JPH02133906A - Plunger type electromagnet - Google Patents

Abstract

PURPOSE:To keep a plunger safe even when a spring is deteriorated and to make a permanent magnet unnecessary by a method wherein an attraction wing sheet which is faced to an end face of a yoke and whose plane is larger than an outer diameter of the plunger is installed at an end part on the side opposite to a fixed iron core of the plunger and a length of the plunger is set to a prescribed length. CONSTITUTION:An attraction wing sheet 6 is brought into contact with an end face of a yoke 1; a very small gap t1 is formed between attraction faces of a plunger 3 and a fixed iron core 2. When an electric current at a coil 5 is ON, the attraction wing sheet 6 is attracted to the yoke 1; when the current becomes OFF, a remanent magnetic flux density between the attraction wing sheet 6 and the yoke 1 becomes smell, the attraction wing sheet 6 can be separated from the yoke 1 even by means of a spring which has been deteriorated with the passage of time. When an electromagnet is operated, attraction faces of the plunger 3 and the fixed iron core 2 are brought into contact; a very small gap t2 is formed between end faces of the attraction wing sheet 6 and the yoke 1; then, the plunger 3 and the fixed iron core 2 is kept in an attracted state by a strong remanent magnetic flux even when the electric current at the coil 5 becomes OFF; the plunger 3 cannot be separated from the fixed iron core 2 even by means of a normal spring; accordingly, a permanent magnet can be dispensed with.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a plunger type electromagnet, and more particularly to improving the operating characteristics of a plunger type electromagnet.

[Prior Art] A conventional plunger will be explained using a sectional view of an electromagnet. As shown in FIG. 4, the electromagnet separates a yoke l, a fixed iron core 2 fixed to the yoke l, a plunger 3 that abuts the fixed iron core 2, and a predetermined distance between the fixed iron core 2 and the plunger 3. A circuit composed of a spring (not shown), a guide pipe 4 that guides the operation of the plunger 3, a fixed iron core 2, a plunger 3, and a yoke 1 is magnetized by energization and resists the biasing force of the spring. It is composed of a coil 5 and the like that attract the plunger 3 to the fixed iron core 2.

Furthermore, FIG. 5 shows a conventional latching type electromagnet in which a permanent magnet 7 is attached to the side of the fixed iron core 2 so that the plunger 3 and the fixed iron core 2 remain attracted to each other even after the current in the coil 5 is turned off. ing.

[Problem to be solved by the invention 1 ■ The conventional plunger-type electromagnet shown in Fig. 4 is used in various fields because it is convenient to handle and inexpensive, but there are problems with processing accuracy during mass production or material quality. Due to changes in the coil's current and spring resistance, the plunger may not separate from the fixed core due to residual magnetic flux even when the coil current is turned off.For example, when used in a gas valve, gas may be released. There is a risk that In consideration of such accidents, the current situation is that strict controls are carried out in the selection of magnetic materials, annealing of the magnetic materials during the manufacturing process, processing tolerance control, etc.

Therefore, there has been a need for an electromagnet that can reliably separate the plunger from the fixed core when the coil current is turned off, thereby preventing accidents.

■Figure 5 shows an electromagnet used for locking, etc. Even when the current is turned off, the plunger is retained by the action of the permanent magnet and cannot be unlocked. Even if this permanent magnet is removed, an electromagnet that performs a similar latching operation is also desired in order to reduce manufacturing costs.

The present invention was proposed in order to solve the above-mentioned problems in operating characteristics when using a plunger type electromagnet, and to ensure that accidents in which the plunger becomes unable to return due to residual magnetic flux can be avoided. It is an object of the present invention to provide a plunger type electromagnet that is fail-safe or does not require a permanent magnet.

[Means for Solving the Problems] The present inventors have been promoting research and development on improving the performance of plunger type electromagnets, and have already made numerous proposals based on the results. The attraction force due to the residual magnetic flux between the fixed iron cores is controlled by using the attraction vanes developed by the present inventors.

The present invention solves the above-mentioned problems, and includes a yoke, a fixed iron core fixed to the yoke, a plunger whose end face is attached to and detached from the fixed iron core, and a spring that urges the end face of the fixed iron core in a direction away from the fixed iron core. It consists of a guide pipe that guides the plunger in the axial direction, a fixed core, a plunger, and a yoke.The circuit is made up of a fixed core, a plunger, and a yoke.It is made up of a coil that is energized to attract the plunger to the fixed core against the biasing force of the spring. It was applied to plunger-type electromagnets, and the following technical measures were taken. That is, a suction vane plate is provided at the end of the plunger opposite to the fixed iron core, facing the yoke end face perpendicular to the plunger axial direction, and having a facing plane larger than the outer diameter of the plunger. The length was set to a predetermined length.

■When the electromagnet is in operation, the suction vane and the end face of the yoke facing the suction vane come into contact, and the length of the plunger is such that there is a minute gap between the plunger and the suction surface of the fixed iron core. Or, ■When the electromagnet is activated, the plunger and the fixed iron core are in contact with each other, and if the length of the plunger is such that there is a minute gap between the suction vanes and the end face of the yoke facing the suction vanes, each It can exhibit distinctive effects.

[Effect 1 The attractive force F of the electromagnet as shown in Fig. 4 is expressed as follows: F = Φ2/S... (1) where the cross-sectional area of the plunger is s, Ia east is Φ, and K is a constant. Given. That is, the attraction force F is inversely proportional to S.

The present invention applies the relationship of equation (1) to the residual magnetic flux to control the attractive force due to the residual magnetic flux when the coil current is turned off.

A longitudinal sectional view of the plunger of the present invention is shown in FIG. The diameter of the plunger 3 is d, and the plunger 3 is provided with a suction vane 6 having a diameter of about 100 mm at its top.

As shown in Fig. 1, when the length of the plunger is configured such that when the electromagnet is activated, the suction blade 6 and the yoke 1 are in contact with each other, and there is a small gap between the suction surfaces of the plunger 3 and the fixed iron core 2. , the area ratio between the plunger 3 and the suction vane 6 is d''/(D-d), and if d/D=1/3, the suction force due to the residual m bundle is equal to This is reduced to 1/4 compared to the case shown in the figure. Therefore, when the current in the coil 5 is turned off, the plunger 3 can be reliably separated from the fixed iron core 2.

Furthermore, as shown in FIG. 2, if the length of the plunger is configured such that when the electromagnet is activated, the plunger 3 and the fixed iron core 2 are in contact with each other, and there is a small gap between the suction vane 6 and the yoke 1, When the current in the coil 5 is off, from the relationship in equation (1), since the abutting surface is small, the magnetic flux density of the residual magnetic flux is large and the attractive force is large, so the residual magnetic flux alone is sufficient to attract and hold the plunger 3. This makes it possible to eliminate the need for the permanent magnet 7 shown in FIG.

[Embodiment] An embodiment of the present invention is shown in FIGS. 1 and 2. In FIG. 1, an electromagnet changes the length of the plunger when activated by a suction vane plate 6 and a yoke l facing the suction vane plate 6. The end faces of the plunger 3 and the fixed iron core 2 were configured to be in contact with each other, and there was a small gap t1 between the attraction surfaces of the plunger 3 and the fixed iron core 2.

Therefore, when the current is on in the coil 5, the attraction blades 6 and the yoke 1 are attracted to each other as shown in FIG. 1, but when the current is turned off, the residual magnetic flux between the attraction blades 6 and the yoke 1 The density becomes smaller, so the suction force becomes smaller according to equation (1), and it becomes possible to separate the suction bow A handle 6 from the yoke 1 even with a spring (not shown) that has deteriorated over time.

Figure 2 shows that when the electromagnet is activated, the plunger length is set so that the attraction surfaces of the plunger 3 and fixed iron core 2 are in contact with each other, and the suction vane plate 6
There is a small gap L between the end faces of the yoke l facing the suction vane plate 6.
2.

In this case, as shown in Fig. 2, the plunger 3 and the fixed iron core 2 are in a suction state due to the action of a strong residual magnetic flux, not only when the current is on in the coil 5, but even when the current is off. maintained.

Therefore, not only a spring that has deteriorated over time, but also a normal spring (none of which is shown in the figure) will cause the plunger to 3.
It is impossible to separate it from the fixed iron core 2. Therefore, it is possible to omit the conventional permanent magnet.

Since the present invention is configured as described above, the biasing force when the spring is normal, the estimated biasing force when the spring deteriorates over time, and
By adjusting and combining the selection of the magnetic material of the plunger and the like, the diameter of the suction blades, and the minute gaps t1 and t2, it is possible to obtain a plunger type electromagnet that meets the needs.

〔Effect of the invention〕

The present invention makes it possible to control the attractive force between the plunger and the fixed core caused by the residual magnetic flux of the ferromagnetic material that constitutes the electric circuit, making it easy to select the materials for the core and yoke, and preventing the spring from deteriorating. Safety measures can be provided.

Furthermore, in plunger-type electromagnets that are desired to hold the plunger even when the current in the coil is turned off, it has become possible to eliminate the need for permanent magnets that were conventionally required.

[Brief explanation of the drawing]

Figures 1 to 3 are cross-sectional views of an embodiment of the present invention. Figure 1 shows the case where the suction vane plate and the yoke end face are in close contact, and Figure 2 shows the case where the plunger and the fixed iron core are in close contact with each other. , FIG. 3 is a plunger equipped with a suction vane, and FIGS. 4 and 5 are cross-sectional views of conventional examples. ■ Yoke 2 Fixed core 3 Plunger 4 Guide pipe 5 Coil 6 Attraction blade 7 Permanent magnet D Outer diameter of attraction vane d...-Plunger outer diameter t2, t2...Distance Applicant Mick Industries Co., Ltd. Agent

Claims (1)

[Scope of Claims] 1. A yoke, a fixed core fixed to the yoke, a plunger whose end face is attached to and detached from the fixed core, and a spring which biases the end face away from the fixed core. A circuit composed of a guide pipe that guides the plunger in the axial direction, the fixed core, the plunger, and the yoke is magnetized by energization, and the plunger is attracted to the fixed core against the biasing force of the spring. In a plunger-type electromagnet consisting of a coil, an opposite flat surface is provided at an end of the plunger opposite to the fixed iron core, facing the yoke end face perpendicular to the axial direction of the plunger and having a diameter larger than the outer diameter of the plunger. 1. A plunger type electromagnet, characterized in that a suction vane plate is provided, and the axial length of the plunger is set to a predetermined length. 2. When the electromagnet is in operation, the suction blade plate and the yoke end surface facing the suction blade plate are in contact with each other, and the length of the plunger is such that there is a minute gap between the plunger and the suction surface of the fixed iron core. Plunger type electromagnet as described. 3. When the electromagnet is activated, the plunger and the attraction surface of the fixed iron core are in contact with each other, and the length of the plunger is such that there is a minute gap between the suction vane plate and the end face of the yoke facing the suction vane plate. Plunger type electromagnet as described.