A method for controlling the filling pressure of a gas cylinder by a CNG filling machine

Abstract

The present invention relates to a method for precisely controlling the filling pressure of an on-vehicle gas cylinder by a CNG dispenser. By compensating the pressure of the filling pipeline of the dispenser, the corresponding relationship between the flow rate and pressure signals of the gas filled by the dispenser during the filling process and the pressure signal in the gas cylinder is obtained, and then the control of the pressure in the filling gas cylinder by the CNG dispenser is realized. The process includes: collecting the flow rate signal and pressure signal of the filling gas in the filling pipeline of the dispenser; collecting the pressure of the on-vehicle gas cylinder during the filling process by the dispenser; according to the filling gas flow rate signal V and the filling gas pressure signal P 管 calculate the pressure P of the on-vehicle gas cylinder to be filled 瓶 and the corresponding relationship with the filling gas flow rate signal V and the filling gas pressure signal P of the dispenser 管 ; the control module of the dispenser precisely controls the filling pressure of the on-vehicle gas cylinder according to the corresponding relationship between the filling gas flow rate signal and the filling gas pressure signal and the pressure of the on-vehicle gas cylinder to be filled.

Description

Technical Field

[0001] The invention relates to a method for accurately controlling the filling pressure of a vehicle-mounted gas cylinder by a CNG filling machine. Background Art

[0002] The filling pressure of CNG refueling vehicles is high and the filling speed is fast. The gas dispenser must accurately control the filling pressure to prevent over-pressure filling, which is dangerous and endangers the safety of drivers and passengers. At the same time, if the filling pressure cannot be filled to the fixed pressure, the volume of the gas cylinder will be wasted, the number of filling times of the vehicle will increase, the inconvenience will be caused to the driver, and the filling efficiency will be reduced.

[0003] Due to the limitations of current refueling vehicles and refueling conditions, there is no reliable and convenient data communication method between the gas dispenser and the on-board gas cylinder, and the actual on-board gas cylinder pressure cannot be directly obtained by the gas dispenser. Therefore, current gas dispensers all use the method of installing a pressure sensor inside the gas dispenser, and collect the pressure of the pressure sensor inside the gas dispenser as the pressure of the on-board gas cylinder. However, because there is a filling gun air pipe between the gas dispenser and the on-board gas cylinder, due to the fluctuation of the filling flow rate during the filling process, there is a huge error between the pressure inside the gas dispenser and the pressure of the on-board gas cylinder. The gas dispenser cannot accurately control the gas pressure filled into the gas cylinder.

[0004] Therefore, it is necessary to propose a control method to achieve accurate control of the filling pressure of the on-board gas cylinder by the CNG filling machine. Summary of the invention

[0005] In view of the shortcomings of the prior art (directly taking the collected internal pressure of the filling pipeline of the gas dispenser as the pressure of the on-board gas cylinder, which cannot truly reflect the pressure of the on-board gas cylinder and thus has a large error as a basis for control), the present invention proposes a method for controlling the filling pressure of the gas cylinder by a CNG gas dispenser. By performing error compensation on the pressure collected on the filling pipeline of the gas dispenser, the gas cylinder pressure that is as close to the actual one as possible is indirectly calculated, thereby performing accurate gas filling control.

[0006] The technical solution adopted by the present invention is:

[0007] A method for controlling the filling pressure of a gas cylinder by a CNG filling machine, the process comprising:

[0008] (1) The flow meter installed in the gas filling pipeline is used to collect the filling gas flow rate signal V in the gas filling machine pipeline;

[0009] (2) The pressure sensor installed in the gas filling pipeline collects the filling gas pressure signal P in the gas filling pipeline of the gas filling machine. 管 ;

[0010] (3) Collect the pressure P of the vehicle gas cylinder during the filling process of the gas dispenser 瓶 ;

[0011] (4) According to the filling gas flow rate signal V and the filling gas pressure signal P 管 The gas filling flow rate signal V and the filling gas pressure signal P of the gas filling machine are calculated by the following formula (1): 管 The pressure of the gas cylinder being filled is P 瓶 The corresponding relationship is stored in the storage unit of the gas dispenser control module;

[0012] P 瓶 =P 管 - (V-16)*100 / 24 ​​(1)

[0013] (5) When refueling, the refueling control module (controller) of the refueling machine calculates P using formula (1) 瓶 , according to P 瓶 Determine whether the vehicle gas cylinder is filled to the set pressure of 20MPa. 瓶 When the pressure is greater than or equal to the set pressure of 20MPa, close the high-pressure, medium-pressure and low-pressure solenoid valves to complete the filling.

[0014] When refueling starts, the refueling control module first opens the low-pressure solenoid valve and closes the medium-pressure solenoid valve and the high-pressure solenoid valve. The control module calculates the cylinder pressure P according to formula (1): 瓶 , and the pressure P in the gas filling machine pipeline 管 Compare. When P 瓶 Greater than or equal to P 管 When the low-pressure solenoid valve and the high-pressure solenoid valve are closed, the medium-pressure solenoid valve is opened. In this way, the pressure of the gas cylinder can be judged through customs clearance to select the appropriate pressure pipeline for rapid gas filling; the high-pressure CNG gas enters the gas dispenser from the check valve, and is filled into the vehicle-mounted gas cylinder through the flow meter, breakaway valve, high-pressure hose, and gas filling gun.

[0015] The filling control module of the gas dispenser collects the flow rate during the filling process through the flow meter, and collects the gas pressure inside the filling pipeline of the gas dispenser through the pressure sensor. Compare the collected pressure with the pressure displayed on the mechanical pressure gauge on the vehicle-mounted gas cylinder, and calculate the corresponding relationship between the pressure displayed on the mechanical pressure gauge of the vehicle-mounted gas cylinder and the pressure collected by the pressure sensor, the pressure of the vehicle-mounted gas cylinder, and the filling flow rate of the gas dispenser. And convert the corresponding relationship into a calculation formula and save it in the main board of the gas dispenser. The purpose of compensating the pressure sensor pressure collected by the gas dispenser according to the filling flow rate is achieved, so that the filling control module of the gas dispenser can accurately determine the pressure of the vehicle-mounted gas cylinder.

[0016] A pressure sensor is installed inside the gas filling pipeline of the gas filling machine, and can output a linear 4-20mA analog signal according to the pressure; a flow meter is installed inside the gas filling machine, and the flow meter can output a digital signal of the gas filling flow rate in real time;

[0017] High-pressure, medium-pressure and low-pressure solenoid valves are installed inside the gas dispenser, and the solenoid valves can be opened and closed according to the control signal;

[0018] A gas dispenser control module is installed inside the gas dispenser. During the filling process, the gas dispenser control module collects the filling flow rate V in the gas dispenser aisle through the flow meter, and converts the 4-20mA analog signal of the pressure sensor into a digital pressure signal P 管 .

[0019] The patent uses the two parameters V and P to realize the pressure P of the gas cylinder to be filled. 瓶 The pressure of the gas cylinder being filled on the vehicle is P 瓶 The calculation is as follows:

[0020] P 瓶 =P 管 - (V-16)*100 / 24

[0021] According to national standards, the maximum pressure for filling vehicle-mounted gas cylinders with a gas filling machine is 20MPa. Exceeding 20Mpa may be dangerous.

[0022] The operation result is converted into an electrical signal by the control circuit of the air receiving machine control module. 瓶 When the pressure is greater than or equal to 20MPa, the gas filling machine control module closes all electronic valves to complete the filling. The display module displays the filling volume and amount for fee settlement.

[0023] The gas filling machine control module consists of a power board, an intrinsically safe power supply circuit board, a metering collection and solenoid valve control main board, an IC card deduction and keypad, and a display screen; among them, the power board realizes the function of converting the input AC power into DC power and realizing isolation; the intrinsically safe circuit board realizes the intrinsic safety of the power supply, and supplies power to the metering data collection and solenoid valve control function module, the IC card deduction and keypad function module, and the display module; the metering data collection and solenoid valve control board realizes metering data collection to achieve metering, and at the same time controls the opening and closing of the corresponding solenoid valve according to the gas filling process; the IC card deduction and keypad realizes IC card reading and recognition, deduction after gas filling is completed, and is responsible for the human-computer interaction of the keypad; the display screen realizes the display of process data such as gas filling volume, gas filling amount, unit price, flow rate, pressure, etc. during the gas filling process.

[0024] The main functions of the metering data acquisition and solenoid valve control board:

[0025] (1) The metering acquisition and solenoid valve control mainboard is connected to an external flow meter, and the metering acquisition and solenoid valve control mainboard collects the flow rate, temperature and quality of the gas flowing through the gas filling machine pipeline during the gas filling process through the flow meter;

[0026] (2) The metering acquisition and solenoid valve control mainboard is connected to high, medium and low pressure solenoid valves. The metering acquisition and solenoid valve control mainboard controls the start and stop of gas filling through high, medium and low pressure solenoid valves;

[0027] (3) The metering collection and solenoid valve control main board is connected to an external pressure sensor. The metering collection and solenoid valve control main board collects the gas pressure in the gas filling machine pipeline during the filling process through the pressure sensor.

[0028] Beneficial effects of the invention:

[0029] 1. The method for controlling the filling pressure of the gas cylinder by the CNG filling machine of the present invention is to calculate the filling flow rate V and pressure of the filling machine and the pressure P of the gas cylinder on the vehicle to be filled during the filling process by performing error compensation on the pressure collected by the pressure sensor on the filling machine. 瓶 The corresponding relationship between the CNG filling machine and the vehicle-mounted gas cylinder pressure P is realized. 瓶 Accurate control. The cylinder pressure P is calculated by formula (1): 瓶 Infinitely close to the actual pressure of the gas cylinder.

[0030] 2. The method of the CNG filling machine of the present invention controls the filling pressure of the gas cylinder by comparing it with the corresponding intake pipe pressure and selecting the pipe with appropriate pressure for filling, so as to achieve the purpose of rapid filling. At the beginning of filling, the low-pressure solenoid valve is opened first, and the medium-pressure solenoid valve and the high-pressure solenoid valve are closed. The filling machine control module calculates the gas cylinder pressure P according to formula (1). 瓶 , and the pressure P in the gas filling machine pipeline 管 Compare. When P 瓶 Greater than or equal to P 管 When the gas cylinder is in the state of being filled, close the low-pressure solenoid valve and the high-pressure solenoid valve, and open the medium-pressure solenoid valve. The pressure of the gas cylinder can be judged through customs clearance, and the appropriate pressure pipeline can be selected for rapid gas filling.

[0031] 3. The method for controlling the filling pressure of a gas cylinder by a CNG filling machine of the present invention, wherein the filling machine control module controls the filling pressure of the gas cylinder according to the gas cylinder pressure P calculated by formula (1). 瓶 , accurately control the filling pressure of the gas cylinder, automatically control the filling, and improve the filling efficiency. It can effectively prevent the gas cylinder from being underfilled or the filling pressure exceeding the limit pressure of 20MPa. 瓶 When it is greater than or equal to 20MPa, the on-board gas cylinder is considered to be fully filled and filling needs to be stopped. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The figure shows the process flow diagram of CNG filling machine filling process;

[0033] Figure 2Shown is the functional block diagram of the gas dispenser control module. DETAILED DESCRIPTION

[0034] In order to make the technical concept and advantages of the invention more clearly understood, the technical solution of the invention is further described in detail below in conjunction with the accompanying drawings. It should be understood that the following embodiments are only used to explain and illustrate the preferred implementation methods of the invention and should not constitute a limitation on the scope of the patent protection required by the invention.

[0035] Example 1

[0036] See also Figure 1 , is a process flow chart of the CNG filling process of the present invention.

[0037] The method for controlling the filling pressure of a gas cylinder by a CNG gas dispenser of the present invention performs error compensation on the pressure collected by a pressure sensor on the gas dispenser, obtains the corresponding relationship between the flow rate and pressure signal of the gas filled by the gas dispenser during the filling process and the pressure signal in the gas cylinder, and then realizes the control of the pressure in the filling gas cylinder by the CNG gas dispenser, and the process includes:

[0038] 1) Collect the filling gas flow rate signal V in the filling pipeline of the gas filling machine;

[0039] 2) Collect the filling gas pressure signal P in the filling pipeline of the gas filling machine 管 ;

[0040] 3) Collect the pressure P of the vehicle gas cylinder during the filling process of the gas dispenser 瓶 ;

[0041] 4) According to the filling gas flow rate signal V and the filling gas pressure signal P 管 , the pressure P of the gas cylinder to be filled is calculated by the following formula (1) 瓶 The gas filling machine fills the gas flow rate signal V and the filling gas pressure signal P 管 The corresponding relationship:

[0042] P 瓶 =P 管 -(V-16)*100 / 24 ​​(1)

[0043] 5) The gas filling machine control module calculates the filling gas flow rate signal V and the filling gas pressure signal P according to the error compensation calculated in step 4). 管 The pressure of the gas cylinder being filled is P 瓶 The corresponding relationship is used to control the filling pressure of the vehicle-mounted gas cylinder during the filling process of the gas dispenser.

[0044] Example 2

[0045] The method for controlling the filling pressure of the gas cylinder by the CNG filling machine of this embodiment is different from that of the first embodiment in that, further, specifically, the filling pressure upper limit is set by the filling machine control module, and when the filling pressure upper limit is set according to the filling gas flow rate signal V and the filling gas pressure signal P 管 Calculated vehicle gas cylinder pressure P 瓶 When the pressure is greater than or equal to 20MPa, close the high-pressure, medium-pressure and low-pressure solenoid valves to complete the filling.

[0046] Example 3

[0047] The method for controlling the filling pressure of the gas cylinder by the CNG filling machine of this embodiment is different from that of Embodiments 1 and 2 in that the maximum fixed pressure of the low-pressure air intake pipeline is 19 MPa, the maximum fixed pressure of the medium-pressure air intake pipeline is 20 MPa, and the maximum fixed pressure of the high-pressure air intake pipeline is 21 MPa. At the beginning of filling, the filling machine control module calculates the vehicle-mounted gas cylinder pressure P according to formula (1). 瓶 Compared with the pressure of the three air intake pipes, the selected pressure is higher than the vehicle gas cylinder pressure P 瓶 And the closest pipeline, open the corresponding pipeline to start filling. Quick filling. When the vehicle gas cylinder pressure P 瓶 When the pressure is equal to the current pipeline pressure, close the current pipeline solenoid valve and open the higher pressure pipeline to start gas filling.

[0048] The current conventional control method is to open the low-pressure pipeline first to start filling gas at the beginning of filling gas. If the gas flow rate signal V filled through the low-pressure pipeline is less than a certain set value. Then switch to the medium-pressure pipeline to start filling. If the gas flow rate signal V filled through the medium-pressure pipeline is less than a certain set value. Then switch to the high-pressure pipeline to start filling. If the gas flow rate signal V filled through the high-pressure pipeline is less than a certain set value, it is considered that the pressure filling of the vehicle-mounted gas cylinder is completed and the filling of gas is ended. During the filling process of this method, the low, medium and high pipelines must be opened in sequence to know which pipeline to select for filling gas. It is impossible to quickly select the appropriate pipeline for filling gas, and the filling process is time-consuming. The present invention realizes rapid filling of gas by judging the pressure of the gas cylinder and selecting the appropriate pressure pipeline.

[0049] Example 4

[0050] See also Figure 1 , Figure 2 The method for controlling the filling pressure of the gas cylinder by the CNG filling machine of the present invention and the method for compensating the error of the pressure collected by the pressure sensor on the filling machine are as follows:

[0051] (1) A pressure sensor is installed inside the gas dispenser, and the sensor outputs a linear 4-20mA analog signal according to the pressure;

[0052] (2) A flow meter is installed inside the gas dispenser, which can output a digital signal of the gas flow rate in real time;

[0053] (3) The gas dispenser is equipped with high-pressure, medium-pressure and low-pressure solenoid valves, which can be opened and closed according to the control signal;

[0054] (4) A gas filling machine control module is installed inside the gas filling machine. During the filling process, the gas filling machine control module collects the filling flow rate V in the gas filling machine aisle through the flow meter, and converts the 4-20mA analog signal of the pressure sensor into a digital pressure signal P 管 The patent application of this invention uses the two parameters V and P to realize the pressure P of the gas cylinder to be filled. 瓶 The pressure of the gas cylinder being filled on the vehicle is P 瓶 The calculation is as follows:

[0055] P 瓶 =P 管 - (V-16)*100 / 24

[0056] (5) The operation results must also be converted into electrical signals by the control circuit of the air receiving machine control module, P 瓶 When the pressure is greater than or equal to 20MPa, the air receiving machine control module closes all electronic valves to complete the filling, and displays the filling volume and amount for fee settlement.

[0057] See also Figure 1 , high-pressure CNG gas enters the gas dispenser from the check valve 5, and is filled into the vehicle-mounted gas cylinder through the flow meter 8, the break valve 9, the high-pressure hose 10, and the gas gun 11. The control module of the gas dispenser 12 collects the flow rate during the filling process through the flow meter 8, and collects the gas pressure inside the gas dispenser through the pressure sensor 6. Compare the collected pressure with the pressure displayed by the mechanical pressure gauge 14 on the vehicle-mounted gas cylinder, and calculate the corresponding relationship between the pressure displayed by the mechanical pressure gauge 14 of the vehicle-mounted gas cylinder and the pressure collected by the pressure sensor 6, the pressure of the vehicle-mounted gas cylinder, and the filling flow rate of the gas dispenser. And convert the corresponding relationship into a calculation formula and save it in the main board of the gas dispenser. The purpose of compensating the pressure sensor pressure collected by the gas dispenser according to the filling flow rate is achieved, so that the control module of the gas dispenser 12 can accurately determine the pressure of the vehicle-mounted gas cylinder.

[0058] See also Figure 2 The gas dispenser control module consists of a power supply board 1, an intrinsically safe power supply circuit board 2, a metering acquisition and solenoid valve control main board 3, an IC card deduction and keypad 4, and a display screen 5; among them,

[0059] 1. The power board converts the input AC power into DC power and achieves isolation;

[0060] 2. The intrinsically safe circuit board realizes the intrinsic safety of the power supply, and supplies power to the metering data acquisition and solenoid valve control function module, IC card deduction and button function module, and display module;

[0061] 3. Metering data acquisition and solenoid valve control board realizes metering data acquisition and metering, and controls the opening and closing of the corresponding solenoid valve according to the gas filling process;

[0062] 4. IC card deduction and keypad realize IC card reading and recognition, deduction after gas filling is completed, and is responsible for human-computer interaction of keypad;

[0063] 5. Display screen, which can display the gas volume, gas amount, unit price, flow rate, pressure and other process data during the gas filling process.

[0064] 6. Main functions of metering data acquisition and solenoid valve control board:

[0065] (1) The metering acquisition and solenoid valve control mainboard is connected to an external flow meter, and the metering acquisition and solenoid valve control mainboard collects the flow rate, temperature and quality of the gas flowing through the gas filling machine pipeline during the gas filling process through the flow meter;

[0066] (2) The metering acquisition and solenoid valve control mainboard is connected to high, medium and low pressure solenoid valves. The metering acquisition and solenoid valve control mainboard controls the start and stop of gas filling through the high, medium and low pressure solenoid valves;

[0067] (3) The metering collection and solenoid valve control main board is connected to an external pressure sensor. The metering collection and solenoid valve control main board collects the gas pressure in the gas filling machine pipeline during the filling process through the pressure sensor.

[0068] The prior art directly uses the collected internal pressure of the filling pipe of the gas dispenser as the pressure of the vehicle-mounted gas cylinder as the basis for control, which has a large error and cannot truly reflect the pressure of the vehicle-mounted gas cylinder. The present invention compensates for the error of the collected pressure on the filling pipe of the gas dispenser and indirectly obtains the gas cylinder pressure as close to the real one as possible through calculation, thereby achieving the purpose of accurately identifying the pressure of the vehicle-mounted gas cylinder and then performing gas filling control, making the control more accurate.

[0069] The above description is only a preferred embodiment of the present invention and does not constitute a limitation of the present invention. Under the guidance of the prior art, those skilled in the art can make other modifications to the implementation of the present invention without creative work. Any modification made within the spirit and principle of the present invention or simple replacement or equivalent substitution using conventional technical means in the field should be included in the protection scope of the present invention.

Claims

1. A method for controlling the filling pressure of a gas cylinder by a CNG filling machine, characterized in that: By performing error compensation on the pressure collected by the pressure sensor on the gas dispenser, the corresponding relationship between the flow rate and pressure signal of the gas filled by the gas dispenser and the pressure signal in the gas cylinder is obtained during the filling process, thereby realizing the control of the pressure in the filling cylinder by the CNG gas dispenser. The process includes: 1) Collect the filling gas flow rate signal V in the filling pipeline of the gas filling machine; 2) Collect the filling gas pressure signal P in the filling pipeline of the gas filling machine 管 ; 3) Collect the pressure P of the vehicle gas cylinder during the filling process of the gas dispenser 瓶 ; 4) According to the filling gas flow rate signal V and the filling gas pressure signal P 管 , the pressure P of the gas cylinder to be filled is calculated by the following formula (1) 瓶 The gas filling machine fills the gas flow rate signal V and the filling gas pressure signal P 管 The corresponding relationship: P 瓶 =P 管 -(V-16)*100 / 24 (1) 5) The gas filling machine control module calculates the filling gas flow rate signal V and the filling gas pressure signal P according to the error compensation calculated in step 4). 管 The pressure of the gas cylinder being filled is P 瓶 The corresponding relationship between the filling pressure of the vehicle-mounted gas cylinder can be controlled during the filling process of the gas dispenser; The gas filling machine control module sets the upper limit of the filling pressure. When the filling gas flow rate signal V and the filling gas pressure signal P are 管 Calculated vehicle gas cylinder pressure P 瓶 When the pressure is greater than or equal to 20MPa, close the high-pressure, medium-pressure and low-pressure solenoid valves to complete the filling.

2. The method for controlling the filling pressure of a gas cylinder by a CNG filling machine according to claim 1, characterized in that: The maximum fixed pressure of the low-pressure air intake pipe is 19 MPa, the maximum fixed pressure of the medium-pressure air intake pipe is 20 MPa, and the maximum fixed pressure of the high-pressure air intake pipe is 21 MPa. At the beginning of refueling, the control module of the gas dispenser calculates the vehicle gas cylinder pressure P according to the formula (1). 瓶 , compared with the pressure of the three intake pipes, the selected pressure is higher than the vehicle gas cylinder pressure P 瓶 And the closest pipeline, open the corresponding pipeline to start filling, and quickly fill the gas; when the vehicle gas cylinder pressure P 瓶 When it is equal to the current pipeline pressure, close the current pipeline solenoid valve; Open the higher pressure line and start filling.

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