Liquid filling equipment and liquid filling method

Abstract

The invention relates to liquid filling equipment and a liquid filling method. The liquid filling equipment comprises a control system, a liquid storage system and a filling system, the liquid storage system comprises a liquid storage tank, a weighing device, a pressure regulating device and a pressure sensor; the liquid storage tank is used for containing to-be-filled liquid and reserving a top space; the weighing device is used for weighing the real-time liquid weight in the liquid storage tank; the pressure sensor is used for measuring the real-time headspace pressure of the headspace; the pressure regulating device is communicated with the top space of the liquid storage tank and is used for regulating the headspace pressure of the liquid storage tank; the filling system comprises a filling head and a moving mechanism; the liquid storage tank is communicated with the filling head through the discharging pipeline, and the moving mechanism is used for driving the filling head to move forwards and backwards; the control system is respectively connected with the weighing device, the pressure sensor, the pressure regulating device and the filling system; and the control system controls the pressure adjusting device to adjust the headspace pressure according to the liquid weight, and the headspace pressure rises along with reduction of the liquid weight of the liquid storage tank. In the filling process, the accuracy of the amount of liquid filled into the packaging container is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of equipment, and in particular to a liquid filling device and a liquid filling method. Background Art

[0002] Liquid filling machines are used to put liquids or pastes and other fluids of different viscosities into packaging bottles or packaging boxes. The liquid inlet control of the liquid storage tank of the existing liquid filling machine is carried out by detecting the liquid level in the tank with a liquid level meter, and feeding back to the controller to control the opening and closing of the pneumatic diaphragm valve using a switch signal.

[0003] CN109592623A discloses a liquid filling machine, comprising a liquid storage tank, a liquid storage pipe, a pneumatic solenoid valve, a liquid pressure regulating and controlling device, a pressure controller and a plurality of filling heads. The liquid storage tank and the liquid storage pipe are both closed structures. An air inlet is provided on the top or upper side of the liquid storage tank, and the air inlet is connected to a compressed gas source through an air transmission pipeline. The pneumatic solenoid valve is arranged on the air transmission pipeline. A liquid outlet is provided on the bottom or lower side of the liquid storage tank, and the liquid outlet is connected to the liquid storage pipe through an infusion pipeline. The liquid pressure regulating and controlling device is arranged on the infusion pipeline, and the liquid pressure regulating and controlling device is connected to the pressure controller, and the pressure controller is electrically connected to the pneumatic solenoid valve. The pressure controller is used to set the filling pressure and monitor the pressure in the liquid pressure regulating and controlling device, and control the action of the pneumatic solenoid valve according to the set and monitored pressure values. The plurality of filling heads are respectively connected to the liquid storage pipe, and the liquid pressure regulating and controlling device is a buffer tank.

[0004] In the prior art, the liquid in the buffer tank continuously enters the filling head, causing the liquid level to drop. In order to ensure the stability of the liquid level, it is necessary to continuously replenish the liquid from the liquid storage tank. Between the discharge and inflow of the buffer tank, the headspace volume of the buffer tank is constantly changing, and it is necessary to continuously feed or discharge nitrogen to keep the pressure of the buffer tank stable, resulting in the pressure in the buffer tank constantly fluctuating. The constant fluctuation of the pressure in the buffer tank leads to low filling volume accuracy.

[0005] Therefore, there is an urgent need for a liquid filling device and a liquid filling method to solve the above technical problems. Summary of the invention

[0006] The purpose of the present invention is to provide a liquid filling device and a liquid filling method so as to solve the problem of low filling volume accuracy.

[0007] To achieve the above objectives, one object of the present invention is to provide a liquid filling device, including a control system, a liquid storage system and a filling system;

[0008] The liquid storage system comprises a liquid storage tank, a weighing device, a pressure regulating device and a pressure sensor; the liquid storage tank is used to hold the liquid to be filled and leave a head space; the weighing device is used to weigh the real-time liquid weight of the liquid storage tank; the pressure sensor is used to measure the real-time headspace pressure of the headspace; the pressure regulating device is connected to the headspace of the liquid storage tank and is used to adjust the headspace pressure of the liquid storage tank;

[0009] The filling system comprises a filling head and a moving mechanism; the liquid storage tank is connected to the filling head through a discharge pipeline, and the moving mechanism is used to drive the filling head to move forward and reverse;

[0010] The control system is respectively connected with the weighing device, the pressure sensor, the pressure regulating device and the filling system;

[0011] The control system controls the pressure regulating device to adjust the headspace pressure according to the weight of the liquid, wherein the headspace pressure increases as the weight of the liquid in the liquid storage tank decreases.

[0012] Preferably, the filling head comprises a liquid dispenser, a plurality of filling needles connected to the liquid dispenser, and a filling valve provided on the filling needles, and the control system is connected to the filling valve.

[0013] Preferably, the discharge pipeline is provided with a discharge valve, and the control system is connected to the filling valve.

[0014] Preferably, the liquid storage tank is provided with a feed pipeline, the feed pipeline is provided with a feed valve, and the feed valve is connected to the control system.

[0015] Preferably, the liquid storage tank is provided with an exhaust valve for exhausting the gas in the liquid storage tank.

[0016] Preferably, the liquid storage tank is provided with a stirrer for stirring the liquid in the liquid storage tank.

[0017] Another object of the present invention is a liquid filling method, using the liquid filling device described above, comprising the following steps:

[0018] S120, the liquid storage tank is filled with liquid, and after the liquid filling is completed, the liquid storage tank is sealed;

[0019] S140, the control system obtains the initial liquid weight in the liquid storage tank measured by the weighing device and the initial headspace pressure measured by the pressure sensor, and controls the pressure regulating device to adjust the headspace pressure;

[0020] S160, liquid filling, including:

[0021] Filling head moves forward: the moving mechanism drives the filling head to move forward and move synchronously with the packaging container, the filling head is opened, and the filling head fills liquid into the packaging container;

[0022] Filling head return: After filling is completed, the filling head is closed, and the moving mechanism drives the filling head to move in the reverse direction to the initial position;

[0023] Determine the pressure difference to be adjusted: the control system obtains the real-time liquid weight of the liquid storage tank measured by the weighing device to calculate the corresponding required headspace pressure, the control system obtains the real-time headspace pressure measured by the pressure sensor, and determines the pressure difference to be adjusted according to the required headspace pressure and the real-time headspace pressure;

[0024] Pressure regulation by pressure regulating device: Control the pressure regulating device to adjust the headspace pressure according to the pressure difference to be adjusted;

[0025] S180, repeat step S160 until the liquid weight in the liquid storage tank is less than the set minimum weight threshold, and then turn off the liquid filling equipment.

[0026] Preferably, the required headspace pressure and the real-time liquid weight are calculated as follows:

[0027] Y=aX 2 -bX+c

[0028] Where Y is the required headspace pressure; X is the weight of the liquid in the tank; a / b / c are the normal coefficients.

[0029] Preferably, the process of "determining the pressure difference to be adjusted and regulating the pressure by the pressure regulating device" in S160 is performed simultaneously with the process of "returning the filling head".

[0030] Preferably, the step of determining the pressure difference to be adjusted according to the required headspace pressure and the real-time headspace pressure comprises:

[0031] Pressure difference to be adjusted = required headspace pressure - real-time headspace pressure.

[0032] Preferably, the step of determining the pressure difference to be adjusted according to the required headspace pressure and the real-time headspace pressure comprises: setting a pressure difference threshold in the control system,

[0033] When the required headspace pressure minus the real-time headspace pressure ≥ the pressure difference threshold, the pressure difference to be adjusted = the required headspace pressure minus the real-time headspace pressure; or

[0034] When the required headspace pressure minus the real-time headspace pressure is less than the pressure difference threshold, the pressure difference to be adjusted = 0.

[0035] As can be seen from the above, the technical solution provided by the present invention adopts a pressure sensor to detect the headspace pressure of the top space, and increases the headspace pressure of the liquid storage tank according to the decrease in liquid weight, so that the outlet pressure of the liquid storage tank and the discharge pipe remains unchanged, and the liquid flow rate in the discharge pipe remains unchanged, thereby improving the accuracy of the liquid amount filled into the packaging container during the time pressure filling process. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of a liquid filling equipment.

[0037] In the figure:

[0038] 110, liquid storage tank; 111, head space; 120, weighing device; 130, pressure regulating device; 131, air supply pipe; 132, proportional valve; 133, air storage tank; 140, pressure sensor; 150, discharge pipeline; 151, discharge valve; 160, exhaust valve; 170, agitator; 180, feed pipeline; 181, feed valve;

[0039] 200, filling system; 210, filling head; 211, diverter; 212, filling needle; 213, filling valve; 220, moving mechanism;

[0040] 300. Control system;

[0041] 400. Track system;

[0042] 1. Filling container. DETAILED DESCRIPTION

[0043] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. It is understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It is also necessary to explain that, for ease of description, only the parts related to the present invention are shown in the accompanying drawings, rather than all.

[0044] Some directional words are defined in the present invention. Unless otherwise specified, the directional words used, such as "up", "down", "left", "right", "inside" and "outside", are used to facilitate understanding and therefore do not constitute a limitation on the scope of protection of the present invention.

[0045] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0046] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0047] Example 1

[0048] Reference Figure 1 , an embodiment of a liquid filling device of the present invention is shown. The liquid filling device includes a liquid storage system, a filling system 200 and a control system 300 .

[0049] The liquid storage system includes a liquid storage tank 110, a weighing device 120, a pressure regulating device 130 and a pressure sensor 140. In this embodiment, the liquid storage tank 110 is preferably a cylindrical stainless steel storage tank. The liquid storage tank 110 is used to store the liquid to be filled and leave a head space. The weighing device 120 is used to weigh the real-time liquid weight of the liquid storage tank 110. In this embodiment, the weighing device 120 is a foot weighing device, and the liquid storage tank 110 is placed on the weighing device 120. After the weighing device 120 and the liquid storage tank 110 are installed, the weighing device 120 is peeled when no liquid is stored in the liquid storage tank 110. At this time, the weight information sent by the weighing device 120 is the liquid weight. The pressure sensor 140 is arranged at the top of the liquid storage tank 110, and is used to measure the real-time headspace pressure of the headspace 111. The pressure regulating device 130 is connected to the headspace of the liquid storage tank 110, and is used to adjust the headspace pressure of the liquid storage tank 110.

[0050] In this embodiment, Figure 1 As shown, the pressure regulating device 130 includes a gas storage tank 133, a gas supply pipe 131 and a proportional valve 132. The gas storage tank 133 is connected to the liquid storage tank 110 through the gas supply pipe 131, and the proportional valve 132 is installed on the gas supply pipe 131. In this embodiment, the gas storage tank 133 is used to store nitrogen, which has the advantages of being cheap and pollution-free. The proportional valve 132 is connected to the control system 300, and the control system 300 controls the opening and closing of the proportional valve 132 to control the gas storage tank 133 to fill the top space with nitrogen through the gas supply pipe 131.

[0051] The filling system 200 includes a filling head 210 and a moving mechanism 220; the liquid storage tank 110 is connected to the filling head 210 through the discharge pipeline 150, and the moving mechanism 220 is used to drive the filling head 210 to move forward and backward. Figure 1As shown, during the filling process, the packaging container 1 to be filled is placed on the track system 400, and the track system 400 drives the packaging container 1 to move in one direction, which is the moving direction of the packaging container 1. The forward direction in the present invention refers to the moving direction of the packaging container 1, that is, Figure 1 The direction indicated by the arrow in the middle refers to the direction opposite to the moving direction of the packaging container 1.

[0052] The control system 300 is connected to the weighing device 120 , the pressure sensor 140 , the pressure regulating device 130 , and the filling system 200 , respectively.

[0053] The control system 300 controls the pressure regulating device 130 to adjust the headspace pressure of the top space 111 according to the liquid weight measured by the weighing device 120, wherein the headspace pressure increases as the liquid weight decreases.

[0054] The liquid filling equipment of the present invention uses a pressure sensor 140 to detect the headspace pressure of the top space 111, and increases the headspace pressure of the liquid storage tank according to the decrease in liquid weight, so that the outlet pressure of the liquid storage tank 110 and the discharge pipe 150 remains unchanged, and the liquid flow rate in the discharge pipe 150 remains unchanged, thereby improving the accuracy of the liquid amount filled into the packaging container during the time pressure filling process.

[0055] The filling head 210 includes a liquid dispenser 211, a plurality of filling needles 212 connected to the liquid dispenser 211, and a filling valve 213 provided on the filling needles 212. The control system 300 is connected to the filling valve 213. The amount of liquid supplied to the liquid container is precisely controlled by switching the filling valve 213. The filling valve 213 is a switch device for opening or closing the liquid supply of the filling needle 212, and is not limited to a valve.

[0056] As a preferred embodiment, the discharge pipeline 150 is provided with a discharge valve 151, and the control system 300 is connected to the discharge valve 151. During filling, the discharge valve 151 is opened and is normally open during the filling process. When the liquid storage tank 110 is filled with liquid, the discharge valve 151 is closed.

[0057] The liquid storage tank 110 is provided with a feed line 180, and the feed line 180 is provided with a feed valve 181, and the feed valve 181 is connected to the control system 300. When feeding is required, the control system 300 controls the opening of the feed line 180 through the feed valve 181, and controls the feeding speed according to different liquid requirements. When the feeding is completed, the control system 300 closes the feed valve 181, thereby sealing the liquid storage tank.

[0058] The liquid storage tank 110 is provided with an exhaust valve 160. When the liquid storage tank 110 is filled with liquid, the exhaust valve 160 is opened to discharge the excess gas in the liquid storage tank 110. The exhaust valve 160 is connected to the control system 300. When the liquid storage tank 110 is filled with liquid, the exhaust valve 160 is opened to discharge the excess nitrogen in the liquid storage tank 110 out of the liquid storage tank 110.

[0059] The liquid storage tank 110 is provided with an agitator 170 for agitating the liquid in the liquid storage tank 110 to ensure that the liquid is continuously in a uniformly mixed state.

[0060] The electrical connection between the control system 300 and the proportional valve 132, the pressure sensor 140, the feed valve 181, the exhaust valve 160, the weighing device 120, the discharge valve 151, the filling valve 213, and the drive mechanism 220 can be wired or wirelessly connected. The connection wires are omitted in the drawings of the embodiments of the present invention.

[0061] Example 2

[0062] The present invention also provides a liquid filling method, using the liquid filling device described in the above embodiment, the steps of which include:

[0063] S120, liquid is fed into the liquid storage tank 110, and after the feeding is completed, the liquid storage tank 110 is sealed. Liquid is fed into the liquid storage tank 110, and the control system 300 stops feeding liquid and seals the liquid storage tank 110, i.e., closes the feed valve 181, the exhaust valve 160, etc., when the weight of the liquid storage tank 110 reaches the set maximum weight threshold according to the weight measured by the weighing device 120.

[0064] S140, the control system 300 obtains the initial liquid weight in the liquid storage tank 300 measured by the weighing device 120 and the initial headspace pressure measured by the pressure sensor 140, and the control system 300 controls the pressure regulating device 130 to adjust the headspace pressure.

[0065] S160, liquid filling, including:

[0066] The filling head 210 moves forward: the moving mechanism 220 drives the filling head 210 to move forward and move synchronously with the packaging container, the filling head 210 is opened, and the filling head 210 fills the packaging container with liquid.

[0067] Return of the filling head 210: After the filling is completed, the filling head 210 is closed, and the moving mechanism drives the filling head 210 to move in the reverse direction.

[0068] Determine the pressure difference to be adjusted: the control system 300 obtains the real-time liquid weight of the liquid storage tank 110 measured by the weighing device 120 to calculate the corresponding required headspace pressure, the control system 300 obtains the real-time headspace pressure measured by the pressure sensor, and determines the pressure difference to be adjusted according to the required headspace pressure and the real-time headspace pressure. In this embodiment, determining the pressure difference to be adjusted according to the required headspace pressure and the real-time headspace pressure includes: determining the pressure difference between the required headspace pressure and the real-time headspace pressure as the pressure difference to be adjusted, that is, the pressure difference to be adjusted = the required headspace pressure - the real-time headspace pressure.

[0069] Pressure regulation by the pressure regulating device: The control system 300 controls the pressure regulating device 130 to adjust the headspace pressure according to the pressure difference to be adjusted.

[0070] The filling process of the present invention adopts the time pressure method: when the moving mechanism 220 drives the filling head 210 to move forward, the filling head 210 moves synchronously with the packaging container, and the filling head 210 is opened and closed at a fixed time to fill a fixed amount of liquid into the packaging container. The formula for volume flow is Q = V·S, where Q represents the volume flow of the fluid (m 3 / s), V represents the average flow rate of the fluid (m / s), and S represents the cross-sectional area of ​​the liquid pipeline (㎡). Filling volume = T·Q = T·V·S, where T is the time between the opening and closing of the filling head 210. The filling requirement is that the filling volume remains unchanged. Since T and S remain unchanged in the formula, this ensures that V remains unchanged during each filling process. In order to keep V unchanged, it is necessary to keep the outlet pressure at the connection between the liquid storage tank 110 and the discharge pipeline 150 unchanged. The outlet pressure is composed of the liquid static pressure and the headspace pressure of the liquid storage tank. As the filling proceeds, the weight of the liquid in the liquid storage tank 110 decreases, the liquid level gradually decreases, and the liquid static pressure decreases. The headspace pressure Y needs to be increased. By increasing the headspace pressure Y in the liquid storage tank 110, the outlet pressure of the liquid storage tank 110 leading to the filling system 200 is kept unchanged.

[0071] A functional relationship is established between the headspace pressure in the liquid storage tank 110 and the weight of the liquid in the liquid storage tank 110. The required headspace pressure and the liquid weight are calculated as follows:

[0072] Y=aX 2 -bX+c

[0073] Y is the required headspace pressure; X is the weight of the liquid in the liquid storage tank; a / b / c is the normal coefficient; a / b / c is calculated and determined based on the height of the liquid storage tank, the height of the filling head, the density of the liquid to be filled, the fluidity of the liquid to be filled, the filling time, and the filling speed.

[0074] The pressure sensor 140 detects the real-time headspace pressure of the top space 111, and obtains the pressure difference to be adjusted as △Y based on the real-time headspace pressure Y' before adjustment by the pressure regulating device 130 and the required headspace pressure Y. The pressure regulating device 130 adjusts the headspace pressure according to the pressure difference to be adjusted △Y to make the headspace pressure equal to the required headspace pressure, so as to keep the outlet pressure of the liquid storage tank 110 unchanged.

[0075] S180, repeat step S160 until the weight of the liquid in the liquid storage tank 110 is less than the set minimum weight threshold, and then turn off the liquid filling device. In this embodiment, the minimum weight threshold of the liquid storage tank 110 is the state where the liquid storage tank 110 is empty.

[0076] Preferably, in step S160, the process of "determining the pressure difference to be adjusted and regulating the pressure by the pressure regulating device" is performed simultaneously with the process of "returning the filling head". Controlling the headspace pressure difference of the liquid storage tank 110 during the return of the filling head can accurately control the headspace pressure of the liquid storage tank 110 and precisely control the filling volume.

[0077] Example 3

[0078] This embodiment is basically the same as Embodiment 2, except that, in this embodiment, in the “determine the pressure difference to be adjusted” of step S160, “determine the pressure difference to be adjusted according to the required headspace pressure and the real-time headspace pressure”, it includes: setting a pressure difference threshold in the control system, comparing the pressure difference between the required headspace pressure and the real-time headspace pressure with the pressure difference threshold, thereby determining the pressure difference to be adjusted, when the required headspace pressure-real-time headspace pressure ≥ the pressure difference threshold, the pressure difference to be adjusted = the required headspace pressure-real-time headspace pressure. When the required headspace pressure-real-time headspace pressure < the pressure difference threshold, the pressure difference to be adjusted = 0.

[0079] Due to the large volume of the liquid storage tank, in one cycle, the liquid consumed in the filling process accounts for a very low proportion of the total volume of the liquid in the liquid storage tank. For example, for a 30,000L liquid storage tank, 10L is filled in each cycle, and the volume is only reduced by 0.03% each time. The liquid level changes little, and the static pressure generated by the liquid does not change much. Therefore, in the next filling cycle, the filling volume changes very little. Within the controllable range, when the pressure difference between the required headspace pressure and the real-time headspace pressure is less than the pressure difference threshold, it can be considered that there is no need to adjust the headspace pressure, and the pressure difference to be adjusted is determined to be 0. After several filling cycles, the headspace pressure needs to be adjusted only when the pressure difference between the required headspace pressure and the real-time headspace pressure is greater than or equal to the pressure difference threshold, and the pressure difference to be adjusted is determined to be = required headspace pressure - real-time headspace pressure. The liquid filling volume fluctuates less in one filling cycle or several consecutive filling cycles.

[0080] In the present invention, as the filling proceeds, the liquid level in the liquid storage tank gradually decreases, and the static pressure generated by the liquid decreases. A quadratic function relationship is established between the headspace pressure in the liquid storage tank and the weight of the liquid in the storage tank, so that the headspace pressure increases as the weight of the liquid storage tank decreases, and the liquid pressure leading to the filling system is kept unchanged, thereby controlling the flow rate to remain unchanged, and ultimately controlling the amount of liquid filled to remain unchanged.

[0081] Although the present invention has been described in detail above by means of general description, specific implementation methods and tests, it is obvious to those skilled in the art that some modifications or improvements may be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A liquid filling device, characterized in that: Including control system, liquid storage system and filling system; The liquid storage system comprises a liquid storage tank, a weighing device, a pressure regulating device and a pressure sensor; the liquid storage tank is used to hold the liquid to be filled and leave a head space; the weighing device is used to weigh the real-time liquid weight of the liquid storage tank; the pressure sensor is used to measure the real-time headspace pressure of the headspace; the pressure regulating device is connected to the headspace of the liquid storage tank and is used to adjust the headspace pressure of the liquid storage tank; The filling system comprises a filling head and a moving mechanism; the liquid storage tank is connected to the filling head through a discharge pipeline, and the moving mechanism is used to drive the filling head to move forward and reverse; The control system is respectively connected with the weighing device, the pressure sensor, the pressure regulating device and the filling system; The control system controls the pressure regulating device to adjust the headspace pressure according to the weight of the liquid, wherein the headspace pressure increases as the weight of the liquid in the liquid storage tank decreases.

2. The liquid filling equipment according to claim 1, characterized in that: The filling head comprises a liquid dispenser, a plurality of filling needles connected to the liquid dispenser, and a filling valve arranged on the filling needles, and the control system is connected to the filling valve.

3. The liquid filling equipment according to claim 2, characterized in that: The discharge pipeline is provided with a discharge valve, and the control system is connected with the filling valve.

4. The liquid filling equipment according to claim 1, characterized in that: The liquid storage tank is provided with a feed pipeline, the feed pipeline is provided with a feed valve, and the feed valve is connected to the control system.

5. The liquid filling equipment according to claim 4, characterized in that: The liquid storage tank is provided with an exhaust valve for exhausting the gas in the liquid storage tank.

6. The liquid filling equipment according to claim 1, characterized in that: The liquid storage tank is provided with a stirrer for stirring the liquid in the liquid storage tank.

7. A liquid filling method, using the liquid filling device according to any one of claims 1 to 6, characterized in that: The following steps are involved: S120, the liquid storage tank is filled with liquid, and after the liquid filling is completed, the liquid storage tank is sealed; S140, the control system obtains the initial liquid weight in the liquid storage tank measured by the weighing device and the initial headspace pressure measured by the pressure sensor, and controls the pressure regulating device to adjust the headspace pressure; S160, liquid filling, including: Filling head moves forward: the moving mechanism drives the filling head to move forward and move synchronously with the packaging container, the filling head is opened, and the filling head fills liquid into the packaging container; Filling head return: After filling is completed, the filling head is closed, and the moving mechanism drives the filling head to move in the reverse direction to the initial position; Determine the pressure difference to be adjusted: the control system obtains the real-time liquid weight of the liquid storage tank measured by the weighing device to calculate the corresponding required headspace pressure, the control system obtains the real-time headspace pressure measured by the pressure sensor, and determines the pressure difference to be adjusted according to the required headspace pressure and the real-time headspace pressure; Pressure regulation by pressure regulating device: Control the pressure regulating device to adjust the headspace pressure according to the pressure difference to be adjusted; S180, repeat step S160 until the liquid weight in the liquid storage tank is less than the set minimum weight threshold, and then turn off the liquid filling equipment.

8. The liquid filling equipment according to claim 7, characterized in that: The required headspace pressure and the real-time liquid weight are calculated as follows: Y=aX 2 -bX+c Where Y is the required headspace pressure; X is the weight of the liquid in the tank; a / b / c are the normal coefficients.

9. The liquid filling equipment according to claim 7, characterized in that: The process of "determining the pressure difference to be adjusted and adjusting the pressure by the pressure regulating device" in S160 is performed simultaneously with the process of "returning the filling head".

10. The liquid filling equipment according to claim 7, characterized in that: The step of determining the pressure difference to be adjusted according to the required headspace pressure and the real-time headspace pressure comprises: Pressure difference to be adjusted = required headspace pressure - real-time headspace pressure.

11. The liquid filling equipment according to claim 7, characterized in that: The step of determining the pressure difference to be adjusted according to the required headspace pressure and the real-time headspace pressure includes: setting a pressure difference threshold in the control system, When the required headspace pressure minus the real-time headspace pressure ≥ the pressure difference threshold, the pressure difference to be adjusted = the required headspace pressure minus the real-time headspace pressure; or When the required headspace pressure minus the real-time headspace pressure is less than the pressure difference threshold, the pressure difference to be adjusted = 0.

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