A control method and system for uniform injection of grease at the shield tail

Abstract

The present invention relates to a control method and system for uniform grease injection at the shield tail, and belongs to the technical field of shield tail grease injection system control. The present invention measures the grease consumption in the grease barrel in real time, determines the injection status of the injection point according to the grease consumption in the grease barrel, thereby controlling the air intake of the pneumatic pump, adjusting the pumping frequency of the pneumatic pump, and thus making the grease injection at each injection point uniform. The control method of the present invention is simple and easy to implement, and solves the problems of inaccurate grease injection at the shield tail, uneven grease injection at the pressure sealing ring, and asynchronous grease injection. It effectively prevents formation water, mortar, and solids from entering the shield body, reduces the friction between the pipe segment and the shield tail, prolongs the life of the tail brush, reduces the operating level requirements for the shield driver, and reduces construction costs.

Description

Technical Field

[0001] The invention relates to a control method and system for uniformly injecting grease into a shield tail, belonging to the technical field of shield tail grease injection system control. Background Art

[0002] During shield construction, the annular gaps formed by excavation require timely grouting. The slurry requires a certain level of support pressure, necessitating effective sealing between the shield tail and the segments. Currently, shield machines weld multiple tail brushes to the shield tail area, pumping grease between the brushes to form a pressure seal ring, thereby sealing the gap between the shield tail and the segments and preventing formation water, mortar, and solids from entering the shield body. As the shield machine advances, grease adheres to the segments, forming a thick film, which reduces friction between the segments and the shield tail and extends the life of the tail brushes. Controlling the grease injection volume is key to the shield tail grease system and is a decisive factor in establishing effective shield tail support pressure and achieving good sealing and lubrication.

[0003] The existing shield tail grease injection system control method adopts two modes: time control and stroke control. The two control modes can be switched on the host computer. In the time control mode, the maximum pressure, interval time, etc. are set through the pressure detection device at the shield tail injection port. After reaching the set pressure, the system switches to the next path according to the interval time. In the stroke control mode, the stroke, injection times, etc. are set through the host computer. After the injection point under the stroke reaches the set number of times, the system switches to the next path. Due to the errors of the pressure detection device and the significant influence of the environment and temperature on the viscosity and performance of the grease, it is not possible to guarantee that the amount of grease counted by the stroke switch is constant each time. Therefore, the disadvantages of both control modes are that they cannot accurately control the injection volume of each injection point in the pressure sealing ring, and cannot ensure that the grease is evenly injected into each pressure sealing ring. Grease injection is asynchronous, injection is too fast, resulting in the risk of breakdown of the tail brush, and injection is too slow, resulting in the inability to establish support pressure. It cannot effectively prevent formation water, mortar, and solids from entering the shield body. In addition, the shield driver's operating level and experience are extremely high.

[0004] For example, the Chinese utility model patent document with publication number CN211083585U discloses a shield tail grease system for a large-diameter shield machine. The document describes the existing shield tail grease injection system and two automatic control modes: pressure control and stroke control. During actual tunneling, in the automatic mode, inaccurate pressure feedback leads to insufficient shield tail grease injection, which ineffectively prevents formation water, mortar, and solids from entering the shield body, accelerates the wear of the shield tail brush, and increases the frequency of brush replacement. Therefore, a large-diameter shield tail grease system was designed to reduce control errors by optimizing the piping layout and pressure sensor positions of different pressure sealing rings. For example, the Chinese invention patent application document with application publication number CN114635699A discloses an adaptive shield tail grease injection system. This system adds multiple distance sensors to the pressure sealing rings to accurately measure the pressure chamber volume, thereby ensuring the grease injection volume for each pressure chamber. However, it cannot guarantee the injection volume at each injection point or the uniform injection volume for each pressure sealing ring, and the cost is relatively high.

[0005] Therefore, the current shield tail grease injection system cannot guarantee that the injection amount at each injection point is uniform, and the control through multiple distance sensors is bound to increase costs. Summary of the Invention

[0006] The purpose of the present invention is to provide a control method and system for uniform injection of grease at the shield tail, so as to solve the problem of uneven injection at each injection point existing in the current time control and stroke control.

[0007] In order to solve the above technical problems, the present invention provides a control method for uniform injection of grease at the shield tail, which comprises the following steps:

[0008] 1) Measure the grease consumption in the grease barrel;

[0009] 2) Control the air intake of the pneumatic pump according to the grease consumption, and then control the pumping frequency of the pneumatic pump to ensure that the grease is injected evenly at each injection point.

[0010] The present invention measures grease consumption in the grease barrel in real time and determines the injection status of the injection points based on the grease consumption in the grease barrel. This method controls the air intake of the pneumatic pump and adjusts the pumping frequency of the pneumatic pump, thereby ensuring uniform grease injection at each injection point. The control method of the present invention is simple and easy to implement, and solves the problems of inaccurate grease injection at the shield tail, uneven grease injection at the pressure sealing ring, and asynchronous grease injection. It effectively prevents formation water, mortar, and solids from entering the shield body, reduces friction between the segments and the shield tail, extends the life of the tail brush, and reduces the operating requirements of the shield operator, while also reducing construction costs.

[0011] Furthermore, the specific control process of step 2) is as follows:

[0012] A. Determine the injection volume for each injection point in each cavity based on the injection volume requirements under each cavity stroke and the number of injection points. Determine the corresponding injection frequency based on the injection volume and the pumping volume of the pneumatic grease pump at one time. This injection frequency is used as the set injection frequency for the injection point.

[0013] B. In the set cycle, the grease consumption in the grease barrel is used to determine whether each injection point has reached the corresponding set injection number. If not, the air intake of the pneumatic pump is controlled to increase in the next cycle so that the injection number of the injection point meets the requirement; if it exceeds the corresponding set injection number, the air intake of the pneumatic pump is controlled to decrease in the next cycle so that the injection number of the injection point is reduced.

[0014] The present invention determines the injection times of each injection point according to the injection volume requirement under each cavity stroke and the number of injection points, converts the detected grease consumption into the injection times, and controls the air intake of the pneumatic pump according to whether the injection times of the injection point within a set period meet the requirements, making the control of the starting pump simpler and easier to operate.

[0015] Furthermore, the method further comprises detecting the pressure at each injection point, and issuing an alarm and / or stopping the grease injection when the pressure exceeds a set threshold.

[0016] The present invention performs pressure detection on the injection point, and by setting pressure alarm and shutdown values, an alarm is issued or the machine is stopped when the pressure is reached, which can effectively prevent the shield tail brush from being penetrated by excessive pressure at the injection point.

[0017] Furthermore, the grease consumption in the grease barrel is measured by a pull rope liquid level sensor arranged in the grease barrel.

[0018] The present invention uses a pull-rope liquid level sensor to measure the grease consumption in the grease barrel, which can accurately measure the grease consumption and further improve the control accuracy.

[0019] Furthermore, the step 2) is implemented using a PID control method.

[0020] The present invention adopts the PID control method to control the air intake of the pneumatic pump, which can achieve the control target accurately and quickly.

[0021] The present invention also provides a control system for uniform injection of shield tail grease, which includes an electric regulating valve controller, a pneumatic grease pump controller and a detection element; the detection element is used to detect the grease consumption in the grease barrel; the electric regulating valve controller is used to control the electric regulating valve arranged at the air source inlet of the pneumatic pump according to the detected grease consumption, so as to control the air intake of the pneumatic pump; the pneumatic grease pump controller is used to control the pumping frequency of the pneumatic pump according to the air intake, so that the grease at each injection point is injected evenly.

[0022] The present invention uses a detection element to measure the grease consumption in the grease barrel in real time. The electric regulating valve controller determines the injection status of the injection point based on the grease consumption in the grease barrel, thereby controlling the air intake of the pneumatic pump. The pneumatic grease pump controller adjusts the pumping frequency of the pneumatic pump, thereby ensuring uniform grease injection at each injection point. The control method of the present invention is simple and easy to implement, and solves the problems of inaccurate grease injection at the shield tail, uneven grease injection at the pressure sealing ring, and asynchronous grease injection. It effectively prevents formation water, mortar, and solids from entering the shield body, reduces friction between the segments and the shield tail, extends the life of the tail brush, and reduces the operating requirements of the shield operator, while also reducing construction costs.

[0023] Furthermore, the control process adopted by the electric regulating valve controller and the pneumatic pump grease controller is as follows:

[0024] A. Determine the injection volume for each injection point in each cavity based on the injection volume requirements under each cavity stroke and the number of injection points. Determine the corresponding injection frequency based on the injection volume and the pumping volume of the pneumatic grease pump at one time. This injection frequency is used as the set injection frequency for the injection point.

[0025] B. Within the set cycle, the grease consumption in the grease barrel is used to determine whether each injection point has reached the corresponding set injection number. If not, the electric control valve controller controls the air intake of the pneumatic pump to increase in the next cycle so that the injection number of the injection point meets the requirement; if it exceeds the corresponding set injection number, the electric control valve controller controls the air intake of the pneumatic pump to decrease in the next cycle so that the injection number of the injection point decreases.

[0026] The present invention determines the injection times of each injection point according to the injection volume requirement under each cavity stroke and the number of injection points, converts the detected grease consumption into the injection times, and controls the air intake of the pneumatic pump according to whether the injection times of the injection point within a set period meet the requirements, making the control of the starting pump simpler and easier to operate.

[0027] Furthermore, the control system also includes a pressure sensor arranged at each injection point to detect the pressure at each injection point and feed back the pressure value to the pneumatic grease pump controller. The pneumatic grease pump controller is used to alarm and / or control the pneumatic pump to stop grease injection when the pressure value exceeds a set threshold.

[0028] The present invention performs pressure detection on the injection point, and by setting pressure alarm and shutdown values, an alarm is issued or the machine is stopped when the pressure is reached, which can effectively prevent the shield tail brush from being penetrated by excessive pressure at the injection point.

[0029] Furthermore, the detection element is a pull rope liquid level sensor for being arranged in the grease barrel.

[0030] The present invention uses a pull-rope liquid level sensor to measure the grease consumption in the grease barrel, which can accurately measure the grease consumption and further improve the control accuracy.

[0031] Furthermore, the electric regulating valve controller adopts PID control mode.

[0032] The present invention adopts the PID control method to control the air intake of the pneumatic pump, which can achieve the control target accurately and quickly. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the shield tail grease uniform injection control system of the present invention;

[0034] Figure 2 This is a control block diagram of the shield tail grease uniform injection control system of the present invention;

[0035] Among them, 1 is a pneumatic grease pump, 2 is a pull rope liquid level sensor, 3 is an electric regulating valve, 4 is a manual ball valve, 5 is a pressure sensor, and 6 is a pneumatic ball valve. DETAILED DESCRIPTION

[0036] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0037] Example of a control system for uniform grease injection at the shield tail:

[0038] The present invention measures the grease consumption in the grease barrel in real time through a detection element, and the electric regulating valve controller determines the injection situation of the injection point according to the grease consumption in the grease barrel, thereby controlling the air intake of the pneumatic pump, and adjusting the pumping frequency of the pneumatic pump through the pneumatic grease pump controller, thereby ensuring uniform grease injection at each injection point.

[0039] Specifically, the control system for uniform grease injection of the tail shield of the present invention includes a pneumatic grease pump controller, an electric regulating valve controller, a detection element, an electric regulating valve 3 for being set at the air source inlet of the pneumatic pump, and a manual ball valve 4, a pressure sensor 5 and a pneumatic ball valve 6 set at each injection point of each cavity of the shield tail, wherein the detection element is used to detect the grease consumption in the pneumatic grease pump, such as Figure 1As shown, the detection element in this embodiment is a pull-wire level sensor 2, which is installed in the grease barrel of a pneumatic grease pump. The shield tail is provided with a front cavity, a middle cavity, and a rear cavity. Each cavity is provided with multiple grease injection points. Grease is pumped by a pneumatic grease pump 1 to the pressure seal rings in the front, middle, and rear cavities of the shield tail. Each grease injection point is equipped with a manual ball valve 4, a pressure sensor 5, and a pneumatic ball valve 6. The manual ball valve 4 can be used to manually close the grease injection channel in the event of component damage or system maintenance. The pressure sensor 5 can detect the pressure at each injection point and send the detected pressure to the pneumatic grease pump controller. It can also display the pressure of each injection point in real time on the host computer. By setting pressure alarm and shutdown values, an alarm is issued when the pressure at an injection point reaches the pressure alarm value. When the pressure at an injection point reaches the shutdown value, the pneumatic grease pump controller controls the pneumatic pump to stop and grease is not injected at that injection point to prevent excessive pressure in the pressure seal ring from piercing the shield tail brush. The pneumatic ball valve 6 is used to switch between manual and automatic control modes. The pneumatic grease pump controller includes a grease pump start / stop button and a maintenance button. The start / stop button can control the start and stop of the grease pump. When the maintenance button is turned on, the host computer cannot control the grease pump to prevent misoperation when changing barrels or repairing the pump.

[0040] The present invention uses a pull rope liquid level sensor 2 in the grease barrel of the pneumatic pump to accurately measure the grease consumption. According to the measured grease consumption, the electric regulating valve controller controls the electric regulating valve 3 to adjust the air intake of the pneumatic pump. Figure 2 As shown, the present invention adopts a PID control method to control the valve opening of the electric regulating valve. The electric regulating valve controller in this embodiment can be implemented by a PLC. Given a constant air source pressure at the pump head, the PLC can use real-time PID to adjust the valve opening according to the change in liquid level (i.e., grease consumption), control the air source flow rate, and thus control the pumping frequency. The specific control method adopted in this embodiment is as follows:

[0041] Assuming that the front cavity, middle cavity and rear cavity are set to an injection volume of (Y) ml / min under a stroke of (X) mm, each cavity automatically calculates the injection volume (Z) ml / xs and the injection frequency n times / xs of each injection point of each cavity. According to the feedback result of the grease injection volume from the rope liquid level sensor 2, the PLC converts it into the injection frequency, and the real-time PID adjusts the valve opening to control the air source flow to achieve the injection frequency n times / xs. xs is the set period, also called the sampling period. Only one point is injected in each sampling period.

[0042] For example, if the stroke is set to 100mm, the front chamber needs to be injected at 2000ml / min. The front chamber has 10 injection points in total, and the pneumatic grease pump pumps 100m once. It can be calculated that each injection point in the front chamber within 100mm needs to be injected at 200ml / 6s, that is, each injection point needs to be pumped twice / 6s, and the sampling period is 6s. During the real-time control process, if the count within the sampling period (6s) does not reach the specified number (2 times), the electric control valve controller controls the valve opening of the electric control valve 3 to increase in the next sampling period, so that the count within the next sampling period is +1 based on the specified number of cycles. If the sampling period exceeds the specified number (2 times), the valve opening is controlled to decrease, so that the count within k sampling periods is 0. This count represents the deviation. If a cycle is greater than 2 times, it is a positive number, and if it is less than 2 times, it is a negative number. Therefore, when the count within k periods is 0, it means that the deviation within k periods is 0. This reciprocating and automatic adjustment allows the front chamber to evenly inject 2000ml within 1 minute with a stroke of 100mm, ensuring that the support pressure is stably established in the sealing pressure ring, avoiding problems such as excessive injection in each chamber causing instantaneous pressure increase and penetration of the tail brush, and excessive injection causing inability to build up pressure normally.

[0043] An embodiment of a method for controlling uniform injection of grease into the shield tail:

[0044] The present invention measures grease consumption in a grease barrel in real time and determines the injection status of each injection point based on the grease consumption. This method controls the air intake of the pneumatic pump and adjusts the pumping frequency of the pneumatic pump, thereby ensuring uniform grease injection at each injection point. The specific implementation process of this method has been described in detail in the control system embodiment and will not be repeated here.

Claims

1. A method for controlling uniform injection of grease at the shield tail, characterized in that: The control method comprises the following steps: 1) Measure the grease consumption in the grease barrel; 2) Control the air intake of the pneumatic pump according to the grease consumption, and then control the pumping frequency of the pneumatic pump to ensure uniform grease injection at each injection point; The specific control process of step 2) is as follows: A. Determine the injection volume for each injection point in each cavity based on the injection volume requirements under each cavity stroke and the number of injection points. Determine the corresponding injection frequency based on the injection volume and the pumping volume of the pneumatic grease pump at one time. This injection frequency is used as the set injection frequency for the injection point. B. Within the set cycle, determine whether each injection point has reached the corresponding set injection number based on the grease consumption in the grease barrel. If not, the air intake of the pneumatic pump is controlled to increase in the next cycle so that the injection number of the injection point meets the requirement; if it exceeds the corresponding set injection number, the air intake of the pneumatic pump is controlled to decrease in the next cycle so that the injection number of the injection point is reduced; the set cycle refers to the injection time required for an injection point.

2. The method for controlling uniform injection of grease at the shield tail according to claim 1, characterized in that: The method further comprises detecting the pressure of each injection point, and issuing an alarm and / or stopping the grease injection when the pressure exceeds a set threshold.

3. The method for controlling uniform injection of grease at the shield tail according to claim 1, characterized in that: The grease consumption in the grease barrel is measured by a pull rope liquid level sensor arranged in the grease barrel.

4. The method for controlling uniform injection of grease at the shield tail according to claim 1, characterized in that: The step 2) is implemented using a PID control method.

5. A control system for uniform injection of grease at the shield tail, characterized in that: The control system includes an electric regulating valve controller, a pneumatic grease pump controller, and a detection element; the detection element is used to detect the grease consumption in the grease barrel; the electric regulating valve controller is used to control the electric regulating valve provided at the air source inlet of the pneumatic pump according to the detected grease consumption, thereby controlling the air intake of the pneumatic pump; the pneumatic grease pump controller is used to control the pumping frequency of the pneumatic pump according to the air intake, so that the grease is evenly injected at each injection point; The control process adopted by the pneumatic pump grease controller is as follows: A. Determine the injection volume for each injection point in each cavity based on the injection volume requirements under each cavity stroke and the number of injection points. Determine the corresponding injection frequency based on the injection volume and the pumping volume of the pneumatic grease pump at one time. This injection frequency is used as the set injection frequency for the injection point. B. Within the set cycle, the grease consumption in the grease barrel is used to determine whether each injection point has reached the corresponding set injection number. If not, the electric control valve controller controls the air intake of the pneumatic pump to increase in the next cycle so that the injection number of the injection point meets the requirement; if it exceeds the corresponding set injection number, the electric control valve controller controls the air intake of the pneumatic pump to decrease in the next cycle so that the injection number of the injection point is reduced. The set cycle refers to the injection time required for an injection point.

6. The control system for uniform grease injection at the shield tail according to claim 5, characterized in that: The control system also includes a pressure sensor arranged at each injection point to detect the pressure at each injection point and feed the pressure value back to the pneumatic grease pump controller. The pneumatic grease pump controller is used to alarm and / or control the pneumatic pump to stop grease injection when the pressure value exceeds a set threshold.

7. The control system for uniform grease injection at the shield tail according to claim 5, characterized in that: The detection element is a pull rope liquid level sensor used to be arranged in the grease barrel.

8. The control system for uniform grease injection at the shield tail according to claim 5, characterized in that: The electric regulating valve controller adopts PID control mode.

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