# Patent

## Title
Pressure switch

## Abstract

A water pressure switch employs two pivotable plates and springs to control the activation of the pump. The arrangement of the two pivotably plates, the springs and the activation device reduces the space required so that a small box can accommodate all the parts.

## Background
FIELD OF THE INVENTION
The present invention relates to a pressure switch wherein the first and second plates and the switch device are located in a center of the box and occupy less space.
BACKGROUND OF THE INVENTION
A conventional pressure switch 9 is shown in FIG. 7 and generally includes a push member 91, a first plate 92, a second plate 93, a first contact point 94, a second contact point 95, a spring member 96 and a rectangular box 97 which receives all the parts therein. When the pressure of water is too low, the pump can be automatically activated to maintain a desired pressure in pipes.
When the pressure of water is high, the push member 91 pushes the first plate 92 which drives the second plate 93 and the first contact point 94 is moved by the second plate 93 to be separated from the second contact point 95 so as to stop the pump.
When the water pressure in pipes is lowered and smaller than the spring force of the spring member 96 in the pressure switch 9, the spring member 96 drive the two contact points 94, 95 to be in contact with each other to activate the pump.
However, when the direction of water flow form the inlet 98 and the swing direction of the first contact point 94 need a certain space to work so that the box 97 has to be large enough to receive all the parts therein. Besides, the inlet 98 is located off from the center of the box 97 so that it requires a larger space to install the box 97.
The present invention intends to provide a pressure switch wherein the direction of water flow form the inlet and the swing direction of the contact point are the same so that the box can be a cylindrical box and the inlet is located at the central axis of the box. This reduces the manufacturing cost and needs a smaller space to install the box of the pressure switch as well.
SUMMARY OF THE INVENTION
The present invention relates to a pressure switch which comprises a box and an outer cover is connected to an open end of the box and an inlet is defined through the outer cover, an inner cover is engaged with the open end and has a central hole. A film is located between the outer cover and the inner cover, and has a push portion which extends through the inner cover. An initializing device has a rod and a first spring which is mounted to the rod and one end of the rod extends through a close end of the box. A first plate has a pivot end pivotably connected to the inner cover and a through hole is defined through the first plate. The first plate is located between the first spring and the push portion. A mounting hole is defined through the first plate so that the rod extends through the mounting hole. A second plate extends through the through hole of the first plate and has a pivotal end which is located opposite to the pivot end of the first plate and connected to the inner cover. An activation device is located above the first and second plates and includes a frame and a pull rod which is connected to a center of the frame. A second spring member is connected between a lug of the second plate and the pull rod. A first contact unit and a second contact unit are located on two sides of the pull rod and connected to the frame. When the pull rod is pulled by the second spring, the first and second contact units are in contact with each other.
The present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a preferred embodiment in accordance with the present invention.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows the pressure switch of the present invention;
FIG. 2 shows that the first and second contact units are in contact with each other;
FIG. 3 shows that the first and second plates are pulled upward;
FIG. 4 shows that the first and second contact units are separated from each other;
FIG. 5 shows the first plate of the present invention;
FIG. 6 shows the second plate of the present invention, and
FIG. 7 shows a conventional pressure switch.



DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIGS. 1 to 6, the pressure switch of the present invention comprises a cylindrical box 1 which has a space 11 defined therein and includes a close end 12 and an open end 13. An outer cover 2 is connected to the open end 13 of the box 1 and an inlet 21 is defined through the outer cover 2 so as to introduce water into the box 1. An inner cover 3 is engaged with the open end 13 and has a central hole 31. A film 4 is located between the outer cover 2 and the inner cover 3, and has a push portion 41 which extends through the central hole 31 of the inner cover 3.
An initializing device 5 located in the box 1 and has a rod 51 and a first spring 52 mounted to the rod 51. An adjustment member 53 is threadedly connected to the rod 51 and located above the first spring 52. The rod 51 has one end extending through a hole 64 in the close end 12 of the box 1 and is connected to a nut 54.
A first plate 6 has a pivot end 61 pivotably connected to the inner cover 3 and a through hole 62 is defined through the first plate 6. The first plate 6 is located between the first spring 52 and the push portion 41. A mounting hole 64 is defined through the first plate 6 and the rod 51 extends through the mounting hole 64. The first plate 6 includes two openings 63 so that a tip of the push portion 41 may extend therethrough. A second plate 7 extends through the through hole 62 of the first plate 6 and has a pivotal end 71 which is located opposite to the pivot end 61 of the first plate 6 and connected to the inner cover 3.
An activation device 8 is located above the first and second plates 6, 7 and including a frame 81 and a pull rod 82 which is connected to a center of the frame 81. A second spring member 83 is connected between a lug 72 located at a center of the second plate 7 and the pull rod 82. A first contact unit 84 and a second contact unit 85 are located on two sides of the pull rod 82 and connected to the frame 81. The frame 81 includes two tip portions 811, 812 with the pull rod 82 located therebetween, the two tip portions 811, 812 respectively contact the first contact unit 84 and the second contact unit 85.
In order to reinforce the spring force that is applied to the first plate 6, a third spring 55 is mounted to the rod 51 and located at inner periphery of the first spring 52. Each of the first and second plates 6, 7 has a hook hole 65/73 so that a fourth spring 74 is hooked the two respective hook holes 65, 73 in the first and second plates 6, 7.
The first contact unit 84 has a first upper contact portion 841 and a first lower contact portion 842, a fifth spring 86 is connected to the first upper contact portion 841. The second contact unit 85 includes a second upper contact portion 851 and a second lower contact portion 852, a sixth spring 87 is connected to the second upper contact portion 851.
When the water pressure is lowered, the pull rod 82 is pulled downward by the second spring member 83 so that the first and second upper contact portions 841, 851 are in contact with the first and second lower contact portions 842, 852. The electrical wires 88 of the first and second contact units 84, 85 are powered so as to activate the pump which is not shown.
When the water pressure is larger than the force of the first spring 52, the push portion 41 of the film 4 is pushed inward to push the first plate 6 and pivots the second plate 7 upward. The pull rod 82 connected to the lug 72 on the second plate 7 an the second plate 7 both push the frame 81 so that the first and second upper contact portions 841, 851 are separated from the first and second lower contact portions 842, 852. The fifth and sixth springs 86, 87 bounce back to ensure all the contact portions are separated to stop the pump.
The two tip portions 811, 812 are in contact with the two respective centers of the first contact unit 84 and the second contact unit 85 so that the first and second contact units 84 and 85 apply an even force which prevents the pressure switch from shaking. The direction of the water flow from the inlet 21 and the direction of the movement of the fist and second contact units 84, 85 are the same, so that only a smaller space is needed and the inlet 21 is located at a center of the box 1 which is convenience for installation.
While we have shown and described the embodiment in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.

## Claims

1. A pressure switch comprising:
a box having a space therein and including a close end and an open end;
an outer cover connected to the open end of the box and an inlet defined through the outer cover;
an inner cover engaged with the open end and having a central hole;
a film located between the outer cover and the inner cover, a push portion extending from the film;
an initializing device having a rod and a first spring mounted to the rod, the rod located in the space of the box and has one end extending through the close end of the box;
a first plate having a pivot end pivotably connected to the inner cover and a through hole defined through the first plate, the first plate located between the first spring and the push portion, a mounting hole defined through the first plate and the rod extending through the mounting hole;
a second plate extending through the through hole of the first plate and having a pivotal end which is located opposite to the pivot end of the first plate and connected to the inner cover, a lug located at a center of the second plate, and
an activation device located above the first and second plates and including a frame and a pull rod which is connected to a center of the frame, a second spring member connected between the lug of the second plate and the pull rod, a first contact unit and a second contact unit located on two sides of the pull rod and connected to the frame, when the pull rod is pulled by the second spring, the first and second contact units are in contact with each other.

2. The switch as claimed in claim 1, wherein the push portion of the film extends through the central hole in the inner cover.

3. The switch as claimed in claim 1, wherein the initializing device includes an adjustment member located on the rod and above the first spring.

4. The switch as claimed in claim 1, wherein the first plate includes two openings so that a tip of the push portion extends therethrough.

5. The switch as claimed in claim 1, wherein a third spring is mounted to the rod and located at inner periphery of the first spring.

6. The switch as claimed in claim 1, wherein each of the first and second plates has a hook hole so that a fourth spring is hooked the two respective hook holes in the first and second plates.

7. The switch as claimed in claim 1, wherein the frame includes two tip portions with the pull rod located therebetween, the two tip portions respectively contact the first contact unit and the second contact unit.

8. The switch as claimed in claim 1, wherein the first contact unit has a first upper contact portion and a first lower contact portion, a fifth spring is connected to the first upper contact portion, the second contact unit includes a second upper contact portion and a second lower contact portion, a sixth spring is connected to the second upper contact portion.