Proportional Valve
Technical Article

TECHNICAL BACKGROUND

Teknocraft’s new breed of solenoid operated, patented proportional valves are unparalleled in the valve industry. Our proportional valve line outperforms the competition in many ways.

The critical specifications engineers evaluate when selecting a high performance proportional flow control valve are linearity, frequency response and hysteresis. Other important features are repeatability, power consumption, leakage, life expectancy and cost.

Engineers at Teknocraft have advanced the state-of-the-art of proportional valves by designing units that meet the high performance end of all the above mentioned specifications while keeping the valve simple enough to hold costs down. Teknocraft has achieved an unparalleled linearity, an exceptionally high frequency response of 250 Hz. and low hysteresis using a unique solenoid construction.

True Proportionality

In the past, proportionality in valves was accomplished by using a linear solenoid or dithering an on/off solenoid. There are two types of linear solenoids. One uses a pulse-width modulated (PWM) electrical input signal to eliminate the effects of stiction. This reduces the frequency response of the valve. The second type of linear solenoid eliminates stiction by suspending the moving part (the armature) to eliminate metal-to-metal contact. While this has been the preferred choice, it involves a complex design and is expensive to manufacture. Dithering puts more burden on the complexity of the electronic circuitry and still does not yield the linearity needed in most closed-loop applications. For these reasons a truly proportional, more sophisticated, linear solenoid such as Teknocraft’s is preferred.

Linearity

In conventional proportional solenoids, reshaping the magnetic flux to achieve linearity involves the use of complex, tightly toleranced parts and difficult welding/brazing processes. For example, an axisymmetric tubular construction consisting of three parts made of different materials is achieved by a complicated fixturing/welding or brazing process. Within this tubular construction, the movement of the armature must be precisely controlled to ensure it never touches the sides of the armature housing as it travels in and out.

Engineers at Teknocraft have overcome these deficiencies by relocating the moving parts outside the core and situating the magnetic flux paths associated with linearizing the force-displacement characteristics outside the coil

Keeping the moving parts outside the core of the coil eliminates both the tightly toleranced parts and the rubbing of the armature within the armature housing. This also eliminates the need for welding or brazing

Proportional Valve Technical Article - Continued