GB2197389A

GB2197389A - Rotary vane pumps

Info

Publication number: GB2197389A
Application number: GB08725914A
Authority: GB
Inventors: Hiroshi Sakamaki; Yukio Horikoshi
Original assignee: Eagle Industry Co Ltd
Current assignee: Eagle Industry Co Ltd
Priority date: 1986-11-17
Filing date: 1987-11-05
Publication date: 1988-05-18
Anticipated expiration: 2007-11-05
Also published as: IT1211516B; DE3738484A1; KR880006462A; DE3738484C2; FR2606838A1; GB8725914D0; GB2197389B; IT8767961A0

Description

1 GB2197389A 1

SPECIFICATION

Pumps The present invention relates to pumps and in particular to rotary vane pumps for use, for example, in a supercharger or a compressor.

It is an object of the present invention to provide an improved pump.

According to the present invention there is provided a vane pump comprising a rotor rotatably supported in eccentric fashion in an inner peripheral space of a housing, and a plate-like vanes disposed capable of being projected and retracted into a plurality of vane grooves in the form of a depression in said rotor, wherein repeated variations in volumes of working spaces between the vanes are utilised to suck a fluid from one side and dis- charge it toward the other, characterised in that retainer plates which are coaxial with said inner peripheral spaces are rotatably fitted internally of the end wall of said housing, and said vanes and said retainer plates are con- nected by cams to define an appearance of the vanes from said vane grooves.

According to the present invention, the appearance of the vanes from the vane grooves is not defined by the contact with the inner peripheral surface of the housing but it is 95 defined so that the end edges of the vanes depict a given locus by engagement of the retainer plates fitted in the housing with the vanes through the cams. The vanes can be rotated in a state not in contact with the inner surface of the housing. This has the effect of lowering the rotational efficiency and the wear of the vanes due to the sliding resistance, and reduces the occurrence of such inconveniences as the lowering of the volume efficiency due to the increase in heat generation caused by sliding can also be prevented., A rotary vane pump will now be described, by way of examples, with reference to the accompanying diagrammatic drawings, in 110 which:

Figure 1 is a longitudinal section through a first vane pump embodying the present invention; Figure 2 is an exploded fragmentary perspective view of the vane pump of Fig. 1; Figure 3 is a fragmentary cross-section of the vane pump of Figs. 1 and 2; Figure 4 is a fragmentary cross-section of a second vane pump embodying the present in- vention; Figure 5 is a longitudinal section through a third vane pump embodying the present inven tion; Figure 6 is a longitudinal section through a 125 fourth vane pump embodying the present in vention; Figure 7 is a front view of a retainer plate of the pump of Fig. 6; Figure 8 is a fragmentary cross-section 130 through a previously proposed vane pump.

Fig. 8 shows a previously proposed vane pump having a housing 31, and a rotor 32 inserted eccentrically into an inner cylindrical chamber or space of the housing 31 and rotatably supported by a rotary shaft 33. Plate-like vanes 35a, 35b and 35c are disposed radially retractably in vane slots or grooves 34a, 34b and 34c equally spaced apart so as to periph- erally divide the outer peripheral side of the rotor 32 into three sections. When the rotor 32 is rotated in the sense indicated by the arrow X by the rotational shaft 33, the vanes 35a, 35b and 35c are moved radially outwardly by the centrifugal force, and the end edges thereof rotate while making slidable contact with the inner peripheral surface of the housing 3 1. Since the rotor 32 is eccentric with respect of the housing 31 as previ- ously mentioned, as such rotation occurs, the volumes of the working spaces 36a, 36b and 36c defined by the housing 31, the rotor 32 and the vanes 35a, 35b and 35c are repeatedly enlarged and contracted to allow a fluid taken in from the intake port 37 to be discharged out of an inlet port 38.

However, this vane pump has the problem that since the vanes slidably move along the inner peripheral surface of the housing at high speeds, the rotational efficiency due to the sliding resistance between the end edge of the vanes and the inner peripheral surface of the housing is lowered. Also the volume efficiency of carrier fluid due to the sliding heat cannot be avoided and so the vanes are expanded to produce galling with both inner surfaces in the radial direction of the housing; and considerable wear occurs.

The vane pump shown in Figs. 1 to 3 has a front housing 1 and a rear housing 2, both made of non-ferrous metal such as aluminium which is light in weight and has a low coefficient of thermal expansion. The housings 1 and 2 are secured together by means of bolts. A rotor 4 made of iron is eccentrically located in an inner peripheral space 5 of the combined housing and has a shaft 10 which is supported at one end by a ball bearing 7a held by a fixed ring 6 in anti- slipout fashion in an axial shoulder of the front housing 1 and at the other end by a ball bearing 7b held in a bearing cover 8 in anti-slipout fashion in an axial shoulder of the rear housing 2. The shaft 10 supports a drive pulley 9. Plate-like vanes 11 a, 11 b and 11 c principally made of a carbon material having an excellent slidability are disposed to be radially projected and retracted in vane grooves or slots 12a, 12b and 12c, respectively, which are formed in the form of a depression in an equally spaced apart relationship so as to peripherally divide the outer peripheral side of the rotor 4 into three sections. In annular recesses 13a and 13b formed in inner surfaces of end walls where the front housing 1 and rear housing 2 face 2 each other and coaxial with the inner peripheral space 5 of the housing (coaxial with an inner peripheral surface of the front housing 1), are retainer plates 14a and 14b made of non-ferrous metal such as aluminium rotatably supported by ball bearings 15a and 15b, respectively. The vanes 11 a, 11 b and 11 c are brought into engagement with the retainer plates 14a and 14b through cams 16a, 16b, 16c, 17a, 17b and 17c. The cams 16a, 16b,... 17c fitted in recesses 22a, 22b, 22c, 23a, 23b and 23c equally spaced apart into three sections in the inner surface of the retainer plates 14a and 14b are rotatably provided on the retainer plates 14a and 14b through ball bearings 24a, 24b, 24c, 25a, 25b and 25c, with first pins 18a, 18b, 18c, 19a, 19b and 19c in engagement with the retainer plates 14a and 14b projected around one surface (outer surface) of a circular rotary plate, and are rotatably engaged with engaging recesses 26a, 26b, 26c, 27a, 27b and 27c in which second pins 20a, 20b, 20c, 21a, 21b and 21 c are formed on the side ends of the vanes 11 a, 11 b and 11 c, with second pins 20a, 20b,... 21c in engagement with the vanes 11 a, 11 b and 11 c projected in the vicinity of the peripheral edge of the other surface (inner surface) of said rotary plate. The engaging re- cesses 26a, 26b,... 27c are provided close to the outer ends of the side ends of the vanes 11 a, 11 b and 11 c. As shown in Fig. 3, at the top position in which the vane 1 '1 a is retracted most deeply within the vane groove or slot 12a, the pins 18a, 19a, 20a and 21a of the cams 16a and 17a are laid on the vane 11 a, and the second pins 20a and 2 1 a are positioned close to the other ends of the first pins 18a and 19a.

In operation when the shaft 10 and the rotor 4 are rotated by a drive force transmitted to the pulley 9, the vanes 11 a, 11 b and 11 c also rotate, and the torque is transmitted from the vanes 11 a, 11 b and 11 c to the retainer plates 14a and 14b through the cams 16a, 16b,... 17c. The retainer plates 14a and 14b rotate coaxially with respect to the peripheral surface of the housing, as a consequence of which the cams 16a, 16b,... 17c located in the recesses 22a, 22b,... 23c of the retainer plates 14a and 14b also rotate (revolve) coaxially with respect to the inner peripheral surface of the housing. Since the rotor 4 is eccentrically mounted with respect to the inner peripheral surface of the housing, as previously mentioned, the vane 1 '1 a and the cams 16a and 17a are in vertical alignment in the top position, move out of vertical alignment with rotation and again move into vertical alignment in the bottom position (which is symmetrical with top position through 180' and in which the vane 1 '1 a is moved out of the vane grooves 12a farthest). With this arrangement, the vanes 11 a, 11 b and 11 c con- nected to the retainer plates 14a and 14b GB2197389A 2 through the cams 16a, 16b,... 17c slides radially and repeatedly in and out of the vane grooves 12, 12b and 12c of the rotor 4 with the result that volumes of the working space defined by the housings 1, 2, the rotor 4 and the vanes 11 a, 11 b and 11 c are repeatedly increased and decreased to transfer the fluid from the intake port not shown to output port. In the above-described operation, the appearance of the vanes 11 a, 11 b and 11 c from the vane grooves 12a, 12b and 12c is defined, and the vanes are rotated without making contact with the inner peripheral surface of the housing, thereby eliminating the loss of torque and preventing wear and the generation of heat.

In the pump shown in Fig. 4 the second pins 20a and 21a of cams 16a and 17a superimposed on the vanes 11 a at the top posi- tion are positioned toward the inner ends of the first pins 18a and 19a, the engaging recesses 26a, 26b... 27c formed in the side ends of the vanes 11 a, 11 b and 11 c, respectively, being provided toward the inner ends of said side ends. Other structures are the same as those of the aforementioned first em bodiment, and the description thereof will be omitted with reference numerals merely aff ixed.

In the above-described both embodiments, the locus of the end edges of the vanes 11 a, 11 b and 11 c whose appearance is defined is not always circular, and it is therefore desired that in designing the pump, the dimensions and arrangement of parts are adjusted so that the focus is made close to a circle. However, conversely, the inner peripheral surface of the housing is not made to be circular but adjusted to said locus so that the end edges of the vanes 11 a, 11 b and 11 c and the clearance in the inner peripheral surface of the housing are maintained to be equal to each other over the whole periphery.

The pump shown in Fig. 5 in addition to the features of the pump shown in Figs. 1 to 3 has backup rings 28a and 28b for restraining a deflection of the retainer plates, interposed between the retainer plates and the end wall of the housing. The vanes 11 a, 11 b and 11 c are supported on the retainer plates 14a and 14b by the cams 16a, 16b, 16c, 17a, 17b and 17c. To provide the smooth in and out movement of the vanes 11 a, 11 b and 11 c, the retainer plates 14a and 14b must be firmly supported and smoothly rotated in order not to oscillate the retainer plates 14a and 14b. Practically, however, the ball bearings 15a and 15b oscillate in the thrust direction, and the retainer plates 14a and 14b oscillate due to the pressure distribution within the working space 5 into contact with the end walls of the housings 1 and 2, resulting in a deviation or an inclination of the vanes 11 a, 11 b and 11 c. The present pump takes this into consideration beforehand, and the backup 3 GB2197389A 3 1 rings 28a and 28b are interposed between the retainer plates 14a and 14b and the end walls of the housings 1 and 2 to prevent the oscillation of the retainer plates 14a and 14b. The backup rings 28a and 28b are made of nonlubrication sliding material such as carbon and resin and are fitted in annular grooves positioned partly in the annular recesses 13a and 13b, and the ends thereof are brought into contact with the back of the retainer plates 14a and 14b. In addition, a number of coil springs 29a and 29b are provided as needed to strengthen the supporting force, thus preventing the oscillation of the retainer plates 14a and 14b and so prevent the retainer plates 14 and 14b from contacting the end wall of the housing to indirectly secure the smooth operation of the vanes 11 a, 11 b and 1 1c.

When a dynamical pressure bearing such as a spiral groove or a herringbone groove for example is provided in the contact surface between the retainer plates 14a, 14b and the backup rings 28a, 28b, the sliding resistance is reduced to make the rotation of the retainer plates 14a and 14b smooth.

While the pump of the Figs. 1 to 3 has retainer plates 14a and 14b supported by the bearings 15a-and 15b, the pump of Fig. 6 eliminates the need of the bearings 15a and 15b by causing the retainer plates 14a and 14b to be supported directly on the housings 1 and 2 and providing a dynamical pressure bearing mechanism on the end or peripheral surface of the retainer plates 14a and 14b to 100 reduce the number of parts. This dynamical pressure bearing mechanism is composed of a groove capable of producing dynamical pres sure such as a spiral groove, a Rayleigh step groove or a herringbone groove, for example formed on the end surfaces or peripheral surfaces of the retainer plates 14a and 14b, or a recess or a combination of said groove and said recess to minimise the sliding resistance resulting from rotation of the retainer plates 14a and 14b. Fig. 7 shows, as one example of this dynamical pressure bearing mechanism, a spiral groove 30 provided in the outer end surface of the retainer plates 14a and 14b.

Claims

1. A vane pump having a rotor rotatably supported in an eccentric fashion in an inner chamber of a housing, and a plurality of plate- like vanes disposed to project from and retract into a plurality of radially extending vane grooves in the rotor when the rotor rotates, to define a plurality of working spaces which varies in volume as the rotor rotates, each working space acting to suck a fluid from one side of the pump and to discharge it from the other side of the pump and a pair of retainer plates extending coaxial with said inner chamber rotatably mounted on opposite axial end walls of said housing, and said vanes and said retainer plates being coupled by cams which define the movement of the vanes into and out of said vane grooves.

2. A vane pump according to Claim 1, wherein each said cam comprises a rotary member having a first pin located on one side thereof and extending coaxial with the axis of rotation of the member, into a corresponding opening in the retainer plate, and a second pin located on the opposite side of the rotary member, the second pin being radially spaced from the first pin and extending axially into engagement with a corresponding opening in a corresponding vane.

3. A vane pump according to Claim 2, wherein the opening in each said vane with which the second pin engages is located adjacent the radially outer end of the side of the vane.

4. A vane pump according to Claim 2, wherein the opening in each said vane with which said second pin engages is located adjacent the radially inner end of the side of the vane.

5. A vane pump according to any one of Claims 1 to 4, wherein a backup ring for restraining deflection of each retainer plate, said backup ring being interposed between each retainer plate and the corresponding axial end wall of the housing.

6. A vane pump according to any one of Claims 1 to 5, including a dynamical pressure bearing mechanism provided on the end surface or the peripheral surface of each said retainer plate.

7. A vane pump according to Claim 6, wherein said dynamical pressure bearing mechanism comprises a groove capable of producing dynamical pressure formed on the end or peripheral- surface of each retainer plate, or a recess or a combination of said groove and said recess.

8. A vane pump substantially as hereinbefore described with reference to Figs. 1 to 7 of the accompanying drawings.

Published 1988 at The Patent Office, State House, 66/71 High Holborn, London WC 1 R 4TP. Further copies may be obtained from The Patent Office, Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD. Printed by Burgess & Son (Abingdon) Ltd. Con. 1/87.