Rotary expansible chamber devices – Interengaging rotating members – Like rotary members
Reexamination Certificate
1999-03-30
2001-09-04
Denion, Thomas (Department: 3748)
Rotary expansible chamber devices
Interengaging rotating members
Like rotary members
C029S888021, C277S527000, C277S529000, C277S571000
Reexamination Certificate
active
06283740
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to pumps and, more specifically, to lobe pumps. Still more specifically, the present invention relates to an improved seal disposed between the rotors and shaft, splined inserts or adapters enabling the drive shaft to be coupled to a variety of motor drives and an improved means of adjusting the timing of rotary lobe pumps.
BACKGROUND OF THE INVENTION
Rotary lobe pumps are known. Lobe pumps are ideal for pumping shear-sensitive products because the rotating lobes or rotors do not engage one another. Instead, when a lobe pump is properly timed, the rotors make no contact with each other. Accordingly, shear sensitive fluids may be pumped with minimal shear forces imposed on the fluids by the rotors. Traditionally, rotary lobe pumps have been used in sanitary applications, including food and health care products. The pumping chambers are sealed for sanitary reasons and the drive and driven shafts are supported with bearings disposed outside of the pump chamber.
In some lobe pump designs, the rotors are fixedly mounted onto a shaft which passes through the rotor case. The shaft passes through a sleeve support which, in turn, is connected to the rotor case. Because the shaft rotates within the sleeve support and the outside diameter of the shaft and the inside diameter of the sleeve support are closely matched, the positioning of sealing members between the shaft and sleeve support is not possible. However, the positioning of seals between the sleeve support and the rotor case is feasible. In order to prevent fluid from migrating between the shaft and sleeve support, an effective sealing mechanism must be placed between the sleeve support and an inside surface of the rotor. This is problematic because most sealing mechanisms are designed to seal radially inward. However, in the case of rotary lobe pumps employing a sleeve support through which the shaft passes, the sleeve support is stationary and disposed radially inside of an opposing portion of the rotor. Therefore, there is a need for an improved sealing mechanism or seal assembly for mounting on a stationary sleeve support and extending radially outwardly for sealing in a radially outward direction against an inside surface of a rotating rotor.
Further, rotary lobe pumps are typically designed to be coupled with motors of a variety of types. Because motor drives, such as hydraulic motor drives, different motor drives can require different drive shaft designs for the rotary lobe pump. Accordingly, the pump manufacturer must be able to provide a variety of drive shafts for its pump to enable its pumps to be utilized with a wide variety of drive mechanisms. In order to avoid the expense and inconvenience of providing a number of different drive shafts for each rotary lobe pump, manufacturers need a reliable adapter system to enable a single drive shaft to be coupled to a variety of motor drives.
Another problem associated with the use of rotary lobe pumps is the timing or synchronization of the contra-rotating rotors. As noted above, the timing must be exact so that clearances are maintained to prevent rotor-to-rotor contact. The requirement of precise timing makes the assembly of rotary lobe pumps time consuming and, therefore, expensive. Further, because the timing gears are typically fixedly mounted to the drive and driven shafts, the entire shaft assembly must be rotated during the timing adjustment process. Accordingly, there is a need for an improved timing gear/shaft design which enables either the timing gears or the shafts to be rotated during the timing adjustment instead of current designs which require the entire shaft/timing gear assembly to be rotated. By permitting the operator to rotate only the timing gears, the timing adjustment process could be shortened and therefore manufacturing costs could be reduced.
A need also arises when it is desired to change the timing gears during the working life of the pump. Specifically, it may be desirable to switch from a straight timing gear to a slanted or herringbone type timing gear. Thus, there is a need for a timing gear configuration whereby the timing gears can be easily replaced.
Still another problem that arises with the seals of rotary lobe pumps and other pumps is the difficulty in changing the seals or servicing the seals. Often, the pump must be substantially disassembled which requires that the pump be taken out of service. Accordingly, there is a need for an improved pump whereby the seals disposed between the shaft and the rotor can be quickly and easily changed or serviced on-site and without the need for taking the pump out of service.
Further, there is a need for a rotary lobe pump whereby the shaft/rotor seals can be easily accessed for repair and maintenance with a minimum of pump disassembly.
SUMMARY OF THE INVENTION
The present invention satisfies the aforenoted needs by providing a rotary lobe pump that comprises a shaft extending through a rotor case before being connected to a rotor at a shaft/rotor connection. The rotor comprises an inside surface oppositely disposed to an outside surface of the shaft. The pump further comprises a seal assembly for providing a seal between the inside surface of the rotor and the outside surface of the shaft.
The seal assembly comprises a sleeve support through which the shaft passes before the shaft is connected to the rotor. The sleeve support is fixedly connected to the rotor case. The sleeve support extends from the rotor case along the shaft and towards the shaft/rotor connection. The sleeve support passes through an elongated seal.
The elongated seal is disposed between the shaft/rotor connection and the rotor housing. The elongated seal is frictionally secured to the outer surface of the seal support and extends radially outwardly to engage the inside surface of the rotor.
In an embodiment, the elongated seal comprises a multiple lip seal.
In an embodiment, the multiple lip seal comprises an outer side comprising a plurality of lips that extend radially outwardly at an angle towards the rotor case. The lips each comprise a distal end that engages the inside surface of the rotor.
In an embodiment, the elongated seal comprises an external packed gland seal.
In an embodiment, the packed gland seal comprises a plurality of packed glands having an outside surface that engages the inside surface of the rotor.
In an embodiment, the sleeve support comprises an outer surface with at least one circumferential groove disposed therein for accommodating an O-ring. The O-ring is trapped between the sleeve support and the elongated seal.
In an embodiment, the sleeve support comprises two circumferential grooves for accommodating O-rings trapped between the outer surface of the sleeve support and the inside surface of the elongated seal.
In an embodiment, the inside surface of the rotor accommodates a wear sleeve. The elongated seal engages the wear sleeve.
In an embodiment, the inside surface of the rotor comprises a slot for accommodating a wear sleeve. The elongated seal engages the wear sleeve.
In an embodiment, the sleeve support comprises a threaded section disposed opposite the rotor case from the rotor. The threaded section threadably receives a threaded lock ring. The threaded lock ring engages the rotor case and secures the sleeve support against the rotor case.
In an embodiment, at least one seal is disposed between the rotor case and the sleeve support.
In an embodiment, the present invention provides a pump driven by a motor drive. The pump comprises a drive shaft having an end for connection to a drive mechanism. The end of the drive shaft matably receives a splined insert. The splined insert matably connects with a motor drive. The splined insert is secured within the end of the drive shaft with an adhesive. Accordingly, the splined insert can be removed and replaced with another splined insert for purposes of matably engaging the other splined insert with another motor drive.
In an embodiment, the adhesive is LOCTITE® 648.
In an embodiment, the pre
Denion Thomas
Marshall O'Toole Gerstein Murray & Borun
Trieu Theresa
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