JP5108576B2 - 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 demand for tires mounted on a vehicle.

  Conventionally, a tire manufacturer predicts a demand for a tire to be mounted on a vehicle and uses it for a tire production plan, a sales plan, and the like. Therefore, tire manufacturers want to predict tire demand over a certain period as accurately as possible.

  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

  However, an error occurs between the actual tire demand (referred to as tire sales performance data) and the predicted value. As an example of the cause of the error, there is a change from a standard size tire that is installed in the vehicle to a different size tire that can be changed.

  For example, it is assumed that a tire of a certain vehicle type can be changed from size A (standard size) to size B and from size A (standard size) to size C. This is called a resize pattern. Resizing patterns must be taken into account to calculate accurate forecasts of tire demand.

  The method disclosed in Patent Document 1 calculates the total number of replacements based on the so-called Monte Carlo method. That is, the method disclosed in Patent Document 1 determines the vehicle life and the tire life using random numbers. 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. The technique disclosed in Patent Document 1 needs to increase the number n of simulations in order to increase the approximation accuracy of the probability that this event can occur.

  Therefore, for example, if the method disclosed in Patent Document 1 is used to obtain the total number of replacements, the size change pattern, and the ratio of the change, the amount of computation becomes enormous and takes a processing time that is unsuitable for practical use. End up.

  Therefore, the present invention provides a tire demand calculation device and a tire demand calculation program capable of shortening the processing time when calculating the total number of replacements taking into account the size change of the tire mounted on the vehicle. Objective.

  In order to solve the above-mentioned problem, the feature of the present invention is that the number of vehicles sold every predetermined unit period and a vehicle number setting unit (vehicle number setting unit 31) for setting a predicted value of the number of vehicles, Size data in which a period setting unit (period setting unit 32) that sets the first time point and the second time point is associated with a vehicle type and a standard size that is a tire size that is mounted in advance when the vehicle is sold. A size data acquisition unit (size data acquisition unit 34) that acquires the change table acquisition unit (change table) that acquires the size change table in which the standard size and the change destination size that can be changed from the standard size are associated with each other An acquisition unit 35), a change ratio setting unit (change ratio setting unit 36) for setting a predicted value of a change ratio to be changed from the standard size to the change destination size at the time of tire replacement, A tire replacement total number calculation unit (tire replacement total number calculation unit 33) that calculates a standard replacement total number of the standard size tires to be replaced in a predetermined period between the first time point and the second time point in both; The tire replacement actual number acquisition unit (tire sales result acquisition unit 37) for acquiring the actual sales number of the tires of the standard size sold in the past, and the standard replacement calculated in the tire replacement total number calculation unit The total number of deformation replacements excluding the number of changes calculated according to the predicted value of the change ratio set in the change ratio setting unit from the total number, and the tire of the standard size acquired in the tire sales performance number acquisition unit A change ratio determination unit that compares the number of sales results and determines the predicted value of the change ratio when the total number of modified replacements closest to the number of sales results is calculated as an actual change ratio ( The tire replacement total number calculating unit in the vehicle remaining period in which the vehicle set in the vehicle number setting unit remains in accordance with a distribution function representing the distribution of the remaining rate of vehicles. A replacement number calculation function unit (replacement number calculation function unit 331) that calculates the number of replacements of the standard-size tire at the second time point, which is executed according to a distribution function that represents a distribution of tire use periods; Of the standard size tires at the second time point from the number of vehicles remaining in the second time point and the number of replacement times calculated by the replacement number calculating function unit. The replacement number calculation function part (replacement number calculation function part 332) for calculating the replacement number and the replacement number of the tire of the standard size calculated by the replacement number calculation function part. And a replacement total number calculation function unit (replacement total number calculation function unit 333) that calculates the standard replacement total number in the predetermined period.

  The first feature of the present invention is that the type of vehicles sold for each predetermined unit period and the predicted value of the number of vehicles are set, the first time point and the second time point are set, the first time point and the first time point Calculate the total number of tires of standard size tires to be replaced in a given period between two time points, and remove the number of changes calculated according to the predicted change ratio from the total number of replacements The total replacement number of tires is compared with the number of sales results of standard size tires, and the predicted value of the change ratio when the value closest to the number of sales results is calculated is determined as the actual change ratio.

  Therefore, according to the first feature of the present invention, it is possible to shorten the processing time when calculating the total number of replacements taking into account the size change of the tire mounted on the vehicle.

  The gist of a second feature of the present invention is that, in the first feature of the present invention, the distribution of the remaining rate of the vehicle follows a Weibull distribution.

  The gist of a third feature of the present invention is that, in the first feature of the present invention, the distribution of the period of use of the tire follows a normal distribution.

A fourth feature of the present invention is that, in the first feature of the present invention, s (x) represents the number of vehicles sold in a unit period x in accordance with a distribution function representing the distribution of the remaining rate of the 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 according to a distribution function representing the distribution of the tire usage period is expressed as H _L (t) in the k-th vehicle, The gist of the tire replacement total number calculating unit is to approximately calculate the total number U (t) of the replacement number at the second time point using the following formula.

  According to a fifth aspect of the present invention, there is provided a vehicle number setting unit that sets a type of a vehicle sold for each predetermined unit period and a predicted value of the number of vehicles, a first time point, and a second time point. A period setting unit for setting a time point, a size table acquisition unit for acquiring a size table in which a type of the vehicle and a standard size that is a size of a tire mounted at the time of sale of the vehicle are associated, and the standard size A change table acquisition unit that acquires a size change table associated with a change destination size that can be changed from the standard size, and a change ratio that is changed from the standard size to the change destination size when a tire is replaced. A change ratio setting unit for setting a predicted value; and a standard take of the standard size tire that is replaced in the vehicle in a predetermined period between the first time point and the second time point. The tire replacement total number calculating unit for calculating the total number, the tire sales result number acquiring unit for acquiring the number of actual sales of the tires of the standard size sold in the past, and the standard calculated in the tire replacement total number calculating unit The total number of replacements obtained by subtracting the number of changes calculated according to the predicted value of the change ratio set in the change ratio setting unit from the total number of replacements, and the tire of the standard size acquired in the tire sales performance number acquisition unit In comparison with the actual sales ratio, and function as a change ratio determining unit that determines the actual change ratio as the predicted value of the change ratio when the total number of modified replacements closest to the actual sales number is calculated, The tire replacement total number calculating unit is configured to set the tire replacement period in the vehicle remaining period in which the vehicle remains set in the vehicle number setting unit according to a distribution function representing a distribution of the remaining rate of the vehicle. A replacement number calculation function unit for calculating the number of replacements of the standard size tire at the second time point, which is executed in accordance with a distribution function representing a distribution of the usage period of the vehicle, and the vehicle sold in the predetermined unit period Of these, the replacement number calculation function for calculating the replacement number of the standard size tire at the second time point from the number of vehicles remaining at the second time point and the replacement number calculated by the replacement number calculation function unit. And a replacement total number calculation function unit for calculating the standard replacement total number in the predetermined period from the replacement number of the standard size tire calculated by the replacement number calculation function unit. To do.

  According to a fifth feature of the present invention, the type of vehicle sold for each predetermined unit period and the predicted value of the number of vehicles are set in the computer, the first time point and the second time point are set, and the first The total number of replacement tires of standard size tires to be replaced in a predetermined period between the time point and the second time point is calculated, and the number of changes calculated according to the predicted value of the change ratio is calculated from the calculated total number of replacements. Compare the total number of replacement tires of the standard size tires with the number of sales results of standard size tires, and determine the predicted value of the change ratio when the value closest to the number of sales results is calculated as the actual change ratio Let

  Therefore, according to the fifth feature of the present invention, it is possible to shorten the processing time when calculating the total number of replacements taking into account the size change of the tires mounted on the vehicle.

  According to the present invention, it is possible to shorten the processing time when calculating the total number of replacements taking into account the size change of the tire mounted on the 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 memory | storage part 20 memorize | stores the size table with which the kind of vehicle and the standard size which is the size of the tire with which the vehicle was sold were matched. The storage unit 20 stores a size change table in which a standard size is associated with a change destination size that can be changed from the standard size. The memory | storage part 20 may memorize | store the sales performance number of the tire of the standard size sold in the past.

  Examples of the storage unit 20 include a large-capacity recording medium such as a hard disk, an optical recording medium, and an IC chip, and a recording / reproducing apparatus thereof. The storage unit 20 may be detachable.

  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 type of vehicle sold for each predetermined unit period and the predicted value of the number of vehicles. 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 vehicle type and the number of vehicles sold for 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 (not shown) or the like. In the present embodiment, the predicted number is predicted from a predetermined prediction calculation formula.

  Here, the vehicle type and the number of vehicles include 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. Each configuration of the tire replacement total number calculation unit 33 will be described later.

  The size table acquisition unit 34 acquires, from the storage unit 20, a size table in which a vehicle type and a standard size that is a size of a tire mounted at the time of vehicle sales are associated with each other.

  An example of the size table is shown in FIG. In the size table illustrated in FIG. 2, for example, a standard size “185 / 65R15” and an application year (sales period) 96 to 99 are associated with a model a1 of manufacturer A. Further, the standard size “225 / 45R17” and the applicable year 96 to 02 are associated with the model y1 of the manufacturer B company.

  The change table acquisition unit 35 acquires from the storage unit 20 a size change table in which the standard size is associated with the change destination size that can be changed from the standard size. An example of the size change table is shown in FIG. The size change table shown in FIG. 3 indicates that the standard size “205 / 55R16” can be changed to “225 / 45R17”. Further, it is indicated that the standard size “225 / 40R18” can be changed to “225 / 35R19”.

  The change ratio x is a predicted value of the change ratio that is changed from the standard size to the change destination size when the tire is replaced. In the present embodiment, the change ratio x is appropriately set by the change ratio setting unit 36.

  The tire sales record number acquisition unit 37 acquires the sales record number of standard size tires sold in the past. The number of sales records may be stored in the storage unit 20. Further, it may be input from the input unit 10.

  The change ratio determination unit 38 is a total number of change replacements obtained by subtracting the number of changes calculated according to the predicted value of the change ratio set by the change ratio setting unit 36 from the standard replacement total number calculated by the tire replacement total number calculation unit 33. And the number of sales records of standard size tires acquired by the tire sales record number acquisition unit 37.

  As a result of the comparison, the change ratio determination unit 38 determines the predicted value of the change ratio when the total number of modified replacements closest to the actual sales number is calculated as the actual change ratio (referred to as the actual change ratio).

  Then, each structure of the tire replacement total number calculation part 33 is demonstrated. The number-of-replacements calculation function unit 331 executes in accordance with a distribution function that represents the distribution of tire use periods in the remaining vehicle period in which the vehicle set in the vehicle number setting unit 331 remains in accordance with the distribution function that represents the distribution of the remaining rate of vehicles The number of replacements of the standard size tire at the second time point is calculated.

  The replacement number calculation function unit 332 includes the number of vehicles remaining at the second time point among vehicles sold in a predetermined unit period (for example, one year), and the number of replacements calculated by the replacement number calculation function unit 331. To calculate the number of replacement tires of the standard size at the second time point.

  The replacement total number calculation function unit 333 calculates the standard replacement total number in a predetermined period from the replacement number of the standard size tire calculated by the replacement number calculation function unit 331 in the predetermined period set by the period setting unit 32. To do.

  The tire replacement total number calculating unit 33 having the above-described configuration is replaced in the vehicle number setting unit 31 while the set vehicle type exists from the set vehicle type and the number of sales of this vehicle type. The total number of necessary tire replacements can be calculated.

  The tire replacement total number calculation unit 33 refers to the size table and the size change table, sets the change ratio as appropriate, and replaces the standard size tires excluding the number of changes calculated in each change ratio (modified type). Calculate the total number of replacements. The tire replacement total number calculation unit 33 compares the total number of modified replacements with the sales record number, and determines the size change pattern and the change ratio when the value closest to the sales record number is obtained as the actual change ratio.

  Thereby, the tire replacement total number calculation unit 33 can know a trend of size change such as so-called inch up. In addition, the total replacement number of standard size tires can be calculated based on the trend of size change.

(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 type of vehicle and the number of vehicles.

  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. For example, suppose it is the past 10 years.

  In step S3, the size table acquisition unit 34 acquires a size table and acquires data related to the standard size of the tire mounted on the vehicle type set in step S1.

  In step S4, the size change table acquisition unit 35 acquires a size change table and selects a change destination size (size change pattern) that can be changed from the standard size acquired in step S3.

  In step S5, the change ratio setting unit 36 sets the change ratio x = x0 for the size change pattern selected in step S5. For example, the change ratio is changed every 1% between 1% and 10%. Each time the change ratio is changed, the total number of tire replacements to be described later is calculated and compared with the actual number of sales in the past 10 years.

  In the processing after step S6, the tire replacement total number calculating unit 33 needs the vehicle set in step S1 between the first time point (10 years ago) and the second time point (current) set in step S2. Calculate the total number of tires to be replaced.

  Specifically, in step S6, 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 in accordance with 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 replacements of the standard tire within the predetermined period set in step S2 is calculated.

  In step S7, the tire replacement total number calculating unit 33 determines the second time point (from the number of vehicles remaining at the second time point (current) set in step S2 among the vehicles set in step S1 and the calculated replacement number ( Calculate the total number of standard tire replacements (current).

  In step S8, the tire replacement total number calculation unit 33 calculates the standard replacement total number in the predetermined period set in step S2 from the number of replacement tires of the standard size calculated in step S7.

  Further, the total number of tire replacement part 33 calculates the total number of replacement parts by subtracting the number of changes calculated according to the predicted value of the change ratio set by the change ratio setting part 34 in step S5 from the calculated standard replacement total number. calculate.

  In step S9, it is determined whether or not the change ratio has reached xn. If the change ratio is not xn (step S9: no), in step S12, the change ratio is incremented by 1, and the process returns to step S5, where the change ratio is set again.

  When the total number of deformation replacements is calculated for all the change ratios that can be set (step S9: yes), the sales record of the standard size tire acquired by the tire sales record number acquisition unit 37 in step S10. Compare the number with the total number of each variant replacement.

  In step S11, the change ratio determining unit 36 determines the predicted value of the change ratio when the total number of modified replacements closest to the actual sales number is calculated as the actual change ratio.

(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 this embodiment, the total replacement number U (t) of standard size tires at time t can be calculated based on the following equation (1). The total replacement number U (t) is referred to as the standard replacement total number.

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 the number of tire replacements necessary for the vehicle remaining in the 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. 5 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 N _L (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 (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). 6 shows s (t) = 1 (number of vehicles 1), FIG. 7 shows s (t) = 10 (number of vehicles 10), FIG. 8 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. 6 to 9 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. 10 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. 10, 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. 10 shows the result of calculating the number of tire replacements that occur in the year t in the vehicles that remain after the vehicles are sold under the condition that the vehicles are sold after 1000 vehicles are sold for 20 years every 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. 10 also shows a year earlier 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. 10, 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.

  As described above, the tire demand calculation device 100 can dramatically reduce the calculation time by an analytical method. Therefore, the tire demand calculation device 100 changes various “parameters” such as the type of tire and the sales period, calculates the total number of replacement tires, and compares the calculation result with the actual number of actual sales. Experimental operations such as verifying the accuracy of “parameters” are possible.

  Moreover, if the conditions found by the above-described experimental operation are used, it is possible to predict the demand for tires taking into account not only vehicle life and tire life but also tire size changes. 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 lineblock diagram explaining the tire demand calculation device concerning this embodiment. It is a figure explaining the size table acquired in the tire demand calculation device concerning this embodiment. It is a figure explaining the size change table acquired in the tire demand calculation apparatus concerning this embodiment. It is a flowchart explaining the tire replacement total number calculation process of the tire demand calculation apparatus which concerns on 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, 34 ... Size table acquisition part, 35 ... Size change table acquisition 36, change comparison setting unit, 37 ... tire sales result number acquisition unit, 38 ... change ratio determination unit, 331 ... replacement number calculation function unit, 332 ... replacement number calculation function unit, 333 ... replacement total number calculation function 40, display unit, 100 ... tire demand calculation device

Claims (5)

A vehicle number setting unit for setting the type of vehicle sold for each predetermined unit period and the predicted value of the number of vehicles,
A period setting unit for setting the first time point and the second time point;
A size table acquisition unit for acquiring a size table in which a standard size that is a size of a tire mounted at the time of sale of the vehicle and the type of the vehicle is associated;
A change table acquisition unit that acquires a size change table in which the standard size and a change destination size that can be changed from the standard size are associated;
A change ratio setting unit for setting a predicted value of a change ratio to be changed from the standard size to the change destination size at the time of tire replacement;
A tire replacement total number calculating unit for calculating a standard replacement total number of the standard size tires to be replaced in a predetermined period between the first time point and the second time point in the vehicle;
A tire sales record acquisition unit for acquiring the number of sales of the standard size tires sold in the past;
The total number of modified replacements obtained by removing the number of changes calculated according to the predicted value of the change ratio set by the change ratio setting unit from the standard replacement total number calculated by the tire replacement total number calculating unit, and the tire sales By comparing the number of sales of the standard size tire acquired in the number of results acquisition unit, the predicted value of the change ratio when the total number of deformation replacements closest to the number of sales results is calculated is A change ratio determining unit for determining the change ratio,
The tire replacement total number calculating unit
In the vehicle remaining period set in the vehicle number setting unit according to the distribution function representing the distribution of the remaining ratio of the vehicle, the second time point is executed according to the distribution function representing the distribution of the tire usage period. A replacement number calculating function unit for calculating the number of replacements of the standard size tire;
Of the vehicles sold in the predetermined unit period, the standard size tire at the second time point from the number of vehicles remaining at the second time point and the replacement number calculated by the replacement number calculation function unit. A replacement number calculating function for calculating the replacement number of
A replacement total number calculation function unit that calculates the standard total replacement number in the predetermined period from the replacement number of the standard size tires calculated by the replacement number calculation function unit. Calculation device.   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 represents the distribution of the period of use of the standard size tire for the kth vehicle among the 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 according to the distribution function is expressed as H _L (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 type of vehicle sold for each predetermined unit period and the predicted value of the number of vehicles,
A period setting unit for setting the first time point and the second time point;
A size table acquisition unit for acquiring a size table in which a standard size that is a size of a tire mounted at the time of sale of the vehicle and the type of the vehicle is associated;
A change table acquisition unit that acquires a size change table in which the standard size and a change destination size that can be changed from the standard size are associated;
A change ratio setting unit for setting a predicted value of a change ratio to be changed from the standard size to the change destination size at the time of tire replacement;
A tire replacement total number calculating unit for calculating a standard replacement total number of the standard size tires to be replaced in a predetermined period between the first time point and the second time point in the vehicle;
A tire sales record acquisition unit for acquiring the number of sales of the standard size tires sold in the past;
The total number of modified replacements obtained by removing the number of changes calculated according to the predicted value of the change ratio set by the change ratio setting unit from the standard replacement total number calculated by the tire replacement total number calculating unit, and the tire sales By comparing the number of sales of the standard size tire acquired in the number of results acquisition unit, the predicted value of the change ratio when the total number of deformation replacements closest to the number of sales results is calculated is It functions as a ratio determination unit that determines the change ratio,
Further, the tire replacement total number calculating section is
In the vehicle remaining period set in the vehicle number setting unit according to the distribution function representing the distribution of the remaining ratio of the vehicle, the second time point is executed according to the distribution function representing the distribution of the tire usage period. A replacement number calculation function unit for calculating the number of replacements of the standard tire;
Of the vehicles sold in the predetermined unit period, the standard size tire at the second time point from the number of vehicles remaining at the second time point and the replacement number calculated by the replacement number calculation function unit. A replacement number calculating function for calculating the replacement number of
The replacement number calculating function unit functions as a replacement total number calculating function unit that calculates the standard replacement total number in the predetermined period from the replacement number of the tires of the standard size calculated by the replacement number calculating function unit. Tire demand calculation program.

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