US3794168A

US3794168A - Filter with condition indicator

Info

Publication number: US3794168A
Application number: US00276694A
Authority: US
Inventors: G Perkins
Original assignee: Parker Hannifin Corp
Current assignee: Parker Hannifin Corp
Priority date: 1972-07-31
Filing date: 1972-07-31
Publication date: 1974-02-26
Anticipated expiration: 1991-02-26
Also published as: GB1413366A; DE2335276A1; JPS4958466A; CA996659A

Abstract

A filter assembly having a cylinder and piston movable therein by the pressure differential across the filter element and the piston carrying a metal ring to connect various indicator lights with a source of power at various pressure differentials to show the cleanliness condition of the filter element at various stages.

Description

United States Patent [1 1 Perkins 1 1 Feb. 26, 1974 1 1 FILTER WITH CONDITION INDICATOR 3,545,616 12/1970 Aspinwall et a1. 2 10 911 [75] .lnventor: Gerard T. Perkins, Detroit, Mich. RE N PATENTS A P I [73] Assignee; Parker.l-[annifin Corporation, 142,723, /1901 Germany 200/16 13 Cleveland, Ohio 1,155,187 /1963 Germany 200/16 B [22] Flled: July 1972 Primary Examiner.1ohn Adee [21] Appl. No.: 276,694 Assistant Examiner-Robert H. Spitzer Attorney, Agent, or Firm-John N. Wolfram [52] U.S. C1 210/90, 210/130, 210/232 I [51] Int. Cl .L BOld /14 [57] ABSTRACT [58] Field of Search 2 2 A filter assembly having a cylinder and piston movable 2l0/DI 1 13 therein by the pressure differential across the filter e1- 56] References Cited ement and the piston carrying a metal ring to connect various Indicator lights with a source of power at vari- UNITED STATES PATENTS ous pressure differentials to show the cleanliness con- 3,323,649 6/1967 Rosaen 210/ dition of the filter element at various stages. 3,046,369 7/1962 Hicks 3,644,915 2/1972 McBurnett 340/239 5 Claims, 1 Drawing Figure vz 9| w, 1

FILTER WITH CONDITION INDICATOR BACKGROUND OF THE INVENTION Heretofore, filter devices have been provided with mechanical and/or electrically actuated means for indicating the cleanliness condition of the filter element. Electrical indicators in the form of lights are advantageous in that they may be easily read and also lend themselves to mounting at a position remote from the filter assembly. However, electrically actuated indicators have been used previously to show only the clogged condition of the filter.

SUMMARY OF THE INVENTION The present invention is an improved method of sensing and indicating the cleanliness condition of a filter. The sensing mechanism includes a cylinder havinga piston therein that is exposed to fluid pressures upstream and downstream of the filter element to be monitered and which carries an electrical conductor for making a circuit. The cylinder has a common energized contact and one or more smaller contacts leading to a respective number of lights that comprise the indicating mechanism. As the differential in upstream and downstream pressures increases due to the filter becoming increasingly dirty, the piston is moved in the cylinder such that the lights are successively energized in a make before break configuration. Any number of lights may be used to indicate the filter condition at any number of desired stages.

In a preferred embodiment of the invention the indicating mechanism comprises three lights for indicating when the filter is clean, dirty and bypassing due to being clogged. The cylinder has an opening therein such that when the piston is at or near its furthermost point of travel due to a severely restricted or clogged filter element, fluid passes through the opening to the downstream side of the filter element, thus bypassing the latter.

The indicator lights are mounted in a separate housing member that may be mounted on the housing of the sensing mechanism so that it can be easily removed therefrom and displayed remotely. When the lights are mounted on the sensing mechanism housing both can be removed as a unit from the filter housing as a unit to facilitate replacement of the filter element.

BRIEF DESCRIPTION OF THE DRAWING The drawing is a vertical cross-sectional view of the filter device.

DETAILED DESCRIPTION Filter assembly includes a generally cylindrical housing 11, preferably of a plastic material such as polybutylene (terephthalate), with an inlet 12 and an outlet 13. Inlet 12 is in a reduced diameter portion 14 that also includes a cylindrical portion 15 and an abutment shoulder 16. r

The other end of housing 11 is open and has a radial flange and an axially extending annular projection 22. A sensing mechanism housing has a flange 23 with an axial projection 21 threaded into projection 22 to close the open end of housing 11. An O-ring 26 seals the joint between flanges 20 and 23.

Sensing mechanism housing 25 is also of plastic or non-conductive material, preferably the same material as housing 11, and includes a cylinder 31 with piston 32 of plastic or other non-electrically conductive material disposed therein. A spring 33 biases the piston against a stop pin 34 mounted on cylinder 31. Cylinder 31 has a vent opening 35 and a flow passage 36 through the side wall thereof. Piston 32 has an annular metal ring 40 disposed in a groove in the outside surface of the piston such that the ring is of substantially the same, or slightly larger diameter than the upper and lower ends of the piston. Cylinder 31 has a narrow and elongated constantly energized contact 41 embedded therein. A wire 42 runs from the contact 41 to a location outside the filter assembly 10 where it is connected to a source of power (not shown). Cylinder 31 also has contacts 43, 44, and 45 connected to

contacts

50, 51 and 52 respectively of lights 53, 54, and 55 via

wires

56, 57, and 58.

Sensing mechanism housing 25 also has an annular flange which extends first radially and then axially and which receives the upper end of a hollow cylindrical filter element 61 which is radially spaced from housing section 1 1 to provide an annular space 67. The lower end of filter element 61 is radially located by reduced diameter portion 15 of housing 11 and is sealed relative to body shoulder 16 by an O-ring 63.

Projection 21 has a cylindrical recess 64 into which a cylindrical section 66 of an indicator housing is press fitted. Lights 53, 54, and 55 are mounted in housing 65.

Contacts

50, 51, and 52 have a common wire leading from housing 64 to the power source, (not shown). Housing 65 also has an annular mounting flange 76.

OPERATION Fluid enters the interior 68 of filter element 61 via inlet 12 and normally passes through the side of the element into annular space 67 and out from the filter assembly 10 via outlet 13.

Fluid within element 61 exerts pressure on one side of piston 32 and fluid from space 67 exerts pressure on the other side of the piston via opening 35 and passage 36. When the filter is clean there is only a small pressure drop across the element 61 between its interior 68 and space 67 and hence the upward force on the piston due to the difference in pressures acting on opposite sides of the piston is quite small and is overcome by spring 33 for holding the piston against stop 34. When the piston is at or near stop 34, metal ring 40 completes a circuit between contacts 41 and 45 to energize light 55.

As solid foreign matter is filtered from the fluid it lodges in element 61 and reduces the area for passage of fluid through the element resulting in a greater pressure drop across the element and a greater differential in the pressure acting on opposite sides of piston 32 whereby the piston will move against the pressure of spring 33 until the latter has shortened sufficiently to ment 61, ring 40 disengages from contact 45 so that for a time only light 54 is energized, then it engages contact 43 so that both lights 53 and 54 are energized,

and then finally only light 53 is energized. When the latter occurs piston 32 has moved far enough to uncover passage 36 to allow fluid within element 61 to pass therethrough to the exterior of cylinder 25 and out through outlet 13 to thus effectively to bypass element 61.

To prevent hydraulic lock as piston 32 moves upward, some of the fluid within cylinder 31 is displaced therefrom, first through passage 36 and opening 35 and then only through opening 35 when the piston has moved upward enough to cover passage 36.

In the preferred embodiment of the invention the indicator light sequence is as follows:

Green Filter is clean, full filtration.

Green & Yellow Element is becoming dirty, still full filtration.

Yellow Element is dirty. Still full filtration.

Yellow & Red Element dirt has reached critical level and bypass has just cracked open. Filtration is becoming proportional.

Red Element very dirty. Bypass open, filtration be comes decreasingly proportional.

Any number or color of lights may be used to indicate element condition at any stage. The lights may be made to turn on and off in sequence as described, or they may be made to remain on when once energized by making the distance between contacts 43, 45 less than the length of ring 40.

In the arrangements as shown in the drawings, housing 65 containing lights 53, 54, and 55 is mounted directly on sensing mechanism housing 25 and both may be removed as a unit from filter housing 11 by unthreading housing 25 from projection 22 for replacing filter element 61.

If desired, indication housing 65 may be removed from the filter assembly by disengaging it at its press fit connection to housing 25 and mounting it at some remote location via flange 76.

I claim:

1. A filter device comprising a first housing member having an inlet and an outlet with a chamber therebetween and with an opening connected to the chamber, a hollow filter element in the chamber having its interior connected to the inlet and its exterior spaced from the chamber wall to provide a first annular chamber portion exterior of the element, said first chamber portion being connected to the outlet, a second housing removably attached to the first housing and extending across the opening to close the same, said second housing having a cylinder depending therefrom into the chamber and engaging the filter element to hold it in a fixed position relative to the housing, the inner end of the cylinder being connected to the filter interior and the outer end of the cylinder being connected to the first annular chamber portion, a piston in the cylinder and movable by differentials of fluid pressures in said inner and outer ends to selected positions within the cylinder, electrical contact means carried by the cylinder and engageable by an outer peripheral surface of the piston to establish electric circuits when the piston is at said selected positions, and indicating means actuated by said electric circuits to indicate the position of said piston relative to said selected positions.

2. The device of claim 1 in which said outer peripheral surface of said piston has a slide fit within said cylinder to prevent appreciable flow of fluid through the cylinder when the piston is in certain of said selected positions, and said piston having substantially its entire area exposed to fluid pressure at the inner end of the piston in all positions of the latter.

3. The device of claim 1 in which there is a third housing removably attached to said second housing and carrying said indicating means whereby said second and third housings may be removed as a unit for servicing the further element and piston and said third housing may be removed separately from the second housing for servicing said indicating means and also for mounting the indicating means at a location remote from said second housing.

4. A filter device comprising a first housing member havang an inlet and an outlet with a chamber therebetween and with an opening connected to the chamber, a hollow filter element in the chamber having its interior connected to the inlet and its exterior spaced from the chamber wall to provide a first annular chamber portion exterior of the element, said first chamber portion being connected to the outlet, a second housing removably attached to the first housing and extending across the opening to close the same, said second housing having a cup shaped cylinder depending therefrom into the chamber and engaging the filter element to hold it in a fixed position therein, the cylinder being radially spaced from the wall of said chamber to form a second annular chamber portion that is connected to the first annular chamber portion, the inner end of the cylinder being connected to the filter element interior, passage means through a side wall of the outer end of the cylinder connecting said outer end with the second annular chamber portion, a piston in the cylinder and urged by a spring toward an inner position against a stop in the cylinder, said piston being movable to other positions within the cylinder by differentials of fluid pressures in said inner and outer ends, said piston having a slide fit within the cylinder to prevent appreciable flow of fluid between said inner and outer ends, and said piston being outwardly of said passage means in an outer one of said selected positions whereby to connect said passage means with the inner end of said cylinder to permit bypassing flow of fluid from the interior of the element to said outlet.

5. The device of claim 4 in which said passage means includes portions spaced apart a sufficient distance to prevent complete blocking thereof by the piston as the piston moves toward said outer position and thereby prevent fluid lock in said cylinder outer portion.