A gas fuel metering valve and its flow control method

Abstract

The present invention discloses a gas fuel metering valve, which includes a gas inlet pipe, a valve seat and a gas outlet pipe. The valve seat has a cavity with an air inlet and an air outlet. A gasket is installed in the cavity, and the outer wall of the gasket fits the inner wall of the cavity. The air inlet is communicated with the gas inlet pipe, and the air outlet is communicated with the gas outlet pipe. A driving motor is installed on the valve seat, and a driving gear is fixed on the output shaft of the driving motor. The driving gear cooperates with a valve rod to drive the valve rod to move up and down. The valve rod is located in the cavity, and a fuel valve is installed at the lower end of the valve rod. The structure of the fuel valve is adapted to the structure of the gasket to control the conduction and truncation of the cavity. A first temperature sensor and a first pressure sensor are arranged on the gas inlet pipe, a second temperature sensor and a second pressure sensor are arranged on the gas outlet pipe, and a lift position sensor is installed on the valve seat to detect the position of the valve rod. The present invention can achieve adaptive control of the fuel quantity of the engine.

Description

Technical Field

[0001] The present invention relates to a gas fuel metering valve and its flow control method, belonging to the technical field of the fuel supply system of gas fuel engines. Background Art

[0002] Currently, the flow control of the fuel supply system of gas fuel engines mainly uses gas nozzles, and the performance of the nozzles directly affects the precise control of engine fuel. At present, domestic gas nozzles are mainly imported from foreign products, and the poor stain resistance and durability of gas nozzles have always been a major problem in the gas system. Moreover, the nozzle must meet a certain injection pressure to open, making it difficult to apply to low-pressure gas supply systems. In this context, the present invention relates to a brand-new continuous gas fuel metering valve, which has a unique structural design, high control accuracy, and breaks the monopoly of foreign similar products in internal combustion engines. It not only solves the problem of poor stain resistance and durability of gas nozzles, but also adopts continuous flow control to reduce pressure fluctuations. It can also use a single product to cover the gas systems of engines with various displacements. At the same time, its extended products can also be applied to gas systems such as mining machinery and turbines.

[0003] Taking a natural gas engine as an example, the main component of natural gas is methane. In addition, it also contains hydrocarbon gases such as ethane, propane, and butane, as well as non-hydrocarbon gases such as nitrogen, CO22, and H2S. Generally, the methane content in gas reservoir natural gas is above 90%. The methane content in associated gas from oilfields accounts for 65% - 80%. The composition of natural gas varies greatly in different regions, resulting in a large difference in the calorific value of the fuel. The existing fuel control systems mainly target the current fuel type, calculate the fuel quantity based on the air quantity and the target air-fuel ratio, and adjust the fuel quantity through the method of air-fuel ratio correction. When the fuel composition varies greatly, it is difficult to achieve an ideal air-fuel ratio control effect. There is often a large deviation between the actual air-fuel ratio and the target value. Summary of the Invention

[0004] The purpose of the present invention is to provide a gas fuel metering valve that precisely controls the lift of the valve stem through a DC motor and a position sensor. The gear / valve stem structure has a micron-level clearance fit, which can effectively seal the gas. At the same time, when the pressures at the inlet and outlet ends satisfy the critical pressure difference and the input fuel temperature and pressure are stable, the lift of the valve stem and the flow rate satisfy a linear relationship. By collecting the temperature, pressure, inlet and outlet pressure ratio, and valve stem lift (i.e., the flow area) at the inlet and exhaust ends, the current flow rate is accurately calculated to achieve adaptive control of the engine fuel quantity.

[0005] To solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A gas fuel metering valve includes a gas inlet pipe, a valve seat, and a gas outlet pipe. The valve seat has a cavity with an air inlet and an air outlet. A gasket is installed in the cavity, and the outer wall of the gasket fits against the inner wall of the cavity. The air inlet is connected to the gas inlet pipe, and the air outlet is connected to the gas outlet pipe. A driving motor is installed on the valve seat, and a driving gear is fixed on the output shaft of the driving motor. The driving gear cooperates with a valve rod to drive the valve rod to move up and down. The valve rod is located in the cavity, and a fuel valve is installed at the lower end of the valve rod. The structure of the fuel valve is adapted to the structure of the gasket to control the conduction and cutoff of the cavity. A first temperature sensor and a first pressure sensor are provided on the gas inlet pipe, a second temperature sensor and a second pressure sensor are provided on the gas outlet pipe, and a lift position sensor is installed on the valve seat to detect the position of the valve rod.

[0007] In the aforementioned gas fuel metering valve, the cavity is composed of a first horizontal section, a vertical section, and a second horizontal section that are connected in sequence. The first horizontal section is connected to the gas inlet pipe, and the second horizontal section is connected to the gas outlet pipe. The gasket is located in the vertical section, and a clamping groove is provided on the valve seat of the vertical section. The gasket is fixed in the clamping groove.

[0008] The control method of the above-mentioned gas fuel metering valve adopts the following method to control the gas output rate of the gas outlet pipe:

[0009] Detect the air pressure P1 in the gas inlet pipe through the first pressure sensor, detect the air pressure P2 in the gas outlet pipe through the second pressure sensor, and detect the temperature T0 in the gas outlet pipe through the second temperature sensor;

[0010] Calculate the gas flow through the following formula,

[0011] ;

[0012] where Aeff represents the effective flow area of the gas, which has a linear relationship with the valve rod lift; Mdot represents the gas flow; C1 represents an empirical parameter, C2 represents an empirical parameter, and C3 represents an empirical parameter;

[0013] Determine the position where the valve rod needs to be according to Aeff, and control the driving motor to drive the valve rod to move to the specified position, thereby controlling the gas flow of the gas outlet pipe.

[0014] Compared with the prior art, the present invention precisely controls the lift of the valve stem through a DC motor and a position sensor. The gear / valve stem structure has a micron-level mating clearance, which can effectively seal the gas. Meanwhile, when the pressures at the intake end and the outlet end satisfy the critical pressure difference and the temperature and pressure of the input fuel are stable, the lift of the valve stem and the flow rate satisfy a linear relationship. By collecting the temperature, pressure, inlet and outlet pressure ratio, and valve stem lift (i.e., the flow area) at the intake and exhaust ends, the current flow rate is accurately calculated to achieve adaptive control of the fuel quantity of the engine. This patent has the following advantages:

[0015] 1. The lift of the valve stem has a linear relationship with the effective flow area of the gaseous fuel. The flow area can be increased proportionally by adjusting the size to adapt to engines with different displacements;

[0016] 2. The flow area of the gaseous fuel far exceeds the spray holes of the nozzle, which is beneficial to the discharge of gas impurities. The process is simple, it can be cleaned, and it has good stain resistance;

[0017] 3. In the continuous flow fuel supply mode, the temperature and pressure fluctuations of the gaseous fuel during use are small, and the air-fuel ratio of the engine is stable, which is more conducive to reducing pollutant emissions;

[0018] 4. For low-pressure pipeline gas, a pressurizing device is not required. The system has a compact structure, low cost, and high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic structural diagram of an embodiment of the present invention;

[0020] Figure 2 is a schematic internal structural diagram of an embodiment of the present invention.

[0021] Reference numerals: 1 - gas inlet pipe, 2 - first horizontal section, 3 - intake port, 4 - gasket, 5 - cavity, 6 - valve seat, 7 - vertical section, 8 - driving gear, 9 - lift position sensor, 10 - driving motor, 11 - second horizontal section, 12 - fuel valve, 13 - valve stem, 14 - clamping groove, 15 - outlet port, 16 - second pressure sensor, 17 - gas outlet pipe, 18 - first pressure sensor.

[0022] The present invention will be further described below with reference to the drawings and specific embodiments. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] Embodiment 1 of the present invention: A gas fuel metering valve includes a gas inlet pipe 1, a valve seat 6, and a gas outlet pipe 17. The valve seat 6 has a cavity 5. The cavity 5 has an air inlet 3 and an air outlet 15. A gasket 4 is installed in the cavity 5, and the outer wall of the gasket 4 fits against the inner wall of the cavity 5; the air inlet 3 is connected to the gas inlet pipe 1, and the air outlet 15 is connected to the gas outlet pipe 17; a driving motor 10 is installed on the valve seat 6. A driving gear 8 is fixed on the output shaft of the driving motor 10. The driving gear 8 cooperates with a valve rod 13 to drive the valve rod 13 to move up and down. The structures of the driving gear 8 and the valve rod 13 belong to the prior art and will not be elaborated here; the valve rod 13 is located in the cavity 5, and a fuel valve 12 is installed at the lower end of the valve rod 13. The structure of the fuel valve 12 is adapted to the structure of the gasket 4 for controlling the conduction and cutoff of the cavity 5; a first temperature sensor and a first pressure sensor 18 are provided on the gas inlet pipe 1, a second temperature sensor and a second pressure sensor 16 are provided on the gas outlet pipe 17, and a lift position sensor 9 is installed on the valve seat 6. The lift position sensor 9 is used to detect the position of the valve rod 13. A rack mechanism is adopted between the valve rod 13 and the driving gear 8 to convert the rotating mechanism of the motor into a linear motion of the valve rod to accurately control the lift of the valve rod.

[0024] Embodiment 2: A gas fuel metering valve includes a gas inlet pipe 1, a valve seat 6, and a gas outlet pipe 17. The valve seat 6 has a cavity 5. The cavity 5 has an air inlet 3 and an air outlet 15. A gasket 4 is installed in the cavity 5, and the outer wall of the gasket 4 fits against the inner wall of the cavity 5; the air inlet 3 is connected to the gas inlet pipe 1, and the air outlet 15 is connected to the gas outlet pipe 17; a driving motor 10 is installed on the valve seat 6. A driving gear 8 is fixed on the output shaft of the driving motor 10. The driving gear 8 cooperates with a valve rod 13 to drive the valve rod 13 to move up and down. The structures of the driving gear 8 and the valve rod 13 belong to the prior art and will not be elaborated here; the valve rod 13 is located in the cavity 5, and a fuel valve 12 is installed at the lower end of the valve rod 13. The structure of the fuel valve 12 is adapted to the structure of the gasket 4 for controlling the conduction and cutoff of the cavity 5; a first temperature sensor and a first pressure sensor 18 are provided on the gas inlet pipe 1, a second temperature sensor and a second pressure sensor 16 are provided on the gas outlet pipe 17, and a lift position sensor 9 is installed on the valve seat 6. The lift position sensor 9 is used to detect the position of the valve rod 13. A rack mechanism is adopted between the valve rod 13 and the driving gear 8 to convert the rotating mechanism of the motor into a linear motion of the valve rod to accurately control the lift of the valve rod.

[0025] The cavity 5 is composed of a first horizontal section 2, a vertical section 7, and a second horizontal section 11 that are connected in sequence. The first horizontal section 2 is connected to the gas inlet pipe 1, and the second horizontal section 11 is connected to the gas outlet pipe 17; the gasket 4 is located in the vertical section 7, and a clamping groove 14 is provided on the valve seat 6 of the vertical section 7, and the gasket 4 is fixed in the clamping groove 14.

[0026] A control method for a gas fuel metering valve described in the above embodiments controls the gas output rate of the gas outlet pipe 17 by the following method:

[0027] Detect the air pressure P1 in the gas inlet pipe 1 through the first pressure sensor 18, detect the air pressure P2 in the gas outlet pipe 17 through the second pressure sensor 16, and detect the temperature T0 in the gas outlet pipe 17 through the second temperature sensor;

[0028] Calculate the gas flow rate through the following formula,

[0029] ;

[0030] wherein Aeff represents the effective flow area of the gas, which is linearly related to the lift of the valve stem 13; Mdot represents the gas flow rate; C1 represents an empirical parameter, C2 represents an empirical parameter, and C3 represents an empirical parameter; the above formula is derived according to the Bernoulli equation;

[0031] Determine the position where the valve stem 13 needs to be according to Aeff, control the drive motor 10 to drive the valve stem 13 to move to the specified position, and then control the gas flow rate of the gas outlet pipe 17. Specifically, if the gas flow rate does not reach the specified value, drive the fuel valve 12 away from the card slot 14 through the drive motor 10 and the valve stem 13 to increase the gas flow area and increase the flow rate; if the gas flow rate exceeds the specified value, drive the fuel valve 12 close to the card slot 14 through the drive motor 10 and the valve stem 13 to reduce the gas flow area and reduce the flow rate.

Claims

1. A control method for a gas fuel metering valve. The gas fuel metering valve includes a gas inlet pipe (1), a valve seat (6), and a gas outlet pipe (17). The valve seat (6) has a cavity (5). The cavity (5) has an air inlet (3) and an air outlet (15). A gasket (4) is installed in the cavity (5), and the outer wall of the gasket (4) fits against the inner wall of the cavity (5). The air inlet (3) is communicated with the gas inlet pipe (1), and the air outlet (15) is communicated with the gas outlet pipe (17). A driving motor (10) is installed on the valve seat (6). A driving gear (8) is fixed on the output shaft of the driving motor (10). The driving gear (8) cooperates with a valve rod (13) to drive the valve rod (13) to move up and down. The valve rod (13) is located in the cavity (5). A fuel valve (12) is installed at the lower end of the valve rod (13). The structure of the fuel valve (12) is adapted to the structure of the gasket (4) and is used to control the conduction and cutoff of the cavity (5). A first temperature sensor and a first pressure sensor (18) are provided on the gas inlet pipe (1). A second temperature sensor and a second pressure sensor (16) are provided on the gas outlet pipe (17). A lift position sensor (9) is installed on the valve seat (6), and the lift position sensor (9) is used to detect the position of the valve rod (13). It is characterized in that The following method is used to control the gas output rate of the gas outlet pipe (17): The air pressure P1 in the gas inlet pipe (1) is detected by the first pressure sensor (18), the air pressure P2 in the gas outlet pipe (17) is detected by the second pressure sensor (16), and the temperature T0 in the gas outlet pipe (17) is detected by the second temperature sensor. The gas flow rate is calculated by the following formula ； where Aeff represents the effective flow area of the gas, which has a linear relationship with the lift of the valve rod (13); Mdot represents the gas flow rate; C1 represents an empirical parameter, C2 represents an empirical parameter, and C3 represents an empirical parameter. According to Aeff, the position that the valve rod (13) needs to be in is determined. By controlling the driving motor (10) to drive the valve rod (13) to move to the specified position, the gas flow rate of the gas outlet pipe (17) is further controlled.

2. The control method of a gas fuel metering valve according to claim 1, characterized in that, The cavity (5) is composed of a first horizontal section (2), a vertical section (7), and a second horizontal section (11) that are connected in sequence. The first horizontal section (2) is communicated with the gas inlet pipe (1), and the second horizontal section (11) is communicated with the gas outlet pipe (17). The gasket (4) is located in the vertical section (7). A clamping groove (14) is provided on the valve seat (6) of the vertical section (7), and the gasket (4) is fixed in the clamping groove (14).

Images