Piston compressor

Abstract

A piston compressor (1) has a cylinder (3) with a compartment (7) connected with a supply duct (5) and a delivery duct (6) for the gas and elastically supported so as to be able to oscillate along a longitudinal axis (A); a piston (4) movable with a reciprocating motion (3) so as to compress the gas; an actuator (15) for generating the reciprocating motion of the piston (4) and the cylinder (3) along a longitudinal axis (A); a lubrication duct (17) extending, at least partly, across the cylinder (3) so as to supply lubrication oil into an interstice between the piston (4) and the cylinder (3); and a Tesla valve (16), which is integral with the cylinder (3), is immersed in a lubrication oil bath and has an inlet opening (19) and an outlet opening (20) connected to the lubrication duct (17), and a valvular conduit (18) extending between the inlet opening (19) and the outlet opening (20) in a direction parallel to the given axis (A).

Description

[0001] R. 414491

[0002] - 1 -

[0003] Description

[0004] Title

[0005] Piston compressor

[0006] Technical sector of the invention

[0007] The present invention relates to a piston compressor.

[0008] Prior art

[0009] Piston compressors comprise at least one piston and one cylinder which houses internally the piston which is movable with a reciprocating motion inside the cylinder and is slidably guided by the cylinder.

[0010] The efficiency of the compressor is all the greater the smaller is the play between the piston and the respective cylinder.

[0011] However, the smaller the play the greater will be the wear of the piston and the cylinder and the overheating produced by friction. In order to overcome this drawback it is necessary to inject small amounts of oil into the cylinder in order to reduce, the wear, the friction and the consequent production of heat energy.

[0012] Piston compressors are therefore provided with micropumps for supplying the oil into the interface zone between the piston and the cylinder.

[0013] In general oil micropumps comprise a plunger movable inside a piston so as to generate differences in pressure which allow the oil to be transferred from an inlet opening to an outlet opening. The movement of the plunger of the micropump is ensured by the movement of the part of the compressor to which it is secured. In fact, the micropump uses the oscillations produced by the R. 414491

[0014] - 2 - compressor and the inertia force of the piston which is constrained by springs at its free ends. The quantity of oil supplied is directly proportional to the oscillation frequency. The piston has an internal through-hole inside which a non-return valve is arranged.

[0015] When the pump resonates the relationship between the quantity of oil supplied and the oscillation frequency is however nullified.

[0016] Moreover, the main problems associated with micropumps of the type identified above are as follows:

[0017] - Small amount of oil supplied;

[0018] - Internal movable component;

[0019] - High cost;

[0020] - Resonance frequency to be avoided;

[0021] - Wear of the moving parts.

[0022] Subject-matter and summary of the invention.

[0023] The object of the present invention is to provide a piston compressor which does not have the drawbacks of the prior art.

[0024] In accordance with the present invention a piston compressor is provided, the piston compressor comprising:

[0025] - a cylinder comprising a compartment connected with a supply duct and a delivery duct for the gas and elastically supported so as to be able to oscillate along a longitudinal axis;

[0026] - a piston movable with a reciprocating motion inside the cylinder so as to compress the gas;

[0027] - an actuator for generating a reciprocating motion of the piston and the cylinder along a longitudinal axis;

[0028] - a lubrication duct extending, at least partly, across the cylinder so as to supply lubrication oil into an interstice between the piston and the cylinder; and

[0029] - a Tesla valve integral with the cylinder and immersed in a lubrication oil bath; the said Tesla valve comprising an inlet opening and an outlet opening connected to the lubrication duct, and a valvular conduit extending between the inlet R. 414491

[0030] - 3 - opening and the outlet opening and extending in a direction parallel to the given axis.

[0031] The oscillating movement imparted to the Tesla valve by the cylinder, the orientation of the Tesla valve and the fact that the Tesla valve is immersed in a lubrication oil bath allows the Tesla valve to function in the manner of a pump for supplying the lubrication oil. Generally, the valvular conduit of the valve functions as a non-return valve.

[0032] By subjecting the Tesla valve to a reciprocating motion in the direction parallel to the extension of the valvular conduit it is possible to supply the lubrication oil cyclically when the Tesla valve moves in one direction and prevent the oil supplied from returning into the oil bath when the Tesla valve moves in the opposite direction.

[0033] In particular, the piston comprises a through-hole and a non-return valve inside the through-hole.

[0034] In this way the structure is particularly simple.

[0035] In particular, the piston compressor comprises two springs arranged at the opposite ends of the piston and resting along internal walls of the cylinder.

[0036] In this way it is sufficient to impart a reciprocating motion to the cylinder and, consequently, the piston moves with a reciprocating motion in relation to the cylinder by means of inertia.

[0037] Brief description of the drawings.

[0038] In order to improve the understanding of the present invention an embodiment of the invention is now described, purely by way of a non-limiting example, with reference to the attached drawings, in which Figures 1 and 2 are schematic elevation views of a compressor provided in accordance with the present invention during two respective operating stages. R. 414491

[0039] - 4 -

[0040] Preferred embodiment of the invention.

[0041] With reference to Figures 1 and 2, 1 denotes overall a piston compressor, which comprises a frame 2, a cylinder 3 arranged inside the frame 2, a piston 4 inside the cylinder 3, a supply duct 5 and a delivery duct 6.

[0042] The frame 2 has the form of a tank at least in the bottom part so as to contain a given amount of lubricating oil so as to allow the bottom part of the cylinder 3 to be immersed in the lubricating oil.

[0043] The cylinder 3 extends along a longitudinal axis A, has a compartment 7 and is constrained to the frame 2 by means of springs 8 which allow the cylinder 3 to oscillate in the axial direction with respect to the frame 2, in order to allow the relative movement of the cylinder 3 and the frame 2 and supply the gas into the compartment 7 and expel the gas from the compartment 7. In the case in question, the supply duct 5 and the delivery duct 6 comprise respective flexible portions 9 and 10 for allowing the relative movement of the cylinder 3 and the frame 2.

[0044] The piston 4 extends along the longitudinal axis A and is housed slidably in an axial direction inside the cylinder 3. The piston 4 has a through-hole 11 which extends along the longitudinal axis A and inside which a non-return valve 12 is housed.

[0045] The piston compressor 1 comprises two springs 13 and 14, each of which is arranged inside the compartment 7 between the cylinder and a respective free end of the piston 4.

[0046] The piston compressor 1 comprises an actuator 15 which has the function of imparting a reciprocating motion along the longitudinal axis A to the cylinder 3 and, consequently, to the piston 4 which moves with a reciprocating motion in relation to the cylinder 3.

[0047] In the example shown, the actuator 15 is a motor which actuates a cam. R. 414491

[0048] - 5 -

[0049] According to an alternative embodiment not shown, the motor actuates a connecting rod / crank mechanism.

[0050] In general, the cylinder 3 is supported by guides, not shown in the attached figures, in the axial direction.

[0051] The piston compressor 1 comprises a Tesla valve 16 integral with the cylinder 3 and immersed in the lubrication oil and a duct 17 which connects the Tesla valve 16 to an interstice between the piston 4 and the cylinder 3. The Tesla valve 16 comprises a valvular conduit 18 which extends between an inlet opening 19 and an outlet opening 20 in fluid communication with the duct 17.

[0052] In accordance with a variant not shown in the attached figures, the duct 17 is branched so as to supply the lubricating oil in different zones of the interstice.

[0053] A further non-return valve 21 is provided along the delivery duct 6 in order to prevent the backflow of the compressed gas.

[0054] During use, the actuator 15 imparts an oscillation to the cylinder 3 along the longitudinal axis A.

[0055] With reference to Figure 1 , when the cylinder 3 moves in the direction indicated by the arrow F1 , the piston 4 moves with a relative movement in the direction indicated by the arrow F2 in relation to the cylinder 3 and compresses the gas towards the delivery duct 6. The Tesla valve 16 moves integrally with the cylinder 3 and, during this stage, the valvular conduit 18 has passing through it an oil flow which is supplied to the interstice via the duct 17.

[0056] With reference to Figure 2, when the cylinder 3 moves in the direction indicated by the arrow F1 , the piston 4 moves with a relative movement in the direction indicated by the arrow F2 in relation to the cylinder 3 and transfers the gas through the through-hole 11 and the non-return valve 12 from an intake zone into a zone for compressing the gas. The Tesla valve 16 during this stage, owing to the configuration of the valvular conduit 18, prevents the flow of oil from the outlet opening 20 to the inlet opening 19. R. 414491

[0057] - 6 -

[0058] The rapid succession of oscillations causes an oil flow from the inlet opening 19 to the outlet opening 20 and the supply of lubrication oil to the interstice.

[0059] Finally, it is clear that the embodiment described and illustrated here may be subject to modifications and variations without thereby departing from the scope of protection of the present invention, as defined in the attached claims.

[0060] In particular, according to a variant not shown, the piston compressor comprises a plurality of Tesla valves and associated ducts for supplying the lubrication oil to the interstice.

Claims

R. 414491- 7 -Claims1 . A piston compressor, the compressor (1) comprising:- a cylinder (3) comprising a compartment (7) connected with a supply duct (5) and a delivery duct (6) for the gas and elastically supported so as to be able to oscillate along a longitudinal axis (A);- a piston (4) movable with a reciprocating motion inside the cylinder (3) so as to compress the gas;- an actuator (15) for generating a reciprocating motion of the piston (4) and the cylinder (3) along a longitudinal axis (A);- a lubrification duct (17) extending, at least partly, across the cylinder (3) so as to supply lubrification oil into an interstice between the piston (4) and the cylinder (3); and- a Tesla valve (16) integral with the cylinder (3) and immersed in a lubrification oil bath; the said Tesla valve (16) comprising an inlet opening (19) and an outlet opening (20) connected to the lubrification duct (17), and a valvular conduit (18) extending between the inlet opening (19) and the outlet opening (20) and extending in a direction parallel to the given axis (A).

2. The piston compressor according to Claim 1 , wherein the piston (4) comprises a through-hole (11) and a non-return valve (12) inside the through- hole (11).

3. The piston compressor according to Claim 1 or 2, comprising two springs (13, 14) arranged at the opposite ends of the piston (4) and resting along the internal walls of the cylinder (3).

Images