IL165132A - Pump boot seal - Google Patents

Description

165132/2 Tintwtfy OWN Boot seal for rotary pump Carmeli Adahan C. 171370 FIELD OF THE INVENTION The present invention relates generally to pumps and more particularly, to vane pumps used for pumping of fluids in the chemical, medical and food industries, where a perfect seal is required for preventing leakage of pumped media, around the input shaft. It also relates particularly to rotary vane pump described in Israeli Patent Number 160096 filed on January 28, 2004.

BACKGROUND OF THE INVENTION In rotary fluid pumps the pump rotor is generally rotated by an input shaft, which is driven by an electric motor. The pump rotor is generally immersed in the fluid it is pumping, and the shaft driving the pump , rotor is generally sealed by a seal,^such as an 0-Ring._ AU pump shaft seals leak, PJie-jnore .than others, and in critical applications, where leakage cannot be tolerated the pump rotor is driven by magnetic forces through a barrier, such that the pumped media is totally isolated.

UK patent 926,495 teaches the use of a bellows to allow driving of the pump rotor, yet maintaining a complete barrier between the driving shaft and the pumped media. The bellows seal is deficient, since it can collapse if subjected to a high pressure differential. If however it is rigid enough to sustain a high pressure differential, it becomes stiff and thus requires high force to allow orbital movement of the shaft, and as such it is subjected to excessive load and fatigue. A long bellows seal will deflect with low force, but will require a long shaft to go through it and transmit the torque to the pump rotor. Such long shaft is impractical, as it will deflect too much under high loads. 01713700\4-05 SUMMARY OF THE INVENTION In accordance with one aspect of the present invention, there is provided a rotary pump boot seal, which is made of flexible material, such as rubber, allowing free orbital movement of the pump shaft, yet maintaining a complete seal / barrier between the pumped media and the outside of the pump. When subjected to pressure differential, the boot will inflate in one direction, withstanding the pressure differential. When the pressure on the boot is reversed, inner support members prevent its collapse, allowing it to continue functioning fully as a seal, with little resistance to pump shaft orbital movement.

The boot can be filled with a lubricant, such as grease, which will reduce boot wear when it rubs against the inner support members.

The boot can be configured to inflate inwards or outwards, depending on the expectant pressure differential of the application. rotary shaft is replaced with a crank shaft, which transmits the torque, by performing orbital movement within the boot seal. The orbital movement allows for the boot seal to be braced on both of its ends, maintaining a complete seal, without the need to have any relative movement between the boot seal and the sealed elements, as is^the case with conventional pump seals.

Other objects and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawing and appended claims.

BRIEF DESCRIPTION OF THE DRAWING In order to understand the invention and its application, a preferred embodiment will now be described, by way of a non-limiting example only, with reference to the accompanying drawings, in which: 01452556U1-01 Fig. 1 is a schematic cross sectional view of a vane pump in accordance with a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION With reference to Fig. 1, there is shown a vane pump 10 in accordance with a preferred embodiment of the present invention. The vane pump 10 comprises a pump unit 12 and a drive unit 14 detachably attached to each other.

The pump unit 12 includes a housing 16 with a cylindrical cavity, and a cylindrical rotor 20 disposed eccentrically in the cavity of the housing so as to define a pump chamber 18. The housing 16 has an inlet port (not shown) and an outlet port 26 communicating with the pump chamber 18.

Rotor 20 is disposed in the housing cavity in sliding contact with the cover 38 and the wall 37, centered and driven by crank shaft 21. Crank shaft 21 orbits when Drive unit 14 drive shaft 22 rotates. Bearings 23 allow crank shaft 21 to orbit without rotating around its axis, thus preventing relative movement between it and rotor 20.

. A resilient boot 28 provides a complete seal between housing wall 37 and rotor 20. Boot 28 is fastened to rotor 20, by means of retainer 25. It is also fastened to housing wall 37 by means of retainer 27. Thus, crank shaft 21 can impart orbital movement to rotor 20, with boot 28 maintaining complete isolation between pump chamber 18, crank shaft 21 and cavity 30 within which it orbits.

The balloon shape of boot 28, combined with its flexibility, allows crank shaft 21 to impart orbital movement to rotor 20, without friction or resistance.

Should the pressure in pump chamber 18 be lower than the pressure witriin cavity 30, the boot 28 will inflate, moving away from retainers 25 and 27, yet mamtaining complete isolation between pump chamber 18 and cavity 30.

Should pressure in pump chamber 18 be higher than the pressure within cavity 30, the boot 28 will be forced against retainers 25 and 27, which will support it, yet providing free orbital movement for crank shaft 21, and maintaining a complete seal between pump chamber 18 and cavity 30. 01713700\4-05 Unlike other sealing arrangements, and a bellow in particular, the proposed construction allows for the entire sealing arrangement to be placed within a recess in rotor 20, not adding length to the drive, which is preferably short.

While a particular embodiment of the invention is shown and described, numerous variations and alternate embodiments will occur to those skilled in the art. Accordingly, it is intended that the invention be limited only in terms of the appended claims. 01452556\11-01 ABSTRACT A rotary pump comprising a drive unit including an eccentric drive member, and a pump unit including a housing cylindrical rotor disposed eccentrically in the cavity. The rotor is engaged to the eccentric drive by means of a crank'whi'ch rotates it. A boot seal is affixed to the pump rotor on one side and to the pump housing on its other end, providing for free movement of the crank, yet mamtaining a complete seal between the pump rotor and its housing. The boot seal is prevented from collapsing when pressure is applied on it, by rigid support members disposed within it, which do not hinder the orbital movement of the crank and the driven pump rotor.

Claims (6)

165132/4 - 5 - CLAIMS:

1. A boot seal for a rotary pump comprising a drive unit including an eccentric drive member, and a pump unit including an eccentrically driven member disposed within a pump housing and being engaged to said eccentric drive member so as to impart an orbital motion to the eccentrically driven member, the boot seal being compliant, and configured for being affixed on one of its ends to the eccentrically driven member and on its other end to the pump housing, such that the eccentric drive member can freely drive the eccentrically driven member, by a crank orbiting within the boot seal, transmitting drive torque to the eccentrically driven member, without any rotary movement between said boot seal and the eccentrically driven member or the pump housing when affixed thereto, wherein said boot seal is prevented from moving inward or collapsing, when outside pressure is applied on it, by means of rigid support members which are placed within it, yet providing for free orbital movement of the eccentric crank within the boot seal and rendering the boot seal equally effective in sealing when pressure is applied inwards or outwards, and wherein said boot is made of compliant material such as rubber.

2. ■2. The rotary pump boot seal according to claim 1, wherein said boot is lubricated internally by a substance such as grease, allowing free sliding of the support members disposed within it.

3. . 3. The rotary pump boot seal according to any one of claims 1 to 2, wherein said boot is positioned within the pump's driven member, allowing for minimal pump width.

4. A rotary pump, comprising a drive unit including an eccentric drive member, and a pump unit including an eccentrically driven member disposed within said pump unit and being engaged to said eccentric drive member so as to impart rotary motion to the eccentrically driven member, and further comprising said boot seal as defined in any one of claims 1 to 3. 01713700\4-08 165132/2

5. A rotary pump boot seal, substantially as described herein with reference to the appended drawings.

6. A rotary pump, substantially as described herein with reference to the appended drawings. For the Applicants, REINHOLD COHN AND PARTNERS 01713700\4-08