Hydraulic control system for achieving preheating and heat preservation of hydraulic system of engineering vehicle, using method and engineering vehicle

Abstract

A hydraulic control system for achieving preheating and heat preservation of a hydraulic system of an engineering vehicle, a using method and the engineering vehicle comprise a hydraulic pump, and the hydraulic pump is connected with a pump control oil way, a forced heating oil way, an overflow oil way, a hydraulic pump preheating oil way, a walking hydraulic oil way, a rotation hydraulic oil way and a heat dissipation oil way. One ends of the pump control oil way, the forced heating oil way and the overflow oil way are connected with an oil supply way of the hydraulic pump I, the other ends of the pump control oil way, the forced heating oil way and the overflow oil way are connected with a hydraulic oil tank, and an immersion heating assembly is arranged on the hydraulic oil tank. By comparing the preset temperature threshold interval of the hydraulic oil with the actual temperature value detected by the temperature sensor, on-off of the oil way switching valve is adjusted in different control modes, switching work of an off-line oil way and an on-line oil way is achieved, the system pressure is limited through the overflow valve, the efficiency of the preheating and heat preservation process is improved, and the working efficiency is improved. The stable operation of the engineering vehicle in the cold environment is guaranteed, and meanwhile energy consumption is reduced.

Description

Technical Field

[0001] This invention relates to the field of engineering machinery technology, specifically a hydraulic control system, a method of use, and an engineering vehicle for preheating and heat preservation of the hydraulic system. Background Technology

[0002] In cold regions (such as high-latitude permafrost areas and areas with severe winters), the hydraulic systems of engineering vehicles (represented by hydraulic excavators, loaders, and crawler cranes) have long faced multiple technical bottlenecks caused by the low-temperature environment. These problems not only directly affect the operating efficiency of the equipment, but also exacerbate component wear, shorten the service life of the whole machine, and even cause safety accidents. They have become one of the core pain points restricting the efficiency of engineering construction in cold regions.

[0003] From the perspective of the mechanism of the impact of low temperature on hydraulic systems, the primary problem is the abnormal change in hydraulic oil viscosity. The viscosity of hydraulic oil is significantly negatively correlated with temperature. This change directly triggers two major chain reactions: First, the hydraulic pump's suction resistance increases, which can easily lead to negative pressure in the suction chamber, allowing air to seep into the oil and form cavitation, causing "cavitation phenomenon"; second, the oil flow rate slows down, resulting in a delay in the response of hydraulic actuators, making it difficult to meet the requirements of precision operations.

[0004] Secondly, low temperatures can cause irreversible damage to the sealing performance and precision-fitting components of hydraulic systems. Hydraulic components often use seals made of elastic materials such as nitrile rubber and fluororubber. The elastic modulus of these materials increases significantly as temperature decreases, leading to reduced sealing surface fit and making oil leakage highly likely. Simultaneously, the valve core and valve sleeve in hydraulic valve assemblies are often precisely fitted. At low temperatures, metal parts shrink due to thermal expansion and contraction, causing abnormally large clearances and potentially leading to valve core jamming or decreased flow control accuracy.

[0005] In existing technologies, some systems are equipped with offline heating and insulation loops. Preheated hydraulic oil is delivered to the hydraulic tank and hydraulic pump through a forced heating device in the loop to mitigate the adverse effects of low temperature. However, the preheating and insulation range of existing systems is limited, and they do not achieve full coverage of key components such as rotary hydraulic motors, travel hydraulic motors, and center rotary joints. Furthermore, they lack a precise control mechanism that dynamically switches control modes based on temperature, and their control efficiency and reliability need to be improved. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a hydraulic control system, a method of use and an engineering vehicle for preheating and heat preservation of the hydraulic system of engineering vehicles. This invention solves the problems of poor oil flow, component leakage and reduced control accuracy caused by low temperature in the hydraulic system of engineering vehicles in cold regions. It achieves precise preheating and heat preservation of all key components of the hydraulic system and improves control reliability, energy saving and efficiency.

[0007] The present invention is achieved by the following technical solution: a hydraulic control system for preheating and heat preservation of the hydraulic system of an engineering vehicle, comprising a hydraulic pump I and a hydraulic pump II. The hydraulic pump I is connected to a hydraulic pump preheating oil circuit, a travel hydraulic oil circuit, a rotation hydraulic oil circuit and a cooling oil circuit through a reversing valve II. A pump control oil circuit, a forced heating oil circuit and an overflow oil circuit are also provided between the hydraulic pump I and the reversing valve II. One end of the pump control oil circuit, the forced heating oil circuit and the overflow oil circuit is connected to the oil supply circuit of the hydraulic pump I, and the other end is connected to the hydraulic oil tank. The hydraulic oil tank is equipped with an immersion heating component. The pump control circuit includes a reversing valve I connected to the outlet of hydraulic pump I; Forced heating oil circuit, including check valve and forced heating device; Overflow oil passage, including overflow valve; The hydraulic pump preheating oil circuit includes a reversing valve III and a one-way throttle valve. The hydraulic pump preheating oil circuit is connected to the first pressure relief port of hydraulic pump I and hydraulic pump II. The second oil relief port of hydraulic pump I and hydraulic pump II is connected to the hydraulic oil tank. The travel hydraulic circuit includes directional valve V, a center rotary joint, and a travel hydraulic motor; The rotary hydraulic circuit includes directional valve IV, main valve, and rotary hydraulic motor; Cooling oil circuit; including fan motor; It also includes a controller, the input of which is connected to a temperature sensor for detecting the oil temperature in the hydraulic tank; the output of the controller is connected to directional valve I, relief valve, directional valve II, directional valve III, directional valve IV and directional valve V.

[0008] Furthermore, the hydraulic pump I is a load-sensitive variable pump.

[0009] The hydraulic pump I has a damping orifice I at its outlet, and the directional valve I has a damping orifice II at its inlet.

[0010] The reversing valves I, III, IV and V are two-position two-way solenoid reversing valves. When the reversing valve I is not energized, it is in the conducting position, and when the reversing valves III, IV and V are not energized, they are in the disconnected position.

[0011] The reversing valve II is a two-position three-way solenoid reversing valve. The reversing valve II is divided into two paths after the valve. One path is connected to the hydraulic pump preheating oil path, the travel hydraulic oil path, and the slewing hydraulic oil path. The other path is connected to the cooling oil path.

[0012] The oil outlets of the reversing valve III and reversing valve V are both connected to one-way throttle valves, the oil inlet of the rotary hydraulic motor is connected to a one-way throttle valve, and the control ends of each valve core in the main valve are all connected to one-way throttle valves.

[0013] The overflow valve has two overflow pressure values.

[0014] The method for using a hydraulic control system to achieve preheating and heat preservation of the hydraulic system of an engineering vehicle includes a cold start preheating stage, a shutdown heat preservation stage, and a running preheating stage. Preset temperatures T0, T1, and T2 are input to the controller, where T0 < T1 < T2. The relief valve has a first preset pressure value and a second preset pressure value, where the first preset pressure value is greater than the second preset pressure value. The specific steps are as follows: Cold start warm-up phase: S1. The operator operates the immersion heating components and forced heating device; S2, The engineering vehicle operator sends a preheating and insulation start command to the controller; S3. When the temperature detected by the temperature sensor is between [-45℃, T0], the controller controls the overflow valve to be at the first preset pressure value; S4. When the temperature detected by the temperature sensor is between (T0, T1), the controller controls the overflow valve to the second preset pressure value and controls the reversing valve III to be in the open position. Shutdown and heat preservation stage: T1. Operator operates the immersion heating components and forced heating device; T2. The engineering vehicle operator sends a preheating and insulation start command to the controller; T3. When the temperature detected by the temperature sensor is greater than T1, the controller controls the reversing valve III to be in the open position and the reversing valves IV and V to be in the open position, and the hydraulic oil is delivered to the hydraulic pump I, hydraulic pump II, rotary hydraulic motor, travel hydraulic motor, center rotary joint and main valve. Preheating phase: E1. Operator stops the immersion heating assembly and forced heating device; E2. After the engineering vehicle is in operation, the engineering vehicle operator sends a preheating and insulation start command to the controller; E2. When the temperature detected by the temperature sensor is between (T1, T2), the controller controls the relief valve to the second preset pressure value, controls the directional valve I to switch to the off position with a delay, and controls the directional valves IV and V to be in the on position, so as to realize the hydraulic oil delivery to the rotary hydraulic motor, the travel hydraulic motor, the center rotary joint and the main valve.

[0015] The preheating phase also includes a heat dissipation phase, with the following specific steps: P1. The engineering vehicle operator sends a preheating and insulation stop command to the controller. P2. When the temperature detected by the temperature sensor is greater than T2, the controller controls the reversing valve II to switch to the working position and controls the reversing valve I to remain in the open position. At this time, the hydraulic oil drives the fan motor for heat dissipation.

[0016] An engineering vehicle includes a hydraulic control system for preheating and heat preservation of the hydraulic system of the engineering vehicle according to any one of the above-mentioned methods, wherein the engineering vehicle is a hydraulic excavator, and the hydraulic excavator uses the hydraulic control system for preheating and heat preservation of the hydraulic system of the engineering vehicle according to any one of the above-mentioned methods.

[0017] The present invention has the following advantages: The hydraulic control system, usage method, and engineering vehicle of the present invention realize the preheating and heat preservation of the hydraulic system of engineering vehicles. By comparing the preset temperature threshold range of hydraulic oil with the actual temperature value detected by the temperature sensor, the on / off state of the oil circuit switching valve is adjusted in different control modes to realize the switching of offline oil circuit and online oil circuit. The system pressure is limited by the relief valve to improve the efficiency of the preheating and heat preservation process. Through flexible control mode switching and pressure regulation, the hydraulic system can achieve efficient preheating and reliable heat preservation in different stages such as cold start, operation and shutdown, ensuring the stable operation of engineering vehicles in cold environments, while reducing energy consumption. Attached Figure Description

[0018] The accompanying drawings, as part of this invention, are provided to further illustrate the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention, but do not constitute an undue limitation thereof. Clearly, the drawings described below are merely some embodiments, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0019] In the attached diagram: Figure 1 This is a hydraulic schematic diagram of the present invention; Figure 2 This is a flowchart of the control process for offline oil circuit preheating and insulation control according to the present invention; Figure 3 This is a flowchart of the control process for online oil circuit preheating and insulation control according to the present invention.

[0020] In the diagram: 1. Hydraulic pump I, 2. Forced heating device, 3. Check valve, 4. Fan motor, 5. Damping orifice I, 6. Damping orifice II, 7. Directional valve I, 8. Relief valve, 9. Immersion heating component, 10. Controller, 11. Central rotary joint, 12. Temperature sensor, 13. Hydraulic oil tank, 14. Directional valve II, 15. Directional valve III, 16. Directional valve IV, 17. Directional valve V, 18. Hydraulic pump II, 19. One-way throttle valve, 20. Travel hydraulic motor, 21. Main valve, 22. Rotary hydraulic motor.

[0021] It should be noted that these accompanying drawings and textual descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0023] In the description of this invention, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0024] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0025] like Figures 1 to 3 The hydraulic control system shown is for preheating and heat preservation of the hydraulic system of an engineering vehicle. It includes a hydraulic pump I1 and a hydraulic pump II18. The hydraulic pump I1 is connected to a hydraulic pump preheating oil circuit, a travel hydraulic oil circuit, a slewing hydraulic oil circuit and a cooling oil circuit through a reversing valve II14. A pump control oil circuit, a forced heating oil circuit and an overflow oil circuit are also provided between the hydraulic pump I1 and the reversing valve II14. One end of the pump control oil circuit, the forced heating oil circuit and the overflow oil circuit is connected to the oil supply circuit of the hydraulic pump I1, and the other end is connected to the hydraulic oil tank 13. The hydraulic oil tank 13 is equipped with an immersion heating component 9. The hydraulic control system of the present invention for preheating and heat preservation of the hydraulic system of engineering vehicles includes a hydraulic pump, a hydraulic oil tank, a pump control oil circuit, a forced heating oil circuit, an overflow oil circuit, a hydraulic pump preheating oil circuit, a travel hydraulic oil circuit, a slewing hydraulic oil circuit, and a cooling oil circuit. It is further divided into offline oil circuits and online oil circuits. The offline oil circuits include a forced heating oil circuit, an overflow oil circuit, and multiple directional valves, which are used to provide hydraulic oil for preheating and heat preservation of the vehicle when the vehicle is not started. The online oil circuits include a hydraulic pump, a travel hydraulic oil circuit, and a slewing hydraulic oil circuit, which are used to provide hydraulic oil for preheating and heat preservation of the vehicle when the vehicle is started.

[0026] Specifically, the offline oil circuit 103 includes a forced heating device, an overflow valve, and directional valves II14, III15, IV16, and V17 that supply preheated hydraulic oil to the hydraulic oil tank, hydraulic pump I and hydraulic pump II, rotary hydraulic motor, travel hydraulic motor, center rotary joint, and main valve.

[0027] The online oil circuit 101 includes hydraulic pump I and oil circuit switching valves I7, II14, IV16 and V17 that supply preheated hydraulic oil to the rotary hydraulic motor, the travel hydraulic motor, the center rotary joint and the main valve.

[0028] like Figure 1 The hydraulic control system shown is for preheating and heat preservation of the hydraulic system of an engineering vehicle. The pump control circuit includes a reversing valve I7 connected to the outlet of hydraulic pump I1. Hydraulic pump I1 is a load-sensitive variable displacement pump. The outlet of hydraulic pump I1 is provided with a damping orifice I5, and the inlet of reversing valve I7 is provided with a damping orifice II6. The hydraulic pump I of this invention is a load-sensitive variable displacement pump, including a displacement regulating device 1a for changing the displacement of hydraulic pump I. Additionally, reversing valve I is used to regulate the output pressure of feedback oil circuit 101, so that the displacement regulating mechanism 1a of hydraulic pump I adjusts the output flow rate according to the change in the output pressure of feedback oil circuit 101. Specifically, the outlet of hydraulic pump I is connected to the hydraulic oil tank in sequence through damping orifice I, damping orifice II, and reversing valve I. The response of reversing valve I7 regulates the fluid pressure formed by flowing through damping orifice I and damping orifice II. The pressurized fluid is fed back to the displacement regulating device 1a of hydraulic pump I via oil circuit 101, pumping hydraulic oil 13a to the online oil circuit 102.

[0029] like Figure 1 The hydraulic control system shown is for preheating and heat preservation of the hydraulic system of engineering vehicles. The forced heating oil circuit includes a one-way valve 3 and a forced heating device 2. The forced heating device of this invention has its suction port connected to the hydraulic oil tank, supplying hydraulic oil 13a to the offline oil circuit 103.

[0030] like Figure 1 The hydraulic control system shown realizes the preheating and heat preservation of the hydraulic system of the engineering vehicle. The oil circuit 104 is used as an oil circuit formed by connecting the downstream side of the online oil circuit 102 and the downstream side of the offline oil circuit 103 in series.

[0031] like Figure 1 The hydraulic control system shown is used to preheat and maintain the temperature of the hydraulic system of an engineering vehicle. The system includes an overflow circuit, comprising an overflow valve 8. The overflow valve 8 has two overflow pressure settings. The inlet of the overflow valve is connected to oil circuit 104, and the outlet is connected to the hydraulic oil tank. It provides a pressure value that limits the system pressure for offline oil circuit 103 or online oil circuit 102, including but not limited to a first preset pressure value or a second preset pressure value.

[0032] like Figure 1 The hydraulic control system shown is for preheating and heat preservation of the hydraulic system of an engineering vehicle. The reversing valve II14 is a two-position three-way solenoid reversing valve. The reversing valve II14 is divided into two paths after the valve. One path connects to the hydraulic pump preheating oil path, the travel hydraulic oil path, and the slewing hydraulic oil path. The other path connects to the cooling oil path. The reversing valve II14 of this invention is used to control the hydraulic oil supplied by the oil path 104 to supply oil to the two oil paths. One path flows from the first operating position X1 of the reversing valve II14 to the oil path 107, which supplies oil to the hydraulic pump preheating oil path, the travel hydraulic oil path, and the slewing hydraulic oil path, respectively. The other oil path flows through the second operating position X2 of the reversing valve II14 to the oil path 32, which supplies oil to the cooling oil path.

[0033] like Figure 1 The hydraulic control system shown is for preheating and heat preservation of the hydraulic system of an engineering vehicle. The hydraulic pump preheating circuit includes a reversing valve III 15 and a one-way throttle valve 19. This preheating circuit is connected to the first pressure relief ports of hydraulic pumps I 1 and II 18, and the second pressure relief ports of hydraulic pumps I 1 and II 18 are connected to the hydraulic oil tank 13. The outlet of the reversing valve III 15 is connected to the one-way throttle valve 19. The inlet of the reversing valve III 15 is connected to oil circuit 107 to control the hydraulic oil 13a supplied by oil circuit 107 to pass through the first operating position X1 of the reversing valve II 14 to oil circuit 104. The inlet of the one-way throttle valve is connected to oil circuit 104, and the outlet of the one-way throttle valve is connected to the first pressure relief ports of hydraulic pumps I and II. The second pressure relief ports of hydraulic pumps I and II are connected to the hydraulic oil tank.

[0034] like Figure 1 The hydraulic control system shown is for preheating and heat preservation of the hydraulic system of an engineering vehicle. The travel hydraulic circuit includes a reversing valve V17, a central rotary joint 11, and a travel hydraulic motor 20. The outlet of the reversing valve V17 is connected to a one-way throttle valve 19. The inlet of the reversing valve V17 is connected to oil circuit 107 to control the hydraulic oil supplied by oil circuit 107 to pass through the first operating position X1 of the reversing valve II14 to oil circuit 105. The inlet of the one-way throttle valve is connected to oil circuit 105, and the outlet of the one-way throttle valve is connected to the first port of the preheating channel 11a of the central rotary joint. The second port of the preheating channel 11a of the central rotary joint is connected to the first drain port of the travel hydraulic motor. The second drain port of the travel hydraulic motor is connected to the second port of the drain channel 11b of the central rotary joint, and the first port of the drain channel 11b of the central rotary joint is connected to the hydraulic oil tank.

[0035] like Figure 1The hydraulic control system shown is for preheating and heat preservation of the hydraulic system of an engineering vehicle. The rotary hydraulic circuit includes a directional valve IV 16, a main valve 21, and a rotary hydraulic motor 22. The inlet of the rotary hydraulic motor 22 is connected to a one-way throttle valve 19. Each valve core within the main valve 21 has a control end connected to a one-way throttle valve 19. The inlet of the directional valve IV 16 is connected to oil circuit 107 to control the hydraulic oil supplied by oil circuit 107 to flow through the first operating position X1 of the directional valve II 14 to oil circuit 106. A one-way throttle valve is provided between each control end corresponding to any valve core of the main valve and branch oil circuits 106b and 106c of oil circuit 106. A one-way throttle valve is provided between the first drain port of the rotary hydraulic motor and branch oil circuit 106a of oil circuit 106, and the second drain port is connected to the hydraulic oil tank.

[0036] like Figure 1 The hydraulic control system shown is used to preheat and maintain the temperature of the hydraulic system of the engineering vehicle, including a cooling oil circuit and a fan motor 4.

[0037] like Figure 1 The hydraulic control system for preheating and maintaining the temperature of the hydraulic system of an engineering vehicle, as shown, further includes a controller 10. The input terminal of the controller 10 is connected to a temperature sensor 12, which is used to detect the oil temperature of the hydraulic oil tank 13. The output terminal of the controller 10 is connected to reversing valve I 7, relief valve 8, reversing valve II 14, reversing valve III 15, reversing valve IV 16, and reversing valve V 17. The controller of this invention has preset temperatures T0, T1, and T2, where T0 < T1 < T2, and a first preset pressure value and a second preset pressure value for the relief valve, where the first preset pressure value is greater than the second preset pressure value. The control principle of the controller is as follows: When the actual temperature of the hydraulic oil is lower than T0, the controller controls the relief valve to limit the pressure of the hydraulic system to a first preset pressure value, so as to adjust the preheating rate of the hydraulic oil in the offline oil circuit 103.

[0038] When the actual temperature of the hydraulic oil is higher than T0 and lower than T1, the controller controls the relief valve to limit the pressure of the hydraulic system to a second preset pressure value. At the same time, the directional valve III15 opens to realize the preheating or heat preservation of the hydraulic pump I1 and hydraulic pump II by the offline oil circuit 103.

[0039] When the actual temperature of the hydraulic oil is higher than T1 and lower than T2, the controller controls the relief valve to limit the pressure of the hydraulic system to the second preset pressure value, the reversing valves IV16 and V17 open, and the reversing valve I7 is disconnected, so as to realize the preheating or heat preservation of the rotary hydraulic motor, the travel hydraulic motor and the main valve of the online oil circuit 102.

[0040] When the actual temperature of the hydraulic oil is higher than T2, the controller controls the relief valve to limit the pressure of the hydraulic system to the second preset pressure value, the reversing valve I7 is delayed to open, the reversing valves III15, IV16 and V17 are opened, and the reversing valve II14 switches to the working position so that the online oil circuit 102 can provide oil to the fan motor for heat dissipation.

[0041] like Figure 1 The hydraulic control system shown is used to preheat and maintain the temperature of the hydraulic system of the engineering vehicle. The reversing valves I7, III15, IV16 and V17 are two-position two-way solenoid reversing valves. When the reversing valve I7 is not energized, it is in the conducting position. When the reversing valves III15, IV16 and V17 are not energized, they are in the disconnected position.

[0042] like Figures 1 to 3 The method for using a hydraulic control system to preheat and maintain the temperature of a hydraulic system in an engineering vehicle includes a cold start preheating stage, a shutdown heat preservation stage, and a running preheating stage. The controller 10 is input with preset temperatures T0, T1, and T2, where T0 < T1 < T2. The overflow valve 8 has a first preset pressure value and a second preset pressure value, where the first preset pressure value is greater than the second preset pressure value. The specific steps are as follows: Cold start warm-up phase: S1. When the engineering vehicle is in the cold start preheating stage, the operator operates the immersion heating component 9 and the forced heating device 2. S2, The engineering vehicle operator sends a preheating and insulation start command to the controller 10; S3. When the temperature detected by the temperature sensor 12 is between [-45℃, T0], the controller 10 controls the overflow valve 8 to be at the first preset pressure value; the hydraulic oil is preheated twice by the forced heating device and then overflows back to the hydraulic oil tank through the overflow valve to adjust the preheating speed of the hydraulic oil. S4. When the temperature detected by the temperature sensor 12 is between (T0, T1), the controller 10 controls the overflow valve 8 to be at the second preset pressure value and controls the reversing valve III 15 to be in the open position, so that the offline oil circuit delivers hydraulic oil to hydraulic pump I and hydraulic pump II to realize the preheating of hydraulic pump I and hydraulic pump II.

[0043] Shutdown and heat preservation stage: T1. When the engineering vehicle is in the shutdown and heat preservation stage, the operator operates the immersion heating component 9 and the forced heating device 2. T2, The engineering vehicle operator sends a preheating and insulation start command to the controller 10; T3. When the temperature detected by temperature sensor 12 is greater than T1, controller 10 controls directional valve III 15 to be in the off position and directional valve IV 16 and directional valve V 17 to be in the on position. directional valve III 15, directional valve IV 16 and directional valve V 17 switch the first operating position X1 to the first operating position X2, realizing the offline oil circuit delivery of hydraulic oil to hydraulic pump I 1, hydraulic pump II 18, rotary hydraulic motor 22, travel hydraulic motor 20, center rotary joint 11 and main valve 21. Preheating phase: E1. When the engineering vehicle is in the preheating stage, the operator stops the immersion heating component 9 and the forced heating device 2. E2. After the engineering vehicle is in operation, the engineering vehicle operator sends a preheating and insulation start command to the controller 10. E2. When the temperature detected by temperature sensor 12 is between (T1, T2), controller 10 controls relief valve 8 to be at the second preset pressure value. The relief valve limits the system pressure of the pressure fluid delivered by offline oil circuit 103 to the second preset pressure value. It controls directional valve I7 to switch to the off position with a delay, that is, directional valve I7 switches from the first operating position X1 to the second operating position X2 with a delay. It controls directional valve IV 16 and directional valve V 17 to be in the on position, that is, directional valve IV 16 and directional valve V 17 switch from the first operating position X1 to the second operating position X2, so as to realize the online oil circuit delivery of hydraulic oil to rotary hydraulic motor 22, travel hydraulic motor 20, center rotary joint 115 and main valve 21.

[0044] The preheating phase also includes a heat dissipation phase, with the following specific steps: P1, The engineering vehicle operator sends a preheating and insulation stop command to the controller 10; P2. When the temperature detected by temperature sensor 12 is greater than T2, controller 10 controls reversing valve II 14 to switch its working position, that is, reversing valve II 14 switches from the first operating position X1 to the second operating position X2, and controls reversing valve I 7 to remain in the off position, that is, reversing valve I 7 remains in the second operating position X2. At this time, hydraulic oil drives fan motor 4 for heat dissipation.

[0045] An engineering vehicle includes a hydraulic control system for preheating and heat preservation of the hydraulic system of the engineering vehicle according to any one of the above-mentioned methods, wherein the engineering vehicle is a hydraulic excavator, and the hydraulic excavator uses the hydraulic control system for preheating and heat preservation of the hydraulic system of the engineering vehicle according to any one of the above-mentioned methods.

[0046] This invention relates to a hydraulic control system, its usage method, and the engineering vehicle itself for preheating and heat preservation of the hydraulic system. By setting up offline and online oil circuits, and combining this with a control unit that flexibly switches control modes based on hydraulic oil temperature and operating conditions, and by regulating system pressure through an overflow valve, precise preheating and reliable heat preservation of the engineering vehicle's hydraulic system are achieved during different stages such as cold start, operation, and shutdown. This solution effectively solves problems such as increased hydraulic oil viscosity and decreased hydraulic component performance in cold regions, improving the operational stability and service life of the hydraulic system. Simultaneously, through coordinated temperature and pressure control, energy waste is avoided, resulting in energy-saving, high-efficiency, and reliable characteristics, making it suitable for widespread adoption and promotion in the engineering vehicle field.

[0047] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0048] Furthermore, those skilled in the art will understand that although some embodiments described herein include certain features found in other embodiments but not others, combinations of features from different embodiments are also within the scope of protection of this invention and form different embodiments. For example, in the embodiments described above, those skilled in the art can use them in combination based on known technical solutions and the technical problems to be solved by this application.

[0049] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A hydraulic control system for preheating and heat preservation of the hydraulic system of engineering vehicles, characterized in that: It includes hydraulic pump I (1) and hydraulic pump II (18). Hydraulic pump I (1) is connected to hydraulic pump preheating oil circuit, travel hydraulic oil circuit, rotation hydraulic oil circuit and heat dissipation oil circuit through reversing valve II (14). There is also a pump control oil circuit, forced heating oil circuit and overflow oil circuit between hydraulic pump I (1) and reversing valve II (14). One end of the pump control oil circuit, forced heating oil circuit and overflow oil circuit is connected to the oil supply circuit of hydraulic pump I (1), and the other end is connected to hydraulic oil tank (13). The hydraulic oil tank (13) is equipped with an immersion heating component (9). The pump control circuit includes a reversing valve I (7) connected to the oil outlet of hydraulic pump I (1); The forced heating oil circuit includes a check valve (3) and a forced heating device (2); Overflow oil circuit, including overflow valve (8); The hydraulic pump preheating oil circuit includes a reversing valve III (15) and a one-way throttle valve (19). The hydraulic pump preheating oil circuit is connected to the first pressure relief port of hydraulic pump I (1) and hydraulic pump II (18). The second oil relief port of hydraulic pump I (1) and hydraulic pump II (18) is connected to the hydraulic oil tank (13). The travel hydraulic circuit includes a directional valve V (17), a center rotary joint (11), and a travel hydraulic motor (20). The rotary hydraulic circuit includes a directional valve IV (16), a main valve (21), and a rotary hydraulic motor (22). Cooling oil circuit; including fan motor (4); It also includes a controller (10), the input of which is connected to a temperature sensor (12), which is used to detect the oil temperature of the hydraulic oil tank (13); the output of the controller (10) is connected to a reversing valve I (7), an overflow valve (8), a reversing valve II (14), a reversing valve III (15), a reversing valve IV (16) and a reversing valve V (17).

2. The hydraulic control system for preheating and heat preservation of the hydraulic system of engineering vehicles as described in claim 1, characterized in that: The hydraulic pump I (1) is a load-sensitive variable pump.

3. The hydraulic control system for preheating and heat preservation of the hydraulic system of engineering vehicles as described in claim 1, characterized in that: The hydraulic pump I (1) has a damping hole I (5) at its oil outlet end, and the directional valve I (7) has a damping hole II (6) at its oil inlet end.

4. The hydraulic control system for preheating and heat preservation of the hydraulic system of engineering vehicles as described in claim 1, characterized in that: The reversing valve I (7), reversing valve III (15), reversing valve IV (16) and reversing valve V (17) are two-position two-way solenoid reversing valves. When the reversing valve I (7) is not energized, it is in the conducting position. When the reversing valve III (15), reversing valve IV (16) and reversing valve V (17) are not energized, they are in the disconnected position.

5. The hydraulic control system for preheating and heat preservation of the hydraulic system of engineering vehicles as described in claim 1, characterized in that: The reversing valve II (14) is a two-position three-way solenoid reversing valve. The reversing valve II (14) is divided into two paths after the valve. One path is connected to the hydraulic pump preheating oil path, the walking hydraulic oil path and the slewing hydraulic oil path, and the other path is connected to the cooling oil path.

6. The hydraulic control system for preheating and heat preservation of the hydraulic system of engineering vehicles as described in claim 1, characterized in that: The oil outlets of the reversing valve III (15) and the reversing valve V (17) are connected to one-way throttle valves (19), the oil inlet of the rotary hydraulic motor (22) is connected to one-way throttle valves (19), and the control ends of each valve core in the main valve (21) are connected to one-way throttle valves (19).

7. The hydraulic control system for preheating and heat preservation of the hydraulic system of engineering vehicles as described in claim 1, characterized in that: The overflow valve (8) has two overflow pressure values.

8. The method for using the hydraulic control system for preheating and heat preservation of the hydraulic system of an engineering vehicle as described in claim 1, characterized in that: The process includes a cold start preheating stage, a shutdown heat preservation stage, and an operation preheating stage. Preset temperatures T0, T1, and T2 are input to the controller (10), where T0 < T1 < T2. The overflow valve (8) has a first preset pressure value and a second preset pressure value, where the first preset pressure value is greater than the second preset pressure value. The specific steps are as follows: Cold start warm-up phase: S1. The operator operates the immersion heating assembly (9) and the forced heating device (2). S2. The engineering vehicle operator sends a preheating and insulation start command to the controller (10). S3. When the temperature detected by the temperature sensor (12) is between [-45℃, T0], the controller (10) controls the overflow valve (8) to be at the first preset pressure value; S4. When the temperature detected by the temperature sensor (12) is between (T0, T1], the controller (10) controls the overflow valve (8) to be at the second preset pressure value and controls the reversing valve III (15) to be in the open position. Shutdown and heat preservation stage: T1. The operator operates the immersion heating assembly (9) and the forced heating device (2); T2. The engineering vehicle operator sends a preheating and insulation start command to the controller (10). T3. When the temperature detected by the temperature sensor (12) is greater than T1, the controller (10) controls the reversing valve III (15) to be in the open position, and the reversing valve IV (16) and the reversing valve V (17) to be in the open position. The hydraulic oil is delivered to the hydraulic pump I (1), the hydraulic pump II (18), the rotary hydraulic motor (22), the travel hydraulic motor (20), the center rotary joint (11), and the main valve (21). Preheating phase: E1. Operator stops immersion heating assembly (9) and forced heating device (2); E2. After the engineering vehicle is in operation, the engineering vehicle operator sends a preheating and insulation start command to the controller (10). E2. When the temperature detected by the temperature sensor (12) is between (T1, T2], the controller (10) controls the overflow valve (8) to be at the second preset pressure value, controls the directional valve I (7) to be switched to the off position with a delay, and controls the directional valve IV (16) and directional valve V (17) to be in the on position, so as to realize the hydraulic oil delivery to the rotary hydraulic motor (22), the travel hydraulic motor (20), the center rotary joint (115) and the main valve (21).

9. The method of using the hydraulic control system for preheating and heat preservation of the hydraulic system of engineering vehicles as described in claim 8, characterized in that: The preheating phase also includes a heat dissipation phase, with the following specific steps: P1. The engineering vehicle operator sends a preheating and insulation stop command to the controller (10). P2. When the temperature detected by the temperature sensor (12) is greater than T2, the controller (10) controls the reversing valve II (14) to switch the working position and controls the reversing valve I (7) to stay in the open position. At this time, the hydraulic oil drives the fan motor (4) to dissipate heat.

10. An engineering vehicle, characterized in that: The invention includes the hydraulic control system for preheating and heat preservation of the hydraulic system of an engineering vehicle as described in any one of claims 1-7, wherein the engineering vehicle is a hydraulic excavator, and the hydraulic excavator uses the method of the hydraulic control system for preheating and heat preservation of the hydraulic system of the engineering vehicle as described in any one of claims 8-9.

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