An electric control lifting hydraulic system of a mine dump truck

Abstract

The utility model provides a kind of mining dump truck electric control lifting hydraulic system, including hydraulic oil tank, lifting pump, lifting cylinder, ascending electric control valve group and descending electric control valve group, lifting cylinder big cavity oil pipeline and lifting cylinder small cavity oil pipeline between being provided with floating control valve group;Floating control valve group oil outlet is communicated with oil return line;Lifting pump is provided with bypass oil return valve group between oil return line.This utility model replaces original hydraulic control valve group, reduces the layout of a large number of hydraulic control pipeline, simultaneously control speed is faster, reaction is more sensitive;Floating control valve group can provide effective buffer when carriage shakes, avoid rigid contact inside lifting cylinder, further improve the service life of lifting cylinder;Bypass oil return valve group when vehicle is in keeping state, pumped hydraulic oil in the continuous working process of lifting pump returns to hydraulic oil tank by bypass oil return valve group, protect equipment safety, improve the operating stability of hydraulic system.

Description

Technical Field

[0001] This utility model relates to a hydraulic system, specifically an electrically controlled lifting hydraulic system for mining dump trucks. Background Technology

[0002] As a core piece of equipment for open-pit mining transportation, the performance of the lifting hydraulic system of mining dump trucks directly determines loading and unloading efficiency, operational safety, and overall vehicle reliability. Currently, the hydraulically controlled lifting hydraulic system (i.e., a system where the hydraulic pilot controls the hydraulic main valve), which is widely used in the industry, while meeting basic functional requirements to a certain extent, is increasingly showing many inherent defects and limitations in practical applications and future development needs. This has become a key bottleneck restricting the improvement of equipment performance and intelligent upgrades.

[0003] One of the core drawbacks of hydraulic control systems is their slow response speed. Their operation relies on hydraulic oil as both the transmission medium and power source. The hydraulic oil flows through a complex and lengthy pipeline network, exhibiting significant viscous resistance, and the establishment and transmission of pressure waves inevitably involve a time delay. This inherent physical characteristic of the fluid results in a noticeable lag between the issuance of the operating command and the effective action of the actuator (lifting cylinder). Under the demanding conditions of frequent and rapid loading and unloading in mining dump trucks, this delay reduces lifting efficiency, affects the work cycle, and restricts production efficiency and the user experience. The control accuracy of the hydraulic lifting system is significantly affected by factors such as the machining accuracy of the pilot valve core, the viscosity of the system oil, and the internal leakage of the pilot valve; this limits control accuracy and makes stability susceptible to interference. To achieve remote control of the main valve by the pilot valve, a large number of complex hydraulic lines need to be laid out between the cab, pilot valve, main valve, and actuator. This not only increases system weight and occupies valuable space but also makes the overall hydraulic pipeline layout intricate, messy, and unsightly, increasing the difficulty and cost of design, manufacturing, and assembly. Summary of the Invention

[0004] Purpose of the invention: To address the shortcomings of existing technologies, this utility model provides an electrically controlled lifting hydraulic system for mining dump trucks, thereby solving the problems mentioned in the background section.

[0005] Technical solution: A hydraulic system for lifting a mining dump truck with electric control, including a hydraulic oil tank, a lifting pump, a lifting cylinder, an electric control valve group for raising the lifting cylinder and the lifting pump, and an electric control valve group for lowering the lifting cylinder and the lifting pump, wherein the electric control valve group for raising the lifting cylinder and the electric control valve group for lowering the lifting pump are arranged on two different oil lines. A floating control valve assembly is installed between the large chamber oil supply pipeline and the small chamber oil supply pipeline of the lifting cylinder; the oil outlet of the floating control valve assembly is connected to the return oil pipeline. A bypass return oil valve assembly is installed between the lifting pump and the return oil pipeline.

[0006] This invention replaces the original hydraulic control valve assembly with a lifting solenoid valve assembly, a lowering solenoid valve assembly, a floating control valve assembly, and a bypass return valve assembly, reducing the amount of hydraulic pipeline layout and providing faster control and more sensitive response. The floating control valve assembly provides effective buffering when the vehicle body shakes due to changes in load center of gravity or road conditions during vehicle operation, avoiding hard contact inside the lifting cylinder and further extending the service life of the lifting cylinder. When the vehicle is in a held-down state, the hydraulic oil pumped out by the lifting pump during continuous operation returns to the hydraulic oil tank through the bypass return valve assembly, preventing damage to the lifting pump, protecting equipment safety, and improving the operational stability of the hydraulic system.

[0007] The rising solenoid valve assembly includes a rising cartridge valve, a rising pilot solenoid valve, and a first shuttle valve for controlling the rising cartridge valve; the first shuttle valve is located on the control oil line between the oil inlet line of the rising cartridge valve and the rising pilot solenoid valve, and the rising pilot solenoid valve is located on the control oil line between the spring chamber of the rising cartridge valve and the control return line. The spring chamber of the rising cartridge valve is connected to the return oil line of the rising pilot solenoid valve. When the rising pilot solenoid valve is energized, the oil in the spring chamber of the rising cartridge valve flows back to the hydraulic oil tank through the control return oil line.

[0008] During the lifting operation, the lifting pilot solenoid valve is energized, and the hydraulic oil pumped by the lifting pump is delivered to the lower chamber of the lifting cartridge valve through the hydraulic pipeline. During this process, the pipeline transmits the oil signal to the first shuttle valve through the control oil line. The valve core of the first shuttle valve switches, controlling the flow of oil through the lifting pilot solenoid valve. Since the oil inlet is blocked at the spring chamber of the lifting cartridge valve at this time, the oil does not enter the spring chamber. The hydraulic oil in the lower chamber continuously accumulates and pushes up the valve core of the lifting cartridge valve. The spring in the spring chamber is compressed, and the oil flows back to the hydraulic oil tank through the control oil line between the spring chamber and the return oil line. The hydraulic oil in the main oil line is output to the large chamber of the lifting cylinder through the side chamber of the lifting cartridge valve, realizing the lifting action.

[0009] The descent electronically controlled valve assembly includes a descent cartridge valve, a descent pilot solenoid valve, and a second shuttle valve for controlling the descent cartridge valve; the second shuttle valve is located on the control oil line between the oil inlet line of the descent cartridge valve and the descent pilot solenoid valve, and the descent pilot solenoid valve is located on the control oil line between the spring chamber of the descent cartridge valve and the control return line. The spring chamber of the descending cartridge valve is connected to the return oil line of the descending pilot solenoid valve. When the descending pilot solenoid valve is energized, the oil in the spring chamber of the descending cartridge valve flows back to the hydraulic oil tank through the control return oil line.

[0010] During the descent operation, the descent pilot solenoid valve is energized, and the hydraulic oil pumped by the lifting pump is delivered to the lower chamber of the descent cartridge valve through the hydraulic pipeline. During this process, the pipeline outputs the oil signal to the second shuttle valve through the control oil line. The valve core of the second shuttle valve switches, controlling the flow of oil through the descent pilot solenoid valve. Since the oil inlet is blocked at the spring chamber of the descent cartridge valve at this time, the oil does not enter the spring chamber. The hydraulic oil in the lower chamber continuously accumulates and pushes up the valve core of the descent cartridge valve. The spring in the spring chamber is compressed, and the oil flows back to the hydraulic oil tank through the control oil line between the spring chamber and the return oil line. The hydraulic oil in the main oil line is output to the small chamber of the lifting cylinder through the side chamber of the descent cartridge valve, realizing the descent action.

[0011] The floating control valve assembly includes a first floating cartridge valve and a second floating cartridge valve whose side chambers are interconnected. The side chamber of the first floating cartridge valve is connected to the side chamber of the rising cartridge valve via a hydraulic line, and the side chamber of the second floating cartridge valve is connected to the side chamber of the falling cartridge valve via a hydraulic line. A first pilot solenoid valve and a second pilot solenoid valve are provided in the oil circuit between the first floating cartridge valve and the second floating cartridge valve. The oil circuit between the first pilot solenoid valve and the second pilot solenoid valve is connected to the return oil line. The lower chambers of the first floating cartridge valve and the second floating cartridge valve are connected to the return oil line. A third pilot solenoid valve and a first relief valve are installed on the hydraulic line between the lowering solenoid valve assembly and the second floating cartridge valve. The third pilot solenoid valve is installed on the oil line between the lowering solenoid valve assembly and the lifting cylinder chamber, and when power is lost, only the oil line between the lowering solenoid valve assembly and the lifting cylinder chamber is connected. The first relief valve is installed on the oil line between the lifting cylinder chamber and the second floating cartridge valve.

[0012] In floating operation, the first pilot solenoid valve, the second pilot solenoid valve, and the third pilot solenoid valve are energized. The oil passage between the large and small chambers of the lifting cylinder is connected through the side chambers of the first and second floating cartridge valves. When the vehicle body shakes, the hydraulic oil in the two chambers flows flexibly under the action of the floating control valve group, avoiding the problem of sudden changes in cylinder pressure caused by shaking affecting the service life of the lifting cylinder.

[0013] The bypass return valve assembly includes a return cartridge valve and a fourth pilot solenoid valve and a second relief valve for controlling the return cartridge valve. The return cartridge valve has a throttling orifice that passes through the valve core. The throttling orifice is connected to the control oil circuit of the fourth pilot solenoid valve and the second relief valve to increase the pressure of the control oil. When the fourth pilot solenoid valve is energized, the high-pressure oil flows back to the hydraulic oil tank through the second relief valve.

[0014] The bypass return valve assembly operates when the vehicle is in hold mode. During hold mode, the lift pump continues to work. To prevent the continuous increase in system pressure from affecting the hydraulic system and to protect the healthy operation of the lift pump, the fourth pilot solenoid valve is energized, blocking the oil circuit. The hydraulic oil entering the return cartridge valve is continuously pressurized through the throttle orifice to control the oil pressure until the oil pressure reaches the opening pressure of the second relief valve. The hydraulic oil in the spring chamber flows back to the hydraulic oil tank through the second relief valve. The return cartridge valve core actuates, and the hydraulic oil in the main oil circuit flows back to the hydraulic oil tank through the side chamber of the return cartridge valve.

[0015] An inlet filter is installed on the hydraulic pipeline connected to the oil outlet of the lifting pump.

[0016] Installing an inlet filter on the inlet line can effectively filter impurities, keeping the hydraulic oil entering the working valve clean and not affecting the normal operation of the working valve.

[0017] An oil return filter is installed on the oil return pipeline.

[0018] A return oil filter is installed to filter the oil again when it flows back to the hydraulic oil tank after being used by the working valve. This filters out impurities generated in the hydraulic system and prevents them from entering the hydraulic oil tank and affecting the next cycle.

[0019] It also includes a merging pipeline connected to the steering hydraulic system, the merging pipeline being connected to the pipeline between the lifting pump and the lifting solenoid valve group and the lowering solenoid valve group, and a fifth pilot solenoid valve being installed on the merging pipeline; when the fifth pilot solenoid valve is energized, the merging pipeline is in an unobstructed state.

[0020] Combining the hydraulic oil from the steering hydraulic system with that from the lifting hydraulic system can effectively reduce the displacement of the lifting pump and lower costs.

[0021] A lifting pressure sensor is installed on the oil inlet pipe of the large chamber of the lifting cylinder, and a descent pressure sensor is installed on the oil inlet pipe of the small chamber of the lifting cylinder.

[0022] To achieve automatic control, lifting pressure sensors and lowering pressure sensors are installed. By monitoring the oil pressure in the large and small chambers, the control mode is adjusted in real time to improve driving comfort.

[0023] Beneficial Effects: This utility model replaces the original hydraulic control valve group with a lifting solenoid valve group, a lowering solenoid valve group, a floating control valve group, and a bypass return valve group, reducing the layout of a large number of hydraulic control pipelines. It also offers faster control speed and more sensitive response. The floating control valve group provides effective buffering when the vehicle body shakes due to changes in load center of gravity or road conditions during vehicle operation, avoiding hard contact inside the lifting cylinder and further extending the service life of the lifting cylinder. When the vehicle is in a held-down state, the hydraulic oil pumped out by the lifting pump during continuous operation returns to the hydraulic oil tank through the bypass return valve group, preventing damage to the lifting pump, protecting equipment safety, and improving the operational stability of the hydraulic system. Compared to the hydraulic spool valve structure, the control accuracy is low due to internal leakage of the valve core. Using a cartridge-type solenoid valve results in less internal leakage and higher control accuracy. Furthermore, the electro-hydraulic lifting system makes it easier to achieve intelligent control of the entire machine, facilitating subsequent development of a drive-by-wire system. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0025] Figure 1 This is the overall hydraulic principle diagram of this utility model.

[0026] Figure 2 This is a hydraulic schematic diagram of the lifting solenoid valve assembly of this utility model.

[0027] Figure 3 This is a hydraulic schematic diagram of the lowering electrically controlled valve assembly of this utility model.

[0028] Figure 4 This is a hydraulic schematic diagram of the floating control valve group of this utility model.

[0029] Figure 5 This is a hydraulic schematic diagram of the bypass return valve assembly of this utility model. Detailed Implementation

[0030] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0031] In the description of this utility model, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "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 utility model 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 limitations on this utility model.

[0032] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0033] Example 1, such as Figure 1 As shown, an electrically controlled lifting hydraulic system for a mining dump truck includes a hydraulic oil tank 1, a lifting pump 2, a lifting cylinder 3, an upward electrically controlled valve group 4 disposed on the oil line between the large chamber of the lifting cylinder 3 and the lifting pump 2, and a downward electrically controlled valve group 5 disposed between the small chamber of the lifting cylinder 3 and the lifting pump 2. The upward electrically controlled valve group 4 and the downward electrically controlled valve group 5 are disposed on two different oil lines. A floating control valve assembly 6 is provided between the oil supply pipeline of the large chamber of the lifting cylinder 3 and the oil supply pipeline of the small chamber of the lifting cylinder 3; the oil outlet of the floating control valve assembly 6 is connected to the return oil pipeline. A bypass return oil valve assembly 7 is provided between the lifting pump 2 and the return oil pipeline.

[0034] This invention replaces the original hydraulic control valve assembly with an upward solenoid valve assembly 4, a downward solenoid valve assembly 5, a floating control valve assembly 6, and a bypass return valve assembly 7, reducing the layout of a large number of hydraulic control pipelines. It also provides faster control speed and more sensitive response. The floating control valve assembly 6 provides effective buffering when the vehicle body shakes due to changes in load center of gravity or road conditions during vehicle operation, preventing hard contact inside the lifting cylinder 3 and further extending the service life of the lifting cylinder 3. When the vehicle is in a held-down state, the hydraulic oil pumped out by the lifting pump 2 during continuous operation returns to the hydraulic oil tank 1 through the bypass return valve assembly 7, preventing damage to the lifting pump 2, protecting equipment safety, and improving the operational stability of the hydraulic system.

[0035] Example 2, as follows Figure 2 As shown, the rising solenoid valve group 4 includes a rising cartridge valve 41 and a rising pilot solenoid valve 42 and a first shuttle valve 43 for controlling the rising cartridge valve 41; the first shuttle valve 43 is disposed on the control oil line between the oil inlet line of the rising cartridge valve 41 and the rising pilot solenoid valve 42, and the rising pilot solenoid valve 42 is disposed on the control oil line between the spring chamber of the rising cartridge valve 41 and the control return line. The spring chamber of the rising cartridge valve 41 is connected to the return oil line of the rising pilot solenoid valve 42. When the rising pilot solenoid valve 42 is energized, the oil in the spring chamber of the rising cartridge valve 41 flows back to the hydraulic oil tank 1 through the control return oil line.

[0036] During the lifting operation, the lifting pilot solenoid valve 42 is energized, and the hydraulic oil pumped by the lifting pump 2 is delivered to the lower chamber of the lifting cartridge valve 41 through the hydraulic pipeline. During the process, the pipeline outputs the oil signal to the first shuttle valve 43 through the control oil pipe. The valve core of the first shuttle valve 43 switches, controlling the flow of oil through the lifting pilot solenoid valve 42. Since the oil inlet is blocked at the spring chamber of the lifting cartridge valve 41 at this time, the oil does not enter the spring chamber. The hydraulic oil in the lower chamber continuously accumulates and pushes up the valve core of the lifting cartridge valve 41. The spring in the spring chamber is compressed, and the oil flows back to the hydraulic oil tank 1 through the control oil circuit between the spring chamber and the return oil pipeline. The hydraulic oil in the main oil circuit is output to the main chamber of the lifting cylinder 3 through the side chamber of the lifting cartridge valve 41, realizing the lifting action.

[0037] Example 3, such as Figure 3 As shown, the descent electronically controlled valve assembly 5 includes a descent cartridge valve 51 and a descent pilot solenoid valve 52 and a second shuttle valve 53 for controlling the descent cartridge valve 51; the second shuttle valve 53 is disposed on the control oil line between the oil inlet line of the descent cartridge valve 51 and the descent pilot solenoid valve 52, and the descent pilot solenoid valve 52 is disposed on the control oil line between the spring chamber of the descent cartridge valve 51 and the control return line; The spring chamber of the descending cartridge valve 51 is connected to the return oil line of the descending pilot solenoid valve 52. When the descending pilot solenoid valve 52 is energized, the oil in the spring chamber of the descending cartridge valve 51 flows back to the hydraulic oil tank 1 through the control return oil line.

[0038] During the descent operation, the descent pilot solenoid valve 52 is energized, and the hydraulic oil pumped by the lifting pump 2 is delivered to the lower chamber of the descent cartridge valve 51 through the hydraulic pipeline. During this process, the pipeline outputs the oil signal to the second shuttle valve 53 through the control oil pipe. The valve core of the second shuttle valve 53 switches, controlling the flow of oil through the descent pilot solenoid valve 52. Since the oil inlet is blocked at the spring chamber of the descent cartridge valve 51 at this time, the oil does not enter the spring chamber. The hydraulic oil in the lower chamber continuously accumulates and pushes up the valve core of the descent cartridge valve 51. The spring in the spring chamber is compressed, and the oil flows back to the hydraulic oil tank 1 through the control oil circuit between the spring chamber and the return oil pipeline. The hydraulic oil in the main oil circuit is output to the small chamber of the lifting cylinder 3 through the side chamber of the descent cartridge valve 51, realizing the descent action.

[0039] Example 4, such as Figure 4 As shown, the floating control valve group 6 includes a first floating cartridge valve 61 and a second floating cartridge valve 62 whose side chambers are interconnected. The side chamber of the first floating cartridge valve 61 is connected to the side chamber of the rising cartridge valve 41 through a hydraulic line, and the side chamber of the second floating cartridge valve 62 is connected to the side chamber of the falling cartridge valve 51 through a hydraulic line. A first pilot solenoid valve 63 and a second pilot solenoid valve 64 are provided in the oil circuit between the first floating cartridge valve 61 and the second floating cartridge valve 62. The oil circuit between the first pilot solenoid valve 63 and the second pilot solenoid valve 64 is connected to the return oil line. The lower chambers of the first floating cartridge valve 61 and the second floating cartridge valve 62 are connected to the return oil line. A third pilot solenoid valve 65 and a first relief valve 66 are provided on the hydraulic line between the lowering solenoid valve group 5 and the second floating cartridge valve 62. The third pilot solenoid valve 65 is located on the oil line between the lowering solenoid valve group 5 and the small chamber of the lifting cylinder 3. When power is lost, only the oil line between the lowering solenoid valve group 5 and the small chamber of the lifting cylinder 3 is connected. The first relief valve 66 is located on the oil line between the small chamber of the lifting cylinder 3 and the second floating cartridge valve 62.

[0040] In this embodiment, both the first floating cartridge valve and the second floating cartridge valve are adjustable back pressure type, which controls the lifting pressure of the spring cavity according to the working requirements to adapt to more working needs.

[0041] During floating operation, the first pilot solenoid valve 63, the second pilot solenoid valve 64, and the third pilot solenoid valve 65 are energized. The oil passage between the large and small chambers of the lifting cylinder 3 is connected through the side chambers of the first floating cartridge valve 61 and the second floating cartridge valve 62. When the vehicle body shakes, the hydraulic oil in the two side chambers flows flexibly under the action of the floating control valve group 6, avoiding the problem of sudden changes in cylinder pressure caused by shaking affecting the service life of the lifting cylinder 3.

[0042] Example 5, as follows Figure 5As shown, the bypass return valve assembly 7 includes a return cartridge valve 71 and a fourth pilot solenoid valve 72 and a second relief valve 73 for controlling the return cartridge valve 71. The valve core of the return cartridge valve 71 is provided with a throttling orifice that passes through the valve core. The throttling orifice is connected to the control oil circuit of the fourth pilot solenoid valve 72 and the second relief valve 73 to increase the pressure of the control oil. When the fourth pilot solenoid valve 72 is energized, the high-pressure oil flows back to the hydraulic oil tank 1 through the second relief valve 73.

[0043] The bypass return valve assembly 7 operates when the vehicle is in the holding condition. During the holding condition, the lift pump 2 continues to work. To prevent the continuous increase in system pressure from affecting the hydraulic system and to protect the healthy operation of the lift pump 2, the fourth pilot solenoid valve 72 is energized, which blocks the oil circuit. The hydraulic oil entering the return cartridge valve 71 is continuously pressurized through the throttle orifice to control the oil pressure until the oil pressure reaches the opening pressure of the second relief valve 73. The hydraulic oil in the spring chamber flows back to the hydraulic oil tank 1 through the second relief valve 73. The valve core of the return cartridge valve is activated, and the hydraulic oil in the main oil circuit flows back to the hydraulic oil tank 1 through the side chamber of the return cartridge valve.

[0044] An oil inlet filter 8 is installed on the hydraulic pipeline connected to the oil outlet of the lifting pump 2.

[0045] Installing an inlet filter 8 on the inlet pipeline can effectively filter impurities, keeping the hydraulic oil entering the working valve clean and not affecting the normal operation of the working valve.

[0046] A return oil filter 9 is installed on the return oil pipeline.

[0047] A return oil filter 9 is installed to filter the oil again when it flows back to the hydraulic oil tank 1 after the working valve has been used. This filters out impurities generated in the hydraulic system and prevents them from entering the hydraulic oil tank 1 and affecting the next cycle.

[0048] It also includes a merging pipeline connected to the steering hydraulic system. The merging pipeline is connected to the pipeline between the lifting pump 2 and the rising solenoid valve group 4 and the lowering solenoid valve group 5. A fifth pilot solenoid valve 10 is provided on the merging pipeline. When the fifth pilot solenoid valve 10 is energized, the merging pipeline is in an unobstructed state.

[0049] By combining the hydraulic oil from the steering hydraulic system with that from the lifting hydraulic system, the displacement of the lifting pump 2 can be effectively reduced, thus lowering costs.

[0050] A lifting pressure sensor 11 is installed on the oil inlet pipe of the large chamber of the lifting cylinder 3, and a descent pressure sensor 12 is installed on the oil inlet pipe of the small chamber of the lifting cylinder 3.

[0051] To achieve automatic control, a lifting pressure sensor 11 and a lowering pressure sensor 12 are installed. The control mode is adjusted in real time by monitoring the oil pressure in the large and small chambers to improve driving comfort.

[0052] When in lifting mode, if the pressure detected by the lifting pressure sensor 117 is greater than the system set pressure value, it will automatically control and cut off the electrical signals of the lifting pilot solenoid valve 42, the second pilot solenoid valve 64, the fourth pilot solenoid valve 72, and the fifth pilot solenoid valve 10, and automatically switch the lifting status signal to the holding status signal.

[0053] When in descent mode, if the pressure detected by the descent pressure sensor 125 is greater than the system set pressure value, it will automatically control the shut-off of the descent pilot solenoid valve 52 and the fourth pilot solenoid valve 72, and simultaneously control the second pilot solenoid valve 64 and the third pilot solenoid valve 65 to be energized, automatically switching the power descent state signal to the floating state signal.

[0054] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.

[0055] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A hydraulically controlled lifting system for a mining dump truck, characterized in that: It includes a hydraulic oil tank (1), a lifting pump (2), a lifting cylinder (3), an upward solenoid valve group (4) set on the oil line between the large chamber of the lifting cylinder (3) and the lifting pump (2), and a downward solenoid valve group (5) set on the small chamber of the lifting cylinder (3) and the lifting pump (2). The upward solenoid valve group (4) and the downward solenoid valve group (5) are set on two different oil lines. A floating control valve assembly (6) is provided between the large chamber oil supply pipeline of the lifting cylinder (3) and the small chamber oil supply pipeline of the lifting cylinder (3); the oil outlet of the floating control valve assembly (6) is connected to the return oil pipeline; A bypass return oil valve assembly (7) is provided between the lifting pump (2) and the return oil pipeline.

2. The electro-hydraulic lifting system for mining dump trucks according to claim 1, characterized in that: The rising solenoid valve assembly (4) includes a rising cartridge valve (41) and a rising pilot solenoid valve (42) and a first shuttle valve (43) for controlling the rising cartridge valve (41); the first shuttle valve (43) is disposed on the control oil line between the oil inlet line of the rising cartridge valve (41) and the rising pilot solenoid valve (42), and the rising pilot solenoid valve (42) is disposed on the control oil line between the spring chamber of the rising cartridge valve (41) and the control return line; The spring chamber of the rising cartridge valve (41) is connected to the return oil line of the rising pilot solenoid valve (42). When the rising pilot solenoid valve (42) is energized, the oil in the spring chamber of the rising cartridge valve (41) flows back to the hydraulic oil tank (1) through the control return oil line.

3. The electro-hydraulic lifting system for mining dump trucks according to claim 2, characterized in that: The descent control valve assembly (5) includes a descent cartridge valve (51), a descent pilot solenoid valve (52) for controlling the descent cartridge valve (51), and a second shuttle valve (53); the second shuttle valve (53) is disposed on the control oil line between the oil inlet line of the descent cartridge valve (51) and the descent pilot solenoid valve (52), and the descent pilot solenoid valve (52) is disposed on the control oil line between the spring chamber of the descent cartridge valve (51) and the control return line; The spring chamber of the descending cartridge valve (51) is connected to the return oil line of the descending pilot solenoid valve (52). When the descending pilot solenoid valve (52) is energized, the oil in the spring chamber of the descending cartridge valve (51) flows back to the hydraulic oil tank (1) through the control return oil line.

4. The electro-hydraulic lifting system for mining dump trucks according to claim 3, characterized in that: The floating control valve group (6) includes a first floating cartridge valve (61) and a second floating cartridge valve (62) whose side chambers are interconnected. The side chamber of the first floating cartridge valve (61) is connected to the side chamber of the rising cartridge valve (41) through a hydraulic line, and the side chamber of the second floating cartridge valve (62) is connected to the side chamber of the falling cartridge valve (51) through a hydraulic line. A first pilot solenoid valve (63) and a second pilot solenoid valve (64) are provided in the oil circuit between the first floating cartridge valve (61) and the second floating cartridge valve (62). The oil circuit between the first pilot solenoid valve (63) and the second pilot solenoid valve (64) is connected to the return oil line. The lower chamber of the first floating cartridge valve (61) and the lower chamber of the second floating cartridge valve (62) are connected to the return oil line. A third pilot solenoid valve (65) and a first relief valve (66) are provided on the hydraulic line between the lowering solenoid valve group (5) and the second floating cartridge valve (62). The third pilot solenoid valve (65) is provided on the oil line between the lowering solenoid valve group (5) and the small chamber of the lifting cylinder (3). When the power is lost, only the oil line between the lowering solenoid valve group (5) and the small chamber of the lifting cylinder (3) is connected. The first relief valve (66) is provided on the oil line between the small chamber of the lifting cylinder (3) and the second floating cartridge valve (62).

5. The electro-hydraulic lifting system for mining dump trucks according to claim 1, characterized in that: The bypass return valve assembly (7) includes a return cartridge valve (71) and a fourth pilot solenoid valve (72) and a second relief valve (73) for controlling the return cartridge valve (71). The valve core of the return cartridge valve (71) is provided with a throttle hole that passes through the valve core. The throttle hole is connected to the control oil circuit of the fourth pilot solenoid valve (72) and the second relief valve (73) to increase the pressure of the control oil. When the fourth pilot solenoid valve (72) is energized, the high-pressure oil flows back to the hydraulic oil tank (1) through the second relief valve (73).

6. The electro-hydraulic lifting system for mining dump trucks according to claim 1, characterized in that: An oil inlet filter (8) is installed on the hydraulic pipeline connected to the oil outlet of the lifting pump (2).

7. The electro-hydraulic lifting system for mining dump trucks according to claim 1, characterized in that: A return oil filter (9) is installed on the return oil pipeline.

8. The electro-hydraulic lifting system for mining dump trucks according to claim 1, characterized in that: It also includes a merging pipeline connected to the steering hydraulic system, the merging pipeline being connected to the pipeline between the lifting pump (2) and the rising solenoid valve group (4) and the falling solenoid valve group (5), and a fifth pilot solenoid valve (10) is provided on the merging pipeline; when the fifth pilot solenoid valve (10) is energized, the merging pipeline is in a smooth state.

9. The electro-hydraulic lifting system for mining dump trucks according to claim 1, characterized in that: A lifting pressure sensor (11) is installed on the oil inlet pipe of the large cavity of the lifting cylinder (3), and a descent pressure sensor (12) is installed on the oil inlet pipe of the small cavity of the lifting cylinder (3).

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