JPH0969432A - Electromagnetic solenoid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the title electromagnetic solenoid subject to the least fluctuation in the characteristics of magnetic attraction extending over them whole stroke region wherein a needle is shifting. SOLUTION: The title recession type electromagnetic solenoid 1 is provided with an electromagnetic coil 2, a yoke 3 and a fixed iron core 4 magnetization- controlled by an exciting current running in the electromagnetic coil 2, a needle 5 arranged to be shifted on the same axis of the fixed iron core 4 magnetically conducted thereby 4 as well as a spring 7 opposing to the magnetic attraction between the fixed iron core 4 and the needle 5. At this time, respective opposing parts of the fixed iron core 4 and the needle 5 correspond to each other in truncated cone shape in the needle 5 while the fixed iron core 4 almost correspond to the same. In such a constitution, the distance between respective opposing parts in the orthogonal direction to the axial direction is made the longer toward the front end side of the needle 5 when the needle 5 is closest to the fixed iron core 4.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an electromagnetic solenoid.

[0002]

2. Description of the Related Art A valve opening is operated electrically.
For example, an electromagnetic solenoid used as a drive source for controlling the opening of a valve of an exhaust gas recirculation device of a diesel engine is required to have a magnetic attractive force characteristic proportional to an exciting current flowing in an electromagnetic coil in order to simplify its control circuit. It In general, an electromagnetic solenoid is combined with a spring and operated proportionally by an exciting current to control the valve opening. Electromagnetic solenoids for such applications are designed to reduce the fluctuation of the magnetic attractive force over the entire stroke range of the mover by placing the facing parts of the fixed iron core and the mover on the mover side. The fixed iron core has a concave shape substantially corresponding to the truncated cone shape. Regarding the magnetic attraction characteristics of the fixed iron core and the mover in the axial direction, in order to increase the magnetic attraction in a certain specific range in the axial direction, one of the conical trapezoidal shapes of the facing portion of the fixed iron and the mover is used. It is disclosed that the taper angle is a substantially conical taper that changes in accordance with the axial position. (For example, JP-A-58
-86709)

[0003]

In the above-mentioned one, the fluctuation of the magnetic attractive force is small in comparison with the one in which the facing portions are made flat with each other. However, when it is finely divided, the magnetic attraction force to the mover becomes large in the range where the stroke starts, that is, when the exciting current starts to flow, compared to the other ranges. Therefore, when a proportional operation of the valve opening by the exciting current is performed in the entire stroke, an error occurs at the beginning of the stroke. If the error cannot be ignored, the stroke range of the electromagnetic solenoid used to operate the valve opening should be reduced, or the position of the mover should be detected electrically and the detected value should be adjusted to the correct value. In addition, an arithmetic circuit for adjusting the exciting current is required, which is a major obstacle to cost reduction.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electromagnetic solenoid having a small variation in magnetic attractive force characteristics over the entire stroke of movement of a mover. .

[0005]

In order to achieve the above object, an electromagnetic solenoid according to claim 1 is provided with an electromagnetic coil,
A yoke and a fixed iron core whose magnetization is controlled by an exciting current flowing through the electromagnetic coil, a mover arranged so as to move on the same axis by receiving a magnetic attractive force from the fixed iron core, and the fixed iron core and the mover. Each of the facing portions of the fixed iron core and the mover, which includes a spring that opposes the magnetic attraction between the
In the electromagnetic solenoid in which the mover has a truncated cone shape and the fixed iron core has a concave shape substantially corresponding thereto, the distance between the facing portions in the axial direction and the orthogonal direction is such that the mover is closest to the fixed iron core. At this time, the movable element is formed so that it becomes larger toward the tip side. As a result, it is possible to reduce the change in the magnetic attractive force over the entire stroke of displacement of the mover.

The electromagnetic solenoid according to claim 2 is
Each of the facing portions is formed at a position where the starting points of the moving elements are substantially coincident with each other in the axial direction when the mover is closest to the fixed iron core. As a result, a high magnetic attractive force that is small in change throughout the displacement stroke of the mover can be obtained.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. This electromagnetic solenoid 1
The electromagnetic coil 2, the yoke 3, the fixed iron core 4, the mover 5 having the shaft 6, the bearings 8 and 9 for supporting the shaft, the position sensor 10 for detecting the position of the shaft, and the spring 7.
And the casing 11 as main constituent members.

The electromagnetic coil 2 includes a cylindrical winding drum portion 2a,
A bobbin 2c, which is formed of synthetic resin and has flanges 2b continuously provided at both ends thereof, is formed by winding an annealed copper wire whose surface is covered with an insulating layer on the outer periphery of the winding body 2a. It The bobbin 2c is provided with a yoke 3 and a fixed iron core 4, which will be described later, and a winding barrel 2
It also has a positioning function of coaxially opposingly arranging a certain distance inside a.

The yoke 3 is a bobbin 2 made of a magnetic metal material.
a cylindrical portion 3a having an outer diameter substantially equal to the inner diameter of the winding drum portion 2a of c,
A collar portion 3b having an outer diameter substantially equal to the outer diameter of the collar portion 2b of the bobbin 2c.
And is integrally formed by cutting or the like. The cylindrical portion 3a has a length that is substantially half the length of the winding drum portion 2a of the bobbin 2c, and a movable element 5 described later is coaxially loosely fitted therein. The yoke 3 is arranged such that the cylindrical portion 3a is inserted from one end side of the winding barrel portion 2a of the bobbin 2c and the collar portion 3b positions it.

The fixed iron core 4 is made of a magnetic metal material and has a cylindrical portion 4a having an outer diameter substantially equal to the inner diameter of the winding barrel portion 2a of the bobbin 2c.
And a collar 4b having an outer diameter substantially equal to the outer diameter of the collar 2b of the bobbin 2c are integrally formed by cutting or the like. The cylindrical portion 4a has a concave facing portion 4c that faces a facing portion of the mover 5 described below, and a shaft hole into which a shaft 6 and a spring 7 described below are inserted. In this fixed iron core 4, the cylindrical portion 4a is inserted from the other end side where the yoke 3 of the winding barrel portion 2a of the bobbin 2c is arranged, and is positioned by the collar portion 4b so that the cylindrical portion 3a of the yoke 3 has a constant distance. Are arranged to face each other. The details of the configuration related to the mover will be described later.

The mover 5 is formed of a magnetic metal material and has a columnar portion 5a having a hole for flesh relief in the center and an opposed portion 5b opposed to the opposed portion 4c of the fixed iron core 4. More specifically, the outer diameter of the cylindrical portion 5a is set to be slightly smaller than the inner diameter of the cylindrical portion 3a of the yoke 3, and the size of the central meat relief hole is set appropriately so that the center of the fixing hole for fixing the shaft 6 will be described later. Have. The facing portion 5b has a truncated cone shape that is continuous with the columnar portion 5a, and has a shaft hole through which a shaft 6 and a spring 7, which will be described later, are inserted, at the center. The mover 5 penetrates the shaft 6 through the fixing hole and is fixed at a predetermined position, and both ends of the shaft 6 are reciprocally supported by a first bearing 8 and a second bearing 9, which will be described later. 3 is coaxially arranged inside the cylindrical portion 3a.

Next, the related structure between the fixed iron core 4 and the mover 5 will be described with reference to FIG. The facing portions 4c and 5b of the fixed iron core 4 and the mover 5 that face each other have respective taper angles set to θ2 for the concave facing portion 4c of the fixed iron core,
When the truncated cone shape of the mover 5 is θ1, the relationship of θ2 <θ1 is established. That is, the distance between the facing portions in the direction orthogonal to the axial direction is formed so as to increase toward the tip side of the mover 5 when the mover 5 is closest to the fixed iron core 4. Further, each of these facing portions is formed at a position where the starting points thereof substantially coincide with each other in the axial direction when the mover 5 comes closest to the fixed iron core 4.

The shaft 6 is made of a non-magnetic metal material such as brass.
The mover 5 has an outer diameter substantially equal to the fixing hole of the mover 5.
It is formed to have a sufficiently longer length and is fixed to the mover 5 so as to be located at a predetermined position. The electromagnetic solenoid 1
Although not shown in the figure, the other end of the shaft 6 projecting downward from is connected and fixed to, for example, an adjusting member for the opening of the valve and driven in the linear direction shown by the arrow 6a,
Controls valve opening.

The spring 7 is a coil spring made of stainless steel or the like, one end of which is brought into contact with the mover 5 and the other end thereof is brought into contact with a first bearing 8 which will be described later, and is loosely fitted to the shaft 6, and the fixed iron core described above is used. It is loosely inserted in the shaft hole formed in 4.

The first bearing 8 is made of synthetic resin and has a disk shape having an outer diameter substantially the same as that of the collar portion 4b of the fixed iron core 4. The shaft 6 reciprocally supports the shaft 6 at its center. It is formed with holes.

The second bearing 9 is made of synthetic resin, has a disk shape having an outer diameter dimension slightly larger than the inner diameter of the cylindrical portion 3a of the yoke 3, and is a circle corresponding to the meat relief hole of the mover 5. It has a columnar protrusion, and is formed with a shaft hole that supports the shaft 6 in a reciprocating manner at the center. This second bearing 9
Is set so that the outer diameter dimension can be press-fitted and fixed to the inside of the cylindrical portion 3a of the yoke 3, and the flat surface 9a is press-fitted and fixed so as to be substantially flush with the surface of the collar portion 3b of the yoke 3, and the spring 7
The mover 5 pressed by is positioned in the axial direction.

The position sensor 10 is in contact with one end of the shaft 6 and outputs an electric signal corresponding to the linear displacement of the shaft 6, and is used for feedback control of the position of the shaft 6 by an external circuit (not shown). To be done. The position sensor 10 uses, for example, a sliding type variable resistor to detect the displacement of the shaft 6 as a change in electric resistance. The position sensor 10 is mounted on a sensor mounting base 10a having a flange portion fixed to the electromagnetic solenoid 1. Be attached.

The casing 11 is made of a magnetic metal material.
A hollow cylindrical portion 11a having an inner diameter slightly larger than the outer diameters of the collar portion 3b of the yoke 3 and the collar portion 4b of the fixed iron core 4, and a first cylindrical member on one end side.
The bearing 8 is formed to have an annular portion 11b on which the peripheral portion of the bearing 8 is placed. The length of the hollow cylindrical portion 11a is slightly larger than the size in which the first bearing 8, the fixed iron core 4, the electromagnetic coil 2, the yoke 3 and the sensor mounting base 10a are stacked, and the tip portion includes the entire inner surface. It becomes the fixing portion 11c for fixing. Further, the casing 11 forms a magnetic path together with the yoke 3, the mover 5, and the fixed iron core 4 when an exciting current flows through the electromagnetic coil 2.

The electromagnetic solenoid 1 is composed of the above-mentioned members, and its assembly is as follows. First, the first bearing 8, the fixed iron core 4, the electromagnetic coil 2 and the yoke 3 are inserted in this order in the casing 11, and then the spring 7 is inserted. , The mover 5 with the shaft 6 fixed at a predetermined position is inserted, and then the second bearing 9 is attached to the yoke 3
The position sensor 10 is inserted after being press-fitted and fixed. Then, the edge of the casing 11 protruding from the sensor mount 10a is pressed with a predetermined pressing force.
Is deformed under pressure so as to press the outside of the end of the.

Electromagnetic solenoid 1 constructed as described above
In the case where the exciting current of the electromagnetic coil 2 is zero, the mover 5 is moved by the spring force of the spring 7 loosely fitted to the shaft 6,
First position shown in FIG. 1 (position farthest from the fixed iron core 4)
It is in. By the exciting current flowing through the electromagnetic coil 2,
A magnetic path is formed by the yoke 3, the mover 5, the fixed iron core 4 provided with a substantially parallel gap, and the casing 11, and the fixed iron core 4 with respect to the mover 5 is formed in the gap.
A magnetic attractive force is applied to the side of. The mover 5 and the shaft 6 are
It moves in the direction indicated by the arrow 6a to a position where this magnetic attractive force and the spring force of the spring 7 are balanced. The mover 5 reaches the second position (position closest to the fixed iron core 4) shown by the alternate long and short dash line in FIG. 1 when the exciting current flowing through the electromagnetic coil 2 has a maximum value in a predetermined range.

FIG. 3 is a graph of the relationship between the amount of change in the gap between the facing portions in the axial direction (hereinafter referred to as the stroke) and the magnetic attractive force, that is, the measured data of the stroke-magnetic attractive force characteristics. This graph shows the concave facing portion 4 of the fixed iron core 4 of the electromagnetic solenoid 1 according to the embodiment of the present invention shown in FIG.
The taper angle θ2 of c is constant at 60 degrees, and the taper angle θ1 of the truncated cone-shaped facing portion 5b of the mover 5 is changed as a parameter, which is based on actual measurement data. Regarding the value of this parameter, θ1 = 60 degrees is θ1 in the case of the conventional example.
= 65 degrees and θ1 = 70 degrees show the case of the embodiment of the present invention. The taper angle θ1 is obtained by changing the starting point for forming the taper on the tip end surface of the mover 5. When θ1 = 70 degrees, when the mover 5 comes closest to the fixed iron core 4, the end point of the tapered surface of the mover substantially coincides with the start point of the tapered surface of the fixed iron core in the axial direction.

As is clear from the measured data, in the case of the conventional example, the magnetic attraction is about 50 N in the stroke of 2 mm or less, that is, near the first position of the mover 5, and the average value of 43.5 N in the stroke of 2 mm or more. About 15 compared to
It is about% high. That is, in the case where the fixed iron core 4 and the mover 5 have the same taper angles in the facing portions, the magnetic flux flows in the concave portion 4c due to the excitation current flowing when the mover 5 is in the vicinity of the first position. Between the facing portions of the facing portion 5b and the facing portion 5b, the unevenness is generated in the upper edge of the concave portion 4c of the fixed iron core 4 closest to the facing portion 5b, and a large magnetic attraction is exerted. The generation of this magnetic flux is a major factor in increasing the fluctuation of the stroke-magnetic attraction characteristic of the electromagnetic solenoid.

When the truncated cone taper angle θ1 in the embodiment of the present invention is 65 degrees, the magnetic attractive force is
The average of strokes from 1mm to 7mm is 4
At 3.7 N, the maximum fluctuation range is 2.3 N, and the fluctuation ratio is about ± 2.6%, which is a stable value. That is, the distance between the facing parts of the fixed core 4 and the mover 5 facing each other in the axial direction and the direction orthogonal to each other is such that when the mover 5 is closest to the fixed core 4, the tip of the mover 5 is When the mover 5 is in the vicinity of the first position, the magnetic flux formed between the concave facing portion 4c and the frustoconical facing portion 5b is formed such that the magnetic flux becomes larger toward the side. Dispersion between the opposing portions occurs almost evenly, and the difference between the magnetic attraction and the case where the stroke is large is eliminated. As a result, it is possible to achieve a magnetic attractive force that does not fluctuate over the entire stroke of the valve operation, so that a proportional operation by an exciting current can be realized.

Further, in the embodiment of the present invention, when the truncated cone taper angle θ1 is set to 70 degrees, the magnetic attractive force is 48 N on average between 1 mm and 7 mm of the stroke, and the maximum fluctuation range is 1. At 9 N, the variation ratio is about ± 2%, which is a stable value similar to θ1 = 65 degrees, and it can be seen that the average value is about 10% larger. That is, when the mover 5 is closest to the fixed iron core 4, the facing part is formed at a position where the starting points of the facing parts are substantially coincident with each other in the axial direction. In the flow of current, the magnetic flux
The concave facing portion 4c and the truncated cone-shaped facing portion 5b are dispersed between the facing portions and generated substantially evenly, and the magnetic resistance between the facing portions is reduced, so that the magnetic efficiency can be improved. Becomes As a result, when θ1 is set to 70 degrees, a higher magnetic attractive force is obtained compared to when θ1 is set to 65 degrees, so that driving with a lower current becomes possible.

In the embodiment of θ1 = 70 degrees, the respective facing portions are formed so that their starting points are substantially aligned in the axial direction when the mover 5 is closest to the fixed iron core 4. Even if the position is different, the magnetic efficiency is reduced, but the influence on the stabilization of the magnetic attractive force is small and does not pose any problem. In addition, the fixed iron core 4
The concave taper angle θ2 of 60 is set to 60 degrees, and the actual measurement data is shown up to 70 degrees using the truncated cone taper angle θ1 of the mover 5 as a parameter.
2 and θ1 should be set in the condition of the magnetic metal material of the mover 5 and the fixed iron core 4, or in the setting of the distance between the facing parts in the direction orthogonal to the axial direction when the mover is closest to the fixed iron core. But not limiting.

[0026]

In the electromagnetic solenoid according to the first aspect of the present invention, since the change in the magnetic attractive force can be reduced in the entire stroke of displacement of the mover, proportional operation can be performed by the exciting current over the entire stroke of operation. .

The electromagnetic solenoid according to claim 2 is
In addition to the effect of the first aspect, a high magnetic attractive force can be obtained over the entire stroke of displacement of the mover, so that driving with a low current becomes possible.

[Brief description of drawings]

FIG. 1 is a front sectional view of an embodiment of the present invention.

FIG. 2 is a partially enlarged view of a facing portion that is a main portion thereof.

FIG. 3 is a characteristic diagram of its stroke-magnetic attraction characteristic.

[Explanation of symbols]

 2 Electromagnetic coil 3 Yoke 4 Fixed iron core 5 Mover 6 Shaft 7 Spring 8 1st bearing 9 2nd bearing 10 Position sensor 11 Casing

Claims (2)

[Claims] 1. An electromagnetic coil, a yoke and a fixed iron core whose magnetization is controlled by an exciting current flowing through the electromagnetic coil, and a mover arranged so as to be movable coaxially by receiving a magnetic attractive force from the fixed iron core. And a spring that opposes the magnetic attraction between the fixed iron core and the mover, and the facing portions of the fixed iron core and the mover that face each other have a frustoconical shape for the mover and a fixed iron core for the opposite direction. In the electromagnetic solenoid with a concave shape that substantially corresponds to that, the distance between the facing parts in the direction orthogonal to the axial direction is formed so as to increase toward the tip side of the mover when the mover is closest to the fixed iron core. An electromagnetic solenoid characterized by being formed. 2. The electromagnetic solenoid according to claim 1, wherein each of the facing portions is formed at a position where a starting point thereof substantially coincides with an axial direction when the mover is closest to the fixed iron core. .