AU617002B2

AU617002B2 - Improvements relating to gerotor pumps

Info

Publication number: AU617002B2
Application number: AU41287/89A
Authority: AU
Inventors: Steve Hodge
Original assignee: Concentric Pumps Ltd
Current assignee: Concentric Pumps Ltd
Priority date: 1988-09-28
Filing date: 1989-09-12
Publication date: 1991-11-14
Anticipated expiration: 2009-09-12
Also published as: AU4128789A; IN176246B; NZ230719A; DE68908826T2; EP0361716B1; IE893087L; FI894603A; PT91814B; JPH02185682A; DK471889A; DE68908826D1; DK471889D0; BR8904894A; FI98949C; PT91814A; DK172577B1; EP0361716A2; FI894603A0; FI98949B; AR247277A1

Description

BOOZ21.6 l/9~ 12/09/ 0 1 1

TO:

If k? w The Commissioner of Patents, COMMONWEALTH OF AUSTRALIA.

00 00; moos 1 r 1-:111- i\ i i: :1:l~_i;1-~~~llrPI P 617002 COMMONWEALTH OF AUSTRALIA Patents Act 1952 Name of Applicant s of Applicant: Address of Applicant: Actua.l f1veftor CONCENTRIC PUMPS LIMITED Unit 10, Gravelly Industrial Park, Erdington, Birmingham B24 8HW, United Kingdom STEVE HODGE GRANT ADAMS COMPANY, Patent Trade Mark Attorneys, Level 9, National Mutual Centre, 144 Edward Street, BRISBANE. QUEENSLAND. 4000

AUSTRALIA.

t 4 *4 Address for Service '1 ,i f I t I COMPLETE SPECIFICATION FOR THE INVENTION ENTITLED: "IMPROVEMENTS RELATING TO GEROTOR PUMPS" The following statement is a full description of the invention including the best method of performing it known to us.

I

K j :i 4: ut appucant Is tne assignee s.ala invention from .the said inventor I. 4. The basic application referred to in paragraph 2 of this Declaration fes the first application s made in a Convention country in respect of the invention the subject of the application.

DECLARED at. Birmingham, England, this d September 89.

o f e t i C 2 IMPROVEMENTS RELATING TO GEROTOR PUMPS This invention relates to gerotor pumps comprising a male lobed rotor meshed internally of a female lobed annulus. The annulus has more lobesusually one more than the rotor, and their axes are eccentric. On one side of a plane containing the axes, the chambers bounded by the respective lobes open to an inlet, and on the other side of that plane they open to an outlet. Relative rotation causes said chambers to process about the axes and so vary in size thus inducing flow into the chambers on the inlet side and expelling it out on the outlet side. Such pumps are herein called o: "of the kind referred to".

Known pumps of this kind have the male rotor 15 fast, for example, keyed to a drive shaft which is essentially journalled over an axially extending zone, for example in the pump casing wall, possibly even at Stwo axial locations, one on either side of the meshed parts. The shaft is also fast with a drive pulley, sprocket or gear (collectively called "gear") at a further location. These factors dictate a certain axial length to the shaft apart from that necessary for the S' required volumetric displacement.

The object of the invention is to provide improvements and particularly to enable shorter axial length to be provided.

According to the invention, a gerotor pump i comprising a body, a male lobed rotor meshed internally of a female lobed annulus mounted on an eccentric axis with respect to the rotor, said annulus being journalled in the body, and a drive gear or sprocket for causing i rotation of the gerotor set, characterised in that a stationary fixed shaft is provided in the body, said shaft extending axially through the rotor which is i~ r~f Li 1 3 concentric therewith, a bush on the shaft, said gear or sprocket being journalled on said bush, and a drive connection made between the gear or sprocket and the rotor internally of the rotor and within the axial dimension of the annulus and rotor.

If the shaft is, for example, a force-fit in the body, the lei'gth of the shaft necessary for body engagement is substantially less than what is necessary for spaced bearings carrying a cantilevered shaft, or less than what is necessary for two axially spaced sets of bearings in other designs. However, it might also be o possible to make the shaft and body as a common one piece article for example as a casting when the notional length necessary to connect the shaft and body is even less.

Where drive is taken from the gear to the rotor directly, the gear may be journalled directly on the shaft and the rotor carried by the gear.

^,'Various embodiments of the invention are more 20 particularly described with reference to the accompanying drawings, wherein: Figure 1 is a sectional elevation of a first i CS embodiment; Figure 2 is a fragmentary and elevation of the same; and Figure 3 is a view similar to Figure 1 shcwing j a second embodiment.

Turning first to Figures 1 and 2, a pump body is provided with one or more inlet passages 12 K 30 opening through the side wall (not shown) to the cavity housing the annulus 14 and rotor 16. The outlet passage opens from that cavity. It will be appreciated that both inlet and outlet may open generally radially or f tangentially from the cavity or through one or other II side wall, or a combination of these according to IZ

I

L'-0 i -'p 4 requirements.

Shaft 18 is fast in the body, for example being a press-fit. In Figure 1, it is bushed at 20-22 to journal the rotor 16 and the drive gear 24 respectively. A passage system 30-32 shown in dotted line communicates with port 34 to allow lubrication of the bushes.

The drive gear (or sprocket 24) is provided with axially extending dogs 28 (see Figure 2) which mesh with like dogs 26 in the rotor 16 so that the gear and rotor are directly dogged together for drive between then. Hence, the gear drives the rotor which drives the annulus at a different speed for the usual gerotor pumping action.

Turning now to Figure 3, the arrangement is generally similar except that here, the gear 24 has a hub portion 38 extending over the full axial dimension of the rotor 16, so that the rotor may be considered to be indirectly journalled on the shaft. The hub and rotor are keyed or splined together at 46 for direct drive between them.

C i i; C

Claims

1. A gerotor pump comprising a body, a male lobed rotor meshed internally of a female lobed annulus mounted on an eccentric axis with respect to the rotor, said annulus being journalled in the body, and a drive gear or sprocket for causing rotation of the gerotor set, characterised in that a stationary fixed shaft is provided in the body, said shaft extending axially through the rotor which is concentric therewith, a bush on the shaft, said gear or sprocket being journalled on said bush, and a drive connection made between the gear ,r <or sprocket and the rotor internally of the rotor and within the axial dimension of the annulus and rotor.

2. A pump as claimed in Claim 1 wherein the rotor is journalled on another bush on the said shaft adjacent le. said bush which journals the gear or sprocket., and said gear or sprocket has dogs projecting axially into the rotor for said'drive connection.

3. A pump as claimed in Claim 1 wherein the gear 20 or sprocket has a tubular extension which is journalled on said bush, and the tubular extension extends into the rotor, and the rotor and extension are keyed or splined V together for said drive connection. S4. A pump as claimed in Claim 1 wherein the shaft is a force fit in the body. A pump as claimed in Claim 1 wherein the shaft is unitary with the body. described with reference to FIGS 1 and 2; or FIG 3; of the accompanying drawings. DATED this thirty-first day of July 1991. CONCENTRIC PUMPS LIMITED, By its Patent Attorneys GRANT ADAMS COMPANY. 17! o LU:~