JP2009250046A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain the generation of vibration caused by the lateral bending of an internal combustion engine body without increasing weight in the internal combustion engine body. <P>SOLUTION: This internal combustion engine has an ECU for setting the combustion pressure of at least one cylinder #3 and #4 positioned except for an end in the arranging direction of right/left banks in a state of being smaller than the combustion pressure of cylinders #1, #2, #5 and #6 positioned in the end in the arranging direction, to thereby reduce the lateral bending of an engine 100 generated by an impact of combustion (an explosion) in the cylinders #3, and #4. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an internal combustion engine, and more particularly to an internal combustion engine having a plurality of cylinders arranged in a pair of banks.

  The cylinder block of the V-type engine vibrates due to left / right bending (deformation of the cylinder block) caused by a combustion load. This vibration is transmitted to the vehicle body through an engine mount or the like and is transmitted as noise to the vehicle interior, so that the comfort in the vehicle interior is impaired.

  In order to suppress such vibration of the cylinder block, structures such as a bearing cap with a beam, a plate stiffener, and a ladder frame have been proposed.

  The bearing cap with beam is attached to the lower part of the bearing cap that is mounted on the cylinder block, or a beam that is integrated with or separate from the bearing cap to increase the rigidity of the bearing cap and the lower part of the cylinder block. It is to suppress. The plate stiffener is a plate-like rigidity enhancing member attached to the lower part of the cylinder block, and this also increases the lower rigidity of the cylinder block to suppress vibration of the cylinder block. In addition, the ladder frame is configured to increase the rigidity of the bearing cap portion and the lower portion of the cylinder block and to suppress vibration of the cylinder block by coupling the bearing caps in a ladder shape.

  By the way, when using these structures to suppress the vibration of the cylinder block (particularly the vibration that causes medium and high-frequency interior noise), it is necessary to greatly increase the rigidity of the cylinder block itself. There is a possibility of causing a significant increase in weight and an increase in manufacturing cost.

  On the other hand, recently, a technology has been proposed that suppresses the vibration of the cylinder block while suppressing the increase in cost and weight and suppresses the generation of medium and high-frequency vehicle interior noise caused by this vibration (for example, patents). Reference 1).

JP-A-6-185408

  The engine disclosed in Patent Document 1 includes a plate for reinforcing rigidity at the lower part of a cylinder block, and a dynamic damper that can absorb vibration of the cylinder block is attached to the plate for reinforcing rigidity.

  However, in Patent Document 1 as well, it is necessary to separately provide a plate for reinforcing rigidity and a dynamic damper in the engine, which may increase the weight of the entire engine.

  In order to suppress vibration and noise of the V-type engine, a method of reducing the combustion pressure only in the cylinder upstream in the rotation direction of the crank (Japanese Patent Laid-Open No. 6-193538) or suction of the cylinder adjacent to the end of the crankshaft. A method for limiting the amount of air (Japanese Utility Model Publication No. 6-14038) has also been proposed, but these techniques have little effect of suppressing the left / right bending of the engine (cylinder block) itself.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide an internal combustion engine capable of suppressing vibration caused by left-right bending without causing an increase in weight.

  In order to solve the above problems, an internal combustion engine of the present invention includes an internal combustion engine main body in which a plurality of cylinders are arranged in a pair of banks, and an end portion in the arrangement direction according to an operating state of the internal combustion engine main body. And setting means for setting a combustion pressure of at least one cylinder located in a position other than that of a cylinder located at an end in the arrangement direction.

  According to this, according to the operating state of the internal combustion engine body, the setting means calculates the combustion pressure of at least one cylinder located at a position other than the end in the arrangement direction in the internal combustion engine body arranged in a pair of banks. Since the pressure is lower than the combustion pressure of the cylinder located at the end, it is possible to reduce left-right bending of the engine caused by the impact of combustion (explosion) in the cylinder near the center in the arrangement direction. As a result, it is possible to suppress the occurrence of vibration due to the left / right bending of the internal combustion engine body without causing an increase in the weight of the internal combustion engine body.

  In this case, it further comprises parameter acquisition means for acquiring a parameter relating to the operating state of the internal combustion engine body, and the setting means determines whether or not to perform the setting based on the parameter acquired by the parameter acquisition means. can do. In such a case, the setting means performs the setting or not based on the parameter corresponding to the operating state of the internal combustion engine main body, so that it is possible to easily determine whether to perform the setting. .

  In this case, the parameter may be at least one of a load factor of the internal combustion engine body and a rotation speed of the internal combustion engine body. In such a case, since the setting is performed when there is a high possibility that left-right bending and vibration occur in the internal combustion engine body, such as when the load factor of the internal combustion engine body is large or when the rotational speed of the internal combustion engine body is large, Effective suppression of vibration can be realized.

  In the internal combustion engine of the present invention, in the setting, the fuel injection amount into at least one cylinder located at a position other than the end portion in the arrangement direction is set to a fuel injection amount into the cylinder located at the end portion in the arrangement direction. Can also be reduced. In such a case, it is possible to change the combustion pressure of the cylinder only by changing the fuel injection amount without separately providing a special device for controlling the combustion pressure.

  ADVANTAGE OF THE INVENTION According to this invention, the internal combustion engine which can suppress the vibration resulting from the right-and-left bending of an internal combustion engine main body can be provided, without causing a weight increase.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to FIGS.

  FIG. 1 is a schematic plan view of a V-type six-cylinder engine 100 as an internal combustion engine according to an embodiment of the present invention.

  The engine 100 includes a cylinder block 10, and left and right banks 12 and 14 that are inclined at a predetermined angle are provided on the upper portion of the cylinder block 10 as shown in FIG. 1. Three cylinder bores 16, 16, 16 are formed in the bank 12, and three cylinder bores 18, 18, 18 are formed in the bank 14. Each cylinder bore constitutes a cylinder. The engine 100 of the present embodiment has a first cylinder # 1 to a sixth cylinder # 6, of which the first cylinder # 1, the third cylinder # 3, and the fifth cylinder # 5 are on the same bank 12. Arranged (provided in series), the second cylinder # 2, the fourth cylinder # 4, and the sixth cylinder # 6 are arranged on the same bank 14 (provided in series).

  2 is a cross-sectional view taken along line AA in FIG. In addition, the BB line sectional view and CC line sectional view of FIG. 1 are also the same sectional views as FIG. As shown in FIG. 2, pistons 20 and 22 are inserted into the cylinder bores 16 and 18 so as to freely move up and down (slide).

  A crankshaft (not shown) is rotatably supported at the lower portion of the cylinder block 10, and the pistons 20 and 22 are connected to the crankshaft via connecting rods 24 and 26.

  As shown in FIG. 2, cylinder heads 30 and 32 are fastened to the upper portions of the banks 12 and 14 of the cylinder block 10, and the combustion chamber 34 is formed by the cylinder block 10, the pistons 20 and 22, and the cylinder heads 30 and 32. , 36 are configured. The intake ports 38A and 38B and the exhaust ports 40A and 40B are formed facing the upper portions of the combustion chambers 34 and 36, that is, the lower surfaces of the cylinder heads 30 and 32, respectively. The lower ends of the intake valves 42A and 42B and the exhaust valves 44A and 44B are positioned with respect to the intake ports 38A and 38B and the exhaust ports 40A and 40B.

  The intake valves 42A and 42B and the exhaust valves 44A and 44B are supported by the cylinder heads 30 and 32 so as to be movable along the axial direction of the valves, and close the intake ports 38A and 38B and the exhaust ports 40A and 40B. It is biased and supported in the direction of Further, intake camshafts 46A and 46B and exhaust camshafts 48A and 48B are rotatably supported on the cylinder heads 30 and 32, respectively. The intake camshafts 46A and 46B are respectively provided with intake cams 50A and 50B, and the exhaust camshafts 48A and 48B are respectively provided with exhaust cams 52A and 52B. The intake cams 50A and 50B and the exhaust cams 52A and 52B are in contact with the upper ends of the intake valves 42A and 42B and the exhaust valves 44A and 44B.

  Therefore, when the intake camshafts 46A and 46B and the exhaust camshafts 48A and 48B rotate, the intake cams 50A and 50B and the exhaust cams 52A and 52B move up and down the intake valves 42A and 42B and the exhaust valves 44A and 44B at a predetermined timing. Thus, the intake ports 38A, 38B and the exhaust ports 40A, 40B can be opened and closed, and the intake ports 38A, 38B and the combustion chambers 34, 36 can be communicated with the combustion chambers 34, 36 and the exhaust ports 40A, 40B, respectively. .

  Further, the valve operating mechanism including the intake valves 42A and 42B and the exhaust valves 44A and 44B is a variable intake valve operating mechanism that controls the intake valves 42A and 42B and the exhaust valves 44A and 44B at an optimum opening / closing timing according to the operating state. (VVT: Variable Valve Timing-intelligent) or an exhaust variable valve mechanism (the variable valve mechanism is not shown).

  A surge tank 56 is connected to the intake ports 38A, 38B of the cylinder heads 30, 32 via intake manifolds 54A, 54B, and one end of an intake pipe 58 is connected to the surge tank 56. The intake pipe 58 is provided with an electronic throttle device 60 having a throttle valve.

  On the other hand, a connecting pipe 68 is connected to the exhaust ports 40A and 40B via exhaust manifolds 64A and 64B and catalytic devices 66A and 66B. An exhaust pipe 70 to which a catalytic device 72 is attached is connected to the connecting pipe 68. It is connected.

  The cylinder heads 30 and 32 are respectively equipped with injectors 74A and 74B for injecting fuel (gasoline) directly into the combustion chambers 34 and 36, and delivery pipes 76A and 76B are connected to the injectors 74A and 74B. The delivery pipes 76A and 76B are supplied with a fuel having a predetermined pressure from a high-pressure fuel pump 78 provided on the cylinder head 30. In addition, spark plugs 80A and 80B for igniting the air-fuel mixture are mounted on the upper portions of the combustion chambers 34 and 36 of the cylinder heads 30 and 32, respectively.

  Further, an air flow sensor 69 is provided on the upstream side of the intake pipe 58. The air flow sensor 69 detects the amount of air passing through the intake pipe 58 (air intake amount). A crank angle sensor 71 for detecting the engine speed is provided in the cylinder block 10.

  FIG. 3 is a block diagram showing a control system of engine 100 shown in FIGS. 1 and 2. The control system of the engine 100 is configured around an electronic control unit (ECU) 120. The ECU 120 performs fuel injection timings of the injectors 74A and 74B via the high-pressure fuel pump 78 based on the engine rotation speed calculated based on the output of the crank angle sensor 71 and the engine load factor calculated based on the output of the airflow sensor 69. Control the fuel injection amount, and control the ignition timing of the spark plug. The engine load factor calculated based on the output of the air flow sensor 69 means the ratio of the current load to the total load. That is, the engine load factor can be regarded as, for example, the ratio of the current throttle opening to the throttle opening (100%) when fully open.

  Next, the left / right bending suppression control of the engine 100 by the ECU 120 will be described along the flowchart of FIG.

  In step S10 of FIG. 4, ECU 120 obtains a parameter (engine load factor) calculated based on the output of air flow sensor 69, and determines whether or not the engine load factor is within a predetermined range. Here, for example, 50% to 90% can be adopted as the predetermined range.

  If the determination in step S10 is affirmative, the process proceeds to step S12, and it is determined whether or not a parameter (engine speed) calculated based on the output of the crank angle sensor 71 is within a predetermined range. Here, as a predetermined range, 3500 rpm or more is employable, for example.

  If the determination in step S12 is affirmative (that is, if both determinations in steps S10 and S12 are affirmative), the process proceeds to step S14, and the third cylinder # 3 and the fourth cylinder # 4 in FIG. The fuel injection amount injected from the injectors 74A, 74B is high so that the fuel injection amount injected from the injectors 74A, 74B of the other cylinders (# 1, # 2, # 5, # 6) is smaller by a predetermined amount. The fuel pump 78 is set. The predetermined amount in this case can be about 10%. In this way, by reducing the fuel injection amount injected from the injectors 74A and 74B of the third cylinder # 3 and the fourth cylinder # 4 as compared with the other cylinders, the third cylinder # 3 and the fourth cylinder # 4 The combustion pressure can be made smaller than other cylinders.

  On the other hand, if the determination is negative in either step S10 or S12, the fuel injection amount (combustion pressure) in all cylinders # 1 to # 6 is uniformly maintained in step S16.

  In the present embodiment, as described above, when the determinations in steps S10 and S12 are affirmed and it is determined that the operating state of the engine 100 is in a higher load state than the normal state, the ECU 120 is connected in series. Since control is performed to reduce the combustion pressure of the cylinders (third cylinder # 3, fourth cylinder # 4) located at the center of the arranged cylinders, as shown in FIGS. 5 (a) and 5 (b). When the combustion pressure of the cylinders (# 3, # 4) located in the central part is high, the left / right bending of the engine caused by the explosion impact in those cylinders can be reduced.

  Thereafter, the above process is repeated until the determination in step S18 of FIG. 4 is affirmed. Then, when the engine is stopped and the determination in step S18 is affirmed, all the processes in FIG. 4 are completed.

  As described above, according to the present embodiment, the ECU 120 determines the combustion pressure of at least one cylinder located at the end other than the end in the arrangement direction (series direction) as the combustion pressure of the cylinder located at the end in the arrangement direction. Therefore, the left / right bending of the engine 100 as shown in FIGS. 5A and 5B caused by the impact of combustion (explosion) in the cylinder near the center in the arrangement direction can be reduced. Thereby, it is possible to suppress the vibration of the engine and suppress the deterioration of NV.

  Further, according to the present embodiment, the combustion pressure in the cylinder is changed by changing the fuel injection amount of the injectors 74A and 74B via the high-pressure fuel pump 78. Further, it is possible to prevent the engine from bending left and right without providing a bearing cap with a beam, a plate stiffener, a ladder frame, etc., or a plate for reinforcing rigidity or a dynamic damper. Therefore, vibration of the engine can be suppressed without causing an increase in the weight or cost of the engine 100.

  Further, according to the present embodiment, the ECU 120 changes the combustion pressures of the third and fourth cylinders # 3 and # 4 of the engine 100 based on parameters (engine load factor and engine speed) related to the operating state of the engine 100. Since (setting) is performed, the combustion pressure of each cylinder can be changed (set) easily and appropriately.

  In the above-described embodiment, whether to perform control for reducing the combustion pressures of the third and fourth cylinders # 3 and # 4 is determined based on two parameters (engine load factor and engine speed). However, the present invention is not limited to this, and the determination may be made based on either one. Further, it may be determined whether to perform control for reducing the combustion pressure using parameters other than the above two parameters.

  In the above embodiment, the case where the engine load factor is 50% to 90% and the engine speed is 3500 rpm or more has been described as the predetermined range of the parameter indicating the operating state of the engine. These predetermined ranges may be changed according to other elements. For example, in a vehicle equipped with an active suspension or the like, the predetermined range of each parameter may be changed according to which mode the mode pattern (normal, comfort, etc.) is set. Specifically, when the mode pattern is normal, similarly to the above, the predetermined range of the engine load factor is set to 50% to 90%, the predetermined range of the engine speed is set to 3500 rpm or more, and when the mode pattern is comfort, The predetermined range of the engine load factor can be set to 40% to 90%, and the predetermined range of the engine speed can be set to 3000 rpm or more. By executing such control, it is possible to produce a vehicle characteristic tailored to the user's preference.

  In this embodiment, the number of cylinders arranged in each of the left and right banks is three. However, the present invention is not limited to this. For example, the number of cylinders arranged in each of the left and right banks. May be 4 or more. As described above, when the number of cylinders is four or more, the combustion pressures of all the cylinders located at the end other than the end in the arrangement direction (series direction) may be set lower than those of the other cylinders. It is good also as making the combustion pressure of at least 1 cylinder located other than a part lower than another cylinder.

  The above-described embodiment is an example of a preferred embodiment of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention.

1 is a schematic plan view of an engine 100. FIG. It is the sectional view on the AA line of FIG. 2 is a block diagram showing a control system of engine 100. FIG. It is a flowchart which shows the process of ECU. It is a key map showing right and left bending which arises in an engine.

Explanation of symbols

69 Airflow sensor (parameter acquisition means)
71 Crank angle sensor (parameter acquisition means)
100 engine (internal combustion engine body)
120 ECU (setting means)
# 1, # 2, # 5, # 6 Cylinder located at the end in the arrangement direction # 3, # 4 Cylinder located at the end other than the end in the arrangement direction

Claims (4)

An internal combustion engine body in which a plurality of cylinders are arranged in a pair of banks;
Setting means for setting a combustion pressure of at least one cylinder located at a position other than the end in the arrangement direction to be smaller than a combustion pressure of a cylinder located at the end in the arrangement direction according to the operating state of the internal combustion engine body An internal combustion engine. Further comprising parameter acquisition means for acquiring a parameter relating to the operating state of the internal combustion engine body,
The internal combustion engine according to claim 1, wherein the setting unit determines whether or not to perform the setting based on the parameter acquired by the parameter acquisition unit. The internal combustion engine according to claim 2, wherein the parameter is at least one of a load factor of the internal combustion engine body and a rotation speed of the internal combustion engine body. In the setting, the fuel injection amount into at least one cylinder located at a position other than the end portion in the arrangement direction is made smaller than the fuel injection amount into a cylinder located at the end portion in the arrangement direction. The internal combustion engine according to any one of claims 1 to 3.

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