JP2014227882A - Engine cylinder number control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deterioration of performance caused by an increase of intake pressure pulsation and a change of a gas flow in a cylinder when an engine is switched to a partial cylinder operation from a full-cylinder operation.SOLUTION: Passages 15a, 15d are extended from branches 4a, 4d of an intake manifold 4, merged with a bypass passage 15, and connected to an upstream side of a throttle valve 9 of an intake pipe 8. Changeover valves 16a, 16d are interposed at a branched part of the passages 15a, 15d of the branches 4a, 4d, and made to communicate with an exhaust pipe 11 side of cylinders of the branches 4a, 4d at a full-cylinder operation. At a partial cylinder operation, an exhaust port of the cylinder is switched so as to communicate with the upstream side of the throttle valve 9 of the intake pipe 8 via the bypass passage 15 from the passages 15a, 15d. By this constitution, fuel economy can be improved while preventing the deterioration of performance caused by an increase of intake pressure pulsation and a change of a gas flow in the cylinder by making air discharged from an operation-stopped cylinder by pumping flow back to the upstream side of the throttle valve 9.

Description

  The present invention relates to an engine cylinder number control device for controlling the number of operating cylinders by performing fuel cut on some cylinders of an engine to stop the operation.

  In recent years, in an engine mounted on a vehicle such as an automobile, a cylinder number control engine in which the number of operating cylinders is variable may be employed in order to simultaneously satisfy the conflicting requirements of high output and economy. This cylinder number control engine stops the fuel supply and introduces exhaust or air to some of the cylinders during a predetermined partial load operation that does not require a high output such as a low load range. Or by keeping the intake / exhaust valve open, the operation of the corresponding cylinder is stopped to reduce fuel consumption.

  For example, Patent Document 1 discloses a cylinder number control engine that performs partial cylinder operation by stopping fuel supply to some cylinders at a light load. The cylinder number control engine of Patent Document 1 separates an intake manifold and an exhaust manifold into a cylinder group on the operating side and a cylinder group on the idle side, and has a return passage for circulating air from the exhaust manifold of the cylinder on the idle side to the intake manifold. In addition, a control valve that bypasses the catalyst during partial cylinder operation is provided in the idle exhaust pipe upstream of the catalyst to prevent air from flowing into the catalyst when switching from full cylinder operation to partial cylinder operation. At the time of switching from operation to all-cylinder operation, low temperature air is prevented from being mixed into the high temperature exhaust from the operating cylinder to prevent the exhaust temperature from decreasing, and the purification performance of the catalyst is prevented from decreasing. .

Japanese Patent Publication No. 61-5528

  However, in the technique disclosed in Patent Document 1, a shut-off valve is provided to divide the intake manifold downstream of the throttle valve into a stop intake manifold and an operation intake manifold. Pressure pulsation may occur in order to block the flow of fresh air into the side cylinder group.

  Similarly, even when the intake / exhaust valve is opened and the cylinder is stopped, air is sucked only into the combustion cylinder, so that there is a stroke in which air is not sucked out from the intake manifold, which may increase pressure pulsation in the intake manifold. There is. As a result, the gas flow in the cylinder differs between the full-cylinder operation and the partial cylinder operation, and the performance of the tumble flow may be reduced, leading to a decrease in performance.

  The present invention has been made in view of the above circumstances, and when switching from full-cylinder operation to partial cylinder operation, an engine cylinder capable of preventing performance degradation due to an increase in intake pressure pulsation or a change in gas flow in the cylinder. The object is to provide a number control device.

  The cylinder number control device for an engine according to the present invention is a cylinder number control device for an engine that controls the number of operating cylinders by performing a fuel cut on a part of the cylinders of the engine to stop the operation. A recirculation passage that connects the exhaust port of the cylinder to be connected to the intake system, a first passage system that connects the exhaust port of the cylinder to be deactivated to an exhaust passage common to all cylinders, A switching valve that selectively switches the exhaust port of the target cylinder to the second passage system that communicates with the recirculation passage, and exhaust of the cylinder that is the target of suspension of operation via the switching valve during all cylinder operation A port is communicated with the first passage system, and when the fuel of the cylinder to be deactivated is cut, the exhaust port of the cylinder to be deactivated is connected to the second passage system via the switching valve. And a control unit for communicating to.

  According to the present invention, when switching from full cylinder operation to partial cylinder operation, an increase in intake pressure pulsation and a change in gas flow in the cylinder can be suppressed, and fuel consumption can be improved while preventing performance degradation. it can.

Schematic configuration diagram of the engine system Flow chart of cylinder number control processing

Embodiments of the present invention will be described below with reference to the drawings.
In FIG. 1, reference numeral 1 denotes an engine having a plurality of cylinders. In FIG. 1, a four-cylinder engine having four cylinders is shown. An intake manifold 3 that communicates with the intake port of each cylinder and an exhaust manifold 4 that communicates with the exhaust port of each cylinder are attached to the cylinder head 2 of the engine 1. In addition, an injector 5 is attached to the cylinder head 2 immediately upstream of each intake port, and an ignition plug 6 that exposes the ignition part to the combustion chamber is attached.

  In the intake manifold 3, branches 3 a, 3 b, 3 c, 3 d communicating with the intake ports of the respective cylinders are gathered on the upstream side and communicated with the air chamber 7. An intake pipe 8 is connected to the upstream side of the air chamber 7, and the intake pipe 8 communicates with an air cleaner 10. A throttle valve 9 that is driven to open and close by a throttle actuator 9a made of a step motor or the like is interposed in the middle of the intake pipe 8.

  On the other hand, in the exhaust manifold 4, branches 4 a, 4 b, 4 c and 4 d communicating with the exhaust ports of the respective cylinders are gathered downstream and communicated with the exhaust pipe 11, and the exhaust pipe 11 is connected to the muffler 13. An exhaust pipe 11 on the upstream side of the muffler 13 is provided with a catalytic converter 12 for purifying exhaust gas.

  Here, of the branches 4a to 4d of the exhaust manifold 4, a passage communicating with the intake system is extended from a branch communicating with the exhaust ports of some cylinders. In the present embodiment, of the four cylinders, passages 15a and 15d communicating with the intake side are extended from the branches 4a and 4d of the two cylinders. These passages 15 a and 15 d are joined to the bypass passage 15, and the bypass passage 15 communicates with the upstream side of the throttle valve 9 of the intake pipe 8, whereby the exhaust port of the cylinder corresponding to the branches 4 a and 4 d of the exhaust manifold 4. And a circulation passage that connects the intake passage upstream of the throttle valve.

  Switching valves 16a and 16d for switching the passage systems after the branches 4a and 4d are interposed at the branch portions to which the passages 15a and 15d of the branches 4a and 4d are connected. The switching valves 16a and 16d are switched and driven by actuators 17a and 17d made of electromagnetic solenoids or the like. By these switching valves 16a and 16d, a first passage system communicating from the exhaust port of the corresponding cylinder to the exhaust pipe 11 side via the branches 4a and 4d, and branches 4a and 4d and passages 15a and 15d from the exhaust port of the relevant cylinder. The second passage system that communicates with the bypass passage 15 via the passage and communicates with the upstream side of the throttle valve 9 of the intake pipe 8 from the bypass passage 15 is selectively switched.

  Further, the engine 1 is provided with various sensors and switches for detecting the operating state. Typically, a throttle sensor 20 that detects the opening of the throttle valve 9, an intake air amount sensor 21 that measures the intake air amount, a crank angle sensor 22 that detects a crank angle for calculating the engine speed and control timing, An air-fuel ratio sensor 23 for detecting the air-fuel ratio from the exhaust component, and various other sensors (not shown) are arranged.

  Signals from these various sensors and switches are input to an engine control unit (ECU) 50 that controls the engine 1. The ECU 50 is an electronic control unit mainly composed of a microcomputer including a CPU, ROM, RAM, backup RAM, I / O interface, and the like, and includes various peripheral circuits. The ECU 50 is connected to an in-vehicle network such as a CAN (Controller Area Network) and communicates with other control units (not shown) that control automatic transmissions, brakes, suspensions, etc. Exchange.

  The ECU 50 passes through the throttle actuator 9a and the injector 5 based on the signal from the air-fuel ratio sensor 23 based on the signals from the sensors and various information acquired through the in-vehicle network according to the control program stored in the memory. Engine control such as air-fuel ratio control and ignition timing control via an igniter 30 for energizing and driving the spark plug 6 is performed.

  In this engine control, during the partial load operation of the engine 1, the number of cylinders is controlled by cutting off the fuel of some cylinders among a plurality of cylinders to improve fuel consumption. In the present embodiment, for four cylinders (two cylinders whose exhaust ports communicate with the branches 4a and 4d of the exhaust manifold 4) among the four cylinders, the fuel for these cylinders is cut to operate. I try to stop it. When the fuel of the deactivated cylinder is cut, the switching valves 16a and 16d are switched via the actuators 17a and 17d, and the exhaust port of the deactivated cylinder is communicated with the upstream side of the throttle valve 9 of the intake pipe 8 via the bypass passage 15. I have to.

  That is, at the time of all cylinder operation, the switching valves 16a and 16d are switched to close the passages 15a and 15d, the exhaust ports of all the cylinders are connected to the exhaust pipe 11, and the exhaust gas is purified by the catalytic converter 12 and discharged. On the other hand, during partial cylinder operation at a partial load, the combustion cylinder (working cylinder) is the same as during full cylinder operation. However, for the non-combustion cylinder (deactivation cylinder), the switching valves 16a and 16d are switched. The branches 4a and 4d of the exhaust manifold 4 are closed on the exhaust pipe 11 side, and the exhaust port is connected to the upstream side of the throttle valve 9 of the intake pipe 8 from the passages 15a and 15d via the bypass passage 15 and discharged by pumping. Air is circulated upstream of the throttle valve 9.

  In the partial cylinder operation by this fuel cut, the pump loss for the fuel cut cylinder is expected to be slightly larger than the cylinder stop by the intake / exhaust valve stoppage. Since the negative pressure in the manifold becomes weak, pump loss can be minimized as a result.

  In the present embodiment, the switching valves 16a and 16d are provided with the cylinders communicating with the branches 4a and 4d of the exhaust manifold 4 as cylinders to be deactivated. However, the present invention is not limited to this. The cylinders communicating with 4b and 4c may be deactivated cylinders, and the position and the number of cylinders of deactivated cylinders may be appropriately set in consideration of engine characteristics.

  The above cylinder number control is specifically executed as a program process of the ECU 50 shown in the flowchart of FIG. Hereinafter, the cylinder number control process will be described.

  In this cylinder number control process, in the first step S1, parameters representing the current engine operating state, for example, engine load such as engine speed, intake air amount and fuel injection amount, etc. are read. It is determined whether or not the operation mode is an operation mode in which the operation of some cylinders is suspended in the partial load operation state. For example, when the region based on the engine speed and the engine load is a preset low-load operation region, it is determined that the operation mode is one in which the operation of some cylinders is stopped. It is determined that the operation mode is set.

  If the current operation state is not the partial load operation state but the operation mode of all cylinder operation, the process proceeds from step S2 to step S3. In step S3, since the cylinders that are to be deactivated are also in a normal operation state, the switching valves 16a and 16d are switched to the exhaust side for the cylinders to be deactivated, the passages 15a and 15d are closed, and the exhaust ports are closed. The exhaust manifold 4 is communicated with the exhaust pipe 11 via the branches 4a and 4d. In step S4, a normal operation for operating all the cylinders is performed, and the process is exited.

  On the other hand, when the current operation state is a partial load operation state and is an operation mode in which the operation of some cylinders is stopped, the process proceeds from step S2 to step S4 to switch the switching valves 16a and 16d to the intake side. . That is, for the cylinder to be deactivated, the exhaust pipe 11 side of the branch 4a, 4d of the exhaust manifold 4 is closed, and the exhaust port is upstream of the throttle valve 9 of the intake pipe 8 from the passages 15a, 15d via the bypass passage 15. Communicate to the side. In step S6, fuel is cut from the cylinders to be deactivated and fuel is supplied to the remaining cylinders to burn the partial cylinders.

  In this partial cylinder operation, fuel consumption can be suppressed by cutting the fuel of the deactivated cylinder, the activated cylinder can be operated efficiently at a relatively high load, and the fuel efficiency of the entire system can be improved. In addition, as in the conventional technique of stopping the operation of the cylinder by stopping the operation of the intake / exhaust valve, there occurs a stroke in which only the combustion cylinder sucks air and the air is not sucked out from the intake manifold, and the pressure in the intake manifold There is no increase in pulsation, and fuel efficiency can be improved while suppressing a decrease in performance due to a change in gas flow in the cylinder.

  Further, since the switching valve 16a, 16d closes the exhaust pipe 11 side from the exhaust port of the deactivated cylinder, the intake air that does not contribute to combustion does not flow into the exhaust system, and the air-fuel ratio is disturbed to the lean side and the air-fuel ratio controllability Is not disturbed, or the exhaust temperature is lowered by low-temperature air and the function of the catalyst is not inhibited. Furthermore, a complicated and expensive mechanism for switching the drive of the intake / exhaust valve that operates at high speed to stop the operation of the cylinder is not required, and the passage can be switched by a simple switching valve, thereby suppressing an increase in cost. be able to.

DESCRIPTION OF SYMBOLS 1 Engine 4 Exhaust manifold 8 Intake pipe 9 Throttle valve 11 Exhaust pipe 15 Bypass passage 15a, 15d Passage 16a, 16d Switching valve 50 Engine control unit

Claims (3)

In the engine cylinder number control device that controls the number of operating cylinders by performing fuel cut on some cylinders of the engine to stop the operation,
A circulation passage connecting the exhaust port of the cylinder to be deactivated and an intake system;
A first passage system for communicating the exhaust port of the cylinder to be deactivated with a common exhaust passage for all cylinders, and a second passage system for communicating the exhaust port of the cylinder with an operation suspension with the circulation passage A switching valve for selectively switching the passage system;
During all-cylinder operation, the exhaust port of the cylinder to be deactivated is communicated with the first passage system via the switching valve, and when the fuel of the cylinder to be deactivated is cut, the switching valve is And a control unit for communicating an exhaust port of the cylinder to be deactivated via the second passage system.   2. The engine cylinder number control device according to claim 1, wherein the circulation passage is a passage connecting an exhaust port of a cylinder to be deactivated and an intake passage upstream of a throttle valve. 3.   3. The engine cylinder number control device according to claim 1, wherein the switching valve is provided in a predetermined branch to which the circulation passage of the exhaust manifold is connected.

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