Particle number measurement system, brake inspection system, and particle number measurement method

Abstract

The present invention reduces the cost for introducing a particle number measurement system, and reduces the difference between the uncertainty in measurement of the number of solid particles and the uncertainty in measurement of the total number of particles. The present invention comprises: a first diluter for diluting a sample gas; an evaporator for vaporizing volatile particles contained in the sample gas diluted by the first diluter; a second diluter for diluting the sample gas that has passed through the evaporator; a first particle number measurement device for measuring the number of particles contained in the sample gas diluted by the second diluter as the number of solid particles obtained by removing the volatile particles; and a second particle number measurement device for measuring the number of particles contained in the sample gas that has been diluted by the first diluter and is yet to pass through the evaporator as the total number of particles including the volatile particles.

Description

Particle number measurement system, brake inspection system, and particle number measurement method

[0001] The present invention relates to a particle number measurement system, a brake inspection system, and a particle number measurement method.

[0002] For example, the upcoming EU exhaust gas regulations (Euro 7) will regulate not only exhaust gas but also brake dust particles generated by braking. The regulations on brake dust particle count require the measurement of total particle count (TPN10), including volatile particles with a particle size larger than 10 nm, and solid particle count (SPN10), excluding volatile particles with a particle size larger than 10 nm.

[0003] In order to comply with this regulation, it is possible to prepare separate particle number measurement systems (TPN10 measurement system) for measuring the total particle number in the sample gas (TPN10) and for measuring the number of solid particles in the sample gas (SPN10 measurement system).

[0004] Here, as shown in Patent Document 1, the SPN10 measurement system must be provided with a volatile particle remover (VPR) for removing volatile particles from the sample gas. This volatile particle remover (VPR) has a heating diluter, an evaporator, and a cooling diluter. On the other hand, the TPN10 measurement system must dilute the sample gas, but must also measure the total number of particles including volatile particles, and therefore cannot use the volatile particle remover (VPR). Therefore, the TPN10 measurement system must use a diluter that is different from that used in the SPN10 measurement system.

[0005] However, it is necessary to prepare both a TPN10 measurement system and an SPN10 measurement system, which increases the system implementation cost. Furthermore, because the sample gas is diluted using different diluters, when comparing SPN10 and TPN10, there is a difference in measurement uncertainty due to the instrumental error of each diluter. As a result, when calculating the number of volatile particles from SPN10 and TPN10, the number of volatile particles cannot be accurately estimated.

[0006] Japanese Patent Application Laid-Open No. 2014-134555

[0007] Therefore, the present invention has been made in consideration of the above-mentioned problems, and its main object is to reduce the introduction cost of a particle number measurement system and to reduce the difference between the measurement uncertainty of the solid particle number and the measurement uncertainty of the total particle number.

[0008] That is, the particle number measurement system according to the present invention is a particle number measurement system that measures the number of particles contained in a sample gas, and is characterized by comprising: a main flow path through which the sample gas flows; a first diluter that is provided in the main flow path and dilutes the sample gas; an evaporator that is provided downstream of the first diluter and vaporizes volatile particles contained in the sample gas diluted by the first diluter; a second diluter that is provided downstream of the evaporator and dilutes the sample gas that has passed through the evaporator; and a particle number measurement unit that measures the number of particles contained in the sample gas diluted by the second diluter as the number of solid particles from which the volatile particles have been removed, and that measures the number of particles contained in the sample gas diluted by the first diluter and before it passes through the evaporator as the total number of particles including the volatile particles.

[0009] This particle number measurement system measures the number of solid particles contained in the sample gas diluted by the second diluter and the total number of particles contained in the sample gas diluted by the first diluter before passing through the evaporator, eliminating the need to prepare both a solid particle number measurement system and a total particle number measurement system as in the past, thereby reducing system implementation costs. Furthermore, because the same first diluter is used for measuring the solid particle number and the total particle number, the measurement uncertainty due to the instrumental error of the first diluter can be made the same, thereby reducing the difference between the measurement uncertainty of the solid particle number and the measurement uncertainty of the total particle number. Furthermore, the same sampling unit, such as a gas extractor that introduces sample gas into the main flow path, and its sampling position can be used for measuring the solid particle number and the total particle number, thereby reducing errors due to differences in the sampling unit and sampling position.

[0010] The particle number measurement unit preferably includes a first particle number measurement device that measures the number of solid particles and a second particle number measurement device that measures the total number of particles, the first particle number measurement device being provided in the main flow path downstream of the second diluter, and the second particle number measurement device being provided in a branch flow path that branches off from the main flow path between the first diluter and the evaporator. With this configuration, sample gas can be introduced simultaneously into both the first particle number measurement device and the second particle number measurement device. As a result, the number of solid particles from which volatile particles have been removed and the total number of particles including volatile particles can be measured simultaneously.

[0011] Furthermore, it is desirable that a bypass flow path that bypasses the evaporator and the second diluter is connected to the main flow path, and that the flow path through which the sample gas diluted by the first diluter flows can be switched between the evaporator side and the bypass flow path side, and that the particle number measurement unit be provided downstream of the bypass flow path in the main flow path. With this configuration, a common particle number measurement device is used instead of separate particle number measurement devices, thereby further reducing the cost of the particle number measurement system. In this configuration, when measuring the solid particle number, the particle number measurement unit receives sample gas from the main flow path via the first diluter, the evaporator, and the second diluter, and when measuring the total particle number, the sample gas is received from the bypass flow path via the first diluter.

[0012] In order to suitably measure the number of brake dust particles that have been introduced into recent exhaust gas regulations, it is desirable that the particles contained in the sample gas are brake dust generated when the brakes are applied, and that the particle number measuring unit measures the number of solid particles in the brake dust excluding volatile particles, and also measures the total number of particles in the brake dust including volatile particles.

[0013] In order to improve user convenience in particle number measurement, it is desirable that the particle number measurement system of the present invention include a calculation device that calculates a solid particle number concentration from the count data of the solid particle number and calculates a total particle number concentration from the count data of the total particle number.

[0014] It is desirable that the calculation device further include a volatile particle calculation unit that calculates the number of volatile particles by subtracting the number of solid particles from the first particle number measurement device from the total particle number from the second particle number measurement device. Furthermore, in the present invention, since the measurement uncertainty due to the instrumental error of the first diluter is shared, the number of volatile particles obtained by subtracting the number of solid particles from the total particle number can be accurately estimated.

[0015] When the sample gas flows through each of the first diluter, the second diluter, and the evaporator, particles contained in the sample gas may adhere to the interior of these devices and be lost, making it impossible to measure the number of particles accurately. To solve this problem, it is preferable that the calculation device further includes a particle number correction unit that corrects the number of solid particles in the first particle number measurement device using the particle loss coefficients of the first diluter, the second diluter, and the evaporator, respectively, and corrects the total number of particles in the second particle number measurement device using the particle loss coefficient of the first diluter.

[0016] For example, if a second particle number measurement device is provided by branching a branch flow path from the main flow path, the arrival time of the sample gas from the branch point to the first particle number measurement device may differ from the arrival time of the sample gas from the branch point to the second particle number measurement device. In this case, the first particle number measurement device and the second particle number measurement device will measure the particle numbers of the sample gas at different times. In other words, there is a time difference between the solid particle number and total particle number obtained at the same measurement time. To resolve this problem, it is preferable that the calculation device further include a response correction unit that corrects the difference between the response delay time of the first particle number measurement device and the response delay time of the second particle number measurement device.

[0017] In a specific embodiment of the vaporizer, the vaporizer may heat the sample gas to 350° C. or more, which can reliably vaporize and remove volatile particles such as brake dust from the sample gas.

[0018] As a specific embodiment of the first diluter and the second diluter, the first diluter may dilute the sample gas in a range of 10 to 200 times, and the second diluter may dilute the sample gas that has passed through the evaporator in a range of 10 to 20 times.

[0019] In addition, the brake inspection system of the present invention is characterized by comprising a test system that operates the brakes in a predetermined test cycle, a collection system that collects brake dust generated by the test system, and the above-mentioned particle number measurement system that measures the number of particles contained in a sample gas containing the brake dust collected by the collection system.

[0020] Furthermore, the particle number measurement method according to the present invention preferably includes the steps of: diluting a sample gas using a first diluter; vaporizing volatile particles contained in the sample gas diluted by the first diluter using an evaporator; diluting the sample gas that has passed through the evaporator using a second diluter; measuring the number of particles contained in the sample gas diluted by the second diluter as the number of solid particles from which the volatile particles have been removed; and measuring the number of particles contained in the sample gas diluted by the first diluter and before it passes through the evaporator as the total number of particles including the volatile particles.

[0021] According to the present invention as described above, it is possible to reduce the cost of introducing a particle number measurement system and to reduce the difference between the uncertainty in measuring the number of solid particles and the uncertainty in measuring the total number of particles.

[0022] It is an overall schematic diagram of a particle number measurement system according to one embodiment of the present invention. It is a functional configuration diagram of a calculation device of the same embodiment. It is a schematic diagram of a brake inspection system using the particle number measurement system of the same embodiment. It is an overall schematic diagram of a particle number measurement system according to a modified embodiment.

[0023] <One embodiment of the present invention> Hereinafter, one embodiment of a particle number measurement system according to the present invention will be described with reference to the drawings. Note that in all of the drawings shown below, parts are appropriately omitted or exaggerated for ease of understanding. Identical components are assigned the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0024] <Basic Configuration of Particle Number Measurement System 100> The particle number measurement system 100 of this embodiment measures the number of particles contained in a sample gas, and measures the number of brake dust particles generated when the brakes are applied. This particle number measurement system 100 measures the number of solid particles from which volatile particles have been removed and the total number of particles including volatile particles in flake dust. The solid particle number is, for example, the solid particle number (SPN10) excluding volatile particles with a particle diameter larger than 10 nm, and the total particle number is, for example, the total particle number (TPN10) including volatile particles with a particle diameter larger than 10 nm. Note that the particle diameter used to distinguish between the solid particle number and the volatile particles is not limited to 10 nm and may be other particle diameters.

[0025] 1 , the particle number measurement system 100 includes a main flow path ML through which sample gas containing brake dust flows, a first diluter 2 provided in the main flow path ML and diluting the sample gas, an evaporator 3 provided downstream of the first diluter 2 and vaporizing volatile particles contained in the sample gas diluted by the first diluter 2, a second diluter 4 provided downstream of the evaporator 3 and diluting the sample gas that has passed through the evaporator 3, a first particle number measurement device 5 that measures the number of particles contained in the sample gas diluted by the second diluter 4, and a second particle number measurement device 6 that measures the number of particles contained in the sample gas diluted by the first diluter 2 and before it passes through the evaporator 3. The first particle number measurement device 5 and the second particle number measurement device 6 of this embodiment constitute a particle number measurement unit X.

[0026] The first diluter 2 dilutes the sample gas by mixing it with a dilution gas. The first diluter 2 is used at room temperature, for example, at 40°C or below, preferably in the temperature range of 5 to 35°C. A first dilution gas inlet passage DL1 for introducing a dilution gas is connected to the first diluter 2 or the main flow path ML upstream of the first diluter 2. Note that the dilution gas may be, for example, air that has been passed through a filter.

[0027] The first diluter 2 dilutes the sample gas, for example, in the range of 10 to 200 times. This dilution ratio is adjusted, for example, by measuring the flow rate of the sample gas with a flow rate measuring mechanism 7 provided upstream of the first diluter 2 and adjusting the flow rate of the diluted gas with a flow rate adjusting mechanism 8 provided in the first diluted gas inlet line DL1.

[0028] The evaporator 3 is provided downstream of the first diluter 2 in the main flow path ML, and vaporizes volatile particles contained in the sample gas diluted by the first diluter 2. The evaporator 3 is configured to heat the sample gas to 350°C or higher to vaporize the volatile particles. The evaporator 3 also has an oxidation catalyst function.

[0029] The second diluter 4 is provided downstream of the evaporator 3 in the main flow path ML, and dilutes the sample gas by mixing a dilution gas with the sample gas that has passed through the evaporator 3. The second diluter 4 is used at room temperature, for example, at 40°C or below, preferably in a temperature range of 5 to 35°C. A second dilution gas inlet line DL2 for introducing a dilution gas is connected between the evaporator 3 and the second diluter 4 in the second diluter 4 or the main flow path ML. The dilution gas may be, for example, air that has been passed through a filter.

[0030] The second diluter 4 dilutes the sample gas, for example, in the range of 10 to 20 times. Alternatively, the second diluter 4 may dilute the sample gas at a constant dilution ratio, for example, 15 times. This dilution ratio is adjusted, for example, by using the flow rate measured by the flow rate measuring mechanism 7 to adjust the flow rate of the diluted gas by the flow rate adjusting mechanism 9 provided in the second diluted gas inlet path DL2.

[0031] The first particle number measuring device 5 measures the number of particles contained in the sample gas diluted by the second diluter 4 as the number of solid particles from which volatile particles have been removed. The first particle number measuring device 5 is provided downstream of the second diluter 4 in the main flow path ML.

[0032] Specifically, the first particle number measuring device 5 mixes an organic gas such as alcohol or butanol in a supersaturated state and causes it to adhere to particles in the sample gas, thereby causing the particles to grow to a large diameter, and then discharges the grown particles through a slit and counts the emitted particles with a laser beam. The count data of the number of solid particles measured by the first particle number measuring device 5 is output to the calculation device 10 and processed appropriately to calculate the particle number concentration of the number of solid particles, etc.

[0033] The second particle number measuring device 6 measures the number of particles contained in the sample gas diluted by the first diluter 2 and before passing through the evaporator 3 as the total number of particles including volatile particles. The second particle number measuring device 6 of this embodiment is provided in a branch flow path BL that branches off from the main flow path ML between the first diluter 2 and the evaporator 3.

[0034] Specifically, the second particle number measuring device 6, like the first particle number measuring device 5, mixes an organic gas such as alcohol or butanol in a supersaturated state and causes it to adhere to particles in the sample gas, thereby causing the particles to grow to a large diameter, and then discharges the grown particles through a slit and counts the emitted particles with laser light. The count data of the total particle number measured by the second particle number measuring device 6 is output to the calculation device 10 and processed appropriately to calculate the particle number concentration of the total particle number, etc.

[0035] The arithmetic device 10 of this embodiment is a so-called general-purpose or dedicated computer equipped with a CPU, memory, input means, display, etc., in which the CPU and peripheral devices cooperate to operate in accordance with a predetermined program stored in the memory. The arithmetic device 10 calculates a solid particle number concentration from count data of the solid particle number and calculates a total particle number concentration from count data of the total particle number. Specifically, the arithmetic device 10 includes a solid particle number calculation unit 10a that calculates a solid particle number concentration, etc. from count data of the solid particle number measured by the first particle number measurement device 5, and a total particle number calculation unit 10b that calculates a total particle number concentration, etc. from count data of the total particle number measured by the second particle number measurement device 6. The arithmetic device 10 may further include a nonvolatile particle calculation unit 10c that calculates a volatile particle number by subtracting the solid particle number from the total particle number calculated by each of the calculation units 10a and 10b.

[0036] Furthermore, the calculation device 10 may further include a particle number correction unit 10d that corrects the number of solid particles obtained by the first particle number measuring device 5 using the total particle loss coefficient of the first diluter 2, the second diluter 4, and the evaporator 3, and corrects the total particle number obtained by the second particle number measuring device 6 using the particle loss coefficient of the first diluter 2.

[0037] Here, the particle loss coefficients of the first diluter 2, the second diluter 4, and the evaporator 3 used in the particle number correction unit 10d can be calculated, for example, as follows.

[0038] A first standard gas inlet line SL1 for introducing a standard gas having a known particle number concentration is connected to the main flow path ML upstream of the flow rate measurement mechanism. Also, a second standard gas inlet line SL2 for introducing a standard gas having a known particle number concentration is connected to the main flow path ML between the second diluter 4 and the first particle number measurement device 5. Furthermore, a second standard gas inlet line SL2 for introducing a standard gas having a known particle number concentration is connected to the branch flow path BL upstream of the second particle number measurement device 6.

[0039] Then, a gas having a known particle number concentration (concentration C ０) is introduced into the atmosphere, and the number of particles is measured by the first particle number measuring device 5 and the second particle number measuring device 6. The calculation device 10 calculates a first particle number concentration C １ and calculates the second particle number concentration C from the count data of the second particle number measuring device 6. ２ Calculate the following.

[0040] Next, a gas having a known particle number concentration (concentration C ０ ) is introduced, and the number of particles in the standard gas is measured by the first particle number measuring device 5. The calculation device 10 calculates a first particle number concentration C １ The calculation device 10 calculates the first particle number concentration C １ and the first particle number concentration C １ Based on the above, the total particle loss coefficient of the first diluter 2, the second diluter 4 and the evaporator 3 is calculated.

[0041] Next, a gas having a known particle number concentration (concentration C ０ ) is introduced, and the number of particles in the standard gas is measured by the second particle number measuring device 6. The calculation device 10 calculates a second particle number concentration C ２ The calculation device 10 calculates the second particle number concentration C ２ and second particle number concentration C ２ ', the particle loss coefficient of the first diluter 2 is calculated.

[0042] Furthermore, the arithmetic device 10 of this embodiment may further include a response correction unit 10e that corrects the difference between the response delay time of the first particle number measurement device 5 and the response delay time of the second particle number measurement device 6. This response correction unit 10e corrects the difference between a first arrival time, which is the time it takes for the sample gas introduced into the main flow path ML to reach the first particle number measurement device 5, and a second arrival time, which is the time before the sample gas introduced into the main flow path ML reaches the second particle number measurement device 6. These first arrival time and second arrival time can be obtained, for example, by introducing a standard gas or the like with a known particle number concentration into the main flow path ML and then measuring the rise time of the signal from the first particle number measurement device 5 and the rise time of the signal from the second particle number measurement device 6.

[0043] <Effects of this embodiment> The particle number measurement system 100 of this embodiment configured as described above includes the first particle number measurement device 5 that measures the number of solid particles contained in the sample gas diluted by the second diluter 4, and the second particle number measurement device 6 that measures the total number of particles contained in the sample gas diluted by the first diluter 2 and before passing through the evaporator 3. This eliminates the need to prepare both a measurement system for the number of solid particles and a measurement system for the total particle number, as in the conventional system, thereby reducing the introduction cost of the system. Furthermore, because the first particle number measurement device 5 that measures the number of solid particles and the second particle number measurement device 6 that measures the number of total particles share the same first diluter 2, the measurement uncertainty due to the instrument error of the first diluter 2 can be shared, and the difference between the measurement uncertainty of the solid particle number and the measurement uncertainty of the total particle number can be reduced. Furthermore, the sampling unit, such as a gas collection unit that introduces sample gas into the main flow path ML, and its sampling position can be made common between the first particle number measuring device 5 that measures the number of solid particles and the second particle number measuring device 6 that measures the total number of particles, so it is expected that errors due to differences in the sampling unit and sampling position will be reduced.

[0044] 3 , the brake inspection system includes a test system 200 that operates the brakes in a predetermined test cycle, a collection system 300 that collects brake dust generated by the test system 200, and the particle number measurement system 100 of the above embodiment that measures the number of particles contained in a sample gas containing the brake dust collected by the collection system 300.

[0045] The test system 200 includes a housing 201 that accommodates the brakes BK and a brake dynamo 202 that applies a load to the brakes BK inside the housing 201. The brake dynamo 202 operates the brakes BK in a predetermined test cycle. The collection system 300 also includes an exhaust flow path 301 that exhausts brake dust generated inside the housing 201 together with air. The particle number measurement system 100 samples the air flowing through the exhaust flow path 301 and introduces it as sample gas into the main flow path ML.

[0046] In the above embodiment, the second particle number measurement device 6 is provided in the branch flow path BL. However, as shown in FIG. 4 , a bypass flow path BL1 that bypasses the evaporator 3 and the second diluter 4 may be connected to the main flow path ML, and a common particle number measurement device 11 serving as the particle number measurement unit X may be provided downstream of the bypass flow path BL1 in the main flow path ML. In this case, the flow path through which the sample gas diluted by the first diluter 2 flows may be configured to be switchable between the evaporator 3 side and the bypass flow path BL1 side. Specifically, a switching mechanism 12 that switches between the evaporator 3 side and the bypass flow path BL1 side may be provided. This switching mechanism 12 may be configured with an on-off valve 12a provided between the branch point of the bypass flow path BL1 and the evaporator 3, and an on-off valve 12b provided in the bypass flow path BL1. Alternatively, the switching mechanism 12 may be a three-way valve provided at the branch point of the bypass flow path BL1 that switches between the evaporator 3 side and the bypass flow path BL1 side. In this configuration, when measuring the number of solid particles in the particle number measurement unit X, sample gas is introduced from the main flow path ML via the first diluter 2, the evaporator 3, and the second diluter 4, and when measuring the total number of particles, sample gas is introduced from the bypass flow path BL1 via the first diluter 2.

[0047] In addition to the above embodiment, another analyzer may be connected to the branch flow path BL. Here, the other analyzer may be one other than the particle number measuring device.

[0048] Although the above embodiment measures the number of brake dust particles contained in the sample gas, it may also be possible to measure the number of particles contained in exhaust gas or the atmosphere.

[0049] Although the particle number measurement system 100 of the above embodiment is configured to include the arithmetic device 10, it may be configured not to include the arithmetic device 10. In this case, it is conceivable to configure the particle number measurement unit X of the particle number measurement system 100 to output the count data of the solid particle number and the count data of the total particle number to an external information processing device.

[0050] In addition, various modifications and combinations of the embodiments may be made as long as they do not go against the spirit of the present invention.

[0051] According to the present invention, it is possible to reduce the cost of introducing a particle number measurement system and to reduce the difference between the uncertainty in measuring the number of solid particles and the uncertainty in measuring the total number of particles.

[0052] REFERENCE SIGNS LIST 100 Particle number measurement system 200 Test system 300 Collection system ML Main flow path BL Bypass flow path 2 First diluter 3 Evaporator 4 Second diluter X Particle number measurement section 5 First particle number measurement device 6 Second particle number measurement device 10 Calculation device 10c Calculation section 10d Particle number correction section 10e Response correction section

Claims

1. A particle number measurement system for measuring the number of particles contained in a sample gas, comprising: a main flow path through which the sample gas flows; a first diluter provided in the main flow path for diluting the sample gas; an evaporator provided downstream of the first diluter for vaporizing volatile particles contained in the sample gas diluted by the first diluter; a second diluter provided downstream of the evaporator for diluting the sample gas that has passed through the evaporator; and a particle number measurement unit that measures the number of particles contained in the sample gas diluted by the second diluter as the number of solid particles from which the volatile particles have been removed, and that measures the number of particles contained in the sample gas diluted by the first diluter and before it passes through the evaporator as the total number of particles including the volatile particles.

2. The particle number measurement system according to claim 1, wherein the particle number measurement unit comprises a first particle number measurement device that measures the number of solid particles, and a second particle number measurement device that measures the total number of particles, the first particle number measurement device being provided in the main flow path downstream of the second diluter, and the second particle number measurement device being provided in a branch flow path that branches off from between the first diluter and the evaporator in the main flow path.

3. A particle number measurement system as described in claim 1, wherein a bypass flow path that bypasses the evaporator and the second diluter is connected to the main flow path, the flow path through which the sample gas diluted by the first diluter flows is switchable to either the evaporator side or the bypass flow path side, and the particle number measurement unit is provided in the main flow path downstream of the bypass flow path.

4. The particle number measuring system according to claim 3, wherein the particle number measuring unit introduces a sample gas from the main flow path via the first diluter, the evaporator, and the second diluter when measuring the number of solid particles, and introduces a sample gas from the bypass flow path via the first diluter when measuring the total particle number.

5. A particle number measurement system as described in any one of claims 1 to 4, wherein the particles contained in the sample gas are brake dust generated when the brakes are applied, and the particle number measurement unit measures the number of solid particles in the brake dust excluding volatile particles, and measures the total number of particles in the brake dust including volatile particles.

6. A particle number measuring system according to any one of claims 1 to 5, further comprising a calculation device that calculates a solid particle number concentration from the count data of the solid particle number, and calculates a total particle number concentration from the count data of the total particle number.

7. The particle number measuring system according to claim 6, wherein the calculation device further comprises a volatile particle calculation unit that calculates the number of volatile particles by subtracting the number of solid particles from the total number of particles.

8. The particle number measurement system according to claim 6 or 7, further comprising a particle number correction unit, wherein the calculation device corrects the solid particle number using the particle loss coefficients of the first diluter, the second diluter and the evaporator, and corrects the total particle number using the particle loss coefficient of the first diluter.

9. A particle number measurement system as described in claim 6 or 7 which cites claim 2, wherein the calculation device further includes a response correction unit which corrects the difference between the response delay time of the first particle number measurement device and the response delay time of the second particle number measurement device.

10. A particle number measurement system according to any one of claims 1 to 9, wherein the evaporator heats the sample gas to 350 degrees or higher.

11. A particle number measurement system according to any one of claims 1 to 10, wherein the first diluter dilutes the sample gas in a range of 10 to 200 times, and the second diluter dilutes the sample gas that has passed through the evaporator in a range of 10 to 20 times.

12. A brake inspection system comprising: a test system that operates a brake in a predetermined test cycle; a collection system that collects brake dust generated by the test system; and a particle number measurement system according to any one of claims 1 to 11 that measures the number of particles contained in a sample gas containing the brake dust collected by the collection system.

13. A particle number measurement method comprising: diluting a sample gas using a first diluter; vaporizing volatile particles contained in the sample gas diluted by the first diluter using an evaporator; diluting the sample gas that has passed through the evaporator using a second diluter; measuring the number of particles contained in the sample gas diluted by the second diluter as the number of solid particles from which the volatile particles have been removed; and measuring the number of particles contained in the sample gas diluted by the first diluter and before it passes through the evaporator as the total number of particles including the volatile particles.

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