EP0938627B1 - Internal combustion engine - Google Patents

Abstract

PCT No. PCT/FR97/02035 Sec. 371 Date Jul. 14, 1998 Sec. 102(e) Date Jul. 14, 1998 PCT Filed Nov. 13, 1997 PCT Pub. No. WO98/21458 PCT Pub. Date May 22, 1998An internal combustion engine comprising the power take-off shaft and at least first and second crankshafts connected to the power take-off shaft by first and second linkages, respectively. The first and second linkages are each severable when their respective crankshafts are immobilized (e.g., by failure), such that the engine can continue to operated using the power from the operating crankshaft. The linkages break under a load less than or equal to a load necessary to immobilize the respective crankshafts.

Description

The present invention relates to internal combustion engines comprising at least a first crankshaft linked to an engine output shaft by means of a first rotation link, a second crankshaft linked to the engine output shaft by means of a second rotating link, and more particularly relates to the motors intended to equip motorized ultralight (U.L.M.), gyroplanes, amateur light aircraft, hovercraft, hydrofoils, drones, or the like.

A primary problem in this type of application in case of engine malfunction is nevertheless to ensure the safety of pilots and potential passengers, and to allow them to reach a stopping point with maximum security. Another problem is to avoid destruction of equipment due to incidents or accidents caused directly or indirectly by engine malfunctions. Consequently, a motorization for such applications must be very reliable and robust, and yet remain light, powerful, and convenient.

The document EP 0316 286 describes an engine unit for an ultra-light aircraft, comprising an engine block carrying at least one pair of autonomous driving units, with drive shafts independently connected to an output shaft common to the means of unidirectional transmission units, each comprising a free wheel, arranged to couple the output shaft and the drive shafts in rotation only when the respective drive units are in condition of operation.

Such a power unit, due to the unidirectional transmissions, presents the major drawback of not being able to guarantee a predetermined angular setting and necessary drive units together with respect to the output shaft, for example 180 ° for two units, 120 ° for three, etc., to ensure a balanced distribution of forces on the output shaft, and therefore correct operation of the engine group. In addition, a such engine group does not allow to use the output shaft to transmit a rotational movement to the driving units, for example thanks to the inertia of the shaft output and propeller mounted on it, or to start the engine group at from the output shaft. In addition, such a power unit has the disadvantage of require as many freewheel devices as there are drive units, such a device being particularly particularly bulky; in the case of the referenced document, the freewheels are placed on the output shaft one behind the other, resulting in takes up axial space in the motor unit and a very propeller shaft overhang important.

The object of the present invention is to propose a solution to the above problems and to bring other benefits. More specifically, it consists of an internal combustion engine comprising at least a first crankshaft linked to an output shaft of said engine at by means of a first rotation link, a second crankshaft linked to said output shaft of the engine by means of a second rotating link, characterized in that said first rotation link is reversible and includes a first drive wheel linked in a way complete in rotation to said first crankshaft via a first link by obstacle capable of transmitting an engine force from said first crankshaft to said shaft exit and capable of breaking, during a malfunction resulting in immobilization of said first crankshaft, under an effort less than or equal to the effort necessary for immobilization of said first crankshaft, and in that said second rotation link is reversible and includes a second drive wheel linked in complete rotation to said second crankshaft via a second obstacle connection capable of transmitting an engine effort from said second crankshaft to said output shaft and capable break, during a malfunction resulting in immobilization of said second crankshaft, under an effort less than or equal to the effort required to immobilize said second crankshaft.

The engine according to the invention can operate despite the immobilization of a crankshaft at least, by means of a controlled rupture of the link connecting the output shaft to the crankshaft immobilized or intended to immobilize following a malfunction, for example example a piston tightening. In an engine according to the invention intended to equip a U.L.M. or the like for example, the output shaft which is integral with the propeller, may continue to turn despite the immobilization of a crankshaft, under the effect of the engine torque provided by the or non-immobilized engine crankshafts. Thus, the U.L.M. or the like can win a safe landing point, instead of being subject to the hazards of gliding in the event of the U.L.M. or fall in the case of an autogyro for example. It should be noted that the engine according to the invention may advantageously comprise more than two crankshafts.

According to an advantageous characteristic, the engine according to the invention comprises at least a third crankshaft, a third rotation link, a third drive wheel, a third obstacle connection.

This characteristic concerns an engine with three crankshafts each linked to the output shaft via an obstacle bond capable of breaking. In the case of an asset of any of the crankshafts, the engine continues to run on two other crankshafts, the immobilized crankshaft being disengaged from the output shaft by the rupture of the link by obstacle concerned.

The invention will be better understood and other characteristics and advantages will appear. the following reading of an exemplary embodiment of a motor according to the invention, accompanied attached drawings, example given by way of illustration and without any interpretation restrictive of the invention cannot be drawn from it.

Figure 1 shows an exploded partial front view of the exemplary embodiment of an engine according to the invention.

Figure 2 shows a partial sectional view along line I-I of Figure 1.

Figure 3 shows an enlarged detail of Figure 2, more particularly relating to the connection by obstacle.

Figures 4 and 5 show the same isolated element of Figure 2, in perspective for the figure 4 and in back view for figure 5.

Figures 6 and 7 show the same isolated element of Figure 1, in perspective for the Figure 6 and in side view for Figure 5.

The engine 1 shown in Figure 1 is an internal combustion engine with three cylinders 2, 3, 4 placed in a star (not shown), two times, particularly suitable for equip the machines mentioned above. Each cylinder 2, 3, 4 corresponds a crankshaft 5, 6, 7 respectively. The motor 1 shown in Figures 1 and 2 comprises a first 5 crankshaft linked to an output shaft 8 of the engine by means of a first rotation link, a second 6 crankshaft linked to the output shaft 8 of the engine by means of a second connection in rotation, a third 7 crankshaft linked to the output shaft 8 of the engine by means a third rotating link. The first 5, second 6, and third 7 crankshafts are guided in rotation in a casing 9 according to any known means, for example by means of bearings 10 as shown in figure 2. It should be noted that figure 2 corresponds to a section along the first cylinder 2, along the line I-I in FIG. 1, but may correspond indifferently to the similar cut according to any one of the other two cylinders 3 and 4. The output shaft 8 is the drive shaft from which the engine power is recovered, and carries a propeller (not shown) in the example.

The first rotating link is reversible and includes a first 11 drive wheel linked in complete rotation to the first 5 crankshaft via a first obstacle connection capable of transmitting an engine force from the first 5 crankshaft towards the output shaft 8 and capable of breaking, during a resulting malfunction immobilization of the first 5 crankshaft, under an effort less than or equal to the effort necessary to immobilize the first 5 crankshaft. The second rotating link is reversible and includes a second drive wheel linked in complete rotation to the second 6 crankshaft via a second suitable obstacle connection to transmit an engine force from the second 6 crankshaft to the output shaft 8 and capable to break, during a malfunction resulting in immobilization of the second 6 crankshaft, under an effort less than or equal to the effort required to immobilize the second 6 crankshaft. The third rotating link is reversible and includes a third 26 drive wheel linked in full rotation to the third 7 crankshaft by through a third obstacle connection capable of transmitting a motor force from the third crankshaft to the output shaft 8 and capable of breaking, in the event of a malfunction causing immobilization of the third 7 crankshaft, under a lower effort or equal to the effort required to immobilize the third 7 crankshaft.

The first, second, and third rotational links are advantageously links by gear, as shown in Figures 1 to 3.

Advantageously, the first 11, second 25, and third 26 drive wheels, are engaged on a fourth 12 driven wheel linked in complete rotation to the output shaft 8, by any known means, for example by a key 30, as shown in Figures 1 and 2.

It will be noted that the motor shown in Figures 1 and 2 advantageously allows a mounting in which the first 11, second 25, third 26 drive wheels, and fourth 12 driven wheel are substantially or exactly located in the same plane, the first 11, second 25, and third 26 integral drive wheels respectively first 5, second 6, and third 7 crankshafts being engaged on the circumference of the fourth 12 wheel driven at an angular offset, for example equal to 120 ° in the case of the three-cylinder star engine, as shown in Figure 1. Thus, the engine according to the invention has a significant longitudinal functional compactness, simplicity and a rationality of the transmission of the movement, allowing a reduction of the clutter and engine weight, and increased reliability.

It should be noted that in the description part which follows, it will only be described the first obstacle connection, the second and third obstacle connections being advantageously similar at the first obstacle connection. In addition, each of the three obstacle links has the function of transmitting the engine force from the crankshaft concerned to the output shaft while by allowing the rotational connection between this crankshaft and the output shaft to be broken case of immobilization of this crankshaft as a result for example of a tightening of the actuating piston the crankshaft concerned. Several pistons can actuate the same crankshaft, the optionally. Thus, the tightening of a piston for example, authorizes the operation of the engine. on the two remaining cylinders, thanks to the disengagement of the immobilized crankshaft, which gives to the motor according to the invention great operational safety.

The first obstacle connection comprises at least one shear pin 13. The pin 13 can be replaced by a shear key (not shown) or the like, and its dimensions and material will be advantageously chosen, when the dowel (s) constitute the only obstacle of the obstacle connection, so that the section or sections shear, two in number in the example of the figures, resist the transmission of the maximum engine force of the crankshaft concerned in normal engine operation, and will be also chosen so that the plug (s) shear under a lower force or equal to the effort required to immobilize the crankshaft concerned when the engine is Operating.

As shown in FIG. 3, the first obstacle connection comprises a first shear pin 13, or the like, and advantageously further comprises a first drive stop 14 capable of transmitting the engine force from the first 5 crankshaft to the output shaft. The first stop 14 has the essential purpose of avoiding that the driving force is transmitted by the shear pin, and that the shear pin is used only when the crankshaft offers resistance to the exit. Thus, the dimensions and the material of the dowel will be chosen so that it can shear under an effort less than or equal to the effort required to immobilize the first 5 crankshaft when the engine is running, the ankle in front obviously resist the maximum resistant force which the crankshaft can oppose to the shaft of output in normal engine operation. Note that in Figure 3, the elements of casing have not been shown, the elements shown not being in section.

The first drive stop 14 advantageously comprises at least one asymmetrical tooth 15 held in engagement in a hollow housing 16 of complementary shape, at means of pin 13, key, or the like, for shearing, as shown in the figure 3.

The asymmetric tooth 15 preferably comprises a first face 17 capable of transmitting the motor force and a second face 18 opposite the first face 17, making it possible to avoid engagement of the asymmetric tooth 15 in the recess 16 in the event of rupture of the pin 13, key, or the like, for shearing. The first face 17 is preferably included in a plane passing through the axis of rotation of the crankshaft concerned so that the force transmitted is perpendicular to face 17, and the second face 18 of the asymmetric tooth 15 advantageously has an appropriate inclination, as shown in the figure 3, so that the tooth 15 is driven out of the housing 16 when the ankle breaks 13, and cannot be reintroduced.

It should be noted that the presence of the drive stop introduced by the second face 18 inclined tooth 15, an axial component and additional friction for the ankle breakage 13, which must be taken into account in determining the material and dimensions of the anchor 13 according to any known means, calculation or experimental method for example.

The first drive stop 14 advantageously comprises, as shown in FIG. 3, a plurality of teeth 15 forming a first crown extending in a first plane perpendicular to a longitudinal axis of the first 5 crankshaft. Crown teeth are preferably identical to that described above. The plurality of teeth allow evenly distribute the pressure circumferentially on the first 5 crankshaft and the first 11 drive wheel, and reduce the dimensions of this accordingly drive stop 14. The teeth of the crown can be produced on the wheel 11, the corresponding recessed housings then being produced on the crankshaft 5, or vice versa.

Figures 4 and 5 show the wheel 11 alone, isolated from the connection, on the scale of the figure 3, and highlights the crown of asymmetrical teeth 15, comprising 12 teeth.

Figures 6 and 7 show the crankshaft 5 alone, on the scale of Figure 2, and highlights the crown of housings 16 complementary to the asymmetrical teeth 15, comprising 12 homes. Note also in these figures the presence of a diametral hole in the cylindrical part 20 to accommodate the pin 13, and a groove to accommodate an elastic ring 24 as will be explained below.

As shown in Figures 3 to 5, the first drive wheel 11 has a bore 19 allowing centering thereof on a cylindrical part 20 of circular section at the end of the first crankshaft 5 so that the wheel 11 can rotate around the crankshaft 5, when the ankle 13 has broken. The above concerns indifferently the first, second, or third link in rotation.

The motor 1 will have any suitable known means intended to reduce friction a drive wheel on the associated crankshaft in case of breakage of the connection by obstacle, for example mounting the wheel on the crankshaft via one or more bearings (not shown) capable of allowing additional movement possible in translation of the drive wheel on the crankshaft, or via a ring or bearing 22 (not shown). The bearing material can be chosen so to resist the pressure due to the transmitted forces and for its ability to reduce friction, for example bronze.

The end of the cylindrical part of the crankshaft will be fitted with any means necessary to retaining the drive wheel on the crankshaft in the event of breakage of the connection by obstacle, for example a ring or elastic ring 24 as shown in FIG. 3.

All the drive wheels and the driven wheel 12 will advantageously be enclosed in a sealed and lubricated casing 21, as shown in FIG. 2, in order to ensure lubrication of the rotational connections between the crankshafts and the output shaft, when these connections require such lubrication, such as gear connections metallic. This lubrication can advantageously be carried out by bubbling or the like. The lubrication of rotating links can advantageously be used in order to lubricate if necessary rotation of the drive wheel on the crankshaft in case of breakage of the link by obstacle. It should be noted that the casing 21 has been removed in FIG. 1 in order to show the rotating links.

The rotational connections between the crankshafts and the output shaft can, alternatively and depending on the use of the engine, be made through chains or belts for example.

Claims (10)

1. Internal combustion engine, comprising at least a first crankshaft (5) linked to an output shaft (8) of said engine by means of a first rotational linkage, and a second crankshaft (6) linked to said output shaft of the engine by means of a second rotational linkage, characterised in that said first rotational linkage is reversible and comprises a first driving wheel (11) linked fully rotationally to said first crankshaft through the intermediary of a first obstacle link (13), which is able to transmit an engine force from said first crankshaft to said output shaft and is capable of breaking when there is a malfunction leading to immobilisation of said first crankshaft, under a force less than or equal to the force necessary for immobilising said first crankshaft, and in that said second rotational linkage is reversible and comprises a second driving wheel (25) linked fully rotationally to said second crankshaft through the intermediary of a second obstacle link, which is able to transmit an engine force from said second crankshaft to said output shaft and is capable of breaking when there is a malfunction leading to immobilisation of said second crankshaft, under a force less than or equal to the force necessary for immobilising said second crankshaft.
2. Engine according to claim 1, characterised in that it comprises at least a third crankshaft (7), a third rotational linkage, a third driving wheel (26), and a third obstacle link.
3. , Engine according to claim 1 or 2, characterised in that said first and second rotational linkages, at least, are gear linkages.
4. Engine according to one of claims 1 to 3, characterised in that at least said first obstacle link comprises a first shearing cotter-pin, peg (13) or the like, and said second obstacle link comprises a second shearing cotter-pin, peg or the like.
5. Engine according to claim 4, characterised in that at least said first obstacle link additionally comprises a first driving abutment (14) which is able to transmit said engine force from said first crankshaft (5) to said output shaft (8), and said second obstacle link additionally comprises a second driving abutment which is able to transmit said engine force from said second crankshaft to said output shaft.
6. Engine according to claim 5, characterised in that said first (14) and second driving abutments, at least, respectively comprise at least one asymmetrical tooth (15), which is kept in engagement in a recess (16) of complementary shape by means of said shearing cotter-pin, peg (13) or the like.
7. Engine according to claim 6, characterised in that said asymmetrical tooth (15) comprises a first face (17), which is able to transmit said engine force, and a second face (18), opposed to the first, permitting an engagement of said asymmetrical tooth in said recess (16) to be avoided in the event of said shearing cotter-pin, peg (13) or the like breaking.
8. Engine according to claim 6 or 7, characterised in that at least said first driving abutment (14) comprises a plurality of teeth (15), which form a first crown extending in a first plane perpendicular to a longitudinal axis of said first crankshaft (5), and said second driving abutment comprises a plurality of teeth, which form a second crown extending in a second plane perpendicular to a longitudinal axis of said second crankshaft.
9. Engine according to one of claims 1 to 8, characterised in that said first (11) and second (25) driving wheels, at least, are in engagement with a fourth driven wheel (12) which is fully rotationally linked to said output shaft (8).
10. Engine according to claim 9, characterised in that said first (11) and second (25) driving wheels, at least, and said fourth driven wheel (12) are situated substantially in one and the same plane.

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