| 摘要 |
A thermostatic expansion valve for a vehicle air-conditioning system includes a valve body with a condenser passage and an evaporator passage, and a power element supported on one end of the body. The power element includes a diaphragm and a pressure pad disposed against the lower surface of the diaphragm. The pressure pad includes a valve stem engaging a valve assembly in the valve body to control the flow of refrigerant between the condenser and evaporator. The valve assembly includes i) a plunger retainer threadably received in the condenser passage, ii) a plunger moveably connected to the plunger retainer and having a throttling member controlling the flow through an orifice in the metering passage, and iii) a spring extending between the plunger retainer and the plunger and biasing the plunger, and hence the throttling member, toward the orifice. The plunger includes a stem with an annular catch at the distal end; while the plunger retainer includes a pair of fingers with catch devices at their distal ends. The catch device of the stem and the catch devices of the plunger retainer prevent the plunger, plunger retainer and spring from being easily disassembled. A valve stem extends downwardly from the diaphragm through an internal bore in the valve body into the metering passage and engages the valve assembly. The movement of the diaphragm in the diaphragm chamber controls the movement of the throttling member of the valve assembly and hence controls the flow through the expansion valve.
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