An anti-lock brake apparatus, a vehicle, an electric vehicle and an electric-assisted vehicle. The anti-lock brake apparatus is applied to a brake system, and the brake system is used to provide a brake frictional force for a wheel, the brake system includes a brake oil pipeline, and the anti-lock brake apparatus includes: a volume-adjusting part, the volume-adjusting part has a volume chamber, the volume chamber is connected into the brake oil pipeline, a volume of the volume chamber is continuously adjustable, the volume-adjusting part adjusts the volume of the volume chamber according to a state parameter of the wheel, to enable an oil pressure in the brake oil pipeline to vary, and the brake frictional force exerted on the wheel by the brake system is adjustable. The apparatus has high reliability and high brake efficiency.

A vehicle includes a brake system. The brake system includes a hydraulic brake line having a line pressure. The vehicle additionally includes a vacuum reservoir. The vacuum reservoir is selectively fluidly coupled to the hydraulic brake line. The vacuum reservoir is configured to, when fluidly coupled to the hydraulic brake line, reduce the line pressure during a drive cycle.

A vehicle includes a brake system. The brake system includes a hydraulic brake line having a line pressure. The vehicle additionally includes a vacuum reservoir. The vacuum reservoir is selectively fluidly coupled to the hydraulic brake line. The vacuum reservoir is configured to, when fluidly coupled to the hydraulic brake line, reduce the line pressure during a drive cycle.

A valve unit for an anti-lock braking system has a valve body, a piston, and an elastic element acting on the piston. The valve body has an outlet port, an inlet port, a primary chamber communicating with the outlet port, an expansion chamber with an outflow passage establishing fluid communication between the primary chamber and the expansion chamber, and a bypass passage between the inlet port and the outlet port. The piston is movable in the primary chamber and has a longitudinal through cavity, a first transversal surface facing the outlet port, and a second transversal surface facing away from the outlet port. The first transversal surface has an area smaller than the area of the second transversal surface. The elastic element exerts an elastic force to move the piston away from the outlet port. The valve unit is activatable by pressure of a brake fluid in the primary chamber.