| 主权项 |
1. An integral power steering apparatus comprising:
a housing; an input shaft adapted to be connected to a steering wheel; a piston slidably accommodated in the housing and configured to partition an internal space of the housing into a first pressure chamber and a second pressure chamber; a first motion converter interposed between the input shaft and the piston for converting rotary motion of the input shaft into linear motion of the piston; a second motion converter including a rack integrally formed on an outer periphery of the piston and a sector gear kept in meshed-engagement with the rack for converting linear motion of the rack into rotary motion and arranged in the second pressure chamber; a control valve configured to selectively supply working fluid, fed from an external working-fluid pressure source, into either one of the first and second pressure chambers; a motion transmitter adapted to transmit a movement of the sector gear about a rotation axis to a steered road wheel; a first valve configured to direct working-fluid pressure in the second pressure chamber to the first pressure chamber, when the piston reaches a first predetermined position in a direction for decreasing a volumetric capacity of the first pressure chamber; and a second valve configured to direct working-fluid pressure in the first pressure chamber to the second pressure chamber, when the piston reaches a second predetermined position in a direction for decreasing a volumetric capacity of the second pressure chamber; the first valve installed on the housing in such a manner as to face the first pressure chamber, the first valve comprising:
a first valve body having a first plunger-accommodation bore formed therein;a first plunger housed in the first plunger-accommodation bore in such a manner as to retract or extend in a longitudinal direction of the first valve body;a first seat installed on the first valve body in such a manner as to construct a part of a first communication passage through which the first and second pressure chambers can be communicated with each other, and configured to prevent working-fluid flow through the first communication passage with the first plunger abutted on the first seat, and further configured to permit working-fluid flow through the first communication passage with the first plunger moved apart from the first seat;a first biasing member provided for permanently biasing the first plunger toward the first seat;a first abutted-engagement portion attached to the first plunger in such a manner as to protrude from the first seat toward the first pressure chamber, and configured to be brought into abutted-engagement with a first abutment portion corresponding to one end face of the piston when the first predetermined position of the piston is reached, and further configured to move together with the first plunger by a push of the first abutment portion, thereby causing the first plunger to be spaced apart from the first seat to permit the first pressure chamber to be communicated with the second pressure chamber through the first communication passage; anda first valve-position adjuster comprising a first intermediate sleeve formed separately from the housing, and interposed between the housing and the first valve body, and having a first valve-body accommodation bore formed therein for accommodating the first valve body; the second valve installed on the housing in such a manner as to face the second pressure chamber, the second valve comprising:
a second valve body having a second plunger-accommodation bore formed therein;a second plunger housed in the second plunger-accommodation bore in such a manner as to retract or extend in a longitudinal direction of the second valve body;a second seat installed on the second valve body in such a manner as to construct a part of a second communication passage through which the first and second pressure chambers can be communicated with each other, and configured to prevent working-fluid flow through the second communication passage with the second plunger abutted on the second seat, and further configured to permit working-fluid flow through the second communication passage with the second plunger moved apart from the second seat;a second biasing member provided for permanently biasing the second plunger toward the second seat;a second abutted-engagement portion attached to the second plunger in such a manner as to protrude from the second seat toward the second pressure chamber, and configured to be brought into abutted-engagement with a second abutment portion corresponding to either one of the other end face of the piston and the sector gear when the second predetermined position of the piston is reached, and further configured to move together with the second plunger by a push of the second abutment portion, thereby causing the second plunger to be spaced apart from the second seat to permit the second pressure chamber to be communicated with the first pressure chamber through the second communication passage; anda second valve-position adjuster comprising a second intermediate sleeve formed separately from the housing, and interposed between the housing and the second valve body, and having a second valve-body accommodation bore formed therein for accommodating the second valve body, wherein the first valve body of the first valve is configured to enable a position of the first valve body relative to the housing to be adjusted in the longitudinal direction of the first valve body via the first intermediate sleeve, and the second valve body of the second valve is configured to enable a position of the second valve body relative to the housing to be adjusted in the longitudinal direction of the second valve body via the second intermediate sleeve, wherein the first valve body of the first valve has a first valve-body through hole through which the first plunger-accommodation bore and an outer peripheral side of the first valve body are communicated with each other, the first valve-position adjuster has a first valve-position-adjuster through hole configured to communicate on an inner peripheral side of the first valve-position adjuster with the first valve-body through hole and further configured to communicate on an outer peripheral side of the first valve-position adjuster with the second pressure chamber, the second valve body of the second valve has a second valve-body through hole through which the second plunger-accommodation bore and an outer peripheral side of the second valve body are communicated with each other, and the second valve-position adjuster has a second valve-position-adjuster through hole configured to communicate on an inner peripheral side of the second valve-position adjuster with the second valve-body through hole and further configured to communicate on an outer peripheral side of the second valve-position adjuster with the first pressure chamber. |
