Patent ID: 8302629
Filing Date: 2012-11-06
Classification: F15B,Y10T

Abstract:
1. A valve unit comprising: a valve housing; a first valve body disposed in the valve housing in a slidable manner; and a second valve body disposed to be slidable with respect to the first valve body, wherein, the valve housing includes: a first passage and a second passage in which pressure fluid flows to slide the second valve body; a pump port connected to a pump; a tank port connected to a tank; and a first cylinder port and a second cylinder port both connected to a cylinder of a hydraulic actuator, and wherein, a combination of a position of the first valve body after sliding and a position of the second valve body after sliding with respect to the first valve body achieves: a first state in which the pump port is connected to the first cylinder port whereas the second cylinder port is connected to the tank port; a second state in which the pump port is connected to the second cylinder port whereas the first cylinder port is connected to the tank port; a third state in which the pump port, the tank port, the first cylinder port, and the second cylinder port are closed; and a fourth state in which the pump port is closed whereas the first cylinder port is connected to the second cylinder port.