JP2525034Y2 - Movable iron type proportional solenoid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Field of the Invention The present invention relates to a proportional solenoid. More specifically, the present invention is suitable for use in, for example, a proportional solenoid valve whose proportional characteristic is improved by providing a permanent magnet. The present invention relates to a movable iron type proportional solenoid.

(B) Prior Art A movable iron type proportional solenoid for a proportional solenoid valve in which a moving amount of a movable iron core is made to be proportional to an amount of current supplied to a coil has been widely known. The attraction force of such a solenoid is related to the exciting current depending on the BH characteristics of the magnetic material used. However, since the solenoid is used starting from a current value of zero for control, there is a problem in the low magnetizing force region that the current-attraction force characteristic has poor linearity as shown in the portion A in FIG.

In order to improve the linearity in such a low magnetizing force region, conventionally, (a) a method of processing a control signal and making an exciting current flowing through a coil proportional to an attractive force, or (b) a method of using a magnetic material is preferable. Although there has been a method of performing heat treatment using such a material, there is a problem that all of them are expensive.

(C) Problems to be solved by the present invention Problems to be solved by the present invention are as follows. By providing a permanent magnet in a movable iron type proportional solenoid for a proportional solenoid valve, a current-attraction force characteristic in a low magnetizing force region is provided. It is to improve the linearity.

(D) Means for Solving the Problems The present invention provides a fixed coil, a fixed iron core fitted in one end of the coil, and a movable iron core movably provided in a guide tube in the coil. A magnetic frame that surrounds the coil and limits a magnetic path from the fixed core to the movable core. An annular convex portion having a tapered tip is formed at an end of the fixed core on the movable core side. In order to improve the linearity of the current-attraction force characteristic in the low magnetizing force region where the exciting current of the coil is extremely small and the attraction force of the fixed iron core is insufficient, in the movable iron type proportional solenoid for the proportional solenoid valve provided above. A permanent magnet is provided between the magnetic frame and the movable core and outside the guide tube, and a core tube is provided inside the guide tube. The movable core is attracted by supplementing the attractive force and cooperating the attractive force of the fixed core and the attractive force of the permanent magnet.

(E) Operation In the above configuration, when the coil is not energized, the movable core is separated from the fixed core by a biasing force of a spring or the like. However, when the coil is energized, the movable core is fixed in proportion to the current value. It is drawn to the iron core side. In this case, since a permanent magnet is provided between the magnetic frame and the movable core and outside the guide tube, and a core tube is provided inside the guide tube, the magnetic gap between the permanent magnet and the movable core is extremely small. Due to the cooperation between the attractive force of the fixed core and the attractive force of the permanent magnet, the linearity of the current-attractive force characteristic is obtained even in the low magnetizing force region where the exciting current of the coil is extremely small and the attractive force of the fixed core is insufficient Is improved. The core tube also acts as a guide for moving the movable core.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a half of a cross section of a movable iron type proportional solenoid for a proportional solenoid valve according to the present embodiment.
In the figure, 1 is a solenoid, 2 is a coil, 3 is a fixed iron core fitted and fixed in one end (right end in the figure) of the coil, 4
Is a guide tube connected to the fixed core, 5 is a magnetic frame surrounding the coil, 6 is a movable core movably provided in the guide tube 4, 7 is a push fixed to the movable core and extending through the fixed core. It is a rod. At the end of the fixed iron core on the side of the movable iron core, a tip of a known shape is formed into a tapered shape by a conventional proportional solenoid, and an annular convex portion 8 is formed.

At the other end of the coil 2 (the left end in the figure), between the magnetic frame 5 and the guide tube 4, an annular permanent magnet 10 is provided.
Further, a core member 11 made of a magnetic material is fitted and fixed with the permanent magnet outside in the radial direction.

Since the permanent magnet 10 is provided outside the guide tube 4 due to dimensional restrictions for disposing the permanent magnet 10 in the proportional solenoid, the guide is provided so as to minimize the magnetic gap between the guide tube 4 and the movable core 6. A core tube 12 made of a magnetic material is fitted and fixed in the tube 4 at a position corresponding to the core member 11. The core tube 12 also acts as a guide for the movement of the movable core, and makes the linear movement of the movable core reliable and smooth. For this reason, it is desirable that the inner surface of the core tube 12 be subjected to a wear-resistant treatment.

Reference numeral 15 denotes a bearing sleeve for guiding the push rod movably, and 16 denotes a magnetic killer having a known structure.

In the movable iron type proportional solenoid having the above configuration, when the coil 2 is not energized, the movable iron core 6 is separated from the fixed iron core 3 by a pressing force of a spring or the like acting via the push rod 15.

Next, when the coil 2 is energized, a suction force is generated in the fixed iron core 3 to suck the movable iron core 6. At this time, the movement amount of the movable iron core 6 and the current value are substantially proportional to the relatively large current value due to the action of the annular convex portion 8 having a tapered tip like the conventional movable iron type proportional solenoid. . Thus, even when the current value is very small and close to zero, the attractive force-exciting current characteristic becomes closer to a straight line as compared with the case where no permanent magnet is provided, as shown by and in FIG. In particular, when the magnetic force of the permanent magnet is increased, it becomes closer to a straight line than when it is weak. Therefore, even if the current value is close to zero, the attraction force can be made substantially proportional to the exciting current.

(G) Effect According to the present invention, a permanent magnet is provided between the magnetic frame and the movable core and outside the guide tube, and a core tube is provided inside the guide tube so that the magnetic frame and the movable core With a permanent magnet in between, the structure of the conventional proportional solenoid valve is not greatly improved, and the structure is simple and inexpensive. Even in the low magnetizing force region, the exciting current of the solenoid and the attracting force can be approximately linearly proportional to the conventional characteristics, as shown in the attractive force vs. exciting current characteristic in FIG.

In addition, since the core tube is provided inside the guide tube, the core tube also acts as a guide for moving the movable core, so that the linear movement of the movable core can be made more reliable and smoother than before.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a half of an embodiment of a movable iron type proportional solenoid according to the present invention, FIG. 2 is a view showing a BH curve, and FIG. 3 is a diagram showing a relationship between an attractive force and an exciting current. FIG. 6 is a diagram showing a comparison between a movable iron core type proportional solenoid according to the present invention and a conventional movable iron core proportional solenoid. 1: Movable iron type proportional solenoid, 2: Coil 3: Fixed core, 5: Magnetic frame 6: Movable core, 10: Permanent magnet

Claims (1)

(57) [Scope of request for utility model registration] 1. A fixed coil, a fixed core fitted into one end of the coil, a movable core movably provided in a guide tube in the coil, and the fixed core surrounding the coil. A magnetic frame for limiting a magnetic path from the iron core to the movable iron core, wherein the fixed iron core has an end on the movable iron core side formed with an annular convex portion having a tapered tip. In the iron-type proportional solenoid, in order to improve the linearity of the current-attraction force characteristic in a low magnetizing force region where the exciting current of the coil is extremely small and the attraction force of the fixed core is insufficient, the magnetic frame and the movable iron core are used. And a permanent magnet is provided outside the guide tube, and a core tube is provided inside the guide tube. The attraction force of the permanent magnet replenishes the attraction force of the fixed core by the attraction force of the permanent magnet. A movable iron core type proportional solenoid for a proportional solenoid valve, wherein the movable iron core is attracted by cooperating with the attractive force of a permanent magnet.