Oil cylinder control system

Abstract

The invention provides an oil cylinder control system which comprises an oil tank and an oil cylinder, and the ratio of the cross sectional area of a rodless cavity of the oil cylinder to the cross sectional area of a rod cavity of the oil cylinder is i1; an oil inlet and an oil return port of the reversing valve are directly or indirectly communicated with the oil tank, a first working oil port of the reversing valve is communicated with the rodless cavity, and a second working oil port of the reversing valve is communicated with the rod cavity; the ratio of the valve element area of the first working oil port to the valve element area of the second working oil port is i2; the flow control valve is respectively connected with the rodless cavity and the oil tank; when the reversing valve is located at a first station, the oil inlet is communicated with the second working oil port, the oil return port is communicated with the first working oil port, and the piston rod of the oil cylinder retracts; and when i1 is larger than i2 and the piston rod of the oil cylinder retracts, the flow control valve is opened. In this way, when the oil cylinder retracts, large pressure loss caused by oil return through the reversing valve is avoided, and then backpressure and oil inlet pressure of the system are prevented from being increased.

Description

Technical Field

[0001] The invention relates to the field of fluid transmission, and in particular to an oil cylinder control system. Background Art

[0002] In the related technology, a reversing valve is usually arranged in the hydraulic system, and the extension and retraction of the oil cylinder is achieved by changing the position of the reversing valve. However, due to the structural characteristics of the oil cylinder, the cross-sectional area of ​​the rodless chamber of the oil cylinder is larger than the cross-sectional area of ​​the rod chamber. Then, when the oil cylinder retracts, if the ratio of the cross-sectional area of ​​the rodless chamber and the rod chamber of the oil cylinder is larger than the valve core area ratio of the reversing valve, the return oil is equivalent to throttling when passing through the valve core of the reversing valve, which will cause a large pressure loss and require the oil inlet pressure to be greatly increased. Summary of the invention

[0003] The present invention is made to solve the above technical problems, and its purpose is to provide a cylinder control system that can reduce or avoid the increase of oil inlet pressure when return oil pressure loss occurs.

[0004] The present invention discloses an oil cylinder control system, comprising: an oil cylinder, wherein the ratio of the cross-sectional areas of a rodless chamber of the oil cylinder to a rod chamber of the oil cylinder is i1; a reversing valve, wherein an oil inlet and an oil return port of the reversing valve are directly or indirectly connected to the oil tank, a first working oil port of the reversing valve is connected to the rodless chamber, and a second working oil port of the reversing valve is connected to the rod chamber; a ratio of a valve core area of ​​the first working oil port to a valve core area of ​​the second working oil port is i2; a flow control valve, respectively connecting the rodless chamber and the oil tank; when the reversing valve is in a first working position, the oil inlet is connected to the second working oil port, the oil return port is connected to the first working oil port, and the piston rod of the oil cylinder retracts; when i1>i2, and the piston rod of the oil cylinder retracts, the flow control valve can be opened.

[0005] Optionally, when i1>i2 and the piston rod of the oil cylinder retracts, the flow control valve satisfies: Q′=(i1-i2)*Q, wherein Q′ is the return oil flow through the flow control valve, and Q is the inlet oil flow through the reversing valve.

[0006] In summary, when the oil cylinder retracts, the flow control valve releases the flow, which can reduce the pressure loss on the oil return side of the system. And by controlling the released flow of the flow control valve, the pressure loss on the oil return side of the system can be made consistent with that on the oil inlet side, that is, the pressure loss of the oil fluid from the first working oil port through the oil return port and through the flow control valve is equal to the pressure loss of the oil fluid from the oil inlet port through the second working oil port. Thus, when the oil cylinder of the system in this application retracts, regardless of the area ratio between the rodless chamber and the rod chamber in the oil cylinder and the spool area ratio in the reversing valve, a good match can be achieved, thereby avoiding a large pressure loss during oil return through the reversing valve when the oil cylinder retracts, and further avoiding an increase in back pressure and the oil inlet pressure of the system.

[0007] Optionally, it further includes a controller and an oil cylinder control valve. A plurality of oil cylinders are arranged in parallel, and the oil cylinder control valves correspond to the oil cylinders one by one. The oil cylinder control valve is arranged between one of the rodless chamber or the rod chamber and the fuel tank; the controller is respectively connected to the oil cylinder control valve and the flow control valve; the controller can control the opening and closing of the oil cylinder control valve, and control the oil return flow of the flow control valve according to the actuated oil cylinder; i1 is the ratio of the cross-sectional areas between the rodless chamber and the rod chamber of the oil cylinder corresponding to the opened oil cylinder control valve.

[0008] Optionally, when i1 ≤ i2 and the piston rod of the oil cylinder retracts, the flow control valve is disconnected.

[0009] Optionally, when the reversing valve is in the second working position, the oil inlet port communicates with the first working oil port of the reversing valve, the oil return port communicates with the second working oil port of the reversing valve, and the piston rod of the oil cylinder extends; when i1 < i2 and the piston rod of the oil cylinder extends, Δp′ = Δp / i1; where Δp is the pressure loss on the oil return side of the oil cylinder control system when the piston rod extends, and Δp′ is the pressure that needs to be increased on the oil inlet side of the oil cylinder control system when the piston rod extends. It can be seen that in order to compensate for the pressure loss on the oil return side, although the pressure on the oil inlet side needs to be increased, since the ratio i1 of the rod chamber to the rodless chamber is greater than 1, the pressure Δp / i1 that needs to be increased is small. That is to say, when the oil cylinder of this application system extends, a large increase in back pressure and the oil inlet pressure of the system can be avoided.

[0010] Optionally, when the piston rod of the oil cylinder extends, the flow control valve is disconnected.

[0011] Optionally, it further includes a balance valve. The first working oil port communicates with the rodless chamber through the balance valve, and / or the second working oil port communicates with the rod chamber through the balance valve.

[0012] Optionally, it also includes a shuttle valve and a differential pressure reducing valve, the oil inlet is connected to the oil tank through the differential pressure reducing valve, and the first working oil port is connected to the spring chamber of the differential pressure reducing valve through the shuttle valve, and the second working oil port is connected to the spring chamber of the differential pressure reducing valve through the shuttle valve.

[0013] In the present application, the shuttle valve is used to feed back the pressure of the first working oil port or the second working oil port to the spring chamber of the differential pressure reducing valve. Specifically, when the reversing valve is in the first position, the oil inlet is connected to the second working oil port, and the shuttle valve feeds back the pressure of the second working oil port to the spring chamber of the differential pressure reducing valve. When the reversing valve is in the second position, the oil inlet is connected to the first working oil port, and the shuttle valve feeds back the pressure of the first working oil port to the spring chamber of the differential pressure reducing valve. In this way, the pressure loss through the reversing valve core can be kept constant. At this time, the flow through the reversing valve is only related to the opening of the reversing valve and has nothing to do with the load.

[0014] By setting the differential pressure reducing valve, the pressure loss value of the reversing valve is fixed, which is equal to the spring pressure of the differential pressure reducing valve. Therefore, the oil inlet flow rate is only related to the opening of the reversing valve and has nothing to do with the load size, which facilitates the cylinder speed control.

[0015] Optionally, the reversing valve is a proportional reversing valve, which can switch to the first position or the second position when energized; when the reversing valve is not energized, it is in the cut-off position to disconnect the oil inlet from the first working oil port and the second working oil port.

[0016] Optionally, the flow control valve is a proportional speed regulating valve.

[0017] The beneficial effects of the present invention are as follows:

[0018] The present application discloses a cylinder control system, comprising: an oil tank and an oil cylinder, the ratio of the cross-sectional areas of the rodless chamber of the oil cylinder and the rod chamber of the oil cylinder being i1; a reversing valve, the oil inlet and the oil return port of the reversing valve being directly or indirectly connected to the oil tank, the first working oil port of the reversing valve being connected to the rodless chamber, and the second working oil port of the reversing valve being connected to the rod chamber; the ratio of the valve core area of ​​the first working oil port to the valve core area of ​​the second working oil port being i2; a flow control valve, respectively connecting the rodless chamber and the oil tank; when the reversing valve is in the first working position, the oil inlet is connected to the second working oil port, the oil return port is connected to the first working oil port, and the piston rod of the oil cylinder is retracted; when i1>i2, and the piston rod of the oil cylinder is retracted, the flow control valve can be opened.

[0019] Optionally, when i1>i2 and the piston rod of the oil cylinder retracts, the flow control valve satisfies: Q′=(i1-i2)*Q, wherein Q′ is the return oil flow through the flow control valve, and Q is the inlet oil flow through the reversing valve.

[0020] In summary, when the oil cylinder retracts, the flow is released through the flow control valve, which can reduce the pressure loss on the return oil side of the system, and by controlling the flow released by the flow control valve, the pressure loss on the return oil side of the system can be made consistent with the pressure loss on the oil inlet side, that is, the pressure loss of the oil from the first working oil port through the return oil port and the pressure loss through the flow control valve are equal to the pressure loss of the oil from the oil inlet through the second working oil port. In this way, on the first aspect, when the oil cylinder retracts, the system of the present application can have a good match regardless of the area ratio between the rodless cavity and the rod cavity in the oil cylinder and the area ratio of the valve core in the reversing valve, thereby avoiding a large pressure loss in the oil return through the reversing valve when the oil cylinder retracts, thereby avoiding an increase in the back pressure and the oil inlet pressure of the system; on the second aspect, ensuring the matching of the return oil pressure loss and the oil inlet pressure loss can make the oil cylinder move smoothly during the retraction process and avoid abnormalities such as shaking. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above features and advantages of the present invention can be better understood after reading the detailed description of the embodiments of the present disclosure in conjunction with the following drawings. In the drawings, the components are not necessarily drawn to scale, and components with similar related properties or features may have the same or similar reference numerals.

[0022] Figure 1 is a hydraulic system diagram of an embodiment of the present invention;

[0023] Figure 2 The present invention Figure 1 Schematic diagram of the cylinder when it is retracted;

[0024] Figure 3 The present invention Figure 1 Schematic diagram of the cylinder when extended;

[0025] Figure 4 It is a hydraulic system diagram of another embodiment of the present invention.

[0026] Description of reference numerals:

[0027] 10-Cylinder,

[0028] 11-rodless chamber, 12-rod chamber, 13-cylinder control valve,

[0029] 20-balance valve, 21-first balance valve, 22-second balance valve,

[0030] 40-Shuttle valve,

[0031] 50- Directional valve,

[0032] 51- oil inlet, 52- oil return port, 53- first working oil port, 54- second working oil port,

[0033] 60- Differential pressure reducing valve,

[0034] 70-Flow control valve. DETAILED DESCRIPTION

[0035] The present invention is further described below in conjunction with specific embodiments and drawings. More details are elaborated in the following description to facilitate a full understanding of the present invention. However, the present invention can obviously be implemented in a variety of other ways different from the description herein. Those skilled in the art can make similar generalizations and deductions based on actual application situations without violating the connotation of the present invention. Therefore, the protection scope of the present invention should not be limited by the content of this specific embodiment.

[0036] It should be noted that these and other subsequent drawings are only examples and are not drawn to scale, and should not be used to limit the actual scope of protection required by the present invention.

[0037] In the related technology, a reversing valve is usually set in the hydraulic system, and the extension and retraction of the oil cylinder is realized by changing the position of the reversing valve. However, due to the structural characteristics of the oil cylinder, the cross-sectional area of ​​the rodless chamber of the oil cylinder is larger than the cross-sectional area of ​​the rod chamber. When the oil cylinder retracts, if the ratio of the cross-sectional area of ​​the rodless chamber to the rod chamber of the oil cylinder is larger than the valve core area ratio of the reversing valve, the return oil is equivalent to throttling when passing through the reversing valve core, which will produce a large pressure loss and cause the oil inlet pressure to be greatly increased. Therefore, in order to solve this kind of problem, the technical solution of this application is produced, and the following is combined with Figure 1 to Figure 4 To elaborate.

[0038] like Figure 1 to Figure 3 As shown, the present application discloses an oil cylinder control system, including: an oil tank, an oil cylinder 10, a reversing valve 50 and a flow control valve 70. The oil cylinder 10 is an actuator of the system of the present application, and the oil cylinder 10 includes a cylinder body, a piston and a piston rod. The piston is movably arranged in the cylinder body, and the piston rod is installed on the piston. The piston divides the inner cavity of the cylinder body into a rod cavity 12 and a rodless cavity 11, wherein the side where the piston rod is located is the rod cavity 12, and the other side is the rodless cavity 11. Here, the ratio of the cross-sectional area between the rodless cavity 11 and the rod cavity 12 is set to i1.

[0039] The oil inlet 51 and the oil return port 52 of the reversing valve 50 are directly or indirectly connected to the oil tank, the first working oil port 53 of the reversing valve 50 is connected to the rodless chamber 11, and the second working oil port 54 of the reversing valve 50 is connected to the rod chamber 12; usually a power pump and a differential pressure reducing valve 60 described later are also arranged between the oil inlet 51 and the oil tank to realize indirect connection between the oil inlet 51 and the oil tank, the power pump can provide power to realize the flow of oil, and then realize the driving of the oil cylinder 10, while the oil return port 52 can be directly connected to the oil tank, and the ratio of the valve core area of ​​the first working oil port 53 to the valve core area of ​​the second working oil port 54 is set to i2.

[0040] The flow control valve 70 is connected to the rodless chamber 11 and the oil tank respectively; common types of flow control valves 70 include throttle valves, speed control valves, overflow throttle valves, flow dividing and collecting valves, and flow valves composed of these valves and check valves, travel valves, etc. In the present application, the flow control valve 70 is used to control the oil flow passing through itself, and then adjust the pressure loss on the return oil side of the system of the present application. Specifically, if the valve port of the flow control valve 70 is opened wide, the throttling pressure loss of the system return oil is reduced, and the return oil flow rate becomes larger; while if the valve port is closed narrowly, the return oil throttling leads to an increase in the return oil pressure loss, a decrease in the return oil flow rate, and an increase in the return oil back pressure.

[0041] The reversing valve 50 can realize the retraction of the piston rod of the oil cylinder 10 by switching its own position. Figure 2 As shown, when the reversing valve 50 is in the first position, the oil inlet 51 is connected to the second working oil port 54, the oil return port 52 is connected to the first working oil port 53, and the piston rod of the oil cylinder 10 is retracted.

[0042] From the above, it can be seen that when the cylinder 10 retracts, due to the characteristics of the cylinder itself, the oil inlet flow of the rod chamber 12 is smaller than the oil return flow of the rodless chamber 11. For example, if the oil inlet flow of the rod chamber 12 is Q, the oil return flow of the rodless chamber 11 is i1*Q.

[0043] When the piston rod of the oil cylinder 10 retracts, if i1<i2, the pressure loss on the system return oil side is less than the pressure loss on the system inlet oil side; if i1=i2, the pressure loss on the system return oil side is equal to the pressure loss on the system inlet oil side, and the flow control valve 70 does not need to release the flow, the flow control valve 70 is disconnected, and there is no need to divert the flow through one side of the flow control valve 70.

[0044] When i1>i2, the pressure loss on the system return oil side is greater than the pressure loss on the system inlet oil side, the flow control valve 70 can be opened, and the flow control valve 70 satisfies: Q′=(i1-i2)*Q; wherein Q′ is the return oil flow through the flow control valve 70, and Q is the oil inlet flow through the reversing valve 50, that is, the flow of oil from the oil inlet 51 through the second working oil port 54.

[0045] For example, assume that the area ratio i1 of the rodless chamber 11 to the rod chamber 12 is 2, and the ratio i2 of the spool area of the first working oil port 53 to the spool area of the second working oil port 54 is 1. When the oil cylinder 10 retracts, if the inlet oil flow rate is 100 L / min, the return oil flow rate will be twice that of the inlet oil, that is, the return oil flow rate is 2 * 100 = 200 L / min. To make the pressure loss of the return oil passing through the directional control valve 50 (i.e., the pressure loss when the oil fluid passes through the return oil port 52 from the first working oil port 53) and the pressure loss of the return oil passing through the flow control valve 70 equal to the pressure loss of the inlet oil passing through the directional control valve 50 (i.e., the pressure loss when the oil fluid passes through the second working oil port 54 from the inlet oil port 51), the flow rate released by the flow control valve 70 needs to be 200 - 100 = 100 L / min.

[0046] In summary, when the oil cylinder 10 retracts, by releasing the flow rate through the flow control valve 70, the pressure loss on the return oil side of the system can be reduced, and by controlling the flow rate released by the flow control valve 70, the pressure loss on the return oil side of the system can be made consistent with the pressure loss on the inlet oil side, that is, the pressure loss when the oil fluid passes through the return oil port 52 from the first working oil port 53 and the pressure loss through the flow control valve 70 are equal to the pressure loss when the oil fluid passes through the second working oil port 54 from the inlet oil port 51. In this way, on the one hand, when the oil cylinder 10 retracts in the system of the present application, regardless of the area ratio between the rodless chamber 11 and the rod chamber 12 in the oil cylinder 10 and the spool area ratio in the directional control valve 50, a good match can be achieved, thereby avoiding a large pressure loss when the return oil passes through the directional control valve 50 during the retraction of the oil cylinder 10, and further avoiding an increase in the back pressure and the inlet oil pressure of the system; on the other hand, ensuring the matching of the return oil pressure loss and the inlet oil pressure loss can enable the oil cylinder to move smoothly during the retraction process and avoid abnormalities such as jitter.

[0047] Optionally, the directional control valve 50 can realize the extension of the piston rod of the oil cylinder 10 by switching its own working position. Specifically, as Figure 3 shown, when the directional control valve 50 is in the second working position, the inlet oil port 51 is connected to the first working oil port 53, and the return oil port 52 is connected to the second working oil port 54, and the piston rod of the oil cylinder 10 extends.

[0048] When the piston rod of the oil cylinder 10 extends, if i1 > i2, the pressure loss of the return oil passing through the directional control valve 50 (i.e., the pressure loss generated when the oil fluid passes through the return oil port 52 from the second working oil port 54) is less than the pressure loss of the inlet oil (i.e., the oil fluid passes through the first working oil port 53 from the inlet oil port 51). If i1 = i2, the pressure loss of the return oil passing through the directional control valve 50 is equal to the pressure loss of the inlet oil. In these two cases, there is no need to increase the pressure on the inlet oil side.

[0049] If i1 < i2, then Δp′ = Δp / i1; where Δp is the pressure loss on the return oil side of the oil cylinder control system when the piston rod extends, and Δp′ is the pressure that needs to be increased on the inlet oil side of the oil cylinder control system when the piston rod extends. The pressure to be increased is realized by the power pump.

[0050] It can be seen that when i1 < i2, in order to compensate for the pressure loss on the oil return side, although the pressure on the oil inlet side needs to be increased, since the ratio i1 of the rod chamber 12 to the rodless chamber 11 is greater than 1, the pressure Δp / i1 that needs to be increased is small. That is to say, when the oil cylinder 10 of the present application extends, a large increase in the back pressure and the oil inlet pressure of the system can be avoided.

[0051] Optionally, as Figure 1 and Figure 3 shown, when the piston rod of the oil cylinder 10 extends, the flow control valve 70 does not need to work. Therefore, when the piston rod of the oil cylinder 10 extends, the flow control valve 70 is disconnected.

[0052] Optionally, it further includes a balance valve 20. The first working oil port 53 is connected to the rodless chamber 11 through the balance valve 20, and / or the second working oil port 54 is connected to the rod chamber 12 through the balance valve 20. The balance valve 20 can be a pressure-type balance valve, but other valve parts with similar functions such as a flow-type balance valve or a pilot-operated check valve can also be used instead. According to the actual different force conditions of the oil cylinder 10, the balance valve 20 can be provided only between the first working oil port 53 and the rodless chamber 11, or only between the second working oil port 54 and the rod chamber 12, or two balance valves 20 are provided and are respectively the first balance valve 21 and the second balance valve 22, and the first balance valve 21 is provided between the first working oil port 53 and the rodless chamber 11, and the second balance valve 22 is provided between the second working oil port 54 and the rod chamber 12. The setting of the balance valve 20 can achieve load holding, that is, ensure the smooth operation of the load and avoid sudden out-of-control.

[0053] Optionally, the oil cylinder control system further includes a shuttle valve 40 and a fixed-differential pressure reducing valve 60. The oil inlet 51 is connected to the fuel tank through the fixed-differential pressure reducing valve 60 and a power pump, and the first working oil port 53 is connected to the spring chamber of the fixed-differential pressure reducing valve 60 through the shuttle valve 40, and the second working oil port 54 is connected to the spring chamber of the fixed-differential pressure reducing valve 60 through the shuttle valve 40.

[0054] In the present application, the shuttle valve 40 is used to feedback the pressure of the first working oil port 53 or the second working oil port 54 to the spring chamber of the fixed-differential pressure reducing valve 60. Specifically, in combination with Figure 1 and Figure 2 it can be known that when the reversing valve 50 is in the first working position, the oil inlet 51 is connected to the second working oil port 54, and the shuttle valve 40 feedbacks the pressure of the second working oil port 54 to the spring chamber of the fixed-differential pressure reducing valve 60. And in combination with Figure 1 and Figure 3It can be seen that when the reversing valve 50 is in the second position, the oil inlet 51 is connected to the first working oil port 53, and the shuttle valve 40 feeds back the pressure of the first working oil port 53 to the spring chamber of the differential pressure reducing valve 60. In this way, the pressure loss through the valve core of the reversing valve 50 can be kept constant. At this time, the flow through the reversing valve 50 is only related to the opening of the reversing valve 50, and has nothing to do with the load.

[0055] By setting the differential pressure reducing valve 60, the pressure loss value of the reversing valve 50 is fixed, which is equal to the spring pressure of the differential pressure reducing valve 60, so that the oil inlet flow rate is only related to the opening of the reversing valve 50 and has nothing to do with the load size, which facilitates the speed control of the oil cylinder 10.

[0056] Optionally, the reversing valve 50 can be a proportional reversing valve 50, which can switch to the first position or the second position when the reversing valve 50 is energized; when the reversing valve 50 is not energized, it is in the cut-off position to disconnect the oil inlet 51 from the first working oil port 53 and the second working oil port 54, and the system no longer works.

[0057] Optionally, the flow control valve 70 is a proportional speed regulating valve, and the return oil flow rate and the return oil pressure loss are adjusted by adjusting the valve port size of the flow control valve 70 .

[0058] Figure 4 It is a hydraulic system diagram of another embodiment of the present invention, multiple cylinders 10 can be arranged in parallel, and a cylinder control valve 13 is set between one of the rodless chamber 11 or the rod chamber 12 and the oil tank to control the movement of the cylinder 10 by turning on and off the cylinder control valve 13; at the same time, the cylinder control system is also provided with a controller to respectively connect each cylinder control valve 13 and the flow control valve 70, so that the movement of any cylinder 10 can be controlled individually by the controller, and the return oil flow of the flow control valve 70 can be adjusted to match the cylinder 10 in action. At this time, i1 is the ratio of the cross-sectional area between the rodless chamber 11 and the rod chamber 12 in the cylinder 10 corresponding to the opened cylinder control valve 13.

[0059] For example, the cylinder control valve 13 can be arranged between the rod chamber 12 and the second balance valve 22. Three cylinders 10 are arranged in parallel, namely #1 cylinder, #2 cylinder and #3 cylinder. The ratio of the cross-sectional area between the rodless chamber 11 and the rod chamber 12 in the #1 cylinder is i1. #1 , the ratio of the cross-sectional area between the rodless chamber 11 and the rod chamber 12 in the #2 oil cylinder is i1 #2 , the ratio of the cross-sectional area between the rodless chamber 11 and the rod chamber 12 in the #3 oil cylinder is i1 #3 The cylinder control valves 13 correspond to the cylinders 10 one by one, namely #1 cylinder control valve, #2 cylinder control valve and #3 cylinder control valve.

[0060] When the #1 oil cylinder is required to move, the controller controls the #1 oil cylinder control valve to open, and adjusts the return oil flow of the flow control valve 70 to meet the following conditions:

[0061] Q′ #1 =(i1 #1 -i2)*Q;

[0062] When the #2 oil cylinder is required to move, the controller controls the #2 oil cylinder control valve to open, and adjusts the return oil flow of the flow control valve 70 to meet the following conditions:

[0063] Q′ #2 =(i1 #2 -i2)*Q;

[0064] When the #3 oil cylinder is required to move, the controller controls the #3 oil cylinder control valve to open, and adjusts the return oil flow of the flow control valve 70 to meet the following conditions:

[0065] Q′ #3 =(i1 #3 -i2)*Q;

[0066] In this way, the hydraulic system of the present application can independently control the action of any one of the multiple cylinders 10, and adjust the return oil flow of the flow control valve 70 according to the actuated cylinder 10, so that the pressure loss on the return oil side of the system and the pressure loss on the oil inlet side are always consistent, thereby improving the intelligence of the system.

[0067] Although the present invention is disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, any modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope defined by the claims of the present invention.

Claims

1. A cylinder control system, characterized in that: Comprising: An oil cylinder (10), the ratio of the cross-sectional area between the rodless chamber (11) and the rod chamber (12) of the oil cylinder (10) being i1; A directional control valve (50), the oil inlet (51) and the oil return port (52) of the directional control valve (50) being directly or indirectly connected to the fuel tank, the first working oil port (53) of the directional control valve (50) being connected to the rodless chamber (11), and the second working oil port (54) of the directional control valve (50) being connected to the rod chamber (12); the ratio of the spool area of the first working oil port (53) to the spool area of the second working oil port (54) being i2; A flow control valve (70), respectively connected to the rodless chamber (11) and the fuel tank; When the directional control valve (50) is in the first working position, the oil inlet (51) is connected to the second working oil port (54), the oil return port (52) is connected to the first working oil port (53), and the piston rod of the oil cylinder (10) retracts; When i1 > i2 and the piston rod of the oil cylinder (10) retracts, the flow control valve (70) opens.

2. The oil cylinder control system according to claim 1, when i1 > i2 and the piston rod of the oil cylinder (10) retracts, the flow control valve (70) satisfies: Q′ = (i1 - i2) * Q in, Q′ is the oil return flow rate through the flow control valve (70), and Q is the oil inlet flow rate through the directional control valve (50).

3. The oil cylinder control system according to claim 2, further comprising a controller and an oil cylinder control valve (13), a plurality of the oil cylinders (10) being arranged in parallel, the oil cylinder control valve (13) corresponding to the oil cylinder (10) one by one, and the oil cylinder control valve (13) being arranged between one of the rodless chamber (11) or the rod chamber (12) and the fuel tank; the controller is respectively connected to the oil cylinder control valve (13) and the flow control valve (70); The controller can control the opening and closing of the oil cylinder control valve (13), and control the oil return flow rate of the flow control valve (70) according to the operating oil cylinder (10); i1 is the ratio of the cross-sectional area between the rodless chamber (11) and the rod chamber (12) of the oil cylinder (10) corresponding to the opened oil cylinder control valve (13).

4. The oil cylinder control system according to claim 1, characterized in that: When i1 ≤ i2 and the piston rod of the oil cylinder (10) retracts, the flow control valve (70) disconnects.

5. The oil cylinder control system according to claim 1, characterized in that: When the directional control valve (50) is in the second working position, the oil inlet (51) is connected to the first working oil port (53) of the directional control valve (50), the oil return port (52) is connected to the second working oil port (54) of the directional control valve (50), and the piston rod of the oil cylinder (10) extends; When i1 < i2 and the piston rod of the oil cylinder (10) extends, Δp′ = Δp / i1; where Δp is the pressure loss on the oil return side of the oil cylinder control system when the piston rod extends, and Δp′ is the pressure that needs to be increased on the oil inlet side of the oil cylinder control system when the piston rod extends.

6. The oil cylinder control system according to claim 5, characterized in that: When the piston rod of the oil cylinder (10) is extended, the flow control valve (70) is disconnected.

7. The oil cylinder control system according to claim 1, characterized in that: It also includes a balancing valve (20), wherein the first working oil port (53) is connected to the rodless chamber (11) through the balancing valve (20), and / or the second working oil port (54) is connected to the rod chamber (12) through the balancing valve (20).

8. The oil cylinder control system according to claim 5, characterized in that: It also includes a shuttle valve (40) and a differential pressure reducing valve (60), The oil inlet (51) is connected to the oil tank via the differential pressure reducing valve (60), and, The first working oil port (53) is connected to the spring chamber of the differential pressure reducing valve (60) through the shuttle valve (40), and, The second working oil port (54) is connected to the spring chamber of the differential pressure reducing valve (60) through the shuttle valve (40).

9. The oil cylinder control system according to claim 5, characterized in that: The reversing valve (50) is a proportional reversing valve (50). When the reversing valve (50) is energized, it can switch to the first working position or the second working position; When the reversing valve (50) is not powered, it is in a cut-off position so that the oil inlet (51) is disconnected from the first working oil port (53) and the second working oil port (54).

10. The oil cylinder control system according to claim 5, characterized in that: The flow control valve (70) is a proportional speed regulating valve.

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