JPS5923371Y2 - dc solenoid - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a bistable self-holding DC solenoid that has a large stroke and suction thrust compared to its overall dimensions.

Several types of bistable self-holding DC solenoids have already been manufactured and used.

This is done by placing a permanent magnet in the middle of the yoke so that the same poles are facing each other, and attaching excitation coils on both sides of the permanent magnet.
A plunger is inserted into the excitation coil and permanent magnet so that it can move forward and backward.

The plunger is stable when it is attracted by two fixed iron cores fixed to the front and rear ends of the yoke.

It is called bistable because it is equally stable no matter which fixed core it is attracted to.

The magnetic flux passes from the permanent magnet, through the plunger, through the fixed iron core on the attraction side, and the yoke, and returns to the permanent magnet.

The transition between the two states is effected by applying a pulsed current to the excitation coil.

As such a bistable DC solenoid, Japanese Patent Application Laid-open No. 54
No.-42647, JP-A No. 52-10561, JP-A No. 52-10561
Ideas and inventions have been made such as No. 3-98953, Japanese Utility Model Application No. 53-98954, Japanese Utility Model Application No. 5294160, Japanese Utility Model Application Publication No. 52-50356, and Japanese Utility Model Application Publication No. 50-91050.

A bistable DC solenoid has fixed iron cores at the front and rear of the plunger, which are fixed to the yoke.

The plunger is attracted to the fixed iron core and becomes stable.

The fixed core has two roles: to reduce magnetic resistance and to function as a plunger stopper.

In the most common DC solenoid, which did not have a permanent magnet and was attracted and returned by the two actions of an excitation coil and a spring, the stroke of the plunger was not limited by the size of the solenoid.

For this reason, the fixed core behind the plunger can be made relatively long.

Also, if the contact surface between the fixed core and the plunger is flat,
The range of suction power was short.

This is because magnetic resistance is large.

Therefore, the contact surface between the individual core and the plunger is often made into an inclined surface that fits into the concave and convex portions.

It seems that many engineers are following the same idea when it comes to bistable self-retaining solenoids using permanent magnets, and they are devoting a considerable amount of space to the fixed iron core.

In addition to holding power, a DC solenoid also has stroke performance.

For solenoids with the same external dimensions, it can be said that a longer plunger stroke is better.

In the case of bistable solenoids, both ends of the plunger are closed with fixed iron cores.

The distance from the inner surface of one yoke to the inner surface of the opposing yoke is l, the stroke of the plunger is S, and the length of the enlarged diameter portion of the plunger is m.

Also, if the axial thickness of the fixed core is tl, tl, l=s+m+tx+tl.

The same is true for normal DC solenoids that do not use permanent magnets, but the shape of the contact surface between the fixed core and the plunger is carefully designed.

Some have a plunger and a fixed iron core that come into contact with each other on a flat surface.

Since the direction of the magnetic flux is perpendicular to the surface, the holding force during attraction is strong.

However, the dynamic suction force when transitioning from the separated state to the suction state is inferior.

Can only be used for short strokes. In some types, the plunger and the fixed core are in contact with each other through a conical surface.

Even when they are separated, there are some parts that are close to each other, so the magnetic resistance can be kept relatively low.

Wide range of suction power. The stroke can be longer than that of a flat surface.

However, when the two are in close contact with each other, the holding force is weak.

Because the surface is inclined, the magnetic force is not entirely effective against the axial attractive force.

To provide an inclined surface, the plunger may be a female type and the fixed core may be a male type.

Conversely, there are cases where the plunger is male and the fixed core is female.

If the length m of the expanded diameter portion of the plunger is small, looseness is likely to occur in the direction perpendicular to the axis.

When the plunger is tilted within the sleeve in a direction perpendicular to the axis, the frictional force increases.

This prevents smooth sliding movement.

The plunger and sliding tube are also significantly worn. This is because a clearance of 5/100 to 10/100 mm is required between the plunger and the sliding tube.

Therefore, in many cases, the plunger is made female and the fixed iron core is made male.

For example, Utility Model Application No. 53-98953, Utility Model Application No. 53i89
No. 54 and others reveal such male and female shapes.

In the case of a bistable type, the plunger moves in a narrow space sandwiched between two fixed iron cores, so this is necessary to ensure that the length m of the expanded diameter part of the plunger is sufficient so as not to impair the sliding characteristics. It seems that there are only such arrangements.

In the case of a monostable type, the plunger comes out from one hole, so a sufficient length m can be secured.

Therefore, it is more common for the rear part of the plunger to be male and the fixed iron core to be female.

However, in the case of bistable solenoids, the end faces of the plunger and fixed core are most often flat surfaces, for example, as disclosed in Japanese Utility Model Publication No. 52-50356 and Japanese Utility Model Application Publication No. 50-91.
No. 050, Utility Model Publication No. 52-94160, JP-A No. 53-1
No. 0561 and the like employ flat surfaces.

It is thought that these can only be used for short strokes.

FIG. 3 is a longitudinal sectional view showing an example of a conventional bistable self-holding DC solenoid.

The solenoid includes a yoke 1 with a rectangular cross section and permanent magnets 2, 2.
, excitation coils 3a, 3b, plunger 4', fixed cores 5', 6', etc.

The plunger 4', fixed cores 5' and 6', and yoke 1 are made of magnetic material, and the bushing rod 10' is made of non-magnetic material.

Due to the action of permanent magnets 2, 2... with the same poles facing each other,
The plunger 4' can be attracted to both the fixed iron core 5' at the rear and the fixed iron core 6' at the front, and can maintain that state.

The forward and backward positional displacement is achieved by passing an instantaneous current through the excitation coils 3a and 3b.

If you reverse the direction of the current, will it make a transition in the opposite direction?
can.

This uses a conventionally commonly used flat surface 21 on the front surface of the plunger and a conical surface 22 on the rear surface.

Here, the front refers to the direction F of the bush rod 10',
"Back" refers to the opposite direction R.

Focusing on the plunger, one in which the opposite corner relationship between the plunger and the fixed iron core is a flat surface 21 is called a flat type, and one in which the plunger is recessed (like the rear surface 24) is called a concave type.

A type in which the plunger protrudes and the fixed core is recessed is called a convex type.

In the example shown in Fig. 3, the front is flat and the rear is concave.

A convex type is not used because the expanded diameter portion of the plunger is long.

Since the front is flat, suction thrust tends to be insufficient during forward transition F.

Therefore, it is necessary to add a coil spong 23 to the bush rod 10' to supplement the suction thrust.

Since the rear is concave, the suction thrust toward the rear is greater.

However, this cannot be increased much.

This is because if the conical recess 24 is made deeper, the embedded portion 25 of the bushing rod 10' becomes too thin and weak.

If a flat or concave plunger is used, the axial thicknesses tl and t2 of the fixed core can be made thinner, and the length m of the expanded diameter portion of the plunger can be made longer.

It appears that convex-shaped plungers have never been used in bistable self-retaining solenoids.

This is probably because there is a common belief that increasing the thicknesses tl and t2 of the fixed core and decreasing the length m of the enlarged diameter portion of the plunger deteriorates the sliding characteristics of the plunger.

However, the present inventor realized that a convex plunger is better than a concave plunger in increasing suction thrust.

In fact, convex plungers are often used in monostable self-holding solenoids and frequently used solenoids without magnets.

This is because there is no restriction on the length of the plunger enlarged diameter portion m.

The inventor of the present invention wondered what could be done to ensure a sufficient length of the enlarged diameter part m of the plunger, even though it is a convex plunger.
I pondered the issue.

Then, I got the following idea.

The convex part at the end of the plunger does not need to be inside the yoke.
It's okay to just take it outside.

In other words, diameter-reducing convex portions are formed at both ends of the plunger, but the end surfaces of the convex portions are made to protrude outward from the inner surface of the yoke during suction.

Then, a convex plunger can be made without reducing either the stroke S or the length m of the plunger enlarged diameter portion.

This is the main point of this idea.

Hereinafter, the structure, operation, and effects of the present invention will be explained with reference to drawings showing embodiments.

FIG. 1 is a longitudinal sectional view of a DC solenoid according to an embodiment of the present invention.

This solenoid consists of a yoke 1, permanent magnets 2, 2, 2, exciting coils 3a, 3b, plunger 4, and fixed iron core 5.
, 6 etc.

The yoke 1 is made of a magnetic material with a rectangular cross section.

In this example, a U-shaped cross section plate 14 and a flat plate 15 are combined,
It forms a closed magnetic path.

The permanent magnets 2, 2, . . . are fixed at substantially intermediate positions within the yoke 1 so that the same poles face inward.

Two to four permanent magnets are used, but three are often used.

Excitation coils 3 a and 3 b are provided before and after permanent magnets 2 and 2.

It is momentarily energized to move the plunger.

By switching the direction of the current, the plunger can be moved back and forth.

Currents in the same direction are simultaneously applied to the two exciting coils 3a3b.

Plunger 4 is made of magnetic material.

A front reduced diameter convex portion 8 and a rear reduced diameter convex portion 9 are formed before and after the enlarged diameter portion 7.

In other words, it is a convex plunger according to the above definition.

The fixed cores 5 and 6 are thin ring-shaped with a hole in the center.
It can be attached to the front and rear of yoke 1 by caulking.

The important thing is that the plunger has diameter-reducing convex portions 8 and 9, and when the outer end surface S of the convex portions 8 and 9 is sucked in the direction of the convex portions,
This means that it is located outside the inner surface T of the yoke 1.

That is, the heights H1 and H2 of the diameter-reducing convex portion are the axial thickness t of the fixed core, 1. Hl)tx H2>t2.

In this case, since the length of the plunger becomes longer, the length m of the enlarged diameter portion 7 can be increased even if it is a convex type.

This means that the plunger does not rattle.

Moreover, since it is convex, a large suction thrust can be obtained.

The front diameter-reducing convex portion 8 of the plunger 4 has a female thread, and a non-magnetic bushing rod 10 is fixed to the tip thereof.

A yoke 12 is interposed between the permanent magnets 2, 2, . . . and the sleeve 13 to prevent leakage of magnetic flux.

In this example, the rear diameter-reducing convex portion 9 penetrates through the fixed iron core 5 and protrudes from the rear end.

FIG. 2 is a longitudinal sectional view showing another embodiment.

This shows the state of being sucked forward.

In this example, the front diameter-reducing convex portion 8 is separated.

The male threaded end of a non-magnetic bushing rod 10 is screwed into this.

Other points are the same as the first embodiment.

Describe the action.

In Figure 1, plunger 4, fixed core 5, yoke 1,
There is a magnetic flux passing through the permanent magnet 2.

Due to the energy of this magnetic flux, the plunger 4 and the fixed iron core 5 are brought into close contact and stable.

When a counterclockwise current is instantaneously passed through the excitation coils 3a and 3b, the magnetic flux of the coil 3b cancels the magnetic flux of the permanent magnet 2.

The magnetic flux of the coil 3a draws the plunger 4 forward.

Therefore, the plunger moves forward and comes into close contact with the front fixed core.

This state is also stable. When a current in the opposite direction is passed through the excitation coil, the magnetic flux from the coil 3a cancels the magnetic flux from the permanent magnet 2.

The magnetic flux from the coil 3b pulls the plunger 4 back.

The edges 11 of the diameter-reducing convex portions 8, 9 and the edges 16, 16 of the fixed cores 5, 6 are extremely close to each other even when they are separated.

Therefore, the attraction thrust generated when the excitation coil is energized is large.

This is because the magnetic flux Φ is concentrated so as to connect the edges 11 and 16, surface magnetic charges are generated on the edges, and they attract each other.

It may be because the magnetic resistance is low. Furthermore, it can also be expressed that the magnetic flux density becomes high between the edges, and the Maxwell stress (magnetic flux density x magnetic field) is large.

Despite having a convex shape and having a large suction thrust, the length m of the enlarged diameter portion 7 is not shortened.

This is because the diameter-reducing convex portions 8 and 9 are configured to protrude outward from the inner end surface T of the yoke, without the usual restriction that they are located within the yoke 1.

This invention is the first to use a convex plunger with a large suction thrust in a bistable self-holding DC solenoid.

Moreover, since the end surface S of the diameter-reducing convex portion of the plunger is made to protrude outside from the inner surface T of the yoke during suction, the thickness of the fixed core is 1. ．． 1. , can be suppressed.

The length m of the expanded diameter part of the plunger can be increased, and the sliding characteristics are stable.

Let's actually compare the suction thrust of the conventional example shown in Fig. 1 and that shown in Fig. 3.

FIG. 4 shows the front thrust F1 and rear thrust R1 of the DC solenoid according to the embodiment of the present invention, and the front thrust F2 and rear thrust R2 of the conventional solenoid in FIG. 3, with respect to the pulse voltage of the exciting coil. , is an experimental graph showing how it changes.

The magnet, the number of turns of the excitation coil, the DC resistance, the dimensions of the yoke, etc. are all the same.

In other words, the stroke is 5.5m, the magnetic flux density on the end face of the permanent magnet is 7000 Gauss, the large diameter part of the plunger is 9MQx18m, and the number of turns is 25.
DC resistance of 0 x 2 winding is 11Ω Yoke dimensions are 25 pieces x 25 pieces x 31 4 pieces magnet size (all 3 pieces) 4.5w x 5at x 11.5w
The front thrust F2 of the conventional solenoid is the smallest.

This is due to the fact that the front surface of the plunger in FIG. 3 is a flat surface 21.

At an applied voltage of 29V, the maximum suction thrust is only 276g.

The rear thrust R2 of the conventional solenoid is slightly improved due to the inclined surface 22.

The maximum suction thrust was 360 g at an applied voltage of 27 V.

Here, the attraction thrust is defined as the maximum load force (Durham force) that allows the plunger to move when a load is applied and an excitation voltage is applied to the excitation coil.

In this example, the maximum pre-suction thrust F1 is shown at 27■,
At this time, the weight reached 455g.

This is approximately 1.6 times that of the conventional example.

Further, the rear thrust R1 reached its maximum at 30V and reached 540g.

This is approximately 1.5 times that of the conventional example. In this way, the plunger of the present invention has a greater suction thrust than the conventional plunger both at the front and the rear.

The holding power during suction is Solenoid of this invention (Fig. 1) Rear holding force 4.3 hours Forward holding force 4.3 Solenoid of conventional example (Fig. 3) Rear holding force 2.8 instant Forward holding force increased to 4°3! 9 It is.

The rear holding force refers to the holding force that acts between the rear fixed iron core 5 and the rear end face of the plunger.

Measure and find the minimum traction force required to pull it forward.

The backward holding force of the conventional solenoid is weak because of the inclined surface 22.
This corresponds to the fact that the axial component of the magnetic flux becomes weaker.

The diameter-reducing convex portions 8 and 9 of the solenoid in Fig. 1 are both 4.5
mmφ, but the front convex part 8 is threaded, so
The magnetic resistance increases, and as shown in Figure 4, the forward thrust F1
is smaller than the rear thrust R1 by g.

In this example, the diameter-reducing convex portions 8 and 9 are simply cylindrical, but
Of course, it may also be shaped like a truncated cone.

If there is sufficient strength at the rear and front of the yoke, the fixed cores 5 and 6
can also be omitted.

As explained in detail above, the present invention provides diameter-reducing convex portions at both ends of the plunger to increase the suction thrust.
Since the length m of the enlarged diameter portion of the plunger can also be increased, there is little wobbling in the direction perpendicular to the axis.

After all, the stroke of the plunger can be lengthened or the suction thrust can be increased for the same current, so power consumption can be reduced.

This is a useful idea.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a DC solenoid according to an embodiment of the present invention, FIG. 2 is a vertical cross-sectional view of a DC solenoid according to another embodiment, FIG. 3 is a vertical cross-sectional view of a conventional solenoid, and FIG. The horizontal axis represents the applied voltage, and the longitudinal suction thrust F, R, of the solenoid of the present invention and the longitudinal suction thrust F2. of the conventional example. A graph showing experimental results with R2. 1...Yoke, 2...Permanent magnet, 3.
...Exciting coil, 4...Plunger, 5
, 6... Fixed iron core, 7... Expanded diameter part of plunger, 8, 9... Diameter reduced convex part, 10...
...Bush rod, 11...Edge of convex part,
12...Yoke, 13...Sleeve, 1
6... Edge of fixed iron core, l... Distance between yoke inner surfaces, m... Length of plunger expanded diameter section,
tl. t2... Thickness of fixed core, Hl, R2...
・・Height of diameter reduction convex part, S・・・Stroke, F・・
...Forward thrust, R...Rear thrust, S...
・Outer end surface of the diameter-reducing convex portion, T...Inner end surface of the yoke.

Claims (1)

[Scope of utility model registration request] A yoke 1 made of a magnetic material with a rectangular cross section; a short cylindrical fixed core 5 fitted into the center of the front end plate and rear end plate of the yoke 1, respectively;
, 6; Permanent magnets 2, 2... provided at approximately midpoints in the yoke 1 so that the same poles face each other, and permanent magnets 2, 2...... provided in the yoke 1 on both sides Excitation coil 3 installed in
a, 3b, and a plunger 4 made of a magnetic material and provided so as to be freely retractable into the excitation coils 3a, 3b and the permanent magnets 2, 2. Diameter-reducing protrusions 8 and 9 are formed at the front and rear of the plunger 4, respectively, and when the plunger 4 is attracted, the stepped end surfaces of the diameter-reducing protrusions inserted into the fixed core are brought into contact with the planes of the inner end surfaces of the fixed core, respectively. A bistable self-holding type DC solenoid characterized in that the end surface S of the diameter-reducing convex portion on the sucked side is located outward from the inner surface T of the yoke 1.