JP3490237B2 - Pilot gas pressure control device and pressure control method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION Generally, a lean burn gas engine is composed of a main combustion chamber and a precombustion chamber. The pre-combustion chamber acts as an ignition source for the lean mixture introduced into the main combustion chamber. Pilot gas is supplied to this pre-combustion chamber,
The present invention relates to a pressure adjusting mechanism for a pilot gas supplied to a pre-combustion chamber and a method thereof.

[0002]

2. Description of the Related Art FIG. 9 shows a pilot gas pressure control system in a conventional lean burn gas engine. Cylinder 1
The amount of pilot gas supplied to the pre-combustion chamber 2 inside must be controlled to be an appropriate value over the entire load range of the gas engine in order to ensure stable combustion. This control is performed using the pressure difference ΔP between the gas pressure in the pilot main pipe 3 and the air supply pressure in the air supply pipe 4 as an index, and is realized by adjusting the pressure regulator 5.

As shown in FIG. 10, a conventional pressure regulator 5 includes a pressure adjusting screw 7 movably screwed into a valve box 6 and a valve body which is provided in the valve box 6 to open and close a gas passage. 8 and a pressure adjusting spring 10 that operates the valve body 8 and is provided in the valve box 6 via the spring receiver 9 on the pressure adjusting screw 7. The discharge pressure of the pressure regulator 5 is set by the pressure adjusting spring 10 by manually adjusting the pressure adjusting screw 7. In this structure, the pressure adjusting screw 7 is the lock nut 11
Since the discharge pressure once set is fixed, the discharge pressure once set continues to be fixed until readjusted.

[0004]

According to the conventional pilot gas pressure control device for the lean burn gas engine, it is impossible to adjust the differential pressure .DELTA.P to the optimum value according to the load factor during operation of the gas engine. There was a problem. Therefore, when the load is high, the fluctuation in combustion is small, and the combustion balance between the cylinders is relatively good.

An object of the present invention is to provide an apparatus and method for controlling the pilot gas pressure so that the differential pressure ΔP becomes an optimum value in accordance with the operating state of the gas engine and a favorable operation is performed. There is.

[0006]

According to a first aspect of the present invention, there is provided a pilot gas pressure control device for controlling the pressure of pilot gas supplied to a pre-combustion chamber constituting a combustion chamber of a gas engine. In the control device, the pressure of pilot gas supplied to the pre-combustion chamber is adjusted by adjusting the opening degree with a stepping motor connected only to the pilot gas main pipe connected to the pre-combustion chamber and connected to a pressure adjusting screw. Pressure regulator, operating state detecting means for detecting an operating state of the gas engine, differential pressure detecting means for detecting a differential pressure between the pilot gas pressure and the supply pressure in the gas engine, and the gas engine The operating state of the gas engine, which has data relating to the optimum value of the differential pressure corresponding to the operating state, and which is detected by the operating state detecting means. And the optimum value of definitive the differential pressure, a deviation between the actual differential pressure the differential pressure detection means detects, and a control means for controlling the pressure regulator based on the deviation.

A pilot gas pressure control method according to a second aspect of the present invention is a pilot gas pressure control method for controlling the pressure of pilot gas supplied to a pre-combustion chamber forming a combustion chamber of a gas engine. Detecting the operating state of the engine, from the data regarding the optimum value of the differential pressure between the pressure of the pilot gas and the supply pressure corresponding to the operating state of the gas engine, from the data of the differential pressure in the detected operating state of the gas engine Obtaining the optimum value, detecting the actual differential pressure in the gas engine, determining the deviation between the actual differential pressure and the optimum value of the differential pressure in the actual operating state, the pilot gas connected to the pre-combustion chamber A stepping motor that is connected only to the main pipe and adjusts the opening of a pressure regulator that adjusts the pressure of pilot gas supplied to the pre-combustion chamber Controlled on the basis of the deviation, control the pressure of the pilot gas.

A pilot gas pressure control device according to a third aspect is the pilot gas pressure control device according to the first aspect, wherein the operating state detecting means detects a rotational speed of the gas engine. It is characterized by being a means.

According to a fourth aspect of the present invention, there is provided a pilot gas pressure control apparatus according to the first aspect, wherein the operating state detecting means is load detecting means for detecting a load of the gas engine. It is characterized by being.

According to a fifth aspect of the present invention, there is provided a pilot gas pressure control apparatus according to the first aspect, wherein the differential pressure detecting means is a strain gauge.

A pilot gas pressure control device according to a sixth aspect is the pilot gas pressure control device according to the first aspect, characterized in that the differential pressure detecting means is constituted by a piezo element.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION One example of an embodiment of the present invention is shown in FIG.
~ It demonstrates with reference to FIG. FIG. 1 shows a lean burn gas engine 13 (gas engine, also abbreviated as engine) having a pilot gas pressure controller 12. The plurality of main combustion chambers 14 of the gas engine 13 are each connected to a fuel gas main pipe 16 via a balancing valve 15. The fuel gas main pipe 16 is controlled by the governor 17.
The gas pressure control valve 18 and the second gas pressure control valve 19 are connected to the supply source. In addition, each main combustion chamber 14
An air supply pipe 4 is connected to the via a branch pipe.

The combustion chamber of the gas engine comprises a main combustion chamber 14 and a pre-combustion chamber 2. Here, the pre-combustion chamber is provided in the cylinder head and communicates with the main combustion chamber through a plurality of communication holes. Each pre-combustion chamber 2 is connected to a pilot gas main pipe 3, respectively. The pilot gas main pipe 3 is connected to the fuel gas main pipe 16 via two pressure regulators 20, 20 connected in series, and is connected to a common supply source with the fuel gas.

FIG. 2 is a diagram showing the pressure regulator. The basic structure of the valve is the same as that of the conventional pressure regulator 5 shown in FIG. The drive shaft of the stepping motor 23 is connected to the upper end of the pressure adjusting screw 7 that adjusts the opening of the gas flow path via a highly rigid rubber coupling 21 and a joint collar 22. The stepping motor 23 has a drive torque of 20 kgf · cm and a minimum of 0.
It has a characteristic of 6 deg / step. The opening degree of the gas flow path of the pressure regulator 20 can be adjusted by giving an appropriate control signal to the stepping motor 23, whereby the pressure of the pilot gas supplied to the pre-combustion chamber 2 can be controlled.

The pilot gas pressure control device 12 of this embodiment shown in FIG. 3 is intended to optimally control the pressure of the pilot gas supplied to the pre-combustion chamber 2 in accordance with the operating state of the gas engine 13. , Stepping motor 23
It has the pressure regulator 20 for adjusting the opening degree and the control means 30 for remotely supplying an electric signal (control signal, control value) to the stepping motor 23.

The control means 30 controls the pressure regulator 20 using the pressure difference ΔP between the pilot gas pressure and the supply pressure as an index. Therefore, the control means 30 holds the data regarding the optimum value of the differential pressure ΔP corresponding to the operating state of the gas engine 13 in the storage means. This data was obtained in advance by a combustion test, and is 25% (1% for every 200 revolutions in the rated load range from engine start).
3%) shows the optimum differential pressure ΔP measured for each load factor.

[0017]

[Table 1]

Then, the control means 30 detects the operating state of the gas engine 13 such as the engine speed and load by a sensor described later, and based on the data stored in the storage means, the differential pressure ΔP in the operating state. The optimum value of is obtained and this is set as the target value. The target value for the intermediate operating state is calculated by the interpolation method. The sampling cycle is appropriately set within 0.3 to 1 second, and feedback control of the differential pressure ΔP is performed.
That is, the control means 30 sets, for each sampling cycle, an actual differential pressure ΔP detected by a sensor described later and an optimum value of the differential pressure ΔP corresponding to the operating state of the gas engine 13 detected by a sensor described later. The deviation is calculated by the calculating means, and the control value is generated based on the deviation.

Based on this control value, the stepping motor 23 is driven via the driver 24, the opening of the pressure regulator 20 is adjusted, and the pressure of the pilot gas in the gas engine 13 is controlled. Reception of a signal from the sensor and output of the generated control signal are performed via the input / output means.

The filter in the control means 30 described above is used.
The feedback control is based on the formula below.
It is back control. S = P_rS-P_r P = KP × S I = I₀+ (S / T_i) × ΔT D = T_dX (S-S₀) / ΔT R = K × (P + I + D) However, S: deviation, P_r: Measured value of ΔP, P_rS: ΔP eyes
Standard value, P: Proportional element, KP: Proportional constant, ΔT: Sampler
Cycle, I: integral element, I₀: Last I, T _i: Integral
Constant, D: differential element, T_d: Differential component, S₀:The previous
S, R: Regulator pressure regulator screw rotation, K: Scaler
Factor.

As described above, in this example, the gas engine 1
Sensors detect the differential pressure ΔP in 3, the rotation speed of the gas engine 13, and the load of the gas engine 13. First, a strain gauge type or piezo type pressure sensor is used to detect the differential pressure ΔP. The measurement range of the sensor is 0 to 5 kgf / cm ² . Further, since the control means 30 shown in FIG. 3 needs to provide an input signal as a voltage signal of 0 to 10 V or a current signal of 4 to 20 mA, the output of the pressure sensor is set to an electric voltage of a proper voltage / current value. A device to convert the signal is required, which is usually integrated into the sensor. That is, in the case of a strain gauge type pressure sensor, a bridge circuit is built up by the sensor and an amplifier (which also functions as a power source), and the fact that the circuit resistance changes due to the pressure applied to the sensor is utilized. From which a voltage signal proportional to the pressure is obtained. In the case of a piezo-type pressure sensor, a piezo element is used for the pressure receiving part, a voltage is applied by an amplifier (which also functions as a power supply), and the change in the electric charge due to the pressure applied to the sensor is used. A voltage signal proportional to is obtained.

Any type of pressure sensor is attached to the pilot gas main pipe 3 and the air supply pipe 4, respectively. The signals sent from the two pressure sensors are input to the control means 30 as electric signals. In the control means 30, the difference between the two signals is obtained by the calculation means, and the differential pressure ΔP is calculated from this. The pressure sensor may be installed, for example, by providing a screw seat for mounting the pressure sensor on a closing flange portion attached to the end portion of the pipe or the like.

As the pressure sensor, a strain gauge type or piezo type pressure sensor as well as a differential pressure converter can be used. This is because an electric signal of 4 to 20 mA is generated by an electronic circuit that the diaphragm is displaced slightly due to the differential pressure applied to the diaphragm by the pressure applied to the diaphragm and the capacitance between the fixed electrodes facing each other changes. It is converted to and output. In this case, the pilot gas main pipe 3
From the air supply pipe 4 to the differential pressure transducer
(About 6 mm), and a signal from the differential pressure converter is input to the control means 30.

Next, the detection of the rotational speed of the gas engine 13 will be described. As shown in FIG. 4, the gas engine 13
Ring gear 25 (gear for transmitting the rotational force of the starter to the crank signal) mounted on the crankshaft of
Attach the electromagnetic pickup 26 at a right angle to the tooth surface of
The rotation of the ring gear 25 is detected by the electromagnetic pickup 26. The pulse signal output by the electromagnetic pickup 26 is F /
The voltage is converted to 0 to 10 V by the V converter 27 and input to the control means 30.

As another method, the electromagnetic pickup 26
Is used to detect the rotation of the ring gear 25, and the rotation monitor signal (4 to 20) included in the governor for engine rotation control incorporated in the control panel 28 of the generator as shown in FIG.
It is also possible to convert the pulse signal of the electromagnetic pickup 26 into a voltage using mA) and input it to the control means 30.

In the engine 13 not equipped with the ring gear 25, a light reflection type rotation detector can be used instead of the electromagnetic pickup 26. Also in this case,
The pulse output from the rotation detector is converted into a voltage and input to the control means 30.

Next, the detection of the load on the gas engine 13 will be described. As shown in FIG. 4, a power meter (kW transducer) is attached to the control panel 28 of the generator, the output thereof is converted into an electric signal (0 to 10 V or 4 to 20 mA) and input to the control means 30.

Next, a control procedure in the pilot gas pressure control device 12 of the present embodiment will be described with reference to FIG. The gas engine 13 starts, and the pressure control device 12
When the control starts, either the control mode or the setting mode is selected. In the setting mode, the target value of the differential pressure ΔP and the PID parameter are set.

In the control mode, it is first judged whether or not the rotation speed of the gas engine 13 is higher than 300 rpm (SP1). If the rotation speed exceeds 300 rpm, the rotation speed of the gas engine 13 detected by the sensor is set. Reading (SP2), ΔP corresponding to the number of rotations is calculated from the data of the storage means and set as a target value (SP3). Next, the ΔP of the gas engine 13 detected by the sensor is read (SP
4) Calculate the control value based on the above-mentioned PID feedback control formula (SP5). A pulse signal is output to the stepping motor 23 of the pressure regulator 20 based on this control value (SP6).

Next, it is judged whether or not the number of revolutions reaches the rated number of revolutions (SP7), and if not, the above S
The procedure from P1 to SP6 is repeated, and Δ
Feedback control of P is continued. When the number of revolutions is the rated number of revolutions, the process shifts to the feedback control of ΔP according to the load factor shown in SP8 to SP12 below.

When the number of revolutions has reached the rated number of revolutions, the load factor of the gas engine 13 is read by the sensor (SP8), and ΔP corresponding to the load factor is calculated from the data of the storage means to obtain the target value. Yes (SP9). Next, the ΔP of the gas engine 13 detected by the sensor is read (SP
10), a control value is calculated based on the above-mentioned PID feedback control formula (SP11). A pulse signal is output to the stepping motor 23 of the pressure regulator 20 based on this control value (SP12).

Next, it is judged whether or not the engine is stopped (SP13). If not stopped, the above SP8 to SP
The procedure of 12 is repeated, and the feedback control of ΔP according to the load factor is continued. If the engine is shut down, the control mode and the setting mode are selected.

The effectiveness of this example (embodiment) was experimentally verified by a 6-cylinder engine (cylinder diameter 260 mm) with a sampling cycle of 1 second. 6 shows the relationship of ΔP control with respect to the load factor, FIG. 7 shows the relationship with the variation of exhaust temperature with respect to the cylinder between load factors, and FIG. 8 shows the relation with the variation of P _mi with respect to the load factor between cylinders. . In addition, P _mi is a strain gauge type or piezo type pressure sensor (withstand pressure of 200 kg) for each cylinder.
f / cm ² ) is provided to measure the pressure, and this pressure data is used to calculate thermodynamically. The deviation is defined as the maximum and minimum difference between the cylinders, and is calculated by the calculation means of the control means 30.

As can be seen from the experimental results shown in FIGS. 6 to 8, according to the control device of the present example, ΔP, the variation of exhaust temperature between cylinders, and the cylinder of P _{mi in} the range of load factor 13% to 50%. Any of the fluctuations between them is improved compared to the conventional example. For example, when the load is 20%, the exhaust temperature deviation is 250 ° C.
To 145 ° C., P _mi deviation is 2.8 kgf / cm ²
To 1.5 kgf / cm ² . In this way, according to the pilot gas pressure control device 12 of the present example, the combustion of the gas fuel in the gas engine 13 is stabilized.

[0035]

According to the pilot gas pressure controller of the present invention, the pressure regulator for supplying pilot gas to the pre-combustion chamber is driven by a stepping motor, and this is controlled by the differential pressure between the pilot gas pressure and the supply pressure. Since the operation is performed by the feedback control, the pilot gas supplied to the pre-combustion chamber provided in the cylinder head becomes appropriate, and the combustion of the gas fuel in the gas engine is stabilized. .

[Brief description of drawings]

FIG. 1 is a diagram showing a lean burn gas engine having a pilot gas pressure control device according to an example of an embodiment of the present invention.

FIG. 2 is a front view of a pressure regulator used in an example of an embodiment of the present invention.

FIG. 3 is a control block diagram according to an example of an embodiment of the present invention.

FIG. 4 is a diagram showing a configuration example of a rotation speed detection sensor in an example of an embodiment of the present invention.

FIG. 5 is a flowchart showing a control procedure of the control means in the example of the embodiment of the present invention.

FIG. 6 is a load ratio and Δ in the example of the embodiment of the present invention.
It is a figure which shows the relationship of P control.

FIG. 7 is a diagram showing a relationship between a load factor and a variation in exhaust temperature between cylinders in an example of an embodiment of the present invention.

FIG. 8 is a load ratio and P in an example of the embodiment of the present invention.
It is a figure which shows the relationship with the fluctuation between cylinders of _mi .

FIG. 9 is a diagram showing a conventional gas engine.

FIG. 10 is a cross-sectional view of a pressure regulator used in a conventional gas engine.

[Explanation of symbols]

2 Pre-combustion chamber 12 Pressure control device 13 gas engine 14 Main combustion chamber 20 pressure regulator 23 Stepping motor 30 control means

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Claims (6)

(57) [Claims] 1. A pilot gas pressure control device for controlling the pressure of pilot gas supplied to a pre-combustion chamber constituting a combustion chamber of a gas engine, wherein only a pilot gas main pipe connected to the pre-combustion chamber is connected.
And a pressure regulator for adjusting the opening of a pilot gas supplied to the pre-combustion chamber by adjusting the opening degree by a stepping motor connected to a pressure adjusting screw, and an operating state detection for detecting the operating state of the gas engine. Means, differential pressure detection means for detecting a differential pressure between the pressure of the pilot gas and the supply pressure in the gas engine, and having data regarding an optimum value of the differential pressure corresponding to the operating state of the gas engine, The deviation between the optimum value of the differential pressure in the operating state of the gas engine detected by the operating state detecting means and the actual differential pressure detected by the differential pressure detecting means is obtained, and the pressure regulator is operated based on the deviation. And a control unit for controlling the pressure of pilot gas. 2. A pilot gas pressure control method for controlling the pressure of pilot gas supplied to a pre-combustion chamber constituting a combustion chamber of a gas engine, wherein the operating state of the gas engine is detected to operate the gas engine. From the data on the optimum value of the differential pressure between the pilot gas pressure and the supply pressure corresponding to the state, the optimum value of the differential pressure in the detected operating state of the gas engine is obtained, and the actual difference in the gas engine The pilot connected to the pre-combustion chamber detects the pressure and obtains the deviation between the actual differential pressure and the optimal differential pressure in the actual operating condition.
A pilot that controls a stepping motor that is connected only to a gas main pipe and that adjusts the opening of a pressure regulator that adjusts the pressure of pilot gas that is supplied to the pre-combustion chamber based on the deviation, and that controls the pressure of the pilot gas. Gas pressure control method. 3. The operating state detecting means is a rotating speed detecting means for detecting a rotating speed of the gas engine.
The pilot gas pressure control device described. 4. The pilot gas pressure control device according to claim 1, wherein the operating state detecting means is a load detecting means for detecting a load of the gas engine. 5. The pilot gas pressure control device according to claim 1, wherein said differential pressure detecting means is constituted by a strain gauge. 6. The pilot gas pressure control device according to claim 1, wherein said differential pressure detection means is constituted by a piezo element.