Underwater electromechanical timer

Details Underwater electromechanical timer Underwater electromechanical timer

2001-12-19

2003-03-18

Martin, David (Department: 2841)

Horology: time measuring systems or devices

Time interval

Mechanical stop time type

C368S107000, C368S110000, C307S141000, C307S141400

Reexamination Certificate

active

06533451

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates generally to timer devices, and more particularly, to an underwater electromechanical timer that can be timely programmed to activate an external device connected to the underwater electromechanical timer.
2. Description of the Related Art
Timer devices are well known to provide delayed activation of various types of devices. Conventionally, the structure and mechanism of timer devices are specifically in accordance with its conditions of use. The following description particularly refers to an example of underwater timer.
In navigation, maritime ships happen to ground between submerged reefs, putting the ships in difficulty. In those situations, explosives are conventionally used to remove the submerged reefs. The explosives are adequately disposed on the site of submerged reefs, and underwater timers are typically connected to the explosives to trigger timely-programmed explosions.
FIG. 1
is a cross-sectional view that depicts a conventional underwater timer known in the art. The conventional underwater timer
10
comprises a casing
15
in which the slide of a control bar
17
enables to timely turn a switch
18
. The control bar
17
is tightly mounted with a collar pad
12
that lies on a salt dissolvable supporting block
14
to support and keep the control bar
17
away from the switch
18
. To activate the timer
10
, the latch
13
that locks the control bar
17
within the casing
15
is first removed. The underwater timer
10
then is put into water. Salt dissolvable supporting block
14
contacting with water then progressively dissolves in water, which causes a progressive slide of the control bar
17
to contact with the switch
18
. A rubber membrane
16
is conventionally arranged within the casing
15
to isolate the switch
18
from water contact.
The above conventional timer
10
using a salt element has several deficiencies. The dissolution of the salt element in water is difficult to control with respect to time programming purposes because multiple factors may influence the dissolution velocity. For example, under substantially high water pressure, the salt element may crack into several pieces, which increases the contact area of the salt element with water and consequently accelerates its dissolution in water. The salt element may also easily crack into smaller pieces when the timer is transported. Besides, the waterproof rubber membrane
16
may be damaged due to high water pressure, which restrains the use of the timer to limited water depths. A more reliable, robust, and precise underwater timer is thus needed.
SUMMARY OF THE INVENTION
An aspect of the invention is therefore to provide an underwater electromechanical timer that can be precisely programmed, and provides a precise activation of the devices connected to the timer without being affected by external water pressure.
Another aspect of the invention is to provide an underwater electromechanical timer that can be used in water depth levels higher than the conventional water depth levels.
Yet, another aspect of the invention is to provide an underwater electromechanical timer that is reliable and robust.
To accomplish the above and other objectives, an underwater electromechanical timer of the invention comprises the following elements installed within a casing structure. A motor-driven timer assembly mounted in the casing structure comprises a threaded member that engages an endless screw driven in rotation via a motor. Time programming of the timer is accomplished by presetting a length of sliding of the threaded member along the endless screw. The sliding threaded member causes a timely switching event of a device switch placed within the casing structure. An external device that is electrically connected to the device switch is thereby activated. To activate the timer, an activation mechanism comprised of a plunger is mounted in the casing structure. The activation mechanism is externally exposed. Under adequate external pressure exerted on the activation mechanism, the activation mechanism connects the endless screw with an output of the motor to drive the rotation of the endless screw, and causes a slide of the threaded member. The turn-on and turn-off of the motor are achieved through switches placed in the casing structure. The turn-on of the motor is effectuated by the activation mechanism once the activation mechanism has engaged the endless screw with the output of the motor. The turn-off of the motor is effectuated when the threaded member has reached the end of its sliding course. Resilient controller and protection elements are further mounted between the endless screw and the motor and between the device switch and the threaded member to prevent undesired activation events, thereby improving the reliability and robustness of the timer.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.


REFERENCES:
patent: 2991403 (1961-07-01), Groft
patent: 3679951 (1972-07-01), Whitlock
patent: 4107546 (1978-08-01), Sturman et al.
patent: 4766331 (1988-08-01), Flegel et al.

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