Variable displacement concrete pump hydraulic system for coal mine and pumping equipment

Abstract

The utility model discloses a variable displacement concrete pump hydraulic system and pumping equipment for a coal mine, and belongs to the field of hydraulic systems of underground coal mine concrete equipment. The system comprises a hydraulic oil tank, an outlet of the hydraulic oil tank is connected with a first working port of a variable hydraulic pump, the variable hydraulic pump is connected with a motor, a second working port of the variable hydraulic pump is connected with an energy accumulator, and a third working port of the variable hydraulic pump is connected with an oil inlet of a forward and reverse pump manual operation valve. An oil return opening of the positive and negative pump manual operation valve is connected with an inlet of an oil return way, an outlet of the oil return way is connected with an inlet of the hydraulic oil tank, a fourth working opening of the variable hydraulic pump is connected with a first working opening of a pressure reducing valve, and a fifth working opening of the variable hydraulic pump is connected with a first working opening of a main overflow valve. A second working opening of the main overflow valve is connected with the oil return way, a third working opening of the main overflow valve is connected with a second working opening of the pressure reducing valve, and the forward and reverse pump manual operation valve is connected with a swing oil cylinder assembly and a pumping oil cylinder assembly. According to the hydraulic system, the effect of changing the concrete pumping amount can be achieved by adjusting the output pressure of the hydraulic valve, and the adaptability of a single concrete pump to different working conditions is enhanced.

Description

Technical Field

[0001] The utility model belongs to the field of hydraulic systems of underground concrete equipment in coal mines, and relates to a hydraulic system of a variable displacement concrete pump for coal mines and pumping equipment. Background Art

[0002] Shotcrete is an important technical method for surrounding rock support. It can be categorized into three types: dry, damp, and wet shotcrete, depending on the amount of water added and the point at which it is added. Dry shotcrete is not suitable for use underground in coal mines due to its high dust concentration and high rebound. Tidal shotcrete also has poor dust and rebound control. In comparison, the wet process, which involves preparing finished concrete before shotcreting, offers the inherent advantages of being dust-free, having low rebound, and having high strength. However, the limited space underground and the discontinuous nature of material transportation present key challenges in promoting the use of wet shotcrete in coal mines.

[0003] Because some coal mines have narrow underground tunnels that cannot meet the traffic conditions of concrete mixer trucks, the process mode of pre-mixing dry materials on the well and adding water and accelerators underground is adopted. However, due to the complexity of the underground environment, it is impossible to ensure sufficient supply of dry materials for the concrete spraying unit. To solve this problem, it is necessary to adjust the concrete spraying volume. That is, when the dry material supply is insufficient, the pumping volume of the concrete pump is reduced, and the efficiency of the concrete pump spraying is reduced to meet the transportation requirements. In addition, when there is an interval between two pumpings of the concrete pump, the pumping pipeline needs to be cleaned. In order to reduce the frequency of pipeline cleaning and reduce the labor intensity of the staff, this can be achieved by extending the pumping time and reducing the pumping interval.

[0004] In order to solve the above problems, the prior art provides a Figure 1 The variable-displacement concrete pump hydraulic system shown in the figure uses a fixed-displacement hydraulic pump. In a hydraulic system using a fixed-displacement hydraulic pump, if an abnormality such as a pipe blockage occurs, the system pressure will rise sharply. Because the fixed-displacement pump cannot automatically adjust the output flow to reduce pressure, this can cause system overload and even damage the motor or hydraulic pump. Furthermore, because the fixed-displacement hydraulic pump cannot adjust according to actual needs, if the working conditions change during the concrete pumping process (such as pipe blockage, changes in concrete consistency, etc.), the pumping volume cannot be adjusted in time, resulting in reduced work efficiency or equipment damage. Utility Model Content

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a variable-displacement concrete pump hydraulic system and pumping equipment for coal mines, which can achieve the effect of changing the concrete pumping volume by adjusting the output pressure of the hydraulic valve, thereby enhancing the adaptability of a single concrete pump to different working conditions, enhancing the versatility and interchangeability of the concrete pump, and reducing the number of spare parts.

[0006] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0007] The utility model provides a variable displacement concrete pump hydraulic system for coal mines, comprising a hydraulic oil tank, an outlet of the hydraulic oil tank being connected to a first working port of a variable hydraulic pump, the variable hydraulic pump being connected to a motor, a second working port of the variable hydraulic pump being connected to an accumulator, a third working port of the variable hydraulic pump being connected to an oil inlet of a manual operating valve of a forward and reverse pump, an oil return port of the manual operating valve of the forward and reverse pump being connected to an inlet of an oil return circuit, an outlet of the oil return circuit being connected to the inlet of the hydraulic oil tank, a fourth working port of the variable hydraulic pump being connected to a first working port of a pressure reducing valve, a fifth working port of the variable hydraulic pump being connected to a first working port of a main overflow valve, a second working port of the main overflow valve being connected to the oil return circuit, a third working port of the main overflow valve being connected to a second working port of the pressure reducing valve, and the manual operating valve of the forward and reverse pump being connected to a swing cylinder assembly and a pumping cylinder assembly.

[0008] In one embodiment, the pumping cylinder assembly includes a first pumping cylinder and a second pumping cylinder, and the first pumping cylinder and the second pumping cylinder are connected.

[0009] In one embodiment, the swing cylinder assembly includes a swing cylinder 1 and a swing cylinder 2, and the piston rod chambers of the swing cylinder 1 and the swing cylinder 2 are connected in series.

[0010] In one embodiment, an oil suction filter is provided between the hydraulic oil tank and the variable hydraulic pump.

[0011] In one embodiment, a radiator and an oil return filter are sequentially arranged on the oil return line.

[0012] In one embodiment, the forward and reverse pump manual operation valve is an M-type center-position reversing valve.

[0013] In one embodiment, in the standby state, the pressure reducing valve is in the minimum state, the hydraulic oil in the hydraulic oil tank is pressurized by the variable hydraulic pump, a part of it enters the accumulator, the forward and reverse pump manual operation valve is in the neutral functional state, and the other part directly returns to the oil return port through the oil inlet of the forward and reverse pump manual operation valve, and returns to the hydraulic oil tank through the return oil line.

[0014] In one embodiment, during the forward pumping operation, the forward and reverse pump manual operating valve is in the a-function working state, the pressure of the pressure reducing valve is adjusted to the flow rate required by the hydraulic system, part of the high-pressure oil enters the accumulator, and the remaining high-pressure oil passes through the forward and reverse pump manual operating valve and enters the pumping cylinder assembly and the swing cylinder assembly to complete a forward pumping cycle;

[0015] During reverse pumping, the manual operating valve of the forward and reverse pumps is in the b functional working state opposite to the a functional working state. The pressure of the pressure reducing valve is adjusted to the flow rate required by the hydraulic system. Part of the high-pressure oil enters the accumulator, and the remaining high-pressure oil passes through the manual operating valve of the forward and reverse pumps and enters the pumping cylinder assembly and the swing cylinder assembly to complete a reverse pumping cycle.

[0016] In one embodiment, the variable hydraulic pump has a model number of TBP63S-100R-2N*.

[0017] The utility model provides a pumping device, comprising the variable displacement concrete pump hydraulic system for coal mines.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The utility model provides a variable displacement concrete pump hydraulic system for coal mines. The system is equipped with a variable displacement hydraulic pump. The fixed displacement hydraulic pump in the improved hydraulic system is replaced with a variable displacement hydraulic pump with total power control and positive flow control. The total power control of the variable displacement hydraulic pump ensures that, by controlling the maximum output power of the hydraulic system, when an abnormality such as pipe blockage occurs during concrete pumping, the system pressure increases. At this time, the constant power system begins to operate, reducing the hydraulic system flow rate. This ensures that the total power required by the hydraulic system remains constant during system operation, protecting the motor from motor stalling and damage due to excessive power required by the hydraulic system. Furthermore, a pressure reducing valve is added between the variable displacement hydraulic pump outlet and the pump pilot control port. The pressure reducing valve reduces the variable displacement hydraulic pump outlet pressure to a specified pressure Pi. As the control pressure Pi increases, the pump output flow rate increases. The utility model can achieve the effect of varying the concrete pumping volume by adjusting the output pressure of the hydraulic valve, thereby enhancing the adaptability of a single concrete pump to different working conditions, increasing the versatility and interchangeability of the concrete pump, and reducing the number of spare parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of a hydraulic system of a variable displacement concrete pump for coal mines in the prior art;

[0021] Figure 2 This is a schematic diagram of the hydraulic system of a variable displacement concrete pump for coal mines provided by the utility model;

[0022] Figure 3 This is a characteristic curve diagram of the variable hydraulic pump of the utility model;

[0023] Figure 4 This is a diagram showing the relationship between the control pressure Pi and the pump output flow of the variable hydraulic pump of the present invention;

[0024] Figure 5Schematic diagram of the hydraulic principle of the concrete wet spraying machine, where Figures (a-d) respectively show the pumping state of cylinder ①, the suction state of cylinder ②, the left swing state of the distribution valve, the stop state of cylinder ① and cylinder ②, the suction state of cylinder ①, the pumping state of cylinder ②, the right swing state of the distribution valve, and the stop state of cylinder ① and cylinder ②;

[0025] Figure 6 The middle figures (a to c) are schematic diagrams of the pumping cylinder 1, pumping cylinder 2, swing cylinder 1 and swing cylinder 2 in the hydraulic system of the variable displacement concrete pump for coal mines provided by the present invention.

[0026] Among them: 1- hydraulic oil tank; 2- oil suction filter; 3- motor; 4- fixed hydraulic pump; 5- main overflow valve; 6- forward and reverse pump manual operation valve; 7- pumping pilot control valve; 8- pumping cylinder 1; 9- pumping cylinder 2; 10- swing cylinder 1; 11- swing cylinder 2; 12- swing cylinder pilot control valve; 13- radiator; 14- return oil filter; 15- pressure reducing valve; 16- accumulator; 17- variable hydraulic pump; 8.1- pumping cylinder 1; Oil port 1; 8.2- pumping cylinder 1 second oil port; 8.3- pumping cylinder 1 cartridge valve; 8.4- pumping cylinder 1 third oil port; 8.5- pumping cylinder 1 fourth oil port; 9.1- pumping cylinder 2 first oil port; 9.2- pumping cylinder 2 first oil port; 9.3- pumping cylinder 2 cartridge valve; 9.4- pumping cylinder 2 third oil port; 9.5- pumping cylinder 2 fourth oil port; 10.1- first pilot oil port; 11.1- second pilot oil port. DETAILED DESCRIPTION

[0027] In order to help those skilled in the art better understand the present invention, the following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0028] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0029] The present invention is described in further detail below with reference to the accompanying drawings:

[0030] The mechanical structure of the concrete pump is mainly composed of the main oil cylinder, water washing tank, delivery cylinder, swing cylinder, distribution valve, hopper, etc.

[0031] The concrete wet spraying machine pump usually consists of a main oil cylinder, a water washing tank, a delivery cylinder, a swing cylinder, a distribution valve and a hopper. When the wet spraying machine is working, the two main oil cylinders drive the pistons in the two concrete cylinders to push forward or retract alternately, realizing the process of pumping concrete into the delivery pipe. First, the distribution valve feed port is located on the left. The piston pushes forward to complete the concrete cylinder pumping, and the piston retracts to complete the concrete cylinder filling. Figure 5 As shown in (a, b); then the two pistons stop, the distribution valve swings to the right until the feed port contacts the concrete cylinder, and the concrete pumping stops at this time. Figure 5 As shown in (c, d); next, the piston pushes forward, the concrete cylinder pumps material, and the piston retracts to achieve the concrete cylinder filling.

[0032] like Figure 1 The conventional variable-displacement concrete pump hydraulic system for coal mines is shown in the figure. In the standby mode, motor 3 starts, driving fixed-displacement hydraulic pump 4 to rotate. Hydraulic oil in hydraulic tank 1 is filtered through suction filter 2, pressurized by fixed-displacement hydraulic pump 4, and then returned to hydraulic tank 1 through manual valve 6 for forward and reverse pumps, radiator 13, and return filter 14. At this point, manual valve 6 for forward and reverse pumps is in the neutral position, and hydraulic oil returns directly to port T through port P. Main relief valve 5 acts as a safety valve, limiting the maximum system pressure and preventing overpressure.

[0033] When the pump is in forward pumping mode, the forward and reverse pump manual operating valve 6a function is in working state, and the high-pressure oil enters the rodless chamber in the pumping cylinder 1 8 after passing the forward and reverse pump manual operating valve 6 and the pumping pilot control valve 7, and the pumping cylinder 1 8 extends; the pumping cylinder 1 8 is connected to the pumping cylinder 2 9 by a pipeline, and the two cylinders have the same cylinder diameter, rod diameter and stroke. During the extension of the pumping cylinder 1 8, the volume reduced in the rod chamber is the same as the volume increased in the rod chamber during the retraction of the pumping cylinder 2 9, and the two cylinders have the same working speed; when the pumping cylinder 1 8 is extended to the limit state, the second oil port 8.2 of the cylinder barrel pumping cylinder 1 is connected to the high-pressure oil in the rodless chamber, the first oil port 8.1 of the pumping cylinder 1 is connected to the low-pressure oil in the rod chamber, the cartridge valve 8.3 of the pumping cylinder 1 is opened, the T port of the cartridge valve 8.3 of the pumping cylinder 1 is connected to the high-pressure oil in the rodless chamber, and the swing cylinder pilot control valve 12 is switched to function a; pump When the oil feeding cylinder 2 9 is about to retract to the limit state, the high-pressure oil in the rod chamber passes through the third oil port 9.4 of the pumping cylinder 2 to the rodless chamber connected to the fourth oil port 9.5 of the pumping cylinder 2, playing a buffering role; during the extension of the pumping cylinder 18, the swing cylinder pilot control valve 12 is in the b working position, the swing cylinder 10 is extended to the limit position, the first pilot oil port 10.1 is connected to the high-pressure oil, which acts on the pilot chamber a of the pumping pilot control valve 7, and the swing cylinder 2 11 is retracted to the limit position; after the pumping cylinder 18 is extended to the limit position, the high-pressure oil is connected to the a chamber of the swing cylinder pilot control valve 12, the swing cylinder pilot control valve 12 is reversed, the swing cylinder 2 11 is extended, and the swing cylinder 10 is retracted; after the swing cylinder 11 is extended to the limit position, the pumping pilot control valve 7 is switched to the b function, the pumping cylinder 2 9 is extended, and the pumping cylinder 18 is retracted, completing a positive pump cycle;

[0034] When reverse pumping, the manual operation valve 6b of the forward and reverse pumps is in working state, and the other working states are similar to those of the forward pump.

[0035] like Figure 2 As shown, the hydraulic system of the variable displacement concrete pump for coal mines is characterized in that it includes a hydraulic oil tank 1, the outlet of the hydraulic oil tank 1 is connected to the first working port of the variable hydraulic pump 17, the variable hydraulic pump 17 is connected to the motor 3, the second working port of the variable hydraulic pump 17 is connected to the accumulator 16, the third working port of the variable hydraulic pump 17 is connected to the oil inlet of the forward and reverse pump manual operation valve 6, the oil return port of the forward and reverse pump manual operation valve 6 is connected to the inlet of the return oil circuit, the outlet of the return oil circuit is connected to the inlet of the hydraulic oil tank 1, and the variable hydraulic The fourth working port of the pump 17 is connected to the first working port of the pressure reducing valve 15, the fifth working port of the variable hydraulic pump 17 is connected to the first working port of the main overflow valve 5, the second working port of the main overflow valve 5 is connected to the return oil circuit, the third working port of the main overflow valve 5 is connected to the second working port of the pressure reducing valve 15, the forward and reverse pump manual operation valve 6 is connected to the swing cylinder assembly and the pumping cylinder assembly, an oil suction filter 2 is arranged between the hydraulic oil tank 1 and the variable hydraulic pump 17, and a radiator 13 and a return oil filter 14 are arranged on the return oil circuit in sequence.

[0036] Specifically, the forward and reverse pump manual operation valve 6 is an M-type middle position reversing valve, and the model of the variable hydraulic pump 17 is TBP63S-100R-2N*.

[0037] The pumping cylinder assembly includes a pumping cylinder 1 8 and a pumping cylinder 2 9 connected to a pumping pilot control valve 7 , and the swing cylinder includes a swing cylinder 10 , a swing cylinder 2 11 connected to a swing cylinder pilot control valve 12 .

[0038] like Figure 2 and 6 As shown, pumping cylinder 1 8 and pumping cylinder 2 9 are connected, and pumping cylinder 1 8 and pumping cylinder 2 9 are respectively provided with a first oil port 8.1 of pumping cylinder 1, a second oil port 8.2 of pumping cylinder 1, a third oil port 8.4 of pumping cylinder 1, a fourth oil port 8.5 of pumping cylinder 1 and a first oil port 9.1 of pumping cylinder 2, a first oil port 9.2 of pumping cylinder 2, a third oil port 9.4 of pumping cylinder 2, and a fourth oil port 9.5 of pumping cylinder 2.

[0039] Pumping cylinder 1's first oil port 8.1 is connected to pumping cylinder 1's cartridge valve 8.3, which is connected to pumping cylinder 1's second oil port 8.2. Pumping cylinder 1's third oil port 8.4 is connected to pumping cylinder 1's fourth oil port 8.5. Pumping cylinder 2 9 is identical to pumping cylinder 1 8.

[0040] The piston rod chambers of swing cylinders 10 and 11 are connected in series. They each have a first pilot oil port 10.1 and a second pilot oil port 11.1. The rodless chambers of swing cylinders 10 and 11 are connected to a swing cylinder pilot control valve 12. The inlet of this valve is connected to the outlet of the forward / reverse pump manual control valve 6 via a pipeline.

[0041] like Figure 2 As shown, the utility model provides a variable displacement concrete pump hydraulic system for coal mines. The improved hydraulic system fixed displacement hydraulic pump 4 is replaced by a variable displacement hydraulic pump 17 with total power control and positive flow control. The pump characteristic curve is shown as Figure 3 As shown, the total power control controls the maximum output power of the hydraulic system to ensure that during the concrete pumping process, when the system encounters abnormal conditions such as pipe blockage, the system pressure increases. At this time, the constant power starts to work and the hydraulic system flow is reduced to ensure that the total power required by the hydraulic system remains constant during the system operation, protecting the motor and preventing the motor from being blocked and damaged due to excessive power required by the hydraulic system 3.

[0042] A pressure reducing valve 15 is added between the outlet of the variable hydraulic pump 17 and the pump pilot control port. The pressure reducing valve 15 reduces the pump outlet pressure to a specified pressure Pi. The relationship between the control pressure Pi and the pump output flow is as follows: Figure 4As shown, the pump output flow rate increases with the increase of control pressure Pi.

[0043] In standby mode, pressure reducing valve 15 is adjusted to its minimum setting, motor 3 is started, and variable hydraulic pump 17 is driven to rotate. The hydraulic oil in hydraulic tank 1 is filtered through suction filter 2 and pressurized by variable hydraulic pump 17. A portion of the hydraulic oil enters accumulator 16 for filling, while the remaining portion passes through forward and reverse pump manual operation valve 6, radiator 13, and return oil filter 14 and returns to hydraulic tank 1. At this time, forward and reverse pump manual operation valve 6 is in the neutral position, and the hydraulic oil returns directly to port T through port P. The main relief valve 5 serves as a safety function, limiting the maximum system pressure and preventing system overpressure.

[0044] In the forward pumping condition, the forward and reverse pump manual operating valve 6a is in working state, and the pressure of the pressure reducing valve 15 is adjusted to the flow rate required by the system. Part of the high-pressure oil enters the accumulator 16, and the rest passes through the forward and reverse pump manual operating valve 6 and the pumping pilot control valve 7 and enters the rodless cavity in the pumping cylinder 1 8, and the pumping cylinder 1 8 extends; the pumping cylinder 1 8 is connected to the pumping cylinder 2 9 by a pipeline. The two cylinders have the same cylinder diameter, rod diameter, and stroke. During the extension of the pumping cylinder 1 8 , the volume reduced in the rod chamber is the same as the volume increased in the rod chamber during the retraction of the pumping cylinder 2 9, and the two cylinders work at the same speed; when the pumping cylinder 1 8 is extended to the limit state, the second oil port 8.2 of the cylinder barrel pumping cylinder 1 is connected to the high-pressure oil in the rodless chamber, the first oil port 8.1 of the pumping cylinder 1 is connected to the low-pressure oil in the rod chamber, the cartridge valve 8.3 of the pumping cylinder 1 is opened, the T port of the cartridge valve 8.3 of the pumping cylinder 1 is connected to the high-pressure oil in the rodless chamber, and the pilot control valve 1 of the swing cylinder is opened. 2 is switched to function a; when the pumping cylinder 2 9 is about to retract to the limit state, the high-pressure oil in the rod chamber passes through the third oil port 9.4 of the pumping cylinder 2 to the rodless chamber connected to the fourth oil port 9.5 of the pumping cylinder 2, playing a buffering role; during the extension of the pumping cylinder 1 8, the swing cylinder pilot control valve 12 is in the b working position, the hydraulic oil in the accumulator 16 is discharged, the swing cylinder 10 is extended to the limit position, and the first pilot oil port 10.1 is connected to the high-pressure oil, acting on the pumping cylinder 1 The pilot control valve 7 pilots the chamber a, and the swing cylinder 2 11 retracts to the limit position; after the pumping cylinder 1 8 extends to the limit position, the high-pressure oil is passed through the chamber a of the swing cylinder pilot control valve 12, and the swing cylinder pilot control valve 12 is reversed, the swing cylinder 2 11 extends, and the swing cylinder 10 retracts; after the swing cylinder 2 11 extends to the limit position, the pumping pilot control valve 7 switches to function b, the pumping cylinder 2 9 extends, and the pumping cylinder 1 8 retracts; completing a positive pump cycle.

[0045] The main function of the accumulator 16 is to ensure the swing speed of the swing cylinder when the pumping speed is low, that is, when the flow rate of the variable hydraulic pump 17 is low, reduce the impact of the swing cylinder reversal on the pumping system, and ensure pumping continuity.

[0046] When reverse pumping, the manual operation valve 6b of the forward and reverse pumps is in working state, and the other working states are similar to those of the forward pump.

[0047] The utility model provides a pumping device, comprising the variable displacement concrete pump hydraulic system for coal mines.

[0048] The above content is only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A variable displacement concrete pump hydraulic system for coal mines, characterized in that: The invention comprises a hydraulic oil tank (1), wherein the outlet of the hydraulic oil tank (1) is connected to the first working port of a variable hydraulic pump (17), the variable hydraulic pump (17) is connected to a motor (3), the second working port of the variable hydraulic pump (17) is connected to an accumulator (16), the third working port of the variable hydraulic pump (17) is connected to the oil inlet of a forward and reverse pump manual operation valve (6), the return oil port of the forward and reverse pump manual operation valve (6) is connected to the inlet of an oil return circuit, the outlet of the oil return circuit is connected to the inlet of the hydraulic oil tank (1), the fourth working port of the variable hydraulic pump (17) is connected to the first working port of a pressure reducing valve (15), the fifth working port of the variable hydraulic pump (17) is connected to the first working port of a main overflow valve (5), the second working port of the main overflow valve (5) is connected to the oil return circuit, the third working port of the main overflow valve (5) is connected to the second working port of the pressure reducing valve (15), and the forward and reverse pump manual operation valve (6) is connected to a swing cylinder assembly and a pumping cylinder assembly.

2. The variable displacement concrete pump hydraulic system for coal mines according to claim 1, characterized in that: The pumping cylinder assembly comprises a pumping cylinder 1 (8) and a pumping cylinder 2 (9), and the pumping cylinder 1 (8) and the pumping cylinder 2 (9) are connected.

3. The variable displacement concrete pump hydraulic system for coal mines according to claim 1, characterized in that: The swing cylinder assembly comprises a swing cylinder 1 (10) and a swing cylinder 2 (11), wherein the piston rod chambers of the swing cylinder 1 (10) and the swing cylinder 2 (11) are connected in series.

4. The variable displacement concrete pump hydraulic system for coal mines according to claim 1, characterized in that: An oil suction filter (2) is provided between the hydraulic oil tank (1) and the variable hydraulic pump (17).

5. The variable displacement concrete pump hydraulic system for coal mines according to claim 1, characterized in that: A radiator (13) and an oil return filter (14) are sequentially arranged on the oil return line.

6. The variable displacement concrete pump hydraulic system for coal mines according to claim 1, characterized in that: The forward and reverse pump manual operation valve (6) is an M-type mid-position reversing valve.

7. The variable displacement concrete pump hydraulic system for coal mines according to claim 1, characterized in that: In the standby state, the pressure reducing valve (15) is at the minimum state, the hydraulic oil in the hydraulic oil tank (1) is pressurized by the variable hydraulic pump (17), a part of it enters the accumulator (16), the forward and reverse pump manual operation valve (6) is in the middle functional state, and the other part directly returns to the oil return port through the oil inlet of the forward and reverse pump manual operation valve (6), and returns to the hydraulic oil tank (1) through the return oil line.

8. The variable displacement concrete pump hydraulic system for coal mines according to claim 1, characterized in that: In the forward pumping condition, the forward and reverse pump manual operating valve (6) is in the a-function working state, and the pressure of the pressure reducing valve (15) is adjusted to the flow rate required by the hydraulic system. Part of the high-pressure oil enters the accumulator (16), and the remaining high-pressure oil passes through the forward and reverse pump manual operating valve (6) and enters the pumping cylinder assembly and the swing cylinder assembly to complete a forward pumping cycle. In the reverse pumping condition, the forward and reverse pump manual operating valve (6) is in the b functional working state opposite to the a functional working state, and the pressure of the pressure reducing valve (15) is adjusted to the flow rate required by the hydraulic system. Part of the high-pressure oil enters the accumulator (16), and the remaining high-pressure oil passes through the forward and reverse pump manual operating valve (6) and enters the pumping cylinder assembly and the swing cylinder assembly to complete a reverse pumping cycle.

9. The variable displacement concrete pump hydraulic system for coal mines according to claim 1, characterized in that: The model of the variable hydraulic pump (17) is TBP63S-100R-2N*.

10. A pumping device, characterized in that: The invention comprises a variable displacement concrete pump hydraulic system for coal mines as described in any one of claims 1 to 9.

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