Solenoid-operated hydraulic control device for anti-skid brake system

Claim 2

A hydraulic control device for an anti-skid hydraulic brake system having a hydraulic actuator such as a brake cylinder (102) for applying a brake to a wheel of a vehicle or a regulator (128) for regulating a pressure in the brake cylinder (102), the hydraulic control device including a solenoid-operated directional control valve (32) for communication of a pressure chamber in said hydraulic actuator, selectively with a hydraulic power source (100, 114, 116; 122, 126) and a reservoir (112; 120), and further including a solenoid-operated flow control valve (34) disposed between the directional control valve (32) and one of said pressure chamber, said hydraulic power source (100, 114, 116; 122, 126) and said reservoir (112; 120), to control a flow of a fluid in two steps, said hydraulic control device being operated to effect rapid rise and fall and slow rise and/or fall of a pressure in said pressure chamber, in response to a slip ratio of the wheel, said solenoid-operated flow control valve (34) comprising: means for defining a valve hole (88); a valve seat (76) in which said valve hole is open; a valving member (72) movable between its first position in which the valving member (72) is seated on said valve seat (76), and its second position in which the valving member (72) is spaced apart from said valve seat (76); a solenoid (82) which is energized and deenergized for moving said valving member (72) between said first and second positions; and a flow restrictor (86, 168, 188) permitting a predetermined rate of restricted flow of the fluid through a restrictor passage while said valving member (72) is placed in said first position, said predetermined rate of restricted flow being smaller than a rate of flow of the fluid while said valving member (72) is placed in said second position, characterized in that said flow restrictor (86,168, 188) is provided on one of said valve seat (76) and said valving member (72) permitting said predetermined rate of restricted flow of the fluid through said valve hole (88).

Claim 3

A hydraulic control device according to claim 1, wherein said flow restrictor comprises at least one groove (86,188) formed in a contact surface of said one of the valve seat (76) and the valving member (72) when the valving member (72) is placed in said first position.

Claim 4

A hydraulic control device according to claim 1, wherein said flow restrictor comprises one of contact surfaces of said valving member (72) and said valve seat (76) which contact each other while said valving member (72) is placed in said first position, said one contact surface being formed with minute indentations and/or projections which provide gaps between said contact surfaces while the valving member (72) is placed in said first position.

Claim 5

A hydraulic control device according to claim 1, wherein said flow restrictor is constituted by a porous structure (168) which forms at least an end portion of said valving member (72) which contacts said valve seat (76) whilethe valving member (72) is placed in said first position, said porous structure (168) having an infinite number of minute continuous pores.

Claim 6

A hydraulic control device according to claim 4, wherein said porous structure (168) is formed of a sintered alloy.

Claim 7

A hydraulic control device according to claim 1, wherein said valving member (72) is normally placed in said second position to hold said valve fully open.

Claim 8

A hydraulic control device for an anti-skid hydraulic brake system having a hydraulic actuator such as a brake cylinder (102) for applying a brake to a wheel of a vehicle, or a regulator (128) for regulating a pressure in the brake cylinder (102), the hydraulic control device including a solenoid-operated directional control valve (32) for communication of a pressure chamber in said hydraulic actuator, selectively with a hydraulic power source (100, 114, 116; 122, 126) and a reservoir (112; 120), and further including a solenoid-operated flow control valve (170) disposed between the directional control valve (32) and one of said pressure chamber, said hydraulic power source (100, 114, 116; 122, 126) and said reservoir (112; 120) to control a flow of a fluid in two steps by opening and closing a non-restrictor passage, said hydraulic control device being operated to effect rapid rise and fall and slow rise and/or fall of a pressure in said pressure chamber in response to a slip ratio of the wheel, said solenoid-operated flow control valve (170) comprising: means for defining a valve hole (88) in said non-restrictor passage; a valve seat (76) in which said valve hole is open; a valving member (72) movable between its first position in which the valving member (72) is seated on said valve seat (76), and its second position in which the valving member (72) is spaced apart from said valve seat (76); a solenoid (82) which is energized and deenergized for moving said valving member (72) between said first and second positions; and a flow restrictor (172), permitting a predetermined rate of restricted flow of the fluid through a restrictor passage while said valving member (72) is placed in said first position, said predetermined rate of restricted flow being smaller than a rate of flow of the fluid while said valving member (72) is placed in said second position, said flow restrictor (172) comprising a restrictor hole in parallel with said valve hole (88), characterized by a porous structure (176; 178) filling said restrictor hole, and cooperating with said restrictor hole, to define said flow restrictor (172).

Claim 9

A hydraulic control device for an anti-skid hydraulic brake system having a hydraulic actuator such as a brake cylinder (102) for applying a brake to a wheel of a vehicle, or a regulator (128) for regulating a pressure in the brake cylinder (102), the hydraulic control device including a solenoid-operated directional control valve (32) for communication of a pressure chamber in said hydraulic actuator, selectively with a hydraulic power source (100, 114, 116; 122, 126) and a reservoir (112; 120), and further including a solenoid-operated flow control valve (170) disposed between the directional control valve (32) and one of said pressure chamber, said hydraulic power source (100, 114, 116; 122, 126) and said reservoir (112; 120) to control a flow of a fluid in two steps by opening and closing a non-restrictor passage, said hydraulic control device being operated to effect rapid rise and fall and slow rise and/or fall of a pressure in said pressure chamber in response to a slip ratio of the wheel, said solenoid-operated flow control valve (170) comprising: means for defining a valve hole (88) in said non-restrictor passage; a valve seat (76) in which said valve hole is open; a valving member (72) movable between its first position in which the valving member (72) is seated on said valve seat (76), and its second position in which the valving member (72) is spaced apart from said valve seat (76); a solenoid (82) which is energized and deenergized for moving said valving member (72) between said first and second positions; and a flow restrictor (172), permitting a predetermined rate of restricted flow of the fluid through a restrictor passage while said valving member (72) is placed in said first position, said predetermined rate of restricted flow being smaller than a rate of flow of the fluid while said valving member (72) is placed in said second position, said flow restrictor (172) comprising a restrictor hole in parallel with said valve hole (88), characterized by a porous structure (176; 178) filling said restrictor hole, and cooperating with said restrictor hole, to define said flow restrictor (172).

Claim 10

A hydraulic control device according to claim 7, wherein said porous structure (178) is a laminar structure consisting of a central dense layer (180) having fine pores, and a pair of coarse layers (182) which sandwich said central dense layer and have coarse pores of sizes larger than said fine pores, said laminar structure (178) being positioned in said restrictor hole so that the fluid flows in directions substantially perpendicular to said dense layer (180) and coarse layers (182).

Claim 11

A hydraulic control device according to claim 7, wherein said porous structure (176; 178) is formed of a sintered alloy.

Claim 12

A hydraulic control device according to claim 7, wherein said valve hole (88) is normally held open.