A hydraulic control system for a servo-driven oil cylinder

Abstract

The utility model belongs to hydraulic control technical field, concretely relates to a kind of hydraulic control system of servo drive oil cylinder, the system with single set of servo motor, rack and pinion cylinder, hydraulic cylinder and corresponding control valve group composition minimum closed control unit, control unit can be used alone or multiple unit combination use. Through servo motor drive rack and pinion cylinder conversion movement form, cooperate closed loop control to realize the accurate lifting control of single cylinder or multiple cylinders, with hydraulic control anti-impact advantage and mechanical transmission accuracy. Compared with conventional system, the utility model can greatly reduce installed power and outline size, improve response speed and conversion efficiency, reduce system heating, can better meet the use demand of new mechatronic product.

Description

Technical Field

[0001] This utility model belongs to the field of hydraulic control technology, specifically relating to a hydraulic control system for a servo-driven oil cylinder. Background Technology

[0002] There are two control methods for conventional servo-driven hydraulic cylinders: one is to drive the cylinder with a conventional pump source and a servo valve, and the other is to drive the cylinder with a servo pump source and a conventional valve. Both control methods have disadvantages such as large installed power of the hydraulic system, large size, slow response speed, low conversion efficiency, and serious heat generation. With the development of technology, mechatronic products have put forward higher requirements for power, space, efficiency and response. The conventional servo drive control method can obviously no longer meet the needs of use. Utility Model Content

[0003] This utility model provides a servo-driven hydraulic cylinder control system. Based on the reciprocating motion characteristics of the cylinder within its stroke, the system adopts a closed control unit, eliminating the need for a large hydraulic oil tank and auxiliary components. At the same time, it minimizes intermediate valve groups and pipelines, thereby reducing the system's installed power and size while significantly improving system efficiency.

[0004] To achieve the above objectives, this utility model provides the following technical solution:

[0005] A hydraulic control system for a servo-driven cylinder includes at least one minimum closed control unit, which includes a servo motor assembly, a rack and pinion cylinder, a hydraulic cylinder, and a control valve assembly; the control valve assembly includes a relief valve, three solenoid ball valves, two accumulators, and two pressure sensors.

[0006] The output shaft of the servo motor in the servo motor assembly is connected to the gear and rack cylinder. The gear and rack cylinder is connected to the upper and lower chambers of the hydraulic cylinder through an oil circuit, forming a closed loop.

[0007] The overflow valve is used to set the maximum operating pressure of the system;

[0008] The three solenoid ball valves respectively realize the functions of two-chamber floating of hydraulic cylinder, closed-loop oil leakage and oil replenishment, and pressure holding of the lower chamber of the cylinder;

[0009] Two accumulators correspond to the two chambers of the hydraulic cylinder, respectively, and play a role in stabilizing pressure and balancing volume changes; two pressure sensors monitor the pressure of the two chambers of the hydraulic cylinder in real time.

[0010] Furthermore, the servo motor assembly includes a servo motor, a servo controller, and a rotary encoder;

[0011] The servo controller receives pressure data from the pressure sensor and rotation speed data from the rotary encoder to form a closed-loop control, dynamically adjusting the speed and direction of the servo motor.

[0012] Furthermore, the gear and rack cylinder converts the rotary motion of the servo motor into the linear reciprocating motion of the cylinder rod, thereby generating pressurized oil to drive the hydraulic cylinder to lift and lower.

[0013] Furthermore, each minimum closed control unit operates independently to achieve single-cylinder lifting or lowering actions, and precisely regulates the hydraulic cylinder's lifting speed, output thrust or lowering speed, and return resistance through closed-loop control.

[0014] Furthermore, multiple minimum closed control units work together, and the closed-loop control of each unit is integrated into a large closed-loop control system to achieve motion control of multi-cylinder synchronous rise, differential rise, different thrust output or synchronous descent, differential descent, different resistance output.

[0015] The beneficial effects of this utility model are as follows:

[0016] (1) Based on the characteristics of the reciprocating motion of the cylinder within the stroke, this hydraulic control system adopts a closed control unit, which eliminates the need for a large hydraulic oil tank and auxiliary parts. At the same time, it minimizes the intermediate valve group and pipelines, thereby reducing the system's installed power and size while significantly improving system efficiency.

[0017] (2) The control unit can be used alone to meet the precise force and displacement control of a single cylinder during the lifting process, or multiple units can be used together to work in coordination to achieve real-time precise control of the lifting and lowering speed, output thrust and return resistance of each cylinder, and complete the overall synchronous lifting and lowering, differential lifting and lowering, different thrust output and return resistance and other action control. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the hydraulic control system of this utility model;

[0019] In the diagram: 1. Servo motor; 2. Gear and rack cylinder; 3. Overflow valve; 4. Solenoid ball valve one; 5. Solenoid ball valve two; 6. Solenoid ball valve three; 7. Accumulator; 8. Pressure sensor; 9. Hydraulic cylinder; 10. Servo controller. Detailed Implementation

[0020] To more clearly illustrate the embodiments of this utility model or the technical solutions in the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0021] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The embodiments cannot be described in detail here, but the embodiments of the present invention are not limited to the following embodiments.

[0022] Example: A hydraulic control system for a servo-driven cylinder, referenced. Figure 1 As shown, it includes at least one minimum closed control unit, wherein the minimum closed control unit includes a servo motor group, a gear and rack cylinder 2, a hydraulic cylinder 9, and a control valve group; the control valve group includes an overflow valve 3, a first electromagnetic ball valve 4, a second electromagnetic ball valve 5, a third electromagnetic ball valve 6, two accumulators 7, and two pressure sensors 8;

[0023] Specifically, in this embodiment, the servo motor assembly includes a servo motor 1, a servo controller 10, and a rotary encoder. The rotor shaft of the servo motor 1 is rigidly coupled to the input shaft of the rotary encoder. The output shaft of the servo motor 1 is connected to the rack and pinion cylinder 2, which is connected to the upper and lower chambers of the hydraulic cylinder 9 via oil circuits, forming a closed loop. The servo controller 10 outputs signals to dynamically control the speed of the servo motor 1, thereby controlling the output pressure and flow rate of the rack and pinion cylinder 2 to match the output power with the required power, thus reducing power loss. The lifting and lowering action of the hydraulic cylinder 9 is achieved by controlling the forward and reverse rotation of the servo motor 1.

[0024] The overflow valve 3 is used to set the maximum working pressure of the system and serves as a safety protection function.

[0025] The electromagnetic ball valve 4 is used to cut off the two chambers of the hydraulic cylinder 9 when the power is off, and when the power is restored, the two chambers of the hydraulic cylinder 9 are connected, and the hydraulic cylinder 9 floats.

[0026] When the second electromagnetic ball valve 5 is energized, it enables closed-loop oil leakage and oil replenishment;

[0027] When the electromagnetic ball valve 6 is de-energized, it enables the hydraulic cylinder 9 to maintain pressure in the lower chamber.

[0028] Accumulator 7 is arranged in each of the two chambers of hydraulic cylinder 9 to achieve system pressure stabilization; the accumulator 7 arranged in the lower chamber can also balance the volume change caused by the area difference between the two chambers of hydraulic cylinder 9.

[0029] Two pressure sensors 8 are arranged, one in each of the two chambers of the hydraulic cylinder 9, to monitor the pressure in the two chambers in real time. The pressure data is sent to the servo controller 10, which, together with the rotational speed data of the rotary encoder, realizes the closed-loop control of the system.

[0030] Hydraulic cylinder 9, as the actuator of the hydraulic system, is connected to the external load and realizes the load to move according to the set trajectory through the linear reciprocating motion of the piston cylinder.

[0031] This servo-driven hydraulic cylinder control system consists of a single servo motor, a rack and pinion cylinder, a main drive cylinder, and corresponding control valve groups, forming a minimum closed control unit. The control unit can be used individually or in combination.

[0032] When used alone, the specific working principle is as follows:

[0033] The servo controller 10 adjusts the control signal in real time based on the closed-loop control feedback data. By controlling the speed of the servo motor 1, it controls the output pressure and flow rate of the gear and rack cylinder 2. When the servo motor 1 rotates forward, the oil rod of the gear and rack cylinder 2 extends downward, and the compressed oil enters the lower chamber of the hydraulic cylinder 9 through the solenoid ball valve (where solenoid ball valve 4 is de-energized, and solenoid ball valves 5 and 6 are energized), driving the hydraulic cylinder 9 to rise. The oil in the upper chamber of the hydraulic cylinder 9 returns to the upper chamber of the gear and rack cylinder 2. When the servo motor 1 rotates in reverse, the oil rod of the gear and rack cylinder 2 extends upward, and the compressed oil enters the upper chamber of the hydraulic cylinder 9, driving the hydraulic cylinder 9 to fall. The oil in the lower chamber of the hydraulic cylinder 9 returns to the lower chamber of the gear and rack cylinder 2 through the solenoid ball valve (where solenoid ball valve 4 is de-energized, and solenoid ball valves 5 and 6 are energized). During the rising process, the servo controller 10 can form a closed-loop control by collecting speed and pressure signals to achieve real-time and precise control of the cylinder's rising speed and output thrust. During the descent process, the servo controller 10 can form a closed-loop control by collecting speed and pressure signals to achieve real-time and precise control of the descent speed and return resistance of the hydraulic cylinder 9.

[0034] Meanwhile, multiple closed control units can work together to integrate the closed-loop control of each control unit into a large closed-loop control system, enabling real-time and precise control of the lifting and lowering speed, output thrust, and return resistance of each hydraulic cylinder, and completing actions such as overall synchronous lifting and lowering, differential lifting and lowering, different thrust output, and return resistance.

[0035] The hydraulic control system provided by this utility model adopts a power unit of servo motor and gear rack cylinder, which converts the rotary motion of servo motor into the reciprocating motion of gear rack cylinder, thereby driving the oil cylinder to extend and retract, and achieves precise control of its motion through closed-loop control. This control method retains the shock-resistant advantages of hydraulic control, avoiding the impact caused by mechanical transmission, while minimizing hydraulic pipelines and control valve groups, reducing pressure fluctuations and response delays caused by hydraulic oil compression. The closed-loop control of the hydraulic system requires only an external pump to replenish some leaked oil, significantly reducing installed power compared to conventional hydraulic systems. The rack and pinion cylinder can be placed near the hydraulic cylinder according to space constraints, eliminating the need for a separate hydraulic system, while minimizing intermediate pipeline length, resulting in a significantly smaller overall system size compared to conventional hydraulic systems. The servo motor, equipped with a servo driver, adjusts the hydraulic cylinder's motion state in real time through closed-loop control of speed and pressure, further accelerating its response speed. This hydraulic control system represents a significant improvement over conventional servo control systems in terms of both precise single-cylinder lifting control and multi-cylinder lifting coordination control, in terms of installed power, size, response speed, conversion efficiency, and system heat generation, better meeting the requirements of new electromechanical-hydraulic integrated products for hydraulic systems.

[0036] In the description of this utility model, it should be noted that the terms "upper," "lower," "inner," and "back," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this utility model and simplifying the 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. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0037] Furthermore, in the description of this utility model, unless otherwise explicitly defined, the terms "installation," "connection," "joining," and "connector" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model in light of the specific circumstances.

[0038] In this utility model, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0039] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A hydraulic control system for a servo-driven cylinder, characterized in that, It includes at least one minimum closed control unit, which includes a servo motor assembly, a rack and pinion cylinder, a hydraulic cylinder, and a control valve assembly; the control valve assembly includes an overflow valve, three solenoid ball valves, two accumulators, and two pressure sensors. The output shaft of the servo motor in the servo motor assembly is connected to the gear and rack cylinder. The gear and rack cylinder is connected to the upper and lower chambers of the hydraulic cylinder through an oil circuit, forming a closed loop. The overflow valve is used to set the maximum operating pressure of the system; The three solenoid ball valves respectively realize the functions of two-chamber floating of hydraulic cylinder, closed-loop oil leakage and oil replenishment, and pressure holding of the lower chamber of the cylinder; Two accumulators correspond to the two chambers of the hydraulic cylinder, respectively, and play a role in stabilizing pressure and balancing volume changes; two pressure sensors monitor the pressure of the two chambers of the hydraulic cylinder in real time.

2. The hydraulic control system for the servo-driven cylinder according to claim 1, characterized in that, The servo motor assembly includes a servo motor, a servo controller, and a rotary encoder; The servo controller receives pressure data from the pressure sensor and rotation speed data from the rotary encoder to form a closed-loop control, dynamically adjusting the speed and direction of the servo motor.

3. The hydraulic control system for the servo-driven cylinder according to claim 1, characterized in that, The gear and rack cylinder converts the rotary motion of the servo motor into the linear reciprocating motion of the cylinder rod, thereby generating pressurized oil to drive the hydraulic cylinder to lift and lower.

4. The hydraulic control system for the servo-driven cylinder according to claim 1, characterized in that, Each minimum closed control unit works independently to achieve the lifting or lowering action of a single cylinder. Through closed-loop control, the lifting speed, output thrust or lowering speed, and return resistance of the hydraulic cylinder are precisely controlled.

5. The hydraulic control system for the servo-driven cylinder according to claim 1, characterized in that, Multiple minimum closed control units work together, and the closed-loop control of each unit is integrated into a large closed-loop control system to realize the motion control of multi-cylinder synchronous rise, differential rise, different thrust output or synchronous descent, differential descent, different resistance output.

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