Three-position valve position control circuit introduction

Three-position valve position control loop

The position control loop with a three-position valve is shown.

Figure a uses the circuit of the intermediate closed three-position valve. Due to the compressibility of the air, the positioning accuracy of the cylinder is poor. No leakage is allowed in this circuit and valve.

Figure b is a circuit using an intermediate pressurized three-position valve. When the valve is in the middle position, due to the double-out cylinder, the force balance is maintained on both sides of the piston, and the piston stays at any position of the stroke.

Figure c shows the circuit for controlling a single-rod cylinder. A pressure reducing valve is required to balance the forces on both sides of the piston. The intermediate pressure type three-position valve position control circuit is suitable for applications where the cylinder diameter is small and it is required to stop quickly in the middle of the stroke.

Figure d is a circuit using an intermediate pressure relief valve. The utility model is suitable for the occasion where the external force is free to push the piston to move, and in the case of safely operating the air in the cylinder chamber when the stop position is stopped, the disadvantage is that the inertia of the piston movement is large, and the stop position is difficult to control.

Three-position valve position control loop

Figure Position control loop with three-position valve

Among them: (a) intermediate closed type (b) intermediate pressure type (double output rod cylinder) (c) intermediate pressure type (single rod cylinder) (d) intermediate pressure relief type valve