JP2010216399A - Engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that formation of condensate can not be inhibited when condensate is formed during operation of an engine and activity of a catalyst device is not increased due to the condensate. <P>SOLUTION: This engine includes a control device 16 and an exhaust gas temperature detection sensor 15. The control device 16 stores an ignition timing map 161 and an air fuel ratio map 162, retards ignition timing of the ignition timing map 161 and makes air fuel ratio of the air fuel ratio map 162 leaner until prescribed time tz elapses after the engine 1 starts, makes the air fuel ratio of the air fuel ratio map 162 richer if it is determined that condensate is not formed after the prescribed time tz elapses, and executes control based on the ignition timing map 161 and the air fuel ratio map 162 if it is determined that the catalyst device 13 is activated after that. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an engine having a catalyst device in an exhaust passage, and more particularly to a technique for countermeasures against condensed water generated in the exhaust passage.

Conventionally, in an engine provided with a catalyst device in an exhaust passage, a technique for countermeasures against condensed water generated in the exhaust passage has been publicly known (see, for example, Patent Document 1).
The engine described in Patent Document 1 includes a drain for discharging condensed water in an exhaust manifold.
The engine described in Patent Document 1 can discharge condensed water stored in the exhaust manifold from the drain.

JP 2004-293404 A

  However, the engine described in Patent Document 1 has a problem that when condensed water is generated during operation of the engine, the generation of condensed water cannot be suppressed, and the activity of the catalyst device is not increased by the condensed water.

  The problems to be solved by the present invention are as described above. Next, means for solving the problems will be described.

  That is, in claim 1, an engine having a catalyst device in an exhaust passage, condensed water detection means for detecting condensed water in the exhaust passage, and catalyst activity detection means for detecting the activity of the catalyst device; Control means for controlling the operating state of the engine, and the control means stores an ignition timing map that defines the ignition timing of the engine and an air-fuel ratio map that defines the air-fuel ratio of the engine. The ignition timing of the ignition timing map is retarded until a predetermined time elapses after the engine is started, the air-fuel ratio of the air-fuel ratio map is made lean, and after the predetermined time has elapsed, When it is determined that no condensed water is generated based on the detected value of the condensed water detection means, the air-fuel ratio of the air-fuel ratio map is enriched, and then the catalytic activity The catalytic converter based on a detected value of the detection means is for controlling according to the ignition timing map and the air-fuel ratio map to determine is activated.

  In claim 2, the condensed water detection means and the catalyst activity detection means are exhaust temperature detection means for detecting the temperature of the exhaust gas, and the control means includes a first threshold for the temperature of the exhaust gas, And a second threshold value related to the exhaust gas temperature higher than the first threshold value, and after the predetermined time has elapsed, the detected exhaust gas temperature is equal to or higher than the first threshold value. The catalyst device is activated when it is determined that no condensed water is generated and the air-fuel ratio in the air-fuel ratio map is enriched, and then the detected exhaust gas temperature becomes equal to or higher than the second threshold value. It judges and controls according to the said ignition timing map and the said air-fuel ratio map.

  As effects of the present invention, the following effects can be obtained.

  In claim 1, it is determined whether or not condensed water is generated during the operation of the engine, and when the condensed water is generated, control is performed so as to suppress the generation of condensed water and the catalyst device is activated. It is possible.

  According to the second aspect of the present invention, it is possible to perform control with high accuracy by detecting the temperature of the exhaust gas and determining whether or not condensed water is generated based on a threshold value related to the temperature of the exhaust gas.

The figure which showed typically the engine which concerns on one Example of this invention. Sectional drawing which showed the catalyst apparatus. Ignition timing map diagram. Air-fuel ratio map. The control flowchart of a control apparatus.

  Next, embodiments of the invention will be described.

  First, an engine 1 according to an embodiment of the present invention will be described with reference to FIG.

  In the following, for the sake of convenience, the direction in which gravity acts on the engine 1 is defined as “downward”, and the direction opposite to the direction in which gravity acts is defined as “upward”, thereby defining the “vertical direction”. The explanation will be made using the different directions.

  As shown in FIG. 1, the engine 1 is a so-called gas engine that uses a gaseous fuel such as natural gas. The engine 1 includes an engine body 10, an exhaust passage 11, a muffler 12, a catalyst device 13, an exhaust heat exchanger 14, an exhaust temperature detection sensor 15, and a control device 16.

  The engine main body 10 includes a cylinder, a cylinder block, a cylinder head, and the like, and constitutes a main body of the engine 1. The cylinder head of the engine body 10 is provided with an exhaust manifold (not shown) that collects exhaust gas discharged from the cylinder, and one end of the exhaust passage 11 is connected to the exhaust manifold.

  The exhaust passage 11 is constituted by piping or the like, and exhausts exhaust gas from the cylinder into the atmosphere. The other end of the exhaust passage 11 is connected to a muffler 12 that reduces noise accompanying exhaust gas discharge. A catalyst device 13 is provided in the middle of the exhaust passage 11, and an exhaust heat exchanger 14 is provided in the exhaust passage 11 on the muffler 12 side of the catalyst device 13.

  In the following, for convenience, the engine body 10 side in the exhaust passage 11 is defined as “exhaust upstream side”, and the muffler 12 side in the exhaust passage 11 is defined as “exhaust downstream side”, and these defined directions are used. Give an explanation.

The catalyst device 13 oxidizes and extinguishes carbon monoxide (CO), hydrocarbon (HC), etc. contained in the exhaust gas. The catalyst device 13 is an oxidation catalyst type or the like. In addition, the structure which connects the one end part of the catalyst apparatus 13 to the said exhaust manifold (the catalyst apparatus 13 is directly connected to the said exhaust manifold) may be sufficient.
The exhaust heat exchanger 14 performs heat exchange by acquiring heat of the exhaust gas and transferring thermal energy to a fluid such as water.

Next, the catalyst device 13 will be described with reference to FIG.
As shown in FIG. 2, the catalyst device 13 includes a catalyst main body 131 that serves as a filter, and a catalyst case 132 that houses the catalyst main body 131.

  The catalyst case 132 is a substantially box-shaped longitudinal member. Both ends in the longitudinal direction of the catalyst case 132 communicate with the exhaust passage 11, and the longitudinal direction of the catalyst case 132 is along the flow direction of the exhaust gas passing through the catalyst device 13. The catalyst case 132 is provided with a condensed water reservoir 132A.

  The condensed water storage part 132 </ b> A stores the condensed water generated in the exhaust passage 11. Here, the “condensed water” refers to water that is contained in the air in the exhaust passage 11 and is liquefied by being cooled by the outside air. The condensed water storage part 132 </ b> A is provided below the catalyst case 132. The condensed water reservoir 132A has a shape in which the lower surface of the catalyst case 132 bulges downward in a substantially square shape.

  The condensed water reservoir 132A is provided upstream of the exhaust gas in the catalyst device 13. That is, the condensed water reservoir 132A is provided upstream of the longitudinal center 132B of the catalyst case 132 when viewed from a direction orthogonal to the flow direction of the exhaust gas passing through the catalyst device 13. An exhaust temperature detection sensor 15 is attached in the condensed water reservoir 132A.

The exhaust temperature detection sensor 15 is an embodiment of the condensed water detection means, catalyst activity detection means, and exhaust temperature detection means according to the present invention. The exhaust temperature detection sensor 15 detects the temperature of exhaust gas (hereinafter referred to as “exhaust temperature”) Te. The condensed water detection means may be configured to detect condensed water using a float or the like.
The exhaust gas temperature detection sensor 15 (detector 151) is inserted into a condensed water reservoir 132A provided on the exhaust gas upstream side in the catalyst device 13. That is, the exhaust temperature detection sensor 15 detects the exhaust temperature Te on the exhaust upstream side in the catalyst device 13.

The control device 16 is an embodiment of the control means according to the present invention. The control device 16 has a configuration in which a CPU, a ROM, a RAM, and the like are connected by a bus, or a configuration that includes a one-chip LSI or the like. The control device 16 stores a threshold value Tz relating to the temperature of the exhaust gas. The threshold value Tz is, for example, the boiling point of condensed water (about 100 degrees).
Connected to the control device 16 are an exhaust temperature detection sensor 15, a rotation speed sensor 17, an air-fuel ratio sensor 18, and an ignition device 19 of the engine 1 (see FIG. 1).
The rotation speed sensor 17 detects the rotation speed of the crankshaft 101 of the engine 1 in this embodiment.
The air-fuel ratio sensor 18 is provided in the exhaust passage 11 and detects the air-fuel ratio of the engine 1. The “air-fuel ratio” is represented by a ratio obtained by dividing the air mass in the air-fuel mixture by the fuel mass.

  The control device 16 includes a first threshold value Tz1 related to the exhaust gas temperature, a second threshold value Tz2 related to the exhaust gas temperature higher than the first threshold value Tz1, an ignition timing map 161 (see FIG. 3), The air-fuel ratio map 162 (see FIG. 4) is stored.

The first threshold value Tz1 is a temperature lower than the second threshold value Tz2, and is defined from the viewpoint of suppressing the generation of condensed water immediately after the engine 1 is started (during cold start).
The second threshold value Tz2 is, for example, the boiling point of condensed water (about 100 degrees).

The ignition timing map 161 defines the ignition timing of the engine 1. As shown in FIG. 3, in the ignition timing map 161, the horizontal axis is represented by the engine speed N (unit: min ⁻¹ ), and the vertical axis is represented by the ignition timing T (unit: deg).
Here, the “ignition timing” is represented by the rotation angle of the crankshaft 101 (see FIG. 1) with the top dead center of the piston (not shown) of the engine 1 being 0 degrees, and the “ignition timing retard” It means that ignition is performed in a direction in which the rotation angle of 101 becomes smaller (ignition timing is delayed).

The air-fuel ratio map 162 defines the air-fuel ratio of the engine 1. As shown in FIG. 4, in the air-fuel ratio map 162, the horizontal axis is represented by the engine speed N (unit: min ⁻¹ ), and the vertical axis is represented by the air-fuel ratio A / F.
Here, “lean air-fuel ratio” means that the air mass increases or the fuel mass decreases due to an increase in air mass or a decrease in fuel mass. This means that when the air mass is reduced or the fuel mass is increased, the air-fuel ratio becomes smaller and the air-fuel mixture becomes richer.

  Next, the control flow of the control device 16 will be described with reference to FIG.

As shown in FIG. 5, the control device 16 retards the ignition timing T in the ignition timing map 161 until a predetermined time tz elapses after the engine 1 is started (S1: No) (S2).
For example, when the engine speed is Nx in FIG. 3, the control device 16 does not select the ignition timing Tx corresponding to the engine speed Nx, but the ignition timing Tx− corresponding to the engine speed N (x−1). Select 1.
The predetermined time tz is, for example, a time required for warm-up operation of the engine 1.

At the same time, the control device 16 leans the air-fuel ratio A / F of the air-fuel ratio map 162 until a predetermined time tz elapses after the engine 1 is started (S1: No) (S3).
For example, when the engine speed is Nx in FIG. 4, the control device 16 does not select the air-fuel ratio A / F (x) corresponding to the engine speed Nx, but corresponds to the engine speed N (x−1). The air / fuel ratio A / F (x-1) to be selected is selected.

Subsequently, after a predetermined time tz has elapsed since the engine 1 was started (S1: Yes), the control device 16 reads the exhaust temperature Te detected by the exhaust temperature detection sensor 15 (S4), and the exhaust temperature Te is If it is not less than the first threshold Tz1 (S5: Yes), it is determined that no condensed water is generated (S6), and the air-fuel ratio A / F of the air-fuel ratio map 162 is enriched (S7).
For example, when the engine speed is Nx in FIG. 4, the control device 16 does not select the air-fuel ratio A / F (x) corresponding to the engine speed Nx, but the sky corresponding to the engine speed N (x + 1). The fuel ratio A / F (x + 1) is selected.
On the other hand, if the exhaust gas temperature Te is less than the first threshold value Tz1 (S5: No), the control device 16 determines that condensed water is generated (S8) and retards the ignition timing T again (S8). S2), the air-fuel ratio A / F is made lean (S3).

Then, after enriching the air-fuel ratio A / F (S7), when the exhaust temperature Te becomes equal to or higher than the second threshold Tz2 (S9: Yes), the control device 16 determines that the catalyst device 13 is activated. (S10) Control is performed according to the ignition timing map 161 and the air-fuel ratio map 162 (S11).
For example, when the engine speed is Nx in FIGS. 3 and 4, the control device 16 selects the ignition timing Tx corresponding to the engine speed Nx (see FIG. 3) and the air-fuel ratio A corresponding to the engine speed Nx. / F (x) is selected (see FIG. 4).
On the other hand, if the exhaust gas temperature Te is less than the second threshold Tz2 (S9: No), the control device 16 determines that the catalyst device 13 is not activated (S12), and riches the air-fuel ratio A / F again. (S7).

As described above, the engine 1 according to one embodiment of the present invention is an engine 1 including the catalyst device 13 in the exhaust passage 11, and detects condensed water in the exhaust passage 11 and detects the activity of the catalyst device 13. An exhaust temperature detection sensor 15 for controlling the engine 1 and an operating state of the engine 1. The control device 16 defines an ignition timing map 161 that defines the ignition timing of the engine 1 and an air-fuel ratio of the engine 1. The air-fuel ratio map 162 is stored, and the ignition timing of the ignition timing map 161 is retarded and the air-fuel ratio of the air-fuel ratio map 162 is made lean until a predetermined time tz elapses after the engine 1 is started, If it is determined that condensed water is not generated based on the detection value of the exhaust temperature detection sensor 15 after the predetermined time tz has elapsed, the air-fuel ratio map The air-fuel ratio of 62 to rich, then, is to control according to the catalytic unit 13 the ignition timing and determines that the activation maps 161 and the air-fuel ratio map 162 based on the value detected by the exhaust temperature detecting sensor 15.
With such a configuration, it is determined whether or not condensed water is generated during operation of the engine 1, and control is performed to suppress the generation of condensed water when condensed water is generated, thereby activating the catalyst device 13. It is possible to

The condensed water detection means is an exhaust temperature detection sensor 15 that detects the temperature of the exhaust gas, and the control device 16 has an exhaust gas that is higher than the first threshold value Tz1 related to the exhaust gas temperature and the first threshold value Tz1. The second threshold value Tz2 relating to the gas temperature is stored, and after a predetermined time tz has elapsed, the detected exhaust gas temperature Te is not less than the first threshold value Tz1 and less than the second threshold value Tz2. If it is determined that condensed water is generated, the air-fuel ratio of the air-fuel ratio map 162 is enriched, and then the detected exhaust gas temperature Te is equal to or higher than the second threshold Tz2, the condensed water is not generated. It is determined and controlled according to the ignition timing map 161 and the air-fuel ratio map 162.
With such a configuration, highly accurate control is possible by detecting the temperature Te of the exhaust gas and determining whether or not condensed water is generated based on the threshold values Tz1 and Tz2 applied to the temperature of the exhaust gas. is there.

DESCRIPTION OF SYMBOLS 1 Engine 11 Exhaust passage 13 Catalytic device 15 Exhaust temperature detection sensor (Condensate detection means, catalyst activity detection means, exhaust temperature detection means)
16 Control device (control means)
132A Condensate storage portion 161 Ignition timing map 162 Air-fuel ratio map Te Exhaust gas temperature Tz1 First threshold Tz2 Second threshold tz Predetermined time

Claims (2)

  An engine having a catalyst device in an exhaust passage, the condensed water detection means for detecting condensed water in the exhaust passage, the catalyst activity detection means for detecting the activity of the catalyst device, and the operating state of the engine is controlled And a control means for storing the ignition timing map defining the ignition timing of the engine and an air-fuel ratio map defining the air-fuel ratio of the engine, and after the engine is started Until the predetermined time elapses, the ignition timing of the ignition timing map is retarded, the air-fuel ratio of the air-fuel ratio map is made lean, and after the predetermined time has elapsed, the detected value of the condensed water detection means is obtained. If it is determined that no condensed water is generated, the air-fuel ratio of the air-fuel ratio map is enriched, and thereafter, based on the detected value of the catalyst activation detecting means Engine catalytic converter is controlled according to the ignition timing map and the air-fuel ratio map to determine is activated.   The condensed water detection means and the catalyst activity detection means are exhaust temperature detection means for detecting the temperature of exhaust gas, and the control means includes a first threshold on the temperature of exhaust gas and the first threshold. A second threshold value for a higher exhaust gas temperature, and after the predetermined time has elapsed, if the detected exhaust gas temperature is equal to or higher than the first threshold value, condensed water is generated. If the detected exhaust gas temperature is equal to or higher than the second threshold value, the catalyst device is determined to be activated and the ignition timing is determined. The engine according to claim 1, wherein the engine is controlled according to a map and the air-fuel ratio map.

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