EP0052387B1 - Motor with at least one linear-translationpiston and wobble plate - Google Patents

Abstract

1. An engine having at least one piston for linear reciprocating movement in a combustion chamber and a wobble plate mounted on a shaft and inclined at an angle thereto, the shaft being arranged to be rotated in the crank case or engine block by the alternating movements of the said plate in contact with the said piston, the latter being fixed to a piston rod (10), the end of the piston rod opposite to the piston comprising a slide block (11) guided in a sliding guide which forms part of the engine block and of which the geometrical axis coincides with that of the said piston rod, the said slide block having two seating members (18 - 18') trapped within it, said seating members constituting a housing for a spherical coupling element (19) connected by a neck to the said wobble plate (20) and projecting laterally with respect to the said wobble plate, means being provided for causing the volume of the said combustion chamber to be varied, characterised in that one, and only one, end of the said shaft (29) is mounted in a bearing preventing axial displacement of the said shaft with respect to the engine block, the other end of the same shaft, mounted in a plain bearing, being provided with a fly wheel (33) comprising two concentric elements (34 - 35) the inner one of which has a central cylindrical protion (39) adapted to bear on the said wobble plate (20), a volumetric chamber being provided for causing the space separating the two concentric elements of the said fly wheel to be varied.

Description

The invention relates to an engine comprising at least one piston with reciprocating linear transmission movement in a combustion chamber and a swash plate mounted at an angle on a shaft driven in rotation in the casing or the engine block by the reciprocating movements of said plate. contact with said piston, the latter being integral with a piston rod whose end situated opposite the piston and comprising a slide guided in a slide forming part of the engine block and whose geometric axis coincides with that of the aforementioned connecting rod, the aforementioned slide trapping two shells constituting a housing for a ball joint connected by a neck to the aforementioned swash plate and extending laterally relative to said swash plate, means being provided for varying the volume of said combustion chamber.

A pressure generator related to this type of engine is described in US Pat. No. 4,202,251.

In the French patent 1 090409 which relates to a gas generator constituted by groups of opposite pistons, arranged in barrel, is approached the problem which consists in ensuring to the whole of the pistons a stroke of constant length but of variable origin according to the position of a part which can slide axially in the engine box.

Unlike this system, which is considered to be too rigid, the invention aims to allow automatic adjustment of the ratio between the compression ratio and the number of revolutions of the shaft mentioned in the preamble.

In order to achieve this objective in accordance with the invention only one end of the aforementioned shaft is housed in a bearing opposing an axial displacement of said shaft relative to the engine block, the other end of the same shaft, housed in a bearing smooth, being equipped with a flywheel consisting of two concentric elements, the one of which located on the internal side has a central cylindrical body intended to bear on the aforementioned swash plate, a volumetric chamber being provided for varying the space separating the two concentric elements of said flywheel.

Still according to the invention, the aforementioned flywheel consists of two elements, one of which is fixed on said shaft and the other can slide axially thereon, defining between them said volumetric volumetric chamber, so that the element mobile which abuts against the aforementioned swash plate can move it to vary the volume of the combustion chamber remaining between two pistons with opposite translational movement.

• La figure 1 est une vue partiellement en coupe longitudinale et partiellement en élévation d'un moteur selon l'invention.
• La figure 2 est une vue explosée montrant un piston et son système de guidage dans un cylindre faisant partie du bloc moteur ainsi que la partie latérale du plateau oscillant selon l'invention.
• La figure 3 est une vue schématique illustrant la course d'un galet monté sur un tourillon posé dans l'axe géométrique reliant les deux rotules d'un même plateau.
• La figure 4 est une vue en perspective schématique d'un plateau équipé de deux rotules et d'un galet circulant entre deux profilés de guidage.
• La figure 5 est une vue analogue d'une variante dans laquelle le plateau oscillant est équipé de quatre rotules.
• La figure 6 est une coupe selon la ligne VI-VI de la figure 1.
• La figure 7 est une coupe analogue mais se rapportant à un plateau oscillant à deux rotules.
• La figure 8 est une coupe, à une plus grande échelle, d'un plate au oscillant, coupe comprenant l'axe géométrique du plateau.
• La figure 9 se rapporte à un volant à masselottes centrifuges vu selon une coupe radiale.

Other details and advantages of the invention will emerge from the description which will be given below of an engine or similar machine and of the swash plate intended to equip such an engine or a similar machine.

• Figure 1 is a view partially in longitudinal section and partially in elevation of an engine according to the invention.
• Figure 2 is an exploded view showing a piston and its guide system in a cylinder forming part of the engine block and the side part of the swash plate according to the invention.
• Figure 3 is a schematic view illustrating the race of a roller mounted on a pin placed in the geometric axis connecting the two ball joints of the same plate.
• Figure 4 is a schematic perspective view of a plate equipped with two ball joints and a roller circulating between two guide profiles.
• Figure 5 is a similar view of a variant in which the swash plate is equipped with four ball joints.
• Figure 6 is a section along line VI-VI of Figure 1.
• Figure 7 is a similar section but relating to an oscillating plate with two ball joints.
• Figure 8 is a section, on a larger scale, of a flat oscillating, section comprising the geometric axis of the plate.
• Figure 9 relates to a flywheel with centrifugal weights seen in a radial section.

The engine according to the invention comprises, in its embodiment according to Figure 1, an engine block in which move, two by two and in opposition, cylinders 2 ', 2 "and 3', 3". Inlet lights have been represented schematically by the references 6 and 7. The references 4 and 5 relate to the exhaust lights of the cylinders in which the pistons 2 'and 2 "and 3" and 3 "move. Lights 4 and 5 lead to a common collector. Lights 6 and 7 open onto a common manifold per cylinder.

It is recalled that the engine according to the present application in principle comprises at least one cylinder, that FIG. 1 relates to a type of engine in which two cylinders in opposition are provided twice but that, in other variants to which it will be alluded to later, the engine may have four times two cylinders.

The combustion of the gas mixture in each of the chambers 8 or 9 is done by known means and which will not be described in the context of the present application since the type of combustion is foreign to the object of the invention.

To obtain a rigorous linearity of the pistons 2 ', 2 ", 3' and 3", each piston is rigidly connected to a connecting rod 10. The mounting elements of this connecting rod and of the slide which is associated with it make in particular the object of Figure 2 in which an exploded view of the cylinder 2 'and the elements with which cooperate its guide members is shown.

With particular reference to the figure 2 it will be seen that the connecting rod 10 is connected to a slide 11 having a central housing offering two parallel walls 12 terminated by a cover 13 which is tightened on the slide 11 using four screws 14 which pass through four orifices 15 and are screwed in plate 13 '. The slider 11 is guided in a cylinder 16 which can, in practice, constitute a cylindrical cavity of the engine block but which has, in any case, a first slot 17 whose width is sufficient to allow the movements of the swash plate. The width of the housing between the faces 12 of the slide is equal if not slightly greater than the width between parallel faces of the shells 18 intended to trap, two by two, a ball joint 19 of the swash plate shown diagrammatically under the reference 20.

The shells 18 - 18 'adapt to one another thanks to the pins 21 provided on one of the shells to penetrate into orifices, not visible in the drawing, provided on the shell mounted in opposition.

In an engine with one or two ball joints, the oscillating movement of the plate takes place in a single plane passing through the plane of symmetry of the housing and therefore also through the geometric axis of the connecting rod 10.

In the case of an engine equipped with an oscillating plate with two ball joints, the shells 18 - 18 ', trapping the ball joint 19, slide without play along the faces 12' of the abovementioned housing.

In the same engine whose swash plate is equipped with two ball joints for two sets of two cylinders, there is provided, in the extension of the neck 22 of the ball joint 19, a pin 23 (Figure 4) equipped with a roller 24 trapped between guide profiles 25. The purpose of the guide profiles 25 between which the roller 24 circulates is to prevent the rotation, about its geometric axis, of the swash plate 20. The rotation of a piston, in this case the piston 2 ′ of FIG. 2 is prevented by the presence on the cover 13 of the slide 11 of a pin 26 with a roller 27, trapped between the opposite faces of the longitudinal slot 28, provided in the cylinder 16, opposite the wide slot 17. It should be noted that no lateral force is exerted either on the slide or on the connecting rod.

The shells 18 - 18 'and the roller 27 are still perfectly visible in the part of Figure 1 which constitutes a longitudinal section.

In the case of an engine with four pairs of pistons and therefore with four ball joints, the pin 22 'with roller 23' is placed between two ball joints 19 (FIG. 5).

Referring once again to FIG. 1, it will be noted that in this embodiment two sets of two pistons are in mutual opposition, the pistons 2 - 3 'acting by connecting rods 10 and slides 11 on the ball joints , not visible in the upper part of the figure, belonging to the oscillating plates represented by the general reference 20. The rollers 27 as well as the opposing slots 17 and 28 are also visible in this upper part of Figure 1.

The swash plate 20 is wedged on a shaft 29 mounted in a ball bearing 30.

The second inclined plate constituted by the lower plate represented in section in FIG. 1 under the general reference 20 ′ is mounted on the same axis but according to an assembly which prevents its rotation relative to the axis but not to a certain longitudinal sliding . Such an assembly, known per se, is achieved by the presence of an edge 31 provided on the shaft 29 to cooperate with a recess of the elements constituting the swash plate 20 '.

This plate, which consists of the same elements as the swash plate 20, will be described in detail below and constitutes an essential element of the invention.

The motor axis 29 is, opposite the ball bearing 30, mounted by means of a plain bearing 32 in the opposite face of the motor unit 1. This end of the shaft 29 is equipped with a flywheel bearing the general reference 33, consisting of two coaxial elements 34 and 35. The element 34 fixed on the shaft 29 has a circular groove 36 for the circular edge 37 of the element 35 of the steering wheel 33.

In opposition to the element 34 of the steering wheel, the element 35 can, thanks to a mounting known per se, slide slightly along the shaft 29 but cannot be rotated relative to this shaft. The rotation of the shaft 29 and the element 35 of the flywheel 33 are obviously integral.

Between the elements 34 and 35 of the flywheel 33 there remains a space 38 for a hydraulic fluid whose pressure can be increased or reduced at will. By increasing the pressure of the hydraulic fluid in the space 38, the swash plate 20 ′ acts via the cylindrical body 39. In fact, it can be seen that the swash plate 20 ′ abuts, in its central part, on the transverse face of the cylindrical body 39 which is integral with the steering wheel element 35.

We can easily understand that by varying the volume of space 38 we act on the inclined plate 20 'in the direction of the arrows 46' or 46 "to vary the compression between the pistons 2,2 'and 3, 3' To achieve this objective, it suffices to provide a seal impervious to hydraulic pressure between the circular flange 37 and one or more faces of the circular groove 36 of the flywheel element 34.

Another construction thanks to which it is possible to automatically adjust the ratio between the compression ratio and the number of revolutions of the motor shaft is shown in Figure 9.

The steering wheel, designated by the general reference 33, also consists of two elements, the element of which, fixed relative to the shaft 29, which bears the reference 40. This steering wheel element 40 is equipped with a series of flyweights 41 arranged in a circle inside the rim 42 of the element 40. Each counterweight is subjected to the action of a spring 43 wound on a rod 44 which serves also guide to the corresponding counterweight.

The flyweights 41 have the form of wedges, the large base of which is directed towards the periphery of the steering wheel 40 or, again, towards the rim 42 of the steering wheel element 40.

The steering wheel element 45 which is rotated by the shaft 29 can execute a certain longitudinal movement relative to this shaft, thanks to a construction which is moreover known per se.

Thanks to the centrifugal force the weights are pushed outwards against the springs 43 and there follows a displacement, according to arrow 46 (Figure 9). It follows that during an increase in the number of turns of the shaft 29 there will be a decrease in the compression ratio between the pistons working in opposition, and vice versa. Indeed, cold starting will be facilitated by the fact that the volumetric ratio is improved. In higher speed, more overeating will be made possible.

From the description which has just been given, it will be noted that the means for guiding the pistons 2'- 2 "and 3'- 3" ensure rigorous linearity in the alternating movement of the sliders 11 moving inside the slides formed by the cylinders 16 or similar cylindrical cavities forming part of the engine block. This rigorous linearity is ensured thanks, in particular, to the design of the mounting between the shells of the ball joints 19 of the oscillating plates 20 or 20 ′. When a swash plate is equipped with only two ball joints, the oscillating movement of the plate is carried out strictly in a single plane comprising the geometric axis of the shaft 20 and the geometric axis of the connecting rods 10. On the other hand, when '' a swash plate is equipped with four ball joints, each of these follows a slightly eight-way trajectory. When use is made of an oscillating plate with four ball joints, no play is observed inside the housing 12 between the base of this housing, forming the base of the slide and the underside of the cover 13 (FIG. 2). On the other hand, there is a play between the parallel faces 12 of the housing as well as a back-and-forth or translation movement inside this housing as is easily conceivable, due to the upward and downward movements of each. ball joints 19 inside each of the corresponding housings of the slides 11.

The design of the swash plates 20 - 21 is such that they can, without danger of fatigue which would cause premature wear of their constituent elements, be subjected to extremely high stresses. These stresses come from the forces exerted on the ball joints 19 by means of the slides 11 of the connecting rods 10 and the various pistons 2'- 2 "and 3'-3".

Referring more particularly to FIG. 8, it will be noted that the swash plate consists of a ring 47 carrying at least two diametrically opposite ball joints 19 joined to the ring 47 by a collar 22. The ring 47 is mounted on a central bush 48 by by means of a first needle bearing 49 and by a second needle bearing 50. The needle bearing 50 is held in position on the corresponding lateral flank of the crown 47 by a circular element 51.

The cylindrical elements of which the needle bearing 49 is made up are alternately composed of two and three coaxial elements. This arrangement is provided to take account of the variations in angular speed which these elements undergo when considering the rotation of the central sleeve 48 with respect to to crown 47.

The central bush 48, the internal diameter of the central bore corresponds to the external diameter of the shaft 29, has two external flanks 52 and 53 which are mutually parallel as well as with the plane of symmetry of the crown 47 at height the center line 54. However, on the side where the swash plate comes into contact with the cylindrical body 39 of the flywheel, when it is the swash plate which, according to Figure 1, cooperates with the movable flywheel element 35, the flank 52 of the central sleeve is cut by a plane which extends at right angles to the geometric axis of the shaft 29. This plane is given in FIG. 8 the reference 55. The part of this plane which is in permanent contact with the external face of the cylindrical body 39 is indicated in solid lines by said reference 55 in FIG. 8 where the reference 56 indicates a parallel plane cut at an angle to with respect to the external flank 52. We also note at Figure 5 the edge 31 which forces the rotation of the sleeve the central unit 48 of the swash plate and allows the axial displacement of the assembly relative to the shaft 29.

A third needle bearing, or, in the case of pressure lubrication, a plain bearing, forming a circular crown inside the crown 47 is represented by one of these elements under the reference 56. Balancing means constituted by orifices 58, on the one hand, and bolts 59, on the other hand, are provided in the outer sides 52 and 53 of the central ring 48.

From the description which has just been given of the swash plate according to the invention, it will be realized that it has all the qualities of compactness and therefore robustness which are necessary to enable transmission, from the pistons of the engine and via the ball joints 19, the forces extremely important to the central bush 48 mounted on the shaft 29 to cause the rotation thereof.

The forces to be exerted from the various pistons on the swash plate shown in FIG. 8 and supposed to be the bottom swash plate according to FIG. 1 are exerted on the ball joints 19 in the direction indicated by the arrows 57.

The extremely large forces exerted in the direction of the arrows 57 on the ball joints 19 could not be transmitted to the shaft 29, via a central sleeve 48 without using a needle bearing designed in the form which has been described above. In FIG. 8, one of the ball joints 19 has a threaded axial bore into which a pin 23 carrying a roller 27 can be screwed, as these elements have been represented in FIG. 4.

Claims (10)

1. An engine having at least one piston for linear reciprocating movement in a combustion chamber and a wobble plate mounted on a shaft and inclined at an angle thereto, the shaft being arranged to be rotated in the crank case or engine block by the alternating movements of the said plate in contact with the said piston, the latter being fixed to a piston rod (10), the end of the piston rod opposite to the piston comprising a slide block (11) guided in a sliding guide which forms part of the engine block and of which the geometrical axis coincides with that of the said piston rod, the said slide block having two seating members (18 18') trapped within it, said seating members constituting a housing for a spherical coupling element (19) connected by a neck to the said wobble plate (20) and projecting laterally with respect to the said wobble plate, means being provided for causing the volume of the said combustion chamber to be varied, characterised in that one, and only one, end of the said shaft (29) is mounted in a bearing preventing axial displacement of the said shaft with respect to the engine block, the other end of the same shaft, mounted in a plain bearing, being provided with a fly wheel (33) comprising two concentric elements (34 - 35) the inner one of which has a central cylindrical protion (39) adapted to bear on the said wobble plate (20), a volumetric chamber being provided for causing the space separating the two concentric elements of the said fly wheel to be varied.

2. An engine according to Claim 1, characterised in that the said fly wheel (33) comprises two elements one of which is fixed on the said shaft, the other one being arranged to slide axially on the shaft, so as to define between them the said volumetric chamber volumetrically, in such a way that the movable element which makes a butting contact against the said wobble plate can displace the wobble plate so as to cause the volume of the combustion chamber existing between two opposed reciprocating pistons to be varied.

3. An engine according to either one of Claims 1 and 2, characterised in that the volumetric chamber comprises a chamber subjected to a variable hydraulic pressure.

4. An engine according to Claim 2, characterised in that the said volumetric chamber is provided with centrifugal segments (41) in the form of wedges, the larger end of which is directed towards the outside, while the inner surfaces of the elements of the fly wheel that face each other are inclined with respect to the engine shaft, at an angle which corresponds to the cone angle of the segments, the arrangement being such that an increase in the centrifugal force acting on the said segments causes the elements of the fly wheel to move closer together, whereby the combustion chamber between two pistons working in alignment with each other is enlarged.

5. An engine according to any one of Claims 1 to 4, characterised in that it includes a wobble plate comprising a ring (47) carrying externally at least one, but preferably two or four, sperical coupling elements (19) each of which is adapted to engage on a piston movable in linear reciprocating movement, and further comprising a central boss (48) having a bore the geometrical axis of which makes an angle with the plane of symmetry of the said ring, the said central boss (48) being rotatably mounted with respect to the said ring by means of two needle bearing (49 - 50), which are disposed on either side of the said ring for allowing the needles of the bearings to roll with respect to, on the one hand, an annular projection of teh central boss and, on the other hand, an annular element mounted on the said boss.

6. An engine according to Claim 5, characterised in that each cylindrical element for rolling engagement with the said needles is, at least during the rolling movement, mounted between the said ring and the said projection of the boss, comprising at least two halves disposed coaxially.

7. An engine according to one of the Claims 1 or 6, characterised in that the inner circular face defining the central opening of the said ring is provided with a needle bearing race.

8. An engine according to one of Claims 5 or 6, characterised in that the inner circular face defining the central opening of the said ring is provided with a plain bearing when pressure greasing is provided.

9. An engine according to any one of Claims 5 to 8, characterised in that the outer flanks of the said central bush are provided with balancing means.

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