Spring push rod type large-aperture normally-open electromagnetic valve for EHB energy recovery

Abstract

The invention discloses a spring push rod type large-aperture normally-open electromagnetic valve for EHB energy recovery. A coil is arranged outside a magnetism isolating pipe, the interior of the magnetism isolating pipe is in interference fit with a valve body, moving iron is attached to the upper portion of the valve body, a push rod is axially embedded into the valve body in a sliding mode, the top end of the push rod is connected with the moving iron, and the bottom end of the push rod is in a semi-arc shape; the valve seat is fixedly installed on the lower portion of the valve body and is in interference fit sealing, and the conical opening sealing face of the valve seat and the semi-arc shape of the push rod form linear sealing. A large-aperture spring push rod type normally open valve is adopted, the system flow requirement is met, and the response speed and the product performance are improved; the structure of the electromagnetic valve is simplified, a movable iron plug riveting steel ball mode is simplified into a spring push rod mode, the manufacturing process is simplified, the manufacturing cost is reduced, and the production efficiency is improved; through electromagnetic induction calculation and hydraulic simulation, matched breath and electromagnetic valve stroke are designed, so that the electromagnetic valve can be opened by a corresponding opening degree by electrifying a coil at a fixed duty ratio, and the linear control requirement is met.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic control technology, and relates to solenoid valves in automotive electronic hydraulic control systems, specifically to a spring-loaded push rod type large-diameter normally open solenoid valve for EHB energy recovery. Background Technology

[0002] In the energy recovery process of modern automotive electro-hydraulic braking systems (EHB), the solenoid valve, as one of the key actuators, directly affects the functional accuracy and reliability of the vehicle's braking system. With the rapid development of new energy vehicles, higher technical requirements have been placed on electro-hydraulic braking systems, specifically in terms of strong electromagnetic force control, rapid response capability, and excellent pressure regulation and sealing capabilities.

[0003] Currently, mainstream electro-hydraulic braking system solenoid valves on the market mainly adopt direct-acting or pilot-operated structural designs. Direct-acting valves are used for low pressure and small flow, while pilot-operated valves are suitable for high pressure but have a slow response. Existing direct-acting solenoid valves typically consist of key components such as coil assemblies, moving iron cores, valve seats, and sealing assemblies. Magnetic induction refers to the phenomenon where a conductor in a closed circuit moves through a magnetic field, cutting magnetic field lines, thus generating a current in the conductor. This phenomenon of generating current using a magnetic field is called electromagnetic induction, and the generated current is called induced current. The working principle of a solenoid valve is that current flowing through the coil generates magnetic force, which drives the valve core to move, opening the valve and allowing fluid to pass through. When the power is cut off, the magnetic force disappears, the valve core returns to its original position under the action of a spring, the valve closes, and the fluid stops flowing, thereby achieving fluid on / off control. Typical solenoid valves use a conical ball-head sealing principle, which uses an outer nut to press the inner and outer conical surfaces (i.e., the ball head and the conical surface) together for sealing. At the contact point between the precision-machined steel ball and the conical surface of the valve seat, plastic deformation occurs, forming an annular sealing band, thus achieving a seal. In the initial stage, the ball head and the conical surface are in line-to-surface contact. When the installation torque reaches a certain value, the conical surface and the ball head are squeezed and undergo elastoplastic deformation, forming a sealing ring between them. This sealing method requires sacrificing the orifice size to ensure sealing performance, resulting in an inherent throttling effect.

[0004] The existing production process for direct-acting solenoid valves is as follows: 1. Insert the steel ball and plug sequentially from the top of the moving iron; 2. Use a tool to push the plug downwards, controlling the steel ball to protrude 1mm from the moving iron plane; 3. Insert the valve seat from the bottom into the valve body and push it upwards, controlling the steel ball to fit snugly on the valve seat cone surface and protrude 1.8mm; 4. After press-fitting, calculate the solenoid valve's air pressure and stroke based on the press-fitting parameters; 5. Place the moving iron into the magnetic shielding tube; 6. Slide the moving iron and magnetic shielding tube together downwards onto the valve body; 7. Use a tool to press down the magnetic shielding tube flange and push it downwards, making the magnetic shielding tube and valve body interference fit to achieve an external seal. The protruding height of the steel ball needs to be controlled within a tolerance of ±0.05mm, resulting in poor process stability and a product qualification rate of less than 60%.

[0005] Direct-acting solenoid valves are used in the energy recovery function of electro-hydraulic braking systems and also serve as the passage for brake fluid in automobiles. Therefore, the orifice size of the solenoid valve directly affects the braking response speed of the vehicle. The orifice size of the currently used solenoid valves, which is 1.8mm, cannot meet the requirements and causes throttling. At the same time, the orifice size cannot be increased due to the influence of belt structure and size. Therefore, existing solenoid valves have the problems of not being able to meet the flow requirements, having a design stroke that is too small, causing throttling, and requiring wired control of the valve. In addition, the solenoid valve structure is relatively complex, the production cost is high, and the production efficiency is low, which cannot well meet the market demand. Summary of the Invention

[0006] To address the aforementioned problems, the main objective of this invention is to design a spring-loaded push rod type large-diameter normally open solenoid valve for EHB energy recovery, thereby solving the problems of small solenoid valve orifice diameter affecting vehicle braking response speed, throttling issues, low production efficiency, and inability to meet market demands.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A spring-loaded, large-bore normally open solenoid valve for EHB energy recovery includes a magnetic shielding tube, a moving iron, a push rod, a valve body, a valve seat, a steel ball, and an end filter screen. The magnetic shielding tube has a coil on its outside and a valve body inside which it is interference-fitted and fixed. The magnetic shielding tube is connected to a moving iron above the valve body. A push rod is axially slidably embedded inside the valve body. The top of the push rod is connected to the moving iron, and the bottom is set to a semi-circular shape. A return spring for limiting the push rod is sleeved on the outer wall of the push rod. The valve seat is fixedly installed at the lower part of the valve body. The valve seat and the valve body are sealed with an interference fit, and the conical sealing surface of the valve seat and the semi-circular bottom of the push rod form a linear seal. The bottom of the solenoid valve body is interference-fitted with an end filter screen, and a steel ball is embedded between the end filter screen and the valve body.

[0008] As a further description of the present invention, the diameter of the push rod is set to be thicker at the top and thinner at the bottom, the diameter of the inner wall of the valve body is thinner at the top and thicker at the bottom, and an annular cavity is formed between the lower end face of the thick section of the push rod and the upper end face of the thick section of the valve body, the annular cavity being located in the middle of the valve body.

[0009] As a further description of the present invention, the return spring is sleeved on the thin section of the push rod and located in the annular cavity, and is limited by the lower end face of the thick section of the push rod and the upper end face of the thick section of the valve body.

[0010] As a further description of the present invention, a platform is provided at the top of the moving iron, and a pressure balance cavity is formed between the magnetic shielding tube and the top of the moving iron through the provision of the platform.

[0011] As a further description of the present invention, the semi-circular diameter of the bottom of the push rod is 3.1mm±0.05mm, and the cone angle of the valve seat cone is 80°±2°.

[0012] As a further description of the present invention, the push rod is linked with the moving iron, and its stroke is optimized by hydraulic simulation to ensure that the opening between the push rod and the valve seat meets the flow channel with an orifice diameter of 2.2mm.

[0013] As a further description of the present invention, the flange face of the magnetic shielding tube is press-fitted to the valve body by tooling with an interference fit, and the pressing force is 150-200N.

[0014] An assembly method based on the above-mentioned solenoid valve includes the following steps: S1. Valve seat preload: Place the valve seat at the bottom of the valve body and apply a preload of 100N to preload the valve seat into the valve body; S2. Push rod assembly: Install the return spring and push rod in sequence, fine press the valve seat to make the valve seat and valve body seal to an interference fit, and control the air pressure. S3. Moving iron assembly: The moving iron is installed in the magnetic shielding tube, and the moving iron and magnetic shielding tube are pressed in as a whole from the top of the valve body; S4. Magnetic shielding tube seal: Pressure is applied to the flange face of the magnetic shielding tube using a tooling to make the magnetic shielding tube and the valve body fit together and achieve an interference seal; S5. End filter installation: Install an end filter at the bottom of the valve body.

[0015] As a further description of the present invention, in step S2, the interference fit between the valve seat and the valve body after fine pressing is 0.02-0.03 mm.

[0016] Compared with the prior art, the technical advantages of the present invention are as follows: This invention provides a spring-loaded, large-diameter, normally open solenoid valve for EHB energy recovery, comprising a magnetic shielding tube, a moving iron, a push rod, a valve body, a valve seat, a steel ball, and an end filter. A coil is externally mounted on the magnetic shielding tube, and the valve body is internally interference-fitted and fixedly mounted therein. The moving iron is connected to the inside of the magnetic shielding tube above the valve body. The push rod is axially slidably embedded inside the valve body, with its top end connected to the moving iron and its bottom end shaped like a semi-circle. A return spring is fitted onto the outer wall of the push rod. The valve seat is fixedly mounted on the lower part of the valve body, and the valve seat and valve body are interference-fitted for sealing. The conical sealing surface of the valve seat and the semi-circular bottom of the push rod form a linear seal. The bottom of the solenoid valve body is interference-fitted with an end filter screen, and a steel ball is embedded between the end filter screen and the valve body. It adopts a large-diameter spring push rod type normally open valve structure to meet the system flow requirements, improve the system response speed, and improve product performance. The solenoid valve structure is simplified from the moving iron plug riveted steel ball type to the spring push rod type, which simplifies the manufacturing process, reduces manufacturing costs, and improves production efficiency. Through electromagnetic induction calculation and AMEsim software hydraulic simulation, the matching air volume and solenoid valve stroke are designed so that the solenoid valve can open to the corresponding degree by energizing the coil with a fixed duty cycle, thus meeting the linear control requirements. Attached Figure Description

[0017] Figure 1 This is a cross-sectional view of the solenoid valve structure of the present invention; Figure 2 This is a schematic diagram comparing the flow rate and response time of the solenoid valve of the present invention with those of existing solenoid valves. Figure 3 This is a schematic diagram showing the pass rate statistics of the solenoid valve of the present invention and existing solenoid valves.

[0018] In the diagram, 1. Magnetic shielding tube, 2. Moving iron, 21. Platform, 3. Push rod, 4. Valve body, 5. Valve seat, 6. Steel ball, 7. End filter screen, 8. Coil, 9. Return spring, 10. Annular chamber. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings: In one embodiment of the present invention, a spring-loaded push rod type large-bore normally open solenoid valve for EHB energy recovery is disclosed, referenced. Figure 1As shown, the device includes a magnetic shielding tube 1, a moving iron 2, a push rod 3, a valve body 4, a valve seat 5, a steel ball 6, and an end filter screen 7. The magnetic shielding tube 1 has a coil 8 externally mounted, and the valve body 4 is internally fitted and fixedly mounted therein. The moving iron 2 is attached to the upper part of the valve body 4 inside the magnetic shielding tube 1. The push rod 3 is axially slidably embedded inside the valve body 4. The top end of the push rod 3 is connected to the moving iron 2, and the bottom end is semi-arc-shaped. A return spring 9 for limiting the push rod 3 is sleeved on the outer wall of the push rod 3. The valve seat 5 is fixedly installed at the lower part of the valve body 4, and the valve seat 5 and the valve body 4 are sealed with an interference fit. The conical sealing surface of the valve seat 5 and the semi-arc-shaped bottom of the push rod 3 form a linear seal. The end filter screen 7 is internally fitted to the bottom of the valve body 4, and the end filter screen 7 serves a filtering function. The steel ball 6 is embedded between the end filter screen 7 and the valve body 4.

[0020] Specifically, in this embodiment, to achieve the limiting of both ends of the return spring 9, the diameter of the push rod 3 is set to be thicker at the top and thinner at the bottom, and the inner wall diameter of the valve body 4 is also thinner at the top and thicker at the bottom. An annular cavity 10 is formed between the lower end face of the thick section of the push rod 3 and the upper end face of the thick section of the valve body 4, and the annular cavity 10 is located in the middle of the valve body 4. In use, the return spring 9 is sleeved on the thin section of the push rod 3 and located in the annular cavity 10, and is limited by the lower end face of the thick section of the push rod 3 and the upper end face of the thick section of the valve body 4, respectively.

[0021] It should be noted that in this embodiment, a platform 21 is provided at the top of the moving iron 2. The platform diameter is less than 3mm. The platform 21 forms a pressure balance chamber between the top of the magnetic shielding tube 1 and the moving iron 2, so that the pressure at the bottom of the moving iron 2 is balanced with the pressure at the top. The moving iron 2 is slidably connected to the magnetic shielding tube 1. After the current passes through the coil 8 and generates electromagnetic force, the moving iron 2 slides back and forth in the magnetic shielding tube 1 under the action of the spring force of the return spring 9. In addition, the flange face of the magnetic shielding tube 1 is press-fitted to the valve body 4 by tooling, and the pressing force is 150-200N.

[0022] In this embodiment, the design of the solenoid valve prioritizes meeting performance requirements. First, the orifice diameter is checked. After calculating the flow requirements of the entire system, the orifice diameter of the solenoid valve is ultimately determined to be 2.2mm. Specifically, the push rod 3 is linked to the moving iron 2, and its stroke is optimized through hydraulic simulation to ensure that the opening between the push rod 3 and the valve seat 5 meets the flow channel requirements of the 2.2mm orifice diameter, satisfying the system's response speed requirements. Secondly, the ball head design corresponding to the solenoid valve orifice diameter needs to consider the sealing requirements of the valve seat 5's conical opening, and the cone angle and ball head sealing line need to be within a safe range to avoid machining errors. Calculations show that the ball head size is 3.1mm ± 0.05mm, and the cone angle of the valve seat 5's conical opening is 80° ± 2°, meaning the semi-circular diameter of the bottom of the push rod 3 is 3.1mm ± 0.05mm.

[0023] In this embodiment, after designing the conical seal, a solenoid valve simulation model is built using AMEsim software. Parameters such as the valve seat cone angle, push rod ball diameter, and flow coefficient are set to simulate the solenoid valve's operation under the required conditions. Hydraulic environment simulation is performed. By simulating the flow rate at different opening degrees between the solenoid valve push rod and valve seat, the solenoid valve stroke is determined, ensuring that the solenoid valve opening does not affect the flow rate and cause throttling. After determining the solenoid valve's stroke, the air gap is selected. This air gap needs to be simulated using Maxwell software. The 3D model of the solenoid valve, material properties, and coil parameters are imported and solved to obtain the air gap-electromagnetic force curve. Suitable air gap parameters for actual operating conditions are then selected. After determining the solenoid valve's stroke and air gap, the electromagnetic attraction force is calculated using the magnetic circuit segmentation method. Specifically, the solenoid valve structure is divided into several magnetic channels, with each magnetic circuit considered as a branch. An equivalent magnetic circuit model is established using Kirchhoff's laws to calculate the electromagnetic force. Based on the force balance of electromagnetic force, hydraulic pressure, and spring force at the solenoid valve orifice, the spring parameters are designed and determined. This part can be implemented using existing technology.

[0024] In another embodiment of the present invention, an assembly method based on the above-described solenoid valve is also included, comprising the following steps: S1. Valve seat preload: Place the valve seat at the bottom of the valve body and apply a preload of about 100N to preload the valve seat into the valve body; S2. Push rod assembly: Install the return spring and push rod in sequence, and finely press the valve seat again to make the valve seat and valve body seal in an interference fit state, and control the air pressure (push rod stiffness). After fine pressing, the interference fit between the valve seat and valve body is 0.02-0.03mm. S3. Moving iron assembly: The moving iron is installed in the magnetic shielding tube, and the moving iron and magnetic shielding tube are pressed in as a whole from the top of the valve body; S4. Magnetic shielding tube seal: Pressure is applied to the flange face of the magnetic shielding tube by tooling to make the magnetic shielding tube and the valve body interference fit, thereby achieving interference sealing effect; S5. End filter installation: Install an end filter at the bottom of the valve body.

[0025] Through the above embodiments, a spring-push rod type large-diameter normally open solenoid valve for EHB energy recovery is disclosed in this invention. Its working principle is as follows: when an external excitation is applied to the coil, a magnetic field is generated around the coil. The electromagnetic force generated by the coil pushes the moving iron to move downward. The moving iron overcomes the spring force of the return spring and pushes the push rod to move downward. The push rod fits against the conical surface of the valve seat to achieve a sealing effect, and the solenoid valve closes. After the coil is de-energized, the electromagnetic force disappears, and the push rod moves upward under the action of the spring force of the return spring. The push rod pushes the moving iron back to its original position, and the solenoid valve opens.

[0026] The spring-loaded, large-orifice normally open solenoid valve of this invention increases the valve's flow rate and improves the solenoid valve's response time compared to existing valves. Figure 2 and Figure 3 As shown, the flow rate of the solenoid valve was increased from 350ml / s to 562ml / s, and the response time was reduced from 35ms to 26ms. After the improvement, the pass rate of the solenoid valve was increased from 86% to 100%.

[0027] The above content discloses the technical solution of the present invention, which has the following advantages compared with the prior art: 1. This invention adopts a large-diameter spring push rod type normally open valve structure to meet the system flow requirements, improve the system response speed, and improve product performance; 2. This invention simplifies the structure of the solenoid valve, changing it from a moving iron plug with riveted steel ball type to a spring push rod type, simplifying the manufacturing process, reducing manufacturing costs, and improving production efficiency; 3. This invention designs a matching air pressure and solenoid valve stroke through electromagnetic induction calculation and hydraulic simulation using AMEsim software, enabling the solenoid valve to open to the corresponding degree by energizing the coil with a fixed duty cycle, thus meeting the requirements of linear control.

[0028] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the spirit and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A spring-loaded push rod type large-bore normally open solenoid valve for EHB energy recovery, characterized in that: It includes a magnetic shielding tube, moving iron, push rod, valve body, valve seat, steel ball, and end filter screen; The magnetic shielding tube has a coil on its outside and a valve body inside which it is interference-fitted and fixed. The magnetic shielding tube is connected to a moving iron above the valve body. A push rod is axially slidably embedded inside the valve body. The top of the push rod is connected to the moving iron, and the bottom is set to a semi-circular shape. A return spring for limiting the push rod is sleeved on the outer wall of the push rod. The valve seat is fixedly installed at the lower part of the valve body. The valve seat and the valve body are sealed with an interference fit, and the conical sealing surface of the valve seat and the semi-circular bottom of the push rod form a linear seal. The bottom of the solenoid valve body is fitted with an interference fit end filter, and a steel ball is embedded between the end filter and the valve body.

2. The spring-loaded push rod type large-diameter normally open solenoid valve for EHB energy recovery according to claim 1, characterized in that: The push rod diameter is set to be thicker at the top and thinner at the bottom, and the valve body inner wall diameter is thinner at the top and thicker at the bottom. An annular cavity is formed between the lower end face of the thick section of the push rod and the upper end face of the thick section of the valve body, and the annular cavity is located in the middle of the valve body.

3. A spring-loaded push rod type large-diameter normally open solenoid valve for EHB energy recovery according to claim 2, characterized in that: The return spring is sleeved on the thin section of the push rod and located in the annular cavity, and is limited by the lower end face of the thick section of the push rod and the upper end face of the thick section of the valve body.

4. A spring-loaded push rod type large-diameter normally open solenoid valve for EHB energy recovery according to claim 1, characterized in that: A platform is provided at the top of the moving iron, and a pressure balance chamber is formed between the magnetic shielding tube and the top of the moving iron through the platform.

5. A spring-loaded push rod type large-diameter normally open solenoid valve for EHB energy recovery according to claim 1, characterized in that: The diameter of the semi-circular shape at the bottom of the push rod is 3.1mm ± 0.05mm, and the cone angle of the valve seat cone is 80° ± 2°.

6. A spring-loaded push rod type large-diameter normally open solenoid valve for EHB energy recovery according to claim 5, characterized in that: The push rod is linked to the moving iron, and its stroke is optimized through hydraulic simulation to ensure that the opening between the push rod and the valve seat meets the flow channel with an orifice diameter of 2.2mm.

7. A spring-loaded push rod type large-diameter normally open solenoid valve for EHB energy recovery according to claim 1, characterized in that: The flange face of the magnetic shielding tube is press-fitted to the valve body with an interference fit using tooling, and the pressing force is 150-200N.

8. An assembly method for the solenoid valve according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Valve seat preload: Place the valve seat at the bottom of the valve body and apply a preload of 100N to preload the valve seat into the valve body; S2. Push rod assembly: Install the return spring and push rod in sequence, fine press the valve seat to make the valve seat and valve body seal to an interference fit, and control the air pressure. S3. Moving iron assembly: The moving iron is installed in the magnetic shielding tube, and the moving iron and magnetic shielding tube are pressed in as a whole from the top of the valve body; S4. Magnetic shielding tube seal: Pressure is applied to the flange face of the magnetic shielding tube using a tooling to make the magnetic shielding tube and the valve body fit together and achieve an interference seal; S5. End filter installation: Install an end filter at the bottom of the valve body.

9. The assembly method according to claim 8, characterized in that: In step S2, the interference fit between the valve seat and the valve body after fine pressing is 0.02-0.03 mm.

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