JP5224273B2 - Tire demand calculation device and tire demand calculation program - Google Patents

Description

  The present invention relates to a tire demand calculation device and a tire demand calculation program for calculating the demand for the number of replacement tires mounted on a vehicle.

  Conventionally, the demand for tires mounted on vehicles has been predicted and used for tire production plans, sales plans, and the like. The inventors of the present application have proposed a tire replacement number calculating device that calculates the total number of tires to be replaced while the vehicle is present in consideration of the tire replacement cycle and the life of the vehicle (Patent Document 1). reference).

  In the technique of Patent Document 1, the vehicle life and tire life of one vehicle are determined by random numbers, and the tire replacement time while the vehicle is present is determined from the determined vehicle life and tire life. From the replacement time, the number of tires to be replaced while this vehicle is present is determined. This is called one simulation.

This simulation is executed for each of N vehicles registered in the same year t. Further, this simulation is executed for each vehicle registered in the year t + 1,..., Year t + m. By accumulating the results of the executed simulations for a predetermined period, a predicted value of the total number of tires to be replaced in a vehicle existing in the predetermined period is calculated.
Japanese Patent Laid-Open No. 2007-80082

  The method disclosed in Patent Document 1 determines the vehicle life and the tire life using random numbers. The method disclosed in Patent Document 1 calculates the total number of replacements based on the so-called Monte Carlo method. In the Monte Carlo method, a certain condition is set and n simulations are executed. When an event occurs m times, the probability that this event will occur is m / n. For this reason, in order to improve the approximation accuracy of the probability of occurrence of this event, it is necessary to increase the number of simulations n.

  For example, consider the case of calculating the total number of tire replacements on a global scale. In the method disclosed in Patent Document 1, the total number of replacement tires is calculated for each country, and the sum is obtained. In this case, the amount of calculation increases according to the number of countries. This also increases the time period required for the arithmetic processing (for example, on the order of several hours). Although the calculation for each country can be performed in parallel, a plurality of devices of Patent Document 1 must be prepared, leading to an increase in cost.

  The Monte Carlo method requires a corresponding calculation time to obtain a calculation result with high accuracy. Therefore, for example, experimental operations such as calculating the total number of replacement tires by appropriately changing various indicators such as tire type and sales period, and comparing the results are substantially difficult from a time point of view. there were.

  Then, an object of this invention is to provide the tire demand calculation apparatus and tire demand calculation program which can shorten the calculation time of the replacement total number of the tire with which the vehicle was mounted | worn.

  In order to solve the above problems, the present invention is characterized in that a vehicle number setting unit that sets the number of vehicles sold for each predetermined unit period, a period setting unit that sets a first time point and a second time point, A tire replacement total number calculating unit that calculates a total number of tire replacements of the vehicle that is replaced during a predetermined period between the set first time point and the second time point, and the tire replacement total number calculating unit includes: In the vehicle remaining period in which the vehicle remains in accordance with the distribution function representing the distribution of the remaining rate of the vehicle, the number of replacements in the predetermined period of the tire replacement performed according to the distribution function representing the distribution of the tire usage period is calculated. From the replacement number calculation function unit, the number of vehicles remaining at the second time point among the vehicles sold in the predetermined unit period, and the replacement number calculated by the replacement number calculation function unit, the second time point In Replacement number calculation function unit for calculating the number of replacements of tires, and the total number of replacements for calculating the total number of replacements in the predetermined period using the number of replacements calculated in the replacement number calculation function unit The gist is to have a calculation function unit.

  The tire demand calculation device having such characteristics is based on a distribution function that represents a distribution of tire use periods in a vehicle remaining period in which the vehicle remains in accordance with a distribution function that represents a distribution of a remaining ratio of vehicles sold every predetermined unit period. The number of replacements of tires to be executed in a predetermined period is calculated, and the number of replacements of tires at the second time point is calculated from the number of vehicles remaining in the predetermined period and the number of replacements among vehicles sold in a predetermined unit period. And the sum of the number of replacements in a predetermined period is calculated.

  Therefore, according to this feature, the total number of tire replacements in the set predetermined period is analytically calculated from the number of tire replacements performed during the remaining vehicle period in which the vehicle remains and the number of remaining vehicles. Therefore, compared with a method based on the so-called Monte Carlo method, the calculation time for calculating the tire demand can be dramatically shortened.

  In the above-described feature, the distribution of the remaining rate of the vehicle can be a Weibull distribution. Further, the distribution of the tire usage period can be a normal distribution.

Further, the tire demand calculation device having the above-described characteristics is configured such that the number of vehicles sold in the unit period x according to the distribution function representing the distribution of the remaining rate of the vehicle is s (x), and the kth vehicle among the plurality of vehicles is When the average value of the number of replacements up to the second time point t of tire replacement executed in a period according to the distribution function representing the distribution of the tire use period is expressed as H _L (t), It is preferable to approximately calculate the total number U (t) of replacements at the second time point t using the following equation.

  Further, the present invention is characterized in that the computer includes a vehicle number setting unit for setting the number of vehicles sold for each predetermined unit period, a period setting unit for setting the first time point and the second time point, In the vehicle remaining period in which the vehicle remains in accordance with a distribution function that represents the distribution of the remaining rate, a predetermined value that is between the set first time point and the second time point in accordance with a distribution function that represents the tire use period distribution. A replacement number calculation function unit for calculating the number of replacements of tires executed in a period, and the number of vehicles remaining at the second time point and the number of replacements among vehicles sold in the predetermined unit period A replacement number calculation function unit that calculates the number of replacements of the tire at the second time point from the number of replacements calculated in the function unit, and a replacement total number calculation function that calculates the sum of the number of replacements in the predetermined period As part And summarized in that a tire demand calculation program for ability.

  The tire demand calculation program having such characteristics is based on a distribution function that represents a distribution of tire use periods in a vehicle remaining period in which the vehicle remains in accordance with a distribution function that represents a distribution of a remaining ratio of vehicles sold every predetermined unit period. The number of replacements of tires to be executed in a predetermined period is calculated, and the number of replacements of tires at the second time point is calculated from the number of vehicles remaining in the predetermined period and the number of replacements among vehicles sold in a predetermined unit period. And causing the computer to execute a process of calculating the total number of replacements in a predetermined period.

  Therefore, according to this feature, the total number of tire replacements in the set predetermined period can be analytically calculated from the number of tire replacements performed during the remaining vehicle period in which the vehicle remains and the number of remaining vehicles. Can do. Thereby, compared with the method based on what is called a Monte Carlo method, the calculation time at the time of calculating the demand of a tire can be shortened dramatically.

  According to the present invention, it is possible to reduce the calculation time of the total number of tires mounted on a vehicle.

(Configuration of tire demand calculation device)
FIG. 1 is a diagram illustrating an overall configuration of a tire demand calculation device 100 according to the present embodiment. As shown in FIG. 1, the tire demand calculation device 100 includes an input unit 10, a storage unit 20, a processing unit 30, and a display unit 40.

  The input unit 10 acquires information to be described later regarding the vehicle or the tire, and examples thereof include a keyboard.

  The storage unit 20 stores information on a distribution function that represents the distribution of the remaining rate of the vehicle, information on a distribution function that represents the distribution of the tire usage period, and the like.

  The distribution of the remaining rate (also referred to as the life) of the vehicle follows the Weibull distribution, and the distribution of the tire usage period follows the normal distribution. However, the present invention is not limited to this.

  The processing unit 30 includes a vehicle number setting unit 31 that sets the number of vehicles sold for each predetermined unit period, a period setting unit 32 that sets the first time point and the second time point, and the set first time point and the first time point. A tire replacement total calculating unit 33 that calculates the total number of tire replacements of the vehicle that is replaced in a predetermined period between two time points.

  The vehicle number setting unit 31 sets the number of vehicles sold every predetermined unit period. The predetermined unit period is, for example, one year from n years to (n + 1) years, or a half period from n years to (n + 1) years. In this embodiment, it is assumed that the unit period is one year. Therefore, the vehicle number setting unit 31 sets the number of vehicles sold in one year. The number of vehicles may be a value input from the input unit 10 by the user, or may be a value set in advance in a memory or the like (not shown). Further, it may be a predicted number predicted from a predetermined prediction calculation formula. Here, the number of vehicles sold includes not only vehicles sold domestically, but also vehicles manufactured and exported domestically and vehicles manufactured and imported overseas.

  The period setting unit 32 sets a first time point that is a start time point and a second time point that is an end point of calculating the total number of tire replacements. The first time point and the second time point may be values input from the input unit 10 by the user. For example, it is possible to set 20 years before the second time point is the current year and the first time point goes back from the present time.

  The tire replacement total number calculation unit 33 includes a replacement number calculation function unit 331, a replacement number calculation function unit 332, and a replacement total number calculation function unit 333. For example, a CPU (not shown), It is composed of a RAM (not shown), a ROM (not shown), and the like.

  The replacement number calculating function unit 331 applies a predetermined distribution function to each of the set number of vehicles, and when the vehicle remains at a remaining rate according to the distribution function, the use of tires during the remaining time of the vehicle remains. The number of replacements in a predetermined period of tire replacement performed according to a distribution function representing the distribution of the period is calculated.

  The replacement number calculation function unit 332 calculates the second time point from the number of vehicles remaining at the set second time point among the vehicles sold in a predetermined unit period and the replacement number calculated by the replacement number calculation function unit 331. The number of tire replacements at is calculated.

  The replacement total number calculation function unit 333 calculates the total number of replacements in the predetermined period set in the period setting unit 32.

  Accordingly, the tire replacement total number calculating unit 33 having the above-described configuration, for example, when the vehicle number setting unit 31 sets the actual data of the number of vehicles sold every year in the past 20 years, the replacement is performed up to the current year. The total number of tire replacements required for replacement can be calculated. Further, the tire replacement total number calculation unit 33, for example, when the vehicle number setting unit 31 sets prediction data for the number of vehicles sold every year in a predetermined period prior to the present time, the time is changed from the current year. A predicted value of the total number of replacement tires required for replacement at the previous time point can be calculated.

(Operation of tire demand calculation device)
Next, the tire demand calculation process of the tire demand calculation apparatus 100 shown as an embodiment of the present invention will be described. FIG. 2 is a diagram illustrating the operation of the tire demand calculation device 100 in the present embodiment.

  As shown in FIG. 2, in step S1, the tire demand calculation device 100 sets the number of vehicles sold for each predetermined unit period. Next, in step S2, a predetermined period is set. That is, the start point (first time point) and end point (second time point) of the predetermined period are set.

  In the processing after step S3, the tire demand calculation device 100 requires the vehicle set in step S1 between the first time point and the second time point set in step S2 in the tire replacement total number calculation unit 33. Calculate the total number of tire replacements.

  Specifically, in step S3, the tire replacement total number calculating unit 33 represents the distribution of the tire usage period in the vehicle remaining period in which the vehicle remains according to the distribution function representing the distribution of the remaining rate of the vehicle set in step S1. According to the distribution function, the number of tire replacements within the predetermined period set in step S2 is calculated.

  In step S4, the tire replacement total number calculation unit 33 replaces the number of vehicles remaining at the second time set in step S2 among the vehicles set in step S1 and the tire replacement at the second time from the calculated number of replacements. Calculate the total number of replacements.

  In step S <b> 5, the tire replacement total number calculation unit 33 calculates the total sum of the number of replacements in a predetermined period.

(Tire replacement total number calculation process)
The tire replacement total number calculation process executed in the tire replacement total number calculation unit 33 will be specifically described. In the present embodiment, the total replacement number U (t) of tires at time t can be calculated based on the following equation (1).

However, s (x) represents the number of vehicles sold in the same period. In addition, N _x ^(k) (t) is obtained at the second time point t of the tire replacement executed in the period according to the distribution function representing the distribution of the tire usage period for the kth vehicle among the plurality of vehicles. Represents the number of replacements.

Furthermore, the expression (1) can be approximately expressed as the following expression (2) when s (x) (where 0 ≦ x ≦ t) is large. H _L (t−x) represents an average value of the number of tire replacements necessary for a vehicle remaining in a period from year x to year t when the vehicle was sold.

  Hereinafter, the derivation process of Formulas (1) and (2) will be described.

  In a situation where a plurality of vehicles are generated one after another for a predetermined unit period (here, assumed to be an annual unit) as time elapses, it is assumed that each vehicle disappears when the vehicle life is exhausted. In other words, it is assumed that the number of vehicles set in a certain year has a number according to the remaining rate represented by a predetermined distribution function. In the present embodiment, it is assumed that the remaining rate of the vehicle follows the Weibull distribution.

  Further, it is assumed that the tires mounted on each vehicle are replaced with a period of use according to a predetermined distribution function while each vehicle remains. In this embodiment, the replacement of tires follows a normal distribution.

  It should be noted that the tire use period can be considered to include not only the life of the tire from the new state to reaching the use limit due to wear or the like, but also the case of replacement before reaching the end of the life of the tire. Hereinafter, all of these are referred to as “tire life”.

-Average number of tire replacements in one vehicle The vehicle life determined according to the Weibull distribution is represented by L. L is a non-negative random variable that is independent from the column of the tire life Tn (n is a natural number). Here, when a certain vehicle has a vehicle life L, the number of tire replacements performed until the vehicle reaches the vehicle life L is referred to as a renewal process with termination. Further, this life-long regeneration process is defined as the following formula (3).

In Expression (3), N _L (t) represents the number of replacements of a tire that has been replaced by time t (second time point) by one vehicle among vehicles sold in a certain year.

FIG. 3 is a diagram illustrating the number of replacement times N _L (t) that can occur before the vehicle life L in a certain vehicle. T = 0 means when this vehicle is sold. T1, T2,... Represent tire usage periods (tire life) according to a normal distribution, and S1, S2,... Represent years since the vehicle was sold.

When the probability distribution function of the tire life (probability variable: expressed by Tn) is F, Tn (n: natural number) is independent of each other, so the distribution function of the replacement time Sn = T1 + T2 +. N times of the combined product Fn (= F ^{* n} = F * F *... * F).

Distribution P {N _L (t)} of the number N _L (t) of tire replacements performed until the vehicle reaches the vehicle life L is expressed by the following formula (4).

At this time, the expected value E [N _L (t)] (= H _L (t)) of the number of tire replacements NL (t) performed until the vehicle reaches the vehicle life L is expressed by the following equation (5 ). H (t) shown in the following formula (5) is a regeneration function of the regeneration process when there is no vehicle life. G (x) is a distribution function of the vehicle life L and satisfies the following equation.

In Expression (5), H _L (t) represents the average number of replacements of tires that have been replaced by time t (second time) by one vehicle among vehicles sold in a certain year.

Thus, in an infinitesimal section, the average number of replacements (referred to as average regeneration rate) E [dN _L (t)] = dH _L (t) in one vehicle having the vehicle life L is expressed by the following equation (6). Given in.

When the tire life probability distribution function F is absolutely continuous, that is, when the density function f is represented by the following formula (7), the average regeneration rate h _L (t) is represented by the following formula (8). The

However, h (t) in the equation (8) represents an average regeneration rate at the time t when the vehicle life L is not taken into consideration, and is given by the following equation (9).

The variance of the number of tire replacements (lifetime regeneration process) {N _L (t)} t> 0 performed until the vehicle reaches the vehicle life L is given by the following equation (10).

In addition, the variance of the increment of {N _L (t)} t> 0 is given by the following equation (11): the number of tire replacements (lifetime regeneration process) performed until the vehicle reaches the vehicle life L.

When the distribution function F is absolutely continuous, it can be expressed by the following formula (12).

・ Total number of regeneration (total number of tire replacements in multiple vehicles sold in year x)
Next, it is considered to calculate the total number of replacement tires to be replaced at time t in all vehicles sold in a certain unit period based on the average regeneration rate for one vehicle described above.

Let s (x) be the number of vehicles sold in a unit period x (unit “year”). Also, assuming that the number of replacements after the period t of the kth vehicle among the s (x) vehicles is N _x ^(k) (t), the s (x) vehicles are at the time t. The number of tires to be replaced can be expressed by equation (13).

From the sum of the number of replacements represented by formula (13) to the unit period t (including the second time point) of vehicles sold in a certain unit period (including the first time point), from x to t The total replacement number U (t) of tires to be replaced can be obtained. It is represented by Formula (14) (same as Formula (1)).

When it is assumed that the vehicle life of each vehicle is an independent event, the expected value of the replacement total number U (t) can be expressed by the following equation (15) following equation (6).

  Equation (15) adds the average regeneration rate at the time point t of the kth vehicle among vehicles sold in year x to the number of existing vehicles according to the remaining rate represented by the Weibull distribution, and further starts measurement. This means that the total number of tire replacements required up to time t can be calculated by taking the sum in the period from the year (time 0) to time t.

-Average and variance of total number of regenerations (total number of tire replacements in multiple vehicles sold in year x) Also, assuming that vehicle life of each vehicle is an independent event, variance of total replacements U (t) Is the following equation (16).

When the number of vehicles s (x) increases (when s (x) → ∞), the following equation (17) is obtained from the law of large numbers. When the number of vehicles s (x) is large, Equation (18) is approximately established.

When s (x) is sufficiently large, the total number of replacements (equal to the expected value of the total replacement number U (t)) is expressed as Expression (19) by summing both sides of Expression (18) from time 0 to t. The

  Note that the total number here includes the number that is mounted on a newly sold vehicle in advance and the number of replacements that have occurred in accordance with a predetermined life in the previously sold vehicle.

  As described above, according to the present embodiment, the tire demand calculation device 100 is based on the equation (19), and the distribution function G (x) representing the distribution of the remaining rate of vehicles sold for each predetermined unit period. ) To calculate the number of replacements in a predetermined period of tire replacement performed according to the distribution function F (x) representing the distribution of the tire usage period (tire life) in the vehicle remaining period (vehicle life L) in which the vehicle remains. The number of replacement tires at the second time t is calculated from the number of vehicles sold in the unit period x and the number of replacements remaining in the predetermined period, and the total number of replacements in the predetermined period is further calculated. can do.

-Verification of the accuracy of the total number of regeneration (total number of tire replacements) Below, the number of vehicles sold (number of vehicles set) is fixed for each unit period (referred to as “year”) for a predetermined period (assumed as 20 years). t), the average replacement number u (t) (solid line) and the standard deviation (dotted line) are calculated based on the above equations (16) to (19). 4 shows s (t) = 1 (number of vehicles 1), FIG. 5 shows s (t) = 10 (number of vehicles 10), FIG. 6 shows s (t) = 100 (number of vehicles 100), FIG. These are figures which show the calculation result of the total number of replacement | exchange when s (t) = 10000 (vehicle number 10000). However, the vehicle life L follows a Weibull distribution, and the tire life follows a normal distribution.

  The results of FIGS. 4 to 7 show that when the number of vehicles s (x) becomes sufficiently large, the average number of replacements u (t) in the year t becomes equal to the expected total number of replacements in most vehicles. Yes. That is, it means that the total number of tire replacements determined by the equation (19) follows the law of large numbers and the central limit theorem.

  Therefore, the total number of tire replacements calculated analytically based on the above-described equation (19) (same as equation (2)) is comparable to the simulation results of all cases using, for example, the Monte Carlo method. I can confirm that.

Example FIG. 8 shows the total number of replacement vehicles remaining in the year t when the number of vehicles sold (the number of vehicles set) is constant for each year in a predetermined period (20 years). The actual calculation results are shown. In FIG. 8, the second time point is the current year t, and the first time point t = 0 is set 20 years ago. The vehicle sales period is also set to 20 years. The number of vehicles sold is constant every year and is set to 1000 (s (t) = 1000).

  That is, FIG. 8 shows the result of calculating the number of tire replacements that occur in the year t in vehicles that remain after the vehicles are sold under the condition that the vehicles are sold after 1000 vehicles are sold for 20 years each year. It is. However, it is assumed that the vehicle is the same model and tires of the same size are mounted. Further, the vehicle life L follows a Weibull distribution, and the tire life follows a normal distribution.

  FIG. 8 also shows a year earlier in time than the current year. Since a certain number of vehicles are sold until the current fiscal year, the number of tire replacements required in a certain fiscal year starts to decrease as the number of vehicles decreases before the current fiscal year. Then, after a certain period of time has elapsed (in FIG. 8, 20 years from the present), the remaining number of vehicles approaches zero, so the number of tire replacements necessary for that year also approaches zero. The tire demand throughout the year (the total number of tire replacements over the entire year) can be calculated by accumulating the number of tire replacements in each year.

  Thus, according to the tire demand calculation apparatus 100, the total number of tire replacements U (t) in the set predetermined period remains as the number of tire replacements performed until the vehicle reaches the vehicle life L. Since it can be calculated analytically from the number of vehicles, compared with a method based on the so-called Monte Carlo method, the calculation time for calculating the demand for tires can be dramatically shortened.

  For example, using the same personal computer, a calculation method based on the so-called Monte Carlo method and the calculation method for calculating the tire demand using the method of the present embodiment were compared. In the method of the embodiment, the time can be shortened to about 30 seconds. In general, if the performance of a personal computer is higher, the calculation time can be reduced even in the former case. However, as described above, since the method of the present embodiment is inferior to all the simulation results using the Monte Carlo method, the method of the present embodiment is superior in both time cost and economic cost. It can be said that.

  The number of vehicles to be set may be a temporary value as in the example described above, or may be data based on actual sales performance. Further, it may be a predicted value calculated by a predetermined prediction formula. When the predicted value is used, the tire demand at a predetermined time earlier than the present time can be predicted with the first time point as the current time.

  Note that the tire demand calculation device 100 can dramatically reduce the calculation time by an analytical method, so that various indices such as tire type and sales period are appropriately changed to calculate the total number of tire replacements, Experimental operations such as comparing results can be easily performed. In addition, this facilitates, for example, an operation for searching for various index conditions that can obtain the total number of replacements closest to the actual data. Moreover, if the conditions found by the search are used, it is possible to predict the demand for tires at the point of time progressing. In addition, the accuracy of this prediction can be improved.

  Further, the tire demand calculation device 100 in the present embodiment considers only the tire life according to the same distribution curve, but is not limited to this, for example, sets the tire life according to the distribution curve set for each tire size. May be. In this case, the tire demand calculation device 100 can calculate the total number of tire replacements with high accuracy for each tire size from the tire life set for each tire size.

(program)
The tire demand calculation program that operates in the tire demand calculation device 100 sets a vehicle number setting unit 31 that sets the number of vehicles sold for each predetermined unit period, and a first time point and a second time point. It functions as a period setting unit 32 and a tire replacement total calculating unit 33 that calculates the total number of tire replacements of the vehicle to be replaced in a predetermined period between the set first time point and second time point. The tire replacement number calculation program may be provided by being recorded on a recording medium. Examples of the recording medium include a hard disk, a flexible disk, a compact disk, an IC chip, and a cassette tape.

  Although an example of the present invention has been described above, the present invention is not particularly limited, and the specific configuration and the like of each part can be appropriately changed in design. Further, the configuration of the embodiment and the configuration of each modified example can be combined. Further, the actions and effects of the embodiment and each modified example are merely a list of the most preferable actions and effects resulting from the present invention, and the actions and effects according to the present invention are those described in the embodiment and each modified example. It is not limited to.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

It is a figure which shows the structure of the tire demand calculation apparatus in this embodiment. It is a figure which shows operation | movement of the tire demand calculation apparatus in this embodiment. It is a figure explaining the frequency | count _NL (t) of replacement | exchange which can occur by the vehicle lifetime L in a certain vehicle. The tire demand calculation apparatus which concerns on embodiment of this invention WHEREIN: The figure which shows the result of having calculated the average replacement | exchange number u (t) and standard deviation of a tire when one vehicle is produced | generated every year in 20 years. It is. The tire demand calculation apparatus which concerns on embodiment of this invention WHEREIN: The figure which shows the result of having calculated the average replacement | exchange number u (t) and standard deviation of a tire when 10 vehicles are produced | generated every year in 20 years. It is. The tire demand calculation apparatus which concerns on embodiment of this invention WHEREIN: The figure which shows the result of having calculated the average replacement | exchange number u (t) and standard deviation of a tire when 100 vehicles are produced | generated every year in 20 years. It is. The tire demand calculation apparatus which concerns on embodiment of this invention WHEREIN: The figure which shows the result of having calculated the average number of replacement | exchange u of a tire and standard deviation when 10,000 vehicles are produced | generated every year in 20 years It is. In a tire demand calculation device concerning an embodiment of the present invention, it is a figure showing a result of having calculated tire exchange total number U (t) when 1000 vehicles are generated every year in 20 years.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Input part, 20 ... Memory | storage part, 30 ... Processing part, 31 ... Vehicle number setting part, 32 ... Period setting part, 33 ... Tire replacement total calculation part, 331 ... Replacement frequency calculation function part, 332 ... Replacement Number calculation function unit, 333 ... replacement total number calculation function unit 40 ... display unit, 100 ... tire demand calculation device

Claims (5)

A vehicle number setting unit for setting the number of vehicles sold for each predetermined unit period;
A period setting unit for setting the first time point and the second time point;
A tire replacement total calculating unit that calculates a total replacement number of tires of the vehicle that is replaced in a predetermined period between the set first time and the second time;
The tire replacement total number calculating unit
The average per vehicle at the second time point of the tire replacement executed according to the distribution function representing the distribution of the tire use period in the vehicle remaining period in which the vehicle remains according to the distribution function representing the distribution of the remaining ratio of the vehicle. A replacement number calculation function unit for calculating the number of replacements;
Of the vehicles sold in the predetermined unit period, the number of replacement tires at the second time point is calculated from the number of vehicles remaining at the second time point and the average replacement number calculated by the replacement number calculation function unit. A replacement number calculation function part to be calculated;
A tire demand calculation device, comprising: a replacement total number calculation function unit that calculates a sum of the replacement numbers in the predetermined period using the replacement number calculated in the replacement number calculation function unit.   The tire demand calculation device according to claim 1, wherein the distribution of the remaining rate of the vehicle follows a Weibull distribution.   The tire demand calculation device according to claim 1, wherein the distribution of the tire use period follows a normal distribution. S (x) represents the number of vehicles sold in the unit period x according to the distribution function representing the distribution of the remaining rate of the vehicle, and follows the distribution function representing the distribution of the tire usage period for the kth vehicle among a plurality of vehicles. When the average value of the number of replacements up to the second time point t of tire replacement performed in a period is expressed as HL (t),
2. The tire demand calculation according to claim 1, wherein the tire replacement total number calculation unit approximately calculates the total number U (t) of the replacement numbers at the second time point using the following formula. apparatus.

Computer
A vehicle number setting unit for setting the number of vehicles sold for each predetermined unit period;
A period setting unit for setting the first time point and the second time point;
In the vehicle remaining period in which the vehicle remains in accordance with a distribution function that represents the distribution of the remaining ratio of the vehicle, between the set first time point and the second time point in accordance with a distribution function that represents a tire use period distribution. A replacement number calculation function unit that calculates an average number of replacements per vehicle for tire replacement executed in a predetermined period;
Of the vehicles sold in the predetermined unit period, the number of tire replacement at the second time point is calculated from the number of vehicles remaining at the second time point and the average number of replacement times calculated by the replacement number calculating function unit. A replacement number calculation function part to be calculated;
A tire demand calculation program that functions as a replacement total number calculation function unit that calculates the total number of replacements in the predetermined period.

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