JP6248319B2 - Vehicle brake negative pressure securing device - Google Patents

Description

  The present invention relates to a brake negative pressure securing device for a vehicle equipped with a brake booster.

  2. Description of the Related Art Conventionally, a vehicle including a brake booster that reduces a depressing force of a brake pedal by using a negative pressure generated in an intake passage of an engine is known.

JP 2008-208729 A JP 2005-264874 A

  In recent years, further improvement in fuel efficiency of the engine has been desired, and with the improvement in fuel efficiency, the engine has become a specification that makes it difficult for negative pressure to occur in the intake passage even during idling. There is a risk that the negative pressure on will become insufficient.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a brake negative pressure securing device for a vehicle that can secure a negative pressure to a brake booster.

A vehicle brake negative pressure securing device according to a first aspect of the present invention for solving the above problems
A brake booster in which negative pressure generated in the intake passage of the engine is introduced;
An alternator that generates electric power from the engine;
A battery for storing electric power generated by the alternator;
An air conditioner that operates with electric power stored in the battery;
Negative pressure value detecting means for detecting a negative pressure value of the brake booster;
Charge amount detecting means for detecting the charge amount of the battery;
Temperature difference detecting means for detecting a temperature difference between a target indoor temperature and an actual indoor temperature of the air conditioner;
The alternator and control means for controlling on / off of the air conditioner;
The control means includes
When the negative pressure value detected by the negative pressure value detecting means is less than a predetermined threshold value, the first negative pressure value generated in the intake passage when the alternator is turned off is obtained, and the air conditioner is turned off. A second negative pressure value that is sometimes generated in the intake passage, the first negative pressure value is greater than or equal to the threshold value, and the second negative pressure value is greater than or equal to the threshold value, Based on the charge amount detected by the charge amount detection means and the temperature difference detected by the temperature difference detection means, it is determined whether to turn off the alternator or the air conditioner ,
When the charge amount detected by the charge amount detection means is within a predetermined charge amount range and the temperature difference detected by the temperature difference detection means is greater than or equal to a predetermined temperature difference threshold, priority is given to turning off the alternator. , When the charge amount is within the predetermined charge amount range and the temperature difference is smaller than the predetermined temperature difference threshold, priority is given to turning off the air conditioner,
A plurality of the charge amount ranges are set by dividing the chargeable amount of the battery,
The temperature difference threshold value is set according to a plurality of the charge amount ranges, and is set to be larger as the charge amount range value is smaller.
When the charge amount is within a first charge amount range among the plurality of charge amount ranges, a first set according to the first charge amount range among the temperature difference and the temperature difference threshold value. When the temperature difference is equal to or greater than the first temperature difference threshold, the alternator is turned off to maintain the operation of the air conditioner, and the temperature difference is the first temperature difference. When the value is smaller than the threshold value, the alternator is operated to turn off the air conditioner.
When the charge amount is smaller than the first charge amount range, the charge amount and a second charge amount range set lower than the first charge amount range among the plurality of charge amount ranges. In comparison, when the charge amount is within the second charge amount range, the temperature difference and a second temperature difference threshold value set larger than the first temperature difference threshold value among the temperature difference threshold values, When the temperature difference is equal to or greater than the second temperature difference threshold value, the alternator is turned off to maintain the operation of the air conditioner. When the temperature difference is smaller than the second temperature difference threshold value, The operation of the alternator is maintained and the air conditioner is turned off .

A brake negative pressure securing device for a vehicle according to a second invention that solves the above problems
In the brake vacuum retention device for a vehicle according to the first aspect,
The control means includes
When both the first negative pressure value and the second negative pressure value are less than the threshold value, both the alternator and the air conditioner are turned off.

  According to the present invention, negative pressure to the brake booster can be ensured, and cooling performance can be ensured as much as possible.

It is a schematic structure figure showing an example of an embodiment of a brake negative pressure securing device of vehicles concerning the present invention. It is a flowchart explaining the control in the brake negative pressure ensuring apparatus of the vehicle shown in FIG. FIG. 3 is a diagram for explaining the flowchart shown in FIG. 2, and is a map diagram showing a relationship among an engine speed, an intake manifold negative pressure, and an engine torque. FIG. 3 is a diagram for explaining the flowchart shown in FIG. 2, and is a map diagram showing a relationship among an engine speed, a generated current (electric power), and an alternator load torque. It is a figure explaining the flowchart shown in FIG. 2, and is a map figure which shows the relationship between an engine speed, a refrigerant pressure, and an air-conditioner load torque.

  Hereinafter, an embodiment of a vehicle brake negative pressure securing device according to the present invention will be described with reference to FIGS.

  FIG. 1 is a schematic configuration diagram illustrating a vehicle brake negative pressure securing device according to the present embodiment, and FIG. 2 is a flowchart illustrating control in the vehicle brake negative pressure securing device illustrated in FIG. 1. 3 to 5 are diagrams for explaining the flowchart shown in FIG. 2. FIG. 3 is a map diagram showing the relationship among the engine speed, intake manifold negative pressure, and engine torque. FIG. FIG. 5 is a map diagram showing the relationship among the engine speed, the refrigerant pressure, and the air conditioner load torque, and FIG. 5 is a map diagram showing the relationship between the rotational speed, the generated current (electric power), and the alternator load torque.

  In the vehicle brake negative pressure securing device of this embodiment, the vehicle is provided with a brake booster 10. The brake booster 10 is divided into a first chamber 12 and a second chamber 13 by a diaphragm 11. And the downstream side of the throttle valve 18 of the intake passage 17 of the engine 16 is connected to the first chamber 12 by the connecting pipe 19, and the negative pressure generated in the intake passage 17 is introduced into the first chamber 12. . Further, a check valve (check valve) 20 is provided in the middle of the connecting pipe 19, thereby preventing a back flow of the negative pressure led to the first chamber 12.

  With such a configuration, the negative pressure generated in the intake passage 17 of the engine 16 when the brake pedal 14 is not depressed is passed through the check valve 20 to the first chamber 12 and the second chamber 13 of the brake booster 10. Guide the first chamber 12 and the second chamber 13 to a negative pressure equal to or higher than a predetermined threshold. Generally, when the engine torque is small (for example, when idling), that is, when the throttle valve 18 is closed, a large negative pressure is likely to be generated. The negative pressure value of the brake booster 10 is detected by a negative pressure sensor 21 (negative pressure value detecting means) provided on the brake booster 10 side from the check valve 20 of the connecting pipe 19.

  When the brake pedal 14 is depressed, the atmospheric pressure is introduced only into the second chamber 13, and the difference between the atmospheric pressure in the second chamber 13 and the negative pressure in the first chamber 12 acts as a brake assist force. Thus, the brake 15 of the vehicle is operated while reducing the depression force of the brake pedal 14.

  The vehicle also includes an alternator (generator) 22 that generates electric power using the power of the engine 16 and a battery 23 that stores electric power generated by the alternator 22. The electric power generated by the alternator 22 and the battery 23 are provided. The electric power stored in is used for the operation of an electrical component provided in the vehicle, for example, an air conditioner (hereinafter A / C) 24. For this A / C 24, a room temperature switch 27 for setting a target room temperature and a room temperature sensor 28 for detecting the actual room temperature are also provided. In this embodiment, the temperature difference between the target room temperature set by the room temperature switch 27 and the actual room temperature detected by the room temperature sensor 28 is detected (temperature difference detection means).

  An ECU (Electronics Control Unit) 25, which is provided in the vehicle and serves as a control means, controls on / off of the alternator 22 and the A / C 24 in accordance with the control described later. At this time, the ECU 25 not only generates a negative pressure value from the negative pressure sensor 21 but also generates a current (electric power) in the alternator 22, an SOC (State of Charge) of the battery 23, and a refrigerant pressure of the A / C 24. , The required level of the cooling performance for A / C 24 (for example, the above-described temperature difference), the operating state of the engine 16 (engine speed, intake manifold negative pressure), and the like are detected. Regarding the SOC of the battery 23, the ECU 25 may directly detect the voltage of the battery 23 to calculate the SOC, or an SOC detection device is provided, and the ECU 25 detects the SOC via the device. (Charge amount detection means).

  Next, the control in the brake negative pressure securing device for a vehicle according to the present embodiment will be described with reference to the flowcharts of FIGS.

(Step S1)
The ECU 25 detects the negative pressure value of the brake booster 10 using the negative pressure sensor 21. If the negative pressure value is equal to or greater than the threshold value, the ECU 25 returns to the start, and if it is less than the threshold value, the process proceeds to step S2.

(Step S2)
When the detected negative pressure value is less than the threshold value, the generated negative pressure when the alternator 22 and the A / C 24 are turned off is calculated.

Here, the calculation of the generated negative pressure generated in the intake passage 17 when the alternator 22 is turned off will be described with reference to the map diagrams of FIGS. As shown in FIG. 3, the engine torque of the engine 16 can be determined from a map of the engine speed and the intake manifold negative pressure. Further, as shown in FIG. 4, the load torque of the alternator 22 can be obtained from a map diagram of the engine speed of the engine 16 and the generated current (electric power) of the alternator 22. Therefore, the change value (decrease value) of the load torque when the alternator 22 is turned off can be obtained from the map diagram of FIG. Then, in FIG. 3, the current engine speed and current operating point obtained from the intake manifold negative pressure when the P _ON, the torque of the operating point P _ON, Subtracting change value of the load torque determined in Figure 4 The operating point P _OFF when the alternator 22 is turned off can be obtained, and the negative pressure at the operating point P _OFF becomes the generated negative pressure (first negative pressure value) when the alternator 22 is turned off.

Similarly, calculation of the generated negative pressure generated in the intake passage 17 when the A / C 24 is turned off will be described with reference to the map diagrams of FIGS. 3 and 5. FIG. 3 is as described above. As shown in FIG. 5, the load torque of A / C 24 can be obtained from a map of the engine speed of engine 16 and the refrigerant pressure of A / C 24. Therefore, the change value (decrease value) of the load torque when A / C 24 is turned off can be obtained from the map diagram of FIG. In FIG. 3, when the current operating point is P _ON , the operating point P when A / C 24 is turned off is obtained by subtracting the change value of the load torque obtained in FIG. 5 from the torque at the operating point P _ON . _OFF can be obtained, and the negative pressure at the operating point P _OFF becomes the generated negative pressure (second negative pressure value) when the A / C 24 is off.

(Step S3)
It is determined whether the calculated negative pressure when the alternator 22 is off can ensure a negative pressure equal to or higher than the threshold value. If it can be ensured, the process proceeds to step S7. If not, the process proceeds to step S4.

(Step S4)
If the generated negative pressure when the alternator 22 is off cannot secure a negative pressure higher than the threshold, it is further determined whether or not the calculated negative pressure generated when the A / C 24 is off can ensure a negative pressure higher than the threshold. Advances to step S6, and if it cannot be secured, advances to step S5.

(Step S5)
When the negative pressure exceeding the threshold cannot be secured with the generated negative pressure when the alternator 22 is off, and when the negative pressure exceeding the threshold cannot be secured even with the generated negative pressure when the A / C 24 is off, that is, the alternator 22 is turned off alone. This is a case where a negative pressure equal to or higher than the threshold cannot be secured, and a negative pressure equal to or higher than the threshold cannot be secured even when the A / C 24 alone is turned off. In such a case, both the alternator 22 and the A / C 24 are turned off to ensure a negative pressure equal to or higher than the threshold value and return to the start. In order to secure a negative pressure equal to or higher than the threshold, it is sufficient that the time for turning off both the alternator 22 and the A / C 24 is about several seconds to several tens of seconds. Although it seems that turning off both the alternator 22 and the A / C 24 is usually small, in order to ensure the performance of the brake 15 relating to safety, in such a case, the alternator 22 and the A / C 24 are unconditionally possible. Both C24 are turned off.

(Step S6)
When the negative pressure exceeding the threshold cannot be secured by the generated negative pressure when the alternator 22 is off, and when the negative pressure exceeding the threshold can be secured by the generated negative pressure when the A / C 24 is off, that is, when the alternator 22 is off alone If the negative pressure above the threshold cannot be secured, but if the negative pressure above the threshold can be secured by turning off the A / C 24 alone, only the A / C 24 is turned off and the process returns to the start. In order to secure a negative pressure equal to or higher than the threshold, it is sufficient that only the A / C 24 is turned off for several seconds to several tens of seconds.

(Step S7)
When the negative pressure exceeding the threshold can be secured by the generated negative pressure when the alternator 22 is off, and further, it is determined whether the negative pressure exceeding the threshold can be secured by the generated negative pressure when the A / C 24 is off, and when it can be secured In step S8, the process proceeds to step S15.

(Step S8)
If the generated negative pressure when the alternator 22 is off can ensure a negative pressure equal to or higher than the threshold, and if the generated negative pressure when the A / C 24 is off can ensure a negative pressure equal to or higher than the threshold, the ECU 25 further If the SOC of the battery 23 is detected and the SOC is greater than 95% of the chargeable amount of the battery 23 (first charge amount threshold), the process proceeds to step S15, and if it is 95% or less, the process proceeds to step S9.

(Step S9)
If the SOC is 95% or less, the process proceeds to step S10 if the SOC is greater than 90% (second charge amount threshold <first charge amount threshold), and if the SOC is 90% or less, the process proceeds to step S11.

(Step S10)
If the SOC is 95% or less and greater than 90%, the ECU 25 further calculates a temperature difference from the target room temperature at the room temperature switch 27 and the actual room temperature by the room temperature sensor 28, and the temperature difference is 3 If it is smaller than ° C. (first temperature difference threshold), the process proceeds to step S16, and if it is 3 ° C. or higher, the process proceeds to step S15.

(Step S11)
If the SOC is 90% or less, the process proceeds to step S12 if the SOC is greater than 85% (third charge amount threshold <second charge amount threshold), and if the SOC is 85% or less, the process proceeds to step S13.

(Step S12)
If the SOC is 90% or less and greater than 85%, and if the temperature difference is smaller than 5 ° C. (second temperature difference threshold> first temperature difference threshold), the process proceeds to step S16, and 5 ° C. or more. If so, the process proceeds to step S15.

(Step S13)
When the SOC is 85% or less, if the SOC is larger than 80% (fourth charge amount threshold <the third charge amount threshold), the process proceeds to step S14, and if it is 80% or less, the process proceeds to step S16.

(Step S14)
If the SOC is 85% or less and greater than 80%, and if the temperature difference is smaller than 7 ° C. (third temperature difference threshold> second temperature difference threshold), the process proceeds to step S16, where 7 ° C. or more. If so, the process proceeds to step S15.

(Step S15)
In the following cases, only the alternator 22 is turned off and the process returns to the start. In order to secure a negative pressure equal to or higher than the threshold, it is sufficient that only the alternator 22 is turned off for several seconds to several tens of seconds.

“Step S7 → Step S15”
This is a case where a negative pressure equal to or higher than the threshold value can be secured with the generated negative pressure when the alternator 22 is off, and a negative pressure equal to or higher than the threshold value cannot be secured with the generated negative pressure when the A / C 24 is off. That is, when the A / C 24 alone is off, a negative pressure equal to or higher than the threshold value cannot be secured, but when the alternator 22 is off alone, a negative pressure equal to or higher than the threshold value can be secured, so only the alternator 22 is turned off.

“Step S8 → Step S15”
This is a case where a negative pressure equal to or higher than the threshold value can be secured with the generated negative pressure when the alternator 22 is off, and a negative pressure equal to or higher than the threshold value can be secured with the generated negative pressure when the A / C 24 is off. This is a case where it is larger than 95% of the chargeable amount of the battery 23, that is, a case where it is within the first charge amount range. That is, the negative pressure above the threshold can be secured even when the alternator 22 is off alone, and the negative pressure above the threshold can be secured even when the A / C 24 alone is off. In this case, since the SOC> 95%, the alternator The operation of A / C 24 is prioritized over 22, and the alternator 22 is prioritized and turned off.

“Step S10 → Step S15”
This is a case where a negative pressure equal to or higher than the threshold value can be secured with the generated negative pressure when the alternator 22 is off, and a negative pressure equal to or higher than the threshold value can be secured with the generated negative pressure when the A / C 24 is off, 95% ≧ SOC> 90% (SOC is in the second charge amount range) and the temperature difference is 3 ° C. (first temperature difference threshold) or more. That is, the negative pressure above the threshold can be secured even when the alternator 22 is off alone, and the negative pressure above the threshold can be secured even when the A / C 24 alone is off. In this case, 95% ≧ SOC> 90%. Since the temperature difference is 3 ° C. or more, the operation of the A / C 24 is prioritized over the alternator 22, and the alternator 22 is turned off with priority.

“Step S12 → Step S15”
This is a case where a negative pressure equal to or higher than the threshold can be secured with the generated negative pressure when the alternator 22 is off, and a negative pressure equal to or higher than the threshold can be secured with the generated negative pressure when the A / C 24 is off, 90% ≧ SOC> 85% (SOC is in the third charge amount range) and the temperature difference is 5 ° C. (second temperature difference threshold) or more. That is, the negative pressure above the threshold can be secured even when the alternator 22 is off alone, and the negative pressure above the threshold can be secured even when the A / C 24 alone is off. In this case, 90% ≧ SOC> 85%. Since the temperature difference is 5 ° C. or more, the operation of the A / C 24 is prioritized over the alternator 22 and the alternator 22 is turned off with priority.

“Step S14 → Step S15”
It is a case where a negative pressure equal to or higher than the threshold value can be secured with the generated negative pressure when the alternator 22 is off, and a negative pressure equal to or higher than the threshold value can be secured with the generated negative pressure when the A / C 24 is off, 85% ≧ SOC> 80% (SOC is in the fourth charge amount range) and the temperature difference is 7 ° C. (third temperature difference threshold) or more. That is, the negative pressure above the threshold can be secured even when the alternator 22 is off alone, and the negative pressure above the threshold can be secured even when the A / C 24 alone is off. In this case, 85% ≧ SOC> 80%. Since the temperature difference is 7 ° C. or more, the operation of the A / C 24 is prioritized over the alternator 22, and the alternator 22 is prioritized and turned off.

  As described above, in steps S9 to S14, when the temperature difference is large, in other words, when the cooling performance requirement level is high and the cooling performance is required, the alternator 22 is preferentially turned off, and the operation of the A / C 24 is performed. Has priority. Also, when the SOC of the battery 23 is sufficiently high, there is no problem even if the alternator 22 is turned off, so the alternator 22 is turned off with priority.

(Step S16)
In the following cases, only A / C 24 is turned off and the process returns to the start. In order to secure a negative pressure equal to or higher than the threshold, it is sufficient that only the A / C 24 is turned off for several seconds to several tens of seconds.

“Step S10 → Step S16”
This is a case where a negative pressure equal to or higher than the threshold value can be secured with the generated negative pressure when the alternator 22 is off, and a negative pressure equal to or higher than the threshold value can be secured with the generated negative pressure when the A / C 24 is off, 95% ≧ SOC> 90% (SOC is in the second charge amount range) and the temperature difference is less than 3 ° C. (first temperature difference threshold). That is, the negative pressure above the threshold can be secured even when the alternator 22 is off alone, and the negative pressure above the threshold can be secured even when the A / C 24 alone is off. In this case, 95% ≧ SOC> 90%. Since the temperature difference is less than 3 ° C., even if the operation of the A / C 24 is stopped, the influence on the driver is small, so the A / C 24 is preferentially turned off.

“Step S12 → Step S16”
This is a case where a negative pressure equal to or higher than the threshold can be secured with the generated negative pressure when the alternator 22 is off, and a negative pressure equal to or higher than the threshold can be secured with the generated negative pressure when the A / C 24 is off, 90% ≧ SOC> 85% (SOC is within the third charge amount range) and the temperature difference is less than 5 ° C. (second temperature difference threshold). That is, the negative pressure above the threshold can be secured even when the alternator 22 is off alone, and the negative pressure above the threshold can be secured even when the A / C 24 alone is off. In this case, 90% ≧ SOC> 85%. In addition, since the temperature difference is less than 5 ° C., even if the operation of the A / C 24 is stopped, the influence on the driver is small, so the A / C 24 is preferentially turned off.

“Step S14 → Step S16”
It is a case where a negative pressure equal to or higher than the threshold value can be secured with the generated negative pressure when the alternator 22 is off, and a negative pressure equal to or higher than the threshold value can be secured with the generated negative pressure when the A / C 24 is off, 85% ≧ SOC> 80% (SOC is in the fourth charge amount range) and the temperature difference is less than 7 ° C. (third temperature difference threshold). That is, the negative pressure above the threshold can be secured even when the alternator 22 is off alone, and the negative pressure above the threshold can be secured even when the A / C 24 alone is off. In this case, 85% ≧ SOC> 80%. In addition, since the temperature difference is less than 7 ° C., even if the operation of the A / C 24 is stopped, the influence on the driver is small, so the A / C 24 is preferentially turned off.

“Step S13 → Step S16”
This is a case where a negative pressure equal to or higher than the threshold value can be secured with the generated negative pressure when the alternator 22 is off, and a negative pressure equal to or higher than the threshold value can be secured with the generated negative pressure when the A / C 24 is off. ≧ SOC (SOC is in the fifth charge amount range). That is, the negative pressure above the threshold can be secured even when the alternator 22 is off alone, and the negative pressure above the threshold can be secured even when the A / C 24 alone is off. In this case, since 80% ≧ SOC, the battery 23, giving priority to charging, that is, giving priority to the operation of the alternator 22 over A / C 24 and turning off A / C 24.

  As described above, in steps S9 to S14, when the temperature difference is small, in other words, when the cooling performance requirement level is low, the operation of the alternator 22 is prioritized by turning off the A / C 24 with priority. Further, when the SOC of the battery 23 is low, the battery 23 needs to be charged. Therefore, the alternator 22 is operated with priority and the A / C 24 is turned off with priority.

  As described above, in steps S8 to S14, a plurality of charge amount ranges (first to fifth charge amount ranges) are set for the chargeable amount of the battery 23, and a plurality of temperature differences are also set. Temperature difference threshold values (first to third temperature difference threshold values) are set. At this time, the temperature difference threshold value is set according to a plurality of charge amount ranges, and is set to be larger as the charge amount range value is smaller. Then, when the detected SOC is larger than the predetermined temperature difference threshold set in the corresponding charge amount range, priority is given to turning off the alternator 22. In this way, it is determined which of the alternator 22 and the A / C 24 is turned off preferentially based on the temperature difference (the level of the cooling performance requirement level) and the SOC level. In this embodiment, the higher the SOC is, the higher priority is given to turning off the alternator 22, and the higher the temperature difference is, the higher priority is given to turning off the A / C 24. However, the first to fifth charge amount ranges (first By appropriately setting the first to third temperature difference threshold values and the first to third temperature difference threshold values, the alternator 22 is preferentially turned off over the A / C 24 to suppress load torque due to power generation. .

  In the flowchart of FIG. 2, the predetermined temperature difference threshold for the first charge amount range and the fifth charge amount range is not set. However, if it is set, for example, the first charge amount range has a predetermined threshold value. The temperature difference threshold is 0 ° C., and the predetermined temperature difference threshold is ∞ ° C. in the fifth charge amount range. In the first charge amount range, it is not necessary to turn off the A / C 24 when the temperature difference threshold is less than 0 ° C., and in the fifth charge amount range, the temperature difference threshold becomes ∞ ° C. or more. And the alternator 22 is not turned off. In other words, there is no difference in control whether or not the predetermined temperature difference threshold for the first charge amount range and the fifth charge amount range is set. Therefore, the predetermined temperature difference threshold is shown in the flowchart of FIG. Is not specified.

  The present invention is suitable for a vehicle equipped with a brake booster.

10 Brake Booster 16 Engine 21 Negative Pressure Sensor 22 Alternator 23 Battery 24 Air Conditioner (A / C)
25 ECU
27 Room temperature switch 28 Room temperature sensor

Claims (2)

A brake booster in which negative pressure generated in the intake passage of the engine is introduced;
An alternator that generates electric power from the engine;
A battery for storing electric power generated by the alternator;
An air conditioner that operates with electric power stored in the battery;
Negative pressure value detecting means for detecting a negative pressure value of the brake booster;
Charge amount detecting means for detecting the charge amount of the battery;
Temperature difference detecting means for detecting a temperature difference between a target indoor temperature and an actual indoor temperature of the air conditioner;
The alternator and control means for controlling on / off of the air conditioner;
The control means includes
When the negative pressure value detected by the negative pressure value detecting means is less than a predetermined threshold value, the first negative pressure value generated in the intake passage when the alternator is turned off is obtained, and the air conditioner is turned off. A second negative pressure value that is sometimes generated in the intake passage, the first negative pressure value is greater than or equal to the threshold value, and the second negative pressure value is greater than or equal to the threshold value, Based on the charge amount detected by the charge amount detection means and the temperature difference detected by the temperature difference detection means, it is determined whether to turn off the alternator or the air conditioner ,
When the charge amount detected by the charge amount detection means is within a predetermined charge amount range and the temperature difference detected by the temperature difference detection means is greater than or equal to a predetermined temperature difference threshold, priority is given to turning off the alternator. , When the charge amount is within the predetermined charge amount range and the temperature difference is smaller than the predetermined temperature difference threshold, priority is given to turning off the air conditioner,
A plurality of the charge amount ranges are set by dividing the chargeable amount of the battery,
The temperature difference threshold value is set according to a plurality of the charge amount ranges, and is set to be larger as the charge amount range value is smaller.
When the charge amount is within a first charge amount range among the plurality of charge amount ranges, a first set according to the first charge amount range among the temperature difference and the temperature difference threshold value. When the temperature difference is equal to or greater than the first temperature difference threshold, the alternator is turned off to maintain the operation of the air conditioner, and the temperature difference is the first temperature difference. When the value is smaller than the threshold value, the alternator is operated to turn off the air conditioner.
When the charge amount is smaller than the first charge amount range, the charge amount and a second charge amount range set lower than the first charge amount range among the plurality of charge amount ranges. In comparison, when the charge amount is within the second charge amount range, the temperature difference and a second temperature difference threshold value set larger than the first temperature difference threshold value among the temperature difference threshold values, When the temperature difference is equal to or greater than the second temperature difference threshold value, the alternator is turned off to maintain the operation of the air conditioner. When the temperature difference is smaller than the second temperature difference threshold value, A brake negative pressure securing device for a vehicle , wherein the operation of the alternator is maintained and the air conditioner is turned off . The brake negative pressure securing device for a vehicle according to claim 1 ,
The control means includes
A brake negative pressure securing device for a vehicle, wherein both the alternator and the air conditioner are turned off when both the first negative pressure value and the second negative pressure value are less than the threshold value.

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