the toothed crowns are in two different planes inclined relative to each other.

In one embodiment, said planes are perpendicular to one another.

The invention also relates to an internal combustion engine of a motor vehicle comprising:

- a crankshaft, and

a system for varying a compression ratio of said motor comprising at least one eccentric part as previously defined mounted on a crank pin of said crankshaft. The invention will be better understood on reading the description which follows and the examination of the figures that accompany it. These figures are given for illustrative but not limiting of the invention.

Figure 1, already described, is an exploded perspective view of an eccentric part according to the state of the art;

Figure 2, already described, is a side view of the eccentric part of Figure 1 mounted on a crank pin;

Figure 3, already described, is a perspective view illustrating the shift between the meshing planes of the drive pinion with the pinion and the eccentric piece with the pinion satellite in the context of a use of the eccentric part of Figure 1;

Figure 4 is a perspective view illustrating the integration of the compression ratio variation system of a heat engine according to the present invention along the entire length of the crankshaft;

Figure 5 is a perspective view of the compression rate variation system of a heat engine according to the present invention without the crankshaft;

Figure 6 is an exploded perspective view of an eccentric part according to the present invention;

Figure 7 is a perspective view illustrating the meshing of the drive pinion with the pinion and the eccentric piece with the pinion satellite in the same plane for use of the eccentric part of Figure 6 ;

[0028] Figure 8 shows an exploded perspective view of an eccentric piece mounted on a crankpin of the crankshaft via internal bearings;

Figure 9 shows a longitudinal sectional view of a crankshaft on which is installed an eccentric part made according to an alternative embodiment of the invention.

In Figures 4 to 9, the identical elements, similar, or the like, retain the same reference from one figure to another. FIG. 4 shows a perspective view of a system 1 1 for varying the compression ratio making it possible to operate an internal combustion engine at a high compression ratio under low load conditions in order to improve its efficiency. . Under high load operating conditions, the compression ratio can be decreased to avoid jolts.

More specifically, the crankshaft 12 of the X-axis motor is intended to be rotatably mounted on a motor housing by means of bearings. The crankshaft 12 comprises a plurality of crank pins 13, and journals 14, separated by flanges 15 extending substantially perpendicularly with respect to the axis X.

The crankshaft 12 further has a front end intended to be rotatably connected with a pulley. An flywheel (not shown) is rotatably connected to the rear end of the crankshaft 12.

Eccentric parts 18 are rotatably mounted on the crank pins 13. As can be seen more clearly in FIG. 5, each eccentric part 18 comprises a body 30 without teeth with an eccentric external face 31 intended to cooperate with a large diameter. end of a rod (not shown), which has its small end rotatably connected with a piston of the engine. The eccentric part 18 also comprises two toothed rings 32 positioned on either side of the eccentric external face 31.

A control system 20 of the angular position of the eccentric parts 18 comprises an actuating shaft 21 and a cascade of sprockets constituted by an actuating pinion 22 mounted on the actuating shaft 21, and an intermediate gear 23, said satellite, to reverse the direction of rotation, meshing on the one hand with the actuating pinion 22 and on the other hand with a ring gear 32 of the eccentric piece 18.

In operation and when the actuating shaft 21 is fixed in rotation relative to the frame, the system has a fixed compression ratio configuration. In transient rate, the angular position of the eccentric part 18 located on the side of the pulley is controlled by the angular position of the actuating shaft 21 and thus pass to a new compression ratio point. For this purpose, the actuating shaft 21 may be actuated for example by means of a wheel and worm gear, or any other means of displacement adapted to the application. In addition, through the journals 14 of the crankshaft 12, 26 shafts and so-called transfer gears 27 transmit the same kinematics of the eccentric part 18 located on the side of the actuating shaft 21 step by step on all the other eccentric parts 18 of the crankshaft 12. To this end, the pinions 27 mounted on the shafts 26 meshing with the ring gear 32 of the other eccentric parts 18.

More specifically, as can be seen in Figure 6, the body 30 of the part 18 has an inner face 33. Internal bearings 401, 402 clearly visible in Figure 8 are intended to be mounted on this inner face 33 and to form a hydrodynamic bearing with the outer periphery of the crankpin 13. The inner face 33 and those of the inner bearings 401, 402 have an axis substantially coinciding with the axis of the crankpin 13, while the outer face 31 is eccentric with respect to this inner face 33. The diameter of the inner face 33 corresponds to the outside diameter of the crankpin 13, to the thickness of the inner bearings 401, 402 and the nominal clearance of the hydrodynamic bearing. The eccentric face 31 is formed on a shoulder 34 against which the two toothed rings 32 are axially supported. For this purpose, the body 30 comprises two sections 35 located on either side of the shoulder 34 whose inner diameter corresponds to the face 33 and whose outer diameter corresponds to the inner diameter of the toothed crowns 32. The width of the sections 35 is substantially equal to the width of the toothed crowns 32.

The body 30 is in this case formed of two parts 301, 302 assembled together. Each portion 301, 302 is in the form of a half-ring comprising a corresponding portion of the shoulder 34 and two sections 35. These half-rings 301, 302 are intended to come each to press on half of the circumference of the bearing hydrodynamic formed by the inner pads 401, 402 and a crankpin 13.

In addition, each ring gear 32 is formed of two parts 321, 322 assembled together. Each portion 321, 322 is constituted in this case by a half-crown. The half-rings 321, 322 are intended to come flat each on half of the circumference of a corresponding section 35.

The assembly of the half-rings 321, 322 and half-bodies 301, 302 is performed on the crankshaft 12 by welding, preferably of the laser type, at the boundaries between these different parts. In this case, the welds 38 are made at a circumference of the axial end edges of the body 30. The welds 38 may be made in a continuous line or in a succession of weld points. The finished eccentric piece 18 will thus have corresponding weld marks. Alternatively, the welding technique is a technique other than the laser adapted to the present application.

Furthermore, a junction zone between the half-bodies 301, 302 and the junction zones between the half-rings 321, 322 are located in two different planes P1, P2 inclined with respect to each other. . The planes P1, P2 are preferably perpendicular to each other, but could alternatively be inclined at a different angle with respect to each other.

In the embodiment of FIG. 9, the internal faces of the half-rings 321, 322 and the corresponding external faces of the half-bodies 301, 302 (at the level of the sections 35) are inclined in the junction zones 44 with respect to the axis of the crank pin for assembly by laser welding (s). The inclination between these faces is such that the thickness of the section of the sections 35 increases as one moves from the axial end of a section 35 located on the side of the center of the part 18 towards the free axial end of the section 35 corresponding to the end of the part 18. This improves the axial retention of the half-rings in the assembly during operation of the engine.

In addition, the laser welds may have an angle of inclination with respect to the axis of the pin 13. In addition to the space saving obtained from a point of view of the welding process, such an inclination angle allows to increase the useful welding surfaces for the same width.

Alternatively, the body 30 is monobloc, that is to say that it is made in one part, while the crankshaft 12 is made in several parts to allow the establishment of the body 30 with the In the alternative, only the half-rings 321, 322 are mounted reported on the assembly. Alternatively, the parts 321 and 322 are monoblock and are reported (by welding or shrinking) on the assembly.

The use of eccentric parts 18 according to the aforementioned configuration allows, at iso-height of tooth relative to the known eccentric piece (see Figure 1), to reduce the diameter of the tooth root of the eccentric teeth, in particular below the rod guide diameter, which is not possible with the aforementioned configuration for reasons of output of cutting tools and / or grinding of teeth. By readjusting the number of teeth of the gears while guaranteeing the same kinematics, the meshes between the actuating gear 22 and the planet pinion 23 and between the eccentric part 18 and the planet pinion 23 are feasible on one and the same plane P3, as illustrated by FIG. 7. There is then no longer need to come dig the crankshaft 12 to integrate the drive gear 22 and a portion of the planet pinion 23. The crankshaft 12 is no longer locally weakened.

Claims

Eccentric part (18) for a system (1 1) for varying the compression ratio of an internal combustion engine comprising:

- a body (30) without teeth with an eccentric face (31), and

two toothed rings (32) positioned on either side of said eccentric face (31),

characterized in that each ring gear (32) consists of two parts (321, 322) assembled together.

2. Eccentric part according to claim 1, characterized in that said body (30) consists of two parts (301, 302) assembled together.

3. eccentric part according to claim 1 or 2, characterized in that said eccentric piece (18) has weld traces (38) between the portions of said ring gear (32) and said body (30).

4. Eccentric part according to claim 3, characterized in that said traces of welds (38) are located at a circumference of axial end edges of said body (30).

5. Eccentric part according to claim 3 or 4, characterized in that said solder traces (38) consist of a continuous weld line.

6. eccentric piece according to claim 3 or 4, characterized in that said solder traces (38) consist of a succession of weld points.

7. Eccentric part according to any one of claims 3 to 6, characterized in that said solder traces (38) are traces of laser welding.

8. Eccentric part according to claim 2, and if appropriate any one of claims 3 to 7, characterized in that a junction zone between the parts of said body (30) and the junction areas between the parts of the crowns teeth are located in two different planes (P1, P2) inclined relative to each other.

9. eccentric piece according to claim 8, characterized in that said planes (P1, P2) are perpendicular to each other.

10. Internal combustion engine of a motor vehicle comprising:

a crankshaft (12), and

- A system (1 1) for varying a compression ratio of said motor having at least one eccentric piece as defined in any one of the preceding claims mounted on a crankpin (13) of said crankshaft (12).