Abstract: An apparatus for alarming of tire deflation is provided in which reliability of an alarm is raised by a manner of alarming slightly when tire deflation is small and detection accuracy of a deflation detection mechanism is small, while alarming largely when tire deflation is large and deflation is detected with large accuracy. The apparatus comprises deflation detection means for detecting tire deflation; vehicle speed detection means for detecting a speed of a vehicle; and alarm means for deciding an alarm level depending on a detected tire deflation and a detected vehicle speed, and providing an alarm at the decided alarm level.

Abstract: A method and system for monitoring and measuring the amount of deflection of a pneumatic tire wherein said monitoring system in the tire detects tire sidewall deflection by measuring the length of the tire contact patch area relative to the total circumference of the tire. The embedded sensor device generates a signal which varies as it passes through the tire contact patch within the tire on a moving vehicle. If the vehicle is moving at a constant speed, the ratio of time which the sensor spends inside the contact patch to the time the sensor spends outside the contact patch is proportional to tire deflection. Sensor electrical signals are digitized and counted to determine deflection, tire speed and the number of tire revolutions to improve performance of both the tire and the vehicle.

Abstract: A reduction in pressure in tires fitted to follower wheels and driven wheels is precisely determined irrespective of slipping states of the driven wheels. A driven wheel slip rate calculating means M1 calculates driven wheel slip rates .lambda.L and .lambda.R. A driven wheel torque calculating means M2 calculates a driven wheel torque TQDW. A driven wheel slip rate estimating means M4 estimates a characteristic of variation in driven wheel slip rates .lambda.L and .lambda.R relative to the variation in driven wheel torque TQDW using a least squares method. A rotation-number ratio calculating means M5 calculates ratios CVWL and CVWR of the numbers of rotations of the follower wheels to the numbers of rotations of the driven wheels in a state in which the driven wheel torque in a graph of the variation characteristic is equal to zero.

Abstract: A method of determining the inflation pressure of one or more pneumatic tires on a moving vehicle having a plurality of n wheels fitted with tires by performing a set-up procedure comprising, for a range of tire inflation set-up procedure comprising, for a range of tire inflation pressures including all the vehicle tires at their scheduled inflation pressure and combinations of one or more tires at a range of pressures below their scheduled and for a range of vehicle speeds and driving conditions such as accelerating, braking, straight-ahead driving and cornering, deriving for each of the wheels a speed value Cn proportion to the wheel angular velocity, determining and saving the relationship of the set of set-up speed values to each related tire pressure, and subsequently in normal driving monitoring at intervals of time the wheel speed signals of the wheels on the vehicle, deriving an equivalent set of normal driving speed values based on these monitored wheel speed signals, obtaining the associated tire in

Abstract: An automatic initialization method including the steps of: measuring and monitoring acceleration of a vehicle in a lateral direction, defining correction values for each tire of the vehicle, and obtaining baseline values under normal pneumatic pressure conditions by using only data of angular velocity of rotation of each tire when the acceleration of the vehicle in the lateral direction ranges from -0.03 g to +0.03 g, when the steering angle of the vehicle ranges from -15.degree. to +15.degree., or when both the lateral acceleration and the steering angle are in the specified ranges. In the method of the present invention, only the data of angular velocities of tires is automatically picked up in the optimum driving status and initialization can be performed with high precision.

Abstract: A system and method that monitors four wheel sensors of an automotive vehicle to determined changes in the effective rolling radii of any wheel and a low pressure tire condition. Certain vehicle operating conditions, such as excessive or very low speeds, braking, and turns, are determined from the sensor outputs and are used to prevent erroneous detection of changes in effective rolling radii. Data from the sensors that is determined to be acceptable is accumulated over time as displacement values for each wheel. When the displacement values exceed a predetermined value, a metric function is used to compare differences detected in accumulated displacement values for the front pair of wheels and for the rear pair of wheels. If the difference between compared pairs of wheels is excessive, as compared with a predetermined baseline metric value, a low tire condition is detected.

Abstract: An evaluation circuit forms quotients based on the detected wheel speeds and compares the quotients to each other. Depending on the results of the comparison, a signal which represents the condition of the tires is generated, which signal activates a display for the benefit of the driver. In a preferred embodiment, the rate of change of the quotients over time is also determined to provide a basis for signal generation.

Abstract: In accordance with a tire air-pressure reduction detecting apparatus of the present invention, if it is judged that the tires all have a normal air pressure, it is judged whether or not a count value (C) is not less than a steady-state count (L.sub.2), and then if the count value (C) is not less than the steady-state count (L.sub.2), a counter (CNT) is decremented. That is, the count value (C) is kept to the steady-state count (L.sub.2) at the lowest, from which incrementation is started. On the other hand, if it is judged that a tire air pressure is reduced, it is judged whether or not the count value(C) is less than an upper counting limit (L.sub.1), and then if the count value (C) is less than the upper counting limit (L.sub.1), the counter (CNT) is incremented. That is, the count value (C) is kept to the upper counting limit (L.sub.1) at the highest, from which decrementation is started. Then, if the count value (C) is not less than a warning threshold count (N.sub.

Abstract: A technique to indicate a different-diameter wheel such as a temporary tire and to accurately correct the wheel speed of the different-diameter wheel is determined. Wheel speeds of a pair of left and right driven wheels are detected by wheel speed sensors and wheel speeds of a pair of left and right follower wheels are detected by wheel speed sensors. Yaw rates are calculated from the wheel speeds of the left and right wheels, and yaw rates are calculated from the wheel speeds of the wheels located diagonally. Which wheel of the four wheels is a different-diameter wheel is determined based on the magnitudes of the four yaw rates and the wheel speed of the different-diameter wheel is corrected based on a ratio in wheel speed between the different-diameter wheel and the other wheels.

Abstract: A pressure sensing system is formed by a sensor mounted one to rotate with each tire and adapted to sense the pressure in the tire and generate a signal corresponding to the tire pressure, a movable contact system is moved into an operative position only when the vehicle is stopped and provides power (if required) to the sensor and contacts to deliver the electrical signals indicative of the tire air pressure to the vehicle body where it may be displayed for the operator's convenience.

Abstract: A system for use with an automotive vehicle supported on front and rear pairs of road wheels to detect a drop in a tire air pressure for each of the road wheels. When the vehicle is detected as operating substantially in a steady straight line driving condition, the road wheel having a dropped tire air pressure is specified based on the angular speeds of rotation of the respective road wheels. This detection is made based on the angular road wheel speeds in view of changes in loads exerted in the respective road wheels caused by the tire air pressure drop.

Abstract: Rotational speed of a vehicle speed detecting gear 1 is detected by a detection element 2 using an MRE or the like and the detected signal is waveform-shaped by a waveform shaping circuit 3 to serve as a vehicle-speed pulse signal. The cycle of the vehicle-speed pulse signal is detected by a sampling circuit 4. The detected cycle of the pulse signal is multiplied by a predetermined multiplier in a multiplication circuit 6 and the multiplication result is divided by a predetermined divisor in a diving and pulsing circuit 8. Then, a pulse signal having the cycle equivalent to the division result is output as a divided vehicle-speed pulse signal.

Abstract: A method of and a device for detecting a pneumatic pressure drop of tires provided for a vehicle are disclosed. Rotational angular velocities of tires are determined and a judged value D is determined based on the determined rotational angular velocities. A speed of the vehicle, a front/rear acceleration FRA of the vehicle, a lateral acceleration LA of the vehicle and a turning radius R of the vehicle are substituted into a predetermined polynominal expression which is defined so that an influence of the turning radius R is exerted on all terms to determine a correction value. A judged value D' after correction is determined by correcting the judged value D using the correction value. It is judged whether a tire pressure drops or not, based on the judged value D' after correction. In such way, a tire pressure drop can be detected, accurately, excluding an influence of the turning radius R of the vehicle.

Abstract: A process for monitoring tire pressure by comparing and evaluating the rotating speeds of the individual wheels of the vehicle which is based on the formation of speed correction factors. The values of the individual correction factors, correlations between the correction factors for typical travel situations, and tolerances for the correction factors, which depend on the actual travel situation, are determined during a learning phase (i.e. phase 1). The deviations of the correction factors from the learned values are determined and evaluated during a subsequent identification phase (i.e. phase 2), taking into account the travel situation-dependent tolerances and the progression of the learning process.

Abstract: A tire pressure drop alarm device for judging a pneumatic pressure drop by calculating rotational angular velocities of tires provided for a four-wheel vehicle. When the vehicle is traveling on a road which varies in condition between left and right sides, a front/rear ratio of rotational angular velocities of the tires at the shoulder side of the road changes more markedly than that of rotational angular velocities of the tires at the center side, and a large time differential value appears. Therefore, it is possible to judge the traveling condition of the vehicle when the road condition varies between left and right sides. When it is judged that the traveling condition of the vehicle encounters a road condition which varies between left and right sides, the tire rotation of the four wheels is likely to become unbalanced, giving a false alarm even if the tire pressure does not drop. In this case, the judgment by the pneumatic pressure drop judging means is inhibited to prevent an issuance of a false alarm.

Abstract: The present invention is directed to a device for and a method of detecting a tire pressure drop for a four-wheel vehicle. When F1, F2, F3 and F4 are respectively taken as the rotational angular velocities of four tires, a judged value dF given by the following equation (A) is found:dF=(F1+F4)/(F2+F3) (A)The judged value dF is the ratio of the sum of the rotational angular velocities (F1+F4) of a pair of tires on a diagonal line to the sum of the rotational angular velocities (F2+F3) of the other pair of tires. If the pneumatic pressures of the four tires are all normal, (F1+F4)=(F2+F3), so that dF=1. On the other hand, if the pneumatic pressure of any one of the tires drops, dF.noteq.1. Accordingly, it is judged that the pneumatic pressure of a tire drops by comparing the judged value with a predetermined value.

Abstract: A method and device for detecting a deflated tire on a vehicle by comparing the rolling radii of the tires by means of comparing angular velocity speed signals from wheel speed sensors, one at each wheel, characterized by calculating an error value DEL', where ##EQU1## wherein C1, C2, C3 and C4 are angular velocity values for left-hand front, right=hand front, left-hand rear and right-hand rear wheels of the vehicle respectively, determining a correction factor LAT, calculating a corrected error value DEL whereDEL=DEL'-DELCORwhereinDELCOR=(LAT.times.A)+(B.times.LAT.sup.2)wherein A and B are vehicle related constants, and operating a tire warning indicator provided in the vehicle to indicate that at least one tire is deflated when it is sensed that the magnitude of the corrected error value DEL is in the range 0.05 to 0.5.

Abstract: The rotational speed difference between rotational speeds of front and rear road wheels of a motor vehicle is weighted by a first ratio, and the difference between the rotational speed difference between rotational speeds of front left and right road wheels and an average signal of reference steering angle or between the rotational speed difference between rotational speeds of rear left and right road wheels and the average signal of reference steering angle is weighted by a second ratio. A sum signal representative of the sum of the rotational speed difference weighted by the first ratio and the difference weighted by the second ratio is used to determine a pneumatic tire pressure reduction highly accurately even when running conditions of the motor vehicle change such as when the motor vehicle makes a turn.

Abstract: Method for tire pressure warning in a motor vehicle in which, instead of direct pressure measurement, the tire pressure is monitored indirectly by recording the dynamic rolling circumference of the tire and, in this way, to dispense with sensors, in particular if wheel speed sensors have already been installed in the vehicle.The method works on the basis of a wheel speed balance, within which speed scaling factors are determined. By comparing these scaling factors in pairs, determining the maximum deviation and checking whether a particular threshold value has been exceeded, a reliable tire pressure warning can be implemented with little outlay, in particular in the case of a wheel speed balance for each axle.

Abstract: According to the tire air-pressure reduction detecting apparatus and method of the present invention, when a vehicle travels, the detected rotational angular speeds F.sub.i of the tires W.sub.i are multiplied by correction coefficients C.sub.i to correct initial differences. Vehicle speed V.sub.0 is calculated based on angular speeds F.sub.i0, and is put in a relationship formula f(V) to obtain a front/rear wheel ration f(V.sub.0) corresponding to the speed V.sub.0. Based on the front/rear wheel ratio f(V.sub.1) corresponding to a speed V.sub.1 at which the correction coefficients C.sub.i have been obtained, and the ration f(V.sub.0), there is obtained a variation of the front/rear wheel ratio f(V.sub.0)/f(V.sub.1), by which rotational angular speeds F.sub.3, F.sub.4 are then multiplied. The products are used for detecting a reduction in the air pressure of a tire W.sub.i, thereby to calculate a judgement value D. When D satisfies the conditions:D<-D.sub.TH1 or D>D.sub.

Abstract: A system, method and apparatus for use on vehicles having road wheels with pneumatic tires that includes sensors that produce signals that are a measure of the rotational speed of said wheels, indicators arranged to provide information to the driver of the vehicle, and a computer operably associated with said sensors and indicators. The computer is arranged to monitor the wheel speed sensors during vehicle operation, and to perform at least one of the functions of: determining a value that represents tire inflation pressure and signaling the driver when this value falls below a predetermined value, determining a value that represents tire inflation pressure and signaling this value to the driver, calculating a value that represents vehicle speed and signaling this value to the driver, and calculating a value that represents distance traveled by the vehicle and signaling this distance to the driver.

Abstract: A method for detecting bad stretches of road includes ascertaining a tripping variable representing acceleration of at least one wheel of a vehicle. A bad stretch of road is detected if the amount of the tripping variable exceeds a predeterminable limit value. The tripping variable is dependent on at least two segment times that the wheel needs to pass through associated angle segments.

Abstract: In a method for determining pressure loss in a pneumatic vehicle tire on a driven axle of a vehicle the rotational velocities of the wheels are measured and slip values for the driven wheels are calculated therefrom. Simultaneously, wheel drive forces of the vehicle for the calculated slip values are determined. The wheel drive forces and the corresponding calculated slip values are correlated and a characteristic curve is produced. The characteristic curve is compared to a predetermined characteristic curve range and a warning signal is generated when the characteristic curve is outside the predetermined characteristic range. The device for performing the method has sensors for measuring the rotational velocities of the wheels. A device for determining slip of the driven wheels from the measured rotational velocity is provided. A device for determining the wheel driven forces is present.

Abstract: An absolute vehicle speed determining system is provided. This system includes generally a first sensor for detecting an unsprung vibration frequency component acting on a front wheel and a second sensor for detecting an unsprung vibration frequency component acting on a rear wheel. A phase difference between the unsprung vibration frequency components is found to project an absolute speed of a vehicle based on the phase difference and a wheel base of the vehicle. In addition, a tire condition monitoring system is provided which is designed to monitor properties of the tire, for example, the inflation pressure, the type of tire, or the amount of tire wear using the absolute speed of the vehicle projected.

Abstract: A method of detecting a deflated tire on a vehicle by comparing the rolling radii of the tires by comparing angular velocity speed signals C1, C2, C3, and C4 from wheel speed sensors, one at each wheel, comprising the steps of: calculating in normal driving an error value DEL'; determining a correction factor LAT, by calculating from the four angular velocity values respective first, second, third and fourth deciding factors MC1, MC2, MC3, MC4; summing the four deciding factors and multiplying this sum by a centralizing constant (K) to give a central deciding factor MPSD and selecting the correction factor LAT according to pre-determined rules; determining vehicle related constants A, B, C for clockwise cornering and E, F, G for anti-clockwise cornering; calculating a corrected error value DEL; and operating a tire warning indicator to indicate that at least one tire is deflated when the magnitude of the corrected error value DEL is sensed in the range 0.05 to 0.5.

Abstract: A method of detecting a deflated tire on a vehicle by comparing the rolling radii of the tires by comparing angular velocity speed signals C1, C2, C3, and C4 from wheel speed sensors, one on each wheel, comprising the steps of: calculating in normal driving an error value DEL' by processing the four angular velocity speed signals C1-C4 and expressing the result as a percentage of the mean of the sums, DEL'=(C1+C4-C2-C3).times.50/((C1+C2+C3+C4)/4); sensing when the magnitude of the error value DEL' is in the range 0.05 to 0.5 and when it is carrying out the step of deciding which tire is apparently deflated by comparison of the angular velocity speed signals C1-C4 with each other, calculating a wheel error value DEL'FAC(W) for each wheel W produced with the deflated tire by the method for DEL' in normal driving, where DEL'FAC=(C1+C4-C2-C3).times.

Abstract: A hydroplaning detection system comprising AM specific frequency component extraction AM, which comprises a band-pass filter for extracting signal components PS in a main frequency band corresponding to the wheel rotation speed or the vehicle speed from wheel rotation speed signals, and a band-pass filters for respectively extracting signal components PL in other frequency bands, and AM determining the occurrence of hydroplaning based on the ratio PL/PS between the signal components PS in the main frequency band and the signal components PL in other frequency bands.

Abstract: A method for detecting a deflated condition of a tire, comprises the steps of: detecting the angular velocity of each wheel, producing a signal proportional to the angular velocity detected, directly detecting the pneumatic pressure of a tire for only one wheel, producing a signal proportional to the pneumatic pressure detected, and arithmetically processing the signals produced in the preceding steps. A device to which this method is applied is also disclosed.

Abstract: A subtractor calculates an actual wheel speed difference between rotational speeds of left and right wheels on a motor vehicle, and a steering angle converter calculates an actual steering angle from the actual wheel speed difference. The difference between the actual steering angle and an adequate steering angle which is produced based on a lateral acceleration is compared with a predetermined reference range. If the difference between the actual and adequate steering angles exceeds the predetermined reference range, then the pneumatic pressure of a tire on one of the left and right wheels is determined as being lowered. In the steering angle converter, a weight value is established according to a running condition of the motor vehicle, and the calculated actual steering angle or comparative sensitivity is varied according to the weight value.

Abstract: A method for detecting a deflated condition of a tire, comprises the steps of: detecting the angular velocity of each wheel, producing a signal proportional to the angular velocity detected, directly detecting the pneumatic pressure of a tire for only one wheel, producing a signal proportional to the pneumatic pressure detected, and arithmetically processing the signals produced in the preceding steps. A device to which this method is applied is also disclosed.

Abstract: A tire inflation pressure monitoring apparatus comprises a reference magnet fixed to a wheel, a movable magnet whose position shifts depending on the inflation pressure of a tire, and a magnetic sensor for detecting the magnetism of the magnets. The reference magnet can be moved in the axial direction of the wheel by means of a position adjusting mechanism. Thus, a relative distance from the reference magnet to the movable magnet can be adjusted to a fixed value (e.g., zero) at the time of calibration. An electric circuit section is stored with a computation formula or a map indicative of the relationships between outputs of the magnetic sensor and minimum distances from the magnets to the magnetic sensor. In detecting the inflation pressure of the tire, data associated with the minimum distances from the magnetic sensor to the magnets are obtained according to the computation formula or map on the basis of the outputs obtained by means of the magnetic sensor.

Abstract: Vehicle tires each contain a sender including a microprocessor, a radio transmitter, a pressure detector and a magnetic switch for sending a radio signals indicating sender ID, pressure data and change of switch state. An on-board receiver unit having a microprocessor evaluates the transmitted data and displays pressure condition information. A portable magnet is placed near each tire, in turn, to operate the magnetic switches, resulting in a sequential transmission of sender ID codes which allows the receiver unit to learn the tire position of each sender. An inertia switch in the tire triggers a radio transmission and the receiver unit considers the absence of a transmission when expected as a failure and displays a service needed message. A remote portable sender transmits signals for door unlocking or locking, trunk opening and interior light control. The receiver unit responds to the signals and issues commands to appropriate actuators.

Abstract: A method for detecting a deflated condition of a tire, comprises the steps of (a) detecting the angular velocity of each wheel, (b) producing a signal proportional to the angular velocity detected, (c) detecting acceleration of the vehicle in a forward or backward direction, (d) obtaining a speed of the vehicle in the forward or backward direction by integrating the detected acceleration, (e) producing a signal proportional to the obtained speed of the vehicle in the forward or backward direction, and (f) arithmetically processing the signals produced in steps (b) and (e). In step (f), the angular velocity of each wheel at the speed in the forward or backward direction obtained in step (d) is obtained from a normal wheel angular velocity table previously prepared; and the result is compared with the angular velocity detected in step (a), and if the difference therebetween is within the range of 0.05% to 0.60%, a device for warning of a deflated tire is operated.

Abstract: An indicator housing is arranged in operative communication to a plurality of sensor housings, each mounted to a backing plate of an associated vehicle, such that each sensor housing includes a sensor rod reciprocatingly and slidably projecting from the sensor housing, such that upon the respective tire relative to each sensor housing losing air pressure and bulging, deflection of the sensor rod is indicated within the vehicle through the indicator housing.

Abstract: A method and apparatus for detecting a partially deflated tire on a vehicle having four tires each mounted on a wheel. Each wheel being provided with a signal generator for producing a series of digital signals or pulses spaced apart by equal increments by angular rotation of the respective tire and wheel assembly characterized by calculating from one of the series of signals reflective of the vehicle speed. The method includes selecting an appropriate interval for deflation detection, measuring the speed of rotation for each of the four wheels, storing the speeds found, repeating the measuring step for at least three consecutive successive equal intervals, averaging the speeds to produce an average speed signal for each wheel, processing the four signals in a processing unit which subtracts the sum of the signals from one pair of diagonally opposite wheels from the sum of the signal from the other pair of diagonally opposite wheels, sensing when the magnitude of the result is between 0.05% and 0.

Abstract: A pneumatic tire pressure determining system on a motor vehicle detects an actual rotational speed difference between rotational speeds of front or rear left and right road wheels of the motor vehicle, detects an operating condition of the motor vehicle, and calculates an adequate rotational speed difference between rotational speeds of the front or rear left and right road wheels based on the detected operating condition of the motor vehicle. The system compares the adequate rotational speed difference and the actual rotational speed difference, and when the difference between the compared actual and adequate rotational speed differences exceeds a predetermined value, the system determines a pneumatic tire pressure reduction.

Abstract: A central tire inflation system for controlling the tire inflation pressure of a driven wheeled vehicle includes a compressed air source connected through a conduit system with the vehicle tires, a controllable valve system connected in the conduit system and a tire pressure controller connected with and controlling operation of the valve system to selectively increase or decrease inflation pressure includes wheel slip detectors and a vehicle speed detector for generating a signal proportional to detected slippage rate and vehicle speed, and signal processing system for utilizing the slippage signal and vehicle speed signals to control the valve system to automatically control tire inflation pressure in response to conditions encountered to minimize slippage and maintain tire inflation pressure at the highest pressure commensurate with safety and economic operation.

Abstract: A tire pressure and temperature monitoring system for measuring tire inflation pressure and anomalous temperature of rotating tires in a moving vehicle by means of optoelectronic devices located in the stationary structure of the vehicle and an elastic diaphragm that rotates with the wheel and tire. The combined use of optoelectronic components and elastic diaphragms, provides a marked improvement in performance, reliability and cost over previously disclosed magnetic or radio frequency pressure measurement systems. The optoelectronic detector elements are also used to identify those tires whose side wall temperature is significantly higher than the side wall temperature of the other tires. In addition, the system can also be used as a measurement of individual wheel rotational speed and related wheel motion.

Abstract: A tire pressure detecting portion includes a housing, provided within the tire, within which a piezoelectric element is provided so as to be deformed by the tire pressure. The capacitance of said piezoelectric element is changed in accordance with its deformation. The piezoelectric element is electrically connected with a first coil diposed within said tire. The first coil is electromagnetically coupled with an excitation coil and a receiving coil, both of which are provided in the vehicle. The excitation coil provides an excitation voltage whole frequency is changed within a predetermined range including a resonant frequency. When the received voltage has the resonant frequency, a correspondinq tire pressure is determined based on a data map showing the relationship between said resonant frequency and the tire pressure.

Abstract: A method of detecting a deflated tire on a vehicle by comparing the rolling radii of the tires by comparing angular velocity signals from wheel speed sensors at each wheel comprising the steps of calculating the factors ##EQU1## where C1, C2, C3 and C4 are the signals for the speeds of the front left-hand, front right-hand, rear left-hand and rear right-hand wheels of the vehicle, monitoring these factors and if the value of one or more factor becomes greater than 1.0005 or less than 0.9995, producing a warning signal to indicate that a tire has become partially or completely deflated.

Abstract: A method of detecting a deflated tire on a vehicle by comparing the rolling radii of the tires by comparing angular velocity speed signals from wheel speed sensors. One wheel speed sensor being provided at each wheel. Before the comparison of the signals is carried out, corrected wheel speed signals for each of the second, third and fourth wheels are calculated giving corrections for a set of factors comprising vehicle speed, lateral acceleration and longitudinal (fore/aft) acceleration. The corrections each comprise a constant for the factor concerned times the respective factor. The set of constants for each wheel is derived by taking the vehicle through a range of speeds, lateral and fore/aft accelerations and using multiple regression techniques and the respective factors are calculated from the set of uncorrected wheel speed signals so that comparison of the wheel speeds can be made without false signals from tire deflections caused by speed, lateral or fore/aft acceleration induced tire deflections.

Abstract: A method of detecting a partially deflated pneumatic tire on a vehicle having four tires each mounted on a wheel including the steps of sensing the angular velocity of each wheel and producing a signal proportional thereto, processing the four signals in a processing unit which subtracts the sum of the signals from one pair of diagonally opposite wheels from the sum of the signals from the other pair of diagonally opposite wheels, sensing when the magnitude of the result is between 0.05% and 0.6% of the mean of the two sums to produce a signal factor and when said signal factor is present operating a warning device to indicate a tire is partially or completely deflated wherein the angular velocity of each wheel is measured simultaneously by a pulse generator providing a digital signal of more than twenty pulses per revolution of the wheel and a second signal of a single pulse per revolution of the wheel and the two angular velocity signals are both used.

Abstract: The relative speed of the tires of a vehicle is monitored as an indication of the operating state of the vehicle, wherein if the vehicle is not operating in one of a number of predetermined states, the relative speed is monitored as an indication of relative pressure of the vehicle tires, and further wherein differences in relative speed not related to the predetermined states, and not related to differences in relative pressure, are accounted for.

Abstract: A method of detecting a partially deflated pneumatic tire on a vehicle having four tires each mounted on a wheel comprising sensing the angular velocity of each wheel by providing for each wheel, a signal generator to provide a single signal or pulse for each turn of the wheel, characterized by selecting a first wheel and measuring the time for one rotation of that first wheel, after beginning the first measurement similarly measuring the times of rotation for each other wheel, storing the times for each of the wheels for at least three rotations of each wheel and averaging the times to produce an average angular velocity value for each wheel, processing the four signals in a processor unit which subtracts the sum of the signals from one pair of diagonally opposite wheels from the sum of the signals from the other pair of diagonally opposite wheels, sensing when the magnitude of the result is between 0.05% and 0.

Abstract: A self-diagnostic method for an on-board CTIS (10) for sensing system faults and/or vehicle conditions requiring system shut down. Includes a method for preventing operations of the CITS if the pressure in the air tank has not reached a desired minimum when the vehicle speed exceeds a reference speed for a preselected period of time.

Abstract: The tire pressure sensor for motor vehicle has a reference pressure chamber (19), which is constructed as a pressure switch, including a contact diaphragm (22) and a contact pin (23). The reference pressure chamber (19) is closed toward the rim side by a ring diaphragm (28) connected at its inner rim with the housing of the pressure switch and at its outer rim (29) with the contact diaphragm (22) via a mass ring (26) for the purpose of shifting the threshold value of the pressure switch in a speed-dependent manner.

Abstract: A pressure switch for monitoring a tire pressure of a motor vehicle tire is fastened to a wheel rim and is actuated by the inflating pressure in the tire. The pressure switch comprises a reference pressure chamber which is sealed off by an electrically conductive switching diaphragm in the direction of the tire, and carries a contact pin interacting with this diaphragm. The switching diaphragm has a mass which is controlled as a function of centrifugal force in response to tire rotation such that the switching point of the pressure switch can be changed automatically as a function of vehicle speed.

Abstract: A method of detecting a deflated tire on a vehicle which includes sensing the angular velocity of each wheel and producing a signal proportional thereto, processing the four signals in a processor unit which subtracts the sum of the signals from one pair of diagonally opposite wheels from the sum of the signals from the other pair of diagonally opposite wheels, sensing when the magnitude of the result is between 0.05% and 0.60% of the mean of the two sums, comparing the signals for each of the four wheels in turn with the signals for each of the other wheels, sensing when one of said signals is different from the average of all four signals by more than 0.1% and in the event of both sensed signal factor being present, operating a warning device to indicate a tire is partially or completely deflated.

Abstract: To prevent the driver from being confused by the fact that a pseudo vehicle speed to diagnose a vehicle speed meter is indicated when a vehicle speed sensor is disconnected by an accident during vehicle travelling, a pseudo vehicle speed sensor signal is applied to the vehicle speed meter only when the vehicle speed sensor is disconnected from the vehicle speed meter and the disconnected sensor is reconnected to the meter a predetermined time period after the sensor has been disconnected from the meter. The self-diagnostic apparatus is composed of counters, flip-flops and logical gates, and is reset whenever an ignition switch is turned on.