Two stage gauge with electrical signal output

Details Two stage gauge with electrical signal output Two stage gauge with electrical signal output

1999-06-25

2001-10-23

Hofsass, Jeffery (Department: 2632)

Communications: electrical

Land vehicle alarms or indicators

Internal alarm or indicator responsive to a condition of the...

C340S607000, C340S611000, C116S268000, C116SDIG002

Reexamination Certificate

active

06307466

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates generally to a mechanical filter gauge for determining the filtering capability of a vehicle filter. Specifically, the present invention relates to a mechanical gauge for measuring the functionality of a vehicle's air filter and providing a related electrical signal at an output.
Air filter restriction gauges are used in connection with an air filter for internal combustion engines. These devices typically sense the level of airflow restriction, and then indicate the level of restriction by locking itself in position. When the air filter has become so loaded with contaminants that the supply of air required by the engine for its operating efficiency is not being drawn through the filter, the gauge will indicate this and thus alert the operator that the filter requires cleaning or replacement. Some existing devices also lock themselves in various positions to provide a continuous indication as to how much useful life remains in the air filter before it should be cleaned or changed.
The use of a gauge to monitor the filtering ability of a vehicle's air filter is known in the art. Earlier patents in this area include U.S. Pat. No. 4,369,728, issued to Nelson on Jan. 25, 1983, and U.S. Pat. No. 4,445,456, issued to Nelson on May 1, 1984. These devices provided a visual display to the users or maintenance personnel. They did not have provisions to output an electrical signal indicative of the gauge's status.
By including an electrical component to the gauge, an indicator light within the cab of the vehicle can be added. The electrical component can simply be a switch which opens or closes when predetermined conditions are met. A dashboard indicator light could then be switched appropriately. However, the signal in the vehicle and the gauge near the engine would not always agree with each other using these prior art devices. Further, the dashboard light would not always remain on until the filter was serviced and the gauge reset. Also, as disclosed, these switches were relatively expensive to manufacture and assemble. The dashboard light signal could sometimes light before the gauge actually reached “redline,” or the point at which the air filter required replacement. Further, the dashboard light signal could flicker or not remain lit after the gauge had reached redline. The mere presence of the gauge and dashboard indicator will in most cases cause the driver of the vehicle to rely on the signal being given. However, if a signal is unclear, or gives a false indication that the filter is not yet in need of replacement, serious engine damage could result.
Once a clean and predictable signal could be developed as an output from the gauge, this signal could also be input to a computer control system or system controller to coordinate many functions. For example, this could provide an indication of an engine's operating conditions.
As mentioned above, several air filter restriction indicator gauges have been available for quite some time. Initially, these indicator gauges were simply a single stage type gauge where a warning button would pop once a predetermined restriction level was achieved. These gauges were phased out in favor of the incremental type gauges. The pop-up type gauges were not believed to be reliable and typically not trusted. The incremental type gauges would display an indication of the amount of filter left, thus would provide more reliable and believable information to the users. However, again as mentioned, none of these incremental gauges included reliable switching indicators which could be used to generate displays or to feed a system controller. If input to the system controller, even a single stage gauge is valuable as this provides meaningful information to the controller. Further, even a gauge which does not lock after predetermined levels nor requires manual resetting is provided, beneficial information can be measured and tracked.
Additionally, prior art indicators have not always been easy to fully reset, sometimes resulting in a gauge that may give a false, premature signal that an air filter requires replacement. This may in turn result in unnecessary filter maintenance.
SUMMARY OF THE INVENTION
The switch gauge of the present invention measures the performance of the filter and signals when the air filter of an internal combustion engine requires servicing or replacement. The measurement is accomplished by monitoring the vacuum in the air intake system of the vehicle. The level of vacuum achieved during engine operation is indicative of the air filter's condition. The device can gradually sense the status of the filter, from a clean condition to a dirty filter condition.
In the filter gauge of the present invention, a vacuum level of a predetermined level has been reached, a switch within the internal sensing chamber of the gauge is actuated. The switch can either be maintained or locked in this on position, even after the engine has been shut off, or the switch can be released at engine shut off. Stated alternatively, in a first configuration, the gauge of the present invention locks in a “set” condition after the predetermined level of vacuum has been achieved. When this lock takes place, the switch is maintained in a closed configuration. Alternatively, in another embodiment, the switch is only actuated when the engine is operating at the predetermined vacuum level. When the engine is subsequently shut off, the switch changes its condition. In each of these cases, the information can be used to alert the user, or to provide valuable control information to a system controller.
An object of the invention is to provide a gauge for indicating that an air filter for a vehicle with an internal combustion engine requires replacement.
It is a further object of the invention to provide such a gauge that is easily reset after each filter change.
It is another object of the present invention to provide a device which produces a signal indicative of whether or not a predetermined vacuum level has been achieved. This signal can then be used to alert the user that the filter must be replaced. This information can be provided to the user either via a warning light placed on the dash, or through an overall control system which monitors and coordinates the operations of the vehicle.
It is an additional object of the present invention to provide a device which produces a signal indicating when the engine is operating at a predetermined level of restriction in the air filter. This signal will maintain a certain condition as long as the engine is running and the predetermined vacuum level is maintained. When the engine is shut off, or the vacuum level is no longer above the predetermined amount, the signal will then change states, indicating that this operating condition no longer exists for whichever reason. These signals are easily transmitted to a overall engine controller system.
It is a further object of the present invention to provide a system which produces a constant signal once a predetermined vacuum level has been achieved. This signal will then remain the same until it is reset either manually or via a coordinated computer control reset.
It is yet another object of the present invention to provide a device which will produce both a visual and electrical indication that a predetermined vacuum level has been achieved. By placing a window in the housing, and appropriately configuring an indicator device, the visual indication is achieved. The visual indicator will not be seen when the device is below the predetermined level, however the indicator will be seen when the predetermined vacuum level has been achieved.


REFERENCES:
patent: 2946222 (1960-07-01), Husjack
patent: 3594745 (1971-07-01), Nickels
patent: 3654414 (1972-04-01), Kudlaty
patent: 3696666 (1972-10-01), Johnson et al.
patent: 3939457 (1976-02-01), Nelson
patent: 3963891 (1976-06-01), De Mogondeaux
patent: 4033733 (1977-07-01), Nelson
patent: 4171962 (1979-10-01), Kippel et al.
patent: 4183029 (1980-01-01), Isayam

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