JPH06278421A - Tire air pressure warning device - Google Patents

Abstract

PURPOSE:To enhance judgement precision by prohibiting the judgement before an undertermined coefficient to be determined on the basis of the initial state of tires is set, in a device judging the abnormalities of air pressure in the tires according to the specified operation expression on the basis of the difference between revolutions of respective tires. CONSTITUTION:Revolution detectors 7 for detecting tire revolutions F1 to F4 are provided to respective front, rear, right and left tires 1 to 4, and the output signals are sent to a controller 11 so as to judge the abnormalities of air pressure in the tires. That is, the mutual tire revolutions of respective sets of the tires 1, 3, and 2, 4 positioned on the diagonal line are separately added to each other, and then the undetermined coefficient Cx is multiplied by F1+F3 and then divided by the value which the average tire revolution is doubled, thereby the deviation value D is found. This deviation value D is compared with the deviation width Ds having the fixed width so as to judge the abnormalities of air pressure in the tires. Since the undetermined coefficient Cx is found by dividing F1+F3 by F2+F4 in drive starting of the vehicle, the judgement of air pressure is prohibited before this undetermined coefficient Cx is set.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire pressure warning device.

[0002]

2. Description of the Related Art According to a certain survey result, the tire maintenance failure rate of vehicles running on highways is surprisingly higher than the failure rate of power systems and the like. Occupies 1st place, followed by lack of tire grooves and abnormal tire wear. In addition, there are not a few drivers who have experienced punctures while traveling on high-speed vehicles,
There is an increasing demand to equip a vehicle with a tire pressure warning device or a device equivalent to it as a standard due to the fear of that, and if a tire pressure warning device can be realized at low cost, it will be used in the vehicle currently in use. There is also a request for additional equipment.

On the other hand, a sensor for detecting the air pressure of each tire of a vehicle including a lorry is provided on the vehicle side, and the air pressure of the rotating tire is detected in real time through a slip ring, radio waves, electromagnetic induction means, etc. There is a known system that attempts to inform the driver of an abnormal tire pressure due to occurrence of a flat tire or the like.

Further, in recent years, passenger cars equipped with a four-wheel ABS device and a TRC (traction control) device have shown a considerable diffusion rate along with the cost reduction of electronic-related parts. When such a four-wheel ABS device is provided, a tire rotation detector for detecting the number of tire rotations is separately provided, and a control system including each brake and a brake hydraulic differential device is provided. It is configured to be appropriately controlled according to the behavior of the vehicle.

Therefore, as in Japanese Patent Laid-Open No. 63-305011, the tire rotational speeds are summed in the diagonal direction, and the difference between the two pairs of diagonally summed values and the rotational speed difference of each tire is a predetermined value. A detection method has been proposed in which whether the tire pressure is abnormal or not is determined by determining whether or not the above is true.

[0006]

However, the above-mentioned system for detecting the tire pressure of each tire of a four-wheeled passenger car in real time has an advantage of high reliability because the tire pressure is directly detected. However, since the pneumatic pressure information is transmitted to the vehicle side through a slip ring, radio waves, electromagnetic induction means, etc., there is a drawback that the entire apparatus becomes large and expensive, and there is a problem of poor practicality.

Under such circumstances, in order to construct a tire pressure warning device without additionally mounting extra hardware-related parts as in the above proposal, it has already been provided in the vehicle equipped with the above-mentioned four-wheel ABS system. One will come to the point of effectively utilizing the detection of the tire rotation speed by the tire rotation detector.

That is, when a flat tire or the like causes a flat tire and the air pressure thereof is drastically reduced during straight running, only the outer diameter of the flat tire is smaller than that of other normal tires. This will result in an increase in the number of tire rotations as compared to other tires (because smaller diameter tires rotate more to run the same distance). This makes it possible to detect a flat tire or a tire with reduced air pressure.

Therefore, the tire pressure warning device may be configured to judge the difference in the tire rotation speeds. For this judgment, the tire rotation speeds of at least four wheels are always used as individual units. Must be detected and processed at high speed, which complicates control, and therefore some processing is required.

Further, in order to determine the difference in the number of rotations of the tire on the tire pressure warning device side as described above, it must be executed when all four wheels have the same condition during straight running. On the other hand, when the vehicle is stopped, all the tires are not in the same condition, the air pressures are different from each other, or immediately after tire replacement after flat tire repair or immediately after replacement with emergency tires with a small outer diameter. ,
This means that the tire pressure warning device cannot accurately determine the difference in tire rotation speed. That is, when all four wheels are not in the same condition, it is necessary to prohibit the tire pressure warning device from judging the difference in the number of tire revolutions.

Therefore, the tire air pressure warning device of the present invention has been made in view of the above-mentioned problems, and an object thereof is to detect a difference in the tire rotational speed in order to construct a tire air pressure warning device. In the case of making a determination on the device side, at least the tire rotation speeds for four wheels can always be detected and processed in individual units so that they can be processed when all four wheels have the same conditions.

[0012]

[Means for Solving the Problems] and

In order to solve the above problems and achieve the object, the present invention has the following constitutions. That is, it is a tire pressure warning device that determines a tire pressure abnormality from a predetermined arithmetic expression based on the rotation difference of each tire and notifies the determination result, and is determined based on the initial state of each tire prior to the determination. By providing the first undetermined coefficient setting means for setting the undetermined coefficient and the prohibition means for prohibiting the determination until the undetermined coefficient is set, the rotation of each tire is considered in consideration of the initial state of each tire. It is possible to more accurately determine a tire pressure abnormality from a predetermined calculation formula based on the difference.

Further, preferably, a tire air pressure warning device for judging tire pressure abnormality from a predetermined arithmetic expression based on the rotation difference of each tire and notifying the judgment result, and prior to the judgment, the initial state of each tire When an undetermined coefficient determined based on the above is set, and the determined undetermined coefficient is indefinite and does not satisfy the predetermined value, the undetermined coefficient is re-set by the second undetermined coefficient setting means based on the initial state of each tire again. The tire pressure is calculated from the predetermined calculation formula based on the rotation difference of each tire by removing the unstable element that is likely to occur when the vehicle starts running by prohibiting the determination until the undetermined coefficient is set. To be able to judge abnormalities more accurately.

Further, preferably, when the undetermined coefficient re-determined by the second undetermined coefficient setting means does not satisfy the predetermined value, the tire pressure abnormality is judged and the judgment result is notified to the driver and others.

Further, preferably, a tire air pressure alarm device for judging a tire air pressure abnormality from a predetermined arithmetic expression based on a rotation difference of each tire and notifying a judgment result, and prior to the judgment, an initial state of each tire. First undetermined coefficient setting means for setting an undetermined coefficient determined based on the above, and prohibiting means for prohibiting the determination until the undetermined coefficient is set and first
When the undetermined coefficient determined by the undetermined coefficient setting means does not satisfy the predetermined value, the tire pressure abnormality is determined, and the warning means continuously notifies the driver and others of the determination result.

Preferably, the first signal means for generating an initial signal for activating the first undetermined coefficient setting means for deciding the undetermined coefficient determined based on the initial state of each tire is provided. The undetermined coefficient setting means is automatically started.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic configuration plan view of a tire pressure warning device of an embodiment, in which a vehicle 20 is equipped with a four-wheel ABS device or a TRC device and the like.

For this purpose, the front, rear, left and right tires 1, 2, 3,
A rotation speed detector 7 for detecting a tire rotation speed F _n is individually provided in each of the tires 4, and the tire rotation speed necessary for controlling a well-known ABS device (anti-lock brake system) and TRC (traction control) is provided. Number F ₁ , F
₂ , F ₃ , F ₄ can be provided to the control device 11. The control device 11 also includes a warning lamp 10 for notifying a driver and others of an abnormal condition of tire pressure, and a propeller connected to the engine 5 for driving the rear tires 3 and 4 via the rear differential device 8. It is configured such that information on the rotation speed V _M of the shaft 6 is input.

As is well known, the emergency tire 9 has a width and a diameter smaller than those of a normal tire so as not to occupy the trunk space as much as possible, and is used for an emergency when the tire is punctured. is there.

In the above structure, the tire rotation speed F ₁ ,
In order to simplify the difference between F ₂ , F ₃ and F ₄ by the control device 11, the deviation value D of FIG.
The undetermined coefficient C _x in (b) is obtained. That is, after the tire rotational speeds F _n of a pair of tires 1 and 3 on the diagonal line indicated by the alternate long and short dash line in FIG. 1 and tires 2 and 4 on the diagonal line indicated by the dashed line are individually added. , F ₁ + F ₃ are multiplied by an undetermined coefficient C _x , and then divided by a value obtained by doubling the average tire rotation speed F _n to obtain the deviation value D.

The basis of the judgment process is to detect an abnormality in the tire air pressure by comparing the deviation value D thus obtained with a deviation width D _S having a predetermined width, which will be described later. High-speed tire pressure abnormality determination processing by comparison (reducing the number of processing steps in the controller)
In addition, the hardware configuration in the control device 11 can be minimized to realize the cost reduction.

The undetermined coefficient C _{x in} FIG. 2B is F ₁
It is obtained by dividing + F ₃ by F ₂ + F ₄ , and is used for returning the deviation value D to the initial state. Normally, at the start of operation of a vehicle, not all tires are in the same condition, and the air pressures are usually different from each other. Also, immediately after tire replacement after puncture repair, or after replacement with an emergency tire with a small outer diameter, or when the vehicle speed is insufficient, all the tires are not all in the same condition and the tire rotation It becomes impossible for the tire pressure warning device side to accurately judge the difference in number. Therefore, before calculating the deviation value D, after obtaining the undetermined coefficient C _x , F ₁ + F
By multiplying by ₃ , corrections are made for tire replacement after flat tire repair.

Therefore, when all the tires are normal, the undetermined coefficient C _x has a value close to “1” and does not affect the deviation value D so much. However, for example, when the tire 1 is the emergency tire 9, the value of F ₁ becomes large and becomes smaller than “1”, while the air pressures of the other tires 2, 3 and 4 are abnormally low, When the value of the undetermined coefficient C _x is extremely different from “1”, it is determined that the determination condition is not satisfied and a warning is issued as described later.

Next, FIG. 3 is a flow chart showing roughly how the tire pressure is judged to be abnormal based on the difference in the number of tire revolutions. Each flow chart to be described later cuts into the flow chart of FIG. 3 as appropriate. Is configured. In this figure, when the process is started, step S1
At step S2, processing start, tire rotation speed data, etc. are input as appropriate, and the process proceeds to step S2 to determine whether or not flag 1 is set. In this step S2,
If the flag 1 is set, the process proceeds to step S3, and it is determined whether or not the determination condition is satisfied, for example, by determining that the undetermined coefficient C _x is not an abnormal value. If it is determined that the determination condition is satisfied, the process proceeds to step S4, and tire air pressure determination is performed. On the other hand, if the flag 1 is not set in step S2, the process proceeds to step S5 and returns.

Next, FIG. 4 is a flow chart for judging whether or not the judgment condition is satisfied. Specifically, an example of operation for issuing a warning after initial setting of the undetermined coefficient C _X and abnormality detection of the undetermined coefficient C _X described above. Shows. In FIG. 4, when the process of determining whether the determination condition is satisfied is started, in step S11, the process start, the tire rotation speed data and the like are appropriately input, and the process proceeds to step S12 where the determination start switch SW is turned on. (If a manual switch is provided in the driver's seat), determine if Alternatively, in step S10 surrounded by a broken line, after the deviation value D is extremely changed, after the ignition switch is turned on,
Alternatively, after the diagnosis terminal of the self-diagnosis terminal is in the initial state, the initial state signal is automatically output to determine the satisfaction of the determination condition, and the process proceeds to step S13.

In this step S13, it is provided near the driver's seat.
Warning lamp 10 lights up and tire pressure
While notifying the driver that preparations have been completed,
Flag 0 is set to prohibit the determination. Next,
Go to step S14, undetermined coefficient C _x Vehicle is constant to get
Whether or not the vehicle is running is determined, and the undetermined coefficient C
_x If it is determined that the
Undetermined coefficient C according to equation (b) in FIG. 2_x Is calculated. Continued
In step S16, the undetermined coefficient C obtained_x Is "1"
It is not possible to judge whether it is an appropriate value that is not greatly deviated from
If it is a proper value, the process proceeds to step S21,
Previous undetermined coefficient C_x If is stored, change this value
rewrite. If it is not stored, it is newly registered.
To record. By executing the above steps, the undetermined coefficient C_x 
Is registered, the deviation value D is calculated considering the initial state.
It will be possible. Therefore, the process proceeds to step S22 and the above initial
Set the status switch to "zero" and turn the warning lamp 1
0 is turned off and air pressure judgment is started, while
Set flag 1 in roachate.

On the other hand, in step S16, for example,
Immediately after only one tire has traveled through a large road depression and the undetermined coefficient C _x is largely deviated from "1", it is determined in step S17 whether or not such an uncertain state exists. And then step S1 again
Returning to step 4, the subsequent steps are executed. If it is determined in step S17 that the undetermined coefficient C _x is not indefinite and is largely deviated from “1” of the undetermined coefficient C _x , and the tire air pressure is abnormal, the warning lamp 10 is conspicuous. Blink to to alert the driver. After this, the process proceeds to step S20 and the initial state switch is set to "zero". Further, in step S18, it is determined to be appropriate values not deviate from the "1" of undetermined coefficients C _x, performing the steps after the process returns to step S14.

As described above, the tire pressure abnormality can be accurately judged from the difference in the number of tire revolutions even after the tire is mounted for an emergency or immediately after the tire is replaced. The tire pressure abnormality can be easily notified to the driver by evaluating and determining the undetermined coefficient C _x as described above, so that it becomes possible to sufficiently deal with the problem before entering the highway, for example, and the safety can be further secured. The example of the control flow up to immediately after the start of driving has been described above. Next, when the vehicle is running, the deviation value D obtained from the above formula (the formula of (a) of FIG. 2) and the predetermined width are provided. A determination process for detecting an abnormality in tire air pressure by making a comparison with the deviation width D _S will be described.

In FIG. 5A, the vertical axis represents the deviation width D _S ,
FIG. 7 is a diagram showing a state in which a deviation value D is within a normal range with the horizontal axis representing time t. Further, FIG. 5B is a diagram showing a state in which the deviation value D is in an abnormal state. 6 (a) shows the deviation width D _S gradually increasing in proportion to the vehicle speed A, and FIG. 6 (b) shows the deviation width D _S being directly proportional to the temperature increase B of the tire to a certain degree. It is the figure which showed the mode which makes it increase to B` and does not change after that.

First, in FIG. 5A, the deviation value D is positive when the value of F ₁ + F ₃ is larger than the value of F ₂ + F ₄ as described above, and when it is the opposite. Since it is negative, the deviation width D _{S in the} range between the positive D _S1 and the negative D _S1 in the figure (shown by the alternate long and short dash line) is the normal tire pressure range, and the deviation value D obtained after the vehicle has run normally As indicated by a solid line and a broken line in the figure, it is determined to be normal if the determination is within the predetermined period T.

On the other hand, in FIG. 5B, the range (illustrated by the one-dot chain line) in which the deviation value D is sandwiched between the positive D _S1 and the negative D _S1 is set within the predetermined time width (cycle) T or If it is out of the lower side, it is judged that the tire pressure is abnormal. That is, in FIG. 5B, the positive D of the deviation value D
_If the integral value ΣD in the range exceeding _S1 becomes equal to or more than a predetermined value within the predetermined cycle T, it is determined that the tire air pressure is abnormal, and after the negative value D _S1 such as the deviation value D ′ is exceeded, the positive value is rapidly increased.
_{Even if S1} is exceeded, it is determined that the tire pressure is abnormal.

Next, in each of FIGS. 5A and 5B, the positive / negative deviation width D _S2 shown by the broken line gradually increases in proportion to the increase of the vehicle speed A, as shown in FIG. 6A. I am trying. By changing the deviation width D _S according to the vehicle speed A in this manner, the adverse effect of fixing the deviation width D _S is eliminated. That is, as the vehicle speed A increases, the deviation value D also tends to increase, and the damage at the time of puncture increases. Therefore, the deviation width D _S2 is set larger than the deviation width D _S1 , and the damage is increased. I try to make it less.

Further, as shown in FIG. 6B, the deviation width D _S2 is set so as to be gradually increased to the temperature B ′ in direct proportion to the tire temperature rise B, and not to change thereafter.
It is possible to make a determination in consideration of an increase in tire air pressure due to an increase in temperature. Here, as parameters other than the vehicle speed A and the tire temperature B shown in FIG. 6, a value determined by the vehicle height sensor of the active suspension, which is a load determined by the number of occupants, and the degree of turning. There are yaw turning moment values to be detected, longitudinal G, lateral G, and the like.

As described above, the deviation width D _S2 is appropriately changed in consideration of various factors without fixing the deviation width D _S , so that the tire air pressure can be practically determined according to the running condition of the vehicle. Can be run to.

Next, FIG. 7 is a determination flow chart based on the diagram shown in FIG. 5B. When the air pressure determination is started after it is detected that there is no abnormality in the undetermined coefficient C _X , In step S30, the judgment timer is started,
Set "4" in the flag. After this, the process proceeds to step S31, where the deviation value D obtained by the above equation is the positive deviation width D.
If it is larger than _S, if it is larger than _S, it is abnormal. Therefore, the process proceeds to step S32, and it is determined whether 2 is set in the flag. If 2 is set, step S33 is executed. Then, the _k integrated value S _k is set to a value obtained by adding 1 to the previous integrated value S _{k -1} , and then the process proceeds to step S35 to set the flag to "2". If 2 is not set in the flag in step S32, the integral value S _k is set to zero and the process proceeds to step S35. In step S35, the process proceeds to step S41, and it is determined whether a predetermined time (cycle) T has elapsed.

On the other hand, in step S31, the deviation value D
Is determined to be smaller than the positive deviation width D _S , the process proceeds to step S36, and it is determined whether the deviation value D is smaller than the negative deviation width D _S. In this step S36,
When it is determined that the deviation value D is smaller than the negative deviation width D _S , it is determined that the abnormality is abnormal at least at the moment of the determination.
Since it may be due to a mere noise factor, in order to wait for a sufficient time for determination, the process proceeds to step S37 and it is determined whether "3" is set in the flag. If "3" is set in the flag in step S37,
In step S38, the integrated value ΣS _{k is set} to the previous integrated value Σ
After setting the value obtained by adding 1 to S _{k -1} , the process proceeds to step S41 and waits for the time T to elapse.

On the other hand, if it is determined in step S37 that "3" is not set in the flag, step S39
In step S40, the flag is set to "3", and in step S40, the integral value ΣS _k is set to "zero". Then, the process proceeds to step S41 and waits for the time T to elapse. When the time T elapses, the process proceeds to step S42, while the process returns to step S31 until the time T elapses. In step S42, the flag is set to "4", the determination result of the determination result based on the above-described series of steps is prepared, and step S42 is performed.
When it is determined that the integrated value S _k or the integrated value ΣS _k exceeds the predetermined value in 43, the tire pressure abnormality is determined in step S44. If it is determined that the value is not equal to or larger than the predetermined value, the process returns.

When the tire pressure abnormality is determined in step S44, the process proceeds to step S45, in which the warning lamp is turned on, while in the case of the vehicle equipped with the ABS device, the brake operation is automatically controlled to the safe side. To do. Similarly, in the case of the vehicle equipped with the TRC device and the vehicle equipped with the 4WS device, the control is automatically performed so as to be on the safe side, and the control is continued until the tire is returned to the normal state.

By controlling as described above, when the detection of the tire rotation speed is effectively used, it is possible to accurately determine the tire pressure abnormality by removing the noise factor.

Next, FIG. 8 is a puncture determination flow chart. When the deviation value D deviates greatly from the deviation width D _S as shown by the broken line in FIG. 5B, the tire This is for performing the puncture determination because the puncture state is caused by the sudden decrease in air pressure. In FIG. 8, when the process is started, in step S50,
The absolute value of the deviation value D and the absolute value of the deviation width D _S are compared, and if the deviation value D is larger than the absolute value of the deviation width D _S , the process proceeds to step S51 and waits for the elapse of time T to proceed to step S52. In this step S52, steps S50 and S51
If it is determined that the deviation value D is still larger than the absolute value of the deviation width D _S even after the judgment is made whether or not the deviation width D _S has been executed a predetermined number of U times, the step S53
Then, the puncture judgment is performed. As a result, while the warning lamp is turned on, in the case of the vehicle equipped with the ABS device, the brake operation is automatically controlled so as to be controlled to the safe side. Similarly, in the case of the vehicle equipped with the TRC device and the vehicle equipped with the 4WS device, the control is automatically performed so as to be on the safe side, and the control is continued until the tire is returned to the normal state. By performing the puncture determination as described above, it is possible to accurately perform the puncture determination by determining the air pressure abnormality that occurs within the predetermined time T so as not to make an erroneous determination.

According to each of the flow charts described above, the driver can judge the tire pressure abnormality from the lighting of the warning lamp, which is sufficiently practical. It is more preferable if it can be specified without specifying. Therefore,
In order to identify the tire with abnormal air pressure and notify the driver, the processing by the abnormal tire identifying flow chart in FIG. 9 is performed, and the warning lamps shown in FIG. 10 are displayed.

Therefore, the process for identifying the abnormal tire is started.
Then, the process proceeds to step S60 in FIG.
Of the deviation value D obtained by using the equation (a) of FIG.
Value and deviation width D_s And compare F₁ + F₃ Than the value of F
₂ + F_Four Value is larger and deviation value D is negative deviation width D_s Yo
If it is determined that it is greater than ₂ 
+ F_Four Either one of tires 2 and 4 showing the rotation of
It is judged that something is wrong and it is a flat tire.

Following this, in step S65,
The rotational speed and the engine of the tire 4 driven via the differential device 8
Jin speed V_M And the final reduction ratio multiplied by the tire
Number of revolutions F of 4_Four Is compared, and the rotation speed F of the tire 4 is compared.
_Four Is the engine speed V _M Thailand if greater
In step S67, the ya 4 is in a flat state.
After making a determination, the process proceeds to step S68. This step S68
Then, as will be described later, the display as shown in FIG. 10 is displayed.
Tire 4 is flat against the driver
Let me know. On the other hand, in step S65, the tire 4
Number of revolutions F_Four Is the engine speed V_M Smaller field
If the tire 2 is in a flat state, step S6
In step 7, the process proceeds to step S68 and the same display is made.
To do.

In step S60, the deviation value D
Value and deviation width D_s And compare F ₁ + F₃ Than the value of
F₂ + F_Four Value is smaller and deviation value D is negative deviation width D_s 
If it is determined that the difference is larger than the
Difference value D and positive deviation width D_s And the deviation value D is positive
Difference width D_s If it is determined to be greater than
Go ahead, F₁ + F₃ One of the tires 1 and 3 showing the rotation of the
It is judged that there is a puncture due to an abnormality in the tire of
It On the other hand, in step S61, the deviation value D is the positive deviation.
Width D_s If the difference is smaller than
Therefore, the process proceeds to step S62 and the system fails.
Is output and "X" is set in the flag to return to the normal flow.
Give back.

Subsequent to step S63, the rotational speed of the tire 3 driven via the differential device 8 and the engine rotational speed V _M
And the value obtained by multiplying the final reduction ratio by the number of revolutions of the tire 3 F ₃
When the rotation speed F ₃ of the tire 3 is larger than the engine rotation speed V _M, it is determined in step S67 that the tire 3 is in a punctured state, and the process proceeds to step S68 to ask the driver Informs that the tire 3 is in a flat state. On the other hand, if the rotation speed F ₃ of the tire 3 is smaller than the engine rotation speed V _M in step S66, it is determined in step S67 that the tire 1 is in the punctured state, and step S68 is executed.
Proceed to and display the same.

Next, FIG. 10A is a conduction diagram of the warning lamp display of the first embodiment, FIG. 10B is a display example of the second embodiment, and FIG. 10C is a display example of the third embodiment. And, (d) is a schematic diagram showing a display example according to the fourth embodiment, respectively. First, in FIG. 10A, the tire 1 or 3 punctured by the flow chart in FIG. 9 described above.
When the above is specified, the warning lamp display is displayed once at a predetermined time interval as shown in the figure to inform the driver that the tire 1 is in a punctured state. In addition, when the tire 3 is flat, a display for three times is displayed at a predetermined time interval,
Notify the puncture state. Thereafter, similarly, the flashing of two times and four times is similarly performed, and the punctured tire is notified. With such a display method, a flat tire can be displayed by providing only one warning lamp 10 used as described above in the flow chart of FIG.

Next, FIG. 10 (b) shows an example of displaying a flat tire using a so-called 7-segment display. Further, FIG. 10C shows the tire 1 with F
L, tire 2 is FR, tire 3 is RR, tire 4 is RL
As an example, a printed display is made on the display plate, and a lamp is arranged on the back surface of the display plate to directly display the flat tire. FIG. 10D shows an example in which the characters are printed and displayed as pictograms, the lamps are respectively provided on the back surface of the display plate, and the tires having flat tires are directly displayed.

By identifying and displaying the punctured tire as described above, for example, when a puncture occurs, it is not necessary to go out of the vehicle and check the punctured tire.

In each of the embodiments described above, the rotation speed obtained from the rotation detector 7 is used to detect the difference in the tire rotation speed. However, the invention is not limited to this, and the movement of each tire may be changed. There is a method of judging from the distance, which can be selected appropriately.

[0050]

As described above, according to the present invention, when the difference in tire rotational speed is determined by the tire air pressure warning device to configure the tire air pressure warning device, at least four tire rotation speeds for at least four wheels are detected. It is possible to provide a tire air pressure alarm device that can always detect and process in individual units, and can process when all four wheels have the same condition to accurately detect tire air pressure.

[Brief description of drawings]

FIG. 1 is a schematic configuration plan view of a tire pressure warning device.

2A and 2B are diagrams showing an equation for obtaining a deviation value and an undetermined coefficient, FIG. 2A is a diagram showing an equation for obtaining a deviation value D, and FIG. 2B is a diagram showing an equation for finding an undetermined coefficient C _X. .

FIG. 3 is a flow chart that roughly shows how a tire pressure abnormality determination is performed based on a difference in tire rotational speed.

FIG. 4 is a flow chart for determining whether or not a tire air pressure determination condition is satisfied.

FIG. 5 is a comparison diagram of the deviation value D and the deviation width D _S ,
(A) is a diagram showing the deviation width D _S on the vertical axis and the time t on the horizontal axis, showing a state in which the deviation value D is within the normal range, and (b) is a diagram showing the deviation value D in an abnormal state. FIG.

FIG. 6 is a correspondence diagram of the deviation width D _S and the vehicle state,
(A) shows that the deviation width D _S gradually increases in proportion to the vehicle speed A, and (b) of FIG. 6 makes the deviation width D _S directly proportional to the temperature increase B of the tire partway and increases it to the temperature B ′. FIG. 6 is a diagram showing a state where no change is made thereafter.

7 is a determination flow chart based on the diagram shown in FIG. 5 (b).

FIG. 8 is a flowchart for puncture determination.

FIG. 9 is a puncture-specific flow chart.

FIG. 10 is an embodiment of an alarm device, (a) is an energization diagram of the first embodiment with a warning lamp display, and (b) is a second embodiment.
FIG. 8 is a schematic diagram showing a display example according to the embodiment, (c) a display example according to the third embodiment, and (d) a display example according to the fourth embodiment.

[Explanation of symbols]

1, 2, 3, 4 ... Tire, 6 ... Propeller shaft, 7 ... Rotation speed detector, 8 ... Differential device, 9 ... Emergency tire, 10 ... Warning lamp, 11 ... Control device, D ... Deviation value, D _sn ... deviation width, C _X ... undetermined coefficients, F _n ... number of tire revolutions, V _M ... engine speed, T ... duration (period), a ... vehicle speed is B ... tire temperature.

Claims (5)

[Claims] 1. A tire pressure warning device for judging tire pressure abnormality from a predetermined arithmetic expression based on the rotation difference of each tire and notifying the judgment result, wherein prior to the judgment, the initial state of each tire is determined. A tire air pressure warning device comprising: a first undetermined coefficient setting means for setting an undetermined coefficient determined based on the above; and a prohibition means for prohibiting the determination until the undetermined coefficient is set. 2. A tire air pressure alarm device for judging tire pressure abnormality from a predetermined arithmetic expression based on a rotation difference of each tire and notifying the judgment result, wherein the initial state of each tire is prior to the judgment. A second undetermined coefficient that is set again based on the initial state of each tire when the undetermined coefficient determined based on the above is set, and the determined undetermined coefficient is indefinite and does not satisfy the predetermined value. A tire pressure warning device, comprising: coefficient setting means; and prohibiting means for prohibiting the determination until the undetermined coefficient is set. 3. When the undetermined coefficient re-determined by the second undetermined coefficient setting means does not satisfy a predetermined value, a tire pressure abnormality is determined and the determination result is notified. Item 3. A tire pressure alarm device according to item 2. 4. A tire air pressure alarm device for judging tire pressure abnormality from a predetermined arithmetic expression based on the rotation difference of each tire and notifying the judgment result, wherein the initial state of each tire is prior to the judgment. First undecided coefficient setting means for setting an undecided coefficient determined based on the undetermined coefficient, prohibiting means for prohibiting the determination until the undecided coefficient is set, and the undecided coefficient determined by the first undecided coefficient setting means A tire air pressure warning device, comprising: a warning unit that judges a tire pressure abnormality when the coefficient does not satisfy a predetermined value and continuously informs the judgment result. 5. An initial signal means for generating an initial signal for activating a first undetermined coefficient setting means for deciding an undetermined coefficient determined based on an initial state of each tire. Item 1. A tire pressure warning device according to item 1, 2 or 4.