EP0613527A1

EP0613527A1 - Piston machine for use as a compressor or motor.

Info

Publication number: EP0613527A1
Application number: EP93901789A
Authority: EP
Inventors: Claude Trapp
Original assignee: Seref
Current assignee: Seref
Priority date: 1991-11-22
Filing date: 1992-11-20
Publication date: 1994-09-07
Anticipated expiration: 2012-11-20
Also published as: FR2684140B1; DE69209848T2; EP0613527B1; FR2684140A1; WO1993010353A1; US5479846A; DE69209848D1

Abstract

Le compresseur comporte un carter cylindrique (1) dans l'alésage duquel se déplace un piston (3) dont la périphérie est ajustée à très faible jeu dans le cylindre (1). L'extrémité (5) du piston (3) comporte une entrée de gaz (6) et supporte deux articulations à rotule (7) se poursuivant par des bielles (8, 8') symétriques par rapport à l'axe du piston (3). Les bielles (8, 8') traversent avec jeu une paroi transversale (11) du carter (1) et sont entraînées par un organe mécanique (13), qui comporte une pièce mobile (14) à mouvement rectiligne alternatif, et par l'intermédiaire d'un palonnier (15) d'équilibrage. Les bielles (8, 8') sont reliées au palonnier (15) par des rotules (16, 16'), et le palonnier (15) est relié par une rotule (17) à la pièce mobile (14). L'invention s'applique à la réalisation de machines à couple piston-cylindre, dans lesquelles le piston est entraîné en mouvement relatif alternatif sans transmission d'effort radial.The compressor comprises a cylindrical casing (1) in the bore of which a piston (3) moves, the periphery of which is adjusted with very low clearance in the cylinder (1). The end (5) of the piston (3) has a gas inlet (6) and supports two ball joints (7) continuing by connecting rods (8, 8 ') symmetrical with respect to the axis of the piston (3 ). The connecting rods (8, 8 ') pass through a transverse wall (11) of the housing (1) with play and are driven by a mechanical member (13), which comprises a movable part (14) with reciprocating rectilinear motion, and by the intermediary of a balancing beam (15). The connecting rods (8, 8 ') are connected to the lifter (15) by ball joints (16, 16'), and the lifter (15) is connected by a ball (17) to the moving part (14). The invention applies to the production of machines with a piston-cylinder couple, in which the piston is driven in reciprocating relative movement without transmission of radial force.

Description

Piston machine usable in compressor or engine.

The invention is in the field of machines with piston-cylinder pairs intended to carry out an energy exchange between a pressurized fluid and a mechanical member, and more particularly with a view to producing an air compressor or any other gas, without however excluding the realization of a motor powered by the energy of a generally gaseous fluid.

Machines with pistons connected to mechanical energy organs most often use the classic rod-crank system or sometimes a plate which oscillates around an oblique crank in rotation around an axis parallel to the piston-cylinder couple. There are also known sliding or cam systems. All these systems introduce transverse forces, that is to say radial forces on the pistons relative to their axis, which is a friction factor with wear and creation of dust. A rectilinear guide cancels the transverse forces between piston and cylinder, but it requires lubrication which is a source of pollution, and it makes the whole heavy and bulky.

It is also known to cancel the obliquity of a connecting rod relative to the piston, as well as the corresponding forces, by the use of a cylinder. -Z oscillating. This however creates transverse inertia forces due to its oscillation, which are the source of the same drawbacks as mentioned above.

The object of the invention is to avoid any systematic friction between cylinder and piston, to minimize the wear of these elements and allow their operation for a long period, in particular for non-lubricated machines and without seal between piston. and cylinder therefore without pollution by oil or particles from the wear of these elements.

This embodiment for example for gas compression, even at very high pressures, is allowed by a very precise adjustment of the surfaces facing the cylinder and piston, and over a significant length of the opposite between these two elements.

For example, with a radial clearance of 1 μm and a useful piston length of 40 mm, it is possible to reduce the leakage of a gas along this clearance to a value of less than 10% of the pumped flow rate.

To produce a piston machine offering these advantages, it is necessary to obtain a movement of the piston in the cylinder which is rectilinear within the limits of this very small clearance, and this without systematic radial force. It is therefore necessary to connect the piston to a mechanical member which comprises a moving part animated by the same reciprocating rectilinear movement, part itself linked to the piston or else to the cylinder if it is the latter which is mobile. Indeed, any oblique connection such as a connecting rod linked to a crank creates under the force of the piston a reaction with a radial component thereon.

Various mechanical systems are known where a part is driven by a rectilinear or quasi-rectilinear reciprocating movement. One of the oldest is the connecting rod assembly of

WATT, an example of which is shown in Figures 3 and 4 described below.

Another known system is a so-called gear de LA HIRE, consisting of a fixed crown internally toothed with a half size satellite pinion and a point on the pitch diameter of which describes a straight line which passes through the center of the crown. To drive an elongated piston and with very little play relative to a cylinder it is therefore possible to connect one or the other of these two elements to a part driven by a movement which is rectilinear within the limits of this play. But if the connection is rigid, it is necessary either to align the mechanical member with a better positioning tolerance than the piston-cylinder clearance, which is in practice impracticable when this clearance is a few μm, especially as the expansions and the deformations in operation aggravate the problem, that is to leave to the mechanical member a freedom of transverse positioning, but then its mass is added to that of the driven element, from where radial forces due to gravity or vibrations , which creates friction between piston and cylinder.

To solve this problem, the invention frees, within alignment and transverse mechanical positioning limits of medium precision, the element driven with the rectilinear movement part carried by the mechanical member. We can set the transverse positioning limits to a few l / 10th of mm, and therefore allow a transverse clearance of the same value between the driven element and the part of the mechanical member to which it is connected, without the radial component of the efforts of the movable element become troublesome.

The invention is thus characterized firstly by the use of a ball joint or an equivalent joint having two degrees of angular freedom between one of the elements of a piston-cylinder couple and the part with rectilinear movement of a mechanical organ to which it is connected. This job allows the alignment of this organ with the co Huple piston-cylinder without creating oblique force on the element connected to it. Instead of a ball joint, a Cardan joint can be used, for example, with two crossed axes. Preferably, such an articulation is used simultaneously with each of the two elements of the couple, one with the part with rectilinear movement, the other with an ixed part of the machine.

Secondly the invention is also characterized either by a connecting rod interposed between the aforementioned articulation and the piece with rectilinear movement, or by an articulation which comprises two degrees of freedom in the direction of a movement perpendicular to the movement, it is to say in the transverse direction to the efforts. These transverse movements can be ensured by a flat base of the joint, which rests on a transverse plate provided on the corresponding element, or else by balls interposed between cooperating linear guide surfaces and perpendicular to the reciprocating movement. The transverse displacements are advantageously limited to a value slightly greater than the precision of the positioning of the mechanical member.

The use of ball joints used according to the invention makes it possible to have inside a large diameter piston a blind cylindrical conduit, that is to say closed at one end, of small diameter, parallel to the piston and which constitutes the cylinder of a second couple with variable volume, with a circuit for transferring the fluid under pressure to this second couple. The piston of this second couple is then connected to the cylinder head of the first couple by a ball joint or an equivalent device, which allows an achievable tolerance of the parallelism of the elements and the alignment of their axes.

To make the machine according to the invention clearly understood, there will be described below, by way of examples without limiting character. two forms of execution preferred with reference to the appended schematic drawing in which: FIG. 1 is a schematic perspective view, with cutout and cutaway, of a compressor applying the invention; Figure 2 is a partial sectional view showing a ball joint with two degrees of angular freedom and two degrees of transverse freedom used in the compressor of Figure 1; Figure 3 is a plan view of another piston machine according to the invention; and Figure 4 is a section along line IV-IV of Figure 3.

The compressor shown diagrammatically in FIG. 1 comprises a cylindrical casing 1 sealingly bearing a cylinder head 2. The bore of the casing, which is shown cut in a plane of symmetry, constitutes a first cylinder in which moves a first piston 3 which is itself even bored concentrically to form a second cylinder also carrying with sealing a second cylinder head 4. The peripheries of the cylinder head 4 and most of the piston 3 are adjusted to the same diameter and with very little play in the cylinder 1. The surfaces in with respect to these elements carry surface treatments or materials capable of allowing friction without lubrication.

The end 5 of the piston 3, opposite the second cylinder head 4, has a gas inlet 6, in relation to the interior of the casing 1 and supports two ball joints such as 7.

A cut-out, shown for the first piston 3 and the first cylinder head 4, makes it possible to see the ball joint 7, a connecting rod 8 articulated on the piston 3 by this ball joint and a second connecting rod 8 'symmetrical to the connecting rod 8 relative to the axis piston 3.

Tear it off. - further discovers a second piston 9 which cooperates with? the bore of the first piston 3, to constitute a second compression stage, in the same way as the piston 3 and the bore of the .carter 1 constitute a first compression stage, and with the same adjustments with very small clearance of the surfaces facing these couples d 'elements.

The piston 9 is fixed, being retained by a ball joint 10 articulated in a transverse wall 11 of the casing 1. This wall 11 has two orifices such that

12 to allow sliding with play, therefore without guidance, connecting rods 8 and 8 '. These are driven by means of a mechanical member 13 which comprises a movable part 14 having an alternating rectilinear movement, and by means of a lifting beam 15 for balancing the forces of the connecting rods, the latter being connected to it by ball joints 16 and 16 'symmetrical with respect to the middle of the lifter. The latter is connected by a ball joint 17 to the movable part 14. Thus the piston 3 is driven in reciprocating motion without transmission of radial force therefore with the minimum of friction and wear, in accordance with the object of the invention.

The piston 3 further comprises two identical conduits 18 and 18 'symmetrical with respect to its axis, parallel to the latter and each closed on the side of the end 5. These conduits constitute cylinders respectively receiving pistons 19 and 19' with very low backlash adjustments to form a third compression stage together. The two variable volume couples which they constitute are connected in parallel by a gas intake circuit 20 and by a discharge circuit 21, the latter being drilled in the cylinder head 2. Thus the variable pressures are identical in each of these volumes, which balances the forces on the piston 3. The pistons 19 and 19 'are retained on the fixed cylinder head 2 by ball joints 22 and 22', with two degrees of angular freedom and in addition two degrees of transverse freedom, including one exemplary embodiment is drawn in FIG. 2 and which also equips the piston 9 with its retention on the wall 11 by the ball joint 10. Therefore the pistons 9, 19 and 19 'are aligned in the opposite cylinders only by their respective adjustments, their supports on the fixed parts 11 and 2 taking themselves the position which minimizes the radial forces between pistons and cylinders, even in the case of relatively poor machining resulting in uncertainty about the positions of the ball joints on these fixed parts.

A fourth compression stage also exists inside the piston 9. For this purpose the cylinder head 4 carries on its axis a ball joint similar to the previous three, which retains a fourth piston 23, of small diameter, which cooperates with an adjusted cylinder. which is constituted by a bore of the fixed piston 9 of the second stage. This piston 23 is therefore mobile like the piston 3, and 'driven by it.

The circuits connecting the four compression stages are susceptible of various variants. Here the suction of the first stage is done through the orifice 6 with a conduit inside the piston 3 to supply a suction valve 24 carried by it. The compressed gas is evacuated by a discharge valve 25 then in a circuit passing first through the fixed cylinder head 2, then a heat exchanger 26 and a filter 27, to be introduced into a line 28 of the fixed piston 9 up to a valve suction 29 of the second floor. In the figure, the piston 9 is cut to show this pipe and this valve, as well as the entire length of the mobile piston 23. The discharge of the second stage passes through a valve 30 carried by the mobile cylinder head 4 then a circuit passing through this cylinder head then the piston 3 to join at 31 the circuit 20 for supplying parallel variable volumes of the third stage, with for each of these suction valves 32 and 32 'housed. Inside the piston 3 in the bottoms of the cylinders receiving pistons 19 and 19 '.

The upsets of these variable volumes S pass through these fixed pistons 19 and 19 ', which are drilled over their entire length, preferably with small discharge valves at the end of these and not shown and possibly safety valves 33 and 33' redundant the previous ones at the outlet of the ball joints 22 and 22 ', themselves drilled to communicate with the discharge circuit 21.

Then the gas passes through a heat exchanger 34 and a filter 35, is introduced into the fixed piston 9 and into the variable volume of the fourth stage by a suction valve 36 at the bottom of the bore of this piston. The discharge passes through a contiguous valve 37 and it is evacuated towards use by the pipe 38. An additional heat exchange also exists between the second and the third stages, due to the external mounting of the pipes 20 and 31. Being driven by the movement alternative and in the suction atmosphere of the first floor, they have a good heat exchange with this atmosphere. In addition, they can be fitted with fins and lengthened as required.

In Figure 2 there is shown a diametral section of a ball as used in locations 22 and 22 'of Figure 1. The ball is held between the cylinder head 2 and a retaining piece 70 which is applied against it and retained in this position by means not shown, which may be screws for example. It consists of a stack of parts comprising: - an elastic washer 71 preloaded by the retaining part 70, - a support part 72 having a planar bearing which supports the washer 71 and, on its other face, a spherical bearing, a sphere 73 terminated by a cylindrical part and force fitted, or else with welding or gluing, on the end of the piston 19 and receiving the spherical bearing of the support piece 72, a thrust piece 74 receiving the sphere 73 by a spherical bearing,

- a flat anti-friction washer 75 in contact with a flat face of the thrust piece 74, this washer can however be removed if the bottom

5. of the cylinder head 2 and the thrust piece 74 are compatible in friction.

The bottom of the cylinder head 2, perpendicular to the axis of the piston 19, has a diameter slightly greater than

10 that of the thrust piece 74, so that it can move transversely with two degrees of freedom and thus adjust the axis of the piston 23 with that of the other element of the torque, that is to say conduit 18.

In this example, the various parts are drilled axially to constitute a channel for circulation of the pumped fluid, a channel which can lead to a non-return valve.

In Figures 3 and 4, a

20 machine with a piston 40 which can slide with very little play in a cylinder 41, which is held in a sleeve 42 between a shoulder of this sleeve and a nut 43. A connector 44 carries the suction and discharge valves, not shown, which may be contiguous like those designated at 36 and 37 in Figure 1.

The sheath 42 is suspended in a fixed console 45 by means of a so-called Cardan suspension. This comprises in a known manner a movable ring 46 0 connected to the sheath by two diametrically opposite pins such as 47 and to the console by two other diametrically opposed pins in a perpendicular plane, such as 48. This assembly is equivalent to a ball joint with two angular degrees of freedom for the cylinder 41.

The piston 40 carries a tail 49 enclosed in a clamp 50 with .s clamping screws 51 and 52, the pliers constituting an extension of a rod 53. A ball bearing 54 cooperates without longitudinal play with a hole 55 in the rod 53. This bearing is driven by a Watt connecting rod assembly of a known type, connecting rod assembly constituted here by a connecting rod 56 almost parallel to the longitudinal movement and each of whose ends is carried by a crank 57 or 58. Each of these cranks is articulated by a ball bearing at one of said ends of the connecting rod 56 and by another bearing at an axis fixed 59 or 60, these fixed axes being on either side of the connecting rod 56, so that the offsets of the positions of the mobile ends of the cranks, relative to the axis of the rectilinear movement, compensate each other in the middle of the connecting rod. In this medium, a stud 61 carries the bearing 54, which is thus driven by a very substantially rectilinear longitudinal movement. This movement is in exchange for energy with a mechanical member constituted here by a belt 62 connected to a motor which is not shown and which drives a pulley 63 carrying an eccentric crankpin 64 to actuate the crank 58 in alternating oscillation by means of a connecting rod 65 articulated on the crankpin 64 and on the extension of the crank 58.

The bearing 54 can be mounted without play in the rod 53, which guides the latter precisely in a rectilinear movement compatible with that of the piston 40 in the cylinder 41, even in the event of misalignment due to the mounting of the cardan shaft of the cylinder. 41.

As a variant, the rod 53 can actuate a second piston-cylinder couple by means of a second clamp 66. In this case, a second universal joint assembly supports the second couple and it precisely defines the axis of the reciprocating rectilinear movement of the two pistons. To make it compatible with that of the bearing 54, it is then necessary either to make the hole 55 oblong in the transverse direction, as indicated in FIG. 3. or to give the four trunnions of the ring -6 a possibility of displacement M along their axes, which are perpendicular to the reciprocating rectilinear movement which then gives the cylinder 40 - piston 41 couple two degrees of freedom of movement perpendicular to this movement. It will be understood that the above description has been given by way of example, without limitation, and that additions or constructive modifications could be made without departing from the scope of the invention.

Claims

1. Machine for exchanging energy between on the one hand a mechanical member which comprises a movable part (14, 54) having a reciprocating rectilinear movement and on the other hand a piston cooperating with a cylinder to transfer a fluid under pressure, with a connection of one of them with the moving part and a connection of the other with a fixed part, characterized in that the connection of the piston and that of the cylinder each comprise an articulation with two degrees of angular freedom, such than a ball joint

(7.7 ', 10.22.22', 54.73) or a Cardan joint

(46).

2. Machine according to claim 1, characterized in that at least one of the articulations further comprises two degrees of freedom of movement perpendicular to the rectilinear movement, by means of surfaces perpendicular to this movement and in mutual sliding support.

3. Machine according to claim 1 or claim 2, characterized in that the movable part (14) is part of a gear of LA HIRE.

4. Machine according to claim 1 or claim 2, characterized in that the movable part (54) is part of a connecting rod of WATT.

5. Machine according to any one of claims 1 to 4, with a first piston (3) movable in a fixed casing (1) and comprising a bore which cooperates with a fixed piston (9), characterized in that the first piston (3) is driven by two connecting rods (8,8 ') which are connected to it by two ball joints (7,7') and in that the fixed piston (9) is connected by a ball joint (10) to a wall (11 ) attached to the housing (1).

6. Machine according to claim 5, characterized in that the connecting rods (8, 8 ') are connected by two ball joints (16.16'), via a lifting beam (15), to a movable part (14) having a rectilinear movement. • L3

7. Machine according to claim 5 or claim 6, characterized in that the first piston (3) and the housing (1) constitute a pressurized fluid transfer stage.

8. Machine according to any one of claims 5 to 7, characterized by several identical conduits (18,18 ') in the piston (3), interconnected by circuits (20,21) and each receiving a piston (19 , 19 ') fixed by a ball joint (22,22') connected to a cylinder head (2) carried by the fixed casing (1).

9. Machine according to any one of claims 5 to 8, characterized in that the fixed piston (9) has a bore which cooperates with a mobile piston (23) connected by a ball joint to a cylinder head (4) fixed to the first piston (3).