Automatic braking control device

1. An automatic braking control device comprising:

a temperature obtaining section for obtaining an index value of a temperature of brake fluid;

a collision prediction time calculation section for calculating collision prediction time of a vehicle with an object;

a collision determination section for determining whether the collision prediction time is less than or equal to a threshold; and

a pressure control section for controlling a start timing of pressurization of the brake fluid when the collision prediction time is less than or equal to the threshold, wherein

the pressure control section sets the start timing of pressurization to a first timing when the index value of the temperature is a first temperature,

the pressure control section sets the start timing of pressurization to a second timing when the index value of the temperature is a second temperature,

the first temperature is lower than the second temperature, and

time from a time point of determination of the collision determination section to the first timing is shorter than time from the time point of determination of the collision determination section to the second timing.

2. The automatic braking control device according to claim 1 , wherein the pressure control section is configured to accelerate the start of pressurization as the temperature of the brake fluid is lowered in a predetermined temperature range.

3. The automatic braking control device according to claim 1 , wherein the temperature obtaining section obtains an ambient temperature as the index value of the temperature of the brake fluid.

4. The automatic braking control device according to claim 1 , further comprising a temperature estimation section that obtains idle time of a motor of a pressure pump for pressurizing the brake fluid, wherein the shorter the idle time, the lower the temperature of the brake fluid estimated by the temperature estimation section becomes, wherein

the idle time is time from supply stop of drive current to the motor to rotation stop of the motor, and

the temperature obtaining section obtains an estimation result of the temperature estimation section as the index value of the temperature of the brake fluid.

5. The automatic braking control device according to claim 1 , wherein the lower the temperature of the brake fluid, the greater becomes the degree of acceleration of the start of pressurization of the brake fluid made by the pressure control section.

6. The automatic braking control device according to claim 1 , wherein

when:

starting time is defined as time to a time point when pressurization of the brake fluid is started with reference to a time point when the collision prediction time has passed; and

reference time for starting is defined as the starting time when the temperature of the brake fluid is at a predetermined reference temperature,

the pressure control section calculates a corrective coefficient having a negative correlation with the temperature of the brake fluid from the temperature of the brake fluid and multiplies the reference time for starting by the corrective coefficient to correct the starting time.

7. An automatic braking control device for a vehicle with an air brake system, the air brake system including a brake chamber, an air tank, and a switch section for switching between supply and supply stop of compressed air from the air tank to the brake chamber, the automatic braking control device comprising:

a pressure obtaining section for obtaining pressure of compressed air within the air tank;

a collision prediction time calculation section for calculating collision prediction time of a vehicle with an object;

a collision determination section for determining whether the collision prediction time is less than or equal to a threshold; and

a switching control section for controlling a start timing of driving of the switch section when the collision prediction time is less than or equal to the threshold, wherein

when the pressure is at a first pressure, the switching control section sets a start timing of supply of the compressed air by driving of the switch section to a first timing,

when the pressure is at a second pressure, the switching control section sets the start timing of the supply of the compressed air by driving of the switch section to a second timing,

the first pressure is lower than the second pressure, and

time from a time point of determination of the collision determination section to the first timing is shorter than time from the time point of determination of the collision determination section to the second timing.

8. The automatic braking control device according to claim 7 , wherein the switching control section is configured to accelerate the start of driving of the switch section in comparison with a case when the pressure of the compressed air is higher than the reference pressure when the pressure of the compressed air is less than or equal to a predetermined reference pressure.

9. The automatic braking control device according to claim 7 , further comprising a relative speed obtaining section for obtaining a relative speed of the vehicle with respect to the object, wherein

the greater the relative speed, the greater becomes the degree of acceleration of driving of the switch section executed by the switching control section.

10. The automatic braking control device according to claim 7 , wherein

the pressure obtaining section obtains a result detected by a pressure detection section for detecting the pressure of the compressed air in the air tank as the pressure of the compressed air in the air tank.

11. The automatic braking control device according to claim 7 , wherein the lower the pressure of the compressed air, the earlier the driving of the switch section is started by the switching control section.