Variable amplitude balance valve and hydraulic system

Abstract

The utility model belongs to the field of balance valves, and particularly relates to a variable-amplitude balance valve and a hydraulic system.The variable-amplitude balance valve introduces oil return back pressure into a spring cavity of the balance valve through a hydraulic half-bridge formed by damping by means of the characteristic that when gravity variable-amplitude lowering is conducted, the pressure of the spring cavity is increased, and the pressure loss of an oil return pipeline is larger when flow is too large; the pressure of the pilot port is overcome to push the valve core to reset, and the opening degree of the balance valve is reduced, so that the oil return flow is reduced and the variable-amplitude lowering speed is slowed down. Meanwhile, the pressure is rapidly reduced when the rod cavity of the variable-amplitude oil cylinder is rapidly lowered, the pressure loss is increased after the oil return flow of the rodless cavity is increased, and the automatic oil supplementing effect is achieved through the pressure difference between the pressure loss and the rodless cavity.

Description

Technical Field

[0001] This application relates to the technical field of balance valves, and particularly to a luffing balance valve and a hydraulic system. Background Art

[0002] A balance valve is a valve that allows fluid to flow unidirectionally. To open it in the reverse direction, it must be controlled by a pilot pressure. The opening size of the valve is proportional to the pilot pressure.

[0003] Engineering construction machinery has increasingly higher requirements for operation efficiency and energy efficiency. During gravity luffing descent, the weight of the oil cylinder, the working platform, and the load are utilized, and the gravity potential energy is used to retract the luffing oil cylinder, achieving the descent action of the luffing mechanism, achieving the purpose of energy regeneration, improving the execution speed, and enabling precise motion control at the same time.

[0004] Gravity luffing descent is widely used in engineering construction machinery such as aerial work platforms, cranes, and telescopic forklifts. During luffing gravity descent, the gravity potential energy is converted into kinetic energy. If the opening of the balance valve or the hydraulic control pilot port is not adjusted, the luffing descent action speed will become faster and faster, resulting in jitter and speed mutation phenomena. At the same time, the rodless cavity of the oil cylinder discharges oil rapidly. If the rodless cavity is not effectively refilled with oil, the rod chamber will form a suction void state, seriously affecting the stability and safety of the equipment. Summary of the Utility Model

[0005] The embodiments of this application provide a luffing balance valve and a hydraulic system, which are used to solve the problems of boom jitter, speed mutation, and the formation of a suction void state in the rod chamber during luffing gravity descent.

[0006] To this end, according to one aspect of this application, a luffing balance valve is provided, which includes a first oil port, a second oil port, a third oil port, a fourth oil port, an oil return port, a pilot oil port, a balance valve, a first check valve, a second check valve, a third check valve, a first damping orifice, and a second damping orifice;

[0007] The first oil port is connected to the second oil port, and the second oil port is used to connect to the rod chamber of the luffing cylinder; the third oil port, the first one-way valve, the balance valve, and the fourth oil port are connected in series in sequence. The fourth oil port is used to connect to the rodless chamber of the luffing cylinder. The first one-way valve opens when the oil flows from the balance valve to the third oil port; the pilot oil port is connected to the pilot port of the balance valve; the oil return port is connected to the spring chamber of the balance valve; the inlet of the second one-way valve is connected to the oil circuit between the first one-way valve and the balance valve, and the outlet of the second one-way valve is connected to the oil circuit between the first oil port and the second oil port; the inlet of the third one-way valve is connected to the third oil port, and the outlet of the third one-way valve is connected to the fourth oil port; the second damping hole is arranged on the oil circuit between the oil return port and the spring chamber of the balance valve. One end of the first damping hole is connected to the oil circuit between the first one-way valve and the balance valve, and the other end is connected to the oil circuit between the second damping hole and the spring chamber of the balance valve.

[0008] Optionally, the luffing balance valve further includes a third damping hole, and the third damping hole is arranged on the oil circuit between the pilot oil port and the pilot port of the balance valve.

[0009] Optionally, the aperture of the third damping hole is 0.6 mm - 0.9 mm.

[0010] Optionally, the pilot ratio of the balance valve is 1:0, and the set pressure is 7.5 Bar.

[0011] Optionally, the aperture of the first damping hole is 0.3 mm - 0.6 mm.

[0012] Optionally, the aperture of the second damping hole is 0.6 mm - 0.9 mm.

[0013] According to another aspect of the present application, a hydraulic system is provided, including a luffing cylinder and the luffing balance valve as described above. The rod chamber of the luffing cylinder is connected to the second oil port, and the rodless chamber of the luffing cylinder is connected to the fourth oil port.

[0014] The beneficial effects of the luffing balance valve and the hydraulic system provided by the present application are as follows: Compared with the prior art, when the luffing balance valve of the present application uses gravity to luff down, when the flow rate is too large, the pressure loss of the oil return pipeline is greater. The oil return back pressure is introduced into the spring chamber of the balance valve through the hydraulic half-bridge formed by the damping, making the pressure in the spring chamber higher, overcoming the pressure at the pilot port to push the spool to reset, reducing the opening of the balance valve, thereby reducing the oil return flow rate and slowing down the luffing down speed. At the same time, when the rod chamber of the luffing cylinder quickly descends, the pressure rapidly decreases, and when the oil return flow rate of the rodless chamber increases, the pressure loss increases. The differential pressure between the two is used to form an automatic oil replenishment effect. Description of the Drawings

[0015] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0016] Wherein:

[0017] Figure 1 is a schematic diagram showing the working principle of the boom balance valve shown in an embodiment of the present application.

[0018] Main element symbol description:

[0019] 10. Boom balance valve;

[0020] 101. First oil port; 102. Second oil port; 103. Third oil port; 104. Fourth oil port; 105. Oil return port; 106. Pilot oil port;

[0021] 11. Balance valve; 12. First check valve; 13. Second check valve; 14. Third check valve; 15. First damping hole; 16. Second damping hole; 17. Third damping hole;

[0022] 20. Boom cylinder;

[0023] 21. Rod chamber; 22. Rodless chamber. Detailed implementation manners

[0024] To facilitate the understanding of the present application, the following will describe the present application more comprehensively with reference to the relevant accompanying drawings. The preferred embodiments of the present application are shown in the accompanying drawings. However, the present application can be implemented in many other different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure content of the present application more thorough and comprehensive.

[0025] It should be noted that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0026] It should be understood that the orientation or positional relationship indicated by terms such as "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0027] In addition, descriptions such as "first", "second", etc. are only for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the description of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0029] According to one aspect of the present application, embodiments of the present application provide a boom balance valve, as Figure 1 shown. The boom balance valve 10 includes a first oil port 101, a second oil port 102, a third oil port 103, a fourth oil port 104, an oil return port 105, a pilot oil port 106, a balance valve 11, a first check valve 12, a second check valve 13, a third check valve 14, a first damping hole 15, and a second damping hole 16. The first oil port 101 is connected to the second oil port 102, and the second oil port 102 is used to connect to the rod chamber 21 of the boom cylinder 20; the third oil port 103, the first check valve 12, the balance valve 11, and the fourth oil port 104 are connected in series in sequence. The fourth oil port 104 is used to connect to the rodless chamber 22 of the boom cylinder 20, and the first check valve 12 opens when the oil flows from the balance valve 11 to the third oil port 103; the pilot oil port 106 is connected to the pilot port of the balance valve 11; the oil return port 105 is connected to the spring chamber of the balance valve 11; the inlet of the second check valve 13 is connected to the oil path between the first check valve 12 and the balance valve 11, and the outlet of the second check valve 13 is connected to the oil path between the first oil port 101 and the second oil port 102; the inlet of the third check valve 14 is connected to the third oil port 103, and the outlet of the third check valve 14 is connected to the fourth oil port 104; the second damping hole 16 is provided on the oil path between the oil return port 105 and the spring chamber of the balance valve 11. One end of the first damping hole 15 is connected to the oil path between the first check valve 12 and the balance valve 11, and the other end is connected to the oil path between the second damping hole 16 and the spring chamber of the balance valve 11.

[0030] Now in combination with Figure 1, the working principle of the luffing balance valve 10 is described as follows:

[0031] Normal telescopic boom hoisting process: The pressure oil of the hydraulic system enters through the third oil port 103, directly opens the third one-way valve 14, and enters the rodless cavity 22 of the luffing cylinder 20 through the fourth oil port 104. The oil in the rod cavity 21 of the luffing cylinder 20 enters the second oil port 102 and then returns to the fuel tank through the first oil port 101. At this time, the piston rod of the luffing cylinder 20 extends and the telescopic boom hoists.

[0032] Normal telescopic boom lowering process: The control pressure oil enters the pilot oil port 106 and acts on the pilot port of the balance valve 11 to open the balance valve 11. At this time, due to the self-weight of the luffing cylinder 20, the piston rod of the luffing cylinder 20 retracts, and the oil in the rodless cavity 22 returns oil through the fourth oil port 104 at the opened balance valve 11, passes through the second one-way valve 13, reaches the third oil port 103, and returns to the fuel tank. At this time:

[0033] When the load in the rodless cavity 22 of the luffing cylinder 20 is too high (such as in the case of heavy load or falling faster and faster), when the balance valve 11 has the same opening, due to the increased pressure difference across the balance valve 11, the flow rate through the balance valve 11 increases. The back pressure of the oil returning from the third oil port 103 increases significantly. At this time, the oil pressure between the second one-way valve 13 and the balance valve 11 enters the spring chamber through the first damping hole 15, and then enters the oil return port 105 through the second damping hole 16. At this time, the first damping hole 15 and the second damping hole 16 form a hydraulic half-bridge. At this time, the back pressure acting on P2 is: P2 = (P1 - P3) * correction factor, where the correction factor depends on the ratio of the damping of the hydraulic half-bridge. According to the measured experience, the correction factor should be less than 0.2. The pressure P2 acts on the spring chamber of the balance valve 11, and the spool of the balance valve 11 tends to reset, the opening of the balance valve 11 decreases, and when the pressure difference across the balance valve 11 remains unchanged, the flow rate through the balance valve 11 decreases;

[0034] When the load in the rodless cavity 22 of the luffing cylinder 20 is too high (such as in the case of heavy load or falling faster and faster), when the balance valve 11 has the same opening, due to the increased pressure difference across the balance valve 11, the flow rate through the balance valve 11 increases. The back pressure of the oil returning from the third oil port 103 increases significantly, while the pressure in the rod cavity 21 of the luffing cylinder 20 rapidly decreases due to the need for oil replenishment. At this time, a pressure difference is formed between P1 and P4, so that the flow rate originally in the rodless cavity 22 of the luffing cylinder 20 is replenished into the rod cavity 21 of the luffing cylinder 20 through the second one-way valve 13, forming flow regeneration and saving energy consumption.

[0035] In an embodiment of the present application, when the luffing balance valve 10 utilizes gravity to lower the boom, due to the characteristic that the pressure loss of the oil return pipeline is greater when the flow rate is too large, the oil return backpressure is introduced into the spring chamber of the balance valve 11 through a hydraulic half-bridge formed by damping, increasing the pressure in the spring chamber, overcoming the pressure at the pilot port to push the spool back to its original position, reducing the opening degree of the balance valve 11, thereby reducing the oil return flow rate and slowing down the speed of the boom lowering. At the same time, when the rod chamber 21 of the luffing cylinder 20 rapidly lowers, the pressure rapidly decreases, and when the oil return flow rate of the rodless chamber 22 increases, the pressure loss increases, and an automatic oil replenishment effect is formed by utilizing the pressure difference between the two.

[0036] In one embodiment, as Figure 1 shown, the luffing balance valve 10 further includes a third damping orifice 17, and the third damping orifice 17 is provided on the oil path between the pilot oil port 106 and the pilot port of the balance valve 11.

[0037] The third damping orifice 17 plays a role in filtering and stabilizing the pressure signal acting at the pilot port, thereby ensuring the stable operation of the hydraulic system.

[0038] Since the volume of the control chamber of the balance valve 11 is very small and the flow rate in and out of the control chamber is very small, the aperture of the third damping orifice 17 must be very small to function. If the aperture is too small, it is easily blocked by contaminated particles, so the aperture is generally 0.6 mm - 0.9 mm.

[0039] Preferably, the aperture of the third damping orifice 17 is 0.8 mm.

[0040] It should be noted that the third damping orifice 17 can also adopt adjustable damping, and the aperture size is determined through experiments.

[0041] In one embodiment, as Figure 1 shown, the pilot ratio of the balance valve 11 is 1:0, and the set pressure is 7.5 Bar.

[0042] In one embodiment, as Figure 1 shown, the aperture of the first damping orifice 15 is 0.3 mm - 0.6 mm, preferably 0.5 mm, and the aperture of the second damping orifice 16 is 0.6 mm - 0.9 mm, preferably 0.8 mm. It can be understood that the first damping orifice 15 and the second damping orifice 16 can also adopt adjustable damping.

[0043] According to another aspect of the present application, an embodiment of the present application further provides a hydraulic system, including a luffing cylinder 20 and the luffing balance valve 10 in any of the above embodiments. The rod chamber 21 of the luffing cylinder 20 is connected to the second oil port 102, and the rodless chamber 22 of the luffing cylinder 20 is connected to the fourth oil port 104.

[0044] Since the luffing balance valve 10 in the above embodiment is adopted, the hydraulic system also has the advantages and benefits brought by the above luffing balance valve 10 and is more stable and safe during operation.

[0045] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0046] The above embodiments only represent several implementation manners of the present application, and the description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A variable amplitude balancing valve, characterized in that: It includes a first oil port, a second oil port, a third oil port, a fourth oil port, an oil return port, a pilot oil port, a balance valve, a first check valve, a second check valve, a third check valve, a first damping hole and a second damping hole; The first oil port is connected to the second oil port, and the second oil port is used to connect the rod chamber of the variable-length oil cylinder; the third oil port, the first one-way valve, the balancing valve and the fourth oil port are connected in series in sequence, and the fourth oil port is used to connect the rodless chamber of the variable-length oil cylinder, and the first one-way valve is opened when the oil flows from the balancing valve to the third oil port; the pilot oil port is connected to the pilot port of the balancing valve; the oil return port is connected to the spring chamber of the balancing valve; the inlet of the second one-way valve is connected to the oil circuit between the first one-way valve and the balancing valve, and the outlet of the second one-way valve is connected to the oil circuit between the first oil port and the second oil port; the inlet of the third one-way valve is connected to the third oil port, and the outlet of the third one-way valve is connected to the fourth oil port; the second damping hole is arranged on the oil circuit between the oil return port and the spring chamber of the balancing valve, one end of the first damping hole is connected to the oil circuit between the first one-way valve and the balancing valve, and the other end is connected to the oil circuit between the second damping hole and the spring chamber of the balancing valve.

2. The variable amplitude balancing valve according to claim 1, characterized in that: The variable amplitude balancing valve further includes a third damping hole, and the third damping hole is arranged in the oil path between the pilot oil port and the pilot port of the balancing valve.

3. The variable amplitude balancing valve according to claim 2, characterized in that: The aperture of the third damping hole is 0.6 mm-0.9 mm.

4. The variable amplitude balancing valve according to claim 1, characterized in that: The pilot ratio of the balancing valve is 1:0 and the set pressure is 7.5 Bar.

5. The variable amplitude balancing valve according to claim 1, characterized in that: The aperture of the first damping hole is 0.3 mm-0.6 mm.

6. The variable amplitude balancing valve according to claim 1, characterized in that: The aperture of the second damping hole is 0.6 mm-0.9 mm.

7. A hydraulic system, characterized in that: It comprises a luffing oil cylinder and a luffing balancing valve as described in any one of claims 1 to 6, wherein the rod chamber of the luffing oil cylinder is connected to the second oil port, and the rodless chamber of the luffing oil cylinder is connected to the fourth oil port.

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