Proportional electromagnet capable of detecting position of armature and electromagnetic valve

Abstract

The invention discloses a proportion electromagnet capable of detecting the position of an armature and an electromagnetic valve, and aims to solve the technical problems that when an existing proportion electromagnet detects the position of the armature, the detection precision is limited, and the size of the proportion electromagnet is increased. The excitation winding is correspondingly arranged in the magnet yoke; the iron core is relatively fixed in the magnet yoke; the armature is coaxially embedded in the magnet yoke and is used for moving along the axial direction of the magnet yoke; the end pipe is coaxially arranged at the corresponding end of the magnet yoke, and the inner edge diameter of the end pipe is matched with the diameter of the armature; the end cap is used for sealing the end tube and limiting the moving range of the armature, and the TMR sensor is fixed to the corresponding position of the outer edge of the end tube and used for detecting the position of the armature. The proportion electromagnet has the advantages of being high in detection precision, low in assembly difficulty, small in structural size and the like.

Description

Technical Field

[0001] The present application relates to the technical field of electromagnets, and in particular to a proportional electromagnet and a solenoid valve capable of detecting an armature position. Background Art

[0002] Proportional electromagnet is a device based on the principle of electromagnetic induction. It controls the change of mechanical thrust generated by changing the input current, thereby achieving precise control of various devices. Proportional electromagnet usually consists of three parts: winding, iron core and power supply. The power supply is used to provide working current to the winding. When the current passes through the winding, a magnetic field is generated. The magnetic field strength of the magnetic field is directly proportional to the magnitude of the current flowing through the winding. The iron core can be used to increase the magnetic field strength and is usually made of soft magnetic material with high magnetic permeability.

[0003] The magnetic force of the proportional electromagnet is proportional to the control signal. By adjusting the input current, the magnetic field strength generated by the winding can be changed, thereby controlling the mechanical force generated by the electromagnet, thereby achieving precise proportional control. Therefore, proportional electromagnets are widely used in the automotive industry, industrial automation, aerospace industry, medical industry and other fields.

[0004] As a key component commonly used in hydraulic control systems, proportional solenoids are often used in conjunction with hydraulic valves to control hydraulic systems. However, as the requirements for functions and safety of hydraulic systems continue to increase, it is necessary to ensure that the armature in the proportional solenoid has a high degree of movement accuracy. Therefore, it is necessary to accurately detect the movement position of the armature to determine whether the armature has moved in place.

[0005] The detection methods for the armature position of the proportional electromagnet known to the inventors include armature position detection based on LVDT linear position sensors and based on Hall sensors. However, in the process of realizing the technical solutions in the embodiments of the present application, the inventors of the present application found that when using the LVDT linear displacement sensor to detect the armature position, it is necessary to lengthen the armature along the axial direction of the armature, which will increase the axial length of the proportional electromagnet, thereby affecting its applicability; and when using the Hall sensor to detect the armature position, it is necessary to install a magnet at the end of the axis of the armature to achieve detection, which will also increase 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, making the assembly of the electromagnet more difficult. In addition, when the LVDT linear position sensor and the Hall sensor are used to detect the armature position, the detection accuracy is limited and there is a large detection error.

[0006] 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

[0007] In view of at least one of the above technical problems, the present disclosure provides a proportional electromagnet and a solenoid valve capable of detecting the position of an armature, so as to improve the detection accuracy of the proportional electromagnet when detecting the position of the armature and to miniaturize the volume of the proportional electromagnet.

[0008] According to one aspect of the present disclosure, there is provided a proportional electromagnet capable of detecting the position of an armature, which includes a hollow cylindrical yoke, an excitation winding correspondingly arranged in the yoke, an iron core relatively fixed in the yoke, an armature coaxially embedded in the yoke for axial movement along the yoke, an end tube coaxially arranged at a corresponding end of the yoke and with an inner edge diameter matching the diameter of the armature, an end cap for closing the end tube and limiting the movable range of the armature, and a TMR sensor fixed at a corresponding position on the outer edge of the end tube for detecting the position of the armature.

[0009] In some embodiments of the present disclosure, the end cap is made of non-magnetic material.

[0010] In some embodiments of the present disclosure, the end cap is made of copper or aluminum.

[0011] In some embodiments of the present disclosure, the TMR sensor is fixed at a corresponding position on the outer edge of the end cap through a support member; the support member is made of non-magnetic material.

[0012] In some embodiments of the present disclosure, assuming that the inner diameter of the magnetic yoke is R, and the vertical distance between the TMR sensor and the end tube surface is ΔZ, then ΔZ <R。

[0013] In some embodiments of the present disclosure, the intersection of the end surface of the yoke corresponding to the end cap side and the central axis of the yoke is assumed to be the origin, and the vertical distance of the TMR sensor from the plane where the origin is located along the axial direction of the yoke is assumed to be ΔY, then ΔY-ΔZ>0.8R.

[0014] In some embodiments of the present disclosure, R≤ΔY≤4R.

[0015] In some embodiments of the present disclosure, the TMR sensor includes a first terminal, a second terminal, a third terminal, and a fourth terminal, and TMR detection elements whose resistance varies with the magnitude of the external magnetic field are respectively connected in series between corresponding adjacent terminals.

[0016] In some embodiments of the present disclosure, the proportional electromagnet further includes a permanent magnet disposed beside the TMR detection element for applying a magnetic field to the TMR detection element.

[0017] According to another aspect of the present disclosure, a solenoid valve is provided, which includes the above-mentioned proportional solenoid.

[0018] 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 fixing the TMR sensor at the corresponding position of the outer edge of the end tube, the position of the armature of the proportional electromagnet can be accurately detected, avoiding the problem of increasing the volume of the proportional electromagnet due to extending the armature axial direction or adding magnets in the prior art, thereby realizing the miniaturization and even micro-miniaturization of the proportional electromagnet, and making it easy to assemble, use and maintain. On the other hand, based on the boundary conditions identified by long-term practical research experience, the relative installation position of the TMR sensor at the outer edge of the end tube is reasonably limited, ensuring a wider signal output range of the TMR sensor, and effectively improving the detection accuracy and reliability of the armature position of the proportional electromagnet. In addition, the end tube and the support are both made of non-magnetic materials, which can effectively reduce their adverse effects on the measurement accuracy of the TMR sensor and improve the measurement reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the cross-sectional structure of a proportional electromagnet capable of detecting the position of an armature in one embodiment of the present application.

[0020] Figure 2 It is a marked schematic diagram of a proportional electromagnet in one embodiment of the present application.

[0021] Figure 3 1 is a graph showing the electromagnetic force of a proportional electromagnet in an embodiment of the present application.

[0022] Figure 4 It is a related curve diagram of the magnetic induction intensity of the proportional electromagnet in one embodiment of the present application.

[0023] Figure 5 1 is a graph showing an output signal of a proportional solenoid TMR sensor in one embodiment of the present application.

[0024] Figure 6 This is a data table of the output range of the proportional solenoid TMR sensor in one embodiment of the present application.

[0025] Figure 7 Schematic diagram of a partial structure of a TMR sensor in one embodiment of the present application.

[0026] In the above figures, 1 is a yoke, 2 is an excitation winding, 21 is a winding skeleton, 3 is an iron core, 31 is a magnetic isolation ring, 32 is a guide tube, 33 is an end tube, 4 is an armature, 5 is an end cap, 6 is a support, 7 is a TMR sensor, 71 is a fixed layer, 72 is an intermediate layer, 73 is a free layer, and 74 is a permanent magnet. DETAILED DESCRIPTION

[0027] In order to better understand the technical solution of the present application, the technical solution of the present application will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0028] 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.

[0029] In order to solve the problem that the existing proportional electromagnet has poor detection accuracy when realizing armature position detection through LVDT linear displacement sensor or Hall sensor, and will cause the volume of proportional electromagnet to increase or the number of parts to increase. This example discloses a proportional electromagnet that can detect the armature position (see Figure 1 ), which includes a yoke 1, an excitation winding 2, an iron core 3 and an armature 4.

[0030] The yoke 1 is a hollow cylindrical structure with a certain wall thickness, and an excitation winding 2 is enclosed in the cylinder wall, wherein the excitation winding 2 is wound by copper wire, and winding ends extending from the cylinder wall of the yoke 1 are left at both ends of the winding for connecting to a power source. When the two winding ends of the excitation winding 2 are connected to a power source, a current passes through the metal wire of the excitation winding 2, which in turn generates an electromagnetic field, generates an electromagnetic force on the armature 4, and thus, the corresponding action of the proportional electromagnet is realized by the electromagnetic force. In this embodiment, the yoke 1 used to enclose the excitation winding 2 is made of a soft magnetic material, and thus the magnetic field generated by the excitation winding 2 is guided and concentrated by the yoke 1 made of a soft magnetic material to avoid the occurrence of magnetic leakage, and at the same time, it serves as a shielding member for the external magnetic field. Considering that the excitation winding 2 is not easy to shape due to the thin and soft metal wire during winding and is easily deformed by external force after winding, in this embodiment, the metal wire of the excitation winding 2 is wound on the winding frame 21. The winding frame 21 can support the excitation winding 2 through its own structural rigidity on the one hand, and prevent the excitation winding 2 from being deformed by external force on the other hand.

[0031] See also Figure 1 The hollow magnetic yoke 1 is relatively fixedly coaxially penetrated with an iron core 3, which is fixedly connected to the magnetic yoke 1, and is used to concentrate the magnetic field generated by the excitation winding 2 inside the excitation winding, increase the magnetic flux, and thus achieve the purpose of enhancing the magnetic field strength. In addition, one end of the iron core 3 is coaxially connected to a guide tube 32 through a magnetic isolation ring 31, wherein the guide tube 32 is a hollow tubular structure, and its inner diameter is consistent with the inner diameter of the magnetic isolation ring 31 and matches the outer diameter of the armature 4, thereby realizing the coaxial installation of the armature 5 in the excitation winding 2 through the guide tube 32.

[0032] In this embodiment, see Figure 1The iron core 3 is a cylindrical structure whose outer edge contour matches the inner edge contour of the hollow cavity of the yoke 1, and the outer edge contour of the conduit 32 is consistent with the outer edge contour of the iron core 3; the iron core 3 is provided with a guide rod through hole along its central axis, and one end of the armature 4 is provided with a guide rod penetrating into the guide rod through hole in the center of the iron core. The guide rod serves as the action end of the proportional electromagnet. When the excitation winding 2 is energized and a magnetic field is generated, the armature 2 is magnetized, thereby generating an electromagnetic attraction between the iron core 3, thereby realizing the movement of the armature 4. In this example, the length of the conduit 32 is greater than the designed movement distance of the armature 4 to ensure the movement space of the armature 4.

[0033] See also Figure 1 The end of the conduit 32 is coaxially fixedly connected with an end tube 33, and the end tube 33 is arranged to protrude from the corresponding end surface of the yoke 1 by a certain length. In this embodiment, the inner diameter of the end tube 33 is consistent with the inner diameter of the conduit 32, thereby avoiding the presence of a boss at the joint between the two and affecting the movement of the armature. In addition, in order to prevent the armature 4 from falling off from the end of the end tube 33, see Figure 1 , an end cap 5 is provided at the end of the end pipe 22. In this embodiment, the end pipe 33 is threadedly connected to the end cap 5, and a sealing ring is embedded between the end cap 5 and the inner wall of the end pipe 33 to achieve a good sealing effect. In some other embodiments, a through hole is provided inside the armature 4 to facilitate the flow of hydraulic oil or lubricating oil during hydraulic control.

[0034] To accurately detect the armature position in the proportional solenoid, refer to Figure 1 In this embodiment, the TMR sensor 7 is fixedly arranged at the outer edge of the end tube 33. The TMR sensor 7 is arranged at the outer edge of the end tube 33, which can greatly facilitate the installation of the TMR sensor 7 and reduce the difficulty of assembly. Specifically, in this embodiment, in order to prevent the end tube 33 from affecting the detection accuracy of the TMR sensor 7, the end tube 33 is made of non-magnetic material. In this embodiment, the end tube 33 is made of copper. In some other embodiments, the end tube is made of aluminum. In addition, see Figure 1 The TMR sensor 7 is fixed to the outer edge of the end tube 33 through the support member 6, wherein the support member 6 is made of non-magnetic material, which can reduce the adverse effect on the measurement accuracy of the TMR sensor 7.

[0035] In the long-term research process, it is found that the change of the position of the TMR sensor 7 at the outer edge of the end tube 33 has a great influence on the measurement accuracy of the TMR sensor. Specifically, in this embodiment (see Figure 2), let the inner diameter of the yoke 1 be R, let the vertical distance between the TMR sensor 7 and the surface of the end tube 33 be ΔZ, let the intersection of the end surface of the yoke 1 corresponding to the end cap 5 side and the central axis of the yoke 1 be the origin, let the vertical distance between the TMR sensor 7 and the plane where the origin is located along the axial direction of the yoke 1 be ΔY; the inventors found in the process of implementing this embodiment that when ΔZ<R、ΔY-ΔZ> When R is 0.8R, the measurement accuracy of the TMR sensor can be effectively guaranteed; in addition, in this example, R≤ΔY≤4R is set to further ensure the reliability of the TMR sensor measurement data.

[0036] In this example, the air gap GAP between the end surface of the armature 4 close to the iron core 3 and the iron core 3 is taken as the independent variable (see Figure 2 ), obtain the relationship curve between the air gap GAP and the electromagnetic force of the proportional solenoid (see also Figure 3 ), wherein in this embodiment, the diameter of the armature 4 is 22 mm. 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 4 and the iron core 3 is 2-5 mm, 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 22 mm as an example for explanation.

[0037] Specifically, in this example, the diameter of the proportional electromagnet armature 4 is 22 mm, and the installation position of the TMR sensor 7 at the end cap 5 satisfies ΔY=20 mm, ΔZ=2 mm. Based on the 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 results are shown in Figure 5 ). Figure 5 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 5 It can be seen that when the air gap GAP changes from 2mm to 5mm, the signal change of the Hall sensor is only 0.1mV, while the signal change of the TMR sensor is 22.4mV. 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.

[0038] 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 TMR 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 resistance value of the TMR detection element can change with the change of the magnitude of the external magnetic field. In this example, the TMR detection elements are connected in series to form a Wheatstone bridge circuit to achieve detection. In some other embodiments, the TMR detection elements are connected in parallel to form a Wheatstone bridge.

[0039] The TMR detection element includes a free layer 73, an intermediate layer 72 and a fixed layer 71 (see Figure 7 ), 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 will change 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 can be seen from the results, in this example, the component in the X direction 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 position of the armature. For this reason, in this embodiment, a permanent magnet 74 is built-in in the +X direction and -X direction of the TMR detection element. The permanent magnet 74 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 change of the magnitude of the magnetic field component in the Y direction, thereby achieving the role of detecting the position of the armature.

[0040] 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 ​​(see the results for details). Figure 6 ), Figure 6 The values ​​corresponding to the different combinations of ΔY and ΔZ are the signal ranges output by the TMR sensor when the armature air gap varies within the range of 2mm to 5mm. It is found from practical experience combined with the data in the figure that when ΔZ<R、R≤ΔY≤4R、ΔY-ΔZ> When the voltage is 0.8R, the output range of the TMR sensor is not less than 10mV, thereby ensuring the strength of the sensor signal and the detection accuracy.

[0041] In addition, this example also discloses a solenoid valve including the above-mentioned proportional solenoid, which includes a hydraulic valve and the above-mentioned proportional solenoid. The hydraulic valve is coaxially fixedly connected to the proportional solenoid, and the valve core in the hydraulic valve is coaxially transmission connected to the armature of the proportional solenoid. Therefore, after the excitation winding is energized, the armature movement can be controlled accordingly, thereby driving the hydraulic valve core to move, thereby achieving different degrees of conduction of the solenoid valve, and the TMR sensor at the end cap of the proportional solenoid accurately detects the armature position, thereby determining the position of the hydraulic valve core and achieving precise control of the solenoid valve.

[0042] Although some relevant preferred embodiments of the present application 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 falling within the scope of the present application.

[0043] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the inventive concept. Thus, if these modifications and variations to the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A proportional electromagnet capable of detecting the position of an armature, characterized in that: It includes a hollow cylindrical yoke, an excitation winding corresponding to the yoke, an iron core relatively fixed in the yoke, an armature coaxially embedded in the yoke for axial movement along the yoke, an end tube coaxially arranged at the corresponding end of the yoke and with an inner edge diameter matching the armature diameter, an end cap for closing the end tube and limiting the movable range of the armature, and a TMR sensor fixed at a corresponding position on the outer edge of the end tube for detecting the position of the armature.

2. The proportional electromagnet according to claim 1, characterized in that: The end cap is made of non-magnetic material.

3. The proportional electromagnet according to claim 2, characterized in that: The end cap is made of copper or aluminum.

4. The proportional electromagnet according to claim 1 or 2, characterized in that: The TMR sensor is fixed at a corresponding position on the outer edge of the end cap through a support member; the support member is made of non-magnetic material.

5. The proportional electromagnet according to claim 1, characterized in that: Assume that the inner diameter of the magnetic yoke is R, and the vertical distance between the TMR sensor and the end tube surface is ΔZ, then ΔZ <R。 6. The proportional electromagnet according to claim 5, characterized in that: Assume that the intersection of the end surface of the yoke corresponding to the end cap side and the central axis of the yoke 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 yoke is ΔY, then ΔY-ΔZ>0.8R.

7. The proportional electromagnet according to claim 6, characterized in that: R≤ΔY≤4R.

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, and TMR detection elements whose resistance value varies with the size of the external magnetic field are respectively connected in series between corresponding adjacent terminals.

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

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

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