Proportional electromagnet and solenoid valve

Abstract

The application discloses a proportional electromagnet and an electromagnetic valve. The technical problem of the existing proportional electromagnet, which is large in size, high in assembly precision and poor in armature position detection precision, is solved. The proportional electromagnet comprises a magnetic shell provided with a cylindrical cavity along a central axis, an iron core relatively fixed in the cylindrical cavity and provided with an armature movable cavity along the central axis, a winding arranged between the magnetic shell and the iron core, an armature movably embedded in the armature movable cavity, a core cap arranged at one end of the iron core and used for closing the armature movable cavity, and a magnetic sensor embedded in the core cap and used for detecting the position of the armature. The thickness direction of the magnetic sensor is the same as the movement direction of the armature. The proportional electromagnet disclosed by the application is small in size, wide in application range, high in armature action position control precision, simple in assembly, high in yield and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electromagnetic control, and in particular to a proportional electromagnet and a solenoid valve. BACKGROUND

[0002] An electromagnet is a device capable of generating a magnetic field, which is composed of some coils wound around the core. When current flows through the coil, a magnetic field is generated, which in turn forms magnetic lines of force around the core, attracting or repelling ferromagnetic materials, while the ferromagnetic material is generally a armature embedded in the core. Thus, the armature is subjected to the action of the magnetic lines of force and moves accordingly to achieve the effect of operating and pulling mechanical devices. Among them, the core is generally made of high permeability and easy magnetization materials, such as soft iron, electrical steel, etc.; the coil is wound by insulated wire, usually copper wire or aluminum wire. The proportional electromagnet is a kind of electromagnet, which can make the mechanical quantity (force or torque and displacement) generated by it proportional to the size of the input signal (current).

[0003] The proportional electromagnet cooperates with the hydraulic valve to realize remote control of the valves of various hydraulic and pneumatic systems. When the coil winding of the electromagnet passes through the current, the electromagnetic attraction overcomes the spring resistance of the reset spring inside the solenoid valve, and the push rod of the valve body moves, so as to realize the opening of the valve. After the coil winding is powered off, the valve body push rod resets under the action of the reset spring, and the valve is closed. The proportional electromagnet can realize the purpose of continuous control of the pressure, direction and flow of the hydraulic system by controlling the position of the hydraulic valve spool. However, with the increasing requirements of the hydraulic system for control accuracy and reliability, there is a need to accurately detect the moving position of the armature, and then determine whether the armature is moved to the right position through the armature position detection.

[0004] The existing proportional electromagnet armature position detection method known to the inventor is to realize the armature position detection by setting the LVDT linear position sensor. However, in the process of implementing the technical scheme of the present application, the inventor found that when using the LVDT linear displacement sensor to detect the position of the armature, the armature needs to be lengthened in the axial direction of the armature so that the armature is within the detection range of the LVDT linear displacement sensor, which will increase the axial length and volume of the proportional electromagnet. In addition, when using the LVDT linear position sensor to detect the position of the armature, the assembly precision requirement is high, and the detection accuracy is limited, which has a large detection error.

[0005] The information disclosed in this BACKGROUND section is only for the purpose of enriching the understanding of the background of the present disclosure and should not be regarded as acknowledging or implying in any form that this information constitutes prior art known to those skilled in the art. SUMMARY

[0006] In view of at least one of the above technical problems, the present disclosure provides a proportional electromagnet and a solenoid valve, aiming to solve the technical problems of large volume, high assembly precision requirement and poor armature position detection precision of the existing proportional electromagnet.

[0007] According to one aspect of the present disclosure, a proportional electromagnet is provided, which comprises a magnetic shell provided with a cylindrical cavity along a central axis, an iron core oppositely fixed in the cylindrical cavity and provided with an armature movable cavity along the central axis, a winding provided between the magnetic shell and the iron core, an armature movably embedded in the armature movable cavity, a core cap provided at one end of the iron core for closing the armature movable cavity, and a magnetic sensor embedded in the core cap for detecting the position of the armature; the thickness direction of the magnetic sensor is in the same direction as the movement direction of the armature.

[0008] In some embodiments of the present disclosure, the magnetic sensor is arranged on a circuit board.

[0009] In some embodiments of the present disclosure, the circuit board is a ring-shaped structure, the magnetic sensor is a TMR sensor, and at least one magnetic sensor is electrically connected to the ring-shaped circuit board.

[0010] In some embodiments of the present disclosure, two magnetic sensors are correspondingly electrically connected to the ring-shaped circuit board, and the two magnetic sensors are symmetrically arranged on both sides of the ring-shaped circuit board with respect to the center of the ring-shaped circuit board.

[0011] In some embodiments of the present disclosure, the magnetic sensor comprises four terminals, and a magnetoresistance effect element with a resistance varying with an external magnetic field is connected in series between the corresponding adjacent terminals; the circuit board is electrically connected to a signal output lead wire corresponding to the terminals.

[0012] In some embodiments of the present disclosure, the magnetic sensor is a Hall sensor.

[0013] In some embodiments of the present disclosure, a push rod hole for movably embedding a manual push rod is axially provided at the center of the core cap.

[0014] In some embodiments of the present disclosure, the radius of the armature is R, the distance between the magnetic sensor and the central axis of the armature is ΔX, the maximum distance between the magnetic sensor and the end surface of the armature is ΔZ, and the stroke of the armature is L, then ΔX / R≤0.75, ΔX≥2, ΔZ>L, and ΔZ<2R+L.

[0015] In some embodiments of the present disclosure, the iron core comprises a fixed iron core body, a guide sleeve fixed to one end of the fixed iron core body for forming the movable cavity of the armature, and a magnetic shielding sheet arranged at the end face of the fixed iron core body for contacting the armature; the fixed iron core body and the guide sleeve are magnetic material pieces; and the magnetic shielding sleeve and the magnetic shielding sheet are non-magnetic material pieces.

[0016] According to another aspect of the present disclosure, there is provided an electromagnetic valve comprising the proportional electromagnet described above.

[0017] The one or more technical solutions provided in the embodiments of the present application have at least any of the following technical effects or advantages:

[0018] The magnetic sensor embedded in the core cap can accurately detect the position of the armature of the proportional electromagnet, thereby avoiding the problem of increasing the volume of the proportional electromagnet caused by the extension along the axial direction of the armature in the prior art, and realizing the miniaturization of the proportional electromagnet. Based on the boundary conditions identified from long-term practical research experience, the relative installation position of the magnetic sensor in the core cap is reasonably limited, which ensures a wide signal output range of the magnetic sensor and effectively improves the detection accuracy and reliability of the proportional electromagnet for the position of the armature. In addition, the thickness direction of the magnetic sensor is kept consistent with the movement direction of the armature, which can accurately detect the position of the armature while avoiding the adverse effects of installation errors on the measurement accuracy, reducing the assembly precision and improving the yield. Furthermore, the selection complexity of the magnetic sensor can be reduced, and additional magnetic field settings can be avoided, thereby reducing the production cost. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 FIG. 1 is a structural schematic diagram of a proportional electromagnet in an embodiment of the present application.

[0020] Figure 2 FIG. 4 is a partial structural schematic diagram of a magnetic sensor in an embodiment of the present application.

[0021] Figure 3 FIG. 6 is a partial structural schematic diagram of a magnetic sensor in another embodiment of the present application.

[0022] Figure 4 FIG. 8 is a test curve diagram of the magnetic field strength of the proportional electromagnet when ΔX=4mm in an embodiment of the present application.

[0023] Figure 5 FIG. 10 is a test curve diagram of the magnetic field strength of the proportional electromagnet when ΔX=8mm in an embodiment of the present application.

[0024] Figure 6 FIG. 12 is a test curve diagram of the sensor signal output range under different values of ΔX and ΔZ in an embodiment of the present application.

[0025] In the above figures, 1 is a magnetic shell, 21 is a fixed iron core body, 22 is a magnetic isolation sleeve, 23 is a guide sleeve, 3 is a winding, 31 is a skeleton, 4 is an armature, 5 is a core cap, 6 is a magnetic sensor, 61 is a circuit board, and 7 is a manual push rod. DETAILED DESCRIPTION

[0026] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inner", "outer", "vertical", "horizontal", "clockwise", "counterclockwise" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. The present application involves "connection" and "coupling", unless otherwise specified, which includes direct and indirect connection (coupling).

[0027] In order to better understand the technical solutions of the present application, the above technical solutions will be described in detail below in combination with the drawings and specific embodiments.

[0028] To solve the technical problems of poor detection accuracy, high assembly precision requirement of the sensor on the proportional electromagnet, and increase in the volume of the proportional electromagnet when the LVDT linear position sensor is used to detect the position of the armature of the proportional electromagnet in the prior art, the present example discloses a proportional electromagnet, as shown in Figure 1 which comprises a magnetic shell 1. In the present embodiment, the magnetic shell 1 is a soft magnetic material piece with a certain wall thickness, and the outer edge contour is columnar. A columnar cavity is formed along the central axis, i.e., the magnetic shell 1 as a whole has a columnar cylindrical shell structure. An iron core is fixedly embedded in the columnar cavity of the magnetic shell 1. The iron core and the magnetic shell are provided with a winding 3 therebetween. For details, see Figure 1 In the present example, the winding 3 is wound with metal wires such as copper wires. The winding 2 is enclosed outside the iron core by the magnetic shell 1. The winding 3 is provided with two winding terminals and extends from the magnetic shell 1 for connecting the power supply, so as to realize the connection between the winding 3 and the power supply. When the winding 3 is connected to the power supply, the winding 3 is energized and has current flowing therethrough, so as to generate a magnetic field at the winding 3. Since the magnetic shell 1 is a magnetic material piece, it can constrain the magnetic field at the winding 3, reduce magnetic leakage, and avoid the diffusion of the magnetic field outward as much as possible. In the present embodiment, considering that the winding 3 is wound with thin and soft metal wires, in order to avoid deformation of the winding due to external force interference after winding, see Figure 1 In the present example, the winding 3 is wound on the skeleton 31.

[0029] In the present example, the inside of the iron core is movably embedded with an armature along the central axis of the iron core, as shown in Figure 1In this example, the iron core includes a fixed iron core body 21, a magnetic shielding sleeve 22, a guide sleeve 23, and a magnetic shielding sheet ( Figure 1 (Not shown in the image). Specifically, the fixed core body 21 is fixed to one side of the cylindrical cavity of the magnetic housing 1. The end of the fixed core body 21 located inside the cylindrical cavity of the magnetic housing 1 is coaxially connected to the guide sleeve 23 through the magnetic isolation sleeve 22. The outer diameter of the guide sleeve 23 matches the outer diameter of the fixed core body 21. The guide sleeve 23 forms an armature movable cavity inside the core, which is used to movably embed the armature 4 along the core axis within the armature movable cavity. The inner diameter of the armature movable cavity matches the outer diameter of the armature 4, ensuring that the armature 4 moves smoothly within the armature movable cavity while preventing the armature from deviating from the movement axis during movement. At the same time, it ensures that the length of the armature movable cavity is greater than the designed movement length of the armature. Therefore, the fixed core body 21 can concentrate the magnetic field to increase the magnetic flux and magnetic field strength. When the winding 3 is energized and generates a magnetic field, the armature 4 is correspondingly magnetized, thereby generating an electromagnetic attraction between it and the fixed core body 21, causing the armature to move and realizing the action of the proportional electromagnet. Furthermore, by adjusting the magnitude of the current flowing through the winding 3, the magnetic field strength is adjusted, thereby adjusting the electromagnetic force on the armature 4 and achieving proportional position control of the armature. In this embodiment, a magnetic shielding sheet is provided at the end face of the fixed core body 21 that contacts the armature 4, thereby avoiding the problem of excessive electromagnetic force caused by direct contact between the armature 4 and the fixed core body 21. Among them, the fixed core body 21 and the guide sleeve 23 are both magnetic components, while the magnetic shielding sleeve 22 and the magnetic shielding sheet are both non-magnetic components.

[0030] See Figure 1 To prevent the armature 4 from falling out of the armature cavity, a core cap 5 is provided at the end of the iron core to seal the armature cavity. The core cap 5 contains a magnetic sensor 6 for detecting the position of the armature 4. In this embodiment, a TMR sensor is specifically selected. The thickness direction of the magnetic sensor 6 is the same as the movement direction of the armature 4, which minimizes the variation in sensor signal output caused by assembly position errors, effectively reducing assembly difficulty and improving yield. To facilitate the installation and signal output of the magnetic sensor, at least one magnetic sensor is installed on the PCB circuit board. Specifically, in this embodiment, see [link to relevant documentation]. Figure 2, the circuit board 61 is a ring structure, and two magnetic sensors 6 are symmetrically arranged on both sides of the ring-shaped circuit board 61 with respect to the center of the circuit board 61. Correspondingly, an annular groove matching the profile of the ring-shaped circuit board of the magnetic sensor is formed at the end side of the core cap 5, for assembling and embedding the magnetic sensor and the circuit board. In this example, the thickness direction of the magnetic sensor is taken as the Z direction, which is perpendicular to the circuit board. The magnetic sensor is arranged in the same direction as the movement direction of the armature, so that the magnetic sensor can detect the magnetic field in the Z direction. In this example, the magnetic sensors 6 are symmetrically arranged on both sides of the circuit board, which can effectively eliminate the measurement error caused by the assembly deviation of the magnetic sensor in the X direction or the Y direction when the magnetic sensor is assembled into the groove of the core cap 5. In other embodiments, see Figure 3 , the circuit board 61 is a disc structure, and one magnetic sensor 6 is electrically connected to the surface of the circuit board 61. A cylindrical groove with a certain depth is formed in the core cap 5 along the movement direction of the armature, for placing and assembling the magnetic sensor 6. The thickness direction of the magnetic sensor 6 is in the same direction as the movement direction of the armature, so as to realize the detection of the magnetic field in the Z direction. In other embodiments, the magnetic sensor is a Hall sensor.

[0031] In this embodiment, the magnetic sensor 6 includes four wiring terminals, each corresponding to four pins on the periphery of the magnetic sensor, and a magnetoresistance effect element is connected in series between adjacent wiring terminals. The resistance of the magnetoresistance effect element can change with the change of the external magnetic field. In this embodiment, the thickness direction of the magnetic sensor is in the same direction as the movement direction of the armature, so that the resistance of each magnetoresistance effect element in the magnetic sensor changes with the change of the magnetic field in the movement direction of the armature. In addition, the circuit board is also provided with output wires electrically connected to each wiring terminal. Specifically, the magnetoresistance effect element includes a free layer, an intermediate layer and a fixed layer. The magnetization direction of the fixed layer does not change with the external magnetic field, while the magnetization direction of the free layer changes with the external magnetic field. When the position of the armature changes, the magnetic field on the periphery of the magnetic sensor changes, which causes the angle between the magnetization directions of the fixed layer and the free layer to change, and the resistance of the magnetoresistance effect element also changes with the change of the angle. Thus, the change of the sensor output caused by the change of the resistance of the corresponding magnetoresistance effect element is used to determine the change and specific position of the armature.

[0032] In addition, see Figure 1 In order to facilitate manual control of the armature when the electromagnet is powered off, a push rod hole is formed along the central axis of the core cap 5 in this embodiment, and a manual push rod 7 is movably embedded in the push rod hole. Thus, the end of the manual push rod 7 is in contact with the armature, so as to push the armature to move. In addition, in this embodiment, see Figure 1Let the radius of armature 4 be R, the distance of magnetic sensor 6 from the central axis of armature be ΔX, the maximum distance of magnetic sensor 6 from the end face of armature be ΔZ, and the stroke of armature 4 be L. Based on long-term practical research, the inventors found that when ΔX / R≤0.75, the strength of the signal output can be ensured, and ΔX≥2 can ensure that the push rod has a certain installation space and make ΔZ>L to avoid collision between armature and sensor. In addition, ΔZ<2R+L is set to limit the overall length of proportional electromagnet to ensure the miniaturization of electromagnet.

[0033] In this embodiment, the magnetic field strength of the electromagnet was verified by experiments at values ​​of ΔX=4mm and ΔZ=8.51+4mm and ΔX=8mm and ΔZ=8.51+4mm, respectively. The results are shown in [reference needed]. Figure 4 and Figure 5 Where the horizontal axis Stroke represents the distance between the armature and the fixed iron core body, in mm. Figure 4 and Figure 5 It can be seen that with the movement of the armature, the axial magnetic field component of the electromagnet, i.e., the magnetic field component Bz along the direction of armature movement, changes significantly. A magnetic sensor with its thickness in the same direction as the armature's axial movement can effectively detect the magnetic field component Bz. Furthermore, when ΔX changes from 4mm to 8mm, the change in the magnetic field component Bz is very small, reflecting that the technical solution of this application can avoid the adverse effects of sensor installation errors on the sensor's measurement accuracy. In addition, this example also includes verification tests on the sensor signal output range for different combinations of ΔX and ΔZ values; the results are shown in [link to relevant documentation]. Figure 6 As shown in the figure, when the variations of ΔX and ΔZ are within ±1mm, the changes in the sensor signal output are very small. This indicates that using a magnetic sensor has lower assembly tolerance requirements, which can effectively reduce assembly difficulty, improve yield, and reduce production costs.

[0034] Furthermore, this example also discloses a solenoid valve including the aforementioned proportional electromagnet, which includes a hydraulic valve and the aforementioned proportional electromagnet. The hydraulic valve and the proportional electromagnet are coaxially fixedly connected, and the valve core inside the hydraulic valve is coaxially driven connected to the armature of the proportional electromagnet. Thus, when the winding is energized, the armature can be controlled to move accordingly, thereby driving the valve core of the hydraulic valve to move and realizing different degrees of conduction of the solenoid valve. The position of the armature is accurately detected by the magnetic sensor at the core cap of the proportional electromagnet, thereby determining the position of the valve core of the hydraulic valve and realizing precise control of the solenoid valve.

[0035] Although some preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0036] Obviously, a person skilled in the art can make various modifications and variants to the present application without departing from the spirit and scope of the inventive concept. Thus, if these modifications and variants of the present application fall within the scope of the claims below and their equivalents, the present application is intended to include them.

Claims

1. A proportional electromagnet, characterized in that, The system includes a magnetic housing with a cylindrical cavity along its central axis, an iron core fixed within the cylindrical cavity and having an armature movable cavity along its central axis, a winding wound between the magnetic housing and the iron core, an armature movably embedded in the armature movable cavity, a core cap located at one end of the iron core for closing the armature movable cavity, and a magnetic sensor embedded in the core cap for detecting the position of the armature. The thickness direction of the magnetic sensor is the same as the movement direction of the armature. The magnetic sensor is correspondingly mounted on a ring circuit board, and two magnetic sensors are electrically connected to the ring circuit board. The two magnetic sensors are symmetrically arranged on both sides of the ring circuit board about the center of the ring circuit board. Let the radius of the armature be R, the distance of the magnetic sensor from the central axis of the armature be ΔX, the maximum distance of the magnetic sensor from the end face of the armature be ΔZ, and the stroke of the armature be L. Then, ΔX / R ≤ 0.75, ΔX ≥ 2, ΔZ > L, and ΔZ < 2R + L.

2. The proportional electromagnet according to claim 1, characterized in that, The magnetic sensor is a TMR sensor.

3. The proportional electromagnet according to claim 1, characterized in that, The magnetic sensor includes four terminals, and a magnetoresistive element whose resistance changes with the external magnetic field is connected in series between adjacent terminals; the circuit board is electrically connected to a signal output wire corresponding to the terminals; the resistance of the magnetoresistive element changes with the change of the magnetic field along the direction of armature movement.

4. The proportional electromagnet according to claim 1, characterized in that, The magnetic sensor is a Hall sensor.

5. The proportional electromagnet according to claim 1, characterized in that, The core cap has an axially oriented push rod hole at its center for movably mounting a manual push rod.

6. The proportional electromagnet according to claim 1, characterized in that, The iron core includes a fixed iron core body, a guide sleeve fixed to one end of the fixed iron core body by a magnetic shielding sleeve to form the armature movable cavity, and a magnetic shielding sheet disposed on the end face of the fixed iron core body for contacting the armature; the fixed iron core body and the guide sleeve are magnetic components; the magnetic shielding sleeve and the magnetic shielding sheet are non-magnetic components.

7. A solenoid valve, characterized in that, Includes the proportional electromagnet as described in claim 1.

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