JP3286004B2 - Tire pressure warning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art According to a result of a survey, it has been found that the defective rate of tire maintenance of a vehicle running on a highway is unexpectedly higher than that of other power systems and the like. And is the first place, followed by tire groove shortage and abnormal tire wear. In addition, many drivers experienced punctures while driving high-speed vehicles,
The fear at that time also works, and there is an increasing demand to equip the vehicle with a tire pressure alarm device or a device equivalent to the tire pressure alarm device. If the tire pressure alarm device can be installed at low cost, the vehicle currently in use There is also a request to add additional equipment. On the other hand, a system for detecting the air pressure of each tire of a vehicle including a lorry is provided on the vehicle side, and a system that detects the air pressure of the rotating tire in real time via a slip ring, a radio wave, electromagnetic induction means, or the like is known. This system is known, and attempts have been made by the system to inform a driver of a tire pressure abnormality due to a puncture or the like.

In recent years, with the reduction in the cost of electronic components, passenger cars equipped with a four-wheel ABS device and a TRC (traction control) device have become quite popular. When such a four-wheel ABS device or the like is provided, a tire rotation detector for detecting the number of rotations of the tire is separately provided, and a control system constituted by each brake and a brake hydraulic differential device is provided. It is configured so as to be appropriately controlled according to the behavior of the vehicle.

Accordingly, as disclosed in Japanese Patent Application Laid-Open No. 63-305011, the tire rotational speeds are summed diagonally, and the difference between the two sets of diagonal total values and the difference between the rotational speeds of the respective tires is a predetermined value. A detection method has been proposed in which the above is determined to detect a tire air pressure abnormality.

[0005]

However, according to the above-mentioned system for detecting the air pressure of each tire of a four-wheel passenger car in real time, the tire air pressure is directly detected, so that the system has an advantage of high reliability. However, since the air pressure information is transmitted to the vehicle via a slip ring, radio waves, electromagnetic induction means, and the like, the whole device is disadvantageously large and expensive, and has a problem of poor practicality.

Under these circumstances, in order to configure a tire pressure alarm device without additionally mounting extra hardware-related parts, a tire rotation detector already provided in a vehicle equipped with the above-described four-wheel ABS device or the like is used. The above-mentioned proposal for effectively utilizing the detection of the tire rotation speed has been made.

That is, if a puncture or the like occurs in a specific tire during straight running and the air pressure decreases sharply, only the outer diameter of the punctured tire becomes smaller than that of other normal tires. The tire rotation speed will increase compared to a normal tire (since a small diameter tire rotates more to travel the same distance). For this reason, the principle that enables detection of a punctured tire or a tire with reduced air pressure is used.

Therefore, it is sufficient that the difference in the number of tire rotations is determined on the side of the tire pressure warning device. For this determination, the number of rotations of the tires of at least four wheels is always determined in individual units. , And high-speed processing must be performed, which complicates control. Therefore, some processing is required. From this, the difference between the tire rotations on the diagonal line is added, the difference between them is obtained, the deviation is obtained by dividing the average by twice, and the comparison with the fixed comparison value is performed. In such a case, it is conceivable to determine a tire air pressure abnormality when the predetermined value is exceeded.

[0009] However, if this comparison value is fixed, it is impossible to make an optimal judgment on the running state of the vehicle. Thus, for example the larger the vehicle speed is, of course results speed increases ing, since the variation of the deviation value is also increased, can not be accurately tire pressure determination will be above a fixed comparison value.

Therefore, the tire pressure warning device of the present invention has been made in view of the above-mentioned problems, and an object of the invention is to provide a tire pressure warning device in which a tire rotation speed difference is determined on the tire pressure warning device side. The optimum tire pressure is determined according to the running state of the vehicle.

[0011]

Means for Solving the Problems and

In order to solve the above-mentioned problems and achieve the object, the present invention has the following arrangement. That is, a tire pressure warning system that determines abnormality of tire air pressure, it outputs an alarm by using the detection signal of the wheel speed sensor for detecting a rotational state of each tire of the vehicle individually, about the rotational difference between the tires
Determining a tire pressure abnormality by comparing a deviation value based on the calculated value with a deviation width having a predetermined upper limit value and a predetermined lower limit value; a vehicle speed detecting unit detecting a vehicle speed; A predetermined value changing means for changing the upper limit value and the lower limit value so that it is difficult to determine that the air pressure is abnormal as the vehicle speed becomes higher.
In the step, the deviation width increases as the vehicle speed increases.
So as to increase the upper limit and decrease the lower limit.
Correct .

The present invention has the following configuration. Immediately
That is , a tire pressure warning device that determines a tire pressure abnormality using a detection signal from a wheel speed sensor that individually detects a rotation state of each tire of a vehicle, and outputs a warning, wherein a value related to a rotation difference between the tires is provided. Determining a tire pressure abnormality by comparing a deviation value based on the above and a deviation width having a predetermined upper limit value and a lower limit value; and determining the deviation width, when the tire temperature is lower than a predetermined temperature, the tire temperature. And a predetermined value changing means for setting the value to increase as the value increases.

[0013]

[0014]

[0015]

[0016]

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 plan view of a tire pressure warning device according to an embodiment. In this drawing, a vehicle 20 is equipped with a four-wheel ABS device to a TRC device and the like.

For this purpose, the front, rear, left and right tires 1, 2, 3,
The 4 and the rotational speed detector 7 are provided individually for detecting the tire rotation speed F _n, tire rotation required for the control of a known ABS device (anti-lock braking system) and TRC (traction control) The numbers F ₁ , F
₂ , F ₃ , and F ₄ can be provided to the control device 11. The control device 11 also includes a warning lamp 10 for notifying a driver or the like of an abnormal condition of the tire pressure, and a propeller connected to the engine 5 for driving the rear tires 3 and 4 via the rear differential device 8. and it is configured so that the information of the rotational speed V _M of the shaft 6 is inputted.

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

In the above configuration, 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 in FIG.
It is to obtain the undetermined coefficient C _x of (b). That is, the tire 1 and 3 in the diagonal indicated by the continuous lines in FIGS. 1, a set of tire rotation speed F _n between the tire 2 and 4 in the diagonal lines indicated by the broken line after adding separately , 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 number F _n to obtain a deviation value D.

[0020] has a basic determination process that the abnormality detection of the tire air pressure by comparing the thus deviate width with a predetermined width, which will be described later with resulting deviation value D and D _S, the High-speed tire pressure abnormality judgment processing by comparison (reducing the number of processing steps in the control device)
In addition, the hardware configuration in the control device 11 can be minimized, thereby realizing a low cost.

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 to return the deviation value D to the initial state. Normally, at the start of driving of a vehicle, not all tires have 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 emergency tires with a small outside diameter, or when the vehicle speed is insufficient, all tires are not under the same conditions, The difference between the numbers cannot be accurately determined on the tire pressure warning device side. Therefore, before calculating the deviation value D, an undetermined coefficient _Cx is obtained and then F ₁ + F
By multiplying ₃ , the correction for tire replacement etc. after puncture repair is performed.

Therefore, when all the tires are normal, the undetermined coefficient C _x has a value close to “1” and does not significantly affect the deviation value D. However, for example, when the tire 1 is a emergency tire 9, while the "1" value less than the fact that F ₁ is increased, the air pressure of the other tires 2, 3 and 4 is abnormally low, undetermined values of the coefficients C _x to generate a warning (warning) as described below as a determination condition not met in the case of extremely deviates from "1".

Next, FIG. 3 is a flow chart schematically showing a state in which an abnormality in the tire air pressure is determined from the difference in the number of rotations of the tire. Each of the flow charts to be described later is appropriately interrupted with respect to the flow chart in FIG. It is configured as follows. In the figure, when the process is started, step S1
, The process start, tire rotation speed data, and the like are input as appropriate, and the flow advances to step S2 to determine whether the flag 1 is set. In this step S2,
When the flag 1 is set, the process proceeds to step S3 to determine whether or not the determination condition is satisfied by determining that the above-mentioned undetermined coefficient _Cx is not an abnormal value. When it is determined that the determination condition is satisfied, the process proceeds to step S4, and the tire air pressure is determined. On the other hand, if the flag 1 is not set in step S2, the process proceeds to step S5 and returns.

FIG. 4 is a flowchart for determining whether the determination condition is satisfied. More specifically, FIG. 4 shows an example of an operation for initializing the above-mentioned undetermined coefficient _CX and generating a warning after detecting an abnormality of the undetermined coefficient _CX. Is shown. In FIG. 4, when the process for determining the satisfaction of the determination condition is started, in step S11, the process start, tire rotation speed data and the like are appropriately input, the process proceeds to step S12, and the initial state in which the determination start switch SW is turned on. Is determined (when a manual switch is provided in the driver's seat). Alternatively, in step S10 surrounded by a broken line, after the deviation value D changes extremely, after the ignition switch is turned on,
Alternatively, after the diagnostic terminal of the self-diagnosis terminal is in the initial state, an initial state signal is automatically output to perform an initial state in which the determination condition is satisfied, 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 the tire pressure
While letting the driver know that preparations are complete,
A flag 0 is set to prohibit the judgment. Next,
Proceed to step S14 to determine the undetermined coefficient C _x Vehicle is constant to get
It is determined whether or not the vehicle is in the traveling state, and the undetermined coefficient C
_x When it is determined that can be obtained, step S15
The undetermined coefficient C is calculated according to the equation (b) of FIG._x Is calculated. Continued
In step S16, the obtained undetermined coefficient C_x Is "1"
It is difficult to judge whether it is an appropriate value that does not deviate greatly.
If the value is an appropriate value, the process proceeds to step S21,
Previous undecided coefficient C_x If is stored, this value
rewrite. If it is not stored, a new registration
Record. By executing the above steps, the undetermined coefficient C_x 
Is registered, and the deviation value D is calculated in consideration of the initial state.
It becomes possible. Therefore, the process proceeds to step S22, and the initial
Set the status switch to "zero" and set the warning lamp 1
0 is turned off and the air pressure judgment is started, while the main flow in FIG.
Set flag 1 in rocha-that.

On the other hand, in step S16, for example,
Immediately after only one tire has traveled on the large road depression, and the undetermined coefficient C _x is uncertain greatly deviating from “1”, it is determined in step S17 whether or not such an uncertain state exists. After that, step S1 is performed again.
4 and execute the following steps. In step S17, when it is determined that the undetermined coefficient C _x is not indefinite but largely deviates from “1” of the undetermined coefficient C _x and is an unsuitable value, the warning lamp 10 becomes noticeable because the tire pressure is abnormal. Flashes to alert the driver. Thereafter, 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, for example, even when an emergency tire is mounted or immediately after tire replacement, a tire pressure abnormality can be accurately determined from a difference in tire rotation speed, while immediately after starting operation. By evaluating the undetermined coefficient _Cx as described above, it is possible to easily inform the driver of the tire pressure abnormality, so that sufficient measures can be taken before entering the expressway, for example, and safety can be further secured. In the above, an example of the control flow until immediately after the start of driving has been described. Next, when the vehicle is running, the deviation D obtained from the above equation (the equation of FIG. 2A) has a predetermined width. A determination process for detecting an abnormality in tire air pressure by comparing with the deviation width D _S will be described.

[0028] (a) in FIG. 5, a deviation between the width D _S on the vertical axis,
FIG. 9 is a diagram showing a state in which a deviation value D is within a normal range, with time t on the horizontal axis. FIG. 5B is a diagram showing a state where the deviation value D is in an abnormal state. Then, (a) in FIG. 6 is a state deviation width D _S gradually increases in proportion to the vehicle speed A, also (b) in FIG. 6 by direct proportion to the deviation width D _S halfway the tire temperature rise B Temperature FIG. 10 is a diagram showing a state in which B ｀ is increased and is not changed thereafter.

First, in FIG. 5 (a), 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 the value is the opposite, Since it becomes negative, the deviation width D _{S in the} range (shown by a dashed line) between the positive D _S1 and the negative D _S1 in the figure becomes the tire pressure normal range, and the deviation value D obtained after the vehicle runs normally. As shown by the solid line and the dashed line in the figure, it is determined that the state is normal when the determination is made within the predetermined period T.

On the other hand, in FIG. 5B, the deviation value D deviates upward or downward within a predetermined period T within a range (shown by a dashed line) between the above-mentioned positive D _S1 and negative D _S1. If so, the tire pressure abnormality is determined. That is, in FIG. 5 (b), if the integrated value 範 囲 D of the range exceeding the positive value D _S1 of the deviation value D exceeds a predetermined value within a predetermined period T, it is determined that the tire pressure is abnormal, and the deviation value D
It is also determined that the tire air pressure is abnormal even if the positive _DS1 suddenly exceeds the negative _DS1 after exceeding the negative _DS1 .

Next, in each drawing of FIG. 5, the positive / negative deviation width D _S2 indicated by the broken line gradually increases in proportion to the increase of the vehicle speed A, as shown in FIG. Like that. Thus by varying the deviation width D _S in accordance with the vehicle speed A, thereby eliminating negative effects due to securing the deviation width D _S. That is, as the vehicle speed A increases, the deviation value D tends to increase, and the damage at the time of occurrence of puncture increases. Therefore, the deviation width D _S2 is set to be larger than the deviation width D _S1. Try to make it less.

Also, as shown in FIG. 6B, by gradually increasing the temperature to the temperature B ｀ in direct proportion to the tire temperature rise B, and setting the deviation width D _S2 so as not to change thereafter.
It is possible to make a determination in consideration of a rise in tire air pressure due to a rise in temperature. Here, parameters other than the vehicle speed A and the tire temperature B shown in FIG. 6 include a load determined by the number of occupants and the like, a value detected by a vehicle height sensor of the active suspension, and a degree of turning. There are yaw turning moment values to be detected, front and rear G, left and right G, and the like.

As described above, without fixing the deviation width D _S , by appropriately changing the deviation width D _S2 in consideration of various factors, it is possible to determine the tire air pressure according to the running state of the vehicle. Can be performed.

Next, FIG. 7 is a flowchart for determination based on the diagram shown in FIG. 5B. When the air pressure determination is started after detecting that there is no abnormality in the undetermined coefficient _CX , Proceeding to step S30, the determination timer is started,
Set "4" in the flag. Thereafter, the process proceeds to step S31, where the deviation value D obtained by the above-described expression is equal to the positive deviation width D.
If it is determined that the flag is larger than S, and if the flag is larger than _S, it is abnormal. Therefore, the process proceeds to step S32, and it is determined whether the flag is set to “2”. To set the integral value S _k to a value _obtained by adding 1 to the previous integral value S _{k -1} and then to step S
Proceed to 35 to set the flag to "2". Further, in step S32, if the flag 2 is not set, the flow proceeds to step S35 to set the integral value S _k to zero. In step S35, the process proceeds to step S41 to determine whether a predetermined time (cycle) T has elapsed.

On the other hand, in step S31, the deviation value D
There When it is determined that the positive deviation width D less than _S, is the subsequently deviation value D proceeds to step S36 of whether the negative deviation width D or _S is less than determination. In this step S36,
Although deviation D that is determined at the moment of least determination if it is determined that the negative deviation width D _S less is abnormal,
Since there may be a simple noise factor, the process proceeds to step S37 to wait for a sufficient time for determination to determine whether or not "3" is set in the flag. If "3" is set in the flag in step S37,
Proceeding to step S38, the integral value {S _{k is changed} to the previous integral value}
After setting to a value obtained by adding 1 to S _{k −1} , the process proceeds to step S41 and waits for the elapse of time T.

On the other hand, if it is determined in step S37 that "3" has not been set in the flag, step S39 is reached.
In "3" is set in the flag, followed by the integral value [sigma] s _k from being set to "zero" at step S40, waits for the lapse of time T the procedure proceeds to step S41. When the time T has elapsed, the process proceeds to step S42, while returning to step S31 until the time T has elapsed. In step S42, "4" is set in the flag, and the determination result based on the above-described series of steps is prepared.
Proceeds to 43, when the integral value S _k or the integral value [sigma] s _k is determined to exceed the predetermined value, the tire pressure abnormality is declared in step S44. If it is determined that the value is not more than the predetermined value, the process returns.

If it is determined in step S44 that the tire pressure is abnormal, the flow advances to step S45 to turn on a warning lamp, while in the case of a vehicle equipped with an ABS device, automatic control is performed so as to control the braking operation to a safe side. I do. Similarly, in the case of a vehicle equipped with a TRC device and a vehicle equipped with a 4WS device, the control is automatically performed so as to be on the safe side, and the control is continued until the tires return to a normal state.

By performing control as described above, in the case where the detection of the tire rotation speed is effectively used, it is possible to accurately determine an abnormality in the tire pressure by eliminating a noise factor.

Next, FIG. 8 is a flow chart of the puncture sensing, when the deviation value D is out larger than the deviation width D _S as indicated by a broken line in FIG. 5 (b), the tire Since the puncture state is caused by a sudden decrease in air pressure, the puncture determination is performed. In FIG. 8, when the process is started, in step S50,
Absolute value comparison is of the deviation value D and the deviation width D _S, if the deviation value D is larger than the absolute value of the deviation width D _S proceeds to step S52 waits for the lapse of time T the procedure proceeds to step S51. In this step S52, steps S50 and S51
If even after execution determination whether or not there is in the running predetermined U number of times, still the deviation value D is determined to be larger than the absolute value of the deviation width D _S is step S53
And a puncture determination is made. 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 to be controlled to the safe side. Similarly, in the case of a vehicle equipped with a TRC device and a vehicle equipped with a 4WS device, the control is automatically performed so as to be on the safe side, and the control is continued until the tires return to a normal state. By performing the puncture determination as described above, the puncture determination can be accurately performed by determining the air pressure abnormality occurring 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 whether the tire pressure is abnormal by turning on the warning lamp, and the driver has sufficient practicality. Is not specified, and it is more preferable that it can be specified. Therefore,
In order to identify a tire having an abnormal air pressure and to notify the driver of the abnormality, processing by a flowchart for identifying an abnormal tire in FIG. 9 is performed, and each warning lamp shown in FIG. 10 is displayed.

Therefore, the processing for identifying the abnormal tire is started.
Then, the process proceeds to step S60 in FIG.
, The deviation value D obtained by using the equation (a) in FIG.
Value and deviation width D_s Are compared, and F₁ + F_Three F than the value of
_Two + F_Four Is larger and the deviation value D is a negative deviation width D_s Yo
If it is determined that the difference is greater than _Two 
+ F_Four Tire 2, 4 which shows the rotation of the tire
It is determined that a puncture has occurred due to an abnormality.

Subsequently, in step S65,
The rotation speed and the engine speed of the tire 4 driven through the differential device 8
Gin rotation speed V_M And the value of the final reduction ratio multiplied by the tire
Number of rotations F of 4_Four Is performed, and the rotation speed F of the tire 4 is
_Four Is the engine speed V _M If greater than tie
In step S67, it is determined that the yam 4 is in a punctured state.
After making a determination, the process proceeds to step S68. This step S68
Now, the display as shown in FIG.
Tire 4 is in a punctured state for a bad driver
To inform. On the other hand, in step S65, the tire 4
Of rotation F_Four Is the engine speed V_M Smaller place
In step S6, it is determined that the tire 2 is in a punctured state.
7 and proceed to step S68 to display similarly
I do.

In step S60, the deviation value D
Value and deviation width D_s Are compared, and F ₁ + F_Three Than the value of
F_Two + F_Four Is smaller, and the deviation value D is a negative deviation width D._s 
If it is determined that it is greater than
Difference value D and positive deviation width D_s And the deviation value D is positive
Difference width D_s If it is determined that it is larger than
Go ahead, F₁ + F_Three One of tires 1 and 3 showing rotation
Judge that there is a puncture due to an abnormality in one of the tires
You. On the other hand, in step S61, the deviation value D
Width D_s If the difference is smaller than
Because there is, the process proceeds to step S62 and the system failure
Is output and the flag is set to “X” to return to the normal flow.
Attribute.

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 rotation speed F _{3 of the} tire ₃
Comparison is performed in the case is greater than the engine speed V _M towards the rotational speed F ₃ of the tire 3 is determined in step S67 that the tire 3 is in a punctured state, the process proceeds to step S68, with respect to the driver To inform that the tire 3 is in a punctured state. On the other hand, in step S66, the that tire 1 is in the puncture state when more speed F ₃ of the tire 3 the engine speed V _M and smaller than determined in step S67, the step S68
Proceed to and display similarly.

Next, FIG. 10A is an energization diagram of the first embodiment of the warning lamp display, FIG. 10B is a display example according to the second embodiment, and FIG. 10C is a display example according to the third embodiment. And (d) are schematic diagrams showing display examples according to the fourth embodiment. First, in FIG. 10A, the tire 1 or 3 punctured by the above-described flow chart in FIG.
Is specified, the warning lamp display is displayed once at predetermined time intervals as shown in the figure to notify the driver that the tire 1 is in a punctured state. When the tire 3 is punctured, three times are displayed at predetermined time intervals,
Notify puncture status. Thereafter, similarly, two or four flashes are performed to notify the punctured tire. With such a display method, a punctured tire can be displayed by providing only one warning lamp 10 used as described above in the flowchart of FIG.

FIG. 10B shows an example in which a punctured tire is displayed using a so-called 7-segment display. 10 (c) shows the tire 1 as F
L, tire 2 FR, tire 3 RR, tire 4 RL
This is an example in which a punctured tire is directly displayed by printing and displaying on a display panel, and arranging lamps on the back surface of the display panel. FIG. 10 (d) shows an example in which pictographs are printed and displayed, lamps are provided on the back of the display panel, and punctured tires are directly displayed.

By specifying and displaying a punctured tire as described above, for example, when a puncture occurs, it is not necessary to go outside 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 in order to detect a difference in tire rotation speed. However, the present invention is not limited to this. There is a method of judging from the distance and the like, which can be appropriately selected.

[0049]

As described above, according to the present invention, when the difference in the number of rotations of the tire is determined by the tire pressure warning device in order to constitute the tire pressure warning device, the optimum value is determined according to the running state of the vehicle. Tire pressure determination can be accurately performed.

[Brief description of the drawings]

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

Figure 2 is a diagram showing an equation for determining the deviation value and undetermined coefficients, is a diagram illustrating the drawing, the equation for (b) are undetermined coefficients C _X indicating the equation for (a) the deviation value D .

FIG. 3 is a flowchart schematically showing a state in which a tire air pressure abnormality is determined from a difference in tire rotation speed.

FIG. 4 is a flowchart for determining whether a tire pressure determination condition is satisfied.

[5] is a comparison view 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 time t on the horizontal axis, showing that the deviation value D is within a normal range, and (b) is a diagram showing that the deviation value D is in an abnormal state. FIG.

6 is a corresponding view of the deviation width D _S and the vehicle state,
(A) is a state deviation width D _S gradually increases in proportion to the vehicle speed A, also (b) in FIG. 6 increases the deviation width D _S to `temperature B by direct proportion halfway to the tire temperature rise B It is a figure showing a state that is not changed thereafter.

FIG. 7 is a determination flowchart 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.

10A and 10B show an embodiment of an alarm device, wherein FIG. 10A is an energization diagram of a first embodiment in which a warning lamp is displayed, and FIG.
FIG. 14 is a schematic diagram illustrating a display example according to an embodiment, (c) is a schematic diagram illustrating a display example according to a third embodiment, and (d) is a schematic diagram illustrating a display example according to a 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.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-6-286428 (JP, A) JP-A-59-206212 (JP, A) JP-A-6-92118 (JP, A) JP-A-5-206118 213019 (JP, A) JP-A-6-166308 (JP, A) JP-A-63-305011 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60C 23/00-23 / 08

Claims (2)

(57) [Claims] 1. A determines abnormality of tire air pressure by using a detection signal of a wheel speed sensor for detecting individually a rotational state of each tire of the vehicle, a tire pressure warning device for outputting an alarm, rotation between the tire By comparing a deviation value based on a value related to the difference with a deviation width having a predetermined upper limit value and a lower limit value, a determination unit that determines the tire pressure abnormality, a vehicle speed detection unit that detects a vehicle speed, and the vehicle speed detection unit. as the detected vehicle speed is more unlikely to be determined to abnormal air pressure greater, and and a predetermined value changing means for changing the upper limit value and the lower limit value, the predetermined value change means, said deviation as the vehicle speed increases
The upper limit is increased so that the width is increased, and the lower limit is increased.
A tire pressure warning device, wherein the pressure is corrected to be smaller . 2. A determines the tire air pressure abnormality by using a detection signal by the wheel speed sensor for detecting individually a rotational state of each tire of the vehicle, a tire pressure warning device for outputting an alarm, rotation between the tire By comparing the deviation value based on the difference value with a deviation width having predetermined upper and lower limits, a determination unit that determines the tire pressure abnormality, and the deviation width, when the tire temperature is lower than a predetermined temperature, A tire pressure alarm device comprising: a predetermined value changing means for setting a value to be increased with an increase in tire temperature.