What is the difference between the three-position four-way electromagnetic reversing valve and the two-position four-way electromagnetic reversing valve in the structure and working mode of injection

What is the difference between the three-position four-way electromagnetic reversing valve and the two-position four-way electromagnetic reversing valve in the structure and working mode of injection molding machine? ... What is the difference between the three-position four-way electromagnetic reversing valve and the two-position four-way electromagnetic reversing valve in the structure and working mode of injection molding machine? Compared with the two-position four-way electromagnetic directional valve, the spool of the three-position four-way electromagnetic directional valve has three stop positions; There are two electromagnets, one at the left and right ends of the valve body. Its specific structure is shown in the following figure. The working mode of the three-position four-way electromagnetic directional valve is as follows: when the right electromagnet is energized and the left electromagnet is de-energized, the valve core is pushed to the left by the right spring; When the left electromagnet is energized, the left spring pushes the intelligent magnetic core to the right. The two different stop positions of the wide core are the same as those of the two-position four-way electromagnetic directional control valve, except that the directions of hydraulic oil and oil return have changed: when the right electromagnet is energized, hydraulic oil enters A from P, and oil return enters O from B; When the left electromagnet is energized, the hydraulic oil enters from P, discharges from B, and the return oil enters from A and discharges from O. If the left and right electromagnets are completely disconnected, the spool stops at the middle position in the valve body under the action of the left and right spring forces, and the four oil inlets and oil outlets are sealed by the spool, and the input and output of hydraulic oil stop. Three-position four-way electromagnetic reversing valve structure ①-electromagnet; ②—Push rod; ③-spring; 1- spool; 2— Valve body; O, b- hydraulic oil outlet; A, p- hydraulic oil inlet