EP4296511B1

EP4296511B1 - Reciprocating volumetric compressor structure

Info

Publication number: EP4296511B1
Application number: EP23181253.8A
Authority: EP
Inventors: Giampaolo Gentilin; Giuseppe Gentilin
Original assignee: Gentilin Srl
Current assignee: Gentilin Srl
Priority date: 2022-06-24
Filing date: 2023-06-23
Publication date: 2024-12-04
Anticipated expiration: 2043-06-23
Also published as: EP4296511A1

Description

The present invention relates to a reciprocating volumetric compressor structure, which can be used for a variety of applications, such as powering paint guns or compressed-air tools, performing blowing operations in machine shops, and still more.
See CN108252895 A , disclosing a device according to the state of the art.
It is well known that in order to produce the compressed air required to perform operations such as painting industrial products, such as cars or earth-moving machines, reciprocating volumetric compressors are used, which compress air flow rates that vary according to application requirements.
Such reciprocating volumetric compressors generally comprise:

two opposite pistons fixed, coaxially to each other, to a same rigid translating body;
two cylinders, one for each of said pistons;
a connecting rod, hinged to the rigid translating body with first hinge means defining a first rotation axis;
an electric motor with a drive shaft having a second rotation axis;
an eccentric body fixed to said drive shaft and rotatably constrained to the connecting rod with second hinge means defining a third rotation axis;
two heads, each configured and positioned so as to close a corresponding cylinder, each head having suction and delivery one-way valve means;
two suction and compression chambers, each defined within a cylinder, between a corresponding piston and a facing head;
a guide and sliding ring for the piston far away from the first hinge means, and two guide rings for the piston close to the first hinge means, said guide and sliding rings being fixed to the respective piston so as to be in contact with the inner surface of the corresponding cylinder;
a casing, on which said cylinders and said electric motor are fixed, said rigid translating body, said connecting rod and said eccentric body being positioned within said casing.

Such reciprocating volumetric compressors, although well known and appreciated, have aspects that can be refined.
A first aspect to be refined is the fact that the connecting rod, through the first hinge means, acts on the rigid translating body according to directions transverse to the translation axis of the same rigid translating body; this causes the two piston guide and sliding rings near the first hinge means to be heavily stressed in the radial direction, resulting in wear, where such wear causes a progressive lack of tightness between the cylinder and piston and a consequent drop in the performance of the volumetric compressor itself.
A second aspect that can be refined relates to the compressor compactness in the direction of the axis of the movement of the pistons, as even in this technical field a reduction in overall dimensions is always sought, as well as a reduction in the number of components to the benefit of simplicity and speed of assembly thereof.
The task of the present invention is to develop a reciprocating volumetric compressor structure capable of obviating the aforementioned drawbacks and limitations of the prior art.
In particular, an object of the invention is to develop a reciprocating volumetric compressor structure capable of maintaining the same high efficiency for longer than similar compressors of the known type.
Another object of the invention is to develop a reciprocating volumetric compressor structure with an improved pneumatic sealing.
A further object of the invention is to develop a reciprocating volumetric compressor structure more compact than similar volumetric compressors of the known type.
The above-mentioned task and objects are achieved by a reciprocating volumetric compressor structure according to claim 1.
Further characteristics of the reciprocating volumetric compressor structure according to claim 1 are described in the dependent claims.
The aforesaid task and objects, together with the advantages that will be mentioned hereinafter, are indicated by the description of an embodiment of the invention, which is given by way of non-limiting example with reference to the attached drawings, where:

Figure 1 represents a perspective view of a volumetric compressor structure according to the invention;
Figure 2 represents a perspective exploded view of a group of components of the volumetric compressor structure according to the invention;
Figure 2A represents a plan view of a detail of the group of components of Figure 2;
Figure 2B represents a plan view of the assembly of two details of the group of components of Figure 2;
Figure 3 represents a perspective cross section of the volumetric compressor structure according to the invention;
Figure 4 represents a cross-sectional side view of a volumetric compressor structure according to the invention;
Figure 5 represents a sectional plan view of a first portion of the compressor structure according to the invention;
Figure 6 represents a sectional plan view of a second portion of the compressor structure according to the invention;
Figure 7 represents a first perspective view of an exploded view or of another group of components of the compressor structure according to the invention;
Figure 8 represents a second perspective view of the exploded view of Figure 7;
Figure 9 represents a perspective cross section of a portion of the volumetric compressor structure according to the invention;
Figure 10 represents another perspective cross section of the portion of the volumetric compressor structure of Figure 9;
Figure 10A represents a perspective detail of the compressor structure according to the invention;
Figure 10B represents a section view of the detail of Figure 10A;
Figure 11 represents a sectional detail of the volumetric compressor structure according to the invention.

With reference to the mentioned figures, a reciprocating volumetric compressor structure according to the invention is indicated as a whole by number 10. This reciprocating volumetric compressor structure 10 comprises:

two opposite pistons 11 and 12 fixed coaxially to each other to a same rigid translating body 13;
two cylinders 14 and 15, one for each of said pistons 11 and 12;
a connecting rod 16, hinged to the rigid translating body 13 with first hinge means 17 defining a first rotation axis X1;
an electric motor 18 with a drive shaft 19, shown in Figure 4, having a second rotation axis X2;
an eccentric body 20 fixed to said drive shaft 19 and rotatably constrained to said connecting rod 16 with second hinge means 21 defining a third rotation axis X3, also clearly visible in Figure 4; said third rotation axis X3 is, in particular, parallel to the second rotation axis X2 and rotates around such second rotation axis X2;
two heads 22 and 23, each configured and positioned so as to close a corresponding cylinder 14 and 15, each head having suction and delivery one-way valve means 24 and 25;
two suction and compression chambers 26 and 27, each defined within a respective cylinder 14 and 15, between a corresponding piston 11 and 12 and a facing head 22 and 23, as clearly visible in Figures 5 and 6;
at least one guide and sliding ring 31 and 32 for each piston 11 and 12; this at least one guide and sliding ring 31 and 32 is fixed to the respective piston 11 and 12 so as to be in contact with the inner surface of the corresponding cylinder 14 and 15;
a casing 28, on which said cylinders 14 and 15 and the electric motor 18 are fixed; inside the casing 28 the rigid translating body 13, the connecting rod 16 and said eccentric body 20 are positioned.

The peculiarity of the reciprocating volumetric compressor structure 10 according to the invention lies in the fact that at least one of said pistons 11 and 12 comprises at least two guide and sliding rings 32, 32a, preferably three guide and sliding rings 32, 32a, 32b, as clearly shown in Figures 2 to 6.
In particular, such a piston comprising at least two guide and sliding rings 32, 32a is the second piston 12, closer to the first hinge means 17.
In particular, in the embodiment of the invention described herein by way of illustrative and non-limiting example of the invention itself, a first piston 11, further away from the first hinge means 17, comprises a single first guide and sliding ring 31, while a second piston 12, closer to the first hinge means 17, comprises four second guide and sliding rings 32, 32a, 32b, 32c placed side by side.
It is not excluded, however, that in different embodiments of the invention these second guide and sliding rings may be two in number, preferably three or more than four.
Advantageously, according to any embodiment of the invention just described, at least one of said second guide and sliding rings 32, 32a, 32b, 32c is positioned so as to surround said first hinge means 17.
This last characteristic allows the radial forces transmitted from the connecting rod 16 to the piston 12 to be well distributed at least on the second rings 32, 32a, 32b, making the wear of the individual second rings 32, 32a, 32b, 32c much slower and thus leading to an important extension of the operational life of the volumetric compressor structure 10.
At the same time, the presence of the at least two second guide and sliding rings 32, 32a, 32b, of which at least one is positioned so as to surround said first hinge means 17, determines an equally important improvement in the sealing between cylinder 15 and piston 12, resulting in improved overall efficiency of the reciprocating volumetric compressor structure 10.
In particular, such at least one of the second guide and sliding rings 32, 32a, 32b, 32c positioned so as to surround the first hinge means 17 is designed to be mounted so that it is at the point of maximum thrust and return angle during the swinging movement of the hinged connecting rod 16.
The first hinge means 17 comprise, by way of example, a pin 17a, a needle roller bearing 17b and two opposite annular seals 17c, positioned in a corresponding annular seat 16a defined at one end of the connecting rod 16, where the pin 17a is simultaneously arranged with its ends in corresponding holes 13a defined on the rigid translating body 13.
In particular, the second piston 12 comprises a fixing head 34, fixed to the rigid translating body 13, to which a cup-shaped cap 35 is in turn fixed.
This cup-shaped cap 35 comprises a circular base 35a and a cylindrical wall 36.
This cup-shaped cap 35 comprises a cylindrical wall 36 bearing as many annular cavities 37 as there are second guide and sliding rings 32, 32a, 32b, 32c.
In the present embodiment, three second guide and sliding rings 32, 32a and 32b, as clearly visible in Figures 4 and 5, surround, supported by the cup-shaped cap 35, the first hinge means 17.
In the present embodiment, the annular cavities 37 all have the same width in the direction of the axis of the cup-shaped cap 35.
The second guide and sliding rings 32, 32a, 32b, 32c have therefore also the same width.
Thanks to this peculiar configuration, the forces that the connecting rod 16 transmits to the second piston 12, causing the friction of the latter against the inner surface of the corresponding cylinder 15, are better distributed among the four second guide and sliding rings 32, 32a, 32b, 32c if compared to known compressors comprising one or two rings, which rings, in known configurations, are also distant from the first hinge means, i.e. they do not surround the pin between the connecting rod and the rigid translating body. The second guide and sliding rings 32, 32a, 32b and 32c are annular and their axis of symmetry is parallel to a translation direction Z of the rigid translating body 13.
In the present embodiment, the rigid translating body 13 has a symmetrical structure, as clearly visible in Figure 2A.
Such a rigid translating body 13 has a circular central part with a centre C; a plane of transverse symmetry P1 and a plane of longitudinal symmetry P2 pass through this centre C.
The dotted line representing the plane of longitudinal symmetry P2 is the same as that representing the translation direction Z.
A first distance A1 between the centre C and a first end of a first piston 11 is substantially the same as a second distance A2 between the centre C and a second end of the second piston 12, as is well schematised in Figure 2B.
The translation direction Z is, for example, orthogonal to the rotation axis X2 of said drive shaft 19.
In particular, the second guide and sliding rings 32, 32a, 32b and 32c are annular and their axis of symmetry is orthogonal to the first rotation axis X1 of the first hinge means 17.
This peculiar reciprocating volumetric compressor structure 10 allows the radial forces transmitted from the connecting rod 16 to the piston 12 to be well distributed over at least the three first second rings 32, 32a, 32b, making the wear of the individual second rings 32, 32a, 32b, 32c much slower and thus leading to a significant extension of the service life of the volumetric compressor structure 10.
At the same time, the presence of at least three second guide and sliding rings 32, 32a, 32b leads to an equally important improvement in the sealing between cylinder 15 and piston 12, resulting in an improvement in the overall efficiency of the reciprocating volumetric compressor structure 10.
Each of said first 11 and second 12 pistons comprises:

a fixing head 34 and 38 fixed to the rigid translating body 13;
a cover 39 and 40, fixed to the respective fixing head 34 and 38;
a perimetral elastic gasket 41 and 42 having a substantially L-shaped cross-section.

A similar perimetral elastic gasket 42 is well shown in the section of Figure 11; the perimetral elastic gaskets 41 and 42 are to be understood as equal.
The perimetral elastic gasket 41 and 42 comprises:

an annular base portion 41a configured to be pressed between the fixing head 34 and 38 and the respective cover 39 or 40; alternatively, the annular base portion 41a is configured to be pressed between the circular base 35a of the cup-shaped cap 35, and the respective cover 40, as in Figure 11;
and a sealing portion 41b extending perimetrally from said annular base portion 41a.

The sealing portion 41b is configured to be in contact with the inner surface of the corresponding suction and compression chamber 26 and 27.
The sealing portion 41b and said cover 39 and 40 are configured in such a way that a compression gap 45 is defined between them, as visible in Figure 11.
In the compression steps, i.e. during the movement of the first 11 and second 12 piston towards the respective head 22 and 23, this compression gap 45 allows air to interpose itself between the sealing portion 41b and the cover 39 and 40, so as to act pushing against the sealing portion 41b in an outward radial direction; thereby, the sealing portion 41b increases its sealing efficiency against the inner surface of the suction and compression chamber 26 and 27. More in particular, the cover 39 and 40 comprises a pinch relief 40a configured to press the annular base portion 41a against the cover 39 or 40 in a variant embodiment not shown, or against the circular base 35a of the cup-shaped cap 35, as shown in Figure 11.
The pinch relief 40a determines an improved clamping of the annular base portion 41a of the perimetral elastic gasket 41 and 42.
Each of said one-way valve means 24 and 25, which are well represented in Figures 7 to 10, comprises:

an inner plate 51 with at least one first suction opening 52 and at least one first delivery opening 53; in the embodiment shown in Figures 7 and 8, the inner plate 51 comprises three first suction openings 52 and two first delivery openings 53, where each of these openings consists of a through-hole; this inner plate 51 is facing a corresponding suction and compression chamber 26 and 27;
one of said heads 22 and 23; each of said heads 22 and 23 comprises a base portion 22a and 23a facing the corresponding inner plate 51; at least a second suction opening 54 and at least a second delivery opening 55 are defined in the base portion 22a and 23a.

In particular, in this embodiment, two second suction openings 54 are defined in the base portion 22a and 23a, each defined by a through-hole.
Said at least one second delivery opening 55 consists of an opening having a substantially U-shaped profile with a diverter plane 55b tilted towards the inside of the head 22 and 23.
The one-way valve means 24 and 25 also comprise:

a shaped gasket 56; that shaped gasket 56 is positioned interposed between the inner plate 51 and the corresponding head 22 and 23; the shaped gasket 56 comprises a suction window 57, positioned and configured so as to put said first suction openings 52 and said second suction openings 54 in communication, and a delivery window 58, positioned and configured so as to put said first delivery openings 53 and said second delivery opening 55 in communication;
a first shutter foil 60 for the one-way obstruction of said at least one second suction opening 54; said first shutter foil 60 is fixed between the shaped gasket 56 and the base portion 22a and 23a of the respective head 22 and 23 so as to protrude in a cantilevered manner in said suction window 57, as clearly visible in Figures 7 and 8;
a second shutter foil 61 for the one-way obstruction of said at least one first delivery opening 53; said second shutter foil 61 is fixed between said shaped gasket 56 and the inner plate 51 so as to protrude in a cantilevered manner in the delivery window 58.

The first shutter foil 60 consists, for example, of a metal foil shaped to include a fixing portion 60a from which two side-by-side and independent shutter appendages 60b develop.
The second shutter foil 61 consists, for example, of a metal foil shaped to include a fixing portion 61a from which two side-by-side and independent shutter appendages 61b develop.
In each of said heads 22 and 23 they are defined:

a delivery passage 62 configured for connection between a delivery mouth 62a, open to the outside of the volumetric compressor structure, and said at least one second delivery opening 55;
a filtering chamber 63 communicating with at least a second suction opening 54;
at least one suction passage 64 configured to connect a perimetral portion of the base portion 22a and 23a with the filtering chamber 63.

Such at least one suction passage 64 is schematised in hatching in Figure 10 and is clearly represented and visible in Figure 10B; in the embodiment herein shown, the head 22 comprises two suction passages 64, defined by two channels made in the body of the head 22 and communicating with the filtering chamber 63 via a corresponding through opening 64a.
Each of the cylinders 14 and 15 comprises a tubular wall 66 wherein at least one suction channel 67 is defined extending in a direction parallel to a translation direction Z of said pistons 11, 12 in the respective compression chamber.
The suction channels 67 can be, for example, two for each cylinder 14 and 15. The suction channels 67 are in communication with a corresponding suction passage 64 by means of a corresponding first opening 69 defined on said inner plate 51 and an adjacent second opening 70 defined on said shaped gasket 56.
Practically, it has been established that the invention achieves the intended task and objects.
In particular, the invention developed a reciprocating volumetric compressor structure capable of maintaining the same high yield for longer than similar compressors of the known type.
In addition, the invention developed a reciprocating volumetric compressor structure with improved pneumatic sealing.
In addition, the invention developed a reciprocating volumetric compressor structure more compact than similar volumetric compressors of the known type.
The invention thus conceived is susceptible of numerous modifications and variations within the scope of the appended claims.
In practice, the components and materials used, provided they are compatible with the specific use, as well as the contingent shapes and dimensions, may be any according to the requirements and the state of the art.
Where the characteristics and techniques mentioned in any claim are followed by reference notes, such reference notes should be intended as having been added for the sole purpose of increasing the intelligibility of the claims and, consequently, such reference notes have no limiting effect on the interpretation of each element identified by way of example by such reference notes.

Claims

Reciprocating volumetric compressor structure (10) comprising:
- two opposite pistons (11, 12) fixed coaxially to each other to a same rigid translating body (13);

- two cylinders (14, 15), one for each of said pistons (11, 12);

- a connecting rod (16), hinged to said rigid translating body (13) with first hinge means (17) defining a first rotation axis (X1);

- an electric motor (18) with a drive shaft (19) having a second rotation axis (X2);

- an eccentric body (20) fixed to said drive shaft (19) and rotatably constrained to said connecting rod (16) with second hinge means (21) defining a third rotation axis (X3);

- two heads (22, 23), each configured and positioned to close a corresponding cylinder (14, 15), each head (22, 23) having suction and delivery one-way valve means (24, 25);

- two suction and compression chambers (26, 27), each defined within a cylinder (14, 15), between a corresponding piston (11, 12) and a facing head (22, 23);

- at least one guide and sliding ring (31, 32) for each piston (11, 12), said at least one guide and sliding ring (31, 32) being fixed to the respective piston (11, 12) so as to be in contact with the inner surface of the corresponding cylinder (14, 15);

- a casing (28), on which said cylinders (14, 15) and said electric motor (18) are fixed, said rigid translating body (13), said connecting rod (16) and said eccentric body (20) being positioned within said casing (28),
wherein a first piston (11), further away from the first hinge means (17), comprises at least one first guide and sliding ring (31), and a second piston (12), closer to the first hinge means (17), comprises at least two second guide and sliding rings (32, 32a, 32b, 32c) placed side by side, preferably three second guide and sliding rings (32, 32a, 32b, 32c), placed side by side, characterised in that at least one of said second guide and sliding rings (32, 32a, 32b) is positioned so as to surround said first hinge means (17).
Reciprocating volumetric compressor structure according to claim 1, characterised in that said second piston (12), which is closer to the first hinge means (17), comprises four second drive and sliding rings (32, 32a, 32b, 32c) placed side by side.
Reciprocating volumetric compressor structure according to one or more of the preceding claims, characterised in that said second piston (12) comprises a fixing head (34), fixed to said rigid translating body (13), to which a cup-shaped cap (35) is fixed, said cup-shaped cap (35) comprising a cylindrical wall (36) bearing as many annular cavities (37) as there are second guide and sliding rings (32, 32a, 32b, 32c).
Reciprocating volumetric compressor structure according to one or more of the preceding claims, characterised in that each of said first (11) and second (12) pistons comprises:
- a fixing head (34, 38) fixed to said rigid translating body (13);

- a cover (39, 40), attached to said fixing head (34, 38);

- a perimetral elastic gasket (41, 42) with a substantially L-shaped cross-section.
Reciprocating volumetric compressor structure according to the preceding claim, characterised in that said perimetral elastic gasket (41, 42) comprises:
- an annular base portion (41a) configured to be pressed between said fixing head (34, 38) and said cover (39, 40),

- and a sealing portion (41b) extending perimetrally from said annular base portion (41a),
said sealing portion (41b) being configured so as to be in contact with the inner surface of the corresponding suction and compression chamber (26, 27), said sealing portion (41b) and said cover (39, 40) being configured so that a compression gap (45) is defined between them.
Reciprocating volumetric compressor structure according to one or more of the preceding claims, characterised in that each of said one-way valve means (24, 25) comprises:
- an inner plate (51) with at least one first suction opening (52) and at least one first delivery opening (53), said inner plate (51) being facing one said corresponding suction and compression chamber (26, 27);

- one of said heads (22, 23), each of said heads (22, 23) comprising a base portion (22a, 23a) facing said inner plate (51), in said base portion (22a, 23a) being defined at least a second suction opening (54) and at least a second delivery opening (55);

- a shaped gasket (56), said shaped gasket being positioned as interposed between said inner plate (51) and said head (22, 23), said shaped gasket (56) comprising a suction window (57), positioned and configured so as to put in communication said first suction opening (52) and said second suction opening (54), and a delivery window (58), positioned and configured so as to put in communication said first delivery opening (53) and said second delivery opening (55);

- a first shutter foil (60) for the one-way obstruction of said at least a second suction opening (54), said first shutter foil (60) being fixed between said shaped gasket (56) and said base portion (22a, 23a) of said head (22, 23) so as to protrude, in a cantilevered manner, in said suction window (57);

- a second shutter foil (61) for the one-way obstruction of said at least one first delivery opening (53), said second shutter foil (61) being fixed between said shaped gasket (56) and said inner plate (51) so as to protrude, in a cantilevered manner, in said delivery window (58).
Reciprocating volumetric compressor structure according to the preceding claim, characterised in that in each of said heads (22, 23) they are defined:
- a delivery passage (62) configured for connection between a delivery mouth, open to the outside of the volumetric compressor structure, and said at least one second delivery opening (55);

- a filtering chamber (63) communicating with said at least a second suction opening (54);

- at least one suction passage (64) configured to connect a perimetral portion of said base portion (22a, 23a) with said filtering chamber (63).
Reciprocating volumetric compressor structure according to one or more of the preceding claims, characterised in that each of said cylinders (14, 15) comprises a tubular wall (66) wherein at least one suction channel (67) is defined developing in a direction parallel to a translation direction (Z) of said pistons (11, 12) in the respective compression chamber, said at least one suction channel (67) being in communication with one of said suction passages (64) by means of a corresponding first opening (69) defined on said inner plate (51) and an adjacent second opening (70) defined on said shaped gasket (56).
Reciprocating volumetric compressor structure according to one or more of the preceding claims, characterised in that said translation direction (Z) is orthogonal to the rotation axis (X2) of said drive shaft (19).