Patent ID: 9511797
Filing Date: 2016-12-06
CPC Classification: B62D,F16K

Claim Text:
1. An integral power steering device comprising: a housing constructed by a gear housing formed of a metallic material and configured to be closed at one axial end and to have an opening at the other axial end, and a valve housing formed of a metallic material and configured to close the opening end of the gear housing and to have a shaft insertion hole axially formed through the valve housing; a steering shaft adapted to be linked at one end to a steering wheel, the other end of the steering shaft being configured to be inserted into the valve housing so as to face an internal space of the gear housing; a piston linked to the other end of the steering shaft and configured to partition the internal space of the gear housing into a first pressure chamber and a second pressure chamber; a first motion converter interposed between the steering shaft and the piston for converting rotary motion of the steering shaft into axial movement of the piston; a second motion converter configured to be meshed-engagement with a toothed portion formed on an outer periphery of the piston for converting the axial movement of the piston into rotary motion for turning; a rotary valve provided to be linked to the steering shaft in the shaft insertion hole and adapted to selectively introduce working oil supplied from an external hydraulic pressure source to either of the first pressure chamber and the second pressure chamber depending on a rotation direction of the steering shaft; a first valve disposed in the valve housing and configured to discharge hydraulic pressure in the second pressure chamber into the first pressure chamber when the piston has reached a first predetermined stroke position at which a volume of the first pressure chamber becomes a minimum permissible capacity by a movement of the piston; and a second valve disposed in the gear housing and configured to discharge hydraulic pressure in the first pressure chamber into the second pressure chamber when the piston has reached a second predetermined stroke position at which a volume of the second pressure chamber becomes a minimum permissible capacity by a movement of the piston, wherein at least the first valve comprises: a first valve accommodation hole formed by machining the valve housing itself; a first valve seat portion disposed in the first valve accommodation hole and arranged on a side of the first pressure chamber and having a first pin insertion hole axially formed through the first valve seat portion; a first valve element arranged to be opposed to the first valve seat portion and installed to axially slide in the first valve accommodation hole and configured to cut off a movement of working oil from the second pressure chamber to the first pressure chamber with the first valve element seated on the first valve seat portion; a first pin portion integrally connected to the first valve element and configured to face an internal space of the first pressure chamber through the first pin insertion hole and to apply a moving force to the first valve element by pushing the first pin portion by the piston immediately when the first predetermined stroke position of the piston has been reached; and a first biasing member configured to bias the first valve element toward the first valve seat portion.