Oil-free circular piston compressor

Abstract

The invention relates to an oil-free positive displacement piston compressor (1) comprising: a suction disc (2) with suction pistons (3), each having an inlet and an outlet with a non-return valve (4) and being supplied with gas by a supply circuit; a compression disc (6) with compression pistons (7), also provided with a non-return valve (8), and connected to a compressed gas discharge circuit; a rotary drive shaft (10) driven by a motor; and a wheel (12) with chambers (13) for the suction (7) and compression (8) pistons, which is coaxial with the shaft (10). The suction disc (2) and the compression disc (6) are inclined with respect to the axis of the shaft.

Description

Oil-free circular piston compressor

[0001] The invention relates to the field of oil-free positive displacement compressors, particularly piston compressors, used especially in braking systems and related applications requiring efficient fluid compression. This type of compressor is notably used in the railway sector. Technological background

[0002] Patent document number EP0839280 discloses a piston compressor for compressing gas. This compressor comprises a frame with at least one cylinder having a substantially horizontal axis. A reciprocating piston is present in the cylinder. A piston rod is attached to one end of the piston. The other end of the rod is coupled to a piston arm. This arm is guided within the frame and moved reciprocatingly by a drive mechanism. There are support means for the piston / piston rod unit relative to the frame. This unit is formed by the piston and the rod connected to it. The support means include a source that continuously delivers a pressurized gas. A conduit is connected to this source and opens to at least one exhaust port. This port supplies the gas from the source to a point located between the piston and the cylinder.The location of this opening and the gas pressure are designed so that the gas exerts a constant upward pressure on the piston / piston rod unit.

[0003] This approach has limitations.

[0004] The initial technical problem lies in the efficiency and reliability of positive displacement piston compressors, which are essential for the optimal operation of servo and braking systems, for example, in trains. Current compressors often suffer from performance losses due to air leaks, premature wear of seals, and inefficient gas flow management, as well as significant compressor vibrations, which can lead to reduced compression power and increased maintenance costs. If these problems are not resolved, it can result in frequent breakdowns, reduced operational safety, particularly in railways, and increased operating costs for railway companies.Current state-of-the-art technology has attempted to address these issues by improving the design of oil-free pistons, as well as using stronger materials for seals.

[0005] However, these solutions proved insufficient, as they failed to guarantee optimal sealing under varying operating conditions, nor to maximize the efficiency of gas transfer between the different chambers of the compressor.

[0006] Therefore, it is necessary to develop a positive displacement piston compressor that incorporates innovations in design with simpler kinematics by avoiding parts that transform reciprocating motion into rotary motion, as well as in the configuration of pistons and chambers, in order to improve sealing, optimize gas flow and reduce component wear, while ensuring reliable and durable performance under demanding operating conditions.

[0007] According to one embodiment, the invention provides an oil-free positive displacement piston compressor comprising: - a suction disc comprising a plurality of suction pistons, each suction piston comprising an inlet and an outlet equipped with a suction check valve, the suction disc having an internal surface and an external surface opposite the internal surface, the suction pistons being located on a periphery of the internal surface, the suction disc comprising a gas supply circuit configured to supply gas to the inlet of the suction pistons, - a compression disc comprising a plurality of compression pistons, each compression piston comprising an inlet equipped with a compression check valve and an outlet, the compression disc having an internal surface and an external surface opposite the internal surface, the compression pistons being located on a periphery of the internal surface.the compression disc comprising a compressed gas evacuation circuit connected to the outlet of the compression pistons and configured to evacuate the compressed gas when the compression check valves are opened, - a rotating drive shaft extending along a shaft axis, the drive shaft being intended to be driven by a motor, - a wheel comprising a plurality of chambers passing through the wheel and located on a peripheral periphery of the wheel, each chamber having a shape complementary to one of the suction pistons and one of the compression pistons, each chamber housing at least partially one of the suction pistons and one of the compression pistons, the wheel having a wheel axis of revolution coaxial with the shaft axis, the wheel being rotationally fixed to the drive shaft, in which the suction disc has a first axis of revolution inclined at a first angle of inclination with the shaft axis,and the compression disc has a second axis of revolution inclined at a second angle of inclination with the shaft axis.

[0008] Thanks to these features, the inclined configuration of the suction and compression discs relative to the wheel allows compression cycles to be performed simply by rotating the wheel, which is driven by the drive shaft. The specific shape of the chambers and pistons optimizes the compressed volume per cycle.

[0009] This compressor offers the advantage of reduced energy demand and simplified transformation from reciprocating piston motion to rotating disc motion, thanks to the innovative design of the chambers, pistons and discs, allowing for more efficient use of the energy supplied by the engine.

[0010] According to embodiments, such a compressor may include one or more of the following characteristics.

[0011] According to one embodiment, the first angle of inclination is between 1 degree and 20 degrees, and the second angle of inclination is between -1 degree and -20 degrees.

[0012] According to one embodiment, the first angle of inclination is opposite to the second angle of inclination.

[0013] The opposing angles of inclination between the suction and compression discs can balance the lateral forces generated during operation, which reduces vibration and noise, thus improving, for example, the comfort of passengers and railway staff.

[0014] According to one embodiment, at least one, several or each suction piston includes a sealing gasket having a sealing lip in contact with the chamber housing said suction piston, all around said suction piston, and in which at least one, several or each compression piston includes a sealing gasket having a sealing lip in contact with the chamber housing said compression piston, all around said compression piston.

[0015] The use of seals with sealing lips in contact all around the pistons ensures superior sealing, compensates for the variable spaces between the pistons and the wheel that exist between the compression chambers and the pistons, which prevents gas leaks and improves the overall efficiency of the compressor.

[0016] The presence of sealing rings on each piston eliminates the need for lubricating oil and reduces the risk of cross-contamination between the intake air and the lubricating oil, thus ensuring the purity of the compressed gas for sensitive applications.

[0017] According to one embodiment, the sealing joint is made of composite material comprising PTFE.

[0018] The use of composite material including PTFE for sealing gaskets offers excellent chemical and thermal resistance, which is particularly advantageous in railway environments where temperatures and operating conditions can vary considerably.

[0019] This composite material containing PTFE has a low coefficient of friction, which reduces wear on seals and pistons, thus extending the life of the compressor and decreasing the frequency of parts replacements.

[0020] Composite seals containing PTFE are also known for their ability to maintain effective sealing over a wide pressure range, which is essential for maintaining compressor performance in applications such as railways where pressure demands can vary rapidly.

[0021] According to one embodiment, at least one, several, or each chamber has a cylindrical shape with an oblong base whose generatrices extend parallel to the wheel axis, the oblong base extending along an angular sector of the wheel, the plurality of chambers being distributed regularly around the peripheral perimeter.

[0022] The cylindrical design with an oblong base of the chambers allows for optimization of space within the wheel, which can lead to an increase in the volumetric efficiency of the compressor and an extremely advantageous Weight / Volume ratio.

[0023] The regular distribution of chambers around the peripheral perimeter ensures dynamic balancing of the wheel, thus reducing vibrations and wear of mechanical components.

[0024] According to one embodiment, at least one, several or each suction piston and / or at least one, several or each compression piston have a frustoconical shape with oblong bases, the oblong bases having a proximal base fixed respectively to the inner surface of the suction disc or the compression disc and a distal base located in one of the chambers, the distal base having a surface greater than the proximal base.

[0025] The truncated conical shape of the suction and compression pistons with oblong bases allows for better adaptation to variations in chamber volume during operation, which improves the efficiency of compression and suction.

[0026] The difference in surface area between the proximal and distal bases of the pistons can contribute to better dynamic sealing, reducing internal leakage and thus increasing the overall performance of the compressor.

[0027] According to one embodiment, the suction disc is traversed by the drive shaft so that the drive shaft is distant from the suction disc.

[0028] According to one embodiment, the compressor comprises a casing enclosing the suction disc, the compression disc and the wheel, the suction disc and the compression disc each being fixed to the casing by means of a roller bearing.

[0029] Using a casing to enclose key compressor components protects them from external contaminants and physical damage, thus extending the compressor's lifespan.

[0030] Securing the suction and compression discs to the housing using roller bearings ensures precise alignment and smooth rotation, which reduces friction and wear on moving parts.

[0031] According to one embodiment, the wheel has a plurality of through ventilation ports located between the wheel's axis of revolution and the chambers.

[0032] The presence of through ventilation ports in the wheel allows for efficient dissipation of the heat generated during operation, which can prevent overheating and improve compressor reliability.

[0033] These openings also help to reduce the aerodynamic drag of the wheel as it rotates, which can result in reduced energy consumption and improved operational efficiency.

[0034] According to one embodiment, the suction disc has openings located between the suction pistons and the first axis of revolution, the openings being distributed regularly all around the first axis of revolution.

[0035] According to one embodiment, the compression disc has openings located between the compression pistons and the second axis of revolution, the openings being distributed regularly all around the second axis of revolution.

[0036] The reduced number of days allows for a decrease in the amount of material used and the weight of the compressor.

[0037] Days also help to reduce the aerodynamic drag of the compression or suction disc during its rotation, which can result in reduced energy consumption and improved operational efficiency.

[0038] The days help to improve the cooling of the pistons and the compressed air. Brief description of the figures

[0039] The invention will be better understood, and other objects, details, features and advantages thereof will become more apparent from the following description of several particular embodiments of the invention, given solely by way of illustration and not limitation, with reference to the accompanying drawings.

[0040] The figure represents a front view of the interior of a positive displacement piston compressor according to one embodiment, the wheel having been omitted.

[0041] Lare represents a cross-sectional view of a positive displacement piston compressor according to one embodiment.

[0042] This is a view of detail III of the, representing the pistons at top dead center (TDC).

[0043] This is a view of detail IV of the, representing the pistons at bottom dead center (BDC).

[0044] This is a perspective view of a wheel of a positive displacement piston compressor according to one embodiment.

[0045] The invention relates to an oil-free circular piston compressor, designated "CPC", which belongs to the category of medium-pressure oil-free positive displacement compressors. This compressor will be described in more detail with reference to Figures 1 to 5.

[0046] This compressor is designed to compress air or other gases without the risk of oil contamination, making it particularly suitable for applications requiring pure compressed air or gas. The CPC compressor uses an innovative mechanism based on oval-shaped pistons, enabling efficient compression and operation without a connecting rod and crankshaft between the moving parts.

[0047] As shown in Figures 1 and 2, the CPC compressor consists of several key elements: - Two discs (suction disc 2 and compression disc 6) inclined in opposite directions form the main structure of the compressor. These discs are fixed to create compression chambers between them within the impeller 12. - Oval-shaped pistons 3 and 7 are located at the periphery of the discs. Each piston is enclosed in a correspondingly shaped compression chamber 13, allowing axial movement without mechanical contact. - A central impeller 12 is integrated between the two discs 2 and 6 and contains the compression chambers 13. This impeller 12 is essential for the rotary motion that enables the compression and suction of the gases. - Each piston is equipped with valves 4 and 8 that regulate the inlet and outlet of the gases.The suction valves 4 allow air or gas to enter the compression chambers 13, while the compression valves 8 expel the compressed air.

[0048] Lamontre shows the internal layout and structure of the volumetric piston compressor 1. For clarity, wheel 12 has been omitted from this figure.

[0049] As can be seen in particular in the figure, the compressor 1 thus comprises a suction disc 2 including a plurality of suction pistons 3. Each suction piston 3 includes an inlet and an outlet. The outlet is fitted with a suction non-return valve 4.

[0050] The suction disc 2 has an inner surface oriented towards the wheel 12 and an outer surface opposite the inner surface. The suction pistons 3 are located on a periphery of the inner surface.

[0051] The suction disc 2 includes a gas supply circuit 5 configured to supply gas to the inlet of the suction pistons 3.

[0052] The compressor 1 also includes a compression disc 6 comprising a plurality of compression pistons 7. Each compression piston 7 includes an inlet fitted with a compression check valve 8 and an outlet.

[0053] The compression disc 6 has an inner surface oriented towards the wheel 12 and an outer surface opposite the inner surface. The compression pistons 7 are located on a periphery of the inner surface.

[0054] The compression disc includes a compressed gas evacuation circuit 9 connected to the outlet of the compression pistons 7 and configured to evacuate the compressed gas when the compression check valves 8 are opened.

[0055] Lamontre cross-section shows the internal arrangement of the elements of compressor 1, with wheel 12 shown this time.

[0056] As can be seen in, the compressor 1 has a rotating drive shaft 10 extending along a shaft axis 11. The drive shaft 10 is intended to be driven by a motor (not shown).

[0057] The compressor 1 also includes a wheel 12 comprising a plurality of chambers 13 passing through the wheel 12. The chambers 13 are located on a peripheral periphery of the wheel 12. The wheel 12 is more particularly represented in.

[0058] Each chamber 13 has a shape complementary to one of the suction pistons 3 and to one of the compression pistons 7 so that each chamber 13 houses at least partially one of the suction pistons 3 and one of the compression pistons 7.

[0059] The wheel 12 has a wheel axis of revolution coaxial with the shaft axis 11. The wheel 12 is rotationally fixed to the drive shaft 10 so that when the drive shaft 10 is driven in rotation by the motor, the latter drives the wheel 12 in rotation.

[0060] The rotation of the wheel 12 causes, due to the presence of the pistons 3, 7 in the chambers 13, the rotation of the discs 2, 6. In order to move the pistons 3, 7 from a top dead center (TDC) to a bottom dead center (BDC) and vice versa, the suction disc 2 has a first axis of revolution 14 inclined at a first angle of inclination with the shaft axis 11, and the compression disc 7 has a second axis of revolution 15 inclined at a second angle of inclination with the shaft axis 11. Advantageously, for reasons of balancing, the first angle of inclination and the second angle of inclination are opposite and for example equal to -4° and 4° respectively.

[0061] Figure 1 represents, more specifically, a suction piston 3 and a compression piston 7 in a chamber 13 at top dead center (TDC), that is, when the volume of chamber 13 is at its smallest. Figure 2 represents a suction piston 3 and a compression piston 7 in a chamber 13 at bottom dead center (BDC), that is, when the volume of chamber 13 is at its largest.

[0062] The operation of compressor 1 is based on a compression and suction cycle that takes place in two distinct phases: 1. **Suction Phase**: From TDC to BDC, as the pistons move outwards, they create a vacuum in chamber 13, allowing air or gas to enter through the suction valve 4. This phase occurs on one half of the disc, i.e., a 180° rotation. 2. **Compression Phase**: From BDC to TDC, the piston moves inwards, reducing the space in chamber 13. This results in an increase in the pressure of the trapped air or gas, which is then expelled through the compression valve and the compressed gas discharge circuit 9 located in the compression disc 6. This phase occurs on the other half of the disc, i.e., a 180° rotation.

[0063] As can be seen in particular in Figures 3 and 4, each suction piston 3 and each compression piston 7 has a sealing gasket 16 having a sealing lip 17 in contact with the chamber 13 housing said piston, and all around said piston. Advantageously, the sealing gasket 16 is made of a composite material comprising polytetrafluoroethylene (PTFE).

[0064] As shown in the figure, each chamber 13 has a cylindrical shape with a curved oblong base, or an ovoid shape, whose generatrices extend parallel to the wheel axis. The oblong base extends along an angular sector of the wheel 12, and the plurality of chambers 13 are regularly distributed around the peripheral perimeter.

[0065] To present a complementary shape, each suction piston 3 and each compression piston 7 have a frustoconical shape with curved oblong bases, as seen in. The oblong bases comprise a proximal base 18 fixed respectively to the inner surface of the suction disc 2 or the compression disc 6 and a distal base 19 located in one of the chambers 13. The distal base 19 has a larger surface area than the proximal base 18.

[0066] The compressor 1 also includes a housing 20, partially visible in, enveloping in particular the suction disc 2, the compression disc 6 and the wheel 12. The suction disc 2 and the compression disc 6 are each fixed to the housing 20 by means of a bearing 23.

[0067] As can be seen in, the wheel 12 has a plurality of through ventilation orifices 21 located between the wheel's axis of revolution and the chambers 13.

[0068] Similarly, discs 2, 6 have 22 through-days, visible in.

[0069] The oil-free circular piston compressor "CPC" represents a significant advancement in the field of positive displacement compressors. Its innovative design, extremely advantageous weight-to-volume ratio, low vibration compared to conventional piston compressors, efficient operation, and ability to deliver compressed air or gas without oil contamination make it an ideal choice for various industrial applications, particularly in the railway sector.

[0070] Although the invention has been described in connection with several particular embodiments, it is clearly evident that it is by no means limited to them and that it includes all technical equivalents of the means described as well as their combinations if these fall within the scope of the invention.

[0071] The use of the verb "comporter", "comprendre" or "include" and its conjugated forms does not exclude the presence of other elements or steps than those stated in a claim.

[0072] In claims, any reference sign in parentheses shall not be interpreted as a limitation of the claim.

[0073] 1 Compressor 2 Suction disc 3 Suction piston 4 Suction check valve 5 Gas supply circuit 6 Compression disc 7 Compression piston 8 Compression check valve 9 Compressed gas discharge circuit 10 Drive shaft 11 Shaft shaft 12 Impeller 13 Chamber 14 First axis of revolution 15 Second axis of revolution 16 Sealing gasket 17 Sealing lip 18 Proximal base 19 Distal base 20 Casing 21 Ventilation port 22 Day 23 Bearing

Claims

Oil-free positive displacement piston compressor (1) comprising: - a suction disc (2) comprising a plurality of suction pistons (3), each suction piston (3) comprising an inlet and an outlet equipped with a suction check valve (4), the suction disc (2) having an inner surface and an outer surface opposite the inner surface, the suction pistons being located on a periphery of the inner surface, the suction disc (2) comprising a gas supply circuit (5) configured to supply gas to the inlet of the suction pistons (3), - a compression disc (6) comprising a plurality of compression pistons, each compression piston (7) comprising an inlet equipped with a compression check valve (8) and an outlet, the compression disc (6) having an inner surface and an outer surface opposite the inner surface, the compression pistons (7) being located on a periphery of the inner surface,the compression disc (6) comprising a compressed gas evacuation circuit (9) connected to the outlet of the compression pistons (7) and configured to evacuate the compressed gas when the compression check valves (8) are opened; a rotating drive shaft (10) extending along a shaft axis (11), the drive shaft (10) being intended to be driven by a motor; a wheel (12) comprising a plurality of chambers passing through the wheel (12) and located on a peripheral periphery of the wheel (12), each chamber (13) having a shape complementary to one of the suction pistons (3) and to one of the compression pistons (7), each chamber (13) housing at least partially one of the suction pistons and one of the compression pistons, the wheel (12) having a wheel axis of revolution (12) coaxial with the shaft axis; the wheel (12) being rotationally fixed to the drive shaft (10),in which the suction disc (2) has a first axis of revolution (14) inclined at a first angle of inclination with the shaft axis, and the compression disc (6) has a second axis of revolution (15) inclined at a second angle of inclination with the shaft axis. Oil-free piston positive displacement compressor (1) according to claim 1, wherein the first angle of inclination is between 1 degree and 20 degrees, and the second angle of inclination is between -1 degree and -20 degrees. Oil-free piston positive displacement compressor (1) according to claim 1 or claim 2, wherein the first angle of inclination is opposite to the second angle of inclination. Oil-free piston positive displacement compressor according to any one of claims 1 to 3, wherein each suction piston (3) has a sealing seal (16) having a sealing lip (17) in contact with the chamber (13) housing said suction piston (3), all around said suction piston (3), and wherein each compression piston (7) has a sealing seal having a sealing lip in contact with the chamber (13) housing said compression piston (7), all around said compression piston (7). Oil-free piston volumetric compressor according to claim 4, in which the sealing gasket (16) is made of composite material comprising PTFE. Oil-free piston volumetric compressor according to any one of claims 1 to 5, in which each chamber (13) has a cylindrical shape with an oblong base whose generatrices extend parallel to the wheel axis (12), the oblong base extending along an angular sector of the wheel (12), the plurality of chambers being regularly distributed around the peripheral perimeter. Oil-free piston volumetric compressor according to claim 6, wherein each suction piston (3) and each compression piston (7) has a frustoconical shape with oblong bases, the oblong bases having a proximal base (18) fixed respectively to the internal surface of the suction disc (2) or the compression disc (6) and a distal base (19) located in one of the chambers, the distal base (19) having a surface greater than the proximal base (18). Oil-free piston volumetric compressor according to any one of claims 1 to 7, in which the suction disc (2) is traversed by the drive shaft (10) so that the drive shaft (10) is distant from the suction disc (2). Oil-free piston volumetric compressor according to any one of claims 1 to 8, in which the compressor comprises a casing (20) enclosing the suction disc (2), the compression disc (6) and the wheel (12), the suction disc (2) and the compression disc (6) each being fixed to the casing (20) by means of a roller bearing (23). Oil-free piston volumetric compressor according to any one of claims 1 to 9, in which the wheel (12) has a plurality of through ventilation ports (21) located between the axis of revolution of the wheel (12) and the chambers (13).

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