Integrated built-in tank with air bag closed hydraulic drive joint

Abstract

This invention relates to the field of hydraulically driven hydraulic joint technology, specifically an integrated closed-loop hydraulically driven joint with a built-in oil tank and airbag. The joint includes an integrated housing, within which are integrated a motor pump unit, a built-in airbag atmospheric pressure compensation oil tank, a check valve integrated module, a bidirectional parallel safety valve, a four-piston bidirectional counter-push actuator, and an axial sliding helical gear transmission mechanism. The oil suction end of the motor pump unit is connected to the base, and the oil outlet end is connected to the four-piston drive chamber via the check valve. The four-piston bidirectional counter-push actuator and the axial sliding helical gear transmission mechanism are in transmission cooperation. The bidirectional axial counter-push of the pistons drives the helical gear to slide axially, and the helical gear rotation direction achieves linear-to-rotational torque conversion, completing the bidirectional rotation of the hydraulic joint. The oil tank is equipped with an airbag to compensate for oil thermal expansion, and the bidirectional parallel safety valve provides system overload protection. The entire system is a closed-loop self-circulating structure, achieving hydraulic self-locking and zero-power position maintenance when stationary, and finally outputting torque externally through the central shaft.

Description

Technical Field

[0001] This invention relates to the field of hydraulic drive hydraulic joint technology, specifically to an integrated closed hydraulic drive joint with a built-in oil tank and airbag. Background Technology

[0002] The drawbacks of traditional electro-hydraulic joints are: they require high-power motors, resulting in large overall size and high production costs; maintaining a static posture requires continuous power supply from the motor for locking force, leading to extremely high energy consumption under no-load conditions; they have low torque density, and are prone to problems such as overheating, step loss, and rotational wobbling under heavy-load conditions, resulting in poor positioning accuracy. Traditional valve-controlled hydraulic joints have the following drawbacks: numerous external pipelines and control valve groups, many sealing nodes, making them prone to oil leakage, and loose structure; they rely on valve group throttling to achieve directional and speed regulation, resulting in severe system response lag and low transmission efficiency; they cannot achieve a high degree of integration between hydraulic components and hydraulic joint structure, resulting in poor installation compatibility. The drawbacks of existing closed hydraulic systems are as follows: In a fully enclosed structure, the thermal expansion of hydraulic oil can easily lead to a sudden increase in internal pressure, damaging the housing, seals, and pump body; air can easily get into the oil circuit, causing cavitation, sluggish operation, and pressure fluctuations; the system cannot automatically replenish oil after internal leakage, which can easily lead to air suction and affect operational stability; the logic of the forward and reverse drive valve group is complex, high-pressure oil is prone to cross-contamination, and there is no dedicated piston drive structure adapted to sliding helical gears, making it impossible to achieve precise bidirectional transmission. Summary of the Invention

[0003] The purpose of this invention is to provide an integrated built-in oil tank with an airbag-type closed hydraulic drive joint to solve the driving problem of the hydraulic joint mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: An integrated closed-loop hydraulic joint with a built-in oil tank and airbag includes an integrated housing. Within the housing are a motor pump unit, a built-in airbag atmospheric pressure compensation oil tank, a check valve module, a bidirectional parallel safety valve, a four-piston bidirectional counter-push actuator, and an axial sliding helical gear transmission mechanism. The motor pump unit's suction end connects to the base, and its outlet end connects to the four-piston drive chamber via the check valve. The four-piston bidirectional counter-push actuator and the axial sliding helical gear transmission mechanism are coupled, with the pistons driving the helical gears axially through bidirectional axial counter-push. This, combined with the helical gear rotation, achieves linear-to-rotational torque conversion, completing the bidirectional rotation of the hydraulic joint. The oil tank contains an airbag to compensate for oil thermal expansion, and the bidirectional parallel safety valve provides overload protection. The system is a closed-loop self-circulating structure, achieving hydraulic self-locking and zero-power position maintenance when stationary, ultimately outputting torque through the central shaft.

[0005] Compared with the prior art, the beneficial effects of the present invention are: 1. The first four-piston coaxial bidirectional thrust actuator is designed to provide symmetrical driving force for axial sliding helical gear rings, solving the problem of unilateral drive and off-center load.

[0006] 2. An innovative axial sliding helical gear ring transmission structure is used to achieve efficient conversion of linear to rotational torque through the axial thrust of the piston and the helical gear helix angle.

[0007] 3. Precisely set the rotation direction of the multi-stage helical gear ring, with alternating clockwise and counterclockwise tooth engagement, to achieve precise bidirectional, interference-free transmission of the joint.

[0008] 4. The built-in atmospheric pressure airbag and two-way safety valve functions are separated to solve the problems of oil thermal expansion and impact overload protection respectively; the pump box has no seal and automatically vents, and the box and motor are sealed to prevent oil leakage, taking into account both venting and motor protection.

[0009] 5. The entire system is highly integrated, with closed-loop pump control and direct drive, which can directly replace traditional motor joints and valve-controlled hydraulic joints. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the internal structure of the protective cover of the present invention; Figure 3 This is a schematic diagram of the gear oil pump module of the present invention; Figure 4 This is a cross-sectional schematic diagram of the gear oil pump module of the present invention; Figure 5 This is a cross-sectional view of the fuel tank of the present invention; Figure 6 This is a schematic diagram of the workflow of the present invention.

[0011] In the attached diagram, the components represented by each number are as follows: 1. Hydraulic joint; 2. Integrated housing; 3. Motor pump assembly; 4. Oil tank; 5. First oil circuit; 6. Second oil circuit; 7. First gear; 8. Second gear; 9. Sealing mounting seat; 10. Base; 11. Oil supply pipe; 12. Airbag; 13. Oil discharge pipe; 14. Check valve integrated module; 15. Back pressure check valve; 16. Piston drive chamber; 18. Safety valve; 19. Motor. Detailed Implementation

[0012] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0013] This invention provides a technical solution: such as Figure 1 - Figure 6 The illustrated integrated closed-loop hydraulic joint with built-in oil tank and airbag includes an integrated housing 2. The integrated housing 2 houses a motor pump unit 3, a built-in airbag atmospheric pressure compensation oil tank, a check valve integrated module 14, a bidirectional parallel safety valve 18, a four-piston bidirectional thrust actuator, and an axial sliding helical gear transmission mechanism. The oil suction end of the motor pump unit 3 is connected to the oil tank 4, and the oil outlet end is connected to the four-piston drive chamber 16 via the check valve. The four-piston bidirectional thrust actuator and the axial sliding helical gear transmission mechanism are in transmission cooperation. The pistons drive the helical gears axially through bidirectional axial thrust, and the helical gear rotation direction achieves linear-rotation torque conversion, completing the bidirectional rotation of the hydraulic joint 1. The oil tank 4 is equipped with an airbag 12 to compensate for oil thermal expansion, and the bidirectional parallel safety valve 18 provides system overload protection. The system as a whole is a closed-loop self-circulating structure, achieving hydraulic self-locking and zero-power position maintenance when stationary, and finally outputting torque externally through the central shaft.

[0014] The motor pump unit 3 is equipped with a motor 19. The output end of the motor 19 is connected to a first gear 7 via a transmission shaft. The first gear 7 meshes with a second gear 8. A sealing mounting seat 9 is fixedly connected inside the motor pump unit 3. The first gear 7 and the second gear 8 are rotatably connected to the sealing mounting seat 9. A base 10 is fixedly connected to the bottom of the motor pump unit 3. The base 10 is connected to the area where the first gear 7 and the sealing mounting seat 9 are located. Symmetrical oil supply pipes 11 are fixedly connected inside the base 10. Each oil supply pipe 11 is connected to a corresponding first oil passage 5 and a second oil passage 6.

[0015] The four-piston bidirectional counter-pushing actuator is a coaxial stacked structure. The four pistons are arranged symmetrically in two groups and can perform synchronous axial counter-pushing motions in opposite directions along the central shaft. The two groups of pistons correspond to hydraulic joint 1 for forward and reverse rotation drive, with symmetrical thrust and no off-center load. The axial sliding helical gear ring transmission mechanism adopts an axially sliding helical gear ring with a specific helix angle. Both the tooth tip and tooth root are flat-top structures, and a tooth tip-supporting-tooth-root anti-sway meshing method is used. The rotation direction of each stage of the helical gear ring is set as follows: clockwise helical gear between the central shaft and the first-stage internal gear ring, counterclockwise helical gear between the second-stage external gear ring and the second-stage internal gear ring, and clockwise helical gear between the second-stage counterclockwise external gear ring and the cylinder liner internal gear. The alternating rotation directions of the multi-stage gear rings achieve interference-free transmission, and the final power output end is the central shaft. The check valve integrated module 14 includes two replenishing check valves on the oil tank side, one back pressure check valve 15 on each of the left and right piston oil circuits, and one non-back pressure oil outlet check valve. The main oil circuit and the replenishing oil circuit are completely separated, and there is no backflow of high-pressure oil. The oil tank 4 is an integrally formed atmospheric pressure cavity. The airbag 12 is sealed inside the oil tank and is not connected to the high-pressure oil circuit. It only absorbs the thermal expansion volume of the oil. The motor pump group 3 is a coaxial direct connection structure of the motor and the internal meshing gear ring pump. There is no seal between the pump body and the oil tank to achieve automatic venting. The oil tank and the motor are sealed to prevent oil intrusion. The bidirectional parallel safety valve 18 is located between the high-pressure chambers of the left and right pistons. It only opens to balance the chamber pressure when the system is overloaded and overpressured. It is independent of the thermal expansion compensation function of the airbag 12.

[0016] The motor pump unit 3 and the internal gear ring pump are coaxially directly connected. The motor output shaft directly serves as the rotor shaft of the gear ring pump, eliminating the need for couplings and connection gaps, resulting in high transmission efficiency and high coaxiality. The internal gear ring pump has a compact structure, stable operation, and low pressure pulsation, making it suitable for forward and reverse closed-loop operation. The internal leakage is controllable. No sealing structure is provided between the motor pump unit 3 and the base 10, allowing a small amount of internally leaked oil to flow back to the oil tank 4, achieving automatic venting of the oil circuit. A special seal is provided between the oil tank 4 and the motor 19 to prevent oil from entering the motor cavity and ensure the safe operation of the motor 19.

[0017] Oil tank 4 is an integrally formed cavity, belonging to the normal pressure cavity, and does not bear the high pressure of the system. It has no external oil tank or external pipeline. Oil tank 4 only undertakes the functions of oil replenishment and thermal expansion compensation. When the system is working normally, the main oil suction of the pump body comes from the piston circuit. Only when the oil volume is insufficient due to internal leakage of the system, oil is automatically replenished through the check valve. The oil tank has a built-in elastic air bag 12. The air bag 12 is in a normal pressure environment and is not connected to the high pressure oil circuit. It is only compressed when the hydraulic oil is heated and expands, absorbing the expansion volume and preventing abnormal rise in the internal pressure of the system. Oil tank 4 is equipped with two one-way check valves, which correspond to the forward and reverse oil replenishment of the pump body respectively. Only oil is allowed to enter the system from the oil tank, and high pressure oil backflow is strictly prohibited.

[0018] Check valve integrated module 14: 2 on the oil tank side (dedicated to forward and reverse oil replenishment), 2 on each side piston oil circuit (1 with back pressure check valve + 1 without back pressure oil outlet check valve); the oil suction side with back pressure ensures the reliability of hydraulic self-locking, and the oil outlet side without back pressure ensures the system response speed. The main oil circuit and the replenishment oil circuit are completely separated, and there is no cross pressure problem; bidirectional parallel safety valve 18: set between the high pressure chambers of the left and right pistons, it only opens when the hydraulic joint 1 is subjected to external impact or overload jamming, causing the chamber pressure to exceed the standard, quickly balancing the pressure of the two chambers, protecting the system components from damage, and is completely independent of the airbag thermal expansion compensation function.

[0019] The system employs a coaxial, stacked, four-piston, bidirectional thrust structure. The four pistons are divided into two groups, arranged symmetrically on the same axis. The two groups of pistons correspond to the forward and reverse drive oil circuits of hydraulic joint 1, respectively. They can slide synchronously in opposite directions along the central axis of hydraulic joint 1. The pistons and cylinders are sealed together to form independent, sealed, high-pressure drive chambers. The high-pressure oil output from the pump enters the corresponding piston chamber, pushing the two groups of pistons to move synchronously in opposite directions along the axial direction. One group of pistons slides axially in the forward direction, while the other group slides synchronously in the opposite direction. The thrust of the two groups of pistons is symmetrical and the force is balanced, completely avoiding the problems of uneven load, uneven wear, and rotational sway caused by unilateral thrust. While the pistons slide axially, their ends directly act on the sliding helical gear ring, pushing the helical gear ring to move synchronously axially, converting the bidirectional linear thrust of the pistons into the rotational driving force of the helical gear ring.

[0020] It is specially adapted to the sliding helical gear ring transmission structure, and realizes the forward and reverse axial drive of the helical gear ring through bidirectional counter-pushing. It precisely matches the helical gear helix angle and tooth direction, and realizes bidirectional, jam-free, and high-precision rotation of the hydraulic joint 1.

[0021] Transmission method: The transmission adopts axial sliding helical gear ring meshing transmission. The helical gear ring can slide along the central shaft along the thrust of the piston. At the same time, the conversion from linear motion to rotational motion is achieved by relying on the helix angle of the helical teeth. The gear ring meshing is backlash-free and the transmission rigidity is strong.

[0022] Helical gear helix angle and tooth direction: The helical gear ring adopts a customized helix angle, which is adapted to the piston axial stroke and the rotation angle of hydraulic joint 1 to ensure precise matching between the piston thrust stroke and the rotation angle of hydraulic joint 1; all helical teeth are flat-topped tooth structures, and the tooth top supports the tooth root to prevent swaying meshing, eliminating transmission backlash.

[0023] The four pistons push against each other in both directions, causing the corresponding helical gear ring to slide axially. The clockwise and counterclockwise helical gear rings mesh alternately, and the piston axial thrust is converted into rotational torque through the helix angle. The torque is transmitted and superimposed step by step, and finally drives the central shaft to realize the clockwise and counterclockwise bidirectional rotation of the hydraulic joint 1. The direction of the gear ring rotation is perfectly matched with the direction of the piston push, and there is no transmission interference.

[0024] When the motor is powered on, it rotates forward / reverse, causing the coaxial direct-drive internal meshing gear pump to operate. The pump body draws in hydraulic oil through the piston circuit with a back pressure check valve, completing the main oil suction. High-pressure oil enters the corresponding drive chamber of the four pistons through the oil outlet check valve, pushing the two sets of pistons to slide synchronously in both directions axially. The piston drives the axial sliding helical gear ring to move synchronously. The helical gear ring relies on the helix angle and the directional tooth direction to mesh, converting the linear thrust into rotational torque. The torque of the multi-stage directional helical gear ring is superimposed and transmitted step by step, ultimately driving the central shaft to achieve precise rotation of the hydraulic joint 1. A small amount of internally leaked oil from the pump body flows back to the oil tank 4, automatically expelling air from the oil circuit; When the system oil level is insufficient, oil tank 4 will automatically replenish oil through the oil replenishment check valve; When the oil temperature rises and the oil expands, the air bladder in the oil tank compresses and absorbs the volume to maintain the system's normal pressure. When hydraulic joint 1 is subjected to overload impact, safety valve 18 opens to release pressure and protect system components.

[0025] After hydraulic joint 1 reaches the designated position, the motor stops, all check valves close, the system hydraulically locks itself, and hydraulic joint 1 remains stationary with zero power consumption. It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0026] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A one-piece built-in oil tank with airbag closed hydraulic drive joint, characterized in that, Includes: an integrated housing, the integrated housing (2) integrates a motor pump group (3), a built-in airbag atmospheric pressure compensation oil tank, a check valve integrated module (14), a bidirectional parallel safety valve (18), a four-piston bidirectional counter-push actuator and an axial sliding helical gear transmission mechanism; the oil suction end of the motor pump group (3) is connected to the oil tank (4), and the oil outlet end is connected to the four-piston drive chamber (16) through the check valve; the four-piston bidirectional counter-push actuator and the axial sliding helical gear transmission mechanism are in transmission cooperation, and the helical gear is driven to slide axially through the bidirectional axial counter-push of the piston, and the linear-rotation torque conversion is achieved by cooperating with the helical gear rotation direction to complete the bidirectional rotation of the hydraulic joint 1; the oil tank (4) is equipped with an airbag (12) to realize oil thermal expansion compensation, and the bidirectional parallel safety valve (18) realizes system overload protection. The system as a whole is a closed self-circulation structure, and when stationary, it realizes hydraulic self-locking zero power consumption position retention, and finally outputs torque to the outside through the central shaft.

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