GB2197688A

GB2197688A - Rotary vane pumps

Info

Publication number: GB2197688A
Application number: GB08726171A
Authority: GB
Inventors: Hiroshi Sakamaki; Yukio Horikoshi; Kenji Tanzawa
Original assignee: Eagle Industry Co Ltd
Current assignee: Eagle Industry Co Ltd
Priority date: 1986-11-21
Filing date: 1987-11-09
Publication date: 1988-05-25
Anticipated expiration: 2007-11-09
Also published as: IT1211514B; DE3738943A1; KR880006463A; GB8726171D0; JPS63131883A; GB2197688B; IT8767959A0; FR2607196A1

Description

2197688 1 PUMPS The present invention relates to pumps and in particular

to rotary pumps for use for example in a supercharger or a compressor.

It is an object of the present invention to -Drovide ar n improved pump.

In accordance with 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 plate-like vanes movable into and out of a plurality of vane grooves or slots in the form of a depression in said rotor, wherein repeated variations in volumes of working spaces between the vanes resulting from rotations of the rotor and the vanes are utilized to suck a fluid from one side and discharge it towards the other side, characterised in that retainers or bearings coaxl.al with the inner peripheral spaces are rotatably disposed internally of the end wall of the housing, the retainers or bearings engaging with the vanes to define the appearance of the vanes from the vane grooves, and a back pressure regulating groove is guided to a bottom of the vane groove positioned in the back surface of each of the vanes.

According to the present invention, the appearance of the vanes from the vane grooves is not defined by the contact thereof with the innel.

J peripheral surface of the housing but is defined so J that the end edge of the vanes deplcts a fj-xed locus by the engagement of the retainer fitted in the housi.ng and each of the vanes. Therefore, the vanes may be rotated in the state where they are not in contact with the inner surface of the housing; and when the vanes are operated to be projected and retracted, the pressure on the bottom of the vane 2 in the back surface of the vane is groove posi made adjustable so as not to apply an excessjve load to the vanes being projected and retracted.

The vane pump is designed so that the vanes may be rotated in a state spaced from the inner peripheral surface of the housing, and therefore, the lowering of the rotational efficiency and the wear of vanes resulting from the sliding resAstance may be prevented. Also the reduction in the volumetric efficLency due to the increase of heat generation caused by sliding Is avoided; and the back pressure regulating groove is formed re'Latlve to the vane groove bottom so that the back pressure of the groove bottom may be regulated, and therefore the vanes may be operated smoothly without applying an excessive load thereto, and the smooth operation of the whole pump Ls secured.

A vane pumiD embodying the present invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which:

FA.g. 1 is a long-Ltud-,Lna"L section through a fi.rst vane pump embodyLng the present invention; Fig. 2 is a cross-se--t.-'Lon through the pump of Fig. 1; Figs 3 to 5 are --.-oss-se--tions through the pump of Fig. 1 showirLg different forms for a back ng groove; pressure regulati Fig. 6 is a longitudinal section through a second vane pump embodying the present invention; Fig. 7 is a cross-section of a third vane pump embody ng the present invention; and Fig. 8 is a fragmentary cross-section of a previously proposed vane pump.

Fig. 8 shows a previously proposed vane pump having a housing 51 and a rotor 52 inserted epcentrically into an inner cylindrical chamber or space of the housing 51 and rotatably supported by a rotary shaft 53. Plate-like vanes 55a, 55b and 550 are disposed radially retractably in vane slots or grooves 54a, 54b and 54c equally spaced apart-so as to peripherally divide the outer circumferential surface of the rotor 52 into three sections. When the rotor 52 is rotated in the sense as indicated by the arrow X by the rotary shaft 53, the vanes 55a, 55b and 55c are moved radially outwardly by the centrifugal force, and the end edges thereof rotate while making slidable contact with the inner circumferential surface of the housing 51. Since the rotor 52 is eccentric with respect to the housing 51 as previously mentioned, as such rotation occurs, the volumes of the working spaces 56a, 56b and 56c defined by the housing 51, the rotor 52 and the vanes 55a, 55b and 55c are repeatedly enlarged and contracted to allow a fluid taken in from an intake port 57 to be discharged out of an outlet port 58.

However, the vane pump has the problem that since the vanes slidably move along the inner peripheral surface of the housing at high speeds, the lowering of the rotational efficiency due to the sliding resistance between the end edge of each vane and the inner peripheral surface of the housing cannot be avoided. Accordingly the volumetric efficiency of carrier fluid due to the sliding heat is reduced and the vanes expand to produce galling with both the inner surfaces in the radial direction of the housing; and as a consequence considerable wear occurs.

The vane pump shown in Figs. 1 and 2 has a front housing 1 and a rear housing 2, both made of 4 non-ferrous metal such as aluminium. which is light in weLght and has a low coefficient of thermal expansion. The housings are secured together by means of bolts 3. A rotor 4 made of iron is eccentrically inserted into an inner cylindrical space or chamber 5 of the combined housings. The rotor has a shaft 10 which is supported at one end by a ball bearing 7a held by a fixed ring 6 in anti sJ_Lpout fashion in an axial shoulder of the front housing 1 and is supported at the other end by a ball bearing 7b held by a bearing cover 8 in anti-slipout fash.on in an axial shoulder of the rear housing 2.

The shaft 10 supports a drive pulley 9. Plate-like vanes Ila, llb and llc principally made of a carbon material having an excellent slidability are radially movable into and out of vane grooves or slots 12a, 12b and l2c, equiangularly spaced around the rotor to divide the outer circumferential surface of the rotor 4 into three sections. Steel pins 13 project axially from opposite axial ends of each of the vanes lla, llb and 11c. A sleeve bearing made of resin having excellent slidability and abrasion resistance cups each of said pins 13. Rotatably fitted in annular recesses 14a and 14a formed in inner surfaces of end wal"Ls where the front housng 1 and the rear housing 2 face each other and coaxial with the inner cylindrical space 5 within the housing (coax-Lal with an Lnner circumferential surface 1 1 of the front housing 1) are retainer plates 15a and 15a made of non-ferrous metal such as alumLnium and each having an annular race 16. The p.Jns 13 projecting from the espective vanes 1 la, llb and 11c slidably engage the annular races 16 of the retainer plates 15a and 15a.

This engagement defines the radial displacement of the vanes 1 la, 1 lb and 1 lc during rotation so as to 1 ensure a slight clearance between the end edges thereof and the inner circumferential surface 1 1 of the front housing 1. In the inner surface of the end wall of the rear housing 2, an annular back pressure regulating groove 18 is formed coaxially with the shaft 10 on the inside diameter side of the annular recess l4b so that bases 12a', 12b' and l2c' of vane grooves or slots 12a, 12b and 12c face the radially inner ends of the vanes lla, llb and llc and communicate with one another as shown in Fig. 2.

In operation when the shaft 10 and rotor 4 are rotated by the drive force from the pulley 9, the vanes lla, llb and llc also rotate, and the pins 13 and 13 projecting from the vanes lla, llb and llc rotate along the annular races 17 and 17. Since as shown in Fig. 2, the inner circumferential surface 1 of the housLng and the annular race 16 are coax- Lal and since the annular race 16 and the rotor are eccentrica'Lly disposed with respect to one another, the vanes lla, llb and llc slide rad-Lally in and out of the vane grooves 1 2a, 1 2b and 1 2c in the rotor 4. As a result, the volumes of the workLng spaces 5a, 5b and 5c defined between the housings 1, 2, the rotor 4 and the vanes lla, llb and llc repeatedly inc-l-ease and decrease. That is, in Fig. 2, the working space 5a, with the rotation, increases its volume to suCk the fluid from the intake port. As the working space 5c rotates its volume decreases and the fluid is d.ischarged into the outlet port. The work-ing space 5b thus transfers the thus sucked fluid toward the outlet port. In the above- descrLbed operation, the end edges of the vanes 1 lag 1 lb and 1 lc do not make sli.ding contact with the inner cLrcumferential surface 1 1 of the front housing, as previously mentioned, and therefore, the risk of abrasion or high heat ls reduced. The pins 13 are sl.-Ldably rotated while beLng pressed against the outside diameter side by the centrifugal force within the annular race 16 of the retainer plates 15a and 15b but the retaLner plates 15a and 15b follow the pins 13 and rotate since the retainer plates are in the state in which they may be rotated by the presence of the ball bearings 17a and 17b. The relative sliding speed between the pins 13 and the annular races 16 is small, thus minimizing abrasion between the annular races (reta.-Lner plates 15a, 15b) and the pins 13.

The volumes between the bases 1da ? 1 1 and 12c' and their respective vane plates 11a, 11b, 11c repeatedly increase and decrease with the projection and retraction of the vanes 11a, 11b and 11c as the rotor 4 rotates. The volume is a minimum when the vane 1 l a is in its most retracted state as shown in FLg. 2 whereas it is maximum when the vane is in the most projected state. The internal pressure of the volumes at the bases 12a', 12b' and 12cl acts as back pressure on the vanes 1 la, 1 1b and 1 lc and increases and decreases according to the aforesaid volumes to induce the state wherein a serious load -.Ls applied to the pin 13 in engagement WLth the annular race 16. More specifically, as vLewed in Fig. 2, the vane groove base 12b' is in a position in which the volume thereof Lncreases, and the internal pressure of the base 12bl gradually decreases. The vane groove base 12c' WhIch is in the beyond the bottom position is conversely Jin posi. L L L 4 L the process in which the volume thereof decreases, and the internal pressure thereof gradually increases. Where the rotor 4 rotates at high speed, the repeated increase and decrease -In the internal 7 1 pressure applies a serious load to the Pin 13 as a back pressure with respect to the vanes 11a, 11b and 11c. In the worst case, the pin 13 becomes snapped.

A back pressure regulating groove 18 is 'ded so that the internal pressure of the vane prov.1 groove bases 12al, 12bl and 12c' may be regulated. The back pressure regulating groove 18 is annular and coaxial with the rotary shaft 10 in the inner surface of the end wall of the rear housing 2. It provides communication between the vane groove bases 12al, 12bl and 12c'. DurLLng a period of increase and decrease in volumes of the vane groove base 12al, 12bl and 12e' and because the sum of the volumes at three bases 12a', 12bl and 12cl is always approximately equal, the back pressure regulating groove 18 transfers a part of pressure from the base 12cl in the pressure increasing process to the base 12b' in the pressure decreasing process to always balance the aforesald pressure so as not to induce an excessive increase or decrease in pressure to the bases 12al, 12bl and 12cl.

Fig. 3 shows an arrangement wherein the back pressure regulating groove 18 is divided into a pressure decreasing process po.-tion 18a from the top position to the bottom Position, and a pressure 4 ing port-on 18b from the bottom pos-t-lon to increasi L.4. L the top position. The pressure decreasiiig portion 18a communicates with an inlet communication space 19 through a pipe 21 and the pressure inc- leasing portion 18b communicates with an outlet communication space 20 by a pipe 22. This ensures that opposite radial extremities of the vanes 11a, 11b and 11c are subjected to the same pressures. Fig. 4 shows an arrangement wherein the annular back pressure regulating groove 18 and the inlet communication - 8 space 19 are connected through the pipe 21, and Fig. 5-shows an arrangement wherein the back pressure outlet communication regui-ating groove 18 and the space 20 are connected through the pipe 22, whereby the inside and outside of the vanes 11a, 11b and 11c are roughly equalised in pressure to relieve the load applied to the vanes.

In the vane pump shown in Fig. 6 parts similar to those shown in Figs. 1 to 5 are simLar'Ly referenced. As shown in Fig. 6, the vane pump is designed so that retaLner rings 23a and 23b having a si.mpi-e reCtangular section in place of the retainer "'ates 15a and 15b having the annular race -1- the PL L -L 6 L- pump of Fig. 1, are fitted in annular recesses 14a and 1 4b in order to reduce trouble and cost required for manufacturing the retainer rings 20a and 20b of FI.g. 1. The pins 13 projecting from the axial ends of the vanes 11a, 11b and 11c engage the retainer rings 23a and 23b to control the appearance of the vanes from the vane grooves 12a, 12b and 12c and to maintain 'them spaced from the inner Circumferential surface 11 of the housing 1. With this arrangement, J the vanes 1 1 a, 1 1 b and 1 1 c are f reed in a d irection -Ln which they are retracted into the vane grooves 1 2a, 1 2b and 1 2c, and the vanes 1 1 a, 1 1 b and 1 1 c are freely retracted when the pump stops or runs at a low speed, by whiCh movement the vanes undergo an Impact load and are possibLy damaged ea.-j-y. Therefore, bosses 24a and 24b acting as stops are provided on the vanes 11a, 11b and 11c to limit the free movement thereof. These bosses 24a and 24b arranged in the form of an annulus are positioned coaxial with the inner. peripheral space 5 of the housing 1 and moulded Integral with the end walls of the front housing 1 and rear housing 2. In the end surface of the boss 1 24b on the rear housing 2 side are formed back pressure regulating grooves 18, 18a and 18b having a construction as shown in Figs. 3 to 5. The retainer rings 23a and 23b may be replaced by ball bearings.

In the vane pump shown in Fig. 7 stops 25a and 25b projecting parallel to the axis are formed on the outer peripheral ends of retainer plates 15a and 15b to control the appearance of the vanes 11a, 11b and 11c. Cams 26 and 27 rotatably couple the rotor 4 and the retainer plates 15a and 15b between 'the oppos.i.te ends thereof, the cams being disposed three Lly spaced relation. on one side of in number in equal 1.1 the rotor 4. The cams 26 and 27 engage in recesses 32 and 33 formed in equiangularlly spaced relationship in the end of the rotor 4. The cams have first pins 28 and 29 which engage the rotor 4. The pins 28 and 29 are Located at the centre of one face (the inner face) of a circular disk which forms the body of the cam. Each pin 28 and 29 is rotatably mounted on the rotor 4 through a respective ball bearing 34 and 35.

The cams further have second Pins 30 and 31 which engage the retainer plates 15a and 15b. These pins extend axia'Lly from the disk adjacent the -c ,.j.-k,um'Lei-ent-La"L edge of the other face (the outer face) of the rotary disk. These Pins 30 and 31 are rotatably supported by ball bearLLngs 38 and 39 Jin recesses 36 and 37 formed in the retainer plates 15a and 15b. The first pins 28 and 29 and the second pins 30 and 31 are on the circumferences Of Circles of the same diameter but eccentrically located wjth respect to each other by the same degree of ec-centricity as the rotor 4. The retainer plates 15a and 15b are rotated -1n synchronism with the rotor 4 by the cams 26 and 27. This pump also defines the radial displacement of the vanes 11a, 11b and 11c by - 10 the action of the stops 25a and 25b to maintain the vanes Ila, Ilb and lIc spaced from the housing 1. Furthermore the cams 26 and 27 are used to provide a synchronous rotation between the rotor 4 and the retainer plates 15a and 1 5b, thus making it -possible to suppress the loss of torque result.Lng from the rotation. This helps to prevent inconveniences such as wear, and the generation of heat. It is to be noted that Ln the pump, the cams 26 and 27 may be 10 removed to s- :Implify the construction, and in addL Lon, the bosses of Fig. 6 may be added, and means for defining the movement of the vanes lla, llb and 1 lc may be used.

As means for defining the amount of displacement of the vanes lla, llb and 11c, it is contemplated that in addition to the above, the aforesaid cams 26 and 27 are used to engage the vanes Ila, llb and 11c with the retainer plates 15a and 15b for connect.Lon therebetween.

1 1

Claims

CIAIMS

1. A vane pump comprising a rotor rotatably supported in eccentric fashion within an inner chamber of a housing, a plurality of plate-like vanes positioned to project from and retract into a plurality of vane grooves in the rotor when the rotor rotates, to define a plurality of working spaces which vary in volume as the rotor rotates, each acting to suck a fluid from one side of the pump and discharge it from the other side of the pump, a pair of retainers or bearings extending coaxial with the chamber rotatably located, one at each axial end of the chamber, the retainers or bearings being coupled to the vanes to effect the movement of the vanes relative to the vane grooves, and a back pressure regulating groove communicating with the volume in each vane groove located between the radially inner end of each groove and the radially inner edge of each vane.

2. A pump comprising a stator, defining a generally cylindrical chamber, having circumferentially spaced inlet and outlet ports, a rotor mounted in said chamber for rotation about an axis extending parallel to but spaced from the axis of the chamber, the inlet port communicating with the chamber at a point where the gap between the rotor and the housing is progressively enlarging in the direction of rotation of the rotor and the outlet port communicating with the chamber at a point where said gap is progressively reducing in the direction of rotation of the rotor, said rotor having a plurality of circumferentially spaced radially extending slots each accommodating a vane, the displacement of each vane being controlled by cam means, when the rotor rotates along its corresponaing slot to a position adjacent but spaced from the circumferential wall of the chamber, so that the vanes divide the chamber into separate compartments which change in volume as the rotor rotates to create a pump action between the inlet and outlet ports, and means communicating with the volume between the radially inner end of each vane and the corresponding radially inner end of each slot to relieve the pressure therein and thereby reduce the force acting on the cam means.

A pumn according to Claim 2 wherein the communication means comprises an annular groove which provides simultaneous communication between all said volumes.

4. A pump according to Claim 2 wherein the communication means comprises a duct which provides communication between each volume when it passes through a first predetermined region and the outlet port.

5. A pump according to Claim 2 or to Claim 4 wherein the communication means includes a duct which provides communication between each volume when it passes through a second predetermined region and the inlet port.

6. A pump substantially as hereinbefore described with reference to any one of Figs. 1 to

7.

p