JPH07159195A - Running distance measuring speed - Google Patents

Abstract

PURPOSE:To correct running distance for obtaining a high-precision running distance of a vehicle constantly by reading a specified correcting coefficient value in accordance with an actually detected vehicle speed or temperature from a table, and multiplying a measured running distance by the correcting coefficient value. CONSTITUTION:A sound speed sensor 1 generates pulse signals in accordance with rotation of tire. A temperature sensor detects tire temperature. Correcting coefficient values for the running distance with relation to the vehicle speed and temperature are set preliminarily in tables in ROM. A signal processing part 3 comprising a micro-computer counts the number of the pulse signals set by the sensor 1 per unit time to determine a running speed of a vehicle. A running distance of the vehicle is measured by counting the pulse signals. It is then corrected in specified procedure by use of the vehicle speed determined by the measured running distance, and the temperature value detected by the sensor 2. The corrected running distance is displayed 4. An operation part 5 gives various input instructions to the processing part 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mileage measuring device for measuring a mileage of a vehicle.

[0002]

2. Description of the Related Art Generally, in this type of mileage measuring device, the number of pulse signals generated according to the rotation of the tire is counted to measure the mileage of the vehicle. The measurement error is caused by the change of.

In particular, the position on the two-dimensional coordinate is obtained by cumulative calculation while measuring the traveling distance of the vehicle and the change in the traveling direction thereof, and the current position of the vehicle is displayed on the map displayed on the screen. For navigation devices that are updated and displayed, the measurement error of the mileage becomes a problem,
Highly accurate mileage measurement is required to improve position accuracy.

Therefore, when accurate mileage measurement is required, a correction coefficient specific to the tire size is set in advance, and a predetermined correction is made according to the size of the tire mounted on the vehicle. It is conceivable to select a coefficient and multiply the measured mileage by the correction coefficient to correct the mileage, but the tire diameter changes due to various factors depending on the running condition of the vehicle. However, it is not sufficient to uniformly perform such correction according to the tire size.

[0005]

The problem to be solved is to count the number of pulse signals generated according to the rotation of the tire to measure the mileage of the vehicle, and to measure the mileage of the vehicle according to the running condition of the vehicle. That is, the diameter changes and a measurement error occurs.

[0006]

According to the present invention, the tire diameter increases due to centrifugal force as the vehicle speed increases, and the air inside the tire expands and contracts due to the environmental temperature of the vehicle running and the friction temperature during running. Focusing on the fact that the tire diameter changes irregularly, the correction of the mileage measured by counting the number of pulse signals generated according to the rotation of the tire is carried out according to the running situation of the vehicle at that time. In order to perform the above, a memory in which each value of the correction coefficient for the vehicle speed or temperature that causes the change in the tire diameter is set in a table is prepared in advance, and it is determined according to the vehicle speed or temperature actually detected when the vehicle is running. The value of the predetermined correction coefficient is read from the table, and the value of the correction coefficient is multiplied by the measured traveling distance to correct the traveling distance.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a mileage measuring device according to the present invention comprises a vehicle speed sensor 1 for generating a pulse signal according to the rotation of a tire and a temperature sensor for detecting a tire temperature (or a temperature near the tire). 2 and each value of the correction coefficient of the traveling distance with respect to the vehicle speed and temperature are set in the internal ROM as a table, and the number of pulse signals sent from the vehicle speed sensor 1 per unit time is counted to drive the vehicle. The speed is calculated, the number of pulse signals is counted, the traveling distance of the vehicle is measured, and the measured traveling distance is stored in the ROM according to the calculated vehicle speed and the temperature detected by the temperature sensor 2, respectively. The signal processing unit 3 including a microcomputer that performs correction in accordance with a predetermined processing procedure using the value of the correction coefficient read from the display unit and the corrected traveling distance are displayed. A display unit 4, is constituted by an operating unit 5 which can provide a variety of input instructions to the signal processing unit 3.

As shown in Table 1, the ROM stores a correction coefficient value α ₁ (α) for a vehicle speed range that is experimentally obtained in advance for a plurality of tire types (here, two types A and B).
₁₁ and α ₁₂ ) are set.

[0009]

[Table 1]

Further, in the ROM, as shown in Table 2, the correction coefficient value α for the temperature range which is experimentally obtained in advance is set.
₂ is set in the table. Note that the correction coefficient values for the temperature range are uniformly set in the table here, but it is more appropriate if each correction coefficient value obtained experimentally for a plurality of tire types is set in the table. It becomes possible to obtain various correction coefficient values.

[0011]

[Table 2]

Further, prior to measuring the mileage of the vehicle,
By inputting the designation signal of the tire type currently mounted on the vehicle to the signal processing unit 3 by the input operation of the operation unit 5, the signal processing unit 3 can be made to select the tire type in the table. There is.

Further, prior to the measurement of the traveling distance of the vehicle, the measured traveling distance is corrected by the input operation of the operating portion 5 in consideration of the change of the tire diameter according to the air condition of the tire. The fine adjustment value α ₃ can be set arbitrarily.

In this case, as a condition for entering the tire air, for example, a stepwise key of high, normal, or low is provided on the operation unit 5, and any one of them is selectively pressed, A predetermined fine adjustment value α ₃ (1.001 for high, 1.000 for normal, 0.999 for low) is automatically set in the signal processing unit 3 according to the operation signal. You may

Each time the signal processing unit 3 counts a predetermined number (4 pulses) of the pulse signal from the vehicle speed sensor 1, the signal processing unit 3 corrects the traveling distance (1.57 m) measured at that time, and the correction is performed. The mileage that you have added will be added to the mileage that was previously measured.

As the correction processing, for example, a correction coefficient α ₁ read from each table in accordance with the vehicle speed and temperature detected at that time when the measured distance is 1.57 m when 4 pulses are counted, It is executed by multiplying α ₂ and the input fine adjustment value α ₃ respectively.

Incidentally, the correction of the measured traveling distance is performed by using either _{one of} the correction coefficients α ₁ or α ₂ read from the table according to the vehicle speed or the temperature detected at that time. You may make it carry out by multiplying by the running distance.

Further, when the measured traveling distance is corrected, the fine adjustment value α ₃ need not be added.

The operation of the mileage measuring apparatus according to the present invention thus constructed will be described below with reference to the flow chart shown in FIG.

First, as an initial setting, a tire type (A) is selected and designated and a fine adjustment value α ₃ is set by an input operation from the operation unit 5. The signal processing unit 3 stores each data of the selected tire type (A) and the fine adjustment value α _{3 in} the internal RAM.

Next, the signal processing unit 3 determines that the initial settings have been made, and then starts counting the pulse signals sent from the vehicle speed sensor 1, and when the predetermined four pulses are counted. After clearing the count,
Calculate the vehicle speed at that time.

Then, the signal processing unit 3 determines the correction coefficient value α ₁ (α ₁₁ ) corresponding to the predetermined vehicle speed range from the vehicle speed table of the selected tire type (A) in the ROM according to the calculated vehicle speed. ) Is read.

Next, the signal processor 3 reads the temperature detected by the temperature sensor 2 and reads the correction coefficient value α ₂ corresponding to the predetermined temperature range from the temperature table.

The signal processing unit 3 obtains the obtained correction coefficient α ₁ ,
Using α ₂ and the fine adjustment value α ₃ , correction of the measurement distance of 1.57 m for 4 pulses is performed by 1.57 m × α ₁ × α ₂ × α _3.
By performing the calculation of.

When the vehicle is traveling, the signal processing unit 3 repeats the above-described measurement of the traveling distance for every four pulses and its correction processing, and the corrected measured distance for each four pulses is measured first. While cumulatively adding to the running distance, the total running distance that is sequentially added is updatedly displayed on the display unit 4.

[0026]

As described above, according to the present invention, the correction of the traveling distance measured by counting the number of pulse signals generated according to the rotation of the tire is performed, and the tire diameter is changed according to the detected vehicle speed and temperature. With an appropriate correction coefficient value that follows the above, it is possible to perform it according to the running condition of the vehicle at that time, and there is an advantage that it is possible to always obtain a highly accurate measured value of the running distance of the vehicle.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a mileage measuring device according to the present invention.

FIG. 2 is a diagram showing a flow of operations of the mileage measuring apparatus according to the present invention.

[Explanation of symbols]

 1 vehicle speed sensor 2 temperature sensor 3 signal processing unit 4 display unit 5 operation unit

Claims (4)

[Claims] 1. In a mileage measuring device for measuring the mileage of a vehicle by counting the number of pulse signals generated according to the rotation of a tire, a means for detecting the vehicle speed or temperature, and a correction coefficient for the vehicle speed or temperature in advance. Each value of is read out from the memory that is set in the table, and the value of the predetermined correction coefficient corresponding to the detected vehicle speed or temperature is read, and the value of the correction coefficient is multiplied by the measured travel distance A traveling distance measuring device, characterized in that it is provided with means for correcting the distance. 2. Each time a predetermined number of pulses is counted, the travel distance measured at that time is corrected and the corrected travel distance is added to the travel distance measured previously. The mileage measuring device according to the first aspect, characterized in that 3. A table of correction coefficient values for vehicle speed or temperature using the tire type as a parameter is set in the memory, and the vehicle speed or temperature detected from the table corresponding to the input and designated tire type is set. The mileage measuring device according to the above-mentioned item 1 is characterized in that a value of a predetermined correction coefficient according to the above is read out. 4. A means for inputting and setting a fine adjustment value for correction of a measured traveling distance is provided, and the set fine adjustment value is multiplied by the measured traveling distance. The mileage measuring device according to the above item 1.