EP4007855A1

EP4007855A1 - Rotary piston pump, compressor or vacuum pump

Info

Publication number: EP4007855A1
Application number: EP20776254.3A
Authority: EP
Inventors: Lubos URBAN; Ján PAVLACKA
Original assignee: Up Steel SRO
Current assignee: Up Steel SRO
Priority date: 2019-08-02
Filing date: 2020-08-02
Publication date: 2022-06-08
Also published as: SK9206Y2; SK500572019U1; WO2021025628A1

Abstract

Rotary piston pump, compressor or vacuum pump comprising a housing (1), in which a cylindrical hole (11) for a cylindrical rotor (4) is provided, where the rotor (4) comprises an axial opening (41) for a shaft (7) of the pump, compressor or vacuum pump and at least two angularly offset chambers (42) arranged transversely to the rotor (4) axis, where a reciprocating piston (5) is placed in each chamber (42), which, the piston (5), is provided with an opening (53) for a circular cam (8) on the shaft (7) of the pump, compressor or vacuum pump, the shaft (7) being mounted eccentrically to the rotor (4), the housing (1) being provided with removable heads (2) with bearings (21) for the shaft (7) and for tight closing of the cylindrical hole (11) for the rotor (4), and the housing (1) further comprises at least one inlet opening (12) for supplying a medium to the piston (5) chamber (42) and at least one outlet opening (13) for discharging a medium of the piston (5) chamber (42), where the eccentricity of the axis of rotation of the shaft (7) from the axis of the cylindrical rotor (4) is equal to the eccentricity of the axis of the circular cam (8) from the axis of rotation of the shaft (7), where at least one cam (8) is mounted on the shaft (7) removably fixedly.

Description

Rotary piston pump, compressor or vacuum pump

Technical Field

[0001] The invention relates to rotary piston pump, compressor or vacuum pump comprising a rotor of circular section, in which chambers for pistons are formed, the pistons being mounted on circular cams to produce their linear reciprocating motion, and these cams are mounted on a shaft, which is eccentrically positioned in relation to the rotor. The eccentricity of axis of the shaft from axis of the rotor is equal to the eccentricity of the cam from the axis of the shaft.

Background Art

[0002] Pumps or compressors of said type are disclosed, for example, in documents US 1 853394, US 1 910876 and US 4723895.

[0003] Documents US 1 853394, US 1 910876 have the same inventor. Document US 1 853394, applicant D. Appel, discloses a rotary machine or pump, including a casing, a circular chamber within said casing having inlet and, outlet ports at opposite sides thereof. A cylinder rotatably confined within said chamber having an axial opening, a pair of working chambers extending at right angles to each other, diametrically through said cylinder and at opposite sides of said opening thereof. Pistons, within said working chambers having circular openings therein, and a revoluble shaft having a pair of diametrically related integral eccentrics. Eccentrics operating within said piston openings. Said shaft being eccentrically mounted with respect to the axis of said circular chamber. The respective diameters of said eccentrics, piston openings and axial cylinder opening being substantially equal and the diameters of said rotatable cylinder and said eccentrics being limited to dimensions, in which the axial opening of said rotatable cylinder is covered by each of said reciprocating pistons throughout its full stroke. Aim of the invention according to this document is to provide an exceptionally efficient rotary machine for raising, transferring or compressing liquids or gases.

[0004] Subsequent document US 1 910 867, of the same applicant, which refers to the document US 1 853 394, then discusses in more detail properties of described rotary pump. It is essential, with the pumps described in these documents, for the axial opening in the cylinder to be continuously covered by the pistons and never to be exposed, and thus no fluid could flow from one chamber of the cylinder to the other. This condition makes impossible to design a pump with the cylinder in one single piece, having a ratio of the pump rotor diameter and piston stroke of less than 5 to 1. This is because an assembling of the rotor with pistons can only be achieved by axially moving the drive shaft through the central opening of the rotor and circular openings in the pistons. In order to make such assembly possible, the central opening must have such cross section that the drive shaft with the eccentrics can easily rotate therein. In addition, the lateral distance between the piston chambers must be approximately the same as the diameter of the piston, to allow the drive shaft to rotate to the proper alignment of its eccentrics with respect to the circular openings of the pistons, after one of the eccentrics has been moved through the circular opening of one of the pistons. Consequently, pumps with a ratio of less than 5 to 1 would be provided with an opening of such dimension that the reciprocating pistons would not continuously cover this opening and thus these pumps would be unusable. Design of the pump in Figures 5 to 10 of the document US 1 910 867 has the ratio of approximately 6 to 1. In order to assemble pumps of this type with the ratio of less than 5 to 1, the rotor must be split to allow assembly with a smaller central opening.

[0005] However, the split rotor must show the same characteristics as a single piece rotor, and thus assembly of separate parts of the split rotor must be produced very precisely with minimal tolerances and also sufficiently rigid. Such embodiment increases manufacturing demands and thus also production costs.

[0006] Document US 4 723 895 discloses a method of and an apparatus for effecting volume control suitable for use with a compressor for compressing a compressible fluid, such as a refrigerant of the refrigeration cycle. A compressor is described in this document having a principle of operation of machines according to US 1 853 394, US 1 910 876. Respective rotating parts of the compressor are journalled by ball or roller bearings. The shaft of the compressor is formed integrally with circular cams. Each cam has such construction that the cam diameter is reduced without varying the eccentricity of the cam by causing a portion of the cam diametrically opposed to the protuberance of the cam to be disposed in a position nearer to the center of the shaft than its outer circumferential surface, and reliefs for assembling the pistons with the shaft are formed at the outer circumferential surface of the shaft in the vicinity of the portion of the cam diametrically opposed to the protuberance of the cam.

[0007] Said reliefs of the shaft are important for allowing the reduction in diameter of openings formed in the pistons, into which the cams are inserted to render possible the assembly of the shaft, the pistons and the rotor in described arrangement. Disadvantage of the compressor design according to the document US 4723895 resides in tis construction complexity derived especially from use of rolling element bearings.

[0008] Object of this invention is to design a construction of a pump, compressor or vacuum pump of the above described type, which is characterized by simplicity in manufacturing, while practically eliminating all disadvantages and limitations resulting from the constructions in the above disclosed documents. Such design of the pump, compressor or vacuum pump would allow the production of pumps or compressors for a wide range of applications and pressure ranges while maintaining the same construction arrangement.

Summary of Invention

[0009] Said object is achieved by rotary piston pump, compressor or vacuum pump according to this invention comprising a housing in which a cylindrical hole for a cylindrical rotor is provided, where the rotor comprises an axial opening for a shaft of the pump, compressor or vacuum pump and at least two angularly offset chambers arranged transversely to the rotor axis, where a reciprocating piston is placed in each chamber, which, the piston, is provided with an opening for a circular cam on the shaft of the pump, compressor or vacuum pump, the shaft being mounted eccentrically to the rotor, the housing being provided with removable heads with bearings for the shaft and for tight closing of the cylindrical hole for the rotor, and the housing further comprises at least one inlet opening for supplying a medium to the piston chamber and at least one outlet opening for discharging a medium of the piston chamber, where the eccentricity of the axis of rotation of the shaft from the axis of the cylindrical rotor is equal to the eccentricity of the axis of the circular cam from the axis of rotation of the shaft. The pump, compressor or vacuum pump according to this invention is characterized in that at least one cam is mounted on the shaft removably fixedly.

[0010] Preferably, the removable fixed mounting of the cam on the shaft is provided by a detachable connection and axial position of the cams and the shaft is secured by a cam stop on the shaft and a spacer arranged between the cam and the head of the housing of the rotary piston pump, compressor or vacuum pump. The most advantageous detachable connection of the shaft and the cam is a keyed joint. The cam stop on the shaft can preferably be formed by a shaft shoulder.

[0011] Preferably, the spacer is formed integrally with the head of the housing.

[0012] The spacer element may also preferably comprise a bearing for the rotor.

[0013] Main advantage of the invention is that the axial opening in the single piece cylindrical rotor can have a minimum possible diameter, i.e. only such a diameter is sufficient to allow a smooth rotation of the shaft eccentrically placed relative to the rotor, and also such as to allow mounting the cams onto the shaft through this opening when assembling the pump, compressor or vacuum pump. It is not necessary for the axial opening in the rotor between the piston chambers to have a diameter at least such that the shaft formed in one piece with the cams can easily pass through it, as it is in the construction described in the prior art. This opening in prior art pumps has a minimum diameter as is the diameter of a circle drawn by the cam during rotation of the shaft, what is then resulting in disadvantages described in the prior art. The pump, compressor or vacuum pump according to this invention thus can be produced with different ratios of rotor diameter and piston stroke without a necessity to assemble a rotor from several parts as stated in the prior art, for certain values of these ratios and the rotor can always be realized as a single piece body. This then ensures the construction simplicity of the rotor as well as the strength of the rotor body.

[0014] If the spacer, for limiting the cam and shaft axial position arranged between the cam and the head closing the housing of the pump or compressor, is formed in one piece with the head closing the housing of the pump or compressor, this spacer then provides a shaft bearing which supports the shaft over a length substantially from the outer edge of the head of the housing extending up to the inside of the rotor up to the cam on the shaft. Such bearing then provides a very good support for the shaft, especially for high-pressure use of the pump or compressor, where these bearings ensure that the geometry of the circular eccentric mechanism required for the operation of the pump or compressor is maintained.

[0015] In the case of pumps, compressors or vacuum pumps for high loads, it is also preferred to kinetically connect the shaft and the rotor, such that the rotor would be driven in rotation simultaneously by both the pistons and the shaft of the pump or compressor shaft.

[0016] It is preferred for the rotary piston compressor, if the shaft comprises channels and/or openings for a lubricant to distribute the lubricant under pressure to the friction surfaces of the moving parts of the compressor, where the channels and/or openings for the lubricant provided on the shaft are connected to channels and/or openings for the lubricant in moving and/or stationary parts of the compressor, with a lubricant inlet to the compressor and a lubricant outlet from the compressor.

[0017] A lubrication of the rotary piston compressor is also preferred such that the lubricant outlet is only to the space between the piston wall and the piston chamber wall.

[0018] A lubrication of the rotary piston compressor is also preferred such that a lubricant pump is coupled to the shaft and connected to the lubricant inlet and the channels and/or openings for the lubricant.

[0019] Preferably, the lubricant pump is a vane pump having at least one vane, the vane being placed in a groove at the end of the shaft. The shaft end with the vane is inserted in a chamber of the lubricant pump formed in a housing of the lubricant pump attached to the head of the compressor housing. [0020] It is preferred for the rotary piston vacuum pump, if the shaft comprises channels and/or openings for a lubricant to distribute the lubricant under pressure to the friction surfaces of the moving parts of the vacuum pump, where the channels and/or openings for the lubricant provided on the shaft are connected to channels and/or openings for the lubricant in moving and/or stationary parts of the vacuum pump, to the lubricant inlet to the vacuum pump and the lubricant outlet from the vacuum pump. A lubricant pump is then coupled to the vacuum pump shaft and connected to the lubricant inlet and channels and/or openings for the lubricant.

[0021] Preferably, the lubricant pump for the rotary piston vacuum pump is a vane pump having at least one vane, the vane being placed in a groove at the end of the shaft. The shaft end with the vane is inserted in a chamber of the lubricant pump formed in a housing of the lubricant pump attached to the head of the vacuum pump housing.

Brief Description of Drawings

[0022] The invention is for better understanding illustrated in the attached drawings, in which:

[0023] Fig. 1 shows an axonometric exploded view of the pump, compressor or vacuum pump according to this invention;

[0024] Fig. 2 shows a side sectional view of the pump, compressor or vacuum pump according to this invention, as assembled;

[0025] Fig. 3 schematically shows the working phases of the pump, compressor or vacuum pump according to this invention;

[0026] Fig. 4 shows an axonometric exploded view of the compressor or vacuum pump according to this invention with a lubrication system;

[0027] Fig. 5 shows a side sectional view of the compressor or vacuum pump according to this invention, as assembled, with the lubrication system;

[0028] Fig. 6 shows a cross-section of a lubricant pump for the lubrication system of the compressor or vacuum pump of Fig. 4 and Fig. 5.

Description of Embodiments [0029] A rotary piston pump, compressor or vacuum pump according to this invention is further described and explained in examples of embodiments with reference to the figures. The pump, compressor or vacuum pump, according to the figures, is designed as a two-cylinder, i.e. with two chambers 42 for the pistons 5.

[0030] The pump, compressor or vacuum pump comprises a housing 1 of the pump, compressor or vacuum pump with inlet openings 12 for the supply of a medium to the chamber 42 of the piston 5 and outlet openings 13 for the outlet of the medium from the chamber 42 of the piston 5. The housing 1 comprises a cylindrical hole 11 for a cylindrical rotor 4. The housing 1 is provided with removable heads 2 with bearings 21 for a shaft 7 and for tight closure of the cylindrical hole 11.

[0031] The rotor 4 comprises an axial opening 41 for the shaft 7 of the pump, compressor or vacuum pump. Two chambers 42 for the pistons 5 are formed in the rotor 4, transversely to the axis of the rotor 4. In the example shown, the chambers 42 are placed at an angle of 90° with respect to each other. One reciprocating piston 5 is placed in each chamber 42.

[0032] The piston 5 is realized as a symmetrical body with two ends 51, 52, where the end surfaces 51, 52 of the piston 5 are rounded with the outer cylindrical surface of the rotor 4. In the example shown, the piston 5 has cylindrical shape and the chambers 42 are then respectively cylindrical. However, the shape of the pistons 5 may also be other than cylindrical. The piston 5 may also have a cross- section e.g. rectangular, square, polygonal, elliptical, and the like. The piston 5 is provided in the center with an opening 53 for a circular cam 8, which provides for the reciprocating movement of the piston 5.

[0033] The circular cam 8 is mounted on the shaft 7. The shaft 7 is mounted eccentrically with respect to the rotor 4. The eccentricity of the axis of rotation of the shaft 7 from the axis of the cylindrical rotor 4 is equal to the eccentricity of the axis of the circular cam 8 from the axis of rotation of the shaft 7.

[0034] The circular cam 8 is removably fixedly mounted on the shaft 7. This means that there is a connection between the cam 8 and the shaft, which allows the cam 8 to be mounted on, or removed from the shaft and at the same time the cam 8, mounted on the shaft in the desired position, does not move relative to the shaft 7, i.e. it can neither rotate on the shaft 7 nor move along the shaft 7 freely. A movement of the cam 8 on the shaft 7 within the manufacturing tolerances is not considered to be a free movement of the cam 8 on the shaft.

[0035] In the embodiments described and shown in the figures, both cams 8 are removably fixedly mounted on the shaft 7. As will be described further in the text, in the description of assembly of the pump or compressor according to the invention, it is also possible to realize the shaft 7 such that it will already comprise one cam 8 formed together with the shaft 7, i.e. not removably fixedly, but only fixedly on the shaft 7. However, in this way, the shaft 7 can be formed with one cam 8 only, where, in the case of more than two-cylinder design, this fixed cam 8 would have to be arranged in a position on the shaft 7 closest to the center of the rotor 4.

[0036] In the example of embodiment shown, detachable connection of the cam 8 and the shaft 7 is realized by a keyed joint. In the shaft 7, at the location of the cam 8, a keyway 71 for a key 6 is provided in the conventional manner, and in the cam 8, a hole 81 for the shaft 7 with a keyway for the key 6 is then provided in the conventional manner. This detachable connection can be realized also by other known joints for this purpose, such as e.g. splines, pin joints, etc. The keyed joint used appears to be the most advantageous in regard of manufacturing and assembly of the pump, compressor or vacuum pump.

[0037] The shaft 7 and the cams 8 must also be secured within the pump, compressor or vacuum pump against axial movement, i.e. against axial movement relative to the housing 1 of the pump, compressor or vacuum pump.

[0038] In the embodiment shown, this axial position of the shaft 7 and the cams 8 is secured a stop 72 of the cam 8 on the shaft 7 and a spacer 3 arranged between the cam 8 and the head 2 of the housing 1.

[0039] In the embodiment shown, the stop 72 on the shaft 7 is in the form of a shaft shoulder 7. This stop 72 can also be realized in another form, e.g. shaft retaining ring, a so. However, the embodiment of the stop 72 shown, is the most advantageous and practically simplest in regard of the production.

[0040] In the preferred embodiment shown, the spacer 3 is provided in one piece with the head 2, i.e. the head 2 is practically formed into an extension protruding to the inside of the rotor 4 up to the respective cam 8.

[0041] The head 2 thus formed provides a bearing for the shaft 7, which supports the shaft 7 over a length substantially from the outer edge of the head 2 of the housing 1 up to the cam 8 on the shaft 7. Such bearing provides a very good support of the shaft 7 especially for a high pressure use of the pump or compressor, in the case of the vacuum pump in creating high vacuum, where these bearings ensure that the geometry of the circular eccentric mechanism is maintained. The geometry of the circular eccentric mechanism could be affected at high pressures by bending the shaft 7, which would block the rotational movement and interrupt the operation of the pump, compressor or vacuum pump.

[0042] The spacer 3, if necessary, can also be realized as a separate element, e.g. in the form of a ring or bush and the like, put onto the shaft 7 between the cam 8 and the head 2 of the housing 1. In this case, however, the load capacity of the bearing of the shaft 7 in the head 2 is reduced. This may be advantageous for lower working loads, and then the head 2 can be a simple workpiece.

[0043] Although the means for securing the cam 8 and the shaft 7 against axial movement, i.e. the stop 72 and the spacer 3 are described in the above description for one cam 8 at one end of the housing 1, these means are analogous also for the other cam 8, thus at the other end of the housing 1.

[0044] If necessary, preferably for example in pumps, compressors or vacuum pumps for high loads, an embodiment is also possible, in which also a bearing for the rotor 4 is formed at the spacer 3. Thus, a bearing surface is provided on the inside of the rotor 4 end and the corresponding bearing surface is then provided on the spacer 3. Here, the spacer 3 can be realized in one piece with the head 2, but it can also be realized separately, e.g. in the form of a ring or bush and the like put onto the shaft 7 between the cam 8 and the head 2, as described above. [0045] In the case of pumps, compressors or vacuum pumps for high loads, it is also preferred to kinetically connect the shaft 7 and the rotor 4, i.e. driven shaft 7 would also rotate the rotor 4, which is otherwise rotated by the pistons 5 only that are driven by the shaft 7. This connection of the shaft 7 and the rotor 4 can be realized by any known transmission means, e.g. gears, toothed belt, chain drive, and the like, in a ratio such that the rotor 4 makes one revolution per two revolutions of the shaft 7.

[0046] Method of operation of the rotary piston pump or compressor according to this invention is described further with reference to Fig. 3. The pump, compressor or vacuum pump is shown in Fig. 3 in cross section, seen from the protruding end of the shaft 7, to which a drive of the pump, compressor or vacuum pump is connected. In the case of the vacuum pump, it is clear that the inlet opening 12 of a medium is connected to a space, in which underpressure or vacuum is to be created.

[0047] The shaft 7 is rotated in the direction shown by the arrow R, clockwise. The figure shows positions of the rotating parts successively after the rotation of the shaft by 90°, while for the sake of clarity, one extreme position of one of the pistons 5 is set as the starting position, i.e. the position at the end of the stroke of the piston 5 in the chamber 42. This starting position is in the upper row at the position 0°. The lower row then represents corresponding positions of the second piston 5 in the perpendicular arrangement of the two pistons.

[0048] In the starting position according to Fig. 3, the cam 8 is in the extreme position of maximum eccentricity, the piston 5 is thus in the extreme position at the end of the piston 5 stroke. One end 51 of the piston 5 is closest to the wall of the cylinder hole 11 for the rotor 4. Surface of the end 51, 52 of the piston 5 copies the inner surface of the cylindrical hole 11 for the rotor 4 and in this extreme position the surface of the end 51 of the piston 5 is matching with the inner surface of the hole 11 for the rotor 4 and are almost in contact. Flowever, these surfaces must not actually come into contact. The other end 52 of the piston 5 is then farthest from the wall of the cylindrical hole 11 for the rotor 4. In this position, the rotor body 4, preferably with an overlap, closes the inlet opening 12 for the medium, liquid or gas, and the outlet opening 13 for the outlet of this medium. Likewise, the chamber 42 is also closed with an overlap by the body of the housing 1 of the pump or compressor. These overlaps provide sufficiently tight closing of the chamber 42 and the openings 12, 13 in this extreme position to avoid undesired backflow of the medium through the pump, compressor or vacuum pump, thus replace non-return valves.

[0049] In the mentioned phase, at one side of the end 51 of the piston 5, the medium is substantially completely pushed out of the chamber 42, and on the opposite end 52 of the piston 5 it is sucked into the maximum working volume of the chamber 42 defined by the wall of the chamber 42, the surface of the end 52 of the piston 5 and the surface of the cylindrical hole 11 for the rotor 4.

[0050] By rotating the shaft 7, shown in the position 90°, at one side the body of the rotor 4 passes beyond the edge of the inlet opening 12 while opening the chamber 42 into the inlet opening 12 and simultaneously, at the other side the body of the rotor 4 passes beyond the edge of the outlet opening 13 while opening the chamber 42 into the outlet opening 13. For a pump, i.e. when pumping liquids, the opening of the chamber 42 into the openings 12, 13 must occur simultaneously, due to the incompressibility of liquids. For compressors, according to pressure needs, the edge of the outlet opening 13 can be shifted such that the body of the rotor 4 opens the outlet opening 13 later, thus with decreasing of the working volume of the chamber 42 such closed relative to the outlet opening 13 by the body of the rotor 4, compression of the gas occurs.

[0051 ] By further rotation of the shaft 7, at one end 52 of the piston 5 the volume of the chamber 42 above the piston 5 decreases and at the other end 51 of the piston 5 the volume of the chamber 42 above the piston 5 increases, thus the medium is at one side pushed out into the outlet opening 13, and at the other side sucked in through the inlet opening 12.

[0052] In the position 180° in Fig. 3, the piston 5 is in the middle position. In the example shown, the chamber 42 is fully opened at both ends 51 , 52 of the piston 5 into the inlet opening 12 and the outlet opening 13, respectively, i.e. the body of the rotor 4, in the example shown, does not interfere with the openings 12, 13 by any of its portion.

[0053] By further rotation of the shaft 7, which is shown in the position 270°, the volume of the chamber 42 at one end 52 of the piston 5 decreases, continuing to push the medium out of the chamber 42 of the piston 5, and the volume of the chamber 42 at the other end 51 of the piston 5 increases, continuing the suction of the medium into the chamber 42.

[0054] After finishing the entire cycle, by one revolution of the shaft 7, shown in the position 360°, the piston 5 at one end 52 is closest to the wall of the cylindrical hole 11 for the rotor 4 and at the other end 51 farthest from the wall of the cylindrical hole 11 for the rotor 4. In this position, the body of the rotor 4 closes again the inlet opening 12 for the supply of the medium, liquid or gas, and the outlet opening 13 for the outlet of this medium, so that no backflow of the medium can occur.

[0055] When producing the rotary piston compressor or vacuum pump according to this invention, it is also preferred to provide lubrication of the moving parts. An example of embodiment of a compressor or vacuum pump according to this invention with lubrication, is shown in Fig. 4 to Fig. 6.

[0056] The arrangement of the parts of the compressor or vacuum pump is the same as in the example described above with reference to Fig. 1 and 2. For a compressor or a pump, the heads 2 of the housing 1 are preferably provided with seals 14, e.g. known sealing rings.

[0057] To provide lubrication, a pump 10 for a lubricant, usually oil, is then connected to the compressor or vacuum pump, and the parts of the compressor or vacuum pump, i.e. the shaft 7, the cams 8, the pistons 5, the heads 2, the housing 1, optionally the rotor 4, comprise channels and/or openings 9 for a lubricant to distribute the lubricant under pressure to the friction surfaces of the moving parts of the compressor or vacuum pump, and also then leading the lubricant away from said parts. The lubricant pump 10 in the example of embodiment shown in Fig. 4 to 6, is a simple vane pump driven directly by the shaft 7 of a compressor or a vacuum pump according to this invention. The lubricant pump 10 is composed by a housing 101 with a chamber 102, in which vanes 103 move. The housing 101 is provided with an inlet 91 of the lubricant to the compressor or vacuum pump, which in this case leads into the chamber 102, and by lubricant channels and/or openings to respective friction surfaces of the parts of compressor or vacuum pump. In the example shown, the housing 101 is attached by screws 106 to one head 2 of the housing 1 of the compressor or vacuum pump. The shaft 7 passes through the head 2 into the chamber 102 of the lubricant pump 10. The shaft 7 is provided at this end with a groove 105 for the vanes 103 of the lubricant pump 10. A spring 104 is arranged between the vanes 103, which pushed the vanes 103 against the wall of the chamber 102. Depending on the required lubricant pressure, e.g. if small lubricant discharge volume is required, the lubricant pump 10 can have only one vane 103 in the groove 105 of the shaft 7. Of course, it is also possible to realize such vane pump with a different number of vanes than known from vane pumps setups.

[0058] The lubricant is led from the pump 10 by channels and/or openings 9 for the lubricant provided in the shaft 7 and also in other moving and/or stationary parts of the compressor or vacuum pump, to the respective friction surfaces of the parts of the compressor or vacuum pump, in particular to the sliding bearing of the piston 5 and the circular cam 8, the sliding surfaces of the piston 5 and the piston chamber 42, the sliding bearings of the shaft 7 in the heads 2, and the sliding bearing of the rotor 4 in the cylindrical hole 11 in the housing 1. The lubricant, after passing through the lubrication system, then leaves through a lubricant outlet 92, in the embodiment shown, through the lubricant outlet 92 in the heads 2.

[0059] In general, the lubricant inlet 91 as well as the lubricant outlet 92 can be realized also on other parts of the compressor or vacuum pump as described in the examples shown. These are practically all externally accessible parts of the compressor or vacuum pump, such as for example the housing 1, any of the heads 2, the shaft 7 and the like. It is understood that the lubricant inlet 91 and the lubricant outlet 92 may be formed by a single lubricant inlet 91 and outlet 92 as well as multiple lubricant inlets 91 and outlets 92 depending on given lubrication needs, construction, placement of the compressor or vacuum pump, and the like.

[0060] Also, an embodiment of the compressor is possible where the lubricant outlet 92 is not led out on the outer sides of the housing 1, the heads 2, the shaft 7 and the like, but the lubricant is actually pressed into the outlet opening 13 for the medium around the pistons 5. The lubricant is then separated from the gaseous medium in a known manner and led to the lubricant inlet 91. In this case, for efficient lubrication, it is necessary to maintain the condition that the outlet pressure of the lubricant pump 10 is equal to or greater than the outlet pressure of the compressor, so that no compressed gas is forced into the lubricant.

[0061] Also, an embodiment of the compressor is possible with lubrication but without the lubricant pump 10. The lubricant outlet 92 is also not led out on the outer sides of the housing 1, the heads 2, the shaft 7 and the like, but the lubricant is pressed into the outlet opening 13 for the medium around the pistons 5. The outlet opening 13 is then connected to a lubricant separator, in which a lubricant reserve is created and supplied by the lubricant separated from the compressed gas. After separation, the compressed gas then leaves the separator, and at the same time the compressor outlet pressure exerts on the level of the lubricant reserve. The lubricant is then led from the separator to the lubricant inlet 91, into which it is forced by the gas pressure in the separator. Said lubrication can also be performed such that the entire compressor is in a closed pressure vessel, in which the lubricant separator and the lubricant supply are both present. The part of the compressor with the lubricant inlet 91 is then preferably immersed in said lubricant reserve. Then, on the outside of said pressure vessel only the inlet of gaseous medium and the outlet of compressed medium are present.

[0062] The lubricant, besides lubrication, also performs a sealing function, in sealing of the working space defined by the end 51, 52 of the piston 5, the wall of the piston chamber 42, and the wall of the housing 1. Due to the fact that the lubricant is supplied to the lubrication system of the compressor or vacuum pump under sufficient pressure, the lubricant also performs a centering function for the rotating parts such is the shaft 7 in the bearings 21, and the circular cam 8 in the opening 53 for the cam. This facilitates maintaining the precise geometrical arrangement of the parts, which is important for the smooth operation of the compressor or vacuum pump according to this invention.

[0063] In the case of large compressors or vacuum pumps, it is preferred to connect an external lubricant pump to the lubricant inlet 91 and to push the lubricant into the lubrication system of the compressor or vacuum pump before starting the compressor or vacuum pump itself. This prevents "dry" starting, and also thanks to the pressure of the lubricant, relevant parts of the compressor or vacuum pump are centered, which ensures a smooth start of the compressor or vacuum pump. After the compressor or vacuum pump is started, the external pump is disconnected and further lubrication is provided either by own lubricant pump 10 or also by the lubrication methods mentioned above, i.e. by pressure through the outlet opening 13 for the medium. The external pump can advantageously use directly the own lubricant reserve of the compressor or the pump.

[0064] The compressor or vacuum pump with the lubrication system described above operates in the same way as described above with reference to Fig. 3.

[0065] In the case of a pump, without a lubrication system, the lubrication and the above functions are usually provided directly by the pumped medium.

[0066] The compressor according to this invention can also be produced without the described lubrication system, that means as is described with reference to Fig. 1 and 2. Then, materials which do not require lubrication can be used for the respective friction parts, or a lubricant can optionally be injected in small amounts or sucked into the compressed gaseous medium. In the case of oil-free compressors, water can also be advantageously used as a lubricant.

[0067] Rotary piston pump, compressor or vacuum pump according to this invention as described in the above example of embodiments and shown in the figures, and also in other embodiments in accordance with the characteristic features of this invention, can be assembled in a way described further. [0068] In the first step, all, in the example shown both, the pistons 5 without the circular cams 8 are inserted into the rotor 4, such that the openings 53 in the pistons 5 are passable for the shaft 7. In the next step, the shaft 7 with one cam 8 mounted thereon, the cam 8 mounted removably fixedly or fixedly only, is inserted into the rotor 4 from one side, the shaft 7 being inserted into the rotor 4 with its end without the cam 8. The shaft 7 is thus inserted up into the opening 53 of the next piston 5.

[0069] In the case of a number of pistons of more than two, firstly, the cam 8, which will be in the middle, or closest to the center of the rotor 4 is mounted on the shaft 7. This cam 8 may optionally be fixed, i.e. formed as an integral part of the shaft 7. Next cams 8 are then inserted from the side of the respective ends of the shaft 7.

[0070] In the next step, the piston 5, in which the cam 8 is already inserted is moved to the extreme position. The piston 5, where the cam 8 is not yet inserted, is moved to the central position, i.e. such that the outer diameter of the cam 8 and the inner diameter of the rotor 4 are coaxial, on one axis. In the next step, the second, or another cam 8 in a row is inserted, that is mounted on the shaft 7 and to the opening 53, from the other side of the rotor 4.

[0071] The rotor assembly 4 thus completed with the pistons 5, the cams 8 and the shaft 7 is inserted into the cylindrical hole 11 into the housing 1. The heads 2 are then put onto the shaft 7 from each side, by which, the housing 1 of the pump or compressor is closed.

[0072] Then, a drive (not shown) can be connected to the shaft 7 of the assembled pump, compressor or vacuum pump for use; e.g. pipes, tubes, ports, and the like to supply and discharge of the pumped or compressed medium can be connected to the inlet opening/openings 12 for the supply of a medium and to the outlet opening/openings 13 for the outlet of a medium; in the case of the compressor or vacuum pump with the lubrication then e.g. pipes, tubes, ports, and the like, for the inlet and outlet of a lubricant to and from the compressor or vacuum pump can be connected to the lubricant inlet 91 and the lubricant outlet 92. [0073] The above described examples of embodiments with reference to the accompanying drawings are provided only to explain the characteristic features of the invention, and these are examples of particular embodiments of the pump, compressor or vacuum pump according to this invention, which are not intended to limit this invention to the specific examples described and shown in the drawings in any way.

[0074] Other embodiments of pumps, compressors or vacuum pumps are also possible, which may have a different number of the pistons 5, a different angular offset of the pistons 5, a different shape of the ends 51, 52 of the pistons 5, a different shape of the chambers 42 for the pistons 5 than cylindrical, other types of used connecting means such as screws, and the like. Also, embodiments with different sizes of pistons 5 and correspondingly chambers 42 for pistons are possible. Such arrangement is advantageous, for example, in the construction of a multistage compressor, where the size of the pistons 5 and thus also of the chambers 42 gradually decreases, e.g. to the high pressure outlet, and thus the outlet opening 13 for the medium from one chamber 42 is then connected to the inlet opening 12 for the medium to another chamber 42 in the respective row of chambers 42 with pistons 5.

[0075] Regarding the tightness of the pump, compressor or vacuum pump according to this invention, it is also possible to use other sealing means of the respective parts than those described, e.g. known shaft seals, sealing rings, and the like.

[0076] However, it should be noted that even in the embodiments described and shown, the pump, compressor or vacuum pump is very efficient rotary machine having smooth balanced and quiet operation, having simple construction with low production and operating costs.

[0077] The pump, compressor or vacuum pump according to this invention can be manufactured by commonly available and used technological processes and with common materials. The use of special materials is envisaged for special applications only such as oil-free compressors, pumps or compressors for extreme loads, and the like. [0078] The use of rolling element bearings, which could be considered for pumps or compressors of larger dimensions, is also not excluded, but sliding bearings are completely sufficient for the widest practical use.

Industrial Applicability

[0079] Rotary piston pump according to this invention can practically be used for all known pump applications.

[0080] Rotary piston compressor according to this invention can be used for a wide range of applications in a wide range of pressures and flow rates, for example as blowers, low-pressure, medium-pressure or high-pressure compressors.

[0081] Rotary piston vacuum pump according to this invention can be used as an efficient vacuum pump to create a vacuum, as well as a multi-stage pump to achieve a high vacuum. The vacuum pump is produced simply by connecting the inlet opening 12 as the inlet of the vacuum pump without any further constructional modifications.

Claims

[Claim 1] jRotary piston pump, compressor or vacuum pump comprising a housing, in which a cylindrical hole for a cylindrical rotor is provided, where the rotor comprises an axial opening for a shaft of the pump, compressor or vacuum pump and at least two angularly offset chambers arranged transversely to the rotor axis, where a reciprocating piston is placed in each chamber, which, the piston, is provided with an opening for a circular cam on the shaft of the pump, compressor or vacuum pump, the shaft being mounted eccentrically to the rotor, the housing being provided with removable heads with bearings for the shaft and for tight closing of the cylindrical hole for the rotor, and the housing further comprises at least one inlet opening for supplying a medium to the piston chamber and at least one outlet opening for discharging a medium of the piston chamber, where the eccentricity of the axis of rotation of the shaft from the axis of the cylindrical rotor is equal to the eccentricity of the axis of the circular cam from the axis of rotation of the shaft, characterized in that, at least one cam (8) is mounted on the shaft (7) removably fixedly.

[Claim 2] Rotary piston pump, compressor or vacuum pump according to claim 1, characterized in that, the removable fixed mounting of the cam (8) on the shaft (7) is provided by a detachable connection and axial position of the cams (8) and the shaft (7) is secured by a cam (8) stop (72) on the shaft (7) and a spacer (3) arranged between the cam (8) and the head (2) of the housing (1) of the rotary piston pump, compressor or vacuum pump.

[Claim 3] Rotary piston pump, compressor or vacuum pump according to claim 2, characterized in that, the detachable connection of the shaft (7) and the cam (8) is a keyed joint, and the cam (8) stop (72) on the shaft (7) is formed by a shaft (7) shoulder.

[Claim 4] Rotary piston pump, compressor or vacuum pump according to claim 2 or 3, characterized in that, the spacer (3) is formed integrally with the head (2).

[Claim 5] Rotary piston pump, compressor or vacuum pump according to any of claims 2 to 4, characterized in that, the spacer (3) comprises a bearing for the rotor (4).

[Claim 6] Rotary piston pump, compressor or vacuum pump according to any of preceding claims, characterized in that, the shaft (7) is kinetically connected with the rotor (4).

[Claim 7] Rotary piston compressor according to any of preceding claims, characterized in that, the shaft (7) comprises channels and/or openings (9) for a lubricant to distribute the lubricant under pressure to the friction surfaces of the moving parts of the compressor, where the channels and/or openings (9) for the lubricant provided on the shaft (7) are connected to channels and/or openings (9) for the lubricant in moving and/or stationary parts of the compressor, with a lubricant inlet (91) to the compressor and a lubricant outlet (92) from the compressor.

[Claim 8] Rotary piston compressor according to claim 7, characterized in that, the lubricant outlet (92) is only to the space between the wall of the piston (5) and the wall of the chamber (42) for the piston (5).

[Claim 9] Rotary piston compressor according to claim 7 or 8, characterized in that, the lubricant pump (10) is coupled to the shaft (7) and connected to the lubricant inlet (91) and the channels and/or openings (9) for the lubricant.

[Claim 10] Rotary piston compressor according to claim 9, characterized in that, the lubricant pump (10) is a vane pump having at least one vane (103), the vane (103) being placed in a groove (105) at the end of the shaft (7), where the shaft (7) end with the vane (103) is inserted in a chamber (102) of the lubricant pump (10) formed in a housing (101) of the lubricant pump (10) attached to the head (2) of the compressor housing (1).

[Claim 11] Rotary piston vacuum pump according to any of claims 1 to 6, characterized in that, the shaft (7) comprises channels and/or openings (9) for a lubricant to distribute the lubricant under pressure to the friction surfaces of the moving parts of the vacuum pump, where the channels and/or openings (9) for the lubricant provided on the shaft (7) are connected to channels and/or openings (9) for the lubricant in moving and/or stationary parts of the vacuum pump, to the lubricant inlet (91) to the vacuum pump and to the lubricant outlet (92) from the vacuum pump, where a lubricant pump (10) is coupled to the shaft (7) connected to the lubricant inlet (91) and channels and/or openings (9) for the lubricant.

[Claim 12] Rotary piston vacuum pump according to claim 11, characterized in that, the lubricant pump (10) is a vane pump having at least one vane (103), the vane (103) being placed in a groove (105) at the end of the shaft (7), where the shaft (7) end with the vane (103) is inserted in a chamber (102) of the lubricant pump (10) formed in a housing (101) of the lubricant pump (10) attached to the head (2) of the vacuum pump housing (1). |