JP2011214532A - Internal combustion engine with auxiliary chamber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold open an auxiliary valve longer to allow an intake amount control under lower load than ever before, in an internal combustion engine with auxiliary chamber, in which an auxiliary chamber is connected to an auxiliary port, and an ignition plug of which the tip faces a combustion chamber is mounted to a cylinder head.SOLUTION: The ignition plug 60A of which the ignition timing is during the opening of the auxiliary valve 30 is mounted to the cylinder head 13 so that the tip thereof faces the combustion chamber 14 at a position symmetric with the auxiliary valve 30 with respect to a center C of the combustion chamber 14.

Description

  In the present invention, a combustion chamber is formed between a cylinder block having a cylinder bore and a cylinder head coupled to the cylinder block so as to face a top of a piston slidably fitted to the cylinder bore. An intake valve, an exhaust valve, and a sub-chamber valve for switching communication / blocking of the intake port, exhaust port, and sub-chamber port provided in the cylinder head to the combustion chamber are respectively disposed in the head so as to be openable and closable. The present invention relates to an internal combustion engine with a sub chamber in which a sub chamber is connected to a chamber port, and a spark plug that faces the tip of the combustion chamber is attached to the cylinder head.

  Such an internal combustion engine with a sub chamber is already known from Patent Document 1.

Japanese Patent Laid-Open No. 11-166431

  By the way, by introducing a part of the air-fuel mixture in the combustion chamber into the sub chamber while controlling the amount in the compression stroke, it is possible to perform intake control of the engine without the need for a throttle valve on the intake device side. I want to control the introduction of the air-fuel mixture into the subchamber up to a lower load. However, in an internal combustion engine in which an ignition plug is disposed in the center of the combustion chamber, and an intake port, an exhaust port, and a sub chamber port are disposed close to the combustion chamber wall surface around the ignition plug, the sub chamber port is located near the ignition plug. Since the flame due to ignition of the spark plug reaches the sub chamber port side immediately, it is necessary to close the sub chamber valve so that it is not affected by the flame. If it tries to open and use the sub chamber (until the end of the stroke), it will be necessary to delay the ignition timing accordingly, and efficient ignition will not be possible. For this reason, it is necessary to close the sub-chamber valve before the ignition timing in the latter half of the compression stroke, which limits the intake air amount control.

  The present invention has been made in view of such circumstances, and the sub-chamber internal combustion engine that enables the intake air amount control at a lower load by enabling the sub-chamber valve to be opened longer. The purpose is to provide.

  In order to achieve the above object, according to the present invention, the top of a piston slidably fitted to the cylinder bore faces between a cylinder block having a cylinder bore and a cylinder head coupled to the cylinder block. A combustion chamber is formed, and an intake valve, an exhaust valve, and a sub-chamber valve for switching communication / blocking of the intake port, exhaust port, and sub-chamber port provided in the cylinder head to the combustion chamber are opened / closed respectively. In an internal combustion engine with a sub chamber in which a sub chamber is connected to the sub chamber port and a spark plug that faces the tip of the combustion chamber is attached to the cylinder head, the sub chamber valve is opened. The spark plug, which is the ignition timing, faces the tip of the combustion chamber at a position symmetrical to the sub-chamber valve across the center of the combustion chamber. That is attached to the cylinder head in the first feature.

  According to the present invention, in addition to the configuration of the first feature, a control valve is provided between the sub chamber and the combustion chamber to vary the pressure generated in the sub chamber and the amount of air stored in the sub chamber. This is a second feature.

  In the present invention, in addition to the configuration of the first feature, a second spark plug different from the first spark plug has a tip at a position closer to the sub chamber valve than the first spark plug. A third feature is that it is attached to the cylinder head so as to face the combustion chamber.

  According to the present invention, in addition to the configuration of the third feature, the intake valve and the exhaust valve are provided on both sides of a single camshaft provided in a valve mechanism that opens and closes the intake valve, the exhaust valve, and the sub chamber valve. The fourth feature is that the first and second spark plugs and the sub-chamber valve are disposed on both sides of the camshaft.

  The fifth feature of the present invention is that, in addition to the configuration of the third or fourth feature, the ignition timing of the second spark plug is set after the sub chamber valve is closed.

  The sixth feature of the present invention is that, in addition to any of the third to fifth features, the ignition timing of the second spark plug is set later than the ignition timing of the first spark plug. And

  In the present invention, in addition to any one of the third to sixth features, the ignition of one of the first and second spark plugs is retarded or cut in an operating state at an engine speed equal to or higher than a predetermined speed. This is the seventh feature.

  In the present invention, in addition to any one of the third to sixth features, the ignition of one of the first and second spark plugs is retarded or cut in an operating state at an engine speed equal to or higher than a predetermined speed. In addition, an eighth feature is that the other ignition timing of the first and second spark plugs is made earlier than the ignition timing in the operating state at the engine speed less than the predetermined engine speed.

  Furthermore, in addition to the configuration of the eighth feature, the present invention provides that the ignition timings of the first and second spark plugs are set simultaneously in a low-speed operation state where the engine speed is equal to or less than the set speed. Features.

  According to the first feature of the present invention, since the tip of the spark plug faces the combustion chamber at a position symmetrical to the sub chamber valve across the center of the combustion chamber, the tip of the spark plug is positioned far from the sub chamber valve. By arranging, the sub chamber valve can be opened longer and the intake air amount control at a low load becomes possible. In particular, since the flame propagation is slow during operation at low speed, the sub-chamber valve can be opened immediately after ignition.

  According to the second feature of the present invention, since the pressure generated in the sub chamber and the amount of air stored in the sub chamber are variably controlled by the control valve, the expansion ratio is controlled to be variable according to the operating state of the engine. Compression is possible.

  According to the third aspect of the present invention, the first and second spark plugs are arranged such that the tip of the second spark plug faces the combustion chamber at a position closer to the sub chamber valve than the first spark plug. Since it is attached to the cylinder head, the sub-chamber port and the first and second spark plugs can be arranged in a limited combustion chamber space so as not to interfere with each other. Thus, efficient combustion is possible, and the ignition timing can be delayed.

  According to the fourth aspect of the present invention, the intake valve and the exhaust valve are disposed on both sides of a single camshaft included in the valve mechanism, and the first and second spark plugs, the sub chamber valve, Therefore, an intake port, an exhaust port, a sub chamber port, and a pair of spark plugs can be arranged in a limited combustion chamber space.

  According to the fifth feature of the present invention, the ignition timing of the second spark plug located closer to the sub chamber valve than the first spark plug is set after the sub chamber valve is closed. It is possible to improve the combustion efficiency by delaying the ignition timing so that the influence of the flame by the spark plug does not occur on the side of the sub chamber.

  According to the sixth aspect of the present invention, the first and second spark plugs ignite with a phase difference, and the ignition timing of the first spark plug far from the sub chamber valve is close to the sub chamber valve. The ignition timing of the second ignition plug on the side is made earlier so that the entire ignition timing is delayed, and the intake amount control up to a low load is possible while improving the combustion efficiency. It can be made difficult to receive.

  According to the seventh feature of the present invention, in the operating state at the engine speed equal to or higher than the predetermined speed, the in-cylinder flow is improved and the combustion is accelerated, so that both the first and second spark plugs are connected. There is no need to ignite, it is possible to retard or cut one ignition of the first and second spark plugs and respond only by the other ignition, and it is possible to retard or cut unnecessary ignition.

  According to the eighth aspect of the present invention, in an operating state at an engine speed equal to or higher than a predetermined speed, one ignition of the first and second spark plugs is retarded or cut, and the ignition timing of the other spark plug is Since it is advanced, the ignition timing can be advanced as the in-cylinder flow is improved and the combustion is accelerated.

  Further, according to the ninth feature of the present invention, since the first and second spark plugs are ignited simultaneously in the low speed operation state where the engine speed is equal to or lower than the set speed, the ignition is performed so as to efficiently transmit the flame. The timing can be delayed and the sub chamber valve can be opened longer.

It is a principal part longitudinal cross-sectional view of the internal combustion engine with a subchamber of Example 1, Comprising: It is sectional drawing which follows the 1-1 line | wire of FIG. FIG. 2 is a view taken along line 2-2 of FIG. 1 in a state where a head cover is omitted. It is a figure which cuts and shows a part seeing from the direction which follows the 3-3 line of FIG. It is a figure which shows the ignition timing of a spark plug. It is a figure which shows the lift characteristic of an intake valve, an exhaust valve, and a sub chamber valve. 1 is a side view of a motorcycle equipped with an internal combustion engine with a sub chamber. It is a figure which shows the relationship between a net average effective pressure and a net fuel consumption rate. FIG. 4 is a diagram corresponding to FIG. 3 of the second embodiment.

  Embodiments of the present invention will be described with reference to the accompanying drawings.

  A first embodiment of the present invention will be described with reference to FIGS. 1 to 6. First, in FIG. 1, the internal combustion engine E includes a cylinder block 12 having a cylinder bore 11 and a cylinder head 13 coupled to the cylinder block 12. A combustion chamber 14 is formed between the cylinder block 12 and the cylinder head 13 so as to face the top of the piston 15 slidably fitted to the cylinder bore 11.

  2 and 3 together, the cylinder head 13 is provided with an intake port 16, an exhaust port 17 and a sub chamber port 18 to form an intake passage 19 communicating with the intake port 16. An intake device 21 including an intake pipe 20 is connected to the cylinder head 13, and a fuel injection valve 22 that injects fuel toward the intake passage 19 is attached to the intake pipe 20. An exhaust device (not shown) is connected to the cylinder head 13 so as to be connected to the exhaust port 17.

  By the way, the cylinder head 13 has four first to fourth bolt insertion holes 24, 25, 26, through which stud bolts 23, 23... For connecting the cylinder head 13 to the cylinder block 12 and the crankcase side are inserted. 27 is provided so as to be circumferentially spaced around the combustion chamber 14, and the intake port 16 extends from the combustion chamber 14 between the first and second bolt insertion holes 24, 25 to the cylinder. The exhaust port 17 is disposed so as to open to the first side surface 13 a of the head 13, and the exhaust port 17 passes between the third and fourth bolt insertion holes 26 and 27 from the combustion chamber 14 and the first side surface 13 a of the cylinder head 13. Are arranged so as to open to the second side surface 13b on the opposite side. The sub chamber port 18 is arranged so as to open from the combustion chamber 14 to the third side surface 13c of the cylinder head 13 through the second and third bolt insertion holes 25 and 26, and the third side surface. 13c is a side surface arrange | positioned in the position which faces the direction orthogonal to the direction which 1st and 2nd side surface 13a, 13b faces.

  In the cylinder head 13, an intake valve 28, an exhaust valve 29 and a sub chamber valve for switching communication / blocking of the intake port 16, the exhaust port 17 and the sub chamber port 18 to the combustion chamber 14 can be opened and closed, respectively. The intake valve 28, the exhaust valve 29, and the sub chamber valve 30 are urged toward the valve closing side by valve springs 31, 32, 33 provided between the cylinder head 13.

  A valve operating mechanism 35 that opens and closes the intake valve 28, the exhaust valve 29, and the sub chamber valve 30 is a valve operating chamber 36 formed between the cylinder head 13 and a head cover 34 coupled to the cylinder head 13. It is stored in. Thus, the valve mechanism 35 includes a single camshaft 37 that is common to the intake valve 28, the exhaust valve 29, and the sub chamber valve 30, and the rotation of the camshaft 37 to rotate the intake valve 28, the exhaust valve 28, and the exhaust valve 28. An intake valve rocker arm 38, an exhaust valve rocker arm 39, and a sub chamber valve rocker arm 40 that drive the valve 29 and the sub chamber valve 30 to the valve opening side are provided.

  One end of the camshaft 37 passes through a first cam holder 41 provided in the cylinder head 13 in a rotatable manner, and a ball bearing 43 is interposed between the first cam holder 41 and the camshaft 37. Further, the other end of the camshaft 37 rotates via a ball bearing 44 to a second cam holder 42 provided on the cylinder head 13 at a position spaced from the first cam holder 41 in a direction along the axis of the camshaft 37. It is supported freely.

  On the camshaft 37, an intake cam 46 corresponding to the intake valve 28, an exhaust cam 47 corresponding to the exhaust valve 29, and a sub chamber cam 48 corresponding to the sub chamber valve 30 are spaced apart in the axial direction. Provided.

  The first and second cam holders 41 and 42 support both ends of a first rocker shaft 49 and a second rocker shaft 50 disposed on both sides of the axis of the camshaft 37. An intake valve rocker arm 38 and a sub chamber valve rocker arm 40 are swingably supported on the first rocker shaft 49, and rollers 51 are respectively pivotally supported at one ends of the intake valve rocker arm 38 and the sub chamber valve rocker arm 40. , 52 are in rolling contact with the intake cam 46 and the sub chamber cam 48. Further, tappet screws 54 and 55 are screwed into the other ends of the intake valve rocker arm 38 and the sub chamber valve rocker arm 40 so as to be able to adjust the advance and retreat positions along the axial direction. It contacts the stem ends of the intake valve 28 and the sub chamber valve 30.

  An exhaust valve rocker arm 39 is swingably supported on the second rocker shaft 50, and a roller 53 pivotally supported on one end of the exhaust valve rocker arm 39 is in rolling contact with the exhaust cam 47. Further, a tappet screw 56 is screwed to the other end of the exhaust valve rocker arm 39 so as to be able to adjust the advance / retreat position along the axial direction, and the tappet screw 56 contacts the stem end of the exhaust valve 29.

  At one end of the camshaft 37, that is, at the projecting end of the camshaft 37 from the first cam holder 41, a cam chain passage 59 for running a cam chain 57 that transmits rotational power from the crankshaft is connected to the cylinder block 12 and Provided in the cylinder head 13. That is, a driven sprocket 58 is fixed to the projecting end portion of the cam shaft 37 from the first cam holder 41, and the cam chain 57 is wound around the driven sprocket 58.

  The sub chamber port 18 is provided in the cylinder head 13 so as to be positioned on the opposite side of the cam chain passage 59 with respect to the combustion chamber 14, and this sub chamber port 18 is provided on the combustion chamber 14 side when mounted on a vehicle body. It forms so that it may become a downward slope toward.

  The cylinder head 13 is provided with first and second spark plugs 60A and 60B that face the tip of the combustion chamber 14. The first spark plug 60A has a center C of the combustion chamber 14. The second spark plug 60B is attached to the cylinder head 13 so that the front end faces the combustion chamber 14 at a position symmetrical to the sub chamber valve 30 with the second spark plug 60B interposed therebetween. The second spark plug 60B is more than the first spark plug 60A. In the first embodiment, the front end faces the combustion chamber 14 between the intake port 16 and the sub chamber port 18 and is attached to the cylinder head 13.

  In addition, the intake valve 28 and the exhaust valve 29 are disposed on both sides of the single camshaft 37 provided in the valve operating mechanism 35, whereas the first and second spark plugs 60A and 60B and the sub chamber valve are provided. 30 are arranged on both sides of the camshaft 37. That is, as shown in FIG. 3 on the projection onto the plane orthogonal to the axis of the cylinder bore 11, the intake port 16 and the sub chamber port 18 are arranged on one side of the center axis CL of the camshaft 37, and the center axis The exhaust port 17 and the first and second spark plugs 60A and 60B are disposed on the other side of CL.

  The ignition timing of the second ignition plug 60B is set after the sub chamber valve 30 is closed, and the ignition timing of the second ignition plug 60B is set later than the ignition timing of the first ignition plug 60A. .

  In addition, in the operating state of the engine speed equal to or higher than the predetermined speed, in the first embodiment, the ignition of the second spark plug 60B is retarded or cut in the first and second spark plugs 60A and 60B. On the other hand, in the first embodiment, the ignition timing of the first spark plug 60A is advanced earlier than the ignition timing in the operating state of the engine speed less than the predetermined speed, for example, the sub spark plug 60A, 60B. In the internal combustion engine having no chamber, the ignition timing when the ignition is performed with one spark plug is advanced. Thus, the predetermined rotational speed is 2/3 or more of the maximum rotational speed. For example, when the maximum output generation rotational speed is 8000 rpm, the predetermined rotational speed is set to 5000 rpm.

  The ignition timings of the first and second spark plugs 60A and 60B are as shown in FIG. 4. In FIG. 4, the ignition timing of the first spark plug 60A is L1, and the second ignition plug The ignition timing of the plug 60B is indicated by L2. For reference, the ignition timing when igniting with one spark plug in an internal combustion engine having no sub chamber is L3, and the ignition timing when igniting simultaneously with two spark plugs in an internal combustion engine without a sub chamber is Indicated by L4.

  Incidentally, the valve opening lift characteristics of the intake valve 28, the exhaust valve 29 and the sub chamber valve 30 by the intake cam 46, the exhaust cam 47 and the sub chamber cam 48 are as shown in FIG. The valve starts to open at some point between the opening timing of the intake valve 28 and the timing at which the compression stroke starts. The valve closing timing has a phase difference between the ignition timings of the first and second spark plugs 60A and 60B. By having it, it is possible to make it slower than the characteristics when a pair of spark plugs are ignited simultaneously. The ignition timing of the second ignition plug 60B having the later ignition timing when the ignition timing of the first and second ignition plugs 60A and 60B has a phase difference is shown by θA in FIG. The ignition timing when the pair of ignition plugs are simultaneously ignited is indicated by θB in FIG.

  A sub chamber 61 is connected to the sub chamber port 18 to open a sub chamber valve 30 during the compression stroke of the piston 15 to guide a part of the air-fuel mixture in the combustion chamber 14. The sub chamber housing 62 forming 61 is fastened to the cylinder head 13 via the connecting cylinder portion 63, and the sub chamber housing 62 and the connecting cylinder portion 63 are integrally formed.

  A part of the air-fuel mixture in the combustion chamber 14 flows from the sub chamber port 18 to the sub chamber side by opening the sub chamber valve 30 in the compression stroke. A butterfly valve 64 serving as a control valve for varying the pressure generated in the chamber 61 and the amount of air stored in the sub chamber 61 is provided. The valve shaft 65 of the butterfly valve 64 is connected to the connecting cylinder portion 63. It is pivotally supported.

  Thus, the sub-chamber valve 30 opens somewhere from the opening timing of the intake valve 28 to the time when the compression stroke starts, and opens until the ignition timing in the latter half of the compression stroke. By opening the valve 64, the air and fuel sucked from the intake port 16 are pushed out to the sub chamber 61 in the compression stroke, but the required output is obtained by changing the ventilation resistance by controlling the opening of the butterfly valve 64. The engine output can be minimized when the butterfly valve 64 is fully opened and maximized when the butterfly valve 64 is fully closed. In this way, by introducing a part of the air-fuel mixture from the combustion chamber 14 to the sub chamber 61 and controlling the amount thereof, the intake air amount is substantially controlled, so that no throttle valve is required on the intake device 21 side.

  By the way, when controlling the amount of air-fuel mixture introduced into the sub chamber, it is possible to change the volume of the chamber by moving one end of the piston into the sub chamber and operating the piston. A strong structure that can withstand the high pressure acting from the combustion chamber 14 side in the compression stroke is required on the piston side, and it is difficult to seal the leakage of the sliding portion. On the other hand, in the above-described structure in which the air flow resistance is changed by the butterfly valve 64 arranged between the combustion chamber 14 and the sub chamber 61, the amount of the air-fuel mixture introduced into the sub chamber 61 is controlled. Therefore, the structure of the movable part can be simplified, and the ventilation resistance is changed by the rotation of the butterfly valve 64. Therefore, it is easy to cope with leakage.

  Further, by pushing the air-fuel mixture from the combustion chamber 14 to the sub chamber 61, the pumping loss can be reduced similarly to the mirror cycle, and the output control is performed by opening the butterfly valve 64, so the load is low. As the pumping loss is reduced, the effect increases. Further, during full load operation, the butterfly valve 64 is fully closed, but the passage volume between the sub chamber valve 30 and the butterfly valve 64 is pushed out of the combustion chamber 14, so that the durability against knocking is improved, and accordingly, It becomes possible to increase the geometric compression ratio, and at the time of low load, it is possible to reduce the fuel consumption by the improvement of the expansion ratio. Further, since there is no throttle valve on the intake device 21 side even at a low load, a strong in-cylinder flow similar to that when the throttle valve is fully opened can be generated in the combustion chamber 14, and a lean combustion operation becomes possible.

  A cable (not shown) for transmitting a driving force for opening and closing the butterfly valve is wound around one end portion of the valve shaft 65 protruding from the connecting cylinder portion 63, and a drum 66 to be connected is fixed. A rotation position detection sensor 67 supported by the sub chamber housing 62 is coaxially connected to the other end portion of the valve shaft 65 protruding from the connection cylinder portion 63.

  As shown in FIG. 5, such an internal combustion engine E with a sub chamber is mounted on a motorcycle, for example, and is supported by a head pipe 75 at the front end of a vehicle body frame F included in the motorcycle so as to be steerable. The sub-chamber internal combustion engine E is mounted on the vehicle body frame F so as to be disposed between the front wheel WF and the rear wheel WF that are pivotally supported at the lower end of the front fork 76, and the rear wheel WR The front end of the swing arm 77 is pivotally supported by F at the rear end of the swing arm 77.

  Thus, in the internal combustion engine E with the sub chamber, the air intake device 21 connected to the cylinder head 13 rises upward from the cylinder head 13 so that the sub chamber 61 is arranged on the right side in the traveling direction of the motorcycle. Mounted on the frame F.

  Next, the operation of the first embodiment will be described. A camshaft 37 included in the valve mechanism 35 is rotatably supported by the cylinder head 13 and a cam chain 57 that transmits rotational power to one end of the camshaft 37 is caused to travel. Cam chain passage 59 is provided in cylinder block 12 and cylinder head 13, and subchamber port 18 is disposed on the opposite side of cam chamber passage 59 with respect to combustion chamber 14, so camshaft 37, intake valve 28, and exhaust The position of the sub chamber port 18 can be determined without considering interference with the valve 29 or the like. Moreover, since the sub chamber port 18 is inclined downward toward the combustion chamber 14 when the vehicle body is mounted, it is possible to prevent fuel droplets from staying in the sub chamber 61.

  Further, the first spark plug 60A, which is the ignition timing while the sub chamber valve 30 is opened, faces the combustion chamber 14 at a position symmetrical to the sub chamber valve 30 with the center C of the combustion chamber 14 in between. Since the tip of the first spark plug 60A is disposed far from the sub chamber valve 30, the sub chamber valve 30 can be opened longer and placed at a low load. Intake amount control is possible. In particular, since the flame propagation is slow during operation at a low speed, the sub-chamber valve 30 can be kept open immediately after ignition.

  In addition, a butterfly valve 64 is provided between the sub chamber 61 and the combustion chamber 14 so that the pressure generated in the sub chamber 61 and the amount of air stored in the sub chamber 61 are variable. Variable compression according to the state becomes possible.

  Also, a second spark plug 60B different from the first spark plug 60A is attached to the cylinder head 13 with the tip facing the combustion chamber 14 at a position closer to the sub chamber valve 30 than the first spark plug 60A. Therefore, the sub chamber port 18 and the first and second spark plugs 60A and 60B can be arranged in a limited space of the combustion chamber 14 so as not to interfere with each other, and a pair of spark plugs With 60A and 60B, efficient combustion is possible, and the ignition timing can be delayed.

  An intake valve 28 and an exhaust valve 29 are disposed on both sides of a single camshaft 37 provided in the valve mechanism 35, and the first and second spark plugs 60A and 60B and the sub chamber valve 30 are connected to each other by a cam. Since it is disposed on both sides of the shaft 37, the intake port 16, the exhaust port 17, the sub chamber port 18, and the pair of spark plugs 60 </ b> A and 60 </ b> B can be disposed in a limited space of the combustion chamber 14.

  Further, since the ignition timing of the second ignition plug 60B is set after the sub chamber valve 30 is closed, the ignition timing of the second ignition plug 60B located closer to the sub chamber valve 30 than the first ignition plug 60A. Is set after the sub chamber valve 30 is closed, and the ignition timing is delayed so that the influence of the flame by the second spark plug 60B does not occur on the sub chamber 61 side, thereby improving the combustion efficiency. be able to.

  Moreover, since the ignition timing of the second spark plug 60B is set later than the ignition timing of the first spark plug 60A, the first and second spark plugs 60A and 60B ignite with a phase difference. The ignition timing of the first ignition plug 60A on the side far from the sub chamber valve 30 is made earlier than the ignition timing of the second ignition plug 60B on the side near the sub chamber valve 30, and the entire ignition timing is delayed. It is possible to control the intake air amount up to a low load while increasing the combustion efficiency, and to make it difficult for the sub chamber 61 side to be affected by the propagation of the flame.

  Further, in the operating state of the engine speed equal to or higher than the predetermined speed, the ignition of one of the first and second spark plugs 60A and 60B, in the first embodiment, the second spark plug 60B is retarded or cut. Since the in-cylinder flow is improved and the combustion is accelerated in the operating state of the engine speed equal to or higher than the predetermined speed, it is not necessary to ignite both the first and second spark plugs 60A and 60B. The ignition of the second spark plug 60B can be retarded or cut to cope with only the ignition of the first spark plug 60, and unnecessary ignition can be cut.

  Further, in the operating state of the engine speed equal to or higher than the predetermined speed, in the first embodiment, the ignition timing of the first spark plug 60A in the first embodiment is different from that of the first and second spark plugs 60A and 60B. Since the ignition timing in the operating state at the rotational speed is advanced, the ignition timing can be advanced as the in-cylinder flow is improved and the combustion is accelerated.

  FIG. 6 shows the relationship between the net average effective pressure and the net fuel consumption rate when control is performed to give a phase difference to the ignition of the first and second spark plugs 60A and 60B. Compared with the curve indicated by the thick solid line when the two spark plugs are ignited simultaneously, the operable region can be expanded to the low load side where the effect is greater.

  By the way, in the low speed operation state where the engine speed is equal to or lower than the set speed, the ignition timings of the first and second spark plugs 60A and 60B may be set simultaneously as shown by L5 in FIG. In the low speed operation state where the engine speed is equal to or lower than the set speed, the ignition timing can be delayed by efficiently transmitting the flame, and the sub chamber valve 30 can be opened longer.

  A second embodiment of the present invention will be described with reference to FIG. 8, but the portions corresponding to the first embodiment are only shown with the same reference numerals and will not be described in detail.

  A valve housing 68 having a circular cross section is connected to the cylinder head 13, and a rotary valve 69, which is a control valve, is rotatably fitted in the valve housing 68, and a sub chamber 71 is placed in the rotary valve 69. Is formed.

  An opening 70 is provided in one circumferential direction of the rotary valve 69 so that the sub chamber port 18 communicates with the sub chamber 71. The opening area of the opening 70 changes as the rotary valve 69 rotates. The ventilation resistance is changed, whereby the pressure generated in the sub chamber 71 and the amount of air stored in the sub chamber 71 can be made variable.

  According to the second embodiment, since the sub chamber 71 is formed in the rotary valve 69, the sub chamber 71 can be formed with a more simplified structure, and precise variable compression control can be performed.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. Is possible.

11 ... Cylinder bore 12 ... Cylinder block 13 ... Cylinder head 14 ... Combustion chamber 15 ... Piston 16 ... Intake port 17 ... Exhaust port 18 ... Sub chamber port 28 ... Intake valve 29 ... exhaust valve 30 ... sub chamber valve 35 ... valve operating mechanism 37 ... camshaft 60A ... first spark plug 60B ... second spark plugs 61, 71 ... Sub chamber 64 ... Butterfly valve 69 as control valve ... Rotary valve C as control ... Center of combustion chamber

Claims (9)

  A piston (15) slidably fitted to the cylinder bore (11) between a cylinder block (12) having a cylinder bore (11) and a cylinder head (13) coupled to the cylinder block (12). ) Is formed, and the cylinder head (13) has an intake port (16), an exhaust port (17), and a sub chamber port (18) provided in the cylinder head (13). An intake valve (28), an exhaust valve (29), and a sub chamber valve (30) for switching the communication between the communication chamber and the combustion chamber (14) are arranged to be openable and closable, and are connected to the sub chamber port (18). An internal combustion engine with a subchamber to which a subchamber (61, 71) is connected and a spark plug (60A) that faces the tip of the combustion chamber (14) is attached to the cylinder head (13). A position where the spark plug (60A) that is ignited during opening of the sub chamber valve (30) is symmetrical with the sub chamber valve (30) across the center (C) of the combustion chamber (14). An internal combustion engine with a sub-chamber, wherein the internal combustion engine is attached to the cylinder head (13) with its tip facing the combustion chamber (14).   Between the sub chamber (61) and the combustion chamber (14), there are control valves (64, 69) for varying the pressure generated in the sub chamber (61) and the amount of air stored in the sub chamber (61). The internal combustion engine with a sub chamber according to claim 1, wherein the internal combustion engine is provided with a sub chamber.   A second spark plug (60B) different from the first spark plug (60A) has its tip at the position closer to the sub chamber valve (30) than the first spark plug (60A). The internal combustion engine with a sub-chamber according to claim 1, wherein the internal combustion engine is attached to the cylinder head (13) so as to face (14).   The intake valve (28) and the exhaust valve (29) are provided with a single cam provided in a valve mechanism (35) for opening and closing the intake valve (28), the exhaust valve (29) and the sub chamber valve (30). It is disposed on both sides of the shaft (37), and the first and second spark plugs (60A, 60B) and the sub chamber valve (30) are disposed on both sides of the camshaft (37). The internal combustion engine with a sub chamber according to claim 3.   The internal combustion engine with a sub chamber according to claim 3 or 4, wherein the ignition timing of the second spark plug (60B) is set after the sub chamber valve (30) is closed.   The internal combustion engine with a sub chamber according to any one of claims 3 to 5, wherein the ignition timing of the second spark plug (60B) is set later than the ignition timing of the first spark plug (60A). organ.   7. The ignition of one of the first and second spark plugs (60 </ b> A, 60 </ b> B) is retarded or cut in an operating state at an engine speed equal to or higher than a predetermined speed. The internal combustion engine with a subchamber as described.   In an operating state at an engine speed equal to or higher than a predetermined speed, one ignition of the first and second spark plugs (60A, 60B) is retarded or cut, and the first and second spark plugs (60A, 60B). The internal combustion engine with a sub-chamber according to any one of claims 3 to 6, wherein the other ignition timing is advanced earlier than the ignition timing in an operating state at an engine speed less than a predetermined engine speed.   9. An internal combustion engine with a sub-chamber according to claim 8, wherein the ignition timing of the first and second spark plugs (60A, 60B) is set simultaneously in a low speed operation state where the engine speed is equal to or lower than the set speed. .

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