Road surface condition detecting and anti-skid controlling device in car

A road surface condition detecting device in a car comprising:

• car wheel rotational speed detecting means for detecting rotational speed of a car wheel of said car;
• changing rate detecting means for detecting a speed changing rate of the car wheel rotational speed detected with said car wheel rotational speed detecting means;
• integrating means for integrating an absolute value of the speed changing rate detected with said changing rate detecting means;
• car speed detecting means for detecting car speed;
• speed comparing means for comparing said car wheel rotation speed with said car speed;
• judgment comparing means for comparing an integrated value of said integrating means with a set value for road surface condition judgment to thereby detect a road surface condition;
• and
• memory means for storing judgment information of said judgment comparing means at a time when said speed comparing means detects that said car wheel rotational speed is within a range of being substantially equal to said car speed.

Anti-skid control device comprising:

• a brake pressure source for generating a high pressure and a low pressure;
• valve means which is interposed between said brake pressure source and a car wheel brake, for connecting a liquid flow path between said car wheel brake and said high pressure and low pressure of said brake pressure source;
• car wheel rotation speed detecting means for detecting rotational speed of a car wheel equipped with said car wheel brake;
• calculating means for calculating car speed on the basis of said car wheel rotation speed;
• means for calculating a speed changing rate of said car wheel rotation speed;
• integrating means for integrating an absolute value of the speed changing rate;
• comparing means for comparing an integrated value of said integrating means with a set value for road surface condition judgment;
• and
• brake pressure control means for controlling low pressure/high pressure connection of said car wheel brake by driving said valve means in response to a compared result of said car wheel rotation speed and said car speed and said comparing means.