GB2197030A - Rotary sliding vane pump - Google Patents

Abstract

A pump for liquid fuels comprises a body 1 defining a cylindrical chamber, a rotor 14 eccentrically mounted in the chamber defining an operating space 7 therebetween and having axial grooves 15 receiving radially extensible vanes 16 which sealingly engage in use the cylindrical surface of the chamber. The chamber is closed at one end by a rear end wall of body and at the other end by a cover 22. A suction space (3, Fig. 2) communicates with that part of the operating space 7 in which underpressure is generated in use, and a delivery space 4 communicates with that part of the operating space 7 in which overpressure is generated in use. The suction and delivery spaces (3), 4 each communicate with both ends of the chamber via respective apertures 8, 31, (11), 12 formed in the rear end wall of the body and the cover. A by-pass overload valve (5) is arranged between the spaces (3), 4. <IMAGE>

Description

SPECIFICATION Displacement vane pump The present invention relates to a displacement vane pump with axial suction and discharge channels in the body and the cover of the pump, particularly for delivery pumps, for discharging liquid fuels and fuel oil from storage tanks.

A plurality of design embodiments of displacement vane pumps is known, which are based on the principle of eccentric mounting of a rotor in a casing defining a cylindrical chamber of the pump body which is closed at one end by a (rear) end wall of the pump casing and at the other (front) end by a removable cover. An operating space of the pump chamber is defined between the rotor and the casing. The rotor is provided with axial grooves, inside which are radially displaceably mounted vanes, which upon rotation of the rotor are pressed by centrifugal force against the inner cylindrical surface of the pump casing, thus constituting in one part of the operating space underpressure and in another part overpressure. Those parts of the operating space are provided with suitably placed channels for the inlet and the discharge of the pumped fluid respectively.

One of the known design embodiments of a displacement vane pump has both the inlet and the outlet channels for the pumped liquid formed in the cylindrical wall of the pump casing. Both the inlet and the outlet channels open directly into the operating space in such manner, that they form an intersection curve of the operating space inner cylindrical surface with the profile surface of the channels.

The disadvantage of such a displacement vane pump is that because its vanes are pressed against the inner cylindrical surface of the casing, which is interrupted by the openings of the inlet and the outlet channel, the vanes become irregularly worn on their radially outer edges. Consequently, the pumped liquid seeps circumferentially, and the self priming ability of the pump is substantially reduced, which should be for the pumping of liquid fuels substantially higher than for water pumps.

A further disadvantage of this pump is the reduction of the displacement vane pump output and the increase of its noisiness.

Furthermore, a displacement vane pump is known, in which the inlet and outlet channels open into the operating space via the end wall of the pump casing, the inner cylindrical surface of the operating space thus remaining integral.

The disadvantage of this arrangement of the displacement vane pump is that coverage of a part of each channel by the end face of the rotor reduces the effective area of the actual inlet and outlet channels which open into the operating space via the end wall of the pump casing. To achieve adequate effective area, a larger more massive pump is required. A further disadvantage of this embodiment is that it results in the rotor being forced against the cover, this causing its excessive wear and frequently also the seizure of the rotor in the contact surface with the casing.

According to the present invention there is disclosed a displacement vane pump for use in pumping liquid fuels comprising a body defining a cylindrical chamber, a rotor eccentrically mounted in the chamber defining an operating space therebetween and having axial grooves receiving radially extensible vanes which sealingly engage in use the cylindrical surface of the chamber, the chamber being closed at one end by a rear end wall of body and at the other end by a cover, an inlet channel defining a suction space communicating with that part of the operating space in which underpressure is generated in use, an outlet channel defining a delivery space communicating with that part of the operating space in which overpressure is generated in use and wherein the inlet and outlet channels each communicate with both ends of the chamber via respective apertures formed in the rear end wall of the body and the cover.

The disadvantages of the prior art mentioned above are overcome by the displacement vane pump according to the present invention, of which the subject matter consists in that the sucking space defined by the inlet channel and the delivering space defined by the outlet channel overlay circumferentially the operative space along its whole length and discharge on the front surface of the body in such manner, that the discharge forms a first shaped opening and a second shaped opening, while in the contact surface of the cover, bearing against the front surface of the body, is formed a first shaped hollow and a second shaped hollow, at the end of which a damping slot is formed. The shaped openings interconnect the operative space of the body with both the sucking space and the delivering space via the shaped hollows of the cover.In the contact surface of the cover, or possibly in the front space of the body, an eccentric groove is situated, inside which a sealing ring is located for the sealing of the operative space, the shaped openings, the shaped hollows and the damping slot. The lower part of the shaped openings is formed by a circle line, of which the centre is coincident with the centre of the operative hollow, and the upper part is formed by a circle line, of which the centre is coincident with the centre of the eccentric groove.

A further advantage of the displacement vane pump according to the present invention consists in that its operation is reliable also at higher speed, and a substantial reduction of its mass is made possible while maintaining all technical parameters. In comparison with other types of displacement vane pumps, its construction is simpler, and thus also its manufacture. A further advantage consists in that the inlet of the pumped liquid into the operative space and the outlet of the pumped liquid from the operative space is performed at both ends of the rotor by means of the annular channels in the pump body, shaped openings and shaped hollows, by which the uniform bypass of the rotor by the pressurised liquid is obtained, thus avoiding seizing of the rotor with the pump cover. Another advantage consists in that by providing a damping slot in the pump cover the noisiness is reduced.By forming a continuous outer cylindrical surface of the operative space, the wear of vanes is reduced and their service life prolonged.

One of the possible embodiments of the displacement vane pump according to the present invention is diagrammatically represented in the accompanying drawings, of which; Fig.1 represents the displacement vane pump in section through plane A-A in Fig.2, Fig.2-a view in the direction of arrow "r" in Fig.4, Fig.3-a section through the parting plane between the cover and the body in the direction of arrows C-C, and Fig.4 a section through the said parting plane in the direction of arrows B-B.

The displacement vane pump according to the present invention consists of a cylindrical body 1 defining a cylindrical chamber within which a rotor 14 is eccentrically mounted A partition 2 Is diagonally formed at one (rear) end of the body and outside of the chamber for the purpose of separating a sucking space 3 from a delivering space 4. In the upper part of the body 1, in the sucking space 3, a bypass valve 5 is located. In the central part of the body 1, a hub is formed, in which sleeve 6 is mounted, in which a shaft 13 carrying a rotor 14 is rotatably deposited. An operating space 7 is formed eccentrically relative to the axis of sleeve 6. The operating space 7 is connected to the sucking space 3 and the delivering space 4 by a first annular channel 8 and a second annular channel 31, respectively which are formed in the rear end 9 of body 1.

The sucking space 3 and the delivering space 4 overlay circumferentially the operating space 7 along Its whole length and define openings on the front surface 10 of body 1 comprising a first shaped opening 11 and a second shaped opening 12. On the shaft 13 is mounted the rotor 14, which is provided with longitudinal grooves 15, in which vanes 15 are radially displaceabiy mounted. On the shaft 13 is fastened a packing ring 1 7 and a flat packing 18. At the end of shaft 13 is fixed a V-belt pulley 19 with a bearing 20, which is fixed in sleeve 21. The sleeve 21 is fastened on a cover 22 which is mounted on body 1 so as to form an end wall of the chamber.

The cover 22 contacts the body in a contact surface 23 and includes a first shaped hollow 24 and a second shaped hollow 25 which connect the sucking space and the delivering space with the underpressure part and overpressure part of the operating space respectively. In the extended narrow part of the second shaped hollow 25, a damping slot 26 is formed for the purpose of removing the noisiness of the displacement vane pump. The damping slot 26 defines a recess in the cover 22 of progressively increasing width and depth In the direction of vane motion to thereby provide a flow path of gradual increasing cross section for pressurised liquid.

Shock effects are thereby reduced with consequent noise reduction. Between the cover 22 and the sleeve 21 is mounted a sealing membrane 27, which is pressed by a spring 28 against the packing ring 17.

The contact surface 23 of the cover 22 and the front surface 10 of the body 1 are sealed by a sealing ring 30, which is mounted in the eccentric groove 29 in body 1. The shaped openings 11, 12 interconnect the operating space 7 of body 1 with the sucking space 3 and the delivering space 4 via the shaped hollows 24, 25 in cover 22. The shaped openings 11, 12 are shaped in such manner, that their lower part is formed by a circle line, of which the centre is conincident with the centre of operative space 7 and their upper part is formed by a circle line, of which the centre is coincident with the centre of the eccentric groove 29.

The displacement vane pump according to the present invetion operates as follows: The V-belt pulley 19 is driven from an electric motor (not represented), and transfers the rotary motion to shaft 13 with rotor 14. By centrifugal force, the vanes 16 are slipped out of the longitudinal grooves 15 of rotor 14, and bear against the cylindrical surface of operative space 7. Due to the extension and reduction of the closed space between vanes 16, underpressure and overpressure is constituted in the operative space 7. The pumped liquid flows into the operative space 7 in two directions, of which one direction goes from sucking space 3 via first annular channel 8 in the rear 9 of body 1, and the second direction goes via first shaped opening 11 and the first shaped hollow 24 of cover 22 at the front of the body. The liquid, which is delivered from the operative space 7, flows also in two directions. One direction of the flow goes via the second annular channel 31 in rear 9 of body 1, and the second direction of the flow goes via damping slot 26, shaped hollow 25, cover 22 and the second shaped opening 12 discharging in the front surface 10 of body 1.

The sealing ring 30 seals simultaneously the shaped openings 11, 12, the shaped hollows 24, 25 and the damping slot 26. The rotating shaft 13 is sealed by means of the friction seal consisting of the sealing membrane 27, packing ring 17 and flat packing 18. Against pressure overloading, the displacement vane pump is secured by means of by-pass valve 5, which interconnects the delivering space 4 and the sucking space 3.

Claims (6)

1. A displacement vane pump for use in pumping liquid fuels comprising a body defining a cylindrical chamber a rotor eccentrically mounted in the chamber defining an operating space-therebetween and having axial grooves receiving radially extenable vanes which sealingly engage in use the cylindrical surface of the chamber, the chamber being closed at one end by a rear end wall of body and at the other end by a cover, an inlet channel defining a suction space communicating with that part of the operating space in which underpressure is generated in use, an outlet channel defining a delivery space communicating with that part of the operating space in which overpressure is generated in use and wherein the inlet and outlet channels each communicate with both ends of the chamber via respective apertures formed in the rear end wall of the body and the cover.

2. A pump is claimed in Claim 1 wherein the pump body and the cover are separably connected at a contact surface defined by a front end surface of the body, first and second shaped openings being formed in the contact surface of the body in communication with the sucking and delivery spaces respectively and first and second shaped hollows being formed in the cover to provide communication between the operatinf space and the first and second openings respectively.

3. A pump as claimed in Claim 2 wherein the second hollow includes a damping slot of progressively increasing cross section in the direction of vane motion.

4. A pump as claimed in Claim 2 or 3 comprising a seal operable between the body and cover and comprising an eccentric groove in one or other of the body and cover and a sealing ring within the groove.

5. A pump as claimed in Claim 4 wherein the lower part of the shaped openings is formed by circle line, of which the centre coincides with the centre of the operating space, and the upper part is formed by a circle line, of which the centre is coincident with the centre of the eccentric groove.

6. A pump substantially as hereinbefore described with reference to and as shown in the accompanying drawings.