Master cylinder
First Claim
Patent Images
1. A master cylinder comprising:
- a piston disposed in a cylindrical bore formed in a body for moving freely in forward and rearward directions;
a pressure generating chamber and a supply chamber formed in the body, the pressure generating chamber being separated from the supply chamber by the piston, the pressure generating chamber communicating with an output port and the supply chamber communicating with a reservoir storing brake fluid;
said piston discharging brake fluid of increased pressure in said pressure generating chamber to said output port upon operation of said piston, and said piston being returned to a non-operating position by a return spring arranged within said pressure generating chamber;
said piston having an opening portion communicating said supply chamber with said pressure generating chamber, said piston having an axis;
a rod positioned within said opening portion, said rod including an axially extending hole;
said supply chamber and said pressure generating chamber being communicated by a flow passage formed between an inner periphery of the opening portion of said piston and an outer periphery of said rod when said piston is positioned in the non-operating position;
said flow passage being closed by a seal member arranged on the outer periphery of said rod when said piston moves a predetermined distance; and
a check valve positioned within said piston along the axis of the piston for communicating said supply chamber with said pressure generating chamber only when said piston is in the non-operating position and said pressure generating chamber is under negative pressure.
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Abstract
In a master cylinder for drawing brake fluid from a reservoir through a pressure generating chamber in the master cylinder during fluid pressure control to supply brake pressure to a wheel cylinder, a check valve is provided for securing sufficient suction from the master cylinder. The check valve is operational to communicate the supply chamber and the pressure generating chamber with each other only when the pressure generating chamber is under a negative pressure while the piston is in a non-operating position. The check valve is arranged within the inner portion of the piston and along the axis of the piston.
18 Citations
19 Claims
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1. A master cylinder comprising:
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a piston disposed in a cylindrical bore formed in a body for moving freely in forward and rearward directions; a pressure generating chamber and a supply chamber formed in the body, the pressure generating chamber being separated from the supply chamber by the piston, the pressure generating chamber communicating with an output port and the supply chamber communicating with a reservoir storing brake fluid; said piston discharging brake fluid of increased pressure in said pressure generating chamber to said output port upon operation of said piston, and said piston being returned to a non-operating position by a return spring arranged within said pressure generating chamber; said piston having an opening portion communicating said supply chamber with said pressure generating chamber, said piston having an axis; a rod positioned within said opening portion, said rod including an axially extending hole; said supply chamber and said pressure generating chamber being communicated by a flow passage formed between an inner periphery of the opening portion of said piston and an outer periphery of said rod when said piston is positioned in the non-operating position; said flow passage being closed by a seal member arranged on the outer periphery of said rod when said piston moves a predetermined distance; and a check valve positioned within said piston along the axis of the piston for communicating said supply chamber with said pressure generating chamber only when said piston is in the non-operating position and said pressure generating chamber is under negative pressure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A master cylinder comprising:
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a body having a bore in which is positioned an axially movable piston to form a pressure generating chamber on one side of the piston and a supply chamber on an opposite side of piston, the pressure generating chamber being in communication with an output port formed in the body and the supply chamber being in communication with a reservoir storing brake fluid; a return spring operatively associated with said piston for applying an urging force to the piston for normally urging said piston to a non-operating position, the piston being axially movable against the normal urging force of the return spring to an operating position in which brake fluid of increased pressure in said pressure generating chamber is output to said output port; a check valve positioned within said piston for permitting communication between said supply chamber and said pressure generating chamber only when said piston is in the non-operating position and said pressure generating chamber is under negative pressure; and an axially movable rod positioned within the piston, said supply chamber and said pressure generating chamber being communicated by a flow passage formed between said piston and said rod when said piston is positioned in the non-operating position. - View Dependent Claims (11, 12, 18)
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13. A master cylinder comprising:
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a body having a bore in which is positioned an axially movable piston to form a pressure generating chamber on one side of the piston and a supply chamber on an opposite side of piston, the pressure generating chamber being in communication with an output port formed in the body and the supply chamber being in communication with a reservoir storing brake fluid; a return spring operatively associated with said piston for applying an urging force to the piston for normally urging said piston to a non-operating position, the piston being axially movable against the normal urging force of the return spring to an operating position in which brake fluid of increased pressure in said pressure generating chamber is output to said output port; a check valve positioned within said piston for permitting communication between said supply chamber and said pressure generating chamber only when said piston is in the non-operating position and said pressure generating chamber is under negative pressure; and a rod movably positioned within said piston, said rod including an axially extending hole, the communication of said supply chamber with said pressure generating chamber only when said piston is in the non-operating position and said pressure generating chamber is under negative pressure occurring by way of said hole in said rod. - View Dependent Claims (14, 15, 16, 17)
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19. A master cylinder comprising:
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a body having a bore in which is positioned an axially movable piston to form a pressure generating chamber on one side of the piston and a supply chamber on an opposite side of piston, the pressure generating chamber being in communication with an output port formed in the body and the supply chamber being in communication with a reservoir storing brake fluid; a return spring operatively associated with said piston for applying an urging force to the piston for normally urging said piston to a non-operating position, the piston being axially movable against the normal urging force of the return spring to an operating position in which brake fluid of increased pressure in said pressure generating chamber is output to said output port; an axially movable rod positioned within said piston, said rod including an axially extending hole; a flow passage for communicating the pressure generating chamber with the supply chamber when the piston is in the non-operating position; an axially movable valve body positioned within the piston; and a spring member for normally urging the valve body towards the rod to close the hole in the rod, the valve body being movable away from the rod to open the hole in the rod and permit communication between the supply chamber and the pressure generating chamber by way of the hole in the rod only when said piston is in the non-operating position and said pressure generating chamber is under negative pressure.
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Specification