HK1188272A - Radial cylinder hydraulic machine with improved oscillating radial cylinder - Google Patents

Description

Radial cylinder hydraulic machine with improved oscillating radial cylinder

Technical Field

The present invention relates to radial cylinder hydraulic machines of the type well known in the art, that is to say ideally oscillating cylinders, for which the cylinders are placed in a star and all act on the same eccentric crankshaft or crankshaft crank, these cylinders being placed in oscillation compared to the machine body. As mentioned in the attached description, oscillating radial cylinders have ideal characteristics compared to the technical description of radial hydraulic machines, in order to obtain a technical and economic effect that is important compared to said technical description.

Background

The state of the art includes various types of radial hydraulic machines with cylinders placed in a star, and in particular radial hydraulic machines in which a single cylinder, near the outer diameter of the casing of the machine, oscillates about an axis in order to carry out the oscillation required by a crankshaft in contact with the cylinder and running with the rotary motion of the cylinder. As a cylinder-piston element, this oscillation is necessary, even if it is also dependent on the capacity to perform (capacityexcitation) an alternating action, which acts as a "pusher rod" in the mechanical concept of the crank gear of the pin and therefore of the eccentric stroke of the crankshaft; thus, the so-called "rod" has a variable length depending on the volume which varies with the movement of the liquid towards or away from the oscillating radial cylinder in question. The respective pistons are placed in such a way as to roll along the outer surface of the elbow or eccentric, or to rotate around it, between the interposed concentric elements.

In the present technique, as described above, these hydraulic machines are built with various support methods for cylinder oscillation: the first method is by means of side trunnions (side trunnions) placed on the axis of oscillation parallel to the axis of the crankshaft and close to the outer shell (i.e. the shell) of the machine, which allow the passage of the hydraulic oil through one trunnion in order to place the most bulky part of the cylinder, the sleeve and the outer shell away from the bell crank and to obtain a greater flow rate of the same size, whereas the passage of the hydraulic oil in the trunnion makes the high working pressure weak, which is now particularly common in the field of such hydraulic machines; a second method of oscillating the cylinder-piston elements in the hydraulic machine is to place the cylinder-piston elements on the surface of a ball for each cylinder, the surface of the ball being placed close to the outer diameter of the envelope of the hydraulic machine. The part sliding on the bend or on the eccentric of the crankshaft in the direction of the axis of rotation is located on a spherical surface of a circular ring, thus presenting in all cases a sliding surface area with a preferably flat condition of the piston elements of the cylinder, which obviously corresponds to the flat condition of the spherical surface obtained at the outermost diameter, thus supporting the thrust generated in the cylinder due to its alternating movement inside the piston. In fact, in this second method, the technique also comprises the implementation, in which the piston is placed close to the outer diameter of the shell and the cylinder is placed close to the inner diameter, thus close to the sliding diameter on the eccentric or on the crankshaft, with a significant deterioration in size and with an alternating movement produced by the cylinder instead of by the piston.

It is known that the first method of oscillation of the cylinder-piston element presents a critical point at the oscillation surface of the trunnion, since the thrust generated by the hydraulic liquid in the cylinder is transmitted to the envelope through said trunnion, and at the same time at least one trunnion must be hollow, in order to allow for the passage of the hydraulic liquid. Therefore, the structure of the coupling of the trunnion with the shell is very difficult and expensive, and the performance and support according to the thrust generated is also very limited due to the weakness of one of the trunnions. Furthermore, in such a hydraulic machine, in which the variable capacity is at a minimum value rather than absent, the oscillation range of the trunnions is drastically reduced without reducing the thrust on the trunnions, so as to limit the value of the thrust to the minimum flow rate and therefore the power and torque achievable by the minimum capacity of the engine capable of variable capacity.

In fact, an important advantage of the radial cylinder hydraulic machine, which generally yields better performance compared to other types of well-known hydraulic machines, is that, depending on the dimensions, it has a huge capacity, so that it is possible to make a high coupling (coupling) without the need to work at an ultra-high pressure of the hydraulic liquid, and at the same time to work at high rotation speeds, and therefore to make maximum flexibility of use, which was previously not possible with other types of hydraulic machines. Another limitation indicated in the present specification focuses on: the addition of port passages and power channels and/or hydraulic fluid drainage, which is currently not possible unless the dimensions are present; a reduction in the length of the channel itself, and therefore in the harmful volume of the usual noise generation, with consequent energy losses due to the constant variation of the pressure of the liquid column held in the channel; the external dimensions of the machine, having the same capacity and mechanical properties, are reduced, which is preferable for the user, since the machine is easy to insert in a limited space and is reduced in size.

In the art, document US3,695,146 is known, describing a hydrostatic motor with radial cylinders that vary by the varying capacity of the eccentricity of the crank. Each cylinder has a spherical oscillation surface through which a channel of hydraulic liquid passes under pressure, the supply of hydraulic liquid being effected for each cylinder from a single slide valve distributor. The variation of the eccentricity of the crank also involves the adjustment of the eccentric that controls the slide valve. A similar structure developed for obtaining high rotation speeds at minimum flow rates loads the oscillating surface with a radial thrust, which, due to the pressure of the liquid and in proportion to this pressure, results in a higher pressure generating a higher thrust of the oscillation assumption of the cylinder in its spherical housing. Finally, the spherical oscillation surface and the sliding housing on the eccentric crank are intentionally spherical to maintain the alignment of the piston on the eccentric.

Furthermore, also known in the art is the document fr1.530.605, which describes a hydraulic motor with oscillating radial cylinders having a spherical oscillating surface and in which the introduction ports and the hydraulic liquid discharge ports, suitably placed in the oscillating arch, are found. The cylinder oscillation generates a hydraulic fluid distribution relative to the cylinder. Thus, even if the feeding of the cylinders does not take place using the axial channels of the cylinders, the size of the supply channels establishes the impossibility of the ratio of the motor to the higher number of cylinders 5, 7 or 9 (illustrated with only three cylinders), that is to say it is known to generate a more regular driving torque, thus preventing a smaller size from being achieved compared to other hydraulic machines for a similar performance level. As with the above-described motors, hydraulic motors are disadvantageous because the pressure of the high sphere is different from one side to the other due to the distributing effect the sphere has as the cylinder oscillates in order to maintain unbalanced thrust on the spherical surface.

In the second method of oscillation with cylinders equipped with axial channels of the cylinder-piston element, the feeding takes place from the outside of the spherical oscillation surface, whereby the passage of hydraulic liquid to and from the cylinders takes place, whereby it must be created by increasing the diameter or size of the shell, in order not to take into account the volume and the limitations of the dimensions of the hydraulic machine that become cleaner and less favourable, in particular when large dimensions are to be created, even large cylinders and high hydraulic liquid flow rates across the hydraulic machine. Therefore, if the aim is to reduce the radial dimensions, the dimensions of said channels are limited both in the case of feeding the cylinder through the trunnion and in the case of feeding the cylinder through the oscillating surface.

Now therefore, in a second method of supporting the oscillation of the radial cylinders, as mentioned above, the spherical surface is wide and is formed in such a way as to contain the auditory canal (media) of the hydraulic liquid, so as to obtain the hydrostatic support of the cylinder block, resting on the spherical surface formed or applied to the casing layer of the hydraulic machine. This hydrostatic support of the ear canal is not working in very good conditions, since the hydraulic liquid is collected inside the ear canal, especially when the angle of oscillation of the cylinder is reduced, during the control of the volume change due to the variable volume of the hydraulic motor according to the operation at minimum volume: the ear canal must have a toroidal surface with a pressure of sufficient magnitude to function correctly, whereas the pressure of the hydraulic liquid is present itself during the use of the hydraulic machine, as usually happens in engines forced to operate with minimum capacity, so that the ear canal is made with a surface of greater size in order to reduce the passage section of the hydraulic liquid that occurs inside the spherical surface of the circular ring of oscillation, as mentioned above.

Furthermore, in the present art, also known from document EP0491398a1, which describes the effect of the pressure of the hydraulic liquid in the coupling between the spherical oscillation surface of the piston in a radial hydraulic motor and the axial supply through the spherical oscillation surface, it is confirmed that the oscillation surface on the oscillating element must be small compared to the oscillation surface on the body or shell of the motor. However, in the case where there is a large surface in contact with the rocking, this confirms how the excessive ear canal liquid formed on the ear canal side must be drained through the drainage channel inside the spherical rocking surface. As in the case of the previous document, the high pressure and low degree of oscillation that can be obtained when the oscillating movement does not determine the discharge of the liquid contained in the spherical section in contact with the oscillation generates the assumption: there is therefore a need for an easy clean-up (clean) to replace the hydraulic liquid in the ear canal.

Finally, document WO03/078822a1 is known, describing a method of oscillation of the sliding shoes (slide shoe) on the eccentric of the high-pressure pump and of the inline liquid cylinder level. The shoe acts as a short bar to create the significant angular offset. The suction channel in the eccentric of the crank is supplied with electricity in the axial direction with a hollow piston and each batch pushes liquid through the non-return circuit valve. The contact of the piston and the slide (runner) occurs at spherical surfaces, one spherical surface having a wider radius to make initial contact with a wide spherical contact zone between the piston and the slide due to plastic yielding of one of the two materials of the piston or slide into contact within the zone. This work is facilitated and compensated by a spring inside the piston which restores the plastic yield obtained in the first-use coupling, so as not to constrain the contact band to the circumference.

With regard to the possibility of creating an ideal radial hydraulic machine, the state of the art is apt to further improve the oscillating cylinder type, which goes beyond the above mentioned problems, and functions according to the reduction in size and quality of the spherical contact between the cylinder and the body or casing of the hydraulic machine.

Therefore, there is a technical problem, according to the present invention, of creating an ideal radial hydraulic machine with a version of oscillating cylinder in which the cylinder-piston group is in contact with the engine block, or envelope, creating a ball-type contact size when the aim is to create a greater flow rate and/or a high flow rate of liquid, so as not to increase the external dimensions of the machine inefficiently, whereas the ideal technical advantages sought after the reduction in size can be obtained considering the variations already obtained with radial cylinder hydraulic machines and with the implementation of the oscillating ball-type contact.

Another, but not last object of the present invention, is to consider the formation of a radial hydraulic machine with oscillating cylinders in which the reduction in size with the same capacity or, conversely, with the same size, with the increase in capacity obtained, makes it possible to reduce the harmful levels present in the power/discharge pipes to and from the cylinders.

Finally, another part of the technical problem explained above relates to the formation of an ideal radial hydraulic machine of the oscillating cylinder type, in which the section of the power/discharge pipe of the cylinder can be increased in order to make it easier to make an effective passage of the hydraulic liquid from the liquid tank (plant) to the cylinder and vice versa, with the aim of considering the possibility of forming a greater flow rate than in the constructive solutions indicated in the technical specifications.

Disclosure of Invention

According to the invention, this problem is solved by a radial cylinder hydraulic machine comprising: oscillating radial cylinders, close to the outer shell of crown and star cylinder (i.e. finger cylinder) -piston groups; the pistons of said set start sliding on a crankshaft or eccentric, or on concentric insertion elements, and create an alternating motion in oscillating radial cylinders; and is characterized in that said oscillating cylinder is placed in contact with a spherical oscillating surface formed or included in the hydraulic machine body or in the casing; each oscillating radial cylinder is equipped with an internal circular surface having a curvature greater than the radius of the spherical oscillating surface, for coupling with said spherical oscillating surface, so as to form a contact at a circumference having a bandwidth, due to the only elastic yielding of the material in the middle zone of the contact circumference; furthermore, the radius of the contact circumference is less than half the diameter of the bore of the cylinder; finally, the hydraulic machine comprises a thrust device of the oscillating cylinder against the oscillating sphere outside the cylinder itself; and preferably, the diameter of the spherical swing surface is smaller than the bore diameter of the swing radial cylinder.

In a further advantageous embodiment, the spherical surface of oscillation comprises a ring configuration which is bounded close to a central region which surrounds the circumference in contact with the inner ring surface.

Moreover, in a practical implementation, the spherical surface of oscillation has a limited annular conformation close to a median zone, in area contact in the contact circumference with an internal annular surface consisting of an internal truncated-conical surface, and at the same time said truncated-conical surface presents a limited annular conformation close to the median zone of contact with the spherical oscillation surface.

In another embodiment: both the spherical surface of oscillation and the annular surface of internal arch have an annular configuration limited to a median narrow contact area around the contact circumference between the oscillating surfaces of the hydraulic radial cylinders; the radius of the curve of the inner arcuate annular surface is greater than the radius of the spherical surface of oscillation and less than the infinite value.

Furthermore, in a further execution form that is quite advantageous, the supply and/or discharge of hydraulic liquid in the oscillating cylinder is carried out by the hydraulic liquid to and from the oscillating radial cylinder, by one side of the cylinder itself, so that the supply and discharge of the cylinder to and from the supply channel on the body or side cover of the hydraulic machine is formed at least by a laterally flat outer surface on the side of the oscillating cylinder, parallel to the oscillating surface of the cylinder; a closed ring fitted with at least contact surfaces resistant to wear on the walls of the lateral sliding surfaces, the closed ring being interposed between the side surfaces in contact, for the passage of the feed liquid under pressure.

In another embodiment: in the laterally flat outer surface parallel to and opposite to the one through which the liquid is fed, there is a thrust compensation hole, to which the liquid is fed under pressure in the oscillating cylinder, around which a closing ring is fitted with at least a cylinder surface resistant to wear on the wall of the flat side-sliding surface and which is also placed between the lateral flat surfaces in contact, for the passage of the liquid under pressure to the compensation hole.

In addition, in a specific implementation, the surface of the compensation orifice for the thrust or of the pressure effect in a recess of the flat side-slipping surface is slightly smaller than the surface of the supply orifice for the liquid under pressure in the oscillating radial cylinder.

In another constructive form, the closing ring of the sliding contact between the lateral external surfaces consists of a coupling part, in contrast to the sliding flat lateral surfaces of the oscillating radial cylinders and the cylinder block, in which: a metal ring forming a wear resistant surface on a closed side in contact with a sliding surface of the closure ring; a ring of soft pliable material interposed between the metal ring and the housing or the recess in which the closed ring is held; an anti-extrusion ring placed between the metal ring and the ring of soft pliable material, thereby avoiding extrusion of the ring due to the pressure of the liquid during operation.

In a further advantageous constructive form, moreover, a closing ring for the power aperture and/or for the compensation aperture for the thrust is held in its own casing in a ring formed in the side face of the cylinder block, and is in sliding contact against the flat side surface of the body of the radial hydraulic machine and its cover.

Furthermore, in a preferred constructive form, the respective oscillation surfaces of each oscillating radial cylinder of the cylinder-piston group are formed by a portion of spherical surface on the mechanical element close to the outer shell layer, and these oscillation surfaces are connected in a transversal movement pattern with the shell layer or with a portion of the transversal cover of the hydraulic machine, in a direction parallel to the axle of the crankshaft.

Furthermore, in a particular constructive variation, the radial cylinder hydraulic machine comprises: oscillating radial cylinders, close to crown or star cylinder-piston groups; the pistons of the set, made to slide on a crankshaft or eccentric, or on concentric insertion elements, and forming an alternating movement of oscillating radial cylinders; the oscillating cylinder placed in contact with a spherical oscillating surface formed in or comprised in the body or shell of the hydraulic machine; this is characterized in that it comprises a passage for hydraulic liquid to and from the oscillating radial cylinders, so as to form the supply and discharge of the cylinders by means of at least a flat lateral external surface of the oscillating cylinders to and from a supply channel on the body or the lateral cover of the hydraulic machine, parallel to the oscillation surface of the cylinders; a closed ring fitted with at least a contact surface resistant to wear on the wall of the side surface of the sliding surface, the closed ring being placed between the contact flat side surfaces of the passage for the incoming liquid; finally, the thrust means of the oscillating cylinder can be obtained between the spherical oscillating surfaces on the outside of the cylinder itself.

Furthermore, in a preferred constructive form, in order to maintain the contact between the oscillating surface of the oscillating radial cylinder and the body or envelope of the hydraulic machine, the thrust means on the cylinder for contact consist of at least one ring fitted with arcuate contact members, conforming to the radius of curvature compared to the oscillating surface of the cylinder on the arched connection of the thrust means, according to the respective radius of curvature of the steps on the respective cylinder, compared to the axis of curvature of the portion of spherical surface of oscillation of each cylinder.

Finally, in order to maintain the contact between the oscillating surface of the oscillating radial cylinder and the body or shell of the hydraulic machine, the thrust means on the cylinder in contact on the part intended to oscillate consist of arched wings on the side of the cylinder, consisting of an arched shell, according to the respective curve compared to the axis of the curve of said part of the oscillating surface of the cylinder-piston group.

In the implementation of the hydraulic machine with oscillating radial cylinders formed below, the features and advantages of the invention can be seen in the implementation examples given as examples and are not limited with reference to the twelve figures.

Drawings

Figure 1 shows, according to the invention, a schematic section of a diametral plane of the oscillating cylinder corresponding to the top dead centre, passing through the axis of the crankshaft of a radial hydraulic machine equipped with a feed on the side of the cylinder and a spherical oscillating surface;

FIG. 2 shows a schematic diametric cross-section of the hydraulic machine of FIG. 1 as indicated above, with the radially oscillating cylinder-piston set visible during rotation of the crankshaft;

figure 3 shows an axial schematic on the side of the oscillating spherical surface of the sole cylinder present in the radial hydraulic machine in figures 1 and 2;

FIG. 4 shows a schematic view of IV-IV of FIG. 3 for a swing cylinder on the diametral plane of FIG. 1 for a complete hydraulic machine;

FIG. 5 shows a schematic cross section of V-V of FIG. 3 of the oscillating cylinder block on a vertical plane as in FIG. 2 with respect to the crankshaft axis for a complete hydraulic machine;

figures 6 and 7 show perspective views of a cylinder with a feed on the side and surface of a spherical oscillation for a radial hydraulic machine as shown in the previous figures, according to the invention;

figure 8 shows, according to the invention, a schematic section of a diametral plane of the oscillating cylinder corresponding to the top dead centre, passing through the axis of the crankshaft of a radial hydraulic machine, equipped with a feed on the side of the cylinder,

in another constructive form, the supply is on one side of the cylinder and on the spherical oscillation surface;

FIG. 9 shows a perspective view of the radial hydraulic machine of FIG. 8 without the distributor cover, distributor and cover of the motor block to show the thrust ring on the oscillating radial cylinder for contact between the spherical oscillation surfaces with respect to the motor body;

figure 10 shows an enlarged view of a portion X of the schematic cross-section of figure 8;

FIG. 11 shows an enlarged view of portion XI of the schematic cross-section of FIG. 8;

FIGS. 12, 13, 14 and 15 show schematic views of the oscillating cylinders at the side, top and bottom for the radial hydraulic machine of the previous FIG. 8;

FIG. 16 shows a schematic cross section of XVI-XVI of FIG. 12 for the oscillating cylinder on the diametral plane of FIG. 8 for a complete hydraulic machine;

FIG. 17 shows a perspective view of a cylinder with a feed on the side for the radial hydraulic machine of the previous FIGS. 8 to 16, according to the present invention;

figure 18 shows an enlarged view of a portion XVIII of the schematic cross-section of figure 16;

FIG. 19 shows an enlarged view of a part of schematic section XI as in FIG. 8 for a spherical oscillating support for a hydraulic machine with radial cylinders according to the invention, but with axial adjustment of the power, the cylinder inside the spherical oscillating ring surface;

FIG. 20 shows, according to another constructive form of the present invention, a schematic section of a diametral plane of the oscillating cylinder, corresponding to the bottom dead center, passing through the axis of the crankshaft of a radial hydraulic machine equipped with a spherical oscillating support with limited contact, as in the case of the hydraulic machine of FIG. 1 with power also on the side of the cylinder;

figure 21 shows the parameters of the dimensions of the contact in a schematic section of the oscillating cylinder of the hydraulic machine of figures 8 and 9, equipped with a limited contact coupling in the form of a spherical truncated cone according to the invention;

FIG. 22 shows parameters of dimensions of contact with a schematic section of a generic oscillating cylinder block with axial feed comprising a hydraulic machine with oscillating radial cylinders equipped with limited contact spherical couplings, according to the invention of FIG. 19;

fig. 23 shows an enlarged view of part XI of the schematic section of fig. 8 in the case of the size of a spherical rocking surface in contact with different radii of curvature as illustrated in fig. 24 below;

fig. 24 shows a schematic section of the oscillating cylinder on a diametral plane of a hydraulic machine according to the invention with oscillating contact as in fig. 8, with parameters of the size of the oscillating contact of the spherical surface against the arched toroidal surface of the bottom of the hydraulic oscillating radial cylinder, according to another constructive form of the invention.

Detailed Description

In fig. 1 to 7, in an ideal oscillating cylinder of initial configuration, according to the invention, it can be seen that the crankshaft 1 is equipped with a bell crank or crank 2, and that on the bell crank or crank 2 there is a cylinder-piston group 4 of a hydraulic machine 5 with radially oscillating cylinders 6, an oscillating cylinder-piston 3. The piston 3 slides on the crank 2 in a known manner by means of respective rollers 7 and sealing rings 8. Each oscillating cylinder 6 is coupled with oscillation with the body 10 of the hydraulic machine 5 by means of a spherical coupling (i.e. coupling) between the mechanical elements indicated at 12 and a spherical surface 13, the spherical surface 13 being made axially so that it can be aligned in a direction parallel to the crankshaft 1 and to a concave spherical surface 14 made on the outer surface of the bottom 15 of the oscillating cylinder.

The cylinder 6 has, on two flat lateral external surfaces 16 and 17 parallel to each other, on the sides of the flat lateral parallel surfaces 16, a supply hole 18, and the supply hole 18 on the sides of the flat lateral parallel surfaces 16 and a thrust compensation hole 19 on the sides of the flat lateral parallel surfaces 17, respectively look down (overhead) on the supply channel 20, whereas the supply channel 20 is associated with the supply hole 18 in the cylinder 6 and in a compensation recess 21, the compensation recess 21 being associated with the thrust compensation hole 19 in the cylinder 6. The contact between the external transverse parallel surface 16 of the cylinder 6 and the body 10 of the hydraulic machine 5 in the compensation recess 21 is made by means of the same sealing ring 22 with metallic contact surfaces; this sliding contact takes place on flat lateral sliding surfaces 23 on the body 10 and on the cover 11, between them parallel and perpendicular to the axis of the crankshaft 1 and parallel to the plane of oscillation of the cylinder block. The hole 24 in the bottom 15 of the cylinder 6 feeds the spherical concave surface 14 of the base of the cylinder with hydraulic liquid for lubrication. Corresponding to the flat transversal outer surfaces 16 and 17, on which there will be found arched wings 25 having a curvature corresponding to the spherical surface of oscillation of the cylinder 6, the arched wings 25 being contained in respective arched housings 26 and 27 on the side of the body 10 and on the side of the cover 11 of the hydraulic machine 5, in order to maintain, when starting and in the presence of pressure of the liquid in the cylinder, the position of contact between the spherical oscillation surface 13 of the mechanical element 12 and the concave element 14 on the outer surface of the bottom 15 of the oscillating cylinder 6. The mechanical element, indicated with 12, with the spherical oscillation surface 13 is made mobile, by means of a sliding pin coupling 28, over a short distance in the vertical direction with respect to the oscillation plane of the oscillating cylinder 6, allowing the adjustment of the contact between the flat transversal external surfaces 16 and 18 and the flat lateral sliding surfaces 23 on the body 10 and cover 11 of the hydraulic machine 5, so as to form the best possible seal between the flat transversal external surfaces 16 and 17 and the sealing rings 22 in the housing 29 of the body 10 of the hydraulic machine 5 and in the compensation recesses 21 in the cover 11 of the hydraulic machine 5.

In fig. 8 to 18, which show a second embodiment of an ideal oscillating cylinder, the oscillating cylinder-piston group 30 of a hydraulic machine 31 with radial oscillating cylinders 32 can be seen according to the invention, with the exception of the previously mentioned and appropriately numbered elements for the previous embodiment. Each oscillating cylinder 32 is coupled in oscillation with the body 33 of the hydraulic machine 31 by means of a coupling by means of a mechanical element 34 applied to an annular spherical surface 35, which spherical surface 35 is made axially so that it can be aligned in parallel with the crankshaft 1 and with an internal conical surface 36 made on the outer surface of the bottom 37 of the oscillating cylinder 32.

On the two flat lateral external surfaces 38 and 39 parallel to each other, the cylinder 32 has, on the side of the flat parallel lateral external surface 38, a supply hole 40 and, on the side of the flat parallel lateral external surface 39, a similar hole 41 for compensating the thrust: these two parallel flat lateral outer surfaces are looking down on similar flat lateral sliding planes 42 and 43 on the body 33 and on the cover 44 of the hydraulic machine 31 connected to the assembly. The contact between the flat sliding side surface 32 on the cover 44 and the corresponding flat lateral outer parallel surface 40 takes place on a metal contact surface by means of a sealing ring 45; in the same way, the contact between the flat sliding side surface 42 on the body 33 of the hydraulic machine 31, on the opposite side of the cylinder 32, is performed by the same sealing ring 45 with a metallic contact surface. In correspondence of the flat lateral external surfaces 38 and 39, on both surfaces, at the bottom of its edges, there are arched steps 46, the steps 46 having a curve corresponding to the spherical annular oscillation surface 35 of the cylinder 32, contained in respective arched elements 48, these arched elements 48 being made in a ring 48 for each side of the cylinder piston group 30, the purpose of which is to maintain, in the absence of liquid pressure in the cylinder at the moment of activation, the contact position between the oscillating spherical annular surface 35 of the mechanical element 34 and the frustoconical internal surface of the bottom 37 of the oscillating cylinder 32. The mechanical element indicated 34 with the spherical oscillating annular surface 35 has been made movable so as to allow, through a short length of the sliding coupling 49 in the direction perpendicular to the plane of oscillation of the oscillating cylinder 32, the adjustment of the contact between the flat transversal external surfaces 38 and 39 and the flat sliding side surfaces 42 and 43 on the body 33 and cover 44 of the hydraulic machine 31, so as to create the best possible seal between the flat transversal external surfaces and the sealing rings 45 in the respective housings 50 of the oscillating cylinders.

The sealing ring 45, as can be better seen in fig. 10, is a composition between a ring made of soft pliable material 41 of circular section, also called "O-ring", an anti-extrusion ring 52 and a metal contact ring 53, the ring made of soft pliable material 41 being provided in the housing 50 for each of the two transverse holes of the cylinder 32, with the purpose of sliding against the flat side surface 42 or 43 on the side of the body 33 or on the side of the cover 44 of the illustrated hydraulic machine 31.

In correspondence to the feed holes 40, in a cover 55 as can be seen in fig. 8, there is a feed channel 54 connected to a rotating disc distributor 55 of the type known in the art, the rotating disc distributor 55 being positioned to rotate synchronously with the crankshaft 1 by means of a front coupling 56, also known as such.

According to the invention, the support between the oscillating cylinder and the body or casing of the hydraulic machine can also be formed in a known manner, wherein the supply channel of the cylinder passes through a known oscillating spherical surface. Figures 19 and 22 illustrate a known application of the above-mentioned feed, with a bearing in oscillation of the cylinder according to the invention, in which: the piston 3 is made to slide in the oscillating cylinder 57; the cylinder 57 is equipped with a bottom 58, on the surface of which 58 there is an internal annular truncated conical surface 36, this conical surface 36 being placed in contact with the annular spherical surface 35, while the annular spherical surface 35 is formed on an element 59 or by the body or casing 33 of the hydraulic machine, in which the feeding is carried out in known manner through a channel 60, the channel 60 being formed close to the axis of the spherical annular surface 35. This oscillating cylinder 57 also comprises thrust means for the oscillating cylinder against spherical oscillating surfaces, not shown in fig. 22, on the two external sides of the oscillating cylinder 57, the purpose of which is to maintain the position of contact between the spherical oscillating annular surface 35 on the mechanical element 59 and the internal truncated-cone-shaped surface 36 of the bottom 58 of the oscillating cylinder 57, at start-up and in the absence of pressure of the liquid in the cylinder.

The size of the spherical annular surface should be provided in a ratio according to the cylinder diameter D or the inner diameter, and thus the diameter D1 of the spherical oscillating surface in contact therewith should be smaller than the diameter D of the inner diameter of the oscillating cylinder 32 or 57. Furthermore, the half-opening angle β of the frustoconical annular surface 36 should be between sexagesimal 4 ° and 60 °, so as to be able to dimension the radius R1 so that the circumference close to the contact between the two annular spherical and frustoconical surfaces of the mid-zone 61 of the frustoconical annular surface 36 can be at a radius R2 limited to the width of the elastic deformation of the material.

Figures 20, 23 and 24 illustrate a hydraulic machine 62 with oscillating radial cylinders similar to figure 1, in which parts with the same function are indicated by the same reference numerals as in figure 1. The cylinder-piston group 63 is here formed by a cylinder 64 and by a piston 3 fitted with a roller 7, the roller 7 sliding on the crank 2 and being kept in contact with the crank 2 by means of a sealing ring 8. In order to form the thrust means for contact on the spherical oscillation surface 65, the cylinder 64 has arched wings 25 inside an arched housing 26, the arched housing 26 being formed from the body 10 and the associated cover 11 of the hydraulic machine 62.

Also, as can be seen in fig. 23 and 24, with reference to the hydraulic machine shown in fig. 8, each oscillating cylinder 66 is oscillatably coupled with the body 33 of the hydraulic machine by means of a spherical coupling between a mechanical element 67 with a spherical annular oscillating surface 65 and an internal arched annular surface 68 formed on the outer surface of the bottom 69, the spherical annular oscillating surface 65 being formed axially so as to be aligned parallel to the crankshaft 1, wherein the spherical oscillating annular surface 65 is made mobile as described above, so as to allow adjustment of the contact between the flat parallel transversal outer surfaces 16 and 17, or 42 and 43, and the sliding surfaces 56 and 57 on the body 33 or 10 and the cover 44 or 11 of the hydraulic machine, by means of a sliding coupling with the pins 28 or 49, so as to adjust a short distance in a direction perpendicular to the plane of oscillation of the oscillating cylinders, so as to form the best possible seal between the flat transversal outer surfaces and the sealing rings 22 or 45 in the respective housings or covers of the hydraulic machine .

In this further form of performing the contact with the spherical oscillation surface 65, the inner arched annular surface 67 should be dimensioned according to the diameter D or inner diameter of the cylinder, and therefore the diameter D1 of the spherical oscillation surface 65 in contact therewith should be smaller than the hole diameter D of the oscillating cylinder. Furthermore, the curvilinear radius R3 of the inner arched annular surface 67 should be greater than the radius R1 of the relevant diameter D1, otherwise no contact limited to the circumference is formed, and corresponding to a frustoconical surface, less than the infinite value (∞), also so that the circumference of the contact between the two surfaces is close to the elastically deformed middle region 61 of the inner arched annular surface formed in the bottom, in order to form the circumferential radius R2 of the contact.

The operation of a radial hydraulic machine equipped with a preferred oscillating cylinder in the form of the structure described above is performed by the flow of hydraulic liquid from the supply channel 20, 54 to the respective port 18, 40 in and from the cylinder 6, 32, 64 or 66. Due to the effect of the rotation of the crankshaft 1, the cylinder 6, 32, 64 or 66 oscillates through a slight corresponding movement of the hole 18, 40 with respect to the channel 20, 54; the angle of oscillation is therefore limited and the movement between them is largely compensated by the dimensions of the holes and the channels themselves, while in the presence of partial misalignments the flow section of the liquid is very large and close to the section of the channels and the supply holes. On the opposite side, in the presence of pressure, the thrust compensation generated by the pressure inside the cylinder 6, 32, 64 or 66 is provided by the compensation holes 19 or 41 and the respective sealing rings for sliding between the flat and parallel transverse outer sides 17, 39 of the cylinder and the flat lateral sliding surfaces 23, 43. The sealing ring 22 or 45 has a shape that presses the pressure of the liquid against the metal ring, pushing against the flat lateral sliding surface 23 or 42, 43 of the body or cover of said radial hydraulic machine 5, 31 or 62. The size of the compensation holes 41 or recesses 21 corresponds to the size of the supply holes 18, 40 so as to create a slight advantage of the power, maintaining contact against the flat lateral sliding surfaces in correspondence of the supply channels 20, 54 and guaranteeing in each case the sealing of the cylinder and the flat sliding lateral surfaces with the supply channels. In the absence of pressure, the thrust for the sealing contact on the flat sliding side surface is ensured by the elasticity of the sealing ring itself, since it comprises a ring of soft pliable material 51 in the sealing ring 45. Thus, the sealing ring 22, not illustrated and not placed in the cylinder, is placed in the housing 29 of the machine body 10 and in the recess 21 of the cover 11, the sealing ring 22 comprising a ring of soft pliable material, also called "O-ring", an anti-jamming ring of the soft ring and a metal ring, the sealing ring 22 resting on a flat lateral sliding surface from the side on the metal ring, similar to the sealing ring 45.

In the preferred oscillating contact, then, with respect to the technical specifications, between the surfaces contained in the oscillating spherical ring 35 or 65 and the frustoconical inner ring 36 or the inner arched ring 68, the contact itself is completely rigid and rather limited, being a narrow strip around the contact circumference of radius R2, which is therefore in the middle region 61 of the inner frustoconical (trunk-chronic) ring surface 36 or the arch 68, due to the elasticity of the material used. Thus, as normally happens for radial cylinder hydraulic machines, if the dimensions of these surfaces are formed within the parameters described above, even if the variable pressure of the hydraulic liquid is in a high state, working with the contact pressure between the contained materials.

In order to effect contact between the spherical surfaces of oscillation and make use of a spherical toroidal surface having a radius R1 and a diameter D1, if the radius R2 of the circumference of contact between the spherical toroidal surface of radius R1, diameter D1 and the inner frustoconical toroidal surface 36 or the inner arcuate toroidal surface 68 having a curvature R3 is the diameter D and therefore the diameter D, since the surface contained in the portion S where thrust is generated is defined in the region of the annular stripπ(D/2)²Has been deducted at the contact radius R2 and thus pi (R2)²The proposed further solution and the simple spherical contact allow the thrust generated by the liquid under pressure to be limited in its arrangement in the radial oscillating cylinder, avoiding according to the invention the overload of the oscillating contact, by the difference of the circumferential inner area of the direct discharge of the liquid pressure on the body 10 or 33 of the hydraulic machine.

The thrust S to be transmitted between the two surfaces of contact for the oscillation of the cylinder is therefore according to the formula S = Px (pi (D/2)²-π(R2)²) Where P is the instantaneous pressure inside the cylinder during operation.

Therefore, the structure of R2= D/2 results in no thrust effect by the contact of the liquid pressure between the spherical oscillation surface and the contact surface of the base 36 or 68. Thus, the dimensions (measures) of the radius R1 of the spherical surface and the radius R3 of the arched surface or the position and the half-opening angle β of the frustoconical annular surface 36 are such as to allow control of the thrust force S with which contact is made, so as to limit the values within the tolerance limits from the materials used to implement the two contact surfaces.

The presence of thrust means, such as arched wings 25 or rings 48, during operation, enables the oscillating cylinders 6, 32, 57, 64 or 66 to be pushed against the spherical oscillating surface, and also guarantees the oscillating surface during the build-up or in the absence of pressure in the oscillating cylinders: contact and sealing between the spheres 13 and 14; ensuring that the spherical annulus 35 or 65 abuts the frustoconical annulus 36 or the inner arcuate annulus 68.

Finally, the reduction in size allows the oscillating contact of the cylinders to be concentrated inside the circumference of radius R2 and the amplitude of the spherical annular surface of contact between the oscillating cylinder and the body or shell of the hydraulic machine with radial cylinders to be minimized, which allows the passage described in the present invention for the supply or discharge of hydraulic liquid to or from the hydraulic oscillating cylinder to have a larger cross section. This effect is even more pronounced if the feed of the oscillating cylinders is applied on the side of the cylinders themselves, thus limiting the typical radial dimensions of hydraulic machines with oscillating radial cylinders known in the art but as shown in figures 19 and 22, which can be applied even in the case of no feed on the side of the cylinders. .

The advantages in implementation and use of a hydraulic machine with radial cylinders preferred as described above are represented by the simple construction of the surface for carrying out the oscillation of the cylinder block, by applying mechanical elements with cylindrical, spherical or toroidal surfaces as described above. As mentioned above, the need to allow the spherical or toroidal spherical oscillation surface to reposition itself in a lateral position is easily created to compensate for the contact between the external flat lateral surfaces of the cylinder. The cylinder will therefore have only a surface of oscillation on the bottom, and the passage section of the hydraulic fluid, the oscillation movement and the extent of the passage of the liquid are no longer limited, as described in the technical description, by the fixing elements that fix it to the casing, also known in the art; in fact, the section of the passage between the fixed part, the body of the hydraulic machine and the moving cylinder or shell and cylinder as it oscillates is made by the invention in the area of the flat lateral outer surface of the cylinder with less movement by oscillation, as usually happens with oscillating cylinders with trunnions, but it has great advantages compared to oscillating cylinders with trunnions, since the size limitation of the supply channel inside the trunnions is eliminated. Furthermore, the oscillation of the cylinder-piston group occurs on the surface in an axial position compared to the cylinders themselves, on the diametral plane of the cylinder-piston group forming the star arrangement of the hydraulic machine, so as not to undergo drastic changes in the power created by the movement of the crankshaft. Since the examples illustrate the case of different oscillating radial cylinders, both forming the core of the invention, in which the oscillation of the cylinders in a limited area of contact is limited to the elastic deformation of the materials in contact and/or to the feeding with a large transit (or passage) section of the hydraulic liquid, it is possible to feed the cylinders through a flat lateral surface, in order to avoid the restriction of the section of the channel, port and passage hole of the hydraulic liquid from the distributor to the cylinders; the construction of the dispenser can moreover be of any type known in the technical specifications of hydraulic machines, as highlighted in the implementations in which the rotating disc dispenser can be found, but at the same time not present in the first version of the dispenser, which is a multifunctional implementation of the invention.

Furthermore, the constructive form describes a hydraulic motor kit of fixed capacity, but the features and advantages of the present invention can be applied to hydraulic pumps with oscillating radial cylinders, and considering the known techniques of creating flow rate variations in these hydraulic machines, motors and pumps, as well as constant variations in flow rate, in order to predict the oscillating surface, in the case of implementing radial hydraulic motors with variable flow rate, they are limited in terms of performance by the reduction of the flow rate, the limited section of the supply liquid and the poor lubrication of the oscillating surface of the cylinder.

In this way, with the supply on the side of the oscillating cylinder, it is possible to avoid any pressure variations being discharged into the spherical oscillating contact, thus increasing the thrust sharply at low oscillation angles of the hydraulic machine at high pressure and with minimum capacity, since the liquid flow occurs perpendicular to the oscillation level of the cylinder, so that no thrust to the oscillating spherical surface itself is generated, even if it is reduced to the sole elastic yielding of the material around the circumference of the contact.

Furthermore, the oscillating contact between the spherical oscillating surface on the body or shell and the annular surface of the bottom of the cylinder is measured; to such an extent as to allow limited contact with only elastic yielding, which, depending on the speed and pressure of the hydraulic liquid in the machine, allows easy control under all operating conditions, thus allowing the oscillating surface, described as having a large duration and limited friction, to form the oscillation of the cylinder in question.

Finally, if applied to known hydraulic machines, the most clear advantages can be formed with the reduction in size and the increase in the section through which the hydraulic liquid passes in the channels and the feed holes, and therefore with the oscillating cylinders fed from inside the spherical oscillation surface, but with the combination of the invention as described above in hydraulic machines, and with the spherical oscillation surface 35 or 65 of the cylinder being constrained to a narrow strip in contact with the corresponding frustoconical annular surface 36 or arched inner surface 68 with greater curvature, and also with the feeding of hydraulic liquid on the side of the radial oscillation cylinder as described above, further and more important advantages can be achieved.

Obviously, as mentioned above, with an ideal radial hydraulic machine, several modifications can be carried out by the technician from this branch aimed at meeting specific and incidental requirements, all of which are therefore within the field of protection of the present invention as defined by the claims. Even if less advantageous, the sealing ring 22 or 45, described as a composite material, can be made of a combination of one single piece of part or of two parts, obviously these parts having the same features of three components: a ring made of soft pliable material in contact with the housing, an anti-pinch ring to avoid fluid pressure from damaging the soft ring and a metal ring in sliding contact on a flat lateral surface looking down on the housing. Furthermore, it is obvious that the metal surface of the ring in sliding contact is resistant to wear, but it can be replaced, currently at high cost, with a ceramic polish or other material with similar wear-resistant characteristics supporting the contact of the sealing ring with the lateral sliding surface. Furthermore, in a simplified implementation of the invention, for small-capacity applications, compensation of the transverse thrust of the liquid under pressure in the oscillating radial cylinders can be obtained mechanically, since the liquid rests between the flat transverse surfaces of the cylinder block, as opposed to the surfaces through which the liquid is fed, without the chamber or the bearing having a hydrostatic action of compensation.

Finally, instead of the illustrated ring 48 with the arched step 46, it is also possible to use thrust means in the form of a radial hydraulic machine, which can work in the intended manner, thus pushing the cylinder against the seat and the oscillating spherical or toroidal spherical surface in order to react compared with the rest of the thrust means.

Further, the shape of the thrust ring 48 with the arcuate steps 46 may be different than that illustrated, but work in the same manner to propel the respective cylinder against the seat and the oscillating spherical or toroidal spherical surface, as illustrated for the ring 48, with reaction on the other cylinders and their stationary associated parts. In this way, the thrust means consisting of arched wings 25 inside the arched housing on each cylinder 6 or 64 can be made with arched inserts like wings not illustrated and introduced in the arched housing in the same way as the arched housing 26, but on the cylinder and on the flat transverse surfaces (not illustrated) in contact with the sides of the body and of the cover of the machine, so as to form different constructive shapes with similar properties to maintain the contact of the oscillating spherical or toroidal spherical surfaces of the cylinder as described above.

Claims (15)

1. A radial cylinder hydraulic machine comprising: a swinging radial cylinder close to the outer shell of the crown or star cylinder-piston group; the pistons (3) of the group are made to slide on a crankshaft (1) with a crank throw (2) or eccentric, or on interposed elements concentric to the crankshaft (1), and produce an alternating motion inside oscillating radial cylinders; characterized in that it is represented that the oscillating cylinder (32, 57, 64, 66) is placed in contact with a spherical oscillating surface (35, 65) formed or contained in the body (10, 33) or casing of the hydraulic machine; each oscillating radial cylinder is provided with an inner annular surface (36, 68); for coupling with the spherical oscillation surface to make contact with a circumference having a width due to the only elastic yielding of the material in the middle zone (61) of the contact circumference, the radius of the spherical oscillation surface having a greater curvature; furthermore, the radius (R2) of the contact circumference is smaller than half the diameter (D) of the cylinder inner diameter (32, 57, 64, 66); finally, thrust means are included to bring the oscillating cylinder against the oscillating spherical surface on the outside of the same cylinder.

2. A hydraulic machine, according to claim 1, in which the diameter (D1) of the spherical oscillation surface (35, 65) is smaller than the diameter (D) of the internal diameter of the oscillating radial cylinder (32, 57, 64, 66).

3. A hydraulic machine, according to any one of claims 1 or 2, in which the spherical oscillation surface (35, 65) has a defined annular conformation close to a median zone of contact (61) around the circumference of contact with the internal annular surface (36, 68).

4. A hydraulic machine, according to any one of claims 1 or 2, in which the spherical oscillation surface (35) has a defined annular configuration close to a median area of contact (61) around the circumference of contact with the internal annular surface consisting of an internal frustoconical surface (36), and the internal frustoconical surface (36) likewise has a defined annular configuration close to the median area of contact (61) with the spherical oscillation surface.

5. A hydraulic machine, according to any one of claims 1 or 2, in which both the spherical oscillation surface (65) and the internal annular arched surface (68) have an annular conformation defined by a narrow median zone (61) of contact around the circumference of contact between the oscillation surfaces of the hydraulic radial cylinders; the radius of curvature (R3) of the inner arcuate annular surface is greater than a radius of curvature (R1) of the spherical surface of oscillation and less than an infinite value (∞).

6. A hydraulic machine, according to one of the preceding claims 1 to 5, in which the feeding and/or the discharge of hydraulic liquid in the oscillating cylinder is carried out by the side of the cylinder itself.

7. A hydraulic machine with radial cylinders according to claim 6, in which the hydraulic liquid flows to and from the oscillating radial cylinders (32, 64, 66) to form the feeding and discharge of the cylinders to and from the feeding channels (20, 54) on the body (10) or cover (44) of the hydraulic machine (31, 62) by means of at least one external transverse flat surface (16, 38) on the side of the oscillating cylinder parallel to the oscillation plane of the cylinder; -a sealing ring (22, 45) equipped with at least a contact surface resistant to wear on the wall of the flat lateral sliding surface (23, 43), said sealing ring being interposed between said lateral surfaces (16-23, 38-43) in contact for the passage of said liquid under pressure.

8. A hydraulic machine (31, 62) according to claim 7 in which a flat transverse outer surface (17, 39) is parallel and opposite to the flat transverse outer surface (16, 38) of the oscillating cylinder (32, 64, 66), the liquid being fed through the oscillating cylinder (32, 64, 66), a compensation hole (19, 41) with thrust being fed by the liquid under pressure in the oscillating cylinder, the sealing ring (22, 45) surrounding the compensation hole being fitted with at least a contact surface resistant to wear on the wall of the flat lateral sliding surface (23, 42), the sealing ring (22, 45) also being placed between the transverse flat surfaces (17-23, 39-42) in contact for the liquid under pressure to flow through the compensation hole.

9. The hydraulic machine (31, 62) according to claim 8, wherein the surface of the pressure acting in the thrust compensation hole (41) or in the recess (21) formed in the flat lateral sliding surface (23, 42) is slightly greater than the surface of passage under pressure of the liquid in the feed hole (18, 40) in the oscillating radial cylinder (32, 64, 66).

10. Hydraulic machine (31, 62) according to one of claims 7, 8 or 9, in which the sealing rings (22, 45) in sliding contact between the flat transverse outer surface (16, 38) of the oscillating radial cylinder (32, 64, 66) and the transverse flat sliding surface (23, 43) of the cylinder are made up of a combined part in which: a metal ring (53) forming a wear-resistant surface provided on a side face of the sealing ring (22, 45) that is in contact with the sliding surface of the sealing ring; a ring (51) made of a soft pliable material is inserted between the metal ring and the housing (29, 50) or the recess in which the sealing ring (22, 45) is located; an anti-jamming ring (52) is placed between the metal ring (53) and the ring (51) of soft pliable material, so as to avoid the liquid being expelled under pressure during operation.

11. The hydraulic machine (31) according to claim 10, wherein the sealing rings (45) for the feed holes (40) and/or for the thrust compensation holes (41) are placed in their own housing (50) made at the side of the cylinder (32, 66) and in sliding contact with the flat lateral sliding surfaces (42, 43) of the body (33) and of the cover (44) of the radial hydraulic machine (31).

12. Hydraulic machine (31, 62) according to one of the preceding claims 7 to 11, in which the respective oscillation surface of each oscillating radial cylinder of the cylinder-piston group is made by a portion of a spherical surface (35, 65) on a mechanical element (34) close to the outer casing, and the mechanical element (34) is connected with the casing (11, 33) in a manner laterally movable in a direction parallel to the axis of the crankshaft (1), or to a part of the machine or to a side cover.

13. A hydraulic machine (5) with radial cylinders, comprising oscillating radial cylinders (6) close to the outer casing of a crown or star-arranged cylinder-piston group (4); the set of pistons (3) is made to slide on a crankshaft (1) with a crank throw (2) or on a concentric element of a plug and to produce an alternating motion inside the oscillating radial cylinder: the oscillating cylinder (6) is placed in contact with a spherical oscillating surface (13) made on the body or casing of the hydraulic machine; characterized in that the hydraulic liquid flow into and out of the oscillating radial cylinder (6) is present to form the supply and discharge of the cylinder to and from a supply channel (20) on the transverse body (10) or cover (11) of the hydraulic machine (5) by means of a flat transverse outer surface (16) parallel to the oscillation plane of the cylinder at least on the oscillating cylinder side; -a sealing ring (22) equipped with at least a contact surface resistant to wear on the wall of said flat lateral sliding surface (23), said sealing ring being interposed between said flat lateral surfaces (16-23) in contact for the passage of said liquid under pressure; finally, the hydraulic machine comprises thrust means which bring the oscillating cylinder against the spherical oscillating surface on the outside of the cylinder itself.

14. The hydraulic machine (31) according to one of the preceding claims 1 to 13, in which, in order to maintain the contact between the oscillating radial cylinders (32) and the oscillating surfaces (35, 36) of the body (33) or casing of the machine, the thrust means on the cylinders (32, 66) for contact comprise at least one ring (48) fitted with arched contacts (47), the arched contacts (47) coinciding, with respect to the curvature of the portion of the spherical oscillating surface (35, 65) of each cylinder, with respect to the radius of curvature of the oscillating surfaces (35, 65) of the cylinders on the arched element (47) of the thrust means, according to the respective radius of curvature of the arched steps (46) on the respective cylinder (32, 66).

15. Hydraulic machine (5, 62) according to one of the previous claims 1 to 13, in which, in order to maintain the contact between the oscillating radial cylinders (6, 64) and the oscillating surface (13, 14) of the body (10) or casing of the machine, the thrust means on the cylinders for contact on the portion of the oscillating surface comprise arched wings (25) on the sides of the cylinders (6, 64), the arched wings (25) being retained in arched housings (26, 27) according to respective radii or curves of the axes of curvature compared to the portion of the oscillating surface of the cylinder-piston group (4, 63).