JP2007247615A - Intake control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an intake control device capable of improving idling stability even if either one of throttle valves of an internal combustion engine provided with a plurality of independent cylinder groups fails. <P>SOLUTION: This intake control device for an internal combustion engine 1 is provided with a plurality of cylinder groups LB, RB, is provided with an intake air passage 3 for each of the cylinder group LB, RB, has a throttle valve 5 and an idling speed control valve 11 arranged in the intake air passage, includes a communication path 20 connecting the intake air passages, and is provided with a control means controlling the idling speed control valve of the cylinder group to which normal throttle valve belongs and controlling the idling speed control valve of the cylinder group to which the failed throttle valve belongs too when one of the throttle valves fails. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an intake air control device that improves idle stability of an internal combustion engine. More specifically, in an internal combustion engine having a plurality of independent cylinder groups and a throttle valve and an idle speed control valve provided for each cylinder group, idle stability when one of the throttle valves fails The present invention relates to an intake air control device that improves the efficiency.

  2. Description of the Related Art Conventionally, an internal combustion engine having a plurality of independent cylinder groups, and a structure in which a throttle valve is arranged by providing an independent intake passage for each cylinder group is known. However, if one of the throttle valves fails in this structure, the intake air amount (intake amount) decreases and the output decreases, and a sudden deceleration or shock unexpected by the driver may occur. is there. Thus, for example, Patent Document 1 proposes a throttle control device that maintains the output by controlling the normal throttle valve to the open side when the throttle valve fails and increasing the amount of intake air that passes through the normal throttle valve. According to this throttle control device, it is possible to suppress a decrease in output of the entire internal combustion engine when the throttle valve fails, and to improve drive feeling.

  By the way, with respect to an internal combustion engine having a plurality of independent cylinder groups, consideration must be given to achieving idle stability. Idle stability is a performance that keeps the rotational speed (rotational speed) of an internal combustion engine at idling constant. Conventionally, there have been a plurality of proposals for techniques for improving idle stability. For example, a bypass pipe is provided so as to bypass the throttle valve, and an idle speed control valve (hereinafter referred to as an ISC valve) for controlling the intake amount during idling is provided in the bypass pipe. The structure is well known. By adopting such a structure, the ISC valve can be feedback controlled based on the rotational speed of the internal combustion engine, so that the idle stability of the internal combustion engine can be improved. For example, an air amount control device for an internal combustion engine disclosed in Patent Document 2 is provided with a pressure sensor in each cylinder group, and the detection results of the pressure sensor are compared. Then, the opening degree of the idle speed control valve of the high pressure side intake system is corrected to be smaller than that of the low pressure side intake system. This avoids intake air interference between cylinder groups and improves idle stability.

JP-A-9-195831 JP-A-6-336842

  However, Patent Document 1 merely discloses a fail-safe technique for controlling a normal throttle valve opening side to suppress a decrease in output of the entire internal combustion engine when any throttle valve fails. No consideration is given to idle stability when the throttle valve fails. On the other hand, Patent Document 2 discloses a technique for achieving idle stability when the throttle valve is operating normally, and does not take into account the response when the throttle valve fails. Therefore, even if both patent documents are taken into consideration, when any throttle valve fails in an internal combustion engine having a plurality of independent cylinder groups, the idle stability cannot be improved.

  Furthermore, in an internal combustion engine having a plurality of independent cylinder groups as described above, for example, a gas line for supplying blow-by gas may be provided so as to connect the intake passages of the respective cylinder groups. Thus, when the structure which connects an intake passage is provided, since the difference in the intake air amount between the cylinder groups acts as pressure fluctuation, it becomes difficult to perform idle control. In the past, in consideration of these points, it has been said that sufficient consideration has not been given to idle stability when any throttle valve fails in an internal combustion engine having a plurality of independent cylinder groups. Is the actual situation.

  Therefore, an object of the present invention is to provide an intake control device that can improve idle stability even when any throttle valve of an internal combustion engine having a plurality of independent cylinder groups fails. is there.

  The above object is provided with a plurality of cylinder groups, each of which is provided with an intake passage, a throttle valve and an idle speed control valve are disposed in the intake passage, and a connection for connecting the intake passages to each other. An intake air control apparatus for an internal combustion engine having a passage, which controls an idle speed control valve of a cylinder group to which a normal throttle valve belongs when a failure occurs in any of the throttle valves, and This is achieved by an intake air control device for an internal combustion engine, characterized by comprising control means for controlling an idle speed control valve of a cylinder group to which a throttle valve in which a failure has occurred belongs.

  According to the present invention, when any one of the throttle valves fails, the control means uses not only the normal idle speed control valve on the throttle valve side but also the idle speed control valve on the failed throttle valve side. Therefore, the idle stability can be reliably improved.

  In addition, an intake air amount detection means for detecting the intake air amount is provided for each of the cylinder groups, and the control means detects whether the normal cylinder group is abnormal or not based on an output signal from the intake air amount detection means. It is preferable to execute the cooperative control so that the intake air amount with a certain cylinder group matches.

  Further, the control means determines that a difference in intake air amount between the normal side cylinder group and the abnormal side cylinder group is predetermined after a lapse of a predetermined time from the start of operation only in the cylinder group to which the normal throttle valve belongs. When the value is equal to or greater than the value, the cooperative control may be started.

  ADVANTAGE OF THE INVENTION According to this invention, even if it is a case where any throttle valve of the internal combustion engine provided with two or more independent cylinder groups fails, the intake control device which can aim at the improvement of idle stability can be provided.

  Hereinafter, an internal combustion engine control apparatus according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing an internal combustion engine 1 to which an intake air control device of an embodiment is applied. The internal combustion engine 1 is a so-called V-type engine, and independent banks LB and RB are formed on the left and right. Four cylinders 8 are arranged in each of the left bank LB and the right bank RB to form a cylinder group. Each cylinder group is provided with an individual intake passage 3. In the following description, the components common to the left and right banks are distinguished by attaching the symbol R to the configuration belonging to the right bank and the component L belonging to the left bank.

  The left and right banks are formed symmetrically. The configuration on the right bank RB side will be described. The atmosphere (air) from which dust or the like has been filtered by the air cleaner 2R is supplied to the cylinder group side by the intake passage 3R. The downstream end of the intake passage 3R is connected to a surge tank 6R, and this surge tank 6R is connected to each cylinder 8R via an intake manifold 7R. An air flow meter 4R serving as an air flow rate detecting means is disposed in the vicinity of the downstream side of the air cleaner 2R so that the intake air amount (air amount) flowing through the intake passage 3R can be detected. The air flow rate detection means may be a device that directly detects the flow rate of intake air, such as the air flow meter 4R illustrated, or a pressure sensor that detects air pressure. When a pressure sensor is employed as the air flow rate detection means, the intake air flow rate may be converted from the air pressure.

  Further, the bypass pipe 10R is branched from the upstream intake passage 3R where the throttle valve 5R is disposed, and the other end of the bypass pipe 10R is connected to the balance pipe 12R. The balance pipe 12R is branched and connected to each cylinder 8R. An idle speed control valve 11 (hereinafter referred to as ISC valve 11) is arranged in the middle of the bypass pipe 10R. The opposite left bank LB is formed in the same manner.

  Further, the internal combustion engine 1 is provided with a blow-by line 20 for returning blow-by gas generated during operation to the intake passages 3R and 3L. The blow-by line 20 serves as a communication passage that connects the intake passage 3R and the intake passage 3L.

  In the structure shown in FIG. 1, when any of the left and right throttle valves 5R and 5L fails, the negative pressure fluctuation between the left and right banks becomes large, especially during idle operation, making stable driving difficult. There is a case. The internal combustion engine 1 of the present embodiment incorporates an intake control device that copes with such a situation and improves idle stability. This intake control device adjusts the intake air amount so that the normal bank side can be smoothly driven using this ISC valve when the ISC valve belonging to the bank on the side where the throttle valve has failed is normal. Idle stability is improved as a whole internal combustion engine.

  FIG. 2 is a block diagram showing a configuration of a portion related to the intake air control device 30 applied to the internal combustion engine 1. The intake control device 30 includes left and right air flow meters 4R, 4L, throttle valves 5R, 5L, and ISC valves 11R, 11L. Further, an electronic control unit (hereinafter referred to as ECU) 31 for controlling driving of the throttle valves 5R and 5L and the ISC valves 11R and 11L is provided. Output signals from left and right air flow meters 4R and 4L that detect the intake air amount and output signals from sensors (not shown) that detect the rotational speed (NE) of the internal combustion engine are supplied to the ECU 31. The ECU 31 is connected via a bus 34 to a ROM 32 that stores a series of programs related to intake air control of the internal combustion engine 1 and a RAM 33 that provides a processing area. In addition, this ECU31 can simplify the structure of an intake air control apparatus by designing so that ECU of the internal combustion engine 1 side may be diverted. However, the ECU 31 for the intake control device may be prepared, or a dedicated ECU may be provided in each of the left and right banks.

  In FIG. 2, the ECU 31 confirms information on the intake air amount flowing in the left and right intake passages and the rotational speed NE of the internal combustion engine based on the output signals from the left and right air flow meters 4R, 4L, and performs control for idling stabilization. Functions as a means. More specifically, when the ECU 31 confirms that one of the throttle valves 5R and 5L has failed, the ISC valve of the cylinder group to which the normal throttle valve belongs is controlled, and the cylinder to which the failed throttle valve belongs is controlled. By controlling the ISC valves of the group together, the idle controllability is improved and the operation stability is improved.

  By the way, when a failure of the throttle valve is confirmed, the driving of the bank to which the throttle valve belongs is generally stopped and the operation of the internal combustion engine is continued in the one-bank state. That is, for example, when a failure of the throttle valve 5L in the left bank LB is confirmed, the driving on the left bank LB side is stopped, and the internal combustion engine is operated in a so-called one-bank state in which only the normal right bank RB is driven. It was common in the past. However, since the piston connected to the crankshaft moves in the cylinder of the left bank LB, an intake flow is generated and the in-cylinder pressure changes. Here, since the intake passage 3R and the intake passage 3L are connected by the blow-by line 20, the in-cylinder pressure of the normal right bank RB is affected and fluctuates. As a result, the rotational speed (NE) of the internal combustion engine fluctuated and the idling operation became unstable. On the other hand, when the malfunctioning ISC valve on the throttle valve side is normal, the ECU 31 of the present embodiment device also adjusts the opening of the ISC valve to suppress the intake air amount difference between the left and right banks. As a result, the normal bank is smoothly driven to improve idleness.

  FIG. 3 is a flowchart showing an example of a routine that is executed by the ECU 31 to improve idle stability when the throttle valve of either the left or right bank RB or LB is confirmed to be defective. For example, the ECU 31 starts this routine when it is confirmed that the ignition of the internal combustion engine 1 is turned on.

  First, the ECU 31 monitors whether or not a failure (fail) has occurred in the left and right throttle valves 5R and 5L (S11). If any throttle valve is operating normally, normal control is maintained (S12). ) Continue monitoring.

  On the other hand, when the ECU 31 confirms that either of the throttle valves 5R and 5L has failed in step 11 (S11), the ECU 31 switches to the operation only on the bank (referred to as a normal bank) side including the normal throttle valve (S13). . In that case, the opening degree of the throttle valve (TA) on the bank (referred to as an abnormal bank) side including the throttle valve in which the failure has occurred is fixed. Then, it is confirmed that the ISC valves of both banks are operating normally (S14), and the idle control for improving the idle stability by adjusting the opening degree of both ISC valves is executed (S15). . Thus, when the ISC valve belonging to the abnormal bank operates normally, the intake air fluctuation on the normal side is suppressed by adjusting the opening degree of both ISC valves to promote idle stability.

  Further, the ECU 31 checks whether or not the difference in intake air amount between the left and right banks is equal to or greater than a predetermined value after a predetermined time from the start of the one-bank operation (S16). When the difference in intake air amount between the left and right banks is greater than or equal to a predetermined value, the negative pressure fluctuation between the banks is large, and the rotational speed of the internal combustion engine fluctuates, resulting in unstable operation during idling. Therefore, when the difference in intake air amount between the left and right banks is larger than a predetermined value, the cooperative control shown in step 17 below is executed. On the other hand, when the difference between the intake air amounts of the left and right banks is smaller than the predetermined value, the idle stability is improved by the idle control executed in step 15 above. Therefore, in this case, the processing by this routine is terminated.

  On the other hand, when the intake air amount difference between the left and right banks is equal to or greater than a predetermined value, cooperative control is executed (S17). In this cooperative control, the ISC valve of the bank on the side with a large intake amount is driven in a direction to throttle a certain amount, and the ISC valve of the opposite bank with a small amount of intake is driven in the same direction to open. In this way, the left and right ISC valves are driven at the same time so that a large difference in intake air amount is efficiently reduced and matched. As a result, idle stability can be improved. When executing cooperative control, it is preferable that the opening degree of the throttle valve (TA) of the normal bank is fixed.

  When the ECU 31 confirms that the difference in intake air amount between the left and right banks is smaller than a predetermined value and the idle stability is improved in the next step 18 (S18), the processing by this routine is terminated. However, there may be a case where the intake air amount difference cannot be made smaller than a predetermined value even if the above cooperative control is executed. In this case, it is difficult to improve idle stability even if the ISC valve is further controlled. Therefore, in this case, the left and right ISC valves are fixed, the opening degree of the throttle valve (TA) of the normal bank is adjusted, idle speed control (ISC control) is executed to achieve idle stability, and this routine is executed. The process ends.

  As described above, when the ISC valve belonging to the failure bank operates normally, the ECU 31 functioning as the control means executes the high idle control combined with the ISC valve of the normal bank using this ISC valve. The internal combustion engine of the present embodiment can improve idle stability even when a failure occurs in the throttle valve.

  FIG. 4 is a time chart showing the state of cooperative control executed for idling stabilization in the intake air control apparatus of the embodiment in comparison with the conventional one. As shown on the upper side, when a failure occurs in any of the throttle valves (TA), the one-bank operation is started after a predetermined time. When the one-bank operation is performed in this way, the fluctuation amount of the rotation speed (NE) becomes large due to the difference in intake air amount (pressure difference) generated between the left and right banks, and the idle state becomes unstable.

  If the difference in intake air amount between the left and right banks does not decrease even after a predetermined time has elapsed after the one-bank operation is started, cooperative control is entered. This coordinated control simultaneously drives the left and right ISC valves in opposite directions, as outlined above. FIG. 4 shows an example in which the opening degree of the ISC valve on the normal bank side is large and the opening degree of the ISC valve on the abnormal bank side is small. In this case, as indicated by the symbol CR in FIG. 4, when the cooperative control is executed, the opening degree of the ISC valve on the normal bank side is corrected by a fixed amount, while the ISC valve on the abnormal bank side is opened by the same amount. The opening is corrected in the direction. As a result, as shown in the lowermost stage of FIG. 4, the difference between the intake air amounts between the left and right banks is eliminated, and a matching state can be formed. On the other hand, since the deviation (intake amount difference) cannot be eliminated in the conventional case, the idle state becomes unstable. An internal combustion engine provided with an intake control device that performs the above-described cooperative control can improve idle stability even if a failure occurs in the throttle valve.

  FIG. 4 shows a case where only the throttle valve fails and the difference in intake air amount between banks can be reduced with the left and right ISC valves. As described above with reference to the flowchart of FIG. 3, when there is another cause along with the failure of the throttle valve, the intake air amount difference may not be reduced even by cooperative control. In this case, as described in step 19 of FIG. 3, the idle speed control is performed by further adjusting the throttle valve of the normal bank.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

It is the figure shown about the internal combustion engine to which the intake control device of an Example is applied. It is the block diagram which showed the structure of the part which concerns on the intake control device applied to the internal combustion engine. 7 is a flowchart illustrating an example of a routine that is executed by the ECU 31 to improve idle stability when a throttle valve in either of the left and right banks RB and LB is confirmed to be defective. It is the time chart which showed the mode of the cooperative control performed for idle stabilization with the intake control device of an Example compared with the past.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Air cleaner 3 Intake passage 4 Air flow meter (intake air amount detection means)
5 Throttle valve 6 Surge tank 8 Cylinder 10 Bypass pipe 11 ISC valve (idle speed control valve)
20 blow-by line 30 intake control device 31 ECU (control means)
LB left bank RB right bank

Claims (3)

A plurality of cylinder groups are provided, an intake passage is provided for each cylinder group, a throttle valve and an idle speed control valve are disposed in the intake passage, and a communication passage connecting the intake passages is provided. An intake control device for an internal combustion engine,
When a failure occurs in any of the throttle valves, the idle rotation speed control valve of the cylinder group to which the normal throttle valve belongs is controlled, and the idle rotation speed control valve of the cylinder group to which the failed throttle valve belongs. An intake control device for an internal combustion engine, characterized by comprising control means for controlling the engine. An intake air amount detection means for detecting the intake air amount is provided for each of the cylinder groups,
The control means performs cooperative control based on an output signal from the intake air amount detection means so that intake air amounts of a normal cylinder group and an abnormal cylinder group coincide with each other. Item 6. An intake control device for an internal combustion engine according to Item 1. The control means has a difference in intake air amount between a normal cylinder group and an abnormal cylinder group equal to or greater than a predetermined value after a predetermined time has elapsed after starting operation only with the cylinder group to which the normal throttle valve belongs. 3. The intake control apparatus for an internal combustion engine according to claim 2, wherein the cooperative control is started when

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