JPH05292730A - Linear actuator - Google Patents

Abstract

PURPOSE:To obtain a linear actuator which can obtain a large propulsion force by fixing adjacent wires of a coil with resin, and forming an integral cylinder member durable against a magnetic force to be used at the time of operating. CONSTITUTION:A coil 66 is fixed at adjacent wires with varnish to be formed in an integral cylinder. A shaft 32, coil supports 50, 52, coils 66, 68, etc., constitute a first member, and a permanent magnet 18, an outer peripheral side yoke 14, an inner peripheral side yoke 22, a retainer 20, etc., constitute a second member. Grooves 38, 40 are formed on the second member, and a closed magnetic path R for circulating the magnet 18, the yoke 14, the groove 38, the yoke 22, the groove 40, the yoke 14, the magnet 18 is formed. When currents flow to the coils 66, 68, propulsion forces based on amplitudes of the flowing currents are generated, but since center lines are the same, the first member is relatively moved to the second member by a force combined with the two propulsion forces to move a spool.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear actuator.

[0002]

2. Description of the Related Art Linear actuators are used in electromagnetic control valves and the like because they have high responsiveness and excellent linearity. The present applicant has proposed a spool type electromagnetic pressure control valve using a linear actuator in Japanese Patent Application No. 3-177664.
Disclosed in the specification. The spool-type electromagnetic pressure control valve described in this specification controls the position of the spool based on the current supplied to the coil portion of the linear actuator. This linear actuator is
(A) A first member including a coil formed by winding a wire and a support cylinder that supports the coil from its inner peripheral side,
(B) A magnetic material portion is provided, and at least one groove portion into which the coil is movably fitted in the same direction as the center line of the coil is formed, and a part of the magnetic material portion is formed. A second member provided with at least one magnetism generating part, wherein the magnetism generating part forms a closed magnetic path intersecting with the groove; and (c) the center of the coil of the second member and the first member. And guide means for guiding relative movement in a direction substantially parallel to the line. This linear actuator will be described with reference to FIG.

A cylindrical yoke 212 is immovably fixed to the inner peripheral surface of the cylindrical housing 210. A through hole 214 is formed in the center of the yoke 212,
In the through hole 214, the stepped shaft 216 has the large diameter portion 21.
7 is slidably fitted through bearings 218 and 220. Further, an annular groove 222 having a width h is formed in the yoke 212, and the bobbin 22 is formed in the groove 222.
The cylindrical portion 225 of No. 4 is fitted so as to be movable in the axial direction. The bobbin 224 has a bottomed cylindrical shape, and a wire 226 having a length L is wound around the cylindrical portion 225 to form a coil 227.
(See FIG. 7) are formed. Further, a through hole 229 is formed in the center of the bottom portion 228 of the bobbin 224.

The large-diameter side end of the shaft 216 is projected from the through hole 214 and abuts on the bottom surface of the housing 210. Further, the other end is a small diameter portion 230, a bobbin 224 is fitted in the through hole 229 in the middle portion thereof, and a bottom portion 228 has a step portion 232 between the large diameter portion 217 of the shaft 216 and the small diameter portion 230 and a nut 234. It is fixed by being sandwiched between and. Therefore, the bobbin 224 and the shaft 216 move integrally.

The end of the small-diameter portion 230 is the housing 2
The through hole 236 formed on the end surface of the through hole 10 is engaged with a spool (not shown). Therefore, axis 2
The spool is moved by the movement of 16 and the bobbin 224, and the movement force of the spool is controlled by the control of the movement force of the shaft 216 and the bobbin 224.

An annular permanent magnet 240 is provided on the outer peripheral side of the groove 222 of the yoke 212.
0, the yoke 212, the groove 222, the yoke 212, and a closed magnetic circuit P that circulates through the permanent magnet 240. Groove 222
A magnetic field having a magnetic flux density B is generated at.

In the linear actuator constructed as described above, when current is supplied to the coil 227,
Propulsive force F based on the magnitude of the current I is generated, and the integrated bobbin 224 and shaft 116 are moved in the direction of arrow Q and the spool is moved. The propulsive force F in this case is represented by the formula F = B · I · L.

[0008]

However, in the linear actuator described in the above specification, the propulsive force F is
Could not be made large enough. As is clear from the above equation, in order to increase the propulsive force F, the magnetic flux density B,
It is necessary to increase at least one of the current I and the length L of the wire forming the coil, but it was difficult to make them sufficiently large in the conventional linear actuator for the following reasons.

First, regarding the magnetic flux density B, in the above linear actuator, as shown in FIGS.
(1 will be described later), the magnetic flux has reached a saturated state in the portion A surrounded by the broken line in the yoke 212 shown in (1), so that the magnetic flux cannot be further increased and the magnetic flux density B in the groove 222 should be increased. I can't.

Secondly, regarding the current I, as the amount of heat generated by the coil increases as the current I is increased, the current I cannot be increased in consideration of the amount of heat generated by the coil.

Thirdly, regarding the length L of the wire forming the coil, the groove 222 has a cylindrical portion 225 and the coil 2
27 is inserted, and a clearance of a predetermined size is required between the cylindrical portion 225 and the wall surface of the groove 222 and between the coil 227 and the wall surface of the groove 222. The space that can be occupied is relatively small. The space that can be occupied by the coil 227 in the groove 222 is only the annular portion having the radial thickness e1 shown in FIG. The thickness e1 is the thickness shown in the following equation. e1 = h-f1-f2-f3 Here, f1: clearance required between the inner peripheral surface of the tubular portion 225 and the wall surface of the groove 222 f2: necessary between the outer peripheral side of the coil 227 and the wall surface of the groove 222 Clearance f3: Thickness of the cylindrical portion 225. In this way, the space that the coil 227 can occupy is limited, and the thickness of the wire forming the coil is inevitably determined by the relationship with the current. Therefore, the number of turns is limited and the length of the wire is limited. Of.

Against the background of the above circumstances, the present invention has an object to obtain a linear actuator which can obtain a propulsive force as large as possible.

[0013]

In order to solve this problem, the gist of the present invention resides in the above (a) first member and (b) second member.
In a linear actuator including a member and (c) guide means, the coils themselves are fixed to each other by a resin, so that the coil itself is an integral tubular member capable of withstanding a magnetic force applied when the linear actuator operates. , Omitting the support tube.

[0014]

By doing so, the coil support cylinder, which is indispensable in the conventional linear actuator, can be omitted. As a result, the coil cannot be inserted into the groove of the second member but only the coil is inserted into the groove. Therefore, the space occupied by the coil in the groove is increased, and the length of the wire forming the coil is increased. You can

[0015]

According to the linear actuator of the present invention, the wire forming the coil can be lengthened without widening the groove portion of the second member, so that the propulsive force can be increased. Further, when the length of the wire forming the coil is the same as that of the conventional linear actuator, the width of the groove can be narrowed by omitting the support cylinder, and the magnetic resistance of the groove becomes small. It is possible to reduce the magnetomotive force of the magnetism generating portion, and to reduce the size of the permanent magnet and the magnetic material portion.

Furthermore, the mass of the first member can be reduced by omitting the support cylinder, and the responsiveness can be improved when the first member is moved with respect to the second member. Further, since the linear actuator of the present invention can generate a larger propulsive force than the conventional linear actuator, it can be downsized when the propulsive force is the same as the conventional one.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a linear actuator of a spool type electromagnetic pressure control valve will be described in detail below with reference to the drawings. In FIG. 1, 10 and 12 are bottomed cylindrical housings, and a cylindrical outer peripheral yoke 14 is sandwiched between a shoulder surface 16 of the housing 10 and the housing 12 and fixed. An annular permanent magnet 18 is provided at an intermediate portion of the outer peripheral yoke 14, the outer peripheral side of the permanent magnet 18 is fitted into the housing 10, and the inner peripheral side of the permanent magnet 18 has a T-shaped cross section. The inner yoke 22 is fixed via the retainer 20. Since the retainer 20 is made of a non-magnetic material, the inner yoke 22 and the outer yoke 14 are magnetically insulated. A through hole 26 is formed in the center of the inner yoke 22, and a stepped shaft 32 is slidably fitted in the through hole 26 at its large diameter portion 34 via bearings 28 and 30. There is.

The outer peripheral side yoke 14 and the inner peripheral side yoke 22 are formed by fixing a plurality of annular members made of magnetic material. In addition, the outer peripheral yoke 14 and the inner peripheral yoke 2
An annular gap between the two is partitioned by a retainer 20, and grooves 38, 40 are formed on both sides of the retainer 20.

The linear actuator has disk-shaped coil supporting members 50 and 52. A mounting hole 54 is formed at the center of the coil support member 50, and a plurality of weight reducing holes 56 are formed at positions radially separated from the mounting hole 54. An annular notch 58 is formed on the outer peripheral surface. Similarly, the mounting holes 60,
A weight reduction hole 62 and a cutout 64 are formed.

Also, coils 66 and 68 formed by winding wires 65 of length L1 (see FIG. 6) in opposite directions are fixed to the notches 58 and 64, respectively. Therefore, although the coils 66 and 68 are connected in series to supply a current, the directions of the propulsive forces generated in the coils 66 and 68 are not the opposite directions but the same directions. The center lines of the coils 66 and 68 are the same as the center line of the shaft 32, and the dimensions of both coils 66 and 68 are the same. As will be described later, the coils 66 and 68 are formed by winding a wire 65 coated with varnish, and thus the wires 65 adjacent to each other are fixed by a resin, and form an integral tubular shape. is doing. The coils 66 and 68 are bonded to the cutouts 58 and 64 of the coil support members 50 and 52 with resin.

Here, a method of manufacturing the coil 66 will be described with reference to FIGS.
It will be explained based on. The coil 68 is formed by a method similar to that of the coil 66, and a description thereof will be omitted. In FIG.
70 is a jig. The jig 70 has a generally cylindrical shape, and an internal thread hole 74 is formed in the center of the end surface 72 of the jig 70, and two pins 76 are fixed at positions diametrically spaced from the internal thread hole 74. And coil support 5
When 0 is brought into contact with the end surface 72, the mounting hole 54 of the coil supporting member 50 and the female screw hole 74 of the jig 70 coincide with each other, and the pin 76 is fitted into the two weight reducing holes 56. ..

An annular notch 78 having a depth e2 in the radial direction is formed in a portion of the outer peripheral surface of the jig 70 on the end face 72 side. The notch 78 is formed on the bottom surface of the notch 78 and the coil supporting member 5.
The bottom surface of the notch 58 of 0 is located on the same cylindrical surface. The wire 65 is wound around the space formed by the notches 78 and 58 to form the coil 66.

After the release agent is applied to the notches 78 of the jig 70 and the coil support member 50 is fixed by the bolts 80, the wire 65 coated with varnish is wound around the notches 78 and 58. After the varnish is dried, the coil support material 50 is removed from the jig 70. As a result, the coil 66 shown in FIG. 6 is formed, and at the same time, the coil 66 is fixed to the notch 58 of the coil supporting member 50 (see FIG. 4).

The coil 66 is an integral cylindrical body because the wires 65 adjacent to each other are fixed by a varnish. Therefore, the support cylinder for supporting the coil 66, which is conventionally required, from the inner peripheral side thereof, that is, the cylindrical portion 225 in FIG. 7 is unnecessary. Therefore, the coil 66 is
The thickness e2 of the space that can be occupied inside (hereinafter,
The thickness of the coil) is the length shown in the following equation, which is thicker than the thickness e1 by the thickness f3 of the tubular portion 225. e2 = h-f1-f2 (= e1 + f3) According to the above equation, the thickness e2 of the coil 66 is (1 + f3 / e1) times the thickness e1 of the coil 227. That is, the length L1 of the wire 65 forming the coil 66 is set to the coil 227.
Of the length L of the line 226 forming (1 + f3 / e1)
It can be doubled.

Strictly speaking, the increase rate of the thickness e2 of the coil 66 with respect to the thickness e1 of the coil 227 is not the same as the increase rate of the length L1 of the line 65 with respect to the length L of the line 226. For example, since the wire 65 is overlapped and wound at a position between the previously wound wires as shown in FIG. 6, the thickness of one layer may be smaller than the diameter of the wire 65, and the wire 65 may also be formed. It is necessary to start winding from the coil supporting member 50 side and to finish winding on the coil supporting member 50 side, so that there are various delicate circumstances such as increasing the number of layers by an even number. In this embodiment, the thickness e2 of the coil 66 is
Is about 1.24 times the thickness e1 of the coil 227, and the wire 6
The length L1 of 5 is about 1.24 times the length L of the wire 226.

It is desirable that the varnish be capable of satisfactorily fixing the wires 65 to each other and have oil resistance. This is because the linear actuator is installed in the brake fluid. The varnish of this example is obtained by dissolving a heat-resistant alkyd resin in solvent naphtha.

Both ends of the shaft 32 have small diameter portions 88 and 9 respectively.
0, and the coil support member 50 is attached to the small diameter portion 88.
4, the large diameter portion 34 and the small diameter portion 88 of the shaft 32 are fitted together.
It is fixed by being sandwiched between the stepped portion 92 and the nut 94. Further, the end of the small diameter portion 88 is engaged with a spool (not shown) through a through hole 95 formed in the end surface of the housing 12.

Similarly, the small diameter portion 90 has a coil supporting member 52.
Are fitted in the mounting hole 60, and the step portion 96 and the nut 98 are fitted.
It is sandwiched between and fixed. In this way, the shaft 32
Coil support members 50 and 52 are fixed to the coil, and the spool is moved along with the movement of the shaft 32, the coil support members 50 and 52, and the coils 66 and 68.

As is apparent from the above description, the shafts 32,
The coil supporting members 50, 52, the coils 66, 68 and the like constitute a first member, and the permanent magnet 18, the outer peripheral side yoke 14, the inner peripheral side yoke 22, the retainer 20 and the like constitute a second member. Grooves 38 and 40 are formed in the second member, and the permanent magnet 18, the outer peripheral side yoke 14, the groove 38, and the inner peripheral side yoke 2 are formed.
2, a closed magnetic circuit R that circulates through the groove 40, the outer peripheral yoke 14, and the permanent magnet 18 is formed. The bearings 28 and 30 form a guide means.

In the linear actuator constructed as described above, when current is supplied to the coils 66 and 68, a propulsive force is generated in the coils 66 and 68 based on the magnitude of the supplied current I. Since the center lines of the coils 66 and 68 are the same, the first member is moved relative to the second member by a force F2 that is a combination of these two propulsive forces, and the spool (not shown) is moved accordingly.

Since the coils 66 and 68 have sufficient strength and rigidity by themselves, they are not deformed by the magnetic force of the closed magnetic circuit R formed by the permanent magnet 18. In addition, the coils 66, 68 and the coil supporting member 50,
Since the 52 is well adhered, the coils 66, 68
Does not come off from the coil supporting members 50 and 52.

Further, the brake fluid is used as the coil support material 5.
Since it can satisfactorily flow through the weight reducing holes 56 and 62 of 0.52, the first member can move lightly. The coil 6
The length L1 of the line 65 forming 6, 68 is set to the conventional line 226.
When the length is the same as the length L, it is possible to reduce the weight of the first member, and the effect of improving the responsiveness can be obtained.

Table 1 shows the results of comparison of the propulsive forces of the linear actuator of this embodiment and the conventional linear actuator.
Shown in. Here, each numerical value in the conventional linear actuator is set to 1.

[0034]

[Table 1]

As is clear from Table 1, the linear actuator of this embodiment can have a larger propulsive force than the conventional linear actuator. The first reason is that two grooves are formed, and the second reason is that the wire forming the coil is lengthened.

First, the first point will be described. Since the magnetic resistance increases as the number of grooves in the closed magnetic circuit increases, the magnetic flux density of the closed magnetic circuit R in the linear actuator of this embodiment becomes smaller than the magnetic flux density of the closed magnetic circuit P in the conventional linear actuator. Therefore, while the magnetic flux density was saturated in the closed magnetic circuit P, the magnetic flux density in the closed magnetic circuit R did not reach the saturated state, and the magnetic flux density B1 of the grooves 38 and 40 was greater than the magnetic flux density B of the groove 222. Although it will be low, the amount of decrease will be small because the saturated state is avoided.

FIG. 2 shows the result of calculation of the distribution of the magnetic flux density in the first member of the linear actuator of the present invention.
Shown in. In the figure, the dash-dotted line has a magnetic flux density of 1.0 to 1.3 Tesla, the dash-dotted line has 0.3 to 1.0 Tesla, and the broken line has 0.1.
Each of the magnetic flux density lines of ~ 0.3 tesla is shown.
The magnetic flux density is 1.0 to 1.3 tesla even in the portion E surrounded by the broken line, which has the largest magnetic flux density, and the magnetic flux has not reached the saturation state. The saturation magnetic flux density of the magnetic material used in this embodiment and the conventional linear actuator is about 1.4 tesla.

On the other hand, FIG. 11 shows the result of calculation of the distribution of the magnetic flux density of the yoke 212 of the conventional linear actuator. In FIG. 11, the groove 40 of the linear actuator of this embodiment is filled with a member made of a magnetic material, and the inner peripheral side yoke 22 is
Since the calculation is performed assuming that the outer peripheral yoke 14 and the outer peripheral yoke 14 are integrally formed, the shape of the yoke in FIG. 11 is slightly different from the shape of the yoke 212 in FIG. 10. However, since it is the same in that one groove is provided in the closed magnetic circuit, it is considered that these show a similar distribution of magnetic flux density.

The solid line in FIG. 11 has a magnetic flux density of 1.7 to 1.9.
Tesla, the one-dot chain line shows 1.0-1.7 Tesla, the two-dot chain line shows 0.3-1.0 Tesla, and the broken line shows 0.1-0.3 Tesla, respectively. The magnetic flux density in the A portion is 1.7 to 1.9 Tesla, but in reality, the magnetic flux has reached a saturation state, which is a value of about 1.4 Tesla. Therefore, even if the magnetic resistance is increased by increasing the number of grooves, it is compensated by the fact that the magnetic flux is no longer saturated, and the decrease amount of the magnetic flux density is small.

Actually, the magnetic flux density B1 at the points D1 and D2 in the grooves 38 and 40 is about 0.46 tesla, whereas the magnetic flux density B at the point D3 in the groove 222 is 0.61 tesla. Cage, groove 3 of the linear actuator of the present embodiment
The magnetic flux density B1 of 8, 40 is about 0.75 times the magnetic flux density B of the groove 222 of the conventional linear actuator (0.46 /
0.61).

Next, the second point will be described. As described above, the length L1 of the wire 65 forming each of the coils 66 and 68 is about 1.24 times the length L of the wire 226 of the conventional coil 227, and two coils are further provided. Therefore, the length of the wire forming the coil of the linear actuator of the present embodiment is 2.
That is 48 times (1.24 × 2).

As described above, in the linear actuator of this embodiment, although the magnetic flux density is lower than that of the conventional linear actuator, the line forming the coil can be made longer. 1.86 times the propulsive force F in the actuator (0.
75 × 2.48).

A little explanation of the varnish for hardening the coils 66 and 68 will be supplemented. The varnish that can be used in the practice of the present invention must satisfy two conditions: that it can fix the wires 65 to each other satisfactorily and that it has oil resistance. .. Table 2 shows the results of performance tests of various varnishes.

[0044]

[Table 2]

The test of the fixing strength of the wire 65 by the resin contained in the varnish was conducted by using the coil 66 shown in FIG. 4 and the coil supporting member 50 supporting the coil 66 in parallel with the center line of the coil 66. Force T toward material 50
Was gradually added, and the magnitude of the force T when the coil 66 was plastically deformed was measured. The better the adhesiveness between the resin contained in the varnish and the wire 65, the less likely the coil 66 is to undergo plastic deformation.

Next, in the oil resistance test of the varnish, after immersing the coil 66 shown in FIG. 4 and the coil supporting member 50 supporting it in the brake fluid for 1 hour, the magnitude of the force T is measured in the same manner as above. Went by. If the oil resistance is excellent, the fixing strength does not decrease even after immersion.

In Table 2, the circles indicate that the force T is 98.
N (10 kgf) or more, and it is determined that the linear actuator of the present embodiment can be used. On the contrary, the mark X indicates that the magnitude of the force T is smaller than 98 N, and it is determined that the linear actuator cannot be used. It was done.

As is clear from Table 2, it is understood that the heat-resistant alkyd resin / sorbet naphtha can be used in the present linear actuator. The unsaturated polyester has excellent adhesion to the wire 65, but has poor oil resistance. The ester bond in the unsaturated polyester is easily hydrolyzed by the brake fluid. Further, both the phenol resin / alcohol and the epoxy resin / cellosolve xylene have a weak adhesive strength with the wire 65 and cannot be used in the present linear actuator.

FIG. 5 shows another embodiment of the present invention. The present embodiment is intended to further increase the fixing strength between the coil supporting member and the coil. In the above embodiment, the coil supporting members 50 and 52 are formed with the notches 58 and 64, and the coils 66 and 68 are fixed to the notches 58 and 64, respectively, but in the present embodiment, the coil supporting member 102 is used. A notch 104 similar to the notch 58 of the above-described embodiment is formed on the outer peripheral surface of the, and an annular groove 106 is further formed at the corner of the notch 104. The coil supporting member 102 is fixed to the jig 70 in the same manner as described above to form the coil 66. The groove 106 is also filled with varnish in advance. After the varnish is solidified, a part of the coil 66 is in a state of digging into the coil supporting material 102.
The fixing strength between the coil 2 and the coil 66 can be increased.

In the above embodiment, the coils 66,
Although 68 is connected in series so that the same amount of current is supplied, it is not always necessary to do so, and it is also possible to individually control the currents of the coils 66 and 68. Is. For example, it is possible to allow a current to flow through only one coil, or to allow different currents to flow through the respective coils. And
In the latter case, this linear actuator is used for a spool type electromagnetic control valve of a vehicle brake system so that one coil is supplied with a current based on a signal from a pedaling force sensor and the other coil is provided with an acceleration. If the current is supplied based on the signals of the sensors, the position of the spool can be controlled based on the outputs of both sensors.

Further, although two grooves are provided in series in the above embodiment, the wire forming the coil can be lengthened even if the number of grooves is one, so the propulsive force is increased correspondingly. can do. Further, the present invention can be applied whether two grooves are provided in parallel in the coaxial direction or not only two grooves but three or more grooves are provided. Further, the coil support materials 50, 52 and the like may be fixed, and the outer peripheral side yoke 14, the inner peripheral side yoke 22 and the like may be moved.

Another jig used to carry out the present invention is shown in FIGS. This jig facilitates removal of the coil support material 50 and the coil 66 after forming the coil. The jig 110 includes a main body 112 and a collet 11.
6 and an outer shell 118. The outer peripheral surface of the main body 112 is tapered, the large diameter side end surface 120 is provided with a female screw hole 122 and two pins 124, and the small diameter side end face 125 is formed with a female screw hole 126 at the center thereof. ing.

The collet 116 is a generally cylindrical member having a bottom, the inner peripheral surface of which is a tapered surface and the outer peripheral surface of which is a cylindrical surface, and is fitted to the outside of the main body 112. Eight slits 130 are inserted from the open end 128 into the collet 116 to form eight movable parts 132.
Are coupled by the coupling portion 134. A female screw hole 136 is formed in the central portion of the coupling portion 134 of the collet 116.

The outer shell 118 has a stepped thin-walled tubular shape, and the small diameter portion 140 thereof is the movable portion 132 of the collet 116.
Is fitted on the outside of. An inward flange 146 provided on the large diameter portion 142 side is fixed to the joint portion 134 of the collet 116.

The main body 112 and the collet 116 are connected by a screw member 148. The screw member 148 includes a left-hand threaded portion 150 and a right-handed threaded portion 152.
0 is screwed into the female screw hole 136 of the collet 116, while the right screw portion 152 is screwed into the female screw portion 126 of the main body 112. Therefore, if the screw member 148 is turned to the right, the coupling portion 134 of the collet 116 approaches the main body 112, and if turned to the left, it separates from the main body 112.

The connecting portion 134 of the collet 116 is the main body 11
In the state where the screw member 148 is tightened until it comes into contact with 2, the body 112 expands the diameter of the collet 116, and the collet 116 expands the diameter of the small diameter portion 140 of the outer shell 118. In this state, the diameter of the small diameter portion 140 and the diameter of the bottom surface of the cutout 58 of the coil support member 50 are made equal.
Further, when the screw member 148 is turned counterclockwise and the connecting portion 134 of the collet 116 is pushed away from the main body 112, the collet 116 is reduced in diameter and the small diameter portion 140 of the outer shell 118 is permitted to be reduced in diameter.

When the jig 110 is used, the collet 116 and the small-diameter portion 140 are expanded, a mold release agent is applied to the surface of the small-diameter portion 140, and the coil supporting member 50 is fixed by the bolt 156. Fix it. After that, the coil 66 is formed in the same manner as in the above embodiment.

After the varnish has solidified, the bolt 156 is removed, and the screw member 148 is turned counterclockwise to reduce the diameter of the collet 116 and the small diameter portion 140, so that a gap is created between the small diameter portion 140 and the coil 66, The support member 50 and the coil 66 can be easily removed from the jig 110.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a linear actuator that is an embodiment of the present invention.

FIG. 2 is a distribution diagram of magnetic flux density of the yoke of the above-described embodiment.

FIG. 3 is a cross-sectional view of a jig for forming the coil of the above embodiment.

FIG. 4 is a cross-sectional view of a coil support member and a coil of the above embodiment.

FIG. 5 is a sectional view of a coil support member according to another embodiment of the present invention.

FIG. 6 is a partial cross-sectional view of the coils of the above-described embodiments.

FIG. 7 is a partial cross-sectional view of a coil in a conventional linear actuator.

FIG. 8 is a cross-sectional view of another jig used for implementing the present invention.

FIG. 9 is a sectional view taken along the line KK in the above embodiment.

FIG. 10 is a sectional view of a conventional linear actuator.

FIG. 11 is a distribution diagram of magnetic flux density in the conventional linear actuator.

[Explanation of symbols]

 14 Outer peripheral side yoke 18 Permanent magnet 22 Inner peripheral side yoke 28 Bearing 30 Bearing 38 Groove 40 Groove 50 Coil support material 52 Coil support material 65 Wire 66 Coil 68 Coil

Front Page Continuation (72) Inventor Mitoku Kadowaki, Toyota City, Toyota City, Aichi Prefecture 1 Toyota Motor Co., Ltd. (72) Inventor, Koji Kazuoka, Toyota City, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd.

Claims (1)

[Claims] 1. A first coil comprising a coil formed by winding a wire, and a support cylinder for supporting the coil from an inner peripheral side thereof.
A member and a magnetic material portion, and at least one groove portion into which the coil is movably fitted in the same direction as the center line of the coil is formed in the magnetic material portion, and a part of the magnetic material portion is formed. A second member provided with at least one magnetism generating part and forming a closed magnetic path intersecting with the groove part by the magnetism generating part; and a center line of the coil of the second member and the first member. In a linear actuator including guide means for guiding relative movement in parallel directions, by fixing the adjacent wires of the coil with resin, the coil itself can withstand the magnetic force that acts when the linear actuator operates. A linear actuator, characterized in that the supporting cylinder is omitted as an integral cylindrical member to be obtained.