A self-lifting hydraulic control system for a transfer vehicle

Abstract

The present invention discloses a self-lifting hydraulic control system for a transfer vehicle, comprising: an oil cylinder, an oil tank, a first control valve group, a second control valve group, and a reversing valve; when the reversing valve is in a first position, a first port and a second port are connected, oil in the oil tank enters a rodless chamber, and when the pressure of the rodless chamber reaches a first preset ratio to the pressure of the rod chamber, the first control valve group is closed, the second control valve group is connected, and oil in the rod chamber flows back to the oil tank, causing the piston rod to move toward the rod chamber; when the reversing valve is in a second position, the first port and a third port are connected, oil in the oil tank enters the rod chamber, and when the pressure of the rod chamber reaches a second preset ratio to the pressure of the rodless chamber, the second control valve group is closed, the first control valve group is connected, and oil in the rodless chamber flows back to the oil tank, causing the piston rod to move toward the rodless chamber. The present invention can achieve lifting or lowering of the oil cylinder by operating the reversing valve once.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic control, and in particular to a self-lifting hydraulic control system for a transfer vehicle. Background Art

[0002] Ship transportation is a critical consideration during both shipbuilding and repair. Traditionally, small or split-body ships are transported using a single or a few flatbed trucks. However, considering the use of multiple flatbed trucks for transporting large ships increases the difficulty of implementing synchronized control, reduces safety and reliability, and increases the risk of failure. In the event of an accident, the shipowner would suffer significant losses, making this approach unsuitable. This led to the development of a transfer system for large ships. This transfer system utilizes 96 transfer trucks for transporting medium- to large-sized ships. The number of trolleys can be adjusted based on the size of the ship. A self-propelled hydraulic station provides oil to lift and transport the ship. Large shipyards typically have multiple ship repair and manufacturing berths. Deploying a transfer system for each berth would require significant floor space and increase costs. Therefore, a single transfer system, capable of reaching each repair berth, requires both longitudinal and transverse travel, requiring wheel steering to be considered during its design.

[0003] Wheel steering is primarily achieved through hydraulic control. The transfer cart is lifted off the track by a hydraulic cylinder, and then manually steered. Currently, the hydraulic cylinder lifting system in the market requires multiple operations of different ball valves to raise the transfer cart, and then multiple operations to reset it. This method is cumbersome and prone to operational errors. Furthermore, due to the large number of transfer carts, errors are prone to occur, which can negatively impact ship transshipment and pose certain risks to the transportation of such large vessels. Summary of the Invention

[0004] The present invention aims to solve the problem that the transfer system requires multiple operations to raise the cylinder and thus steer the transfer vehicle, and multiple operations to reposition the cylinder. The present invention provides a self-lifting hydraulic control system for a transfer vehicle that can raise or retract the cylinder with a single operation.

[0005] To solve the above technical problems, the embodiments of the present invention disclose a self-lifting hydraulic control system for a transfer vehicle, comprising:

[0006] The oil cylinder has a piston rod inside, and the oil cylinder includes a rod cavity and a rodless cavity, and the piston rod is located in the rod cavity;

[0007] tank;

[0008] a first control valve group, connected to the oil tank and the rodless chamber respectively;

[0009] The second control valve group is communicated with the first control valve group, the oil tank and the rod chamber respectively;

[0010] A reversing valve having a first port, a second port, and a third port; wherein the first port is connected to the oil tank, the second port is connected to the rodless chamber, the first control valve group, and the second control valve group, respectively, and the third port is connected to the rod chamber, the first control valve group, and the second control valve group, respectively;

[0011] When the reversing valve is in the first position, the first port and the second port are connected, the third port is closed, and the oil in the oil tank flows into the rodless chamber. When the pressure of the rodless chamber and the pressure of the rod chamber reach a first preset ratio, the first control valve group is closed and the second control valve group is connected, and the oil in the rod chamber flows back to the oil tank, so that the piston rod moves toward the rod chamber.

[0012] When the reversing valve is in the second position, the first port and the third port are connected, the second port is closed, the oil in the oil tank enters the rod chamber, and when the pressure of the rod chamber and the pressure of the rodless chamber reach a second preset ratio, the second control valve group is closed, the first control valve group is connected, and the oil in the rodless chamber flows back to the oil tank, so that the piston rod moves toward the direction of the rodless chamber.

[0013] By adopting the above technical solution, by operating the reversing valve once, the reversing valve is placed in different positions. The first control valve group and the second control valve group control whether the hydraulic oil in the rod chamber and the rodless chamber can flow back to the oil tank, thereby completing the extension and retraction of the piston rod, and then driving the lifting and lowering of the oil cylinder.

[0014] According to another specific embodiment of the present invention, the first control valve group includes a first hydraulically controlled one-way valve and a first damping valve, and the second control valve group includes a second hydraulically controlled one-way valve and a second damping valve, wherein:

[0015] The oil inlet of the first hydraulically controlled one-way valve is connected to the oil tank through the first damping valve, the oil outlet of the first hydraulically controlled one-way valve is connected to the rodless chamber and the second control oil port of the second hydraulically controlled one-way valve respectively, and the first control oil port of the first hydraulically controlled one-way valve is connected to the rod chamber and the oil outlet of the second hydraulically controlled one-way valve respectively;

[0016] The oil inlet of the second hydraulically controlled one-way valve is connected to the oil tank through the second damping valve, the oil outlet of the second hydraulically controlled one-way valve is connected to the rod chamber and the first control oil port of the first hydraulically controlled one-way valve respectively, and the second control oil port of the second hydraulically controlled one-way valve is connected to the rodless chamber and the oil outlet of the first hydraulically controlled one-way valve respectively.

[0017] According to another specific embodiment of the present invention, it also includes:

[0018] a first one-way valve, disposed downstream of the third port, wherein an oil outlet of the first one-way valve is in communication with the rod chamber;

[0019] The second one-way valve is arranged downstream of the second port, and the oil outlet of the second one-way valve is communicated with the rodless cavity.

[0020] According to another specific embodiment of the present invention, a third one-way valve is further included, which is arranged upstream of the rod chamber.

[0021] According to another specific embodiment of the present invention, a third damping valve is further provided upstream of the reversing valve.

[0022] According to another specific embodiment of the present invention, a relief valve is further included, wherein the oil inlet of the relief valve is communicated with the rod chamber, and the oil outlet of the relief valve is communicated with the oil tank.

[0023] According to another embodiment of the present invention, the valve further comprises a plurality of pressure monitors for detecting the pressure of the oil flowing into or out of each valve.

[0024] According to another specific embodiment of the present invention, the reversing valve is a three-way ball valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A hydraulic schematic diagram of a self-lifting hydraulic control system for a transfer vehicle provided by one embodiment of the present invention is shown;

[0026] Figure 2 A schematic diagram showing the connection between the first control valve group and the second control valve group provided in one embodiment of the present invention is shown. DETAILED DESCRIPTION

[0027] The following is an explanation of the embodiments of the present invention by specific specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Although the description of the present invention will be introduced in conjunction with the preferred embodiment, this does not mean that the features of this invention are limited to this embodiment. On the contrary, the purpose of introducing the invention in conjunction with the embodiment is to cover other options or modifications that may be extended based on the claims of the present invention. In order to provide a deep understanding of the present invention, the following description will contain many specific details. The present invention can also be implemented without using these details. In addition, in order to avoid confusion or blurring the focus of the present invention, some specific details will be omitted in the description. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0028] It should be noted that in this specification, similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0029] The terms "first," "second," "third," "fourth," etc. are only used to distinguish and describe, and should not be understood as indicating or implying relative importance.

[0030] In the description of this embodiment, it should be noted that, unless otherwise specified or limited, the terms "disposed," "connected," and "connected" should be understood broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this embodiment based on specific circumstances.

[0031] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0032] In existing self-lifting control systems, when extending the cylinder, the oil return ball valve in the rod chamber must be opened, the oil return ball valve in the rodless chamber must be closed, and then the three-way ball valve must be operated to extend the cylinder. To retract the cylinder, the oil return ball valve in the rodless chamber must be opened, the oil return ball valve in the rod chamber must be closed, and then the three-way ball valve must be operated. This requires multiple switching between different ball valves.

[0033] like Figure 1 As shown, one embodiment of the present invention provides a self-lifting hydraulic control system for a transfer vehicle, comprising:

[0034] The oil cylinder 1 has a piston rod 13 inside. The oil cylinder 1 includes a rod cavity 15 and a rodless cavity 14. The piston rod 13 is located in the rod cavity 15.

[0035] Fuel tank 2;

[0036] The first control valve group 3 is connected to the oil tank 2 and the rodless chamber 14 respectively;

[0037] The second control valve group 4 is connected to the first control valve group 3, the oil tank 2 and the rod chamber 15 respectively;

[0038] The reversing valve 5 has a first port 5a, a second port 5b, and a third port 5c; wherein the first port 5a is in communication with the oil tank 2, the second port 5b is in communication with the rodless chamber 14, the first control valve group 3, and the second control valve group 4, respectively; and the third port 5c is in communication with the rod chamber 15, the first control valve group 3, and the second control valve group 4, respectively.

[0039] When the reversing valve 5 is in the first position, the first port 5a and the second port 5b are connected, and the third port 5c is closed, and the oil in the oil tank 2 enters the rodless chamber 14. When the pressure of the rodless chamber 14 and the pressure of the rod chamber 15 reach a first preset ratio, the first control valve group 3 is closed and the second control valve group 4 is connected, and the oil in the rod chamber 15 flows back to the oil tank 2, so that the piston rod 13 moves in the direction of the rod chamber 15.

[0040] When the reversing valve 5 is in the second position, the first port 5a and the third port 5c are connected, the second port 5b is closed, and the oil in the oil tank 2 enters the rod chamber 15. When the pressure of the rod chamber 15 and the pressure of the rodless chamber 14 reach a second preset ratio, the second control valve group 4 is closed, the first control valve group 3 is connected, and the oil in the rodless chamber 14 flows back to the oil tank 2, so that the piston rod 13 moves toward the rodless chamber 14.

[0041] Specifically, in this embodiment, the oil cylinder 1 includes a cylinder body 11, a piston 12, and a piston rod 13 connected to the piston 12. Specifically, the piston 12 is disposed within the cylinder body 11 and divides the internal space of the cylinder body 11 into two chambers, one of which is provided with the piston rod 13 and is referred to as the rod chamber 15 in this embodiment, while the other chamber, which is not provided with the piston rod 13, is referred to as the rodless chamber 14.

[0042] In this embodiment, when hydraulic oil is continuously injected into the rodless chamber 14 and the hydraulic oil in the rod chamber 15 flows out, the piston rod 13 extends. At this time, the cylinder 1 is in a jacking state, and the transfer vehicle can be lifted up; when hydraulic oil is continuously injected into the rod chamber 15 and the hydraulic oil in the rodless chamber 14 flows out, the piston rod 13 retracts. At this time, the cylinder 1 is in a descending state, and the transfer vehicle can be reset.

[0043] By adopting the above technical solution, by operating the reversing valve 5 once, the reversing valve 5 is placed in different positions, and the first control valve group 3 and the second control valve group 4 control the rod chamber 15 and the rodless chamber 14, one of which takes in oil and the other discharges oil, thereby completing the extension and retraction of the piston rod 13, and then driving the lifting and lowering of the oil cylinder 1.

[0044] Specifically, in this embodiment, the reversing valve 5 is a three-way ball valve. The first port 5a is the oil inlet. When the valve core of the reversing valve 5 is in the first position, the second port 5b is the oil outlet, and the third port 5c is closed. When the valve core of the reversing valve 5 is in the second position, the second port 5b is closed, and the third port 5c is the oil outlet. Figure 1 As shown, when the reversing valve 5 is in the second position, the first port 5a and the third port 5c are in conduction.

[0045] More specifically, in this embodiment, the self-jacking hydraulic control system further includes a hydraulic pump 21 disposed between the oil tank 2 and the reversing valve 5, and a fourth one-way valve 22 disposed in the oil circuit between the hydraulic pump 21 and the reversing valve 5, with the oil outlet of the fourth one-way valve 22 facing the reversing valve 5. Hydraulic oil from the oil tank 2 is pumped into the pipeline by the hydraulic pump 21. The fourth one-way valve 22 is disposed in the oil circuit between the reversing valve 5 and the hydraulic pump 21 to prevent backflow of the hydraulic oil.

[0046] In this embodiment, the oil inlet of the first control valve group 3 is connected to the oil tank 2, the oil outlet is connected to the rodless chamber 14, and the first control oil port is connected to the rod chamber 15. The oil inlet of the second control valve group 4 is connected to the oil tank 2, the oil outlet is connected to the rod chamber 15, and the second control oil port is connected to the rodless chamber 14. In other words, the rodless chamber 14 is connected to the oil outlet of the first control valve group 3 and the second control oil port of the second control valve group 4, respectively; the rod chamber 15 is connected to the first control oil port of the first control valve group 3 and the oil outlet of the second control valve group 4, respectively. It is worth noting that the oil inlet and oil outlet of the first control valve group 3 refer to the oil ports when the first control valve group 3 is conducting in the forward direction. That is, when the ratio of the pressure of the first control oil port to the pressure of the oil outlet of the first control valve group 3 does not reach the preset ratio, oil is introduced from the oil inlet and discharged from the oil outlet. However, when the pressure of the first control oil port to the pressure of the oil outlet reaches the preset ratio, the first control valve group 3 is conducting in the reverse direction, that is, oil is introduced from the aforementioned oil outlet and discharged from the aforementioned oil inlet. The same applies to the second control valve group 4 and the first control valve group 3.

[0047] When cylinder 1 is in the lifting position to lift the transfer vehicle, reversing valve 5 is operated, connecting first port 5a and second port 5b. Hydraulic pump 21 pumps hydraulic oil from tank 2 into the pipeline, passing through reversing valve 5 and entering rodless chamber 14. At this time, second control valve group 4 is closed, preventing the hydraulic oil in rod chamber 15 from flowing out, thus maintaining pressure in rod chamber 15. As hydraulic oil enters rodless chamber 14, the pressure in rodless chamber 14 gradually increases. Since the first control port of first control valve group 3 is connected to rod chamber 15, and the oil outlet of first control valve group 3 is connected to rodless chamber 14, when the pressure ratio between the first control port and the oil outlet of first control valve group 3 reaches a first predetermined ratio, first control valve group 3 closes and second control valve group 4 opens, allowing the hydraulic oil in rod chamber 15 to flow back into tank 2, thereby extending piston rod 13 and lifting cylinder 1, thereby lifting the transfer vehicle. On the contrary, when the oil cylinder 1 wants to be in the retracted position to reset the transfer vehicle, the reversing valve 5 is operated to make the reversing valve 5 in a state where the first port 5a and the third port 5c are connected, and the hydraulic pump 21 draws the hydraulic oil in the oil tank 2 into the pipeline, and the hydraulic oil enters the rod chamber 15 through the reversing valve 5. At this time, the first control valve group 3 is closed, and the hydraulic oil in the rodless chamber 14 cannot flow out, so the rodless chamber 14 is in a pressure maintaining state. As the hydraulic oil enters the rod chamber 15, the pressure in the rod chamber 15 gradually increases. Since the second control oil port of the second control valve group 4 is connected to the rodless chamber 14, the oil outlet of the second control valve group 4 is connected to the rod chamber 15. Therefore, when the pressure ratio of the second control oil port of the second control valve group 4 to the oil outlet of the second control valve group 4 reaches a second preset ratio, the second control valve group 4 is closed and the first control valve group 3 is turned on, so that the hydraulic oil in the rodless chamber 14 flows back to the oil tank 2, thereby realizing the retraction of the piston rod 13 and the lowering of the cylinder 1, so that the transfer vehicle can slowly descend with the cylinder 1 according to its own weight.

[0048] It is worth noting that, in the present invention, the first preset ratio and the second preset ratio may be the same or different, and the present invention does not impose any limitation on this, and the ratio may be selected according to actual needs.

[0049] Furthermore, in this embodiment, the first control valve group 3 includes a first hydraulically controlled one-way valve 31 and a first damping valve 32, and the second control valve group 4 includes a second hydraulically controlled one-way valve 41 and a second damping valve 42, wherein:

[0050] The oil inlet a1 of the first hydraulically controlled one-way valve 31 is connected to the oil tank 2 through the first damping valve 32. The oil outlet b1 of the first hydraulically controlled one-way valve 31 is connected to the rodless chamber 14 and the second control oil port c2 of the second hydraulically controlled one-way valve 41 respectively. The first control oil port c1 of the first hydraulically controlled one-way valve 31 is connected to the rod chamber 15 and the oil outlet b2 of the second hydraulically controlled one-way valve 41 respectively.

[0051] The oil inlet a2 of the second hydraulically controlled one-way valve 41 is connected to the oil tank 2 through the second damping valve 42, the oil outlet b2 of the second hydraulically controlled one-way valve 41 is respectively connected to the rod chamber 15 and the first control oil port c1 of the first hydraulically controlled one-way valve 31, and the second control oil port c2 of the second hydraulically controlled one-way valve 41 is respectively connected to the rodless chamber 14 and the oil outlet b1 of the first hydraulically controlled one-way valve 31.

[0052] Specifically, if Figure 2 As shown, the first hydraulically controlled one-way valve 31 has an oil inlet a1, an oil outlet b1, and a first control oil port c1. The second hydraulically controlled one-way valve 41 has an oil inlet a2, an oil outlet b2, and a second control oil port c2. For the first hydraulically controlled one-way valve 31, when the pressure of the first control oil port c1 and the pressure of the oil outlet b1 do not reach a preset ratio, that is, when the pressure guide ratio of the first hydraulically controlled one-way valve 31 is not reached, the first hydraulically controlled one-way valve 31 conducts forward, with oil entering through the oil inlet a1 and exiting through the oil outlet b1. When the pressure of the first control oil port c1 and the pressure of the oil outlet b1 reach a preset ratio, that is, when the pressure guide ratio of the first hydraulically controlled one-way valve 31 is reached, the first hydraulically controlled one-way valve 31 conducts reverse, with oil entering through the oil outlet b1 and exiting through the oil inlet a1. The second hydraulically controlled one-way valve 41 operates similarly to the first hydraulically controlled one-way valve 31.

[0053] Specifically, in this embodiment, the first preset ratio is the pressure guide ratio of the second hydraulically-controlled one-way valve 41, and the second preset ratio is the pressure guide ratio of the first hydraulically-controlled one-way valve 31. In a specific embodiment of the present invention, the pressure guide ratios of the first hydraulically-controlled one-way valve 31 and the second hydraulically-controlled one-way valve 41 are both 3:1. That is, when the pressure at the control oil port reaches 1 / 3 of the pressure at the oil outlet, the first hydraulically-controlled one-way valve 31 and the second hydraulically-controlled one-way valve 41 are reversely guided, and hydraulic oil enters from the oil outlet and flows out from the oil inlet.

[0054] When the piston rod 13 of the oil cylinder 1 is extended, hydraulic oil enters the rodless chamber 14. At this time, because the pressure at the first control port c1 of the first hydraulically-controlled one-way valve 31 is greater than the pressure at the oil outlet b1, the first hydraulically-controlled one-way valve 31 remains open, and the hydraulic oil in the rodless chamber 14 returns directly to the oil tank 2. However, since the first damping valve 32 is located in front of the oil inlet a1 of the first hydraulically-controlled one-way valve 31, the first damping valve 32 restricts the flow of hydraulic oil, causing the pressure in the rodless chamber 14 to gradually increase. At this time, the pressure in the rod chamber 15 is maintained, resulting in a pressure differential between the rod chamber 15 and the rodless chamber 14. Because the second control port c2 of the second hydraulically piloted check valve 41 communicates with the rodless chamber 14, and its outlet b2 communicates with the rod chamber 15, when the pressure differential between the rod chamber 15 and the rodless chamber 14 reaches the pilot pressure ratio of the second hydraulically piloted check valve 41, the second hydraulically piloted check valve 41 reverses conduction, allowing the hydraulic oil in the rod chamber 15 to flow back to the tank 2 through the second hydraulically piloted check valve 41. The pressure in the rod chamber 15 drops to zero, and the pressure in the first control port c1 of the first hydraulically piloted check valve 31 also drops to zero, closing the first hydraulically piloted check valve 31 and automatically extending the cylinder 1. Conversely, when the piston rod 13 of the cylinder 1 is to be retracted, hydraulic oil enters the rod chamber 15. At this time, because the pressure in the second control port c2 of the second hydraulically piloted check valve 41 is greater than the pressure in the outlet b2, the second hydraulically piloted check valve 41 opens, allowing the hydraulic oil in the rod chamber 15 to flow directly back to the tank 2. However, since a second damping valve 42 is provided in front of the oil inlet a2 of the second hydraulically-controlled one-way valve 41, it restricts the flow of hydraulic oil, causing the pressure in the rod chamber 15 to gradually increase. At this time, the pressure in the rodless chamber 14 is maintained, resulting in a pressure differential between the rodless chamber 14 and the rod chamber 15. Since the first control oil port c1 of the first hydraulically-controlled one-way valve 31 is connected to the rod chamber 15, and the oil outlet b1 is connected to the rodless chamber 14, when the pressure differential between the rodless chamber 14 and the rod chamber 15 reaches the pilot pressure ratio of the first hydraulically-controlled one-way valve 31, the first hydraulically-controlled one-way valve 31 reverses conduction, and the hydraulic oil in the rodless chamber 14 flows back to the tank 2 through the first hydraulically-controlled one-way valve 31, reducing the pressure in the rodless chamber 14 to zero. At this time, the pressure at the second control oil port c2 of the second hydraulically-controlled one-way valve 41 also drops to zero, causing the second hydraulically-controlled one-way valve 41 to close, thereby achieving automatic retraction of the cylinder 1.

[0055] Furthermore, the first one-way valve 61 is provided downstream of the third port 5c, with the oil outlet of the first one-way valve 61 communicating with the rod chamber 15; and the second one-way valve 62 is provided downstream of the second port 5b, with the oil outlet of the second one-way valve 62 communicating with the rodless chamber 14. With the above technical solution, the first one-way valve 61 is provided in the oil path between the third port 5c of the reversing valve 5 and the rod chamber 15 to prevent the hydraulic oil in the rod chamber 15 from flowing back from the reversing valve 5 to the oil tank 2. The second one-way valve 62 is provided in the oil path between the second port 5b of the reversing valve 5 and the rodless chamber 14 to prevent the hydraulic oil in the rodless chamber 14 from flowing back through the reversing valve 5 to the oil tank 2.

[0056] Furthermore, a third one-way valve 63 is provided upstream of the rod chamber 15. Specifically, the oil inlet of the third one-way valve 63 is connected to the oil outlet of the automatic control cabinet (not shown), and the oil outlet of the third one-way valve 63 is connected to the rod chamber 15. With this technical solution, a certain amount of hydraulic oil is maintained in the rod chamber 15 during the operation of the transfer vehicle, which can keep the piston rod 13 in the retracted state, preventing the piston rod 13 from falling and damaging the oil cylinder 1 and, in turn, the transfer vehicle.

[0057] Furthermore, a third damping valve 51 is provided upstream of the reversing valve 5 .

[0058] It is worth noting that, in the present invention, the first damping valve 32, the second damping valve 42, and the third damping valve 51 are used to regulate the flow of hydraulic oil. The size of the damping orifices of the damping valves can be set according to different system requirements. Of course, the sizes of the damping orifices of the three damping valves can be set to be the same or different. In a specific embodiment of the present invention, the size of the damping orifices is 2 mm.

[0059] Furthermore, a first relief valve 7 is included. The oil inlet of the first relief valve 7 is connected to the rod chamber 15, and the oil outlet of the first relief valve 7 is connected to the fuel tank 2. The above technical solution prevents the pressure in the rod chamber 15 from being too high. When the pressure in the rod chamber 15 is too high, the oil in the rod chamber 15 flows back to the fuel tank 2 through the first relief valve 7.

[0060] Specifically, a second relief valve 23 is provided upstream of the reversing valve 5. More specifically, the oil inlet of the second relief valve 23 is connected to the oil outlet of the fourth one-way valve 22, and the oil outlet of the second relief valve 23 is connected to the fuel tank 2. This technical solution prevents the hydraulic oil entering the reversing valve 5 from becoming overly pressurized.

[0061] Furthermore, the system also includes multiple pressure monitors, which can be pressure sensors, pressure relays, etc., and are used to detect the pressure of the oil flowing into or out of each valve. By adopting the above technical solution, multiple monitoring points are set up so that the fault point can be found promptly when a system failure occurs. Specifically, in this embodiment, the multiple pressure monitors include a first pressure monitor 81, a second pressure monitor 82, a third pressure monitor 83, a fourth pressure monitor 84, and a fifth pressure monitor 85. The first pressure monitor 81 is connected to the oil tank 2 for detecting the pressure of the oil tank 2; the second pressure monitor 82 is connected to the rod chamber 15 for detecting the pressure within the rod chamber 15; the third pressure monitor 83 is connected to the rodless chamber 14 for detecting the pressure within the rodless chamber 14; the fourth pressure monitor 84 is connected to the oil inlet of the third check valve 63 for detecting the pressure of the hydraulic oil from the automatic cabinet; and the fifth pressure monitor 85 is connected to the oil inlet of the reversing valve 5 for detecting the pressure of the hydraulic oil entering the reversing valve 5.

[0062] Working principle of the present invention:

[0063] Lifting operation: When the reversing valve 5 is operated to place the oil cylinder 1 in the lifting position, the first port 5a and the second port 5b of the reversing valve 5 are connected, and the third port 5c is closed. The hydraulic oil enters the oil circuit from the oil tank 2 through the hydraulic pump 21 and enters the rodless chamber 14 of the oil cylinder 1 through the second port 5b of the reversing valve 5. At this time, since the oil cylinder 1 was previously in the retracted state, the pressure in the rod chamber 15 is in a pressure-maintaining state. Since the oil outlet b1 of the first hydraulically controlled one-way valve 31 is connected to the rodless chamber 14, and the first control oil port c1 of the first hydraulically controlled one-way valve 31 is connected to the rod chamber 15, the oil outlet b1 is the pressure in the rodless chamber 14, and the first control oil port c1 is the pressure in the rod chamber 15. Since the pressure in the rod chamber 15 is in a pressure-maintaining state, the pressure of the first control oil port c1 is greater than the pressure of the oil outlet b1, so the first hydraulically controlled one-way valve 31 is directly reversed. At this time, the hydraulic oil coming out of the second port 5b of the reversing valve 5 enters the rodless chamber 14 and returns directly to the oil tank 2 from the first hydraulically controlled one-way valve 31. At this time, no pressure can be built up in the rodless chamber 14 to push the piston rod 13 to extend. However, since a first damping valve 32 is provided in front of the oil inlet a1 of the first hydraulically controlled one-way valve 31, the first damping valve 32 limits the flow of hydraulic oil flowing back out of the first hydraulically controlled one-way valve 31, thereby generating back pressure at the oil outlet b1 of the first hydraulically controlled one-way valve 31. This pressure is the pressure in the rodless chamber 14, that is, the pressure in the rodless chamber 14 gradually increases. When the pressure in the rodless chamber 14 reaches 1 / 3 times the pressure in the rod chamber 15, since the oil outlet b2 of the second hydraulically controlled one-way valve 41 is connected to the rod chamber 15, the second control oil port c2 of the second hydraulically controlled one-way valve 41 is connected to the rodless chamber 14. That is, when the pressure ratio of the second control oil port c2 to the oil outlet b2 is 1:3, the second hydraulically controlled one-way valve 41 is reversed. At this time, the pressure in the rod chamber 15 is completely released, and the pressure almost drops to 0. At the same time, a loop is formed between the rod chamber 15 and the oil tank 2, and the hydraulic oil directly returns to the oil tank 2; at this time, since the pressure in the rod chamber 15 almost drops to 0, the pressure of the first control oil port c1 of the first hydraulically controlled one-way valve 31 is 0. Therefore, the first hydraulically controlled one-way valve 31 is closed, and the pressure in the rodless chamber 14 directly rises to the preset pressure, thereby lifting the oil cylinder 1 and completing the lifting control of the transfer vehicle.

[0064] Lowering operation: When the reversing valve 5 is operated to lower the oil cylinder 1, the first port 5a and the third port 5c of the reversing valve 5 are connected, and the second port 5b is closed. The hydraulic oil enters the oil circuit from the oil tank 2 through the hydraulic pump 21 and enters the rod chamber 15 of the oil cylinder 1 through the third port 5c of the reversing valve 5. At this time, since the oil cylinder 1 was previously in the extended state, the pressure in the rodless chamber 14 is in a pressure-maintaining state. Since the oil outlet b2 of the second hydraulically controlled one-way valve 41 is connected to the rod chamber 15, and the second control oil port c2 of the second hydraulically controlled one-way valve 41 is connected to the rodless chamber 14, the oil outlet b2 is the pressure in the rod chamber 15, and the second control oil port c2 is the pressure in the rodless chamber 14. Since the pressure in the rodless chamber 14 is in a pressure-maintaining state, the pressure of the second control oil port c2 is greater than the pressure of the oil outlet b2, so the second hydraulically controlled one-way valve 41 is directly reversed. At this time, the hydraulic oil coming out of the third port 5c of the reversing valve 5 enters the rod chamber 15 and directly returns to the oil tank 2 from the second hydraulically controlled one-way valve 41. At this time, no pressure can be built up in the rod chamber 15 to push the piston rod 13 to retract. However, since a second damping valve 42 is provided in front of the oil inlet a2 of the second hydraulically controlled one-way valve 41, the second damping valve 42 limits the flow of hydraulic oil flowing back out of the second hydraulically controlled one-way valve 41, thereby generating back pressure at the oil outlet b2 of the second hydraulically controlled one-way valve 41. This pressure is the pressure in the rod chamber 15, which means that the pressure in the rod chamber 15 gradually increases. When the pressure in the rod chamber 15 reaches 1 / 3 times the pressure in the rodless chamber 14, since the oil outlet b1 of the first hydraulically controlled one-way valve 31 is connected to the rodless chamber 14, the first control oil port c1 of the first hydraulically controlled one-way valve 31 is connected to the rod chamber 15. That is, when the pressure ratio of the first control oil port c1 to the oil outlet b1 is 1:3, the first hydraulically controlled one-way valve 31 is reversed, and the pressure in the rodless chamber 14 is completely released. The pressure almost drops to 0. At the same time, a loop is formed between the rodless chamber 14 and the oil tank 2, and the hydraulic oil directly returns to the oil tank 2; at this time, since the pressure in the rodless chamber 14 almost drops to 0, the pressure of the second control oil port c2 of the second hydraulically controlled one-way valve 41 is 0. Therefore, the second hydraulically controlled one-way valve 41 is closed, and the pressure in the rod chamber 15 directly rises to the preset pressure, thereby retracting the cylinder 1, and the transfer vehicle can complete the descent by its own weight.

[0065] According to the self-lifting hydraulic control system for the transfer vehicle provided by the present invention, the lifting or lowering of the oil cylinder 1 can be completed by operating the reversing valve 5 once. The simple operation method improves the convenience of operation and the reliability of the system, and reduces the risk of the transfer system.

[0066] Although the present invention has been illustrated and described with reference to certain preferred embodiments thereof, it should be understood by those skilled in the art that the above description is provided as a further detailed description of the present invention in conjunction with specific embodiments thereof, and that the specific implementation of the present invention is not limited to these descriptions. Those skilled in the art may make various changes in form and details, including simple deductions or substitutions, without departing from the spirit and scope of the present invention.

Claims

1. A self-lifting hydraulic control system for a transfer vehicle, characterized in that: include: An oil cylinder, wherein a piston rod is provided inside the oil cylinder, the oil cylinder comprises a rod cavity and a rodless cavity, and the piston rod is located in the rod cavity; tank; a first control valve group, connected to the oil tank and the rodless chamber respectively; a second control valve group, connected to the first control valve group, the oil tank and the rod chamber respectively; a reversing valve having a first port, a second port, and a third port; wherein the first port is in communication with the oil tank, the second port is in communication with the rodless chamber, the first control valve group, and the second control valve group, respectively, and the third port is in communication with the rod chamber, the first control valve group, and the second control valve group, respectively; the reversing valve is a three-way ball valve; When the reversing valve is in the first position, the first port and the second port are connected, the third port is closed, and the oil in the oil tank flows into the rodless chamber. When the pressure of the rodless chamber and the pressure of the rod chamber reach a first preset ratio, the first control valve group is closed and the second control valve group is connected, and the oil in the rod chamber flows back to the oil tank, so that the piston rod extends. When the reversing valve is in the second position, the first port and the third port are connected, the second port is closed, and the oil in the oil tank enters the rod chamber. When the pressure of the rod chamber and the pressure of the rodless chamber reach a second preset ratio, the second control valve group is closed, the first control valve group is connected, and the oil in the rodless chamber flows back to the oil tank, so that the piston rod retracts. The first control valve group includes a first hydraulically controlled one-way valve and a first damping valve, and the second control valve group includes a second hydraulically controlled one-way valve and a second damping valve. The oil inlet of the first hydraulically controlled one-way valve is connected to the oil tank through the first damping valve, the oil outlet of the first hydraulically controlled one-way valve is connected to the rodless chamber and the second control oil port of the second hydraulically controlled one-way valve respectively, and the first control oil port of the first hydraulically controlled one-way valve is connected to the rod chamber and the oil outlet of the second hydraulically controlled one-way valve respectively; The oil inlet of the second hydraulically controlled one-way valve is connected to the oil tank through the second damping valve, the oil outlet of the second hydraulically controlled one-way valve is connected to the rod chamber and the first control oil port of the first hydraulically controlled one-way valve respectively, and the second control oil port of the second hydraulically controlled one-way valve is connected to the rodless chamber and the oil outlet of the first hydraulically controlled one-way valve respectively.

2. The self-lifting hydraulic control system for a transfer vehicle according to claim 1, characterized in that: Also includes: a first one-way valve, disposed downstream of the third port, wherein an oil outlet of the first one-way valve is in communication with the rod chamber; The second one-way valve is arranged downstream of the second port, and the oil outlet of the second one-way valve is communicated with the rodless cavity.

3. The self-lifting hydraulic control system for a transfer vehicle according to claim 2, characterized in that: It also includes a third one-way valve, which is arranged upstream of the rod chamber.

4. The self-lifting hydraulic control system for a transfer vehicle according to claim 1, characterized in that: A third damping valve is further provided upstream of the reversing valve.

5. The self-lifting hydraulic control system for a transfer vehicle according to claim 1, characterized in that: It also includes a relief valve, the oil inlet of the relief valve is communicated with the rod chamber, and the oil outlet of the relief valve is communicated with the oil tank.

6. The self-lifting hydraulic control system for a transfer vehicle according to any one of claims 1 to 5, characterized in that: Also included are a number of pressure monitors for detecting the pressure of the oil flowing into or out of each valve.

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