Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2000-07-05
2002-08-13
Schuberg, Darren (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S707000, C136S204000, C062S003300
Reexamination Certificate
active
06434000
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an improved environment system for sealed hard disk assemblies, and more particularly to a system that extends the operating life of the hard disk assemblies when subject to high operating temperatures.
2. Description of the Prior Art
FIG. 1
schematically illustrates a commercially available sealed, hard disk drive and its environment control enclosure that makes the disk drive suitable for use in rugged applications where it is subject to high temperature and mechanical shock and/or vibration. One such sealed hard disk and environment control enclosure is available from Miltope Corporation and referred to by Miltope as the LPC Series of rugged high capacity, low profile, shock and vibration resistant disk drives employing sealed, disk drive housings. These products are ruggedized for operation in severe field environment where extremes of temperature, shock, vibration, humidity and air pressure are common. They are designed for “on-the-move” operation in tracked and wheeled vehicles, as well as airborne and shipboard applications. As illustrated in
FIG. 1
, this prior art disk drive includes a commercially available sealed hard disk drive
10
, such as the sealed hard disk drive available from Toshiba, IBM Corp., Seagate and others. Such hard disk drives include a disk housing
12
, which is sealed except for a very small opening
14
that allows a small amount of gas sealed in the housing
12
to egress and ingress during disk start up and shut down respectively. A hard disk
16
within the housing
12
rides on a spindle
17
driven by a motor
18
, both of which are also located within the housing
12
. A flying head
20
is servo positioned over a desired track on the disk
16
in order to read from and write data onto the disk. The housing
12
is supported in a sealed, ruggedized hard disk drive housing
22
by resilient mounts
24
, i.e. devices to mechanically isolate rapid acceleration due to shock or vibration, for example, of the hard disk drive housing
22
from the disk housing
12
. The hard disk drive housing
22
is an air tight aluminum housing filled with an inert gas or, if desired, with dry or low humidity air. This sealed aluminum housing
22
can also house a control electronics module
30
. An embedded closed loop servo system compensates for temperature variation, ensuring reliable head positioning. An air tight connector
32
provides a signal and power interface between the components inside the hard disk drive housing
22
and connections (not shown) outside of the housing. As will be appreciated by those skilled in the art, hard disk drives of the type shown schematically in
FIG. 1
, store multi-gigabytes of data on a 2.5 inch or 3.5 inch disk, with the hard disk drive housing
22
having a foot print of approximately 5 inches by 8 inches by 1.5 inches deep for a 3.5 inch disk, or appropriately smaller for a 2.5 inch or smaller hard drive. The expected mean time between failures is normally in excess of 100,000 hours in a normal environment application.
While quite satisfactory in normal office type operation, the hard disk drive systems of the type shown in
FIG. 1
have experienced a significant increase in failures when operating at very high temperatures.
SUMMARY OF THE INVENTION
An object of this invention is the provision of a hard disk drive system with a small footprint and rugged shock resistance (i.e. of the type described in connection with
FIG. 1
) but which can operate in a high temperature and/or high humidity environment without a significant decrease in mean time between failure.
Applicant has identified the cause of an increase in failure rate of hard disk systems operating in high temperature environments as the lubricant used to lubricate the disk drive motor
18
. Oil from the spindle motor has been found to wick and/or vaporize out of the motor bearing when operated at high temperatures. The lubricant has been found to form a deposit on the flying head and disk surface, eventually causing it to contact the disk and cause permanent damage as well as cause spindle motor bearing failure which causes permanent damage. In addition, when the hard drive is turned on, internal air is expelled as the air is heated through the breathing hole/filter generally used in disk drives of the magnetic media type due to the high speed rotation of the disk platter. When a drive is powered off, and cools down, make-up air is drawn in. If humidity is present, the make-up air can contain humidity or other contaminants which can deposit residue on the read/write head and disk platters, which can cause unstable flying of the read/write head and cause damage to the unit which can result in permanent failure. In addition, the disk drive electronics have caused circuit drifts and failures at temperatures above 135° F.
Applicant's solution to the problem that applicant has identified is to provide an active heat transfer device inside an environmental housing in which the hard disk drive housing is placed, in order to transfer heat away from the hard disk drive without necessarily increasing the overall footprint of the system or coupling shock or vibration from the environmental housing to the disk drive. In some embodiments of the invention, the active heat transfer device is a thermoelectric solid state heat pump that uses the Peltier effect to move heat. As will be appreciated by those skilled in the art, such solid state heat pumps are commercially available, for example from Melcor corporation. These heat pumps consist of a number of p type and n type pairs connected electrically in series and sandwiched between two ceramic plates. When the heat pumps are connected to a d.c. source, current causes heat in each heat pump to move from one plate to the other, making one ceramic plate a relatively hot plate and the other ceramic plate a relatively cool plate, and creating a relatively hot side and a relatively cool side on the heat pump. In one embodiment of the invention, the environmental housing comprises an outer shell of a heat conductive material, such as aluminum, and a receptacle for receiving a hermetically sealed hard disk drive housing or cartridge. The receptacle comprises two side walls and a bottom wall, all made of heat insulating material, such as polyurethane, and a top wall comprising a heat conducting structure of a heat conducting material, such as aluminum. The heat pump is interposed between the heat conducting structure and the outer shell of the environmental housing, with the cool side of the heat pump contacting the heat conducting structure of the receptacle, and the hot side of the heat pump contacting the outer shell of the environmental housing. Fins of heat conducting material, such as aluminum, are positioned on the outside of the environmental housing. The heat insulation minimizes the transfer of heat from a hot environment to the disk drive, and heat in the disk drive is transferred to the environment by the active heat transfer device and the environmental housing, including the fins.
An arrangement is provided for biasing the hard disk drive housing into heat conducting contact with the heat conducting structure of the environmental housing.
In one embodiment, the biasing arrangement comprises wedge members interposed between the disk drive housing and the environmental housing, the wedge members cooperating with one another to bias the disk drive housing into heat conducting contact with the heat conducting structure of the environmental housing. The wedge members are associated with actuating mechanisms having portions which block the environmental housing door from closing when the disk drive housing is not in flat, heat conducting contact with the heat conducting structure and which permit the door to close when the disk drive housing is in flat, heat conducting contact with the heat conducting structure. Portions of the actuating mechanisms use the environmental housing as a fulcrum to eject a portion of the disk drive housi
Anderson Chad C.
Duong Hung Van
IV Phoenix Group Inc.
Schuberg Darren
Shannon John P.
LandOfFree
Environmental system for rugged disk drive does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Environmental system for rugged disk drive, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Environmental system for rugged disk drive will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2893010