Chemistry: electrical current producing apparatus – product – and – Cell support for removable cell – For plural cells
Reexamination Certificate
1999-04-08
2001-05-01
Maples, John S. (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Cell support for removable cell
For plural cells
C429S157000, C429S159000, C429S177000, C429S178000
Reexamination Certificate
active
06224997
ABSTRACT:
FIELD OF INVENTION
In order to gather information relating to the conditions existing at some depth below the surface of an oil or gas well, the well operator frequently lowers electronic sensing equipment into the well which by its nature requires an electrical energy source (battery pack) to provide the energy for sensing, recording and the remote transmission of the various parameters being measured at the location of equipment in the well. The battery pack must be of a particular size and configuration to be accommodated by the drilling or servicing apparatus. Typically, such battery packs have been in the shape of elongated cylinders having electrical terminals at one or both ends of the battery pack for connection to the electronic equipment. The battery pack must operate in conditions which could be best described as being extremely hostile. Wide variations in temperature and pressure of the medium surrounding the battery pack can be expected. At times, the battery pack must withstand severe vibrations which can cause the premature failure of the battery pack by rupture etc. with the consequent loss of the capability to monitor and transmit the well parameters being sensed. It is an expensive and time consuming operation to retrieve the electronic monitoring equipment just to replace a failed battery pack.
BACKGROUND OF THE INVENTION
Oil and gas well drilling and servicing equipment, in the past, has made successful use of elongated cylindrically shaped battery packs which may be used with well tools to provide the power necessary for the operation of the downhole equipment.
Prior art battery packs may contain a plurality of cylindrically shaped energy cells which are physically arranged in an end to end relationship and are individually wired to suit the energy requirements of the equipment with which the battery pack is being used. Usually, the energy cells are connected by insulated conductive straps which are connected to each cell by welding or soldering and the individual cells are connected to a pair of bus conductors extending down the side of the battery pack. These connecting straps are usually insulated from the string of energy cells except where connections are being made. The energy cells and the strap connections are usually encased in some kind of tubular enclosure, such as paper or similar substance, in which the internal diameter of the enclosure is slightly greater than the diameter of the string of connected energy cells and the thickness of the bus connecting straps which pass along the side of the energy cells. The tubular enclosure is provided with a coating of an impervious material such as plastic and a sealed terminal structure is formed at one or both ends of the tubular enclosure.
Failure of prior art battery packs in the hostile environment in which they are forced to operate is usually due to fracture and leakage of the tubular enclosure securing the individual cells together. At times, the vibration in the medium surrounding the battery pack may cause the abrasion and fracture of the flat strap type bus conductors which connect the individual cells together, leading to open circuiting of the bus conductors and in some instances, short circuiting of the bus conductors and the resultant premature discharge of the battery pack. At times the failure of the bus conductors can produce an arc which may cause the battery pack to explode.
Although every attempt is made to seal the prior art battery packs against leakage of the surrounding medium into the interior thereof, when severe operating conditions are encountered, some of the corrosive components (i.e. hydrogen sulfide) of the surrounding medium may penetrate into the interior of the battery pack causing components of the battery pack not only to fail prematurely but also to corrode and swell so that removal of such a failed battery pack from its housing is often difficult if not impossible to do.
SUMMARY OF THE INVENTION
This invention seeks to provide a self contained somewhat flexible battery pack for downhole equipment which is robust and resistant to failure in the modes of the prior art battery packs previously described.
The battery pack of this invention is composed of individual cells which may be interconnected by insulated strap type conductors which are welded in a predetermined manner to the positive and negative surfaces of the individual cells of the battery pack to produce the desired output potential. A set of bus conductors extend up the side of the individual cells and are connected into an external terminal structure of the battery pack (usually at the top).
The individual cells, so connected, are encased in a pair of half cylindrical (clam shell) containment members which are assembled to fit together to hold the individual cells in the cavity formed in the interior thereof as well as any bus type strap connectors which are required to connect the interconnected cells to the terminals of the battery pack. Damage to the battery pack caused by vibration and other shocks is largely eliminated. The clam shells are preferably formed from a suitable plastic material or reinforced high impact plastic material such as a glass fiber reinforced polymeric material which is capable of securing the individual cells firmly in place in their predetermined locations in the stack of cells forming the battery pack. One or both of the shells is provided with a longitudinal grooved recess formed in the interior surface of the half shell extending the length of the clam shell. This recess provides space and support for the necessary connecting bus conductors (wires or straps) for the individual cells and at the same time prevents the direct application of external pressure and vibrating forces to the conductors which over a period of time can lead to failure of the conductor by abrasion and fracture.
The clam shells are provided with a pair of end plugs which are secured to the half shells in any desired manner and one or both of the end plugs may be fitted with end terminals which are connected to the bus connectors of the battery pack to energize downhole equipment.
The two clam shells containing individual energy cells, bus conductors and end terminal structure is now inserted and sealed into an outer metallic jacket (in the form of a tube) so as to inhibit the ingress of foreign material into the battery pack to complete the assembly process.
PERTINENT PRIOR ART
U.S. Pat. No. 4,675,259 Jun. 23. 1989
This patent describes a downhole battery package comprising a linear array of interconnected battery cells in a tubular case. The tubular case is preferably composed of a paper or Nomex paper. No provision is made for the protection or stowage of the electrical lead conductors such as conductive paths shown as
14
and
16
in the battery package. This battery pack is not robust; the entire case may fracture if severe bending of the battery pack is experienced. Even if this battery package does not rupture during use, it is subject to leakage of the surrounding medium into the interior of the battery pack because of its fragile nature.
U.S. Pat. No. 4,970,073
This patent describes a battery pack composed of serially connected cells which are enclosed in reinforcing members which are typically glass fiber sleeves surrounded by binding tape. Standard insulated wire conductors serve to connect terminals of the terminals of the battery pack to the serially connected cells. The interconnected cells and the conductors are inserted into a metal or epoxy tube where a thermosetting encapsulating compound is introduced. The resulting battery pack is a very rugged piece of equipment which is very strong physically and is very resistant to bending. The encapsulating material used in the manufacture of this battery pack takes up precious volume which in most battery packs would be put to better use by increasing the size of the cells used to power the battery pack. The rugged construction of this battery pack renders it incapable of undergoing distortion such as bending, thus, the above battery pack is e
Maples John S.
Oldham Edward H.
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