DESC:FIELD OF INVENTION

The present invention relates to a belt-tension detector in a belt-drive of an automobile engine, particularly a belt-tension detector for detecting and indicating belt slackness, more particularly a belt-tension detector for automatic detecting and indicating belt-slackness for advance warning to the driver to avoid belt-drive failure and thereby prevent engine seizure or failure of other important automobile sub-assemblies. The present invention also relates to a method for automatically detecting and indicating belt slackness in belt-drives of automotive engines

BACKGROUND OF THE INVENTION

In automotive vehicles, the engine failure or seizure is the most-dreaded phenomenon. It is generally believed that engine overheating is the main cause of such engine seizure. This is normally attributed to lack of water in the radiator, thereby it may cause engine overheating, leading to sudden engine seizure. However, there is another silent culprit frequently causing such engine seizure and which is normally overlooked, i.e. the belt-slackness or loosening in the belt-drive directly or indirectly connected to the engine pulley for running the alternator.

There are also few other important automobile sub-assemblies directly or indirectly connected to the engine pulley via belt-drives, e.g. timing belts, water-pump and air-conditioning unit, which may malfunction or function poorly, leading to other operational failures or customer dissatisfaction. However, the alternator remains the one of the most important belt-driven sub-assembly of an automobile, which needs to be operating flawlessly to prevent discharge of battery.

The alternator is the main source for the battery charging and in some vehicles, it is also used to measure the engine RPM. These alternators are driven using engine pulley through a belt. Over a period of vehicle operation, the belt expands/loosens due to its inherent properties and belt-slippage occurs.
Due to this belt slippage, the alternator rotates slowly and the alternator output is substantially affected, which in turn leads to poor charging and the engine RPM shown is also often incorrect.

In higher-end automobiles, there is an external belt tensioner for automatic tightening of the belt, whenever the belt gets loosened. But, such adjustments are only for a limited effect due to dimensional and other operational restrictions.

PRIOR ART

Present technology offers solutions for removing belt slackness by using automatic, radially adjustable pulley. However, this also has limitations in terms of the extent to which the pulley can be adjusted radially. Also, the operator of the vehicle is not aware of extent of pulley expansion, which further leads to engine seizure at a later stage.

For example, US8360908 discloses an expandable pulley comprising a plurality of adjacent segments, each segment being radially moveable, each segment slidingly engaged with a pin member, each pin member having an engagement with each segment such that each segment is moveable in a direction substantially at an angle (alpha) to a radial along each pin member, a moveable guide member engaged with each segment for spatially locating each segment with respect to another segment, a counterweight cooperatively connected to each segment and cooperatively engageable with each pin member, each counterweight exerting a force opposing a segment centripetal force, and each pin member connected to a hub.

An article entitled - “Belt slackness detection for the automobile system” by C. Sathian, B. Kumar and C. Raju published in Vol. 2, No. 1, March 2012 of Bonfring International Journal of Industrial Engineering and Management Science, which is available online [Link] has proposed to determine and indicate belt slackness to the automobile driver by using an apparatus consisting of a simple potentiometer usable as a voltage divider or a potential divider to obtain a manual adjustability.
However, there are limitations with this manual adjustable system as well, which includes packaging issue of the engine, i.e. accommodating the engine inside the engine cabinet due to addition of extra components viz. potentiometer and extra pulley.

Therefore, at present, there is no device or method and/or device, by which the belt-slackness in a belt-driven can be constantly monitored and indicated to the driver for preventing engine seizure, alternator malfunctioning as well as avoiding failure of other belt-driven sub-assemblies, e.g. timing belts, water pumps, air-conditioning unit etc.

DISADVANTAGES WITH THE PRIOR ART

It is possible to maintain the belt-tension in a belt-drive automatically by using a belt-tensioner, it is impossible to judge or ascertain as to at what stage the belt should be changed. Therefore, when the belt gets tear/cut-off suddenly, a partial or even a complete automobile malfunctioning occurs, which in turn leads to customer dissatisfaction.

Furthermore, the alternator rotates because of frictional force acting between the pulley and belt. Often, there is dust and mud deposition on the pulley and belt, which causes the pulley to wear-off after a certain period of time. This causes a variation in the rotating speed of the alternator, leading to higher and/or lower rotation of alternator than a designed speed. This also directly affects the efficiency of the alternator or reliability of the alternator, ultimately leading to malfunctioning of the engine. The same happens with other sub-assemblies running directly or indirectly on a belt-drive, which may also be impaired in their respective functioning.

Therefore, there is a long-felt and existing need for an arrangement and method for continuously monitoring, detecting and indicating belt slackness in a belt-drive, such as in an alternator, so as to check the serious impairments in the automobile functioning, e.g. engine seizure, non-efficient functioning of timing-belts, water pump, air-conditioner etc.
OBJECTS OF THE INVENTION

Some of the objects of the present invention - satisfied by at least one embodiment of the present invention - are as follows:

An object of the present invention is to provide a device for automatic and continuous monitoring of the belt-tension in a belt-drive of an automobile.

Another object of the present invention is to provide a device for automatic and continuous indication of the belt slackness to the driver of an automobile.

Still another object of the present invention is to provide a simple and low-cost automatic belt slackness monitoring and indication device without limitations.

Yet another object of the present invention is to provide an advance alert about belt slackness in belt-drives alert to the driver for timely action.

A further object of the present invention is to provide an automatic belt slackness monitoring and indication device for improved battery charging.

Still further object of the present invention is to provide an automatic belt slackness monitoring and indication device for improved reliability of the alternator.

These and other objects and advantages of the present invention will become more apparent from the following description when read with the accompanying figures of drawing, which are, however, not intended to limit the scope of the present invention in any way.

SUMMARY OF THE PRESENT INVENTION

In accordance with the present invention, there is provided a device for automatically detecting and indicating belt slackness in belt-drives of automotive engines, the device comprises:
• an ignition switch,
• alternator providing input signal of the frequency thereof,
• a crank/cam sensor for sensing the engine speed in revolutions per minute (rpm),
• a cluster controller (ECU) to convert the alternator frequency into engine speed in rpm and to calculate the actual engine speed available at the alternator,
• a comparator to compare actual engine speed calculated by the cluster controller with the engine speed sensed by the crank/cam sensor, and
• warning means to alert the automobile user for taking corrective action, if the actual engine speed available at the alternator is less than the engine speed sensed by the crank/cam sensor.

Typically, the comparator signals belt tension to be correct, when the actual engine speed available at the alternator as calculated by the cluster controller is equal to the engine speed sensed by the crank/cam sensor.

Typically, the comparator signals belt tension to be incorrect, when the actual engine speed available at the alternator as calculated by the cluster controller is less than the engine speed sensed by the crank/cam sensor by a predetermined value, the device initially alerts the vehicle driver that the belt-tension is not correct and remedial action should be taken.

Typically, the device sends signal to the cluster controller, if the actual engine speed available at the alternator as calculated by the cluster controller is more than the engine speed sensed by the crank/cam sensor by a value exceeding the predetermined value.

Typically, the device alerts the vehicle driver by means of a visual display.

Typically, the device alerts the vehicle driver by means of an audible alarm.

Typically, the device alerts the vehicle driver by means of a tell-tale indicator.

Typically, the device alerts the vehicle owner and the service station or the vehicle user to change the alternator pulley belt, if the actual engine speed available at the alternator as calculated by the cluster controller is less than the engine speed sensed by the crank/cam sensor by a value exceeding the predetermined value.

Typically, the device alerts the vehicle owner and the service station or the vehicle user by sending an SMS on the predefined mobile number of the vehicle owner and the service station or the vehicle user.

In accordance with the present invention, there is also provided a method for automatically detecting and indicating belt slackness in belt-drives of automotive engines, the method comprises the following steps:

• Supplying signal to the cluster controller (ECU) on switching on the vehicle ignition switch,

• Obtaining frequency input signal from the alternator and forwarding the same to the cluster controller (ECU),

• Obtaining rotational speed (rpm) of the engine by means of the crank/cam speed and forwarding to the same cluster controller (ECU),

• Converting the alternator frequency into the engine speed in rpm and calculating the engine speed actually available at the alternator by means of the cluster controller (ECU) and forwarding the same to the comparator,

• Comparing the engine speed actually available at the alternator as calculated in the cluster controller with the engine speed sensed by the crank/cam sensor,

• Signaling to the vehicle driver the belt tension to be correct, if the actual engine speed available at the alternator as calculated by the cluster controller is equal to the engine speed sensed by the crank/cam sensor,

• Alerting the vehicle driver by means of a visual display and/or audible alarm and/or a tell-tale indicator, if the actual engine speed available at the alternator calculated by the cluster controller is less by a predetermined value than the engine speed sensed by the crank/cam sensor, indicating to the vehicle driver that the belt-tension is not correct and remedial action should be taken, or sending a signal to the cluster controller, if the actual engine speed available at the alternator as calculated by the cluster controller is more than the engine speed sensed by the crank/cam sensor by a value exceeding the predetermined value, or

• Alerting the vehicle owner and the service station or the vehicle user by sending an SMS on the predefined mobile number to change the alternator pulley belt, if the actual engine speed available at the alternator as calculated by the cluster controller is less than the engine speed sensed by the crank/cam sensor by a value exceeding the predetermined value.

DESCRIPTION OF THE PRESENT INVENTION

To overcome above drawbacks, the present invention proposes a belt-tension monitoring and detecting device for automatic detection and indication of the belt slackness.

Thus, this device can give an advance warning to the vehicle driver, whereby a foreseeable belt-drive failure can be avoided. This device can effectively prevent engine seizure as well as a failure of other important sub-assemblies in the automobile.

Conventionally, the alternator and the engine respectively have a normal fixed pulley. The engine pulley mounted on the drive shaft rotates the alternator pulley via a belt. However, this normal pulley is replaced with an automatic radially adjustable pulley. Accordingly, on the belt getting loosened, the pulley will expand radially automatically and always retain the proper tension. The Pulley-Ratio to the Engine Speed and Alternator Speed is given as under:

PULLEY RATIO (C) = _ALTERNATOR SPEED_ = ___ENGINE PULLEY DIA___
ENGINE SPEED (RPM) ALTERNATOR PULLEY DIA

This pulley ratio C is calculated under certain predetermined conditions, such as belt tension and calibrated new pulley. The same is fed into microcontroller as the reference value.

The pulley ratio is used for calculating the engine speed from the alternator speed. The alternator speed is monitored continuously by the cluster controller through signal received from alternator W terminal. The engine RPM is continuously monitored by the controller through an engine speed sensor.

A ‘W’ terminal signal from the alternator is relayed to the controller. The controller calculates the engine RPM as under:

Alternator RPM = Alternator frequency*10.

Whenever the belt slackness increases, the pulley expands radially, the alternator speed varies, so the actual pulley ratio (it is continuously calculated by microcontroller using the pulley ratio formula) changes accordingly.

A logical computer programme stored in the controller / microcontroller executes a comparison of two engine speeds, i.e. the first engine speed calculated with reference pulley ratio and the second engine speed directly coming from the engine speed sensor and automatically gives a signal, e.g. display, warning, vibration etc. to the vehicle driver via steering or pedal, thus prompting the driver to check and correct the belt tension or belt condition of the belt/s running on the engine/alternator pulley.

a) For example, assuming that the expandable pulley is fixed on the alternator and that the engine speed obtained from the sensor is 1000 rpm and the Engine pulley diameter is 80 mm and the alternator pulley diameter is 40 mm, thereby giving a pulley ratio of 2 (80/40). This pulley ratio will be fed to the cluster controller to calculate the engine speed through the alternator speed, which is 2000 rpm. Now the controller converts the alternator speed into the corresponding engine speed by using the formula:

Alternator speed / 2 = 2000 /2 = 1000 RPM.

Here, the engine speed from sensor and the engine speed calculated by the controller using the alternator speed are both found to be equal. Hence it is concluded that the belt tension is correct.

b) The belt gets loosened due to belt-wear and the pulley expands radially to retain the specified belt-tension. Hence, the Alternator pulley diameter is changed to 45 mm, so the pulley ratio changes as under:

Engine pulley diameter / Alternator pulley diameter = 80 / 45 = 1.78

Now, due to change in the pulley ratio, the alternator rotates at 1780 rpm for the engine speed of 1000 rpm of obtained from the engine speed sensor. This change in pulley ratio is not known to the controller, thus it calculates the engine speed from the alternator speed fed with pulley ratio of 2.

Therefore, the calculated engine speed is:

1780 / 2 = 890 RPM

Here, the controller compares the calculated engine speed (890 rpm) to the engine speed received from the engine speed sensor (1000rpm). Since the calculated engine speed 890 rpm < engine speed 1000 rpm received from the engine speed sensor, the controller immediately adjusts this variation in the following stages:

If the calculated engine speed falls below the acceptable limit.

STAGE 1: The controller will alert the driver by alarm and indications/vibrations regarding the belt wear out.

STAGE 2: The controller will send the message to the owner and service center through telematics. So that the dealer will register regarding the miss usage and to change the belt immediately.

Generally, the alternator produces a certain frequency with respect to the engine speed. Whenever, the belt slip occurs due to belt slackness, the alternator speed reduces with respect to the engine speed and a lower frequency is produced, which can also be monitored by the instrument cluster. If the automatically expandable pulley is fixed on the engine shaft (which is driving the alternator), then in case of the belt becoming loose, the alternator speed increases. Similar to the above case, the controller monitors the speed up to an allowable limit, thereafter that it alerts the driver and sends him an sms.
The driver is immediately alerted by giving some indication on the instrument cluster to correct the belt tension. This way an effective, simple, low-cost and efficient belt-tension monitoring and detecting device is obtained.

For the vehicle in which there is no engine speed sensor, the acceptable value for a particular rpm, e.g. high idling speed is pre-programed. Whenever the customer desires to check the belt/pulley, only a calibration button is needed to be pressed and the engine is run at high idling speed, whereby the actual rpm is compared with the programmed rpm to indicate any existing abnormality.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will be briefly described with reference to the accompanying drawings, which include:

Figure 1 shows a typical alternator fitted with a pulley.

Figure 2 shows a typical single drive-belt used for running a number of accessories, e.g. alternator, water-pump and so on.

Figure 3 shows a flow chart of the process for automatically detecting the over-loose belt-tension by means of the device configured in accordance with the present invention.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS

In the following, different embodiments of the present invention will be described in more details with reference to the accompanying drawings without limiting the scope and ambit of the present invention in any way.

Figure 1 shows a typical alternator 10 fitted with a pulley 20 for generating electrical energy from engine shaft rotation when connected by a belt running on engine pulley (not shown).

Figure 2 shows a typical belt-drive consisting of a belt 30 running on an alternator pulley 20 and connected via an intermediate idle flat-pulley to another accessory, e.g. a water-pump 110 fitted with another pulley 120 on which this same belt is running. This way, a number of accessories, e.g. alternator, timing belts, water-pump, air-conditioner etc. may be driven by the same belt or different accessories may be driven by different belt-drives. Since alternator is the most crucial unit responsible for engine seizure (in common rail engine battery is very important for vehicle running), our focus is on automatic monitoring, detection and indication of alternator belt slackness.

If belt slackness at alternator is detected, this also has cascading effect on all other engine subassemblies in the relevant belt-drive, such as those running water pump and cam pulley.

Figure 3 shows a flow chart of the process for automatically detecting the over-loose belt-tension by means of the device configured in accordance with the present invention. It includes an alternator 10, a crank/cam speed sensor 20, an ignition switch 30, a cluster controller 40 for converting alternator frequency into engine speed, a comparator 50 to check, whether the calculated engine speed is less than the engine speed received from engine speed sensor or not. In case the alternator speed is less than the engine speed, an alert is issued at step 60 to the driver for tightening the belt tension. However, if the belt tension is not corrected, then respective alerts are issued at step 70 to the owner as well as to the customer care of the service station or to customer care via SMS.

Although, the exemplary embodiment shown here refers to belt-slackness in the alternator belt-drive, the present invention can be used in respect of any belt-drive, in which belt slackness is important factor to determine the reliability of its operation.

WORKING OF THE INVENTION

The automatic radial expanding pulley is directly assembled on the alternator or engine crank pulley, so that whenever the belt-tension is less than a predetermined value, i.e. shows any belt slackness, this expandable pulley automatically expands to overcome the belt slackness. When the belt-tension is within specified limits, the following ratio holds good:

ALTERNATOR SPEED (A) / ENGINE SPEED (B) = PULLEY RATIO (C)

This pulley ratio C is fed into the microcontroller as the reference value. Now, the alternator speed is monitored continuously by the controller/instrument cluster through signal received from alternator’s W terminal. Similarly, engine speed is monitored continuously by the controller/cluster through the signal received from speed sensor of engine (crank /cam).

When the belt loosens or there is belt slackness, then the pulley expands for automatic re-tensioning and the alternator speed decreases. Due to expansion, the alternator pulley diameter increases. This alternator speed is monitored by the microcontroller through the signals received from ‘W’ terminal of the alternator.

If the calculated engine speed after the pulley expansion goes below the acceptable limit, i.e. in a stage 1, the controller alerts the driver by issuing an alarm or giving an indication, such as flashing LED/s or generating vibrations on the steering or foot-pedals of the driver.

Alternatively, in a stage 2, the controller sends the message to the owner and service center through telematics, so that the dealer may register regarding the improper of the vehicle by the driver and vehicle will be allowed to run at idle RPM only.

On the other hand, when the automatic expandable pulley is fixed on engine shaft for driving the alternator, and on observing belt slackness, or belt getting loosened, the alternator speed increases.

Here also, the controller monitors the speed up to a permissible limit, once this limit is exceeded, the controller alerts the driver and send a sms in the same manner as described above.

TECHNICAL ADVANTAGES AND ECONOMIC SIGNIFICANCE

The device for Automatically detecting and indicating belt slackness in belt-drives of the engines configured in accordance with the present invention has the following advantages:

• User is timely alerted to change the belt/pulley of the alternator.

• Efficient charging is facilitated.

• Alternator reliability is enhanced.

Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, shall be understood to implies including a described element, integer or method step, or group of elements, integers or method steps, however, does not imply excluding any other element, integer or step, or group of elements, integers or method steps. In the claims and the description, the terms “containing” and “having” are used as linguistically neutral terminologies for the corresponding terms “comprising”.

The use of the expression “a”, “at least” or “at least one” shall imply using one or more elements or ingredients or quantities, as used in the embodiment of the disclosure in order to achieve one or more of the intended objects or results of the present invention. Furthermore, the use of the term “one” shall not exclude the plurality of such features and components described.

The description provided herein is purely by way of example and illustration. The various features and advantageous details are explained with reference to this non-limiting embodiment in the above description in accordance with the present invention.

The descriptions of well-known components and manufacturing and processing techniques are consciously omitted in this specification, so as not to unnecessarily obscure the specification. In the previously detailed description, different features have been summarized for improving the conclusiveness of the representation in one or more examples.
However, it should be understood that the above description is merely illustrative, but not limiting under any circumstances. It helps in covering all alternatives, modifications and equivalents of the different features and exemplary embodiments. Many other examples are directly and immediately clear to the skilled person because of his/her professional knowledge in view of the above description.

Therefore, innumerable changes, variations, modifications, alterations may be made and/or integrations in terms of materials and method used may be devised to configure, manufacture and assemble various constituents, components, subassemblies and assemblies according to their size, shapes, orientations and interrelationships.

While considerable emphasis has been placed on the specific features of the preferred embodiment described here, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiments without departing from the principles of the invention.

These and other changes in the preferred embodiment of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

The exemplary embodiments were selected and described in order to be able to best represent the principles and their possible practical application underlying the invention. Thereby, the skilled persons can optimally modify and use the invention and its different exemplary embodiments with reference to the intended use. ,CLAIMS:WE CLAIM:

1. A device for automatically detecting and indicating belt slackness in belt-drives of automotive engines, the device comprises:

• an ignition switch,

• alternator providing input signal of the frequency thereof,

• a crank/cam sensor for sensing the engine speed in revolutions per minute (rpm),

• a cluster controller (ECU) to convert the alternator frequency into engine speed in rpm and to calculate the actual engine speed available at the alternator,

• a comparator to compare actual engine speed calculated by the cluster controller with the engine speed sensed by the crank/cam sensor, and

• warning means to alert the automobile user for taking corrective action, if the actual engine speed available at the alternator is less than the engine speed sensed by the crank/cam sensor.

2. Device as claimed in claim 1, wherein the comparator signals belt tension to be correct, when the actual engine speed available at the alternator as calculated by the cluster controller is equal to the engine speed sensed by the crank/cam sensor.

3. Device as claimed in claim 1, wherein the comparator signals belt tension to be incorrect, when the actual engine speed available at the alternator as calculated by the cluster controller is less than the engine speed sensed by the crank/cam sensor by a predetermined value, the device initially alerts the vehicle driver that the belt-tension is not correct and remedial action should be taken.

4. Device as claimed in claim 3, wherein the device sends signal to the cluster controller, if the actual engine speed available at the alternator as calculated by the cluster controller is more than the engine speed sensed by the crank/cam sensor by a value exceeding the predetermined value.

5. Device as claimed in claim 3, wherein the device alerts the vehicle driver by means of a visual display.

6. Device as claimed in claim 3, wherein the device alerts the vehicle driver by means of an audible alarm.

7. Device as claimed in claim 3, wherein the device alerts the vehicle driver by means of a tell-tale indicator.

8. Device as claimed in claim 3, wherein the device alerts the vehicle owner and the service station or the vehicle user to change the alternator pulley belt, if the actual engine speed available at the alternator as calculated by the cluster controller is less than the engine speed sensed by the crank/cam sensor by a value exceeding the predetermined value.

9. Device as claimed in claim 8, wherein the device alerts the vehicle owner and the service station or the vehicle user by sending an SMS on the predefined mobile number of the vehicle owner and the service station or the vehicle user.

10. A method for automatically detecting and indicating belt slackness in belt-drives of automotive engines, the method comprises the following steps:

• Supplying signal to the cluster controller (ECU) on switching on the vehicle ignition switch,

• Obtaining frequency input signal from the alternator and forwarding the same to the cluster controller (ECU),

• Obtaining rotational speed (rpm) of the engine by means of the crank/cam speed and forwarding to the same cluster controller (ECU),
• Converting the alternator frequency into the engine speed in rpm and calculating the engine speed actually available at the alternator by means of the cluster controller (ECU) and forwarding the same to the comparator,

• Comparing the engine speed actually available at the alternator as calculated in the cluster controller with the engine speed sensed by the crank/cam sensor,

• Signaling to the vehicle driver the belt tension to be correct, if the actual engine speed available at the alternator as calculated by the cluster controller is equal to the engine speed sensed by the crank/cam sensor,

• Alerting the vehicle driver by means of a visual display and/or audible alarm and/or a tell-tale indicator, if the actual engine speed available at the alternator calculated by the cluster controller is less by a predetermined value than the engine speed sensed by the crank/cam sensor, indicating to the vehicle driver that the belt-tension is not correct and remedial action should be taken, or sending a signal to the cluster controller, if the actual engine speed available at the alternator as calculated by the cluster controller is more than the engine speed sensed by the crank/cam sensor by a value exceeding the predetermined value, or

• Alerting the vehicle owner and the service station or the vehicle user by sending an SMS on the predefined mobile number to change the alternator pulley belt, if the actual engine speed available at the alternator as calculated by the cluster controller is less than the engine speed sensed by the crank/cam sensor by a value exceeding the predetermined value.

Dated: this day of 31st July, SANJAY KESHARWANI
APPLICANT’S PATENT AGENT