This invention is related to a system calculating and displaying tire pressures needed in vehicles. Prior art

Air pressures of tires should be adjusted according to the vehicle's own weight and to the load it carries in all rubber tired vehicles from private cars to trucks. Wrong tire pressure the vehicle has affects the drive, performance, comfort, safety and tire life of the vehicle negatively.

The tire pressures that may change in time by pressure decrease occurring in the tires as a result of changing of the total weight of the vehicle depending on the load or may also change in time by different ways are required to be adjusted again. In that situation; a system informing about how much tire pressure is required is needed. Because drivers generally need to adjust the tire pressure again when the decrease in the tire pressure reaches a distinguishable level or when they realize the change in the interaction between the tire and road (sound, maneuver difficulty/easiness etc.). So, the change in the tire pressure is required to reach a physically perceivable level, however; this may cause dangerous situations.

Generally, drivers do not behave sensitively about how much pressure is necessary. Change in the tire pressures is generally required due to the session changes. Also, changing tire pressures is required especially in case of increasing/decreasing of the vehicle load. However, this situation is ignored by drivers. Because this situation causes the difficulties of monitoring the variables (e.g. outer environment temperature, weight of the vehicle, its distance to the ground) regularly and of calculating pressure by starting these variables. Because of changing of the pressure value needed in the tire according to the parameters such as season, vehicle load; the driver may find the necessary pressure value by doing calculations and by using tables if he is interested and has information about the matter on his own. Therefore, spending time for this regularly and having information about the calculations are required. In addition; the automobile manufacturers suggest tire pressures for curb weights of the vehicles according to the seasons, mainly summer and winter.

In the patent document of EP0768193 which is one of these systems, a system for calculating the lowness of the tire pressure is mentioned. Change in the tire pressure is calculated according to the relations of the wheels between each other in this document. In another patent document of KR20040023404 in the state of the art, a device and method for monitoring air pressure of tires are mentioned.

The system in another patent document of FR2545225 in the state of the art compares a predetermined height value of the vehicle with the value calculated by the distance sensors. However, how much inflating/deflating of tires is needed cannot be calculated good enough and the necessary pressure cannot be transmitted to the last user, namely; to the driver such that he understands although the tires have an inappropriate pressure for the conditions in the systems in the state of the art.

Brief description of the invention The aim of this invention is to perform the calculation of the tire pressure needed in the vehicles and its suggestion to the driver.

The disclosed system of the invention calculates the necessary pressure with some calculations from the distances it measures via distance sensing units. Also, the need for change in the tire pressure according to the seasons is calculated by the disclosed system of the invention via temperature sensing units.

One of the important sides of the invention is that the output of the distance sensing unit may be used for different aims. Determination of the suspension displacements, angle of bank and angle of pitch in the vehicle is possible via these distance sensing units. This information can be used in lots of calculations about the vehicle dynamics and control. Detailed description of the invention

Description of the figures:

Figure 1: It is the block diagram of the disclosed system of the invention and the bottom view of the vehicle.

Figure 2: It is the flow diagram showing the steps of the working method of the disclosed system of the invention.

Description of the references in the figures:

The parts in the attached figures are numbered respectively for the aim of this invention and the equivalents of these numbers and letters are given below.

10. Tire pressure suggestion system 11. 1. distance sensing unit

21. 2. distance sensing unit

31. 3. distance sensing unit

41. 4. distance sensing unit

12. Control unit

13. Display unit

14. Temperature sensing unit

T: Wheel hn: The distance between the ground and the ground facing side of the bottom of the vehicle measured by the 1. distance sensing unit(l 1) ho: The distance between the ground and the ground facing side of the bottom of the vehicle measured by the 2. distance sensing unit(21) ho: The distance between the ground and the ground facing side of the bottom of the vehicle measured by the 3. distance sensing unit(31) hf4: The distance between the ground and the ground facing side of the bottom of the vehicle measured by the 4. distance sensing unit(41)

In the invention, the ground is the place on which the vehicle is present.

The front side of the vehicles comprising said system(lO) is the side in which the steering wheel, namely; the driver seat is present in the vehicle. The vehicle comprises a front axle at this front side. The rear side of the vehicles is the side in which the rear seats or brake lamps are present. The vehicle comprises a rear axle at the rear side.

The disclosed system(lO) of the invention comprises at least one distance sensing unit(l l, 21, 31, 41) positioned to the ground facing side of the vehicle bottom at the front side and/or rear side, a control unit(12) and a display unit(13) suggesting the necessary tire pressure to the driver. In the preferred embodiment, the system(lO) comprises distance sensing unit(l 1, 21, 31, 41) for measuring the distance between the ground and the ground facing side of the bottom of the vehicle. In an embodiment of the disclosed system(lO) of the invention, the distance sensing units(l l, 21, 31, 41) the system(lO) comprises are sensors. The distance sensing units(l l, 21, 31, 41) measure the distance between the ground and the ground facing side of the bottom of the vehicle. In a preferred embodiment, the system(lO) comprises at least two distance sensing units(l l, 21, 31, 41). In another embodiment of the invention, total four distance sensing units(l 1, 21, 31, 41) are positioned to the front and rear corners at the ground facing side of the vehicle bottom as two for each. The distance sensing units(l l, 21, 31, 41) are positioned at the ground facing side of the bottom of the vehicle and preferably at around the wheels(T).

In the preferred embodiment of the invention, 1. and 2. distance sensing units(l l, 21) are positioned at the ground facing side of the vehicle at the front side of the system(lO). The distance sensing units(l l, 21) at the front side are positioned preferably at opposite sides to each other. In the preferred embodiment of the invention, 3. and 4. distance sensing units(31, 41) are positioned at the ground facing side of the vehicle at the rear side of the system(lO). The distance sensing units(31, 41) at the rear side are positioned preferably at opposite sides to each other. In another embodiment of the invention, the distance sensing units(l l, 21, 31, 41) are positioned at the ground facing side of the vehicle at the bottom of the vehicle and at opposite sides to each other. In another embodiment of the invention, these units(l l, 21, 31, 41) may be positioned at the front and rear bumper of the vehicle and preferably at the ground facing side of the bumper. In an embodiment of the disclosed system(lO) of the invention, the system(lO) comprises at least one temperature sensing unit(14). In the preferred embodiment of the invention, the temperature sensing unit(14) measures the temperature of the outer environment. In addition, the temperature sensing unit(14) transmits the temperature information it measures to the control unit(12). In an embodiment of the disclosed system(lO) of the invention, the control unit(12) the system(lO) comprises is an electronic control unit (ECU).

The disclosed system(lO) of the invention is adapted such that it works according to the method(lOO) steps below and it displays the tire whose pressure is low to the driver and suggests the necessary pressure according to this: - Measuring the distances of hn, ho, ho, hf ₄ by the distance sensing units(l 1, 21, 31, 41)

(101) Transmitting the taken distance measurements(hfi, ho, ho, hf ₄ ) to the control unit(12) (102)

Comparing the distances (hn with ho) two distance sensing units(l l, 21) positioned at the front of the vehicle measure and the distances (ho with hf ₄ ) two distance sensing units(31, 41) positioned at the rear of the vehicle measure and calculating their differences (difference of hfi -ho and difference of hf3-hf ₄ ) by the control unit(12) (103) Writing which tire has low pressure and the necessary value of said tire pressure to the display unit(13) if the difference of hfi -ho and/or the difference of hf3-hf ₄ is higher than a predetermined value(104)

- Calculating the distances of the front axle to the ground and of the rear axle to the ground by the control unit(12) if the differences of hfi -ho and of hf3-hf ₄ are lower than a predetermined value(105)

Calculating the weight per each wheel(T) by starting from the distances of the axles to the ground by the control unit(12) if the differences of hfi -ho and of hf3-hf ₄ are lower than a predetermined value(106)

Calculating the necessary pressures for front and rear tires from the relation of weight- tire pressure by the control unit(12) if the differences of hfi -ho and of hf3-hf ₄ are lower than a predetermined value(107)

Suggesting these pressures to the driver via the display unit(13) if the differences of hfi- ho and of hf3-hf ₄ are lower than a predetermined value(108).

In the method(lOO), the control unit(12) calculates the different of hfi-hf2 by considering hfi and ho from the distances of hfi, ho, ho and hf ₄ in the 103. step. Also, it calculates the difference of hf3-hf ₄ by considering ho and hf ₄ .

In the 104. step, the tire pressure of the vehicle will be low if the distances of hfi- ho and/or of hf3-hf ₄ are higher than a predetermined value. Therefore, the control unit(12) gives warning in case of low tire pressure or flat tire by calculating the differences of hfi -ho or of hf3-hf ₄ . Because it is understood from being high of these differences that a tire pressure at the front and/or rear side of the vehicle is very low or the tire is flat. The tire having low pressure is displayed by the display unit(13) if the difference between hfi and ho calculated by the control unit(12) is higher than a predetermined value.

The method(lOO) continues with the 105. step if the distances of hfi- ho and/or of hf3-hf ₄ are lower than a predetermined value. In the 105. step, the arithmetic mean of the distance information(hfi, ho) obtained from two distance sensing units(l l , 21) at the front side is calculated by the control unit(12) in case that the difference between hfi and ho is low. Similarly, the arithmetic mean of the distance information(l¾3, hf ₄ ) obtained from two distance sensing units(31, 41) at the rear side is calculated by the control unit(12) in case that the difference between ho and hf ₄ is low. The control unit(12) accepts the arithmetic mean of hfi and hf2 as the distance of the front axle to the ground. Similarly, it accepts the arithmetic mean of ho and hf ₄ as the distance of the rear axle to the ground.

The control unit(12) can calculate the weight per a single wheel(T) instantaneously according to the means of the distances(hfi, ho, ho, hf ₄ ) measured before (namely, according to distances of the front/rear axles to the ground) as follows in the calculation mentioned in the 106. step.

When the vehicle does not have load, the static force balance is written as follows:

The force balance at any moment is as follows:

mf _j g = k _eq . _j hf _j (2)

The unknown n mass is calculated by using equation (1) and (2) as follows:

niij = half of the mass carried by the front/rear axle of the vehicle when the vehicle does not have load (the mass per each front/rear wheel(T) of the vehicle when the vehicle does not have load) nifj = half of the mass carried by the front/rear axle of the vehicle at any moment (the mass per each front/rear wheel(T) of the vehicle at any moment) hij = the distance between the front/rear axle and the ground when the vehicle does not have load (the distance sensing unit(l l, 21, 31, 41) measurement or ex-factory information) hfj = the distance between the front/rear axle and the ground at any moment (the distance sensing unit(l l, 21, 31, 41) measurement) keq-j = equivalent of the suspension and tire stiffness constants for each axle g = gravitational acceleration j = axle code (x: front axle, y: rear axle; e.g. hf _x =the distance between the front axle and ground at any moment)

The distances of the front axle to the ground (hf _x ve hi _x ) are used in the calculation of weight for two wheels(T) at the front side and the distances of the rear axle to the ground (hf _y ve hi _y ) are used in the calculation of weight for two wheels(T) at the rear side.

In the 107. step, the necessary tire pressures according to the weight of the vehicle are given as tables. These tables are normally calculated according to a specific formula. A curve is fitted to the graph obtained by using the formula in case of knowing this formula or by using table values in case of not knowing the formula. The weight and tire pressure relation is obtained mathematically by using the equation obtained from the fit curve. However, the tire pressure and weight relation changes according to the tire types. Namely, there is not only one table. Therefore, the mathematical pressure-weight relations obtained from the fitted curves are different formulas from each other according to the tire types. So, the calculations are carried out according to the tire type. In the 107. step, the necessary tire pressure is calculated instantaneously by the control unit(12) by using m j mass or weight of the vehicle (»¾ ^■ g) in the weight - tire pressure equation. The control unit(12) transmits the necessary tire pressure values to a display unit(13) for showing them to the driver for each tire respectively according to the values calculated instantaneously. Also, the control unit(12) calculates the necessary tire pressure value by using the weight - pressure relation in case of difference between mj and ttiij and transmits this pressure value to a display unit(13) for informing the driver.

The weights per two wheels(T) at the front are equal to each other and this is half of the weight carried by the front axle because the half of the weight carried by the front axle is equal to the weight carried by one wheel(T) at the front (Half of the weight carried by the front axle = weight carried by the right front wheel(T) = weight carried by the left front wheel(T)). Similarly, the weights per two wheels(T) at the rear are equal to each other and this is half of the weight carried by the rear axle because the half of the weight carried by the rear axle is equal to the weight carried by one wheel(T) at the rear (Half of the weight carried by the rear axle = weight carried by the right rear wheel(T) = weight carried by the left rear wheel(T)). In this case; when the calculations for passing from the weights to pressure are carried out, the result is as follows: The pressures of the front tires (right front and left front) are equal to each other and the pressures of the rear tires (right rear and left rear) are equal to each other. To summarize, firstly the weight per each wheel(T) is found from the calculated distances(hfi, ho, f3, hf ₄ ) in the invention. Passing from the weight to pressure is done with the calculations.

In an embodiment of the disclosed system(lO) of the invention; in case that the pressure difference between the known tire pressure for nnj and the calculated tire pressure for nifj is only an integer according to any pressure unit (e.g. psi, bar etc.), this pressure difference is transmitted by the control unit(12) to the display unit(13) for informing the driver. For example; if the pressure difference is at least 1 psi, the necessary tire pressure will be transmitted by the control unit(12) to the display unit(13) for informing the driver. If the weight difference does not cause an integer change in the calculated pressure value, for example if the the value of change in pressure is lower than 1 psi, this change will not be reflected to the display unit(13). The precision of the pressure value which the driver is informed about is adjusted in the display unit(13) according to the precision in the displays of the devices pumping air or to the precision determined by the vehicle manufacturers.

In a preferred embodiment of the invention, the temperature sensing unit(14) measures the temperature of the outer environment and transmits to the control unit(12) in the 107b. step.

In this preferred embodiment of the disclosed system(lO) of the invention, the temperature parameter is also included in the calculation together with the weight/pressure relation by the control unit(12) in the 107. step. The control unit(12) adds this information to its calculations. One of two methods may be followed for this calculation: a) The outer environment temperature - tire pressure relation obtained by using the tables giving appropriate tire pressures according to the outer environment temperatures is formulated. Tire pressure corresponding to any temperature is found directly with this formula. b)Two end temperature values for summer and winter and appropriate tire pressure values for these temperature values are taken. The pressure values corresponding to the temperatures between these two end values are calculated via the interpolation technique and the pressure values staying out of these two end values are calculated via the extrapolation technique.

Distance measurement may be performed by the distance sensing unit(l l, 21, 31, 41) continuously while the vehicle is on the move, while the vehicle is in park and works or during a specific time after the first move in the 101. step. However, in the preferred embodiment of the disclosed system(lO) of the invention, the distance measurement is carried out during a specific time period after the first movement of the vehicle in the 101. step. Because this option does not comprise negativities such as changing the pressures of the tires by heating the tires during the drive and as surface differences in the park place. This time period is a predetermined period, for example it may change between 10 seconds and 5 minutes. The automobile manufacturer may decide this. As a result, the calculation algorithm in the control unit(12) calculates the mean of the measurements taken during the specific time and adds it to the calculation in the 103. step. This mean is calculated via a simple statistical method called as moving average. When the mean value is fixed in a specific tolerance interval, the distance value obtained from that distance sensing unit(l l, 21, 31, 41) is determined and taking measurement from that distance sensing unit(l l, 21, 31, 41) is stopped from now on. In addition, calculating the vehicle weight with/without load provides a simplicity for calibration which may be needed because of suspension system changing in time etc. in the disclosed system(lO) of the invention. The suspension systems change with the aging vehicle. The distance values taken from a vehicle with a specific weight which has a new suspension system are different from a vehicle having an old suspension system. The differences occurring in the suspension system because of accident and repair may also cause this difference. As another point, the distance between the vehicle body and ground changes with the changing wheel(T) diameter in case of changing the ex-factory rims and of mounting a rim with different diameter. In the situations like that, changing the predetermined distance values (with/without load), namely; distance calibration of the suggestion system(lO) is needed. Industrial applicability

Said invention has an application area in the automotive industry. It may be produced as integrated with the vehicles and also it may be mounted later to the vehicles which is ex-factory and do not comprise this system(lO) such as park sensors mounted to the vehicles later. It may be applied to the vehicles with at least four distance sensing unit(l l), cabling, control unit(12) comprising the calculation and communication software, display unit(13) and preferably temperature sensing unit(14).

The invention is not limited with the disclosed embodiments above, a skilled person in the art can produce different embodiments of the invention easily. They should be evaluated within the scope of invention protection demanded with claims.