Synchronous control system for lifting a platform

Abstract

Synchronous control system for raising a platform, characterized in that it comprises a pressure source (1), a control valve (2), a speed control valve (3) and a lifting cylinder (4), wherein the lifting cylinder (4) follows the speed control valve (3) one-to-one, and several lifting cylinders and several speed control valves are provided, wherein the control valve (2) comprises an electromagnetic switching valve (201), a first one-way valve (202) and a second one-way valve (203), wherein an output port of the pressure source (1) is connected via a line to a first port of the electromagnetic switching valve (201), wherein a return port of the pressure source (1) is connected via a line to a second port of the electromagnetic switching valve (201), wherein a third port of the electromagnetic switching valve (201) is connected via a line to an inlet of the first one-way valve (202), wherein a fourth port of the electromagnetic switching valve (201) is connected via a line to an inlet of the second one-way valve (203), wherein in an unenergized state of the electromagnetic changeover valve (201) the first port and the second port do not communicate with the third port and the fourth port, wherein when the electromagnetic changeover valve (201) and a corresponding side of the first one-way valve (202) are energized the first port communicate with the third port and the second port communicate with the fourth port, wherein when the electromagnetic changeover valve (201) and a corresponding other side of the second one-way valve (203) are energized the first port communicate with the fourth port and the second port communicate with the third port, wherein the line between the third port of the electromagnetic switching valve (201) and the inlet of the first one-way valve (202) is further connected via a mutual control channel to a control port of the second one-way valve (203), wherein the line between the fourth port of the electromagnetic switching valve (201) and the inlet of the second one-way valve (203) is further connected via a mutual control channel to a control port of the first one-way valve (202), wherein an outlet of the first one-way valve (202) is connected via a line to the first port of each individual speed control valve (3), wherein a second port of each individual speed control valve (3) is connected via a line to a lower volume chamber of the corresponding lifting cylinder (4), wherein an outlet of the second one-way valve (203) is connected via a line to an upper volume chamber of the individual lifting cylinders (4).

Description

Technical field

[0001] The present invention relates to a control system, in particular a synchronous control system for lifting a platform for AGV logistics vehicles. State of the art

[0002] The platform lifting mechanism for AGV logistics vehicles must be synchronously controlled. Traditionally, synchronization is achieved using a throttle valve or hydraulic resistance, a flow control valve, a synchronous motor, an electrical proportional control, etc. However, existing control methods cannot adjust at low hydraulic oil flow rates and have disadvantages such as low control accuracy, difficult adjustment, high costs, complex systems, and limited integration.

[0003] Further state of the art is known from documents CN 1 07 217 877 B, CN 2 06 860 570 U, CN 2 04 900 377 U, DE 10 2010 026 853 A1 and CN 2 03 614 479 U.

[0004] Document CN 1 07 217 877 B discloses a technical scheme for the hydraulic multi-point support and synchronous control of parking equipment. In this scheme, displacement sensors are installed on each hydraulic cylinder and piston unit. A digital synchronous valve or a digital flow control valve is installed on a hydraulic oil path leading to each hydraulic cylinder and piston unit. A parking equipment control system receives output pulse signals from the displacement sensors in real time. If the piston displacement of each hydraulic cylinder and piston unit differs, control signals are sent to the digital synchronous valves or the digital flow control valves to adjust the flow control, ensuring that the piston displacements of the hydraulic cylinders and piston units are equal and thus achieving balanced raising and lowering of the upper layer plates.

[0005] Document CN 2 06 860 570 U discloses a double-acting cylindrical rack. This comprises a frame, a left-hand lifting cylinder, a right-hand lifting cylinder, a left-hand slide, a right-hand slide, a first fixed pulley, a second fixed pulley, a third fixed pulley, and a hydraulic system. The hydraulic system includes a first check valve, a second check valve, a third check valve, a fourth check valve, a fifth check valve, a sixth check valve, a seal, and a 4 / 3-way electromagnetic valve.

[0006] Document CN 2 04 900 377 U discloses an experimental model of a rack and pinion hydraulic circuit. This model is characterized by the fact that two control valves are connected to each geared motor, and that the connection method for the two control valves to all four geared motors is the same. In this model, the hydraulic pump inlet is connected to the oil tank, and the hydraulic pump outlet is connected to the filter inlet. The inlet of the second filter check valve and the outlet of the second check valve split into three branches. The P-shaped port of the second overflow valve is connected to the outlet of a branch route that exits through the second check valve, and the oil tank is connected to the T-shaped port of the second overflow valve.The second branch line, which is pulled out through the second check valve, connects to the inlet of the second control valve, the first Tribit cross solenoid valve of the output linkage of the second control valve connects to the P hydraulic fluid port, the third strip branch line, which is pulled out, connects to the third control valve through the oil circuit switch inlet, and the outlet of the third control valve connects to the second three-position four-way valve P outlet.

[0007] Document DE 10 2010 026 853 A1 discloses a valve insert for a valve, in particular for a control valve for controlling the flow of pressure medium in a camshaft adjuster. The valve insert comprises an insert housing in which a filter and a check valve with a closing element and a seat element are integrated. Easy assembly of the valve insert is ensured by permanently connecting at least the insert housing, the filter, and the seat element to each other, forming a prefabricated unit.

[0008] Finally, document CN 2 03 614 479 U describes a hydraulic device for lifting distributors with high synchronization accuracy, belonging to the technical field of continuous cast distributors. This device aims to significantly improve synchronization accuracy and compensate for synchronization errors of hydraulic cylinders during a lifting operation. Four hydraulic cylinders are connected to a synchronization control loop, which comprises four speed control valve groups, four speed control hydraulic one-way valves, four lifting hydraulic control one-way valves, and one electro-hydraulic changeover valve. Each speed control valve group is a rectifier plate consisting of four one-way valves and one speed control valve.Two ports of each rectifier plate are connected to the corresponding speed control hydraulic control one-way valve or the corresponding lifting hydraulic control one-way valve. Disclosure of the invention

[0009] In view of the shortcomings of the prior art, the present invention provides a synchronous control system for lifting a platform, which is suitable for controlling small flow rates and has high synchronization accuracy and a high degree of integration. The technical embodiment of the present invention consists of:

[0010] Synchronous control system for lifting a platform, comprising a pressure source, a control valve, a speed control valve and a lifting cylinder, wherein the lifting cylinder follows the speed control valve one to one, and multiple lifting cylinders and multiple speed control valves are provided, wherein the control valve comprises an electromagnetic switching valve, a first one-way valve and a second one-way valve.

[0011] An output port of the pressure source is connected via a line to a first port of the electromagnetic diverter valve, a return port of the pressure source is connected via a line to a second port of the electromagnetic diverter valve, a third port of the electromagnetic diverter valve is connected via a line to an inlet of the first one-way valve, and a fourth port of the electromagnetic diverter valve is connected via a line to an inlet of the second one-way valve.

[0012] In an unenergized state of the electromagnetic changeover valve, there is no connection from the first and second ports to the third and fourth ports, whereas when the electromagnetic changeover valve and a corresponding side of the first one-way valve are energized, the first port communicates with the third port and the second port with the fourth port, whereas when the electromagnetic changeover valve and a corresponding other side of the second one-way valve are energized, the first port communicates with the fourth port and the second port with the third port.

[0013] The line between the third port of the electromagnetic switching valve and the inlet of the first one-way valve is further connected via a mutual control channel to a control port of the second one-way valve, wherein the line between the fourth port of the electromagnetic switching valve and the inlet of the second one-way valve is further connected via a mutual control channel to a control port of the first one-way valve.

[0014] An outlet of the first one-way valve is connected via a line to the first port of each individual speed control valve, with a second port of each individual speed control valve being connected via a line to a lower volume chamber of the corresponding lifting cylinder.

[0015] One outlet of the second one-way valve is connected via a line to an upper volume chamber of the individual lifting cylinders.

[0016] Furthermore, it is provided that in the de-energized state of the electromagnetic switching valve, the first port communicates with the second port.

[0017] Furthermore, it is provided that the line between the output port of the hydraulic pressure source and the first port of the electromagnetic switching valve is fitted with a filter.

[0018] Furthermore, it is planned that the filter will be integrated into the control valve.

[0019] Furthermore, it is planned that four speed control valves and four lifting cylinders will be provided.

[0020] The advantages of the present invention are: 1) Precise control for small flow rates is achieved and synchronization accuracy is high, with the minimum controlled flow rate being 0.375 L / min and the synchronization accuracy being within 5%. 2) The control valve performs the function of switching and pressure maintenance, and its volume is compact. 3) No external servo controller is required and the costs are low. Description of the drawings

[0021] Fig. Figure 1 shows a hydraulic circuit diagram of the present invention. Detailed descriptions

[0022] The present invention is further described below in conjunction with the specific drawings and embodiments.

[0023] One embodiment of the present invention provides a synchronous control system for raising a platform, comprising a pressure source 1, a control valve 2, a speed control valve 3 and a lifting cylinder 4,

[0024] In general, four lifting cylinders 4 are required on the platform for AGV logistics vehicles, and accordingly, four speed control valves 3 are provided in the present embodiment, wherein the speed control valves 3 can manually adjust the flow rate precisely.

[0025] The control valve 2 can include an electromagnetic switching valve 201, a first one-way valve 202 and a second one-way valve 203, and also a filter 204.

[0026] An output port (the port with the arrow pointing in) Fig. 1) The pressure source 1 is connected via a line to a first port of the electromagnetic switching valve 201, wherein a return port of the pressure source 1 is connected via a line to a second port of the electromagnetic switching valve 201, wherein a third port of the electromagnetic switching valve 201 is connected via a line to an inlet of the first one-way valve 202, wherein a fourth port of the electromagnetic switching valve 201 is connected via a line to an inlet of the second one-way valve 203.

[0027] In Fig. 1 is the left port on the underside of the electromagnetic changeover valve 201, the first port being the right port on the underside, the second port being the left port on the top side, and the fourth port being the right port on the top side.

[0028] In an unenergized state of the electromagnetic changeover valve 201, the first terminal communicates with the second terminal, and there is no connection from the first and second terminals to the third and fourth terminals, wherein when the electromagnetic changeover valve 201 and a corresponding side of the first one-way valve 202 are energized, the first terminal communicates with the third terminal and the second terminal communicates with the fourth terminal, wherein when the electromagnetic changeover valve 201 and a corresponding other side of the second one-way valve 203 are energized, the first terminal communicates with the fourth terminal and the second terminal communicates with the third terminal.

[0029] The line between the third port of the electromagnetic switching valve 201 and the inlet of the first one-way valve 202 is further connected via a mutual control channel to a control port of the second one-way valve 203, so that when the first one-way valve 202 is opened by oil pressure, the second one-way valve 203 is also open to allow oil return, wherein, accordingly, the line between the fourth port of the electromagnetic switching valve 201 and the inlet of the second one-way valve 203 is further connected via a mutual control channel to a control port of the first one-way valve 202.

[0030] An outlet of the first one-way valve 202 is connected via a line to the first port of the individual speed control valve 3, wherein a second port of the individual speed control valve 3 is connected via a line to a lower volume chamber of the corresponding lifting cylinder 4.

[0031] Each outlet of the second one-way valve 203 is connected via a line to an upper volume chamber of the individual lifting cylinders 4.

[0032] The line between the output port of the hydraulic pressure source 1 and the first port of the electromagnetic switching valve 201 is fitted with a filter 204.

[0033] After pressure source 1 is activated, hydraulic oil flows through the first and third ports of the electromagnetic changeover valve 201, through the first one-way valve 202, and through the first one-way valve 202, provided that the electromagnetic changeover valve 201 and a corresponding side of the first one-way valve 202 are energized. The flow rate is precisely adjusted by the individual speed control valves 3, resulting in a stable required flow rate that precisely controls the ascent rate and synchronization of the four lifting cylinders. The hydraulic oil then flows into the lower chambers of the four lifting cylinders 4. With the continuous supply of hydraulic oil from pressure source 1, the four lifting cylinders are moved upwards, thus raising the platform.The hydraulic oil in the upper volume chambers of the four lifting cylinders 4 is drained and returns to the pressure source 1 via the second one-way valve 203 (now the control port of the second one-way valve is opened).

[0034] Accordingly, when the electromagnetic changeover valve 201 and a corresponding other side of the second one-way valve 203 are energized, hydraulic oil flows through the first and fourth ports of the electromagnetic changeover valve 201, through the second one-way valve 203, and then into the upper volume chambers of the individual lifting cylinders 4. With the continuous output of hydraulic oil from the pressure source 1, the four lifting cylinders are moved downwards. The hydraulic oil in the lower volume chambers of the four lifting cylinders 4 is drained and returns to the pressure source 1 via the first one-way valve 202 (now the control port of the first one-way valve is open).

[0035] According to the present invention, precise control of the flow output is enabled by the speed control valve and the interaction of the speed control valve with the control valve, in particular allowing the flow rate of less than one liter per minute to be precisely controlled, making it possible to control multiple flow rates, integrate multiple channels, and achieve a high degree of integration.

Claims

[1] Synchronous control system for lifting a platform, characterized by , that it comprises a pressure source (1), a control valve (2), a speed control valve (3) and a lifting cylinder (4), wherein the lifting cylinder (4) follows the speed control valve (3) one-to-one, and several lifting cylinders and several speed control valves are provided, wherein the control valve (2) comprises an electromagnetic switching valve (201), a first one-way valve (202) and a second one-way valve (203), wherein an output port of the pressure source (1) is connected via a line to a first port of the electromagnetic switching valve (201), wherein a return port of the pressure source (1) is connected via a line to a second port of the electromagnetic switching valve (201), wherein a third port of the electromagnetic switching valve (201) is connected via a line to an inlet of the first one-way valve (202), wherein a fourth port of the electromagnetic switching valve (201) is connected via a line to an inlet of the second one-way valve (203), wherein in an unenergized state of the electromagnetic changeover valve (201) the first port and the second port do not communicate with the third port and the fourth port, wherein when the electromagnetic changeover valve (201) and a corresponding side of the first one-way valve (202) are energized the first port communicate with the third port and the second port communicate with the fourth port, wherein when the electromagnetic changeover valve (201) and a corresponding other side of the second one-way valve (203) are energized the first port communicate with the fourth port and the second port communicate with the third port, wherein the line between the third port of the electromagnetic switching valve (201) and the inlet of the first one-way valve (202) is further connected via a mutual control channel to a control port of the second one-way valve (203), wherein the line between the fourth port of the electromagnetic switching valve (201) and the inlet of the second one-way valve (203) is further connected via a mutual control channel to a control port of the first one-way valve (202), wherein an outlet of the first one-way valve (202) is connected via a line to the first port of each individual speed control valve (3), wherein a second port of each individual speed control valve (3) is connected via a line to a lower volume chamber of the corresponding lifting cylinder (4), wherein an outlet of the second one-way valve (203) is connected via a line to an upper volume chamber of the individual lifting cylinders (4). [2] Synchronous control system for lifting a platform according to claim 1, characterized by , that in the unenergized state of the electromagnetic switching valve (201) the first terminal communicates with the second terminal. [3] Synchronous control system for lifting a platform according to claim 1 or 2, characterized by , that the line between the output port of the hydraulic pressure source (1) and the first port of the electromagnetic switching valve (201) is fitted with a filter (204). [4] Synchronous control system for lifting a platform according to claim 3, characterized by , that the filter (204) is integrated into the control valve (2). [5] Synchronous control system for lifting a platform according to any of the preceding claims, characterized bythat four speed control valves (3) and four lifting cylinders (4) are provided.

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