Rotary expansible chamber devices – Methods
Reexamination Certificate
1999-09-02
2001-04-24
Vrablik, John J. (Department: 3748)
Rotary expansible chamber devices
Methods
C418S048000, C418S150000, C366S040000
Reexamination Certificate
active
06220837
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to progressing cavity pumps and particularly to such pumps suitable for pumping liquid/solid mixtures having a high proportion of relatively incompressible solids.
2. Description of the Prior Art
In, for example, mining applications it is necessary to pump explosive mixtures having liquid and solid components from a truck carrying bulk supplies of the components to pre-drilled holes in the rock to be quarried or mined. Normally the solids content of the mixture is about 35-40% of the total, the remainder being liquid. It is desirable from a cost point of view to reduce the liquid content so that the mixture is about 50% solids. However, existing progressing cavity pumps have excessive power requirements when pumping mixtures of such high solids content and are prone to entrapment of solid material and stalling. Examples of such pumps have been described in U.S. Pat. No. 4,773,834, U.S. pat. No. 4,591,322, GB 1,542,786 and GB-A2,228,976.
BRIEF SUMMARY OF THE INVENTION
It is an object of the invention to provide a progressing cavity pumps capable of pumping mixtures having a relatively high proportion of entrained solids.
According to the present invention there is provided a progressing cavity pump comprising a stator having a bore therethrough formed with a female, two start, helical gear formation of a given pitch. A cooperating rotor formed with a male, single start, helical gear formation of the same pitch and a drive arrangement for causing the rotor to rotate and orbit relative to the stator are provided. The ratio of the eccentricity, e, of the gear formation of the rotor to its minor diameter, d, is in the range of between 1 to 4.6 and 1 to 5.2 and the ratio of the eccentricity, e, of the gear formation of the rotor to stator lead, p
s
, is in the range of between 1 to 11 and 1 to 15.
Preferably, the ratio of the eccentricity (e) of the rotor gear to its minor diameter (d) is in the range of from 1:4.8 to 1:5.0 and the ratio of the eccentricity (e) of the rotor gear to the stator lead (p
s
) is in the range of from 1:13 to 1:13.6. Ideally the ratio e:d is about 1:4.9 and the ratio e:p
s
, is about 1:13.3.
Pumps according to the present invention are able to pump liquid/solid mixtures with a solids content of about 50% with a reduced power requirement and a reduced risk of entrapment of solid material.
REFERENCES:
patent: 2636834 (1953-04-01), Myers
patent: 3380391 (1968-04-01), John
patent: 3503343 (1970-03-01), Jackel
patent: 4104009 (1978-08-01), Chanton
patent: 4325682 (1982-04-01), Willis
patent: 4591322 (1986-05-01), Ono et al.
patent: 4614146 (1986-09-01), Ross et al.
patent: 5318416 (1994-06-01), Hantschk et al.
patent: 0 381 413 (1990-08-01), None
patent: 2 343 906 (1977-10-01), None
patent: 2 557 642 (1985-07-01), None
Harness & Dickey & Pierce P.L.C.
Mono Pumps Limited
Vrablik John J.
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