Engine Control Unit

Abstract

To provide an engine control device which prevents aggravation of fuel economy while suppressing rattling and muffled sound.SOLUTION: An engine control device which is applied to an engine mounted with a filter collecting particulate matters in exhaust comprises: a determination section which determines whether or not at least either a temperature increase request to increase a temperature of the filter through delaying an ignition timing of the engine or a regeneration request to regenerate the filter through engine operation with a lean air-fuel ratio is made; and a control section which makes engine torque and an engine rotation speed with respect to identical engine output lower and higher respectively when a determination result of the determination section is affirmative than the engine torque and the engine rotation speed when the determination result is negative.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] There is known a filter that collects exhaust particulates from an engine. It is also known that such a filter can be regenerated by raising the temperature by retarding the ignition timing of the engine or by using a lean air-fuel ratio of the engine (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-012404 A Summary of the Invention [Problem to be solved by the invention]

[0004] The temperature rise and regeneration of the filter as described above may cause the engine torque to fluctuate, resulting in increased rattling and booming noise. One possible solution to this problem is to reduce the engine torque and keep the engine speed high. However, constantly keeping the engine speed high results in poor fuel economy.

[0005] SUMMARY OF THE PRESENT EMBODIMENTS Accordingly, an object of the present invention is to provide an engine control device that suppresses rattling and booming noise while also suppressing deterioration of fuel economy. [Means for solving the problem]

[0006] The above object is to provide an engine control device that is applied to an engine provided with a filter that captures particulate matter in exhaust gas, the control device including: a determination unit that determines whether or not there is at least one of a temperature increase request for increasing the temperature of the filter by retarding an ignition timing of the engine and a regeneration request for regenerating the filter by a lean air-fuel ratio of the engine; and a control unit that, when a positive determination is made by the determination unit, controls the torque of the engine to be lower and the rotation speed of the engine to be higher for the same output of the engine than when a negative determination is made by the determination unit. When there are both the temperature increase request and the regeneration request, the control unit controls the engine torque to be lower and the engine speed to be higher for the same output of the engine than when there is a temperature increase request and there is no regeneration request; when there is a temperature increase request and there is no regeneration request, the control unit controls the engine torque to be lower and the engine speed to be higher for the same output of the engine than when there is no temperature increase request and there is no regeneration request; and when there is no temperature increase request and there is a regeneration request, the control unit controls the engine torque to be lower and the engine speed to be higher for the same output of the engine than when there is no temperature increase request and there is no regeneration request. This can be achieved by the engine control device. Effect of the Invention

[0007] According to the present invention, it is possible to provide an engine control device that suppresses rattling and booming noise while also suppressing deterioration of fuel economy. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of the engine. [Diagram 2] FIG. 2 is a flowchart showing an example of engine operation control. [Diagram 3] FIG. 3 is an example of a map that defines the first line L1 to the fourth line L4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [Engine outline] FIG. 1 is a schematic diagram of an engine 10. The engine 10 is mounted on an internal combustion engine vehicle as a drive source, but is not limited thereto, and may be applied to a hybrid vehicle equipped with an engine and a motor as a drive source. The engine 10 is a gasoline engine, but is not limited thereto, and may be a diesel engine. Each cylinder 12 of the engine 10 is provided with a piston 13. The piston 13 is connected to a crankshaft 15, which is an output shaft of the engine 10, via a connecting rod 14. The reciprocating motion of the piston 13 is converted into the rotational motion of the crankshaft 15 by the connecting rod 14.

[0010] A combustion chamber 16 is formed above the piston 13 in each cylinder 12, and a spark plug 18 that ignites the mixture of fuel and air is attached to this combustion chamber 16. The timing of ignition of the mixture by this spark plug 18 is adjusted by an igniter 19 provided above the spark plug 18.

[0011] Each intake port 20a constituting a part of the intake passage 20 is provided with a port injection valve 22 for injecting fuel into the intake port 20a for each cylinder 12. The engine 10 is provided with an in-cylinder injection valve 17 for injecting fuel into each combustion chamber 16. The engine 10 is provided with both the in-cylinder injection valve 17 and the port injection valve 22, but is not limited to this and may be an engine provided with only one of them.

[0012] The combustion chamber 16 is connected to an intake passage 20 and an exhaust passage 21. The intake passage 20 is provided with a throttle valve 23 that adjusts the amount of air introduced into the combustion chamber 16.

[0013] An air-fuel ratio sensor 35, a three-way catalyst 41, and a GPF (Gasoline Particulate Filter) 42 are provided in the exhaust passage 21 in this order from the upstream side. The three-way catalyst 41 contains a catalytic metal such as platinum (Pt), palladium (Pd), or rhodium (Rh), has an oxygen storage capacity, and purifies NOx, HC, and CO.

[0014] The GPF 42 is a porous ceramic structure in which the front and rear ends of adjacent cells are alternately sealed. Exhaust gas flows into cells with open upstream ends of the GPF 42 and passes through the porous walls between adjacent cells, at which time PM (exhaust particulate matter) in the exhaust gas is captured. The GPF 42 also carries a precious metal such as platinum, which promotes the oxidation reaction of the accumulated PM during regeneration control. The GPF 42 is an example of a filter. Therefore, for example, when the engine 10 is a diesel engine, a DPF (Diesel Particulate Filter) is provided instead of the GPF 42.

[0015] The ECU (Electronic Control Unit) 100 is an electronic control unit that performs control processing for the engine 10. The ECU 100 is mainly composed of a computer including a CPU (Central Processing Unit) and volatile and non-volatile memories such as a RAM (Random Access Memory) and a ROM (Read Only Memory). The ECU 100 executes various control processes for the engine 10 on the CPU by executing programs installed in the memory. Various sensors are connected to the ECU 100, which will be described in detail later. The ECU 100 is an example of a control device for an engine, and functionally realizes a determination unit and a control unit, which will be described in detail later.

[0016] An accelerator opening sensor 31, a water temperature sensor 32, an air flow meter 33, a crank angle sensor 34, and an air-fuel ratio sensor 35 are connected to the ECU 100, and output signals from these various sensors are input. The accelerator opening sensor 31 detects the accelerator opening. The water temperature sensor 32 detects the temperature of the cooling water that cools the engine 10. The air flow meter 33 detects the intake air amount. The crank angle sensor 34 detects the rotation angle of the crankshaft 15. The air-fuel ratio sensor 35 is provided in the exhaust passage 21 upstream of the three-way catalyst 41, and detects the air-fuel ratio of the exhaust gas flowing into the three-way catalyst 41.

[0017] The ECU 100 calculates the engine speed based on the detection value of the crank angle sensor 34, and calculates the engine load based on the engine speed and the intake air amount. The ECU 100 calculates the target engine speed and target load based on the accelerator opening, and controls the fuel injection amount, intake air amount, and ignition timing so that the engine speed and load become the target engine speed and target load, respectively.

[0018] The ECU 100 executes temperature rise control to raise the temperature of the GPF 42 in order to increase the soot adsorption efficiency of the GPF 42. As the temperature rise control, the ECU 100 executes control to correct the ignition timing of the mixture to the retard side compared to normal operation. By retarding the ignition timing, unburned components of the fuel are intentionally generated together with oxygen, and these are supplied to the GPF 42 to raise the temperature of the GPF 42. The ECU 100 estimates the temperature of the GPF 42 or acquires it by a sensor, and executes the temperature rise control when the temperature of the GPF 42 is equal to or lower than a predetermined value.

[0019] The ECU 100 also executes regeneration control to burn soot accumulated in the GPF 42. As the regeneration control, the ECU 100 executes control to feed back the air-fuel ratio of the mixture supplied to the combustion chamber 16 to a lean air-fuel ratio that is leaner than the theoretical air-fuel ratio based on the detection result of the air-fuel ratio sensor 35. By making the air-fuel ratio of the mixture lean, oxygen is left over in the combustion in the combustion chamber 16, and as a result, oxygen is supplied to the GPF 42, and the soot accumulated in the GPF 42 can be burned by the supplied oxygen. The ECU 100 estimates the amount of soot accumulated in the GPF 42, and executes a regeneration request when the amount of accumulation becomes equal to or greater than a predetermined value. The method of estimating the amount of soot accumulated in the GPF 42 may be, for example, based on the driving history of the engine 10 from the completion of the regeneration control, based on the pressure difference before and after the GPF 42, or by other known methods.

[0020] As described above, the temperature rise control and regeneration control of the GPF 42 change the operating state of the engine 10, such as retarding the ignition timing or using a lean air-fuel ratio, and when such control is performed, the engine torque fluctuates. This fluctuation in engine torque increases rattling and muffled noise. In particular, when both the temperature rise control and the regeneration control are performed simultaneously, the fluctuation in engine torque is the largest, and the rattling and muffled noise become louder. For this reason, in order to suppress rattling and muffled noise when the temperature rise control and the regeneration control are performed simultaneously, it is considered to constantly reduce the engine torque significantly.

[0021] However, if the engine torque is constantly reduced significantly even when there is no temperature increase or regeneration request, the engine speed must be increased accordingly to ensure engine output, which would result in poor fuel economy. Therefore, in this embodiment, the amount of engine torque reduction and the amount of engine speed increase are changed depending on whether there is a temperature increase or regeneration request, as follows:

[0022] [Engine operation control] Next, a description will be given of engine operation control executed by the ECU 100. Fig. 2 is a flow chart showing an example of engine operation control. This control is repeatedly executed while the ignition is on.

[0023] The ECU 100 determines whether or not there is a request to increase the temperature of the GPF 42 (step S1). If the result in step S1 is No, the ECU 100 determines whether or not there is a request to regenerate the GPF 42 (step S2). If the result in step S2 is No, that is, if there is neither a request to increase the temperature nor a request to regenerate, the ECU 100, which will be described in detail later, selects a first line L1 from among a plurality of lines that define the relationship between engine torque and engine speed, and controls the operating point of the engine 10 to be on the first line L1 (step S3).

[0024] If the answer is Yes in step S2, that is, if there is a regeneration request but no temperature increase request, the ECU 100 controls the operating point of the engine 10 on a second line L2 (to be described later) (step S4).

[0025] If the answer is Yes in step S1, the ECU 100 determines whether or not there is a regeneration request (step S5). If the answer is No in step S5, that is, if there is a temperature increase request but no regeneration request, the ECU 100 controls the operating point of the engine 10 on a third line L3 (described later) (step S6).

[0026] If the answer is Yes in step S5, that is, if there are both a temperature increase request and a regeneration request, the ECU 100 controls the operating point of the engine 10 on a fourth line L4 (described later) (step S7). The above-mentioned steps S1, S2, and S5 are examples of processing executed by the determination unit, and steps S3, S4, S6, and S7 are examples of processing executed by the engine control unit.

[0027] Fig. 3 is an example of a map that defines the first line L1 to the fourth line L4. The vertical axis indicates engine torque, and the horizontal axis indicates engine speed. In addition to the first line L1 to the fourth line L4, Fig. 3 also shows an optimum fuel consumption line BL and an equal power line PL. The first line L1 is shown by a dotted line, the second line L2 is shown by a dashed line, the third line L3 is shown by a dashed line, the fourth line L4 is shown by a broken line, the optimum fuel consumption line BL is shown by a solid line, and the equal power line PL is shown by a thick line.

[0028] The optimum fuel economy line BL is the line with the best fuel economy. The equal power line PL is the line with equal engine power. The first line L1 to the fourth line L4 are lines for controlling the operation of the engine 10, which define the relationship between the engine torque and the engine speed that can suppress rattle and booming noise while also suppressing deterioration of fuel economy depending on the presence or absence of a temperature rise request and a regeneration request. These lines are defined in advance based on experimental results and simulation results.

[0029] As shown in Fig. 3, the first line L1 to the fourth line L4 are further away from the optimal fuel economy line BL in this order. If the intersections of the constant power line PL and the first line L1 to the fourth line L4 are points P1 to P4, respectively, the engine torque decreases in the order of points P1 to P4, but the engine speed increases in the order of points P1 to P4. Here, the points P1 to P4 are further away from the optimal fuel economy line BL in this order, and the fuel economy deteriorates in the order of points P1 to P4.

[0030] For example, when the required output of the engine 10 is the output defined by the equal output line PL shown in FIG. 3, the ECU 100 controls the operating point of the engine 10 to one of points P1 to P4 depending on the presence or absence of a temperature increase request and a regeneration request. Here, the fluctuation of the engine torque in a state where the operating point of the engine 10 in this embodiment is maintained at a predetermined operating point increases in the following order: when neither temperature increase control nor regeneration control is being executed, when only regeneration control is being executed, when only temperature increase control is being executed, and when both temperature increase control and regeneration control are being executed. As a result, rattling noise and muffled noise increase in this order. The first line L1 to the fourth line L4 are defined to correspond to this.

[0031] Therefore, when neither a temperature increase request nor a regeneration request is made, the ECU 100 controls the operating point of the engine 10 to point P1. When there is a regeneration request but no temperature increase request, the ECU 100 controls the operating point of the engine 10 to point P2. When there is a temperature increase request but no regeneration request, the ECU 100 controls the operating point of the engine 10 to point P3. When there are both a temperature increase request and a regeneration request, the ECU 100 controls the operating point of the engine 10 to point P4.

[0032] In this way, by switching the line for controlling the operating point of the engine 10 depending on the presence or absence of a temperature increase request and a regeneration request, it is possible to suppress rattling and booming noise while also suppressing deterioration of fuel economy.

[0033] In the above embodiment, the variation in engine torque is larger in the temperature rise control than in the regeneration control, resulting in louder rattling and booming noise, and the temperature rise control is controlled to reduce the engine torque more than the regeneration control, but this is not limiting. For example, when the variation in engine torque is larger in the regeneration control than in the temperature rise control, the regeneration control is controlled to reduce the engine torque more than the temperature rise control.

[0034] In the above embodiment, the explanation is given on the premise that both the temperature rise control and the regeneration control are performed simultaneously, but the present invention is not limited to this, and the regeneration control may be performed after the completion of the temperature rise control. In this case, it is preferable to control the operating point of the engine 10 to be on the third line L3 during the execution of the temperature rise control, and to control the operating point of the engine 10 to be on the second line L2 during the execution of the re-control after the completion of the temperature rise control.

[0035] In the above embodiment, the ECU 100 that controls the engine 10 mounted on a vehicle has been described as an example of an engine control device, but the present invention is not limited to this. For example, the contents of the above embodiment can be applied to engine control devices mounted on motorcycles and the like, and engine control devices mounted on things other than vehicles, such as ships and construction machines.

[0036] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims. [Explanation of symbols]

[0037] 10 Engine 100 ECU (engine control unit, judgment unit, control unit)

Claims

[Claim 1] An engine control device that is applied to an engine provided with a filter that collects particulate matter in exhaust gas, a determination unit that determines whether or not there is at least one of a temperature increase request for increasing the temperature of the filter by retarding the ignition timing of the engine and a regeneration request for regenerating the filter by a lean air-fuel ratio of the engine; a control unit that, when a positive determination is made by the determination unit, controls the torque of the engine to be lower and the rotation speed of the engine to be higher for the same output of the engine than when a negative determination is made by the determination unit, The control unit controls the engine torque to be lower and the engine speed to be higher for the same output of the engine when both the temperature increase request and the regeneration request are present, compared to when there is a temperature increase request and there is no regeneration request; when there is a temperature increase request and there is no regeneration request, the control unit controls the engine torque to be lower and the engine speed to be higher for the same output of the engine, compared to when there is no temperature increase request and there is no regeneration request; and when there is no temperature increase request and there is a regeneration request, the control unit controls the engine torque to be lower and the engine speed to be higher for the same output of the engine, compared to when there is no temperature increase request and there is no regeneration request.

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