Underwater electromechanical timer

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.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings,

FIG. 1

is a cross-sectional view of a conventional underwater timer; and

FIG.

2

A and

FIG. 2B

are cross-sectional views illustrating an underwater electromechanical timer according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following detailed description of the embodiments and examples of the present invention with reference to the accompanying drawings is only illustrative and not limiting. Wherever possible in the following description and accompanying drawings, like reference numerals and symbols will refer to like elements and parts unless otherwise described. In the description, the terms “downwardly”, “upwardly”, “below”, “upper”, “central”, and “lower” are used in reference to the description drawings.

Referring to

FIG. 2A

, a cross-sectional view schematically illustrates an underwater electromechanical timer according to an embodiment of the invention.

FIG. 2

shows a configuration where the timer is not activated. An upper part of an underwater electromechanical timer

100

comprises an upper casing

102

through which is defined a guiding cavity

104

that passes through the upper casing

102

. A plunger

106

slidably fits in the guiding cavity

104

. The plunger

106

comprises an upper plunger

108

that upwardly terminates into a portion externally exposed, and a lower plunger

110

that terminates within an interior of the upper casing

102

. A waterproof joint

112

is disposed between the upper plunger

108

and the lower plunger

110

to prevent water penetration within the casing structure. Hence arranged, the plunger

106

can longitudinally slide along the guiding cavity

104

if a pressure differential is generated between the interior and the exterior of the upper casing

102

. A removable latch pin

114

is externally inserted through the upper casing

102

and the plunger

106

at an upper portion of the upper casing

102

to lock the position of the plunger

106

within the guiding cavity

104

.

Within the upper casing

102

, a carrier guiding block

116

is further mounted below the plunger

106

. The carrier guiding block

116

is mounted in a manner to slide downwardly when pushed by the plunger

106

. A motor

118

is mounted in the carrier guiding block

116

with a driving wheel

120

of the motor

118

downwardly protruding out of the carrier guiding block

116

. The motor

118

further upwardly abuts against the plunger

106

. A motor starter switch

122

that is electrically connected to the motor

118

is further mounted to the carrier guiding block

116

. The motor starter switch

122

downwardly protrudes out of the carrier guiding block

116

into a switch contact pad

124

. In the example of this embodiment, the motor starter switch

122

is exemplary illustrated as a mechanical switch which switching event is caused by mechanical contact.

A central part of the timer

100

further comprises a central casing

126

. The central casing

126

may be fixedly and tightly attached to the upper casing

102

via various fastener members such as screw assemblies, for example. A guiding cavity

128

is defined through the central casing

126

while an abutting surface

130

defined within the central casing

126

is remotely vis-a-vis the switch contact pad

124

of the motor starter switch

122

. A resilient pressure controller

132

, for example a spring, is mounted within the upper casing

102

in a manner to be oppositely connected to the carrier guiding block

116

and the central casing

126

.

Within the central casing

126

, a mechanical timer assembly comprised of endless screw

134

and threaded member

140

is coaxially mounted through the guiding cavity

128

. The endless screw

134

is pivotably mounted through the guiding cavity

128

via a ball bearing

136

. The endless screw

134

further upwardly terminates into a transmission wheel

138

that is coaxial with the endless screw

134

and upwardly protrudes out of the central casing

126

. The endless screw

134

and the transmission wheel

138

are assembled in a manner to be rotatably dependent on each other, and the transmission wheel

138

is designed in manner to be able to engage and be driven by the driving wheel

120

. In addition, the endless screw

134

and the transmission wheel

138

are spaced apart from the driving wheel

120

. The distance between the transmission wheel

138

and the abutting surface

130

and the distance between the driving wheel

120

and the switch contact pad

124

are set in a manner to cause a mechanical contact of the abutting surface

130

with the switch contact pad

124

once the driving wheel

120

has engaged the transmission wheel

138

. The threaded member

140

has an external profile in compliance with the guiding cavity

128

to longitudinally slide therein when the endless screw

134

rotates. Time programming of the timer

100

is accomplished via presetting a specific length of sliding of the threaded member

140

along the endless screw. The guiding cavity

128

is downwardly closed via a collar

142

through which the endless screw

134

passes.

A lower part of the timer

100

further includes a lower casing

144

. The lower casing

144

may be fixedly attached with the central casing

126

via, for example, fastener members such as screw assemblies. It should be noticed that for assembly convenience, the casing structure of the timer

100

is described as being formed of upper, central, and lower casings in the present embodiment. However, those skilled in the art would readily understand that other casing structures may be also adequate without departing from the inventive concepts of the underwater electromechanical timer

100

of the invention.

A resilient protection element

146

, for example a spring, is mounted within the lower casing

144

in a manner to be oppositely connected to the collar

142

and the lower casing

144

. A motor stop switch

148

that is electrically connected to the motor

118

is disposed within the lower casing

144

. The motor stop switch

148

upwardly protrudes into a switch contact pad

150

that is remotely vis-à-vis the collar

142

. At least one device switch

152

that is electrically connected to an external device

200

is mounted in the lower casing

144

. Similar to the motor stop switch

148

, the device switch

152

upwardly protrudes into a switch contact pad

154

that is remotely vis-à-vis the collar

142

. In the example of this embodiment, the motor stop switch

148

and the device switch

152

are exemplary mechanical switches which switching event is caused by mechanical contact with their respective switch contact pads

150

,

154

.

The motor stop switch

148

additionally may be electrically connected to another external device

202

. The turn-off of the motor

118

and the activation of the external device

202

can be therefore substantially simultaneous.

A reading display

156

with graduations

158

thereon is further arranged on the central casing

126

. The position of the threaded member

140

on the endless screw

134

can be thereby visually controlled. The endless screw

134

downwardly terminates into a rotary element

160

. The rotary element

160

is externally exposed through the lower casing

144

so that a user can program the underwater electromechanical timer

100

via turning the rotary element

160

to set the position of the threaded member

140

on the endless screw

134

.

The operation of the above underwater electromechanical timer

100

is now described with the help of FIG.

2

A and FIG.

2

B.

FIG. 2B

shows the underwater electromechanical timer

100

in a configuration where time counting is completed.

Through the reading display

156

, the user first programs the timer

100

with a desired time interval via turning the rotary element

160

, which sets a starting position of the threaded member

140

on the endless screw

134

. A programmed time interval may be, for example, 60 minutes. When the timer

100

is at a sufficient water depth, exterior water pressure greater than the interior pressure presses on the plunger

106

.

The plunger

106

hence downwardly pushes the motor

118

and the carrier guiding block

116

to engage the driving wheel

120

with the transmission wheel

138

and further put the switch contact pad

124

in mechanical contact with the abutting surface

130

, which turns on the motor

118

. The plunger

106

and the carrier guiding block

116

hence achieve an activation mechanism of the timer that is directed to activate the mechanical timer assembly.

The driving wheel

120

consequently drives the rotation of the endless screw

134

via the transmission wheel

138

, which results in a progressive slide of the threaded member

140

downwardly along the endless screw

134

. To adapt the timer

100

with various ranges of time delay, a differential mechanism (not shown) may be further coupled between the driving wheel

120

and the transmission wheel

138

.

The sliding threaded member

140

establishes a mechanical contact with the switch contact pads

150

,

154

of the motor stop switch

148

and device switch

152

via pushing the collar

142

thereon, thereby timely causing a switching event of the motor switch

148

and the device switch

152

. The motor

118

is consequently turned off, which stops the slide of threaded member

142

. Damages of the threads of the endless screw

134

and threaded member

142

are thereby prevented. Meanwhile, the device

152

is timely activated. If the motor stop switch

148

is also electrically connected to an external device

202

, the device

202

is also activated.

For reliability and robustness consideration, the resilient pressure controller

132

ensures that both carrier guiding block

116

and motor

118

are spaced apart from the mechanical timer assembly when no water pressure is exerted on the plunger

106

. Undesired activation of the motor

118

through mechanical contact with the motor starter switch

122

is thereby prevented. Meanwhile, the resilient protection element

146

prevents any contacts of the collar

142

with the switch contact pads

150

,

154

that are not caused by a push of the threaded member

140

. Undesired activation of the external device

152

,

202

is therefore also prevented.

In conclusion, the invention provides an underwater electromechanical timer that is precise, robust, and reliable. Constructed with the motor-driven mechanical timer assembly that can be accurately preset, the timer of the invention provides a timely precise activation of various devices connected to the timer. By including controller and protection elements that prevent undesired activation, the timer of the invention is further reliable and robust. Furthermore, being activated via pressure water, the timer of the invention can be used within a water depth range of about 10 meters to about 1000 meters, the level of 1000 meters can be possibly exceeded. The timer of the invention can be therefore used in a broader range of water depths in comparison with conventional underwater timers that use dissolving salt.

It should be apparent to those skilled in the art that other structures that are obtained from various modifications and variations of various parts of the above-described structures of the invention would be possible without departing from the scope and spirit of the invention as illustrated herein. Therefore, the above description of embodiments and examples only illustrates specific ways of making and performing the invention that, consequently, should cover variations and modifications thereof provided they fall within the inventive concepts as defined in the following claims.