Braking state estimation device, vehicle equipped with the same, braking state estimation method, and computer-readable recording medium

Abstract

The present disclosure relates to a brake state estimation device, a vehicle provided with the brake state estimation device, a brake state estimation method, and a program. The brake state estimation device includes a position acquisition unit that acquires a position of a target vehicle, and a state estimation unit that estimates a deterioration state of brake fluid for operating a hydraulic brake device of the target vehicle on the basis of humidity information corresponding to the position of the target vehicle and period information indicating a period during which the target vehicle stays in a region including the position of the target vehicle.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a brake state estimation device, a vehicle equipped with the brake state estimation device, a brake state estimation method, and a program. BACKGROUND

[0002] A brake device monitoring system is disclosed in Japanese Patent Application Publication No. 2019-119401, which includes a sensor embedded in a banjo bolt used when connecting a brake hose to a brake caliper, and a reporting unit that reports a parameter indicating a state of brake fluid generated based on a sensor signal sensed by the sensor to a driver.

[0003] In the technology described in Japanese Patent Application Publication No. 2019-119401, in order to detect the state of the brake fluid, a sensor needs to be separately installed. SUMMARY

[0004] In view of the above, an object of the present disclosure is to estimate the deterioration state of brake fluid by a simple configuration.

[0005] The first aspect is a brake state estimation device including a position acquisition unit that acquires a position of a target vehicle, and a state estimation unit that estimates a deterioration state of brake fluid used to operate a hydraulic brake device of the target vehicle based on humidity information corresponding to the position of the target vehicle and period information indicating a period during which a region including the position of the target vehicle is stayed.

[0006] In the brake state estimation device of the first aspect, the position acquisition unit acquires the position of the target vehicle. Then, the state estimation unit estimates the deterioration state of the brake fluid used to operate the hydraulic brake device of the target vehicle based on the humidity information corresponding to the position of the target vehicle and the period information indicating the period during which the region including the position of the target vehicle is stayed. Here, the "humidity information" refers to information associated with humidity at the position of the target vehicle, and refers to information related to the amount of moisture contained in the brake fluid of the target vehicle. In addition, the "deterioration state of the brake fluid" refers to a state associated with the occurrence of vapor lock of the brake fluid. According to this brake state estimation device, the deterioration state of the brake fluid can be estimated by a simple configuration.

[0007] For the brake state estimation device of the second aspect, in the brake state estimation device of the first aspect, a temperature acquisition unit that acquires a temperature of the brake device is further included, and the state estimation unit estimates the deterioration state of the brake fluid based on the temperature of the brake device, the humidity information, and the period information.

[0008] The brake state estimation device of the second aspect further acquires a temperature of the brake device, and estimates the deterioration state of the brake fluid based on the temperature of the brake device, the humidity information, and the period information. According to the brake state estimation device, the deterioration state of the brake fluid can be estimated with high accuracy.

[0009] The brake state estimation device of the third aspect is the brake state estimation device of the second aspect in which the state estimation section estimates a moisture state contained in the brake fluid based on the humidity information and the period information, estimates a thermal state of the brake fluid based on the temperature of the brake device, and estimates the deterioration state of the brake fluid based on the moisture state and the thermal state.

[0010] The brake state estimation device of the third aspect estimates a moisture state contained in the brake fluid based on the humidity information and the period information, estimates a thermal state of the brake fluid based on the temperature of the brake device, and estimates the deterioration state of the brake fluid based on the moisture state and the thermal state. According to the brake state estimation device, the deterioration state of the brake fluid can be estimated with high accuracy while taking into account the moisture state and the thermal state of the brake fluid.

[0011] The brake state estimation device of the fourth aspect is the brake state estimation device of the second aspect in which the state estimation section estimates the deterioration state using a learned model for estimating the deterioration state of the brake fluid based on the temperature of the brake device, the humidity information, and the period information.

[0012] The brake state estimation device of the fourth aspect estimates the deterioration state using a learned model for estimating the deterioration state of the brake fluid based on the temperature of the brake device, the humidity information, and the period information. According to the brake state estimation device, the deterioration state of the brake fluid can be estimated with high accuracy.

[0013] The vehicle of the fifth aspect includes the brake state estimation device of any one of the first to fourth aspects, and the hydraulic brake device.

[0014] The vehicle of the fifth aspect includes the hydraulic brake device, and estimates the deterioration state of the brake fluid of the hydraulic brake device. According to the vehicle, the deterioration state of the brake fluid can be estimated with a simple configuration.

[0015] In the brake state estimation method according to the sixth aspect, a position acquisition unit acquires a position of an object vehicle, and a state estimation unit estimates a deterioration state of brake fluid for operating a hydraulic brake device of the object vehicle on the basis of humidity information corresponding to the position of the object vehicle and period information indicating a period during which a region including the position of the object vehicle is stayed.

[0016] The sixth aspect is a brake state estimation method in which a position acquisition unit acquires a position of an object vehicle. Then, a state estimation unit estimates a deterioration state of brake fluid for operating a hydraulic brake device of the object vehicle on the basis of humidity information corresponding to the position of the object vehicle and period information indicating a period during which a region including the position of the object vehicle is stayed. According to this brake state estimation method, the deterioration state of the brake fluid can be estimated with a simple configuration.

[0017] The seventh aspect is a non-transitory recording medium that records a program for causing a computer to execute: acquiring a position of an object vehicle, and estimating a deterioration state of brake fluid for operating a hydraulic brake device of the object vehicle on the basis of humidity information corresponding to the position of the object vehicle and period information indicating a period during which a region including the position of the object vehicle is stayed.

[0018] In the program recorded in the non-transitory recording medium according to the seventh aspect, a computer acquires a position of an object vehicle. Then, the computer estimates a deterioration state of brake fluid for operating a hydraulic brake device of the object vehicle on the basis of humidity information corresponding to the position of the object vehicle and period information indicating a period during which a region including the position of the object vehicle is stayed. According to this program, the deterioration state of the brake fluid can be estimated with a simple configuration.

[0019] Effects of Invention

[0020] According to the present disclosure, the deterioration state of the brake fluid can be estimated with a simple configuration. BRIEF DESCRIPTION OF DRAWINGS

[0021] Hereinafter, exemplary embodiments of the present disclosure are described in detail based on the drawings, in which:

[0022] Figure 1 is a diagram showing an outline configuration of a vehicle system according to the first embodiment, the second embodiment, and the third embodiment;

[0023] Figure 2 is an outline diagram showing a configuration of a brake device of a vehicle according to the first embodiment, the second embodiment, and the third embodiment;

[0024] Figure 3is a block diagram showing the hardware configuration of the vehicle of the first embodiment, the second embodiment, the third embodiment;

[0025] Figure 4 is a block diagram showing an example of the functional configuration of the CPU of the control ECU in the vehicle-mounted device of the first embodiment, the second embodiment;

[0026] Figure 5 is a graph showing the relationship between the moisture amount and the period in each region;

[0027] Figure 6 is a graph showing the relationship between the moisture amount and the period in the case where the vehicle stays in a plurality of regions;

[0028] Figure 7 is a display example of the estimation result of the deterioration state of the brake fluid;

[0029] Figure 8 is a flowchart showing one example of the flow of the brake state estimation process executed in the CPU of the control ECU in the vehicle-mounted device of the first embodiment;

[0030] Figure 9 is a flowchart showing one example of the flow of the brake state estimation process executed in the CPU of the control ECU in the vehicle-mounted device of the second embodiment;

[0031] Figure 10 is a block diagram showing the hardware configuration of the management server of the third embodiment;

[0032] Figure 11 is a block diagram showing an example of the functional configuration of the CPU of the control device in the management server of the third embodiment. DETAILED DESCRIPTION

[0033] The vehicle system of the embodiment of the present disclosure will be described using Figures 1-11

[0034] [First Embodiment]

[0035] Figure 1 is a block diagram showing the outline configuration of the vehicle system 10 of the first embodiment.

[0036] (Overall Configuration)

[0037] As shown in Figure 1 , the vehicle system 10 of the embodiment includes a vehicle 12 and a management server 16.

[0038] ​Vehicle 12 and management server 16 are configured to communicate via network N. Vehicle 12 includes a communication unit 14 connected to network N. Network N includes mobile communication services such as 3G and LTE (Long Term Evolution) and internet access.

[0039] (vehicle)

[0040] Vehicle 12 is equipped with a hydraulic braking system 18. For example... Figure 2 As shown, the braking device 18 is configured to include: a brake pedal 40, located in the driver's seat and operated by the driver; a brake booster 42, which increases the force applied to the brake pedal 40; a master cylinder 44, integrally mounted on the brake booster 42, which generates hydraulic pressure of brake fluid 48 corresponding to the force applied to the brake pedal 40; brake hoses 46, connecting the master cylinder 44 to the braking mechanisms (e.g., brake discs) of each wheel; a reserve tank 50, located above the master cylinder 44, which stores brake fluid 48 by injecting it into and always filling the brake hoses 46; and a hydraulic sensor 52, which detects the hydraulic pressure of brake fluid 48 in the brake hoses 46. It should be noted that the hydraulic sensor 52 can also be located on a brake actuator used for braking control, such as ABS (Antilock Braking System) (not shown).

[0041] like Figure 3 As shown, the on-board unit 11 mounted on the vehicle 12 includes a control ECU (Electronic Control Unit) 20, a temperature sensor 22, a vehicle speed sensor 24, a hybrid power ECU 26, and a communication unit 14.

[0042] Temperature sensor 22 detects the ambient temperature of vehicle 12. Vehicle speed sensor 24 detects the vehicle speed of vehicle 12. Hybrid ECU 26 determines the driving mode (engine driving mode, motor driving mode, etc.), determines the engine torque and motor torque based on signals from various sensors including accelerator opening sensor (not shown), vehicle speed sensor 24, etc., and issues commands to engine ECU (not shown) and motor ECU (not shown). In addition, hybrid ECU 26 detects the regenerative capacity of the motor.

[0043] The control ECU 20 is configured to include a CPU (Central Processing Unit) 20A, a ROM (Read Only Memory) 20B, a RAM (Random Access Memory) 20C, an external storage 20D, and an input-output I / F (Inter Face) 20E. The CPU 20A, the ROM 20B, the RAM 20C, and the input-output I / F 20E are connected to be able to communicate with each other via an internal bus not shown. The CPU 20A is one example of a processor, and the RAM 20C is one example of a memory.

[0044] The CPU 20A is a central arithmetic processing unit that executes various programs or controls each part. That is, the CPU 20A reads out a program from the ROM 20B and executes the program using the RAM 20C as a work area.

[0045] The ROM 20B stores various programs and various data. The RAM 20C temporarily stores a program or data as a work area.

[0046] The external storage 20D stores a brake state estimation program 100. The external storage 20D is constituted by, for example, a HDD (Hard Disk Drive) or a SSD (Solid State Drive).

[0047] The input-output I / F 20E is an interface for communicating with the brake device 18, the temperature sensor 22, the vehicle speed sensor 24, the hybrid ECU 26, and the communication section 14, respectively.

[0048] With regard to the brake fluid, there is a problem that the stopping distance increases due to a phenomenon called air resistance. There is an influence between the air resistance and the boiling point of the brake fluid, and the amount of moisture, which is a factor for lowering the boiling point of the brake fluid, is determined by the total heat load, the period, and the humidity.

[0049] The existing system is a mechanism in which the sensor located at the reservoir tank detects when the brake fluid leaks. Although the amount of the brake fluid as a whole is detected by the sensor, it is not possible to objectively or quantitatively determine how much moisture amount the brake fluid itself contains and further determine the deterioration state.

[0050] Even if the automobile manufacturer sets the replacement period to be every two years at the time of vehicle inspection, the replacement period of the brake fluid is not necessarily uniform because it depends on the running condition of the vehicle. For example, depending on the contamination and the deterioration state of the brake fluid, the replacement period sometimes becomes early or late. Ultimately, the replacement period of the brake fluid of the automobile manufacturers in Japan is basically uniformly recommended to be replaced at the time of vehicle inspection each time.

[0051] From the perspective of users undergoing vehicle inspections, there is a tendency to consider controlling inspection costs if the brake fluid appears clean. However, in reality, there are also vehicles that have undergone inspections at private shops without having their brake fluid replaced.

[0052] Thus, the brake lines filled with brake fluid are sealed off. Therefore, existing methods for judging the deterioration state of brake fluid rely on the amount in the reservoir and the color of the brake fluid. Immediately after a brake fluid change, it is almost transparent, but as it deteriorates, it changes in the order of transparent, yellow, brown, and black. In many vehicles, the brake fluid is yellow, making it impossible to judge its deterioration state based on color alone.

[0053] Therefore, in this embodiment, the vehicle-mounted device 11 effectively utilizes vehicle driving data to predict the deterioration state of the driving fluid.

[0054] Specifically, such as Figure 4 As shown, in the control ECU20 of this embodiment, the CPU20A executes the braking state estimation program 100, thereby functioning as the position acquisition unit 30, the information acquisition unit 32, the temperature acquisition unit 34, and the state estimation unit 36.

[0055] The location acquisition unit 30 acquires the location of the vehicle 12. For example, the location acquisition unit 30 acquires the latitude and longitude of the vehicle 12's location from a navigation system installed in the vehicle 12.

[0056] The information acquisition unit 32 acquires period information indicating the duration of stay in the area including the vehicle's location, based on the location of the vehicle 12 acquired by the location acquisition unit 30. Furthermore, the information acquisition unit 32 acquires humidity information based on the location of the vehicle 12 acquired by the location acquisition unit 30. For example, the information acquisition unit 32 sends the location of the vehicle 12 acquired by the location acquisition unit 30 to the management server 16 via the communication unit 14, and acquires from the management server 16 a coefficient, pre-calculated for the area including the vehicle 12's location, representing the relationship between the amount of water in the brake fluid and the duration, as humidity information corresponding to the location of the vehicle 12.

[0057] The temperature acquisition unit 34 acquires the temperature of the braking device 18. Specifically, the temperature acquisition unit 34 calculates the temperature of the braking device 18 based on the air temperature detected by the temperature sensor 22, the vehicle speed detected by the vehicle speed sensor 24, the hydraulic pressure of the brake fluid 48 detected by the hydraulic pressure sensor 52 of the braking device 18, and the regeneration amount detected by the hybrid ECU 26.

[0058] For example, the temperature acquisition unit 34 acquires the air temperature detected by the temperature sensor 22, the vehicle speed detected by the vehicle speed sensor 24, the hydraulic pressure of the brake fluid 48 detected by the hydraulic sensor 52 of the brake device 18, and the amount of regeneration detected by the hybrid ECU 26 every prescribed time, and accumulates the change amount ΔT of the temperature of the brake disc over Δt seconds in accordance with the following (1) formula and (2) formula, thereby calculating the temperature T of the brake disc R .

[0059]

[0060] T R = T before + ΔT (2)

[0061] where Q in is the brake absorbed energy, Q out is the brake dissipated energy, W b is the weight of the sliding portion of the brake disc, C is the specific heat, T before is the temperature of the brake disc before Δt seconds. Further, Δt is the sampling period.

[0062] The brake absorbed energy Q in at the time of braking is represented by the following formula.

[0063]

[0064] where P is the hydraulic pressure of the brake fluid 48, A b is the area of the sliding portion of the brake disc, μ is the friction coefficient of the pad, and R is the effective radius of braking (the distance between the center of the tire and the center of the caliper piston).

[0065] Further, outside the time of braking, in the case where the regenerative braking is not taken into account, the brake absorbed energy Q in is represented by the following formula.

[0066]

[0067] where M is the weight of the vehicle 12, V is the vehicle speed, V before is the vehicle speed before Δt seconds, α is the brake force distribution, C1 is the running resistance loss coefficient, and C2 is the heat loss coefficient other than the sliding portion of the brake disc.

[0068] Further, outside the time of braking, in the case where the regenerative braking is taken into account, the brake absorbed energy Q in is represented by the following formula.

[0069]

[0070] where W in is the amount of regeneration.

[0071] In addition, the brake heat dissipation energy Q out is expressed by the following equation.

[0072] Q out = h V * A b * (T before - T atm ) * Δt

[0073] where h V is a heat transfer coefficient, T atm is the air temperature detected by the temperature sensor 22.

[0074] The state estimation section 36 estimates the deterioration state of the brake fluid 48 based on the humidity information, the period information indicating the period during which the vehicle stays in the area including the position of the vehicle, and the temperature of the brake device 18.

[0075] Specifically, the state estimation section 36 estimates the moisture state contained in the brake fluid 48 based on the humidity information and the period information, estimates the thermal state of the brake fluid 48 based on the temperature of the brake device 18, and estimates the deterioration state of the brake fluid 48 based on the moisture state and the thermal state.

[0076] For example, every time the temperature of the brake disc exceeds a threshold temperature, the value of the thermal state indicating the deterioration state of the brake fluid 48 caused by heat is incremented by 1, and it is estimated that there is a possibility that the air resistance occurs. The threshold temperature can be set to a temperature at which the effectiveness of the braking decreases.

[0077] In addition, the management server 16 stores, in advance, as the humidity information, a coefficient indicating the relationship between the amount of moisture contained in the brake fluid and the period for each area prepared in advance using big data. In particular, it is known that the relationship between the amount of moisture contained in the brake fluid and the period differs between an area with high humidity and an area with low humidity.

[0078] Therefore, based on the coefficient B of the area and the period information obtained from the management server 16 as the humidity information, the amount of moisture Y is calculated in accordance with the following equation (refer to Figure 5 ), and every time the amount of moisture Y exceeds a threshold value, the value of the moisture state indicating the deterioration state of the brake fluid 48 caused by the decrease in the boiling point is incremented by 1.

[0079] Y = B x T

[0080] where T is set to the period from the time point at which the value of the moisture state was last incremented by 1.

[0081] In Figure 5 , an example is shown in which the amount of moisture exceeds the threshold value in the area 1 with high humidity, and on the other hand, the amount of moisture does not exceed the threshold value in the area 2 with low humidity.

[0082] Note that, in a case where the staying is performed across a plurality of regions during a period from a time point at which the value of the moisture state is counted up by 1 last time, the moisture amount Y is calculated for each of the regions based on the coefficient B and the period information of the region, and the moisture amounts Y are added (refer to Figure 6 ).

[0083] In Figure 6 , an example of the relationship between the moisture amount and the period in a case where the staying is performed across a region 1 with high humidity and a region 2 with low humidity is shown.

[0084] The state estimation section 36 estimates a value obtained by adding the value of the heat state to the value of the moisture state as the deterioration state of the brake fluid 48. As shown in Figure 7 , the state estimation section 36 displays the deterioration state of the brake fluid 48 on a display (omitted from illustration) of the on-vehicle device 11. In Figure 7 , an example in which the deterioration state of the brake fluid 48 is displayed in four levels is shown. Note that, it can also be configured to display the deterioration state of the brake fluid 48 on a terminal (for example, a diagnostic machine) on the dealer side connected to the on-vehicle device 11.

[0085] (Management Server)

[0086] The management server 16 stores coefficients indicating the relationship between the moisture amount contained in the brake fluid and the period for each region, which are prepared in advance, as humidity information. With respect to the management server 16, when the position of the vehicle 12 acquired by the position acquisition section 30 is received from the on-vehicle device 11, the coefficients indicating the relationship between the moisture amount contained in the brake fluid and the period, which are stored as the humidity information corresponding to the region including the position of the vehicle 12, are transmitted to the on-vehicle device 11 via the network N.

[0087] (Flow of Processing)

[0088] Next, the flow of the processing in the vehicle system 10 of the first embodiment will be described using the flowchart of Figure 8 .

[0089] First, in the running of the vehicle 12, the control ECU 20 of the on-vehicle device 11 acquires the air temperature detected by the temperature sensor 22, the vehicle speed detected by the vehicle speed sensor 24, the hydraulic pressure of the brake fluid 48 detected by the hydraulic sensor 52 of the brake device 18, and the regenerative amount detected by the hybrid ECU 26 every prescribed time.

[0090] Then, when the ignition switch (omitted from illustration) of the vehicle 12 is set to off, the CPU 20A of the control ECU 20 of the on-vehicle device 11 executes the brake state estimation program 100, whereby the brake state estimation processing shown in Figure 8 is performed.

[0091] First, in step S100, the CPU 20A as the temperature acquisition section 34 accumulates the amount of change ΔT of the temperature of the brake disc over Δt seconds based on the air temperature detected by the temperature sensor 22, the vehicle speed detected by the vehicle speed sensor 24, the hydraulic pressure of the brake fluid 48 detected by the hydraulic sensor 52 of the brake device 18, and the amount of regeneration detected by the hybrid ECU 26, which are acquired at regular intervals, thereby calculating the temperature T of the brake disc at regular intervals R .

[0092] In step S102, the CPU 20A as the state estimation section 36 determines whether or not the temperature of the brake disc calculated in the above step S100 is equal to or below a threshold temperature. In the case where the temperature of the brake disc exceeds the threshold temperature, the CPU 20A moves to step S104. On the other hand, in the case where the temperature of the brake disc is equal to or below the threshold temperature, the CPU 20A moves to step S106. Note that the threshold temperature differs depending on the kind of brake fluid, such as the difference between the standards of DOT3, DOT4, DOT5.1, and the like in the Federal Motor Vehicle Safety Standard (FMVSS).

[0093] In step S104, the CPU 20A as the state estimation section 36 increments the value indicating the thermal state of the deterioration state of the brake fluid 48 caused by heat by 1, and moves to step S116.

[0094] In step S106, the CPU 20A as the position acquisition section 30 acquires the position of the vehicle 12.

[0095] In step S108, the CPU 20A as the information acquisition section 32 acquires period information indicating the period during which the area including the position of the vehicle is stayed, based on the position of the vehicle 12 acquired in the above step S106. Further, the CPU 20A as the information acquisition section 32 acquires humidity information based on the position of the vehicle 12 acquired in the above step S106.

[0096] In step S110, the CPU 20A as the state estimation section 36 calculates the amount of moisture based on the coefficient B of the area including the position of the vehicle 12 and the period information obtained as the humidity information in the above step S108.

[0097] In step S112, the CPU 20A determines, as the state estimation section 36, whether or not the water amount calculated in the above step S110 is below a threshold value. In a case where the water amount exceeds the threshold value, the CPU 20A moves to step S114. On the other hand, in a case where the water amount is below the threshold value, the CPU 20A ends the brake state estimation processing. Note that the threshold value related to the water amount differs depending on a difference in kind of the brake fluid.

[0098] In step S114, the CPU 20A, as the state estimation section 36, increments the value of the water state indicating the deterioration state of the brake fluid 48 caused by the boiling point depression by 1.

[0099] In step S116, the CPU 20A, as the state estimation section 36, estimates a value obtained by adding the value of the heat state to the value of the water state as the deterioration state of the brake fluid 48.

[0100] In step S118, the CPU 20A displays the deterioration state of the brake fluid 48 on a display (omitted from illustration) of the vehicle-mounted device 11 and ends the brake state estimation processing.

[0101] (Summary of the First Embodiment)

[0102] The vehicle 12 of the present embodiment is configured such that the control ECU 20 estimates the water state contained in the brake fluid based on the humidity information and the period information, estimates the heat state of the brake fluid based on the temperature of the brake device, and estimates the deterioration state of the brake fluid based on the water state and the heat state. In this way, the control ECU 20 estimates the deterioration state of the brake fluid taking into account the water state and the heat state of the brake fluid. Thus, the deterioration state of the brake fluid can be estimated with good precision by a simple configuration.

[0103] Further, the management server 16 is configured to store, as the humidity information, the coefficient indicating the relationship between the water amount contained in the brake fluid and the period for each region. Thus, the change of the coefficient indicating the relationship between the water amount contained in the brake fluid and the period for each region can be easily performed on the management server 16 side.

[0104] Further, when the ignition switch of the vehicle 12 is set to off, various information is transmitted from the vehicle-mounted device 11 to the management server 16, so the communication load can be reduced.

[0105] [Second Embodiment]

[0106] In the first embodiment, the moisture state of the brake fluid is estimated based on humidity information and period information, the thermal state of the brake fluid is estimated based on the temperature of the brake device, and the deterioration state of the brake fluid is estimated based on the moisture state and the thermal state. In contrast, in the second embodiment, which differs from the first embodiment in that a learned model for estimating the deterioration state of the brake fluid based on the temperature of the brake device, humidity information, and period information is used to estimate the deterioration state of the brake fluid. Hereinafter, the differences from the first embodiment will be described. Note that the same reference numerals are assigned to the same components, and the description thereof will be omitted.

[0107] (Vehicle)

[0108] The state estimation section 36 of the in-vehicle device 11 of the present embodiment estimates the deterioration state of the brake fluid 48 using a learned model for estimating the deterioration state of the brake fluid 48 based on humidity information, period information indicating the period of stay in the region including the position of the vehicle, and the temperature of the brake device 18.

[0109] Specifically, a learned model that takes as inputs the coefficient of the region obtained as humidity information, period information indicating the period of stay in the region including the position of the vehicle, and the temperature of the brake device 18, and outputs a level indicating the deterioration state of the brake fluid 48 is prepared in advance. Note that the learned model differs depending on the difference in the kind of the brake fluid 48.

[0110] Then, the state estimation section 36 inputs the coefficient of the region obtained as humidity information, period information indicating the period of stay in the region including the position of the vehicle, and the temperature of the brake device 18 to the learned model, and outputs the output of the learned model as the estimation result of the deterioration state of the brake fluid 48.

[0111] (Flow of processing)

[0112] Next, the flow of processing in the vehicle system 10 of the second embodiment will be described using the flowchart of Fig. 6. Figure 9

[0113] First, in the running of the vehicle 12, the control ECU 20 of the in-vehicle device 11 acquires the air temperature detected by the temperature sensor 22, the vehicle speed detected by the vehicle speed sensor 24, the hydraulic pressure of the brake fluid 48 detected by the hydraulic pressure sensor 52 of the brake device 18, and the amount of regeneration detected by the hybrid ECU 26 at regular intervals.

[0114] Then, when the ignition switch (not shown) of the vehicle 12 is set to OFF, the CPU 20A of the control ECU 20 of the in-vehicle device 11 executes the brake state estimation program 100, whereby the Figure 9 ​The illustrated brake state estimation process. Note that the same reference numerals are assigned to the same processes as in the first embodiment, and detailed description is omitted.

[0115] First, in step S100, the CPU 20A as the temperature acquisition section 34 accumulates the amount of change ΔT in the temperature of the brake disc over Δt seconds based on the air temperature detected by the temperature sensor 22, the vehicle speed detected by the vehicle speed sensor 24, the hydraulic pressure of the brake fluid 48 detected by the hydraulic sensor 52 of the brake device 18, and the amount of regeneration detected by the hybrid ECU 26, which are acquired at regular intervals, and thereby calculates the temperature T of the brake disc at regular intervals R .

[0116] In step S106, the CPU 20A as the position acquisition section 30 acquires the position of the vehicle 12.

[0117] In step S108, the CPU 20A as the information acquisition section 32 acquires period information indicating the period during which the vehicle 12 stays in the region including the position of the vehicle, based on the position of the vehicle 12 acquired in the above step S106. Further, the CPU 20A as the information acquisition section 32 acquires humidity information based on the position of the vehicle 12 acquired in the above step S106.

[0118] In step S200, the CPU 20A as the state estimation section 36 inputs the maximum temperature of the temperature of the brake disc calculated in the above step S100, the coefficient of the region including the position of the vehicle 12, and the period information obtained as the humidity information in the above step S108, to the learned model, and estimates the deterioration state of the brake fluid 48.

[0119] In step S118, the CPU 20A displays the deterioration state of the brake fluid 48 on the display (omitted from illustration) of the on-vehicle device 11, and ends the brake state estimation process.

[0120] (Summary of the Second Embodiment)

[0121] The vehicle 12 of the present embodiment is configured such that the control ECU 20 estimates the deterioration state of the brake fluid using a learned model for estimating the deterioration state of the brake fluid based on the temperature of the brake device, humidity information, and period information. Thereby, the deterioration state of the brake fluid can be estimated with good precision by a simple configuration.

[0122] [Third Embodiment]

[0123] In the first and second embodiments, the deterioration state of the brake fluid is estimated in the on-vehicle device. In contrast, in the third embodiment, the deterioration state of the brake fluid of the vehicle is estimated on the management server side, which is different from the first and second embodiments. Hereinafter, the difference from the first embodiment will be described. Note that the same reference numerals are given to the same configurations, and the description will be omitted.

[0124] (Overall Configuration)

[0125] As described above Figure 1 , the vehicle system 310 of the present embodiment includes the vehicle 12 and the management server 316.

[0126] (Vehicle)

[0127] The on-vehicle device 11 mounted on the vehicle 12 acquires the latitude and longitude of the position of the vehicle 12 from the navigation system mounted on the vehicle 12 at regular intervals, and transmits to the management server 316 through the communication section 14.

[0128] The on-vehicle device 11 acquires the air temperature detected by the temperature sensor 22, the vehicle speed detected by the vehicle speed sensor 24, the hydraulic pressure of the brake fluid 48 detected by the hydraulic pressure sensor 52 of the brake device 18, and the amount of regeneration detected by the hybrid ECU 26 at regular intervals, and transmits to the management server 316 through the communication section 14.

[0129] Further, the on-vehicle device 11 acquires the estimation result of the deterioration state of the brake fluid from the management server 316, and displays on the display (omitted from the drawing) of the on-vehicle device 11.

[0130] (Management Server)

[0131] As Figure 10 indicated, the management server 316 is configured to include a control device 380 and a communication section 316B.

[0132] The control device 380 is provided with a CPU 382, a ROM 383, a RAM 384, an external storage 385, and an input / output I / F 386. The CPU 382, the ROM 383, the RAM 384, the external storage 385, and the input / output I / F 386 are connected to each other via a bus 388. The CPU 382 is one example of a processor, and the RAM 384 is one example of an internal storage.

[0133] As for the functions of the CPU 382, the ROM 383, the RAM 384, the external storage 385, and the input / output I / F 386, the same as the CPU 20A, the ROM 20B, the RAM 20C, the external storage 20D, and the input / output I / F 20E described above.

[0134] CPU 382 reads the braking state estimation program 300 from external memory 385 and executes the program using RAM 384 as the working area. In this embodiment, the braking state estimation program 300 is stored in external memory 385.

[0135] The communication unit 316B is connected to the control device 380 of this embodiment via the input / output I / O 386. It should be noted that the communication unit 316B can also be directly connected to the bus 388.

[0136] like Figure 11 As shown, in the control device 380 of this embodiment, the CPU 382 executes the braking state estimation program 300, thereby functioning as the position acquisition unit 330, the information acquisition unit 332, the temperature acquisition unit 334, and the state estimation unit 336.

[0137] The location acquisition unit 330 acquires the latitude and longitude of the vehicle 12's location received from the vehicle-mounted unit 11 of the vehicle 12.

[0138] The information acquisition unit 332 acquires period information indicating the duration of stay in the area including the vehicle's location, based on the location of the vehicle 12 acquired by the location acquisition unit 330. Furthermore, the information acquisition unit 332 acquires humidity information based on the location of the vehicle 12 acquired by the location acquisition unit 330. For example, the information acquisition unit 332 maintains a pre-prepared coefficient representing the relationship between the amount of water contained in the brake fluid and the duration for each area as humidity information. The information acquisition unit 332 acquires a coefficient representing the relationship between the amount of water contained in the brake fluid and the duration, which is the humidity information corresponding to the area including the location of the vehicle 12 acquired by the location acquisition unit 330.

[0139] The temperature acquisition unit 334 acquires the temperature of the braking device 18 received from the vehicle's onboard unit 11. Specifically, the temperature acquisition unit 334 calculates the temperature of the braking device 18 based on the air temperature detected by the temperature sensor 22, the vehicle speed detected by the vehicle speed sensor 24, the brake fluid pressure detected by the brake fluid sensor 52, and the regeneration amount detected by the hybrid ECU 26, in the same manner as the temperature acquisition unit 34 of the first embodiment described above.

[0140] The state estimation unit 336 estimates the deterioration state of the braking fluid 48 based on humidity information, duration information indicating the period of stay in the area including the vehicle's location, and the temperature of the braking device 18.

[0141] Specifically, the state estimation section 336 estimates the moisture state of the brake fluid 48 contained based on the humidity information and the period information, estimates the thermal state of the brake fluid 48 based on the temperature of the brake device 18, and estimates the deterioration state of the brake fluid 48 based on the moisture state and the thermal state, similarly to the state estimation section 36 in the first embodiment described above.

[0142] The state estimation section 336 transmits the estimation result of the deterioration state of the brake fluid 48 to the vehicle-mounted device 11 via the network N through the communication section 316B.

[0143] (Flow of processing)

[0144] First, in the running of the vehicle 12, the control ECU 20 of the vehicle-mounted device 11 acquires the air temperature detected by the temperature sensor 22, the vehicle speed detected by the vehicle speed sensor 24, the hydraulic pressure of the brake fluid 48 detected by the hydraulic pressure sensor 52 of the brake device 18, and the amount of regeneration detected by the hybrid ECU 26 every prescribed time, and transmits them to the management server 316 through the communication section 14.

[0145] Further, the vehicle-mounted device 11 acquires the latitude and longitude of the position of the vehicle 12 from the navigation system mounted on the vehicle 12 at regular intervals, and transmits them to the management server 316 through the communication section 14.

[0146] Then, when the ignition switch (omitted from the drawing) of the vehicle 12 is set to off, the vehicle-mounted device 11 transmits a request for estimation of the deterioration state of the brake fluid 48 to the management server 316 through the communication section 14.

[0147] Then, when the management server 316 receives the request for estimation of the deterioration state of the brake fluid 48 from the vehicle-mounted device 11, the CPU 382 of the control device 380 of the management server 316 executes the brake state estimation program 300, whereby the same processing as the brake state estimation processing described above with reference to FIG. 8 is performed. Figure 8

[0148] (Summary of the third embodiment)

[0149] The management server 316 of the present embodiment is configured such that the control device 380 estimates the moisture state of the brake fluid contained based on the humidity information and the period information, estimates the thermal state of the brake fluid based on the temperature of the brake device, and estimates the deterioration state of the brake fluid based on the moisture state and the thermal state. In this way, the control device 380 estimates the deterioration state of the brake fluid taking into account the moisture state and the thermal state of the brake fluid. Thus, the deterioration state of the brake fluid can be estimated with good precision by a simple configuration.

[0150] ​Further, the management server 316 is configured to estimate the moisture state of the brake fluid based on the humidity information and the period information, and estimate the thermal state of the brake fluid based on the temperature of the brake device. Thereby, the change of the threshold value related to the moisture state and the thermal state can be easily performed at the management server 316 side.

[0151] (Modification of the Third Embodiment)

[0152] In the third embodiment, the case where the management server 316 estimates the moisture state of the brake fluid based on the humidity information and the period information, estimates the thermal state of the brake fluid based on the temperature of the brake device, and estimates the deterioration state of the brake fluid based on the moisture state and the thermal state is described, but is not limited thereto. The state estimation section 336 of the management server 316 can also input the coefficient of the region obtained as the humidity information, the period information indicating the period of staying in the region including the position of the vehicle, and the temperature of the brake device 18 to the learned model as with the second embodiment described above, and output the learned model as the estimation result of the deterioration state of the brake fluid 48. In this case, the CPU 382 of the control device 380 of the management server 316 executes the brake state estimation program 300, whereby the same processing as the brake state estimation processing shown in Fig. 8 is performed. Figure 9

[0153] Further, the case where the control ECU 20 of the on-vehicle device 11 acquires the air temperature detected by the temperature sensor 22, the vehicle speed detected by the vehicle speed sensor 24, the hydraulic pressure of the brake fluid 48 detected by the hydraulic pressure sensor 52 of the brake device 18, and the regenerative amount detected by the hybrid ECU 26 at a prescribed time interval, and transmits them to the management server 316 through the communication section 14 is described, but is not limited thereto. The control ECU 20 of the on-vehicle device 11 can also be configured to calculate the temperature of the brake disc based on the air temperature detected by the temperature sensor 22, the vehicle speed detected by the vehicle speed sensor 24, the hydraulic pressure of the brake fluid 48 detected by the hydraulic pressure sensor 52 of the brake device 18, and the regenerative amount detected by the hybrid ECU 26 acquired at a prescribed time interval, and transmit the calculation result to the management server 316 through the communication section 14.

[0154] [Notes]

[0155] In each of the above embodiments, the case where the air temperature is detected by the temperature sensor 22 is described, but is not limited thereto. The air temperature in the region including the position of the vehicle 12 can also be acquired from an external server.

[0156] ​Moreover, various processes performed by the CPU 20A, the CPU 382 in the above-described embodiments to read in software (programs) and execute them can also be performed by various processors other than the CPU. As the processor in this case, a PLD (Programmable Logic Device) such as an FPGA (Field-Programmable Gate Array) that can change the circuit configuration after manufacture, and an ASIC (Application Specific Integrated Circuit) and the like that are special-purpose electric circuits as processors having a circuit configuration designed specifically to perform a certain process can be exemplified. Moreover, either one of these various processors can perform the various processes, or a combination of two or more processors of the same kind or different kinds (for example, a combination of a plurality of FPGAs and a CPU and an FPGA, and the like) can perform the various processes. Moreover, more specifically, the hardware configuration of these various processors is an electric circuit in which circuit elements such as semiconductor elements are combined.

[0157] Moreover, in the above-described embodiments, the case in which each program is stored (installed) in advance in a non-transitory recording medium that is readable by a computer has been described. For example, in the on-vehicle device 11, the brake state estimation program 100 is stored in advance in the external storage 20D. Moreover, for example, in the management server 316, the brake state estimation program 300 is stored in advance in the external storage 385. However, this is not limiting, and each program can also be provided in the form of being recorded in a non-transitory recording medium such as a CD-ROM (Compact Disc Read Only Memory), a DVD-ROM (Digital Versatile Disc Read Only Memory), and a USB (Universal Serial Bus) memory. Moreover, each program can also be provided in the form of being downloaded from an external device via a network.

[0158] The flow of the processes described in the above-described embodiments is also one example, and an unnecessary step can be deleted, a new step can be added, or the order of the processes can be changed within a range that does not depart from the gist.

[0159] In addition to this, the configuration of each of the on-vehicle device and the management server described in the above-described embodiments is one example, and can be changed according to the situation within a range that does not depart from the gist.

Claims

1. A brake state estimation device comprising: a position acquisition section that acquires a position of a subject vehicle; and a state estimation section that estimates a deterioration state of brake fluid for operating a hydraulic brake device of the subject vehicle based on humidity information corresponding to the position of the subject vehicle and period information indicating a period of stay in a region including the position of the subject vehicle, the humidity information being a coefficient prepared in advance for each of the regions indicating a relationship between an amount of moisture contained in the brake fluid and the period of stay in the region.

2. The brake state estimation device according to claim 1, further comprising a temperature acquisition section that acquires a temperature of the brake device, the state estimation section estimating the deterioration state of the brake fluid based on the temperature of the brake device, the humidity information, and the period information.

3. The brake state estimation device according to claim 2, wherein the state estimation section estimates a moisture state contained in the brake fluid based on the humidity information and the period information, the state estimation section estimates a thermal state of the brake fluid based on the temperature of the brake device, the state estimation section estimates the deterioration state of the brake fluid based on the moisture state and the thermal state.

4. The brake state estimation device according to claim 2, wherein the state estimation section estimates the deterioration state using a learned model for estimating the deterioration state of the brake fluid based on the temperature of the brake device, the humidity information, and the period information.

5. A vehicle comprising: the brake state estimation device according to any one of claims 1 to 4; and the hydraulic brake device.

6. A brake state estimation method in which a position acquisition section acquires a position of a subject vehicle, a state estimation section estimates a deterioration state of brake fluid for operating a hydraulic brake device of the subject vehicle based on humidity information corresponding to the position of the subject vehicle and period information indicating a period of stay in a region including the position of the subject vehicle, the humidity information being a coefficient prepared in advance for each of the regions indicating a relationship between an amount of moisture contained in the brake fluid and the period of stay in the region.

7. A computer-readable recording medium recording a program for causing a computer to execute: acquiring a position of a subject vehicle, estimating a deterioration state of brake fluid for operating a hydraulic brake device of the subject vehicle based on humidity information corresponding to the position of the subject vehicle and period information indicating a period of stay in a region including the position of the subject vehicle, the humidity information being a coefficient prepared in advance for each of the regions indicating a relationship between an amount of moisture contained in the brake fluid and the period of stay in the region.

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