JPH11295190A - Warning device for vehicular tire inflation pressure drop - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely detect and warn of vehicular tire inflation pressure drop in a simple structure. SOLUTION: A traveling distance of a vehicle in a set time based on a navigation information is found by an alarm control part 17, and traveling distances of respective wheels in a set time in a tire effective radius r0 based on wheel speeds from wheel speed sensors 19fr, 19fl, 19rr, 19rl and found. Tire inflation pressure of each wheel is detected from the traveling distance based on the navigation information and the traveling distances of respective wheels, and the warn of tire inflation pressure drop is output via a warning device 20 when the detected tire pressure pressure is lower than a preset threshold value.

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 for a vehicle which detects a decrease in tire pressure during running and issues a warning.

[0002]

2. Description of the Related Art Conventionally, various technologies have been developed for an alarm device that detects a decrease in tire air pressure during running and issues an alarm. For example, Japanese Utility Model Publication No. 2-31281 discloses that a tire air pressure sensor having a permanent magnet which operates so as to approach and close to a magnetically sensitive switch when the air pressure in the tire is reduced is provided on a rim, and the magnetic field of the permanent magnet is magnetically sensitive. A tire pressure warning device that detects a decrease in tire air pressure by detecting with a switch and issues an alarm is disclosed.

[0003] However, the tire air pressure warning device described in Japanese Utility Model Publication No. 2-31281 directly detects a decrease in tire air pressure. Need to be processed,
In addition, since it is necessary to provide a sensor directly on each wheel, the structure of the entire apparatus becomes complicated, which leads to an increase in cost.

[0004] In response to this, a number of alarm devices have been developed which are provided with means for indirectly detecting a decrease in tire air pressure. For example, wheel speed pulses from tires at diagonal front, rear, left and right have been multiplied. It is provided with a so-called tire load radius detecting type air pressure drop detecting means for detecting a decrease in tire air pressure based on the ratio, or with a so-called tire resonance point detecting type air pressure drop detecting means for estimating the air pressure from unsprung vibration. There are things.

However, the above-described tire load radius detection method can detect only a relative decrease in the air pressure of each tire. Therefore, if the air pressures of all the tires decrease simultaneously, it is not possible to detect the decrease in the air pressure. Have difficulty. Further, it is difficult for the above-described means of the tire resonance point detection method to detect a decrease in air pressure during traveling at an extremely low speed and traveling at a high speed.

[0006]

As described above, in each of the above-mentioned prior arts, the air pressure drop detecting means is constituted by a simple structure, and it is possible to reliably detect the absolute decrease in air pressure regardless of the running state. It was difficult.

The present invention has been made in view of the above circumstances, and reliably detects a decrease in tire air pressure with a simple structure.
It is an object of the present invention to provide a vehicle tire pressure drop warning device capable of giving a warning.

[0008]

In order to solve the above-mentioned problems, a vehicle tire pressure drop warning device according to the first aspect of the present invention receives a radio wave from a global positioning satellite system and measures the vehicle's own position. A navigation device having a function of performing the following, and a wheel speed detecting means for detecting a wheel speed of the vehicle, wherein a travel distance of the vehicle at a set time is calculated based on own vehicle position information measured by the navigation device. In addition, based on the wheel speed information detected by the wheel speed detection means, calculates the travel distance of the vehicle at the set time at the preset reference tire effective radius, and calculates the travel distance of the vehicle and the wheel based on the vehicle position information. The tire pressure is detected by comparing the travel distance of the vehicle based on the speed information, and an alarm is issued when the detected tire pressure is equal to or less than a preset value. And alarm control means for outputting the item, is characterized in that a warning means for warning that the tire pressure has dropped in response to the alarm signal from the alarm control unit.

In other words, the alarm device for alarming decrease in tire air pressure of a vehicle according to the first aspect of the present invention comprises:
While calculating the travel distance of the vehicle at a set time based on the vehicle position information measured by the navigation device,
The running distance of the vehicle at the set time at the preset reference tire effective radius based on the wheel speed information detected by the wheel speed detecting means is calculated, and the running distance of the vehicle based on the own vehicle position information and the wheel speed information are calculated. The tire pressure is detected by comparing the travel distance of the vehicle based on the tire pressure, and when the detected tire pressure is equal to or less than a preset set value, an alarm signal is output, and the alarm means outputs an alarm from the alarm control means. It warns that the tire pressure has dropped in response to the signal.

According to a second aspect of the present invention, in the vehicle tire pressure drop warning device according to the first aspect, the wheel speed detecting means detects a wheel speed of each wheel of the vehicle. It is characterized by being.

That is, according to a second aspect of the present invention, in the vehicle tire pressure drop warning apparatus according to the first aspect, the wheel speed detecting means detects a wheel speed of each wheel of the vehicle. The tire control for each wheel can be detected by the alarm control means.

According to a third aspect of the present invention, there is provided a vehicle tire pressure drop warning device according to the first or second invention, wherein the warning control means is configured to control a travel distance of the vehicle based on the vehicle position information. And, from the difference between the travel distance of the vehicle based on the vehicle position information and the travel distance of the vehicle based on the wheel speed information, calculate the actual effective tire radius of the wheels,
The tire pressure is detected based on the calculated tire effective radius.

According to a fourth aspect of the present invention, there is provided a vehicle tire pressure drop warning device according to the first or second invention, wherein the warning control means is configured to control a travel distance of the vehicle based on the vehicle position information. And a difference between the traveling distance of the vehicle based on the wheel speed information and a correction coefficient of the reference tire effective radius for matching the traveling distance of the vehicle based on the wheel speed information with the traveling distance of the vehicle based on the own vehicle position. The tire pressure is calculated based on the calculated correction coefficient of the reference tire effective radius.

According to a fifth aspect of the present invention, in the vehicle tire pressure drop warning device according to the first to fourth aspects, the warning control means is configured to perform the setting based on an input from the navigation device. It is characterized in that it is checked whether or not a curve exists in the traveling route at the time, and when a curve exists in the traveling route, the tire pressure is corrected according to the curve.

That is, the tire pressure drop warning device for a vehicle according to the invention described in claim 5 is described in claims 1 to 4.
In the invention described in the description, the alarm control unit checks whether or not a curve exists on the traveling route at the set time based on an input from the navigation device. By correcting the tire pressure according to the above, the detection accuracy of the tire pressure is improved.

According to a sixth aspect of the present invention, there is provided an apparatus for alarming decrease in tire air pressure of a vehicle according to the first to fifth aspects, further comprising an acceleration detecting means for detecting an acceleration of the vehicle. It is characterized in that it is checked whether or not the vehicle has accelerated based on an input from the acceleration detecting means, and if there has been accelerated traveling, the tire pressure is corrected according to the acceleration.

That is, the alarm device for alarming decrease in tire air pressure of a vehicle according to the invention of claim 6 is described in claims 1 to 5.
In the invention described above, the vehicle further includes acceleration detection means for detecting acceleration of the vehicle, wherein the alarm control means checks whether or not the vehicle has accelerated based on an input from the acceleration detection means. By correcting the tire pressure according to the acceleration, the detection accuracy of the tire pressure is improved.

According to a seventh aspect of the present invention, there is provided an apparatus for alarming decrease in tire air pressure of a vehicle according to the first to sixth aspects, further comprising an atmospheric pressure detecting means for detecting an atmospheric pressure. And detecting the amount of air in the tire based on the detected tire pressure and atmospheric pressure.

That is, according to the seventh aspect of the present invention, there is provided an alarm device for a decrease in tire air pressure of a vehicle.
In the invention described above, an atmospheric pressure detecting unit that detects an atmospheric pressure is provided, and the alarm control unit detects the amount of air in the tire based on the detected tire air pressure and the atmospheric pressure, thereby specifically reducing the tire air pressure. Recognize the cause.

According to the present invention, there is provided an alarm device for detecting a decrease in tire air pressure of a vehicle according to any one of claims 1 to 7, further comprising an outside air temperature detecting means for detecting an outside air temperature. And detecting the amount of air in the tire based on the detected tire pressure and the outside air temperature.

That is, the tire pressure drop warning device for a vehicle according to the invention described in claim 8 is claimed in claims 1 to 7.
In the invention described in the above, an outside air temperature detecting unit for detecting an outside air temperature is provided, and the alarm control unit detects the amount of air in the tire based on the detected tire air pressure and the outside air temperature. Recognize the cause.

According to a ninth aspect of the present invention, there is provided the vehicle tire pressure drop warning device according to any one of the first to eighth aspects, wherein the warning means is adapted to provide a warning when the tire pressure drop is warned. It is characterized by displaying the nearest facility where tire replacement or tire pressure adjustment is possible based on input from the device.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 relate to a first embodiment of the present invention, FIG. 1 is a schematic configuration diagram of a tire pressure drop warning device as a whole, FIG. 2 is a functional block diagram of a navigation device, and FIG. It is a flowchart of a routine.

In FIG. 1, reference numeral 1 denotes an engine disposed in the front part of the vehicle.
An automatic transmission (including a torque converter and the like) 2 behind the engine 1 to a transmission output shaft 2a
Is transmitted to the center differential device 3 through
From the center differential device 3, a rear drive shaft 4, a propeller shaft 5, and a drive pinion 6 are input to a rear wheel final reduction device 7, while the center differential device 3 is input to a front wheel end reduction device via a front drive shaft 8. The data is input to the reduction gear 9.

The driving force input to the rear wheel final reduction gear 7 is transmitted to the left rear wheel 11rl via the rear wheel left drive shaft 10rl and to the right rear wheel 11rr via the rear wheel right drive shaft 10rr. The driving force input to the front wheel final reduction gear 9 is transmitted to the left front wheel 11fl via the front left drive shaft 10fl and to the right front wheel 11fr via the front right drive shaft 10fr.

Reference numeral 17 in the figure indicates a tire pressure detected based on the running state of the vehicle, and when the detected air pressure falls below a preset value, an alarm control is performed through an alarm device 20 as alarm means. The alarm control unit 17 is an alarm control unit. The alarm control unit 17 receives data regarding the vehicle position (latitude, longitude, altitude, and the like) detected by the navigation device 18 and road information.
Wheel speed sensors 19fr, 19f as wheel speed detecting means
1, 19rr, each wheel 11fr detected at 19rl,
Wheel speed information of 1fl, 11rr, and 11rl is input.

The alarm controller 17 includes an atmospheric pressure sensor 13 as atmospheric pressure detecting means, an outside air temperature sensor 14 as outside air temperature detecting means, a vehicle speed sensor 15 as acceleration detecting means, a throttle opening sensor 16 and the like. The data on the atmospheric pressure, outside air temperature, vehicle speed, throttle opening, etc. detected by the engine (E / G) / transmission (T /
M) The data is input via the control unit 12.
That is, the alarm control section 17 receives the data used for controlling the engine 1 and the automatic transmission 2 from the E / G / T / M control section 12 via the bus line. ing. Here, the vehicle speed sensor 15 is provided, for example, on the transmission output shaft 2a, and detects the vehicle speed by detecting the rotation speed of the transmission output shaft 2a.

As shown in FIG. 2, the navigation device 18 is a general one, for example, a vehicle position detection sensor unit 18a, an auxiliary storage unit 18b, and an information display unit 18.
c, an operation unit 18d, and a calculation unit 18e.

The vehicle position detecting sensor section 18a is, specifically, a global positioning satellite system (Global Positioning Satellite System).
ng System (GPS), which is connected to a GPS receiver for measuring the position of the vehicle by receiving radio waves from GPS satellites, a geomagnetic sensor for detecting the absolute running direction of the vehicle, and other driving information related to the vehicle position. Are collected.

The auxiliary storage device 18b is, for example, a CD-ROM.
It is constituted by a ROM device and is formed in a read-only storage device in which a CD-ROM in which road map information including road information and topographical information is recorded is set. The above CD-RO
M stores road map information, and further stores information such as road type information such as expressways, general national roads, and local roads, and traffic conditions related to intersections.

The information display section 18c is formed of a liquid crystal display for displaying a map, the position of the vehicle (latitude / longitude / altitude), azimuth, the position of the vehicle on the map, the optimum route to the destination, and the like. A touch panel as the operation unit 18d is connected integrally with the information display unit 18c (liquid crystal display) to change the scale of the map, display the details of the place names,
An operation input for switching the display such as the regional information and the route guidance can be performed.

The arithmetic section 18e combines the traveling information of the vehicle obtained from the vehicle position detecting sensor section 18a with the map information read from the auxiliary storage device 18b while performing arithmetic operations such as map matching, and the like. The result is sent to the information display unit 18c based on the operation signal sent from the operation unit 18d, and the current position of the vehicle, a map around the vehicle, the optimal route to the destination, and the like are displayed.

The alarm device 20 includes a chime buzzer,
It is configured by an audio alarm, a warning light, or the like, or a combination thereof. Based on an alarm signal from the alarm control unit 17, an alarm is issued to notify the driver that the tire pressure of the wheel has decreased. Has become.

Here, the alarm device 20 may be replaced by the information display section 18c of the navigation device 18. In this case, at the time of an alarm notifying a decrease in tire pressure, the nearest gas station, car supply store, car dealer, or the like is extracted from the map information stored in the auxiliary storage device 18b, and tire replacement, air addition, and the like are performed. Possible locations can be notified to the driver.

The alarm control unit 17 includes a CPU, a ROM,
It is configured to include a RAM and the like, and calculates the traveling distance of the vehicle for a set time from the own vehicle position information input from the navigation device 18 and the wheel speed sensors 19fr, 19f
From the wheel speed information input from 1, 19rr, 19rl, the respective wheels 11fr, 11fl, 11r for the set time are set.
The travel distance based on r and 11rl is calculated, and the tire pressure of each wheel is detected by comparing the travel distance based on the navigation information with the travel distance based on the wheel speed of each wheel. When the detected air pressure of the tire is equal to or lower than a preset pressure, an alarm is issued through the alarm device 20.

Hereinafter, specific alarm control by the alarm controller 17 will be described with reference to the alarm control routine of FIG. In this routine, first, in step (hereinafter abbreviated as "S") 101, navigation information (vehicle position information such as latitude, longitude, and altitude, and information indicating a road shape) is input from the navigation device 18, and From the wheel speed sensors 11fr, 11fl, 11rr, 11rl, the wheel speed of each wheel, the atmospheric pressure sensor 13 to the atmospheric pressure, the outside temperature sensor 14 to the outside temperature, the vehicle speed sensor 15 to the vehicle speed, the throttle opening sensor 16 to the throttle opening, etc. The information is input, and the process proceeds to S102.

In step S102, the navigation information and the sensor information in step S101 are input in a predetermined calculation cycle, and it is determined whether the navigation information and the sensor information have been input for a preset time. If the input has not been performed in the predetermined operation cycle, the process proceeds to S103. If the input has not been performed in the predetermined operation cycle, the process returns to S101.

In step S103, the vehicle position information (latitude, longitude, and altitude on three-dimensional coordinates measured using a GPS satellite) input from the navigation device 18 is integrated, and the set time (predetermined calculation cycle) is calculated. After calculating the traveling distance L (n) of the vehicle in ()), the process proceeds to S104.

In S104, the wheel speed sensor 19
Based on the wheel speed information input from fr, 19fl, 19rr, 19rl, the set time (predetermined calculation cycle)
Distance L (fr), L (fl), L
After calculating (rr) and L (rl), the process proceeds to S105.
Here, the alarm control unit 17 previously measures and stores the reference tire effective radius r0 (the effective radius of the tire when the vehicle travels with the optimum air pressure applied to the tire).
At 104, based on the reference tire effective radius r0 and the wheel speed information from the wheel speed sensors 19fr, 19fl, 19rr, 19rl, the traveling distances L (fr), L (fl), L (rr) of the respective wheels at a set time. ) And L (rl).

In S105, the navigation device 1
From the road shape information input from 8, it is checked whether or not the traveling route on which the vehicle has traveled at the set time has a curve with a curvature greater than a preset curvature. The process proceeds to S106. On the other hand, if there is a curve having a curvature equal to or greater than the set curvature on the traveling route, the process proceeds to S107.

If it is determined in step S105 that there is no curve having a curvature equal to or greater than the set curvature on the traveling route, and the process proceeds to step S106, the process proceeds to step S1.
In 06, the traveling distance L based on the navigation information
(N) and the traveling distances L (fr), L (f
l), L (rr), and L (rl) are compared with each other to determine the difference between the traveling distance based on the navigation information and the traveling distance by each wheel, ΔL (fr), ΔL (f).
l), ΔL (rr), and ΔL (rl) are obtained, and the process proceeds to S109, where the differences in the traveling distances ΔL (fr), ΔL (fl),
From ΔL (rr), ΔL (rl) and the travel distance L (n) based on the navigation information, the tire effective radius r (fr), r (fl), r (rr), r (rl) of each wheel.
, And then proceeds to S110.

That is, when the vehicle is traveling with the actual tire effective radius of each wheel being r0, the traveling distances L (fr), L (fl), L (rr), L (rl) by each wheel are obtained.
And the travel distance L (n) based on the navigation information are set so as to match. In S106, the travel distances L (fr), L (fl), L
When the values of (rr) and L (rl) are different from the traveling distance L (n) based on the navigation information, it can be understood that the tire effective radius has changed. Then, the above S109
Then, the difference of the traveling distances ΔL (fr), ΔL (fl),
The actual tire effective radii r (fr), r (fl), r (rr) of each wheel are calculated from ΔL (rr), ΔL (rl) and the travel distance L (n) based on the navigation information.
Find r (rl).

On the other hand, in S105, it is determined that there is a curve having a curvature equal to or greater than the set curvature in the traveling route, and the process proceeds to S107. Is corrected, and the process proceeds to S108.

That is, when a curve having a large curvature exists in the traveling route, the traveling distance of each wheel differs due to the influence of the difference in the inner wheels and the difference in the traveling radius of the inner and outer wheels. So S1
In 07, the traveling distance L based on the navigation information is determined according to the curvature of the curve of the traveling path, the traveling distance of the curve, and the like.
(N) is corrected, and the traveling distances L (nfr), L (nfl), L (n) based on the navigation information corresponding to each wheel.
rr) and L (nrl) are calculated. Here, the alarm control unit 17 has in advance a correction coefficient for performing correction based on the difference between the inner wheel difference and the difference between the inner and outer wheel running radii corresponding to each wheel according to the curvature of the curve, the traveling distance of the curve, and the like. It is obtained and stored by an experiment or the like, and in S107, correction is performed using this correction coefficient.

In S108, the traveling distances L (nfr), L (n) based on the navigation information corresponding to each wheel
fl), L (nrr), L (nrl), and the traveling distances L (fr), L (fl), L (rr), L (r)
1), the difference between the mileage based on the navigation information and the mileage by each wheel,
ΔL (fr), ΔL (fl), ΔL (rr), ΔL (r
1) is obtained, and the process proceeds to S109, where the difference ΔL in the traveling distance is obtained
(Fr), ΔL (fl), ΔL (rr), ΔL (rl)
And the traveling distance L (nf) based on the navigation information
r), L (nfl), L (nrr), L (nrl), and the effective tire radii r (fr), r (fl), r of each wheel.
After calculating (rr) and r (rl), the process proceeds to S110.

That is, the effective radius of the tire of each wheel is r0
When traveling, the traveling distances L (fr), L (fl), L (rr), L (rl) by each wheel are represented by:
Travel distances L (nfr), L (nfl), L (nrr), L (nr) based on navigation information corresponding to each wheel
1) are identical to each other, and the above S1
08, the traveling distances L (fr), L
The values of (fl), L (rr), and L (rl) are the travel distances L (nfr), L (nfl),
When L (nrr) and L (nrl) are different, it can be understood that the actual tire effective radius fluctuates. Therefore, in the above S109, the difference ΔL (f
r), ΔL (fl), ΔL (rr), ΔL (rl),
Travel distance L (nfr), L based on navigation information
(Nfl), L (nrr), L (nrl) and the actual tire effective radius r (fr), r (f
1), r (rr) and r (rl) are obtained.

In step S110, the acceleration or departure from the vehicle speed inputted from the vehicle speed sensor 15 and the throttle opening inputted from the throttle opening sensor 16 such that the vehicle deviates from the preset acceleration range within the set time. It is checked whether or not the vehicle has accelerated to perform deceleration. If the vehicle has performed the above-described acceleration traveling, the process proceeds to S111. If the vehicle has not performed the above-described acceleration traveling, the process proceeds to S112.

At S110, it is determined that the vehicle is accelerating, and the process proceeds to S111. At S111, the tire effective radius r (fr) of each wheel obtained at S109 is calculated.
After correcting r (fl), r (rr), and r (rl) according to the acceleration, the acceleration running time, and the like, the process proceeds to S112.

That is, the flatness of the tire increases during acceleration running as compared with normal running at constant speed. For this reason, the tire effective radius at the time of acceleration running becomes smaller than the tire effective radius at the time of constant speed running. Therefore, in S111, the tire effective radii r (fr), r (fl), r (rr), and r (rl) of each wheel are corrected in accordance with the acceleration, the accelerated traveling distance, and the like, so as to perform normal normal speed traveling. Corresponding tire effective radius r '
(Fr), r '(fl), r' (rr), r '(rl)
Is calculated. Here, the alarm control unit 17 stores a correction coefficient for correcting the tire effective radius according to, for example, an acceleration or an accelerating travel distance, obtained by an experiment or the like, and stores the correction coefficient in S111. Is corrected using.

At S112, the tire effective radii r (fr), r (fl), r (rr),
r (rl), or the tire effective radii r ′ (fr), r ′ (fl), r ′ (rr), corrected in S111.
From r '(rl), the tire pressure p (fr), p
After calculating (fl), p (rr) and p (rl), S1
Proceed to 13.

That is, the relationship between the tire effective radius of each wheel and the tire pressure during running at a constant speed is obtained and stored in advance in the alarm control unit 17 through experiments and the like.
At S112, the tire effective radii r (fr), r (fl), r (rr), r (rl),
Alternatively, the tire effective radius r ′ corrected in S111.
(Fr), r '(fl), r' (rr), r '(rl)
From the relationship between the effective tire radius of each wheel and the tire pressure, the tire pressures p (fr), p (f
1), p (rr) and p (rl) are obtained.

At S113, the atmospheric pressure input from the atmospheric pressure sensor 13, the outside air temperature input from the outside air temperature sensor 14, and the tire pressures p (fr), p (fl) of each wheel calculated at S112. , P (rr), p (rl)
After calculating the absolute air amount in each tire from
Proceed to 14.

That is, the tire air pressure differs depending on the atmospheric pressure, the outside air temperature, and the like, even if the air amount in the tire is the same.
Therefore, in S113, the absolute air amount in the tire is checked using the atmospheric pressure and the outside air temperature input from the atmospheric pressure sensor 13 and the outside air temperature sensor 14, and the decrease in the tire air pressure is detected as the tire air amount. It is determined whether the change is due to a decrease in the atmospheric pressure or the atmospheric pressure or the outside air temperature. Here, in the alarm control unit 17, data indicating the relationship between the atmospheric pressure and the tire air pressure and the relationship between the outside air temperature and the tire air pressure in each tire air amount are obtained and stored in advance by experiments and the like. By using these data and the data input from the atmospheric pressure sensor 13 and the outside air temperature sensor 14, whether the decrease in the tire pressure is due to the decrease in the air amount in the tire, or
Recognize whether this is due to an increase in atmospheric pressure or a decrease in outside temperature.

In step S114, the tire pressures p (fr), p (fl), p (r) of each wheel obtained in step S112 are determined.
It is checked whether r) and p (rl) are smaller than a preset threshold value of the air pressure. If each tire air pressure is equal to or higher than the threshold value, it is determined that each tire air pressure is normal and navigation is performed. After the operation cycle of inputting the information and each sensor information is set to “0”, the process returns to S101.
If at least one of the tire pressures is smaller than the threshold value, the process proceeds to S115.

When it is determined in S114 that at least one of the tire pressures is smaller than the threshold value and the process proceeds to S115, in S115, an alarm is issued to alert the driver of a decrease in air pressure. Device 20
After outputting an alarm signal to the controller and setting the operation cycle of inputting the navigation information and each sensor information to “0”,
The process returns to S101.

At this time, the alarm device 20 determines whether the decrease in the tire pressure is due to a decrease in the air amount in the tire, or a temporary decrease due to a change in the atmospheric pressure, the outside temperature, or the like. The driver is informed of the information and the information such as the tire position where the air pressure drop has occurred. Further, the alarm device 20 is connected to the information display unit 18c of the navigation device 18.
In the case of substituting for a vehicle, the nearest gas station, car supply store, car dealer, or the like is extracted from the map information stored in the auxiliary storage device 18b, and a place where tire replacement or air addition can be performed is provided to the driver. Notify.

As described above, according to the first embodiment of the present invention, the travel distance for the set time based on the navigation information is determined, and the travel distance for the set time at the tire effective radius r0 is determined based on the wheel speed information. Then, since the tire pressure is detected from the difference between these traveling distances, it is possible to reliably detect a decrease in the tire pressure and issue an alarm.

Further, by correcting the traveling distance based on the navigation information according to the traveling state such as when traveling on a curve, the tire pressure can be corrected as a result, and the detection accuracy of the tire pressure can be improved. be able to.

Further, by correcting the tire effective radius in accordance with the running condition such as acceleration running, the tire pressure can be corrected as a result, and the detection accuracy of the tire pressure can be improved.

Further, since the air amount in the tire can be obtained based on the atmospheric pressure and the outside air temperature, whether the cause of the decrease in the tire air pressure is due to the decrease in the air pressure in the tire, or
It can be specified whether the change is due to a change in the atmospheric pressure, the outside temperature, or the like.

Further, since addition of a sensor or special processing is not required for the wheel or the tire for detecting the tire air pressure, the conventional wheel or tire can be used as it is and can be easily applied to various types of vehicles. .

Further, the nearest gas station, car supply store, car dealer, or the like is extracted from the map information of the navigation device 20, and the location where tire replacement, air addition, or the like can be performed is notified, so that the tire pressure can be promptly provided to the driver. Adjustment can be encouraged.

In the above S114, the threshold value of the air pressure is made variable according to the air amount in the tire, so that no alarm is issued when the decrease in the tire air pressure is caused by the atmospheric pressure, the outside air temperature or the like. It is also possible to do so.

In this embodiment, the wheel speed sensor 1
The wheel speed of each wheel is detected using 9fr, 19fl, 19rr, and 19rl to detect a decrease in each tire air pressure. However, the present embodiment is not limited to this.
5 is substituted for the wheel speed detecting means, and the average value of the wheel speeds of all the wheels is obtained from the vehicle speed information from the vehicle speed sensor 15;
A decrease in tire pressure may be detected from the travel distance based on the average value of the wheel speeds and the travel distance based on the navigation information. According to this method, it is possible to detect that at least one of the four wheels has reduced the tire air pressure.

Next, FIG. 4 relates to a second embodiment of the present invention, and FIG. 4 is a flowchart of a tire pressure drop warning routine. Note that the overall configuration of the tire pressure drop warning device according to the present embodiment is the same as that of the above-described first embodiment, and a description thereof will be omitted.

Here, in the above-described first embodiment, the tire effective radius of each wheel is obtained from the travel distance based on the navigation information and the travel distance of each wheel to detect a decrease in tire air pressure. In this embodiment, the correction coefficients C (fr), C (fl), C (rr), and C (rl) of each tire with respect to the reference tire effective radius r0 are obtained from the travel distance based on the navigation information and the travel distance of each wheel.
The difference is that a decrease in tire air pressure is detected in order to determine the tire pressure.

Hereinafter, specific alarm control by the alarm controller 17 will be described with reference to the alarm control routine of FIG. In the routine of the present embodiment, S201 to S20
No. 8 to S101 to S101 according to the above-described first embodiment.
The operation is the same as the operation up to 108, and the description is omitted.

In step S206 or S208, the difference ΔL between the traveling distance based on the navigation information and the traveling distance of each wheel.
(Fr), ΔL (fl), ΔL (rr), ΔL (rl)
Proceeding to S209, in S209, the difference ΔL (f between the traveling distance based on the navigation information and the traveling distance is calculated.
r), ΔL (fl), ΔL (rr), ΔL (rl), a correction coefficient C (fr) of the reference tire effective radius r0 for matching the traveling distance of each wheel with the traveling distance based on the navigation information, C (fl), C (rr), C (r
1), and the process proceeds to S201.

In step S210, it is determined whether or not the vehicle has accelerated at a predetermined acceleration or more within the set time based on the vehicle speed input from the vehicle speed sensor 15 and the throttle opening input from the throttle opening sensor 16. The process proceeds to S211 if the vehicle has performed the acceleration traveling, and proceeds to S21 if the vehicle has not performed the acceleration traveling.
Proceed to 2.

In step S211, the correction coefficients C (fr), C (fl), and C (r) of the respective wheels obtained in step S209 are obtained.
After correcting r) and C (rl) according to the acceleration and the acceleration traveling time, the process proceeds to S212. Here, the alarm control unit 17 stores the correction coefficients C (fr), C (fl), C (rr), and C (r) for each wheel according to the acceleration, the accelerated traveling distance, and the like.
A correction coefficient for correcting 1) is obtained and stored in advance by an experiment or the like, and in S211 the correction coefficient of each wheel is corrected using this correction coefficient to obtain C ′ (fr), C ′.
(Fl), C ′ (rr) and C ′ (rl) are obtained.

In step S212, the correction coefficients C (fr) and C (f) of the reference tire effective radius r0 obtained in step S209 are determined.
1), C (rr), C (rl), or S211
Correction coefficient C '(f
r), C ′ (fl), C ′ (rr), C ′ (rl), and tire pressures p (fr), p (fl), p (r
After calculating r) and p (rl), the process proceeds to S213. Here, the relationship between the correction coefficient of the reference tire effective radius r0 of each wheel and the tire air pressure is previously obtained and stored in the alarm control unit 17 through experiments or the like.

The control in steps S213 to S215 is the same as that in steps S113 to S115 in the first embodiment, and a description thereof will be omitted.

In the second embodiment, the same effects as those in the first embodiment can be obtained.

In the first embodiment and the second embodiment,
In the embodiment, the information such as the atmospheric pressure, the outside air temperature, the vehicle speed, the throttle opening and the like used for the engine control and the control of the transmission are also used as they are, thereby simplifying the apparatus without adding a sensor or the like. Although a sensor directly connected to the alarm device can be used, and the control unit of the engine transmission, the alarm control unit, the alarm device, and the navigation device are shown as being independent from each other. Various combinations having the same functions can be combined and combined into a single control device or a plurality of control devices without departing from the spirit of the invention.

[0075]

As described above, according to the present invention,
The vehicle travel distance based on the navigation information and the vehicle travel distance based on the wheel speed are obtained, and the tire pressure is calculated by comparing these. Therefore, it is possible to reliably detect a decrease in tire pressure with a simple structure and issue an alarm. Can be.

Further, since the value of the tire air pressure is corrected according to the curve running or the acceleration running, the detection accuracy of the tire air pressure can be improved.

Further, by detecting the amount of air in the tire using the atmospheric pressure and the outside air temperature, it is possible to recognize the specific cause of the decrease in the tire pressure.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an entire tire pressure drop warning device according to a first embodiment of the present invention.

FIG. 2 is a functional block diagram of the navigation device.

FIG. 3 is a flowchart of a tire pressure drop warning routine according to the first embodiment;

FIG. 4 is a flowchart of a tire pressure drop warning routine according to a second embodiment of the present invention;

[Explanation of symbols]

13 ... Atmospheric pressure sensor (atmospheric pressure detecting means) 14 ... Outside air temperature sensor (outside air temperature detecting means) 15 ... Vehicle speed sensor (acceleration detecting means) 16 ... Throttle opening degree sensor (acceleration detecting means) 17 ... Alarm control unit (alarm control) Means) 18 Navigation device 19fr, 19fl, 19rr, 19rl Wheel speed sensor (wheel speed detecting means) 20 Alarm device (warning device)

Claims (9)

[Claims] 1. A vehicle comprising: a navigation device having a function of receiving a radio wave from the global positioning satellite system to measure a vehicle's own position; and wheel speed detecting means for detecting a wheel speed of the vehicle. Calculating the traveling distance of the vehicle at the set time based on the vehicle position information measured by the navigation device,
Based on the wheel speed information detected by the wheel speed detecting means, the traveling distance of the vehicle at the set time at the preset reference tire effective radius is calculated, and the traveling distance of the vehicle and the wheel speed information based on the own vehicle position information are calculated. Alarm control means for detecting a tire pressure by comparing the travel distance of the vehicle based on the tire pressure, and outputting a warning signal when the detected tire pressure is equal to or less than a preset set value; and an alarm signal from the warning control means. Alarm means for alarming that the tire air pressure has dropped according to the following. 2. The apparatus according to claim 1, wherein said wheel speed detecting means is a wheel speed sensor for detecting a wheel speed of each wheel of the vehicle. 3. The vehicle control system according to claim 2, wherein the warning control means calculates a travel distance of the vehicle based on the vehicle position information and a difference between the vehicle travel distance based on the vehicle position information and the vehicle travel distance based on the wheel speed information. 3. The warning apparatus for tire pressure drop of a vehicle according to claim 1, wherein an actual tire effective radius of the wheel is calculated, and the tire pressure is detected based on the calculated tire effective radius. 4. The vehicle control system according to claim 1, wherein the warning control means determines a travel distance of the vehicle based on the wheel speed information from a difference between the travel distance of the vehicle based on the vehicle position information and the travel distance of the vehicle based on the wheel speed information. Calculate a correction coefficient of the reference tire effective radius to match the traveling distance of the vehicle based on the own vehicle position,
3. The apparatus according to claim 1, wherein the tire pressure is detected based on the calculated reference tire effective radius correction coefficient. 5. The alarm control means checks whether or not a curve exists on the traveling route at the set time based on an input from the navigation device. 5. The warning apparatus for tire pressure decrease of a vehicle according to claim 1, wherein the tire pressure is corrected according to the following. 6. An acceleration detecting means for detecting acceleration of the vehicle, wherein the alarm control means checks whether or not the vehicle has accelerated based on an input from the acceleration detecting means. 6. The warning device for tire pressure decrease of a vehicle according to claim 1, wherein the tire pressure is corrected according to the acceleration. 7. An apparatus according to claim 1, further comprising an atmospheric pressure detecting means for detecting an atmospheric pressure, wherein said alarm control means detects an air amount in the tire based on the detected tire air pressure and the atmospheric pressure. Item 7. A warning device for a decrease in tire air pressure of a vehicle according to Item 6. 8. An outside air temperature detecting means for detecting an outside air temperature, wherein the alarm control means detects an air amount in the tire based on the detected tire air pressure and the outside air temperature. Item 7. A tire pressure drop warning device according to Item 7. 9. The system according to claim 1, wherein the warning means displays a nearest facility where tire replacement or tire pressure adjustment is possible based on an input from the navigation device when warning of a decrease in tire pressure. 9. The warning device for a tire pressure drop of a vehicle according to claim 1.