THE PATENTS ACT, 1970

(39 of 1970) & The Patents Rules 2003

COMPLETE SPECIFICATION

(SECTION 10 and Rule 13)

1. Title of the Invention:

AN APPARATUS AND METHOD TO DETERMINE TIRE PRESSURE ABNORMALITY IN A VEHICLE

2. Applicants: a. Name: Bosch Limited

Nationality: INDIA

Address: Post Box No 3000, Hosur Road, Adugodi, Bangalore

- 560030, Karnataka, India b. Name: Robert Bosch GmbH

Nationality: GERMANY

Address: Stuttgart, Feuerbach, Germany

Complete Specification:

The following specification describes and ascertains the nature of this invention and the manner in which it is to be performed: Field of the invention:

[0001] The present invention relates to an apparatus and method to determine tire pressure abnormality in a vehicle.

Background of the invention:

[0002] An optimum tire pressure level is important for ride performance, vehicle condition and most importantly, rider safety. Thus, a system which can estimate tire pressure (at least sub-critical conditions) at a very low cost and inform the rider of the same creates tangible value. Further there is a constraint of not knowing the true speed of the vehicle (unless vehicle has an accurate GPS) as vehicle speed as measured by onboard sensors is derived from tire angular speeds, which are itself compromised in the case of deflation.

[0003] A patent literature US2002194904 discloses apparatus and method for detecting decrease in air-pressure for use in two-wheeled vehicle, and program for judging decompression for use in two-wheeled vehicle. An apparatus for detecting decrease in air-pressure for use in a two-wheeled vehicle including: a wheel speed detecting means for detecting wheel speeds; an acceleration calculating means for obtaining accelerations of a vehicle body of the two-wheeled vehicle; a slip rate calculating means for calculating slip rates when the acceleration of the vehicle body is in a specified range which is proximate to zero; an average value calculating means for obtaining average values of the slip rates and average vehicle body speeds; a difference calculating means for obtaining differences between the average values of the slip rates and a reference value which is based on an average vehicle body speed as preliminarily set when an internal pressure is normal; and a means forjudging decrease in internal pressure. A decrease in air-pressure in a twowheeled vehicle can be judged so as to enable safe driving.

Brief description of the accompanying drawings:

[0004] An embodiment of the disclosure is described with reference to the following accompanying drawing, [0005] Fig. 1 illustrates a block diagram of an apparatus to determine tire pressure abnormality in a vehicle, according to an embodiment of the present invention, and [0006] Fig. 2 illustrates a method determining tire pressure abnormality in a vehicle, according to the present invention.

Detailed description of the embodiments:

[0007] Fig. 1 illustrates a block diagram of an apparatus to determine tire pressure abnormality in a vehicle, according to an embodiment of the present invention. The apparatus 120 comprises at least one controller configured to, receive and measure wheel speeds of a front wheel and a rear wheel using respective wheel speed sensors 102, 104, as input signals while the vehicle 100 is in motion. The controller computes rate of change of vehicle speed using at least one of the wheel speed sensors 102, 104 or by estimating the vehicle speed using engine speed and the gear ratio or using an accelerometer, and detects a stable operating zone. The stable operating zone refers to acceleration nearly or proximate to zero or within range with upper and lower values, characterized in that, the controller calculates relative wheel speed difference followed by cumulatively averaging the relative wheel speed difference while the vehicle 100 is detected in the stable operating zone, for a threshold time duration and raster. The threshold time duration ensures that false positives are avoided. The relative wheel speed difference is calculated using the wheel speeds of the front wheel and the rear wheel. The controller further calculates a difference between the cumulative average value and a reference value, followed by calculation of an abnormality parameter. The abnormality parameter is defined as average of differences. The controller determines the tire pressure abnormality in any one of the front wheel and the rear wheel based on comparison of the abnormality parameter with a predetermined range limits.

[0008] In accordance to an embodiment of the present invention, the controller is also configured to dynamically calibrate the reference value for the vehicle 100 after every completion of an air refill event. The air refill event signifies that the air in both the tires of the vehicle 100 are filled to standard levels as per the type of concerned vehicle 100. The air refill event is indicated manually or detected automatically.

[0009] In accordance to an embodiment of the present invention, the apparatus 120 is at least one selected from a group comprising an internal device comprising an Electronic Control Unit (ECU) 110 of the vehicle 100, and an external device comprising a cloud based device 108 and a communication device 112 and a combination thereof. The internal device denotes that the device is internal or part of the vehicle 100. Similarly, the external device denotes that the device is externally interfaced with the vehicle 100 and is generally not part of the vehicle 100. The ECU 110 (or controller) is at least one of an Engine Management System (EMS) controller, a Tire Pressure Monitoring System (TPMS) controller, a Telematics Control Unit (TCU) controller, Anti-lock Braking System (ABS) ECU, a Body Control Unit (BCU), a Human-Machine Interface (HMI) cluster unit, other vehicular controllers and a combination thereof. The communication device 112 corresponds to electronic computing devices such as smartphone, wearable electronics such as smart watch, intelligent HMI cluster (or connected cluster) in the vehicle etc. The cloud based device 108 corresponds to cloud computing architecture having network of servers, databases connected with each other and vehicle 100 for processing of inputs and providing outputs.

[0010] According to an embodiment of the present invention, the apparatus 120 is usable/implementable in different manners or scenarios. In a first scenario, the apparatus 120 is just the ECU 110 of the vehicle 100. Thus, the tire pressure abnormality is determined and then indicated to the driver directly by the ECU 110 of the vehicle 100. In a second scenario, the apparatus 120 is the external device, i.e. at least one of the cloud based device 108 and the communication device 112 of the driver who drives the vehicle 100. In a third scenario, the apparatus 120 is combination of the internal device and external device, i.e. the apparatus 120 is combination of the ECU 110 and the cloud based device 108, or combination of the ECU 110 and the communication device 112 or combination of the cloud based device 108 and the communication device 112 or the combination of the ECU 110, the cloud based device 108 and the communication device 112. The second scenario and the third scenario are explained later.

[0011] The apparatus 120 which is at least one internal device and the external, refers to computing devices/units comprising components such as memory element 106 such as Random Access Memory (RAM) and/or Read Only Memory (ROM), Analog-to-Digital Converter (ADC), Digital-to- Analog Convertor (DAC), clocks, timers and a processor (such as Central Processing Unit (CPU)) (capable of implementing machine learning) connected with the each other and to other components through communication bus channels. The components mentioned are just for understanding and may have more or less components as per requirement. The memory element 106 of the apparatus 120 is prestored with logics or instructions or programs or applications or thresholds or values which is accessed by the processor as per the defined routines. The internal components of the controller are not explained for being state of the art, and the same must not be understood in a limiting manner. The apparatus 120 is capable to communicate through wired and wireless means such as but not limited to Global System for Mobile Communications (GSM), 3G, 4G, 5G, Wi-Fi, Bluetooth, Ethernet, serial networks, Universal Serial Bus (USB) cable, micro-USB, and the like.

[0012] In accordance to an embodiment of the present invention, the apparatus 120 is configured and provided to dynamically calibrate the reference value. The controller configured to receive an input indicating completion of the air refill event, receive and measure wheel speeds of the front wheel and the rear wheel using respective wheel speed sensors 102, 104 while the vehicle 100 is in motion, compute rate of change of the vehicle speed using at least one of the wheel speed sensors 102, 104 or using an estimated vehicle speed or using the accelerometer, and detect the stable operating zone. The controller then calculates the relative wheel speed difference followed by the cumulative average value of the relative wheel speed difference while and whenever the vehicle 100 is detected in the stable operating zone. The relative wheel speed difference is calculated using the wheel speeds of the front wheel and the rear wheel. The calculated cumulative average value as then set as the reference value for future evaluations. When the air-refill event is detected again, the reference value is recalculated or recalibrated. The process of calibration is needed to ensure that the abnormality parameter is unique for the vehicle 100 and varies as the vehicle 100 or the tires deteriorates or ages.

[0013] In accordance to an embodiment of the present invention and as per the second scenario, the apparatus 120 is the external device, i.e. any one of the cloud based device 108 and the communication device 112. For ease of understanding, the apparatus 120 is now explained as the cloud based device 108, but the same explanation is applicable when the external device is the communication device 112. When the apparatus 120 is the cloud based device 108, the cloud based device 108 receives all the tire pressure monitoring related signals (input signals) directly from the ECU 110. The ECU 110 does not process the input signals and directly transmits the input signal to the cloud based device 108 through the TCU or through the communication device 112. The cloud based device 108 is configured to receive the input signals from the ECU 110 comprising wheel speeds for the front wheel and the rear wheel, identify all time instances at which the stable operating zone of the vehicle 100 is present, extract input signals of wheel speeds of only those which fall under the stable operating zone. The input signals are received until at least a minimum required datasets are met. The datasets refer to those set of input signals which contains the wheel speed for each wheel at those instances when the stable operating zone is detected.

[0014] The cloud based device 108 then calculates the differences by comparing the average values with the dynamically calibrated reference value and calculates the abnormality parameter. The tire pressure abnormality is determined based on comparison of the abnormality parameter with the predetermined range limits. If the abnormality parameter is greater than the upper limit value, then air pressure in the rear wheel is depreciated. If the abnormality parameter is lesser than the lower limit value, the air pressure in the front tire is depreciated. The cloud based device 108 then transmits the results back to the ECU 110 of the vehicle 100, where the tire pressure abnormality is indicated to the driver through any output means 114 such as audio, visual (such as blinking pattern or colors), display (such as instrument cluster), haptic and combination thereof.

[0015] Similarly, when the apparatus 120 is the communication device 112, the communication device 112 is connected to the ECU 110 through suitable communication or networking means as described before, such as but not limited to Bluetooth™, Wi-Fi, cables, etc. The application installed in the communication device 112 process the input signals received from the ECU 110 and sends back the result for display to the driver. Also, the application stores the result internally for display to the driver for later reference. The data transmission between cloud computing device 108 and the communication device 112 is also possible.

[0016] In accordance to an embodiment of the present invention and as per the third scenario, the apparatus 120 is combination of internal device (the ECU 110) and the external device. The processing of the input signals is shared among the internal device(s) and the external device(s) and the result is finally displayed on the vehicle 100 (such as on the dashboard, or the instrument cluster) on in the communication device 112. When the apparatus 120 is the external device, the external device receives the input signals from the ECU 110 comprising wheel speeds for the front wheel and the rear wheel which comes under the stable operating zone. The inputs signals are received for at least a minimum required datasets are met, such as 1500 datasets (less or more can be used based on specific requirements) of the wheel speeds for each of the front wheel at the same time instant which denotes the stable operating zone. Further, the stable operating zone may be distributed during the drive of the vehicle 100 and need not be continuous. For example, consider the apparatus 120 as combination of the ECU 110 and the cloud based device 108. The ECU 110 pre-processes the input signals (wheel speed signals) and identifies the time instances at which the stable operating zone is present, and sends only necessary inputs signals (datasets) to the cloud based device 108. In an alternate embodiment, instead of wheel speeds, only wheel speed differences are sent to the cloud based device 108. Now, the cloud based device 108 processes on reduced and essential number of input signals thus providing faster results back to the vehicle 100. The apparatus 120 indicates the tire pressure abnormality at any one of during a driving of the vehicle 100 and after end of the driving.

[0017] In accordance to an embodiment of the present invention, the air refill event is manually set through any one selected from a group comprising an application installed in the communication device 112, and a button in the vehicle 100 When the communication device 112 is connected to the ECU 110, then a calibration process is started by pressing a touch based button in the application installed in the communication device 112. Alternatively, the button provided in the vehicle 100 is used to trigger the calibration process. In another alternative, an existing button in the vehicle 100 is used for the calibration process. In yet another embodiment, the air refill event is automatically detected, and the calibration is automatically triggered. Further, the vehicle 100 is any one selected from a group comprising a two- wheeler such as scooter, motorcycle, a three-wheeler such as autorickshaw, a four wheeler such as cars, and multi-wheel vehicles 100.

[0018] In accordance to an embodiment of the present invention, there are different manners in which the stable operating zone is determined. In an embodiment, at least one of the wheel speed sensors 102, 104 is directly used to determine the vehicle speed and thereafter the operating zone. In another embodiment, the vehicle speed is estimated from engine speed (using an engine speed sensor) and current gear position and optionally radius of the wheel. In yet another embodiment, an existing accelerometer of the vehicle or an Inertial Measurement Unit (IMU) or accelerometer of the communication device 112 docked in the vehicle is usable. The communication device 112 must be in communication with the ECU of the vehicle. [0019] Fig. 2 illustrates a method determining tire pressure abnormality in a vehicle, according to the present invention. The method comprises the plurality of steps, of which a step 202 comprises receiving and measuring wheel speeds of the front wheel and the rear wheel of the vehicle 100 using respective wheel speed sensors 102, 104 as input signals while the vehicle 100 is in motion. A step 204 comprises computing rate of change of vehicle speed using at least one of the wheel speed sensors 102, 104 or engine speed and gear ratio or accelerometer, and detecting the stable operating zone. The method is characterized by a step 206 which comprises, calculating the relative wheel speed differences followed by the cumulative average value of the relative wheel speed differences while and whenever the vehicle 100 is detected to be in the stable operating zone. The relative wheel speed difference is calculated using the wheel speeds of the front wheel and the rear wheel. A step 208 comprises calculating the difference between the cumulative average value and the reference value, followed by calculating the abnormality parameter. The abnormality parameter is the average of the differences. A step 210 comprises determining the tire pressure abnormality in any one of the front wheel and the rear wheel by comparing the abnormality parameter with a predetermined range limits. A step 212 comprises dynamically calibrating the reference value for the vehicle 100 after completion of every air refill event.

[0020] In accordance to the present invention, a method for dynamically calibrating the reference value is provided. The method comprises plurality of steps, of which a step 214 comprises receiving the input indicating completion of air refill event. The input is manually provided through the application installed in the communication device 112 which is in communication with the vehicle 100 or a dedicated button in the vehicle 100. A step 216 comprises receiving and measuring wheel speeds of the front wheel and the rear wheel using respective wheel speed sensors 102, 104 as input signals while the vehicle 100 is in motion. A step 218 comprises calculating rate of change of vehicle speed using at least one of the wheel speed sensor 102, 104 and detecting the stable operating zone. A step 220 comprises calculating the relative wheel speed differences followed by the cumulative average value of the same while the vehicle 100 is detected in the stable operating zone. The relative wheel speed difference is calculated using the wheel speeds of the front wheel and the rear wheel. A step 222 comprises setting the average value as the reference value. The reference value is calculated whenever the input indicating the completion of the air refill event is received. Alternatively, a request is received from the driver whenever there is a need for the calibration. The method comprises indicating the tire pressure abnormality at any one instance comprising during the driving of the vehicle 100 and after end of the driving. There is no general or common reference value for all the vehicles 100 and all the drivers. The dynamic calibration of the reference value is unique to respective vehicle 100 and corresponding driver.

[0021] The method is executed by at least one apparatus 120 selected from a group comprising the internal device such as an Electronic Control Unit (ECU) 110 of the vehicle 100, and the external device comprising at least one of the cloud based device 108 and the communication device 112. A portable computing device is equally usable in place of the communication device 112. The ECU 110 is at least one of the Engine Management System (EMS) controller, the Tire Pressure Monitoring System (TPMS) controller, the Telematics Control Unit (TCU) controller, the Anti-lock Braking System (ABS) ECU, the Body Control Unit (BCU), the Human-Machine Interface (HMI) cluster unit, other vehicular controllers, and the combination thereof. Further, the air refill event is performed manually through any one selected from a group comprising the application installed in the communication device 112, where the communication device 112 is in communication with the ECU 110, and/or the button in the vehicle 100. Alternatively, the air refill event is detected automatically.

[0022] In accordance to an embodiment of the present invention, an Indirect Tire Pressure Monitoring Systems (TPMS) for two-wheelers with wheel speed data using radial tire dynamics is provided. The reference value is dynamically calibratable as per the type of vehicle 100 and the driver, and does not uses a common values for different vehicles 100 or different vehicles 100 of the same type. The present invention aims to provide a low-fidelity estimation of tire pressure abnormality based on stable operating zone of the vehicle 100. The present invention provides a safety /maintenance feature which estimates tire pressure level in each tire of the vehicle 100 (such as the motorcycle) without using additional sensors. Further, the present invention uses relative wheel speed difference rather than slip ratio or slip rate.

[0023] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.