JPH08156538A - Tire inflation pressure detecting device for vehicle - Google Patents

Abstract

PURPOSE: To enhance the precision of tire inflation pressure detection by judging that a vehicle is in a prescribed traveling state when the vehicle acceleration and deceleration detected values are within a prescribed time and a prescribed range, and detecting the tire inflation pressure at that time. CONSTITUTION: An arithmetic processing device 30c reads rotating angle speed detected values from wheel speed sensors 21FL-21RR every prescribed time, and performs the judgment whether the traveling state of the vehicle is in natural decelerating state or not, and the detection of the wheel whose pneumatic pressure is reduced lower than a prescribed value on the basis of these detected values. Namely, the wheel acceleration and deceleration detected value obtained from the rotating angle speed detected value is within a prescribed time and a prescribed range showing a prescribed traveling state of the vehicle, the vehicle is judged to be in the prescribed traveling state, and the tire inflation pressure of the wheel to be detected is detected at that time. Thus, the prescribed vehicle traveling state forming a premise of tire inflation pressure detection is precisely judged, and precision of tire inflation pressure detection can be enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting a tire pressure during running of a vehicle, and more particularly to a device for detecting a tire pressure based on a rolling radius and rolling resistance of a wheel. The present invention relates to a vehicle in which the running condition of the vehicle is accurately determined and the accuracy of tire pressure detection can be improved.

[0002]

2. Description of the Related Art As a conventional example of a device for detecting a tire pressure during running of a vehicle, based on a rolling radius of a wheel which fluctuates due to a change in tire pressure, an average value of reference wheels or four wheels and a target wheel are compared. Many devices for determining the tire air pressure state of the target wheel by comparison have been proposed in Japanese Utility Model Laid-Open No. 1-73002. In such a device, the tire pressure drop is detected by comparing the wheel speeds that increase as the rolling radius decreases.

Further, in such a device, when the variation of the rolling radius is caused only by the variation of the tire air pressure, the tire air pressure state is detected in order to detect the tire air pressure state based on the rolling radius. It is necessary to set the condition of the vehicle running state which is a prerequisite for detection, and various sensors for detecting the vehicle running state are installed. In order to eliminate the influence of the cornering resistance during turning, a steering angle sensor that detects the steering angle of the steering wheel is provided, and the steering angle detection value is, for example, “0”. When the brake switch is not ON to remove the influence, a vehicle height sensor is installed at each wheel position to remove the influence of road surface input, and for example, the average value of vehicle height detection values from each vehicle height sensor. The execution of the tire air pressure state detection is limited when the deviation with respect to is less than a predetermined value.

[0004]

However, in such a conventional tire pressure detecting device for a vehicle, as described above, the vehicle traveling condition is set in order to set the condition of the vehicle traveling condition which is a prerequisite for detecting the tire pressure condition. Since it is necessary to install various sensors for detecting the state, there is a problem that the cost is high. In addition, it is difficult to detect a state where a slight driving force is applied to the wheels by an existing sensor, and thus it is difficult to make a determination in a complete non-driving state. Further, the large number of sensors has a high possibility that the vehicle running state cannot be accurately determined due to sensor failure or the like.

The present invention has been made by paying attention to the problems of the prior art as described above, and is a premise of tire pressure detection in a device for detecting tire pressure based on the rolling radius and rolling resistance of a wheel. An object of the present invention is to provide a vehicle in which a predetermined vehicle traveling state is accurately determined, the accuracy of tire air pressure detection can be improved, and the cost of the device can be kept low.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, obtained the following knowledge and completed the present invention. In order to detect the tire air pressure based on the rolling radius and rolling resistance of the wheels, it is necessary to assume that the variation of the rolling radius and rolling resistance is caused by the variation of the tire air pressure. . That is, at least the wheel needs to be in a so-called free rolling state in which the force acting on the wheel is only rolling resistance and wheel load (to be exact, its reaction force). When the wheels are in such a free rolling state, the vehicle is in a so-called natural deceleration state, and the deceleration that occurs in the vehicle at this time is calculated in advance as a function of the vehicle speed by the vehicle specifications.

Therefore, it is considered that the running state of the vehicle can be determined from the wheel deceleration by comparing the calculated deceleration of the vehicle with the detected value of the wheel deceleration detected during traveling, for example. Also, the vehicle deceleration during natural deceleration is
Especially because it changes depending on the rolling resistance of the wheel and the wheel load,
Practically, it is necessary to set a predetermined range of the vehicle deceleration indicating a natural deceleration state, for example, in consideration of these expected fluctuations. By doing so, it is considered that it is possible to determine that the wheel is in the free rolling state, for example, when the wheel deceleration detection value is within the predetermined range for the predetermined time.

The vehicle tire pressure detecting device according to the present invention obtained from the above-mentioned knowledge, as shown in the basic configuration diagram of FIG. 1, has a wheel acceleration / deceleration detecting means for detecting the acceleration / deceleration of the wheel and the wheel concerned. Vehicle predetermined traveling state determination means for determining that the vehicle is in the predetermined traveling state when the wheel acceleration / deceleration detection value from the acceleration / deceleration detection means is within a predetermined range indicating the predetermined traveling state of the vehicle for a predetermined time. And a tire air pressure detection unit that detects a tire air pressure of a detection target wheel when the vehicle predetermined traveling state determination unit determines that the vehicle is in the predetermined traveling state. .

[0009]

In the vehicle tire air pressure detection device according to the present invention, as shown in the basic configuration diagram of FIG. 1, the vehicle predetermined traveling state determination means determines the wheel acceleration / deceleration detection value based on the wheel acceleration / deceleration detection value. The wheel deceleration detection value is for a predetermined time, a predetermined range indicating a predetermined traveling state of the vehicle (for example, a value indicating the natural deceleration state of the vehicle is centered, and the rolling resistance and the wheel load of the wheel that fluctuate in an actual vehicle are When it is within the range), it is determined that the vehicle is in the predetermined traveling state, and the tire air pressure detection means detects the tire air pressure of the detection target wheel based on the rolling radius and rolling resistance of the wheel. It That is, the running state of the vehicle (for example, the natural deceleration state) is determined without various sensors for detecting the running state of the vehicle as in the related art.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a vehicle tire pressure detecting device according to the present invention will be described below with reference to the drawings. First, the first embodiment will be described with reference to FIGS. FIG. 2 is a schematic configuration diagram showing the tire air pressure detection device for a vehicle according to the first embodiment. As can be seen from this FIG.
A wheel speed sensor 2 for the front left wheel to the right rear wheel, which is arranged on each wheel (not shown) and detects the rotational speed of each wheel as an angular velocity.
1FL to 21RR and each of these wheel speed sensors 21FL to 21FL
A controller 30 that detects a tire air pressure state of each wheel (here, whether or not the air pressure is lower than a reference value by a predetermined value or more) based on the detected rotational angular velocity values ω _{FL to} ω _{RR from} 21RR. And a display device 40 for displaying the tire air pressure state of each wheel output from the vehicle toward the driver (in this case, displaying the wheel whose tire air pressure has dropped to a predetermined value or more).

Each of the wheel speed sensors 21FL to 21RR
Is a wheel acceleration / deceleration detecting means in the present invention, and as shown in FIG. 3, it is individually attached to a predetermined position of a drive shaft (not shown), and faces a rotor 21a having serrations formed on the outer periphery thereof. It includes a magnet 21b and a coil 21c for detecting an induced electromotive force due to the generated magnetic flux. And the coil 21c
The induced electromotive force (sinusoidal wave signal) having a frequency corresponding to the rotation speed of the serration generated in is converted into a pulse signal by a waveform shaping circuit (not shown), and the rotational angular velocity ω _{FL of the} wheel obtained based on this pulse signal. ~ Ω _RR is the controller 3
It is output to 0.

The controller 30 is composed of a microcomputer, and as shown in FIG.
Input side interface circuit 30 having a D / D conversion function
a, an output side interface circuit 30b having a D / A conversion function, an arithmetic processing unit 30c, and a storage unit 31d.
It is provided with. Then, the input side interface circuit 30a includes the wheel speed sensors 21FL to 21RR.
The rotational angular velocity detection values ω _{FL to} ω _RR output from are input. Also, from the output side interface circuit 30b,
To the display device 40, a wheel pressure drop wheel position signal S indicating which one of the front left wheel and the rear right wheel is the wheel whose tire air pressure has dropped below a predetermined value.
_Sj is output.

The arithmetic processing unit 30c executes the arithmetic processing of FIG. 5, which will be described later, to detect the rotational angular velocity detection values ω _{FL to} ω from the wheel speed sensors 21FL to 21RR at predetermined time intervals ΔT _S.
RR is read, and based on these detection values, it is determined whether the vehicle is in a natural deceleration state, and the wheels whose tire air pressure has dropped below a predetermined value are detected. Further, the storage device 30d stores in advance programs necessary for the arithmetic processing of the arithmetic processing device 30c, each set value, data indicating control characteristics, and the like, and sequentially stores the arithmetic results required in the arithmetic process.

As can be seen from FIG. 2, the display device 40 includes a display device 41 for converting the reduced air pressure wheel position signal S _Sj output from the controller 30 into display data.
A liquid crystal panel 42 that displays display data from the display 41 is provided, and the liquid crystal panel 42 is provided on an instrument panel in the vehicle body. Next, the basic principle of the vehicle tire pressure detecting device of the first embodiment will be described.

In order to detect the tire air pressure based on the rolling radius and rolling resistance of the wheel, it is premised that the variation of the rolling radius and rolling resistance is caused only by the variation of the tire air pressure. There is a need. That is, at least the wheel needs to be in a so-called free rolling state in which the force acting on the wheel is only rolling resistance and wheel load (to be exact, its reaction force). When the wheels are in such a free rolling state, the vehicle is in a so-called natural deceleration state, and the resistance force R (unit: kgf) acting on the vehicle at this time is represented by the following equation (1).

R = c ₁ · W + c ₂ · V ² (1) (where, c ₁ : rolling resistance coefficient of wheels W: vehicle weight (unit: kgf) c ₂ : air resistance coefficient of vehicle body V: vehicle speed ( Unit: km / h)) Acceleration a (unit: m / se) that occurs in the vehicle at this time
c ² ) is represented by the following equation (2) based on the equation (1), where m is the mass of the vehicle.

A = (c ₁ · W + c ₂ · (3.6) ² · V ² ) / m (2) As can be seen from the equation (2), the acceleration a of the vehicle in the natural deceleration state (during deceleration) Therefore, a <0) is largely changed according to the vehicle speed. Also, the air resistance coefficient c
_{Although 2} is a value that is substantially determined for each vehicle body, the rolling resistance coefficient c _{1 of the} wheel changes due to changes in tire air pressure, and the vehicle weight W also changes depending on the number of passengers and the like. Therefore, in consideration of the change in the rolling resistance coefficient c ₁ of the wheel and the change in the vehicle weight W, the acceleration a (<0) when the vehicle represented by the formula (2) is in the natural deceleration is taken into consideration. When the acceleration a is less than “0” and the absolute value | a | thereof falls within the range indicated by (3) below, it is assumed that the vehicle is in the natural deceleration state.

A _MIN ≤ | a | ≤a _MAX (3) Here, a _MIN is the lower limit value of the deceleration (absolute value of negative acceleration) of the vehicle in the natural deceleration state, and the tire pressure is specified. Value (set value for each vehicle, for example 2.0 kgf / c
m ² ), which is a value for one occupant having the smallest vehicle weight. Further, a _MAX is the upper limit value of the deceleration (absolute value of negative acceleration) of the vehicle in the natural deceleration state, and when the tire air pressure is reduced by a predetermined value (for example, the tire air pressure is reduced by 0.5 kgf / cm ^2). Value) when the vehicle weight is maximum.

Further, in this embodiment, the detected value b of the wheel acceleration detected during traveling (positive value during acceleration, negative value during deceleration) is within the range represented by the following equation (3 '). In this case (corresponding to the case where the acceleration a of the vehicle is within the range of the formula (3)), it is determined that the vehicle is in the natural deceleration state and the wheels are in the free rolling state. It was decided to detect the air pressure state.

B ₁ ≤b ≤b ₂ (3 ') (however, b ₁ = -a _MAX , b ₂ = -a _MIN ) Specifically, each detected by the wheel speed sensors 21FL to 21RR. The rotational angular velocities ω _{FL to} ω _RR of the wheels are differentiated by, for example, a digital high-pass filter constructed by a predetermined program to obtain the rotational angular acceleration α of each wheel.
_j (α _{FL to} α _RR ) is calculated, and if this is within the range of the reference vehicle angular accelerations K _{1 to} K ₂ expressed by the following equation (4),
It was decided to determine that the vehicle is in the natural deceleration state and the wheels are in the free rolling state.

K ₁ ≤α _j ≤K ₂ (4) (where K ₁ = b ₁ / r ₀ , K ₂ = b ₂ / r ₀ ,
r ₀ is a prescribed rolling radius: a rolling radius of the wheel when the tire air pressure has a prescribed value. As described above, since the acceleration a of the vehicle in the natural deceleration state is a function of the square of the vehicle speed, the lower limit value K ₁ and the upper limit value K ₂ of the reference vehicle angular acceleration are set according to the vehicle speed. I decided. Therefore, the storage device 30d stores a reference vehicle angular acceleration K-vehicle speed V characteristic curve for each vehicle specification such as a prescribed rolling radius r ₀ as shown in the graph of FIG. Therefore, the lower limit value K ₁ and the upper limit value K ₂ are set according to the vehicle speed V.

Since the vehicle speed V is an average value of the rotational speeds of the four wheels, the wheel speed sensors 21FL to 21RR are used.
From the rotational angular velocity detection values ω _{FL to} ω _RR from, the following (5)
It was decided to calculate from the formula. V = (ω _FL + ω _FR + ω _RL + ω _RR ) / 4 (5) Further, in order to improve the reliability of the data, when the vehicle speed is in a predetermined range that is neither too slow nor too fast, The vehicle speed V calculated from the equation (5) is equal to or higher than a predetermined value V ₁ (for example, a value corresponding to 40 km / h) and a predetermined value V ₂ (for example, 120 k
It is decided to use data that is less than or equal to a value corresponding to m / h).

Then, the running condition of the vehicle can be determined more accurately.
In order to perform (whether or not the vehicle is in the natural deceleration state),
Sampling time ΔT_SFor each wheel speed sensor 21FL
Rotational angular velocity detection value ω from ~ 21RR_FL~ Ω_RRRead
If the vehicle speed V is within the above range for a predetermined time t₀In succession
Only when the read angular velocity detection value ω_FL~
ω _RRFrom the rotational angular acceleration α_j(Α_FL~ Α_RR)
The minimum value of each wheel (absolute value of negative acceleration,
The maximum value for deceleration) M_j(M_FL~ M_RR) Is selected
And this M_j(M_FL~ M_RR) Is the standard vehicle
Lower limit K of both angular acceleration₁That is the upper limit value K₂Below
Whether or not to decide is determined by the following formula (4 ').

K₁≤ M_j≤K₂ (4 ') The tire pressure in the first embodiment is determined as follows.
Judgment of vehicle running state as described above (in natural deceleration state
Whether or not) is determined to be a natural deceleration state
Is the rotational angular velocity detection value ω used for the determination._FL~ Ω_RR
For each wheel, the average value of the rotational angular velocities H_j(H_FL~
H_RR) Is calculated from the following equation (6), and H_j= (Ω_j1+ Ω_j2＋ …… ＋ ω_jn) / N (6) (where n is the number of samplings during a predetermined time t) The average value of the rotational angular velocities of the wheels obtained from the equation (6) H
_j(H_FL~ H_RR), The average value of the four wheels is
Calculated from the equation (7), this is the reference value H for air pressure determination. _K
And H_K= (H_FL+ H_FR+ H_RL+ H_RR) / 4 (7) Average value of each rotational angular velocity H_j(H_FL~ H_RR) About this
Reference value H_KDeviation from ΔH_j(ΔH_FL~ ΔH_RR) Is calculated
And this deviation ΔH_j(ΔH_FL~ ΔH_RR) Is a predetermined value ΔH_K
If above, the tire air pressure of the wheel is a predetermined value (ΔH
_KValue of 0.5 kgf / cm, for example²)
Air pressure that indicates the position of the wheel, assuming that it has decreased
Lower wheel position detection value S_jIt was decided to output.

Next, based on such a basic principle, it is determined whether or not the vehicle is in the natural deceleration state, and only when it is determined that the vehicle is in the natural deceleration state, the tire air pressure state of the wheel is determined. The arithmetic processing performed in the arithmetic device for making a determination during traveling will be described with reference to the flowchart of FIG. It should be noted that this calculation process takes a predetermined time ΔT.
This is executed as a timer interrupt process for each _S (for example, 20 msec), and the counter n in this calculation process is the vehicle speed V.
Is for counting the number of consecutive samplings within the predetermined range, and the time t during which the vehicle speed V is continuously within the predetermined range is calculated as t = n · ΔT _S. When the ignition switch is turned on, n = 0 is set, and when t ≧ t ₀ or when the vehicle speed V is outside the predetermined range, it is reset to n = 0. Further, as described later, the rotational angular velocity detection value ω _FL ~ω _RR is, but each of which is stored at the address provided for each wheel in the RAM of the storage device 30d, the stored rotational angular velocity detected value ω _FL ~ω _RR shall be cleared by turning off the ignition switch.

In the arithmetic processing of FIG. 5, first, step S1
At 01, the rotational angular velocity detection values ω _{FL to} ω _RR for each wheel are read from the wheel speed sensors 21FL to 21RR.
Then, the process proceeds to step S102, and step S1 is performed.
The vehicle speed V is calculated from the equation (5) based on the detected rotational angular velocity values ω _{FL to} ω _RR read at 01. Next, the process proceeds to step S103, and the vehicle speed V calculated in step S102 is not less than the predetermined value V ₁ and the predetermined value V ₂
It is determined whether or not it is within the following predetermined range, and if it is within the predetermined range, the process proceeds to step S104, and if not, the process proceeds to step S105.

In step S104, the rotational angular velocity detection values ω _{FL to} ω _RR read in step S101 are
After storing in the RAM of the storage device 30d at the address provided for each wheel, the process proceeds to step S106. In step S106, "1" is added to the count value n of the counter n. Next, the process proceeds to step S107, and the value obtained by multiplying the count value n by the counter n by the sampling time ΔT _S (that is, the time during which the vehicle speed V is continuously within the predetermined range) is the predetermined value t ₀ or more. It is determined whether or not n · ΔT _S ≧ t ₀ , step S10.
Go to 8, otherwise return to the main program.

In step S108, the counter n is reset to "0". Next, the process proceeds to step S109, and the 4n rotational angular velocity detection values ω _{j1 to} ω _jn (ω _{FL1 to} ω) stored at the respective addresses in step S104.
_RRn ) is read. Then, the process proceeds to step S110,
Rotational angular velocity detection value ω read in step S109
_The rotational angular accelerations α _{j1 to} α _jn (α _{FL1 to} α _RRn ) are calculated by differentiating _{j1 to} ω _jn (ω _{FL1 to} ω _RRn ), respectively.

Next, the process proceeds to step S111, and the rotational angular accelerations α _{j1 to} α j calculated in step S110 are calculated.
_{For jn} (α _{FL1 to} α _RRn ), the minimum value M _j (M _{FL to} M _RR ) is selected for each wheel. Next, step S11
4 is selected from the storage device 30d in accordance with vehicle specifications such as the specified rolling radius r ₀ input in advance.
From the reference vehicle angular acceleration K- vehicle speed V characteristic curve shown in the lower limit value K ₁ of the reference vehicle angular acceleration in accordance with the latest vehicle speed V calculated in the step S102, sets the upper limit value K _2.

Next, the process proceeds to step S113, and the minimum value M _j (M _{FL to} M _RR ) of the rotational angular acceleration for each wheel selected in step S111 is set in step S112.
It is determined whether or not it is within a predetermined range of the lower limit value K ₁ or more and the upper limit value K ₂ or less of the reference vehicle angular acceleration set by the above, and the minimum rotational angular acceleration value M _j (M _FL ~ If all M _RR ) are within the above range, the process proceeds to step S114,
Otherwise (that is, at least one of them is out of the range), the program returns to the main program.

In step S114, the detected rotational angular velocity values ω _{j1 to} ω _jn (ω are read in step S109.
_{From FL1 to} ω _RRn ), the average value H _j (H _{FL to} H _RR ) of the rotational angular velocities is calculated for each wheel based on the equation (6).
Then, the process proceeds to step S115, and step S1 is performed.
Rotational angular velocity average value H _j (H _j (H
_{From FL to} H _RR ), the average value of the average value H _j (H _{FL to} H _RR ) in the four wheels is calculated as a reference value H _K for air pressure determination based on the above equation (7).

Next, the routine proceeds to step S116, where each rotation angular velocity average value H _j (H
_{FL to} H _RR ) from the reference value H _K calculated in step S115, ΔH _j (ΔH _{FL to} ΔH _RR )
Is calculated from the following equation (8). ΔH _j = H _j −H _K (8) Next, the process proceeds to step S117 and step S116.
It is determined whether or not the deviation ΔH _j (ΔH _{FL to} ΔH _RR ) calculated by the above is greater than or equal to the predetermined value ΔH _{K, and the} deviation ΔH _j is calculated.
If at least one of H _j (ΔH _{FL to} ΔH _RR ) is greater than or equal to the predetermined value ΔH _{K, the} process proceeds to step S118, and if not (that is, the deviation ΔH _j (ΔH _FL)
～DerutaH _RR) of all return to it if) the main program is less than the predetermined value [Delta] H _K.

In step S118, the steps
The deviation ΔH in S117_j(ΔH_FL~ ΔH_RR) Is a predetermined value
ΔH_KThe tire pressure of the wheel determined to be above is a predetermined value
(ΔH _KIs a value corresponding to, for example, 0.5 kgf / c
m²) Indicates the position of the wheel as if it has decreased more than
Air pressure drop Wheel position detection value S_jAnd then main
Return to the program.

On the other hand, in step S105, the counter n is reset to "0" and then the process proceeds to step S119. In step S119, the rotational angular velocity detection values ω _{FL to} ω _RR stored in the respective addresses in step S104 up to this point are cleared, and then the process returns to the main program.

Next, the operation of the tire air pressure state detecting device in the first embodiment will be described below. Since the vehicle is traveling straight on a flat road surface at a vehicle speed of about 70 km / h, there is no input from the road surface to the wheels, neither driving force nor braking force is applied, the wheels are in a free rolling state,
When the vehicle is in the natural deceleration state, in the arithmetic processing of FIG. 5 performed by the arithmetic processing device 30c in the controller 30, the rotational angular velocity detection values ω _{FL to} ω _RR of the wheels read in step S101 are used. The vehicle speed V calculated in step S102 is determined in step S103 to be in the range of the predetermined value V ₁ or more and the predetermined value V ₂ or less, and in step S104, the rotational angular velocity detection values ω _{FL to} ω. _{The RR} is stored in the RAM of the storage device 30d at each address provided for each wheel.

When the vehicle speed V calculated in step S102 is within the above range for a predetermined time t ₀ or more, the steps S107 to S108 are performed.
Then, in step S109, the 4n rotational angular velocity detection values ω _{j1 to} ω stored at the respective addresses are detected.
_jn (ω _{FL1 to} ω _RRn ) is read, and step S110
, These rotational angular velocity detection values ω _{j1 to} ω _jn (ω
_{FL1 to} ω _RRn ) are differentiated, and the rotational angular acceleration α
_{j1 to} α _jn (α _{FL1 to} α _RRn ) are calculated, respectively. Then, these rotational angular accelerations α _{j1 to} α _jn (α _{FL1 to} α
_RRn ), in step S111, the minimum value M _j (M _{FL to} M _RR ) is selected for each wheel.

On the other hand, in step S112, from the reference vehicle angular acceleration K-vehicle speed V characteristic curve shown in FIG. 4, the lower limit value K ₁ (of the reference vehicle angular acceleration is calculated according to the latest vehicle speed V calculated in step S102. <0), upper limit value K ₂ (<
0) is set. And in this case, step S
In 113, the minimum value M _j (M _{FL to} M _RR ) of the rotational angular acceleration for each wheel selected in step S111 is
Both are within a predetermined range of the lower limit value K ₁ or more and the upper limit value K ₂ or less of the reference vehicle angular acceleration set in step S112 (that is, the vehicle is in a natural deceleration state).
Then, the determination of the tire air pressure state is started.

That is, in step S114, the detected rotational angular velocity value ω _j1 read in step S109.
From _{~ω jn (ω FL1 ~ω RRn)} , the mean value H _j of the rotational angular velocity for each wheel on the basis of the expression (6) (H _FL to H _RR) is calculated, in step S115, the step S
Rotational angular velocity average value H for each wheel calculated in 114
_{From j} (H _{FL to} H _RR ) the reference value H _K for air pressure determination is calculated based on the equation (7). Next, step S11
6, the rotation angular velocity average value H _j (H _{FL to} H _RR ) calculated in step S114 is set in the step S
Deviation ΔH from the reference value H _K calculated in 115
_j (ΔH _{FL to} ΔH _RR ) is calculated from the equation (8). Then, in step S117, step S1
It is determined whether the deviation ΔH _j (ΔH _{FL to} ΔH _RR ) calculated in 16 is greater than or equal to the predetermined value ΔH _K.

Here, if at least one of the four wheels has a tire air pressure drop above the predetermined value, at least one of the deviations ΔH _j (ΔH _{FL to} ΔH _RR ) is a predetermined value ΔH _K. When it is determined that the above is the case, the deviation ΔH _j (ΔH _{FL to} ΔH _RR ) is calculated in step S118.
For a wheel whose is determined to be equal to or greater than the predetermined value ΔH _K, it is determined that the tire air pressure has decreased by the predetermined value or more, and the air pressure reduction wheel position detection value S _j indicating the position of the wheel is output. Along with this, the air pressure drop wheel position detection value S _j
The air pressure drop wheel position signal S _Sj corresponding to the above is output from the output side interface circuit 30b to the display 41,
Here, the display data is converted into corresponding display data, and the display data is displayed on the liquid crystal panel 42, for example, "There is a tire with reduced air pressure or more: left front wheel".

On the other hand, if there is no decrease in tire air pressure above the predetermined value for all four wheels, the deviation ΔH
_It is determined that all of _j (ΔH _{FL to} ΔH _RR ) are less than the predetermined value ΔH _K , and the air pressure drop wheel position detection value S _j is not output. Even if the vehicle is in the natural deceleration state, the vehicle speed V calculated in step S102 is outside the predetermined range, or the vehicle speed V is outside the predetermined range before the predetermined time t _{0 has} elapsed. The counter n is reset to "0" in step S105,
At 19, the rotational angular velocity detection values ω _{FL to} ω _RR stored at the respective addresses in step S104 are cleared up to this point, so that data for each wheel is newly stored at the next sampling. When the vehicle speed V is within the predetermined range and the predetermined time t _{0 has} elapsed, n pieces of data are always stored in each address.

If the vehicle is not in the natural deceleration state and the state in which the vehicle speed V is within the predetermined range continues for the predetermined time t ₀ or more, the steps are performed as described above. Reaching S109, step S110
Through step S112, in step S113, at least one of the minimum values M _j (M _{FL to} M _RR ) of rotational angular acceleration for each wheel falls within a predetermined range in which K ₁ or more and the upper limit value K ₂ or less. If it is determined that the tire pressure is not present, the determination of the tire pressure state is not started.

As described above, according to the vehicle tire pressure detecting device of the first embodiment, it is determined that the vehicle is in the natural deceleration state by the acceleration of the wheels being within a predetermined range. Therefore, it is not necessary to install various sensors for detecting the running state of the vehicle as in the conventional case. Further, by setting the upper limit value b _{2 of the} acceleration to a negative value, it is possible to easily determine the complete non-driving, so that the tire air pressure is detected when a slight driving force is applied to the vehicle. Can be avoided. Therefore, it is possible to accurately determine a predetermined vehicle traveling state that is a prerequisite for tire pressure detection, improve the accuracy of tire pressure detection, and reduce the cost of the device.

From the above, it is understood that the vehicle tire pressure detecting device of the first embodiment is an embodiment of the device according to the present invention, and step S in the arithmetic processing of FIG.
101 to S110 and S119 correspond to the wheel acceleration / deceleration detecting means of the present invention, steps S111 to 113 correspond to the vehicle predetermined traveling state determining means, and steps S114 to 118.
Corresponds to the tire pressure detecting means.

Next, a second embodiment will be described with reference to FIGS. FIG. 6 is a schematic configuration diagram showing a tire air pressure detection device of this vehicle. As can be seen from this diagram, this device has the same configuration as the first embodiment shown in FIG.
The configuration is such that each wheel load sensor 5FL to 5RR for the rear right wheel is added. As shown in FIG. 7, the wheel load sensors 5FL to 5RR correspond to the load cell 51 fixed to the hub 6 and the load wheel 7 and the load wheel 7 for taking out a detection signal of the load cell 51 to the outside. Slip ring 52 that is rotationally floating (that is, supported asynchronously with the wheels or not rotating at all)
And a connector 53 that connects the slip ring 52 and the controller 30. As such a wheel load sensor, “Axle 6-component force measuring device” manufactured by Tokyo Sokki Kenkyusho Co., Ltd. is commercially available. For example, it is described in Japanese Patent Application Laid-Open No. 4-152103 by the present applicant. It is attached to a vehicle body (not shown) via a supporting device such as the above. Further, in this embodiment, the wheel load sensor 5F
The vertical load applied to each wheel is detected by L to 5RR.

Therefore, as can be seen from FIG. 6, the input side interface circuit 30a of the controller 30 has the rotational angular velocity detection values ω _{FL to} ω _RR output from the wheel speed sensors 21FL to 21RR and the wheel load sensor 5FL to.
The wheel load detection values L _{FL to} L _RR output from the 5RR are input. Further, the arithmetic processing unit 30c executes the arithmetic processing of FIG. 9 described later in place of the arithmetic processing of FIG.

Next, the basic principle of the tire air pressure detecting device of the second embodiment will be described. The second embodiment is an example in which the method for detecting the tire air pressure state is different from that in the first embodiment, and the method for detecting the natural deceleration state of the vehicle, which is the premise thereof, is the same as that in the first embodiment. Therefore, here, the principle relating to the tire air pressure state detection in the second embodiment will be described. In the second embodiment, the tire air pressure state is detected based on the rolling resistance.

In a vehicle equipped with a wheel having a pneumatic rubber tire, even if the wheel is in a free rolling state (a state in which no driving force or braking force is acting on the wheel), the tire is an elastic body, and therefore the road surface is not covered. It deforms upon contact and emits energy corresponding to the amount of deformation as heat energy. This released energy is rolling resistance, which changes depending on the tire air pressure, the load acting on the wheels, and the traveling speed of the vehicle.

There is a relationship between the rolling resistance and the tire air pressure that the rolling resistance decreases when the tire air pressure is increased, and the rolling resistance decreasing rate is about half of the air pressure increasing rate. It is known. Specifically, when the tire air pressure set to 2.0 kgf / cm ² is decreased by 0.5 kgf / cm ² , the rolling resistance increases by about 10%. This is because the rolling radius fluctuation (0.5 kgf / c)
m ² is about 0.2%), which is about 50 times the numerical value. Therefore, if the rolling resistance is used as a detection element of the tire air pressure state, the air state of the tire can be accurately detected.

Here, each wheel j in a free rolling state (that is, a state in which no driving force or braking force acts on the wheel)
For (front left wheel FL to rear right wheel RR), see (9) below.
The equation of motion expressed by the equation holds. I _j β _j = r _j (μ _j L _j + D / 4 + L _j K _S θ ² ) ... (9) (where I _j : moment of inertia of wheel j β _j : angular acceleration of wheel j (deceleration) r _j : rolling radius of tire of wheel j μ _j : rolling resistance coefficient of tire of wheel j L _j : load acting on wheel j (wheel load) D: air resistance applied to the entire vehicle K _S : lateral force θ: slip angle From the equation (9), when the vehicle is in a straight traveling state or a substantially straight traveling state, the slip angle θ or the lateral force K _S
Is almost “0”, the rolling resistance coefficient μ _{j of} wheel _j
Is the wheel deceleration β _j , air resistance (D / 4), and wheel load L
It can be expressed as a function with _j . In addition to this, since the rolling resistance fluctuates according to the vehicle speed and the air resistance is proportional to the square of the vehicle speed, the rolling resistance can be detected based on the wheel deceleration, the vehicle speed, and the wheel load.

Therefore, in this embodiment, the wheel load is
The ratio of the deceleration to be set is a value depending on the rolling resistance coefficient.
It is used as a similar rolling resistance coefficient P, and depending on the detected vehicle speed,
Tire pressure is 0.5 when the wheel load is a standard value such as a design standard value.
kgf / cm²Pseudo rolling resistance coefficient P in case of decrease
₀And the current value calculated from the deceleration detection value and the wheel load detection value.
Pseudo rolling resistance coefficient P of each wheel at time_j(= Β_j/
L_j) Ratio Q_j(= P_j/ P ₀) Is calculated and the rolling resistance is calculated.
This ratio Q corresponding to the resistance ratio_jIf is "1" or more,
Wheel tire pressure is 0.5 kgf / cm²More than
I decided to determine that.

Specifically, as shown in FIG. 8, when the wheel load is a reference value such as a design standard value and the tire air pressure is 0.5 kgf /
A correlation curve between the pseudo rolling resistance coefficient P ₀ and the vehicle speed in the case of a decrease in cm ² is created in advance, and the pseudo rolling resistance coefficient corresponding to the vehicle speed is calculated based on the vehicle speed detection value V from the pseudo rolling resistance coefficient-vehicle speed curve. The reference value P ₀ is set. Then, to calculate the pseudo rolling resistance coefficient P _j corresponding to a rear wheel load detection value L _j and deceleration detecting value beta _j for each wheel, rolling pseudo the set of the calculated pseudo rolling resistance coefficient P _j Ratio of resistance coefficient to reference value P ₀ , that is, rolling resistance ratio Q
By calculating _j , it is determined whether or not this value is "1" or more.

If the rolling resistance ratio Q _j is "1" or more, it is considered that the tire air pressure of the wheel has dropped by a predetermined value or more, and the air pressure indicating the wheel position is lowered as in the first embodiment. It is decided to output the wheel position detection value S _j . Next, based on such a basic principle, it is determined whether or not the vehicle is in the natural deceleration state, and only when it is determined that the vehicle is in the natural deceleration state, the tire air pressure state of the wheel is reduced while traveling. The arithmetic processing performed in the arithmetic device for making the determination will be described with reference to the flowchart of FIG.

It should be noted that this calculation process is performed for a predetermined time ΔT.
This is executed as a timer interrupt process for each _S (for example, 20 msec), and the counter n in this calculation process is the vehicle speed V.
Is for counting the number of consecutive samplings within the predetermined range, and the time t during which the vehicle speed V is continuously within the predetermined range is calculated as t = n · ΔT _S. When the ignition switch is turned on, n = 0 is set, and when t ≧ t ₀ or when the vehicle speed V is outside the predetermined range, it is reset to n = 0. Further, as described later, the rotational angular velocity detection value ω _FL ~ω _RR is, but each of which is stored at the address provided for each wheel in the RAM of the storage device 30d, the stored rotational angular velocity detected value ω _FL ~ω _RR shall be cleared by turning off the ignition switch.

In the arithmetic processing of FIG. 9, first, in step S2
At 01, the rotational angular velocity detection values ω _{FL to} ω _RR for each wheel are read from the wheel speed sensors 21FL to 21RR.
Then, the process proceeds to step S202, and step S2 is performed.
The vehicle speed V is calculated from the equation (5) based on the detected rotational angular velocity values ω _{FL to} ω _RR read at 01. Next, the process proceeds to step S203, and the vehicle speed V calculated in step S202 is not less than the predetermined value V ₁ and the predetermined value V ₂
It is determined whether or not it is within the following predetermined range, and if it is within the predetermined range, the process proceeds to step S204, and if not, the process proceeds to step S205.

In step S204, the detected rotational angular velocity values ω _{FL to} ω _RR read in step S201 are
After storing in the RAM of the storage device 30d at the addresses provided for each wheel, the process proceeds to step S206. In step S206, "1" is added to the count value n of the counter n. Next, the process proceeds to step S207, and the value obtained by multiplying the count value n by the counter n by the sampling time ΔT _S (that is, the time during which the vehicle speed V is continuously within the predetermined range) is the predetermined value t ₀ or more. If n · ΔT _S ≧ t ₀ , then step S20
Go to 8, otherwise return to the main program.

In step S208, the counter n is reset to "0". Next, the process proceeds to step S209, and the 4n rotational angular velocity detection values ω _{j1 to} ω _jn (ω _{FL1 to} ω) stored at the respective addresses in step S204.
_RRn ) is read. Then, the process proceeds to step S210,
Rotational angular velocity detection value ω read in step S209
_The rotational angular accelerations α _{j1 to} α _jn (α _{FL1 to} α _RRn ) are calculated by differentiating _{j1 to} ω _jn (ω _{FL1 to} ω _RRn ), respectively.

Next, in step S211, the rotational angular accelerations α _{j1 to} α j calculated in step S210 are calculated.
_{For jn} (α _{FL1 to} α _RRn ), the minimum value M _j (M _{FL to} M _RR ) is selected for each wheel. Next, step S21.
4 is selected from the storage device 30d in accordance with vehicle specifications such as the specified rolling radius r ₀ input in advance.
From the reference vehicle angular acceleration K- vehicle speed V characteristic curve shown in the lower limit value K ₁ of the reference vehicle angular acceleration in accordance with the latest vehicle speed V calculated in the step S202, sets the upper limit value K _2.

Next, the process proceeds to step S213, and the minimum value M _j (M _{FL to} M _RR ) of the rotational angular acceleration for each wheel selected in step S211 is the same as in step S212.
It is determined whether or not it is within a predetermined range of the lower limit value K ₁ or more and the upper limit value K ₂ or less of the reference vehicle angular acceleration set by the above, and the minimum rotational angular acceleration value M _j (M _FL ~ If all M _RR ) are within the above range, the process proceeds to step S214,
Otherwise (that is, at least one of them is out of the range), the program returns to the main program.

In step S214, the load of each wheel is
Wheel load detection value L from sensors 5FL to 5RR_j(L_FL~ L
_RR) Is read. In step S215, the step
Rotational angular velocity ω read in step S209 _j1~ Ω_jn(Ω_FL1
~ Ω_RRn) Initial value ω_j1(Ω_FL1~ Ω_RR1) And final
Value ω_jn(Ω_FLn~ Ω_RRn) And the count value of counter n
n and sampling time T_SFrom, the acceleration / deceleration β of each wheel
_j(Α_FL~ Α_RR) Is calculated by the following equation (12).

Β _j = (W _jn −W _j1 ) / (n · ΔT _S ) ... (12) Next, the process proceeds to step S216, and the step S2 is performed.
Acceleration / deceleration β _j (β _{FL to} β _RR ) of each wheel calculated in 15
And the wheel load detection value L read in step S214.
_The pseudo rolling resistance coefficient P _j is calculated for each wheel from _j (L _{FL to} L _RR ).

Next, the process proceeds to step S217, and according to the latest vehicle speed V calculated in step S202,
From the pseudo rolling resistance coefficient-vehicle speed curve shown in FIG. 8, a reference value P ₀ of the pseudo rolling resistance coefficient is set. Next, the process proceeds to step S218, and the rolling resistance ratio Q _j (P _j / P _j / P _j / P _j / P _j is calculated from the reference value P ₀ calculated in step S217 and the pseudo rolling resistance coefficient P _j calculated in step S216.
Calculate P ₀ ).

Next, the process proceeds to step S219, and the rolling resistance ratio Q of each wheel calculated in step S218 is calculated.
It is determined whether _j (Q _{FL to} Q _RR ) is “1” or more, and if at least one of the rolling resistance ratios Q _j of each wheel is “1” or more, the process proceeds to step S220. Otherwise (the rolling resistance ratio Q _{j of} each wheel is “1” for all)
Return to main program (if smaller).

In step S220, the steps
In S219, rolling resistance ratio Q_j(Q _FL~ Q_RR) Is “1”
For wheels that are determined to be above, the tire pressure is
(For example, 0.5 kgf / cm²) More than
And the air pressure drop wheel position detection value S indicating the position of the wheel.
_jAnd then return to the main program. one
On the other hand, in step S205, the counter n is set to "0".
After resetting, the process proceeds to step S221.

In step S221, the rotational angular velocity detection values ω _{FL to} ω _RR stored in the respective addresses in step S204 until this point are cleared, and then the process returns to the main program. Next, the operation of the tire air pressure state detecting device in the second embodiment will be described below.

Since the vehicle is traveling straight on a flat road surface at a vehicle speed of about 70 km / h, there is no input from the road surface to the wheels, and neither driving force nor braking force is applied, the wheels are in a free rolling state, When the vehicle is in the natural deceleration state, in the arithmetic processing of FIG. 9 performed by the arithmetic processing device 30c in the controller 30, the rotational angular velocity detection values ω _{FL to} ω _RR of the wheels read in step S201 are used. The vehicle speed V calculated in step S202 is the same as step S20.
3, the predetermined value V ₁ or more and the predetermined value V ₂
It is determined that the rotation angular velocity detection values ω _{FL to} ω _RR are stored in the storage device 3 in step S204.
It is stored in an address provided for each wheel in the 0d RAM.

When the vehicle speed V calculated in step S202 is within the above range for a predetermined time t ₀ or more, the steps S207 to S208 are performed.
Then, in step S209, the 4n rotational angular velocity detection values ω _{j1 to} ω stored in the respective addresses are detected.
_jn (ω _{FL1 to} ω _RRn ) is read, and step S210
, These rotational angular velocity detection values ω _{j1 to} ω _jn (ω
_{FL1 to} ω _RRn ) are differentiated, and the rotational angular acceleration α
_{j1 to} α _jn (α _{FL1 to} α _RRn ) are calculated, respectively. Then, these rotational angular accelerations α _{j1 to} α _jn (α _{FL1 to} α
_RRn ), in step S211, the minimum value M _j (M _{FL to} M _RR ) is selected for each wheel.

On the other hand, in step S212, from the reference vehicle angular acceleration K-vehicle speed V characteristic curve shown in FIG. 4, the lower limit value K ₁ (of the reference vehicle angular acceleration is calculated according to the latest vehicle speed V calculated in step S202. <0), upper limit value K ₂ (<
0) is set. And in this case, step S
In 213, the minimum value M _j (M _{FL to} M _RR ) of the rotational angular acceleration for each wheel selected in step S211 is
Both are within a predetermined range where the reference vehicle angular acceleration set in step S212 is greater than or equal to the lower limit value K ₁ and less than or equal to the upper limit value K ₂ (that is, the vehicle is in a natural deceleration state).
Then, the determination of the tire air pressure state is started.

That is, in step S214, the wheel load detection values L _j (ω _{FL are} detected from the wheel load sensors 5FL to 5RR.
˜ω _RR ) is read, and in step S215, the initial value ω _j1 (ω _{FL1 to} ω _RR1 ) and the final value ω _jn (ω _{FLn to} ω _RRn ) of the rotational angular velocity and the count value n of the counter n are read.
And the sampling time T _S , the acceleration / deceleration β _j (α _{FL to} α _RR ) of each wheel is calculated by the equation (12), and the pseudo rolling resistance coefficient P _j is calculated in step S216.

Then, in step S217, according to the latest vehicle speed V calculated in step S202,
The reference value P ₀ of the pseudo rolling resistance coefficient is set from the pseudo rolling resistance coefficient-vehicle speed curve shown in FIG. 8, and step S219
In, whether the rolling resistance ratio of each wheel calculated in step _{S218 Q j (Q FL ~Q RR} ) is "1" or not is determined.

Here, if at least any one of the four wheels has a tire air pressure drop above the predetermined value, at least one of the rolling resistance ratios Q _j (Q _{FL to} Q _RR ) of each wheel is reduced. For a wheel that is determined to be "1" or more and the rolling resistance ratio Q _j is determined to be "1" or more in step S220, it is determined that the tire air pressure has decreased by a predetermined value or more, and The air pressure drop wheel position detection value S _j indicating the position is output. Along with this, an air pressure lowering wheel position signal S _Sj corresponding to the air pressure lowering wheel position detection value S _j is output from the output side interface circuit 30b to the display 41 and converted into corresponding display data here. According to the display data, it is displayed on the liquid crystal panel 42, for example, "There is a tire with reduced air pressure or more: left front wheel".

On the other hand, if there is no decrease in tire air pressure above the predetermined value for all four wheels, then step S2 is performed.
At 19, it is determined that Q _j <1 for all wheels, and the air pressure drop wheel position detection value S _j is not output. Even if the vehicle is in the natural deceleration state, if the vehicle speed V calculated in step S202 is out of the predetermined range, or if the vehicle speed V is out of the predetermined range before the predetermined time t ₀ elapses. In step S205, the counter n is reset to "0", and in step S219, the rotational angular velocity detection values ω _{FL to} ω _RR stored at the respective addresses in step S204 by this point are cleared, so that the next time At the time of sampling, one data for each wheel is newly stored, and when the vehicle speed V is within the predetermined range for a predetermined time t ₀ , n data are always stored at each address. Will be.

If the vehicle is not in the natural deceleration state and the vehicle speed V remains within the predetermined range for the predetermined time t ₀ or more, the steps are performed as described above. Reaching S209, step S210
Through step S212, in step S213, at least one of the minimum values M _j (M _{FL to} M _RR ) of rotational angular acceleration for each wheel falls within a predetermined range in which the minimum value M _j (M _{FL to} M _RR ) is K ₁ or more and the upper limit value K ₂ or less. If it is determined that the tire pressure is not present, the determination of the tire pressure state is not started.

As described above, according to the vehicle tire pressure detecting device of the second embodiment, as in the first embodiment,
The fact that the vehicle is in the natural deceleration state is determined by the acceleration of the wheels being within a predetermined range, so there is no need to install various sensors for detecting the vehicle traveling state as in the conventional case. . Further, by setting the upper limit value b _{2 of the} acceleration to a negative value, it is possible to easily determine the complete non-driving, so that the tire air pressure is detected when a slight driving force is applied to the vehicle. Can be avoided. Therefore, it is possible to accurately determine a predetermined vehicle traveling state that is a prerequisite for tire pressure detection, improve the accuracy of tire pressure detection, and reduce the cost of the device.

In addition to this, in the second embodiment, the tire air pressure state is detected based on the rolling resistance ratio, so that the tire air pressure state is detected based on the rolling radius as in the first embodiment. Compared with the device, there is also an effect that the tire air pressure state is detected again by a very high detection which is several tens of times higher. From the above, it is understood that the vehicle tire pressure detecting device of the second embodiment is an embodiment of the device according to claims 1 and 2 of the present invention, and steps S201 to S210 in the arithmetic processing of FIG. S221 corresponds to the wheel acceleration / deceleration detecting means of the present invention, and step S2
11 to 213 correspond to the vehicle predetermined traveling state determination means, and steps S214 to 220 correspond to the tire air pressure detection means.

In the first and second embodiments, it is determined whether or not the detected wheel rotation angular acceleration is within the predetermined range of the reference vehicle angular acceleration for all four wheels. The vehicle predetermined traveling state determination means of the present invention is not limited to this. For example, the maximum value and the minimum value are selected from the rotational angular accelerations of the four wheels, and the maximum value and the reference vehicle angular acceleration upper limit value are compared. , And the determination may be made only by comparing the minimum value and the reference vehicle angular acceleration adjustment value.

Further, in the first embodiment, the average value of the detected rotational angular velocities in the predetermined time is averaged by the four wheels on the basis of the rolling radius of the wheel as a reference value. Is determined, in the second embodiment to determine the air pressure drop wheel based on the rolling resistance of the wheel, the tire air pressure detection means of the present invention is not limited to these specific methods, tire air pressure is. Any method that can be detected with high accuracy is applied.

Further, in the first and second embodiments, the state where the tire air pressure is lowered to a predetermined value or more is detected, but the tire air pressure detecting means in the present invention is not limited to this. A specific value of tire air pressure of each wheel may be detected. Further, in the first and second embodiments, the case where the controller 30 is composed of a microcomputer has been described.
The vehicle tire pressure detection device according to the present invention is not limited to this, and may be configured by combining electronic circuits such as an arithmetic circuit.

[0078]

As described above, according to the vehicle tire air pressure detecting device of the present invention, in the device for detecting the tire air pressure based on the rolling radius and rolling resistance of the wheels, the vehicle predetermined traveling state determining means is provided. According to the present invention, a predetermined vehicle traveling state, which is a prerequisite for tire pressure detection, can be easily and accurately determined, and the accuracy of tire air pressure detection can be improved. Since no special sensor is required, the cost of the device can be kept low.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram showing a vehicle tire pressure detection device according to the present invention.

FIG. 2 is a schematic configuration diagram showing the configuration of a first embodiment of a vehicle tire pressure detection device according to the present invention.

FIG. 3 is a schematic diagram showing the structure of a wheel speed sensor used in the first and second embodiments of the vehicle tire pressure detection device according to the present invention.

FIG. 4 shows a vehicle speed-reference vehicle angular acceleration curve used for setting an upper limit value and a lower limit value of a reference vehicle angular acceleration in the first and second embodiments of the vehicle tire pressure detection device according to the present invention. It is a graph shown.

FIG. 5 is a flowchart showing an arithmetic processing procedure executed in the microcomputer of the apparatus of the first embodiment.

FIG. 6 is a schematic configuration diagram showing the configuration of a second embodiment of the vehicle tire pressure detection device according to the present invention.

FIG. 7 is a schematic diagram showing the structure of a wheel load sensor used in the device of the second embodiment.

FIG. 8 is a graph showing a vehicle speed-rolling resistance ratio curve used for setting a reference rolling resistance ratio in the device of the second embodiment.

FIG. 9 is a flowchart showing an arithmetic processing procedure executed in the microcomputer of the apparatus in the second embodiment.

[Description of Reference Signs] 21FL to 21RR Wheel speed sensor (wheel acceleration / deceleration detection means) 30 Controller (wheel acceleration / deceleration detection means, vehicle predetermined traveling state determination means, tire air pressure detection means)

Claims (1)

[Claims] 1. A wheel acceleration / deceleration detection means for detecting acceleration / deceleration of a wheel, and a wheel acceleration / deceleration detection value from the wheel acceleration / deceleration detection means is within a predetermined range indicating a predetermined traveling state of the vehicle for a predetermined time. In the vehicle predetermined traveling state determination means for determining that the vehicle is in the predetermined traveling state, and when the vehicle is in the predetermined traveling state by the vehicle predetermined traveling state determination means, A tire air pressure detection device for a vehicle, comprising: a tire air pressure detection means for detecting a tire air pressure.