Proportional electromagnet with position detection function and electromagnetic valve

Abstract

The invention discloses a proportional electromagnet with a position detection function and an electromagnetic valve. The technical problem that the size of an existing proportional electromagnet is increased when armature position detection is achieved is solved. The magnet exciting coil is located in the magnetic material sleeve and provided with a supporting framework, the fixed iron core coaxially penetrates through the magnetic material sleeve and is relatively fixed in the magnetic material sleeve, and the armature is movably embedded in the magnetic material sleeve and is used for moving in the axial direction of the magnetic material sleeve. The pipe cap is used for limiting the position of the armature; a TMR sensor used for detecting the position of the armature is embedded in the pipe cap. The proportion electromagnet has the advantages of being small in size, high in detection precision and the like, and the electromagnetic valve composed of the proportion electromagnet has the advantages of being high in control precision and reliability and the like.

Description

Technical Field

[0001] The invention relates to the technical field of electromagnets, and in particular to a proportional electromagnet and a solenoid valve with position detection. Background Art

[0002] A proportional solenoid is a type of travel electromagnet that generates an electromagnetic force or displacement proportional to the current. It works on the principle of electromagnetics and is usually composed of three parts: a winding, an iron core, and a power supply. The winding is a coil made of wire wound around an iron core. When current passes through the winding, according to Ampere's law, a magnetic field is generated, and the strength of the magnetic field is proportional to the magnitude of the current. The role of the iron core is to enhance the strength of the magnetic field. It is usually made of soft magnetic materials with high magnetic permeability, which can effectively concentrate and enhance the magnetic field. The power supply (DC power supply or AC power supply, depending on the application requirements) provides current to the winding, thereby generating a magnetic field. The magnetic force of the proportional electromagnet is proportional to the control signal, thereby achieving precise proportional control. By adjusting the size and voltage value of the control signal, the suction size and direction of the proportional electromagnet can be accurately controlled; therefore, proportional electromagnets are widely used in the automotive industry, industrial automation, aerospace industry, medical industry and other fields.

[0003] In addition, the proportional solenoid is also a commonly used key component in hydraulic control systems. It can be used in conjunction with the hydraulic valve to achieve precise control of the hydraulic system. However, with the continuous improvement of the hydraulic system's requirements for functional safety, it is necessary to accurately detect the position of the iron core, i.e., the armature, in the proportional solenoid.

[0004] The methods for detecting the position of the core of a proportional electromagnet known to the inventors include using an LVDT linear position sensor for position detection and using a Hall sensor for position detection. However, in the process of implementing the technical solution in the embodiments of the present application, the inventors of the present application discovered that when using an LVDT linear displacement sensor for armature position detection, the armature needs to be lengthened along the axial direction, which increases the axial length of the proportional electromagnet and affects its installation applicability. In addition, some proportional solenoid valves are limited by their structure and cannot be equipped with an LVDT in the axial direction. When using a Hall sensor for armature position detection, it is necessary to cooperate with a magnet installed at the end of the armature axis to achieve detection, which also increases the axial length of the armature, and the installation of a magnet will also increase the volume of the proportional electromagnet, while increasing the number of accessories and increasing the difficulty of assembly.

[0005] The information disclosed in this background technology section is only used to deepen the understanding of the background technology of the present disclosure, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art known to those skilled in the art. Summary of the invention

[0006] The present disclosure provides a proportional electromagnet and a solenoid valve with position detection, aiming to solve the technical problem that the existing proportional electromagnet will increase the volume of the proportional electromagnet when realizing armature position detection.

[0007] According to one aspect of the present disclosure, there is provided a proportional electromagnet with position detection, which includes a magnetic material sleeve, an excitation coil located in the magnetic material sleeve and provided with a supporting frame, a fixed iron core coaxially arranged and relatively fixed in the magnetic material sleeve, an armature movably embedded in the magnetic material sleeve and used for axial movement along the magnetic material sleeve, and a pipe cap for limiting the position of the armature; a TMR sensor for detecting the position of the armature is embedded in the pipe cap.

[0008] In some embodiments of the present disclosure, a blind hole is opened at the end surface of the tube cap along the axial direction of the magnetic material sleeve, and the TMR sensor is correspondingly embedded in the blind hole.

[0009] In some embodiments of the present disclosure, assuming that the diameter of the armature is R, and the vertical distance between the TMR sensor and the central axis of the magnetic material sleeve is ΔZ, then ΔZ / R<81%.

[0010] In some embodiments of the present disclosure, R-ΔZ≥2 mm.

[0011] In some embodiments of the present disclosure, a through hole for installing a corresponding manual push rod is provided in the center of the tube cap, and ΔZ≥2mm.

[0012] In some embodiments of the present disclosure, the intersection of the end surface of the magnetic material sleeve close to the pipe cap and the central axis of the magnetic material sleeve is assumed to be the origin, and the vertical distance of the TMR sensor along the axial direction of the magnetic material sleeve from the plane where the origin is located is ΔY, then ΔY≥2mm.

[0013] In some embodiments of the present disclosure, ΔY<2R.

[0014] In some embodiments of the present disclosure, the TMR sensor includes a first terminal, a second terminal, a third terminal, and a fourth terminal. The first terminal and the second terminal, the second terminal and the third terminal, the third terminal and the fourth terminal, and the fourth terminal and the first terminal are respectively connected in series with each other to form a magnetoresistance effect detection element whose resistance value changes with the size of the external magnetic field.

[0015] In some embodiments of the present disclosure, the proportional electromagnet further includes a permanent magnet disposed beside the magnetoresistance effect detection element of the TMR sensor for applying a magnetic field to the magnetoresistance effect detection element.

[0016] According to another aspect of the present disclosure, a solenoid valve is provided, which includes the above-mentioned proportional solenoid.

[0017] One or more technical solutions provided in the embodiments of the present application have at least any of the following technical effects or advantages: by detecting the position of the armature of the proportional electromagnet through the TMR sensor embedded in the tube cap, the problem of increased volume of the proportional electromagnet caused by extending the armature axially or adding magnets in the prior art can be avoided, thereby ensuring the miniaturization of the proportional electromagnet; on the other hand, the electromagnet is easy to assemble and is also convenient for maintenance and replacement of accessories during use; further, based on the boundary conditions identified by the inventor's long-term practical research experience, the relative installation position of the TMR sensor is reasonably limited, which ensures a wider signal output range of the TMR sensor and can effectively improve the detection accuracy and reliability of the proportional electromagnet for the armature position. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic cross-sectional structure diagram of a proportional electromagnet with position detection in one embodiment of the present application.

[0019] Figure 2 It is a marked schematic diagram of a proportional electromagnet in one embodiment of the present application.

[0020] Figure 3 1 is a graph showing the electromagnetic force of a proportional electromagnet in an embodiment of the present application.

[0021] Figure 4 It is a related curve diagram of the magnetic induction intensity of the proportional electromagnet in one embodiment of the present application.

[0022] Figure 5 1 is a graph showing an output signal of a proportional solenoid TMR sensor in one embodiment of the present application.

[0023] Figure 6 Schematic diagram of a partial structure of a TMR sensor in one embodiment of the present application.

[0024] Figure 7 This is a data table of the output range of the proportional solenoid TMR sensor in one embodiment of the present application.

[0025] In the above figures, 1 is a magnetic material sleeve, 2 is an excitation coil, 3 is a supporting frame, 41 is a fixed iron core, 42 is a magnetic isolation ring, 5 is an armature, 6 is a pipe cap, 7 is a TMR sensor, 71 is a fixed layer, 72 is an intermediate layer, 73 is a free layer, 8 is a manual push rod, and 9 is a permanent magnet. DETAILED DESCRIPTION

[0026] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "top", "bottom", "inside", "outside", "vertical", "horizontal", "clockwise", "counterclockwise", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0027] The programs involved or relied upon in the following embodiments are all conventional programs or simple programs in the technical field, and those skilled in the art can make conventional selections or adaptive adjustments according to specific application scenarios. In order to better understand the technical solution of this application, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0028] In order to solve the technical problem that the existing proportional electromagnet will increase the volume of the proportional electromagnet or increase the number of parts when the armature position detection is realized by LVDT linear displacement sensor or Hall sensor. This example discloses a proportional electromagnet with position detection, see Figure 1 , which includes a magnetic material sleeve 1, an excitation coil 2 and a support frame 3. The magnetic material sleeve 1 is a cylindrical structure made of soft magnetic material with a certain wall thickness, and the excitation coil 2 is enclosed in the cylinder wall. The excitation coil 2 is wound by a metal wire (such as copper wire, etc.), and the two ends of the coil extend from the cylinder wall of the magnetic material sleeve to connect to the power supply. When the excitation coil 2 is energized, an electromagnetic field will be generated, which will generate an electromagnetic force on the armature 5, and the action of the proportional electromagnet will be realized by this electromagnetic force. In this embodiment, the magnetic material sleeve 1 used to enclose the excitation coil 2 is made of soft magnetic material, thereby guiding and concentrating the magnetic field through the magnetic material sleeve 1, avoiding magnetic leakage, and serving as a shielding member for the external magnetic field. Considering that the excitation coil 2 is not easy to be formed due to the thin and soft metal wire during winding, and is easily deformed by external force after winding, in this embodiment, the excitation coil 2 is wound at the support frame 3. The support frame 3 can support the excitation coil 2 on the one hand, and can prevent the excitation coil 2 from being deformed by external force interference on the other hand.

[0029] To achieve on-demand action of the proportional solenoid, refer to Figure 1, a magnetic core tube is coaxially and relatively fixedly penetrated in the hollow magnetic material sleeve 1 to respond to the magnetic field generated by the excitation coil 2 to realize the action of the electromagnet. Specifically, the magnetic core tube includes a fixed iron core 41, a magnetic isolation ring 42, a guide sleeve 43, an armature 5 and a pipe cap 6. Among them, the fixed iron core 41 is located in the magnetic material sleeve 1 and is relatively fixedly arranged, which can concentrate the magnetic field inside the excitation coil, increase the magnetic flux, and thus achieve the purpose of enhancing the magnetic field strength. One end of the fixed iron core 41 is connected to the guide sleeve 43 through the magnetic isolation ring 42, so that the coaxial installation of the armature 5 in the excitation coil is realized through the guide sleeve 43. In this embodiment, the fixed core 41 is a cylindrical structure whose outer edge contour matches the inner edge contour of the magnetic material sleeve. The guide sleeve 43 is coaxially arranged with the fixed core 41 and the outer edge contour of the guide sleeve 43 is consistent with the outer edge contour of the fixed core 41. The armature 5 is movably embedded in the guide sleeve 43. One end of the armature 5 is provided with a guide rod that passes through the central axis of the fixed core 41. The guide rod serves as the action end of the electromagnet. When the excitation coil 2 is energized to generate a magnetic field, the armature 5 is magnetized accordingly, thereby generating an electromagnetic attraction between the armature 5 and the fixed core, thereby realizing the action of the armature 5. Therefore, in this example, the length of the guide sleeve 43 is greater than the designed movement distance of the armature 5. In addition, in order to prevent the armature 5 from falling off from the end of the guide sleeve 43, see Figure 1 A pipe cap 6 is provided at the end of the guide sleeve 43. In this embodiment, the guide sleeve 43 and the pipe cap 6 are threadedly connected, and a sealing ring is embedded between the pipe cap and the inner wall of the guide sleeve to achieve a good sealing effect. In addition, in some other embodiments, a through hole is provided inside the armature 5 to facilitate the passage of hydraulic oil or lubricating oil when realizing hydraulic control.

[0030] To accurately detect the armature position in the proportional solenoid, refer to Figure 1 In this example, a TMR sensor 7 is embedded in the pipe cap. Specifically, in this embodiment, a blind hole is opened at the end surface of the pipe cap 6 along the axial direction of the magnetic core tube, that is, the movement direction of the armature, and the blind hole is sealed after the TMR sensor is embedded in the blind hole.

[0031] Specifically, in this embodiment, see Figure 2 , let the diameter of the armature be R, let the vertical distance between the TMR sensor and the central axis of the magnetic material sleeve be ΔZ; the inventor found in the process of implementing this embodiment that when ΔZ / R<81%, the signal strength of the TMR sensor can be effectively ensured; further, in this example, considering that the TMR sensor is embedded in the blind hole opened at the pipe cap 6, R-ΔZ≥2mm is defined to ensure the integrity of the blind hole wall, so as to facilitate the installation of the pipe cap and effectively protect the TMR sensor. In addition, in this embodiment, in order to avoid manual resetting of the armature 5 when problems such as power failure of the proportional electromagnet occur, see Figure 1In this example, a through hole is opened at the center of the tube cap 6 along the movement direction of the armature, and a manual push rod 8 is movably embedded in the through hole, so that the proportional electromagnet can be moved by manually pushing the manual push rod 8. In order to ensure that the manual push rod 8 has sufficient and reliable installation space at the tube cap 6, in this embodiment, ΔZ ≥ 2mm, thereby avoiding problems such as the TMR sensor being exposed and contacting and interfering with the manual push rod. In addition, see Figure 2 , the intersection of the end surface of the magnetic material sleeve close to the pipe cap and the central axis of the magnetic material sleeve is set as the origin, the vertical distance of the TMR sensor from the plane where the origin is located along the axial direction of the magnetic material sleeve is set as ΔY, and ΔY≥2mm is ensured, thereby ensuring the structural strength of the pipe cap, thereby preventing the TMR sensor embedded therein from being damaged by external interference. In this embodiment, ΔY<2R, thereby avoiding the proportional solenoid valve from being too long, thereby limiting its use scenario, and further realizing the miniaturization of the proportional solenoid valve.

[0032] See also Figure 2 In this example, the air gap GAP between the end face of the armature 5 close to the fixed iron core 41 and the fixed iron core 41 is taken as the independent variable, and see Figure 3 , obtain the relationship curve between the air gap GAP and the electromagnetic force of the proportional electromagnet, wherein in this embodiment, the diameter of the armature 5 is 22mm. From the relationship curve between the air gap GAP and the electromagnetic force, it can be seen that when the air gap GAP between the armature 5 and the fixed iron core 41 is 2-5mm, the electromagnetic force of the proportional electromagnet is basically constant, which can meet the proportional control requirements of the proportional solenoid valve. Furthermore, this example takes the proportional solenoid valve with an armature diameter of 22mm as an example for explanation.

[0033] Specifically, in this example, the armature diameter of the proportional electromagnet is 22 mm, and the installation position of the TMR sensor at the pipe cap satisfies ΔY=12 mm, ΔZ=6 mm. Based on this proportional electromagnet, an experiment on the relationship between the air gap GAP and the magnetic induction intensity of the electromagnet is conducted. The experimental results are shown in Figure 4 , it can be seen that the magnetic induction intensity mainly appears in the Y and Z direction components, and the X direction component can be ignored. In this example, the TMR sensor is compared with the Hall sensor used in the prior art. The experimental results are shown in Figure 5 . Figure 5 The graph is a graph showing the relationship between the proportional electromagnet air gap GAP and the TMR sensor signal and the Hall sensor signal. The driving voltage of the TMR sensor and the Hall sensor is 1V. The Hall curve in the graph represents the Hall sensor signal, and the MRsensor curve represents the TMR sensor signal. Figure 5It can be seen that when the air gap GAP changes from 2mm to 5mm, the signal change of the Hall sensor is only 0.6mV, while the signal change of the TMR sensor is 40.6mV. That is, under the premise of the same air gap change, the signal change of the TMR sensor is much greater than the signal change of the Hall sensor. The larger signal change can effectively increase the stability of the signal and prevent false detection caused by external disturbances. Therefore, the TMR sensor can achieve high-precision detection of the armature displacement.

[0034] In order to achieve accurate detection output of the TMR sensor, in this embodiment, the TMR sensor includes a first terminal V, a second terminal V1, a third terminal G, and a fourth terminal V2, wherein a magnetoresistance effect detection element is connected in series between the first terminal V and the second terminal V1, the second terminal V1 and the third terminal G, the third terminal G and the fourth terminal V2, and the fourth terminal V2 and the first terminal V, respectively, and the magnetoresistance effect detection element can generate a change in its own resistance value as the magnitude of the external magnetic field changes. In this example, the TMR detection elements are connected in series to form a Wheatstone bridge, and in some other embodiments, the TMR detection elements are connected in parallel to form a Wheatstone bridge.

[0035] Among them, see Figure 6 The TMR detection element includes a free layer 73, an intermediate layer 72, and a fixed layer 71. The magnetization direction of the fixed layer does not change with the change of the external magnetic field, while the magnetization direction of the free layer changes with the change of the external magnetic field. When the angle between the magnetization directions of the free layer and the fixed layer changes, the resistance value of the TMR detection element will change accordingly. In order to change the magnetization direction of the free layer, in this example, the X-direction component and the Y-direction component of the external magnetic field need to change at the same time. Figure 4 As a result, it can be seen that the component in the X direction in this example is basically zero, that is, it is basically unchanged, and only the component in the Y direction changes. If a common TMR detection element is used, the magnetization direction of the free layer is always parallel to the Y direction. In this case, when the magnetic field in the Y direction changes, since the magnetization direction of the free layer is always maintained in the Y direction, that is, the angle between the magnetization directions of the free layer and the fixed layer does not change, the signal output of the TMR will not change, that is, it cannot play the role of detecting the armature position. For this reason, in this embodiment, see Figure 6 Permanent magnets 9 are built into the +X and -X directions of the TMR detection element. The permanent magnets 9 will generate a built-in magnetic field along the X direction in the TMR detection element. The generation of the built-in magnetic field makes the magnetization direction of the free layer not parallel to the Y direction, and the magnetization direction of the free layer will change with the size of the magnetic field component in the Y direction, thereby achieving the purpose of detecting the armature position.

[0036] In this case, a large number of experimental studies were carried out on the TMR signal output range for different combinations of ΔY and ΔZ values. The results are shown in Figure 7The values ​​corresponding to the different combinations of ΔY and ΔZ in the figure are the signal range output by the TMR sensor when the armature air gap varies in the range of 2mm to 5mm. From practical experience and the data in the figure, it is found that when ΔZ / R<81%, the output range of the TMR sensor is not less than 20mV, thereby ensuring the strength of the sensor signal and the detection accuracy.

[0037] In addition, this example also discloses a solenoid valve including the above-mentioned proportional solenoid, which includes the above-mentioned proportional solenoid and a hydraulic valve, the hydraulic valve is coaxially fixedly connected to the magnetic core tube of the proportional solenoid, and the valve core in the hydraulic valve is coaxially transmission connected to the armature of the proportional solenoid, so that after the excitation coil is energized, the armature movement is correspondingly controlled, thereby driving the hydraulic valve core to move, achieving a corresponding degree of conduction, and the TMR sensor at the proportional solenoid tube cap accurately detects the armature position, thereby determining the position of the hydraulic valve core and achieving precise control of the solenoid valve.

[0038] Although some preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0039] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention are diagnosed to fall within the scope of the claims of this application and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A proportional electromagnet with position detection, characterized in that: It includes a magnetic material sleeve, an excitation coil located in the magnetic material sleeve and provided with a supporting frame, a fixed iron core coaxially arranged and relatively fixed in the magnetic material sleeve, an armature movably embedded in the magnetic material sleeve and used for axial movement along the magnetic material sleeve, and a pipe cap for limiting the position of the armature; a TMR sensor for detecting the position of the armature is embedded in the pipe cap.

2. The proportional electromagnet according to claim 1, characterized in that: A blind hole is opened at the end surface of the tube cap along the axial direction of the magnetic material sleeve, and the TMR sensor is correspondingly embedded in the blind hole.

3. The proportional electromagnet according to claim 1, characterized in that The diameter of the armature is R, and the vertical distance between the TMR sensor and the central axis of the magnetic material sleeve is ΔZ, then ΔZ / R<81%.

4. The proportional electromagnet according to claim 3, characterized in that: R-ΔZ≥2mm.

5. The proportional electromagnet according to claim 3 or 4, characterized in that: A through hole for installing a corresponding manual push rod is provided at the center of the pipe cap, and ΔZ≥2mm.

6. The proportional electromagnet according to claim 5, characterized in that: Assume that the intersection of the end surface of the magnetic material sleeve close to the pipe cap and the central axis of the magnetic material sleeve is the origin, and assume that the vertical distance of the TMR sensor from the plane where the origin is located along the axial direction of the magnetic material sleeve is ΔY, then ΔY≥2mm.

7. The proportional electromagnet according to claim 6, characterized in that: ΔY<2R.

8. The proportional electromagnet according to claim 1, characterized in that: The TMR sensor comprises a first terminal, a second terminal, a third terminal and a fourth terminal. The first terminal and the second terminal, the second terminal and the third terminal, the third terminal and the fourth terminal, and the fourth terminal and the first terminal are respectively connected in series with magnetoresistance effect detection elements for generating changes in their own resistance values ​​with the size of the external magnetic field.

9. The proportional electromagnet according to claim 8, characterized in that: It also includes a permanent magnet disposed beside the magnetoresistance effect detection element of the TMR sensor for applying a magnetic field to the magnetoresistance effect detection element.

10. A solenoid valve, characterized in that: The invention comprises the proportional electromagnet as claimed in claim 1.

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