Engine device

Abstract

To more appropriately respond to both of a request for suppression of discharge of particulate matters from an engine and a request for warming-up of a catalyst.SOLUTION: An engine device includes an engine, a catalyst for purifying exhaust gas of the engine, and a control device for controlling the engine. The control device executes catalyst warming-up control for controlling the engine so as to promote warming-up of the catalyst when warming-up of the catalyst is requested after completion of starting of the engine, and executes particulate matter suppression control for controlling the engine so as to suppress discharge of particulate matters when warming-up of the catalyst is not requested and suppression of discharge of particulate matters is requested.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an engine device.

Background Art

[0002] Conventionally, as this type of engine device, an engine having an in-cylinder injection valve that injects fuel into a cylinder and a catalyst attached to an exhaust system of the engine have been proposed (for example, see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In such an engine device, after the engine starts up, both suppression of particulate matter emissions and catalyst warm-up may be required, and how to deal with this case has been an issue.

[0005] The main object of the engine device of the present invention is to more appropriately deal with the case where both suppression of particulate matter emissions from the engine and catalyst warm-up are required.

Means for Solving the Problems

[0006] The engine device of the present invention has taken the following means to achieve the above main object.

[0007] The engine device of the present invention includes an engine, a catalyst that purifies the exhaust of the engine, a control device that controls the engine, and is an engine device comprising: the control device is After the engine has completed starting, when warm-up of the catalyst is required, catalyst warm-up control is executed to control the engine so as to promote warm-up of the catalyst, when warm-up of the catalyst is not required and suppression of particulate matter emissions is required, particulate matter suppression control is executed to control the engine so as to suppress emissions of the particulate matter, which is the gist.

[0008] In the engine device of the present invention, after the engine has completed starting, when warm-up of the catalyst is required, catalyst warm-up control is executed to control the engine so as to promote warm-up of the catalyst, and when warm-up of the catalyst is not required and suppression of particulate matter emissions is required, particulate matter suppression control is executed to control the engine so as to suppress emissions of the particulate matter. That is, when both warm-up of the catalyst and suppression of particulate matter emissions are required, the catalyst warm-up control is executed with priority over the particulate matter suppression control. Thereby, it is possible to suppress an increase in the time required for activation of the catalyst.

[0009] In the engine device of the present invention, the engine has an in-cylinder injection valve that injects fuel into the cylinder, and in the particulate matter suppression control, the control device may perform fuel injection from the in-cylinder injection valve in two stages during the intake stroke. Further, in the catalyst warm-up control, the control device may perform ignition retard.

[0010] In the engine device of the present invention, after the engine has completed starting, when warm-up of the catalyst is not required, when the integrated air amount is less than the threshold value, if suppression of particulate matter emissions is required, the particulate matter suppression control may be executed. In this case, the threshold value may be set to increase as the coolant water temperature of the engine is lower.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0012] Next, embodiments for carrying out the present invention will be described using examples.

Examples

[0013] FIG. 1 is a configuration diagram showing an outline of the configuration of an engine device 10 as an embodiment of the present invention. As shown in the figure, the engine device 10 of the embodiment includes an engine 12, a fuel supply device 50, and an electronic control unit 70 (control device). This engine device 10 is mounted on, for example, an engine vehicle that runs using the power from the engine 12 and can perform so-called idle stop, or a hybrid vehicle that includes a motor in addition to the engine 12 and can run while intermittently operating the engine 12.

[0014] The engine 12 is configured as an internal combustion engine that outputs power by four strokes of intake, compression, expansion, and exhaust using, for example, gasoline or a mixed fuel of gasoline and alcohol as fuel. This engine 12 includes a port injection valve 25 that injects fuel into the intake port and an in-cylinder injection valve 26 that injects fuel into the cylinder. By including the port injection valve 25 and the in-cylinder injection valve 26, the engine 12 can be operated in any of a port injection mode, an in-cylinder injection mode, and a common injection mode.

[0015] In the port injection mode, the air cleaned by the air cleaner 22 is inhaled into the intake pipe 23, passed through the throttle valve 24, and fuel is injected from the port injection valve 25 to mix the air and fuel. Then, this air-fuel mixture is inhaled into the combustion chamber 29 through the intake valve 28, and is explosively combusted by the electric spark from the spark plug 30. The reciprocating motion of the piston 32 pushed down in the cylinder bore 31 by the energy of the explosive combustion is converted into the rotational motion of the crankshaft 14. In the in-cylinder injection mode, air is inhaled into the combustion chamber 29 in the same manner as in the port injection mode, fuel is injected from the in-cylinder injection valve 26 during the intake stroke and the compression stroke, and is explosively combusted by the electric spark from the spark plug 30 to obtain the rotational motion of the crankshaft 14. In the common injection mode, fuel is injected from the port injection valve 25 when air is inhaled into the combustion chamber 29, and fuel is injected from the in-cylinder injection valve 26 during the intake stroke and the compression stroke, and is explosively combusted by the electric spark from the spark plug 30 to obtain the rotational motion of the crankshaft 14. These injection modes are switched based on the operating state of the engine 12 and the like. The exhaust discharged from the combustion chamber 29 to the exhaust pipe 34 through the exhaust valve 33 is discharged to the outside air through the purification device 35. The purification device 35 has a catalyst (three-way catalyst) 34a that purifies harmful components such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx). Note that the catalyst 35a may be a four-way catalyst that combines the purification function of the three-way catalyst and the collection function of collecting particulate matter (PM) such as soot in the exhaust gas.

[0016] The fuel supply device 50 is configured as a device that supplies the fuel in the fuel tank 51 to the port injection valve 25 and the in-cylinder injection valve 26 of the engine 12. The fuel supply device 50 includes a fuel tank 51, a feed pump 52, a low-pressure supply pipe 53, a check valve 54, a relief pipe 55, a relief valve 56, a high-pressure pump 57, and a high-pressure supply pipe 58.

[0017] The feed pump 52 is configured as an electric pump that operates receiving power supply from a battery (not shown) and is disposed in the fuel tank 51. This feed pump 52 supplies the fuel in the fuel tank 51 to the low-pressure supply pipe 53. The low-pressure supply pipe 53 is connected to the port injection valve 25. The check valve 54 is provided in the low-pressure supply pipe 53, allows the flow of fuel in the direction from the feed pump 52 side to the port injection valve 25 side, and restricts the flow of fuel in the reverse direction.

[0018] The relief pipe 55 is connected to the low-pressure supply pipe 53 and the fuel tank 51. The relief valve 56 is provided in the relief pipe 55, closes the valve when the fuel pressure in the low-pressure supply pipe 53 is less than the threshold value Pflolim, and opens the valve when the fuel pressure in the low-pressure supply pipe 53 is equal to or greater than the threshold value Pflolim. When the relief valve 56 opens, a part of the fuel in the low-pressure supply pipe 53 is returned to the fuel tank 51 via the relief pipe 55. In this way, it suppresses the fuel pressure in the low-pressure supply pipe 53 from becoming excessive.

[0019] The high-pressure pump 57 is configured as a pump that is driven by the power from the engine 12 (in the embodiment, the rotation of the intake camshaft that opens and closes the intake valve 28) and pressurizes the fuel in the low-pressure supply pipe 53 and supplies it to the high-pressure supply pipe 58. The high-pressure pump 57 has an electromagnetic valve 57a that is connected to its suction port and opens and closes when pressurizing the fuel, a check valve 57b that is connected to its discharge port and restricts the reverse flow of fuel and holds the fuel pressure in the high-pressure supply pipe 58, and a plunger 57c that operates (moves in the vertical direction in FIG. 1) by the rotation of the engine 12 (rotation of the intake camshaft). This high-pressure pump 57, during the operation of the engine 12, when the electromagnetic valve 57a is opened, sucks the fuel in the low-pressure supply pipe 53, and when the electromagnetic valve 57a is closed, intermittently sends the fuel compressed by the plunger 57c to the high-pressure supply pipe 58 via the check valve 57b, thereby pressurizing the fuel supplied to the high-pressure supply pipe 58.

[0020] The electronic control unit 70 includes a microcomputer having a CPU 71, a ROM 72, a RAM 73, a flash memory 74, and input / output ports. Signals from various sensors are input to the electronic control unit 70 via the input ports. Examples of the signals input to the electronic control unit 70 include the crank angle θcr from the crank position sensor 14a that detects the rotational position of the crankshaft 14 of the engine 12, and the coolant temperature Tw from the water temperature sensor 15 that detects the temperature of the coolant of the engine 12. Also included are the cam angles θci and θco from the cam position sensor 16 that detects the rotational position of the intake camshaft that opens and closes the intake valve 28 and the rotational position of the exhaust camshaft that opens and closes the exhaust valve 33. Further examples include the throttle opening TH from the throttle position sensor 24a that detects the position of the throttle valve 24, the intake air amount Qa from the air flow meter 23a attached upstream of the throttle valve 24 in the intake pipe 23, and the intake air temperature Ta from the temperature sensor 23t attached upstream of the throttle valve 24 in the intake pipe 23. Additionally, there are the front air-fuel ratio AFf from the front air-fuel ratio sensor 37 attached upstream of the purification device 35 in the exhaust pipe 34, and the rear air-fuel ratio AFr from the rear air-fuel ratio sensor 38 attached downstream of the purification device 35 in the exhaust pipe 34. Also included are the fuel temperature Tftnk from the fuel temperature sensor 51t attached to the fuel tank 51, the rotational speed Np of the feed pump 52 from the rotational speed sensor 52a attached to the feed pump 52, the low-pressure fuel pressure (the pressure of the fuel supplied to the port injection valve 25) PL from the fuel pressure sensor 53p attached near the port injection valve 25 (e.g., the low-pressure delivery pipe) in the low-pressure supply pipe 53, and the high-pressure fuel pressure (the pressure of the fuel supplied to the in-cylinder injection valve 26) PH from the fuel pressure sensor 58p attached near the in-cylinder injection valve 26 (e.g., the high-pressure delivery pipe) in the high-pressure supply pipe 58.

[0021] From the electronic control unit 70, various control signals are output via the output ports. Examples of the signals output from the electronic control unit 70 include a control signal to the throttle valve 24 of the engine 12, a control signal to the port injection valve 25, a control signal to the in-cylinder injection valve 26, and a control signal to the ignition plug 30. Also included are a control signal to the feed pump 52 of the fuel supply device 50 and a control signal to the electromagnetic valve 57a of the high-pressure pump 57.

[0022] The electronic control unit 70 calculates the engine speed Ne of the engine 12 based on the crank angle θcr from the crank position sensor 14a. Further, the electronic control unit 70 calculates the load ratio KL (the ratio of the volume of air actually inhaled in one cycle to the stroke volume per cycle of the engine 12) based on the intake air amount Qa from the air flow meter 23a and the engine speed Ne of the engine 12. Furthermore, the electronic control unit 70 estimates the temperature Tc of the catalyst 35a of the purification device 35 based on the cooling water temperature Tw from the water temperature sensor 15, the engine speed Ne of the engine 12, the load ratio KL, and the ignition timing.

[0023] In the engine device 10 of the embodiment configured in this way, the CPU 71 of the electronic control unit 70 performs intake air amount control, fuel injection control, and ignition control of the engine 12 based on the target load ratio KL* required for the engine 12, and also controls the feed pump 52 and the high-pressure pump 57 (electromagnetic valve 57a) of the fuel supply device 50. Here, for the control of the engine 12, basically, fuel injection control is performed in either the port injection mode, the in-cylinder injection mode, or the common injection mode in consideration of fuel consumption, fuel dilution, emissions, drivability, etc., and ignition control is performed at the optimum ignition timing. Hereinafter, such control of the engine 12 is referred to as "normal control".

[0024] Also, in the engine device 10 of the embodiment, when the starting condition of the engine 12 is satisfied, the engine 12 is started. Here, the starting of the engine 12 is performed by cranking the engine 12 with a motor (not shown) and starting the fuel injection control and ignition control of the engine 12. The determination of the completion of the starting of the engine 12 is made when fuel injection for a predetermined cycle (for example, 2 cycles) is performed for each cylinder of the engine 12, when the complete explosion of the engine 12 is detected, or when the high-pressure fuel pressure PH reaches a threshold value PHref or more along with the operation of the high-pressure pump 57.

[0025] Next, the operation of the engine device 10 of the embodiment, particularly the operation after the completion of starting in the engine 12, will be described. FIG. 2 is a flowchart showing an example of a post-start control routine executed by the electronic control unit 70. This routine is executed when the starting of the engine 12 is completed. In the embodiment, the case of the in-cylinder injection mode will be described.

[0026] When the post-start control routine in FIG. 2 is executed, the electronic control unit 70 first inputs the coolant water temperature Tw, the integrated air amount Qas, and the catalyst warm-up request flag Fc (step S100). Here, the coolant water temperature Tw is detected by the water temperature sensor 15. The integrated air amount Qas is calculated as the integrated value of the intake air amount Qa detected by the air flow meter 23a from the start of the starting (start of cranking) of the engine 12. The catalyst warm-up request flag Fc is set to a value of 1 when the warm-up (catalyst warm-up) of the catalyst 35a is requested, and is set to a value of 0 when the catalyst warm-up is not requested (completed). The request for catalyst warm-up is made when the temperature Tc of the catalyst 35a estimated based on the coolant water temperature Tw, the rotational speed Ne, the load factor KL, and the ignition timing is less than the threshold value Tcref (the catalyst 35a is inactive).

[0027] When data is input in this way, the value of the catalyst warm-up request flag Fc is examined (step S110). When the catalyst warm-up request flag Fc has a value of 1, it is determined that catalyst warm-up is requested, and catalyst warm-up control is executed to control the engine 12 so as to promote catalyst warm-up (step S120), and the process returns to step S100. In the catalyst warm-up control, for example, fuel of a target fuel injection amount set so that the output of the engine 12 (intake air amount Qa) becomes an output Pe1 (intake air amount Qa1) suitable for catalyst warm-up and the air-fuel ratio becomes lean is injected from the in-cylinder injection valve 26 in the intake stroke and / or the compression stroke, and the ignition timing is made sufficiently later than the optimum ignition timing. Thereby, the warm-up of the catalyst 35a can be promoted.

[0028] When the catalyst warm-up request flag Fc has a value of 0 in step S110, it is determined that catalyst warm-up is not requested, and a threshold value Qasref is set based on the coolant temperature Tw (step S130), and the integrated air amount Qas is compared with the threshold value Qasref (step S140). Here, the threshold value Qasref is a threshold value used to determine whether or not suppression of particulate matter emissions is required. In the embodiment, the coolant temperature Tw is applied to a threshold value setting map in which the relationship between the coolant temperature Tw and the threshold value Qasref is determined in advance to set the threshold value Qasref. FIG. 3 is an explanatory diagram showing an example of the threshold value setting map. As shown in the figure, the threshold value Qasref is set to increase as the coolant temperature Tw decreases. This is because the lower the coolant temperature Tw, the more difficult it is for the fuel injected from the port injection valve 25 and the in-cylinder injection valve 26 to vaporize, and the more likely the particulate matter emission amount (particulate number (PN)) is to increase.

[0029] When the integrated air quantity Qas is less than the threshold value Qasref in step S140, it is determined that suppression of particulate matter emission is required, and particulate matter suppression control (PN suppression control) is executed to control the engine 12 so as to suppress particulate matter emission (step S150), and the process returns to step S100. In the PN suppression control, for example, fuel of a target fuel injection quantity set so that the output of the engine 12 (intake air quantity Qa) is within a range equal to or less than an output Pe2 (intake air quantity Qa2) slightly larger than the output Pe1 (intake air quantity Qa1) for catalyst warm-up is injected twice (for example, once in the first half and once in the second half of the intake stroke) from the in-cylinder injection valve 26 during the intake stroke. Thereby, the injection length of the fuel injected from the in-cylinder injection valve 26 can be shortened to suppress the fuel from hitting the cylinder bore 31 and the piston 32, and the atomization time of this fuel can be ensured. As a result, the emission amount (number of particulate matters) of particulate matter can be suppressed. FIG. 4 is an explanatory diagram showing an example of the relationship among the output of the engine 12, the injection method from the in-cylinder injection valve 26, and the emission amount of particulate matter. The inventors obtained the results of FIG. 4 through analysis and the like. From FIG. 4, it can be understood that when fuel is injected from the in-cylinder injection valve 26 in two stages during the intake stroke, the emission amount of particulate matter is less than when fuel is injected from the in-cylinder injection valve 26 in one stage during the intake stroke and one stage during the compression stroke, and the difference between the two becomes more prominent as the output of the engine 12 increases.

[0030] When the integrated air quantity Qas is equal to or greater than the threshold value Qasref in step S140, normal control is started (step S160), and this routine is terminated. In the normal control, fuel consumption, fuel dilution, emissions, drivability, etc. are prioritized compared to catalyst warm-up control and PN suppression control.

[0031] In the engine device 10 of the embodiment described above, after the engine 12 has completed starting, when warm-up of the catalyst 35a is required, catalyst warm-up control is executed, and when warm-up of the catalyst 35a is not required and suppression of particulate matter emission is required, PN suppression control is executed. That is, when both warm-up of the catalyst 35a and suppression of particulate matter emission are required, the catalyst warm-up control is executed with priority over the PN suppression control. Thereby, it is possible to suppress an increase in the time required for activation of the catalyst 35a.

[0032] In the engine device 10 of the embodiment, the integrated air quantity Qas used for determining whether or not suppression of particulate matter emission is required is calculated as an integrated value of the intake air quantity Qa from the start of starting (cranking start) of the engine 12. However, the integrated air quantity Qas may be calculated as an integrated value after the rotational speed Ne of the engine 12 reaches a threshold value Neref or more when starting the engine 12.

[0033] In the engine device 10 of the embodiment, the threshold value Qasref used for determining whether or not suppression of particulate matter emission is required is set based on the coolant water temperature Tw of the engine 12. However, the threshold value Qasref may be set based on the starting coolant water temperature Twst which is the coolant water temperature Tw at the start of starting of the engine 12. In this case, the coolant water temperature Tw in the threshold value setting map of FIG. 3 may be replaced with the starting coolant water temperature Twst and used.

[0034] In the engine device 10 of the embodiment, the catalyst warm-up control and the PN suppression control have been described for the case of the in-cylinder injection mode, but the case of the common injection mode can be considered in the same way. In the case of the common injection mode, compared with the case of the in-cylinder injection mode, the injection amount from the in-cylinder injection valve 26 becomes smaller, so that the emission amount of particulate matter can be suppressed more. In this case, the fuel may be injected all at once from the port injection valve 25, or the fuel may be injected in a plurality of times.

[0035] In the engine device 10 of the embodiment, the engine 12 is provided with the port injection valve 25 and the in-cylinder injection valve 26. However, it may be provided with only either one of the port injection valve 25 and the in-cylinder injection valve 26. When having only the port injection valve 25, in the PN suppression control, it is conceivable to inject fuel from the port injection valve 25 in multiple times. Further, in this case, even before the start of the engine 12 is completed, when suppression of the emission of particulate matter is required, the PN suppression control may be executed.

[0036] The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problems will be described. In the embodiment, the engine 12 corresponds to the "engine", the catalyst 35a corresponds to the "catalyst", and the electronic control unit 70 corresponds to the "control device".

[0037] Note that the correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problems is an example for specifically explaining the form for implementing the invention described in the column of means for solving the problems in the embodiment. Therefore, it does not limit the elements of the invention described in the column of means for solving the problems. That is, the interpretation of the invention described in the column of means for solving the problems should be made based on the description in that column, and the embodiment is merely a specific example of the invention described in the column of means for solving the problems.

[0038] As described above, the embodiments for implementing the present invention have been described using examples. However, the present invention is not limited to such examples, and it goes without saying that the present invention can be implemented in various forms without departing from the gist of the present invention.

Industrial Applicability

[0039] The present invention can be used in the manufacturing industry of engine devices and the like.

Explanation of Reference Numerals

[0040] 10 Engine device, 12 Engine, 14 Crankshaft, 14a Crank position sensor, 15 Water temperature sensor, 16 Cam position sensor, 22 Air cleaner, 23 Intake pipe, 23a Air flow meter, 23t Temperature sensor, 24 Throttle valve, 24a Throttle position sensor, 25 Port injection valve, 26 In-cylinder injection valve, 28 Intake valve, 29 Combustion chamber, 30 Spark plug, 31 Cylinder bore, 32 Piston, 33 Exhaust valve, 34 Exhaust pipe, 35 Purification device, 35a Catalyst, 37 Front air-fuel ratio sensor, 38 Rear air-fuel ratio sensor, 50 Fuel supply device, 51 Fuel tank, 51t Fuel temperature sensor, 52 Feed pump, 52a Rotation speed sensor, 53 Low-pressure supply pipe, 53p Fuel pressure sensor, 54 Check valve, 55 Relief pipe, 56 Relief valve, 57 High-pressure pump, 57a Solenoid valve, 57b Check valve, 57c Plunger, 58 High-pressure supply pipe, 58p Fuel pressure sensor, 70 Electronic control unit, 71 CPU, 72 ROM, 73 RAM, 74 Flash memory.

Claims

Claim 1 An engine, a catalyst for purifying the exhaust gas of the engine, a control device for controlling the engine, and an engine device comprising: wherein the control device after the start of the engine is completed, when warm-up of the catalyst is required, executes catalyst warm-up control for controlling the engine so as to promote warm-up of the catalyst, and when warm-up of the catalyst is not required and suppression of particulate matter emissions is required, executes particulate matter suppression control for controlling the engine so as to suppress emissions of the particulate matter. An engine device.

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