Pneumatic actuator and pneumatic control system

Abstract

The utility model provides pneumatic actuator and pneumatic control system, wherein, pneumatic actuator includes: the cylinder body of cavity formation, the cavity is divided into first chamber and second chamber with split piston assembly, split piston assembly includes main piston and limit piston, limit piston positive block main piston, the inside of cavity is equipped with first axial stop for reverse blocking limit piston, the both ends of main piston are connected with a push rod and a core respectively, push rod has the protruding end of outward protruding from the first end of cylinder body, and the core protrudes outward through the second end of cylinder body, position sensor sets up at the second end of cylinder body, detects the position of core. The utility model discloses pneumatic actuator can switch among three positions, and can realize closed loop feedback through position sensor, and the structure is simple, and the position detection is accurate, improves integrated and installation convenience.

Description

Technical Field

[0001] This utility model relates to the field of automotive parts, specifically to pneumatic actuators and pneumatic control systems. Background Technology

[0002] In heavy commercial vehicles, construction machinery, and other fields, combined transmissions are commonly used to expand the gear ratio range of the transmission and improve the vehicle's power and economy. A combined transmission typically consists of a main transmission and one or more auxiliary transmissions (such as a split-speed auxiliary transmission or a range auxiliary transmission). Gear shifting in the auxiliary transmissions relies on actuators, and pneumatic actuators are widely used in this field due to their high power density, fast response speed, high reliability, and relatively low cost.

[0003] Traditional auxiliary transmission pneumatic actuators are typically two-position (i.e., high / low gear or odd / even gear), switching between the two positions by opening and closing a single air passage. However, with the development of transmission technology, the requirements for shift logic and smoothness are becoming increasingly stringent, especially in certain complex shift sequences, where an actuator capable of stably remaining in an intermediate position (i.e., neutral position) is needed. For example, in conditions such as pre-selection or coasting in neutral, an actuator in the neutral position can disconnect power transmission, reduce resistance, and improve fuel economy.

[0004] Specifically, the existing technology has the following main drawbacks: Structural complexity and size issues: To achieve three-position functionality, many solutions require the introduction of additional pistons, chambers, or complex linkage mechanisms, resulting in a significant increase in the overall size of the actuator (especially the axial length), making it difficult to arrange in the compact space of the gearbox sidewall.

[0005] Insufficient control precision and stability: Maintaining the neutral position often depends on the precise balance of pressure in the two chambers, which is difficult to maintain in the event of pressure fluctuations or leaks, easily leading to position drift and affecting shifting reliability.

[0006] The position detection solution is outdated: mechanical limit switches or external sensors are used, which not only take up space, but are also prone to failure due to vibration, oil stains and other working conditions, resulting in a short lifespan and insufficient signal accuracy.

[0007] Poor integration and installation convenience: The lack of standardized and rigid interface design requires complex adapters to connect with the customer's gearbox, which increases installation costs and the probability of errors.

[0008] In view of this, the present invention provides a three-position pneumatic actuator that is compact in structure, reliable in control, accurate in position detection, and easy to integrate and install.

[0009] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this utility model, and therefore may include information that does not constitute prior art known to those skilled in the art. Utility Model Content

[0010] In view of this, the present invention provides a pneumatic actuator and a pneumatic control system to at least solve the problem of complex structure of three-position pneumatic actuators.

[0011] This utility model provides a pneumatic actuator, comprising: A cylinder body with an internal cavity; A split-type piston assembly is slidably disposed within the cavity, dividing the cavity into a first chamber and a second chamber. The split-type piston assembly includes a main piston and a limiting piston slidably fitted onto the main piston. The main piston has a first main piston outer wall surface that slidably engages with a first inner wall surface of the cavity and a second main piston outer wall surface that slidably engages with the inner wall surface of the limiting piston. A first axial stop for the limiting piston is formed on a main piston ring shoulder between the first main piston outer wall surface and the second main piston outer wall surface (which has a reduced diameter). The limiting piston has a first limiting piston outer wall surface that slidably engages with the first inner wall surface of the cavity and a second inner wall surface of the cavity. The outer wall surface of the second limiting piston forms a second axial stop between the outer wall surface of the first limiting piston and the outer wall surface of the second limiting piston with an increased diameter. The second axial stop cooperates with the inner shoulder of the cavity to limit the axial position of the limiting piston. The inner shoulder separates the first inner wall surface and the second inner wall surface with an increased diameter. A push rod and an iron core are respectively connected to both ends of the main piston. The push rod has an extension end extending outward from the first end of the cylinder body. The iron core extends outward through the second end of the cylinder body. A position sensor is disposed at the second end of the cylinder body, surrounds the iron core, and is used to detect the axial position of the iron core.

[0012] The pneumatic actuator can have a compact structural size and a simpler structure compared to existing technologies.

[0013] Preferably, the position sensor is a non-contact sleeve-type magnetic induction sensor, and the iron core moves with the main piston and partially inserts into the sensing area of ​​the position sensor; the position sensor determines the position of the main piston by detecting the change in magnetic field strength caused by the change in the insertion depth of the iron core.

[0014] Preferably, it further includes a solenoid valve body, the solenoid valve body including a first solenoid valve for controlling the loading and unloading of compressed air in the first chamber and a second solenoid valve for controlling the loading and unloading of compressed air in the second chamber.

[0015] Preferably, it further includes a flange plate with a through hole, the second end of the cylinder body is provided with a flange connection structure, the first side of the flange plate is screwed to the flange connection structure, the iron core extends out of the flange plate, and the position sensor is screwed to the second side of the flange plate.

[0016] Preferably, the first end of the cylinder body axially limits the first chamber, and the second end of the cylinder body axially limits the second chamber.

[0017] Preferably, the main piston has a first sealing ring that surrounds the outer wall of the first main piston and a second sealing ring that surrounds the outer wall of the second main piston.

[0018] Preferably, the limiting piston has a third sealing ring that surrounds the outer wall of the second limiting piston in a circumferential manner.

[0019] This utility model also provides a pneumatic control system, which is equipped with the pneumatic actuator as described above.

[0020] This pneumatic control system can have the advantages brought by the pneumatic actuator.

[0021] Preferably, the pneumatic control system is configured for a vehicle, such as a passenger car or a commercial vehicle.

[0022] Preferably, the pneumatic control system is configured as a gearbox system, and the pneumatic actuator is used to operate the shifting mechanism of the gearbox system.

[0023] This application may have at least some of the following beneficial effects compared with the prior art: Compact structure and short axial dimension: It adopts the structure of main and auxiliary piston set, and uses the relative movement of the two pistons and the stepped stop on the cylinder body to achieve precise positioning of the neutral position. It eliminates the need for the third intermediate chamber or additional mechanical positioning device required by traditional three-position cylinders, making the overall structure of the actuator very compact, especially suitable for installation on the side wall of the gearbox where space is limited.

[0024] The three positions are stable and reliable: the neutral position is maintained by the combined action of air pressure on both sides and mechanical stops, ensuring good stability, strong anti-interference ability, and resistance to deviation from the position due to minor air pressure fluctuations. The extended and retracted positions are guaranteed by the end of the mechanical stroke and air pressure on one side, ensuring high positional certainty.

[0025] Precise and reliable position detection: An integrated non-contact magnetic induction position sensor detects position by sensing changes in the magnetic field caused by the movement of the iron core as the piston moves. This method is wear-free, long-lasting, contamination-resistant, and highly accurate, providing real-time and accurate position feedback to the transmission control unit, which is the foundation for intelligent shifting and fault diagnosis.

[0026] The control logic is simple and efficient: only two standard two-position three-way solenoid valves are needed. The switching of the three positions can be reliably achieved through simple "double-way" and "one on and one off" logic. The control strategy is simple and highly reliable.

[0027] Modular design and easy integration: The solenoid valve and position sensor are highly integrated into the actuator body, reducing external piping and joints and lowering the risk of leakage. The standardized flange connection interface design allows the actuator to be easily, quickly, and reliably installed on gearboxes of different customers, greatly improving product versatility and assembly efficiency.

[0028] High output force and superior performance: Under the standard working air pressure of 8 bar, both the extended and retracted positions can provide a theoretical output force of more than 1300N, with the retracted position having a greater force (1900N), which can meet the force requirements of heavy-duty gearbox shifting and ensure proper shifting.

[0029] This utility model provides a pneumatic actuator and a pneumatic control system that can switch between three positions and achieve closed-loop feedback through a position sensor. It has a simple structure, accurate position detection, and improves the convenience of integration and installation.

[0030] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit the present invention. Attached Figure Description

[0031] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments conforming to the present invention and, together with the description, serve to explain the principles of the present invention. It is obvious that the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0032] Figure 1 This is a schematic diagram of the structure of a pneumatic actuator provided in an embodiment of this application.

[0033] Figure 2 This is another structural schematic diagram of a pneumatic actuator provided in an embodiment of this application.

[0034] Figure 3 This is another structural schematic diagram of a pneumatic actuator provided in an embodiment of this application.

[0035] Figure 4 This is another structural schematic diagram of a pneumatic actuator provided in an embodiment of this application.

[0036] Figure 5 This is a schematic diagram of the first working state of a pneumatic actuator provided in an embodiment of this application.

[0037] Figure 6 yes Figure 5 A magnified view of a portion of the image.

[0038] Figure 7 yes Figure 6 A magnified view of a portion of the image.

[0039] Figure 8 This is a schematic diagram of the second working state of a pneumatic actuator provided in an embodiment of this application.

[0040] Figure 9 yes Figure 8 A magnified view of a portion of the image.

[0041] Figure 10 This is a schematic diagram of the third working state of a pneumatic actuator provided in an embodiment of this application.

[0042] Figure 11 yes Figure 10 A magnified view of a portion of the image.

[0043] Figure label: Detailed Implementation

[0044] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present invention will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore repeated descriptions of them will be omitted.

[0045] The use of terms such as "first," "second," and similar words in the specific description does not indicate any order, quantity, or importance, but is merely used to distinguish different components. Furthermore, in the description of this utility model, terms such as "upper," "lower," etc., indicate orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings. These are merely for ease of description and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on this utility model.

[0046] It should be noted that, unless otherwise specified, the embodiments of this utility model and the features in different embodiments can be combined with each other.

[0047] Figure 1 This is a schematic diagram of the structure of a pneumatic actuator provided in an embodiment of this application. Figure 2 This is another structural schematic diagram of a pneumatic actuator provided in an embodiment of this application. Figure 3 This is another structural schematic diagram of a pneumatic actuator provided in an embodiment of this application. Figure 4 This is another structural schematic diagram of a pneumatic actuator provided in an embodiment of this application. Figure 5 This is a schematic diagram of the first working state of a pneumatic actuator provided in an embodiment of this application. Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5As shown, this utility model provides a pneumatic actuator, including: a cylinder body 1, a main piston 5, a push rod 2, an iron core 7, a limiting piston 6, and a position sensor 4. The cylinder body 1 has an internal cavity; a split piston assembly is slidably disposed within the cavity, dividing the cavity into a first chamber 9 (push rod side chamber) and a second chamber 10 (back side chamber). The split piston assembly includes the main piston 5 and a limiting piston 6 slidably fitted onto the main piston 5. The main piston 5 has a first main piston outer wall surface 53 that slidably engages with a first inner wall surface 101 of the cavity, and a second main piston outer wall surface 54 that slidably engages with the inner wall surface of the limiting piston 6. A first axial stop 11 for limiting the piston 6 is formed between the first main piston outer wall surface 53 and the second main piston outer wall surface 54, which has a reduced diameter. That is, the main piston ring shoulder (i.e., the first axial stop 11) of the main piston 5 abuts against the end face of the limiting piston 6. The limiting piston 6 has a first limiting piston outer wall surface 62 that slides in cooperation with the first inner wall surface 101 of the cavity, and a second limiting piston outer wall surface 63 that slides in cooperation with the second inner wall surface 102 of the cavity. A limiting piston ring shoulder between the first limiting piston outer wall surface 62 and the second limiting piston outer wall surface 63 with an increased diameter forms a second axial stop portion 12. The second axial stop portion 12 cooperates with the inner shoulder 103 of the cavity to limit the axial position of the limiting piston 6. The inner shoulder 103 of the cavity separates the first inner wall surface 101 and the second inner wall surface 102 with an increased diameter. A push rod 2 and an iron core 7 are respectively connected to the two ends of the main piston 5. The push rod 2 has an extension end that extends outward from the first end (push rod end / right end) of the cylinder body 1. The iron core 7 extends outward through the second end of the cylinder body 1. A position sensor 4 is disposed at the second end (iron core end / left end) of the cylinder body 1, rings the iron core 7, and is used to detect the axial position of the iron core 7. In this invention, besides controlling the main piston 5 at both ends of the cavity by separately introducing air into the first chamber 9 and the second chamber 10, air can also be introduced into the first chamber 9 and the second chamber 10 simultaneously. The main piston 5 can be bidirectionally limited to stabilize it in the middle of the cavity, thereby achieving the change of the main piston 5 in three positions within the cavity (left, middle, and right positions correspond to different subsequent control signals) through two pneumatic pipelines. The position sensor 4 is located at the second end of the cylinder body 1, ringing the travel range of the iron core 7, and detecting the position of the iron core 7. The position sensor 4 is used to detect changes in the internal magnetic field strength or distribution caused by changes in the axial position of the iron core to generate control signals for gear switching. This invention, through an innovative mechanical design that combines a split piston assembly with a stepped cavity, along with highly integrated non-contact position sensing technology and a modular flange interface, provides a pneumatic actuator with short axial dimensions, reliable three-position stability, accurate detection, simple control, and convenient installation.This actuator is particularly suitable for shift control of combined transmissions in commercial vehicles and construction machinery where space is limited and reliability requirements are extremely high, and it has good industrialization prospects and market value.

[0048] Figure 5 This is a schematic diagram of the first working state of a pneumatic actuator provided in an embodiment of this application. Figure 6 yes Figure 5 A magnified view of a portion of the image. Figure 7 yes Figure 6 A magnified view of a portion of the image. In some embodiments, such as... Figure 5 , 6 As shown in Figure 7, when the first solenoid valve 31 is open and the second solenoid valve 32 is closed, the main piston 5 and the limiting piston 6 jointly compress the second chamber 10 (equivalent to the main piston 5 and the limiting piston 6 being pressed to the second end of the chamber). At this time, the iron core 7 is located at the innermost end of the detection range of the position sensor 4, and the pneumatic actuator is in the retracted position, but not limited to this position.

[0049] Figure 8 This is a schematic diagram of the second working state of a pneumatic actuator provided in an embodiment of this application. Figure 9 yes Figure 8 A magnified view of a portion of the image. In some embodiments, such as... Figure 8 , 9 As shown, when the first solenoid valve 31 and the second solenoid valve 32 are opened simultaneously, high-pressure gas (such as 8-10 Bar) enters the first chamber 9 and the second chamber 10 at the same time. The second axial stop 12 of the limiting piston 6 is limited to the inner shoulder 103 of the chamber, and the first axial stop 11 of the main piston 5 is limited to the end face of the limiting piston 6, so that the main piston 5 is bidirectionally limited and located in the middle of the chamber. At this time, the iron core 7 is located in the middle of the detection range of the position sensor 4, and the pneumatic actuator is in a neutral position, but not limited to this position. Figure 10 This is a schematic diagram of the third working state of a pneumatic actuator provided in an embodiment of this application. Figure 11 yes Figure 10 A magnified view of a portion of the image. For example... Figure 10 , 11 As shown, in some embodiments, when the first solenoid valve 31 is closed and the second solenoid valve 32 is open, the second axial stop 12 of the limiting piston 6 is limited to the inner shoulder 103 of the cavity, and the main piston 5 compresses the first chamber 9 (equivalent to the main piston 5 being pressed to the first end of the cavity). At this time, the iron core 7 is located at the outermost end of the detection range of the position sensor 4, and the pneumatic actuator is in the extended position, but not limited to this.

[0050] In some embodiments, the position sensor 4 is a non-contact sleeve-type magnetic induction sensor. The iron core 7 moves with the main piston 5 and is partially inserted into the sensing area of ​​the position sensor 4 (e.g., into the central sensing hole of the position sensor). The position sensor continuously or in stages determines the precise axial position of the main piston by detecting changes in the internal magnetic field strength or distribution caused by changes in the insertion depth of the iron core. This solution has no physical contact, no wear, strong anti-contamination ability, long life, and high signal accuracy, but it is not limited thereto.

[0051] In some embodiments, a solenoid valve body 3 is also included. The solenoid valve body 3 includes a first solenoid valve 31 for controlling the loading and unloading of compressed air in the first chamber 9 and a second solenoid valve 32 for controlling the loading and unloading of compressed air in the second chamber 10. The air inlets of the two solenoid valves may be connected to the same air source, but are not limited thereto.

[0052] In some embodiments, a flange plate 8 with a through hole is further included. The second end of the cylinder body 1 is provided with a flange connection structure. The flange connection structure is screwed onto the first side of the flange plate 8. The iron core 7 extends out of the flange plate 8. The position sensor 4 is screwed onto the second side of the flange plate 8, but this is not a limitation. This modular flange connection design standardizes the installation, replacement, and interface with the gearbox of the position sensor, greatly improving installation convenience and versatility.

[0053] In some embodiments, the first end of the cylinder body 1 axially limits the first chamber 9, and the second end of the cylinder body 1 axially limits the second chamber 10, but is not limited thereto.

[0054] In some embodiments, the limiting piston 6 is a tubular component. The first end of the tubular component moves axially along the first chamber 9, and the outer periphery of the second end of the tubular component is provided with a limiting piston ring shoulder (not shown in the figure). The limiting piston ring shoulder is stopped by the inner shoulder platform 103 of the cavity, but is not limited thereto. Specifically, in this embodiment, the inner wall of the cavity is provided with an inner shoulder platform, such that the inner diameter of the first chamber (usually the push rod side chamber) is smaller than the inner diameter of the second chamber (usually the back side chamber). The limiting piston is a hollow tubular component. The first end (small diameter end) of the tubular component extends into the first chamber and can slide axially therein. The outer periphery of the second end (large diameter end) of the tubular component is provided with a limiting piston ring shoulder. When the limiting piston moves axially in the second direction, the limiting piston ring shoulder abuts against the inner shoulder platform of the cylinder body, thereby forming a first axial stop.

[0055] In some embodiments, the limiting piston is provided with a third sealing ring 61 that surrounds the outer wall surface 63 of the second limiting piston in a circumferential manner, but this is not a limitation. The third sealing ring makes sliding sealing contact with the inner wall of the second chamber 10, providing both sliding damping to ensure smooth movement and sealing to prevent gas leakage from the second chamber.

[0056] In some embodiments, the first end of the main piston 5 moves axially along the inner wall of the sleeve of the limiting piston 6, and the second end of the main piston 5 is provided with a main piston ring shoulder (not shown in the figure). The main piston ring shoulder moves axially to abut against the end face of the limiting piston 6, but is not limited thereto.

[0057] In some embodiments, the main piston is provided with a first sealing ring 51 that surrounds the outer wall surface 53 of the first main piston and a second sealing ring 52 that surrounds the outer wall surface 54 of the second main piston. The second sealing ring 52 slides and seals against the inner wall of the sleeve of the limiting piston 6 to provide damping and sealing, but is not limited thereto.

[0058] This utility model also provides a pneumatic control system, which is equipped with the pneumatic actuator described above. Because it uses the aforementioned pneumatic actuator, the pneumatic control system of this utility model can switch between three positions and achieve closed-loop feedback through a position sensor. It features a simple structure, accurate position detection, and improved integration and installation convenience. The relevant technical features have been described above and will not be repeated here.

[0059] In some embodiments, the pneumatic control system is configured for a vehicle, but is not limited thereto.

[0060] In some embodiments, the pneumatic control system is configured as a gearbox system, and the pneumatic actuator is used to operate the shifting mechanism of the gearbox system, but is not limited thereto.

[0061] The specific embodiments of the present invention are as follows: Reference Figures 1 to 11 This embodiment provides a three-position pneumatic actuator. The actuator mainly includes a cylinder body 1, a split piston assembly, a push rod 2, an iron core 7, a solenoid valve body 3, a position sensor 4, and a flange plate 8.

[0062] The cylinder body 1 is generally cylindrical, made of high-strength aluminum alloy or steel, and has a high-precision, smooth cylindrical cavity machined inside. This cavity is not of uniform diameter; it has an inward-facing inner shoulder in its center. This shoulder divides the cavity into two parts: the cavity portion closer to the push rod 2 has a smaller diameter and is defined as the first chamber 9; the cavity portion farther from the push rod 2 has a larger diameter and is defined as the second chamber 10. The end face of the inner shoulder forms an important mechanical limiting surface in the axial direction (i.e., the inner shoulder 103 used to mate with the second axial stop portion 12 of the limiting piston).

[0063] The split piston assembly consists of a main piston 5 and a limiting piston 6. The limiting piston 6 is a hollow, stepped sleeve-like component made of metal. Its small-diameter end (left end) can slide into the first chamber 9. A limiting piston ring shoulder is machined on the outer periphery of its large-diameter end. The diameter of this limiting piston ring shoulder (i.e., the second axial stop 12) is slightly smaller than the inner diameter of the second chamber 10, and its right end face can abut against the left end face of the inner shoulder 103 of the cylinder body 1. A groove is formed circumferentially on the limiting piston ring shoulder, in which a third sealing ring 61 (such as a step seal made of polytetrafluoroethylene composite material) is embedded to form a sliding seal with the inner wall of the second chamber 10 and provide appropriate damping.

[0064] The main piston 5 is a plunger-shaped component, its right end ( Figure 2 The main piston 5 (shown in the diagram) has a main piston ring shoulder. The main body of the main piston 5 passes through the center of the sleeve of the limiting piston 6, and the two can slide axially relative to each other. The diameter of the main piston ring shoulder is slightly smaller than the inner diameter of the first chamber 9, and its left end face can abut against the right end face of the small-diameter end of the limiting piston 6. A groove is formed circumferentially on the main piston ring shoulder, in which a first sealing ring 51 (such as an O-ring or Step seal) is embedded to form a sliding seal with the inner wall of the first chamber 9. A groove is also formed on the outer circumference of the left end of the main piston 5 (the end closer to the second chamber 10), in which a second sealing ring 52 is embedded to form a sliding seal with the inner wall of the sleeve of the limiting piston 6.

[0065] The push rod 2 is fixedly connected to the center of the right end of the main piston 5 by means of threads or snaps. The push rod 2 extends outward through the center hole (not shown in the figure) of the right end cover of the cylinder body 1, and a dustproof sealing ring is provided at this hole. The extended end of the push rod 2 is usually designed with a connecting pin hole or ball head for connecting with the shift fork of the gearbox.

[0066] The center of the left end of the main piston 5 is also fixedly connected to a cylindrical iron core 7 by means of threads or interference fit. The iron core 7 is made of a soft magnetic material with good magnetic permeability (such as low carbon steel).

[0067] The left end of the cylinder body 1 is machined with a flange connection structure, such as a ring of bolt holes. The flange plate 8 is a ring-shaped or disc-shaped metal plate with a through hole in the center for the iron core 7 to pass through. The right side of the flange plate 8 is fastened to the flange connection structure at the left end of the cylinder body 1 by multiple hexagonal socket head cap screws.

[0068] Position sensor 4 is a non-contact sleeve-type magnetic induction linear displacement sensor. Its housing is fixed to the left side of flange plate 8 by screws. Position sensor 4 has a sensing hole in its center, into which the left end of iron core 7 extends and can slide axially within the hole as the main piston 5 moves. Position sensor 4 contains a magnetic sensing element and signal processing circuitry, which can sensitively detect changes in the magnetic field within the sensing hole caused by changes in the insertion depth of iron core 7, and output a proportional electrical signal (such as voltage or PWM signal) to accurately reflect the real-time position of the main piston 5.

[0069] The solenoid valve body 3 is bolted to the top or side of the cylinder body 1. It integrates two independent two-position three-way solenoid valves: a first solenoid valve 31 and a second solenoid valve 32. The air inlets P of the two solenoid valves are connected in parallel and share a common air supply to the vehicle (typically an air tank, at a pressure of approximately 8-10 bar). The outlet of the first solenoid valve 31 is connected to the first chamber 9 via an air passage inside or outside the cylinder body 1. The outlet of the second solenoid valve 32 is connected to the second chamber 10 via another air passage. The exhaust ports R of both solenoid valves are typically open to the atmosphere or connected back to the muffler. An electrical interface is integrated on the solenoid valve body 3 for receiving control signals from the transmission control unit (TCU).

[0070] This embodiment illustrates the three working positions (retracted position, neutral position, and extended position) of the above-mentioned pneumatic actuator and their control principles, combined with... Figures 5 to 11 Please provide an explanation.

[0071] 1. Low Position / Retracted Position

[0072] Reference Figure 5 and Figure 7 When the actuator needs to be in the retracted position (e.g., corresponding to a low gear in the auxiliary transmission), the TCU controls the first solenoid valve 31 to open and the second solenoid valve 32 to close.

[0073] High-pressure gas enters the first chamber 9 through the opened first solenoid valve 31. The second solenoid valve 32 closes, connecting the second chamber 10 to the exhaust port. Initially, the split piston assembly may be in any position. Under the pressure of the gas in the first chamber 9, a resultant force F2 is generated, pushing the split piston assembly to the left (first axial direction). At this time, since there is no pressure in the second chamber 10, there is no tendency for relative movement between the main piston 5 and the limiting piston 6, and the main piston ring shoulder of the main piston 5 remains in contact with the end face of the limiting piston 6 (or they are mechanically integrated in this direction of movement). The split piston assembly (the main piston 5 and the limiting piston 6 as a whole) moves to the left together.

[0074] The split piston assembly continues to move to the left until the main piston 5 and the limiting piston 6 move to their limit together. The second axial stop 12 of the limiting piston 6 abuts against the inner shoulder 103 of the cavity, and at the same time, the main piston ring shoulder (first axial stop 11) of the main piston 5 is also in close contact with the end face of the limiting piston 6. At this point, the main piston 5 can no longer move to the left, and both the main piston 5 and the limiting piston 6 are in contact with the flange plate 8 at the left end of the cylinder body 1, and the actuator reaches the maximum retracted position. The push rod 2 retracts to its shortest length, outputting the maximum pulling force (e.g., 1900N at 8 bar). The position sensor 4 detects that the iron core 7 has moved to the leftmost end (the sensor is inserted to its deepest point) and outputs a retracted position signal.

[0075] 2. Neutral Position

[0076] Reference Figure 8 and Figure 9 When the actuator needs to be in a neutral position (i.e., neither in extension nor retraction), the transmission control unit (TCU) simultaneously sends an opening signal to the first solenoid valve 31 and the second solenoid valve 32.

[0077] High-pressure gas enters the solenoid valve body from a common gas source. The first solenoid valve 31, which is opened, introduces the high-pressure gas into the first chamber 9. At the same time, the second solenoid valve 32, which is opened, introduces the high-pressure gas into the second chamber 10. Under the action of the two gas pressures, the gas pressure in the second chamber 10 acts on the left side of the limiting piston ring shoulder of the limiting piston 6 and the left end face of the main piston 5 (through the iron core 7 connecting part, etc.), generating a force F1 that pushes the entire split piston assembly to the right (second axis).

[0078] The gas pressure in the first chamber 9 acts on the right side of the main piston ring shoulder of the main piston 5, generating a force F2 that pushes the main piston 5 to the left (first axial direction). At the same time, this pressure also acts on the right side of the small-diameter end of the limiting piston 6, but due to its small area, the force generated to the left is smaller.

[0079] Because the diameter of the first chamber 9 is smaller, the effective pressure-bearing area of ​​the main piston ring shoulder on the main piston 5 is limited; while the diameter of the second chamber 10 is larger, and its effective area is greater. Therefore, under the same gas pressure, F1 is significantly greater than F2. This causes the split piston assembly to have a tendency to move to the right as a whole.

[0080] The split piston assembly moves to the right as a whole until the right end face of the limiting piston ring shoulder of the limiting piston 6 is in close contact with the left end face of the inner shoulder 103 of the cylinder body 1. At this point, the limiting piston 6 is mechanically limited and cannot move further to the right. After the limiting piston 6 is limited by the inner shoulder 103, it is fixed relative to the cylinder body 1. At this time, the gas pressure F1 in the second chamber 10 mainly acts on the fixed limiting piston 6 (continuously generating a force to the left, but which is canceled by the inner shoulder 103) and on the left end of the main piston 5, continuing to push the main piston 5 to the right. Meanwhile, the gas pressure F2 in the first chamber 9 acts on the main piston 5, attempting to push it to the left.

[0081] Since the main piston 5 is free, it will seek an equilibrium position under the combined action of gas pressure F1 (to the right) and gas pressure F2 (to the left). Because the limiting piston 6 is fixed, when the main piston 5 moves to the left, the left end face of its main piston ring shoulder will approach the right end face of the small-diameter end of the limiting piston 6. In fact, during this balancing process, the main piston 5 will move slightly to the left until the left end face of its main piston ring shoulder makes slight contact with or maintains a very small gap (contact during pressure fluctuations) with the end face of the limiting piston 6. Ultimately, the main piston 5 is "clamped" between the gas pressure thrust from the second chamber 10 (attempting to move it to the right, but indirectly limited by the mechanical obstruction of the inner shoulder 103) and the gas pressure thrust from the first chamber 9 (moving it to the left, and directly mechanically blocked by the end face of the limiting piston 6), with mechanical stops in both directions providing final limiting protection. Therefore, the main piston 5 is held extremely stably in a precise axial intermediate position, i.e., the neutral position. Position sensor 4 detects the insertion depth of iron core 7 at this time (iron core 7 is located in the middle of its movement stroke) and outputs the corresponding neutral position signal.

[0082] 3. High Position / Extended Position

[0083] Reference Figure 10 and Figure 11 When the actuator needs to be in the extended position (e.g., corresponding to the high gear of the auxiliary transmission), the TCU controls the second solenoid valve 32 to open and the first solenoid valve 31 to close.

[0084] High-pressure gas enters the second chamber 10 through the opened second solenoid valve 32. The first solenoid valve 31 closes, connecting the first chamber 9 to the exhaust port. Gas pressure F1 acts on the left side of the main piston ring shoulder of the main piston 5, generating a resultant force that pushes the main piston 5 to the right (second axial direction). Under the action of gas pressure F1, the main piston 5 tends to move to the right. At the same time, due to the low pressure in the first chamber 9, the limiting piston 6 may be affected by residual gas pressure or friction on its right side, but its movement is restricted by the shoulder 103 inside the chamber. In practice, when it is necessary to reach the extended position, the limiting piston 6 is usually already or will be pushed to and held in contact with the shoulder 103 inside the chamber (e.g., when switching from the neutral position, or by prioritizing its reset through the gas path design).

[0085] After the limiting piston 6 is fixed by the shoulder 103 inside the cavity, the main piston 5, driven by the gas pressure F1, continues to slide to the right (second axis) relative to the stationary limiting piston 6. The main piston 5 continues to move to the right until it reaches the limit of the mechanical stroke. This limit may be formed by one or a combination of the following: other parts of the main piston 5 are in contact with the end cap of the cylinder body 1; or other dedicated limiting structures are designed (not shown in the figure). At this time, the actuator is in the extended position. The push rod 2 extends to its maximum length and outputs the maximum thrust (e.g., 1329 N at 8 bar). The position sensor 4 detects that the iron core 7 has moved to the rightmost end and outputs an extended position signal. Compared with the traditional prior art, the differences and progress of this utility model are mainly reflected in: Split-type piston assembly structure: Existing technologies may use a single piston or different forms of dual pistons. This utility model adopts a unique split-type design of "a main piston nested with a relatively movable limiting piston", and achieves mechanical positioning of three positions by setting a simple step (shoulder platform inside the cavity) on the cylinder body, making the structure more compact and ingenious.

[0086] Position detection integration method: Existing technologies may employ external sensors or sensors based on different principles. This invention directly integrates a non-contact magnetic induction sleeve sensor into the rear end of the cylinder body, and detects the position through an iron core that moves with the piston, achieving a high degree of integration, wear-free operation, and high precision in the detection unit. This is key to achieving a compact structure and reliable detection.

[0087] Interface and Installation Method: Existing technologies may use long housings or other non-standard interfaces. This invention uses a standard flange plate 8 as the core interface component. One side connects to the actuator body and sensor, while the other side provides mounting holes and mating surfaces for connection to the gearbox, forming a modular and standardized "flange interface" solution, which greatly improves installation convenience and versatility. This is the main feature of this invention that makes it easy to integrate.

[0088] Housing structure: Existing technology uses a "long housing", while the present invention significantly shortens the axial length of the housing (cylinder body) through the above-mentioned compact design.

[0089] In summary, the pneumatic actuator and pneumatic control system of this invention can switch between three positions and achieve closed-loop feedback through position sensors. It has a simple structure, accurate position detection, and improves the convenience of integration and installation.

[0090] The above description, in conjunction with specific optional embodiments, provides a further detailed explanation of this utility model. It should not be construed that the specific implementation of this utility model is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of this utility model, and all such modifications or substitutions should be considered within the protection scope of this utility model.

Claims

1. A pneumatic actuator, characterized in that, include: A cylinder body (1) has a cavity inside; A split piston assembly is slidably disposed within the cavity, dividing the cavity into a first chamber (9) and a second chamber (10). The split piston assembly includes a main piston (5) and a limiting piston (6) slidably fitted onto the main piston (5). The main piston (5) has a first main piston outer wall surface (53) that slidably engages with a first inner wall surface (101) of the cavity and a second main piston outer wall surface (54) that slidably engages with the inner wall surface of the limiting piston (6). A first axial stop (11) for the limiting piston (6) is formed between the first main piston outer wall surface (53) and the second main piston outer wall surface (54) with a reduced diameter. The limiting piston (6) has a first limiting piston outer wall surface (62) that slides with the first inner wall surface (101) of the cavity and a second limiting piston outer wall surface (63) that slides with the second inner wall surface (102) of the cavity. A second axial stop (12) is formed between the limiting piston ring shoulder between the first limiting piston outer wall surface (62) and the second limiting piston outer wall surface (63) with an increased diameter. The second axial stop (12) cooperates with the inner shoulder platform (103) of the cavity to limit the axial position of the limiting piston (6). The inner shoulder platform (103) of the cavity separates the first inner wall surface (101) and the second inner wall surface (102) with an increased diameter. The main piston (5) is connected to a push rod (2) and an iron core (7) at its two ends respectively. The push rod (2) has an extension end that extends outward from the first end of the cylinder body (1). The iron core (7) extends outward through the second end of the cylinder body (1). A position sensor (4) is set at the second end of the cylinder body (1), surrounds the iron core (7), and is used to detect the axial position of the iron core (7).

2. The pneumatic actuator according to claim 1, characterized in that, The position sensor (4) is a non-contact sleeve-type magnetic induction sensor. The iron core (7) moves with the main piston (5) and is partially inserted into the sensing area of ​​the position sensor (4). The position sensor (4) determines the position of the main piston (5) by detecting the change in magnetic field strength caused by the change in the insertion depth of the iron core (7).

3. The pneumatic actuator according to claim 1, characterized in that, It also includes a solenoid valve body (3), which includes a first solenoid valve (31) for controlling the loading and unloading of compressed air in the first chamber (9) and a second solenoid valve (32) for controlling the loading and unloading of compressed air in the second chamber (10).

4. The pneumatic actuator according to claim 1, characterized in that, It also includes a flange plate (8) with a through hole, the second end of the cylinder body (1) is provided with a flange connection structure, the first side of the flange plate (8) is screwed to the flange connection structure, the iron core (7) extends out of the flange plate (8), and the position sensor (4) is screwed to the second side of the flange plate (8).

5. The pneumatic actuator according to claim 1, characterized in that, The first end of the cylinder body (1) axially limits the first chamber (9), and the second end of the cylinder body (1) axially limits the second chamber (10).

6. The pneumatic actuator according to claim 1, characterized in that, The main piston has a first sealing ring (51) that surrounds the outer wall surface (53) of the first main piston and a second sealing ring (52) that surrounds the outer wall surface (54) of the second main piston.

7. The pneumatic actuator according to claim 1, characterized in that, The limiting piston is provided with a third sealing ring (61) that surrounds the second limiting piston outer wall surface (63) in a circumferential manner.

8. A pneumatic control system, characterized in that, The pneumatic control system is equipped with a pneumatic actuator as described in any one of claims 1 to 7.

9. The pneumatic control system as described in claim 8, characterized in that, The pneumatic control system is configured for use in vehicles.

10. The pneumatic control system as described in claim 9, characterized in that, The pneumatic control system is configured as a gearbox system, and the pneumatic actuator is used to operate the shifting mechanism of the gearbox system.

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