JP2021060096A - Vehicular brake alarm device - Google Patents

Abstract

To provide a vehicular brake alarm device capable of accurately issuing an alarm related to a vapor lock phenomenon occurring in a brake fluid in a vehicular brake device.SOLUTION: A vehicular brake alarm device includes temperature detecting means 35 for detecting a temperature of a brake fluid, water content detecting means 37 for detecting a water content of the brake fluid, a boiling point temperature map 39 in which relation between the water content contained in the brake fluid and the boiling point temperature is set for each type of the brake fluid, an alarm threshold temperature setting section 41 for determining a boiling point temperature in correspondence with the water content detected by the water content detecting means with the usage of the boiling point temperature map and setting an alarm threshold temperature based on the determined boiling point temperature, and a first alarm control section 43 for issuing a first alarm when the temperature detected by the temperature detecting means is equal to or higher than the alarm threshold temperature set by the alarm threshold temperature setting section.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to an alarm device for a vehicle brake, and more particularly to an alarm device for a so-called vapor lock phenomenon in which air bubbles are generated in a brake fluid.

In the brake device of a vehicle, the vapor lock phenomenon is known as a phenomenon in which bubbles (steam) are generated by boiling due to overheating of the brake fluid inside the hydraulic system of the foot brake. Even if the brake pedal is depressed in this state, the air bubbles absorb the pressure and the braking effect is significantly deteriorated.

Patent Document 1 accurately and reliably detects information related to a phenomenon that causes an extremely serious situation with respect to the operation of the braking device, such as the vapor lock phenomenon, without requiring a large-scale modification of the braking device. It shows a braking device monitoring system for vehicles that can inform the driver.

Specifically, the driver is provided with a sensor built into the banjo bolt used when connecting the brake hose to the brake caliper and a parameter indicating the state of the brake fluid generated based on the sensor signal detected by the sensor. It is shown that the sensor includes at least one of the parameters selected from the group consisting of temperature, moisture and pressure, which comprises a notifying means for notifying.

Further, Patent Document 2 discloses not only fading but also a brake alarm display device that can be recognized by the driver before vapor lock occurs and has good space efficiency in the installation space. A brake oil temperature sensor or the like for measuring the oil temperature of the braking force transmitting means is provided, and a picture or the like based on the oil temperature measured by the brake oil temperature sensor is displayed in a meter device arranged at a position visible from the driver's seat. It is shown that a display is provided to display as needed.

Japanese Patent No. 6366867 Japanese Unexamined Patent Publication No. 2005-2266659

As mentioned above, Patent Document 1 shows that the sensor detects at least one of the parameters selected from the group consisting of temperature, moisture and pressure, and Patent Document 2 states that before vapor lock occurs, A brake alarm display device that can be recognized by the driver and has good space efficiency in the installation space is shown, but in all patent documents, the type of brake fluid (the type specified in the specifications for each vehicle type). ), The specific configuration for issuing an alarm regarding the vapor lock phenomenon is not shown in consideration of the fact that the boiling point temperature differs depending on the state of the brake fluid (moisture content).

It is desirable to consider that the boiling point temperature differs depending on the type of the brake fluid and the water content state of the brake fluid in the alarm regarding the accurate vapor lock phenomenon.

Further, Patent Documents 1 and 2 mainly detect predictive information before the vapor lock phenomenon occurs with high accuracy and notify the driver, and the vapor lock phenomenon occurs due to the generation of air bubbles in the brake fluid. It is not intended to inform you and call your attention. Warning that air bubbles have already been generated is important in encouraging the driver to take immediate action, such as stopping the vehicle and cooling the braking system. ..

Therefore, in view of the above problems, at least one embodiment of the present invention aims to provide a vehicle brake alarm device capable of accurately issuing an alarm regarding a vapor lock phenomenon occurring in brake fluid in a vehicle brake device. And.

(1) It was invented to achieve the above-mentioned object, and at least one embodiment of the present invention applies a braking force generated by stepping on a brake pedal with a brake fluid filled in a brake pipe. A vehicle brake alarm device used for a brake device to transmit the brake fluid to, the temperature detecting means for detecting the temperature of the brake fluid, the water content detecting means for detecting the water content of the brake fluid, and the brake fluid. A boiling temperature map in which the relationship between the water content contained in the brake fluid and the boiling temperature is set for each type, and a boiling point corresponding to the water content detected by the water content detecting means using the boiling temperature map. The alarm threshold temperature setting unit that determines the temperature and sets the alarm threshold temperature based on the determined boiling temperature, and the temperature detected by the temperature detecting means are the alarm threshold temperature set by the alarm threshold temperature setting unit. A first alarm control unit that issues a first alarm at the above time is provided.

According to such a configuration, the alarm threshold temperature for issuing the first alarm by the first alarm control unit is determined by the type of brake fluid and the water content contained in the brake fluid using the boiling point temperature map. Since it is set based on the boiling point temperature, it is possible to accurately issue an alarm regarding the vapor lock phenomenon that occurs in the brake fluid.

The main component of commonly used glycol-based brake fluid is polyethylene glycol monoether, and since this polyethylene glycol monoether is soluble in water, glycol is not the only part of the water that boils at 100 ° C. The boiling point temperature of the brake fluid of the system (the temperature at which the brake fluid boils) has different properties depending on the state of the water content in the brake fluid (dry state, wet state).

Further, the boiling point temperature of the brake fluid has a property that the boiling point temperature differs because the contained component and the content of the contained component differ depending on the type of brake fluid used, that is, the standard.

As described above, the boiling point temperature of the glycol-based brake fluid is greatly affected by the type (standard) of the brake fluid and the water content of the brake fluid. Therefore, in the present invention, the brake fluid can be obtained by considering these. It is possible to accurately notify an alarm regarding the vapor lock phenomenon that occurs.

(2) In some embodiments, a bubble detecting means for detecting bubbles generated in the brake fluid, a second alarm control unit for issuing a second alarm when the generation of bubbles is detected by the bubble detecting means, and a second alarm control unit. It is characterized by further providing.

According to such a configuration, the second alarm control unit can notify that bubbles are generated in the brake fluid to cause the vapor lock phenomenon. As a result, it alerts the driver that air bubbles have already been generated and promptly takes countermeasures, such as stopping the vehicle and cooling the braking device. Can be prompted.

(3) In some embodiments, the second alarm control unit issues the second alarm in addition to the first alarm by the first alarm control unit.

According to such a configuration, the second alarm by the second alarm control unit is warned so as to overlap with the first alarm by the first alarm control unit, so that a strong warning can be notified to the driver. Further, since the first alarm based on the temperature determination and the second alarm based on the bubble determination give an alarm in two stages, the driver can be surely alerted to the vapor lock phenomenon.

(4) In some embodiments, the water content detecting means injects the brake fluid into the brake pipe and is in a reserve tank in which the brake fluid is stored, and the brake fluid is stored. It is characterized in that it is installed in a position where it is immersed in.

According to such a configuration, the vicinity of the reserve tank where the brake fluid is injected is the most exposed to moisture, and the brake fluid is the most deteriorated due to the large amount of moisture, so the sensor is installed in another location. Since the deterioration state can be detected earlier than that of the above, it is possible to accurately issue an alarm regarding the vapor lock phenomenon.

(5) In some embodiments, the bubble detecting means and the temperature detecting means are provided immediately before the brake caliper to which the brake pipe is connected.

According to such a configuration, immediately before the brake caliper to which the brake pipe is connected, the temperature of the brake fluid is most affected by the heat from the brake caliper, and bubbles are likely to be generated in the brake fluid. By installing a temperature detecting means for detecting the temperature of the brake fluid and a bubble detecting means for detecting the bubbles generated in the brake fluid, it is possible to accurately issue an alarm regarding the vapor lock phenomenon.

(6) In some embodiments, the boiling point temperature map measures the bubble detection temperature corresponding to the water content of the brake fluid as the boiling point temperature for each type of brake fluid by a test in advance, and the type of brake fluid. It is characterized in that it is created by a boiling point temperature map creating means that sets the relationship between the water content contained in the brake fluid and the boiling point temperature for each time.

According to such a configuration, the water content contained in the brake fluid for each type of brake fluid is measured in advance by measuring the bubble detection temperature corresponding to the water content of the brake fluid as the boiling point temperature for each type of brake fluid. By setting the relationship between the content and the boiling point temperature, the boiling point temperature map can be easily created.

According to at least one embodiment of the present invention, it is possible to accurately issue an alarm regarding the vapor lock phenomenon that occurs in the brake fluid in the braking device of the vehicle.

It is an overall block diagram of the brake alarm device of the vehicle which concerns on one Embodiment of this invention. It is a flowchart which shows the control flow of the brake alarm control device in embodiment shown in FIG. It is a block diagram which shows the outline of making a boiling point temperature map. It is a flowchart which shows the creation flow in the boiling point temperature map creation means shown in FIG. It is a block diagram of the whole structure of the brake alarm device of the vehicle which concerns on another embodiment. It is a flowchart which shows the control flow of the brake alarm control device in another embodiment shown in FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the relative arrangement of the components described as the embodiment or shown in the drawings is not intended to limit the scope of the present invention to these, and is merely an explanatory example.

An embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 shows an overall block diagram of a vehicle brake alarm device 1 according to an embodiment of the present invention, and FIG. 2 shows a flowchart showing a control flow of the brake alarm control device 3.

As shown in FIG. 1, the brake alarm device 1 is used for the brake device 11 that transmits the braking force generated by depressing the brake pedal 9 to wheels (not shown) of the vehicle by the brake fluid 7 filled in the brake pipe 5. Be done.

As shown in FIG. 1, the brake device 11 shows the case of a disc brake as an example. The brake device 11 is mainly integrated with a brake pedal 9 provided in the driver's seat and operated by the driver 13, a booster 15 for increasing the stepping force acting on the brake pedal 9, and a booster 15. A master cylinder 17 that is provided to generate a brake fluid pressure according to a stepping force acting on the brake pedal 9, a brake pipe 5 that connects the master cylinder 17 and a disc brake mechanism 19 of each wheel, and a master cylinder 17 The brake fluid 7 is injected into the inside of the brake pipe 5 and has a reserve tank 23 in which the brake fluid 7 is stored so as to be constantly filled.

As shown in FIG. 1, the disc brake mechanism 19 presses the inner brake pad 27 against the brake disc 25 made of a steel disk rotating together with the wheels via the piston 29. The outer brake pad 31 is fixed to the brake caliper 33, and when the inner brake pad 27 is pushed by the piston 29, the entire brake caliper 33 tries to move inward, whereby the outer brake pad 31 also tries to move the brake disc 25. Is pressed against. Then, the brake disc 25 is sandwiched between the inner brake pad 27 and the outer brake pad 31.

In this way, the braking force generated by depressing the brake pedal 9 is transmitted to the piston 29 via the brake fluid 7, the piston 29 is pushed out, and the inner brake pad 27 and the outer brake pad 31 are pushed to the brake disc 25. It is pressed against the brake to generate braking force.

The brake alarm device 1 used in the brake device 11 of a vehicle having the above configuration includes a temperature sensor 35 as a temperature detecting means for detecting the temperature of the brake fluid 7 in the brake pipe 5, and a water content in the brake fluid 7. It is provided with a moisture sensor 37 as a moisture content detecting means for detecting the above, and a brake alarm control device 3 for controlling an alarm regarding a vapor lock phenomenon occurring in the brake fluid 7.

The brake alarm control device 3 has a boiling point temperature map 39 and a boiling point temperature map 39 in which the relationship between the water content contained in the brake fluid 7 and the boiling point temperature is set for each type (standard) of the brake fluid 7 used. The boiling point temperature corresponding to the water content detected by the moisture sensor 37 is determined using the above, and the alarm threshold temperature setting unit 41 that sets the alarm threshold temperature based on the determined boiling point temperature and the temperature sensor 35 detect it. It includes a first alarm control unit 43 that issues a first alarm when the temperature is equal to or higher than the alarm threshold temperature set by the alarm threshold temperature setting unit 41.

Further, in the brake alarm device 1, a first alarm device 45 for issuing a first alarm, for example, a warning light is installed in a meter panel or an instrument panel in front of the driver's seat.

Regarding the moisture sensor 37 that detects the moisture content in the brake fluid 7, for example, Mother Tool Co., Ltd. or "Brake Fluid Tester" of Esco Co., Ltd. is known as a device for measuring the moisture content of the brake fluid. .. It can be detected using these testers or by using the principles of these testers.

The alarm threshold temperature setting unit 41 was determined by using the boiling point temperature map 39 in order to issue an alarm when the temperature approaches the boiling point temperature in consideration of the function as an alarm before the vapor lock phenomenon occurs. The alarm threshold temperature is set to a temperature lower than the boiling point temperature by a predetermined temperature.

In the boiling point temperature map 39, the relationship between the water content contained in the brake fluid 7 and the boiling point temperature is set for each type (standard) of the brake fluid 7 used, and the boiling point temperature map creating means shown in FIG. Created by 47. FIG. 3 shows an overall configuration diagram for creating a boiling point temperature map, and FIG. 4 shows a procedure for creating a boiling point temperature map 39 by the boiling point temperature map creating means 47.

In the map-creating brake device 51 shown in FIG. 3, the brake device 11 of the embodiment of FIG. 1 is further provided with a bubble sensor 53 as a bubble detecting means for detecting whether bubbles are generated in the brake fluid 7. ..

The principle of this bubble sensor 53 is that ultrasonic waves have the property of easily propagating in a liquid, but when air (bubbles) is present in the liquid, the propagation efficiency is low and the reception intensity of ultrasonic waves is also weakened. .. Bubble detection is performed using this relationship. For example, Honda Electronics Co., Ltd. "Bubble detection sensor" is known.

As shown in FIG. 4, in the procedure for creating the boiling point temperature map 39, first, in step S21, the water content in the brake fluid 7 is detected by the water sensor 37. In the next step S22, the temperature of the brake fluid 7 is detected by the temperature sensor 35. In the next step S23, the data from the bubble sensor 53 is acquired, and it is determined whether or not it is detected that the brake fluid 7 has generated bubbles in the next step S24.

If it is not detected in step S24 that air bubbles have been generated in the brake fluid 7, the process proceeds to step S25 to raise the temperature of the brake fluid 7, returns to step S21, and repeats from step S21. When it is detected that bubbles are generated in the brake fluid 7 in step S24, the process proceeds to step S26, and in step S26, the fluid temperature at which the bubbles are generated is set as the boiling point temperature with respect to the water content for each water content. ..

In the same procedure, the type (standard) of the brake fluid 7 is changed and the boiling point temperature map 39 for each type of the brake fluid 7 is created. In this way, by a test in advance, the bubble detection temperature for each water content of the brake fluid is measured as the boiling point for each type of brake fluid 7, and the type of brake fluid and the water content and boiling point contained in the brake fluid are measured. The relationship with temperature can be set. In this way, the boiling point temperature map 39 can be easily created.

Next, the control flow of the brake alarm control device 3 according to the embodiment of FIG. 1 having the above configuration will be described with reference to the flowchart of FIG.

First, in step S1, the water content in the brake fluid 7 is detected by the water sensor 37. In the next step S2, the boiling point temperature map 39 already created is referred to, and in step S3, the boiling point temperature with respect to the water content detected in step S1 using the boiling point temperature map 39 corresponding to the type of brake fluid used is used. To determine.

In the next step S4, a temperature lower than the boiling point temperature determined in step S3 by a predetermined temperature is set as the alarm threshold temperature. In the next step S5, the temperature sensor 35 detects the current temperature of the brake fluid 7. Then, in the next step S6, it is determined whether the actual temperature of the brake fluid 7 detected by the temperature sensor 35 is equal to or higher than the alarm threshold temperature.

If the determination result in step S6 is No, the process returns to step S1 and repeats from step S1. If the determination result in step S6 is Yes, the process proceeds to step S7, and in step S7, the warning light of the first alarm 45 is turned on or blinks to notify the driver that the vapor lock phenomenon is about to occur. To call attention.

According to the embodiment shown in FIGS. 1 and 2 above, the alarm threshold temperature for turning on or blinking the warning light of the first alarm device 45 by the first alarm control unit 43 is set to the brake fluid by using the boiling point temperature map 39. Based on the boiling point temperature determined by the type of brake fluid and the water content contained in the brake fluid, the temperature is set to a predetermined temperature lower than this boiling point temperature, so that the vapor lock phenomenon that occurs in the brake fluid 7 is close to occurring. Can be issued with high accuracy.

The main component of commonly used glycol-based brake fluid is polyethylene glycol monoether, which is soluble in water. In the soluble state, water molecules are surrounded by glycol ethers and the properties of water change, and even if water is mixed, not only the water part boils at 100 ° C, but in a dry state (new) where there is no water. The presence of water relative to the boiling point of the brake fluid causes a phenomenon in which the boiling point is lowered as a whole. Therefore, the boiling point temperature of the glycol-based brake fluid has different properties depending on the state of the water content of the brake fluid (dry state, wet state).

The boiling point temperature of the brake fluid differs depending on the type of brake fluid, for example, the DOT standard such as DOT3 and DOT4. DOT (Department Of Transportation) is an abbreviation for the US Department of Transportation, and the DOT standard is a standard based on the FMVSS standard (Federal Motor Vehicle Safety Standards). It has the property that the boiling point temperature differs because the content of the contained component and the content of the contained component differ depending on the type of brake fluid used, that is, the standard.

As described above, the boiling temperature of the glycol-based brake fluid is greatly affected by the type of brake fluid and the water content of the brake fluid. Therefore, in the present embodiment, the vapor lock phenomenon that occurs in the brake fluid is taken into consideration. It is possible to accurately notify the alarm regarding.

In some embodiments, as shown in FIG. 1, the moisture sensor 37 injects the brake fluid 7 into the brake pipe 5 and is in the reserve tank 23 in which the brake fluid 7 is stored, and the stored brake. It is configured to be installed in a position where it is immersed in the fluid 7.

According to such a configuration, the vicinity of the reserve tank 23, which is the injection point of the brake fluid 7, is most exposed to moisture, and the brake fluid 7 is the most deteriorated due to the large amount of moisture. Since the deterioration state can be detected earlier than the installation of the brake, it is possible to accurately issue an alarm regarding the vapor lock phenomenon.

Further, in some embodiments, as shown in FIGS. 1, 3 and 5, which will be described later, the temperature sensor 35 and the bubble sensor 53 are provided immediately before the brake caliper 33 to which the brake pipe 5 is connected. It is composed.

According to such a configuration, immediately before the brake caliper 33 to which the brake pipe 5 is connected, the temperature of the brake fluid 7 is most affected by the heat from the brake caliper 33, and bubbles are generated in the brake fluid 7. Cheap. Therefore, by installing the temperature sensor 35 that detects the temperature of the brake fluid 7 and the bubble sensor 53 that detects the bubbles generated in the brake fluid 7 at this location, it is possible to accurately issue an alarm regarding the vapor lock phenomenon. ..

Next, other embodiments will be described with reference to FIGS. 5 and 6. FIG. 5 shows an overall block diagram of the vehicle brake alarm device 61 according to another embodiment, and FIG. 6 shows a flowchart showing a control flow of the brake alarm control device 63.

As shown in FIG. 5, with respect to the embodiment shown in FIG. 1, the bubble sensor 53 as a bubble detecting means for detecting the bubbles generated in the brake fluid 7 and the bubble sensor 53 detected the generation of bubbles. A second alarm control unit 65 that issues a second alarm at the time is further provided. Further, the brake alarm device 61 includes a second alarm device 67 that issues a second alarm, for example, a warning sound generating unit that generates a warning sound. The same components as those of the embodiment shown in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

The control flow of the brake alarm control device 63 according to the embodiment of FIG. 5 having the above configuration will be described with reference to the flowchart of FIG.

Steps S1 to S7 are the same as those described in the flowchart of the embodiment of FIG. 2, and the process proceeds to step S11 after step S7. In step S11, the data from the bubble sensor 53 is acquired, and the next step is It is determined in step S12 whether or not it is detected that air bubbles have been generated in the brake fluid 7.

The detection of the generation of air bubbles in step S12 is when the air bubble sensor 53 simply detects the generation of air bubbles, and further, when the air bubble size or the amount of air bubbles generated which adversely affects the operation of the brake is detected. There may be. That is, as described above, the principle of the bubble sensor 53 is that ultrasonic waves have the property of easily propagating in a liquid, but when air (bubbles) is present in the liquid, the propagation efficiency becomes low and the ultrasonic waves Since it is detected by utilizing the fact that the reception intensity of the signal is also weakened, the bubble size or the amount of bubble generation that adversely affects the operation of the brake may be determined by setting a predetermined threshold value for the reception intensity.

If it is not detected in step S12 that air bubbles have been generated in the brake fluid 7, the process returns to step S1 and repeats from step S1. When it is detected that air bubbles have been generated in the brake fluid 7 in step S12, the process proceeds to step S13, and in step S13, a warning sound is emitted by the warning sound generating unit of the second alarm 67 to give the driver a vapor lock phenomenon. Notify that is occurring and call attention.

According to the above embodiments of FIGS. 5 and 6, the second alarm control unit 65 can notify that bubbles are generated in the brake fluid 7 to cause the vapor lock phenomenon. As a result, it alerts the driver that air bubbles have already been generated and promptly takes countermeasures, such as stopping the vehicle and cooling the braking device. Can be prompted.

Further, since the second alarm control unit 65 issues a warning sound of the second alarm device 67 in an overlapping manner in addition to the warning light of the first alarm device 45 by the first alarm control unit 43, the driver is informed. A strong warning can be sent.

Since the warning light of the first alarm 45 based on the temperature determination and the warning sound of the second alarm 67 based on the bubble determination give an alarm in two stages, the driver can be surely alerted to the vapor lock phenomenon. In the above embodiment, the first alarm device 45 is a warning light and the second alarm device 67 describes the warning sound, but the warning is not limited to such a warning sound.

For example, a map display of the navigation system installed in the instrument panel in front of the driver's seat or a multi-information display that displays various information displays warning characters and warning pictures as warning displays, and the display form is changed. 1 The first alarm by the alarm control unit 43 and the second alarm by the second alarm control unit 65 may be controlled to be displayed in a stepwise manner.

According to at least one embodiment of the present invention, the vehicle brake device can accurately issue an alarm regarding the vapor lock phenomenon that occurs in the brake fluid, and is therefore suitable for use in the vehicle brake alarm device.

1 Brake alarm device 3 Brake alarm control device 5 Brake piping 7 Brake fluid 9 Brake pedal 11 Brake device 15 Booster 17 Master cylinder 19 Disc brake mechanism 23 Reserve tank 25 Brake disc 27 Inner brake pad 29 Piston 31 Outer brake pad 33 Brake caliper 35 Temperature sensor (temperature detecting means)
37 Moisture sensor (moisture content detecting means)
39 Boiling point temperature map 41 Alarm threshold temperature setting unit 43 1st alarm control unit 45 1st alarm 47 Boiling point temperature map creation means 53 Bubble sensor (bubble detection means)
65 2nd alarm control unit 67 2nd alarm

Claims (6)

It is a vehicle brake warning device used for a brake device that transmits the braking force generated by stepping on the brake pedal with the brake fluid filled in the brake pipe to the wheels.
A temperature detecting means for detecting the temperature of the brake fluid and
A water content detecting means for detecting the water content of the brake fluid, and
A boiling point temperature map in which the relationship between the water content contained in the brake fluid and the boiling point temperature is set for each type of brake fluid.
An alarm threshold temperature setting unit that determines a boiling point temperature corresponding to the water content detected by the water content detecting means using the boiling point temperature map and sets an alarm threshold temperature based on the determined boiling point temperature.
A vehicle brake alarm, comprising: a first alarm control unit that issues a first alarm when the temperature detected by the temperature detecting means is equal to or higher than the alarm threshold temperature set by the alarm threshold temperature setting unit. apparatus. 1. The first aspect of the present invention is further comprising a bubble detecting means for detecting bubbles generated in the brake fluid and a second alarm control unit for issuing a second alarm when the generation of bubbles is detected by the bubble detecting means. The vehicle brake alarm device described in. The vehicle brake alarm device according to claim 2, wherein the second alarm control unit issues the second alarm in addition to the first alarm by the first alarm control unit. The water content detecting means is installed in a reserve tank in which the brake fluid is injected and the brake fluid is stored at a position where the brake fluid is immersed in the stored brake fluid. The vehicle brake alarm device according to any one of claims 1 to 3. The vehicle brake alarm device according to claim 2 or 3, wherein the bubble detecting means and the temperature detecting means are provided immediately before the brake caliper to which the brake pipe is connected. The boiling point temperature map measures the bubble detection temperature corresponding to the water content of the brake fluid as the boiling point temperature for each type of brake fluid by a test in advance, and the water content contained in the brake fluid for each type of brake fluid. The vehicle brake alarm device according to claim 1, wherein the vehicle brake alarm device is created by a boiling point temperature map creating means for setting a relationship between the temperature and the boiling point temperature.

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