A control method and valve control system for a cylinder with high stability

Abstract

The application discloses a control method and a valve control system with high stability of oil cylinder movement, and relates to the field of oil cylinder movement control. The system comprises a return oil pipeline and an oil inlet pipeline for connecting an oil cylinder and an oil station. At least two control valves are connected in parallel on the return oil pipeline, and the allowable flow of each control valve is different. The allowable flow is the maximum flow allowed by the control valve to pass through liquid oil. The sum of the allowable flows of all the control valves is equivalent to the maximum flow of liquid oil required when the oil cylinder drives the load to move. The method can be applied to the system, that is, at least two control valves are connected in parallel on the liquid oil return pipeline when the oil cylinder drives the load to move. The application effectively solves the adaptability problem of the balance valve to the flow requirement in the use of the balance valve in the oil cylinder movement control, and improves the stability of the oil cylinder movement.

Description

Technical Field

[0001] This invention relates to the field of hydraulic cylinder motion control, and in particular to a control method and valve control system for hydraulic cylinder motion with high stability. Background Technology

[0002] As is well known, hydraulic cylinder 1 has a rod chamber and a rodless chamber. Oil enters the rod chamber and returns oil to the rodless chamber, enabling the retraction motion of hydraulic cylinder 1. Oil enters the rodless chamber and returns oil to the rod chamber, enabling the extension motion of hydraulic cylinder 1. The movement of hydraulic cylinder 1 is manifested externally as the output of pushing and pulling force (pushing and pulling the load) and speed (the load moves at a set speed). With technological advancements, the stability requirements for the movement of hydraulic cylinder 1 are becoming increasingly stringent. Under certain operating conditions, for ease of explanation, the oil-inlet chamber is referred to as oil inlet chamber 12, and the oil-return chamber is referred to as oil return chamber 11.

[0003] To achieve high stability in the movement of cylinder 1, the following control methods are currently available (for ease of explanation, the pipeline connecting oil station 2 or the oil supply valve (collectively referred to as "oil station 2") to oil inlet chamber 12 is called oil inlet pipeline 3, and the pipeline connecting oil station 2 to oil return chamber 11 is called oil return pipeline 4. Taking the rodless chamber as the oil return chamber 11 and the rod chamber as the oil inlet chamber 12, with cylinder 1 retracting and moving with a load as an example, the specific methods are as follows:) The first control method: such as Figure 1 As shown, a hydraulically controlled check valve 5 and a relief valve 6 are added to the return oil line 4. The hydraulically controlled check valve 5 and the relief valve 6 are connected in parallel, and the pilot chamber of the hydraulically controlled check valve 5 is connected to the inlet oil line 3. When the cylinder 1 retracts and moves with the load, the hydraulic oil pressure in the inlet oil line 3 will act on the pilot chamber of the hydraulically controlled check valve 5, causing the hydraulically controlled check valve 5 to open. The hydraulic oil in the rodless chamber can flow back to the oil station 2 through the hydraulically controlled check valve 5. The relief valve 6 plays a protective role. This control method is mainly used for oil circuit locking control and is not suitable for smooth motion control or load override control (if it must be used, the cylinder 1 or the machine / equipment (hereinafter referred to as the machine) will experience severe vibration).

[0004] The second control method: such as Figure 2 As shown, a balance valve 7 is added to the return oil line 4, and the pilot chamber of the balance valve 7 is connected to the inlet oil line 3; when the cylinder 1 retracts and moves with the load, as... Figure 2As shown, oil station 2 supplies oil to the rod chamber. At this time, the one-way valve core 72 of the balance valve 7 is locked, and the oil cannot flow through the one-way valve core 72. The oil pressure in the oil inlet pipeline 3 will act on the pilot chamber of the balance valve 7, causing the sequence valve core 71 of the balance valve 7 to open. The oil in the rodless chamber can flow back to oil station 2 through the sequence valve core 71 of the balance valve 7. This method is currently the most commonly used control method. However, because the valve port size of the sequence valve core 71 is fixed and the flow rate is not adjustable, it also has shortcomings. The specific shortcomings are as follows: First, if the selected balance valve 7 has too large a flow capacity, the hydraulic system will still experience overshoot, causing severe machine vibration. Second, it is not very suitable for applications with variable speed requirements during operation; the balance valve 7 is only suitable for hydraulic systems with a relatively constant speed. Third, the specifications of the balance valve 7 are generally increased in multiples according to the flow rate. Therefore, the specifications of the balance valve 7 are difficult to meet the flow rate requirements of systems with a difference between two specifications (if a larger flow rate specification is selected, the system will vibrate; if a smaller flow rate specification is selected, the speed requirement cannot be met).

[0005] The third control method, such as Figure 3 As shown, a variable throttle balance valve 7 is added to the return oil line 4 (to distinguish it from the "balance valve 7" in the "second control method", the variable throttle balance valve 7 is called the "pressure-type variable valve 8"). The difference between the pressure-type variable valve 8 and the "balance valve 7" in the "second control method" is that the opening of the sequence valve core 71 is adjustable, and its opening is only related to the pressure at the pressure port (X port) of the pilot chamber, and is not related to the load. The pressure-type variable valve 8 has an overflow valve core 82, which is connected to the overflow port (T port) to avoid overpressure of the liquid oil in the return oil line 4. Although this method is suitable for applications where the cylinder 1 requires variable speed (by precisely changing the pressure at port X, the opening of the sequence valve core 71 can be precisely controlled, and the oil supply can be precisely controlled in conjunction with precise control of the oil supply (which can be achieved with a practical proportional valve), the speed of the load movement can be precisely controlled), it also has the shortcomings of the second control method. Specifically, there are fewer pressure-type variable valve 8 specifications, and the adaptability to flow requirements is worse (there are no available balance valve 7 specifications for flow requirements at the differential point or for large flow requirements).

[0006] In summary, given the limited range of valve flow specifications currently available, a new control method is needed to improve the stability of cylinder movement. Summary of the Invention

[0007] The purpose of this invention is to provide a control method and valve control system with high stability of hydraulic cylinder movement, which effectively solves the problem of the adaptability of the balancing valve to the flow demand when using the balancing valve in hydraulic cylinder movement control, and improves the stability of hydraulic cylinder movement.

[0008] The technical solution adopted in this invention is as follows: a valve control system with high stability of cylinder movement, including a return oil line and an inlet oil line for connecting the cylinder and the oil station; at least two control valves are connected in parallel on the return oil line, each control valve has a different allowable flow rate, the allowable flow rate is the maximum flow rate of liquid oil allowed to pass through the control valve; the sum of the allowable flow rates of all control valves is equivalent to the maximum flow rate of liquid oil required when the cylinder drives the load movement.

[0009] Furthermore, the control valve is one or more of a pilot-operated sequence valve, a balance valve, and a pressure-type variable valve, and the type and number of control valves are selected according to the operating conditions of the hydraulic cylinder.

[0010] Furthermore, if the operating condition requirement of the return oil line is "high flow rate during return oil and low flow rate during inlet oil", then at least one pilot-operated sequence valve must be present in the control valve. The pilot chamber of the pilot-operated sequence valve is connected to the inlet oil line through the first pilot line. The remaining control valves are balance valves and / or pressure-type variable valves. The pilot chamber of the balance valve is connected to the inlet oil line through the second pilot line.

[0011] Furthermore, if the operating condition requirement of the return oil line is "high flow rate during both return and inlet oil", then the control valve consists of a balance valve and / or a pressure-type variable valve, and the pilot chamber of the balance valve is connected to the inlet oil line through a second pilot line.

[0012] Furthermore, if the operating condition requirement of the return oil pipeline is "stepless adjustment of oil flow", then at least one pressure-type variable valve must be present in the control valve.

[0013] A method for controlling the motion of a hydraulic cylinder with high stability includes the following steps: S1: At least two control valves are connected in parallel on the return oil line of the cylinder under load. Each control valve has a different allowable flow rate. The allowable flow rate is the maximum flow rate of hydraulic oil that the control valve allows to pass through. The sum of the allowable flow rates of all control valves is equivalent to the maximum flow rate of hydraulic oil required by the cylinder when it is in motion. S2: When the hydraulic cylinder drives the load to move, some or all of the control valves are opened in sequence according to the order of allowable flow from small to large. The oil return chamber in the hydraulic cylinder is called the oil return chamber, and the oil inlet chamber in the hydraulic cylinder is called the oil inlet chamber. The liquid oil in the oil return chamber flows back to the oil station through the oil return circuit, and the liquid oil in the oil station enters the oil inlet chamber through the oil inlet pipe.

[0014] Furthermore, the valve control system described above exhibits high stability in the movement of the hydraulic cylinder.

[0015] Furthermore, if the load movement is the retraction movement of the hydraulic cylinder, then the return oil line in the valve control system is connected between the rodless chamber and the oil station as the return oil line, and the inlet oil line in the valve control system is connected between the rod chamber and the oil station as the inlet oil line; if the load movement is the extension movement of the hydraulic cylinder, then the return oil line in the valve control system is connected between the rod chamber and the oil station as the return oil line, and the inlet oil line in the valve control system is connected between the rodless chamber and the oil station as the inlet oil line.

[0016] Furthermore, if the operating condition requirement of the return oil pipeline is "high flow rate during return oil and low flow rate during inlet oil", the control method includes steps A1-A3: A1: Liquid oil in the gas station enters the oil inlet chamber through the oil inlet pipeline; A2: The hydraulic pressure in the inlet pipeline acts on the pilot chamber of the pilot-operated sequence valve on the return pipeline through the first pilot pipeline, and the pilot-operated sequence valve opens; the oil pressure in the return chamber also flows back to the oil station through the pilot-operated sequence valve. A3: The hydraulic pressure in the inlet pipeline acts on the pilot chamber of the balance valve through the second pilot pipeline, and the sequential valve core of the balance valve opens; or / and the pressure-type variable valve obtains external pressure from port X, and the variable valve core of the pressure-type variable valve opens; the hydraulic pressure in the return oil chamber flows back to the oil station through the sequential valve core of the balance valve or / and the variable valve core of the pressure-type variable valve. If the operating condition requirement of the return oil pipeline is "high flow rate during both return and inlet oil", the control method includes steps B1-B2: B1: Liquid oil in the gas station enters the inlet chamber through the inlet pipeline; B2: The hydraulic pressure in the inlet pipeline acts on the pilot chamber of the balance valve through the second pilot pipeline, and the sequential valve core of the balance valve opens; or / and the pressure-type variable valve obtains external pressure from port X, and the variable valve core of the pressure-type variable valve opens; the hydraulic oil in the return oil chamber flows back to the oil station through the sequential valve core of the balance valve or / and the variable valve core of the pressure-type variable valve.

[0017] Furthermore, increasing the external pressure increases the opening degree of the variable valve core of the pressure-type variable valve, increases the flow rate of the hydraulic oil, and increases the movement speed of the hydraulic cylinder; decreasing the external pressure decreases the opening degree of the variable valve core of the pressure-type variable valve, decreases the flow rate of the hydraulic oil, and decreases the movement speed of the hydraulic cylinder.

[0018] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. This invention connects multiple control valves in parallel, allowing the allowable flow rates of the multiple control valves to be superimposed, thereby adapting to the requirement of a large flow rate of hydraulic oil when the cylinder is in motion; 2. In this invention, the allowable flow rates of the control valves are all different, that is, the allowable flow rates between the control valves are in a relationship of increasing or decreasing. The control valves are opened one after another in the order of increasing allowable flow rates, so that the hydraulic oil flow control is more precise, thereby making the retraction movement of the oil cylinder more stable. This is especially evident when the retraction movement is started, and when the oil cylinder is impacted and retraction movement occurs, which can effectively avoid the vibration of the oil cylinder or machine / equipment (hereinafter referred to as the machine) and ensure the safe operation of the machine. 3. This invention addresses the situation where the flow rate specifications of existing control valves cannot be changed, and the flow rate specifications of existing balance valves cannot meet the flow rate requirements during cylinder movement. By connecting multiple control valves with different flow rates in parallel, multi-level control and variable speed control can be achieved. This satisfies the speed requirements of retraction movement and avoids machine vibration, thus having a wider range of applications. Attached Figure Description

[0019] The present invention will be described by way of example and with reference to the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the first control method in the background technology; Figure 2 This is a schematic diagram of the second control method in the background art; Figure 3 This is a schematic diagram of the third control method in the background art; Figure 4 This is a schematic diagram illustrating the working conditions required by the hydraulic cylinder in the first type of return oil pipeline disclosed in this invention to drive the load. Figure 5 This is a schematic diagram illustrating the working conditions required by the hydraulic cylinder in the first type of return oil pipeline disclosed in this invention, in order to drive the load. Figure 6 This is a schematic diagram illustrating the working conditions required for the hydraulic cylinder to retract in order to drive the load in the second type of return oil pipeline disclosed in this invention. Figure 7 This is a schematic diagram illustrating the working conditions required by the hydraulic cylinder in the second type of return oil pipeline disclosed in this invention, in order to drive the load. Figure 8 This is a schematic diagram illustrating the operating conditions required by the hydraulic cylinder in the third type of return oil pipeline disclosed in this invention, in order to drive the load. Figure 9 This is a schematic diagram illustrating the operating conditions required by the hydraulic cylinder to extend in order to drive the load in the third type of return oil pipeline disclosed in this invention. Figure 10 This is a schematic diagram illustrating the working condition requirement of the fourth type of return oil pipeline disclosed in this invention, in which the hydraulic cylinder needs to retract to drive the load. Figure 11This is a schematic diagram illustrating the operating conditions of the fourth type of return oil pipeline disclosed in this invention, in which the hydraulic cylinder needs to extend to drive the load. The markings in the diagram are: 1-oil cylinder; 2-oil station; 3-oil inlet line; 4-oil return line; 5-hydraulic control check valve; 6-relief valve; 7-balance valve; 71-sequence valve core; 72-check valve core; 73-second pilot line; 8-pressure variable valve; 81-variable valve core; 82-relief valve core; 9-pilot-operated sequence valve; 91-first pilot line; 10-load; 11-oil return chamber; 12-oil inlet chamber. Detailed Implementation

[0020] In the description of this specification, it should be noted that if terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," or "outer" appear to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use, they are only for the convenience of describing this specification and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this specification.

[0021] Furthermore, the use of terms such as "horizontal" or "vertical" in this specification does not imply that the component must be absolutely horizontal or suspended, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0022] In the description of this specification, it should also be noted that, unless otherwise expressly specified and limited, the terms “set up,” “install,” “connect,” and “link” should be interpreted broadly. For example, a link can be a fixed link, a detachable link, or an integral link; it can be a mechanical link or an electrical link; it can be a direct link or an indirect link through an intermediate medium; it can be a connection within two components.

[0023] It should be noted that, under certain operating conditions, for ease of explanation, the oil inlet chamber is referred to as the oil inlet chamber, and the oil return chamber is referred to as the oil return chamber.

[0024] Example 1 like Figures 4-11 As shown, a valve control system with high stability of cylinder movement includes a return oil line 4 and an inlet oil line 3 for connecting cylinder 1 and oil station 2; at least two control valves are connected in parallel on the return oil line 4, each control valve has a different allowable flow rate, the allowable flow rate is the maximum flow rate of liquid oil allowed through the control valve; the sum of the allowable flow rates of all control valves is equivalent to the maximum flow rate of liquid oil required when cylinder 1 drives load 10 to move.

[0025] Specifically, such as Figure 4 , 6 8, 10, when cylinder 1 needs to retract to drive load 10, the return oil line 4 in the valve control system is connected to the rodless chamber in cylinder 1, and the oil in the rodless chamber flows back to oil station 2 through the return oil line 4; Figure 5 , 7 9, 11. When the hydraulic cylinder 1 needs to extend to drive the load 10, the return oil line 4 in the valve control system is connected to the rod chamber of the hydraulic cylinder 1, and the oil in the rod chamber flows back to the oil station 2 through the return oil line 4. When the hydraulic cylinder 1 needs to reciprocate to drive the load 10 to move (such as driving the load 10 to swing), the connection position of the return oil line 4 alternates between the rod chamber and the rodless chamber. In summary, the return oil line 4 is always connected to the return oil chamber 11 that drives the load 10 to move.

[0026] In this embodiment, by connecting multiple control valves in parallel, the allowable flow rates of the multiple control valves can be superimposed, thereby meeting the requirement of high hydraulic oil flow rate when the cylinder 1 is in motion. On the other hand, multi-level control is achieved, initially realizing variable speed control, which not only meets the speed requirements of the cylinder 1 carrying the load 10, but also avoids machine vibration, thus having a wider range of applications. When the cylinder 1 carries the load 10, the control valves are opened sequentially according to the order of allowable flow rate from small to large, so that the hydraulic oil flow rate gradually increases, thereby making the movement of the cylinder 1 carrying the load 10 more stable, especially at the start of the movement and when the cylinder 1 is subjected to impact and vibrates. This not only meets the speed requirements of the movement, but also effectively avoids the vibration of the cylinder 1 or the machine / equipment (hereinafter collectively referred to as the machine), ensuring the safe operation of the machine.

[0027] Specifically, in this embodiment, the maximum flow rate of hydraulic oil required for cylinder 1 to move is b, and the allowable flow rates of all control valves are a(1), a(2), a(3)...a(n), and a(1) < a(2) < a(3)...a(n-1) < a(n), where n is the number of control valves; then the value of b should satisfy a(1) < b ≤ a(1) + a(2) + a(3)...a(n-1) + a(n), especially the case where b ≠ a(1), a(2), a(3)...a(n); if the number of control valves is 2, i.e. n=2; the maximum flow rate of hydraulic oil required for cylinder 1 to move is b=200L / min or 120L / min; then two control valves with flow rate specifications (allowable flow rates) of a(1)=40L / min and a(2)=160L / min can be selected, of course, other choices also exist. The specific control is as follows.

[0028] When the hydraulic cylinder 1 moves with the load 10, the liquid oil in the oil station 2 enters the oil inlet chamber 12 through the oil inlet pipe 3; on the return oil pipe 4, the control valve with an allowable flow rate of a(1) is first opened to allow the return oil chamber 11 to return oil at a small flow rate; if the return oil flow rate of the return oil chamber 11 continues to increase, the control valve with an allowable flow rate of a(2) is opened to allow the return oil chamber 11 to return oil at a large flow rate, where the flow rate value a(1) is less than the flow rate value a(2). It can be known that the movement of the hydraulic cylinder 1 can achieve two levels of control, namely 40L / min and 160L / min+40L / min=200L / min. It can be further determined that, since there is a pre-existing small flow rate return oil on the return oil pipe 4, the movement of the hydraulic cylinder 1 is more stable when the movement starts and when the hydraulic cylinder 1 is impacted, thereby avoiding the occurrence of shaking and ensuring the safe operation of the load 10. At the same time, compared with the control of only the control valve with an allowable flow rate of a(1) or a(2), this valve control system can meet the requirements of speed and flow rate.

[0029] Of course, on the other hand, if the control cylinder 1 is reset, that is, the cylinder 1 does not carry the load 10 and moves in the opposite direction to the load 10, such as when the cylinder 1 retracts, it carries the load 10, that is, when the cylinder 1 is reset, it extends. According to the actual working conditions, one or two control valves can be opened to realize a small flow rate (a(1)=40L / min or a(2)=160L / min) of oil in the rodless chamber, or a large flow rate (40L / min+160L / min=200L / min) of oil in the rodless chamber; the liquid oil in the rod chamber flows back to the cylinder 1 through the rod chamber pipeline, so that the extension movement of the cylinder 1 can be controlled.

[0030] In this embodiment, the control valve is one or more of the following: a pilot-operated sequence valve 9, a balance valve 7, and a pressure-type variable valve 8. The type and number of control valves are selected according to the operating conditions of the cylinder 1. The pilot-operated sequence valve 9, the balance valve 7, and the pressure-type variable valve 8 are all valve bodies commonly used by those skilled in the art, and their specific structures will not be described in detail in this specification. It should be noted that the pilot-operated sequence valve 9 has a pilot chamber. When the pilot chamber is subjected to sufficient pressure, the valve core of the pilot-operated sequence valve 9 can be opened, and the hydraulic oil can flow. The balance valve 7 also has a pilot chamber. When the pilot chamber is subjected to sufficient pressure, the sequence valve core 71 of the balance valve 7 can be opened, and the hydraulic oil can flow through the sequence valve core 71. The difference between the balance valve 7 and the pilot-operated sequence valve 9 is that the balance valve 7 also has a one-way valve core 72. The pressure-type variable valve 8 also has a pilot chamber. The opening degree of the variable valve core 81 of the pressure-type variable valve 8 is positively correlated with the pressure port (X port) of the pilot chamber. The operating conditions of the flow demand in the return oil line 4 are detailed below.

[0031] It should be noted that the opening pressure of a control valve with a smaller allowable flow rate is also lower than that of a control valve with a larger allowable flow rate, in order to ensure that the control valve opens sequentially.

[0032] It should be noted that the pressure-type variable valve 8 has an overflow valve core 82, which is connected to the overflow port (T port) to prevent the oil pressure in the rodless chamber pipeline from overpressure.

[0033] Example 2 Based on Example 1, further feasible implementation methods are proposed.

[0034] like Figures 4-5 , Figures 8-9 As shown, the operating condition requirement of the first type of return oil line 4 is "large flow rate during return oil and small flow rate during inlet oil". This operating condition corresponds to two implementation methods. The first implementation method is that the cylinder 1 needs to retract to drive the load 10. The second implementation method is that the cylinder 1 needs to extend to drive the load 10. The only difference between the two cases is that the return oil line 4 is connected to the chamber on the cylinder 1. The principle and control method are the same. To simplify the text, the first implementation method "the cylinder 1 needs to retract to drive the load 10" is used as an example for explanation. That is, the return oil line 4 is connected to the rodless chamber and the inlet oil line 3 is connected to the rod chamber, as detailed below.

[0035] like Figure 4 , Figure 8 As shown, the control valve must include at least one pilot-operated sequence valve 9. The pilot chamber of the pilot-operated sequence valve 9 is connected to the oil inlet pipe 3 through the first pilot pipe 91. When oil returns from the rodless chamber (return chamber 11) (the cylinder 1 carries the load 10 and moves), the hydraulic pressure in the oil inlet pipe 3 is used to activate the opening of the pilot-operated sequence valve 9. The remaining control valves are a balance valve 7 and / or a pressure-type variable valve 8. The pilot chamber of the balance valve 7 is connected to the oil inlet pipe 3 through the second pilot pipe 73. When oil returns from the rodless chamber (return chamber 11), the hydraulic pressure in the oil inlet pipe 3 is used to activate the opening of the sequence valve core 71 of the balance valve 7. The opening of the pressure-type variable valve 8 is provided by an external source. In this operating condition, when oil is entering the rodless chamber (return chamber 11) (the cylinder 1 is not moving with the load 10), the pilot-operated sequence valve 9 is closed and cannot flow oil. Only other control valves are open to allow oil flow, such as the one-way valve core 72 of the balance valve 7, which allows oil flow; or / and the variable valve core 81 of the pressure-type variable valve 8 opens when subjected to external pressure, thus satisfying the requirement of "small flow rate when entering the oil". When oil is returning from the rodless chamber (return chamber 11) (the cylinder 1 is moving with the load 10), the pilot-operated sequence valve 9 and the sequence valve core 71 of the balance valve 7 can open under the linkage of the oil pressure in the oil inlet pipe 3. When the X port of the pressure-type variable valve 8 is subjected to external pressure, its variable valve core 81 can open. Therefore, all control valves can flow when oil returns from the rodless chamber, satisfying the requirement of "large flow rate when retracting".

[0036] like Figure 5 , Figure 9 As shown, based on the above control principle that the cylinder 1 moves with the load 10 through the retraction motion and the rodless chamber acts as the return oil chamber 11, it can be deduced that the cylinder 1 moves with the load 10 through the extension motion and the rod chamber acts as the return oil chamber 11.

[0037] It should be noted that, according to the above description, "when the hydraulic cylinder 1 needs to perform reciprocating motion to drive the load 10 to move (such as driving the load 10 to swing), the connection position of the return oil line 4 alternates between the rod chamber and the rodless chamber." When the hydraulic cylinder 1 performs reciprocating motion to drive the load 10, the connection position of the return oil line 4 is switched accordingly. Based on the control principle of the rodless chamber and the rod chamber as the return oil chamber 11, stable control of the hydraulic cylinder 1 performing reciprocating motion to drive the load 10 can be achieved.

[0038] like Figures 6-7 , Figures 10-11 As shown, the operating condition requirement of the second type of return oil line 4 is "high flow rate during both return and inlet oil". This operating condition corresponds to two implementation methods. The first implementation method is that the cylinder 1 needs to retract to drive the load 10, and the second implementation method is that the cylinder 1 needs to extend to drive the load 10. The only difference between the two cases is that the return oil line 4 is connected to the chamber on the cylinder 1. The principle and control method are the same. To simplify the text, the first implementation method "the cylinder 1 needs to retract to drive the load 10" is used as an example for explanation. That is, the return oil line 4 is connected to the rodless chamber, and the inlet oil line 3 is connected to the rod chamber, as detailed below.

[0039] like Figure 6 , Figure 10 The control valve consists of a balance valve 7 and / or a pressure-type variable valve 8. The pilot chamber of the balance valve 7 is connected to the oil inlet pipe 3 through the second pilot pipe 73. When oil returns in the rodless chamber (return oil chamber 11), the hydraulic oil pressure in the oil inlet pipe 3 is used to link the opening of the sequential valve core 71 of the balance valve 7. Regardless of whether oil is entering in the rodless chamber (return oil chamber 11) (when the cylinder 1 is not moving with the load 10) or returning in the rodless chamber (return oil chamber 11) (when the cylinder 1 is moving with the load 10), all control valves can be supplied with hydraulic oil, thus satisfying the requirement that "the hydraulic oil flow is large during both retraction and extension movements".

[0040] like Figure 7 , Figure 11 It should be noted that, similarly, based on the above control principle that the cylinder 1 moves with the load 10 through the retraction movement and the rodless chamber acts as the return oil chamber 11, it can be inferred that the cylinder 1 moves with the load 10 through the extension movement and the rod chamber acts as the return oil chamber 11.

[0041] It should be noted that, according to the above description, "when the hydraulic cylinder 1 needs to perform reciprocating motion to drive the load 10 to move (such as driving the load 10 to swing), the connection position of the return oil line 4 alternates between the rod chamber and the rodless chamber." When the hydraulic cylinder 1 performs reciprocating motion to drive the load 10, the connection position of the return oil line 4 is switched accordingly. Based on the control principle of the rodless chamber and the rod chamber as the return oil chamber 11, stable control of the hydraulic cylinder 1 performing reciprocating motion to drive the load 10 can be achieved.

[0042] Furthermore, regarding the operating requirements of the first type of return oil pipeline 4 and the second type of return oil pipeline 4, based on this, such as Figures 8-9 , Figures 10-11 As shown, if it is also necessary to satisfy the requirement of "high flow rate during both return and inlet oil", then at least one pressure-type variable valve 8 is required in the control valve. The speed control of the movement of the hydraulic cylinder 1 is achieved by controlling the opening degree of the variable valve core 81 of the pressure-type variable valve 8. For example, if the external pressure is increased, the opening degree of the variable valve core 81 of the pressure-type variable valve 8 increases, the flow rate of the hydraulic oil increases, and the movement speed of the hydraulic cylinder 1 increases; if the external pressure is decreased, the opening degree of the variable valve core 81 of the pressure-type variable valve 8 decreases, the flow rate of the hydraulic oil decreases, and the movement speed of the hydraulic cylinder 11 decreases. This method can achieve multi-level speed adjustment.

[0043] Example 3 like Figures 4-11 A method for controlling the movement of hydraulic cylinder 1 with high stability includes the following steps: S1: At least two control valves are connected in parallel on the return oil line of cylinder 1 under load 10. Each control valve has a different allowable flow rate. The allowable flow rate is the maximum flow rate of hydraulic oil allowed to pass through the control valve. The sum of the allowable flow rates of all control valves is equivalent to the maximum flow rate of hydraulic oil required by cylinder 1 when it is in motion. S2: When the cylinder 1 drives the load 10 to move, some or all of the control valves are opened in sequence according to the order of allowable flow from small to large. The oil return chamber in the cylinder 1 is called the oil return chamber 11, and the oil inlet chamber in the cylinder 1 is called the oil inlet chamber 12. The liquid oil in the oil return chamber 11 flows back to the oil station 2 through the oil return circuit, and the liquid oil in the oil station 2 enters the oil inlet chamber 12 through the oil inlet pipe.

[0044] The principle and beneficial effects of this control method are described in detail in Examples 1-2, and will not be described in detail here.

[0045] Example 4 Based on Example 3, the valve control system with high stability of cylinder 11 movement described in any one of the embodiments of Examples 1-2 is applied. Taking two control valves as an example, the allowable flow rate of one control valve x is 40L / min, and the allowable flow rate of the other control valve y is 160L / min. The maximum flow rate of hydraulic oil required for cylinder 11 to move is b=200L / min. If the movement of load 10 is the retraction movement of cylinder 1, then the return oil line 4 in the valve control system is connected between the rodless chamber and oil station 2 as the return oil line, and the inlet oil line 3 in the valve control system is connected between the rod chamber and oil station 2 as the inlet oil line. If the movement of load 10 is the extension movement of cylinder 1, then the return oil line 4 in the valve control system is connected between the rod chamber and oil station 2 as the return oil line, and the inlet oil line 3 in the valve control system is connected between the rodless chamber and oil station 2 as the inlet oil line. The specifics are as follows.

[0046] like Figures 4-5 , Figures 8-9 As shown, if the operating condition requirement of return oil line 4 is "high flow rate during return oil and low flow rate during inlet oil", the control method includes steps A1-A3: A1: Liquid oil in gas station 2 enters oil inlet chamber 12 through oil inlet pipe 3; A2: The hydraulic pressure in the inlet pipeline 3 acts on the pilot chamber of the pilot-operated sequence valve 9 on the return pipeline 4 through the first pilot pipeline 91, and the pilot-operated sequence valve 9 opens; the hydraulic pressure in the return pipeline 11 also flows back to the oil station 2 through the pilot-operated sequence valve 9; the pilot-operated sequence valve 9 acts as a control valve x, allowing hydraulic pressure to flow at a flow rate of 40L / min. A3: The hydraulic pressure in the inlet pipeline 3 acts on the pilot chamber of the balance valve 7 through the second pilot pipeline 73, and the sequential valve core 71 of the balance valve 7 opens; or / and the pressure-type variable valve 8 obtains external pressure from the X port, and the variable valve core 81 of the pressure-type variable valve 8 opens; the hydraulic oil in the return oil chamber 11 flows back to the oil station 2 through the sequential valve core 71 of the balance valve 7 or / and the variable valve core 81 of the pressure-type variable valve 8; the balance valve 7 or the pressure-type variable valve 8 acts as the control valve y; that is, the maximum flow rate of hydraulic oil required when returning oil in the return oil pipeline 4 reaches 40L / min + 160L / min = 200L / min.

[0047] like Figures 6-7 , Figures 10-11 As shown, if the operating condition requirement of return oil line 4 is "high flow rate during both return and inlet oil", the control method includes steps B1-B2: B1: Liquid oil in gas station 2 enters oil inlet chamber 12 through oil inlet pipe 3; B2: The hydraulic pressure in the inlet pipeline 3 acts on the pilot chamber of the balance valve 7 through the second pilot pipeline 73, and the sequential valve core 71 of the balance valve 7 opens; or / and the pressure-type variable valve 8 obtains external pressure from the X port, and the variable valve core 81 of the pressure-type variable valve 8 opens; the hydraulic oil in the return oil chamber 11 flows back to the oil station 2 through the sequential valve core 71 of the balance valve 7 or / and the variable valve core 81 of the pressure-type variable valve 8. The control valve x is the balance valve 7, and the control valve y is the balance valve 7 or the pressure-type variable valve 8. That is, the maximum flow rate of hydraulic oil required when returning oil in the return oil pipeline 4 reaches 40L / min + 160L / min = 200L / min.

[0048] It should be noted that for the two working conditions of "high flow rate during oil return and low flow rate during oil inlet" and "high flow rate during both oil return and oil inlet," the difference lies in the fact that when cylinder 1 is performing the reset motion (cylinder 1 is not moving with load 10), the pilot-operated sequence valve 9 has a flow-blocking effect on the oil inlet direction of the oil return line 4, as follows: Regarding the "high flow rate during return oil and low flow rate during inlet oil", the liquid oil in oil station 2 flows into the return oil chamber 11 through the one-way valve core 72 of the balance valve 7 on the return oil pipeline 4; or / and through the variable valve core 81 of the pressure variable valve 8; the balance valve 7 or the pressure variable valve 8 acts as the control valve y; that is, when the oil cylinder 1 performs the reset movement (the oil cylinder 1 does not move with the load 10), the maximum flow rate of the liquid oil in the return oil pipeline 4 can only reach 160L / min.

[0049] The statement "both return and inlet oil flow rates are high" is similar to "return oil flow rate is high, inlet oil flow rate is low". However, since there is no pilot-operated sequence valve 9, control valve x is a balance valve 7, control valve y is a balance valve 7 or a pressure-type variable valve 8, when the cylinder 1 performs the reset motion (the cylinder 1 does not move with the load 10), the maximum flow rate of the liquid oil in the return oil line 4 can only reach 40L / min + 160L / min = 200L / min.

[0050] Furthermore, increasing the external pressure increases the opening of the variable valve core 81 of the pressure-type variable valve 8, increasing the flow rate of the hydraulic oil and increasing the movement speed of the hydraulic cylinder 1; decreasing the external pressure decreases the opening of the variable valve core 81 of the pressure-type variable valve 8, decreasing the flow rate of the hydraulic oil and decreasing the movement speed of the hydraulic cylinder 1. For the above operating conditions, if the movement speed of the hydraulic cylinder 1 is required to be non-adjustable, i.e., the control valve y is the balance valve 7, this method can achieve two-level speed adjustment; such as Figures 8-9 , Figures 10-11 As shown, if the movement speed of the hydraulic cylinder 1 is required to be adjustable, that is, the control valve is a pressure-type variable valve 8, this method can achieve stepless speed adjustment.

[0051] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. A valve control system with high stability of cylinder movement, characterized in that: It includes a return oil line (4) and an inlet oil line (3) for connecting the oil cylinder (1) and the oil station (2); at least two control valves are connected in parallel on the return oil line (4), each control valve has a different allowable flow rate, the allowable flow rate is the maximum flow rate of liquid oil allowed to pass through the control valve; the sum of the allowable flow rates of all control valves is equivalent to the maximum flow rate of liquid oil required when the oil cylinder (1) drives the load (10) to move; The control valve is one or more of the following: pilot-operated sequence valve (9), balance valve (7), and pressure-type variable valve (8). The type and number of control valves are selected according to the working conditions of the cylinder (1). If the working condition requirement of the return oil line (4) is "large flow rate when returning oil and small flow rate when entering oil", then at least one pilot-operated sequence valve (9) is required in the control valve. The pilot chamber of the pilot-operated sequence valve (9) is connected to the oil inlet line (3) through the first pilot line (91). The other control valves are balance valves (7) and / or pressure-type variable valves (8). The pilot chamber of the balance valve (7) is connected to the oil inlet line (3) through the second pilot line (73). If the working condition requirement of the return oil line (4) is "large flow rate during both return and inlet", then the control valve is composed of a balance valve (7) and / or a pressure-type variable valve (8). The pilot chamber of the balance valve (7) is connected to the inlet oil line (3) through the second pilot line (73).

2. The valve control system according to claim 1, characterized in that: If the working condition of the return oil line (4) requires "stepless adjustment of oil flow", then at least one pressure-type variable valve (8) must be present in the control valve.

3. A control method for highly stable cylinder movement, employing the valve control system for highly stable cylinder movement as described in any one of claims 1-2, characterized in that: Includes the following steps: S1: At least two control valves are connected in parallel on the return oil line of the cylinder (1) under load (10) movement. Each control valve has a different allowable flow rate. The allowable flow rate is the maximum flow rate of the hydraulic oil allowed by the control valve. The sum of the allowable flow rates of all control valves is equivalent to the maximum flow rate of hydraulic oil required by the cylinder (1) when it is in motion. S2: When the cylinder (1) drives the load (10) to move, the control valves are opened in sequence according to the order of allowable flow from small to large. The oil return chamber in the cylinder (1) is called the oil return chamber (11), and the oil inlet chamber in the cylinder (1) is called the oil inlet chamber (12). The liquid oil in the oil return chamber (11) flows back to the oil station (2) through the oil return path, and the liquid oil in the oil station (2) enters the oil inlet chamber (12) through the oil inlet pipe.

4. The control method according to claim 3, characterized in that: If the load (10) moves as the cylinder (1) retracts, then the return oil line (4) in the valve control system is connected between the rodless chamber and the oil station (2) as the return oil line, and the inlet oil line (3) in the valve control system is connected between the rod chamber and the oil station (2) as the inlet oil line; if the load (10) moves as the cylinder (1) extends, then the return oil line (4) in the valve control system is connected between the rod chamber and the oil station (2) as the return oil line, and the inlet oil line (3) in the valve control system is connected between the rodless chamber and the oil station (2) as the inlet oil line.

5. The control method according to claim 4, characterized in that: If the operating condition requirement of the return oil pipeline (4) is "high flow rate during return oil and low flow rate during inlet oil", the control method includes steps A1-A3: A1: Liquid oil in the gas station (2) enters the oil inlet chamber (12) through the oil inlet pipe (3); A2: The hydraulic pressure in the inlet pipeline (3) acts on the pilot chamber of the pilot sequence valve (9) on the return pipeline (4) through the first pilot pipeline (91), and the pilot sequence valve (9) opens; the oil in the return chamber (11) also flows back to the oil station (2) through the pilot sequence valve (9). A3: The hydraulic pressure in the inlet pipeline (3) acts on the pilot chamber of the balance valve (7) through the second pilot pipeline (73), and the sequential valve core (71) of the balance valve (7) opens; or / and the pressure-type variable valve (8) obtains the pressure provided by the outside from the X port, and the variable valve core (81) of the pressure-type variable valve (8) opens; the hydraulic oil in the return oil chamber (11) flows back to the oil station (2) through the sequential valve core (71) of the balance valve (7) or / and the variable valve core (81) of the pressure-type variable valve (8); If the operating condition requirement of the return oil pipeline (4) is "high flow rate during both return and inlet", the control method includes steps B1-B2: B1: Liquid oil in the gas station (2) enters the oil inlet chamber (12) through the oil inlet pipe (3); B2: The hydraulic pressure in the inlet pipeline (3) acts on the pilot chamber of the balance valve (7) through the second pilot pipeline (73), and the sequential valve core (71) of the balance valve (7) opens; or / and the pressure-type variable valve (8) obtains the pressure provided by the outside from the X port, and the variable valve core (81) of the pressure-type variable valve (8) opens; the hydraulic oil in the return oil chamber (11) flows back to the oil station (2) through the sequential valve core (71) of the balance valve (7) or / and the variable valve core (81) of the pressure-type variable valve (8).

6. The control method according to claim 5, characterized in that: Increasing the external pressure increases the opening of the variable valve core (81) of the pressure-type variable valve (8), increases the flow rate of the hydraulic oil, and increases the movement speed of the cylinder (1); decreasing the external pressure decreases the opening of the variable valve core (81) of the pressure-type variable valve (8), decreases the flow rate of the hydraulic oil, and decreases the movement speed of the cylinder (1).

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