A high-precision digital hydraulic cylinder

Abstract

The application provides a high-precision digital hydraulic cylinder and relates to the technical field of digital hydraulic cylinders.The high-precision digital hydraulic cylinder comprises a cylinder body, a piston, a piston rod, a screw rod base, a feedback screw rod, a first encoder, an oil way valve base, a hydraulic oil supply unit, a servo motor and a controller.The high-precision digital hydraulic cylinder has low requirements for the hydraulic oil supply unit, and the hydraulic oil supply unit only needs to provide a hydraulic oil with a set pressure, the servo motor drives a gear set to rotate according to the number of pulses, the hydraulic oil is quantitatively pressed into the rod cavity or the rodless cavity of the cylinder body, the moving speed or displacement of the piston of the cylinder is accurately controlled, the moving speed or displacement of the piston is directly fed back through a screw pair, and real-time and accurate closed-loop control of the moving speed or displacement of the piston is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of digital hydraulic cylinders, in particular to a high-precision digital hydraulic cylinder. BACKGROUND

[0002] With the development of intelligent and unmanned technology in mines, intelligent and unmanned technology has become a development trend of future mine equipment, and the control accuracy of control equipment is required to be higher and higher. The load of mine equipment is large, and its actuator is mostly a hydraulic cylinder. The hydraulic cylinder is a key equipment for intelligent and accurate control. The ordinary engineering cylinder and servo cylinder on the market have been difficult to meet the requirements of customers. The ordinary engineering cylinder has problems such as insufficient positioning accuracy, lagging start-stop feedback speed, and being greatly affected by the environment. The servo cylinder system is relatively complex, and the sensor has poor anti-interference ability. In addition, the digital cylinder on the market currently uses proportional valves or digital valves, which are difficult to process, complex to install and debug, require high technical level of on-site personnel, and cannot be repaired and debugged after failure on site. SUMMARY

[0003] The purpose of the present application is to provide a high-precision digital hydraulic cylinder to realize accurate control of the operation of the hydraulic cylinder.

[0004] In order to achieve the above purpose, the technical solution adopted by the present application is as follows:

[0005] A high-precision digital hydraulic cylinder, comprising a cylinder body, a piston, a piston rod, a screw rod seat, a feedback screw rod, a first encoder, an oil way valve seat, a hydraulic oil supply unit, a servo motor and a controller.

[0006] The inside of the cylinder body is provided with the piston, the piston can move linearly reciprocatingly relative to the cylinder body, and one end of the piston rod is assembled and connected to the piston.

[0007] One end of the piston or the piston rod is provided with the screw rod seat, the feedback screw rod is threadedly connected with the screw rod seat, and one end of the feedback screw rod is rotationally connected with the cylinder body.

[0008] The screw rod seat can move linearly reciprocatingly relative to the feedback screw rod, and at the same time, the screw rod seat can drive the feedback screw rod to rotate around its axis.

[0009] The first encoder is used for sensing the angular displacement signal of the feedback screw rod.

[0010] The inside of the oil way valve seat is provided with an oil cavity, the oil way valve seat is provided with an oil inlet nozzle, a first oil outlet oil way and a second oil outlet oil way which are in communication with the oil cavity.

[0011] The hydraulic oil supply unit is connected to the oil inlet nozzle, and the hydraulic oil supply unit injects hydraulic oil with a set pressure into the oil inlet nozzle, and the first oil outlet oil path and the second oil outlet oil path are respectively connected to the rod cavity and the rodless cavity of the cylinder body;

[0012] The gear set is rotatably connected inside the oil cavity of the oil path valve seat, and the output rotating shaft of the servo motor is power-connected to the gear set;

[0013] The output rotating shaft of the servo motor rotates forward or reversely to selectively press the hydraulic oil entering the oil inlet nozzle into the first oil outlet oil path or the second oil outlet oil path through the gear set;

[0014] The rotating speed of the output rotating shaft of the servo motor is proportional to the oil amount pressed into the first oil outlet oil path or the second oil outlet oil path;

[0015] The controller is respectively connected to the first encoder and the servo motor through signal cables, receives the angular displacement signals transmitted by the first encoder, and controls the rotating speed of the output rotating shaft of the servo motor.

[0016] Preferably, the gear set comprises a driving gear and a driven gear which are meshed with each other, the output rotating shaft of the servo motor is power-connected to the driving gear, the communication position of the oil inlet nozzle with the oil cavity is located on one side of the intermediate position of the driving gear and the driven gear, the communication position of the first oil outlet oil path with the oil cavity is located on the other side of the intermediate position of the driving gear and the driven gear, the communication position of the second oil outlet oil path with the oil cavity is located on the outside of the driving gear and / or the driven gear, the first oil outlet oil path is provided with a first hydraulic control valve group, the second oil outlet oil path is provided with a second hydraulic control valve group, the first oil outlet oil path is connected to the hydraulic control end of the second hydraulic control valve group through a first pilot oil path, and the second oil outlet oil path is connected to the hydraulic control end of the first hydraulic control valve group through a second pilot oil path; the hydraulic oil pressure of the first pilot oil path is raised to the set pressure to trigger the second hydraulic control valve group to shut off the second oil outlet oil path, and the hydraulic oil pressure of the second pilot oil path is raised to the set pressure to trigger the first hydraulic control valve group to shut off the first oil outlet oil path.

[0017] Preferably, the first oil outlet oil path is connected to the rod cavity of the cylinder body through a first oil supply pipeline, the first oil supply pipeline is provided with a first check valve, the second oil outlet oil path is connected to the rodless cavity of the cylinder body through a second oil supply pipeline, and the second oil supply pipeline is provided with a second check valve;

[0018] The first unloading pipeline is connected to the oil outlet side of the first check valve, the first unloading pipeline is provided with a third hydraulic control valve group, the second unloading pipeline is connected to the oil outlet side of the second check valve, and the second unloading pipeline is provided with a fourth hydraulic control valve group;

[0019] The first oil supply pipeline is connected with the hydraulic control end of the fourth hydraulic control valve group through the third pilot oil path on the oil inlet side of the first check valve, and the second oil supply pipeline is connected with the hydraulic control end of the third hydraulic control valve group through the fourth pilot oil path on the oil inlet side of the second check valve.

[0020] The hydraulic oil pressure of the third pilot oil path is raised to a set pressure to trigger the fourth hydraulic control valve group to open the second pressure relief pipeline, and the hydraulic oil pressure of the fourth pilot oil path is raised to a set pressure to trigger the third hydraulic control valve group to open the first pressure relief pipeline.

[0021] Preferably, the hydraulic oil supply unit comprises an oil pump, an oil suction pipeline, a hydraulic oil tank, a main oil supply pipeline, a third check valve, a third pressure relief pipeline and a safety valve.

[0022] The oil inlet end of the oil pump is connected with the hydraulic oil tank through the oil suction pipeline, the oil outlet end of the oil pump is connected with the oil inlet nozzle through the main oil supply pipeline, the third check valve is arranged on the main oil supply pipeline, the main oil supply pipeline is connected with the hydraulic oil tank through the third pressure relief pipeline on the oil outlet side of the third check valve, and the safety valve is arranged on the third pressure relief pipeline.

[0023] Preferably, the output rotating shaft of the servo motor is connected with the driving gear through a shaft coupling.

[0024] Preferably, the cylinder body is rotationally connected with a target rotating shaft, the target rotating shaft is provided with a first synchronous wheel at the tail end, one end of the feedback screw rod is provided with a second synchronous wheel, a synchronous belt is connected between the first synchronous wheel and the second synchronous wheel, and the first encoder senses the angular displacement signal of the target rotating shaft and further senses the angular displacement signal of the feedback screw rod.

[0025] Preferably, the second encoder is further connected with the controller through a signal cable, the second encoder is used for sensing the angular displacement signal of the output rotating shaft of the servo motor, and the controller receives the angular displacement signal transmitted by the second encoder.

[0026] Preferably, the inside of the piston rod is provided as a hollow cavity, and the feedback screw rod is located inside the hollow cavity.

[0027] Preferably, the oil way valve seat is arranged at the rear end of the cylinder body, the motor support is arranged on the oil way valve seat, and the servo motor is arranged on the motor support.

[0028] Preferably, the front end of the cylinder body is provided with an oil cylinder flange.

[0029] The beneficial technical effects of the present application are:

[0030] The high-precision digital hydraulic cylinder of the application has low requirement for the hydraulic oil supply unit, and the hydraulic oil supply unit only needs to provide hydraulic oil with a set pressure, and the gear set is driven to rotate by the servo motor according to the pulse number, so that the hydraulic oil is quantitatively pressed into the rod cavity or the rodless cavity of the cylinder body, so as to accurately control the moving speed or displacement of the piston of the cylinder, and the moving speed or displacement of the piston is directly fed back through the screw pair, so that the real-time and accurate closed-loop control of the moving speed or displacement of the piston is realized. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a perspective view of the high-precision digital hydraulic cylinder in the embodiment of the application Figure 1 ;

[0032] Figure 2 is a perspective view of the high-precision digital hydraulic cylinder in the embodiment of the application Figure 2 ;

[0033] Figure 3 is a sectional view of the high-precision digital hydraulic cylinder in the embodiment of the application;

[0034] Figure 4 is a perspective view of part of the structure of the high-precision digital hydraulic cylinder in the embodiment of the application;

[0035] Figure 5 is a hydraulic principle diagram of the high-precision digital hydraulic cylinder in the embodiment of the application;

[0036] Figure 6 is a structural schematic view of the oil way valve seat part in the high-precision digital hydraulic cylinder in the embodiment of the application. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and beneficial effects of the application clearer and more apparent, the application will be further described in detail below in combination with specific embodiments and with reference to the drawings. Some but not all of the embodiments of the application will be shown in the drawings. In fact, various embodiments of the application can be implemented in many different forms, and should not be interpreted as being limited to the embodiments described herein; on the contrary, these embodiments are provided to meet the applicable legal requirements.

[0038] In the description of the application, it should be noted that the terms "inner", "outer", "upper", "lower", "front", "rear" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0039] In the embodiment of the present application, a high-precision digital hydraulic cylinder is provided, please refer to Figures 1 to 6 as shown.

[0040] A high-precision digital hydraulic cylinder, comprising a cylinder body 11, a piston 12, a piston rod 13, a screw rod seat 14, a feedback screw rod 15, a first encoder 21, a second encoder 22, an oil way valve seat 3, a hydraulic oil supply unit, a servo motor 4 and a controller.

[0041] The front end of the cylinder body 11 is provided with a cylinder flange 110, so that the cylinder is assembled to the equipment through the cylinder flange 110.

[0042] The inside of the cylinder body 11 is provided with the piston 12, which can move linearly reciprocatingly relative to the cylinder body 11 under the push of the hydraulic oil, and one end of the piston rod 13 is assembled and connected to the piston 12. The front end of the cylinder body 11 is assembled with a front end cover 112, and the other end of the piston rod 13 penetrates through the front end cover 112, which is used for connecting a load, and the piston 12 moves linearly reciprocatingly to drive the load to move linearly reciprocatingly through the piston rod 13.

[0043] One end of the piston rod 13 is assembled with the screw rod seat 14, which is provided with a threaded hole, and the feedback screw rod 15 is provided with an external thread, and the feedback screw rod 15 is screwed with the threaded hole of the screw rod seat 14, and one end of the feedback screw rod 15 is rotatably connected to the cylinder body 11. Wherein, the rear end of the cylinder body 11 is assembled with a rear end cover 111, and one end of the feedback screw rod 15 is assembled and connected to the rear end cover 111 through a bearing 5.

[0044] The inside of the piston rod 13 is provided as a hollow cavity, and the feedback screw rod 15 is located inside the hollow cavity. A plug 131 is assembled at the end of the piston rod 13 in the hollow cavity to seal the hollow cavity.

[0045] The screw rod seat 14 can move linearly reciprocatingly with the piston rod 13, and the screw rod seat 14 can move linearly reciprocatingly relative to the feedback screw rod 15, and at the same time, the screw rod seat 14 can drive the feedback screw rod 15 to rotate around the axis of the feedback screw rod 15.

[0046] The first encoder 21 is used for sensing the angular displacement signal of the feedback screw rod 15. Wherein, the target rotating shaft 16 is rotatably connected to the oil way valve seat 3 on the cylinder body 11, and specifically, the two ends of the target rotating shaft 16 are assembled and connected to the oil way valve seat 3 through bearings 5.

[0047] The end of the target rotating shaft 16 is provided with a first synchronous pulley 171, one end of the feedback screw rod 15 is provided with a second synchronous pulley 172, and a synchronous belt 173 is connected between the first synchronous pulley 171 and the second synchronous pulley 172. The first encoder 21 is arranged on the oil way valve seat 3, and the first encoder 21 senses the angular displacement signal of the feedback screw rod 15 by sensing the angular displacement signal of the target rotating shaft 16.

[0048] The oil passage valve seat 3 is internally provided with an oil cavity 30, and the oil passage valve seat 3 is provided with an oil inlet nozzle 31, a first oil outlet oil passage 321 and a second oil outlet oil passage 322 which are in communication with the oil cavity 30.

[0049] The hydraulic oil supply unit is connected to the oil inlet nozzle 31, and the hydraulic oil supply unit injects hydraulic oil of a set pressure into the oil inlet nozzle 31, and the first oil outlet oil passage 321 and the second oil outlet oil passage 322 are respectively connected to the rod cavity and the rodless cavity of the cylinder body 11.

[0050] The oil cavity 30 of the oil passage valve seat 3 is rotatably connected with a gear set, and the output shaft of the servo motor 4 is power-connected to the gear set. The output shaft of the servo motor 4 rotates forward or reversely to selectively press the hydraulic oil entering the oil inlet nozzle 31 into the first oil outlet oil passage 321 or the second oil outlet oil passage 322 through the gear set.

[0051] The oil passage valve seat 3 is arranged at the rear end of the cylinder body 11, and the oil passage valve seat 3 is provided with a motor support 40, and the servo motor 4 is arranged on the motor support 40.

[0052] The rotation speed of the output shaft of the servo motor 4 is proportional to the amount of oil pressed into the first oil outlet oil passage 321 or the second oil outlet oil passage 322. In this way, the hydraulic oil is quantitatively pressed into the first oil outlet oil passage 321 or the second oil outlet oil passage 322 according to the rotation speed of the output shaft of the servo motor 4, so as to accurately drive the piston 12 to move linearly relative to the cylinder body 11.

[0053] The controller of the embodiment is a PLC controller, and the controller is connected to the first encoder 21 and the control end of the servo motor 4 through signal cables respectively. The controller receives the angular displacement signal uploaded by the first encoder 21, and controls the rotation speed of the output shaft of the servo motor 4. The rotation speed of the output shaft of the servo motor 4 includes start, stop, forward rotation, reverse rotation and different rotation speeds in forward or reverse directions. The angular displacement signal uploaded by the first encoder 21 is used to accurately feed back the current moving speed and displacement of the piston 12 relative to the cylinder body 11, and the rotation speed of the output shaft of the servo motor 4 is controlled by the controller to accurately drive the piston 12 to move linearly relative to the cylinder body 11.

[0054] The controller is also connected to the second encoder 22 through a signal cable, and the second encoder 22 is used to sense the angular displacement signal of the output shaft of the servo motor 4, and the controller receives the angular displacement signal uploaded by the second encoder 22. In this way, the actual rotation speed of the output shaft of the servo motor 4 is checked by the second encoder 22.

[0055] The gear set includes a driving gear 331 and a driven gear 332 that mesh with each other. The output shaft of the servo motor 4 is poweredly connected to the driving gear 331 via a coupling 41. The connection between the oil inlet 31 and the oil chamber 30 is located on one side of the middle position between the driving gear 331 and the driven gear 332. The connection between the first oil outlet 321 and the oil chamber 30 is located on the other side of the middle position between the driving gear 331 and the driven gear 332. The connection between one second oil outlet 322 and the oil chamber 30 is located outside the driving gear 331, and the connection between the other second oil outlet 322 and the oil chamber 30 is located outside the driven gear 332.

[0056] The first oil outlet passage 321 is equipped with a first hydraulic control valve assembly 341, and the second oil outlet passage 322 is equipped with a second hydraulic control valve assembly 342. The first oil outlet passage 321 is connected to the hydraulic control terminal of the second hydraulic control valve assembly 342 via a first pilot oil passage 351, and the second oil outlet passage 322 is connected to the hydraulic control terminal of the first hydraulic control valve assembly 341 via a second pilot oil passage 352. When the hydraulic oil pressure in the first pilot oil passage 351 is lower than the set pressure P1, the second hydraulic control valve assembly 342 opens the second oil outlet passage 322; when the hydraulic oil pressure in the first pilot oil passage 351 rises to the set pressure P1, the second hydraulic control valve assembly 342 is triggered to close the second oil outlet passage 322. When the hydraulic oil pressure in the second pilot oil circuit 352 is lower than the set pressure P2, the first hydraulic control valve group 341 opens the first oil outlet circuit 321; when the hydraulic oil pressure in the second pilot oil circuit 352 rises to the set pressure P2, the first hydraulic control valve group 341 is triggered to close the first oil outlet circuit 321.

[0057] like Figure 6 As shown, the drive gear 331 rotates clockwise, forcing the hydraulic oil entering the inlet 31 into the first outlet oil passage 321. The drive gear 331 also rotates counterclockwise, forcing the hydraulic oil entering the inlet 31 into the second outlet oil passage 322. Simultaneously, when hydraulic oil enters the first outlet oil passage 321, it also enters the first pilot oil passage 351, raising the hydraulic oil pressure in the first pilot oil passage 351 to a set pressure P1. Similarly, when hydraulic oil enters the second outlet oil passage 322, it also enters the second pilot oil passage 352, raising the hydraulic oil pressure in the second pilot oil passage 352 to a set pressure P2.

[0058] The first oil outlet passage 321 is connected to the rod chamber of the cylinder 11 via the first oil supply line 611, and a first check valve 621 is provided on the first oil supply line 611; the second oil outlet passage 322 is connected to the rodless chamber of the cylinder 11 via the second oil supply line 612, and a second check valve 622 is provided on the second oil supply line 612.

[0059] The first oil supply pipeline 611 is connected with the first pressure relief pipeline 631 at the oil outlet side of the first one-way valve 621, the first pressure relief pipeline 631 is connected with the hydraulic oil tank 73 through the oil return nozzle 633, and the first pressure relief pipeline 631 is provided with the third hydraulic control valve group 641; the second oil supply pipeline 612 is connected with the second pressure relief pipeline 632 at the oil outlet side of the second one-way valve 622, the second pressure relief pipeline 632 is connected with the hydraulic oil tank 73 through the oil return nozzle 633, and the second pressure relief pipeline 632 is provided with the fourth hydraulic control valve group 642.

[0060] The first oil supply pipeline 611 is connected with the first pressure relief pipeline 631 at the oil outlet side of the first one-way valve 621, the first pressure relief pipeline 631 is connected with the hydraulic oil tank 73 through the oil return nozzle 633, and the first pressure relief pipeline 631 is provided with the third hydraulic control valve group 641; the second oil supply pipeline 612 is connected with the second pressure relief pipeline 632 at the oil outlet side of the second one-way valve 622, the second pressure relief pipeline 632 is connected with the hydraulic oil tank 73 through the oil return nozzle 633, and the second pressure relief pipeline 632 is provided with the fourth hydraulic control valve group 642.

[0061] When the hydraulic oil pressure of the third pilot oil line 651 is lower than the set pressure P3, the fourth hydraulic control valve group 642 cuts off the second pressure relief pipeline 632; when the hydraulic oil pressure of the third pilot oil line 651 rises to the set pressure P3, the fourth hydraulic control valve group 642 is triggered to open the second pressure relief pipeline 632. When the hydraulic oil pressure of the fourth pilot oil line 652 is lower than the set pressure P4, the third hydraulic control valve group 641 cuts off the first pressure relief pipeline 631; when the hydraulic oil pressure of the fourth pilot oil line 652 rises to the set pressure P4, the third hydraulic control valve group 641 is triggered to open the first pressure relief pipeline 631.

[0062] In this way, when hydraulic oil is injected into the rod cavity of the cylinder 11 through the first oil supply pipeline 611, the hydraulic oil in the rodless cavity of the cylinder 11 is relieved through the second pressure relief pipeline 632; when hydraulic oil is injected into the rodless cavity of the cylinder 11 through the second oil supply pipeline 612, the hydraulic oil in the rod cavity of the cylinder 11 is relieved through the first pressure relief pipeline 631.

[0063] The hydraulic oil supply unit includes an oil pump 71, an oil suction pipeline 721, a hydraulic oil tank 73, a main oil supply pipeline 722, a third one-way valve 74, a third pressure relief pipeline 723, and a safety valve 75.

[0064] The oil inlet end of the oil pump 71 is connected with the hydraulic oil tank 73 through the oil suction pipeline 721, the oil outlet end of the oil pump 71 is connected with the oil inlet nozzle 31 through the main oil supply pipeline 722, the main oil supply pipeline 722 is provided with the third one-way valve 74, the main oil supply pipeline 722 is connected with the hydraulic oil tank 73 through the third pressure relief pipeline 723 at the oil outlet side of the third one-way valve 74, and the third pressure relief pipeline 723 is provided with the safety valve 75.

[0065] The oil pump 71 pressurizes the hydraulic oil in the hydraulic oil tank 73 into the main oil supply pipeline 722 through the oil suction pipeline 721, and when the oil pressure in the main oil supply pipeline 722 exceeds the set pressure, the hydraulic oil is relieved to the hydraulic oil tank 73 through the third pressure relief pipeline 723 and the safety valve 75.

[0066] An oil suction filter 76 is arranged on the oil suction pipeline 721 to filter the hydraulic oil entering the oil suction pipeline 721 through the oil suction filter 76.

[0067] An air filter 77 is connected to the air inlet of the hydraulic oil tank 73 to filter the air entering the hydraulic oil tank 73 through the air filter 77.

[0068] The high-precision digital hydraulic cylinder of the present embodiment operates as follows:

[0069] (I) Cylinder state maintaining

[0070] The servo motor 4 is connected to the driver, the driver provides potential energy to the servo motor 4, the output shaft of the servo motor 4 remains stationary, and the hydraulic oil power is provided by the hydraulic oil supply unit. The hydraulic oil enters the oil cavity 30 in the oil way valve seat 3 through the oil inlet nozzle 31. Since the output shaft of the servo motor 4 does not rotate, the hydraulic oil does not enter the rod cavity and the rodless cavity of the cylinder body 11, and the state of the cylinder body 11 remains stationary.

[0071] (II) Cylinder piston rod retraction

[0072] When the controller provides a positive pulse number to the driver, the output shaft of the servo motor 4 rotates in the positive direction. The greater the pulse number, the faster the rotation speed of the servo motor 4. The servo motor 4 rotates in the positive direction through the shaft coupling 16 to drive the main shaft 22 and the driving gear 331 to rotate clockwise. The driving gear 331 drives the driven gear 19 to rotate, and the hydraulic oil entering the oil inlet nozzle 31 is pressed into the first oil outlet oil way 321, the first oil supply pipeline 611 and the third pilot oil way 651. The hydraulic oil in the first oil supply pipeline 611 enters the rod cavity of the cylinder body 11, and pushes the piston 12 to move linearly backward relative to the cylinder body 11. The hydraulic oil in the third pilot oil way 651 opens the fourth hydraulic control valve group 642, so that the hydraulic oil in the rodless cavity of the cylinder body 11 flows back to the hydraulic oil tank 73 through the second pressure relief pipeline 632. The piston 12 moves backward to drive the feedback screw 15 to rotate in the positive direction through the screw seat 14. The second synchronous pulley 172 rotates in the positive direction, which drives the first synchronous pulley 171 to rotate in the positive direction through the synchronous belt 173, and further drives the target shaft 16 to rotate in the positive direction. The first encoder 21 senses the angular displacement signal of the target shaft 16 in real time, and further senses the angular displacement signal of the feedback screw 15, and uploads the angular displacement signal of the feedback screw 15 to the controller, so as to accurately and timely determine the moving speed and displacement of the piston 12. When the moving speed or displacement of the piston 12 deviates, the controller alarms, and the rotation speed of the output shaft of the servo motor 4 is adjusted through the controller to correct the moving speed or displacement of the piston 12.

[0073] (III) Cylinder piston rod extension

[0074] When the controller gives the driver negative pulse number, the output shaft of the servo motor 4 rotates reversely, and the greater the pulse number is, the faster the rotation speed of the servo motor 4 is. The servo motor 4 rotates reversely through the shaft coupling 16 to drive the spindle 22 and the driving gear 331 to rotate counterclockwise, the driving gear 331 drives the driven gear 19 to rotate, and the hydraulic oil entering the oil inlet 31 is pressed into the second oil outlet 322, the second oil supply pipeline 612 and the fourth pilot oil circuit 652. The hydraulic oil in the second oil supply pipeline 612 enters the rodless cavity of the cylinder 11 to push the piston 12 to move linearly forward relative to the cylinder 11; the hydraulic oil in the fourth pilot oil circuit 652 opens the third hydraulic control valve group 641, so that the hydraulic oil in the rod cavity of the cylinder 11 flows back to the hydraulic oil tank 73 through the first pressure relief pipeline 631. The piston 12 moves through the screw seat 14 to drive the feedback screw 15 to rotate reversely, the second synchronous wheel 172 at one end of the feedback screw 15 rotates reversely, the second synchronous wheel 172 drives the first synchronous wheel 171 to rotate reversely through the synchronous belt 173, and further drives the target shaft 16 to rotate reversely. The first encoder 21 senses the angular displacement signal of the target shaft 16 in real time, and further senses the angular displacement signal of the feedback screw 15, and uploads the angular displacement signal of the feedback screw 15 to the controller, so as to accurately and timely determine the moving speed and displacement of the piston 12. When the moving speed or displacement of the piston 12 deviates, the controller alarms, and the controller triggers the rotation speed of the output shaft of the servo motor 4 to correct the moving speed or displacement of the piston 12.

[0075] So far, the present embodiment has been described in detail in combination with the drawings. According to the above description, those skilled in the art should have a clear understanding of the high-precision digital hydraulic oil cylinder of the present application. The high-precision digital hydraulic oil cylinder of the present application has a lower requirement standard for the hydraulic oil supply unit, which only needs to provide a hydraulic oil with a set pressure. The gear set is driven by the servo motor 4 according to the pulse number to quantitatively press the hydraulic oil into the rod cavity or the rodless cavity of the cylinder 11, so as to accurately control the moving speed or displacement of the piston 12 of the oil cylinder. The moving speed or displacement of the piston 12 is directly fed back through the screw pair, so as to realize real-time and accurate closed-loop control of the moving speed or displacement of the piston 12.

[0076] The above-described specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only for specific embodiments of the present application and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A high-precision digital hydraulic cylinder, characterized in that: It includes a cylinder block, piston, piston rod, screw seat, feedback screw, first encoder, oil circuit valve seat, hydraulic oil supply unit, servo motor and controller; The piston is disposed inside the cylinder body, and the piston can reciprocate linearly relative to the cylinder body. One end of the piston rod is fitted and connected to the piston. The piston or piston rod is provided with the screw seat at one end, the feedback screw is threaded into the screw seat, and one end of the feedback screw is rotatably connected to the cylinder body; The screw seat can reciprocate linearly relative to the feedback screw, and at the same time, the screw seat can drive the feedback screw to rotate around its axis. The first encoder is used to sense the angular displacement signal of the feedback screw; The oil circuit valve seat has an oil chamber inside, and the oil circuit valve seat is provided with an oil inlet, a first oil outlet, and a second oil outlet that communicate with the oil chamber. The hydraulic oil supply unit is connected to the oil inlet, and the hydraulic oil supply unit injects hydraulic oil at a set pressure into the oil inlet. The first oil outlet and the second oil outlet are respectively connected to the rod chamber and the rodless chamber of the cylinder. The oil chamber of the oil circuit valve seat is rotatably connected to a gear set, and the output shaft of the servo motor is powered by the gear set. The output shaft of the servo motor rotates in either the forward or reverse direction to selectively press the hydraulic oil entering the inlet into either the first or second outlet oil passage via the gear set. The rotational speed of the output shaft of the servo motor is proportional to the amount of oil pumped into the first or second oil outlet circuit. The controller is connected to the first encoder and the servo motor via signal cables. The controller receives the angular displacement signal uploaded by the first encoder and controls the rotational speed of the output shaft of the servo motor. The gear set includes a meshing drive gear and a driven gear, and the output shaft of the servo motor is powered by the drive gear. The connection between the oil inlet and the oil chamber is located on one side of the middle position between the drive gear and the driven gear. The connection between the first oil outlet and the oil chamber is located on the other side of the middle position between the drive gear and the driven gear. The connection between the second oil outlet and the oil chamber is located on the outside of the drive gear and / or the driven gear. The first oil outlet is equipped with a first hydraulic control valve group, and the second oil outlet is equipped with a second hydraulic control valve group. The first oil outlet is connected to the hydraulic control end of the second hydraulic control valve group via a first pilot oil line, and the second oil outlet is connected to the hydraulic control end of the first hydraulic control valve group via a second pilot oil line. The hydraulic oil pressure in the first pilot oil line rises to a set pressure to trigger the second hydraulic control valve group to shut off the second oil outlet, and the hydraulic oil pressure in the second pilot oil line rises to a set pressure to trigger the first hydraulic control valve group to shut off the first oil outlet.

2. The high-precision digital hydraulic cylinder according to claim 1, characterized in that: The first oil outlet path is connected to the rod chamber of the cylinder via the first oil supply line, and a first check valve is provided on the first oil supply line. The second oil outlet path is connected to the rodless chamber of the cylinder via the second oil supply line, and a second check valve is provided on the second oil supply line. The first oil supply line is connected to the oil outlet side of the first check valve via a first pressure relief line, and a third hydraulic control valve assembly is installed on the first pressure relief line. The second oil supply line is connected to the oil outlet side of the second check valve via a second pressure relief line, and a fourth hydraulic control valve assembly is installed on the second pressure relief line. The first oil supply line is connected to the hydraulic control terminal of the fourth hydraulic control valve group via the third pilot oil line from the oil inlet side of the first check valve; the second oil supply line is connected to the hydraulic control terminal of the third hydraulic control valve group via the fourth pilot oil line from the oil inlet side of the second check valve. The hydraulic oil pressure in the third pilot circuit rises to the set pressure to trigger the fourth hydraulic control valve group to open the second pressure relief line, and the hydraulic oil pressure in the fourth pilot circuit rises to the set pressure to trigger the third hydraulic control valve group to open the first pressure relief line.

3. A high-precision digital hydraulic cylinder according to claim 1, characterized in that: The hydraulic oil supply unit includes an oil pump, an oil suction line, a hydraulic oil tank, a main oil supply line, a third check valve, a third pressure relief line, and a safety valve. The oil pump's inlet is connected to the hydraulic oil tank via a suction pipe, and the oil pump's outlet is connected to the inlet via a main oil supply pipe. A third check valve is installed on the main oil supply pipe, and the main oil supply pipe is connected to the hydraulic oil tank via a third pressure relief pipe on the outlet side of the third check valve. A safety valve is installed on the third pressure relief pipe.

4. A high-precision digital hydraulic cylinder according to claim 1, characterized in that: The output shaft of the servo motor is connected to the drive gear via a coupling.

5. A high-precision digital hydraulic cylinder according to claim 1, characterized in that: A target shaft is rotatably connected to the cylinder body. A first synchronous pulley is provided at the end of the target shaft. A second synchronous pulley is provided at one end of the feedback screw. A synchronous belt is connected between the first synchronous pulley and the second synchronous pulley. The first encoder senses the angular displacement signal of the feedback screw by sensing the angular displacement signal of the target shaft.

6. A high-precision digital hydraulic cylinder according to claim 1, characterized in that: It also includes a second encoder, and the controller is connected to the second encoder via a signal cable. The second encoder is used to sense the angular displacement signal of the output shaft of the servo motor, and the controller receives the angular displacement signal uploaded by the second encoder.

7. A high-precision digital hydraulic cylinder according to claim 1, characterized in that: The piston rod is configured with a hollow cavity inside, and the feedback screw is located inside the hollow cavity.

8. A high-precision digital hydraulic cylinder according to claim 1, characterized in that: The oil passage valve seat is located at the rear end of the cylinder body, and a motor bracket is provided on the oil passage valve seat. The servo motor is provided on the motor bracket.

9. A high-precision digital hydraulic cylinder according to claim 1, characterized in that: The cylinder body is provided with a hydraulic cylinder flange at the front end.

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