White Paper: Automotive
Discrete Proportional Valve Technology
Control valves for fluid management should ideally be capable of zero hysteresis, zero steady-state power, a leak-free off state, and a fail-safe condition in the event of power loss. Extant valves, such as rotary valves that are actuated by a stepper motor, do not include all these attributes. While they are capable of zero steady-state power, hysteresis is not truly zero, and the valve will remain in the last commanded position if power is lost.
The Discrete Proportional Valve (DPV technology) incorporates all the desired attributes and overcomes the limitations of extant solutions. The DPV uses two or more binary (on/off) valves of differing flow coefficients in a single manifold, actuated in a specific combination, to achieve a stepped approximation of linear flow.
The need for steady-state power can be eliminated by incorporating a latching solenoid design into the valve actuator. In the latching design, permanent magnets are used to hold the solenoid in the latched position without power, and a reverse-polarity pulse is used to release the valve. The only power used by the DPV is the short pulse needed to change state.
The DPV achieves zero hysteresis because a given command will always result in the same valve members opening in the same combination. This means the flow coefficient is always the same regardless of whether the rate of flow is being increased or decreased.
Finally, a fail-safe condition is easily achieved with the use of a control board that includes a capacitor. In the event of power loss, the capacitive charge is used to actuate the valve system to the desired fail-safe state.
Discrete Proportional Valve solutions are ideally suited for a variety of fluid management applications. They are energy efficient, and the stepped approximation of linear flow provides repeatable fluid control.
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