Position detection sensor

Abstract

To prevent the magnetic switch of a position detection sensor from being affected by a high temperature.SOLUTION: A position detection sensor 50 comprises: a cylindrical member 51 having a magnetic body 52 inserted in an internal space extending from one end to the other end and an edge wall 53 for closing up the one end; a contact member 54 provided on the one end side of the cylindrical member 51 and coming into direct or indirect contact with a float 42 and operating due to the displacement of the float 42; a magnet 57 provided to the contact member 54 and selected between a first state for coming into contact or facing the edge wall 53 by operation of the contact member 54 and adding magnetism to the edge wall 53 and a second state for separating from the edge wall 53 or changing a direction and weakening the magnetism added to the edge wall 53; and a magnetic switch 61 provided to the other end side of the cylindrical member 51, for detecting the magnetism of the magnet 57 reaching the other end side from the magnet 57 in the first state via the magnetic body 52.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a position detection sensor that detects the position of an object. [Background technology]

[0002] A conventional position detection sensor for detecting the position of an object is disclosed, for example, in Japanese Patent No. 6392990 (Patent Document 1). The position detection sensor disclosed in Patent Document 1 is attached to a liquid pressure-feeding device that discharges high-temperature drainage, and detects the position of a float provided inside a casing of the liquid pressure-feeding device.

[0003] Specifically, the position detection sensor described in the patent document comprises a case having a front end and a rear end, a rod-shaped contact member swingably mounted on the front end of the case, an axially shaped movable member mounted in the front end region of the case and moving back and forth within the case in response to the swinging of the contact member, a permanent magnet attached to the rear of the movable member, and a magnetic switch mounted in the rear end region of the case for detecting the magnetism of the permanent magnet.

[0004] The contact member at the front end of the case is disposed directly above the float. When the amount of accumulated drain is small and the float is in the lowered position, the float is separated from the contact member and the contact member is oriented diagonally downward. The movable member and the permanent magnet are disposed on the contact member side, i.e., in the forward position.

[0005] When the amount of accumulated drain increases and the float rises and comes into contact with the contact member, the contact member swings upward, causing the movable member to move backward, bringing the permanent magnet closer to the magnetic switch at the rear end. The magnetic switch detects the magnetism of the permanent magnet and outputs the detection result from the rear end of the case. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6392990 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the inventors have found that there are still some points to be improved in the conventional position detection sensor. That is, the front end of the case is opened, and the movable member is inserted into the opening from the front. Since high-temperature drain flows into the liquid pumping device, the case of the sensor structure is exposed to a high-temperature atmosphere. On the other hand, the magnetic switch is vulnerable to high temperatures, and there is a concern that the magnetic field of the permanent magnet described above may not be detected correctly each time. SUMMARY OF THE PRESENT DISCLOSURE In view of the above-mentioned circumstances, an object of the present invention is to provide a position detection sensor in which a magnetic switch is not affected by high temperatures. [Means for solving the problem]

[0008] For this purpose, the position detection sensor of the present invention comprises a cylindrical member having a magnetic body inserted into an internal space extending from one end to the other end and an end wall closing one end of the magnetic body, a contact member provided on one end of the cylindrical member and in direct or indirect contact with an object and operating in response to the displacement of the object, a magnet provided on the contact member and selectively switched between a first state in which it approaches or faces the end wall and imparts magnetism to the end wall by the operation of the contact member, and a second state in which it moves away from the end wall or changes its position to weaken the magnetism imparted to the end wall, and a magnetic switch provided on the other end of the cylindrical member and detects the magnetism of the magnet reaching the other end side from the magnet in the first state via the magnetic body.

[0009] According to the present invention, the end wall isolates the internal space of the cylindrical member from the high-temperature atmosphere, and the other end of the cylindrical member is not affected by high temperatures. Also, the magnet magnetizes or does not magnetize the magnetic material via the end wall depending on the first and second states. Therefore, the magnetic switch can correctly detect magnetism without being affected by high temperatures.

[0010] The operation of the contact member is not particularly limited. In one aspect of the present invention, the contact member is provided to be swingable and swings with the displacement of the object, and the magnet is placed in different postures in the first state and the second state. According to this aspect, the first state and the second state can be switched by changing the posture of the magnet. Therefore, the positional movement of the magnet can be reduced, which contributes to simplifying the position detection sensor and reducing costs. In another aspect, in the first state and the second state, the magnet may move closer to or farther away from the end wall without changing its posture.

[0011] The shape of the magnetic body is not particularly limited. In a preferred aspect of the present invention, the magnetic body is a round bar. This aspect makes it easier to insert the magnetic body into the internal space of the cylindrical member, and facilitates assembly of the position detection sensor. In another aspect, the magnetic body may be a square bar or another shape.

[0012] The material of the magnetic body is not particularly limited, but it is preferable that the magnetic body is one that can be easily magnetized and demagnetized. In a preferred aspect of the present invention, the magnetic body is soft iron. According to this aspect, when switching between the first state and the second state, no magnetism remains in the magnetic body, and the magnetic switch can correctly detect the positions of the magnet and the contact member.

[0013] The structure and material of the magnet are not particularly limited, but a permanent magnet is preferable. In one aspect of the present invention, the magnet is a samarium-cobalt magnet. According to this aspect, the magnetic force of the magnet does not decrease even when the magnet is exposed to a high-temperature atmosphere. In one aspect of the present invention, the object whose position is detected by the position detection sensor is a float that follows the liquid level of the liquid stored inside the liquid pumping device. Effect of the Invention

[0014] Thus, according to the present invention, the magnetic switch is not affected by high temperatures, and the position of the object can be detected accurately. [Brief description of the drawings]

[0015] [Figure 1]1 is a vertical cross-sectional view showing a liquid pumping device equipped with a position detection sensor according to an embodiment of the present invention; [Diagram 2] 3 is a cross-sectional view showing the position detection sensor (in a first state) of the embodiment. FIG. [Diagram 3] 4 is a cross-sectional view showing the position detection sensor (second state) of the embodiment. FIG. [Figure 4] 4 is a cross-sectional view showing a position detection sensor (first state) according to another embodiment of the present invention. FIG. [Diagram 5] 13 is a cross-sectional view showing a position detection sensor (second state) according to another embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a vertical cross-sectional view showing a liquid pumping device equipped with a position detection sensor according to one embodiment of the present invention. The liquid pumping device 10 is provided in, for example, a steam system, and recovers high-temperature drain (condensate) generated by condensation of steam and pumps it to a boiler or a waste heat utilization device. As shown in FIG. 1, the liquid pumping device 10 includes a casing 20 which is a sealed container, an intake valve 32, an exhaust valve 33, a valve operating mechanism 40, and a position detection sensor 50 according to the claims of the present application.

[0017] The casing 20 has a main body 21 and a lid 22 connected by bolts, and a storage space 23 is formed inside into which drain flows and is stored. The lid 22 is provided with a liquid inlet 24 through which drain flows in, a liquid outlet 25 through which drain is discharged, a gas inlet 26 through which steam (working gas) is introduced, and a gas outlet 27 through which steam (working gas) is discharged. The liquid inlet 24 is provided near the top of the lid 22, and the liquid outlet 25 is provided in the bottom of the lid 22. The gas inlet 26 and the gas outlet 27 are both provided in the top of the lid 22. All of these inlets and outlets, designated by the reference numerals 24 to 27, are connected to the storage space 23.

[0018] The intake valve 32 is provided at the gas inlet port 26, and the exhaust valve 33 is provided at the gas outlet port 27. The intake valve 32 and the exhaust valve 33 open and close the gas inlet port 26 and the gas outlet port 27, respectively. The intake valve 32 introduces steam from the gas inlet port 26 into the storage space 23, and discharges drainage in the storage space 23 from the liquid outlet port 25 by the pressure of the steam. The exhaust valve 33 discharges the steam introduced into the storage space 23 from the gas outlet port 27.

[0019] Valve operating mechanism 40 is provided inside casing 20, and opens and closes intake valve 32 and exhaust valve 33. Valve operating mechanism 40 has a lever 41 extending into storage space 23, and a float 42 attached to the tip of the lever. Float 42 is formed in a spherical shape and disposed in storage space 23. Float 42 follows the drain liquid level (not shown) in storage space 23 and reciprocates between a lower limit position shown by a solid line in Figure 2 and an upper limit position shown by a virtual line, causing lever 41 to swing. Valve operating mechanism 40 opens and closes intake valve 32 and exhaust valve 33 in response to the swing of lever 41.

[0020] The position detection sensor 50 is attached to the upper part of the main body 21, and detects whether the float 42, which is the object of position detection, is at the upper limit position.

[0021] In this embodiment, the intake valve 32 is usually closed, the exhaust valve 33 is open, and the drain gradually flows into the storage space 23 through the liquid inlet 24. During this time, the drain water level in the storage space 23 continues to rise, and the float 42 approaches the upper limit position. As the drain accumulates in the storage space 23, steam is discharged from the gas outlet 27. When the float 42 reaches a predetermined height position, the valve operating mechanism 40 closes the exhaust valve 33 and opens the intake valve 32 to introduce high-pressure steam into the storage space 23. Then, the drain liquid level in the storage space 23 is pushed downward by the pressure of the introduced steam, and the drain is discharged from the liquid outlet 25. That is, the drain in the storage space 23 is pumped. The drain pumped by the liquid pumping device 10 is supplied to a boiler or a waste heat utilization device. When the drain liquid level in the storage space 23 drops due to the discharge of the drain, the float 42 descends.

[0022] When the float 42 approaches the lower limit position, the valve operating mechanism 40 closes the intake valve 32 and opens the exhaust valve 33. Once again, the drain flows in through the liquid inlet 24 and accumulates in the storage space 23, and the above cycle is repeated.

[0023] When the float 42 rises close to the upper limit position and then descends to the lowered position, a magnetic switch (described later) inside the position detection sensor 50 is turned ON / OFF, and the number of cycles described above and the operating status of the liquid pumping device 10 are grasped.

[0024] Next, the position detection sensor 50 will be described in detail. Fig. 2 and Fig. 3 are cross-sectional views showing the position detection sensor 50 of this embodiment, Fig. 2 corresponds to the contact member 54 shown by the solid line in Fig. 1, and Fig. 3 corresponds to the contact member 54 shown by the imaginary line in Fig. 1. The position detection sensor 50 includes a cylindrical member 51, a contact member 54, a magnet 57, and a magnetic switch 61. One end of the cylindrical member 51 is inserted and fixed in the through hole 23h of the main body 21, and the other end extends straight away from the main body 21 to the outside. A magnetic body 52 is disposed in the internal space of the cylindrical member 51. The magnetic body 52 is made of soft iron such as SS400, for example, and extends from one end of the cylindrical member 51 to the other end. The magnetic body 52 is easily magnetized by receiving magnetic flux, and is demagnetized by the disappearance of the magnetic flux.

[0025] One end of the cylindrical member 51 is closed by an end wall 53. Therefore, the internal space of the cylindrical member 51 does not communicate with the storage space 23. The magnetic body 52 is a round bar with one end formed as a flat surface, and this one end surface is abutted against the end wall 53.

[0026] A bracket 55 is provided at one end of the cylindrical member 51. The bracket 55 is a vertical wall that is paired with a vertical wall (not shown) provided on the front side of the paper surface of FIG. 2. A magnet 57 and a rotating member 54b are disposed between the pair of vertical walls. The rotating member 54b is pivotally supported by a pivot 56 that is mounted on the pair of vertical walls. The pivot 56 extends in the horizontal direction. The magnet 57 is attached and fixed at one location in the circumferential direction on the outer circumferential surface of the rotating member 54b, and faces the end wall 53. Specifically, the magnetic pole of the magnet 57 faces the end wall 53.

[0027] The contact member 54 is a rod-shaped body having a base and a tip, and is fixed at the base to the rotating member 54b. The tip side of the contact member 54 extends to the opposite side to the magnet 57 and is capable of swinging about a pivot 56.

[0028] The contact member 54 remains stationary with its tip extending obliquely downward. It should be noted here that the magnet 57 abuts against the top wall 53b that protrudes horizontally from the upper edge of the end wall 53. This restricts the rotation of the rotating member 54b, and the contact member 54 does not swing further downward than the position shown in FIG.

[0029] The magnet 57 is a permanent magnet. Specifically, it is, for example, a samarium-cobalt magnet. The samarium-cobalt magnet is resistant to high temperatures and its magnetic force does not easily decrease over time.

[0030] Returning to the explanation of the magnetic body 52, a notch 59 is formed in the other end of the magnetic body 52 so as to cut out the upper half of a semi-cylinder. The notch 59 is defined by an upward horizontal surface 59f and a vertical surface 59g oriented toward the other end.

[0031] A socket member 58 is connected to the other end of the cylindrical member 51. The socket member 58 has an upwardly opening socket hole 58s and a sideways opening connecting hole 58t. The socket hole 58s and the connecting hole 58t are connected to each other at their hole bottoms.

[0032] The other end of the cylindrical member 51 is inserted into the connecting hole 58t. The other end of the magnetic body 52 protrudes from the other end surface 51c of the cylindrical member 51. Also, the notch 59 in the other end of the magnetic body 52 overlaps with the socket hole 58s. Specifically, the horizontal surface 59f of the notch 59 is flush with the bottom surface of the socket hole, and the vertical surface 59g of the notch 59 is flush with the side surface of the socket hole 58s.

[0033] The lower end of the sensor unit 62 is inserted into the socket hole 58s from above. The magnetic switch 61 is a component of the sensor unit 62, and is disposed on the side of the lower end of the sensor unit 62. When the sensor unit 62 is pushed into the bottom of the socket hole 58s, the lower end of the magnetic switch 61 comes into contact with the horizontal surface 59f of the notch 59. For example, the magnetic switch 61 is a Hall element that uses the Hall effect. Alternatively, for example, the magnetic switch 61 may be a reed switch that includes two ferromagnetic blades in a sealed glass tube.

[0034] The operation of the position detection sensor 50 will be described. When the float 42 is not at the upper limit position as shown by the solid line in FIG. 1, the contact member 54 waits at a lower position due to its own weight. This is called the first state. In the first state, the magnet 57 faces the end wall 53 as shown in FIG. 2. When the magnetic pole of the magnet 57 is oriented toward the end wall 53 in the vicinity of the end wall 53 as in this embodiment, a large amount of magnetic flux extending from the magnetic pole of the magnet 57 passes through the end wall 53 and flows through the magnetic body 52 (i.e., the magnetic body 52 is magnetized) and reaches the magnetic switch 61. In other words, the magnetic switch 61 detects the magnetism of the magnetic body 52. ​​Then, the magnetic switch 61 is turned ON.

[0035] As shown by the imaginary line in FIG. 1, when the float 42 rises to the upper limit position or near the upper limit position, the float 42 pushes up the contact member 54, and the contact member 54 swings upward. This is called the second state. In the second state, the position of the magnet 57 changes as shown in FIG. 3, and it does not face the end wall 53. If the magnetic pole of the magnet 57 is deflected from the end wall 53 or the magnet 57 moves away from the end wall 53 in this way, most of the magnetic flux extending from the magnet 57 does not reach the end wall 53, and only a small amount of magnetic flux reaches the magnetic switch 61 through the magnetic body 52, or the magnetic body 52 is demagnetized. Then, the magnetic switch 61 is turned OFF. That is, in the second state, the magnetism applied from the magnet 57 to the end wall 53 is not detected by the magnetic switch 61.

[0036] The sensor unit 62 measures the pumping cycle of the liquid pumping device 10 by monitoring the ON / OFF switching of the magnetic switch 61, and displays the measurement result or transmits it to the outside.

[0037] According to this embodiment, the cylindrical member 51 has a magnetic body 52 inserted into an internal space extending from one end of the cylindrical member 51 to the other end, and an end wall 53 closing one end of the cylindrical member 51. The contact member 54 and the rotating member 54b are provided on one end side of the cylindrical member 51, and are in direct or indirect contact with the float 42 and move in accordance with the displacement of the float 42. The magnet 57 is provided on the rotating member 54b, and is selectively set to a first state (FIG. 2) in which the magnet approaches or faces the end wall 53 and applies magnetism to the end wall 53, and a second state (FIG. 3) in which the magnet moves away from the end wall 53 or changes direction to weaken the magnetism applied to the end wall 53, depending on the operation of the contact member 54 and the rotating member 54b. The magnetic switch 61 is provided on the other end side of the cylindrical member 51, and detects the magnetism of the magnet 57 reaching the other end from the magnet 57 in the first state via the magnetic body 52. According to this embodiment, the internal space of the cylindrical member 51 is isolated from the high-temperature atmosphere by the end wall 53, and the other end of the cylindrical member 51 can be kept away from the high-temperature main body 21 and the storage space 23. Therefore, the magnetic switch 61 is not affected by high temperatures, and the position of the float 42 can be detected correctly.

[0038] Furthermore, according to this embodiment, the contact member 54 is provided to be swingable and swings in response to the displacement of the float 42, so that the magnet 57 can be placed in different positions between the first state and the second state. This eliminates the need to move the magnet 57 significantly to turn the magnetic switch 61 on and off, which contributes to simplifying the position detection sensor 50 and reducing costs.

[0039] Furthermore, since the magnetic body 52 in this embodiment is a round bar, it becomes easy to insert the magnetic body 52 into the internal space of the cylindrical member 51, and the assembly of the position detection sensor 50 becomes easy.

[0040] Furthermore, since the magnetic body 52 in this embodiment is made of soft iron, when switching between the first state and the second state in which the magnet 57 faces or deflects from the end wall 53, no magnetism remains in the magnetic body 52, and the magnetic switch 61 can correctly detect the position of the contact member 54.

[0041] Furthermore, since the magnet 57 in this embodiment is a samarium-cobalt magnet, even if it is exposed to a high-temperature atmosphere in the storage space 23, a decrease in magnetic flux can be prevented.

[0042] Furthermore, according to this embodiment, a notch 59 is provided at the other end of the magnetic body 52, and at least a part of the magnetic switch 61 is installed in the notch 59. This makes it possible to increase the magnetic flux passing through the magnetic switch 61 when the magnetic body 52 is magnetized, thereby improving the ON sensitivity of the magnetic switch 61.

[0043] Next, another embodiment of the present invention will be described. Figures 4 and 5 are vertical cross-sectional views showing a position detection sensor according to another embodiment, with Figure 4 showing a first state and Figure 5 showing a second state. In the other embodiment, the same components as those in the above-mentioned embodiment are given the same reference numerals and their explanations are omitted, and the different components will be described below. A position detection sensor 50' according to the other embodiment has a basic configuration similar to that of the position detection sensor 50 described above, is attached to the liquid pumping device 10, and detects the position of the float 42. However, the position detection sensor 50' has a magnetic body 72, a rotating member 74, a bracket 75, a socket member 78, and a sensor unit 79 instead of the magnetic body 52, the rotating member 54b, the top wall 53b, the bracket 55, the socket member 58, and the sensor unit 62 described above.

[0044] The magnetic body 72 has a basic configuration common to the magnetic body 52 described above, is disposed in the internal space of the cylindrical member 51, and extends from one end to the other end of the cylindrical member 51. However, one end of the magnetic body 72 is separated from the end wall 53. The other end of the magnetic body 72 is a flat surface and does not protrude from the other end of the cylindrical member 51. In this embodiment, the other end surface of the magnetic body 72 is flush with the other end surface 51c of the cylindrical member 51.

[0045] The rotating member 74 is roller-shaped and is pivoted on a pivot 56 at the center of the rotating member 74. The pivot 56 extends horizontally. The magnet 57 is not attached to the outer circumferential surface of the rotating member 74, but is embedded inside the rotating member 74. Both magnetic poles (N pole and S pole) of the magnet 57 are arranged in the radial direction of the rotating member 74. Therefore, the magnetic flux extending from the magnet 57 is emitted mainly at a right angle to the outer circumferential surface of the rotating member 74.

[0046] The bracket 75 includes a pair of vertical walls that support both ends of the pivot shaft 56, and a stopper 76 that serves as a cross member that is suspended from the vertical walls. The stopper 76 is disposed below the tip portion of the bracket 75. The pair of vertical walls and the stopper 76 may be formed integrally, or may be separate members.

[0047] The base of the rod-shaped contact member 54 is connected to the rotating member 74 above the stopper 76. The weight of the contact member 54 causes the tip of the contact member 54 to drop below the rotating member 74, but the stopper 76 comes into contact with the contact member 54 and supports it from below. Therefore, the contact member 54 is held in an oblique position unless it comes into contact with the float 42 (FIG. 4). The magnet 57 faces the end wall 53 and applies magnetic flux to the end wall 53.

[0048] The socket member 78 has a basic configuration common to the previously described socket member 58, and has an upwardly opening socket hole 58s and a sideways opening connecting hole 58t. However, the bottom surface of the socket hole 58s is located lower than the other end of the magnetic body 72. In other embodiments, the height position of the bottom surface of the socket hole 58s is set to the same height position as the lowermost part of the connecting hole 58t.

[0049] The lower end of the sensor unit 79 is inserted into the socket hole 58s from above. The magnetic switch 61 is a component of the sensor unit 79, and is disposed on the side of the lower end of the sensor unit 79. When the sensor unit 79 is pushed into the bottom of the socket hole 78s, the magnetic switch 61 faces the other end of the magnetic body 72.

[0050] As in the above-described embodiment, the other embodiments also detect when the float 42 rises to a predetermined height. When the float 42 is located below the contact member 54 as shown in Fig. 4, the magnetic pole of the magnet 57 faces the end wall 53. In this case, the magnetic flux emitted from the magnet 57 passes through the end wall 53, flows through the magnetic body 72, and reaches the magnetic switch 61, which is turned on.

[0051] 5, when the float 42 rises and comes into contact with the contact member 54, the contact member 54 is pushed up by the float 42 and swings upward, and the rotating member 74 rotates and takes a downward position so that the magnet 57 does not face the end wall 53. In this case, the magnetic flux emitted from the magnet 57 does not sufficiently reach the end wall 53. As a result, the magnetic flux flowing through the magnetic body 72 becomes small or zero, and the magnetic switch 61 is turned OFF.

[0052] According to another embodiment shown in FIGS. 4 and 5, similarly to the above-described embodiment, the pumping cycle of the liquid pumping device 10 can be measured by detecting whether the float 42 is rising.

[0053] Although the embodiment of the present invention has been described above with reference to the drawings, the present invention is not limited to the illustrated embodiment. Various modifications and variations can be made to the illustrated embodiment within the same scope as the present invention or within an equivalent scope. For example, a part of the configuration may be extracted from one embodiment described above, and another part of the configuration may be extracted from another embodiment described above, and these extracted configurations may be combined. [Industrial Applicability]

[0054] The present invention is advantageously used in metrology. [Explanation of symbols]

[0055] 10 Liquid pumping device, 42 Float, 50, 50' Position detection sensor, 51 Cylindrical member, Magnetic body 52, End wall 53, 54 contact member, 57 magnet, 59 notch, 61 magnetic switch, 62 sensor unit, 76 stopper.

Claims

1. a cylindrical member having an internal space extending from one end to the other end, a magnetic body inserted therein, and an end wall closing the one end; a contact member provided on the one end side of the cylindrical member and in direct or indirect contact with an object and adapted to move in accordance with a displacement of the object; a magnet provided on the contact member, the magnet being selectively moved by the operation of the contact member between a first state in which the contact member approaches or faces the end wall to impart a magnetic field to the end wall, and a second state in which the contact member moves away from the end wall or changes its position to weaken the magnetic field imparted to the end wall; A position detection sensor comprising: a magnetic switch provided on the other end side of the cylindrical member and detecting the magnetic field of the magnet reaching the other end side from the magnet in the first state via the magnetic body.

2. The contact member is provided to be swingable and swings in response to the displacement of the object, The position detection sensor according to claim 1 , wherein the magnet is oriented in different positions in the first state and in the second state.

3. The position detection sensor according to claim 1 , wherein the magnetic body is a round bar.

4. 2. The position detection sensor according to claim 1, wherein the magnetic material is soft iron.

5. 2. The position detection sensor of claim 1, wherein the magnet is a samarium cobalt magnet.

6. 6. The position detection sensor according to claim 1, wherein the object is a float that follows the liquid level of the liquid stored inside the liquid pumping device.

Images