JP4658911B2 - Air-fuel ratio control device for generator driving engine - Google Patents

Description

  The present invention relates to an engine for driving a generator having a catalyst device installed in an exhaust passage, the engine driving engine having an engine load shut-off device and a synchronizer for synchronizing the generated power of the generator and commercial power. The present invention relates to a fuel ratio control device.

An engine (internal combustion engine) is equipped with a NOx reduction catalyst device in an exhaust passage at a supercharger outlet and an oxidation catalyst device such as HC, and many techniques are provided as means for promoting the activation of the catalyst device. ing.
One of the activation techniques of such a catalyst device is a technique disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2000-257479).

  In such a technique, the temperature of the catalyst installed in the exhaust passage is detected, the engine operating state such as the engine load is detected, and air-fuel ratio control means for controlling the target air-fuel ratio of the engine according to the engine operating state is provided, and the catalyst When the temperature is lower than the target activation temperature, the target air-fuel ratio is set to an activated lean air-fuel ratio that is higher than the normal air-fuel ratio and higher than the stoichiometric air-fuel ratio. The catalyst function is improved to improve the startability of the catalyst function, and the exhaust gas purification performance of the catalyst device is improved.

JP 2000-257479 A

  In a gas engine-driven power generation system, when the engine is stopped, the engine is normally stopped after a no-load operation is performed for a certain period of time. In such an engine, the air-fuel ratio is set to the rich side (high rich side) with respect to the required air-fuel ratio at the time of no-load steady state in order to earn surplus output in the moving region where the load is shifted from no load to light load operation. The air-fuel ratio in the no-load region during the engine stop operation as described above is closer to the rich side (high rich side) than the required air-fuel ratio.

  However, in a gas engine-driven power generation system in which an oxidation catalyst device is installed in the exhaust passage, if the no-load operation is performed for a certain period of time during the engine stop operation as described above, the air-fuel ratio becomes excessive on the engine-required air-fuel ratio side. Because it is close to the (high-rich side), unburned gas emissions from the engine increase during such no-load operation, and this unburned gas reacts rapidly in the oxidation catalyst device, causing the temperature of the oxidation catalyst to rise rapidly. In addition to reducing the function of the oxidation catalyst, the durability of the oxidation catalyst is greatly reduced.

  In order to avoid the occurrence of the above-mentioned problem, if the air-fuel ratio in the no-load operation range is diluted (lean) in accordance with the engine required air-fuel ratio, the temperature increase of the oxidation catalyst as described above can be avoided. In this way, when the air-fuel ratio is made lean, the surplus output in the moving region where the load is shifted from no load to light load decreases, and the engine cannot be loaded smoothly, resulting in a decrease in the operating performance of the power generation system. .

  In view of the problems of the prior art, the present invention avoids an excessive temperature rise of the catalyst device installed in the exhaust passage when performing no-load operation by a load cutoff signal from the load cutoff device during engine stop operation. In addition to preventing the catalyst from degrading and improving its durability, it is possible to ensure a surplus output in the moving range from no-load to light-load operation and smoothly shift to load operation, maintaining high operating performance of the power generation system. An object of the present invention is to provide an air-fuel ratio control device for an engine for driving a generator.

The present invention achieves the above-mentioned object. In the engine for driving a generator provided with a catalyst device in an exhaust passage, and equipped with a load interrupting device for interrupting the engine load and a synchronizer with commercial power, the load When an engine load cut-off signal is transmitted from the shut-off device, the engine air-fuel ratio is set to a lean air-fuel ratio exceeding a certain air-fuel ratio, and the generated power of the generator from the synchronizer and the commercial power are synchronized. A controller for setting the air-fuel ratio to a normal air-fuel ratio equal to or lower than the constant air-fuel ratio when a synchronization signal to be transmitted is transmitted ; and an exhaust temperature sensor for detecting an exhaust temperature of the engine and inputting the detected temperature to the controller; An engine oil temperature sensor that detects an oil temperature of the engine and inputs the detected oil temperature to the controller, and the controller detects the exhaust temperature. No-load operation with the engine load cut off when either is higher than a preset reference exhaust temperature or the detected value of the engine oil temperature is higher than a preset reference engine oil temperature or both When the load cut-off signal is input, the lean air-fuel ratio control is entered .

In addition to such invention, not the preferred constructed as follows.

The exhaust catalyst temperature rise detection means for input to the controller to detect the exhaust gas temperature increase degree of the oxidation catalyst device is provided, said controller, said when the exhaust temperature increase degree of the reference exhaust temperature rise of less that is set in advance, synchronizing signal from the lean air-fuel ratio operation after load rejection is Ru is configured to transition to the normal air-fuel ratio operation after being originated.

According to the present invention, the controller receives the transmission of a load cutoff signal from the load cutoff device and sets the air / fuel ratio of the engine to a lean air / fuel ratio that exceeds a certain air / fuel ratio, thereby suppressing an increase in exhaust gas temperature. It becomes possible to perform the operation, and the amount of unburned gas discharged from the engine can be reduced, whereby the temperature rise of the catalyst accompanying the combustion of unburned gas in the catalyst device can be prevented.
On the other hand, when a synchronization signal is generated to synchronize the generated power of the generator and the commercial power from the synchronizer, simultaneously with the transition from no-load operation to load operation, the lean air-fuel ratio exceeding a certain air-fuel ratio is less than the certain air-fuel ratio Since the engine is operated by shifting to the normal air-fuel ratio, it is possible to ensure surplus output in the moving region where the operation shifts from no-load operation to load operation in synchronization with commercial power, and smooth load operation Thus, the operation performance of the power generation system can be kept high.

  Therefore, according to the present invention, when performing no-load operation by the load cutoff signal from the load cutoff device, it is possible to avoid an excessive temperature rise of the catalyst device installed in the exhaust passage and to prevent a deterioration in the function of the catalyst, and its durability. The surplus output in the movement region from no load to load operation can be secured, and the operation can be smoothly shifted to the load operation, so that the operation performance of the power generation system can be kept high.

According to the present invention, either or both of the case where the detected value of the engine exhaust temperature is equal to or higher than a preset reference exhaust temperature, or the detected value of the engine oil temperature is equal to or higher than a preset reference engine oil temperature. After confirming that it is satisfied, the engine is configured to shift to lean air-fuel ratio control in response to an engine load cutoff signal, so the exhaust temperature and engine oil temperature will be above the reference temperature, and stable operation without occurrence of misfire etc. In this state, it is possible to shift to a no-load operation at a lean air-fuel ratio.
Furthermore, the exhaust gas temperature rise degree in the catalyst device is detected, and the actual exhaust gas temperature rise degree is maintained so as to be equal to or lower than the reference exhaust gas temperature rise degree, that is, the allowable exhaust gas rise degree. If it is configured to shift to the load operation at the normal air-fuel ratio, the load operation can be performed while the temperature of the catalyst device is always kept below the allowable temperature.

  Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this example are not intended to limit the scope of the present invention only to specific examples unless otherwise specified. Only.

FIG. 1 is an overall configuration diagram of a generator drive gas engine control system according to an embodiment of the present invention.
In FIG. 1, a gas engine (hereinafter referred to as an engine) is denoted by reference numeral 100, and the exhaust gas that has passed through the exhaust outlet pipe 102 of the engine 100 drives the turbine 107 a guided to the turbine 107 a of the supercharger 107. In the supercharger 107, a compressor 107b coaxial with the turbine 107a is rotationally driven to pressurize the intake air introduced through the supercharger inlet air supply pipe 105a as will be described later. Then, the air is supplied into the cylinder of the engine 100 through the air cooler 104.

A gas mixer 105 is installed in the middle of the supercharger inlet air supply pipe 105a, the fuel gas supplied through the fuel gas pipe 106a and the gas amount adjusting valve 106, and the gas mixer 105 through the supercharger inlet air supply pipe 105a. Mix with the air supplied to The supply air, which is a mixture of fuel gas and air from the gas mixer 105, is pressurized by the compressor 107b of the supercharger 107, cooled by the air cooler 104, and then passed through the supply air pipe 101. 100 cylinders are supplied.
The exhaust gas after driving the turbine 107a of the supercharger 107 is introduced into the oxidation catalyst device 104 through the exhaust pipe 103, and unburned components such as HC are burned and removed in the oxidation catalyst device 104. It is purified and discharged into the outside air.

An engine controller 12 and a generator control panel 11 are provided for controlling the engine and a generator (not shown) that is directly connected to the engine, and both are connected by a control line.
The engine control device 12 and the generator control panel 11 constitute a controller 10, which includes the detected value of the exhaust temperature at the outlet of the engine 1 from the exhaust temperature sensor 3, and the oxidation catalyst from the exhaust temperature sensor 1 at the oxidation catalyst inlet. The detected value of the exhaust gas temperature at the inlet of the device 104, the detected value of the exhaust gas temperature at the outlet of the oxidation catalyst device 104 from the oxidation catalyst outlet exhaust temperature sensor 2, and the detected value of the engine oil temperature from the engine oil temperature sensor 4 are input.
FIG. 1 shows that the detected values are input to the generator control panel 11. In short, the detected values are a controller including the generator control panel 11 and the engine control device 12. 10 may be used for the control calculation described later.

The generator control panel 11 is provided with a load interrupting device 5 for interrupting a generator load, that is, a load applied to the engine 100, and a synchronizing device 6 for transmitting a synchronizing signal for synchronizing the generated power and commercial power of the generator. A load cutoff signal from the cutoff device and a synchronization signal between the generated power of the generator and the commercial power from the synchronization device 6 are input to the engine control device 12.
Then, the engine control device 12 performs calculation and control, which will be described later, and controls the opening of the gas amount adjusting valve 106 based on the output signal.

Next, the operation of this embodiment will be described with reference to FIGS.
FIG. 2 is a control block diagram of the air-fuel ratio control apparatus in the embodiment.
In FIG. 2, the detected value of the engine outlet exhaust temperature from the exhaust temperature sensor 3 is input to the exhaust temperature determination means 110 of the controller 10. The detected value of the engine oil temperature from the engine oil temperature sensor 4 is input to the engine oil temperature determining means 120 of the controller 10.
The exhaust temperature determination means 110 determines that the no-load operation is possible when the exhaust gas temperature is equal to or higher than a preset reference exhaust temperature, that is, the minimum exhaust temperature at which the engine can stably operate without load by lean air-fuel ratio control. Further, the engine oil temperature determination means 120 can perform the no-load operation when the engine oil temperature is equal to or higher than a preset reference engine oil temperature, that is, the engine oil temperature is equal to or higher than a minimum engine oil temperature at which the engine can be stably driven without load by lean air-fuel ratio control. to decide.

The judgment result by the exhaust temperature judgment means 110 and the judgment result by the engine oil temperature judgment means 120 are input to the air / fuel ratio control necessity judgment means 13, and the air / fuel ratio control necessity judgment means 13 inputs the exhaust temperature. When either or both of the determination result by the determination unit 110 and the determination result by the engine oil temperature determination unit 120 are the determination result that the no-load operation is possible by the lean air-fuel ratio control, the no-load operation by the lean air-fuel ratio control is possible. Is output to the air-fuel ratio setting means 14.
By controlling in this way, the exhaust temperature and the engine oil temperature become equal to or higher than the reference temperature, and it is possible to shift to a no-load operation at a lean air-fuel ratio in a stable state without occurrence of misfire or the like.

When a load cutoff signal from the load cutoff device 5 is input to the air-fuel ratio setting means 14 of the controller 10, the air-fuel ratio setting means 14 sets the air-fuel ratio of the engine 1 in the left column of FIG. As shown , a lean air-fuel ratio exceeding a certain air-fuel ratio capable of no-load operation is set and input to the air-fuel ratio correcting means 16. The air-fuel ratio correction means 16 inputs the set value of the lean air-fuel ratio to the gas amount adjustment valve opening calculation means 17 without performing correction at the catalyst temperature described later during no-load operation.
In the gas amount adjusting valve opening calculating means 17, the opening of the gas amount adjusting valve 106 corresponding to the lean air-fuel ratio is calculated and inputted to the gas amount adjusting valve 106. The opening is controlled to correspond to the air-fuel ratio.

When a synchronization signal for synchronizing the generated power of the generator and the commercial power is transmitted from the synchronization device 6 in such a no-load operation state, the air-fuel ratio setting means 14 displays the air-fuel ratio of the engine 1 as a graph. As shown in the middle column of 3, the lean air-fuel ratio exceeding the constant air-fuel ratio is shifted to the normal air-fuel ratio. Next, the engine control device 12 causes the engine 100 to perform a no-load operation for a predetermined time at the normal air-fuel ratio, and then shifts to a load operation as shown in the right column of FIG.

The detected value of the oxidation catalyst device 104 inlet exhaust temperature from the oxidation catalyst inlet exhaust temperature sensor 1 and the detected value of the oxidation catalyst device 104 outlet exhaust temperature from the oxidation catalyst outlet exhaust temperature sensor 2 are calculated by calculating the catalyst temperature of the controller 10. Input to means 15. The catalyst temperature increase calculating means 15 calculates the temperature increase of the exhaust gas in the oxidation catalyst device 104 from the temperature difference between the oxidation catalyst device outlet exhaust temperature and the oxidation catalyst device inlet exhaust temperature, and the air-fuel ratio correction means. 16
As shown in FIG. 4, the air-fuel ratio correction means 17 is set with a relationship between the temperature rise of the exhaust gas in the oxidation catalyst device 104, that is, the catalyst temperature rise and the air-fuel ratio. Such a set value is stepwise empty when the air-fuel ratio is made lean as the catalyst temperature rises as shown in line A in FIG. 4, or when the allowable (reference) exhaust gas temperature rise Tcx is exceeded as shown in line B in FIG. It is possible to select whether the fuel ratio is lean.

In the air-fuel ratio correcting means 16, when the exhaust gas temperature rise (catalyst temperature rise) exceeds the allowable (reference) exhaust gas temperature rise Tcx, the exhaust gas temperature rise falls below the allowable exhaust gas temperature rise Tcx. Thus, the air-fuel ratio is corrected to the lean side and input to the gas amount adjusting valve opening calculating means 17. In the gas amount adjusting valve opening calculating means 17, the opening of the gas amount adjusting valve 106 corresponding to the corrected air-fuel ratio is calculated and input to the gas amount adjusting valve 106, and the gas amount adjusting valve 106 The degree of opening corresponding to the lean air-fuel ratio is controlled.
If comprised in this way, while detecting the exhaust gas temperature rise degree in the oxidation catalyst apparatus 104, and hold | maintaining so that an actual exhaust gas temperature rise degree may become below the reference | standard exhaust gas temperature rise degree, ie, the said allowable exhaust gas rise degree Tcx, It is possible to shift from the no-load operation at the lean air-fuel ratio to the load operation at the normal air-fuel ratio, and the load operation can be performed while the temperature of the oxidation catalyst device 104 is always kept below the allowable temperature.

According to the above embodiment, the controller 10 increases the exhaust gas temperature by setting the air / fuel ratio of the engine 100 to a lean air / fuel ratio exceeding a certain air / fuel ratio in response to the transmission of the load cutoff signal from the load interrupting device 5. This makes it possible to perform no-load operation while suppressing the amount of unburned gas discharged from the engine 100, thereby preventing the temperature of the catalyst from increasing due to the combustion of unburned gas in the oxidation catalyst device 104. it can.
On the other hand, when a synchronization signal for synchronizing the generated power of the generator and the commercial power is transmitted from the synchronization device 6, simultaneously with the transition from the no-load operation to the load operation, the lean air-fuel ratio exceeding the constant air-fuel ratio is changed to the constant air-fuel ratio. Since the engine 100 is operated by shifting to a normal air-fuel ratio equal to or lower than the fuel ratio, it is possible to ensure surplus output in a moving region in which the operation shifts from no-load operation to load operation in synchronization with commercial power. Therefore, the operation performance of the power generation system can be kept high.

  Therefore, according to this embodiment, when performing no-load operation by the load cutoff signal from the load cutoff device 5, it is possible to avoid an excessive temperature rise of the oxidation catalyst device 104 installed in the exhaust pipe 103 and to reduce the function of the catalyst. It is possible to prevent and improve the durability, and it is possible to secure a surplus output in the movement region from no load to load operation, and to smoothly shift to load operation, thereby improving the operation performance of the power generation system. Can be held.

  According to the present invention, when performing no-load operation with a load cutoff signal from the load cutoff device during engine stop operation, the excessive deterioration of the temperature of the catalyst device installed in the exhaust passage is avoided to reduce the function of the catalyst. A generator-driven engine that can prevent and improve its durability, and can ensure a surplus output in the moving area from no-load to light-load operation so that it can smoothly shift to load operation and maintain high operating performance of the power generation system. The air-fuel ratio control apparatus can be provided.

1 is an overall configuration diagram of a generator drive gas engine control system according to an embodiment of the present invention. It is a control block diagram of the air-fuel ratio control apparatus in the embodiment. It is a table | surface which shows the air fuel ratio control conditions of the engine in the said Example. FIG. 3 is a relationship diagram between an oxidation catalyst temperature and an air-fuel ratio in the embodiment.

DESCRIPTION OF SYMBOLS 1 Oxidation catalyst inlet exhaust temperature sensor 2 Oxidation catalyst outlet exhaust temperature sensor 3 Exhaust temperature sensor 4 Engine oil temperature sensor 5 Load shut-off device 6 Synchronous device 10 Controller 11 Generator control panel 12 Engine control device 100 Gas engine (engine)
DESCRIPTION OF SYMBOLS 101 Supply pipe 102 Exhaust outlet pipe 103 Exhaust pipe 104 Oxidation catalyst apparatus 105 Gas mixer 106 Gas quantity adjustment valve 107 Supercharger

Claims (3)

In a generator driving engine having a catalyst device in the exhaust passage and a load interrupting device for interrupting the engine load and a synchronizer with commercial power,
When an engine load shut-off signal is transmitted from the load shut-off device, the engine air-fuel ratio is set to a lean air-fuel ratio exceeding a certain air-fuel ratio, and the generator generated power and commercial power from the synchronizer A controller for setting the air-fuel ratio to a normal air-fuel ratio equal to or lower than the constant air-fuel ratio when a synchronization signal for synchronizing the
Further, an exhaust temperature sensor that detects an exhaust temperature of the engine and inputs the detected temperature to the controller, and an engine oil temperature sensor that detects an oil temperature of the engine and inputs the detected temperature to the controller are provided. When the detected value of the engine is higher than a preset reference exhaust temperature or the detected value of the engine oil temperature is higher than a preset reference engine oil temperature or both, the engine load is shut off. An air-fuel ratio control apparatus for an engine for driving a generator, which is configured to shift to the lean air-fuel ratio control when it is determined that no-load operation is possible and the load cutoff signal is input . Catalytic device temperature rise detection means for detecting the exhaust gas temperature rise degree in the oxidation catalyst device and inputting it to the controller is provided, the controller, when the exhaust temperature rise degree is less than or equal to a preset reference exhaust temperature rise degree, 2. The air-fuel ratio control device for an engine for driving a generator according to claim 1 , wherein the lean air-fuel ratio operation after the load is interrupted is shifted to a normal air-fuel ratio operation after a synchronization signal is transmitted. . A generator driving engine comprising the air-fuel ratio control device according to claim 1.

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