JPH1120428A - Tire air pressure estimating device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately estimate tire air pressure of each wheel even during rotation of wheels. SOLUTION: The traveling direction of a vehicle is judged (S30). Which one of front and rear wheels is a reference wheel is judged from the time correlation between a protrusion going-over time point based on wheel speed and a protrusion going-over time point based on acceleration-deceleration (S40, 50, 90, 100). Which one of the lateral wheels is a reference wheel is judged on the basis of a code of a voltage signal from an acceleration-deceleration sensor (S60-800 S100-130). Air pressure of other wheels is computed from the tire air pressure Pref of the position specified reference wheel, and the relation between the wheel speed Vwref of the reference wheel and the wheel speed of the other wheels to make an abnormality judgment (S240-290).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for estimating tire pressure of a vehicle, and more particularly to an apparatus for estimating tire pressure of wheels other than the reference wheel based on the tire pressure of at least one reference wheel and the wheel speed of each wheel. The present invention relates to an apparatus for estimating tire pressure.

[0002]

2. Description of the Related Art In a vehicle such as an automobile, there is a fixed relationship between the ratio of the tire pressure of two wheels and the ratio of the dynamic load radius thereof, and the ratio of the dynamic load radius is the wheel speed ratio. Since it is equal to the reciprocal, if the tire pressure of one wheel is known, the tire pressure of the other wheel can be estimated based on the tire pressure and the wheel speed ratio of each wheel.

As one of tire pressure estimating apparatuses based on such a principle, for example, as described in Japanese Patent Application Laid-Open No. 6-191247, a tire pressure sensor provided on one wheel (reference wheel) and a tire pressure sensor provided on each wheel are provided. A tire pressure estimating apparatus having a wheel speed sensor provided and configured to estimate tire pressures of wheels other than the reference wheel based on a tire pressure of the reference wheel and a wheel speed ratio of each wheel is conventionally known. ing.

According to such a tire pressure estimating apparatus, the tire pressures of the wheels other than the reference wheel are estimated based on the tire pressure detected for the reference wheel and the wheel speed of each wheel. In addition, the tire pressures of all the wheels can be estimated and the abnormality can be determined by effectively utilizing the wheel speed sensors provided for each wheel in order to control wheel slippage and the like.

[0005]

Generally, since the main components of the wheel speed sensor are mounted on the wheel supporting member of the vehicle, the wheel speed sensor does not move even when the wheel is rotated. On the other hand, since the tire pressure sensor needs to detect the tire pressure, it is attached to the wheel of the wheel, so that when the wheel is rotated, the tire pressure sensor moves together with the wheel.

However, in the conventional tire pressure estimating apparatus as described above, it is assumed that the reference wheel provided with the tire pressure sensor is always at a specific position, for example, the position of the right front wheel. When the rotation of the wheel is performed and the actual reference wheel moves to another wheel position, it becomes impossible to accurately estimate the tire pressure of each wheel,
It becomes impossible to accurately determine the abnormality of the tire pressure.

The present invention relates to a conventional tire pressure estimating apparatus configured to estimate tire pressures of wheels other than the reference wheel based on the tire pressure of the reference wheel detected by the tire pressure sensor and the wheel speed of each wheel. SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and a main problem of the present invention is to specify a reference wheel position and estimate tire pressures of wheels other than the reference wheel based on the result, thereby rotating the wheel. Is to accurately estimate the tire pressure of each wheel.

[0008]

According to the present invention, there is provided a tire pressure detecting means provided on at least one reference wheel, and a tire pressure detecting means provided on each wheel. Wheel speed detecting means, and a means for estimating tire air pressure of wheels other than the reference wheel based on the tire air pressure of the reference wheel and the wheel speed of each wheel. Means for detecting the acceleration / deceleration of the reference wheel, means for calculating the acceleration / deceleration of each wheel based on the wheel speed detected by the wheel speed detection means, and the detected acceleration / deceleration and the calculated acceleration / deceleration. Means for specifying the position of the reference wheel based on the tire pressure estimation apparatus.

According to the first aspect of the present invention, the reference wheel, that is, the position of the wheel provided with the tire pressure detecting means is specified based on the detected acceleration / deceleration and the calculated acceleration / deceleration. Is performed, even if the reference wheel is moved, the tire air pressures of the wheels other than the reference wheel are accurately estimated based on the tire air pressure detected for the reference wheel after the movement and the wheel speed of each wheel.

According to the present invention, in order to effectively attain the above-mentioned main object, the means for specifying the position of the reference wheel includes the detected acceleration / deceleration and the calculation. Based on the sign relationship of the acceleration / deceleration, the reference wheel is determined to be one of the left and right wheels, and based on the temporal correlation between the detected acceleration / deceleration and the calculated acceleration / deceleration, the reference wheel is It is configured to determine which one is (the configuration of claim 2).

As will be described in detail later, if the means for detecting acceleration / deceleration outputs a positive signal corresponding to the rotational acceleration when the reference wheel is the right wheel and its rotational acceleration is in the forward direction of the vehicle, When the wheel is moved to the left wheel, the means for detecting acceleration / deceleration outputs a negative signal corresponding to the rotational acceleration when the rotational acceleration of the reference wheel is in the forward direction of the vehicle. However, regardless of whether the reference wheel is the right wheel or the left wheel, if the rotational acceleration of the reference wheel is in the forward direction of the vehicle, the acceleration / deceleration calculated based on the wheel speed detected by the wheel speed detecting means is correct. It is. Therefore, it is possible to determine whether the reference wheel is the left or right wheel based on the sign relationship between the detected acceleration / deceleration and the calculated acceleration / deceleration.

When the front wheel gets over a projection on the road surface, the acceleration / deceleration calculated based on the wheel speed detected by the wheel speed detecting means of the front wheel also changes rapidly. When the reference wheel is the front wheel, the detected acceleration / deceleration also changes abruptly at substantially the same time, but when the reference wheel is the rear wheel, the detected acceleration / deceleration changes. A similar rapid change occurs with a delay of the time the vehicle travels a distance corresponding to the wheelbase. Therefore, it is possible to determine whether the reference wheel is the front or rear wheel based on the temporal correlation between the detected acceleration / deceleration and the calculated acceleration / deceleration.

According to the second aspect of the present invention, it is determined which of the left and right wheels is the reference wheel and which of the front and rear wheels is determined, so that the rotation of the wheels is performed. Thus, even if the reference wheel is moved, the position of the reference wheel after the movement is accurately specified.

[0014]

According to a preferred aspect of the present invention, there is provided the above-mentioned claim 1 or 2,
The means for detecting the acceleration / deceleration is configured integrally with the tire pressure detecting means (preferred mode 1).

According to one preferred aspect of the present invention, in the configuration of the first or second aspect, the means for detecting the acceleration / deceleration is configured to detect the rotational acceleration of the reference wheel (preferred aspect 2). .

According to a preferred aspect of the present invention, in the configuration according to the first or second aspect, the means for calculating the acceleration / deceleration of each wheel based on the wheel speed includes calculating the acceleration / deceleration as a time differential value of the wheel speed. It is configured to calculate (preferred mode 3).

According to one preferred aspect of the present invention, in the configuration of the second aspect, the tire pressure estimating apparatus further includes means for detecting a traveling direction of the vehicle, and means for specifying a position of a reference wheel. Is configured to determine whether the reference wheel is the left or right wheel based on the traveling direction of the vehicle, the detected acceleration / deceleration, and the sign relationship of the calculated acceleration / deceleration (preferred mode 4).

According to one preferred aspect of the present invention, in the configuration of the second aspect, the means for specifying the position of the reference wheel is calculated based on the acceleration / deceleration detected when the wheel passes over a protrusion or the like. Whether the reference wheel is the left or right wheel is determined based on the sign relationship of the acceleration / deceleration, and the reference wheel is determined based on the temporal correlation between the acceleration / deceleration detected when the wheel passes over the protrusion or the like and the calculated acceleration / deceleration. Is determined to be one of the front and rear wheels (preferred embodiment 5).

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a schematic diagram showing one embodiment of an apparatus for estimating tire pressure of a vehicle according to the present invention. FIG. FIG. 4 is an explanatory diagram showing a relationship between an output voltage and a sign.

In FIG. 1, the left front wheel 10FL and the right front wheel 10
FR, left rear wheel 10RL, and right rear wheel 10RR have wheel speed sensors 12FL, 12FR, 12RL, 1RL, which detect the wheel speed Vwi (i = FL, FR, RL, RR) of the corresponding wheel as the peripheral speed.
2RR is provided. In the illustrated embodiment, the right front wheel 10FR is set as a reference wheel, and the right front wheel is provided with an air pressure sensor 14 for directly detecting the tire pressure Pref.
And an acceleration / deceleration sensor 16 for detecting an acceleration / deceleration Gw in the rotation direction of the right front wheel.
Are integrally formed with the air pressure sensor 14.

As shown in FIG. 1, a signal indicating the wheel speed Vwi from the wheel speed sensors 12FL to 12RR, a signal indicating the tire pressure PFR from the air pressure sensor 14, and an acceleration / deceleration GFR from the acceleration / deceleration sensor 16 are shown. The signal is input to the tire pressure estimation device 18. Further, a signal indicating the shift position of the transmission is input from the shift position sensor 20 to the tire air pressure estimating device 18.

The tire pressure estimating device 18 calculates the wheel speed V
Based on wi, the tire pressure PFR, the acceleration / deceleration GFR, and the shift position, the wheel (reference wheel) provided with the air pressure sensor 14 and the acceleration / deceleration sensor 16 is specified according to the routine shown in FIG. The tire pressures Pi of the wheels other than the reference wheel are calculated by estimation in accordance with the routine shown in (1), and a control signal is output to the alarm device 22 as necessary, thereby issuing an alarm to the occupant of the vehicle.

The tire pressure estimating device 18 actually includes, for example, a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM) backed up by a power supply, and an input / output port device. And these may be microcomputers connected to each other by a bidirectional common bus.

As shown in FIG. 2, when the reference wheel 10ref rotates in the direction of arrow A when the vehicle is moving forward, the acceleration / deceleration sensor 16 indicates that the rotational acceleration of the reference wheel is viewed from the outside of the vehicle. When it is in the clockwise direction (direction of arrow B), it outputs a positive voltage signal corresponding to the rotational acceleration, and when the rotational acceleration of the reference wheel is counterclockwise (direction of arrow C), it outputs a negative voltage signal in accordance with the rotational acceleration. Outputs a voltage signal.
Therefore, as shown in Table 1 below, it is possible to determine whether the reference wheel 10ref is a right wheel or a left wheel based on the traveling direction of the vehicle and the sign of the voltage signal from the acceleration / deceleration sensor 16.

[0026]

[Table 1]

As shown in FIG. 5A, when the reference wheel is the front wheel 10F and the front wheel 10F gets over the projection 104 of the road surface 102 while the vehicle 100 is traveling forward, the condition shown in FIG. As shown in FIG. 3B, the time t1 at which the phenomenon of the front wheel getting over the protrusion is determined by the acceleration / deceleration calculated based on the wheel speed detected by the front wheel speed sensor 12FL or 12FR, and the acceleration / deceleration sensor 16
The time t2 at which the phenomenon of jumping over the protrusion is determined by the voltage signal is substantially the same as the time t2. Therefore, when the two time points are substantially the same time point, it can be determined that the reference wheel is the front wheel.

On the other hand, when the reference wheel is the rear wheel 10R as shown in FIG.
When the rear wheel 10R moves over the protrusion after the front wheel 10F moves over the protrusion 104 on the road surface 102 during the forward movement of the vehicle, the wheel speed sensor 1 for the front wheel as shown in FIG.
Even if the phenomenon of the front wheel getting over the protrusion is determined by the acceleration / deceleration calculated based on the wheel speed detected by 2FL or 12FR, the voltage from the acceleration / deceleration sensor 16 is substantially the same as the time t1. The signal is not used to judge the phenomenon of over-projection, and the latter determination is made at time t3, which is a time delay when the vehicle travels the distance corresponding to the wheelbase. If not at the same time, the reference wheel is the rear wheel 10
R can be determined.

[0029] When the vehicle goes over the projection while the vehicle is moving backward, the positional relationship of the front and rear wheels with respect to the moving direction of the vehicle is opposite to that when the vehicle is moving forward. When the time of the determination is substantially the same time, the reference wheel can be determined to be the rear wheel, and when the time of the determination of the phenomenon of the overriding of the two projections is not substantially the same, the reference wheel can be determined. Can be determined to be front wheels.

Next, the reference wheel position specifying routine and the tire air pressure estimating routine will be described with reference to the flowcharts shown in FIGS. Note that these routines are started by closing an ignition switch (not shown), and the tire pressure estimation routine shown in FIG. 4 is repeatedly executed at predetermined intervals.

First, in step 10 of the reference wheel position specifying routine shown in FIG. 3, a flag F indicating whether the reference wheel position has been specified is reset to 0, and in step 20 Reads a signal indicating the wheel speed Vwi. In step 30, it is determined whether or not the vehicle is in a forward running state based on a signal from the shift position sensor 20. If a negative determination is made, the process proceeds to step 90; if an affirmative determination is made, Proceed to step 40.

In step 40, it is determined whether the left front wheel or the right front wheel has passed over a protrusion on the road surface based on a signal from the left or right front wheel speed sensor 12FL or 12FR. Return to step 20,
When the determination is affirmative, the routine proceeds to step 50. In step 50, based on the signal from the acceleration / deceleration sensor 16, it is determined whether or not the wheel provided with the acceleration / deceleration sensor has passed over the projection on the road surface substantially simultaneously with the projection on the front wheel. Step 1 when done
Proceeding to step 10, if a positive determination is made, step 60
Proceed to.

In step 60, the acceleration / deceleration sensor 1
It is determined whether or not the voltage signal from 6 is positive. If an affirmative determination is made, it is determined that the right front wheel is the reference wheel. If a negative determination is made, step 80 is executed.
In this case, it is determined that the left front wheel is the reference wheel.

In steps 90 and 100, the same determination is made for the rear wheels as in steps 40 and 50, respectively. When a negative determination is made in step 100, the process proceeds to step 60, and when an affirmative determination is made, Proceed to step 110.

In step 110, the same determination as in step 60, that is, whether or not the voltage signal from the acceleration / deceleration sensor 16 is positive is performed. In this case, it is determined that the left rear wheel is the reference wheel, and when a negative determination is made, it is determined in step 130 that the right rear wheel is the reference wheel.

In step 140, the reference wheel information stored in the RAM of the microcomputer is updated to the determination result in step 70, 80, 120, or 130, and the specification of the reference wheel position is completed. The flag F is set to 1 to indicate that the operation has been performed, and the routine is thereafter terminated.

In steps 40 and 90, acceleration / deceleration based on the wheel speed is calculated, for example, as a time differential value of the wheel speed, and the acceleration / deceleration is calculated based on the normal running of the vehicle. Sometimes when the acceleration / deceleration based on the wheel speed is equal to or greater than the reference value, or when the acceleration / deceleration based on the wheel speed is equal to or greater than the reference value continues for a predetermined time or longer, or when the acceleration / deceleration based on the wheel speed is equal to or greater than the reference value. If the differential value of the acceleration / deceleration based on the wheel speed is equal to or greater than the reference value for a predetermined time or more, it may be determined that the vehicle is over the protrusion.

Similarly, in steps 50 and 100, in the determination of over-projection based on the signal from the acceleration / deceleration sensor, for example, the acceleration / deceleration detected by the acceleration / deceleration sensor 16 does not occur during normal running of the vehicle. If the detected acceleration / deceleration is equal to or greater than the reference value, or if the state where the detected acceleration / deceleration is equal to or greater than the reference value continues for a predetermined time, or if the state where the detected acceleration / deceleration is equal to or greater than the reference value continues for a predetermined time or more. In addition, when the detected differential value of the acceleration / deceleration is equal to or larger than the reference value, it may be determined that the vehicle is over the protrusion.

In step 210 of the tire pressure estimation routine shown in FIG. 4, a signal indicating the wheel speed Vwi is read, and in step 220, the average value of the wheel speeds Vwi of the four wheels is read. The average wheel speed Vwa is calculated in step 230.
Is greater than or equal to a reference value Vwo (positive constant) corresponding to, for example, a vehicle speed of 5 km / h. If a negative determination is made, the process returns to step 210; Proceed to.

In step 240, according to the reference wheel position determined in steps 70, 80, 120 and 130 of the reference wheel position determination routine and updated in step 140, the following table 2 is shown. As described above, the reference wheel speed Vwref is set, and the tire pressure of the reference wheel is set to the value Pref detected by the air pressure sensor 14.

[0041]

[Table 2] Reference wheel reference wheel speed Tire pressure Right front wheel Vwref = VwFR PFR = Pref Left front wheel Vwref = VwFL PFL = Pref Right rear wheel Vwref = VwRR PRR = Pref Left rear wheel Vwref = VwRL PRL = Pref

In step 250, the tire pressure Pi of each wheel other than the reference wheel is calculated by estimation according to the following equation (1).

## EQU1 ## Pi = (Vwref / Vwi) * Pref

In step 260, it is determined whether or not the tire pressure Pi is less than a reference value Poi (positive constant). If a negative determination is made, the process returns to step 210, and an affirmative determination is made. If so, the process proceeds to step 270. In step 270, it is determined whether or not the flag F is 1. When an affirmative determination is made, a control signal for activating the alarm device 22 is output in step 280, so that the occupant of the vehicle is notified. When an alarm is issued indicating that the tire pressure is abnormal, and a negative determination is made, the alarm device 22 is activated in step 290 together with an indication that the position of the reference wheel has not been specified. , An alarm is issued to the effect that the tire pressure is likely to be abnormal. Step 260 is performed for the tire pressures Pi of all the wheels, and if a positive determination is made for at least one of the tire pressures, step 270 is performed.
Is executed.

Thus, in the reference wheel position determination routine of this embodiment, steps 30 to 50, 90, 100
It is determined whether the reference wheel is the front wheel or the rear wheel in the manner described above with reference to FIGS. 5 and 6, and the reference wheel is determined by a combination of step 30 and step 60 or step 110. Since the left or right wheel is determined, the position of the reference wheel can be accurately determined.

In the tire pressure estimation routine of this embodiment, the wheel speed Vwref of the reference wheel and the tire pressure of the reference wheel are determined in step 240 in accordance with the position of the reference wheel specified by the reference wheel position determination routine. Is set, and the tire pressures of the wheels other than the reference wheel are calculated in step 250 according to the setting. Therefore, even if the reference wheel is moved by the rotation of the wheel, the tire pressure of each wheel is accurately calculated, and the tire pressure is calculated. It is possible to accurately determine whether the air pressure is abnormal.

In particular, according to the illustrated embodiment, steps 90 and 100 are executed when the vehicle travels in the reverse direction, and the position of the reference wheel is determined even when the vehicle moves backward. The position can be determined. When the vehicle is moving backward, the vehicle speed is generally low and the traveling distance is generally short. Therefore, if a negative determination is made in step 30, the process returns to step 20, and steps 90 and 100 may be omitted.

Also, according to the illustrated embodiment, step 2
At 70, it is determined whether or not the reference wheel position has been specified. If the reference wheel position has not been specified, a warning is output together with an indication to that effect. When the position is not completely specified, the occupant of the vehicle can surely recognize that there is a high possibility that any of the tire pressures is abnormal, as compared with the case where the warning is not output, and the reference wheel position is determined. If an alarm is output without an indication that the tire has not been identified, the position of the reference wheel is identified and the tire pressure is determined to be abnormal. be able to.

Further, according to the illustrated embodiment, since the acceleration / deceleration sensor 16 is formed integrally with the air pressure sensor 14, even if the wheel is moved by the rotation of the wheel, these sensors are connected to different wheels. It is possible to reliably prevent the vehicle from being mounted, and thereby to reliably specify the position of the reference wheel.

Although the present invention has been described in detail with reference to specific embodiments, the present invention is not limited to the above-described embodiments, and various other embodiments may be included within the scope of the present invention. It will be clear to those skilled in the art that is possible.

For example, in the illustrated embodiment, when a negative determination is made in steps 50 and 100, the process proceeds directly to steps 110 and 60, respectively. When a negative determination is made, the time Δt during which the vehicle travels a distance corresponding to the wheel base is calculated based on H / Vwa with the wheel base of the vehicle set to H, and the time when it is determined that the vehicle is over a protrusion is determined based on the wheel speed. More substantially Δt
After the lapse of time, it is determined whether or not it is determined that the vehicle is going over the protrusion based on the acceleration / deceleration. If a negative determination is made, the process returns to step 20, and if an affirmative determination is made, the process is modified to proceed to steps 110 and 60, respectively. Is also good.

In the illustrated embodiment, when the position of the reference wheel is determined in steps 70, 80, 120 and 130, the position of the reference wheel is updated as it is in step 140. However, the position of the reference wheel is updated only when the determination that the position of the reference wheel is the same position is performed a predetermined number of times in steps 70, 80, 120, and 130. It may be configured as follows.

If the determination in step 230 is affirmative, it is determined whether or not the flag F is 1, that is, whether or not the specification of the position of the reference wheel has been completed.
When an affirmative determination is made, the process proceeds to step 240, and when a negative determination is made, a wheel whose tire pressure is estimated to be the lowest or a wheel whose tire pressure is estimated to be the highest is determined based on the wheel speed ratio between the wheels. It may be configured to determine the reference wheel, and steps 270 and 290 of the embodiment may be omitted.

When the determination in step 230 is affirmative, it is determined whether or not the flag F is 1, that is, whether or not the specification of the reference wheel position has been completed.
When an affirmative determination is made, the process proceeds to step 240, and when a negative determination is made, the tire pressure of each wheel is accurately determined by a disturbance observer method or an FFT (frequency analysis) method based on the wheel speed known in the art. It is configured to estimate and steps 270 and 290 of the embodiment may be omitted. In particular, in the case of the disturbance observer method, the observer may be initialized such that the estimated average value of the tire pressures of the four wheels matches the detection value of the air pressure sensor 14.

[0054]

As is apparent from the above description, according to the structure of the first aspect of the present invention, even if the reference wheel is moved by rotating the wheel, the position of the reference wheel after the movement is obtained. Is specified, the tire pressures of the wheels other than the reference wheel can be accurately estimated based on the tire pressure detected for the reference wheel and the wheel speed of each wheel.

According to the second aspect of the present invention, it is determined whether the reference wheel is the left or right wheel, and it is also determined whether the reference wheel is the front or rear wheel. Even if the reference wheel is moved by performing
The position of the reference wheel after the movement can be accurately specified.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a vehicle tire pressure estimation device according to the present invention.

FIG. 2 is an explanatory diagram showing the relationship between the direction of rotational acceleration of a wheel provided with an air pressure sensor and an acceleration / deceleration sensor and the sign of an output voltage of the acceleration / deceleration sensor.

FIG. 3 is a flowchart illustrating a reference wheel position determination routine according to the embodiment.

FIG. 4 is a flowchart showing a tire pressure calculation routine according to the embodiment.

FIG. 5 is an explanatory diagram (A) and a time chart (B) showing a situation where a front wheel and a rear wheel pass over a projection on a road in this order during forward movement of a vehicle when a reference wheel is a front wheel.

FIG. 6 is an explanatory diagram (A) and a time chart (B) showing a situation in which a front wheel and a rear wheel get over a projection on a road in this order during forward movement of a vehicle when a reference wheel is a rear wheel.

[Explanation of symbols]

 12FL-12RR: Wheel speed sensor 14: Air pressure sensor 16: Acceleration / deceleration sensor 18: Tire pressure estimation device 20: Shift position sensor 22: Alarm device

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazunori Sawafuji 1300-1 Kobe-cho, Anpachi-gun, Gifu 1 Pacific Industrial Co., Ltd.

Claims (2)

[Claims] 1. A tire pressure detecting means provided on at least one reference wheel, a wheel speed detecting means provided on each wheel, and the reference wheel based on a tire pressure of the reference wheel and a wheel speed of each wheel. A tire pressure estimating device having means for estimating tire pressures of other wheels, a means provided on the reference wheel for detecting acceleration / deceleration of the reference wheel, and a wheel speed detected by the wheel speed detecting means. A tire pressure estimating apparatus comprising: means for calculating the acceleration / deceleration of each wheel based on the calculated acceleration / deceleration; and means for specifying the position of the reference wheel based on the detected acceleration / deceleration and the calculated acceleration / deceleration. 2. The means for specifying the position of the reference wheel determines whether the reference wheel is the left or right wheel based on the sign relationship between the detected acceleration / deceleration and the calculated acceleration / deceleration. The tire pressure estimating device according to claim 1, wherein it is determined whether the reference wheel is the front or rear wheel based on a temporal correlation between the acceleration / deceleration and the calculated acceleration / deceleration.