JP2021110284A - Control device of internal combustion engine - Google Patents

Abstract

To provide a control device of an internal combustion engine for suppressing an increase of a manufacturing cost when suppressing vibration at a cylinder pause operation.SOLUTION: A control device of an internal combustion engine which can pause a part of cylinders out of all the cylinders comprises a control unit for performing rotation variation control for varying a rotational speed of the internal combustion engine at a cylinder pause operation and a steady operation of the internal combustion engine. The control unit increases and decreases a fuel injection amount of an operating cylinder at the execution of the rotation variation control. Preferably, the fuel injection amount of the operating cylinder is increased and decreased so that an output of the internal combustion engine becomes constant at the execution of the rotation variation control. By this constitution, a vibration frequency of the internal combustion engine may temporarily pass a resonance frequency, however, the vibration frequency is not maintained at the resonance frequency.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to a control device for an internal combustion engine, and more particularly to a control device applied to a multi-cylinder internal combustion engine capable of suspending a part of all cylinders.

A multi-cylinder internal combustion engine capable of suspending some of all cylinders in order to improve fuel efficiency, exhaust emissions, etc. is known (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2005-67591

When cylinder deactivation is performed, the number of operating cylinders decreases, so the vibration of the internal combustion engine tends to increase. On the other hand, conventionally, vibration is suppressed by adding a vibration damping device such as a damper device to the internal combustion engine. However, in this case, the manufacturing cost increases due to the addition of parts.

Therefore, the present disclosure was conceived in view of such circumstances, and an object of the present disclosure is to provide a control device for an internal combustion engine capable of suppressing an increase in manufacturing cost when suppressing vibration during cylinder deactivation.

According to one aspect of the present disclosure
An internal combustion engine control device that can suspend some of all cylinders.
Provided is a control device for an internal combustion engine, which comprises a control unit configured to execute rotation fluctuation control for changing the rotation speed of the internal combustion engine during cylinder deactivation operation and steady operation of the internal combustion engine. Will be done.

Preferably, the control unit increases or decreases the fuel injection amount in the operating cylinder when the rotation fluctuation control is executed.

Preferably, the control unit increases or decreases the fuel injection amount in the operating cylinder so that the output of the internal combustion engine becomes constant when the rotation fluctuation control is executed.

According to the present disclosure, it is possible to suppress an increase in manufacturing cost when suppressing vibration during cylinder deactivation operation.

It is the schematic of the internal combustion engine which concerns on embodiment. It is a map which shows the operating area of an internal combustion engine. It is a time chart which shows the transition of each value during execution of rotation fluctuation control. It is a flowchart which shows the routine of control.

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be noted that the present disclosure is not limited to the following embodiments.

FIG. 1 is a schematic view of an internal combustion engine according to an embodiment of the present disclosure. The internal combustion engine (also referred to as an engine) 1 is a multi-cylinder compression ignition type internal combustion engine mounted on a vehicle (not shown), and specifically, an in-line 4-cylinder diesel engine. The vehicle is a large vehicle, specifically a cab-over type truck. However, the type, type, application, etc. of the vehicle and the internal combustion engine are not particularly limited. For example, the vehicle may be a small vehicle such as a passenger car, and the engine may be a spark-ignition internal combustion engine (for example, a gasoline engine or a natural gas engine). There may be.

The engine may be mounted on a moving body other than a vehicle, for example, a ship, a construction machine, or an industrial machine. Further, the engine does not have to be mounted on a moving body, and may be a stationary engine.

The engine 1 includes an engine main body 2 and an intake passage 3 and an exhaust passage 4 connected to the engine main body 2. The engine body 2 includes structural parts such as a cylinder head, a cylinder block, and a crankcase, and movable parts such as a piston, a crankshaft, an intake valve, and an exhaust valve housed therein. The intake and exhaust flows are indicated by white arrows and black arrows, respectively.

Each cylinder is provided with a fuel injection valve, that is, an injector 7, which injects fuel directly into the cylinder 9.

The intake passage 3 is mainly defined by an intake manifold 10 connected to the engine body 2 (particularly a cylinder head) and an intake pipe 11 connected to the upstream end of the intake manifold 10. The intake pipe 11 is provided with an air cleaner 12, an air flow meter 13, a turbocharger 14 compressor 14C, an intercooler 15, and an electronically controlled intake throttle valve 16 in this order from the upstream side. The air flow meter 13 is a sensor for detecting the intake air amount (intake flow rate) per unit time of the engine 1.

The exhaust passage 4 is mainly defined by an exhaust manifold 20 connected to the engine body 2 (particularly a cylinder head) and an exhaust pipe 21 arranged on the downstream side of the exhaust manifold 20. A turbine 14T of a turbocharger 14 is provided between the exhaust pipe 21 or the exhaust manifold 20 and the exhaust pipe 21. A plurality of catalysts are provided in the exhaust pipe 21 on the downstream side of the turbine 14T. In the present embodiment, the oxidation catalyst 22, the particulate filter 23, the selective reduction NOx catalyst 24, and the ammonia oxidation catalyst 26 are provided in this order from the upstream side. An addition valve 25 for adding urea water is provided on the upstream side of the NOx catalyst 24. Since the particulate filter 23 is a continuously regenerating filter with a catalyst, it is included in the catalyst here.

The engine 1 also includes an external EGR30. The external EGR device 30 is installed outside the engine body 2 in order to recirculate a part of the exhaust gas (EGR gas) in the exhaust passage 4 (particularly in the exhaust manifold 20) into the intake passage 3 (particularly in the intake manifold 10). The EGR passage 31 is provided, an EGR cooler 32 for cooling the EGR gas flowing through the EGR passage 31, and an EGR valve 33 for adjusting the flow rate of the EGR gas.

The engine 1 includes four cylinders # 1 to # 4. Two of them, specifically # 2 and 3, are considered to be constantly operating cylinders that are always operated when the engine is running. The remaining two cylinders, specifically # 1 and # 4, are considered to be pauseable cylinders that can be paused when the engine is running.

The combustion order of each cylinder is # 1, 3, 4, 2. Since the operating cylinder and the deactivated cylinder appear alternately during the cylinder deactivation operation, it is advantageous in terms of vibration suppression. It should be noted that which cylinder number is used for the constantly operating cylinder and the suspendable cylinder is arbitrary.

Here, cylinder deactivation means to stop the fuel injection of the deactivated cylinder and to stop the operation of at least one of the intake valve and the exhaust valve (collectively referred to as a valve) to maintain the valve closed state. In this embodiment, the operation of both the intake valve and the exhaust valve is stopped.

The engine 1 is provided with a valve stop device 50 configured to selectively stop the intake valves and exhaust valves of the stoptable cylinders # 1 and # 4. The valve deactivation device 50 includes a plurality of valve deactivation mechanisms 51 provided for the intake valve and the exhaust valve of each cylinder. The configuration of these valve suspension mechanisms 51 is the same. As for the configuration of the valve suspension mechanism 51, various ones including known ones can be adopted. For example, one that switches the presence or absence of driving force transmission from the camshaft to the valve by flood control, one equipped with an electromagnetic actuator that drives the valve, and the like can be adopted.

The vehicle is provided with a control device for controlling the engine 1. The control device includes a control unit, a circuit element (circuitry), or an electronic control unit (referred to as an ECU (Electronic Control Unit)) 100 that forms a controller. The ECU 100 includes the above-mentioned air flow meter 13, a rotation speed sensor 40 for detecting the rotation speed of the engine (specifically, the number of revolutions per minute (rpm)), and an accelerator for detecting the accelerator opening degree. The opening sensor 41 is electrically connected.

The ECU 100 is configured to control the injector 7, the intake throttle valve 16, the addition valve 25, the EGR valve 33, and the valve suspension mechanism 51 based on the parameters related to the engine operating state detected by these sensors and the like.

The ECU 100 determines the engine torque required by the driver according to a predetermined map (may be a function; the same applies hereinafter) based on the engine speed Ne and the accelerator opening Ac detected by the rotation speed sensor 40 and the accelerator opening sensor 41, respectively. The required torque Tr, which is a value, is calculated. The required torque Tr can also be calculated based only on the accelerator opening degree Ac. The required torque Tr is a value that correlates with the load of the engine, in other words, is an index value that represents the load of the engine. The ECU 100 calculates a fuel injection amount Q such that a torque equal to the required torque Tr is actually output from the engine, and injects a fuel equal to the fuel injection amount Q from the injector 7. For example, the ECU 100 calculates the fuel injection amount Q according to a predetermined map based on the detected engine speed Ne and the calculated required torque Tr.

The ECU 100 determines whether to perform cylinder deactivation operation (or cylinder reduction operation) or all cylinder operation according to a map stored in advance as shown in FIG. In the figure, the line a shows the maximum required torque Trmax for each rotation, and the line b shows the threshold value Trs for each rotation. The region on the low load side where the required torque Tr is equal to or less than the threshold value Trs is the predetermined cylinder deactivation region A (indicated by hatching).

When the engine operating state defined by the engine speed Ne and the required torque Tr is in the cylinder deactivation region A, that is, when Tr ≤ Trs, the ECU 100 operates the constantly operating cylinders # 2 and 3 and the deactivated cylinder # 1. Executes cylinder deactivation operation to deactivate ， 4. At this time, in the suspendable cylinders # 1 and 4, the ECU 100 turns off the injector 7 to stop the fuel injection, and also stops the operation of the intake valve and the exhaust valve by the valve suspension mechanism 51 to close them. maintain.

On the other hand, the region on the high load side where the required torque Tr is larger than the threshold value Trs is the predetermined all cylinder region B. When the engine operating state defined by the engine speed Ne and the required torque Tr is in the all cylinder region B, that is, when Tr> Trs, the ECU 100 sets the constantly operating cylinders # 2 and 3 and the restable cylinders # 1 and 4. Execute all cylinder operation to operate together. At this time, the ECU 100 turns on the injectors 7 of all cylinders at each injection timing to execute fuel injection, and opens and closes the intake valve and the exhaust valve of the suspendable cylinders # 1 and 4 by the valve suspension mechanism 51.

By the way, when the cylinder deactivation operation is performed, the number of operating cylinders decreases from 4 cylinders to 2 cylinders, so that the engine vibration tends to increase. On the other hand, conventionally, vibration is suppressed by adding a vibration damping device such as a damper device to the engine, but in this case, the manufacturing cost increases due to the addition of parts.

Therefore, in the present embodiment, vibration during cylinder deactivation is suppressed by devising control instead of adding such parts. As a result, it is possible to suitably suppress an increase in manufacturing cost when suppressing vibration during cylinder deactivation operation.

The ECU 100 of the present embodiment is configured to execute rotation fluctuation control that fluctuates the rotation speed (specifically, the engine rotation speed) of the engine during cylinder deactivation operation and steady operation of the engine.

Engine vibration increases during cylinder deactivation. In addition, when the engine is idle or when the vehicle is cruising at high speed (cruise), the engine is in steady operation. At this time, the engine load is usually low, so the cylinder is deactivated and the engine speed is almost the same. It is kept constant. Therefore, the engine continuously generates vibrations having a large amplitude and a substantially constant frequency.

The greater the vibration of the engine, the worse the ride quality of the vehicle that the driver feels. Moreover, when the vibration frequency of the engine matches the natural vibration frequency of the cab of the vehicle, the cab resonates and the ride quality felt by the driver is further deteriorated. The driver is likely to feel such resonance only in the operating state where there is originally little vibration. If the vibration frequency of the engine is maintained at the natural vibration frequency of the cab, that is, the resonance frequency, the resonance of the cab is also maintained, which may be a pain for the driver.

On the other hand, according to the present embodiment, the engine speed is finely and periodically fluctuated during the cylinder deactivation operation and the steady operation. Therefore, although the vibration frequency of the engine may temporarily pass through the resonance frequency, the vibration frequency of the engine is not maintained at the resonance frequency. Therefore, it is possible to suppress the resonance of the cab and suppress the deterioration of the riding comfort of the vehicle.

Hereinafter, an example of rotation fluctuation control will be described. FIG. 3 shows changes in the engine output P, the engine speed Ne, the fuel injection amount Q, and the fuel injection timing θ during the execution of the rotation fluctuation control. The horizontal axis is time t. The amount of change in each value is exaggerated. The fuel injection timing θ is calculated according to a predetermined map based on the engine speed Ne and the required torque Tr, as in the fuel injection amount Q.

The target output Pt is the engine output corresponding to the driver's operation (that is, requested by the driver) during the cylinder deactivation operation and the steady operation. Similarly, the engine speed corresponding to the driver's operation is set to the target speed Net, the fuel injection amount is set to the target injection amount Qt, and the fuel injection time is set to the target injection time θt.

The fuel injection amount Q in the operating cylinders (constantly operating cylinders # 2 and 3) is periodically changed around the target injection amount Qt, and the engine speed Ne is also periodically changed around the target speed Net accordingly. NS. At this time, the fluctuation of the fuel injection amount Q and the fluctuation of the engine speed Ne are in a substantially opposite phase relationship. That is, for example, as shown at time t1, when the engine speed Ne exceeds the target speed Net, the fuel injection amount Q is the correction amount ΔQ (> 0) corresponding to the difference ΔNe (= Ne−Net> 0). Is reduced from the target injection amount Qt. That is, Q = Qt−ΔQ. In this way, the engine speed Ne is lowered toward the target speed Net. The relationship between the rotation difference ΔNe and the correction amount ΔQ can be stored in the ECU 100 in advance in a map format, and the ECU 100 can calculate the correction amount ΔQ corresponding to the rotation difference ΔNe according to this map.

After that, as shown at time t2, when the engine speed Ne undershoots and falls below the target speed Net, the fuel injection amount Q is increased by the correction amount ΔQ (<0) according to the difference ΔNe (<0). It is increased from the target injection amount Qt. That is, Q = Qt−ΔQ. In this way, the engine speed Ne rises toward the target speed Net, then overshoots, and becomes the same as the time t1.

It should be noted that such an increase / decrease in the fuel injection amount Q can be executed, for example, by adding a correction accelerator opening that periodically changes around zero to the accelerator opening corresponding to the amount of depression of the accelerator pedal by the driver. can. As a result, even if the driver keeps the accelerator opening constant as usual, the fuel injection amount Q and the engine speed Ne can be finely increased or decreased during that time.

On the other hand, at this time, the engine output P is maintained substantially constant at the target output Pt so that the driver does not notice the fluctuation of the engine speed Ne as much as possible. In other words, the magnitude of the correction amount ΔQ of the fuel injection amount is set so as to be so.

In the present embodiment, the fuel injection timing θ is also changed around the target injection timing θt in order to help maintain the engine output P at the target output Pt. At this time, the fluctuation cycle of the fuel injection timing θ may be shorter than the fluctuation cycle of the fuel injection amount Q and the engine speed Ne, as shown in the illustrated example. As a result, the engine output P can be finely adjusted using the fuel injection timing θ, and can be suitably maintained at the target output Pt.

When the engine is a spark-ignition type internal combustion engine, the ignition timing is changed instead of the fuel injection timing.

Next, the control routine in this embodiment will be described with reference to FIG. The illustrated routine is repeatedly executed by the ECU 100 every predetermined calculation cycle τ (for example, 720 ° CA).

First, in step S101, the ECU 100 determines whether or not the engine operating state defined by the engine speed Ne and the required torque Tr is in the cylinder deactivation region A as shown in FIG.

When in the cylinder deactivation region A, the ECU 100 proceeds to step S102 to execute the cylinder deactivation operation. Then, in step S103, it is determined whether or not the engine is in steady operation. For example, the ECU 100 determines that the engine is in steady operation when the fluctuation amounts of the engine speed Ne and the required torque Tr within a predetermined time are each equal to or less than a predetermined value. The fuel injection amount or the accelerator opening may be used instead of the required torque Tr.

When it is determined that the steady operation is in progress, the ECU 100 proceeds to step S104, executes the rotation fluctuation control described above, and ends the routine.

On the other hand, if the ECU 100 determines in step S101 that it is not in the cylinder deactivation region A, that is, if it determines that it is in the all cylinder region B, the ECU 100 proceeds to step S105 and executes all cylinder operation. Then, in step S106, the rotation fluctuation control is stopped (that is, not executed) and the routine is terminated. In this way, during all-cylinder operation, all cylinders are operated, the vibration of the engine is small, and there is no risk of resonance, so that the rotation fluctuation control is stopped.

Further, even if the ECU 100 determines in step S103 that the steady operation is not in progress, the ECU 100 proceeds to step S106 to stop the rotation fluctuation control. In this case, it is considered that the engine speed is changing and the vibration frequency of the engine is not maintained at the resonance frequency.

Incidentally, as a prior art, there is known a technique in which the cylinder number of a deactivated cylinder is changed for each engine cycle in order to suppress vibration during cylinder deactivated operation. However, in this case, all cylinders must be deactivated, and a valve deactivation mechanism must be provided for all cylinders. Therefore, the manufacturing cost increases due to the increase in the number of parts. Control is also complicated. According to this embodiment, there is an advantage that vibration can be suppressed by a simpler configuration and control than this conventional technique.

Although the embodiments of the present disclosure have been described in detail above, various other embodiments and modifications of the present disclosure can be considered.

(1) For example, the vehicle may be an ordinary passenger car. In this case, the engine speed is fluctuated so that the vibration frequency of the engine is not maintained at the natural vibration frequency of the body of the vehicle.

(2) In the above embodiment, the total number of cylinders (four) is bisected into a constantly operating cylinder and a restable cylinder, but it does not necessarily have to be bisected. The number of suspensionable cylinders may be larger or smaller than the number of constantly operating cylinders.

The embodiments of the present disclosure are not limited to the above-described embodiments, and all modifications, applications, and equivalents included in the ideas of the present disclosure defined by the claims are included in the present disclosure. Therefore, this disclosure should not be construed in a limited way and may be applied to any other technique that falls within the scope of the ideas of this disclosure.

1 Internal combustion engine (engine)
7 Injector 50 Valve deactivation device 51 Valve deactivation mechanism 100 Electronic control unit (ECU)

Claims (3)

An internal combustion engine control device that can suspend some of all cylinders.
A control device for an internal combustion engine, which comprises a control unit configured to execute rotation fluctuation control for varying the rotation speed of the internal combustion engine during cylinder deactivation operation and steady operation of the internal combustion engine. The control unit is a control device for an internal combustion engine, characterized in that the fuel injection amount in the operating cylinder is increased or decreased when the rotation fluctuation control is executed. The control device for an internal combustion engine according to claim 1 or 2, wherein the control unit increases or decreases the fuel injection amount in the operating cylinder so that the output of the internal combustion engine becomes constant when the rotation fluctuation control is executed.

Images