摘要 |
A modulator valve assembly including a housing defining fluid inlet and outlet passages, and a valve member which moves along an axis within the housing, the valve member having first and second positions separated along the axis, and operably disposed between the fluid inlet and outlet passages. The variable size of an opening through which the fluid inlet and outlet passages are in fluid communication within the housing is at least partially defined by the valve member, the opening respectively having first and second sizes when the valve member is in its first and second positions. The axis of rotation of the output of a reversible motor is substantially aligned with the axis along which the valve member moves. The motor output and valve member are operably engaged through relatively rotatable threaded male and female portions of a joint, the threads of the joint male and female portions interengaged. One of the male and female portions is rotatably fixed to the motor output, and the valve member is axially fixed to the other, whereby the valve member is moved axially in response to rotation of the motor output. The threads of the male and female portions each have a first surface that generally faces a first direction and a second surface that generally faces a second, substantially opposite direction. The first thread surface of one of the male and female portions is biased into continuous contact with the second thread surface of the other. |