Hydraulic control system and forklift

Abstract

The utility model relates to the technical field of hydraulic control, and discloses a hydraulic control system and a forklift. The hydraulic control system comprises a hydraulic oil cylinder, an oil inlet pipeline, a first electromagnetic valve, an oil return pipeline, a compensation type proportional flow valve and a second electromagnetic valve, one end of the oil inlet pipeline is constructed to be a first oil inlet, and the other end of the oil inlet pipeline communicates with the hydraulic oil cylinder; the first electromagnetic valve is arranged on the oil inlet pipeline and located between the first oil inlet and the hydraulic oil cylinder. The oil return pipeline is provided with a first end and a second end, the first end of the oil return pipeline is communicated with the oil inlet pipeline and located between the first electromagnetic valve and the hydraulic oil cylinder, the compensation type proportional flow valve and the second electromagnetic valve are both arranged on the oil return pipeline, and the compensation type proportional flow valve is located between the second electromagnetic valve and the first oil return opening. And the second electromagnetic valve selectively blocks the oil return pipeline. The compensation valve solves the technical problem that in the load maintaining process of a forklift, hydraulic oil can leak from the compensation valve, and then the load maintaining reliability of the forklift is poor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydraulic control, and particularly relates to a hydraulic control system and a forklift. BACKGROUND

[0002] With the maturity and development of the hydraulic control system, as a key mode of power transmission, the importance of the hydraulic system is increasingly highlighted.

[0003] In the related art, the control of the lifting and lowering of the forks of the forklift is mainly achieved by controlling the hydraulic oil in the oil cylinder to generate hydraulic pressure, so as to stably lift or lower the goods. However, in the process of maintaining the load of the forklift, the hydraulic oil leaks from the compensation valve, thereby causing poor reliability of the forklift in maintaining the load. CONTENT OF THE UTILITY MODEL

[0004] The present application provides a hydraulic control system and a forklift, which solve the technical problem that in the process of maintaining the load of the forklift, the hydraulic oil leaks from the compensation valve, thereby causing poor reliability of the forklift in maintaining the load.

[0005] In order to achieve the above-mentioned purpose, the main technical scheme adopted by the present application comprises:

[0006] In a first aspect, the present application provides a hydraulic control system, which comprises a hydraulic oil cylinder, an oil inlet pipeline, a first electromagnetic valve, an oil return pipeline, a compensation type proportional flow valve and a second electromagnetic valve. One end of the oil inlet pipeline is configured as a first oil inlet port, and the other end of the oil inlet pipeline is in communication with the hydraulic oil cylinder. The first electromagnetic valve is arranged on the oil inlet pipeline and located between the first oil inlet port and the hydraulic oil cylinder. The oil return pipeline has a first end and a second end. The first end of the oil return pipeline is in communication with the hydraulic oil cylinder, or the first end of the oil return pipeline is in communication with the oil inlet pipeline and located between the first electromagnetic valve and the hydraulic oil cylinder. The second end of the oil return pipeline is configured as a first oil return port. The compensation type proportional flow valve and the second electromagnetic valve are both arranged on the oil return pipeline. The compensation type proportional flow valve is located between the second electromagnetic valve and the first oil return port. The second electromagnetic valve can selectively block the oil return pipeline.

[0007] The hydraulic control system provided by the present application has the compensation type proportional flow valve located between the second electromagnetic valve and the first oil return port, and the second electromagnetic valve can selectively block the oil return pipeline. In this way, when the hydraulic control system needs to maintain the load, the hydraulic oil cannot flow to the compensation type proportional flow valve, thereby avoiding the leakage and discharge of oil at the compensation type proportional flow valve, and improving the stability and reliability of the operation of the hydraulic control system.

[0008] Optionally, the first electromagnetic valve is configured as a double-stop electromagnetic valve or a proportional valve.

[0009] The first electromagnetic valve is configured as a double cut-off electromagnetic valve, and hydraulic oil cannot leak from the hydraulic oil cylinder to the first oil inlet, so that the phenomenon of oil backflow caused by pressure fluctuation of the hydraulic control system or other reasons can be prevented, and the first electromagnetic valve is configured as a proportional valve, so that the first electromagnetic valve can continuously and proportionally adjust the oil flow in the oil inlet pipeline according to the input electric signal, so that the movement speed of the hydraulic oil in the hydraulic oil cylinder can be more accurately controlled.

[0010] Optionally, the hydraulic control system further comprises a one-way valve, and the one-way valve is arranged between the first electromagnetic valve and the first oil inlet.

[0011] The one-way valve can prevent the hydraulic oil from flowing backward, and the one-way valve arranged between the first electromagnetic valve and the first oil inlet can ensure that the hydraulic oil can only flow from the first oil inlet to the first electromagnetic valve and the hydraulic oil cylinder, so as to avoid damage to the parts of the hydraulic control system caused by the backflow of the oil.

[0012] Optionally, the hydraulic control system comprises a filter screen, and the filter screen is arranged in the oil return pipeline and located between the second electromagnetic valve and the first end.

[0013] The filter screen is arranged in the oil return pipeline and located between the second electromagnetic valve and the first end, so that the probability of damage to the compensation type proportional flow valve and the second electromagnetic valve can be reduced, and the stability and reliability of the operation of the hydraulic control system can be improved.

[0014] Optionally, the compensation type proportional flow valve is configured as a two-way compensation type proportional flow valve or a three-way compensation type proportional flow valve.

[0015] The compensation type proportional flow valve is configured as a two-way compensation type proportional flow valve or a three-way compensation type proportional flow valve, and the compensation type proportional flow valve can adjust the flow rate of the hydraulic oil flowing through the compensation type proportional flow valve, so as to adjust the movement speed of the goods.

[0016] Optionally, the compensation type proportional flow valve comprises a proportional adjusting part and a pressure compensation part, the proportional adjusting part is arranged between the pressure compensation part and the second electromagnetic valve, and the compensation type proportional flow valve further comprises a compensation oil path, one end of the compensation oil path is in communication with an inlet of the proportional adjusting part, and the other end of the compensation oil path is in communication with an outlet of the proportional adjusting part.

[0017] One end of the compensation oil path is in communication with the inlet of the proportional adjusting part, and the other end of the compensation oil path is in communication with the outlet of the pressure proportional adjusting part, when the hydraulic control system appears pressure fluctuation, the pressure compensation part can quickly respond, adjust the valve opening to balance the pressure change, avoid the flow mutation caused by pressure fluctuation, reduce the vibration and impact of the hydraulic control system, and make the hydraulic control system run more smoothly.

[0018] In a second aspect, the embodiments of the present application provide a hydraulic control system, which comprises a hydraulic cylinder, an oil inlet pipeline, a first electromagnetic valve, an oil return pipeline, a proportional adjusting valve, a pressure compensation valve and a second electromagnetic valve. One end of the oil inlet pipeline is configured as a first oil inlet port, and the other end of the oil inlet pipeline is in communication with the hydraulic cylinder. The first electromagnetic valve is arranged on the oil inlet pipeline and located between the first oil inlet port and the hydraulic cylinder. The oil return pipeline has a first end and a second end. The first end of the oil return pipeline is in communication with the hydraulic cylinder, or the first end of the oil return pipeline is in communication with the oil inlet pipeline and located between the first electromagnetic valve and the hydraulic cylinder. The second end of the oil return pipeline is configured as a first oil return port. The proportional adjusting valve and the pressure compensation valve are both arranged on the oil return pipeline. The pressure compensation valve is arranged between the proportional adjusting valve and the first oil return port. The inlet of the proportional adjusting valve is connected to the outlet of the proportional adjusting valve through a compensation oil circuit. The second electromagnetic valve is arranged on the compensation oil circuit or the oil return pipeline and located between the proportional adjusting valve and the first end.

[0019] The second electromagnetic valve is arranged on the compensation oil circuit or the oil return pipeline and located between the proportional adjusting valve and the first end. When the hydraulic control system maintains the load of the goods, the second electromagnetic valve can disconnect the communication between the pressure compensation valve and the hydraulic cylinder. The hydraulic oil in the hydraulic cylinder cannot flow to the pressure compensation valve, and the hydraulic oil cannot leak or leak out from the pressure compensation valve. In this way, the stability and reliability of the operation of the hydraulic control system can be improved.

[0020] Optionally, the first electromagnetic valve is configured as a double-stop electromagnetic valve or a proportional valve.

[0021] The first electromagnetic valve is configured as a double-stop electromagnetic valve. The hydraulic oil cannot leak from the hydraulic cylinder to the first oil inlet port. In this way, the occurrence of the phenomenon of reverse flow of oil due to pressure fluctuation of the hydraulic control system or other reasons can be prevented. The first electromagnetic valve is configured as a proportional valve. The first electromagnetic valve can continuously and proportionally adjust the flow of oil in the oil inlet pipeline according to the input electrical signal. This makes the movement speed of the hydraulic oil in the hydraulic cylinder more accurately controllable.

[0022] Optionally, the hydraulic control system comprises a filter screen, which is arranged on the oil return pipeline and located between the proportional adjusting valve and the first end.

[0023] The filter screen is arranged on the oil return pipeline and located between the proportional adjusting valve and the first end. In this way, the probability of damage to the proportional adjusting valve and the pressure compensation valve can be reduced, and the stability and reliability of the operation of the hydraulic control system can be improved.

[0024] In a third aspect, the embodiments of the present application provide a forklift, which comprises the hydraulic control system of any one of the embodiments of the present application.

[0025] The forklift provided by the embodiment of the application can avoid the probability of oil leakage at the pressure compensation part or pressure compensation valve of the hydraulic control system when the forklift holds a load, and improve the stability and reliability of the forklift operation. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the specific embodiments or prior art of the present application, the drawings needed in the specific embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0027] Figure 1 The structural schematic diagram of the hydraulic control system provided by an embodiment of the present application is shown in the figure.

[0028] Figure 2 The structural schematic diagram of the hydraulic control system provided by an embodiment of the present application is shown in the figure.

[0029] Figure 3 The structural schematic diagram of the hydraulic control system provided by an embodiment of the present application is shown in the figure.

[0030] Figure 4 The structural schematic diagram of the hydraulic control system provided by an embodiment of the present application is shown in the figure.

[0031] Figure 5 The structural schematic diagram of the forklift provided by an embodiment of the present application is shown in the figure.

[0032]

Explanation of reference numerals

[0033] Forklift 1000

[0034] Hydraulic control system 100

[0035] Hydraulic oil cylinder 110

[0036] Oil inlet pipeline 120; first oil inlet 121

[0037] First electromagnetic valve 130

[0038] Oil return pipeline 140; first end 141; second end 142; first oil return port 143

[0039] Compensated proportional flow valve 150; proportional adjusting part 151; pressure compensation part 152

[0040] Second electromagnetic valve 160

[0041] One-way valve 170

[0042] filter screen 180;

[0043] compensation oil passage 190;

[0044] proportional control valve 200;

[0045] pressure compensation valve 210. DETAILED DESCRIPTION

[0046] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0047] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs; the terms used in the specification of the present application are only for the purpose of describing the specific embodiments and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion. The terms "first", "second" and the like in the specification and claims of the present application and the above description of drawings are used to distinguish different objects, and are not intended to describe a particular order or primary and secondary relationship.

[0048] In the present application, the phrase "embodiment" means that the specific features, structures or characteristics described in connection with the embodiment can be included in at least one embodiment of the present application. The phrase appears in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment to other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in the present application can be combined with other embodiments.

[0049] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mount", "connect", "connection", "attach" should be understood broadly, for example, can be fixedly connected, can be detachably connected, or integrally connected; can be directly connected, or indirectly connected through an intermediate medium; can be internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0050] The term "and / or", in this application, is only to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in this application generally represents an "or" relationship between the front and rear associated objects.

[0051] "Multiple" appearing in this application refers to more than two (including two), and similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0052] In the process of modern industrial automation, hydraulic control systems have become the core technology support in the field of power transmission due to their high precision, high power density, and fast response characteristics. From engineering machinery to aerospace, from metallurgical equipment to marine vessels, hydraulic transmission systems have continuously driven the iterative upgrading of equipment technology in various industries with their stable and reliable energy conversion efficiency.

[0053] In the field of logistics and warehousing, forklifts are indispensable handling equipment, and the hydraulic control system of their fork lifting mechanism is a core component. Under the current technical system, forklifts adjust the flow and pressure of hydraulic oil in the hydraulic cylinder to achieve smooth lifting and precise landing of goods. Specifically, the hydraulic pump converts mechanical energy into hydraulic energy to drive the hydraulic oil to flow in a closed circuit. After accurate control by the control valve group, the hydraulic oil enters the cylinder to act on the piston, and the piston rod is driven to extend or retract by hydraulic pressure, thereby completing the dynamic adjustment of the fork height. This system can achieve fine operation of different weight goods through the synergistic effect of pressure feedback and flow control.

[0054] However, when the fork carrying goods is in a stationary state, due to the limitations of the compensation valve sealing structure, such as a spool valve structure, the hydraulic oil will seep out in small amounts under long-term pressure. Small leakage, under long-time operation or heavy load conditions, can cause the fork to sink and displace.

[0055] In view of this, the embodiment of the present application provides a hydraulic control system and a forklift, the hydraulic control system comprising a hydraulic cylinder, an oil inlet pipeline, a first electromagnetic valve, an oil return pipeline, a compensation type proportional flow valve and a second electromagnetic valve, one end of the oil inlet pipeline is configured as a first oil inlet, the other end of the oil inlet pipeline is in communication with the hydraulic cylinder; the first electromagnetic valve is arranged on the oil inlet pipeline and located between the first oil inlet and the hydraulic cylinder; the oil return pipeline has a first end and a second end, the first end of the oil return pipeline is in communication with the hydraulic cylinder, or the first end of the oil return pipeline is in communication with the oil inlet pipeline and located between the first electromagnetic valve and the hydraulic cylinder, and the second end of the oil return pipeline is configured as a first oil return port; the compensation type proportional flow valve and the second electromagnetic valve are both arranged on the oil return pipeline, the compensation type proportional flow valve is located between the second electromagnetic valve and the first oil return port, and the second electromagnetic valve can selectively block the oil return pipeline.

[0056] In the above scheme, the compensation type proportional flow valve is located between the second electromagnetic valve and the first oil return port, and the second electromagnetic valve can selectively block the oil return pipeline, so that when the hydraulic control system needs to maintain the load, the hydraulic oil cannot flow to the compensation type proportional flow valve, the phenomenon of oil leakage and oil leakage at the compensation type proportional flow valve is avoided, and the stability and reliability of the operation of the hydraulic control system are improved.

[0057] The following embodiments are described with the hydraulic control system of an embodiment of the present application for the convenience of description.

[0058] Figure 1 The structural schematic diagram of the hydraulic control system provided by an embodiment of the present application is shown in the figure; Figure 2 The structural schematic diagram of the hydraulic control system provided by an embodiment of the present application is shown in the figure; Figure 3 When the compensation type proportional flow valve provided by the embodiment of the present application is configured as a three-way compensation type proportional flow valve, the structural schematic diagram of the hydraulic control system is shown in the figure; Figure 4 The structural schematic diagram of the hydraulic control system provided by an embodiment of the present application is shown in the figure; Figure 5 The structural schematic diagram of the forklift provided by the embodiment of the present application is shown in the figure.

[0059] Please refer to Figure 1In the embodiment, the hydraulic control system 100 comprises a hydraulic cylinder 110, an oil inlet pipeline 120, a first electromagnetic valve 130, an oil return pipeline 140, a compensation type proportional flow valve 150 and a second electromagnetic valve 160. One end of the oil inlet pipeline 120 is configured as a first oil inlet port 121, and the other end of the oil inlet pipeline 120 is communicated with the hydraulic cylinder 110. The first electromagnetic valve 130 is arranged in the oil inlet pipeline 120 and between the first oil inlet port 121 and the hydraulic cylinder 110. The oil return pipeline 140 has a first end 141 and a second end 142. The first end 141 of the oil return pipeline 140 is communicated with the hydraulic cylinder 110 or the first end 141 of the oil return pipeline 140 is communicated with the oil inlet pipeline 120 and between the first electromagnetic valve 130 and the hydraulic cylinder 110, and the second end 142 of the oil return pipeline 140 is configured as a first oil return port 143. The compensation type proportional flow valve 150 and the second electromagnetic valve 160 are arranged in the oil return pipeline 140. The compensation type proportional flow valve 150 is between the second electromagnetic valve 160 and the first oil return port 143, and the second electromagnetic valve 160 can selectively block the oil return pipeline 140.

[0060] The hydraulic cylinder 110 is used to store hydraulic oil. By controlling the content of the hydraulic oil in the hydraulic cylinder 110, the goods can be lifted. When the content of the hydraulic oil is unchanged, the goods can be kept in load, that is, kept in horizontal lifting. One end of the oil inlet pipeline 120 is configured as the first oil inlet port 121, and the other end of the oil inlet pipeline 120 is communicated with the hydraulic cylinder 110. The hydraulic oil can enter the oil inlet pipeline 120 from the first oil inlet port 121 and then flow into the hydraulic cylinder 110 from the oil inlet pipeline 120.

[0061] The first electromagnetic valve 130 is arranged between the first oil inlet port 121 and the hydraulic cylinder 110. For example, the first electromagnetic valve 130 can control the on-off of the oil passage of the oil inlet pipeline 120. When the goods are kept in load, the content of the hydraulic oil in the hydraulic cylinder 110 should be kept unchanged. The first electromagnetic valve 130 controls the oil inlet pipeline 120 to be closed. The hydraulic oil cannot flow from the hydraulic cylinder 110 into the oil inlet pipeline 120, and the hydraulic oil cannot flow from the oil inlet pipeline 120 into the hydraulic cylinder 110. The oil return pipeline 140 has a first end 141 and a second end 142. The first end 141 is communicated with the oil inlet pipeline 120 and is between the hydraulic cylinder 110 and the first electromagnetic valve 130. The hydraulic oil in the hydraulic cylinder 110 can flow from the hydraulic cylinder 110 to the first end 141. The second end 142 of the oil return pipeline 140 is configured as the first oil return port 143, and then the hydraulic oil flows out of the oil return pipeline 140 from the first oil return port 143.

[0062] The compensation type proportional flow valve 150 and the second electromagnetic valve 160 are arranged on the oil return pipeline 140. The compensation type proportional flow valve 150 has a flow adjusting function and a pressure compensation function. The compensation type proportional flow valve 150 integrates the functions of a proportional valve and a compensation valve. The compensation type proportional flow valve 150 can accurately adjust the flow of the oil return pipeline 140, flexibly adjust the oil return flow according to the actual working requirement, and accurately control the oil content in the hydraulic cylinder 110. In this way, the working accuracy and stability of some high-precision equipment, such as precision machining machine tools and automatic assembly production lines, can be effectively ensured. When the system pressure changes, the compensation type proportional flow valve 150 can automatically adjust the pressure at both ends of the compensation type proportional flow valve 150, improve the anti-interference ability and working performance of the hydraulic control system 100, and be suitable for various complex working environments.

[0063] The compensation type proportional flow valve 150 is arranged between the second electromagnetic valve 160 and the first oil return port 143, that is, the second electromagnetic valve 160 is closer to the first end 141 than the compensation type proportional flow valve 150. The second electromagnetic valve 160 can control the on-off of the oil return pipeline 140. When the second electromagnetic valve 160 controls the oil return pipeline 140 to be disconnected, the hydraulic oil flows from the hydraulic cylinder 110 to the second electromagnetic valve 160 and is cut off. The hydraulic oil cannot flow to the compensation type proportional flow valve 150. In this way, when the hydraulic control system 100 needs to maintain the load, the hydraulic oil cannot flow to the compensation type proportional flow valve 150, so as to avoid oil leakage and oil leakage at the compensation type proportional flow valve 150, and improve the stability and reliability of the hydraulic control system 100.

[0064] For example, the hydraulic control system 100 can be applied to a forklift 1000 to lift goods. When the forklift 1000 needs to lift the goods, the first electromagnetic valve 130 is opened, the hydraulic oil enters the oil inlet pipeline 120 from the first oil inlet port 121, and then flows into the hydraulic cylinder 110 from the oil inlet pipeline 120. When the forklift 1000 needs to horizontally lift the goods, the first electromagnetic valve 130 and the second electromagnetic valve 160 are both closed, the hydraulic oil cannot leak from the hydraulic cylinder 110, and the hydraulic oil cannot flow to the compensation type proportional flow valve 150. When the forklift 1000 needs to put down the goods, the hydraulic oil needs to flow out of the hydraulic cylinder 110. The first electromagnetic valve 130 is closed, the second electromagnetic valve 160 is opened, the hydraulic oil flows from the oil return pipeline 140 to the first oil return port 143, and the compensation type proportional flow valve 150 can control the flow of the hydraulic oil in the oil return pipeline 140, thereby controlling the descending speed of the goods.

[0065] In some embodiments, the first end 141 of the oil return pipeline 140 is directly communicated with the hydraulic cylinder 110, that is, the hydraulic oil can directly flow from the hydraulic cylinder 110 to the first end 141 of the oil return pipeline 140 without passing through the oil inlet pipeline 120.

[0066] Please refer to Figure 1 In this embodiment, the first electromagnetic valve 130 is configured as a double block electromagnetic valve or a proportional valve.

[0067] When the first electromagnetic valve 130 is configured as a double block electromagnetic valve, it can provide a more reliable oil path cut-off function for the hydraulic control system 100. When the system needs to stop working or be maintained, the double block electromagnetic valve can completely block the flow of oil in the oil inlet pipeline 120, preventing oil leakage. This reliable cut-off function is very important for some high-safety applications, such as aerospace equipment, large construction machinery, etc., which can effectively avoid equipment failure or safety accidents caused by oil leakage.

[0068] Double block electromagnetic valves usually have the characteristic of preventing reverse flow of oil, that is, the double block electromagnetic valve can control the flow of hydraulic oil from the first oil inlet 121 to the hydraulic cylinder 110, and the hydraulic oil will not leak from the hydraulic cylinder 110 to the first oil inlet 121, which can prevent the occurrence of oil reverse flow phenomenon caused by pressure fluctuation of the hydraulic control system 100 or other reasons.

[0069] When the first electromagnetic valve 130 is configured as a proportional valve, the first electromagnetic valve 130 can continuously and proportionally adjust the flow of oil in the oil inlet pipeline 120 according to the input electrical signal, which makes the movement speed of the hydraulic oil in the hydraulic cylinder 110 can be more accurately controlled, which can meet some high-precision speed control requirements of application scenarios, such as the feed system of precision machine tools, the mold closing system of injection molding machines, etc.

[0070] Please refer to Figure 2 In other embodiments, the hydraulic control system 100 further comprises a one-way valve 170, which is arranged between the first electromagnetic valve 130 and the first oil inlet 121.

[0071] The one-way valve 170 can prevent the backflow of hydraulic oil, and the arrangement of the one-way valve 170 between the first electromagnetic valve 130 and the first oil inlet 121 can ensure that the hydraulic oil can only flow from the first oil inlet 121 to the first electromagnetic valve 130 and the hydraulic cylinder 110, avoiding damage to the components of the hydraulic control system 100 caused by backflow of oil, such as preventing the reverse rotation of the oil pump.

[0072] When the hydraulic control system 100 stops running, the one-way valve 170 can prevent the hydraulic oil in the hydraulic cylinder 110 from flowing back to the oil pump, so that the outlet of the oil pump maintains a certain pressure, which can reduce the air suction phenomenon of the oil pump when the oil pump is started next time, reduce the starting load of the oil pump, prolong the service life of the oil pump, and improve the use stability and reliability of the hydraulic control system 100.

[0073] In addition, in some embodiments, when the pressure of the first oil inlet 121 suddenly changes, the one-way valve 170 can prevent the hydraulic oil from flowing in the opposite direction, so that the pressure in the hydraulic cylinder 110 does not decrease rapidly due to the sudden decrease in the pressure of the first oil inlet 121, thereby keeping the pressure in the hydraulic control system 100 relatively stable.

[0074] For example, when the first electromagnetic valve 130 is closed, the one-way valve 170 can prevent the hydraulic oil from flowing back from the hydraulic cylinder 110 or other parts to the first oil inlet 121, even if the first electromagnetic valve 130 fails or leaks, the one-way valve 170 can ensure that the hydraulic control system 100 is in a reliable closed state, and when the first electromagnetic valve 130 is opened, the one-way valve 170 allows the hydraulic oil to flow from the first oil inlet 121 to the hydraulic cylinder 110, ensuring the normal operation of the hydraulic control system 100.

[0075] Please refer to Figure 1 Or Figure 2 In this embodiment, the hydraulic control system 100 includes a filter screen 180, which is arranged in the oil return pipeline 140 between the second electromagnetic valve 160 and the first end 141.

[0076] The filter screen 180 can effectively intercept various impurities in the oil return pipeline 140, such as metal chips, rubber particles, dust, etc. If these impurities enter other elements of the hydraulic control system 100 (such as the compensation type proportional flow valve 150, the second electromagnetic valve 160, etc.), it may cause the elements to wear, jam or block, affecting their normal working performance and service life. By arranging the filter screen 180 between the second electromagnetic valve 160 and the first end 141, the impurities in the hydraulic oil flowing from the first end 141 to the first oil return port 143 can be filtered out, making the hydraulic oil entering the subsequent elements cleaner, thereby protecting these precision elements and reducing the probability of failure. Moreover, filtering out impurities in the return oil can reduce the degree of pollution of the hydraulic oil. Clean hydraulic oil can better perform its lubricating, cooling and power transmission functions, reduce the oxidation and deterioration rate of the hydraulic oil caused by impurities, extend the service life of the hydraulic oil, and reduce the frequency and cost of replacing the hydraulic oil.

[0077] For the compensation type proportional flow valve 150, it has a higher requirement for the cleanliness of the hydraulic oil, and the filter screen 180 arranged in the oil return pipeline 140 can effectively prevent impurities from entering the compensation type proportional flow valve 150, ensuring that it can accurately adjust the return oil flow, maintain the stable flow and pressure compensation function of the hydraulic control system 100. Avoiding the influence of impurities on the action of the spool of the compensation type proportional flow valve 150, ensuring the control accuracy and response speed of the hydraulic control system 100.

[0078] Please refer to Figures 1 to 3In the embodiment, the compensation type proportional flow valve 150 is configured as a two-way compensation type proportional flow valve or a three-way compensation type proportional flow valve.

[0079] The two-way compensation type proportional flow valve has a relatively simple structure and a simple internal structure, and requires fewer components in the manufacturing process, which makes the manufacturing cost relatively low. For some cost-sensitive hydraulic system application scenarios, such as small mechanical equipment and simple automation devices, the use of a two-way compensation type proportional flow valve can effectively reduce the overall cost of the system while meeting the basic flow control requirements.

[0080] Due to the relatively simple structure of the two-way compensation type proportional flow valve, the spool of the two-way compensation type proportional flow valve is more sensitive and has a faster response speed. When the control signal of the hydraulic control system 100 changes, the valve opening can be quickly adjusted to change the flow rate, so that the hydraulic control system 100 can quickly respond to external instructions and improve the working efficiency and dynamic performance of the hydraulic control system 100.

[0081] The three-way compensation type proportional flow valve can not only achieve proportional control of the flow rate, but also coordinate the pressure and flow rate between the three ports. It can automatically adjust the oil distribution of the three ports according to the load of the hydraulic control system 100, so that the pressure and flow rate of the working port can meet the requirements of the actuator. If a three-way compensation type proportional flow valve is used, closing two ports of the three-way compensation type proportional flow valve can achieve the same effect as a two-way proportional flow valve

[0082] According to different usage requirements, the compensation type proportional flow valve 150 can be configured as a two-way compensation type proportional flow valve or a three-way compensation type proportional flow valve.

[0083] Specifically, the compensation type proportional flow valve 150 is configured as a two-way compensation type proportional flow valve or a three-way compensation type proportional flow valve, and the compensation type proportional flow valve 150 can adjust the flow rate of the hydraulic oil flowing through the compensation type proportional flow valve 150, thereby adjusting the movement speed of the goods.

[0084] Please refer to Figures 1 to 3 In the embodiment, the compensation type proportional flow valve 150 includes a proportional adjustment part 151 and a pressure compensation part 152, the proportional adjustment part 151 is arranged between the pressure compensation part 152 and the second electromagnetic valve 160, and the compensation type proportional flow valve 150 further includes a compensation oil path 190, one end of the compensation oil path 190 is in communication with the inlet of the proportional adjustment part 151, and the other end of the compensation oil path 190 is in communication with the outlet of the proportional adjustment part 151.

[0085] The proportional adjusting part 151 is used to adjust the flow size of the hydraulic oil, and the pressure compensation part 152 is used to adjust the pressure size of the hydraulic oil at the inlet and outlet of the proportional adjusting part 151. The proportional adjusting part 151 has an inlet and an outlet. The inlet of the proportional adjusting part 151 is in communication with one end of the compensation oil line 190, and the inlet of the proportional adjusting part 151 is in communication with the first end 141 of the oil return line 140. The outlet of the proportional adjusting part 151 is in communication with the compensation oil line 190. For example, at least part of the pressure compensation part 152 can belong to a part of the compensation oil line 190, so that the pressure of the hydraulic oil at both ends of the inlet and outlet of the proportional adjusting part 151 can be balanced, and the stability and reliability of the operation of the hydraulic control system 100 are improved.

[0086] The pressure compensation part 152 can sense the pressure change of the inlet of the proportional adjusting part 151 in real time. When the hydraulic control system 100 has pressure fluctuation, the pressure compensation part 152 can quickly respond to adjust the valve opening to balance the pressure change, avoid the flow mutation caused by the pressure fluctuation, reduce the vibration and impact of the hydraulic oil on the hydraulic control system 100, and make the hydraulic control system 100 operate more smoothly.

[0087] Please refer to Figure 4 Another embodiment of the present application provides a hydraulic control system 100, which comprises a hydraulic oil cylinder 110, an oil inlet line 120, a first electromagnetic valve 130, an oil return line 140, a proportional adjusting valve 200, a pressure compensation valve 210, and a second electromagnetic valve 160. One end of the oil inlet line 120 is configured as a first oil inlet port 121, and the other end of the oil inlet line 120 is in communication with the hydraulic oil cylinder 110. The first electromagnetic valve 130 is arranged in the oil inlet line 120 and located between the first oil inlet port 121 and the hydraulic oil cylinder 110. The oil return line 140 has a first end 141 and a second end 142. The first end 141 of the oil return line 140 is in communication with the hydraulic oil cylinder 110, or the first end 141 of the oil return line 140 is in communication with the oil inlet line 120 and located between the first electromagnetic valve 130 and the hydraulic oil cylinder 110. The second end 142 of the oil return line 140 is configured as a first oil return port 143. The proportional adjusting valve 200 and the pressure compensation valve 210 are arranged in the oil return line 140. The pressure compensation valve 210 is arranged between the proportional adjusting valve 200 and the first oil return port 143. The inlet of the proportional adjusting valve 200 is connected with the outlet of the proportional adjusting valve 200 through the compensation oil line 190. The second electromagnetic valve 160 is arranged in the compensation oil line 190 or arranged in the oil return line 140 and located between the proportional adjusting valve 200 and the first end 141.

[0088] The proportional regulating valve 200 and the pressure compensation valve 210 are arranged in the oil return pipeline 140. The proportional regulating valve 200 is used to regulate the flow in the oil return pipeline 140. The pressure compensation valve 210 is arranged between the proportional regulating valve 200 and the first oil return port 143. The two ends of the proportional regulating valve 200, i.e. the inlet of the proportional regulating valve 200 and the outlet of the proportional regulating valve 200, are connected with the compensation oil line 190. At least part of the pressure compensation valve 210 belongs to the compensation oil line 190. In this way, the pressure compensation valve 210 can perform pressure balance regulation on the hydraulic oil at the inlet and outlet of the proportional regulating valve 200, thereby improving the stability and reliability of the hydraulic control system 100.

[0089] For example, the second electromagnetic valve 160 is arranged in the compensation oil line 190. The second electromagnetic valve 160 can control the opening and closing of the compensation oil line 190. When the hydraulic control system 100 is in the cargo load maintaining state, the second electromagnetic valve 160 can be closed to disconnect the compensation oil line 190, and the proportional regulating valve 200 can be closed. In this way, the hydraulic oil cannot flow to the pressure compensation valve 210, and the hydraulic oil cannot leak from the pressure compensation valve 210. The second electromagnetic valve 160 is arranged in the oil return pipeline 140 and located between the proportional regulating valve 200 and the first end 141. In this way, the second electromagnetic valve 160 can control the opening and closing of the oil return pipeline 140. When the hydraulic control system 100 is in the cargo load maintaining state, the second electromagnetic valve 160 can be closed to disconnect the communication between the pressure compensation valve 210 and the hydraulic oil cylinder 110. In this way, the hydraulic oil in the hydraulic oil cylinder 110 cannot flow to the pressure compensation valve 210, and the hydraulic oil cannot leak from the pressure compensation valve 210. This can improve the stability and reliability of the hydraulic control system 100.

[0090] In some embodiments, the first end 141 of the oil return pipeline 140 is directly communicated with the hydraulic oil cylinder 110, i.e. the hydraulic oil can directly flow from the hydraulic oil cylinder 110 to the first end 141 of the oil return pipeline 140 without passing through the oil inlet pipeline 120.

[0091] Please refer to Figure 4 In this embodiment, the first electromagnetic valve 130 is configured as a double block electromagnetic valve or a proportional valve.

[0092] When the first electromagnetic valve 130 is configured as a double block electromagnetic valve, it can provide a more reliable oil line cut-off function for the hydraulic control system 100. When the system needs to stop working or be maintained, the double block electromagnetic valve can completely block the flow of oil in the oil inlet pipeline 120 to prevent oil leakage. This reliable cut-off function is very important for some occasions with high safety requirements, such as aerospace equipment and large engineering machinery, which can effectively avoid equipment failure or safety accidents caused by oil leakage.

[0093] The double block solenoid valve generally has the characteristics of preventing the reverse flow of oil, that is, the double block solenoid valve can control the flow of hydraulic oil from the first oil inlet 121 to the hydraulic cylinder 110, and the hydraulic oil cannot leak from the hydraulic cylinder 110 to the first oil inlet 121, which can prevent the occurrence of oil reverse flow phenomenon caused by pressure fluctuation of the hydraulic control system 100 or other reasons.

[0094] The first solenoid valve 130 is configured as a proportional valve, which can continuously and proportionally adjust the flow of oil in the oil inlet pipeline 120 according to the input electrical signal, which makes the movement speed of the hydraulic oil in the hydraulic cylinder 110 more accurately controlled, and can meet some application scenarios with extremely high requirements for speed control accuracy, such as the feed system of precision machine tools and the mold closing system of injection molding machines.

[0095] Please refer to Figure 4 In this embodiment, the hydraulic control system 100 includes a filter screen 180, which is arranged in the oil return pipeline 140 between the proportional regulating valve 200 and the first end 141.

[0096] The filter screen 180 can effectively intercept various impurities in the oil return pipeline 140, such as metal chips, rubber particles, dust, etc. If these impurities enter other elements of the hydraulic control system 100 (proportional regulating valve 200, pressure compensation valve 210, etc.), they may cause element wear, jamming or blockage, affecting their normal working performance and service life. By arranging the filter screen 180 between the proportional regulating valve 200 and the first end 141, the impurities in the hydraulic oil flowing from the first end 141 to the first oil return port 143 can be filtered out, making the hydraulic oil entering the subsequent elements cleaner, thereby protecting these precision elements and reducing the probability of failure. Moreover, filtering out impurities in the oil return can reduce the degree of pollution of the hydraulic oil. Clean hydraulic oil can better play its role in lubrication, cooling and power transmission, reduce the oxidation and deterioration speed of the hydraulic oil caused by impurities, prolong the service life of the hydraulic oil, and reduce the frequency and cost of replacing the hydraulic oil.

[0097] For the proportional regulating valve 200 and the pressure compensation valve 210, the cleanliness of the hydraulic oil is required to be higher, and the filter screen 180 is arranged in the oil return pipeline 140, which can effectively prevent impurities from entering the proportional regulating valve 200 and the pressure compensation valve 210, ensuring that they can accurately regulate the oil return flow and maintain the normal operation of the flow stability and pressure compensation function of the hydraulic control system 100. Avoiding the influence of impurities on the valve core action of the pressure compensation valve 210 and the proportional regulating valve 200, ensuring the control accuracy and response speed of the hydraulic control system 100.

[0098] Please refer to Figure 4 In some embodiments, a one-way valve 170 is arranged between the first solenoid valve 130 and the first oil inlet 121.

[0099] Please refer to Figures 1 to 5 The embodiment provides a forklift 1000, which comprises the hydraulic control system 100 of any one of the embodiments.

[0100] The forklift 1000 provided by the embodiment can avoid the probability of oil leakage at the pressure compensation part 152 or the pressure compensation valve 210 of the hydraulic control system 100 when the forklift 1000 holds a load, and improve the stability and reliability of the forklift 1000.

[0101] It should also be noted that the terms "comprising", "containing", or any other variant thereof are intended to cover a non-exclusive inclusion, such that a process, method, article or apparatus that comprises a list of elements does not include only those elements, but can also include other elements not expressly listed or inherent to such process, method, article or apparatus. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article or apparatus that includes the element.

[0102] Each of the embodiments in the specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other. Each embodiment focuses on the difference from other embodiments. In particular, the system embodiment is basically similar to the method embodiment, so the description is relatively simple, and the relevant parts can be referred to the part of the method embodiment.

[0103] The above only describes the embodiments of the present application and does not limit the present application. Those skilled in the art can make various modifications and changes to the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the scope of claims of the present application.

[0104] Although the embodiments of the present application are described in conjunction with the drawings, those skilled in the art can make various modifications and changes without departing from the spirit and scope of the present application, and such modifications and changes fall within the scope defined by the appended claims.

Claims

1. A hydraulic control system characterized by, The hydraulic control system comprises: a hydraulic cylinder (110); an oil inlet pipeline (120), one end of the oil inlet pipeline (120) being configured as a first oil inlet (121), the other end of the oil inlet pipeline (120) being communicated with the hydraulic cylinder (110); a first electromagnetic valve (130) arranged in the oil inlet pipeline (120) and located between the first oil inlet (121) and the hydraulic cylinder (110); an oil return pipeline (140), the oil return pipeline (140) having a first end (141) and a second end (142), the first end (141) of the oil return pipeline (140) being communicated with the hydraulic cylinder (110) or the first end (141) of the oil return pipeline (140) being communicated with the oil inlet pipeline (120) and located between the first electromagnetic valve (130) and the hydraulic cylinder (110), the second end (142) of the oil return pipeline (140) being configured as a first oil return port (143); a compensation type proportional flow valve (150) and a second electromagnetic valve (160) arranged in the oil return pipeline (140), the compensation type proportional flow valve (150) being located between the second electromagnetic valve (160) and the first oil return port (143), the second electromagnetic valve (160) being capable of selectively blocking the oil return pipeline (140).

2. The hydraulic control system of claim 1, wherein, The first electromagnetic valve (130) is configured as a double-stop electromagnetic valve or a proportional valve.

3. The hydraulic control system of claim 1, wherein, The hydraulic control system further comprises a check valve (170) arranged between the first electromagnetic valve (130) and the first oil inlet (121).

4. The hydraulic control system of claim 1, wherein, The hydraulic control system comprises a filter screen (180) arranged in the oil return pipeline (140) and located between the second electromagnetic valve (160) and the first end (141).

5. The hydraulic control system of claim 1, wherein, The compensation type proportional flow valve (150) is configured as a two-way compensation type proportional flow valve or a three-way compensation type proportional flow valve.

6. The hydraulic control system of claim 1, wherein, The compensation type proportional flow valve (150) comprises a proportional adjusting part (151) and a pressure compensation part (152), the proportional adjusting part (151) being arranged between the pressure compensation part (152) and the second electromagnetic valve (160), the compensation type proportional flow valve (150) further comprising a compensation oil path (190), one end of the compensation oil path (190) being communicated with an inlet of the proportional adjusting part (151), the other end of the compensation oil path (190) being communicated with an outlet of the proportional adjusting part (151).

7. A hydraulic control system characterized by, The hydraulic control system comprises: a hydraulic cylinder (110); an oil inlet pipeline (120), one end of the oil inlet pipeline (120) being configured as a first oil inlet (121), the other end of the oil inlet pipeline (120) being communicated with the hydraulic cylinder (110); a first electromagnetic valve (130) arranged in the oil inlet pipeline (120) and located between the first oil inlet (121) and the hydraulic cylinder (110); An oil return pipeline (140) having a first end (141) and a second end (142), the first end (141) of the oil return pipeline (140) being in communication with the hydraulic cylinder (110), or the first end (141) of the oil return pipeline (140) being in communication with the oil inlet pipeline (120) and being located between the first electromagnetic valve (130) and the hydraulic cylinder (110), the second end (142) of the oil return pipeline (140) being configured as a first oil return port (143); A proportional regulating valve (200) and a pressure compensation valve (210) are provided in the oil return pipeline (140), the pressure compensation valve (210) being provided between the proportional regulating valve (200) and the first oil return port (143), the inlet of the proportional regulating valve (200) being connected to the outlet of the proportional regulating valve (200) through a compensation oil path (190); A second electromagnetic valve (160) is provided in the compensation oil path (190) or in the oil return pipeline (140) and located between the proportional regulating valve (200) and the first end (141).

8. The hydraulic control system of claim 7, wherein, The first electromagnetic valve (130) is configured as a double-stop electromagnetic valve or a proportional valve.

9. The hydraulic control system of claim 7, wherein, The hydraulic control system comprises a filter screen (180) provided in the oil return pipeline (140) and located between the proportional regulating valve (200) and the first end (141).

10. A fork lift truck characterised by The hydraulic control system of any one of claims 1-6 or the hydraulic control system of any one of claims 7-9.

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