JP2009174410A - Engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve energy efficiency of the whole engine while generating plasma from air circulating in an intake passage for improving combustion efficiency, in an engine including a plasma generation means which generates plasma from air circulating in the intake passage and is attached to an intake device connected to an engine body and having the intake passage supplying air from the outside into a combustion chamber formed in an engine body while the tip of an ignition plug is faced thereto. <P>SOLUTION: A control means 83 controls electric power distribution to the plasma generation means 63 from an electric power supply means 82 with at least one of voltage and frequency varied, according to a result detected by an operating condition detection means 84 detecting the operating condition of the engine E. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention provides an intake passage connected to the engine body having an intake passage for supplying air from the outside to a combustion chamber formed in the engine body with the tip of the spark plug facing. The present invention relates to an engine provided with plasma generating means for converting air flowing through the air into plasma.

An engine in which combustion efficiency is improved by supplying a plasma mixture to a combustion chamber by applying a high voltage to a plasma generator attached to an intake device is known from Patent Document 1.
Japanese Patent Application Laid-Open No. 08-200190

  By the way, the combustion efficiency generally tends to be low in the low load / low rotation region of the engine and high in the high load / high rotation region. That is, it can be said that there is little room for improvement in combustion efficiency in the high load / high rotation region. In order to generate plasma in the low load / low rotation region, the fuel consumption can be expected to be reduced by making the air-fuel mixture into a plasma, but in the high load / high rotation region, the fuel consumption cannot be reduced as the low load / low rotation region. The increase in fuel consumption due to the necessary power consumption may exceed the amount of fuel consumption reduction due to the generation of plasma, which may lead to a reduction in the energy efficiency of the entire engine.

  The present invention has been made in view of such circumstances, and provides an engine in which the energy efficiency of the entire engine is improved while enabling the air flowing through the intake passage to be plasmatized in order to improve the combustion efficiency. Objective.

  In order to achieve the above object, the invention according to claim 1 has an intake passage for supplying air from the outside to a combustion chamber formed in the engine body with the tip of the spark plug facing. In an engine in which an air intake device connected to a main body is provided with plasma generating means for converting air flowing through the intake passage into plasma, electric power supply for supplying electric power with variable voltage and / or frequency to the plasma generating means Means, an operating state detecting means for detecting the operating state of the engine, and a control means for controlling power supply from the power supply means to the plasma generating means in accordance with a detection result of the operating state detecting means. Features.

  According to a second aspect of the present invention, in addition to the configuration of the first aspect of the present invention, the operating state detecting means includes a throttle opening degree sensor for detecting an opening degree of a throttle valve provided in the intake device and an engine speed. It has at least one of the engine speed sensors to detect.

  According to a third aspect of the invention, in addition to the configuration of the second aspect of the invention, the control means uses the plasma generation means except when the detected value by the operating state detection means is in a low rotation / low load region. The power supply means is controlled so as to avoid plasma generation.

  In addition to the configuration of the invention according to any one of claims 1 to 3, the invention according to claim 4 is characterized in that the control means has a low voltage and a high frequency when the required plasma generation amount by the plasma generation means is the same. The power supply means is controlled to supply power.

  According to the first to fourth aspects of the present invention, by controlling the power supply means in accordance with the operating state of the engine, appropriate plasma generation according to the operating state of the engine is realized, and the energy efficiency of the entire engine is increased. be able to.

  In particular, according to the third aspect of the present invention, although plasma is generated in a low load / low rotation region where a reduction in fuel consumption can be expected by making the air-fuel mixture into a plasma, the combustion efficiency is improved and the low load / low rotation region is achieved. The increase in fuel consumption due to the power consumption required to generate plasma may exceed the reduction in fuel consumption due to plasma generation by avoiding the generation of plasma in the high load / high rotation range where reduction in fuel consumption cannot be expected. In this way, the energy efficiency of the entire engine can be increased.

  Furthermore, according to the invention described in claim 4, it is possible to prevent undesired ignition in the intake passage. In other words, the amount of plasma generated is approximately proportional to the applied voltage and frequency, and even if the applied voltage is lowered, sufficient plasma can be generated by increasing the frequency. Can be prevented from igniting in the intake passage.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on one embodiment of the present invention shown in the accompanying drawings.

  1 to 9 show an embodiment of the present invention, FIG. 1 is a side view of a motorcycle to which the present invention is applied, FIG. 2 is a side view of the engine, and FIG. 3 is an enlarged vertical side view of the main part of the engine. 4 is a cross-sectional view taken along line 4-4 of FIG. 3, FIG. 5 is a diagram showing changes of non-plasma air and plasma air with respect to the engine load, and FIG. 6 is an enlarged cross-sectional view taken along line 6-6 of FIG. 7 is a diagram showing the relationship between the amount of ozone generated with respect to voltage and frequency, FIG. 8 is a diagram showing a frequency setting example according to the throttle opening and the engine speed, and FIG. 9 is a voltage setting according to the throttle opening and the engine speed. It is a figure which shows an example.

  First, in FIG. 1, an engine E to which the present invention is applied is an air-cooled single-cylinder four-stroke engine, and is mounted on a motorcycle in a lateral arrangement in which the axis of a crankshaft 11 is aligned in the vehicle width direction.

  A body frame F of the motorcycle includes a head pipe 13 that supports a front fork 12 that pivotally supports a front wheel WF, a main frame 14 that extends rearwardly downward from the head pipe 13, and a rear portion of the main frame 14. A pair of left and right rear frames 15 that extend rearward and a pivot plate 16 that is connected to the rear end of the main frame 14 and extends downward. A part of the engine E and the vehicle body frame F are provided by a vehicle body cover 17. Covered.

  A bar-shaped steering handle 18 is connected to the upper end portion of the front fork 12, and a rear wheel WR is mounted on the rear portion of a swing arm 20 that is pivotally supported on the pivot plate 16 via a pivot 19. A rear cushion unit 21 is provided between the left rear frame 15 and the swing arm 20 of the rear frames 15. Further, a fuel tank 23 disposed below the riding seat 22 disposed on the rear portion of the vehicle body frame F is provided between the rear portions of the rear frames 15.

  In FIG. 2, the engine body 25 of the engine E is coupled to the crankcase 26 with a crankcase 26 that rotatably supports the crankshaft 11 and a cylinder axis that is inclined forward so as to be substantially horizontal. A plurality of shift speeds selected from rotational power transmitted from the crankshaft 11, and a cylinder head 28 coupled to the cylinder block 27 on the opposite side of the crankcase 26. The transmission including the gear-type transmission mechanism that changes the speed is accommodated in the crankcase 26, and a power transmission including an endless chain 31 is provided between the output shaft 29 of the transmission and the axle 30 of the rear wheel WR. Means 32 are provided.

  Referring also to FIG. 3, a piston 34 is slidably fitted to a cylinder bore 33 formed in the cylinder block 27, and the piston 34 is connected to the crankshaft 11 via a connecting rod 35. Is done. A combustion chamber 36 that faces the top of the piston 34 is formed between the cylinder block 27 and the cylinder head 28 in the engine main body 25, and a spark plug 37 (see FIG. 4) faces its front end to the combustion chamber 36. And attached to the cylinder head 28.

  An intake port 39 that can communicate with the combustion chamber 36 is provided in the cylinder head 28 so as to open on the upper side wall of the cylinder head 28, and an exhaust port 40 that can communicate with the combustion chamber 36 is provided on the lower side wall of the cylinder head 28. An intake valve 41 that opens and closes the intake port 39 and an exhaust valve 42 that opens and closes the exhaust port 40 are disposed in the cylinder head 28 so as to be able to open and close while being biased in the valve closing direction.

  The intake valve 41 and the exhaust valve 42 have a cam shaft 43 that has an axis parallel to the crankshaft 11 and is rotatably supported by the cylinder head 28, and an intake side valve cam provided on the camshaft 43. 44, swinging is performed by an intake side rocker arm 46 interposed between the intake side valve cam 44 and the intake valve 41, and an exhaust side valve cam 45 provided on the camshaft 43. The camshaft 43 is driven to open and close by a valve operating device 48 having an exhaust side rocker arm 47 interposed between the exhaust side valve cam 45 and the exhaust valve 42. 11 is transmitted at a reduction ratio of 1/2.

  An exhaust device 49 is connected to the exhaust port 40, and the exhaust device 49 includes an exhaust pipe 50 having an upstream end connected to the lower side wall of the cylinder head 28 so as to communicate with the exhaust port 40, and An exhaust muffler 51 (see FIG. 1) disposed on the right side of the rear wheel WR and connected to the downstream end of the exhaust pipe 50.

  Referring also to FIG. 4, an intake device 53 is connected to the intake port 39. The intake device 53 is disposed obliquely above and forward of the engine body 25 and is supported by the main frame 14. An air cleaner 54, a throttle body 55 having an upstream end connected to the air cleaner 54, and an intake pipe 56 that connects the upper side wall of the cylinder head 28 and the downstream end of the throttle body 55 through the intake port 39. The intake pipe 56 is formed of an electrically and thermally insulating material such as rubber.

  In the throttle body 55 and the intake pipe 56 of the intake device 53, an intake passage 57 for supplying air introduced into the air cleaner 54 from the outside and purified by the air cleaner 54 from the intake port 39 to the combustion chamber 36. A butterfly throttle valve 58 that controls the opening degree of the intake passage 57 is fixed to a valve shaft 59 that is pivotally supported by the throttle body 55 and protrudes from the throttle body 55. A throttle wire 61 pulled by a driver's operation is wound around one end of the shaft 59, and the throttle drum 60 to be connected is fixed. The valve shaft 59 is spring-biased in the valve closing direction of the throttle valve 58. The

  A fuel injection valve 62 for injecting fuel into the intake passage 57 is attached to the throttle body 55 downstream of the throttle valve 58, and air whose flow rate is controlled by the throttle valve 58 is the fuel injection valve 62. When the intake valve 41 is opened, the air-fuel mixture formed by mixing with the fuel injected from the intake port 39 is supplied from the intake port 39 to the combustion chamber 36. Burns by ignition.

  The intake device 53 is provided with plasma generating means 63 for converting the air flowing through the intake passage 57 into plasma. The plasma generating means 63 is connected to the intake passage 57 upstream of the throttle valve 58. A downstream end of an air introduction pipe 64 that is connected to the throttle body 55 at an upstream end thereof and a downstream side of the throttle passage 55 that communicates with the intake passage 57 at a downstream side of the injection port 62a of the fuel injection valve 62. It is provided between the upstream end of the plasma supply pipe 65 to which the end is connected.

  An intermediate portion of the air introduction pipe 64 is provided with a shaft support portion 64a that rotatably supports the other end side of the valve shaft 59 to which the throttle valve 58 is fixed. The shaft support portion 64a is a throttle. Connected to the body 55. That is, the other end side of the valve shaft 59 is rotatably supported by the throttle body 55 and the shaft support portion 64a of the air introduction pipe 64, and an air introduction passage 66 formed in the air introduction pipe 64 is supported. An air control valve 67 for controlling the amount of air flow is provided in the valve shaft 59 in the air introduction passage 66. The air control valve 67 opens and closes in conjunction with the throttle valve 58 so that the opening degree of the throttle valve 58 increases as the opening degree of the throttle valve 58 increases. The air amount and the non-plasma air amount controlled by the throttle valve 58 increase as the engine load increases as shown in FIG.

  Thus, the total amount of the non-plasma air and the plasma air is supplied to the intake port 57 as intake air so that an air-fuel ratio suitable for the operating state of the engine E can be obtained. As indicated by the chain line, the ratio increases as the engine load increases, but the ratio of the plasma air amount to the non-plasma air amount increases as the engine load decreases. The amount of plasma air is larger than the amount of non-plasma air in the load operation region, and the amount of plasma air is smaller than the amount of non-plasma air in the high load operation region of the engine E. The opening degree of the air control valve 67 is set.

  Thus, when the ratio of the plasma air amount to the non-plasma air amount controlled by the throttle valve 58 is controlled so as to increase as the engine load decreases, it is set in the low load operating range of the engine E. The effect of improving combustibility can be enhanced while maintaining the air-fuel ratio, and the amount of plasma air is greater than the amount of non-plasma air in the low-load operation region of the engine E, so that the combustibility improvement effect is further enhanced. Can do.

  In FIG. 6, the plasma generating means 63 includes a housing 70 made of an electrical and thermal material, a cylindrical ground electrode 73 disposed in the housing 70 and fixed to the housing 70, and the ground electrode. 73, a cylindrical dielectric 72 fixedly disposed inside 73, and a columnar application electrode 71 disposed coaxially within the dielectric 72, and an annular discharge space between the application electrode 71 and the dielectric 72 76 is formed.

  The housing 70 is formed in a cylindrical shape having a small diameter cylindrical portion 70a at the downstream end thereof, and the upstream end of the housing 70 is coaxially connected to the downstream end of the air introduction pipe 64, and the small diameter cylindrical portion 70a is By fitting the upstream end of the plasma supply pipe 65, the downstream end of the housing 70 is connected to the upstream end of the plasma supply pipe 65.

  The dielectric 72 and the ground electrode 73 protrude from the upstream end of the housing 70 and are fitted to the downstream end of the air introduction pipe 64. The end portion of the dielectric 72 on the plasma supply tube 65 side is disposed so as to protrude from the application electrode 71 and the ground electrode 73 toward the plasma ejection direction, that is, the plasma supply tube 65 side. The simple arrangement structure prevents arcing between the application electrode 71 and the ground electrode 73.

  An application electrode side connection terminal 77 and a ground electrode side connection terminal 78 are provided at the end of the housing 70 on the air introduction pipe 64 side. The application electrode side connection terminal 77 is connected to the application electrode 71 via an electric wire 79. The ground electrode side connection terminal 78 is electrically connected to the ground electrode 73 via the electric wire 80.

  Thus, when a dielectric barrier discharge is generated between the application electrode 71 to which a voltage is applied and the ground electrode 73 in the discharge space 76, the plasma air guided by the air introduction tube 64 enters a plasma state to generate plasma. In addition, the air in the plasma state is controlled by the throttle valve 58 and mixed with the air mixed with the fuel from the fuel injection valve 62 on the downstream side of the injection port 62a of the fuel injection valve 62. Become.

  By the way, it is known that the plasma generation in the plasma generating means 63 is more effective as the generated atmospheric pressure becomes lower, and the vicinity of the compression top dead center, which is the time of ignition of the air-fuel mixture in the combustion chamber 36 or just before ignition, If the plasma can be generated in the combustion chamber 36 at a pressure corresponding to the compression pressure or a generation atmosphere lower than the compression pressure, the plasma generation efficiency can be increased. Can be reduced in size and weight, and energy consumption can be reduced.

  Therefore, in this embodiment, the annular discharge space 76 is communicated with the intake passage 57 downstream of the throttle valve 58, and the pressure is lower than the pressure of the combustion chamber 36 near the compression top dead center. Since the discharge space 76 communicates with the intake passage 57, the plasma generation efficiency of the plasma generation means 63 is increased, and the plasma generation means 63 can be reduced in size and weight and energy consumption can be reduced.

  A power supply means 82 is connected to the application electrode side connection terminal 77 and the ground electrode side connection terminal 78 of the plasma generation means 63, and the power supply means 82 can change at least one of voltage and frequency and change the plasma. Electric power can be supplied to the generating means 63.

  By the way, when air is turned into plasma, ozone, nitrogen oxides, highly reactive radicals, etc. are generated, and when the amount of plasma generated increases, the amount of ozone generated also increases, but as shown in FIG. The higher the higher the ozone generation amount, the higher the ozone generation amount as the frequency increases in sequence A, B, C, D, E (A <B <C <D <E) even at the same voltage. In the embodiment, the amount of plasma generated in the plasma generating means 63 is controlled by changing both the voltage and frequency of the power supplied from the power supply means 82 to the plasma generating means 63.

  Referring again to FIG. 2, the power supply from the power supply means 82 to the plasma generation means 63 is controlled by the control means 83. The control means 83 is input with the detection value of the operating state detecting means 84 for detecting the operating state of the engine E. The operating state detecting means 84 is the opening of the throttle valve 58 provided in the intake device 53. At least one of a throttle opening sensor 85 for detecting the engine speed and an engine speed sensor 86 for detecting the engine speed. In this embodiment, both the throttle opening sensor 85 and the engine speed sensor 86 are provided. The intake air temperature sensor 87 and the oil temperature sensor 88 are provided.

  Thus, as shown in FIG. 4, the throttle opening sensor 85 is connected to the end opposite to the throttle drum 60 of the valve shaft 59 provided with the throttle valve 58 and the air control valve 67. As shown in FIG. 2, the engine speed sensor 86 is fixed to the outer periphery of a pulsar 89 attached coaxially to the crankshaft 11 and is fixedly arranged to be attached to the shaft support 64a of the air introduction pipe 64. The air temperature sensor 87 is attached to the air cleaner 54 so as to detect the temperature of the air introduced into the air cleaner 54, and the oil temperature sensor 88 is detected so as to detect the temperature of the oil stored at the bottom of the crankcase 26. Mounted on.

  The control means 83 avoids the generation of plasma by the plasma generation means 63 except when the detection values of the throttle opening sensor 85 and the engine speed sensor 86 in the operating state detection means 84 are in the low rotation / low load region. The power supply means 82 is controlled as described above, and the frequency when in the low rotation / low load region is set as shown in FIG. 8, and the voltage when in the low rotation / low load region is shown in FIG. Set as shown. Moreover, such set values of frequency and voltage are corrected according to the intake air temperature and the oil temperature detected by the intake air temperature sensor 87 and the oil temperature sensor 88.

  Further, the control means 83 controls the power supply means 82 to supply low voltage and high frequency power when the plasma generation required amount by the plasma generation means 63 is the same.

  Next, the operation of this embodiment will be described. The plasma generating means 63 is supplied with electric power from the electric power supply means 82 with at least one of the voltage and frequency being variable, and an operating state detecting means 84 for detecting the operating state of the engine E. The control means 83 controls the power supply from the power supply means 82 to the plasma generation means 63 in accordance with the detection result of this, so that appropriate plasma generation according to the operating state of the engine E is realized, and the entire engine E is controlled. Energy efficiency can be increased.

  The operating state detecting means 84 includes at least one of a throttle opening degree sensor 85 that detects the opening degree of the throttle valve 58 and an engine speed sensor 86 that detects the engine speed, and the control means 83 includes the operating state. The power supply means 82 is controlled so as to avoid the generation of plasma by the plasma generation means 63 except when the detection value by the detection means 84 is in the low rotation / low load region. Plasma is generated in the low load / low rotation region where reduction of fuel consumption can be expected to improve combustion efficiency, but plasma is not generated in the high load / high rotation region where reduction in fuel consumption cannot be expected in the low load / low rotation region Thus, the increase in fuel consumption due to the power consumption necessary to generate plasma is due to plasma generation. As never exceed the fuel consumption amount, it is possible to increase the energy efficiency of the entire engine E.

  Further, since the control means 83 controls the power supply means 82 to supply low voltage and high frequency power when the plasma generation required amount by the plasma generation means is the same, undesired ignition in the intake passage 57 is caused. It can be prevented from occurring. That is, as shown in FIG. 7, the plasma generation amount is substantially proportional to the applied voltage and frequency, and even if the applied voltage is lowered, sufficient plasma can be generated by setting the frequency high. The voltage can be made as low as possible so that the air-fuel mixture does not ignite in the intake passage 57.

  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. It is.

  For example, although the case where the present invention is applied to the engine E for a motorcycle has been described in the above embodiment, the present invention can also be applied to an engine for a passenger car, an engine for an engine, and an engine generator.

1 is a side view of a motorcycle to which the present invention is applied. It is a side view of an engine. It is a principal part expansion vertical side view of an engine. FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. It is a figure which shows the change with respect to the engine load of the air for non-plasma and the air for plasma. FIG. 6 is an enlarged sectional view taken along line 6-6 in FIG. It is a figure which shows the relationship of the ozone generation amount with respect to a voltage and a frequency. It is a figure which shows the example of a frequency setting according to a throttle opening and an engine speed. It is a figure which shows the example of a voltage setting according to a throttle opening and an engine speed.

Explanation of symbols

25 ... Engine body 36 ... Combustion chamber 37 ... Spark plug 53 ... Intake device 57 ... Intake passage 58 ... Throttle valve 63 ... Plasma generating means 82 ... Power supply means 83 ... Control means 84 ... Operating state detection means 85 ... Throttle opening sensor 86 ... Engine speed sensor E ... Engine

Claims (4)

  The engine body (25) has an intake passage (57) for supplying air from the outside to a combustion chamber (36) formed in the engine body (25) with the front end of the spark plug (37) facing. In an engine in which a plasma generating means (63) for converting the air flowing through the intake passage (57) into a plasma is attached to an intake device (53) connected to the plasma generator, the plasma generating means (63) has a voltage and a frequency. According to the detection result of the power supply means (82) for supplying power with variable at least one, the driving state detection means (84) for detecting the driving state of the engine (E), and the driving state detection means (84) An engine comprising: control means (83) for controlling power supply from the power supply means (82) to the plasma generation means (63).   The operating state detection means (84) detects the opening of a throttle valve (58) included in the intake device (53), and an engine speed sensor (86) detects the engine speed. The engine according to claim 1, comprising at least one of the following.   The control means (83) is configured to avoid the generation of plasma by the plasma generation means (63) except when the value detected by the operation state detection means (84) is in a low rotation / low load region. The engine according to claim 2, wherein (82) is controlled.   The control means (83) controls the power supply means (82) so as to supply low voltage and high frequency power when the plasma generation required amount by the plasma generation means (63) is the same. The engine according to any one of claims 1 to 3.

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