AN OPTICAL AUTOMOTIVE SENSOR

FIELD OF THE INVENTION:

This invention relates to an automotive sensor.

BACKGROUND OF INVENTION:

Engines involve a large number of components with a limited service life. It can be difficult to judge when service life is near expiry and replacement of a component is required. For example, two or three wheeled automotive vehicles typically have an air cleaner or an air intake filter for cleaning the air before it enters the engine. Without an air cleaner or filter, dirt will enter the engine and degrade the engine over time. Normally, the air filter consists of a filtering element which restricts entry of dust/dirt particles and allows clean air to enter into engine. Many air cleaners and filters over a period of time due to dirt/dust entrapped or clogged into the filter or cleaning element, decrease the amount of air that can enter into the engine, thus causing the engine's power output to decrease. This also causes lower fuel mileage and higher emissions causing environmental pollution. Therefore it is important to replace the filtering element over a period of time. Known air intake filters include, foam, oiled foam, oiled fabric, and dry paper as filter element. Dust and dirt clog the pores in the filter element, decreasing the airflow and decreasing the engine performance as mentioned above.

It is very difficult for the rider or owner of the vehicle to judge the performance and operability of the air filter. Also, it is difficult to remember the replacement frequency of air filter element as recommended by manufacturer. Even if rider checks the filter, it is difficult to judge whether the filter element is in good condition or it is required to be replaced. Hence the rider or owner of vehicle may continue with an inefficient filter clogged with dirt and dust thereby causing the above-mentioned problems or may replace the filter element thereby incurring unnecessary cost for it. The same sorts of problems may arise with other engine components or elements.

OBJECT OF INVENTION :

It is the object of the present invention to provide an automotive sensor which assists assessment of operability of engine components, such as air filters.

STATEMENT OF INVENTION:

With this object in view, the invention provides an automotive sensor for measuring operability of an engine element comprising:

(a) a light transmitter for directing light at the engine element;

(b) a light receiver for receiving light transmitted through, or reflected from, the engine element;

(c) an electrical circuit for relating an amount of transmitted or reflected light to a degree of operability of the engine element; and

(d) an output means connected to the electrical circuit;

Preferably, the output means is an indicator means connected to the electrical circuit, wherein the indicator means provides a signal corresponding with the measured degree of operability of the engine element.

Preferably, the output means provides signal to the electronic engine control system corresponding to the measured degree of operability of the engine element.

Preferably, the electronic engine control system regulates the fueling rate, to correct the air fuel ratio for proper engine operation.

Preferably, the fuel delivery system is a simple fuel injector, the operation of which is controlled by engine control system.

The sensor may be applied to determination of degree of physical operability of the engine element. For example, the sensor may be applied to

determine whether an air filter element has become too obstructed to operate effectively.

The intensity of reflected light, rather than transmitted light, may be preferred as a basis for determining the degree of operability or serviceability of the engine element. For example, where the engine element is an air filter element, a clean filter may be reflective whereas a clogged or dirty filter is distinctively less reflective. This difference in the degree of reflected light, which may be converted to a voltage signal, allows determination to be made as to the degree of operability or serviceability of the air filter. If reflectance is used, light transmitter and emitter may be located on the same side of the engine element, for example, the air filter. This allows simpler and more compact arrangement. If light transmission is used instead, both emitter and receiver would need to be located on either side of the engine element.

The electrical circuit preferably comprises a comparator to compare the values of light signals received by the light receiver, with a predetermined range of values and activate an indicating device observable by an operator in case of the value of said received signal exceeds or goes beyond a predetermined range of values. That is, the indicator device may provide information as to whether the engine element is operable or not operable. The indicator device may also provide indications as to the remaining service life of the engine element or the next likely replacement date. For example, the indicator device may take the form of a warning light on a vehicle dash panel that illuminates when degree of operability falls below an acceptable level. Alternatively, the indicator device may take the form of a light which remains illuminated as long as the sensor determines that the engine element is in serviceable condition. The indicator light may be coupled with an audible alarm for greater impact.

The light receiver, of photosensitive material, may communicate with the comparator through at least one amplifying means. The comparator may be pre-calibrated with respect to color of a clean air filter element and color of a clogged filter element due for replacement, these colours being related to

different levels of light reflectance. The circuit may be arranged to correlate the amount of light received to the degree of operability of the engine element along a continuum of the comparator.

-The transmitter may be an infrared light emitter, such as a light emitting diode, and the receiver may be a photo sensitive receiver. -Preferably, the transmitter and receiver are located in one unit though in different compartments, each being provided with a guiding channel. However, the transmitter and receiver may be located in different vertical planes to prevent cross - signaling and interference.

The automotive sensor may be mounted on a housing of the engine element. For example, the sensor may be mounted on the air filter housing.

Advantageously, the housing in which the sensor is to be mounted and/or the particular orientation of the sensor, is selected such that if the engine element is not present, a low operability signal is generated by the sensor. In the example of the engine element being an air filter, if the air filter was accidentally removed or left out of its housing, the colour of the housing and/or the location of the senor would be such that a low reflectivity signal (that is, a fully clogged or blocked filter) was generated and thereby alert the operator to a problem.

Further, the engine element being an air filter, may be provided with a wire mesh of suitable colour distinguished from that of the air filter element, so that the sensor would advantageously measure the operability of the engine element .

While the sensor is located to determine the operability of one engine element, the signals from the sensor may be used to diagnose other possible engine operating conditions and problems of serviceability of other engine components. For example, early clogging of an air filter may perhaps indicate problems with other engine components.

The output means may provide a signal from the automotive sensor to be used as a control signal which may be in turn be used as an input for a control unit for an engine. Sensing of the operability of the engine component, for example an air filter, may - by providing early warning of potential failure or un-serviceability - prevent engine malfunctions or performance degradation.

In another aspect of the invention, there is provided a method for measuring operability of an engine element comprising the steps of:

(a) directing light at the engine element from a light transmitter;

(b) receiving light transmitted through, or reflected from, the engine element by a light receiver;

(c) measuring the amount of transmitted or reflected light; and

(d) relating the amount of transmitted or reflected light to a degree of operability of the engine element; and providing a signal output corresponding with the measured degree of operability of the engine element.

The method may be applied to determine operability of a number of engine elements. In one embodiment, the method is applied to determination of the operability of an air filter. The method may be used as part of an engine control strategy or as a diagnostic to alert a vehicle operator to potential engine malfunctions. In this way, the operator may take requisite service action to avoid the malfunction.

The signal output may be used as an input to an engine management system. Fueling computations in a typical engine management system are based on certain necessary or essential inputs, some of which are:

1. Throttle position and engine speed or

2. Throttle position and intake manifold pressure together with engine speed or

3. Intake manifold pressure and engine speed.

It is possible to achieve further refinements and accuracy based on inputs such as intake air temperature, engine temperature, roll over sensor, air pressure sensor or air fuel ratio sensor.

In the present embodiment of the invention, the inputs from the sensor which will vary depending upon the condition of the air filter foam, may be used to further refine fuelling rate.

This will be useful in typical engine control systems where the calibration for fuelling rate based on intake manifold air pressure and engine speed cannot be fine tuned owing to memory or software constraints. While the engine control system computes interpolation for the intermediate calibration points, the input from the sensing element, as described in this invention, may be used in refining the fuelling rate. Thus, as signal varies with operability of the engine element, an engine management strategy may be correspondingly varied. For example, as an air filter becomes contaminated, it may lead to a reduced air flow rate to the engine and to an over rich air fuel ratio. Thus the fueling rate delivered to the engine may be reduced to correct the air fuel ratio for proper engine operation.

The automotive sensor and methods of the invention are applicable to a variety of engines. It is applicable to air breathing internal combustion engines whether used in 2, 3 or 4 wheeled vehicles. The reference to the "light" is intended to include a reference to visible and/or non-visible light.

DETAILED DESCRIPTION OF INVENTION:

The following is detailed description of a preferred embodiment of the invention made with reference to the accompanying drawings, in which: Figure 1 illustrates a block diagram of a sensor for sensing operability of an air filter element according to one embodiment of the invention. Figure 2 illustrates a mounting arrangement of sensing/detecting device for sensing operability of the air filter element.

Figure 3 illustrates details of sensing elements of the sensor device of Figure

2.

Figure 4 illustrates a block diagram of a sensor for feeding output to an engine control system to regulate fueling rate.

Referring to Figure 1 , there is shown an automotive sensor 30 used to assess degree of operability of an air filter 40, comprising an air filter element 12. The sensor 30 uses infra red light as diagnostic medium. To this end, sensor 30 includes an infrared light transmitter 1 connected to a power supply source battery 2 through a power supply regulator 3. Transmitter 1 may be in the form of a light emitting diode (LED). A regulator 3 may be provided with a short circuit protection device. The infrared transmitter 1 is also connected to a pulse generator device 4 to emit infrared signals intermittently at a predetermined frequency. An infrared photosensitive receiver 5 is connected to a signal shaping circuit 6, which shapes the signal to a square wave eliminating spikes for proper voltage sensing in the comparator circuit, which is in turn connected to two stages of signal amplifiers or amplifying circuits marked as 7 and 8. The second signal amplifier 8 is connected to a comparator 9. The comparator output 10 is communicated to a malfunction indicator device or lamp 11 which may be fitted on a vehicle dashboard (not shown) and to fuel injector fueling rate control 14 (as depicted in Figure 4) in the engine control unit 23 (as depicted in Figure 4).

Figure 2 illustrating the mounting arrangement of the sensor 30, shows an air filter housing 15 having unclean air entry passage 18 and a clean air passage 21. The outer wall 22 of air filter housing 15 is provided with an opening 20, where a sensor device 17, comprising a transmitter 1 (Figure 3) and a photosensitive receive 5 (Figure 3) is mounted in a holder 16. A front portion of sensor device 17 is inserted into opening 20 so that the infrared light transmitter 1 (Figure 3) and photosensitive receiver 5 (Figure 3) face foam filtering element 12 fitted into the air filter 40. A rubber grommet 19 provided between the front portion of sensor device 17 and periphery of opening 20 to minimize damage and ensure rigid fixing of sensor device 17.

It can be observed from Figure 2 that the sensor device 17 is placed on an intake side of the air filter 40 so that sensing of the operability or service condition of filtering element 12 is achieved in an accurate manner.

Referring to Figure 3, which depicts a detailed sectional view of sensor device 17, the light transmitter 1 is provided with a channel 25 and the light receiver 5 is provided with a channel 26. The channels 25 and 26 are provided to avoid cross signaling between light transmitter 1 and light receiver 5, which could otherwise lead to erroneous results.

In use, infrared transmitter 1 transmits infrared rays/signals intermittently towards the filter element, that is, foam 12. The signals reflected back from the foam filter element 12 are received by infrared light receiver 5. The intensity of the reflected signal depends upon the color of the filter element 12. A highly reflective colour, such as white, indicates serviceability. As service life lengthens, the colour of the filter element 12 becomes less reflective and darker. Such a colour tends to favour absorption of light. The signals received by light receiver 5 are passed through two stages of amplification to convert the signals to a measurable value which can be related to a degree of operability or serviceability of the filtering element 12. The amplified signals are compared by the comparator 9 with a predetermined range of voltage.

The comparator 9 is pre-calibrated with reference color of a clean air filter element 12 and color of clogged air filter element 12 due for replacement in terms of voltage or any other parameter. The reflectivity of filter element depends upon its color, hence over a period of time as the filter element gets clogged with dust/dirt particles and its color changes. The change in color affects the reflectivity of filter element, which is sensed by the receiver and compared by the pre-calibrated comparator as mentioned above. Therefore when due to clogging and color change, the reflectivity of filter element reaches beyond a predetermined limit, the comparator out put gives a warning signal to rider to indicate that the filter element is due for replacement.

Advantageously, the housing in which the sensor is to be mounted and/or the particular orientation of the sensor, is selected such that if the air filter element is not present, a low operability signal is generated by the sensor. If the air filter was accidentally removed or left out of its housing, the colour of the housing and/or the location of the senor would be such that a low reflectivity signal (that is, a fully clogged or blocked filter) was generated and thereby alert the operator to a problem.

In case the If received light signals are not within a predetermined voltage range, the malfunction indicator lamp 11 is illuminated to give an alarm signal to the rider of the vehicle that replacement of filter element 12 is advised. Lamp 11 may be placed in the instrument console of vehicle for better visibility. The malfunction or warning lamp 11 may be coupled with a suitable buzzer or beeper to provide audible signal to rider.

Figure 3 also shows that the light receiver 5 is placed towards front rather than light emitter I .This assists better reception for the light signal reflected by the filter element 12 as reflected light signals may be weak.

Example

Sensor 30 is employed in a motorcycle wherein the supply voltage to infrared light emitter 1 is 5 volts. The filter element 12 is of white color. The comparator 9 is pre-calibrated with a reference color for a clean air filter element and the color of clogged air filter element due for replacement. Voltage is used as the diagnostic parameter. Comparator 9 compares the amplified received signals reflected by filter element 12 and if the value of a reflected light signal is more than 2.5 volt, lamp 11 is illuminated advising the rider to replace the filter element 12. In case the amplified received signal is less than 2.5 volts, the lamp 11 remains deactivated.

Modifications of the invention to the automotive sensor and method of the invention may be evident to the skilled reader of this disclosure. For example, the pre-calibrated values of comparator 9 and predetermined

voltage values for activating the indicating device may be varied depending, for example, upon colour of filter element, distance of sensing device from filter element. Further, the placement, shape of sensing device may be altered suitable to particular automobile. The visual or audible indication/alert to the rider may be in different forms. All such modifications are considered to be included in this application.