JPH0349203A - Plunger type electromagnet - Google Patents

Abstract

PURPOSE:To alleviate the shock of hit by a movable plunger against a stator yoke and to secure a constant gap between them when energized by holding an elastic member between these yokes. CONSTITUTION:A coil 1 which is hold by a holder 3 forming a magnetic circuit is wound on a cylindrical bobbin 2. To the rear part of a circular hole 2a of said cylindrical bobbin 2, the holder 3 is engaged and fixed. Through a small hole of said holder 3, a stator yoke 4 is fixed. In a conical projection part 4c of said stator yoke 4, a ring-form elastic member 5 made of silicone rubber and etc., is set. When this coil 1 is energized electrically, a plunger yoke 6 set in front of the circular hole 2a is moved and the member 5 is pinched and held by the yokes 4 and 6. Thus, the hit shock of both yokes can be alleviated and a noise is not produced. Also, an interval between the stator yoke and the plunger yoke is made constant by the elastic member without changing a shape, size, and etc., so that its quick operation can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a plunger type electromagnet that reciprocates a movable yoke within a bobbin by controlling energization to a coil.

(Prior Art) Conventional plunger-type electromagnets of this type include those shown in FIGS. 4 and 5, for example.

The plunger type electromagnet shown in FIG. 4 has a coil 34 wound around the outer periphery of a cylindrical bobbin 33, and the front and rear ends of the bobbin 33 are fixed to both ends of a holder 36 that constitutes a magnetic circuit. There is. Inside the inner hole 35 of the bobbin 33, a fixed yoke 32 made of magnetic metal is installed at the rear of the holder 3.
6, and a movable yoke 31 made of magnetic metal is inserted into the front part thereof so as to be movable in the axial direction, with the distal end protruding beyond the inner hole 35. The movable yoke 31 is, for example, a lever (not shown) biased by a spring.
The tip part engages with the fixed yoke 32 and - due to the spring force.
When a constant gap is maintained and the coil 34 is energized, the movable yoke 31 moves against the spring force and is attracted to the fixed yoke 32. Then, when the energization to the coil 34 is stopped,
The above spring force returns it to its original position.

However, in such a plunger type electromagnet, the movable yoke 31 is connected to the fixed yoke 3 by energizing the coil 34.
Since both yokes 31 and 32 are made of magnetic metal, when the two yokes collide with each other, a large amount of noise is generated, and the metallic sound is particularly harsh. In addition, when used repeatedly, the impact of collisions could cause metal powder to flake off, causing malfunctions.

Further, since the yokes 31 and 32 are separated from each other when the coil 34 is stopped from being in close contact with each other, it takes a long time from when the energization is stopped until the yokes are separated, and the variation is large.

FIG. 5 shows a conventional plunger type II magnet that solves the above-mentioned drawbacks, in which a flange portion 31a is formed on the movable yoke 31 facing the front end of the holder 36, and an elastic member 37 such as rubber is attached to the front end of the holder 36. The flange portion 31a is attached to the movable yoke 31 so that it can come into contact with the elastic member 37, and the elastic member 37 is used as a buffer stopper.
When the movable yoke 31 and the fixed yoke 32 move toward the fixed yoke 32, the elastic member 37 acts as a buffer material, and the collision between the movable yoke 31 and the fixed yoke 32 is alleviated.

[Problem XI that the invention seeks to solve]

By the way, in the conventional plunger type electromagnet shown in FIG.
6 and the flange portion 31a of the movable yoke 31 to form a certain gap between the movable yoke 31 and the fixed yoke 32. The gap between the movable yoke and the fixed yoke varies when the movable yoke 31 is attracted due to the dimensional tolerances of each component such as the bobbin and holder that make up the holder, and the gap on the magnetic circuit of the electromagnet changes, causing the attraction force to change, The holding force became unstable, and the cutting characteristics when the current to the coil was stopped also changed and became unstable. Here, the breakage characteristic refers to the time it takes for the yoke to actually separate after the energization is stopped, and the variation in that time.

The purpose of the present invention is to alleviate the impact caused by the collision between the movable yoke and the fixed yoke, reduce noise, and improve durability, as well as to maintain a constant gap between the fixed yoke and the movable yoke regardless of the dimensional tolerance of each part. An object of the present invention is to provide a plunger type electromagnet that can stabilize cutting characteristics, adsorption force, and holding force.

(Means for Solving the Problems) The gist of the present invention is to provide a yoke fixed within a bobbin around which a coil is wound.
A movable yoke that is movable relative to the fixed yoke is provided,
By energizing the coil, the movable yoke is attracted towards the fixed yoke! A plunger-type electromagnet configured to work three times, characterized in that at least one of the yokes is provided with an elastic member that is held between both yokes when the movable coil is attracted. be.

(Function) In the plunger type electromagnet having the above configuration, when the movable yokes are attracted, an elastic member is held between both yokes, and a certain gap is formed between both yokes.

[Example] Example 1 FIG. 1 is a perspective view of an electromagnet showing Example 1 of the present invention. 2 is a cylindrical bobbin having a cylindrical hole 2a;
A coil 1 whose energization is controlled by an electric circuit (not shown) is wound around the outer periphery. Reference numeral 3 denotes a U-shaped holder constituting a magnetic circuit, in which the bobbin 2 is held and fixed between a rear end bent piece 3a and a front end bent piece 3b. A fixed yoke 4 is fitted into the rear part of the circular hole 2a of the bobbin 2, and the rear end protrusion 4b is fitted and fixed into the small hole 3C of the rear end bent piece part 3a of the holder 3. A movable yoke 6 is inserted into the front part of the circular hole 2a of the bobbin 2, and is inserted so that the front end where the small diameter part 6a is formed projects forward from the front end surface of the bobbin 2. When the coil 1 is energized, It moves toward the fixed yoke 4.

A conical protrusion 4c is formed at the front end of the fixed yoke 4, and a circumferential groove 48 is formed at the base of the conical protrusion 4C. Further, a conical hole 6b is formed at the rear end of the movable yoke 6, and faces the conical protrusion 4C of the fixed yoke 4 with a constant gap when the movable yoke 6 is energized and attracted.

Reference numeral 5 denotes an annular elastic member made of silicone rubber or the like, which is fitted into the circumferential groove 4a of the fixed yoke 4, and collides with the rear end surface of the movable yoke 6 when the movable yoke 6 is sucked.

FIG. 2 is a plan view of the above-mentioned plunger type electromagnet used as a drive source in a camera's lens extension mechanism and shutter opening/closing mechanism, and FIG. 3 is a sectional view of FIG. 2 with a lens barrel added.

A is a plunger type electromagnet used as a driving source for the lens extending mechanism, and B is a plunger type electromagnet used as a driving source for the shutter opening/closing mechanism. Reference numeral 7 denotes a rotary lever, which rotates around a shaft 7a embedded in the base plate 28, and a dowel 7b provided on the rotary lever fits into the small diameter portion 6a of the movable yoke 6 of the electromagnet A, and the movable yoke The linear reciprocating motion of 6 is converted into a rotational reciprocating motion. Reference numeral 8 denotes a drive lever in which an eccentric pin 8a is engaged with the rotary lever 7, and rotates around the shaft 7a together with the rotary lever 7. Reference numeral 9 denotes a feed pawl, which is rotatable around a shaft 9a on the drive lever 8, and a pawl at the tip thereof can engage with a pawl on a cam ring 11, which will be described later. A spring 10 biases the feed claw 9 clockwise and at the same time biases the rotary lever 7 and drive lever 8 counterclockwise, thus biasing the movable yoke 6 in the direction away from the fixed yoke 4. are doing. The rotary lever 7 has a stopper (not shown), and when the coil 1 is not energized, it remains in the state shown in FIG. 2. 12 is a locking pawl, and the pawl at the tip is the cam ring 11.
It is biased clockwise by a spring 13, and allows the cam ring 11 to rotate clockwise, but locks and stops the cam ring 11 from rotating counterclockwise. 11 is the cam ring,
Claws are formed on the outer periphery over the entire circumference, and a cam surface 11a whose cam height in the axial direction changes with rotation is formed on the upper surface. Reference numeral 14 denotes a lens barrel that holds the photographic lens L, to which a guide bar 16 extending in the optical axis direction is fixed, and a third
It is biased downward in the figure. A screw 15 is screwed into the lens barrel 14 along the optical axis direction, the lower end of which is in pressure contact with the cam surface 11a of the cam ring 11, and the lens barrel 14 is extended in conjunction with the rotation of the cam ring 11. .

On the other hand, 18 is the closing lever of the shutter opening/closing mechanism, and the shaft 1
8a, and a dowel 18b provided at one end fits into the small diameter portion 6a of the movable yoke 6 of the electromagnet B.
It rotates in conjunction with the reciprocation of the movable yoke 6. A spring 19 biases the closing lever 18 counterclockwise, and thus biases the movable yoke 6 of the electromagnet B in a direction away from the fixed yoke 4. 20 is open/'C-, has a blade drive pin 20b, is rotatable around a shaft 20a, and is biased clockwise by a spring 21 (with a weaker spring force than spring 19), which drives the dowel 20c. It can come into contact with the closing lever 18 through the opening. 22 and 23 are shutter blades that open and close in conjunction with the rotation of the opening lever 20 via the blade drive pin 20b.

In the lens feeding mechanism described above, when the coil 1 of the electromagnet A is repeatedly energized/stopped, the movable yoke 6 moves to the elastic member 5.
Repeat the suction/11 reversals with the fixed yoke 4 while holding the yoke. The reciprocating motion of the movable yoke 6 is transformed into a reciprocating rotational motion of the rotary lever 7 and the drive lever 8, and is further transmitted as a left-right swinging motion of the feed pawl 9. When the feed claw 9 moves to the right and reaches A,
The cam ring 11 is moved clockwise by the contact between the pawl of the feed pawl 9 and the pawl of the cam ring, and when the cam ring 11 advances by one tooth or more at the locking pawl 12, the energization to the coil l is stopped and the feed pawl 9 moves to the left. However, the cam ring 11 is stopped by the locking pawl 12 and stops at a position advanced by one tooth, and the lens is extended via the cam surface in accordance with the rotation angle of one tooth. and,
By repeating energization/de-energization of the coil 1, the lens barrel 14 is sequentially extended. Note that the cam surface of the cam ring 11 is provided with a step, and returns to its original height after one rotation.

Next, the shutter opening/closing mechanism described above is based on the coil 1 of electromagnet B.
When energized, the movable yoke 6 is attracted and comes into close contact with the fixed yoke 4, sandwiching the elastic member 5. Movable yoke 6
The closing lever 18 is rotated clockwise in conjunction with the closing lever 18, and the opening lever 20 is rotated clockwise by the spring 21 behind the closing lever 18, and the shutter blades 22 and 23 are opened. When the coil 1 is de-energized, the closing lever 18 is rotated counterclockwise by the spring 19, pushing the dowel 20c on the way and returning the opening lever 20 counterclockwise to close the shutter blade.

As explained above, the plunger-type electromagnet according to the present embodiment has a structure in which when the coil 1 is energized and the movable yoke 6 is attracted, the elastic member 5 is sandwiched between the fixed yoke 4 and the metals. This prevents collisions and reduces impact, reducing noise, especially harsh metallic sounds. Furthermore, there are no problems such as peeling off of metal powder, and durability is improved. Furthermore, since the only component interposed between the fixed yoke 4 and the movable yoke 6 is the elastic member 5, the dimensional tolerance of the gap in the magnetic circuit is limited to the accuracy of the thickness of the elastic member 5, unlike the conventional example shown in FIG. As a result, the gap size is stable, and therefore the adsorption force and holding force are stable. Also, a conventional example where metals are in close contact with each other (Fig. 4)
In this case, a strong attraction force is obtained when the coil is energized, but when the energization is stopped, it takes a long time for the movable yoke to separate, and the time varies. According to this embodiment, although the magnitude of the adsorption force during suction is slightly reduced, the time required for separation is short and stable.

Note that when the elastic member 5, which is formed in an annular shape, is attached to the circumferential groove 48 provided in the fixed yoke 4, the inner diameter is temporarily expanded and the elastic member 5 is fitted into the circumferential groove 48 provided in the fixed yoke 4. Since it is installed in the position shown in FIG. 1 and does not fall off, it is easy to assemble, and there are no problems such as adhesive sticking out, improving reliability.

Example 2 FIG. 6 shows a sectional view of the second embodiment.

In the first embodiment described above, the conical protrusion 4C is provided at the front end of the fixed yoke 4, and the conical hole 6b facing the conical protrusion 4C is formed at the rear end of the movable yoke 6. , conversely, a conical protrusion 56b is formed at the lower end of the movable yoke 56, a circumferential groove 56a is formed at its base, the elastic member 5 is fitted into the circumferential groove 56a, and the front end of the fixed yoke 54 A conical hole 54a is formed in which a conical protrusion 58b faces.

In this embodiment, since the elastic member 5 is provided on the movable yoke 56, the elastic member 5 is adjusted so that the sliding between the inner surface of the circular hole of the bobbin 2 and the elastic member 5 does not affect the operation of the movable yoke 56. It is necessary to consider the outer diameter dimensions, etc.

Example 3 FIG. 7 shows a cross-sectional view of the third embodiment.

In this embodiment, the movable yoke 66 is similar to the second embodiment described above.
A conical protrusion 86b is formed at the lower end of the fixed yoke 6.
In this embodiment, a conical hole a4a is formed at the front end of the fixed yoke 64, and in this embodiment, a hole 64b is coaxially formed in the fixed yoke 64 in series with the conical hole 64a. Member 65 is attached. This elastic member 65 is formed to be longer than the depth of the hole 64b, and is compressed and deformed by contacting the conical protrusion 66b of the movable yoke 66 when the movable yoke 66 is attracted, and is fixed between the movable yoke 66 and the fixed yoke 64. A slight gap is formed. Further, the elastic member 65 has an outer diameter slightly larger than the inner diameter of the hole 84b, and is press-fitted into the hole 84b or fixed to the hole 64b by adhesive or the like.

In each of the above embodiments, the elastic member is provided on one yoke, but it may be provided on both yokes.

(Effects of the Invention) As described above, according to the present invention, the collision between both yokes when the coil is energized is alleviated by the elastic member, and an electromagnet with low noise and excellent durability can be obtained.

In addition, since the elastic member is sandwiched between both yokes when the coil is energized, the gap between both yokes can be maintained constant, the adsorption force and holding force are stable, and the time required for separation is shortened.
An electromagnet with stable cutting characteristics that can reduce the variation in time can be obtained.

In general, the elastic member can be attached with a simple structure, for example, by forming a constriction at the distal end of a fixed yoke and fitting the elastic member into the constriction.

[Brief explanation of drawings]

FIG. 1 shows a first embodiment of a plunger type electromagnet according to the present invention.
FIG. 2 is a plan view of the electromagnet of Example 1 used as a drive source for the camera's lens feeding mechanism and shutter opening/closing mechanism, and FIG. 3 is a sectional view of FIG. 2 with the lens barrel added. , 4 and 5 are sectional views of conventional plunger type electromagnets, FIG. 6 is a sectional view of a second embodiment, and FIG. 7 is a sectional view of a third embodiment. 1...Coil 2...Bobbin 3...Holder 4.54.64...Fixed yoke 5.65...Elastic member 6.56.66...Movable yoke 4 people Figure 1 Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] 1. A fixed yoke and a movable yoke that are movable relative to the fixed yoke are provided in a bobbin around which a coil is wound around the outer periphery, and when the coil is energized, the movable yoke is The plunger-type electromagnet is characterized in that at least one of the yokes is provided with an elastic member that is held between both yokes when the movable coil is attracted. Plunger type electromagnet. 2. The plunger type electromagnet according to claim 1, wherein a constriction is formed at the tip of the fixed yoke, and the elastic member is fitted into the constriction.