solenoid valve

Abstract

To provide a solenoid valve capable of simplifying a structure and reducing production costs while suppressing increase of hysteresis of valve operation.SOLUTION: A solenoid valve 100 is equipped with an electromagnetic coil 102, a movable core 104 that is moved by excitation of the electromagnetic coil, a rod 108 that is integrally fixed to the movable core, a solenoid guide 118 that guides the movement of the movable core, and a ball bush 116 that slidably supports the rod. The ball bush is disposed on a feeding side of the movable core, and is not disposed on a returning side of the movable core. Between the solenoid guide and a side surface 126 of the movable core opposite to the solenoid guide, a gap is formed. At an end portion 132 on the returning side of the movable core, a thin diameter portion 134 thinner than an outer diameter on the feeding side of the movable core is formed.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a solenoid valve having a movable core that moves when an electromagnetic coil is excited. [Background technology]

[0002] As an example, in a solenoid valve that uses a magnetic coil and a movable iron core, when the magnetic coil is excited, the movable iron core is attracted and becomes movable relative to the main body of the solenoid valve (for example, Patent Document 1). The solenoid valve in Patent Document 1 includes a rod that is fixed integrally to the movable iron core and a pair of ball bushings into which the rod is inserted.

[0003] The rod is fixed integrally to the armature, so when the electromagnetic coil is excited, it moves with the armature. A pair of ball bushings are fixed to the body of the solenoid valve and are arranged to sandwich the armature on either side, supporting the rod so that it can slide. The side of the armature faces the body of the solenoid valve with a gap between them.

[0004] Therefore, when the rod and the movable core move due to excitation of the electromagnetic coil, they slide only against the pair of ball bushings, which reduces the sliding resistance of the solenoid valve of Patent Document 1 and reduces the hysteresis of the valve operation. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-183784 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the solenoid valve of Patent Document 1 uses a pair of ball bushings to support both ends of the rod, which increases the number of parts and production costs. Therefore, simply simplifying the structure by omitting the ball bushings in order to reduce production costs may result in increased hysteresis in the valve operation.

[0007] In view of the above problems, an object of the present invention is to provide a solenoid valve that can suppress an increase in hysteresis in valve operation, while simplifying the structure and reducing production costs. [Means for solving the problem]

[0008] In order to solve the above problems, a typical configuration of an electromagnetic valve according to the present invention is a solenoid valve comprising an electromagnetic coil, a movable core that moves when the electromagnetic coil is excited, a rod fixed integrally to the movable core, a solenoid guide that guides the movement of the movable core, and a ball bush that slidably supports the rod, wherein the ball bush is arranged on the feed side of the movable core but not on the return side of the movable core, a gap is formed between the solenoid guide and the side of the movable core facing the solenoid guide, and a thin-diameter portion that is thinner than the outer diameter of the feed side of the movable core is formed at the end of the return side of the movable core.

[0009] In the above configuration, the ball bushing that slidably supports the rod is located on the feed side of the armature, but not on the return side. Also, a gap is formed between the solenoid guide that guides the movement of the armature and the side of the armature that faces the solenoid guide to allow the armature to move.

[0010] Therefore, in the above configuration, the rod has a cantilever structure supported only by the ball bushing located on the feed side of the movable core. Also, when the electromagnetic coil is excited, the end of the return side of the movable core receives an attractive force (side force) toward the solenoid guide due to the magnetic flux of the magnetic path formed by the electromagnetic coil.

[0011] Because the return end of the armature is not supported by a ball bushing, it tilts toward the solenoid guide when subjected to a side force. Furthermore, if the return end of the armature tilts, the rod fixed integrally to the armature also tilts. If the return end of the armature comes into contact with the solenoid guide, sliding resistance increases when the tilted rod and armature move, resulting in increased hysteresis in valve operation.

[0012] Therefore, in the above configuration, the return end of the movable core is formed with a narrow diameter portion that is smaller than the outer diameter of the feed end, so that even if the return end of the movable core is tilted by a side force, it will not come into contact with the solenoid guide. This reduces the sliding resistance when the rod and movable core move, and suppresses an increase in hysteresis in valve operation.

[0013] That is, in the above configuration, the structure is simplified by using only one ball bush, reducing production costs, while suppressing an increase in hysteresis in valve operation.

[0014] Furthermore, in the above configuration, instead of narrowing the entire side surface of the movable core, including the return and feed sides, only the outer diameter of the return-side end of the movable core is made thinner than the outer diameter of the feed side of the movable core. As a result, only the return-side end of the movable core has a wider gap with the solenoid guide, which prevents a decrease in the attractive force generated by the excitation of the electromagnetic coil. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a solenoid valve that can suppress an increase in hysteresis in valve operation, while simplifying the structure and reducing production costs. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is an overall configuration diagram of a solenoid valve according to an embodiment of the present invention; [Figure 2] FIG. 10 is an overall configuration diagram of a solenoid valve according to a comparative example. [Figure 3] FIG. 10 is a diagram comparing the hysteresis of the solenoid valve of the embodiment and the solenoid valve of the comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0017] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Dimensions, materials, and other specific values ​​shown in the embodiments are merely examples for facilitating understanding of the invention and, unless otherwise specified, do not limit the present invention. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present invention are not shown.

[0018] 1 is an overall configuration diagram of a solenoid valve 100 according to an embodiment of the present invention. The solenoid valve 100 includes an electromagnetic coil 102, a movable iron core 104, a fixed iron core 106, and a rod 108. The movable iron core 104 is formed in a substantially cylindrical shape and is disposed inside the electromagnetic coil 102. The movable iron core 104 is disposed opposite the fixed iron core 106, and receives an attractive force Fa when the electromagnetic coil 102 is excited, causing the movable iron core 104 to move closer to the fixed iron core 106.

[0019] The rod 108 is fixed integrally to the movable iron core 104. Therefore, when the electromagnetic coil 102 is excited, the rod 108 moves together with the movable iron core 104, and the tip 110 of the rod 108 presses against the small diameter shaft 114 of the spool 112, causing the spool 112 to move.

[0020] The solenoid valve 100 further includes a ball bushing 116 and a solenoid guide 118. The ball bushing 116 is disposed inside the fixed core 106 and slidably supports the rod 108. The ball bushing 116 has a substantially cylindrical retainer 120 and a number of balls 122 disposed inside the retainer 120. The ball bushing 116 contacts and supports the rod 108 with these balls 122, and is able to slide the rod 108 with little sliding resistance by utilizing the rolling of the balls 122. A spring 124 is also disposed inside the fixed core 106. The spring 124 is positioned between the ball bushing 116 and the spool 112 and presses against the spool 112.

[0021] The solenoid guide 118 is disposed opposite a side surface 126 of the movable core 104, and guides the movement of the movable core 104. The electromagnetic coil 102 is disposed outside the solenoid guide 118, and is formed by winding a wire around a bobbin 128 made of resin, for example.

[0022] Hereinafter, the side where the movable core 104 moves when the electromagnetic coil 102 is excited will be referred to as the "feed side." When the electromagnetic coil 102 is in a non-excited state, the spool 112 moves toward the movable core 104 by a return spring (not shown), and the side where the movable core 104 is returned will be referred to as the "return side." Furthermore, the fixed core 106 and the solenoid guide 118 will be collectively referred to as the main body 130. When the electromagnetic coil 102 is excited, the movable core 104 moves relative to the main body 130.

[0023] The ball bushing 116 is disposed on the fixed core 106 located on the feed side of the movable core 104 in the main body 130, but is not disposed on the return side of the movable core 104. Furthermore, a gap S for the movable core 104 to move is formed between the solenoid guide 118 in the main body 130 that guides the movement of the movable core 104 and the side surface 126 of the movable core 104 that faces the solenoid guide 118.

[0024] For this reason, the solenoid valve 100 has a cantilever structure in which the rod 108 is supported only by the ball bushing 116 arranged on the fixed core 106. Furthermore, when the electromagnetic coil 102 is excited, the return-side end 132 of the movable core 104 receives an attractive force (side force Fb) directed toward the solenoid guide 118 by the magnetic flux of the magnetic path R formed by the electromagnetic coil 102.

[0025] Because the return-side end 132 of the movable core 104 is not supported by the ball bushing 116, when it receives the side force Fb it tilts toward the solenoid guide 118. Furthermore, when the return-side end 132 of the movable core 104 tilts, the rod 108, which is fixed integrally to the movable core 104, also tilts.

[0026] If the return end 132 of the movable iron core 104 comes into contact with the solenoid guide 118, when the rod 108 and movable iron core 104 move in an inclined state, the sliding resistance increases, resulting in increased hysteresis in the valve operation.

[0027] Therefore, in the solenoid valve 100, a small diameter portion 134 is formed at the return side end 132 of the movable core 104. The small diameter portion 134 is smaller in outer diameter than the feed side portion 136 of the movable core 104. As a result, a step portion 138 is formed in the movable core 104 between the small diameter portion 134 and the feed side portion 136.

[0028] The gap Sa between the small diameter portion 134 of the movable core 104 and the solenoid guide 118 is larger than the gap Sb between the feed-side portion 136 of the movable core and the solenoid guide 118. This gap Sa is appropriately set so that the return-side end 132 of the movable core 104 will not come into contact with the solenoid guide 118 even when it is tilted by receiving a side force Fb. This reduces the sliding resistance when the rod 108 and the movable core 104 move, making it possible to suppress an increase in hysteresis in the valve operation.

[0029] That is, in the solenoid valve 100, the ball bush 116 is reduced to one, simplifying the structure and reducing production costs, while suppressing an increase in hysteresis in valve operation.

[0030] Furthermore, in the solenoid valve 100, rather than narrowing the entire side surface 126 of the movable core 104 that faces the solenoid guide 118, only the outer diameter of the return-side end 132 of the movable core 104 is made thinner than the outer diameter of the feed-side portion 136 of the movable core 104. As a result, of the side surface 126 of the movable core 104, only the return-side end 132 has a wider gap S with the solenoid guide 118. Therefore, in the solenoid valve 100, a decrease in the attractive force Fa generated by the excitation of the electromagnetic coil 102 can be suppressed.

[0031] 2 is an overall configuration diagram of a solenoid valve 100A in a comparative example. The solenoid valve 100A differs from the solenoid valve 100 in that the thin-diameter portion 134 is not formed on the return-side end 132A of the movable core 104A, and the step portion 138 is not present on the side surface 126A of the movable core 104A.

[0032] Figure 3 is a diagram comparing the hysteresis of the solenoid valve 100 of the embodiment and the solenoid valve 100A of the comparative example. Figures 3(a) and 3(b) show the waveforms of the solenoid valve 100 of the embodiment and the solenoid valve 100A of the comparative example, respectively. In the diagram, the horizontal axis represents the stroke of the movable iron cores 104, 104A, and the vertical axis represents the above-mentioned attractive force Fa generated by excitation of the electromagnetic coil 102. In addition, although the units of the stroke and attractive force are omitted in the diagram, the same units are used for comparison in both Figures 3(a) and 3(b).

[0033] As shown in Fig. 2, the movable core 104A does not have a narrow diameter portion 134 formed at the return-side end portion 132A. Therefore, the gap Sc between the return-side end portion 132A and the solenoid guide 118 of the movable core 104A is smaller than the gap Sa shown in Fig. 1. This gap Sc is the same size as the gap Sb between the feed-side portion 136 of the movable core 104A and the solenoid guide 118.

[0034] As a result, in the solenoid valve 100A of the comparative example, when the return-side end 132A of the movable core 104A receives the side force Fb, there is a possibility that it will come into contact with the solenoid guide 118. Therefore, in the solenoid valve 100A, when the rod 108 and movable core 104A move in an inclined state, the sliding resistance increases, and the hysteresis of the valve operation increases, as shown in the waveform of FIG.

[0035] On the other hand, in the solenoid valve 100 of this embodiment, a narrow diameter portion 134 is formed at the return side end 132 of the movable core 104, and a step portion 138 exists on the side surface 126 of the movable core 104. Therefore, in the solenoid valve 100, due to the gap Sa set between the narrow diameter portion 134 of the movable core 104 and the solenoid guide 118, the return side end 132 of the movable core 104 does not come into contact with the solenoid guide 118 even when it is tilted due to the side force Fb.

[0036] Therefore, according to the solenoid valve 100 of this embodiment, when the rod 108 and movable iron core 104 move in a tilted state, the sliding resistance is reduced, and the increase in hysteresis of the valve operation can be suppressed as shown in the waveform of Figure 3(a) compared to the waveform of the solenoid valve 100A of the comparative example in Figure 3(b).

[0037] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such examples. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the claims, and it is understood that such modifications and alterations also fall within the technical scope of the present invention. [Industrial Applicability]

[0038] The present invention can be used as a solenoid valve having a movable iron core that moves when an electromagnetic coil is excited. [Explanation of symbols]

[0039] 100, 100A... solenoid valve, 102... electromagnetic coil, 104, 104A... movable iron core, 106... fixed iron core, 108... rod, 110... tip of rod, 112... spool, 114... small diameter shaft of spool, 116... ball bushing, 118... solenoid guide, 120... retainer, 122... ball, 124... spring, 126, 126A... side of movable iron core, 128... bobbin, 130... main body, 132, 132A... return side end of movable iron core, 134... thin diameter portion, 136... feed side portion of movable iron core, 138... step portion

Claims

[Claim 1] A solenoid valve, An electromagnetic coil; a movable core that moves when the electromagnetic coil is excited; a rod fixed integrally to the movable iron core; a solenoid guide that guides the movement of the movable iron core; a fixed core disposed opposite to the feed side of the movable core; a ball bushing disposed inside the fixed core and slidably supporting the rod; a spring positioned between the ball bushing and the spool and pressing the spool; the ball bushing is disposed on the feed side of the armature and is not disposed on the return side of the armature, a gap is formed between the solenoid guide and a side surface of the movable iron core facing the solenoid guide, A narrow diameter portion having a diameter smaller than that of the feed side of the movable core is formed at the end of the return side of the movable core, the fixed core has an opposing wall through which the rod passes and which is positioned on the movable core side; The solenoid valve is characterized in that the ball bushing abuts against the opposing wall.

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