WO2007107503A1

WO2007107503A1 - Piston unit of rotary pump

Info

Publication number: WO2007107503A1
Application number: PCT/EP2007/052486
Authority: WO
Inventors: Oleg PRÕGUNOV; Vladislav Nikitenko; Zanna Gasimova
Original assignee: SNC Promex AS
Priority date: 2006-03-21
Filing date: 2007-03-16
Publication date: 2007-09-27
Also published as: EE00618U1

Abstract

The invention relates to the piston unit of a rotary pump, comprising a rotor 4 placed on the pump shaft 6, a piston 3 placed in the groove 10 of the rotor 4, an insert block 8 placed in the cutout 11 of the piston 3, and a collar 2 to swivel the piston 3 relative to the rotor 4 in the groove 10 of the rotor 4. In the assembled pump the piston 3 is placed in the groove 10 of the rotor 4 and the insert block 8 is in turn placed in the cutout 11 of the piston 3. Two working chambers A and B with changing volume are formed in the cutout 11 of the piston 3 one on each side of the insert block 8 placed on the pump shaft 6, when in the operating pump by revolving the pump shaft 6, the piston 3 swivels in the groove 10 on the rotor 4 with the help of the collar 2.

Description

PISTON UNIT OF ROTARY PUMP

Technical field

This invention relates to a piston unit for a rotary pump. Specifically the invention relates to a piston unit, which is provided for a positive displacement twin pump, i.e. pump with two pumping sides, which has one common intake channel on the suction side and one common outlet channel on the outlet side of the pump and which is intended for pumping fluid medium.

Background art

In the United States patent US 1 692 473 (William J. Smith, published on 20.11.1928, international patent classification index F04C 23/00) is known a plate pump with two identical pumping sides. This twin pump has for each side of the pump one common intake channel and one common outlet channel. The running cycle of the first and second side of the pump is shifted in relation to one another by 90 degrees. Both sides of the pump are placed on a common axis.

In the United States patent US 4 552 079 (Plenty Limited, published on 05.11.1985, international patent classification index F04C 11/00) is known a sliding vane type pump with two pumping sides. This pump has also for each pumping side of the pump one common intake channel and one common outlet channel. The running cycle of the first and second pumping side is shifted in relation to one another in order to reduce pulsation in the outlet of the pump. Both pumping sides of the pump are placed on a common axis.

In the United States patent US 1 967 167 (William Weis et a/., published on 17.07.1934, international patent classification index F04C 3/06) is known a two- sided rotary piston pump with spherical piston (rotor). This pump has a piston with a spherical outer surface with a through bore, where the rotor of the pump is placed. Additionally the piston is provided with another transverse bore for the rotor, where in the assembled state of the pump the pump shaft is. The piston can swivel back and forth on the rotor, and as the position of the pump shaft during rotation in its bore changes, working chambers with changing volume are formed. The piston is put to swivel back and forth by turning of the pump shaft with the help of a collar, the plane of the collar being at an angle in respect of the axis of the pump shaft. The centre point of the collar coincides with the centre points of diameters of spherical outer surfaces of the rotor and the piston, that in the assembled state of the pump all are in an axis of the pump shaft.

The disadvantages of the design of the last mentioned pump are vibration related problems and the circumstance that due to the configuration of the parts of the piston unit this pump is not suitable for mass production.

The objection of the present invention is to provide a piston unit of the rotary pump suitable for industrial mass production and where in the disadvantages of the previously known solutions are rendered to a minimum. This objection is achieved by the following design of the piston unit.

Disclosure of the invention

The present invention relates to a piston unit, the main parts of which comprise a rotor, placed on the pump shaft in the concave spherical inner surface of the pump housing, a piston placed on the rotor, an insert block placed in the cutout of the piston and positioned on the pump shaft, and a collar for moving the piston in relation to the rotor.

The piston unit of the rotary pump disclosed in the present invention is intended to be used primarily in the twin rotary pump, i.e. in the rotary pump with two pumping sides. The pump housing comprises two concave spherical inner surface sides on the common axis, which are directed towards each other by their convexity and which are separated by the partition wall between them. In the partition wall there is a bore, which is concentric with the spherical inner surface sides, and a bushing or a bearing is placed in the bore to support the pump shaft. The spherical inner surface comprise the inlet channel and the outlet channel, whereas the inlet channels and outlet channels of the two opposite pump sides are connected in such a way, that the pump has one common inlet opening and one common outlet opening. The position of the pistons in two opposite sides of the pump on the axis of the pump shaft is shifted by 90 degrees in relation to one another in order to reduce the pulsation of the pumped medium in the outlet of the pump.

The working chambers with changing volume during rotation of the pump shaft are formed with the help of the rotor placed fixedly on the pump shaft and with a piston moving in relation to the rotor and in relation to the insert block, and which all have the outer spherical surface with an equal radius corresponding to the inner spherical surface, inside which these parts are placed in the assembled state of the pump.

The rotor is a component with the spherical outer surface, which in the working state is immovably placed on the pump shaft. In the outer surface of the rotor there is a symmetrical cylindrical groove, the axis of which is transverse with the axis of the pump shaft and the side faces of the groove are transverse with the cylindrical bottom of the groove. Through the centre point of the diameter of the spherical outer surface of the rotor there is a bore for the pump shaft, transverse with the axis of symmetry of the cylindrical groove. Additionally the rotor has a back face on the plane transverse with the axis of the bore for the pump shaft. The back face cuts through the bottom of the groove and also through the material of the side faces.

The piston with the spherical outer surface is placed in the cylindrical groove of the rotor in such a way, that it can move in the groove by swinging around the axis of the above mentioned cylindrical groove. The piston of the pump is a C-shaped component with the spherical outer surface when viewed from side. The C-shaped piston has the inner cylindrical surface corresponding to the groove of the rotor and side faces corresponding to the sides of the groove. In the ends of its branches the C-shaped piston has bores for connecting pins for swinging the piston on the rotor with the help of the collar, when the pump shaft is turning. The bores for the pins are coaxial with each other and the axis of the pins runs through the centre point of the diameter of the spherical outer surface of the piston, which in turn in the working state coincides with the centre point of the diameter of the outer spherical surface of the rotor. The C-shaped piston has a through cutout. The cutout (slot opening) is formed in such a way, that on both sides of the cylindrical groove of the rotor there is left material in the form of arches, said arches connecting end parts of the branches with the bores for connecting pins of the C-shaped piston. In the assembled state in that slot an insert block is placed, cylindrical back side of which is placed against the bottom of the groove of the rotor and the spherical outer surface of the insert block corresponds to the outer surfaces of the other components, that is that of the piston and of the rotor. In the assembled state of the pump the outer spherical surfaces of the piston, the rotor and the insert block with an equal radius form a continuation to each other. The insert block is a rectangular component when viewed from top, having a centre bore for the pump shaft. The width of the insert block corresponds to the width of the cutout (slot) so, that while operating the insert block can move in that cutout (slot), however ensuring sufficient tightness for pumping fluid medium.

In the assembled state of the pump the piston is placed on the cylindrical groove on the rotor and the insert block in turn is placed in the cutout of the piston. The chambers with changing volume are formed one on each side of the insert block in the piston cutout, when in the working state by turning of the pump shaft, the piston swings back and forth in the cylindrical groove of the rotor.

In order to make the piston swing back and forth on the rotor, while the pump shaft is turning in the operational state of the pump, the C-shaped piston with the connecting pins in the bores in the ends of its branches is linked with the collar, whereas the plane of the collar is at an angle to the axis of the pump shaft. In the assembled state of the pump the centre point of the collar coincides with the centre points of the diameters of the spherical outer surfaces of the rotor and the piston, which in turn are all placed on the axis of the pump shaft. The inner surface of the collar is spherical, corresponding to the spherical outer surfaces of the rotor and the piston.

The rotor, the piston, the insert block and the collar are closed in the housing by the cover, whereas the cover is provided with an opening, seals and bearings for the pump shaft. Two concave spherical inner surfaces with the common axis comprise a groove for the collar to move the piston. From the ends of the pump shaft one side of that groove is formed by the pump cover. The adjoining surface of the cover with the housing of the pump is at the same angle to the axis of the pump shaft as the angle of the sides of the collar to the axis of the pump shaft. The corresponding adjoining surface of the cover of the other side of the pump is at the same angle to the axis of the pump shaft as the first cover, but in the opposite direction in relation to the first side of the pump. The collar can rotate in the groove freely.

Brief description of the drawings

The invention will now be described by way of an example with reference to the accompanying drawings. In the drawings the pump and its components are for the sake of clarity illustrated in a simplified manner, without any details, which are not necessary to explain the working principle of the pump.

FIG 1 is a schematic exploded view in axonometric projection of the two sided positive displacement twin pump with the piston units according to the invention.

FIG 2 is a cross section according to pump of FIG 1.

FIG 3 is a cross section according to pump of FIG 2 in a position, when the pump shaft has turned by 90 degrees.

FIG 4 is an axial horizontal cross section through the axis of the pump housing according to pump of FIG 1. FIG 5 is an axial vertical cross section through the axis of the pump housing according to pump of FIG 1.

In FIGS 6A, 6B and 6C are representations of a collar, correspondingly in front view, in sectional view and in axonometric projection, with the help of which the piston is swiveled back and forth on the rotor when the pump shaft is turning in the operating pump.

In FIGS 7A, 7B and 7C are representations of a rotor with the spherical outer surface, correspondingly in front view, in sectional view and in axonometric projection, when the outer surface is provided with a cylindrical groove, the axis of which is transverse to the axis of the pump shaft and the side faces of which are transverse to the bottom of the cylindrical groove.

In FIGS 8A, 8B and 8C are representations of a C-shaped piston with the spherical outer surface, correspondingly in front view, in sectional view and in axonometric projection,

In FIGS 9A, 9B and 9C are representations of an insert block intended to be placed in the slot of the C-shaped piston, correspondingly in front view, in sectional view and in axonometric projection.

Detailed description of the invention

As in the beginning of this description it was mentioned, the present invention relates to a piston unit for a rotary pump, which has one common intake channel 18 on the suction side and one common outlet channel 19 on the compression side of the pump (FIGS 2 and 3), and which is intended for pumping fluid medium. It is clear for the person skilled in the art, that the same piston unit can be utilized both in the single and in the twin pump. Since in the preferred embodiments the piston unit according to the present invention is used in the rotary pump having two sides, as it can be seen from FIG 1 , the detailed example of the embodiment is described on the basis of the rotary twin pump having two identical sides. The piston unit (rotor 4, piston 3, insert block 8, collar 2, pins 5) of the rotary pump according to the embodiment of the present invention is placed in the pump housing of the rotary pump with two sides, whereas the housing 1 (FIGS 1 , 4 and 5) comprises two concave spherical inner surfaces 20', 20" on the common axis,

5 which are directed towards each other by their convexity and which have between them a partition wall 21 , separating two sides of the twin pump. In the partition wall 21 there is a bore 22 concentric to the spherical inner surfaces 20', 20", comprising a bushing or a bearing (not shown) to support the pump shaft. The spherical inner surfaces 20', 20" both also include one inlet channel 18', 18" each io and one outlet channel 19', 19" each, whereas two opposite sides of the pump have their inlet channels 18', 18" and outlet channels 19', 19" connected in a way, that the pump has one common inlet channel 18 and one common outlet channel 19. The pistons 3 in the opposite sides of the pump are on the pump shaft 6 shifted in relation to one another by 90 degrees (FIGS 2 and 3) in order to is decrease the pulsation of the fluid medium in the outlet channel 19.

The piston unit, which in the assembled state, comprises on the pump shaft 6 a rotor 4, a piston 3, an insert block 8, a collar 2 and pins 5, is closed in to the pump housing 1 by the cover 7. The cover 7 includes a bore for the pump shaft 6 and

20 seals and bearings (not shown in the figures). The pump housing 1 includes two concave spherical inner surfaces 20', 20" on the common axis. These inner surfaces 20', 20" are directed towards each other by their convexity and they are separated by the partition wall 21 between them, separating also the two separate sides of the twin pump. The spherical inner surfaces 20', 20" both include a groove

25 23 for the collar 2 in order to swivel the piston 3 (FIGS 2 to 5).

From the ends of the pump shaft 6 one side of that groove is formed by the pump cover 7. The adjoining surface of the cover 7 with the housing 1 of the pump is at an angle to the axis of the pump shaft 6, therefore the collar 2 is also at an angle 30 to the axis of the pump shaft 6. The corresponding adjoining surface of the cover 7 of the other side of the pump is at the same angle to the axis of the pump shaft 6 as the first cover, but in the opposite direction in relation to the first side of the pump. The collars 2 can rotate in the grooves 23 freely. In FIGS 1 to 5 the pump housing 1 and the covers 7 are depicted schematically and in a simplified manner, only structural elements essential for the functioning of the pump are shown in more detail. Therefore only the position of the spherical inner surfaces 20', 20", the location of the inlet and the outlet channels 18', 18", 19', 19" (with the arrows showing the flow direction), the partition wall 21 and the grooves 23 for the collars 2 are shown in the housing 1. For better clarity of the drawings all the fixing bolts, as well as the openings for connecting the housing 1 with the covers 7, and the seals and the bearings for the pump shaft 6 in the partition wall 21 and the covers 7 are not shown, as their specific embodiment would be clear to the person skilled in the art. In the actual embodiment the housing and the covers may by manufactured as castings.

It would be clear to the person skilled in the art, that arrows at the corresponding inlet and outlet channels 18', 18", 19', 19" show their common inlet channel 18 and common outlet channel 19 in a situation corresponding to the direction of rotation of the pump shaft in FIGS 2 and 3. Since this pump is bidirectional (reversible), in case the pump shaft rotates in the opposite direction, the inlet and outlet channels interchange respectively, i.e. pumping occurs in the opposite direction to the arrows in FIG 2.

The following description describes individually the components, that form a piston unit.

The rotor 4 of the pump is a component with the spherical outer surface 24, which in the working state is immovably placed on the pump shaft 6 (FIGS 7A to 7C). In the rotor 4 there is a through bore 25 for the pump shaft 6, where the axis of the bore 25 goes through the centre point of the spherical outer surface 24 of the rotor 4. In the outer surface 24 of the rotor 4 there is a symmetrical cylindrical groove 10, the axis of which is transverse with the axis of the bore 25 made for the pump shaft 6. The axis of the cylindrical groove 10 (its bottom) goes through the centre point of the spherical outer surface 24 of the rotor 4. The side faces 14', 14" of the groove 10 are transverse with the cylindrical bottom of the groove 10 and symmetrical to the axis of the bore 25. The rotor 4 has a back face 12 on a plane transverse with the axis of the bore 25 for the pump shaft 6. The back face 12 cuts through the bottom of the groove 10 of the rotor 4 and also through the material of the side faces 14', 14". This back face 12 is necessary for the assembly of the rotor 4, the piston 3 and the collar 2.

In side view of the piston 3 of the pump (FIGS 8A to 8C) is generally a C-shaped component with the spherical outer surface 26. When viewed from side, the piston 3 has the inner cylindrical surface 13 corresponding to the bottom of the groove 10 of the rotor 4 and the side faces 15', 15" corresponding to the sides 14', 14" of the groove 10 by their width. Thus the width of the piston 3 corresponds to the width of the cylindrical groove 10 of the rotor 4. In the ends of its branches the C-shaped piston 3 has bores 16 for the pins 5 to swing the piston 3 on the rotor 4 with the help of the collar 2, when the pump shaft 6 is turning.

The bores 16 for the pins 5 are coaxial with each other and the axis of the pins 5 runs through the centre point of the diameter of the spherical outer surface 26 of the piston 3. When the piston 3 is placed in the groove 10 of the rotor 4, the centre point of the diameter of the spherical outer surface 26 of the piston 3 coincides with the centre point of the diameter of the spherical outer surface 24 of the rotor 4. The spherical outer surfaces 24 and 26 of the piston 3 and the rotor 4 are equal in diameter and in turn they correspond to the spherical inner surfaces 20', 20" of the housing 1.

In the C-shaped piston 3 there is a through cutout 11 , which is made in such a way, that on both sides of the side faces 14', 14" of the cylindrical groove 10 of the rotor 4 there is left material in the form of arches 17, whereas these arches connect parts with the bores 16 in the ends of the branches of the piston 3. In the operational state these bores 16 are intended for the pins 5 to link the piston 3 with the collar 2.

In the assembled state of the piston unit in the cutout 11 of the C-shaped piston 3 an insert block 8 is placed, the width of which corresponds to the width of the cutout 11. The insert block 8 is a rectangular component when viewed from top having a centre bore for the pump shaft 6 (FIGS 9A to 9C). The width of the insert block 8 corresponds to the width of the cutout 11 (slot) so, that while operating the insert block 8 can move in the cutout 11. The length of the insert block 8 is smaller than the length of the cutout 11 , i.e. the transverse dimension of the insert block 8 is smaller than the length of the cutout 11 so, that insert block 8 can move in the cutout 11. The back side 27 of the insert block 8 is the cylindrical concave surface corresponding to the cylindrical bottom of the groove 10 of the rotor 4.

The outer surface 28 of the insert block 8 is the spherical surface corresponding to the outer surfaces of the piston 3 and the rotor 4, i.e. the radius of the spherical outer surface 28 of the insert block 8 corresponds to the radii of the outer surfaces 26, 24 of the piston 3 and the rotor 4.

The collar 2 (FIGS 6A to 6C) is a component having the spherical inner surface. The spherical inner surface of the collar 2 corresponds to the diameters of the outer surfaces 26, 24 of the piston 3 and the rotor 4. In the collar 2 there are in diametrically opposite positions two through bores 29 coaxial with each other. The axis of the bores 29 runs through the centre point of the spherical inner surface of the collar 2. The bores 29 are intended for the pins 5, which are used to link the piston 3 with the collar 2. The width of the collar 2 corresponds to the width of the groove 23 in the housing 1. The outer surface of the collar 2 corresponds to the bottom surface of the groove 23 in the housing 1.

As mentioned above, the piston unit is formed by the rotor 4 placed immovably on the pump shaft 6, by the piston 3, which in turn is placed in the groove 10 of the rotor 4, by the insert block 8, which in turn is placed in the cutout 11 of the piston 3, by the collar 2, which is linked movably with the piston 3 by the pins 5, and which are all closed by the cover 7 in the housing 1.

The piston 3 is intended to be placed together with the insert block 8 into the cylindrical groove 10 of the rotor 4 so, that the piston 3 in the groove 10 can turn around the axis of the cylindrical groove 10. The outer spherical surface 26 of the piston 3 forms continuation to the spherical outer surface 24 of the rotor 4.

With the help of the piston 3, placed in the groove 10 of the rotor 4, on both sides of the insert block 8 placed on the pump shaft 6, where in turn the insert block 8 is placed in the cutout 11 of the piston 3, is formed one working chamber A, B with changing volume, whereas the outer wall of the working chamber is formed by, in the assembled state of the pump, the spherical concave surface 20', 20" of the pump housing 1 , whereas that inner surface includes the inlet channel 18', 18" and the outlet channel 19', 19", which in FIG 2 are indicated by the arrows showing also the flow direction.

In the assembled pump by the rotation of the pump shaft 6, the piston 3 on the rotor 4 is put in motion back and forth by the collar 2. In the assembled pump the centre point of the collar 2 runs through the axis of the pump shaft 6. Since the collar 2 is placed in the groove 23 of the pump housing 1 , the collar 2 is at an angle to the axis of the pump shaft 6. The collar 2 is linked with coaxial pins 5 in diametrically opposite positions in relation to the rotor 4 with the piston 3.

The rotor 4 forces the piston 3 to turn along with the turning of the pump shaft 6. Since the C-shaped piston 3 is linked at the ends of its branches with the pins 5 to the collar 2, the collar 2 forces the piston 3 to turn in the cylindrical groove 10 of the rotor 4, when the pump shaft 6 is turning. As a result the volume of the working chambers A, B on the opposite sides of the insert block 8 changes as the pump shaft 6 revolves.

The present invention is not limited by the embodiments in the drawings and examples given in the specification above, but within the scope of the invention specified in claims other embodiments are possible.

Claims

1. A piston unit of a rotary pump, which in the concave spherical inner surface (20', 20") of the pump housing (1 ) comprises:

a rotor (4), which is immovably placed on the pump shaft (6), where the centre point of the spherical outer surface of the rotor is located on the axis of the pump shaft (6);

- a piston (3) placed on the rotor (4), which can swivel on the rotor (4) around an axis transverse to the axis of the pump shaft (6), whereby with the piston (3) on the rotor (4) one working chamber (A, B) with changing volume on either side of the axis of the pump shaft (6) is formed;

- a collar (2) to swivel the piston (3) on the rotor (4), when the pump shaft (6) is revolving, whereas the axis of the pump shaft (6) runs through the centre point of the collar (2) and the said collar is at an angle to the said axis of the pump shaft (6), and the collar is linked with the piston (3) by the coaxial pins (5) one on each side of the rotor (4) and the collar (2), the axis of the coaxial pins (5) running through the axis of the pump shaft (6);

characterized in that, the working chambers (A, B) with changing volume by the revolving of the pump shaft (6) are formed by an insert block (8), which is placed in a cutout (11 ) of the piston (3) on the axis of the pump shaft (6), and by the piston (3) placed in the groove (10) of the rotor (4), whereas all these parts have the spherical outer surface (24, 26, 28) with the same radius corresponding to the concave spherical inner surface (20', 20") of the pump housing forming the outer wall of the working chambers (A, B).

2. A piston unit of a rotary pump according to claim 1 , characterized in that, the rotor (4) of the pump is a component with the spherical outer surface (24) having a through bore (25) for the pump shaft (6); in the outer surface of the rotor (4) is a cylindrical groove (10), the axis of which is transverse with the axis of the bore (25) for the pump shaft (6) and the side faces (14', 14") of which are transverse with the cylindrical bottom of the groove (10) and are symmetric with the axis of the bore (25) for the pump shaft (6); and the rotor (4) has a back face (12) on the plane transverse with the axis of the bore (25) for the pump shaft (6), whereas the back face (12) cuts through the bottom of the groove (10) and also through the material of the side faces (14', 14").

3. A piston unit of a rotary pump according to claim 1 , characterized in that, the piston (3) of the pump is a C-shaped component with the spherical outer surface (26) having the inner cylindrical surface (13) corresponding to the groove (10) of the rotor (4) and the side faces (15', 15") corresponding to the width of the groove (10) of the rotor (4);

C-shaped piston has bores (16) for connecting pins (5) movably with the collar (2) in the ends of its branches; the bores (16) for the pins (5) are coaxial with each other and the axis of the pins (5) runs through the centre point of the diameter of the spherical outer surface (26) of the piston (3); and - C-shaped piston (3) has a cutout (11 ) between the side faces (15', 15"), which is symmetrical with the branches of the piston (3).

4. A piston unit of a rotary pump according to claim 1 , characterized in that, the insert block (8) is a rectangular component when viewed from top, having a centre bore for the pump shaft (6); the width of the insert block (8) corresponds to the width of the cutout (11 ) in the piston (3) and the cross dimension of the insert block (8) is smaller than the length of the cutout (11 ) to enable it to move in the cutout (11 ); back side (27) of the insert block (8) is the cylindrical concave surface corresponding to the bottom of the groove (10) of the rotor (4) and the radius of the spherical outer surface (28) of the insert block (8) corresponds to the radii of the outer surfaces (26, 24) of the piston (3) and the rotor (4).