JP5712419B2 - solenoid - Google Patents

Description

  The present invention relates to a solenoid, and more particularly to a solenoid that requires a certain thrust.

  For solenoids with a short stroke that the movable magnetic pole attracts instantaneously to the fixed magnetic pole, it takes time to attract the movable magnetic pole. That is, a solenoid with a long stroke has a strong thrust (attraction force) during operation of the movable magnetic pole. Many things require stability at the same time. In particular, in the proportional solenoid, the length of the control stroke area and the strength and stability of the suction force in the control stroke area are often required at the same time.

  Therefore, various structures have been proposed in order to improve the suction force and the like in a solenoid having a long stroke. FIG. 6 is a cross-sectional view showing the structure of a solenoid according to the prior art. In FIG. 6, 50 is a solenoid, 51 is a fixed yoke, 52 is a convex portion, 53 is a movable yoke, 54 is a protruding portion, 54a is an outer peripheral surface, 54b is an inner peripheral surface, 54c is an end surface, 55 is a central portion, and 56 is The tip.

  FIG. 6 shows a solenoid disclosed in Japanese Patent Application Laid-Open No. 2006-222199. As shown in FIG. 6, an annular convex portion 52 protruding in the axial direction is formed at the edge portion of the distal end surface of the fixed yoke 51 of the solenoid 50, and the outer peripheral surface of this convex portion 52 is on the distal end side. It is formed in a tapered shape inclined at a predetermined angle so as to be located radially inward as it goes. In addition, the movable yoke 53 has a protruding portion 54 that protrudes toward the fixed yoke 51 at the edge of the front end surface. The protruding portion 54 is formed in an annular shape over the entire circumference of the movable yoke 53, and the outer peripheral surface 54 a extends substantially parallel to the axis AL of the movable yoke 53. On the other hand, the inner peripheral surface 54b of the protruding portion 54 is formed in a tapered shape that is inclined at a predetermined angle θ with respect to the axis AL of the movable yoke 53 so as to be positioned radially outward as it goes toward the distal end side. An end face 54 c extending in a direction substantially orthogonal to the axis AL of the movable yoke 53 is formed at the tip of the projecting portion 54.

  As described above, in the solenoid 50 in which the annular protrusion 54 with the inner peripheral surface 54 b inclined is formed at the tip of the movable yoke 53, the shaft extends from the end surface 54 c of the protrusion 54 of the movable yoke 53 to the tip of the fixed yoke 51. The axial magnetic flux Φ1 flowing in the direction is smaller than the radial magnetic flux Φ2 flowing in the radial direction from the outer peripheral surface 54a of the protrusion 54 of the movable yoke 53 to the inner peripheral surface of the convex portion 52 of the fixed yoke 51 (Φ1 <Φ2 ). This is because the inner peripheral surface 54b of the protruding portion 54 is inclined so as to be positioned radially outward as it goes toward the fixed yoke 51, so that the direction of the magnetic flux flowing through the protruding portion 54 changes radially outward. This is because the distance between the central portion 55 at the front end of the movable yoke 53 and the front end 56 of the fixed yoke 51 is larger than the conventional one.

  According to the above configuration, the thrust can be increased without increasing the size of the solenoid 50, but the stability of the suction force can be increased and the length of the control stroke region cannot be further increased.

JP 2006-222199 A

  In order to solve the above problems, an object of the present invention is to provide a solenoid having a structure capable of increasing the stability of thrust and further extending the length of a control stroke region.

  According to the first aspect of the present invention, the coil, the fixed magnetic pole disposed in the vicinity of the coil and formed with the cylindrical portion, and the distal end side enters the cylindrical portion when the coil is energized, and the fixing is performed. In the solenoid having a movable magnetic pole attracted to the magnetic pole, the fixed magnetic pole has a first region at least within a first distance from a distal end portion of the cylindrical portion of the inner peripheral surface of the cylindrical portion. A second region that is formed to be parallel to the central axis of the movable magnetic pole and is within a second distance from the tip of the cylindrical portion of the outer peripheral surface of the cylindrical portion is the movable magnetic pole. It is formed so that it may become a field parallel to a central axis, and it exceeds the 2nd distance from the tip part of the cylindrical part among the peripheral surfaces of the cylindrical part, and the tip part of the cylindrical part A third region within a third distance from the wall of the cylindrical portion is the proximal end of the cylindrical portion It is formed on the inclined surface so as to increase gradually toward a solenoid which the first distance is equal to or longer than the second distance.

  According to a second aspect of the present invention, there is provided the auxiliary magnetic pole according to the first aspect of the invention, wherein the auxiliary magnetic pole is formed in the vicinity of the coil and has a cylindrical portion into which the movable magnetic pole is slidably inserted. Furthermore, it is a solenoid characterized by having.

  The invention according to claim 3 is the solenoid according to claim 2, wherein the auxiliary magnetic pole has the cylindrical portion extending toward the cylindrical portion of the fixed magnetic pole. It is.

  According to a fourth aspect of the present invention, in the invention according to the third aspect, the auxiliary magnetic pole has a stepped portion such that a thickness of a portion of the fixed magnetic pole near the cylindrical portion is reduced on the cylindrical portion. The solenoid is characterized by being formed.

  According to a fifth aspect of the present invention, in the invention according to the third or fourth aspect, the front auxiliary magnetic pole has a gap between the cylindrical portion and the cylindrical portion of the fixed magnetic pole. It is a solenoid characterized by being arranged so that it may become larger than the thickness between the 1st field and the 2nd field of a cylindrical part.

  According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, the fixed magnetic pole has a step portion formed in a hollow portion of the cylindrical portion, and the fixed magnetic pole The solenoid further includes an air gap bush provided so as to contact the stepped portion of the cylindrical portion.

  According to a seventh aspect of the present invention, in the invention according to any one of the sixth aspect, the third magnetic pole is obtained by subtracting the thickness of the air gap bush from the first distance. A solenoid characterized by being equal to or approximately equal to the length.

  According to the first aspect of the present invention, at least the first region within the first distance from the distal end portion of the cylindrical portion of the inner peripheral surface is a surface parallel to the central axis of the movable magnetic pole, and is cylindrical. Since the second region within the second distance from the tip of the cylindrical portion is the surface parallel to the central axis of the movable magnetic pole, the thickness between the two is constant. And parallel to the central axis of the movable magnetic pole. And the third region that exceeds the second distance from the distal end portion of the outer peripheral surface of the tubular portion and is within the third distance from the distal end portion of the tubular portion has a thickness of the tubular portion as described above. Since it is formed in an inclined surface that gradually increases toward the base end side of the cylindrical portion, the outer peripheral surface of the cylindrical portion is an inclined surface that is ascending with a flat surface parallel to the central axis of the movable magnetic pole. And the inner peripheral surface is at least parallel to the flat surface. According to the inventor's knowledge, this configuration has an effect of reducing a change in the amount of magnetic flux that contributes to thrust by a portion parallel to the central axis of the movable magnetic pole while the thickness of the portion within the second distance is constant. Therefore, it is possible to reduce the change in the adsorption force, that is, to increase the stability of the thrust, and at the same time, further increase the length of the control stroke region.

  According to the second aspect of the present invention, since the magnetic flux radiated to the space by the auxiliary magnetic pole can be supplemented, the thrust can be increased over the entire stroke, so that it is orthogonal to the attracting direction of the movable magnetic pole for adjusting the thrust or Thrust loss caused by increasing the flow of magnetic flux in a direction close to this can be compensated.

  According to the third aspect of the present invention, since the cylindrical portion of the auxiliary magnetic pole extends toward the tip side of the cylindrical portion of the fixed magnetic pole, the magnetic flux radiated to the space can be supplemented, and the fixed magnetic pole Since the space between the cylindrical portion and the auxiliary magnetic pole can be effectively utilized, it is possible to ensure an increase in thrust and stability without increasing the size of the solenoid.

  According to the fourth aspect of the present invention, the step portion between the auxiliary magnetic pole and the fixed magnetic pole is formed by forming the step portion in the cylindrical portion of the auxiliary magnetic pole so that the thickness of the portion near the cylindrical portion of the fixed magnetic pole is reduced. The flow of the parasitic magnetic flux flowing through can be reduced.

  According to the fifth aspect of the present invention, the gap between the cylindrical portion of the auxiliary magnetic pole and the cylindrical portion of the fixed magnetic pole has a thickness between the first region and the second region of the cylindrical portion of the movable magnetic pole. By making it larger than this, it is possible to reduce the flow of parasitic magnetic flux that flows between the auxiliary magnetic pole and the fixed magnetic pole.

  According to the sixth aspect of the present invention, since the air gap bushing is provided so as to abut on the step portion of the cylindrical portion of the fixed magnetic pole, an excessive amount immediately before the movable magnetic pole is attracted to the fixed magnetic pole becomes unnecessary in the proportional solenoid. Can be prevented. As a result, the return time of the movable magnetic pole to the original position can be shortened, and the return spring can be reduced to reduce the size of the solenoid.

  According to the seventh aspect of the present invention, since the third distance is equal to or substantially equal to the length obtained by subtracting the thickness of the air gap bush from the first distance, the third distance is viewed from the distal end side of the cylindrical portion of the fixed magnetic pole. The end of the inclined surface of the outer peripheral surface that becomes the climbing gradient and the end of the surface parallel to the central axis of the movable magnetic pole on the inner peripheral surface of the cylindrical portion are at the same position on the central axis of the movable magnetic pole. Therefore, since the end of the inclined surface of the outer peripheral surface coincides with the stop position of the movable magnetic pole, the inclined surface of the outer peripheral surface is not excessively formed.

It is sectional drawing of the solenoid which concerns on embodiment of this invention, (a) shows a non-energized state, (b) shows an energized state. It is a figure which shows the solenoid which concerns on embodiment of this invention, (a) is a front view, (b) is a left view. It is sectional drawing which shows the structure of the principal part of the Example and comparative example of this invention, (a) and (b) shows a comparative example, (c) shows the Example of this invention. It is a graph which shows the result of the comparative experiment of the Example and comparative example of this invention. It is sectional drawing which shows the structure of the principal part in another comparative example which performed the magnetic field analysis. It is sectional drawing which shows the structure of the solenoid which concerns on a prior art.

  A solenoid according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a solenoid according to an embodiment of the present invention, where (a) shows a non-energized state and (b) shows an energized state. In FIG. 1, 10 is a solenoid, 20 is a fixed magnetic pole, 21 is a thrust adjusting portion, 22 is an outer peripheral surface, 23 is an inner peripheral surface, 24 is a tip surface, 25 is a cylindrical portion, 26 is an inclined surface, and 27 is a bowl shape. Part, 28 is a through hole, 29 is an air gap bush, 30 is an auxiliary magnetic pole, 31 is a cylindrical part, 32 is a tip surface, 33 is a bowl-shaped part, 34 is a through hole, 35 is a step part, 36 is a case, 37 The crimping part, 38 is a coil, 39 is a bobbin, 40 is a movable magnetic pole, 41 is a shaft, 42 is an end cap, and 43 is a bowl-shaped part. FIG. 2 is a view showing a solenoid according to the embodiment of the present invention, in which (a) is a front view and (b) is a left side view. The reference numerals used in FIG. 2 are the same as those in FIG. In addition, in each drawing including FIG. 1, since a spring, a ring, a sleeve, a lead-out (lead) wire, and a connection terminal are parts that are not related to the present invention, description and explanation are omitted. Further, for the coil 38, description of a fine aspect in which the wire is repeatedly wound is omitted.

  As shown in FIG. 2, the solenoid 10 has an internal structure housed in a substantially cylindrical case 36. In the case 36, the opening on the side from which the shaft 41 protrudes is closed by the flange portion 27 of the fixed magnetic pole 20, and the opening on the opposite side is closed by caulking the end cap 42 with the caulking portion 37. . As shown in FIG. 1, the internal structure of the solenoid 10 is provided with a movable magnetic pole 40 and a shaft 41 as components that move linearly. Further, a fixed magnetic pole 20, an auxiliary magnetic pole 30, and a case 36 are provided as fixed components that actuate and support the components that move linearly by forming a magnetic circuit together with the components that move linearly.

  The solenoid 10 having such a configuration appropriately adjusts the magnitude of the coil current to create a state in which the spring force (not shown) and the thrust of the movable magnetic pole 40 are antagonized. Is used as a so-called proportional solenoid. Note that the size, outer shape, and the like of the case 36 are not limited to those shown in FIG. 2, and can be appropriately changed according to required functions such as waterproofness and oilproofness. Further, the solenoid according to the present invention is not limited to that used as a proportional solenoid, but can be preferably applied to a solenoid such as a tubular solenoid that requires stability of suction force and length of a control stroke region. .

  Next, the components of the solenoid 10 that move directly will be described. The movable magnetic pole 40 of the solenoid 10 is formed in a long and thick cylindrical shape, and a shaft 41 is fitted in a hollow portion formed along the central axis. Further, as will be described later, when the coil 38 is energized, it slides inside the through holes of the fixed magnetic pole 20 and the auxiliary magnetic pole 30 and is attracted to the fixed magnetic pole 20. The attracting force at this time becomes the thrust. Since the air gap bush 29 is inserted inside the cylindrical portion 25 of the fixed magnetic pole 20, the movable magnetic pole 40 does not hit the fixed magnetic pole 20 and come into direct contact therewith.

  The shaft 41 is formed in a round bar shape, and an intermediate portion is fitted into the hollow portion of the movable magnetic pole 40. Further, the tip portion is exposed to the outside through the through hole of the fixed magnetic pole 20. When the coil 38 is not energized, it is urged toward the end cap 42 by the elastic force of a spring (not shown), and the base end is in contact with the end cap 42. Further, when the coil 38 is energized, the coil 38 protrudes greatly from the through hole of the fixed magnetic pole 20.

  Furthermore, the fixed components of the solenoid 10 that actuates and supports the linearly moving components will be described. The fixed magnetic pole 20 includes a bowl-shaped part 27 formed in a disk shape and a cylindrical part 25 formed from the bowl-shaped part 27 toward the end cap 42 side. The bowl-shaped portion 27 is a portion that is fitted into the distal end side of the shaft 41 of the case 36 by press-fitting, and a recess is formed in the center of the outer surface. The cylindrical portion 25 is a portion that has a great influence on the operation of the movable magnetic pole 40, and extends toward the end cap 42 along the central axis of the movable magnetic pole 40 and the shaft 41. Further, the hollow portion of the cylindrical portion 25 is formed with a stepped portion 49 whose diameter is reduced at the tip end side of the shaft 41, and an air gap bush 29 is inserted so as to contact the stepped portion 49. Note that the air gap bush 29 may be omitted depending on the application of the solenoid 10.

  Further, the cylindrical portion 25 has a thrust adjustment portion 21 on the tip side. The thrust adjustment unit 21 is a core part of the present invention, and has a role of stabilizing the thrust of the solenoid 10 and lengthening the control stroke region. The thrust adjustment unit 21 extends in a cylindrical shape toward the end cap 42 along the central axis of the movable magnetic pole 40 and the shaft 41. The outer peripheral surface 22 and the inner peripheral surface 23 of the thrust adjusting unit 21 are cylindrical surfaces parallel to the central axis of the movable magnetic pole 40 and the shaft 41. Therefore, the thickness of the thrust adjusting unit 21 is uniform throughout. A surface closer to the flange-shaped portion 27 than the outer peripheral surface 22 of the thrust adjusting portion 21 is formed as an inclined surface 26 that has an upward gradient toward the flange-shaped portion 27. The inclined surface 26 has a role of mitigating a sudden increase in thrust. In addition, the outer peripheral surface 22 and the inclined surface 26 of the thrust adjusting unit 21 are formed continuously, and no stepped portion is formed between them for the reason described later.

  The auxiliary magnetic pole 30 has a function of increasing thrust by reducing the divergence of magnetic flux to the outside. The auxiliary magnetic pole 30 includes a ring-shaped portion 33 formed in an annular shape and a cylindrical portion 31 formed from the flange-shaped portion 33 toward the fixed magnetic pole 20 side. The hook-shaped portion 33 is fitted into the caulked portion 37 side of the case 36 by press-fitting. Further, since the end cap 42 is fixed by the caulking portion 37, the hook-shaped portion 33 is also fixed so as to be pressed against the fixed magnetic pole 20 side.

  The cylindrical part 31 is one in which the movable magnetic pole 40 slides in the hollow part. Further, it generates a flow of magnetic flux over a wide range of the outer peripheral surface of the movable magnetic pole 40 when the coil 38 is energized, and plays a role of suppressing increase / decrease in thrust generated with a change in the stroke of the movable magnetic pole 40. That is, of the magnetic flux flowing between the movable magnetic pole 40 and the fixed magnetic pole 20, the ratio of the magnetic flux amount contributing to the thrust of the movable magnetic pole 40 to the total magnetic flux amount is likely to change suddenly according to the stroke. Since the cylindrical portion 31 is opposed to the outer peripheral surface of the movable magnetic pole 40 in a wide area, the generation of a magnetic flux that does not contribute to thrust by being diffused in the air is suppressed, and the auxiliary magnetic pole 30, the movable magnetic pole 40, and the fixed magnetic pole 30 are fixed. The amount of magnetic flux flowing through the magnetic pole 20 is increased. As a result, by increasing the amount of magnetic flux flowing through them, there is an effect of relatively reducing the change in the ratio of the magnetic flux amount contributing to the thrust of the movable magnetic pole 40 to the total magnetic flux amount.

  In addition, the cylindrical part 31 may further shorten the length extending toward the fixed magnetic pole 20 side in applications other than the proportional solenoid. Further, all of the portion on the fixed magnetic pole 20 side from the step portion 35 may be omitted. Further, when used as a proportional solenoid, the stability of the thrust is particularly required, so that it is desirable to extend the cylindrical portion 31 toward the thrust adjusting portion 21 for a long time. However, if the distal end surface 32 of the cylindrical portion 31 and the distal end surface 24 of the thrust adjusting portion 21 are too close, a parasitic magnetic circuit that flows through the case 36, the auxiliary magnetic pole 30, and the fixed magnetic pole 20 when the coil 38 is energized. Therefore, it is desirable that the gap between the tip surface 32 and the tip surface 24 be larger than the thickness of the thrust adjustment unit 21.

  The case 36 is formed in a substantially cylindrical shape, and a step portion for press-fitting the flange-like portion 27 of the fixed magnetic pole 20 is formed on the inner peripheral surface on the tip end side of the shaft 41. Further, the end cap 42 side is deformed by caulking, and is in close contact with the peripheral side surfaces of the flange portion 43 of the end cap 42 and the flange portion 33 of the auxiliary magnetic pole 30. The coil 38 is a coil wire wound around a coil bobbin 39, and both ends are not drawn, but are drawn out of the case 36 as lead wires. The coil bobbin 39 is fixed in a state of being sandwiched between the flange portion 27 of the fixed magnetic pole 20 and the flange portion 33 of the auxiliary magnetic pole 30.

  The air gap bush 29 is provided inside the cylindrical portion 25 of the fixed magnetic pole 20 so as to be interposed between the fixed magnetic pole 20 and the movable magnetic pole 40. When the movable magnetic pole 40 is very close to the fixed magnetic pole 20, the thrust of the solenoid 10 becomes very large, but this very large thrust is not necessary for the proportional solenoid. The thickness of the air gap bush 29 is set according to the stroke in which the thrust becomes excessive, and the movable range of the movable magnetic pole 40 is narrowed by providing this. Further, if the movable magnetic pole 40 is not attracted to the fixed magnetic pole 20, there is an advantage that the time for returning to the end cap 42 side by a spring (not shown) can be shortened. Further, there is an advantage that the load of a spring (not shown) can be reduced and the solenoid 10 can be downsized.

  Note that the length along the central axis of the movable magnetic pole 40 and the shaft 41 from the distal end surface 24 of the thrust adjusting portion 21 to the terminal end of the inclined surface 26 on the flange portion 27 side, and the air gap from the distal end surface 24 of the thrust adjusting portion 21. The length along the central axis of the movable magnetic pole 40 and the shaft 41 up to the surface of the bush 29 on the movable magnetic pole 40 side is set to be equal. This is because the inclined surface 26 adjusts the thrust of the movable magnetic pole 40, and it is meaningless to form it beyond the movable range of the movable magnetic pole 40. That is, the surface of the gap bush 29 on the side of the movable magnetic pole 40 serves as a stop position for the movable magnetic pole 40. Therefore, if the inclined surface 26 is formed in accordance with this surface, there is an advantage that unnecessary cutting is not performed. When the gap bush 29 is not provided, the movable magnetic pole 40 and the shaft from the distal end surface 24 of the thrust adjustment portion 21 to the terminal end of the inclined surface 26 on the flange portion 27 side of the inner peripheral surface of the tubular portion 25 are provided. A portion longer than the length along the central axis of 41 may be formed as an inclined surface. Such an inclined surface may be useful for thrust adjustment in a solenoid other than a proportional solenoid.

  The end cap 42 is a lid that closes the proximal end side of the shaft 41. The hook-like portion 43 is fixed to the case 36 by caulking the caulking portion 37 of the case 36. Depending on the application of the solenoid 10, the end cap 42 may be formed of a thick magnetic material so as to be a part of the magnetic circuit, and the auxiliary magnetic pole 30 may be omitted. Furthermore, both the end cap 42 and the auxiliary magnetic pole 30 may be part of the magnetic circuit.

  Further, the operation of the solenoid 10 will be described. When the coil 38 is not energized, as shown in FIG. 1A, the shaft 41 is pressed to the proximal end side by the spring force (not shown), and the proximal end portion contacts the end cap 42. It will be in the state. When the coil 38 is energized, a magnetic circuit is generated in the fixed magnetic pole 20, the case 36, the auxiliary magnetic pole 30, and the movable magnetic pole 40, thereby generating an attractive force to the fixed magnetic pole 20 and sliding on the movable magnetic pole 40. As shown in FIG. 1B, the movable magnetic pole 40 is in contact with the air gap bush 29. In the present invention, by providing the thrust adjusting unit 21 in the fixed magnetic pole 20, fluctuations in thrust when the movable magnetic pole 40 slides are reduced, and as a result, the control stroke is lengthened.

  Next, experimental results of Examples and Comparative Examples of the present invention will be described. FIG. 3 is a cross-sectional view showing the configuration of the main part of the embodiment of the present invention and a comparative example, (a) and (b) are comparative examples, and (c) is an embodiment of the present invention. The reference numerals used in FIG. 3 are the same as those in FIG. In addition, the dimension unit entered in FIG. 3 is mm. FIG. 4 is a graph showing the results of a comparative experiment between an example of the present invention and a comparative example. In FIG. 4, the origin of the x-axis is a stroke when the movable magnetic pole 40 contacts the air gap bush 29, and (a) is 1.6 mm, (b) and (c) are 2 from the fixed magnetic pole, respectively. The distance is 0.0 mm.

  In this experiment, a comparative example in which the inclined surface 26 is formed on the cylindrical portion 25 of the fixed magnetic pole 20 and the cylindrical portion 25 of the fixed magnetic pole 20 according to the present invention, which are generally found in the proportional solenoid according to the prior art. The thrust was measured and compared with the example in which the thrust adjusting portion 21 was provided on the tip side of the. About a comparative example, it is set as the structure shown to Fig.3 (a) and (b). Further, in the embodiment, as shown in FIG. 3C, a thrust adjusting unit 21 is provided, the length of the movable magnetic pole 40 and the shaft 41 in the central axis direction is 0.7 mm, the thickness is 0.3 mm, and the thrust is adjusted. The gap between the tip surface 24 of the part 21 and the tip surface 32 of the cylindrical part 31 was 2.7 mm. The configuration other than the portions described above is as shown in FIG.

  As a result of the above experiment, as shown in FIG. 4, in Example (c) of the present invention, in the range from the stroke 2.0 mm to 13.0 mm when the movable magnetic pole 40 contacts the air gap bush 29, The fluctuation of thrust became 0.1N or less. Therefore, in Example (c) of this invention, it turned out that the range from 2.0 mm to 13.0 mm has sufficient practicality as a control stroke area of a proportional solenoid. On the other hand, in Comparative Examples (a) and (b), the range in which the variation in thrust is 0.1 N or less is 8.0 mm or less, and the control stroke region is considerably larger than that in Example (c) of the present invention. It became narrow. In the case of the embodiment (c) of the present invention, the stroke variation in the intermediate region in the range from 2.0 mm to 13.0 mm is considerably smaller than 0.1 N, and the variation in the intermediate region is 0.1 N. The stability of the thrust was higher than that of the comparative example (b) that was close to.

  FIG. 5 is a cross-sectional view showing a configuration of a main part in another comparative example in which magnetic field analysis is performed. In FIG. 5, 44 is a thin thrust adjusting portion, 45 is a stepped portion, 46 is a beak-like thrust adjusting portion, 47 is a second inclined surface, 48 is an inner peripheral inclined surface, and other symbols are the same as those in FIG. Show.

  The inventor assumes another comparative example having a configuration close to the thrust adjustment unit 21 of the embodiment (c) of the present invention shown in FIG. 4 and performs magnetic field analysis on the configuration of the fixed magnetic pole of the assumed comparative example. Went and evaluated. As shown in FIG. 5A, the fixed magnetic pole as a comparative example is a thin thrust adjusting portion 44 in which the thickness of the thrust adjusting portion is reduced, and a step 45 is formed between the inclined surface 26 and the fixed magnetic pole. . Next, as shown in FIG. 5 (b), the thrust adjusting portion is a beak-like thrust adjusting portion 46 with a beak-like tip. The inclined surface 26 and the second inclined surface 47 of the beak-like thrust adjusting portion 46 are slightly different in inclination angle. Furthermore, as shown in FIG. 5C, the inner peripheral surface of the cylindrical portion 25 An inner peripheral inclined surface 49 is formed on the 23 side. The thrust adjustment portion 21 has the same length and the same thickness as those in FIG. 1, but is slightly closer to the outer peripheral surface side of the cylindrical portion 25 than that in FIG. 1 by forming the inner peripheral inclined surface 49. It is close.

  According to the results analyzed by the inventor, the embodiment of the present invention shown in FIG. 4 is capable of reducing the variation in thrust by any of (a), (b) and (c) of FIG. It was inferior to c). This is presumably due to the fact that the thrust adjusting portion 21 is formed thinner than those shown in FIGS. 5 (a) and 5 (b). Further, in FIG. 5C, the gap between the thrust adjustment unit 48 and the movable magnetic pole 40 is larger than the gap between the thrust adjustment unit 21 and the movable magnetic pole 40, and this gap difference reduces the effect. Presumed to be. In addition, it has been found that the stepped portion 45 or the inner peripheral inclined surface 49 slightly varies depending on the configuration of the movable magnetic pole or the like, but conversely becomes a factor of fluctuation in thrust. Further, when the analysis is performed while sequentially changing the formation range and the formation position of the inner peripheral inclined surface 49, the inclined surface such as the inner peripheral inclined surface 49 is the range in which the thrust adjusting portion 21 and the inclined surface 26 are provided, that is, the cylindrical portion It has been found that if 25 is provided in a range overlapping with the thrust adjusting portion 21 or the inclined surface 26 when viewed from the outer peripheral side, it is likely to cause a thrust fluctuation. Therefore, the inner peripheral surface of the cylindrical portion 25 is a surface parallel to the central axis of the movable magnetic pole 40 and the shaft 41 in a range where the cylindrical portion 25 is overlapped with the thrust adjusting portion 21 or the inclined surface 26 when viewed from the outer peripheral side. It is desirable.

  As described above, the solenoid 10 according to this embodiment is configured such that the coil 38 is energized with respect to the movable magnetic pole 40 by providing the thrust adjusting portion 21 on the distal end side of the cylindrical portion 25 of the fixed magnetic pole 20. It is possible to reduce the change in thrust when sliding is generated by generating an attractive force to the fixed magnetic pole 20. Further, the length of the control stroke region can be extended as compared with the solenoid according to the related art having the same structure. Further, since the thickness of the thrust adjusting portion 21 is uniform throughout, the fixed magnetic pole 20 can be easily formed by cutting or the like. Further, the cylindrical portion 31 of the auxiliary magnetic pole 30 is formed so as to extend long toward the thrust adjusting portion 21, and is opposed to the outer peripheral surface of the movable magnetic pole 40 over a wide area, thereby contributing to the thrust by diffusing in the air. Generation of the magnetic flux not to be transmitted is increased, and the amount of magnetic flux flowing through the auxiliary magnetic pole 30, the movable magnetic pole 40 and the fixed magnetic pole 20 is increased. As a result, when the amount of magnetic flux flowing through these increases, the change in the ratio of the magnetic flux amount contributing to the thrust of the movable magnetic pole 40 to the total magnetic flux amount can be made relatively small.

  The present invention is not limited to the above-described contents. For example, the case has a bottomed cylindrical shape, the case has a substantially square frame, and two coils as a bidirectional solenoid. The auxiliary magnetic pole is provided outside the case, the tip of the movable magnetic pole is formed in a truncated cone shape, and the hollow side of the cylindrical portion of the fixed magnetic pole is aligned with the tip of the movable magnetic pole. It is formed in a trapezoidal shape, and a part of the movable magnetic pole protrudes outside the case without providing a shaft. The shaft is provided integrally with the valve body of the valve. The gap between the movable magnetic pole and the fixed magnetic pole is an oil passage. Various modifications can be made to the configuration used as a part of the invention without departing from the scope described in each claim.

DESCRIPTION OF SYMBOLS 10 Solenoid 20 Fixed magnetic pole 21 Thrust adjustment part 22 Outer peripheral surface 23 Inner peripheral surface 24 Front end surface 25 Cylindrical part 26 Inclined surface 27 Gutter-shaped part 28 Through-hole 29 Air gap bush 30 Auxiliary magnetic pole 31 Cylindrical part 32 Front end surface 33 Gutter-shaped Portion 34 through-hole 35 step portion 36 case 37 caulking portion 38 coil 39 bobbin 40 movable magnetic pole 41 shaft 42 end cap 43 flange-like portion 44 thin thrust adjusting portion 45 step portion 46 beak-like thrust adjusting portion 47 second inclined surface 48 inner circumference Inclined surface 49 Stepped portion 50 Solenoid 51 Fixed yoke 52 Protruding portion 53 Movable yoke 54 Protruding portion 54a Outer peripheral surface 54b Inner peripheral surface 54c End surface 55 Central portion 56 Tip

Claims (6)

A coil, a fixed magnetic pole disposed in the vicinity of the coil and formed with a cylindrical portion, and a movable magnetic pole whose tip side enters the cylindrical portion and is attracted to the fixed magnetic pole when the coil is energized Having a solenoid,
In the fixed magnetic pole, at least a first region of the inner peripheral surface of the cylindrical portion that is within a first distance from the tip of the cylindrical portion is a surface parallel to the central axis of the movable magnetic pole. Formed,
A second region within a second distance from the tip of the cylindrical portion of the outer peripheral surface of the cylindrical portion is formed to be a surface parallel to the central axis of the movable magnetic pole,
A third region of the outer peripheral surface of the tubular portion that exceeds the second distance from the tip portion of the tubular portion and that is within a third distance from the tip portion of the tubular portion. It is formed on an inclined surface such that the thickness of the cylindrical portion gradually increases toward the proximal end side of the cylindrical portion,
It said first distance is rather long than the second distance,
The solenoid according to claim 3, wherein the third distance is equal to or substantially equal to a length obtained by subtracting a thickness of the air gap bush from the first distance .   2. The solenoid according to claim 1, further comprising an auxiliary magnetic pole disposed in the vicinity of the coil and formed with a cylindrical portion into which the movable magnetic pole is slidably inserted.   The solenoid according to claim 2, wherein the cylindrical portion of the auxiliary magnetic pole extends toward the cylindrical portion of the fixed magnetic pole.   4. The solenoid according to claim 3, wherein the auxiliary magnetic pole has a stepped portion formed in the cylindrical portion so that a thickness of a portion of the fixed magnetic pole near the cylindrical portion is reduced.   In the auxiliary magnetic pole, a gap between the cylindrical portion and the cylindrical portion of the fixed magnetic pole is larger than a thickness between the first region and the second region of the cylindrical portion of the fixed magnetic pole. The solenoid according to claim 3 or 4, wherein the solenoid is arranged to be large. The fixed magnetic pole has a stepped portion formed in a hollow portion of the cylindrical portion,
The solenoid according to any one of claims 1 to 5, further comprising an air gap bush provided so as to abut on the step portion of the cylindrical portion of the fixed magnetic pole.

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