Hydraulic brake apparatus for preventing shortage of brake fluid in a master cylinder due to failure of a high pressure source

摘要

A hydraulic brake apparatus maintains a sufficient amount of brake fluid in a master cylinder (12) when a failure occurs in a high pressure brake fluid source (34) which provides a high pressure brake fluid to a wheel cylinder (52). The hydraulic brake apparatus generates a wheel cylinder pressure provided to the wheel cylinder (52) by using a high pressure brake fluid provided by the high pressure brake fluid source (34). The wheel cylinder pressure is controlled in response to a master cylinder pressure generated by the master cylinder (12). A fluid pressure control valve (18), having a spool (58) movable in response to the master cylinder pressure, connects one of the high pressure brake fluid source (34) and a low pressure brake fluid source (22) to the wheel cylinder (52) so that the wheel cylinder pressure is controlled in response to the master cylinder pressure. A low pressure source passage (24) connects the low pressure brake fluid source (22) to the fluid pressure control valve (18) so as to supply a low pressure brake fluid to the fluid pressure control valve (18). A low pressure source passage control valve (28) closes the low pressure source passage (24) when the high pressure brake fluid is not provided to the fluid pressure control valve (18). <IMAGE>