JP7652132B2 - Engine Control Unit - Google Patents

Description

The present invention relates to an engine control device.

Filters that capture exhaust particulates from engines are known. It is also known that such filters can be regenerated by raising the temperature of the filter by retarding the ignition timing of the engine or by using a lean air-fuel ratio (see, for example, Patent Document 1).

JP 2020-012404 A

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

The present invention aims to provide an engine control device that suppresses rattling and muffled noise while also preventing a deterioration in fuel efficiency.

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 comprising: a determination unit that determines whether or not there is at least one of a temperature increase request to increase the temperature of the filter by retarding ignition timing of the engine, and a regeneration request to regenerate 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, and when both the temperature increase request and the regeneration request are made, This can be achieved by an engine control device that controls the engine torque to be lower and the engine speed to be higher for the same engine output when there is a temperature increase request but no regeneration request, and when there is a temperature increase request but no regeneration request, controls the engine torque to be lower and the engine speed to be higher for the same engine output when there is no temperature increase request but no regeneration request, and when there is no temperature increase request but there is a regeneration request, controls the engine torque to be lower and the engine speed to be higher for the same engine output when there is no temperature increase request but no regeneration request.

The present invention provides an engine control device that suppresses rattling and booming noise while also preventing deterioration of fuel economy.

FIG. 1 is a schematic diagram of an engine. FIG. 2 is a flowchart showing an example of engine operation control. FIG. 3 is an example of a map that defines the first line L1 to the fourth line L4.

[General configuration of engine]
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.

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

Each intake port 20a constituting 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.

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.

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

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 the cells with the upstream ends of the GPF 42 open, and passes through the porous walls between adjacent cells, capturing PM (exhaust particulate matter) in the exhaust gas. 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, if the engine 10 is a diesel engine, a DPF (Diesel Particulate Filter) is provided instead of the GPF 42.

The ECU (Electronic Control Unit) 100 is an electronic control unit that performs control processing related to the engine 10. The ECU 100 is mainly composed of a computer including a CPU (Central Processing Unit), and volatile and non-volatile memory such as RAM (Random Access Memory) and ROM (Read Only Memory). The ECU 100 executes various control processes related to 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 an engine control device, and functionally realizes a determination unit and a control unit, which will be described in detail later.

The ECU 100 is connected to 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, and receives output signals from these various sensors. 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 amount of intake air. 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.

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 volume. The ECU 100 calculates the target speed and target load based on the accelerator opening, and controls the fuel injection amount, intake air volume, and ignition timing so that the engine speed and load become the target speed and target load, respectively.

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 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 fuel components are intentionally generated along 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 from a sensor, and executes temperature rise control when the temperature of the GPF 42 is below a predetermined value.

The ECU 100 also executes regeneration control to burn the soot accumulated in the GPF 42. As 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 since the completion of the regeneration control, based on the differential pressure before and after the GPF 42, or by other known methods.

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 executing such control causes the engine torque to fluctuate. This fluctuation in engine torque causes an increase in rattle and muffled noise. In particular, when both the temperature rise control and the regeneration control are executed simultaneously, the fluctuation in engine torque is greatest, and the rattle and muffled noise become louder. For this reason, in order to suppress rattle and muffled noise when the temperature rise control and the regeneration control are executed simultaneously, it is possible to constantly significantly reduce the engine torque.

However, if the engine torque is constantly reduced significantly even when there is no temperature increase or regeneration request, the engine speed must be controlled to be higher to ensure engine output, which reduces fuel efficiency. 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:

[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.

The ECU 100 determines whether there is a request to increase the temperature of the GPF 42 (step S1). If the answer is No in step S1, the ECU 100 determines whether there is a request to regenerate the GPF 42 (step S2). If the answer is No in step S2, i.e., 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 multiple 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).

If the answer is Yes in step S2, i.e., if there is a regeneration request but no temperature increase request, the ECU 100 controls the operating point of the engine 10 on the second line L2 described below (step S4).

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, i.e., there is a temperature increase request but no regeneration request, the ECU 100 controls the operating point of the engine 10 on the third line L3 described later (step S6).

If step S5 is Yes, i.e., if there are both a temperature increase request and a regeneration request, the ECU 100 controls the operating point of the engine 10 on the fourth line L4 described below (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.

Figure 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, Figure 3 also shows the optimum fuel economy line BL and the equal power line PL. The first line L1 is shown as a dotted line, the second line L2 as a dashed line, the third line L3 as a dashed line, the fourth line L4 as a dashed line, the optimum fuel economy line BL as a solid line, and the equal power line PL as a thick line.

The optimal 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 engine torque and engine speed that can suppress rattles and booming noises 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 and simulation results.

As shown in Figure 3, the first line L1 to the fourth line L4 are further away from the optimal fuel efficiency line BL. Also, 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 same order. Here, the points P1 to P4 are further away from the optimal fuel efficiency line BL, and the fuel efficiency deteriorates in the order of points P1 to P4.

For example, when the required output of engine 10 is the output defined by the equal output line PL shown in FIG. 3, ECU 100 controls the operating point of 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 in engine torque when the operating point of 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. This causes rattling and muffled noise to increase in this order. The first line L1 to the fourth line L4 are defined to correspond to this.

Therefore, when there is neither a temperature increase request nor a regeneration request, 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.

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 muffled noise while also preventing a deterioration in fuel efficiency.

In the above embodiment, an example was described in which temperature rise control causes greater fluctuations in engine torque and louder rattles and booming noises than regeneration control, and temperature rise control is controlled to reduce engine torque to a greater extent than regeneration control, but this is not limited to the above. For example, if regeneration control causes greater fluctuations in engine torque than temperature rise control, regeneration control is controlled to reduce engine torque to a greater extent than temperature rise control.

In the above embodiment, it is assumed that both the temperature rise control and the regeneration control are performed simultaneously, but this is not limited to the above, and the regeneration control may be performed after the temperature rise control is completed. In this case, it is preferable to control the operating point of the engine 10 to be on the third line L3 while the temperature rise control is being performed, and to control the operating point of the engine 10 to be on the second line L2 while the re-control is being performed after the temperature rise control is completed.

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 this is not limiting. For example, the contents of the above embodiment can also be applied to engine control devices mounted on motorcycles, etc., and engine control devices mounted on things other than vehicles, such as ships and construction machinery.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to these specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention as described in the claims.

10 Engine 100 ECU (engine control device, determination unit, control unit)

Claims (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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