WO1999025974A1

WO1999025974A1 - Restriction indicator for air cleaners

Info

Publication number: WO1999025974A1
Application number: PCT/US1998/024188
Authority: WO
Inventors: Larry R. Nepsund
Original assignee: Donaldson Company, Inc.
Priority date: 1997-11-14
Filing date: 1998-11-13
Publication date: 1999-05-27
Also published as: AU1585099A

Abstract

A restriction indicator for an air cleaner of an internal combustion engine. A bellows-type diaphragm is biased toward a retracted position by a first end of a compression spring. A calibration wheel threadingly engaging the housing supports a second end of the compression spring, such that the restriction indicator can be calibrated by rotation of the calibration wheel. An end of the compression spring is seated on a slanted seating surface so that a plunger is pushed off-center to engage a latch and lock the restriction indicator. Two arrangements of flow restricting orifices in the indicator are described which are for the purpose of dampening pressure spikes which can cause premature indication of a restriction.

Description

RESTRICTION INDICATOR FOR AIR CLEANERS

Field of the Invention This invention relates generally to restriction indicators for air cleaner systems, and more particularly to a restriction indicator having an arrangement for preventing the premature indication of a restriction.

Background of the Invention Restriction indicators provide a signal indicating when it is necessary to service the air cleaner of an internal combustion engine. They typically are connected to the air outlet of the air cleaner upstream of the intake of the engine. Most mechanical restriction indicators employ a bellows-type diaphragm vented to the atmosphere, which is resisted from expanding by a compression spring. As the air cleaner becomes more contaminated, the differential pressure between the "atmospheric"/high pressure side and the "negative'Vlow pressure side of the restriction indicator increases, thereby causing the diaphragm to expand. When the differential pressure has reached a certain level, the diaphragm typically becomes locked in an expanded position, and a constant warning signal is provided to the user that the air cleaner should be serviced. An example of such prior art restriction indicators is shown in U.S. Patent No. 3,443,365.

A significant concern with restriction indicators is the accuracy with which they indicate that a particular differential pressure has been reached. Restriction indicators are designed to provide a warning indication at a specific design pressure differential. It is important that they are accurate because improper indication would result in the air cleaner being serviced earlier or later than intended. It is difficult, however, to consistently manufacture accurate restriction indicators due to the variability of the component parts which make up the assembly. Component parts such as the spring, diaphragm, housing and locking mechanism, even when manufactured to close tolerances, can affect the accuracy of the indicator. Current designs, however, do not provide a mechanism for calibrating and adjusting the restriction indicator to account for these manufacturing variations.

Another problem associated with restriction indicators is providing a locking mechanism which will consistently lock and release after repeated use. In many designs, the locking mechanism includes a resettable plunger which engages a latch to lock the diaphragm in an expanded warning position. An example of this is shown by the '365 patent, in which the plunger is bent to engage the latch off-center.

Another problem is that restriction indicators can, under certain conditions, prematurely indicate that it is time to change the filter. This is typically caused by pulses created by the downstroke of pistons in the engine or, in high powered vehicles such as a CORVETTE, pressure surges created by quickly releasing the accelerator or downshifting. Unless the low pressure chamber of the indicator is insulated from such phenomena, the device can indicate that a filter change is needed when it is not. Although it is known to employ a pressure pulse dampener having an orifice separate from the restriction indicator, it is not known to incorporate such a device in the indicator itself.

What has been needed is a restriction indicator for air cleaner systems with a simple mechanism for permitting calibration to adjust for manufacturing inconsistencies. What has also been needed is a simple mechanism for locking a plunger in a restriction indicator. What has also been needed is an arrangement in the indicator for precluding the premature indication of a restriction due to pressure spikes that can occur.

Summary of the Invention

According to the present invention, a restriction indicator for an air cleaner system is provided.

In one aspect of the invention, the restriction indicator comprises a housing having high and low pressure chambers. The high pressure chamber is in communication with an inlet and the low pressure chamber is in communication with an outlet of the housing. A bellows-like diaphragm in the housing generally defines the high pressure chamber, and is moveable between expanded and retracted positions. A compression spring in the low pressure chamber has a first end biasing the diaphragm toward the retracted position. A mechanism cooperates with the diaphragm and compression spring to indicate when the diaphragm is in the expanded position. A calibration wheel supports a second end of the compression spring and has a portion which threadingly engages the housing. The threaded portion of the calibration wheel is rotatable so that a biasing force of the spring against the diaphragm can be varied, thereby permitting calibration of the movement of the diaphragm to its expanded position at a predetermined differential between the high and low pressure chambers.

In another aspect of the invention, an adjustable restriction indicator comprises a housing having high and low pressure chambers. The high pressure chamber is in communication with an inlet and the low pressure chamber is in communication with an outlet of the housing. A bellows-like diaphragm in the housing separates the chambers, and is moveable between expanded and retracted positions in response to pressure differences between the chambers. A compression spring in the low pressure chamber has a first end biasing the diaphragm toward the retracted position. A platform supports a second end of the compression spring and has a portion which threadingly engages the housing. The threaded portion of the platform is rotatable so that a biasing force of the spring against the diaphragm can be varied. In another aspect of the invention, the invention comprises an improvement in restriction indicators of the type where an expandable bellows-like diaphragm is biased by a compression spring toward a retracted position, and a resettable plunger engages a latch to lock the diaphragm in an expanded warning position. A member of the restriction indicator includes a slanted seating surface on which an end of the compression spring is seated. When the diaphragm expands to the expanded warning position, the spring pushes the plunger off-center to engage the latch.

In another aspect of the invention, a restriction indicator comprises a housing having first and second chambers separated by a diaphragm. The first chamber fluidly communicates with an outlet. A connector proximate the outlet is adapted for sealingly connecting the restriction indicator to the air cleaner system, thereby placing the first chamber in communication with the air cleaner system. A member in the housing has an orifice generally isolating the first chamber from the air cleaner system. The orifice is sized and configured to reduce the transmission of pressure changes from the air cleaner system to the first chamber.

In yet another aspect of the invention, a restriction indicator comprises a housing having a chamber defined therein. The chamber is fluidly connected to the air cleaner system. A mechanism in the housing dampens the transmission of changes in pressure from the air cleaner system to the chamber, thereby preventing the premature indication of a restriction.

These and other advantages and features of novelty that characterize the invention are pointed out with particularity in the claims annexed hereto. However, for a better understanding of the invention and its advantages, reference should be made to the drawings which form a further part hereof, and to the accompanying descriptive matter in which there is illustrated and described a preferred embodiment of the invention.

Brief Description of the Figures Figure 1 is a cross-sectional view of a restriction indicator according to the present invention, with the indicator in a non- warning position;

Figure 2 is a cross-sectional view of the restriction indicator shown in Figure 1, with the indicator in a warning position; and Figure 3 is a cross-sectional view of the restriction indicator shown in Figure 2, as viewed generally from section 3-3.

Detailed Description of the Preferred Embodiment Referring now to the drawings wherein like numerals designate like parts, a restriction indicator according to the present invention is shown in Figures 1- 3. The restriction indicator of the present invention can be used in conjunction with a variety of air cleaner systems for internal combustion engines. In the preferred arrangement, restriction indicator 10 is connected to a tubular member at the outlet of the air cleaner upstream of the intake of the engine, not shown. Restriction indicator 10 is inserted into an aperture of the tubular member, with a rubber grommet (not shown) positioned around barb 16 to provide a press fit seal in the area between annular rings 18.

Referring to Figure 1, restriction indicator 10 comprises housing 12 including casing 14 and cap 20 enclosing the open end of casing 14. Cap 20 is releasably connected to casing 14 by means of ramped ridge 15 which is snap fit into channel 21 of cap 20. Defined within housing 12 are high 30 and low 32 pressure chambers. High pressure chamber 30 is in communication with the atmosphere via an inlet 31 defined by three apertures 22 in cap 20 spaced at 120° intervals. Low pressure chamber 32 is in communication with an outlet 33 formed in barb 16 which in turn is in communication with the negative pressure side of the air cleaner, not shown.

Expandable diaphragm 40 generally defines high pressure chamber 30, which enlarges as diaphragm 40 expands. It is said herein that diaphragm 40 "generally" defines high pressure chamber 30 because chamber 30 also includes portions of the housing between the open end of diaphragm 40 and inlet 31. It will be understood that this area could be larger or smaller depending on the design. Diaphragm 40 is a flexible, expandable bellows-type diaphragm. It will be understood that a variety of diaphragms with similar characteristics could be employed within the principles of the invention. Diaphragm 40 includes lip 41 which is compressed between retainer 60 and a shoulder of casing 14, with cap 20 pushing downwardly on retainer 60. Interposed between cap 20 and retainer 60 is an annular filter 25 in recess 24 of cap 20. Filter 25 is made of DACRON polyester fiber or the like and prevents contaminants from entering high pressure chamber 30. Compression spring 45 biases diaphragm 40 toward a retracted position, as for example the position shown in Figure 1. Figure 2 shows diaphragm 40 in an expanded and locked position, with spring 45 being compressed by diaphragm 40. Spring 45 is seated as its upper end 46 with seating surface 72 of signal and at its lower end 48 with seating surface 53 of calibration wheel 50.

Diaphragm 40 is connected to signal 70 by means of plunger 63 which is snap fit into a corresponding opening 74 in signal 70. Base 42 of diaphragm 40 is held and sealed between plate 64 of plunger 63 and signal 70. A raised portion 43 of base 42 assures proper sealing.

Signal 70 moves downwardly and upwardly with the expansion and retraction of diaphragm 40. Outer screen 76 of signal 70 is visible through casing 14, which is transparent, in the portion forming a window 13 between the lower end of cap 20 and opaque covering 11 on casing 14. Alternatively, opaque covering 11 could be removed. Screen 76 is color coded and includes the words "CHANGE AIR FILTER," becoming visible through window 13 when diaphragm 40 is in its expanded position, as shown in Figure 2. Signal 70 also includes tab 71 used to align with apertures 61 in retainer 60 for consistent assembly. Restriction indicator 10 includes a locking assembly 69 which is largely known in prior designs. Although a locking mechanism is not absolutely necessary, it is preferable to provide a constant indication that the design pressure differential has been reached, so that a warning is provided when the engine is not operating. Locking mechanism 69 includes plunger 63 connected to move with signal 70 and with base 42 of diaphragm 40, and three circumferentially spaced latches 62 extending downwardly from retainer 60, best shown in Figure 3. Referring to Figure 2, when diaphragm 40 has expanded to its expanded position, plunger 63 is pushed off-center so that flange 65 of plunger 63 engages with latch 62, thereby locking diaphragm 40 and signal 70 in a warning position. Resetting the restriction indicator 10 is accomplished by manually depressing release button 67. Release button 67 has three fingers 68 which extend downwardly into three corresponding slots 66 between flanges 65, as shown in Figure 3. Fingers 68 and slots 66 are constructed to guide fingers 68 inwardly to recenter plunger 63 as release button 67 is depressed, thereby releasing plunger 63 from latch 62 and returning diaphragm 40 to its retracted position under the force of spring 45. It will be appreciated that the locking and resetting mechanisms could be constructed in a number of other ways.

A novel aspect of locking mechanism 69 is the slanted spring seating surface 72 on signal 70. Slanted seating surface 72 causes plunger 63 to be pushed off-center to securely engage latch 62. While slanted seating surface 72 is on signal 70 at upper end 46 of spring 45, it will be understood that the slanted surface could be on some other member of the device, and lower end 48 of spring 45 or both ends 46, 48 could be seated on a slanted surface. In the preferred arrangement, a single slanted seating surface 72 having an angle of approximately 15 degrees is employed. Slant angles of between 5° and 20° could also be beneficially employed. Spring 45 is of an appropriate strength and, when not deformed by slanted seating surface 72, is flat (not slanted) at both ends 46, 48. To ensure proper and consistent seating of spring 45 at upper end 46, a bent axial projection 47 of spring 45 is inserted into aperture 73 of seating surface 72.

Calibration wheel 50 is provided to permit calibration of restriction indicator 10 by adjusting the biasing force of spring 45 against diaphragm 40. Calibration wheel 50, which defines a platform, includes plate 52 supporting spring 45, and shaft 54 extending downwardly into barb 16 of housing 12. Shaft 54 has external threads 55 which engage a corresponding internal thread 17 of barb 16. It will be appreciated that calibration wheel could be configured in a number of other ways within the principles of the invention, as for example with a plate having external threads engaging an inner wall of the housing. Also, while the preferred calibration wheel 50 is molded as a single part, it could comprise two or more parts, as for example a stationery plate rotatably connected to a threaded shaft.

Communication between low pressure chamber 32 and outlet 33 is provided by central passage 59 of calibration wheel 50, which includes orifice 56 and first 57 and second 58 portions. Orifice 56 is sized and configured to reduce the transmission of pressure pulses from the engine intake to low pressure chamber 32, which can cause premature restriction indication. The diameter of the straight portion of orifice 56 is .045 inches. The tapered portion is for the purpose of making molding of the plastic part easier (the pin used to form the whole is less likely to shear). Second portion 58 of passage 59 is shaped hexagonally in cross section to receive an alien wrench (not shown) for threadingly rotating calibration wheel 50.

Shaft 54 of calibration wheel 50 is provided with two flexible ears extending radially outwardly. When calibration wheel 50 is rotated, ears 51 "ratchet" against the inner wall of barb 16, also hexagonally shaped, and lock into position in two of six spaced slots 66 in barb 16. This prevents unintended rotation of calibration wheel 50, which could affect the calibration.

Disk 80 with orifice 81 can be added for applications where large pressure spikes can occur. While orifice 56 of calibration wheel 50 will provide some dampening effect, a smaller orifice is preferred. Orifice 81 of disk 80 is accordingly 0.014 inches in diameter, but a diameter anywhere between .001 and .100 inches would provide some beneficial effect. Orifice 81 is also tapered to ease molding. Disk 80 is pressed fit into barb 16, and then the bottom of barb 16 is heat curled over it to hold it in place. This seals disk 80 to outlet 33 so that all air must pass through orifice 81 from chamber 32 (unlike orifice 56 in calibration wheel 50 because threads 55, 17 do not create a complete seal).

Individual restriction indicators are calibrated as follows. A weight corresponding to the design pressure differential (in this case approximately 20 inches of water) is placed on the top of plunger 63. The calibration wheel 50 is then rotated counterclockwise with an alien wrench until the plunger is lowered to a set point. The restriction indicator, now calibrated for improved accuracy, is ready to go into service.

It should be understood that the present invention is not limited to the preferred embodiment discussed above, which is illustrative only. Changes may be made in detail, especially in matters of shape, size, arrangement of parts, or material of components within the principles of the invention, to the full extent indicated by the broad general meanings of the terms in which the appended claims are expressed.

Claims

WHAT IS CLAIMED IS:

1. A restriction indicator for an air cleaner system, comprising:

(a) a housing having first and second chambers separated by a diaphragm, said first chamber fluidly communicating with an outlet;

(b) a connector proximate said outlet adapted for sealingly connecting said restriction indicator to the air cleaner system, thereby placing said first chamber in fluid communication with the air cleaner system; and

(c) a member in said housing having an orifice generally isolating said first chamber from the air cleaner system, said orifice being sized and configured to reduce the transmission of pressure changes from the air cleaner system to said first chamber.

2. A restriction indicator according to claim 1, wherein said orifice is proximate said outlet.

3. A restriction indicator according to claim 1 , wherein said member is generally disk shaped.

4. A restriction indicator according to claim 1 , wherein said member is sealed within said connector.

5. A restriction indicator according to claim 4, wherein said member is pressed fit into corresponding structure in said connector.

6. A restriction indicator according to claim 1, wherein said member extends at least partially into said connector and has a passage providing fluid communication between said orifice and said outlet.

7. A restriction indicator according to claim 1 , wherein said member is plastic.

8. A restriction indicator according to claim 1, wherein said orifice includes a tapered portion.

9. A restriction indicator according to claim 1 , wherein a diameter of said orifice is between .001 and .100 inches.

10. A restriction indicator according to claim 9, wherein said diameter is between .004 and .024 inches.

11. A restriction indicator for an air cleaner system, comprising: (a) a housing having a chamber defined therein;

(b) means for fluidly connecting said chamber to the air cleaner system; and

(c) means in said housing for dampening the transmission of changes in pressure from the air cleaner system to said chamber, thereby preventing the premature indication of a restriction.

12. A restriction indicator according to claim 11, wherein said dampening means comprise a member having an orifice therein.

13. A restriction indicator according to claim 12, wherein said member is proximate an outlet of said housing.

14. A restriction indicator according to claim 12, wherein said member is generally disk shaped.

15. A restriction indicator according to claim 12, wherein said member is sealed within said housing.

16. A restriction indicator according to claim 12, wherein said member extends at least partially into a connector of said housing and has a passage providing fluid communication between said orifice and an outlet of said housing.

17. A restriction indicator according to claim 12, wherein said member is plastic.

18. A restriction indicator according to claim 12, wherein said orifice includes a tapered portion.

19. A restriction indicator according to claim 12, wherein a diameter of said orifice is between .001 and .100 inches.

20. A restriction indicator according to claim 19, wherein said diameter is between .004 and .024 inches.