CN110219843B - Pump-free hydraulic loading and positioning device - Google Patents

Pump-free hydraulic loading and positioning device Download PDF

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Publication number
CN110219843B
CN110219843B CN201910390819.6A CN201910390819A CN110219843B CN 110219843 B CN110219843 B CN 110219843B CN 201910390819 A CN201910390819 A CN 201910390819A CN 110219843 B CN110219843 B CN 110219843B
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China
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hydraulic
pressure
cylinder
cavity
loading
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CN110219843A (en
Inventor
吴金波
于文超
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Huazhong University of Science and Technology
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Huazhong University of Science and Technology
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/16Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B15/00Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
    • F15B15/08Characterised by the construction of the motor unit
    • F15B15/14Characterised by the construction of the motor unit of the straight-cylinder type
    • F15B15/1423Component parts; Constructional details
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B15/00Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
    • F15B15/20Other details, e.g. assembly with regulating devices
    • F15B15/28Means for indicating the position, e.g. end of stroke
    • F15B15/2815Position sensing, i.e. means for continuous measurement of position, e.g. LVDT

Abstract

The invention discloses a pumpless hydraulic loading and positioning device, and belongs to the field of hydraulic loading equipment. The device includes: the linear driver, the loading hydraulic cylinder, the pressure bearing cylinder, the backspacing mechanism and the processor; the output end of the linear driver is provided with a piston push rod; the loading hydraulic cylinder comprises a cylinder body, a piston rod and a displacement sensor; the pressure bearing cylinder is provided with an oil storage chamber, one end of the oil storage chamber is provided with a piston hole for a piston push rod of the linear driver to enter, and the other end of the oil storage chamber is communicated with a high-pressure cavity of the loading hydraulic cylinder through a first hydraulic pipeline; the backspacing mechanism comprises a gas-liquid pressure conversion cylinder and a gas source, and a hydraulic cavity of the gas-liquid pressure conversion cylinder is connected with a low-pressure cavity of the loading hydraulic cylinder through a second hydraulic pipeline; the air pressure cavity of the air-liquid pressure conversion cylinder is connected with an air pressure source; the processor is connected with the displacement sensor and the linear driver and used for carrying out closed-loop control on the displacement of the piston rod. The invention does not need a hydraulic pump station, reduces the energy loss of a loading system, avoids the noise of the hydraulic pump station and can accurately position the piston rod.

Description

Pump-free hydraulic loading and positioning device
Technical Field
The invention belongs to the field of hydraulic loading equipment, and particularly relates to a pumpless hydraulic loading and positioning device which is particularly suitable for the situation that the displacement of a piston of a loading hydraulic cylinder has high precision requirement and can work in a loading mode and a positioning mode.
Background
The hydraulic loading device can complete load simulation and performance evaluation of key bearing parts (such as a ship main propulsion shafting, a steering engine and the like) of large equipment under experimental conditions. The method has important significance for optimizing structural design, saving research and development time, reducing experiment cost and improving equipment reliability.
The traditional hydraulic loading device mainly adopts a valve-controlled hydraulic cylinder as an actuating element, and changes the oil pressure in a loading hydraulic oil cylinder by adjusting the opening degree of a servo valve so as to obtain the loading force expected by the system. Due to the influence of the throttling loss of the hydraulic valve, the energy utilization rate of the loading device is low, the phenomenon of overheating of hydraulic oil is easy to occur, and the stability and the control precision of the system are reduced. In addition, many of them use a hydraulic power unit as a power source, and the retraction of the piston of the loading hydraulic cylinder is realized by controlling the opening and closing of a large number of electro-hydraulic servo valves. The noise generated by the hydraulic pump station used in the method can hinder the work of field operators, and meanwhile, the hydraulic pump station occupies a large space, so that the utilization efficiency of equipment is influenced.
Disclosure of Invention
Aiming at the defects or the improvement requirements of the prior art, the invention provides a pumpless hydraulic loading and positioning device, which aims to drive a loading cylinder to load by using a linear driver as a pressure source and drive the loading cylinder to retreat by using an air pressure source as the pressure source, thereby realizing the driving and the retreat of a loading cylinder piston under the condition of not using a hydraulic pump station, effectively reducing the energy loss of a loading system and avoiding the noise generated by the operation of the hydraulic pump station; meanwhile, displacement closed-loop control is performed through a displacement sensor, a processor and a linear driver, so that accurate positioning of the loading cylinder piston is realized, and control accuracy is improved.
To achieve the above object, according to one aspect of the present invention, there is provided a pumpless type hydraulic loading and positioning apparatus, comprising: the hydraulic system comprises a linear driver, a loading hydraulic cylinder, a pressure bearing cylinder, a first hydraulic pipeline, a second hydraulic pipeline, a backspacing mechanism and a processor;
the output end of the linear driver is provided with a piston push rod;
the loading hydraulic cylinder comprises a cylinder body, a piston rod and a displacement sensor, wherein the piston rod divides the cylinder body into a high-pressure cavity and a low-pressure cavity; the displacement sensor is used for measuring the position of the piston rod.
The pressure-bearing cylinder is provided with an oil storage chamber, one end of the oil storage chamber is provided with a piston hole for a piston push rod of the linear driver to enter, and the other end of the oil storage chamber is communicated with a high-pressure cavity of the loading hydraulic cylinder through a first hydraulic pipeline;
the backspacing mechanism comprises a gas-liquid pressure conversion cylinder and a gas pressure source; a gas-liquid pressure conversion piston is arranged in the gas-liquid pressure conversion cylinder and divides the gas-liquid pressure conversion cylinder into a hydraulic cavity and a gas-pressure cavity; the hydraulic cavity of the gas-liquid pressure conversion cylinder is connected with the low-pressure cavity of the loading hydraulic cylinder through a second hydraulic pipeline; the air pressure cavity of the air-liquid pressure conversion cylinder is connected with an air pressure source;
the processor is connected with the displacement sensor and the linear driver so as to carry out closed-loop control on the displacement of the piston rod according to the displacement signal fed back by the displacement sensor.
Further, the sectional area of the hydraulic chamber of the gas-liquid pressure conversion cylinder is not larger than that of the pneumatic chamber.
Further, the sectional area of the hydraulic chamber is smaller than that of the pneumatic chamber; the gas-liquid pressure conversion piston comprises a hydraulic cavity plug body and a pressure cavity plug body which are fixedly connected with each other, the hydraulic cavity plug body is positioned in the hydraulic cavity, and the pressure cavity plug body is positioned in the pressure cavity; the cross section shape and size of the hydraulic cavity plug body are the same as those of the hydraulic cavity, and the cross section shape and size of the pneumatic cavity plug body are the same as those of the pneumatic cavity.
Furthermore, the hydraulic loading device comprises a plurality of loading hydraulic cylinders, a first hydraulic pipeline and a second hydraulic pipeline which are equal in number and correspond to one another one by one; and each loading hydraulic cylinder is connected in parallel between the pressure bearing cylinder and the gas-liquid pressure conversion cylinder through a first hydraulic pipeline and a second hydraulic pipeline which respectively correspond to the loading hydraulic cylinders.
Furthermore, each first hydraulic pipeline is provided with a pressure gauge, a first stop valve and a pressure sensor; the processor is connected with the pressure sensor to perform closed-loop control on the pressure of the first hydraulic pipeline according to the pressure signal fed back by the pressure sensor.
Furthermore, each first hydraulic pipeline is converged into a first hydraulic main pipe and is connected with the oil storage chamber through the first hydraulic main pipe; each second hydraulic pipeline is converged into a second hydraulic main pipe and is connected with the hydraulic cavity through the second hydraulic main pipe; the first hydraulic main pipe and the second hydraulic main pipe are respectively provided with a pressure gauge, and the second hydraulic main pipe is also provided with a second stop valve.
Further, the oil storage cylinder is characterized by further comprising an oil storage cylinder, and the oil storage cylinder is connected with an oil inlet of the pressure bearing cylinder.
Further, an oil outlet of the pressure bearing cylinder is provided with an overflow valve.
The invention also aims to drive the loading cylinder to load by using the linear driver as a pressure source and drive the loading cylinder to retreat by using the air pressure source as the pressure source, thereby realizing the driving and the retreat of the loading cylinder piston under the condition of not using a hydraulic pump station, effectively reducing the energy loss of a loading system and avoiding the noise generated by the operation of the hydraulic pump station.
In order to achieve the above object, according to another aspect of the present invention, there is provided a pump-less type hydraulic loading apparatus including: the hydraulic system comprises a linear driver, a loading hydraulic cylinder, a pressure bearing cylinder, a first hydraulic pipeline, a second hydraulic pipeline and a backspacing mechanism;
the output end of the linear driver is provided with a piston push rod;
the loading hydraulic cylinder comprises a cylinder body and a piston rod, and the cylinder body is divided into a high-pressure cavity and a low-pressure cavity by the piston rod;
the pressure-bearing cylinder is provided with an oil storage chamber, one end of the oil storage chamber is provided with a piston hole for a piston push rod of the linear driver to enter, and the other end of the oil storage chamber is communicated with a high-pressure cavity of the loading hydraulic cylinder through a first hydraulic pipeline;
the backspacing mechanism comprises a gas-liquid pressure conversion cylinder and a gas pressure source; a gas-liquid pressure conversion piston is arranged in the gas-liquid pressure conversion cylinder and divides the gas-liquid pressure conversion cylinder into a hydraulic cavity and a gas-pressure cavity; the hydraulic cavity of the gas-liquid pressure conversion cylinder is connected with the low-pressure cavity of the loading hydraulic cylinder through a second hydraulic pipeline; the air pressure cavity of the air-liquid pressure conversion cylinder is connected with an air pressure source.
Further, the sectional area of a hydraulic cavity of the gas-liquid pressure conversion cylinder is not larger than that of the air pressure cavity; wherein, when the sectional area of the hydraulic pressure cavity is smaller than that of the air pressure cavity:
the gas-liquid pressure conversion piston comprises a hydraulic cavity plug body and a pressure cavity plug body which are fixedly connected with each other, the hydraulic cavity plug body is positioned in the hydraulic cavity, and the pressure cavity plug body is positioned in the pressure cavity; the cross section shape and size of the hydraulic cavity plug body are the same as those of the hydraulic cavity, and the cross section shape and size of the pneumatic cavity plug body are the same as those of the pneumatic cavity.
In general, compared with the prior art, the above technical solution contemplated by the present invention can obtain the following beneficial effects:
1) the linear driver and the pressure-bearing cylinder are used as pressure amplification elements to drive the loading hydraulic cylinder to move, and meanwhile, the air pressure source is used for driving the loading hydraulic cylinder to reset, so that the problem that the traditional valve control electro-hydraulic loading device such as a hydraulic pump station is easy to generate noise is solved; a displacement closed-loop feedback control module is formed by the processor, the displacement sensor and the linear driving device, and the displacement of a piston push rod of the linear driving device is adjusted in real time by using data fed back by the displacement sensor, so that the displacement of the piston of the loading hydraulic cylinder is adjusted in real time and accurately positioned, and the high-reliability hydraulic loading device has high reliability.
2) Because the hydraulic circuit of the invention has almost no throttling loss, the loss in the energy transfer process mainly comes from mechanical transmission, and compared with the traditional valve control electro-hydraulic loading device, the hydraulic circuit has higher energy efficiency;
3) the retraction mechanism of the invention utilizes the compressibility of gas, and can be freely compressed when the loading hydraulic cylinder executes the loading work without interfering the normal operation; when the loading device needs to be reset, the energy stored due to gas compression can be directly utilized to push the loading hydraulic cylinder to reset, so that a hydraulic pump station is not needed, energy can be saved, and the space utilization rate of the loading device is improved;
4) the invention can support the parallel connection of the additional hydraulic cylinders, realizes the access of different loading hydraulic cylinders to the oil circuit by controlling the opening and closing of each first stop valve, can independently control or parallelly control the parallel loading hydraulic cylinders, and has flexible operation;
5) the invention can form a pressure closed loop feedback control mechanism by the processor, the pressure sensor and the linear driving device, and adjust the displacement of the piston push rod of the linear driving device in real time by utilizing the data fed back by the pressure sensor, thereby realizing the real-time adjustment and the accurate control of the loading force and having extremely high reliability.
Drawings
FIG. 1 is a system schematic of a pumpless hydraulic loading unit in accordance with a preferred embodiment of the present invention;
FIG. 2 is a schematic view of the linear actuator of FIG. 1 coupled to a pressure containing cylinder;
FIG. 3 is a schematic cross-sectional view of the pressure-containing cylinder of FIG. 1;
FIG. 4 is a schematic cross-sectional view of the loading cylinder of FIG. 1;
FIG. 5 is a schematic cross-sectional view of the gas-liquid pressure conversion cylinder of FIG. 1;
fig. 6 is a schematic sectional view of a gas-liquid pressure conversion cylinder according to a second embodiment of the present invention.
The same reference numbers will be used throughout the drawings to refer to the same or like elements or structures, wherein:
1-a linear driver, 2-an oil storage cylinder, 3-a pressure bearing cylinder, 4-a pressure gauge, 5-a first stop valve, 6-a pressure sensor, 7-a displacement sensor, 8-a loading hydraulic cylinder, 9-a backspacing mechanism, 10-a gas-liquid pressure conversion cylinder, 11-a gas pressure source, 12-a third stop valve, 13-an overflow valve, 14-an oil injection control valve bank, 15-an oil outlet of the pressure bearing cylinder, 16-a front end cover of the pressure bearing cylinder, 17-an oil storage chamber, 18-a rear end cover of the pressure bearing cylinder, 19-a piston push rod, 20-an electric cylinder, 21-a speed reducer, 22-a servo motor, 23-a shaft seal block, 24-an oil inlet, 25-an overflow port joint, 26-an oil outlet joint, 27-a high pressure cavity and 28-a piston rod, 29-a low-pressure cavity, 30-a hydraulic cavity, 31-a gas-liquid pressure conversion piston, 32-a gas pressure cavity, 33-a first hydraulic pipeline, 34-a second hydraulic pipeline and 35-a second stop valve.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The principle of the invention is that the pressure inside the container is regulated by forcibly changing the volume of the hydraulic oil in the closed container. The present invention uses the inverse relation between the liquid pressure and the liquid volume to achieve the loading purpose. The specific method comprises the following steps: a piston push rod 19 of the linear driver 1 enters the pressure bearing cylinder 3 through a sealing ring, the volume of closed oil in the pressure bearing cylinder 3 is changed by means of the extension and contraction of the piston push rod 19, expected loading pressure is generated according to the inverse proportion relation of oil pressure and volume, and a piston rod 28 of the loading hydraulic cylinder 8 is pushed to output a specified loading force.
As shown in fig. 1, the pumpless hydraulic loading apparatus according to the preferred embodiment of the present invention includes: the hydraulic control system comprises a linear driver 1, an oil storage cylinder 2, a pressure-bearing cylinder 3, a pressure gauge 4, a stop valve 5, a pressure sensor 6, a displacement sensor 7, a loading hydraulic cylinder 8, a backspacing mechanism 9, a gas-liquid pressure conversion cylinder 10, a gas pressure source 11, a third stop valve 12, an overflow valve 13, an oil injection control valve group 14, a first hydraulic pipeline 33, a second hydraulic pipeline 34 and a second stop valve 35.
Wherein, linear actuator 1 connects and bears a pressure section of thick bamboo 3, holds hydro-cylinder 2 and is used for leading 3 oiling to bearing through the oiling pipeline, is equipped with third stop valve 12 on the oiling pipeline. The overflow valve 13 is connected with the pressure bearing cylinder 3 and the oil storage cylinder 2, the oil storage cylinder 2 is filled with oil under the drive of gas, the oil filling control valve group 14 comprises two electromagnetic valves and a manual valve and is used for electrically or manually controlling the gas to apply pressure to the piston of the oil storage cylinder 2 to realize oil filling, the gas source of the oil storage cylinder 2 is omitted in the drawing, and a conventional pressurized gas source can be used. Two ends of the loading hydraulic cylinder 8 are respectively connected with the pressure bearing cylinder 3 and the left end of the retraction mechanism 9 through a first hydraulic pipeline 33 and a second hydraulic pipeline 34. The right end of the retraction mechanism 9 is connected to an air pressure source 11.
Preferably, the gas pressure source 11 may be an industrial gas cylinder, an ideal gas source, or an accumulator, so as to provide both a stable gas pressure and an energy storage using gas compression characteristics during loading. The air supply mode similar to the air storage cylinder 2 can be directly adopted, and air supply is directly carried out during resetting.
Referring to fig. 1 to 5, the linear actuator 1 of the present embodiment includes a piston rod 19, an electric cylinder 20, a reducer 21 and a servo motor 22. The piston push rod 19 is a built-in part of the electric cylinder 20, and the electric cylinder 20 can be directly purchased from an existing product. The use of the servomotor 22 allows precise control of the feed of the piston pusher 19 and thus of the loading force of the hydraulic and loading cylinders 8 and of the position of the piston rod 28. In other embodiments, the piston rod 19 may be mounted on any linear feed mechanism for driving, for example, a mover of a ball screw, and may be configured to linearly reciprocate to pressurize and depressurize the pressure receiving cylinder 3 without limitation. The loading cylinder 8 includes a cylinder body and a piston rod 28, and the piston rod 28 divides the cylinder body into a high pressure chamber 27 and a low pressure chamber 29, as shown in fig. 4.
The pressure-bearing cylinder 3 is provided with an oil storage chamber 17, one end of the oil storage chamber 17 is provided with a piston hole for a piston push rod 19 of the linear driver 1 to enter, and the piston push rod 19 is hermetically connected with a rear end cover 18 of the pressure-bearing cylinder in a shaft seal mode through a shaft seal block 23 and can freely reciprocate in the axial direction. The other end of the oil reservoir chamber 17 communicates with the high-pressure chamber 27 of the charging cylinder 8 through a first hydraulic line 33. The pressure-bearing cylinder 3 also comprises a pressure-bearing cylinder oil outlet 15, a pressure-bearing cylinder front end cover 16, an oil inlet 24, an overflow port joint 25 and an oil outlet joint 26. The pressure-bearing cylinder oil outlet 15 is connected with a first hydraulic pipeline 33 through an oil outlet joint 26 and is connected with the overflow valve 13 through an overflow port joint 25. The oil storage chamber 17 is connected with the oil inlet pipeline and the oil storage cylinder 2 through an oil inlet 24.
The retraction mechanism 9 includes a gas-liquid pressure conversion cylinder 10 and a pneumatic pressure source 11. The gas-liquid pressure conversion cylinder 10 is provided therein with a gas-liquid pressure conversion piston 31, and the gas-liquid pressure conversion piston 31 divides the gas-liquid pressure conversion cylinder 11 into a hydraulic chamber 30 and a pressure chamber 32. The hydraulic chamber 30 of the gas-liquid pressure conversion cylinder 10 is connected to the low-pressure chamber 29 of the charging hydraulic cylinder 8 through a second hydraulic line 34. The pneumatic chamber 32 of the gas-liquid pressure conversion cylinder 10 is connected to a pneumatic pressure source 11, and the pneumatic pressure source 11 is used for providing stable pneumatic pressure.
Preferably, in order to increase the pressure in the hydraulic chamber 30 so that a large restoring force can be provided by the pneumatic pressure source 11 having a small pressure, the sectional area of the hydraulic chamber 30 is smaller than that of the pneumatic chamber 32. Specifically, as shown in fig. 5, the gas-liquid pressure conversion piston 31 includes a hydraulic chamber plug body and a pressure chamber plug body that are fixedly connected to each other, the hydraulic chamber plug body is located in the hydraulic chamber 30, and the pressure chamber plug body is located in the pressure chamber 32. The cross-sectional shape and size of the hydraulic chamber plug are the same as those of the hydraulic chamber 30, and the cross-sectional shape and size of the pneumatic chamber plug are the same as those of the pneumatic chamber 32. The ratio of the hydraulic chamber 30 to the pneumatic chamber 32 determines the pressure conversion factor.
Preferably, the present embodiment adopts a scheme of multi-cylinder parallel connection and independent control. Specifically, as shown in fig. 1, the present embodiment is provided with a plurality of loading hydraulic cylinders 8, first hydraulic lines 33, and second hydraulic lines 34, which are equal in number and correspond one to one; each of the loading cylinders 8 is connected in parallel between the pressure-receiving cylinder 3 and the gas-liquid pressure conversion cylinder 10 via a corresponding first hydraulic line 33 and a corresponding second hydraulic line 34. Each first hydraulic line 33 is provided with a pressure gauge 4, a first stop valve 5 and a pressure sensor 6. Each first hydraulic line 33 merges into the first hydraulic manifold and is connected to the oil reservoir 17 via the first hydraulic manifold; each second hydraulic line 34 is converged into a second hydraulic manifold and is connected to the hydraulic chamber 30 through the second hydraulic manifold; be equipped with manometer 4 on first hydraulic pressure house steward and the second hydraulic pressure house steward respectively, still be equipped with second stop valve 35 on the second hydraulic pressure house steward. Each loading hydraulic cylinder 8 is provided with a displacement sensor 7 for measuring the position of the piston rod 8. The processor (not shown) is connected with the displacement sensor 7 and the linear driver 1 to form a displacement closed-loop feedback control mechanism, and is used for accurately controlling the feeding amount of the piston push rod 19 in the linear driver 1, so that the position of the piston rod 28 of the loading hydraulic cylinder 8 is accurately controlled, and accurate positioning is realized. The processor (not shown) is connected with the pressure sensor 6 and the linear driver 1 to form a pressure closed loop feedback control mechanism for accurately controlling the feeding amount of the piston push rod 19 in the linear driver 1, so as to accurately control the loading force of the loading hydraulic cylinder 8.
In the following, the working process and working principle of this embodiment are described by taking the used air pressure source 11 as an industrial air cylinder as an example:
before loading, oil is injected into the pressure-bearing cylinder 3. And opening a manual valve or an electromagnetic valve of the oil injection control valve group 14 and a third stop valve 12 on the oil injection pipeline, and pushing a piston in the oil storage cylinder 2 by using air pressure to inject oil into an oil storage chamber 17 of the pressure bearing cylinder 3. When the loading pressure of the pressure bearing cylinder 3 is too high, the overflow valve 13 opens the overflow valve to be connected with the oil storage cylinder 2, so that the overload condition of the linear driver 1 is prevented. After the oil injection is finished, the third stop valve 12 is closed.
When loading is carried out, according to actual working requirements, the second stop valve 35 and any first stop valve 5 are opened, then the servo motor 22 is started to control the piston push rod 19 of the electric cylinder 1 to generate specified displacement, so that the oil volume in the oil storage chamber 17 of the pressure bearing cylinder 3 is forcibly changed, and further the internal pressure of the pressure bearing cylinder is changed. During loading, the servo motor 22 rotates forwards, the piston push rod 19 extends, high-pressure oil in the pressure-bearing cylinder 3 is injected into the corresponding high-pressure cavity 27 of the loading hydraulic cylinder 8, and the piston rod 28 is pushed to generate corresponding loading force. At this time, the gas in the gas pressure chamber 32 of the gas-liquid pressure conversion cylinder 10 is compressed and retracted into the industrial gas cylinder. Further, the movement of the piston rod 28 can be made more smooth due to the reaction force of the gas compression.
Preferably, the invention can work in both the positioning mode and the loading mode:
for the positioning working mode, the control quantity input into the electric cylinder 1 can be corrected through the feedback signal of the displacement sensor 7 in the loading process, so that the accurate control of the displacement of the piston rod 28 of the loading hydraulic cylinder 8 is realized;
for the loading working mode, the control quantity input into the electric cylinder 1 can be corrected through the feedback signal of the pressure sensor 6 in the loading process, so that the accurate control of the loading force of the piston rod 28 of the loading hydraulic cylinder 8 is realized.
The invention can keep the loading pressure unchanged after reaching a certain degree. Specifically, the servo motor 22 is turned off or suspended and the first stop valve 5 and the second stop valve 35 are closed after a predetermined force is applied. At this time, the electric cylinder 1 has no input, the piston rod 19 does not act, and the oil in the high pressure chamber 27 of the loading hydraulic cylinder 8 is isolated from the outside, and a constant pressure is maintained.
After the loading is finished, the retraction of the piston rod of the loading hydraulic cylinder 8 is realized by utilizing the principle of gas compressibility. Specifically, after the loading is finished, the first stop valve 5 and the second stop valve 35 are opened, the processor controls the servo motor 22 to rotate reversely, the piston push rod 19 of the electric cylinder 1 is driven to retreat, and the oil liquid in the inner cavity of the pressure-bearing cylinder 3 recovers the initial pressure before the loading. Meanwhile, the hydraulic cavity 30 of the gas-liquid pressure conversion cylinder 10 is decompressed, the gas in the industrial gas cylinder is refilled into the gas pressure cavity of the gas-liquid pressure conversion cylinder 10, the gas-liquid pressure conversion piston 31 is pushed to recover the initial position, the oil liquid in the hydraulic cavity 30 is synchronously pushed to be injected into the low pressure cavity 29 of the loading hydraulic cylinder 8 through the second hydraulic pipeline 34, and the piston push rod 19 of the loading hydraulic cylinder 8 is pushed to retreat to the initial position.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (10)

1. A pumpless hydraulic loading and positioning device, comprising: the hydraulic control system comprises a linear driver (1), a loading hydraulic cylinder (8), a pressure bearing cylinder (3), a first hydraulic pipeline (33), a second hydraulic pipeline (34), a backspacing mechanism (9) and a processor;
the output end of the linear driver (1) is provided with a piston push rod (19);
the loading hydraulic cylinder (8) comprises a cylinder body, a piston rod (28) and a displacement sensor (7), wherein the cylinder body is divided into a high-pressure cavity (27) and a low-pressure cavity (29) by the piston rod (28); the displacement sensor (7) is used for measuring the position of the piston rod (28);
the pressure-bearing cylinder (3) is provided with an oil storage chamber (17), one end of the oil storage chamber (17) is provided with a piston hole for a piston push rod (19) of the linear driver (1) to enter, and the other end of the oil storage chamber is communicated with a high-pressure cavity (27) of the loading hydraulic cylinder (8) through a first hydraulic pipeline (33);
the retraction mechanism (9) comprises a gas-liquid pressure conversion cylinder (10) and a gas pressure source (11); a gas-liquid pressure conversion piston (31) is arranged in the gas-liquid pressure conversion cylinder (10), and the gas-liquid pressure conversion piston (31) divides the gas-liquid pressure conversion cylinder (10) into a hydraulic cavity (30) and a pneumatic cavity (32); a hydraulic cavity (30) of the gas-liquid pressure conversion cylinder (10) is connected with a low-pressure cavity (29) of the loading hydraulic cylinder (8) through a second hydraulic pipeline (34); the air pressure cavity (32) of the air-liquid pressure conversion cylinder (10) is connected with an air pressure source (11);
the processor is connected with the displacement sensor (7) and the linear driver (1) to carry out closed-loop control on the displacement of the piston rod (28) according to the displacement signal fed back by the displacement sensor (7).
2. A pumpless hydraulic loading and positioning device as defined in claim 1, wherein a sectional area of the hydraulic chamber (30) of the gas-liquid pressure conversion cylinder (10) is not larger than a sectional area of the pneumatic chamber (32).
3. A pumpless hydraulic loading and positioning device as defined in claim 2, wherein the hydraulic chamber (30) has a smaller cross-sectional area than the pneumatic chamber (32); the gas-liquid pressure conversion piston (31) comprises a hydraulic cavity plug body and a pressure cavity plug body which are fixedly connected with each other, the hydraulic cavity plug body is positioned in the hydraulic cavity (30), and the pressure cavity plug body is positioned in the pressure cavity (32); the cross section shape and size of the hydraulic cavity plug body are the same as the cross section of the hydraulic cavity (30), and the cross section shape and size of the pneumatic cavity plug body are the same as the cross section of the pneumatic cavity (32).
4. A pumpless hydraulic loading and positioning device as defined in any one of claims 1 to 3, comprising a plurality of loading cylinders (8), first hydraulic lines (33) and second hydraulic lines (34) in equal numbers and in one-to-one correspondence; each loading hydraulic cylinder (8) is connected in parallel between the pressure bearing cylinder (3) and the gas-liquid pressure conversion cylinder (10) through a first hydraulic pipeline (33) and a second hydraulic pipeline (34) which correspond to each other.
5. A hydraulic loading and positioning device of the pumpless type, as defined in claim 4, wherein each of the first hydraulic lines (33) is provided with a pressure gauge (4), a first shut-off valve (5) and a pressure sensor (6); the processor is connected with the pressure sensor (6) to carry out closed-loop control on the pressure of the first hydraulic pipeline (33) according to the pressure signal fed back by the pressure sensor (6).
6. A pumpless hydraulic loading and positioning device as defined in claim 5, wherein each of the first hydraulic lines (33) opens into a first hydraulic manifold and is connected to the oil reservoir (17) via the first hydraulic manifold; each second hydraulic pipeline (34) is converged into a second hydraulic main pipe and is connected with the hydraulic cavity (30) through the second hydraulic main pipe; be equipped with manometer (4) respectively on first hydraulic pressure house steward and the second hydraulic pressure house steward, still be equipped with second stop valve (35) on the second hydraulic pressure house steward.
7. The pumpless hydraulic loading and positioning device as claimed in any one of claims 1 to 3, further comprising an oil storage cylinder (2), wherein the oil storage cylinder (2) is connected to an oil inlet of the pressure bearing cylinder (3).
8. A pumpless hydraulic loading and positioning device as defined in any one of claims 1 to 3, wherein an oil outlet of the pressure-bearing cylinder (3) is provided with an overflow valve (13).
9. A pumpless hydraulic loading unit, comprising: the hydraulic control system comprises a linear driver (1), a loading hydraulic cylinder (8), a pressure bearing cylinder (3), a first hydraulic pipeline (33), a second hydraulic pipeline (34) and a retraction mechanism (9);
the output end of the linear driver (1) is provided with a piston push rod (19);
the loading hydraulic cylinder (8) comprises a cylinder body and a piston rod (28), and the piston rod (28) divides the cylinder body into a high-pressure cavity (27) and a low-pressure cavity (29);
the pressure-bearing cylinder (3) is provided with an oil storage chamber (17), one end of the oil storage chamber (17) is provided with a piston hole for a piston push rod (19) of the linear driver (1) to enter, and the other end of the oil storage chamber is communicated with a high-pressure cavity (27) of the loading hydraulic cylinder (8) through a first hydraulic pipeline (33);
the retraction mechanism (9) comprises a gas-liquid pressure conversion cylinder (10) and a gas pressure source (11); a gas-liquid pressure conversion piston (31) is arranged in the gas-liquid pressure conversion cylinder (10), and the gas-liquid pressure conversion piston (31) divides the gas-liquid pressure conversion cylinder (10) into a hydraulic cavity (30) and a pneumatic cavity (32); a hydraulic cavity (30) of the gas-liquid pressure conversion cylinder (10) is connected with a low-pressure cavity (29) of the loading hydraulic cylinder (8) through a second hydraulic pipeline (34); the air pressure cavity (32) of the air-liquid pressure conversion cylinder (10) is connected with an air pressure source (11).
10. A pumpless hydraulic loading apparatus as set forth in claim 9, wherein a sectional area of the hydraulic chamber (30) of the gas-liquid pressure conversion cylinder (10) is not larger than a sectional area of the pneumatic chamber (32); wherein, when the sectional area of the hydraulic chamber (30) is smaller than the sectional area of the pneumatic chamber (32):
the gas-liquid pressure conversion piston (31) comprises a hydraulic cavity plug body and a pressure cavity plug body which are fixedly connected with each other, the hydraulic cavity plug body is positioned in the hydraulic cavity (30), and the pressure cavity plug body is positioned in the pressure cavity (32); the cross section shape and size of the hydraulic cavity plug body are the same as the cross section of the hydraulic cavity (30), and the cross section shape and size of the pneumatic cavity plug body are the same as the cross section of the pneumatic cavity (32).
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CN1821589A (en) * 2006-03-16 2006-08-23 靖江宝骊叉车有限公司 Double action cylinder loading test device
CN201225342Y (en) * 2008-07-14 2009-04-22 上海建设路桥机械设备有限公司 Hydraulic device
CN201568393U (en) * 2009-04-25 2010-09-01 孙家茂 Hydraulic system without pump
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