Sizing up flow forces

摘要

Designers of spool-type, solenoid-operated hydraulic valves often face the vexing problem of increasing flow while shrinking the size of the solenoid actuator. It's an effort to boost performance while reducing size, power consumption, and costs. But solving the problem means the inconvenient factor of flow forces must be taken into account. Computing flow forces presents practical engineering problems for two main reasons. First, flow forces are generally not as well understood as, say, pressure forces. Second, the pump and other hydraulic-system components dynamically affect transient flow forces in the valve. So let's Precisel see how the system affects internal forces and overall valve performance. Flow force, sometimes referred to as the Bernoulli force, results from ac-celeration of the fluid mass in the small opening between the valve's spool and sleeve.